聚丙烯粉料固相光接枝丙烯酸的研究

为了提高聚丙烯(PP)的亲水性和染色性,以二苯甲酮(BP)为光引发剂、使用固相光接枝反应装置,采用固相紫外光接枝法在PP粒料表面接枝丙烯酸(AA)单体,并研究了单体含量、引发剂用量、辐照时间和溶胀时间对接枝率的影响规律,以及PP接枝前后力学性能的变化。结果表明,AA用量为1mL、引发剂用量为0.15g、辐照时间为30min、溶胀时间为12h时的接枝率最高。接枝率为5.2%左右,上染率为43.4%时,接枝PP的拉伸强度降了1.37MPa,但断裂伸长率从358.3%增加到396.3%,说明丙烯酸适度接枝对力学性能影响不大。     

辐射法制备聚丙烯酸-改性壳聚糖体系的两性凝胶

以O-马来酸酐化N-邻苯二甲酰化壳聚糖(MPCS)为中间产物,通过γ射线引发,在均相溶液体系制备含有改性壳聚糖.聚丙烯酸的两性凝胶.用红外光谱证实了接枝反应的发生.同时还系统地研究了接枝反应的影响因素,结果表明,接枝率依赖于单体浓度和所用的剂量.通过研究了接枝产物在不同pH值缓冲溶液中溶胀度的变化,结果发现,接枝产物在酸性条件(Ph<7)下溶胀较小,在碱性条件(pH>7)下溶胀度较大.而且还测试了接枝产物在DMF溶剂中的溶胀情况.     

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%。     

预辐射聚丙烯纤维接枝丙烯酸的研究

以电子束和＾６０Ｃｏγ射线为辐射源，对聚丙烯纤维分别在空气和氮氢气下进行预辐照，然后将样品置于丙烯酸水溶液体系中进行接枝反应。研究了吸收剂量、反应温度、反应时间、丙烯酸浓度等接枝率的影响，还研究了硫酸和硫酸亚铁等添加剂以及预辐照样品在室温下的存放时间等对接枝率的影响。比较了两种不同辐射源在预辐射接枝中的差别。     

微晶纤维素预辐照接枝丙烯酰胺

利用60Coγ辐射,以预辐照接枝技术制备出纤维素-丙烯酰胺接枝共聚物。研究了各种反应条件对丙烯酰胺接枝率和单体利用率的影响规律,利用傅里叶红外光谱对接枝产物进行了表征。结果表明,当反应时间3 h,辐照剂量35 kGy,反应温度40℃,微晶纤维素(Microcrystalline cellulose,MCC)与接枝丙烯酰胺(Acrylamide,AM)质量配比为0.5∶1,六水合硫酸亚铁铵(阻聚剂)添加量为AM质量的0.01%,AM单体浓度为5%时,可得到接枝率和单体利用率均达65%以上的接枝产物。     

不同分子量的丙烯酸酯对聚乙烯辐射接枝的研究

利用预辐射方法，在聚乙烯薄膜上接枝不同分子量的缩乙二醇丙烯酸酯单体。研究单体不同分子量的变化对接枝反应和接枝样品亲水性等的影响。结果表明：摩尔接枝率随单体分子量增加而非线性地降低；接枝基材的溶胀程度对分子量较大的单体的接枝反应影响较大；该片溶胀度越大，接枝率越高；单体分子量增加，接枝反应初速度下降。     

聚四氟乙烯微粉预辐照接枝丙烯酸的研究

采用预辐照法对聚四氟乙烯(PTFE)微粉进行接枝丙烯酸改性,以改善微粉在水溶液中的分散性.研究了丙烯酸体积分数、适量浓H2SO4的添加、阻聚剂质量浓度、反应时间等因素对接枝率的影响.结果表明,接枝率随着丙烯酸体积分数(在50%以内)增加而单调递增;适量浓H2SO4能增强阻聚剂的阻聚效果,提高接枝率;在本实验条件下,阻聚荆最佳质量浓度为0.8 g/L;反应在3 h后接枝率即可达饱和.当丙烯酸在PTFE微粉上的接枝率达到10%以上时,改性PTFE微粉在氢氧化钠溶液中可达到均匀分散.     

预辐射聚丙烯纤维接枝苯乙烯的研究

采用预辐射接枝法，对聚丙烯纤维分别采用电子束和＾６０Ｃｏγ射线在空气和氮气氛下进行辐照，然后将样品置于苯乙烯－甲醇溶液体系中进行接枝反应。研究了吸收剂量、反应温度、反应时间、苯乙烯浓度等对接枝率的影响以及预辐照样品的存放时间，存放条件等对接枝率的影响，并比较了两种不同辐射源在预辐射接枝中的差别。     

PVA膜共辐射接枝改性的初步研究

研究了温度敏感性聚合物聚Ｎ－异丙基丙烯酰胺在ＰＶＡ膜上的共辐射接枝反应，及吸收剂量，剂量率，单体浓度，无机酸及Ｃｕ＾２＋浓度妆枝率的影响，同时测定了接枝膜的溶胀性能。结果表明ＰＶＡ膜接枝后溶胀比增加且具有温度敏感性。     

辐射接枝制备聚丙烯纤维基海水提铀吸附剂

采用电子束预辐射接枝法将丙烯腈和丙烯酸接枝于聚丙烯(Polypropylene,PP)纤维上,并探讨了吸收剂量和反应温度对接枝率的影响。随后通过偕胺肟化反应制备出含偕胺肟基和羧基的PP纤维吸附剂。红外光谱数据表明,丙烯腈和丙烯酸成功接枝到PP纤维上,偕胺肟化反应将腈基转化为偕胺肟基,同时对改性前后PP纤维的表面形貌和热性能进行了表征。厦门海域真实海水吸附性能测试结果表明,所制备的PP纤维吸附剂铀吸附容量最高可达到0.81 mg·g~(-1)(吸附时间为68 d),PP纤维吸附剂的铀吸附容量与其接枝率和偕胺肟基密度不呈正相关。     

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.