The European Physical Journal E最新文献

{"title":"Conduction in heterogeneous systems in the low-frequency regime: variational principles and boundary integral equations","authors":"Francisco J. Solis,&nbsp;Vikram Jadhao","doi":"10.1140/epje/s10189-024-00449-0","DOIUrl":"10.1140/epje/s10189-024-00449-0","url":null,"abstract":"<p>The response of a homogeneous material to the presence of an external low-frequency oscillating electric field can be described by means of an effective complex conductivity. Low frequencies are characterized by negligible magnetic and radiative effects. The properties of heterogeneous systems, composed of multiple homogeneous regions, can be determined from those of the individual components and their geometric arrangement. Examples of such heterogeneous systems include soft materials such as colloidal suspensions, electrolyte systems, and biological tissues. The difference in the intrinsic conductivities between the homogeneous regions leads to the creation of an oscillating charge density localized at the interfaces between these regions. We show how to express key properties of these systems using this dynamic charge as a fundamental variable. We derive a boundary integral equation for the charges and reconstruct potentials and fields from its solution. We present a variational principle that recovers the fundamental equations for the system in terms of the oscillating charge and show that, in some formulations, the associated functional can be interpreted in terms of the power dissipated in the system. The boundary integral equations are numerically solved using a finite element method for a few illustrative cases.</p><p>Net field and accumulated surface charge in a two-region system. The two regions have contrasting complex conductivities. The system is in the presence of an oscillatory, uniform electric field</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338911","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":"Reinforcement learning of biomimetic navigation: a model problem for sperm chemotaxis","authors":"Omar Mohamed,&nbsp;Alan C. H. Tsang","doi":"10.1140/epje/s10189-024-00451-6","DOIUrl":"10.1140/epje/s10189-024-00451-6","url":null,"abstract":"<p>Motile biological cells can respond to local environmental cues and exhibit various navigation strategies to search for specific targets. These navigation strategies usually involve tuning of key biophysical parameters of the cells, such that the cells can modulate their trajectories to move in response to the detected signals. Here we introduce a reinforcement learning approach to modulate key biophysical parameters and realize navigation strategies reminiscent to those developed by biological cells. We present this approach using sperm chemotaxis toward an egg as a paradigm. By modulating the trajectory curvature of a sperm cell model, the navigation strategies informed by reinforcement learning are capable to resemble sperm chemotaxis observed in experiments. This approach provides an alternative method to capture biologically relevant navigation strategies, which may inform the necessary parameter modulations required for obtaining specific navigation strategies and guide the design of biomimetic micro-robotics.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11436411/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338912","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 Comprehensive study on the different types of soil desiccation cracks and their implications for soil identification using deep learning techniques","authors":"Emanual Daimari,&nbsp;Sai Ratna,&nbsp;P. V. S. S. R. Chandra Mouli,&nbsp;V. Madhurima","doi":"10.1140/epje/s10189-024-00453-4","DOIUrl":"10.1140/epje/s10189-024-00453-4","url":null,"abstract":"<div><p>Rapid drying of soil leads to its fracture. The cracks left behind by these fractures are best seen in soils such as clays that are fine in the texture and shrink on drying, but this can be seen in other soils too. Hence, different soils from the same region show different characteristic desiccation cracks and can thus be used to identify the soil type. In this paper, three types soils namely clay, silt, and sandy-clay-loam from the Brahmaputra river basin in India are studied for their crack patterns using both conventional studies of hierarchical crack patterns using Euler numbers and fractal dimensions, as well as by applying deep-learning techniques to the images. Fractal dimension analysis is found to be an useful pre-processing tool for deep learning image analysis. Feed forward neural networks with and without data augmentation and with the use of filters and noise suggest that data augmentation increases the robustness and improves the accuracy of the model. Even on the introduction of noise, to mimic a real-life situation, 92.09% accuracy in identification of soil was achieved, proving the combination of conventional studies of desiccation crack images with deep learning algorithms to be an effective tool for identification of real soil types.