高超声速平板边界层流动显示的试验研究

本文在高超声速脉冲式风洞内对基于纳米示踪的平面激光散射技术(nano-based planar laser scattering, NPLS)的应用进行了探索, 并在此基础上对平板边界层流动结构的精细测量进行了研究. 试验来流Ma=7.3, 总压4.8 MPa, 总温680 K. 通过时序的分析和调试, 对各分系统实现了高精度的同步控制; 定量的粒子注入及混合, 实现了粒子的均匀撒播, 对主流获得了均匀的显示效果; 对于边界层流动, 获得了精细的瞬态流动结构图像, 显示了层流到湍流的转捩过程, 并分析了其时空演化特性.     

Experimental study on supersonic film cooling on the surface of a blunt body in hypersonic flow

The experimental study focuses on the heat flux on a double cone blunt body in the presence of tangential-slot super- sonic injection into hypersonic flow. The tests are conducted in a contoured axisymmetric nozzle with Mach numbers of 7.3 and 8.1, and the total temperature is about 900 K. The injection Mach number is 3.2, and total temperature is 300 K. A constant voltage circuit is developed to supply the temperature detectors instead of the normally used constant current circuit. The schlieren photographs are presented additionally to visualize the flow and help analyze the pressure relationship between the cooling flow and the main flow. The dependence of the film-cooling effectiveness on flow parameters, i.e. the blow ratio, the convective Mach number, and the attack angle, is determined. A semi-empirical formula is tested by the present data, and is improved for a better correlation.     

X射线致HeLa细胞损伤过程中NADPH氧化酶的作用

以HeLa细胞为实验材料， 探讨了NADPH氧化酶在X射线诱导细胞损伤过程中的作用。 结果显示， 12 Gy X射线辐照后细胞内活性氧(ROS)明显增加， 在用NADPH氧化酶抑制剂处理后再辐照， 则细胞内ROS降低到未辐照水平； 同时辐照后NADPH 氧化酶细胞质亚基p47phox 在细胞质积聚并和细胞膜亚基 gp91phox 结合； Western blotting检测结果显示， NADPH 氧化酶的关键亚基 gp91phox 的表达量明显增加。 以上结果说明， NADPH氧化酶可以被X射线激活， 由其介导产生的ROS在X射线诱导HeLa细胞损伤过程中扮演重要角色。 To investigate the role of NADPH oxidase in HeLa cell lesion induced by X ray irradiation, the change of cell survival was detected with MTT assay， reactive oxygen species (ROS) was measured by fluorospectrophotometer. Immunostaining and confocal laser scanning microscopy was employed to detect the co localization of two subunit of NADPH oxidase, p47phox and gp91phox in the cell. Western blotting was used to detect the expression of gp91phox before and after X ray irradiation. After X ray irradiation， intra cellular level of ROS increased obviously. But the increase could be blocked by diphenyleneiodonium (DPI)， an inhibitor of NADPH oxidase. Meanwhile， cytosolic subunit p47phox moved to membrane and co localizated with gp91phox after irradiation. Moreover, the results also show that gp91phox increased sharply after 12 Gy X ray irradiation. Therefore， NADPH oxidase mediated production of ROS plays an important role in HeLa cell lesion induced by X ray.     

二维高超声速后台阶表面传热特性实验研究

高超声速后台阶流动是大气层内高速飞行器发动机设计、表面热防护以及高超声速拦截器红外成像窗口气动光学效应校正等诸多先进高超声速技术研发过程中所涉及的一类基础流动问题. 研究高超声速后台阶流动特性对有效提升飞行器综合性能, 进一步掌握高超声速流动机理具有重大基础 意义. 本文以二维高超声速后台阶流动为研究对象, 在KD-01高超声速激波风洞中测量了二维后台阶模型表面传热系数和表面静压, 并将实测台阶下游表面传热系数分布同采用高超声速边界层理论所得估计值进行了比较. 为进一步验证实验结果, 使用NPLS技术测量了其中一种实验状态下台阶周围流动结构. 研究发现, 对于二维高超声速后台阶流动, 台阶下游表面传热分布受台阶处边界层外缘流动特性的直接影响; 在台阶下游分离区和再附区内, 气体黏性占主导作用; 在台阶下游远场区域, 边界层流动特性趋同于平板边界层; 下游边界层基本结构取决于台阶处边界层相对厚度. 对高超声速后台阶流动, 若使用数值模拟方法研究气动热问题, 应当使用湍流模型.     

