M. E. Cates's research while affiliated with University of Cambridge and other places
What is this page?
This page lists the scientific contributions of an author, who either does not have a ResearchGate profile, or has not yet added these contributions to their profile.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
Publications (286)
Interfaces of phase-separated systems roughen in time due to capillary waves. Because of fluxes in the bulk, their dynamics is nonlocal in real space and is not described by the Edwards-Wilkinson or Kardar-Parisi-Zhang (KPZ) equations, nor their conserved counterparts. We show that, in the absence of detailed balance, the phase-separated interface...
Classical Nucleation Theory (CNT), linking rare nucleation events to the free-energy landscape of a growing nucleus, is central to understanding phase-change kinetics in passive fluids. Nucleation in nonequilibrium systems is much harder to describe because there is no free energy, but instead a dynamics-dependent quasipotential that typically must...
Classical nucleation theory (CNT), linking rare nucleation events to the free energy landscape of a growing nucleus, is central to understanding phase-change kinetics in passive fluids. Nucleation in non-equilibrium systems is much harder to describe because there is no free energy, but instead a dynamics-dependent quasi-potential that typically mu...
This corrects the article DOI: 10.1103/PhysRevLett.127.068001.
In passive fluid-fluid phase separation, a single interfacial tension sets both the capillary fluctuations of the interface and the rate of Ostwald ripening. We show that these phenomena are governed by two different tensions in active systems, and compute the capillary tension σcw which sets the relaxation rate of interfacial fluctuations in accor...
In passive fluid-fluid phase separation, a single interfacial tension sets both the capillary fluctuations of the interface and the rate of Ostwald ripening. We show that these phenomena are governed by two different tensions in active systems, and compute the capillary tension $\sigma_{cw}$ which sets the relaxation rate of interfacial fluctuation...
The probability of trajectories of weakly diffusive processes to remain in the tubular neighborhood of a smooth path is given by the Freidlin-Wentzell-Graham theory of large deviations. The most probable path between two states (the instanton) and the leading term in the logarithm of the process transition density (the quasipotential) are obtained...
We study the dynamics of quasi-two-dimensional concentrated suspensions of colloidal particles in active gels by computer simulations. Remarkably, we find that activity induces a dynamic clustering of colloids even in the absence of any preferential anchoring of the active nematic director at the particle surface. When such an anchoring is present,...
Suspensions of spherical active particles often show microphase separation. At a continuum level, coupling their scalar density to fluid flow, there are two distinct explanations. Each involves an effective interfacial tension: the first mechanical (causing flow) and the second diffusive (causing Ostwald ripening). Here we show how the negative mec...
At the surfaces of autophoretic colloids, slip velocities arise from local chemical gradients that are many-body functions of particle configuration and activity. For rapid chemical diffusion, coupled with slip-induced hydrodynamic interactions, we deduce the chemohydrodynamic forces and torques between colloids. For bottom-heavy particles above a...
Suspensions of spherical active particles often show microphase separation. At a continuum level, coupling their scalar density to fluid flow, there are two distinct explanations. Each involves an effective interfacial tension: the first mechanical (causing flow) and the second diffusive (causing Ostwald ripening). Here we show how the negative mec...
At the surfaces of autophoretic colloids, slip velocities arise from local chemical gradients that are many-body functions of particle configuration and activity. For rapid chemical diffusion, coupled with slip-induced hydrodynamic interactions, we deduce the chemohydrodynamic forces and torques between colloids. Near a no-slip wall, the forces can...
We numerically investigate the behavior of a phase-separating mixture of a blue phase I liquid crystal with an isotropic fluid. The resulting morphology is primarily controlled by an inverse capillary number, χ, setting the balance between interfacial and elastic forces. When χ and the concentration of the isotropic component are both low, the blue...
We investigate numerically the behaviour of a phase-separating mixture of a blue phase I liquid crystal with an isotropic fluid. The resulting morphology is primarily controlled by an inverse capillary number, $\chi$, setting the balance between interfacial and elastic forces. When $\chi$ and the concentration of the isotropic component are both lo...