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338897","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":"Rotational dynamics of a disk in a thin film of weakly nematic fluid subject to linear friction","authors":"Abdallah Daddi-Moussa-Ider,&nbsp;Elsen Tjhung,&nbsp;Marc Pradas,&nbsp;Thomas Richter,&nbsp;Andreas M. Menzel","doi":"10.1140/epje/s10189-024-00452-5","DOIUrl":"10.1140/epje/s10189-024-00452-5","url":null,"abstract":"<div><p>Dynamics at low Reynolds numbers experiences recent revival in the fields of biophysics and active matter. While in bulk isotropic fluids it is exhaustively studied, this is less so in anisotropic fluids and in confined situations. Here, we combine the latter two by studying the rotation of a disk-like inclusion in a uniaxially anisotropic, globally oriented, incompressible two-dimensional fluid film. In terms of a perturbative expansion in parameters that quantify anisotropies in viscosity and in additional linear friction with a supporting substrate or other type of confinement, we derive analytical expressions for the resulting hydrodynamic flow and pressure fields as well as for the resistance and mobility coefficients of the rotating disk. It turns out that, in contrast to translational motion, the solutions remain well-behaved also in the absence of the additional linear friction. Comparison with results from finite-element simulations shows very good agreement with those from our analytical calculations. Besides applications to describe technological systems, for instance, in the area of microfluidics and thin cells of aligned nematic liquid crystals, our solutions are important for quantitative theoretical approaches to fluid membranes and thin films in general featuring a preferred direction.</p></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11424714/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142338913","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":"Surface conversion of the dynamics of bacteria escaping chemorepellents","authors":"Asma Braham,&nbsp;Laurence Lemelle,&nbsp;Romain Ducasse,&nbsp;Houyem Toukabri,&nbsp;Eleonore Mottin,&nbsp;Benoit Fabrèges,&nbsp;Vincent Calvez,&nbsp;Christophe Place","doi":"10.1140/epje/s10189-024-00450-7","DOIUrl":"10.1140/epje/s10189-024-00450-7","url":null,"abstract":"<p>Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile <i>E. coli</i> (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO₃)₂-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their <i>primo</i> approach to the surface (&lt; 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-024-00450-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142247386","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":"Insertion of anionic synthetic clay in lamellar surfactant phases","authors":"Isabelle Grillo,&nbsp;Sylvain Prévost,&nbsp;Thomas Zemb","doi":"10.1140/epje/s10189-024-00447-2","DOIUrl":"10.1140/epje/s10189-024-00447-2","url":null,"abstract":"<p>We describe the different mixed colloidal solutions that can be obtained when mixing equivalent quantities of a synthetic anionic clay to surfactants forming lamellar phases in the absence of added salt. The important quantity driving toward insertion or depletion is the osmotic pressure, of the lamellar phase and of the clay alone. Competition for water is the main driving force toward dispersion, inclusion or exclusion (phase separation). In the case of a nonionic surfactant (<span>(hbox {C}_{12}hbox {E}_{5})</span>) mixed with Laponite, undulations quenched by the surfactant-decorated clay lead to swelling; inclusion is not observed due to differences in rigidity. Long-range order is weakened leading eventually to the exclusion of surfactant in excess. In the case of a double anionic system (AOT-Laponite), electrostatic is dominant and the three regimes are encountered. In the catanionic case, admixing the double chain cationic lipid DDAB to the clay (in large charge excess), the platelets are coated by a positively charged bilayer. Long-range order is very efficiently dampened. From a low threshold (2% by weight), there is exclusion of a clay-poor collapsed lamellar phase, detected by the swelling of the main phase. The cationized clay does not interfere with the molecular force balance: the location of the critical point is unchanged. At high Laponite concentration, a very puzzling microstructure is observed. Some phase diagrams as well as representative SANS and SAXS data are extracted from the complete results concerning the lyotropic lamellar phase mixing problem available with all measures and evaluations of osmotic pressures in the PhD of the late Isabelle Grillo.