利用HIRFL加速的重离子获得半导体器件的σ-LET曲线

表征器件单粒子敏感度的σ-LET 曲线是轨道翻转率预估的重要依据.利用兰州重离子加速器（HIRFL）加速的 35 MeV/u的36Ar离子和 15.14 MeV/u的136Xe离子得到的 32 kbit×8静态存储器（SRAM）IDT71256单粒子翻转的实验数据,用Weibull和Lognormal两种函数拟合获得了完整的σ-LET 曲线,对两种拟合结果的差别进行了讨论,并在拟合参数的基础上估算了地球同步轨道和两条太阳同步轨道辐射环境中IDT71256的翻转率.

不同LET的重离子辐射对DSB诱导的影响

利用γ射线和不同LET的碳离子辐照小鼠B16黑色素瘤细胞的脱蛋白DNA ,采用脉冲场凝胶电泳结合荧光扫描技术研究了DNA双链断裂 (DSB)与LET之间的关系。结果表明 :不同LET重离子诱导的PR都随剂量的增加而增加 ,并在超过一定的剂量之后逐渐趋于一个准阈值 :而不同LET的重离子诱导的L值都与剂量呈线性关系 ;对于诱导DSB的RBE值则随着LET的增加先呈上升趋势 ,在LET超过 10 0ke μm后下降。

不同LET碳离子对哺乳动物细胞的生物学效应

目的　研究不同传能线密度 (LET)的重离子对体外培养细胞存活率、微核率和染色体畸变的效应。方法　用集落形成法研究细胞的存活情况 ,观察统计细胞微核率和染色体结构的变化。结果　①细胞存活 :不同LET碳离子引起细胞失活效应由大到小的顺序依次为 12 5 ,2 0 0 ,70 0keV μm。②细胞微核 :相同剂量下 ,2 0 0keV μm碳离子所致微核率高于 70 0keV μm时的结果。③染色体畸变 :可看到多种染色体结构变异。结论　在本实验中 ,LET为 12 5keV μm的碳离子引起的失活效应最大 ,2 0 0keV μm碳离子引起的微核率高于 70 0keV μm碳离子引起的微核率

不同LET碳离子对V79细胞辐射敏感性的影响

以中国仓鼠肺V79细胞为材料 ,利用兰州近代物理研究所重离子研究装置 (HIRFL)产生的碳离子 ,研究了不同线性能量传递 (LET)的重离子对体外培养细胞的存活效应 ,并与γ射线的结果作了比较。结果表明 ,不同LET碳离子引起细胞失活效应由大到小的顺序依次为 12 5、2 0 0、70 0keV/μm。碳离子表现为无肩区的存活曲线 ,属单靶单击模型 ,γ射线表现为有肩区的存活曲线 ,属多靶单击模型。LET值为 12 5、2 0 0、70 0keV/μm时得到的失活截面分别为 35、12、8μm2 。当细胞存活比率为 0 .1和 0 .37,在LET为 12 5keV/μm时得到相对生物学效应 (RBE)值为1.4 7和 2 .19。

Survivin expressions in human hepatoma HepG2 cells exposed to ionizing radiation of different LET

Survivin is a member of the inhibitors of apoptosis (IAP) protein family that interferes with post-mitochondrial events including activation of caspases. To examine the regulation of survivin expression in response to irradiation with different linear energy transfer (LET), human hepatoma HepG2 cells were irradiated in vitro with X-rays and carbon ions. Cellular sensitivities to low- and high-LET radiation were determined by colony formation. Survivin expression at mRNA and protein level were measured with RT-PCR and Western blot analyses, respectively. Radiation-induced cell cycle arrest and apoptosis were investigated with flow cytometry. We found that low-LET X-rays induced dose-dependent increases in survivin expression. After exposure to high-LET carbon ions, survivin expression gradually increased from 0 to 4 Gy, and then declined at 6 Gy. More pronounced survivin expression, stronger G(2)/M phase arrest was observed after exposure to carbon ions in comparison with X-rays at doses from 0 to 4 Gy. These observations indicate that there is a differential survivin expression in response to different LET radiations and the cycle arrest mechanism may be associated with it. In addition, our data on induction of apoptosis are compatible with the assumption that survivin expression induced by low-LET X-rays radiation may play a critical role in inhibiting apoptosis. However, after irradiation with ions, an anti-apoptotic function of survivin is not evident, possibly because of the serious damage produced by densely ionizing radiation.

