人牙釉质中顺磁物质本底分布及其辐射敏感性差异

用电子自旋共振（ＥＳＲ）技术研究了健康成年人牙釉质中顺磁物质本底水平分布特性及其辐射敏感性。结果表明，在１８～４１岁年龄范围内，牙釉中顺磁物质本底水平在不同性别及不同年龄组间没有显著差别；不同个体样品辐照后信号强度的分散度并未增加，说明个体间对同种射线的辐射敏感性差异不大。提示在上述年龄范围内，用异体牙釉作辐射剂量估算是可行的。     

太阳光照射产生的牙釉质电子自旋共振信号的稳定性研究

对不同的牙釉质样品分别进行60Coγ射线和太阳光的照射,放置不同时间后,使用电子自旋共振(ESR)谱仪测量ESR信号的强度,研究不同种类辐射照射后牙釉质所产生的ESR信号强度随时间的变化。结果表明,60Coγ射线照射后产生的牙釉质ESR信号,其剂量学峰的信号很稳定。太阳光照射与γ射线照射具有相同的剂量学峰的信号,最后一次照射后2年半,其强度衰减约20%;紧邻本底和另一较弱信号衰减约30%;信号相对稳定,对剂量学信号和本底水平可能会有一定的影响。所以用牙釉质ESR信号的剂量学峰进行剂量重建时,尤其是在低剂量区域内,应该认真考虑并去除其他种类辐射引起的影响。     

影响窗玻璃γ辐射响应的电子自旋共振波谱研究

为更好应用于人员剂量估算和事故等级测定,探索了影响窗玻璃电子自旋共振波谱剂量学性质的因素。实验将窗玻璃处理成不同粒度大小,分别研究研磨处理对本底信号和辐射信号的影响。给予窗玻璃样本不同照射剂量,存储在不同条件下,观察温度、光线、时间等对电子自旋共振波谱(ESR)信号的影响。对比了来源不同的窗玻璃剂量响应曲线和最小检测剂量。结果表明,前期样本处理对窗玻璃辐射信号并无明显影响,但会产生机械信号;温度越高,窗玻璃辐射信号越不稳定。高温加热(≥200 ℃,≥5 min)可使照射后的ESR信号衰退至本底信号;透明袋-灯光和黑袋存储条件下的样本结果大致相同:11小时信号强度衰减9%左右,150小时衰减约18%。透明袋-阳光样品:11小时信号衰减了17%,150小时衰减38%。三种存储条件下的样本在150小时左右之后均达到稳定状态;窗玻璃样品在g=2.005 7处ESR信号与吸收剂量线性相关,线性相关性系数因来源于不同生产厂家而有差异。窗玻璃最小检测剂量是4~5 Gy。因此,在窗玻璃作为剂量计的实践中,注意以上问题,建立合理的剂量评估操作程序,可以估算出更为准确的结果。     

牛牙与人牙釉质电子自旋共振剂量学的比较研究

对牛和人类的牙釉质样品分别进行137Csγ射线照射,使用电子自旋共振(ESR)谱仪测量了所有样品照射前后的ESR信号强度,研究γ射线照射后不同种类的牙釉质所产生的ESR信号强度随剂量的变化。结果表明,137Csγ射线照射前,牛牙釉质的ESR本底信号明显低于人牙釉质的本底信号;与人牙釉质相同,牛牙釉质照射后产生的剂量学信号的强度与照射剂量线性相关,5组100mg牛牙釉质样品,其剂量学峰的辐射响应的平均值为(34.4±2.0)Gy-1,人牙釉质样品的辐射响应的平均值为(36.3±2.9)Gy-1,二者非常接近。所以当人类牙釉质样品缺乏时,可以用相同辐射环境中的牛牙釉质作为替代品,进行剂量重建。     

