水溶性超高分子量聚丙烯酸胺的辐射反相乳液合成

用＾６０Ｃｏγ射线引发丙烯酰胺反相乳液聚合，研究了吸收剂、剂量率、乳化剂含量和单体含量及辐射后效应对聚丙烯酰胺分子量的影响，特别是采用高剂量率引发，特低剂量率辐射聚合的手段，不仅提高了产物分子量，缩短聚全时间，而且提高了转化率，防止了聚合物的交联。     

丙烯酰胶-乙醇体系辐射反应的研究

本文介绍了在乙醇介质中用~(60)Coγ射线辐射引发聚合合成纯度较高的聚丙烯酰胺(PMA),并对它的辐射聚合动力学进行了研究。结果表明:在乙醇介质中丙烯酰胺(AM)辐射聚合转化率随着反应体系的温度、剂量率及单体浓度的增加而增加,但聚合物分子量却随着反应体系温度的增加而略有下降。此外,计算了本体系的表观活化能为7.56kJ/mol(1.88kcal/mol)。     

辐射聚合的进展

辐射聚合是高分子辐射化学中研究得最早和最多的一个方面。1925～1967年,研究过的单体已超过350种。七十年代以来,研究的范围不断扩大和深入,取得了很大进展,其中最主要的有两个方面:一是脉冲辐解技术用于辐射聚合的基本理论研究,由于可以直接观测中间产物的形成、变化和归宿,这就可能弄清楚长期来只处于推论或难以证明的聚合机理,以期从根本上解决辐射聚合的规律;二是充分利用电离辐射的特点,开发新的辐射聚合技术和工艺。例如辐射聚合的引发活化能趋近于零,聚合可在较低温度下进行,从而开发出过冷态辐射聚合的崭新工艺;又如辐射产生的活性基均匀地分布于整个体系,由此出现了各种晶态固相聚合方法;再如由外部射线的能量引发体系内部进行聚合,可以容易地调节剂量、剂量率而控制聚合的进程、分子量及分子量分布,这就发展出不同的催化-辐射控制聚合法等。本文重点介绍晶态固相、过冷态、高剂量率和催化-辐射控制聚合的进展。而预辐射聚合、乳化聚合、介质敏化聚合等也有不少新的发展,恕不赘述。     

丙烯酰胺中浓度水溶液的辐射聚合——EDTA二钠体系的研究

本文研究了用~(60)Coγ射线引发丙烯酰胺水溶液的聚合体系中,添加乙二胺四乙酸二钠盐(EDTA),对提高聚合物分子量,改善水溶性和掩蔽铜、铁等有害杂质的作用。同时也对剂量率、剂量、辐照温度等因素进行了探讨。制得了分子量高,水溶性好的聚丙烯酸胺(PAM)。本实验结果为中间试验和工业化生产提供了科学依据。     

亚麻油氧化预聚和辐射聚合的研究

研究了亚麻油氧化预聚中性质的变化以及辐射聚合中吸收剂量，剂量率，环烷酸钴帮三羟甲基丙烷三丙烯酸酯（ＴＭＰＴＡ）对预聚亚麻油辐射聚合的影响以及协同效应，结果表明，亚麻油在氧化预聚过程中，体系的活性氧含量，碘值，特性粘度和酸值等性质都是发生了相应的变化，在辐射聚合中，体系的碘值随着吸收剂量的提高而下降，在吸收剂量相同的条件下，剂量率越高，凝胶含量也越高；环烷酸钴对预聚亚麻油辐射聚合有一定的促进作用，且     

硫代苯甲酸存在下辐射引发活性自由基聚合

在二硫代苯甲酸(PhCSSH)存在下，用^60Coγ射线辐射引发苯乙烯(St)、甲基丙烯酸丁酯(BMA)聚合，采用核磁共振氢谱(^1HNMR)和凝胶渗透色谱(GPC)对聚合物结构和聚合物的分子量及其分子量分布进行表征。结果表明，在PhCSSH存在下，由辐射引发St、BMA聚合具有活性聚合特征：聚合物具有较窄的分子量分布，分子量随转化率线性增加，聚合物分子链中含有活性端基。并对聚合机理进行了探讨。     

