Al-Si共晶合金与1Cr18Ni9Ti不锈钢的相容性研究

用粉末冶金法制备了Al-Si共晶合金与1Cr18Ni9Ti不锈钢反应堆扩散偶。采用电子显微镜（SEM）、能谱分析仪（EDS）、X射线衍射仪（XRD）D究了扩散偶在560℃和650℃时的相容性及扩散层形成机理。结果表明，扩散温度对两种材料之间的相容性有显著影响；650℃时，Al-Si共晶合金与1Cr18Ni9Ti之间通过浸润和扩散反应形成了比较明显的扩散层。XRD谱也表明，扩散层中存在Fe2Al5化合物；560℃时Al-Si共晶合金与1Cr18Ni9Ti之间仅发生固相反应，形成的扩散层很薄，二者相容性较好。     

U-Mo合金与Zr-4合金的扩散层性质研究

本文对U-Mo合金与Zr-4合金的扩散层性质进行了研究。三明治结构的U-Mo/Zr-4扩散偶在760~800℃下包覆热轧后,保温10~66 h。采用扫描电子显微镜(SEM)分析了扩散层的形貌和厚度,采用波谱仪(WDS)分析了各元素在扩散区内的分布情况,采用X射线衍射仪(XRD)测定了扩散层的相组成。分析结果表明,即使在800℃的高温下,U-Mo/Zr-4的扩散程度依然微弱,表现出良好的相容性;U-Mo/Zr的扩散层中间出现裂纹,裂纹两侧的扩散层相组成明显不同,靠近U-Mo侧为富Mo相,其主要是以化合物ZrMo_2为基的固溶体;靠近Zr-4侧的为富Zr相,其主要是以化合物UZr_2为基的固溶体;裂纹认为是由U和Zr不等量的原子交换所造成的。     

U-Mo合金与Zr合金的相容性研究

采用扩散偶方法研究U-Mo合金与Zr的相容性。扩散偶采用包覆热轧法制备,热处理温度为750℃和800℃,热处理时间为10 h和50 h。结果表明:U-Mo合金与Zr合金间的扩散层有分层现象,在U-Mo/Zr界面扩散反应成分复杂界面处存在类似Mo2Zr的析出物。经X射线衍射(XRD)检测表明U-Mo/Zr扩散层由M2Zr、UZr2和U等组成。U-Mo/Zr的扩散过程是U和Mo原子向Zr扩散,Mo优先与Zr反应生成Mo2Zr、U通过Mo2Zr扩散形成γ-(U,Zr)固溶体的过程。U-Mo合金与Zr具有良好的相容性。     

U-10Mo/Al-Si固体扩散行为

采用扩散偶方法研究U-10Mo合金与Al-xSi(x＝0，1，2，5，7，9，质量分数)合金的固体扩散行为。实验在真空热压炉中完成，退火温度为555、570、580、590和595℃，时间为5～10h。实验结果表明：退火条件对扩散行为有显著影响，580℃是U-10Mo/Al-xSi扩散行为的重要分界点；当温度低于580℃热压退火处理时，扩散层厚度随Si含量的增加先急剧减小然后缓慢增大；当温度高于580℃时，扩散层的厚度随Si含量的增加而增加。Si含量较高(≥2%)的扩散偶扩散层厚度比低Si含量的小，扩散层呈3层结构，靠近Al-Si侧出现贫Si区。成分分析显示：Si含量较高的扩散偶，靠近U-Mo侧的扩散薄层中出现Si的富集，其成分为(U，Mo)(Al，Si)_x (x≤3)；靠近Al-Si合金侧的扩散层成分为(U，Mo)(Al，Si)_x (x＞3)。     

U-10wt%Mo合金与LT24Al的反应层性质研究

对U-10wt%Mo合金和LT24Al合金的反应层性质做了较详细的研究.将U-Mo/Al扩散偶试样在不同条件下进行热压处理,用光学显微镜(OM)和扫描电子显微镜(SEM)分析反应层的厚度,用能谱仪(EDS)分析各元素在反应区内的分布情况,用X射线衍射仪(XRD)测定了反应层的相组成.分析结果表明:U-Mo合金与Al的扩散方式是反应扩散,方向主要为Al原子通过空位扩散向U-Mo合金中迁移;反应层生长动力学表明反应为扩散所控制;U-Mo/Al的单相反应层主要由(U, Mo)Al3组成;两相或多相反应层主要由(U, Mo)Al3和(U, Mo)Al4组成,此外还含有Al20Mo2U;Al中的杂质Si容易在反应层中富集,这种趋势说明Si对改善U-Mo合金和Al的相容性起积极作用.     

