WorldWideScience

Sample records for calcium halides

  1. The Antimicrobial Action of Silver Halides in Calcium Phosphate

    OpenAIRE

    Kalniņa, D; Gross, K; Onufrijevs, P.; Daukšta, E; Nikolajeva, V; Stankeviciute, Z; Kareiva, A.

    2015-01-01

    Silver halides represent a yet unexplored avenue for imparting antimicrobial activity to calcium phosphates. Negtively charged silver halide colloids (AgI, AgBr and AgCl) were added to synthesized amorphous calcium phosphate. Concurrent melting of silver halides and crystallization to carbonated apatite at 700 oC increased the silver halide surface area available to bacteria and formed a lower solubility apatite. The effect of the matrix solubility on antimicrobial response could ...

  2. Effect of replacing calcium oxide with calcium halide on crystallization and some physical properties of calcium vanadium phosphate glass ceramics

    International Nuclear Information System (INIS)

    The effect of halide ions on density, electrical, magnetic and crystallization kinetics for (20X-50P2O5-30V2O5) mole% has been investigated, where X=CaO, CaF2, CaCl2 and CaBr2. Halide ions reduce the glass transition temperature, crystallization temperature and activation energy of crystallization. Density, electrical conductivity and magnetic susceptibility increase while molar volume, glass thermal stability and interatomic distance between transition metal ions decrease as the halide ions replace the oxygen ions in these glasses. -- Research Highlights: → Replacing oxygen ions by halide ions decreases glass transition temperature and thermal stability. → Replacing oxygen ions by halide ions increases electrical conductivity and decreases activation energy. → Replacing oxygen ions by halide ions enhances the tendency of glass ceramic and decreases the crystallization activation energy.

  3. Effect of replacing calcium oxide with calcium halide on crystallization and some physical properties of calcium vanadium phosphate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Assem, E.E., E-mail: e_assem_2000@sci.kfs.edu.e [Physics Department, Faculty of Science, Kafrelsheikh University, Kafrelsheikh (Egypt)

    2011-02-01

    The effect of halide ions on density, electrical, magnetic and crystallization kinetics for (20X-50P{sub 2}O{sub 5}-30V{sub 2}O{sub 5}) mole% has been investigated, where X=CaO, CaF{sub 2}, CaCl{sub 2} and CaBr{sub 2}. Halide ions reduce the glass transition temperature, crystallization temperature and activation energy of crystallization. Density, electrical conductivity and magnetic susceptibility increase while molar volume, glass thermal stability and interatomic distance between transition metal ions decrease as the halide ions replace the oxygen ions in these glasses. -- Research Highlights: {yields} Replacing oxygen ions by halide ions decreases glass transition temperature and thermal stability. {yields} Replacing oxygen ions by halide ions increases electrical conductivity and decreases activation energy. {yields} Replacing oxygen ions by halide ions enhances the tendency of glass ceramic and decreases the crystallization activation energy.

  4. A study of some calcium dihalides and strontium fluoride halides systems

    International Nuclear Information System (INIS)

    The CaX2-CaY2 and SrF2-SrX2 (where X and Y represent halide anions) systems were investigated by the Guinier powder X-ray diffraction technique. In the calcium dihalide systems only solid solutions were found. In the strontium fluoride - strontium chloride and strontium fluoride - strontium bromide systems the dihalides and the PbFCl-type SrFX phases were observed. The preparation, crystallographic data and atom distribution of the mixed halides, SrFCl/sub 0.5/Br/sub 0.5/, Ca/sub 0.5/Sr/sub 0.5/FCl, Ca/sub 0.5/Yb/sub 0.5/FCl and Sr/sub 0.5/Eu/sub 0.5/FBr are presented and discussed. (author)

  5. UV and X radiation effects on the stability of calcium halide phosphate phosphors. 1

    International Nuclear Information System (INIS)

    Intensity losses of several calcium halide phosphate phosphors have been investigated as a function of the time of irradiation with near UV and X radiation. The results show that antimony-containing foreign phases increase such losses. The directly excited manganese centre emission is much more lowered than the sensitized one. Detrimental effects of the 185 nm UV radiation are observable not only in the first minutes of irradiation but also over considerably extended periods. The sensitization effect caused by irradiation in different gases depends on the phosphor, especially on the content of antimony, and can be explained by the sorption of gaseous impurities at the phosphor surface so that the diffusion of photochemical reaction products from the surface is inhibited

  6. Calcium looping process for high purity hydrogen production integrated with capture of carbon dioxide, sulfur and halides

    Energy Technology Data Exchange (ETDEWEB)

    Ramkumar, Shwetha; Fan, Liang-Shih

    2015-11-04

    A process for producing hydrogen comprising the steps of: (i) gasifying a fuel into a raw synthesis gas comprising CO, hydrogen, steam, sulfur and halide contaminants in the form of H.sub.2S, COS, and HX, wherein X is a halide; (ii) passing the raw synthesis gas through a water gas shift reactor (WGSR) into which CaO and steam are injected, the CaO reacting with the shifted gas to remove CO.sub.2, sulfur and halides in a solid-phase calcium-containing product comprising CaCO.sub.3, CaS and CaX.sub.2; (iii) separating the solid-phase calcium-containing product from an enriched gaseous hydrogen product; and (iv) regenerating the CaO by calcining the solid-phase calcium-containing product at a condition selected from the group consisting of: in the presence of steam, in the presence of CO.sub.2, in the presence of synthesis gas, in the presence of H.sub.2 and O.sub.2, under partial vacuum, and combinations thereof.

  7. Calcium looping process for high purity hydrogen production integrated with capture of carbon dioxide, sulfur and halides

    Science.gov (United States)

    Ramkumar, Shwetha; Fan, Liang-Shih

    2013-07-30

    A process for producing hydrogen comprising the steps of: (i) gasifying a fuel into a raw synthesis gas comprising CO, hydrogen, steam, sulfur and halide contaminants in the form of H.sub.2S, COS, and HX, wherein X is a halide; (ii) passing the raw synthesis gas through a water gas shift reactor (WGSR) into which CaO and steam are injected, the CaO reacting with the shifted gas to remove CO.sub.2, sulfur and halides in a solid-phase calcium-containing product comprising CaCO.sub.3, CaS and CaX.sub.2; (iii) separating the solid-phase calcium-containing product from an enriched gaseous hydrogen product; and (iv) regenerating the CaO by calcining the solid-phase calcium-containing product at a condition selected from the group consisting of: in the presence of steam, in the presence of CO.sub.2, in the presence of synthesis gas, in the presence of H.sub.2 and O.sub.2, under partial vacuum, and combinations thereof.

  8. Calcium manganate: A promising candidate as buffer layer for hybrid halide perovskite photovoltaic-thermoelectric systems

    International Nuclear Information System (INIS)

    We have systematically studied the feasibility of CaMnO3 thin film, an n-type perovskite, to be utilized as the buffer layer for hybrid halide perovskite photovoltaic-thermoelectric device. Locations of the conduction band and the valence band, spontaneous polarization performance, and optical properties were investigated. Results indicate the energy band of CaMnO3 can match up well with that of CH3NH3PbI3 on separating electron-hole pairs. In addition, the consistent polarization angle helps enlarge the open circuit voltage of the composite system. Besides, CaMnO3 film shows large absorption coefficient and low extinction coefficient under visible irradiation, demonstrating high carrier concentration, which is beneficial to the current density. More importantly, benign thermoelectric properties enable CaMnO3 film to assimilate phonon vibration from CH3NH3PbI3. All the above features lead to a bright future of CaMnO3 film, which can be a promising candidate as a buffer layer for hybrid halide perovskite photovoltaic-thermoelectric systems

  9. Effect of the calcium halides, CaCl{sub 2} and CaBr{sub 2}, on hydrogen desorption in the Li–Mg–N–H system

    Energy Technology Data Exchange (ETDEWEB)

    Bill, Rachel F. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Reed, Daniel; Book, David [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Anderson, Paul A., E-mail: p.a.anderson@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • H{sub 2} desorption from 2LiNH{sub 2}–MgH{sub 2}–xCaX{sub 2} (x = 0, 0.1, 0.15; X = Cl, Br) samples studied. • Addition of calcium halides reduced the desorption temperature in all samples. • Peak H{sub 2} release was around 150 °C lower in ball-milled than in hand-ground samples. • The 2LiNH{sub 2}–MgH{sub 2}–0.15CaBr{sub 2} sample showed the lowest peak desorption temperature. • CaBr{sub 2} reduced the activation energy to 78.8 kJ mol{sup −1}, 24% less than the undoped sample. - Abstract: Calcium-halide-doped lithium amide–magnesium hydride samples were prepared both by hand-grinding and ball-milling 2LiNH{sub 2}–MgH{sub 2}–xCaX{sub 2} (x = 0, 0.1, and 0.15; X = Cl or Br). The addition of calcium halides reduced the hydrogen desorption temperature in all samples. The ball-milled undoped sample (2LiNH{sub 2}–MgH{sub 2}) began to desorb hydrogen at around 125 °C and peaked at 170 °C. Hydrogen desorption from the 0.15 mol CaCl{sub 2}-containing sample began ca 30 °C lower than that of the undoped sample and peaked at 150 °C. Both the onset and peak temperatures of the CaBr{sub 2} sample (x = 0.15) were reduced by 15 °C compared to the chloride. Kissinger’s method was used to calculate the effective activation energy (E{sub a}) for the systems: E{sub a} for the 0.15 mol CaCl{sub 2}-containing sample was found to be 91.8 kJ mol{sup −1} and the value for the 0.15 mol CaBr{sub 2}-containing sample was 78.8 kJ mol{sup −1}.

  10. Effect of the calcium halides, CaCl2 and CaBr2, on hydrogen desorption in the Li–Mg–N–H system

    International Nuclear Information System (INIS)

    Highlights: • H2 desorption from 2LiNH2–MgH2–xCaX2 (x = 0, 0.1, 0.15; X = Cl, Br) samples studied. • Addition of calcium halides reduced the desorption temperature in all samples. • Peak H2 release was around 150 °C lower in ball-milled than in hand-ground samples. • The 2LiNH2–MgH2–0.15CaBr2 sample showed the lowest peak desorption temperature. • CaBr2 reduced the activation energy to 78.8 kJ mol−1, 24% less than the undoped sample. - Abstract: Calcium-halide-doped lithium amide–magnesium hydride samples were prepared both by hand-grinding and ball-milling 2LiNH2–MgH2–xCaX2 (x = 0, 0.1, and 0.15; X = Cl or Br). The addition of calcium halides reduced the hydrogen desorption temperature in all samples. The ball-milled undoped sample (2LiNH2–MgH2) began to desorb hydrogen at around 125 °C and peaked at 170 °C. Hydrogen desorption from the 0.15 mol CaCl2-containing sample began ca 30 °C lower than that of the undoped sample and peaked at 150 °C. Both the onset and peak temperatures of the CaBr2 sample (x = 0.15) were reduced by 15 °C compared to the chloride. Kissinger’s method was used to calculate the effective activation energy (Ea) for the systems: Ea for the 0.15 mol CaCl2-containing sample was found to be 91.8 kJ mol−1 and the value for the 0.15 mol CaBr2-containing sample was 78.8 kJ mol−1.

  11. Development of a glass-encapsulated calcium phosphate wasteform for the immobilization of actinide and halide containing radioactive wastes from the pyrochemical reprocessing of plutonium metal

    International Nuclear Information System (INIS)

    Chloride-containing radioactive wastes are generated during the pyrochemical reprocessing of Pu metal. Immobilization of these wastes in borosilicate glass or Synroc-type ceramics is not viable due to the very low solubility of chlorides in these hosts. Alternative wasteforms, including zeolites and direct vitrification in phosphate glasses, were therefore studied. However, the preferred option was to immobilize the waste in calcium phosphate ceramics, forming a number of stable mineral phases including chlorapatite, chloride-substituted fluorapatite and spodiosite. The immobilization process developed in this study involves a solid state process in which waste and host powders are reacted in air at temperatures in the range of 700-800 deg. C. The ceramic products obtained by this process are non-hygroscopic free-flowing powders that require encapsulation in glass to produce a monolithic wasteform suitable for storage and ultimate disposal. A suitable relatively low melting temperature phosphate-based glass was identified. Durability trials of both the ceramic powder and sintered glass-ceramic hybrid wasteform indicate that both the halides and actinide surrogate ions are satisfactorily immobilized

  12. The Silver Halides

    Science.gov (United States)

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  13. Method for calcining nuclear waste solutions containing zirconium and halides

    Science.gov (United States)

    Newby, Billie J.

    1979-01-01

    A reduction in the quantity of gelatinous solids which are formed in aqueous zirconium-fluoride nuclear reprocessing waste solutions by calcium nitrate added to suppress halide volatility during calcination of the solution while further suppressing chloride volatility is achieved by increasing the aluminum to fluoride mole ratio in the waste solution prior to adding the calcium nitrate.

  14. Polynuclear technetium halide clusters

    International Nuclear Information System (INIS)

    Development of chemistry of polynuclear technetium halide clusters in works devoted to synthesis, structure and investigation of their chemical and physical properties is considered. The role of academician V.I. Spitsyn as an initiator of investigation of polynuclear technetium halide clusters in the Institute of Physical Chemistry of Academy of Science of USSR is noted. Reactions and stability of cluster halides, their molecular and electronic structures are analyzed. Prospects of development of polynuclear technetium halide clusters chemistry as a direction being on the junction of cluster chemistry and theory of metal-metal multiple bonds are appreciated

  15. Photofragmentation of metal halides

    International Nuclear Information System (INIS)

    The author deals with photodissociation of molecules of alkali halides. It is shown that the total absorption cross section consists of two contributions arising from transitions to excited states of total electronic angular momentum Ω=0+ and Ω=1. From the inversion of the absorption continua potential energy curves of the excited states can be constructed in the Franck-Condon region. It is found that for all alkali halides the 0+ state is higher in energy than the Ω=1 state. Extensive studies are reported on three thallium halides, TlI, TlBr and TlCl at various wavelengths covering the near ultraviolet region. (Auth.)

  16. PREPARATION OF HALIDES OF PLUTONIUM

    Science.gov (United States)

    Garner, C.S.; Johns, I.B.

    1958-09-01

    A dry chemical method is described for preparing plutonium halides, which consists in contacting plutonyl nitrate with dry gaseous HCl or HF at an elevated temperature. The addition to the reaction gas of a small quantity of an oxidizing gas or a reducing gas will cause formation of the tetra- or tri-halide of plutonium as desired.

  17. METHOD OF PREPARING METAL HALIDES

    Science.gov (United States)

    Hendrickson, A.V.

    1958-11-18

    The conversion of plutonium halides from plutonium peroxide can be done by washing the peroxide with hydrogen peroxide, drying the peroxide, passing a dry gaseous hydrohalide over the surface of the peroxide at a temperature of about lOO icient laborato C until the reaction rate has stabillzed, and then ralsing the reaction temperature to between 400 and 600 icient laborato C until the conversion to plutonium halide is substantially complete.

  18. Radiochemical synthesis of pure anhydrous metal halides

    Science.gov (United States)

    Philipp, W. H.; Marsik, S. J.; May, C. E.

    1973-01-01

    Method uses radiation chemistry as practical tool for inorganic preparations and in particular deposition of metals by irradiation of their aqueous metal salt solutions with high energy electrons. Higher valence metal halide is dissolved in organic liquid and exposed to high energy electrons. This causes metal halide to be reduced to a lower valence metal halide.

  19. Preparation of cerium halide solvate complexes

    Science.gov (United States)

    Vasudevan, Kalyan V; Smith, Nickolaus A; Gordon, John C; McKigney, Edward A; Muenchaussen, Ross E

    2013-08-06

    Crystals of a solvated cerium(III) halide solvate complex resulted from a process of forming a paste of a cerium(III) halide in an ionic liquid, adding a solvent to the paste, removing any undissolved solid, and then cooling the liquid phase. Diffusing a solvent vapor into the liquid phase also resulted in crystals of a solvated cerium(III) halide complex.

  20. Electronic conduction in molten halides

    Energy Technology Data Exchange (ETDEWEB)

    Heus, R.J.; Egan, J.J.

    1976-01-01

    Methods of measuring electronic conductivity in molten halides are reviewed. These include increase of total conductivity with addition of metal, polarization techniques, chronopotentiometry, and motion of colored subhalides in a potential gradient. The applicability of the Nernst-Einstein equation and the role of convection are considered. Results are presented for several halide melts. Applications of these results are elucidated, including self-discharge rate of molten salt batteries, measurement of alloy thermodynamics using molten salt electrolytes, and kinetics of tarnishing reactions with formation of liquid films.

  1. Thermodynamic properties of Alkali Halides

    International Nuclear Information System (INIS)

    The method of moments of [1], developed by the authors in [2] for strongly and harmonic crystals with f.c.c. structure is used here to investigate the main thermodynamic properties of the potassium halides. Their analytic expressions as functions of temperature are obtained and the comparison between the theoretical results and the experimental data is made. (author). 22 refs., 5 tabs

  2. Saucy-Marbet Rearrangements of Alkynyl Halides in the Synthesis of Highly Enantiomerically Enriched Allenyl Halides

    OpenAIRE

    Tang, Yu; Shen, Lichun; Dellaria, Becky J.; Richard P. Hsung

    2008-01-01

    A stereospecific Saucy-Marbet rearrangement of alkynyl halides is described here. These rearrangements provide an entry to highly enantiomerically enriched allenyl bromides and chlorides through excellent chirality transfer and the reservation of optical integrity of alkynyl halides.

  3. TRANSURANIC METAL HALIDES AND A PROCESS FOR THE PRODUCTION THEREOF

    Science.gov (United States)

    Fried, S.

    1951-03-20

    Halides of transuranic elements are prepared by contacting with aluminum and a halogen, or with an aluminum halide, a transuranic metal oxide, oxyhalide, halide, or mixture thereof at an elevated temperature.

  4. 40 CFR 721.4095 - Quaternary ammonium alkyltherpropyl trialkylamine halides.

    Science.gov (United States)

    2010-07-01

    ... trialkylamine halides. 721.4095 Section 721.4095 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4095 Quaternary ammonium alkyltherpropyl trialkylamine halides. (a... generically as quaternary ammonium alkyltherpropyl trialkylamine halides (PMNs...

  5. Halogen versus halide electronic structure

    Institute of Scientific and Technical Information of China (English)

    Willem-Jan; van; Zeist; F.Matthias; Bickelhaupt

    2010-01-01

    Halide anions X-are known to show a decreasing proton affinity(PA),as X descends in the periodic table along series F,Cl,Br and I.But it is also well-known that,along this series,the halogen atom X becomes less electronegative(or more electropositive).This corresponds to an increasing energy of the valence np atomic orbital(AO) which,somewhat contradictorily,suggests that the electron donor capability and thus the PA of the halides should increase along the series F,Cl,Br,I.To reconcile these contradictory observations,we have carried out a detailed theoretical analysis of the electronic structure and bonding capability of the halide anions X-as well as the halogen radicals X-,using the molecular orbital(MO) models contained in Kohn-Sham density functional theory(DFT,at SAOP/TZ2P as well as OLYP/TZ2P levels) and ab initio theory(at the HF/TZ2P level).We also resolve an apparent intrinsic contradiction in Hartree-Fock theory between orbital-energy and PA trends.The results of our analyses are of direct relevance for understanding elementary organic reactions such as nucleophilic substitution(SN2) and base-induced elimination(E2) reactions.

  6. Cohesive Energy-Lattice Constant and Bulk Modulus-Lattice Constant Relationships: Alkali Halides, Ag Halides, Tl Halides

    Science.gov (United States)

    Schlosser, Herbert

    1992-01-01

    In this note we present two expressions relating the cohesive energy, E(sub coh), and the zero pressure isothermal bulk modulus, B(sub 0), of the alkali halides. Ag halides and TI halides, with the nearest neighbor distances, d(sub nn). First, we show that the product E(sub coh)d(sub 0) within families of halide crystals with common crystal structure is to a good approximation constant, with maximum rms deviation of plus or minus 2%. Secondly, we demonstrate that within families of halide crystals with a common cation and common crystal structure the product B(sub 0)d(sup 3.5)(sub nn) is a good approximation constant, with maximum rms deviation of plus or minus 1.36%.

  7. Computational screening of mixed metal halide ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich;

    of natural selection. The GA is evolving from an initial (random) population and selecting those with highest fitness, a function based on e.g. stability, release temperature and storage capacity. The search space includes all alkaline, alkaline earth, 3d and 4d metals and the four lightest halides......Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure...

  8. Fullerenes doped with metal halides

    International Nuclear Information System (INIS)

    The cage-like structure of fullerenes is a challenge to every experimental to put something inside - to dope the fullerenes. In fact, the research team that first identified C60 as a football-like molecule quickly succeeded in trapping metal atoms inside and in shrinking the cage around this atom by photofragmentation. In this paper we report the results of ''shrink-wrapping'' the fullerenes around metal halide molecules. Of special interest is the critical size (the minimum number of carbon atoms) that can still enclose the dopant. A rough model for the space available inside a carbon cage gives good agreement with the measured shrinking limits. (author). 8 refs, 6 figs

  9. PREPARATION OF ALKYL HALIDES VIA ORGANOTELLURIUMS

    OpenAIRE

    チカマツ, キヨフミ; オオツボ, テツオ; オグラ, フミオ; ヤマグチ, ハチロウ; Kiyofumi, CHIKAMATSU; Tetsuo, OTSUBO; Fumio, OGURA; Hachiro, YAMAGUCHI

    1982-01-01

    The conversion of phenyltelluroalkanes to haloalkanes was studied in connection with the homologation of alkyl halides. Similar reactions of 1,1-bis(phenyltelluro)alkanes provided a new synthetic method of aldehydes.

  10. Toxicity of organometal halide perovskite solar cells

    Science.gov (United States)

    Babayigit, Aslihan; Ethirajan, Anitha; Muller, Marc; Conings, Bert

    2016-03-01

    In the last few years, the advent of metal halide perovskite solar cells has revolutionized the prospects of next-generation photovoltaics. As this technology is maturing at an exceptional rate, research on its environmental impact is becoming increasingly relevant.

  11. Copper Catalyzed Oceanic Methyl Halide Production

    OpenAIRE

    Robin Kim, Jae Yun; Rhew, Robert

    2014-01-01

    Methyl halides are found in all of Earth’s biomes, produced naturally or through manmade means. Their presence in the atmosphere is problematic, as they catalyze depletion of stratospheric ozone. To understand the full environmental impact of these compounds, it is important to identify their chemical cycling processes. Iron increases methyl halide production in soils and oceans, yet copper’s influence remains unknown despite its similar chemical oxidation properties to iron. I experimentally...

  12. Oxidation of hydrogen halides to elemental halogens

    Science.gov (United States)

    Rohrmann, Charles A.; Fullam, Harold T.

    1985-01-01

    A process for oxidizing hydrogen halides having substantially no sulfur impurities by means of a catalytically active molten salt is disclosed. A mixture of the subject hydrogen halide and an oxygen bearing gas is contacted with a molten salt containing an oxidizing catalyst and alkali metal normal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen and substantially free of sulfur oxide gases.

  13. Calcium - urine

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003603.htm Calcium - urine To use the sharing features on this ... enable JavaScript. This test measures the amount of calcium in urine. All cells need calcium in order ...

  14. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  15. Calcium Oscillations

    OpenAIRE

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlyin...

  16. The Remarkable Reactivity of Aryl Halides with Nucleophiles

    Science.gov (United States)

    Bunnett, Joseph F.

    1974-01-01

    Discusses the reactivity of aryl halides with nucleophilic or basic reagents, including nucleophilic attacks on carbon, hydrogen, halogen, and arynes. Suggestions are made concerning revisions of the sections on aryl halide chemistry courses and the corresponding chapters in textbooks. (CC)

  17. Incidental Polymorphism, Non-Isomorphic and Isomorphic Substitution in Calcium-Valine Coordination Polymers

    OpenAIRE

    Kevin Lamberts; Ulli Englert

    2015-01-01

    Five coordination polymers with the stoichiometry CaX2(valine)2(H2O)2 (X = Cl, Br) were obtained from the corresponding calcium halides and either racemic and enantiopure valine. In all cases the zwitterionic amino acid is exclusively O coordinated and the halides act as counteranions for the resulting one-dimensional cationic chains. The enantiopure chloride shows dimorphism; both forms differ in connectivity from the bromide. In contrast to this structural variability for L-valine, the deri...

  18. Method for recovering hydrocarbons from molten metal halides

    Science.gov (United States)

    Pell, Melvyn B.

    1979-01-01

    In a process for hydrocracking heavy carbonaceous materials by contacting such carbonaceous materials with hydrogen in the presence of a molten metal halide catalyst to produce hydrocarbons having lower molecular weights and thereafter recovering the hydrocarbons so produced from the molten metal halide, an improvement comprising injecting into the spent molten metal halide, a liquid low-boiling hydrocarbon stream is disclosed.

  19. 40 CFR 721.575 - Substituted alkyl halide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted alkyl halide. 721.575... Substances § 721.575 Substituted alkyl halide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as substituted alkyl halide (PMN P-83-1222)...

  20. Harmonic dynamical behaviour of thallous halides

    Indian Academy of Sciences (India)

    Sarvesh K Tiwari; L J Shukla; K S Upadhyaya

    2010-05-01

    Harmonic dynamical behaviour of thallous halides (TlCl and TlBr) have been studied using the new van der Waals three-body force shell model (VTSM), which incorporates the effects of the van der Waals interaction along with long-range Coulomb interactions, three-body interactions and short-range second neighbour interactions in the framework of rigid shell model (RSM). Phonon dispersion curves (PDC), variations of Debye temperature with absolute temperature and phonon density of state (PDS) curves have been reported for thallous halides using VTSM. Comparison of experimental values with those of VTSM and TSM are also reported in the paper and a good agreement between experimental and VTSM values has been found, from which it may be inferred that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behaviour of thallous halides.

  1. Ultraviolet laser ablation of halides and oxides

    International Nuclear Information System (INIS)

    We compare and contrast recent measurements of the behavior of ions and excited ions desorbed from samples of alkali halides and oxide ferroelectrics by an excimer laser at 308 nm wavelength. At the intensities used in these experiments, the density of local electronic excitation is low in the halides and high in the ferroelectrics, corresponding to two- and one-photon band-to-band transitions, respectively. The observed desorption yields and changes in the sample surfaces are discussed in terms of the density of electronic excitation, the relative strengths of electron-lattice coupling, and the role of thermal relaxation processes in the two materials. (orig.)

  2. Computational screening of mixed metal halide ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich; Vegge, Tejs

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure....... In this project we are searching for improved mixed materials with optimal desorption temperatures and kinetics, optimally releasing all ammonia in one step. We apply Density Functional Theory, DFT, calculations on mixed compounds selected by a Genetic Algorithm (GA), relying on biological principles...

  3. The Additive Coloration of Alkali Halides

    Science.gov (United States)

    Jirgal, G. H.; and others

    1969-01-01

    Describes the construction and use of an inexpensive, vacuum furnace designed to produce F-centers in alkali halide crystals by additive coloration. The method described avoids corrosion or contamination during the coloration process. Examination of the resultant crystals is discussed and several experiments using additively colored crystals are…

  4. Computational Screening of Mixed Metal Halide Ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich; Vegge, Tejs

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. In this project we are searching for improved mixed materials with optimal desorption temperature and kinetics. We apply DFT calculations on mixed compounds...

  5. Transport of Soil Halides through Rice Paddies: A Viable Mechanism for Rapid Dispersion of the Soil Halide Reservoir

    Science.gov (United States)

    Redeker, K. R.; Manley, S.; Wang, N.; Cicerone, R.

    2002-05-01

    On short time scales (1-10 years) soil halide concentrations have been assumed to be primarily driven by leaching and deposition processes. Recent results however, have shown that terrestrial plants volatilize soil halides in the form of methyl halides. Emissions of methyl chloride, methyl bromide and methyl iodide represent major pathways for delivery of inorganic halogen radicals to the atmosphere. Inorganic halogen radicals destroy ozone in the stratosphere and modify the oxidative capacity of the lower atmosphere. We have previously shown that rice paddies emit methyl halides and that emissions depend on growth stage of the rice plant as well as field water management. We show here that rice grown in a greenhouse at UCI is capable of volatilizing and/or storing up to 30%, 5%, and 10% of the available chloride, bromide and iodide within the top meter of soil. The percent of plant tissue halide volatilized as methyl halide over the course of the season is calculated to be 0.05%, 0.25% and 85.0% for chloride, bromide and iodide. We compare our greenhouse soil halide concentrations to other commercial rice fields around the world and estimate the e-folding time for soil halides within each region. We suggest that rice agriculture is the driving removal mechanism for halides within rice paddies and that terrestrial plants play a larger role in global cycling of halides than previously estimated.

  6. Flame inhibition by hydrogen halides - Some spectroscopic measurements

    Science.gov (United States)

    Lerner, N. R.; Cagliostro, D. E.

    1973-01-01

    The far-ultraviolet absorption spectrum of an air-propane diffusion flame inhibited with hydrogen halides has been studied. Plots of the absorption of light by hydrogen halides as a function of position in the flame and also as a function of the amount of hydrogen halide added to the flame have been obtained. The hydrogen halides are shown to be more stable on the fuel side of the reaction zone than they are on the air side. Thermal diffusion is seen to be important in determining the concentration distribution of the heavier hydrogen halides in diffusion flames. The relationship between the concentration distribution of the hydrogen halides in the flame and the flame inhibition mechanism is discussed.

  7. Lanthanide-halide based humidity indicators

    Science.gov (United States)

    Beitz, James V.; Williams, Clayton W.

    2008-01-01

    The present invention discloses a lanthanide-halide based humidity indicator and method of producing such indicator. The color of the present invention indicates the humidity of an atmosphere to which it is exposed. For example, impregnating an adsorbent support such as silica gel with an aqueous solution of the europium-containing reagent solution described herein, and dehydrating the support to dryness forms a substance with a yellow color. When this substance is exposed to a humid atmosphere the water vapor from the air is adsorbed into the coating on the pore surface of the silica gel. As the water content of the coating increases, the visual color of the coated silica gel changes from yellow to white. The color change is due to the water combining with the lanthanide-halide complex on the pores of the gel.

  8. Computational Screening of Mixed Metal Halide Ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich;

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. In this project we are searching for improved mixed materials with optimal desorption temperature and kinetics. We apply DFT calculations on mixed compounds...... selected by a Genetic Algorithm (GA), relying on biological principles of natural selection. The GA is evolving from an initial (random) population and selecting those with highest fitness, e.g. stability, release temperature and storage capacity. The search space includes all alkaline, alkaline earth, 3d...... and 4d metals and the four lightest halides, giving in total almost two million combinations....

  9. Process and composition for drying of gaseous hydrogen halides

    Science.gov (United States)

    Tom, Glenn M.; Brown, Duncan W.

    1989-08-01

    A process for drying a gaseous hydrogen halide of the formula HX, wherein X is selected from the group consisting of bromine, chlorine, fluorine, and iodine, to remove water impurity therefrom, comprising: contacting the water impurity-containing gaseous hydrogen halide with a scavenger including a support having associated therewith one or more members of the group consisting of: (a) an active scavenging moiety selected from one or more members of the group consisting of: (i) metal halide compounds dispersed in the support, of the formula MX.sub.y ; and (ii) metal halide pendant functional groups of the formula -MX.sub.y-1 covalently bonded to the support, wherein M is a y-valent metal, and y is an integer whose value is from 1 to 3; (b) corresponding partially or fully alkylated compounds and/or pendant functional groups, of the metal halide compounds and/or pendant functional groups of (a); wherein the alkylated compounds and/or pendant functional groups, when present, are reactive with the gaseous hydrogen halide to form the corresponding halide compounds and/or pendant functional groups of (a); and M being selected such that the heat of formation, .DELTA.H.sub.f of its hydrated halide, MX.sub.y.(H.sub.2 O).sub.n, is governed by the relationship: .DELTA.H.sub.f .gtoreq.n.times.10.1 kilocalories/mole of such hydrated halide compound wherein n is the number of water molecules bound to the metal halide in the metal halide hydrate. Also disclosed is an appertaining scavenger composition and a contacting apparatus wherein the scavenger is deployed in a bed for contacting with the water impurity-containing gaseous hydrogen halide.

  10. Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

    OpenAIRE

    Andrew Tigchelaar; William Tam

    2012-01-01

    Iridium-catalyzed intramolecular [4 + 2] cycloadditions of diene-tethered alkynyl halides were investigated by using [IrCl(cod)]2 as catalyst, and dppe was found to be the most suitable phosphine ligand for the reaction. No oxidative insertion of the iridium into the carbon–halide bond was observed, and the reactions proceeded to provide the halogenated cycloadducts in good yield (75–94%). These results are the first examples of cycloadditions of alkynyl halides using an iridium c...

  11. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  12. Mechanism and Selectivity in Nickel-Catalyzed Cross-Electrophile Coupling of Aryl Halides with Alkyl Halides

    OpenAIRE

    Biswas, Soumik; Weix, Daniel J.

    2013-01-01

    The direct cross-coupling of two different electrophiles, such as an aryl halide with an alkyl halide, offers many advantages over conventional cross-coupling methods that require a carbon nucleophile. Despite its promise as a versatile synthetic strategy, a limited understanding of the mechanism and origin of cross selectivity has hindered progress in reaction development and design. Herein, we shed light on the mechanism for the nickel-catalyzed cross-electrophile coupling of aryl halides w...

  13. Making and Breaking of Lead Halide Perovskites

    KAUST Repository

    Manser, Joseph S.

    2016-02-16

    A new front-runner has emerged in the field of next-generation photovoltaics. A unique class of materials, known as organic metal halide perovskites, bridges the gap between low-cost fabrication and exceptional device performance. These compounds can be processed at low temperature (typically in the range 80–150 °C) and readily self-assemble from the solution phase into high-quality semiconductor thin films. The low energetic barrier for crystal formation has mixed consequences. On one hand, it enables inexpensive processing and both optical and electronic tunability. The caveat, however, is that many as-formed lead halide perovskite thin films lack chemical and structural stability, undergoing rapid degradation in the presence of moisture or heat. To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice of solvent treatment. Proper characterization and tuning of processing parameters can aid in rational optimization of perovskite devices. Likewise, gaining a comprehensive understanding of the degradation mechanism and identifying components of the perovskite structure that may be particularly susceptible to attack by moisture are vital to mitigate device degradation under operating conditions. This Account provides insight into the lifecycle of organic–inorganic lead halide perovskites, including (i) the nature of the precursor solution, (ii) formation of solid-state perovskite thin films and single crystals, and (iii) transformation of perovskites into hydrated phases upon exposure to moisture. In particular, spectroscopic and structural characterization techniques shed light on the thermally driven evolution of the perovskite structure. By tuning precursor stoichiometry and chemistry, and thus the lead halide charge-transfer complexes present in solution, crystallization

  14. Making and Breaking of Lead Halide Perovskites.

    Science.gov (United States)

    Manser, Joseph S; Saidaminov, Makhsud I; Christians, Jeffrey A; Bakr, Osman M; Kamat, Prashant V

    2016-02-16

    A new front-runner has emerged in the field of next-generation photovoltaics. A unique class of materials, known as organic metal halide perovskites, bridges the gap between low-cost fabrication and exceptional device performance. These compounds can be processed at low temperature (typically in the range 80-150 °C) and readily self-assemble from the solution phase into high-quality semiconductor thin films. The low energetic barrier for crystal formation has mixed consequences. On one hand, it enables inexpensive processing and both optical and electronic tunability. The caveat, however, is that many as-formed lead halide perovskite thin films lack chemical and structural stability, undergoing rapid degradation in the presence of moisture or heat. To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice of solvent treatment. Proper characterization and tuning of processing parameters can aid in rational optimization of perovskite devices. Likewise, gaining a comprehensive understanding of the degradation mechanism and identifying components of the perovskite structure that may be particularly susceptible to attack by moisture are vital to mitigate device degradation under operating conditions. This Account provides insight into the lifecycle of organic-inorganic lead halide perovskites, including (i) the nature of the precursor solution, (ii) formation of solid-state perovskite thin films and single crystals, and (iii) transformation of perovskites into hydrated phases upon exposure to moisture. In particular, spectroscopic and structural characterization techniques shed light on the thermally driven evolution of the perovskite structure. By tuning precursor stoichiometry and chemistry, and thus the lead halide charge-transfer complexes present in solution, crystallization

  15. Efficient destruction of CF4 through in situ generation of alkali metals from heated alkali halide reducing mixtures.

    Science.gov (United States)

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

    Perfluorocarbons (PFCs) are the most potent green house gases that are very recalcitrant at destruction. An effective way of converting PFCs using hot solid reagents into safe products has been recently introduced. By investigating the thermal reductive destruction of tetrafluoromethane (CF4) we provided new insight and more physicochemical consideration on this novel process. The complete destruction of CF4was successfully achieved by flowing the gas through a heated reagent bed (400-950 degrees C) that contained powder mixtures of alkali halides, CaO, and Si. The silicon acted as a reducing agent of alkali halides for the in-situ production of alkali metals, and the calcium oxide played the role of a halide ion acceptor. The absence of any single component in this ternary mixture drastically reduced the destruction efficiency of CF4. The CF4 destruction efficiencies with the solid reagent containing the alkali halide, MX, increased in the order of Li approximately Na < K < Cs for alkali cations and I < Br < Cl < F for halide anions. This trend agreed with the endothermicity of the alkali metal generation reaction: the higher the endothermicity, the lower the destruction efficiency. Alkali metal generation was indirectly detected by monitoring H2 production from its reaction with water. The production of alkali metals increased with NaF, KF, and CsF in this order. The CsF/CaO/Si system exhibited the complete destruction of CF4 at as low as 600 degrees C. The solid product analysis by X-ray diffraction (XRD) showed the formation of CaF2 and the depletion of Si with black carbon particles formed in the solid reagent residue. No CO/CO2 and toxic HF and SiF4 formation were detected in the exhaust gas. PMID:11944694

  16. The coacervation of aqueous solutions of tetraalkylammonium halides

    International Nuclear Information System (INIS)

    The coacervation of aqueous solutions of tatraalkylammonium halides in the presence of not of inorganic halides and acids has been studied, considering thermodynamic and spectroscopic aspects. The importance of dispersion forces as well as forces resulting from hydrophobic hydration has been assessed. The analogy between these systems and anionic ion exchange resins has been shown especially for Uranium VI extraction

  17. Ultraviolet absorption spectra of mercuric halides.

    Science.gov (United States)

    Templet, P.; Mcdonald, J. R.; Mcglynn, S. P.; Kendrow, C. H.; Roebber, J. L.; Weiss, K.

    1972-01-01

    The gas phase transitions of the mercuric halides were observed in the UV region by operating at temperatures above 400 K and at vapor pressures on the order of 0.5 mm. Spectral features exhibited by the chloride, bromide, and iodide of mercury correlate energetically with bands previously designated as intermolecular charge transfer transitions. The solution spectra of mercuric iodide and deep color of the crystals (if not due to some solid state interactions) indicate that this molecule may also have longer wavelength transitions.

  18. Elastic Properties of Potassium Halides under Pressure

    Institute of Scientific and Technical Information of China (English)

    K.Haddadi; L.Louail; D.Maouche

    2008-01-01

    The moderate-pressure elastic properties of potassium halides KX (X=F, CI, Br) was studied theoretically using the density functional theory (DFT) with normconserving pseudopotentials method. The phase transfor- mation from the B1 phase (NaCl-type structure) to the denser B2 phase (CsCl-type structure) occurred at 7.7, 3.46 and 2.96 GPa for KF, KCl and KBr, respectively. The elastic stiffness coefficients and bulk modulus of these materials were calculated as function of hydrostatic pressure and compared with both the experimental and theoretical values.

  19. Studies of rare gas halide lasers

    OpenAIRE

    Hogan, Daniel Christopher.; Webb, Colin E.; Dr. C. E. Webb

    1983-01-01

    This thesis presents the results of a study of the mechanisms responsible for limiting the laser pulse duration obtainable in xenon chloride lasers which are excited by UV-preionized, self-sustained gas discharges. The xenon chloride laser system, the principal emission band of which is centred around 308 nm, belongs to the class of high pressure gas lasers known as 'rare-gas halides'(RGH). RGH lasers are now well known for their high peak power output at a number of wavelen...

  20. Calcium Carbonate

    Science.gov (United States)

    ... before being swallowed; do not swallow them whole. Drink a full glass of water after taking either the regular or chewable tablets or capsules. Some liquid forms of calcium carbonate must be shaken well before use.Do not ...

  1. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha;

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p<0.0001) or...

  2. Calcium Calculator

    Science.gov (United States)

    ... Latvia - Lebanon - Libya - Lithuania - Luxembourg - Macedonia, Republic of - Malaysia - Malta - Mexico - Moldova - Morocco - Netherlands - New Zealand - Nigeria - ... and Statistics Popular content Calcium content of common foods What is Osteoporosis? The Board Introduction to Bone ...

  3. Stability analysis for complexes in calcium-alkali bromide solutions

    International Nuclear Information System (INIS)

    We discuss the dependence of the stability of tetrahedral complexes in molten halide mixtures on the halogen species. This is done by calculating the equilibrium concentration of (CaBr4)2- complexes in calcium-alkali bromide solutions as a function of composition, in comparison with earlier calculations on the calcium-alkali chloride systems. The comparison supports a possible trend of increasing stability from chlorides to bromides, provided that halogen polarizability or chemical bonding contribute appreciably to the binding of a complex. Supporting evidence is noted and further experiments are suggested. (author). 10 refs, 2 figs

  4. Finding New Perovskite Halides via Machine learning

    Directory of Open Access Journals (Sweden)

    Ghanshyam ePilania

    2016-04-01

    Full Text Available Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning via building a support vector machine (SVM based classifier that uses elemental features (or descriptors to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  5. Finding New Perovskite Halides via Machine learning

    Science.gov (United States)

    Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho; Lookman, Turab

    2016-04-01

    Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning) via building a support vector machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  6. Observation of color center peaks in calcium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, T. [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704, USA (United States); Garvie, L.A.J. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Rez, P., E-mail: Peter.Rez@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

    2015-06-15

    Alkali halides such as calcium fluoride all have color center defects that absorb light in the visible region. Using a moncochromator equipped, aberration corrected, scanning transmission electron microscope (STEM) we recorded spectra showing the time evolution of the generation of F and H centers in calcium fluoride. The final stage of electron beam irradiation is the formation of metallic calcium nanoparticles. High resolution low loss spectra for the Vacuum Ultraviolet region were also recorded. - Highlights: • Color center defects clearly identified by high resolution EELS of CaF{sub 2}. • Both F Centers and H Centers produced by electron beam irradiation. • Ultimately metallic calcium is left as evidenced by plasmon and density of states. • High resolution low loss (VUV) spectra also recorded.

  7. Observation of color center peaks in calcium fluoride

    International Nuclear Information System (INIS)

    Alkali halides such as calcium fluoride all have color center defects that absorb light in the visible region. Using a moncochromator equipped, aberration corrected, scanning transmission electron microscope (STEM) we recorded spectra showing the time evolution of the generation of F and H centers in calcium fluoride. The final stage of electron beam irradiation is the formation of metallic calcium nanoparticles. High resolution low loss spectra for the Vacuum Ultraviolet region were also recorded. - Highlights: • Color center defects clearly identified by high resolution EELS of CaF2. • Both F Centers and H Centers produced by electron beam irradiation. • Ultimately metallic calcium is left as evidenced by plasmon and density of states. • High resolution low loss (VUV) spectra also recorded

  8. Calcium pyrophosphate arthritis

    Science.gov (United States)

    Calcium pyrophosphate dihydrate deposition disease; CPPD disease; Acute CPPD arthritis; Pseudogout ... Calcium pyrophosphate arthritis is caused by the collection of salt called calcium pyrophosphate dihydrate (CPPD). The buildup ...

