有机化合物结构自动解析专家系统研究

本文建立了一个能用于含N、P、O、S、Si及卤素等多种杂原子的有机化合物结构自动解析专家系统ESESOC(Expert System for the Elucidation of the Structure of Orsanic Compounds)。它可从未知化合物的分子式、光谱数据(包括IR, MS，~1HNMK ~(13)CNMR, 2D-NMR等)及其它化学信息自动地推衍出与己知信息相一致的候选化合物结构。ESESOC系统由三个部分组成：(1)光谱知识库及其光谱解释模块；(2)结构产生器；(3)结构验证模块。其结构解析基本过程为：从分子式、光谱数据或其它化学信息出发，由未知化合物的光谱数据去检索光谱知识库，即进行数据分析并推断出该未知化合物中可能含有的结构碎片，然后由结构产生器从这些结构碎片进行候选化合物结构的穷举生成，最后对候选结构进行验证并输出结果。从而实现由化合物光谱数据鉴别未知化合物结构的自动化。结构产生器是系统的核心模块。对一个结构产生器的基本要求是：穷举性，非冗余性，有效性。要完成一个能实际使用的结构产生器，效率则是至关重要的。ESESOC系统生成结果的穷举和非冗余性己通过与图论计算结果及著名的DENDRAL系统的生成结果相比较得以证明。如由本系统生成的烷烃系列C_nH_(2n+2)，及醇、醚系列C_nH_(2n+2)0的异构体数目与图论理论计算的数目相同；对C_5H_n n = 12，10，8，6，4，2，O；C_6H_n n = 14，12，lO，8，6，4，2，O系列，及含多种杂原子(O、N、S等)的复杂体系，其异构体生成结果则与DENDRAL系统的生成结果完全一致(DENDRAL系统的结构生成算法是经数学证明了是正确的，其结果已被很多系统引为穷举和非冗余性的例证)。关于ESESOC系统的有效性，在同一计算机上测试结果表明ESESOC系统的结构生成效率比著名的日本的CHEMICS系统高很多倍。结构解析专家系统另一重要组成部分为谱图知识库，它是逻辑推理的基础。专家系统的效能取决于其子结构一子光谱相关的知识库的有效性，所以要建造一个有效的~(13)CNMR知识库，关键在于建立一个好的子结构模型．在~(13)CNMR知识库中，子结构的概念与常规的子结构概念有所不同，它包括两个组成部分，(1)中心原子，它对应于一个化学位移；(2)环境部分，结构环境决定了中心原子的化学位移峰的位置。子结构模型的选择要适当兼顾信息全面和防止“组合爆炸”两个因素。ESESOC系统从~(13)CNMR本身的特征出发，提出了不确定层数的子结构模型。即以共振碳原子为中心，以与之相连的完整的官能团为外围环境，对这样的子结构，其外围环境根据官能团的不同可以是一层、或二层乃至多层，即环境层数是可变的。此即为ESESOC系统的广义-层子结构模型，它具有包含结构信息全，所有可能存在的子结构数量适中等优点。在此子结构模型的基础上，从CIAC-~(13)CNMR谱图数据库统计出。~(13)CNMR知识库，即子结构-~(13)CNMR化学位移相关表。ESESOC系统中结构验证方法有： ~(13)CNMR谱峰数预测，~(13)CNMR波谱模拟，应力能计算等。在结构解析专家系统研究中还涉及到如下三个问题：(1)结构编码；(2)结构之间相互比较；(3)结构中原子的对称性分析。在本研究中，对这些问题都提出了新的方案，并均获得较好结果。(1)在建造化合物结构信息系统时，首先要解决化合物结构的计算描述，即结构编码问题，以进行化合物结构的计算机存储和管理。为此我们提出了两种新的拓扑指数编码方案，即ID指数和EAID指数。由ESESOC结构产生器穷生成了含1-22个碳原子的380多万个链烷烃异构体，含1-12四价碳原子的20多万仑复杂多环异构体及40多万个含杂原子的化合物，通过对这3个系列共440多万个化合物结构的验证，结果表明，ID和EAID指数对这440多万个化合物结构均能唯一地区分，即没有出现简并(简并是指两个或多个不同的结构具有相同的拓扑指数值)。这是迄今未见报道的。(2)在计算机结构信息处理中，最常遇到的一个问题就是确认一个结构是新结构还是为已知结构，这就要把该结构与库中的结构进行逐个比较。为了结构的比较，我们以二维连接表描述化合物的结构，因连接表随化合中原子的编序的变化而变化，因而就需要有一套序号赋值规则，无论结构图在画法或形状以及原子的序号上如何变化，都可使得结构图中的各原子按该规则得到唯一的排序方案。ESESOC系统的唯一性序号方案集中了Morgan算法及其改进方案之所长，并加入新的图的不变量，如最小环指数等以正确地划分分子中的原子，从而得到一个新的唯一性排序方案，该方案效率较高，可适用于各类复杂化合物。在ESESOC系统中，我们还以一维的整数数组来存贮和管理二维连接表，即得到压缩连接表，这在结构比较时大大地节省了系统开销，提高了比较速度。在同一结构中，若各原子由两种不同编序方案得到同一连接矩阵，则与某一序号所对应的两个原子所在结构图中的拓扑环境是等价的，也就是说两个节点是拓扑等价的，或具有拓扑对称性(Topological Symmetry)。化合物结构中原子的唯一性排序算法，有机化物结构异构体穷举生成过程中冗余对接的消除，NMR谱模拟等都与拓扑对称性密切相关。在ESESOC系统建造过程中，我们提出了三个新的拓扑等价性分析算法，它们是基于节点矩阵的拓扑等价性算法，基于全通道算法的拓扑等价性算法，以及基于扩展连接矩阵算法的拓扑等价性算法。这些算法结果准确，效率高，适用于各类化合物。

