The absence and application of stable carbon isotopic fractionation during the reductive dechlorination of polychlorinated biphenyls

A bacterial enrichment culture (specific to doubly flanked chlorine removal) reductively dechlorinated 2,3,4,5-tetrachlorobiphenyl (2,3,4,5-CB) to 2,3,5-trichlorobiphenyl (2,3,5-CB) in aqueous media. Approximately 90% conversion to 2,3,5-CB occurred after 90 days, with no other products formed. The delta13C values of 2,3,4,5-CB and 2,3,5-CB were relatively constant over the course of the reaction, indicating a very small or no isotope effect. In addition, compound-specific delta13C analysis performed for every congener in three different lots of Aroclor 1268 showed an intrinsic isotopic trend of decreasing 13C abundance with increasing chlorine content, similar to observations in other commercial mixtures of polychlorinated biphenyls (PCBs). The results of this laboratory study suggest that microbial reductive dechlorination of PCBs in contaminated sediments will create congeners with more depleted delta13C values than native PCBs of similar chlorination. Such information may provide additional evidence for the occurrence of this process and aid in further understanding the biogeochemistry of these compounds.     

Experimental study of a novel hybrid constructed wetland for water reuse and its application in Southern China

A new type of hybrid constructed wetland (CW), consisting of both vertical-baffled flow wetland (VBFW) and horizontal subsurface flow wetland (HSFW), has been deployed in Southern China to naturally accelerate the removal of organic matter and nitrogen. The hybrid CW system is characterised by a combination of continuous baffled flow vertical wetland and 'S' pattern horizontal subsurface flow wetland with natural aeration ditches to increase the concentration of dissolved oxygen in the HSFW bed. An internal circulatory system from the HSFW effluent back to the VBFW may optionally be operated to enhance the biological denitrification effect. Cyperus alternifolius is the main macrophyte in the wetland bed. The performance of the hybrid CW was studied with a pilot-scale system and three full-scale systems for municipal sewage treatment in Southern China. The results suggest that this new hybrid CW can achieve removal efficiencies of chemical oxygen demand, suspended solids, ammonia nitrogen, total nitrogen, and total phosphorus of better than 83.6, 95.0, 71.7, 64.5 and 68.1% respectively, with a specific wetland bed area of 0.70-0.93 m(2) PE(-1). The mean effluent concentrations of these parameters would meet the regulatory discharge limits for wastewater treatment systems (GB18918, 2002) and reuse in the context of agricultural irrigation solutions in China.     

Three－Dimensional Numerical Simulation of Natural Convection Heat Transfer in an Inclined Cylindrical Annulus

Ｔｈｒｅｅ－ＤｉｍｅｎｓｉｏｎａｌＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａｎＩｎｃｌｉｎｅｄＣｙｌｉｎｄｒｉｃａｌＡｎｎｕｌｕｓＪ．Ｇ．ｗｅｉ；Ｗ．Ｑ．Ｔａｏ（ＳｃｈｏｏｌｏｆＥｎｅｒ...     

Discussion on the Network Method for Calculating Radiant Interchange Within an Enclosure

ＤｉｓｃｕｓｓｉｏｎｏｎｔｈｅＮｅｔｗｏｒｋＭｅｔｈｏｄｆｏｒＣａｌｃｕｌａｔｉｎｇＲａｄｉａｎｔＩｎｔｅｒｃｈａｎｇｅＷｉｔｈｉｎａｎＥｎｃｌｏｓｕｒｅ￥Ｈ．Ｊ．Ｋａｎｇ；Ｗ．Ｑ．Ｔａｏ（ＳｃｈｏｏｌｏｆＥｎｅｒｇｙａｎｄＰｏｗｅｒＥｎｇｉｎｅｅｒ...     

浪漫烛光

跳跃的火苗，透过阿拉伯通花银环映出室内异域风情，在海浪般的线条上优雅燃烧，温柔释放浪漫分子。     

Oxidation of diazinon by anodic Fenton treatment

Anodic Fenton treatment (AFT) is a new technology that has several advantages over classic Fenton treatment and electrochemical Fenton treatment. The oxidation of diazinon by AFT using different electrolytes has been investigated. NaCl, KCl and Na2SO4 show similar effects on the extent and rate of oxidation, and the data can be fitted quite well by the AFT kinetics model. Use of NaNO3 as the electrolyte causes low-efficiency electrolysis and a subsequent low oxidation rate for diazinon. The NaCl concentration level in the anodic half-cell and the concentration ratio between the two half-cells is optimized at 0.04M and 4:1 (cathodic/anodic), respectively. The activation energy of diazinon oxidation by anodic Fenton treatment is estimated to be 12.6 +/- 0.6 kJ mol(-1), which is less than half of that for aqueous chlorine treatment. Diazoxon is the intermediary oxidation product. The oxidation of diazinon as a formulated product has also been investigated. Its dissipation kinetics can also be fitted quite well by the AFT model. Compared with the oxidation of pure diazinon, the oxidation rate of formulated diazinon is much lower, an indication that many formulation ingredients compete with diazinon for reaction with the hydroxyl radical.     

让电脑应用发挥到极限——联想天骄E3000X宽带关联电脑

今年。联想在整机市场上可谓动作十分频繁,有2999元的乡镇电脑,也有旗舰型的K9000,最近又正式收购了IBM的PC业务,这些都显示出了联想在台式机市场上的强大实力。最近,联想又推出了一款天骄E3000X宽带关联电脑,与K9000最大的不同是前者着重于与众不同的功能,而K9000则是豪华的硬件配置。     

Socket 754平台廉价解决方案——捷波智尊K8TTP＋Athlon 64 2800＋套装

对于广大的AMD Fans来说，Athlon 64处理器无疑是目前最受欢迎的处理器之一，而采用90nm的Sockot 939接口的Athlon 64处理器更是热销，市场基本上处于脱销状态。相比较来说，Sockot 754接口的Athlon 64处理器有些受人冷落，因为其只内置了单通道内存控制嚣，不过对于资金有限的AMD Fans来说，尤其是学生用户，还是具有不小的诱惑。最近，捷波推出智尊KST7P+Athlon 64 2800+，学生凭学生证只需1599元。     

Intel平台的整合新宠——双敏URC410NS主板

前段时间由于Intel的产能问题,其主要精力都放在移动平台及中高端芯片组,因此在低端芯片组方面,Intel几乎不闻不问。正是由于Intel的这一态度,众多第三方芯片组开始抢占低端平台市场,其中VIA和ATI表现得最为抢眼。ATI推出的RC410系列芯片组不单单在硬件特性上领先于915芯片组,而且价格更低,开始频繁冲击市场,而双敏电子也第一时间推出了 URC410NS主板。     

A bulk electrolysis Raman spectroelectrochemical cell using a rotating electrode

A fast bulk electrolysis Raman spectroelectrochemical cell is described. The cell employs a large-area platinum gauze and disk assembly which can be rotated at speeds up to 5,000 rpm. The complete electrolysis of a 5-mL solution can be achieved in less than 6 min using a 2,000 rpm rotation rate. The resonance Raman spectrum of (TPP*+)Cu(II) was collected in situ in this cell.