Biodosimetry estimate for high-LET irradiation

The purpose of this paper is to prepare for an easy and reliable biodosimeter protocol for radiation accidents involving high-linear energy transfer (LET) exposure. Human peripheral blood lymphocytes were irradiated using carbon ions (LET: 34.6 keV mu m(-1)), and the chromosome aberrations induced were analyzed using both a conventional colcemid block method and a calyculin A induced premature chromosome condensation (PCC) method. At a lower dose range (0-4 Gy), the measured dicentric (dics) and centric ring chromosomes (cRings) provided reasonable dose information. At higher doses (8 Gy), however, the frequency of dics and cRings was not suitable for dose estimation. Instead, we found that the number of Giemsa-stained drug-induced G2 prematurely condensed chromosomes (G2-PCC) can be used for dose estimation, since the total chromosome number (including fragments) was linearly correlated with radiation dose (r = 0.99). The ratio of the longest and the shortest chromosome length of the drug-induced G2-PCCs increased with radiation dose in a linear-quadratic manner (r = 0.96), which indicates that this ratio can also be used to estimate radiation doses. Obviously, it is easier to establish the dose response curve using the PCC technique than using the conventional metaphase chromosome method. It is assumed that combining the ratio of the longest and the shortest chromosome length with analysis of the total chromosome number might be a valuable tool for rapid and precise dose estimation for victims of radiation accidents.

Protective effects of melatonin against low- and high-LET irradiation

To investigate the protective effects of melatonin against high-LET ionizing radiation, V79 Chinese hamster cells were irradiated with 100 keV/mu m carbon beam. Parallel experiments were performed with 200 kV X-rays. To avoid the impact from extra solvents, melatonin was dissolved directly in culture medium. Cells were cultured in melatonin medium for 1 hr before irradiation. Cell inactivation was measured with conventional colony forming assay, medium containing 6-thioguanine was used for the selection of mutants at hprt locus, and the cell cycle was monitored by flow cytometry. Both carbon beam and X-rays induced cell inactivation, hprt gene mutation and cell cycle G2 block dose-dependently. But carbon beam showed stronger effects as indicated by all three endpoints and the relative biological effectiveness (RBE) was 3.5 for cell killing (at 10% survival level) and 2.9 for mutation induction (at 5 x 10(-5) mutants/ cell level). Melatonin showed protective effects against ionizing radiation in a dose-dependent manner. In terms of cell killing, melatonin only increased the survival level of those samples exposed to 8Gy or larger of X-rays or 6 Gy or larger of carbon beam. In the induction of hprt mutation and G2 block, melatonin reduced such effects induced by carbon beam but not by X-rays. The results suggest that melatonin reduces the direct interaction of particles with cells rather than an indirect interaction. Further studies are required to disclose the underlying mechanisms.

抑制survivin表达增强人肝癌HepG2细胞对高线性能量转移射线的辐射敏感性；Inhibiting Survivin Expression Increases The Radiosensitivity of Human Hepatoma HepG2 Cells to High-LET Radiation

探讨了肿瘤细胞中survivin的表达对高线性能量转移(LET)射线辐射敏感性的影响.根据Gen Bank提供的survivin序列,合成特异性survivin-siRNA寡核苷酸,转染人肝癌HepG2细胞,抑制survivin的表达.发现siRNA转染后诱导了HepG2细胞G2/M期阻滞,增加了自发性和辐射诱导的细胞凋亡.在高线性能量转移(LET)碳离子辐照后,siRNA转染细胞的克隆存活率明显下降.这些结果表明survivin表达是HepG2细胞产生对高LET射线辐射抗性的关键因素.

