Abstract. We consider the effects of a pressure gradient on the spontaneous flow of an active nematic liquid crystal in a channel, subject to planar anchoring and no-slip conditions on the boundaries of the channel. We employ a model based on the Ericksen-Leslie theory of nematics, with an additional active stress accounting for the activity of the fluid. By directly solving the flow equation, we consider

Abstract. The electrolytic conductivity of two electrolytes as solutions in the nonpolar solvent, n -dodecane, as a function of concentration has been studied. One was a small molecule electrolyte (tetraalkyl cation and a highly fluorinated tetraphenylborate anion), and the other was a macromolecular electrolyte (cation-containing poly(alkyl methacrylate) chain with the same anion). Two series of the

Abstract. The development of flexible electronics and robots has stimulated interest in the deformation behavior of polymers under liquid environments. In this work, we introduce a “local” method to study the toluene-induced deflection of polydimethylsiloxane (PDMS) plates. Placing a graphite rod on the surface of a PDMS plate, we are able to confine the spreading and evaporation of toluene and the

Abstract. Staggered and linear multi-particle trains constitute characteristic structures in inertial microfluidics. Using lattice-Boltzmann simulations, we investigate their properties and stability, when flowing through microfluidic channels. We confirm the stability of cross-streamline pairs by showing how they contract or expand to their equilibrium axial distance. In contrast, same-streamline

Abstract. Dendrites represent the complicated pattern formation in condensed matter physics and microstructures in materials science. Previous work shows that a dendrite can change its orientation due to a change in the anisotropy of solid-liquid interfacial energy. The anisotropy change is often assumed by the increase in the nominal composition. Here, we consider the case where the interfacial anisotropy

Abstract. The interaction of two dipolar hard spheres near a surface and under the influence of gravity and external perpendicular magnetic fields is investigated theoretically. The full ground-state phase diagram as a function of gravity and magnetic field strengths is established. A dimer (i.e., two touching beads) can only exist when the gravity and magnetic field strengths are simultaneously not

Abstract. Insights on the mechanical behavior in materials highly depend upon sufficiently characterizing microstructure details at the relevant length scales. In this study, the side-branching dynamics of dendritic structures formation in pure substances is studied upon the phase-field simulations of crystallization with applied direct currents. The effect of heat diffusion (including thermoelectric

Abstract. Active matter systems often are well approximated as overdamped, meaning that any inertial momentum is immediately dissipated by the environment. On the other hand, especially for macroscopic systems but also for many mesoscopic ones particle mass can become relevant for the dynamics. For such systems we recently proposed an underdamped continuum model which captures translationally inertial

Abstract. A two-dimensional quantitative cellular automaton (CA) model is employed to simulate dendrite arm fragmentation and dendrite arm coarsening in mushy zones. The phenomenon of dendrite arm fragmentation of an Al-Cu alloy during heating is well represented by the CA simulation, and it is analyzed in detail by comparing the local actual concentration and local equilibrium concentration. The CA

Abstract. The growth of hexagonal columnar dendrite during directional solidification with respect to the multi-controlling parameters such as anisotropy, cooling rate, temperature gradient and orientation angle were investigated by a quantitative phase-field method, respectively. The simulation results show that the increase of anisotropy, cooling rate and temperature gradient can accelerate the solidification

Abstract. Understanding the mechanisms responsible for the formation and growth of FtsZ polymers and their subsequent formation of the Z -ring is important for gaining insight into the cell division in prokaryotic cells. In this work, we present a minimal stochastic model that qualitatively reproduces in vitro observations of polymerization, formation of dynamic contractile ring that is stable for

Abstract. Disease and predation are both highly important in ecology, and pathogens with multiple host species have turned out to be common. Nonetheless, the interplay between multi-host epidemics and predation has received relatively little attention. Here, we analyse a model of a predator-prey system with disease in both prey and predator populations and determine reasonable parameter values using

Abstract. The cohesion of insect swarms has been attributed to the fact that the resultant internal interactions of the swarming insects produce, on the average, a centrally attractive force that acts on each individual. Here it is shown how insect swarms can also be bound together by centrally forces that on the average are repulsive (outwardly directed from the swarm centres). This is predicted to

Abstract. Understanding the charge transfer mechanism through deoxyribonucleic acid (DNA) molecules remains a challenge for numerous theoretical and experimental studies in order to be utilized in nanoelectronic devices. Various methods have attempted to investigate the conductivity of double-stranded (ds-) and single-stranded DNA (ssDNA) molecules. However, different electronic behaviors of these

