Radiosensitivity to high energy iron ions is influenced by heterozygosity for Atm, Rad9 and Brca1

Loss of function of DNA repair genes has been implicated in the development of many types of cancer. In the last several years, heterozygosity leading to haploinsufficiency for proteins involved in DNA repair was shown to play a role in genomic instability and carcinogenesis after DNA damage is induced, for example by ionizing radiation. Since the effect of heterozygosity for one gene is relatively small, we hypothesize that predisposition to cancer could be a result of the additive effect of heterozygosity for two or more genes critical to pathways that control DNA damage signaling, repair or apoptosis. We investigated the role of heterozygosity for Atm, Rad9 and Brca1 on cell oncogenic transformation and cell survival induced by 1 GeV/n⁵⁶Fe ions. Our results show that cells heterozygous for both Atm and Rad9 or Atm and Brca1 have high survival rates and are more sensitive to transformation by high energy iron ions when compared with wild-type controls or cells haploinsufficient for only one of these proteins. Since mutations or polymorphisms for similar genes exist in a small percentage of the human population, we have identified a radiosensitive sub-population. This finding has several implications. First, the existence of a radiosensitive sub-population may distort the shape of the dose–response relationship. Second, it would not be ethical to put exceptionally radiosensitive individuals into a setting where they may potentially be exposed to substantial doses of radiation.     

High energy charged particle experiment – A payload proposal to KuaFu-B mission

High Energy Charged Particle Experiment (HECPE) is to measure the fluxes of MeV electrons and tens of MeV protons. The two satellites of KuaFu-B are in the same polar orbit with apogee 7.0R_E, perigee 1.8R_E. They can sweep large L values and pass through the inner and outer radiation belts. The high energy electrons and protons in the radiation belts are principal sources for failures of satellites and spacecrafts in the Earth orbits. The enhancements of the high energy electrons and protons, so-called energetic particle events, are important phenomena of the Space Weather. The energy ranges monitored by HECPE are 0.3–0.5 MeV, 0.5–1.0 MeV, 1.0–2.0 MeV, and E > 2.0 MeV for electrons, 5–10 MeV, 10–20 MeV, 20–40 MeV, and 40–80 MeV for protons.     

航空重油活塞发动机发展趋势及关键技术分析

在充分调研和分析国内外航空重油活塞发动机发展现状的基础上,通过对比几种已定型发动机和在研发动机的性能参数,分析国内外的研究热点,正视国内外研制水平的差距并剖析原因。在调研现有的航空重油活塞发动机研发技术路线基础上,提出了适合我国国情的自主研发技术路线:以高功质比、低耗油率为发展目标,探索了未来航空重油活塞发动机应使用的二冲程做功、压燃着火等技术方案。基于国内外航空活塞动力的瓶颈技术问题,分析并提炼了航空重油活塞发动机在产品化过程中涉及到的结构轻量化、高可靠性等总体设计,以及多级废气涡轮增压、燃油喷射雾化等部件级优化的关键技术,为航空重油活塞发动机的产品化提供技术保障。     

涡轮级间双涡燃烧室的出口温度分布试验

在单涡燃烧室研究的基础上,对双涡燃烧室进行出口温度分布试验研究,得到了影响出口温度分布系数(OTDF)的因素如下:①随着主流马赫数的增加,出口温度分布系数减小;②主流温度对出口温度分布影响较大,出口温度分布系数随主流温度的增加而减小;③随着余气系数的增大,出口温度分布系数都有先增大后趋于平缓或减小的过程;④不同的凹腔结构对出口温度分布系数的影响很大,综合各个试验件结果,深宽比为0.8,后体进气方式为开槽进气的双1试验件的出口温度分布系数最小.      

