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EXAFS study on arsenic species and transformation in arsenic hyperaccumulator

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Science china(Life sciences) 2004年第2期47卷 124-129页

作者： HUANG Zechun1, CHEN Tongbin1, LEI Mei1, HU Tiandou2 & HUANG Qifei1 1. laboratory of Environmental Remediation, institute of Geographical sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, china 2. laboratory of synchrotron radiation, institute of high energy physics, chinese academy of sciences, beijing 100039, china Correspondence should be addressed to Chen Tongbin 1. laboratory of Environmental Remediation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. Plaboratory of synchrotron radiation Institute of High Energy Physics Chinese Academy of Sciences 100039 Beijing China

synchrotron radiation extended X-ray absorption fine structure (SR EXAFS) was employed to study the transformation of coordination environment and the redox speciation of arsenic in a newly discovered arsenic hyperaccumulator, Cretan brake (Pteris cretica L. var ner-vosa Thunb). It showed that the arsenic in the plant mainly coordinated with oxygen, except that some arsenic coordinated with S as As-GSH in root. The complexation of arsenic with GSH might not be the predominant detoxification mechanism in Cretan brake. Although some arsenic in root presented as As(V) in Na2HAsO4 treatments, most of arsenic in plant presented as As(III)-O in both treatments, indicating that As(V) tended to be reduced to As(III) after it was taken up into the root, and arsenic was kept as As(III) when it was transported to the above-ground tissues. The reduction of As(V) primarily proceeded in the root.

关键词： hyperaccumulator, Cretan brake (Pteris cretica L. var nervosa Thunb), arsenic, species, EXAFS.

用原位x射线小角散射研究块体非晶合金Zr_(55)Cu_(30)Al_(10)Ni_5的结构弛豫

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物理学报 2003年第9期52卷 2219-2222页

作者：柳义柳林王俊赵辉荣利霞董宝中中国原子能科学研究院北京102413 华中科技大学材料学院武汉430074 中国科学院高能物理研究所同步辐射实验室北京100039

应用同步辐射x射线小角散射法在原位对块体非晶合金Zr55Cu30 Al1 0 Ni5在等温退火过程中的微结构变化进行研究 .实验表明 :在等温退火过程中电子密度涨落反映了晶化之前的结构弛豫过程 ;在一定的退火温度下、随退火时间的增加 ,拓扑短... 详细信息

应用同步辐射x射线小角散射法在原位对块体非晶合金Zr55Cu30 Al1 0 Ni5在等温退火过程中的微结构变化进行研究 .实验表明 :在等温退火过程中电子密度涨落反映了晶化之前的结构弛豫过程 ;在一定的退火温度下、随退火时间的增加 ,拓扑短程序弛豫与化学短程序弛豫之间存在一个电子密度均匀化的过程 ;导致这两种弛豫过程转变的退火时间与退火温度有关 ,温度越高。

关键词：原位x射线小角散射块体非晶合金等温退火结构弛豫 Zr55Cu30Al10Ni5合金电子密度涨落

小角x射线散射法研究甲基改性氧化硅凝胶的双分形结构

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物理学报 2003年第2期52卷 442-447页

作者：徐耀李志宏范文浩吴东孙予罕王俊董宝中中国科学院山西煤炭化学研究所煤转化国家重点实验室太原030001 中国科学院高能物理研究所同步辐射国家实验室北京100039

以正硅酸乙酯 [Si(OC2 H5) 4,TEOS]和甲基三乙氧基硅烷 [CH3Si(OC2 H5) 3,MTES]为前驱体 ,通过共水解法和两步法制备出两种不同的甲基改性氧化硅凝胶 ,在北京同步辐射光源 (BSRF)小角x射线散射 (SAXS)站测量了凝胶的散射强度 ,计算了凝... 详细信息

以正硅酸乙酯 [Si(OC2 H5) 4,TEOS]和甲基三乙氧基硅烷 [CH3Si(OC2 H5) 3,MTES]为前驱体 ,通过共水解法和两步法制备出两种不同的甲基改性氧化硅凝胶 ,在北京同步辐射光源 (BSRF)小角x射线散射 (SAXS)站测量了凝胶的散射强度 ,计算了凝胶的平均粒径、两相间比表面积等参数 ,在此基础上分析了凝胶的分形特征 ,发现存在两个尺度上的分形结构 ,分别对应于从SiO2 原生颗粒到一次团聚体和从一次团聚体到簇团两种尺度 .辅以透射电子显微镜 (TEM)观测 ,证实由两种方法获得的凝胶具有非常不同的微观结构 .实验证明 ,利用SAXS技术研究甲基改性凝胶的分形特征是获得凝胶微观结构的有力工具 .

