鱼肝EROD酶活力诱导作为二噁的水生态毒理学指标

利用离体EROD法对严家湖各氧化塘鱼肝中二噁的毒性效应进行了定量测定，同时与HRGC／HRMS－MID化学分析结果和野外活体暴露鱼肝中EROD活力诱导结果进行了比较。研究发现，各氧化塘中鱼肝的离体、活体EROD测定结果与化学分析结果之间有着极好的相关性。这不仅揭示了鱼肝细胞色素P450系统以EROD酶活力诱导指示可作为二的水生态毒理学指标的可靠性和准确性，同时也表明了活体EROD和离体EROD生物监测方法两者可以相互补充，用于其他环境生物样品中二类毒物的快速筛选。

中华鳖胸腺显微和亚显微结构及其在进化上的意义

应用透射电子显微镜观察了中华鳖胸腺的显微和亚显微结构。发现中华鳖胸腺从结构上可分为皮质和髓质，皮质富含淋巴细胞，髓质富含上皮性网状细胞。在各发育期中华鳖胸腺皮质、髓质交界处和髓质区有明显的囊状胸腺小体和交错突细胞。在200g以上的成年鳖胸腺内发现有同心圆状胸腺小体。电镜下，胸腺内淋巴细胞分为大、中、小3型。上皮性网状细胞从亚显微结构上分为支持型和分泌型。胸腺囊包括细胞内囊和细胞间囊，以细胞内囊居多。部分毛细血管管腔与淋巴细胞之间出现具4层结构的血一胸腺屏障。60g左右幼鳖胸腺部分皮质区已开始出现退化。至5

The potential use of 241Am as proliferation resistant burnable poison in PWRs

This paper discusses the use of 241Am as proliferation resistant burnable poison for light water reactors. Homogeneous addition of small (as little as 0.12%) amounts of 241Am to the conventional light water reactor fuel results in significant increase in 238Pu/Pu ratio in the discharged fuel improving its proliferation resistance. Moreover, 241Am, admixed to the fuel, acts as burnable absorber allowing for substantial reduction in conventional reactivity control means without a notable fuel cycle length penalty. This is possible due to favorable characteristics of 241Am transmutation chain. The fuel cycle length penalty of introducing 241Am into the core is evaluated and discussed, as well as the impact of He production in the fuel pins and degradation of reactivity feedback coefficients. Proliferation resistance and reactivity control features related to the use of 241Am are compared to those of using 237Np, which has also been suggested as an additive to the conventional fuel in order to improve its proliferation resistance. It was found that 241Am admixture is more favorable than 237Np admixture because of the smaller fuel cycle length penalty and higher burnable poison savings. Addition of either 237Np or 241Am would provide substantial but not ultimate protection from misuse of Pu originating in the spent fuel from the commercial power reactors. Therefore, the benefits from application of the concept would have to be carefully evaluated against the additional costs and proliferation risks associated with manufacturing of 237Np or 241Am doped fuel. Although this work concerns specifically with PWRs, the conclusions could also be applied to BWRs and, to some extent, to other thermal spectrum reactor types. © 2009 Elsevier Ltd. All rights reserved.