Colloidal heat engines extract power out of a fluctuating bath by manipulating a confined tracer. Considering a self-propelled tracer surrounded by a bath of passive colloids, we optimize the engine performances based on the maximum available power. Our approach relies on an adiabatic mean-field treatment of the bath particles which reduces the man...
Active fluids are a class of nonequilibrium systems where energy is injected into the system continuously by the constituent particles themselves. Many examples, such as bacterial suspensions and actomyosin networks, are intrinsically chiral at a local scale, so that their activity involves torque dipoles alongside the force dipoles usually conside...
We demonstrate that active rotations in chemically signalling particles, such as autochemotactic $\textit{E. coli}$ close to walls, create a route for pattern formation based on a nonlinear yet deterministic instability mechanism. For slow rotations, we find a transient persistence of the uniform state, followed by a sudden formation of clusters co...
This article is part of the themed issue ‘Soft interfacial materials: from fundamentals to formulation’.
We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid-crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time $\tau_C$. To explore the resulting interplay between active and polymeric dynamics, we first generalise a linear stability analysis (from earlier studies without...
We consider a continuum model of active viscoelastic matter, whereby a model of an active nematic liquid-crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time tC. To explore the resulting interplay between active and polymeric dynamics, we first generalise a linear stability analysis (from earlier studies wit...
We demonstrate that the formation of bicontinuous emulsions stabilized by
interfacial particles (bijels) is more robust when nanoparticles rather than
microparticles are used. Emulsification via spinodal demixing in the presence
of nearly neutrally wetting particles is induced by rapid heating. Using
confocal microscopy, we show that nanospheres al...
Pressure is the mechanical force per unit area that a confined system exerts
on its container. In thermal equilibrium, it depends only on bulk properties
(density, temperature, etc.) through an equation of state. Here we show that in
a wide class of active systems the pressure depends on the precise interactions
between the active particles and the...
Active Brownian particles (ABPs) and Run-and-Tumble particles (RTPs) both
self-propel at fixed speed $v$ along a body-axis ${\bf u}$ that reorients
either through slow angular diffusion (ABPs) or sudden complete randomisation
(RTPs). We compare the physics of these two model systems both at microscopic
and macroscopic scales. Using exact results fo...
A paradigm for internally driven matter is the active nematic liquid crystal,
whereby the equations of a conventional nematic are supplemented by a minimal
active stress that violates time reversal symmetry. In practice, active fluids
may have not only liquid crystalline but also viscoelastic polymer degrees of
freedom. Here we explore the resultin...
Cell motility in higher organisms (eukaryotes) is crucial to biological functions ranging from wound healing to immune response, and also implicated in diseases such as cancer. For cells crawling on hard surfaces, significant insights into motility have been gained from experiments replicating such motion in vitro. Such experiments show that crawli...
Pressure is the mechanical force per unit area that a confined system exerts
on its container. In thermal equilibrium, the pressure depends only on bulk
properties (density, temperature, etc.) through an equation of state. Here we
show that in active systems containing self-propelled particles, the pressure
instead can depend on the precise interac...
We study by computer simulations the dynamics of a droplet of passive, isotropic fluid, embedded in a polar active gel. The latter represents a fluid of active force dipoles, which exert either contractile or extensile stresses on their surroundings, modelling for instance a suspension of cytoskeletal filaments and molecular motors. When the polari...
We have measured the spatial distribution of motile Escherichia coli inside
spherical water droplets emulsified in oil. At low cell concentrations, the
cell density peaks at the water-oil interface; at increasing concentration, the
bulk of each droplet fills up uniformly while the surface peak remains.
Simulations and theory show that the bulk dens...
Colloidal particles dispersed in liquid crystals can form new materials with tunable elastic and electro-optic properties. In a periodic 'blue phase' host, particles should template into colloidal crystals with potential uses in photonics, metamaterials and transformational optics. Here we show by computer simulation that colloid/cholesteric mixtur...
