人骨中232Th,230Th和228Th含量的测定

本文采用放化分离、电沉积制源、低温半导体α谱仪测量的方法测定了59例正常人(非钍尘作业人员)骨中~(232)Th、~(230)Th 和~(228)Th 的含量。测定结果表明,骨中~(232)Th 和~(228)Th 含量的均值分别为31、23和62 Bq/kg(鲜重),标准差分别为19、18和39 Bq/kg(鲜重),骨中钍所致的平均剂量分别为:~(232)Th,0.031 mrad/a;~(230)Th,0.027 mrad/a ~(228)Th,0.085 mrad/a。骨中~(230)Th 含量与年龄呈相关,吸烟与非吸烟者之间骨中三种钍核素含量差异均不显著。     

人骨骼中~(228)Th、~(230)Th和~(232)Th含量的同时测定

本文介绍了用α谱仪同时测定人骨骼中~(228)Th、~(230)Th和~(232)Th含量的方法。样品用浓 HNO_3和 H_2O_3湿灰化,草酸钙共沉淀载带、CL-5208萃淋树脂和743阳离子交换树脂联合分离后,电沉积制源,在低温半导体α谱仪上测量。该方法对~(234)Th的全程回收率为95.0±1.7%,对铀和镭的去污系数分别为6.3×10~4和1.5×10~3,对~(228)Th、~(230)Th、~(232)Th 的探测下限分别为0.432、0.135和0.108Bq/kg(鲜重)。     

北京建筑材料中天然放射性核素含量及其所致居民剂量

用φ75×75mmNaI(Tl)-塑料反符合γ谱仪分析了北京34种建材中的~(232)Th,~(226)Ra 和~(40)K 含量,平均值±标准差分别为(24±19)、(40±83)和(5.5±3.6)×10~2Bq/kg;由建材中~(226)Ra 含量算的北京室内~(222)Rn 浓度为29Bq/m~3;估算北京居民受天然辐射的年有效剂最当量为1.8mSv,其推中室内照射为1.5mSv。     

广西壮族自治区土壤中天然放射性核素含量调查研究

本文报道广西壮族自治区土壤中天然放射性核素含量调查的主要结果。基本与环境陆地γ辐射剂量率调查同位布点,全自治区共采集土壤样品383个,其中包括25 km×25 km 网格点样品360个,土壤类型加密点21个,特殊点2个。测量采用γ能谱法。调查结果表明,广西壮族自治区土壤(干样)中天然放射性核素~(238)U、~(226)Ra、~(232)Th、~(40)K 含量按面积加权平均值(±单次测量标准差)分别为:53.0(±32.7)、53.1(±35.2)、69.1(±34.6)和332.2(±234.4)Bq/kg。调查中发现“花山-姑婆山”一带土壤中天然放射性核素含量显著偏高,其土壤中~(238)U、~(226)Ra、~(232)Th、~(40)K 含量分别为170、184、211、766Bq/kg。     

北京地区人骨中^232Th活度及所致内照射剂量

本文报道了北京地区57例居民骨灰样品中~(232)Th 活度的中子活化分析结果。结果表明。人骨灰中~(232)Th 比活度的算术均值和中位数分别为7.6×10~(-4)和5.6×10~(-4)Bq/g,骨中~(232)Th 活度的算术均值和中位数分别为1.2和0.90Bq;所致骨表面细胞和红骨髓器官年吸收剂量分别为52μGy/a和4.0μGy/a;所致内照射的年有效剂量当量为41μSv/a,居民的膳食组成对这一结果可能有明显的影响。     

人体尸解组织中钍和钚的含量及其分布的比较

本文分析测定了日本北部新■县1986和1988年死亡的33例病人的部分尸解组织(包括骨、肺、肝、脾、肾和肌肉)中~(232)Th、~(230)Th、~(228)Th 和~(239+240)Pu 的含量,并估算了组织负荷量,对钍和钚在人体内的分布进行了比较     