奥氏体321不锈钢在550 ℃静态铅铋共晶合金中的腐蚀行为

奥氏体321不锈钢常用作核反应堆冷却剂主管道结构材料，铅铋共晶合金是第四代核能系统（Gen Ⅳ）铅冷快堆冷却剂的主要候选材料。为研究321不锈钢与高温液态铅铋共晶合金的相容性，对321不锈钢在550 ℃液态铅铋共晶合金中的200、400、600 h腐蚀现象进行了研究。对不同腐蚀时间后腐蚀试样的表面和截面分别进行了XRD和SEM、EDS检测。结果发现：在321不锈钢试样表面产生了一种随腐蚀时间增加先生长后脱落的含O、Ti、Pb元素的化合物（Ti₂O和Pb₂O₃）；在321不锈钢基体与铅铋共晶合金交界处会产生一层随腐蚀时间增加不断增厚的扩散层；321不锈钢在铅铋共晶合金中发生溶解腐蚀，在Fe、Cr元素不断向铅铋共晶合金中溶解时，伴随着Pb、Bi元素向基体中的渗透。     

U-Mo合金与Al扩散反应特征研究

采用扩散偶方法研究了U-Mo合金与Al扩散反应特征.扩散偶以热压方式实现持续贴合.实验在真空热压炉中完成,热压温度550-570℃,时间5～21 h.结果表明:U-Mo/Al扩散层界面形貌和成分与扩散层厚度有关;在扩散层界面处U、Mo和Al的含量突变;U-Mo侧扩散层产物主要为(U,Mo)Al3,Al侧产物为(U,Mo)Al4和UMo2Al20.U-Mo/Al扩散反应是Al越过U-Mo/Al原始界面向U-Mo侧扩散并发生固体反应和扩散层向Al层生长的过程.     

新型高温锆合金在过热蒸汽中的腐蚀性能

研究了不同含量的Zr-Fe-Cr合金的显微组织及其在500℃,10.3 MPa 过热蒸汽中的耐腐蚀性能.结果表明,Zr-Fe-Cr合金经过真空熔炼、β淬火、真空包覆热轧和冷轧,以及真空退火处理得到的组织主要为α-Zr基体和弥散分布的Zr(Cr,Fe)2粒子.在500℃,10.3 MPa 过热水蒸汽中,含有少量合金元素的Zr-0.2Fe-0.1Cr和Zr-4合金会发生疖状腐蚀,而含有适当Fe、Cr的Zr-Fe-Cr合金为均匀腐蚀.Zr-1.0Fe-0.6Cr合金耐蚀性最好,其耐过热蒸汽腐蚀能力优于N18和Zr-4合金;含Fe、Cr元素不同的锆合金试样由于成分不同,耐腐蚀性能也有明显差别,说明调整合金成分是改善锆合金在500℃,10.3 MPa 过热蒸汽中耐腐蚀性能的主要途径.     

U-Mo合金与Nb的互扩散行为

采用包覆热轧法制备U-Mo/Nb固相复合扩散偶，在760℃下对U-Mo/Nb固相复合扩散偶进行不同时间（3～15h）的扩散热处理，得到了不同厚度的扩散层。对热处理时间与扩散层厚度间的关系进行了线性拟合，观察到扩散层生长起初具有一段孕育期。对热处理后扩散层进行了SEM分析和EDS分析，初步讨论了扩散偶长时间热处理后靠近U-Mo合金一侧出现裂纹的原因。对扩散偶热处理后扩散组元分布进行了深入分析，观察到长时间的热处理扩散层厚度的增加只是U元素在Nb基体中的均匀化过程。     

Zr-4合金铸锭化学成分的控制

按照合金元素在真空自耗电弧熔炼过程中的行为特征、受到的影响因素和控制方法的不同,将Zr-4合金中的24种元素分为工艺控制元素、工艺保证元素和由海绵锆决定的元素三类。主合金元素Sn,Fe,Cr,以Zr-Sn-Cr-Fe中间合金的形式,在压制电极块时加入到海绵锆中,氧以金属氧化物的形式加入,并建立了在加入金属氧化物的Zr-4合金的配料公式。通过对250炉Zr-4合金铸锭分析试验表明,铸锭化学成分是均匀的,它们的标准偏差为:σ_(Sn)=0.072％,σ_(Cr)=0.0064％,σ_(Fe)=0.014％,σ_(o_2)=0.017％。对φ<220mm纵剖试验表明,Sn,Fe,Cr,O_2,在铸锭内部具有良好的均匀性。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

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。     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

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.     

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.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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Radioactivity levels in soil of salt field area,Kelambakkam,Tamilnadu,India

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer.The activity concentration for ~(232)Th,~(238)U and ~(40)K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg,and from 135.54 to 381.28 Bq/kg,respectively.The measured activity concentrations for these radionuclides were compared with world average activity of soil.The average activity concentration of ~(232)Th in the present study is 1.19 times higher than world median value while the activity of ~(238)U and ~(40)K is found to be lower. The absorbed dose rates due to these radionuclides were calculated.The average absorbed gamma dose rate due to the presence of ~(232)Th,~(238)U and ~(40)K in soil samples is 36.99 nGy·h~(-1).These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.