Abstract. Although there are theoretical predictions (Eur. Phys. J. E 41, 110 (2018)) for the rich-phase behaviour of colloidal cubes mixed with non-adsorbing polymers, a thorough verification of this phase behaviour is still underway; experimental studies on mixtures of cubes and non-adsorbing polymers in bulk are scarce. In this paper, mixtures of hollow silica nanocubes and linear polystyrene in

Abstract. The fluctuation theorem is considered intrinsically linked to reversibility and therefore its phenomenological consequence, the fluctuation relation, is sometimes considered not applicable. Nevertheless here is considered the paradigmatic example of irreversible evolution, the 2D Navier-Stokes incompressible flow, to show how universal properties of fluctuations in systems evolving irreversibily

Abstract. In the present work we report crack patterns formed in aqueous Laponite® gel in a rectangular box, while exposed to a uniform static electric field. The crack pattern shows a very interesting tree-like geometry extending from the positive to the negative electrode. At the positive electrode a large number of cracks appear at first and merge with each other in stages thus forming tree-like

Abstract. The evaporation and crystallization process for sessile saline droplets during depressurization is experimentally studied. The relationship between ambient pressure and the crystallization pattern is primarily discussed. When the ambient pressure is low, salt particles are easily formed at the droplet contact line. In contrast, when the ambient pressure is similar to atmospheric pressure

Abstract. We study how the stability of a homogeneous incompressible fluid flow over a saturated Brinkman porous medium is affected by a change in porosity. We produce neutral curves using the shooting method in the area of bimodality. When the porosity decreases, the topology of these curves changes because of the interplay between two instability modes. The long-wave instability is dominant if the

Abstract. Electron beam additive manufacturing (EBAM) is an emerging additive manufacturing technology with extremely high energy beam. The rapid solidification in the molten pool is of interest but not fully understood. In EBAM, with both large thermal gradient and cooling rate, the microstructure evolution during solidification is difficult to be described. The quantitative multi-phase-field model

Abstract Patterns can form when the uniform state of any system is unstable so that some non-uniform motif grows in amplitude. Here, we identify an alternative way to form non-trivial structures, which we call “ghost-patterns”. Ghost-patterns emerge from noisy initial conditions when all non-uniform modes decay in amplitude except for one non-trivial motif which fails to decay. Hence, in seeking structured

Abstract A two-dimensional model is developed to simulate dendrite growth and movement in a gravity environment. The model combines the features of cellular automaton and lattice Boltzmann methods. Two sets of distribution functions are adopted to calculate the melt flow and solute transport simultaneously. The fluid force acting on the dendrite is calculated by extending the basic flow simulation

Abstract The fission yeast cell is shaped as a very regular cylinder ending by hemi-spheres at both cell ends. Its conserved phenotypes are often used as read-outs for classifying interacting genes and protein networks. Using Pascal and Young-Laplace laws, we proposed a framework where scaling arguments predicted shapes. Here we probed quantitatively one of these relations which predicts that the division

Nonlinear effects on the electrophoresis of a soft particle, consisting of a rigid hydrophobic core coated with a diffuse polymer layer (PEL) suspended in an electrolyte medium, are studied. The impact of the ion partitioning effect arising due to the Born energy difference between the PEL and the electrolyte is approximated based on the equilibrium Boltzmann equation, with which the ion distribution

We perform the phase-field modeling to investigate the growth pattern selections of the complex dendritic structures in constrained growth with different solidification and orientation conditions. The results show that hexagonal close-packed (hcp) crystals emerge as dendritic and cellular arrays in different planes, originating from the specific hcp anisotropy that allows different growth preferences

Nonmechanical fluid pumping principle has been developed utilizing the interactions of both the director [Formula: see text] and velocity v fields and temperature T redistribution across a two-dimensional homogeneously-aligned nematic (HAN) microfluidic channel under the influence both of a heat flux [Formula: see text] and the surface electric field E0, originating from the surface charge density

Fluctuating viscoelasticity for conformation-tensor-based models is studied at equilibrium, in simple-shear deformation, and in uniaxial extension. The models studied are the upper-convected Maxwell model, the FENE-P model with finite chain-extensibility, and the Giesekus model with anisotropic drag. Using numerical simulations, the models are compared in detail both with each other and with analytical

I discuss fluid flow at the interface between solids with anisotropic roughness. I show that the Bruggeman effective medium theory and the critical junction theory give nearly the same results for the fluid flow conductivity. This shows that, in most cases, the surface roughness observed at high magnification is irrelevant for fluid flow problems such as the leakage of static seals, and fluid squeeze-out

We present the results of hydrodynamic simulations using the method of multi-particle collision dynamics for a system of squirmer microswimmers moving under the influence of gravity at low Reynolds numbers. In addition, the squirmers are bottom-heavy so that they experience a torque which aligns them along the vertical. The squirmers interact hydrodynamically by the flow fields of a stokeslet and rotlet

