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Sample records for alkaline earth metal complexes

  1. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    Gamez, F.; Hurtado, P.; Martinez-Haya, B.; G. Berden,; Oomens, J.

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg(2+), Ca(2+). Sr(2+) and Ba(2+)) stored in the cell of a Fourier Transform Ion Cyclotron Resonan

  2. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    F. Gámez; P. Hurtado; B. Martínez-Haya; G. Berden; J. Oomens

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg2+, Ca2+, Sr2+ and Ba2+) stored in the cell of a Fourier Transform Ion Cyclotron Resonance mass

  3. Synthesis of complex plutonium oxides with alkaline-earth metals

    International Nuclear Information System (INIS)

    Complex plutonium(IV) oxides with strontium and barium, SuPuO3 and BaPuO3, were synthesized and their crystal structure was analyzed. Compacted mixture of plutonium dioxide powder and the carbonate of strontium or barium was heated in a stream of argon gas using a cell with a small orifice. The products obtained were found to be composed of a nearly single phase showing the structure of orthorhombic slightly distorted from cubic. (author)

  4. Effects of alkaline earth metal ion complexation on amino acid zwitterion stability: Results from infrared action spectroscopy

    NARCIS (Netherlands)

    Bush, M. F.; Oomens, J.; Saykally, R. J.; Williams, E. R.

    2008-01-01

    The structures of isolated alkaline earth metal cationized amino acids are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy and theory. These results indicate that arginine, glutamine, proline, serine, and valine all adopt zwitterionic structures when complexed with diva

  5. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere

    Indian Academy of Sciences (India)

    Jayeeta Bhattacharjee; Ravi K Kottalanka; Harinath Adimulam; Tarun K Panda

    2014-09-01

    We report the monomeric complexes of magnesium and calcium of composition [M(THF){2-Ph2P(Se)N(CMe3)}2] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)2{Ph2P(Se)N(CMe3)}] (2) and [K(THF)Ba{Ph2P(Se)N(CMe3)}3](5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg2+ (0.72Å) and Ca2+ (0.99Å) ions form the monomeric complex, whereas the larger ions K+ (1.38Å) and Ba2+ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

  6. Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol

    Science.gov (United States)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2012-11-01

    A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  7. Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal*

    OpenAIRE

    Song, Ming-Zhi; Zhu, Lan-ying; Gao, Xi-ke; Dou, Jian-Min; Sun, De-zhi

    2004-01-01

    Thermodynamic parameters of complexation of naphto-15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of sta...

  8. Mass spectra of alkaline earth salts with a FAB source. Complexation with crown ethers

    International Nuclear Information System (INIS)

    With a liquid desorption FAB source it is possible to obtain alkaline earth metal ions complexed by a crown ether. Conditions for formation of these complexes ions are examined for selection of the complexing agent in function of cation size. Behaviour of alkaline and alkaline earth compounds are compared allowing the differentiation of ion extraction phenomena by liquid desorption ion source and solvent extraction

  9. 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.

  10. Alkaline-earth metal compounds. Oddities and applications

    International Nuclear Information System (INIS)

    This book contains the following six topics: heavy alkaline-earth metal organometallic and metal organic chemistry: synthetic methods and properties (Ana Torvisco, Karin Ruhlandt-Senge); Heavier group 2 Grignard reagents of the type aryl-ae(l)n-x post-Grignard reagents (Matthias Westerhausen, Jens Langer, Sven Krieck, Reinald Fischer, Helmar Goerls, Mathias Koehler); stable molecular magnesium(I) dimers: A fundamentally appealing yet synthetically versatile compound class (Cameron Jones, Andreas Stasch); Modern developments in magnesium reagent chemistry for synthesis (Robert E. Mulvey, Stuart D. Robertson); Alkaline-earth metal complexes in homogeneous polymerization catalysis (Jean-Francois Carpentier, Yann Sarazin); homogeneous catalysis with organometallic complexes of group 2 (Mark R. Crimmin, Michael S. Hill); Chiral Ca, Sr and Ba-catalyzed asymmetric direct-type aldol, Michael, and Mannich and related reactions (Tetsu Tsubogo, Yasuhiro Yamashita, Shu- Kobayashi).

  11. Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal

    Institute of Scientific and Technical Information of China (English)

    SONG Ming-zhi; ZHU Lan-ying; GAO Xi-ke; DOU Jian-min; SUN De-zhi

    2005-01-01

    Thermodynamic parameters of complexation of naphto- 15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.

  12. EXAFS investigations of earth-alkaline metal uranyl tri-carbonate complexes

    International Nuclear Information System (INIS)

    Carbonate and bicarbonate are the common anions found in significant concentrations in many natural waters, and are exceptionally strong complexation agents for actinide ions. Seepage, flooding and mining waters from the uranium mining area in the south-east of Germany (Saxony and Thuringia) contain relatively high amounts of magnesium, calcium, carbonate and sulphate ions. In these waters the pH values range from 7.0 to 8.0 and the uranium content is about 0.02 mmol/L where magnesium, calcium and carbonate concentrations are 11.6 mmol/L, 6.9 mmol/L and 3.9 mmol/L, respectively. The existence of the natural complexes Ca2UO2(CO3)3(aq) and Mg2UO2(CO3)3(aq) were recently able to be confirmed by spectroscopic measurements. We performed extended X-ray absorption fine structure (EXAFS) measurements at the uranium LIII-edge to study the structures of these complexes. The results obtained from these complex solutions are compared with those from the corresponding EXAFS and XRD data related to the secondary minerals of uranium, liebigite, Ca2[UO2(CO3)3] . 10 H2O and bayleyite, Mg2[UO2(CO3)3]-10 H2O and they are in good agreement. (authors)

  13. Phisicochemistry of alkaline-earth metals oxides surface

    Science.gov (United States)

    Ekimova, Irina; Minakova, Tamara; Ogneva, Tatyana

    2016-01-01

    The surface state of alkaline-earth metals and magnesium oxides obtained by means of commercial and laboratory ways has been studied in this paper. A complex of methods has been used for identification, determination of a phase composition and morphology of the samples. The high basic character of surface centres has been shown with the help of pH-metry and adsorption of indicators methods. Acid-basic parameters (pHt, pHiis, etc.) can be used for the estimation of a general acid-basic state of metal oxides samples surface and for the supposition about different nature and strength of acid-basic centres as well as for the initial control in the process of acid basic properties of solid oxides surface properties evaluation.

  14. Solvent Extraction of Alkaline Earth Metals with Alkylphosphorus Acids

    Institute of Scientific and Technical Information of China (English)

    XUXin; ZHUTun

    2002-01-01

    Solvent extraction equiliria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester, di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent of the e/r value and hydration energy of the metal ions. The minor shift of the P→O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P→O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compunds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effects is explained by using IR spectra of the loaded organic phase.

  15. THE TRANSFER OF ALKALINE EARTH-METAL ION AT W/NB INTERFACE FACILITATED BY JOSAMYCIN

    Institute of Scientific and Technical Information of China (English)

    范瑞溪; 狄俊伟

    1991-01-01

    This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential cyclic voltammetry .The peak height is directly proportional to the concentration of josaycin (nb) and to the potential scan rate.The complexes formed from alkaline earth-metal ions and josamycin at the w/nb interface are ML22+ ion.

  16. Solubility of fluorides of alkaline earth metals and some rare earths in anhydrous trifluoroacetic acid

    International Nuclear Information System (INIS)

    Solubility of fluorides of alkaline earth and some rare earth metals in anhydrous trifluoroacetic acid is studied. For each type of fluoride solubility depends on the ionic radius of the cation. Solubility of fluorides of alkaline earth metals grows from magnesium to barium. All the fluorides in anhydrous trifluoroacetic acid form solvates. Solvates of strontium and scandium fluorides are shown to decompose at 110 and 150 deg C respectively

  17. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting...

  18. The low temperature radiolysis of cis-syn-cis-dicyclohexano-18-crown-6 complexes with alkaline earth metal nitrates: An evidence for energy transfer to the macrocyclic ligand

    Science.gov (United States)

    Zakurdaeva, O. A.; Nesterov, S. V.; Shmakova, N. A.; Sokolova, N. A.; Feldman, V. I.

    2015-10-01

    Formation of paramagnetic intermediates in macrocyclic complexes of cis-syn-cis-dicyclohexano-18-crown-6 (DCH18C6) with alkaline earth metal nitrates under X-rays irradiation was studied by EPR spectroscopy. NO32- dianions appear to be predominant intermediate species in the samples irradiated at 77 K at low doses (up to 40 kGy). This result was interpreted as an evidence for energy transfer within the complex from crown ether to nitrate anion. Increase in the absorbed dose from 40 kGy to 284 kGy results in built-up of a new EPR signal assigned to macrocyclic -CH2-ĊH-O- radicals produced from crown ether moieties. Thermal annealing of the irradiated macrocyclic complexes at 273 К led to fast decay of NO32- . This process was accompanied by a formation of -CH2-ĊH-O- radicals in secondary reactions. The nature of the metal cations coordinated in the macrocycle cavity had no appreciable effect on the composition of radical products and their post-radiation transformations.

  19. Structural variations in layered alkaline earth metal cyclohexyl phosphonates

    Indian Academy of Sciences (India)

    Ramaswamy Murugavel; Nayanmoni Gogoi

    2009-06-01

    Two series of alkaline earth metal cyclohexyl phosphonates, M(C6H11PO3H)2(H2O) (M = Ca, Sr and Ba) (1–3) and M(C6H11PO3)(H2O) (M = Mg, Ca, Sr, and Ba) (4–7) have been synthesized under mild reaction conditions. All new compounds have been characterized using elemental analysis, IR, TGA and powder X-ray diffraction techniques. The molecular structure of compound 2 determined using single crystal X-ray diffraction technique reveals a layered polymeric structure.

  20. Mixed ligand complexes of alkaline earth metals: Part XII. Mg(II, Ca(II, Sr(II and Ba(II complexes with 5-chlorosalicylaldehyde and salicylaldehyde or hydroxyaromatic ketones

    Directory of Open Access Journals (Sweden)

    MITHLESH AGRAWAL

    2002-04-01

    Full Text Available The reactions of alkaline earth metal chlorides with 5-chlorosalicylaldehyde and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been carried out in 1 : 1 : 1 mole ratio and the mixed ligand complexes of the type MLL’(H2O2 (where M = Mg(II, Ca(II, Sr(II and Ba(II, HL = 5-chlorosalicylaldehyde and HL’ = salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been isolated. These complexes were characterized by TLC, conductance measurements, IR and 1H-NMR spectra.

  1. Potassium salts of fatty acids as precipitating agents of alkaline earth metal ions

    International Nuclear Information System (INIS)

    Regularities have been studied of precipitation of ions of alkaline-earth elements with caprilate, pelargonate, caprinate, undecanate, laurate, tridecanate, myristate, pentadecanate, palmitate, and stearate of potassium. It has been shown that completeness of precipitation of metal ions is determined by the nature of alkaline-earth metal and potassium salt as well as by pH value and temperature of the solution. The study of temperature dependence of soaps of alkaline-earth metals makes it possible to calculate the heats of dissolution of laurates of alkaline-earth metals, and a change in entropy and free energy

  2. Alkali and alkaline earth metal salts of boron anionic complexes with o-hydroxy-benzyl alcohols (saligenin)

    International Nuclear Information System (INIS)

    Salts of two anionic boron complexes with 2 hydroxy-benzyl alcohol-[BA2- and [B(OH)2A]- - were synthesized. The first complex was separated in the form of anhydrous potassium and cesium salts, the second one - in the form of sodium (dihydrate), calcium (dihydrate) and barium (tetrahydrate and anhydrous salt) salts. Conditions of formation are discussed. Solubility in water and organic solvents, interplanar distances of crystal lattice were determined. The compounds were studied by the methods of infrared spectroscopy, thermal analysis. Hypothetical composition of the compounds is given

  3. Conversion of ethanol to propylene over HZSM-5 type zeolites containing alkaline earth metals

    OpenAIRE

    Goto, Daisuke; Harada, Yasumitsu; Furumoto, Yoshiyasu; Takahashi, Atsushi; Fujitani, Tadahiro; Oumi, Yasunori; Sadakane, Masahiro; Sano, Tsuneji

    2010-01-01

    Protonated ZSM-5 type zeolites containing alkaline earth metals (M-HZSM-5, M: alkaline earth metal) were prepared under various synthesis conditions and their catalytic performance in conversion of ethanol to light olefins was investigated in detail. Among M-HZSM-5, Sr-HZSM-5 exhibited an excellent performance.

  4. Triethanolaminelaurylsulfate as a collector for alkaline earth metal ions

    International Nuclear Information System (INIS)

    Basic features of flotation isolation of magnesium, calcium, strontium and barium ions, collected with the help of triethanolaminelaurylsulphate (TEALS) are described. The efficiency of the process depends on the nature of alkaline earth ions, on their concentration, on pH and temperature

  5. Helical ternary complexes of alkaline earth picrates with open-chain crown ether

    Institute of Scientific and Technical Information of China (English)

    刘伟生; 温永红; 刘雪原; 谭民裕

    2003-01-01

    Four solid complexes of alkaline earth picrates with N,N,N′,N′-tetraphenyl-3,6,9-tri- oxaundecanediamide (TTD), M (Pic)2TTD (1, M = Mg; 2, M = Ca; 3, M = Sr; 4, M = Ba), have been prepared and characterized by elemental analysis, conductivity measurement, IR spectra, 1H NMR spectra and TG-DTA techniques. Crystal structure of complex 3 shows that the Sr(Ⅱ) ion is 9-coordinated by five oxygen atoms from TTD and four oxygen atoms from two bidentate picrates, and the coordination polyhedron is distorted tricapped trigonal prism. TTD as a pentadentate ligand forms a right-handed helical coordination structure. The chelating helical chain has a relative fixed radius and then shows a high coordination selectivity to metal ion. The high selectivity of TTD to alkaline earth ions is explained elementarily from the special coordination structures.

  6. Facilitated transport of alkaline and alkaline earth metals through liquid membranes with acidic extractants

    International Nuclear Information System (INIS)

    The removal of radioactive Cs and Sr from the liquid waste of nuclear plants is an important problem for both the defense arid the energy industries. Experiments with bulk liquid membranes and liquid membranes, immobilized on porous support, demonstrated the applicability of these systems for active transport of alkaline cations and Sr from alkaline to acidic solution against the concentration gradient of the metal. The mechanism of transport facilitated by fatty acids for alkali metals, or by di-2-ethylhexyl phosphoric acid for Sr in the presence of Ca and EDTA, corresponds to the open-quotes big carrouselclose quotes model, according to which the carrier is distributed between the membrane and aqueous solutions, where metal/H+- ion exchange takes place. The rate limiting step is the reextraction of Sr from the membrane into the acceptor (acidic) solution and is determined by the diffusion of the protonated carrier from the stripping acidic solution through the corresponding unstirred layer

  7. Calculated Structural Phase-Transitions in the Alkaline-Earth Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1982-01-01

    The local-density approximation and the linear muffin-tin orbital method have been used within the atomic-sphere approximation to calculate structural energy differences for all the alkaline earth metals at zero temperature. At ordinary pressure the calculations predict the crystal structure...

  8. New MOFs based on taurine-N,N-(bismethylphosphonates) of alkalineearth metals

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jan; Melánová, Klára; Zima, Vítězslav; Beneš, L.; Vlček, Milan; Raja, D. S.; Lin, C. H.

    Strasbourg: University of Strasbourg, Francie, 2015. P63. [ISIC18 International Symposium on Intercalation Compounds. 31.05.2015-04.06.2015, Strasbourg] Grant ostatní: AV ČR(CZ) M200501202 Institutional support: RVO:61389013 Keywords : taurine * single crystal diffraction * alkaline earth metal - organic frameworks Subject RIV: CC - Organic Chemistry

  9. Adsorption of Alkali, Alkaline Earth and Transition Metal Atoms on Silicene

    OpenAIRE

    Sahin, Hasan; Peeters, Francois M.

    2013-01-01

    The adsorption characteristics of alkali, alkaline earth and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon, are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, workfuncti...

  10. Tryptophan fluorescence quenching by alkaline earth metal cations in deionized bacteriorhodopsin.

    Science.gov (United States)

    Wang, G; Wang, A J; Hu, K S

    2000-12-01

    Tryptophan quenching by the addition of alkaline earth metal cations to deionized bacteriorhodopsin suspensions was determined. The results show that the addition of cation primarily quenches fluorescence from surface tryptophan residues. The quenched intensity exhibits a 1/R dependence, where R is the ionic radius of the corresponding metal ion. This observation results from a stronger energy transfer coupling between the tryptophan and the retinal. The membrane curvature may be involved as a result of cations motion and correlated conformational changes. PMID:11332888

  11. Conformation Switching in Gas-Phase Complexes of Histidine with Alkaline Earth Ions

    NARCIS (Netherlands)

    Dunbar, R. C.; Hopkinson, A. C.; Oomens, J.; Siu, C. K.; Siu, K. W. M.; Steill, J. D.; Verkerk, U. H.; Zhao, J. F.

    2009-01-01

    Infrared multiple photon dissociation spectroscopy of gas-phase doubly charged alkaline earth complexes of histidine reveals a transition from dominance of the zwitterion (salt bridge, SB) conformation with Ba2+ to substantial presence of the canonical (charge-solvated, CS) conformation with Ca2+. T

  12. Preparation of decarboxylic-functionalized weak cation exchanger and application for simultaneous separation of alkali, alkaline earth and transition metals.

    Science.gov (United States)

    Peng, Yahui; Gan, Yihui; He, Chengxia; Yang, Bingcheng; Guo, Zhimou; Liang, Xinmiao

    2016-06-01

    A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a "thiol-ene" click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water. PMID:27130093

  13. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    OpenAIRE

    Martínez, S.; Acción, F.; Puertas, F.

    1992-01-01

    Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide), employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium) allowed us to determine the Lambe...

  14. Uptake of alkaline earth metals in Alcyonarian spicules (Octocorallia)

    Science.gov (United States)

    Taubner, I.; Böhm, F.; Eisenhauer, A.; Garbe-Schönberg, D.; Erez, J.

    2012-05-01

    Alcyonarian corals (Octocorallia) living in shallow tropical seas produce spicules of high-Mg calcite with ˜13 mol% MgCO3. We cultured the tropical alcyonarian coral Rhythisma fulvum in experiments varying temperature (19-32 °C) and pH (8.15-8.44). Alkalinity depletion caused by spicule formation systematically varied in the temperature experiments increasing from 19 to 29 °C. Spicules were investigated for their elemental ratios (Mg/Ca, Sr/Ca) using ICP-OES, δ44/40Ca using TIMS, as well as δ18O and δ13C by IRMS. Mg/Ca increased with temperature from 146 to 164 mmol/mol, in good agreement with the range observed for marine inorganic calcite. Mg/Ca increased by 1.0 ± 0.4 mmol/mol/°C, similar to the sensitivity of Miliolid foraminifera. The pH experiments revealed a linear relationship between Mg/Ca and carbonate ion concentration of +0.03 ± 0.02 mmol/mol/μMol. Sr/Ca ranges from 2.5 to 2.9 mmol/mol being in good agreement with other high-Mg calcites. Temperature and pH experiments showed linear dependencies of Sr/Ca matching inorganic calcite trends and pointing to a decoupling of crystal precipitation rate and calcification rate. Ca isotopes range between 0.7‰ and 0.9‰ in good agreement with aragonitic scleractinian corals and calcitic coccoliths. Presumably Ca isotopes are fractionated by a biological mechanism that may be independent of the skeletal mineralogy. We observe no temperature trend, but a significant decrease of δ44/40Ca with increasing pH. This inverse correlation may characterise biologically controlled intracellular calcification. Oxygen isotope ratios are higher than expected for isotopic equilibrium with a temperature sensitivity of -0.15 ± 0.03‰/°C. Carbon isotope ratios are significantly lower than expected for equilibrium and positively correlated with temperature with a slope of 0.20 ± 0.04‰/°C. Many of our observations on trace element incorporation in R. fulvum may be explained by inorganic processes during crystal

  15. Aluminum/alkaline earth metal composites and method for producing

    Science.gov (United States)

    Russell, Alan M; Anderson, Iver E; Kim, Hyong J; Freichs, Andrew E

    2014-02-11

    A composite is provided having an electrically conducting Al matrix and elongated filaments comprising Ca and/or Sr and/or Ba disposed in the matrix and extending along a longitudinal axis of the composite. The filaments initially comprise Ca and/or Sr and/or Ba metal or allow and then may be reacted with the Al matrix to form a strengthening intermetallic compound comprising Al and Ca and/or Sr and/or Ba. The composite is useful as a long-distance, high voltage power transmission conductor.

  16. Molecular dynamics of liquid alkaline-earth metals near the melting point

    Indian Academy of Sciences (India)

    J K Baria; A R Jani

    2010-10-01

    Results of the studies of the properties like binding energy, the pair distribution function (), the structure factor (), specific heat at constant volume, velocity autocorrelation function (VACF), radial distribution function, self-diffusion coefficient and coordination number of alkaline-earth metals (Be, Mg, Ca, Sr and Ba) near melting point using molecular dynamics (MD) simulation technique using a pseudopotential proposed by us are presented in this article. Good agreement with the experiment is achieved for the binding energy, pair distribution function and structure factor, and these results compare favourably with the results obtained by other such calculations, showing the transferability of the pseudopotential used from solid to liquid environment in the case of alkaline-earth metals.

  17. Calculated Structural Phase-Transitions in the Alkaline-Earth Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1982-01-01

    The local-density approximation and the linear muffin-tin orbital method have been used within the atomic-sphere approximation to calculate structural energy differences for all the alkaline earth metals at zero temperature. At ordinary pressure the calculations predict the crystal structure sequ...... sequence hcp→fcc→bcc as a function of atomic number. As a function of pressure they predict the structure sequence fcc→bcc→hcp. The structural transitions and the onset of superconductivity under pressure are correlated with the d occupation number.......The local-density approximation and the linear muffin-tin orbital method have been used within the atomic-sphere approximation to calculate structural energy differences for all the alkaline earth metals at zero temperature. At ordinary pressure the calculations predict the crystal structure...

  18. Properties of the triplet metastable states of the alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    The static and dynamic properties of the alkaline-earth-metal atoms in their metastable state are computed in a configuration interaction approach with a semiempirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths, and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described

  19. Thermochemical study of gaseous oxy salts. Communication 7. Alkaline earth metal niobates

    International Nuclear Information System (INIS)

    Existence of gaseous niobates of alkaline-earth metals was ascertained by the method of high-temperature mass-spectrometry. Equilibrium constants involving the molecules and the relevant oxides were calculated, the standard enthalpies of formation and atomization for gaseous BeNbO3, CaNbO3, SrNbO3, BaNbO2, BaNbO3 and BaNb2O6 were determined

  20. Infrared absorption spectra of alkaline earth metal metaphosphates

    International Nuclear Information System (INIS)

    Infrared absorption spectra of Ba, Sr, Ca, Mg, Be metaphosphates in crystal and glass-like states are studied. Reference of absorption bands to the oscillations of the P=O, P-O- bonds and P-O-P bridges in complex anions is made. It is shown that α-Sr(PO3)2, β-Ca(PO3)0 and Be(PO3)2 are built of the [(POOsup(-)Osub(2/2))sub(4)] sub(infinity) chains of the C1 symmetry. According to spectral data calculated are the main characteristics of the P=o and P-O- bonds (force constants, bond order, interatomic distances). The main structural elements of glass-like metaphosphates are distorted (POO-Osub(2/2)) sub(infinity) chains connected in three-dimentional net

  1. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    International Nuclear Information System (INIS)

    Alkaline earth metal doped tin oxide (SnO2) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl4·5H2O and A(NO3)2·xH2O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO2 and A-doped SnO2 hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO2 hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m2 g−1 exhibited the considerably high OSC of 457 μmol-O g−1 and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material

  2. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae cho-7, Kofu 400-8511 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan)

    2015-09-15

    Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.

  3. An easy access to nanocrystalline alkaline earth metal fluorides - just by shaking

    Science.gov (United States)

    Dreger, M.; Scholz, G.; Kemnitz, E.

    2012-04-01

    High energy ball milling as fast, direct and solvent free method allows an easy access to nanocrystalline alkaline earth metal fluorides MF2 (M: Mg, Ca, Sr, Ba). Comparable metal sources (acetates, carbonates, hydroxides, alkoxides) were used for the reaction with NH4F as fluorinating agent. Even very simple manual shaking experiments between NH4F and the corresponding hydroxides in the stoichiometric ratio (M:F = 1:2, M: Ca, Sr, Ba) give phase pure fluorides. Moreover, comparable classical thermal reactions in closed crucibles at higher temperatures provide phase pure crystalline fluorides in nearly all cases as well.

  4. Validation of ion chromatography for the determination of transition metal ions along with alkali, alkaline earth metal elements for uranium oxide fuel

    International Nuclear Information System (INIS)

    The present report describes the use of Ion chromatography (IC) methods with spectrophotometric and direct conductivity detection for the determination of transition metal elements and alkali alkaline earth metal ions in UO2 pellets. Transmet analytical column and Metrosep- cation 1-2 column were used for the separation of transition metal elements and alkali and alkaline earth metal elements respectively. Oxalic acid and mixture of pyridine 2,6-dicarboxylic acid (PDCA), Na2SO4 and NaCl were used as mobile phase for the separation of transition metal ions and monitored after post - column reaction with 4,2-pyridylazo resorcinol (PAR) at 520nm spectrophotometrically. In the determination of alkali and alkaline earth metal ions the interference of transition metals are removed by complexing them with PDCA. Mixture of tartaric acid and PDCA employed in the separation of alkali and alkaline earth metal ions and monitored on direct conductivity detector. Mobile phase composition was optimised for the base line separation. Calibration plots of Fe3+, Cu2+, Ni2+, Co2+, Cd2+, Mn2+, Li+, Na+, K+, Mg2+, Ca2+ and Sr2+ were linear over a wide dynamic range with regression coefficient better than 0.999. Detection limit of above ions were between 5-30ppb. To prevent the overloading of the cation exchange column, uranium matrix was removed from UO2 sample by solvent extraction with 30% TBP - TOPO/CCl4. Ten sintered UO2 pellets of same lot were analysed and R.S.D. ±10% was obtained. These methods were validated by analysis of ILCE standards of UO2. (author)

  5. Apparent molar volumes and compressibilities of alkaline earth metal ions in methanol and dimethylsulfoxide

    Energy Technology Data Exchange (ETDEWEB)

    Warminska, Dorota, E-mail: dorota@chem.pg.gda.p [Department of Physical Chemistry, Chemical Faculty, Gdansk University of Technology, 80-233 Gdansk (Poland); Wawer, Jaroslaw; Grzybkowski, Waclaw [Department of Physical Chemistry, Chemical Faculty, Gdansk University of Technology, 80-233 Gdansk (Poland)

    2010-09-15

    Temperature dependencies of density of magnesium (II), calcium (II), strontium (II), barium (II) perchlorates as well as beryllium (II), and sodium trifluoromethanesulfonates in methanol and dimethylsulfoxide have been determined over the composition range studied. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of alkaline earth metal perchlorates and beryllium (II) and sodium triflates in methanol and DMSO have been calculated from sound speed data obtained at T = 298.15 K.

  6. Apparent molar volumes and compressibilities of alkaline earth metal ions in methanol and dimethylsulfoxide

    International Nuclear Information System (INIS)

    Temperature dependencies of density of magnesium (II), calcium (II), strontium (II), barium (II) perchlorates as well as beryllium (II), and sodium trifluoromethanesulfonates in methanol and dimethylsulfoxide have been determined over the composition range studied. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of alkaline earth metal perchlorates and beryllium (II) and sodium triflates in methanol and DMSO have been calculated from sound speed data obtained at T = 298.15 K.

  7. Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

    Science.gov (United States)

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-08-01

    Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

  8. Long-range interacting many-body systems with alkaline-earth-metal atoms

    CERN Document Server

    Olmos, B; Singh, Y; Schreck, F; Bongs, K; Lesanovsky, I

    2012-01-01

    Alkaline-earth-metal atoms exhibit long-range dipolar interactions, which are generated via the coherent exchange of photons on the 3P_0-3D_1-transition of the triplet manifold. In case of bosonic strontium, which we discuss here, this transition has a wavelength of 2.7 \\mu m and a dipole moment of 2.46 Debye, and there exists a magic wavelength permitting the creation of optical lattices that are identical for the states 3P_0 and 3D_1. This interaction enables the realization and study of mixtures of hard-core lattice bosons featuring long-range hopping, with tuneable disorder and anisotropy. We derive the many-body Master equation, investigate the dynamics of excitation transport and analyze spectroscopic signatures stemming from coherent long-range interactions and collective dissipation. Our results show that lattice gases of alkaline-earth-metal atoms permit the creation of long-lived collective atomic states and constitute a simple and versatile platform for the exploration of many-body systems with lon...

  9. Three-photon process for producing a degenerate gas of metastable alkaline-earth-metal atoms

    Science.gov (United States)

    Barker, D. S.; Pisenti, N. C.; Reschovsky, B. J.; Campbell, G. K.

    2016-05-01

    We present a method for creating a quantum degenerate gas of metastable alkaline-earth-metal atoms. This has yet to be achieved due to inelastic collisions that limit evaporative cooling in the metastable states. Quantum degenerate samples prepared in the 1S0 ground state can be rapidly transferred to either the 3P2 or 3P0 state via a coherent three-photon process. Numerical integration of the density-matrix evolution for the fine structure of bosonic alkaline-earth-metal atoms shows that transfer efficiencies of ≃90 % can be achieved with experimentally feasible laser parameters in both Sr and Yb. Importantly, the three-photon process can be set up such that it imparts no net momentum to the degenerate gas during the excitation, which will allow for studies of metastable samples outside the Lamb-Dicke regime. We discuss several experimental challenges to successfully realizing our scheme, including the minimization of differential ac Stark shifts between the four states connected by the three-photon transition.

  10. Ab Initio Calculation of 19F NMR Chemical Shielding for Alkaline-earth-metal Fluorides

    Institute of Scientific and Technical Information of China (English)

    CAI,Shu-Hui(蔡淑惠); CHEN,Zhong,(陈忠); LU,Xin(吕鑫); CHEN,Zhi-Wei(陈志伟); WAN,Hui-Lin(万惠霖)

    2001-01-01

    Gauge-independent atomic orbital (GIAO) method atHartree-Fock (HF) and density functional theory (DFr) lev-els,respectively,was employed to calculate 19F NMR chemi-cal shieldings of solid state alkaline-earth-metal fluorides MF2 (M = Mg,Ca,Sr,Ba).The results show that,although thecalculated19F chemical shieldings tend to be larger than the experinental values,they have a fairly good linear relation-ship with the observed ones.The calculated results based on different combinations of basis sets show that the B3LYP (ahybrid of DFT with HF) predictions are greatly superior tothe I-IF predictions.When a basis set of metal atom with ef- fecfive core potential (ECP) has well representation of valencewavefunction,especially wavefuncfion of d component,andproper definition of core electron nmnher,it can be applied toobtain 19F chemical shielding which is dose to that of all-elec-tron calculation.Tne variation of 19F chemical shielding of al-kaline-earth-metal fluorides correlates well with the latticefactor A/R2.``

  11. Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms - a new hope

    CERN Document Server

    Soldán, Pavel; Hutson, Jeremy M

    2009-01-01

    We explore the potential energy surfaces for NH molecules interacting with alkali-metal and alkaline-earth atoms using highly correlated ab-initio electronic structure calculations. The surfaces for interaction with alkali-metal atoms have deep wells dominated by covalent forces. The resulting strong anisotropies will produce strongly inelastic collisions. The surfaces for interaction with alkaline-earth atoms have shallower wells that are dominated by induction and dispersion forces. For Be and Mg the anisotropy is small compared to the rotational constant of NH, so that collisions will be relatively weakly inelastic. Be and Mg are thus promising coolants for sympathetic cooling of NH to the ultracold regime.

  12. Electric dipole polarizability of alkaline-Earth-metal atoms from perturbed relativistic coupled-cluster theory with triples

    CERN Document Server

    Chattopadhyay, S; Angom, D

    2014-01-01

    The perturbed relativistic coupled-cluster (PRCC) theory is applied to calculate the electric dipole polarizabilities of alkaline Earth metal atoms. The Dirac-Coulomb-Breit atomic Hamiltonian is used and we include the triple excitations in the relativistic coupled-cluster (RCC) theory. The theoretical issues related to the triple excitation cluster operators are described in detail and we also provide details on the computational implementation. The PRCC theory results are in good agreement with the experimental and previous theoretical results. We, then, highlight the importance of considering the Breit interaction for alkaline Earth metal atoms.

  13. Core-Shell Magneto-Optical Trap for Alkaline-Earth-Metal-Like Atoms

    CERN Document Server

    Lee, Jeongwon; Noh, Jiho; Mun, Jongchul

    2014-01-01

    We propose and demonstrate a new magneto-optical trap (MOT) for alkaline-earth-metal-like (AEML) atoms where the narrow $^{1}S_{0}\\rightarrow$$^{3}P_{1}$ transition and the broad $^{1}S_{0}\\rightarrow$$^{1}P_{1}$ transition are spatially arranged into a core-shell configuration. Our scheme resolves the main limitations of previously adopted MOT schemes, leading to a significant increase in both the loading rate and the steady state atom number. We apply this scheme to $^{174}$Yb MOT, where we show about a hundred-fold improvement in the loading rate and ten-fold improvement in the steady state atom number compared to reported cases that we know of to date. This technique could be readily extended to other AEML atoms to increase the statistical sensitivity of many different types of precision experiments.

  14. Calculation of the lowest electronic excitations of the alkaline earth metals using the relativistic polarization propagator

    Science.gov (United States)

    Brandt, Sven; Pernpointner, Markus

    2015-07-01

    In this work we use the recently implemented four-component polarization propagator for accurate single excitation calculations of alkaline earth metals and compare our results to experimental data. Various approximations to the Dirac-Coulomb Hamiltonian are additionally tested. In Ca spin-orbit coupling already leads to noticeable zero field splitting, which gradually increases for the heavier homologs finally invalidating the singlet and triplet state characterizations. For all systems we observe a very good agreement with experimental transition energies in the considered energy range. For Sr, Ba and Ra non-relativistic approaches already exhibit unacceptable deviations in the reproduction of transition energies and spectral structure. The obtained excited final states are analyzed in terms of atomic donor and acceptor orbital contributions. Our results stress the necessity to use relativistic implementations of the polarization propagator for an accurate description of both electron correlation and relativistic effects contributing to excitation spectra of heavy systems.

  15. Permanent electric dipole moments of alkaline-earth-metal monofluorides: Interplay of relativistic and correlation effects

    Science.gov (United States)

    Prasannaa, V. S.; Sreerekha, S.; Abe, M.; Bannur, V. M.; Das, B. P.

    2016-04-01

    The interplay of the relativistic and correlation effects in the permanent electric dipole moments of the X 2Σ+ electronic ground states of the alkaline-earth-metal monofluorides (BeF, MgF, CaF, SrF, and BaF) has been studied using a relativistic coupled cluster method. The calculations were carried out using double, triple, and quadruple zeta basis sets, and with no core orbitals frozen. The results are compared with those of other calculations available in the literature and with experiments. The correlation trends in the permanent electric dipole moments of these molecules are discussed in detail. This information will be useful in throwing light on the interplay between relativistic and correlation effects of other properties that are relevant to fundamental physics.

  16. Influence of base strength on the catalytic performance of nano-sized alkaline earth metal oxides supported on carbon nanofibers

    NARCIS (Netherlands)

    Frey, A.M.; Yang, J.; Feche, C.; Essayem, N.; Stellwagen, D.R.; Figueras, F.; Jong, de K.P.; Bitter, J.H.

    2013-01-01

    Nano-sized (3 nm) alkaline earth metal oxides supported on carbon nanofibers were prepared by a facile impregnation and heat treatment method of the corresponding nitrates. These supported catalysts showed a significant improved activity for the aldol reaction and transesterification compared to the

  17. Electric dipole polarizabilities at imaginary frequencies for the alkali-metal, alkaline-earth, and inert gas atoms

    CERN Document Server

    Derevianko, Andrei; Babb, James F

    2009-01-01

    The electric dipole polarizabilities evaluated at imaginary frequencies for hydrogen, the alkali-metal atoms, the alkaline earth atoms, and the inert gases are tabulated along with the resulting values of the atomic static polarizabilities, the atom-surface interaction constants, and the dispersion (or van der Waals) constants for the homonuclear and the heteronuclear diatomic combinations of the atoms.

  18. Semiempirical calculation of van der Waals coefficients for alkali-metal and alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    The van der Waals coefficients, C6, C8, and C10 for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, D8 and the three-body coefficient, C9 are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution

  19. Dispersion coefficients for H and He interactions with alkali-metal and alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    The van der Waals coefficients C6, C8, and C10 for H and He interactions with the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are determined from oscillator strength sum rules. The oscillator strengths were computed using a combination of ab initio and semiempirical methods. The dispersion parameters generally agree with close to exact variational calculations for Li-H and Li-He at the 0.1% level of accuracy. For larger systems, there is agreement with relativistic many-body perturbation theory estimates of C6 at the 1% level. These validations for selected systems attest to the reliability of the present dispersion parameters. About half the present parameters lie within the recommended bounds of the Standard and Certain compilation [J. Chem. Phys. 83, 3002 (1985)

  20. Alkaline-earth metal phosphonocarboxylates: synthesis, structures, chirality, and luminescence properties

    Czech Academy of Sciences Publication Activity Database

    Zima, Vítězslav; Raja, D. S.; Lee, Y. S.; Chang, T. G.; Wu, Ch. Y.; Hu, Ch. Ch.; Lee, K. R.; Lai, J. Y.; Yeh, J. M.; Lin, Ch. H.

    2013-01-01

    Roč. 42, č. 43 (2013), s. 15332-15342. ISSN 1477-9226 Grant ostatní: AV ČR(CZ) M200501202 Institutional support: RVO:61389013 Keywords : coordination polymers * phosphonates * alkaline-earth Subject RIV: CA - Inorganic Chemistry Impact factor: 4.097, year: 2013

  1. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    Directory of Open Access Journals (Sweden)

    Martínez, S.

    1992-09-01

    Full Text Available Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide, employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium allowed us to determine the Lambert-Beer law slopes for each compound. These values are differents (bearing in mind experimental random errors, so we have could to affirm the nonexistence of solid solution between the nitrate and the alkaline halide médium. The L-B law obtained by us can be used for the Identification differentiation and quantitative analysis of these nitrates in solid phase, even if they are present in a very low concentration.

    Se ha realizado la asignación de los espectros infrarrojo (IR de los nitratos alcalinos, sódico y potásico, y de los alcalinotérreos, magnésico y cálcico, en estado sólido. Se ha visto la influencia del medio dispersante (haluro alcalino, utilizado en la preparación de la muestra sólida. El estudio cuantitativo de la absorbencia de la banda a 1.387 cm-1 (presente en los espectros IR de los cuatro nitratos en medio KBr permite determinar las pendientes de la Ley de Lambert-Beer Se comprueba que dichas pendientes son diferentes lo que conduce a poder afirmar que no se produce disolución sólida entre el KBr y el nitrato alcalino o alcalinotérreo. La determinación de la ley de Lambert-Beer permite la identificación y el análisis cualitativo y cuantitativo por espectroscopia IR de estos nitratos cuando están presentes en bajas concentraciones en muestras sólidas.

  2. Thermodynamic properties of titanates, zirconates and hafnates of alkaline earth metals

    International Nuclear Information System (INIS)

    The problems are considered arising in critical analysis and choosing recommended values of thermodynamic constants of the series of the most important perovskites-ferroelectrics-titanates, zirconates, and hafnates of alkaline-earth metals finding application in modern radioelectronics. Recommended values of standard thermodynamic values are given: heat capacity Csub(p,298) , enthalpy change H298-H0, entropy S298, heat formation ΔHsub(f,298 ), free energy formation ΔGsub(f,298) , temperatures and heats of phase transitions with indication of errors for the adopted values. The effect of impurities on thermal constants of phase transitions is discussed. The relationships between thermodynamic characteristics of perovskites and crystal structure as well as the effect of orthorhombic distortions of ideal perovskite lattice on entropy of the compounds have been considered. Along with thermodynamic methods of investigation, a great attention is given to other physical methods which have been used for finding temperature regions of phase transitions, Curie points, and temperatures of transition from ferroelectric to paraelectric state. The importance of physical methods is emphasized in those cases when phase transitions are accompanied by small energy changes and are not fixed in measuring heat capacity

  3. Red-emitting alkaline-earth rare-earth pentaoxometallates powders prepared by metal carboxylates solution

    Indian Academy of Sciences (India)

    Kyu-Seog Hwang; Sung-Dae Kim; Seung Hwangbo; Jin-Tae Kim

    2013-06-01

    Moisture-insensitive metal carboxylates that are mostly liquids at room temperature have been first applied to the preparation of strontium europium aluminate (Sr2EuAlO5) powders for red-emitting phosphor under near ultraviolet radiation. Strontium naphthenate, aluminium-2-ethylhexanoate and europium-2-ethylhexanoate were dissolved with toluene to prepare starting solution. Precursor pyrolyzed at 500 °C for 240 min was finally annealed at 900–1200 °C for 240 min in Ar. X-ray diffraction analysis, field emission–scanning electron microscope and fluorescent spectrophotometer were used to evaluate structural and optical properties. For the 1000 °C-annealed powders with regular shape and narrow size distribution confirmed by FE–SEM observation, strong red emission at 615nm under the excitation of 395nm maximum was reached, then the higher annealed samples at above 1100 °C gave the lower emission intensities.

  4. Preparing poly(aryl ethers) using alkaline earth metal carbonates, organic acid salts, and optionally copper compounds, as catalysts

    International Nuclear Information System (INIS)

    This patent describes an improved process for preparing poly(aryl ethers) and poly(aryl ether ketones) by the reaction of a mixture of at least one bisphenol and at least one dihalobenzenoid compound, and/or a halophenol. The improvement comprises providing to the reaction, a base which is a combination of an alkaline earth metal carbonate and/or bicarbonate and a potassium, rubidium, or cesium salt of an organic acid or combination of organic salts thereof

  5. Preparing poly(aryl ethers) using alkaline earth metal carbonates, organic acid salts, and optionally copper compounds, as catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Winslow, P.A.; Kelsey, D.R.; Matzner, M.

    1988-09-27

    This patent describes an improved process for preparing poly(aryl ethers) and poly(aryl ether ketones) by the reaction of a mixture of at least one bisphenol and at least one dihalobenzenoid compound, and/or a halophenol. The improvement comprises providing to the reaction, a base which is a combination of an alkaline earth metal carbonate and/or bicarbonate and a potassium, rubidium, or cesium salt of an organic acid or combination of organic salts thereof.

  6. Long-range interactions between the alkali-metal atoms and alkaline earth ions

    CERN Document Server

    Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K

    2014-01-01

    Accurate knowledge of interaction potentials among the alkali atoms and alkaline earth ions is very useful in the studies of cold atom physics. Here we carry out theoretical studies of the long-range interactions among the Li, Na, K, and Rb alkali atoms with the Ca$^+$, Ba$^+$, Sr$^+$, and Ra$^+$ alkaline earth ions systematically which are largely motivated by their importance in a number of applications. These interactions are expressed as a power series in the inverse of the internuclear separation $R$. Both the dispersion and induction components of these interactions are determined accurately from the algebraic coefficients corresponding to each power combination in the series. Ultimately, these coefficients are expressed in terms of the electric multipole polarizabilities of the above mentioned systems which are calculated using the matrix elements obtained from a relativistic coupled-cluster method and core contributions to these quantities from the random phase approximation. We also compare our estim...

  7. Accumulation of alkaline earth metals by the green macroalga Bryopsis maxima.

    Science.gov (United States)

    Takahashi, Shigekazu; Aizawa, Kyoko; Nakamura, Saki; Nakayama, Katsumi; Fujisaki, Shingo; Watanabe, Soichiro; Satoh, Hiroyuki

    2015-04-01

    Twenty-five days after the disaster at the Fukushima Daiichi nuclear power plant in 2011, we collected samples of the green macroalga Bryopsis maxima from the Pacific coast of Japan. Bryopsis maxima is a unicellular, multinuclear, siphonous green macroalga. Radiation analysis revealed that B. maxima emitted remarkably high gamma radiation of (131)I, (134)Cs, (137)Cs, and (140)Ba as fission products of (235)U. Interestingly, B. maxima contained naturally occurring radionuclides derived from (226)Ra and (228)Ra. Analysis of element content revealed that B. maxima accumulates many ocean elements, especially high quantities of the alkaline earth metals Sr (15.9 g per dry-kg) and Ba (3.79 g per dry-kg), whereas Ca content (12.5 g per dry-kg) was lower than that of Sr and only 61 % of the mean content of 70 Japanese seaweed species. Time-course analysis determined the rate of radioactive (85)Sr incorporation into thalli to be approximately 0.13 g Sr per dry-kg of thallus per day. Subcellular fractionation of B. maxima cells showed that most of the (85)Sr was localized in the soluble fraction, predominantly in the vacuole or cytosol. Given that (85)Sr radioactivity was permeable through a dialysis membrane, the (85)Sr was considered to be a form of inorganic ion and/or bound with a small molecule. Precipitation analysis with sodium sulfate showed that more than 70% of the Sr did not precipitate as SrSO4, indicating that a proportion of the Sr may bind with small molecules in B. maxima. PMID:25744028

  8. Influence of doping with alkaline earth metals on the optical properties of thermochromic VO2

    Science.gov (United States)

    Dietrich, Marc K.; Kramm, Benedikt G.; Becker, Martin; Meyer, Bruno K.; Polity, Angelika; Klar, Peter J.

    2015-05-01

    Thin films of doped VO2 were deposited, analyzed, and optimized with regard to their solar energy transmittance (Tsol) and visible/luminous light transmittance (Tlum) which are important parameters in the context of smart window applications in buildings. The doping with alkaline earth metals (AEM) like Mg, Ca, Sr, or Ba increased both Tsol and Tlum due to a bandgap widening and an associated absorption edge blue-shift. Thereby, the brown-yellowish color impression of pure VO2 thin films, which is one major hindrance limiting the usage of VO2 as thermochromic window coating, was overcome. Transparent thin films with excellent switching behavior were prepared by sputtering. Highly doped V1-xMexO2 (Me = Ca, Sr, Ba) kept its excellent thermochromic switching behavior up to x(Me) = Me/(Me + V) = 10 at. % doping level, while the optical bandgap energy was increased from 1.64 eV for undoped VO2 to 2.38 eV for x(Mg) = 7.7 at. %, 1.85 eV for x(Ca) = 7.4 at. %, 1.84 eV for x(Sr) = 6.4 at. % and 1.70 eV for x(Ba) = 6.8 at. %, as well as the absorption edge is blue shifted by increasing AEM contents. Also, the critical temperature ϑc, at which the semiconductor-to-metal transition (SMT) occurs, was decreased by AEM doping, which amounted to about -0.5 K/at. % for all AEM on average. The critical temperature was determined by transmittance-temperature hysteresis measurements. Furthermore, Tsol and Tlum were calculated and were found to be significantly enhanced by AEM doping. Tlum increased from 32.0% in undoped VO2 to 43.4% in VO2 doped with 6.4 at. % Sr. Similar improvements were found for other AEM. The modulation of the solar energy transmittance ΔTsol, which is the difference of the Tsol values in the low and high temperature phase, was almost constant or even slightly increased when the doping level was increased up to about 10 at. % Ca, Sr, or Ba.

  9. Supramolecular structures constructed from three novel rare earth metal complexes

    Indian Academy of Sciences (India)

    Huaze Dong; Xiaojun Feng; Xia Liu; BiN Zheng; Jianhong Bi; Yan Xue; Shaohua Gou; Yanping Wang

    2015-05-01

    Three rare earth metal supramolecular complexes, {[Tb(2)4](ClO4)3·2H2O(1), [Eu(2)2(H2O)5] (ClO4)3(2) and [Gd(NO3)3(2)2]·2CH3CH2OH(3) ( 2 = 3-Dimethylamino-1-pyridin-2-yl-propenone), have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. The crystal structure analysis reveals that the coordination numbers of three complexes (1–3) are 8, 9 and 10, respectively. Three complexes assembled into 3D frameworks based on C-H⋯O, O-H⋯O hydrogen bond linkages.

  10. Effect of doping TiO2 with alkaline-earth metal ions on its photocatalytic activity

    Directory of Open Access Journals (Sweden)

    YUEXIANG LI

    2007-04-01

    Full Text Available TiO2 photocatalysts doped with alkaline-earth metal ions were prepared by the impregnation and coprecipitation methods. The sample were characterized by XRD, XPS and IR spectroscopy. Their activities were evaluated by the photocatalytic production of hydrogen. The activities of the doped photocatalysts dopended on the size of the dopant ions and the dopingmethod. The optimum molar contents of dopant ions Be2+, Mg2+, Ca2+, Sr2+, Ba2+ were 1.25, 1.25, 2.25, 2.25 and 2.25 at. %, respectively. The optimum calcination temperature and time were 400 °C and 1 h.

  11. Main group chemistry of 9-hydroxophenalenone: Syntheses and structural characterization of the alkaline earth and zinc complexes

    Indian Academy of Sciences (India)

    Arup Mukherjee; Prinson P Samuel; Carola Schulzke; Swadhin K Mandal

    2014-09-01

    Herein, we report the synthesis and characterization of 9-hydroxophenalenone based alkaline earth and zinc complexes.The reaction of 9-hydroxophenalenone (HO,O-PLY (1)) with one equivalent of KN(SiMe3)2 and MI2 in THF yields heteroleptic complexes [(O,O-PLY)M(THF)]I [M= Mg (2), Ca (3), Sr (4), Ba (5); n = 1-4], while use of two equivalents of KN(SiMe3)2 in THF (with respect to PLY) produces homoleptic complex (O,O-PLY)2Mg(THF)2 (6). Moreover, reaction between two equivalents of 1 with one equivalent of ZnMe2 in THF produces complex (O,O-PLY)2Zn(THF)2 (7). All these complexes were characterized by NMR spectroscopy and elemental analyses. The solid state structures of complexes 2, 6 and 7 were established by single crystal X-ray diffraction analysis.

  12. State-dependent lattices for quantum computing with alkaline-earth-metal atoms

    CERN Document Server

    Daley, Andrew J; Zoller, Peter

    2011-01-01

    Recent experimental progress with Alkaline-Earth atoms has opened the door to quantum computing schemes in which qubits are encoded in long-lived nuclear spin states, and the metastable electronic states of these species are used for manipulation and readout of the qubits. Here we discuss a variant of these schemes, in which gate operations are performed in nuclear-spin-dependent optical lattices, formed by near-resonant coupling to the metastable excited state. This provides an alternative to a previous scheme [A. J. Daley, M. M. Boyd, J. Ye, and P. Zoller, Phys. Rev. Lett 101, 170504 (2008)], which involved independent lattices for different electronic states. As in the previous case, we show how existing ideas for quantum computing with Alkali atoms such as entanglement via controlled collisions can be freed from important technical restrictions. We also provide additional details on the use of collisional losses from metastable states to perform gate operations via a lossy blockade mechanism.

  13. Effect of mixed-ligand complex formation on the volatility of alkaline-earth element β-diketonates

    International Nuclear Information System (INIS)

    Some aspects of effect of heteroligand complexing on structure, thermal stability and volatility of β-diketonates of alkaline earth elements are considered using own and literature data. Radius of M2+ ion increases from 0.99 up to 1.34 A in the Ca-Sr-Ba row and strength and coordination numbers of forming associates increase. The strength of molecular associates decreases and volatility increases when degree of branching and degree of fluorination of alkyl radicals in β-diketonate ligands increase

  14. Frontier Orbital Engineering of Metal-Organic Frameworks with Extended Inorganic Connectivity: Porous Alkaline-Earth Oxides.

    Science.gov (United States)

    Hendon, Christopher H; Walsh, Aron; Dincă, Mircea

    2016-08-01

    The development of conductive metal-organic frameworks is challenging owing to poor electronic communication between metal clusters and the organic ligands that bridge them. One route to overcoming this bottleneck is to extend the inorganic dimensionality, while using the organic components to provide chemical functionality. Using density functional theory methods, we demonstrate how the properties of the alkaline-earth oxides SrO and BaO are transformed upon formation of porous solids with organic oxygen sources (acetate and trifluoroacetate). The electron affinity is significantly enhanced in the hybrid materials, while the ionization potential can be tuned over a large range with the polarity of the organic moiety. Furthermore, because of their high-vacuum fraction, these materials have dielectric properties suitable for low-κ applications. PMID:27267149

  15. Thermochemical study of gaseous oxy salts. Communication 11. Alkaline earth metal titanates

    International Nuclear Information System (INIS)

    Partial pressures of vapor components over systems MO-TiO2 (M = Be, Ca, Sr, Ba) were determined by the method of high-temperature mass spectrometry in the temperature range of ∼ 2180-2470 K and gas-phase equilibrium of reactions involving rare earth metal titanates were studied. For BeTiO3 and SrTiO3 molecules the standard formation and atomization enthalpies were determined, which at 298 K were -763 ± 22 and 2309 ± 23 kJ/mol, -868 ± 27 and 2249 ± 28 kJ/mol respectively

  16. Oxidation behavior of Cr(III) during thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides.

    Science.gov (United States)

    Mao, Linqiang; Gao, Bingying; Deng, Ning; Liu, Lu; Cui, Hao

    2016-02-01

    The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge. PMID:26650573

  17. Tuning magnetic properties of CrS{sub 2} monolayer by doping transition metal and alkaline-earth atoms

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianmin; Zheng, Huiling; Han, Ruilin; Du, Xiaobo; Yan, Yu, E-mail: yanyu@jlu.edu.cn

    2015-10-25

    In view of important role of inducing the magnetism in semiconducting transition metal dichalcogenides monolayer, the influences of a series of transition metal and alkaline-earth dopants, including Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd and In, on the electronic and magnetic properties of semiconducting CrS{sub 2} monolayer are systematically investigated using first-principles calculations. The calculations show that Nb, Mo, Ru and Rh dopants cannot induce the magnetism in doped CrS{sub 2} monolayer, whereas ground states of Ca, Sc, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Pd, Ag, Cd and In-doped system are magnetic and the stability of magnetic state of V doped system is small. Furthermore the value and the distribution of the magnetic moment induced by dopant not only relate to the number of valence electrons and the occupancy of the d orbitals of dopant, but also depend on the hybridization between dopant and its neighboring S and Cr atoms. Note that it is found that the substitutional doping at the Cr site of CrS{sub 2} monolayer with numerous transition metal and alkaline-earth atoms should be possible under the Cr-poor growth conditions. Overall, the calculated results show high potential for inducing the magnetism in CrS{sub 2} monolayer by doping at the Cr site. - Highlights: • The doping at the Cr site should be possible under the Cr-poor growth conditions. • Ca, Sc, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Pd, Ag, Cd and In dopants produce magnetism. • Ca, Sc, Ti, V, Zn, Ga, Sr, Y, Zr, Nb, Cd and In dopants result in p-type doping. • Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd and Ag dopants lead to n-type doping.

  18. MB82- (M=Be,Mg,Ca,Sr,and Ba):Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Complexes involving planar octacoordinate alkaline earth metal atoms in the centers of eight-membered boron rings have been investigated by two density functional theory (DFT) methods.BeB82-with D8h symmetry is predicted to be stable,both geometrically and electronically,since a good match is achieved between the size of the central beryllium atom and the eight-membered boron ring.By contrast,the other alkaline earth metal atoms cannot be stabilized in the center of a planar eight-membered boron ring because of their large radii.By following the out-of-plane imaginary vibrational frequency,pyramidal C8v MgB82-,CaB82-,SrB82-,and BaB82-structures are obtained.The presence of delocalized π and σ valence molecular orbitals in D8h BeB82-gives rise to aromaticity,which is reflected by the value of the nucleus-independent chemical shift.The D8h BeB82-structure is confirmed to be the global minimum on the potential energy surface.

  19. Solvent Extraction of Alkaline Earth Metals with Alkylphosphorus Acids%有机磷(膦)酸对碱土金属的萃取

    Institute of Scientific and Technical Information of China (English)

    许新; 朱屯

    2002-01-01

    Solvent extraction equilibria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester,di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent on the e/r value and hydration energy of the metal ions. The minor shift of the P-O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P-O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compounds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effect is explained by using IR spectra of the loaded organic phase.

