van der Waals

In this article, Debye’s contributions to understanding van der Waals attractive forces, specifically, dipole-induced dipole interaction, is discussed. The Rg...HF complex structure is influenced by this interaction. Hence, these types of van der Waals molecules can be more specifically called Debye molecules.     

Molecule matters van der Waals molecules

van der Waals introduced his equation of state in 1867 modifying the ideal gas equation. His equation had two constants a and b, which accounted for the fact that molecules have attractive forces and finite size. The constant a accounted for the attractive forces, the nature of which was not outlined by van der Waals. This series of articles will discuss about the nature of intermolecular forces.     

范德瓦尔斯气体多方过程的研究

推导了范德瓦尔斯气体多方过程的P-V方程,然后推导用温度和熵表示的范德瓦尔斯气体多方过程的过程方程,由此得到范德瓦尔斯气体几种特殊的等值过程的过程方程.     

对范德瓦耳斯气体引力势能的一种谬论的深入分析

对范德瓦耳斯气体引力势能理解中的一种错误进行深入分析,根据统计的思想,用两种方法证明了范氏气体摩尔引力势能的表达式,并指出它的适用条件是短程弱引力分子气体;通过对比范氏固体和范氏气体引力势能的计算过程,揭示了谬论的错误所在;从概率论的角度分析了膨胀时气体引力势能变化量有别于固体的根本原因。     

氢键对物质性质的影响及应用

氢键不属于化学键,也不属于范德华力,是介于化学键和范德华力之间的一种由氢原子参与成键的特殊键型。氢键的键能较小,但其存在却对物质的性质,结构等方面有很大影响。故对氢键的研究应用也为人们所关注。     

Keesom力在分子间的作用

分子间存在的相互作用主要影响到一些物质的物理性质,Keesom力主要作用于极性分子和极性分子之间,对极性物质在水中的溶解度、熔沸点及吸附性和酸碱性均有影响,特别是极性很强的分子之间影响力更为突出,成为Vander Waals力的主要来源。     

19世纪人类有关语言本质问题的探索历程

19世纪,人类有关语言本质问题的认识,在已有语言工具论、符号论等有关理论继续得以向前发展的同时,又出现了语言世界观说、语言生物机体说,以及语言的本质在于交际等一些新的思想火花。     

高压下β硼电输运行为中的晶界效应

利用交流阻抗谱方法,讨论了高压下晶界效应对β硼电输运性质的影响,最高压力为28.3GPa.结果表明：晶粒电阻和晶界电阻均随压力逐渐减小;晶界电阻对总电阻的贡献随压力逐渐减小,当压力达23.9GPa时,随着范德瓦尔斯力及晶界相互作用的出现,晶界传导几乎消失.     

聚合物的溶解与选择性分子间引力

将控制论的结构适应性原理引入高分子学科，解释了一些范德华力、氢键等化学基本理论未能恰当解释的聚合物溶解现象。     

Molecular dynamics simulation of the interactions between EHD1 EH domain and multiple peptides

Objective: To provide essential information for peptide inhibitor design, the interactions of Eps15 homology domain of Eps15 homology domain-containing protein 1 (EHD1 EH domain) with three peptides containing NPF (asparagine-proline-phenylalanine), DPF (aspartic acid-proline-phenylalanine), and GPF (glycine-proline-phenylalanine) motifs were deciphered at the atomic level. The binding affinities and the underlying structure basis were investigated. Methods: Molecular dynamics (MD) simulations were performed on EHD1 EH domain/peptide complexes for 60 ns using the GROMACS package. The binding free energies were calculated and decomposed by molecular mechanics/generalized Born surface area (MM/GBSA) method using the AMBER package. The alanine scanning was performed to evaluate the binding hot spot residues using FoldX software. Results: The different binding affinities for the three peptides were affected dominantly by van der Waals interactions. Intermolecular hydrogen bonds provide the structural basis of contributions of van der Waals interactions of the flanking residues to the binding. Conclusions: van der Waals interactions should be the main consideration when we design peptide inhibitors of EHD1 EH domain with high affinities. The ability to form intermolecular hydrogen bonds with protein residues can be used as the factor for choosing the flanking residues.     

范德瓦尔斯频移及线型畸变现象

从理论上研究了囚禁于两电介质间薄原子蒸汽的频率调制吸收光谱中范德瓦尔斯频移及线型畸变现象,发现在频率调制情形下频移很明显,线型则由对称类色散型转为非对称类吸收型。采用频率调制的方法解决了在很多情形下采用直接法或吸收法不易实现对vdW作用势进行精确测量的难题。     

克劳修斯气体的热力学性质讨论

对克劳修斯气体的内能、摩尔热容量、临界参量作了研究,分析了该气体与范得瓦尔斯气体的差异.     

