ALT Controlling the folding of biopolymers in crowded and confined environments, such as the interior of biological cells, remains a significant challenge. Macromolecular crowding and spatial confinement can strongly influence transition pathways between folded and unfolded states of proteins. Such environments can be mimicked in experiments by confining polymers within soft, tunable media, such as hydrogels – cross-linked polymer networks that swell by absorbing solvent and exhibit stimulus-dependent responsiveness. Here, we develop a self-consistent mean-field theory for the equilibrium swelling and internal composition of a hydrogel immersed in a solution of free polymer coils. The theory extends the Flory-Rehner framework by incorporating free polymer coils, modeled as fluctuating ellipsoids, whose sizes and shapes are characterized by the eigenvalues of the gyration tensor. Confinement of the coils within gel pores is characterized by an effective free-volume fraction, parametrized fr

ALT Inferring constitutive laws from transient response data is a central inverse problem in soft condensed-matter physics, particularly when the relevant relaxation spectrum extends beyond the time window of a single experiment. Time-temperature superposition (TTS) constrains this problem for thermorheologically simple materials in the linear viscoelastic regime by allowing temperature to rescale the characteristic relaxation time without changing the underlying shape of the relaxation spectrum. We incorporate this constraint into a physics-informed machine-learning framework for time-resolved mechanical spectroscopy via chirp rheometry. We encode compact fractional viscoelastic models as causal convolutional features derived from the Boltzmann superposition principle, and we jointly fit multi-temperature chirp records using sparse variational Gaussian process regression. The model infers horizontal shift factors, constitutive parameters, and an observational-noise scale directly from tim

ALT We investigate the field-directed assembly of patchy colloidal particles composed of magnetic hematite cubes encapsulated in TPM shells. These Pacman-like particles exhibit specific interactions via their magnetic patch, enabling tunable structures under external fields. A magnetic field drives patch-to-patch interactions, while an AC electric field induces stacking and spreading. By using this multi-field combination and by varying field parameters, such as frequency and amplitude, we achieve programmable transitions between distinct assembly modes. Our work offers a versatile platform for designing reconfigurable colloidal architectures with potential applications in micro-robotics and smart materials.

ALT Many solvated materials, from nanoparticles to polyelectrolytes, acquire charge through the dissociation or association of surface groups, a phenomenon known as charge regulation (CR). Recent methods use hybrid charge regulation Monte Carlo (CR-MC)/molecular dynamics (MD) to evolve the system while dynamically adjusting charges on the surface groups. However, this approach is computationally expensive, as Monte Carlo sampling can be as costly as the accompanying MD. In this work, we introduce charge regulation machine learning (CR-ML), a graph attention network that predicts the ionization probability of every surface site from the instantaneous configuration, the dissociation constant of surface groups, and the solution conditions. We show that CR-ML reproduces the equilibrium conformations and degree of ionization obtained with CR-MC for a hydrophobic polyanion. We further test CR-ML on the more complex system of two nanoparticles mediated by a polyelectrolyte, where it accurately pr

ALT Understanding the microscopic behavior of materials in response to mechanical perturbations is a central challenge in soft matter, yet existing methods, which typically rely on microscopy-based imaging, often struggle with spatial heterogeneity and low signal-to-noise that are characteristic of many soft and biological materials. Additionally, many existing rheo-optical methods focus on the response to macro-scale forces rather than localized perturbations despite the importance of local stresses in biological and industrial applications of soft materials. Here, we present STroboscopically Averaged, time-Resolved Differential Dynamic Microscopy (starDDM) to investigate a sample's deformation across time and distance due to a cyclically applied local force. As proof-of-principle, we use this model-independent and tracer-free approach to map the motions of active cytoskeleton composites imposed by the movement of an optically trapped probe particle embedded within the complex network. We

ALT Various types of electrohydrodynamic instabilities in liquid crystals (LCs) are a recurring theme in LC research. The nonlinear stage of the flexoelectric instability in nematics remains the least studied aspect of this phenomenon. This work highlights a key advancement in nonlinear physics, providing a compelling example of nonlinear dynamical system behavior. By solving the system of nonlinear equations for a nematic in an alternating external field, we derive from first principles the unique "dancing" behavior of truly two-dimensional patterns above the flexoelectric instability threshold. Our analysis is restricted to liquid crystals with negative dielectric permittivity and electrical conductivity anisotropies. The resulting solution represents a stable limit cycle near above the Hopf bifurcation, valid within the parameters range where the solutions characteristic exponent is complex. The generalized two-dimensional Ginzburg-Landau-like phenomenological theory of the phenomenon i