  20. Electric dipole polarizabilities of doubly ionized alkaline Earth metal ions from perturbed relativistic coupled-cluster theory

    CERN Document Server

    Chattopadhyay, S; Angom, D

    2013-01-01

    Using perturbed relativistic coupled-cluster (PRCC) theory we compute the ground state electric dipole polarizability, $\\alpha$, of doubly ionized alkaline earth metal ions $\\rm{Mg}^{2+}$, $\\rm{Ca}^{2+}$, $\\rm{Sr}^{2+}$, $\\rm{Ba}^{2+}$ and $\\rm{Ra}^{2+}$. In the present work we use the Dirac-Coulomb-Breit atomic Hamiltonian and we also include the Uehling potential, which is the leading order term in the vacuum polarization corrections. We examine the correction to the orbital energies arising from the Uehling potential in the self-consistent field calculations as well as perturbatively. Our results of $\\alpha$ are in very good agreement with the experimental data, and we observe a change in the nature of the orbital energy corrections arising from the vacuum polarization as we go from $\\rm{Mg}^{2+}$ to Ra$^{2+}$.

  1. Colorimetric and bare-eye detection of alkaline earth metal ions based on the aggregation of silver nanoparticles functionalized with thioglycolic acid

    International Nuclear Information System (INIS)

    We describe a simple and rapid method for colorimetric and bare-eye detection of the alkaline earth metal ions Mg(II), Ca(II), Sr(II) and Ba(II) based on the use of silver nanoparticles (AgNPs) functionalized with thioglycolic acid (TGA). The TGA ligand was self-assembled onto the AgNPs to form a probe that undergoes a color change from yellow to orange or red on exposure to the alkaline earth ions. It is presumed that the color change is a result of the aggregation of the AgNPs caused by the interaction of the bivalent ions with the carboxy groups on the AgNPs. The color change can be used for bare-eye and colorimetric determination of the alkaline earth metal ions, for example to rapidly determine water hardness. (author)

  2. Structural, electronic and mechanical properties of alkaline earth metal oxides MO (M=Be, Mg, Ca, Sr, Ba)

    Science.gov (United States)

    Cinthia, A. Jemmy; Priyanga, G. Sudha; Rajeswarapalanichamy, R.; Iyakutti, K.

    2015-04-01

    The structural, electronic and mechanical properties of alkaline earth metal oxides MO (M=Be, Mg, Ca, Sr, Ba) in the cubic (B1, B2 and B3) phases and in the wurtzite (B4) phase are investigated using density functional theory calculations as implemented in VASP code. The lattice constants, cohesive energy, bulk modulus, band structures and the density of states are computed. The calculated lattice parameters are in good agreement with the experimental and the other available theoretical results. Electronic structure reveals that all the five alkaline earth metal oxides exhibit semiconducting behavior at zero pressure. The estimated band gaps for the stable wurtzite phase of BeO is 7.2 eV and for the stable cubic NaCl phases of MgO, CaO, SrO and BaO are 4.436 eV, 4.166 eV, 4.013 eV, and 2.274 eV respectively. A pressure induced structural phase transition occurs from wurtzite (B4) to NaCl (B1) phase in BeO at 112.1 GPa and from NaCl (B1) to CsCl (B2) phase in MgO at 514.9 GPa, in CaO at 61.3 GPa, in SrO at 42 GPa and in BaO at 14.5 GPa. The elastic constants are computed at zero and elevated pressures for the B4 and B1 phases for BeO and for the B1 and B2 phases in the case of the other oxides in order to investigate their mechanical stability, anisotropy and hardness. The sound velocities and the Debye temperatures are calculated for all the oxides using the computed elastic constants.

  3. Rare earth elements and titanium in plants, soils and groundwaters in the alkaline-ultramafic complex of Salitre, MG Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ceccantini, G. [Instituto de Biociencias, Sao Paulo, (Brazil). Dept. de Botanica; Figueiredo, A.M.G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radioquimica; Sondag, F.; Soubies, F. [ORSTOM, 93 - Bondy (France); Soubies, F. [Universite Paul Sabatier, 31 - Toulouse (France)

    1997-12-31

    The contents of rare earth elements (REE) and titanium in various plant species, in groundwaters and in soils from the alkaline-ultramafic complex of Salitre, have been determined. Due to the the particular mineralogy of the bedrock, REE and Ti exhibit high concentrations in the soils. Despite this, plants generally present REE concentrations within the ranges usually found in plants, and the transfer factor from soil to plant is at least ten times below the range reported in the literature, confirming that the concentrations of REE in the plants are widely independent of the soil content. All species present normalized patterns similar to those of the soils, characterized by an enrichment in light REE. Several plants show Ti concentrations about three times higher than the reference values. It is suggested that in the studied ecosystem, the plant metabolism affect the REE distribution in the groundwaters, leading to an enrichment of the superficial waters in heavy REE

  4. Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland

    Directory of Open Access Journals (Sweden)

    Jean-Michel Jaquet

    2013-10-01

    Full Text Available In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland, suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll a (Chl a concentration (2 mg m–3. Examination by scanning electron microscopy revealed the presence of numerous dark and gelatinous patches occluding the pores of the membranes, containing high numbers of picoplanktonic cells and, in places, clusters of high-reflectance smooth microspheres (1-2 μm in diameter. Their chemical composition, determined by semi-quantitative, energy-dispersive X ray spectroscopy (EDS showed magnesium (Mg, calcium (Ca, strontium (Sr and barium (Ba (alkaline earth metals to be the dominant cations. Among the anions, phosphorus (P and carbon (C were present, but only the latter is considered here (as carbonate. The microspheres were subdivided into four types represented in a Ca-Sr-Ba ternary space. All types are confined within a domain bound by Ca>45, Sr<10 and Ba<50 (in mole %. Type I, the most frequent, displays a broad variability in Ba/Ca, even within a given cluster. Types II and III are devoid of Ba, but may incorporate P. Type IV contains only Ca. The Type I composition resembles that of benstonite, a Group IIA carbonate that was recently found as intracellular granules in a cyanobacterium from alkaline lake Alchichica (Mexico.Lake Geneva microspheres are solid, featureless and embedded in a mucilage-looking substance in the vicinity of, but seemingly not inside, picoplanktonic cells morphologically similar to Chlorella and Synechococcus. In summer 2012, the macroscopic physico-chemical conditions in lake Geneva epilimnion were such as to allow precipitation of Ca but not of Sr and Ba carbonates. Favourable conditions did exist, though, in the micro-environment provided by the combination of active picoplankton and a mucilaginous envelope. Further studies are ongoing to investigate the

  5. Surface effect on the electronic and the magnetic properties of rock-salt alkaline-earth metal silicides

    International Nuclear Information System (INIS)

    An all electron ab-initio method was employed to study the electronic and the magnetic properties of the (001) surface of alkaline-earth metal silicides, CaSi, SrSi, and BaSi, in the rock-salt structure. The three compounds retain their ferromagnetic metallic properties at the surface. Due to the surface effects, the magnetism of the topmost layer is changed as compared with the bulk. This is a short-range effect. In CaSi, the magnetism of the surface layer is noticeably reduced, as compared with the bulk: magnetic moments (MMs) on both Ca and Si atoms are reduced. In SrSi (001), the polarization of electrons in the surface atoms is similar to that in the bulk atoms, and the values of MMs on the component atoms in the topmost layer do not change as much as in CaSi. In BaSi (001), the magnetic properties of Si surface atoms are enhanced slightly, and the magnetism of Ba atoms is not affected considerably by the surface effect. The calculated densities of states confirm the short-range effect of the surface on the electronic properties of the metal silicides.

  6. Enhanced NH3 gas sensing performance based on electrospun alkaline-earth metals composited SnO2 nanofibers

    International Nuclear Information System (INIS)

    Highlights: • The small-sized SnO2 (5–7 nm) were obtained by adding the alkaline-earth. • Sr-composited SnO2 nanofibers showed uniform nanotubes structure (Sr/SnO2). • Sr/SnO2 showed an excellent sensing performance to NH3 at room temperature. - Abstract: One-dimensional alkaline-earth metals composited SnO2 (Ae/SnO2) nanofibres were fabricated via electrospinning technique, followed by thermal treatment at 600 °C for 5 h. Transmission electron microscopy (TEM) studies showed that the nanoparticles size of Ae/SnO2 was 5–7 nm, which was smaller than the pristine SnO2 nanorods attached by 20 nm nanoparticles. Moreover, Sr/SnO2 nanocomposites showed uniform nanotubes structure with the wall thickness of about 30 nm, in which all the nanoparticles were connected to their neighbors by necks. The Sr/SnO2 nanotubes exhibited an excellent sensing response toward NH3 gas at room temperature, lower detection limit (10 ppm), faster response time (6 s towards 2000 ppm∼16 s towards 10 ppm) and better reversibility compared to the pristine SnO2 nanorods. The enhanced sensor performances were attributed to the higher conductivity of the Sr/SnO2. Mott–Schottky plots (M–S) and electrochemical impedance spectroscopy (EIS) measurements indicated that the carrier density of Sr/SnO2 nanotubes was 3 fold of that pristine SnO2

  7. Study of conformational and acid-base properties of norbadione A and pulvinic derivatives: Consequences on their complexation properties of alkaline and alkaline earth cations

    International Nuclear Information System (INIS)

    This work deals with the study of norbadione A, a pigment extracted from mushrooms and known to complex cesium cations. The study of the acid-base properties of norbadione A has allowed to determine the relative acidity of the seven protonable functions of the molecule and to reveal a reversible isomerization of the double exocyclic bond of the pulvinic moieties. The observed change of configuration is induced by a hydrogen bond of the H-O-H type and by electrostatic interactions. Moreover, the microscopic protonation mechanism of the norbadione A has been analyzed, considering three different study media where the acid-base properties of the norbadione A are compared. In the presence of 0.15 mol.l-1 of NaCl, it has been observed a remarkable cooperativity in the protonation of the enol groups. At last, the use of different analytical methods (NMR, potentiometry and calorimetry) has allowed to study the complexing properties of the norbadione A towards cesium and other alkaline and rare earth cations. (O.M.)

  8. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals

    OpenAIRE

    Liu, Yuanyue; Merinov, Boris V.; Goddard III, William A.

    2016-01-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same...

  9. Synthesis of a new family of ionophores based on aluminum-dipyrrin complexes (ALDIPYs) and their strong recognition of alkaline earth ions.

    Science.gov (United States)

    Saikawa, Makoto; Daicho, Manami; Nakamura, Takashi; Uchida, Junji; Yamamura, Masaki; Nabeshima, Tatsuya

    2016-03-14

    Mononuclear and dinuclear aluminum-dipyrrin complexes (ALDIPYs) were synthesized as a new family of ionophores. They exhibited colorimetric and fluorometric responses to alkaline earth ions in an aqueous mixed solvent. The strong recognition was achieved via multipoint interactions with the oxygen atoms appropriately incorporated into the ligand framework. PMID:26935409

  10. Dispersion coefficients for the interactions of the alkali-metal and alkaline-earth-metal ions and inert-gas atoms with a graphene layer

    Science.gov (United States)

    Kaur, Kiranpreet; Arora, Bindiya; Sahoo, B. K.

    2015-09-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients C3 of the alkali-metal ions Li+,Na+,K+, and Rb+, the alkaline-earth-metal ions Ca+,Sr+,Ba+, and Ra+, and the inert-gas atoms He, Ne, Ar, and Kr with a graphene layer are determined precisely within the framework of the Dirac model. For these calculations, we evaluate the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at room temperature.

  11. Effect of metal cation replacement on the electronic structure of metalorganic halide perovskites: Replacement of lead with alkaline-earth metals

    Science.gov (United States)

    Pazoki, Meysam; Jacobsson, T. Jesper; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

    2016-04-01

    Organic and inorganic lead halogen perovskites, and in particular, C H3N H3Pb I3 , have during the last years emerged as a class of highly efficient solar cell materials. Herein we introduce metalorganic halogen perovskite materials for energy-relevant applications based on alkaline-earth metals. Based on the classical notion of Goldschmidt's rules and quantum mechanical considerations, the three alkaline-earth metals, Ca, Sr, and Ba, are shown to be able to exchange lead in the perovskite structure. The three alkaline-earth perovskites, C H3N H3Ca I3,C H3N H3Sr I3 , and C H3N H3Ba I3 , as well as the reference compound, C H3N H3Pb I3 , are in this paper investigated with density functional theory (DFT) calculations, which predict these compounds to exist as stable perovskite materials, and their electronic properties are explored. A detailed analysis of the projected molecular orbital density of states and electronic band structure from DFT calculations were used for interpretation of the band-gap variations in these materials and for estimation of the effective masses of the electrons and holes. Neglecting spin-orbit effects, the band gap of MACa I3,MASr I3 , and MABa I3 were estimated to be 2.95, 3.6, and 3.3 eV, respectively, showing the relative change expected for metal cation exchange. The shifts in the conduction band (CB) edges for the alkaline-earth perovskites were quantified using scalar relativistic DFT calculations and tight-binding analysis, and were compared to the situation in the more extensively studied lead halide perovskite, C H3N H3Pb I3 , where the change in the work function of the metal is the single most important factor in tuning the CB edge and band gap. The results show that alkaline-earth-based organometallic perovskites will not work as an efficient light absorber in photovoltaic applications but instead could be applicable as charge-selective contact materials. The rather high CB edge and the wide band gap together with the large

  12. Optical probes for the detection of protons, and alkali and alkaline earth metal cations.

    Science.gov (United States)

    Hamilton, Graham R C; Sahoo, Suban K; Kamila, Sukanta; Singh, Narinder; Kaur, Navneet; Hyland, Barry W; Callan, John F

    2015-07-01

    Luminescent sensors and switches continue to play a key role in shaping our understanding of key biochemical processes, assist in the diagnosis of disease and contribute to the design of new drugs and therapies. Similarly, their contribution to the environment cannot be understated as they offer a portable means to undertake field testing for hazardous chemicals and pollutants such as heavy metals. From a physiological perspective, the Group I and II metal ions are among the most important in the periodic table with blood plasma levels of H(+), Na(+) and Ca(2+) being indicators of several possible disease states. In this review, we examine the progress that has been made in the development of luminescent probes for Group I and Group II ions as well as protons. The potential applications of these probes and the mechanism involved in controlling their luminescent response upon analyte binding will also be discussed. PMID:25742963

  13. Ion exchange kinetics of alkaline earth metals on acrylamide zirconium(IV) phosphate cation exchanger

    International Nuclear Information System (INIS)

    The kinetics of Mg(II), Ca(II), Sr(II) and Ba(II) exchange with H(I) on acrylamide zirconium(IV) phosphate has been studied applying the Nernst-Planck equation. The rate of exchange is found to be particle diffusion controlled at a metal ion concentration ≥ 0.01M in aqueous medium. The energy and entropy of activation vary linearly with the ionic radii and mobilities. (author)

  14. Oligomeric rare-earth metal cluster complexes with endohedral transition metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Simon; Zimmermann, Sina; Brühmann, Matthias; Meyer, Eva; Rustige, Christian; Wolberg, Marike; Daub, Kathrin; Bell, Thomas; Meyer, Gerd, E-mail: gerd.meyer@uni-koeln.de

    2014-11-15

    Comproportionation reactions of rare-earth metal trihalides (RX{sub 3}) with the respective rare-earth metals (R) and transition metals (T) led to the formation of 22 oligomeric R cluster halides encapsulating T, in 19 cases for the first time. The structures of these compounds were determined by single-crystal X-ray diffraction and are composed of trimers ((T{sub 3}R{sub 11})X{sub 15}-type, P6{sub 3}/m), tetramers ((T{sub 4}R{sub 16})X{sub 28}(R{sub 4}) (P-43m), (T{sub 4}R{sub 16})X{sub 20} (P4{sub 2}/nnm), (T{sub 4}R{sub 16})X{sub 24}(RX{sub 3}){sub 4} (I4{sub 1}/a) and (T{sub 4}R{sub 16})X{sub 23} (C2/m) types of structure) and pentamers ((Ru{sub 5}La{sub 14}){sub 2}Br{sub 39}, Cc) of (TR{sub r}){sub n} (n=2–5) clusters. These oligomers are further enveloped by inner (X{sup i}) as well as outer (X{sup a}) halido ligands, which possess diverse functionalities and interconnect like oligomers through i–i, i–a and/or a–i bridges. The general features of the crystal structures for these new compounds are discussed and compared to literature entries as well as different structure types with oligomeric T centered R clusters. Dimers and tetramers originating from the aggregation of (TR{sub 6}) octahedra via common edges are more frequent than trimers and pentamers, in which the (TR{sub r}) clusters share common faces. - Graphical abstract: Rare earth-metal cluster complexes with endohedral transition metal atoms (TR{sub 6}) may connect via common edges or faces to form dimers, trimers, tetramers and pentamers of which the tetramers are the most prolific. Packing effects and electron counts play an important role. - Highlights: • Rare-earth metal cluster complexes encapsulate transition metal atoms. • Oligomers are built via connection of octahedral clusters via common edges or faces. • Dimers through pentamers with closed structures are known. • Tetramers including a tetrahedron of endohedral atoms are the most prolific.

  15. Caracterización de nitratos alcalinos y alcalinoterreos por espectroscopia vibracional Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    OpenAIRE

    Martínez, S; Acción, F.; Puertas, F.

    1992-01-01

    [EN] Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide), employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1.387 cm~^ (present in the I.R. spectra of the four nitrates in KBr médium) allowed us to determine th...

  16. Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

    International Nuclear Information System (INIS)

    Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y1P←a1S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅ RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm−1). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr2 while this transition is quenched in Ba2. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba2 indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications

  17. Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie [Department of Chemistry, Maynooth University, National University of Ireland—Maynooth, County Kildare (Ireland)

    2016-01-28

    Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅ RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.

  18. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Science.gov (United States)

    Arévalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernández-Maldonado, Arturo J.

    2012-07-01

    The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium.

  19. Solubility of alkaline earth metal oxides in CsCl-KCl-NaCl eutectic mixture melt at 600 degC

    International Nuclear Information System (INIS)

    Products of solubility of alkaline-earth metal oxides in the melt of eutectic mixture CsCl-KCl-NaCl at 600 deg C were determined by the method of potentiometric titration. It is found that CaO and SrO under experimental conditions dissociate incompletely, while BaO is utterly dissociated: solubility of the oxides increases in the series MgO-CaO-SrO-BaO

  20. Syntheses and characterization of energetic compounds constructed from alkaline earth metal cations (Sr and Ba) and 1,2-bis(tetrazol-5-yl)ethane

    International Nuclear Information System (INIS)

    Two new energetic compounds, [M(BTE)(H2O)5]n (M=Sr(1), Ba(2)) [H2BTE=1,2-bis(tetrazol-5-yl)ethane], have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that they are isomorphous and exhibit 2D (4,4) net framework, generated by 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs linked up by two independent binding modes of H2BTE, and the resulting 2D structure is interconnected by hydrogen-bond and strong face to face π-π stacking interactions between two tetrazole rings to lead to a 3D supramolecular architecture. DSC measurements show that they have significant catalytic effects on thermal decomposition of ammonium perchlorate. Moreover, the photoluminescence properties, thermogravimetric analyses, and flame colors of the as-prepared compounds are also investigated in this paper. - Graphical abstract: Two novel 2D isomorphous alkaline earth metal complexes were assembled by 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs and two independent binding modes of H2BTE ligands, and the catalytic performances toward thermal decomposition of ammonium perchlorate and photoluminescent properties of them were investigated. Highlights: → Two novel alkaline earth energetic coordination polymers have been prepared.→ Both structures are layered based on 4-connected Sr2(H2O)10/Ba2(H2O)10 SBUs and two distinct H2BTE coordination modes.→ The dehydrated products of the compounds possess good thermostability and significant catalytic effects on thermal decomposition of AP.

  1. pH coupled co-precipitation of alkaline-earth carbonates and silica - complex materials from simple chemistry

    OpenAIRE

    Eiblmeier, Josef

    2013-01-01

    The present work deals with the mineralization of alkaline-earth carbonates (mainly barium carbonate) from dilute silica solutions at high pH. It has for long been known that the concerted interaction between these purely inorganic components leads to amazing architectures with intricately curved and helical shapes, which were termed silica-carbonate biomorphs. Recently a general concept was proposed by García-Ruiz and co-workers that explains the spontaneous formation of these biomimetic agg...

  2. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

    International Nuclear Information System (INIS)

    Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application

  3. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

    Directory of Open Access Journals (Sweden)

    X. D. Li

    2015-05-01

    Full Text Available Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

  4. Alkaline earth organometallic compounds in homogeneous catalysis : Synthesis, characterization and catalytic activity of calcium and magnesium complexes

    NARCIS (Netherlands)

    Penafiel, Johanne

    2016-01-01

    Homogeneous catalysis has been developed mainly through the use of transition metal complexes. However, transition-metal catalysts, often highly toxic, are becoming increasingly rare and consequently more expensive. Therefore, the search for sustainable alternatives is nowadays of great importance.

  5. Structures and Spectroscopy Studies of Two M(II-Phosphonate Coordination Polymers Based on Alkaline Earth Metals (M = Ba, Mg

    Directory of Open Access Journals (Sweden)

    Kui-Rong Ma

    2013-01-01

    Full Text Available The two examples of alkaline-earth M(II-phosphonate coordination polymers, [Ba2(L(H2O9]·3H2O (1 and [Mg1.5(H2O9]·(L-H21.5·6H2O (2 (H4L = H2O3PCH2N(C4H8NCH2PO3H2, N,N′-piperazinebis(methylenephosphonic acid, (L-H2 = O3PH2CHN(C4H8NHCH2PO3 have been hydrothermally synthesized and characterized by elemental analysis, FT-IR, PXRD, TG-DSC, and single-crystal X-ray diffraction. Compound 1 possesses a 2D inorganic-organic alternate arrangement layer structure built from 1D inorganic chains through the piperazine bridge, in which the ligand L−4 shows two types of coordination modes reported rarely at the same time. In 1, both crystallographic distinct Ba(1 and Ba(2 ions adopt 8-coordination two caps and 9-coordination three caps triangular prism geometry structures, respectively. Compound 2 possesses a zero-dimensional mononuclear structure with two crystallographic distinct Mg(II ions. Free metal cations   [MgO6]n2+ and uncoordinated anions (L-H2n2- are joined together by static electric force. Results of photoluminescent measurement indicate three main emission bands centered at 300 nm, 378.5 nm, and 433 nm for 1 and 302 nm, 378 nm, and 434.5 nm for 2 (λex=235 nm, respectively. The high energy emissions could be derived from the intraligand π∗-n transition stations of H4L (310 nm and 382 nm, λex=235 nm, while the low energy emission (>400 nm of 1-2 may be due to the coordination effect with metal(II ions.

  6. Comparisons between adsorption and diffusion of alkali, alkaline earth metal atoms on silicene and those on silicane: Insight from first-principles calculations

    Science.gov (United States)

    Bo, Xu; Huan-Sheng, Lu; Bo, Liu; Gang, Liu; Mu-Sheng, Wu; Chuying, Ouyang

    2016-06-01

    The adsorption and diffusion behaviors of alkali and alkaline-earth metal atoms on silicane and silicene are both investigated by using a first-principles method within the frame of density functional theory. Silicane is staler against the metal adatoms than silicene. Hydrogenation makes the adsorption energies of various metal atoms considered in our calculations on silicane significantly lower than those on silicene. Similar diffusion energy barriers of alkali metal atoms on silicane and silicene could be observed. However, the diffusion energy barriers of alkali-earth metal atoms on silicane are essentially lower than those on silicene due to the small structural distortion and weak interaction between metal atoms and silicane substrate. Combining the adsorption energy with the diffusion energy barriers, it is found that the clustering would occur when depositing metal atoms on perfect hydrogenated silicene with relative high coverage. In order to avoid forming a metal cluster, we need to remove the hydrogen atoms from the silicane substrate to achieve the defective silicane. Our results are helpful for understanding the interaction between metal atoms and silicene-based two-dimensional materials. Project supported by the Natural Science Foundation of Jiangxi Province, China (Grant Nos. 20152ACB21014, 20151BAB202006, and 20142BAB212002) and the Fund from the Jiangxi Provincial Educational Committee, China (Grant No. GJJ14254). Bo Xu is also supported by the Oversea Returned Project from the Ministry of Education, China.

  7. Interaction of alkali and alkaline earth ions with Ochratoxin A

    Energy Technology Data Exchange (ETDEWEB)

    Poor, Miklos [Institute of Laboratory Medicine, University of Pecs, Pecs H-7624 (Hungary); Kunsagi-Mate, Sandor; Matisz, Gergely; Li, Yin; Czibulya, Zsuzsanna [Department of General and Physical Chemistry, University of Pecs, Pecs H-7624 (Hungary); Janos Szentagothai Research Center, Pecs H-7624 (Hungary); Peles-Lemli, Beata [Department of General and Physical Chemistry, University of Pecs, Pecs H-7624 (Hungary); Koszegi, Tamas, E-mail: koszegit@freemail.hu [Institute of Laboratory Medicine, University of Pecs, Pecs H-7624 (Hungary)

    2013-03-15

    The effect of alkali and alkaline earth ions on the chemical equilibrium of mono- and dianionic forms of the mycotoxin Ochratoxin A (OTA) and their bonding onto the surface of Bovine Serum Albumin (BSA) have been investigated by fluorescence spectroscopy and fluorescence polarization techniques. Our results show that alkali metal ions shift the chemical equilibrium towards formation of dianionic form of OTA. Furthermore, the alkaline earth ions can compete with BSA for binding to OTA when these ions are present in millimolar concentrations. Our data also highlight the possibility that the 'free' fraction of OTA (not bound onto the surface of albumin) or at least a part of it is present in cation-bound form in body fluids. These observations are supported by stability constants and quantum-chemical calculations. Among the studied alkaline metal ions magnesium showed the highest affinity towards OTA under physiological conditions. Further research is required to analyze the potential significance of Mg{sup 2+}-OTA complex in cellular uptake and/or elimination of the toxin in the human body. - Highlights: Black-Right-Pointing-Pointer Fluorescence spectroscopy reveals cation-Ochratoxin A (OTA) interactions. Black-Right-Pointing-Pointer Alkali ions shift the equilibrium of OTA to formation of a dianionic structure. Black-Right-Pointing-Pointer Alkaline earth ions directly bind to OTA in the order: Mg{sup 2+}, Ca{sup 2+}, Ba{sup 2+}. Black-Right-Pointing-Pointer Quantum chemical calculations and logK values support our experimental data.

  8. Dipole Polarizability of Alkali-Metal (Na, K, Rb) - Alkaline-Earth-Metal (Ca,Sr) Polar molecules - Prospects of Alignment

    CERN Document Server

    Gopakumar, Geetha; Hada, Masahiko; Kajita, Masatoshi

    2014-01-01

    Electronic open-shell ground-state properties of selected alkali-metal (AM) - alkaline-earth-metal (AEM) polar molecules are investigated. We determine potential energy curves of the 2{\\Sigma}+ ground state at the coupled-cluster singles and doubles with partial triples (CCSD(T)) level of electron correlation. Calculated spectroscopic constants for the isotopes (23Na, 39K, 85Rb) - (40Ca, 88Sr) are compared with available theoretical and experimental results. The variation of the permanent dipole moment (PDM), average dipole polarizability, and polarizability anisotropy with internuclear distance is determined using finite-field perturbation theory at the CCSD(T) level. Owing to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u., RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for alignment and orientation in combined intense laser and external static electric fields.

  9. Ab initio properties of the ground-state polar and paramagnetic europium-alkali-metal-atom and europium-alkaline-earth-metal-atom molecules

    CERN Document Server

    Tomza, Michał

    2014-01-01

    The properties of the electronic ground state of the polar and paramagnetic europium-$S$-state-atom molecules have been investigated. Ab initio techniques have been applied to compute the potential energy curves for the europium-alkali-metal-atom, Eu$X$ ($X$=Li, Na, K, Rb, Cs), europium-alkaline-earth-metal-atom, Eu$Y$ ($Y$=Be, Mg, Ca, Sr, Ba), and europium-ytterbium, EuYb, molecules in the Born-Oppenheimer approximation for the high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within the small-core energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large internuclear distances $C_6$ are also reported. The EuK, EuRb, and EuCs molecules are examples of species poss...

  10. 2D and 3D alkaline earth metal carboxyphosphonate hybrids: Anti-corrosion coatings for metal surfaces

    International Nuclear Information System (INIS)

    Reactions of Mg2+ (1), Ca2+ (2), Sr2+ (3), or Ba2+ (4) salts with hydroxyphosphonoacetic acid (HPAA) at a 1:1 ratio yield M-HPAA layered coordination polymers. The crystal structures of 3 (two phases) and 4 have been determined by single crystal X-ray crystallography. Both stereoisomers (R and S) of HPAA are incorporated in the metal-HPAA materials. Synergistic combinations of Sr2+ or Ba2+ and HPAA at pH 7.3 are effective corrosion inhibitors for carbon steel, but are ineffective at pH 2.0. - Graphical abstract: Syntheses, characterization and crystal structures of metal-hydroxyphosphonoacetate hybrids are reported (Metal=Sr, Ba). 2D and 3D materials were prepared. Their anti-corrosion effects were studied at pH 2.0 and 7.3. It was found that anti-corrosion efficiency was demonstrated only at pH 7.3

  11. Enhanced Electroresponse of Alkaline Earth Metal-Doped Silica/Titania Spheres by Synergetic Effect of Dispersion Stability and Dielectric Property.

    Science.gov (United States)

    Yoon, Chang-Min; Lee, Seungae; Cheong, Oug Jae; Jang, Jyongsik

    2015-09-01

    A series of alkaline earth metal-doped hollow SiO2/TiO2 spheres (EM-HST) are prepared as electrorheological (ER) materials via sonication-mediated etching method with various alkaline earth metal hydroxides as the etchant. The EM-HST spheres are assessed to determine how their hollow interior and metal-doping affects the ER activity. Both the dispersion stability and the dielectric properties of these materials are greatly enhanced by the proposed one-step etching method, which results in significant enhancement of ER activity. These improvements are attributed to increased particle mobility and interfacial polarization originating from the hollow nature of the EM-HST spheres and the effects of EM metal-doping. In particular, Ca-HST-based ER fluid exhibits ER performance which is 7.1-fold and 3.1-fold higher than those of nonhollow core/shell silica/titania (CS/ST) and undoped hollow silica/titania (HST)-based ER fluids, respectively. This study develops a versatile and simple approach to enhancing ER activity through synergetic effects arising from the combination of dispersion stability and the unique dielectric properties of hollow EM-HST spheres. In addition, the multigram scale production described in this experiment can be an excellent advantage for practical and commercial ER application. PMID:26266695

  12. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V.; Goddard, William A., III

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

  13. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V; Goddard, William A

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems. PMID:27001855

  14. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    International Nuclear Information System (INIS)

    The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO2 adsorption performance. Highlights: ► Location of extraframework Sr2+ or Ba2+ cations was estimated by means of 1H and 23Na MAS NMR. ► Level of Sr2+ or Ba2+ ion exchange was limited by the presence of protons and sodium cations. ► Presence of ammonium cations in the supercages facilitated the exchange. ► Sr2+ and Ba2+ ion exchanged SAPOs are outstanding CO2 adsorbents.

  15. Two-band superfluidity and intrinsic Josephson effect in alkaline-earth-metal Fermi gases across an orbital Feshbach resonance

    Science.gov (United States)

    Iskin, M.

    2016-07-01

    We first show that the many-body Hamiltonian governing the physical properties of an alkaline-earth 173Yb Fermi gas across the recently realized orbital Feshbach resonance is exactly analogous to that of two-band s -wave superconductors with contact interactions; i.e., even though the free-particle bands have a tunable energy offset in between and are coupled by a Josephson-type attractive interband pair scattering, the intraband interactions have exactly the same strength. We then introduce two intraband order parameters within the BCS mean-field approximation and investigate the competition between their in-phase and out-of-phase (i.e., the so-called π -phase) solutions in the entire BCS-BEC evolution at zero temperature.

  16. Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)) Derived from Molecular Precursors and Doped with Eu(3+) Ions.

    Science.gov (United States)

    Drąg-Jarząbek, Anna; John, Łukasz; Petrus, Rafał; Kosińska-Klähn, Magdalena; Sobota, Piotr

    2016-03-24

    The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high-purity binary metal oxide perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)). Single-source molecular precursors [Ba4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2(η(2) -HOR)2 (HOR)2 Cl4], [Sr4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2 (HOR)4 Cl4], [Ca4 Zr2 (μ6-O)(μ3 ,η(2)-OR)8 (OR)2 Cl4], and [Ca6 Zr2 (μ2 ,η(2)-OR)12 (μ-Cl)2 (η(2) -HOR)4 Cl6 ]⋅8 CH2 Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2 ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2 CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray diffraction. The compounds were then thermally decomposed to MCl2 /MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskite-like oxide particles of 40-80 nm in size. Luminescence studies on Eu(3+)-doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology. PMID:26891039

  17. Quantum mechanics and molecular dynamics simulations of complexation of alkaline-earth and lanthanide cations by poly-amino-carboxylate ligands

    International Nuclear Information System (INIS)

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA4-, ethylene-diamino-tri-acetate-acetic acid EDTA(H)3-, tetra-aza-cyclo-dodecane-tetra-acetate DOTA4-, methylene-imidine-acetate MIDA2-) are reported. First, a consistent set of Lennard-Jones parameters for La3+, Eu3+ and Lu3+ cations has been derived from free energy calculations in aqueous solution. Observed differences in hydration free energies, coordination distances and hydration numbers are reproduced. Then, the solution structures of 1:1 complexes of alkaline-earth and/or lanthanide cations with EDTA4-, EDTA(H)3-, DOTA4- and 1:2 complexes of lanthanide cations with MIDA2- were studied by MD in water. In addition, free energy calculations were performed to study, for each ligand, the relative thermodynamic stabilities of complexes with Ca2+ vs Sr2+ and vs Ba2+ on the one hand, and with La3+ vs Eu3+ and vs Lu3+ on the other hand. Model does not take into account explicitly polarization and charge transfer. However, the results qualitatively agree with experimental complexation data (structure and selectivities). (author)

  18. Transient compounds of high alkaline earth metals with custom-made organic ligands as potential precursors for the gas phase separator of high temperature ceramic superconductors

    International Nuclear Information System (INIS)

    The aim of this work was the representation of new transient custom-made metal/organic compounds of the high alkaline earth metals Ca, Sr and Ba as potential precursors for the gas phase separation (chemical vapour deposition, CVD) of high temperature ceramic superconductors. There is a report on the synthesis and comprehensive characterisation of representatives of the class of compounds of substituted metallocenes and the B diketone compounds of these metals. Some selected compounds were examined as regards their suitability for CVD. The main task was the examination of the effect of structural and electronic parameters of ligands on the properties of the compounds, where the volatility was to the fore. (orig./MM)

  19. Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N-(2-Pyridylethyl)-N'-(2,6-diisopropylphenyl)pivalamidine.

    Science.gov (United States)

    Kalden, Diana; Oberheide, Ansgar; Loh, Claas; Görls, Helmar; Krieck, Sven; Westerhausen, Matthias

    2016-07-25

    N-(2,6-Diisopropylphenyl)-N'-(2-pyridylethyl)pivalamidine (Dipp-N=C(tBu)-N(H)-C2 H4 -Py) (1), reacts with metalation reagents of lithium, magnesium, calcium, and strontium to give the corresponding pivalamidinates [(tmeda)Li{Dipp-N=C(tBu)-N-C2 H4 -Py}] (6), [Mg{Dipp-N=C(tBu)-N-C2 H4 -Py}2 ] (3), and heteroleptic [{(Me3 Si)2 N}Ae{Dipp-N=C(tBu)-N-C2 H4 -Py}], with Ae being Ca (2 a) and Sr (2 b). In contrast to this straightforward deprotonation of the amidine units, the reaction of 1 with the bis(trimethylsilyl)amides of sodium or potassium unexpectedly leads to a β-metalation and an immediate deamidation reaction yielding [(thf)2 Na{Dipp-N=C(tBu)-N(H)}] (4 a) or [(thf)2 K{Dipp-N=C(tBu)-N(H)}] (4 b), respectively, as well as 2-vinylpyridine in both cases. The lithium derivative shows a similar reaction behavior to the alkaline earth metal congeners, underlining the diagonal relationship in the periodic table. Protonation of 4 a or the metathesis reaction of 4 b with CaI2 in tetrahydrofuran yields N-(2,6-diisopropylphenyl)pivalamidine (Dipp-N=C(tBu)-NH2 ) (5), or [(thf)4 Ca{Dipp-N=C(tBu)-N(H)}2 ] (7), respectively. The reaction of AN(SiMe3 )2 (A=Na, K) with less bulky formamidine Dipp-N=C(H)-N(H)-C2 H4 -Py (8) leads to deprotonation of the amidine functionality, and [(thf)Na{Dipp-N=C(H)-N-C2 H4 -Py}]2 (9 a) or [(thf)K{Dipp-N=C(H)-N-C2 H4 -Py}]2 (9 b), respectively, are isolated as dinuclear complexes. From these experiments it is obvious, that β-metalation/deamidation of N-(2-pyridylethyl)amidines requires bases with soft metal ions and also steric pressure. The isomeric forms of all compounds are verified by single-crystal X-ray structure analysis and are maintained in solution. PMID:27355970

  20. Bacterial Degradation of Cyanide and Its Metal Complexes under Alkaline Conditions

    OpenAIRE

    Luque-Almagro, Víctor M.; Huertas, María-J.; Martínez-Luque, Manuel; Moreno-Vivián, Conrado; Roldán, M. Dolores; García-Gil, L. Jesús; Castillo, Francisco; Blasco, Rafael

    2005-01-01

    A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Colección Española de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) ...

  1. Production of Synthesis Gas via Methane Reforming with CO2 on Ni/SiO2 Catalysts Promoted by Alkali and Alkaline Earth Metals

    Institute of Scientific and Technical Information of China (English)

    陈平; 侯昭胤; 郑小明

    2005-01-01

    Ni/SiO2 catalysts promoted by alkali metals K and Cs or alkaline earth metals Mg, Ca, Sr and Ba were prepared, characterized by H2-TPR and XRD, and used for the production of synthesis gas via methane reforming with CO2. Though K and Cs promoted Ni catalysts could eliminate coke deposition, the reforming activity of these promoted catalysts was decreased heavily. Mg and Ca promoted Ni/SiO2 catalysts exhibited excellent coke resistance ability with minor loss of the reforming activity of Ni/SiO2. Ba showed poor coke resistance ability and small amount of Sr increased the formation of coke. The possible mechanism of these promoters was discussed.

  2. Additive effects of alkaline-earth metals and nickel on the performance of Co/γ-Al2O3 in methane catalytic partial oxidation

    Institute of Scientific and Technical Information of China (English)

    Changlin Yu; Weizheng Weng; Qing Shu; Xiangjie Meng; Bin Zhang; Xirong Chen; Xiaochun Zhou

    2011-01-01

    Nano-sized γ-alumina(γ-Al2O3)was first prepared by a precipitation method.Then,active component of cobalt and a series of alkalineearth metal promoters or nickel(Ni)with different contents were loaded on the γ-Al2O3 support.The catalysts were characterized by N2 adsorption-desorption,X-ray diffraction(XRD)and thermogravimetry analysis(TGA).The activity and selectivity of the catalysts in catalytic partial oxidation(CPO)of methane have been compared with Co/γ-Al2O3,and it is found that the catalytic activity,selectivity,and stability are enhanced by the addition of alkaline-earth metals and nickel.The optimal loadings of strontium(Sr)and Ni were 6 and 4 wt%,respectively.This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane.

  3. Dark-state suppression and optimization of laser cooling and fluorescence in a trapped alkaline-earth-metal single ion

    CERN Document Server

    Lindvall, T; Tittonen, I; Madej, A A; 10.1103/PhysRevA.86.033403

    2012-01-01

    We study the formation and destabilization of dark states in a single trapped 88Sr+ ion caused by the cooling and repumping laser fields required for Doppler cooling and fluorescence detection of the ion. By numerically solving the time-dependent density matrix equations for the eight-level system consisting of the sublevels of the 5s 2S1/2, 5p 2P1/2, and 4d 2D3/2 states, we analyze the different types of dark states and how to prevent them in order to maximize the scattering rate, which is crucial for both the cooling and the detection of the ion. The influence of the laser linewidths and ion motion on the scattering rate and the dark resonances is studied. The calculations are then compared with experimental results obtained with an endcap ion trap system located at the National Research Council of Canada and found to be in good agreement. The results are applicable also to other alkaline earth ions and isotopes without hyperfine structure.

  4. Rare earth elements and titanium in plants, soils and groundwaters in the alkaline-ultramafic complex of Salitre, MG, Brazil

    OpenAIRE

    Ceccantini, G.; Figueiro, A.M.G.; Sondag, Francis; Soubiès, François

    1997-01-01

    The contents of Rare Earth Elements (REE) and titanium in various species of plants, in groundwaters and in soils from the ultramafic complex of Salitre, MG, Brazil, were determined. Due to the particular mineralogy of the bedrock, REE and Ti present high concentrations in the soils. The transfer factors of the REE from soil to plants were calculated, giving values ranging from 0.0001 to 0.0028, much lower than the values reported elsewhere in Brazil. Furthermore, as suggested by other author...

  5. Rare-earth metal π-complexes of reduced arenes, alkenes, and alkynes: Bonding, electronic structure, and comparison with actinides and other electropositive metals

    OpenAIRE

    Huang, W.; Diaconescu, PL

    2015-01-01

    © 2015 The Royal Society of Chemistry. Rare-earth metal complexes of reduced π ligands are reviewed with an emphasis on their electronic structure and bonding interactions. This perspective discusses reduced carbocyclic and acyclic π ligands; in certain categories, when no example of a rare-earth metal complex is available, a closely related actinide analogue is discussed. In general, rare-earth metals have a lower tendency to form covalent interactions with π ligands compared to actinides, m...

  6. Metallic complexes with glyphosate: a review

    International Nuclear Information System (INIS)

    We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature. (author)

  7. Alkaline earths as main group reagents in molecular catalysis.

    Science.gov (United States)

    Hill, Michael S; Liptrot, David J; Weetman, Catherine

    2016-02-21

    The past decade has witnessed some remarkable advances in our appreciation of the structural and reaction chemistry of the heavier alkaline earth (Ae = Mg, Ca, Sr, Ba) elements. Derived from complexes of these metals in their immutable +2 oxidation state, a broad and widely applicable catalytic chemistry has also emerged, driven by considerations of cost and inherent low toxicity. The considerable adjustments incurred to ionic radius and resultant cation charge density also provide reactivity with significant mechanistic and kinetic variability as group 2 is descended. In an attempt to place these advances in the broader context of contemporary main group element chemistry, this review focusses on the developing state of the art in both multiple bond heterofunctionalisation and cross coupling catalysis. We review specific advances in alkene and alkyne hydroamination and hydrophosphination catalysis and related extensions of this reactivity that allow the synthesis of a wide variety of acyclic and heterocyclic small molecules. The use of heavier alkaline earth hydride derivatives as pre-catalysts and intermediates in multiple bond hydrogenation, hydrosilylation and hydroboration is also described along with the emergence of these and related reagents in a variety of dehydrocoupling processes that allow that facile catalytic construction of Si-C, Si-N and B-N bonds. PMID:26797470

  8. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    Science.gov (United States)

    Singh, David Joseph

    2013-07-16

    A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

  9. Long range interactions between alkali and alkaline-earth atoms

    CERN Document Server

    Jiang, Jun; Mitroy, J

    2013-01-01

    Dispersion coefficients between the alkali metal atoms (Li-Rb) and alkaline-earth metal atoms (Be-Sr) are evaluated using matrix elements computed from frozen core configuration interaction calculations. Besides dispersion coefficients with both atoms in their respective ground states, dispersion coefficients are also given for the case where one atom is in its ground state and the other atom is in a low lying excited state.

  10. Separation of stable isotopes of alkali and alkaline earth metals in chemical exchange systems with crown ethers

    International Nuclear Information System (INIS)

    Chemical isotope exchange in two-phase water - organic systems Men+ (water) - MeLn+ (org), where Me = Li, Ca, K, Mg; L = crown ethers with 5 to 6 oxygen atoms in macrocyclic ring; org = CHCl3, CH2Cl2 has been studied. The process of isotope separation has been realized by extraction chromatography. The chromatographic column contained a fixed aqueous phase. The organic solution of metal complex with crown ether was eluted through the column. On contact with the fixed aqueous phase in the course of chromatography, metal salt reextraction occurred and interphase isotope exchange between aqueous and organic phases resulted. Isotope separation factors in these systems were in the range of: 1.0032 - 1.020 (6Li/7Li), 1.0016 - 1.0038 (40Ca/44Ca), 1.0007 - 1.0011 (39K/41K), 1.0014 - 1.0044 (24Mg/26Mg). The theoretical model has been proposed to interpret the high separation factors in crown ether extraction systems. According to this model, the potential in such systems has a very flat bottom. This type of potential results in weakening the force field and decreasing of β-factor (i.e., (s/s')f) in spite of comparatively high energy of complexation. This model can interpret both high separation factors and their strong dependence on the type of crown ether. (author)

  11. Enhanced NH{sub 3} gas sensing performance based on electrospun alkaline-earth metals composited SnO{sub 2} nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shuang [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Kan, Kan [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Daqing Branch, Heilongjiang Academy of Sciences, Daqing 163319 (China); Yang, Ying; Jiang, Chao [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Gao, Jun [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Department of Chemistry, Harbin Normal University, Harbin 150025 (China); Jing, Liqiang [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Shen, Peikang [Department of Physics and Engineering Sun Yat-sen University, Guangzhou 510275 (China); Li, Li, E-mail: llwjjhlju@sina.cn [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); and others

    2015-01-05

    Highlights: • The small-sized SnO{sub 2} (5–7 nm) were obtained by adding the alkaline-earth. • Sr-composited SnO{sub 2} nanofibers showed uniform nanotubes structure (Sr/SnO{sub 2}). • Sr/SnO{sub 2} showed an excellent sensing performance to NH{sub 3} at room temperature. - Abstract: One-dimensional alkaline-earth metals composited SnO{sub 2} (Ae/SnO{sub 2}) nanofibres were fabricated via electrospinning technique, followed by thermal treatment at 600 °C for 5 h. Transmission electron microscopy (TEM) studies showed that the nanoparticles size of Ae/SnO{sub 2} was 5–7 nm, which was smaller than the pristine SnO{sub 2} nanorods attached by 20 nm nanoparticles. Moreover, Sr/SnO{sub 2} nanocomposites showed uniform nanotubes structure with the wall thickness of about 30 nm, in which all the nanoparticles were connected to their neighbors by necks. The Sr/SnO{sub 2} nanotubes exhibited an excellent sensing response toward NH{sub 3} gas at room temperature, lower detection limit (10 ppm), faster response time (6 s towards 2000 ppm∼16 s towards 10 ppm) and better reversibility compared to the pristine SnO{sub 2} nanorods. The enhanced sensor performances were attributed to the higher conductivity of the Sr/SnO{sub 2}. Mott–Schottky plots (M–S) and electrochemical impedance spectroscopy (EIS) measurements indicated that the carrier density of Sr/SnO{sub 2} nanotubes was 3 fold of that pristine SnO{sub 2}.

  12. Use of the ion exchange method for the determination of stability constants of trivalent metal complexes with humic and fulvic acids II. Tb3+, Yb3+ and Gd3+ complexes in weakly alkaline conditions

    International Nuclear Information System (INIS)

    The conditional stability constants for tracer concentrations of Tb(III), Yb(III), and Gd(III) with three soil humic acids, three soil fulvic acids and a fulvic acid from weathered coal were determined at pH 9.0-9.1 (these values are similar to those in calcareous soils) in the presence of NaHCO3 by using the anion exchange method. It was found that 1 : 1 and 1 : 2 complexes were simultaneously formed in the weakly alkaline conditions. The conditional stability constants of these 1 : 1 and 1 : 2 complexes were calculated from the distribution coefficients of rare earth elements at various concentrations of humate or fulvate. The stability constants indicate the very high stability of trivalent Tb3+, Yb3+ and Gd3+ complexes with humic substances in weakly alkaline conditions. The key parameters necessary for the experimental determination of the conditional stability constants of metal ions with humic substances in the presence of NaHCO3 by using an anion exchange method were discussed. The conditional stability constants of these 1 : 1 and 1 : 2 complexes were compared in this paper. It was found that stabilities of Tb3+ 1 : 1 and 1 : 2 complexes with humic acid are greater than the corresponding ones with fulvic acid from the same soil. In addition, the effect of the presence of Ca2+ as a competitor on the stabilities of 1 : 1 and 1 : 2 complexes of Yb was examined and no pronounced change of stabilities of 1 : 1 complex was found, even though Ca2+ is in a 103 excess to Yb3+

  13. Alkaline Earth Core Level Photoemission Spectroscopy of High-Temperature Superconductors

    Science.gov (United States)

    Vasquez, R.

    1993-01-01

    This paper examines photoemission measurements of the alkaline Earth core levels of high-temperature superconductors and related materials, models that seek to explain the large negative shifts observed relative to the corresponding alkaline Earth metals, and the effect of lattice site disorder on the core level spectra and the presence or absence of intrinsic surface peaks.

  14. Alkaline earth cation extraction from acid solution

    Science.gov (United States)

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  15. Co-mineralization of alkaline-earth carbonates and silica

    OpenAIRE

    Kellermeier, Matthias

    2011-01-01

    This thesis is concerned with the manifold interactions that occur when alkaline-earth metal carbonates are crystallized in the presence of dissolved silica as an additive. The described work subdivides into two main lines of research. On the one hand, an understanding of the potential roles of silica during crystallization was sought on a fundamental level. That is, the mineral - in this case calcium carbonate - was directly precipitated from silica-containing solutions and the effect on gro...

  16. Bis(imidazolin-2-iminato) rare earth metal complexes: synthesis, structural characterization, and catalytic application.

    Science.gov (United States)

    Trambitas, Alexandra G; Melcher, Daniel; Hartenstein, Larissa; Roesky, Peter W; Daniliuc, Constantin; Jones, Peter G; Tamm, Matthias

    2012-06-18

    Reaction of anhydrous rare earth metal halides MCl(3) with 2 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) and 2 equiv of trimethylsilylmethyl lithium (Me(3)SiCH(2)Li) in THF furnished the complexes [(Im(Dipp)N)(2)MCl(THF)(n)] (M = Sc, Y, Lu). The molecular structures of all three compounds were established by single-crystal X-ray diffraction analyses. The coordination spheres around the pentacoordinate metal atoms are best described as trigonal bipyramids. Reaction of YbI(2) with 2 equiv of LiCH(2)SiMe(3) and 2 equiv of the imino ligand Im(Dipp)NH in tetrahydrofuran did not result in a divalent complex, but instead the Yb(III) complex [(Im(Dipp)N)(2)YbI(THF)(2)] was obtained and structurally characterized. Treatment of [(Im(Dipp)N)(2)MCl(THF)(n)] with 1 equiv of LiCH(2)SiMe(3) resulted in the formation of [(Im(Dipp)N)(2)M(CH(2)SiMe(3))(THF)(n)]. The coordination arrangement of these compounds in the solid state at the metal atoms is similar to that found for the starting materials, although the introduction of the neosilyl ligand induces a significantly greater distortion from the ideal trigonal-bipyramidal geometry. [(Im(Dipp)N)(2)Y(CH(2)SiMe(3))(THF)(2)] was used as precatalyst in the intramolecular hydroamination/cyclization reaction of various terminal aminoalkenes and of one aminoalkyne. The complex showed high catalytic activity and selectivity. A comparison with the previously reported dialkyl yttrium complex [(Im(Dipp)N)Y(CH(2)SiMe(3))(2)(THF)(3)] showed no clear tendency in terms of activity. PMID:22662762

  17. CO{sub 2} Capture Properties of Alkaline-earth Metal Oxides and Hydroxides: A Combined Density Functional Theory and Lattice Phonon Dynamics Study

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Yuhua; Sorescu, Dan

    2010-01-01

    By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO{sub 2} absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH){sub 2} (where M = Be,Mg,Ca,Sr,Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO{sub 2} capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH){sub 2} systems were found to be better candidates for CO{sub 2} sorbent applications due to their lower operating temperatures (600–700 K). In the presence of H{sub 2}O, MgCO{sub 3} can be regenerated into Mg(OH){sub 2} at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO{sub 2} pressure but also on the H{sub 2}O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO{sub 2} sorbents.

  18. CO2 capture properties of alkaline earth metal oxides and hydroxides: A combined density functional theory and lattice phonon dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Yuhua [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Sorescu, Dan C. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2010-01-01

    By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO2 absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH)2 (where M = Be, Mg, Ca, Sr, Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO2 capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH)2 systems were found to be better candidates for CO2 sorbent applications due to their lower operating temperatures (600-700 K). In the presence of H2O, MgCO3 can be regenerated into Mg(OH)2 at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO2 pressure but also on the H2O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO2 sorbents.

  19. CO(2) capture properties of alkaline earth metal oxides and hydroxides: A combined density functional theory and lattice phonon dynamics study.

    Science.gov (United States)

    Duan, Yuhua; Sorescu, Dan C

    2010-08-21

    By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO(2) absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH)(2) (where M=Be,Mg,Ca,Sr,Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO(2) capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH)(2) systems were found to be better candidates for CO(2) sorbent applications due to their lower operating temperatures (600-700 K). In the presence of H(2)O, MgCO(3) can be regenerated into Mg(OH)(2) at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO(2) pressure but also on the H(2)O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO(2) sorbents. PMID:20726653

  20. Theoretical study for the reduction of N2O with CO Mediated by alkaline-earth metal oxide cations 2MO+(M=Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    The reaction mechanism of the reaction N2O(0Σ+) + CO (1Σ+)→N2 (1Σg+) + CO2 (1Σg+) mediated by alkaline-earth metal oxide cations 2MO+ (m=Ca, Sr, Ba) have been investigated by using the UB3LYP and CCSD (T) levels of theory. The O-atom affinities (OA) testified that only the 2CaO+ can capture O from N2O and transfer O to CO is thermodynamically allowed in three ions. The processes can be expressed as channels l and 2 for the reaction of N2O and CO mediated by 2MO+ (M=Ca, Sr, Ba). For the former, the main reaction processes in a two-step manner to products, the 2MO+, as a catalyzer, transports an oxygen atom from N2O to CO. For the latter, firstly, the N2O interact with the 2MO+ to form IM1, then IM1 interact with the CO to form IM2', along the reaction pathway the intermediate species convert into products 21MO+, N2 and CO2. From above results, the following conclusion was drawn. The channel 2 is kinetically and thermodynamically feasible. Our calculated results show the title reactions are accord with the experiment. (authors)

  1. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

    Full Text Available Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  2. Heterometallic Alkaline Earth-Lanthanide Ba(II)-La(III) Microporous Metal-Organic Framework as Bifunctional Luminescent Probes of Al(3+) and MnO4(.).

