二烯丙基硫醚的研究进展

二烯丙基二硫醚是大蒜素的有效成分。综述了大蒜素的提取和制备合成方法,即生物提取法和化学合成法,并介绍了生物提取法中的水蒸气蒸馏法、溶剂萃取法、超临界CO2萃取法等。提出生物提取法提取大蒜素成本高、转化率低;化学合成法合成大蒜素,制取率为87%~93%,得到的大蒜素粉剂有效成分纯度高,药效显著,价格低廉,建议采用化学合成法合成大蒜。     

由天然左旋多巴合成左旋多巴醇的研究

从广西天然黎豆中提取得到的左旋多巴(Ⅰ)为原料,通过酯化反应得到左旋多巴乙酯(Ⅱ)。采用NaBH4-CeCl3、NaBH4-LiCl、NaBH4-CaCl2作为还原体系,在无水乙醇溶剂中,将左旋多巴乙酯(Ⅱ)还原为左旋多巴醇(Ⅲ)。结果表明,采用NaBH4-CeCl3作为还原体系,有产率高,速度快等优点。该反应中首次采用天然氨基酸合成氨基醇,并采用NaBH4-CeCl3作为还原体系这种新的还原方法。     

一种新手性氨基醇的合成

以从广西天然藜豆中提取得到的左旋多巴（Ⅰ）为原料,通过酯化反应得到左旋多巴乙酯（Ⅱ）。采用NaBH4-CeCl3、NaSn4一LiCl、NaBH1＋．CaCl2作为还原体系,在无水乙醇溶剂中,将左旋多巴乙酯（Ⅱ）还原为左旋多巴醇（Ⅲ）。结果表明,采用NaBH4．CeCl,作为还原体系,有产率高、速度快等优点。该反应中首次采用天然氨基酸合成氨基醇,并采用NaBH。一CeCl,作为还原体系这种新的还原方法。     

右旋龙脑的应用及生产方法

介绍天然右旋龙脑的应用,并重点介绍从植物中提取右旋龙脑的进展,讨论了化学法和生物法合成生产右旋龙脑的可行性。     

代谢工程改造酵母生产香料的研究进展

天然产物香料作为食品、药品和日用化学品的添加成分,市场需求高,有着较高的开发利用价值。从动植物中提取香料产物存在来源少、含量低和分离困难等缺点,化学合成香料又存在着安全隐患和污染问题,很难满足市场需求。因此,研究与开发生产天然产物香料的微生物来补充或代替原有的传统提取和化学合成方法具有重要的理论意义和潜在的应用价值。酵母菌作为代谢工程菌株的一类,细胞内具有更好表达异源蛋白的细胞结构和翻译后修饰机制。文章总结了有关对酵母菌进行代谢改造生产萜类、芳香族类及脂肪族类香料化合物的具体实例和研究进展,包括所涉及的宿主菌株、关键酶、代谢途径、改造策略以及发酵条件优化等,并在最后讨论了酵母代谢工程改造生产天然产物香料目前所面临的问题和未来的发展方向。     

白藜芦醇制备方法的研究进展

综述了白藜芦醇的制备方法,其中包括植物提取法、生物技术法以及化学合成法,全面介绍了现代提取技术在白藜芦醇提取中的应用。同时对基因重组技术、细胞培养技术在白藜芦醇制备方面的应用作了系统阐述,并对其应用前景进行了评价。     

膜工艺提取猫豆左旋多巴的研究

针对传统工艺存在的收率低、有毒试剂用量大、污染严重等问题,研究了膜技术在猫豆左旋多巴提取中的应用,考察了各级膜工作过程及分离效果,探讨了膜技术工艺可行性.结果表明,猫豆提取液经过膜技术除杂、分离、浓缩三级膜过程,左旋多巴收率由传统工艺的50%提高至77.98%、纯度达到99.72%,超过国家药用要求,达到欧洲标准水平,...     

植物天然产物的微生物合成与转化

植物天然产物是一类结构复杂、性能多样的次级代谢产物,广泛应用于食品、药品、化妆品等多个领域。目前植物天然产物的主要来源依赖于从植物中提取,这种生产方式周期长且占用大量耕地。微生物细胞因其生长周期短、操作简便、环境友好、大规模发酵可控等优势而被广泛研究用以替代传统的植物提取法。目前利用微生物细胞工厂合成和转化植物天然产物已成为研究的热点,实现了萜类、黄酮、生物碱、皂苷等多种植物天然产物的合成和转化。本文分别从从头合成和生物转化的角度综述了微生物细胞工厂在植物天然产物合成中的应用,为更加系统、深入地研究植物天然产物的微生物合成与转化提供参考。     