A consensus is emerging that discontinuous shear thickening (DST) in dense
suspensions marks a transition from a flow state where particles remain well
separated by lubrication layers, to one dominated by frictional contacts. We
show here that reasonable assumptions about contact proliferation predict two
distinct types of DST in the absence of ine...
We present a simulation study of pattern formation in an ensemble of chemotactic run-and-tumble bacteria, focussing on the effect of spatial confinement, either within traps or inside a maze. These geometries are inspired by previous experiments probing pattern formation in chemotactic strains of E. coli under these conditions. Our main result is t...
In bacteria, regulatory proteins search for a specific DNA binding target via
"facilitated diffusion": a series of rounds of 3D diffusion in the cytoplasm,
and 1D linear diffusion along the DNA contour. Using large scale Brownian
dynamics simulations we find that each of these steps is affected differently
by crowding proteins, which can either be...
We simulate colloids (radius R∼1 μm) trapped at the interface between a cholesteric liquid crystal and an immiscible oil at which the helical order (pitch p) in the bulk conflicts with the orientation induced at the interface, stabilizing an ordered array of disclinations. For a weak anchoring strength W of the director field at the colloidal surfa...
We present computer simulations of the response of a flexoelectric blue phase network, either in bulk or under confinement, to an applied field. We find a transition in the bulk between the blue phase I disclination network and a parallel array of disclinations along the direction of the applied field. Upon switching off the field, the system is un...
Glassy polymers show "strain hardening": at constant extensional load, their flow first accelerates, then arrests. Recent experiments under such loading have found this to be accompanied by a striking dip in the segmental relaxation time. This can be explained by a minimal nonfactorable model combining flow-induced melting of a glass with the build...
Active Brownian particles (ABPs, such as self-phoretic colloids) swim at
fixed speed $v$ along a body-axis ${\bf u}$ that rotates by slow angular
diffusion. Run-and-tumble particles (RTPs, such as motile bacteria) swim with
constant $\u$ until a random tumble event suddenly decorrelates the
orientation. We show that when the motility parameters dep...
We present Brownian dynamics simulations of the facilitated diffusion of a protein, modeled as a sphere with a binding site on its surface, along DNA, modeled as a semiflexible polymer. We consider both the effect of DNA organization in three dimensions and of sequence heterogeneity. We find that in a network of DNA loops, which are thought to be p...
We simulate macroscopic shear experiments in active nematics and compare them with microrheology simulations where a spherical probe particle is dragged through an active fluid. In both cases we define an effective viscosity: in the case of bulk shear simulations this is the ratio between shear stress and shear rate, whereas in the microrheology ca...
We study the behaviour of confined cubic blue phases under shear flow via
lattice Boltzmann simulations. We focus on the two experimentally observed
phases, blue phase I and blue phase II. The disinclination network of blue
phase II continuously breaks and reforms under shear, leading to an oscillatory
stress response in time. The oscillations are...
We simulate an experiment in which a colloidal probe is pulled through an
active nematic fluid. We find that the drag on the particle is non-Stokesian
(not proportional to its radius). Strikingly, a large enough particle in
contractile fluid (such as an actomyosin gel) can show negative viscous drag in
steady state: the particle moves in the opposi...
Microbiology is the science of microbes, particularly bacteria. Many bacteria are motile: they are capable of self-propulsion. Among these, a significant class execute so-called run-and-tumble motion: they follow a fairly straight path for a certain distance, then abruptly change direction before repeating the process. This dynamics has something i...
Adding a nonadsorbing polymer to passive colloids induces an attraction between the particles via the "depletion" mechanism. High enough polymer concentrations lead to phase separation. We combine experiments, theory, and simulations to demonstrate that using active colloids (such as motile bacteria) dramatically changes the physics of such mixture...
We present a computer simulation study, via lattice Boltzmann simulations, of a microscopic model for cytoplasmic streaming in algal cells such as those of Chara corallina. We modelled myosin motors tracking along actin lanes as spheres undergoing directed motion along fixed lines. The sphere dimension takes into account the fact that motors drag v...
