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Sample records for alkaline earth cations

  1. Modulation of cardiac ryanodine receptor channels by alkaline earth cations.

    Directory of Open Access Journals (Sweden)

    Paula L Diaz-Sylvester

    Full Text Available Cardiac ryanodine receptor (RyR2 function is modulated by Ca(2+ and Mg(2+. To better characterize Ca(2+ and Mg(2+ binding sites involved in RyR2 regulation, the effects of cytosolic and luminal earth alkaline divalent cations (M(2+: Mg(2+, Ca(2+, Sr(2+, Ba(2+ were studied on RyR2 from pig ventricle reconstituted in bilayers. RyR2 were activated by M(2+ binding to high affinity activating sites at the cytosolic channel surface, specific for Ca(2+ or Sr(2+. This activation was interfered by Mg(2+ and Ba(2+ acting at low affinity M(2+-unspecific binding sites. When testing the effects of luminal M(2+ as current carriers, all M(2+ increased maximal RyR2 open probability (compared to Cs(+, suggesting the existence of low affinity activating M(2+-unspecific sites at the luminal surface. Responses to M(2+ vary from channel to channel (heterogeneity. However, with luminal Ba(2+or Mg(2+, RyR2 were less sensitive to cytosolic Ca(2+ and caffeine-mediated activation, openings were shorter and voltage-dependence was more marked (compared to RyR2 with luminal Ca(2+or Sr(2+. Kinetics of RyR2 with mixtures of luminal Ba(2+/Ca(2+ and additive action of luminal plus cytosolic Ba(2+ or Mg(2+ suggest luminal M(2+ differentially act on luminal sites rather than accessing cytosolic sites through the pore. This suggests the presence of additional luminal activating Ca(2+/Sr(2+-specific sites, which stabilize high P(o mode (less voltage-dependent and increase RyR2 sensitivity to cytosolic Ca(2+ activation. In summary, RyR2 luminal and cytosolic surfaces have at least two sets of M(2+ binding sites (specific for Ca(2+ and unspecific for Ca(2+/Mg(2+ that dynamically modulate channel activity and gating status, depending on SR voltage.

  2. 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 +}.

  3. Competitive solvent extraction of alkaline-earth cations into chloroform by lipophilic acyclic polyether dicarboxylic acids

    International Nuclear Information System (INIS)

    Kang, S.I.; Czech, A.; Czech, B.P.; Stewart, L.E.; Bartsch, R.A.

    1985-01-01

    Competitive solvent extraction of alkaline-earth cations from aqueous solutions into chloroform by a series of lipophilic acyclic polyether dicarboxylic acids is reported. The influence of polyether chain length and of terminal carboxylic acid group variation upon extraction selectivity and efficiency is assessed. In the competitive extraction of concentrated magnesium, calcium, strontium and barium chloride solutions, one complexing agent exhibits pronounced selectivity for barium with Ba 2+ /S 2+ = 50, Ba 2+ /Ca 2+ = 250, and no detectable Mg 2+ extraction. 20 references, 3 figures, 1 table

  4. Theoretical studies on selectivity of dibenzo-18-crown-6-ether for alkaline earth divalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Jiyoung [Sangmyung Univ., Seoul (Korea, Republic of)

    2012-04-15

    Crown ether is one of well-known host molecules and able to selectively sequester metal cation. We employed M06-2X density functional theory with IEFPCM and SMD continuum solvation models to study selectivity of dibenzo-18-crown-6-ether (DB18C6) for alkaline earth dications, Ba{sup 2+}, Sr{sup 2+}, Ca{sup 2+}, and Mg{sup 2+} in the gas phase and in aqueous solution. Mg{sup 2+} showed predominantly strong binding affinity in the gas phase because of strong polarization of CO bonds by cation. In aqueous solution, binding free energy differences became smaller among these dications. However, Mg{sup 2+} had the best binding, being incompatible with experimental observations in aqueous solution. The enthalpies of the dication exchange reaction between DB18C6 and water cluster molecules were computed as another estimation of selectivity in aqueous solution. These results also demonstrated that Mg{sup 2+} bound to DB18C6 better than Ba{sup 2+}. We speculated that the species determining selectivity in water could be 2:1 complexes of two DB18C6s and one dication.

  5. Effect of alkaline earth metal and magnesium cations on cadmium extraction from chloride solutions by tributyl phosphate

    International Nuclear Information System (INIS)

    Prokuev, V.A.; Belousov, E.A.

    1985-01-01

    At 298 K thermodynamic constants of cadmium (2) extraction from chloride solutions of magnesium, calcium, strontium and barium by tributyl phosphate are calculated. It is established, that logarithm of the thermodynamic extraction constant is in a linear dependence from the change in the cation hydration enthalpy in agqueous solution. It is shown, that activity coefficient of neutral complex CdVCl 2 differs from one, and it is the higher the more stable the complex is in alkaline earth metal chloride solutions

  6. Alkaline earth metals

    International Nuclear Information System (INIS)

    Brown, Paul L.; Ekberg, Christian

    2016-01-01

    The beryllium ion has a relatively small ionic radius. As a consequence of this small size, its hydrolysis reactions begin to occur at a relatively low pH. To determine the stability and solubility constants, however, the Gibbs energy of the beryllium ion is required. In aqueous solution calcium, like the other alkaline earth metals, only exists as a divalent cation. The size of the alkaline earth cations increases with increasing atomic number, and the calcium ion is bigger than the magnesium ion. The hydrolysis of barium(II) is weaker than that of strontium(II) and also occurs in quite alkaline pH solutions, and similarly, only the species barium hydroxide has been detected. There is only a single experimental study on the hydrolysis of radium. As with the stability constant trend, it would be expected that the enthalpy of radium would be lower than that of barium due to the larger ionic radius.

  7. Separation of alkali, alkaline earth and rare earth cations by liquid membranes containing macrocyclic carriers. Third progress report, September 1, 1980-April 1, 1981

    International Nuclear Information System (INIS)

    Christensen, J.J.

    1981-01-01

    The overall objective of this project is to study the use of liquid membrane systems employing macrocyclic ligand carriers in making separations among metal cations. During the third year of the project, work continued in the development of a mathematical model to describe cation transport. The model was originally developed to describe the relationship between cation transport rate (J/sub M/) and the cation-macrocycle stability constant (K). The model was tested by determining the rates of transport of alkali and alkaline earth cations through chloroform membranes containing carrier ligands where the stability constants for their reaction with cations in methanol were known. From the results, it is clear that the model correctly describes the dependence of J/sub M/ on log K. The model also correctly describes the effect of cation concentration and carrier concentration on cation transport rates, as detailed in the previous progress report. During the third year of the project, the transport model was expanded so as to apply to competitive transport of cations from mixtures of two cations in the source aqueous phase. Data were collected under these conditions and the ability of the model to predict the flux of each cation was tested. Representative data of this type are presented along with corresponding data which were obtained when each cation was transported by the same carrier from a source phase containing only that cation. Comparison of transport rates determined under the two experimental conditions indicates that the relationship between the two sets of data is complex. To date, a few of these data involving transport from binary cation mixtures have been tested against the transport model. It was found that the model correctly predicts the cation fluxes from cation mixtures. These preliminary results indicate that the transport model can successfully predict separation factors when cation mixtures are used

  8. Ion exchange kinetics of alkaline earths on Zr(IV) arsenosilicate cation exchanger

    International Nuclear Information System (INIS)

    Varshney, K.G.; Agrawal, S.; Varshney, K.

    1984-01-01

    A new approach based on the Nernst-Planck equations was applied to study the ion exchange kinetics for the exchange reactions of Mg(II), Ca(II), Sr(II) and Ba(II) with H + -ions at various temperatures on the zirconium(IV) arsenosilicate phase. Under the conditions of particle diffusion, the rate of exchange was found to be independent of the metal ion concentration at and above 0.1 M in aqueous medium. Energy and entropy of activation were determined and found to vary linearly with the ionic radii and mobilities of alkaline earths, a unique feature observed for an inorganic ion exchanger. The results are useful for predicting the ion exchange processes occurring on the surface of an inorganic material of the type studied. (author)

  9. Ion exchange centres of sorption of alkaline and alkaline-earth cations on hydrated titanium and tin dioxides

    International Nuclear Information System (INIS)

    Denisova, T.A.; Perekhozheva, T.N.; Sharigin, L.M.; Pletnev, R.N.

