银离子交换法制备光致变色玻璃的组成研究

本文应用差热分析、透射电镜、扫描电镜和X射线能谱等实验方法，研究了R2O-Al2O3-B2O3-SiO2系统玻璃组成对其分相、离子交换以及光色性能的影响规律；确定了能获得良好光色性能的最适宜玻璃组成范围。     

Improvement of Thermal Stability via Outer-Loop Ion Pair Interaction of Mutated T1 Lipase from Geobacillus zalihae Strain T1

Mutant D311E and K344R were constructed using site-directed mutagenesis to introduce an additional ion pair at the inter-loop and the intra-loop, respectively, to determine the effect of ion pairs on the stability of T1 lipase isolated from Geobacillus zalihae. A series of purification steps was applied, and the pure lipases of T1, D311E and K344R were obtained. The wild-type and mutant lipases were analyzed using circular dichroism. The T_m for T1 lipase, D311E lipase and K344R lipase were approximately 68.52 °C, 70.59 °C and 68.54 °C, respectively. Mutation at D311 increases the stability of T1 lipase and exhibited higher T_m as compared to the wild-type and K344R. Based on the above, D311E lipase was chosen for further study. D311E lipase was successfully crystallized using the sitting drop vapor diffusion method. The crystal was diffracted at 2.1 Å using an in-house X-ray beam and belonged to the monoclinic space group C2 with the unit cell parameters a = 117.32 Å, b = 81.16 Å and c = 100.14 Å. Structural analysis showed the existence of an additional ion pair around E311 in the structure of D311E. The additional ion pair in D311E may regulate the stability of this mutant lipase at high temperatures as predicted in silico and spectroscopically.     

Thermal and spectroscopic studies on flame-retardant cotton cellulose modified with THPC-urea-ADP and its transition metal complexes

Cotton cellulose has been treated with tetrakis(hydroxymethyl)phosphonium chloride (THPC), urea and small amounts of ammonium dihydrogen orthophosphate (ADP) to impart flame retardancy. Complexes of cell-THPC-urea-ADP with transition metals such as chromium, manganese, iron, cobalt, nickel, copper and zinc have been characterized by reflectance UV-visible spectra. The samples were subjected to differential thermal analysis and thermogravimetry from ambient temperature to 700°C in air to study their thermal behaviour. From the resulting data, various kinetic parameters for different stages of thermal degradation were obtained following the method of Broido. For the decomposition of cellulose and flame-retardant celluloses, the activation energy was found to increase from 242 to 322kJ mol^?1, the entropy of activation from 140 to 307 JK^?1 mol^?1 and the char yield from 2.5 to 31%. The free energy of activation for decomposition of cellulose and its derivatives was almost the same, viz. 148–162 kJ mol^?1, indicating that the basic steps in the decomposition of cellulose and its derivatives are the same. The IR spectra of the thermally degraded residues of cell-THPC-urea-ADP and its metal complexes indicate that dehydration takes place and a compound containing the carbonyl group is formed. The electron paramagnetic resonance signals indicate the formation of trapped and stable free radicals in the thermal degradation of cellulose and its derivatives.     

环境因子对木屑黄原酸酯合成的影响研究

对SCX药剂的合成进行了实验研究,确定了SCX的制备流程工艺;对合成的影响因素进行调整实验,确定合成效率最好的条件组合。优化实验包括:碱化木屑纤维的碱液浓度,黄化反应条件,CS2的用量,反应温度,反应时间等因素其对合成产品SCX的性能的影响程度。     

热循环对水泥基材料抗压强度的影响及机理研究

研究了硬化水泥基材料在20～180℃范围内热循环20次后强度的变化规律,经热循环试样强度较同龄期对比试样的强度有明显下降的结论.通过对水泥石和石英砂集料的线膨胀率的精确测定,对比两者线膨胀率的差异,找出热循环时导致水泥基材料内应力产生的原因,并解释硬化水泥基材料经热循环后强度性能降低的现象.     

