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关键词： 抗癌药物   紫杉醇   分离   工程菌株   构建  

关键词： 液膜   分离   环境工程  

摘要： 膜分离技术是发展十分迅速的新型分离技术,液膜分离技术是重要的膜分离技术之一,本文对液膜分离技术的种类、分离原理作了概要综述,着重介绍液膜分离技术在环境工程中的应用。

关键词： 绿色分离   绿色化学   过程集成   环境影响   精馏  

摘要： 本文通过对绿色化学、绿色化工技术及其实现方法的的分析，将“绿色”的思想引入到分离工程的研究和应用中，提出“绿色分离工程”的概念、研究内容和研究方法。 要实现绿色分离工程，首先要解决的是怎样评价过程系统对环境影响的问题。过程系统对环境产生影响主要是因为其向环境排放各种有害废物，据此提出影响流的概念。可以用一个表示化学物质对环境影响特性的值与该物质排放流率的乘积来表示此物质排放对环境影响的程度。过程系统对环境的影响即为各物质排放的影响流的总和。本论文综合了国内外各种评价化学物质对环境影响的方法，提出了化学物质的绿色指数。用本方法可以较好地评价各过程系统对环境的影响。 精馏是分离过程中典型的单元操作，因其能耗大，故考虑工艺排放废物对环境产生影响的同时，必须考虑能量消耗对环境的影响。在分析精馏过程特性的基础上，本论文提出一种适用于评价精馏过程环境影响的方法。 本文以巨化锦纶厂环己酮精馏系统为工程实例，根据不同流程的模拟结果，用本论文所提出的方法分析其环境影响，对比原始工艺流程和经过过程集成分析得到的流程，得出结论：过程集成是较好实现“绿色分离工程”的手段。

关键词： 表皮干细胞   干细胞群   表皮组织  

摘要： Nanostructural engineering of inorganic substrates by free radical graft polymerization was studied with the goal of developing new membrane materials for pervaporation. Graft polymerization consisted of modification of surface hydroxyls with vinyl trimethoxysilane, followed by solution graft polymerization reaction using either vinyl acetate (VAc) or vinyl pyrrolidone (VP). The topology of the modified surfaces was studied by atomic force microscopy (AFM) on both atomically smooth silicon wafer substrates and microporous inorganic membrane supports in order to deduce the effects of modification on the nanostructural properties of the membrane. While unmodified wafers showed a root-mean-square (RMS) surface roughness of 0.21 ± 0.03 nm, roughness increased to 3.15 ± 0.23 nm upon silylation. Under poor solvent conditions (i.e., air), surfaces modified with higher poly(vinyl acetate) (PVAc) or poly(vinyl pyrrolidone) (PVP) polymer graft yields displayed lateral inhomogeneities in the polymer layer. Although RMS surface roughness was nearly identical (0.81–0.85 nm) for PVAc-modified surfaces grafted at different monomer concentrations, the skewness of the height distribution decreased from 2.22 to 0.78 as polymer graft yield increased from 0.8 to 3.5 mg/m2. The polymer-modified surfaces were used to create inorganic pervaporation membranes consisting of a single macromolecular separation layer formed by graft polymerization. PVAc grafted silica membranes (500Å native pore size) were found selective for MTBE in the separation of 0.1–1% (v/v) MTBE from water, achieving MTBE enrichment factors as high as 371 at a permeate flux of 0.38 l/m2 hr and a Reynolds number of 6390; however, these membranes could not separate anhydrous organic mixtures. Pervaporative separation of methanol/MTBE mixtures was possible with PVAc and PVP-modified alumina supports of 50Å native pore size, where the separation layer consisted of grafted polymer chains with estimated radius of gyration 4.5

