We use Langevin dynamics simulations to study the mass diffusion problem across two adjacent porous layers of different transport properties. At the interface between the layers, we impose the Kedem-Katchalsky (KK) interfacial boundary condition that is well suited in a general situation. A detailed algorithm for the implementation of the KK interfacial condition in the Langevin dynamics framework is presented. As a case study, we consider a two-layer diffusion model of a drug-eluting stent. The simulation results are compared with those obtained from the solution of the corresponding continuum diffusion equation, and an excellent agreement is shown.
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http://dx.doi.org/10.1016/j.compbiomed.2020.103932 | DOI Listing |
Phys Rev Lett
December 2024
Institut Langevin, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France.
The interaction between waves and evolving media challenges traditional conservation laws. We experimentally investigate the behavior of elastic wave packets crossing a moving interface that separates two media with distinct propagation properties, observing the noninvariance of wavelength and frequency. Our experimental setup employs an elastic strip whose local stretching can be dynamically altered by pulling one end at a constant velocity.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
University of Maryland, College Park, Joint Quantum Institute, Condensed Matter Theory Center and, Department of Physics, Maryland 20742-4111, USA.
Discrete time crystals are novel phases of matter that break the discrete time translational symmetry of a periodically driven system. In this Letter, we propose a classical system of weakly nonlinear parametrically driven coupled oscillators as a test bed to understand these phases. Such a system of parametric oscillators can be used to model period-doubling instabilities of Josephson junction arrays as well as semiconductor lasers.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Soft Matter Biophysics, Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
Glycolipids are known to stabilize biomembrane multilayers through preferential sugar-sugar interactions that act as weak transient membrane cross-links. Here, we use small-angle and quasi-elastic neutron scattering on oligolamellar phospholipid vesicles containing defined glycolipid fractions in order to elucidate the influence of glycolipids on membrane mechanics and dynamics. Small-angle neutron scattering (SANS) reveals that the oligolamellar vesicles (OLVs) obtained by extrusion are polydisperse with regard to the number of lamellae, , which renders the interpretation of the quasi-elastic neutron spin echo (NSE) data nontrivial.
View Article and Find Full Text PDFSoft Matter
January 2025
College of Chemistry, Sichuan University, Chengdu 610064, China.
Biomolecules usually adopt ubiquitous circular structures which are important for their functionality. Based on three-dimensional Langevin dynamics simulations, we investigate the conformational change of a polymer confined in a spherical cavity. Both passive and active polymers with either homogeneous or heterogeneous stiffness are analyzed in a comparative manner.
View Article and Find Full Text PDFBayesian Anal
June 2024
Department of Statistics, Purdue University, West Lafayette, IN 47907, USA.
The exponential random graph model (ERGM) is a popular model for social networks, which is known to have an intractable likelihood function. Sampling from the posterior for such a model is a long-standing problem in statistical research. We analyze the performance of the stochastic gradient Langevin dynamics (SGLD) algorithm (also known as noisy Longevin Monte Carlo) in tackling this problem, where the stochastic gradient is calculated via running a short Markov chain (the so-called inner Markov chain in this paper) at each iteration.
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