    1986-01-01

    The nature of exchange centres of one- and two-charged cations on hydrated titanium and tin dioxides by means of paramagnetic resonance method is studied. The sorption of cations of Na + , Cs + , Ca 2+ was carried out at 25 and 90 deg C at ph=5.0-10.4 on samples of hydrated titanium dioxide and hydrated tin dioxide, obtained by sol gel method and calcined at 150 deg C and 300 deg C accordingly.

  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

    International Nuclear Information System (INIS)

    Kuad, P.

    2006-01-01

    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.)

  11. 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)

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

    2012-01-01

    The location of extraframework cations in Sr 2+ and Ba 2+ ion-exchanged SAPO-34 was estimated by means of 1 H and 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 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 2 adsorption performance. Highlights: ► Location of extraframework Sr 2+ or Ba 2+ cations was estimated by means of 1 H and 23 Na MAS NMR. ► Level of Sr 2+ or Ba 2+ ion exchange was limited by the presence of protons and sodium cations. ► Presence of ammonium cations in the supercages facilitated the exchange. ► Sr 2+ and Ba 2+ ion exchanged SAPOs are outstanding CO 2 adsorbents.

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

    International Nuclear Information System (INIS)

    Durand, S.

    1999-01-01

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA 4- , ethylene-diamino-tri-acetate-acetic acid EDTA(H) 3- , tetra-aza-cyclo-dodecane-tetra-acetate DOTA 4- , methylene-imidine-acetate MIDA 2- ) are reported. First, a consistent set of Lennard-Jones parameters for La 3+ , Eu 3+ and Lu 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 4- , EDTA(H) 3- , DOTA 4- and 1:2 complexes of lanthanide cations with MIDA 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 2+ vs Sr 2+ and vs Ba 2+ on the one hand, and with La 3+ vs Eu 3+ and vs Lu 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)

  13. Boson peak of alkali and alkaline earth silicate glasses: influence of the nature and size of the network-modifying cation.

    Science.gov (United States)

    Richet, Nicolas F

    2012-01-21

    The influence of the size of the alkaline earth cation on the boson peak of binary metasilicate glasses, MSiO(3) (M = Mg, Ca, Sr, Ba), has been investigated from vibrational densities of states determined by inversion of low-temperature heat capacities. As given both by C(p)/T(3) and g(ω)/ω(2), the intensity of the boson peak undergoes a 7-fold increase from Mg to Ba, whereas its temperature and frequency correlatively decrease from 18 to 10 K and from 100 to 20 cm(-1), respectively. The boson peak results from a combination of librations of SiO(4) tetrahedra and localized vibrations of network-modifying cations with non-bridging oxygens whose contribution increases markedly with the ionic radius of the alkaline earth. As a function of ionic radii, the intensity for Sr and Ba varies in the same way as previously found for alkali metasilicate glasses. The localized vibrations involving alkali and heavy alkaline earth cations appear to be insensitive to the overall glass structure. Although the new data are coherent with an almost linear relationship between the temperature of the boson peak and transverse sound velocity, pure SiO(2) and SiO(2)-rich glasses make marked exceptions to this trend because of the weak transverse character of SiO(4) librations. Finally, the universality of the calorimetric boson peak is again borne out because all data for silicate glasses collapse on the same master curve when plotted in a reduced form (C(P)∕/T(3))/(C(P)/T(3))(b) vs. T/T(b). © 2012 American Institute of Physics

  14. Pma1 is an alkali/alkaline earth metal cation ATPase that preferentially transports Na(+) and K(+) across the Mycobacterium smegmatis plasma membrane.

    Science.gov (United States)

