几种热塑性特种工程塑料的热分析研究

聚芳醚和聚芳硫醚两类聚合物都为热塑性的耐高温特种高分子材料 ,由于它们的加工性好、加工成型效率高 ,受到了世界各国的高度重视。这两类聚合物在结构上有许多相似之处 ,如它们的主链都含苯环、酮基或砜基 ,而聚芳醚类聚合物的柔性基团为醚键 ,聚芳硫醚类聚合物的柔性基团为硫醚键 ,但由于氧和硫在元素周期表中属于同一族元素 ,原子结构仍然相似 ,因而在某些方面具有一定的可比性。研究它们的性能差异对于改进聚合物性能以及进行进一步的结构设计将有一定的帮助。在这两类聚合物中 ,国内已商品化生产的品种有ＰＥＥＫ、ＰＥＳ和ＰＰＳ ,有…     

Cu-Ce/γ-Al2O3对硬脂酸催化水热脱氧产生烷烃的效果

利用等体积浸渍法制备Cu-Ce/γ-Al₂O₃催化剂，并在无H₂存在的条件下对硬脂酸进行催化水热液化。对催化剂进行BET比表面积分析和X射线衍射（XRD）分析可知，Cu-Ce/γ-Al₂O₃催化剂中存在CuO和CeO₂两种晶型，在300℃条件下水热反应12 h后具有更好的热稳定性。通过对硬脂酸进行水热液化实验和对生物油进行气相色谱-质谱（GC-MS）分析发现，加入Cu-Ce/γ-Al₂O₃催化剂能够获得最高的硬脂酸转化率（94.71%）和总烃产率（81.41%），水热液化脱氧效果最好。分析正烷烃的产率，结果发现硬脂酸在高温水热条件下主要发生脱羧反应。Cu-Ce/γ-Al₂O₃催化剂的加入能够同时促进反应过程中脱羧反应、加氢脱氧反应和裂化反应。此外，Cu-Ce/γ-Al₂O₃还能够促进羰基基团的脱除，有效减少产物中的醛和酮类物质。     

IDENTIFICATION OF PARTIAL MUTATIONAL SITES IN HUMAN MITOCHONDRIAL DNA IN THE CHINESE AND ITS SIGNIFICANCE

A simple method for the identification of mutational sites in human mitochondrial DNA (mtDNA) was described. It was based on the human Cambridge sequence as a relative standard sequence and a single base pair substitution in mtDNA as a unique mutational form. The partial mutational sites can be determined using this method which was characterized by combining the restriction mapping with the analysis for the table of human mtDNA potential mutational sites with rapidity and simplicity. In the meanwhile, six mtDNA mutational sites found in Chinese population were identified by means of this method.     

CARBON-13 NMR STUDY OF MOLECULAR MOTION OF 1, 2-POLYBUTADIENES IN SOLUTION Ⅰ. STRUCTURE DEPENDENCE OF MOLECULAR MOTIOM

Proton decoupled, partially relaxed, Fourier-transform 50.3 MHz carbon-13 NMR in naturalabundance was used to determine spin-lattice times (T_1) and nuclear Overhauser enhancement fac-tors (NOE) of individual carbon of a serics of 1,2-polybutadienes with different structures in solutionin CDCl_2 The structure dependence of molecular metion and the internal motion of vinyl group in1,2-polybutadiene have been studied by nT_1 and NOE values. The nT_1 values of the carbons in cis-1,4-units are the highest and those of the carbons in 1.2-units are the lowest in three types of units in1,2-polybutadiene. The nT_1 values of carbons in the same unit become greater when the adjacent1,2-units are replaced by 1,4-units, and nT_1 values of the carbons in all units decrease sharply withthe increase of content of 1,2-units in the polymers. The fact that nT_1 values of --CH=are larger than those of=CH_2 in vinyl group impliesthat there are complex internal motions of vinyl group. It is shown by calculation that the dominantfactor causing the difference in nT_1 of--CH=and=CH_2 in vinyl group is a swing of vinyl group ina plane peopndicular to the chain backbone.     

DFT Investigations About Pyrazine Molecules on Si(100)-2×1 Surface

It is important to understand the interface of aromatic molecules on semiconductor surfaces because of the rich functionality of such molecules on semiconductor surfaces. The chemisorption of pyrazine molecules on the Si( 100)-2×1 surface has been investigated using the B3LYP density functional theory with Si9H12 one-dimer and Si15H16 twodimer cluster models. The calculated results predict that N-dative bonded-state, C2= C5 [ 4 2 ] and the tightbridge1, 2, 5,6 products may coexist on the Si(100)-2×1 surface.     

新型四硫代富瓦烯衍生物的合成及其性质的研究

合成了3个新的含有卤素取代基的四硫代富瓦烯衍生物及6个新的相关化合物。利用溶液的电子吸收光谱对四硫代富瓦烯衍生物的性质进行了研究。研究结果表明, 四硫代富瓦烯衍生物的分子中π轨道之间的能级差较小, 因而分子具有较高的稳定性。     

基于SnO2为修饰层的Au-Pt / SnO2 / Au复合电极研究

用真空镀膜法在Au电极上沉积SnO₂薄膜，在HAuCl₄和H₂PtCl₄的混合溶液中利用直接还原法，将Au-Pt双金属纳米颗粒组装在SnO₂ / Au电极上，得到Au-Pt / SnO₂ / Au复合电极。采用SEM、TEM、XPS及CV曲线测定对Au-Pt / SnO₂ / Au复合电极进行了表征。结果表明:复合电极上双金属纳米颗粒分布均匀，粒子粒径约为25 nm左右。SnO₂作为修饰层以配位键与双金属纳米粒子结合。Au-Pt / SnO₂ / Au复合电极具有良好对甲醇氧化的电化学性能。     

IMMOBILIZATION OF POTENTIALLY BIOACTIVE MOIETIES ONTO POLYETHER WITH POLY(ETHYLENE GLYCOL)-SULFONATE SPACER

A new reactive graft copolymer, poly(tetramthylene glycol) - graft-w-propyl sodiumsulfonate-poly(ethylene glycol) (PTMG-g-PEG-CH_2CH_2CH_2SO_3~-Na~+), was synthesizedby the cationic polymerization of a-w-bifunctional PEG macromonomer (O?CH_2—PEG——CH_2 CH_2 CH_2 SO_3 Na) and THF. The obtained copolymer exhibits the expected structureas indicated by the result of characterization. Two amino acids (L-arginine, L-tyrosine)were covalently attached to the copolymer after converting the sulfonate group to sulfonylchloride. So the new reactive graft copolymer (PTMG-g-PEG-CH_2CH_2CH_2SO_3~-Na~+) isexpected to be very useful in attachment of potentially bioactive moieties to polymer viaa hydrophilic PEG spacer.     

二茂铁亚胺环钯化合物－－一种新型芳基氯化汞偶联催化剂

发现在催化量二茂铁亚胺环钯化合物催化下，芳基氯化汞可在湿和条件下偶联 ，以中等或高的收率生成联芳烃。对于铑盐不能催化偶联的邻位取代苯基氯化汞和 α－基氯化汞，在此体系中亦可发生偶联。以HMPA为溶剂，在x = 0.025（摩尔分 数）化合物1或2催化下与2.0当量氯化锂存在时，得到最好的催化效果。     

Theoretical Study on the Isomerization Mechanism of Enol Ester from 2-Acyl-1, 3-cyclohexanediones

The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step.