连云港海州湾麻痹性贝类毒素中毒分析

为分析连云港地区麻痹性贝类毒素中毒特征,对连云港海州湾织纹螺进行形态鉴定,收集近年麻痹性贝类中毒资料,应用小白鼠生物测定法检测螺肉中麻痹性贝类毒素。结果连云港海州湾存有4种织纹螺,其中以半褶织纹螺含麻痹性贝类毒素量高(1.6×103μg100g螺肉),并导致连云港地区10起、银川1起麻痹性贝类中毒;1992年还发生一起由泥螺引起的麻痹性贝类中毒。中毒者均表现为下行性神经麻痹症状,重者致死。鉴于海洋污染的严重性,为保障海洋贝类的食用安全,应对贝类进行毒素等安全指标的监测。     

Effect of ammonium ion distribution on Nafion conductivity

Nafion^® conductivity in a proton exchange membrane fuel cell (PEMFC) with the fuel stream containing ammonia is mainly affected by the ammonium ion composition and operating conditions. In this study, the effect of ammonium ion distribution on Nafion conductivity was investigated for the first time. The conductivities of two kinds of contaminated membranes having uniform and non-uniform ammonium ion distributions were studied. To simulate a membrane with a well-defined ammonium ion concentration profile, three individual Nafion membranes containing known amounts of ammonium ions were physically stacked together. The uniform and non-uniform cases represented membranes having three layers with the same yN⁺H₄ or step changes in concentration, respectively. Under fuel cell operations, the conductivities of non-uniformly poisoned membranes were ca. 1.07-1.86 times larger than those of uniformly poisoned membranes, depending on humidity, contamination level, and ammonium ion distribution. Consequently, the performance prediction of a cationic-poisoned PEMFC needs to consider any concentration gradients that may exist in MEA. The liquid-phase conductivities of composite membranes were also studied and the results show that conductivity measurements performed in deionized water are not representative of what exists under fuel cell conditions due to rapid redistribution of ions in the Nafion via the liquid phase.     

泊松方程的高精度优化差分方法

本文提出了数值求解二维泊松方程的九点优化差分方法,正方形网格时达六阶精度O(h~6)。文中放弃了许多离散方法把源项局部“冻结”的处理方法,考虑了其在离散网格内的局部空间变化,分析了该项的处理对格式精度的影响。分析和计算表明,本文提供的方法具有精度高和收敛快等特点。     

非金属毒物对汽油加氢催化剂LD265的影响及处理方法

通过中国石化广州分公司几年来的生产实践,阐述了汽油加氢装置一段催化剂LD265对不同毒物的适应性能和处理方法,从而保证催化剂的运行周期和使用寿命。     

Individual Variation in Alkaloid Content of Poison Frogs of Madagascar (Mantella; Mantellidae)

Brightly colored Malagasy poison frogs, Mantella spp., sequester lipophilic, basic alkaloids from arthropod prey for their own chemical defense. Consequently, microsympatric prey diversity is expected to influence alkaloid diversity observed in poison frogs. Twenty-two specimens of three Mantella species from four localities in moist forests of southeastern Madagascar were analyzed individually via gas chromatography-mass spectrometry, revealing that they contain over 80 known alkaloids. Frogs within a locality possessed significantly similar alkaloid content and diversity, while frogs from areas that varied in disturbance, elevation, and/or species showed greater differences. Based on dietary data, the larger frog species Mantella baroni consumed more and larger prey, and showed greater diversity in skin alkaloids than significantly smaller Mantella bernhardi. Additionally, frogs from the most pristine locality had the greatest number of alkaloids, whereas individuals from the most disturbed localities had the least. In a comparison of frog alkaloid profiles over a 10- to 14-yr period, alkaloid turnover, and thus presumably alkaloid-source arthropod turnover, was high in a disturbed locality and low in the pristine primary forest locality. We demonstrate that the nonlethal transcutaneous amphibian stimulator (TAS) is effective for harvesting alkaloids from poison frogs; future studies using this device could obtain larger sample sizes without harming local frog populations.Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

碳三加氢催化剂的常见毒物

介绍了乙烯装置碳三馏分液相加氢反应及工艺,毒物是碳三液相加氢催化剂失活的重要原因之一。重点介绍了砷、硫、水、重金属对碳三催化剂运行的影响及毒物的脱除方法,控制好碳三反应器进料中的毒物,可以减缓催化剂活性下降,延长使用寿命。     

Characteristic studies of a PBI/H3PO4 high temperature membrane PEMFC under simulated reformate gases

A high temperature proton exchange membrane fuel cell is considered a solution to improve the cell performance under CO-contained hydrogen and to simplify the gas purification process of a reformate fuel cell system. In this study, polybenzimidazole-based phosphoric acid-doped fuel cells are studied under simulated reformate gases of different H₂, N₂ and CO concentrations. The experimental results show that the dilution effect of N₂ has a minor impact on the cell performance in absence of CO. However, the CO poisoning increases the charge transfer resistance and leads to a substantial performance drop. This work also reveals that increasing the operating temperature can effectively improve the CO tolerance by suppressing the Pt–CO binding reaction. In addition, the CO poisoning effect becomes more significant in diluted H₂. As a result, the CO concentration should be maintained lower than a critical level to prevent a high CO coverage on the catalyst which leads to a noteworthy voltage shut-down, especially in highly diluted H₂.     

红外吸收光谱法对季胺萃取铀过程中毒问题的研究

本工作采用红外吸收光谱法研究确定了在萃取铀浸出液时,致使季胺萃取剂严重中毒的物质是连多硫酸盐:S_4O_6~(2-),S_3O_6~(2-),S_2O_6~(2-)。本文还讨论了硫化物矿物在加压碱浸时的氧化作用以及季胺萃取剂中毒机制等问题。     

Identifying Control and Management Plane Poison Message Failure by K-Nearest Neighbor Method

Poison message failure is a mechanism that has been responsible for large-scale failures in both telecommunications and IP networks. The poison message failure can propagate in the network and cause unstable network. In this paper, we apply machine learning, data mining technique in network fault management area. We use k-nearest neighbor method to identify the poison message failure. Also we integrate the k-nearest neighbor method with message filtering approach. We also propose a “probabilistic” k-nearest neighbor method that outputs a probability distribution (rather than the identity) of the poison message. Through extensive simulations, we show that k-nearest neighbor method is very effective in identifying the responsible message type.Xiaojiang (James) Du is an assistant professor in Department of Computer Science, North Dakota State University. Dr. Du received his B.E. degree from Tsinghua University, Beijing, China in 1996, and his M.S. and Ph.D. degrees from University of Maryland, College Park in 2002 and 2003, respectively, all in Electrical Engineering. His research interests are wireless sensor networks, mobile ad hoc networks, network security and network management. Dr. Du is an associated editor of Wiley Journal of Wireless Communication and Mobile Computing. He is the program chair of Computer and Network Security Symposium of IEEE International Wireless Communication and Mobile Computing Conference (IWCMC) 2006. He is (was) a TPC member for many major IEEE conferences such as INFOCOM, ICC, GLOBECOM, IM, and NOMS.