基于同步辐射的直接硼氢化钠燃料电池中阴极催化剂的原位测试装置

介绍了上海光源硬X射线微聚焦及应用线站的新型原位实验装置,可用于对直接硼氢化钠燃料电池(DBFC)中阴极催化剂进行原位X射线衍射和荧光模式的X射线吸收近边结构测试,为研究阴极催化剂催化氧还原反应(ORR)机理提供实时表征依据。为验证本原位装置的可行性,在DBFC(采用聚吡咯修饰的碳载氢氧化钴作为阴极催化剂)工作过程中对催化剂进行原位测试。结果表明,在DBFC放电过程中,催化剂中Co元素的价态和局域结构发生变化,催化反应过程中新相形成。表明该原位实验装置对于DBFC中阴极催化剂催化ORR机理的研究是可行的。     

同步辐射EDXAFS和EDXRD联用方案

许多材料研究中,都需要采用X射线吸收精细结构谱学(X-ray Absorption Fine Structure,XAFS)和X射线衍射(X-ray Diffraction,XRD)技术测量材料的短程和长程有序结构信息,而如何同时快速地测量是开展原位动态研究的一个关键。本文提出了一种结合能量色散X射线吸收精细结构谱(Energy-dispersive X-ray Absorption Fine Structure,EDXAFS)和能量色散X射线衍射(Energy-dispersive X-ray Diffraction,EDXRD)的测试方案,该方案利用同步辐射白光,理论上可以提供微秒量级的表征速度和时间分辨能力,为真实环境下材料结构的原位实时表征提供了一种可能方法。     

纳米晶BaTiO3的高压研究

采用原位高压同步辐射X光衍射技术和Raman散射方法，对小于临界尺寸（120nm)的纳米晶BaTiO3(48nm)进行了研究，在实验压力范围内（0－21．2GPa,0-46.67GPa)，纳米晶BaTiO3始终处于稳定的立方相。     

20 Hz高时空分辨X射线单色光动态显微CT研究

与白光X射线动态显微CT(Micro Computed Tomography)相比,单色光X射线动态显微CT具有较低的辐射损伤和较高的密度分辨率,但是更难以平衡其空间和时间分辨率。目前,单色光X射线动态显微CT的最高时间分辨率可达到13.3 Hz,探测器有效像素尺寸为5μm。为了构建具有更高时空分辨率的单色光X射线动态显微CT系统,基于上海光源快速X光成像线站（BL16U2）的高通量密度单色光,将高速转台与三镜头大数值孔径快速X射线成像探测器相结合,构建了实验系统。以速发型聚氨酯材料为研究对象进行了验证实验,在15 keV单色光下动态显微CT的时间分辨率达到了20 Hz,探测器有效像素尺寸为2.2μm。对气泡运动进行相关定量分析,证明该系统具有高时空分辨率和高对比度分辨率,可以对复杂运动系统进行四维时空定量分析,为BL16U2线站用户进行高时空分辨率的复杂原位研究提供了强大的实验平台。     

滤波差分法测量软X光谱

研究了一种测量激光等离子体发射软X光谱强度的新方法——滤波差分法。文中介绍了滤波差分法基本原理,给出了滤波差分对的理论计算结果及实验测量结果,并用此方法获得软X光谱的绝对强度,最后对测量光谱强度的误差进行分析和估算。滤波差分法建立在以往滤波法测量软X光能谱的基础上,利用软X光能谱仪(Dante谱仪)的十个探测道,采取滤波差分法构成两两配对的五个差分对。设计匹配差分对,使其上下K边或L边之外的能响互相抵消,从而使差分对切割能谱,能基本消除高能尾部对所测能区的贡献,提高能谱测试系统的单色性,提高能谱的反演精度,从而建立滤波差分法测量软X光谱的系统。     

