An integrated downstream processing strategy for the recovery and partial purification of penicillin acylase from crude media

An integrated process strategy for the recovery of penicillin acylase was developed, based on precipitation of non‐enzymatic proteins directly from Escherichia coli homogenates or crude extracts using Rolquat (quaternary ammonium salt) and adsorption of the enzyme on Amp‐Seph (3.8 µmole ampicillin cm^?3) under pseudo‐affinity conditions. The effect of pH, concentrations of ammonium sulfate and Rolquat, and also concentrations of protein and cell debris on the precipitation of non‐enzymatic proteins from homogenates and crude extracts of penicillin acylase were analysed. The method of addition of Rolquat to homogenates and crude extracts significantly influenced the size of the precipitated particles. Improved results on the specific activity of penicillin acylase were obtained for 22% and 1% (w/v) of ammonium sulfate and Rolquat, respectively, added sequentially to enzyme solutions and at room temperature. Under these experimental conditions, the specific activity of penicillin acylase in homogenates and crude extracts was enhanced 2.5–3.0‐fold. Finally, the integrated process strategy was implemented first by precipitation of non‐enzymatic proteins and recovery of penicillin acylase directly from the enzyme solution treated with Rolquat using an adsorption/filtration system with an overall yield of 86%. This system allows simultaneously the filtration of cell debris and fine precipitated particles, in situ recovery of penicillin acylase by its adsorption on Amp‐Seph, and selective desorption of the enzyme with a specific activity of 11 IU (mg prot)^?1 and a desorption yield of 95%. © 2002 Society of Chemical Industry     

高压CO_2和乙醇协同沉淀法从牛乳中分离蛋白质的研究

以CO2 为沉淀剂 ,乙醇为CO2 助溶剂 ,考察了高压CO2 和乙醇对牛乳中蛋白质的协同沉淀作用。结果表明 :牛乳中蛋白质的沉淀存在着临界温度和临界压力 ,分别为 3 2℃和2 76MPa ,当体系高于这个临界温度和临界压力时对沉淀过程有利 ;CO2 和乙醇对牛乳中蛋白质的沉淀具有双重作用 ,在水体系中加入乙醇既有助于增加CO2 的溶解度 ,也可以使沉淀的临界温度和临界压力降低     

A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation

Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.     

不锈钢热轧浊环水处理工艺设计

介绍了宝钢集团上海五钢不锈钢长型材热轧工程浊循环水处理的工艺设计，探讨了采用化学除油工艺、自动反清洗过滤器等技术和设备，处理不锈钢热轧浊环水的技术特点。     

从混联法生产中提取镓的研究

针对联合法厂家资源的分布特点,提出采用化学法和树脂吸附法相结合的方式实现同时回收烧结法和拜尔法循环母液中镓的新工艺,并通过小试和扩试结果分析,阐述了该工艺的可行性。     

高压静电除垢技术在发电厂汽轮机凝汽器中的应用

汽轮机凝汽器的除垢问题通常采用化学方法或物理方法,这些除垢措施有一定的局限性。介绍了一种利用高压静电除垢技术。     

Necessary and Sufficient Conditions of Existence of Extreme Distributions F 5 – F 7 in the Generalized Chebyshev Inequalities Problem. Part II

The optimization problem for a linear functional on the set of distribution functions with two fixed power moments is considered. New criteria are proposed for the existence of the extreme distributions, on which a linear functional may take on the extremum value.     

A polynomial dynamic system approach to software design for attractivity requirement

Because of the widespread increasing application of Web services and autonomic computing, self-adaptive software is an area gaining increasing importance. Control theory provides a theoretical foundation for self-adaptive software. In this paper, we propose the use of the supervisory control theory of discrete event dynamic systems (DEDS) to provide a rigorous foundation for designing software for reactive systems. This paper focuses in particular on design of software with an attractivity requirement. It studies this problem using the polynomial dynamic system (PDS) model of DEDS. A necessary and sufficient condition for software existence and two algorithms for such software design are presented.     

Individual differences in children's event memory reports and the narrative elaboration technique.

Children between 7 and 8 years old took pan in a staged event at school and 1 week later were assessed using a short form of the Wechsler Intelligence scale for children (third edition) and measures of metamemory, narrative ability, and socioeconomic status. Two weeks following the event, children either received narrative elaboration training (NET; K.J. Saywitz & L. Snyder, 1996) and were prompted with the four NET cue cards at interview; received verbal prompts corresponding to the cue card categories, but without prior training; or were presented with the cards at interview without prior training. Children given verbal labels as prompts recalled as much information as children who received NET training and cue cards. Measures of intelligence were predictive of amount recalled for cards-only children but not for the other 2 groups, indicating that differences in recall between low- and high-IQ groups were attenuated when recall was supported by NET training or verbal prompting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)