P(NIPA-co-HEMA)与PNIPA/P(HEMA)IPN水凝胶的辐射聚合与可控缓释研究

采用辐射聚合方法制备了聚N-异丙基丙烯酰胺(PNIPA)均聚物、N-异丙基丙烯酰胺(NIPA)与甲基丙烯酸2-羟基乙酯(HEMA)共聚物(P(NIPA-co-HEMA))和PNIPA/P(HEMA)互穿网络(Interpenetrating Polymer Network,IPN)水凝胶。研究了水凝胶溶胀度的温度依赖性;讨论了剂量率和吸收剂量对辐射聚合的影响,单体浓度及其配比和聚合介质对水凝胶的相转变温度、溶胀度和溶胀一消溶胀动力学的影响;并以木瓜蛋白酶作为模型药物,对水凝胶进行药物释放测定。实验结果表明,较为适宜的水凝胶在剂量率1kGy／h,吸收剂量30—40kGy,单体浓度10％和聚合介质正丁醇中辐射合成。此类共聚与互穿网络水凝胶适用于药物的可控释放。     

氢氧化钠和氮川三丙酰胺对丙烯酰胺γ射线辐射聚合的影响

本文研究了在~(60)Co γ射线作用下,分别用氢氧化钠和氮川三丙酰胺[N(CH_2CH_2CONH_2)_3]水溶液作为添加剂,对丙烯酰胺(简称AM)辐射聚合的影响。通常控制氢氧化钠含量在0.34—0.72％,吸收剂量为(1.1—3.3)×10~4拉德,可以得到水溶性好、分子量5×10~6左右的聚丙烯酰胺(简称PAM)。用氮川三丙酰胺水溶液作为添加剂,在聚合体系中其含量在1.5—2.5％范围内,可以得到水溶性好,分子量3×10~6以上的PAM;含量低于上述范围则出现交联不溶物;超过3％,分子量明显降低。在我们的实验条件下,在加入氨水的AM反应体系中,得到了氮川三丙酰胺结晶,而在氢氧化钠的AM体系中,未得到氮川三丙酰胺结晶。核磁共振波谱表明,氢氧化钠0.53％,AM67％的体系,在室温下氮川三丙酰胺生成量约0.06％。本文还讨论了AM辐射聚合过程中聚合链的氢自由基H交联机制。     

蚕丝绸预辐射接枝甲基丙烯酰胺研究

为了提高丝绸产品的质量,对蚕丝绸辐射接枝化学单体的原理和方法进行了更深入地研究。采用预辐射接枝方法将甲基丙烯酰胺单体接枝于蚕丝绸上,研究了接枝率与预辐射剂量、剂量率、接枝反应时间、单体浓度和样品含水量等的关系。此外,讨论了预辐射接枝反应机理;对蚕丝绸预辐射接枝法与辐射固相接枝聚合方法进行了比较,显然,预辐射接枝方法有许多优点,它可实现蚕丝纤维的表面接枝,适合于改善丝绸的染色性能,以及应用于丝绸     

水溶性的温度敏感性聚合物、活性共聚物的辐射合成及性质研究

研究了Ｎ－异丙基丙烯酰胺（ＮＩＰＡＡｍ）在水溶液及四氢呋喃溶液中的辐射聚合及它与活性有机单体Ｎ－丙烯酰氧基丁二酰亚胺（ＮＡＳＩ）辐射共聚，以制备水溶性、温度敏感性均聚物及共聚物。结果表明，室温、无氧条件下在水或ＰＢＳ缓冲溶液中ＮＩＰＡＡｍ及它与ＮＡＳＩ共聚物（ｐｏｌｙＮＩＰＡＡＭ－ＮＡＳＩ）辐射合成的最佳条件为：剂量１－７ｋＧｙ，剂量率不小于４０Ｇｙ／ｍｉｎ，溶液中单体浓度小于１％。单体在四氢呋喃中辐射聚合可得到粉末状固体聚合物。将这种聚合物溶于水中仍具有温度敏感性，用此法可获得较多的此类聚合物，只是分子量偏低（Ｍｎ只有１０４数量级），其合成条件与在水溶液中也有较大差异。该聚合物经热性质测定表明，多次溶解、沉淀后仍能保持其热性质的均一性和稳定性。     

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.     

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.     

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.