Modelisation of the Electric Field Linear Response of an Infinite Aggregate of All-Trans Hexatriene Chains by Electrostatic Interaction Model

A classical electrostatic polarization scheme using the additive distribution procedure has been applied to determine the longitudinal polarizability of an all-trans hexatriene molecule in an infinite stretched fiber. The parameters have been derived from ab initio CPHF/6-31G calculations and the electrostatic scheme has been validated via comparison with ab initio results on small clusters. Upon packing the polarizability of all-trans hexatriene increases by 7%. This small increase results from the balance between the enhancement of the polarizability due to collinear packing and the reduction associated with lateral packing.     

New crystal structures of β-[Ni(NCS)2(4-methylpyridine)4] clathrates with furan,tetrahydrofuran, methylene chloride,benzene + ethanol and methylcellosolve as guest molecules

Single crystal X-ray structures of clathrates of -[Ni(NCS)₂(4-methylpyridine)₄] with furan, tetrahydrofuran, benzene + ethanol, methylene chloride, and methylcellosolve as guests molecules are reported. The location of the guest molecule in the partially decomposed clathrate with methylene chloride was defined by X-ray diffraction and compared with the fully occupied one. The host lattices of all clathrates studied are tetragonal (I4₁/a) and do not differ significantly from typical -phase clathrates of [M(NCS)₂(4-methylpyridine)₄] (M = divalent metal cation). Arrangements of guest molecules represent different types of packing: one type of guest molecule occupies both possible types of positions, two different guest molecules occupy different positions, with only one type of positions occupied by one type of guest molecule. Possible stoichiometries of clathrates with -type lattices are discussed.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August 1995.     

有限型的首次返回例外集的测度和维数北大核心CSCD

设M=(m_(ij))是一个b×b阶矩阵且m_(ij)∈{0,1},∑_(M)是矩阵M=(m_(ij))诱导产生的有限型,σ是其上左推移算子.本文主要研究的是有限型动力系统(∑_(M),σ)上的首次返回速度问题.令τ_(k)(x)是点x∈∑_(M)首次返回到包含x的k阶柱集时间,且E_(α,β)={x∈∑_(M):lim inf_(k→∞)(logτ_(k)(x))/k=α,lim sup_(k→∞)(logτ_(k)(x))/k=β}.我们证明了:当M是不可约矩阵时,对任意0≤α≤β≤+∞,集合E_(α,β)的Markov测度要么等于0要么等于1并且具有满的Hausdorff维数.     

有阻尼Sine－Gordon方程的全局吸引子的维数

本文通过引入新范数,得到有阻尼Ｓｉｎｅ－Ｇｏｒｄｏｎ方程的Ｄｉｒｉｃｈｌｅｔ问题的全局吸引子的维数的一个估计．结果表明：当“阻尼”与“扩散”同时增大或正弦项系数减小时,吸引子的维数减小．特别地,得到了零维吸引子存在的参数条件．     

Microporous hypercrosslinked polystyrene Styrosorb as a restricted access packing in sample clean-up for high performance liquid chromatography. Part I: Evaluation of restricted access properties

Summary Styrosorb is a beaded microporous polystyrene with particle sizes between 2 and 4 m. In spite of hypercrosslinkage the material was seen to swell in organic solvents. The native material is functionalized with Tris-groups at the outer surface of the particles. The average pore diameter was determined as 1.45±0.3 nm from size exclusion data using polystyrene and polyethylene standards in THF. The reversed phase behavior of the restricted access phase Styrosorb was investigated by injection of two test mixtures. Mixture I contained five aromatic amines, mixture II consisted of Amperozide^R and four related compounds. The optimum range of mobile phase composition was assessed so that analytes were separated whilst any proteins present were eluted unretained. Due to the small particle size short columns of 29×4 mm can be used for both sample clean-up and analytical separation of Amperozide^R and its metabolite.     

Diffusion in a one-dimensional gas of hard point particles

We simulate the classical diffusion of a particle of massM in an infinite one-dimensional system of hard point particles of massm in equilibrium. Each computer run corresponds to about 10⁸ collisions of the diffusive particle. We find that (t) 1/t fort large enough, and a crossover from an M m regime where=2 to=3 forM=m. The diffusion constant has a sharp maximum atM=m. We study moments x(t)² and x(t)⁴, and examine the behavior ofq ² (t)=x(t)⁴/3x(t)²². We find thatq(t)1 (consistent with a normal distribution) in theM limit (for all timest) and in the t limit for allM. On sabbatical leave from IVIC-Instituto Venezolano de Investigaciones Cientificas.     

胺型键合反相固定相的制备及评价

首次将一种新型硅烷偶联剂--β-（3，4-环氧环已基）乙基三甲氧基硅烷（β-ECTS）与辛胺反应，然后再键合到硅胶上，得到了胺型键合固定相，并用元素分析、^13C固体核磁共振、红外光谱进行了表征。以甲醇和水为二元流动相，用包括碱性、酸性和中性有机化合物在内的混合物对该固定相进行评价，并考察了该填料的适用pH范围及水解稳定性。结果表明，该固定相具有较好的色谱性能，且在pH=2-8之间稳定性能良好，可有效地用于碱性化合物的分析分离。     

反相液相色谱用球形共聚物柱填料

采用新颖聚合工艺制备用于反相高效液相色谱柱填料的乙基苯乙烯-二乙烯苯球形共聚物,不需使用备有高速搅拌的混匀器和特殊的筛析设备,聚合物粒径的95％在3～7μm之间,测算了渗透性、柱效和峰不对称性等柱参数,并通过分离实例说明该填料对胺类、酚类和芳烃类具有优良分离性能。     

The mean spherical model in a random external field and the replica method

We provide a quick elementary solution of the mean spherical model in a random external field. This also allows an immediate proof of the self-averaging property of the free energy. We calculate the free energy by means of the replica method, i.e., for any (not necessarily integer) replica numbern, and show that when a phase transition occurs the limits andn 0 are not interchangeable.     

EXAMINATION OF THE SURFACE FREE ENERGY AND ACID-BASE PROPERTIES OF CELLULOSE BY THE COLUMN WICKING TECHNIQUE AND THE CRITICAL PACKING HEIGHT/DENSITY

INTRODUCTIONThe wicking technique has been used to determine the surface energy components of solids[1-7]. Generally, thereare two wicking processes in practice, i.e. thin layer wicking and column wicking. A comparison of the twowicking techniques made by van Oss et al.[2], shows that column wicking has a problem of showing differentpacking density due to some kinds of powder materials, i.e. clay can not give good repacking reproducibility[2].But thin layer wicking has a problem in sample…