The dielectric boundary force (DBF) is the force that induced charges at dielectric boundaries exert on the charge that induced them. The DBF is present in any electrostatic problem with a non-uniform dielectric constant, and is important in the case of charged particles near dielectric boundaries. Yet, it is absent in common continuum theories of charge distribution and of charge transport, su...

[Purpose] The purpose of this study was to investigate the effect of isometric hip adduction and abduction on trunk muscle activity during plank exercises. [Subjects and Methods] Nineteen healthy male subjects were recruited for this study. All subjects performed the traditional plank exercise (TP), plank exercise with isometric hip adduction (PHAD), and plank exercise with isometric hip abduct...

In this work, we are interested in effects of a simple profile of permanent charges on ionic flows. We determine when a permanent charge produces current reversal. We adopt the classical Poisson-NernstPlanck models of ionic flows for this study. The starting point of our analysis is the recently developed geometric singular perturbation approach for Poisson-Nernst-Planck models. Under the setti...

This article describes a numerical solution of the steady-state Poisson-Boltzmann-Smoluchowski (PBS) and Poisson-Nernst-Planck (PNP) equations to study diffusion in biomolecular systems. Specifically, finite element methods have been developed to calculate electrostatic interactions and ligand binding rate constants for large biomolecules. The resulting software has been validated and applied t...

The reduced 1D Poisson-Nernst-Planck (PNP) model of artificial nanopores in the presence of a permanent charge on the channel wall is studied. More specifically, we consider the limit where the channel length exceed much the Debye screening length and channel’s charge is sufficiently small. Ion transport is described by the nonequillibrium steady-state solution of the PNP system within a singul...

We simulate sodium chloride currents through the gramicidin A channel using the spectral element method to solve the three-dimensional Poisson–Nernst– Planck (PNP) equations. Using the spectral element method, we are able to simulate the entire channel, plus large enough portions of the lipid bilayer and baths to ensure that all boundary conditions are realistic. In these simulations, we rely o...

We present a comprehensive analysis of salt transport and overlimiting currents in a microchannel during concentration polarization. We have carried out full numerical simulations of the coupled Poisson-Nernst-Planck-Stokes problem governing the transport and rationalized the behavior of the system. A remarkable outcome of the investigations is the discovery of strong couplings between bulk adv...

Ionic channels play an important role in regulating the cell’s membrane potential and internal charge. This paper will focus on a continuum model of the KcsA potassium channel. We will derive the Poisson-Nernst-Planck (PNP) equations in general and then provide computational solutions for a 1D KcsA channel using experimentally determined parameters. The solution to the PNP equations consists of...

We are concerned with a model of ionic polymer-metal composite (IPMC) materials that consists of a coupled system of the Poisson and Nernst-Planck equations, discretized by means of the finite element method (FEM). We show that due to the transient character of the problem it is efficient to use adaptive algorithms that are capable of changing the mesh dynamically in time. We also show that due...