    Science.gov (United States)

    Ding, Bin; Liu, Shi Xin; Cheng, Yue; Guo, Chao; Wu, Xiang Xia; Guo, Jian Hua; Liu, Yuan Yuan; Li, Yan

    2016-05-01

    In this work a rigid asymmetrical tricarboxylate ligand p-terphenyl-3,4″,5-tricarboxylic acid (H3L) has been employed, and a unique heterometallic alkaline earth-lanthanide microporous luminescent metal-organic framework (MOF) {[Ba3La0.5(μ3-L)2.5(H2O)3(DMF)]·(3DMF)}n (1·3DMF) (DMF = dimethylformamide) has been isolated under solvothermal conditions. Single-crystal X-ray structural analysis demonstrates that 2D inorganic Ba-O-La connectivity can be observed in 1, which are further bridged via rigid terphenyl backbones of L(3-), forming a unique I(2)O(1)-type microporous luminescent framework. A 1D microporous channel with dimensionality of 9.151(3) Å × 10.098(1) Å can be observed along the crystallographic a axis. PXRD patterns have been investigated indicating pure phases of 1. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive sensing for Al(3+) over other cations with high quenching efficiency Ksv value of 1.445 × 10(4) L·mol(-1) and low detection limit (1.11 μM (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive sensing for MnO4(-) over other anions with quenching efficiency Ksv = 7.73 × 10(3) L·mol(-1) and low detection limit (0.28 μM (S/N = 3)). It is noted that, when different concentrations of MnO4(-) solutions (0.5 to 100 μM) were dropped into the suspension of 1, the bright blue luminescence of the suspension observed under UV light can gradually change into pink color, indicating visually luminescent sensing, which makes the detection process of MnO4(-) more convenient in practical. The result also reveals that 1 represents the first example of bifunctional heterometallic alkaline earth-lanthanide MOF-based luminescent probes for selectively detecting Al(3+) and MnO4(-) in the water solutions. PMID:27088966

  3. Complexes of earth-abundant metals for catalytic electrochemical hydrogen generation under aqueous conditions.

    Science.gov (United States)

    Thoi, V Sara; Sun, Yujie; Long, Jeffrey R; Chang, Christopher J

    2013-03-21

    Growing global energy demands and climate change motivate the development of new renewable energy technologies. In this context, water splitting using sustainable energy sources has emerged as an attractive process for carbon-neutral fuel cycles. A key scientific challenge to achieving this overall goal is the invention of new catalysts for the reductive and oxidative conversions of water to hydrogen and oxygen, respectively. This review article will highlight progress in molecular electrochemical approaches for catalytic reduction of protons to hydrogen, focusing on complexes of earth-abundant metals that can function in pure aqueous or mixed aqueous-organic media. The use of water as a reaction medium has dual benefits of maintaining high substrate concentration as well as minimizing the environmental impact from organic additives and by-products. PMID:23034627

  4. Reduction Chemistry of Rare-Earth Metal Complexes: Toward New Reactivity and Properties

    OpenAIRE

    Huang, Wenliang

    2013-01-01

    Rare-earths are a group of metals with fascinating physical properties and intriguing chemical reactivity. Organometallic rare-earth chemistry is of particular interest because of the increasing number of their applications in industry and consumer goods as well as the importance of understanding their physical and chemical properties. Despite the dominance of the trivalent oxidation state, recently, low-valent organometallic rare-earth compounds were characterized and showed interesting reac...

  5. Retention of alkaline earth elements in man

    International Nuclear Information System (INIS)

    The data on human metabolism and long-term retention of alkaline earth elements (133Ba injected into six healthy male volunteers at age 25-81 y and 45Ca and 85Sr received by one healthy male volunteer) are presented. Excreta were collected for 2-3 weeks after injection of the tracer into an antecubital vein. Activity in urine, ashed faeces and early samples of blood plasma was determined by gamma-ray scintillation spectrometry. Whole body retention has been assessed through serial measurements of body radioactivity. The injected 133Ba apparently became mainly skeletal within several days, much earlier than predicted by the ICRP model. The whole-body retention at 32 d ranged from 5 to 14%, the rate of loss correlating with the excretory plasma clearance rate. No age-related trends were identified in the metabolism of Ca and Sr. 2 refs, 2 figs

  6. New Alkaline-Earth Polymeric Frameworks as green materials for sorption and heterogeneous catalysis

    OpenAIRE

    Platero Prats, Ana Eva

    2011-01-01

    Metal-Organic Frameworks (or MOFs) are porous organic-inorganic crystalline materials in which the metallic centers are joined through organic ligands via coordination bonds to give frameworks with different dimensionalities. The work presented in this thesis is focused on the obtaining of new MOFs using alkaline-earth elements as metal centers, which could represent a comparatively cheap, nontoxic and green alternative to conventional MOFs based on transition metals or rare-earth elements.Th...

  7. Proposal for Laser Cooling of Alkaline Earth Monoalkoxide Free Radicals

    Science.gov (United States)

    Baum, Louis; Kozyryev, Ivan; Matsuda, Kyle; Doyle, John M.

    2016-05-01

    Cold samples of polyatomic molecules will open new avenues in physics, chemistry, and quantum science. Non-diagonal Franck-Condon factors, technically challenging wavelengths, and the lack of strong electronic transitions inhibit direct laser cooling of nonlinear molecules. We identify a scheme for optical cycling in certain molecules with six or more atoms. Replacing hydrogen in alcohols with an alkaline earth metal (M) leads to alkaline earth monoalkoxide free radicals (MOR), which have favorable properties for laser cooling. M-O bond is very ionic, so the metal orbitals are slightly affected by the nature of R on the ligand. Diagonal Franck-Condon factors, laser accessible transitions, and a small hyperfine structure make MOR molecules suitable for laser cooling. We explore a scheme for optical cycling on the A - X transition of SrOCH3 . Molecules lost to dark vibrational states will be repumped on the B - X transition. Extension to larger species is possible through expansion of the R group since transitions involve the promotion of the metal-centered nonbonding valence electron. We will detail our estimations of the Franck-Condon factors, simulations of the cooling process and describe progress towards the Doppler cooling of MOR polyatomics.

  8. Characterization and activity of alkaline earth metals loaded CeO{sub 2}–MO{sub x} (M = Mn, Fe) mixed oxides in catalytic reduction of NO

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Seyed Mahdi [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Niaei, Aligholi, E-mail: niaei@yahoo.com [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Illán Gómez, María José [Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, Universidad de Alicante, Alicante (Spain); Salari, Dariush; Nakhostin Panahi, Parvaneh [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Abaladejo-Fuentes, Vicente [Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, Universidad de Alicante, Alicante (Spain)

    2014-02-14

    Nanocrystalline CeO{sub 2}–MO{sub x} mixed oxides (M = Mn, Fe) with different M/(M + Ce) molar ratio are prepared by sol–gel combustion method. X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Temperature Programmed Reduction with H{sub 2} (H{sub 2}-TPR) and N{sub 2}-adsorption (BET) analyses are conducted to characterize the physical–chemical properties of the catalysts. The activity of catalysts for reduction of NOx with ammonia has been evaluated. The CeO{sub 2}–MnO{sub x} catalysts showed better low temperature activity than CeO{sub 2}–FeO{sub x}. The superior activity of CeO{sub 2}–MnO{sub x} with Mn/(Mn + Ce) molar ratio of 0.25 respect to other catalysts (with 83% NO conversion and 68% N{sub 2} yield at 200 °C) is associated to nanocrystalline structure, reducibility at low temperature and synergistic effect between Ce and Mn that are observed by XRD, TEM and H{sub 2}-TPR. The CeO{sub 2}–FeO{sub x} catalysts were found to be active at high temperature, being Ce–Fe the best catalyst yielded 82% NO conversion at 300 °C. The effect of alkaline earth metals (Ca, Mg, Sr and Ba) loading on the structure and catalytic activity of cerium mixed oxides are also investigated. Loading of Ba enhanced the NO reduction activity of mixed oxides due to the increase of number of basic sites. Highest performance with 91% NO conversion and 80% N{sub 2} yield attained over CeO{sub 2}–MnO{sub x} (0.25)-Ba (7%) catalyst at 200 °C. - Highlights: • CeO{sub 2}–MO{sub x} mixed oxides (M = Mn, Fe) were synthesized by sol–gel combustion method. • The activity of mixed oxides is evaluated in catalytic reduction of NO with NH{sub 3}. • The CeO{sub 2}–MnO{sub x} showed better activity than CeO{sub 2}–FeO{sub x} due to better redox properties. • Ba loading enhanced the activity due to the increase of number of basic sites. • 91% NO conversion and 80% N{sub 2} yield attained over 7%Ba–Ce{sub 0.75}Mn{sub 0.25}O{sub 2} at 200 °C.

  9. Study of sorption regularities of alkaline and alkali-earth metals cations by sorbents on the basis of zirconium amorphous phosphate

    International Nuclear Information System (INIS)

    In order to obtain the samples of zirconium phosphates in the form of spherical granulation the hydrogel granules of zirconium dioxides were treatment by aqueous solutions of orthophosphoric acid and dihydrophosphate of alkaline metals. Their ion exchange properties were studied by means of potentiometric titration method. The influence of thermal treatment on structural-sorption properties of ion exchangers was studied. It was defined that with temperature increasing of samples treatment their specific surface area decreases, the volume of sorption pores and sorption capacity decreases as well.

  10. {sup 1}H and {sup 23}Na MAS NMR spectroscopy of cationic species in CO{sub 2} selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Arevalo-Hidalgo, Ana G. [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico); Dugar, Sneha; Fu, Riqiang [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Hernandez-Maldonado, Arturo J., E-mail: arturoj.hernandez@upr.edu [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico)

    2012-07-15

    The location of extraframework cations in Sr{sup 2+} and Ba{sup 2+} ion-exchanged SAPO-34 was estimated by means of {sup 1}H and {sup 23}Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO{sub 2} adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO{sub 2} adsorption performance. Highlights: Black-Right-Pointing-Pointer Location of extraframework Sr{sup 2+} or Ba{sup 2+} cations was estimated by means of {sup 1}H and {sup 23}Na MAS NMR. Black-Right-Pointing-Pointer Level of Sr{sup 2+} or Ba{sup 2+} ion exchange was limited by the presence of protons and sodium cations. Black-Right-Pointing-Pointer Presence of ammonium cations in the supercages facilitated the exchange. Black-Right-Pointing-Pointer Sr{sup 2+} and Ba{sup 2+} ion exchanged SAPOs are outstanding CO{sub 2} adsorbents.

  11. Magic wavelengths in the alkaline earth ions

    CERN Document Server

    Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K

    2015-01-01

    We present magic wavelengths for the $nS$ - $nP_{1/2,3/2}$ and $nS$ - $mD_{3/2,5/2}$ transitions, with the respective ground and first excited $D$ states principal quantum numbers $n$ and $m$, in the Mg$^+$, Ca$^+$, Sr$^+$ and Ba$^+$ alkaline earth ions for linearly polarized lights by plotting dynamic polarizatbilities of the $nS$, $nP_{1/2,3/2}$ and $mD_{3/2,5/2}$ states of the ions. These dynamic polarizabilities are evaluated by employing a relativistic all-order perturbative method and their accuracies are ratified by comparing their static values with the available high precision experimental or other theoretical results. Moreover, some of the magic wavelengths identified by us in Ca$^+$ concurs with the recent measurements reported in [{\\bf Phys. Rev. Lett. 114, 223001 (2015)}]. Knowledge of these magic wavelengths are propitious to carry out many proposed high precision measurements trapping the above ions in the electric fields with the corresponding frequencies.

  12. Synthesis and infrared spectra of alkaline earth metal carbonates formed by the reaction of metal salts with urea at high temperature

    Indian Academy of Sciences (India)

    S M Teleb; D El-Sayed Nassr; E M Nour

    2004-12-01

    The metal carbonate, MCO3 (M = Ca, Sr and Ba), was synthesized by a novel method of reacting aqueous solution of each of Ca2+, Sr2+ and Ba2+ salts with urea at high temperature, ∼ 80°C. The reaction products were characterized through elemental analysis and infrared spectra. The infrared spectra of the products are the same as those of the corresponding commercially obtained carbonates. A general reaction describing the formation of MCO3 is proposed.

  13. STUDY ON POLYMER-RARE EARTH METAL ION COMPLEXES I. FLUORESCENT PROPERTIES OF POLY(ACRYLIC ACID-CO-4-VINYLPYRIDINE)-RARE EARTH METAL COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    LU Hong; FANG Shibi; JIANG Yingyan

    1987-01-01

    A kind of copolymer of acrylic acid and vinylpyridine was synthesized and the fluorescent properties of the complexes of the copolymer with Eu3+ or Tb3+ were studied. It was found that the fluorescence intensity of the complexes of the copolymer with Eu3+ was 20 times as high as that of the complexes of polyacrylic acid with Eu3+ and twice as high as that of the complexes of polyvinylpyridine with Eu3+. The effects of the composition of the copolymer and the content of Eu3+ or Tb3+ in the complexes were studied.The fluorescence lifetime of the complexes was measured and it was found that two or more kinds of energy transfer mechanism existed.

  14. Recent advances in Rydberg physics using alkaline-earth atoms

    Science.gov (United States)

    Dunning, F. B.; Killian, T. C.; Yoshida, S.; Burgdörfer, J.

    2016-06-01

    In this brief review, the opportunities that the alkaline-earth elements offer for studying new aspects of Rydberg physics are discussed. For example, the bosonic alkaline-earth isotopes have zero nuclear spin which eliminates many of the complexities present in alkali Rydberg atoms, permitting simpler and more direct comparison between theory and experiment. The presence of two valence electrons allows the production of singlet and triplet Rydberg states that can exhibit a variety of attractive or repulsive interactions. The availability of weak intercombination lines is advantageous for laser cooling and for applications such as Rydberg dressing. Excitation of one electron to a Rydberg state leaves behind an optically active core ion allowing, for high-L states, the optical imaging of Rydberg atoms and their (spatial) manipulation using light scattering. The second valence electron offers the possibility of engineering long-lived doubly excited states such as planetary atoms. Recent advances in both theory and experiment are highlighted together with a number of possible directions for the future.

  15. Determination of alkaline earth metal ions in solar salt by ion chromatography after solvent extraction with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

    International Nuclear Information System (INIS)

    Ion chromatography was effectively applied to the determination of alkaline earth elements (Mg, Ca, Sr and Ba) in solar salt after extraction with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) into MIBK. The recommended procedure was as follows : the samples (20 ∼ 50 g) were dissolved in about 150 ml of water and the solution was filtered through filter paper into a 200-ml volumetric flask. Ten ml of the sample was pipetted into a centrifuge tube, 5 ml of NH3-NH4Cl buffer solution (pH 9.5), and 15 ml 0.05 M HPMBP-MIBK solution were added. The mixture was shaken vigorously for 30 min. After the phases were separated, an 8-ml portion of the organic phase was transferred into another tube and the alkaline earth elements were back-extracted with 8 ml of the 0.1 M hydrochloric acid. The aqueous phase (6 ml) was heated on a hot plate at 100 deg C in order to remove the dissolved MIBK in the phase. After cooling to room temperature, the solution was diluted to 25 ml with water. A 100 μl aliquot of the sample was analyzed by use of an ion chromatograph (Yokogawa Hokushin Electric Works, model IC 100) equipped with a precolumn (PCX 1, 50 mm x 4.6 mm i.d.) and a separation column (SCX 1, 250 mm x 4.6 mm i.d.) by using 2 mM ethylene diamine-4 mM tartaric acid as a mobile phase (2 ml/min). The detection limits (S/N = 2) were 1.5 ppb for Mg2+, 3.4 ppb for Ca2+, 20 ppb for Sr2+ and 50 ppb for Ba2+, respectively. Relative standard deviation (n = 7) was less than 6.3 % for the simultaneous determination of four elements. The recoveries of Mg2+, Ca2+, Sr2+ and Ba2+ by the proposed method were 100 ∼ 105, 95 ∼ 105, 97 ∼ 101 and 95 ∼ 101 %, respectively. (author)

  16. Multi-phase glass-ceramics as a waste form for combined fission products: alkalis, alkaline earths, lanthanides, and transition metals

    International Nuclear Information System (INIS)

    In this study, multi-phase silicate-based glass-ceramics were investigated as an alternate waste form for immobilizing non-fissionable products from used nuclear fuel. Currently, borosilicate glass is the waste form selected for immobilization of this waste stream, however, the low thermal stability and solubility of MoO3 in borosilicate glass translates into a maximum waste loading in the range of 15-20 mass%. Glass-ceramics provide the opportunity to target durable crystalline phases, e.g., powellite, oxyapatite, celsian, and pollucite, that will incorporate MoO3 as well as other waste components such as lanthanides, alkalis, and alkaline earths at levels 2X the solubility limits of a single-phase glass. In addition a glass-ceramic could provide higher thermal stability, depending upon the properties of the crystalline and amorphous phases. Glass-ceramics were successfully synthesized at waste loadings of 42, 45, and 50 mass% with the following glass additives: B2O3, Al2O3, CaO and SiO2 by slow cooling form from a glass melt. Glass-ceramics were characterized in terms of phase assemblage, morphology, and thermal stability. The targeted phases: powellite and oxyapatite were observed in all of the compositions along with a lanthanide borosilicate, and cerianite. Results of this initial investigation of glass-ceramics show promise as a potential waste form to replace single-phase borosilicate glass.

  17. Electrochemical behaviour of alkaline copper complexes

    Indian Academy of Sciences (India)

    C L Aravinda; S M Mayanna; V R Muralidharan

    2000-10-01

    A search for non-cyanide plating baths for copper resulted in the development of alkaline copper complex baths containing trisodium citrate [TSC] and triethanolamine [TEA]. Voltammetric studies were carried out on platinum to understand the electrochemical behaviour of these complexes. In TSC solutions, the deposition of copper involves the slow formation of a monovalent species. Adsorption of this species obeys Langmuir isotherm. In TEA solutions the deposition involves the formation of monovalent ions obeying the non-activated Temkin isotherm. Conversion of divalent to monovalent copper is also slow. In TEA and TSC alkaline copper solutions, the predominant species that undergo stepwise reduction contain only TEA ligands

  18. Dansyl - Substituted Aza Crown Ethers: Complexation with Alkali, Alkaline Earth Metal Ions and Ammonium

    OpenAIRE

    Nelly Mateeva; Shihab Deiab; Edikan Archibong; Donka Tasheva; Bereket Mochona; Madhavi Gangapuram; Kinfe Redda

    2011-01-01

  1. Distribution of alkaline earth elements between aqueous solutions and polymer sorbents impregnated by 8-hydroxyquinoline

    International Nuclear Information System (INIS)

    Interphase distribution of alkaline-earth element (AEE) microimpurities between solutions of alkali metal chlorides and macroporous copolymer of styrene with divinylbenzene impregnated by 8-hydroxyquinoline is investigated. The effect of phase composition on AEE and 8-hydroxyquinoline distribution coefficient is considered. Advantages of the mixture sorption with impregnated sorbent as compared with liquid extraction for thorough purification of salt solution are shown

  2. Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Guangming; YAO Zhenya; ZHAO Jianfu

    2007-01-01

    Catalytic wet air oxidation(CWAO)is one of the most promising technologies for pollution abatement.Developing catalysts with high activity and stability is crucial for the application of the CWAO process.The Mn/Ce complex oxide catalyrsts for CWAO of high concentration phenol containing wastewater were prepared by coprecipitation.The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis.The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller(BET)analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry(ICP-AES).The results show that the catalysts have high catalytic activities even at a low temperature(80℃)and low oxygen partial pressure(0.5 MPa)in a batch reactor.The metallic ion leaching is comparatively low(Mn<6.577 mg/L and Ce<0.6910 mg/L,respectively)in the CWAO process.The phenol,CODCD and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst(named CSP).The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

  3. An Unprecedented 1D Zigzag Chain Alkaline Earth Metal Derivative {[Ba(DMF)3(H2O)2][Ba(DMF)4]2(P2W18O62)}n Containing Dawson Heteropolyanion

    Institute of Scientific and Technical Information of China (English)

    Jing Ping WANG; Jian Ru MA; Jing Yang NIU

    2006-01-01

    An unprecedented 1D zigzag chain alkaline earth metal derivative, {[Ba(DMF)3(H2O)2][Ba(DMF)4]2(P2W18O62)}n, (DMF=N, N-dimethyl formamide) containing Dawson heteropolyanion has been successfully synthesized and characterized by X-ray crystallography. Two barium cations bridged by three DMF ligands in parallel combination with the Dawson-type heteropolyanion [P2W18O62]6- and then the resulting subunits {[Ba(DMF)4]2(P2W18O62)}2+ are alternately linked together via another [Ba(DMF)3(H2O)2]2+ ions, constructing a 1D zigzag chain architecture.

  4. Mechanism of the transfer of alkali- and alkaline-earth-metal ions across the nitrobenzene-water interface facilitated by hexa- and octaethylene glycol dodecyl ethers

    International Nuclear Information System (INIS)

    Transfer of Li+, Na+ , K+, Rb+, Ca2+, Sr2+, and Ba2+ ions facilitated by hexa- and octaethylene glycol monododecyl ethers (C12E6 and C12E8) has been studied at the nitrobenzene (NB)- water (W) interface using cyclic voltammetry. When the concentration of C12En (n = 6 or 8) in NB is higher than 1 mM, cyclic voltammograms for all these ions show reversible transfer of ions facilitated by C12En. The current is mainly carried by 1:1 (metal:ligand) complex and is limited by the diffusion of C12En in NB. When the concentration of C12En in NB is lowered to the submillimolar range, the contribution of the adsorption of C12En to the current becomes significant. In the transfer of hydrophilic ions, e.g., Li + and Ca2+, the contribution of the complex with 1:2 (metal:ligand) stoichiometry to the measured current becomes nonnegligible. This 1:2 complex formation becomes pronounced with increasing ligand concentration

  5. Surface-treatment of Alkaline Earth Sulfides Based Phosphor

    Institute of Scientific and Technical Information of China (English)

    GUO Chong-feng; CHU Ben-li; XU Jian; SU Qiang

    2004-01-01

    A series of alkaline earth sulfides based phosphors Ca0.8Sr0.2S∶Eu2+, Tm3+ were covered with a layer of protective coating with alkaline earth fluorides by heating the mixture of phosphor and NH4HF2 at elevated temperatures. The coatings were characterized by means of XRD and SEM. The optical properties of the coated phosphors and the influences of the coating on their properties have been discussed extensively. The stabilities of the coated and uncoated phosphors have been compared.

  6. Synthesis, structure, and spectroscopic and magnetic properties of mesomorphic octakis(hexylthio)-substituted phthalocyanine rare-earth metal sandwich complexes.

    Science.gov (United States)

    Gürek, Ayse Gül; Basova, Tamara; Luneau, Dominique; Lebrun, Colette; Kol'tsov, Evgeny; Hassan, Aseel K; Ahsen, Vefa

    2006-02-20

    The syntheses of new bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes [(C6S)8-Pc]2M (M = Gd(III), Dy(III), and Sm(III)) (2-4, respectively) are described. These compounds are very soluble in most common organic solvents. They have been fully characterized using elemental analysis, infrared, UV-vis spectroscopy, and mass spectrometry. The crystal structures of compounds 2-4 have been determined by X-ray diffraction on a single crystal. They are isostructural and crystallize in the monoclinic space group (space group C2/c). Their lattice constants have been determined in the following order: (2) a = 31.629(4) Angstroms, b = 32.861(4) Angstroms, c = 20.482(2) Angstroms, beta = 126.922(2) degrees, V = 17019(3) Angstroms(3); (3) a = 31.595(2) Angstroms, b = 32.816(2) Angstroms, c = 20.481(1) Angstroms, beta = 127.005(1) degrees, V = 16958(2) Angstroms(3); (4) a = 31.563(2) Angstroms, b = 32.796(2) Angstroms, c = 20.481(1) Angstroms, beta = 127.032 degrees, V = 16924(2) Angstroms(3). The magnetic properties of compounds 2-4 were studied, and it was revealed that the lanthanide ions and the radical delocalized on the two phthalocyanine rings are weakly interacting. The mesogenic properties of these new materials were studied by differential scanning calorimetry and optical microscopy. These phthalocyanine derivatives form columnar-hexagonal (Col(h)) mesophases. Thin films of bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes (2-4) were prepared by a spin-coating technique. Thermally induced molecular reorganization within films of bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes (2-4) was studied by the methods of ellipsometry, UV-vis absorption spectroscopy, and atomic force microscopy. Heat treatment produces molecular ordering, which is believed to be due to stacking interaction between neighboring phthalocyanine moieties. PMID:16471979

  7. Long-range interactions between alkali and alkaline-earth atoms

    International Nuclear Information System (INIS)

    Dispersion coefficients between the alkali metal atoms (Li–Rb) and alkaline-earth metal atoms (Be–Sr) are evaluated using matrix elements computed from frozen core configuration interaction calculations. Besides dispersion coefficients with both atoms in their respective ground states, dispersion coefficients are also given for the case where one atom is in its ground state and the other atom is in a low-lying excited state. (paper)

  8. Mixed alkaline earth effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.;

    2013-01-01

    While the mixed alkali effect has received significant attention in the glass literature, the mixed alkaline earth effect has not been thoroughly studied. Here, we investigate the latter effect by partial substitution of magnesium for calcium in sodium aluminosilicate glasses. We use Raman and NMR...

  9. Modelling the crystallisation of alkaline earth boroaluminosilicate glass ceramics

    DEFF Research Database (Denmark)

    Svenson, Mouritz Nolsøe; Agersted, Karsten; Holm, Paul Martin

    2014-01-01

    To investigate the potential use of a thermochemical software package (FactSage 6.2), in the design of alkaline earth boroaluminosilicate glass ceramics, experimental and modelled results on four glass ceramics were compared. Initially large discrepancies were found. These are described and related...

  10. Lyoluminescence of luminol in aqueous alkaline metal hydroxides

    International Nuclear Information System (INIS)

    The lyoluminescence emission spectra of luminol, induced by γ-irradiated NaCl in aqueous alkaline earth metal hydroxides, are recorded. Continuous emission bands are observed in the visible region from 390 to 535 nm. These emission bands on resolution showed two peaks at 430 and 460 nm, respectively in all hydroxides. An additional band of 490 appears in the case of calcium hydroxide. The colour centres released during disintegration of irradiated NaCl crystals in aqueous solution react with luminol to produce various excited molecular species, which are responsible for observed lyoluminescence of luminol. (author) 26 refs.; 7 figs.; 1 tab

  11. Determination of complexable metals by chelometric titration

    International Nuclear Information System (INIS)

    A rapid, simple method for the determination of total complexable metal ions (Fe3+, Al3+, Mn2+, Ni2+, Co2+, Pb2+, and Rare Earths) in feed to the Hanford strontium recovery process has been developed. The method consists of complexing the metal ions with EDTA and titrating the excess with copper (II) ion. Pyrocatechol violet is used as a colorimetric end point indicator. Samples of actual process feed were analyzed and the results compared very favorably with results by atomic absorption. Use of a synthetic feed standard showed an average accuracy of 99.7% and a relative precision of +- 1.9% (95% C.L.). Interference studies run on the method show that oxalate and phosphate interfere above mole ratios of 0.1 and 0.3, respectively (anion : total complexable cations). Of the complexable metal ions commonly encountered in this feed (specifically excluding alkali and alkaline-earth metals), the only complexable ion not determinable by this method is Cr

  12. Metallic complexes with glyphosate: a review; Complexos metalicos com o herbicida glifosato: revisao

    Energy Technology Data Exchange (ETDEWEB)

    Coutinho, Claudia F.B.; Mazo, Luiz Henrique [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: claudiabreda@iqsc.usp.br

    2005-11-15

    We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature. (author)

  13. Li2Sr4B12O23: A new alkali and alkaline-earth metal mixed borate with [B10O18]6− network and isolated [B2O5]4− unit

    International Nuclear Information System (INIS)

    A novel ternary lithium strontium borate Li2Sr4B12O23 crystal with size up to 20 mm×10 mm×4 mm has been grown via the top-seeded solution growth method below 730 °C. Single-crystal XRD analyses showed that Li2Sr4B12O23 crystallizes in the monoclinic space group P21/c with a=6.4664(4) Å, b=8.4878(4) Å, c=15.3337(8) Å, β=102.02(3)°, Z=2. The crystal structure is composed of [B10O18]6− network and isolated [B2O5]4− unit. The IR spectrum further confirmed the presence of both BO3 and BO4 groups. TG-DSC and Transmission spectrum were reported. Band structures and density of states were calculated. - Graphical abstract: A new phase, Li2Sr4B12O23, has been discovered in the ternary M2O–M′O–B2O3 (M=alkali-metal, M′=alkalineearth metal) system. The crystal structure consists of [B10O18]6− network and isolated [B2O5]4− unit. Highlights: ► Li2Sr4B12O23 is a a novel borate discovered in the M2O–M′O–B2O3 (M=alkali-metal, M′=alkaline-earth metal) system. ► Li2Sr4B12O23 crystal structure has a three-dimensional crystal structure with [B10O18]6− network and isolated [B2O5]4− unit. ► Sr1 and Sr2 are located in two different channels constructed by 3∞[B10O18] network.

  14. Bose-Einstein condensation of alkaline earth atoms: ;{40}Ca.

    Science.gov (United States)

    Kraft, Sebastian; Vogt, Felix; Appel, Oliver; Riehle, Fritz; Sterr, Uwe

    2009-09-25

    We have achieved Bose-Einstein condensation of ;{40}Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground-state s-wave scattering length of ;{40}Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about 2 x 10;{4} atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less than 3 s. The condensation of an alkaline earth element opens novel opportunities for precision measurements on the narrow intercombination lines as well as investigations of molecular states at the ;{1}S-;{3}P asymptotes. PMID:19905493

  15. Radiation damage and photochromism in the alkaline earth fluorides

    International Nuclear Information System (INIS)

    Detailed mechanisms are proposed for the defect reactions occurring in irradiated alkaline earth fluorides. Both pure and doped crystals are considered. For the former, the models rationalise much of the experimental data, particularly the studies of Hayes and Lambourn. The discussion of doped crystals explains the origin of the pronounced effects of trivalent impurities. The mechanism of formation of photochromic centres is discussed and the observed temperature dependence of the stability of these defects is explained successfully. (author)

  16. Distribution of alkaline earth elements between aqueous solutions and polymeric sorbent impregnated with 8-hydroxyquinoline

    International Nuclear Information System (INIS)

    The interphase distribution of microimpurities of alkaline earth elements (AEE) between solutions of alkali metal chlorides and a macroporous styrene-divinyl-benzene copolymer impregnated with 8-hydroxyquinoline was studied. The influence of the phase composition on the distribution coefficients of AEE and 8-hydroxyquinoline was examined. The advantages of sorption of the impurities by an impregnated sorbent over liquid extraction for thorough purification of salt solutions were shown

  17. Design and Synthesis of Redox-Switched Lariat Ethers and Their Application for Transport of Alkali and Alkaline-Earth Metal Cations Across Supported Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Uma Sharma

    2006-08-01

    Full Text Available A new class of redox-switched anthraquinone derived lariat ethers 1-(1-anthraquinonyloxy 3, 6, 9 trioxaundecane 11-ol (M1, 1-(1-anthraquinonyloxy 3, 6 dioxaoctane 9-ol (M2, 1-(1-anthraquinonyloxy 3 oxapentane 5-ol (M3, 1-(1-anthraquinonyloxy 3 oxapentane 5-butane (M4, 1-(1-anthraquinonyloxy 3, 6 dioxaoctane 9-methane (M5 and 1-(1-anthraquinonyloxy 3 oxapentane 5-methane (M6 have been synthesized and characterized by spectral analysis. These ionophores were used in liquid membrane carrier facilitated transport of main group metal cations across supported liquid membrane (SLM. Cellulose nitrate membrane was used as membrane support. Effect of various parameters such as variation in concentration of metal as well as ionophore, effect of chain length and end group of ionophore have been studied. The sequence of metal ions transported by ionophore M1 is Na+ > Li+ > K+ > Ca2+ > Mg2+ and the order of metal ions transported by ionophores (M2–M6 is Li+ > Na+ > K+ > Ca2+ > Mg2+. Ionophore M1 is selective for Na+, Li+, and K+ and ionophores (M2–M6 are selective for Li+ and Na+.

  18. Theoretical survey on M@C80 (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

    Science.gov (United States)

    Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang

    2016-08-01

    Structures of mono-metallofullerenes M@C80 (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C2v(31920)-C80 cage. The change rule of properties for M@C80 (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C2v(31920)-C80, M@C2v(31922)-C80, and M@D5h(31923)-C80 are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C2v(31920)-C80 and Ca@D5h(31923)-C80 are mostly located on the trapped metal, whereas reduction reactions of Ca@C2v(31920)-C80 and Ca@D5h(31923)-C80 occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C2v(31920)-C80 would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV-visible-NIR spectra for M@C2v(31920)-C80 (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

  19. Correlation-induced metal-insulator transitions in d0 magnetic superlattices based on alkaline-earth monoxides: Insights from ab initio calculations

    Science.gov (United States)

    Lu, Yi-Lin; Dong, Shengjie; Zhou, Baozeng; Zhao, Hui; Wu, Ping

    2015-06-01

    Using first-principles density functional theory calculations, we have investigated the electronic structure and magnetic properties of four superlattices (MO)1/(MX)1 (001) (M=Ca and Sr; X=N and C). Our results show that compared with standard GGA approach, the GGA plus effective Ueff scheme can correct electronic structure and magnetic properties in some extent. With enhancing electronic correlation, for (CaO)1/(CaN)1, (SrO)1/(SrN)1, and (SrO)1/(SrC)1, the bands across Fermi level are divided into two parts and the shape of isotropic spherical spin atmosphere becomes anisotropic dumbbell-like with specific orientation, accompanying metal-insulator transitions. For (CaO)1/(CaC)1, the states just smearing with the Fermi level shift to lower energy region below Fermi level, indicating the transformation from a nearly half metal to an actual half metal occurs. The different behavior of (CaO)1/(CaC)1 compared with three other compounds may be caused by the larger ionization energy of calcium than that of strontium and the smaller electronegativity of carbon than that of nitrogen.

  20. Synthesis, characterization, antibacterial and antifungal studies of some transition and rare earth metal complexes of N-benzylidene-2-hydroxybenzohydrazide

    Directory of Open Access Journals (Sweden)

    T.K. Chondhekar

    2011-12-01

    Full Text Available The solid complexes of Cu(II, Co(II, Mn(II, La(III and Ce(III were prepared from bidentate Schiff base, N-benzylidene-2-hydroxybenzohydrazide. The Schiff base ligand was synthesized from 2-hyhdroxybenzohydrazide and benzaldehyde. These metal complexes were characterized by molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, FTIR, 1H-NMR, UV-Vis and mass spectroscopy. The analytical data of these metal complexes showed metal:ligand ratio of 1:2. The physico-chemical study supports the presence of square planar geometry around Cu(II and octahedral geometry around Mn(II, Co(II, La(III and Ce(III ions. The IR spectral data reveal that the ligand behaves as bidentate with ON donor atom sequence towards central metal ion. The molar conductance values of metal complexes suggest their non-electrolyte nature. The X-ray diffraction data suggest monoclinic crystal system for these complexes. Thermal behavior (TG/DTA and kinetic parameters calculated by Coats-Redfern method are suggestive of more ordered activated state in complex formation. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungicidal activity against Aspergillus niger and Trichoderma.

  1. Quantum mechanics and molecular dynamics simulations of complexation of alkaline-earth and lanthanide cations by poly-amino-carboxylate ligands; Simulations par mecanique quantique et dynamique moleculaire de la complexation de cations alcalino-terreux et lanthanides par des ligands polyaminocarboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Durand, S

    1999-07-01

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA{sup 4-}, ethylene-diamino-tri-acetate-acetic acid EDTA(H){sup 3-}, tetra-aza-cyclo-dodecane-tetra-acetate DOTA{sup 4-}, methylene-imidine-acetate MIDA{sup 2-}) are reported. First, a consistent set of Lennard-Jones parameters for La{sup 3+}, Eu{sup 3+} and Lu{sup 3+} cations has been derived from free energy calculations in aqueous solution. Observed differences in hydration free energies, coordination distances and hydration numbers are reproduced. Then, the solution structures of 1:1 complexes of alkaline-earth and/or lanthanide cations with EDTA{sup 4-}, EDTA(H){sup 3-}, DOTA{sup 4-} and 1:2 complexes of lanthanide cations with MIDA{sup 2-} were studied by MD in water. In addition, free energy calculations were performed to study, for each ligand, the relative thermodynamic stabilities of complexes with Ca{sup 2+} vs Sr{sup 2+} and vs Ba{sup 2+} on the one hand, and with La{sup 3+} vs Eu{sup 3+} and vs Lu{sup 3+} on the other hand. Model does not take into account explicitly polarization and charge transfer. However, the results qualitatively agree with experimental complexation data (structure and selectivities). (author)

  2. A study on equilibrium and kinetics of ion exchange of alkaline earth metals using an inorganic cation exchanger - zirconium titanium phosphate

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

    An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate (ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of exchange is particle diffusion, as confirmed by the linear (dimensionless time parameter) vs (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied herein. Further, various kinetic parameters like self-diffusion coefficient (0), energy of activation () and entropy of activation (*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism.

  3. Density functional study on the ferromagnetism of alkaline earth doped InN

    International Nuclear Information System (INIS)

    Highlights: • The magnetic properties of alkaline earth doped InN were systematically investigated. • The doped system transits from nonmagnetic state to half-metallic state. • Strong ferromagnetism can be expected in Sr- or Ba-doped InN. • Under nitrogen-rich condition, the defect is more stable. - Abstract: Recently, p-type conduction of InN doped by alkaline earth was reported in experiments. However, the magnetic property of the doped systems has not been studied. We systematically investigate the magnetic property of alkaline-earth doped InN by density-functional theory. Our results reveal that the ground state of the doped system transits from nonmagnetic state to spin-polarized state, and the holes introduced into the valence band become more localized as the defect ranges from Be to Ba. As a result, strong half-metallic ferromagnetism emerges for Sr- or Ba-doped InN. Our calculations reveal that the formation energy of defect is much lower for nitrogen-rich condition, under which the doped system can be favorably synthesized

  4. Density functional study on the ferromagnetism of alkaline earth doped InN

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai-Cheng, E-mail: kczhang@yeah.net [College of Mathematics and Physics, Bohai University, Jinzhou 121013 (China); Li, Yong-Feng [Key laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Liu, Yong [State Key Laboratory of Metastable Materials Science and Technology and College of Science, Yanshan University, Qinhuangdao, Hebei 066004 (China); Zhu, Yan [Department of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2015-03-15

    Highlights: • The magnetic properties of alkaline earth doped InN were systematically investigated. • The doped system transits from nonmagnetic state to half-metallic state. • Strong ferromagnetism can be expected in Sr- or Ba-doped InN. • Under nitrogen-rich condition, the defect is more stable. - Abstract: Recently, p-type conduction of InN doped by alkaline earth was reported in experiments. However, the magnetic property of the doped systems has not been studied. We systematically investigate the magnetic property of alkaline-earth doped InN by density-functional theory. Our results reveal that the ground state of the doped system transits from nonmagnetic state to spin-polarized state, and the holes introduced into the valence band become more localized as the defect ranges from Be to Ba. As a result, strong half-metallic ferromagnetism emerges for Sr- or Ba-doped InN. Our calculations reveal that the formation energy of defect is much lower for nitrogen-rich condition, under which the doped system can be favorably synthesized.

  5. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    Science.gov (United States)

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  6. Bose-Einstein condensation of alkaline earth atoms: $^{40}${Ca}

    OpenAIRE

    Kraft, Sebastian; Vogt, Felix; Appel, Oliver; Riehle, Fritz; Sterr, Uwe

    2009-01-01

    We have achieved Bose-Einstein condensation of $^{40}$Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground state s-wave scattering length of $^{40}$Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about $2 \\cdot 10^4$ atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less ...

  7. Study on rare earth/alkaline earth oxide-doped CeO2 solid electrolyte

    Institute of Scientific and Technical Information of China (English)

    YAN Kai; ZHEN Qiang; Song Xiwen

    2007-01-01

    Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the Sm2O3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Sm0.20Ce0.8O1.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the Arrhenius equation. Then the Sm2O3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.

  8. Rb-Sr age of the Sivamalai alkaline complex, Tamil Nadu

    International Nuclear Information System (INIS)

    The Sivamalai alkaline complex comprises ferro-, pyroxene- hornblende-and nepheline-syenites. Field relations show that the nepheline syenites followed the emplacement of non-feldspathoidal syenites. Mineralogical data on the syenite suite have been reviewed. The Sivamalai alkaline rocks are not strongly enriched in rare-earth elements like most miaskites. Rb-Sr isotopic analyses of a suite of six samples from the various members of the complex define an isochron corresponding to an age of 623 ± 21 Ma (2σ) and initial Sr ratio of 0.70376 ± 14 (2σ). This is consistent with a model of fractional crystallization of a parent magma derived from an upper mantle source with apparently no isotopic evidence for more than one magma source for the complex. The Sivamalai alkaline complex represents a Pan-African alkaline magmatic event in the southern granulite terrane of peninsular India. (author). 26 refs., 4 figs., 4 tabs

  9. The influence of complexing pharmaceutical compositions on alkaline phosphatase

    Science.gov (United States)

    Atyaksheva, L. F.; Chukhrai, E. S.; Stepina, N. D.; Novikova, N. N.; Yur'eva, E. A.

    2011-06-01

    It is established that the pharmaceutical compositions xydiphon, medifon, succimer, and EDTA, which are used as complexing agents for accelerating the excretion of heavy metals from human organism, at certain concentrations inhibit enzyme alkaline phosphatase (AP). It is concluded that xydiphon and EDTA have a noticeable effect on AP activity at concentrations over 0.01 mM; medifon and succimer, at concentrations of over 0.3-0.5 mM. The enzyme's inhibition constants and type of inhibition are determined. Xydiphon is found to manifest the highest affinity to AP ( K I = 0.35 mM). It is shown by kinetic analysis that dissociative chemoinactivation of the enzyme takes place under the action of complexing agents. The corresponding kinetic parameters are calculated.

  10. Study of conformational and acid-base properties of norbadione A and pulvinic derivatives: Consequences on their complexation properties of alkaline and alkaline earth cations; Etude des proprietes conformationnelles et acido-basiques de la norbadione A et de derives pulviniques: consequences sur leurs proprietes complexantes de cations alcalins et alcalino-terreux

    Energy Technology Data Exchange (ETDEWEB)

    Kuad, P

    2006-01-15

    This work deals with the study of norbadione A, a pigment extracted from mushrooms and known to complex cesium cations. The study of the acid-base properties of norbadione A has allowed to determine the relative acidity of the seven protonable functions of the molecule and to reveal a reversible isomerization of the double exocyclic bond of the pulvinic moieties. The observed change of configuration is induced by a hydrogen bond of the H-O-H type and by electrostatic interactions. Moreover, the microscopic protonation mechanism of the norbadione A has been analyzed, considering three different study media where the acid-base properties of the norbadione A are compared. In the presence of 0.15 mol.l{sup -1} of NaCl, it has been observed a remarkable cooperativity in the protonation of the enol groups. At last, the use of different analytical methods (NMR, potentiometry and calorimetry) has allowed to study the complexing properties of the norbadione A towards cesium and other alkaline and rare earth cations. (O.M.)

  11. Attaching an alkali metal atom to an alkaline earth metal oxide (BeO, MgO, or CaO) yields a triatomic metal oxide with reduced ionization potential and redirected polarity.

    Science.gov (United States)

    Nowiak, Grzegorz; Skurski, Piotr; Anusiewicz, Iwona

    2016-04-01

    The existence of a series of neutral triatomic metal oxides MON and their corresponding cations MON (+) (M = Be, Mg, Ca; N = Li, Na, K) was postulated and verified theoretically using ab initio methods at the CCSD(T)/6-311+G(3df)//MP2/6-311+G(3df) level of theory. The calculations revealed that the vertical ionization potentials (IPs) of the MON radicals (calculated using the outer-valence Green's function technique (OVGF) with the 6-311+G(3df) basis set) were ca. 2-3 eV smaller than the IPs of the corresponding MO and NO systems or that of the isolated M atom. Population analysis of the neutral triatomic MON molecules and their corresponding MO counterparts indicated that the attachment of an alkali metal atom to any oxide MO (BeO, MgO, CaO) reverses its polarity, which manifests itself as the redirection of the dipole moment vector. PMID:26994021

  12. Effect of rare earth oxides on the properties of bio-soluble alkaline earth silicate fibers

    Institute of Scientific and Technical Information of China (English)

    王玺堂; 刘浩; 王周福; 马妍

    2016-01-01

    Using natural mineral wollastonite, talc and quartz sands as raw materials, rare earth oxides (La2O3, Nd2O3 and Y2O3) as additives, the bio-soluble alkaline earth silicate fibers were prepared by melting and blowing process. The viscosity of the molten ma-terials, bio-solubility and crystallization behavior of the fiber were investigated. The results indicated that the fiber drawing tempera-ture range could be broadened since the slope of the temperature-viscosity curve decreased with adding rare earth oxide. The addition of rare earth oxide was beneficial to the increase of crystallization temperature by strengthening the network structure of the fiber. The existence of rare earth oxide in the fibers would reduce the solubility of the fibers, which still belonged to bio-soluble fibers.

  13. Tune-out wavelengths for the alkaline earth atoms

    CERN Document Server

    Cheng, Yongjun; Mitroy, Jim

    2013-01-01

    The lowest 3 tune-out wavelengths of the four alkaline-earth atoms, Be, Mg, Ca and Sr are determined from tabulations of matrix elements produced from large first principles calculations. The tune-out wavelengths are located near the wavelengths for $^3P^o_1$ and $^1P^o_1$ excitations. The measurement of the tune-out wavelengths could be used to establish a quantitative relationship between the oscillator strength of the transition leading to existence of the tune-out wavelength and the dynamic polarizability of the atom at the tune-out frequency. The longest tune-out wavelengths for Be, Mg, Ca, Sr, Ba and Yb are 454.9813 nm, 457.2372 nm, 657.446 nm, 689.200 nm, 788.875 nm and 553.00 nm respectively.

  14. Deep optical trap for cold alkaline-Earth atoms.

    Science.gov (United States)

    Cruz, Luciano S; Sereno, Milena; Cruz, Flavio C

    2008-03-01

    We describe a setup for a deep optical dipole trap or lattice designed for holding atoms at temperatures of a few mK, such as alkaline-Earth atoms which have undergone only regular Doppler cooling. We use an external optical cavity to amplify 3.2 W from a commercial single-frequency laser at 532 nm to 523 W. Powers of a few kW, attainable with low-loss optics or higher input powers, allow larger trap volumes for improved atom transfer from magneto-optical traps. We analyze possibilities for cooling inside the deep trap, the induced Stark shifts for calcium, and a cancellation scheme for the intercombination clock transition using an auxiliary laser. PMID:18542375

  15. Optical tuning of the scattering length of cold alkaline earth atoms

    OpenAIRE

    Ciurylo, R.; Tiesinga, E.; P.S. Julienne

    2004-01-01

    It is possible to tune the scattering length for the collision of ultra-cold 1S0 ground state alkaline-earth atoms using an optical Feshbach resonance. This is achieved with a laser far detuned from an excited molecular level near the frequency of the atomic intercombination 1S0--3P1 transition. Simple resonant scattering theory, illustrated by the example of 40Ca, allows an estimate of the magnitude of the effect. Unlike alkali metal species, large changes of the scattering length are possib...

  16. Porphyrin-Alkaline Earth MOFs with the Highest Adsorption Capacity for Methylene Blue.

    Science.gov (United States)

    Hou, Yuxia; Sun, Junshan; Zhang, Daopeng; Qi, Dongdong; Jiang, Jianzhuang

    2016-04-25

    A series of four porphyrin-alkaline earth metal- organic frameworks [Mg(HDCPP)2 (DMF)2 ]n ⋅(H2 O)7 n (1), [Ca(HDCPP)2 (H2 O)2 ]n (DMF)1.5 n (2), [Sr(DCPP)(H2 O)(DMA)]n (3), and [Ba(DCPP)(H2 O)(DMA)]n (4) was isolated for the first time from solvothermal reaction between metal-free 5,15-di(4- carboxyphenyl)porphyrin (H2 DCPP) and alkaline earth ions. Single-crystal X-ray diffraction analysis reveals the 2D and 3D supramolecular network with periodic nanosized porosity for 1/2 and 3/4, respectively. The whole series of MOFs, in particular, compounds 1 and 2 with intrinsic low molecular formula weight, exhibit superior adsorption performance for methylene blue (MB) with excellent capture capacity as represented by the thus far highest adsorption amount of 952 mg g(-1) for 2 and good selectivity, opening a new way for the potential application of the main group metal-based MOFs. PMID:27002679

  17. Thermochemical properties of two mixed alkali-alkaline earth metal borates as non-linear optical materials: NaSrBO3 and KSr4B3O9

    International Nuclear Information System (INIS)

    Highlights: • NaSrBO3 and KSr4B3O9 have been synthesized and characterized. • The enthalpies of solution of title two borates in 1 mol · dm−3 HCl(aq) were measured. • The enthalpies of solution of NaCl(s) in [HCl + H3BO3 + Sr(OH)2 · 8H2O](aq) were measured. • ΔfHmo for title borates were obtained from measured enthalpies of solution. -- Abstract: Two mixed alkali-alkaline earth metal borates of NaSrBO3 and KSr4B3O9 have been synthesized by high-temperature solid state reaction, which were further characterized by XRD, FT-IR, DTA-TG techniques and chemical analysis. The molar enthalpies of solution of NaSrBO3(s) and KSr4B3O9(s) in 2.00 cm3 of 1 mol · dm−3 HCl(aq), at T = 298.15 K were measured to be −(206.84 ± 0.43) kJ · mol−1 and −(494.59 ± 0.53) kJ · mol−1, respectively. The molar enthalpy of solution of NaCl(s) in 2.00 cm3 of {1 mol · dm−3 HCl + H3BO3 + Sr(OH)2 · 8H2O}(aq) mixed solvent at T = 298.15 K was measured to be (5.17 ± 0.02) kJ · mol−1. From these data and with the incorporation of the previously determined enthalpies of solution of H3BO3(s) in HCl(aq) of Sr(OH)2 · 8H2O(s) in (HCl + H3BO3)(aq), and of KCl(s) in {HCl + H3BO3 + Sr(OH)2 · 8H2O}(aq), together with the use of the molar enthalpies of formation for NaCl(s)/KCl(s), Sr(OH)2 · 8H2O(s), H3BO3(s), HCl(aq) and H2O(l), the standard molar enthalpies of formation of NaSrBO3(s) and KSr4B3O9 were calculated to be −(1653.1 ± 1.4) kJ · mol−1 and −(5071.1 ± 3.4) kJ · mol−1 on the basis of the designed thermochemical cycles, respectively

  18. Structure elucidation of alkaline earth impregnated MCM-41 type mesoporous materials obtained by direct synthesis: An experimental and theoretical study

    Science.gov (United States)

    Paz, Gizeuda L.; Silva, Francisco das Chagas M.; Araújo, Maciel M.; Lima, Francisco das Chagas A.; Luz, Geraldo E.

    2014-06-01

    In this work, MCM-41 were synthesized hydrothermally and functionalized with calcium and strontium salts by direct method, using the Si/M = 50 molar ratio, in order to elucidate the way as the alkaline earth is incorporated on MCM-41 molecular sieve. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nitrogen adsorption-desorption and theoretical calculations by DFT method. Experimental results and computer simulations showed that the alkaline earths were incorporated on MCM-41 through a complex structure, which negatively influences on basic sites formation.

  19. Alkaline-Earth-Catalysed Cross-Dehydrocoupling of Amines and Hydrosilanes: Reactivity Trends, Scope and Mechanism.

    Science.gov (United States)

    Bellini, Clément; Dorcet, Vincent; Carpentier, Jean-François; Tobisch, Sven; Sarazin, Yann

    2016-03-18

    Alkaline-earth (Ae=Ca, Sr, Ba) complexes are shown to catalyse the chemoselective cross-dehydrocoupling (CDC) of amines and hydrosilanes. Key trends were delineated in the benchmark couplings of Ph3 SiH with pyrrolidine or tBuNH2 . Ae{E(SiMe3 )2 }2 ⋅(THF)x (E=N, CH; x=2-3) are more efficient than {N^N}Ae{E(SiMe3 )2 }⋅(THF)n (E=N, CH; n=1-2) complexes (where {N^N}(-) ={ArN(o-C6 H4 )C(H)=NAr}(-) with Ar=2,6-iPr2 -C6 H3 ) bearing an iminoanilide ligand, and alkyl precatalysts are better than amido analogues. Turnover frequencies (TOFs) increase in the order Ca30 products) includes diamines and di(hydrosilane)s. Kinetic analysis of the Ba-promoted CDC of pyrrolidine and Ph3 SiH shows that 1) the kinetic law is rate=k[Ba](1) [amine](0) [hydrosilane](1) , 2) electron-withdrawing p-substituents on the arylhydrosilane improve the reaction rate and 3) a maximal kinetic isotopic effect (kSiH /kSiD =4.7) is seen for Ph3 SiX (X=H, D). DFT calculations identified the prevailing mechanism; instead of an inaccessible σ-bond-breaking metathesis pathway, the CDC appears to follow a stepwise reaction path with N-Si bond-forming nucleophilic attack of the catalytically competent Ba pyrrolide onto the incoming silane, followed by rate limiting hydrogen-atom transfer to barium. The participation of a Ba silyl species is prevented energetically. The reactivity trend Cametal centre and decreasing Ae-Namide bond strength upon descending Group 2. PMID:26864122

  20. Metal complexes with non-innocent N-donor Ligands: molecular and electronic structures, reactivity, and application

    OpenAIRE

    Khusniyarov, Marat

    2006-01-01

    The present work comprises different aspects of coordination chemistry of non-innocent, or redox active, ligands. The most attention is given to the complexes of late transition metals as well as phthalocyanines of alkaline earth metals. The dissertation covers synthesis of complexes with non-innocent ligands and investigation of their molecular and electronic structures by set of methods including X-ray crystallography, EPR, NMR ...

  1. Method for synthesizing metal bis(borano) hypophosphite complexes

    Science.gov (United States)

    Cordaro, Joseph G.

    2013-06-18

    The present invention describes the synthesis of a family of metal bis(borano) hypophosphite complexes. One procedure described in detail is the syntheses of complexes beginning from phosphorus trichloride and sodium borohydride. Temperature, solvent, concentration, and atmosphere are all critical to ensure product formation. In the case of sodium bis(borano) hypophosphite, hydrogen gas was evolved upon heating at temperatures above 150.degree. C. Included in this family of materials are the salts of the alkali metals Li, Na and K, and those of the alkaline earth metals Mg and Ca. Hydrogen storage materials are possible. In particular the lithium salt, Li[PH.sub.2(BH.sub.3).sub.2], theoretically would contain nearly 12 wt % hydrogen. Analytical data for product characterization and thermal properties are given.

  2. Solvent extraction of alkaline earth elements by di-2-ethylhexylphosphoric acid and 8-hydroxyquinoline mixtures

    International Nuclear Information System (INIS)

    Solvent extraction of alkaline earth elements including Sr by mixtures of di-2-ethylhexylphosphoric acid and 8-hydroxyquinoline (8-O) in chloroform is investigated. pH constant value was kept using acetate buffer mixtures; content of the extracted element in the initial solution constituted 1·10-3mol/l. Investigation into dependence of distribution coefficients on (8-O) concentration demonstrated presence of synergism which is explained by formation of mixed complexes in the organic phase. It is shown, that increase of pH value of aqueous solution uncreases extraction of elements by organic phase

  3. Heavy metals quantification on alkaline batteries incineration emissions

    OpenAIRE

    Xará, Susana; Almeida, Manuel Fonseca; Costa, Carlos; Silva, Margarida

    2000-01-01

    Heavy metals emissions associated with municipal solid waste (MSW) incineration is a point of discussion and care due to the known harmful effects of these metals on humans and environment. Batteries are appointed as one of the main contributors for those emissions, particularly for mercury, cadmium, zinc and lead. In this paper, results for heavy metals emissions from alkaline batteries obtained in a laboratorial incinerator are presented. The incineration process took place in a tubular ove...

  4. Synthesis, structure peculiarities and electric conductivity of alkali metal-rare earth silicates (germanates)

    International Nuclear Information System (INIS)

    The process of obtaining of rare earth-alkali metal silicates (germanates) is studied. The analysis of possibilities of structural disordering of alkaline cations in these structures is given. The interaction of the structure of different by the composition alkali alkali metal - rare earth silicates with electric conductivity values is shown

  5. Conducting metal dithiolate complexes

    DEFF Research Database (Denmark)

    Underhill, A. E.; Ahmad, M. M.; Turner, D. J.; Clemenson, P. I.; Carneiro, K.; Yueqiuan, S.; Mortensen, Kell

    Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound......Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound...

  6. Conducting metal dithiolate complexes

    DEFF Research Database (Denmark)

    Underhill, A. E.; Ahmad, M. M.; Turner, D. J.;

    1985-01-01

    Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound......Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound...

  7. Oligocyclopentadienyl transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    de Azevedo, Cristina G.; Vollhardt, K. Peter C.

