预辐射聚丙烯纤维接枝N-异丙基丙烯酰胺及其对Fe(Ⅱ)离子的吸附

采用预辐射接枝法，将N-异丙基丙烯酰胺（N-Isopropylacryamide，NIPAAm）接枝于聚丙烯纤维。研究了不同条件下接枝纤维对亚铁离子的吸附和解吸附情况。结果表明，在较低温度（5℃）及pH≈10条件下，接枝纤维对金属离子（Fe^2＋）具有良好的吸附性能；而在较高温度（50℃）下pH≈3时，被吸附的Fe^2＋几乎能被较完全解脱下来。     

预辐照接枝丙烯酸与丙烯酰胺改性苎麻纤维及其吸附铜离子性能研究

将丙烯酸(AA)与丙烯酰胺(AM)通过预辐照接枝在苎麻纤维上,通过协同作用提高其接枝率,并研究了其对Cu2+的吸附性能。傅里叶红外光谱(FT-IR)对苎麻纤维表面分析结果显示,AA及AM成功接枝在苎麻纤维上,吸收剂量为35kGy时,接枝率可达151%(AA与AM浓度比为1∶1)。对Cu2+的吸附实验结果表明,接枝后的苎麻纤维在吸附反应初期,Cu2+吸附量迅速增加,20~30min增加速度变缓,30min后趋于饱和;随着温度升高,吸附量迅速增加,但温度高于40℃后,吸附量不再增加;吸附量随初始Cu2+浓度的增加而增大,在初始浓度为1 000mg/L的Cu2+溶液中,苎麻纤维的Cu2+吸附量可达14.40mg/g。     

99Tc在Fe,Fe2O3和Fe3O4上的吸附行为研究

用批式法研究了大气条件下99Tc在Fe,Fe2O3和Fe3O4上的吸附行为,考察了吸附平衡后溶液中99Tc的存在价态.实验结果表明随着溶液pH值(5～12)、CO2-3浓度(1×10-8～1×10-2 mol/L)的增大,99Tc在Fe上的吸附比减小;溶液pH值、CO2-3浓度的变化基本不影响99Tc在Fe2O3和Fe3O4上的吸附;99Tc在这3种吸附材料上的吸附行为均可用Freundlich吸附等温式表示;当Fe作吸附材料时,吸附平衡后99Tc主要以Tc(Ⅳ)的形式被吸附,当Fe2O3和Fe3O4作为吸附材料时,99Tc主要以Tc(Ⅶ)的形式被吸附.     

99Tc在膨润土中的吸附和迁移行为

在模拟处置库条件下,采用北山地下水,用批式实验法研究了99Tc在内蒙古高庙子膨润土中的吸附行为,探讨了温度、pH值,添加剂黄铁矿(FeS2)、磁铁矿(Fe3O4)、方铅矿(PbS)、稀土赤铁矿(Fe2O3),以及CO2-3、SO2-4、Fe2+、Fe3+等对吸附行为的影响.研究结果表明,高庙子膨润土对99Tc具有一定的...     

铀在木纤维上的吸附行为及机理分析

为了解木纤维对铀的吸附特性,通过静态吸附实验,研究了木纤维的粒度、吸附时间、用量、温度及溶液的pH值和初始浓度等因素对模拟含铀废水中U(Ⅵ)去除率的影响,并从热力学和动力学方面对吸附过程进行了分析。结果表明:溶液初始pH≈3时,木纤维对铀的吸附平衡时间为4h,且吸附剂粒径越小、温度越高、用量越大,越有利于铀的去除;铀在木纤维上的吸附过程符合Langmuir等温吸附方程,吸附动力学过程可用准二级吸附动力学模型描述,表明化学吸附主要受动力学控制;木纤维吸附铀是自发的吸热反应。SEM、FT-IR和EDS分析结果表明,木纤维吸附铀后表面形态发生了改变,且在吸附过程中铀主要与木纤维表面活性基团螯合并形成配合物,存在表面络合吸附行为;吸附铀前后的能谱对比分析表明,吸附过程中存在离子交换行为。因此,木纤维对铀的吸附机理是以离子交换和表面络合吸附为主、物理吸附为辅的混合吸附过程。     