关键词：甲基改性凝胶氧化硅小角x射线散射 SAXS 双分形结构散射强度

Fractionations of rare earth elements in plants and their conceptive model

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Science china(Life sciences) 2007年第1期50卷 47-55页

作者： DING ShiMing1,2, LIANG Tao2, YAN JunCai3, ZHANG ZiLi3, HUANG ZeChun2 & XIE YaNing4 1 Nanjing institute of Geography & Limnology, chinese academy of sciences, Nanjing 210008, china 2 institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, china 3 Anhui Agricultural University, Hefei 230036, china 4 State Key laboratory of synchrotron radiation, institute of high energy physics, chinese academy of sciences, beijing 100039, china 1. Nanjing institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China 2. institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China 3. Anhui Agricultural University Hefei 230036 China 4. State Key laboratory of synchrotron radiation Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China

Fractionations of rare earth elements (REEs) and their mechanisms in soybean were studied through application of exogenous mixed REEs under hydroponic conditions. Significant enrichment of middle REEs (MREEs) and heavy REEs (HREEs) was observed in plant roots and leaves respectively, with slight fractionation between light REEs (LREEs) and HREEs in stems. Moreover, the tetrad effect was observed in these organs. Investigations into REE speciation in roots and in the xylem sap using X-ray absorption spectroscopy (XAS) and nanometer-sized TiO2 adsorption techniques, associated with other controlled experiments, demonstrated that REE fractionations should be dominated by fixation mechanism in roots caused by cell wall absorption and phosphate precipitation, and by the combined effects of fixation mechanism and transport mechanism in aboveground parts caused by solution complexation by intrinsic organic ligands. A conceptive model was established for REE fractionations in plants based on the above studies.

关键词： rare earth elements (REEs) fractionation tetrad effect plant accumulation X-ray absorption spectroscopy (XAS) nanometer-sized TiO2

La_2CaB_(10)O_(19)∶Eu^(3+)的VUV-VIS范围光谱的研究

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中国稀土学报 2002年第6期20卷 556-559页

作者：赫泓梁宏斌于英宁王淑彬苏锵陶冶巨新侯雪颍中国科学院长春应用化学研究所稀土化学与物理重点实验室吉林长春130022 中山大学光电材料和技术国家重点实验室化学与化工学院广东广州510275 中国科学院高能物理研究所北京同步辐射实验室北京100039

研究了La2CaB10O19∶Eu3+红色发光材料的高分辨发射光谱和UV VUV激发光谱。根据发射光谱和荧光寿命,认为进入晶格的Eu3+占据了两种格位,一种Eu3+占据了与O2-离子十配位的La3+的格位,另一种Eu3+则占据了与O2-离子八配位的Ca2+的格位。又... 详细信息

研究了La2CaB10O19∶Eu3+红色发光材料的高分辨发射光谱和UV VUV激发光谱。根据发射光谱和荧光寿命,认为进入晶格的Eu3+占据了两种格位,一种Eu3+占据了与O2-离子十配位的La3+的格位,另一种Eu3+则占据了与O2-离子八配位的Ca2+的格位。又从激发光谱的分析中,得到Eu3+的电荷迁移带(CTB)是峰值位于244nm的宽带,而位于130～170nm之间的成份复杂的宽带包括硼酸盐基质的吸收带和Eu3+的f d跃迁的结论。