    Ayala-Torres, Carlos; Novoa-Aponte, Lorena; Soto, Carlos Y

    2015-07-01

    Mycobacterium smegmatis Pma1 is the orthologue of M. tuberculosis P-type ATPase cation transporter CtpF, which is activated under stress conditions, such as hypoxia, starvation and response to antituberculous and toxic substances. The function of Pma1 in the mycobacterial processes across the plasma membrane has not been characterised. In this work, bioinformatic analyses revealed that Pma1 likely contains potential sites for, Na(+), K(+) and Ca(2+) binding and transport. Accordingly, RT-qPCR experiments showed that M. smegmatis pma1 transcription is stimulated by sub-lethal doses of Na(+), K(+) and Ca(2+); in addition, the ATPase activity of plasma membrane vesicles in recombinant Pma1-expressing M. smegmatis cells is stimulated by treatment with these cations. In contrast, M. smegmatis cells homologously expressing Pma1 displayed tolerance to high doses of Na(+) and K(+) but not to Ca(2+) ions. Consistently, the recombinant protein Km embedded in plasma membrane demonstrated that Ca(2+) has more affinity for Pma1 than Na(+) and K(+) ions; furthermore, the estimation of Vmax/Km suggests that Na(+) and K(+) ions are more efficiently translocated than Ca(2+). Thus, these results strongly suggest that Pma1 is a promiscuous alkali/alkaline earth cation ATPase that preferentially transports Na(+) and/or K(+) across the mycobacterial plasma membrane. Copyright © 2015 Elsevier GmbH. All rights reserved.

  15. 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.

  16. 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

    International Nuclear Information System (INIS)

    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

  17. {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.

  18. 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)

    Zhang Jianhui; Leng Yanli; Wang Yongcheng

    2013-01-01

    The reaction mechanism of the reaction N 2 O( 0 Σ + ) + CO ( 1 Σ + )→N 2 ( 1 Σ g + ) + CO 2 ( 1 Σ g + ) mediated by alkaline-earth metal oxide cations 2 MO + (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 2 CaO + can capture O from N 2 O 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 N 2 O and CO mediated by 2 MO + (M=Ca, Sr, Ba). For the former, the main reaction processes in a two-step manner to products, the 2 MO + , as a catalyzer, transports an oxygen atom from N 2 O to CO. For the latter, firstly, the N 2 O interact with the 2 MO + to form IM1, then IM1 interact with the CO to form IM2', along the reaction pathway the intermediate species convert into products 2 1MO + , N 2 and CO 2 . 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)

  19. Interactions between alkaline earth cations and oxo ligands. DFT study of the affinity of the Mg²+ cation for phosphoryl ligands.

    Science.gov (United States)

    da Costa, Leonardo Moreira; de Mesquita Carneiro, José Walkimar; Paes, Lilian Weitzel Coelho

    2011-08-01

    DFT (B3LYP/6-31+G(d)) calculations of Mg(2+) affinities for a set of phosphoryl ligands were performed. Two types of ligands were studied: a set of trivalent [O = P(R)] and a set of pentavalent phosphoryl ligands [O = P(R)(3)] (R = H, F, Cl, Br, OH, OCH(3), CH(3), CN, NH(2) and NO(2)), with R either bound directly to the phosphorus atom or to the para position of a phenyl ring. The affinity of the Mg(2+) cation for the ligands was quantified by means of the enthalpy for the substitution of one water molecule in the [Mg(H(2)O)(6)](2+) complex for a ligand. The enthalpy of substitution was correlated with electronic and geometric parameters. Electron-donor groups increase the interaction between the cation and the ligand, while electron-acceptor groups decrease the interaction enthalpy.

  20. Association of alkali and alkaline earth metal cations with radical-anions of 9-fluorenone and 9.10-anthraquinone in dimethyl formamide medium

    International Nuclear Information System (INIS)

    Karpinets, A.P.; Bezuglyj, V.D.; Svetlichnaya, T.M.

    1988-01-01

    The polarographic method is used to estimate the stability of associates formed in dimethyl formamide by the products of one-electron reduction of 9-fluorenone and 9.10-anthraquinone with cations of alkali and alkali earth metals. It is shown that the strength of 9-fluorenone and 9.10-anthraquinone radical anion associates studied increases with cation charge increase and decrease of its crystallographic radius

  1. Interaction between alkaline earth cations and oxo-ligands. DFT study of the affinity of the Ca2+ cation for carbonyl ligands.

