Use of biosurfactant in the removal of oil from contaminated sandy soil

The effectiveness of cell‐free rhamnolipid biosurfactant, derived from the culture medium at the end of fermentation was investigated for the removal of two different kinds of oil from contaminated sandy soils. The crude cultivation medium, containing 13.2 g L^?1 of rhamnolipids, had a surface tension, interfacial tension and critical micellar concentration of 30 mN m^?1, 2 mN m^?1 and 60 mg L^?1, respectively. The evaluation of biosurfactant in the culture medium (BM) and oil concentrations in the removal of oil from different contaminated sandy soil was performed using a statistical experimental design tool. Oil in sandy soil, containing predominantly aromatic or paraffinic hydrocarbons (5 to 10% w/w), was removed by as much as 91 and 78%, respectively, in the presence of reduced amounts of BM (6.3 to 7.9 g L^?1). The progress of oil removal was monitored for 101 days and results indicated that removal efficiency in sandy soil with aromatic characteristics was relatively stable over the entire period. Based on these studies, it is concluded that use of a BM was effective in reducing oil concentrations in contaminated sandy soil. Copyright © 2007 Society of Chemical Industry     

平衡电负性与不对称烯烃亲电加成规律探讨

根据电负性平均化原理提出了有机分子中原子平衡电负性及其计算公式,用平衡电负性讨论了烯烃加成反应的定位规律.     

A method for solving the minimization of the maximum number of open stacks problem within a cutting process

In this paper, the problem of minimizing the maximum number of open stacks around a saw machine is addressed. A new heuristic and a branch-and-bound based exact method for the problem are presented. Computational tests comparing the new approach with other algorithms previously suggested in the literature were carried out.     

SAM AND XPS STUDIES ON SURFACE SEGREGATION OF SUBSTRATE ELEMENTS IN Au-Ni-KOVAR ALLOY SYSTEM

The surface segregation of substrate elements through the Au layer in the Au-Ni-Kovar sys- tem specimens heated at 250—350℃ for 0.5—1.5 h has been studied by SAM and XPS. Visual evidence of the mechanism for Ni and Co surface segregation of the complicated sys- tem has been given,i.e.Ni and Co penetrated the gold layer mainly by grain boundary diffu- sion and then covered the Au layer by surface diffusion.The strdy results of the chemical states of surface segregation elements not only indicate that oxygen adsorption and oxidation reaction are the driving force for the surface segregation of Ni and Co,but also show that the above segregation can result in water absorption on surfaces.     

Enrichment of omega3 fatty acids from Tyulka oil by supercritical CO2 extraction

BACKGROUND: Supercritical CO₂ enrichment of omega3 essential fatty acids (FAs) from Tyulka oil, using a batch process was investigated. Fractional factorial design was applied to evaluate the effects of the five process parameters: pressure (20.26 to 25.33 MPa); temperature (40 to 50 °C); packing fraction (0.5 to 0.7); modifier fraction (2 to 5%); and dynamic time (15 to 25 min), and their binary interactions on the enrichment of extracted omega3 FAs. By employing experimental design and analysis of variance, the variables were evaluated according to the significance of their effect on the yield of extracted omega3. RESULTS: The experimental results confirmed that pressure and dynamic time were the most important factors affecting enrichment of omega3. The amount of modifier in the feed also showed an increasing effect on the response. The binary interaction effects were investigated, and are discussed in detail. CONCLUSION: Optimum conditions were found at 25.33 MPa, 46.65 °C, packing fraction 0.50, modifier 5% and dynamic time 25 min, improving the enrichment of omega3 FAs up to 2.9 times. Copyright © 2009 Society of Chemical Industry     

Solar module using dye-sensitized solar cells with a polymer electrolyte

Dye-sensitized TiO₂ solar cells assembled with a polymer electrolyte were investigated, aiming at the construction of an 8 V solar module. The individual solar cells were assembled with 4.5 cm² active area and were characterized under outdoor conditions, exhibiting an average efficiency of 0.9% per cell (at 12:00 noon). The solar module was built by connecting 13 cells in series. The integrated average daily power was estimated to be 183 mW. The present paper discusses the performance of the individual cells and the module.     

生产工况对SJ8000鼓风机振动影响的分析

旋转机械中转子振动是最常见的故障之一。文章主要分析了SJ8000鼓风机在生产工艺过程发生变化时所引起的振动，特别是工艺过程中，当水份、燃剂变化出现平面拉沟、待料、铺不平等现象时对风机振动的影响。最后从理论上分析原因，用于指导生产。     

现场总线和以太网在步进炉系统改造中的应用

文中介绍了西门子Profibus—DP总线和IndustrialEthemet在包钢无缝钢管厂步进炉自动控翩系统升级改造中的应用实例。S7—300可编程序控制器通过DP接口将6SE70SIMOVERT变频器和分布式I／O站联入Profibus—DP网。从而实现了对步进炉设备简单、稳定、精确的自动控制，同时通过CP343—1通讯模板将S7—300联入IndustrialEt}Iemet。直接实现步进炉区域基础级设备与二级网络以及过程级的数据交换。     

包钢薄板厂冷轧工作辊剥落失效分析

对包钢薄板厂5Cr锻钢冷轧工作辊连续发生的剥落事故进行分析，指出了裂纹是导致剥落的根本原因，而轧辊的材质、磨削工艺、检测手段是产生剥落的影响因素，同时针对所存在的问题在配辊管理、磨削制度、检测制度三方面提出了技术改进措施。