Glassy polymers show strain hardening: at constant extensional load, their
flow first accelerates, then arrests. Recent experiments have found this to be
accompanied by a striking and unexplained dip in the segmental relaxation time.
Here we explain such behavior by combining a minimal model of flow-induced
liquefaction of a glass, with a descripti...
![FIG. 1: [Color online.] (a) Interparticle elastic potential as a...](profile/Juho-Lintuvuori/publication/221745731/figure/fig2/AS:667682672218134@1536199362667/Color-online-a-Interparticle-elastic-potential-as-a-function-of-reduced-separation_Q320.jpg)
![FIG. 2: [Color online.] (a-d) Snapshots of a steadily rotating dimer...](profile/Juho-Lintuvuori/publication/221745731/figure/fig3/AS:667682672234505@1536199362698/Color-online-a-d-Snapshots-of-a-steadily-rotating-dimer-over-a-translation-of-half-a_Q320.jpg)
We study by simulation the physics of two colloidal particles in a
cholesteric liquid crystal with tangential order parameter alignment at the
particle surface. The effective force between the pair is attractive at short
range and favors assembly of colloid dimers at specific orientations relative
to the local director field. When pulled through th...
We present large scale computer simulations of the nonlinear bulk rheology of
lamellar phases (smectic liquid crystals) at moderate to large values of the
shear rate (Peclet numbers 10-100), in both two and three dimensions. In two
dimensions we find that modest shear rates align the system and stabilise an
almost regular lamellar phase, but high s...
Recently, we proposed a theoretical framework to include thermal fluctuations into the Lattice Boltzmann (LB) method for non-ideal fluids. Here, we apply a variant thereof to a certain class of force-based non-ideal fluid LB models. We find that ideal-gas-like noise is an exact result of the fluctuation-dissipation theorem in the hydrodynamic regim...
We report new results from our programme of molecular dynamics simulation of hard-sphere systems, focusing on crystallization and glass formation at high concentrations. First we consider a much larger system than hitherto, N = 86 400 equal-sized particles. The results are similar to those obtained with a smaller system, studied previously, showing...
Active gels or active liquid crystals are soft materials which are driven out of equilibrium by their continuum use of chemical energy. Physical realisations of active gels are solutions of cytoskeletal filaments with molecular motors, and concentrated suspensions of bacterial swimmers. Here we focus on the active nematic phase which is exhibited b...
We report simulations of a continuum model for (apolar, flow aligning) active
fluids in two dimensions. Both free and anchored boundary conditions are
considered, at parallel confining walls that are either static or moving at
fixed relative velocity. We focus on extensile materials and find that steady
shear bands, previously shown to arise ubiqui...
We report large scale simulations of the blue phases of cholesteric liquid crystals. Our results suggest a structure for blue phase III, the blue fog, which has been the subject of a long debate in liquid crystal physics. We propose that blue phase III is an amorphous network of disclination lines, which is thermodynamically and kinetically stabili...
We propose a hybrid lattice Boltzmann algorithm to simulate the hydrodynamics
of colloidal particles inside a liquid crystalline host. To validate our
algorithm, we study the static and the microrheology of a colloid in a nematic,
with tangential anchoring of the director field at the particle surface, and we
confirm theories and experiments showin...
We present a systematic analysis of the phase diagram of a defect in an active polar fluid, found by means of Lattice Boltzmann simulations. We show that for rod-like active particles, extensile activity favours spirals and contractile activity favours asters. Polarity on the other hand introduces "self-advection terms" which can change the relativ...
The discrete Boltzmann equation for both the ideal and a non-ideal fluid is
extended by adding Langevin noise terms in order to incorporate the effects of
thermal fluctuations. After casting the fluctuating discrete Boltzmann equation
in a form appropriate to the Onsager-Machlup theory of linear fluctuations, the
statistical properties of the noise...
We study a model of self propelled particles exhibiting run and tumble
dynamics on lattice. This non-Brownian diffusion is characterised by a random
walk with a finite persistence length between changes of direction, and is
inspired by the motion of bacteria such as E. coli. By defining a class of
models with multiple species of particle and transm...