</p><p>Binary surfactant–water systems often form lamellar phases with spacing and osmotic pressure imposed by molecular interactions, while clay forms sols, gels and flocs with smectic order. The question addressed here is: <i>“which mechanism is dominant in the center of the ternary phase diagram?”</i> </p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216469","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":"Antiferromagnetic liquid-crystal suspensions of goethite nanorods: three mechanisms of magnetic field influence on orientational structure","authors":"Danil A. Petrov,&nbsp;Ilya A. Chupeev","doi":"10.1140/epje/s10189-024-00448-1","DOIUrl":"10.1140/epje/s10189-024-00448-1","url":null,"abstract":"<p>The study looks into magnetically induced orientational transitions in suspensions of goethite nanorods based on a nematic liquid crystal. The study considers magnetically compensated suspension, which is a liquid-crystal analogue of an antiferromagnet. Unlike conventional magnetic particles, goethite nanorods have a remanent magnetic moment directed along the long axis of the particle and also they have negative diamagnetic anisotropy. Thus, it can be claimed that liquid-crystal composites of goethite nanorods have three mechanisms of interaction with an external magnetic field. The first two mechanisms are originally quadrupolar and are related to diamagnetic susceptibility anisotropies of liquid-crystal matrix and impurity goethite nanorods. The third mechanism is a dipolar one and is due to a remanent longitudinal magnetic moment of each dispersed particle. The magnetic-field-induced birefringence is used to show that the presence of three competing orientational mechanisms of interaction with an external magnetic field can both increase and decrease the Fréedericksz transition threshold compared to a pure liquid crystal. Diagrams of orientational phases of the suspension were constructed, and cases of various orientational mechanism predominance were analysed. Besides, a representation of the free energy of the suspension near the Fréedericksz transition in the form of the Landau expansion was obtained. This made it possible to establish that the Fréedericksz transition can occur as a phase transition of both the first and second order.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141970347","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":"On pressure-driven Poiseuille flow with non-monotonic rheology","authors":"L. Talon,&nbsp;D. Salin","doi":"10.1140/epje/s10189-024-00444-5","DOIUrl":"10.1140/epje/s10189-024-00444-5","url":null,"abstract":"&lt;p&gt;Shear thickening fluids are liquids that stiffen as the applied stress increases. If many of these types of fluids follow a monotonic rheological curve, some experimental and numerical studies suggest that certain fluids, like cornstarch, may exhibit a non-monotonic, S-shaped rheology. Such non-monotonic behavior has however proved very difficult to observe experimentally in classical rheometer. To explain such difficulties, the possible presence of vorticity banding in the rheometer has been considered. To prevent such instabilities, we use a capillary rheometer, which is a cylindrical tube, measuring the flow rate versus the applied pressure drop. With this setup, we indeed observe a non-monotonic behavior: the flow rate increases monotonically at low pressure drops up to a maximum, after which it abruptly decreases to an almost constant flow rate regardless of further increases in pressure drop. This maximum-jump–plateau behavior occurs over a wide range of concentrations and is reproducible without hysteresis, which is in agreement with an S-shaped rheology. However, the obtained flow versus pressure difference function &lt;span&gt;(Q(Delta P))&lt;/span&gt; does not agree with the classical Wyart–Cates rheological model, which predicts an S-shaped non-monotonic function, but with neither a jump nor a plateau. To understand this jump–plateau behavior, we remark that any rheological model would establish a relationship between the flow rate and the local pressure gradient, but not the total pressure drop. We thus discuss and analyze the implications of having an S-shaped non-monotonic flow rate-pressure gradient in Poiseuille flow. In particular, we discuss the possibility of a non-uniform pressure gradient in the direction of the flow, i.e., a kind of streamwise banding. The key issue is then the selection of the gradient pressure distribution along the tube. One solution could arise from an analogy of this problem with the spinodal decomposition. It, however, leads to an increase in flow rate with &lt;span&gt;(partial _xP)&lt;/span&gt; up to a plateau between two values of &lt;span&gt;(partial _xP)&lt;/span&gt; as determined by the Maxwell construction. To account for the bump–jump behavior, we have implemented a simple dynamical stochastic version of the Wyart–Cates