  9. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  10. Halide-Substituted Electronic Properties of Organometal Halide Perovskite Films: Direct and Inverse Photoemission Studies.

    Science.gov (United States)

    Li, Chi; Wei, Jian; Sato, Mikio; Koike, Harunobu; Xie, Zhong-Zhi; Li, Yan-Qing; Kanai, Kaname; Kera, Satoshi; Ueno, Nobuo; Tang, Jian-Xin

    2016-05-11

    Solution-processed perovskite solar cells are attracting increasing interest due to their potential in next-generation hybrid photovoltaic devices. Despite the morphological control over the perovskite films, quantitative information on electronic structures and interface energetics is of paramount importance to the optimal photovoltaic performance. Here, direct and inverse photoemission spectroscopies are used to determine the electronic structures and chemical compositions of various methylammonium lead halide perovskite films (MAPbX3, X = Cl, Br, and I), revealing the strong influence of halide substitution on the electronic properties of perovskite films. Precise control over halide compositions in MAPbX3 films causes the manipulation of the electronic properties, with a qualitatively blue shift along the I → Br → Cl series and showing the increase in ionization potentials from 5.96 to 7.04 eV and the change of transport band gaps in the range from 1.70 to 3.09 eV. The resulting light absorption of MAPbX3 films can cover the entire visible region from 420 to 800 nm. The results presented here provide a quantitative guide for the analysis of perovskite-based solar cell performance and the selection of optimal carrier-extraction materials for photogenerated electrons and holes. PMID:27101940

  11. Incidental Polymorphism, Non-Isomorphic and Isomorphic Substitution in Calcium-Valine Coordination Polymers

    Directory of Open Access Journals (Sweden)

    Kevin Lamberts

    2015-05-01

    Full Text Available Five coordination polymers with the stoichiometry CaX2(valine2(H2O2 (X = Cl, Br were obtained from the corresponding calcium halides and either racemic and enantiopure valine. In all cases the zwitterionic amino acid is exclusively O coordinated and the halides act as counteranions for the resulting one-dimensional cationic chains. The enantiopure chloride shows dimorphism; both forms differ in connectivity from the bromide. In contrast to this structural variability for L-valine, the derivatives of the racemic amino acid are isomorphous.

  12. Radiative properties of ceramic metal-halide high intensity discharge lamps containing additives in argon plasma

    Science.gov (United States)

    Cressault, Yann; Teulet, Philippe; Zissis, Georges

    2016-07-01

    The lighting represents a consumption of about 19% of the world electricity production. We are thus searching new effective and environment-friendlier light sources. The ceramic metal-halide high intensity lamps (C-MHL) are one of the options for illuminating very high area. The new C-MHL lamps contain additives species that reduce mercury inside and lead to a richer spectrum in specific spectral intervals, a better colour temperature or colour rendering index. This work is particularly focused on the power radiated by these lamps, estimated using the net emission coefficient, and depending on several additives (calcium, sodium, tungsten, dysprosium, and thallium or strontium iodides). The results show the strong influence of the additives on the power radiated despite of their small quantity in the mixtures and the increase of visible radiation portion in presence of dysprosium.

  13. Metal halide perovskites for energy applications

    Science.gov (United States)

    Zhang, Wei; Eperon, Giles E.; Snaith, Henry J.

    2016-06-01

    Exploring prospective materials for energy production and storage is one of the biggest challenges of this century. Solar energy is one of the most important renewable energy resources, due to its wide availability and low environmental impact. Metal halide perovskites have emerged as a class of semiconductor materials with unique properties, including tunable bandgap, high absorption coefficient, broad absorption spectrum, high charge carrier mobility and long charge diffusion lengths, which enable a broad range of photovoltaic and optoelectronic applications. Since the first embodiment of perovskite solar cells showing a power conversion efficiency of 3.8%, the device performance has been boosted up to a certified 22.1% within a few years. In this Perspective, we discuss differing forms of perovskite materials produced via various deposition procedures. We focus on their energy-related applications and discuss current challenges and possible solutions, with the aim of stimulating potential new applications.

  14. Thermoluminescence of alkali halides and its implications

    Science.gov (United States)

    Gartia, R. K.; Rey, L.; Tejkumar Singh, Th.; Basanta Singh, Th.

    2012-03-01

    Trapping levels present in some alkali halides namely NaCl, KCl, KBr, and KI are determined by deconvolution of the thermoluminescence (TL) curves. Unlike most of the studies undertaken over the last few decades, we have presented a comprehensive picture of the phenomenon of TL as an analytical technique capable of revealing the position of the trapping levels present in the materials. We show that for all practical purposes, TL can be described involving only the three key trapping parameters, namely, the activation energy (E), the frequency factor (s), and the order of kinetics (b) even for complex glow curves having a number of TL peaks. Finally, based on these, we logically infer the importance of TL in development and characterization of materials used in dosimetry, dating and scintillation.

  15. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  16. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  17. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  18. Silver-catalyzed coupling reactions of alkyl halides with indenyllithiums

    OpenAIRE

    Someya, Hidenori; Yorimitsu, Hideki; Oshima, Koichiro

    2010-01-01

    Coupling reactions of tertiary and secondary alkyl halides with indenyllithiums proceeded effectively in the presence of a catalytic amount of silver bromide to provide tertiary- and secondary-alkyl-substituted indene derivatives in good yields.

  19. Theory of the late stage of radiolysis of alkali halides

    OpenAIRE

    Dubinko, V. I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    2000-01-01

    Recent results on heavily irradiated natural and synthetic NaCl crystals give evidence for the formation of large vacancy voids, which were not addressed by the conventional Jain-Lidiard model of radiation damage ill alkali halides. This model was constructed to describe metal colloids and dislocation loops formed in alkali halides during earlier stages of irradiation. We present a theory based on a new mechanism of dislocation climb, which involves the production of Vt centers (self-trapped ...

  20. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture, exhausti

  1. Color silver halide hologram production and mastering

    Science.gov (United States)

    Bjelkhagen, Hans I.; Huang, Qiang

    1997-04-01

    Color reflection holograms recorded with the Denisyuk geometry have been demonstrated by the recently formed HOLOS Corporation in New Hampshire. The Slavich red-green-blue (RGB) sensitized ultra-high resolution silver halide emulsion was used for the hologram recording. The employed laser wavelengths were 647 nm, 532 nm, and 476 nm, generated by an argon ion, a frequency doubled Nd:YAG, and a krypton ion laser, respectively. A beam combination mechanism with dichroic filters enabled a simultaneous RGB exposure, which made the color balance and overall exposure energy easy to control as well as simplifying the recording procedure. HOLOS has been producing limited edition color holograms in various sizes from 4' X 5' to 12' X 16'. A 30 foot long optical table and high power lasers will enable HOLOS to record color holograms up to the size of one meter square in the near future. Various approaches have been investigated in generating color hologram masters which have sufficiently high diffraction efficiency to contact copy the color images onto photopolymer materials. A specially designed test object including the 1931 CIE chromaticity diagram, a rainbow ribbon cable, pure yellow dots, and a cloisonne elephant was used for color recording experiments. In addition, the Macbeth Color Checker chart was used. Both colorimetric evaluation and scattering noise measurements were performed using the PR-650 Photo Research SpectraScan SpectraCalorimeter.

  2. Vitrification of IFR and MSBR halide salt reprocessing wastes

    International Nuclear Information System (INIS)

    Both of the genuinely sustainable (breeder) nuclear fuel cycles (IFR - Integral Fast Reactor - and MSBR - Molten Salt Breeder Reactor -) studied by the USA's national laboratories would generate high level reprocessing waste (HLRW) streams consisting of a relatively small amount ( about 4 mole %) of fission product halide (chloride or fluoride) salts in a matrix comprised primarily (about 95 mole %) of non radioactive alkali metal halide salts. Because leach resistant glasses cannot accommodate much of any of the halides, most of the treatment scenarios previously envisioned for such HLRW have assumed a monolithic waste form comprised of a synthetic analog of an insoluble crystalline halide mineral. In practice, this translates to making a 'substituted' sodalite ('Ceramic Waste Form') of the IFR's chloride salt-based wastes and fluoroapatite of the MSBR's fluoride salt-based wastes. This paper discusses my experimental studies of an alternative waste management scenario for both fuel cycles that would separate/recycle the waste's halide and immobilize everything else in iron phosphate (Fe-P) glass. It will describe both how the work was done and what its results indicate about how a treatment process for both of those wastes should be implemented (fluoride and chloride behave differently). In either case, this scenario's primary advantages include much higher waste loadings, much lower overall cost, and the generation of a product (glass) that is more consistent with current waste management practices. (author)

  3. Halide Perovskites: Poor Man's High-Performance Semiconductors.

    Science.gov (United States)

    Stoumpos, Constantinos C; Kanatzidis, Mercouri G

    2016-07-01

    Halide perovskites are a rapidly developing class of medium-bandgap semiconductors which, to date, have been popularized on account of their remarkable success in solid-state heterojunction solar cells raising the photovoltaic efficiency to 20% within the last 5 years. As the physical properties of the materials are being explored, it is becoming apparent that the photovoltaic performance of the halide perovskites is just but one aspect of the wealth of opportunities that these compounds offer as high-performance semiconductors. From unique optical and electrical properties stemming from their characteristic electronic structure to highly efficient real-life technological applications, halide perovskites constitute a brand new class of materials with exotic properties awaiting discovery. The nature of halide perovskites from the materials' viewpoint is discussed here, enlisting the most important classes of the compounds and describing their most exciting properties. The topics covered focus on the optical and electrical properties highlighting some of the milestone achievements reported to date but also addressing controversies in the vastly expanding halide perovskite literature. PMID:27174223

  4. Two Dimensional Organometal Halide Perovskite Nanorods with Tunable Optical Properties.

    Science.gov (United States)

    Aharon, Sigalit; Etgar, Lioz

    2016-05-11

    Organo-metal halide perovskite is an efficient light harvester in photovoltaic solar cells. Organometal halide perovskite is used mainly in its "bulk" form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this paper, we present facile low-temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g., octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. The 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light-emitting diodes, lasing, solar cells, and sensors. PMID:27089497

  5. Process for oxidation of hydrogen halides to elemental halogens

    Science.gov (United States)

    Lyke, Stephen E.

    1992-01-01

    An improved process for generating an elemental halogen selected from chlorine, bromine or iodine, from a corresponding hydrogen halide by absorbing a molten salt mixture, which includes sulfur, alkali metals and oxygen with a sulfur to metal molar ratio between 0.9 and 1.1 and includes a dissolved oxygen compound capable of reacting with hydrogen halide to produce elemental halogen, into a porous, relatively inert substrate to produce a substrate-supported salt mixture. Thereafter, the substrate-supported salt mixture is contacted (stage 1) with a hydrogen halide while maintaining the substrate-supported salt mixture during the contacting at an elevated temperature sufficient to sustain a reaction between the oxygen compound and the hydrogen halide to produce a gaseous elemental halogen product. This is followed by purging the substrate-supported salt mixture with steam (stage 2) thereby recovering any unreacted hydrogen halide and additional elemental halogen for recycle to stage 1. The dissolved oxygen compound is regenerated in a high temperature (stage 3) and an optical intermediate temperature stage (stage 4) by contacting the substrate-supported salt mixture with a gas containing oxygen whereby the dissolved oxygen compound in the substrate-supported salt mixture is regenerated by being oxidized to a higher valence state.

  6. High Biomass Specific Methyl Halide Production Rates of Selected Coastal Marsh Plants and its Relationship to Halide Content

    Science.gov (United States)

    Manley, S. L.; Wang, N.; Cicerone, R. J.

    2002-12-01

    Salt tolerant coastal marsh plants (halophytes) have previously been shown to be globally significant producers of methyl chloride (MeCl) and methyl bromide (MeBr). While halophytes are known for their high salt content, there are few reports of their halide content. Our studies have attempted to quantify biomass specific methyl halide (MeX) production from these plants and relate it to tissue halide levels. MeCl, MeBr and MeI production rates and tissue chloride, bromide and iodide concentrations from selected coastal marsh plants were measured for nearly a year. Certain halophyte species (i.e. Batis and Frankenia) have very high summer biomass specific production rates for MeX (e.g. Frankenia: 1 ug MeCl /gfwt/hr; 80 ng MeBr/gfwt/hr; 8 ng MeI/gfwt/hr). These rates of MeCl and MeBr production are much higher than those from other coastal marsh plants or seaweeds. Plant halide levels remain high throughout the year, while MeX production peaks at a high level in mid summer falling to low winter rates. This implies a linkage to plant growth. Higher levels of chloride and bromide were seen in the fleshy marsh plants such as Batis (saltwort, approximately 20 percent dry wt chloride, 0.4 percent dry wt bromide) and Salicornia (pickleweed) than in the others such as Frankenia (alkali heath) approx 7 percent dry wt chloride, 0.1 percent dry wt bromide) or Spartina (cordgrass). No such trend was seen for iodide, which ranged from 4 - 10 ppm. Calculations show the daily halide losses from MeX production are far less than the variability in tissue halide content. MeX production removes a small fraction of the total tissue halide from these plants suggesting that MeX production is not a mechanism used by these species to control internal halide levels. Saltwort cell-free extracts incubated with bromide or iodide in the presence of S-adenosyl-L-methionine (SAM) produced the corresponding MeX. MeBr production was inhibited by caffeic acid the substrate of lignin-specific O

  7. Solvated Positron Chemistry. Competitive Positron Reactions with Halide Ions in Water

    DEFF Research Database (Denmark)

    Christensen, Palle; Pedersen, Niels Jørgen; Andersen, J. R.;

    1979-01-01

    It is shown by means of the angular correlation technique that the binding of positrons to halides is strongly influenced by solvation effects. For aqueous solutions we find increasing values for the binding energies between the halide and the positron with increasing mass of the halide. This is...

  8. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  9. Coronary Calcium Scan

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  10. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  11. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  12. Calcium in diet

    Science.gov (United States)

    Diet - calcium ... Calcium is one of the most important minerals for the human body. It helps form and maintain healthy teeth and bones. A proper level of calcium in the body over a lifetime can help ...

  13. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  14. Halide-Dependent Electronic Structure of Organolead Perovskite Materials

    KAUST Repository

    Buin, Andrei

    2015-06-23

    © 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention both at the experimental and theoretical levels. These materials, in particular methylammonium triiodide, are still limited by poor chemical and structural stability under ambient conditions. Today this represents one of the major challenges for polycrystalline perovskite-based photovoltaic technology. In addition to this, the performance of perovskite-based devices is degraded by deep localized states, or traps. To achieve better-performing devices, it is necessary to understand the nature of these states and the mechanisms that lead to their formation. Here we show that the major sources of deep traps in the different halide systems have different origin and character. Halide vacancies are shallow donors in I-based perovskites, whereas they evolve into a major source of traps in Cl-based perovskites. Lead interstitials, which can form lead dimers, are the dominant source of defects in Br-based perovskites, in line with recent experimental data. As a result, the optimal growth conditions are also different for the distinct halide perovskites: growth should be halide-rich for Br and Cl, and halide-poor for I-based perovskites. We discuss stability in relation to the reaction enthalpies of mixtures of bulk precursors with respect to final perovskite product. Methylammonium lead triiodide is characterized by the lowest reaction enthalpy, explaining its low stability. At the opposite end, the highest stability was found for the methylammonium lead trichloride, also consistent with our experimental findings which show no observable structural variations over an extended period of time.

  15. Ultrafast time-resolved spectroscopy of lead halide perovskite films

    Science.gov (United States)

    Idowu, Mopelola A.; Yau, Sung H.; Varnavski, Oleg; Goodson, Theodore

    2015-09-01

    Recently, lead halide perovskites which are organic-inorganic hybrid structures, have been discovered to be highly efficient as light absorbers. Herein, we show the investigation of the excited state dynamics and emission properties of non-stoichiometric precursor formed lead halide perovskites grown by interdiffusion method using steady-state and time-resolved spectroscopic measurements. The influence of the different ratios of the non-stoichiometric precursor solution was examined. The observed photoluminescence properties were correlated with the femtosecond transient absorption measurements.

  16. Thallous and cesium halide materials for use in cryogenic applications

    International Nuclear Information System (INIS)

    Certain thallous and cesium halides, either used alone or in combination with other ceramic materials, are provided in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires, and as dielectric insulating materials. The thallous and cesium halides possess unusually large specific heats at low temperatures, have large thermal conductivities, are nonmagnetic, and are nonconductors of electricity. They can be formed into a variety of shapes such as spheres, bars, rods, or the like and can be coated or extruded onto substrates or wires. (author)

  17. Semiempirical and DFT Investigations of the Dissociation of Alkyl Halides

    Science.gov (United States)

    Waas, Jack R.

    2006-01-01

    Enthalpy changes corresponding to the gas phase heats of dissociation of 12 organic halides were calculated using two semiempirical methods, the Hartree-Fock method, and two DFT methods. These calculated values were compared to experimental values where possible. All five methods agreed generally with the expected empirically known trends in the…

  18. Kinetic Studies of the Solvolysis of Two Organic Halides

    Science.gov (United States)

    Duncan, J. A.; Pasto, D. J.

    1975-01-01

    Describes an undergraduate organic chemistry laboratory experiment which utilizes the solvolysis of organic halides to demonstrate first and second order reaction kinetics. The experiment also investigates the effect of a change of solvent polarity on reaction rate, common-ion and noncommon-ion salt effects, and the activation parameters of a…

  19. On the Boiling Points of the Alkyl Halides.

    Science.gov (United States)

    Correia, John

    1988-01-01

    Discusses the variety of explanations in organic chemistry textbooks of a physical property of organic compounds. Focuses on those concepts explaining attractive forces between molecules. Concludes that induction interactions play a major role in alkyl halides and other polar organic molecules and should be given wider exposure in chemistry texts.…

  20. A new mechanism for radiation damage processes in alkali halides

    NARCIS (Netherlands)

    Dubinko, V.I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    1999-01-01

    We present a theory of radiation damage formation in alkali halides based on a new mechanism of dislocation climb, which involves the production of VF centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of H centers of dislocation lines. We consider the evolution o

  1. Halide glass containing trivalent uranium ions and its fabrication process

    International Nuclear Information System (INIS)

    This halide glass, showing an optical attenuation -1 in the near infrared from 2.2 to 304 micrometers, is prepared with a glass containing uranium ions as U4+ and/or U5+ reduced by ionizing radiations in U3+. Application is made to the fabrication of optical fibers and lasers doped with trivalent uranium

  2. Theory of the late stage of radiolysis of alkali halides

    NARCIS (Netherlands)

    Dubinko, V.I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    2000-01-01

    Recent results on heavily irradiated natural and synthetic NaCl crystals give evidence for the formation of large vacancy voids, which were not addressed by the conventional Jain-Lidiard model of radiation damage ill alkali halides. This model was constructed to describe metal colloids and dislocati

  3. Students' Understanding of Alkyl Halide Reactions in Undergraduate Organic Chemistry

    Science.gov (United States)

    Cruz-Ramirez de Arellano, Daniel

    2013-01-01

    Organic chemistry is an essential subject for many undergraduate students completing degrees in science, engineering, and pre-professional programs. However, students often struggle with the concepts and skills required to successfully solve organic chemistry exercises. Since alkyl halides are traditionally the first functional group that is…

  4. Calcium and Vitamin D

    Science.gov (United States)

    ... Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is essential ... counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D plays ...

  5. Importance of Calcium

    OpenAIRE

    TANDOĞAN, Berivan; ULUSU, N. Nuray

    2005-01-01

    Calcium is the most abundant mineral in the body. Calcium regulates many cellular processes and has important structural roles in living organisms. Skeletal muscle structure and function, polymerisation of fibrin and the conduction of impulses in the nervous system are regulated by calcium. Calcium is an important intracellular messenger in protozoa, plants, and animals. Calcium-transporting systems which are located in the plasma membrane and in the organelles, regulate the ionic concentrati...

  6. Low-temperature luminescent properties of Mn-activated layered cadmium and calcium halides

    International Nuclear Information System (INIS)

    Luminescent properties of CdCl2, CdBr2, CdI2, and CaI2 crystals activated by manganese are investigated at 4.2-200 K. Activator bands in the red spectrum region are detected in spectra of crystal luminescence. Spectra of excitation and kinetics of activator luminescence are considered in the framework of crystal field theory taking into account results of electron spin resonance spectra investigations. It is concluded that impurity crystal luminescence in red spectrum region at 4.2 K is caused by electron-phonon transitions in Mn2+ ions

  7. Matrix isolation infrared spectra of hydrogen halide and halogen complexes with nitrosyl halides

    Science.gov (United States)

    Allamandola, Louis J.; Lucas, Donald; Pimentel, George C.

    1982-01-01

    Matrix isolation infrared spectra of nitrosyl halide (XNO) complexes with HX and X2 (X = Cl, Br) are presented. The relative frequency shifts of the HX mode are modest (ClNO H-Cl, delta-nu/nu = -0.045; BrNO H-Br, delta-nu/nu = -0.026), indicating weak hydrogen bonds 1-3 kcal/mol. These shifts are accompanied by significant shifts to higher frequencies in the XN-O stretching mode (CIN-O HCl, delta-nu/nu = +0.016; BrN-O HBr, delta-nu/nu = +0.011). Similar shifts were observed for the XN-O X2 complexes (ClN-O Cl2, delta-nu/nu = +0.009; BrN-O-Br2, delta-nu/nu = +0.013). In all four complexes, the X-NO stretching mode relative shift is opposite in sign and about 1.6 times that of the NO stretching mode. These four complexes are considered to be similar in structure and charge distribution. The XN-O frequency shift suggests that complex formation is accompanied by charge withdrawal from the NO bond ranging from about .04 to .07 electron charges. The HX and X2 molecules act as electron acceptors, drawing electrons out of the antibonding orbital of NO and strengthening the XN-O bond. The implications of the pattern of vibrational shifts concerning the structure of the complexes are discussed.

  8. Electrolytic systems and methods for making metal halides and refining metals

    Science.gov (United States)

    Holland, Justin M.; Cecala, David M.

    2015-05-26

    Disclosed are electrochemical cells and methods for producing a halide of a non-alkali metal and for electrorefining the halide. The systems typically involve an electrochemical cell having a cathode structure configured for dissolving a hydrogen halide that forms the halide into a molten salt of the halogen and an alkali metal. Typically a direct current voltage is applied across the cathode and an anode that is fabricated with the non-alkali metal such that the halide of the non-alkali metal is formed adjacent the anode. Electrorefining cells and methods involve applying a direct current voltage across the anode where the halide of the non-alkali metal is formed and the cathode where the non-alkali metal is electro-deposited. In a representative embodiment the halogen is chlorine, the alkali metal is lithium and the non-alkali metal is uranium.

  9. Large methyl halide emissions from south Texas salt marshes

    Directory of Open Access Journals (Sweden)

    R. C. Rhew

    2014-06-01

    Full Text Available Coastal salt marshes are natural sources of methyl chloride (CH3Cl and methyl bromide (CH3Br to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.

  10. Alkali Halide Microstructured Optical Fiber for X-Ray Detection

    Science.gov (United States)

    DeHaven, S. L.; Wincheski, R. A.; Albin, S.

    2014-01-01

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  11. Facile Preparation of Silver Halide Nanoparticles as Visible Light Photocatalysts

    Directory of Open Access Journals (Sweden)

    Linfan Cui

    2015-07-01

    Full Text Available In this study, highly efficient silver halide (AgX-based photocatalysts were successfully fabricated using a facile and template-free direct-precipitation method. AgX nanoparticles, which included silver chloride (AgCl, silver bromide (AgBr and silver iodide (AgI, were synthesized using different potassium halides and silver acetate as reactive sources. The size distribution of the AgX nanopar‐ ticles was determined by the reaction time and ratio of the reagents, which were monitored by UV-vis spectra. The as- prepared AgX nanoparticles exhibited different photoca‐ talytic properties. This shows the differences for the photodegradation of methyl orange and Congo red dyes. In addition, the AgCl nanoparticle-based photocatalyst exhibited the best photocatalytic property among all three types of AgX nanoparticles that are discussed in this study. Therefore, it is a good candidate for removing organic pollutants.

  12. Correlations between entropy and volume of melting in halide salts

    International Nuclear Information System (INIS)

    Melting parameters and transport coefficients in the melt are collated for halides of monovalent, divalent and trivalent metals. A number of systems show a deficit of entropy of melting relative to the linear relationships between entropy change and relative volume change on melting that are found to be approximately obeyed by a majority of halides. These behaviours are discussed on the basis of structural and transport data. The deviating systems are classified into three main classes, namely (i) fast-ion conductors in the high-temperature crystal phase such as AgI, (ii) strongly structured network-like systems such as ZnCl2, and (iii) molecular systems melting into associated molecular liquids such as SbCl3. (author). 35 refs, 1 fig., 3 tabs

  13. Stability diagrams for complexes in molten mixtures of halide salts

    International Nuclear Information System (INIS)

    The stability of local fourfold coordination for divalent and trivalent metal ions in liquid mixtures of polyvalent metal halides and alkali halides is classified by means of structural coordinates obtained from properties of the elements. In parallel with earlier classifications of compound crystal structures and molecular shapes, the elemental properties are taken from first-principles calculations of valence electron orbitals in atoms, in the form of (i) the nodal radii of Andreoni, Baldereschi and Guizzetti or (ii) the pseudo-potential radii of Zunger and Cohen. As a third alternative we also consider a classification based on Pettifor's phenomenological chemical scale of the elements. The alternative structural classification schemes that are developed from these elemental properties are very successful in distinguishing molten mixtures in which the available experimental evidence indicates stability of ''complexes'', i.e. long-lived fourfold coordination of polyvalent metal ions. (author). 55 refs, 3 figs

  14. Alkali halide microstructured optical fiber for X-ray detection

    International Nuclear Information System (INIS)

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed

  15. Oxidative alkoxylation of phosphine in alcohol solutions of copper halides

    Science.gov (United States)

    Polimbetova, G. S.; Borangazieva, A. K.; Ibraimova, Zh. U.; Bugubaeva, G. O.; Keynbay, S.

    2016-08-01

    The phosphine oxidation reaction with oxygen in alcohol solutions of copper (I, II) halides is studied. Kinetic parameters, intermediates, and by-products are studied by means of NMR 31Р-, IR-, UV-, and ESR- spectroscopy; and by magnetic susceptibility, redox potentiometry, gas chromatography, and elemental analysis. A reaction mechanism is proposed, and the optimum conditions are found for the reaction of oxidative alkoxylation phosphine.

  16. Study of methyl halide fluxes in temperate and tropical ecosystems

    OpenAIRE

    Blei, Emanuel

    2010-01-01

    CH3Br and CH3Cl (methyl halides) are the most abundant natural vectors of bromine and chlorine into the stratosphere and play an important role in stratospheric ozone destruction. The current knowledge of their respective natural sources is incomplete leading to large uncertainties in their global budgets. Beside the issue of quantification, characterisation of possible sources is needed to assist modelling of future environmental change impacts on these sources and hence the s...

  17. Influence of the Print Run on Silver Halide Printing Plates

    Directory of Open Access Journals (Sweden)

    Tomislav Cigula

    2010-09-01

    Full Text Available The most common printing technique today is lithography. The difference between printing and nonprinting areason a printing plate is accomplished by opposite physical and chemical properties of those areas (MacPhee, 1998.The printing areas are made of photoactive layer that attracts oil and chemical substances with oil solvent – printinginks. The nonprinting areas are made of aluminium-oxide which attracts water based substances – the fountainsolution.There are many of various types of photoactive layer which are used for production of offset printing plates, amongothers is silver halide layer. The usage of the silver halide technology in the graphic reproduction is not a novelty.The filmmaking phase is based on the usage of the silver halide as the photographically active ingredient, for instance,AgBr (silver bromide. The new, digital plate making technology (Computer to Plate, CtP eliminates thefilmmaking phase and therefore enables control of the printing plate’s exposure made by computer. CtP technologyeliminates the filmmaking phase, but it also results with the reduction of needed material quantities and requiredtime for the production (Limburg, 1994; Seydel, 1996.In this paper the basis of the graphic reproduction by using the silver halide digital printing plates was described.The changes of the AgX copying layer and the surface of the aluminium base in the printing process have beenobserved. The surface characteristics were determined by measuring the relevant surface roughness parameters. Inaddition, measurements of coverage values on the prints, detailed at smaller print run, were conducted.Results showed that surface changes on the printing plate are changing during printing process and that thesechanges influence transfer of the printing ink on the printing substrate. These measurements proved to be of greatinterest in the graphic reproduction as they enable us to determine consistency of the printing plates during theprinting

  18. Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

    Science.gov (United States)

    Shrestha, Bijay

    2015-01-01

    Summary We report a Cu-catalyzed coupling between triarylaluminum reagents and alkyl halides to form arylalkanes. The reaction proceeds in the presence of N,N,N’,N’-tetramethyl-o-phenylenediamine (NN-1) as a ligand in combination with CuI as a catalyst. This catalyst system enables the coupling of primary alkyl iodides and bromides with electron-neutral and electron-rich triarylaluminum reagents and affords the cross-coupled products in good to excellent yields. PMID:26734088

  19. Semiphysical development of holograms recorded in silver halide emulsions

    Science.gov (United States)

    Banyasz, Istvan; Belendez, Augusto; Pascual, Inmaculada V.; Fimia, Antonio

    2000-10-01

    In the course of experiments on measurement of the effects of processing on nonlinear characteristics of silver halide holograms recorded in Agfa-gevaert 8E75HD emulsions we found that, under certain circumstances, the AAC developer acted as a semi-physical developer instead of the normal chemical developing action. The developed and fixed holograms were of low optical density (carbonate of purest grade with that of for analysis grade of the same company.

  20. Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

    Directory of Open Access Journals (Sweden)

    Bijay Shrestha

    2015-12-01

    Full Text Available We report a Cu-catalyzed coupling between triarylaluminum reagents and alkyl halides to form arylalkanes. The reaction proceeds in the presence of N,N,N’,N’-tetramethyl-o-phenylenediamine (NN-1 as a ligand in combination with CuI as a catalyst. This catalyst system enables the coupling of primary alkyl iodides and bromides with electron-neutral and electron-rich triarylaluminum reagents and affords the cross-coupled products in good to excellent yields.

  1. Calcium in diet

    Science.gov (United States)

    ... best source. Milk and dairy products such as yogurt, cheeses, and buttermilk contain a form of calcium ... the amount of calcium in a dairy product. Yogurt, most cheeses, and buttermilk are excellent sources of ...

  2. Fenoprofen calcium overdose

    Science.gov (United States)

    Fenoprofen calcium is a type of medicine called a nonsteroidal anti-inflammatory drug. It is a prescription pain medicine used to relieve symptoms of arthritis . Fenoprofen calcium overdose occurs when someone takes more than the ...

  3. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium channel blockers are a type of medicine used ...

  4. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  5. Effects of Halides on Plasmid-Mediated Silver Resistance in Escherichia coli

    OpenAIRE

    Gupta, Amit; Maynes, Maria; Silver, Simon

    1998-01-01

    Silver resistance of sensitive Escherichia coli J53 and resistance plasmid-containing J53(pMG101) was affected by halides in the growth medium. The effects of halides on Ag+ resistance were measured with AgNO3 and silver sulfadiazine, both on agar and in liquid. Low concentrations of chloride made the differences in MICs between sensitive and resistant strains larger. High concentrations of halides increased the sensitivities of both strains to Ag+.

  6. Methods and Mechanisms for Cross-Electrophile Coupling of Csp2 Halides with Alkyl Electrophiles

    OpenAIRE

    Weix, Daniel J.

    2015-01-01

    Conspectus Cross-electrophile coupling, the cross-coupling of two different electrophiles, avoids the need for preformed carbon nucleophiles, but development of general methods has lagged behind cross-coupling and C–H functionalization. A central reason for this slow development is the challenge of selectively coupling two substrates that are alike in reactivity. This Account describes the discovery of generally cross-selective reactions of aryl halides and acyl halides with alkyl halides, th...

  7. Lamp-Ballast Compatibility Index for Efficient Ceramic Metal Halide Lamp Operation

    OpenAIRE

    Sourish Chatterjee

    2013-01-01

    Development of energy efficient products and exploration of energy saving potential are major challenges for present day’s technology. Ceramic Metal Halide lamp is the latest improved version of metal halide lamp that finds its wide applications in indoor commercial lighting especially in retail shop lighting. This lamp shows better performance in terms of higher lumen per watt and colour constancy in comparison to conventional metal halide lamp. The inherent negative incremental impedance of...

  8. Environmental controls over methyl halide emissions from rice paddies

    Science.gov (United States)

    Redeker, K. R.; Cicerone, R. J.

    2004-03-01

    This paper examines primary controlling factors that affect methyl halide emissions from rice paddy ecosystems. Observations of four cultivars under multiple growth conditions during studies in commercial fields and the University of California, Irvine, greenhouse lead to the conclusion that daily emissions of methyl halides are primarily determined by the growth stage of the rice plant, with the exception that methyl chloride emissions show no clear seasonal pattern. Methyl chloride emissions appear to be more from the paddy water and/or soil as opposed to the plants; however, in soils with high chloride content, these emissions appear to peak during the reproductive phase. Strong secondary influences include air temperature, soil halide concentration, and soil pore water saturation. The cultivars studied had statistically separate seasonally integrated emissions. Irradiant light and aboveground biomass appear to have little effect on emissions. Emissions of methyl chloride, methyl bromide, and methyl iodide are estimated to be 3.5, 2.3, and 48 mg/m2/yr, or 5.3, 3.5, and 72 Gg/yr, from rice paddies globally.

  9. Quantum Size Effect in Organometal Halide Perovskite Nanoplatelets.

    Science.gov (United States)

    Sichert, Jasmina A; Tong, Yu; Mutz, Niklas; Vollmer, Mathias; Fischer, Stefan; Milowska, Karolina Z; García Cortadella, Ramon; Nickel, Bert; Cardenas-Daw, Carlos; Stolarczyk, Jacek K; Urban, Alexander S; Feldmann, Jochen

    2015-10-14

    Organometal halide perovskites have recently emerged displaying a huge potential for not only photovoltaic, but also light emitting applications. Exploiting the optical properties of specifically tailored perovskite nanocrystals could greatly enhance the efficiency and functionality of applications based on this material. In this study, we investigate the quantum size effect in colloidal organometal halide perovskite nanoplatelets. By tuning the ratio of the organic cations used, we can control the thickness and consequently the photoluminescence emission of the platelets. Quantum mechanical calculations match well with the experimental values. We find that not only do the properties of the perovskite, but also those of the organic ligands play an important role. Stacking of nanoplatelets leads to the formation of minibands, further shifting the bandgap energies. In addition, we find a large exciton binding energy of up to several hundreds of meV for nanoplatelets thinner than three unit cells, partially counteracting the blueshift induced by quantum confinement. Understanding of the quantum size effects in perovskite nanoplatelets and the ability to tune them provide an additional method with which to manipulate the optical properties of organometal halide perovskites. PMID:26327242

  10. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth.

    Science.gov (United States)

    Yang, Bin; Keum, Jong; Ovchinnikova, Olga S; Belianinov, Alex; Chen, Shiyou; Du, Mao-Hua; Ivanov, Ilia N; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2016-04-20

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films, a major unresolved question is the competition between multiple halide species (e.g., I(-), Cl(-), Br(-)) in the formation of the mixed-halide perovskite crystals. Whether Cl(-) ions are successfully incorporated into the perovskite crystal structure or, alternatively, where they are located is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br(-) or Cl(-) ions can promote crystal growth, yet reactive I(-) ions prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl(-) ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performing and cost-effective optoelectronic devices. PMID:26931634

  11. Calcium and magnesium disorders.

    Science.gov (United States)

    Goff, Jesse P

    2014-07-01

    Hypocalcemia is a clinical disorder that can be life threatening to the cow (milk fever) and predisposes the animal to various other metabolic and infectious disorders. Calcium homeostasis is mediated primarily by parathyroid hormone, which stimulates bone calcium resorption and renal calcium reabsorption. Parathyroid hormone stimulates the production of 1,25-dihydroxyvitamin D to enhance diet calcium absorption. High dietary cation-anion difference interferes with tissue sensitivity to parathyroid hormone. Hypomagnesemia reduces tissue response to parathyroid hormone. PMID:24980727

  12. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  13. Systematic analysis of the unique band gap modulation of mixed halide perovskites.

    Science.gov (United States)

    Kim, Jongseob; Lee, Sung-Hoon; Chung, Choong-Heui; Hong, Ki-Ha

    2016-02-14

    Solar cells based on organic-inorganic hybrid metal halide perovskites have been proven to be one of the most promising candidates for the next generation thin film photovoltaic cells. Mixing Br or Cl into I-based perovskites has been frequently tried to enhance the cell efficiency and stability. One of the advantages of mixed halides is the modulation of band gap by controlling the composition of the incorporated halides. However, the reported band gap transition behavior has not been resolved yet. Here a theoretical model is presented to understand the electronic structure variation of metal mixed-halide perovskites through hybrid density functional theory. Comparative calculations in this work suggest that the band gap correction including spin-orbit interaction is essential to describe the band gap changes of mixed halides. In our model, both the lattice variation and the orbital interactions between metal and halides play key roles to determine band gap changes and band alignments of mixed halides. It is also presented that the band gap of mixed halide thin films can be significantly affected by the distribution of halide composition. PMID:26791587

  14. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of cardiop

  15. Involvement of S-adenosylmethionine-dependent halide/thiol methyltransferase (HTMT) in methyl halide emissions from agricultural plants: isolation and characterization of an HTMT-coding gene from Raphanus sativus (daikon radish)

    OpenAIRE

    Taniguchi Tomokazu; Negishi Takashi; Matsuda Michiko; Toda Hiroshi; Itoh Nobuya; Ohsawa Noboru

    2009-01-01

    Abstract Background Biogenic emissions of methyl halides (CH3Cl, CH3Br and CH3I) are the major source of these compounds in the atmosphere; however, there are few reports about the halide profiles and strengths of these emissions. Halide ion methyltransferase (HMT) and halide/thiol methyltransferase (HTMT) enzymes concerning these emissions have been purified and characterized from several organisms including marine algae, fungi, and higher plants; however, the correlation between emission pr...

  16. Seasonal variations in halides in marine brown algae from Porbandar and Okha coasts (NW coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Ch.K.; Singbal, S.Y.S.

    Seasonal variation of halides and their ratios were estimated in three brown algae, namely Cystoseira indica, Sargassum tenerrimum) and S. johnstonii from Porbandar and Okha Coasts. Halides were found to be higher in early stages of growth. The Br...

  17. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  18. Artificial Synapses: Organometal Halide Perovskite Artificial Synapses (Adv. Mater. 28/2016).

    Science.gov (United States)

    Xu, Wentao; Cho, Himchan; Kim, Young-Hoon; Kim, Young-Tae; Wolf, Christoph; Park, Chan-Gyung; Lee, Tae-Woo

    2016-07-01

    A synapse-emulating electronic device based on organometal halide perovskite thin films is described by T.-W. Lee and co-workers on page 5916. The device successfully emulates important characteristics of a biological synapse. This work extends the application of organometal halide perovskites to bioinspired electronic devices, and contributes to the development of neuromorphic electronics. PMID:27442971

  19. Formal Nucleophilic Boryl Substitution of Organic Halides with Silylborane/Alkoxy Base System

    OpenAIRE

    Yamamoto, Eiji; Izumi, Kiyotaka; Horita, Yuko; Ukigai, Satoshi; Ito, Hajime

    2014-01-01

    Boryl substitution of organohalides with a silylborane and alkoxy bases is described. This reaction can be applied to various functionalized aryl halides. Alkyl and alkenyl halides, and even sterically congested aryl bromides also provided the corresponding borylated products in high yields. Mechanistic studies indicated that neither trace transition-metal impurities nor aryl radical species involved in this reaction.

  20. Temperature effects in the absorption spectra and exciton luminescence in ammonium halides

    International Nuclear Information System (INIS)

    Warm-up behavior of the first maximum exciton absorption bands in ammonium halides is explored. Under phase transition occurs offset of bands, bound both with changing a parameter of lattice, and efficient mass of exciton. Warm-up dependency of quantum leaving a luminescence of self-trapped excitons in ammonium halides is measured. (author)

  1. EXERCISE ENHANCING CALCIUM ABSORPTION MECHANISM

    OpenAIRE

    Muliani

    2013-01-01

    Calcium has important role in many biological processes therefore calcium homeostasis should be maintained. Imbalance in calcium homeostasis would affects the bone metabolism, neuromuscular function, blood coagulation, cell proliferation and signal transduction. Homeostasis of calcium is maintained by three major organs: gastrointestinal tract, bone and kidney. Intestinal calcium absorption is the sole mechanism to supply calcium to the body. Calcium absorption controlled by calcitropic hormo...

  2. Impact of the organic halide salt on final perovskite composition for photovoltaic applications

    KAUST Repository

    Moore, David T.

    2014-08-01

    The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material.Despite recent advances, however, there are still a number of fundamental aspects of their formation as well as their physical and electronic behavior that are not well understood. In this letter we explore the mechanism by which these materials crystallize by testing the outcome of each of the reagent halide salts. We find that components of both salts, lead halide and methylammonium halide, are relatively mobile and can be readily exchanged during the crystallization process when the reaction is carried out in solution or in the solid state. We exploit this fact by showing that the perovskite structure is formed even when the lead salt\\'s anion is a non-halide, leading to lower annealing temperature and time requirements for film formation. Studies into these behaviors may ultimately lead to improved processing conditions for photovoltaic films. © 2014 Author(s).

  3. Impact of the organic halide salt on final perovskite composition for photovoltaic applications

    International Nuclear Information System (INIS)

    The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material. Despite recent advances, however, there are still a number of fundamental aspects of their formation as well as their physical and electronic behavior that are not well understood. In this letter we explore the mechanism by which these materials crystallize by testing the outcome of each of the reagent halide salts. We find that components of both salts, lead halide and methylammonium halide, are relatively mobile and can be readily exchanged during the crystallization process when the reaction is carried out in solution or in the solid state. We exploit this fact by showing that the perovskite structure is formed even when the lead salt's anion is a non-halide, leading to lower annealing temperature and time requirements for film formation. Studies into these behaviors may ultimately lead to improved processing conditions for photovoltaic films

  4. Structural, dynamical, and transport properties of the hydrated halides: How do At− bulk properties compare with those of the other halides, from F− to I−?

    OpenAIRE

    Réal, Florent; Severo Pereira Gomes, Andre; Guerrero Martínez, Yansel Omar; Galland, Nicolas; Vallet, Valérie; Masella, Michel; Ayed, Tarah

    2016-01-01

    International audience The properties of halides from the lightest, uoride (F−), to the heaviest, astatide (At−), have been studied in water using a polarizable force- eld approach based on molecular dynamics (MD) simulations at the 10 ns scale. The selected force- eld explicitly treats the cooperativity within the halide-water hydrogen bond networks. The force- eld parameters have been adjusted to ab initio data on anion/water clusters computed at the relativistic Möller-Plesset second-o...

