Sloppy gear mechanism for coupled stochastic transportation: From antiequilibrium flow to kinetic selectivity

Abstract

Nonequilibrium transportation of particles through a restricted space (such as porous media or narrow channels) significantly differs from free space. With a simple model of two types of particles competing to transport via a passive single-lane channel connecting two chemical baths, we find two dynamical modes of transportation—the dud mode and the ratchet mode. At the ratchet mode, the gradient flow of one type of particle forces the other into a transient antiequilibrium flow against its gradient. At the dud mode, the two types of particles both flow according to their gradients. This counterintuitive nonequilibrium effect can be explained by a sloppy gear mechanism. In addition to the antigradient flow observed in the ratchet mode, we find that the nonequilibrium sloppy gear mechanism suppresses the flow of one particle while allowing the flow for the other. This mechanism provides a general theoretical framework to explain and design the selective transportation of particles via passive channels.

Sloppy gear mechanism for coupled stochastic transportation: From antiequilibrium flow to kinetic selectivity. Chase Slowey, Zhiyue Lu. Phys. Rev. Research. 2022, 6, 21. DOI: 10.1103/PhysRevResearch.4.023234