同步辐射软X射线引起小麦根尖细胞凋亡的研究

采用不同剂量的软X射线辐照小麦种子,利用DAPI荧光染色和TUNEL原位标记对种子萌发后的根尖细胞进行细胞凋亡的检测。结果表明,在剂量为0-288J／cm^2范围内的软X射线辐照能引起小麦根尖细胞的凋亡现象（如细胞形态学变化及细胞核内DNA的断裂等）发生,细胞凋亡率与同步辐射软X射线辐照剂量呈正相关性。     

同步辐射软X射线对单细胞的辐射损伤

应用国家同步辐射实验室软X射线显微术光束线的光学系统,搭建了适合软X射线单细胞辐照损伤效应研究的实验装置,选择氧元素K吸收边能量对Hela细胞进行单细胞辐照,运用单细胞凝胶电泳技术进行辐照损伤评价.实验结果表明,辐射损伤效应与辐射剂量有依赖性关系.     

单细胞凝胶电泳技术检测碳离子束和X射线照射对Lewis肺癌细胞的DNA损伤

比较研究了 89.63 MeV/u 的碳离子束和 6 MeV 的 X 射线照射 Lewis 肺癌细胞所致的细胞克隆存活和DNA 损伤效应,以探讨单细胞凝胶电泳检测细胞辐射敏感性及重离子束治疗肿瘤的优势.结果表明,在 10%细胞存活水平上碳离子束的相对生物学效应(Relative biological effectiveness,RBE)值达到1.77.单细胞凝胶电泳检测损伤 DNA 尾部百分含量(Tail DNA,TD)和Olive尾矩(Olive tail moment,OTM)的剂量效应曲线表明,X射线的剂量效应曲线为线性,而碳离子束诱导出-个包含线性和指数项的双阶段效应曲线.碳离子束辐照剂量大于8 Gy后TD和OTM都存在饱和效应.在2 Cy的剂量点,高传能线密度(LET)碳离子束比X射线产生更低的存活分数和更高的初始 OTM.本研究提示:在Lewis肺癌细胞中,碳离子束照射比x射线产生更为强烈的细胞致死和DNA损伤效应,可使肿瘤治疗具有更高效率.     

SOD对γ射线辐照枯草芽孢杆菌的保护效应研究

为了考查外源SOD对γ射线辐照微生物的保护效应,选用不同剂量γ射线辐照外源SOD处理过的枯草芽孢杆菌营养体,采用平板计数法考查辐照后的细胞存活率,黄嘌呤氧化法检测胞内SOD活性,脉冲场凝胶电泳分析DNA双链断裂水平的变化.结果表明,不同浓度外源SOD均可使γ射线辐照后的细胞存活率明显增加;营养体胞内残留SOD活性与外源SOD浓度以及辐照剂量之间的关系没有明显的变化规律;外加SOD使细胞DNA.双链断裂水平(PR)显著下降.并且细胞存活率和PR值随外源SOD浓度以及辐照剂量变化的趋势基本一致.研究结果显示外源SOD在γ射线辐照中对枯草芽孢杆菌有保护效应,且SOD的保护效应与其浓度呈一定相关.     

酵母β-葡聚糖对人脐静脉内皮细胞的辐射防护作用

研究酵母β-葡聚糖(BG)对X射线辐照致人脐静脉内皮细胞(Eahy926)损伤的防护作用。用四甲基偶氮唑盐(MTT)法评价BG的Eahy926细胞毒性,筛选出BG的最佳浓度和作用时间(10μg/mL,24 h)。用克隆存活法分析BG对Eahy926细胞辐射敏感性的影响。在X射线辐照至吸收剂量2Gy后0.5和24 h,用流式细胞仪分析细胞凋亡分布、DNA损伤和细胞内活性氧(ROS)水平,并用试剂盒检测超氧化物歧化酶(SOD)活性和过氧化氢酶(CAT)活性。结果显示:BG对Eahy926细胞无毒性作用;与单独辐照组相比,BG预处理能减轻X射线辐射损伤,显著提高X射线辐照后细胞的克隆存活率;辐照后同一时间点,BG预处理组细胞DNA损伤、细胞凋亡率和细胞内ROS水平都明显低于单独辐照组;而BG预处理组细胞SOD和CAT酶活性均明显高于单独辐照组;在辐照后0.5和24 h,BG预处理组DNA损伤修复率高于单独辐照组。结果表明,BG对X射线造成的Eahy926细胞损伤有一定防护作用,其机制可能与BG清除细胞内自由基、提高抗氧化酶活性、减轻DNA损伤和细胞凋亡、促进DNA损伤修复有关。     

