ICP-AES法同时测定TiNi形状记忆合金中杂质Co、Cu、Cr、Fe、Nb

研究建立了ICP—AES同时测定TiNi形状记忆合金中Co、Cu、Cr、Fe、Nb5元素的方法。进行了必要的条件试验，选择了分析线及其他仪器工作参数；考察了方法检出限、H2SO4酸度及基体钛、镍对测定的影响、工作曲线线性。进行了准确度和精密度试验，各元素的加标回收率为Co98．4％。99．6％、Cu98．0％～103％、Cr98.9％～99．6％、Fe94．6％～95．8％、Nb99．8％。102％。5种元素的相对标准偏差范围为4．2％-10％。     

成都经济生态区大气降尘中镉赋存形态的研究

采用Tessier连续提取法对成都经济生态区不同区域的24个大气降尘样中镉的赋存形态进行了研究。研究结果表明,大气降尘中的镉主要以残留态形态存在;各形态镉在总镉中所占百分比含量由大到小排列顺序依次是:残留态,碳酸盐结合态,交换态,铁锰结合态,有机结合态;交换态镉、碳酸盐结合态镉这两种具有较高生物有效性的形态镉在总镉中所占的平均百分比含量分别是6.420%和8.917%;铁锰氧化物结合态、有机结合态、残留态镉这三种形态镉生物有效性很低,分别在总镉中所占的平均百分比含量分别是3.419%、2.365%和78.907%。通过分析可得出,汽油和煤的燃烧以及工厂排放镉能加大城市大气降尘的镉污染。     

四川地区宫颈癌组织HPV18和HPV45 E6基因突变分析

采用聚合酶链反应技术对四川地区2003~2004年收集的60例宫颈癌患者的癌组织DNA进行人乳头瘤病毒(HPV) E6基因扩增, 获得HPV18和45型E6基因. 序列分析发现, 18型三例E6基因有同样的两处同义突变; 45型两例E6基因发生突变, 一例有两处碱基突变, 另一例发生六处碱基突变, 其中两处涉及氨基酸变化, 均位于E6抗原决定簇区. HPV45型E6基因中134位c→t, 157位c→t, 259位g→t和341位t→c的碱基点突变未见报道. 另外， 该地区HPV18和45型突变株之间存在碱基互变,  它们之间的最小差异比野生型HPV18和HPV45之间的差异小4.05%, 该数值比在非洲发现的突变株的要小很多, 该结果支持HPV18和HPV45可能起源于非洲的观点.     

以含铬类水滑石型层状化合物为模板制备硫化物半导体纳米晶

采用类水滑石型混合金属氢氧化物(CdCr-LDH和ZnCdCr-LDH)为前驱体, 通过气-固反应方法, 制备了根植于层状氢氧化物层板中的硫化镉纳米晶和硫化镉/硫化锌复合纳米晶, 通过改变前驱体(CdCr-LDH)中镉和铬的摩尔比可以调控硫化镉纳米晶的粒径.     

Interaction of human immunodeficiency virus (HIV) glycans with lectins of the human immune system

Approximately half of the molecular mass of gp120, the receptor-binding envelope protein of human immunodeficiency virus (HIV), consists of N-linked glycans. Nearly half of these glycans are of the high mannose type. These high mannose glycans furnish a rich forest of mannose residues on the virus surface making HIV a prime target for interaction with mannose-specific lectins of the immune system. This review focuses on the known interactions between gp120 and immune system lectins some of which HIV appears to exploit. The effect of variation in glycosylation of gp120, especially with respect to clades of HIV, on binding of immune system lectins is highlighted.     

Triterpenoid Saponins from Schefflera arboricola

Four new triterpenoid saponins, named scheffarboside A – D ( 1 – 4 ), along with five known saponins were isolated from the stems of Schefflera arboricola. The structures of the four new saponins were determined as 3‐O‐(O‐β‐glucuronopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid ( 1 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid ( 2 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)hederagenin ( 3 ), 3‐O‐(O‐α‐arabinopyranosyl‐(1 → 4)‐O‐α‐arabinopyranosyl‐(1 → 3)‐O‐α‐rhamnopyranosyl‐(1 → 2)‐α‐arabinopyranosyl)oleanolic acid O‐α‐rhamnopyranosyl‐(1 → 4)‐O‐β‐glucopyranosyl‐(1 → 6)‐β‐glucopyranosylester ( 4 ), respectively, on the basis of spectroscopic and chemical degradation methods.     

A New 18(13 → 12β)‐abeo‐Lanostadiene Triterpenoid from Ganoderma fornicatum

A new triterpenoid, fornicatin C (= (3β)‐3‐hydroxy‐18(13 → 12β)‐abeo‐lanosta‐13(17),24‐dien‐18‐oic acid; 1 ), was isolated from the fruiting bodies of Ganoderma fornicatum, together with the known compounds fornicatin A ( 2 ) and fornicatin B ( 3 ), among other constituents. The structure of 1 was elucidated by means of spectroscopic techniques, and those of 2 and 3 were identified by comparing their spectroscopic data with those reported in the literature.     

Multilayer films of carbon nanotubes and redox polymer on screen-printed carbon electrodes for electrocatalysis of ascorbic acid

Multilayer films containing multiwall carbon nanotubes and redox polymer were successfully fabricated on a screen-printed carbon electrode using layer-by-layer (LBL) assembled method. UV-vis spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and electrochemical method were used to characterize the assembled multilayer films. The multilayer films modified electrodes exhibited good electrocatalytic activity towards the oxidation of ascorbic acid (AA). Compared with the bare electrode, the oxidation peak potential negatively shifted about 350 mV (versus Ag/AgCl). Furthermore, the modified screen-printed carbon electrodes (SPCEs) could be used for the determination of ascorbic acid in real samples.     

Extended application of a chiral stationary phase based on (+)-(1 8-crown-6)-2,3,11,12-tetracarboxylic acid to the resolution of N-(substituted benzoyl)-alpha-amino acid amides

A chiral stationary phase (CSP 1) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of N-(substituted benzoyl)-alpha-amino acid amides and esters. N-(Substituted benzoyl)-alpha-amino acid amides were well resolved using a mixture of acetic acid-triethylamine-acetonitrile (0.01:0.05:100, v/v/v) as an optimum mobile phase while N-(substituted benzoyl)-alpha-amino acid esters were not resolved at all. In contrast, both N-(substituted benzoyl)-alpha-amino acid amides and esters were not resolved at all or resolved very poorly on another CSP (CSP 2), which lacks the two N-H hydrogens of the amide tethers of CSP 1. Among the substituents on the benzoyl group of analytes, the nitro group was the best for good resolution of analytes on CSP 1. From these results, the two N-H hydrogens of the amide tethers of CSP 1, the carbonyl oxygen of the amide group of analytes, and the nitro group on the benzoyl group of analytes were concluded to play significant roles in chiral recognition. In addition, various N-(3,5-dinitrobenzoyl)leucine amides with different lengths of N-alkylamide chains were resolved on CSP 1 and N-(3,5-dinitrobenzoyl) leucine N-propylamide was found to show the best chiral recognition in terms of the separation (alpha = 1.30) and the resolution factor (Rs= 3.17).     

NC3O分子体系的异构化及其结构和性能的理论研究

采用 DFT, QCISD 及 CCSD(T)方法, 对 NC3O 分子体系的异构化进行了系统的研究, 得到了5个稳定的异构体, 其中包括4个链状异构体和1个带有支链的平面结构异构体. 这5个稳定异构体都具有较高的动力学和热力学稳定性.