Studies of substrate specificities of lipases from different sources

Although lipases are widely applied in a wide variety of reactions, available information on the factors that are responsible for the substrate specificities of lipases from different sources is scarce. In this paper, nine lipase‐producing microorganism strains were isolated from oil‐containing samples. The properties of these enzymes, including pH optima, temperature optima, thermal stability, and pH stability, vary significantly with the different sources from which these lipases were isolated. The substrate specificities of the nine lipases, including fatty acid and positional specificities, were also studied. The fatty acid specificities of the nine lipases were observably different toward 15 substrates with different carbon chain lengths, different saturation degrees and different side chains. The lipases from S₃ Penicillium citrinum (PCL), MJ₁ Aspergillus niger (ANL), MJ₂ Aspergillus oryzae (AOL), YM Bacillus coughing (BCL), S₉ Geotrichum candidum (GCL), and S₁₁ Candida lypolytica (CLL) showed the strongest specificities to short‐chain esters, and the other lipases showed strong selectivity for medium‐ or long‐chain and branched esters. The positional specificities were examined by analyzing the hydrolytic products of triolein catalyzed by the nine lipases, using TLC. The lipases can be mainly classified into two groups by their specificities for the ester bond at position 2 of triglycerides; one group can selectively hydrolyze the ester bond at position 2 of the triglycerides, the other group cannot. All these nine lipases were divided into four groups by hierarchical clustering analysis on the basis of the results of fatty acid and positional specificities.     

不同品种甜菜类型甜菜光合特性的研究

水文研究了甜菜生育期中不同品种类型甜菜的光合特性，结果表明在生育前期，高糖型品种的叶绿素含量高，而生育中前期以丰产型高，标准型介于二者之间，ＲｕＢＰ竣化酶活性的动态变化亦显这种趋势；在叶丛形成期和块根增长期，丰产型品种光合速度最高，在糖分积累期则以高糖型品种光合速度高；不同品种不同叶位的叶绿素含量与光合速率中呈正相关。     

2—叠氮—1萘醌—5—磺酸生产工艺优化

研究以L-酸为原料,对合成用于制作PS版的2-叠氮1-萘醌-5-磺酸的亚硝化、还原及重氮化三步生产工艺进行最佳配比选优试验。结果表明对L-酸的总收率可达73-75％.获得了较高的收率。     

流延热释电厚膜陶瓷制备单元红外探测器

本文报道采用流延法制备的热释电厚膜陶瓷材料直接装配的单元红外探测器，该方法大大简化了目前探测器的制备工艺，极大地提高了材料的利用率，器件的性能也达到了目前探测器的水平。     

知识库系统中的一种并发控制方法

本文给出了一个基于ＤＡＴＡＬＯＧ环境的知识库并发控制算法，算法的基础是两段锁（ＴＷＯＰＨＡＳＥＬＯＣＫＩＮＧ），它使用了相关和覆盖的概念，减少了被锁对象的数目，从而提高了系统的效率．最后给出了算法的正确性证明．     

Robust control of nonlinear uncertain systems without generalizedmatching conditions

A novel procedure, called recursive-interlacing procedure, is proposed for designing globally stabilizing robust control. The procedure introduces new interlacing steps and combines them with the existing recursive or backstepping design. It is shown by examining all possible third-order vector systems that the procedure is applicable to systems not satisfying any of the existing structural conditions, that is, to systems in which uncertainties are potentially anywhere and of any bounding function. By its nature, the procedure is not limited to systems of any specific order; it either produces stabilizing control or reveals certain measure of unstabilizability, and it includes recursive design as a special case     

合成镁白云石砂的研制与应用

选用优质轻烧白云石、轻烧菱镁石为原料,经干法消化、高温煅烧,制得杂质含量2.66％、体密>3.28g/cm~3的合成镁白云石砂。用合成镁白云石砂制得CaO MgO>97％,总杂质含量2.11％的高纯合成镁白云石砖,在太原钢铁公司AOD炉第一次试用,最高炉令达36炉次。     

新时期高校教师岗前培训工作的建议

本文分析了高校教师岗前培训工作的必要性，针对新时期岗前培训工作存在的几个不足，提出提高认识，加强岗前培训管理，创新培训内容和形式，完善考核机制的几点建议。