    Science.gov (United States)

    da Costa, Leonardo Moreira; Carneiro, José Walkimar de Mesquita; Romeiro, Gilberto Alves; Paes, Lilian Weitzel Coelho

    2011-02-01

    The affinity of the Ca(2+) ion for a set of substituted carbonyl ligands was analyzed with both the DFT (B3LYP/6-31+G(d)) and semi-empirical (PM6) methods. Two types of ligands were studied: a set of monosubstituted [O=CH(R)] and a set of disubstituted ligands [O=C(R)(2)] (R=H, F, Cl, Br, OH, OCH(3), CH(3), CN, NH(2) and NO(2)), with R either directly bound to the carbonyl carbon atom or to the para position of a phenyl ring. The interaction energy was calculated to quantify the affinity of the Ca(2+) cation for the ligands. Geometric and electronic parameters were correlated with the intensity of the metal-ligand interaction. The electronic nature of the substituent is the main parameter that determines the interaction energy. Donor groups make the interaction energy more negative (stabilizing the complex formed), while acceptor groups make the interaction energy less negative (destabilizing the complex formed).

  2. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    ... devices; radiation shields, surgical lasers and their glass ceramic counter ... Alkaline earth oxides improve glass forming capability while heavy metal ... reports on optical properties of MO-B2O3 glasses containing alkaline earth oxides.

  3. 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.)

  4. Progress of research on the influence of alkaline cation and alkaline solution on bentonite properties

    International Nuclear Information System (INIS)

    Ye Weimin; Zheng Zhenji; Chen Bao; Chen Yonggui

    2011-01-01

    Based on the previous laboratory studies and numerical simulation on bentonite in alkaline environments, the effects of alkaline cation and alkaline solution on mineral composition, microstructure, swelling capacity and hydraulic properties of bentonite are emphasized in this paper, temperature, pH values and concentration are discussed as main affecting factors. When bentonite is exposed to alkaline cation or alkaline solution, microstructure of bentonite will be changed due to the dissolution of montmorillonite and the formation of secondary minerals, which results in the decrease of swelling pressure. The amount of the reduction of swelling pressure depends on the concentration of alkaline solution. Temperature, polyvalent cation, salinity and concentration are the main factors affecting hydraulic properties of bentonite under alkaline conditions. Therefore, future research should focus on the mechanism of coupling effects of weak alkaline solutions on the mineral composition, microstructure, swelling capacity and hydraulic properties of bentonite under different temperatures and different pH values. (authors)

  5. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  6. Comparison of arsenic acid with phosphoric acid in the interaction with a water molecule and an alkali/alkaline-earth metal cation.

    Science.gov (United States)

    Park, Sung Woo; Kim, Chang Woo; Lee, Ji Hyun; Shim, Giwoong; Kim, Kwang S

    2011-10-20

    Recently, Wolfe-Simon has discovered a bacterium which is able to survive using arsenic(V) rather than phosphorus(V) in its DNA. Thus it is important to investigate some important structural and chemical similarities and dissimilarities between phosphate and arsenate. We compared the monohydrated structures and the alkali/alkaline-earth metal (Na(+), K(+), Mg(2+) and Ca(2+)) complexes of the arsenic acid/anions with those of the phosphoric acid/anions [i.e., H(m)PO(4)(-(3-m)) vs H(m)AsO(4)(-(3-m)) (m = 1-3)]. We carried out geometry optimization along with harmonic frequency calculations using ab initio calculations. Despite the increased van der Waals radius of As, the hydrated structures of both P and As systems show very close similarity (within 0.25 Å in the P/As···O(water) distance and within a few kJ/mol in binding energy) because of the increased induction energies by more polar arsenic acid/anons and slightly increased dispersion energy by a larger size of the As atom. In the metal complexes, the arsenic acid has a slightly larger binding distance (by 0.07-1.0 Å) and weaker binding energy because the As(V) ion has a slightly larger radius than the P(V) ion, and the electrostatic interaction is the dominating feature in these systems.

  7. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    The alkaline earth borate glasses containing heavy metal oxides show good solubility of rare-earth ions. Glasses containing PbO exhibit low glass transition temperature (Tg) and high ..... These oxygen ions carry a partial negative charge and.

  8. 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)

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

    International Nuclear Information System (INIS)

    Ulrich, J.