聚丙烯胺肟螯合纤维的辐射合成及其对Pb(Ⅱ)离子的吸附性能

采用预辐照接枝法,在空气或氮气气氛下利用电子束对聚丙烯纤维进行辐照。然后,将样品置于4种不同溶剂(水、甲醇、正丁醇、10％甲醇水溶液)的丙烯腈溶液体系中进行接枝反应,并通过与盐酸羟胺溶液反应,引入胺肟基团,获得一种机械性能较好的偕胺肟螯合纤维(PPAO)。最后浸于硝酸铅标准溶液中,测定其对铅的吸附量。结果表明,接枝率与预辐照气氛、反应温度、反应液体积、单体浓度都有密切关系。聚丙烯纤维在水溶液和10％甲醇水溶液中接枝率较高。当纤维在空气中预辐照,丙烯腈单体体积浓度为30％,温度为70℃时,聚丙烯纤维的接枝率最高;对Pb(Ⅱ)的吸附容量为0．362mg／g(纤维)。     

含有季铵盐的超高分子量聚乙烯纤维对 Au（III）的吸附效应

利用预辐射接枝技术制备含有季铵盐官能团的超高分子量聚乙烯(UHMWPE-g-P(GMA-co-MA)-TETA- GTA)纤维。研究该纤维对Au(III)的吸附性能,重点考察了起始溶液的pH值、初始Au(III)离子浓度和温度对吸附容量的影响。实验结果表明,UHMWPE-g-P(GMA-co-MA)-TETA-GTA 纤维对 Au(III)的吸附速率较快、吸附容量大,180 min内能够达到吸附平衡;在溶液的pH值为3时吸附容量最大(355 mg/g)。该吸附过程符合准二级动力学模型和和Langmuir等温吸附模型,吸附反应是一个熵减少的放热反应。     

裂片核素的迁移研究 Ⅰ.混凝土对碘的吸附

研究了在模拟地下水介质中,混凝土对碘的吸附(解吸)规律和吸附等温线。实验表明,在30±2℃、c_I=10~(-6)mol/l、pH=9.01条件下的分配比R_(D_a)=3.16±0.32ml/g。还对酸度、固液比、固体比表面和还原剂Fe、(NH_2)_2存在时对R_D值的影响进行了研究。     

99Tc在Ca-基膨润土中的吸附行为

用批式法研究了99Tc在Ca-基膨润土中的吸附行为.大气条件下,99Tc在膨润土中的吸附比约为1.47 mL/g,随着溶液pH值、CO2-3、Fe3+浓度的增大,99Tc在膨润土中的吸附比基本不变;随着添加剂Fe2O3和Fe3O4加入量以及Fe2+浓度的增大,99Tc在膨润土中的吸附比增大,吸附平衡后,99Tc主要以Tc(Ⅶ)的形式存在;随着添加剂Fe加入量的增大,99Tc在膨润土中的吸附比增大,吸附平衡后,99Tc主要以Tc(Ⅳ)的形式存在.低氧条件下,99Tc在膨润土中的吸附比约为84.84 mL/g,随着溶液pH值、CO2-3浓度的增大,99Tc在膨润土中的吸附比减小;随着溶液Fe2+、Fe3+浓度以及添加剂Fe、Fe2O3和Fe3O4加入量的增大,99Tc在膨润土中的吸附比增大,低氧条件下99Tc主要以Tc(Ⅳ)的形式存在.大气与低氧条件下,99Tc在膨润土中的吸附行为均可用Freundlich吸附等温式表示.     

β-环糊精改性介孔二氧化硅材料对U（Ⅵ）的去除机制

以三乙氧基(3-异氰酸丙基)硅为交联剂,通过后接枝法合成了β-环糊精改性介孔二氧化硅（SBA-15-CD）材料。通过静态吸附试验研究了溶液pH值、SBA-15-CD投加量、吸附时间、温度等因素对SBA-15-CD吸附U(Ⅵ)的影响。通过扫描电镜（SEM）、X射线粉末衍射（XRD）、BET比表面分析、傅里叶红外光谱（FT-IR）和X射线光电子能谱（XPS）对材料进行表征分析,并探讨了SBA-15-CD吸附U(Ⅵ)的机制。结果表明,当U(Ⅵ)初始浓度为5 mg/L、温度为30 ℃时,SBA-15-CD吸附U(Ⅵ)的最佳条件为:pH=5、SBA-15-CD投加量0.20 g/L、吸附平衡时间30 min,在此条件下,平衡吸附量为24.4 mg/g,U(Ⅵ)去除率为98.3%。吸附过程符合准二级动力学模型和Langmuir等温模型,即以化学吸附为主,且主要是通过表面的羟基、酯基和氨基与U(Ⅵ)配位。30 ℃下SBA-15-CD的饱和吸附量达330 mg/g,升高温度有利于吸附的进行。SBA-15-CD具有良好的重复使用性能。     

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.     

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.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.