  5. Silylaryl Halides Can Replace Triflates as Aryne Precursors.

    Science.gov (United States)

    Mesgar, Milad; Daugulis, Olafs

    2016-08-01

    Silylaryl bromides and iodides can be prepared in one step from commercially available starting materials. Arynes can be generated from these compounds under conditions nearly identical to those employed for silylaryl triflates. Three distinct transformations, ortho-arylation of N-tritylanilines, intermolecular addition of arynes to amides, and reaction of ureas with arynes, were shown to be successful for the new aryne precursors. The main advantage of silylaryl halides relative to silyl aryl triflates is their one-step preparation from commercially available starting materials. PMID:27415183

  6. A new mechanism for radiation damage processes in alkali halides

    OpenAIRE

    Dubinko, V. I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    1999-01-01

    We present a theory of radiation damage formation in alkali halides based on a new mechanism of dislocation climb, which involves the production of VF centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of H centers of dislocation lines. We consider the evolution of all experimentally observed extended defects: metal colloids, gas bubbles, and vacancy voids. Voids are shown to arise and grow large due to the reaction between F and VF centers at the surface o...

  7. Thermal conductivity of halide solid solutions: measurement and prediction.

    Science.gov (United States)

    Gheribi, Aïmen E; Poncsák, Sándor; St-Pierre, Rémi; Kiss, László I; Chartrand, Patrice

    2014-09-14

    The composition dependence of the lattice thermal conductivity in NaCl-KCl solid solutions has been measured as a function of composition and temperature. Samples with systematically varied compositions were prepared and the laser flash technique was used to determine the thermal diffusivity from 373 K to 823 K. A theoretical model, based on the Debye approximation of phonon density of state (which contains no adjustable parameters) was used to predict the thermal conductivity of both stoichiometric compounds and fully disordered solid solutions. The predictions obtained with the model agree very well with our measurement. A general method for predicting the thermal conductivity of different halide systems is discussed. PMID:25217938

  8. A new mechanism for radiation damage processes in alkali halides

    Science.gov (United States)

    Dubinko, V. I.; Turkin, A. A.; Vainshtein, D. I.; den Hartog, H. W.

    1999-12-01

    We present a theory of radiation damage formation in alkali halides based on a new mechanism of dislocation climb, which involves the production of VF centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of H centers of dislocation lines. We consider the evolution of all experimentally observed extended defects: metal colloids, gas bubbles, and vacancy voids. Voids are shown to arise and grow large due to the reaction between F and VF centers at the surface of halogen bubbles. Voids can ignite a back reaction between the radiolytic products resulting in decomposition of the irradiated material.

  9. Coordination chemistry of halides and oxohalides of tungsten (6)

    International Nuclear Information System (INIS)

    Literature data on the structure of molecular complexes of halides, exo- and dioxohalides of tungsten (6), as well as results of the study of WX6, WOX4 and WO2X2 structures in gaseous phase, crystal state and in solutions of organic solvents, were generalized. The greatest volume of structural studies involved complexes W6 with oxygen-containing ligands. The presence of cis- and trans- effects of aliquotly bound oxygen atoms in complexes of exo- and dioxohalides of tungsten is pointed out

  10. RENUW - A dry halide process for nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    The RENUW Dry Halide Process for reprocessing nuclear fuel will be described. Analysis has shown that the RENUW process will significantly reduce the waste produces from processing irradiated nuclear fuel compared to aqueous processes. Waste reduction is accomplished by recovering the zirconium and uranium for reuse. The RENUW process uses hot chlorine gas to chlorinate the feed; separation is accomplished by exploiting the large differences between the relative volatilities of the fission products and the uranium and zirconium. The flow sheet is quite simple and uses readily commercial technologies

  11. RENUW - A dry halide process for nuclear fuel reprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Lahoda, E.J.; McLaughlin, D.F.; Peterson, S.H.; Burgman, H.A. [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Behrens, R. Jr.; Johnston, S.C.; Vosen, S.R. [Sandia National Laboratories, Livermore, CA (United States); Christian, J.D. [Westinghouse Idaho Nuclear Company, Idaho Falls, ID (United States)

    1993-12-31

    The RENUW Dry Halide Process for reprocessing nuclear fuel will be described. Analysis has shown that the RENUW process will significantly reduce the waste produces from processing irradiated nuclear fuel compared to aqueous processes. Waste reduction is accomplished by recovering the zirconium and uranium for reuse. The RENUW process uses hot chlorine gas to chlorinate the feed; separation is accomplished by exploiting the large differences between the relative volatilities of the fission products and the uranium and zirconium. The flow sheet is quite simple and uses readily commercial technologies.

  12. Optical Properties of Photovoltaic Organic-Inorganic Lead Halide Perovskites.

    Science.gov (United States)

    Green, Martin A; Jiang, Yajie; Soufiani, Arman Mahboubi; Ho-Baillie, Anita

    2015-12-01

    Over the last several years, organic-inorganic lead halide perovskites have rapidly emerged as a new photovoltaic contender. Although energy conversion efficiency above 20% has now been certified, improved understanding of the material properties contributing to these high performance levels may allow the progression to even higher efficiency, stable cells. The optical properties of these new materials are important not only to device design but also because of the insight they provide into less directly accessible properties, including energy-band structures, binding energies, and likely impact of excitons, as well as into absorption and inverse radiative recombination processes. PMID:26560862

  13. Analysis and modeling of alkali halide aqueous solutions

    DEFF Research Database (Denmark)

    Kim, Sun Hyung; Anantpinijwatna, Amata; Kang, Jeong Won;

    2016-01-01

    calculations for various electrolyte properties of alkali halide aqueous solutions such as mean ionic activity coefficients, osmotic coefficients, and salt solubilities. The model covers highly nonideal electrolyte systems such as lithium chloride, lithium bromide and lithium iodide, that is, systems that are...... very soluble in water, for example, up to more than 30 mol kg-1. Phase behaviors for the systems are analyzed at concentrations of salt up to the solubility in water at temperatures between 273 and 373 K by comparing calculated results with available experimental data and available models....

  14. Dengue and Calcium

    OpenAIRE

    Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

    2014-01-01

    Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium...

  15. Measurements of intracellular calcium

    International Nuclear Information System (INIS)

    Intracellular calcium concentration ([Ca2+]i) has been measured in cultured cells by using Fura-2 load cells and a computer-controlled Perkin Elmer LS-5B spectrofluorometer. Increased [Ca2+]i in cells exposed to extracellular bilirubin was observed both with and without extracellular calcium. However, the increase was considerable larger with extracellular calcium. The enhancement of [Ca2+]i became smaller with decreasing bilirubin/BSA (bovine serum albumine) ratio. 5 refs., 5 figs

  16. Halide salts accelerate degradation of high explosives by zerovalent iron

    International Nuclear Information System (INIS)

    Zerovalent iron (Fe0, ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl- and Br- was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br- was present in solution. - The addition of halide ions promotes the degradation of high explosives by zerovalent iron

  17. Structure and Bonding in Small Neutral Alkali-Halide Clusters

    CERN Document Server

    Aguado, A; López, J M; Alonso, J A

    1997-01-01

    The structural and bonding properties of small neutral alkali-halide clusters (AX)n, with n less than or equal to 10, A=Li, Na, K, Rb and X=F, Cl, Br, I, are studied using the ab initio Perturbed Ion (aiPI) model and a restricted structural relaxation criterion. A trend of competition between rock-salt and hexagonal ring-like isomers is found and discussed in terms of the relative ionic sizes. The main conclusion is that an approximate value of r_C/r_A=0.5 (where r_C and r_A are the cationic and anionic radii) separates the hexagonal from the rock-salt structures. The classical electrostatic part of the total energy at the equilibrium geometry is enough to explain these trends. The magic numbers in the size range studied are n= 4, 6 and 9, and these are universal since they occur for all alkali-halides and do not depend on the specific ground state geometry. Instead those numbers allow for the formation of compact clusters. Full geometrical relaxations are considered for (LiF)n (n=3-7) and (AX)_3 clusters, an...

  18. Melting and liquid structure of polyvalent metal halides

    International Nuclear Information System (INIS)

    A short review is given of recent progress in determining and understanding liquid structure types and melting mechanisms for halides of polyvalent metals. The nature of the preferred local coordination for the polyvalent metal ion in the melt can usually be ascertained from data on liquid mixtures with halogen-donating alkali halides. The stability of these local coordination states and the connectivity that arises between them in the approach to the pure melt determines the character of its short-range and possible medium-range order. A broad classification of structural and melting behaviours can be given on the basis of measured melting parameters and transport coefficients for many compounds, in combination with the available diffraction data on the liquid structure of several compounds. Correlations have been shown to exist with a simple indicator of the nature of the chemical bond and also with appropriate parameters of ionic models, wherever the latter are usefully applicable for semiquantitative calculations of liquid structure. Consequences on the mechanisms for valence electron localization in solutions of metallic elements into strongly structured molten salts are also briefly discussed. (author). 46 refs, 4 figs, 2 tabs

  19. Tunable Near-Infrared Luminescence in Tin Halide Perovskite Devices.

    Science.gov (United States)

    Lai, May L; Tay, Timothy Y S; Sadhanala, Aditya; Dutton, Siân E; Li, Guangru; Friend, Richard H; Tan, Zhi-Kuang

    2016-07-21

    Infrared emitters are reasonably rare in solution-processed materials. Recently, research into hybrid organo-lead halide perovskite, originally popular in photovoltaics,1-3 has gained traction in light-emitting diodes (LED) due to their low-cost solution processing and good performance.4-9 The lead-based electroluminescent materials show strong colorful emission in the visible region, but lack emissive variants further in the infrared. The concerns with the toxicity of lead may, additionally, limit their wide-scale applications. Here, we demonstrate tunable near-infrared electroluminescence from a lead-free organo-tin halide perovskite, using an ITO/PEDOT:PSS/CH3NH3Sn(Br1-xIx)3/F8/Ca/Ag device architecture. In our tin iodide (CH3NH3SnI3) LEDs, we achieved a 945 nm near-infrared emission with a radiance of 3.4 W sr(-1) m(-2) and a maximum external quantum efficiency of 0.72%, comparable with earlier lead-based devices. Increasing the bromide content in these tin perovskite devices widens the semiconductor bandgap and leads to shorter wavelength emissions, tunable down to 667 nm. These near-infrared LEDs could find useful applications in a range of optical communication, sensing and medical device applications. PMID:27336412

  20. A new polarizable force field for alkali and halide ions

    International Nuclear Information System (INIS)

    We developed transferable potentials for alkali and halide ions which are consistent with our recent model of water [P. T. Kiss and A. Baranyai, J. Chem. Phys. 138, 204507 (2013)]. Following the approach used for the water potential, we applied Gaussian charge distributions, exponential repulsion, and r−6 attraction. One of the two charges of the ions is fixed to the center of the particle, while the other is connected to this charge by a harmonic spring to express polarization. Polarizability is taken from quantum chemical calculations. The repulsion between different species is expressed by the combining rule of Kong [J. Chem. Phys. 59, 2464 (1972)]. Our primary target was the hydration free energy of ions which is correct within the error of calculations. We calculated water-ion clusters up to 6 water molecules, and, as a crosscheck, we determined the density and internal energy of alkali-halide crystals at ambient conditions with acceptable accuracy. The structure of hydrated ions was also discussed

  1. Dislocation unpinning model of acoustic emission from alkali halide crystals

    Indian Academy of Sciences (India)

    B P Chandra; Anubha S Gour; Vivek K Chandra; Yuvraj Patil

    2004-06-01

    The present paper reports the dislocation unpinning model of acoustic emission (AE) from alkali halide crystals. Equations are derived for the strain dependence of the transient AE pulse rate, peak value of the AE pulse rate and the total number of AE pulse emitted. It is found that the AE pulse rate should be maximum for a particular strain of the crystals. The peak value of the AE pulse rate should depend on the volume and strain rate of the crystals, and also on the pinning time of dislocations. Since the pinning time of dislocations decreases with increasing strain rate, the AE pulse rate should be weakly dependent on the strain rate of the crystals. The total number of AE should increase linearly with deformation and then it should attain a saturation value for the large deformation. By measuring the strain dependence of the AE pulse rate at a fixed strain rate, the time constant $_{\\text{s}}$ for surface annihilation of dislocations and the pinning time $_{\\text{p}}$ of the dislocations can be determined. A good agreement is found between the theoretical and experimental results related to the AE from alkali halide crystals.

  2. Two-Dimensional Halide Perovskites: Tuning Electronic Activities of Defects.

    Science.gov (United States)

    Liu, Yuanyue; Xiao, Hai; Goddard, William A

    2016-05-11

    Two-dimensional (2D) halide perovskites are emerging as promising candidates for nanoelectronics and optoelectronics. To realize their full potential, it is important to understand the role of those defects that can strongly impact material properties. In contrast to other popular 2D semiconductors (e.g., transition metal dichalcogenides MX2) for which defects typically induce harmful traps, we show that the electronic activities of defects in 2D perovskites are significantly tunable. For example, even with a fixed lattice orientation one can change the synthesis conditions to convert a line defect (edge or grain boundary) from electron acceptor to inactive site without deep gap states. We show that this difference originates from the enhanced ionic bonding in these perovskites compared with MX2. The donors tend to have high formation energies and the harmful defects are difficult to form at a low halide chemical potential. Thus, we unveil unique properties of defects in 2D perovskites and suggest practical routes to improve them. PMID:27100910

  3. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  4. Formability of ABX3 (X = F, Cl, Br, I) halide perovskites.

    Science.gov (United States)

    Li, Chonghea; Lu, Xionggang; Ding, Weizhong; Feng, Liming; Gao, Yonghui; Guo, Ziming

    2008-12-01

    In this study a total of 186 complex halide systems were collected; the formabilities of ABX3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. A model for halide perovskite formability was built up. In this model obtained, for all 186 complex halides systems, only one system (CsF-MnF2) without perovskite structure and six systems (RbF-PbF2, CsF-BeF2, KCl-FeCl2, TlI-MnI2, RbI-SnI2, TlI-PbI2) with perovskite structure were wrongly classified, so its predicting accuracy reaches 96%. It is also indicated that both the tolerance factor and the octahedral factor are a necessary but not sufficient condition for ABX3 halide perovskite formability, and a lowest limit of the octahedral factor exists for halide perovskite formation. This result is consistent with our previous report for ABO3 oxide perovskite, and may be helpful to design novel halide materials with the perovskite structure. PMID:19029699

  5. Serum Calcium Level in Hypertension

    OpenAIRE

    Hazari, Mohammed Abdul Hannan; Arifuddin, Mehnaaz Sameera; Muzzakar, Syed; Reddy, Vontela Devender

    2012-01-01

    Background: The alterations in extracellular calcium level may influence intracellular calcium level and possibly play a role in the pathogenesis of essential hypertension. Aim: The purpose was to find out the association between serum calcium levels and hypertension; and to compare the serum calcium levels between normotensive controls, hypertensive subjects on calcium channel blockers, and hypertensive subjects on antihypertensive medication other than calcium channel blockers. Materials an...

  6. Investigation of change regularity of energy states of Mn2+ in halides

    International Nuclear Information System (INIS)

    Data on 4E, 4A1 (4G) and 4T1 (4G) energy states of Mn2+ ion in some halides have been obtained and analyzed. With use of the dielectric theory of the chemical bond for complex crystals, several chemical bond parameters were calculated. The change regularity of the energy states of Mn2+ in halides has been studied. The results show that the covalence, the coordination number and the radius of the central ion are the main factors influencing the energy states of Mn2+ ion in halides. The relationships between these factors and the energy state 4T1 (4G), the energy difference ΔE (ΔE=4E, 4A1 (4G)→4T1 (4G)) of Mn2+ ion in halides were established: E=2.0898+0.8618 exp (−F/0.2431); ΔE=0.3201+0.9713⁎F. These relationships allow us to predict the position of energy state 4T1 (4G) and the energy difference ΔE of Mn2+ in halides. This work can be significant for further understanding the luminescent properties of Mn2+ and can be used to develop new Mn2+-doped phosphors. - Highlights: ► Relationship between F and energy state 4T1(4G) of Mn2+ in halides was set up. ► Relationship between F and energy difference ΔE of Mn2+ in halides was set up. ► Site occupation of Mn2+-doped halides with two or more cations can be made clear. ► Energy state 4T1(4G) and emission band of Mn2+ in halides can be predicted.

  7. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free calciu

  8. Mild Palladium-Catalyzed Cyanation of (Hetero)aryl Halides and Triflates in Aqueous Media

    OpenAIRE

    Cohen, Daniel T.; Buchwald, Stephen L.

    2015-01-01

    A mild, efficient, and low-temperature palladium-catalyzed cyanation of (hetero)aryl halides and triflates is reported. Previous palladium-catalyzed cyanations of (hetero)aryl halides have required higher temperatures to achieve good catalytic activity. This current reaction allows the cyanation of a general scope of (hetero)aryl halides and triflates at 2–5 mol % catalyst loadings with temperatures ranging from rt to 40 °C. This mild method was applied to the synthesis of lersivirine, a reve...

  9. Energetics of the ruthenium-halide bond in olefin metathesis (pre)catalysts

    KAUST Repository

    Falivene, Laura

    2013-01-01

    A DFT analysis of the strength of the Ru-halide bond in a series of typical olefin metathesis (pre)catalysts is presented. The calculated Ru-halide bond energies span the rather broad window of 25-43 kcal mol-1. This indicates that in many systems dissociation of the Ru-halide bond is possible and is actually competitive with dissociation of the labile ligand generating the 14e active species. Consequently, formation of cationic Ru species in solution should be considered as a possible event. © 2013 The Royal Society of Chemistry.

  10. Neutron Activation Analysis of Lead Halide Pollution Aerosols

    International Nuclear Information System (INIS)

    Iodine, bromine and chlorine have been determined by neutron activation analysis in atmospheric samples of both natural and pollution origin, and a comparison of the two sources provides the basis of a technique described in this paper for determining the composition and possible source of lead halide pollution aerosols. The activation analysis procedure employed consists of reactor neutron irradiation of aqueous samples and comparators for 20 min followed by radiochemical separation of iodine, bromine and chlorine and automatic counting of beta radioactivity from solid silver halide sources. Determination of lead by anodic stripping voltammetry (inverse polarography) consists of deposition of Pb++ from the solution onto a composite paraffin- impregnated graphite and mercury electrode at -1.00 V versus the standard calomel electrode, and then stripping by increasing the potential continuously. A significant question of public health interest in the air chemistry of lead is the source of the lead. Ethyl fluid, a mixture of organic lead, bromine and chlorine compounds, burns to form inorganic lead halide particles with Cl/Pb = 0.34 and Br/Pb = 0.39 by weight. In Cambridge, Massachusetts, analyses of cascade impactor aerosols were compared with similarly collected samples from the unpolluted air of Hawaii. The pollution bromine component ranged from 0.4 to 0.1 or less of the lead concentration, indicating in most cases either automotive lead with a bromine deficiency or a mixture of lead from automotive and other sources. In Fairbanks, Alaska, during winter, atmospheric conditions favour high local concentrations of air pollutants. Aerosols collected by Millipore filters show that pollution chlorine averages very nearly the value predicted from the observed lead and the known composition of ethyl fluid, and the automotive source for both chlorine and lead is strongly indicated. Pollution bromine, however, was less than predicted, and the bromine deficiency was about

  11. Theoretical study of the scandium and yttrium halides

    Science.gov (United States)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Partridge, Harry

    1988-01-01

    The X1Sigma(+) ground states and a3Delta excited states of the diatomic halides of Sc and Y are characterized theoretically, using the SDCI coupled-pair functional method and the state-averaged CASSCF method to determine the spectroscopic constants and related properties. The techniques employed are discussed, and the results are presented in extensive tables. The dissociation energies are given as D0 = 6.00 eV for ScF, 4.55 eV for ScCl, 3.90 eV for ScBr, 6.72 eV for YF, 5.36 eV for YCl, and 4.74 eV for YBr.

  12. Material Innovation in Advancing Organometal Halide Perovskite Functionality.

    Science.gov (United States)

    Zheng, Fan; Saldana-Greco, Diomedes; Liu, Shi; Rappe, Andrew M

    2015-12-01

    Organometal halide perovskites (OMHPs) have garnered much attention recently for their unprecedented rate of increasing power conversion efficiency (PCE), positioning them as a promising basis for the next-generation photovoltaic devices. However, the gap between the rapid increasing PCE and the incomplete understanding of the structure-property-performance relationship prevents the realization of the true potential of OMHPs. This Perspective aims to provide a concise overview of the current status of OMHP research, highlighting the unique properties of OMHPs that are critical for solar applications but still not adequately explained. Stability and performance challenges of OMHP solar cells are discussed, calling upon combined experimental and theoretical efforts to address these challenges for pioneering commercialization of OMHP solar cells. Various material innovation strategies for improving the performance and stability of OMHPs are surveyed, showing that the OMHP architecture can serve as a promising and robust platform for the design and optimization of materials with desired functionalities. PMID:26631361

  13. Quasielastic neutron scattering study of silver selenium halides

    CERN Document Server

    Major, A G; Barnes, A C; Howells, W S

    2002-01-01

    Both silver chalcogenides (Ag sub 2 S, Ag sub 2 Se, and Ag sub 2 Te) and silver halides (AgCl, AgBr, and AgI) are known to be fast-ion solids in which the silver ions can diffuse quickly in a sublattice formed by the other ions. To clarify whether mixtures of these materials (such as Ag sub 3 SeI) possess comparable properties and whether a systematic dependence on the cation-to-anion ratio can be observed, some of these mixtures were studied by quasielastic neutron scattering both in the solid and the liquid phases. To identify the diffusion mechanisms and constants, a new data-analysis method based on a two-dimensional maximum-likelihood fit is proposed. This method has the potential to give more reliable information on the diffusion mechanism than the traditional Bayesian method. (orig.)

  14. Theory of freezing of alkali halides and binary alloys

    International Nuclear Information System (INIS)

    Using the basic equations of classical statistical mechanics relating the singlet densities rho1 and rho2 of a binary system to the three partial direct correlation functions csub(ij), a theory of freezing is developed. Though the theory is set up for arbitrary concentration, we focus on the freezing of the alkali halides. In particular, we show that periodic solutions of the equations for rho1 and rho2 can coexist with homogeneous solutions. The difference in free energy between periodic and homogeneous phases is built up in terms of (i) the volume difference and (ii) the Fourier components of rho1, rho2 and csub(ij). To lowest order, it is stressed that the freezing transition is determined by the charge-charge structure factor at the principal peak and by the compressibility. (author)

  15. Fabrication of alkali halide UV photocathodes by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Brendel' , V M; Bukin, V V; Garnov, Sergei V; Bagdasarov, V Kh; Denisov, N N; Garanin, Sergey G; Terekhin, V A; Trutnev, Yurii A

    2012-12-31

    A technique has been proposed for the fabrication of atmospheric corrosion resistant alkali halide UV photocathodes by pulsed laser deposition. We produced photocathodes with a highly homogeneous photoemissive layer well-adherent to the substrate. The photocathodes were mounted in a vacuum photodiode, and a tungsten grid was used as an anode. Using pulsed UV lasers, we carried out experiments aimed at evaluating the quantum efficiency of the photocathodes. With a dc voltage applied between the photocathode and anode grid, we measured a shunt signal proportional to the total charge emitted by the cathode exposed to UV laser light. The proposed deposition technique enables one to produce photocathodes with photoemissive layers highly uniform in quantum efficiency, which is its main advantage over thin film growth by resistive evaporation. (laser technologies)

  16. Fabrication of alkali halide UV photocathodes by pulsed laser deposition

    Science.gov (United States)

    Brendel', V. M.; Bukin, V. V.; Garnov, Sergei V.; Bagdasarov, V. Kh; Denisov, N. N.; Garanin, Sergey G.; Terekhin, V. A.; Trutnev, Yurii A.

    2012-12-01

    A technique has been proposed for the fabrication of atmospheric corrosion resistant alkali halide UV photocathodes by pulsed laser deposition. We produced photocathodes with a highly homogeneous photoemissive layer well-adherent to the substrate. The photocathodes were mounted in a vacuum photodiode, and a tungsten grid was used as an anode. Using pulsed UV lasers, we carried out experiments aimed at evaluating the quantum efficiency of the photocathodes. With a dc voltage applied between the photocathode and anode grid, we measured a shunt signal proportional to the total charge emitted by the cathode exposed to UV laser light. The proposed deposition technique enables one to produce photocathodes with photoemissive layers highly uniform in quantum efficiency, which is its main advantage over thin film growth by resistive evaporation.

  17. Games people play with interstitials (in alkali halides)

    International Nuclear Information System (INIS)

    A survey is given of the various ways in which interstitial halogen atoms produced by ionising radiation can be trapped in alkali halides. First, the fundamental interstitial halogen atom center, the H-center, is discussed. Then, interstitial centers trapped by, or in the neighbourhood of, various impurities are presented. Particular attention is given to trapping by the following impurities: foreign halogen ions, foreign alkali ions or pairs of both. The discussion is limited to a description of the production and the models of these H-type centers and little is said about their sometimes interesting physical properties. A few speculations are offered why certain interstitial centers have not yet been observed. The models of a few paramagnetic diinterstitial centers are also presented

  18. Giant photostriction in organic-inorganic lead halide perovskites

    Science.gov (United States)

    Zhou, Yang; You, Lu; Wang, Shiwei; Ku, Zhiliang; Fan, Hongjin; Schmidt, Daniel; Rusydi, Andrivo; Chang, Lei; Wang, Le; Ren, Peng; Chen, Liufang; Yuan, Guoliang; Chen, Lang; Wang, Junling

    2016-04-01

    Among the many materials investigated for next-generation photovoltaic cells, organic-inorganic lead halide perovskites have demonstrated great potential thanks to their high power conversion efficiency and solution processability. Within a short period of about 5 years, the efficiency of solar cells based on these materials has increased dramatically from 3.8 to over 20%. Despite the tremendous progress in device performance, much less is known about the underlying photophysics involving charge-orbital-lattice interactions and the role of the organic molecules in this hybrid material remains poorly understood. Here, we report a giant photostrictive response, that is, light-induced lattice change, of >1,200 p.p.m. in methylammonium lead iodide, which could be the key to understand its superior optical properties. The strong photon-lattice coupling also opens up the possibility of employing these materials in wireless opto-mechanical devices.

  19. Mechanical properties of silver halide core/clad IR fibers

    Science.gov (United States)

    Shalem, Shaul; German, Alla; Moser, Frank; Katzir, Abraham

    1996-04-01

    We have developed core/clad polycrystalline silver halide optical fibers with a loss of roughly 0.3 dB/m at 10.6 micrometers. Such fibers, with core diameters 0.3 - 0.6 mm and lengths of 1 to 2 meters are capable of continuously delivering output power densities as high as 14 KW/cm2. The fibers were repetitively bent in the plastic and elastic regimes and the optical transmission monitored during bending. The mechanical properties of the core/clad fibers and of the core only fibers are similar. It was also demonstrated that the 'bending' properties of the core/clad fibers are determined by the cladding material. Our investigations suggest that proper design of the core/clad structure may give significant improvement in mechanical properties such as more cycles to optical failure. This will be very important especially for endoscopic laser surgery and other medical applications.

  20. Strong Turbulence in Alkali Halide Negative Ion Plasmas

    Science.gov (United States)

    Sheehan, Daniel

    1999-11-01

    Negative ion plasmas (NIPs) are charge-neutral plasmas in which the negative charge is dominated by negative ions rather than electrons. They are found in laser discharges, combustion products, semiconductor manufacturing processes, stellar atmospheres, pulsar magnetospheres, and the Earth's ionosphere, both naturally and man-made. They often display signatures of strong turbulence^1. Development of a novel, compact, unmagnetized alkali halide (MX) NIP source will be discussed, it incorporating a ohmically-heated incandescent (2500K) tantulum solenoid (3cm dia, 15 cm long) with heat shields. The solenoid ionizes the MX vapor and confines contaminant electrons, allowing a very dry (electron-free) source. Plasma densities of 10^10 cm-3 and positive to negative ion mass ratios of 1 Fusion 4, 91 (1978).

  1. Ultraviolet optical absorption of alkali cyanides and alkali halide cyanides

    International Nuclear Information System (INIS)

    The ultraviolet absorption spectra of alkali cyanide and mixed alkali halide cyanide crystals were measured at temperatures ranging from 300K down to 4.2K. A set of small absorption peaks was observed at energies near 6 eV and assigned to parity forbidden X1Σ+→a'3Σ+ transitions of the CN- molecular ions. It was observed that the peak position depends on the alkali atom while the absorption cross section strongly depends on the halogen and on the CN- concentration of the mixed crystals. These effects are explained in terms of an interaction between the triplet molecular excitons and charge transfer excitons. The experimental data were fit with a coupling energy of a few meV. The coupling mechanism is discussed and it is found to be due to the overlap between the wave functions of the two excitations. (Author)

  2. Two-photon pumped lead halide perovskite nanowire lasers

    CERN Document Server

    Gu, Zhiyuan; Sun, Wenzhao; Li, Jinakai; Liu, Shuai; Song, Qinghai; Xiao, Shumin

    2015-01-01

    Solution-processed lead halide perovskites have shown very bright future in both solar cells and microlasers. Very recently, the nonlinearity of perovskites started to attract considerable research attention. Second harmonic generation and two-photon absorption have been successfully demonstrated. However, the nonlinearity based perovskite devices such as micro- & nano- lasers are still absent. Here we demonstrate the two-photon pumped nanolasers from perovskite nanowires. The CH3NH3PbBr3 perovskite nanowires were synthesized with one-step solution self-assembly method and dispersed on glass substrate. Under the optical excitation at 800 nm, two-photon pumped lasing actions with periodic peaks have been successfully observed at around 546 nm. The obtained quality (Q) factors of two-photon pumped nanolasers are around 960, and the corresponding thresholds are about 674?J=cm2. Both the Q factors and thresholds are comparable to conventional whispering gallery modes in two-dimensional polygon microplates. Ou...

  3. Giant photostriction in organic–inorganic lead halide perovskites

    Science.gov (United States)

    Zhou, Yang; You, Lu; Wang, Shiwei; Ku, Zhiliang; Fan, Hongjin; Schmidt, Daniel; Rusydi, Andrivo; Chang, Lei; Wang, Le; Ren, Peng; Chen, Liufang; Yuan, Guoliang; Chen, Lang; Wang, Junling

    2016-01-01

    Among the many materials investigated for next-generation photovoltaic cells, organic–inorganic lead halide perovskites have demonstrated great potential thanks to their high power conversion efficiency and solution processability. Within a short period of about 5 years, the efficiency of solar cells based on these materials has increased dramatically from 3.8 to over 20%. Despite the tremendous progress in device performance, much less is known about the underlying photophysics involving charge–orbital–lattice interactions and the role of the organic molecules in this hybrid material remains poorly understood. Here, we report a giant photostrictive response, that is, light-induced lattice change, of >1,200 p.p.m. in methylammonium lead iodide, which could be the key to understand its superior optical properties. The strong photon-lattice coupling also opens up the possibility of employing these materials in wireless opto-mechanical devices. PMID:27044485

  4. Phase space investigation of the lithium amide halides

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Rosalind A. [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Hydrogen and Fuel Cell Group, School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Hewett, David R.; Korkiakoski, Emma [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Thompson, Stephen P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Anderson, Paul A., E-mail: p.a.anderson@bham.ac.uk [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • The lower limits of halide incorporation in lithium amide have been investigated. • The only amide iodide stoichiometry observed was Li{sub 3}(NH{sub 2}){sub 2}I. • Solid solutions were observed in both the amide chloride and amide bromide systems. • A 46% reduction in chloride content resulted in a new phase: Li{sub 7}(NH{sub 2}){sub 6}Cl. • New low-chloride phase maintained improved H{sub 2} desorption properties of Li{sub 4}(NH{sub 2}){sub 3}Cl. - Abstract: An investigation has been carried out into the lower limits of halide incorporation in lithium amide (LiNH{sub 2}). It was found that the lithium amide iodide Li{sub 3}(NH{sub 2}){sub 2}I was unable to accommodate any variation in stoichiometry. In contrast, some variation in stoichiometry was accommodated in Li{sub 7}(NH{sub 2}){sub 6}Br, as shown by a decrease in unit cell volume when the bromide content was reduced. The amide chloride Li{sub 4}(NH{sub 2}){sub 3}Cl was found to adopt either a rhombohedral or a cubic structure depending on the reaction conditions. Reduction in chloride content generally resulted in a mixture of phases, but a new rhombohedral phase with the stoichiometry Li{sub 7}(NH{sub 2}){sub 6}Cl was observed. In comparison to LiNH{sub 2}, this new low-chloride phase exhibited similar improved hydrogen desorption properties as Li{sub 4}(NH{sub 2}){sub 3}Cl but with a much reduced weight penalty through addition of chloride. Attempts to dope lithium amide with fluoride ions have so far proved unsuccessful.

  5. Phase space investigation of the lithium amide halides

    International Nuclear Information System (INIS)

    Highlights: • The lower limits of halide incorporation in lithium amide have been investigated. • The only amide iodide stoichiometry observed was Li3(NH2)2I. • Solid solutions were observed in both the amide chloride and amide bromide systems. • A 46% reduction in chloride content resulted in a new phase: Li7(NH2)6Cl. • New low-chloride phase maintained improved H2 desorption properties of Li4(NH2)3Cl. - Abstract: An investigation has been carried out into the lower limits of halide incorporation in lithium amide (LiNH2). It was found that the lithium amide iodide Li3(NH2)2I was unable to accommodate any variation in stoichiometry. In contrast, some variation in stoichiometry was accommodated in Li7(NH2)6Br, as shown by a decrease in unit cell volume when the bromide content was reduced. The amide chloride Li4(NH2)3Cl was found to adopt either a rhombohedral or a cubic structure depending on the reaction conditions. Reduction in chloride content generally resulted in a mixture of phases, but a new rhombohedral phase with the stoichiometry Li7(NH2)6Cl was observed. In comparison to LiNH2, this new low-chloride phase exhibited similar improved hydrogen desorption properties as Li4(NH2)3Cl but with a much reduced weight penalty through addition of chloride. Attempts to dope lithium amide with fluoride ions have so far proved unsuccessful

  6. Neuronal calcium sparks and intracellular calcium “noise”

    OpenAIRE

    Melamed-Book, Naomi; Kachalsky, Sylvia G.; Kaiserman, Igor; Rahamimoff, Rami

    1999-01-01

    Intracellular calcium ions are involved in many forms of cellular function. To accommodate so many control functions, a complex spatiotemporal organization of calcium signaling has developed. In both excitable and nonexcitable cells, calcium signaling was found to fluctuate. Sudden localized increases in the intracellular calcium concentration—or calcium sparks—were found in heart, striated and smooth muscle, Xenopus Laevis oocytes, and HeLa and P12 cells. In the nervous system, intracellular...

  7. NEW THIO S2- ADDUCTS WITH ANTIMONY (III AND V HALIDE: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    HASSAN ALLOUCH

    2013-12-01

    Full Text Available Five new S2- adducts with SbIII and SbV halides have been synthesized and studied by infrared. Discrete structures have been suggested, the environment around the antimony being tetrahedral, trigonal bipyramidal or octahedral.

  8. Methods for synthesizing alane without the formation of adducts and free of halides

    Science.gov (United States)

    Zidan, Ragaiy; Knight, Douglas A; Dinh, Long V

    2013-02-19

    A process is provided to synthesize an alane without the formation of alane adducts as a precursor. The resulting product is a crystallized .alpha.-alane and is a highly stable product and is free of halides.

  9. Palladium-catalyzed Cascade Cyclization-Coupling Reaction of Benzyl Halides with N,N-Diallylbenzoylamide

    Institute of Scientific and Technical Information of China (English)

    Yi Min HU; Yu ZHANG; Jian Lin HAN; Cheng Jian ZHU; Yi PAN

    2003-01-01

    A novel type of palladium-catalyzed cascade cyclization-coupling reaction has been found. Reaction of N, N-diallylbenzoylamide 1 with benzyl halides 2 afforded the corresponding dihydropyrroles 3 in moderate to excellent yields.

  10. Efficiency of energy transfer from γ-irradiated ammonium halides in aqueous iodide and nitrate solutions

    International Nuclear Information System (INIS)

    It is well known that ammonium halide (NH4X) crystals, on γ-exposure, store energy in the form of primary and secondary radiolytic products. Such crystals on dissolution in aqueous iodide and nitrate solutions result in oxidation of iodide and reduction of nitrate, respectively. The yields of iodine and nitrite are determined by chemical methods under varying conditions of the amount, dose and particle size of the irradiated ammonium halide salts. The maximum values of the efficiency of energy transfer for oxidation and reduction processes for ammonium halide salts correspond to 40% and 10%, respectively. At low doses, an empirical relation proposed between the percent efficiency of energy transfer and the absorbed dose is valid. The concentrations of inherent oxidizing and reducing species initially present are 7.0*1018 and 1.0*1018 per mol of ammonium halide, respectively. (author) 21 refs.; 7 figs.; 2 tabs

  11. Approaching Bulk Carrier Dynamics in Organo-Halide Perovskite Nanocrystalline Films by Surface Passivation.

    Science.gov (United States)

    Stewart, Robert J; Grieco, Christopher; Larsen, Alec V; Maier, Joshua J; Asbury, John B

    2016-04-01

    The electronic properties of organo-halide perovskite absorbers described in the literature have been closely associated with their morphologies and processing conditions. However, the underlying origins of this dependence remain unclear. A combination of inorganic synthesis, surface chemistry, and time-resolved photoluminescence spectroscopy was used to show that charge recombination centers in organo-halide perovskites are almost exclusively localized on the surfaces of the crystals rather than in the bulk. Passivation of these surface defects causes average charge carrier lifetimes in nanocrystalline thin films to approach the bulk limit reported for single-crystal organo-halide perovskites. These findings indicate that the charge carrier lifetimes of perovskites are correlated with their thin-film processing conditions and morphologies through the influence these have on the surface chemistry of the nanocrystals. Therefore, surface passivation may provide a means to decouple the electronic properties of organo-halide perovskites from their thin-film processing conditions and corresponding morphologies. PMID:26966792

  12. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk;

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... calcium binds silicon primarily as calcium silicates and less as potassium calcium silicates....

  13. Space-dependent self-diffusion processes in molten copper halides: a molecular dynamics study

    OpenAIRE

    Alcaraz Sendra, Olga; Trullàs Simó, Joaquim

    2001-01-01

    This work is concerned with single ion dynamics in molten copper halides (CuI and CuCl) which exhibit fast ionic conduction before melting. The self-dynamic structure factor of the two ionic species in each melt have been calculated by molecular dynamics simulations and the corresponding effective wavelength-dependent self-diffusion coefficients have been studied. The results have been compared with those obtained for molten alkali halides (KCl and RbCl).

  14. Atomistic simulation of ion solvation in water explains surface preference of halides

    OpenAIRE

    Caleman, C.; Hub, J. S.; van Maaren, P.; van der Spoel, D

    2011-01-01

    Water is a demanding partner. It strongly attracts ions, yet some halide anions—chloride, bromide, and iodide—are expelled to the air/water interface. This has important implications for chemistry in the atmosphere, including the ozone cycle. We present a quantitative analysis of the energetics of ion solvation based on molecular simulations of all stable alkali and halide ions in water droplets. The potentials of mean force for Cl-, Br-, and I- have shallow minima near the surface. We demons...

  15. Influence of electrode, buffer gas and control gear on metal halide lamp performance

    International Nuclear Information System (INIS)

    In this paper the influence of electrode composition, buffer gas fill pressure and control gear on the performance of metal halide lamps is investigated. It is shown that pure tungsten electrodes improve lumen maintenance and reduce voltage rise over lamp life. An optimum buffer gas fill pressure condition is discovered which allows for reduced electrode erosion during lamp starting as well as under normal operating conditions. Use of electronic control gear is shown to improve the performance of metal halide lamps

  16. Organometallic halide perovskite single crystals having low deffect density and methods of preparation thereof

    KAUST Repository

    Bakr, Osman M.

    2016-02-18

    The present disclosure presents a method of making a single crystal organometallic halide perovskites, with the formula: AMX3, wherein A is an organic cation, M is selected from the group consisting of: Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, and Eu, and X is a halide. The method comprises the use of two reservoirs containing different precursors and allowing the vapor diffusion from one reservoir to the other one. A solar cell comprising said crystal is also disclosed.

  17. The effect of low solublility organic acids on the hygroscopicity of sodium halide aerosols

    OpenAIRE

    L. Miñambres; Méndez, E; Sánchez, M. N.; Castaño, F.; F. J. Basterretxea

    2014-01-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be performed in this study. The hygroscopic properties of sodium halide submicrometer particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were gen...

  18. The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols

    OpenAIRE

    L. Miñambres; Méndez, E; Sánchez, M. N.; Castaño, F.; F. J. Basterretxea

    2014-01-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be investigated in this study. The hygroscopic properties of sodium halide sub-micrometre particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles w...

  19. Research Update: Physical and electrical characteristics of lead halide perovskites for solar cell applications

    OpenAIRE

    Bretschneider, Simon A.; Jonas Weickert; James A. Dorman; Lukas Schmidt-Mende

    2014-01-01

    The field of thin-film photovoltaics has been recently enriched by the introduction of lead halide perovskites as absorber materials, which allow low-cost synthesis of solar cells with efficiencies exceeding 16%. The exact impact of the perovskite crystal structure and composition on the optoelectronic properties of the material are not fully understood. Our progress report highlights the knowledge gained about lead halide perovskites with a focus on physical and optoelectronic properties. We...

  20. Oxidation of hydrogen halides to elemental halogens with catalytic molten salt mixtures

    Science.gov (United States)

    Rohrmann, Charles A.

    1978-01-01

    A process for oxidizing hydrogen halides by means of a catalytically active molten salt is disclosed. The subject hydrogen halide is contacted with a molten salt containing an oxygen compound of vanadium and alkali metal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen. The reduced vanadium which remains after this contacting is regenerated to the active higher valence state by contacting the spent molten salt with a stream of oxygen-bearing gas.

  1. Nickel-Catalyzed Regiodivergent Opening of Epoxides with Aryl Halides: Co-Catalysis Controls Regioselectivity

    OpenAIRE

    Zhao, Yang; Weix, Daniel J.

    2013-01-01

    Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the co-catalyst employed. Iodide co-catalysis results in opening at the less hindered position via an iodohydrin intermediate. Titan...

  2. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  3. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate ab

  4. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  5. Reactivity of TEMPO anion as a nucleophile and its applications for selective transformations of haloalkanes or acyl halides to aldehydes

    OpenAIRE

    Inokuchi, Tsutomu; Kawafuchi, Hiroyuki

    2004-01-01

    Sodium 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO−Na+), generated by reduction of TEMPO· with sodium naphthalenide in THF, reacted with alkyl halides or acyl halides to produce O-alkylated or acylated TEMPOs, which were in turn oxidized with mCPBA or reduced with DIBAL-H to afford the corresponding aldehydes, thus accomplishing a new protocol for the halides-carbonyls conversion.

  6. Double-Diffusive Convection During Growth of Halides and Selenides

    Science.gov (United States)

    Singh, N. B.; Su, Ching-Hua; Duval, Walter M. B.

