气-气复合型高选择性氢气敏感元件

根据半导体气敏元件电路工作原理,设计了一种新型的气－ 气复合型的半导体Ｈ２ 敏感元件,推导出了其灵敏度、选择性及热稳定性的关系式,指出了构成高选择性及好的热稳定性的复合气敏元件需满足的条件,并在实验中得到验证。     

Production,Purification, and Characterization of Thermoanaerobacterium thermosaccharolyticum Glucoamylase

Glucoamylase from Thermoanaerobacterium thermosaccharolyticum ATCC 7956 (DSM 571) was produced in extracellular form. It was purified to homogeneity by two separate methods, one with two chromatographic steps and the other with three. This glucoamylase is closely related to glucoamylases from Clostridium sp. G0005 and T. thermosaccharolyticum DSM 572. Activities and K_M values with maltose substrate are less than one‐tenth and about fourfold, respectively, those of Aspergillus niger glucoamylase. T. thermosaccharolyticum glucoamylase is about twenty times as thermostable as A. niger glucoamylase and its optimal pH is somewhat higher at 4.9; however, it is produced in much lower activities. Sorbitol strongly stabilizes A. niger glucoamylase.     

食品加工业中菠萝蛋白酶的热稳定性

运用动力学的方法研究了菠萝蛋白酶的热稳定性，发现某些多羟基、多羟基化合物能明星延长菠萝蛋白酶在较高温度下的半寿期。这些物质无毒无害，能安全有效的提高食品加工业中菠萝蛋白酶的贮藏期和使用期。     

两种不同类型热作模具钢的使用性能研究

对马氏体型热作模具钢SDH3和奥氏体型热作模具钢SDHA作了对比分析,研究了两者在力学性能、热稳定性和热疲劳性能方面的区别。结果表明:SDH3钢具备良好的热稳定性和热疲劳性能,可以满足通用热作模具钢的使用要求;SDHA钢经固溶和时效处理后,在750℃×20h长时间保温过程中,硬度保持稳定,表明可以用于制作工作温度在700℃以上的热作模具。     

炭材料用基体前驱体沥青的改性研究

首次以二乙烯基苯为交联剂,在酸性催化剂的作用下对煤沥青进行了改性研究,同时对改性后的煤沥青进行显微结构和耐热性分析。研究结果表明：改性后的煤沥青不仅出现大量的中间相小球,而且耐热性优良,可作为炭材料优质的基体前驱体。     

Improvement of Aspergillus niger Glucoamylase Thermostability by Directed Evolution

Directed evolution was used to improve the thermostability of Aspergillus niger glucoamylase (GA) expressed in Saccharomyces cerevisiae. A starch‐plate assay developed to screen GA mutants for thermostability gave results consistent with those of irreversible thermoinactivation kinetic analysis. Several thermostable multiply‐mutated GAs were isolated and characterized by DNA sequencing and kinetic analysis. Three new GA mutations, T62A, T290A and H391Y, have been identified that encode GAs that are more thermostable than wild‐type GA, and that improve thermostability cumulatively. These individual mutations were combined with the previously constructed thermostable site‐directed mutations D20C/A27C (forming a disulfide bond), S30P, and G137A to create a multiply‐mutated GA designated THS8. THS8 GA is substantially more thermostable than wild‐type GA at 80°C, with a 5.1 kJ/mol increase in the free energy of thermoinactivation, making it the most thermostable Aspergillus niger GA mutant characterized to date. THS8 GA and the singly‐mutated GAs have specific activities and catalytic efficiencies (k_cat/K_m) similar to those of wild‐type GA.     

核燃料热行为的热分析研究

本文介绍了下列几种实验研究:用热分析法研究制备快堆低密度燃料芯块的六种造孔剂的热分解过程;U_3Si_2在氮气、氩气气氛中的热稳定性。     

定位诱变脊髓灰质炎疫苗株VP1壳蛋白提高疫苗的热稳定性

本文首次在脊髓灰质炎疫苗株VP1壳蛋白上用计算机探索了氨基酸取代对热稳定性的影响。Menendez-Arias等研究发现,使蛋白质α-螺旋区内刚性(螺旋趋势)增加,亲水性减少,能适应更热的环境。而少数几个氨基酸的取代则能实现这种改变。本文运用本室建立的蛋白质二级结构预测的计算机程序在VP1壳蛋白上寻找α-螺旋区,选择出亲水概率大的并与中和抗原决定簇区无关的α-螺旋区作为氨基酸取代的区域。在这些区域上进行了有效的几个氨基酸取代后,均能使α-螺旋趋势增加,亲水性减少,而取代部位两侧氨基酸残基构型基本上没有发生变化,这与文献报道的结果是一致的。这项工作可为将来利用基因工程方法,设计、寻找工程蛋白提高脊髓灰质炎疫苗的热稳定性提供理论依据。     

高性能热塑性弹性体HYBRAR对PP性能的影响

用熔融共混法制备了聚丙烯（PP）和两种牌号的高性能热塑性弹性体HYBRAR的共混物，其中HYBRAR的质量分数分别为0％、5％、10％、15％和20％。通过简支梁冲击和拉伸实验对共混体系的力学性能进行了表征，并用热重分析仪（TGA）测试了体系的热稳定性。结果表明：共混体系的冲击强度和断裂伸长率随着HYBRAR用量的增加大幅度提高，而拉伸强度则先降低后增加，HYBRAR7311的增韧效果比HYBRAR7125好；HYBRAR7125使PP的热稳定性发生不规律变化，而HYBRAR7311使PP的热稳定性先增加后降低。     

不同亚微观形态的聚丙烯/蒙脱土纳米复合材料的研究

通过控制不同的工艺条件,利用双螺杆挤出插层法制备出两种不同微观结构的聚丙烯／蒙脱土纳米复合材料。利用透射电子显做镜观察发现．分别制备出了插层型和半插层型聚丙烯／蒙脱土纳米复合材料,半插层型结构的材料中有机土分散更均匀,尺度更小。对两种纳米复合材料的物理性能测试表明,插层型纳米复合材料的缺口冲击强度提高幅度最大,同时耐热性并没有降低;半剥离型纳米复合材料的熔体质量流动速率降低幅度最大,屈服强度、弹性模量、耐热性提高幅度最大,缺口冲击强度略小于插层型。