Very low Beta superconducting spoke cavity is one of the key challenges for the China-ADS project. In this paper, a new structure of 3βλ/2 spoke cavity is first studied in detail. Its RF and mechanical properties ar...Very low Beta superconducting spoke cavity is one of the key challenges for the China-ADS project. In this paper, a new structure of 3βλ/2 spoke cavity is first studied in detail. Its RF and mechanical properties are simulated using CST-MWS and ANSYS, and compared with the traditional βλ/2 spoke structure.展开更多
Hierarchical Fe-Beta obtained by hydrothermal synthesis exhibited higher low-temperature NH_3-SCR activity than conventional Fe-Beta. In order to identify the main factors leading to the difference in catalytic activi...Hierarchical Fe-Beta obtained by hydrothermal synthesis exhibited higher low-temperature NH_3-SCR activity than conventional Fe-Beta. In order to identify the main factors leading to the difference in catalytic activity, we investigated the pore structure, acidity and Fe sites of the hierarchical Fe-Beta and conventional Fe-Beta. The enhanced activity of hierarchical Fe-Beta was mainly due to the increase of the quantity of active Fe species. NH_3-TPD and DRIFTS results of NH_3 adsorption clearly verified that hierarchical Fe-Beta had more Lewis acid sites, which is beneficial to the adsorption and activation of NH_3. The H_2-TPR, UV–vis DRS, and EPR results confirmed that the hierarchical Fe-Beta had more isolated active Fe species, which may be associated with that the hierarchical structure introduced more structural defects as ion-exchange sites. Based on the analysis of kinetics experiments and the abovementioned characterizations, it can be concluded that the improvement of NH_3-SCR activity was not due to an intrinsic effect of the specific structural characteristics, but was related to more Fe active sites and better dispersion of Fe species in the hierarchical Fe-Beta.展开更多
A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-l...A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.展开更多
To demonstrate the ability of the Nativis signal transduction technology (Butters et al. 2014) to modulate the expression of algae mRNA and protein, we tested if we can alter specific enzyme levels in Chlamydomonas re...To demonstrate the ability of the Nativis signal transduction technology (Butters et al. 2014) to modulate the expression of algae mRNA and protein, we tested if we can alter specific enzyme levels in Chlamydomonas reinhardtii. We inhibited the synthesis of the enzyme tryptophan synthase beta subunit (MAA7) by applying the signal derived from a published siRNA (Zhao et al. 2009). With lower levels of MAA7, Chlamydomonas reinhardtii can grow in the presence of the prodrug 5-Fluoroindole (5-FI), because less 5-Fluoroin-dole can be converted to the toxic 5-Fluoro-L-tryptophan (5-FT). We find a 24% (±5%) increase of growth with the signal versus no signal. To see if that effect was due to the reduction of the amount of mRNA encoding MAA7, we used Real-Time Quantitative PCR (RT-QPCR) to measure the levels of MAA7 mRNA. To normalize the MAA7 mRNA level, we compared them to the levels of a mRNA that is not affected by the signal (G protein beta subunit-like polypeptide, Cblp). Two conditions increase the effectiveness of the signal. One can either treat the cell cultures during the logarithmic growth phase (starting the cultures at density of 0.104 OD at 750 nm). Or one can treat the cultures at a later stage of the logarithmic growth, but treating them for a longer time (8.7% versus 3.5% of the culture time). Under these conditions we found around a 50% decrease in the mRNA levels for MAA7. Treating the cultures at the earlier growth phase or at a later growth phase is less effective, with only a 20% effect.展开更多
