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关键词： 水处理   环境工程   膜分离技术   应用  

摘要： 随着环境的不断恶化,人们环保意识的提高,污染排放问题逐步受到了各界的关注,而如何采取有效措施来处理与回收利用水资源成为了环境工程的重要任务.企业能够根据实际生产需要对膜分离技术进行合理选用,及时对生产过程中产生的污水及废物进行清除,将其对环境带来的不利影响降至最低,在保证生产过程顺利进行的情况下为人们提供良好的生活环境.基于此本文分析了水处理环境工程中膜分离技术的应用.

关键词： 胆固醇氧化酶   多功能酶   酶的催化混乱性   蛋白质工程   生物转化  

摘要： 目的:从天然环境中筛选高胆固醇氧化酶活性的菌株,对其进行鉴定,分离酶基因,将其体外基因重组并进行蛋白质工程修饰,以提高酶活性。方法:(1)以胆固醇为唯一碳源,初筛含胆固醇氧化酶的菌株。将菌株接种到液体养基中进行恒温培养,对培养液上清进行硅胶薄层层析检测。选取有明显新产物斑点产生的培养液进行气相色谱-质谱检测,筛选高胆固醇氧化酶活性的菌株。通过试剂盒提取得到菌株的基因组,并进行16SrDNA序列比对,确定菌株种属。(2)选择一株菌株进行培养,细胞破碎后进行盐析、弱阴离子交换层析、疏水层析和分子筛层析,得到胆固醇氧化酶纯品。通过Edman法和羧肽酶法测得该酶氨基酸链两端的残基序列,在数据库中比对得到编码基因序列。基因通过聚合酶链式反应扩增、重组和转化导入***10细胞并表达,对其产物进行纯化。(3)测定酶的最适pH、最适温度、有机溶剂耐受性以及底物谱等理化性质。(4)制作酶的三维模型,并与底物分子对接,根据模型选择位点进行饱和突变和表达。纯化突变体的高胆固醇氧化酶并测定其理化性质。结果:通过筛选得到了 3株高效菌株,鉴定结果分别为Cellulosimicrobium,Stenotrophomonas sp.和 Arthrobacter sp.,选择 Arthrobacter sp.为研究对象,并得到胆固醇氧化酶。该酶最适pH为7,最适温度为40℃,在最适条件下Km为1.41mM/L,酶活力为94.7U/mg。其对N,N-二甲基甲酰胺、甲醇和二甲基亚砜表现出良好的有机溶剂耐受性。其可转化的底物包括胆固醇、β-谷甾醇、孕烯醇酮和手性化合物3,5,5-三甲基-2-环己烯-1-醇等,其中对3,5,5-三甲基-2-环己烯-1-醇几乎没有手性选择性。根据三维对接模型选择了底物结合口袋中的Glu144,Gly160和Asn164位点进行饱和突变。其中Glu144位点变为Tyr后该酶对底物3,5,5-三甲基-2-环己烯-1-醇的催化活性可以提高5倍,且对底物的手性选择性达到9.8%;Glu144位点变为Met后可使该酶对底物的手性选择性达到14.92%;Gly160位点突变为Thr后该酶对底物胆固醇的催化活性可提高565.77%。结论:筛选出含胆固醇氧化酶的菌株,并得到其编码基因,且成功对其进行克隆,得到表达产物并进行纯化和其理化性质分析。对该酶进行饱和突变改造,有效地提高了对特定底物的活性,提高了对底物的立体结构选择性。

关键词： Engineering faculty   gender   women in engineering   underrepresentation  

摘要： Women's persistent underrepresentation in undergraduate engineering is a well-documented concern. One issue missing from many discussions on the topic, however, is that women are not equally underrepresented in all engineering majors. Furthermore, a significant portion of the research focuses solely on women's experiences within engineering. We know far less about how key stakeholders, such as faculty, understand gender stratification in engineering education. Faculty are influential figures who have been shown to play a central role in introducing students to the profession and can significantly impact students' experiences. This article addresses these gaps by examining the reasons engineering professors provide to explain women's underrepresentation across majors. Using data from 23 in-depth interviews at one university, the findings demonstrate how the majority of faculty mobilize gendered images to position some majors as feminine and others as masculine, and then suggest that this impacts women's choices of fields. Chemical engineering, however, served as an interesting case in this study because it was described as gender diverse. These findings contribute to discussions about the construction of gendered cultures within engineering and show how engineering faculty play a role in this process.

