Mo含量对Ti-Mo合金氢同位素效应的影响

采用磁悬浮熔炼法制备了固溶体合金TiMox（x=0．03、0．13、0．25、0．50、1．00,x为Mo与Ti原子数之比）,经活化后与H—D混合气（D原子占50％）反应,反应平衡后用质谱分析气相中H和D的含量。根据反应前气相中H和D的含量,由质量守恒定律求得固相中H和D的含量。根据气、固两相中的氕氘原子数之比（D／H）,由公式α（H-D]=（ED3／[H]）（目目）／（ED3／[H]）（气相）计算得到H-D分离因子α（H-D）。结果表明：20℃下,x0．03～1．00时,α（H-D）〉1．00,合金氢化物表现为正同位素效应。随着Mo含量的增加,α（H—D）由1．04增加到1．27;x〉0．50时,α（H-D）基本保持不变。2／7—0．03时α（H-D）≈1．00,合金表现为零同位素效应。根据以前热分析实验结果,TiMo0.03吸氢后析出大量负同位素效应的TiH2,并有少量正同位素效应的Ti—Mo合金氢化物,零同位素效应是两者共同作用的结果。根据Mo含量和分离因子的关系,室温下H原子倾向于占据4Ti四面体间隙位置,而D原子倾向于占据能量较高的3TilMo四面体间隙位置。     

钒合金的氢致硬化和氢脆

通过气相渗氢后的室温拉伸试验,测试了多种钒合金材料的拉伸性能,如V-4Ti、V-6W-lTi和V-4Cr-4Ti,以及日本国立核聚变研究所研制的V-4Cr-4Ti合金,研究了钒合金的氢脆行为及其影响因素.实验结果表明钒合金有较强的吸氢能力,合金元素Ti能显著提高合金的吸氢量.在达到氢致脆性断裂前,氢致强化表现为典型的固溶强化,而其强化能力因Ti的存在而显著降低,是含Ti钒合金具有优良抗氢脆性能的主要原因.合金氧含量极大地影响合金的抗氢脆能力.氧含量在200～400 μg/g时,V-4Cr-4Ti合金发生氢脆断裂的临界氢含量约为300 μg/g,而当氧含量超过700 μg/g时,该临界值低于50 μg/g.另一方面,强度较低的V-4Ti合金似乎具有更好的抗氢脆能力.     

Ti-Mo互扩散界面吸氢同位素效应的离子束分析研究

为探究Ti-Mo互扩散对金属吸氢的影响,本文采用离子束分析方法对Ti-Mo薄膜的膜-基互扩散界面的吸氢同位素（H和D）效应进行了研究。通过氩离子刻蚀减薄的方法有效降低了表面碳、氧杂质对样品吸氢的影响。吸氢结果表明,对于表面洁净的样品,氢化后固相中氢或氘的浓度均沿着深度随钼原子含量的增加而减小。在单一气体吸氢实验中,氢原子浓度减小的趋势较氘原子缓慢;而在氢氘混合气体吸氢实验中,当容器中的氢氘压强比p(H2)∶p(D2)≥05∶1时,固体中氘氢浓度之比随钼浓度的增加而降低,但当p(H2)∶p(D2)<05∶1时,氘氢浓度之比随钼浓度的增加而升高。因此,由于Ti Mo界面的互扩散,吸氢出现了显著的氢同位素效应,钼的存在不利于体系对氢同位素气体的吸收。     

Ti_(1.08)V_(1.21)Cr_(0.28)Fe_(0.40)Zr_(0.03)合金的贮氢性能研究与物相分析

研究了Ti_(1.08)V_(1.21)Cr_(0.28)Fe_(0.40)Zr_(0.30)合金的吸氢特性以及与实际应用有关的一些问题。利用XRD和SEM技术对合金及其氢化物的物相进行了分析。结果表明:合金容易活化;吸氢量大。在室温时,吸氢压力-组成等温线坪台压力接近101325Pa,坪台区范围约0.8H/M～1.6H/M(该试验最高压力范围内)。合金氢化物(吸氢量约1.25H/M时)的形成焓变为-27.4kJ/moleH_2;熵变为-200J/(K·moleH_2)。合金吸氢速度和氢化物离解速度快;600℃时氢化物离解回收率高于95％。氢气中杂质氦对合金吸氢量无明显影响,而使吸氢速度明显降低;空气对合金的吸氢速度和吸氢量都有较大影响。合金有较好的抗粉化性能,吸氢量为1.1H/M时合金体胀率约11％。合金氢化物在空气中不自燃。合金吸氢后分解为多相。     

