Structural definition by antibody engineering of an idiotypic determinant

Using computer-aided techniques for predicting molecular structure,we constructed an atomic model of the variable domain of a murineanti-thyroglobulin antibody whose immunodominant idiotypic determinant(Id62) was mapped by site-directed mutagenesis and immunochemicalanalysis. We previously showed that under experimental conditionsthis idiotype activates anti-idiotypic B cells and T cells,and modulates the response to thyroglobulin in mice. Becauseidiotype interactions are considered of physiological importancefor immune regulation, we studied this idiotype as a model tounderstand the relationship between function and structure.To determine the contribution of heavy- and light-chain variabledomains to the idiotype structure, we constructed chimeric expressionvectors and introduced them into the (non-secreting) P3X63Ag8.653myeloma cell line. Mutants of the heavy-chain variable domainwere obtained by site-directed mutagenesis and transfected intothe murine (₁) light-chain producer J558L cell line. The expressedproteins were purified from culture supernatants of transfectedcells and characterized. We provide evidence that the thirdhypervariable loop (D region) of the heavy-chain variable domainis the structural correlate of the idiotypic determinant ofthis autoantibody and is independent from the nature of theassociated light chain. Substitution of residues of the firstand second complementarity-determining regions do not affectidiotype expression. The results described here are discussedin relation to our understanding, at a molecular level, of theinteraction of idiotopes with B- and T-cell compartments.     

Hydrogenation to convert CO2 to C1 chemicals: Technical comparison of different alternatives by process simulation

Carbon dioxide (CO₂) conversion by catalytic reaction with hydrogen to produce different C1 chemicals is a promising strategy in view of the development of a sustainable chemical industry. In this work, two CO₂ hydrogenation routes are investigated in detail, respectively syngas and formic acid syntheses. Starting from published experimental reaction data, simulation models based on a kinetic analysis were developed and implemented in Aspen Plus process simulator. The two processes are analyzed according to a number of selected technological indicators, comprising CO₂ conversion, specific H₂ consumption, product yield, energy duties, and carbon emissions. To extend our study, three additional CO₂ conversion pathways are considered, respectively methanol, methane, and urea syntheses, whose technological performances were retrieved from similar studies available in the scientific literature. Under the assumption that H₂ is available from renewable sources, our results highlight that CO₂ conversion routes towards fuel compounds (ie, syngas and methane) look particularly appealing from the energy balance point of view. If non-renewable energy is used to produce H₂, the actual environmental benefits (in terms of net CO₂ emissions) strongly depend on the country-specific carbon intensity for electricity generation.     

动态模拟技术与化学工程

介绍了化工过程动态模拟技术及相应软件的发展与应用状况 ,总结了动态模拟技术的最新进展。指出动态模拟技术应当与动态优化技术相结合 ,动态计算机网络管理将实现石油化工过程的连续实时优化 ,动态模拟技术将向工艺流程和生产方案的合成、能量系统集成、结合生态工业园区实例进行动态流程模拟等方向发展     

分子模拟与化学工程

从分子水平来研究化工过程及产品的开发和设计是21世纪化学工程的一个重要方向.综述了计算机分子模拟中的MonteCarlo分子模拟和分子动力学模拟两种方法及其在化工中的应用,涉及分子模拟在建立状态方程和研究分子微观结构、相界面、扩散性质等方面的应用进展.指出分子模拟对化学工程的基础研究、工艺过程以及新产品开发将发挥巨大作用.     

硫酸装置设计工具的进步--从计算尺到动力学模拟

仅仅在30年以前，工程设计还是由工程师滑动和阅读用石墨润滑的多刻度计算尺来完成的，其设计水平部分由操作技巧而决定。装置的操作计算要用铅笔一笔一画地进行，而技术改造则包含着相当繁复的前期计算。     

如何将DVD-R中的资料转入DTL数据磁带中

随着DVD-R产品的日益普及,很多音像公司和软件公司开始采用DVD-R作为信息的载体将数据传送给复制厂家。而DVD-R在传递数据的时候有时会出现在驱动器中读取没有问题,但在母盘制作设备的驱动器中读取出现问题的情况。笔者曾在复制企业中碰到过这种情况。而如果将数据直接复制到DTL数据磁带上,由于数据格式不同其信息并不可用。通常的做法是通过一个采集卡将数据转换正符合DTL数据带兼容的格式。     