    2002-01-18

    Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

  8. IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

    Science.gov (United States)

    De Visscher, Alex; Vanderdeelen, Jan; Königsberger, Erich; Churagulov, Bulat R.; Ichikuni, Masami; Tsurumi, Makoto

    2012-03-01

    The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO3), nesquehonite (MgCO3.3H2O), and lansfordite (MgCO3.5H2O), a critical evaluation is presented based on curve fits to empirical and/or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO2 with Sechenov parameters, and for various equilibria in the aqueous phase including the dissociation constants of CO2(aq) and the stability constant of the ion pair MCO30(aq) (M = alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consistent with two thermodynamic model variants are proposed. The model variant that describes the Mg2+-HCO3- ion interaction with Pitzer parameters was more consistent with the solubility data and with other thermodynamic data than the model variant that described the interaction with a stability constant.

  9. Electromigration in molten salts and application to isotopic separation of alkaline and alkaline-earth elements

    International Nuclear Information System (INIS)

    The separation of the isotopes of the alkaline-earth elements has been studied using counter-current electromigration in molten bromides. The conditions under which the cathode operates as a bromine electrode for the highest possible currents have been examined. For the separation of calcium, it has been necessary to use a stable CaBr2 - (CaBr2 + KBr) 'chain'. In the case of barium and strontium, it was possible to employ the pure bromides. Enrichment factors of the order of 10 for 48Ca and of the order of 1.5 for the rare isotopes of barium and strontium have been obtained. In the case of magnesium the method is slightly more difficult to apply because of material loss due to the relatively high vapour pressure of the salt requiring the use of electrolyte chains, MgBr2 - CeBr3. A study has been made that has led to a larger-scale application of the method. These are essentially the inhibition of reversible operation of the cathode by traces of water, limiting the intensity which can be tolerated; evacuation of the heat produced by the Joule effect, in the absence of which the separation efficiency is reduced by thermal gradients; corrosion of the materials by molten salts at high temperature. Several cells capable of treating a few kilograms of substance have been put into operation; none of these has lasted long enough to produce a satisfactory enrichment. The method is thus limited actually to yields of the order of a few grams. (author)

  10. The significance of secondary interactions during alkaline earth-promoted dehydrogenation of dialkylamine-boranes.

    Science.gov (United States)

    Bellham, Peter; Anker, Mathew D; Hill, Michael S; Kociok-Köhn, Gabriele; Mahon, Mary F

    2016-09-21

    Reactions of anilidoimine magnesium n-butyl and calcium bis(trimethylsilyl)amide derivatives with Me2NH·BH3 at 25 °C resulted in the isolation of complexes containing [NMe2BH2NMe2BH3](-) and [NMe2BH3](-) anions respectively. Although onward reaction of the calcium species at 30 °C with a further equivalent of Me2NH·BH3 provided ca. 90% conversion of the coordinated dimethylamidoborane anion to [NMe2BH2NMe2BH3](-), this process also resulted in significant (ca. 25%) levels of competitive protonation of the anilidoimine spectator ligand. A similar reaction performed between a previously reported β-diketiminato calcium dimethylamidoborane and Me2NH·BH3, however, provided clean conversion to a structurally characterised calcium [NMe2BH2NMe2BH3](-) complex. Reaction of a more sterically congested β-diketiminato magnesium n-butyl reagent with Me2NH·BH3 has allowed the isolation of a magnesium derivative of the [NMe2BH3](-) anion. The thermal stability of these compounds as well as previously reported magnesium and calcium amidoborane species indicate, in partial agreement with a recent DFT study, that all of these compounds are resistant to the β- and δ-hydride elimination reactions that have previously been implicated as the key B-N bond-forming and dehydrogenative steps in the group 2-catalysed dehydrocoupling of Me2NH·BH3. In contrast to these observations, addition of stoichiometric quantities of Me2NH·BH3 to the various isolated group 2 amidoborane species was found to result in facile elimination of the cyclic borazane [Me2N-BH2]2 which occurs with regeneration of the metallated amidoborane. On this basis, we suggest that the dehydrocoupling of Me2NH·BH3 at group 2 centres takes place as a sequence of concerted proton-assisted steps during which B-H and N-H bond breaking plays an equally prominent role, with the efficacy of boron hydride protonolysis dictated by the relative polarising influence of the B-H to Mg/Ca interactions. Furthermore, we propose

  11. Rare-earth metal methylidene complexes with Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 core structure.

    Science.gov (United States)

    Schädle, Dorothea; Meermann-Zimmermann, Melanie; Maichle-Mössmer, Cäcilia; Schädle, Christoph; Törnroos, Karl W; Anwander, Reiner

    2015-11-01

    Trinuclear rare-earth metal methylidene complexes with a Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 structural motif were synthesized by applying three protocols. Polymeric [LuMe3]n (1-Lu) reacts with the sterically demanding amine H[NSiMe3(Ar)] (Ar = C6H3iPr2-2,6) in tetrahydrofuran via methane elimination to afford isolable monomeric [NSiMe3(Ar)]LuMe2(thf)2 (4-Lu). The formation of trinuclear rare-earth metal tetramethyl methylidene complexes [NSiMe3(Ar)]3Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3(thf)3 (7-Ln; Ln = Y, Ho, Lu) via reaction of [LnMe3]n (1-Ln; Ln = Y, Ho, Lu) with H[NSiMe3(Ar)] is proposed to occur via an "intermediate" species of the type [NSiMe3(Ar)]LnMe2(thf)x and subsequent C-H bond activation. Applying Lappert's concept of Lewis base-induced methylaluminate cleavage, compounds [NSiMe3(Ar)]Ln(AlMe4)2 (5-Ln; Ln = Y, La, Nd, Ho) were converted into methylidene complexes 7-Ln (Ln = Y, Nd, Ho) in the presence of tetrahydrofuran. Similarly, tetramethylgallate complex [NSiMe3(Ar)]Y(GaMe4)2 (6-Y) could be employed as a synthesis precursor for 7-Y. The molecular composition of complexes 4-Ln, 5-Ln, 6-Y and 7-Ln was confirmed by elemental analyses, FTIR spectroscopy, (1)H and (13)C NMR spectroscopy (except for holmium derivatives) and single-crystal X-ray diffraction. The Tebbe-like reactivity of methylidene complex 7-Nd with 9-fluorenone was assessed affording oxo complex [NSiMe3(Ar)]3Nd3(μ3-O)(μ2-Me)4(thf)3 (8-Nd). The synthesis of 5-Ln yielded [NSiMe3(Ar)]2Ln(AlMe4) (9-Ln; Ln = La, Nd) as minor side-products, which could be obtained in moderate yields when homoleptic Ln(AlMe4)3 were treated with two equivalents of K[NSiMe3(Ar)]. PMID:26418665

  12. Theoretical study of the dipole moments of selected alkaline-earth halides

    Science.gov (United States)

    Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.; Ahlrichs, R.

    1986-01-01

    Ab initio calculations at the self-consistent-field (SCF), singles-plus-doubles configuration-interaction (SDCI), and coupled-pair functional (CPF) level, are reported for the dipole moments and dipole derivatives of the X2Sigma(+) ground states of BeF, BeCl, MgF, MgCl, CaF, CaCl, and SrF. For comparison, analogous calculations are performed for the X1Sigma(+) state of KCl. The CPF results are found to be in remarkably better agreement with experiment than are the SCF and SDCI results. Apparently higher excitations are required to properly describe the radial extent along the bond axis of the remaining valence electron on the alkaline-earth metal.

  13. Optical tuning of the scattering length of cold alkaline earth atoms

    CERN Document Server

    Ciurylo, R; Julienne, P S

    2004-01-01

    It is possible to tune the scattering length for the collision of ultra-cold 1S0 ground state alkaline-earth atoms using an optical Feshbach resonance. This is achieved with a laser far detuned from an excited molecular level near the frequency of the atomic intercombination 1S0--3P1 transition. Simple resonant scattering theory, illustrated by the example of 40Ca, allows an estimate of the magnitude of the effect. Unlike alkali metal species, large changes of the scattering length are possible while atom loss remains small, because of the very narrow line width of the molecular photoassociation transition. This raises prospects for control of atomic interactions for a system without magnetically tunable Feshbach resonance levels.

  14. Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor.

    Science.gov (United States)

    Kim, Doory; Kim, Han-Eol; Kim, Chang-Hong

    2016-01-01

    Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors. PMID:26731086

  15. Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor.

    Directory of Open Access Journals (Sweden)

    Doory Kim

    Full Text Available Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4 gave the brightest and longest emissions (11% and 9% increase for each. Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4 alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4 boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors.

  16. Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor

    Science.gov (United States)

    Kim, Doory; Kim, Han-Eol; Kim, Chang-Hong

    2016-01-01

    Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors. PMID:26731086

  17. Petrogenesis of coeval silica-saturated and silica-undersaturated alkaline rocks: Mineralogical and geochemical evidence from the Saima alkaline complex, NE China

    Science.gov (United States)

    Zhu, Yu-Sheng; Yang, Jin-Hui; Sun, Jin-Feng; Zhang, Ji-Heng; Wu, Fu-Yuan

    2016-03-01

    A combined study of zircon U-Pb ages, mineral chemistry, whole-rock elements and Sr-Nd-Hf isotopes was carried out for the Saima alkaline complex in the northeastern China, in order to investigate the source and petrogenesis of coeval silica-saturated and silica-undersaturated alkaline rocks. The Saima alkaline complex consists of nepheline syenites, quartz-bearing syenites and alkaline volcanic rocks (i.e., phonolite and trachyte), with minor mafic dikes and carbonatitic veins. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and secondary ion mass spectrometry (SIMS) zircon U-Pb dating gives consistent ages of 230-224 Ma for these rocks, suggesting that they are coeval. All alkaline rocks in the Saima complex are enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depleted in high field strength elements (HFSEs) with significant negative Nb, Ta and Ti anomalies. Geochemical data and Sr-Nd-Hf isotopic compositions indicate that the various alkaline rocks were all derived from partial melting of an ancient, re-enriched lithospheric mantle in the garnet stability field, but experienced variable siliceous- or carbonate-rich crustal contamination. Based on petrographic evidence, mineral compositions, and whole-rock geochemical data, two distinct magmatic evolutionary trends are proposed to explain the coeval emplacement of the various rock types within the Saima alkaline complex. The silica-undersaturated rocks (nepheline syenites and phonolites) result from alkali feldspar + apatite + titanite crystal fractionation of an alkaline mafic parental melt combined with assimilation of marine carbonate host rocks. In contrast, the generation of silica-saturated rocks (quartz-bearing syenites and trachytes) may be attributed to subsequent and continued clinopyroxene + apatite + biotite crystal fractionation coupled with assimilation of siliceous sediments.

  18. Synthesis of main group, rare-earth, and d{sup 0} metal complexes containing beta-hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ka King [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    A series of organometallic compounds containing the tris(dimethylsilyl)methyl ligand are described. The potassium carbanions KC(SiHMe2)3 and KC(SiHMe2})3TMEDA are synthesized by deprotonation of the hydrocarbon HC(SiHMe2)3 with potassium benzyl. KC(SiHMe2)3TMEDA crystallizes as a dimer with two types of three-center-two-electron KH- Si interactions. Homoleptic Ln(III) tris(silylalkyl) complexes containing β-SiH groups M{C(SiHMe2)3}3 (Ln = Y, Lu, La) are synthesized from salt elimination of the corresponding lanthanide halide and 3 equiv. of KC(SiHMe2)3. The related reactions with Sc yield bis(silylalkyl) ate-complexes containing either LiCl or KCl. The divalent calcium and ytterbium compounds M{C(SiHMe2)3}2L (M = Ca, Yb; L = THF2 or TMEDA) are prepared from MI2 and 2 equiv of KC(SiHMe2)3. The compounds M{C(SiHMe2)3}2L (M = Ca, Yb; L = THF2 or TMEDA) and La{C(SiHMe2)3}3 react with 1 equiv of B(C6F5)3 to give 1,3- disilacyclobutane {Me2Si-C(SiHMe2)2}2 and MC(SiHMe2)3HB(C6F5)3L, and La{C(SiHMe2)3}2HB(C6F5)3, respectively. The corresponding reactions of Ln{C(SiHMe2)3}3 (Ln = Y, Lu) give the β-SiH abstraction product [{(Me2HSi)3C}2LnC(SiHMe2)2SiMe2][HB(C6F5)3] (Ln = Y, Lu), but the silene remains associated with the Y or Lu center. The abstraction reactions of M{C(SiHMe2)3}2L (M = Ca, Yb; L = THF2or TMEDA) and Ln{C(SiHMe2)3}3 (Ln = Y, Lu, La) and 2 equiv of B(C6

  19. Spectroscopic characterization of manganese-doped alkaline earth lead zinc phosphate glasses

    Indian Academy of Sciences (India)

    S Sreehari Sastry; B Rupa Venkateswara Rao

    2015-04-01

    Alkaline earth lead zinc phosphate glasses doped with Mn(II) are characterized by spectroscopic techniques like X-ray diffraction (XRD), UV–visible, differential scanning calorimetry (DSC), electron paramagnetic resonance (EPR), Fourier transform infrared (FTIR) and Raman. Optical absorption spectrum exhibits four bands which are characteristic of Mn(II) in distorted octahedral site symmetry. The crystal field parameter Dq and Racah interelectronic-repulsion parameters and have been evaluated. All investigated samples exhibit EPR signals which are characteristic to the Mn2+ ions. The shapes of spectra are also changed with varying alkaline earth ions content. FTIR spectra show specific vibrations of phosphate units. The characteristic Raman bands of these glasses due to stretching and bending vibrations were identified and analysed by varying alkaline earth content. The intensity and frequency variations for the characteristic phosphate group vibrations have been correlated with the changes of the structural units present in these glasses. Depolymerization of the phosphate chains in all the glasses is observed with replacement of alkaline earth content by spectroscopic studies. This leads to a strong decrease of the average chain length and a small decrease of the average P–O–P bridging angle with replacement of alkaline earth content.

  20. Iron complex-catalyzed ammonia-borane dehydrogenation. A potential route toward B-N-containing polymer motifs using earth-abundant metal catalysts.

    Science.gov (United States)

    Baker, R Tom; Gordon, John C; Hamilton, Charles W; Henson, Neil J; Lin, Po-Heng; Maguire, Steven; Murugesu, Muralee; Scott, Brian L; Smythe, Nathan C

    2012-03-28

    Ammonia-borane (NH(3)BH(3), AB) has garnered interest as a hydrogen storage material due to its high weight percent hydrogen content and ease of H(2) release relative to metal hydrides. As a consequence of dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability to control this process and dictate the identity of the generated polymer opens up the possibility of the targeted synthesis of new materials. While precious metals have been used in this regard, the ability to construct such materials using earth-abundant metals such as Fe presents a more economical approach. Four Fe complexes containing amido and phosphine supporting ligands were synthesized, and their reactivity with AB was examined. Three-coordinate Fe(PCy(3))[N(SiMe(3))(2)](2) (1) and four-coordinate Fe(DEPE)[N(SiMe(3))(2)](2) (2) yield a mixture of (NH(2)BH(2))(n) and (NHBH)(n) products with up to 1.7 equiv of H(2) released per AB but cannot be recycled (DEPE = 1,2-bis(diethylphosphino)ethane). In contrast, Fe supported by a bidentate P-N ligand (4) can be used in a second cycle to afford a similar product mixture. Intriguingly, the symmetric analogue of 4 (Fe(N-N)(P-P), 3), only generates (NH(2)BH(2))(n) and does so in minutes at room temperature. This marked difference in reactivity may be the result of the chemistry of Fe(II) vs Fe(0). PMID:22428955

  1. Antihuman Immunodeficiency Virus Type 1 (HIV-1 Activity of Rare Earth Metal Complexes of 4-Hydroxycoumarins in Cell Culture

    Directory of Open Access Journals (Sweden)

    Radka Argirova

    2006-02-01

    Full Text Available The cerium Ce(III, lanthanum La(III, and neodymium Nd(III complexes with 4-hydroxy-3-(3-oxo-1-phenylbutyl-2H-1-benzopyran-2-one (warfarin (W and 3,3′-benzylidenebis[4-hydroxycoumarin] (1 were synthesized and studied for the first time for cytotoxicity (on MT-2 cells and as anti-HIV agents under acute and chronic infection. The complexes were characterized by different physicochemical methods: mass spectrometry, ¹H NMR, ¹³C NMR, and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligands. Anti-HIV effect of the complexes/ligands was measured in MT-2 cells by microtiter infection assay. Detection of endogenous reverse transcriptase (RT activity and RT processivity by PCR indicative for proviral DNA synthesis demonstrated that anti-HIV activity has not been linked to early stages of viral replication. No effect on late steps of viral replication has been found using cells chronically producing HIV-1LAI virus. La(W demonstrated anti-HIV activity (IC50=21.4μM close to maximal nontoxic concentration. Nd(W, Ce(1, and Nd(1 demonstrated limited anti-HIV potency, so none of the complexes seems appropriate to be used in clinic. Further targeting of HIV-1 inhibition by La(W is under progress.

  2. The rare-metal ore potential of the Proterozoic alkaline ultramafic massifs from eastern part of the Baltic Shield in the Kola alkaline province.

    Science.gov (United States)

    Sorokhtina, Natalia; Kogarko, Lia

    2014-05-01

    The Kola Alkaline Province consists of intrusions of two main stages of the intraplate alkaline magmatism. The early stage of igneous activity occurred in Proterozoic 1.9 billion years ago, the next in Paleozoic at 380 million years. The Proterozoic alkaline magmatism produced Gremyakha-Vyrmes and Elet'ozero large alkaline-ultrabasic massifs, Tiksheozero carbonatite massif and numerous small syenite complexes. Paleozoic magmatism on Baltic Shield exhibited more widely, than Proterozoic. The world largest Khibiny and Lovozero alkaline intrusions, numerous alkaline-ultrabasic massifs with carbonanites, alkaline dike swarms and diatremes were formed. It is well known that carbonatites of Paleozoic alkaline-ultrabasic massifs contain large-scale deposits of rare-metal ores (Afanasiev et al., 1998). The metasomatic rocks on foidolites and carbonatites of Gremyakha-Vyrmes are final products of differentiation of Proterozoic alkaline-ultrabasic magma enriched in incompatible elements, including Nb and Zr similar to Paleozoic carbonatites. The massif Gremyakha-Vyrmes is one of the largest titanomagnetite-ilmenite deposits in Russia associated with ultrabasites. Our investigation showed that albite-microcline and aegirine-albite metasomatites formed rich rare-metal ores consisting of 3.2 wt. % Nb2O5 and 0.7 ZrO2. Zircon and pyrochlore-group minerals represent the main minerals of rare-metal ores. The following evolutionary sequences of pyrochlore group minerals has been observed: betafite or U pyrochlore - Na-Ca pyrochlore - Ba-Sr pyrochlore - "silicified" pyrochlore - Fe-Nb, Al-Nb silicates. Such evolution from primary Nb oxides to secondary silicates under low temperature hydrothermal conditions is similar to the evolution of rare metal phases in Paleozoic alkaline massifs analogous to Lovozero syenites and in carbonatites. The rare metal minerals of Gremyakha-Vyrmes crystallized in high alkaline hydrothermal environment at increased activity of Nb, Ta, Zr, U, Th and at

  3. Metal ion complexation by ionizable crown ethers: Progress report, January 1, 1985-December 31, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1987-06-01

    A variety of lipophilic crown ethers with pendant ionizable groups has been prepared. Several lipophilic acyclic polyethers bearing either one or two ionizable groups have also been synthesized. Complexation of alkali metal and alkaline earth cations by such novel ligands has been probed using NMR and solvent extraction. Effects of ring size, side arm length, ionizable group identity and other structural variations, as well as the effect of the solvent, the competitive alkali metal cation solvent extraction has been assessed. Investigations of heavy metal and transition metal cation complexation by ionizable crown ethers have been conducted. The influence of structural variations within acyclic polyether carboxylic acids and dicarboxylic acids on the alkali metal and alkaline earth cation solvent extraction has also been probed. New ligands have been developed which exhibit high selectivities for Cs/sup +/ and Ra/sup 2 +/ in solvent extraction processes. The ability of ionizable crown ethers to function as selective metal cation carriers in liquid membrane transport processes has been examined in both bulk liquid membrane and polymer-supported liquid membrane transport systems.

  4. Carbon nitride nanotube as a sensor for alkali and alkaline earth cations

    International Nuclear Information System (INIS)

    Highlights: ► Adsorption of alkali and alkaline earth cations on a CN nanotube studied by DFT. ► The alkaline cation adsorption may raise potential barrier of the electron emission. ► The tube may act as a sensor in the presence of alkali and alkaline cations. - Abstract: Adsorption of several alkali (Li+, Na+, and K+) and alkaline earth (Be2+, Mg2+, and Ca2+) cations on the surface of a zigzag (9, 0) carbon nitride nanotube has been investigated using density functional theory. It has been found that almost all of the cations prefer to be strongly chemisorbed at the center of porous site of the tube surface. The adsorption of alkaline cations much more influences the electronic properties of the tube, in comparison with the alkali ones, so that it is transformed from an intrinsic semiconductor with HOMO/LUMO energy gap of 4.02 eV to extrinsic p-type one with the gap of 0.54–1.94 eV. The alkaline cation adsorption may significantly raise potential barrier of the electron emission from the tube surface, hence impeding the field emission. It has been also concluded that the electrical sensitivity of the tube toward the cations may be in the order: Be2+ ≫ Mg2+ ≫ Ca2+ ≫ Li+ ∼ Na+ ∼ K+.

  5. Depolarizing collisions with hydrogen: neutral and singly ionized alkaline earths

    CERN Document Server

    Sainz, Rafael Manso; Sanz-Sanz, Cristina; Aguado, Alfredo; Ramos, Andres Asensio; Bueno, Javier Trujillo

    2014-01-01

    Depolarizing collisions are elastic or quasielastic collisions that equalize the populations and destroy the coherence between the magnetic sublevels of atomic levels. In astrophysical plasmas, the main depolarizing collider is neutral hydrogen. We consider depolarizing rates on the lowest levels of neutral and singly ionized alkaly-earths Mg I, Sr I, Ba I, Mg II, Ca II, and Ba II, due to collisions with H. We compute ab initio potential curves of the atom-H system and solve the quantum mechanical dynamics. From the scattering amplitudes we calculate the depolarizing rates for Maxwellian distributions of colliders at temperatures T <10000 K. A comparative analysis of our results and previous calculations in the literature is done. We discuss the effect of these rates on the formation of scattering polarization patterns of resonant lines of alkali-earths in the solar atmosphere, and their effect on Hanle effect diagnostics of solar magnetic fields.

  6. From Metal String Complexes to Metal Wires

    Institute of Scientific and Technical Information of China (English)

    PENG; SheMing

    2001-01-01

    Our efforts to extend the metal number from dinuclear metal complexes to linear oligonuclear metal complexes with all-syn form of oligo-( α-pyridyl)amido ligands are successful. The oligonuclear complexes are divided into two systems according their MM bond strength, one is the oligonickel( Ⅱ ) complexes without M-M bond, the other is the oligochromium(Ⅱ) and cobalt(H) complexes with a strong M-M bond. Their structures and magnetic behaviors for various metal complexes with specific metal numbers are summarized. The potential application of these metal complexes as a molecular metal wire is discussed by the band structures of hypothetical onedinensional metal strings based on the polynuclear Cr, Co and Ni complexes. Moreover, self-assembled monolayers of n-alkanethiols are employed as a two-dinensional matrix to isolate the metal string complexes, which exhibit protrusions under the measurements of scanning tunneling microscopy (STM) imaging. The topographic STM images reveal that the protruding features for tricobalt and trichromium complexes are, respectively, 0.3 nm and 0.6 nm higher than that of trinickel complex. The increasing trend in conductivity is consistent with their bond orders, obtained from qualitative EHMO calculations.  ……

  7. From Metal String Complexes to Metal Wires

    Institute of Scientific and Technical Information of China (English)

    PENG SheMing

    2001-01-01

    @@ Our efforts to extend the metal number from dinuclear metal complexes to linear oligonuclear metal complexes with all-syn form of oligo-( α-pyridyl)amido ligands are successful. The oligonuclear complexes are divided into two systems according their MM bond strength, one is the oligonickel( Ⅱ ) complexes without M-M bond, the other is the oligochromium(Ⅱ) and cobalt(H) complexes with a strong M-M bond. Their structures and magnetic behaviors for various metal complexes with specific metal numbers are summarized. The potential application of these metal complexes as a molecular metal wire is discussed by the band structures of hypothetical onedinensional metal strings based on the polynuclear Cr, Co and Ni complexes. Moreover, self-assembled monolayers of n-alkanethiols are employed as a two-dinensional matrix to isolate the metal string complexes, which exhibit protrusions under the measurements of scanning tunneling microscopy (STM) imaging. The topographic STM images reveal that the protruding features for tricobalt and trichromium complexes are, respectively, 0.3 nm and 0.6 nm higher than that of trinickel complex. The increasing trend in conductivity is consistent with their bond orders, obtained from qualitative EHMO calculations.

  8. Non-covalent (iso)guanosine-based ionophores for alkali(ne earth) cations

    NARCIS (Netherlands)

    Leeuwen, van Fijs W.B.; Davis, Jeffery T.; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    Different (iso)guanosine-based self-assembled ionophores give distinctly different results in extraction experiments with alkali(ne earth) cations. A lipophilic guanosine derivative gives good extraction results for K+, Rb+, Ca2+, Sr2+, and Ba2+ and in competition experiments it clearly favors the d

  9. A study of new rare-earth metal group-13 chalcohalides. Structures, chemistry, and optical properties

    International Nuclear Information System (INIS)

    Full text: Several new quaternary compounds from the rare-earth metal group-13 chalcohalide family have been prepared from alkaline earth halide flux reactions of binary and elemental starting materials. One compound, for example, Ca2La6Ga2S14 , crystallizes as needles in an hexagonal cell while another, more disordered structure, La11Ga19Cl6S42 , crystallizes as monoclinic plates. The former is a condensed structure with channels that contain the alkaline earth element while the latter forms a layered structure containing rare-earth halide clusters within interlayer galleries. These compounds are new members of a family of rare-earth metal main-group chalcogenides which show promise as electroluminescent materials. Structural and spectroscopic studies of these and related compounds will be discussed

  10. Structure of hydrated complexes formed by metal ions of groups I-III of the Periodic table in aqueous electrolyte solutions under ambient conditions

    International Nuclear Information System (INIS)

    Published and authors' experimental data on the structure of aqueous electrolyte solutions under standard conditions were generalized to ascertain the dependences of the solution structural parameters on chemical nature of dissolved compounds of alkali, alkaline-earth metals, cadmium, scandium, yttrium, lanthanum and indium. Hydrate complexes of metal ions formed in aqueous solutions were systematized, depending on cation size, charge and structure of their external electronic shell

  11. Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2

    Science.gov (United States)

    Woollam, J. A.; Somoano, R. B.

    1976-01-01

    Results are reported for measurements of the critical-field anisotropy and temperature dependence of group-VIB semiconductor MoS2 intercalated with the alkali and alkaline-earth metals Na, K, Rb, Cs, and Sr. The temperature dependences are compared with present theories on the relation between critical field and transition temperature in the clean and dirty limits over the reduced-temperature range from 1 to 0.1. The critical-field anisotropy data are compared with predictions based on coupled-layers and thin-film ('independent-layers') models. It is found that the critical-field boundaries are steep in all cases, that the fields are greater than theoretical predictions at low temperatures, and that an unusual positive curvature in the temperature dependence appears which may be related to the high anisotropy of the layer structure. The results show that materials with the largest ionic intercalate atom diameters and hexagonal structures (K, Rb, and Cs compounds) have the highest critical temperatures, critical fields, and critical-boundary slopes; the critical fields of these materials are observed to exceed the paramagnetic limiting fields.

  12. Ion chromatography of transition metals: specific alteration of retention by complexation reactions in the mobile and on the stationary phase

    International Nuclear Information System (INIS)

    Ion chromatography of mono- and bivalent cations was performed on a conventional cation exchanger. The pH influence of an ethylene-diamine/citrate eluent was significant for the retention of alkaline earth and transition metals, but negligible for alkali ions. This was dealt with from a mechanistic point of view. Mobile phase optimization allowed fast isocratic analysis of mono- and bivalent cations and the separation of the radionuclides Cs-137 and Sr-90. A newly synthesized stationary phase containing iminodiacetate (IDA) function was investigated for cation chromatography using ethylenediamine/citrate eluents, polyhydroxy acid and dipicolinic acid. The column's high selectivity for transition metal ions in comparison to alkali and alkaline earth metals may be governed by the choice of complexing ability and pH of the eluent. Applications verified by atomic absorption spectroscopy include alkaline earth metals in beverages and the determination of Co, Cd and Zn in solutions containing more than 1014-fold excess of Na and Mg, such as sea water

  13. Carbon nitride nanotube as a sensor for alkali and alkaline earth cations

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtian, Javad [Department of Chemistry, Shahid Rajaee Teacher Training University, P.O. Box: 16875-163, Tehran (Iran, Islamic Republic of); Baei, Mohammad T. [Department of Chemistry, Azadshahr Branch, Islamic Azad University, Azadshahr, Golestan (Iran, Islamic Republic of); Bagheri, Zargham [Physics Group, Science Department, Islamic Azad University, Islamshahr Branch, P.O. Box: 33135-369, Islamshahr, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi, E-mail: ahmadi.iau@gmail.com [Young Researchers Club, Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Adsorption of alkali and alkaline earth cations on a CN nanotube studied by DFT. Black-Right-Pointing-Pointer The alkaline cation adsorption may raise potential barrier of the electron emission. Black-Right-Pointing-Pointer The tube may act as a sensor in the presence of alkali and alkaline cations. - Abstract: Adsorption of several alkali (Li{sup +}, Na{sup +}, and K{sup +}) and alkaline earth (Be{sup 2+}, Mg{sup 2+}, and Ca{sup 2+}) cations on the surface of a zigzag (9, 0) carbon nitride nanotube has been investigated using density functional theory. It has been found that almost all of the cations prefer to be strongly chemisorbed at the center of porous site of the tube surface. The adsorption of alkaline cations much more influences the electronic properties of the tube, in comparison with the alkali ones, so that it is transformed from an intrinsic semiconductor with HOMO/LUMO energy gap of 4.02 eV to extrinsic p-type one with the gap of 0.54-1.94 eV. The alkaline cation adsorption may significantly raise potential barrier of the electron emission from the tube surface, hence impeding the field emission. It has been also concluded that the electrical sensitivity of the tube toward the cations may be in the order: Be{sup 2+} Much-Greater-Than Mg{sup 2+} Much-Greater-Than Ca{sup 2+} Much-Greater-Than Li{sup +} {approx} Na{sup +} {approx} K{sup +}.

  14. Correlates of long-term alkaline earth retention

    International Nuclear Information System (INIS)

    Data on 63 subjects from several occupational cohorts, plus iatrogenic subjects, were analyzed to determine effects of sex, age at exposure, exposure duration, and age at measurement upon the coefficient of elimination (λ, % y-1). While 12 women exposed at age 17-18 had λ's significantly lower than those exposed at ages 15-16 or 21-26, λ showed no overall trend with age at exposure among females. Higher radium burdens associated with bone damage are associated with decreased λ's, but neither exposure duration nor age at measurement correlated significantly with λ. The 12 males had λ's about 60% of those for females after adjustment for retention time. The males λ's were lower the earlier the age at exposure. Effects of personal habits were studied in a homogeneous cohort of female Illinois dial painters with relatively uniform ages at first employment. The most powerful predictor of radium loss was the number of cups of coffee and tea consumed per day. Coffee/tea consumption explained ∼ 35% of the variance in λ, the effect persisting after deletion of smokers and subjects with x-ray evidence of bone damage. Higher weight/height ratios were associated with higher λ's. Individuals smoking throughout the measurement period had significantly low λ's. A complex interaction of weight/height ratios to both smoking and radium-induced bone damage was observed

  15. Glass-ceramics of alkaline earth chloroaptites as matrices for nuclear waste immobilization

    International Nuclear Information System (INIS)

    Pyrochemical reprocessing is the best suited process for irradiated metallic fuel. Molten salt electro-refining is the most important step to remove U and Pu from the spent metallic fuel by this process. After the electro-refining process the radioactive waste (chloride salts) need to be disposed of in suitable matrices. The current process to treat the chloride waste is to incorporate it in glass-bonded sodalites. In the present study, attempts are made to develop a suitable matrix to immobilize chloride wastes with simple and relatively low temperature processes. Apatites are naturally occurring minerals with a general formula of M10(PO4)6X2, (M= Ca, Sr, Ba; X= OH,CI,F) with a hexagonal crystal structure (S.G : P63/m). Apatites can accommodate alkaline earth and various other aliovalent cations (rare earth etc.) into its crystal structure along with Cl. Apatites are also known to have high resistance to leaching of the constituent elements under geological conditions. It may not be possible to immobilize the whole spectrum of the pyrochemical waste in a single phase M10(PO4)6Cl2, M=Ca, Sr, Ba. However, M-chloroapatite encapsulated in borosilicate glass (BSG) can immobilize most of the radwaste elements in the composite matrix (glass bonded chloroapatite), thus utilizing the immobilizing efficiency of both the ceramic phase and BSG. The apatite glass-ceramics were prepared by mixing and heat-treating stoichiometric concentrations of apatite forming reagents, 20 wt. % borosilicate glass (BSG), and known concentrations (10-15 wt %) of simulated chloride wastes. The mixture of reactants was heated in a platinum crucible at 1023 K for 5h in air. The powders were characterized by XRD to confirm the formation of M10(PO4)6Cl2 (abbreviated to MApCI, M=Ca,Sr,Ba) and glass bonded chloroapatite composites. The surface morphology and qualitative chemical composition of the powders were examined by SEM and EDX. Thermal expansion and glass transition temperature of the matrices

  16. Alkaline earth alkyl insertion chemistry of in situ generated aminoboranes.

    Science.gov (United States)

    Bellham, Peter; Hill, Michael S; Kociok-Köhn, Gabriele; Liptrot, David J

    2013-01-21

    Reactions of equimolar quantities of secondary amine boranes, R(2)NH·BH(3), with the homoleptic group 2 alkyl compounds [M{CH(SiMe(3))(2)}(2)(THF)(2)] (M = Mg, Ca, Sr) provide the alkyl group 2 amido borane derivatives [M{CH(SiMe(3))(2)}{NR(2)BH(3)}(THF)](2). While the strontium derivatives of reactions with dimethylamine and pyrrolidine borane are stable and isolable compounds, the analogous magnesium and calcium compounds are found to be unstable at room temperature. Studies of the thermolysis of the alkylstrontium derivatives have allowed this instability to be rationalised as a result of β-hydride elimination, the facility of which varies with changing M(2+) charge density, to form the products of M-C insertion of H(2)B=NR(2). Subsequent to this process, alkylaminoboranes, [HB(NR(2)){CH(SiMe(3))(2)}], are observed to form through a further suggested β-hydride elimination reaction. This chemistry is also extended to the reaction of the primary amine borane (t)BuNH(2)·BH(3) with [Sr{CH(SiMe(3))(2)}(2)(THF)(2)]. In this case the crystal structure of a heteroleptic species, which may be considered as a tetrameric aggregate of two [Sr{CH(SiMe(3))(2)}{(NH(t)Bu)BH(3)}(2)] anions and two cationic [Sr{(NH(t)Bu)(BH(3))}(THF)(2)] components, has been determined. Kinetic studies of the reactions of [M{CH(SiMe(3))(2)}(2)(THF)(2)] (M = Mg, Ca, Sr) with dimethylamine borane have also been undertaken and describe a complex mechanism in which the barriers to formation of the various intermediate species are a consequence of M(2+) radius and resultant charge density as well as the steric demands of the coordinated amidoborane ligands. PMID:23070304

  17. Properties of the triplet metastable states of the alkaline-earth atoms

    CERN Document Server

    Mitroy, J

    2004-01-01

    The static and dynamic properties of the alkaline-earth atoms in their metastable state are computed in a configuration interaction approach with a semi-empirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described.

  18. Removal of phosphorous through roasting of oolitic iron ore with alkaline earth additives

    OpenAIRE

    Ionkov, Krassimir; GAYDARDZHIEV, Stoyan; Bastin, David; de Araujo, Armando Correa; Lacoste, Marine

    2012-01-01

    The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, ...

  19. TL and XRD correlation studies of RE3+ doped alkaline earth sulphate phosphors

    International Nuclear Information System (INIS)

    Alkaline earth sulphate phosphors activated with ambient weight percentage composition of rare earth (RE) ions were prepared from Indian mineral gypsum and from synthesized sulphate compounds. The results of TL studies have been interpreted in terms of defect levels and the results of X-ray diffraction (XRD) studies are considered in terms of possible sites and population of activator ions in the host lattice. The correlation studies reveal some interesting results and they lead to suggest some suitable model. (author). 5 refs., 3 figs

  20. Electrochemical analysis of metal complexes.

    OpenAIRE

    Jong, de, J.

    1987-01-01

    The present study is concerned with the electroanalytical chemistry of complexes of metals with large ligands. The main purpose was to develop quantitative descriptions of the voltammetric current-potential relation of metal complex systems with different diffusion coefficients of the species involved and of the conductometric response of metal/polyelectrolyte systems at various metal-to-ligand ratios. A further goal was to illustrate the theoretical treatments with some experiments on model ...

  1. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    International Nuclear Information System (INIS)

    In this paper spectroscopic investigation of Cu2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds

  2. 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.

  3. Fabrication and characterization of characteristic luminescent alkali/alkaline earth fluoro boro phosphate glass ceramic materials with some transition metal ions as nucleating agents for the applications in radiation dosimetry

    International Nuclear Information System (INIS)

    The objective of the project is to synthesize CaF2/LiF-B2O3-P2O5 glass materials doped with some transition metal oxides and to study their thermoluminescence (TL) characteristics over a broad range of dose after the characterization of the samples by conventional XRD, SEM techniques and structural analysis of the samples by spectroscopic (IR, optical absorption and ESR) studies. The objectives are further extended to analyze the results of TL in the light of different oxidation states of dopant ions, the dose of ionizing radiation and the topology of the glass network and to comment on suitability of the materials for TL dosimetry

  4. Electrochemical analysis of metal complexes.

    NARCIS (Netherlands)

    Jong, de H.G.

    1987-01-01

    The present study is concerned with the electroanalytical chemistry of complexes of metals with large ligands. The main purpose was to develop quantitative descriptions of the voltammetric current-potential relation of metal complex systems with different diffusion coefficients of the species involv

  5. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    International Nuclear Information System (INIS)

    Defects in Ce3+- and Eu2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF2:Eu2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF2:Ce3+ and SrF2:Ce3+ crystals. Creation of Ce2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce2+ or Eu+ ions

  6. Valence of 'divalent' rare earth metals

    International Nuclear Information System (INIS)

    It is generally recognized that light rare earths change their valence from 2 to 3 when forming a bulk metal while remaining divalent at the surface. However, performed DFT calculations ultimately indicate that the higher-binding-energy peaks in photoemission spectra (like the -5.3 eV peak for Sm), characteristic of the trivalent 4fn-15d1 configuration, correspond not to the ground state, but to excited states induced by radiation. This means that the trivalent state is not inherent for the bulk of divalent rare earths, and therefore they do not become trivalent.

  7. Hydrogen storage of a novel combined system of LiNH2-NaMgH3: synergistic effects of in situ formed alkali and alkaline-earth metal hydrides.

    Science.gov (United States)

    Li, Yongtao; Fang, Fang; Song, Yun; Li, Yuesheng; Sun, Dalin; Zheng, Shiyou; Bendersky, Leonid A; Zhang, Qingan; Ouyang, Liuzhang; Zhu, Min

    2013-02-01

    Bimetallic hydride NaMgH(3) is used for the first time as a vehicle to enhance hydrogen release and uptake from LiNH(2). The combination of NaMgH(3) with LiNH(2) at a molar ratio of 1 : 2 can release about 4.0 wt% of hydrogen without detectable NH(3) emission in the temperature range of 45 °C to 325 °C and exhibiting superior dehydrogenation as compared to individual NaH and/or MgH(2) combined with LiNH(2). A high capacity retention of about 75% resulting from the introduction of NaMgH(3) is also achieved in LiNH(2) as well as re-hydrogenation under milder conditions of 180 °C and 5 MPa H(2) pressure. These significant improvements are attributed to synergistic effects of in situ formed NaH and MgH(2)via the decomposition of NaMgH(3) where a succession of competing reactions from the cyclic consumption/recovery of NaH are involved and serve as a "carrier" for the ultra-rapid conveyance of the N-containing species between the [NH(2)](-) amide and the resulting [NH](2-) imide complexes. PMID:23165760

  8. Optical Algal Biosensor using Alkaline Phosphatase for Determination of Heavy Metals

    OpenAIRE

    Durrieu, Claude; Tran-Minh, Canh

    2002-01-01

    International audience A biosensor is constructed to detect heavy metals from inhibition of alkaline phosphatase (AP) present on the external membrane of Chlorella vulgaris microalgae. The microalgal cells are immobilized on removable membranes placed in front of the tip of an optical fiber bundle inside a homemade microcell. C. vulgaris was cultivated in the laboratory and its alkaline phosphatase activity is strongly inhibited in the presence of heavy metals. This property has been used ...

  9. Electronic structures, mechanical and thermodynamic properties of cubic alkaline-earth hexaborides from first principles calculations

    International Nuclear Information System (INIS)

    Highlights: • The band gaps for CaB6, SrB6 and BaB6 depend sensitively on the values of lattice constant a and positional parameter z. • The order in elastic anisotropy is CaB6 > SrB6 > BaB6. • There are LO/TO splitting lines in the range of 5–10 THz at G point. - Abstract: The electronic structures, mechanical and thermodynamic properties of alkaline-earth hexaborides MB6 (M = Ca, Sr or Ba) are calculated from first principles using density functional theory combined with the quasi-harmonic approximation. These three alkaline-earth hexaborides are semiconductors with a slightly increased trend for their band gaps as M orders from Ca to Ba. Their band gaps depend sensitively on the values of lattice constant a and internal parameter z. The polycrystalline values of the elastic constants and bulk, shear and Young’s moduli are consistent with those determined experimentally. All alkaline-earth hexaborides have strongly anisotropic elastic properties in the order of CaB6 > SrB6 > BaB6. By using the phonon calculations, the thermodynamic properties are investigated. The obtained phonon dispersion relations for CaB6, SrB6, and BaB6 show similar features and there are LO/TO splitting lines in the range of 5–10 THz. Finally, the thermal conductivities of CaB6, SrB6 and BaB6 are evaluated via Clarke’s model and Cahill’s model

  10. Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1994-12-31

    During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.

  11. Comparison of Ce$^{3+}$ and Pr$^{3+}$ activators in alkaline-earth fluoride crystals

    OpenAIRE

    Radzhabov, E.; Nepomnyaschikh, A.

    2012-01-01

    The emission spectra of Ce$^{3+}$ or Pr$^{3+}$ doped CaF$_2$, SrF$_2$, BaF$_2$ excited by vacuum ultraviolet photons or by x-ray as well as excitation and absorption spectra in vacuum ultraviolet region (6-13 eV) were studied. The transfer of exciton energy is the main channel for Ce$^{3+}$ excitation in alkaline-earth fluorides. Three different stages of energy transfer were observed. Pr$^{3+}$ excited by two processes, slow f-f luminescence excited by excitons, fast d-f luminescence excited...

  12. High-Tc thin films on low microwave loss alkaline-rare-earth-aluminate crystals

    International Nuclear Information System (INIS)

    This paper reports on the alkaline-rare-earth aluminates (K2NiF4-type perovskites) which are an excellent choice as the substrate material for the growth of high-Tc thin films suitable for microwave and far-infrared applications. The CaNdAlO4, and SrLaAlO4 single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties

  13. STARK STRUCTURE OF THE RYDBERG STATES OF ALKALINE-EARTH ATOMS

    Institute of Scientific and Technical Information of China (English)

    郅妙婵; 戴长建; 李士本

    2001-01-01

    The Stark effects of the Rydberg states in the alkaline-earth atoms are studied theoretically. Using a method similar to the treatment of alkali atoms, the properties of the Stark states of Mg, Ca, Sr and Ba atoms in the regions far away from the perturbers are investigated. The Stark maps for Mg (n=16, M=0), Ca (n=10, M=0), Sr (n=12,M=0) and Ba (n=13, |M|=0,1) are presented. Topics such as the general methods of calculation, the treatment of fine structure, and the structure of level anti-crossings are discussed. The comparison between the theoretical and experimental Stark maps is satisfactory.

  14. Environmental effects on fatigue of alkaline earth aluminosilicate glass with varying fictive temperature

    DEFF Research Database (Denmark)

    Striepe, Simon; Deubener, Joachim; Smedskjær, Morten Mattrup; Potuzak, Marcel

    2013-01-01

    The influence of relative humidity on microhardness, stress intensity, crack resistance, and sub-critical crack growth of an alkaline earth aluminosilicate glass has been studied by Vickers indentation. Quenched and annealed glasses with a wide range of fictive temperatures (ΔTf ≈ 130 K) are....... The glasses with lower fictive temperature exhibit a larger change in the micromechanical properties when comparing wet and dry conditions. Finally, it is found that sub-critical crack growth is larger in the low fictive temperature glasses, indicating a diminished resistance against fatigue and...

  15. 与碳酸岩-碱性杂岩体相关的内生稀土矿床成矿作用研究进展%Review of the Metallogenesis of the Endogenetic Rare Earth Elements Deposits Related to Carbonatite-Alkaline Complex

    Institute of Scientific and Technical Information of China (English)

    宋文磊; 许成; 王林均; 吴敏; 曾亮; 王丽泽; 冯梦

    2013-01-01

    The geological characteristics and mineralization of the endogenetic rare earth elements (REE) deposits related with carbonatite-alkaline complexes are reviewed.The REE deposits mainly include primary magmatic and hydrothermal types.The former is relatively rare,and REE minerals crystallized from carbonatite magma.The REE minerals in hydrothermal deposits are intergrowth with calcite,fluorite,barite,quartz.They occur as ore veins intruding carbonatite-alkaline complexes and wall rocks,or as fracture or void filling fine-grained,polycrystalline aggregates overprinting earlier carbonatitic minerals.Previous researches showed that REE mineralization was controlled by the crystallization and accumulation of carbonate minerals during carbonatitc magma-hydrothermal processes.However,REE enrichment mechanism is still debate,i.e.liquid immiscibility of carbonate-silicate magmas,fractional crystallization of carbonate minerals from carbonatite magma,extraction of carbonatitic liquids,and hydrothermal alteration of carbonatites.Note carbonatites normally show light REE enrichment and mineralization,and absent heavy REE minerals.Therefore,high temperature and pressure experiments on REE partition coefficients between volatile-rich carbonate and alkaline silicate melts or fluids,and REE partition behavior between carbonate and co-precipitating minerals during carbonatite magma evolution,will be a key to reveal the REE mineralization mechanism.%综述与碳酸岩-碱性杂岩体相关的内生稀土矿床的基本特征和成矿作用研究进展.根据矿化特征,该类矿床大体可以分为原生岩浆型和热液型,前者稀土矿物是从碳酸岩岩浆中直接结晶出来,矿化主要产于碳酸岩岩体中;后者稀土矿物通常与方解石、萤石、重晶石、石英等矿物共生形成脉体,穿插于碳酸岩杂岩体及围岩中,或作为裂隙或空洞充填物,或呈细粒多晶集合体叠加在碳酸岩中早期形成的矿物之上.以往的研究

  16. Complex metal hydrides

    DEFF Research Database (Denmark)

    Ley, Morten Brix

    2014-01-01

    og batterier de to mest lovende energibærere til mobile applikationer. Komplekse metalhydrider er blevet undersøgt i vid udstrækning over de sidste tyve år, siden de gravimetrisk og volumetrisk kan indeholde store mængder brint. Derfor er metal borhydrider velegnet til faststofopbevaring af brint...

  17. Health Effects of Alkaline Diet and Water, Reduction of Digestive-tract Bacterial Load, and Earthing.

    Science.gov (United States)

    Mousa, Haider Abdul-Lateef

    2016-04-01

    In the article, the author discusses the issue of chronic, low-grade acidosis that is thought to be brought about primarily by 2 factors: (1) advancing age, with a consequent decline in renal function; and (2) diet. An acid-forming diet can induce low-grade metabolic acidosis, which causes very small decreases in blood pH and plasma bicarbonate (HCO3-) that remain within the range considered to be normal. However, if the duration of the acidosis is prolonged or chronically present, even a low degree of acidosis can become significant. This article reviews supporting evidence in the literature that has shown that consumption of abundant alkaline-forming foods can result in improvement in bone mineral density (BMD) and muscle mass, protection from chronic illnesses, reduced tumor-cell invasion and metastasis, and effective excretion of toxins from the body. In addition, a large number of studies showing the benefits of alkaline water (mineral water) have revealed that people consuming water with a high level of total dissolved solids (TDS) (ie, with a high mineral content) have shown a lower incidence of coronary heart disease (CHD), cardiovascular disease (CVD), and cancer and lower total mortality rates. Consumption of alkaline water also may prevent osteoporosis and protect pancreatic beta cells with its antioxidant effects. In addition, this article discusses the literature that shows that reducing digestive-tract bacterial load can play an important role in increasing blood alkalinity toward the normal upper limit. That change occurs through good oral hygiene, flossing of teeth, perfect chewing of food, and bowel evacuation as soon as possible. Finally, the author reviews the literature that shows that earthing (ie, the direct contact of the human body with the earth) can supply a current of plentiful electrons. Earthing has been shown to reduce acute and chronic inflammation, blood glucose in patients with diabetes, red blood cell (RBC) aggregation, and blood

  18. Thermodynamic models of alkaline-earth metal ion flotation

    International Nuclear Information System (INIS)

    Two thermodynamic models for predicting selectivity coefficients for the pairs Be2+/Cu2+, Mg2+/Cu2+, Ca2+/Cu2+, Sr2+/Cu2+, and Ba2+/Cu2+ in ion flotation with the dodecyl sulfate ion as a collector are compared. The dehydration model largely gives exaggerated results, and the cavity model gives both exaggerated and underestimated values compared with the experimental selectivity coefficients. The cavity model was found to better describe molecules and ions of different sizes

  19. Modelling three-dimensional-quench cooling for alkaline-earth atoms

    CERN Document Server

    Mehlstaeubler, T E; Douillet, A; Rehbein, N; Rasel, E M; Ertmer, W

    2003-01-01

    Quench cooling is a promising technique to reach ultra-cold temperatures in alkaline-earth atoms by Doppler cooling on ultra-narrow transitions. The principles of quench cooling are derived from an effective two-level system with a linewidth adjustable by the quenching laser. A tunable linewidth reconciles the contradictory requirements of a fast cooling rate and a high velocity selectivity at high and low temperatures, respectively. In this paper, we investigate the efficiency of quench cooling in alkaline-earth systems. We present a one-dimensional analytical description of the quenching process. Cooling and trapping in three dimensions is studied with semi-classical Monte Carlo simulations. Our results for magnesium indicate a loading efficiency of up to 40% of pre-cooled atoms at 2 mK into a QuenchMOT. Final temperatures of 9 mu K and an increase in phase-space density by almost five orders of magnitude are observed in the simulations.

  20. A 3-photon process for producing degenerate gases of metastable alkaline-earth atoms

    Science.gov (United States)

    Barker, Daniel S.; Pisenti, Neal C.; Reschovsky, Benjamin J.; Campbell, Gretchen K.

    2016-05-01

    We present a method for creating quantum degenerate gases of metastable alkaline-earth atoms. A degenerate gas in any of the 3 P metastable states has not previously been obtained due to large inelastic collision rates, which are unfavorable for evaporative cooling. Samples prepared in the 1S0 ground state can be rapidly transferred to either the 3P2 or 3P0 state via a coherent 3-photon process. Numerical integration of the density matrix evolution for the fine structure of bosonic alkaline-earth atoms shows that transfer efficiencies of ~= 90 % can be achieved with experimentally feasible laser parameters in both Sr and Yb. Importantly, the 3-photon process does not impart momentum to the degenerate gas during excitation, which allows studies of these metastable samples outside the Lamb-Dicke regime. We discuss several experimental challenges to the successful realization of our scheme, including the minimization of differential AC Stark shifts between the four states connected by the 3-photon transition.

  1. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    International Nuclear Information System (INIS)

    Defects in Ce3+- and Eu2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (UV) photons at energies lower than at the bandgap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF2:Eu2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after vacuum UV illumination as after x-irradiation. Thermoluminescence curves of Ce3+-doped alkaline-earth fluorides created by vacuum UV illumination or x-irradiation were generally similar. However, Vk thermoluminescence peaks were absent in vacuum UV illuminated CaF2:Ce3+ and SrF2:Ce3+ crystals. This fact is obviously associated with the presence of charge-compensating fluorine interstitials in Ce3+-doped crystals. The creation of Ce2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum UV illuminated or x-irradiated Ce3+-doped crystals. The suppression of hole thermoluminescence peaks in CaF2:aF2:Eu2+ crystals by blue light is due to the photoionization of Eu+ ions. The proposed mechanism for the creation of trapped hole and trapped-electron defects by vacuum UV illumination involves charge-transfer-type transitions, in which the electron transfers from the valence band to an impurity level lying in the bandgap. Comparison of all energies involved of transitions in the crystals investigated shows that the sum of all the transition energies is less than that of the bandgap by 1.5-3.5 eV. This energy difference can be considered to be the energy of lattice relaxation around the created Ce2+ or Eu+ ions. (author)

  2. Contrasting magmatic signatures in the Rairakhol and Koraput alkaline complexes, Eastern Ghats belt, India

    Indian Academy of Sciences (India)

    S Bhattacharya; M Basei

    2010-04-01

    The relation between alkaline magmatism and tectonism has been a contentious issue, particularly for the Precambrian continental regions. Alkaline complexes at the southwestern margin of Eastern Ghats belt, India, have been interpreted as rift-valley magmatism. However, those complexes occurring in granulite ensemble in the interior segments of the Eastern Ghats belt could not possibly be related to the rift-system, assumed for the western margin of the Eastern Ghats belt. Koraput complex was emplaced in a pull-apart structure, dominated by magmatic fabrics and geochemically similar to a fractionated alkaline complex, compatible with an alkalibasalt series. Rairakhol complex, on the other hand, shows dominantly solid-state deformation fabrics and geochemically similar to a fractionated calc-alkaline suite. Isotopic data for the Koraput complex indicate ca. 917 Ma alkaline magmatism from a depleted mantle source and postcrystalline thermal overprint at ca. 745 Ma, also recorded from sheared metapelitic country rocks. The calc-alkaline magmatism of the Rairakhol complex occurred around 938 Ma, from an enriched mantle source, closely following Grenvillian granulite facies imprint in the charnockitic country rocks.

  3. Water-free Alkaline Polymer-inorganic Acid Complexes with High Conductivity at Ambient Temperature

    Institute of Scientific and Technical Information of China (English)

    O.V.Chervakov; M.V.Andriianova; V.V.Riabenko; A.V.Markevich; E.M.Shembel; D.Meshri

    2007-01-01

    1 Results Recently increased interest is shown to proton conducting materials based on the alkaline polymer-inorganic acid complexes that is caused by a possibility of their application as the high-temperature electrolyte systems for various electrochemical devices (fuel cells,sensors,lithium power sources etc.).Complexes of inorganic acids with the alkaline polymers (polybenzimidazoles[1],polyvinylpyridines[2]) are characterized by high ionic conductivity at ambient temperatures (up to 10-2 Ω-1·cm-1) a...

  4. Influence of radionuclide residence time in soil and of competing alkaline earth elements on radium uptake by edible plants

    International Nuclear Information System (INIS)

    The uptake of Ra by plants and its dependence on the residence time as well as on the concentration of other alkaline earth elements was studied with soil contaminated several decades ago. Only the use of a well weathered Ra containing soil provides a realistic model for transfer factor determinations since the bioavailability of radium bound to soil particles is lower than in freshly prepared mixtures. The plants investigated are: tomatoes, cress, dandelions, radishes and mangold; they were chosen for their different behaviour towards alkaline earth elements, such as calcium. The contents of some elements taken up by the plants, especially the alkaline earths, were determined in their ashes by atomic absorption spectrometry. (orig./HP)

  5. Group 1 and group 2 metal complexes supported by a bidentate bulky iminopyrrolyl ligand: synthesis, structural diversity, and ε-caprolactone polymerization study.

