The European Physical Journal E最新文献

{"title":"Programming tunable active dynamics in a self-propelled robot","authors":"Somnath Paramanick,&nbsp;Arnab Pal,&nbsp;Harsh Soni,&nbsp;Nitin Kumar","doi":"10.1140/epje/s10189-024-00430-x","DOIUrl":"10.1140/epje/s10189-024-00430-x","url":null,"abstract":"<p>We present a scheme for producing tunable active dynamics in a self-propelled robotic device. The robot moves using the differential drive mechanism where two wheels can vary their instantaneous velocities independently. These velocities are calculated by equating robot’s equations of motion in two dimensions with well-established active particle models and encoded into the robot’s microcontroller. We demonstrate that the robot can depict active Brownian, run and tumble, and Brownian dynamics with a wide range of parameters. The resulting motion analyzed using particle tracking shows excellent agreement with the theoretically predicted trajectories. Later, we show that its motion can be switched between different dynamics using light intensity as an external parameter. Intriguingly, we demonstrate that the robot can efficiently navigate through many obstacles by performing stochastic reorientations driven by the gradient in light intensity towards a desired location, namely the target. This work opens an avenue for designing tunable active systems with the potential of revealing the physics of active matter and its application for bio- and nature-inspired robotics.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141086409","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":"Inertial active harmonic particle with memory induced spreading by viscoelastic suspension","authors":"F. Adersh,&nbsp;M. Muhsin,&nbsp;M. Sahoo","doi":"10.1140/epje/s10189-024-00424-9","DOIUrl":"10.1140/epje/s10189-024-00424-9","url":null,"abstract":"<p>We investigate the self-propulsion of an inertial active particle confined in a two-dimensional harmonic trap. The particle is suspended in a non-Newtonian or viscoelastic suspension with a friction kernel that decays exponentially with a time constant characterizing the memory timescale or transient elasticity of the medium. By solving the associated non-Markovian dynamics, we identify two regimes in parameter space distinguishing the oscillatory and non-oscillatory behavior of the particle motion. By simulating the particle trajectories and exactly calculating the steady-state probability distribution functions and mean square displacement; interestingly, we observe that with an increase in the memory time scale, the effective temperature of the environment increases. As a consequence, the particle becomes energetic and spread away from the center, covering larger space inside the confinement. On the other hand, with an increase in the duration of the activity, the particle becomes trapped by the harmonic confinement.</p><p>Schematic diagram of the research problem. Self-propulsion of an inertial active particle in a two dimensional harmonic well subjected to a viscoelastic environment</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140943376","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":"Droplet motion driven by humidity gradients during evaporation and condensation","authors":"Hernán Barrio-Zhang,&nbsp;Élfego Ruiz-Gutiérrez,&nbsp;Daniel Orejon,&nbsp;Gary G. Wells,&nbsp;Rodrigo Ledesma-Aguilar","doi":"10.1140/epje/s10189-024-00426-7","DOIUrl":"10.1140/epje/s10189-024-00426-7","url":null,"abstract":"<p>The motion of droplets on solid surfaces in response to an external gradient is a fundamental problem with a broad range of applications, including water harvesting, heat exchange, mixing and printing. Here we study the motion of droplets driven by a humidity gradient, i.e. a variation in concentration of their own vapour in the surrounding gas phase. Using lattice-Boltzmann simulations of a diffuse-interface hydrodynamic model to account for the liquid and gas phases, we demonstrate that the droplet migrates towards the region of higher vapour concentration. This effect holds in situations where the ambient gradient drives either the evaporation or the condensation of the droplet, or both simultaneously. We identify two main mechanisms responsible for the observed motion: a difference in surface wettability, which we measure in terms of the Young stress, and a variation in surface tension, which drives a Marangoni flow. Our results are relevant in advancing our knowledge of the interplay between gas and liquid phases out of thermodynamic equilibrium, as well as for applications involving the control of droplet motion.