Ti87.5Hf12.5合金的贮氢性能

测定了Ti87.5Hf12.5合金的吸氢体膨胀率和氢化物热稳定性,并与Ti及TiZr、TiV和TiNb等a相合金的相应特性进行了对比.TiHf合金具有最小的吸氢体膨胀率和最高的氢化物共析转变温度.Hf的添加显著长大了TiH2的晶格常数.测试了TiHf合金的吸放氢动力学特性和吸氢PCT曲线,Hf的添加未显著改变Ti的吸氢热力学特性,外推室温吸氢平衡压与Ti的相当.     

纯Ti吸放氢过程研究

对纯Ti在500和580℃下的吸氢速率常数进行了测定。500℃时,纯Ti吸氢速率随循环测试次数增多而变小,且吸氢动力学曲线出现拐点,吸氢时发生α→β和β→δ2次相变。580℃下的吸氢速率较500℃下的明显变快,吸氢动力学曲线为直线,吸氢时未发生β→δ相变。研究了表面及晶粒度对磁控溅射和球磨制备的TiH2放氢过程的影响。结果表明,在相同升温速率下,由磁控溅射和球磨制备的纳米晶氢化物的放氢曲线与块体材料的放氢曲线存在显著差异。此现象与样品中的缺陷结构有关。     

LaNi_(4.9)Al_(0.1)热力学性能的氚老化效应

测定了LaNi4 .9Al0 .1热力学性能的氚老化效应。结果表明 ,吸氚 112 0d后 ,LaNi4 .9Al0 .1氚化物的解吸等温线表现出坪台压力和可逆吸氢容量随时间的增加而降低 ,并形成残留氚 (tritiumheel) ;坪斜和热力学焓变ΔH和熵变ΔS随时间的增加而增加     

LaNiAl材料储氚老化氚踵特性

采用研制的全金属吸放氚系统,恒温等容条件下,针对LaNiAl系列储氚材料,测定了储氚老化300、1 000、1 200d左右吸放氚等温解吸曲线(PCT特性曲线)、氚踵特性,并开展了氚踵的氢排代回收工艺研究。测试结果表明:随着老化时间的延长,LaNiAl材料均表现出明显的氚老化特性:吸放氚PCT特效曲线改变,坪台压降低,坪斜增大,可逆吸放氚容量减少,氚踵逐渐形成并升高。建立了氚踵数学模型,并与美国氚老化测试结果进行了对比。氢氚排代置换实验研究结果表明:经过10次氢排代置换氚,材料中残余氚量从氚金属原子比(T/M)=0.128 27降低到0.000 02,几乎可全部回收合金中氚。     

储氢薄膜的吸氢动力学研究

研究了储氢薄膜材料在两相区范围内的吸氢动力学,它包括４个力学过程：氢在气／固表面的化学吸附,氢原子的表面渗透,氢原子在氢化物层的扩散和金属／氢化物界面上的氢化物生成。     

铀表面钛镀层原位氧化行为的AES和EELS研究

利用铀的电子能量损失谱(EELS)、俄歇电子能谱(AES)原位．研究了在室温下O2气氛中表面Ti膜初始氧化过程中表面结构的变化。结果表明，Ti膜的氧化速度比金属Ti更快；Ti膜氧化时与金属Ti一样可形成Ti(固溶O)、TiO、Ti2O3、TiO2．氧化物以岛状形式生长，并以多种氧化态并存；其氧化过程为Ti→Ti(固溶O)→TiO→Ti2O3→TiO2。     

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.