阴离子交换预浓集-中子活化法测定近岸海水样品中的超痕量铱

利用放射性192 Ir示踪技术及近紫外 -可见吸收光谱分析 ,研究了阴离子交换树脂对海水中铱的吸附行为 ,建立了天然海水样品中铱的阴离子交换预浓集流程 ,回收率达 90 %。在超净条件下 ,采用此流程结合中子活化分析测得黄海近岸海水样品中的铱浓度为 2 .6× 10 - 14 g/mL。     

无锡坠冰水的中子活化研究

本文用中子活化法研究了无锡坠冰水中的痕量元素丰度,发现坠冰水中的铱浓度为正异常,达3.16×10~(-12)g/g。利用实验结果,计算了一系列元素之间的相互比值,坠冰水中的Ir/Co、Ir/Cr、Ir/Sc、Ir/Sr、Sc/Cr和Sr/Cr比值分别为6.88×10~(-3)、2.40×10~(-4)、1.09×10~(-1)、6.28×10~(-3)、2.21×10~(-3)和3.8×10~(-2),与Cl型陨石的10.2×10~(-3)、2.08×10~(-4)、0.92     

放射性核素在页岩和黄土中的迁移研究

介绍了 8 5Sr和 1 34 Cs在页岩 ,85Sr、1 34 Cs和 6 0 Co在黄土中的迁移研究结果。在页岩中 85Sr、1 34 Cs的滞留因子分别为 80～ 1 0 2和 1 60 0 0 ,分配系数分别为 1 5～ 2 5 m L/ g和 41 85 m L/ g;85Sr、1 34 Cs和 6 0 Co在黄土中的滞留因子分别为 45 0～ 5 3 0、4.1× 1 0 4 ～ 4.6× 1 0 4 和 3 .2× 1 0 4 ～ 3 .6× 1 0 4 ,分配系数分别为 80～ 86m L/ g、7.3× 1 0 3～ 7.5× 1 0 3m L/ g和 5 .7× 1 0 3～ 5 .8× 1 0 3m L/ g。结果表明 ,页岩对 85Sr和 1 34 Cs有较强的吸附性 ,黄土对 85Sr、1 34 Cs和 6 0 Co的吸附性极强。     

矿样和高纯铜中贵金属元素的中子活化分析

本文提出用二硫代氨基甲酸类苯乙烯二乙烯苯螯合树脂作辐照前预浓集预分离的中子活化分析法测定低品位矿样和高纯铜中微量贵金属元素,在盐酸体系中树脂对Au、Pt、Ir和Ru的化学回收率分别为99.7、99.5、95.6和84.3％,样品液经螯合树脂一步分组分离后,树脂干燥、灰化,和标准一起进堆辐照。中子通量3×10~(13)n/cm~2·s、照射50小时、冷却七至十天,用高分辨率同轴型130     

DPF中子参数实时测量技术研究

简要叙述了利用银活化中子计数器作为参考标定源 ,研制出一个闪烁体 +光电倍增管中子探测系统 ,实时测量 DPF中子参数 ,其中子产额为 8× 10 8～ 2× 10 9n/pulse之间 ,其半高宽 ( FWHM)值大为 30～ 60 ns之间     

高压倍加器辐射防护初步评价

本工作主要是对一台高压倍加器的辐射场进行了测量。结果表明,目前该高压倍加器的运行是安全的。实验厅内中子剂量主要来自电缆沟和迷宫的散射。在中子产额为2×10~9中子/秒条件下运行30分钟,距靶20厘米处由于中子活化引起的γ辐照率约20微伦/秒。机械泵油中氚的浓度为3×10~(-5)居里/升,机械泵排出口氚的浓度在(4×10~(-8)～3×10~(-6))范围内。     

三辛基氧膦涂层玻璃碳电极伏安法及其在海水中预富集后微量铀酰离子的测定

本文叙述了三辛基氧膦(TOPO)涂层玻璃碳电极(GC)的伏安特性和它在测定微量铀酰离子的应用。在已试验的各种物质中,对Ag/AgCl电极为0V时只有铀酰离子有效地被富集到GC电极上的TOPO层中,并且在电极电位负向扫描时给出还原波。有些物质可通过TOPO层的GC面,并且起电化学反应,而其他某些物质不通过TOPO层。用本法在0.5 M NaCl测定铀酰离子,预富集后用醋酸盐缓冲溶液调节pH到4;探测极限是2×10~(-9)M,可以测定的铀酰离子浓度在2×10~(-9)M和2×10~(-7)M之间。这种方法对铀酰离子是非常有选择性的,可用于分析海水中的铀。对人工的海水初步研究表明,简单的顶处理,包括在pH2.5时煮沸(除去溶解的二氧化碳)后即可测定。     

示踪技术在照前预浓集中子活化分析中的应用

采用高比活度放射性示踪剂测定了照前预浓集中子活化分析中的化学产额，该技术已应用于钢和岩石试样中微量Au,Ir和Re(含量约1－20ng/g(试样））的分析测定，还对放射化学中子活化分析和照前预浓集中子活化分析中化学产额测定的准确度差异作了探讨。     

用离子对液相色谱法测定工业水体中的铀

在吸附十二烷基硫酸铵改进的Separon SGXC18填充玻璃柱(3mm×150mm)上,用离子对液相色谱法使U(Ⅵ)与Th(Ⅳ)、Zr(Ⅳ)、Al(Ⅲ)、Fe(Ⅲ)、镧系元素和其他离子分离后,可以有效地测定0.3—1.0mol/L范围的U(Ⅵ)。用异箱洗脱法或pH或浓度梯度洗脱法,采用2-羟基-2-甲基丙酸铵或柠檬酸铵溶液,可以在分析交换柱上直接从酸性水溶液预富集微量铀并与Th、Zr、Al,Fe、镧系元素和其他元素分离,富集因子约为100,回收率为98±8％。利用pH2.7的0.1mol/L甲酸盐缓冲液中后柱与25μmol/L偶氮砷Ⅲ的衍生作用来检测和定量。     

多种锕系元素共存体系中微量~(235)Np的测定

本文为从复杂的多种锕系元素共存体系中准确测定超微量~(235)Np(10~(-15)-10~(-14)g/g)的含量,建立了一个特殊的中子活化分析流程。样品经阴离子交换柱浓集和PMBP萃淋树脂柱分离纯化,共存的~(237)Np作内标,高注量堆中子活化后,测定~(235)Np活化产物子体~(236)Pu而获得~(235)Np的含量。     

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.