植物细胞悬浮培养

<正>植物细胞能合成许多具有重要价值的次级代谢产物,它们可作为农药、杀虫剂、调味剂及香精等。这些产物传统上是从天然植物中直接提取,但天然植物生长周期较长,而且生长还受地域和环境因素的限制,所以采用直接提取具有较大的局限性。化学合成法已用于多种产品的生产,但是有些物质不能通过化学法合成,或虽能合成,却比较困难。植物     

代谢工程改造大肠杆菌生产L-色氨酸的研究进展

色氨酸,芳香族氨基酸之一,已被广泛应用于食品、化工、医药等行业。同传统方法酶催化、化学合成法相比,微生物法生产L-色氨酸具有生产成本低、环保和操作方便等优点。随着生物技术的快速发展,人们对大肠杆菌内色氨酸的合成机制有了更深入的了解,并实现了大肠杆菌L-色氨酸的高效生产。然而,如何突破目前大肠杆菌生产L-色氨酸的能力,降低生物合成成本是我们面临的挑战。本文对代谢工程促进大肠杆菌生产L-色氨酸的策略进行了总结。并对进一步高效生产L-色氨酸的前景进行了展望。     

Mechanism of Selective Phytotoxicity of l-3,4-Dihydroxyphenylalanine (l-Dopa) in Barnyardglass and Lettuce

l-3,4-Dihydroxyphenylalanine (l-dopa) is one of the few allelochemicals in which the phytotoxic action mechanism has been studied. Excess exogenous l-dopa suppresses root elongation in some plant species, and the inhibitory action is species-selective. The main factor of phytotoxicity of l-dopa is considered to be oxidative damage by reactive oxygen species (ROS) and/or free radical species (FRS). This study was performed to elucidate the mechanism of species-selective phytotoxicity. The involvement of ROS/FRS and polyphenol oxidase (PPO) in species-selective phytotoxicity was examined with barnyardgrass (Echinochloa crus-galli L.) and lettuce (Lactuca sativa L.), tolerant and susceptible species, respectively. Lipid peroxidation and melanin accumulation correlated with growth inhibition by L-dopa. Antioxidants, ascorbic acid and α-tocopherol, decreased lipid peroxidation and melanin accumulation and rescued lettuce root from growth inhibition. The oxidation of L-dopa by PPO was much greater in lettuce than in barnyardgrass. From these results, the phytotoxicity of L-dopa is considered due to the oxidative damage caused by ROS/FRS generated from the melanin synthesis pathway. PPO activity might be involved in the mechanism of species-selective phytotoxicity between barnyardgrass and lettuce.     

低碳经济与化肥生产的CO_2减排技术

碳酸氢铵是我国50年前独创的化肥品种。从热力学角度论证了采用合成氨厂的NH3脱除火电厂烟气中CO2制造碳酸氢铵的技术可能性;介绍了增加现代减排理念的尿素-碳铵联合生产新工艺的基本思路和原则流程;研究了电厂烟气制碳酸氢铵的原料配比、原始物料点、压力、温度和原则流程,结果表明:在化肥固碳新技术中,回收电厂烟气中CO2制造碳酸氢铵可列为首选方案。     

Optimal synthesis of compression refrigeration system using a novel MINLP approach

The optimal design of a compression refrigeration system (CRS) with multiple temperature levels is very important to chemical process industries and also represents considerable challenges in process systems engineering. In this paper, a general methodology for the optimal synthesis of the CRS, which simultaneously integrates CRS and Heat Exchanger Networks (HEN) to minimize the total compressor shaft work consumption based on an MINLP model, has been proposed. The major contribution of this method is in addressing the optimal design of refrigeration cycle with variable refrigeration temperature levels. The method can be used to make major decisions in the CRS design, such as the number of levels, temperature levels, and heat transfer duties. The performance of the developed methodology has been illustrated with a case study of an ethylene CRS in an industrial ethylene plant, and the optimal solution has been examined by rigorous simulations in Aspen Plus to verify its feasibility and consistency.     

Process design and economic optimization for the indirect synthesis of dimethyl carbonate from urea and methanol

Much attention has been paid for the synthesis of dimethyl carbonate(DMC) by urea indirect alcoholysis method, which had not been actually industrialized by now. The rigorous full process model was then necessary to optimize the process with heat integration. In this paper, a full process was designed and optimized for the DMC synthesis by urea indirect alcoholysis method based on Aspen Plus software.The technological analysis was developed to find how the process was influenced by the three main recycled materials of methanol, 1,2-propylene glycol(PG) and mixture of DMC–methanol. Simultaneously,the thermal optimization was taken into account for energy saving and the optimized process was proposed with heat integration. Moreover, the economic evaluation was implemented for the optimized process with total annualized cost(TAC) and cost of product(COP) according to the plant investment and operations. It was found that the 11.6% decrease in TAC was obtained for the optimized process compared to the original designed process. The COP analysis showed that the process was economically efficient for the production of DMC from urea and methanol.     

