最新刊期
      卷 0 ， 期 0 ， 2020
      • HUANG Sheng LIU Peng DONG Yuhui YAO Deqiang GAO Zengqiang XIAN Dingchang
        Issue 9, (2004)
        摘要：The multi-wavelength anomalous dispersion (MAD) experiment is one of the main methods in three- dimensional structure determination of macromolecular crystal. In the macromolecular crystallography station (3W1A) of Beijing Synchrotron Radiation Facility (BSRF) the first MAD experiment was completed in Oct. 2003 and good results were obtained. This paper discusses the details of the MAD experiment and data processing. The success of the experiment has shown that the 3W1A station in BSRF has the ability to supply this most important and popular structure determination method.  
        关键词：Synchrotron radiation;Macromolecule;Multi-wavelength anomalous dispersion   
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        发布时间：2021-03-12
      • ZHAO Tao WANG Xiangqi SHANG Lei WANG Lin ZHANG Haiyan
        Issue 9, (2004)
        摘要：Based on the small-signal model of a phase-shifted full bridge DC/DC converter, analysis is made on the performance of a voltage regulating power supply in frequency domain. Experimental results are presented from a prototype.  
        关键词：Small-signal model;Phase-shifted full bridge converter;DC voltage-steady supply;Performance;Design   
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        发布时间：2021-03-12
      • XU Pengshou DENG Rui PAN Haibin XU Faqiang LI Yonghua
        Issue 9, (2004)
        摘要：The surface structure of GaAs(001) has been studied by using angle resolved photoemission fine structure (ARPEFS), which confirms the ‘Ga bi-layer’ model proposed by Biegelsen. The results show that two adjacent outmost Ga atoms (dimmer) move close together along [110] direction to form an 8.3% deviation from the bulk site. And the outmost Ga dimmers relax inward 2.1%. The surface structure of S-passivated GaAs(001) has also been investigated with the method of X-ray photoelectron diffraction (XPD). The results demonstrate that the passivated S atoms are located on the bridge of the first layer Ga atoms and bind them with the bond length of 3.62? and the bond angle of 61.2°. The surface polarity of GaN(0001) grown on the substrate of Al2O3 is also studied by using energy dependence photoelectron diffraction as well as the calculation of multiple scattering cluster models, which confirms that its polarity is Ga termination.  
        关键词：Photoelectron diffraction;Semiconductor;Surface structure;GaAs;GaN   
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        发布时间：2021-03-12
      • ZHANG Yuanxun WANG Yinsong LI Delu LI Aiguo ZHANG Guilin
        Issue 9, (2004)
        摘要：In order to explore the function and interaction between the ZnT3 mRNA expression and elemental zinc distribution in mouse brain slice, zinc concentration and its distribution were determined by SRXRF and ZnT3 mRNA expression in organs was examined by RT-PCR method. The analysis results show that the zinc content is not evenly distributed. The zinc content in cerebral cortex and hippocampus is nearly 5—10 times higher than that in other positions. Correspondingly, ZnT3 mRNA in cerebral cortex, hippocampus and testis has higher abundance, but it can not be examined out in other organs. Furthermore, the results suggest that ZnT3 facilitates the accumulation of zinc in synaptic vesicles and may play important roles in the structuring of vesicular zinc pool.  
        关键词：SRXRF;Brain;Zinc element;Zinc transporter;Gene expression   
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        发布时间：2021-03-12
      • ZOU Jianxin WU Aimin QIN Ying HAO Shengzhi SONG Lili WANG Xiaogang DONG Chuang
        Issue 9, (2004)
        摘要：A numerical model based on the simulation of temperature and stress field is established to describe a diffusion process on High Current Pulsed Electron Beams (HCPEB) treatment. The calculation method and results are shown in this paper. The model and the method can also be used to solve other diffusion processes under thermal impactions. It is shown that concentration flow still plays a major role in the diffusion process; diffusion decreases after several times of pulses; diffusion effects are relatively significant if impurities lie on the surface. This is the theoretical basis of the duplex treatment of surface alloying by HCPEB. Comparing with some experimental results and related calculations, we can find that the diffusion activation energy will significantly decrease during HCPEB treatment due to a high concentration of vacancies induced by bombardment; the convective mixing process will play a major role in diffusion treatment if the surface is in melt.  
