惰性气体离子辅助产生Ca+、He+及其注入钛箔和纳米钛膜的微结构分析

介绍了由弗里曼离子源在惰性气体辅助下产生Ca+、He+的研究及其分别注入钛箔和纳米钛膜的微结构分析.Ca+ 注入Ti箔样品的XPX分析表明在1×1018/cm2注入剂量下,Ca的含量达到33﹪,注入Ca在钛表面主要形成CaTiO3、CaO和TiO2的化学结合的方式与钛基体连接;He+注入纳米钛样品的XRD的衍射谱在15-40°范围内明显分裂及变得较为尖锐,由谢乐公式计算出的纳米膜样品在(100)(101)晶面晶粒粒度大小分别为20.2nm和19.3nm,表明纳米钛膜注氦后仍保持纳米尺度.而AFM在微米视场下观察到纳米钛膜的表层粒子粒度虽有所长大,但在纳米视场却观察到大量的亚结构,结合AFM观察和XRD的分析结果证明在高剂量注入下,存在纳米钛膜表层粒子同时又被碎化成微晶使注氦纳米钛晶粒仍保持纳米尺度的重要现象.     

磁控溅射沉积含He纳米晶钛膜制备

采用直流磁控溅射方法，通过分别改变衬底温度及He分压来制备不同氦含量的钛膜。利用PBS、XRD、TEM及AFM分别对钛膜中的He含量、平均晶粒尺寸及膜的表面形貌进行分析。结果表明：在不同温度范围内，温度变化对所制备钛膜中He含量的影响明显不同；He含量与晶粒尺寸直接相关，氦原子进入钛膜后，抑制了晶粒的长大；随着钛膜中He与Ti的原子个数比由1.0%增加到11.9%，TEM测得的平均晶粒尺寸由约35nm减小到约4nm；选择合适的He分压，能够制备出He含量较高的氦钛膜。     

纳米晶粒钛膜中氦注入的剂量保持和释放规律

在室温～400℃范围内,用卢瑟福质子背散射技术测量了100keV、注入剂量2 2×1018cm-2的纳米晶粒钛膜中氦的浓度分布、不同温度下的剂量保持及其浓度释放。室温下经210d后,氦在该纳米晶粒钛膜中的剂量保持达68%,其He Ti原子比为52 6%;100℃下氦的保持剂量为室温下的89 6%,此时的He Ti原子比为44%;400℃下的保持剂量为室温下的32 6%,He Ti原子比为17 1%。同时观察到了氦的释放随温度上升呈现波浪式的变化特点。从能量稳定性观点初步探讨了纳米晶粒钛膜有效保持氦的可能机制。     

常温氦离子注入纳米钛膜的微结构分析

在常温下,用200、100 keV He离子按He-Ti原子浓度比0.1、0.3和0.2的剂量注入纳米钛膜,采用现代表面分析技术对试样进行形貌观察与微观分析.测试分析结果表明注入前,沉积膜的原子力显微镜(AFM)形貌像呈现从几十至200 nm以上极不均匀的晶粒尺度;注入后,3个试样的晶粒均有所长大,且随着注入剂量的增加,其长大趋势更为明显.这些长大的晶粒中同时存在大量的亚结构,表明在高剂量氦离子注入下,导致出现表层晶粒细化现象;He离子注入后的试样在衍射角15°～40°之间出现可辨的衍射峰,其膜层内的平均晶粒尺寸约136 nm,说明经离子注入后,膜层内纳米粒子的结晶度得到进一步提高,晶粒度比注入前长大.此结果证实了AFM B微米级视场的观察.     

磁控溅射法制备含氦钛膜及膜中氦的热解吸研究

采用He/Ar复合气氛下磁控溅射方法,在Ti、TiZrYAl 和TiMoYAl等3种薄膜中引入浓度(氦-金属比)高达0.19的氦.引入的氦在膜层内沿深度均匀分布,并主要存在于直径为2～5 nm的高压He泡内.热解吸实验表明,在相同He含量下,TiHe膜中He的解吸峰温度与氚化钛中衰变产生的3He的解吸峰温度基本一致.与纯钛相比,合金膜中氦的热解吸谱宽化明显,表明He在合金膜内的捕获形式更为复杂.     