Flow-Sheeting-Programme für die Prozeßsimulation

Flowsheeting systems for process simulation. Simulation of process plants with flowsheeting systems has been state of the art in chemical plant design and in the chemical industry for many years. Modern computers now permit steady state simulation of complex chemical plants with sufficient accuracy. This paper outlines the different approaches to steady state process simulation, names the advantages and disadvantages, and gives an outlook on further developments. Process optimization, process integration, and process synthesis will be discussed. The integration of different programs, e.g. the connection between flowsheeting systems and computer-aided design (CAD) will be described. An advance in user friendliness will be reached by latest developments in the field of personal computers and workstations and by database management systems.     

Conifer-Derived Metallic Nanoparticles: Green Synthesis and Biological Applications

The use of metallic nanoparticles in engineering and biomedicine disciplines has gained considerable attention. Scientists are exploring new synthesis protocols of these substances considering their small size and lucrative antimicrobial potential. Among the most economical techniques of synthesis of metallic nanoparticles via chemical routes, which includes the use of chemicals as metal reducing agents, is considered to generate nanoparticles possessing toxicity and biological risk. This limitation of chemically synthesized nanoparticles has engendered the exploration for the ecofriendly synthesis process. Biological or green synthesis approaches have emerged as an effective solution to address the limitations of conventionally synthesized nanoparticles. Nanoparticles synthesized via biological entities obtained from plant extracts exhibit superior effect in comparison to chemical methods. Recently, conifer extracts have been found to be effective in synthesizing metallic nanoparticles through a highly regulated process. The current review highlights the importance of conifers and its extracts in synthesis of metallic nanoparticles. It also discusses the different applications of the conifer extract mediated metallic nanoparticles.     

对应用壳牌煤气化工艺的工厂配置和设计的建议

介绍了壳牌煤气化工艺(SCGP)的特点以及在中国已建和拟建的SCGP装置概况。根据产品气的用途和工厂规模的不同,对采用该工艺用于发电或生产合成氨、甲醇、氢气、液体燃料等化工产品的工厂的工艺流程配置与设计提出了建议,分析了装置能力的影响因素,提出了降低壳牌煤气化装置投资费用的策略。     

对大型合成氨装置"以煤顶气"改造工程的认识

以辽河化肥厂大型合成氨装置制气部分工艺改造工程为例,论述了“以煤顶气”对我国天然气化工发展的积极意义,认为改造工程为我国合成氨行业解决天然气原料不足的问题提出了解决方法,有利于提高天然气制合成气工业生产的整体技术水平;分析了天然气一煤炭共气化工艺路线在我国的发展趋势。     

Cascade refrigeration system synthesis based on exergy analysis

Refrigeration systems are very important to chemical/petrochemical process industries because their performances are closely related to product quality, energy usage efficiency, and plant profitability. Hitherto, the optimal synthesis of a cascade refrigeration system with multiple refrigerants and multiple temperature levels presents considerable challenges and systematic studies combined with thermodynamic insights and mathematical-programming approaches in this area are still lacking. In this paper, a general methodology for the optimal synthesis of such cascade refrigeration system to maximize the energy efficiency has been developed. The exergy-temperature chart combined with the exergy analysis is presented to comprehensively analyze the thermodynamic nature of a refrigeration system, which provides a solid foundation for the conceptual design/retrofit of the complex refrigeration system. An exergy-embedded MINLP model has also been developed for the optimal synthesis of a general cascade refrigeration system. The efficacy of the developed methodology is demonstrated through a case study on the retrofit of a cascade refrigeration system for an ethylene plant.     

Technology of the Fischer-Tropsch Process

Sasol One, formerly known as South African Coal, Oil, and Gas Corp., operates a plant for the production of liquid fuels, pipeline gas, and chemical products from coal in Sasolburg in the province of the Orange Free State in South Africa. This plant started production in 1955 and today Sasol has 25 years' practical experience with the production of synthesis gas via Lurgi coal gasification and the synthesis of hydrocarbons by the Fischer-Tropsch process. In 1975 the decision was taken to build a much larger Fischer-Tropsch plant, mainly for the production of motor fuels, and this plant is at present being commissioned. The first final products from this plant will become available to the public early in the second half of 1980. The continuing increase in crude oil prices and instability on the oil supply market were the incentives for the decision in 1979 to build anther Sasol plant practically identical to Sasol Two. Construction on this Sasol Three plant is well under way and it is expected to start producing in 1982. The three plants together will bring South Africa significantly closer to its goal of independence from foreign crude oil supplies.