The synchronization and bundling process of bacterial flagella is investigated by mesoscale hydrodynamic simulations. Systems with two to six are considered, which anchored at one end, driven a constant torque. A flagellum modelled as linear helical structure composed mass points their elastic shape maintained bonds, bending, torsional potentials. characteristic times for analyzed in terms motor torque, separation, number flagella. We find that interactions determine the behavior. time...

CONSPECTUS: Diffusion is the principal transport mechanism that controls motion of solute molecules and other species in solution; however, random walk process underlies diffusion slow often nonspecific. Although an essential for biological realm, systems have devised more efficient mechanisms using molecular motors. Most motors utilize some form chemical energy derived from their surroundings to induce conformational changes order carry out specific functions. These small operate presence...

Peritrichous bacteria exploit bundles of helical flagella for propulsion and chemotaxis. Here, changes in the swimming direction (tumbling) are induced by a change rotational frequency some flagella. Employing coarse-grained modeling simulations, we investigate dynamical properties driven mismatched motor torques. Over broad range distances between anchors applied torque differences, find stable bundled state, which is important robust directional motion bacterium. With increasing...

Synthetic chemically-powered motors with various geometries have potentially new applications involving dynamics on very small scales.

Self-propelling chemical motors have thus far required the fabrication of Janus particles with an asymmetric catalyst distribution. Here, we demonstrate that simple, isotropic colloids can spontaneously assemble to yield dimer self-propel. In a mixture titanium dioxide photo-chemical catalytic activity and passive silica colloids, light illumination causes diffusiophoretic attractions between active leads formation dimers. The dimers constitute symmetry-broken motor, whose dynamics be fully...

The concentration dependence of the conformations ring polymers is investigated by lattice Monte Carlo simulations and compared with that linear polymers. relative radii gyration follow a universal master curve as function scaled for various chain lengths, scaling relationship ⟨Rg2⟩ ∼ ϕ–0.25, which consistent theory neutron scattering experiments. Ring different lengths also behavior broad crossover to ϕ–0.59 long chains. between chain-length radius implies N0.72, indicating highly collapsed...

In the presence of a chemically active particle, nearby inert particle can respond to concentration gradient and move by diffusiophoresis. The nature motion is studied for two cases: first, fixed reactive sphere moving sphere, second, freely spheres. continuum reaction-diffusion Stokes equations are solved analytically these systems microscopic simulations dynamics carried out. Although relative velocities spheres very similar in systems, local global structures streamlines flow velocity...

Active media, whose constituents are able to move autonomously, display novel features that differ from those of equilibrium systems. In addition naturally-occurring active systems such as populations swimming bacteria, synthetic self-propelled nanomotors have been developed. These interesting because their potential applications in a variety fields. Janus particles, motors spherical geometry with one hemisphere catalyzes the conversion fuel product and noncatalytic hemisphere, can propel...

A detailed analysis of the efficiency a Monte-Carlo (MC) method employing non-local moves for simple lattice ring polymers is presented. While introduction kink-translocation linear chains results in expected speedup by factor order number sites, this significantly reduced melt rings.

Inspired by recent experiments using synthetic microswimmers to manipulate droplets, we investigate the low-Reynolds-number locomotion of a model swimmer (a spherical squirmer) encapsulated inside droplet comparable size in another viscous fluid.

Some bacteria enter mucus layers protecting epithelial cells by chemically changing the rheological properties from a high-viscosity gel to low-viscosity solution in which it may self-propel. An analytical two-fluid model is presented for this process of swimming self-generated confinement.

The diffusion-influenced reversible reaction of a neutral particle and charged in an external field is analytically solved three dimensions. A generalized nonisotropic boundary condition used kinetic equation for the probability density function set up. tridiagonal matrix derived coefficients series solution we obtain within diagonal approximation Laplace domain. We also find that long time asymptotic behavior first term shows transition from power law to exponential as strength increased....