We report experiments on hard sphere colloidal glasses that reveal a type of
shear banding hitherto unobserved in soft glasses. We present a scenario that
relates this to an instability arising from shear-concentration coupling, a
mechanism previously thought unimportant in this class of materials. Below a
characteristic shear rate $\dot\gamma_c$ w...
Concentrated particulate suspensions, commonplace in the pharmaceutical, cosmetic and food industries, display intriguing rheology. In particular, the dramatic increase in viscosity with strain rate (shear thickening and jamming), which is often observed at high-volume fractions, is of practical and fundamental importance. Yet, manufacture of these...
We introduce thermal fluctuations in the lattice Boltzmann method for nonideal fluids. A fluctuation-dissipation theorem is derived within the Langevin framework and applied to a specific lattice Boltzmann model that approximates the linearized fluctuating Navier-Stokes equations for fluids based on square-gradient free-energy functionals. The obta...
We simulate a colloidal particle (radius R) in a cholesteric liquid crystal (pitch p) with tangential order parameter alignment at the particle surface. The local defect structure evolves from a dipolar pair of surface defects (boojums) at small R/p to a pair of twisted disclination lines wrapping around the particle at larger values. On dragging t...
Lattice Boltzmann simulations have become a method of choice to solve the hydrodynamic equations of motion of a number of complex fluids. Here we review some recent applications of lattice Boltzmann to study the hydrodynamics of liquid crystalline materials. In particular, we focus on the study of (a) the exotic blue phases of cholesteric liquid cr...
We introduce thermal fluctuations in the lattice Boltzmann method for non-ideal fluids. With the help of the continuum kinetic theory of non-ideal fluids, a fluctuation-dissipation theorem is derived within the Langevin framework. Results are applied to a specific lattice Boltzmann model that approximates the linearized fluctuating Navier-Stokes eq...
We simulate by lattice Boltzmann the nonequilibrium steady states of run-and-tumble particles (inspired by a minimal model of bacteria), interacting by far-field hydrodynamics, subject to confinement. Under gravity, hydrodynamic interactions barely perturb the steady state found without them, but for particles in a harmonic trap such a state is qui...
We present a generic mechanism by which reproducing microorganisms, with a diffusivity that depends on the local population density, can form stable patterns. For instance, it is known that a decrease of bacterial motility with density can promote separation into bulk phases of two coexisting densities; this is opposed by the logistic law for birth...
We present extensive numerical studies to determine the phase diagrams of cubic and hexagonal blue phases in an electric field. We confirm the earlier prediction that hexagonal phases, both two and three dimensional, are stabilized by a field, but we significantly refine the phase boundaries, which were previously estimated by means of a semianalyt...
We study a class of zero-range processes in which the real-space condensation
phenomenon does not occur and is replaced by a saturated condensation: that is,
an extensive number of finite-size "condensates" in the steady state. We
determine the conditions under which this occurs, and investigate the dynamics
of relaxation to the steady state. We id...
We study by molecular dynamics the interplay between arrest and crystallization in hard spheres. For state points in the plane of volume fraction (0.54 <or= varphi <or= 0.63) and polydispersity (0 <or= s <or= 0.085), we delineate states that spontaneously crystallize from those that do not. For noncrystallizing (or precrystallization) samples we fi...
The run-and-tumble dynamics of bacteria, as exhibited by \textit{E. coli}, offers a simple experimental realization of non-Brownian, yet diffusive, particles. Here we present some analytic and numerical results for models of the ideal (low-density) limit in which the particles have no hydrodynamic or other interactions and hence undergo independent...
Here we review a hybrid lattice Boltzmann algorithm to solve the equations of
motion of cholesteric liquid crystals. The method consists in coupling a
lattice Boltzmann solver for the Navier-Stokes equation to a finite difference
method to solve the dynamical equations governing the evolution of the liquid
crystalline order parameter. We apply this...