    2015-01-01

    Heavy metal halides and selenides have unique properties which make them excellent materials for chemical, biological and radiological sensors. Recently it has been shown that selenohalides are even better materials than halides or selenides for gamma-ray detection. These materials also meet the strong needs of a wide band imaging technology to cover ultra-violet (UV), midwave infrared wavelength (MWIR) to very long wavelength infrared (VLWIR) region for hyperspectral imager components such as etalon filters and acousto-optic tunable filters (AO). In fact AOTF based imagers based on these materials have some superiority than imagers based on liquid crystals, FTIR, Fabry-Perot, grating, etalon, electro-optic modulation, piezoelectric and several other concepts. For example, broadband spectral and imagers have problems of processing large amount of information during real-time observation. Acousto-Optic Tunable Filter (AOTF) imagers are being developed to fill the need of reducing processing time of data, low cost operation and key to achieving the goal of covering long-wave infrared (LWIR). At the present time spectral imaging systems are based on the use of diffraction gratings are typically used in a pushbroom or whiskbroom mode. They are mostly used in systems and acquire large amounts of hyperspectral data that is processed off-line later. In contrast, acousto-optic tunable filter spectral imagers require very little image processing, providing new strategies for object recognition and tracking. They are ideally suited for tactical situations requiring immediate real-time image processing. But the performance of these imagers depends on the quality and homogeneity of acousto-optic materials. In addition for many systems requirements are so demanding that crystals up to sizes of 10 cm length are desired. We have studied several selenides and halide crystals for laser and AO imagers for MWIR and LWIR wavelength regions. We have grown and fabricated crystals of

  7. STUDY ON THE CATIONIC POLYMERIZATION OF 1,3-PENTADIENE INITIATED BY AlCl3/ALKYL HALIDE SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    PENG Yuxing; LIU Jialin; DAI Hansong; CUN Linfeng

    1996-01-01

    The cationic polymerizations of 1, 3-pentadiene were initiated by AlCl3 in n-hexane at 30℃ in the presence of alkyl halides, i.e., tert-butyl chloride, tert-butyl bromide and isobutyl chloride. The effects of these halides on the polymer yield, molecular weight,crosslinking reaction, cyclization and polymer microstructure, have been investigated. Two main side reactions, crosslinking and cyclization, were suppressed and reduced by the addition of the halides. The proportion of 1, 4 units of polymer chains was increased by the presence of the halides, which reduced the polymer yield and the molecular weight of polymers.

  8. Photophysics of Hybrid Lead Halide Perovskites: The Role of Microstructure.

    Science.gov (United States)

    Srimath Kandada, Ajay Ram; Petrozza, Annamaria

    2016-03-15

    Since the first reports on high efficiency, solution processed solar cells based on hybrid lead halide perovskites, there has been an explosion of activities on these materials. Researchers with interests spanning the full range from conventional inorganic to emerging organic and hybrid optoelectronic technologies have been contributing to the prolific research output. This has led to solar cell power conversion efficiencies now exceeding 20% and the demonstration of proofs of concept for electroluminescent and lasing devices. Hybrid perovskites can be self-assembled by a simple chemical deposition of the constituent units, with the possibility of integrating the useful properties of organic and inorganic compounds at the molecular scale within a single crystalline material, thus enabling a fine-tuning of the electronic properties. Tellingly, the fundamental properties of these materials may make us think of a new, solution processable, GaAs-like semiconductor. While this can be true to a first approximation, hybrid perovskites are intrinsically complex materials, where the presence of various types of interactions and structural disorder may strongly affect their properties. In particular, a clear understanding and control of the relative interactions between the organic and inorganic moieties is of paramount importance to properly disentangle their innate physics. In this Account we review our recent studies which aim to clarify the relationship between structural and electronic properties from a molecular to mesoscopic level. First we identify the markers for local disorder at the molecular level by using Raman spectroscopy as a probe. Then, we exploit such a tool to explore the role of microstructure on the absorption and luminescence properties of the semiconductor. Finally we address the controversy surrounding electron-hole interactions and excitonic effects. We show that in hybrid lead-halide perovskites dielectric screening also depends on the local

  9. Effects of isoelectronic and halide surfactants on compound semiconductors

    Science.gov (United States)

    Howard, Alexander David

    Isoelectronic surfactants Sb, Bi, and N, have proven to increase the doping efficiency of Zn while concurrently reducing the unintentional impurities C, Si, and S in GaP. Additionally, surfactant Sb and N have demonstrated that altering the incorporation efficiency in GaP is also possible with a surfactant surface coverage of less than one. Halide surfactants Br and Cl were shown to systematically destroy ordering in GaInP. Furthermore, a distinct correlation between increasing surfactant Br or Cl in the vapor and surface roughness was evident. This work is presented in three main sections. First, surfactants Sb and Bi, from the pyrolysis of TMSb and TMBi, were examined to determine the effect on Zn doping in GaP. The data demonstrate that the incorporation of Zn can be increased by an order of magnitude in GaP to a value of approximately 1020 cm-3, the highest value reported to date. Additionally, these same surfactants lead to significant decreases in carbon contamination during growth. At high growth temperatures, the reduction can be as large as 100 x in GaP. Second, the role of steps versus the singular surface between steps was studied by using a surfactant fractional surface coverage of less than one. When surfactant Sb was used, the Zn concentration was increased and C was reduced. However, there was no discernable change in incorporation efficiency over the entire range of surfactant Sb studied. Interestingly, surfactant N showed a linear increase in the Zn doping the with amount of surfactant present during growth resulting in an increase of 2 x at the highest flow rate used. Third, halide surfactants Br and Cl, carbon-tetrabromide and carbon-tetrachloride, were studied for their effects on ordering in GaInP. Bromine systematically decreased the amount of CuPt ordering observed by photoluminescence and transmission electron microscopy. Both surfactants Br and Cl were shown to significantly increase the surface roughness, which is postulated to be the

  10. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  11. Silver nanoparticles from silver halide photography to plasmonics

    CERN Document Server

    Tani, Tadaaki

    2015-01-01

    This book provides systematic knowledge and ideas on nanoparticles of Ag and related materials. While Ag and metal nanoparticles are essential for plasmonics, silver halide (AgX) photography relies to a great extent on nanoparticles of Ag and AgX which have the same crystal structure and have been studied extensively for many years. This book has been written to combine the knowledge of nanoparticles of Ag and related materials in plasmonics and AgX photography in order to provide new ideas for metal nanoparticles in plasmonics. Chapters 1–3 of this book describe the structure and formation of nanoparticles of Ag and related materials. Systematic descriptions of the structure and preparation of Ag, Au, and noble-metal nanoparticles for plasmonics are followed by and related to those of nanoparticles of Ag and AgX in AgX photography. Knowledge of the structure and preparation of Ag and AgX nanoparticles in photography covers nanoparticles with widely varying sizes, shapes, and structures, and formation proce...

  12. Superconducting state in bromium halide at high pressure

    Science.gov (United States)

    Szczȩśniak, R.; Zemła, T. P.; Szczȩśniak, D.

    2016-08-01

    The thermodynamic properties of the superconducting state in bromium halide (HBr) compound have been analyzed in the framework of the Eliashberg formalism. In particular, for the range of the pressure (p) from 140 GPa to 200 GPa, it has been shown that the critical temperature increases significantly: TC(p) ∈ K, whereas the Coulomb pseudopotential (μ⋆) is equal to 0.1. Together with the increase of p, the values of the thermodynamic parameters such as: the ratio of the energy gap at the temperature of zero Kelvin to the critical temperature (RΔ ≡ 2 Δ (0) /kB TC), the ratio of the specific heat jump at the critical temperature to the electronic specific heat of the normal state (RC ≡ ΔC (TC) /CN (TC)), and the ratio related to the thermodynamic critical field (RH ≡TC CN (TC) / HC2 (0)) increasingly deviate from the predictions of the BCS model: RΔ(p) ∈ , RC(p) ∈ , and RH(p) ∈ . It should be noted that the increase of μ⋆ visibly lowers TC and significantly reduces the difference between the results of the Eliashberg and BCS theory.

  13. Electron–phonon coupling in hybrid lead halide perovskites

    Science.gov (United States)

    Wright, Adam D.; Verdi, Carla; Milot, Rebecca L.; Eperon, Giles E.; Pérez-Osorio, Miguel A.; Snaith, Henry J.; Giustino, Feliciano; Johnston, Michael B.; Herz, Laura M.

    2016-01-01

    Phonon scattering limits charge-carrier mobilities and governs emission line broadening in hybrid metal halide perovskites. Establishing how charge carriers interact with phonons in these materials is therefore essential for the development of high-efficiency perovskite photovoltaics and low-cost lasers. Here we investigate the temperature dependence of emission line broadening in the four commonly studied formamidinium and methylammonium perovskites, HC(NH2)2PbI3, HC(NH2)2PbBr3, CH3NH3PbI3 and CH3NH3PbBr3, and discover that scattering from longitudinal optical phonons via the Fröhlich interaction is the dominant source of electron–phonon coupling near room temperature, with scattering off acoustic phonons negligible. We determine energies for the interacting longitudinal optical phonon modes to be 11.5 and 15.3 meV, and Fröhlich coupling constants of ∼40 and 60 meV for the lead iodide and bromide perovskites, respectively. Our findings correlate well with first-principles calculations based on many-body perturbation theory, which underlines the suitability of an electronic band-structure picture for describing charge carriers in hybrid perovskites. PMID:27225329

  14. Two dimensional condensation of argon adsorbed on lamellar halides

    International Nuclear Information System (INIS)

    Lamellar halides such as NiCl2, FeCl2, NiBr2, MnBr2, MgBr2, CdBr2, CoI2, FeI2, MnI2, CaI2 and PbI2 were sublimed in a rapid stream of dry nitrogen. The adsorption of argon on such materials shows stepped isotherms which reveal two dimensional condensations. From sets of isotherms the Helmholtz free energy, the internal energy and the entropy of the successive layers are determined. From the entropy of the first layer the role of the potential relief of the adsorbent surface on the structure of the adsorbed layer may be determined while the Helmholtz free energy reveals how the ionic character of the adsorbent governs the attractive force of adsorption. The study of the second third and fourth layers shows that their growth follows quite a different behaviour depending on whether the Van der Waals diameter of argon is greater or smaller than the distance between adjacent anions on the crystal surface. A proposition is made to account for the difference in the critical temperatures of the first and second dense layers in terms of the vibrationnal state of their respective substrate. The occurence for the maximum critical temperature observed of corresponding to a triangular layer 3% more expanded than the (111) plane of solid argon is discussed

  15. Photography: enhancing sensitivity by silver-halide crystal doping

    International Nuclear Information System (INIS)

    The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield PHIeff of photoinduced silver cluster formation in silver halide microcrystals is usually much lower than the photoionization theoretical limit PHItheor=1 electron-hole pair per photon absorbed, owing to a subsequent very fast intra-crystal recombination of a part of the electron-hole pairs. In order to inhibit this recombination and favor the silver reduction by photo-electrons, the AgX crystals were doped with the formate HCO2- as a specific hole scavenger. First, the dopant scavenges the photoinduced hole, thus enhancing the electron escape from the pair recombination. Second, the CO2·- radical so formed transfers an electron to another silver cation, so that the PHIeff limit may be of 2Ag0 per photon. This Photoinduced Bielectronic Transfer mechanism is strictly proportional to the light quanta absorbed and induces an exceptional efficiency for enhancing the radio- or photographic sensitivity insofar as it totally suppresses the electron-hole recombination

  16. Photography: enhancing sensitivity by silver-halide crystal doping

    Energy Technology Data Exchange (ETDEWEB)

    Belloni, Jacqueline

    2003-06-01

    The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield PHI{sub eff} of photoinduced silver cluster formation in silver halide microcrystals is usually much lower than the photoionization theoretical limit PHI{sub theor}=1 electron-hole pair per photon absorbed, owing to a subsequent very fast intra-crystal recombination of a part of the electron-hole pairs. In order to inhibit this recombination and favor the silver reduction by photo-electrons, the AgX crystals were doped with the formate HCO{sub 2}{sup -} as a specific hole scavenger. First, the dopant scavenges the photoinduced hole, thus enhancing the electron escape from the pair recombination. Second, the CO{sub 2}{sup {center_dot}}{sup -} radical so formed transfers an electron to another silver cation, so that the PHI{sub eff} limit may be of 2Ag{sup 0} per photon. This Photoinduced Bielectronic Transfer mechanism is strictly proportional to the light quanta absorbed and induces an exceptional efficiency for enhancing the radio- or photographic sensitivity insofar as it totally suppresses the electron-hole recombination.

  17. Synthetic and structural chemistry of amidinate-substituted boron halides.

    Science.gov (United States)

    Hill, Nicholas J; Findlater, Michael; Cowley, Alan H

    2005-10-01

    The following new amidinate-substituted boron halides are reported: [PhC{N(SiMe(3))}(2)]BCl(2)(6), [MeC{NCy}(2)]BCl(2)(10), [Mes*C{NCy}(2)]BCl(2)(11), [MeC{N(i)Pr}(2)]BCl(2)(12), and [FcC{NCy}(2)]BBr(2)(13). Compound 6 was prepared via the trimethylsilyl chloride elimination reaction of BCl(3) with N,N,N'-tris(trimethylsilyl)benzamidine, and compounds 10-12 were prepared by salt metathesis between the lithium amidinates [RC(NR')(2)]Li and BX(3). Compound 13 was prepared via the insertion of 1,3-dicyclohexylcarbodiimide into the B-C bond of ferrocenyldibromoborane FcBBr(2). The molecular structures of 6, 10, 11, 13 and the known compound [PhC{N(SiMe(3))}(2)]BBr(2)(1) were established by single-crystal X-ray diffraction. PMID:16172649

  18. Infrared continuum radiation from metal halide high intensity discharge lamps

    Energy Technology Data Exchange (ETDEWEB)

    Herd, M T; Lawler, J E [Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2007-06-07

    Infrared (IR) continuum radiation from the arc of a metal halide high intensity discharge lamp was measured and modelled. There are three contributions to the near IR continuum from free electrons: electron-Hg atom bremsstrahlung, electron-ion bremsstrahlung and electron-ion recombination radiation. Electron-Hg atom bremsstrahlung is the most important of these. The radiation transport model utilized empirical Hg density, arc temperature and electron density maps. The line width of the Hg 7{sup 1}S{sub 0} to 6{sup 1}P{sub 1} resonance broadened transition was used to determine the arc core Hg density. The arc temperature as a function of radius was determined using the radiance of the Hg 9860, 7311 and 7166 cm{sup -1} lines. Relative densities of neutral Dy atoms and Dy ions as a function of radius were found using an Abel inversion of the relative line radiance of selected Dy I and Dy II lines. A Saha analysis was used to determine the electron density in the lamp. The continuum is 73% of the total near IR radiation in the 4000-12 800 cm{sup -1} range.

  19. Hysteresis, Stability, and Ion Migration in Lead Halide Perovskite Photovoltaics.

    Science.gov (United States)

    Miyano, Kenjiro; Yanagida, Masatoshi; Tripathi, Neeti; Shirai, Yasuhiro

    2016-06-16

    Ion migration has been suspected as the origin of various irreproducible and unstable properties, most notably the hysteresis, of lead halide perovskite photovoltaic (PV) cells since the early stage of the research. Although many evidence of ionic movement have been presented both numerically and experimentally, a coherent and quantitative picture that accounts for the observed irreproducible phenomena is still lacking. At the same time, however, it has been noticed that in certain types of PV cells, the hysteresis is absent or at least within the measurement reproducibility. We have previously shown that the electronic properties of hysteresis-free cells are well represented in terms of the conventional inorganic semiconductors. The reproducibility of these measurements was confirmed typically within tens of minutes under the biasing field of -1 V to +1.5 V. In order to probe the effect of ionic motion in the hysteresis-free cells, we extended the time scale and the biasing rage in the electronic measurements, from which we conclude the following: (1) From various evidence, it appears that ion migration is inevitable. However, it does not cause detrimental effects to the PV operation. (2) We propose, based on the quantitative characterization, that the degradation is more likely due to the chemical change at the interfaces between the carrier selective layers and perovskite rather than the compositional change of the lead iodide perovskite bulk. Together, they give much hope in the use of the lead iodide perovskite in the use of actual application. PMID:27227427

  20. Molecular structure and thermodynamic properties of scandium halides

    International Nuclear Information System (INIS)

    Experimental data on molecular constants of mono-, di- and trihalides of scandium, as well as di-scandium hexahalides of the composition ScXn and Sc2X6 (X = F - I; n = 1 - 3), have been analyzed. Specific features of the compounds molecule structure are considered. The values of molecular constants have been evaluated by the methods of statistical thermodynamics and thermodynamic properties of all scandium halides mentioned in the temperature range of 100 - 6000 K and 298.15 - 1000 K respectively for scandium monohalides and for di-, tri-, hexahalides have been calculated. The values of thermodynamic functions Cp Deg, Φ Deg (T), H Deg (T) - H Deg (0) at 298.15 K published for the first time equal respectively for ScF: 32.734; 192.186; 222.232; 8.958; for ScCl: 45.782; 203.351; 237.356; 10.138; for ScBr: 49.449; 215.090; 252.783; 11.238; for ScI: 42.605; 227.517; 265.635; 12.259

  1. Cerium doped lanthanum halides: fast scintillators for medical imaging

    International Nuclear Information System (INIS)

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl3:Ce3+ and LaBr3:Ce3+).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  2. Imaging of hydrogen halides photochemistry on argon and ice nanoparticles

    International Nuclear Information System (INIS)

    The photodissociation dynamics of HX (X = Cl, Br) molecules deposited on large ArN and (H2O)N, N¯≈ 102–103, clusters is investigated at 193 nm using velocity map imaging of H and Cl photofragments. In addition, time-of-flight mass spectrometry after electron ionization complemented by pickup cross section measurements provide information about the composition and structure of the clusters. The hydrogen halides coagulate efficiently to generate smaller (HX)n clusters on ArN upon multiple pickup conditions. This implies a high mobility of HX molecules on argon. On the other hand, the molecules remain isolated on (H2O)N. The photodissociation on ArN leads to strong H-fragment caging manifested by the fragment intensity peaking sharply at zero kinetic energy. Some of the Cl-fragments from HCl photodissociation on ArN are also caged, while some of the fragments escape the cluster directly without losing their kinetic energy. The images of H-fragments from HX on (H2O)N also exhibit a strong central intensity, however, with a different kinetic energy distribution which originates from different processes: the HX acidic dissociation followed by H3O neutral hydronium radical formation after the UV excitation, and the slow H-fragments stem from subsequent decay of the H3O. The corresponding Cl-cofragment from the photoexcitation of the HCl·(H2O)N is trapped in the ice nanoparticle

  3. Effects of halides on reaction of nucleosides with ozone.

    Science.gov (United States)

    Suzuki, Toshinori; Kaya, Eriko; Inukai, Michiyo

    2012-01-01

    Ozone (O(3)), a major component of photochemical oxidants, is used recently as a deodorizer in living spaces. It has been reported that O(3) can directly react with DNA, causing mutagenesis in human cells and carcinogenesis in mice. However, little is known about the effects of coexistent ions in the reaction of O(3). In the present study, we analyzed the effects of halides on the reaction of O(3) with nucleosides using reversed-phase high-performance liquid chromatography with ultraviolet detection. When aqueous O(3) solution was added to a nucleoside mixture in potassium phosphate buffer (pH 7.3), the nucleosides were consumed with the following decreasing order of importance: dGuo > Thd > dCyd > dAdo. The effects of addition of fluoride and chloride in the system were slight. Bromide suppressed the reactions of dGuo, Thd, and dAdo but enhanced the reaction of dCyd. The major products were 5-hydroxy-2'-deoxycytidine, 5-bromo-2'-deoxycytidine, and 8-bromo-2'-deoxyguanosine. The time course and pH dependence of the product yield indicated formation of hypobromous acid as the reactive agent. Iodide suppressed all the reactions effectively. The results suggest that bromide may alter the mutation spectrum by O(3) in humans. PMID:22646086

  4. Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2016-08-01

    Full Text Available Inorganic-organic halide organometal perovskites have demonstrated very promising performance for opto-electronic applications, such as solar cells, light-emitting diodes, lasers, single-photon sources, etc. However, the little knowledge on the underlying photophysics, especially on a microscopic scale, hampers the further improvement of devices based on this material. In this communication, correlated conventional photoluminescence (PL characterization and wide-field PL imaging as a function of time are employed to investigate the spatially- and temporally-resolved PL in CH3NH3PbI3−xClx perovskite films. Along with a continuous increase of the PL intensity during light soaking, we also observe PL blinking or PL intermittency behavior in individual grains of these films. Combined with significant suppression of PL blinking in perovskite films coated with a phenyl-C61-butyric acid methyl ester (PCBM layer, it suggests that this PL intermittency is attributed to Auger recombination induced by photoionized defects/traps or mobile ions within grains. These defects/traps are detrimental for light conversion and can be effectively passivated by the PCBM layer. This finding paves the way to provide a guideline on the further improvement of perovskite opto-electronic devices.

  5. Phase holograms in silver halide emulsions without a bleaching step

    Science.gov (United States)

    Belendez, Augusto; Madrigal, Roque F.; Pascual, Inmaculada V.; Fimia, Antonio

    2000-03-01

    Phase holograms in holographic emulsions are usually obtained by two bath processes (developing and bleaching). In this work we present a one step method to reach phase holograms with silver-halide emulsions. Which is based on the variation of the conditions of the typical developing processes of amplitude holograms. For this, we have used the well-known chemical developer, AAC, which is composed by ascorbic acid as a developing agent and sodium carbonate anhydrous as accelerator. Agfa 8E75 HD and BB-640 plates were used to obtain these phase gratings, whose colors are between yellow and brown. In function of the parameters of this developing method the resulting diffraction efficiency and optical density of the diffraction gratings were studied. One of these parameters studied is the influence of the grain size. In the case of Agfa plates diffraction efficiency around 18% with density emulsion, whose grain is smaller than that of the Agfa, diffraction efficiency near 30% has been obtained. The resulting gratings were analyzed through X-ray spectroscopy showing the differences of the structure of the developed silver when amplitude and transmission gratings are obtained. The angular response of both (transmission and amplitude) gratings were studied, where minimal transmission is showed at the Braggs angle in phase holograms, whilst a maximal value is obtained in amplitude gratings.

  6. Alternative translocation of protons and halide ions by bacteriorhodopsin

    International Nuclear Information System (INIS)

    Bacteriorhodopsin (bR568) in purple membrane near pH 2 shifts its absorption maximum from 568 to 605 nm forming the blue protein bRacid605, which no longer transports protons and which shows no transient deprotonation of the Schiff base upon illumination. Continued acid titration with HCl or HBr but not H2SO4 restores the purple chromophore to yield bRHCl564 or bRHBr568. These acid purple forms also regain transmembrane charge transport, but no transient Schiff base deprotonation is observed. In contrast to bR568, no rate decrease of the bRacidpurple transport kinetics is detected in 2H2O; however, the transport rate decreases by a factor of ∼ 2 in bRHBr568 compared with bRHCl564. The data indicate that in the acid purple form bR transports the halide anions instead of protons. The authors present a testable model for the transport mechanism, which should also be applicable to halorhodopsin

  7. Electron-phonon coupling in hybrid lead halide perovskites.

    Science.gov (United States)

    Wright, Adam D; Verdi, Carla; Milot, Rebecca L; Eperon, Giles E; Pérez-Osorio, Miguel A; Snaith, Henry J; Giustino, Feliciano; Johnston, Michael B; Herz, Laura M

    2016-01-01

    Phonon scattering limits charge-carrier mobilities and governs emission line broadening in hybrid metal halide perovskites. Establishing how charge carriers interact with phonons in these materials is therefore essential for the development of high-efficiency perovskite photovoltaics and low-cost lasers. Here we investigate the temperature dependence of emission line broadening in the four commonly studied formamidinium and methylammonium perovskites, HC(NH2)2PbI3, HC(NH2)2PbBr3, CH3NH3PbI3 and CH3NH3PbBr3, and discover that scattering from longitudinal optical phonons via the Fröhlich interaction is the dominant source of electron-phonon coupling near room temperature, with scattering off acoustic phonons negligible. We determine energies for the interacting longitudinal optical phonon modes to be 11.5 and 15.3 meV, and Fröhlich coupling constants of ∼40 and 60 meV for the lead iodide and bromide perovskites, respectively. Our findings correlate well with first-principles calculations based on many-body perturbation theory, which underlines the suitability of an electronic band-structure picture for describing charge carriers in hybrid perovskites. PMID:27225329

  8. CALCIUM SOAP LUBRICANTS

    OpenAIRE

    Alaz, Izer; Tugce, Nefise; Devrim, Balköse

    2014-01-01

    The article studies the properties of calcium stearate (CaSt2) and lubricants produced on its basis. These lubricants were prepared using sodium stearate and calcium chloride by subsidence from aqueous solutions. The CaSt2 and the light fraction of crude oil were mixed together to obtain lubricating substances. The article shows that CaSt2 had the melting temperature of 142.8 C that is higher than the melting temperature of crude oil (128 C). The compositions of obtained lubricants were stu...

  9. CALCIUM-INDUCED SUPRAMOLECULAR STRUCTURES IN THE CALCIUM CASEINATE SYSTEM

    Science.gov (United States)

    The molecular details deciphering the spontaneous calcium-induced protein aggregation process in the calcium caseinate system remain obscure. Understanding this complex process could lead to potential new applications of this important food ingredient. In this work, we studied calcium-induced supra...

  10. A sensor for calcium uptake

    OpenAIRE

    Collins, Sean; Meyer, Tobias

    2010-01-01

    Mitochondria — the cell’s power plants — increase their energy production in response to calcium signals in the cytoplasm. A regulator of the elusive mitochondrial calcium channel has now been identified.

  11. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Trials Resources and Publications Children's Bone Health and Calcium: Condition Information Skip sharing on social media links ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  12. Effects of halide ions on photodegradation of sulfonamide antibiotics: Formation of halogenated intermediates.

    Science.gov (United States)

    Li, Yingjie; Qiao, Xianliang; Zhang, Ya-Nan; Zhou, Chengzhi; Xie, Huaijun; Chen, Jingwen

    2016-10-01

    The occurrence of sulfonamide antibiotics (SAs) in estuarine waters urges insights into their environmental fate for ecological risk assessment. Although many studies focused on the photochemical behavior of SAs, yet the effects of halide ions relevant to estuarine and marine environments on their photodegradation have been poorly understood. Here, we investigated the effects of halide ions on the photodegradation of SAs with sulfapyridine, sulfamethazine, and sulfamethoxazole as representative compounds. Results showed that halide ions did not significantly impact the photodegradation of sulfapyridine and sulfamethoxazole, while they significantly promoted the photodegradation of sulfamethazine. Further experiments found that ionic strength applied with NaClO4 significantly enhanced the photodegradation of the SAs, which was attributed to the decreased quenching rate constant of the triplet-excited SAs ((3)SA(∗)). Compared with ionic strength, specific Cl(-) effects retarded the photodegradation of the SAs. Our study found that triplet-excited sulfamethazine can oxidize halide ions to produce halogen radicals, subsequently leading to the halogenation of sulfamethazine, which was confirmed by the identification of both chlorinated and brominated intermediates. These results indicate that halide ions play an important role in the photochemical behavior of some SAs in estuarine waters and seawater. The occurrence of halogenation for certain organic pollutants can be predicted by comparing the oxidation potentials of triplet-excited contaminants with those of halogen radicals. Our findings are helpful in understanding the photochemical behavior and assessing the ecological risks of SAs and other organic pollutants in estuarine and marine environment. PMID:27393965

  13. Graphitic cage transformation by electron-beam-induced catalysis with alkali-halide nanocrystals

    Science.gov (United States)

    Fujita, Jun-ichi; Tachi, Masashi; Ito, Naoto; Murakami, Katsuhisa; Takeguchi, Masaki

    2016-05-01

    We found that alkali-halide nanocrystals, such as KCl and NaCl, have strong catalytic capability to form graphitic carbon cages from amorphous carbon shells under electron beam irradiation. In addition to the electron beam irradiation strongly inducing the decomposition of alkali-halide nanocrystals, graphene fragments were formed and linked together to form the final product of thin graphitic carbon cages after the evaporation of alkali-halide nanocrystals. The required electron dose was approximately 1 to 20 C/cm2 at 120 keV at room temperature, which was about two orders of magnitude smaller than that required for conventional beam-induced graphitization. The “knock-on” effect of primary electrons strongly induced the decomposition of the alkali-halide crystal inside the amorphous carbon shell. However, the strong ionic cohesion quickly reformed the crystal into thin layers inside the amorphous shell. The bond excitation induced by the electron beam irradiation seemed to enhance strongly the graphitization at the interface between the outer amorphous carbon shell and the inner alkali-halide crystal.

  14. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  15. Alkaline and alkaline earth metal phosphate halides and phosphors

    Science.gov (United States)

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  16. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about...

  17. Impregnating Coal With Calcium Carbonate

    Science.gov (United States)

    Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

    1991-01-01

    Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

  18. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine;

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and...... renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis....

  19. Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl3 promoted homocoupling

    OpenAIRE

    Aiichiro Nagaki; Yuki Uesugi; Yutaka Tomida; Jun-ichi Yoshida

    2011-01-01

    The use of FeCl3 resulted in a fast homocoupling of aryllithiums, and this enabled its integration with the halogen–lithium exchange reaction of aryl halides in a flow microreactor. This system allows the homocoupling of two aryl halides bearing electrophilic functional groups, such as CN and NO2, in under a minute.

  20. Copper(I)-catalyzed carbon-halogen bond-selective boryl substitution of alkyl halides bearing terminal alkene moieties

    OpenAIRE

    Iwamoto, Hiroaki; Kubota, Koji; Yamamoto, Eiji; Ito, Hajime

    2015-01-01

    The selective boryl substitution of alkyl halides bearing terminal C=C double bonds has been achieved using a copper(I)/tricyclohexylphosphine or copper(I)/o-diphenylphosphinophenol catalyst. This reaction represents a useful complementary approach to conventional procedures for the hydroboration of C=C double bonds or the borylative cyclization of alkyl halides bearing terminal alkenes.

  1. Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl3 promoted homocoupling

    OpenAIRE

    Nagaki, Aiichiro; Uesugi, Yuki; Tomida, Yutaka; Yoshida, Jun-ichi

    2011-01-01

    The use of FeCl3 resulted in a fast homocoupling of aryllithiums, and this enabled its integration with the halogen–lithium exchange reaction of aryl halides in a flow microreactor. This system allows the homocoupling of two aryl halides bearing electrophilic functional groups, such as CN and NO2, in under a minute.

  2. 10 CFR 431.324 - Uniform test method for the measurement of energy efficiency of metal halide ballasts.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Uniform test method for the measurement of energy efficiency of metal halide ballasts. 431.324 Section 431.324 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Metal Halide Lamp Ballasts...

  3. Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl3 promoted homocoupling

    Directory of Open Access Journals (Sweden)

    Aiichiro Nagaki

    2011-08-01

    Full Text Available The use of FeCl3 resulted in a fast homocoupling of aryllithiums, and this enabled its integration with the halogen–lithium exchange reaction of aryl halides in a flow microreactor. This system allows the homocoupling of two aryl halides bearing electrophilic functional groups, such as CN and NO2, in under a minute.

  4. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai, E-mail: lujian@fudan.edu.cn, E-mail: zhanghai@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Cao, Runan; Xu, Fei [Department of Physics, Shanghai University, Shanghai 200444 (China); Da, Peimei; Zheng, Gengfeng [Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai 200433 (China); Lu, Jian, E-mail: lujian@fudan.edu.cn, E-mail: zhanghai@fudan.edu.cn [State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China)

    2016-01-11

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources.

  5. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    International Nuclear Information System (INIS)

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources

  6. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    Energy Technology Data Exchange (ETDEWEB)

    Ding Yuan, Paul Guss, and Sanjoy Mukhopadhyay

    2009-04-01

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector’s self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  7. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    International Nuclear Information System (INIS)

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector's self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  8. Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J.;

    2014-01-01

    electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) – almost 27000 combinations, and have identified novel mixtures, with significantly improved storage......Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat to be...... supplied, making the total efficiency lower. Here, we apply density functional theory (DFT) calculations to predict new mixed metal halide ammines with improved storage capacities and the ability to release the stored ammonia in one step, at temperatures suitable for system integration with polymer...

  9. Lamp-Ballast Compatibility Index for Efficient Ceramic Metal Halide Lamp Operation

    Directory of Open Access Journals (Sweden)

    Sourish Chatterjee

    2013-11-01

    Full Text Available Development of energy efficient products and exploration of energy saving potential are major challenges for present day’s technology. Ceramic Metal Halide lamp is the latest improved version of metal halide lamp that finds its wide applications in indoor commercial lighting especially in retail shop lighting. This lamp shows better performance in terms of higher lumen per watt and colour constancy in comparison to conventional metal halide lamp. The inherent negative incremental impedance of CMH lamp demands the use of current control device in the lamp circuit and perfect matching of lamp ballast combination is required for efficient lamp operation. The electrical and photometric performance of two sets of commercial 70 watt CMH lamp and intregated ballast units were measured to investigate their compatibility for optimum lamp operation. The measured data were utilized to develop an electrical model for lamp ballast combination. Using this model a compatibility index is proposed which can be used for assessment of lamp performance.

  10. Effects of halides on plasmid-mediated silver resistance in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, A.; Maynes, M.; Silver, S. [Univ. of Illinois, Chicago, IL (United States). Dept. of Microbiology and Immunology

    1998-12-01

    Silver resistance of sensitive Escherichia coli J53 and resistance plasmid-containing J53(pMG101) was affected by halides in the growth medium. The effects of halides on Ag{sup +} resistance were measured with AgNO{sub 3} and silver sulfadiazine, both on agar and in liquid. Low concentrations of chloride made the differences in MICs between sensitive and resistant strains larger. High concentrations of halides increased the sensitivities of both strains to Ag{sup +}. The purpose of this report is to set out easy-to-use conditions for measuring silver sensitivity and resistance in familiar and widely used media, Luria-Bertani (LB) agar and broth, so as to facilitate wider identification of silver resistance in nature.

  11. Studies on radiation-sensitive nonsilver halide materials, (1)

    International Nuclear Information System (INIS)

    In order to discover new radiation-sensitive nonsilver halide materials, the coloration based on the formation of Stenhouse salts was studied in the following three systems: (a) furfural-amine/HCl aq/methanol solution, (b) furfural-amine/polyhalogenide/PMMA matrix, (c) furfural-amine/PVC matrix. Firstly, forty-five aromatic amines were surveyed to find out the amines suitable for the color precursors (reactant from furfural and amine) in the system (a). As a result, the five amines, which gave the precursors in good yields by the reaction with furfural, were selected: m-nitroaniline, N-methylaniline, m-methyl-N-methylaniline, aniline, and o-methoxyaniline. Secondly, the coloration induced by electron beam bombardment was studied in the systems (b) and (c) containing the color precursors (the reactants from these amines and furfural). Although the PMMA films containing the color precursors and polyhalogenides were sensitive to electron beam, they were not stable when standing under daylight at room temperature. The PVC films containing the color precursors were very stable and colored to reddish yellow (lambda sub(max) 498 - 545 nm) by electron beam bombardment. The PVC film containing N-methylaniline-furfural was the most sensitive and the increase in absorbance at 498 nm was 0.78 by electron beam bombardment of 60 kV - 7.5 x 10-7C/cm2. A good linear relationship existed between the degree of coloration and the amounts of electron beam bombardment in the range from 0 to 10-6C/cm2. (author)

  12. Imaging of hydrogen halides photochemistry on argon and ice nanoparticles.

    Science.gov (United States)

    Poterya, V; Lengyel, J; Pysanenko, A; Svrčková, P; Fárník, M

    2014-08-21

    The photodissociation dynamics of HX (X = Cl, Br) molecules deposited on large ArN and (H2O)N, N̄ ≈ 10(2)-10(3), clusters is investigated at 193 nm using velocity map imaging of H and Cl photofragments. In addition, time-of-flight mass spectrometry after electron ionization complemented by pickup cross section measurements provide information about the composition and structure of the clusters. The hydrogen halides coagulate efficiently to generate smaller (HX)n clusters on ArN upon multiple pickup conditions. This implies a high mobility of HX molecules on argon. On the other hand, the molecules remain isolated on (H2O)N. The photodissociation on ArN leads to strong H-fragment caging manifested by the fragment intensity peaking sharply at zero kinetic energy. Some of the Cl-fragments from HCl photodissociation on ArN are also caged, while some of the fragments escape the cluster directly without losing their kinetic energy. The images of H-fragments from HX on (H2O)N also exhibit a strong central intensity, however, with a different kinetic energy distribution which originates from different processes: the HX acidic dissociation followed by H3O neutral hydronium radical formation after the UV excitation, and the slow H-fragments stem from subsequent decay of the H3O. The corresponding Cl-cofragment from the photoexcitation of the HCl·(H2O)N is trapped in the ice nanoparticle. PMID:25149788

  13. Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides

    International Nuclear Information System (INIS)

    We have studied a reaction between the reduced form of titanocene dichloride (Cp2TiCl2) and a group of organic halides: benzyl derivatives (4-X-C6H4CH2Cl, X = H, NO2, CH3; 4-X-C6H4CH2Br, X = H, NO2, PhC(O); 4-X-C6H4CH2SCN, X = H, NO2) as well as three aryl halides (4-NO2C6H4Hal, Hal = Cl, Br; 4-CH3O-C6H4Cl). It has been shown that the electrochemical reduction of Cp2TiCl2 in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic C-Hal bond cleavage. The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers

  14. Research Update: Physical and electrical characteristics of lead halide perovskites for solar cell applications

    Directory of Open Access Journals (Sweden)

    Simon A. Bretschneider

    2014-04-01

    Full Text Available The field of thin-film photovoltaics has been recently enriched by the introduction of lead halide perovskites as absorber materials, which allow low-cost synthesis of solar cells with efficiencies exceeding 16%. The exact impact of the perovskite crystal structure and composition on the optoelectronic properties of the material are not fully understood. Our progress report highlights the knowledge gained about lead halide perovskites with a focus on physical and optoelectronic properties. We discuss the crystal and band structure of perovskite materials currently implemented in solar cells and the impact of the crystal properties on ferroelectricity, ambipolarity, and the properties of excitons.

  15. A mild and efficient procedure for the synthesis of ethers from various alkyl halides

    Directory of Open Access Journals (Sweden)

    Mosstafa Kazemi

    2013-10-01

    Full Text Available A simple, mild and practical procedure has been developed for the synthesis of symmetrical and unsymmetrical ethers by using DMSO, TBAI in the presence of K2CO3. We extended the utility of Potassium carbonate as an efficient base for the preparation of ethers. A wide range of alkyl aryl and dialkyl ethers are synthezied from treatment of aliphatic alcohols and phenols with various alkyl halides in the prescence of efficient base Potassium carbonate. Secondary alkyl halides were easily converted to corresponding ethers in releatively good yields . This is a mild, simple and practical procedure for the preparation of ethers in high yields and suitable times under mild condition.

  16. The electronic structure of the F-center in alkali-halides-The Bethe cluster - lattice

    International Nuclear Information System (INIS)

    The electronic structure of the F-center in alkali-halides with the NaCl structure has been studied using the Bethe Cluster lattice method. The central cluster has been taken as constituted by the vacancy and the nearest- and second-neighbors to it, respectively cations and anions. The optical transitions have been calculated and compared to experimental data on the location of the peak of the F-absorption band. The agreement obtained indicates that this method may be used to study properties of this defect in alkali halides. (Author)

  17. Mid-infrared planar silver halide waveguides with integrated grating couplers.

    Science.gov (United States)

    Schädle, Thomas; Eifert, Alexander; Kranz, Christine; Raichlin, Yosef; Katzir, Abraham; Mizaikoff, Boris

    2013-09-01

    Grating couplers for planar silver halide waveguides were designed and fabricated by using focused ion beam (FIB) milling technology, facilitating coupling of mid-infrared radiation from quantum cascade lasers into thin-film waveguide structures. An optimized rectangular grating structure for an emitted wavelength of 10.4 μm, with a grating constant of 16.4 μm was integrated into a silver halide waveguide substrate via an optimized FIB fabrication procedure. Efficient incoupling and radiation propagation through the waveguide was confirmed by analyzing droplets of acetic acid at different concentrations, deposited at the waveguide surface via evanescent field absorption spectroscopy. PMID:24067637

  18. Propensity of heavier halides for the water/vapor interface revisited using the Amoeba force field

    Science.gov (United States)

    Tůma, Lukáš; Jeníček, Dominik; Jungwirth, Pavel

    2005-08-01

    Molecular dynamics simulations of aqueous sodium halide solutions in slab geometry were performed using the state-of-the-art polarizable Amoeba force field. The present calculations reveal a propensity of halide anions for the water/vapor interface, which correlates with the ionic size and polarizability and, therefore, increases in the series Cl - < Br - < I -. These results are in a quantitative agreement with previous calculations employing much simpler polarizable potentials and are supported by a mounting experimental evidence from photoelectron and non-linear optical and vibrational spectroscopies.

  19. Surface tension of molten alkali metal halides as a function of ion sizes

    International Nuclear Information System (INIS)

    The analysis of the experimental data on the surface tension of the liquid/vapor interphase boundary of the molten alkali metal halides MX (M Li-Cs, X = F-I) near the melting temperature, accounting for the cation and anion dimensional differences, is presented. The main attention is focused at the manifestation of the effects of the interphase boundary of the effects of the interphase boundary thickness and twofold electric layer. It is shown, that the experimental data on the whole MX series may be represented in the form of the electrocapillary curve on the graph of the surface tension dependence on the degree of the halides dimensional asymmetry

  20. High-Efficiency Flexible Solar Cells Based on Organometal Halide Perovskites.

    Science.gov (United States)

    Wang, Yuming; Bai, Sai; Cheng, Lu; Wang, Nana; Wang, Jianpu; Gao, Feng; Huang, Wei

    2016-06-01

    Flexible and light-weight solar cells are important because they not only supply power to wearable and portable devices, but also reduce the transportation and installation cost of solar panels. High-efficiency organometal halide perovskite solar cells can be fabricated by a low-temperature solution process, and hence are promising for flexible-solar-cell applications. Here, the development of perovskite solar cells is briefly discussed, followed by the merits of organometal halide perovskites as promising candidates as high-efficiency, flexible, and light-weight photovoltaic materials. Afterward, recent developments of flexible solar cells based on perovskites are reviewed. PMID:26669326

  1. Nickel-catalyzed regiodivergent opening of epoxides with aryl halides: co-catalysis controls regioselectivity.

    Science.gov (United States)

    Zhao, Yang; Weix, Daniel J

    2014-01-01

    Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position, presumably via Ti(III)-mediated radical generation. 1,2-Disubstituted epoxides are opened under both conditions to form predominantly the trans product. PMID:24341892

  2. Nickel-catalyzed electrochemical couplings of vinyl halides: synthetic and stereochemical aspects

    Science.gov (United States)

    Cannes; Condon; Durandetti; Perichon; Nedelec

    2000-07-28

    Homo- and cross-coupling involving alkenyl halides have been performed efficiently using an electroassisted nickel-complex catalysis. Valuable product such as conjugated dienes, beta,gamma- or gamma,delta-unsaturated esters, ketones, or nitriles, as well as alkenylated aryl compounds are thus prepared with high yields and high stereoselectivity. Partial isomerization is only observed in a few cases, when the alkenyl halide is involved in a late step of the catalytic cycle. This is the case in the preparation of (Z,Z)-1,3-diene. PMID:10959862

  3. Fruit Calcium: Transport and Physiology

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D.; Burton, Rachel A.; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  4. Fruit Calcium: Transport and Physiology.

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D; Burton, Rachel A; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  5. Calcium and calcitonin responses to calcium infusion in type I diabetes mellitus.

    OpenAIRE

    Amado, J. A.; C. Gomez; Obaya, S.; Otero, M; Gonzalez-Macias, J

    1987-01-01

    We studied calcium and calcium and calcitonin responses to intravenous calcium infusion (3 mg of elemental calcium/kg of body weight in 10 minutes) in 21 type I diabetic males and 17 age-matched normal males. Baseline total calcium, parathyroid hormone and calcitonin levels were normal in the diabetic group, but ionized calcium was lowered. Cortical bone status and osteocalcin levels were normal, suggesting a normal osteoblastic function. Total calcium and ionized calcium responses to calcium...