    Science.gov (United States)

    Kottalanka, Ravi K; Harinath, A; Rej, Supriya; Panda, Tarun K

    2015-12-14

    We report here a series of alkali and alkaline earth metal complexes, each with a bulky iminopyrrolyl ligand [2-(Ph3CN=CH)C4H3NH] (1-H) moiety in their coordination sphere, synthesized using either alkane elimination or silylamine elimination methods or the salt metathesis route. The lithium salt of molecular composition [Li(2-(Ph3CN=CH)C4H3N)(THF)2] (2) was prepared using the alkane elimination method, and the silylamine elimination method was used to synthesize the dimeric sodium and tetra-nuclear potassium salts of composition [(2-(Ph3CN=CH)C4H3N)Na(THF)]2 (3) and [(2-(Ph3CN=CH)C4H3N)K(THF)0.5]4 (4) respectively. The magnesium complex of composition [(THF)2Mg(CH2Ph){2-(Ph3CN=CH)C4H3N}] (5) was synthesized through the alkane elimination method, in which [Mg(CH2Ph)2(OEt2)2] was treated with the bulky iminopyrrole ligand 1-H in 1 : 1 molar ratio, whereas the bis(iminopyrrolyl)magnesium complex [(THF)2Mg{2-(Ph3CN=CH)C4H3N}2] (6) was isolated using the salt metathesis route. The heavier alkaline earth metal complexes of the general formula {(THF)nM(2-(Ph3CN=CH)C4H3N)2} [M = Ca (7), Sr (8), and n = 2; M = Ba (9), n = 3] were prepared in pure form using two synthetic methods: in the first method, the bulky iminopyrrole ligand 1-H was directly treated with the alkaline earth metal precursor [M{N(SiMe3)2}2(THF)n] (where M = Ca, Sr and Ba) in 2 : 1 molar ratio in THF solvent at ambient temperature. The complexes 7-9 were also obtained using the salt metathesis reaction, which involves the treatment of the potassium salt (4) with the corresponding metal diiodides MI2 (M = Ca, Sr and Ba) in 2 : 1 molar ratio in THF solvent. The molecular structures of all the metal complexes (1-H, 2-9) in the solid state were established through single-crystal X-ray diffraction analysis. The complexes 5-9 were tested as catalysts for the ring-opening polymerization of ε-caprolactone. High activity was observed in the heavier alkaline earth metal complexes 7-9, with a very

  6. Relations between structure and material properties in earth alkaline silicate basing phosphors; Struktureigenschaftsbeziehungen in Erdalkalisilikat basierenden Leuchtstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Wolfgang

    2008-03-19

    This work is basing on the relation between structure and luminescence of Eu{sup 2+} doped Earth-Alkaline-Silicates. After an overview of Earth-Alkaline-Silicates silicates with an additional cation (Li{sup +}, Al{sup 3+}) and an additional anion (Cl{sup -}, N{sup 3-}) are examined in chapter 4 and 5. Basing on this data an relation between structural influence - like ion-radii, anion and coordination polyeder - and phosphor luminescence is set up. The ability of using as an industrial phosphor is made in the final chapter. (orig.)

  7. Assessing the Effectiveness and Side-Effects of Ocean Alkalinity Enhancement in an Earth System Model

    Science.gov (United States)

    Jones, S. E.; Ridgwell, A. J.

    2013-12-01

    At present, the potential to decrease atmospheric carbon dioxide concentrations by manipulating the carbon cycle (carbon geoengineering) is being considered as a fourth possible option for addressing anthropogenic climate change, alongside emissions reductions, adaptation and solar geoengineering. This study sets out to assess the effectiveness and potential side-effects of ocean alkalinity enhancement, or ';liming the ocean', as a means to slow the current increase in atmospheric CO2. In order to achieve this, an Earth system model (cGENIE) was used to run both individual simulations as well as a number of 934-member ensembles, to assess each surface ocean grid cell individually, for effectiveness and side-effects of ocean alkalinity enhancement. Effectiveness and side-effects were considered both temporally and spatially and under both steady-state scenarios (of 1x, 2x and 4x pre-industrial pCO2), and using RCP scenarios 4.5 and 8.5. Some consideration of the amount of lime potentially required to have a useful impact on atmospheric CO2 concentration and ocean acidification has also been carried out and compared to current mining capabilities, as an initial step towards considering the feasibility of such an intervention. This research aims to inform the emerging debate around geoengineering by providing an initial insight into where, when and how frequently lime could be used to most efficiently contribute to efforts to slow the rate of increasing atmospheric CO2 concentrations, as well as insights into the caveats and side-effects that may accompany ocean alkalinity enhancement interventions.

  8. Impacts of artificial ocean alkalinization on the carbon cycle and climate in Earth system simulations

    Science.gov (United States)

    González, Miriam Ferrer; Ilyina, Tatiana

    2016-06-01

    Using the state-of-the-art emissions-driven Max Planck Institute Earth system model, we explore the impacts of artificial ocean alkalinization (AOA) with a scenario based on the Representative Concentration Pathway (RCP) framework. Addition of 114 Pmol of alkalinity to the surface ocean stabilizes atmospheric CO2 concentration to RCP4.5 levels under RCP8.5 emissions. This scenario removes 940 GtC from the atmosphere and mitigates 1.5 K of global warming within this century. The climate adjusts to the lower CO2 concentration preventing the loss of sea ice and high sea level rise. Seawater pH and the carbonate saturation state (Ω) rise substantially above levels of the current decade. Pronounced differences in regional sensitivities to AOA are projected, with the Arctic Ocean and tropical oceans emerging as hot spots for biogeochemical changes induced by AOA. Thus, the CO2 mitigation potential of AOA comes at a price of an unprecedented ocean biogeochemistry perturbation with unknown ecological consequences.

  9. High resolution spectroscopy of alkaline earth monohalides: perturbation analysis, hyperfine structure and stark effect

    International Nuclear Information System (INIS)

    This paper applies a number of laser spectroscopic methods, some of which have been newly developed, to the group of alkaline earth monohalide radicals. The effects of weak hyperfine interaction were studied by using laser-mw double resonance techniques and the Stark effect was investigated at high resolution in molecular beam experiments. Doppler-free polarization spectroscopy provided the sensitivity and resolution needed for the analysis of optical spectra. In the particulary congested parts of the spectra mw labeling was helpful for the identification of lines. It is to be expected that these methods will be applied to other groups of free radicals in the near future and help to cast some light on the structure of new interesting molecular species

  10. Parity violating radiative emission of neutrino pair in heavy alkaline earth atoms of even isotopes

    CERN Document Server

    Yoshimura, M; Uetake, S

    2014-01-01

    Metastable excited states ${}^3P_2, {}^3P_0$ of heavy alkaline earth atoms of even isotopes are studied for parity violating (PV) effects in radiative emission of neutrino pair (RENP). PV terms arise from interference between two diagrams containing neutrino pair emission of valence spin current and nuclear electroweak charge density proportional to the number of neutrons in nucleus. This mechanism gives large PV effects, since it does not suffer from the suppression of 1/(electron mass) usually present for non-relativistic atomic electrons. A controllable magnetic field is crucial to identify RENP process by measuring PV observables. Results of PV asymmetries under the magnetic field reversal and the photon circular polarization reversal are presented for an example of Yb atom.

  11. Role of elastic deformation in determining the mixed alkaline earth effect of hardness in silicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Potuzak, M.;

    2015-01-01

    show that the mixed alkaline earth effect manifests itself as deviations from linearity in shear modulus, Poisson’s ratio, glass transition temperature, liquid fragility index, hardness, volume of densification, and volume of plastic flow. We find no correlation between the elastic part of the......Glasses deform permanently as a result of indentation and the total resistance to deformation consists of three individual resistances, i.e., those to elastic deformation, densification, and plastic flow. The link between Vickers hardness and the resistances to densification and plastic flow has...... been investigated previously, but the link between the resistance to elastic deformation and hardness has not yet been studied. In this work, we investigate the link between elastic deformation during indentation and Vickers hardness in a series of mixed magnesium-barium boroaluminosilicate glasses. We...

  12. An {\\it ab initio} relativistic coupled-cluster theory of dipole and quadrupole polarizabilities: Applications to a few alkali atoms and alkaline earth ions

    CERN Document Server

    Sahoo, B K

    2006-01-01

    We present a general approach within the relativistic coupled-cluster theory framework to calculate exactly the first order wave functions due to any rank perturbation operators. Using this method, we calculate the static dipole and quadrupole polarizabilities in some alkali atoms and alkaline earth-metal ions. This may be a good test of the present theory for different rank and parity interaction operators. This shows a wide range of applications including precise calculations of both parity and CP violating amplitudes due to rank zero and rank one weak interaction Hamiltonians. We also give contributions from correlation effects and discuss them in terms of lower order many-body perturbation theory.

  13. Raman and Rietveld structural characterization of sintered alkaline earth doped ceria

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Junior, Jose Marcio; Brum Malta, Luiz Fernando; Garrido, Francisco M.S. [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil); Ogasawara, Tsuneharu [Programa de Engenharia Metalurgica e de Materiais, Coordenacao dos Programas de Pos - Graduacao de Engenharia, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CEP 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Medeiros, Marta Eloisa, E-mail: chico@iq.ufrj.br [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil)

    2012-08-15

    Nanocrystalline calcium and strontium singly doped ceria and co-doped ceria materials for solid electrolytes were prepared via a hydrothermal route. The effect of the hydrothermal treatment time on the solid solution composition was evaluated. Sr doped ceria was the most difficult to form, due to the Sr{sup 2+} large ionic radius. The small crystal size (12-16 nm) of powders allowed sintering into dense ceramic pellets at 1350 Degree-Sign C for 5 h. Raman spectroscopy evidenced a great lattice distortion for Sr doped and co-doped ceria materials, explaining the deterioration of the electrical properties for these ceramics. Besides that, a second phase was detected for Sr doped ceria pellet by using X-ray powder diffraction and Rietveld refinement of XRD data. Impedance measurements showed that Ca-doped ceria behaves as the best ionic conductor ({sigma}{sub g} 390 Degree-Sign C = 1.0 Multiplication-Sign 10{sup -3} S cm{sup -1}) since the nominal composition was achieved; on the other hand, Sr doped ceria performed as resistive materials since Sr incorporation into ceria lattice was critical. These results enhance the close interlace between electrical performance and chemical composition of alkaline earth doped ceria. -- Highlights: Black-Right-Pointing-Pointer Hydrothermally synthesized calcium doped ceria nanoparticles. Black-Right-Pointing-Pointer Incorporation of alkaline earth dopant into ceria lattice. Black-Right-Pointing-Pointer Raman and Rietveld structural characterization. Black-Right-Pointing-Pointer Calcium doped ceria ceramic pellets with high ionic conductivity. Black-Right-Pointing-Pointer Problems associated with the Sr{sup 2+} incorporation into ceria lattice.

  14. Long-range interactions of excited He atoms with the alkaline earth atoms Mg, Ca, and Sr

    KAUST Repository

    Zhang, J.-Y.

    2013-04-05

    Dispersion coefficients for the long-range interactions of the first four excited states of He, i.e., He(2 1, 3 S) and He(2 1, 3 P), with the low-lying states of the alkaline earth atoms Mg, Ca, and Sr are calculated by summing over the reduced matrix elements of multipole transition operators.

  15. Studies on the determination of trace amounts of nitrogen along with alkali and alkaline earth elements in uranium based samples by ion-chromatography (IC)

    International Nuclear Information System (INIS)

    Present report describes an ion chromatography (IC) method with suppressed conductivity detection for the determination of traces of nitrogen along with alkali and alkaline earth elements in uranium based nuclear fuels. Method was developed to determine nitrogen as NH4+ along with alkali and alkaline earth cations by IC using a cation exchange column. (author)

  16. Alkaline phosphatase activity in the subtropical ocean: insights from nutrient, dust and trace metal addition experiments

    Directory of Open Access Journals (Sweden)

    Claire eMahaffey

    2014-12-01

    Full Text Available Phosphorus is an essential nutrient for all life on earth. In the ocean, the most bioavailable form of phosphorus is inorganic phosphate, but in the extensive subtropical gyres, phosphate concentrations can be chronically low and limit primary productivity and nitrogen fixation. In these regions, organisms produce hydrolytic enzymes, such as alkaline phosphatase (AP, that enable them to utilize the more replete dissolved organic phosphorus (DOP pool to meet their cellular phosphorus demands. In this study, we synthesized data from 14 published studies and present our own findings from two research cruises (D326 and D361 in the eastern subtropical Atlantic to explore the relationship between AP activity (APA and nutrients, Saharan dust and trace metals. We found that below a threshold phosphate concentration of ~ 30 nM, APA increased with an inverse hyperbolic relationship with phosphate concentration. Meanwhile, DOP concentrations decreased with enhanced APA, indicating utilization of the DOP pool. We found APA rates were significantly higher in the subtropical Atlantic compared to the subtropical Pacific Ocean, even over the same low phosphate concentration range (0 to 50 nM. While the phosphate concentration may have a first order control on the APA rates, we speculate that other factors influence this basin scale contrast. Using bioassay experiments, we show that the addition of Saharan dust and zinc significantly increased the rate of APA. To our knowledge, our results are the first direct field-based evidence that APA is limited by zinc in the subtropical ocean. Further work is required to explore the relationship between trace metals such as iron and zinc, which are co-factors of phosphohydrolytic enzymes, specifically PhoX and PhoA, respectively, and APA in the ocean.

  17. A Density Functional Theory Study of Codoping Characteristics of Sulfur with Alkaline Earth in Delafossite CuAlO2

    Science.gov (United States)

    Qi-Jun, Liu; Han, Qin; Zheng-Tang, Liu

    2016-04-01

    The structural, electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO2 have been investigated using the first-principles density functional theory calculations. Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms. The formation energies under different growth conditions have been calculated, showing that the codoping systems are formed easily under O-rich growth conditions. Electronic band structures and density of states have been obtained. The decreased bandgaps, enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity. Supported by the National Natural Science Foundation of China under Grant Nos. 11347199, 51402244, and 11547311, the Specialized Research Fund for Doctoral Program of Higher Education of China under Grant No. 20130184120028, the Fundamental Research Fund for the Central Universities, China under Grant Nos. 2682014CX084, 2682014ZT30, and 2682014ZT31, and the fund of the State Key Laboratory of Solidification Processing in NWPU under Grant No. SKLSP201511

  18. Study of the effect hydrogen binding in the solvation of alkaline earth cations with MeOH in nitromethane using 1 H NMR technique and determination of ionic solvation number

    CERN Document Server

    Alizadeh, N

    2001-01-01

    A proton NMR method for the study of the effect hydrogen binding and determination of solvation numbers of alkaline earth cations with methanol (MeOH) in in tromethane (NM) as diluent is described. The method is based on monitoring the resonance frequency of MeOH protons as a function of MeOH to metal ion mole ratio at constant metal ion concentration. the average solvation number of cation, n, at any MeOH/ metal ion mole ration was calculated from the NMR chemical shift-mole ration data and was plotted against the mole ration values. The solvation numbers of alkaline earth cations were obtained from the limiting values of the corresponding n, vs. mole ratio plots.

  19. SIMULATION AND OPTIMIZATION OF TIMBER ALKALINE PULPING PROCESS IN PRESENCE OF SALTS OF SOME METALS HAVING MIXED VALENCE

    OpenAIRE

    I. Karpunin

    2012-01-01

    Process of alkaline pulping in the presence of salts of some metals having mixed valence has been simulated on the basis of the executed investigations. The paper reveals that optimization of alkaline (sulphate) pulping depends on chemical nature and metal and its amount which is introduced in the form of salt.

  20. SIMULATION AND OPTIMIZATION OF TIMBER ALKALINE PULPING PROCESS IN PRESENCE OF SALTS OF SOME METALS HAVING MIXED VALENCE

    Directory of Open Access Journals (Sweden)

    I. Karpunin

    2012-01-01

    Full Text Available Process of alkaline pulping in the presence of salts of some metals having mixed valence has been simulated on the basis of the executed investigations. The paper reveals that optimization of alkaline (sulphate pulping depends on chemical nature and metal and its amount which is introduced in the form of salt.

  1. Differential enthalpy of cation exchange of alkaline metals on amorphous zirconium phosphate

    International Nuclear Information System (INIS)

    Work presents the results of calorimetric research of sorption process of alkaline metals cations on hydrogen form of amorphous zirconium phosphates. It is defined that the general regularities of passing of ion exchange reaction are the same for the samples of zirconium phosphate with different content of phosphor.

  2. High-performance chelation chromatography of metal ions on sorbents with grafted iminodiacetic acid

    International Nuclear Information System (INIS)

    Chromatographic behavior of some alkaline earth, transition, heavy (including uranium) and rare earth metal ions on a group of complexing sorbents, containing surface functional groups of imidodiacetic acid, was studied. Conditions, under which metal retention is determined by complexing on the sorbent surface, were defined and main principles of a new variant of liquid chromatography, i.e. high-performance chelating chromatography of metal ions (HPCCI) were formulated. It is shown that under optimal conditions metal retention correlates linearly in bilogarithmic coordinates with stability constants of the relevant metal complexes. Potentialities of HPCCI analytic application to analysis of objects featuring complex composition were considered

  3. Metal mobilization under alkaline conditions in ash-covered tailings.

    Science.gov (United States)

    Lu, Jinmei; Alakangas, Lena; Wanhainen, Christina

    2014-06-15

    The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings. PMID:24681363

  4. Magnetic Behavior of Some Rare-Earth Transition-Metal Perovskite Oxide Systems

    Institute of Scientific and Technical Information of China (English)

    Kenji Yoshii; Akio Nakamura; Masaichiro Mizumaki; Naoshi Ikeda; Jun'ichiro Mizuki

    2004-01-01

    Magnetic properties were investigated for the rare-earth 3d-transition metal oxides with the perovskite structure. Intriguing magnetic phenomena were reviewed for a few systems:magnetization peak effect in the titanates, magnetization reversal in the chromites and metallic ferromagnetism in the cobaltites. The results suggest an important role of the rare-earth ions for the magnetic properties of such complex oxides.

  5. Moessbauer effect of the alkaline and alkaline earth metal nitroprusside powders

    CERN Document Server

    Yang, T H; Kim, H S; Hong, C Y; Kim, H B; Cho, H Y; Kim, D Y; Moon, Y S

    2000-01-01

    We observe Moessbauer spectra of Fe atoms centered in nitroprusside anions of sodium nitroprusside (Na sub 2 [Fe(CN) sub 5 NO] 2H sub 2 O). potassium-nitroprusside (K sub 2 [Fe(CN)] sub 5 NO centre dot 2.5H sub 2 O), rubidium nitroprusside (Rb sub 2 [Fe(CN) sub 5 NO centre dot H sub 2 O), magnesium nitroprusside (Mg[Fe(CN) sub 5 NO], calcium nitroprusside (Ca[Fe(CN) sub 5 NO]centre dot 4H sub 2 O), and barium nitroprusside (Ba[Fe(CN) sub 5 NO]centre dot 3H sub 2 O) samples which have photochromic properties. We compare the Moessbauer parameters, the values of the isomer shifts and the quadrupole splittings of the samples with those of a sodium nitroprusside single crystal which is a standard material. The values of the isomer shifts and the quadrupole splittings of the various compounds are close to each other. The values of the line broadening of all samples are between 2.1 GAMMA sub N and 2.5 GAMMA sub N. The Moessbauer Lamb factors (f) are between 0.252(1) and 0.340(2). These values are obtained from the s...

  6. Molten metal reactor and method of forming hydrogen, carbon monoxide and carbon dioxide using the molten alkaline metal reactor

    Science.gov (United States)

    Bingham, Dennis N.; Klingler, Kerry M.; Turner, Terry D.; Wilding, Bruce M.

    2012-11-13

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  7. CP(N - 1) quantum field theories with alkaline-earth atoms in optical lattices

    Science.gov (United States)

    Laflamme, C.; Evans, W.; Dalmonte, M.; Gerber, U.; Mejía-Díaz, H.; Bietenholz, W.; Wiese, U.-J.; Zoller, P.

    2016-07-01

    We propose a cold atom implementation to attain the continuum limit of (1 + 1) -d CP(N - 1) quantum field theories. These theories share important features with (3 + 1) -d QCD, such as asymptotic freedom and θ-vacua. Moreover, their continuum limit can be accessed via the mechanism of dimensional reduction. In our scheme, the CP(N - 1) degrees of freedom emerge at low energies from a ladder system of SU(N) quantum spins, where the N spin states are embodied by the nuclear Zeeman states of alkaline-earth atoms, trapped in an optical lattice. Based on Monte Carlo results, we establish that the continuum limit can be demonstrated by an atomic quantum simulation by employing the feature of asymptotic freedom. We discuss a protocol for the adiabatic preparation of the ground state of the system, the real-time evolution of a false θ-vacuum state after a quench, and we propose experiments to unravel the phase diagram at non-zero density.

  8. CP(N-1) Quantum Field Theories with Alkaline-Earth Atoms in Optical Lattices

    CERN Document Server

    Laflamme, C; Dalmonte, M; Gerber, U; Mejía-Díaz, H; Bietenholz, W; Wiese, U -J; Zoller, P

    2015-01-01

    We propose a cold atom implementation to attain the continuum limit of (1+1)-d CP(N-1) quantum field theories. These theories share important features with (3+1)-d QCD, such as asymptotic freedom and $\\theta$ vacua. Moreover, their continuum limit can be accessed via the mechanism of dimensional reduction. In our scheme, the CP(N-1) degrees of freedom emerge at low energies from a ladder system of SU(N) quantum spins, where the N spin states are embodied by the nuclear Zeeman states of alkaline-earth atoms, trapped in an optical lattice. Based on Monte Carlo results, we establish that the continuum limit can be demonstrated by an atomic quantum simulation by employing the feature of asymptotic freedom. We discuss a protocol for the adiabatic state preparation of the ground state of the system, the real-time evolution of a false $\\theta$-vacuum state after a quench, and we propose experiments to unravel the phase diagram at non-zero density.

  9. Surface fractal dimensions and textural properties of mesoporous alkaline-earth hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Vilchis-Granados, J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico); Granados-Correa, F., E-mail: francisco.granados@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Barrera-Díaz, C.E. [Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico)

    2013-08-15

    This work examines the surface fractal dimensions (D{sub f}) and textural properties of three different alkaline-earth hydroxyapatites. Calcium, strontium and barium hydroxyapatite compounds were successfully synthesized via chemical precipitation method and characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and N{sub 2}-physisorption measurements. Surface fractal dimensions were determined using single N{sub 2}-adsorption/desorption isotherms method to quantify the irregular surface of as-prepared compounds. The obtained materials were also characterized through their surface hydroxyl group content, determined by the mass titration method. It was found that the D{sub f} values for the three materials covered the range of 0.77 ± 0.04–2.33 ± 0.11; these results indicated that the materials tend to have smooth surfaces, except the irregular surface of barium hydroxyapatite. Moreover, regarding the synthesized calcium hydroxyapatite exhibited better textural properties compared with the synthesized strontium and barium hydroxyapatites for adsorbent purposes. However, barium hydroxyapatite shows irregular surface, indicating a high population of active sites across the surface, in comparison with the others studied hydroxyapatites. Finally, the results showed a linear correlation between the surface hydroxyl group content at the external surface of materials and their surface fractal dimensions.

  10. Structure of alkaline-earth pentafluoroantimonates(III), MSbF5(M=Sr, Ba)

    International Nuclear Information System (INIS)

    Strontium pentafluoroantimonate(III), SrSbF5, Mr=304.36, orthorhombic, Pbcm, a=4.378 (1), b=8.853 (3), c=11.233 (4) A, V=435.4 (3) A3, Z=4, Dm=4.60, Dx=4.64 Mg m-3, Mo Kα, λ=0.71069 A, μ=18.9 mm-1, F(000)=536, T=298 K, R=0.028 for 596 independent reflections with I>3α(I). Barium pentafluoroantimonate(III), BaSbF5, Mr=354.08, orthorhombic, Pbcm, a=4.676 (1), b=9.313 (2), c=11.213 (3) A, V=488.3 (2) A3, Z=4, Dm=4.77, Dx=4.82 Mg m-3, Mo Kα, λ=0.71069 A, μ=13.6 mm-1, F(000)=608, T=298 K, R=0.015 for 914 independent reflections with I>3σ(I). SrSbF5 and BaSbF5 are isostructural compounds. The three-dimensional network consists of isolated SbF52- units which are connected by ten-coordinated alkaline-earth ions Sr2+ or Ba2+. The geometry of these pentafluoroantimonate ions is approximately square pyramidal with the Sb atom outside the pyramid, below the four F atoms constituting the basal plane. (orig.)D

  11. IR and Raman spectroscopic studies of sol–gel derived alkaline-earth silicate glasses

    Indian Academy of Sciences (India)

    Angelos G Kalampounias

    2011-04-01

    IR and Raman spectroscopies have been utilized to study the structure and vibrational modes of sol–gel-derived binary silicate glasses. The present study is motivated by the immense geological significance and focuses on the MO–SiO2 (M = Ca, Mg) binary systems in an effort to unveil the role of the CaO and MgO modifiers when incorporated to the 3D silica structure. Glasses in the composition range = 0, 0.1, 0.2, 0.3 and 0.4 prepared by the sol–gel method were compared with the corresponding glasses formed by appropriate mixing of SiO2 and MO powders through melting and fast cooling. The vibrational spectra of the sol–gel-derived glasses have revealed considerable changes in relative intensities as a function of the MO mole fraction. These changes signify structural modifications on the silica network. The population of the 3 species was found to increase for both modified silicate systems. The rate of increase is more pronounced in the CaO–SiO2 glasses. The extent of network depolymerization in the porous glass is higher at the same content of alkaline earth oxide compared to the bulk glass. The results are indicative of a more `defective’ nature of the sol–gel glasses compared to the corresponding melt-quenched ones.

  12. Mixed alkali effect on the spectroscopic properties of alkali-alkaline earth oxide borate glasses

    Science.gov (United States)

    Srinivas, G.; Ramesh, B.; Shareefuddin, Md.; Chary, M. N.; Sayanna, R.

    2016-05-01

    The mixed alkali and alkaline earth oxide borate glass with the composition xK2O - (25-x) Li2O-12.5BaO-12.5MgO-50B2O3 (x = 0, 5, 10, 15, 20 and 25mol %) and doped with 1mol% CuO were prepared by the melt quenching technique. From the optical absorption spectra the optical band gap, electronic polarizability(α02-), interaction parameter (A), theoretical and experimental optical basicity (Λ) values were evaluated. From the Electron Paramagnetic Resonance (EPR) spectral data the number of spins (N) and susceptibility (χ) were evaluated. The values of (α02-), and (Λ) increases with increasing of K2O content and electronic polarizability and interaction parameter show opposite behaviuor which may be due to the creation of non-bridging oxygens and expansion of borate network. The reciprocal of susceptibility (1/χ) and spin concentration (N) as a function of K2O content, varied nonlinearly which may be due to creation of non-bridging oxygens in the present glass system. This may be attributed to mixed alkali effect (MAE).

  13. New Transition metal assisted complex borohydrides for hydrogen storage

    International Nuclear Information System (INIS)

    High capacity hydrogen storage systems are indeed essential for the on-board vehicular application that leads to the pollution free environment. Apart from the various hydrogen storage systems explored in the past, complex hydrides involving light weight alkali/alkaline metals exhibits promising hydrogenation/ dehydrogenation characteristics. New transition metal assisted complex borohydrides [Zn(BH4)2] have been successfully synthesized by an inexpensive mechano-chemical process. These complex hydrides possesses gravimetric hydrogen storage capacity of ∼8.4 wt.% at around 120 C. We have determined the volumetric hydrogen absorption and desorption of these materials for a number of cycles. Another complex borohydride mixture LiBH4/MgH2 catalyzed with ZnCl2 has been synthesized and characterized using various analytical techniques. (authors)

  14. Effect of the nature of alkali and alkaline-earth oxides on the structure and crystallization of an alumino-borosilicate glass developed to immobilize highly concentrated nuclear waste solutions

    International Nuclear Information System (INIS)

    A complex rare-earth rich alumino-borosilicate glass has been proved to be a good candidate for the immobilization of new high level radioactive wastes. A simplified seven-oxides composition of this glass was selected for this study. In this system, sodium and calcium cations were supposed in other works to simulate respectively all the other alkali (R+ = Li+, Rb+, Cs+) and alkaline-earth (R2+ = Sr2+, Ba2+) cations present in the complex glass composition. Moreover, neodymium or lanthanum are used here to simulate all the rare-earths and actinides occurring in waste solutions. In order to study the impact of the nature of R+ and R2+ cations on both glass structure and melt crystallization tendency during cooling, two glass series were prepared by replacing either Na+ or Ca2+ cations in the simplified glass by respectively (Li+, K+, Rb+, Cs+) or (Mg2+, Sr2+, Ba2+) cations. From these substitutions, it was established that alkali ions are preferentially involved in the charge compensation of (AlO4)- entities in the glass network comparatively to alkaline-earth ions. The glass compositions containing calcium give way to the crystallization of an apatite silicate phase bearing calcium and rare-earth ions. The melt crystallization tendency during cooling strongly varies with the nature of the alkaline-earth. (authors)

  15. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure

    International Nuclear Information System (INIS)

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. - This study has demonstrated exposure to alkali, alkali earth and transition metals in pregnant women with factors such as breastfeeding, fish oil use and diet affecting exposures

  16. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO3 nanocomposites and rare earth metal complexes: Preparation and characterization

    International Nuclear Information System (INIS)

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb3+) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb3+ ions afforded fluorescent Tb3+ tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb3+) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb3+nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb3+ complexes were investigated by fluorescence spectroscopy

  17. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-03-30

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

  18. Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

    International Nuclear Information System (INIS)

    Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination, temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters

  19. Influence of solvent on proton transport in complexes of pyridine alkalines with trifluoroacetic acid

    International Nuclear Information System (INIS)

    The influence of solvent on proton transport in complexes of pyridine alkalines with trifluoroacetic acid was studied by nuclear magnetic resonance. The values of proton chemical shift are given. The influence of solution strength on chemical shift is also presented. (A.S.)

  20. Genesis of rare-metal pegmatites and alkaline apatite-fluorite rocks of Burpala massi, Northern Baikal folded zone

    Science.gov (United States)

    Sotnikova, Irina; Vladykin, Nikolai

    2015-04-01

    thermobarometric evidence suggests that apatite-fluorite rocks were formed from the residual fluid-melt, separated after crystallization of rare-metal pegmatites. Petrochemical and geochemical data Burpalinsky are in accord of general trend of crystal differentiation of alkaline magma containing small concentrations of CO2 and higher P2O5 and F, which accumulated significantly separated from the pegmatite melts. In some pegmatites fluorite with rare-metal minerals (flyuocerit etc) are separating in schlieren. Apatite-fluorite rocks are cut by leucogranite dyke, having genetic connection with rare-metal pegmatites. Late granitic phases has its own association of rare-metal minerals described by A.A. Ganzeev (1972). Thermobarometric geochemical study of apatite-fluorite rocks Burpala massif found a large number of primary fluid inclusions (15-50 micrometers). Thermal and cryometric research of 60 individual fluid inclusions in fluorite showed the domination of Na, Ca, Mg chlorides and high temperatures salt inclusions in fluorites (above 550C) and melt inclusions in apatites (800C). Apatite-fluorite rocks in massif are similar to foskorites in carbonatite complexes, with similar high Ca content, but instead fluorite, together with other "foskoritovymi" minerals - apatite, magnetite, mica, and pyroxene were formed instead for calcite. Isotopic studies (Sr-Nd) indicate the mantle source of primary magma Burpala massif close to EM-2, which is characteristic of alkaline intrusions in the folded belts (Vladykin 2009). RBRF grant 14-45-04057

  1. Analysis of the electronic dipole polarizability of ions in cubic oxides, fluorides, and sulfides of alkaline earth elements

    International Nuclear Information System (INIS)

    A new approach to calculating the electronic dipole polarizability of ions in crystals which is based on an analysis of the relationship between the electronic dipole polarizability of ion and its effective charge has been proposed. It is shown that applying this method to simple cubic oxides, fluorides, and sulfides of alkaline earth elements yields makes the calculation results consistent with the well-known data on the structure and type of bonds in these compounds.

  2. Alkaline earth lead and tin compounds Ae2Pb, Ae2Sn, Ae = Ca, Sr, Ba, as thermoelectric materials

    OpenAIRE

    David Parker and David J Singh

    2013-01-01

    We present a detailed theoretical study of three alkaline earth compounds Ca2Pb, Sr2Pb and Ba2Pb, which have undergone little previous study, calculating electronic band structures and Boltzmann transport and bulk moduli using density functional theory. We also study the corresponding tin compounds Ca2Sn, Sr2Sn and Ba2Sn. We find that these are all narrow band gap semiconductors with an electronic structure favorable for thermoelectric performance, with substantial thermopowers for the lead c...

  3. The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Guo, W., E-mail: guowei1982cry@163.com [College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Ma, H.A.; Jia, X. [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2014-03-01

    Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF{sub 2} > MgF{sub 2}. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF{sub 2} and MgF{sub 2}. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides.

  4. The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF2 > MgF2. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF2 and MgF2. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides

  5. Identification of a macro-alkaline phosphatase complex in a patient with inflammatory bowel disease.

    Science.gov (United States)

    McTaggart, Malcolm P; Rawson, Catherine; Lawrence, David; Raney, Barbara S; Jaundrill, Linnet; Miller, Lorna A; Murtinho-Braga, Joseph; Kearney, Edward M

    2012-07-01

    We report the rare finding of a macro-alkaline phosphatase (macroALP) complex in a patient with a previously unexplained raised alkaline phosphatase activity. The clinical symptoms were persistent, daily diarrhoea for two months with blood in the stool. The patient was subsequently diagnosed with inflammatory bowel disease, specifically ulcerative colitis, following a rectal biopsy and colonoscopy. Two cases of macroALP associated with ulcerative colitis have been reported before, suggesting there could be an increased prevalence of macroALP in these patients. PMID:22454544

  6. Ocean-Based Alkalinity Enhancement: Mitigation Potential, Side Effects and the Fate of Added Alkalinity Assessed in an Earth System Model

    Science.gov (United States)

    Gonzalez, M. F.; Ilyina, T.

    2014-12-01

    Artificial ocean alkalinization (AOA) has been proposed as a mean to mitigate climate change and ocean acidification. Whilst the mitigation potential of this geo-engineering technology may sound promising, it poses environmental risks. Within the Priority Program "Climate Engineering" of the German Science Foundation (DFG), we investigate the mitigation potential of AOA to reduce atmospheric CO2 and counteract the consequences of ocean acidification. We are particularly interested in the residence time of the added alkalinity at the ocean surface because it must stay in the upper ocean in order to increase the oceanic CO2 uptake. The mitigation potential, risks and the unintended consequences of this geo-engineering method are also exhaustively studied. These questions are tackled through the analysis of different alkalinity enhancement scenarios in the state-of-the-art Earth system model of the Max Planck Institute for Meteorology (MPI-ESM) in a configuration based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Model scenarios are designed so that AOA is performed to keep the atmospheric CO2 concentrations similar to values of the stabilization scenario RCP4.5, while fossil fuel CO2 emissions follow the pathway of the high-CO2 scenario RCP8.5. Alkalinity is added globally into the upper 12 meters of the ocean in different seasons and years. We found that on the time scale of relevance (i.e. from years to decades), season and location are key aspects to take into account in the implementation of AOA. This is because of inhomogeneous vertical mixing of added alkalinity due to the mixed layer depth which is established by the season. We also show that the rate of addition greatly determines impact and outcome of this geo-engineering method. Changes driven by the implementation of this method in the ocean biogeochemistry are also discussed. For instance, the associated changes in the carbon cycle, marine oxygen levels, saturation state of

  7. Electrowinning of high purity individual rare earth metals - a review

    International Nuclear Information System (INIS)

    Rare earth metals are finding applications in various fields. The demand for purer individual metals is increasing. The two important methods of preparation of the pure metals are Metallothermic Reduction and Electrowinning. In Electrowinning, the rare earth fluoride, chloride or oxide is elctrolysed using direct current. Fused salt electrolysis is the commonly used method. The important developments in the area of electrometallurgy is summarised in this paper. In general, the paper deals with the important findings and developments in the process development of electrowinning of rare earth elements. (author) 49 refs., 1 fig., 1 tab

  8. Many-body forces and stability of the alkaline-earth tetramers

    International Nuclear Information System (INIS)

    Graphical abstract: Many-body forces effect. In a three-particle system, the two-body interaction energies depend upon coordinates of all three particles. The comparative study of the interaction energy and its many-body decomposition for alkaline-earths tetramers Be4, Mg4, and Ca4 at the all-electron CCSD(T)/aug-cc-pVQZ level is performed. For study of dependence of the binding energy and the orbital population on the cluster size the corresponding dimers and trimers were also calculated at the same level of theory. In comparison with weakly bound dimers, the binding energy in trimers and, especially, in tetramers drastically increases; e.g., Eb/N in Be3 is 7 times larger and in Be4 is 18.4 times larger than in Be2. This sharp increase is explained as a manifestation of many-body forces. The trimers and tetramers are stabilized by the three-body forces, whereas the two- and four-body forces are repulsive. The attractive contribution to the three-body forces has a three-atom electron exchange origin. The natural bond orbital (NBO) population analysis reveals a relatively large np-population in trimers and tetramers. The population of the valence np-orbitals leads to the sp-hybridization providing the covalent bonding. Research highlights: → The alkaline-earths trimers and tetramers are stabilized by the three-body forces. → Two- and four-body forces are repulsive for trimers and tetramers. → The attractive contribution to the three-body forces has a three-atom electron exchange origin. → The population of the np-orbitals leads to the sp-hybridization providing the covalent bonding. - Abstract: The comparative study of the interaction energy and its many-body decomposition for Be4, Mg4, and Ca4 at the all-electron CCSD(T)/aug-cc-pVQZ level is performed. For study of dependence of the binding energy and the orbital population on the cluster size the corresponding dimers and trimers were also calculated at the same level of theory. In comparison with weakly

  9. Many-body forces and stability of the alkaline-earth tetramers

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Torrejon, C.C. [Centro Nacional de Supercomputo, IPICyT, A.C., Camino a la Presa San Jose 2055, 78216 San Luis Potosi, SLP (Mexico); Centro de Investigacion en Materiales Avanzados, S.C., Av. Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Kaplan, Ilya G., E-mail: kaplan@iim.unam.mx [Instituto de Investigaciones en Materiales, UNAM, Apdo. Postal 70-360, 04510 Mexico D.F. (Mexico)

    2011-03-18

    Graphical abstract: Many-body forces effect. In a three-particle system, the two-body interaction energies depend upon coordinates of all three particles. The comparative study of the interaction energy and its many-body decomposition for alkaline-earths tetramers Be{sub 4}, Mg{sub 4}, and Ca{sub 4} at the all-electron CCSD(T)/aug-cc-pVQZ level is performed. For study of dependence of the binding energy and the orbital population on the cluster size the corresponding dimers and trimers were also calculated at the same level of theory. In comparison with weakly bound dimers, the binding energy in trimers and, especially, in tetramers drastically increases; e.g., E{sub b}/N in Be{sub 3} is 7 times larger and in Be{sub 4} is 18.4 times larger than in Be{sub 2}. This sharp increase is explained as a manifestation of many-body forces. The trimers and tetramers are stabilized by the three-body forces, whereas the two- and four-body forces are repulsive. The attractive contribution to the three-body forces has a three-atom electron exchange origin. The natural bond orbital (NBO) population analysis reveals a relatively large np-population in trimers and tetramers. The population of the valence np-orbitals leads to the sp-hybridization providing the covalent bonding. Research highlights: {yields} The alkaline-earths trimers and tetramers are stabilized by the three-body forces. {yields} Two- and four-body forces are repulsive for trimers and tetramers. {yields} The attractive contribution to the three-body forces has a three-atom electron exchange origin. {yields} The population of the np-orbitals leads to the sp-hybridization providing the covalent bonding. - Abstract: The comparative study of the interaction energy and its many-body decomposition for Be{sub 4}, Mg{sub 4}, and Ca{sub 4} at the all-electron CCSD(T)/aug-cc-pVQZ level is performed. For study of dependence of the binding energy and the orbital population on the cluster size the corresponding dimers and

  10. Elaboration and test of the method of separation of alkaline metals ions with tin phosphate

    International Nuclear Information System (INIS)

    Present work is devoted to elaboration and test of the method of separation of alkaline metals ions with tin phosphate. Thus, the isotherms of sorption of lithium, sodium, potassium, rubidium and cesium ions with amorphous tin phosphate depending on their concentration, ph of solution, sorbent quantity are obtained. The parameters of extraction of potassium microquantities from sodium salts are defined. Ultra pure sodium chloride, sodium iodide, sodium sulphate, sodium nitrate, sodium nitrite, sodium phosphate are synthesized.

  11. Carbonate complexation of Np(IV) in alkaline solutions

    International Nuclear Information System (INIS)

    Reliable thermodynamic data for actinide (IV) have been required. The solubility of Np(IV) in carbonate media was studied for determination of thermodynamic data. The concentration of dissolved Np(IV) was measured with ionic strengths from 0.5 to 2.9 M (M ≡ mol·dm-3), hydrogen-ion concentration exponent (pHc = -log[H+]) from 8 to 13 and with the total carbonate concentration (CT) from 5x10-3 M to 7x10-1 M by an oversaturation method. It was found that the solubility of Np(IV) decreased with increasing pHc and increased with increasing CT. On the basis of analysis of the solubility data, the dominant aqueous species of Np(IV) were expected to be Np(CO3)44-, Np(CO3)2(OH)22- and Np(CO3)2(OH)44- in the present study. The apparent equilibrium constants of the carbonate and carbonatohydroxo complexes were obtained in the respective ionic strength and the equilibrium constants at the zero ionic strength were extrapolated. The obtained equilibrium constants supported the literature values strongly, and contributed to improve the reliability of the thermodynamic data. (author)

  12. Treatment of Alkaline Cr(VI)-Contaminated Leachate with an Alkaliphilic Metal-Reducing Bacterium.

    Science.gov (United States)

    Watts, Mathew P; Khijniak, Tatiana V; Boothman, Christopher; Lloyd, Jonathan R

    2015-08-15

    Chromium in its toxic Cr(VI) valence state is a common contaminant particularly associated with alkaline environments. A well-publicized case of this occurred in Glasgow, United Kingdom, where poorly controlled disposal of a cementitious industrial by-product, chromite ore processing residue (COPR), has resulted in extensive contamination by Cr(VI)-contaminated alkaline leachates. In the search for viable bioremediation treatments for Cr(VI), a variety of bacteria that are capable of reduction of the toxic and highly soluble Cr(VI) to the relatively nontoxic and less mobile Cr(III) oxidation state, predominantly under circumneutral pH conditions, have been isolated. Recently, however, alkaliphilic bacteria that have the potential to reduce Cr(VI) under alkaline conditions have been identified. This study focuses on the application of a metal-reducing bacterium to the remediation of alkaline Cr(VI)-contaminated leachates from COPR. This bacterium, belonging to the Halomonas genus, was found to exhibit growth concomitant to Cr(VI) reduction under alkaline conditions (pH 10). Bacterial cells were able to rapidly remove high concentrations of aqueous Cr(VI) (2.5 mM) under anaerobic conditions, up to a starting pH of 11. Cr(VI) reduction rates were controlled by pH, with slower removal observed at pH 11, compared to pH 10, while no removal was observed at pH 12. The reduction of aqueous Cr(VI) resulted in the precipitation of Cr(III) biominerals, which were characterized using transmission electron microscopy and energy-dispersive X-ray analysis (TEM-EDX) and X-ray photoelectron spectroscopy (XPS). The effectiveness of this haloalkaliphilic bacterium for Cr(VI) reduction at high pH suggests potential for its use as an in situ treatment of COPR and other alkaline Cr(VI)-contaminated environments. PMID:26048926

  13. Encapsulation of metal cations by the PhePhe ligand: a cation-pi ion cage

    NARCIS (Netherlands)

    R.C. Dunbar; J.D. Steill; J. Oomens

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a nove

  14. Encapsulation of Metal Cations by the PhePhe Ligand: A Cation-pi Ion Cage

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2011-01-01

    Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba2+ and Ca2+, the alkali-metal ions Li+, Na+, K+, and Cs+, and the transition-metal ion Ag+. The two neighboring aromatic side chains open the possibility of a nove

  15. Polyhydroxyflavones as extractants. Communication 7. Solvent extraction of europrium complexes with morin from alkaline media

    International Nuclear Information System (INIS)

    This paper studies the analytical application of europium (III)-morin complex which is formed in alkaline medium and has an intense color. The extent of europium extraction was determined by adding to the extract a morin solution in isoamyl alcohol in a 50-100-fold excess with respect to europium. The dependence of the optical density of the extracts on the ph in the system europium (III)-morin-water-organic solvent for different excesses of the reagent is shown: this indicates formation of two extractable complexes, one being dominant in the pH range 4-7, the other at pH greater than or equal to 8.5. The extraction of the europium (III)-morin complex from alkaline solution is used for direct extraction-photometric determination of europium(III) in compounds of elements having amphoteric properties or forming amines (Zns, Mo03)

  16. Refining of light rare, rare earth and radioactive metals

    International Nuclear Information System (INIS)

    Overview of technologies for the production of high-purity light rare, rare earth, radioactive metals and their compounds: electrolytic refining, vacuum distillation, electron-beam and zone melting, directed crystallization, electrotransfer, extraction, ion exchange

  17. Synthesis and crystal structures of novel LaOAgS-type alkaline earth – Zinc, manganese, and cadmium fluoride pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Charkin, Dmitri O., E-mail: charkin@inorg.chem.msu.ru; Urmanov, Arthur V.; Plokhikh, Igor V.; Korshunov, Alexander D.; Kuznetsov, Alexey N.; Kazakov, Sergey M.

    2014-02-05

    Highlights: • Sight new alkaline earth – Mn, Zn, Cd fluoride pnictides were prepared. • All new compounds adopt the LaOAgS structure type. • Bond distances in their structures are transferable within 2–3%. • Very close similarities are observed in structural chemistry of LaOAgS- and HfCuSi{sub 2}-type compounds of Mn, Cu, Zn, Ag, and Cd. -- Abstract: Systematic studies of the LaOAgS-type compounds among alkaline earth – Zn/Cd/Mn fluoride pnictides revealed the existence of new representatives SrFMnP, SrFMnAs, SrFMnSb, SrFZnAs, SrFZnSb, BaFZnAs, BaFCdP, and BaFCdAs. Similar to rare-earth oxide compounds and contrary to isolobal chalcogenides of Cu/Ag, not all possible compositions could be realized. No compound of the structure type is formed for calcium; strontium forms fluoride pnictides only with zinc and manganese, while for barium, new representatives are also formed with cadmium. This trend, which possibly has a geometrical origin, is corroborated by quantum chemical calculations. Formation of NdOZnP-type compounds also was not observed suggesting the structure to be characteristic only for rare earth – zinc oxide phosphides.

  18. Structure, bonding and energetics of N-heterocyclic carbene (NHC) stabilized low oxidation state group 2 (Be, Mg, Ca, Sr and Ba) metal complexes: A theoretical study

    Indian Academy of Sciences (India)

    Ashim Baishya; V Rao Mundlapati; Sharanappa Nembenna; Himansu S Biswal

    2014-11-01

    A series of N-heterocyclic carbene stabilized low oxidation state group 2 metal halide and hydrides with metal-metal bonds ([L(X) M-M(X) L]; L = NHC ((CHNH)2C:), M = Be, Mg, Ca, Sr and Ba, and X = Cl or H) has been studied by computational methods. The main objective of this study is to predict whether it is possible to stabilize neutral ligated low oxidation state alkaline-earth metal complexes with metal-metal bonds. The homolytic metal-metal Bond Dissociation Energy (BDE) calculation, Natural Bond Orbital (NBO) and Energy Decomposition Analyses (EDA) on density functional theory (DFT) optimized [L(X)M-M(X)L] complexes revealed that they are as stable as their -diketiminate, guanidinate and -diimine counterparts. The optimized structures of the complexes are in trans-linear geometries. The bond order analyses such as Wiberg Bond Indices (WBI) and Fuzzi Bond Order (FBO) confirm the existence of single bond between two metal atoms, and it is covalent in nature.

  19. Actinides and rare earths complexation with adenosine phosphate nucleotides

    International Nuclear Information System (INIS)

    demonstrated that the dominant interaction is between the cations and the phosphate groups of the ligands. Complexes with monophosphate ligands (AMP-Lu, Lu-Th-AEP and AMP) show similar organizations with bridging phosphates indicating that the organic part does not have a significant effect on their structure. ADP and ATP solid state complexes (with two spheroid metal ions: Lu and Th) show several similarities in terms of local environment indicating that the occurrence of a third phosphate group has no significant effect on the local organization of the complex. However, despite the theoretical approaches that have been conducted, the right structure of these complexes has not been accurately determined. Complexes of lanthanides and actinide(III) (Am) with ATP behave similarly at macroscopic level suggesting an identical structure at the molecular level for these complexes. With uranyl, U-AMP complex synthesized at acidic pH show different behaviour at molecular level than that observed at alkaline pH but the same coordination sites (phosphates and hydroxyls ribose groups) have been demonstrated for both complexes. (author)

  20. Monte Carlo simulations of electron thermalization in alkali iodide and alkaline-earth fluoride scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhiguo; Gao Fei; Kerisit, Sebastien [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Xie Yulong [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Campbell, Luke W. [National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2012-07-01

    A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF{sub 2} and BaF{sub 2}. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF{sub 2}, BaF{sub 2}, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident {gamma}-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs{sup +} relative to Na{sup +}, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.

  1. Monte Carlo simulations of electron thermalization in alkali iodide and alkaline-earth fluoride scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhiguo; Xie, YuLong; Campbell, Luke W.; Gao, Fei; Kerisit, Sebastien N.

    2012-07-01

    A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF2 and BaF2. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 {per_thousand}nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF2, BaF2, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident {gamma}-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs+ relative to Na+, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.

  2. Monte Carlo simulations of electron thermalization in alkali iodide and alkaline-earth fluoride scintillators

    International Nuclear Information System (INIS)

    A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF2 and BaF2. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF2, BaF2, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident γ-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs+ relative to Na+, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.

  3. Influence of Rare Earth on Carbide in Weld Metal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan-Bin; REN Deng-Yi

    2003-01-01

    The influence of rare earths (RE) on carbides in high carbon steel weld metal was studied by transmission electron microscope (TEM) and energy dispersive X-ray microanalysis (EDX). It is found that rare earth markedly affects the quantity, morphology and distribution of carbides. The precipitating mechanism of carbides was proposed in which rare earth compounds with high surface energy serve as the nucleation sites for carbides in superheated liquid metal and the induced carbides are precipitated extensively and distributed evenly. The preferential precipitation of carbides decreases the carbon content in matrix, which is transformed into low carbon lath martensite after welds are chilled to room temperature.

  4. Precise U-Pb Zircon Dating of the Syenite Phase from the Ditrau Alkaline Igneous Complex

    Directory of Open Access Journals (Sweden)

    Pană Dinu

    2000-04-01

    Full Text Available The Ditrău igneous complex represents the largest alkaline intrusion in the Carpathian-Pannonian region consisting of a plethora of rock types formed by complicated magmatic and metasomatic processes. A detailed U-Pb zircon age study is currently underway and the results for the syenite intrusion phase is reported herein. The U-Pb zircon emplacement age of the syenite of 229.6 +1.7/-1.2 Ma documents the quasi-contemporaneous production and emplacement of the gabbro and syenite magmas. We suggest that the syenite and associated granite formed by crustal melting during the emplacement of the mantle derived gabbroic magma around 230 Ma. The thermal contact aureole produced by the Ditrău alkaline igneous complex constrains the main tectonism recorded by surrounding metamorphic lithotectonic assemblages to be pre-Ladinian.

  5. Radiological Mapping of the Alkaline Intrusive Complex of Jombo, South Coastal Kenya by In-Situ Gamma-Ray Spectrometry

    Science.gov (United States)

    Kaniu, Ian; Darby, Iain G.; Kalambuka Angeyo, Hudson

    2016-04-01

    Carbonatites and alkaline intrusive complexes are rich in a variety of mineral deposits such as rare earth elements (REEs), including Nb, Zr and Mn. These are often associated with U and Th bearing minerals, including monazite, samarskite and pyrochlore. Mining waste resulting from mineral processing activities can be highly radioactive and therefore poses a risk to human health and environment. The Jombo complex located in Kenya's south coastal region is potentially one of the richest sources of Nb and REEs in the world. It consists of the main intrusion at Jombo hill, three associated satellite intrusions at Mrima, Kiruku and Nguluku hills, and several dykes. The complex is highly heterogeneous with regard to its geological formation as it is characterized by alkaline igneous rocks and carbonatites which also influence its radio-ecological dynamics. In-situ gamma spectrometry offers a low-cost, rapid and spatially representative radioactivity estimate across a range of landscapes compared to conventional radiometric techniques. In this work, a wide ranging radiological survey was conducted in the Jombo complex as follow up on previous studies[1,2], to determine radiation exposure levels and source distributions, and perform radiological risk assessments. The in-situ measurements were carried out using a 2.0 l NaI(Tl) PGIS-2 portable detector from Pico Envirotec Inc integrated with GPS, deployed for ground (back-pack) and vehicular gamma-ray spectrometry. Preliminary results of radiological distribution and mapping will be presented. [1] Patel, J. P. (1991). Discovery and Innovation, 3(3): 31-35. [2] Kebwaro, J. M. et. al. (2011). J. Phys. Sci., 6(13): 3105-3110.

  6. High Temperature Alkaline Electrolysis Cells with Metal Foam Based Gas Diffusion Electrodes

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2016-01-01

    Alkaline electrolysis cells operating at 250°C and 40 bar are able to convert electrical energy into hydrogen at very high efficiencies and power densities. In the present work we demonstrate the application of a PTFE hydrophobic network and Ag nanowires as oxygen evolution electrocatalyst in the...... metal foam based gas diffusion electrodes. A novel cell production method, based on tape casting and hot pressing, was developed which allows to increase the cell size from lab scale (1 cm2) to areas of 25 cm2 or larger. The thickness of the electrolyte matrix could be adjusted to only 200 μm, achieving...... novel cell concept promises more than a 10-fold improvement in power density, compared to conventional alkaline electrolysis cells, and thereby equivalent reduction in stack size and cost....

  7. Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace element geochemistry

    Science.gov (United States)

    Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David

    2014-03-01

    We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the

  8. Combined Electric, Electromagnetic and Gamma Spectrometric Methods Applied to the Pariquera-Açu Alkaline Complex

    Directory of Open Access Journals (Sweden)

    Elaine Maria Lopes Loureiro

    2011-08-01

    Full Text Available The Pariquera-Açu Alkaline Complex, located in the city of Pariquera-Açu (State of São Paulo, is one of the Brazilianalkaline complexes which has considerable mining potential. The combined use of several methods helped to determinepossible areas for exploration. Geophysical prospecting methods were used to assess the exploration potential of theseareas. The methods used in this study were gamma-spectrometry, induced polarization and electrical survey. Previousgeophysical studies were carried out to better understand the structural evolution of the complex and were not limited tothe study of the lithological variation. Gravimetric studies showed a zone of intense fenitization, which is consistent withalkaline complexes with carbonatites. A dipole-dipole survey conducted in the central part of the complex indicated thepresence in the subsurface of a resistive lithology with high chargeability. These factors, together with other studies onthe alkaline complex, suggest the presence of carbonatite in the area, which is corroborated by gamma spectrometry data,given the concentrations of Th (8 ppm and U (3.5 ppm and considering that the measurements were performed over a nonradioactivesedimentary cover.

  9. Optical Feshbach resonances of Alkaline-Earth atoms in a 1D or 2D optical lattice

    OpenAIRE

    Naidon, Pascal; Julienne, Paul S.

    2006-01-01

    Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96, 203201], we present the theory for photoassociation and optical Feshbach resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional (2D) optical lattice. In the case of an alkaline-earth intercombination resonance, the narrow natural width of the line makes it possible to observe clear manifestations of the dimensionality, as well as some sensitivity to the scattering length of the atoms. Among po...