The `soft glassy rheology' (SGR) model gives an appealing account of the flow of nonergodic soft materials in terms of the local yield dynamics of mesoscopic elements. Newtonian, power-law, and yield-stress fluid regimes arise on varying a `noise temperature', x. Here we extend the model, to capture the idea that the noise is largely caused by yiel...
We study numerically the rheological properties of a slab of active gel close to the isotropic-nematic transition. The flow behavior shows a strong dependence on the sample size, boundary conditions, and on the bulk constitutive curve, which, on entering the nematic phase, acquires an activity-induced discontinuity at the origin. The precursor of t...
We use lattice Boltzmann simulations to investigate the formation of arrested structures upon demixing of a binary solvent containing neutrally wetting colloidal particles. Previous simulations for symmetric fluid quenches pointed to the formation of "bijels": bicontinuous interfacially jammed emulsion gels. These should be created when a glassy mo...
We consider self-propelled particles undergoing run-and-tumble dynamics (as exhibited by E. coli) in one dimension. Building on previous analyses at drift-diffusion level for the one-particle density, we add both interactions and noise, enabling discussion of domain formation by "self-trapping," and other collective phenomena. Mapping onto detailed...
We present an accurate method to include arbitrary singular distributions of forces in the lattice Boltzmann formulation of hydrodynamics. We validate our method with several examples involving Stokeslet, stresslet, and rotlet singularities, finding excellent agreement with analytical results. A minimal model for sedimenting particles is presented...
We report hybrid lattice Boltzmann (HLB) simulations of the hydrodynamics of an active nematic liquid crystal sandwiched between confining walls with various anchoring conditions. We confirm the existence of a transition between a passive phase and an active phase, in which there is spontaneous flow in the steady state. This transition is attained...
We simulate by the lattice Boltzmann method the steady shearing of a binary fluid mixture with full hydrodynamics in three dimensions. Contrary to some theoretical scenarios, a dynamical steady state is attained with finite correlation lengths in all three spatial directions. Using large simulations, we obtain at moderately high Reynolds numbers ap...
Active liquid crystals or active gels are soft materials which can be physically realised, e.g. by preparing a solution of cytoskeletal filaments interacting with molecular motors. We study the hydrodynamics of an active liquid crystal in a slab-like geometry with various boundary conditions, by solving numerically its equations of motion via latti...
We present a second virial theory of the isotropic-to-nematic phase transition in solutions of (polydisperse) wormlike micelles interacting via a hard-core excluded volume. Analytical expressions are derived for the osmotic pressures and the chemical potentials of the surfactant molecules in the coexisting phases. In systems where the mean micelle...
We study theoretically the effect of adsorbed homopolymer on surfactant bilayers. We formulate the energy of adsorption per unit area as a Taylor series in curvature for both spherical and cylindrical surfaces. In the limits of weak adsorption analytic expressions are derived for the polymeric contribution to the elastic moduli of the bilayer, usin...
We consider a simple model for the dielectric response of a water-rich surfactant sponge phase (L3), in which an insulating bilayer separates two continuous brine domains ("in" and "out"). Experiments of Vinches, Coulon and Roux (J. Phys. II, 4 (1994) 1165) show for high salt concentrations a bimodal relaxation. We associate their higher-frequency...
We study the statistics of a grafted polymer brush, consisting of a set of monodisperse chains in solution, each attached irreversibly by one end to a flat surface. We use a self-consistent field method, valid in the limit of weak excluded volume and at moderately high surface coverage. Exploiting the fact that the chains are highly stretched, we m...
We study the role played by harmonic corrections to the order parameter in the Landau-Ginzburg description of the transition from an isotropic to a weakly ordered state, and find two further stable structures in the phase diagram (face-centred cubic and square) in addition to the usual three crystalline phases (body-centred cubic, hexagonal and lam...
We show that a solution of f-armed star polymers develops a peak in its scattering structure function S(q), whose height scales as f3/2. The peak is largest when the separation between neighboring stars is about equal to the radius of a star. Our results follow from general scaling properties of polymers in a good solvent. We predict crystalline or...