  6. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  7. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  8. Reverse calcium affinity purification of Fab with calcium derivatized hydroxyapatite

    OpenAIRE

    Gagnon, Pete; Cheung, Chia-wei; Yazaki, Paul J.

    2009-01-01

    This study introduces the application of calcium-derivatized hydroxyapatite for purification of Fab. Fab binds to native hydroxyapatite but fails to bind to the calcium derivatized form. IgG, Fc, and most other protein contaminants bind to the calcium form. This supports Fab purification by a simple flow-through method that achieves greater than 95% purity from papain digests and mammalian cell culture supernatants. Alternatively, Fab can be concentrated on native hydroxyapatite then eluted s...

  9. GaN nanotubes grown by halide vapor phase epitaxy

    International Nuclear Information System (INIS)

    Full text: Wide-band gap GaN nanostructures such as quantum dots, nanorods, nanowires, nano columns and nanotubes have a strong potential within areas of biochemical sensing, nanofluidics, and optoelectronics. GaN nanotubes play a role of the building blocks for several applications such as solution-based transistors and highly sensitive nanotube molecular sensors. We have studied non-catalytic and Au-assisted growth of GaN nanotubes using halide vapor phase epitaxy (HVPE) technique. The growth was performed in the temperature range 480 degrees Celsius to 520 degrees Celsius using pure N2 as a carrier gas at atmospheric pressure. The nanotubes size, shape, density and the selectivity of growth have been studied depending on V/III ratio, growth temperature and substrate material. By increasing the GaCl partial pressure, the structure changed from dot-like to nanotubes. The nanotubes were about 1 μm long with a diameter of typically 200 nm. In addition, it was observed that the nanostructures were spontaneously nucleated at droplets of Ga or, when using Au-coated Al2O3, on droplets of Au/Ga alloy. By varying the growth temperature, the inner diameter of the nanotubes could be controlled. A growth model is suggested, where the nanotubes are nucleated at droplets of Ga or an Au/Ga alloy. Our experimental results suggest that the approach with pre-patterned Au-coated Al2O3 substrates has the potential for fabrication of well-organized nanotubes with a high density. Nanostructures were characterized using electron microscopy methods and by low temperature time-resolved photoluminescence (TRPL). Studies were performed on samples with different wall thickness in the range of 35-75 nm. Two recombination processes with different dynamics contribute to the emission spectra of the GaN nanotubes. The photoluminescence peak shifts rapidly to the higher energy from 3.47 eV to 3.75 eV within a very short time of 30 ps. The origin of the emission having a short lifetime is related

  10. Glycochenodeoxycholic acid inhibits calcium phosphate precipitation in vitro by preventing the transformation of amorphous calcium phosphate to calcium hydroxyapatite.

    OpenAIRE

    Qiu, S M; Wen, G.; Hirakawa, N; Soloway, R D; Hong, N K; Crowther, R S

    1991-01-01

    Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxycholic acid inhibits calcium hydroxyapatite formation. Glycochenodeoxycholic acid (2 mM) totally inhibited transformation of amorphous calcium phosphate microprecipitates to macroscopic crystalline...

  11. Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

    OpenAIRE

    Han Wang; Kun Wen; Nurbiya Nurahmat; Yan Shao; He Zhang; Chao Wei; Ya Li; Yongjia Shen; Zhihua Sun

    2012-01-01

    By using ionic liquids as solvents, the chlorination or bromination of unprotected anilines at the para-position can be achieved in high yields with copper halides under mild conditions, without the need for potentially hazardous operations such as supplementing oxygen or gaseous HCl.

  12. A study on the electrochemical behaviour of polypyrrole films in concentrated aqueous alkali halide electrolytes

    DEFF Research Database (Denmark)

    Jafeen, M. J. M.; Careem, M.A.; Skaarup, Steen

    2014-01-01

    difference. In highly concentrated aqueous electrolytes, the mass of the PPy/DBS film at the end of each redox cycle is found to drift, which can be controlled by changing the concentration of the electrolyte. The PPy/DBS films were also cycled at different scan rates in various alkali halide aqueous...

  13. α-Regioselective Barbier Reaction of Carbonyl Compounds and Allyl Halides Mediated by Praseodymium.

    Science.gov (United States)

    Wu, San; Li, Ying; Zhang, Songlin

    2016-09-01

    The first utility of praseodymium as a mediating metal in the Barbier reaction of carbonyl compounds with allyl halides was reported in this paper. In contrast to the traditional metal-mediated or catalyzed Barbier reactions, exclusive α-adducts were obtained in this one-pot reaction with a broad scope of substrates and feasible reaction conditions. PMID:27490708

  14. Magnetic Silica Supported Copper: A Modular Approach to Aqueous Ullmann-type Amination of Aryl Halides

    Science.gov (United States)

    One-pot synthesis of magnetic silica supported copper catalyst has been described via in situ generated magnetic silica (Fe3O4@SiO2); the catalyst can be used for the efficacious amination of aryl halides in aqueous medium under microwave irradiation.

  15. Concentration dependence of halide fluxes and selectivity of the anion pathway in toad skin

    DEFF Research Database (Denmark)

    Harck, A F; Larsen, Erik Hviid

    1986-01-01

    mV (apical bath negative). The active sodium currents were eliminated by replacing external Na+ with K+. With [Cl-]o varying between 1.45 mM and 110 mM (gluconate substitution) and [I-]o = 3 mM, the total clamping current (y) and the sum of halide currents (x), estimated from flux measurements, were...

  16. Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

    Directory of Open Access Journals (Sweden)

    Han Wang

    2012-05-01

    Full Text Available By using ionic liquids as solvents, the chlorination or bromination of unprotected anilines at the para-position can be achieved in high yields with copper halides under mild conditions, without the need for potentially hazardous operations such as supplementing oxygen or gaseous HCl.

  17. Amination of Aryl Halides and Esters Using Intensified Continuous Flow Processing

    OpenAIRE

    Thomas M. Kohl; Christian H. Hornung; John Tsanaktsidis

    2015-01-01

    Significant process intensification of the amination reactions of aryl halides and esters has been demonstrated using continuous flow processing. Using this technology traditionally difficult amination reactions have been performed safely at elevated temperatures. These reactions were successfully conducted on laboratory scale coil reactor modules with 1 mm internal diameter (ID) and on a preparatory scale tubular reactor with 6 mm ID containing static mixers.

  18. Iron-Catalyzed Acylation of Polyfunctionalized Aryl- and Benzylzinc Halides with Acid Chlorides.

    Science.gov (United States)

    Benischke, Andreas D; Leroux, Marcel; Knoll, Irina; Knochel, Paul

    2016-08-01

    FeCl2 (5 mol %) catalyzes a smooth and convenient acylation of functionalized arylzinc halides at 50 °C (2-4 h) and benzylic zinc chlorides at 25 °C (0.5-4 h) with a variety of acid chlorides leading to polyfunctionalized diaryl and aryl heteroaryl ketones. PMID:27457108

  19. Epitaxial Growth of a Methoxy-Functionalized Quaterphenylene on Alkali Halide Surfaces

    DEFF Research Database (Denmark)

    Balzer, Frank; Sun, Rong; Parisi, Jürgen;

    2015-01-01

    The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of lowenergy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X...

  20. Enhancement of Exciton Emission in Lead Halide-Based Layered Perovskites by Cation Mixing.

    Science.gov (United States)

    Era, Masanao; Komatsu, Yumeko; Sakamoto, Naotaka

    2016-04-01

    Spin-coated films of a lead halide, PbX: X = I and Br, layered perovskites having cyclohexenylethyl ammonium molecule as an organic layer, which were mixed with other metal halide-based layered perovskites consisting of various divalent metal halides (for example, Ca2, Cdl2, FeI2, SnBr2 and so on), were prepared. The results of X-ray diffraction measurements exhibited that solid solution formation between PbX-based layered perovskite and other divalent metal halide-based layered perovskites was observed up to very high molar concentration of 50 molar% in the mixed film samples when divalent cations having ionic radius close to that of Pb2+ were employed. In the solid solution films, the exciton emission was much enhanced at room temperature. Exciton emission intensity of Pbl-based layered perovskite mixed with Cal-based layered perovskite (20 molar%) is about 5 times large that of the pristine Pbl-based layered perovskite, and that of PbBr-based layered perovskite mixed with SnBr-based layered perovskite (20 molar%) was also about 5 times large that of the pristine PbBr-based layered perovskite at room temperature. PMID:27451628

  1. Chemistry of gaseous lower-valent actinide halides. Technical progress report

    International Nuclear Information System (INIS)

    Objective is to provide thermochemical data for key actinide halide and oxyhalide systems. Progress is reported on bond dissociation energies of gaseous ThCl4, ThCl3, ThCl2, and ThCl; bond dissociation energies of ruthenium fluorides; and mass spectroscopy of UF6

  2. New Condensation Reaction of β-keto-δ-valerolactones, Carbon Disulfide and Alkyl Halides

    Institute of Scientific and Technical Information of China (English)

    You Ming WANG; Yu Xin LI; Su Hua WANG; Zheng Ming LI

    2004-01-01

    β-Keto-δ-valerolactones, which were obtained by reaction of acetoacetate with aldehydes or ketones, reacted with carbon disulfide, alkyl halides and a new condensation reaction was developed. The structures of the products 3 were confirmed by 1HNMR spectra and elemental analysis.

  3. Synthesis of Cyclic Carbonates from CO2 and Epoxides Catalyzed by Hexaalkylguanidinium Halides

    Institute of Scientific and Technical Information of China (English)

    DUAN Hai-feng; LI Sheng-hai; LIN Ying-jie; XIE Hai-bo; ZHANG Suo-bo; WANG Zong-mu

    2004-01-01

    Hexaalkylguanidinium halides exhibit an efficient catalytic activity in the synthesis of cyclic carbonates from epoxides and carbon dioxide. By this method cyclic carbonates can be obtained in a high yield and a high selectivity at a low temperature and atmospheric pressure. This procedure is easy for the product isolation and recycling of the catalyst.

  4. Palladium-catalyzed Coupling between Aryl Halides and Trimethylsilylacetylene Assisted by Dimethylaminotrimethyltin

    Institute of Scientific and Technical Information of China (English)

    Cai Liangzhen; Yang Dujuan; Sun Zhonghua; Tao Xiaochun; Cai Lisheng; Pike Victor W

    2011-01-01

    Palladium-catalyzed coupling between aryl halides, especially less reactive ones or N-heteroaryls, and trimethylsilylacetylene in the presence of dimethylaminotrimethyltin generated the coupled products in high yields. The reaction does not need CuI and base as auxiliary agents.

  5. Luminescent decay and spectra of impurity-activated alkali halides under high pressure

    International Nuclear Information System (INIS)

    The effect of high pressure on the luminescence of alkali halides doped with the transition-metal ions Cu+ and Ag+ and the heavy-metal ions In+ and Tl+ was investigated to 140 kbar. Measurement of spectra allowed the prediction of kinetic properties, and the predictions agree with lifetime data

  6. An Improved Protocol for the Pd-catalyzed α-Arylation of Aldehydes with Aryl Halides

    OpenAIRE

    Martín, Rubén; Buchwald, Stephen L.

    2008-01-01

    An improved protocol for the Pd-catalyzed α-arylation of aldehydes with aryl halides has been developed. The new catalytic system allows for the coupling of an array of substrates including challenging electron-rich aryl bromides and less reactive aryl chlorides. The utility of this method has been demonstrated in a new total synthesis of (±)-sporochnol.

  7. Exciton Binding Energy in Organic-Inorganic Tri-Halide Perovskites.

    Science.gov (United States)

    Askar, Abdelrahman M; Shankar, Karthik

    2016-06-01

    The recent dramatic increase in the power conversion efficiencies of organic-inorganic tri-halide perovskite solar cells has triggered intense research worldwide and created a paradigm shift in the photovoltaics field. It is crucial to develop a solid understanding of the photophysical processes underlying solar cell operation in order to both further improve the photovoltaic performance of perovskite solar cells as well as to exploit the broader optoelectronic applications of the tri-halide perovskites. In this short review, we summarize the main research findings about the binding energy of excitons in tri-halide perovskite materials and find that a value in the range of 2-22 meV at room temperature would be a safe estimate. Spontaneous free carrier generation is the dominant process taking place directly after photoexcitation in organic-inorganic tri-halide perovskites at room temperature, which eliminates the exciton diffusion bottleneck present in organic solar cells and constitutes a major contributing factor to the high photovoltaic performance of this material. PMID:27427650

  8. Ionic liquids as solvent for efficient esterification of carboxylic acids with alkyl halides

    OpenAIRE

    carboxylic, Ionic liquids as solvent for efficient e

    2010-01-01

    The selective esterification of carboxylic acid derivatives with a variety of alkyl halides was carried out using ionic liquid as solvent in the presence of triethylamine. The reaction was found to proceed under relatively mild conditions with excellent conversions (up to 99%) and selectivities. The ionic liquid was recycled and reused.

  9. Correlated linear response calculations of the C6 dispersion coefficients of hydrogen halides

    Czech Academy of Sciences Publication Activity Database

    Sauer, S. P. A.; Paidarová, Ivana

    2007-01-01

    Roč. 3, 2-4 (2007), s. 399-421. ISSN 1574-0404 R&D Projects: GA AV ČR IAA401870702 Institutional research plan: CEZ:AV0Z40400503 Keywords : hydrogen halides * C6 dospersion coefficients * van der Waals coefficients * polarizability at imaginary frequences * SOPPA Subject RIV: CF - Physical ; Theoretical Chemistry

  10. Synthesis and Spectroscopic studies on cadmium halide complexes of isonicotinic acid

    International Nuclear Information System (INIS)

    In this study infrared spectra (4000-400cm-1) are reported for the cadmium(II) halide isonicotinic acid complexes. Vibrational assignments are given for all observed bands. Some structure spectra correlations and frequency shifts were found. It's found the frequency shifts depends on the halogen for a given metal. Certain chemical formulas were determined using elemental analysis results

  11. Direct ToF-SIMS analysis of organic halides and amines on TLC plates

    International Nuclear Information System (INIS)

    It has been reported that: 'direct analysis of thin layer chromatography (TLC) plates with secondary ion mass spectrometry (SIMS) yields no satisfactory results' (J. Chromatogr. A 1084 (2005) 113-118). While this statement appears to be true in general, we have identified two important classes of compounds, organic halides and amines, that appear to yield to such direct analyses. For example, five organic halides with diverse structures were eluted on normal phase TLC plates. In all cases the halide signals in the negative ion time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra were notably stronger than the background signals. Similarly, a series of five organic amines with diverse structures were directly analyzed by positive ion ToF-SIMS. In all but one of the spectra characteristic, and sometimes even quasi-molecular ions, were observed. Most likely, the good halide ion yields are largely a function of the electronegativity of the halogens. We also propose that direct analysis of amines on normal phase silica gel is facilitated by the acidity, i.e., proton donation, of surface silanol groups

  12. Homocoupling of benzyl halides catalyzed by POCOP-nickel pincer complexes

    KAUST Repository

    Chen, Tao

    2012-08-01

    Two types of POCOP-nickel(II) pincer complexes were prepared by mixing POCOP pincer ligands and NiX 2 in toluene at reflux. The resulting nickel complexes efficiently catalyze the homocoupling reactions of benzyl halides in the presence of zinc. The coupled products were obtained in excellent to quantitative yields. © 2012 Elsevier Ltd. All rights reserved.

  13. Viabilization of a new aluminium grain refiner based on Zirconium halide salt

    International Nuclear Information System (INIS)

    A new aluminium grain refiner based on Zirconium halide salt is proposed. Its efficiency, as grain refiner is analysed varying the salt amount, the inoculation temperature and holding time. The grain size reduction shows to be dependent on the salt amount and independent on the inoculation temperature. The holding time effects is dependent on the innoculated salt amount. (Author)

  14. Halocyclization of Unsaturated Guanidines Mediated by Koser's Reagent and Lithium Halides.

    Science.gov (United States)

    Daniel, Marion; Blanchard, Florent; Nocquet-Thibault, Sophie; Cariou, Kevin; Dodd, Robert H

    2015-11-01

    The synthesis of halogenated cyclic guanidines through iodine(III)-mediated umpolung of halide salts is described. Cyclic guanidines of various sizes can be obtained with generally excellent regioselectivities through either a chloro- or a bromocyclization, using Koser's reagent and the corresponding lithium salt. PMID:26492553

  15. Synthesis and structural characterization of a calcium coordination polymer based on a 3-bridging tetradentate binding mode of glycine

    Indian Academy of Sciences (India)

    Subramanian Natarajan; Bikshandarkoil R Srinivasan; J Kalyana Sundar; K Ravikumar; R V Krishnakumar; J Suresh

    2012-07-01

    A new coordination polymer namely [[Ca6(H-gly)12(H2O)18]Cl12·6H2O] (1) (H-gly = glycine) has been isolated from the calcium chloride-glycine-water system and structurally characterized. Each Ca(II) in 1 is eight-coordinated and is bonded to eight oxygen atoms three of which are from terminal water molecules and five oxygen atoms from four symmetry related zwitterionic glycine ligands. The H-gly ligands exhibit two different binding modes viz. a monodentate carboxylate ligation and a 3-tetradentate bridging carboxylate binding mode, which results in the formation of a one-dimensional coordination polymer. In the infinite chain the Ca(II) atoms are organized in a zigzag fashion. A comparative study reveals a rich and diverse structural chemistry of calcium halide-glycine compounds.

  16. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  17. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Moilanen, A.; Norby, P.; Papadakis, K.; Posselt, D.; Sørensen, L. H.

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...

  18. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  19. Effects of Alloying on the Optical Properties of Organic-Inorganic Lead Halide Perovskite Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Ndione, Paul F.; Li, Zhen; Zhu, Kai

    2016-09-07

    Complex refractive index and dielectric function spectra of organic-inorganic lead halide perovskite alloy thin films are presented, together with the critical-point parameter analysis (energy and broadening) of the respective composition. Thin films of methylammonium lead halide alloys (MAPbI3, MAPbBr3, MAPbBr2I, and MAPbBrI2), formamidinium lead halide alloys (FAPbI3, FAPbBr3, and FAPbBr2I), and formamidinium cesium lead halide alloys [FA0.85Cs0.15PbI3, FA0.85Cs0.15PbBrI2, and FA0.85Cs0.15Pb(Br0.4I0.6)3] were studied. The complex refractive index and dielectric functions were determined by spectroscopic ellipsometry (SE) in the photon energy range of 0.7-6.5 eV. Critical point energies and optical transitions were obtained by lineshape fitting to the second-derivative of the complex dielectric function data of these thin films as a function of alloy composition. Absorption onset in the vicinity of the bandgap, as well as critical point energies and optical band transition shift toward higher energies as the concentration of Br in the films increases. Cation alloying (Cs+) has less effect on the optical properties of the thin films compared to halide mixed alloys. The reported optical properties can help to understand the fundamental properties of the perovskite materials and also be used for optimizing or designing new devices.

  20. Vibrational spectra of discrete UO22+ halide complexes in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Groenewold; Michael J. van Stipdonk; Wibe A. de Jong; Jos Oomens; Garold L. Gresham

    2010-11-01

    The intrinsic binding of halide ions to the metal center in the uranyl molecule is a topic of ongoing research interest in both the actinide separations and theoretical communities. Investigations of structure in the condensed phases is frequently obfuscated by solvent interactions, that can alter ligand binding and spectroscopic properties. The approach taken in this study is to move the uranyl halide complexes into the gas phase where they are free from solvent interactions, and then interrogate their vibrational spectroscopy using infrared multiple photon dissociation (IRMPD). The spectra of cationic coordination complexes having the composition [UO2(X)(ACO)3]+ (X = F, Cl, Br and I; ACO = acetone) were acquired using electrospray for ion formation, and monitoring the ion signal from the photoelimination of ACO ligands. The studies showed that the asymmetric v3 UO2 frequency was insensitive to halide identity as X was varied from Cl to I, suggesting that in these pseudo octahedral complexes, changing the nucleophilicity of the halide did not appreciably alter the binding in the complex. The v3 peak in the spectrum of the F-containing complex was ~ 10 cm-1 lower indicating stronger coordination in this complex. Similarly the ACO carbonyl stretches showed that the C=O frequency was relatively insensitive to the identity of the halide, although a modest shift to the blue was seen for the complexes with the more nucleophilic anions, consistent with the idea that they loosen solvent binding. Surprisingly, the v1 stretch was activated when the softer anions Cl, Br and I were present in the complexes. IR studies of the anionic complexes were conducted by measuring the v3 UO2 frequencies of [UO2X3]-, where X = Cl-, Br- and I-. The trifluoro complex could not be photodissociated. In these negatively charged complexes, the UO2 v3 values decreased with increasing anion nucleophilicity. This observation was consistent with DFT calculations that indicated that dissociation

  1. 21 CFR 573.240 - Calcium periodate.

    Science.gov (United States)

    2010-04-01

    ... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used...

  2. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  3. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  4. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  5. Compartmentalization of the submembrane calcium activity during calcium influx and its significance in transmitter release.

    OpenAIRE

    Simon, S M; Llinás, R R

    1985-01-01

    Quantitative modeling indicates that, in presynaptic terminals, the intracellular calcium concentration profile during inward calcium current is characterized by discrete peaks of calcium immediately adjacent to the calcium channels. This restriction of intracellular calcium concentration suggests a remarkably well specified intracellular architecture such that calcium, as a second messenger, may regulate particular intracellular domains with a great degree of specificity.

  6. The ultraviolet photodissociation dynamics of the hydrogen halides

    International Nuclear Information System (INIS)

    The first electronic absorption bands of hydrogen halide (HX) molecules - HI, HBr, HCl and DCl - have been studied using two experimental, laser-based techniques. Each band of HX consists of absorption of ultraviolet (UV) radiation and leads to fragmentation into two sets of products: H(2S) + X(2Pj); j=3/2, 1/2. Numerous measurements that cover most of the UV absorption bands (λ∼200-300 nm) of HI and HBr were made using H Rydberg atom photofragment translational spectroscopy (HRPTS). The results comprise two important properties: the branching between the accessible product channels and the spatial distributions of the recoil velocities of the photofragments. These extensive observations afford a detailed interpretation of the featureless absorption bands in terms of the relative influences of transitions and dissociations involving multiple electronic states: 3Π(1), 3Π(0+), 1Π(1) and 3Σ+(1). The photolysis of HCl between 201 and 210 nm was also studied by HRPTS to provide a number of direct determinations of the relative product yield for comparison with the best available theoretical predictions based on ab initio electronic structure calculations and a time-independent treatment of the photodissociation dynamics. The good agreement between the calculations and observations provided encouraging support for the theoretical description. The second experimental method combined resonance enhanced multiphoton ionization (REMPI) and a time-of-flight mass spectrometer (TOF MS) to quantify the relative production of die spin-orbit components of the halogen photoproducts from HI, DCl and vibrationally-excited HCl. Relating the observed REMPI yields for each quantum state to the nascent populations required a scaling factor to account for the different ionization probabilities. This was derived for the ground state of the chlorine atom by comparing the Cl(2Pj) REMPI signal recorded following photolysis of HCl at λ=205.5 nm with a direct determination obtained by

  7. Molten lanthanide halide systems: experimental, modeling and thermodynamic computation

    International Nuclear Information System (INIS)

    Molten lanthanide halide based systems were studied using two approaches: experiments and calculations. Liquid mixing enthalpies of chloride europium systems (MCl-EuCl2; M = Na, K, Rb) were measured at 1138 K. They can be represented (in kJ.mol-1) as a function of the molar fraction of EuCl2 (x) with the polynomials: ΔmixHm0 (NaCl - EuCl2) = x(1 - x)(-1.6634 - 5.4964x + 6.3324x2), ΔmixHm0 (KCl - EuCl2 = x(1 - x)(-21.262 + 17.196x- 6.6293x2), ΔmixHm0 (RbCl - EuCl2 = x(1 - x)(-25.286 + 15.786x). The NaCl-EuCl2 phase diagram was experimentally determined. It exhibits an eutectic equilibrium (x(EuCl2) = 0.49; Teut = 847 ± 2 K). Temperatures and enthalpies effusion and transition of EuCl2 were also measured (Ttrs= 1014 ± 2 K, ΔtrsHm0 = 11.5 ± 0.7 kJ.mol1, TfUs = 1125 ± 2 K, ΔfusHm0 = 18.7 ± 1,1 kJ.mol-1) as well as heat capacities (Cpm0(EuCl2, ortho.) = 76.26 + 8.08 x 10-3 T between 310

  8. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Balance › Vitamin D, Calcium, and Bone Health Vitamin D, Calcium, and Bone Health March 2012 Download PDFs ... helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin D ...

  9. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D Do I Need? Amounts of calcium are ...

  10. Calcium transport in turtle bladder

    International Nuclear Information System (INIS)

    Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa). Ouabain reversed JnetCa to an absorptive flux. Amiloride reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

  11. An Improved Calcium Flame Test.

    Science.gov (United States)

    Pearson, Robert S.

    1985-01-01

    Indicates that the true red color of calcium can be obtained (using the procedure described by Sorm and Logowski) if the calcium ion solution is mixed with an equal volume of saturated ammonium bromide solution. Suggestions for flame tests of other elements are also noted. (JN)

  12. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-01-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials. PMID:27411487

  13. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-07-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials.

  14. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells.

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-01-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials. PMID:27411487

  15. CALCIUM ENHANCES ANTIINFLAMMATORY ACTIVITY OF ASPIRIN

    OpenAIRE

    Choksi Krishna; Shenoy Ashoka M; A. R. Shabharaya; Lala Minaxi

    2011-01-01

    The objective of present study is to evaluate the effects of calcium carbonate and calcium gluconate on acute and subacute inflammation and to study their possible interactions with Aspirin. Calcium carbonate (10 mg/kg) and calcium gluconate (5 mg/kg) were administered individually and also co-administered along with sub therapeutic dose Aspirin (50mg/kg) to study their interaction. The inflammation was induced by carrageenan or a foreign body. Both calcium carbonate and calcium gluconate cou...

  16. Vibrational Spectra of Discrete UO22+ Halide Complexes in the Gas Phase

    International Nuclear Information System (INIS)

    The intrinsic binding of halide ions to the metal center in the uranyl molecule is a topic of ongoing research interest in both the actinide separations and theoretical communities. Investigations of structure in the condensed phases is frequently obfuscated by solvent interactions that can alter ligand binding and spectroscopic properties. The approach taken in this study is to move the uranyl halide complexes into the gas phase where they are free from solvent interactions, and then interrogate their vibrational spectroscopy using infrared multiple photon dissociation (IRMPD). The spectra of cationic coordination complexes having the composition (UO2(X)(ACO)3)+ (where X = F, Cl, Br and I; ACO = acetone) were acquired using electrospray for ion formation, and monitoring the ion signal from the photoelimination of ACO ligands. The studies showed that the asymmetric ν3 UO2 frequency was insensitive to halide identity as X was varied from Cl to I, suggesting that in these pseudo-octahedral complexes, changing the nucleophilicity of the halide did not appreciably alter its binding in the complex. The ν3 peak in the spectrum of the F-containing complex was 9 cm-1 lower indicating stronger coordination in this complex. Similarly the ACO carbonyl stretches showed that the C=O frequency was relatively insensitive to the identity of the halide, although a modest shift to higher wavenumber was seen for the complexes with the more nucleophilic anions, consistent with the idea that they loosen solvent binding. Surprisingly, the ν1 stretch was activated when the softer anions Cl, Br and I were present in the complexes. IR studies of the anionic complexes (UO2X3)- (where X = Cl-, Br- and I-) compared the ν3 UO2 modes versus halide, and showed that the ν3 values decreased with increasing anion nucleophilicity. This observation was consistent with DFT calculations that indicated that (UO2X2)--X, and (UO2X2)·-X- dissociation energies decreased on the order F > Cl > Br > I

  17. Vibrational Spectra of Discrete UO₂²⁺ Halide Complexes in the Gas Phase

    Energy Technology Data Exchange (ETDEWEB)

    Groenewold, G S; Van Stipdonk, Michael J; Oomens, Jos; De Jong, Wibe A; Gresham, Garold L; Mcilwain, Michael

    2010-11-01

    The intrinsic binding of halide ions to the metal center in the uranyl molecule is a topic of ongoing research interest in both the actinide separations and theoretical communities. Investigations of structure in the condensed phases is frequently obfuscated by solvent interactions that can alter ligand binding and spectroscopic properties. The approach taken in this study is to move the uranyl halide complexes into the gas phase where they are free from solvent interactions, and then interrogate their vibrational spectroscopy using infrared multiple photon dissociation (IRMPD). The spectra of cationic coordination complexes having the composition [UO₂(X)(ACO)₃]+ (where X = F, Cl, Br and I; ACO = acetone) were acquired using electrospray for ion formation, and monitoring the ion signal from the photoelimination of ACO ligands. The studies showed that the asymmetric ν₃ UO₂ frequency was insensitive to halide identity as X was varied from Cl to I, suggesting that in these pseudo-octahedral complexes, changing the nucleophilicity of the halide did not appreciably alter its binding in the complex. The ν₃ peak in the spectrum of the F-containing complex was 9 cm-1 lower indicating stronger coordination in this complex. Similarly the ACO carbonyl stretches showed that the C=O frequency was relatively insensitive to the identity of the halide, although a modest shift to higher wavenumber was seen for the complexes with the more nucleophilic anions, consistent with the idea that they loosen solvent binding. Surprisingly, the ν1 stretch was activated when the softer anions Cl, Br and I were present in the complexes. IR studies of the anionic complexes [UO₂X₃]- (where X = Cl-, Br- and I-) compared the ν₃ UO₂ modes versus halide, and showed that the ν₃ values decreased with increasing anion nucleophilicity. This observation was consistent with DFT calculations that indicated that [UO

  18. Spectral Features and Charge Dynamics of Lead Halide Perovskites: Origins and Interpretations.

    Science.gov (United States)

    Sum, Tze Chien; Mathews, Nripan; Xing, Guichuan; Lim, Swee Sien; Chong, Wee Kiang; Giovanni, David; Dewi, Herlina Arianita

    2016-02-16

    Lead halide perovskite solar cells are presently the forerunner among the third generation solution-processed photovoltaic technologies. With efficiencies exceeding 20% and low production costs, they are prime candidates for commercialization. Critical insights into their light harvesting, charge transport, and loss mechanisms have been gained through time-resolved optical probes such as femtosecond transient absorption spectroscopy (fs-TAS), transient photoluminescence spectroscopy, and time-resolved terahertz spectroscopy. Specifically, the discoveries of long balanced electron-hole diffusion lengths and gain properties in halide perovskites underpin their significant roles in uncovering structure-function relations and providing essential feedback for materials development and device optimization. In particular, fs-TAS is becoming increasingly popular in perovskite characterization studies, with commercial one-box pump-probe systems readily available as part of a researcher's toolkit. Although TAS is a powerful probe in the study of charge dynamics and recombination mechanisms, its instrumentation and data interpretation can be daunting even for experienced researchers. This issue is exacerbated by the sensitive nature of halide perovskites where the kinetics are especially susceptible to pump fluence, sample preparation and handling and even degradation effects that could lead to disparate conclusions. Nonetheless, with end-users having a clear understanding of TAS's capabilities, subtleties, and limitations, cutting-edge work with deep insights can still be performed using commercial setups as has been the trend for ubiquitous spectroscopy instruments like absorption, fluorescence, and transient photoluminescence spectrometers. Herein, we will first briefly examine the photophysical processes in lead halide perovskites, highlighting their novel properties. Next, we proceed to give a succinct overview of the fundamentals of pump-probe spectroscopy in relation

  19. Mild and Phosphine-Free Iron-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides with Alkynyl Grignard Reagents

    OpenAIRE

    Cheung, Chi Wai; Ren, Peng; Hu, Xile

    2014-01-01

    A simple protocol for iron-catalyzed cross-coupling of nonactivated secondary alkyl bromides and iodides with alkynyl Grignard reagents at room temperature has been developed. A wide range of secondary alkyl halides and terminal alkynes are tolerated to afford the substituted alkynes in good yields. A slight modification of the reaction protocol also allows for cross-coupling with a variety of primary alkyl halides.

  20. Palladium-Catalyzed Hydroxylation of Aryl and Heteroaryl Halides Enabled by the Use of a Palladacycle Precatalyst

    OpenAIRE

    Cheung, Chi Wai; Buchwald, Stephen L.

    2014-01-01

    A method for the hydroxylation of aryl and heteroaryl halides, promoted by a catalyst based on a biarylphosphine ligand tBuBrettPhos (L5) and its corresponding palladium precatalyst (1), is described. The reactions allow the cross-coupling of both potassium and cesium hydroxides with (hetero)aryl halides to afford a variety of phenols and hydroxylated heteroarenes in high to excellent yield.

  1. Fine structures in the optical absorption spectra of photochemical silver in silver halides? A call for further research

    OpenAIRE

    Georgiev, Mladen

    2007-01-01

    A survey is presented of the work done so far to check earlier claims that a fine structure may be observed to occur under certain circumstances in the impurity spectral range of the optical absorption spectra of silver halides following photostimulation in the intrinsic range. This structure, associated with the photochemical formation of silver specks, has been questioned over the years. We now weigh carefully the experimental evidence on the silver halides against a background of similar d...

  2. Fluorogenic derivatization of aryl halides based on the formation of biphenyl by Suzuki coupling reaction with phenylboronic acid.

    OpenAIRE

    Kishikawa, Naoya; Kubo, Kimiko; Hammad, Sherin Farouk; Mabrouk, Mokhtar Mohamed; Habib, Ahmed; Elfatatry, Hamed; Ohyama, Kaname; Nakashima, Kenichiro; Kuroda, Naotaka

    2009-01-01

    The fluorogenic derivatization method for aryl halide was developed for the first time. This method was based on the formation of fluorescent biphenyl structure by Suzuki coupling reaction between aryl halides and non-fluorescent phenylboronic acid (PBA). We measured the fluorescence spectra of the products obtained by the reaction of p-substituted aryl bromides (i.e., 4-bromobenzonitrile, 4-bromoanisole, 4-bromobenzoic acid ethyl ester and 4-bromotoluene) with PBA in the presence of palladiu...

  3. Structural, dynamical, and transport properties of the hydrated halides: How do At- bulk properties compare with those of the other halides, from F- to I-?

    Science.gov (United States)

    Réal, Florent; Severo Pereira Gomes, André; Guerrero Martínez, Yansel Omar; Ayed, Tahra; Galland, Nicolas; Masella, Michel; Vallet, Valérie

    2016-03-01

    The properties of halides from the lightest, fluoride (F-), to the heaviest, astatide (At-), have been studied in water using a polarizable force-field approach based on molecular dynamics (MD) simulations at the 10 ns scale. The selected force-field explicitly treats the cooperativity within the halide-water hydrogen bond networks. The force-field parameters have been adjusted to ab initio data on anion/water clusters computed at the relativistic Möller-Plesset second-order perturbation theory level of theory. The anion static polarizabilities of the two heaviest halides, I- and At-, were computed in the gas phase using large and diffuse atomic basis sets, and taking into account both electron correlation and spin-orbit coupling within a four-component framework. Our MD simulation results show the solvation properties of I- and At- in aqueous phase to be very close. For instance, their first hydration shells are structured and encompass 9.2 and 9.1 water molecules at about 3.70 ± 0.05 Å, respectively. These values have to be compared to the F-, Cl-, and Br- ones, i.e., 6.3, 8.4, and 9.0 water molecules at 2.74, 3.38, and 3.55 Å, respectively. Moreover our computations predict the solvation free energy of At- in liquid water at ambient conditions to be 68 kcal mol-1, a value also close the I- one, about 70 kcal mol-1. In all, our simulation results for I- are in excellent agreement with the latest neutron- and X-ray diffraction studies. Those for the At- ion are predictive, as no theoretical or experimental data are available to date.

  4. Structural, dynamical, and transport properties of the hydrated halides: How do At(-) bulk properties compare with those of the other halides, from F(-) to I(-)?

    Science.gov (United States)

    Réal, Florent; Gomes, André Severo Pereira; Guerrero Martínez, Yansel Omar; Ayed, Tahra; Galland, Nicolas; Masella, Michel; Vallet, Valérie

    2016-03-28

    The properties of halides from the lightest, fluoride (F(-)), to the heaviest, astatide (At(-)), have been studied in water using a polarizable force-field approach based on molecular dynamics (MD) simulations at the 10 ns scale. The selected force-field explicitly treats the cooperativity within the halide-water hydrogen bond networks. The force-field parameters have been adjusted to ab initio data on anion/water clusters computed at the relativistic Möller-Plesset second-order perturbation theory level of theory. The anion static polarizabilities of the two heaviest halides, I(-) and At(-), were computed in the gas phase using large and diffuse atomic basis sets, and taking into account both electron correlation and spin-orbit coupling within a four-component framework. Our MD simulation results show the solvation properties of I(-) and At(-) in aqueous phase to be very close. For instance, their first hydration shells are structured and encompass 9.2 and 9.1 water molecules at about 3.70 ± 0.05 Å, respectively. These values have to be compared to the F(-), Cl(-), and Br(-) ones, i.e., 6.3, 8.4, and 9.0 water molecules at 2.74, 3.38, and 3.55 Å, respectively. Moreover our computations predict the solvation free energy of At(-) in liquid water at ambient conditions to be 68 kcal mol(-1), a value also close the I(-) one, about 70 kcal mol(-1). In all, our simulation results for I(-) are in excellent agreement with the latest neutron- and X-ray diffraction studies. Those for the At(-) ion are predictive, as no theoretical or experimental data are available to date. PMID:27036467

  5. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    International Nuclear Information System (INIS)

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction

  6. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  7. Reactions between cold methyl halide molecules and alkali-metal atoms

    CERN Document Server

    Lutz, Jesse J

    2013-01-01

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH$_{3}X$ ($X$ = F, Cl, Br, I) and alkali-metal atoms $A$ ($A$ = Li, Na, K, Rb) using high-level {\\it ab initio} calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, ${\\rm CH}_{3}X+A\\rightarrow{\\rm CH}_{3}+AX$. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow.

  8. Thermoluminescence response of a mixed ternary alkali halide crystals exposed to gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez M, R.; Perez S, R. [Universidad de Sonora, Departamento de Investigacion en Fisica, Apdo. Postal 5-088, 83190 Hermosillo, Sonora (Mexico); Vazquez P, G.; Riveros, H. [UNAM, Instituto de Fisica, Apdo. Postal 20-364, 01000 Mexico D. F. (Mexico); Gonzalez M, P., E-mail: mijangos@cifus.uson.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-08-15

    Ionic crystals, mainly alkali halide crystals have been the subject of intense research for a better understanding of the luminescence properties of defects induced by ionizing radiation. The defects in crystals can be produced in appreciable concentration due to elastic stresses, radiation, and addition of impurities. These defects exhibit remarkable thermoluminescence properties. This work is concerned with the Tl properties of a ternary alkali halide crystal after being irradiated with gamma and beta rays. It has been found that the Tl glow peak of the crystal follows a rule of average associated to the Tl Temperatures of the components of the mixture, similarly to the response of europium doped binary mixed crystals KCl{sub x}KBr{sub 1-x} and KBr{sub x}RbBr{sub 1-x}. (Author)

  9. XAFS investigations of aqueous zinc halide solutions up to supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, A.J. [Saint Francis Xavier Univ., Antigonish, NS (Canada). Dept. of Geology; Mayanovic, R.A. [Southwest Missouri State Univ., Springfield, MO (United States). Dept. of Physics; Chou, I.M. [US Geological Survey, Reston, VA (United States); Bassett, W.A. [Cornel Univ., Ithica, NY (United States). Dept. of Geological Sciences

    2000-07-01

    The molecular properties of aqueous zinc halide complexes in ore-forming hydrothermal brines was investigated using high temperature zinc (Zn) and bromide (Br) potassium (K)-edge X-ray absorption fine structure (XAFS) measurements of an aqueous zinc bromide solution. The main objective of the study was to determine if there is a relationship between complex hydration and zinc and halide bond distances as a function of temperature. A modified hydrothermal diamond-anvil cell was used as an autoclave. The spectra showed that ZnBr{sub 4}{sup 2-} is the dominant complex up to the supercritical conditions and that the Zn-Br bond lengths decrease as the temperature increases. The Br K-edge data also suggests that an increase in temperature reduces the number of waters surrounding the bromide ligand. 17 refs., 2 tabs., 5 figs.

  10. Reactions of 1,4-bis(tetrazole)benzenes: formation of long chain alkyl halides

    OpenAIRE

    Kelleher, Fintan; Bond, Andrew; Fleming, Adrienne; McGinley, John; Prajapati, Vipa

    2006-01-01

    The reactions of 1,4-bis[2-(tributylstannyl)tetrazol-5-yl]benzene with α,ω-dibromoalkanes were carried out in order to synthesise pendant alkyl halide derivatives of the parent bis-tetrazole. This led to the formation of several alkyl halide derivatives, substituted variously at N1 or N2 on the tetrazole ring. The crystal structures of 1,4-bis[(2-(4-bromobutyl)tetrazol-5-yl)]benzene (2-N,2-N′), 1,4-bis[(2-(4-bromobutyl)tetrazol-5-yl)]benzene (1-N,2-N′) and 1,4-bis[(2-(8-bromooctyl)tetra...

  11. Electric properties of stannous and stannic halides: How good are the experimental values?

    Science.gov (United States)

    Kalugina, Yulia N.; Thakkar, Ajit J.

    2015-04-01

    Coupled-cluster calculations are reported for the electric and vibrational properties of the stannous halides SnX2 and stannic halides SnX4 with X = F, Cl, Br, and I. Comparison with experiment, where available, is made. Our best values of the static mean dipole polarizability for SnF2, SnCl2, SnBr2, and SnI2, are 39.98, 71.93, 91.37, and 125.8 atomic units, respectively. Our best values of the static mean dipole polarizability for SnF4, SnCl4, SnBr4, and SnI4, are 32.82, 93.04, 126.9, and 191.2 atomic units, respectively.

  12. Amine synthesis via iron-catalysed reductive coupling of nitroarenes with alkyl halides.

    Science.gov (United States)

    Cheung, Chi Wai; Hu, Xile

    2016-01-01

    (Hetero)Aryl amines, an important class of organic molecules in medicinal chemistry, are most commonly synthesized from anilines, which are in turn synthesized by hydrogenation of nitroarenes. Amine synthesis directly from nitroarenes is attractive due to improved step economy and functional group compatibility. Despite these potential advantages, there is yet no general method for the synthesis of (hetero)aryl amines by carbon-nitrogen cross-coupling of nitroarenes. Here we report the reductive coupling of nitroarenes with alkyl halides to yield (hetero)aryl amines. A simple iron catalyst enables the coupling with numerous primary, secondary and tertiary alkyl halides. Broad scope and high functional group tolerance are demonstrated. Mechanistic study suggests that nitrosoarenes and alkyl radicals are involved as intermediates. This new C-N coupling method provides general and step-economical access to aryl amines. PMID:27515391

  13. Core-clad silver halide fibers for CO2 laser power transmission

    Science.gov (United States)

    Paiss, Idan; Moser, Frank; Katzir, Abraham

    1991-07-01

    Core-clad optical fibers with efficient IR power delivery are essential components in the development of laser ensoscope systems for surgical applications. The fabrication of such clad fibers of high quality is still an unsolved technical problem. We have investigated parameters of the fabrication of core-clad polyscrystalline silver halide optical fibers and found conditions that yield fibers with relatively good transmittance at 10.6 micrometers (about 3 dB/meter loss) and capable of delivering output power densities up to 3 kwatt/cm2 in CW operation. This performance is lower than what we achieved in core-only silver halide fibers, but the advantage of the protection provided by the clad and a subsequent plastic overcoat, make these core-clad fibers useful in a number of CO2 power transmission applications in laser surgery.

