中国理论物理学家与生物学家结合的典范--回顾汤佩松和王竹溪先生对植物细胞水分关系研究的历史性贡献(下)

(上接 2 0 0 3年第 6期第 4 0 9页 )4　汤、王论文出现的主观与客观条件汤、王对植物生理学所作出的此一历史性贡献 ,是一位植物生理学家和一位理论物理学家合作的结果 .此一事实在一定的意义上表明 ,对于自然科学的某一特定领域一些基本问题的突破 ,根据问题所涉及知识领域的不同 ,往往是在多学科科学工作者的协作或具有不同专长的相同学科学者的合作下完成的 .自然科学史上这样的情况并不罕见 ,DNA双螺旋结构的创立是跨学科科学家协作的典型 ,低温超导中BCS理论的建立是同学科不同特长学者合作的范例 .汤、王二位先生能在 194 0年完成…     

记忆往往是靠不住的——对拙文“中国理论物理学家与生物学家结合的典范”的一处更正

2003年,我在《物理》发表了一篇文章,纪念我国理论物理学家王竹溪先生和生物学家汤佩松先生合作提出植物水势概念的历史功绩,文章的标题是《中国理论物理学家与生物学家结合的典范——回顾汤佩松和王竹溪先生对植物细胞水分关系研究的历史性贡献》,该文分(上)、(下)两部分分别刊登在2003年《物理》第32卷的第6期403—409页和第7期的477—483页.承读者和编辑部厚爱,这篇文章2005年经推荐曾获得第二届中国科协期刊优秀学术论文奖,并被一本书(杨舰、戴吾三编,《清华大     

The equivalent dipole potential of water for the electronic structure of threonine

The equivalent potential of water for the electronic structure of threonine (Thr) in solution is constructed by the first-principles, all-electrons, ab initio calculations. The main process of calculation consists of three steps. First, the geometric structure of the cluster containing Thr and water molecules is calculated by the free cluster calculation. Then, based on the obtained geometric structure, the electronic structure of Thr with the potential of water molecules is calculated using the self-consistent cluster-embedding method. Finally, the electronic structure of Thr with the potential of dipoles is calculated. The results show that the major effect of water on the electronic structure of Thr is to raise the occupied molecular orbitals near the Fermi level by about 0.01 Ry on average, and its energy gap is almost not changed. The effect of water on the electronic structure of Thr can be simulated by dipoles potential.     

How water and counterions diffuse into the hydrated montmorillonite

Molecular dynamics simulations have been performed to study the diffusive transport properties of water and counterions in 1-, 2- and 3-layer hydrated Wyoming-type montmorillonite (MMT). The considered counterions included in the clay are monovalent cations, such as Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and divalent cations, such as Ca²⁺, Ni²⁺, Zn²⁺ and Pb²⁺. The diffusion simulation results of Li-, Na-, K-, Cs-MMT, based on NVE ensemble and SPC/E water model, compared well to available experimental quantities and previous simulations, which permit us to study the diffusion behaviour of heavy metal counterion including in the different hydrated montmorillonite. Our simulation results show that the diffusion coefficients of both water molecule and counterions increase versus the quantity of water content. At the same hydrated state, the diffusion of cations strongly depends on their size, weight and capacity of attracting water. Monovalent cations diffuse always much faster than divalent ones. Although the increasing of hydrate degree can raise the diffusion coefficient of divalent heavy cations, the activity of these heavy counterions is still very weak. The diffusion of cations in the interlayer space of clay is much weaker than that in bulk water. That means the presence of charged clay has great influence on the diffusion of cations, which change totally the diffusion behaviour of cations.     

一个保守力作的功能等于势能的减少吗

通过实例说明一个保守力作的功,在一般情况下并不等于势能的减少,一个对保守力作用功才等于势能的减少。