国产改进型316L不锈钢的微结构研究

采用正电子湮没寿命方法研究了国产改进型316L不锈钢的微结构及其温度变化。该不锈钢含有单空位、双空位、位错和小空位团等缺陷。经400℃,600℃,800℃退火后,单空位、双空位和位错缺陷分别消失。小空位团是四空位和五空位构成的空位团,低于200℃退火,缺陷复合五空位团成分随退火温度升高而增大,高于400℃时空位团分裂,五空位团成分减少,800℃退火还存在较低浓度的四空位团。     

1.55 MeV 3He离子辐照单晶Si引起的损伤效应研究

室温下使用1.55 MeV、5×1013-5×1016/cm2注量的3He离子注入单晶Si,采用透射电子显微镜(TEM)观测分析了高温退火后单晶Si中由注入引起的损伤形貌,同时使用核反应分析(NRA)技术研究了3He气体原子的热解吸.结果显示,低注量3He离子注入在Si中产生的缺陷主要为一些小尺寸的位错或位错环;在中等照射剂量,退火导致了气泡和气泡团簇的形成并伴随着高密度的位错环从这些气泡团簇中发射出来;而对于较高的照射剂量,3He离子注入加上随后的高温退火则在离子射程附近产生了一个具有确定边界的空腔带.结合NRA结果对实验现象进行了分析.     

质子辐照钼退火行为的正电子寿命谱学研究

室温下用3.2MeV质子对多晶纯钼样品进行了辐照,用正电子寿命测量技术研究了辐照损伤及晶格缺陷在293～1138K温区内的退火行为,得出了许多有关空位团生长以及氢-缺陷相互作用的信息。辐照后在Mo中产生2～3个空位的聚集体,其浓度随辐照剂量增加而增加。从所测得正电子寿命、强度参数的变化获知高温退火后空位团的增长行为以及氢原对空位团长大的影响。     

质子辐照钼退火行为的正电子寿命谱学研究

室温下用3.2MeV质子对多晶纯钼样品进行了辐照,用正电子寿命测量技术研究了辐照损伤及晶格缺陷在293～1138K温区内的退火行为,得出了许多有关空位团生长以及氢-缺陷相互作用的信息。辐照后在Mo中产生2～3个空位的聚集体,其浓度随辐照剂量增加而增加。从所测得正电子寿命、强度参数的变化获知高温退火后空位团的增长行为以及氢原对空位团长大的影响。     

国产改进型316L不锈钢的微结构研究

采用正电子湮没寿命方法研究了国产改进型316L不锈钢的微结构及其温度变化，该不锈钢含有单空位，双空位，位错和小空位团等缺陷，经400、600、800℃退火后，单空位，双空位和位错缺陷分别消失，小空位团是由四空位和五空位构成的空位团。低于200℃退火时，缺陷复合五空位团成分随退火温度升高而增大；高于400℃时，空位团分裂，五空位团成分减少；800℃退火仍存在较低浓度的四空位团。     

慢正电子束研究质子辐照CLAM钢产生的缺陷及其退火行为

为了研究中国低活化马氏体CLAM钢的辐照损伤机理,本文利用慢正电子技术研究了质子辐照CLAM钢时所产生的缺陷及其退火回复行为,发现辐照在材料中产生空位团数密度随质子注量增加而增多,而其尺度增大并不明显.辐照仅产生原子尺度的空位和空位团,400℃退火可以使缺陷很好地消除.此外分析了硅对CLAM钢辐照性能的影响,实验上没有观察到硅的添加抑制了质子辐照缺陷的产生.     

注入Nb+的蓝宝石晶体退火前后的光学分析

将Nb⁺ 在不同条件下注入不同晶向的蓝宝石晶体，然后，在还原性气氛下退火，并对退火前后的蓝宝石晶体进行光学分析。分析结果表明，Nb⁺ 注入蓝宝石晶体产生的色心缺陷主要集中在紫外和可见光的高能区。通过对光吸收谱进行高斯拟合及荧光谱分析确认，引起吸收的点缺陷主要是F、F⁺、F₂、F⁺₂、F²⁺₂心等阴离子空位。退火可使这些色心点缺陷减少。退火温度越高，色心点缺陷减少越多，且减少的程度与注入温度有关。此外，700nm处的荧光峰随激发光波长变化而呈现出不同的变化趋势。     

BCC金属Nb的重离子辐射损伤研究

采用81 MeV碳离子辐照,模拟中子注量为10~(23)/cm~2的堆中子在Nb中产生的辐射损伤,用时间微分扰动角关联和正电子湮没二种方法研究辐射损伤及其高温退火效应。实验发现经注量2.5×10~(16)/cm~2的碳离子辐照后,在BCC金属Nb中产生单空位和双空位二种缺陷。随退火温度升高,双空位分解,单空位的总浓度逐步减小,经过1058K退火后,在Nb中由辐射损伤造成的缺陷消失。     

Al2O3/ZrO2纳米复合陶瓷的微结构及缺陷的正电子寿命研究

纳米Al_2O_3/ZrO_2复合陶瓷具有优良的力学性能,良好的高温稳定性和化学稳定性,并具有良好的抗辐照效应,是目前极具潜力的一种纳米陶瓷材料。采用正电子寿命谱分析同时配合着X射线衍射(X-ray Diffraction,XRD)和透射电子显微镜(Transmission Electron Microscope,TEM)对纳米Al_2O_3、ZrO_2和Al_2O_3/ZrO_2复合陶瓷在不同退火温度下(室温-1 000℃)的微结构及缺陷进行了研究。XRD研究表明:Al_2O_3、ZrO_2和Al_2O_3/ZrO_2纳米复合陶瓷三种样品退火温度低于500℃时,晶粒尺寸保持不变;随着退火温度的增加,Al_2O_3晶粒尺寸变化不大,ZrO_2和Al_2O_3/ZrO_2有所增加,但由于Al_2O_3的抑制,Al_2O_3/ZrO_2的晶粒生长更缓慢。正电子寿命分析表明:样品内主要缺陷是空位、空位团和微孔洞,缺陷主要集中在晶界处。对比ZrO_2纳米陶瓷内缺陷,Al_2O_3和Al_2O_3/ZrO_2纳米复合陶瓷内空位团或微孔洞缺陷尺寸更大,而相对数量更少。退火温度低于500℃时,三种样品内平均缺陷密度基本不变,高于500℃时由于晶粒生长,缺陷开始恢复,ZrO_2变化更明显,而Al_2O_3/ZrO_2由于相互抑制对方的晶粒生长,稳定性更高,这与XRD结果一致。纳米Al_2O_3的TEM图显示出晶粒大小基本不随退火温度变化发生改变,而纳米Al_2O_3/ZrO_2只有在退火温度高于500℃时,晶粒开始慢慢长大,并且发生了团聚,非常直观地证实了XRD和正电子的实验结果。     

电镀纳米镍缺陷的正电子研究

用正电子寿命谱研究了电镀纳米镍（～２０ｎｍ）中的微观缺陷，分析了缺陷中氢对正电子寿命的影响，实验结果表明，界面存在单空位大小的自由体积，６－１０个空位大小的自由体积和微孔洞三类缺陷，纳米镍在５００℃真空退火２ｈ后，中间寿命和最长寿命的强度不受影响，表明中间寿命和最长寿命所对应的缺陷具有很好的热稳定性。     

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.     

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。     

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.     

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.     

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.     

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.     

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.