The European Physical Journal E最新文献

{"title":"Influence of a thin sheet between domains on dynamics of two-dimensional coalescence in smectic films","authors":"P. V. Dolganov,&nbsp;N. S. Shuravin,&nbsp;V. K. Dolganov","doi":"10.1140/epje/s10189-026-00611-w","DOIUrl":"10.1140/epje/s10189-026-00611-w","url":null,"abstract":"<div><p>Two-dimensional coalescence of holes (regions with thickness less than the surrounding film) in free-standing Smectic <i>A</i> films was studied. Investigations were made on two types of domains: circular holes and holes with a thin sheet of the external film between holes. Direct evidence was found that before start of coalescence a long, thin sheet of external film can exists between holes. This sheet determines the early mechanism of coalescence. It is shown that the existence of the sheet essentially elongates the linear temporal dependence of the size of the bridge connecting the two holes <i>r</i>_<i>b</i>(<i>t</i>) ~ <i>t</i>. Later when the thin sheet disappears the crossover to the conventional dependence <i>r</i>_<i>b</i>(<i>t</i>) ~ (<i>t</i>)^1/2 was observed. Our results can explain numerous data on two-dimensional and quasi-two-dimensional coalescence at the early and later stages of coalescence.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><img></picture></div><div><p>Linear dependence of the size of the bridge between two coalescing domains on time <i>r</i>_<i>b</i>(<i>t</i>) ~ (<i>t</i>) can be related to existence of a thin sheet between coalescing domains. Asymmetric coalescence demonstrates the influence of the thin sheet on coalescence dynamics</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148663320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effective mobilities for thin-film flows on micropillar arrays","authors":"Raphael Saiseau,&nbsp;Stefan Karpitschka","doi":"10.1140/epje/s10189-026-00615-6","DOIUrl":"10.1140/epje/s10189-026-00615-6","url":null,"abstract":"<p>Micropillar-textured surfaces provide versatile platforms for controlling wetting, imbibition, and droplet dynamics, and also serve as model systems for engineered textured surfaces used in applications ranging from thermal management and microfluidics to semiconductor processing. While spontaneous hemiwicking in such geometries has been extensively studied, a unified framework for thin-film modeling that captures both capillary-driven and Marangoni-driven transport across arbitrary film thicknesses has remained lacking. Here, we derive explicit analytical mobility expressions for lubrication-based modeling of wetting dynamics on periodic micropillar arrays. Using an equivalent microchannel formulation and a Fourier series solution of the Stokes equations, we obtain exact mobilities for both pressure-driven and Marangoni-driven flows, valid for film thicknesses both below and above the pillar height. The resulting formulation captures the interplay between film thickness, pillar height, and the lateral confinement scale, and connects confined transport, overtopped films, and effective slip behavior within a single framework. In particular, Marangoni-driven transport exhibits a stronger saturation with increasing pillar height than pressure-driven transport once lateral confinement dominates. These mobility laws recover known hemiwicking limits and provide the constitutive ingredient needed to extend lubrication theory to complex wetting dynamics on textured substrates.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00615-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148628589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of swelling gradients and evaporation dynamics in polymer brushes using high-resolution colorimetry","authors":"Vincent Siekman,&nbsp;Sander Reuvekamp,&nbsp;Enqing Liu,&nbsp;Sissi de Beer,&nbsp;Frieder Mugele","doi":"10.1140/epje/s10189-026-00613-8","DOIUrl":"10.1140/epje/s10189-026-00613-8","url":null,"abstract":"<p>We present a white-light interferometry method enabling real-time, full-field measurement of local film thickness with nanometer vertical resolution using a simple optical microscopy set-up. We apply this approach to investigate droplet-induced swelling and vapor-infused deswelling of poly(lauryl methacrylate) (PLMA) brushes in contact with <i>n</i>-alkanes (<i>C</i>12, <i>C</i>14, <i>C</i>16), spanning two orders of magnitude in vapor pressure. For uniformly pre-swollen brushes, we demonstrate that evaporation is governed by vapor-phase transport rather than transport within the brush, remaining remarkably constant over swelling ratios from 4.2 to 1.6. Rescaling time by vapor pressure