500kV直流断路器快速机械开关典型故障特性及可靠性提升方法研究

直流断路器是构建柔性直流电网不可或缺的关键设备。快速机械开关是直流断路器中承载电流、实现快速分合闸、耐受分闸恢复电压的核心组件，其结构复杂、动作速度快、电气应力严酷、可靠性要求高，因而设计研制难度大，任一环节出现问题均会影响直流断路器乃至柔直电网的安全可靠运行。然而，目前快速机械开关由于存在设计选型不合理、工艺管控不严格、试验考核不完善等问题，导致在实际工程应用中故障率较高。针对已应用于张北柔性直流电网试验示范工程的500 kV直流断路器，分析了直流断路器研制、调试、运行过程中快速机械开关典型故障的特性及原因。在此基础上，围绕快速机械开关典型故障从设计选型、生产制造、试验考核等方面入手，有针对性地提出可靠性提升措施，为500 kV直流断路器快速机械开关设计研制和运维检修提供了指导和依据

All-trans retinoic acid( ATRA) inhibit proliferation of colon cancer cell lines by extracellular regulated protein kinases 1 and 2 (ERK1/2) signal pathway

目的:探讨全反式维甲酸(All-TrAnS rETInOIC ACId,ATrA)是否通过作用Erk1/2信号通路抑制结肠癌细胞增殖。方法:MTT法检测ATrA对结肠癌细胞株的增殖作用,rT-PCr及WESTErn blOT法检测ATrA处理的lS174T细胞中MEk1/2/Erk1/2的表达水平。流式细胞仪测定经ATrA与Pd98059(MEk1/2的特异性抑制剂)联合处理后的lS174T细胞的凋亡水平。结果:MTT生长曲线显示ATrA能抑制结肠癌lS174T细胞株增殖,rT-PCr及WESTErn blOT结果表明ATrA可以提高Erk MrnA及蛋白的表达水平,促进Erk磷酸化。Pd98059与ATrA联用,部分降低结肠癌细胞P-Erk表达,但增强ATrA诱导结肠癌细胞凋亡作用。结论:ATrA可以抑制结肠癌细胞增殖,其对肿瘤的诱导凋亡作用可能是通过包含MEk/Erk信号途径在内的多条信号通路进行的。Objective: To explore whether all-trans retinoic acid( ATRA) inhibits proliferation of colon cancer cell by acting ERK1 /2 signal pathway.Methods: ATRA on the proliferation of colon cancer cell lines were detected by MTT assay,RT-PCR and Western blot assay were used to detect MEK1 /2 / ERK1 /2 expression levels of LS174T cells treated by ATRA.LS174T cells apoptosis levels were measured by flow cytometry after combined treatment of ATRA and PD98059( MEK1 /2 specific inhibitor).Results: MTT growth curve showed that ATRA could inhibit the proliferation of colon cancer cell line LS174T.RT-PCR and Western blot results showed that ATRA could increase expression levels of ERK mRNA and protein,and could promote ERK phosphorylation.Combination of PD98059 and ATRA lowered some p-ERK expressions in colon cancer cells,but meanwhile enhanced ATRA-induced apoptosis.Conclusion: ATRA can inhibit proliferation of colon cancer cell,and its induction of apoptosis of tumor may be conducted by multiple signal pathways,including MEK / ERK.厦门市科技计划项目(No.3502Z20124051)资

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies