Elastic interaction between force dipoles on a stretchable substrate

The objective of this paper is to study elastic interaction between force dipoles on the surface of a semi-infinite stretchable substrate. The substrate undergoes a uniform, finite pre-stretch, while the additional deformation induced by a force dipole is assumed infinitesimal. By adopting a neo-Hookean constitutive law, the surface Green function for the pre-stretched substrate is obtained. The result is then used to derive the energy of dipolar interaction on the surface. As an application, mutual interaction between two physisorbed molecules is discussed in detail. The dipole moment of a molecule is found from the elementary intermolecular potential, and its dependence on the pre-stretch is established explicitly. Numerical results indicate that pre-stretches can substantially alter the interaction, and thus provide a controllable way to guide the self-assembly of adsorbed molecules on the substrate surface.     

利用离子液体负载反应底物的有机合成

综述了固相、液相组合化学中以可溶性离子液体为载体的有机合成新概念及最新研究进展,并主要介绍了离子液体作为载体负载反应底物在有机合成中的一些应用,如有关的重要有机反应、组合化学、小分子库合成等。该方法具有上载率高、适用反应范围宽、分离纯化简便、结构检测容易和可回收重复使用等诸多优越性,这对于传统的固相、液相合成方法是一个重大的进步。     

球形主体分子的包结性能及其在制备有机非线性光学材料 中的应用

提出了球形主体分子的设计思想,把具有球形结构的分子柏木醇(1)、马钱子碱(2)、三乙烯二胺(1,4-二氮-二环[2.2.2]辛烷(3)作为主体分子,把酚类化合物,诸如苯酚(4)、邻甲苯酚(5)、间甲苯酚(6)、对甲苯酚(7)、对氯苯酚(8)和对硝基苯酚(11)等作为客体分子,进行了主客体分子相素作用实验,采用粉末X射线衍射、1^HNMR等分析手段确认了包结化合物的形成及主客体分子的摩尔比,摩尔比(H/G)分别为(1)+(4)1:1,(1)+(5)1:1,(1)+(6)1:1,(1)+(7)1:1,(1)+(11)1:2,(2)+(11)1:1,(3)+(4)1:2,(3)+(5)1:3,(3)+(6)1:2,(3)+(7)1:2,(3)+(8)1:2,(3)+(11)1:2,对典型包结化合物的单晶,诸如柏木醇和邻甲苯酚、马钱子碱和对硝基苯酚以及三乙烯二胺和对硝基苯酚,进行了四圆X射线衍射结构分析,结果表明,包结化合物的堆砌结构特征随主体分子的体积大小而改变,从隧道型如(1)+(5)和(2)+(11)转变为夹层型如(3)+(11)。用Nd:YAG激光测试晶体的SHG效应,结果表明,大部分包结物晶体具有非线性光学性质。     

两电子人造分子的能级结构

给出了相距为d的两个单电子圆盘量子点构成的人造分子的能级结构,讨论了能级随d,ω0(谐振子圆频率)及B(外磁场强度)变化的情况。     

Polar molecule dominated electrorheological effect

The yield stress of our newly developed electrorheological (ER) fluids consisting of dielectric nano-particles suspended in silicone oil reaches hundreds of kPa, which is orders of magnitude higher than that of conventional ones. We found that the polar molecules adsorbed on the particles play a decisive role in such new ER fluids. To explain this polar molecule dominated ER (PM-ER) effect a model is proposed based on the interaction of polar molecule-charge between the particles, where the local electric field is significantly enhanced and results in the polar molecules aligning in the direction of the electric field. The model can well explain the giant ER effect and a near-linear dependence of the yield stress on the electric field. The main effective factors for achieving high-performance PM-ER fluids are discussed. The PM-ER fluids with the yield stress higher than one MPa can be expected.     

光致变色液晶聚合物的光致再取向性能研究进展

光致变色分子经掺杂或键合作用嵌在液晶聚合物中可形成光致变色液晶聚合物,在线性偏振光或非偏振光的照射下,此物质中光致变色分子的构型变化会引起整个液晶分子的二维或三维光致再取向的形成,本文综述了光致变色液晶聚合物的光致再取向的近期研究进展.     

Molecular Dynamics of Pectin Extension

Summary: A pectin 10mer under constant pulling speed and constant force was studied using the atomistic simulations. Molecular dynamics (MD) with the Amber99 and Amber-Glycam04 forcefields were performed. The main result of the present Amber-based MD simulations is that the two plateaux of the experimental force- extension dependence for pectin can be explained by transitions between three conformational states of pectin monomer ring (first from a chair (⁴C₁) to boat conformation and second from boat to an inverted chair (¹C₄) conformation). A multi-state dynamical model of single biopolymer extension under external force was elaborated and applied to extension of polymers with three-state monomers relevant to pectin.