全环涡轮级间燃烧室性能试验

以涡轮级间燃烧室(ITB)应用于涡轴发动机为研究平台,根据ITB的应用环境,采用凹腔驻涡燃烧室作为涡轮级间燃烧室,设计加工了全环凹腔驻涡燃烧室试验件,并进行了性能试验研究.试验结果表明:该燃烧室的贫油点火边界余气系数为10.2,降低驻涡凹腔体内外压差有利于点火;与常规燃烧室相比,燃烧室的燃烧效率偏低,但燃烧效率随进口温度的升高逐步加大;燃烧室的总压恢复系数较小,进口温度对燃烧室的总压恢复系数影响不大;燃烧室出口温度场分布较好,出口温度分布系数(OTDF)随进口温度的升高而减小;随着进口温度的提高,火焰筒壁温会局部偏高,火焰筒的冷却设计需优化改进.      

机场刚性道面接缝弯沉测试的非零截距问题

采用HWD对1126个机场刚性道面板接缝进行弯沉测试,研究了机场刚性道面板接缝两侧弯沉随荷载级位变化的规律,结果表明：道面板两侧弯沉-荷载之间存在良好的线性关系;但接缝两侧弯沉-荷载回归直线在弯沉轴均存在非零截距,对于受荷板一侧此值在-136.82～＋75.23μm范围内,未受荷板一侧此值在-52.95～＋97.98μm范围内,此非零截距对于弯沉比传递系数的影响最大可达130%。分析指出弯沉-荷载曲线的非零截距为HWD车架及轮胎回弹和道面板回弹综合作用的结果,在弯沉比传递系数计算中应予以修正,提出了修正的弯沉比传递系数计算公式及根据接缝两侧弯沉-荷载回归直线斜率之比定义弯沉比传递系数的方法,可以彻底消除荷载级位对于道面传荷能力测试结果的影响。     

纵列式双旋翼重型直升机操纵系统及飞控系统方案研究

通过对纵列式双旋翼重型直升机的静稳定性和动稳定性进行理论分析,找出了影响纵列式双旋翼重型直升机最关键的迎角静不稳定和速度静不稳定问题,针对上述问题提出了相应的操纵模式,并制定了操纵系统及飞控系统的初步技术方案。     

Response of photosynthetic systems to salinity stress in the desert cyanobacterium Scytonema javanicum

The present study investigated the physiological and biochemical characteristics of Scytonema javanicum, a pioneer species isolated from desert biological crusts, under salinity stress. Pigment analysis showed that salinity decreased chlorophyll a and phycocyanin content, while low salinity increased carotenoid concentration and high salinity decreased carotenoid concentration. Salinity also inhibited CO₂ assimilation rate and photosynthetic oxygen evolution in this cyanobacterium. Chlorophyll a fluorescence transient parameters (φPo, φEo, ψO, RC/ABS, RC/CS, PI_ABS, and PI_CS) were decreased under salt stress, while dVo/dto(Mo), Vj and φDo were increased. The decrease of ETRmax and Yield and the change of chlorophyll a fluorescence transients showed that salt stress had an important influence on photosynthesis. These results indicated that the effects of salinity stress on photosynthesis in S. javanicum may depend on the inhibition of electron transport and the inactivation of the reaction centers, but this inhibition may occur in the electron transport pathway at the PSII donor and acceptor sites.     

空间重离子辐照效应评述

文章对生物、半导体、光学材料、金属、聚合物的空间重离子辐照效应的研究工作进行了评述,也阐明了深入开展重离子空间环境模型以及重离子辐照效应与演化规律的研究具有重要意义。研究表明空间环境中重离子的含量虽少,但由于其高的电离能力和穿透力,对生物、半导体、光学材料、金属、聚合物等会产生各种辐射损伤效应,导致卫星信号故障、光学器件失效、金属与聚合物性能及形貌改变,甚至影响航天员的生命安全。     

驻涡燃烧室最佳中心驻体宽度选择的数值研究

为确定驻涡燃烧室中心驻体最佳宽度,在四种来流条件下,对当量宽度为0.3～0.8范围,间隔为0.05当量宽度的中心驻体驻涡燃烧室三维黏性流场进行了冷态数值模拟.计算结果表明,当量宽度在0.65～0.70的中心驻体有利于在驻涡腔内形成低速且稳定的流动.驻体宽度增加会导致驻涡腔外侧主流气流速度提高,引起摩擦损失的加大,燃烧室出口截面处的总压损失增加.