A5028221319- Material Dynamics and Properties
- Micro and Nano Robotics
- Advanced Thermodynamics and Statistical Mechanics
- Pickering emulsions and particle stabilization
- Electrostatics and Colloid Interactions
- Theoretical and Computational Physics
- Microfluidic and Bio-sensing Technologies
- Phase Equilibria and Thermodynamics
- Molecular Communication and Nanonetworks
- Spectroscopy and Quantum Chemical Studies
- Liquid Crystal Research Advancements
- Surfactants and Colloidal Systems
- Modular Robots and Swarm Intelligence
- Characterization and Applications of Magnetic Nanoparticles
- nanoparticles nucleation surface interactions
- Particle Dynamics in Fluid Flows
- Diffusion and Search Dynamics
- Nonlinear Dynamics and Pattern Formation
- Cold Atom Physics and Bose-Einstein Condensates
- Solidification and crystal growth phenomena
- Dust and Plasma Wave Phenomena
- Thermodynamic properties of mixtures
- Nanopore and Nanochannel Transport Studies
- Advanced Materials and Mechanics
- Vibration Control and Rheological Fluids
Heinrich Heine University Düsseldorf
2016-2025
Otto-von-Guericke University Magdeburg
2021
Instituto de Física Teórica
2015-2021
University of Warsaw
2020
Institut für Psychologische Psychotherapie
2020
Max Planck University of Twente Center for Complex Fluid Dynamics
2019
University of Gothenburg
2019
ESPCI Paris
2019
Gulliver
2019
University of Münster
2017
Differently from passive Brownian particles, active also known as self-propelled particles or microswimmers and nanoswimmers, are capable of taking up energy their environment converting it into directed motion. Because this constant flow energy, behavior can only be explained understood within the framework nonequilibrium physics. In biological realm, many cells perform motion, for example, a way to browse nutrients avoid toxins. Inspired by these motile microorganisms, researchers have...
We study experimentally and numerically a (quasi) two dimensional colloidal suspension of self-propelled spherical particles. The particles are carbon-coated Janus particles, which propelled due to diffusiophoresis in near-critical water-lutidine mixture. At low densities, we find that the driving stabilizes small clusters. higher undergoes phase separation into large clusters dilute gas phase. same qualitative behavior is observed simulations minimal model for repulsive lacking any...
Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior among the simplest forms life important for fluid mixing molecular transport on microscale. The mathematical characterization turbulence phenomena active nonequilibrium fluids proves even more difficult than conventional liquids or gases. It not known which features phases living...
Combining statistical-mechanical theories and neutron-scattering techniques, we show that the effective pair potential between star polymers is exponentially decaying for large distances crosses over, at a density-dependent corona diameter, to an ultrasoft logarithmic repulsion small distances. We also make theoretical prediction in concentrated polymer solutions, this interaction induces anomalous fluid structure factor which exhibits unusually pronounced second peak.
This review summarizes and assesses recent theoretical experimental advances, with special emphasis on the effective interaction between charge-stabilized colloids, in bulk or confined geometries, ambiguities of defining an charge colloidal particles. Some consideration is given to often neglected discrete solvent effects.
Abstract Activity and autonomous motion are fundamental in living engineering systems. This has stimulated the new field of ‘active matter’ recent years, which focuses on physical aspects propulsion mechanisms, motility-induced emergent collective behavior a larger number identical agents. The scale agents ranges from nanomotors microswimmers, to cells, fish, birds, people. Inspired by biological various designs synthetic nano- micromachines have been proposed. Such machines provide basis...
Micron-sized self-propelled (active) particles can be considered as model systems for characterizing more complex biological organisms like swimming bacteria or motile cells. We produce asymmetric microswimmers by soft lithography and study their circular motion on a substrate near channel boundaries. Our experimental observations are in full agreement with theory of Brownian dynamics particles, which couples translational orientational motion.
A geometrically based fundamental-measure free-energy density functional unified the scaled-particle and Percus-Yevick theories for hard-sphere fluid mixture. It has been successfully applied to description of simple (``atomic'') three-dimensional (3D) fluids in bulk slitlike pores, extended molecular fluids. However, this was unsuitable narrow cylindrical inadequate describing solid. In work we analyze reason these deficiencies, show that, fact, theory provides a 3D hard spheres with...