Survivin表达在高LET射线诱导细胞凋亡中作用机理的初步研究；A Preliminary Study on Action Mechanisms of Survivin Expression in Cell Apoptosis Induced by High-LET Radiation

先前的研究表明,肿瘤细胞中survivin的高表达与细胞对高传能线密度(LET)射线的辐射抗性相关。研究了survivin表达在高LET射线诱导的细胞凋亡中的作用,发现抑制survivin表达对高LETC离子辐射诱导的Bcl-2和Bax表达没有明显的影响。在高LET射线辐照中,survivin可能通过抑制caspase-3和-9活性的途径,抑制了细胞凋亡。

Inhibiting Survivin Expression Increases The Radiosensitivity of Human Hepatoma HepG2 Cells to High-LET Radiation

The influence of survivin expression on the radiosensitivity of tumor cells to high linear energy transfer (LET) radiation is investigated. Survivin-specific short-interfering RNA (siRNA) oligonucleotides were synthesized based on the survivin sequence provided by GenBank. Human hepatoma HepG2 cells were transfected with survivin-specific siRNA to inhibit its expressions. It was found that the transfection with surviving-specific siRNA increased the levels of G2/M arrest and the apoptotic rates induced by radiation in HepG2 cells. After exposure to high-LET carbon ions, a reduced clonogenic survival effect was observed in the cells treated with siRNA. These results show that survivin plays a key role in mediating the radioresistance of cells to high-LET radiation.

Inactive and mutagenic effects induced by carbon beams of different LET values in a red yeast strain

To evaluate biological action of microorganism exposed to charged particles during the long distance space exploration. Induction of inactivation and mutation in a red yeast strain Rhodotorula glutinis AY 91015 by carbon beams of different LET values (14.9-120 0 keV mu m(-1)) was investigated It was found that survival curves were exponential, and mutation curves were linear for all LET values The dependence of inactivation cross section on LET approached saturation near 120 0 keV mu m(-1) The imitation cross section saturated when LET was higher than 582 keV mu m(-1) Meanwhile, the highest RBEI for inactivation located at 120 0 key mu m(-1) and the highest RBEm for mutation was at 58.2 key mu m(-1) The experiments imply that the most efficient mutagenic part of the depth dose profile of carbon ion is at the plateau region with intermediate LET value in which energy deposited is high enough to Induce mutagenic lesions but too low to induce over kill effect in the yeast cells (C) 2010 Elsevier B V All rights reserved

