Soft Matter最新文献

{"title":"Medium-assisted tumbling controls bacteria exploration in a complex fluid.","authors":"Héctor Urra, Thierry Darnige, Xavier Benoit-Gonin, Justine Laurent, Angela Dawson, Wilson C K Poon, Eric Clément","doi":"10.1039/d5sm00452g","DOIUrl":"https://doi.org/10.1039/d5sm00452g","url":null,"abstract":"<p><p>In nature, many fluids that harbor bacterial populations or protect against microbial contamination exhibit non-Newtonian rheology. To study, in such complex environments, the spatial exploration of <i>E. coli</i> bacteria, a model multi-flagellated microorganism, we design a motility medium with tunable macroscopic rheology. By increasing the solid charge in soft carbomer grains, we transition from a Newtonian viscous suspension to a yield-stress fluid. Using a 3D Lagrangian tracking device, we collected many individual bacterial tracks and characterized changes in motility properties such as swimming speed, persistence times and diffusivity for both a wild-type and a smooth runner mutant, up to the formation of a motility barrier at higher carbomer concentrations. We show that the presence of local mechanical disorder and resistance to penetration essentially override the biologically driven run-and-tumble navigation process. This \"medium-assisted\" exploration scenario is characterized by directional switching and stop-and-go kinematics and is closely related to the flexibility of the flagellar bundle.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144688415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The size ratio effect on the microstructure and magnetization of a bidisperse magnetic colloidal suspension.","authors":"Luis R Pérez-Marcos, Ronal A DeLaCruz-Araujo, Heberth Diestra-Cruz, Obidio Rubio, Ubaldo M Córdova-Figueroa, Glenn C Vidal-Urquiza","doi":"10.1039/d5sm00180c","DOIUrl":"https://doi.org/10.1039/d5sm00180c","url":null,"abstract":"<p><p>This research examines how the size ratio influences the microstructure and time-dependent magnetization in a bidisperse magnetic colloidal suspension under a uniform magnetic field. Two types of particles model the bidisperse suspension: the small particles of radius <i>R</i>_s and the large particles of radius <i>R</i>_l. The size ratio, <i>ξ</i> = <i>R</i>_l/<i>R</i>_s, defines the particle size difference. The total volume fraction of the suspension, <i>ϕ</i>, is obtained from <i>ϕ</i> = <i>ϕ</i>_s + <i>ϕ</i>_l, where <i>ϕ</i>_s and <i>ϕ</i>_l are the volume fractions of the small and large particles, respectively. The magnetic dipole-dipole interaction among the small particles and the large ones is characterized by the dipolar coupling parameters <i>λ</i>_s and <i>λ</i>_l, respectively. The interactions among the applied magnetic field and the magnetic dipoles of the small and large particles are measured by the Langevin parameters <i>α</i>_s and <i>α</i>_l, respectively. This study performs Brownian dynamics (BD) simulations of a bidisperse suspension comprising <i>N</i> = 1000 particles, with <i>ϕ</i> = 10^-3 and <i>ϕ</i>_s = <i>ϕ</i>_l = 5 × 10^-4. Also, <i>α</i>_s ranges from 0 to 1000, and <i>λ</i>_s from 5 to 30. The size ratio, <i>ξ</i>, takes values of 1, 2 and 3. The values of <i>λ</i>_l and <i>α</i>_l are computed by the parameters aforementioned by assuming that all particles exhibit the same saturation magnetization. Our results show a rich variability in the microstructure as <i>ξ</i> increases. As the large particles increase in size, they exhibit a greater magnetic dipole moment, which induces a non-uniform local magnetic field around them. The surrounding small particles then aggregate with the large ones, driven by this local magnetic field. Small <i>α</i>_s values lead to the formation of flux-closure structures such as rings of small and large particles as well as shell-like structures, which consist of small particles surrounding the large ones. The formation of these microstructures directly affects time-dependent magnetization of the suspension, which exhibits a decay with time in the limit of long times. These findings have important implications for synthesizing magnetic colloidal suspensions with enhanced properties.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144688417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Collision of surfactant-laden droplets: insights from molecular dynamics simulation.","authors":"Soheil Arbabi, Piotr Deuar, Rachid Bennacer, Zhizhao Che, Panagiotis E Theodorakis","doi":"10.1039/d5sm00589b","DOIUrl":"https://doi.org/10.1039/d5sm00589b","url":null,"abstract":"<p><p>We study the collision dynamics of surfactant-laden droplets and compare it with that of pure water droplets, with a focus on the bridge growth rate, energy balance, and disk dynamics, distinguishing the cases of head-on and off-centre collisions. By using molecular dynamics simulation of a coarse-grained model, it is found that initial linear scaling describes the first stage of the collision process, which is followed by power-law dynamics, in contrast to an initial thermal regime and a subsequent power-law behaviour observed for droplet coalescence. The transition between the two regimes occurs faster for surfactant-laden droplets. At higher collision velocities, the linear regime dominates the process with a gradual reduction of the power-law behaviour, reaching a situation in which the bridge growth is fully characterised by linear dynamics. The different behaviour of the droplets is presented in the form of a diagram of different scenarios, namely coalescence, separation, and splattering. In particular, it is found that higher velocities and larger offsets increase the likelihood of separation and splattering, with water droplets producing a greater number of satellite droplets due to reduced viscous damping. Also, a disk-like structure is observed as a result of collision, but it is less pronounced in the case of surfactant-laden droplets, due to higher dissipation of energy.