产中性蛋白酶的枯草杆菌478的发酵及其基本特性

枯草芽孢杆菌478是为生皮脱毛选育的一株中性蛋白酶产生茵。500 ml 摇瓶,装量50 ml 培养基,接种一小铲,31℃摇床培养40小时,产酶为5502 u/ml。BF—12—Ⅰ型罐发酵28小时,31℃产酶为5795 u/ml。酶的酪蛋白水解最适 PH 为7.0,活性范围为 PH 6.5～7.5,此间热稳定性较好,40℃两小时失活为12%。酪蛋白水解的最适温度为40～50℃。Fe ~(++)Hg~(++)与 Cu 对酶有抑制作用,Ca~(++)与 Mg~(++)则有激活作用。聚丙烯酰胺凝胶电泳分析得到9条带。国内外一直沿用的硫化碱脱毛工艺对环境污染严重。酶法脱毛则是解决污染问题的可行途径。半个世纪以来人们对此作了积极的研究。然而,可用的产酶株仍是屈指可数,脱毛工艺的革新受到很大限制。为了推进酶法脱毛工艺向前发展,我们选育了脱毛效果较好的枯草芽孢杆菌478中性蛋白酶产生株。本文对该茵的发酵及其产生的中性蛋白酶的一些基木特性作一报导。     

A Case Study of Heat Transfer from Hot Runner Mould to the Fix Platen of the Injection-moulding Machine

In an injection moulding process, the parallelism b et ween the tie bars of the injection moulding machine is very important as it will affect the mould closing and clamping system. In recent years, more and more ho t runner systems are being applied in the moulding industry to save material and decrease the losses of injection pressure. Heat transfer from hot runner system from the fixed half which is secured in the fix machine platen could transmit s o much heat that it may cause high temperature diffe...     

办公自动化的发展趋势及策略

随着电子计算机及通讯技术为代表的信息技术的发展，办公信息处理作为机关、企事业单位的日常业务工作正日益普及和深入。分析了办公自动化的发展简史及当前我国的办公自动化系统的特点，提出了一些相应的观点和发展策略。     

猪肺疫流行原因与对策

通过对部分地区暴发A型巴氏杆菌病的调查研究，分析得出此病流行的主要原因是气候急剧变化、环境恶劣、饲养管理水平低下、菌株血清型改变、滥用抗生素等。其流行特征是以急性型最多，以肺炎症状和败血症状为主，部分病畜康复后可再次感染。提出了防治此病的有效措施。     

An alternative magnesium-based root canal disinfectant: Preliminary study of its effi cacy against Enterococcus faecalis and Candida albicans in vitro

Organisms invading root canal systems result in serious pulpal and periapical disease. To eliminate microorganisms and restrain secondary infections, dental materials with antibacterial properties are urgently needed in endodontics. Magnesium is considered as a promising biodegradable and biocompatible implant material. However, there are barely researches about its application in endodontic therapy. This work investigated the in vitro efficacy of magnesium powder against Enterococcus faecalis and Candida albicans compared with a common disinfectant, calcium hydroxide. With Calcium hydroxide served as a comparison it demonstrated the qualified antibacterial and anti-fungus properties of Mg as root canal disinfectant due to its high alkalinity of degradation, and the antimicrobial efficacy enhanced with the decreasing powder size.     

2,2′-(2,2′-联吡啶-4,4′-二次甲基)二丙二腈的合成及其表征

2,2′-联吡啶-4,4′-二甲醇在SeO2氧化作用下制得2,2′-联吡啶-4,4′-二甲醛,2,2′-联吡啶-4,4′-二甲醛与丙二腈在无催化条件下,成功地进行了Knoevenagel反应,合成了目标化合物2,2′-(2,2′-联吡啶-4,4′-二次甲基)二丙二腈,通过MS、1H NMR、元素分析及紫外-可见分光光度法对其进行了结构及性能表征,并探讨了其合成工艺.     

Study on the specific interaction between angiogenin and aptamer by atomic force microscopy （AFM）

The specific interaction between angiogenin and aptamer has been investigated by using AFM. The specificity of the interaction is revealed by comparing the binding probability of aptamer to other elements in a series of control experiments. The results have shown that there is specific interaction force between angiogenin and aptamer. Moreover, the single molecular pull-off force between angiogenin and aptamer has also been determined using the Poisson statistical method to be 133.7±11.7 pN. These findings obtained are helpful to the better revelation of recognition mechanism between angiogenin and aptamer, which provided basis for further understanding the inhibition of the aptamer to angiogenic activity.     

Monitoring p21 mRNA expression in living cell based on molecular beacon fluorescence increasing rate

Studying the expression level of mRNA in living cells will offer tremendous opportunities for advancement in cell biology research, disease diagnostics, and drug discovery. In this paper, a molecular beacon （MB） specific for the important tumor suppressor gene p21 has been designed and synthesized. The fluorescence signal was detected in real-time after the MB entered the cytoplasm of nasopharyngeal carcinoma cells. After injecting the p21MB into nasopharyngeal carcinoma cell and p33-transfected nasopharyngeal carcinoma cell, the consistent increase of fluorescent signal intensity was detected in both cell lines, and maximum fluorescence intensity achieved in about 15 min. In about 4 min following microinjection, the fluorescence increasing rate was significantly different between these two cell lines, which indicate the different p21 mRNA expression levels. The results obtained in the real-time detection were also validated by RT-PCR. Analysis of the initial fluorescence increasing rate can efficiently reduce the side effect of enzyme and improve the accuracy in living cell mRNA detection.     

基于激光散透比的牛乳脂肪测试技术研究

依据光散射原理,建立了利用散透比测量牛乳脂肪质量含量的理论模型,提出了牛乳脂肪质量含量的快速高准确度测量方法。实验结果表明,本方法能准确、快速的测量牛乳脂肪质量含量。