    1987-01-01

    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 [fr

  10. Mixed cationic dicarbides of the lanthanides, alkali and alkaline earth metals. Crystal structures and phase transformations; Gemischtkationische Dicarbide der Lanthanoide, Alkali- und Erdalkalimetalle. Kristallstrukturen und Phasenumwandlungen

    Energy Technology Data Exchange (ETDEWEB)

    Busch, Stefanie

    2015-01-27

    The work within presents the synthesis and characterization of two new solid solutions: Eu{sub x}Ba{sub 1-x}C{sub 2} and Yb{sub x}Ba{sub 1-x}C{sub 2}. The synthesis is based upon previously known solid solutions Ln{sub x}EA{sub 1-x}C{sub 2} such as Eu{sub x}Ca{sub 1-x}C{sub 2} prepared by Link. This solid solution was reproduced and fully characterized in this study. To investigate the structural characteristics of the solid solutions Eu{sub x}Ca{sub 1-x}C{sub 2} as well as the already known series Yb{sub x}Sr{sub 1-x}C{sub 2} and Yb{sub x}Eu{sub 1-x}C{sub 2} in more detail, selected compounds were investigated by temperature-dependent synchrotron powder diffraction, with structural characterization carried out using Rietveld refinements. All compounds crystallize in the known structure types of CaC{sub 2}: CaC{sub 2}-I (I4/mmm), CaC{sub 2}-II (ThC{sub 2} type, C2/c), CaC{sub 2}-III (C2/m) and CaC{sub 2}-IV (Fm anti 3m). The results suggest that the formation of a complete solid solution or the formation of a miscibility gap is preferred to the formation of new ternary compounds. The results were summarized and compared with literature, whilst similarities and differences were worked out and then placed in relation to each other. The occurrence of various structure types, which form a complete solid solution series as well as the occurrence of a miscibility gap are dependent on the mole fraction x, the temperature, the difference of the ionic radii, the type of cations and the difference of the lattice parameters. The investigated solid solutions were tested if Vegards law was obeyed, and the factors that result in deviations were determined. It was found that miscibility gaps as well as valence changes are the main reasons for deviations from Vegards law. Three different ways to decrease the lattice strain in the solid solutions were observed: decrease of the phase Transition temperatures, valence changes of lanthanide cations and formation of a miscibility gap

  11. 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.

  12. Oxidation catalysts on alkaline earth supports

    Science.gov (United States)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  13. 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)

    Verma, Poonam; Rastogi, R.K.; Ramakumar, K.L.

    2006-12-01

    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 NH 4 + along with alkali and alkaline earth cations by IC using a cation exchange column. (author)

  14. Spectroscopic characterization of alkaline earth uranyl carbonates

    International Nuclear Information System (INIS)

    Amayri, Samer; Reich, Tobias; Arnold, Thuro; Geipel, Gerhard; Bernhard, Gert

    2005-01-01

    A series of alkaline uranyl carbonates, M[UO 2 (CO 3 ) 3 ].nH 2 O (M=Mg 2 , Ca 2 , Sr 2 , Ba 2 , Na 2 Ca, and CaMg) was synthesized and characterized by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after nitric acid digestion, X-ray powder diffraction (XRD), and thermal analysis (TGA/DTA). The molecular structure of these compounds was characterized by extended X-ray absorption fine-structure (EXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). Crystalline Ba 2 [UO 2 (CO 3 ) 3 ].6H 2 O was obtained for the first time. The EXAFS analysis showed that this compound consists of (UO 2 )(CO 3 ) 3 clusters similar to the other alkaline earth uranyl carbonates. The average U-Ba distance is 3.90+/-0.02A.Fluorescence wavelengths and life times were measured using time-resolved laser-induced fluorescence spectroscopy (TRLFS). The U-O bond distances determined by EXAFS, TRLFS, XPS, and Raman spectroscopy agree within the experimental uncertainties. The spectroscopic signatures observed could be useful for identifying uranyl carbonate species adsorbed on mineral surfaces

  15. Ethylenediaminetetraacetates of neodymium and alkaline earth metals

    International Nuclear Information System (INIS)

    Barinov, A.V.; Pechurova, L.I.; Martynenko, K.I.; Popov, K.I.; Spitsyn, V.I.

    1977-01-01

    The possibilities have been studied of the formation of polynuclear complexonates of alkaline-earth metals (Ca, Sr, and Ba) based on neodymium derivatives EDTA of the composition NdA - . By pH-metry, electron spectroscopy, and derivatography it has been shown that the structure of complexes M 2 (NdA) 2 (where M- Ca, Sr, or Ba; A- EDTA) in the solution is not polynuclear. Hydroxopolynuclear complexes do not form under conditions studied. The data obtained agree with an assumption about polynuclear structure of the solid complex Ca(NdA) 2 x17 H 2 O and gradual weakening of the polynuclear nature upon substitution of Ca 2+ with Sr 2+ and Ba 2+

  16. Retention of alkaline earth elements in man

    International Nuclear Information System (INIS)

    Newton, D.

