在目前的工作中,我们研究的电解质溶液之间的平面表面与nonopatterned带电域,已连接到一个散装离子水库。该系统是通过改进的蒙特卡罗(MC)模拟方法,适用于模拟的电解质调制的表面电荷分布的存在下进行调查。我们还采用了线性方法的精神,经典的德拜-休克尔近似,它允许一个获得明确的表达式的平均电位,离子配置文件,有效的表面相互作用和净离子电荷之间的墙壁。重点放在强约束电解质的限制,在这种情况下,在表面间空间的局部电中性可能不会得到满足。为了评估这种局部电荷中性的缺乏对具有调制电荷域的表面之间的离子诱导相互作用的影响,我们考虑了受限电解质的两个不同的模型系统:其中明确考虑盐储库{ \it via}与固定体积浓度的电解质的渗透平衡,第二种是隐含地考虑了与电荷中性离子库的平衡。虽然在前一种情况下,渗透离子交换可能会导致非零净电荷,在后一种模式中,通过在带电界面上出现隐含的唐南电位来强制执行电荷中性。在所有的粒子分离的离子诱导的表面相互作用在所采用的模型系统中观察到一个很强的依赖性。这些研究结果强烈表明,在选择不同的方案来描述带电表面之间的电解质中的离子交换时,即使在不存在非零净电荷(non-zero net charge)表面贡献的情况下,也要小心。
英文摘要:
In the present work, we study an electrolyte solution confined between planar surfaces with nonopatterned charged domains, which has been connected to a bulk ionic reservoir. The system is investigated through an improved Monte Carlo (MC) simulation method, suitable for simulation of electrolytes in the presence of modulated surface charge distributions. We also employ a linear approach in the spirit of the classical Debye-Hückel approximation, which allows one to obtain explicit expressions for the averaged potentials, ionic profiles, effective surface interactions and the net ionic charge confined between the walls. Emphasis is placed in the limit of strongly confined electrolytes, in which case local electroneutrality in the inter-surface space might not be fulfilled. In order to access the effects of such lack of local charge neutrality on the ionic-induced interactions between surfaces with modulated charge domains, we consider two distinct model systems for the confined electrolyte: one in which a salt reservoir is explicitly taken into account {\it via} the osmotic equilibrium with an electrolyte of fixed bulk concentration, and a second one in which the equilibrium with a charge neutral ionic reservoir is implicitly considered. While in the former case the osmotic ionic exchange might lead to non-vanishing net charges, in the latter model charge neutrality is enforced through the appearance of an implicit Donnan potential across the charged interfaces. A strong dependence of the ionic-induced surface interactions in the employed model system is observed at all particle separations. These findings strongly suggest that due care is to be taken while choosing among different scenarios to describe the ionic exchanging in electrolytes confined between charged surfaces, even in cases when the monopole (non zero net charge) surface contributions are absent.
Osmotic stress and pore nucleation in charged biological nanoshells and capsids
提出了一个模型系统,以调查的化学平衡和机械稳定性的生物球状纳米壳与水溶液中添加的解离电解质的给定浓度。在精确的密度泛函理论(DFT)的框架下研究了可渗透壳层上的离子化学平衡,该理论结合了传统平均场({ \it e. g.},Poisson-Boltzmann)极限。理论的准确性进行了测试与蒙特卡罗(MC)模拟的直接比较。一个简单的分析表达式,然后推导出清楚地突出了熵,静电,和自能贡献的渗透应力在壳的计算离子配置文件。通过调用一个连续平均场弹性的方法来解释渗透拉伸时的壳表面应力,各种各样的离子强度和表面电荷下的壳的机械平衡性能进行了研究。该模型进一步耦合到一个连续的机械方法类似的结构,经典成核理论(CNT),以解决问题的机械稳定性的壳孔成核。这使我们能够构建一个相图,该相图界定了不同离子强度和壳表面电荷的衣壳的机械稳定性。
Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation
在纳米尺度上离子传输的基本理解是必不可少的开发基于纳米孔技术和新一代高性能纳滤膜分离和纯化应用的生物传感器。我们在这里研究了离子通过具有高纵横比(长度L=6 μm,直径范围从1到10 nm)和具有良好控制的圆柱形几何形状的单个纯中性疏水纳米孔的传输。我们开发了一个详细的混合介观理论方法的纳米孔内的电解质电导率,明确考虑离子平流电渗流和可能的流动滑移在孔表面。通过拟合实验电导数据,我们表明,对于纳米孔直径大于4 nm的恒定弱表面电荷密度约10 $^{-2}$ C m $^{-2}$需要纳入模型中,以考虑在低盐浓度的几个皮西门子的电导平台。对于更紧密的纳米孔,我们的分析导致更高的表面电荷密度,这可以归因于靠近孔表面的离子溶剂化结构的改变,正如我们进行的分子动力学模拟中观察到的那样。
Charge Regulation Effect on Nanoparticles Interaction Mediated by Polyelectrolyte
Indian Institute of Technology Jodhpur(印度焦浦尔理工学院);University of Chinese Academy of Sciences(中国科学院大学);Institute of Physics, Chinese Academy of Sciences(中国科学院物理研究所);University of Ljubljana(卢布尔雅那大学)