针对国内测量85Kr探测下限较高的现状,本文通过探测其衰变产生的β射线,设计并优化探测系统的本底和探测效率,实现对85Kr极低放射性浓度的测量。在探测器设计中,采用国产正比计数管作为4π主探测器,辅以铅铜屏蔽,以塑料闪烁体作为反符...针对国内测量85Kr探测下限较高的现状,本文通过探测其衰变产生的β射线,设计并优化探测系统的本底和探测效率,实现对85Kr极低放射性浓度的测量。在探测器设计中,采用国产正比计数管作为4π主探测器,辅以铅铜屏蔽,以塑料闪烁体作为反符合探测器。通过Geant4模拟研究正比计数管的探测效率,分析了其尺寸、工作气压对探测下限的影响,提出了优化方案。模拟结果表明,最佳的正比计数管参数为半径30 mm、长度100 mm,并在压强大于1 atm的条件下可有效提高探测效率至92%以上。塑料闪烁体反符合效率达90.29%,铅铜屏蔽厚度优化为外层8 cm、内层2 cm,屏蔽效率达99.5%。根据优化得到的主探测器的探测效率和探测系统的本底,计算出理论探测下限可达16.08 m Bq/m~3,比国内正比计数管的探测下限180 m Bq/m~3降低一个数量级。本研究为开发一种成本低、结构简单、性能可靠的^(85)Kr实时监测系统提供了重要的模拟参考和理论依据。展开更多
目的研究β-葡聚糖对单核细胞释放动脉粥样硬化致病因子[肿瘤坏死因子α(TNF-α)、白细胞介素18(IL-8)和白细胞介素12(IL-12)]的影响。方法用密度梯度离心法分离健康志愿者新鲜血液中的单核细胞,使用佛波醇酯(PMA)诱导单核细胞分化为巨...目的研究β-葡聚糖对单核细胞释放动脉粥样硬化致病因子[肿瘤坏死因子α(TNF-α)、白细胞介素18(IL-8)和白细胞介素12(IL-12)]的影响。方法用密度梯度离心法分离健康志愿者新鲜血液中的单核细胞,使用佛波醇酯(PMA)诱导单核细胞分化为巨噬细胞,进一步利用氧化低密度脂蛋白(ox-LDL)诱导巨噬细胞为泡沫细胞,将实验分为无药对照组、ox-LDL组、颗粒性β-葡聚糖(WGP)组和WGP+ox-LDL组,提取总RNA,扩增TNF-α、IL-8和IL-12 c DNA,并采用酶联免疫吸附试验(ELISA)测定细胞上清液中的浓度。结果与无药对照组比较,ox-LDL诱导单核细胞TNF-α、IL-8和IL-12蛋白水平的表达显著升高(P<0.05),而WGP可以显著抑制ox-LDL诱导的上述细胞因子在蛋白水平和TNF-α、IL-8在mRNA水平的表达(P<0.05)。结论β-葡聚糖可能通过抑制单核细胞促炎因子的分泌减缓动脉粥样硬化形成。展开更多
基金Supported by Strategic Priority Research Program of CAS(XDA03020600)
文摘Very low Beta superconducting spoke cavity is one of the key challenges for the China-ADS project. In this paper, a new structure of 3βλ/2 spoke cavity is first studied in detail. Its RF and mechanical properties are simulated using CST-MWS and ANSYS, and compared with the traditional βλ/2 spoke structure.
基金financial supports from the National Natural Science Foundation of China (Nos. 51822811, 21637005)the National Key R&D Program of China (Nos. 2017YFC0212502, 2017YFC0211101)the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment, CAS (No. CERAE201806)
文摘Hierarchical Fe-Beta obtained by hydrothermal synthesis exhibited higher low-temperature NH_3-SCR activity than conventional Fe-Beta. In order to identify the main factors leading to the difference in catalytic activity, we investigated the pore structure, acidity and Fe sites of the hierarchical Fe-Beta and conventional Fe-Beta. The enhanced activity of hierarchical Fe-Beta was mainly due to the increase of the quantity of active Fe species. NH_3-TPD and DRIFTS results of NH_3 adsorption clearly verified that hierarchical Fe-Beta had more Lewis acid sites, which is beneficial to the adsorption and activation of NH_3. The H_2-TPR, UV–vis DRS, and EPR results confirmed that the hierarchical Fe-Beta had more isolated active Fe species, which may be associated with that the hierarchical structure introduced more structural defects as ion-exchange sites. Based on the analysis of kinetics experiments and the abovementioned characterizations, it can be concluded that the improvement of NH_3-SCR activity was not due to an intrinsic effect of the specific structural characteristics, but was related to more Fe active sites and better dispersion of Fe species in the hierarchical Fe-Beta.
