γ射线共辐照接枝聚偏氟乙烯超滤膜表面亲水性研究

采用γ射线液相共辐照法对聚偏氟乙烯(Poly(vinylidene fluoride),PVDF)超滤膜进行接枝改性,研究了单体浓度、辐照剂量、链转移剂异丙醇(Isopropanol,IPA)、盐酸(Hydrochloric acid,HCl)、阻聚剂CuSO4浓度对接枝率及膜表面亲水性的影响.结果表明,在所涉实验条件下,接枝率随辐照剂量和接枝体系中单体浓度的增大,随CuSO4及IPA含量的增大而减小,改性膜表面接触角表现出相反的趋势;接枝体系中HCl的添加可以显著提高接枝率,有效降低改性膜表面接触角;改性后PVDF超滤膜表面亲水性显著提高,表面接触角由改性前的83.3°可降低至改性后的39.2°.     

预辐射接枝丙烯酰胺改性PVDF粉体及其亲水性滤膜的制备

通过γ射线预辐射接枝方法将丙烯酰胺(Acryl amide,AAm)单体接枝到聚偏氟乙烯Poly(vinylidene fluoride),PVDF]粉体上,通过测定粉体接枝前后氟元素含量的变化来计算接枝率.研究了同一单体浓度下,接枝率随反应时间的变化规律,并将具有不同接枝率的改性粉体溶解在N-甲基吡咯烷酮(N-met...     

聚醚砜微孔膜电子辐照接枝改性及过滤性能研究

利用电子束辐照技术对聚醚砜（PES）微孔膜进行接枝丙烯酸（AA）改性。用称重法测量接枝率,分析辐照剂量及气氛对膜接枝率的影响规律,用红外光谱分析膜接枝后官能团的变化,用扫描电镜观察样品的表面形貌;并分析了接枝率对水通量及牛血清白蛋白（BSA）溶液通量的影响。研究结果表明,对浓度为1mol/L的单体丙烯酸,在氮气或空气的氛围下辐照,接枝率随辐照剂量的增加先增大而后降低,并在整个辐照剂量范围内,氮气氛围下辐照的接枝率均高于空气氛围的接枝率。当接枝率较小时,水通量及BSA溶液通量均随接枝率的增大而增大,并当接枝率为11%时,二者同时达到最大值,随着接枝率的进一步增大,其值反而降低。     

苎麻纤维预辐照二步接枝胺化提高染色性研究

通过电子束预辐照将丙烯酸（AA）接枝到苎麻纤维上形成苎麻-g（接枝）-AA,再用乙二胺（EDA）对苎麻-g-AA进行预辐照接枝胺化形成苎麻-g-AA-EDA,讨论了预辐照接枝率和胺化率与单体浓度的关系。在此基础上对改性苎麻纤维进行无盐染色实验,分析了AA接枝率和EDA胺化率对其上染率的影响。结果表明：苎麻纤维通过预辐照成功接上AA,并进一步接枝EDA实现了胺化,且AA的接枝率和EDA的胺化率随单体浓度的增加而增大,当吸收剂量为40 kGy、EDA浓度为35%时,AA接枝率为25%的苎麻-g-AA样品的EDA胺化率可达20.1%;接枝AA后的苎麻纤维上染率降低,且随AA接枝率的增大而减小,当AA接枝率为25.1%时,上染率低至4.2%;胺化后的苎麻-g-AA-EDA纤维上染率较未胺化的苎麻-g-AA纤维的上染率明显提高,上染率随胺化率的增加而增大,AA接枝率约为25%、胺化率为25%的改性苎麻纤维的上染率达49%。     

紫外辐射引发聚丙烯接枝马来酸酐-苯乙烯的研究

将紫外辐射技术应用到本体接枝改性,成功制备了聚丙烯的马来酸酐-苯乙烯接枝物(PP-g-(MAH-co-St)),并用红外光谱对接枝物进行了表征.研究了紫外光辐照时间、单体及引发剂(BP)浓度等因素对接枝率及熔体流动速率的影响.结果显示,辐照时间为30 s时,接枝效果最佳.接枝率及熔体流动速率随BP含量的增加呈现先增加后降低的趋势,分别在BP用量为0.6g/100g PP及0.4g/100g PP时达到最佳值.MAH及St浓度对接枝率及熔体流动速率的影响与BP浓度的影响相似,其最佳用量为4 g/100 g PP.St的存在对接枝反应有明显的改善作用.接枝物的热性能分析显示,接枝PP的结晶及熔融温度都有所变化,说明接枝反应对PP的晶体形貌及尺寸有显著影响.     

