聚丙烯与丙烯酸的辐射接枝反应的研究Ⅱ——预辐照聚丙烯的接枝共聚反应

本工作采用~(60)Coγ射线预辐照方法,研究聚丙烯毡在丙烯酸水溶液中的接枝共聚反应动力学。探讨了预辐照剂量,辐照气氛,接枝反应温度以及单体浓度对接枝共聚反应的影响。实验结果表明接枝反应速率与预辐照剂量的关系为0.445次方。由此得知反应是按自由基机理进行的。此外,计算了本体系的表观活化能为25.52kcal/mol。由本试验获得的接枝共聚物,其亲水性、透气性、及染色性均有明显地改善。但预辐照剂量超过1×10~6rad机械强度有所下降。     

聚氟乙烯-苯乙烯共辐照接枝反应的研究

用~(60)Co-γ射线共辐照法作了聚氟乙烯薄膜-苯乙烯的辐射接枝共聚合反应,研究了单体浓度、辐照剂量率、温度及薄膜厚度与接枝共聚反应速度的关系。在实验条件下,接枝共聚反应速度分别与单体浓度、辐照剂量率及薄膜厚度的2.5、0和-1次方相关联。接枝共聚反应的总活化能为141 8kJ/mol。     

取向聚四氟乙烯接技丙烯酸共聚物的形态结构和性能研究

用光学显微镜、电子显微镜、Ｘ射线衍射等方法对不同拉伸度聚四氟乙烯（ＰＴＦＥ），和对其γ辐射接技丙烯酸（ＡＡ）接枝共聚物的结构进行了研究。．结果表明，未接枝取向的ＰＴＦＥ，在γ射线辐照下产生大小不等的空穴，接枝丙烯酸填充在这些空穴中，形成粒状分散相微区结构，接枝量增大形成接枝链束，而使双折射增加。并对接枝共聚物结构和性能关系进行了讨论。     

明胶与甲基丙烯酸甲酯辐射接技共聚反应的研究

本工作采用~(60)Coγ射线辐照法,研究了明胶与甲基丙烯酸甲酯在水溶液中接枝共聚反应。实验结果表明:接枝率和接枝效率起先随着反应时间的增加而增加。但当反应温度和反应时间超过某值时接枝率和接枝效率反而下降。接枝侧链聚甲基丙烯酸甲酯具有较高的分子量(～10~5)。     

聚乙烯辐照接枝体系改变pH对接枝率的影响

采用γ射线辐照引发接枝的方法，在高密度聚乙烯（HDPE）上接枝丙烯酸（AA）和对接枝苯乙烯磺酸钠（SSS），制备了一种含羧酸基团和磺酸基团的阳离子交换膜，详细研究了反应体系在不同pH值下的接枝率变化规律。实验表明，在共辐照接枝方法中，当AA与SSS一步法接枝HDPE或接枝上AA的HDPE膜再共辐照接枝SSS时，总接枝率（Gt）及对苯乙烯磺酸钠的接枝率（Gs）随体系的pH的降低而升高，在预辐照一步法接枝中，Gt与Gs随体系pH的降低先升高后又有所降低，综合分析认为，改变pH值使体系粘度发生变化，从而影响了单体向基体的扩散速率。     

取向聚四氟乙烯接枝丙烯酸共聚物的形态结构和性能研究

用光学显微镜，电子显微镜，Ｘ射线衍射等方法对不同拉伸度聚四氟乙烯（ＰＴＦＥ）和对其γ辐射接枝丙烯酸（ＡＡ）接枝共聚物的结构进行了研究，结果表明，未接权取向的ＰＴＦＥ，在γ射线辐射下产生大小不等的空穴，接枝丙烯酸填充在这些空穴中，形成粒状分散相微区结构，接枝量增大形成接枝链束，而使双折射增加，并对接枝共聚物和性能关系进行了讨论。     

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。     

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。     

NIPAAm在棉纤维织物上预辐射接枝共聚机理研究

研究了温度敏感性聚合物Ｎ－异丙基丙烯酰胺在棉纤维织物表面预辐射接枝共聚反应,给出了吸收剂量,剂量率,单体浓度,接枝反应温度等对接枝率的影响,着重讨论了接枝共聚反应机理,证实了对接枝共聚反应起主要作用的陷落自由基是处于纤维素无定型区和结晶区交界的第三相,部分接枝链嵌入相邻结晶区使纤维结晶区含量随接枝率增长而下降。实验还证实除了陷落自由基外,在空气中辐照时样品无定型区生成的过氧化物随接枝反应温度的升高     

铬鞣绵羊皮辐射接枝丙烯酸丁酯的成革性能

脱灰裸皮和铬鞣绵羊皮在~(60)Co-γ射线引发下,能与丙烯酸及丙烯酸丁酯发生接技共聚反应,我们曾报道过通过测定氮含量、茚三酮显色试验和红外光谱分析得以确证。本文报道云贵路绵羊皮辐射接技丙烯酸丁酯的成革性能。 云贵路绵羊皮皮板瘦薄,痘疔、癣癞及伤残较多,毛孔大,粒面粗糙,部位差异大,是国内最次的原料皮。用这种低档原料皮来生产中、高档服装手套革显然是困难的。成革等级     

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.