Computational dynamics method for evaluating the mobility of charged biomolecules passing through the electrical potential field within the ion selective channel on an excitable membrane

A mathematical method is introduced to characterize the electrokinetic behavior (electrophoresis) of a biomolecular particle which passes through a specific channel pore on an excitable biological membrane. The basic approach was first proposed by Booth (1950). The system was described by an equation of continuity and an equation of motion in which the driving force involves the diffusion effect, the hydrostatic pressure, and the electrostatic potential. By assuming linear relations between the velocity and the applied electrical field, solutions for the potential, pressure, and velocity were given by a series expansion of the charges on the particle. To examine the influence of ions surrounding the particle and forming an ionic cloud, the Debye–Huckel parameter was introduced. As the thickness of the double layer around the particle increased, the potential, velocity, pressure, and viscosity were changed significantly. The maximum influence was obtained when the radius of the particle became equal to the thickness of the double layer. Although this theory is valid for a charged, spherical, nonconducting particle only, the method is available for evaluating the kinetic behavior of a biomolecule that passes through a channel pore on a cellular membrane.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

茶乳酪分子间氢键与抗过敏分子轨道研究

应用CNDO／2法研究茶乳酪分子间氢键与抗过敏性的关系．结果表明执过敏性与条乳酪HOMO能量有正变关系。分子间氢键可增加茶环与嘌呤环的共平面。PMO分析表明共平面性可使HOMO具有较高能量,故认为条乳酪可能以电子给予体的形式与酶作用,是茶乳酪产生显著生物学效应的基本条件。     

HMO法及其在有机化学中的应用

HMO法是分子轨道法中一个简化的近似计算方法。它主要应用于共轭分子。由于HMO法比较简单,并且从中还可提供一些有用的物理图象便于直观讨论结构和性能的关系,故为有机化学工作者易于接受。在此,本文将介绍HMO法的基本原理,并结合当前有机化学的教学来说明它在某些方面的应用。     

A substitution of nickel by antimony:: Crystal and electronic structure of the new antimonide Hf6Ni1−xSb2+x

The ternary antimonides Hf₆M_1−xSb_2+x (M=Fe, Co, Ni) were prepared by arc-melting of stoichiometric mixtures of Hf, HfSb₂ and M. According to the single crystal structure analyses, performed on Hf₆NiSb₂ and Hf₆Ni_0.76Sb_2.24, Hf₆M_1−xSb_2+x crystallizes in an ordered variant of the Fe₂P structure type with the M and Sb atoms occupying the two P positions on 1b and 2c of space group P

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2m, respectively (Zr₆CoAl₂ type). The 3d metal atoms M can partially be replaced by antimony, leading to significant, anisotropic changes in the lattice dimensions which are a=765.6(1) pm, c=362.10(7) pm, V=183.81(5)×10⁶pm³ for Hf₆NiSb₂, and a=760.5(1) pm, c=372.40(7) pm, V=186.53(5)×10⁶pm³ for Hf₆Ni_0.76Sb_2.24 as determined by single crystal data. Calculations of the electronic structure of Hf₆NiSb₂ using the Extended Hückel approximation show strong bonding Hf–Hf, Hf–Ni, and Hf–Sb interactions.     

烷基芳烃易发生α-卤代反应浅析

本文应用休克尔分子轨道(HMO)理论,计算了α,β自由基分子轨道的能量,比较了它们的稳定性,进而说明了α-卤代反应优先发生的原因。