ALT Biomedical devices, wearable interfaces, and soft robots require compliant soft materials with reliable mechanical performance, yet the molecular principles needed to design such materials are not always fully understood. Thus, there is an urgent need to understand how to design novel stretchable and soft hydrogels with enhanced toughness, i.e. resistance to breakage. Slide-ring gels (SRGs) are a class of unconventional soft materials formed by polyrotaxanes (PR) building blocks whereby sliding cyclodextrins (CD) replace traditional chemical and physical crosslinks and in turn enhance toughness and stretchability by several orders of magnitude. The rational design of SRGs re- mains challenging due to a lack of a mechanistic understanding of the role played by individual components. In this work, we implement simple synthetic perturbations that individually target polymer-CD and CD-CD interactions in unstoppered pseudopolyrotaxanes (pPR) solutions and measure the consequent changes in v

ALT Collective decision-making requires individuals to reconcile diverse, often conflicting opinions to reach a common course of action. However, within a group, they rarely exert equal influence, leading to non-reciprocal communication patterns manifested as leader-follower relationships and social hierarchies. Here, using homing pigeon flocks as a model system, we develop a trajectory-based framework to infer and quantify hierarchy within navigating living collectives. We find that while small flocks exhibit pronounced hierarchy, increasing flock size progressively weakens it, driving the collection toward more egalitarian decision-making. We provide a physical basis of this observation using a thermodynamic framework in which non-reciprocal communication between birds carries an information-entropy cost. Our calculations reveal that hierarchy weakening observed in larger flocks is a direct consequence of maintaining a constant per-individual entropy production rate across flock sizes. T

ALT Improving the particle surface frictional behavior is of considerable importance in several industries so as to manipulate the powder flowability and handling. In this work, we have studied the lubrication phenomena in an assembly of flowing bulk powder particles in presence of a fine powder lubricant. Experiments were conducted in two different shear environments, for two different levels of confinement and using three different bulk powder particles having distinct surface morphology. The added lubricant particles tend to adhere to the surface of bulk particles thereby altering their surface morphology. This results in altered inter-particle friction, which typically reduces for small addition of lubricant, but increases on its excess addition, thereby altering the particle flowability. While this behavior is generally understood through previous studies, the current work explores how the effect of confinement, shear environment and particle surface characteristics combine in a uniqu

ALT Chemical reactions can sustain polymer motion without necessarily generating the compression required for buckling. Theory and simulations show that tension-dependent chemical transitions coupled to bond elasticity generate finite-wavelength traveling strain waves in a semiflexible polymer. In the straight chain at fixed axial span, the waves reduce mean active contraction while leaving mean elastic tension unchanged, generating compression that drives bending above a threshold. Releasing the mean load allows longitudinal waves to persist while transverse perturbations decay.

ALT We present a phenomenological, mean-field model for condensates of intrinsically disordered proteins that describes inverse phase transitions and qualitatively predicts reentrant phase behavior as a function of salt concentration. The model is based on a matrix-based formulation of the Flory-Huggins free energy, in which the enthalpic interaction parameter and the protein valence, defined here as the number of effective "sticky patches", are treated as free parameters. Its central insight is that integrating out dynamics of fast-moving molecular species generates an effective entropic force that increases the free-energy barrier to mixing, even within a mean-field description. We account for this by linking Gaussian integration of co-solutes to the Schur complement of the matrix-based Flory-Huggins free energy. This provides a general thermodynamic framework illustrating how enthalpic interactions that increase the number of available microstates necessarily induce effective entropic f

ALT In sheared aggregating suspensions, flow drives both the formation and breakage of particle clusters, whose dynamic evolution influences transport and rheological properties. Understanding these mechanisms remains challenging due to the complex interplay between interparticle forces, hydrodynamic interactions, and shear flow. Using parallelized Accelerated Stokesian Dynamics (PASD) simulations, we investigate cluster microstructure and rotational dynamics, and how their coupling produces suspension stress in sheared, attractive non-Brownian suspensions. When interparticle attraction dominates over separating shear forces, clusters grow until mechanical loading balances maximum interparticle bond strength. We examine how the cluster stresslet depends on cluster size, with both quantities normalized by their mechanical yielding scales. Scaled cluster stresslets collapse onto a master curve exhibiting three distinct regimes: cubic, quadratic, and linear with respect to the scaled radius o

ALT Non-destructive early detection of water stress is critical for precision agriculture, yet current detection methods are often labor-intensive or destructive. We propose a rapid, non-invasive method based on Spectral Submanifold (SSM) reduction to analyze the nonlinear vibration dynamics of soybean plants. Unlike traditional linear modal analysis, our data-driven approach reveals a distinct transition in the dominant dynamics of the plant stem as drought progresses. Specifically, we uncover a sign reversal in the nonlinear damping coefficient within SSM-reduced models of full plants. Our finding reveals a fundamental transition in the plant's dissipative mechanics from a pressurized, fluid-rich vessel exhibiting superlinear (viscoelastic) damping to a dry, cellular solid dominated by sublinear (frictional) damping. This transition is closely correlated with the onset of physiological stress indicated by a significant decrease in the values of mature-leaf soil plant analysis development

ALT We study the response of compressible microtubule-based active fluids to sinusoidally varying activity patterns, using experiments and theory. Microtubules accumulate in low-activity regions and are depleted from high activity ones, with the density difference controlled by the wavelength of the activity pattern. To explain these observations the continuum model needs to account for both active stresses that are proportional to nematic order tensor and the isotropic active pressure. At short wavelengths, active vortices spanning adjacent high and low activity regions suppress density modulation. At larger wavelengths, vortical flows confined to the low or high activity region allow for the emergence of the density contrast. Our work shows that a minimal theoretical model of active compressible fluids accurately reproduces experiments, while elucidating the fundamental constraints on control protocols that seek to tame their chaotic dynamics.