辐照接枝改性涤纶织物的亲水性能

利用电子束辐照接枝的方法将丙烯酸(Acrylic acid,AA)单体接枝到涤纶织物上来改善其亲水性。通过改变吸收剂量、接枝单体浓度、阻聚剂浓度、预辐照的吸收剂量以及前处理氢氧化钠浓度等影响因素来获得具有不同接枝率的改性涤纶织物。优化的反应条件:吸收剂量为195 k Gy、AA浓度为50%、阻聚剂(Fe SO4?7H2O)浓度为0.8%、预辐照的吸收剂量为43 k Gy、前处理Na OH浓度为15 g/L。傅里叶红外光谱证明AA已接枝成功;扫描电子显微镜分析表明改性涤纶织物的表面具有覆盖物,且随着接枝率的增大,其覆盖物明显增多;回潮率测试结果表明,改性涤纶的回潮率随接枝率的增加而逐渐增大,当接枝率达到最大值27.84%时,改性涤纶的回潮率可达3.51%。涤纶织物经30次洗涤后减重率仅1%左右,说明接枝牢度优异。     

聚苯乙烯球珠辐射接枝丙烯酰胺

本工作研究放射免疫检测用的聚苯乙烯球珠辐射接枝丙烯酰胺的情况,並观察经化学处理的球珠(改性球珠)结合免疫球蛋白的能力。实验结果表明,接枝反应在3h内基本完成,接枝温度60℃左右接枝率最大,高剂量率辐照接枝率较低,吸收剂量和单位浓度增加,接枝率也增加,辐照时生成的过氧化物在室温下的分解半衰期约50h。改性球珠结合免疫球蛋白的能力大于原球珠,並随接校率的增加呈现有规律的变化。     

电子束预辐照聚丙烯接枝丙烯酸和丙烯腈的研究

研究了以电子束辐照预处理聚丙烯(PP)无纺布接枝丙烯酸(AA)和丙烯腈(AN)，AA与AN的共接枝的最佳反应条件是：辐照剂量为200kGy，反应温度为75℃，反应4h，添加剂用硫酸约0．05moL／L，摩尔盐为0．08％，且单体比例为40／60、浓度为50％，同时也探讨了阻聚剂[（NI-h)2Fe(SO4)2]对反应接枝率的影响。FT-IR结果反映了单体浓度变化时总接枝率的变化情况，单体比例对总接枝率的影响与其单体自身的稳定性有关，但总接枝率在所给定的单体浓度范围内一直增大。     

羊毛辐射接枝甲基丙烯酸缩水甘油脂研究

对甲醇溶液中甲基丙烯酸缩水甘油脂在羊毛纤维上的γ射线辐射接枝反应作了系统研究。考察了气氛、剂量、剂量率、单体浓度等实验条件对接枝反应的影响，发现气氛对接枝反应的影响很小，而接枝率随辐照剂量和单体浓度的增大而提高，接枝效率则随单体浓度的增大而减小。在剂量大于11kGy后接枝率达到平稳状态。用红外吸收谱仪(IR)和扫描电镜(SEM)分析发现单体均匀地接枝在羊毛上。     

SBS辐射接枝共聚研究(II):线型SBS液固相辐射接枝MAA

利用γ射线辐射接枝法制备苯乙烯-丁二烯-苯乙烯(Styrene-Butadiene-Styrene,SBS)粉体接枝甲基丙烯酸(MAA)聚合物,讨论了单体浓度、辐照剂量、气氛及辐照状态等因素对接枝率的影响,并采用傅立叶红外光谱(FT-IR)、差示扫描量热分析(DSC)、凝胶渗透色谱(GPC)、扫描电镜(SEM)、动态剪切流变(DSR)等分析手段对接枝聚合物进行了表征。研究结果表明,平均粒径为0.2mm的线型SBS粉体在辐照剂量为12kGy、剂量率为0.75kGy/h、MAA/SBS的质量比为0.6时,可获得最大接枝率。FTIR谱出现1705cm-1处羰基的吸收峰证实了接枝聚合物的存在,分子量分布测定表明SBS?g?MAA聚合物的分子量分布变宽,动态剪切流变中接枝聚合物的粘度增大,表明单体在SBS链上有接枝链的增长;热分析曲线中聚苯乙烯嵌段的玻璃化转变温度升高,损耗因子转折温度升高,都说明单体MAA对PS嵌段的影响较大。     

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.