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Superhard and Superconducting B6C
Superhard and Superconducting B6C Kang Xia a, Mengdong Ma b, Cong Liu a, Hao Gao a, Qun Chen a, Julong He b, Jian Sun a,*, Hui-Tian Wang a, Yongjun Tian b, and Dingyu Xing a a National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China b State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China ABSTRACT Crystal structure searching and ab initio calculations have been used here to explore low-energy structures of boron carbides under high pressure. Under pressures of 85–110 GPa, a metastable B6C with R3 m symmetry is found to be energetically more stable than the mixture of previous B4C and elemental boron. This B6C is a rhombohedral structure and contains mooncake-like B24 clusters with stuffing of C2 pairs. The mechanical and dynamical stabilities of this structure at ambient pressure are confirmed by its elastic constants and phonon dispersions. The bulk modulus and shear modulus of this newly predicted B6C at ambient pressure reach high values of 291 GPa and 272 GPa, respectively. The Vickers hardness is calculated to be around 48 GPa, and its melting temperature at ambient pressure is estimated to be around 2500 K, indicating that this metastable B6C is a potential superhard material with very good thermal stability. Interestingly, this superhard B6C structure is also found to be superconducting and its superconducting critical temperature (Tc) is evaluated to be around 12.5 K at ambient pressure by electron-phonon coupling. * Corresponding author. E-mail address: [email protected] 1. -
Densifying Metal Hydrides with High Temperature and Pressure
3,784,682 United States Patent Office Patented Jan. 8, 1974 feet the true density. That is, by this method only theo- 3,784,682 retical or near theoretical densities can be obtained by DENSIFYING METAL HYDRIDES WITH HIGH making the material quite free from porosity (p. 354). TEMPERATURE AND PRESSURE The true density remains the same. Leonard M. NiebylsM, Birmingham, Mich., assignor to Ethyl Corporation, Richmond, Va. SUMMARY OF THE INVENTION No Drawing. Continuation-in-part of abandoned applica- tion Ser. No. 392,370, Aug. 24, 1964. This application The process of this invention provides a practical Apr. 9,1968, Ser. No. 721,135 method of increasing the true density of hydrides of Int. CI. COlb 6/00, 6/06 metals of Groups II-A, II-B, III-A and III-B of the U.S. CI. 423—645 8 Claims Periodic Table. More specifically, true densities of said 10 metal hydrides may be substantially increased by subject- ing a hydride to superatmospheric pressures at or above ABSTRACT OF THE DISCLOSURE fusion temperatures. When beryllium hydride is subjected A method of increasing the density of a hydride of a to this process, a material having a density of at least metal of Groups II-A, II-B, III-A and III-B of the 0.69 g./cc. is obtained. It may or may not be crystalline. Periodic Table which comprises subjecting a hydride to 15 a pressure of from about 50,000 p.s.i. to about 900,000 DESCRIPTION OF THE PREFERRED p.s.i. at or above the fusion temperature of the hydride; EMBODIMENT i.e., between about 65° C. -
UNITED STATES PATENT Office SVEND S
Patented May 24, 1932 1,859,998 UNITED STATES PATENT oFFICE SVEND S. SVENDSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO CLAY REDUCTION comi PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIs . HYDRATED SILICA No Drawing. Application filed December 23, 1927. Serial No. 242,291. This invention relates to the production of silicofluoride is also volatilized and collected hydrated silica from a silicious material such in aqueous animonia. The volatilization oc as silica and silicates generally. - - - - curs about 300 C. The following reactions According to the invention the silicious take place in the aqueous ammonia at tem 5 material is treated with ammonium fluoride peratures below 34 C.: 5 5 or bifluoride and silicon ammonia fluorine compounds are produced. These compounds 2SiF(NH) +2H.O= are volatilized and converted into hydrated (NH4)2SiFs--SiO, (hydrated) + silica by the action of water and ammonia. 2NH.F. (IV) O Metallic silicates or substances containing (NH)SiF+4NH,+2HO = them can be subjected to this treatment di SiO, (hydrated) + 6NH.F. (V) rectly. In treating silica in the form of quartz it is found to be necessary to subject It is thus apparent that O heating the it to a preliminary treatment in order to fa silicious material with the ammonium-flu cilitate the action of the ammonium fluoride oride, ammonia-silicon-fluorine compounds a or bifluoride thereon. A suitable preliminary are formed, and by employing suitable tem treatment is to heat the quartz to a bright red peratures are volatilized from the reaction heat and suddenly cool it by immersion in mixture. These compounds may be silicon water. -
Germane Facts About Germanium Sesquioxide: I. Chemistry and Anticancer Properties
THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE Volume 10, Number 2, 2004, pp. 337–344 ©Mary Ann Liebert, Inc. Germane Facts About Germanium Sesquioxide: I. Chemistry and Anticancer Properties BONNIEJ. KAPLAN, Ph.D., 1 W. WESLEYPARISH, Ph.D., 2 G. MERRILLANDRUS, Ph.D., 2 J. STEVENA. SIMPSON, Ph.D., M.D., 3 and CATHERINEJ. FIELD, Ph.D., R.D. 4 ABSTRACT This paper reviews the history, chemistry, safety, toxicity, and anticancer effects of the organogermanium compound bis (2-carboxyethylgermanium) sesquioxide (CEGS). A companion review follows, discussing the inaccuracies in the scientific record that have prematurely terminated research on clinical uses of CEGS. CEGS is a unique organogermanium compound first made by Mironov and coworkers in Russia and, shortly there- after, popularized by Asai and his colleagues in Japan. Low concentrations of germanium occur in nearly all soils, plants and animal life; natural occurrence of the CEGS form is postulated but not yet demonstrated. The literature demonstrating its anticancer effect is particularly strong: CEGS induces interferon- g (IFN-g), en- hances natural killer cell activity, and inhibits tumor and metastatic growth—effects often detectable after a single oral dose. In addition, oral consumption of CEGS is readily assimilated and rapidly cleared from the body without evidence of toxicity. Given these findings, the absence of human clinical trials of CEGS is un- expected. Possible explanations of why the convincing findings from animal research have not been used to support clinical trials are discussed. Clinical trials on CEGS are recommended. INTRODUCTION bispropionic acid; 3-oxygermylpropionic acid polymer; poly- trans-(2-carboxyethyl) germasesquioxane); proxigerma- n general, dietary supplements are an underinvestigated nium; repagermanium; and Serocion. -
Elemental Fluorine Product Information (Pdf)
Elemental Fluorine Contents 1 Introduction ............................................................................................................... 4 2.1 Technical Application of Fluorine ............................................................................. 5 2.2 Electronic Application of Fluorine ........................................................................... 7 2.3 Fluorine On-Site Plant ............................................................................................ 8 3 Specifications ............................................................................................................ 9 4 Safety ...................................................................................................................... 10 4.1 Maintenance of the F2 system .............................................................................. 12 4.2 First Aid ................................................................................................................ 13 5.1 Chemical Properties ............................................................................................. 14 5.2 Physical Data ....................................................................................................... 15 6 Toxicity .................................................................................................................... 18 7 Shipping and Transport ........................................................................................... 20 8 Environment ........................................................................................................... -
New Generation Cadmium‑Free Quantum Dots for Biophotonics and Nanomedicine
This document is downloaded from DR‑NTU (https://dr.ntu.edu.sg) Nanyang Technological University, Singapore. New Generation Cadmium‑Free Quantum Dots for Biophotonics and Nanomedicine Xu, Gaixia; Zeng, Shuwen; Zhang, Butian; Swihart, Mark T.; Yong, Ken‑Tye; Prasad, Paras N. 2016 Xu, G., Zeng, S., Zhang, B., Swihart, M. T., Yong, K.‑T., & Prasad, P. N. (2016). New Generation Cadmium‑Free Quantum Dots for Biophotonics and Nanomedicine. Chemical Reviews, 116(19), 12234‑12327. https://hdl.handle.net/10356/83973 https://doi.org/10.1021/acs.chemrev.6b00290 © 2016 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by Chemical Reviews, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1021/acs.chemrev.6b00290]. Downloaded on 06 Oct 2021 00:28:06 SGT Page 1 of 288 Submitted to Chemical Reviews 1 2 3 4 5 6 New Generation Cadmium-Free Quantum Dots for 7 8 Biophotonics and Nanomedicine 9 10 11 12 13 14 Gaixia Xu1,5†, Shuwen Zeng2,5†, Butian Zhang2, Mark T. Swihart3*, 15 2* 4* 16 Ken-Tye Yong and Paras N. Prasad 17 18 19 20 1 21 Key Laboratory of Optoelectronics Devices and Systems of Ministry of Education/Guangdong 22 Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, P. R. 23 China 24 2 25 School of Electrical and Electronic Engineering, -
Nigam Prasad Rath Research Professor