关键词： La2CaB10O19:Eu^3+ 稀土真空紫外光谱高分辨光谱硼酸盐铕离子荧光粉

Studies on BEPC upgrade from pretzel to double-ring

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 2084-2089页

作者： ZHANG Chuang institute of high energy physics,chinese academy of sciences,beijing 100049,china 1. institute of high energy physics Chinese Academy of Sciences Beijing 100049 China

physics opportunity in the charm and τ energy region calls for higher luminosity of the beijing Electron-Positron Collider (BEPC).The BEPC has experienced continuous improvement since its completion in ***,as a major upgrading project of the BEPC,aims at enhancing its luminosity of factor 30–100,following the principle of "one machine,two purposes" as adopted in BEPC,so that both high energy physics and synchrotron radiation experiments can be carried out with *** the BEPC to BEPCII,the double-ring scheme with multi-bunch e +-e-collision in the large crossing angle was studied in comparison with the single-ring pretzel *** the dedicated synchrotron radiation operation,artful "bridges" are designed to connect two halves of the outer ring in both the southern and the northern crossing *** paper reviews the studies on the BEPC upgrade from pretzel to double-ring structure of BEPCII.

关键词： collider storage ring high energy physics synchrotron radiation

Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) bulk metallic glass up to 24 GPa

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Science china(physics,Mechanics & Astronomy) 2005年第3期48卷 319-324页

作者： LI Gong 1, 2 , ZHAN Zaiji 2 , LIU Jing 3 , YUN Jinku 1 , SUN Liling 2 , LIU Riping 1 , ZHANG Jun 2 & WANG Wenkui 1, 2 1. Key laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. Center for Condensed Matter physics, institute of physics, chinese academy of sciences, beijing 100080, china 3. BSRF, institute of high energy physics, chinese academy of sciences, beijing 100039, china 1. Key laboratory of Metastable Materials Science and Technology Yanshan University 066004 Qinhuangdao China 2. Center for Condensed Matter physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 3. BSRF Institute of High Energy Physics Chinese Academy of Sciences 100039 Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

INVESTIGATION ON THE VALENCE STATE OF Ce ATOMIN BULK AND NANOCRYSTAL CeO_2 BY X-RAY ABSORPTION ANDPHOTOEMISSION

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 511-516页

作者： K. Ibrahim, Z.Y. Wu, J. Zhang, M.I. Abbas, F.Q. Liu and H.J. Qian (beijing synchrotron radiation laboratory, institute of high energy physics, The chinese academy of sciences, P.O. Box 918, beijing 100039, china) beijing synchrotron Radiat. Lab. Inst. of High Energy Phys. Chinese Acad. of Sci. P.O. Box 918 Beijing 100039 China

Valence band photoemission spectra (PES) for both bulk and nanocrystal CeO2 have been measured on and off resonance of Ce 4d-4f absorption edge. The PES show that the bulk and nanocrystal CeO2 of diameter ranging from 8nm to 50nm exhibit a peak near Fermi edge with binding energy of about 1.8eV. The 1.8eV peak shows a strong dependence on excitation energy, although it looks like the contribution of Ce3+ ion following the data reported in literatures. However, according to the results of resonance photoemission and X-ray absorption spectra at 1s edge, this electronic structure may be associated to the intermediate state charge transfer effects.

关键词： rare earth oxide photoemission electronic structure photoabsorption

RESONANT PHOTOEMISSION OF BULK CeO_(2) AND NANO-CeO_(2) FILMS

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 539-543页

作者： M.I. Abbas, K. Ibrahim, Z.Y. Wu, J. Zhang, F.Q. Liu and H.J. Qian (beijing synchrotron radiation laboratory, institute of high energy physics, The chinese academy of sciences, P.O. Box 918, beijing 100039, china) beijing synchrotron Radiat. Lab. Inst. of High Energy Phys. Chinese Acad. of Sci. P.O. Box 918 Beijing 100039 China

Photoemission behaviors of nano-CeO2 films with particle sizes ranging from 8 nm to 50 nm and bulk CeO2 in Ce 4 d-4 f absorption region have been investigated. Resonant enhancements of Ce 4 f valance band and Ce 5 p bands for nano film and bulk material have been observed. The variation of electron density of states in valance bands of nano and bulk structures of CeO2 is discussed in terms of Ce 4 d-4 f resonance.

关键词： Nanostructured materials Optical films Oxides Photoemission Resonance