辐射诱发细胞内活性氧增高与DNA氧化损伤研究

用60 Coγ射线照射人支气管上皮细胞 (BEP2D)。细胞内过氧化氢 (H2 O2 )和超氧阴离子(O2 · - )分别用分子探针 2’ ,7’ -二氯荧光黄双乙酸盐 (DCFH -DA)和氢化乙锭 (HE)进行标记 ,并通过流式细胞仪测定荧光产物 2’ ,7’ -二氯荧光黄 (DCF)和溴乙锭 (EB)荧光强度进行相对定量分析。DNA氧化损伤产物 8-羟基脱氧鸟嘌呤 (OH8dG)含量用高压液相色谱结合电化学方法 (HPLC-ECD)测定。结果表明 ,60Coγ射线诱发BEP2D细胞内活性氧 (ROS)水平和OH8dG含量均显著增高 ,并有良好的剂量效应关系。进一步分析显示 ,60 Coγ射线照射诱发BEP2D细胞内ROS增高与DNA氧化损伤产物OH8dG含量呈明显正相关 ,提示辐射对细胞的损伤效应可能与其诱发细胞内ROS增高及其对DNA氧化损伤机制有关     

~(60)Coγ射线照射离体人外周血诱发淋巴细胞染色体畸变与剂量的关系

在离体标准条件下,人外周血淋巴细胞受~(60)Coγ射线照射,细胞培养51～53小时,显微镜下检查记录照射后第一次有丝分裂中期的染色体畸变。实验表明,在24.4～292.8拉德范围内,剂量率为48.8拉德/分的~(60)COγ射线诱发双着丝点体和着丝点环的剂量-效应关系,可拟以二次多项式:Y=(1.28±0.22)×10~(-4)D+(4.08±0.60)×10~(-6)D~2;而在0-24.2拉德范围内,剂量率为17.5拉德/小时,双着丝点体的剂量-效应是直线关系,Y=(1.36±0.29)×10~(-4)D。     

低剂量氚β射线和~(60)Coγ射线诱发人淋巴细胞染色体畸变及相对生物效应的研究

介绍了用氚β射线和~(60)COγ射线离体照射G_0期人淋巴细胞诱发染色体畸变的剂量效应关系(剂量范围为0-0.5Gy)。实验表明:无论是氚β射线还是~(60)Coγ射线所诱发的淋巴细胞染色体畸变均以染色体型畸变为主,诱发的双着丝粒体与剂量的关系均适合以Y=a+bD模式来表示。以~(60)Coγ射线为参考辐射,以淋巴细胞染色体畸变为生物终点,测得氚的RBE值为2。     

闪烁剂量仪对宇宙射线的相对灵敏度及其对测量天然贯穿辐射水平影响的估计

本文分析了用电流法或脉冲高度积分法的闪烁剂量仪对宇宙射线的相对灵敏度K_γ/k_c(K_γ、k_c分别为仪器对γ射线和宇宙射线的刻度因子)。给出了不同K_γ/K_c值下,由大水面上响应值 R_w、宇宙射线剂量率 D_c 及其屏蔽因子μ的偏差对测量室外(或室内)天然贯穿辐射剂量 D(或 D_(?))和有效剂量当量率 H_E(或(?))的偏差影响的估计公式。对室外γ辐射剂量率D_γ=4.0×10~(-8)Gy·h~(-1),D_c=3.0×10~(-8)Gy·h~(-1),H_E=5.8×10~(-8)Sv·h(-1),μ=0.9和仪器本底R_0=0.2×10~(-8)Gy·h~(-1)情况下,在k_γ/k_c=0.8时,R_w 和 D_c 偏差为10%,其对 D 和 H_B 所致偏差分别不大于1%和2.5%;当μ的偏差为10%,其对(?)和(?)的偏差分别不大于1%和2.5%。     

一个邻近效应超导体及其超导电性

在高Tc单相Y_1BaCu_3O_(7_δ)大块超导体的实验研究中,利用仔细的DC磁化测量,第一次实验上发现了一个高T_c邻近效应超导体,并研究了它的超导电性,其临界参量用注脚a表示。这些参量为: T_(ea)=84.7K;H_(cla)(0)=15.6Oe;H_(ea)(0)=108.1Oe; H_(c2a)(0)=372.2Oe;λ(0)=2.3× 10~(-5)cm;ξ(0)=9.4×10~(-6)cm; k=2.44;γ=2.6×10~(-8)J/(cm~3·K~2);2/K_BTc=3.56; 结果表明,邻近效应超导体是一个Ⅱ类超导体,且是一个弱耦合的BCS超导体。     