电子自旋共振波谱法检测含骨类食品的初步研究

电子自旋共振(Electron spin resonance,ESR)波谱测定是检测含骨类食品自由基的有效方法之一.本工作研究了辐照诱导的含骨类食品的ESR波谱特征、样品制备方法及辐射剂量-效应关系.结果表明,辐照前后ESR波谱图形、g因子和△H皆有明显差异,据此很容易区分辐照与未辐照含骨类食品样品;冷冻干燥和磨碎是样品制备过程中的关键步骤;吸收剂量(0.3-10.1kGy)与ESR信号强度有良好的线性关系;ESR信号的相对强度还与动物种类有关.这为制定我国含骨类辐照食品的ESR检测方法标准提供了依据.     

用牙珐琅电子自旅共振法测定早更新世古人类与石器地点年代的探索

研究了用牙珐琅电子自旅共振测年法测定早更新世古人类和石器地点年代中存在的若干基本问题：（1）指数拟合能否较准确地测定累积剂量;（2）牙珐琅ESR信号的热稳定性;（3）样品中铀加入模式;（4）珐琅中高铀含量对测年的影响。结果认为,对上述因素未完全了解和未做相应校正之前,早更新世牙珐琅的早期细加入ESR年龄很可能只是真实年龄的下限。     

微核测定法作为生物剂量计影响因素的研究

本文研究了应用双核淋巴细胞微核测定法作为生物剂量计时,培养液中细胞松弛素 B(Cyt-B)的有效浓度,培养的适宜时间;并对个体的自发微核率、辐射敏感性以及年龄的影响进行了探讨。结果表明,培养液中 Cyt-B 的浓度以6μg/mL 较为适宜,细胞培养72 h 比较合适;个体间自发微核率存在显著差异,且随年龄增加自发微核率呈增加趋势;个体间辐射敏感性也具显著差异,自发微核率与辐射敏感性间无相关性。     

ESR法测牙珐琅化石年龄中累积剂量测量的初步研究

研究了牙珐琅化石的ＥＳＲ信号对辐射剂量的响应关系，讨论了用指数函数拟合定牙珐琅累积剂量ＡＤ的适用范围和所产生的系统误差的大小，并以郧县古人类遗址牙珐琅样品为实例检验了上述研究结果。     

普通小麦品种辐射敏感性及其诱变效应的研究

利用~(60)COγ射线辐照含水量13%的小麦休眠种子,从形态学、细胞学和生理生化三方面综合研究了普通小麦品种辐射敏感性。结果表明,普通小麦品种间辐射敏感性存在显著差异,并呈正态分布。对供试的49个品种进行模糊聚类分析,普通小麦品种辐射敏感性分为极敏感 型、敏感型、中间型、迟钝型和极迟钝型五类。不同遗传背景品种的辐射敏感性强弱具有以下关系:重组品种>地方品种>辐射实变品种。植物品种辐射敏感性强弱取决于DNA损伤的自身修复能力。M_1辐射敏感性不同的品种,其M_2的诱变效果也不同。在7.74C/kg(30kR)以下的剂量范围内。对辐射敏感的品种实变频率高,数量性状的变异程度大。因此,在辐射育种上,选择敏感的品种作辐照材料可收到较好的效果。     

人成纤维细胞株辐射诱导凋亡与辐射敏感性相关性研究

为探讨不同放射敏感性人成纤维细胞株经辐射诱导后的凋亡情况,应用Ｔｕｎｅｌ法及流式细胞术（ＦＣＭ）检测细胞凋亡,以＾６０Ｃｏγ射线处理细胞。结果表明（１）＾６０Ｃｏγ射线照射后,集落形成实验表明,６号细胞株辐射敏感性高于８号细胞株。（２）Ｔｕｎｅｌ法和流式细胞术检测结果表明,凋亡率与辐射敏感性成正比,同样反映出６号细胞株辐射敏感性高于８号细胞株。（３）检测还发现,凋亡率与辐射剂量和辐射后时间成正比。     

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.     

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.     

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.