关键词： 大肠杆菌   琥珀酸   基因工程   二氧化碳   琥珀酸分离  

摘要： 琥珀酸是一种非常重要的C4平台化合物是合成很多重要产品的中间化合物,以琥珀酸为基础的化学衍生产品在工业、农业、食品、医疗等领域有着巨大的应用价值。发酵法产琥珀酸以可再生能源为原料通过微生物转化的方法生产琥珀酸作为一种绿色环保的方法较传统的以石油为原料生产琥珀酸有着巨大的优势。本文在实验室已构建的大肠杆菌工程菌WS100的基础上,通过λRed同源重组系统,敲除其丙酮醛合成酶基因（mgsA）,再通过无氧管培养得到菌株WS102,进一步消除副产物乳酸的代谢。通过NBS培养基发酵罐验证,得到的发酵液琥珀酸含量64.9 g/L,琥珀酸的质量收率为75.1%,且发酵液中无副产物乳酸检出,而WS100琥珀酸收率72.3%。在此基础上进行WS102利用二氧化碳发酵琥珀酸的研究,研究发现全阶段以二氧化碳气体发酵琥珀酸并不能很好的产琥珀酸,前期的厌氧条件容易造成代谢失衡,产生大量副产物乙酸,在NBS培养基中发酵琥珀酸产量和收率分别为52.65 g/L和68.9%。因此,通过单因素的比较设计一条微好氧-厌氧的发酵工艺,通过在前期添加KHCO3保证菌体良好生长,在稳定期之前以K2CO3提供固定“CO2”所需C源,通过搅拌使前期保持微好氧的状态,在稳定期以后通二氧化碳气体进行琥珀酸发酵的工艺。通过在NBS培养基中分批发酵得到琥珀酸产量为58.3g/L,琥珀酸的质量收率为73.1%,生产强度为0.972 g/L·h。在此基础上进行分批补料发酵,琥珀酸产量为76.5 g/L,琥珀酸的生产强度和质量收率分别为1.063 g/L·h和76.5%。本文最后以钙盐法分离提取发酵液中的琥珀酸,工艺路线为首先将发酵液通过简单的加热过滤除去大颗粒物质,然后通过陶瓷膜过滤去除绝大部分菌体,通过钙盐沉淀,活性炭脱色以及离子交换的方法分离提取发酵液中的琥珀酸。并且对钙化工艺做了优化,优化钙化反应条件为在80℃条件下添加等体积的30%氯化钙溶液反应30 min。最终得到琥珀酸结晶99.6 g,琥珀酸收率为56.8%。

关键词： HYDROCARBON separation   LIQUEFIED natural gas   SHALE gas   ADSORPTION   PROPENE  

摘要： Recent increases in shale gas production provide an excellent opportunity for advancements in the energy-efficient separation of natural gas liquids because these are increasingly used as fuel sources and chemical feedstocks. Current fractionation schemes generally involve cryogenic distillation of C-1-C-4 hydrocarbons and are extremely energy intensive. Here, we describe the first steps toward a lower energy, kinetic pressure-swing-adsorption cycle for the separation of ethane, propane, propylene, and butane using ZIF-8 as a diffusionally selective adsorbent. Crystal engineering techniques were employed to control the diffusive time scale of the separation, allowing for multiple separations using the same adsorbent within reasonable process times. Equimolar separation of ethane/propane mixtures at 293 K exhibited separation factors of 2.7 in the gas phase under nonoptimized conditions, which enhances the concentration of the feed mixture to 7.5 mol % propane. The separation performance was shown to improve to 3.8 at lower temperatures (81 mol % propane), which is attributed to differences in the activation energy of permeation of the two components. Propane/butane mixtures demonstrated a lower diffusive selectivity and almost negligible enhancement, while propylene/propane showed enhancement beyond ethane/propane due to a strong diffusive selectivity and sorption selectivities closer to unity. Single-component adsorption and diffusion results were incorporated into a computational model of the system and shown to be in relatively good agreement with the experimental values. The model was used to predict the separation system performance and recovery at various temperatures.

关键词： 化工分离工程   理论教学   实践教学   改革  

摘要： 化工分离工程课程教学由理论教学和实践教学两个部分组成,本文分析了化工分离工程课程教学中存在的问题,并结合教学实践,提出理论教学和实践教学改革的措施,重在激发学生的学习兴趣,提高学生的实践能力,实现理论联系实际,培养高素质的化工人才。

关键词： 应用型人才   分离工程   精馏   教学改革  

摘要： 文章以化工专业本科课程化工分离工程精馏部分教学为教学改革的切入点,从课堂教学方法及课程考核方式改革方面重点介绍了适合应用型人才培养目标的教学体系,结合教学实践进行初步尝试,培养学生的实践能力,提高学生的专业素质。

关键词： software reliability engineering   software testing and debugging   nonhomogenous Poisson process   imperfect fault debugging   fault debugging complexity  

摘要： In the software reliability engineering literature, few attempts have been made to study the fault debugging environment using discrete-time modelling. Most endeavours assume that a detected fault to have been either immediately removed or is perfectly debugged. Such discrete-time models may be used for any debugging environment and may be termed black-box, which are used without having prior knowledge about the nature of the fault being debugged. However, if one has to develop a white-box model, one needs to be cognizant of the debugging environment. During debugging, there are numerous factors that affect the debugging process. These factors may include the internal, for example, fault density, and fault debugging complexity and the external that originates in the debugging environment itself, such as the skills of the debugging team and the debugging effort expenditures. Hence, the debugging environment fault removal may take a longer time after having been detected. Therefore, it is imperative to clearly understand the testing and debugging environment and, hence, the urgency to develop a model. The model ought to take into account the fault debugging complexity and incorporate the learning phenomenon of the debugger under imperfect debugging environment. This objective dictates developing a framework through an integrated modelling approach based on nonhomogenous Poisson process that incorporates these realistic factors during the fault debugging process. Actual software reliability data have been used to demonstrate applicability of the proposed integrated framework. Copyright (C) 2016 John Wiley & Sons, Ltd.

关键词： 磁分离技术   水处理   工艺  

摘要： 磁分离技术作为水处理工程中的新型技术,具有分离速率高、占地面积小、绿色环保等优势。水污染日益严重,加强对磁分离技术在水处理工程中的应用分析,对有效解决水污染问题具有积极的现实意义。论文简要分析了磁分离技术在水处理工程中的应用工艺及发展趋势,以供参考和借鉴。

关键词： 膜分离技术   环境工程中   应用   分析  

摘要： 膜分离技术是近几年迅速崛起的一项高新技术,经过近半个世纪的发展,膜分离技术越加成熟,并越来越多的应用到生物工程、石油化工工程、医药工业、食品工业、饮水处理工业等众多领域。在环境工程中,应用膜分离技术能有效保护环境。本文主要探讨了膜分离技术的相应原理,还介绍了国内外几种膜分离技术的类型,并着重介绍了膜分离技术在水处理环境中的应用,从而造福于环境工程。