  14. Microscopic Investigation of Grain Boundaries in Organolead Halide Perovskite Solar Cells.

    Science.gov (United States)

    Li, Jiang-Jun; Ma, Jing-Yuan; Ge, Qian-Qing; Hu, Jin-Song; Wang, Dong; Wan, Li-Jun

    2015-12-30

    Grain boundaries (GBs) play an important role in organic-inorganic halide perovskite solar cells, which have generally been recognized as a new class of materials for photovoltaic applications. To definitely understand the electrical structure and behavior of GBs, here we present Kelvin probe force microscopy and conductive atomic force microscopy (c-AFM) measurements of both typical and inverted planar organolead halide perovskite solar cells. By comparing the contact potential difference (CPD) of these two devices in the dark and under illumination, we found that a downward band bending exists in GBs that predominantly attract photoinduced electrons. The c-AFM measurements observed that higher photocurrents flow through GBs when a low bias overcomes the barrier created by the band bending, indicating that GBs act as effective charge dissociation interfaces and photocurrent transduction pathways rather than recombination sites. PMID:26633192

  15. Reactions between cold methyl halide molecules and alkali-metal atoms

    International Nuclear Information System (INIS)

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH3X (X = F, Cl, Br, I) and alkali-metal atoms A (A = Li, Na, K, Rb) using high-level ab initio calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, CH3X + A → CH3 + AX. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow

  16. A Simple Halide-to-Anion Exchange Method for Heteroaromatic Salts and Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Neus Mesquida

    2012-04-01

    Full Text Available A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A− form in non-aqueous media. The anion loading of the AER (OH− form was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A− form method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH3OH, CH3CN and the dipolar nonhydroxylic solvent mixture CH3CN:CH2Cl2 (3:7 and the anion exchange was equally successful with both lipophilic cations and anions.

  17. Solid-State Nanopore Confinement for Band Gap Engineering of Metal-Halide Perovskites

    CERN Document Server

    Demchyshyn, Stepan; Groiss, Heiko; Heilbrunner, Herwig; Ulbricht, Christoph; Apaydin, Dogukan; Rütt, Uta; Bertram, Florian; Hesser, Günter; Scharber, Markus; Nickel, Bert; Sariciftci, Niyazi Serdar; Bauer, Siegfried; Głowacki, Eric Daniel; Kaltenbrunner, Martin

    2016-01-01

    Tuning the band gap of semiconductors via quantum size effects launched a technological revolution in optoelectronics, advancing solar cells, quantum dot light-emitting displays, and solid state lasers. Next generation devices seek to employ low-cost, easily processable semiconductors. A promising class of such materials are metal-halide perovskites, currently propelling research on emerging photovoltaics. Their narrow band emission permits very high colour purity in light-emitting devices and vivid life-like displays paired with low-temperature processing through printing-compatible methods. Success of perovskites in light-emitting devices is conditional upon finding reliable strategies to obtain tunability of the band gap. So far, colour can be tuned chemically by mixed halide stoichiometry, or by synthesis of colloidal particles. Here we introduce a general strategy of controlling shape and size of perovskite nanocrystallites (less than 10 nm) in domains that exhibit strong quantum size effects. Without ma...

  18. Coloration of cadmium halide crystals due to reactor irradiation at low temperature

    International Nuclear Information System (INIS)

    The optical absorption spectra and ESR spectra of cadmium halide crystals were measured after the reactor irradiation at low temperature to study the coloration. The irradiated neutron dose was about 5 x 1017 n/cm2. In the measurement of ESR spectra, the crystal was rotated around the v-axis (the two-fold axis) in the magnetic field of fixed direction. The optical absorption spectra showed that the Cd3+ center was generated. From the analysis of the angular dependence of ESR spectra, the centers of C(2h) symmetry and the centers of D(3d) symmetry were considered to be generated. The models of these centers were considered, and the angular dependence was analyzed. It can be concluded from the present experiment that the coloration of cadmium halide crystals is recognized as the results of the reactor irradiation at low temperature. (Kato, T.)

  19. Energetics and dynamics in organic-inorganic halide perovskite photovoltaics and light emitters.

    Science.gov (United States)

    Sum, Tze Chien; Chen, Shi; Xing, Guichuan; Liu, Xinfeng; Wu, Bo

    2015-08-28

    The rapid transcendence of organic-inorganic metal halide perovskite solar cells to above the 20% efficiency mark has captivated the broad photovoltaic community. As the efficiency race continues unabated, it is essential that fundamental studies keep pace with these developments. Further gains in device efficiencies are expected to be increasingly arduous and harder to come by. The key to driving the perovskite solar cell efficiencies towards their Shockley-Queisser limit is through a clear understanding of the interfacial energetics and dynamics between perovskites and other functional materials in nanostructured- and heterojunction-type devices. In this review, we focus on the current progress in basic characterization studies to elucidate the interfacial energetics (energy-level alignment and band bending) and dynamical processes (from the ultrafast to the ultraslow) in organic-inorganic metal halide perovskite photovoltaics and light emitters. Major findings from these studies will be distilled. Open questions and scientific challenges will also be highlighted. PMID:26234397

  20. Correlations for calculating the surface tension and enthalpies of sublimation of alkali halides

    International Nuclear Information System (INIS)

    The capability of a new model on predicting the surface tension of molten alkali halides is described. A relationship, with a simple form of calculation, exists between the surface tension (γ) at the melting point, molar volume (V), inter-nuclear distance (D) and the enthalpy of sublimation (Es). The basic idea results from the assumption that all the parameters are constants that are usually easy to acquire. Moreover, two previous models (Furth and Schytil equations) were also checked and applied for calculating surface tension of molten salts. The three formulas have been examined for 20 salts and showed remarkable agreement between calculated and experimental data with a difference of less than 10% for most of the salts studied. The heats of sublimation of alkali halides were, theoretically, calculated and compared to literature values.

  1. Enhanced phosphorescence emission by incorporating aromatic halides into an entangled coordination framework based on naphthalenediimide.

    Science.gov (United States)

    Martínez-Martínez, Virginia; Sola Llano, Rebeca; Furukawa, Shuhei; Takashima, Yohei; López Arbeloa, Iñigo; Kitagawa, Susumu

    2014-08-25

    Phosphorescence emission at room temperature is turned on in an entangled porous coordination polymer (PCP) with naphthalenediimide (NDI) as chromophore, by incorporating halogenated guests into the pores. The phosphorescent efficiency is drastically increased by the incorporation of aromatic halide guests in comparison with the incorporation of nonaromatic derivatives. Aromatic halide guests trigger a structural transformation, which allows a strong interaction with the NDI ligand in the framework through charge-transfer complexation, and provides an extra population process of the triplet state. The long-lived photoinduced triplet states, with an emission wavelength in the red region of the visible spectrum, demonstrated by this PCP, may open the door for potential uses, for example, as singlet-oxygen generators or for bio-imaging applications. PMID:24953198

  2. Stability diagrams for fourfold coordination of polyvalent metal ions in molten mixtures of halide salts

    International Nuclear Information System (INIS)

    The stability of local fourfold coordination for divalent and trivalent metal ions in liquid mixtures of polyvalent metal halides and alkali halides is classified by means of structural coordinates obtained from properties of the elements. In parallel with earlier classifications of compound crystal structures and molecular shapes, the elemental properties are taken from first-principles calculations of valence electron orbitals in atoms, in the form of (i) the nodal radii of Andreoni, Baldereschi and Guizzetti or (ii) the pseudopotential radii or Zunger and Cohen. As a third alternative a classification based on Pettifor's phenomenological chemical scale of the elements is also considered. The alternative structural classification schemes that are developed from these elemental properties are generally successfully in distinguishing molten mixtures in which the available experimental evidence indicates long-lived fourfold coordination of polyvalent metal ions. In addition, Pettifor's chemical scale scheme is useful in sorting out finer details of local coordination in the liquid state. 3 figs., 71 refs

  3. Tuning the thermal conductivity of methylammonium lead halide by the molecular substructure.

    Science.gov (United States)

    Caddeo, Claudia; Melis, Claudio; Saba, Maria Ilenia; Filippetti, Alessio; Colombo, Luciano; Mattoni, Alessandro

    2016-09-21

    By using state-of-the-art atomistic methods we provide an accurate estimate of thermal conductivity of methylammonium lead halide as a function of sample size and temperature, in agreement with experimental works. We show that the thermal conductivity of methylammonium lead halide is intrinsically low, due to the low sound velocity of the PbI lattice. Furthermore, by selectively analyzing the effect of different molecular degrees of freedom, we clarify the role of the molecular substructure by showing that the internal modes above 150 cm(-1) (in addition to rotations) are effective in reducing the thermal conductivity of hybrid perovskites. This analysis suggests strategies to tailor the thermal conductivity by modifying the internal structure of organic cations. PMID:27531063

  4. Spacial Structure of Cationic Phosphorus Ligand-Ru (Ⅱ) Halide Complexes-by DFT Study

    Institute of Scientific and Technical Information of China (English)

    Yi Xin ZHAO; Shu Guang WANG

    2005-01-01

    The full-parameter geometry optimization of cationic (S)-BINAP-Ru (Ⅱ) halide complex was performed by DFT method using B3LYP, PW91 and PBE potentials with several basis sets. PW91 with 3-21G / SDD basis sets is found to be the most suitable method with consideration of both precision and efficiency. The dihedral angles (θ) of the binaphthyl or biphenyl with different phosphorus ligand-Ru (Ⅱ) halide complexes were found changing from 59.9 to 79.3 degree, while the natural bite angle (βn) of those complexes only changes from 87.4to 90.3 degree. It is different from the common view of asymmetric organic chemists' that θ directly influences βn.

  5. Structural stability, acidity, and halide selectivity of the fluoride riboswitch recognition site

    KAUST Repository

    Chawla, Mohit

    2015-01-14

    Using static and dynamics DFT methods we show that the Mg2+/F-/phosphate/water cluster at the center of the fluoride riboswitch is stable by its own and, once assembled, does not rely on any additional factor from the overall RNA fold. Further, we predict that the pKa of the water molecule bridging two Mg cations is around 8.4. We also demonstrate that the halide selectivity of the fluoride riboswitch is determined by the stronger Mg-F bond, which is capable of keeping together the cluster. Replacing F- with Cl- results in a cluster that is unstable under dynamic conditions. Similar conclusions on the structure and energetics of the cluster in the binding pocket of fluoride-inhibited pyrophosphatase suggest that the peculiarity of fluoride is in its ability to establish much stronger metal-halide bonds.

  6. Intermolecular interactions and proton transfer in the hydrogen halide-superoxide anion complexes.

    Science.gov (United States)

    Lee, Sebastian J R; Mullinax, J Wayne; Schaefer, Henry F

    2016-02-17

    The superoxide radical anion O2(-) is involved in many important chemical processes spanning different scientific disciplines (e.g., environmental and biological sciences). Characterizing its interaction with various substrates to help elucidate its rich chemistry may have far reaching implications. Herein, we investigate the interaction between O2(-) (X[combining tilde] (2)Πg) and the hydrogen halides (X[combining tilde] (1)Σ) with coupled-cluster theory. In contrast to the short (1.324 Å) hydrogen bond formed between the HF and O2(-) monomers, a barrierless proton transfer occurs for the heavier hydrogen halides with the resulting complexes characterized as long (>1.89 Å) hydrogen bonds between halide anions and the HO2 radical. The dissociation energy with harmonic zero-point vibrational energy (ZPVE) for FHO2(-) (X[combining tilde] (2)A'') → HF (X[combining tilde] (1)Σ) + O2(-) (X[combining tilde] (2)Πg) is 31.2 kcal mol(-1). The other dissociation energies with ZPVE for X(-)HO2 (X[combining tilde] (2)A'') → X(-) (X[combining tilde] (1)Σ) + HO2 (X[combining tilde] (2)A'') are 25.7 kcal mol(-1) for X = Cl, 21.9 kcal mol(-1) for X = Br, and 17.9 kcal mol(-1) for X = I. Additionally, the heavier hydrogen halides can form weak halogen bonds H-XO2(-) (X[combining tilde] (2)A'') with interaction energies including ZPVE of -2.3 kcal mol(-1) for HCl, -8.3 kcal mol(-1) for HBr, and -16.7 kcal mol(-1) for HI. PMID:26852733

  7. Temperature Dependence of Interatomic Separation and Bulk Modulus for Alkali Halides

    Science.gov (United States)

    Liu, Quan

    2016-07-01

    The values of interatomic separation r with the change of temperature T for seven alkali halides have been investigated with the help of an isobaric equation of state. The calculated results are used to predict the values of bulk modulus at different temperatures. The results are compared with the available experimental data and other theoretical results and are further discussed in view of recent research in the field of high temperature physics.

  8. Mössbauer Emission-Spectra of Impurity Cobalt-57 in a Halide Matrix

    DEFF Research Database (Denmark)

    Maddock, A. G.; Williams, A. F.; Siekierska, K. E.;

    1976-01-01

    The Mössbauer emission spectra of 57Co in low concentrations in KF, NaCl, NaF, LiF, and MgF2, and the effects of doping NaF and LiF with La3+ ions are reported. The monovalent halides all give similar spectra showing a broad single line or a doublet at 2.19mm/s and two overlapping doublets at 0...

  9. Tailoring Mixed-Halide, Wide-Gap Perovskites via Multistep Conversion Process

    DEFF Research Database (Denmark)

    Bae, Dowon; Palmstrom, Axel; Roelofs, Katherine;

    2016-01-01

    Wide-band-gap mixed-halide CH3NH3PbI3–XBrX-based solar cells have been prepared by means of a sequential spin-coating process. The spin-rate for PbI2 as well as its repetitive deposition are important in determining the cross-sectional shape and surface morphology of perovskite, and, consequently...

  10. Theoretical analysis of the kinetics of low-temperature defect recombination in alkali halide crystals

    Science.gov (United States)

    Kuzovkov, V. N.; Popov, A. I.; Kotomin, E. A.; Moskina, A. M.; Vasilchenko, E.; Lushchik, A.

    2016-07-01

    We analyzed carefully the experimental kinetics of the low-temperature diffusion-controlled F, H center recombination in a series of irradiated alkali halides and extracted the migration energies and pre-exponential parameters for the hole H centers. The migration energy for the complementary electronic F centers in NaCl was obtained from the colloid formation kinetics observed above room temperature. The obtained parameters were compared with data available from the literature.

  11. Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

    OpenAIRE

    Xiaoqian Ai; Yuchen Tian; Min Gu; Ji Yu; Tong B. Tang

    2016-01-01

    The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18) intercalated in graphite oxide (GO) have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16) or bilayers (when n = 18), with their long axis para...

  12. Thick phase holographic gratings recorded on BB-640 and PFG-01 silver halide materials

    OpenAIRE

    Neipp López, Cristian; Márquez Ruiz, Andrés; Pascual Villalobos, Inmaculada; Beléndez Vázquez, Augusto

    2002-01-01

    Photographic emulsions are still widely used to record holographic optical elements. In particular, if high diffraction efficiencies are needed, phase volume holograms are preferably recorded on these emulsions. Two particular techniques producing high-quality volume phase holograms are fixation-free rehalogenating bleaching and the use of silver-halide-sensitized gelatin. In this work we compare these two particular techniques applied to three different red-sensitive emulsions: Agfa 8E75 HD,...

  13. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    International Nuclear Information System (INIS)

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl2 nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI2 is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu2+/Eu3+ ratio in the glass ceramics should be determined and optimize favor of the Eu2+. We also want to distinguish between Eu2+ in the glass matrix and Eu2+ in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a CaF2 host lattice were carried out. (orig.)

  14. Propensity of heavier halides for the water/vapor interface revisited using the Amoeba force field

    Czech Academy of Sciences Publication Activity Database

    Tůma, L.; Jeníček, D.; Jungwirth, Pavel

    2005-01-01

    Roč. 411, - (2005), s. 70-74. ISSN 0009-2614 R&D Projects: GA MŠk(CZ) LC512 Grant ostatní: NSF(US) CHE0431312; NSF(US) CHE0209719 Institutional research plan: CEZ:AV0Z4055905 Keywords : halide anions * water/vapor interface * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.438, year: 2005

  15. An air-stable copper reagent for nucleophilic trifluoromethylthiolation of aryl halides

    KAUST Repository

    Weng, Zhiqiang

    2012-12-12

    A series of copper(I) trifluoromethyl thiolate complexes have been synthesized from the reaction of CuF2 with Me3SiCF 3 and S8 (see scheme; Cu red, F green, N blue, S yellow). These air-stable complexes serve as reagents for the efficient conversion of a wide range of aryl halides into the corresponding aryl trifluoromethyl thioethers in excellent yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Size-Dependent Photon Emission from Organometal Halide Perovskite Nanocrystals Embedded in an Organic Matrix

    OpenAIRE

    Di, Dawei; Musselman, Kevin P.; Li, Guangru; Sadhanala, Aditya; Ievskaya, Yulia; Song, Qilei; Tan, Zhi-Kuang; Lai, May Ling; MacManus-Driscoll, Judith L; Greenham, Neil C.; Friend, Richard H

    2015-01-01

    In recent years, organometal halide perovskite materials have attracted significant research interest in the field of optoelectronics. Here, we introduce a simple and low-temperature route for the formation of self-assembled perovskite nanocrystals in a solid organic matrix. We demonstrate that the size and photoluminescence peak of the perovskite nanocrystals can be tuned by varying the concentration of perovskite in the matrix material. The physical origin of the blue shift of the perovskit...

  17. Calculation of shear angles in holographic gratings recorded in bleached silver-halide emulsions

    OpenAIRE

    Beléndez Vázquez, Augusto; Pascual Villalobos, Inmaculada; Fuentes Rosillo, Rosa; Fimia Gil, Antonio

    1993-01-01

    Shearing phenomena in holographic gratings formed in bleached silver-halide emulsions due to chemical processing are evaluated. These effects are introduced because of the inability of emulsion-thickness changes to explain the anomalous detuning of the peak diffraction efficiency from the expected Bragg condition. Experimental results obtained with transmission and reflection gratings are presented and discussed considering shearing effects, and the values of the shear angles calculated from ...

  18. Three-Component Halo Aldol Condensation of Thioacrylates with Aldehydes Mediated by Titanium (IV Halide

    Directory of Open Access Journals (Sweden)

    Guigen Li

    2002-01-01

    Full Text Available a,b-Ethyl thioacrylate was difuctionalized by a tandem X-C/C=C bond formation reaction. The new system uses Ti (IV halide as both the Lewis acidic promoter and the halogen source for the Michael-type addition onto the thioacrylate. The titanium enolate species resulting from Michael-type addition react with aldehydes followed by dehydration to afford trisubstituted olefin products. Complete geometric selectivity (>95% and up to 72% yield have been obtained for 7 examples.

  19. Three-Component Halo Aldol Condensation of Thioacrylates with Aldehydes Mediated by Titanium (IV) Halide

    OpenAIRE

    Guigen Li; Gao, Joe J.; Han-Xun Wei; Sun Hee Kim

    2002-01-01

    a,b-Ethyl thioacrylate was difuctionalized by a tandem X-C/C=C bond formation reaction. The new system uses Ti (IV) halide as both the Lewis acidic promoter and the halogen source for the Michael-type addition onto the thioacrylate. The titanium enolate species resulting from Michael-type addition react with aldehydes followed by dehydration to afford trisubstituted olefin products. Complete geometric selectivity (>95%) and up to 72% yield have been obtained for 7 examples.

  20. Circular Photogalvanic Effect in Organometal Halide Perovskite CH$_3$NH$_3$PbI$_3$

    OpenAIRE

    Li, Junwen; Haney, Paul M.

    2016-01-01

    We study the circular photogalvanic effect in the organometal halide perovskite solar cell absorber CH$_3$NH$_3$PbI$_3$. For crystal structures which lack inversion symmetry, the calculated photocurrent density is about $10^{-9}$ A/W, comparable to the previously studied quantum well and bulk Rashba systems. Because of the dependence of the circular photogalvanic effect on inversion symmetry breaking, the degree of inversion asymmetry at different depths from the surface can be probed by tuni...

  1. Can Ferroelectric Polarization Explain the High Performance of Hybrid Halide Perovskite Solar Cells?

    OpenAIRE

    Sherkar, Tejas; Koster, L Jan Anton

    2016-01-01

    The power conversion efficiency of photovoltaic cells based on the use of hybrid halide perovskites, CH3NH3PbX3 (X = Cl, Br, I), now exceeds 20%. Recently, it was suggested that this high performance originates from the presence of ferroelectricity in the perovskite, which is hypothesized to lower charge recombination in the device. Here, we investigate and quantify the influence of mesoscale ferroelectric polarization on the device performance of perovskite solar cells. We implement a 3D dri...

  2. Intrinsic femtosecond charge generation dynamics in a single crystal organometal halide perovskite

    OpenAIRE

    Valverde-Chávez, David A.; Ponseca Jr., Carlito; Stoumpos, Constantinos; Yartsev, Arkady; Kanatzidis, Mercouri G.; Sundström, Villy; Cooke, David G.

    2015-01-01

    Hybrid metal-organic perovskite solar cells have astounded the solar cell community with their rapid rise in efficiency over the past three years. Despite this success, the basic processes governing the photogeneration of free charges, particularly their dynamics and efficiency, remain unknown. Here we use ultrabroadband pulses of THz frequency light to see the intrinsic photophysical properties of single crystal lead halide perovskite just femtoseconds after a photon is first absorbed. Our s...

  3. Optical Description of Mesostructured Organic¿Inorganic Halide Perovskite Solar Cells

    OpenAIRE

    Anaya, Miguel; Lozano, Gabriel; Calvo, Mauricio E.; Zhang, Wei; Johnston, Michael B; Snaith, Henry J.; Míguez, Hernán

    2015-01-01

    Herein we describe both theoretically and experimentally the optical response of solution-processed organic¿inorganic halide perovskite solar cells based on mesostructured scaffolds. We develop a rigorous theoretical model using a method based on the propagation of waves in layered media, which allows visualizing the way in which light is spatially distributed across the device and serves to quantify the fraction of light absorbed by each medium comprising the cell. The discrimination between...

  4. Simultaneous Analyses and Applications of Multiple Fluorobenzoate and Halide Tracers in Hydrologic Studies

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Q; Moran, J E

    2004-01-22

    An analytical method that employs ion chromatography has been developed to more fully exploit the use of fluorobenzoic acids (FBAs) and halides as hydrologic tracers. In a single run, this reliable, sensitive, and robust method can simultaneously separate and quantify halides (fluoride, chloride, bromide, and iodide) and up to seven FBAs from other common groundwater constituents (e.g., nitrate and sulfate). The usefulness of this ion chromatographic (IC) analytical method is demonstrated in both field and laboratory tracer experiments. Field experiments in unsaturated tuff featuring fractures or a fault show that this efficient and cost-effective method helps achieve the objectives of tracer studies that use multiple FBAs and/or diffusivity tracers (simultaneous use of one or more FBA and halide). The field study examines the hydrologic response of fractures and the matrix to different flow rates and the contribution of matrix diffusion in chemical transport. Laboratory tracer experiments with eight geologic media from across the United States--mostly from Department of Energy facilities where groundwater contamination is prevalent and where subsurface characterization employing tracers has been ongoing or is in need--reveal several insights about tracer transport behavior: (1) Bromide and FBAs are not always transported conservatively. (2) The delayed transport of these anionic tracers is likely related to geologic media characteristics, such as organic matter, pH, iron oxide content, and clay mineralogy. (3) Any use of iodine as a hydrologic tracer should take into account the different sorption behaviors of iodide and iodate and the possible conversion of iodine's initial chemical form. (4) The transport behavior of potential FBA and halide tracers under relevant geochemical conditions should be evaluated before beginning ambitious, large-scale field tracer experiments.

  5. Study on growth of ternary alkali lead halide crystals for IR lasers

    Czech Academy of Sciences Publication Activity Database

    Král, Robert

    Berlin : Polyprint GmbH, 2011, s. 146-147. [International Workshop on Crystal Growth Technology/5./. Berlin (DE), 26.06.2011-30.06.2011] R&D Projects: GA AV ČR KJB200100901 Institutional research plan: CEZ:AV0Z10100521 Keywords : interface s * vertical Bridgman method * ternary alkali lead halides * solid state lasers Subject RIV: BM - Solid Matter Physics ; Magnetism https://iwcgt5.ikz-berlin.de/index.php?id=18

  6. Physical methods of preparing high-purity scandium and electrorefining in halide

    International Nuclear Information System (INIS)

    Capabilities of the physical methods (vacuum melting, vacuum distillation and sublimation, zone melting) of producing high-purity metal scandium are analyzed based on literary and fundamental data, and their comparison to electrorefining in halide melts is considered. Advantages and disadvantages of the methods are demonstrated. A conclusion is made about a high competitiveness of electrorefining in saline melts for the production of high-purity scandium

  7. Mechanoluminescence produced during cleavage of γ-irradiated alkali halide crystals

    International Nuclear Information System (INIS)

    When g-irradiated alkali halide crystals are cleaved, then in their mechanoluminescence (ML) intensity versus time curve, two peak intensities Im1 and Im2 are observed at time tm1 and tm2 respectively. The ML intensity both beyond tm1 and tm2 decrease exponentially. It is shown that ML provides a new technique for determining the pinning time of dislocations and lifetime of the electrons in dislocation band. (author)

  8. Determination of stable and long-lived radioactive halides using high resolution ICP-MS

    International Nuclear Information System (INIS)

    Routine control of radioactive waste demands efficient techniques which allow many samples to be analyzed per day with high precision and accuracy. ICP-MS is well established as a trace analytical method and permits the extremely sensitive and fast detection of stable and long-lived radioactive nuclides. Though ICP-MS is rarely used for the determination of halides, the author's investigation shows that a sufficient low detection limit can be achieved (e.g., for the declaration of 129I in radioactive waste samples.). In this work, a double focusing mass spectrometer with an ICP ion source (open-quotes ELEMENTclose quotes, Finnigan MAT) is used for the determination of halides (Cl, Br and I) in biological standard reference materials as well as 129I in low-activity radioactive waste samples. A method was developed for the determination of halides in the μg/mL-range for bromine and chlorine and the ng/mL-range for iodine including isotopic analysis of stable and radioactive halides. Possible interferences of atomic ions with other ions (e.g., 129I+ with 129Xe+) were investigated and possibilities for correction of these interferences will be discussed. To achieve a lower detection limit a new method for iodine sample introduction was developed. The iodide ion in an aqueous sample is oxidized to elemental iodine and introduced directly into the ICP by a special introduction system. Iodine (127I or 129I) can be measured by this new method even in the lower ng/mL-range. The studies were extended to include the determination of bromine and chlorine

  9. Photokeratitis Linked to Metal Halide Bulbs in Two Gymnasiums - Philadelphia, Pennsylvania, 2011 and 2013.

    Science.gov (United States)

    Finn, Lauren E; Gutowski, Jennifer; Alles, Steve; Mirowitz, Naomi; Johnson, Caroline; Osterhoudt, Kevin C; Patel, Ami

    2016-01-01

    In December 2011 and December 2013, the Philadelphia Department of Public Health (PDPH) received separate reports of clusters of photokeratitis linked to gymnasium events. Photokeratitis, a painful eye condition resulting from unprotected exposure to ultraviolet radiation, has previously been linked to metal halide lamps with broken outer envelopes (1,2). To investigate the cause of these clusters and further characterize patients with photokeratitis, PDPH administered questionnaires to potentially exposed persons, established a case definition, and conducted environmental assessments of both gymnasiums. Because event attendee registration information was available, a cohort study was conducted to evaluate the 2011 cluster of 242 persons who met the photokeratitis case definition. A case-series investigation was conducted to evaluate the 2013 cluster of 20 persons who met the photokeratitis case definition for that event. These investigations indicated that Type R metal halide bulbs with broken outer envelopes found in both gymnasiums were the probable cause of the photokeratitis. The Food and Drug Administration has made a number of recommendations regarding the use of metal halide bulbs in facilities where bulbs are at elevated risk for breaking, such as schools and indoor sports facilities (3). Because Type R metal halide lamps do not self-extinguish once the outer envelope is broken, these bulbs should be removed from settings with a high risk for outer envelope rupture, such as gymnasiums, or should be placed within enclosed fixtures. In instances where these bulbs cannot be exchanged for self-extinguishing lamps, Type R lamps with a broken outer envelope should be replaced immediately to limit exposure to ultraviolet radiation. A broken outer envelope can be detected by the presence of glass on the floor, or visual examination of the bulb when the power is turned off. A broken outer envelope is difficult to detect when the lamp is emitting light. PMID

  10. Seed-mediated growth of palladium nanocrystals: The effect of pseudo-halide thiocyanate ions

    Science.gov (United States)

    Zhang, Ling; Niu, Wenxin; Xu, Guobao

    2011-02-01

    In synthesis in a solution phase, adsorbates such as halides can interact selectively with different metal crystal facets and affect the final morphology of nanocrystals. Pseudo-halide thiocyanate ions (SCN-) can also adsorb on the metal surface, but they have never been used for the synthesis of shape-controlled colloidal metal nanocrystals. In this study, we first investigated the effect of SCN- on the morphology of palladium nanocrystals through a seed-mediated growth method. The presence of 1 µM SCN- in the growth solutions could lead to the formation of palladium polyhedra: truncated rhombic dodecahedra enclosed by twelve {110}, eight {111} and six {100} facets. The products were nanocubes enclosed with six {100} facets if cetyltrimethylammonium bromide (CTAB) was the only capping agent. Meanwhile, the mechanism of the effect of SCN- on the morphology of Pd nanocrystals is discussed.In synthesis in a solution phase, adsorbates such as halides can interact selectively with different metal crystal facets and affect the final morphology of nanocrystals. Pseudo-halide thiocyanate ions (SCN-) can also adsorb on the metal surface, but they have never been used for the synthesis of shape-controlled colloidal metal nanocrystals. In this study, we first investigated the effect of SCN- on the morphology of palladium nanocrystals through a seed-mediated growth method. The presence of 1 µM SCN- in the growth solutions could lead to the formation of palladium polyhedra: truncated rhombic dodecahedra enclosed by twelve {110}, eight {111} and six {100} facets. The products were nanocubes enclosed with six {100} facets if cetyltrimethylammonium bromide (CTAB) was the only capping agent. Meanwhile, the mechanism of the effect of SCN- on the morphology of Pd nanocrystals is discussed. Electronic supplementary information (ESI) available: Additional SEM, TEM and XRD data. See DOI: 10.1039/c0nr00622j

  11. Structural and functional analysis of a novel haloalkane dehalogenase with two halide-binding sites

    Czech Academy of Sciences Publication Activity Database

    Chaloupková, R.; Prudnikova, T.; Řezáčová, Pavlína; Prokop, Z.; Koudeláková, T.; Daniel, L.; Březovský, J.; Ikeda-Ohtsubo, W.; Sato, Y.; Kutý, Michal; Nagata, Y.; Kutá-Smatanová, Ivana; Damborský, J.

    2014-01-01

    Roč. 70, July (2014), s. 1884-1897. ISSN 0907-4449 Grant ostatní: GA ČR(CZ) GAP207/12/0775; GA MŠk(CZ) LO1214; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 ; RVO:67179843 Keywords : haloalkane dehalogenase * halide-binding site * catalytic activity * substrate specificity * enzyme stability Subject RIV: CE - Biochemistry Impact factor: 7.232, year: 2013

  12. Enantioselective Cross-Coupling of meso-Epoxides with Aryl Halides

    OpenAIRE

    Zhao, Yang; Weix, Daniel J.

    2015-01-01

    The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78–95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal, trifluoromethyl, sulfonamide, sulfonate ester), both aryl and vinyl halides, and five- to seven...

  13. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    Science.gov (United States)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  14. NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning.

    Science.gov (United States)

    Shmyreva, Anna A; Safdari, Majid; Furó, István; Dvinskikh, Sergey V

    2016-06-14

    Orders of magnitude decrease of (207)Pb and (199)Hg NMR longitudinal relaxation times T1 upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX2 (Me = Pb, Hg and X = Cl, Br, I). In lead(ii) halides, the most dramatic decrease of T1 relative to that in a static sample is in PbI2, while it is smaller but still significant in PbBr2, and not detectable in PbCl2. The effect is magnetic-field dependent but independent of the spinning speed in the range 200-15 000 Hz. The observed relaxation enhancement is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time. PMID:27306000

  15. On the Thermal and Thermodynamic (In)Stability of Methylammonium Lead Halide Perovskites

    Science.gov (United States)

    Brunetti, Bruno; Cavallo, Carmen; Ciccioli, Andrea; Gigli, Guido; Latini, Alessandro

    2016-01-01

    The interest of the scientific community on methylammonium lead halide perovskites (MAPbX3, X = Cl, Br, I) for hybrid organic-inorganic solar cells has grown exponentially since the first report in 2009. This fact is clearly justified by the very high efficiencies attainable (reaching 20% in lab scale devices) at a fraction of the cost of conventional photovoltaics. However, many problems must be solved before a market introduction of these devices can be envisaged. Perhaps the most important to be addressed is the lack of information regarding the thermal and thermodynamic stability of the materials towards decomposition, which are intrinsic properties of them and which can seriously limit or even exclude their use in real devices. In this work we present and discuss the results we obtained using non-ambient X-ray diffraction, Knudsen effusion-mass spectrometry (KEMS) and Knudsen effusion mass loss (KEML) techniques on MAPbCl3, MAPbBr3 and MAPbI3. The measurements demonstrate that all the materials decompose to the corresponding solid lead (II) halide and gaseous methylamine and hydrogen halide, and the decomposition is well detectable even at moderate temperatures (~60 °C). Our results suggest that these materials may be problematic for long term operation of solar devices. PMID:27545661

  16. NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning

    Science.gov (United States)

    Shmyreva, Anna A.; Safdari, Majid; Furó, István; Dvinskikh, Sergey V.

    2016-06-01

    Orders of magnitude decrease of 207Pb and 199Hg NMR longitudinal relaxation times T1 upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX2 (Me = Pb, Hg and X = Cl, Br, I). In lead(ii) halides, the most dramatic decrease of T1 relative to that in a static sample is in PbI2, while it is smaller but still significant in PbBr2, and not detectable in PbCl2. The effect is magnetic-field dependent but independent of the spinning speed in the range 200-15 000 Hz. The observed relaxation enhancement is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time.

  17. Line emissions from sonoluminescence in aqueous solutions of halide salts without noble gases

    International Nuclear Information System (INIS)

    Line emissions of trivalent terbium (Tb3+) ion were observed from single-bubble sonoluminescence (SL) in an aqueous solution of terbium chloride (TbCl3) that contained no noble gas. In addition, sodium (Na) lines were observed in multi-bubble SL in aqueous solutions of various halide salts that contained no noble gas. These observations show that the halide ions, such as Cl−, Br−, and I−, help for line emissions as the noble gases. The intensity of a line emission depends on both the chemical species produced by cavitation bubbles and the temperature of SL bubble that responds to the driving ultrasound pressure. With the increase of driving pressure, some line emissions attached to the continuous spectrum may become increasingly clear, while other line emissions gradually become indistinct. - Highlights: • Line emissions of Tb(III) ions were observed without the presence of noble gases. • The halide ions help to generate a line emission during sonoluminescence. • The intensity of a line emission mainly depends on the bubble's temperature. • The definition of a line emission is related to the temperature of caviation bubble and the kind of host liquid

  18. Third-order elastic moduli for alkali-halide crystals possessing the sodium chloride structure

    Energy Technology Data Exchange (ETDEWEB)

    Ray, U., E-mail: ray_ugrasen@yahoo.co [Department of Physics, Bhaktapur Multiple Campus, Tribhuvan University, Kathmandu (Nepal)

    2010-08-01

    The values of third-order elastic moduli for alkali halides, having NaCl-type crystal structure are calculated according to the Born-Mayer potential model, considering the repulsive interactions up to the second nearest neighbours and calculating the values of the potential parameters for each crystal, independently, from the compressibility data. This work presents the first published account of the calculation of the third-order elastic moduli taking the actual value of the potential parameter unlike the earlier works. Third-order elastic constants have been computed for alkali halides at 0 and 300 K. The results of the third-order elastic constants are compared with the available experimental and theoretical data. Very good agreement between experimental and theoretical third-order elastic constant data (except C{sub 123}) is found. We have also computed the values of the pressure derivatives of second-order elastic constants and Anderson-Grueneisen parameter for alkali halides, which agree reasonably well with the experimental values, indicating the satisfactory nature of our computed data for third-order elastic constants.

  19. Third-order elastic moduli for alkali-halide crystals possessing the sodium chloride structure

    International Nuclear Information System (INIS)

    The values of third-order elastic moduli for alkali halides, having NaCl-type crystal structure are calculated according to the Born-Mayer potential model, considering the repulsive interactions up to the second nearest neighbours and calculating the values of the potential parameters for each crystal, independently, from the compressibility data. This work presents the first published account of the calculation of the third-order elastic moduli taking the actual value of the potential parameter unlike the earlier works. Third-order elastic constants have been computed for alkali halides at 0 and 300 K. The results of the third-order elastic constants are compared with the available experimental and theoretical data. Very good agreement between experimental and theoretical third-order elastic constant data (except C123) is found. We have also computed the values of the pressure derivatives of second-order elastic constants and Anderson-Grueneisen parameter for alkali halides, which agree reasonably well with the experimental values, indicating the satisfactory nature of our computed data for third-order elastic constants.

  20. Cesium Lead Halide Perovskites with Improved Stability for Tandem Solar Cells.

    Science.gov (United States)

    Beal, Rachel E; Slotcavage, Daniel J; Leijtens, Tomas; Bowring, Andrea R; Belisle, Rebecca A; Nguyen, William H; Burkhard, George F; Hoke, Eric T; McGehee, Michael D

    2016-03-01

    A semiconductor that can be processed on a large scale with a bandgap around 1.8 eV could enable the manufacture of highly efficient low cost double-junction solar cells on crystalline Si. Solution-processable organic-inorganic halide perovskites have recently generated considerable excitement as absorbers in single-junction solar cells, and though it is possible to tune the bandgap of (CH3NH3)Pb(BrxI1-x)3 between 2.3 and 1.6 eV by controlling the halide concentration, optical instability due to photoinduced phase segregation limits the voltage that can be extracted from compositions with appropriate bandgaps for tandem applications. Moreover, these materials have been shown to suffer from thermal degradation at temperatures within the processing and operational window. By replacing the volatile methylammonium cation with cesium, it is possible to synthesize a mixed halide absorber material with improved optical and thermal stability, a stabilized photoconversion efficiency of 6.5%, and a bandgap of 1.9 eV. PMID:26863290

  1. Lanthanum halide scintillators for time-of-flight 3-D pet

    Science.gov (United States)

    Karp, Joel S.; Surti, Suleman

    2008-06-03

    A Lanthanum Halide scintillator (for example LaCl.sub.3 and LaBr.sub.3) with fast decay time and good timing resolution, as well as high light output and good energy resolution, is used in the design of a PET scanner. The PET scanner includes a cavity for accepting a patient and a plurality of PET detector modules arranged in an approximately cylindrical configuration about the cavity. Each PET detector includes a Lanthanum Halide scintillator having a plurality of Lanthanum Halide crystals, a light guide, and a plurality of photomultiplier tubes arranged respectively peripherally around the cavity. The good timing resolution enables a time-of-flight (TOF) PET scanner to be developed that exhibits a reduction in noise propagation during image reconstruction and a gain in the signal-to-noise ratio. Such a PET scanner includes a time stamp circuit that records the time of receipt of gamma rays by respective PET detectors and provides timing data outputs that are provided to a processor that, in turn, calculates time-of-flight (TOF) of gamma rays through a patient in the cavity and uses the TOF of gamma rays in the reconstruction of images of the patient.

  2. First-principles study of γ-ray detector materials in perovskite halides

    Science.gov (United States)

    Im, Jino; Jin, Hosub; Stoumpos, Constantinos; Chung, Duck; Liu, Zhifu; Peters, John; Wessels, Bruce; Kanatzidis, Mercouri; Freeman, Arthur

    2013-03-01

    In an effort to search for good γ-ray detector materials, perovskite halide compounds containing heavy elements were investigated. Despite the three-dimensional network of the corner shared octahedra and the extended nature of the outermost shell, its strong ionic character leads to a large band gap, which is one of the essential criteria for γ-ray detector materials. Thus, considering high density and high atomic number, these pervoskite halides are possible candidate for γ-ray detector materials. We performed first-principles calculations to investigate electronic structures and thermodynamic properties of intrinsic defects in the selected perovskite halide, CsPbBr3. The screened-exchange local density approximation scheme was employed to correct the underestimation of the band gap in the LDA method. As a result, the calculated band gap of CsPbBr3 is found to be suitable for γ-ray detection. Furthermore, defect formation energy calculations allow us to predict thermodynamic and electronic properties of possible intrinsic defects, which affect detector efficiency and energy resolution. Supported by the office of Nonproliferation and Verification R &D under Contract No. DE-AC02-06CH11357

  3. Preparation of Polybutylene Oxides Bearing Terminal Ester Groups by Treatment of H[(CH_2)_4O]_nSiR_3 with Acyl Halides

    OpenAIRE

    Iura, Takafumi; Matsubara, Kouki; Nagashima,Hideo

    2000-01-01

    Treatment of H[(CH_2)_4O]_nSiR_3, which were prepared by the silane induced polymerization of THF with acyl halides catalyzed by (μ_3:η^2:η^3:η^5-acenaphthylene)Ru_3(CO)_7, provides a novel synthetic method for polybutylene oxides bearing terminal ester groups. Various acyl halides such as acetyl chloride, benzoyl bromide, adipoyl chloride, acryloyl chloride, and 2-bromoisobutyryl bromide could be used as the acyl halide component; the reactivity of acyl halides increased in the order RCOBr>R...

  4. Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

    OpenAIRE

    Samigullin, Dmitry; Fatikhov, Nijaz; Khaziev, Eduard; Skorinkin, Andrey; Nikolsky, Eugeny; Bukharaeva, Ellya

    2015-01-01

    At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dy...