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11089009/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140911227","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":"Structure–property modeling of coumarins and coumarin-related compounds in pharmacotherapy of cancer by employing graphical topological indices","authors":"Sujata T. Timmanaikar,&nbsp;Sakander Hayat,&nbsp;Sunilkumar M. Hosamani,&nbsp;Shabana Banu","doi":"10.1140/epje/s10189-024-00427-6","DOIUrl":"10.1140/epje/s10189-024-00427-6","url":null,"abstract":"<p>Coumarins, a subgroup of colorless and crystalline oxygenated heterocyclic compounds originally discovered in the plant Dipteryx odorata, were the subject of a recent study investigating their quantitative structure–activity relationship (QSAR) in cancer pharmacotherapy. This study utilized graph theoretical molecular descriptors, also known as topological indices, as a numerical representation method for the chemical structures embedded in molecular graphs. These descriptors, derived from molecular graphs, play a pivotal role in quantitative structure–property relationship (QSPR) analysis. In this paper, intercorrelation between the Balban index, connective eccentric index, eccentricity connectivity index, harmonic index, hyper Zagreb index, first path Zagreb index, second path Zagreb index, Randic index, sum connectivity index, graph energy and Laplacian energy is studied on the set of molecular graphs of coumarins. It is found that the pairs of degree-based indices are highly intercorrelated. The use of these molecular descriptors in structure–boiling point modeling was analyzed. Finally, the curve-linear regression between considered molecular descriptors with physicochemical properties of coumarins and coumarin-related compounds is obtained.\u0000</p><p>Some of the coumarin-related anti-cancer compounds considered in this study </p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140908034","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":"Asymptotic analysis of particle cluster formation in the presence of anchoring sites","authors":"Paul C. Bressloff","doi":"10.1140/epje/s10189-024-00425-8","DOIUrl":"10.1140/epje/s10189-024-00425-8","url":null,"abstract":"&lt;p&gt;The aggregation or clustering of proteins and other macromolecules plays an important role in the formation of large-scale molecular assemblies within cell membranes. Examples of such assemblies include lipid rafts, and postsynaptic domains (PSDs) at excitatory and inhibitory synapses in neurons. PSDs are rich in scaffolding proteins that can transiently trap transmembrane neurotransmitter receptors, thus localizing them at specific spatial positions. Hence, PSDs play a key role in determining the strength of synaptic connections and their regulation during learning and memory. Recently, a two-dimensional (2D) diffusion-mediated aggregation model of PSD formation has been developed in which the spatial locations of the clusters are determined by a set of fixed anchoring sites. The system is kept out of equilibrium by the recycling of particles between the cell membrane and interior. This results in a stationary distribution consisting of multiple clusters, whose average size can be determined using an effective mean-field description of the particle concentration around each anchored cluster. In this paper, we derive corrections to the mean-field approximation by applying the theory of diffusion in singularly perturbed domains. The latter is a powerful analytical method for solving two-dimensional (2D) and three-dimensional (3D) diffusion problems in domains where small holes or perforations have been removed from the interior. Applications range from modeling intracellular diffusion, where interior holes could represent subcellular structures such as organelles or biological condensates, to tracking the spread of chemical pollutants or heat from localized sources. In this paper, we take the bounded domain to be the cell membrane and the holes to represent anchored clusters. The analysis proceeds by partitioning the membrane into a set of inner regions around each cluster, and an outer region where mean-field interactions occur. Asymptotically matching the inner and outer stationary solutions generates an asymptotic expansion of the particle concentration, which includes higher-order corrections to mean-field theory that depend on the positions of the clusters and the boundary of the domain. Motivated by a recent study of light-activated protein oligomerization in cells, we also develop the analogous theory for cluster formation in a three-dimensional (3D) domain. The details of the asymptotic analysis differ from the 2D case due to the contrasting singularity structure of 2D and 3D Green’s functions.