不同LET辐射对健康人血淋巴细胞和肿瘤细胞的损伤效应

目的: 探讨不同LET辐射对健康人外周血淋巴细胞的遗传损伤效应；了解重离子辐射诱导人血淋巴细胞染色体畸变的特点；研究用G2期染色体畸变预测肿瘤细胞辐射敏感性的可行性。材料与方法：采用兰州近代物理研究所重离子研究装置产生的12C离子和兰州大学第一附属医院放疗科提供的X射线照射健康人外周血，用常规染色体分析技术和姊妹染色体差别染色法研究不同LET辐射对健康人血淋巴细胞中期染色体的损伤效应、高LET辐射的剂量率效应、时程效应和染色体畸变的特点；用Calyculin A诱导间期染色体凝集技术研究12C 离子对淋巴细胞G2期染色体的损伤效应。用60Coγ射线照射人卵巢癌细胞和肝癌细胞，以细胞克隆存活率和G2期染色体畸变为生物学终点，探讨用G2期染色体畸变预测肿瘤细胞辐射敏感性的可行性。 结果与结论 1. 不同LET辐射诱导‘双+环’畸变与剂量之间存在良好的线性平方关系， 12C 离子诱导的畸变在细胞间的分布不符合泊松分布； 12C离子的相对生物学效应随着LET的增大而增大；12C离子诱导染色体畸变在1－5 Gy/min的范围内不存在剂量率效应；在0－4 Gy的剂量范围内不存在时程效应，说明培养48小时后中期‘双+环’畸变能很好的反应12C离子对淋巴细胞的损伤效应。本研究可以帮助人们了解重离子的相对生物学效应，为病人健康组织的保护以及放射医师的防护提供重要的理论数据。 2. LET为34.6 keV/μm的12C离子诱导淋巴细胞G2-期染色体数目畸变与剂量之间存在良好的线性关系(r=0.99)；最长G2-PCC与最短G2-PCC的长度之比与剂量之间存在良好的线性平方关系(r2=0.96)。表明有希望用G2-期染色体畸变评估重离子的相对生物学效应和估计重离子的辐射剂量，也为合理评估空间混合辐射场中重离子辐射所占比例提供了两个潜在的指标。 3. LET为34.6 keV/μm12C 离子诱导的畸变，除大部分染色体型畸变外，还出现少量的染色单体畸变，这一现象在理论上突破了传统的认识，对重离子辐射损伤机理的认识有重要意义。这可能是由于重离子特殊的离子径迹结构诱导染色单体畸变。重离子相对生物学效应是相对于常规射线而言的，而常规射线辐照G0期淋巴细胞只产生染色体型畸变，因此这一现象的存在对重离子相对生物学效应的确定提出了新的问题。 4. γ射线诱导肿瘤细胞G2期染色体初始断裂畸变和修复24小时后残余断裂畸变都与辐射剂量有良好的相关性；肿瘤细胞克隆存活率与G2染色单体初始断裂(r=0.96)和修复24小时后残余断裂(r=0.91)都有一定的相关性，比较而言，G2染色单体初始断裂畸变能更好的反映肿瘤细胞的辐射敏感性，预示G2染色单体初始断裂畸变有希望成为肿瘤细胞辐射敏感性的预测指标。 5. 2 Gyγ射线诱导的G2-染色单体断裂畸变，有近65% 的断裂在辐射后24小时内得以修复；对G2等点染色单体断裂畸变，在辐射后24小时内只有20%左右得以修复；两类畸变的修复主要发生在辐射后2小时内。 6. 在用G2-assay法测定染色体畸变的实验中，给予较高剂量时，很难获得足够的中期细胞以供观察。用G2-assay和G2-PCC技术获得的数据都与细胞克隆存活率有一定的相关性，比较而言，后者的相关性要好一些。表明G2-PCC技术可以作为细胞存活实验和用常规染色体畸变分析放射敏感性的替代方法

An Operating Environment for the Jellybean Machine

The Jellybean Machine is a scalable MIMD concurrent processor consisting of special purpose RISC processors loosely coupled into a low latency network. I have developed an operating system to provide the supportive environment required to efficiently coordinate the collective power of the distributed processing elements. The system services are developed in detail, and may be of interest to other designers of fine grain, distributed memory processing networks.

Investigating the removal of some pharmaceutical compounds in hospital wastewater treatment plants operating in Saudi Arabia

The concentrations of 12 pharmaceutical compounds (atenolol, erythromycin, cyclophosphamide, paracetamol, bezafibrate, carbamazepine, ciprofloxacin, caffeine, clarithromycin, lidocaine, sulfamethoxazole and Nacetylsulfamethoxazol (NACS)) were investigated in the influents and effluents of two hospital wastewater treatment plants (HWWTPs) in Saudi Arabia. The majority of the target analytes were detected in the influent samples apart from bezafibrate, cyclophosphamide, and erythromycin. Caffeine and paracetamol were detected in the influent at particularly high concentrations up to 75 and 12 ug/L, respectively. High removal efficiencies of the pharmaceutical compounds were observed in both HWWTPs, with greater than 90 % removal on average. Paracetamol, sulfamethoxazole, NACS, ciprofloxacin, and caffeine were eliminated by between >95 and >99 % on average. Atenolol, carbamazepine, and clarithromycin were eliminated by >86 % on average. Of particular interest were the high removal efficiencies of carbamazepine and antibiotics that were achieved by the HWWTPs; these compounds have been reported to be relatively recalcitrant to biological treatment and are generally only partially removed. Elevated temperatures and high levels of sunlight were considered to be the main factors that enhanced the removal of these compounds.