C3N4的高温高压同步辐射研究

利用激光加热金刚石对顶砧技术在高温高压条件下合成了纯beta相和立方相C₃N₄beta相C₃N₄所属对称群为P63/M (176).对石墨相与beta相C₃N₄的X射线衍射结果进行了精确分析, 得到优化晶胞参数.原位高压同步辐射X射线衍射分析表明, 在6GPa时由beta相到立方相C₃N₄的相转变已经发生, 之后两相共存直到19GPa时相变结束得到纯立方相C₃N₄.     

Structure of Coordination Polymer, 〔Zn(bipy)(H_2O)_3SO_4〕·2H_2O (bipy=4,4'-bipyridine)

1　INTRODUCTION4,4' bipyridine( bipy) is a good candidate for building open framework struc ture because of their rodlike rigidity and length.Framework structures formed bytransition metalsbridged by bipy vary with metaland anion.The structures of Zn bipy system include interpenetrating square grid sheets〔 Zn( bipy) 2 ( H2 O) 2 〕Si F6〔1〕,two dimensionallayer〔 Zn( bipy) ( H2 O) 4 〕( NO3) 2 · bipy〔2〕,〔 Zn( bipy) ( H2 O) 4 〕 ( NO3) 2 · 2 bipy· 3 H2 O〔2〕 and〔 Zn( bipy)…     

利用有机改性的类水滑石缓释阿维菌素

采用蒸发溶剂促进插层(evaporating solvent enhanced intercalation)的方法把农药阿维菌素(Avermectin, AVM)插层到十二烷基硫酸钠(SDS)改性的类水滑石(Hydrotalcite-like compound, HTlc)层间，合成了AVM-SDS-HTlc纳米杂化物。研究发现其能够很好的控制阿维菌素的释放，表明AVM-SDS-HTlc纳米杂化物是一种很有潜力的农药控释剂型。AVM-SDS-HTlc纳米杂化物的释放受pH、温度和电解质的影响，酸性介质、较高温度以及有电解质存在会提高其缓释速率。释放过程符合准一级释放动力学，释放的活化能为279 kJ/mol。     

Synthesis and characteristic of double hydrophilic block copolymer with amine pendant chains

Novel double hydrophilic block copolymers with amine pendant chains were synthesized by polymerization of 4-vinyl benzylamine hydrochloric salt using 4,4′-azo-bis[4-cyanopentanoate poly（ethylene glycol） ester] as macroazoinitiator. The structures of the copolymers were characterized by ^1H NMR, FTIR spectra and acid-base titration, GPC-MALS techniques.     

Structural phase transition,strength,and texture in vanadium at high pressure under nonhydrostatic compression

The structural phase transition, strength, and texture of vanadium have been studied under nonhydrostatic compression up to 70 GPa using an angle-dispersive radial x-ray diffraction technique in a 2-fold paranomic diamond anvil cell and up to 38 GPa using an angle-dispersive x-ray diffraction technique in a modified Mao–Bell diamond anvil cell at room temperature. We have confirmed a phase transition from body-centered cubic structure to rhombohedral structure at 27–32 GPa under nonhydrostatic compression. The radial x-ray diffraction data yields a bulk modulus K_0= 141(5) GPa and its pressure derivative K_0′= 5.4(7) for the bcc phase and K_0= 154(13) GPa with K_0′= 3.8(3) for the rhombohedral phase at ψ = 54.7°. The nonhydrostatic x-ray diffraction data of both bcc and rhombohedral phases yields a bulk modulus K_0= 188(5) GPa with K_0′= 2.1(3). Combined with the independent constraints on the high-pressure shear modulus, it is found that the vanadium sample can support a differential stress of ～1.6 GPa when it starts to yield with plastic deformation at ～36 GPa. A maximum differential stress as high as ～ 1.7 GPa can be supported by vanadium at the pressure of ～ 47 GPa.In addition, we have investigated the texture up to 70 GPa using the software package MAUD. It is convinced that the bodycentered cubic to rhombohedral phase transition and plastic deformation due to stress under high pressures are responsible for the development of texture.     

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

采用水溶液均聚合方法,制备了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AMC14AB)的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P(AMC14AB)在水溶液中的胶束化行为与表面吸附现象. 在水溶液中,均聚物P(AMC14AB)呈现单分子链胶束的聚集形态,具有零临界胶束浓度,从开始加入P(AMC14AB)起,水溶液中随即产生单分子链胶束,不存在Krafft温度. P(AMC14AB)在溶液表面也发生表面吸附,使水的表面张力下降,即P(AMC14AB)也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达饱和时,表面张力～浓度曲线上出现突变点,该点定义为饱和的表面吸附浓度,而不应该再称为临界胶束浓度. P(AMC14AB)单分子链胶束溶液对疏水有机物(甲苯)的增溶情况,明显不同于普通小分子表面活性剂十六烷基溴化铵(CTAB)的多分子胶束溶液,甲苯增溶量～P(AMC14AB)浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液.     

神经介素B受体与拮抗剂、激动剂的分子模拟研究

大鼠神经介素B受体(rat neuromedin B receptor, rNMBR)属于G蛋白偶联受体(G-protein coupled receptor, GPCR) A家族的成员. GPCR的结构特征和在信号传导中的重要作用决定了其可以作为很好的药物靶标. 关于rNMBR与内源性激动剂神经介素B (neuromedin B, NMB)以及与非肽类拮抗剂pd168368作用机制的研究对于合理设计受体药物分子有重要的指导意义. 在这一研究中, 我们使用同源模建, 构建受体的三维结构, 进行分子对接和分子动力学的计算. 基于受体三维结构, 通过10 ns的空载受体、激动剂-受体、拮抗剂-受体的分子动力学模拟, 探讨受体与激动剂与拮抗剂的作用机制. 研究表明rNMB-R中跨膜(transmembrane, TM)螺旋3, 5, 6, 7参与配体的结合. NMB与受体的结合, 使受体转变为活性构象, 而受体同拮抗剂pd168368恰好相反.     

Capillary electrophoresis-laser induced fluorescence analysis of endogenous damage in mitochondrial and genomic DNA

Reactive oxygen molecules are formed in vivo as by-products of normal aerobic metabolism. All organisms dependent on oxygen are inevitably exposed to these species so that DNA damage can occur in both genomic and mitochondrial DNA (mtDNA). In order to determine endogenous DNA damage we have developed an analytical method that involves the isolation and hydrolysis of genomic DNA or mtDNA, the labeling of modified and unmodified nucleotides and micellar electrokinetic chromatography with laser-induced fluorescence detection. With this method we have found etheno-adenine, thymine glycol, uracil, hypoxanthine, and 5-methylcytosine. These were identified by the addition of internal standards to the genomic or mtDNA. There are a large number of other signals in the electropherograms of mtDNA that we have never found in genomic DNA analysis because they are at lower concentration in the genome. In the DNA of untreated patients with chronic lymphocytic leukemia (CLL), uracil and high levels of etheno-adenine were found, which can be explained by antioxidant enzyme alterations and oxidative stress in the CLL lymphocytes.