应用于PandaX-Ⅲ实验探测器测试平台的Bulk Micromegas性能研究

探测无中微子双贝塔衰变的PandaX-Ⅲ实验需要一个能同时对多个Micromegas探测器的增益、能量分辨、坏道分布、位置分辨等性能参数进行测试的平台,为此中国原子能科学研究院建立了PandaX-Ⅲ实验探测器测试平台。本文采用由光蚀刻技术制作的Bulk Micromegas对该测试平台进行研究:利用~(55)Fe放射源在Ar+10%CO_2的流气情况下,使用基于AGET读出芯片制作的通用读出电子学进行数据采集;运用C++与ROOT软件库编写相应的后端数据分析软件,并对数据进行了分析。测试结果表明,PandaX-Ⅲ实验探测器测试平台各系统工作状态良好,应用于测试平台的Bulk Micromegas探测器具有良好的信噪比,X射线成像效果清晰,对5.9 keV X射线的能量分辨率为19.7%。     

缝靶X光辐射特性诊断技术研究

在“星光Ⅱ”激光装置上,采用长柱缝靶模拟X光在柱腔内的输运过程,研究腔壁X光的辐射特性。实验中利用高时空分辨的X射线皮秒分幅相机和软X射线条纹相机从缝口观测腔内壁X光辐射时空分布,得到X光在腔中的输运速率、X光发射时间和轴向强度衰减量。利用X射线CCD针孔透射光栅谱仪观测到腔内X光辐射光谱随空间位置的变化,得到X光在输运过程中被多次吸收和发射后谱的变化特征。用XRD和Dante谱仪分别得到缝口、源和输运末端X光辐射总量和辐射温度。给出了实验中获得的典型结果,并对获得的结果进行了简要的分析讨论。     

整体X光透镜在X射线衍射应用中的新进展

介绍了整体X光透镜的物理性能。使用X光透镜进行了生物大分子晶体衍射实验,结果表明:在相同X光源功率条件下,衍射强度提高了近7倍,大大缩短了测试时间,分辨能力改善0.2×10~(-10)～0.6×10~(-10)m,信噪比也有改善。在粉末衍射仪上,进行了Si(100)衬底上金薄膜的衍射实验,结果表明:在相同X光源功率条件下,使用X光透镜后的衍射强度提高了近2倍,同时改善了衍射仪的角分辨率。     

光电转化器件光阴极量子效率测量研究

光电器件(光电倍增管、光电二极管、太阳能电池等)的应用研究日益广泛,对其性能的测试要求也越来越高,尤其是对其核心部件光阴极光电转化量子效率(Quantum efficiency,QE)的测试和标定。通过建立的光阴极性能测试系统,开展了对各种型号光电器件阴极的测试研究。测试研究内容包括对光阴极在特定波长下QE的绝对测量和相对测量、对光阴极频谱响应特性的测量以及对光阴极面均匀性的扫描测试。目前对多种不同型号的光电二极管(Photo diode,PD)和光电倍增管(Photomultiplier tube,PMT)光阴极QE的测试结果显示,无论采用绝对测量或相对测量,其结果均与已有第三方标定结果一致;同时,搭建的二维扫描测试平台实现了对平面型光阴极均匀性的快速准确测试。     

缝靶X光辐射特性诊断技术研究

在“星光Ⅱ”激光装置上, 采用长柱缝靶模拟 X 光在柱腔内的输运过程,研究腔壁 X 光的辐射特性。实验中利用高时空分辨的 X射线皮秒分幅相机和软 X射线条纹相机从缝口观测腔内壁 X光辐射时空分布,得到 X 光在腔中的输运速率、X 光发射时间和轴向强度衰减量。利用 X 射线 CCD 针孔透射光栅谱仪观测到腔内 X 光辐射光谱随空间位置的变化,得到 X 光在输运过程中被多次吸收和发射后谱的变化特征。用 XRD 和 Dante 谱仪分别得到缝口、源和输运末端 X 光辐射总量和辐射温度。给出了实验中获得的典型结果,并对获得的结果进行了简要的分析讨论。     

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.