BPS型TE-TE球形空腔电离室在15MeV中子场测量的修正因子

我所研制了BPS型TE-TE球形空腔电离室。本工作测量了这些电离室的基本性能。饱和特性的测量结果表明,在~(60)Co光子场中Q_B/Q_V与V~(-2)之间,关系是线性的,相关系数极接近于1,由此得出了饱和修正因子。对于15MeV中子和~(60)Co光子确定了自由空气比释动能的壁厚修正因子,各自为(0.6±0.9)·10~(-2)mm~(-1)和(0.49±0.35)·10~(-2)mm~(-1)当射线入射角度范围在0-120°范围时,室响应相对变化对于~(60)Coγ射线不大于0. 5％,而对于15 MeV中子大约为1％。还研究测定了自由空气照射电离室在光子场与中子场中柄散射的影响,测量和计算了用TE气体和空气分别作为工作气体时电离室读数之比值,结果相符。     

稀土、铀、钍苦味酸盐与喹哪啶酸氮氧化物配合物的合成与表征

研究了稀土、铀、钍苦味酸盐与喹哪啶酸氮氧化物的配合作用,合成了组成为Ln_2(Pie)_3·(ANO)_3·3H_2O(Ln=La、Pr、Nd、Sm、Eu、Gd、Er、Y;Pic为苦味酸根离子;ANO-为喹哪啶酸氮氧化物阴离子)、UO_2(ANO)_2和Th(Pic)·(ANO)_3·5H_2O的固态配合物,并对配合物的组成,红外、紫外光谱,热稳定性,X射线衍射物相分析及摩尔电导等性质进行了测试和表征。     

0.8 MeV单能中子照射洋葱萌发种子后在根尖细胞中诱发微核的相对生物效能

通过由加速器产生的0.8 MeV单能中子和60Coγ射线照射洋葱萌发种子,观察在根尖细胞中微核诱发率,从而更好地了解中子相对生物效能(RBE)。洋葱萌发种子照射单位剂量0.8 MeV单能中子和60Coγ射线后,根尖细胞中的微核诱发率分别为111±6.7(10-2Gy-1)和3.59±0.19(10-2Gy-1)。因此,以60Coγ射线为参考辐射时,0.8 MeV单能中子在洋葱根尖细胞诱发微核的相对生物效能(RBE)值为31.0±2.5。与252Cf裂变中子的RBE比较,0.8 MeV单能中子照射在洋葱根尖细胞中诱发微核的RBE值要高。     

硝酸铀酰与二苯并-24-冠-8的固态配合物的合成及性质

本文报道了硝酸铀酰与DB24C8的固态配合物的合成,测定其组成为[UO_2(NO_3)_2]_2·DB24C8·4H_2O,并对其红外光谱、紫外光谱、差热-热重分析、摩尔电导及X射线粉末衍射等性质进行了研究。     

各种自由基清除剂在γ射线辐照DNA损伤中的作用

为了对重离子辐照致DNA损伤中的自由基作用进行评估,本文利用γ射线对添加了各种自由基清除剂(甘露醇,维生素C和茶多酚)的质粒DNA进行辐照,凝胶电泳分析的结果表明,三种自由基清除剂对DNA均有很好的保护作用.在相同自由基清除剂浓度的情况下,甘露醇比维生素C具有更强的清除自由基的作用.与重离子辐照情况相比,这几种自由基清除剂对γ射线产生的自由基的清除作用更为明显.     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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Radioactivity levels in soil of salt field area,Kelambakkam,Tamilnadu,India

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer.The activity concentration for ~(232)Th,~(238)U and ~(40)K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg,and from 135.54 to 381.28 Bq/kg,respectively.The measured activity concentrations for these radionuclides were compared with world average activity of soil.The average activity concentration of ~(232)Th in the present study is 1.19 times higher than world median value while the activity of ~(238)U and ~(40)K is found to be lower. The absorbed dose rates due to these radionuclides were calculated.The average absorbed gamma dose rate due to the presence of ~(232)Th,~(238)U and ~(40)K in soil samples is 36.99 nGy·h~(-1).These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.     