        关键词：High Current Pulsed Electron Beams (HCPEB);Diffusion;Computer simulation   
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        发布时间：2021-03-12
      • GUO Wenlu ZHANG Xiurong
        Issue 9, (2004)
        摘要：As a calculating instance of low-energy and zero-fluence isotope ( 63Cu-65Cu and92 Mo-100Mo) sputtering, the Monte Carlo (MC) simulation has been used to study whether the isotope enrichment is ejection-angle-dependent or not, and also to study which contribution, from the primary knock-on atoms or from the secondary ones, is essential. Various views are summarized and our view is presented.  
        关键词：Isotopic enrichment;Sputtering;Momentum asymmetry   
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        发布时间：2021-03-12
      • PENG Dequan BAI Xinde CHEN Xiaowen ZHOU Qinggang LIU Xiaoyang YU Renhong
        Issue 9, (2004)
        摘要：In order to study the effect of molybdenum ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted by molybdenum ions with a fluence range of 1×1016—1×1017 cm-2. The valence of the surface layer was analyzed by X-ray photoelectron spectroscopy (XPS) and the three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion resistance of zirconium in 1 mol·L–1 H2SO4 solution. Scanning electron microscopy (SEM) was used to observe the surface morphology of the three-sweep potentiodynamic polarized samples. It was found that a significant improvement was achieved in the aqueous corrosion behavior of zircaloy-4 implanted with molybdenum ions when the fluence was smaller than 5× 1016 cm-2. When the fluence was higher than 1×1017 cm-2, the corrosion resistance of zircaloy-4 implanted with molybdenum ions decreased as compared with that of the as-received zircaloy-4. Finally, the mechanism of the corrosion resistance improvement of the molybdenum-implanted zirconium was discussed.  
        关键词：Zircaloy-4;Corrosion resistance;Molybdenum ion implantation;Potentiodynamic polarization;Polarization curves   
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        发布时间：2021-03-12
      • WANG Hongbo WANG Sen YU Guojun LI Yulan HE Suixia GONG Jinlong LU Rongrong ZHU Dezhang ZHU Zhiyuan
        Issue 9, (2004)
        摘要：A highly-ordered, hexagonally arranged alumina nanopore template was prepared by self-organized two-step anodization process of aluminium in oxalic acid solution. Highly parallel pores were obtained within domains of a few micrometers. Highly-ordered, parallel carbon nanotube arrays were successfully grown in the alumina template nanopores by chemical vapor deposition catalyzed by alumina itself. The nanotube arrays are suitable for channeling of particle beams. The structures of aluminium, alumina template and carbon nanotubes were characterized by scanning electron microscopy(SEM) and electron back scattered diffraction(EBSD). The growth mechanism and formation condition of both alumina template and carbon nanotube were discussed.  
        关键词：Anodization;Template;Array;Carbon nanotube   
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        发布时间：2021-03-12
      • LIU Zhanfeng1 YUE Haiyan2 YUAN Qipeng1 WANG Wenchuan1 1
        Issue 9, (2004)
        摘要：Compared with common amino acids, the isotope-labeled amino acids have accordant structure and analogical property. In the research of crude products, protein metabolism, morbid diagnosis and cure of organism, they provide a secure, effective, convenient tracing tool by the peculiarity of amino acid participation in protein synthesis and metabolism. The paper mainly reviews the advances in the applications of isotope-labeled amino acids in medicine, biology, pharmacology and chemistry.  
        关键词：Isotopes;Amino acids;Application   
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        发布时间：2021-03-12
      • JIANG Haiyan1,2 WU Yican1 ARTS Team1 1
        Issue 9, (2004)
        摘要：In this paper, the interaction between energetic particles and tumor cell in BNCT (Boron Neutron Capture Therapy) has been simulated by SRIM code based on Monte-Carlo simulation.The distribution and track of particles as well as the damage of the target have been presented when α-particle implantation to tumor cell perpendicularly from the cell membrane.The deposited energy of the energetic particles produced from the B(n, 10 α)7Li neutron capture reaction in different situations of the cell model is also calculated and the computed results are analyzed using cell survival curves.The conclusion may be important to understand the biological effect of single particle and the distribution of microdosimetry at cellular and subcellular level.In addition, it would provide elementary theory for microdosimetry of BNCT.  