collapses all deswelling data onto a single master curve, consistent with diffusion-limited gas-phase transport. For droplet-induced swelling on initially dry brushes, we quantify the coupled effects of imbibition, evaporation, and condensation on the formation of swelling halos. More volatile solvents produce faster-growing halos that reach a limited lateral extent in open air. The final width follows from a balance between near-constant liquid influx and size-dependent evaporative outflow. Temporal swelling profiles collapse onto a common functional form, indicating universal behavior governed by solvent transport and evaporation. These results establish colorimetric interferometry as an accessible tool for probing dynamic soft interfaces and a means to constrain key model parameters, notably the grafting density <span>(sigma )</span> and the interaction parameter <span>(chi )</span>, enabling systematic extraction of material properties from dynamic experiments.</p><p>Schematic illustration of a swelling gradient (“halo”) emerging after placing an alkane drop onto aninitially dry PLMA polymer brush. The spatiotemporal evolution of the halo region is monitored usingwhite-light colorimetry (inset, top view), enabling quantitative conversion of interference colors intolocal brush thickness </p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00613-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel numerical method for simulating a droplet in a Leidenfrost state on soft substrates","authors":"Chen Miao,&nbsp;Florian Kummer","doi":"10.1140/epje/s10189-026-00606-7","DOIUrl":"10.1140/epje/s10189-026-00606-7","url":null,"abstract":"<p>This work presents a numerical framework for three-phase systems (liquid, gas, visco-elastic solid) using an extended discontinuous Galerkin (XDG) and level-set method. It simulates complex fluid–structure interactions with heat and mass transfer, maintaining strictly sharp phase interfaces without artificial smoothing. After verifying optimal convergence via a fluid–solid Taylor–Couette benchmark, the framework is applied to the Leidenfrost effect. While existing studies typically assume rigid solid surfaces, we investigate deformations induced by localized vapor pressure on soft substrates. We validate quasi-static droplet shapes against existing rigid solid models and derive a novel analytical extension for soft substrates using a Winkler foundation model. Our simulations demonstrate excellent agreement with this new analytical solution. Finally, the framework’s robustness is demonstrated by simulating a Leidenfrost droplet sliding down an inclined soft substrate, successfully capturing asymmetric droplet shape, substrate deformation and localized interfacial waves.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00606-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148589471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identifying equilibration pathways beyond the (alpha )-relaxation: distinguishing the slow Arrhenius process from the Johari–Goldstein relaxation","authors":"Chiara Di Leva,&nbsp;Federico Caporaletti","doi":"10.1140/epje/s10189-026-00605-8","DOIUrl":"10.1140/epje/s10189-026-00605-8","url":null,"abstract":"<p> Equilibration in liquids and glasses can proceed through multiple pathways, mediated by relaxation processes that remain active even when structural <span>(alpha )</span>-relaxation is strongly suppressed. Two prominent candidates are the Johari–Goldstein (JG) relaxation and the recently discovered slow Arrhenius process (SAP), both of which persist in the glassy state and exhibit a weaker temperature dependence than the structural relaxation. Their coexistence raises a central challenge: how to identify which localized process governs a given nonequilibrium kinetics. Here we compare the microscopic signatures of these two mechanisms and discuss practical strategies for their attribution. In particular, we argue that activation-energy matching provides only a first empirical indication, whereas SAP-driven kinetics can be identified more stringently within the collective small displacement (CSD) framework. The JG-controlled kinetics, on the contrary, should be assessed through consistency criteria tied to thermodynamic state of the system and <span>(alpha )</span>-dynamics. We believe that establishing such discriminating frameworks will be crucial for the next generation of experiments, simulations, and theoretical descriptions of nonequilibrium glassy dynamics.