带喷流超声速光学头罩流场气动光学畸变试验研究

超声速光学头罩在大气层内飞行时, 需要在光学窗口表面顺来流方向进行喷流冷却, 致使窗口上方流场更为复杂. 目标光线穿过窗口上方流场, 受到激波、膨胀波、混合层、湍流边界层等流场结构引起的变密度场影响而产生波前畸变, 导致成像出现偏移、抖动、模糊等气动光学效应. 本文对马赫数3.8来流条件下有无喷流时超声速光学头罩流场引起的气动光学波前畸变进行了试验研究. 基于纳米示踪的平面激光散射技术, 首先对流场图像进行密度校准获得高时空分辨率密度场, 然后采用光线追迹法计算得到波长532 nm平面光波垂直于光学窗口穿过流场后的光程差(optical path difference, OPD)分布, 并对窗口上方近壁区有无喷流状态的流场结构引起的 OPD分布进行了研究. 发现无喷流时, 流场结构相对较为简单, 窗口上方有较长的回流区和层流区, 而有喷流时窗口上方出现复杂的剪切层、混合层及湍流边界层, 流动很快就转捩为湍流结构, 其引起的气动光学畸变要明显高于无喷流状态. 无喷流状态相隔5 μs的流场引起的光程差均方根值分别为0.0348 和0.0356 μm, 有喷流状态的光程差均方根值分别为0.0462 和0.0485 μm. 关键词： 超声速 喷流 气动光学 光程差     

集簇性DNA损伤在辐射研究中的进展

高LET重离子引起的集簇性DNA损伤会造成细胞突变、 癌变和凋亡。 促进肿瘤细胞凋亡一直是治愈肿瘤的出发点, 所以集簇性DNA损伤已经成为放射生物学领域研究的热点问题。 由于其提取和检测方法多样, 但并没有一个详细和完整的方案对集簇性DNA损伤进行透彻分析。 综述了集簇性DNA损伤的特点和详细讨论了集簇性DNA损伤最新研究进展, 简介了集簇性DNA损伤的研究方法, 以期为集簇性DNA损伤在放疗中的研究提供一些参考。 Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in deteil in this paper.     

重离子束治疗肿瘤临床研究

文章综述了重离子束在物理学、生物学、临床治疗等方面的优势,以及在放射生物学方面的基础实验研究内容。分析总结了国内外重离子束辐照治疗肿瘤的临床研究结果。其中,日本已接受治疗了约6 000 名不同类型的肿瘤患者,并取得较高的局部控制率和生存率;德国在头颈部肿瘤临床治疗方面取得了巨大的成功;在兰州重离子研究装置(HIRFL) 肿瘤治疗终端上,中国科学院近代物理研究所联合甘肃省肿瘤医院及兰州军区总医院对肿瘤患者的重离子治疗已进入临床试验阶段。甘肃省肿瘤医院治疗结果显示:43 例患者通过影像学检查评价疗效,客观有效率(CR+PR)为71.4%,主要急性放射损伤为1-2 级皮肤反应(红斑形成和脱皮),发生率为61.9%,治疗1 个月后随访结果显示重离子束(12C6+)对深部肿瘤具有较好的局部控制作用,且无严重不良反应发生。This article reviews the advantages of heavy ion in physical, biological and clinical aspects, discusses the radio-biological basis of experiment research, and summarizes clinical results of heavy ion beam treatment on tumor at home and abroad. Japan has accepted and treated about 6000 cancer patients of different types with high local control rates and survival ones. Germany has achieved great success in head and neck tumor clinical treatment. Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS), Tumor Hospital of Gansu Province and Lanzhou General Hospital of PLA have begun clinical trial on heavy ion treatment of deep-seated tumors after the shallow-seated tumor therapy has been done at HIRFL (Heavy Ion Research Facility in Lanzhou). The treatment results of Tumor Hospital of Gansu Province show that the objective response rate (CR+PR) is 71.4% and the rate of 1-2 levels radiation injury to skin reactions (erythema and desquamation) is 61.9% when we evaluate the 43 patients by means of maging. The results of case follow-up after treatment in 1 month indicate that the deep-seated tumor therapy with heavy ion beam has high local control rates without severe adverse effect.     