两种β-环糊精与冰片包结过程的动力学模拟

为研究冰片与β-环糊精(β-CD)或羟丙基-β-环糊精(HP-β-CD)包结机理,并解释冰片与两者的相溶解度关系,利用Accelrys公司开发的Materials Studio 4.0进行分子动力学模拟实验。在Compass力场下建立晶胞模型并进行恒温恒容(NVT)和恒温恒压(NPT)模拟得出能量图。两个能量图均显示发生包结作用的范德华力远大于氢键与疏水作用力之和,这证明冰片与环糊精发生包结作用的主要驱动力是范德华力。能量图显示:冰片与β-环糊精包结物的结合能低,而冰片与羟丙基-β-环糊精包结物的结合能高;故冰片与β-环糊精形成不溶性包结物,冰片与羟丙基-β-环糊精形成可溶性包结物。     

谈谈对气体的范德瓦耳斯方程中压强p的理解

本文将对准真实气体的范德瓦耳斯状态方程中压强p,提出作者的理解,并指出部分现行教材中对此问题阐述的不足之处。     

Atoms — How small, and how large!

The spatial extent of a free or an isolated atom can be gauged by defining its radius, and there are several different ways in which this quantity can be defined. Four of them are considered in this article. Quantum mechanical wave functions are employed to estimate the most probable and the average radii of atoms. Atomic polarizability radius and van der Waals radius are also considered, and all the four radii are examined across the periodic table. Atomic ions are then briefly dwelt upon, and a big contrast is noted in the sizes of (free) Li⁺ ion and the exotic H^? ion, both iso-electronic with helium atom. Brief mention is also made of large exotic species like the metastable atoms and Rydberg atoms. The article seeks to provide a quantitative glimpse of how small or large the atomic systems can be.     

On Attempting to Do What Lord Said Was Impossible: Commentary on van der Linden's “Some Conceptual Issues in Observed‐Score Equating”

van der Linden (this issue) uses words differently than Holland and Dorans. This difference in language usage is a source of some confusion in van der Linden's critique of what he calls equipercentile equating. I address these differences in language. van der Linden maintains that there are only two requirements for score equating. I maintain that the requirements he discards have practical utility and are testable. The score equity requirement proposed by Lord suggests that observed score equating was either unnecessary or impossible. Strong equity serves as the fulcrum for van der Linden's thesis. His proposed solution to the equity problem takes inequitable measures and aligns conditional error score distributions, resulting in a family of linking functions, one for each level of θ. In reality, θ is never known. Use of an anchor test as a proxy poses many practical problems, including defensibility.     

4-X-N-Y-6-氮杂雄-4-烯-3-酮衍生物的QSAR研究

分别采用人工神经网络BP算法（网络结构为3-9-1）和线性回归分析方法对17个4-X-N-Y-6-氮杂雄-4-烯-3-酮衍生物在4℃时与小牛子宫雌激素受体的亲合力参数Iog1/K（iKi为衍生物对3BHSD的抑制常数）与分子的范德华体积V、最高被占据分子轨道能量EHOMO和9号碳原子的净电荷Q之间建立了QSAR模型,ANN模型的相关系数R=0.9999,标准偏差SD=0.0014。MLR模型的相关系数R=0.9470,标准偏差SD=0.4459。结果表明人工神经网络是一种比较精密的拟合方法,具有良好的预测效果。     

Statistical Models and Inference for the True Equating Transformation in the Context of Local Equating

Based on Lord's criterion of equity of equating, van der Linden (this issue) revisits the so‐called local equating method and offers alternative as well as new thoughts on several topics including the types of transformations, symmetry, reliability, and population invariance appropriate for equating. A remarkable aspect is to define equating as a standard statistical inference problem in which the true equating transformation is the parameter of interest that has to be estimated and assessed as any standard evaluation of an estimator of an unknown parameter in statistics. We believe that putting equating methods in a general statistical model framework would be an interesting and useful next step in the area. van der Linden's conceptual article on equating is certainly an important contribution to this task.     

Subnormal osmolarity may underlie microcephaly in Zika viral infections

Leucines accounted for 9.144%of the Zika viral full length protein with over 300 leucines.The amino acid residue lacks γ methyl group,thus devoid of the σ-σ hyperconjugation in beta carbon,as well as strong van der Waals interactions with the carbonyl group of leucine.This results in the low cation affinity with carbonyl oxygen,and un-enhanced secondary chemical bonding with the oxygen atom.The subnormal osmolarity generated in the presence of leucine rich proteins and degraded peptides would affect the development of the brain.A carbohydrate diet could be effective in the prevention of viral infections.     

席夫碱铜配合物合成及与DNA/蛋白质作用的研究

利用2-吡啶甲醛、N,N-二甲基乙二胺制备了一种新的席夫碱铜配合物,并通过X-射线单晶衍射、元素分析和ESI-MS对其结构进行分析.晶体结构分析表明,配合物呈现扭曲的四方锥构型.用紫外-可见吸收光谱、荧光光谱和圆二色光谱研究了配合物与小牛胸腺DNA(CT-DNA)和人血清白蛋白(HSA)的结合性质.结果表明:配合物以插入的方式与DNA相互作用,且配合物与HSA的相互作用为静态猝灭机制,分子间作用力为氢键和范德华力.