  10. Gibbs free energies of coordination number change for a number of cations of rare-earth metals and yttrium

    International Nuclear Information System (INIS)

    Changes of Gibbs energies (ΔG) were calculated at variation of coordination number of rare earth and yttrium cations during formation of high-temperature superconductors from ordinary oxides. It is established that ΔG data are positive at changing coordination of ions in the range from samarium to lutetium and yttrium, the enthalpy contribution in ΔG prevails as compared with the entropy contribution, heavy alkaline earth metal ions are thermodynamic stabilizers for high-temperature superconductors. Suggested approach admits of evaluation of outlook for selective methods for synthesis of complicated coordination compounds at deficit of thermodynamic information

  11. Progress in alkaline peroxide dissolution of low-enriched uranium metal and silicide targets

    International Nuclear Information System (INIS)

    This paper reports recent progress on two alkaline peroxide dissolution processes: the dissolution of low-enriched uranium metal and silicide (U3Si2) targets. These processes are being developed to substitute low-enriched for high-enriched uranium in targets used for production of fission-product 9'9Mo. Issues that are addressed include (1) dissolution kinetics of silicide targets, (2) 99Mo lost during aluminum dissolution, (3) modeling of hydrogen peroxide consumption, (4) optimization of the uranium foil dissolution process, and (5) selection of uranium foil barrier materials. Future work associated with these two processes is also briefly discussed. (author)

  12. Superconductivity at 31 K in Alkaline Metal-Doped Cobalt Oxides

    Institute of Scientific and Technical Information of China (English)

    闻海虎; 杨海朋; 鲁希锋; 闫静

    2003-01-01

    By using a simple solid reaction method, we have fabricated alkaline metal doped cobalt oxides Anx CoO2+δ(An = Na, K). The magnetic measurement shows a superconducting-like diamagnetic signal at 31 K based on a strong superparamagnetic signal. Below 31 K, the magnetization hysteresis loops contain a strong rough linear superparamagnetic background and a superconducting hysteresis. The typical magnetization hysteresis loops for a type-Ⅱ superconductor are found. Preliminary resistive data also show a fast dropping of resistance below Tc.These give indication of superconductivity below 31 K in Anx CoO2+δ (An = Na, K).

  13. Novel alkaline earth copper germanates with ferro and antiferromagnetic S=1/2 chains

    International Nuclear Information System (INIS)

    Two new alkaline earth copper(II) germanates were hydrothermally synthesized: CaCuGeO4·H2O (1) and BaCu2Ge3O9·H2O (2), and their structures determined by single crystal X-ray diffraction. Compound (1) crystallizes in space group P21/c with a=5.1320(2) Å, b=16.1637(5) Å, c=5.4818(2) Å, β=102.609(2)°, V=443.76(3) Å3 and Z=4. This copper germanate contains layers of composition [CuGeO4]∞2− comprising CuO4 square planes and GeO4 tetrahedra with calcium and water molecules in the inter-layer space. Compound (2) crystallizes in the Cmcm space group with a=5.5593(3) Å, b=10.8606(9) Å, c=13.5409(8) Å, V=817.56(9) Å3 and Z=4. This structure contains GeO6 and CuO6 octahedra as well as GeO4 tetrahedra, forming a three-dimensional network of interconnecting six-membered ring channels. The magnetic susceptibility for both samples can be interpreted as S=1/2 chains, in agreement with the copper topology observed in the crystal structure. The susceptibility of (1) exhibits a Bonner–Fisher type behavior, resulting from antiferromagnetic intra-chain interactions without three-dimensional ordering down to 5 K—the lowest measured temperature. This observation, together with the absence of super-exchange paths between the copper chains, make this system particularly promising for the study of low dimensional magnetism. The magnetic properties of (2) show a very weak ferromagnetic near-neighbor interaction along the chain. In this compound a peak the χT plot seems to indicate the onset of interchain antiferromagentic correlations. However, no ordering temperature is detected in the susceptibility data. - Graphical abstract: Copper chains present in CaCuGeO4·H2O and BaCu2Ge3O9·H2O, two novel copper germanates synthesized hydrothermally, showing antiferromagnetic and ferromagnetic intra-chain interactions respectively. Highlights: ► The structure of two new chain containing copper germinates is reported. ► The calcium compound CaCuGeO4·H2O contains

  14. Inhibition of acid, alkaline, and tyrosine (PTP1B) phosphatases by novel vanadium complexes.

    Science.gov (United States)

    McLauchlan, Craig C; Hooker, Jaqueline D; Jones, Marjorie A; Dymon, Zaneta; Backhus, Emily A; Greiner, Bradley A; Dorner, Nicole A; Youkhana, Mary A; Manus, Lisa M

    2010-03-01

    In the course of our investigations of vanadium-containing complexes for use as insulin-enhancing agents, we have generated a series of novel vanadium coordination complexes with bidentate ligands. Specifically we have focused on two ligands: anthranilate (anc(-)), a natural metabolite of tryptophan, and imidizole-4-carboxylate (imc(-)), meant to mimic naturally occurring N-donor ligands. For each ligand, we have generated a series of complexes containing the V(III), V(IV), and V(V) oxidation states. Each complex was investigated using phosphatase inhibition studies of three different phosphatases (acid, alkaline, and tyrosine (PTP1B) phosphatase) as prima facia evidence for potential use as an insulin-enhancing agent. Using p-nitrophenyl phosphate as an artificial phosphatase substrate, the levels of inhibition were determined by measuring the absorbance of the product at 405nm using UV/vis spectroscopy. Under our experimental conditions, for instance, V(imc)(3) appears to be as potent an inhibitor of alkaline phosphatase as sodium orthovanadate when comparing the K(cat)/K(m) term. VO(anc)(2) is as potent an inhibitor of acid phosphatase and tyrosine phosphatase as the Na(3)VO(4). Thus, use of these complexes can increase our mechanistic understanding of the effects of vanadium in vivo. PMID:20071031

  15. Petrography, age and origin of the Schiel alkaline complex, northern Transvaal, South Africa

    Science.gov (United States)

    Barton, J. M.; Barton, E. S.; Smith, C. B.

    1996-02-01

    UPb ion microprobe data for zircon from syenitic phases of the Schiel alkaline complex, South Africa, indicate that it was emplaced at about 1.85 Ga and that it contains xenocrystic zircon of about 2.0 Ga and Archaean ages. Zircon with an age of 2.0 Ga may be derived from the hornblende granite (fenite) associated with the complex. In contrast, RbSr and uranogenic PbPb whole rock data suggest an age of about 2.1 Ga and may reflect mixing of Pb from at least two sources: the lithospheric source of the magma and the crust into which the magma was intruded. SmNd whole-rock isotopic data yield an apparent isochron age of about 2.3 Ga, but are interpreted to indicate that the syenitic magma was derived from a lithospheric source that underwent LREE enrichment between about 2.6 and 2.8 Ga ago. This source is chemically similar to that of the 2.05 Ga Phalaborwa complex, suggesting that both complexes were derived from a common, more primitive source but at different times. Emplacement of the Schiel alkaline complex may have been related to rifting leading to deposition of the rocks of the Soutpansberg Group.

  16. Method for treating rare earth-transition metal scrap

    Science.gov (United States)

    Schmidt, Frederick A.; Peterson, David T.; Wheelock, John T.; Jones, Lawrence L.

    1992-12-29

    Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

  17. Analytical study, by modelling methods, of the alkali and alkaline earth cations influence on the stability and the reactivity of aluminium (III) oxides or halides complexes; Etude analytique, par des techniques de modelisation, de l`influence de cations alcalins ou alcalino-terreux sur la stabilite et la reactivite de complexes de l`aluminium(III) avec des ions halogenures ou oxydes

    Energy Technology Data Exchange (ETDEWEB)

    Bouyer, F.

    1995-10-05

    The electric power consumption in aluminium production and electrorefining processes is high. A study of the electrochemical processes can be very useful for a better understanding of phenomena in electrolytic baths and then for reducing the production costs. A structural and vibrational analysis of species which exist in ionic solutions has been carried out with software based on the functional density theory. Concerning the electrolyte used for the aluminium refining, the anions study has shown that the aluminium chloro-fluoride complexes are preferentially tetrahedral. Moreover, the aluminium oxyfluoride complexes structures (which come from the alumina dissolution in cryolitic media) have been analyzed in the same way and the preferential coordination numbers for aluminium and oxygen have been shown clearly. The anionic model (which is limited to the nearest aluminium neighbours) does not allow to account for the thermodynamics of the cryolitic media. A more elaborated model has then been found to obtain the cryolite structure. The reactions enthalpies have been estimated and have lead to the calculus of species concentration gradients in liquid phase. The counterions effects as for instance sodium and calcium have been investigated. A model for the gaseous phase allowing to know the preferential species has been given. At last, a statistic thermochemistry program has been conceived and developed. It gives the thermodynamical functions at all temperature for the different complexes and allows to reckon the reactions coefficients in gaseous phase as well as the partial pressures profiles with those of calcium and sodium fluorides. (O.M.) 204 refs.

  18. Three interesting coordination compounds based on metalloligand and alkaline-earth ions: Syntheses, structures, thermal behaviors and magnetic property

    Science.gov (United States)

    Zhou, Qiang; Qian, Jun; Zhang, Chi

    2016-09-01

    Based on metalloligand LCu ([Cu(2,4-pydca)2]2-, 2,4-pydca2- = pyridine-2,4-dicarboxylate) and alkaline-earth ions (Ca2+, Sr2+, and Ba2+), three interesting coordination compounds, [Ca(H2O)7][LCu·H2O]·H2O (1), {Sr[LCu·H2O]·4H2O}n (2), and {Ba[LCu·H2O]·8H2O}n (3), have been synthesized and well-characterized by elemental analysis, infrared spectroscopy, thermogravimetric and single-crystal X-ray diffraction analysis. X-ray crystallographic studies reveal that 1 features a discrete 0D coordination compound, while 2 and 3 exhibit the 2D network and 1D chain structures, respectively. Compound 2 is constructed from {LCu}2 dimers connected with {Sr2} units, which is fabricated by two Sr2+ ions bridged via two μ2-O bridges, while compound 3 is formed by 1D {Ba}n chain linked with metalloligands LCu and exhibits an interesting sandwich like chain structure. It is noted that the coordination numbers of alkaline-earth ions are in positive correlation with their radiuses. Moreover, the magnetic property of compound 2 has been studied.

  19. Dymethyl sulfoxide complexes of rare earth perrhenates

    International Nuclear Information System (INIS)

    The complexes Ln(ReO4)3.8dmso (Ln = La-Lu, Y) and La(ReO4)3.8dmso-d6 have been prepared and characterized by conductance, infrared and Raman measurements. All the complexes have structures involving complex cation and non-coordinated anions in the solid state. The conductance values in nitromethane solution indicate a behavior near to a 1:1 electrolyte type. A comparative study with the data accumulated on the literature shows that perrhenate anion has higher coordinating capacity than perchlorate and hexafluorophosphate ones. (Author)

  20. Tolerance of Chemoorganotrophic Bioleaching Microorganisms to Heavy Metal and Alkaline Stresses

    Science.gov (United States)

    Monballiu, Annick; Cardon, Nele; Tri Nguyen, Minh; Cornelly, Christel; Meesschaert, Boudewijn; Chiang, Yi Wai

    2015-01-01

    The bioleaching potential of the bacterium Bacillus mucilaginosus and the fungus Aspergillus niger towards industrial residues was investigated by assessing their response towards various heavy metals (including arsenic, cadmium, cobalt, chromium, nickel, lead, and zinc) and elevated pH. The plate diffusion method was performed for each metal to determine the toxicity effect. Liquid batch cultures were set up for more quantitative evaluation as well as for studying the influence of basicity. Growth curves were prepared using bacterial/fungal growth counting techniques such as plate counting, optical density measurement, and dry biomass determination. Cadmium, nickel, and arsenite had a negative influence on the growth of B. mucilaginosus, whereas A. niger was sensitive to cadmium and arsenate. However, it was shown that growth recovered when microorganisms cultured in the presence of these metals were inoculated onto metal-free medium. Based on the findings of the bacteriostatic/fungistatic effect of the metals and the adaptability of the microorganisms to fairly elevated pH values, it is concluded that both strains have potential applicability for further research concerning bioleaching of alkaline waste materials. PMID:26236176

  1. Tolerance of Chemoorganotrophic Bioleaching Microorganisms to Heavy Metal and Alkaline Stresses

    Directory of Open Access Journals (Sweden)

    Annick Monballiu

    2015-01-01

    Full Text Available The bioleaching potential of the bacterium Bacillus mucilaginosus and the fungus Aspergillus niger towards industrial residues was investigated by assessing their response towards various heavy metals (including arsenic, cadmium, cobalt, chromium, nickel, lead, and zinc and elevated pH. The plate diffusion method was performed for each metal to determine the toxicity effect. Liquid batch cultures were set up for more quantitative evaluation as well as for studying the influence of basicity. Growth curves were prepared using bacterial/fungal growth counting techniques such as plate counting, optical density measurement, and dry biomass determination. Cadmium, nickel, and arsenite had a negative influence on the growth of B. mucilaginosus, whereas A. niger was sensitive to cadmium and arsenate. However, it was shown that growth recovered when microorganisms cultured in the presence of these metals were inoculated onto metal-free medium. Based on the findings of the bacteriostatic/fungistatic effect of the metals and the adaptability of the microorganisms to fairly elevated pH values, it is concluded that both strains have potential applicability for further research concerning bioleaching of alkaline waste materials.

  2. Distribution of radioactive anomalies at Morro do Ferro hill in Pocos de Caldas Alkaline Complex, MG

    International Nuclear Information System (INIS)

    Sistematic radiation intensity measurements were alone at Morro do Ferro hill in the Pocos de Caldas Alkaline Complex, using portable Scintrex spectrometer for U, Th, K and total counting (TC). Complementary geochemical analyses were alone on selected 26 samples. It was observed that there are many radiation focii in that place and they are oriented in the E-W direction. The geochemical analyses show that Uranium has participated also in the inicial mineralization of radioactive elements. The contribution of 238U series daugher elements is relatively strong although Uranium was 'washed' by leaching. (Author)

  3. Calc-alkaline magmatism at the Archean-Proterozoic transition : The caic complex basement (NE Brazil)

    OpenAIRE

    De Souza, Z. S.; Martin, Hervé; Peucat, J. J.; Jardim de Sa, E. F.; De Freitas Macedo, M. H.

    2007-01-01

    The Paleoproterozoic metaplutonic rocks of the Caico Complex Basement (Serid region, NE Brazil) provide important and crucial insights into the petrogenetic processes governing crustal growth and may potentially be a proxy for understanding the ArcheanProterozoic transition. These rocks consist of high-K calc-alkaline diorite to granite, with RbSr, UPb, PbPb and SmNd ages of c. 225215 Ga. They are metaluminous, with high Yb-N, K2O/Na2O and Rb/Sr, low I-Sr ratios, and are large ion lithophile ...

  4. Isolation of radioactive strontium from natural samples. Separation of strontium from alkaline and alkaline earth elements by means of mixed solvent anion exchange

    International Nuclear Information System (INIS)

    This paper presents the results of studies which led to the procedures for the chromatographic separation of radioactive strontium from alkaline, earth-alkaline and other elements in natural samples, on columns filled with strong base anion exchangers using alcoholic solutions of nitric acid as eluents. It has been shown that potassium, caesium, calcium, barium, yttrium and strontium can be adsorbed on strong base anion exchangers of the Dowex and Amberlite type, which contain the quaternary ammonium group with nitrate as counter-ion, from solutions of nitric acid in alcohol. Adsorption strength increases in the order methanol 3 in methanol, while they are adsorbed from ethanol and propanol. The adsorption strength is influenced by the polarity of alcohol, by the concentration of nitrate and by pH. The strength with which strontium adsorbs on the exchangers increases in the interval from 0 to 0.25M NH4NO3 in methanol, after which it starts to decrease. Strontium adsorbs to the exchangers from the alcoholic solution of ammonium nitrate twice as strongly as from the alcoholic solution of nitric acid, while a fraction of water in pure alcohol exceeding 10% prevents adsorption. In the mixture of alcohol and nitric acid, the adsorption strength for calcium and strontium increases with the increase of the volume fraction of alcohol with a lower dielectric constant. The rate and strength of adsorption of ions on the exchanger also increase in the series 0.25M HNO3 in methanol 3 in ethanol 3 in 1-propanol for each individual ion, as well as in the Ca3 in methanol, 0.25M HNO3 in ethanol and 0.25M HNO3 in propanol. Separation is also possible from alcohol mixtures. Strontium separation is most difficult from calcium, while the efficiency of separation increases with a decrease of the polarity of the used alcohol or alcohol mixture. The first group elements of the periodic table are not separated from each other in this way, while the elements of the second group are

  5. Characterization of Anthraquinone-DerivedRedox Switchable Ionophores and Their Complexes with Li+, Na+, K+, Ca+, and Mg+ Metal Ions

    Directory of Open Access Journals (Sweden)

    Vaishali Vyas

    2011-01-01

    Full Text Available Anthraquinone derived redox switchable ionophores 1,5 bis (2-(2-(2-ethoxy ethoxy ethoxyanthracene-9,10-dione (V1 and 1,8-bis(2-(2-(2-ethoxyethoxyethoxy anthracene—9,10-dione (V2 have been used for isolation, extraction and liquid membrane transport studies of Li+, Na+, K+, Ca2+ and Mg2+ metal ions. These isolated complexes were characterized by melting point determination, CV and IR, 1H NMR spectral analysis. Ionophore V2 shows maximum shift in reduction potential (ΔE with Ca(Pic2. The observed sequence for the shifting in reduction potential (ΔE between V2 and their complexes is V2 calcium picrate (42 mV > V2 potassium picrate (33 mV > V2 lithium picrate (25 mV > V2 sodium picrate (18 mV > V2 magnesium picrate (15 mV. These findings are also supported by results of extraction, back extraction and transport studies. Ionophore V2 complexed with KPic and showed much higher extractability and selectivity towards K+ than V1. These synthetic ionophores show positive and negative cooperativity towards alkali and alkaline earth metal ions in reduced and oxidized state. Hence, this property can be used in selective separation and enrichment of metal ions using electrochemically driven ion transport.

  6. Formation of a vitamin B-12-serum complex on heating at alkaline pH

    International Nuclear Information System (INIS)

    The binding of vitamin B-12 to serum proteins during heating at alkaline pH was investigated by gel filtration of serum supplemented with cyano[57Co]-cobalamin. Heating for 5 min at 1000C destroyed most of the vitamin B-12 binding activity of serum but, with further heating, the vitamin B-12 became incorporated into a complex that did not correspond in molecular size to the original vitamin B-12 binding proteins. Radioassay of vitamin B-12 in heated serum showed correspondingly first an increase then a progressive decrease in the apparent vitamin B-12 level suggesting that, on heating, vitamin B-12 was initially released then subsequently complexed by the serum. The formation of complexed vitamin B-12 was abolished by the presence of the reducing agent dithiothreitol during the heating step. (Auth.)

  7. Electrocatalytic oxidation of ethanol on various metal ad-layer modified Au(111) electrodes in alkaline solution

    OpenAIRE

    DURSUN, Zekerya; KARABİBEROĞLU, Şükriye ULUBAY; GELMEZ, Buket

    2011-01-01

    Ethanol oxidation was studied on single-crystal Au(111) electrodes that were modified by platinum, palladium, and cadmium metal ad-layers. The metal ad-layer modification was carried out by the underpotential deposition process, in which controlled amounts of Pt, Pd, and Cd were electrodeposited onto the substrate as submonolayer or monolayer coverage. The activity of the metal ad-layer modified Au(111) electrodes toward ethanol oxidation was studied in alkaline media, and recorded v...

  8. Determination of rare earth elements, uranium and thorium in geological samples by ICP-MS, using an automatic fusion machine as an alkaline digestion tool.

    Science.gov (United States)

    Granda, Luis; Rivera, Maria; Velasquez, Colon; Barona, Diego; Carpintero, Natalia

    2014-05-01

    At the present time, rare earth elements deposits have became in strategic resources for extraction of raw materials in order to manufacture high tech devices (computers, LCD, cell phones, batteries for hybrid vehicles, fiber optics and wind turbines) (1).The appropriate analytical determination of the REE ( rare earth elements) in sediment and rock samples , is important to find potential deposits and to recognize geological environments for identifying possible alterations and mineral occurrences. The alkaline fusion, which aim is to move the entire sample from solid to liquid state by forming water soluble complexes of boron and lithium, as a previous procedure for the determination of these elements, usually takes a lot of time due to the complexity of the analysis phase and by the addition of other reagents (Tm and HF ) (2) to compensate the lack of strict temperature control. The objective of this work is to develop an efficient alternative to alkaline digestion using an electrical fusion machine, which allows to create temperature programs with advanced process control and supports up to 5 samples simultaneously, which generates a reproducibility of the method and results during the melting step. Additionally, this new method permits the processing of a larger number of samples in a shorter time. The samples analyzed in this method were weighed into porcelain crucibles and subjected to calcination for 4 hours at 950 ° C in order to determine the Lost on Ignition (LOI ) , that serves to adjust the analytical results and to preserve the shelf life of the platinum ware. Subsequently, a fraction of the calcined sample was weighed into platinum crucibles and mixed with ultra-pure lithium metaborate ( flux ) 1:4 . The crucible was then placed in the fusion machine, which was programmed to take the sample from room temperature to 950 ° C in five minutes, make a small ramp to 970 ° C maintain that temperature for five minutes and download the melt in a 10 % v / v

  9. Dispersion coefficients for the interaction of inert gas atoms with alkali and alkaline earth ions and alkali atoms with their singly ionized ions

    CERN Document Server

    Singh, Sukhjit; Sahoo, B K; Arora, Bindiya

    2016-01-01

    We report the dispersion coefficients for the interacting inert gas atoms with the alkali ions, alkaline earth ions and alkali atoms with their singly charged ions. We use our relativistic coupled-cluster method to determine dynamic dipole and quadrupole polarizabilities of the alkali atoms and singly ionized alkaline earth atoms, whereas a relativistic random phase approximation approach has been adopted to evaluate these quantities for the closed-shell configured inert gas atoms and the singly and doubly ionized alkali and alkaline earth atoms, respectively. Accuracies of these results are adjudged from the comparison of their static polarizability values with their respective experimental results. These polarizabilities are further compared with the other theoretical results. Reason for the improvement in the accuracies of our estimated dispersion coefficients than the data listed in [At. Data and Nucl. Data Tables 101, 58 (2015)] are discussed. Results for some of the atom-ion interacting systems were not...

  10. Model for trace metal exposure in filter-feeding flamingos at alkaline Rift Valley Lake, Kenya

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Y.M.; DiSante, C.J.; Lion, L.W. [Cornell Univ., Ithaca, NY (United States). School of Civil and Environmental Engineering; Thampy, R.J.; Raini, J.A. [Worldwide Fund for Nature, Nakuru (Kenya). Lake Nakuru Conservation and Development Project; Motelin, G.K. [Egerton Univ., Njoro (Kenya). Dept. of Animal Health

    1998-11-01

    Toxic trace metals have been implicated as a potential cause of recent flamingo kills at Lake Nakuru, Kenya. Chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) have accumulated in the lake sediments as a result of unregulated discharges and because this alkaline lake has no natural outlet. Lesser flamingos (Phoeniconaias minor) at Lake Nakuru feed predominantly on the cyanobacterium Spirulina platensis, and because of their filter-feeding mechanism, they are susceptible to exposure to particle-bound metals. Trace metal adsorption isotherms to lake sediments and S. platensis were obtained under simulated lake conditions, and a mathematical model was developed to predict metal exposure via filter feeding based on predicted trace metal phase distribution. Metal adsorption to suspended solids followed the trend Pb {much_gt} Zn > Cr > Cu, and isotherms were linear up to 60 {micro}g/L. Adsorption to S. platensis cells followed the trend Pb {much_gt} Zn > Cu > Cr and fit Langmuir isotherms for Cr, Cu and Zn and a linear isotherm for Pb. Predicted phase distributions indicated that Cr and Pb in Lake Nakuru are predominantly associated with suspended solids, whereas Cu and Zn are distributed more evenly between the dissolved phase and particulate phases of both S. platensis and suspended solids. Based on established flamingo feeding rates and particle size selection, predicted Cr and Pb exposure occurs predominantly through ingestion of suspended solids, whereas Cu and Zn exposure occurs through ingestion of both suspended solids and S. platensis. For the lake conditions at the time of sampling, predicted ingestion rates based on measured metal concentrations in lake suspended solids were 0.71, 6.2, 0.81, and 13 mg/kg-d for Cr, Cu, Pb, and Zn, respectively.

  11. A modelling exercise on the importance of ternary alkaline earth carbonate species of uranium(VI) in the inorganic speciation of natural waters

    International Nuclear Information System (INIS)

    Highlights: • The U(VI) speciation in natural waters has been modelled through a modelling exercise. • The results evidence the importance of alkaline earth U(VI) carbonate complexes. • Possible solubility-controlling phases were reported and discussed. • The differences were related to the choice and reliability of thermodynamic data. • Databases need to be improved for reliable U(VI) speciation calculations. - Abstract: Predictive modelling of uranium speciation in natural waters can be achieved using equilibrium thermodynamic data and adequate speciation software. The reliability of such calculations is highly dependent on the equilibrium reactions that are considered as entry data, and the values chosen for the equilibrium constants. The working group “Speciation” of the CETAMA (Analytical methods establishment committee of the French Atomic Energy commission, CEA) has organized a modelling exercise, including four participants, in order to compare modellers’ selections of data and test thermodynamic data bases regarding the calculation of U(VI) inorganic speciation. Six different compositions of model waters were chosen so that to check the importance of ternary alkaline earth carbonate species of U(VI) on the aqueous speciation, and the possible uranium solid phases as solubility-limiting phases. The comparison of the results from the participants suggests (i) that it would be highly valuable for end-users to review thermodynamic constants of ternary carbonate species of U(VI) in a consistent way and implement them in available speciation data bases, and (ii) stresses the necessary care when using data bases to avoid biases and possible erroneous calculations

  12. Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

    Science.gov (United States)

    Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

    2013-11-21

    NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times. PMID:24096887

  13. Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions. Sorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, H.; Garcia-Gutierrez, M.; Missana, T. [CIEMAT, Madrid (Spain). Sorption, Migration and Colloids Lab.; Tits, J.; Wieland, E. [Paul Scherrer Institut, Villigen (Switzerland). Lab. for Waste Management; Gaona, X. [Karlsruhe Institute of Technology, Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung

    2013-05-01

    The complexation of Np(IV) with gluconic acid (GLU) under alkaline conditions was investigated in the absence of Ca by carrying out a series of sorption experiments. The decrease of Np(IV) sorption on the sorbing material at increasing concentrations of GLU was interpreted as the formation of Np(IV)-GLU aqueous complexes. The modelling of experimental data according to the Schubert method [1] confirmed the formation of a complex with a Np:GLU ratio 1: 1. The stoichiometry of the complex Np(OH){sub 4}GLU{sup -} was proposed based on the experimental observation that no proton exchange occurred during the course of the complexation reaction and that Np(OH){sub 4}(aq) was the predominant hydrolysis product in the absence of GLU. A log *{beta}{sup 0}{sub 1,4,1} = -2.92 {+-} 0.30 for the formation reaction Np{sup 4+} + 4H{sub 2}O + GLU{sup -} <=> Np(OH){sub 4}GLU{sup -} + 4H{sup +} was calculated based on the conditional stability constants determined from sorption experiments and using the Np(IV) thermodynamic data selected in the NEA reviews [2]. Linear free energy relationships (LFER) confirmed that the stoichiometry and stability of the Np(IV)-GLU complex characterized in this work are consistent with data available for Th(IV)-, U(IV)- and Pu(IV)-GLU complexes. (orig.)

  14. Evolution of soil properties and metals in acid and alkaline mine tailing ponds after amendments and microorganisms application

    Science.gov (United States)

    Acosta, Jose A.; Faz, Ángel; Zornoza, Raúl; Martínez-Martínez, Silvia; Bech, Jaume

    2015-04-01

    organic carbon, total nitrogen, total phosphorus, potassium, total, bioextractable and soluble metals (Pb, Cu, Zn, As and Cd), basal respiration and microbial biomass carbon; and metals (Pb, Cu, Zn, As and Cd) in roots and shoot from Zygophylum fabago were analyzed. The results showed that the lime increased the concentration of inorganic carbon in both ponds and, therefore, increases the pH until neutral/alkaline values, especially in the acid mine pond, reducing the risk of mobility of As, Pb and Zn to the trophic chain and the risk of leaching and runoff. The application of pig manure increased the salinity in the acid mine pond, as well as the content of OC, TN, K and P in both ponds; also it caused a higher concentration of bioavailable and soluble Cu in both ponds due to the high content of Cu in the manure; finally, an higher concentration of bioavailable and soluble As was observed in the alkaline mine pond due to the formation of organic-metal complexes. The application of sewage sludge increased the content of OC and K in both mine ponds; also it caused an increase in the concentration of bioavailable and water soluble As and a slight increase in the water soluble Cu in the alkaline mine pond likely because of the formation of organic-metal complexes. Both organic amendments increased the microbial biomass carbon (MBC), especially pig manure, indicating that this amendment brings more amount of microorganisms than sewage sludge. Similarly, the application of EM increases MBC, especially in doses 2 and 3, improving soil conditions which favour plant colonization. Furthermore, microbial activity is increased after amendments and EM applications, especially when pig manure was used; indicating that organic matter from pig manure is more easily degradable by microorganisms than organic matter from sewage sludge. Finally, the results indicated that the application of EM promotes the absorption and subsequent translocation to leaves of Cu and As, while prevents the

  15. Relativistic energy levels and oscillator strengths for the ns(n-1)d 1D-ns21S transitions of the alkaline earth atoms

    International Nuclear Information System (INIS)

    A fully relativistic Dirac-Fock method with Breit and QED corrections has been employed to study energy levels and oscillator strengths for the ns(n-1)d 1D-ns21S transitions of the alkaline earth atoms. In calculation, the authors consider significant Breit and QED corrections, the results are in good agreements with recent experimental data and other theoretical values. The results show that it is feasible to obtain the highly Rybderg states of the alkaline earth atoms, especially the autoionization states, by use of quadrupole transitions as an intermediate resonance

  16. Spectroscopy and interactions of metal and metal cation complexes

    OpenAIRE

    Plowright, Richard J.

    2010-01-01

    The work in this thesis looks at the spectroscopy and interactions of metals and metal cation complexes. There are two aspects of this vast subject that are considered: the electronic spectroscopy of Au-RG complexes and the ion-molecule chemistry of metals important in the mesosphere-lower thermosphere (MLT) region of the atmosphere. The spectroscopy of the molecular states in the vicinity of the strong Au 2P3/2, 1/2 ← 2S1/2 atomic transition, have been studied for the Au-RG (RG = Ne, Ar...

  17. Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite for methanol synthesis

    Science.gov (United States)

    Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

    1993-01-01

    The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

  18. Quantum mechanical study of molecular collisions at ultra-low energy: applications to alkali and alkaline-earth systems

    International Nuclear Information System (INIS)

    In order to investigate the collisional processes which occur during the formation of molecular Bose-Einstein condensates, a time-independent quantum mechanical formalism, based on hyperspherical coordinates, has been applied to the study of atom-diatom dynamics at ultra-low energies. We present theoretical results for three alkali systems, each composed of lithium, sodium or potassium atoms, and for an alkaline-earth system composed of calcium atoms. We also study dynamics at large and positive atom-atom scattering length. Evidence for the suppression of inelastic processes in a fermionic system is given, as well as a linear relation between the atom-diatom scattering length and the atom-atom scattering length. (author)

  19. Alkaline earth lead and tin compounds Ae2Pb, Ae2Sn, Ae = Ca, Sr, Ba, as thermoelectric materials

    Directory of Open Access Journals (Sweden)

    David Parker and David J Singh

    2013-01-01

    Full Text Available We present a detailed theoretical study of three alkaline earth compounds Ca2Pb, Sr2Pb and Ba2Pb, which have undergone little previous study, calculating electronic band structures and Boltzmann transport and bulk moduli using density functional theory. We also study the corresponding tin compounds Ca2Sn, Sr2Sn and Ba2Sn. We find that these are all narrow band gap semiconductors with an electronic structure favorable for thermoelectric performance, with substantial thermopowers for the lead compounds at temperature ranges from 300 to 800 K. For the lead compounds, we further find very low calculated bulk moduli—roughly half of the values for the lead chalcogenides, suggestive of soft phonons and hence low lattice thermal conductivity. All these facts indicate that these materials merit experimental investigation as potential high performance thermoelectrics. We find good potential for thermoelectric performance in the environmentally friendly stannide materials, particularly at high temperature.

  20. Optical Feshbach resonances of Alkaline-Earth atoms in a 1D or 2D optical lattice

    CERN Document Server

    Naidon, P; Julienne, Paul S.; Naidon, Pascal

    2006-01-01

    Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96, 203201], we present the theory for photoassociation and optical Feshbach resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional (2D) optical lattice. In the case of an alkaline-earth intercombination resonance, the narrow natural width of the line makes it possible to observe clear manifestations of the dimensionality, as well as some sensitivity to the scattering length of the atoms. Among possible applications, a 2D lattice may be used to increase the spectroscopic resolution by about one order of magnitude. Furthermore, a 1D lattice induces a shift which provides a new way of determining the strength of a resonance by spectroscopic measurements.

  1. Brief introduction to the geology of the Ilimaussaq alkaline complex, South Greenland, and its exploration history

    International Nuclear Information System (INIS)

    The Ilimaussaq alkaline complex, the type locality of agpaitic nepheline syenites, is made up of three intrusive phases, 1) augite syenite, 2) alkali acid rocks and 3) agpaitic nepheline syenites which occupy the major part of the complex. The agpaitic phase comprises a roof series, a floor series and an intermediate sequence of rocks. The roof series crystallised from the roof downwards beginning with non-agpaitic pulaskite and ending with distinctly agpaitic naujaite. The exposed part of the floor series is made up of the layered agpaitic nepheline syenite kakortokite. The intermediate sequence consists of several types of distinctly agpaitic lujavrites which are accompanied by occurrences of uranium and other rare elements. The complex was first visited by K.L. Giesecke in 1806 and 1809. The first detailed mapping of the complex was carried out by N.V. Ussing in 1900 and 1908. He presented a precise description of the major rock types and an illuminating discussion of the petrology of the complex in his 1912 memoir. In the period 1912-1955 there was very limited activity in the complex. Exploration for radioactive minerals in Ilimaussaq was initiated in 1955 and in subsequent years followed by geological mapping carried out by the Geological Survey of Greenland. This led to a series of detailed studies of the occurrences of not only U, but also Be, Nb, REE and Zr, and to mineralogical, geochemical and petrological studies as well as commercial evaluation and drilling. (au)

  2. Decomposition kinetics of alkaline earth carbonates by integral approximation method Cinética de decomposição de carbonatos de terra alcalina pelo método de aproximação integral

    OpenAIRE

    S Maitra; Chakrabarty, N.; Pramanik, J.

    2008-01-01

    The decomposition kinetics of four synthetic alkaline earth metal carbonates (MgCO3, CaCO3, SrCO3 and BaCO3) was studied under non-isothermal conditions from thermo-gravimetric measurements as compared to. The integral approximation method of Coats and Redfern was used to determine the kinetic parameters for the decomposition processes. The decomposition reactions followed mostly first order kinetics and the activation energy of the decomposition reactions increased with the increase in the m...

  3. Characterization of alkaline-earth oxide additions to the MnO2 cathode in an aqueous secondary battery

    International Nuclear Information System (INIS)

    Highlights: → Adding MgO in MnO2 cathode enhances the battery discharge capacity. → Mechanism appears to be different with those of our previously published results. → Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. → Transferred the primary battery into a secondary while using LiOH as electrolyte. - Abstract: The effect of alkaline-earth oxide additions on aqueous rechargeable battery is investigated using microscopic and spectroscopic techniques. The alkaline-earth oxide additions such as magnesium oxide (MgO) and barium oxide (BaO) were physically mixed to the manganese dioxide (MnO2) cathode of a cell comprising zinc as an anode and aqueous lithium hydroxide as the electrolyte. The results showed that such additions greatly improved the discharge capacity of the battery (from 145 to 195 for MgO and 265 mAh/g for BaO). Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. With an aim to understand the role of these additives and its improvement in cell performance, we have used microscopy, spectroscopy, ion beam analysis and diffraction based techniques to study the process. Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy analysis (EDS) results showed evidence of crystalline MnO2 particles for MgO as additive, whereas, MnO2 particles with diffused structure leading to mixture of phases is observed for BaO additives which is in agreement with X-ray diffraction (XRD) data. This work relates to improvement in the electrochemical behaviour of the Zn-MnO2 battery while the MgO additive helps to reduce the formation of manganese and zinc such as hetaerolite that hinders the lithium intercalation.

  4. Sm3+-doped alkaline earth borate glasses as UV→visible photon conversion layer for solar cells

    International Nuclear Information System (INIS)

    Intense multi-peak red fluorescence emissions of Sm3+ are exhibited in alkaline-earth borate (LKZBSB) glasses under UV radiation. The spontaneous emission probabilities Arad corresponding to the 4G5/2→6HJ (J=5/2, 7/2, 9/2 and 11/2) transitions are derived to be 24.74, 129.72, 117.03 and 32.23 s−1, respectively, and the relevant stimulated emission cross-sections σem are 0.77×10−22, 4.46×10−22, 5.05×10−22 and 1.38×10−22 cm2, confirming the effectiveness of red luminescence in Sm3+-doped LKZBSB glasses. Quantitative characterization through the evaluation of absolute spectral parameters reveals that the quantum yield of Sm3+-doped LKZBSB glasses is as high as 13.29%. Furthermore, with the introduction of Ce3+, the effective excitation wavelength range and the emission intensity of Sm3+ in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of 9.02 in the UVB region. These results demonstrate that the present glass system has promising potential as an efficient UV→visible photon conversion layer for the enhancement of solar cell efficiency, including appealing applications in outer space. - Highlights: • Intense multi-peak red fluorescence emissions of Sm3+ are exhibited under UV radiation. • Effectiveness of red luminescence is confirmed by stimulated emission cross-sections. • Quantum yield of Sm3+-doped LKZBSB glasses is 13.29% by quantitative characterization. • Effective excitation wavelength range and emission intensity are improved with Ce3+ doping. • Alkaline-earth borate glass has potential as solar cell UV→Vis photon conversion layer

  5. Influence of alkali and alkaline earth elements on the uptake of radionuclides by Pleurototus eryngii fruit bodies

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, J., E-mail: fguillen@unex.es [LARUEX, Dpt. Applied Physics, Faculty of Veterinary Science, University of Extremadura, Avda. Universidad, s/n, 10071 Caceres (Spain); Baeza, A.; Salas, A. [LARUEX, Dpt. Applied Physics, Faculty of Veterinary Science, University of Extremadura, Avda. Universidad, s/n, 10071 Caceres (Spain)

    2012-04-15

    In the literature, there are many data available on radionuclide contents and their transfer to different species of mushrooms. There are some variables, however, which affect the transfer but are very difficult to observe in collected wild mushrooms. An example is the effect of different concentrations of alkali and alkaline earth elements in the soil. Modification of these concentrations in the soil solution has traditionally been used as a countermeasure to deal with radioactively contaminated areas. In the present work, fruiting bodies of Pleurotus eryngii, a saprophytic mushroom, were grown under controlled laboratory conditions, varying the content of alkali (potassium and caesium) and alkaline earth (calcium and strontium) elements. The transfer of {sup 134}Cs, {sup 85}Sr, and {sup 60}Co (added to the cultures) and of natural {sup 210}Pb was analysed by increasing the content of each stable element considered. A significant, but nonlinear, enhancement of stable caesium and {sup 134}Cs was observed with increasing content of stable caesium in the substrate/mycelium. The transfer of {sup 85}Sr decreased with the addition of each stable cation, whereas the {sup 60}Co and {sup 210}Pb transfers were unaffected. - Highlights: Black-Right-Pointing-Pointer The addition of stable potassium did not affect the uptake of radiocaesium. Black-Right-Pointing-Pointer The addition of stable caesium increased the stable caesium and {sup 134}Cs content in the fruiting bodies of Pleurotus eryngii. Black-Right-Pointing-Pointer The addition of calcium reduced the content of calcium and {sup 85}Sr in the fruiting bodies. Black-Right-Pointing-Pointer These countermeasures did not work properly in the case of {sup 60}Co and {sup 210}Pb, no effect was observed.

  6. Rare Earth Metal/semiconductor Interfaces and Compounds

    Science.gov (United States)

    Nogami, Jun

    Interfaces formed at room temperature by incremental deposition of rare earth metals onto semiconductor substrates have been studied with surface sensitive soft X-ray photoelectron spectroscopy. The trends in core level lineshape and intensity with increasing metal coverage have been used to deduce an outline of the evolution and the final morphology of the interfacial region on a microscopic scale. Measurements were taken for Ytterbium (Yb) on Silicon (Si), Germanium, and Gallium Arsenide, and for Gadolinium (Gd) and Europium (Eu) on Silicon. The Yb/Si interface work was supported by comparable measurements of bulk Yb silicide samples of known composition and crystal structure. In a general sense, the behavior of all the systems studied is similar. At very low metal coverages, the metal atoms chemisorb and are weakly bonded to the substrate. The 4f core levels indicate that the metal-metal atom coordination is relatively low at this stage. The interaction with the substrate strengthens with increasing coverage, culminating in the formation of a strongly reacted phase at between 1 and 3 monolayers (ML). The strong reaction is limited to a narrow region at room temperature. At less than 10 ML coverage, the surface of the sample is almost indistinguishable from the pure metal. Details of the behavior such as the reactivity at low coverage, the compounds formed at the interface, the morphology at the surface at intermediate coverages, the final interfacial width, and the amount of substrate atom outdiffusion and surface segregation can all vary from system to system. It is in explaining the causes of some of these differences that insight about what governs the behavior of all of these rare earth metal/semiconductor systems has been obtained. The divalent metals (Yb, Eu) are significantly less reactive than trivalent Gd at sub-monolayer coverages. For the divalent metals the formation of a metal-rich phase is strongly favored in the reaction at the interface, whereas

  7. Rare earth metal oxides as BH4-tolerance cathode electrocatalysts for direct borohydride fuel cells

    Institute of Scientific and Technical Information of China (English)

    NI Xuemin; WANG Yadong; GUO Feng; YAO Pei; PAN Mu

    2012-01-01

    Rare earth metal oxides (REMO) as cathode electrocatalysts in direct borohydride fuel cell (DBFC) were investigated.The REMO electrocatalysts tested showed favorable activity to the oxygen electro-reduction reaction and strong tolerance to the attack of BH4- in alkaline electrolytes.The simple membraneless DBFCs using REMO as cathode electrocatalyst and using hydrogen storage alloy as anodic electrocatalyst exhibited an open circuit of about 1 V and peak power of above 60 mW/cm2.The DBFC using Sm2O3 as cathode electrocatalyst showed a relatively better performance.The maximal power density of 76.2 mW/cm2 was obtained at the cell voltage of 0.52 V.

  8. Suitable alkaline for graphene peeling grown on metallic catalysts using chemical vapor deposition

    Science.gov (United States)

    Karamat, S.; Sonuşen, S.; Çelik, Ü.; Uysallı, Y.; Oral, A.

    2016-04-01

    In chemical vapor deposition, the higher growth temperature roughens the surface of the metal catalyst and a delicate method is necessary for the transfer of graphene from metal catalyst to the desired substrates. In this work, we grow graphene on Pt and Cu foil via ambient pressure chemical vapor deposition (AP-CVD) method and further alkaline water electrolysis was used to peel off graphene from the metallic catalyst. We used different electrolytes i.e., sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH) and barium hydroxide Ba(OH)2 for electrolysis, hydrogen bubbles evolved at the Pt cathode (graphene/Pt/PMMA stack) and as a result graphene layer peeled off from the substrate without damage. The peeling time for KOH and LiOH was ∼6 min and for NaOH and Ba(OH)2 it was ∼15 min. KOH and LiOH peeled off graphene very efficiently as compared to NaOH and Ba(OH)2 from the Pt electrode. In case of copper, the peeling time is ∼3-5 min. Different characterizations like optical microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy were done to analyze the as grown and transferred graphene samples.

  9. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  10. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  11. Metal complexes with paramagnetic thiosemicarbazone

    International Nuclear Information System (INIS)

    The complexes of Ni(2), Fe(2), Zn(2), Cd(2), Pd(2) and Pt(2) with the stable nitroxyl radical of thiosemicarbazone 4-formyl- 2, 2, 5, 5-tetramethyl-3-imidazoline-1-oxyl of the composition ML2 are synthesized. In the basis of the data of physical methods (IR, EPR, electron spectroscopy) a conclusion is made on the way of the ligand coordination. The study of the magnetic properties of the complexes has shown that in the compounds prepared a weak exchange interaction between unpaired electrons of paramagnetic centres takes place

  12. Recovery of rare earth metals through biosorption:An overview

    Institute of Scientific and Technical Information of China (English)

    Nilanjana Das; Devlina Das

    2013-01-01

    Rare earth metals (REMs) are a series of 17 elements that have widespread and unique applications in high technology, power generation, communications, and defense industries. These resources are also pivotal to emergent sustainable energy and car-bon alternative technologies. Recovery of REMs is interesting due to its high market prices along with various industrial applications. Conventional technologies, viz. precipitation, filtration, liquid-liquid extraction, solid-liquid extraction, ion exchange, super critical extraction, electrowinning, electrorefining, electroslag refining, etc., which have been developed for the recovery of REMs, are not economically attractive. Biosorption represents a biotechnological innovation as well as a cost effective excellent tool for the recovery of rare earth metals from aqueous solutions. A variety of biomaterials such as algae, fungi, bacteria, resin, activated carbon, etc., have been reported to serve as potential adsorbents for the recovery of REMs. The metal binding mechanisms, as well as the parameters in-fluencing the uptake of rare earth metals and isotherm modeling are presented here. This article provides an overview of past achievements and current scenario of the biosorption studies carried out using some promising biosorbents which could serve as an economical means for recovering REMs. The experimental findings reported by different workers will provide insights into this re-search frontier.

  13. Effects of alternating current imposition and alkaline earth elements on modification of primary Mg_2Si crystals in hypereutectic Mg-Si alloy

    Institute of Scientific and Technical Information of China (English)

    DU Jun; K. IWAI; LI Wen-fang; PENG Ji-hua

    2009-01-01

    The effects of alternating current imposition and/or alkaline earth elements on modification of the primary Mg_2Si crystals in the hypereutectic Mg-Si alloy were investigated. An alternating current of 60 A with frequency of 1 kHz was applied into the hypereutectic Mg-Si melt which was alloyed with alkaline earth elements or not in the fixed temperature range from 700 to 630 ℃. The results show that the primary Mg_2Si crystals could be refined by imposing alternating current or adding alkaline elements. Compared with the samples treated by adding 0.4% Ca or 0.4% Sr, higher modification efficiency could be obtained for the samples treated by imposing alternating current. No further modification efficiency could be obtained for the samples treated by imposing alternating current combined with 0.4% Ca or 0.4% Sr addition.

  14. Comparative distributions of alkalies, alkaline earths and lead among major tissues of the tuna Thunnus alalunga

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, C.; Settle, D.

    1977-01-01

    The occurrences of K, Rb, Cs, Ca, Sr, Ba and Pb have been determined in various tissues of the tuna fish Thunnus alalunga. K, Rb, and Cs are distributed uniformly throughout the organs of the fish; 95 percent of the Ca and Sr, and 70 percent of the Ba and Pb are contained in the skeleton. It is found that there are smaller amounts of Cs, Ba and Pb associated with the nutrient metals K and Ca in a marine animal compared to a terrestrial animal. This difference is a result of the purity of K and Ca in seawater and the smaller amounts of trace metals associated with them compared to the impurity of K and Ca in terrestrial rocks. Food-chain enhancement and depletion of metals can be evaluated by comparing ratios of trace metals to abundant nutrient metals in seawater and tuna. Cs in enriched relative to K in going from seawater to tuna by a factor of 13. Sr and Ba are both depleted by factors of 5 relative to Ca in going from seawater to tuna, while Pb is enriched relative to Ca by a factor of 14. Special clean laboratory procedures were used to prepare samples for accurate analysis by stable isotope dilution mass spectrometric techniques.

  15. An Alkaline-Stable, Metal Hydroxide Mimicking Metal-Organic Framework for Efficient Electrocatalytic Oxygen Evolution.

    Science.gov (United States)

    Lu, Xue-Feng; Liao, Pei-Qin; Wang, Jia-Wei; Wu, Jun-Xi; Chen, Xun-Wei; He, Chun-Ting; Zhang, Jie-Peng; Li, Gao-Ren; Chen, Xiao-Ming

    2016-07-13

    Postsynthetic ion exchange of [Co2(μ-Cl)2(btta)] (MAF-X27-Cl, H2bbta =1H,5H-benzo(1,2-d:4,5-d')bistriazole) possessing open metal sites on its pore surface yields a material [Co2(μ-OH)2(bbta)] (MAF-X27-OH) functionalized by both open metal sites and hydroxide ligands, giving drastically improved electrocatalytic activities for the oxygen evolution reaction (an overpotential of 292 mV at 10.0 mA cm(-2) in 1.0 M KOH solution). Isotope tracing experiments further confirm that the hydroxide ligands are involved in the OER process to provide a low-energy intraframework coupling pathway. PMID:27356078

  16. Electronic Structure of Rare-Earth Metals. II. Positron Annihilation

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    The angular correlation of the photons emitted when positrons annihilate with electrons has been studied in single crystals of the rare-earth metals Y, Gd, Tb, Dy, Ho, and Er, and in a single crystal of an equiatomic alloy of Ho and Er. A comparison of the results for Y with the calculations...... of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood...... qualitatively in terms of the relativistic augmented-plane-wave calculations by Keeton and Loucks. The angular distributions in the c direction in the paramagnetic phases are characterized by a rapid drop at low angles followed by a hump, and these features are associated with rather flat regions of Fermi...

  17. Microstructural characterisation of epitaxial rare earth metal based films

    International Nuclear Information System (INIS)

    Epitaxial rare earth films and superlattices grown by molecular beam epitaxy, MBE, can be designed to investigate theoretical predictions of the magnetic and electronic properties of the metals. These investigations ideally require smooth epitaxial layers with atomically flat interfaces and therefore the microstructure of selected epitaxial rare earth systems has been characterised by a combination of techniques. These systems were grown on a (110) niobium parallel (112-bar0) sapphire substrate. Because the crystallographic quality of the subsequent layers is influenced by the quality of the substrate, the niobium-sapphire interface was studied with transmission electron microscopy, TEM, and high resolution electron microscopy, HREM, to identify uniquely the misfit dislocation network. Conventional TEM specimen preparation techniques were inappropriate for the preparation of metallic foils, and so appropriate specimen preparation techniques were developed. HREM was used to characterise the strain relief mechanisms within a partially relaxed holmium/yttrium superlattice

  18. Emplacement of Amba Dongar Carbonatite-alkaline Complex at Cretaceous/Tertiary Boundary: Evidence from 40Ar-39Ar Chronology

    Indian Academy of Sciences (India)

    Jyotiranjan S Ray; Kanchan Pande; T R Venkatesan

    2000-03-01

    40Ar-39Ar analyses of three fresh alkaline rock samples and a phlogopite separate from a carbonatite from Amba Dongar carbonatite-alkaline complex of the Deccan Flood Basalt Province, India, yield indistinguishable precise plateau ages of 64.8 ± 0.6, 64.7 ± 0.5, 65.5 ± 0.8 and 65.3 ± 0.6 Ma, giving a mean plateau age of 65.0 ± 0.3 Ma, which is the age of emplacement of this complex. This age implies contemporaneity of Amba Dongar with several other carbonatite-alkaline activities of Chhota Udaipur subprovince and is consistent with their Reunion-Deccan plume origin hypothesis. The emplacement of these complexes at 65 Ma makes them very significant in the ongoing debate on the K/T extinctions owing to their capacity to rapidly inject a substantial amount of CO2 and SO2 into the atmosphere.

  19. Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

    Science.gov (United States)

    Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

    2016-08-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba

  20. Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

    Science.gov (United States)

    Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

    2016-08-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Bacontaining copper dopants.

  1. Design of a novel optically stimulated luminescent dosimeter using alkaline earth sulfides doped with SrS:Eu,Sm materials

    Institute of Scientific and Technical Information of China (English)

    Yanping Liu; Zhaoyang Chen; Yanwei Fan; Weizhen Ba; Wu Lu; Qi Guo; Shilie Pan; Aimin Chang; Xinqiang Tang

    2008-01-01

    Optically stimulated luminescence (OSL) is the luminescence emitted from an irradiated insulator or semiconductor during exposure to light.The OSL intensity is a function of the dose of radiation absorbed by the sample and thus can be used as the basis of a radiation dosimetry method.Alkaline earth sulfides doped with rare-earth elements such as Ce,Sm and Eu are OSL dosimeters having very high sensitivity,and the OSL with a short time constant is separated from the stimulated light.In this paper,a novel OSL dosimeter designed with SrS:Eu,Sm materials is described.The dosimeter takes advantage of the characteristics of charge trapping materials SrS:Eu,Sm that exhibit OSL.The measuring range of the dosimeter is from 0.01 to 100Gy.The equipment,which is relatively simple and small in size,is promising for applications in space exploration and high dose radiation dosimetry.

  2. Metal plasmon enhanced europium complex luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Liu Feng [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Aldea, Gabriela [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Petru Poni Institute of Macromolecular Chemistry Iasi, Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Nunzi, Jean-Michel, E-mail: nunzijm@queensu.c [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada)

    2010-01-15

    The plasmon enhanced luminescence of a rare-earth complex Tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (Eu(fod){sub 3}) was investigated. A polyvinyl alcohol (PVA) thin film was successfully adopted as a spacer to separate the Eu complex from the silver island film (SIF), and five-fold enhancement of the radiative decay rate of the Eu complex on SIF was demonstrated based on the luminescence intensity and lifetime measurement. Investigation of the distance dependent luminescence indicates that 7 nm is an optimal distance for SIF enhanced Eu luminescence. Plasmon enhanced rare-earth luminescence based on an organic film spacer would find potential applications in plasmon enhanced organic light emitting diode (OLED) devices.

  3. Comparison of Carboxylic and Hydroxycarboxylic Acids as Complexing Agents for Transition Metal Separation with Nonaqueous Capillary Electrophoresis%非水毛细管电泳分离过渡金属羧酸和羟基羧酸配位剂的比较

    Institute of Scientific and Technical Information of China (English)

    屈锋; 林金明

    2004-01-01

    @@ Many papers have been published on the analysis of metal cations by capillary electrophoresis (CE), for example, lanthanide, transition metal, alkali, and alkaline earth metal ions. Separations of metal ions are based on the differences in their electrophoretic mobilities. Since most metal ions having identical charge and size give rise to identical electrophoretic mobilities, the direct electrophoretic separation of these ions is impossible. However, their mobilities can be modified by introducing chemical equilibria in which the ions are involved in forming complexes. If metal ions have different complex formation constants, their apparent electrophoretic mobilities differ. The separation process is mainly carried out by using various weak complexing agents[1-4], which complex the metal ions to different extents. The weak complexing agents for metal ion separation primarily are hydroxycarboxylic acids with hydroxyl and carboxyl groups. In addition, organic solvents have also been added into the electrolytes to improve the selectivity of metal ion separation. When a metal ion interacts with polar solvent molecules through ion-dipole bonds, a solvation shell may be formed around the central ion. In principle, the solvent solvates all kinds of ions in solution, some to a greater extent than others, depending on the specific properties of the central ion regarding a certain solvent. The use of pure nonaqueous systems offers potential for adjustment of relative migration rates via changes in solvent-ion interaction. Evidence for such analyte-electrolyte interaction has been reported for the separations of inorganic anions[5] and alkali, alkaline earth and transition metal ions in pure nonaqueous systems[6-8].

  4. On the complex structural diffusion of proton holes in nanoconfined alkaline solutions within slit pores.

    Science.gov (United States)

    Muñoz-Santiburcio, Daniel; Marx, Dominik

    2016-01-01

    The hydroxide anion OH(-)(aq) in homogeneous bulk water, that is, the solvated proton hole, is known to feature peculiar properties compared with excess protons solvated therein. In this work, it is disclosed that nanoconfinement of such alkaline aqueous solutions strongly affects the key structural and dynamical properties of OH(-)(aq) compared with the bulk limit. The combined effect of the preferred hypercoordinated solvation pattern of OH(-)(aq), its preferred perpendicular orientation relative to the confining surfaces, the pronounced layering of nanoconfined water and the topology of the hydrogen bond network required for proton hole transfer lead to major changes of the charge transport mechanism, in such a way that the proton hole migration mechanism depends exquisitely on the width of the confined space that hosts the water film. Moreover, the anionic Zundel complex, which is of transient nature in homogeneous bulk solutions, can be dynamically trapped as a shallow intermediate species by suitable nanoconfinement conditions. PMID:27550616

  5. A reflection seismic study of the Alnö alkaline and carbonatite igneous complex

    Science.gov (United States)

    Andersson, M.; Malehmir, A.; Dehghannejad, M.; Troll, V. R.; Ask, M.