基金supported by National Natural Science Foundation of China under grant No.59374160.
文摘A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.
文摘To demonstrate the ability of the Nativis signal transduction technology (Butters et al. 2014) to modulate the expression of algae mRNA and protein, we tested if we can alter specific enzyme levels in Chlamydomonas reinhardtii. We inhibited the synthesis of the enzyme tryptophan synthase beta subunit (MAA7) by applying the signal derived from a published siRNA (Zhao et al. 2009). With lower levels of MAA7, Chlamydomonas reinhardtii can grow in the presence of the prodrug 5-Fluoroindole (5-FI), because less 5-Fluoroin-dole can be converted to the toxic 5-Fluoro-L-tryptophan (5-FT). We find a 24% (±5%) increase of growth with the signal versus no signal. To see if that effect was due to the reduction of the amount of mRNA encoding MAA7, we used Real-Time Quantitative PCR (RT-QPCR) to measure the levels of MAA7 mRNA. To normalize the MAA7 mRNA level, we compared them to the levels of a mRNA that is not affected by the signal (G protein beta subunit-like polypeptide, Cblp). Two conditions increase the effectiveness of the signal. One can either treat the cell cultures during the logarithmic growth phase (starting the cultures at density of 0.104 OD at 750 nm). Or one can treat the cultures at a later stage of the logarithmic growth, but treating them for a longer time (8.7% versus 3.5% of the culture time). Under these conditions we found around a 50% decrease in the mRNA levels for MAA7. Treating the cultures at the earlier growth phase or at a later growth phase is less effective, with only a 20% effect.
文摘针对国内测量85Kr探测下限较高的现状,本文通过探测其衰变产生的β射线,设计并优化探测系统的本底和探测效率,实现对85Kr极低放射性浓度的测量。在探测器设计中,采用国产正比计数管作为4π主探测器,辅以铅铜屏蔽,以塑料闪烁体作为反符合探测器。通过Geant4模拟研究正比计数管的探测效率,分析了其尺寸、工作气压对探测下限的影响,提出了优化方案。模拟结果表明,最佳的正比计数管参数为半径30 mm、长度100 mm,并在压强大于1 atm的条件下可有效提高探测效率至92%以上。塑料闪烁体反符合效率达90.29%,铅铜屏蔽厚度优化为外层8 cm、内层2 cm,屏蔽效率达99.5%。根据优化得到的主探测器的探测效率和探测系统的本底,计算出理论探测下限可达16.08 m Bq/m~3,比国内正比计数管的探测下限180 m Bq/m~3降低一个数量级。本研究为开发一种成本低、结构简单、性能可靠的^(85)Kr实时监测系统提供了重要的模拟参考和理论依据。
文摘目的研究β-葡聚糖对单核细胞释放动脉粥样硬化致病因子[肿瘤坏死因子α(TNF-α)、白细胞介素18(IL-8)和白细胞介素12(IL-12)]的影响。方法用密度梯度离心法分离健康志愿者新鲜血液中的单核细胞,使用佛波醇酯(PMA)诱导单核细胞分化为巨噬细胞,进一步利用氧化低密度脂蛋白(ox-LDL)诱导巨噬细胞为泡沫细胞,将实验分为无药对照组、ox-LDL组、颗粒性β-葡聚糖(WGP)组和WGP+ox-LDL组,提取总RNA,扩增TNF-α、IL-8和IL-12 c DNA,并采用酶联免疫吸附试验(ELISA)测定细胞上清液中的浓度。结果与无药对照组比较,ox-LDL诱导单核细胞TNF-α、IL-8和IL-12蛋白水平的表达显著升高(P<0.05),而WGP可以显著抑制ox-LDL诱导的上述细胞因子在蛋白水平和TNF-α、IL-8在mRNA水平的表达(P<0.05)。结论β-葡聚糖可能通过抑制单核细胞促炎因子的分泌减缓动脉粥样硬化形成。