氚化钛膜中氦的热解吸行为初步研究

对He、Ti原子比n(He)/n(Ti)为0.004～0.300的7块氚化钛膜样品在1300K以下进行热解吸分析,以获得它们的热解吸谱。在低于1300K范围内,氚化钛膜共有4种氦的热释放峰,分别对应于贯穿至表面的氦泡、近表面的氦、体相中的氦泡和氦的小团簇。对这4种类型的氦释放峰的解吸温度和解吸量随膜中总氦量的变化分别进行分析,研究观测膜中各种状态存在的氦量随n(He)/n(Ti)增加的变化趋势。实验观测到,升温将导致氚化钛膜可容纳的氦量大幅降低。     

惰性气体离子辅助产生Ca~+、He~+离子及其注入钛膜和纳米钛膜的微结构分析

介绍由弗里曼离子源在惰性气体辅助下产生Ca+、He+离子的研究及其分别注入钛膜与纳米膜的微结构分析。Ca+注入Ti膜样品的XPX分析表明 :在 1× 10 18注入剂量下 ,Ca的含量达 33% ,注入Ca在钛表面主要形成CaTiO3、CaO和TiO2 的化学结合的方式与钛基体连接 ;He+注入纳米钛样品的XRD的衍射谱在 15°—4 0°范围内明显分裂及变得较为尖锐 ,由谢乐公式计算出XTA0 5 - 4的纳米膜的平均晶粒粒度已增大为190nm ,证明纳米膜内层晶粒度确有一定长大。而AFM在微米视场下观察到纳米钛膜的表层粒子粒度虽有所长大 ,但在纳米视场却观察到大量的亚结构 ,表明在高剂量注入下 ,存在纳米钛膜表层粒子同时又被碎化成微晶的重要现象。     

纳米微晶钛膜结构及其热稳定性

介绍了用离子束辅助沉积法制备纳米微晶钛的活性特点.纳米钛膜在较宽范围温度处理后,用X射线衍射线宽法(谢氏公式)测定出Ti及TiHx晶粒尺寸长大有限.β-Ti纳米微晶氢化后转变成TiHx的现象由X射线衍射(XRD)谱图证实.由氢饱和工艺提供的氢钛原子比印证了TiHx XRD谱线代表的原子比.     

直流磁控溅射法制备含氦铝膜

采用氦氩混合气氛下直流磁控溅射沉积方法制备含有氦原子的金属铝膜。经碳原子弹性前冲散射分析（C-ERDA），薄膜中氦原子浓度可达约7％，且分布均匀。实验研究了薄膜中的氦含量与溅射真空室气氛中氦的相对含量、基底偏压及沉积温度间的关系。薄膜的X射线衍射分析结果显示：膜中的氦含量变化并未引起明显的峰位移，只是随氦含量增加谱峰宽化。热释放实验证实，氦在薄膜中稳定存在，约500℃以上时方出现氦的释放。     

高温He离子辐照GH3535合金的损伤效应

采用500 keV的He离子在750℃下对GH3535合金样品进行辐照,然后利用掠入射X射线衍射(GIXRD)、透射电子显微镜(TEM)和纳米压痕仪分别对样品的氦泡和位错环辐照缺陷的演化及纳米硬度的变化进行了研究。结果表明,GH3535合金晶格辐照后发生了轻微畸变;离子辐照在样品中形成了大量尺寸为2～5 nm的氦泡和位错环。辐照产生的氦泡和位错环等缺陷在基体中钉扎位错,从而使材料产生了辐照硬化现象,样品硬度随辐照剂量的增加而增大。当辐照剂量达2×10~(16) cm~(-2)时,辐照样品发生了明显的硬化饱和现象,利用Nix-Gao模型计算得此时的硬化程度为64%。     

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.