Unbiased diffusion through a linear porous media with periodic entropy barriers: A tube formed by contacting ellipses

This work is devoted to the study of unbiased diffusion of point-like brownian particles through channels with radial symmetry of varying cross-section and elliptic shape. the effective one-dimensional reduction is used with distinct forms of a position-dependent diffusion coefficient,d (x),found in literature,to obtain expressions for (i) narrow escape times from a single open-ended tube,(ii) its correspondent effective diffusion coefficient,both as functions of the eccentricity of the tube,ε,where ε = 0 returns the system to a spherical vesicle with two open opposite sides,and (iii) finally,lifson-jackson formula that is used to compute expressions to assess the mean effective diffusion coefficient for a periodic elliptic channel formed by contacting ellipses,also as a function of the eccentricity. mathematical expressions are presented and contrasted against computational simulations to validate them. © 2015 yoshua chavez et al.