半对偶化对和半对偶化双模的一个刻画（英文）

在这篇文章中,我们引入并研究了Artin-代数上的半对偶化模对,它推广了由Miyashita定义的倾斜模对的概念.一方面,我们把有关半对偶化模的相关结论推广到了半对偶化模对上。另一方面在任意结合环R上,我们给出了半对偶化模的一个刻画.     

Fullerene‐Catalyzed Reduction of Azo Derivatives in Water under UV Irradiation

Metal‐free fullerene (C₆₀) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH₄. Use of NaBH₄ by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C₆₀ catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N?N bond. UV irradiation increases the ability of C₆₀ to interact with electron‐donor moieties in azo dyes.     

A new near-infrared fluorescent chemodosimeter for discrimination of sulfide from disulfide

Research on Chemical Intermediates - A new near-infrared fluorescent “turn-on” chemodosimeter (probe 1) based on dicyanomethylene-4H-chromene fluorophore for sulfide was developed....     

Z-164D溶液对铝土矿强度的影响及其作用机理

以Z-164D为助磨剂，对广西田阳铝土矿进行了邦德球磨功指数试验和单轴抗压强度试验.结果表明:铝土矿经水和Z-164D溶液浸泡后，邦德球磨功指数分别下降了105%和379%，单轴抗压强度分别下降了2684%和4279%.红外光谱分析及X射线能谱微区元素分析表明，Z-164D只能在铝土矿表面发生物理和化学吸附，并不能够渗入铝土矿内部.建立了Z-164D溶液对铝土矿强度影响的作用机理模型，水分子与Z-164D相互促进，共同导致铝土矿缺陷程度增加、强度降低.     

Physical,hydrochemical and isotopic characteristics of springs in Beijing,China, compared to historical properties

A physical, hydrochemical and isotopic evaluation of springs in Beijing was conducted in 2009 to reveal apparent changes in the properties of those springs. The results showed that most of the 2nd class springs and more than 50 % of the 1st class springs recorded in the early 1980s were depleted, while the discharges of existing springs have also decreased sharply. In addition, the majority of springs were of the HCO₃–Ca–Mg type and good water quality, with the quality indices changing slightly compared to those recorded 30 years ago. The abundances of ²H, ¹⁸O, and ³H in the springs indicated that most of the springs were of meteoric origin with a relatively close connection to modern atmospheric precipitation. As a result, the springs have a relatively strong renewability within a shallow circulation.     

Activity Essential Residue Analysis of Taxoid 10β-O-Acetyl Transferase for Enzymatic Synthesis of Baccatin

Taxoid 10β-O-acetyl transferase (DBAT) is a key enzyme in the biosynthesis of the famous anticancer drug paclitaxel, which catalyses the formation of baccatin III from 10-deacetylbaccatin III (10-DAB). However, the activity essential residues of the enzyme are still unknown, and the acylation mechanism from its natural substrate 10-deacetylbaccatin III and acetyl CoA to baccatin III remains unclear. In this study, the homology modelling, molecular docking, site-directed mutagenesis, and kinetic parameter determination of the enzyme were carried out. The results showed that the enzyme mutant DBAT^H162A resulted in complete loss of enzymatic activity, suggesting that the residue histidine at 162 was essential to DBAT activity. Residues D166 and R363 which were located in the pocket of the enzyme by homology modelling and molecular docking were also important for DBAT activity through the site-directed mutations. Furthermore, four amino acid residues including S31 and D34 from motif SXXD, D372 and G376 from motif DFGWG also played important roles on acylation. This was the first report of the elucidation of the activity essential residues of DBAT, making it possible for the further structural-based re-design of the enzyme for efficient biotransformation of baccatin III and paclitaxel.     

On the non-symmetric planar aligned NLC cell

The planar aligned nematic liquid crystal cell with different anchoring for the two substrates (i.e. a non-symmetric NLC cell) is investigated by an analytical method. We deduce the basic equations and the boundary conditions of the tilt angle θ of the LC director. Expressions for threshold and saturation magnetic field are obtained, and numerical results of these two quantities with variation in anchoring parameters of the two substrates are given. A symmetry breaking parameter Δ is introduced and the relations between Δ and applied field, as well as the two sets of anchoring parameters are discussed in detail. A feasible experimental plan for measurement of anchoring strengths of a series of different substrates is proposed.