        关键词：Boron Neutron Capture Therapy (BNCT);Monte Carlo simulation;Energy deposition;Cell survival   
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        发布时间：2021-03-12
      • XIA Jiaoyun WANG Yongxian YU Junfeng YIN Duanzhi
        Issue 9, (2004)
        摘要：The fac-[Μ(CO)3L3]+(Μ=188/186Re, Tcm, L=H2O) is a promising radiolabeling precursor due to its 99 favorable radiobiological characteristics. The progress of small biomolecules, proteins, and peptides labeled with the fac-[Μ(CO)3]+(Μ=99Tcm ,188/186Re)core is summarized, and its development in the future is also discussed.  
          
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        发布时间：2021-03-12
      • PENG Tao GU Chenglin
        Issue 9, (2004)
        摘要：Stress is the most serious obstacle in raising magnetic intensity of a high-pulsed magnet. However, it is difficult to determine accurately both in theoretical analysis and in electromechanical design as its complicated distribution and interaction. In this paper, a finite element method is applied to calculate the stress and all present coupled component, such as pre-stress, electromagnetic force and thermal stress etc., are all taken into account. Some helpful rules for magnet design are obtained in terms of numerical results.  
        关键词：Pulsed magnet;Stress;Finite element analysis   
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        发布时间：2021-03-12
      • ZHANG Yanli AN Qi LIU Shubin WANG Yanfang
        Issue 9, (2004)
        摘要：The measurement of time signals in flight time readout (TOF) electronics of the third modification project of Beijing Spectrometer (BESIII) is very difficult according to the very high-resolution request, so we need to strictly test the design of the circuit for time measurement. This paper introduces the design of a high accurate signal generator circuit for this testing, which can generate pulse signal with the jitter less than 23.623 ps and clock signal with the jitter less than 12.265 ps. And two pivotal technologies, i.e. the designs of high-speed, high-resolution clock circuits and pulse generator circuits are discussed in this paper too.  
        关键词：VME;High accurate signal generator;High accurate clock signal;Pulse signal CLC TN0   
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        发布时间：2021-03-12
      • JIAO Pengcheng1 WANG Mili2 LIU Chenglin2,3 1
        Issue 9, (2004)
        摘要：Lop Nur is a playa located in the east of Tarim basin, Xinjiang, China. A plenty of brine is reserved in the upper evaporates of the upper-middle Pleistocene strata in Luobei depression, Lop Nur. The brines have higher salinity and are rich in potassium, with average 1.40% tenor of KCl. And high percentage of tritium in the upper ground water is measured, with average content of 40.6 TU. Laterally the tritium content variation is: higher in periphery and lower in center; while vertically the tritium content becomes lower with the burial depth increasing. With the use of piston model and completely-mixing model, the age of the upper brine is calculated as 36—80 a. Therefore, brine contained large portion of nuclear-bombing tritium, which verified that since 1952, atmospheric water had precipitated and seeped into the playa of this area. The tritium-bearing modern precipitated water is imbibed into sediments through the aeration zone, in which karst is developed intensively, and tritium mixed with shallow brine uniformly. Owing to the slow evaporation of brine, fractional distillation happened, and “lighter water” with less tritium evaporated. So most of tritium has been rich in relic brine. The characteristics of lateral tritium distribution are believed to be the results of groundwater flow pattern in a salt lake basin.  
        关键词：Tritium;dating;Brine;Lop Nur salt lake   
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        发布时间：2021-03-12
      • LIU Ruiyan WANG Xu ZHANG Junshan WANG Xiumin GAO Lusi ZHU Meili
        Issue 9, (2004)
        摘要：The pack boronizing process has been used to treat pure nickel at a temperature of 950℃ for a boronizing time of 5 h. A dense and continuous boronized layer of 50 μm thick was obtained on pure nickel. This paper describes the corrosion of pure nickel and the boronized nickel in molten LiCl-10Li2O (the mass fraction of Li2O is 10%) at 750℃ under air by immersion experiments. The weight loss of the boronized coating was 8.4 mg·cm-2, about three times lower than that of unboronized pure nickel. The preferential corrosion of B in boronized layer effectively prevented the corrosion of nickel, thus improving the corrosion resistance of pure nickel in molten LiCl-Li2O.  
        关键词：Pure nickel;boronization;Molten LiCl-Li2O;Corrosion   
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        发布时间：2021-03-12
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