低剂量连续辐射引起的小鼠免疫系统的变化

为了评估低剂量X射线连续辐射对BALB/c小鼠健康机体免疫系统的影响， 实验采用X射线全身连续照射BALB/c小鼠， 照射第一天剂量为0.07 Gy， 剂量率0.2 Gy/min， 之后每天照射0.08 Gy， 共照射12 d， 累积剂量1.03 Gy， 照射后24和48 h取血、胸腺和脾脏。 流式细胞仪检测免疫细胞周期和凋亡的变化， 胸腺和脾脏指数用重量法获取。 实验结果表明， 小鼠胸腺细胞的周期在照射后24 h被阻滞在G2/M期； 外周血淋巴和胸腺细胞周期48 h被阻滞在 G0/G1期， 细胞凋亡比例在照射后两个时间点都显著增加； 脾脏淋巴细胞周期24 h被阻滞在 G0/G1期， 48 h被阻滞在 S期， 细胞凋亡比例在24和48 h显著减少； 脾脏指数在照射后48 h显著减少。 故低剂量X射线连续全身照射BALB/c小鼠可激活免疫细胞不同的周期监测点， 引起免疫细胞凋亡比例发生变化， 造成一定的辐射损伤， 且这种影响随着免疫器官的不同而不同。 For estimating the effect of low doses X ray continual irradiation to immunity system of mouse， BALB/c mice were continually irradiated to 1.03 Gy by X rays at a dose rate of 0.2 Gy/min in 13 d. At 24 or 48 h after irradiation， the immunocyte cycle and apoptosis were determined by flow cytometry， and the thymus and spleen weights were measured too. The results showed that the cycle of thymocyte were arrested in G2/M at 24 h， the number of peripheral blood lymphocytes and thymocytes in G0/G1 phase at 48 h was up and the percentage of apoptosis had a significance increase in both of time points； the cycle of spleen lymphocytes was delayed in G0/G1 at 24 h， in S phase at 48 h， the apoptosis had a significance decrase at 24 and 48 h； spleen index declined significantly at 48 h. The results suggested that low doses continual X ray whole body irradiation could activate different cell cycle checkpoints， and result in some changes of apoptosis and some damages to immunocytes. The continual X ray irradiation affects the organs differently， it might provide experiment basis for radioprotection.     

正常及骨关节炎软骨细胞黏弹性研究

采用前交叉韧带切断术造骨关节炎(OA)动物模型，并采用微管吸吮技术和标准线性 黏弹性固体模型研究正常及OA软骨细胞的黏弹性特性. 实验研究表明：OA软骨明显退变， 大体评分及Mankin's评分均明显高于正常软骨. 正常软骨细胞直径与OA软骨细胞直径的差异无显 著意义，而正常软骨细胞与OA软骨细胞的黏弹性特性存在明显差异，正常软骨 细胞的平衡模量E , 瞬间模量E0及表观黏性 明显高于OA软骨细胞. 除正常软骨细胞平衡模量E 仅与细胞直径有微弱 相关性且具有统计学意义外，其余黏弹性参数均与细胞直径以及其 直径和微管直径比率无相关性.     

P53及其相关蛋白对X射线照射肝癌细胞周期的调节

X射线照射人肝癌细胞HepG2， 照射后细胞存活随照射剂量增大明显下降。 流式细胞术分析， 不同剂量组照射后24 h均发生G2期阻滞。 照射后不同时间组的细胞周期分布也有不同， 照射后12 h， 有显著的S期延迟。 Western Blot 显示照射后24 h P53， MDM2， P21蛋白表达上升， 并有时间效应: P53在照射后24 h之内始终维持较高表达, MDM2和P21分别在照射后6和12 h的表达最高。 X射线照射通过影响P53及其相关蛋白的表达影响细胞周期。 HepG2 cells were irradiated with X ray at the doses of 0, 1.0, 2.0, 4.0 or 8.0 Gy and separately maintained in DMEM at 37 ℃ for 0, 6, 12 or 24 h. Colony forming assay showed that cell survival decreased with the irradiation dose increasing. Cell cycle was detected by FACS, the arrest of S phase was found after 12 h irradiation and arrest of G2 phase took place at 24 h after all irradiation doses, which suggested that cell cycle distribution was different in groups gathered after different maintaining time. The results of Western blotting showed that the expression of P53, MDM2 and P21 increased more after irradiation than the control. The expression of P53 remained high at 24 h after irradiation, while the levels of MDM2 or P21 arrived at the highest at 6 h or 12 h after irradiation respectively. The expressions of P21 after irradiation were in corresponding with the cell cycle distribution in the groups of different maintaining time. In conclusion, irradiation change the distribution of cell cycle by effecting the expression of P53 and its related proteins.