抑制性谷氨酸门控氯离子通道的研究进展

作为半胱氨酸环配体门控离子通道中的一员,抑制性谷氨酸门控氯离子通道（IGIucl）的亚基及其装配具有多样性,从而导致其药理性质的不同。通道对某种化合物的选择性结合与通道中存在的一些关键位点的氨基酸残基有关。通道mRNA的转录后修饰作用是通道亚型及其功能多样化的原因。有关通道门控及离子选择机制的研究为新药及杀虫剂的开发和筛选奠定了基础。从药理性质、通道中影响药物结合特性的残基位点、通道基因的转录后修饰作用以及配体门控离子通道的门控机制等方面综述了IGluCl通道的研究情况。     

Aqueous polymerization of methyl methacrylate initiated by the redox system Ce(IV)—D-glucose. I: General features and kinetics

The polymerization of methyl methacrylate initiated by the ceric ammonium nitrate-D-glucose redox system has been studied in aqueous nitric acid under nitrogen in the temperature range 20-5 to 35°C. The initial rate of polymerization was determined gravimetrically whereas the initial rate of ceric ion disappearance was determined by titration of ceric ion. The relationships between conversion and D-glucose, Ce(IV), and monomer concentrations were determined. The dependence of the rates on D-glucose, Ce(IV), and monomer concentrations was evaluated. The effect of temperature was also examined.     

离子交换批量层析纯化重组类人胶原蛋白Ⅱ

对阳离子交换树脂CM52纯化类人胶原蛋白Ⅱ(Hum an-like Collagen B ioprote inⅡ,HCBⅡ)的合适条件进行了研究。通过实验,确定了批量层析的最佳操作条件,即在pH=4.0、NaC l 0.15 mol/L、进料质量浓度7 mg/mL、处理量17.26 mL/g进行吸附,吸附时间为60 m in,然后在pH=4.0、NaC l 0.30 mol/L下进行脱附。实验表明:采用批量层析吸附HCBⅡ后上柱洗脱,树脂CM52对HCBⅡ的吸附量可达到48.6 mg/g,回收率83.8%,最终纯化的HCBⅡ达电泳纯,相对分子质量为97k。     

优化燃烧器对裂解炉热效率的影响

衡量一台裂解炉优劣的标准,除了考虑其处理量与乙烯收率及裂解周期等因素以外,更重要的就是其能耗的高低。本文介绍了通过对燃烧器的改进,优化了裂解炉的各项参数,最终使裂解炉的热效率得到提高。     

Kinetic study of aqueous polymerization of methyl methacrylate initiated by Ce(IV)-maltose redox system

Polymerization of methyl methacrylate initiated by ceric ammonium nitrate-maltose has been investigated in aqueous nitric acid under nitrogen in the temperature range 20.5-35°C. The dependence of the initial rate of polymerization and the initial rate of ceric ion consumption on maltose, Ce(IV), and monomer concentrations has been determined. The reaction orders were found to depend on ceric ion concentration. At a moderately high Ce(IV) concentration (1 × 10^?3mol litre^?1) the orders were 1/2 and 3/2 with respect to maltose and monomer concentration, respectively, and independent of Ce(IV) concentration. But at a low Ce(IV) concentration (4 × 10^?4mol litre^?1) the orders with respect to monomer and Ce(IV) changed to 1 and 1/2, respectively. The effect of temperature was also examined. The average molecular weight, as determined by size-exclusion chromacography, was found to depend on maltose, Ce(IV), and monomer concentrations, as well as on temperature.     

液相电导法测定氯化氢脱析速率

介绍了采用液相电导法测定氯化氢脱析速率,从而测试聚氯乙烯树脂稳定性的方法,该方法能提供PVC树脂脱HCl的诱导期、降解速率及降解全过程的信息,与刚果红和老化白度法相比,能确切地反映树脂的热稳定性。     

石油化工加热设备用新型高效红外涂层

本文着重介绍了新型高效红外涂层在国内外的发展研究情况,对高效红外涂层在石油化工加热设备的节能机理、涂料的多功能性进行了阐述,并对高效红外涂层在石油化工加热设备中的应用前景进行了展望。     

氨合成塔触媒床层下沉高度初探

针对氨合成反应床层的下沉问题进行了分析,从堆积间隙和热变形二个重要的影响因素着手,建立模型并推导出了触媒床层下沉高度的计算通式,供床层结构设计参考。