ELECTROCHEMICAL STUDY OF ISOPOLY AND HETEROPOLY ANION TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE .2. VANADIUM-CONTAINING HETEROPOLYTUNGSTATE ANIONS

The electrochemical transfer behaviour of vanadium-containing heteropolytungstate anions [PW12-xVxO40]((3+r)-) (x = 1-4) across the water \nitrobenzene interface has been investigated by cyclic voltammetry and chronopotentiometry with cyclic linear current scanning. The transfer of PW11V1O404-, HPW10V2O404-, H2PW10V2O403-, H3PW9V3O403- and H4PW8V4O(40)(3-) across the water \nitrobenzene interface can be observed within the potential window. The effects were observed of pH in the water phase on the transfer behaviour and the formation of vanadium-containing heteropolytungstate anions in solution. Heteropolytungstate anions become more stable due to their involving the vanadium atom. The degree of protonation and the dissociation constant of the trivalent vanadium-containing heteropolytungstate anion of protonation increase with increasing vanadium content. The transfer processes are diffusion-controlled The standard transfer potential, the standard Gibbs energy and the dissociation constant for vanadium-containing heteropolytungstate anions have been obtained and the transfer mechanisms are discussed.

Molecular characterisation and inductive expression of a fish protein arginine methyltransferase 1 gene in response to virus infection

Protein arginine methyltransferase 1 (PRMT1) is currently thought as an effector to regulate interferon (IFN) signalling. Here Paralichthys olivaceus PRMT1 (PoPRMT1) gene was identified as a vitally induced gene from UV-inactivated Scophthalmus maximus Rhabdovirus (SMRV)-infected flounder embryonic cells (FEC). PoPMRT1 encodes a 341-amino-acid protein that shares the conserved domains including post-I, motif I, II and III. Homology comparisons show that the putative PoPMRT1 protein is the closest to zebrafish PMRT1 and belongs to type I PRMT family (including PRMT1, PRMT2, PRMT3, PRMT4, PRMT6, PRMT8). Expression analyses revealed an extensive distribution of PoPMRT1 in all tested tissues of flounder. In vitro induction of PoPRMT1 was determined in UV-inactivated SMRV-infected FEC cells, and under the same conditions, flounder Mx wash also transcriptionally up-regulated, indicating that an IFN response might be triggered. Additionally, live SMRV infection of flounders induced an increased expression of PoPRMT1 mRNA and protein significantly in spleen, and to a lesser extent in head kidney and intestine. Immunofluorescence analysis revealed a major cyptoplasmic distribution of PoPRMT1 in normal FEC but an obvious increase occurred in nucleus in response to UV-inactivated SMRV. This is the first report on in vitro and in vivo expression of fish PRMT1 by virus infection, suggesting that PoPRMT1 might be implicated in flounder antiviral immune response. (c) 2006 Elsevier Ltd. All rights reserved.

