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Phase transition in layered perovskite-like manganate Ca3Mn2O7 under high pressure

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Science China Mathematics 2002年第7期45卷 900-905页

作者：朱嘉林李凤英刘景陈良辰禹日成靳常青 Lab. for Extreme Condition Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China Beijing High Pressure Res. Center Chinese Academy of Sciences Beijing 100080 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China

In situ high pressure energy dispersive x-ray diffraction.measurements on the layered perovskite-like manganate Ca3Mn2O7 powder under pressures were performed by using the diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca3Mn2O7 is unstable under pressure due to the easy compression of NaCI-type blocks. The structure of Ca3Mn2O7 underwent two phase transitions under pressures in the range of 0-35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

关键词： Ca3Mn2O7 synchrotron radiation x-ray diffraction.

A New Dimeric Phthalide from Angelica sinensis

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Chinese Chemical Letters 2006年第12期17卷 1579-1581页

作者： Ling YI Ping LI Zhi Ming BI Key Laboratory of Modem Chinese Medicines Ministry of Education and Department of Pharmacognosy China Pharmaceutical University Nanjing 210009

A new dimeric phthalide named Z, Z＇-3.3＇a, 7.7＇a-diligustilide was isolated from the roots of Angelica sinensis. Its structure was determined using spectroscopic methods and x-ray crystallographic diffraction.analy... 详细信息

关键词： Angelica sinensis dimeric phthalide x-ray diffraction.

The Preparation of B-type Starch Spherocrystals by Freezing Crystallization

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Chinese Chemical Letters 2004年第7期15卷 853-855页

作者： YanQiLIU JiuGaoYU xiuPingSUN CollegeofScience TianjinUniversityTianjin300072

The B-typed starch spherocrystals were prepared by the dissolution and freezing crystallization of acid-hydrolyzed starch obtained by the mild hydrolysis of maize starch. The spherocrystals were characterized with scanning electron microscope (SEM), x-ray diffraction. thermogravimetry (TG) and gel pervasion chromatogram (GPC). The results show that the preparation was a B-type spherocrystal with the average degree of polymerization of 14 glucose units, and the average diameter of crystal particles was about 7μm.

关键词： Starch spherocrystal freezing crystallization crystallinity acid-hydrolyzed maize starch x-ray diffraction.

The Crystalline Changes of Starch from Rhizoma Dioscorea by Acid Hydrolysis

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Chinese Chemical Letters 2006年第9期17卷 1255-1258页

作者： Shu Jun WANG Wen Yuan GAO Jing Lin YU Pei Gen xIAO College of Pharmaceuticals and Biotechnology Tianjin University Tianjin 300072 School of Science Tianjin University Tianjin 300072 Institute of Medicinal Plant Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100094

The changes in crystalline properties of starch from Rhizoma Dioscorea by acid hydrolysis was characterized by x-ray diffractometry （xRD）. The results revealed that the crystalline type of Rhizoma Dioscorea starch changed from C-type to A-type after 16 days of the acid hydrolysis. This phenomenon was different from that of other starches subjected to the acid hydrolysis. The results revealed that the B-polymorphs of C-type starch constituted the amorphous regions while the crystalline areas were mainly composed of A-polymorphs. The degree of crystallinity of the acid-thinned starch increased gradually with the time of acid hydrolysis.

关键词： Rhizoma Dioscorea starch crystalline acid hydrolysis x-ray diffraction.

Metamorphic Temperature Investigation of Coexisting Calcite and Dolomite Marble Examples from Nikani Ghar Marble and Nowshera Formation,Peshawar Basin,Pakistan

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Journal of Earth Science 2016年第6期27卷 989-997页

作者： Muhammad Fahad Yaseen Iqbal Mohammad Riaz Rick Ubic Simon A. T. Redfern Department of Electrical Engineering COMSATS Institute of Information Technology Abbottabad 22010 Pakistan Materials Research Laboratory Department of Physics University of Peshawar Peshawar 25120 Pakistan National Centre of Excellence in Geology University ofPeshawar Peshawar 25120 Pakistan College of Engineering Boise State University Boise 83401 USA Department of Earth Sciences University of Cambridge Cambridge 999020 United Kingdom

Using marble samples from the Nikani Ghar marble and Nowshera Formation from Northern Pakistan the determination of the temperature of metamorphism was undertaken with the help of calcite-dolomite solvus geothermometer. Two types of marbles, that is, calcite-dolomite marble and quartz-bearing calcite-dolomite marble were selected. Petrographic and scanning electron microscope analysis of dolomite samples indicated different grain sizes. x-ray diffraction.technique indicated the calcites MgCO3 content up to 7.93 mol.%. Nikani Ghar marble samples have shown lower contents of MgCO3 as compared to samples from Nowshera Formation. The calcite-dolomite-quartz marble has also showed relatively lower MgCO3 content and hence rather low temperature （-500 ℃）. The temperature reached during peak metamorphism of the investigated marble occurrence, based on calcitedolomite solvus was 628 ℃. Metamorphic temperatures derived from the present study were shown as a linear graph and values were in good agreement with the published literature.