Overdamped Brownian motion of a self-propelled particle is studied by solving the Langevin equation analytically. On top translational and rotational diffusion, in context presented model, 'active' driven along its internal orientation axis. We calculate first four moments probability distribution function for displacements as time spherical with isotropic well an anisotropic ellipsoidal particle. In both cases either unconfined or confined to one two dimensions. A significant non-Gaussian...
The kinetic separation of repulsive active Brownian particles into a dense and dilute phase is analyzed using systematic coarse-graining strategy. We derive an effective Cahn-Hilliard equation on large length time scales, which implies that the process can be mapped onto passive particles. A lower density threshold for clustering found, our approach we demonstrate first proceeds via hysteretic nucleation scenario above higher changes spinodal-like instability. Our results are in agreement...
Abstract Many microorganisms, with phytoplankton and zooplankton as prominent examples, display phototactic behaviour, that is, the ability to perform directed motion within a light gradient. Here we experimentally demonstrate sensing of gradients can also be achieved in system synthetic photo-activated microparticles being exposed an inhomogeneous laser field. We observe strong orientational response particles because diffusiophoretic torques, which combination intensity-dependent particle...
Using Brownian dynamics computer simulations, we show that a two-dimensional suspension of self-propelled (''active'') colloidal particles crystallizes at sufficiently high densities. Compared to the equilibrium freezing passive particles, density is both significantly shifted and depends on structural or dynamical criterion employed. In nonequilibrium transition accompanied by pronounced heterogeneities. This leads region between liquid solid in which globally ordered but unordered...
Active particles that are self-propelled by converting energy into mechanical motion represent an expanding research realm in physics and chemistry. For micrometer-sized moving a liquid (“microswimmers”), most of the basic features have been described using model overdamped active Brownian motion. However, for macroscopic or microparticles gas, inertial effects become relevant such dynamics is underdamped. Therefore, recently, with inertia extending to Langevin include inertia. In this...
A basic statistical mechanics analysis of many-body systems with non-reciprocal pair interactions is presented. Different non-reciprocity classes in two- and three-dimensional binary (relevant to real experimental situations) are investigated, where the action-reaction symmetry broken for interaction between different species. The asymmetry characterized by a parameter $\Delta$, which ratio reciprocal forces. It shown that "constant" (when $\Delta$ independent interparticle distance $r$) one...
Abstract In an equilibrium thermal environment, random elastic collisions between background particles and a tracer establish the picture of Brownian motion fulfilling celebrated Einstein relation diffusivity mobility. However, extensions to link dissipation, fluctuations, nonequilibrium dynamical mechanisms in active matter systems are still debated. Here, we investigate experimentally impact on passive using vibrationally excited particles, that result multiple correlated tapping with...
The phase diagram of star polymer solutions in a good solvent is obtained over wide range densities and arm numbers by Monte Carlo simulations. effective interaction between the stars modeled an ultrasoft pair potential which logarithmic core-core distance. Among stable phases are fluid as well body-centered cubic, face-centered orthogonal, diamond crystals. In limited numbers, reentrant melting freezing transitions occur for increasing density.
We examine in full generality the phase behavior of systems whose constituent particles interact by means potentials that do not diverge at origin, are free attractive parts, and decay fast enough to zero as interparticle separation r goes infinity. By employing a mean field-density functional theory which is shown become exact high temperatures and/or densities, we establish criterion determines whether given system will freeze all or it display reentrant melting an upper freezing temperature.
Self-propelled particles move along circles rather than a straight line when their driving force does not coincide with propagation direction. Examples include confined bacteria and spermatozoa, catalytically driven nanorods, active, anisotropic colloidal vibrated granulates. Using non-Hamiltonian rate theory computer simulations, we study the motion of Brownian ``circle swimmer'' in confining channel. A sliding mode close to wall leads huge acceleration as compared bulk motion, which can...
A hard sphere system confined between two parallel plates is investigated theoretically. Using extensive Monte Carlo computer simulations, the phase diagram calculated for whole range of densities and plate separations ranging from one to particle diameters. There occurs a strong first-order fluid freezing transition both very weak discontinuous transitions different crystal structures, namely, layered, buckled, rhombic crystals. The results are compared with predictions free volume theory,...
The general possibility to align biological macromolecules in the magnetic field by presence of orienting agents such as lipid bicelles has led a wealth new structural parameters which can be derived from residual tensorial interactions high resolution NMR. Here, we report that alignment water soluble biomacromolecules achieved naturally occurring two-dimensional crystals (purple membrane) membrane protein bacteriorhodopsin. extent is tunable concentration purple membranes and addition salt...