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144688413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating polymer infiltration kinetics in nanoporous metal scaffolds using UV-vis spectroscopy.","authors":"Weiwei Kong, Chuyi Pan, Rongyue Lin, Mengjie Fan, John M Vohs, Russell J Composto","doi":"10.1039/d5sm00423c","DOIUrl":"https://doi.org/10.1039/d5sm00423c","url":null,"abstract":"<p><p>This work demonstrates that the optical response of nanoporous gold (NPG) is directly related to the infiltration extent (IE) of the polymer. Infiltration of poly(2-vinylpyridine) (P2VP) into NPG with a pore radius (<i>R</i>_p) of 34 nm was investigated at 140 °C. The UV-vis spectra of the NPG display plasmon absorption peaks due to the Au ligaments that depend on the height of the P2VP infiltration front in the NPG film. During infiltration, the absorption peak position shifts to longer wavelengths, while the peak height, width, and area increase monotonically with time. For P2VP with molecular weights (<i>M</i>_w) from 85 kDa to 940 kDa, the time to reach 80% of the IE (<i>τ</i>_80%) scales as <i>M</i>1.35w, in good agreement with <i>in situ</i> spectroscopic ellipsometer results. AFM and XPS support the strong attraction of P2VP for the Au surface and pores as demonstrated by wetting of P2VP over surface ligaments and a shift of the 4f orbital from the N on P2VP to higher binding energy, respectively. Using nanorods configured as a \"T\" to model ligament geometry, discrete dipole approximation (DDA) simulations capture the optical properties of the P2VP/NPG nanocomposite during infiltration and confirm experimental results. The evolution of the P2VP/NPG optical properties is attributed mainly to an increase in the effective refractive index within the pores. This study presents UV-vis spectroscopy as an alternative method for studying polymer infiltration into nanoporous metal scaffold films.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144688414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-layered laminate architectures enhance the electromechanical response of PVDF-TrFE films.","authors":"Anna Šutka, Artis Linarts, Maksims Jurinovs, Krišjānis Šmits, Sergejs Gaidukovs, Peter C Sherrell, Andris Šutka","doi":"10.1039/d5sm00631g","DOIUrl":"https://doi.org/10.1039/d5sm00631g","url":null,"abstract":"<p><p>The digitisation of society and the rise of autonomous sensing networks have led to the need for independent and autonomous low-grade power supplies. Electromechanical harvesters, which convert motion or vibrations into electricity, show great promise for powering microelectronic devices. In particular, poly(vinylidene difluoride (PVDF) is an exemplar polymer material for electromechanical conversion and is highly attractive as a power source due to its exceptional chemical stability. In this study, we present an approach to enhance the electromechanical conversion of a PVDF co-polmyer by electrospinning multi-layered nanofiber laminate architectures, consisting of alternating smaller and larger diameter fibers. This alternative layer structure results in the introduction of oriented triboelectric dipoles within the volume of the laminate architecture, able to couple with the piezoelectric dipole of PVDF. The laminate shows an 11× improvement in electromechanical conversion when compared to an equivalent single diameter fiber network under identical conditions. The application of the laminate architecture to airflow and sound energy harvesting is also demonstrated, with a doubling of the peak-to-peak short-circuit current compared to a state-of-the-art commercial poled PVDF film. This approach provides a pathway to improve the electromechanical performance of PVDF for a wide array of electromechanical conversion applications.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144688416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase field model for viscous inclusions in anisotropic networks.","authors":"Aakanksha Gubbala, Anika M Jena, Daniel P Arnold, Sho C Takatori","doi":"10.1039/d5sm00478k","DOIUrl":"https://doi.org/10.1039/d5sm00478k","url":null,"abstract":"<p><p>The growth of viscous two-dimensional lipid domains in contact with a viscoelastic actin network was recently shown to exhibit unusual lipid domain ripening due to the geometry and anisotropy of the actin network [Arnold & Takatori. <i>Langmuir</i>. <b>40</b>, 26570-26578 (2024)]. In this work, we interpret previous experimental results on lipid membrane-actin composites with a theoretical model that combines the Cahn-Hilliard and Landau-de Gennes liquid crystal theory. In our model, we incorporate fiber-like characteristics of actin filaments and bundles through a nematic order parameter, and elastic anisotropy through cubic nematic gradients. Numerical simulations qualitatively agree with experimental observations, by reproducing the competition between the thermodynamic forces that coarsen lipid domains <i>versus</i> the elastic forces generated by the surrounding actin network that resist domain coarsening. We observe a decrease in the growth of domain sizes, finding <i>R</i>(<i>t</i>) ∼ <i>t</i>^<i>α</i> with <i>α</i> < 1/4 for different actin network stiffnesses, in sharp contrast to the ∼<i>t</i>^1/3 scaling for diffusive growth of domains in the absence of the actin network. Our findings may serve as a foundation for future developments in modeling elastic ripening in complex systems.