ISBN: (纸本)7801641590

关键词： 旋转流   PIV测试系统   流场   分离试验   工程应用  

摘要： 旋转流静止管式膜微滤是十字流强化微滤的有效方法之一，但由于其受到旋转剪切流、轴向剪切流及径向渗透流的三维流场作用，其流场特性有待探索，其分离特性也有待深化认识。本文通过PIV激光测试系统首次对聚丙烯（PA）旋转流管式膜流场进行了实测，并利用SiO2进行分离实验，比较两种不同的切向进料方式对过滤与分离的影响，并与普通十字流过滤进行比较，提出了旋转流膜管的再生方式。 首先通过采用先进的PIV测试系统，对旋转流膜器的径向环隙和切向环隙处的流场进行了实测，初步探讨了其流场特性，发现在无渗透流和有渗透流的情况下其流场并不相同，并与旋转动态膜的分离特性进行了比较。 第二、根据粒子的力平衡理论推导出旋转流中粒子不向膜面沉积的周向剪切速率及径向粒径的分布规律，并指出径向速度对粒子沉积的影响。 第三、采用SiO2进行了分离实验，比较了直线相切进料和园弧相切进料两种形式在不同压力和不同浓度下对渗透通量的影响及浓度、压力等对过滤通量的影响规律；并与普通十字流微滤进行了分析比较，发现不管是直线相切进料还是园弧相切进料其在相同工况下的过滤通量都比普通十字流的过滤通量大。通过实验还发现旋转流中要达到一个高的稳定通量其操作压力与其它强化方法比较有变小的趋势。 第四、对旋转流静止管式膜的再生进行了实验比较，并提出了旋转流膜管可以通过卸压再生，以减少膜管每次使用后的冲洗、反吹等辅助时间，采用该种方法再生的膜管其渗透通量完全能满足要求，当循环使用一定次数后再进行或冲洗或反吹或更换新膜管。 最后、将以上的研究成果应用于脱落酸（ABA）的三芯过滤分离中，发现其效果非常显著，提高过滤通量约40％，而且还降低了能耗。

关键词： 管养分离   运行机制   管理体制   效率低下   工程管理   管理队伍   管理单位   建设与管理   运行模式   计划经济体制  

摘要： 1 问题的提出1.1 管理体制不顺,管理效率低下在长期的计划经济体制下,黄河河道工程管理实行国家出资、职工建设与管理、沿黄群众投劳经济关系不清晰、管理形式单一的运行模式。由于治黄投资国家承担,管理队伍不断扩大,往往是建一处涵闸或河道整治工程,或者某某领导一句话,就组建一个河道管理单位,结果是管理人员数量与维护任务不协调;一个县级河道管理单位,管辖30～50km 堤线,管理人员高达300～500人,合每公里10～20人,可日常维护工作如隐患处理、堤坝管护与探测还要雇佣民工,造成工作效率低下,人力资源浪费。

关键词： Heat transfer  

摘要： This paper deals with the separation behavior of a press-molded glassware from the pressing mold surface. Since the separation of the glass from a mold surface affects the transcription of the glass shape from the mold, it is desirable to control the separation behavior in the practical press-molding of glassware. The separation or sticking of the glass is mainly influenced by thermal pressing conditions in practical molding. Hence, separation forces during the demolding process between glass and mold were measured under various pressing conditions. The results show that, under certain conditions, the glass sticks on the pressing surface of the mold even after the mold is removed from the pressed glass, and that the separation (sticking) force increases with rising initial temperature of glass and mold, increasing the pressing pressure, and with elongation of pressing duration. In order to interpret the obtained results, the separation forces were correlated to the interface temperature between glass and mold at the end of the pressing process. The correlation shows that the sticking force becomes evident when the interface temperature exceeds a certain temperature. Under the experimental conditions, the threshold temperature was about 660°C, and was slightly lower than the "softening temperature" of the glass used. From the results, it is concluded that the separation behavior of a press-molded glassware is dominated by the interface temperature between glass and mold at the end of the pressing process. © 2001 Scripta Technica, Heat Trans Asian Res, 30(8): 660-675, 2001.

关键词： Capital budgeting   Project management   Investment decisions   Limited liability   Acquisition costs   Incentive pay   Capital investments   Proxy reporting   Proxy statements  

摘要： The paper analyzes the question who should be provided with incentives to acquire and reveal information about the quality of an investment proposal: the division manager, who derives private benefits of control from the project and always wants to invest, or the capital budgeting department, which has no personal interests in the decision. Interestingly, private benefits of control may reduce expected wage costs. In this case joint project evaluation and project management is optimal.