青蒿乙素的化学转化

本文报道青蒿乙素(2)的若干化学转化,如:青蒿乙素的催化氢化得到三个化合物5,6,7.6与三氟化硼-乙醚配合物反应生成8和9.6用硷水解以及2,6,7分别与五羰基铁进行脱氧反应,得到相应的化合物18,3和4。     

1MeV Si+衬底加温注入Al0.3Ga0.7As/GaAs超晶格和GaAs的晶格损伤研究

用卢瑟福背散射／沟道技术研究了１ＭｅＶＳｉ⁺在衬底加温和室温下以不同剂量注入Ａｌ_0.3Ｇ_0.7Ａｓ／ＧａＡｓ超晶格和ＧａＡｓ后的晶格损伤。在衬底加温下，观察到Ａｌ_0.3Ｇａ_0.7Ａｓ／ＧａＡｓ超晶格和ＧａＡｓ都存在一个动态退火速率与缺陷产生速率相平衡的剂量范围，以及两种速率失去平衡的临界剂量。超晶格比ＧａＡｓ更难以损伤，并且它的两种速率失去平衡的临界剂量也大于ＧａＡｓ中的相应临界剂量，用热尖峰与碰撞模型解释了晶格损伤积累与注入剂量和衬底温度的关系。用ＣＮＤＯ／２量子化学方法计算了ＧａＡｓ和Ａｌ_xＧａ_1-xＡｓ中化学键的相对强度，并根据计算结果解释了注入过程中Ａｌ_0.3Ｇａ_0.7Ａｓ／ＧａＡｓ超晶格和ＧａＡｓ中晶格损伤程度的差别。 关键词：     

PSORALEN-PHOTOSENSITIZED DAMAGE OF RAT PERITONEAL EXUDATE CELLS

Psoralen-sensitized photodamage (PUVA) of rat peritoneal exudate cells was investigated. Quartz-activated luminol-dependent chemiluminescence (ChL) was registered and the amount of trypan-positive cells was determined. Irradiation of peritoneal exudate cells in the presence of psoralen resulted in a dose-dependent monotonous inhibition of ChL. The reciprocity law of irradiation intensity and duration of irradiation was not valid for the observed inhibition of ChL: the inhibition increased with higher intensity. When psoralen previously photooxidized in ethanol (POP) was added to peritoneal exudate cell suspension, a double-phase response depending on psoralen irradiation dose was obtained: ChL activation was observed at low doses of UVA, ChL inhibition at high doses. Chemiluminescence inhibition correlated well with the increase in the number of trypan-positive cells. It may be supposed that the observed effects of PUVA or POP treatment are caused by cell cytoplasmic membrane damage.     

EXPRESSION OF A PARTIAL SYNTHETIC HUMAN TNF cDNA IN E. coli

A recombinant human tumour necrosis factor (rhTNF) cDNA was constructed. The TNF gene was isolated from a human genomic gene library. There are four exons in the TNF gene. The fourth exou codes for 140 amino acids of the TNF matured protein which is composed of 157 amino acids. A major portion of the fourth exon was isolated and then ligated to a synthesized DNA fragment coding for the remaining amino acids. The partial synthetic hTNF (rhTNF) cDNA thus generated was subcloned into a vector and successfully expressed in E. coli. 5-1 fer1entator was used to produce rhTNF. About 20g (wet weight) of bacterial pellet per liter medium and 106—10~7 units of cytotoxicity to L929 cells per milliliter medium were obtained. rhTNF was purified by HPLC and dried with a freeze dryer, rhTNF with a purity of about 95% in the form of white powder was obtained. The sequence of ten amino acids at the amino terminus of the rhTNF was determined. The result showed that it was identical with that of the natural human TNF.     

溶胶浸渍模板法制备有序多孔氧化钛、氧化锌薄膜

采用溶胶浸渍模板法制备了有序多孔的氧化钛(TiO₂)和氧化锌(ZnO)薄膜。首先，在洁净的玻璃基片上通过浸渍-提拉工艺组装有序的聚苯乙烯微球(PS)阵列模板；然后再采用溶胶浸渍法将TiO₂和ZnO溶胶灌充到PS模板微球的间隙内；最后通过煅烧去除PS而得多孔薄膜。采用SEM观察了薄膜的表面形貌，并用XRD对薄膜的性能进行了表征。结果表明，溶胶的浓度对薄膜形貌有着显著的影响。经煅烧后，TiO₂和ZnO薄膜分别为锐钛矿和六方纤锌矿结构。此外，对模板的组装及溶胶的灌注过程进行了分析。     

Matrix Groups Related to the Quaternion Group and Spherical Orbit Codes

We consider a finite matrix group with 3⁴· 2¹⁶ elements, which is a subgroup of the infinite group , where is the regular representation of the quaternion group and C is a matrix that transforms the regular representation Q to its cellwise-diagonal form. There is a number of ways to define the matrix C. Our aim is to make the group similar in a certain sense to a finite group. The eventual choice of an appropriate matrix C done heuristically. We study the structure of the group and use this group to construct spherical orbit codes on the unit Euclidean sphere in R⁸. These codes have code distance less than 1. One of them has 3²· 2⁸ = 2304 elements and its squared Euclidean code distance is 0.293. Communicated by: V. A. Zinoviev     

UH和UH_2分子的结构与势能函数

用相对论有效原子实势 (RECP)和密度泛函 (B3LYP SDD)方法研究了UH ,UH2 基态和低激发态的结构和势能函数 ,导出了分子的光谱数据 .结果表明 ,UH和UH2 的基电子状态分别为X4 Π和X3A2 ,离解能分别为 2 .886eV和5 .2 4 9eV ,UH2 具有C2v对称性 ,得到了UH和UH2 的几个不同的低激发态的结构与光谱数据 .应用多体项展式理论以及数字拟合方法 ,计算得到了UH分子和基态UH2 三原子分子的分析势能函数 ,该函数正确反映了UH和UH2分子的结构特征 ,可用于研究UHH的微观反应动力学 .     

湿法消解-氢化物发生-原子荧光光谱法测定土壤中的铅

应用AFS-230E型双道原子荧光光谱仪进行了氢化物发生-原子荧光法测定土壤中铅的研究.方法中采用硝酸做介质,将铁氰化钾直接加入硼氢化钠-氢氧化钠碱性溶液中,并对各种最佳分析条件进行了探讨和验证.铅的校准曲线在0-100μg/L浓度范围内呈线性,方法的检出限为0.14μg/L,相对标准偏差为2.1％,回收率为91.0％-95.0％.用标准物质进行对照,其测定值在给定的标准值范围之内.该方法操作简单、灵敏度高、高效,适合土壤样品中铅的测定.     

鸟苷发酵不同阶段发酵液紫外特征光谱的研究

研究了发酵不同阶段鸟苷发酵液的紫外吸收光谱,结果表明,鸟苷发酵不同阶段发酵液紫外吸收光谱会呈现相应的特征光谱。发酵前期除了275nm处的波峰外,在249nm又出现了一个新峰,并且随着发酵时间增加新峰逐渐升高成为主峰;发酵中期275nm处的波峰逐渐减弱并最后消失;发酵后期249nm处的波峰成为发酵液的特征波峰,并随时间的增加逐渐上升;发酵末期的显著特征为发酵液λmax的吸光值基本不变。鸟苷发酵不同阶段发酵液特征光谱研究为人们认识鸟苷发酵的动态过程提供了一种新的技术和途径,对于鸟苷发酵生产具有一定的指导意义。