Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115

Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na⁺, Ca²⁺, Mg²⁺, and Mn²⁺. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties.     

Ring‐opening polymerization of lactones initiated by diphenylzinc–coinitiator systems

Diphenylzinc, alone or in combination with water and butanone as coinitiators, was used as a polymerization initiator system for a variety of lactones at varying temperatures. The resulting data indicate that the course of the polymerization is greatly influenced by the lactone structure, as well as by the molar ratio of coinitiator to diphenylzinc. When used alone, diphenylzinc exhibited high activity as an initiator in δ‐valerolactone polymerizations, although it was less efficient when used in the β‐butyrolactone and the β‐propiolactone polymerizations. Activity in the polymerization of β‐lactones was increased by adding small amounts of butanone or water. It was also observed that the diphenylzinc–butanone combination was more effective than the diphenylzinc–water mixture in the polymerizations of β‐butyrolactone and β‐propiolactone. Copyright © 2003 Society of Chemical Industry     

N-油酰基肌氨酸钠对除盐水缓蚀性能的探讨

对N-油酰基肌氨酸钠单体的缓蚀性能以及与常用除盐水缓蚀剂的协同作用作了探讨,发现在一定浓度下,单体对经过加氨调节后的高温除盐水(氨后除盐水)有良好的缓蚀作用,且与大多数除盐水缓蚀剂有良好的协同效应。在此基础上研制了一种复合药剂,并对其缓蚀、阻蚀性能作了研究。动电位极化曲线扫描图谱表明,该复合药剂属于抑制阳极腐蚀的阳极型缓蚀剂,其适用的水质条件为[Cl~-+SO_4~(2-)]不超过50 mg／L,pH不低于8.0；与阻垢剂复配,可以适用于含Ca~(2+)不超过45 mg／L的水质条件。     

离子交换法合成三氨基胍叠氮酸盐

三氨基胍叠氮酸（ＴＡＺ）分子中的含氮量高达８５．７％，燃烧分解时不仅－Ｎ３可释放３６７ｋＪ／ｍｏｌ的键能，而且放出大量的氮气，是一个提高比冲，降低燃烧温度的理想的推进剂两组分之一。     

Deciphering the Binding Interactions between Acinetobacter baumannii ACP and β-ketoacyl ACP Synthase III to Improve Antibiotic Targeting Using NMR Spectroscopy

Fatty acid synthesis is essential for bacterial viability. Thus, fatty acid synthases (FASs) represent effective targets for antibiotics. Nevertheless, multidrug-resistant bacteria, including the human opportunistic bacteria, Acinetobacter baumannii, are emerging threats. Meanwhile, the FAS pathway of A. baumannii is relatively unexplored. Considering that acyl carrier protein (ACP) has an important role in the delivery of fatty acyl intermediates to other FAS enzymes, we elucidated the solution structure of A. baumannii ACP (AbACP) and, using NMR spectroscopy, investigated its interactions with β-ketoacyl ACP synthase III (AbKAS III), which initiates fatty acid elongation. The results show that AbACP comprises four helices, while Ca²⁺ reduces the electrostatic repulsion between acid residues, and the unconserved F47 plays a key role in thermal stability. Moreover, AbACP exhibits flexibility near the hydrophobic cavity entrance from D59 to T65, as well as in the α₁α₂ loop region. Further, F29 and A69 participate in slow exchanges, which may be related to shuttling of the growing acyl chain. Additionally, electrostatic interactions occur between the α₂ and α₃-helix of ACP and AbKAS III, while the hydrophobic interactions through the ACP α₂-helix are seemingly important. Our study provides insights for development of potent antibiotics capable of inhibiting A. baumannii FAS protein–protein interactions.     

Propagation of the Chain Explosive‐Decomposition Reaction in Silver Azide Crystals

The velocity of the chain explosivedecomposition reaction in silver azide whiskes has been measured (1500 m/sec). The measured velocity is identified as the propagation velocity of the diffusion front of holes generated in the course of explosive decomposition.     

对硝基叠氮苄的合成

有机叠氮化合物在合成反应中有着重要意义。对硝基溴化苄和叠氮化钠在一定条件下反应，得到对硝基叠氮苄。     

海洋工程应用水下涂装防污涂料的研究

将叠氮基团接枝到环氧树脂上以提高环氧树脂的湿态附着强度,然后将其与环氧树脂618按不同比例复配制备成水下涂装防污涂料,并对涂料的附着强度、铜离子渗出率及海洋防污性能进行研究。研究表明,随着叠氮化环氧树脂用量的增加,水下防污涂层的附着强度先升高后降低;铜离子渗透出率测定和实海浸泡表明该水下涂装防污涂料具有一定的防污性能。     

POSS-based hybrid thermosets via photoinduced copper-catalyzed azide–alkyne cycloaddition click chemistry

An efficient approach for the preparation of inorganic/organic hybrid thermosets via photoinduced copper-catalyzed azide–alkyne cycloaddition click chemistry is established. Highly cross-linked thermoset polymers have been practically obtained by this technique using multifunctional compounds, tri-alkyne (1,1,1-tris[4-(2-propynyloxy) phenyl]-ethane) with octakis-azido-POSS or tri-azide (3,3′-((2-((3-azido-2-hydroxypropoxy)methyl)-2-ethylpropane-1,3-diyl)bis(oxy))bis(1-azidopropan-2-ol)) in the presence of Cu(II)Br₂/N,N,N′,N″,N?-pentamethyldiethylenetriamine/2-dimethoxy-2-phenyl acetophenone. The homogeneously distributed POSS nanoparticles are clearly detected in the TEM micrographs; whereas the TGA analysis shows that the obtained hybrid thermosets are thermally stable up to 360 °C and begin to lose weight at higher temperatures with a char yield of 23–50% at 800 °C.     

5-芳亚甲基-N-(4-羧基苯基)罗丹宁衍生物的微波辅助合成及分子模拟研究

以对氨基苯甲酸为原料,采用简易方法合成N-(4-羧基苯基)罗丹宁,并在醋酸和醋酸钠体系中与芳香醛化合物经回流反应或微波辐射合成(Knoevenagel缩合)得到系列标题化合物,并用Sybyl-X 2.0程序研究了标题化合物与烯酰基载体蛋白(ACP)还原酶的分子对接情况。