The European Physical Journal E最新文献

Thermally activated membrane transformations such as lipid exchange, pore formation, and domain growth are commonly described in terms of activation barriers; yet, the molecular origins of their kinetics often remain difficult to establish. Recent results on interfacial lipid exchange, analyzed using the collective small displacements (CSD) framework originally developed for glass-forming systems, suggest that experimentally accessible thermodynamic observables can become predictive of activation energies and kinetic timescales. These findings raise the possibility that certain membrane remodeling processes remain quantitatively linked to equilibrium membrane thermodynamics. This future-horizon article explores how such thermodynamic-kinetic correspondences might extend beyond interfacial lipid exchange to a broader range of membrane phenomena. We discuss experimental and theoretical opportunities for testing these ideas in systems including pore nucleation, domain growth, transbilayer transport, dewetting, and membrane asymmetry. Particular emphasis is placed on identifying which classes of membrane transformations may exhibit such thermodynamic-kinetic correspondences and under which conditions these descriptions are expected to remain valid. This perspective outlines a possible roadmap for assessing the scope and limitations of predictive thermodynamic descriptions of membrane remodeling processes and for determining when equilibrium thermodynamic properties can provide quantitative access to membrane kinetics.

Thermodiffusion, or the Soret effect, designates a diffusive motion of particles driven by a temperature gradient, leading to a build-up of a concentration gradient. This effect is here measured in the liquid state on the eutectic alloy (textrm{Ag}_{60}textrm{Cu}_{40}), which shows negligible excess volume. No significant thermodiffusion was observed using both in situ X-ray radiography or ex situ energy-dispersive X-ray spectroscopy on separately solidified parts of the sample. This is in contrast to the significant Soret coefficients observed in molten Ag–Al and Al–Ni. Molecular dynamics simulations of thermodiffusion in liquid Ag–Cu [Sarder et al., Philos. Mag. 99, 468–491 (2019)] report significantly stronger thermodiffusion. However, the trend that thermodiffusion in liquid Ag–Cu is weaker than in other liquid alloys like Al–Ni is supported by our experiment.

Different microscopic wall models are frequently used in simulations of confined active Brownian particles (ABPs), but their practical equivalence for standard steady-state observables is rarely assessed against an analytical benchmark with explicit and reproducible criteria. In this work, we present a reproducible benchmark for three common wall models in confined ABPs simulations—stochastic hard, specular hard, and exponential soft—using the analytical hard-wall theory of Duzgun and Selinger as reference. After validating the soft wall against the Boltzmann limit at (text {Pe}=0), we compare density and polarization profiles across (text {Pe}in {1,ldots ,10}) using local and integrated error metrics. The stochastic wall consistently matches the analytical reference best, the specular rule fails sharply in polarization, and the exponential wall’s fidelity depends strongly on both activity and observable; reducing its range improves local but not integrated agreement. A compact two-wall channel test confirms this ranking survives finite confinement. The results provide an explicit, observable-dependent criterion for selecting wall models in ABP simulations.

Benchmarking stochastic, specular, and soft exponential wall models for confined active Brownian particles reveals an observable-dependent fidelity to hard-wall theory

On the occasion of the 25th anniversary of The European Physical Journal E—Soft Matter and Biological Physics, we reflect on the journal’s origins, rooted in Pierre-Gilles de Gennes’ vision of soft matter as a unifying field of physics, and trace its evolution to encompass biological and active systems. We review EPJE’s current position as a journal combining strong European roots with global reach, publishing original research, topical issues, reviews, and experimentally focused Tips and Tricks papers. Looking ahead, we outline our vision: deepening coverage of non-equilibrium and active matter, expanding into functional soft materials, reinforcing our strength in rheology, prioritizing experimental innovation, and embracing sustainability-related research, while remaining committed to Open Access and to bridging generations of scientists in the field.

The non-linear mechanics of amorphous polymers near the glass transition reveals a stress-induced acceleration of stress relaxation of nano-metric sub-units. Recent theoretical work predicts that the local acceleration within these nano-domains should scale as the exponential of the squared local stress, a behavior now supported by experiments. However, this local dynamics has some complex consequences on the macroscopic mechanical response, as dynamical heterogeneities generate complex stress and strain fields in polymers close to the glass transition. In this study we consider the nonlinear creep of an amorphous polymer near its glass transition and evaluate the relation between local and global acceleration and the emerging load-carrying structure, by comparing experimental data with predictions of three models of increasing complexity: a two-state (2S) model, a self-consistent (SC) model and a finite element (FEM) model. The experimentally observed trend of accelerated creep under increasing applied stress is reproduced by the SC and FEM models, while the 2S model overestimates stress localization. The macroscopic, homogenized acceleration is predicted to be close to the microscopic one, albeit with an apparent yield stress that depends on compliance. The FEM model evidences the development of a load-carrying substructure that occupies a small fraction of the total material volume driven by the interaction of sub-domains. This work shows that complexity and heterogeneity emerge due to nonlinear interactions and that their adequate representation is essential for predicting the macroscopic mechanical response of amorphous polymers near their glass transition.

We consider a rigid spherical particle suspended in a binary fluid mixture in the one-phase region near the demixing critical point, assuming the critical composition far from the particle. The particle surface is assumed to interact with mixture components via short-range forces, which can generate the adsorption layer rich in the preferred component and can influence the force exerted on the particle. Applying hydrodynamics based on a coarse-grained free-energy density, we calculate the linear response of the particle velocity to an oscillating external force. We devise a procedure for calculating the first four terms in the low-frequency expansion of the dissipative part of the hydrodynamic force exerted on the particle. We numerically show that the preferential adsorption (PA) changes the coefficients of the four terms, which determine the leading and the next-to-leading terms in the long-time expansion of the particle’s velocity correlation function at equilibrium. The temporal exponents of these terms are not changed by PA. According to our numerical results, the back-flow effects on the first two terms in the low-frequency expansion cancel each other out and PA does not affect the coefficient of the leading term, which is consistent with the previous results obtained in the framework of the Gaussian model. The coefficient of the next-to-leading term can be changed by PA. This change is in the direction of suppressing the correlation for a neutrally buoyant particle.