Effects of rapid thermal annealing on the emission properties of highly uniform self-assembled InAs/GaAs quantum dots emitting at 1.3 mu m

The authors report the effects of rapid thermal annealing (RTA) on the emission properties of highly uniform self-assembled InAs quantum dots (QDs) emitting at 1.3 mu m grown on GaAs substrate by metal organic chemical vapor deposition. Postgrowth RTA experiments were performed under N-2 flow at temperatures ranging from 600 to 900 degrees C for 30 s using GaAs proximity capping. Surprisingly, in spite of the capping, large blueshifts in the emission peak (up to about 380 meV at 850 degrees C) were observed (even at low annealing temperatures) along with enhanced integrated photoluminescence (PL) intensities. Moreover, pronounced peak broadenings occurred at low annealing temperatures (< 700 degrees C), indicating that RTA does not always cause peak narrowing, as is typically observed with traditional QDs with large inhomogeneous PL linewidths. The mechanism behind the large peak blueshift was studied and found to be attributed to the as-grown QDs with large size, which cause a larger dot-barrier interface and greater strain in and near the QD regions, thereby greatly promoting Ga-In intermixing across the interface during RTA. The results reported here demonstrate that it is possible to significantly shift the emission peak of the QDs by RTA without any additional procedures, even at lower annealing temperatures. (c) 2007 American Institute of Physics.

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4 '-bipy)(H2O)4](4-abs)2 center dot nH(2)O (4,4 '-bipy=4,4 '-Bipyridine; 4-abs=4-aminobenzenesulfonate) (M=Co, n=1; M=Mn, n=2)

Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

荧光衍生试剂1-[2-（对甲苯磺酸醋）乙基]2-苯基咪唑[4,5-f]9,10-菲的合成及其在长链脂肪酸分析中的应用

合成了新的荧光衍生试剂1-[2-（对甲苯磺酸酯）乙基]-2-苯基咪唑[4,5-f]9,10-菲（TsEPIP），并将其作为柱前衍生化试剂，在Eclipse XDB-C：色谱柱上采用梯度洗脱实现了11种长链（C_(20)～C_(30)）游离脂肪酸（FFA）衍生物的基线分离。利用柱后在线的串联质谱并以大气压化学电离源（APCI）的正离子模式实现了各组分的质谱定性。对土壤及3种苔醉（东亚毛灰鲜、锦丝鲜、羽平鲜）中FFA组分的定量结果表明，苔鲜植物从土壤中富集了大量的长链游离脂肪酸。荧光检测的激发波长和发射波长分别为260 nm和380 nm。线性回归系数大于0.9996，检测限为26.19～76.67 fmol。所建立的方法具有良好的重现性，对实际样品的测定结果令人满意。

The active sites in different TS-1 zeolites for propylene epoxidation studied by ultraviolet resonance Raman and ultraviolet visible absorption spectroscopies

The titanium species in four kinds of titanium-containing MFI zeolites have been studied by ultraviolet (UV)-Raman and ultraviolet visible (UV-Vis) absorption spectroscopies and by the epoxidation of propylene with diluted H2O2 solution (30%). UV-Raman spectroscopy is proved to be a suitable means to estimate qualitatively the framework titanium in TS-l zeolites. Based on the comparison of the relative intensity ratio I-1125/I-380 of UV-Raman spectra, the TS-1(conv.) sample synthesized hydrothermally by the conventional procedure shows the highest amount of framework titanium. UV-Vis spectroscopy reveals that besides minor anatase. titanium species are mainly tetrahydrally coordinated into the framework for TS-l(conv.) or the Ti-ZSM-5 sample prepared by gas-solid reaction between deboronated B-ZSM-5 and TiCl4 vapor at elevated temperatures. For the TS-1(org.) and TS-1(inorg.) samples synthesized hydrothermally using tetrapropylammonium bromide (TPABr) as template and tetrabutylorthotitanite (TBOT) and TiCl3 as titanium source, respectively, the presence of mononuclear and isolated TiOx species which are proposed to bond to the zeolite extraframework is observed. In addition to the framework titanium species, these isolated TiOx species are assumed to be also active for propylene epoxidation.