We study a schematic mode-coupling model in which the ideal glass transition is cut off by a decay of the quadratic coupling constant in the memory function. (Such a decay, on a time scale tau I , has been suggested as the likely consequence of activated processes.) If this decay is complete, so that only a linear coupling remains at late times, th...
Certain lyotropic surfactant systems, including microemulsions, from smectic phases at very low volume fractions of surfactant (in the few percent range). Upon further dilution these melt into an isotropic state. The effect of a steady shear flow on this transition has been considered from the point of view of time-dependent Landau Ginzburg theory....
We have studied the behaviour of mixtures of lyotropic lamellar phases and submicron-size
solid particles under shear. Two different lamellar phases were used—an oil-swollen
system (SDS, dodecane, pentanol, water) with sterically-stabilised PMMA particles, and an
aqueous system (AOT, brine) with charged-stabilised polystyrene particles. Under shea...
The late-stage phase ordering, in d = 2 dimensions, of symmetric fluid
mixtures violates dynamical scaling. We show however that, even at
50/50 volume fractions, if an asymmetric droplet morphology is
initially present then this sustains itself, throughout the viscous
hydrodynamic regime, by a "coalescence-induced coalescence"
mechanism. Scaling i...
We consider the growth of a polymer layer
on a flat surface in a good solvent by in situ polymerization. This is
viewed
as a modified form of diffusion-limited aggregation without branching.
We predict theoretically the formation of
a pseudo-brush with density (z) ∝ z−2/3
and characteristic height H ∝ t3.
These results are found by combining a mean...
Recent progress in the understanding of yielding and jamming of colloids, based on extensions of the mode coupling theory
(MCT) of glasses, is reviewed. This includes schematic extensions to shear-thickening fluids based on the ad-hoc introduction
of a stress-dependent vertex in MCT. The possible distinction between dynamic and static yield stress,...
In multi-component lipid membranes, phase separation can lead to the formation of domains. The morphology of fluid-like domains has been rationalized in terms of membrane elasticity and line tension. We show that the morphology of solid-like domains is governed by different physics, and instead reflects the molecular ordering of the lipids. An unde...
We quantify, within mode coupling theory, how changes in the liquid structure affect that of the glass. Apart from the known sensitivity to the structure factor S(q) at wave vectors around the first sharp diffraction peak q0, we find a strong (and inverted) response to structure at wave vectors below this peak: an increase in S(q0/2) lowers the deg...
Extended mode-coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular "ideal glass transition" present in the standard mode-coupling theory where such couplings are ignored. We suggest here that, rather than allowing for activated processes as sometimes supposed, contributions from current-density co...
Citations
... As such, in recent years, numerous studies have sought to characterize the dynamics of the interface. This has been done by examining the stability of growing tissue fronts under different conditions [22][23][24][25] or by ascertaining the scaling behavior of the interface roughness to determine the universality class to which the growth process belongs [26][27][28][29][30][31]. Importantly, these studies led to conflicting results, leaving the question of the dynamics of growing tissue fronts and their stability unsettled. ...
... It is, therefore, natural that field theories that aim to describe the behaviour of active matter have to revisit the foundations and need to go beyond the detailed-balance restrictions. Successive works culminated in the recently introduced, so-called Active Model B+ (AMB+) [53][54][55], that attracted a lot of interest lately [56][57][58][59]. Continuum approaches, very recently, have also been extended to include active chirality and specifically account for broken-time reversal symmetries [36,60,61]. ...
... Nardini et al. [43] suggest that F represents the passive forces, whereas λ and ζ represent the continuous dissipation characteristic of active matter. This theory exhibits novel patterned microphases [44,49], critical point properties [50], nucleation kinetics [51] and many-body correlations [52]. Ultimately, a key strength of field theories is their utility in connecting the top-level system phenomenology with an underlying (though possibly hypothetical) physics, enabling the comparing and contrasting of different systems with only coarse information. ...