创建国际型工程公司的思考

对我国勘察设计研究院在社会主义市场经济的条件下,其地位,职丽,任务的变化进行了分析提出应创立国际型工程公司,并就其组织模式,需要的基本条件等进行具体论述。     

Potential of genetic algorithms in protein folding and protein engineering simulations

Genetic algorithms are very efficient search mechanisms whichmutate, recombine and select amongst tentative solutions toa problem until a near optimal one is achieved. We introducethem as a new tool to study proteins. The identification andmotivation for different fitness functions is discussed. Theevolution of the zinc finger sequence motif from a random startis modelled. User specified changes of the repressor structurewere simulated and critical sites and exchanges for mutagenesisidentified. Vast conformational spaces are efficiently searchedas illustrated by the ab initio folding of a model protein ofa four ß strand bundle. The genetic algorithm simulationwhich mimicked important folding constraints as overall hydrophobicpackaging and a propensity of the betaphilic residues for transpositions achieved a unique fold. Cooperativity in the ßstrand regions and a length of 3–5 for the interconnectingloops was critical. Specific interaction sites were considerablyless effective in driving the fold.     

Hands-on kinetic measurements and simulation for chemical process engineering students

Hands-on experience in the laboratory is essential in chemical engineering education to enhance the understanding of abstract theories and their effect on chemical processes. In this work, we describe a laboratory class, which combines some of the main engineering concepts into a set of hands-on experiments and simulations. Students are introduced to an iodine clock reaction performed in multiple different reactor types and are instructed to determine the reaction kinetics. Subsequent analysis of the experimental data in Python teaches basic programming skills and the concepts of numeric integration and optimization. Finally, a digital twin of one of the reactors is developed in COMSOL Multiphysics to give the students an application-focused introduction to more-dimensional multiphysics modeling. The students thereby get practical insights into the different methods and stages of reactor and reaction engineering. Based on the students’ assignments, we consistently see a deeper understanding of reaction kinetics and reactor engineering than in the accompanying traditional lecture.     

Charge engineering of a protein domain to allow efficient ion-exchange recovery

We have created protein domains with extreme surface charge.These mutated domains allow for ion-exchange chromatographyunder conditions favourable for selective and efficient capture,using Escherichia coli as a host organism. The staphylococcalprotein A-derived domain Z (Z_wt) was used as a scaffold whenconstructing two mutants, Z_basic1 and Z_basic2, with high positivesurface charge. Far-ultraviolet circular dichroism measurementsshowed that they have a secondary structure content comparableto the parental molecule Z_wt. Although melting temperatures(T_m) of the engineered domains were lower than that of the wild-typeZ domain, both mutants could be produced successfully as intracellularfull-length products in E.coli and purified to homogeneity byion-exchange chromatography. Further studies performed on Z_basic1and Z_basic2 showed that they were able to bind to a cation exchangereven at pH values in the 9 to 11 range. A gene fusion betweenZ_basic2 and the acidic human serum albumin binding domain (ABD),derived from streptococcal protein G, was also constructed.The gene product Z_basic2–ABD could be purified using cation-exchangechromatography from a whole cell lysate to more than 90% purity.     

Experimental methods in chemical engineering: Process simulation

Process simulation software designs equipment, simulates operations, optimizes a plant's configuration (heat exchangers network, for example), estimates operating and capital expenses, and serves as an educational tool. However, mastering the theoretical background minimizes common mistakes such as applying an incorrect thermodynamic method, selecting improper algorithms in the case of tear systems, and setting irrational system specifications. Engineers and researchers will exploit this tool more often in the future as constant advancements in simulation science as well as new models are released continually. Process simulators make it easier to build digital twins and thus will facilitate the implementation of the industry 4.0 guidelines. We highlight the mathematical and technical features of process simulators, as well as the capabilities and the fields of application. A bibliometric map of keywords from articles citing Aspen+, Aspen plus, Hysys, and Pro/II indexed by Web of Science between 2017 and 2020 identified the main research clusters, such as design, optimization, energy or exergy, biomass; H₂ and CO₂ capture, thermodynamics; and separations and techno-economic analysis.     

iGES--一个人工智能图形工程系统

介绍了一个建立在G2专家系统之上的集成的人工智能图形系统。将已有的优秀商用软件集成在一起,其中包括信息系统(PI)、稳态模拟(HYSYS)、过程分析(Processinsight)、过程优化(NOVA