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arXiv 1509.02456math.AP
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具有空间效应的Poisson-Nernst-Planck方程的定态解

Stationary solutions to the Poisson-Nernst-Planck equations with steric effects

Li-Chang Hung, Mach Nguyet Minh

摘要:

离子转运,即离子穿过细胞膜的运动,在各种生物过程中起着至关重要的作用,并且可以通过具有空间效应的Poisson-Nernst-Planck方程(PNP-空间方程)来描述。本文证明了在齐次Neumann边界条件下,定态PNP空间方程等价于微分代数方程(DAE)系统。分析这个系统的DAE启发我们提出一个假设的耦合常数,所谓的\textbf{(H1)}将被引入\cref{Sec:model},这样,如果\textbf{(H1)}成立,稳态PNP立体方程承认一个唯一的固定$C^2$解决方案。此外,我们将指出当\textbf{(H1)}被破坏时会发生分叉,这可能与离子通道的打开和关闭有关。当\textbf{(H1)}失效时,我们还提出了一个简单的判据来检验DAE方程组是否存在唯一的单调$C^2$解,或唯一的单调分段$C^2$解,或三重分段$C^2$解.据作者所知,这是第一次利用这种DAE方法来获得两个相反电荷离子物种的稳态PNP空间方程的完整研究

英文摘要:

Ion transport, the movement of ions across a cellular membrane, plays a crucial role in a wide variety of biological processes and can be described by the Poisson-Nernst-Planck equations with steric effects (PNP-steric equations). In this paper, we shall show that under homogeneous Neumann boundary conditions, the steady-state PNP-steric equations are equivalent to a system of differential algebraic equations (DAEs). Analyzing this system of DAEs inspires us to propose an assumption on coupling constants, the so-called \textbf{(H1)} which will be introduced in \cref{Sec:model}, such that if \textbf{(H1)} holds true, the steady-state PNP-steric equations admit a unique stationary $C^2$ solution. Moreover, we shall point out the occurrence of bifurcation when \textbf{(H1)} is violated, which may relate to the opening and closing of the ion channels. When \textbf{(H1)} fails, we also suggest a simple criterion to check whether the system of DAE equations admits unique monotone $C^2$ solutions; or unique monotone piecewise $C^2$ solutions with vertical tangents; or triple piecewise $C^2$ solutions. To the best of the authors' knowledge, this is the first time such DAE approach has been utilized to obtain a complete investigation for the steady-state PNP-steric equations of two counter-charged ion species

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