    2012-04-01

    The Alnö igneous complex in central Sweden is one of the largest (about 5 km by 5 km) of the few well-known alkaline and carbonatite intrusions in the world. It contains a wide variety of lithologies, including alkaline silicate igneous rocks (Ijolite, Nephelinesyenite, and Pyroxenite) and a range of carbonatite dykes with a variable composition (Kresten, 1990). Alnö island is the type locality for Alnöite, a melilite-bearing basic rock that occurs as dykes and contains a complex mineral assemblage with phenocrysts from the deep crust and the upper mantle. Geochronological measurements suggest an age of 553-590 Ma for the main intrusion. The depth extent, dip and dip direction of the carbonatite rocks have been inferred from surface geological mapping, but lack depth-constraints. Our research aims to improve understanding of the intrusion mechanism(s) and the geometry of the Alnö intrusion and through that of alkaline and carbonatite intrusions in general. We have acquired three high-resolution reflection seismic profiles over the main intrusion during winter 2011. Densely sampled surface gravity and magnetic data were also collected along the seismic profiles and on the sea-ice with gravity measurements indicating a strong positive Bouguer anomaly of about 20 mGal over the main intrusion. Petrophysical measurements including compressional- and shear-wave velocities, anisotropy of magnetic susceptibility (AMS), and density data were gathered from oriented samples of representative lithologies. For the seismic data, nearly 400 active channels were employed with a geophone spacing of 10 meters. A mechanical hammer was used for generating the seismic waves and was activated at most geophone positions. Since the acquisition took part in winter, we also extended the profiles out on the sea-ice close to the shore. The geophones were planted in the frozen ground/ice and covered by snow resulting in improved signal-to-noise ratios. The main profile is about 10 km long

  6. Petrology, geochemistry and geochonology of the Jacupiranga ultramafic, alkaline and carbonatitic complex (southern Brazil)

    Science.gov (United States)

    Chmyz, Luanna; Arnaud, Nicolas; Biondi, João Carlos

    2015-04-01

    Brazilian carbonatitic complexes are located at the edges of the Paleozoic basins and are usually associated to tectonic crustal flexuring or deep fault zones. The Jacupiranga Complex is a 65 km² ultrabasic-alkaline carbonatitic intrusive body outcroping at the northeastern border of the Paraná Basin, South of São Paulo State (Brazil). The northern portion of the unit is mostly composed of peridotitic rocks, while the southern part contains ijolites, melteigites, clinopyroxenites and carbonatites which host a phosphate deposit, mined since 1966. Even though the carbonatites only represent 1% of the Complex's area, they have concentrated most of the historical petrogenetic studies, leaving almost unknown the petrogenetic and the geochronological characteristics of other rocks. This explains why the few petrogenetic models from the literature are very partial and mostly unsatisfactory. While the peridotitic rocks are largely hindered by the absence of fresh outcrops, the regolith thickness and the high serpentinization degree, field observations and petrographic data notably show a heterogeneous zone around the peridotitic body. That zone is composed of a large variety of lithotypes over a relatively small area (~9 km²), comprising diorites, monzodiorites, alkali feldspar syenites, trachytes, lamprophyres and syenites. Moreover, these rocks present a restricted lateral continuity (decametric) and a lack of the magmatic bedding characteristic of the ijolitic and clinopyroxenitc rocks. The southern clinopyroxenitic zone (~20 km²) is composed of clinopyroxenite and melteigite with prominent magmatic layering, probably of cumulative origin, and a body of carbonatites which outcrops over less than 1 km2 essentially composed of sovite and beforsite, with abundant apatite. The Jacupiranga Complex characteristics indicate that its formation possibly comprises at least five magmatic events which cannot at present be surely ordinated in time: a) the emplacement of the

  7. Syntheses of new rare earth complexes with carboxymethylated polysaccharides and evaluation of their in vitro antifungal activities.

    Science.gov (United States)

    Sun, Xiaobo; Jin, Xiaozhe; Pan, Wei; Wang, Jinping

    2014-11-26

    In the present paper, La, Eu and Yb were selected to represent light, middle and heavy rare earths to form complexes with polysaccharides through chelating coordination of carboxyl groups, which were added into polysaccharide chains by means of carboxymethylation. Their antifungal activities against plant pathogenic fungi were evaluated using growth rate method. These rare earth complexes exhibited various antifungal activities against the tested fungi, depending on rare earth elements, polysaccharide types and fungal species. Among these three metal elements (i.e. La, Eu and Yb), Yb formed the complexes with the most effective antifungal properties. Furthermore, the results showed that ligands of carboxymethylated polysaccharides played a key role in promoting cytotoxicity of the rare earth complexes. Carboxymethylated Ganoderma applanatum polysaccharide (CGAP) was found to be the most effective ligand to form complexes with antifungal activities, followed by carboxymethylated lentinan (CLNT) and carboxymethylated Momordica charantia polysaccharide (CMCP). PMID:25256475

  8. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Stanislaus; Zhang, Fen

    2016-06-28

    The present invention provides a method of producing a crystalline rare earth phosphate nanostructure. The method comprising: providing a rare earth metal precursor solution and providing a phosphate precursor solution; placing a porous membrane between the metal precursor solution and the phosphate precursor solution, wherein metal cations of the metal precursor solution and phosphate ions of the phosphate precursor solution react, thereby producing a crystalline rare earth metal phosphate nanostructure.

  9. Investigation of the Alkaline Electrochemical Interface and Development of Composite Metal/Metal-Oxides for Hydrogen and Oxygen Electrodes

    Science.gov (United States)

    Bates, Michael

    Understanding the fundamentals of electrochemical interfaces will undoubtedly reveal a path forward towards a society based on clean and renewable energy. In particular, it has been proposed that hydrogen can play a major role as an energy carrier of the future. To fully utilize the clean energy potential of a hydrogen economy, it is vital to produce hydrogen via water electrolysis, thus avoiding co-production of CO2 inherent to reformate hydrogen. While significant research efforts elsewhere are focused on photo-chemical hydrogen production from water, the inherent low efficiency of this method would require a massive land-use footprint to achieve sufficient hydrogen production rates to integrate hydrogen into energy markets. Thus, this research has primarily focused on the water splitting reactions on base-metal catalysts in the alkaline environment. Development of high-performance base-metal catalysts will help move alkaline water electrolysis to the forefront of hydrogen production methods, and when paired with solar and wind energy production, represents a clean and renewable energy economy. In addition to the water electrolysis reactions, research was conducted to understand the de-activation of reversible hydrogen electrodes in the corrosive environment of the hydrogen-bromine redox flow battery. Redox flow batteries represent a promising energy storage option to overcome the intermittency challenge of wind and solar energy production methods. Optimization of modular and scalable energy storage technology will allow higher penetration of renewable wind and solar energy into the grid. In Chapter 1, an overview of renewable energy production methods and energy storage options is presented. In addition, the fundamentals of electrochemical analysis and physical characterization of the catalysts are discussed. Chapter 2 reports the development of a Ni-Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline

  10. Thermodynamic parameters and stabilities of some rare-earth metal ion chelates of alpha-valine

    International Nuclear Information System (INIS)

    Solution equilibrium for some rare-earth metal ions with valine have been studied potentiometrically in aqueous medium at temperature from 25 to 55 deg. C and ionic strength from 0.1 to 1.0 mol dm/sup -3/NaClO/sub 4/. The thermodynamic parameters delta H, delta S, delta G for the formation process were evaluated in terms of temperature, ionic strength and nature of metal ion present. The stability of the complexes was found to: La(III)< Nd(III)< Gd(III)< Eu(III)Yb(III)< Lu(III). (author)

  11. Special Issue: Practical Applications of Metal Complexes

    Directory of Open Access Journals (Sweden)

    Iztok Turel

    2015-04-01

    Full Text Available In 1913 Alfred Werner received the Nobel Prize in Chemistry for his work that was of great importance for the development of coordination chemistry. In the years that followed numerous complexes consisting of metal ions and organic ligands were isolated, thus building a strong connection between inorganic and organic chemistry. Coordination compounds have many interesting properties which find diverse applications in numerous aspects of human life. Fourteeen contributions were received for this Special Issue covering very different aspects of metal complexes and their practical applications. The highest number of manuscripts deals with the biological activity of complexes which might potentially be used in the clinical practice. Authors have tested their cytotoxicity, antibacterial activity and enzyme inhibition. Their optical properties were studied in view of their potential use in photodynamic therapy. Moreover, optical properties could also be used for bioanalysis. It is also known that metal complexes are useful catalysts and a few such examples are also described herein. Many other interesting properties and facts about the isolated and described complexes are also reported (radioactivity, design of metal-organic frameworks, etc..

  12. Alkaline sorbent injection for mercury control

    Science.gov (United States)

    Madden, Deborah A.; Holmes, Michael J.

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  13. Sm{sup 3+}-doped alkaline earth borate glasses as UV→visible photon conversion layer for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, L.F. [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Chen, B.J.; Pun, E.Y.B. [Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lin, H., E-mail: lhai8686@yahoo.com [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-04-15

    Intense multi-peak red fluorescence emissions of Sm{sup 3+} are exhibited in alkaline-earth borate (LKZBSB) glasses under UV radiation. The spontaneous emission probabilities A{sub rad} corresponding to the {sup 4}G{sub 5/2}→{sup 6}H{sub J} (J=5/2, 7/2, 9/2 and 11/2) transitions are derived to be 24.74, 129.72, 117.03 and 32.23 s{sup −1}, respectively, and the relevant stimulated emission cross-sections σ{sub em} are 0.77×10{sup −22}, 4.46×10{sup −22}, 5.05×10{sup −22} and 1.38×10{sup −22} cm{sup 2}, confirming the effectiveness of red luminescence in Sm{sup 3+}-doped LKZBSB glasses. Quantitative characterization through the evaluation of absolute spectral parameters reveals that the quantum yield of Sm{sup 3+}-doped LKZBSB glasses is as high as 13.29%. Furthermore, with the introduction of Ce{sup 3+}, the effective excitation wavelength range and the emission intensity of Sm{sup 3+} in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of 9.02 in the UVB region. These results demonstrate that the present glass system has promising potential as an efficient UV→visible photon conversion layer for the enhancement of solar cell efficiency, including appealing applications in outer space. - Highlights: • Intense multi-peak red fluorescence emissions of Sm{sup 3+} are exhibited under UV radiation. • Effectiveness of red luminescence is confirmed by stimulated emission cross-sections. • Quantum yield of Sm{sup 3+}-doped LKZBSB glasses is 13.29% by quantitative characterization. • Effective excitation wavelength range and emission intensity are improved with Ce{sup 3+} doping. • Alkaline-earth borate glass has potential as solar cell UV→Vis photon conversion layer.

  14. Hydrogen storage in complex metal hydrides

    Directory of Open Access Journals (Sweden)

    BORISLAV BOGDANOVIĆ

    2009-02-01

    Full Text Available Complex metal hydrides such as sodium aluminohydride (NaAlH4 and sodium borohydride (NaBH4 are solid-state hydrogen-storage materials with high hydrogen capacities. They can be used in combination with fuel cells as a hydrogen source thus enabling longer operation times compared with classical metal hydrides. The most important point for a wide application of these materials is the reversibility under moderate technical conditions. At present, only NaAlH4 has favourable thermodynamic properties and can be employed as a thermally reversible means of hydrogen storage. By contrast, NaBH4 is a typical non- -reversible complex metal hydride; it reacts with water to produce hydrogen.

  15. The effects of alkaline earth metal ions and halogen ions on the chromium oxide activities in alkaline earth metal oxide-halide-Cr2O3 system fluxes

    Science.gov (United States)

    Li, Lian-Fu; Jiang, Mao-Fa; Wang, Wen-Zhong; Chen, Zhao-Ping

    2000-06-01

    The solid electrolyte cell — Mo|Cr + Cr2O3‖ZrO2(MgO)‖{Cu-Cr}alloy + (Cr2O3)fluxes|Mo+ is used at 1673 K to determine Cr2O3 activities in MO-MX 2-Cr2O3 (M = Ca2+, Ba2-, X = F- or Cl-) ternary fluxes, which are in equilibrium with the copper-chromium binary alloy. The ternary isothermal phase diagrams of CaO-CaF2-Cr2O3 and BaO-BaCl2-Cr2O3 system fluxes are inferred on the basis of the experimental results and binary phase diagrams. The results indicate that Cr2O3 activities in all fluxes always decrease with the increase of the X MO /X MX2 ratio. Partial replacement of BaO in BaO-BaF2-Cr2O3 fluxes by CaO is acceptable for economy and efficiency considerations. At the same time, partial substitution of BaO for CaO in CaO-CaF2-Cr2O3 fluxes is advantageous for phosphorus removal and chromium retention as a result of the increased Cr2O3 activities, increased basicities, and widening of the liquid zones. Compared to those in BaO-BaF2-Cr2O3 fluxes, Cr2O3 activities in CaO-CaF2-Cr2O3 fluxes approximately follow the same curve as the former, although the position and the width of the liquid zones are considerably different, and activities in BaO-BaCl2-Cr2O3 fluxes are higher at the lower Cr2O3 content, or vice versa. The activity coefficients of Cr2O3 in the fluxes decrease with the increase of the X MO /X MX 2 ratios.

  16. Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics

    Czech Academy of Sciences Publication Activity Database

    Skála, Roman; Ulrych, Jaromír; Ackerman, Lukáš; Jelínek, E.; Dostal, J.; Hegner, E.; Řanda, Zdeněk

    2014-01-01

    Roč. 103, č. 5 (2014), s. 1233-1262. ISSN 1437-3254 R&D Projects: GA AV ČR IAA300130902 Institutional support: RVO:67985831 ; RVO:61389005 Keywords : Bohemian Massif * Cenozoic * continental rift * Roztoky Intrusive Complex * alkaline intrusions * geochemistry Subject RIV: DD - Geochemistry Impact factor: 2.093, year: 2014

  17. Method development and optimization for the determination of rare earth metal ions by capillary zone electrophoresis

    International Nuclear Information System (INIS)

    The separation of rare earth metal ions by capillary zone electrophoresis in the presence of creatinine as UV-absorbing background electrolyte and the complexing agent 2-hydroxyisobutyric acid was investigated. The separation is mainly influenced by the pH of the buffer and the concentration of the complexing agent. Both parameters were used in a central composite design to determine optimal conditions. After modelling of the migration behaviour, the optimal conditions were selected using a multi-criteria approach in which separation coefficient (α), sensitivity and analysis time were considered. Finally, the method was validated regarding its detection limit, linearity and reproducibility

  18. TDPAC studies on metal-complex ferrimagnets

    International Nuclear Information System (INIS)

    TDPAC spectra of 117In (left-arrow 117Cd) and 111Cd (left-arrow 111mCd) in the mixed metal complex N(C4H9)4(M(II)Fe(III)(C2O4)3)(M=Fe,Ni), the related substraces and LiNbO3 have been studied. In this paper, pure potassium iron (III) oxalate was prepared and mixed metal complexes were synthesized by changing amount of reagents and the order added, then observed by TDPAC. 2 mol%Cd was dispersed throughout potassium iron oxalate and potassium nickel oxalate, formulating M(II)0.98Cd(II)0.02C2O4·2H2O (M=Fe, Ni) with the same crystal structure. The formation reaction of mixed metal complex-Fe(II) was faster than that of iron oxalate. Its mixed metal complex-Ni(II) was slower than that of iron oxalate. The rate of quadrupole oscillation was obtained by ωQ(117In)=67.3 Mrad/s and ωQ(111Cd)=29.7 Mrad/s of which values were determined by TDPAC spectra of 117In and 111Cd in LiNbO3 at 4K. The value showed pure ion bond of oxygen coordinated with 117In and 111Cd. 0.08 η was determined by TDPAC spectrum of 111Cd(left-arrow 111mCd). The rate of ωQ of mixed metal oxalate complex was larger than 2.3, indicating 5s and 5p orbital electron took part in bond of oxygen of oxalic acid or approaching oxygen ion to In nucleus depend on the structual relaxation in decaying of 117In(left-arrow 117Cd). (S.Y.)

  19. The structure of metallic complexes of polyacetylene with alkali metals

    Science.gov (United States)

    Baughman, R. H.; Murthy, N. S.; Miller, G. G.

    1983-07-01

    The crystal structures of sodium, potassium, rubidium, and cesium doped polyacetylene have been determined using crystal packing and x-ray diffraction analyses. Each of these metallic complexes is tetragonal, with the polyacetylene chains forming a host lattice in which the alkali metal ions are present in channels. Lithium appears to be too small to stabilize the channel structure and an amorphous structure is observed. Predicted unit cell parameters and x-ray diffraction intensities are in agreement with observed values. Similarities with the alkali metal doped graphite suggest that hybridization between carbon pz orbitals and metal s orbitals occurs. Such hybridization is expected to result in a high conductivity component normal to the chain direction. On the other hand, direct overlap between polymer chains appears small, since alkali metal columns separate polymer chains. Compositions calculated for the channel structures (from meridional diffraction spacings, the intensity of equatorial diffraction lines, measured volume expansion, and distances in model complexes) all range from y=0.12 to 0.18 for (CHMy)x, where M is sodium, potassium, rubidium, or cesium.

  20. The spectroscopic study of complex formation of rhodamine and oxazine dyes with rare-earth elements in solution

    International Nuclear Information System (INIS)

    The results of spectroscopic study of a complex formation of rhodamine and oxazine dyes with rare-earth ions in solutions are presented. Rhodamine dyes in the lactone form and oxazine dyes in the base form are found to form complex compounds of different compositions with metal ion in solution with cations of rare-earth metal. Besides, the spectral-luminescent characteristics of rhodamine and oxazine dyes, specific to their cationic form are restored. Methods of iso molar series and of the saturation curve the composition and stability of the formed complexes are determined. The monovalent metal ions form complexes with the dye molecules of composition 1:1, the divalent ions - 2:1 composition, and the trivalent ions - 3:1. (authors)

  1. Electrons and Spin Waves in Heavy Rare Earth Metals

    DEFF Research Database (Denmark)

    Mackintosh, A. R.

    1972-01-01

    Although the main principles governing the magnetic interactions and magnetic ordering in rare earth metals have been qualitatively understood for some time, it is only relatively recently that a sufficiently detailed study has been made of their electronic and magnetic excitations to place this...... understanding on a more quantitative basis. The experimental evidence on the electronic structure of the rare earths is still rather meager but, so far as it goes, is in accord with the detailed description provided by band structure calculations. On the other hand, the experimental study of the magnon...... dispersion relations by inelastic neutron scattering has provided a wealth of information about the interactions between the local moments, associated with the incompletely filled 4f subshell, and the rest of the crystal. The main emphasis in these notes will be on the interrelation between the electronic...

  2. Transfer of alkaline earth elements in mothers' milk and doses from 45Ca, 90Sr and 226Ra

    International Nuclear Information System (INIS)

    An international programme of work is currently under way to develop methods for calculating doses to infants from ingestion of radionuclides present in mothers' milk. This paper considers the special case of the alkaline earth elements. Models have been developed for 45Ca, 90Sr and 226Ra and the sensitivity of results to various changes in parameter values is discussed. A complication when calculating doses from intakes of radium is that the International Commission on Radiological Protection has previously recommended that doses from decay products of radium should be calculated using element-specific biokinetic models (so-called independent biokinetics). An extension of this method to the models for breastfeeding is proposed. Preliminary estimates of the doses received by the infant for a number of maternal intake scenarios show that doses to the infant can exceed the corresponding adult dose, such as for 45Ca (ratio = 3.1) while, in other cases such as 90Sr, the infant dose can be a significant fraction of the adult dose. (author)

  3. Thermochemical properties of rare earth complexes with salicylic acid

    International Nuclear Information System (INIS)

    Fourteen rare earth complexes with salicylic acid RE(HSal)3.nH2O (HSal = C7H5O3; RE = La-Sm, n = 2; RE = Eu-Lu, n = 1) were synthesized and characterized by elemental analysis, and their thermal decomposition mechanism were studied with TG-DTG technology. The constant-volume combustion energies of complexes, ΔcU, were determined by a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, ΔcHm0, and standard molar enthalpies of formation, ΔfHmo, were calculated

  4. Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

    Directory of Open Access Journals (Sweden)

    Lidi Gao

    2012-01-01

    Full Text Available In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs, thorium (Th, and uranium (U in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni from the polluted sludge was studied with biosurfactant (saponin and sophorolipid elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1 Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2 Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates and F5 (the fraction bound to Fe-Mn oxides. (3 The recovery efficiency of heavy metals (Pb, Ni, and Cr reached about 90–100% using a precipitation method with alkaline solution.

  5. Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

    Science.gov (United States)

    Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

    2012-01-01

    In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution. PMID:22693485

  6. Mass Spectrometric Observation of Doubly Charged Alkaline-Earth Argon Ions.

    Science.gov (United States)

    Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef

    2016-09-01

    Doubly charged diatomic ions MAr(2+) where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr(2+) , 0.4 % for CaAr(2+) , 0.2 % for SrAr(2+) and 0.1 % for BaAr(2+) relative to the corresponding doubly charged atomic ions M(2+) . It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies (D0 ) were calculated and agree well with previously published values. The abundance ratios MAr(+) /M(+) and MAr(2+) /M(2+) generally follow the predicted bond dissociation energies with the exception of MgAr(2+) . Mg(2+) should form the strongest bond with Ar [D0 (MgAr(2+) )=124 to 130 kJ mol(-1) ] but its relative abundance is similar to that of the weakest bound BaAr(2+) (D0 =34 to 42 kJ mol(-1) ). The relative abundances of the various MAr(2+) ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr(2+) ions relative to the composition in the source. The corresponding singly charged MAr(+) ions are also observed but occur at about three orders of magnitude lower intensity than MAr(2+) . PMID:27252087

  7. Copper(II) complexes with cyanoguanidine and o-phenanthroline: Theoretical studies, in vitro antimicrobial activity and alkaline phosphatase inhibitory effect

    Science.gov (United States)

    Martínez Medina, Juan J.; Islas, María S.; López Tévez, Libertad L.; Ferrer, Evelina G.; Okulik, Nora B.; Williams, Patricia A. M.

    2014-01-01

    Calculations based on density functional methods are carried out for two Cu(II) complexes with cyanoguanidine (cnge) and o-phenanthroline (o-phen): [Cu(o-phen)2(cnge)](NO3)2ṡ2H2O (1) and [Cu(o-phen)(cnge)(H2O)(NO3)2] (2). The calculated geometrical parameters are in agreement with the experimental values. The results of Atoms in Molecules (AIM) topological analysis of the electron density indicate that the Cu-N(phen) bonds in complex (1) have lower electron density, suggesting that those bonds are stronger in complex (2). Moreover, the ionic character of the Cu-N bond in the complex (1) is slightly stronger than that in the complex (2) and this situation would explain the fact that only complex (2) was stable in water solution. For this reason, the antimicrobial and enzymatic assays were performed using complex (2). It is well known that the increased use of antibiotics has resulted in the development of resistant bacterial and fungal strains. In this context, the study of novel antimicrobial agents has an enormous importance and metal complexes represent an interesting alternative for the treatment of infectious diseases. The aim of this work is to prove the modification of some biological properties like antimicrobial activity or alkaline phosphatase inhibitory activity upon copper complexation.

  8. Metal Reduction and Mineral Formation by an Alkaliphilic Fe(III)-Reducing Bacterium Isolated from an Alkaline Leachate Pond

    Science.gov (United States)

    Ye, Q.; Roh, Y.; Zhang, C.; Phelps, T. J.; Zhou, J.; Fields, M. M.

    2002-12-01

    Microbial metal reduction plays an important role in biogeochemical cycling of carbon and has the potential for immobilizing metals and radionuclides in diverse environments. The objective of this study was to examine metal reduction and mineral formation using an alkaliphilic bacterium, Alkaliphilus (QYMF), isolated from a leachate-pond containing high levels of salt (Na concentration = 440 - 12,100 ppm) and boron (2,000 - 3,000 ppm) at pH 9.0-10.0. The bacterium was able to use lactate, acetate and hydrogen as alternative electron donors and Fe(III)-citrate, Fe(III)-EDTA, selenate, Cr(VI), Co(III)-EDTA, and iron oxyhydroxide (FeOOH) as electron acceptors. The reduction of Fe(III)-citrate and Fe(III)-EDTA in the presence of H2PO4 and boron resulted in the precipitation of vivianite [Fe3(PO4)2ú8H{2}O]. Formation of sparingly soluble precipitatates, mediated by the alkaliphilic Fe(III)-reducing bacterium, may sequester iron, phosphate, and other metals into more stable and less toxic forms. These results suggest that bioremediation of metal-contaminated alkaline environments may be feasible, and that the process of metal-reduction may occur in alkaline habitats.

  9. Synthesis, characterization and solubility of alkaline earth uranyl carbonates M2[UO2(CO3)3].xH20; M: Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    The release and dispersion of uranium from closed uranium mining sites and the resulting uranium contamination of the natural environment of such sites is a major problem examined in this dissertation. Knowledge of the pollution pathways and processes is indispensable for an assessment of the radiological implications for the human population, to be taken into account in the planning of site rehabilitation work. The formation of secondary uranium minerals may contribute to an immobilization of the uranium, but it is possible as well that such secondary uranium minerals will release uranium. A major task of this dissertation therefore was to examine the conditions of formation of alkaline earth uranyl carbonates in the context of their natural occurrence as observed at some sites, and to answer the question of whether hitherto unknown alkaline earth uranyl carbonates may form in the natural environment, and ought to be taken into account as new source terms. (orig./CB)

  10. Antiretroviral activity of thiosemicarbazone metal complexes.

    Science.gov (United States)

    Pelosi, Giorgio; Bisceglie, Franco; Bignami, Fabio; Ronzi, Paola; Schiavone, Pasqualina; Re, Maria Carla; Casoli, Claudio; Pilotti, Elisabetta

    2010-12-23

    Thiosemicarbazones display a wide antimicrobial activity by targeting bacteria, fungi, and viruses. Here, we report our studies on the antiviral activity of two thiosemicarbazone metal complexes, [bis(citronellalthiosemicarbazonato)nickel(II)] and [aqua(pyridoxalthiosemicarbazonato)copper(II)] chloride monohydrate, against the retroviruses HIV-1 and HTLV-1/-2. Both compounds exhibit antiviral properties against HIV but not against HTLVs . In particular, the copper complex shows the most potent anti-HIV activity by acting at the post-entry steps of the viral cycle. PMID:21121632

  11. Metal-Metal Bonding in Uranium-Group 10 Complexes.

    Science.gov (United States)

    Hlina, Johann A; Pankhurst, James R; Kaltsoyannis, Nikolas; Arnold, Polly L

    2016-03-16

    Heterobimetallic complexes containing short uranium-group 10 metal bonds have been prepared from monometallic IU(IV)(OAr(P)-κ(2)O,P)3 (2) {[Ar(P)O](-) = 2-tert-butyl-4-methyl-6-(diphenylphosphino)phenolate}. The U-M bond in IU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3M(0), M = Ni (3-Ni), Pd (3-Pd), and Pt (3-Pt), has been investigated by experimental and DFT computational methods. Comparisons of 3-Ni with two further U-Ni complexes XU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3Ni(0), X = Me3SiO (4) and F (5), was also possible via iodide substitution. All complexes were characterized by variable-temperature NMR spectroscopy, electrochemistry, and single crystal X-ray diffraction. The U-M bonds are significantly shorter than any other crystallographically characterized d-f-block bimetallic, even though the ligand flexes to allow a variable U-M separation. Excellent agreement is found between the experimental and computed structures for 3-Ni and 3-Pd. Natural population analysis and natural localized molecular orbital (NLMO) compositions indicate that U employs both 5f and 6d orbitals in covalent bonding to a significant extent. Quantum theory of atoms-in-molecules analysis reveals U-M bond critical point properties typical of metallic bonding and a larger delocalization index (bond order) for the less polar U-Ni bond than U-Pd. Electrochemical studies agree with the computational analyses and the X-ray structural data for the U-X adducts 3-Ni, 4, and 5. The data show a trend in uranium-metal bond strength that decreases from 3-Ni down to 3-Pt and suggest that exchanging the iodide for a fluoride strengthens the metal-metal bond. Despite short U-TM (transition metal) distances, four other computational approaches also suggest low U-TM bond orders, reflecting highly transition metal localized valence NLMOs. These are more so for 3-Pd than 3-Ni, consistent with slightly larger U-TM bond orders in the latter. Computational studies of the model systems (PH3)3MU(OH)3I (M = Ni, Pd) reveal

  12. Evaluation of heavy metal complex phytotoxicity

    OpenAIRE

    Vita Vasilyevna Datsenko; Nataliya Lvovna Khimenko

    2016-01-01

    The experimental data dealing with the effect of heavy metals contained in the technogenic contaminated soils on plant objects under controlled conditions was discussed. The aim of this work is to define the quantitative indicators of copper and zinc potential phytotoxicity, namely germination energy, simultaneous germination and duration of the test plants. It was found that the activity of the test plant growth is linked with copper and zinc complex action. Joint effect of copper and zinc i...

  13. Complex Metal Oxide Chemical Gas Sensors

    OpenAIRE

    Šutka, A

    2015-01-01

    The demand for alternative gas sensor materials is increasing following the progress in the electronic industry. Complex ternary oxide materials have been emerging rapidly over 10 last years. Among ternary metal oxide compounds, the spinel ferrites are the most attractive materials due to structural and compositional versatility. This report will highlight the recent developments and will show the potential of the spinel ferrites on gas sensor technology. Sensing mechanisms for a range of gas...

  14. THEORETICAL-ANALYSIS OF THE O(1S) BINDING-ENERGY SHIFTS IN ALKALINE-EARTH OXIDES - CHEMICAL OR ELECTROSTATIC CONTRIBUTIONS

    NARCIS (Netherlands)

    PACCHIONI, G; BAGUS, PS

    1994-01-01

    We report results from ab initio cluster-model calculations on the O(1s) binding energy (BE) in the alkaline-earth oxides, MgO, CaO, SrO, and BaO; all these oxides have a cubic lattice structure. We have obtained values for both the initial- and final-state BE's. A simple point-charge model, where a

  15. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Science.gov (United States)

    2010-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary...

  16. Investigation of properties of rare earth complexes with dibromo--methyl-methylsulfonazo by spectral correction technique

    Indian Academy of Sciences (India)

    Hong-Wen Gao; Fa-Shui Hong; Qing-Song Ye

    2000-12-01

    The reactions were sensitive between seven rare earth (RE) metals Nd(III), La(III), Ce(III), Pr(III), Sm(III), Eu(III) and Gd(III) and dibromo--methylmethylsulfonazo (DBMMSA) in acidic solution. The spectral correction method has been applied in the determination of properties of RE complexes instead of ordinary spectrophotometry. Composition ratios, real molar absorptivities ( ) and stepwise stability constants () of each of the RE complexes were determined easily because the method eliminated the absorption influence of excess of ligand on complex. Results showed that the cumulative values of the complexes were between 3 91 × 1014 and 2 34 × 1028 and the real (not apparent) absorptivity between 8 85 × 104 and 2 12 × 105 l mol-1cm-1 at 640 nm.

  17. Cyclic peptides-assisted trans- port of metal ions across liquid-organic membrane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The formation of alkali and alkaline-earth metal picrate complexes with cyclo(Pro-Gly)n ionophores (1, n = 3; 2, n = 4) can facilitate the migration of metal ions across a bulk liquid CH2Cl2 membrane. The migration behavior was studied by measuring the solution absorption at 356 nm, using a UV/Vis spectrophotometer, and the rates can be determined by comparing the initial absorption of donor solutions with the absorption of the corresponding receiver solutions as the function of time. It was found that cyclic peptide 1 shows higher transport activity for the studied alkali and alkaline-earth metal ions than compound 2, which is related to the backbone flexibility of the cyclic peptides. The findings in this work suggest that the rate of ionophore-facilitated ion transport depends not only on the ability of complex forma-tion in aqueous phase, but also on the ability of complex dissociation in organic phase.

  18. Band structure and electrical properties of MBE grown HfO{sub 2} - based alkaline earth Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Dudek; Grzegorz, Lupina; Grzegorz, Kozlowski; Jarek, Dabrowski; Gunther, Lippert; Hans-Joachim, Muessig; Thomas, Schroeder [IHP-Microelectronics, Frankfurt, Oder (Germany); Dieter, Schmeisser [BTU, Cottbus (Germany)

    2010-07-01

    Ultra thin dielectric films (<20 nm) deposited on TiN electrodes are interesting for MIM capacitor application. High capacitance density and dielectric permittivity must be accompanied by extremely low leakage currents (10{sup -8} A/cm{sup 2}) at bias 0.5 V. To achieve such low leakage currents, high band gap and proper band alignment is required. Occupied electronic states can be probed with standard laboratory photoemission methods. Probing of unoccupied states is more challenging. Synchrotron based PES in combination with XAS forms a powerful method to study the band alignment. ASAM end station located at the U 49/2 PGM 2 beamline of BESSY II (Berlin) offers excellent conditions for performing such measurements. We investigated HfO{sub 2} - based alkaline earth perovskite - BaHfO{sub 3} with subsequent admixture of TiO{sub 2}, resulting in formation of BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} compound. The analysis of data indicates that band gap for HfO{sub 2} is similar to BaHfO{sub 3} and amounts 5.8 eV; for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} it decreases to 3.8 eV. We conclude that the addition of TiO{sub 2} to BaHfO{sub 3} increases significantly the dielectric permittivity but also impacts the band gap alignment. The conduction band offset shrinks, influencing the leakage current behavior.

  19. TDPAC studies on metal-complex ferrimagnets

    Energy Technology Data Exchange (ETDEWEB)

    Ohkubo, Yoshitaka [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Abe, Shizuko; Okada, Takuya [and others

    1997-03-01

    TDPAC spectra of {sup 117}In (left-arrow {sup 117}Cd) and {sup 111}Cd (left-arrow {sup 111m}Cd) in the mixed metal complex N(C{sub 4}H{sub 9}){sub 4}(M(II)Fe(III)(C{sub 2}O{sub 4}){sub 3})(M=Fe,Ni), the related substraces and LiNbO{sub 3} have been studied. In this paper, pure potassium iron (III) oxalate was prepared and mixed metal complexes were synthesized by changing amount of reagents and the order added, then observed by TDPAC. 2 mol%Cd was dispersed throughout potassium iron oxalate and potassium nickel oxalate, formulating M(II){sub 0.98}Cd(II){sub 0.02}C{sub 2}O{sub 4}{center_dot}2H{sub 2}O (M=Fe, Ni) with the same crystal structure. The formation reaction of mixed metal complex-Fe(II) was faster than that of iron oxalate. Its mixed metal complex-Ni(II) was slower than that of iron oxalate. The rate of quadrupole oscillation was obtained by {omega}{sub Q}({sup 117}In)=67.3 Mrad/s and {omega}{sub Q}({sup 111}Cd)=29.7 Mrad/s of which values were determined by TDPAC spectra of {sup 117}In and {sup 111}Cd in LiNbO{sub 3} at 4K. The value showed pure ion bond of oxygen coordinated with {sup 117}In and {sup 111}Cd. 0.08 {eta} was determined by TDPAC spectrum of {sup 111}Cd(left-arrow {sup 111m}Cd). The rate of {omega}{sub Q} of mixed metal oxalate complex was larger than 2.3, indicating 5s and 5p orbital electron took part in bond of oxygen of oxalic acid or approaching oxygen ion to In nucleus depend on the structual relaxation in decaying of {sup 117}In(left-arrow {sup 117}Cd). (S.Y.)

  20. Photoelectron Experiments and Studies of X-Ray Absorption Near Edge Structure in Alkaline-Earth and Rare - Fluorides.

    Science.gov (United States)

    Gao, Yuan

    Alkaline-earth fluorides and rare-earth trifluorides possess technological importance for applications in multi -layer electronic device structures and opto-electronic devices. Interfaces between thin films of YbF _3 and Si(111) substrates were studied by photoelectron spectroscopy and x-ray absorption spectroscopy using synchrotron radiation. Results of YbF_3 /Si(111) were compared with those of TmF _3/Si(111). While electrons in the Si valence band are prevented from occupying the empty 4f levels in TmF_3 at the interface by the on -site Coulomb repulsion energy, the charge transfer from Si to YbF_3 is possible because the totally filled 4f states in Yb still lie below the Si valence band maximum. The theory of x-ray absorption near edge structure (XANES) is incomplete except for a few particularly simple special cases. A Bragg reflection model was developed to qualitatively explain the oscillations in XANES, in terms of the scattering of the photoelectron wave between families of lattice planes as set out by the Bragg condition for backscattering. The model was found to represent the data for systems with nearly free electron like conduction bands reasonably well. High resolution CaF_2 fluorine K edge XANES was used as a prototype to understand XANES in more depth on systems with strong core hole effects. Unlike previous work which involved multiple scattering cluster calculations that include only short range order effects, both the long range order and the symmetry breaking core holes are included in a new bandstructure approach in which the core hole is treated with a supercell technique. A first principles calculation with the use of pseudopotentials successfully reproduced all the main features of the first 15 eV of the fluorine K edge in CaF_2 which had not been explained with the cluster calculations. A comparison of the theoretical and experimental fluorine K edges in CaF_2 and BaF _2 was used to identify the structure related features. The possibility

  1. Metal complexes of tetrazole-containing azomethins

    International Nuclear Information System (INIS)

    Complexes of M(L-H)2, M(L-H)2·nMX2 (n=1, 2) type were prepared in result of interaction of methanol solutions of acetates and chlorides of corresponding metals (M=Cu, Zn, Cd) and L (L-tetrazole-containing azomethins) at molar ratio of reagents, equal to 1:2. Composition of synthesized azomethins and their complexes was investigated by the methods of IR, UV spectroscopy and magnetic measurements. The most general way of coordination lies in formation of M-L σ-bond due to the presence of N-H aminogroup in ligand system. Formation of complexes of complicated composition is caused by nonplanar structure of azomethins

  2. The miocene Ashizuri complex (SW Japan): source and magma differentiation of an alkaline plutonic assemblage in an island-arc environment

    International Nuclear Information System (INIS)

    The Ashizuri complex, mainly composed of gabbro, syenite and granite, belongs to the Shimanto Middle Miocene magmatic province and represents one of the rare examples of a within-plate-like alkaline complex in an island-arc setting. This complex is temporally and spatially associated with calc-alkaline volcano-plutonic bodies and, in a lesser amount, with T- to E-MORB and arc tholeites. The least evolved rocks of the Ashizuri complex are enriched in light rare earth elements ((La/Yb)n = 8-16) and other incompatible elements (e.g., Ba/La ≅ 11-13; Ba/Nb ≅ 9-11), features of intra-plate alkali basalts. These features are also characteristic of the more evolved rocks of acidic composition. Trace element petrogenetic modelling suggests that all the different components of the suite are co-magmatic and points out the major role of crystal fractionation process in its genesis. Sr and Nd isotopic data (εNdi = -0.59 to +2.56; εSri = -9.19 to + 2.90) suggest that assimilation as well as crystal fractionation occurred. Derivation through mixing of a MORB-like source and an old enriched component (e.g., sediment or old crust), or through partial melting of lower crust cannot explain both the elemental and isotopic signature of the Ashizuri suite. An OIB-type enriched mantle source is required. By comparison with volcanic rocks in southwest Japan and in the neighbouring Philippine Sea oceanic plate, this source is believed to lie not in the sub-Japan lithosphere but deeper in the asthenosphere prevalent under Japan and the Philippine Sea Plate. (authors). 83 refs., 8 figs., 7 tabs

  3. 40 CFR 721.4596 - Diazo substituted carbomonocyclic metal complex.

    Science.gov (United States)

    2010-07-01

    ... metal complex. 721.4596 Section 721.4596 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4596 Diazo substituted carbomonocyclic metal complex. (a) Chemical... as a diazo substituted carbomonocyclic metal complex (PMN P-94-1039) is subject to reporting...

  4. Organic light emitting diodes the use of rare earth and transition metals

    CERN Document Server

    Pereira, Luiz F R

    2012-01-01

    The Organic Light Emitting Diode (OLED) world is one of the most fascinated fields of research with an enormous technological application market. Besides the actual use in displays, the intrinsic and unique properties of that electroluminescent devices opens new potential applications since efficient lighting to decorative environments, with a very simple incorporation in architectural design. This book addresses the development of OLEDs based on rare-earth and transition-metal complexes, focusing in special the Europium, Terbium, Ruthenium and Rhenium. The idea is to explain how these organic

  5. Methyl Complexes of the Transition Metals.

    Science.gov (United States)

    Campos, Jesús; López-Serrano, Joaquín; Peloso, Riccardo; Carmona, Ernesto

    2016-05-01

    Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, that is, based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition-metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition-metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last five years. After a panoramic overview on M-CH3 compounds of Groups 3 to 11, which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity. PMID:26991740

  6. Molecular early main group metal hydrides: synthetic challenge, structures and applications.

    Science.gov (United States)

    Harder, Sjoerd

    2012-11-25

    Within the general area of early main group metal chemistry, the controlled synthesis of well-defined metal hydride complexes is a rapidly developing research field. As group 1 and 2 metal complexes are generally highly dynamic and lattice energies for their [MH](∞) and [MH(2)](∞) salts are high, the synthesis of well-defined soluble hydride complexes is an obvious challenge. Access to molecular early main group metal hydrides, however, is rewarding: these hydrocarbon-soluble metal hydrides are highly reactive, have found use in early main group metal catalysis and are potentially also valuable molecular model systems for polar metal hydrides as a hydrogen storage material. The article focusses specifically on alkali and alkaline-earth metal hydride complexes and discusses the synthetic challenge, molecular structures, reactivity and applications. PMID:23012695

  7. Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics

    Science.gov (United States)

    Skála, Roman; Ulrych, Jaromír; Ackerman, Lukáš; Jelínek, Emil; Dostál, Jaroslav; Hegner, Ernst; Řanda, Zdeněk

    2014-07-01

    The České středohoří Mts. is the dominant volcanic center of the Ohře (Eger) rift zone. It hosts the Roztoky Intrusive Complex (RIC), which is made up of a caldera vent and intrusions of 33-28-Ma-old hypabyssal bodies of essexite-monzodiorite-sodalite syenite series accompanied by a radially oriented 30-25-Ma-old dike swarm comprising about 1,000 dikes. The hypabyssal rocks are mildly alkaline mostly foid-bearing types of mafic to intermediate compositions. The dike swarm consists of chemically mildly alkaline and rare strongly alkaline rocks (tinguaites). The geochemical signatures of the mildly alkaline hypabyssal and associated dike rocks of the RIC are consistent with HIMU mantle sources and contributions from lithospheric mantle. The compositional variations of essexite and monzodiorite can be best explained by fractional crystallization of parent magma without significant contributions of crustal material. On the other hand, the composition of monzosyenite, leuco-monzodiorite and sodalite syenite reflects fractional crystallization coupled with variable degrees of crustal assimilation. It is suggested that the parent magmas in the Ohře rift were produced by an adiabatic decompression melting of ambient upper mantle in response to lithospheric extension associated with the Alpine Orogeny.

  8. The Magnetic Ordering of Heavy Rare Earth Metals

    Science.gov (United States)

    Nordström, Lars

    1998-03-01

    The electronic and magnetic structures of the rare earth metals with hcp structure (Gd--Tm) are calculated by a full-potential LAPW method, which allows for non-collinear magnetism within the local approximation to spin-density functional theory. The 4f electrons are taken as localized, but their spin moment constrained as to fulfil Russel-Saunders coupling, polarizes the itinerant valence electrons. It is found that there are two competing magnetic structures; the ferromagnetic state, which dominates for the left-most elements (Gd and Tb), and a planar helical wave, which is found to have lowest energy for the last elements Er and Tm. In Ho the competition between the two leads to a compromise --- a helical cone. This trend is in accordance with the experimental situation. The mechanism behind the stabilization of the helical wave is confirmed to be an opening of a partial gap at the so-called ``webbing'' of the Fermi surface. This feature is found to exhibit nesting, a fact which is known both from earlier non-spin-polarized calculations and de Haas-van Alphen measurements. In contrast to prevailing models and earlier more primitive calculations, this nesting is found to exist for all elements, i.e. even for gadolinium. Instead, the magnitude of the spin splitting of the valence electrons due to the magnetic 4f states, is found to be an important quantity which has been missed out in the standard models for the magnetic structure of the rare earths.

  9. NMR study of rare earth and actinide complexes

    International Nuclear Information System (INIS)

    Proton magnetic resonance studies of lanthanide shift reagents with olefin-transition metal complexes, monoamines and diamines as substrates are described. Shift reagents for olefins are reported: Lnsup(III)(fod)3 can induce substantial shifts in the nmr spectra of a variety of olefins when silver 1-heptafluororobutyrate is used to complex the olefin. The preparation, properties and efficiency of such systems are described. Configurational aspects and exchange processes of Lnsup(III)(fod)3 complexes with secondary and tertiary monoamines are analysed by means of dynamic nmr. Factors influencing the stability and the stoichiometry of these complexes and various processes such as nitrogen inversion and ligand exchange are discussed. At low temperature, ring inversion can be slow on an nmr time-scale for Lnsup(III)(fod)3-diamino chelates. Barriers to ring inversion in substituted ethylenediamines and propanediamines are obtained. Steric factors appear to play an important role in the stability and kinetics of these bidentate species. The synthesis of uranium-IV crown-ether and cryptate complexes is described. A conformational study of these compounds show evidence of an insertion of the paramagnetic cation as witnessed by the large induced shifts observed. The insertion of uranium in the macrocyclic ligand of a UCl4-dicyclohexyl-18-crown-6 complex is confirmed by an X-ray structural determination

  10. Structural studies of human alkaline phosphatase in complex with strontium: Implication for its secondary effect in bones

    Science.gov (United States)

    Llinas, Paola; Masella, Michel; Stigbrand, Torgny; Ménez, André; Stura, Enrico A.; Le Du, Marie Hélène

    2006-01-01

    Strontium is used in the treatment of osteoporosis as a ranelate compound, and in the treatment of painful scattered bone metastases as isotope. At very high doses and in certain conditions, it can lead to osteomalacia characterized by impairment of bone mineralization. The osteomalacia symptoms resemble those of hypophosphatasia, a rare inherited disorder associated with mutations in the gene encoding for tissue-nonspecific alkaline phosphatase (TNAP). Human alkaline phosphatases have four metal binding sites—two for zinc, one for magnesium, and one for calcium ion—that can be substituted by strontium. Here we present the crystal structure of strontium-substituted human placental alkaline phosphatase (PLAP), a related isozyme of TNAP, in which such replacement can have important physiological implications. The structure shows that strontium substitutes the calcium ion with concomitant modification of the metal coordination. The use of the flexible and polarizable force-field TCPEp (topological and classical polarization effects for proteins) predicts that calcium or strontium has similar interaction energies at the calcium-binding site of PLAP. Since calcium helps stabilize a large area that includes loops 210–228 and 250–297, its substitution by strontium could affect the stability of this region. Energy calculations suggest that only at high doses of strontium, comparable to those found for calcium, can strontium substitute for calcium. Since osteomalacia is observed after ingestion of high doses of strontium, alkaline phosphatase is likely to be one of the targets of strontium, and thus this enzyme might be involved in this disease. PMID:16815919

  11. Study on silicon oxide coated on silver nanocrystal to enhance fluorescence intensity of rare earth complexes

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Yan-rong; Lin, Xue-mei; Wang, Ai-ling; Wang, Zhong-xia; Kang, Jie; Chu, Hai-bin, E-mail: binghai99@gmail.com; Zhao, Yong-liang, E-mail: hxzhaoyl@163.com

    2014-10-15

    Twelve kinds of rare earth complexes were synthesized using halo-benzoic acid as anion ligand and Sm{sup 3+} and Dy{sup 3+} as central ions, respectively. The complexes were characterized by elemental analysis, rare earth coordination titration and electrospray ionization mass spectra, from which the compositions of the complexes were confirmed to be RE(p-FBA){sub 3}·H{sub 2}O, RE(p-ClBA){sub 3}·2H{sub 2}O, RE(p-BrBA){sub 3}·H{sub 2}O, RE(o-FBA){sub 3}·2H{sub 2}O, RE(o-ClBA){sub 3}·H{sub 2}O, RE(o-BrBA){sub 3}·H{sub 2}O (RE=Sm{sup 3+}, Dy{sup 3+}). Besides, IR spectra and UV–visible absorption spectroscopy indicated that the carboxyl oxygen atoms of ligands coordinated to the rare earth ions. Moreover, Ag@SiO{sub 2} core–shell nanoparticles (NPs) were prepared via a modified Stöber method. The average diameters of silver cores were typically between 60 nm and 70 nm, and the thicknesses of the SiO{sub 2} shells were around 10 nm, 15 nm and 25 nm, respectively. The influence of Ag@SiO{sub 2} NPs on the luminescence properties of the rare earth complexes showed that the luminescence intensities of rare earth complexes were enhanced remarkably. As the thickness of SiO{sub 2} shell increases in the range of 10–25 nm, the effect of metal-enhanced fluorescence become obvious. The mechanism of the changes of the fluorescence intensity is also discussed. - Highlights: • Among 10–25 nm, the thicker the shell thickness, the better the fluorescence effect. • The strong the intensity of the pure complexes, the smaller the multiple enhanced. • The intensity of Sm(p-BrBA){sub 3}·H{sub 2}O is the strongest among Sm(p-XBA){sub 3}·nH{sub 2}O complexes. • The intensity of Dy(p-ClBA){sub 3}·2H{sub 2}O is the strongest among Dy(p-XBA){sub 3}·nH{sub 2}O complexes. • When halogen is in o-position, the intensity of RE(o-ClBA){sub 3}·H{sub 2}O is the strongest.

  12. Electrochemical behaviour of metal hexacyanoferrate converted to metal hydroxide films immobilized on indium tin oxide electrodes-Catalytic ability towards alcohol oxidation in alkaline medium

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: In this work, we demonstrate a simple method to modify indium tin oxide (ITO) electrodes in order to perform electro-catalytic oxidation of alcohols in alkaline medium. Metal hexacyanoferrate (MHCF) films such as nickel hexacyanoferrate (NiHCF) and copper hexacyanoferrate (CuHCF) were successfully immobilized on ITO electrodes using an electrochemical method. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the structural and morphological aspects of MHCF films. Cyclic voltammetry (CV) was used to study the redox properties and to determine the surface coverage of these films on ITO electrodes. Electrochemical potential cycling was carried out in alkaline medium in order to alter the chemical structure of these films and convert to their corresponding metal hydroxide films. SEM and XPS were performed to analyze the structure and morphology of metal hydroxide modified electrodes. Electro-catalytic oxidation ability of these films towards methanol and ethanol in alkaline medium was investigated using CV. From these studies we found that metal hydroxide modified electrodes show a better catalytic performance and good stability for methanol oxidation along with the alleviation of CO poisoning effect. We have obtained an anodic oxidation current density of ∼82 mA cm-2 for methanol oxidation, which is at least 10 fold higher than that of any metal hydroxide modified electrodes reported till date. The onset potential for methanol oxidation is lowered by ∼200 mV compared to other chemically modified electrodes reported. A plausible mechanism was proposed for the alcohol oxidation based on the redox properties of these modified electrodes. The methodology adapted in this work does not contain costlier noble metals like platinum and ruthenium and is economically viable.

  13. Metal ammine complexes for hydrogen storage

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Sørensen, Rasmus Zink; Johannessen, Tue;

    2005-01-01

    The hopes of using hydrogen as an energy carrier are severely dampened by the fact that there is still no safe, high-density method available for storing hydrogen. We investigate the possibility of using metal ammine complexes as a solid form of hydrogen storage. Using Mg(NH3)(6)Cl-2 as the example......, we show that it can store 9.1% hydrogen by weight in the form of ammonia. The storage is completely reversible, and by combining it with an ammonia decomposition catalyst, hydrogen can be delivered at temperatures below 620 K....

  14. Evaluation of heavy metal complex phytotoxicity

    Directory of Open Access Journals (Sweden)

    Vita Vasilyevna Datsenko

    2016-07-01

    Full Text Available The experimental data dealing with the effect of heavy metals contained in the technogenic contaminated soils on plant objects under controlled conditions was discussed. The aim of this work is to define the quantitative indicators of copper and zinc potential phytotoxicity, namely germination energy, simultaneous germination and duration of the test plants. It was found that the activity of the test plant growth is linked with copper and zinc complex action. Joint effect of copper and zinc is manifested both in inhibition of lettuce growth and determined, above all, by the nature contamination, soil properties and biological specificity of the test plants.

  15. Mixed-metal hydroxycarboxylic acid complexes

    International Nuclear Information System (INIS)

    Formation constants for mixed-metal complexes, Kmmc, between uranium(VI), as the central metal ion, and each one of the metal ions, iron(III), aluminium(III), indium(III) and copper(II) have been determined using data from potentiometric measurements. In each case one of the hydroxycarboxylic acids, citric, tartaric or malic, was used as a ligand. At 298.15 K the values of -log Kmmc for the investigated systems are uranyl iron(II) citrate, 2.45; uranyl iron(III) malate, 7.37; uranyl aluminium(III) citrate, 8.21; uranyl aluminium(III) tartarate, >12; uranyl aluminium(III) malate, 8.06; uranyl indium(III) citrate, 11.3; uranyl indium(III) tartarate, 7.88; uranyl indium(III) malate, 7.45; uranyl copper(II) citrate -1.41; uranyl copper(II) tartarate, -1.17; and uranyl copper(II) malate, -1.11. (author)

  16. A Kinetically Mechanistic Investigation of Oxidation of 1,4-Butanediamine by Ag(Ⅲ)Complex in Alkaline Medium

    Institute of Scientific and Technical Information of China (English)

    SONG,Changying; SHAN,Jinhuan; Shen,Shigang; Sun,Hanwen

    2009-01-01

    Kinetics and mechanism of oxidation of 1,4-butanediamine by a Ag (Ⅲ)complex were studied spectropho-tometrically in alkaline medium at constant ion strength. The reaction shows first order with respect to the Ag(Ⅲ)complex and 1,4.butanediamine respectively. The second order rate constant,k`:increased with the increasing in[OH-],and decreased with the increasing in[IO4-4].A plausible mechanism was proposed from the kinetics study.The rate equations derived from the mechanism Can explain all experimental phenomena. The activation parameters were calculated.

  17. Interaction of Pu(IV,VI) hydroxides/oxides with metal hydroxides/oxides in alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Fedoseev, A.M.; Krot, N.N.; Budantseva, N.A.; Bessonov, A.A.; Nikonov, M.V.; Grigoriev, M.S.; Garnov, A.Y.; Perminov, V.P.; Astafurova, L.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

    1998-08-01

    The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.

  18. Selective modulation of the CD4 molecular complex by Pseudomonas aeruginosa alkaline protease and elastase

    DEFF Research Database (Denmark)

    Pedersen, B K; Kharazmi, A; Theander, T G;

    1987-01-01

    The binding of monoclonal antibodies against CD4 was specifically inhibited by treatment of human CD4+ cells with either alkaline protease (AP) or elastase (Ela), purified from Pseudomonas aeruginosa. Binding of antibodies against CD3 (pan T), CD5 (pan T), CD8 (T suppressor/cytotoxic), HLA-ABC, HLA......-DR, HLA-DQ, HLA-DP/DR, and beta 2 microglobulin was not inhibited by AP or Ela. Heat-inactivation of the proteases at 65 degrees C for 20 min or treatment with the metal chelator EDTA abolished the inhibitory activity of both proteases. These findings may serve to develop novel immunological methods for...

  19. Complex rare-earth aluminum hydrides: mechanochemical preparation, crystal structure and potential for hydrogen storage.