  5. Variability of calcium absorption

    International Nuclear Information System (INIS)

    Variability in calcium absorption was estimated in three groups of normal subjects in whom Ca absorption was measured by standard isotopic-tracer methods at interstudy intervals ranging from 1 to 4 mo. Fifty absorption tests were performed in 22 subjects. Each was done in the morning after an overnight fast with an identical standard breakfast containing a Ca load of approximately 250 mg. Individual fractional absorption values were normalized to permit pooling of the data. The coefficient of variation (CVs) for absorption for the three groups ranged from 10.57 to 12.79% with the size of the CV increasing with interstudy duration. One other published study presenting replicate absorption values was analyzed in a similar fashion and was found to have a CV of absorption of 9.78%. From these data we estimate that when the standard double-isotope method is used to measure Ca absorption there is approximately 10% variability around any given absorption value within an individual human subject and that roughly two-thirds of this represents real biological variability in absorption

  6. Vibrational spectra of discrete UO22+ halide complexes in the gas phase

    International Nuclear Information System (INIS)

    The intrinsic binding of halide ions to the metal center in the uranyl molecule is a topic of ongoing research interest in both the actinide separations and theoretical communities. Investigations of structure in the condensed phases is frequently obfuscated by solvent interactions, that can alter ligand binding and spectroscopic properties. The approach taken in this study is to move the uranyl halide complexes into the gas phase where they are free from solvent interactions, and then interrogate their vibrational spectroscopy using infrared multiple photon dissociation (IRMPD). The spectra of cationic coordination complexes having the composition (UO2(X)(ACO)3)+ (X = F, Cl, Br and I; ACO = acetone) were acquired using electrospray for ion formation, and monitoring the ion signal from the photoelimination of ACO ligands. The studies showed that the asymmetric v3 UO2 frequency was insensitive to halide identity as X was varied from Cl to I, suggesting that in these pseudo octahedral complexes, changing the nucleophilicity of the halide did not appreciably alter the binding in the complex. The v3 peak in the spectrum of the F-containing complex was ∼ 10 cm-1 lower indicating stronger coordination in this complex. Similarly the ACO carbonyl stretches showed that the C=O frequency was relatively insensitive to the identity of the halide, although a modest shift to the blue was seen for the complexes with the more nucleophilic anions, consistent with the idea that they loosen solvent binding. Surprisingly, the v1 stretch was activated when the softer anions Cl, Br and I were present in the complexes. IR studies of the anionic complexes were conducted by measuring the v3 UO2 frequencies of (UO2X3)-, where X = Cl-, Br- and I-. The trifluoro complex could not be photodissociated. In these negatively charged complexes, the UO2 v3 values decreased with increasing anion nucleophilicity. This observation was consistent with DFT calculations that indicated that dissociation

  7. Possibility of elastico-mechanoluminescence dosimetry using alkali halides and other crystals

    International Nuclear Information System (INIS)

    The elastico-mechanoluminescence (EML) intensity of X or γ-irradiated alkali halide crystals can be used in radiation dosimetry. The EML intensity of X or γ-irradiated alkali halide crystals increases linearly with the strain of the crystals, and when the crosshead of the testing machine deforming an X or γ-irradiated crystal is stopped, then the EML intensity decreases with time. The semilog plot of the EML intensity versus (t − tc) (where tc is the time where the crosshead of the testing machine is stopped) indicates that, in the post-deformation region, the EML intensity initially decreases exponentially at a fast rate and later on it decreases exponentially at a slow rate. The EML intensity increases linearly with the density of the F-centres in the crystals. This fact indicates that elastico-ML can suitably be used for the radiation dosimetry. The EML spectra of X or γ-irradiated alkali halide crystals are similar to their thermoluminescence spectra. Based on the detrapping of electrons during the mechanical interaction between the dislocation segments and F-centres, an expression is derived, which indicates that the EML intensity should increase linearly with the density of F-centres in the crystals. The expression derived for the decay of EML indicates that the decay time for the fast decrease of EML should gives the pinning time of dislocation segments (lifetime of interacting F-centres), and the decay time for the slow decrease of EML intensity should gives the lifetime of electrons in the shallow traps. As the elastic deformation is non-destructive phenomenon and the EML intensity depends on the radiation dosage given to the alkali halide crystals, similar to the thermoluminescence and photo-stimulated luminescence, the EML of alkali halide crystals and other crystals may be used for the radiation dosimetry. In EML dosimetry, the same crystal can be used number of times because the elastic deformation does not cause permanent deformation in the

  8. Calcium-sensitive immunoaffinity chromatography

    DEFF Research Database (Denmark)

    Henriksen, Maiken L; Lindhardt Madsen, Kirstine; Skjoedt, Karsten;

    2014-01-01

    homogeneity may be impossible due to contamination with abundant antigens. In this study, we purified the scarce, complement-associated plasma protein complex, collectin LK (CL-LK, complex of collectin liver 1 and kidney 1), by immunoaffinity chromatography using a calcium-sensitive anti-collectin-kidney-1 m......Ab. This antibody was characterized by binding to CL-LK at hypo- and physiological calcium concentrations and dissociated from CK-LK at hyperphysiological concentrations of calcium. We purified CL-LK from plasma to a purity of 41% and a yield of 38%, resulting in a purification factor of more than 88......,000 in a single step. To evaluate the efficiency of this new purification scheme, we purified CL-LK using the same calcium-sensitive mAb in combination with acidic elution buffer and by using calcium-dependent anti-CL-K1 mAbs in combination with EDTA elution buffer. We found that calcium...

  9. Experimental observations on the competing effect of tetrahydrofuran and an electrolyte and the strength of hydrate inhibition among metal halides in mixed CO{sub 2} hydrate equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Sabil, Khalik M., E-mail: khalik_msabil@petronas.com.m [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Universiti Teknologi PETRONAS, Chemical Engineering Programme, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Roman, Vicente R.; Witkamp, Geert-Jan [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Peters, Cor J., E-mail: C.J.Peters@tudelft.n [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Petroleum Institute, Chemical Engineering Program, Bu Hasa Building, Room 2207A, P.O. Box 2533, Abu Dhabi (United Arab Emirates)

    2010-03-15

    In the present work, experimental data on the equilibrium conditions of mixed CO{sub 2} and THF hydrates in aqueous electrolyte solutions are reported. Seven different electrolytes (metal halides) were used in this work namely sodium chloride (NaCl), calcium chloride (CaCl{sub 2}), magnesium chloride (MgCl{sub 2}), potassium bromide (KBr), sodium fluoride (NaF), potassium chloride (KCl), and sodium bromide (NaBr). All equilibrium data were measured by using Cailletet apparatus. Throughout this work, the overall concentration of CO{sub 2} and THF were kept constant at (0.04 and 0.05) mol fraction, respectively, while the concentration of electrolytes were varied. The experimental temperature ranged from (275 to 305) K and pressure up 7.10 MPa had been applied. From the experimental results, it is concluded that THF, which is soluble in water is able to suppress the salt inhibiting effect in the range studied. In all quaternary systems studied, a four-phase hydrate equilibrium line was observed where hydrate (H), liquid water (L{sub W}), liquid organic (L{sub V}), and vapour (V) exist simultaneously at specific pressure and temperature. The formation of this four-phase equilibrium line is mainly due to a liquid-liquid phase split of (water + THF) mixture when pressurized with CO{sub 2} and the split is enhanced by the salting-out effect of the electrolytes in the quaternary system. The strength of hydrate inhibition effect among the electrolytes was compared. The results shows the hydrate inhibiting effect of the metal halides is increasing in the order NaF < KBr < NaCl < NaBr < CaCl{sub 2} < MgCl{sub 2}. Among the cations studied, the strength of hydrate inhibition increases in the following order: K{sup +} < Na{sup +} < Ca{sup 2+} < Mg{sup 2+}. Meanwhile, the strength of hydrate inhibition among the halogen anion studied decreases in the following order: Br{sup -} > Cl{sup -} > F{sup -}. Based on the results, it is suggested that the probability of formation and

  10. Inhibition of mild steel corrosion in acidic medium using synthetic and naturally occurring polymers and synergistic halide additives

    Energy Technology Data Exchange (ETDEWEB)

    Umoren, S.A. [Department of Chemistry, Faculty of Science, University of Uyo, P.M.B 1017 Uyo (Nigeria)], E-mail: saviourumoren@yahoo.com; Ogbobe, O.; Igwe, I.O. [Department of Polymer and Textile Engineering, School of Engineering and Engineering Technology, Federal University of Technology, P.M.B. 1526 Owerri (Nigeria); Ebenso, E.E. [Department of Chemistry and Chemical Technology, National University of Lesotho, P. O. Roma180, Lesotho (South Africa)

    2008-07-15

    The corrosion inhibition of mild steel in H{sub 2}SO{sub 4} in the presence of gum arabic (GA) (naturally occurring polymer) and polyethylene glycol (PEG) (synthetic polymer) was studied using weight loss, hydrogen evolution and thermometric methods at 30-60 deg. C. PEG was found to be a better inhibitor for mild steel corrosion in acidic medium than GA. The effect of addition of halides (KCl, KBr and KI) was also studied. Results obtained showed that inhibition efficiency (I%) increased with increase in GA and PEG concentration, addition of halides and with increase in temperature. Increase in inhibition efficiency (I%) and degree of surface coverage ({theta}) was found to follow the trend Cl{sup -} < Br{sup -} < I{sup -} which indicates that the radii and electronegativity of the halide ions play a significant role in the adsorption process. GA and PEG alone and in combination with halides were found to obey Temkin adsorption isotherm. Phenomenon of chemical adsorption is proposed from the trend of inhibition efficiency with temperature and values {delta}G{sub ads}{sup 0} obtained. The synergism parameter, S{sub I} evaluated is found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is only due to synergism.

  11. "Caged calcium" in Aplysia pacemaker neurons. Characterization of calcium-activated potassium and nonspecific cation currents

    OpenAIRE

    1989-01-01

    We have studied calcium-activated potassium current, IK(Ca), and calcium-activated nonspecific cation current, INS(Ca), in Aplysia bursting pacemaker neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium" intracellularly. A computer model of nitr photolysis, multiple buffer equilibration, and active calcium extrusion was developed to predict volume-average and front-surface calcium concentration transients. Changes in arsenazo III absorbance were used to...

  12. Effect of Preharvest Calcium Treatments on Sweet Cherry Fruit Quality

    OpenAIRE

    Deniz EROGUL

    2014-01-01

    In this study, the effects of different foliar calcium compounds on fruit cracking and quality of sweet cherry variety ‘0900 Ziraat’ were investigated. Calcium caseinate, calcium chloride, calcium hydroxide and calcium nitrate were used as foliar sprays. Calcium applications reduced the cracking index 38% to 66% compared to cherries that did not receive foliar treatment. The most efficient applications for decreasing cracking were calcium hydroxide and calcium chloride. Calcium chloride and c...

  13. Stochastic Simulation of Cardiac Ventricular Myocyte Calcium Dynamics and Waves

    OpenAIRE

    Tuan, Hoang-Trong Minh; Williams, George S.B.; Chikando, Aristide C.; Sobie, Eric A.; Lederer, W. Jonathan; Jafri, M. Saleet

    2011-01-01

    A three dimensional model of calcium dynamics in the rat ventricular myocyte was developed to study the mechanism of calcium homeostasis and pathological calcium dynamics during calcium overload. The model contains 20,000 calcium release units (CRUs) each containing 49 ryanodine receptors. The model simulates calcium sparks with a realistic spontaneous calcium spark rate. It suggests that in addition to the calcium spark-based leak, there is an invisible calcium leak caused by the stochastic ...

  14. Aging and calcium as an environmental factor.

    Science.gov (United States)

    Fujita, T

    1985-12-01

    Calcium deficiency is a constant menace to land-abiding animals, including mammals. Humans enjoying exceptional longevity on earth are especially susceptible to calcium deficiency in old age. Low calcium and vitamin D intake, short solar exposure, decreased intestinal absorption, and falling renal function with insufficient 1,25(OH)2 vitamin D biosynthesis all contribute to calcium deficiency, secondary hyperparathyroidism, bone loss and possibly calcium shift from the bone to soft tissue, and from the extracellular to the intracellular compartment, blunting the sharp concentration gap between these compartments. The consequences of calcium deficiency might thus include not only osteoporosis, but also arteriosclerosis and hypertension due to the increase of calcium in the vascular wall, amyotrophic lateral sclerosis and senile dementia due to calcium deposition in the central nervous system, and a decrease in cellular function, because of blunting of the difference in extracellular-intracellular calcium, leading to diabetes mellitus, immune deficiency and others (Fig. 6). PMID:2943880

  15. Transport of Calcium Ions into Mitochondria.

    Science.gov (United States)

    Xu, Zhaolong; Zhang, Dayong; He, Xiaolan; Huang, Yihong; Shao, Hongbo

    2016-06-01

    To uptake calcium ions of mitochondria is of significant functional connotation for cells, because calcium ions in mitochondria are involved in energy production, regulatory signals transfer, and mitochondrial permeability transition pore opening and even programmed cell death of apoptosis, further playing more roles in plant productivity and quality. Cytoplasmic calcium ions access into outer mitochondrial membrane (OMM) from voltage dependent anion-selective channel (VDAC) and were absorbed into inner mitochondrial membrane (IMM) by mitochondrial calcium uniporter (MCU), rapid mitochondrial calcium uptake (RaM) or mitochondrial ryanodine receptor (mRyR). Although both mitochondria and the mechanisms of calcium transport have been extensively studied, but there are still long-standing or even new challenges. Here we review the history and recent discoveries of the mitochondria calcium ions channel complex involved calcium assimilation, and discuss the role of calcium ions into mitochondria. PMID:27252588

  16. Optimizing calcium selective fluorimetric nanospheres.

    Science.gov (United States)

    Kisiel, Anna; Kłucińska, Katarzyna; Gniadek, Marianna; Maksymiuk, Krzysztof; Michalska, Agata

    2015-11-01

    Recently it was shown that optical nanosensors based on alternating polymers e.g. poly(maleic anhydride-alt-1-octadecene) were characterized by a linear dependence of emission intensity on logarithm of concentration over a few of orders of magnitude range. In this work we focus on the material used to prepare calcium selective nanosensors. It is shown that alternating polymer nanosensors offer competitive performance in the absence of calcium ionophore, due to interaction of the nanospheres building blocks with analyte ions. The emission increase corresponds to increase of calcium ions contents in the sample within the range from 10(-4) to 10(-1) M. Further improvement in sensitivity (from 10(-6) to 10(-1) M) and selectivity can be achieved by incorporating calcium ionophore in the nanospheres. The optimal results were obtained for core-shell nanospheres, where the core was prepared from poly(styrene-co-maleic anhydride) and the outer layer from poly(maleic anhydride-alt-1-octadecene). Thus obtained chemosensors were showing linear dependence of emission on logarithm of calcium ions concentration within the range from 10(-7) to 10(-1) M. PMID:26452839

  17. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    International Nuclear Information System (INIS)

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca9Sr(PO4)6(OH)2 - CaSr9(PO4)6(OH)2. The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice

  18. 40 CFR Table 3 to Subpart Ffff of... - Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP Metals Emissions From...

    Science.gov (United States)

    2010-07-01

    ... Halogen HAP Emissions or HAP Metals Emissions From Process Vents 3 Table 3 to Subpart FFFF of Part 63... to Subpart FFFF of Part 63—Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP... following table that applies to your process vents that contain hydrogen halide and halogen HAP emissions...

  19. Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

    OpenAIRE

    Ueda, Yukari; Taira, Zenei

    2013-01-01

    We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 mg/kg, and is not affected by anions. Results after oral calcium administration of 150 mg/kg showed that the intes...

  20. Calcium release-activated calcium current in rat mast cells.

    Science.gov (United States)

    Hoth, M; Penner, R

    1993-06-01

    1. Whole-cell patch clamp recordings of membrane currents and fura-2 measurements of free intracellular calcium concentration ([Ca2+]i) were used to study the biophysical properties of a calcium current activated by depletion of intracellular calcium stores in rat peritoneal mast cells. 2. Calcium influx through an inward calcium release-activated calcium current (ICRAC) was induced by three independent mechanisms that result in store depletion: intracellular infusion of inositol 1,4,5-trisphosphate (InsP3) or extracellular application of ionomycin (active depletion), and intracellular infusion of calcium chelators (ethylene glycol bis-N,N,N',N'-tetraacetic acid (EGTA) or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA)) to prevent reuptake of leaked-out calcium into the stores (passive depletion). 3. The activation of ICRAC induced by active store depletion has a short delay (4-14 s) following intracellular infusion of InsP3 or extracellular application of ionomycin. It has a monoexponential time course with a time constant of 20-30 s and, depending on the complementary Ca2+ buffer, a mean normalized amplitude (at 0 mV) of 0.6 pA pF-1 (with EGTA) and 1.1 pA pF-1 (with BAPTA). 4. After full activation of ICRAC by InsP3 in the presence of EGTA (10 mM), hyperpolarizing pulses to -100 mV induced an instantaneous inward current that decayed by 64% within 50 ms. This inactivation is probably mediated by [Ca2+]i, since the decrease of inward current in the presence of the fast Ca2+ buffer BAPTA (10 mM) was only 30%. 5. The amplitude of ICRAC was dependent on the extracellular Ca2+ concentration with an apparent dissociation constant (KD) of 3.3 mM. Inward currents were nonsaturating up to -200 mV. 6. The selectivity of ICRAC for Ca2+ was assessed by using fura-2 as the dominant intracellular buffer (at a concentration of 2 mM) and relating the absolute changes in the calcium-sensitive fluorescence (390 nm excitation) with the calcium current integral

  1. Fine structures in the optical absorption spectra of photochemical silver in silver halides? A call for further research

    CERN Document Server

    Georgiev, Mladen

    2007-01-01

    A survey is presented of the work done so far to check earlier claims that a fine structure may be observed to occur under certain circumstances in the impurity spectral range of the optical absorption spectra of silver halides following photostimulation in the intrinsic range. This structure, associated with the photochemical formation of silver specks, has been questioned over the years. We now weigh carefully the experimental evidence on the silver halides against a background of similar data on the alkali halides, where competing processes run slower. We come to the conclusion that present day advances in experimental techniques may be quite adequate for providing a solid experimental basis to solve the problem unambiguously.

  2. Calcium phosphate in catheter encrustation.

    Science.gov (United States)

    Cox, A J; Harries, J E; Hukins, D W; Kennedy, A P; Sutton, T M

    1987-02-01

    Encrusted catheters from nine female patients were the source of samples of deposits which were examined by X-ray diffraction, atomic absorption spectroscopy, infra-red spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. In eight samples the only crystalline phase which could be clearly distinguished by X-ray diffraction was ammonium magnesium orthophosphate hexahydrate, NH4MgPO4 X 6H2O, which occurs naturally as the mineral struvite. However, atomic absorption spectroscopy revealed an appreciable concentration of calcium in all samples. Calcium phosphates have previously been detected in catheter deposits. Infra-red and EXAFS spectra were consistent with the calcium phosphate being present as a poorly crystalline hydroxyapatite. Thus the deposits appear to consist of a mixture of crystalline struvite and a form of hydroxyapatite which is not fully crystalline. PMID:3030487

  3. Mass and orientation effects in dissociative collisions between rare gas atoms and alkali halide molecules

    International Nuclear Information System (INIS)

    The collision induced dissociation of alkali halide molecules to ion pairs upon impact with hyperthermal rare gas atoms has been investigated using the crossed molecular beam method. Relative total cross sections for the dissociation of CsI, CsBr, RbI, and KI to ion pairs upon collision with xenon and krypton have been measured over a relative collision energy range from threshold to 10 and 8 eV, respectively. In addition, complete angular and energy distributions of both dissociated ions from Xe+CsI, CsBr, and RbI collisions and from Kr+CsI and CsBr collisions have been obtained at several collision energies within the above energy range. Mass, collision orientation, and energy dependence effects observed throughout this work define two limiting case dissociation mechanisms for the Xe(Kr)+MX→Xe(Kr)+M++X- processes. The dominant dissociation configuration consists of the rare gas atom incident on the light atom end of the alkali halide molecule in a near collinear collision. The less preferred dissociation mechanism results when the rare gas atom is incident in a near collinear configuration on the heavy atom end of the alkali halide molecule. Experimental measurements of the percentage of energy transfer from the relative kinetic energy between Xe(Kr) and MX to the relative motion of M+--X- range as high as 95%; these percentage energy transfers correlate well with the predictions of an impulsive collision model. Three-dimensional classical trajectory calculations using realistic interaction potentials have been performed and they verify the dynamical interpretation suggested by the experiments

  4. Metallaphotoredox-catalysed sp(3)-sp(3) cross-coupling of carboxylic acids with alkyl halides.

    Science.gov (United States)

    Johnston, Craig P; Smith, Russell T; Allmendinger, Simon; MacMillan, David W C

    2016-08-18

    In the past 50 years, cross-coupling reactions mediated by transition metals have changed the way in which complex organic molecules are synthesized. The predictable and chemoselective nature of these transformations has led to their widespread adoption across many areas of chemical research. However, the construction of a bond between two sp(3)-hybridized carbon atoms, a fundamental unit of organic chemistry, remains an important yet elusive objective for engineering cross-coupling reactions. In comparison to related procedures with sp(2)-hybridized species, the development of methods for sp(3)-sp(3) bond formation via transition metal catalysis has been hampered historically by deleterious side-reactions, such as β-hydride elimination with palladium catalysis or the reluctance of alkyl halides to undergo oxidative addition. To address this issue, nickel-catalysed cross-coupling processes can be used to form sp(3)-sp(3) bonds that utilize organometallic nucleophiles and alkyl electrophiles. In particular, the coupling of alkyl halides with pre-generated organozinc, Grignard and organoborane species has been used to furnish diverse molecular structures. However, the manipulations required to produce these activated structures is inefficient, leading to poor step- and atom-economies. Moreover, the operational difficulties associated with making and using these reactive coupling partners, and preserving them through a synthetic sequence, has hindered their widespread adoption. A generically useful sp(3)-sp(3) coupling technology that uses bench-stable, native organic functional groups, without the need for pre-functionalization or substrate derivatization, would therefore be valuable. Here we demonstrate that the synergistic merger of photoredox and nickel catalysis enables the direct formation of sp(3)-sp(3) bonds using only simple carboxylic acids and alkyl halides as the nucleophilic and electrophilic coupling partners, respectively. This metallaphotoredox

  5. Solvation structure of the halides from x-ray absorption spectroscopy

    Science.gov (United States)

    Antalek, Matthew; Pace, Elisabetta; Hedman, Britt; Hodgson, Keith O.; Chillemi, Giovanni; Benfatto, Maurizio; Sarangi, Ritimukta; Frank, Patrick

    2016-07-01

    Three-dimensional models for the aqueous solvation structures of chloride, bromide, and iodide are reported. K-edge extended X-ray absorption fine structure (EXAFS) and Minuit X-ray absorption near edge (MXAN) analyses found well-defined single shell solvation spheres for bromide and iodide. However, dissolved chloride proved structurally distinct, with two solvation shells needed to explain its strikingly different X-ray absorption near edge structure (XANES) spectrum. Final solvation models were as follows: iodide, 8 water molecules at 3.60 ± 0.13 Å and bromide, 8 water molecules at 3.40 ± 0.14 Å, while chloride solvation included 7 water molecules at 3.15 ± 0.10 Å, and a second shell of 7 water molecules at 4.14 ± 0.30 Å. Each of the three derived solvation shells is approximately uniformly disposed about the halides, with no global asymmetry. Time-dependent density functional theory calculations simulating the chloride XANES spectra following from alternative solvation spheres revealed surprising sensitivity of the electronic state to 6-, 7-, or 8-coordination, implying a strongly bounded phase space for the correct structure during an MXAN fit. MXAN analysis further showed that the asymmetric solvation predicted from molecular dynamics simulations using halide polarization can play no significant part in bulk solvation. Classical molecular dynamics used to explore chloride solvation found a 7-water solvation shell at 3.12 (-0.04/+0.3) Å, supporting the experimental result. These experiments provide the first fully three-dimensional structures presenting to atomic resolution the aqueous solvation spheres of the larger halide ions.

  6. Monitoring of heavy/toxic metals and halides in surface/ground water (abstract)

    International Nuclear Information System (INIS)

    Water is essential for maintaining physical and social life. Human and animal consumption is perhaps the most evident essential use of water. Water quality and quantity have become critical issues, affecting all life. The importance of water in our lives, combined with the threats, make water resources use a global problem. Among the different pollutants toxic metals, metalloids and halides have special significance. Industrial effluents and municipal wastewater are normally drained into water streams, rivers and other reservoirs thus polluting these significantly. Quality of our water resources especially is an issue, which continues to arouse the attention of concerned scientists, legislators and the general public. Among various pollutant chemicals, the heavy metals and metalloids are present at trace levels in various compartments of the environment. Some metals become toxic even at trace levels because of the important features that distinguishes metals from other pollutants is that they are not biodegradable. The halides like Cl, Br, and I from different sources can enter easily into water systems and then they make their way directly into the human body. The intake of toxic as wells as essential elements through water and other food items like vegetables, milk wheat flour etc. is significant. The abundance or deficiency of these meals as well as halides results in abnormal metabolic functions. Due to excessive demand for trace analysis in water and other materials a variety of techniques and instrumentation has been developed. Determination of heavy metals ions is of the highest interest in environmental analysis. Among the food materials water is most important because of their large consumption by man. Also toxic metals in water may be in dissolved ionic form, which directly go into human metabolism and start their toxic action. Presence of even small amounts of toxic metals in drinking water can produce serious health hazards. (author)

  7. Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

    Science.gov (United States)

    Kuzmina, O; Bordes, E; Schmauck, J; Hunt, P A; Hallett, J P; Welton, T

    2016-06-28

    The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids. PMID:27264676

  8. The effect of variable calcium and very low calcium diets on human calcium metabolism. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Chu, J.

    1971-01-01

    The effects of a very low calcium diet, with variable high and low protein intake, on the dynamics of calcium metabolism and the mechanism of calciuretics, are examined. The experiment, using male subjects, was designed to study the role of intestinal calcium absorption on urinary calcium excretion, and the rate of production of endogeneously secreted calcium in the gastrointestinal tract. The study showed an average of 70% fractional absorption rate during very low calcium intake, and that a decrease in renal tubular reabsorption of calcium is responsible for calciuretic effects of high protein intake. The study also indicates that there is a tendency to develop osteoporosis after long periods of low calcium intake, especially with a concurrent high protein intake.

  9. A First-Principles Study on the Structural and Electronic Properties of Sn-Based Organic-Inorganic Halide Perovskites

    Science.gov (United States)

    Ma, Zi-Qian; Pan, Hui; Wong, Pak Kin

    2016-08-01

    Organic-inorganic halide perovskites have attracted increasing interest on solar-energy harvesting because of their outstanding electronic properties. In this work, we systematically investigate the structural and electronic properties of Sn-based hybrid perovskites MASnX3 and FASnX3 (X = I, Br) based on density-functional-theory calculations. We find that their electronic properties strongly depend on the organic molecules, halide atoms, and structures. We show that there is a general rule to predict the band gap of the Sn-based hybrid perovskite: its band gap increases as the size of halide atom decreases as well as that of organic molecule increase. The band gap of high temperature phase (cubic structure) is smaller than that of low temperature phase (orthorhombic structure). The band gap of tetragonal structure (medium-temperature phase) may be larger or smaller than that of cubic phase, depending on the orientation of the molecule. Tunable band gap within a range of 0.73-1.53 eV can be achieved by choosing halide atom and organic molecule, and controlling structure. We further show that carrier effective mass also reduces as the size of halide atom increases and that of molecule decreases. By comparing with Pb-based hybrid perovskites, the Sn-based systems show enhanced visible-light absorption and carrier mobility due to narrowed band gap and reduced carrier effective mass. These Sn-based organic-inorganic halide perovskites may find applications in solar energy harvesting with improved performance.

  10. Measurements of prompt fission gamma-rays and neutrons with lanthanide halide scintillation detectors

    CERN Document Server

    Oberstedt, A; Billnert, R; Borcea, R; Brys, T; Chaves, C; Gamboni, T; Geerts, W; Göök, A; Guerrero, C; Hambsch, F-J; Kis, Z; Martinez, T; Oberstedt, S; Szentmiklosi, L; Takács, K; Vivaldi, M

    2014-01-01

    Photons have been measured with lanthanide halide scintillation detectors in coincidence with fission fragments. Using the time-of-flight information, reactions from γ-rays and neutrons could easily be distinguished. In several experiments on $^{252}$Cf(sf), $^{235}$U(n$_{th}$,f) and $^{241}$Pu(n$_{th}$,f) prompt fission γ-ray spectra characteristics were determined with high precision and the results are presented here. Moreover, a measured prompt fission neutron spectrum for $^{235}$U(n$_{th}$,f) is shown in order to demonstrate a new detection technique.

  11. Solvated Positron Chemistry - Positron Reactions with Pseudo-Halide Ions in Water

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Pedersen, Niels Jørgen; Andersen, Jan Rud

    1982-01-01

    The hydrated positron e+aq reactions with SCN−, OCN−, CN−, S2− were studied by means of the angular correlation technique. The positron forms bound states with SCN−, CN−, and S2− but not with OCN−. Apparently, the e+aq reaction with SH− results in a positron bound state with S2−. It was difficult...... to determine the shapes of the bound-state angular correlation curves. Only in the SCN− case could a very rough estimate of the rate constant be obtained. Estimates of the binding energies relative to those of the corresponding halide ion states could be determined for SCN− and S2−....

  12. Organic-inorganic interactions of single crystalline organolead halide perovskites studied by Raman spectroscopy.

    Science.gov (United States)

    Xie, Li-Qiang; Zhang, Tai-Yang; Chen, Liang; Guo, Nanjie; Wang, Yu; Liu, Guo-Kun; Wang, Jia-Rui; Zhou, Jian-Zhang; Yan, Jia-Wei; Zhao, Yi-Xin; Mao, Bing-Wei; Tian, Zhong-Qun

    2016-07-21

    Organolead halide perovskites exhibit superior photoelectric properties, which have given rise to the perovskite-based solar cells whose power conversion efficiency has rapidly reached above 20% in the past few years. However, perovskite-based solar cells have also encountered problems such as current-voltage hysteresis and degradation under practical working conditions. Yet investigations into the intrinsic chemical nature of the perovskite material and its role on the performance of the solar cells are relatively rare. In this work, Raman spectroscopy is employed together with CASTEP calculations to investigate the organic-inorganic interactions in CH3NH3PbI3 and CH3NH3PbBr3-xClx perovskite single crystals with comparison to those having ammonic acid as the cations. For Raman measurements of CH3NH3PbI3, a low energy line of 1030 nm is used to avoid excitation of strong photoluminescence of CH3NH3PbI3. Raman spectra covering a wide range of wavenumbers are obtained, and the restricted rotation modes of CH3-NH3(+) embedded in CH3NH3PbBr3 (325 cm(-1)) are overwhelmingly stronger over the other vibrational bands of the cations. However, the band intensity diminishes dramatically in CH3NH3PbBr3-xClx and most of the bands shift towards high frequency, indicating the interaction with the halides. The details of such an interaction are further revealed by inspecting the band shift of the restricted rotation mode as well as the C-N, NH3(+) and CH3 stretching of the CH3NH3(+) as a function of Cl composition and length of the cationic ammonic acids. The results show that the CH3NH3(+) interacts with the PbX3(-) octahedral framework via the NH3(+) end through N(+)-HX hydrogen bonding whose strength can be tuned by the composition of halides but is insensitive to the size of the organic cations. Moreover, an increase of the Cl content strengthens the hydrogen bonding and thus blueshifts the C-N stretching bands. This is due to the fact that Cl is more electronegative than Br

  13. Nickel-Catalyzed Methylation of Aryl Halides with Deuterated Methyl Iodide.

    Science.gov (United States)

    Hu, Lu; Liu, Xin; Liao, Xuebin

    2016-08-01

    A nickel-catalyzed methylation of aryl halides with cheap and readily available CH3 I or CD3 I is described. The reaction is applicable to a wide range of substrates and allows installation of a CD3 group under mild reaction conditions without deuterium scrambling to other carbon atoms. Initial mechanistic studies on the stoichiometric and catalytic reactions of the isolated [(dppp)Ni(C6 H4 -4-CO2 Et)Br] [dppp=1,3-bis(diphenylphosphanyl)propane] suggest that a Ni(0) /Ni(II) catalytic cycle is favored. PMID:27381725

  14. The super-super exchange mechanism in iron-based antiperovskite chalco-halides

    OpenAIRE

    Liu, Kai; LU, Zhong-Yi

    2016-01-01

    By using the first-principles electronic structure calculations, we have systematically studied the magnetism in three recently synthesized iron-based antiperovskite chalco-halides: Ba$_3$(FeS$_4$)Cl, Ba$_3$(FeS$_4$)Br, and Ba$_3$(FeSe$_4$)Br. These compounds consist of edge-sharing Ba$Q_6$ ($Q$=Cl or Br) octahedra intercalated with isolated Fe$X_4$ ($X$=S or Se) tetrahedra. We find that even though the shortest distances between the nearest-neighboring Fe atoms in these three compounds alrea...

  15. High-Pressure Low-Symmetry Phases of Cesium Halides from First Principle Techniques

    OpenAIRE

    Nardelli, M. Buongiorno; Baroni, S.; Giannozzi, P.

    1994-01-01

    The relative stability of different high-pressure phases of various Cesium Halides is studied from first principles and analyzed using the Landau theory of phase transitions. We present results for CsI, CsBr, and CsCl up to pressures of about 100 GPa. A cubic-to-orthorhombic transition, driven by the softening of an acoustic phonon at the M point of the Brillouin zone, is competing with the cubic-to-tetragonal martensitic transition typical of these compounds. The phonon softening takes place...

  16. Methyl halides in surface seawater and marine boundary layer of the northwest Pacific

    OpenAIRE

    Ooki, Atsushi; Tsuda, Atsushi; Kameyama, Sohiko; Takeda, Shigenobu; Itoh, Sachihiko; SUGA, Toshio; Tazoe, Hirofumi; Okubo, Ayako; Yokouchi, Yoko

    2010-01-01

    The partial pressures of methyl halides (CH3X; X = Cl, Br, or I) and of CHClF2 (HCFC‐22), which are all volatile organic compounds (VOCs), were measured in the air of the marine boundary layer (pVOCair) and in surface seawater (pVOCwater) during a cruise from the subarctic to subtropical regions of the northwest Pacific in summer of 2008. In the northern transition water (TWN) with high biological activity, high levels of the three CH3Xs in surface seawater were frequently obse...

  17. Concentration Effects of Silver Ions on Ionic Conductivities of Molten Silver Halides

    OpenAIRE

    Okada T.; Kawakita Y.; Tahara S.; Ohno S.; Takeda S

    2011-01-01

    Ionic conductivities of molten (RbX)c(AgX)1-c (X = Cl and I) mixtures were measured to clarify the concentration effects of silver ions on ionic conductivities of molten silver halides. It is found that the addition of RbX to molten AgX rapidly reduces the ionic conductivity with 0 ≤ c ≤ 0.4. It suggests that strong Ag-Ag correlation is necessary to fast conduction of Ag ions in molten state. The absolute values of ionic conductivity for (RbCl)c(AgCl)1-c are larger than those for (R...

  18. Copper Complexes of Anionic Nitrogen Ligands in the Amidation and Imidation of Aryl Halides

    OpenAIRE

    Tye, Jesse W.; Weng, Zhiqiang; Johns, Adam M.; Incarvito, Christopher D.; Hartwig, John F.

    2008-01-01

    Copper(I) imidate and amidate complexes of chelating N,N-donor ligands, which are proposed intermediates in copper-catalyzed amidations of aryl halides, have been synthesized and characterized by X-ray diffraction and detailed solution-phase methods. In some cases, the complexes adopt neutral, three-coordinate trigonal planar structures in the solid state, but in other cases they adopt an ionic form consisting of an L2Cu+ cation and a CuX2− anion. A tetraalkylammonium salt of the CuX2− anion ...

  19. Physics and Nanofriction of Alkali Halide Solid Surfaces at the Melting Point

    OpenAIRE

    Zykova-Timan, T.; Ceresoli, D.; Tartaglino, U.; Tosatti, E.

    2006-01-01

    Alkali halide (100) surfaces are anomalously poorly wetted by their own melt at the triple point. We carried out simulations for NaCl(100) within a simple (BMHFT) model potential. Calculations of the solid-vapor, solid-liquid and liquid-vapor free energies showed that solid NaCl(100) is a nonmelting surface, and that the incomplete wetting can be traced to the conspiracy of three factors: surface anharmonicities stabilizing the solid surface; a large density jump causing bad liquid-solid adhe...

  20. Why Are Alkali Halide Solid Surfaces Not Wetted By Their Own Melt?

    OpenAIRE

    Zykova-Timan, T.; Ceresoli, D.; Tartaglino, U.; Tosatti, E.

    2005-01-01

    Alkali halide (100) crystal surfaces are anomalous, being very poorly wetted by their own melt at the triple point. We present extensive simulations for NaCl, followed by calculations of the solid-vapor, solid-liquid, and liquid-vapor free energies showing that solid NaCl(100) is a nonmelting surface, and that its full behavior can quantitatively be accounted for within a simple Born-Meyer-Huggins-Fumi-Tosi model potential. The incomplete wetting is traced to the conspiracy of three factors: ...

  1. Development and Application of TiO2 Nanoparticles Coupled with Silver Halide

    Directory of Open Access Journals (Sweden)

    Xiaojia Wan

    2014-01-01

    Full Text Available Titanium dioxide (TiO2 is proposed to be effective photocatalyst for wastewater treatment, air purification, and self-cleaning ability, because of its strong oxidation and superhydrophilicity. In order to conquer the limits of TiO2, a variety of methods have been used. This paper presents a critical review of novel research and achievements in the modification of TiO2 nanoparticles with silver halide (AgX, X=Cl, Br, I, which aims at enhancing the visible light absorption and photosensitivity. Herein we study the synthesis, physical and chemical properties, and the mechanism of this composite photocatalyst.

  2. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    Energy Technology Data Exchange (ETDEWEB)

    Selling, J.

    2007-07-01

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl{sub 2} nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI{sub 2} is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu{sup 2+}/Eu{sup 3+} ratio in the glass ceramics should be determined and optimize favor of the Eu{sup 2+}. We also want to distinguish between Eu{sup 2+} in the glass matrix and Eu{sup 2+} in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a

  3. Laser-synchrotron studies of the dynamics of UV-photon-stimulated desorption in alkali halides

    International Nuclear Information System (INIS)

    Laser-synchrotron studies of neutral alkali emission from alkali halide crystals are yielding new insights into the dynamics of energy absorption, energy localization and bond-breaking in photon-stimulated desorption. The ground-state neutral desorption is triggered by the thermal diffusion of photon-induced electronic defects; however, the excited-state neutral alkalis are formed in a surface-specific process on an extremely short time scale. In addition, there is new evidence for a surface overlayer which retards substrate desorption, thus suggesting a new approach to the optical damage problem at ultraviolet wavelengths. 8 references

  4. Laser-synchrotron studies of the dynamics of UV-photon-stimulated desorption in alkali halides

    International Nuclear Information System (INIS)

    Laser-synchrotron studies of neutral alkali emission from alkali halide crystals are yielding new insights into the dynamics of energy absorption, energy localization and bond-breaking in photon-stimulated desorption. The ground-state neutral desorption is triggered by thermal diffusion of photon-induced electronic defects; however, the excited-state neutral alkalis are formed in a surface-specific process on an extremely short time scale. In addition, there is new evidence for a surface overlayer which retards substrate desorption, thus suggesting a new approach to the optical damage problem at ultraviolet wavelengths

  5. Charge transfer dynamics from organometal halide perovskite to polymeric hole transport materials in hybrid solar cells

    OpenAIRE

    Brauer, Jan C.; Lee, Yong Hui; Nazeeruddin, Mohammad Khaja; Banerji, Natalie

    2016-01-01

    Organometal halide perovskites have emerged as promising next-generation solar cell technologies presenting outstanding efficiencies. However, many questions concerning their working principles remain to be answered. Here, we present a detailed study of hole transfer dynamics into polymeric hole transporting materials (HTMs), poly(triarylamine) (PTAA), poly(3-hexylthiophee-2,5-diyl (P3HT), and poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiaz...

  6. All-Inorganic Colloidal Quantum Dot Photovoltaics Employing Solution-Phase Halide Passivation

    KAUST Repository

    Ning, Zhijun

    2012-09-12

    A new solution-phase halide passivation strategy to improve the electronic properties of colloidal quantum dot films is reported. We prove experimentally that the approach leads to an order-of-magnitude increase in mobility and a notable reduction in trap state density. We build solar cells having the highest efficiency (6.6%) reported using all-inorganic colloidal quantum dots. The improved photocurrent results from increased efficiency of collection of infrared-generated photocarriers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Structural, optical, and electronic studies of wide-bandgap lead halide perovskites

    KAUST Repository

    Comin, Riccardo

    2015-01-01

    © The Royal Society of Chemistry 2015. We investigate the family of mixed Br/Cl organolead halide perovskites which enable light emission in the blue-violet region of the visible spectrum. We report the structural, optical and electronic properties of this air-stable family of perovskites, demonstrating full bandgap tunability in the 400-550 nm range and enhanced exciton strength upon Cl substitution. We complement this study by tracking the evolution of the band levels across the gap, thereby providing a foundational framework for future optoelectronic applications of these materials.

  8. Structural and chemical analysis of gadolinium halides encapsulated within WS2 nanotubes

    Science.gov (United States)

    Anumol, E. A.; Enyashin, Andrey N.; Batra, Nitin M.; Costa, Pedro M. F. J.; Deepak, Francis Leonard

    2016-06-01

    The hollow cavities of nanotubes serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of WS2 nanotubes by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is non-trivial due to the presence of multiple high atomic number elements. Therefore, energy dispersive X-ray spectroscopy (EDS) tomography was employed revealing the three dimensional chemical composition. Molecular dynamics simulations of the filling procedure shed light into the mechanics behind the formation of the confined gadolinium halide crystals. The quasi-1D system employed here serves as an example of a TEM-based chemical nanotomography method that could be extended to other materials, including beam-sensitive soft materials.The hollow cavities of nanotubes serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of WS2 nanotubes by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is non-trivial due to the

  9. Nickel-catalyzed Electrochemical Coupling of Phenyl Halide and Study of Mechanism

    Institute of Scientific and Technical Information of China (English)

    ZHAO, Peng; LUO, Yi-Wen; XUE, Teng; ZHANG, Ai-Jian; LU, Jia-Xing

    2006-01-01

    Electrochemical coupling of phenyl halide catalyzed by NiCl2bpy in DMF has been investigated in this paper.Stainless steel was used as cathode and zinc as anode. Effects of potential, temperature and catalyst on electrolyses were studied to optimize the electrolytic conditions, with the maximal isolated yield under potentiostatic electrolysis to be 85%. Cyclic voltammetry of NiCl2bpy in the presence of phenyl bromide has been studied and mechanisms,concerned with several kinds of nickel complex, have been summarized.

  10. Novel estimated surface tension data of actinide halide salts in the molten state

    International Nuclear Information System (INIS)

    The surface tension of ThF4, UF4 and UF6 is theoretically estimated, as function of temperature, whereas eight other halide salts only for temperature equal to their melting points. Calculations are based on a model, using statistical thermodynamics of Eyring theory. It is observed that the surface tension decreases linearly with temperature. The results are strictly compared with the available experimental data. The technique can be applied for conditions where experimental data are currently missing. The compressibility and surface tension products, of all salts under study, were also calculated

  11. Palladium-catalyzed cross-coupling reactions of aryl boronic acids with aryl halides in water.

    Science.gov (United States)

    Wang, Shaoyan; Zhang, Zhiqiang; Hu, Zhizhi; Wang, Yue; Lei, Peng; Chi, Haijun

    2009-01-01

    An efficient Suzuki cross-coupling reaction using a variety of aryl halides in neat water was developed. The Pd-catalyzed reaction between aryl bromides or chlorides and phenyl boronic acids was compatible with various functional groups and affords biphenyls in good to excellent yields without requirement of organic cosolvents. The air stability and solubility in water of the palladium-phosphinous acid complexes were considered to facilitate operation of the coupling reaction and product isolation. The reaction conditions including Pd catalyst selection, temperature, base and catalyst recoverability were also investigated. PMID:25084408

  12. Molecular interaction studies of glycylglycine in aqueous sodium halide solutions at 303, 308 and 313k

    Directory of Open Access Journals (Sweden)

    R. Palani

    2010-12-01

    Full Text Available Ultrasonic velocity, density and viscosity have been measured for glycylglycine in aqueous sodium halide (NaF, NaCl, NaBr mixture (0.5m at 303, 308 and 313K. Using the experimental values, the adiabatic compressibility, hydration number, apparent molal compressibility, apparent molal volume, limiting apparent molal compressibility, limiting apparent molal volume and their constants (SK, SV, transfer volumes at infinite dilution and viscosity B-coefficient of Jones-Dole equation were calculated. These parameters have been interpreted the molecular interactions in terms of solute-co-solute and solute-solvent interaction present in the given solutions.