![[object Object]](https://i1.rgstatic.net/ii/profile.image/1121573775904773-1644415434858_Q64/Elsen-Tjhung.jpg)
![[object Object]](https://i1.rgstatic.net/ii/profile.image/272401191665671-1441956914007_Q64/Cesare-Nardini.jpg)
... An analogous correspondence also exists for stochastic processes, where most-probable paths in a potential V correspond to Hamiltonian trajectories in an effective potential −|∇V| 2 [16,17] and much of the formalism can be carried over [18]. Action-minimization methods to find the most probable path through higher-dimensional potentials have been developed [19][20][21][22][23][24]. The majority of previous work has focused on determining the infinite-time paths, and hence average transition rates. ...
![[object Object]](https://i1.rgstatic.net/ii/profile.image/855647532883968-1581013677150_Q64/Lukas-Kikuchi.jpg)
![[object Object]](https://i1.rgstatic.net/ii/profile.image/1004314403274759-1616458621944_Q64/Ronojoy-Adhikari-2.jpg)
... The presence of active particles in complex and crowded environments, even when intermixed with passive particles, has garnered significant interest, as emphasized in the comprehensive review by Bechinger et al. [36]. Particularly, active components influence the system by generating hydrodynamic interactions (HIs) as they move within the fluid medium [37][38][39][40][41][42][43], resulting in intricate many-body dynamic couplings among particles, a facet that has received relatively less attention. For example, Takatori et al. reported phase-separation experiments on a binary mixture of active actomyosin and passive lipid membrane [25]. ...
... The most common realizations of such systems involve spherical and rod-like particles, for which a plethora of individual and collective phenomena have been documented both theoretically and experimentally. Examples include rheotaxis [7,8,9,10,11], gravitaxis [12,13,14], dynamical clustering and self-assembly [15,16,17,18,19,20,21,22]. Recent studies have explored particles with more intricate shapes, such as fore-aft asymmetric catalytic particles [23,24] used for the collection and degradation of microplastics [25], rotating chiral particle [26,27], phoretic wind turbines [28] and pumps [29,30], shaped-programmed microtori for particle transport [31], L-shaped swimmers following circular orbits [32], tadpole-shaped catalytic swimmers with shape-programmed trajectories [33,34], phoretic fibers and sheets whose motion is modulated by dynamic deformations [35,36,37,38], and diamond-like photocatalytic particles [39]. ...
... where k = |k| is the modulus of the wave vector in the Fourier space. The structure factor is [5,34] S(k, t) = ⟨ρ(k, t)ρ(−k, t)⟩ k , ...
![[object Object]](https://i1.rgstatic.net/ii/profile.image/277634161365027-1443204550589_Q64/Juho-Lintuvuori.jpg)
... This procedure requires a faithful mathematical description of the complete experimental system to which the coarse-graining shall be applied, which might not be available in the case of a bacterial heat bath. Theoretical work often resorts to the (questionable) limit of weak bath-probe coupling [17,18] and yields viscoelastic probe dynamics with a friction kernel and a (generally non-Gaussian [19]) noise with multiple time-scales. It leaves the practitioner somewhat puzzled with regard to its experimental implications. ...
![[object Object]](https://i1.rgstatic.net/ii/profile.image/11431281092333404-1666790546801_Q64/Etienne-Fodor-2.jpg)
... The study of assemblies of active synthetic units-such as molecules 16 , polymers [17][18][19][20] and sheets 21 , is only a recently growing area of research. Some experimental realisations of such systems have been achieved by using external sources of driving such as electro-magnetic actuation [22][23][24][25][26][27] . This kind of external driving mechanism stands in contrast to active and living systems, in which the internal chemistry drives the system out-of-equilibrium. ...
... The steady state motility patterns are notable, because they encompass a transition between translational and rotational motion at higher activity. This transition was not previously observed in single 3D active nematic droplets: there, tangential anchoring leads to only rotation, while helical trajectories are only observed when including chiral contributions, either in the free energy [12,36] or in the stress tensor [37]. As further increasing activity yields chaotic dynamics, this double emulsion provides a remarkable example of a simple active matter system with a particularly rich dynamical behaviour. ...
