First identification of isatin-β-thiosemicarbazones as novel inhibitors of New Delhi metallo-β-lactamase-1: Chemical synthesis,biological evaluation and molecular simulation

A series of isatin-β-thiosemicarbazone compounds were identified as novel inhibitors of New Delhi metallo-β-lactamase-1. The structure-activity relationship and possible binding mode were also established for further rational design of new inhibitors.     

萘由水到水-叔丁醇混合溶剂的迁移热力学函数

通过溶解度法研究了萘从水到水-叔丁醇(TBA)混合溶剂中的标准迁移热力学性质.结果表明, 标准迁移自由能随叔丁醇摩尔分数x(TBA)的增加表现出复杂的下降趋势.标准迁移熵和标准迁移焓呈现双峰变化.迁移熵和迁移焓的双峰变化, 表明系列H2O-TBA混合溶剂的微观结构经历了从相对的有序到无序到再有序、再无序、再有序的变化过程；H2O-TBA混合溶剂中除了在富水区存在着笼合物特殊结构外, 在x(TBA) 约为0.08处还存在着一相对有序的结构.     

利用TPD-MS、IR和XPS表征还原态Co-Mo/Al2O3

本文利用NO或/和CO吸附的TPD-MS方法, 结合IR和XPS对还原态的Co, Mo, Co-Mo/Al_2O_3催化剂进行了深入考索. 结果表明, 还原态的Co-Mo/Al_20_3表面上存在着两种吸附NO的Mo中心. 弱吸附NO(T_(max)为100 ℃)可被吸附的CO取代和强吸附NO(T_(max)为300 ℃)不能被CO取代. 同时存在三种吸附NO的CO中心, T_(max)分别为80 ℃、180 ℃和330 ℃. 前两者能吸附CO, 后者只吸附NO. IR结果对这些不同的Mo中心和Co中心的存在提供了进一步旁证. XPS结果表明提高还原温度, Mo/Al比保持恒定, 但Mo~(4+)浓度增加, 而Co/Al比却因部分Co进入Al_2O_3体相而降低。     

Synthetic studies of erythromycin derivatives: 6-O-methylation of (9S)-12,21-anhydro-9-dihydroerythromycin A derivatives

Synthetic studies on methylation of erythromycin derivatives were conducted. Methylation of 6 resulted in the formation of the C-3′ quaternary ammonium salts with a rate faster than 6-O-methylation. In dipolar aprotic solvent and under strong base conditions, 6-O-methylation, C-3′ quaternary ammonium salts formation and 2-C-methylation proceeded simultaneously to yield a mixture of three different products 7, 8 and 9. The quaternary ammonium salts were converted back to the corresponding tertiary amines 2, 10 and starting material 6 by employing sodium 4-pyridinethiolate as a N-demethylation reagent. The 6-O-methylation was eventually achieved in a good yield when a carbobenzyloxy (Cbz) group was utilized to protect the C-3′-dimethylamino group of 4. In this report, we will discuss the details of different reaction courses in the methylation of (9S)-12, 21-anhydro-9-dihydroerythromycin A derivatives.     

镧-锌杂多核配合物的合成和晶体结构

A new heteronuclear complex, [LaZnL₅(C₂H₅OH)(phen)]₂ (HL=α-methylacrylic acid, phen=1, 10-phen- anthroline), was synthesized and characterized by elemental analysis, infrared absorption spectra (IR) and single crystal X-ray diffraction analysis. The complex crystallizes in space group P1 with the cell dimensions a=12.614(3), b=14.485(4), c=12.148(2)?, α=109.68(2), β=115.65(1), γ=66.87(2)°. The complex mole- cule is a discrete tetranuclear molecule bridging by α-methylacrylate groups.     

阿司匹林合成过程的在线拉曼光谱研究

利用在线拉曼光谱的方法,跟踪阿司匹林合成反应过程的实验.直接观测到反应过程中体系的拉曼光谱随时间的变化,用小波变换的方法去除光谱的本底之后, 又利用多波长线性回归的方法对实验数据进行实时的处理,得到了实验中各组分的相对浓度随时间的变化.     

Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode

ＩｎｔｒｏｄｕｃｔｉｏｎＯｒｄｅｒｅｄｆｉｌｍｓｏｆｗａｔｅｒ ｉｎｓｏｌｕｂｌｅｓｕｒｆａｃｔａｎｔｓｃａｎｂｅｐｒｅｐａｒｅｄｂｙｃａｓｔｉｎｇｔｈｅｉｒｓｏｌｕｔｉｏｎｓｏｒｄｉｓｐｅｒｓｉｏｎｓｏｎｔｏａｓｏｌｉｄｓｕｐｐｏｒｔ .1Ｅｖａｐｏｒａｔｉｏｎｏｆｔｈｅｓｏｌｖｅｎｔａｆｔｅｒｃａｓｔｉｎｇｌｅａｖｅｓｔｈｉｎｆｉｌｍｓｅｌｆ ａｓｓｅｍｂｌｅｄｉｎｔｏｏｒｄｅｒｅｄｓｔａｃｋｏｆｂｉ ｌａｙｅｒ ,ｗｈｉｃｈｉｓｓｉｍｉｌａｒｔｏｂｉｏｌｏｇｉｃａｌｍｅｍｂｒａｎｅｆｏｒｍｅｄｂｙ…     

BEPCⅡ超导高频腔输入耦合器结构及特性研究

在高频加速系统中, 加速腔的输入耦合器是至关重要的部分之一, 其性能直接影响高频功率的耦合和加速腔的特性. 北京正负电子对撞机重大改造工程(BEPCⅡ)中的高频系统中, 超导高频加速腔采用的是同轴天线型功率输入耦合器, 这是首次在国内采用的500MHz频率的大功率耦合器. 本文中对这种超导腔耦合器的二次电子倍增效应情况、传输系数、热分布情况三方面的特性进行了研究. 研究结果表明, 耦合器在多个功率点存在二次电子倍增效应, 必需采取相应的措施来改善其对耦合器的不利影响; 通过对耦合器结构尺寸的优化使其在BEPCⅡ工作频率(499.8MHz)下能更有效地传输功率; 通过模拟计算, 得到了耦合器内外导体的热分布图象, 为校核和改进冷却设计和布局的合理性提供了重要的依据.     

A note on failure of the ladder approximation to QCD

In this Letter we show that the claim made in [V. Gogohia, Phys. Lett. B 611 (2005) 129] that the ladder approximation to QCD is internally inconsistent is incorrect. The incorrect conclusion in [V. Gogohia, Phys. Lett. B 611 (2005) 129] is based on the incorrect use of a QED-type Ward–Takahashi relation, which does not hold in the ladder approximation to QCD. We give a proof for this fact.     

Metal-free C3-alkoxycarbonylation of quinoxalin-2(1H)-ones with carbazates as ecofriendly ester sources

Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.