Nigam Prasad Rath Research Professor Department of Chemistry and Biochemistry University of Missouri - St. Louis One University Boulevard St. Louis, MO 63121. E-mail: [email protected] Phone: 314-516-5333 FAX: 314-516-5342 Education : B. Sc.(Honors) : 1st Class Honors in Chemistry with Distinction, Berhampur University, Berhampur, India, 1977. M. Sc. (Chemistry): 1st Class, Berhampur University, Berhampur, India, 1979. Ph. D. (Chemistry): Oklahoma State University, Stillwater, OK, USA, 1985. Professional Experience: Research Professor , Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO, 2004 to present. Research Associate Professor , Department of Chemistry, University of Missouri, St. Louis, MO, 1997 to 2004. Research Assistant Professor , Department of Chemistry, University of Missouri, St. Louis, MO, 1989 to 1996. Assistant Faculty Fellow , Department of Chemistry, University of Notre Dame, Notre Dame, IN 1987 to 1989. Post Doctoral Research Associate , Department of Chemistry, University of Notre Dame, Notre Dame, IN 1986-87. Graduate Assistant , Department of Chemistry, Oklahoma State University, Stillwater, OK 1982 to 1985. Junior Research Fellow (CSIR) , Department of Chemistry, Indian Institute of Technology, Kharagpur, India, 1981-82. Junior Research Fellow , Department of Chemistry, Indian Institute of Technology, Kanpur, India, 1979 to 1981. 2 Professional Positions: Visiting Scientist, Monsanto Corporate Research, Chesterfield, MO, 1992 to 1994. Scientific Consultant, Regional Research Laboratory, Trivandrum, India, 1992 to present. Assistant Professor, Evening College, University of Missouri, St. Louis, 1992 to 2000. Research Mentor, Engelmann Mathematics and Science Institute, University of Missouri, St. Louis, 1990 to 1998. Research Mentor, NSF STARS Program, University of Missouri, St. Louis, 1999 to present. Honors and Awards: National Merit Scholarship, India, 1977-79. -
Volumetric Determination of Boron in Boron Carbide V
B. A. R. C.-1017 ei GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION VOLUMETRIC DETERMINATION OF BORON IN BORON CARBIDE V. K. Manchanda and M. S. Subramanian Radiochemistry Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY, INDIA 1979 B. A. R.C.-1017 GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION U erf < ffl VOLUMETRIC DETERMINATION OF BORON IN BORON CARBIDE by V.K. Manchanda and M. S. Subramantan Radlochernlstry Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY, INDIA 1979 INIS Subject Category : Bll Descriptor a : BORON CARBIDES BORON QUANTITATIVE CHEMICAL ANALYSIS TITRATION ACCURACY ABSTRACT Boron carbide is used for oontrol rods and as a shielding material In nuclear reactors. As such, the boron carbide must conform to rigid chemical specifications. Impurities present have a significant effect on the life time of the control rods under conditions of high temperature and i neutron flux. Therefore, methods for the accurate determination of the various constituents in boron carbide is of utmost importance. This-report discusses p\volumetric procedure for i •_ . •' i : ((.•>;•" ••%. the, determination of boron content In boron carbide/ '•••>',••. A VOLtCIKTRIC DET3SIINATI0N 0? BCRON IN BORON CAR3IDE by V.K. Jfenchanda and M.S. Subramanian IU7R0DVCT10N Boron carbide is an important nuclear material a.3 it is used in nuclear reactors for control rods and as a shielding material « Preparation of boron carbide yields a product often contaminated with either unreacted carbon or boric acid. These impurities affect the physical, chemical and neutron absorption properties of the material, Particularly under conditions of high temperature and neutron flux in a reactor, tlie life time of the control rods depends on its composition. -
INFORMATION to USERS the Most Advanced Technology Has Been
INFORMATION TO USERS The most advanced technology has been used to photo graph and reproduce this manuscript from the microfilm master. UMI films the original text directly from the copy submitted. Thus, some dissertation copies are in typewriter face, while others may be from a computer printer. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyrighted material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are re produced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each oversize page is available as one exposure on a standard 35 mm slide or as a 17" x 23" black and white photographic print for an additional charge. Photographs included in the original manuscript have been reproduced xerographically in this copy. 35 mm slides or 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Accessing the World'sUMI Information since 1938 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA Order Number 8820378 Stereochemical studies in anaerobic metabolism Zydowsky, Lynne Douthit, Ph.D. The Ohio State University, 1988 UMI 300 N. Zeeb Rd. Ann Aibor, M I 48106 PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V . -
Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry
REVIEWS Wherefore Art Thou Copper? Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry Eiichi Nakamura* and Seiji Mori Organocopper reagents provide the principles. This review will summarize example of molecular recognition and most general synthetic tools in organic first the general structural features of supramolecular chemistry, which chemistry for nucleophilic delivery of organocopper compounds and the pre- chemists have long exploited without hard carbanions to electrophilic car- vious mechanistic arguments, and then knowing it. Reasoning about the bon centers. A number of structural describe the most recent mechanistic uniqueness of the copper atom among and mechanistic studies have been pictures obtained through high-level neighboring metal elements in the reported and have led to a wide variety quantum mechanical calculations for periodic table will be presented. of mechanistic proposals, some of three typical organocuprate reactions, which might even be contradictory to carbocupration, conjugate addition, Keywords: catalysis ´ conjugate addi- others. With the recent advent of and SN2 alkylation. The unified view tions ´ copper ´ density functional physical and theoretical methodolo- on the nucleophilic reactivities of met- calculations ´ supramolecular chemis- gies, the accumulated knowledge on al organocuprate clusters thus ob- try organocopper chemistry is being put tained has indicated that organocup- together into a few major mechanistic rate chemistry represents an intricate 1. Introduction 1 R Cu X The desire to learn about the nature of elements has been R or R1 R and will remain a main concern of chemists. In this review, we R Cu will consider what properties of copper make organocopper R1 chemistry so useful in organic chemistry. -
The Photochemistry of Some Acyclic Ketones Containing a Silicon Or a Tin Atom
University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Summer 1965 THE PHOTOCHEMISTRY OF SOME ACYCLIC KETONES CONTAINING A SILICON OR A TIN ATOM PERRY LESTER MAXFIELD Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation MAXFIELD, PERRY LESTER, "THE PHOTOCHEMISTRY OF SOME ACYCLIC KETONES CONTAINING A SILICON OR A TIN ATOM" (1965). Doctoral Dissertations. 816. https://scholars.unh.edu/dissertation/816 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. This dissertation has been microfilmed exactly as received 6 6-5974 MAXFIELD, Perry Lester, 1933- THE PHOTOCHEMISTRY OF SOME ACYCLIC KETONES CONTAINING A SILICON OR A TIN ATOM. University of New Hampshire, Ph.D., 1965 Chemistry, organic University Microfilms, Inc., Ann Arbor, Michigan THE PHOTOCHEMISTRY OF SOME ACYCLIC KETONES CONTAINING A SILICON OR A TIN ATOM BY PERRY LESTER MAXFIELD B. S., Brigham Young University, 1961 A THESIS Submitted to the University of New Hampshire In Partial Fulfillment of The Requirements for the Degree of Doctor of Philosophy Graduate School Department of Chemistry August, 1964 This thesis has been examined and approved. Date ACKNOWLEDGMENT I wish to express my gratitude to the Department of Chemistry of the University of New Hampshire for the help and guidance which I have received during my stay here. Acknowledg ment is also due the United States Department of Health, Edu cation, and Welfare for a National Defense Education Fellow ship which has been so helpful in financing the three years of study. -
Isomorphous Substitution of Aluminium for Silicon in Tobermoritic Structure
Isomorphous Substitution of Aluminium for Silicon in Tobermoritic Structure. I. The Mixtures of Different Forms of Silicon Dioxide and of Different Compounds of Aluminium J. PETROVIÖ, V. RUSNÁK and L. ŠTEVULA Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava 9 Received July 2, 1968 The isomorphous substitution of Al(III) for Si(IV) in tobermoritic structure was examined by X-ray phase analysis and DTA. It has been found that the extent of the substitution depends on the materials used. The samples were prepared using different forms of silica-either ^-quartz, quartz-glass, Si02-gel or aerosil. Gibbsite, boehmite, dehydrated kaolinite, kaolinite, corundum and 7-AI2O3 were used as sources of aluminium. The samples were heated in an autoclave at 150, 180 and 200°C for 10, 24 and in some cases for 48 hours. Tobermorite can be synthesized from calcium oxide and silica under hydrothermal conditions. Up to temperatures of about 110°C it is stable, at higher temperatures and under hydrothermal conditions it is formed as an unstable compound. When the reaction is allowed to proceed for a longer time, or when it takes place at higher tem perature, another stable calcium hydrosilicate arises. At lower temperature a calcium hydrosilicate with tobermoritic structure is formed. It has been found that tobermori te is produced on autoclaving building materials containing lime and some materials with high SÍO2 content. It is also formed from anhydrous dicalcium silicates in the course of setting of cement. Under different conditions, compounds with tobermoritic structure arise which, however, differ in the amount or lime and water in the molecu le, as well as in the arrangement of the structure — e.g.