A rapid and accurate 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetric assay for quantification of bacteriocins with nisin as an example

The objective of this study is to propose a more accurate and faster MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] colorimetric assay (MCA) for quantitative measurement of polypeptide bacteriocins in solutions with nisin as an example. After an initial incubation of nisin and indicator bacterium Micrococcus luteus NCIB 8166 in tubes, MTT was added for another incubation period. After that, nisin was quantified by estimating the number of viable bacteria based on measuring the amount of purple formazan produced by cleavage of yellow tetrazolium salt MTT. Then MCA was compared to a standard agar diffusion assay (ADA). The results suggested a high correlation coefficient (r ²=0.975±0.004) between optical density (OD) and the inhibitory effect of nisin on a bacterial strain Micrococcus luteus NCIB 8166 at a range of 0.125~32 IU/ml. The MCA described in this study was very quick. Quantification of nisin took only 7~8 h and the detection limit was at the level of 0.125 IU/ml when compared to 12 IU/ml and 24~28 h for ADA. The MCA provides an accurate and rapid method for quantification of nisin in solutions and is expected to be used for quantification of other antimicrobial substances.     

太中银线吕梁段方案研究

文章以太中银线吕梁段方案为例,分析了影响线路方案的主要因素,强调了线路选线过程中的主要技术标准以及与地方规划协调的重要性。     

HACCP在石油行业野外施工食堂中应用的绩效分析

将HACCP这一世界公认的食品安全控制系统引入野外施工食堂卫生管理当中.方法采用文献检索,事故分析、现场调查和Delphi等研究方法,通过对野外施工食源性疾病危害分析、建立关键控制点,形成野外施工食堂管理HACCP管理规范,并组织实施.结果实施HACCP体系后,从业人员手、餐具、菜墩、抹布的抽查合格率有显著提高,食堂从业人员以及参加施工人员对饮食卫生以及食堂卫生管理知识的掌握显著提高.结论在野外施工食品卫生管理中引入HACCP管理体系,控制食源性疾病取得了良好的绩效.     

A Digital Right Management Model for Distribution of Digital Audiovisual Content

0 IntroductionDue to the success of Internet technology and the emer-gence of wide band network,downloading encoded dig-ital audiovisual content files via HTTP,FTP,etc ,had gainedfavor amongInternet users because of thei mmediate access todesired content . Digital Right Management (DRM) system,can satisfy the content provider by encrypting digital audiovi-sual content andli miting access to onlythose people who haveacquired a proper license to play backthe content[1].DRMas defined bythe …     

完全体外化牛细胞核移植的研究

本研究探讨了用体外成熟卵母细胞和体外受精胚胎进行核移植的可能性。本研究结果在我国首次获得牛核移植的成功。从屠宰场回收的卵巢中抽取卵球－卵母细胞复合体，采用以前报道的方法（石德顺等，广西农业大学学报’１９９４：１３：１－５）进行体外成熟（ＩＶＭ）和体外受精（ＩＶＦ），获得ＩＶＭ卵母细胞和ＩＶＦ胚胎，体外成熟２３－２４ｈ后，在含０．１％透明质酸酶的无钙镁ＰＢＳ（ＰＢＳ）内，用细管反复吹打去掉卵丘细胞。选择具有明显第一极体的卵母细胞通过显微操作移去第一极体及其附近约一半的细胞质进行去核，去核的卵细胞在成熟液内继续培养到ＩＶＭ３０ｈ．体外发育到８－３２细胞期的ＩＶＦ胚胎用作核供体．供体胚胎用含０．２５％Ｐｒｏｎａｓｅ（溶于ＰＢＳ￣－）溶解透明带，并用细管吹打将其分散成单个卵裂球，在ＩＶＭ３０ｈ将单个卵裂球显微注入去核卵母细胞的卵周隙内，并在ＩＶＭ３１ｈ用８０Ｖ／ｍｍ４０μｓ两次电脉冲（间隔１秒）来诱导卵裂球与去核卵母细胞的融合。融合卵在颗粒细胞单层培养滴内共培养，体外培养２４ｈ后观察卵裂结果，经体外培养５－８天后发育到桑椹和囊胚的核移植胚胎移植到同期发情的受体．２个月后直检妊娠情况．本实验中共操作１９４枚卵母细胞，     

钢筋混凝土桁架筒的分析与研究

就钢筋混凝土桥架简体系进行了初步的分析与研究，表明这种结构体系有着良好的力学性能、抗震性能，且经济效益显著，有广阔的发展前景。     

高校图书馆工作人员的信息素养

本文从图书馆发展需要与图书馆员自身发展的需要出发,论述了图书馆员应具备的信息素养,阐述了信息素养的内涵,分析了图书馆员信息素养的现状,并提出了培养图书馆员信息素养的举措。     

亚硝基血红色素食品着色剂的研究

本文以健康的猪、牛、羊的新鲜牲血为原料，经化学提取、合成及酶解等简单步骤、研制成了亚硝基血红色素食品着色剂。该产品可替代具有毒性作用的亚硝酸盐而直接加入食品着色，是一种无毒副作用的理想的调味食品着色剂，同时也增强了食品的营成份。