The efficiency of remanufacturing in a dynamic input–output model

For industrialised economy of ourdays, remanufacturing represents perhaps the largest unexploited resource and opportunity for realising a greater growth of the economy in an environmental-conscious manner. The aim of this paper is to investigate of the impact of remanufacturing in the economy from an economic-efficiency point of view. In static context this phenomenon was analysed in the literature. We use the multi-sector input–output framework in a dynamic context to study intra-period relationships of the sectors of economy. We extend the classical dynamic input–output model taking into consideration the activity of remanufacturing .We try to answer the question, whether the remanufacturing/reuse increases the growth possibility of an economy. We expose a sufficient condition concerning the effectivity of an economy with remanufacturing. By this evaluation we analyse a possible sustainable development of the economy on the basis of the product recovery management of industries.     

A representation model for the solving-time distribution of a set of design tasks in new product development (NPD)

Given the potential risks of new product development projects (NPD), the characteristics of the design tasks solving-time distributions are critical for their effective management. In OR we need to find what operational characteristics of design tasks may delay projects. Other researchers already identified the technological novelty, the magnitude of the design tasks, the interactions between design tasks in an NPD project, and the balancing between projects among the most important causes of the unpredictability of the design tasks lead times in NPD projects.     

基于CPM原理和Dijkstra算法的SPM网络计划模型及性质

CPM(关键路线法)网络计划适用于分析工序间存在严格紧前关系(任意工序只能在它的所有紧前工序都结束时才能开始)的进度计划.针对工序间不存在严格紧前关系(任意工序只要其紧前工序中的一个结束它就可以开始)的进度计划,以CPM原理和Dijkstra算法为基础,提出SPM(最短路线法)网络计划以及拟机动时间概念,根据不同的建模原理,建立了两个SPM网络计划模型,并给出了其建立方法以及各模型拟机动时间的求法,分析了每个模型的性质,最后通过算例对其中的一类模型进行了验证.     

基于DEA的区域经济可持续发展能力的动态评价

在分析区域经济可持续发展问题的基础上,从区域经济竞争的角度提出区域经济可持续发展能力的评价问题.在此基础上,设计区域经济可持续发展能力的评价指标体系,利用数据包洛分析模型分析与研究不同区域之间的可持续发展能力的强弱变化,同时分析可持续发展能力强弱差异形成的原因,提出相应的解决方法.     

Anticoagulatory Substances of Bloodsucking Animals: From Hirudin to Hirudin Mimetics

Bloodsucking animals contain substances in their saliva that specifically interfere with the blood clotting system. These substances are mainly low molecular weight proteins with a molecular mass of between 4 and 50 kDa. Some have become accessible in large quantities with the help of genetic engineering, and as a result their structures and structure—activity relationships have been studied and clinically tested. In the light of what is known about the mode of action of these natural products at the molecular level, new compounds with possible therapeutic effect can be derived. In the last ten years this approach has been tested with the proteinase inhibitor hirudin, obtained from medicinal leeches, and with the thrombin/hirudin complex. The serine protease thrombin plays a central role in the complex pathway of the blood clotting process and its pathophysiological effect finally results in thrombosis. The selectivity of the formation of complexes from hirudin and thrombin lies in the bivalent interaction of the inhibitor with the active site of the enzyme as well as with a substrate recognition site outside of the active site, the so-called fibrin-(ogen) binding site (FBS). The knowledge of this mode of action enabled the synthesis of bifunctional thrombin inhibitors based on hirudin peptides. Hirudin and hirudin mimetics in vivo have been shown to be highly potent anticoagulants for the treatment of arterial and venous thrombosis.     

环保型汽油清净剂的研制及性能测试

以聚异丁烯基丁二酰亚胺和脲基氨基甲酸酯化合物为复合清净分散剂、多羟基醚类化合物为协同增效剂，研制了环保型汽油清净剂，通过试验确定了各组分的配比。对汽油清净剂进行了性能测试，如模拟试验、铜片腐蚀性能测试和辛烷值测试等。该汽油清净剂对发动机燃油吸入系统有良好的清洗和保洁功能，达到了降低尾气排放和节省燃油的效果。     

Trends in trace element determinations in environmental and food matrices: Conclusions of the workshop

The improvement and development of analytical techniques for the determination of trace elements in environmental and food matrices are one of the main challenges of analytical chemists nowadays. The need for a good quality control of these determinations has led the Measurements and Testing Programme (BCR) to organize series of intercomparisons and to produce certified reference materials (CRM's) for improving the quality of environmental and food matrices. At this stage, it was deemed necessary to discuss the research which should be undertaken to further improve the state of the art of trace element determinations and to develop new methodologies. A workshop on Trends in Trace Element Determinations in Environmental and Food Matrices has therefore been held in Thessaloniki in October 1994 which allowed to identify the research needs and make some recommendations based on round-table discussions. This paper gives a summary of the conclusions of the discussions. An outline of the programme along with the panel of experts participating in this workshop is given in the appendix.     

Chemistry and Biology of Taxol

One can view plants as a reference library of compounds waiting to be searched by a chemist who is looking for a particular property. Taxol, a complex polyoxygenated diterpene isolated from the Pacific Yew, Taxus brevifolia, was discovered during extensive screening of plant materials for antineoplastic agents during the late 1960s. Over the last two decades, interest in and research related to taxol has slowly grown to the point that the popular press now seems poised to scoop each new development. What was once an obscure compound, of interest only to the most masochistic of synthetic chemists and an equally small number of cellular biologists, has become one of the few organic compounds, which, like benzene and aspirin, is recognizable by name to the average citizen. In parallel, the scientific study of taxol has blossomed. Physicians are currently studying its effects on nearly every known neoplasm. Biologists are using taxol to study the mechanisms of cell function by observing the effects of its interactions with the cellular skeletal systems. Synthetic chemists, absorbed by the molecule's unique and sensitive structure and functionality, are exploring seemingly every available pathway for its synthesis. Indeed, the demand for taxol has risen so in the last five years that alternative sources to the extraction of T. brevifolia are being vigorously pursued. Because of the rapidly expanding scope of research in the multifaceted study of taxol, those who are interested in the field may find acquisition of a reasonable base of knowledge an arduous task. For this reason, this account attempts to bring together, for the first time, in a cogent overview the chemistry and biology of this unique molecule.