Non-FDG PET imaging of brain tumors

Due to relatively high uptake of glucose in the brain cortex, the use of FDG PET imaging is greatly limited in brain tumor imaging, especially for low-grade gliomas and some metastatic tumours. More and more tracers with higher specificity were developed lately for brain tumor imaging. There are 3 main types of non-FDG PET tracers： amino acid tracers, choline tracers and nucleic acid tracers. These tracers are now widely applied in many aspects of brain tumor imaging. This article summarized the general use of non-FDG PET in different aspects of brain tumor imaging.     

基于NPL-NMC系统的γ测量子系统的建模与优化

在军控核查中,核部件的质量、丰度、年龄属性需采用无损方法进行核查,NPL-NMC系统是一套利用中子多重性测量核部件质量属性的装置,为建立完善的属性测量系统,还需在NPL-NMC系统的基础上建立γ测量子系统。本文通过设计γ测量子系统在NPL-NMC系统上的布局及对中子屏蔽的优化,使系统能对铀部件的丰度、年龄属性进行测量。模拟计算结果表明,该γ测量子系统能很好地满足军控核查对铀部件丰度、年龄属性测量的要求。     

Improvement of carbon fiber surface properties using electron beam irradiation

Carbon fiber-reinforced advance composites have been used for structural applications,mainly on account of their mechanical properties.The main factor for a good mechanical performance of carbon fiber-reinforced com- posite is the interfacial interaction between its components,which are carbon fiber and polymeric matrix.The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite.EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests.Experimental results showed that EB irradiation improved the ten- sile strength of carbon fiber samples.The maximum value in tensile strength was reached using doses of about 250 kGy.After breakage,the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated.SEM micrographs showed modifications on the carbon fiber surface.     

Measurement system for SSRF pulsed magnets

This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application pro- gram based on LabVIEW has been developed as main control unit.After the magnetic field mapping of a septum magnet prototype,it is verified that the test results accord with the results of theoretical calculation and computer simulation.     

旁路阀调节对高温气冷堆闭式布雷顿循环瞬态特性影响研究

闭式布雷顿循环是第4代高温堆核能系统的关键技术之一,其典型的动态过程是旁路阀调节。为分析这一过程,建立了循环中关键部件的动态模型,其中压气机在径向平衡模型基础上耦合了对附面层发展的预测,兼顾了计算效率与准确性;换热部件模型基于双曲型守恒律方程,对工质的热物性和参数的快速变化有较好的适应性。在此基础上根据回路的质量守恒和压力平衡原则将各部件的模型耦合,建立了系统的动态模型。由于旁路阀调节是氦气透平发电系统主要的功率快速调节手段,瞬态效应较为显著,以模块式高温气冷堆（HTR-10GT）旁路阀开启后的过渡过程作为算例,分析了主要循环参数的响应特性,并通过分析,给出了降低输出功率的机制。计算结果表明：系统的容积惯性对旁路阀调节的响应速度影响较大,而阀门的开度则决定了系统在末态的输出功率;回热器的温度冲击现象可能发生在调节过程中,但可通过两旁路阀联动的方式缓解;反应堆出口温度变化幅度很小,因此反应堆模型的准确程度对结果基本无影响。     

CEFR 100%额定功率运行汽轮机发电能力分析

中国实验快堆(CEFR)首次100%额定功率发电运行中,实际电功率较设计值相差较多。为判断影响机组实际发电能力的主要原因,以现场采集的运行数据和汽轮机厂商提供的设计资料为基础,进行了相应的计算分析。对汽轮机内效率进行修正,绘制汽轮机近似热力过程曲线,并通过实测的各段抽汽压力,在热力过程曲线上获得抽汽焓值;利用换热器的能量守恒和流量守恒的基本方程进行除氧器和各加热器的热平衡计算,获得各段抽汽的流量;利用汽轮机的功率计算方程,得到汽轮机发电功率的计算值。通过计算值与实际值的比较分析,得出主蒸汽参数不达标是影响CEFR汽轮机发电能力的主要因素。