&lt;/p&gt;&lt;p&gt;2D model of diffusion-based protein cluster formation in the presence of anchoring cites and particle recycling. &lt;b&gt;a&lt;/b&gt; A set of &lt;i&gt;N&lt;/i&gt; anchoring sites at positions &lt;span&gt;({textbf{x}}_j)&lt;/span&gt;, &lt;span&gt;(j=1,ldots ,N)&lt;/span&gt;, in a bounded domain &lt;span&gt;(Omega )&lt;/span&gt;. &lt;b&gt;b&lt;/b&gt; Diffusing particles accumulate at the anchoring sites resulting in the formation of particle aggregates or clusters &lt;span&gt;({{mathcal {U}}}_j)&lt;/span&gt;. &lt;b&gt;c&lt;/b&gt; The c","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11078859/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140890981","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":"Multifractal fluctuations in zebrafish (Danio rerio) polarization time series","authors":"Antonio R. de C. Romaguera,&nbsp;João V. A. Vasconcelos,&nbsp;Luis G. Negreiros-Neto,&nbsp;Nathan L. Pessoa,&nbsp;Jadson F. da Silva,&nbsp;Pabyton G. Cadena,&nbsp;Adauto J. F. de Souza,&nbsp;Viviane M. de Oliveira,&nbsp;Anderson L. R. Barbosa","doi":"10.1140/epje/s10189-024-00423-w","DOIUrl":"10.1140/epje/s10189-024-00423-w","url":null,"abstract":"<p>In this work, we study the polarization time series obtained from experimental observation of a group of zebrafish (<i>Danio rerio</i>) confined in a circular tank. The complex dynamics of the individual trajectory evolution lead to the appearance of multiple characteristic scales. Employing the Multifractal Detrended Fluctuation Analysis (MF-DFA), we found distinct behaviors according to the parameters used. The polarization time series are multifractal at low fish densities and their average scales with <span>(rho ^{-1/4})</span>. On the other hand, they tend to be monofractal, and their average scales with <span>(rho ^{-1/2})</span> for high fish densities. These two regimes overlap at critical density <span>(rho _c)</span>, suggesting the existence of a phase transition separating them. We also observed that for low densities, the polarization velocity shows a non-Gaussian behavior with heavy tails associated with long-range correlation and becomes Gaussian for high densities, presenting an uncorrelated regime.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140851833","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":"A multiple-timing analysis of temporal ratcheting","authors":"Aref Hashemi,&nbsp;Edward T. Gilman,&nbsp;Aditya S. Khair","doi":"10.1140/epje/s10189-024-00421-y","DOIUrl":"10.1140/epje/s10189-024-00421-y","url":null,"abstract":"<p>We develop a two-timing perturbation analysis to provide quantitative insights on the existence of temporal ratchets in an exemplary system of a particle moving in a tank of fluid in response to an external vibration of the tank. We consider two-mode vibrations with angular frequencies <span>(omega )</span> and <span>(alpha omega )</span>, where <span>(alpha )</span> is a rational number. If <span>(alpha )</span> is a ratio of odd and even integers (e.g., <span>(tfrac{2}{1},,tfrac{3}{2},,tfrac{4}{3})</span>), the system yields a net response: here, a nonzero time-average particle velocity. Our first-order perturbation solution predicts the existence of temporal ratchets for <span>(alpha =2)</span>. Furthermore, we demonstrate, for a reduced model, that the temporal ratcheting effect for <span>(alpha =tfrac{3}{2})</span> and <span>(tfrac{4}{3})</span> appears at the third-order perturbation solution. More importantly, we find closed-form formulas for the magnitude and direction of the induced net velocities for these <span>(alpha )</span> values. On a broader scale, our methodology offers a new mathematical approach to study the complicated nature of temporal ratchets in physical systems.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00421-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140810134","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 hard sphere model for single-file water transport across biological membranes","authors":"Gerald S. Manning","doi":"10.1140/epje/s10189-024-00419-6","DOIUrl":"10.1140/epje/s10189-024-00419-6","url":null,"abstract":"<p>We use Gürsey’s statistical mechanics of a one-dimensional fluid to find a formula for the <span>(P_textrm{f}/P_textrm{d})</span> ratio in the transport of hard spheres across a membrane through a narrow channel that can accommodate molecular movement only in single file. <span>(P_textrm{f})</span> is the membrane permeability for osmotic flow and <span>(P_textrm{d})</span> the permeability for exchange across the membrane in the absence of osmotic flow. The deviation of the ratio from unity indicates the degree of cooperative transport relative to ordinary diffusion of independent molecules. In contrast to an early idea that <span>(P_textrm{f}/P_textrm{d})</span> must be equal to the number of molecules in the channel, regardless of the physical nature of the interactions among the molecules, we find a functional dependence on the fractional occupancy of the length of the channel by the hard spheres. We also attempt a random walk calculation for <span>(P_textrm{d})</span> individually, which gives a result for <span>(P_textrm{f})</span> as well when combined with the ratio.