In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what...In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Con- gress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a ＂hydrogen＂ economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors.展开更多
Colloidal dispersions of nanoparticles are known as ＇nanofluids＇. Such engineered fluids offer the potential for enhancing heat transfer, particularly boiling heat transfer, while avoiding the drawbacks （e.g., eros...Colloidal dispersions of nanoparticles are known as ＇nanofluids＇. Such engineered fluids offer the potential for enhancing heat transfer, particularly boiling heat transfer, while avoiding the drawbacks （e.g., erosion, settling, clogging） that hindered the use of particle-laden fluids in the past. At Massachusetts Institute of Technology （MIT）, the authors have been studying the heat transfer characteristics of nanofluids for the past five years, with the goal of evaluating their benefits for and applicability to nuclear power systems （e.g., primary coolant, safety systems, severe accident mitigation strategies）. This paper summarizes the MIT research in this area with particular emphasis to boiling behavior, including, prominently, the Critical Heat Flux limit and quenching phenomena.展开更多
目的挖掘特立帕肽、阿巴洛肽的药物不良事件(adverse drug event,ADE)信号,为临床安全用药及合理选药提供参考。方法提取FAERS数据库特立帕肽2004年第1季度—2021年第3季度、阿巴洛肽自2017年上市至2021年第3季度的ADE报告数据,采用报...目的挖掘特立帕肽、阿巴洛肽的药物不良事件(adverse drug event,ADE)信号,为临床安全用药及合理选药提供参考。方法提取FAERS数据库特立帕肽2004年第1季度—2021年第3季度、阿巴洛肽自2017年上市至2021年第3季度的ADE报告数据,采用报告比值比法(reporting odds ratio,ROR)和比例报告比法(proportional report ratio,PRR)进行数据挖掘,分析两药相关ADE报告并统计报告人群的性别、年龄、严重ADE等基本信息。结果排除各类损伤、中毒及操作并发症,各类手术及医疗操作,以及产品问题和社会问题等与药物无关的信号后,得到特立帕肽相关的ADE报告有88474例,有效信号为600个,信号涉及22个系统器官;阿巴洛肽相关的ADE报告有12286例,有效信号为137个,累及系统器官17个。按发生频次排序,2种药物发生最多的ADE分别是头晕(4896例)和头痛(1485例);按信号强度排序,特立帕肽报告的尿氨基端肽升高(ROR:135.867)和阿巴洛肽报告的血清I型原胶原蛋白氨基端前肽降低(ROR:881.625)居于首位,说明书中均未提及。两药ADE信号均集中于各类肌肉骨骼和结缔组织疾病,全身性疾病及给药部位各种反应。结论特立帕肽与阿巴洛肽上市以来的应用总体较为安全,引起的常见不良反应大多较为轻微,但治疗期间仍需特别注意罕见不良反应的发生情况并定期检测血钙、血尿酸等实验室指标,提防骨骼系统ADE。展开更多
Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in...Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in the community （residence time）, and the interaction between these two variables. We tested these effects using data on the effects of American bullfrog Lithobates catesbeianus invasion on native frog communities in 65 permanent lentic waters on islands in the Zhoushan Archipel- ago, China. We examined variation in native frog abundance and species richness in relation to features of the American bullfrog invasion, habitat disturbance, characteristics of the water body and fish communities and the presence of red swamp crayfish. Bullfrog invaded sites had lower native frog density and species richness, higher submerged vegetation cover and greater fre- quency of repairs to the water body than did non-invaded sites. The minimum adequate general linear mixed models showed that both native frog density and species richness were negatively related to post-metamorphosis bullfrog density, and that native frog species richness was also positively related to the vegetation cover. There was no effect on either native frog density or species richness of residence time or its interaction with bullfrog density, or of the abundance of bullfrog tadpoles. The results suggested that post-metamorphosis bullfrogs had impacts on native frog communities in the islands, and that the extents of these impacts are proportional to post-metamorphosis bullfrog density展开更多
文摘In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Con- gress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a ＂hydrogen＂ economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors.
文摘Colloidal dispersions of nanoparticles are known as ＇nanofluids＇. Such engineered fluids offer the potential for enhancing heat transfer, particularly boiling heat transfer, while avoiding the drawbacks （e.g., erosion, settling, clogging） that hindered the use of particle-laden fluids in the past. At Massachusetts Institute of Technology （MIT）, the authors have been studying the heat transfer characteristics of nanofluids for the past five years, with the goal of evaluating their benefits for and applicability to nuclear power systems （e.g., primary coolant, safety systems, severe accident mitigation strategies）. This paper summarizes the MIT research in this area with particular emphasis to boiling behavior, including, prominently, the Critical Heat Flux limit and quenching phenomena.
基金Acknowledgements We thank Feng XU and Yanping WANG for helping a part of field works and Richard Duncan for comments on the manuscript. This work was supported by a grant from National Science foundation （No. 30870312） and by a grant from the ＂973＂ program （No. 2007CB411600）.
文摘Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in the community （residence time）, and the interaction between these two variables. We tested these effects using data on the effects of American bullfrog Lithobates catesbeianus invasion on native frog communities in 65 permanent lentic waters on islands in the Zhoushan Archipel- ago, China. We examined variation in native frog abundance and species richness in relation to features of the American bullfrog invasion, habitat disturbance, characteristics of the water body and fish communities and the presence of red swamp crayfish. Bullfrog invaded sites had lower native frog density and species richness, higher submerged vegetation cover and greater fre- quency of repairs to the water body than did non-invaded sites. The minimum adequate general linear mixed models showed that both native frog density and species richness were negatively related to post-metamorphosis bullfrog density, and that native frog species richness was also positively related to the vegetation cover. There was no effect on either native frog density or species richness of residence time or its interaction with bullfrog density, or of the abundance of bullfrog tadpoles. The results suggested that post-metamorphosis bullfrogs had impacts on native frog communities in the islands, and that the extents of these impacts are proportional to post-metamorphosis bullfrog density