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144681709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxygen deficiency drives drastic pattern transition in algal bioconvection.","authors":"Sangram Gore, Iraj Gholami, Samar O Ahmed, Tomiris Doskhozhina, Sai V R Ambadipudi, Albert J Bae, Azam Gholami","doi":"10.1039/d5sm00451a","DOIUrl":"https://doi.org/10.1039/d5sm00451a","url":null,"abstract":"<p><p>Suspensions of motile microorganisms can spontaneously form large-scale fluid motion, known as bio- convection, characterized by dense downwelling plumes separated by broad upwelling regions. In this study, we investigate bioconvection in shallow suspensions of <i>Chlamydomonas reinhardtii</i> confined within spiral-shaped boundaries, combining detailed experiments with three-dimensional simulations. Under open liquid-air interfaces, cells accumulate near the surface <i>via</i> negative gravitaxis, generating spiral-shaped density patterns that subsequently fragment into lattice-like clusters, leading to plume formation. Space-time analyses demonstrate coherent rotational dynamics, with predominantly inward-directed motion near the spiral core and bidirectional motion further out. Introducing confinement by sealing the upper boundary with an air-impermeable wall triggers dramatic pattern transitions due to oxygen depletion: initially stable arrangements reorganize into new structures with significantly reduced wavelengths. Complementary numerical simulations, based on incompressible Navier-Stokes equations incorporating negative buoyancy and active swimmer stress, successfully replicate initial pattern formation, subsequent instability, fragmentation into plumes, and emergence of strong vortical flows-nearly an order of magnitude faster than individual cell swimming. However, these models do not capture oxygen depletion-driven transitions observed experimentally. Our results highlight that geometric confinement, oxygen availability, and metabolic transitions critically regulate bioconvection dynamics, offering novel strategies for controlling microbial self-organization and fluid transport.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144681708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dispersions of weakly charged thermoresponsive microgels at high densities.","authors":"M Hildebrandt, D Pham Thuy, A Domgans, A Scotti, S Prévost, M Adhikari, J Horbach, M Karg","doi":"10.1039/d5sm00464k","DOIUrl":"https://doi.org/10.1039/d5sm00464k","url":null,"abstract":"<p><p>Poly-<i>N</i>-isopropylacrylamide-based microgels in aqueous dispersion exhibit a pronounced thermoresponse that allows to control their size and thus the volume fraction <i>via</i> temperature. Here, we study the phase behavior of aqueous dispersions of weakly charged microgels with small silica cores, employing different scattering techniques. From temperature- and concentration-dependent experiments in presence and absence of monovalent salt, we deduce phase diagrams. The central quantity to analyse the structure and thus the phase of the system is the static structure factor measured <i>via</i> small-angle scattering. As a reference, we also perform molecular dynamics computer simulations of systems of weakly charged particles, using a screened Coulomb (Yukawa) potential with a soft core to model the interactions between the microgels. For this model potential the phase diagram is known. By comparing structure factors determined by both experiment and simulation, we can assign the observed states of our soft model colloids to states in the Yukawa phase diagram.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144673379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Outstanding Reviewers for <i>Soft Matter</i> in 2024.","authors":"","doi":"10.1039/d5sm90125a","DOIUrl":"https://doi.org/10.1039/d5sm90125a","url":null,"abstract":"<p><p>We would like to take this opportunity to thank all of <i>Soft Matter</i>'s reviewers for helping to preserve quality and integrity in chemical science literature. We would also like to highlight the Outstanding Reviewers for <i>Soft Matter</i> in 2024.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144673382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Establishing physiologically relevant conditions for measuring the interfacial rheology of lung surfactants.","authors":"Yun-Han Huang, John M Frostad","doi":"10.1039/d5sm00323g","DOIUrl":"https://doi.org/10.1039/d5sm00323g","url":null,"abstract":"<p><p>Lung surfactants are essential in the human respiratory system due to their role in lowering surface tension and preventing alveoli from collapsing. The main component that serves this purpose is dipalmitoylphosphatidylcholine (DPPC), a type of phospholipid that is insoluble in water. In this work, we modified an interfacial dilational rheometer (IDR) to measure the dilational modulus of DPPC at physiologically relevant temperatures and employed it at frequencies close to those relevant to breathing. Our analysis reveals that in the liquid-expanded phase, the dilational modulus is governed solely by surface pressure and is independent of temperature. This key insight is supported by the close agreement between our interfacial dilational rheometer measurements and data from other techniques. We demonstrate that the method of interface formation, compression <i>versus</i> direct deposition, significantly impacts the measured interfacial rheology of DPPC, underscoring the importance of deformation history in replicating physiologically relevant lung conditions. Additionally, we demonstrate the need for further work to develop improved equations of state describing DPPC behavior in the liquid-expanded phase.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144673380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}