低能电子辐照对环氧树脂性能的影响

为了研究低能电子辐照对环氧树脂的体积电阻率、邵氏硬度、拉伸强度和官能团结构的影响,本文在电子辐照能量为30 keV,注量率1×10~(11) cm~(-2)·s~(-1),总注量为1.6×10~(14) cm~(-2),真空度10~(-6) Pa条件下,结合国家标准对辐照前、后环氧树脂材料的机械性能和结构进行表征。结果表明,辐照后环氧树脂材料的体积电阻率、邵氏硬度、拉伸强度等宏观物理性能均有下降。傅里叶红外光谱图显示环氧树脂主要官能团强度降低,产生的·H、·OH等自由基与聚合物分子上的羟基与氢结合。研究结果对环氧树脂材料在辐射环境中的使用具有重要意义。     

喇曼光谱法研究辐照聚合物的气体产值

本文研究了两种典型交联型聚合物在~(60)Coγ射线辐照条件下放出的气体的激光喇曼光谱,通过波数2917cm~(-1),2954cm~(-1)和4157cm~(-1)三处特征谱峰高度与标准谱图的比较,测得辐照聚二甲基硅氧烷放出的各种气体产值:G_(CH_4)=1.05,G_(C_2H_6)=0.23,G_(H_2)=0.58,气体总产值:G_(CH_4-C_2H_6+H_2)=1.86,实验结果表明,在500Mrad剂量以下,辐照样品放出气体的总产值和各种气体的分产值不随剂量而变化,从而给予交联度与剂量成正比以直接证明。用同样方法测得辐照聚乙烯放出的气体产值(G_(CH_2)=2.7),也与辐照剂量无关。     

离子辐照GaAs的光致发光和拉曼散射研究

利用250 keV质子和4.5 MeV氪离子(Kr17+)辐照未掺杂GaAs,注量分别为1×10~(12)-3×10~(14) cm~(-2)和3×10~(11)-3×10~(14) cm~(-2),使用光致发光谱和拉曼散射谱分析表征。发光谱的结果表明,随着剂量增大,质子辐照后的CAs峰及其声子伴线逐渐减弱,913 nm处的复合缺陷峰则先增大后减小,此峰与材料制备时的Cu掺杂无关。Kr离子辐照后本征发光峰则完全消失。拉曼散射谱的结果表明,相比于质子辐照,Kr离子辐照后LO声子峰峰位向低频方向移动,出现非对称性展宽,晶体结构发生明显改变。质子和Kr离子辐照效应的差异是由于移位损伤相差至少三个量级造成的。最后采用多级损伤累积(Multi-step damage accumulation,MSDA)模型得到了材料内缺陷的演化过程,并很好地解释了随损伤剂量增大GaAs光学性能及晶体结构的变化趋势。     

环化聚苯乙炔耐γ辐照的研究

环化聚苯乙炔(简称CPBA)是一种高绝缘的特殊磁性的有机材料。它的分子构型特殊,故它既具有高浓度自由基又有高的稳定性。本文从下列三方面考察它耐γ辐照的情况。 (1)从红外光谱研究了三种不同剂量的γ射线辐照CPBA的样品,参比样品也在同样条件下进行辐照。红外光谱图表明:参比样品随着辐照剂量的增加,出现1700cm~(-1)谱带吸收强度的增加;但当γ辐照剂量从0到1.4×10~9rad时,CPBA红外光谱图形基本上未变化。因此,反映在化学结构上没有变化。故CPBA是耐γ辐照的。     

电子辐照对苎麻纤维结晶度的影响研究

为了降低苎麻纤维的结晶度,利用电子束对苎麻纤维进行了0–2000 kGy范围不同剂量的辐照,采用X射线衍射仪(XRD)和红外光谱(FT-IR)对辐照苎麻纤维进行了测试分析。X射线衍射图谱数字分峰分析得知苎麻纤维结晶度随辐照剂量增加而减小,红外光谱分析结晶度指数也随剂量增加而变小。且从红外光谱特征峰分析得知纤维中羰基组分随辐照剂量增加而升高。结果表明,利用电子束辐照可有效降低苎麻纤维的结晶度,而且可通过控制不同剂量的辐照得到苎麻纤维应用所需要的结晶度。     