巴西北里奥格朗德土壤中~(226)Ra、~(232)Th、~(40)K的分布

一项旨在调查巴西北里奥格朗德环境中放射性的计划已开始实施,在该区的东部和中部共采集52个土壤样品、2个岩石样品和2个含铀矿石样品。样品中的放射性元素含量采用γ射线能谱法确定。土壤中~(226)Ra,~(232)h和~(40)K的平均含量分别为29.2±19.5、47.8±37.3、704±437Bq·kg~(-1),所有放射性元素含量高的样品主要是岩石样,~(226)Ra和~(232)Th的分布呈对数正态。采用一台闪烁测量仪在所有取样位置上进行的放射性生     

丹东地区土壤天然放射性核素本底值调查研究北大核心CSCD

为明确丹东地区土壤天然放射性核素226 Ra、232 Th、40 K的本底值,以丹东地区代表性土壤为研究对象,使用RMS 4096-USB数字化低本底多道r能谱仪测定其0~10 cm土层226 Ra、232 Th、40 K放射性活度浓度,并用内梅罗综合评价法对其结果进行评价。结果表明:丹东地区0~10 cm土层土壤226 Ra、232 Th、40 K的平均放射性活度浓度分别为100.12 Bq·kg^(-1)、11.84 Bq·kg^(-1)、688.65 Bq·kg^(-1),内梅罗综合指数分别为3.17、0.35、1.07,与辽宁省均值比较,丹东226 Ra含量特高,232 Th微量,40 K偏高,处于全国测定结果范围内。     

铀钍矿石、土壤中,天然钍同位素的分光光度法-α计数(内闪)法联合测定

样品用过氧化钠熔融分解,草酸钙预沉淀分离杂质浓集后,溶于3mol/L HNO_3中,以4％P204-甲苯萃取,5％草酸反萃取,再次沉淀为草酸钙并溶于4mol/L HCl中,用偶氮胂Ⅲ分光光度法测淀钍(≈~(232)Th)含量。测量完毕,收集全部显色液重新沉淀出草酸钙,加入ZnS(Ag)混合均匀,用α计数(内闪)法测量总钍α计数(Th(α)_1),放置5天以上再测一次总钍α计数(Th(α)_2),根据两次α计数率的变化,计算得到样品中~(228)Th的含量。假定~(227)Th与~(230)Th在样品中近似保持放射系平衡的比例关系,则样品中~(230)Th含量等于总钍(Th(α)_1)减去~(232)Th(换算为活度)、~(227)Th(按与~(230)Th的比例关系)、~(228)Th及其子体总α活度之和。此法利用一般仪器设备,能较快得到总钍α-比活度、~(232)Th、~(230)Th和~(228)Th等四个天然钍同位素的重要数据,精密度、准确度满足常规分析要求,分光光度法对钍的测定限为0.06μg,α计数(内闪)法的4π探测效率为(95±1)％,本底计数率为(1.5±0.3)×10~(-3)Bq。     

铀钍矿石、土壤中,天然钍同位素的分光光度法-α计数(内闪)法联合测定

样品用过氧化钠熔融分解,草酸钙预沉淀分离杂质浓集后,溶于3mol/LHNO_3中,以4％P204-甲苯萃取,5％草酸反萃取,再次沉淀为草酸钙并溶于4mol/LHCl中,用偶氮胂Ⅲ分光光度法测定钍(≈~(232)Th)含量。测量完毕,收集全部显色液重新沉淀出草酸钙,加入ZnS(Ag)混合均匀,用α计数(内闪)法测量总钍α计数(Th(α)_1),放置5天以上再测一次总钍α计数(Th(α)_2),根据两次α计数率的变化,计算得到样品中~(228)Th的含量。假定~(227)Th与~(230)Th在样品中近似保持放射系平衡的比例关系,则样品中~(230)Th含量等于总钍(Th(α)_1)减去~(232)Th(换算为活度)、~(227)Th(按与~(230)Th的比例关系)、~(228)Th及其子体总α活度之和。此法利用一般仪器设备,能较快得到总钍α-比活度、~(232)Th、~(230)Th和~(228)Th等四个天然钍同位素的重要数据,精密度、准确度满足常规分析要求,分光光度法对钍的测定限为0.06μg,α计数(内闪)法的4π探测效率为(95±1)％,本底计数率为(1.5±0.3)×10~(-3)Bq。     

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.