Kovar封装CMOS器件X射线剂量增强效应研究

在器件的金属化层及封装等结构中，高原子序数材料在低能X射线的辐照下，会在相邻的低原子序数材料中产生剂量增强效应，从而使得器件性能严重退化。主要介绍了柯伐封装的CMOS器件，在X射线和γ射线辐照下，其辐照敏感参数阈值电压和漏电流随总剂量的变化关系。并对实验结果进行了比较，得出低能X射线辐照对器件损伤程度大于γ射线，对剂量增强效应进行了有益的探讨。     

~(60)Coγ射线与EMS复合处理小麦的诱变效应

采用多种处理组合、处理方法以及多种生物学指标,探讨了γ射线与EMS复合处理小麦的诱变效应。试验结果表明:γ射线与EMS复合处理的M_1代损伤随处理剂量的增加而增大,呈累加效应或协同效应。M_1代植株的生物学损伤与幼苗高度及幼苗根尖微核细胞密切相关。γ射线与EMS复合处理比单一处理提高了M_2代诱变效应。适宜的剂量组合可增加M_2代形态突变频率,扩大突变谱,并可增加某些数量性状的变异幅度。其中5.16C/kg的γ射线+0.31%EMS是比较理想的剂量。在复合处理中,可以M_1代幼苗根尖单微核细胞率估测M_2代的诱变效应。     

低剂量γ射线辐照对斑马鱼胚胎的发育和遗传毒性效应

为研究低剂量γ射线辐照对水生生物的发育和遗传毒性效应,以模式生物斑马鱼为研究对象,采用生物细胞辐照仪对5 hpf的斑马鱼胚胎进行不同累积剂量（0.01～1.00 Gy）的γ射线辐照处理,分析了胚胎的存活率、孵化率、畸形率和DNA损伤以及发育至150 dpf的F1代斑马鱼成鱼的繁殖能力及肝脏、肾脏和脾脏抗氧化酶的活性。结果表明：0.01 Gy低剂量γ射线辐照对斑马鱼胚胎存活率和孵化率无显著影响,但畸形率和DNA损伤显著提高;当辐照剂量超过0.10 Gy时,存活率和孵化率显著降低。5 hpf的斑马鱼胚胎接受0.01 Gy低剂量的γ射线辐照后,发育至150 dpf的F1代斑马鱼成鱼,产卵量显著降低,且具有剂量依赖性;肝脏的CAT酶的活性显著升高,表明它可能是评价低剂量γ射线辐照毒性效应潜在的生物标记物。     

单细胞凝胶电泳技术用于生物体系辐射损伤评价

采用单细胞凝胶电泳技术(single cell gel electrophoresis, SCGE),又称彗星电泳,表征不同剂量α, γ射线照射诱导健康人体外周血淋巴细胞DNA和小鼠活体与离体外周血淋巴细胞DNA瞬时损伤的剂量效应关系,建立了α, γ射线辐照剂量刻度曲线,并对活体小鼠的辐射损伤进行了吸收剂量估算,对辐射危害进行了评价.结果表明,单细胞凝胶电泳技术能够精确表征射线所致生物体损伤的生物学效应,而且能够对辐照后生物体的吸收剂量、尤其是辐射事故后的生物体进行剂量离线评测,建立生物体辐射损伤事后评测机制.     

米曲霉孢子对同步辐射C、N、O元素K吸收边附近软X射线的吸收剂量分布研究

以C、N、O元素的K吸收边附近能量的软X射线为辐射光源,通过模型分析,比较了米曲霉孢子不同部位对不同能量软X射线吸收剂量分布.同时利用合肥同步辐射软X射线显微术光束线准单色的软X射线对孢子进行辐照实验,对不同能量辐照存活率结果进行了比较.理论分析表明,由于C、N、O元素K吸收边效应以及孢子不同部位元素组成的不同,受照时孢子不同部位对软X射线的吸收剂量分布随能量变化存在差异.实验结果显示,3种元素K吸收边附近软X射线对米曲霉孢子均有很强的辐射失活效应,其中2.3nm波长的软X射线对孢子的辐射损伤效应要高于3.2nm和4.4nm波长的软X射线.     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.