TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢...TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢化锆和氢化钇在不同条件下对反应堆功率的影响。计算结果表明:改变金属氢化物慢化剂的氢含量和温度参数时,堆芯径向功率峰因子的变化趋势决定了功率不均匀系数的变化趋势;慢化剂的氢含量和温度参数的改变会导致堆芯热中子分布发生变化,进而影响反应堆功率分布,低能热中子占中子群份额越高,堆芯径向功率峰因子越小;慢化剂周围的CO2气体环境导致氢损失速率较小,对反应堆功率分布的影响很小;两种慢化剂呈正温度效应,氢化钇的温度系数比氢化锆的温度系数小,且以氢化钇为慢化剂的反应堆keff更高。The TOPAZ-II reactor is a micro-space reactor that uses solid metal hydride as the moderator, with zirconium hydride being the commonly used moderator material. In recent years, the reduced manufacturing cost of yttrium has led to yttrium hydride gradually becoming a new choice of moderator material for the TOPAZ-II reactor. The MCNP program was used to calculate the power distribution of the TOPAZ-II reactor and research the influence of zirconium hydride and yttrium hydride on the reactor power under different conditions. The calculation results show that the trend of the variation in radial power peak factor determines the trend of the variation in power inhomogeneous coefficient when changing the hydrogen content and temperature parameters of the metal hydride moderator. Changes in hydrogen content and temperature parameters of the moderator can cause changes in the thermal neutron distribution in the core, thereby affecting the reactor power distribution. The higher the proportion of low-energy thermal neutrons in the neutron group, the smaller the radial power peak factor in reaction core. The CO2 gas environment surrounding the moderator causes a lower rate of hydrogen loss, resulting in minimal impact on the reactor power distribution. Both moderators exhibit positive temperature effects, with the temperature coefficient of hydrogenated yttrium being smaller than that of hydrogenated zirconium, and the keff of the reactor with hydrogenated yttrium as the moderator is higher.展开更多
文摘TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢化锆和氢化钇在不同条件下对反应堆功率的影响。计算结果表明:改变金属氢化物慢化剂的氢含量和温度参数时,堆芯径向功率峰因子的变化趋势决定了功率不均匀系数的变化趋势;慢化剂的氢含量和温度参数的改变会导致堆芯热中子分布发生变化,进而影响反应堆功率分布,低能热中子占中子群份额越高,堆芯径向功率峰因子越小;慢化剂周围的CO2气体环境导致氢损失速率较小,对反应堆功率分布的影响很小;两种慢化剂呈正温度效应,氢化钇的温度系数比氢化锆的温度系数小,且以氢化钇为慢化剂的反应堆keff更高。The TOPAZ-II reactor is a micro-space reactor that uses solid metal hydride as the moderator, with zirconium hydride being the commonly used moderator material. In recent years, the reduced manufacturing cost of yttrium has led to yttrium hydride gradually becoming a new choice of moderator material for the TOPAZ-II reactor. The MCNP program was used to calculate the power distribution of the TOPAZ-II reactor and research the influence of zirconium hydride and yttrium hydride on the reactor power under different conditions. The calculation results show that the trend of the variation in radial power peak factor determines the trend of the variation in power inhomogeneous coefficient when changing the hydrogen content and temperature parameters of the metal hydride moderator. Changes in hydrogen content and temperature parameters of the moderator can cause changes in the thermal neutron distribution in the core, thereby affecting the reactor power distribution. The higher the proportion of low-energy thermal neutrons in the neutron group, the smaller the radial power peak factor in reaction core. The CO2 gas environment surrounding the moderator causes a lower rate of hydrogen loss, resulting in minimal impact on the reactor power distribution. Both moderators exhibit positive temperature effects, with the temperature coefficient of hydrogenated yttrium being smaller than that of hydrogenated zirconium, and the keff of the reactor with hydrogenated yttrium as the moderator is higher.
文摘目的研究血管内皮细胞在冠状动脉疾病中的作用,着重阐明转录因子叉头框蛋白O3a(forkhead box O3a,FOXO3a)调控靶标基因表达和可变剪接在血管内皮细胞损伤中的作用。方法通过在人血管内皮细胞系中过表达FOXO3a,利用转录组技术获得转录组数据。分析FOXO3a调控的潜在靶标基因的表达水平和可变剪接模式,以及这些基因的功能。结果FOXO3a过表达的HUVEC细胞中,与对照组比较,419个基因差异表达。基因本体论(gene ontology,GO)和京都基因与基因组百科全书(Kyoto encyclopedia of genes and genomes,KEGG)分析结果显示,上调基因富集在炎性信号通路,下调基因富集在代谢通路。基于转录组数据进行可变剪切分析,发现1784个可变剪切事件的模式在FOXO3a过表达组和对照组间发生显著差异。GO和KEGG分析结果显示,差异可变剪切基因富集在细胞凋亡相关通路。结论FOXO3a通过调控免疫炎症、脂类代谢和细胞凋亡相关基因的表达和可变剪接,影响血管内皮细胞凋亡,可能影响冠心病的发生。
