X射线辐照后人肝细胞、肝癌细胞存活与端粒酶活性关系的研究

利用X射线对体外培养的人肝癌细胞SMMC-7721和正常人肝细胞HL-7702进行辐照,以细胞克隆形成法测定细胞存活率,多聚酶链式反应银染端粒重复序列扩增法(Telomeric repeat amplification protocol,TRAP-PCR)检测细胞中端粒酶活性变化,探讨辐照后细胞存活与细胞中端粒酶活性变化的关系。结果表明,SMMC-7721和HL-7702细胞的存活率都随辐照剂量的增加而相应降低。在1-4Gy剂量范围内,两种细胞的端粒酶活性变化均呈剂量依赖性增强。但在1Gy、2Gy、3Gy剂量下,SMMC-7721其端粒酶活性较对照(0Gy)细胞低;当辐照剂量达4Gy时,端粒酶活性略高于对照细胞。在1-4Gy剂量范围内,HL-7702和SMMC-7721的细胞存活与端粒酶活性在变化趋势上呈负的关系

~(12)C~(6+)重离子辐照对人肝细胞、肝癌细胞端粒酶活性表达的影响

为探索碳离子束辐照对细胞中端粒酶活性的变化,利用兰州近代物理研究所重离子研究装置(Heavy ion research facility in lanzhou,HIRFL)产生的碳离子(31MeV/μ12C6+),以人肝细胞HL-7702,肝癌细胞SMMC-7721为实验对象,用不同剂量1Gy、2Gy、3Gy、4Gy的重离子分别对两种细胞进行照射,用多聚酶链式反应-银染端粒重复序列扩增法(PCR-telomeric repeat amplification protocol,TRAP-PCR)银染端粒重复序列扩增法检测不同剂量下细胞端粒酶活性的变化。结果显示,人肝细胞HL-7702自身没有端粒酶活性,经1Gy辐照后也没有端粒酶活性,在2和3Gy处出现端粒酶活性,4Gy处端粒酶活性又消失。肝癌细胞SMMC-7721在1～3Gy处随着剂量的增大端粒酶活性升高,在4Gy处又开始下降;在1～3Gy处随着时间的推移端粒酶活性随着时间而加强(p<0.05)。分析得知,重离子辐射可以诱导人肝细胞产生端粒酶活性,也可以改变肝癌细胞的端粒酶活性。端粒酶参与细胞受辐照后DNA单链损伤的修复;辐照后DNA双链断裂导致端粒酶活性减弱。本实验使重离子在辐照治疗中的优势得以体现

Electrohydrodynamic direct-writing ZnO nanofibers for device applications

Interest towards adapting and developing nanofiber technology for device applications has been expanded in recent years. Here, we describe the use of electrohydrodynamic direct-writing (EDW) for the precise deposition of orderly functional nanofibers as relevant device architectures. Individual ZnO nanofibers can be obtained and assembled into complex patterns via EDW and subsequent thermal treatment. Grid arrays consisting of ZnO nanofibers were fabricated on a flat silicon substrate by controlling the trajectory of substrate. Furthermore, the precise deposition of ZnO nanofibers on three-dimensional silicon substrates including microbeams and pillars was demonstrated, illustrating the integration capability with MEMS structures and device platforms. A single ZnO nanofiber field-effect transistor was also fabricated and characterized. Our results show promise for EDW as a potential method to fabricate micro/nanodevices, especially electronics in nanoscale. ? 2013 Elsevier B.V

北方风沙区生态修复的科学原理、工程实践和恢复效果

北方风沙区位于欧亚草原的东部,是我国生态环境最为脆弱的地区之一,其在北方生态安全屏障和丝绸之路经济带建设中具有十分重要的战略地位。在国家一系列生态保育工程的支持下,该地区的生态环境得到明显改善。但是,由于受人类活动和全球气候变化的影响,该地区仍然面临着严峻的环境压力。在中国科学院科技服务网络计划(STS计划)等项目支持下,开展了北方风沙区土地沙化成因及退化土地空间分布研究,集成了北方风沙区重点脆弱区生态恢复的理论和技术体系,以内蒙古中部的阴山北麓地区、内蒙古浑善达克沙地和蒙辽交界的科尔沁沙地为重点研究区域,进行了高效人工草地建植、天然草地恢复和管理、沙化草地治理等相关工程技术的示范,开展生态恢复模式的效果跟踪监测和生态效益评估,确定生态恢复技术和模式的技术参数和指标,明确不同集成技术与模式在北方风沙区的适用区域和范围,为技术模式的推广应用提供科学依据。通过上述研究,可以为中央和地方政府制定生态系统管理和退化生态系统恢复政策、建立我国北方生态安全屏障提供决策依据,为生态修复产业提供技术指南,为相关研究提供全面系统的基础数据支撑

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