Y/Ce注入对Zr-4合金高温氧化行为的影响

为了比较研究Y、Ce离子注入对Zr-4合金氧化性能的影响，探索离子注入后的改性机制，对Zr-4合金表面分别注入了不同剂量的两种离子并在500℃条件下进行空气氧化．氧化曲线表明：Y、Ce离子注入均能明显改善Zr-4合金的氧化性能，改善的程度随注入剂量的提高而增大；Ce离子注入后的改性效果略强于Y．使用XPS、GAXRD研究了注入样品高温氧化实验后的表层氧化膜成份及其相结构，探讨了Y、Ce离子注入提高Zr-4合金高温抗氧化性能的机理。     

ZIRLO合金和Zr-4合金在LiOH水溶液中耐腐蚀性能的研究

比较了ZIRLO合金和Zr-4合金两种样品在350℃、16．8MPa、0．04MLiOH水溶液中的耐腐蚀性能，发现Zr4合金样品在腐蚀转折之前的腐蚀增重比ZIRLO合金稍低，这时两种样品的氧化膜相对完整而致密。用二次离子质谱仪(SIMS)测量Li^ 在两种合金样品氧化膜剖面中的分布，发现Li^ 进入Zr-4合金氧化膜的深度比ZIRLO合金浅，但浓度比较高。而腐蚀至68天在Zr—4合金样品腐蚀发生转折后，其腐蚀增重远高于ZIRLO合金，这是因为此时Zr-4合金样品氧化膜因疏松而失去保护作用，而ZIRLO合金样品腐蚀至82天氧化膜仍致密而完整。ZIRLO合金中细小的βNb和Zr—Fe—Nb第二相粒子可能对保持氧化膜的完整性有重要作用。     

GH903合金的离子注入表面改性研究

用离子注入、氧化和慢正电子束分析研究了ＧＨ９０３合金的氧化性能的改善与微观作用机理。注入的Ｃｒ＋．Ｙ＋的能量均为６０ｋｅＶ，注入的剂量分别由１ｘ１０１７．ｃｍ－２（Ｃｒ＋）、１ｘ１０１５Ｃｍ－２（Ｙ＋）和［１ｘ１０１５．ｃｍ－２（Ｙ＋）＋１ｘ１０１７·ｃｍ－２（Ｃｒ＋）］。结束显示，注入样品与未样品相比。氧化增重分别减少４．８％（注Ｃｒ＋）、２４．２％（注Ｙ＋）和３２．３％（注Ｙ＋＋Ｃｒ＋）。这表明合金氧化性能改善的作用机理主要是注入离子对样品浅表层内缺陷的填充与退火。同时，注入元素的化学性能和使样品表面更致密也起了重要作用。     

钼离子注入对锆-4合金耐腐蚀性的影响

观察钼离子注入对锆-4合金在硫酸水溶液中耐腐蚀性的影响。使用MEVVA(Metalvaporvacuumarc)源对锆-4合金表面注入1×1016—1×1017cm-2剂量的钼离子,用X射线光电子能谱(XPS)分析其表面元素价态;用三次极化扫描评价其在1mol·L–1硫酸水溶液中的耐腐蚀性;并对三次极化后的样品进行扫描电镜(SEM)观察。实验表明,当钼离子注入剂量小于5×1016cm-2时,注入样品的耐腐蚀性显著增强。当钼离子注入剂量为1×1017cm-2时,注入样品的耐腐蚀性反而比未注入时差。讨论了钼离子注入锆-4合金后耐腐蚀性改变的原因。     

离子注入Cr、Y、Nb对γ-TiAl金属间化合物高温氧化性能的影响

采用MEVVA离子源将Cr、Y、Nb离子分别注入γ -TiAl金属间化合物 ,注入能量 50—6 0keV ,注入剂量为 1× 10 17cm- 2 ,研究γ -TiAl在 10 0 0℃空气中的循环氧化行为。结果表明 ,Cr离子和Y离子注入对γ -TiAl的高温氧化性能均没有明显影响 ;Nb离子注入γ -TiAl,在氧化初期 ,抗氧化性能得到显著提高 ,但随着氧化过程的继续 (超过 10 0h) ,这种改善作用逐渐降低。实验发现 ,通过离子注入和基体合金化向γ -TiAl中加入相同元素 ,由于工艺过程的差异 ,对其高温氧化性能的影响不同。在长时间高温氧化 (10 0 0℃ )条件下 ,离子注入表面改性无法达到提高γ -TiAl抗氧化性能的目的     

离子束辅助沉积铌提高铀的抗腐蚀性能研究

利用离子注入技术在铀表面进行了离子束辅助沉积铌和离子注入铌形成表面改性层，并对改性层的厚度、注入元素的分布进行俄歇电子能谱（AES）分析和表面相及结构的X射线衍射谱（XRD）分析，用电化学极化法测试抗腐蚀性能。结果表明：离子束辅助沉积表面改性层比离子注入表面改性层明显增厚，铀的耐蚀性得到进一步改善。最后讨论了注铌改性层耐蚀性提高的原因。     

真空电子束焊接对锆合金耐腐蚀性能的影响

用真空电子束焊接方法将Zr-4板对接焊后，焊缝的耐腐蚀性能很差，在400℃过热水蒸汽中腐蚀3—14天后，焊接熔化区的表面形成了白色的氧化膜。用电子探针研究了熔区中合金成分的变化和耐腐蚀性能间的关系，锆果表明：熔区中Sn、Fe和Cr合金元素的挥发损耗是造成耐腐蚀性能变差的主要原因，当采用合金成分高于Zr-4的锆合金板与Zr-4板对接焊后，可以补偿熔区中合金元素因挥发而造成的损耗，明显改善焊缝熔区的耐腐蚀性能；若在锆合金中添加0．4％—0．5％的Nb，使熔区中形成新的锆合金，特有益于改善焊缝的耐腐蚀性能．但焊接后的样品应在500—600℃进行退火处理，使添加Nb后形成的βZr分解为稳定的αZr βNb，以进一步改善焊缝的耐腐蚀性能。     

镧离子注入对纯锆耐蚀性的影响

为了研究镧离子注入对纯锆耐蚀性的影响,样品表面分别注入了1×10~(16)-1×10~(17)cm-2的镧离子,使用MEVVA源作为注入源,注入能量为40 kv。X光电子谱(XPS)分析了注入样品表面镧的价态,三电极动电位扫描测定了注入样品在0.5 mol/L H2SO4溶液中的极化曲线,通过与空白样(未注入样品)比较可知,镧离子注入后,纯锆样品的耐蚀性大大提高。最后,讨论了耐蚀性提高的机理。     

离子注入改善钢表面性能的研究

离子注入提供一种精确控制和改善钢表面性能的最灵便和最直接的方法。本文研究了离子注入对钢的表面硬度、光反射率和高温氧化性能的影响。     

N+离子注入对锆-4合金耐腐蚀性能的影响

为了研究N+离子注入对锆-4合金耐腐蚀性能的影响,本文使用直线加速器产生的N+离子注入锆-4合金样品,通过对离子注入后样品电化学曲线的测量,分析不同剂量下N+离子注入对锆-4合金钝化电流密度的影响,同时使用透射电子显微镜分析注入层的微观结构.结果表明,随着注入剂量的提高(0-1×1016cm-2),样品钝化电流密度下降,耐腐蚀性能提高,其原因主要归结于样品表层由多晶结构到非晶结构的转变过程.     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

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.     

Information for authors

<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen-     

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

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