An algorithm is proposed to implement unsteady jump boundary conditions in the lattice Boltzmann method (LBM). This is useful for dealing with problems of mass transfer across membranes that exhibit resistance and discontinuity in concentration. The algorithm is simple to implement into an existing LBM-based code that computes diffusion and advection of a solute. Analytical solutions are recovered

Three recently observed facts of the translocation of actual hexameric and nonstructural (NS) helicases are related to the various physical quantities and are in accordance with the recently proposed mechanical mechanism: a) the translocation of hexameric helicases might be led by either the N-terminal domain (NTD) or C-terminal domain (CTD) depending on which domain has a smaller central pore, b)

The hazards associated with travelling on highways in desert regions arise mainly from wind-borne sand disasters, such as complete or partial burial of the road surface by sand particles, and from erosion of the roadbed by the particles. To simulate the damage process caused by sand particles on roads in the desert, scaled-down tests were performed in a wind tunnel whereby sand particles of differing

Periodic wrinkling of a rigid capping layer on a deformable substrate provides a useful method for templating surface topography for a variety of novel applications. Many experiments have studied wrinkle formation during the compression of a rigid film on a relatively soft pre-strained elastic substrate, and most have focused on the regime where the substrate thickness can be considered semi-infinite

Abstract. An erythrocytes sedimentation rate (ESR) measures how fast a blood sample sediments along a test tube in one hour in a clinical laboratory. Since elevated level of ESR is associated with inflammatory diseases, ESR is one of the routine hematology test in a clinical laboratory. In this paper, the physics of erythrocyte (RBC) sedimentation rate as well as the dynamics of the RBC is explored

Abstract. We study a two-dimensional binary mixture of active and passive colloids as an idealized model of an hybrid aggregate of living cells and inert particles. We perform molecular dynamics simulations of this system using two different thermostats, and we systematically investigate the effect of varying these two effective temperatures on the system behavior, as characterized by its density,

Abstract. A two-dimensional multiphase cellular automaton (CA) model is proposed for the prediction of growth kinetics and microstructural evolution during peritectic transformation of Fe-C alloys. The proposed model is validated by comparing the simulation results with the experimental measurements and analytical predictions for the growth kinetics of the \( \gamma\) -phase and the concentration distributions

A two-dimensional (2-D) cellular automaton-finite difference method (CA-FDM) model and in situ observation experiments of directional solidification using a transparent alloy of SCN-2wt.% ACE are employed to investigate various microstructural evolution of columnar dendrites during directional solidification. In the present model, the growth of columnar dendrites is simulated using a CA technique.

The mechanisms by which interfacial instabilities instigate the growth of solidification patterns is a topic of longstanding interest. In columnar solidification of metallic melts, where the solid-liquid interfacial energy is anisotropic, evolving dendritic patterns compete depending on their relative misorientation. By contrast, organic "plastic crystals", such as alloys based on succinonitrile, where

Self-consistent field theory (SCFT) is a powerful approach for computing the phase behavior of block polymers. We describe a fast version of the open-source Polymer Self-Consistent Field (PSCF) code that takes advantage of the massive parallelization provided by a graphical processing unit (GPU). Benchmarking double-precision calculations indicate up to 30× reduction in time to converge SCFT calculations

We numerically investigate the influence of interfacial deformations on the drag force exerted on a particle straddling a fluid interface. We perform finite element simulations of the two-phase flow system in a bounded two-dimensional geometry. The fluid interface is modeled with a phase-field method which is coupled to the Navier-Stokes equations to solve for the flow dynamics. The interfacial deformations

A capillary tube model reveals that the surface tension at the air-water interface cannot cause the instability of gravity-driven unsaturated slow flow in sandy soils.

This paper deals with the Lehmann rotation of banded cholesteric droplets subjected to a temperature gradient when they coexist with their own isotropic liquid. I show that their angular rotation velocity increases --in absolute value-- when they are subjected to an additional AC electric field in the conducting regime. This velocity increase is correlated with a prolate distortion of the droplets

We study the flocking model introduced by Vicsek et al. (Phys. Rev. Lett. 75, 1226 (1995)) in the "coarsening" regime. At standard self-propulsion speeds, we find two distinct growth laws for the coupled density and velocity fields. The characteristic length scale of the density domains grows as [Formula: see text] (with [Formula: see text] , while the velocity length scale grows much faster, viz.