关键词： calcite dolomite metamorphic temperature geothermometer x-ray diffraction.

A New Triterpene from Cynanchum forrestii

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Chinese Chemical Letters 2006年第12期17卷 1569-1572页

作者： Yue LIU Jing QU Shi Shan YU Jing LIU You Cai HU Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine Ministry of Education ＆ Institute of Materia Medica Peking Union Medical College and Chinese Academy of Medical Sciences Beijing 100050

A new triterpene, named cynanotriterpene A, with a ring-A-fission （3, 4-seco） and 13, 27-cyclours-3-oic acid methyl ester skeleton was isolated from the roots of Cynanchum forrestii Schlechter. The structure of the ... 详细信息

关键词： Cynanchumforrestii triterpene x-ray diffraction.

Coupling Reaction of 4-Chloro-7-H-Pyrrolo[2,3-d]Pyrimidine with 2,3,5-Tri-O-Acetyl-b-D-Ribofuranosyl Chloride

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Chinese Chemical Letters 2001年第5期12卷 391-394页

作者： Yun Long ZHANG Liang Ren ZHANG Zhen Jun YANG Ji Mei MIN Li He ZHANG Yang LU Ning Bo GONG Qi Tai ZHENG National Research Laboratory of Natural and Biomimetic Drugs Peking UniversityBeijing 100083 Institue of Materia Medica Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050

Coupling reaction of 4-chloro-7-H-pyrrolo[2,3-d]pyrimidine with 2,3,5-tri-O-acetyl -β-D-ribofuranosyl chloride under the basic condition was investigated. An abnormal coupling reaction, in which the heterocyclic base attacked at the carbon of 1,2-O-methylidene moiety instead of anomeric carbon of ribose was observed and the structure of products 5a, 5b were identified by NMR and x-ray diffraction.

关键词： Chloropyrrolo[2 3-d]pyrimidine 1-chloro-2 3 5-tri-O-acetyl-D-ribofuranose neigh-boring participation effect x-ray diffraction.

A New Occurrence of （Gold-Bearing） Graphite in the Assosa Region, BenishanguI-Gumuz State, W Ethiopia

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Journal of Earth Science and Engineering 2015年第7期5卷 417-435页

作者： Liam A. Bullock Owen J. Morgan School of Geoscienees University of Aberdeen Aberdeen AB24 3UE United Kingdom Tactical Environmental Response Yorkshire LS29 9BZ United Kingdom

The Assosa region of western Ethiopia hosts newly discovered and potentially highly economic graphite-bearing schist units. Due to its unique physical and chemical properties, graphite is quickly becoming an increasingly important economic resource. Graphite occurs over much of the area, and is hosted predominantly by quartz-graphitic schist, quartz-feldspar-mica schist and quartzite. The quartz-graphitic schist covers an area of 37 km2, forming steep valleys and ridges across a 190 km long belt. Graphite is texturally-variable within and across units. Crystal habit varies from highly crystalline to irregular flakes. Flake sizes range from amorphous and crystalline small flake to coarse large flake （〉 150 p.m）, with beneficiation of- 70% and yield potential of 〉 95% （froth flotation methods）. The license area is already a well-known gold-hosting area, and potentially economic gold deposits occur within the graphite-bearing units. Overall, the site shows excellent geochemical indicators, field observations and historical accounts of high gold content. It is suggested that textural variations may be the product of （1） early in-situ formation during （early- to late-Proterozoic） prograde metamorphism and （2） later vein-type mineralization during retrograde metamorphism. The discovery of graphite in western Ethiopia is the first documented and preliminary studies suggest a high economic potential for the deposits.

关键词： Graphite gold metamorphism x-ray fluorescence x-ray diffraction.

Effects of Pb-Doping on Phase Structural and Optical Properties of CdZnS Nano-Powders

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Journal of Electronic Science and Technology 2013年第3期11卷 322-328页

作者： Mahdi Ghasemifard Somayeh Tohidi Roholah Karimzadeh the Nano Technology Lab Esfarayen University the Department of physics Shahid Beheshti University

Cadmium zinc lead sulfide [Cd0.8（Zn1-x7,Pbx）0.2S] nano-powders were prepared by an improved coprecipitation method. The effect of Pb2＋ concentration at 500℃ on the phase and crystalline structure of the Cd0.8（Zn1-x7,Pbx）0.2S powders were investigated by x-ray diffraction.（xRD）. According to the transmission electron microscopy （TEM） images, the particles size are in the range of 58 nm to 72 nm. In addition, optical band gap energy and optical constants of nano-powders were determined using the ultraviolet （UV） spectrum, Fournier transform infrared spectroscopy （FTIR）, and Kramers-Kronig analysis, respectively. We calculate the refractive index n, extinction coefficient k, and dielectric function t as a function of the wavenumber. The experiment results demonstrate that the amount of Pb＋2 has been playing an increasingly important role on optical properties of CZPS nanocrystals.

关键词： Index Terms-Coprecipitation Kramers-Kroniganalysis optical constants x-ray diffraction.