    Science.gov (United States)

    Weidenthaler, Claudia; Pommerin, André; Felderhoff, Michael; Sun, Wenhao; Wolverton, Christopher; Bogdanović, Borislav; Schüth, Ferdi

    2009-11-25

    A novel type of complex rare-earth aluminum hydride was prepared by mechanochemical preparation. The crystal structure of the REAlH(6) (with RE = La, Ce, Pr, Nd) compounds was calculated by DFT methods and confirmed by preliminary structure refinements. The trigonal crystal structure consists of isolated [AlH(6)](3-) octahedra bridged via [12] coordinated RE cations. The investigation of the rare-earth aluminum hydrides during thermolysis shows a decrease of thermal stability with increasing atomic number of the RE element. Rare-earth hydrides (REH(x)) are formed as primary dehydrogenation products; the final products are RE-aluminum alloys. The calculated decomposition enthalpies of the rare-earth aluminum hydrides are at the lower end for reversible hydrogenation under moderate conditions. Even though these materials may require somewhat higher pressures and/or lower temperatures for rehydrogenation, they are interesting examples of low-temperature metal hydrides for which reversibility might be reached. PMID:19886669

  20. Cytochrome c forms complexes and is partly reduced at interaction with GPI-anchored alkaline phosphatase

    Czech Academy of Sciences Publication Activity Database

    Dadák, V.; Janiczek, O.; Vrána, Oldřich

    2002-01-01

    Roč. 1570, č. 1 (2002), s. 9-18. ISSN 0304-4165 Institutional research plan: CEZ:AV0Z5004920 Keywords : cytochrome c * aromatic amino acid * alkaline phosphatase Subject RIV: BO - Biophysics Impact factor: 1.845, year: 2002

  1. Geochemistry of Alkaline—Ultrabasic Rocks in the Jijie Complex,Lufeng,Yunnan

    Institute of Scientific and Technical Information of China (English)

    黄智龙; 颜以彬; 等

    1996-01-01

    is paper is concerned with the geochemical features of major elements,transition metal elements,large ion lithophile elements,rare-earth elements and Sr isotopes in alkaline-ul-trabasic rocks in the Jijie complex of Lufeng,Yunnan Province,which is located in southern Sichuan-Yunnan rift zone,one of Luoci alkaline-ultrabasic complexes in central Ynnnan,Moreover,its origin pertaining primary magma,magma soure region,fractional crystallization,etc.are also discussed in the present paper.

  2. Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada.

    Science.gov (United States)

    Chen, Wei; Kamenetsky, Vadim S; Simonetti, Antonio

    2013-01-01

    The Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na2Ca(CO3)2] and gregoryite [(Na2,K2,Ca)CO3]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic carbonates. Consequently, this leads to the conundrum as to the composition of primary, mantle-derived carbonatite liquids. Here we report a detailed chemical investigation of melt inclusions associated with intrusive (plutonic) calcite-rich carbonatites from the ~120 Ma carbonatite complex of Oka (Canada). Melt inclusions are hosted by magnetite (Fe3O4), which crystallizes through a significant period of carbonatite melt solidification. Our results indicate mineral assemblages within the melt inclusions that are consistent with those documented in natrocarbonatite lavas. We propose therefore that derivation of alkali-enriched parental carbonatite melts has been more prevalent than that preserved in the geological record. PMID:24173270

  3. Influence of alkali and alkaline earth ions on the -alkylation of the lower rim phenolic-OH groups of -tert-butyl-calix[4]arene to result in amide-pendants: Template action of K+ and the structure of K+ bound tetra-amide derivative crystallized with a -tert-butylcalix[4]arene anion

    Indian Academy of Sciences (India)

    Amjad Ali; Chebrolu P Rao; Philippe Guionneau

    2008-03-01

    Role of alkali and alkaline earth ions on the formation of calix[4]arene-amide derivatives through -alkylation of the lower rim phenolic-OH groups in general and template action of K+ in particular have been explored. Na+ and K+ ions among alkali, and Ca2+ and Sr2+ ions among alkaline earth have shown tetra-amide derivatives bound to metal ion species. Among all these, potassium salts act as template and yields a K+ bound tetra-amide derivative where the charge is counter balanced by a calix[4] arene-monoanion and the product is crystallographically characterized. Change in the amide precursor used in these -alkylation reactions has no effect on the type of the amide derivative formed. Also demonstrated is a direct one-step reaction for the preparation of 1,3-di-amide derivative in high yield and low reaction period using CsHCO3.

  4. Effects of complexing compounds on sorption of metal ions to cement

    Energy Technology Data Exchange (ETDEWEB)

    Loevgren, Lars [Umeaa Univ. (Sweden). Inorganic chemistry

    2005-12-15

    This present report is a literature review addressing the effects of complexing ligands on the sorption of radionuclides to solid materials of importance for repositories of radioactive waste. Focus is put on laboratory studies of metal ion adsorption to cement in presence of chelating agents under strongly alkaline conditions. As background information, metal sorption to different mineral and cement phases in ligand free systems is described. Furthermore, surface complexation model (SCM) theories are introduced. According to surface complexation theories these interactions occur at specific binding sites at the particle/water interface. Adsorption of cationic metals is stronger at high pH, and the adsorption of anions occurs preferentially at low pH. The adsorption of ions to mineral surfaces is a result of both chemical bonding and electrostatic attraction between the ions and charged mineral surfaces. By combining uptake data with spectroscopic information the sorption can be explained on a molecular level by structurally sound surface complexation models. Most of the metal sorption studies reviewed are dealing with minerals exhibiting oxygen atoms at their surfaces, mainly oxides of Fe(II,III) and Al(III), and aluminosilicates. Investigations of radionuclides are focused on clay minerals, above all montmorillonite and illite. Which mechanism that is governing the metal ion adsorption to a given mineral is to a large extent depending on the metal adsorbed. For instance, sorption of Ni to montmorillonite can occur by formation of inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and by formation of a Ni phyllosilicate phase parallel to montmorillonite layers. Also metal uptake to cement materials can occur by different mechanisms. Cationic metals can both be attached to cement (calcium silicate hydrate, CSH) and hardened cement paste (HCP) by formation of inner-sphere complexes at specific surface sites and by

  5. Effects of complexing compounds on sorption of metal ions to cement

    International Nuclear Information System (INIS)

    This present report is a literature review addressing the effects of complexing ligands on the sorption of radionuclides to solid materials of importance for repositories of radioactive waste. Focus is put on laboratory studies of metal ion adsorption to cement in presence of chelating agents under strongly alkaline conditions. As background information, metal sorption to different mineral and cement phases in ligand free systems is described. Furthermore, surface complexation model (SCM) theories are introduced. According to surface complexation theories these interactions occur at specific binding sites at the particle/water interface. Adsorption of cationic metals is stronger at high pH, and the adsorption of anions occurs preferentially at low pH. The adsorption of ions to mineral surfaces is a result of both chemical bonding and electrostatic attraction between the ions and charged mineral surfaces. By combining uptake data with spectroscopic information the sorption can be explained on a molecular level by structurally sound surface complexation models. Most of the metal sorption studies reviewed are dealing with minerals exhibiting oxygen atoms at their surfaces, mainly oxides of Fe(II,III) and Al(III), and aluminosilicates. Investigations of radionuclides are focused on clay minerals, above all montmorillonite and illite. Which mechanism that is governing the metal ion adsorption to a given mineral is to a large extent depending on the metal adsorbed. For instance, sorption of Ni to montmorillonite can occur by formation of inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and by formation of a Ni phyllosilicate phase parallel to montmorillonite layers. Also metal uptake to cement materials can occur by different mechanisms. Cationic metals can both be attached to cement (calcium silicate hydrate, CSH) and hardened cement paste (HCP) by formation of inner-sphere complexes at specific surface sites and by

  6. 40 CFR 721.4594 - Substituted azo metal complex dye.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted azo metal complex dye. 721... Substances § 721.4594 Substituted azo metal complex dye. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted azo metal...

  7. Host–guest complexes of mixed glycol-bipyridine cryptands: prediction of ion selectivity by quantum chemical calculations, part V

    OpenAIRE

    Svetlana Begel; Ralph Puchta; Rudi van Eldik

    2013-01-01

    The selectivity of the cryptands [2.2.bpy] and [2.bpy.bpy] for the endohedral complexation of alkali, alkaline-earth and earth metal ions was predicted on the basis of the DFT (B3LYP/LANL2DZp) calculated structures and complex-formation energies. The cavity size in both cryptands lay between that for [2.2.2] and [bpy.bpy.bpy], such that the complexation of K+, Sr2+ and Tl3+ is most favorable. While the [2.2.bpy] is moderately larger, preferring Rb+ complexation and demonstrating equal priorit...

  8. Equilibrium studies on mixed ligand complexes of some tripositive rare earth ions

    International Nuclear Information System (INIS)

    Interaction of the rare earth ions, La3+, Ce3+, Pr3+, Nd3+, Sm3+ and Eu3+ with the pair of ligands 1-amino-2-naphthol-4-sulphonic acid (an, H2A) and o-aminophenol (ap, HB) have been studied in aqueous solution at 25 degC (μ=0.1 M KNO3/NaCl). Equilibrium constants of the reactions involving the formations of the mixed ligand species MAB, MA2B2-, MB2A- (M = metal ion) and the binary complexes containing up to three ligand molecules have been evaluated from the pH-metric data, and coordinating behaviour of the ligands in the formation of the mixed ligand complexes has been discussed. (author). 10 refs., 1 tab., 1 fig

  9. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Han, M.K.

    2006-05-06

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline

  10. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Mi-Kyung Han

    2006-05-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline

  11. Nitrogen vacancy complexes in nitrogen irradiated metals

    International Nuclear Information System (INIS)

    Gas desorption and positron annihilation techniques have been employed to study the evolution of nitrogen associated defects in nitrogen irradiated metals: Fe, Ni, Mo and W. Nitrogen in these metals has a rather high affinity to vacancy type defects. The results obtained for low irradiation dose show that substitutional nitrogen (NV; with V = vacancy) is formed. The nitrogen vacancy complex dissociates at temperatures ranging from 350 K for Ni to 900 K for Mo and 1,100 K for W. At high doses defects are formed which can be characterized as nitrogen saturated vacancy clusters. These defect, as observed by helium probing, disappear during annealing for nickel at 800 K, and for Mo at 1,100 K. The direct observation of the desorbing nitrogen for nickel and molybdenum reveals a very fast desorption transient at the dissociation temperature of the clusters. This is the characteristic desorption transient of a small nitride cluster, e.g., by shrinkage with constant rate. For iron the nitrogen desorption is more complicated because of a general background that continuously rises with temperature. With the positron beam technique depth information was obtained for defects in iron and the defect character could be established with the help of the information provided on annihilation with conduction and core electrons of the defect trapped positrons

  12. Electron-phonon coupling in the rare-earth metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

    We have estimated the strength of the mass enhancement of the conduction electrons due to electron-phonon interaction in the rare metals Sc, Y, and La–Lu. The underlying self-consistent energy bands were obtained by means of the scalar relativistic linear-muffin-tin-orbital method, and the electron......-phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4......f states. The calculated electron-phonon mass enhancement λ exhibits a pronounced variation through the series with a maximum value of 1.07 in Pr and a minimum of 0.3 in Ho. We analyze the experimental data from specific heat and de Haas–van Alphen measurements in light of the calculated electron...

  13. Kinetics of dissolution of uranium metal foil by alkaline hydrogen peroxide

    International Nuclear Information System (INIS)

    To develop a new process for the production of 99Mo using low-enriched uranium targets, uranium dissolution in alkaline hydrogen peroxide was studied. Molybdenum-99 is a parent of the widely used medical isotope 99mTc. The rates of uranium dissolution in alkaline hydrogen peroxide solution were measured in an open, batch-type reactor and were found to be a 0.25th order reaction with respect to equilibrium hydrogen peroxide concentration. In general, uranium dissolution can be classified as a low-base (0.2 M hydroxide) process. In the low-base process, both the equilibrium hydrogen peroxide and the hydroxide concentrations affect the rate of uranium dissolution. In the high-base process, uranium dissolution is independent of alkali concentration; the presence of base affects only the equilibrium concentration of hydrogen peroxide. An empirical kinetics model is proposed and discussed

  14. Thermodynamic, kinetic and mechanistic investigations of Piperazine oxidation by Diperiodatocuprate(III) complex in aqueous alkaline medium

    Indian Academy of Sciences (India)

    Vijay P Pattar; Prashant A Magdum; Deepa G Patil; Sharanappa T Nandibewoor

    2016-03-01

    The kinetics of oxidation of piperazine by the copper complex, diperiodatocuprate(III) in alkaline medium was studied at 298 K, at an ionic strength of 2.0*10-2 mol dm-3. The reaction between piperazine and diperiodatocuprate(III) in aqueous alkaline medium exhibited 1:2 stoichiometry. The oxidation products were identified by UV-Visible, GC-MS and IR spectral studies. In the present study we have obtained different kinetic observations. The reaction exhibited unit order in case of diperiodatocuprate(III), while less than unit order with respect to piperazine. The addition of alkali and periodate retarded the rate of reaction. The effects of added products, ionic strength and dielectric constant on the rate of the reaction were also studied. The active species of diperiodatocuprate(III) in alkaline media is [Cu(OH)2(H3IO6)]-. The activation parameters with respect to the rate determining step and the thermodynamic quantities with respect to the equilibrium steps were evaluated and discussed. The plausible mechanism consistent with the experimental results was proposed and discussed in detail.

  15. Hyperpolarizabilities of alkaline-earth metal ions Be+, Mg+, and Ca+

    Science.gov (United States)

    Yin, Dong; Zhang, Yong-Hui; Li, Cheng-Bin; Gao, Ke-Lin; Shi, Ting-Yun

    2016-09-01

    The knowledge of the hyperpolarizabilities of atoms and ions is helpful for the analysis of the high order effects of the frequency shifts in precision spectroscopy experiments. Liu et al. [Phys. Rev. Lett. 114, 223001 (2015)] proposed to establish all-optical trapped ion clocks using laser at the magic wavelength for clock transition. To evaluate the high-order frequency shifts in this new scheme of optical clocks, hyperpolarizabilities are needed, but absent. Using the finite field method based on the B-spline basis set and model potentials, we calculated the electric-field-dependent energy shifts of the ground and low-lying excited states in Be+, Mg+, and Ca+ in the field strength range of 0.0-6×10-5 a.u.. The scalar and tensor polarizabilities ( α 0, α 2) and hyperpolarizabilities ( γ 0, γ 2, γ 4) were deduced. The results of the hyperpolarizabilities for Be+ showed good agreement with the values in literature, implying that the present method can be applied for the effective estimation of the atomic hyperpolarizabilities, which are rarely reported but needed in experiments. The feasibility of optical trapping of Ca+ is discussed, and the contributions of hyperpolarizabilities to the transition frequency shift for Ca+ in the optical dipole trap are estimated using quasi-electrostatic approximation.

  16. IR spectra and structure of di-2-ethylhexyl phosphates of alkali and alkaline earth metals

    International Nuclear Information System (INIS)

    Using the method of IR spectroscopy (25-4000 cm-1) types of di-2-ethylhexylphosphate-anion (X-) coordination to M+ (M = Li, Na, K, Rb, Cs) and Mg2+ have been studied in solid salts and their solutions in CCl4. Analysis of IR spectra has shown that CsX in the CCl4 medium and in the solid phase exists practically only as one compound and it contains two nonequivalent bonds: M-O and M...O, i. e. the POO - group in CsX is bidentate. Besides, a small part of the CsX molecules (+ cation coordination type variation in the series from Li+ to Cs+ are discussed in connection with changes in the M+ charge density and radii. The properties of the salts and corresponding carboxylates studied are compared

  17. Negative ions in vapors of alkaline earth metal dichlorides. Enthalpy of ion formation

    International Nuclear Information System (INIS)

    Results of investigation into the negative component of Sr and Ba dichloride saturated vapors are presented. Investigations were conducted using ion-molecular equilibrium method which is one of the options of mass-spectrometry method. Cl-, SrCl3-, Sr2Cl5- ions are identified above SrCl2 within 1000-1300 K temperature interval. Based on obtained experimental values and literary data SrCl3- and Sr2Cl5- gaseous ion formation enthalpies, making up respectively -1008±15 and -1769±30 kJ/mol, at 0 K are calculated. 25 refs.; 1 fig.; 4 tabs

  18. Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

    2015-03-28

    This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

  19. Inverse Problems in Complex Models and Applications to Earth Sciences

    Science.gov (United States)

    Bosch, M. E.

    2015-12-01

    The inference of the subsurface earth structure and properties requires the integration of different types of data, information and knowledge, by combined processes of analysis and synthesis. To support the process of integrating information, the regular concept of data inversion is evolving to expand its application to models with multiple inner components (properties, scales, structural parameters) that explain multiple data (geophysical survey data, well-logs, core data). The probabilistic inference methods provide the natural framework for the formulation of these problems, considering a posterior probability density function (PDF) that combines the information from a prior information PDF and the new sets of observations. To formulate the posterior PDF in the context of multiple datasets, the data likelihood functions are factorized assuming independence of uncertainties for data originating across different surveys. A realistic description of the earth medium requires modeling several properties and structural parameters, which relate to each other according to dependency and independency notions. Thus, conditional probabilities across model components also factorize. A common setting proceeds by structuring the model parameter space in hierarchical layers. A primary layer (e.g. lithology) conditions a secondary layer (e.g. physical medium properties), which conditions a third layer (e.g. geophysical data). In general, less structured relations within model components and data emerge from the analysis of other inverse problems. They can be described with flexibility via direct acyclic graphs, which are graphs that map dependency relations between the model components. Examples of inverse problems in complex models can be shown at various scales. At local scale, for example, the distribution of gas saturation is inferred from pre-stack seismic data and a calibrated rock-physics model. At regional scale, joint inversion of gravity and magnetic data is applied

  20. VCD Studies on Chiral Characters of Metal Complex Oligomers

    OpenAIRE

    Hisako Sato; Akihiko Yamagishi

    2013-01-01

    The present article reviews the results on the application of vibrational circular dichroism (VCD) spectroscopy to the study of stereochemical properties of chiral metal complexes in solution. The chiral characters reflecting on the vibrational properties of metal complexes are revealed by measurements of a series of β-diketonato complexes with the help of theoretical calculation. Attention is paid to the effects of electronic properties of a central metal ion on vibrational energy l...

  1. Rare earth metals. Lanthanides and third subgroup. A journey through the periodic table

    International Nuclear Information System (INIS)

    Hermann Sicius brings the reader concisely near all the important information about an important class of metallic raw materials. The eighteen metals of the lanthanides (rare earth metals) and the third subgroup are known only to a small part of the public, but of great importance for many future technologies.

  2. Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)

    Energy Technology Data Exchange (ETDEWEB)

    Juergens, Barbara; Irran, Elisabeth; Schnick, Wolfgang

    2001-03-01

    The alkaline earth dicyanamides Mg[N(CN){sub 2}]{sub 2}, Ca[N(CN){sub 2}]{sub 2}, Sr[N(CN){sub 2}]{sub 2}, and Ba[N(CN){sub 2}]{sub 2} were synthesized by ion exchange using Na[N(CN){sub 2}] and the respective nitrates or bromides as starting materials. The crystal structures were determined from X-ray powder diffractometry: Mg[N(CN){sub 2}]{sub 2}, Pnnm, Z=2, a=617.14(3), b=716.97(3), and c=740.35(5) pm; Ca[N(CN){sub 2}]{sub 2} and Sr[N(CN){sub 2}]{sub 2}, C2/c, Z=4; Ca[N(CN){sub 2}]{sub 2}, a=1244.55(3), b=607.97(1), and c=789.81(1) pm, {beta}=98.864(2){degree}; Sr[N(CN){sub 2}]{sub 2}, a=1279.63(2), b=624.756(8), and c=817.56(1) pm, {beta}=99.787(1){degree}; Ba[N(CN){sub 2}]{sub 2}, Pnma, Z=4, a=1368.68(7), b=429.07(7), and c=1226.26(2) pm. The dicyanamides consist of the respective alkaline earth cations and bent planar [N(CN){sub 2}]{sup -} ions. The structural features were correlated with vibrational spectroscopic data. The thermal behavior was studied by thermoanalytical experiments.

  3. Coordination and ion-ion interactions of chromium centers in alkaline earth zinc borate glasses probed by electron paramagnetic resonance and optical spectroscopy

    Science.gov (United States)

    Sumalatha, B.; Omkaram, I.; Rajavardana Rao, T.; Linga Raju, Ch

    2013-05-01

    Electron paramagnetic resonance (EPR), optical absorption and FT-IR studies have been carried out on chromium ions incorporated in alkaline earth zinc borate glasses. The EPR spectra exhibit two resonance signals with effective g values at g ≈ 1.99 and ≈1.97. The resonance signal at g ≈ 1.99 is attributed to the contribution from both the exchange coupled Cr3+-Cr3+ ion pairs and the isolated Cr3+ ions and the resonance signal at g ≈ 1.97 is due to Cr5+ ions. The paramagnetic susceptibility (χ) was calculated from the EPR data at various (123-303 K) temperatures and the Curie temperature (θp) was calculated from the 1/χ-T graph. The optical absorption spectra exhibit three bands at ˜360 nm, ˜440 nm and a broad band at ˜615 nm characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal-field splitting parameter Dq and the Racah parameters (B and C) have been evaluated. From the ultraviolet edges, the optical band gap energies (Eopt) and Urbach energy (ΔE) are calculated. The theoretical optical basicity (Λth) of these glasses has also been evaluated. Chromium ions doped alkaline earth zinc borate glasses show BO3 and BO4 structural units in the FT-IR studies.

  4. Coordination and ion–ion interactions of chromium centers in alkaline earth zinc borate glasses probed by electron paramagnetic resonance and optical spectroscopy

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR), optical absorption and FT-IR studies have been carried out on chromium ions incorporated in alkaline earth zinc borate glasses. The EPR spectra exhibit two resonance signals with effective g values at g ≈ 1.99 and ≈1.97. The resonance signal at g ≈ 1.99 is attributed to the contribution from both the exchange coupled Cr3+–Cr3+ ion pairs and the isolated Cr3+ ions and the resonance signal at g ≈ 1.97 is due to Cr5+ ions. The paramagnetic susceptibility (χ) was calculated from the EPR data at various (123–303 K) temperatures and the Curie temperature (θp) was calculated from the 1/χ–T graph. The optical absorption spectra exhibit three bands at ∼360 nm, ∼440 nm and a broad band at ∼615 nm characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal-field splitting parameter Dq and the Racah parameters (B and C) have been evaluated. From the ultraviolet edges, the optical band gap energies (Eopt) and Urbach energy (ΔE) are calculated. The theoretical optical basicity (Λth) of these glasses has also been evaluated. Chromium ions doped alkaline earth zinc borate glasses show BO3 and BO4 structural units in the FT-IR studies. (paper)

  5. Enhanced Structural Support of Metal Sites as Nodes in Metal-Organic Frameworks Compared to Metal Complexes

    OpenAIRE

    Das, Sanjit

    2013-01-01

    Metal-organic frameworks are a new class of crystalline, porous solid-state materials with metal ions periodically linked by organic linkers. This gives rise to one-, two- or three-dimensional structures. Here, we compare the stability of similar metal sites toward external ligand (solvent) induced disruption of the coordination environment in metal complexes and in metal-organic frameworks. Our experimental results show that a metal site as node of a metal-organic framework retains much high...

  6. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of ico-sahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  7. Evaluation of metal oxide and carbonate nanoparticle stability in soybean oil: Implications for controlled release of alkalinity during subsurface remediation

    Science.gov (United States)

    Ramsburg, C. A.; Leach, O. I.; Sebik, J.; Muller, K.

    2011-12-01

    Traditional methods for adjusting groundwater pH rely on injection of aqueous solutes and therefore, amendment distribution is reliant upon aqueous phase flow and transport. This reliance can limit mixing and sustention of amendments within the treatment zone. Oil-in-water emulsions offer an alternative for amendment delivery - one that has potential to enhance control of the distribution and release of buffering agents within the subsurface. Focus here is placed on using metal oxide and carbonate nanoparticles to release alkalinity from soybean oil, a common dispersed phase within emulsions designed to support remediation activities. Batch reactor systems were employed to examine the influence of dispersed phase composition on particle stability and solubility. The stability of uncoated MgO and CaCO3 particles in unmodified soybean oil was explored in a series of sedimentation studies conducted at solid loadings of 0.05, 0.1, and 0.2% mass. Three nominal sizes of MgO particles were examined (20, 50, and 100 nm) and one CaCO3 particle size (60 nm). Results from sedimentation studies conducted over four hours suggest that the viscosity of the soybean oil imparts a kinetic stability, for all sizes of the uncoated MgO and CaCO3 nanoparticles, which is sufficient time for particle encapsulation within oil-in-water emulsions. Based upon these results, the sedimentation of the 50 nm and 100 nm MgO, and 60 nm CaCO3 particles was assessed over longer durations (≥72 hr). Results from these stability tests suggest that the 50 nm and 100 nm MgO particles have greater kinetic stability than the 60 nm CaCO3. Batch studies were also used to assess the influence of n-butanol, a co-solvent hypothesized to aid in controlling the rate of alkalinity release, on phase behavior and metal (Mg2+ and Ca2+) solubility. Phase behavior studies suggest that n-butanol has a limited region of miscibility within the soybean oil-water system. Use of n-butanol and water within this region of

  8. Sequential Washing with Electrolyzed Alkaline and Acidic Water Effectively Removes Pathogens from Metal Surfaces.

    Science.gov (United States)

    Nakano, Yuichiro; Akamatsu, Norihiko; Mori, Tsuyoshi; Sano, Kazunori; Satoh, Katsuya; Nagayasu, Takeshi; Miyoshi, Yoshiaki; Sugio, Tomomi; Sakai, Hideyuki; Sakae, Eiji; Ichimiya, Kazuko; Hamada, Masahisa; Nakayama, Takehisa; Fujita, Yuhzo; Yanagihara, Katsunori; Nishida, Noriyuki

    2016-01-01

    Removal of pathogenic organisms from reprocessed surgical instruments is essential to prevent iatrogenic infections. Some bacteria can make persistent biofilms on medical devices. Contamination of non-disposable equipment with prions also represents a serious risk to surgical patients. Efficient disinfection of prions from endoscopes and other instruments such as high-resolution cameras remains problematic because these instruments do not tolerate aggressive chemical or heat treatments. Herein, we develop a new washing system that uses both the alkaline and acidic water produced by electrolysis. Electrolyzed acidic water, containing HCl and HOCl as active substances, has been reported to be an effective disinfectant. A 0.15% NaCl solution was electrolyzed and used immediately to wash bio-contaminated stainless steel model systems with alkaline water (pH 11.9) with sonication, and then with acidic water (pH 2.7) without sonication. Two bacterial species (Staphylococcus aureus and Pseudomonas aeruginosa) and a fungus (Candida albicans) were effectively removed or inactivated by the washing process. In addition, this process effectively removed or inactivated prions from the stainless steel surfaces. This washing system will be potentially useful for the disinfection of clinical devices such as neuroendoscopes because electrolyzed water is gentle to both patients and equipment and is environmentally sound. PMID:27223116

  9. Sequential Washing with Electrolyzed Alkaline and Acidic Water Effectively Removes Pathogens from Metal Surfaces.

    Directory of Open Access Journals (Sweden)

    Yuichiro Nakano

    Full Text Available Removal of pathogenic organisms from reprocessed surgical instruments is essential to prevent iatrogenic infections. Some bacteria can make persistent biofilms on medical devices. Contamination of non-disposable equipment with prions also represents a serious risk to surgical patients. Efficient disinfection of prions from endoscopes and other instruments such as high-resolution cameras remains problematic because these instruments do not tolerate aggressive chemical or heat treatments. Herein, we develop a new washing system that uses both the alkaline and acidic water produced by electrolysis. Electrolyzed acidic water, containing HCl and HOCl as active substances, has been reported to be an effective disinfectant. A 0.15% NaCl solution was electrolyzed and used immediately to wash bio-contaminated stainless steel model systems with alkaline water (pH 11.9 with sonication, and then with acidic water (pH 2.7 without sonication. Two bacterial species (Staphylococcus aureus and Pseudomonas aeruginosa and a fungus (Candida albicans were effectively removed or inactivated by the washing process. In addition, this process effectively removed or inactivated prions from the stainless steel surfaces. This washing system will be potentially useful for the disinfection of clinical devices such as neuroendoscopes because electrolyzed water is gentle to both patients and equipment and is environmentally sound.

  10. Sequential Washing with Electrolyzed Alkaline and Acidic Water Effectively Removes Pathogens from Metal Surfaces

    Science.gov (United States)

    Nakano, Yuichiro; Akamatsu, Norihiko; Mori, Tsuyoshi; Sano, Kazunori; Satoh, Katsuya; Nagayasu, Takeshi; Miyoshi, Yoshiaki; Sugio, Tomomi; Sakai, Hideyuki; Sakae, Eiji; Ichimiya, Kazuko; Hamada, Masahisa; Nakayama, Takehisa; Fujita, Yuhzo; Yanagihara, Katsunori; Nishida, Noriyuki

    2016-01-01

    Removal of pathogenic organisms from reprocessed surgical instruments is essential to prevent iatrogenic infections. Some bacteria can make persistent biofilms on medical devices. Contamination of non-disposable equipment with prions also represents a serious risk to surgical patients. Efficient disinfection of prions from endoscopes and other instruments such as high-resolution cameras remains problematic because these instruments do not tolerate aggressive chemical or heat treatments. Herein, we develop a new washing system that uses both the alkaline and acidic water produced by electrolysis. Electrolyzed acidic water, containing HCl and HOCl as active substances, has been reported to be an effective disinfectant. A 0.15% NaCl solution was electrolyzed and used immediately to wash bio-contaminated stainless steel model systems with alkaline water (pH 11.9) with sonication, and then with acidic water (pH 2.7) without sonication. Two bacterial species (Staphylococcus aureus and Pseudomonas aeruginosa) and a fungus (Candida albicans) were effectively removed or inactivated by the washing process. In addition, this process effectively removed or inactivated prions from the stainless steel surfaces. This washing system will be potentially useful for the disinfection of clinical devices such as neuroendoscopes because electrolyzed water is gentle to both patients and equipment and is environmentally sound. PMID:27223116

  11. Synthesis and Characterization of Rare Earth Solid Complexes with Sodium 5-Aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiuying; Li Shujing; Lei Xuefeng; Ma Junxian

    2005-01-01

    Ten new rare earth solid complexes were synthesized by the reaction of sodium 5-aminosalicyliate with rare earth chloride. The structure character, physical and chemical properties of these complexes were studied by IR, UV, 1H NMR spectra, TG-DTA, fluorescence, elemental analyses, molar conductance and magnetic susceptibility. The ten rare earth complexes exist in dimeric form probably and the coordination number is seven. The antibacterial activity of the ligand and six complexes was also tested against Staphylococcus aureus, Escherichia coli and Bacillus subtilis, and the effect of Yb complex at 20 mg·ml-1 against Staphylococcus aureus is most significant.

  12. Solubility of ion and trace metals from stabilized sewage sludge by fly ash and alkaline mine tailing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongling; SUN Lina; SUN Tieheng

    2008-01-01

    Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil,to be applied on the ecological rehabilitation at mining junkyards,offers a potentially viable utilization of the industrial by-product,as well as solves the shortage of soil resource in the mine area.An incubation experiment with different ratios of SS and FA was conducted to evaluate the solubility of ions and trace elements from stabilized sewage sludge.Results showed that fly ash offset a decrease in pH value of sewage sludge.The pH of (C) treatment (FA:SS=1:1) was stable and tended to neutrality.The SO42- and Cl- concentrations of the solution in the mixture were significantly decreased in the stabilized sewage sludge by alkaline fly ash and mine tailing,compared to the single SS treatment.Stabilized sewage sludge by FA weakened the nitrification of total nitrogen from SS when the proportion of FA in the mixture was more than 50%.The Cr,Ni,and Cu concentrations in the solution were gradually decreased and achieved a stable level after 22 days,for all treatments over the duration of the incubation.Moreover stabilized sewage sludge by fly ash and/or mine tailing notably decreased the trace metal solubility.The final Cr,Cu,and Ni concentrations in the solution for all mixtures of treatments were lower than 2.5,15,and 50 μg/L,respectively.

  13. Discovery of an alkaline ortho gneiss in the eclogite-bearing Cellier unit (Champtoceaux complex, Armorican Massif): a new witness of the ordovician rifting

    International Nuclear Information System (INIS)

    An alkaline orthogneiss from the Lower allochthon of the Champtoceaux Complex has been identified by its mineralogy and its whole-rock chemistry, including trace elements and Sr and Nd isotopes. An U/Pb study of the zircons using the conventional method gives an upper intercept age of 481 +6/-5 Ma. The alkaline orthogneiss is thus a new witness of the Ordovician rifting in the Variscan Belt. (authors)

  14. Mechanism of effect of rare earth oxides on high temperature corrosion resistance of weld metal

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-yong; WANG Bao; ZHANG Han-qian

    2006-01-01

    Through the addition of rare earth oxides into the coating of electrodes, the high temperature oxidation and sulphidation resistance of weld metal were studied. The transfer mechanism of rare earth oxides from coating to the welding pool and the physicochemical reaction during the process were analyzed. With the application of scanning electron microscope and energy spectrometer, the mechanism of weld metal corrosion in air and sulphur environment were studied. The result shows that the addition of rare earth oxides can improve the high temperature resistance of weld metal, especially in sulphidation environment. The electrodes in which La2O3 is added have better performance than the electrodes in which CeO2 is added. The existence form and distribution characteristic of rare earth are defined. It is believed that the marked effect of rare earth oxides in sulphur environment is related to the corrosion mechanism.

  15. CATALYTIC ACTIVITIES OF RARE-EARTH CALIXARENE COMPLEXES IN POLYMER SYNTHESES

    Institute of Scientific and Technical Information of China (English)

    Zhi-quan Shen

    2005-01-01

    The studies of our group on the catalytic activities of rare earth calixarene complexes in polymer syntheses are reviewed. Rare earth calixarene complexes are effect catalysts for the polymerizations of butadiene, isoprene, ethylene,styrene, propylene oxide, styrene oxide, trimethylene carbonate and 2,2-dimethyl-trimethylene carbonate.

  16. Construction of embedded-atom-method interatomic potentials for alkaline metals (Li, Na, and K) by lattice inversion

    International Nuclear Information System (INIS)

    The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li, Na, and K. It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials, especially for the prediction of surface energy. The lattice-inversion embedded-atom-method interatomic potentials for Li, Na, and K are successfully constructed by taking the fourth-neighbor atoms into consideration. These angular-independent potentials markedly promote the accuracy of predicted surface energies, which agree well with experimental results. In addition, the predicted structural stability, elastic constants, formation and migration energies of vacancy, and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations, and the equilibrium condition is satisfied. (atomic and molecular physics)

  17. Construction of embedded-atom-method interatomic potentials for alkaline metals (Li, Na, and K) by lattice inversion

    Institute of Scientific and Technical Information of China (English)

    Yuan Xiao-Jian; Chen Nan-Xian; Shen Jiang

    2012-01-01

    The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li,Na,and K.It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials,especially for the prediction of surface energy.The lattice-inversion embedded-atom-method interatomic potentials for Li,Na,and K are successfully constructed by taking the fourth-neighbor atoms into consideration.These angular-independent potentials markedly promote the accuracy of predicted surface energies,which agree well with experimental results.In addition,the predicted structural stability,elastic constants,formation and migration energies of vacancy,and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations,and the equilibrium condition is satisfied.

  18. Process optimization and kinetics for leaching of rare earth metals from the spent Ni-metal hydride batteries.

    Science.gov (United States)

    Meshram, Pratima; Pandey, B D; Mankhand, T R

    2016-05-01

    Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features. PMID:26746588

  19. Adsorption of rare earth metal ion by algae. Sorui ni yoru kidorui ion no kyuchaku

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, T.; Yazawa, A. (Miyagi National College of Technology, Miyagi (Japan))

    1994-02-25

    This paper reports the result of investigations on adsorption of rare earth metal ion by using algae, and adsorption of different metal ions by using egg white and soy bean protein. Rare earth metal ion is adsorbed at a considerably high rate with alga powder of different kinds. The adsorption has been judged to be cation exchange reactive adsorption, while with use of spirulina and chlorella a maximum value of adsorption rate has been observed at pH from 3 to 4.5. Therefore, selective adsorption and separation of metal ions other than rare earth metal ion has become possible. When the blue pigment extracted from spirulina, the spirulina blue, is used, the rare earth metal ion had its selective adsorption and separation performance improved higher than using spirulina itself at pH from 3 to 4.5. As a result of adsorption experiment using egg white and soy bean protein, it has been found that the metal ion adsorption behavior of the spirulina blue depends on coagulative action of protein structure to some extent. However, the sharp selective adsorption performance on rare earth metal ion due to particular pH strength has been found because of actions unique to the pigment structure of phycocyanin, a major component in the spirulina blue. 7 refs., 19 figs.

  20. Comparative investigation on the effect of alkaline earth oxides on the intensity of absorption bands due to Cu2+, Mn3+ and Cr3+ ions in ternary silicate glasses

    Indian Academy of Sciences (India)

    S P Singh; Aman; Anal Tarafder

    2004-06-01

    Absorption characteristics of Cu2+, Mn3+ and Cr3+ ions in ternary silicate (20Na2O.10RO.70SiO2, where R=Ca, Sr, Ba) glasses were investigated. The intensities of absorption bands due to Cu2+ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case of Mn3+ and Cr3+ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu2+, Mn3+ and Cr3+ ion is attributed due to change in silicate glass compositions.

  1. Optimization of low-temperature alkaline smelting process of crushed metal enrichment originated from waste printed circuit boards

    Institute of Scientific and Technical Information of China (English)

    GUO Xue-yi; LIU Jing-xin

    2015-01-01

    A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters, in which mass ratio of NaOH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and 3D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of 80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of NaOH-to-CME of 4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.

  2. New rare-earth quinolinate complexes for organic light-emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, H. [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil); Paolini, T.B. [Chemistry Institute, Department of Fundamental Chemistry, University of São Paulo, USP, 05599-970 São Paulo (Brazil); Niyama, E. [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil); Brito, H.F. [Chemistry Institute, Department of Fundamental Chemistry, University of São Paulo, USP, 05599-970 São Paulo (Brazil); Cremona, M., E-mail: cremona@fis.puc-rio.br [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil)

    2013-01-01

    Because of its thermal and morphological stability and optical and electrical properties, tris(8-hydroxyquinoline) aluminum (Alq{sub 3}) is one of the most widely used electron transporting materials in organic light-emitting devices (OLEDs). The search for substitutes for this compound constitutes an important field of research in organic electronics. We report on a study of a new rare-earth tetrakis 8-hydroxyquinoline complex. Synthesis of tris complexes with rare-earth metals and 8-hydroxyquinoline resulted in unstable compounds. However, the inclusion of an additional quinoline group stabilized these compounds. Li[RE(q){sub 4}] (where RE = La{sup 3+}, Lu{sup 3+} and Y{sup 3+} and q = 8-hydroxyquinoline) were synthesized and then used as the electron-transporting and emitting layer in OLEDs. Thin films were deposited in a high-vacuum environment by thermal evaporation on quartz and silicon substrates. Optical characterization of the RE complexes revealed emission in the 510–525 nm range, the same as that observed for Alq{sub 3}, while absorption was observed at wavelengths of 382 nm for the Y/La complexes and 388 nm for the Lu complex. The OLEDs were fabricated with an indium tin oxide layer (ITO) as the anode, (N,N′-bis (1-naphtyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine) NPB as the hole-transporting layer (25 nm), Li[RE(q){sub 4}] as the electron-transporting and emitting layer (40 nm) and aluminum as the cathode (120 nm). The electroluminescence (EL) spectra showed a broad band from 520 to 540 nm and green-colored emission associated with the 8-hydroxyquinoline ligand. There was an interesting dependence of the maximum energy peak position and half-width of the emission band in the EL spectra on the atomic radius of the RE ion used. The best luminance for the OLEDs produced in this study was achieved with the Li[RE(q){sub 4}] compound. The optical and electrical properties of this OLED were comparable to those of similar devices based on Alq{sub 3

  3. Thermal Low-Temperature Properties of Rare Earth Transition Metal Borocarbides

    OpenAIRE

    Lipp, Dieter

    2002-01-01

    The present work reports on thermal low-temperature properties of rare earth transition metal borocarbides such as specific heat, thermal conductivity and thermopower. The influence of structural disorder, caused by stoichiometric variations and substitutions of the rare earth element or the transition metal, on the thermal and superconducting low-temperature properties is investigated. The structural disorder results in the reduction of the superconducting transition temperature Tc, of the S...

  4. VCD Studies on Chiral Characters of Metal Complex Oligomers

    Directory of Open Access Journals (Sweden)

    Hisako Sato

    2013-01-01

    Full Text Available The present article reviews the results on the application of vibrational circular dichroism (VCD spectroscopy to the study of stereochemical properties of chiral metal complexes in solution. The chiral characters reflecting on the vibrational properties of metal complexes are revealed by measurements of a series of β-diketonato complexes with the help of theoretical calculation. Attention is paid to the effects of electronic properties of a central metal ion on vibrational energy levels or low-lying electronic states. The investigation is further extended to the oligomers of β-diketonato complex units. The induction of chiral structures is confirmed by the VCD spectra when chiral inert moieties are connected with labile metal ions. These results have demonstrated how VCD spectroscopy is efficient in revealing the static and dynamic properties of mononuclear and multinuclear chiral metal complexes, which are difficult to clarify by means of other spectroscopes.

  5. FEM study of extrusion complexity and dead metal zone

    OpenAIRE

    S.Z. Qamar

    2009-01-01

    Purpose: Quality of the extruded product and efficiency of the manufacturing process can be seriously affected by inconsistent metal flow through the extrusion die. Metal flow problems can also significantly reduce die life. Various researchers have investigated the effect of profile complexity on extrusion pressure, product quality, die life, etc. However, the relationship between shape complexity and metal flow through the extrusion die has not been studied in detail. Cold extrusion experim...

  6. The origin of increase of damping in transition metals with rare earth impurities

    OpenAIRE

    Hohlfeld, A. Rebei J.

    2006-01-01

    The damping due to rare earth impurities in transition metals is discussed in the low concentration limit. It is shown that the increase in damping is mainly due to the coupling of the orbital moments of the rare earth impurities and the conduction $p$-electrons. It is shown that an itinerant picture for the host transition ions is needed to reproduce the observed dependence of the damping on the total angular moment of the rare earths.

  7. Change of magnetic and electronic features through subtle substitution in cubic, non-centrosymmetric extended rare-earth metal cluster complexes (TR{sub 3})X{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Simon [Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln (Germany); Valldor, Martin [II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln (Germany); Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden (Germany); Meyer, Gerd, E-mail: gerd.meyer@uni-koeln.de [Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln (Germany)

    2013-10-15

    The new compound (IrCe{sub 3})I{sub 3} was synthesized by comproportionation reactions of stoichiometric ratios of CeI{sub 3}, Ce and Ir. Single crystal X-ray diffraction structure determination shows that (IrCe{sub 3})I{sub 3} crystallizes with the cubic variant of the (TR{sub 3})X{sub 3} family (I4{sub 1}32, Z=8, a=12.450(1) Å, V=1930.0(3) Å{sup 3}) and is isostructural with the recently reported (RuLa{sub 3})Br{sub 3}. Octahedral (IrCe{sub 6}) clusters share three common edges forming interpenetrating chains that run along the 4{sub 1} screw axes. Magnetic measurements on pure powder samples of (IrCe{sub 3})I{sub 3} show paramagnetic behavior and, at temperatures below 2 K, a mictomagnetic state. The isostructural (RuLa{sub 3})Br{sub 3} is a Pauli paramagnet suggesting metallic conductivity which is consistent with band structure calculations where the Fermi level is placed below a pseudogap. For (IrCe{sub 3})I{sub 3}, on the contrary, the Fermi level falls in a narrow gap rather than a pseudogap suggesting activated conductivity. - Graphical abstract: The subtle change from (RuLa{sub 3})Br{sub 3} to (IrCe{sub 3})I{sub 3} (IrCe{sub 3})I{sub 3} with the addition of one 5d and one 4f electron changes the magnetic and electronic properties dramatically; (RuLa{sub 3})Br{sub 3} is a Pauli paramagnet, (IrCe{sub 3})I{sub 3} a Langevin paramagnet with mictomagnetic behavior at very low temperatures. Display Omitted.

  8. Geologic relationships and mineralization of peralkaline/alkaline granite-syenite of the Zargat Na'am ring complex, Southeastern Desert, Egypt

    Institute of Scientific and Technical Information of China (English)

    Gehad M. Saleh

    2006-01-01

    The Zargat Na'am ring complex crops out 90 km NW of Shalatin City in the Southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. It is cut by two sets of joints and faults which strike predominantly NNW-SSE and E-W,and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. It consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills.The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFSM), such as Zr and Nb. The highest concentrations ( 1.5 wt% Zr, 0.25 wt% Nb,0.6 wt% ∑REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartzhosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750 × 10-6), Zr (2500 × 10-6) and REEs (1450 × 10-6). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions.

  9. Tolerance of Chemoorganotrophic Bioleaching Microorganisms to Heavy Metal and Alkaline Stresses

    OpenAIRE

    Annick Monballiu; Nele Cardon; Minh Tri Nguyen; Christel Cornelly; Boudewijn Meesschaert; Yi Wai Chiang

    2015-01-01

    The bioleaching potential of the bacterium Bacillus mucilaginosus and the fungus Aspergillus niger towards industrial residues was investigated by assessing their response towards various heavy metals (including arsenic, cadmium, cobalt, chromium, nickel, lead, and zinc) and elevated pH. The plate diffusion method was performed for each metal to determine the toxicity effect. Liquid batch cultures were set up for more quantitative evaluation as well as for studying the influence of basicity. ...

  10. Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements

    International Nuclear Information System (INIS)

    Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method to the rare earths and actinides, and modifications were necessary to provide accurate representation of known diagrams. To calculate the interaction parameters for rare earth-rare earth diagrams, it was necessary to use the atomic volumes for each of the phases: liquid, body-centered cubic, hexagonal close-packed, and face-centered cubic. Determination of the atomic volumes of each of these phases for each element is discussed in detail. In some cases, empirical means were necessary. Results are presented on the calculation of rare earth-rare earth, rare earth-actinide, and actinide-actinide diagrams. For rare earth-refractory transition metal diagrams and actinide-refractory transition metal diagrams, empirical means were required to develop values for the enthalpy of vaporization for rare earth elements and values for the constant (C) required when intermediate phases are present. Results of using the values determined for each element are presented

  11. Hydrogen and carbon abundances and isotopic ratios in apatite from alkaline intrusive complexes, with a focus on carbonatites

    Energy Technology Data Exchange (ETDEWEB)

    Nadeau, S.L.; Epstein, S.; Stolper, E. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences

    1999-06-01

    The authors report H and C contents and {delta}D and {delta}{sup 13}C values of apatites from 15 alkaline intrusive complexes ranging in age from 110 Ma to 2.6 Ga. Sampling focused on carbonatites, but included silicate rocks as well. Heating temperatures up to 1,500 C is needed to extract fully H{sub 2}O and CO{sub 2} from these apatites. Apatites from carbonatite-rich intrusive complexes contain 0.2--1.1 wt% H{sub 2}O and 0.05--0.70 wt% CO{sub 2}; apatites from two silicate-rich alkaline complexes with little or no carbonatite are generally poorer in both volatile components (0.1--0.2% H{sub 2}O and 0.01--0.11% CO{sub 2}). D/H ratios in apatites from these rocks are bimodally distributed. The authors suggest that the {delta}D values of group I apatites represent primitive, mantle-derived values and that the group II apatites crystallized from degassed magmas, resulting in lower H{sub 2}O contents and {delta}D values. In contrast to H{sub 2}O contents and {delta}D values, CO{sub 2} contents and {delta}{sup 13}C values of gas released at high temperatures from multiple aliquots of these apatite samples are variable. This suggests the presence of more than one C-bearing component in these apatites, one of which is proposed to be dissolved carbonate; the other could be associated with hydrocarbons.

  12. Chabazite and dolomite formation in a dolocrete profile: An example of a complex alkaline paragenesis in Lanzarote, Canary Islands

    Science.gov (United States)

    Alonso-Zarza, Ana M.; Bustamante, Leticia; Huerta, Pedro; Rodríguez-Berriguete, Álvaro; Huertas, María José

    2016-05-01

    This paper studies the weathering and soil formation processes operating on detrital sediments containing alkaline volcanic rock fragments of the Mirador del Río dolocrete profile. The profile consists of a lower horizon of removilised weathered basalts, an intermediate red sandy mudstones horizon with irregular carbonate layers and a topmost horizon of amalgamated carbonate layers with root traces. Formation occurred in arid to semiarid climates, giving place to a complex mineralogical association, including Mg-carbonates and chabazite, rarely described in cal/dolocretes profiles. Initial vadose weathering processes occurred in the basalts and in directly overlying detrital sediments, producing (Stage 1) red-smectites and dolomicrite. Dominant phreatic (Stage 2) conditions allowed precipitation of coarse-zoned dolomite and chabazite filling porosities. In Stages 3 and 4, mostly pedogenic, biogenic processes played an important role in dolomite and calcite accumulation in the profile. Overall evolution of the profile and its mineralogical association involved initial processes dominated by alteration of host rock, to provide silica and Mg-rich alkaline waters, suitable for chabazite and dolomite formation, without a previous carbonate phase. Dolomite formed both abiogenically and biogenically, but without a previous carbonate precursor and in the absence of evaporites. Dominance of calcite towards the profile top is the result of Mg/Ca decrease in the interstitial meteoric waters due to decreased supply of Mg from weathering, and increased supply of Ca in aeolian dust. Meteoric origin of the water is confirmed by C and O isotope values, which also indicate lack of deep sourced CO2. The dolocrete studied and its complex mineral association reveal the complex interactions that occur at surface during weathering and pedogenesis of basalt-sourced rocks.

  13. Change from calc-alkaline to adakitic magmatism recorded in the Early Cretaceous Darran Complex, Fiordland, New Zealand

    International Nuclear Information System (INIS)

    The Early Cretaceous Darran Complex of the Median Tectonic Zone near Milford, South Island, New Zealand, consists dominantly of biotite - two-pyroxene diorites cut by biotite-hornblende microdiorite and quartz monzodiorite dikes. The host diorite gives a 138 ± 2.9 Ma SHRIMP age on zircons, which is interpreted to be the age of igneous crystallisation. The calc-alkaline geochemistry of the host diorites and the microdiorites is attributed to melting of a mantle wedge source fluxed by slab-derived fluids. Ductile deformation (D1) of the host diorite and the microdiorite dikes took place at mid-upper amphibolite facies conditions, with extension lineations indicating a top to the NNE sense of shear. A SHRIMP age of 136 ± 1.9 Ma on zircons from a quartz monzodiorite dike injected along D1 shears is statistically indistinguishable from that of the host diorite. This suggests that D1 was synmagmatic and that subduction, during or shortly after magma emplacement, was oblique to the Gondwana margin at c. 138 Ma. The quartz monzodiorite dikes are enriched in Na2O, Al2O3, and Sr, depleted in Y, and have a distinctly adakitic geochemistry. The change in chemistry from calc-alkaline magmas to alkali-calcic adakitic magmas reflects the melting of a mafic, garnet-bearing, essentially plagioclase-free source in the root of a volcanic arc system. (auth)

  14. Metal Complexes of Quinolone Antibiotics and Their Applications: An Update

    Directory of Open Access Journals (Sweden)

    Valentina Uivarosi

    2013-09-01

    Full Text Available Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle at the 7-position, and a carbonyl oxygen atom at the 4-position quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

  15. Evaluation of phase chemistry and petrochemical aspects of Samchampi–Samteran differentiated alkaline complex of Mikir Hills, northeastern India

    Indian Academy of Sciences (India)

    Abhishek Saha; Sohini Ganguly; Jyotisankar Ray; Nilanjan Chaterjee

    2010-10-01

    The Samchampi –Samteran alkaline complex occurs as a plug-like pluton within the Precambrian granite gneisses of Mikir Hills,Assam,northeastern India and it is genetically related to Sylhet Traps.The intrusive complex is marked by dominant development of syenite within which ijolite – melteigite suite of rocks is emplaced with an arcuate outcrop pattern.Inliers of alkali pyroxenite and alkali gabbro occur within this ijolite –melteigite suite of rocks.The pluton is also traversed by younger intrusives of nepheline syenite and carbonatite.Development of sporadic,lumpy magnetite ore bodies is also recorded within the pluton.Petrographic details of the constituent lithomembers of the pluton have been presented following standard nomenclatorial rules.Overall pyroxene compositions range from diopside to aegirine augite while alkali feldspars are typically orthoclase and plagioclase in syenite corresponds to oligoclase species.Phase chemistry of nepheline is suggestive of Na-rich alkaline character of the complex.Biotite compositions are typically restricted to a uniform compositional range and they belong to ‘biotite ’field in the relevant classification scheme.Garnets (developed in syenite and melteigite)typically tend to be Ti-rich andradite,which on a closer scan can be further designated as melanites.Opaque minerals mostly correspond to magnetite.Use of Lindsley ’s pyroxene thermometric method suggests an equilibration temperature from ∼450°–600°C for melteigite/alkali gabbro and ∼400° C for syenite.Critical assessment of other thermometric methods reveals a temperature of equilibration of ∼700°–1350°C for ijolite –melteigite suite of rocks in contrast to a relatively lower equilibration temperature of ∼600° C for syenite. Geobarometric data based on pyroxene chemistry yield an equilibration pressure of 5.32 –7.72 kb for ijolite,melteigite,alkali pyroxenite,alkali gabbro and nepheline syenite.The dominant syenite member of the

  16. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes;

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...... metal atom (M2) plus two to five (BH4)− groups, i.e., M1M2(BH4)2–5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with...

  17. Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new method for corrosion protection of Al-based metal matrixcomposites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves.The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

  18. Dispersion coefficients for the interactions of the alkali and alkaline-earth ions and inert gas atoms with a graphene layer

    CERN Document Server

    Kaur, Kiranpreet; Sahoo, B K

    2015-01-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients ($C_3$s) of the alkali ions (Li$^+$, Na$^+$, K$^+$ and Rb$^+$), the alkaline-earth ions (Ca$^+$, Sr$^+$, Ba$^+$ and Ra$^+$) and the inert gas atoms (He, Ne, Ar and Kr) with a graphene layer are determined precisely within the framework of Dirac model. For these calculations, we have evaluated the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are, finally, given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at the room temperature.

  19. The addition effects of alkaline earth ions in the chemical synthesis of ɛ-Fe2O3 nanocrystals that exhibit a huge coercive field

    Science.gov (United States)

    Ohkoshi, Shin-ichi; Sakurai, Shunsuke; Jin, Jian; Hashimoto, Kazuhito

    2005-05-01

    An iron oxide/silica composite material, which was prepared by combining reverse-micelle and sol-gel techniques, exhibited a huge coercive field Hc of 20kOe (1.6×105Am-1) in our previous work. The key of this synthetic procedure was the added Ba2+ ions that created a single phase of ɛ-Fe2O3. In the present work, the addition effect of Ca2+ ions to this procedure was investigated. Consequently, rod-shape ɛ-Fe2O3 nanocrystals (40-120nm ×15-20nm) were obtained and a Hc value of 20kOe was observed. Thermodynamical analysis that considered the surface energy of nanoparticle suggested that a single ɛ-Fe2O3 phase was generated by retarding the crystal growth of Fe2O3 particles under the presence of alkaline earth ions.

  20. Identification of major metal complexing compounds in Blepharis aspera

    International Nuclear Information System (INIS)

    Verbascoside and isoverbascoside, present at 0.7% and 0.2% (w/w dryweight), were identified to be major compounds that could contribute to the metal complexation in Blepharis aspera collected in Botswana, Africa. The metallophyte B. aspera has high ability to cope with a high level of metal accumulation. The presence of metal complexing compounds and/or antioxidants can prevent oxidative reactions in lipids, proteins and DNA that take place due to the metal accumulation. On-line liquid chromatography-solid phase extraction-nuclear magnetic resonance (LC-SPE-NMR) was applied for the identification, while electrospray-mass spectrometry (ESI-MS) and UV-vis spectroscopy was used to assess whether these compounds can complex with metals. It was found that verbascoside and isoverbascoside may form complexes with nickel, iron (verbascoside only) and copper. Thus, the presence of verbascoside and isoverbascoside can explain the survival of B. aspera in mineral-rich areas