ALT Macroscopic phase segregation in binary active mixtures can emerge solely from clutter noise: local, composition-dependent stochasticity, without repulsion or anti-alignment torques. Using an agent-based Vicsek model, we show that clutter noise alone destabilizes the mixed state, producing multi-stripe, co-moving band, and metastable counter-propagating morphologies, as well as a stable phase-segregated polar fluid. Our hydrodynamic theory shows that clutter noise suppresses local polar order and transport efficiency, consistent with the demixing observed in the agent-based model.

ALT Polymerized membranes are paradigmatic fluctuating systems in which geometry, elasticity, and statistical fluctuations combine to produce anomalous long-distance behavior. In the disorder-free flat phase, bending rigidity increases at long wavelengths while in-plane elastic moduli soften. Quenched random metric and curvature introduce competing thermal and disorder-induced fluctuations. We review perturbative and nonperturbative field-theoretical approaches to these systems, from pure membranes to their disordered counterparts. Early one-loop studies identified a disorder-free fixed point, P₄, and a zero-temperature disorder-dominated fixed point, P₅. A subsequent nonperturbative renormalization-group analysis revealed a third fixed point, Pc, at finite temperature and disorder, governing a continuous wrinkling transition between the thermally dominated flat phase and a disorder-dominated glassy phase. Higher-order perturbative calculations also recover a Pc-like fixed point, with anom

ALT When an obstacle moves through a compressible medium, it creates a density perturbation. Theoretical arguments regarding the shape of this density wake in Brownian suspensions either suppose infinite dilution or describe only the far field. Here, we study via experiments and numerical simulations the closing of the density perturbation just behind a circular obstacle in dense 2D suspensions of particles that are thermal or self-propelled. In the thermal case, we show that the characteristic length of the wake is a non-monotonic function of density, decreasing then increasing. We rationalise the scalings of both regimes by analytical arguments that highlight the role of the compressibility factor of the suspension. Based on this new understanding of the passive case, we show that the influence of self-propulsion observed in experiments and simulations can be understood as if the obstacle is effectively larger in an active bath, with non-trivial and distinct roles of the self-propulsion

ALT Airborne transmission of biological matter is likely to cause numerous respiratory distress in coastal populations during certain harmful algal blooms. While we know that dissolved algal toxins aerosolize, the contribution of particle-associated toxins is still unknown. The observation of microalgae in the atmosphere suggests that cells or cell debris could be a carrier. Exchange of particulate matter between ocean and atmosphere is driven by sea spray: microplastics and bacteria aerosolize in jet droplets, following the bursting of air bubbles. However, current models for particle capture only consider surface effects, which fail to explain how large microalgal cells (5-50 um) can be entrapped in jet drops (100-800 um). Here, we demonstrate with a variety of species that microalgae are consistently captured in jet drops, and derive a new particle capture model based on the hydrodynamics of the jet. Using the enrichment factor, which measures the increase in concentration in the first

ALT Molecular modelling of electrochemical systems at larger than atomic scales poses particular challenges, not least the ability to represent correct thermodynamic, hydrodynamic and dielectric properties while still being computationally viable for large scale applications. In the case of aqueous electrolytes such as those used in vanadium-based batteries with oxidation-reduction (redox) reactions, both a background medium that can respond to localised electric fields due to high-valence ions and control over ion transport properties are crucial to embed consistently in the model. To this end, we propose the use of Dissipative Particle Dynamics (DPD) combined with a newly-devised highly coarse-grained polarisable water model with pairwise interactions designed to produce realistic thermodynamic behaviour as the basis for the aqueous electrolytes found in vanadium redox flow batteries (VRFB). We consider how the core water model can be modified to incorporate the ionic species found in VR

ALT We study cyclic shear in a lattice elastoplastic model of amorphous materials. The model displays a threshold shear amplitude γc, which increases with sample annealing. For imposed amplitudes γ₀≤sssimγc, it shows slow progression to an absorbing elastic state. For γ₀gtrsim γc, it shows slow fatigue and delayed material failure. Our key contribution is to elucidate a mechanistic understanding of this behaviour. We show that progression to an absorbing state maps to single element diffusion on a finite interval with two absorbing boundaries. We derive expressions for the decay rate of the fraction of active elements, and the survival distribution. The diffusing variable is the local elemental strain, which takes two jumps stroboscopically per cycle. Once the value at any site diffuses below its yielding threshold, the element behaves elastically. This leads to a gradual accumulation of strains just below threshold. For γ₀≤sssim γc this diffusive behaviour is preceded by many cycles in wh