  13. First-principles study on the electronic and optical properties of cubic ABX3 halide perovskites

    International Nuclear Information System (INIS)

    The electronic properties of ABX3 type compounds in the cubic phase are systematically studied using the first-principles calculations. The chemical trend of their properties as A or B or X varies is fully investigated. The optical properties of the ABX3 compounds are also investigated. Our calculations show that taking into account the spin–orbit coupling effect is crucial for predicting the accurate band gap of these halide perovskites. We predict that CH3NH3SnBr3 is a promising material for solar cells absorber with a perfect band gap and good optical absorption.

  14. Novel estimated surface tension data of actinide halide salts in the molten state

    Energy Technology Data Exchange (ETDEWEB)

    Aqra, Fathi, E-mail: fathiaqra2009@hotmail.com

    2014-05-01

    The surface tension of ThF{sub 4}, UF{sub 4} and UF{sub 6} is theoretically estimated, as function of temperature, whereas eight other halide salts only for temperature equal to their melting points. Calculations are based on a model, using statistical thermodynamics of Eyring theory. It is observed that the surface tension decreases linearly with temperature. The results are strictly compared with the available experimental data. The technique can be applied for conditions where experimental data are currently missing. The compressibility and surface tension products, of all salts under study, were also calculated.

  15. Enantioselective cross-coupling of meso-epoxides with aryl halides.

    Science.gov (United States)

    Zhao, Yang; Weix, Daniel J

    2015-03-11

    The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78-95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal, trifluoromethyl, sulfonamide, sulfonate ester), both aryl and vinyl halides, and five- to seven-membered rings. The intermediacy of a carbon radical is strongly suggested by the conversion of cyclooctene monoxide to an aryl [3.3.0]bicyclooctanol. PMID:25716775

  16. Tumoral calcium pyrophosphate deposition disease

    International Nuclear Information System (INIS)

    A report of two patients in which a soft tissue mass, initially regarded as a malignant tumor, was shown to be the result of calcium pyrophosphate deposition disease. The first case, a woman aged 71 years, presented with a mass involving the right fifth finger. In the second case, also a women aged 71 years, the lesion involved the tissues adjacent to the right hip. Each lesion consisted of a mass of highly cellular tissue containing deposits of calcium pyrophosphate dihydrate crystals. The clinical, radiological, and pathological features of the two cases are compared with those of seven similar cases reported in the literature. (orig.)

  17. Suzuki-Miyaura Cross-Coupling Reactions of Unactivated Alkyl Halides Catalyzed by a Nickel Pincer Complex

    OpenAIRE

    Di Franco, Thomas; Boutin, Nicolas; Hu, Xile

    2013-01-01

    A nickel(II) pincer complex, [((N2N)-N-Me)Ni-Cl], was used to catalyze alkyl-alkyl and alkyl-aryl Suzuki-Miyaura coupling reactions of unactivated alkyl halides. The coupling of 9-alkyl-9-borabicyclo[3.3.1]nonane and 9-phenyl-9-borabicyclo[3.3.1]nonane reagents with alkyl halides was achieved in modest to good yields. The reactions tolerated a variety of useful functional groups including ester, ether, furan, thioether, acetal, and Boc groups.

  18. Grand Canonical Monte Carlo coupled multiscale simulation for electrochemical and solvent parameters of silver halide systems in water.

    Science.gov (United States)

    Sudha, V; Harinipriya, S; Sangaranarayanan, M V

    2016-07-01

    Grand Canonical Monte Carlo methods in conjunction with continuum Multiscale simulation to estimate the hydration energies and surface potentials of silver halides as demonstrated elsewhere is employed by incorporating random distribution of molecules, nearest neighbor distances and hydration numbers. The extent of dehydration during each step and the corresponding variation in the hydration numbers are evaluated, assuming the validity of hard spheres. These estimates are then employed to deduce the redox potential of the reaction viz. 2AgX(solution)⇔2Ag(solid)+X2(gas). The dependence of these values on the nature of the halides and solvation characteristics is indicated. PMID:27442589

  19. Off-center impurity in alkali halides: reorientation, electric polarization and pairing to F center. III. Numerical calculations

    CERN Document Server

    Baldacchini, G; Grassano, U M; Scacco, A; Petrova, P; Mladenova, M; Ivanovich, M; Georgiev, M

    2007-01-01

    We carried out numerical calculations by an extended-Hueckel program in order to check the analytical results reported in the preceding Part I and Part II. We typically consider alkali halide clusters composed of some tens of constituent atoms to calculate electronic energies under static conditions or versus the displacements of particular atoms. Among other things, the off-center displacement of substitutional Li+ impurity in most alkali halides is evidenced. The trigonometric profile of the rotational barriers is also confirmed for KCl.

  20. The ejection anisotropy in the Coulomb explosion of some alkyl halide molecules under strong ps laser fields

    Science.gov (United States)

    Kaziannis, S.; Kosmidis, C.

    2009-01-01

    The ejection anisotropy of Coulomb explosion fragments released from alkyl halide molecules (C 2H 5X, 1-C 3H 7X and 1-C 4H 9X, where X = Br, Cl) under strong 35 ps laser irradiation is studied by means of time-of-flight mass spectrometry. By comparing the angular distributions widths of the halogen fragment ions originating from multiply charged molecular ions it is concluded that the ejection anisotropy presents a weak dependence on the mass of the halogen atom, observed especially in the case of ethyl halide molecules, while a stronger dependence is found on the size of the alkyl chain.

  1. Sequential One-Pot Ruthenium-Catalyzed Azide−Alkyne Cycloaddition from Primary Alkyl Halides and Sodium Azide

    KAUST Repository

    Johansson, Johan R.

    2011-04-01

    An experimentally simple sequential one-pot RuAAC reaction, affording 1,5-disubstituted 1H-1,2,3-triazoles in good to excellent yields starting from an alkyl halide, sodium azide, and an alkyne, is reported. The organic azide is formed in situ by treating the primary alkyl halide with sodium azide in DMA under microwave heating. Subsequent addition of [RuClCp*(PPh 3) 2] and the alkyne yielded the desired cycloaddition product after further microwave irradiation. © 2011 American Chemical Society.

  2. Possible configuration of two-knot auto-localized exciton in strainless and deformed alkali halide crystals

    International Nuclear Information System (INIS)

    In the paper molecular component of two-knot auto-localized exciton (TALE) occupying centrosymmetric state in alkali halide crystal cubic lattice with local D2h symmetry is considered. In is suggested that the symmetry lowering of forming small radius auto-localized exciton (ALE) is realizing in order configuration transformation by the scenario: multi-knot continual ALE (with Oh symmetry)→six-halide ALE (with Oh symmetry)→TALE (with Oh symmetry) or by the scenario Oh→D2h. Then for TALE with local D2h symmetry normal molecular ion shifts are considered as well

  3. Complex formation ions calcium with macromolecules pectin

    International Nuclear Information System (INIS)

    In clause the mechanism of sorption of ions of calcium by macromolecules of pectin is opened. Is shown, that the linkage of ions of calcium descends on acid bunches of pectin, and process carries cooperative character

  4. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Devkanya Dutta

    2000-12-01

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the store-operated calcium entry or capacitative calcium entry. Capacitative calcium current plays a key role in replenishing calcium stores and activating various physiological processes. Despite considerable efforts, very little is known about the molecular nature of the capacitative channel and the signalling pathway that activates it. This review summarizes our current knowledge about store operated calcium entry and suggests possible hypotheses for its mode of activation.

  5. Dairy Dilemma: Are You Getting Enough Calcium?

    Science.gov (United States)

    ... Dairy Dilemma Dairy Dilemma Are You Getting Enough Calcium? You may be avoiding dairy products because of ... But dairy products are a major source of calcium, vitamin D and other nutrients that are important ...

  6. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... can break easily, even without an obvious injury. Vitamin D helps your body absorb calcium. Eat foods that provide the right amounts of calcium, vitamin D, and protein. This kind of diet will give ...

  7. Physico-Chemical Study of the Separation of Calcium Isotopes by Chemical Exchange Between Amalgam and Salt Solutions

    International Nuclear Information System (INIS)

    In a preliminary study of the isotopic exchange between Ca amalgam and aqueous or organic solutions of Ca salts, the main parameters governing the feasibility of a separation process based on these systems such as separation factor, exchange kinetics, rate of decomposition of the amalgam were investigated. The separation factor between 40Ca and 46Ca was found to be of the order of 1.02. The rate of the exchange reaction is rather low for aqueous solutions, extremely low for organic solutions. The amalgam seems not to be attacked by dimethyl-formamide solutions; but it is rapidly decomposed by aqueous solutions of Ca halides. This decomposition is slow in the case of aqueous solutions of calcium formate and still slower for Ca(OH)2; however, except in particular conditions, the observed rate is often much higher, owing to interfering reactions between amalgam and water vapor contained in H2 bubbles. (authors)

  8. Calcium channel blockers and Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    Yi Tan; Yulin Deng; Hong Qing

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofi-brillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers in-volved in Alzheimer's disease therapy.

  9. Calcium channel blockers and Alzheimer's disease★

    OpenAIRE

    Tan, Yi; Deng, Yulin; Qing, Hong

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofibrillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers involved in...

  10. Teaching Calcium-Induced Calcium Release in Cardiomyocytes Using a Classic Paper by Fabiato

    Science.gov (United States)

    Liang, Willmann

    2008-01-01

    This teaching paper utilizes the materials presented by Dr. Fabiato in his review article entitled "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum." In the review, supporting evidence of calcium-induced calcium release (CICR) is presented. Data concerning potential objections to the CICR theory are discussed as well. In…

  11. Electrophysical properties of calcium orthovanadate

    International Nuclear Information System (INIS)

    The electron conductivity, dielectric permeability and magnetic susceptibility of calcium orthovanadate are studied. It is shown that structural transformations bring about changes in the nature of electrophysical properties of Ca3(VO4)2 and cause the charge redistribution in VO43- anion groups

  12. 21 CFR 582.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.1217 Section 582.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  13. 21 CFR 182.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium phosphate. 182.1217 Section 182.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  14. 21 CFR 582.5217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.5217 Section 582.5217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic)....

  15. 21 CFR 582.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  16. 21 CFR 582.5191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.5191 Section 582.5191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  17. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine,...

  18. 21 CFR 582.1205 - Calcium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium hydroxide. 582.1205 Section 582.1205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1205 Calcium hydroxide. (a) Product. Calcium hydroxide. (b) Conditions of use....

  19. 21 CFR 182.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2227 Calcium silicate. (a) Product. Calcium silicate....

  20. 21 CFR 582.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  1. Calcium dynamics in vascular smooth muscle

    OpenAIRE

    Amberg, Gregory C.; Navedo, Manuel F.

    2013-01-01

    Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells....

  2. Lactulose stimulates calcium absorption in postmenopausal women

    NARCIS (Netherlands)

    Heuvel, E.G.H.M. van den; Muijs, T.; Dokkum, W. van; Schaafsma, G.

    1999-01-01

    Animal studies have indicated that calcium absorption is increased by lactulose, a synthetic disaccharide. Therefore, the influence of lactulose on calcium absorption was measured in postmenopausal women who may benefit from the possible enhancing effect of lactulose on calcium absorption. Twelve po

  3. X-ray absorption of the Hg distribution in metal-halide lamps

    Energy Technology Data Exchange (ETDEWEB)

    Nimalasuriya, T; Zhu, X; Ridderhof, E J; Haverlag, M; Denisova, N; Stoffels, W W; Mullen, J J A M van der [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2008-01-21

    Spatial temperature profiles of metal-halide lamps have been acquired using x-ray absorption of the Hg density distribution. The temperature profiles were determined by combining the measured absorption of the spatially resolved Hg density with the wall temperature. The data analysis of x-ray absorption is extensive. After the necessary image reconstruction, the line integrated density profile needs to be Abel inverted. The solution from the Abel inversion is stabilized with the Tikhonov regularization parameter. The previous method for x-ray absorption developed in our group has been modified and improved by utilizing the following: (1) a larger outer bulb, (2) the corrections for x-ray scattering on the lamp materials, (3) an optimum value of Tikhonov regularization parameter {mu}, and (4) employing a higher degree of polynomials used for the Abel inversion. For a similar lamp as reported previously by Zhu, we found an axis temperature of 6200 K instead of 5200 K. The higher temperature is similar to what is found using optical spectroscopic methods. Typical results from a metal-halide lamp with and without salts are shown.

  4. X-ray absorption of the Hg distribution in metal-halide lamps

    International Nuclear Information System (INIS)

    Spatial temperature profiles of metal-halide lamps have been acquired using x-ray absorption of the Hg density distribution. The temperature profiles were determined by combining the measured absorption of the spatially resolved Hg density with the wall temperature. The data analysis of x-ray absorption is extensive. After the necessary image reconstruction, the line integrated density profile needs to be Abel inverted. The solution from the Abel inversion is stabilized with the Tikhonov regularization parameter. The previous method for x-ray absorption developed in our group has been modified and improved by utilizing the following: (1) a larger outer bulb, (2) the corrections for x-ray scattering on the lamp materials, (3) an optimum value of Tikhonov regularization parameter μ, and (4) employing a higher degree of polynomials used for the Abel inversion. For a similar lamp as reported previously by Zhu, we found an axis temperature of 6200 K instead of 5200 K. The higher temperature is similar to what is found using optical spectroscopic methods. Typical results from a metal-halide lamp with and without salts are shown

  5. Comparative study of energy-efficiency and conservation systems for ceramic metal-halide discharge lamps

    International Nuclear Information System (INIS)

    Interest in energy savings in urban lighting is gaining traction and has become a priority for municipal administrations. LED (light-emitting diode) technology appears to be the clear future lighting choice. However, this technology is still rapidly developing and has not been sufficiently tested. As an intermediate step, alternative proposals for energy-saving equipment for traditional discharge lamps are desirable so that the current technologies can coexist with the new LED counterparts for the short and medium term. This article provides a comparative study between two efficiency and energy-saving systems for discharge lamps with metal-halide and ceramic technologies, i.e., a lighting flow dimmer-stabilizer and a double-level electronic ballast. - Highlights: ► It has been demonstrated the possibility of regulating ceramic metal-halide lamps with lighting flow dimmer-stabilizer. ► Electronic ballasts can save approximately double quantity of energy than lighting flow dimmer-stabilizers. ► The use of lighting flow dimmer-stabilizer is more profitable than electronic ballasts due to costs and reliability

  6. Correlation between deformation bleaching and mechanoluminescence in coloured alkali halide crystals

    Indian Academy of Sciences (India)

    B P Chandra; M Ramrakhiani; P Sahu; A M Rastogi

    2000-02-01

    The present paper reports the correlation between deformation bleaching of coloration and mechanoluminescence (ML) in coloured alkali halide crystals. When the -centre electrons captured by moving dislocations are picked up by holes, deep traps and other compatible traps, then deformation bleaching occurs. At the same time, radiative recombination of dislocation captured electrons with the holes gives rise to the mechanoluminescence. Expressions are derived for the strain dependence of the density of colour centres in deformed crystals and also for the number of colour centres bleached. So far as strain, temperature, density of colour centres, a and volume dependence are concerned, there exists a correlation between the deformation bleaching and ML in coloured alkali halide crystals. From the strain dependence of the density of colour centres in deformed crystals, the value of coefficient of deformation bleaching is determined and it is found to be 1.93 and 2.00 for KCl and KBr crystals, respectively. The value of $(D + \\mathcal{X})$ is determined from the strain dependence of the ML intensity and it is found to be 2.6 and 3.7 for KCl and KBr crystals, respectively. This gives the value of coefficient of deformation generated compatible traps $\\mathcal{X}$ to be 0.67 and 1.7 for KCl and KBr crystals, respectively.

  7. Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

    Directory of Open Access Journals (Sweden)

    A. Jammoul

    2009-07-01

    Full Text Available The interactions between triplet state benzophenone and halide anion species (Cl, Br and I have been studied by laser flash photolysis (at 355 nm in aqueous solutions at room temperature. The decay of the triplet state of benzophenone was followed at 525 nm. Triplet lifetime measurements gave rate constants, kq (M−1 s, close to diffusion controlled limit for iodide (~8×109 M−1 s, somewhat less for bromide (~3×108 M−1 s and much lower for chloride (<106 M−1 s. The halide (X quenches the triplet state; the resulting product has a transient absorption at 355 nm and a lifetime much longer than that of the benzophenone triplet state, is formed. This transient absorption feature matches those of the corresponding radical anion (X2. We therefore suggest that such reactive quenching is a photosensitized source of halogen in the atmosphere or the driving force for the chemical oxidation of the oceanic surface micro layer.

  8. Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

    Directory of Open Access Journals (Sweden)

    Xiaoqian Ai

    2016-05-01

    Full Text Available The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18 intercalated in graphite oxide (GO have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16 or bilayers (when n = 18, with their long axis parallel to GO layers, and with cations of headgroups bonded ionically to C-O- groups of GO; backbones of the confined molecules remain free. All halides and intercalation compounds suffer dielectric loss at low temperature. Arrhenius plots of the thermal dependence of the loss peaks, which are asymmetric, produce apparent activation energies that rise with increasing n. Ngai’s correlated-state model helps to correct for effects of dipole-dipole interaction, leading to virtually identical values for actual activation energy of 110 meV ± 5%; the values are also almost the same as the barrier energy for internal rotation in the alkyl macromolecule. We conclude that the relaxation of the alkylammonium cations arises not from C3 reorientation of the CH3 at its headgroup, but from small-angle wobbling around its major axis, an intrinsic motion.

  9. Rhodium-catalysed asymmetric allylic arylation of racemic halides with arylboronic acids

    Science.gov (United States)

    Sidera, Mireia; Fletcher, Stephen P.

    2015-11-01

    Csp2-Csp2 cross-coupling reactions between arylboronic acid and aryl halides are widely used in both academia and industry and are strategically important in the development of new agrochemicals and pharmaceuticals. Csp2-Csp3 cross-coupling reactions have been developed, but enantioselective variations are rare and simply retaining the stereochemistry is a problem. Here we report a highly enantioselective Csp2-Csp3 bond-forming method that couples arylboronic acids to racemic allyl chlorides. Both enantiomers of a cyclic chloride are converted into a single enantiomer of product via a dynamic kinetic asymmetric transformation. This Rh-catalysed method uses readily available and inexpensive building blocks and is mild and broadly applicable. For electron-deficient, electron-rich or ortho-substituted boronic acids better results are obtained with racemic allyl bromides. Oxygen substitution in the allyl halide is tolerated and the products can be functionalized to provide diverse building blocks. The approach fills a significant gap in the methods for catalytic asymmetric synthesis.

  10. Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates.

    Science.gov (United States)

    Liang, Dong; Peng, Yuelin; Fu, Yongping; Shearer, Melinda J; Zhang, Jingjing; Zhai, Jianyuan; Zhang, Yi; Hamers, Robert J; Andrew, Trisha L; Jin, Song

    2016-07-26

    Violet electroluminescence is rare in both inorganic and organic light-emitting diodes (LEDs). Low-cost and room-temperature solution-processed lead halide perovskites with high-efficiency and color-tunable photoluminescence are promising for LEDs. Here, we report room-temperature color-pure violet LEDs based on a two-dimensional lead halide perovskite material, namely, 2-phenylethylammonium (C6H5CH2CH2NH3(+), PEA) lead bromide [(PEA)2PbBr4]. The natural quantum confinement of two-dimensional layered perovskite (PEA)2PbBr4 allows for photoluminescence of shorter wavelength (410 nm) than its three-dimensional counterpart. By converting as-deposited polycrystalline thin films to micrometer-sized (PEA)2PbBr4 nanoplates using solvent vapor annealing, we successfully integrated this layered perovskite material into LEDs and achieved efficient room-temperature violet electroluminescence at 410 nm with a narrow bandwidth. This conversion to nanoplates significantly enhanced the crystallinity and photophysical properties of the (PEA)2PbBr4 samples and the external quantum efficiency of the violet LED. The solvent vapor annealing method reported herein can be generally applied to other perovskite materials to increase their grain size and, ultimately, improve the performance of optoelectronic devices based on perovskite materials. PMID:27336850

  11. Metallotropic liquid crystals formed by surfactant templating of molten metal halides.

    Science.gov (United States)

    Martin, James D; Keary, Cristin L; Thornton, Todd A; Novotnak, Mark P; Knutson, Jeremey W; Folmer, Jacob C W

    2006-04-01

    Liquid crystals consist of anisotropic molecular units, and most are organic molecules. Materials incorporating metals into anisotropic molecules, described as metallomesogens, have been prepared. Anisotropic structures such as one-dimensional chains and two-dimensional layers are frequently observed in solid-state inorganic materials, however, little is understood about structural organization in melts of such materials. Achieving liquid-crystalline behaviour in inorganic fluids should be possible if the anisotropic structure can be retained or designed into the molten phase. We demonstrated the ability to engineer zeolite-type structures into metal halide glasses and liquids. In this work we have engineered lamellar, cubic and hexagonal liquid-crystalline structure in metal-halide melts by controlling the volume fraction and nature of the inorganic block (up to 80 mol%) with respect to alkylammonium surfactants. The high metal content of these liquid-crystalline systems significantly advances the field of metallomesogens, which seeks to combine magnetic, electronic, optical, redox and catalytic properties common to inorganic materials with the fluid properties of liquid crystals. PMID:16547520

  12. Structural and Chemical Analysis of Gadolinium Halides Encapsulated within WS 2 Nanotubes

    KAUST Repository

    Anumol, E A

    2016-05-18

    The hollow cavities of nanotubes could serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of inorganic nanotubes of WS2 by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is a non-trivial matter due to the presence of multiple high atomic number elements. Therefore, energy dispersive X-ray spectroscopy (EDS) tomography was employed revealing the three dimensional chemical composition. Molecular dynamics simulations of the filling procedure shed light into the mechanics behind the formation of the confined gadolinium halide crystals. The quasi-1D system employed here serves as an example of a TEM-based chemical nanotomography method that could be extended to other materials, including beam-sensitive soft materials.

  13. Effects of Halide Ions on the Carbamidocyclophane Biosynthesis in Nostoc sp. CAVN2

    Directory of Open Access Journals (Sweden)

    Michael Preisitsch

    2016-01-01

    Full Text Available In this study, the influence of halide ions on [7.7]paracyclophane biosynthesis in the cyanobacterium Nostoc sp. CAVN2 was investigated. In contrast to KI and KF, supplementation of the culture medium with KCl or KBr resulted not only in an increase of growth but also in an up-regulation of carbamidocyclophane production. LC-MS analysis indicated the presence of chlorinated, brominated, but also non-halogenated derivatives. In addition to 22 known cylindrocyclophanes and carbamidocyclophanes, 27 putative congeners have been detected. Nine compounds, carbamidocyclophanes M−U, were isolated, and their structural elucidation by 1D and 2D NMR experiments in combination with HRMS and ECD analysis revealed that they are brominated analogues of chlorinated carbamidocyclophanes. Quantification of the carbamidocyclophanes showed that chloride is the preferably utilized halide, but incorporation is reduced in the presence of bromide. Evaluation of the antibacterial activity of 30 [7.7]paracyclophanes and related derivatives against selected pathogenic Gram-positive and Gram-negative bacteria exhibited remarkable effects especially against methicillin- and vancomycin-resistant staphylococci and Mycobacterium tuberculosis. For deeper insights into the mechanisms of biosynthesis, the carbamidocyclophane biosynthetic gene cluster in Nostoc sp. CAVN2 was studied. The gene putatively coding for the carbamoyltransferase has been identified. Based on bioinformatic analyses, a possible biosynthetic assembly is discussed.

  14. Evaluation of quaternary ammonium halides for removal of methyl iodide from flowing air streams

    International Nuclear Information System (INIS)

    The quaternary ammonium halides of several tertiary amines were used as impregnants on activated carbon and were tested for methyl iodide penetration in accordance with test Method A, ASTM D3803, 1979, ''Standard Test Methods for Radio-iodine Testing of Nuclear Grade Gas Phase Adsorbents''. The results suggest that the primary removal mechanism for methyl iodide-131 is isotopic exchange with the quaternary ammonium halide. For example, a 5 wt% impregnation of each of the tetramethyl, tetraethyl, tetrapropyl and tetrabutyl ammonium iodides on activated carbon yielded percent penetrations of 0.47, 0.53, 0.78, and 0.08 respectively when tested according to Method A of ASTM D3803. A sample impregnated with 5% tetramethyl ammonium hydroxide gave a methyl iodide penetration of 64.87%, thus supporting the isotopic exchange mechanism for removal. It has been a generally held belief that the success of tertiary amines as impregnants for radioiodine removal is a result of their ability to complex with the methyl iodide. The results of the work indicates that the superiority of the tertiary amines similar to triethylene diamine and quinuclidine, when compared to their straight chain analogs, is a result of their ease in reacting with methyl iodide-127 to form the quaternary ammonium iodide followed by isotopic exchange

  15. Photo-induced halide redistribution in organic-inorganic perovskite films.

    Science.gov (United States)

    deQuilettes, Dane W; Zhang, Wei; Burlakov, Victor M; Graham, Daniel J; Leijtens, Tomas; Osherov, Anna; Bulović, Vladimir; Snaith, Henry J; Ginger, David S; Stranks, Samuel D

    2016-01-01

    Organic-inorganic perovskites such as CH3NH3PbI3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3 films under illumination. We demonstrate that the photo-induced 'brightening' of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance. PMID:27216703

  16. Inorganic hole conductor-based lead halide perovskite solar cells with 12.4% conversion efficiency

    KAUST Repository

    Qin, Peng

    2014-05-12

    Organo-lead halide perovskites have attracted much attention for solar cell applications due to their unique optical and electrical properties. With either low-temperature solution processing or vacuum evaporation, the overall conversion efficiencies of perovskite solar cells with organic hole-transporting material were quickly improved to over 15% during the last 2 years. However, the organic hole-transporting materials used are normally quite expensive due to complicated synthetic procedure or high-purity requirement. Here, we demonstrate the application of an effective and cheap inorganic p-type hole-transporting material, copper thiocyanate, on lead halide perovskite-based devices. With low-temperature solution-process deposition method, a power conversion efficiency of 12.4% was achieved under full sun illumination. This work represents a well-defined cell configuration with optimized perovskite morphology by two times of lead iodide deposition, and opens the door for integration of a class of abundant and inexpensive material for photovoltaic application. © 2014 Macmillan Publishers Limited.

  17. Photo-induced halide redistribution in organic-inorganic perovskite films

    Science.gov (United States)

    Dequilettes, Dane W.; Zhang, Wei; Burlakov, Victor M.; Graham, Daniel J.; Leijtens, Tomas; Osherov, Anna; Bulović, Vladimir; Snaith, Henry J.; Ginger, David S.; Stranks, Samuel D.

    2016-05-01

    Organic-inorganic perovskites such as CH3NH3PbI3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3 films under illumination. We demonstrate that the photo-induced `brightening' of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance.

  18. Photo-induced halide redistribution in organic–inorganic perovskite films

    Science.gov (United States)

    deQuilettes, Dane W.; Zhang, Wei; Burlakov, Victor M.; Graham, Daniel J.; Leijtens, Tomas; Osherov, Anna; Bulović, Vladimir; Snaith, Henry J.; Ginger, David S.; Stranks, Samuel D.

    2016-01-01

    Organic–inorganic perovskites such as CH3NH3PbI3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3 films under illumination. We demonstrate that the photo-induced ‘brightening' of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance. PMID:27216703

  19. Enthalpic Interaction for α-Amino Acid with Alkali Metal Halides in Water

    Institute of Scientific and Technical Information of China (English)

    LU,Yan(卢雁)

    2004-01-01

    The studies of the enthalpic interaction parameters, hxy, hxyy and hxxv, of alkali metal halides with glycine,α-alanine and α-aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the α-amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt's effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxy with the radius of cations is not evident. The value of hxyy will increase with the increase of the radii of the ions. As the increase of the number of carbon atoms of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α-alanine for the ions which have small size. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.

  20. Linear chrono-amperometry using re-dissolution: application to halides

    International Nuclear Information System (INIS)

    The possibility of applying linear chrono-amperometry to analysis was studied using a falling-drop mercury electrode. Measurements of the cations were carried out by direct reduction or by prior formation of an amalgam, which is then oxidized. Using the first technique, the minimum concentration that can be attained is about 10-6 M and the reproducibility of the results is of the order of 2%. With the second method the sensitivity is much improved: in the concentration range of 10-7 to 10-8 M, the scatter of the results is less than 10% if the agitation and temperature conditions are kept constant. The halides are determined by re-dissolving the mercurous halide deposit formed by electrolysis. From the analytical point of view, the sensitivity is limited in the domain where the phenomena can be interpreted and used. In the case of the chloride ion the lower limit of this zone is close to 10-5 M; it is 10-6 M for the bromide and less than 10-7 M for the iodide. For lower concentrations, simple laws that might be applied in analysis are no longer valid. However, the splitting of the peak observed during the reduction of the mercurous iodide deposit was interpreted as showing that the mono-molecular Hg2I2 layer formed on the drop has particular electrochemical properties. (authors)

  1. Assignment of photoelectron spectra of halide-water clusters: Contrasting patterns of delocalization in Dyson orbitals

    Science.gov (United States)

    Dolgounitcheva, O.; Zakrzewski, V. G.; Ortiz, J. V.

    2013-04-01

    Ab initio electron propagator calculations in various self-energy approximations provide accurate assignments of peaks observed in the photoelectron spectra of complexes that comprise a fluoride or chloride anion and two or three water molecules. More than one minimum structure is found in all four cases. When the halide anion is Cl-, the first three final states may be described as quasi-degenerate 2P chlorine atoms coordinated to water molecules. Higher final states consist of a chloride anion juxtaposed to a positive charge that is delocalized over the water molecules. For the clusters with fluoride anions, most of the final states correspond to Dyson orbitals that are delocalized over the F and O nuclei. A variety of F-O σ and π bonding and antibonding patterns are evident in the Dyson orbitals. The assignment of low-lying spectral peaks to halide p orbital vacancies or to delocalized solvent orbitals is more valid for the chloride clusters than for the fluoride clusters, where a delocalized picture arises from strong bonding interactions between F 2p and H2O 1b1 orbitals.

  2. Sodium/Calcium Exchangers Selectively Regulate Calcium Signaling in Mouse Taste Receptor Cells

    OpenAIRE

    Szebenyi, Steven A.; Laskowski, Agnieszka I.; Medler, Kathryn F.

    2010-01-01

    Taste cells use multiple signaling mechanisms to generate appropriate cellular responses to discrete taste stimuli. Some taste stimuli activate G protein coupled receptors (GPCRs) that cause calcium release from intracellular stores while other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). While the signaling mechanisms that initiate calcium signals have been described in taste cells, the calcium clearance mechanisms (CCMs) that contrib...

  3. Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille;

    2013-01-01

    BACKGROUND: Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation...... offers several advantages over standard treatment options: calcium is inexpensive and may readily be applied without special precautions, as is the case with cytostatic drugs. Therefore, details on the use of calcium electroporation are essential for carrying out clinical trials comparing calcium...... electroporation and electrochemotherapy. METHODS: The effects of calcium electroporation and bleomycin electroporation (alone or in combination) were compared in three different cell lines (DC-3F, transformed Chinese hamster lung fibroblast; K-562, human leukemia; and murine Lewis Lung Carcinoma). Furthermore...

  4. Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

    OpenAIRE

    Zenei Taira, Zenei

    2013-01-01

    Yukari Ueda, Zenei TairaFaculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, JapanAbstract: We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 ...

  5. Calcium signals and calcium channels in osteoblastic cells

    Science.gov (United States)

    Duncan, R. L.; Akanbi, K. A.; Farach-Carson, M. C.

    1998-01-01

    Calcium (Ca2+) channels are present in non-excitable as well as in excitable cells. In bone cells of the osteoblast lineage, Ca2+ channels play fundamental roles in cellular responses to external stimuli including both mechanical forces and hormonal signals. They are also proposed to modulate paracrine signaling between bone-forming osteoblasts and bone-resorbing osteoclasts at local sites of bone remodeling. Calcium signals are characterized by transient increases in intracellular Ca2+ levels that are associated with activation of intracellular signaling pathways that control cell behavior and phenotype, including patterns of gene expression. Development of Ca2+ signals is a tightly regulated cellular process that involves the concerted actions of plasma membrane and intracellular Ca2+ channels, along with Ca2+ pumps and exchangers. This review summarizes the current state of knowledge concerning the structure, function, and role of Ca2+ channels and Ca2+ signals in bone cells, focusing on the osteoblast.

  6. Computational study of a calcium release-activated calcium channel

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-05-01

    The naturally occurring proteins that form hole in membrane are commonly known as ion channels. They play multiple roles in many important biological processes. Deletion or alteration of these channels often leads to serious problems in the physiological processes as it controls the flow of ions through it. The proper maintenance of the flow of ions, in turn, is required for normal health. Here we have investigated the behavior of a calcium release-activated calcium ion channel with pdb entry 4HKR in Drosophila Melanogaster. The equilibrium energy as well as molecular dynamics simulation is performed first. The protein is subjected to molecular dynamics simulation to find their energy minimized value. Simulation of the protein in the environment of water and ions has given us important results too. The solvation energy is also found using Charmm potential.

  7. Using Group-Inquiry to Study Differing Reaction Conditions in the E2 Elimination of Cyclohexyl Halides

    Science.gov (United States)

    Long, Robert D.

    2012-01-01

    In this experiment, students individually conduct one of several variations of an E2 dehydrohalogenation reaction on a cyclohexyl halide substrate for 30 min, which is sufficient only for a partial reaction to occur. The variations examine reaction conditions including different leaving groups, decreased reaction temperature, or reduced base…

  8. CuI-Catalyzed: One-Pot Synthesis of Diaryl Disulfides from Aryl Halides and Carbon Disulfide

    OpenAIRE

    Mohammad Soleiman-Beigi; Azadeh Izadi

    2013-01-01

    A new application of carbon disulfide in the presence of KF/Al2O3 is reported for the synthesis of organic symmetrical diaryl disulfides. These products were synthesized by one-pot reaction of aryl halides with the in situ generated trithiocarbonate ion in the presence of copper under air atmosphere.

  9. Green Synthesis and Regioselective Control of Sn/I2 Mediated Allylation of Carbonyl Compounds with Crotyl Halide in Water

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Yan; ZHA,Zhang-Gen; ZHOU,Yu-Qing; WANG,Zhi-Yong

    2004-01-01

    @@ Barbier-type carbonyl allylation is particularly useful due to ease of operation and the availability and tractability of allylic substrates,[1] Metals such as indium, zinc and tin are often used as the mediator. Here we present a green approach toward the synthesis, that is, Sn/I2 mediated allylation of carbonyl compounds with crotyl halide in water.

  10. Study on Analysis of Halides in Semi-Product and Product Obtained from Production of UO2 Fuel by Pyrohydrolysis

    International Nuclear Information System (INIS)

    The pyrohydrolytic apparatus has been designed in details according to a structural scheme published in a reference and ordered for the manufacture in overseas company. The study on quantitative separation of halides (F, Cl, Br, I) in solid and liquid samples containing uranium by using pyrohydrolysis technique has then been carried out in Center for Analytical Chemistry, ITRRE. The recovery of pyrohydrolytic reaction of all studied halides at 1000 oC for about 30 minutes using their pure compounds reached nearly 99% on this complete system. The ion chromatography (IC) and the Inductively coupled plasma-mass spectrometry (ICP-MS) were investigated for the determination of halide anions in the condensed solutions. The fluoride and chloride content in UO2 powder and/or in solution containing uranium samples was determined by using IC meanwhile the concentration of bromide and iodide in these samples was quantified by using ICP-MS with internal standard technique. The relatively standard deviation of all measurement existed within 10% and hence, the analytical procedures can be applicable for the quantitative determination of these above mentioned halides in engineering researched samples. (author)

  11. Intra- and Intermolecular Nickel-Catalyzed Reductive Cross-Electrophile Coupling Reactions of Benzylic Esters with Aryl Halides.

    Science.gov (United States)

    Konev, Mikhail O; Hanna, Luke E; Jarvo, Elizabeth R

    2016-06-01

    Nickel-catalyzed cross-electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter- and intramolecular variants proceed under mild reaction conditions. A range of heterocycles and functional groups are tolerated under the reaction conditions. Additionally, the first example of a stereospecific cross-electrophile coupling of a secondary benzylic ester is described. PMID:27099968

  12. "Stripping" the carbon atom of methyl halide by a cationic holmium complex: a gas-phase study.

    Science.gov (United States)

    Zhou, Shaodong; Schlangen, Maria; Li, Jilai; Wu, Xiao-Nan; Schwarz, Helmut

    2015-10-01

    Mechanistic aspects of an unusual reaction of [HoC6 H4 S](+) with CH3 X (X=Cl, Br, I) have been investigated using Fourier-transform ion cyclotron resonance mass spectrometry combined with density functional theory (DFT) calculations. In this thermal process, all four bonds of the methyl halides are cleaved. PMID:26331900

  13. A copper-catalyzed coupling reaction of vinyl halides and carbazates: application in the assembly of polysubstituted pyrroles.

    Science.gov (United States)

    Zhou, Chengang; Ma, Dawei

    2014-03-21

    CuI-catalyzed coupling of vinyl halides with carbazates gives N-protected N-alkenylhydrazines, which are condensed with ketones under acidic conditions to give polysubstituted pyrroles. The pyrrole synthesis may go through a similar mechanism with Fischer indole synthesis, which involves a [3,3]-sigmatropic rearrangement and other reactions. PMID:24514455

  14. Substitution of calcium by strontium within selected calcium phosphates

    Science.gov (United States)

    Rokita, E.; Hermes, C.; Nolting, H.-F.; Ryczek, J.

    1993-06-01

    Sr incorporation in the molecules of amorphous calcium phosphate, apatitic tricalcium phosphate, hydroxyapatite, octacalcium phosphate and dicalcium phosphate dihydrate was investigated. The concentration of Sr ranged from 225 to 1010 μ g / g, i.e. it overlapped with the physiological range of Sr concentrations in human bone. The leading experimental technique was extended X-ray absorption fine structure (EXAFS) at the Sr K edge. Results of these studies demonstrated the following: (1) Sr incorporation in the calcium phosphates is compound-dependent, (2) the coordination of incorporated Sr atoms in the Ca-P molecules is similar to that of Ca atoms, but interatomic distances are ≈0.015 nm larger, (3) in apatitic tricalcium phosphate, hydroxyapatite and octacalcium phosphate lattices Sr atoms may occupy selected Ca sites, which was not the case for dicalcium phosphate dihydrate, (4) in the apatite lattice Sr atoms are coordinated by 6 PO 4 tetrahedrals and (5) EXAFS spectra at the K edge of the incorporated Sr may be used to distinguish the structures of amorphous calcium phosphate, dicalcium phosphate dihydrate as well as apatite and its derivatives (apatitic tricalcium phosphate, octacalcium phosphate).

  15. USING CALCIUM CARBONATE WHISKERS AS PAPERMAKING FILLER

    Directory of Open Access Journals (Sweden)

    Xiaoyu Chen

    2011-05-01

    Full Text Available Whiskers, having large length/diameter ratio, are fiber-shaped single crystals. The technical possibility of using calcium carbonate whiskers as papermaking filler to replace conventional powder-like calcium carbonate was investigated. The results showed that it may be feasible to use calcium carbonate whisker as papermaking filler. Compared with conventional precipitated calcium carbonate, calcium carbonate whisker had higher retention efficiency. The use of calcium carbonate whisker also favorably affected the strength properties of paper sheets. A model was proposed to suggest the mechanism for paper strength improvement. The whiskers filled in paper sheets could increase the friction between fibers, thus increasing bonding strength. Moreover, the strength properties of paper were further improved because calcium carbonate whiskers were partly embedded in pulp fiber walls.

  16. CALCIUM ENHANCES ANTIINFLAMMATORY ACTIVITY OF ASPIRIN

    Directory of Open Access Journals (Sweden)

    Choksi Krishna

    2011-03-01

    Full Text Available The objective of present study is to evaluate the effects of calcium carbonate and calcium gluconate on acute and subacute inflammation and to study their possible interactions with Aspirin. Calcium carbonate (10 mg/kg and calcium gluconate (5 mg/kg were administered individually and also co-administered along with sub therapeutic dose Aspirin (50mg/kg to study their interaction. The inflammation was induced by carrageenan or a foreign body. Both calcium carbonate and calcium gluconate could not show significant anti-inflammatory activity on their own in acute as well as subacute inflammation models. Aspirin at sub-anti-inflammatory dose (50mg/Kg when co-administered along with calcium salts produced the significant anti-inflammatory response which was comparable to anti-inflammatory response of aspirin at therapeutic dose (200mg/Kg. Also co-adminostration minimized the gastro-toxicity of aspirin.

  17. An experimental study of formation of the mercury mixed halides HgClBr and HgBrI and of their purity

    OpenAIRE

    Rabia Ahmad; Jamshed Ali; Qamer Faisal

    2015-01-01

    Claims to have produced the mixed halides of mercury are very old. However, their stability or even their very existence was seriously questioned by Ammlung and Brill several decades back, on the basis of their study, in several solvents, of what was thought to be HgBrI. The mixed halide HgClI was already known to be unstable. On the basis of these facts, which were also lent some theoretical support, it was strongly conjectured that the mixed halides of mercury and similar elements, were...

  18. [Calcium pyrophosphate dihydrate deposition disease].

    Science.gov (United States)

    Koitschev, C; Kaiserling, E; Koitschev, A

    2003-08-01

    Calcium pyrophosphate dihydrate deposition disease (CPPD) of the temporomandibular joint is rare. The disorder is characterized by the presence of crystal deposits within the affected joint. The deposition of crystals in adjacent soft tissue may lead to the formation of pseudotumors. This form of the disease is called tophaceous pseudogout and typically affects the temporomandibular joint. It is difficult to differentiate the disease, particularly from malignant tumors, on the clinical and radiographic findings alone. The diagnosis is based on histological identification of the calcium pyrophosphate crystals. We present an unusually advanced case of tophaceous pseudogout of the temporomandibular joint. The etiology, clinical and diagnostic criteria as well as treatment options are discussed on the basis of our own experience and a review of the literature. PMID:12942180

  19. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins

    DEFF Research Database (Denmark)

    Hsu, Yu-Juei; Dimke, Henrik Anthony; Schoeber, Joost P H;

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had...... higher urinary calcium excretion than female mice and their renal calcium transporters were expressed at a lower level. We also found that orchidectomized mice excreted less calcium in their urine than sham-operated control mice and that the hypocalciuria was normalized after testosterone replacement...... calcium transport. Thus, our study shows that gender differences in renal calcium handling are, in part, mediated by the inhibitory actions of androgens on TRPV5-mediated active renal calcium transport....

  20. Influence of calcium oxalate crystal accumulation on the calcium content of seeds from Medicago truncatula.

    Science.gov (United States)

    Nakata, Paul A

    2012-04-01

    Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this potential role, microscopic and biochemical comparisons were conducted on the different tissues of Medicago truncatula wild-type and the calcium oxalate defective (cod) 5 which lacks the ability to accumulate prismatic crystals in the cells adjacent to the vascular bundles. Calcium measurements showed that cod5 seeds had more calcium and cod5 pods contained less calcium than the corresponding wild-type tissues. Roots, stems, and leaves from cod5 and wild-type had similar calcium content. Although cod5 was devoid of prismatic crystals, cod5 pods were observed to form druse crystals of calcium oxalate not found in wild-type pods. Taken together these findings suggest a functional role for calcium oxalate formation in regulating calcium transport to the seeds. Regulating calcium uptake at the roots also appeared to be another point of control in determining seed calcium content. Overall, regulating the long distance transport and partitioning of calcium to the seeds appears to be a complex process with multiple points of control. PMID:22325887