\u0000</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148547539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Lévy walks to Brownian motion in schools of zebrafish (Danio rerio)","authors":"Andreza M. da Silva,&nbsp;Francisco C. B. Leal,&nbsp;Pabyton G. Cadena,&nbsp;Viviane M. de Oliveira,&nbsp;Adauto J. F. de Souza,&nbsp;Antonio R. de C. Romaguera,&nbsp;Anderson L. R. Barbosa","doi":"10.1140/epje/s10189-026-00602-x","DOIUrl":"10.1140/epje/s10189-026-00602-x","url":null,"abstract":"<div><p>Population density strongly affects the internal organization and movement dynamics of fish schools. Here, we investigate density-dependent collective motion in zebrafish (<i>Danio rerio</i>) schools with group sizes ranging from 2 to 30 individuals. Using trajectories measured relative to the school center of mass, we show that individual motion is superdiffusive at low densities and progressively approaches Brownian-like behavior as density increases. Step-length distributions are well described by truncated power laws: for <span>(N le 15)</span>, the fitted exponents are compatible with a Lévy-walk regime, whereas larger groups show a transition toward Brownian motion. In parallel, <i>q</i>-Gaussian fits of the signed radial displacement increments reveal heavy-tailed, non-Gaussian fluctuations at low densities and a gradual convergence toward Gaussian-like behavior at high densities. These results support a density-driven transition from a polarized, strongly correlated schooling state to a more disordered shoaling state, suggesting that increased density reorganizes local interactions within the group.</p></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13388639/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148534901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetics of droplet cloaking and wetting ridge growth on lubricated polymer brushes","authors":"Antonio Torregrosa Abellán,&nbsp;Enqing Liu,&nbsp;Vincent Siekman,&nbsp;Frieder Mugele,&nbsp;Friederike Schmid,&nbsp;Rodrique G. M. Badr","doi":"10.1140/epje/s10189-026-00607-6","DOIUrl":"10.1140/epje/s10189-026-00607-6","url":null,"abstract":"<p>We investigate the kinetics of wetting ridge growth and droplet cloaking on lubricant-infused polymer brushes using a combination of experiments, molecular dynamics simulations, and theoretical modeling. We focus on three representative systems: DMSO-water on hexadecane-swollen PLMA (D-H), water on hexadecane-swollen PLMA (W-H), and water on PDMS (W-S). The dynamics are governed by the interplay between interfacial thermodynamics, brush elasticity, and transport of lubricant within the brush. Ridge growth is accompanied by the formation of depletion zones both beneath and outside the drop. This leads to a progressive slowdown governed by the need to transport lubricant through the brush. At sufficiently high swelling, we observe local separation of oil from the brush within the ridge, providing an additional mechanism for lubricant depletion. To rationalize these observations, we develop a continuum diffusion model based on the free energy of the brush and its coupling to the contact line. The model quantitatively captures the growth of the wetting ridge at intermediate and late times, demonstrating that the kinetics are largely controlled by diffusive transport within the brush.\u0000</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13381383/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Curved fibers in turbulent channel flow","authors":"Darish Jeswin Dhas,&nbsp;Cristian Marchioli","doi":"10.1140/epje/s10189-026-00609-4","DOIUrl":"10.1140/epje/s10189-026-00609-4","url":null,"abstract":"<p>We investigate how breaking the geometric axisymmetry of fibers alters their dynamics when suspended in wall turbulence, using intrinsic curvature as a controlled proxy for symmetry loss. The study is based on a series of large-scale direct numerical simulations of turbulent channel flow laden with flexible fibers with varying lengths and intrinsic curvatures. We find that curved fibers tend to accumulate in the near-wall region of the flow. Analyzing their orientation dynamics, we recorded a marked shift in dynamics in comparison to their straight counterparts as they tend to have a preferential alignment even in the near-isotropic region of the flow. They also tend to tumble at larger rates with increasing curvatures. Furthermore, we also find that fiber dynamics become less sensitive to their curvature with increasing length.