We derive approximate mean field equations for the fluid flow between elastic solids with randomly rough surfaces including interfacial fluid slip and shear thinning. We present numerical results for the fluid flow and friction factors for realistic systems, in particular, we consider the case of an elastic cylinder with random surface roughness in relative sliding contact with a flat rigid (low-energy)

Environmental temperature has a well-conserved effect on the pulse velocity and excitability of excitable biological systems. The consistency suggests that the cause originates from a fundamental principle. A physical (hydrodynamic) approach has proposed that the thermodynamic state of the hydrated interface (e.g., plasma membrane) determines the pulse behavior. This implies that the temperature effect

Zwitterions are a class of unique molecules that can be modified onto nanomaterials to render them with antifouling properties. Here we report a thorough NMR investigation of dendrimers modified with zwitterions in terms of their structure, hydrodynamic size, and diffusion time in aqueous solution. In this present work, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) were partially decorated

The paper carries on our previous investigations on the complementary version of Purcell's rotator (sPr3): a low-Reynolds-number swimmer composed of three balls of equal radii. In the asymptotic regime of very long arms, the Stokes-induced governing dynamics is derived, and then experimented in the context of energy-minimizing self-propulsion characterized in the first part of the paper.

The microstructural evolution of a SCN-ACE alloy in a temperature gradient is studied by cellular automaton (CA) modeling and in situ experiments. The initially columnar dendrites gradually evolve to a completely solid region with a planar solid/liquid interface. The CA simulations and in situ observations present the migration of secondary dendrite arms and liquid pockets due to temperature gradient

Turbulent wind patterns over a two-dimensional isolated downsized barchan dune under the influence of sinusoidal inflow with different amplitudes and periods are simulated. The evolution rules of wind velocity over time at different positions are revealed. The flow reattachment distance and turbulence intensity distribution are also compared. The results show that wind velocities at different positions

This research proposes a general approach to determine the peculiarity of the interaction between colloidal particles in different liquid crystals. The main idea of this approach is in the definition of the colloidal particle as a source of the possible deformation of the ground state of the director field distribution. The ground state imposes restrictions on possible deformations and determines the

We have studied the dewetting dynamics of partially wetting liquid films confined between a soft elastic hemisphere and an elastomer layer by means of systematic experiments. We focused on the experimentally most relevant case of non-axisymmetric dewetting, which initiated at the locations of minimum film thickness near the perimeter of the contact area. We found the contact line speed to be highly

Abstract. Compared to nanofluids with spherical particles, nanofluids with anisotropic particles possess higher thermal conductivity and present a better enhancement option in heat transfer applications. The viscosity variation of such nanofluids becomes of great importance in evaluating their pumping power in thermal systems. This paper presents a comprehensive review of the experimental and theoretical

The bond orientational order parameters originally introduced by Steinhardt et al. (Phys. Rev. B 28, 784 (1983)) are a common tool for local structure characterization in soft matter studies. Recently, Mickel et al. (J. Chem. Phys. 138, 044501 (2013)) highlighted problems of the bond orientational order parameters due to the ambiguity of the underlying neighbourhood definition. Here we show the difficulties

Rod-shaped active micro/nano-particles, such as bacterial and bipolar metallic micro/nano-motors, demonstrate novel collective phenomena far from the equilibrium state compared to passive particles. We apply a simulation approach --dissipative particle dynamics (DPD)-- to explore the collectively ordered states of self-propelled rods (SPRs). The SPRs are confined in a finite circular zone and repel

Aquaporins (AQPs) are protein channels which facilitate rapid water permeation across cell membrane. The AQPs are very vital for biological organs, as their malfunction causes severe diseases in human body. A particular family of AQPs, that is AQP5, has a significant role in lung fluid transport due to submucosal glands structure. However, it has not been yet well understood whether these protein channels

The correlations detected by the mutual information in the propensities of a molecular viscous liquid are studied by molecular-dynamics simulations. Dynamic heterogeneity is evidenced and two particle fractions with different mobility and relaxation identified. The two fractions exhibit the scaling of their relaxation in terms of the rattling amplitude of the particle trapped in the cage of the first

A particle raft is formed by a layer of small particles floating on a water surface, which has a higher load bearing capacity than pure water. In the present work, we have made a comprehensive study on the wrinkling number and force of the particle raft in planar compression. The wrinkling number during the whole loading process is measured, accompanied with snapshots on the morphologies of the particle

We investigate the component dynamics in asymmetric binary glass formers. Focusing on the dielectric spectra of the high-Tg components m-tricresyl phosphate and quinaldine mixed with toluene as low-Tg component, the broadend spectra cannot be described by Kohlrausch or Cole-Davidson (CD) functions. Instead, we apply a generalized CD function which allows to control the width of the susceptibility independently