Janus particles with the ability to move phoretically in self-generated chemical concentration gradients are model systems for active matter. Their motion typically consists of straight paths rotational diffusion being dominant reorientation mechanism. In this paper, we show theoretically that by a suitable surface coverage both activity and mobility, translational can be induced arbitrarily three dimensions. The resulting trajectories general helical, their pitch radius controlled adjusting...

The dynamics of a spherical chemically-powered synthetic colloidal motor that operates by self-diffusiophoretic mechanism and has catalytic domain arbitrary shape is studied using both continuum theory particle-based simulations. executes active rotational motion when self-generated concentration gradients interactions between the chemical species surface break symmetry. Local variations reaction rates on with sizes shapes provide such broken symmetry conditions. A theoretical description...

The excited-state reversible reaction of a neutral particle and charged in an external electric field is studied three dimensions. This work extends the previous investigation for ground-state [S. Y. Reigh et al., J. Chem. Phys. 129, 234501 (2008)] to with two different lifetimes quenching. analytic series solutions all fundamental probability density functions are obtained help diagonal approximation. They found be excellent agreement exact numerical anisotropic diffusion-reaction...

E-mail: hkim@donga.ac.krReceived November 17, 2011, Accepted January 12, 2012The direct calculation method is generalized to the excited-state diffusion-influenced reversible reaction of aneutral and a charged particle under an external field with two different lifetimes quenching in threedimensions. The present provides alternative way calculate binding probability densityfunctions survival probabilities from corresponding irreversible results. solutions are obtainedas series by diagonal...

In the presence of an external electric field, ground-state \documentclass[12pt]{minimal}\begin{document}$A+B^q \rightleftharpoons C^q + D$\end{document}A+Bq⇌Cq+D diffusion-influenced reversible reaction for a geminate pair, neutral and charged particle, is investigated in three dimensions. The probability density functions, rates reactions, survival probabilities individual particles are analytically derived Laplace domain terms series solutions. long-time kinetics functions reactions...

In the presence of an external electric field, excited-state \documentclass[12pt]{minimal}\begin{document}$A+B^{*q} \rightleftharpoons C^{*q}+D$\end{document}A+B*q⇌C*q+D diffusion-influenced geminate reversible reaction a neutral particle and charged particle, with two unimolecular decay rates contact quenching processes, is investigated in three dimensions. The probability density functions to find individual particles, reactions, survival probabilities are analytically derived Laplace...

Kinetics of a geminate particle pair with no interparticle interactions controlled by diffusion-limited reversible reactions is investigated in the presence various possible external fields such as electric or gravitational based on continuum theory. Diffusion equations subject to multiple are analytically solved Green functions and physical quantities binding survival probabilities derived. Particularly, local at specific location reaction surface depending initial distance orientation...

The bacterium Helicobacter pylori causes ulcers in the stomach of humans by invading mucus layers protecting epithelial cells. It does so chemically changing rheological properties from a high-viscosity gel to low-viscosity solution which it may self-propel. We develop two-fluid model for this process swimming under self-generated confinement. solve exactly flow and locomotion speed spherical swimmer located spherically symmetric system two Newtonian fluids whose boundary moves with swimmer....

In the presence of a chemically active particle, nearby inert particle can respond to concentration gradient and move by diffusiophoresis. The nature motion is studied for two cases: first, fixed reactive sphere moving sphere, second, freely spheres. continuum reaction-diffusion Stokes equations are solved analytically these systems microscopic simulations dynamics carried out. Although relative velocities spheres very similar in systems, local global structures streamlines flow velocity...

The dynamics of a spherical chemically-powered synthetic colloidal motor that operates by self-diffusiophoretic mechanism and has catalytic domain arbitrary shape is studied using both continuum theory particle-based simulations. executes active rotational motion when self-generated concentration gradients interactions between the chemical species surface break symmetry. Local variations reaction rates on with sizes shapes provide such broken symmetry conditions. A theoretical description...