\u0000</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13385021/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148534907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tunable wetting properties of poly(3-hexylthiophene) films with different doping levels","authors":"Junqi Lu,&nbsp;David Neusser,&nbsp;David Moser,&nbsp;Pedro M. Resende,&nbsp;Christopher R. McNeill,&nbsp;Sabine Ludwigs","doi":"10.1140/epje/s10189-026-00608-5","DOIUrl":"10.1140/epje/s10189-026-00608-5","url":null,"abstract":"<div><p>This work systematically investigates the wetting properties of electrochemically doped poly(3-hexylthiophene) (P3HT) films at different oxidation states. In situ spectroelectrochemistry and ex situ opto-electronic characterization of the doped films confirm that the polaron and bipolaron states have successfully been obtained through electrochemical doping. Sessile drop and dynamic water contact angle measurements yield reproducible results that strongly depend on the applied electrochemical doping potential, with a maximum water contact angle variation of up to 43° from the neutral to the fully doped state. The evolution of wettability correlates with the doping states and is heavily influenced by morphological changes upon doping. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) reveal that wrinkle-like structures appear at high doping levels which is consistent with predominant bipolaron formation accompanied by doping-induced swelling followed by drying. Complementary grazing-incidence wide-angle X-ray scattering (GIWAXS) shows that doping to the polaronic state leads to lamellar expansion with a contraction of the <i>π</i>–<i>π</i> stacking distance within crystalline domains. Despite these lattice changes, the edge-on orientation is largely preserved, indicating that the overall crystalline texture remains stable even at the highest studied doping levels.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Electrochemically doped films show large differences in wettability due to surface morphology changes upon strong doping, while conductivity values remain high.</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00608-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148459065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the fluorescence lifetime changes of a solvatochromic aurone probe dye upon wetting in an emissive polymer brush matrix by deconvolution of TCSPC data","authors":"Jonah L. Decker,&nbsp;Sören Steup,&nbsp;Sergey I. Druzhinin,&nbsp;Heiko Ihmels,&nbsp;Holger Schönherr","doi":"10.1140/epje/s10189-026-00597-5","DOIUrl":"10.1140/epje/s10189-026-00597-5","url":null,"abstract":"<div><p>The wetting processes of polymer brushes, embedded with a fluorescent probe, were investigated with time-correlated single photon counting. A suitable aurone dye was synthesized, which exhibits moderate fluorescence in aprotic solvents, poor fluorescence in protic solvents and practically no fluorescence in aqueous solution. Poly(diethylene glycol methyl ether methacrylate) (PDEGMA) brushes of ca. 200 nm thickness were obtained by polymerization from a Ti surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The dye-loaded brushes show fluorescence of the dye comparable with the autofluorescence of the PDEGMA brushes and the subjacent α-bromoisobutyryl bromide (BiBB) functionalized polydopamine (PDA) layer. With a global analysis of fluorescence decays, the lifetimes of the complex multicomponent materials were deconvoluted. The dry polymer loaded with the dye possesses a five-exponential fluorescence decay with the characteristic decay times of ~ 3.0 ns for the dye, and ~ 6.0, 1.8 and 0.45 ns for PDEGMA brushes as well as &lt; 0.05 ns for the PDA-BiBB layer. Because of the strong decrease of the fluorescence lifetime of the dye down to ~ 2.4 ns when submersed in water and a concomitant decrease of the lifetimes of the matrix to 4.5, 1.3 and 0.40 ns, both dye and matrix fluorescence are feasible reporter probes for the analysis of wetting processes of polymers with fluorescence lifetime imaging. The contrast of the intensity images of the aurone, which is low because of background fluorescence, increases by a factor of 3.1 in the time-resolved imaging at certain time delay after excitation. Hence, the incorporation of the aurone in the polymer brushes is a promising and versatile system for the investigation of (de)wetting dynamics employing fluorescence lifetime imaging and nanosecond time-resolved fluorescence imaging microscopy.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Incorporation of a fluorescent dye in polymer brushes allows monitoring of (de)wetting dynamics with time-resolved fluorescence imaging microscopy</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00597-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148459113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}