</p><p>The convection/diffusion ratio for hard spheres in single-file transport</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00419-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603131","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":"Free surface oscillation driven by rotating stirrer","authors":"Tomoaki Watamura,&nbsp;Reiji Iwata,&nbsp;Kazuyasu Sugiyama","doi":"10.1140/epje/s10189-024-00420-z","DOIUrl":"10.1140/epje/s10189-024-00420-z","url":null,"abstract":"<p>To gain insights into the mechanisms of free surface oscillation in a rotating mixing container, we observe the free surface deformation and measure the torque acting on the bar. The container was half-filled with liquids. Periodic surface oscillation occurs. At the rotational speed where the amplitude of the oscillation reaches its maximum, the time-averaged torque also takes the local maximum values. To account for the sloshing mechanism, an equation of motion is derived using the Lagrangian mechanics; we found that the sloshing occurs when the collision frequency of bar on the surface is consistent with the natural frequency of the system and the damping coefficient is sufficiently smaller than unity. The time-averaged torque increases when the sloshing becomes violent. We conclude that the hydrodynamics of oscillation is successfully modeled using point-mass mechanics, and thus we can reasonably capture the rotation speed at which violent oscillation occurs.</p><p>Free surface deformation driven by the rotating arm in the cylindrical container which is half-filled with liquids</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00420-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140572028","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":"Modeling and correction of image drift in dynamic shadowgraphy experiments","authors":"Stefano Castellini,&nbsp;Matteo Brizioli,&nbsp;Cédric Giraudet,&nbsp;Marina Carpineti,&nbsp;Fabrizio Croccolo,&nbsp;Fabio Giavazzi,&nbsp;Alberto Vailati","doi":"10.1140/epje/s10189-024-00413-y","DOIUrl":"10.1140/epje/s10189-024-00413-y","url":null,"abstract":"<p>The study of phoretic transport phenomena under non-stationary conditions presents several challenges, mostly related to the stability of the experimental apparatus. This is particularly true when investigating with optical means the subtle temperature and concentration fluctuations that arise during diffusion processes, superimposed to the macroscopic state of the system. Under these conditions, the tenuous signal from fluctuations is easily altered by the presence of artifacts. Here, we address an experimental issue frequently reported in the investigation by means of dynamic shadowgraphy of the non-equilibrium fluctuations arising in liquid mixtures under non-stationary conditions, such as those arising after the imposition or removal of a thermal stress, where experiments show systematically the presence of a spurious contribution in the reconstructed structure function of the fluctuations, which depends quadratically from the time delay. We clarify the mechanisms responsible for this artifact, showing that it is caused by the imperfect alignment of the sample cell with respect to gravity, which couples the temporal evolution of the concentration profile within the sample with the optical signal collected by the shadowgraph diagnostics. We propose a data analysis protocol that enables disentangling the spurious contributions and the genuine dynamics of the fluctuations, which can be thus reliably reconstructed.</p><p>The imposition of a thermal gradient across a liquid mixture results in a time-dependent refractive index distribution. In the presence of a misalignment of the confining cell with respect to gravity, this leads to a deflection of the optical probe beam used to monitor concentration fluctuations within the sample in quantitative shadowgraphy experiments. If not properly accounted for, this effect can introduce a significant bias in the optical signal.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00413-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140572272","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}