同步辐射红外光谱研究结肠癌细胞的软X射线辐射效应

为探索红外光谱技术在辐射效应研究中的应用,以合肥同步辐射红外和远红外光谱实验站为平台开展软X射线低剂量辐射效应研究。用傅里叶变换红外显微镜光谱仪采集软X射线辐照前后的结肠癌细胞（HCT116）的单细胞光谱,分析光谱的位置和强度等变化。发现辐照后癌细胞吸收谱在峰的强度、位置都有明显变化,尤其位于1079 cm^-1、1236 cm^-1的核酸骨架磷脂对称和反对称振动吸收有明显的差异。研究表明:辐射诱导的癌细胞生物效应可以通过单细胞红外光谱灵敏表征;该方法有可能成为快速检测辐射效应的有效手段。     

固态羧甲基纤维素的电子束辐照降解

本文研究了电子束辐照降解固态羧甲基纤维素(CMC)效应。结果表明:辐照CMC固体样品配制2%水溶液粘度随着辐照剂量增大而减少;红外光谱分析表明,辐照导致CMC分子链上糖苷键C1-O-C4断裂。固态CMC辐照降解符合无规则降解动力学规律。     

氧化镁辐射接枝烯类单体的研究

本文研究了氧化镁辐射接枝苯乙烯及甲基丙烯酸甲酯。用红外光谱、X线衍射、裂解色谱等方法表征接技反应结果表明,MgO-g-MMA接技共聚物与MgO-PMMA共混物,在1380cm~(-1),1430～1480cm~(-1)处有不同的红外吸收峰,而且MgO-g-MMA接技共聚物在裂解色谱图上出现明显的4号峰,在X线衍射图上出现MgO的五个晶相峰外还出现另外五个晶相峰,它们的晶面间距分别为4.7702A、2.3618A、1.7926A、1.5703A、1.3084A,这说明由于MgO晶格影响MMA聚合生成某些规整的聚合物。证明辐射接枝聚合物是以化学键联结在无机物上的,而不是无机物和均聚物的混合物。接枝共聚物的分子量要比均聚物的分子量大,但分子量分布则较宽。辐射接枝后氧化镁和聚乙烯的亲和力有所增加。     

离子液体1-丁基-2,3-二甲基咪唑六氟磷酸盐对γ射线辐射稳定性研究

研究了憎水性离子液体1-丁基-2,3-二甲基咪唑六氟磷酸盐([BuMeMeIm]PF6),在氮气保护下,60Coγ射线照射,最大剂量为400 kGy的辐射稳定性。随着辐照剂量的增加,[BuMeMeIm]PF6的颜色逐渐加深,紫外-可见光谱(UV-Vis)中吸光度随辐照剂量的增加呈线性增长,但颜色及吸光度的变化均小于1-丁基-3-甲基咪唑六氟磷酸盐([BuMeIm]PF6)。辐照400 kGy后,[BuMeMeIm]PF6的傅利叶红外光谱(FTIR)和核磁共振氢谱(1H NMR)谱图均未出现变化。高效液相色谱法(HPLC)分析表明辐照400 kGy后,发生辐解的[BuMeMeIm]+的比例约为0.73%,小于同样条件下发生辐解的[BuMeIm]+。电喷雾质谱(ESIMS)结果显示[BuMeMeIm]+中N-butyl键的断裂可能是阳离子分解的重要原因之一。因此,咪唑环C(2)-H被甲基取代,将会增加咪唑阳离子的辐射稳定性,减小阳离子的辐射分解,使得[BuMeMeIm]PF6具有更高的辐射稳定性。     

SrSO4:Eu磷光体的热释光特性

研究了掺杂得到的SrSO4Eu(0.1mol%)的粉末样品的热释光(TL)发光曲线和三维光谱.用90Sr的β射线辐照0.116～1.16 kGy后.测到的热释光峰发光曲线,观察到只有一个主剂量峰,峰温位于(231.5±2.3)C.用热释光一般级动力学方程拟合发光曲线,得到了峰参数和陷阱参数值.主剂量峰基本上不随照射剂量发生变化,辐射剂量响应为线性-亚线性.用+0℃oγ辐照100Gy后.测量了热释光三维光谱,确定了发光波长主要位于375nm.与其他硫酸盐基质材料中掺Eu的CaSO4Eu.MgSO4Eu比较.波长有所不同.可以确定这是来自于Eu2+能级跃迁的发光.     

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.