金银合金纳米粒子表面处理及其表面增强拉曼光谱研究

采用水合肼还原的方法制备了金银比例为1∶1的金银合金纳米粒子, 紫外可见吸收光谱显示合成的溶胶只有一个介于金和银之间的吸收峰, 证明了合金结构的形成. 通过氨基耦联方法将合金纳米粒子组装到硅片表面, 利用氯金酸与合金中银的反应对基底上合金纳米粒子表面进行了改性处理. 以吡啶为探针分子, 研究了表面处理前后基底的SERS效应的差别, 结果表明随着浸泡时间延长, 信号强度先逐渐增强后降低至不变, 这与合金纳米粒子表面结构的变化有关, 氯金酸与表面银的反应经历了两个过程, 即粒子表面形成小的孔洞(去合金过程)和AgCl(s)在粒子表面的沉积, 前者有利于SERS效应的提高, 而后者导致SERS效应快速衰减.     

The study on the preparation methods and the fluidity of large rare earth oxide particles

In this work large CeO₂ particles were prepared using H₂C₂O₄ and NH₄HCO₃ as precipitators. The effects of feeding mode and speed, stirring speed, aging time, precipitate and calcination temperature and precipitation method on physicochemical properties of CeO₂ were studied when the precipitator was H₂C₂O₄. By the NH₄HCO₃ precipitation method, the effects of adding inoculating crystals and additives on particle size, loose density and fluidity of CeO₂ were investigated. Under optimized conditions, large CeO₂ particles with high loose density and good fluidity of can be prepared by either H₂C₂O₄ or NH₄HCO₃ precipitation method. SEM also investigates the morphology of the particles prepared by both methods. The results show that physicochemical properties of CeO₂ particles prepared by the NH₄HCO₃ precipitation method are not as good as those of CeO₂ particles prepared by the H₂C₂O₄ precipitation method. However, both methods are suitable for industrial production due to their simple processes, low equipment investment and ease for industrial development. Our results show that large rare earth particle can be prepared by the optimized conventional methods. This study provided a useful method to prepare of large rare earth particles.     

Imaging glycosylation

The glycosylation state of individual antibodies was imaged using an atomic force microscope with a probe modified with lectins and an image acquisition system that permits simultaneous acquisition of sample topography data along with a map of lectin binding sites.     

Integrating sensitive quantification of hepatic metabolic functions by capillary electrophoresis with laser-induced fluorescence detection

We report the establishment of capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection as a common analytical platform for sensitive quantification of both phase I and II metabolism in various hepatic in vitro models.     

Two new coumarins from Herpetospermum caudigerum

The ethyl acetate extract from the seeds of Herpetospermum caudigerum was found to show protective effects on carbon tetrachloride (CCl(4)) and thioacetamide (TAA)-induced acute hepatic injuries in mice. From the ethyl acetate extract, two new coumarins, herpetolide A (1) and herpetolide B (2), along with four known compounds, herpetone (3), dehydrodiconiferyl alcohol (4), 2,4-dihydroxypyrimidine (5) and stigmasterol (6) were isolated. The structures of the new coumarins were elucidated on the basis of chemical and physicochemical evidences. Herpetone exhibited protective effects on CCl(4)-induced hepatocyte injury.     

Nortriterpenoids from Schisandra wilsoniana

Three new highly oxygenated nortriterpenoids, wilsonianadilactones A–C ( 1 – 3 ), together with twelve known ones, i.e., 4 – 15 , were isolated from the leaves and stems of Schisandra wilsoniana. Their structures were established by means of extensive analysis of spectroscopic data, and compound 1 was further confirmed by X‐ray crystallographic diffraction. Compounds 1 – 3 showed weak anti‐HIV‐1 activity with EC₅₀ values of 23.5, 55.5, and 66.4 μg/ml, respectively.     

Visible light-driven electron transfer and hydrogen generation catalyzed by bioinspired [2Fe2S] complexes

Complexes [{(mu-SCH2)2NCH2C6H5}{Fe(CO)2L(1)}{Fe(CO)2L(2)}] (L(1) = CO, L(2) = P(Pyr) 3, 2; L(1) = L(2) = P(Pyr)3, 3) were prepared, which have the lowest reduction potentials for the mono- and double-CO-displaced diiron complexes reported so far. Hydrogen evolution, driven by visible light, was successfully observed for a three-component system, consisting of a ruthenium polypyridine complex, the biomimetic model complex 2 or 3, and ascorbic acid as both electron and proton donor in CH3CN/H2O. The electron transfer from photogenerated Ru(bpy)3(+) to 2 or 3 was detected by laser flash photolysis. Under optimal conditions, the total turnover number for hydrogen evolution was 4.3 based on 2 and 86 based on Ru(bpy)3(2+) in a three-hour photolysis.     

Synthesis and anti-HIV-1 activity of S-dihydro(alkyloxy)benzyloxypyrimidine derivatives

Several 2-heteroaryl-, 2-heteroarylcarbonylmethyl-, 2-arylcarbonylmethyl, and 2-arylethyl derivatives of S-dihydro(alkyloxy)benzyloxypyrimidines have been synthesized and the anti-HIV activities of these compounds were tested in C8166 cell and against RT enzyme. It was found that some of these compounds showed good activity against HIV-1 (EC ₅₀ = 0.014–0.8 μM) with low toxicity (CC ₅₀ value of 222–564 μM) and high selectivity (SI value of 278–37743). The structure-activity relationships (SAR) of these compounds have also been discussed. First two authors contributed equally to this work Correspondence: Yan-Ping He, Key Laboratory of Medicinal Chemistry for Natural Resource Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091, People’s Republic of China; Yong-Tang Zheng, Laboratory of Molecular Immunopharmacology, Key Laboratory of Animal Models and Human Disease Mechanisms, Chinese Academy of Sciences, Kunming Institute of Zoology, Kunming, Yunnan 650223, People’s Republic of China.     

苯酚在Ti/PbO2电极上的电氧化反应

利用线性伏安法和恒电流电解法研究了苯酚在Ti／PbO2电极上的电催化氧化反应,通过电氧化过程中反应物和中间物的高效液相色谱测定,研究了苯酚在Ti／PbO2电极上电催化氧化的反应机理．实验发现,Ti／PbO2电极对水溶液中苯酚的电氧化具有显著的催化作用,25℃时,对初始浓度为2mmol／L的苯酚水溶液,恒定电流密度为50mA／cm2,电解3h,苯酚转化率为98．02％,有机碳去除率为54．36％．苯酚在Ti／PbO2电极上电催化氧化要经过对苯二酚或邻苯二酚、对苯醌、反丁烯二酸和草酸,最终变成二氧化碳和水的历程．第一步反应苯酚转化的主产物是对苯二酚．对苯二酚转化为苯醌和苯醌转化为反丁烯二酸的反应为慢反应,反丁烯二酸转化为草酸的反应为快反应．     

环境中铬形态分析研究进展

对近10年来国内外在环境中铬形态方面的分析研究进展作了综述,内容包括样品预处理、分离富集方法和样品检测方法(引述文献61篇).