model, where the thickening occurs with a characteristic time. As a result, with increasing the total pressure drop, the flow rate increases monotonically up to a maximum value. Beyond this point, the flow rate drops abruptly to a lower value, forming a slowly decreasing plateau. This behavior is likely to account for the maximum-jump–plateau observed in the experiments. We also show that in such a system, the final state is quite sensitive to the initial state of the fluid, especially its homogeneity. Our results then demonstrate that the mere presence of a non-monotonic rheological curve is sufficient to predict the occurrence of stress banding in the streamwise direction and a plateau flow rate, even if the s","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141888109","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":"Mathematical modeling for prediction of physicochemical characteristics of cardiovascular drugs via modified reverse degree topological indices","authors":"Micheal Arockiaraj,&nbsp;A. Berin Greeni,&nbsp;A. R. Abul Kalaam,&nbsp;Tariq Aziz,&nbsp;Metab Alharbi","doi":"10.1140/epje/s10189-024-00446-3","DOIUrl":"10.1140/epje/s10189-024-00446-3","url":null,"abstract":"<p>Global health concerns persist due to the multifaceted nature of heart diseases, which include lifestyle choices, genetic predispositions, and emerging post-COVID complications like myocarditis and pericarditis. This broadens the spectrum of cardiovascular ailments to encompass conditions such as coronary artery disease, heart failure, arrhythmias, and valvular disorders. Timely interventions, including lifestyle modifications and regular medications such as antiplatelets, beta-blockers, angiotensin-converting enzyme inhibitors, antiarrhythmics, and vasodilators, are pivotal in managing these conditions. In drug development, topological indices play a critical role, offering cost-effective computational and predictive tools. This study explores modified reverse degree topological indices, highlighting their adjustable parameters that actively shape the degree sequences of molecular drugs. This feature makes the approach suitable for datasets with unique physicochemical properties, distinguishing it from traditional methods that rely on fixed degree approaches. In our investigation, we examine a dataset of 30 drug compounds, including sotagliflozin, dapagliflozin, dobutamine, etc., which are used in the treatment of cardiovascular diseases. Through the structural analysis, we utilize modified reverse degree indices to develop quantitative structure–property relationship (QSPR) models, aiming to unveil essential understandings of their characteristics for drug development. Furthermore, we compare our QSPR models against the degree-based models, clearly demonstrating the superior effectiveness inherent in our proposed method.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141888108","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":"Effect of bottom bumpiness of vibrated closed container on granular dissipation behavior","authors":"Wenzhe Li,&nbsp;Kai Zhang,&nbsp;Fugui Sun,&nbsp;Meng Chen","doi":"10.1140/epje/s10189-024-00443-6","DOIUrl":"10.1140/epje/s10189-024-00443-6","url":null,"abstract":"<div><p>The dissipation behavior of granular balls inside quasi-two-dimensional closed containers with different levels of bottom bumpiness under vibration is examined in this article using the discrete element method. The quasi-two-dimensional closed granular system used in this paper has dimensions of <span>(L_{x} times L_{y} times L_{z} = 60,{text{mm}} times 5,{text{mm}} times 120,{text{mm}})</span>, and the diameters of the 279 filled granular balls are 4 mm. First, the dynamic behavior and damping effects of granular balls within a flat-bottomed closed container are explored across the range of relevant excitation parameters, identifying four high damping granular phases. Second, this study investigated the impact of the container's bottom surface bumpiness, convex height, and number of bumps on the dissipative behavior of internal granular balls. The findings reveal that a single 2 mm bump on the container's bottom surface maximally enhances the damping effect on the granular balls. Finally, by comparing the optimal damping behavior of granular balls inside a flat-bottomed container with that of a container featuring a single 2 mm bump at the bottom, this study revealed how the protruding bottom surface enhances the damping effect on the granular balls inside the container. This provides theoretical support for optimizing the performance of granular dampers in engineering practice by controlling the morphology of the cavity bottom surface.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"47 7","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141787033","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}