    1990-06-01

    The data on human metabolism and long-term retention of alkaline earth elements ( 133 Ba injected into six healthy male volunteers at age 25-81 y and 45 Ca and 85 Sr 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 133 Ba 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

  17. Structure of fluoroantimonates (5) and fluorobismuthates (5) of alkaline earth metals

    International Nuclear Information System (INIS)

    Popov, A.I.; Val'kovskij, M.D.; Sukhoverkhov, V.F.

    1990-01-01

    Structure of fluoroantimonates (5) and fluorobismuthates (5) of M 2+ (M 5+ F 6 ) 2 composition, where M 5+ =Sb, Bi; M 2+ =Ca, Mg, Sr, Ba, alkaline earth elements is studied using powder x-ray structure analysis. Strontium fluoroantimonate and fluorobismuthate are crystallized in triclinic syngony, lattice parameters are presented. Models of structure of the studied fluorocomplex, which crystaline lattices consist of M 2+ cations and M 5+ F 6 - octahedral anions

  18. Spectroscopic characterization of manganese-doped alkaline earth ...

    Indian Academy of Sciences (India)

    The shapes of spectra are also changed with varying alkaline earth ions content. ... of manganese ion and electrical properties of glass contain- ing mobile ions like .... octahedral crystal field are located above the ground 6S state. Figure 2.

  19. Cationic Polymers Developed for Alkaline Fuel Cell Applications

    Science.gov (United States)

    2015-01-20

    into five categories: proton exchange membrane fuel cell ( PEMFC ), alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC), solid oxide fuel...SOFC and PAFC belong to high temperature fuel cell, which can be applied in stationary power generation. PEMFC and AFC belong to low temperature fuel...function of the polymer electrolyte is to serve as electrolyte to transport ions between electrodes. PEMFC uses a polymer as electrolyte and works

  20. Exploring Alkaline Stable Organic Cations for Polymer Hydroxide Exchange Membranes

    Science.gov (United States)

    2015-04-29

    1   1.1.2   Proton exchange membrane fuel cells ( PEMFCs ) ......................... 3   1.1.3   Alkaline fuel cells (AFCs...160   xi LIST OF FIGURES Figure 1.1:   Schematic diagram of a PEMFC ...according to the type of electrolyte they use. Nowadays, there are six major types of fuel cells: proton-exchange membrane fuel cells ( PEMFCs ), hydroxide

  1. 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.)

  2. Spectroscopic characterization of manganese-doped alkaline earth

    Indian Academy of Sciences (India)

    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.

  3. 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...

  4. Positron collisions with helium and alkaline earth-like atoms

    International Nuclear Information System (INIS)

    Campbell, C.P.

    1998-09-01

    This doctoral thesis is subdivided into: 1. Theory of positron collisions with helium and alkaline earth-like atoms, 2. Positron collisions with helium, magnesium, calcium, zinc, 3. Intercomparison of positron scattering by all those elements. The appendix of this work gives details of the numerical calculations and expands on the wavefunctions used

  5. Structural variations in layered alkaline earth metal cyclohexyl ...

    Indian Academy of Sciences (India)

    Administrator

    because of the entrance of the guest molecules between the layers, there will be a change in the interlayer distance (Alberti 1978). Although M(IV) organo-phos- phonates are well documented, the chemistry of M(II) organophosphonates especially the alkaline earth metal organophosphonates has been explored marginally ...

  6. 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...

  7. Effects of Mixed Alkaline Earth Oxides in Potash Silicate Glass ...

    African Journals Online (AJOL)

    The aim of this work is to investigate the effects of mixed alkaline earth oxide in potash silicate glasses with regards to their physical properties. More recently; there has been an increase in the demand for light weight glasses which retains their physical and chemical properties for both domestic and industrial applications.

  8. Alkaline-earth metal phenylphosphonates and their intercalation chemistry

    Czech Academy of Sciences Publication Activity Database

    Melánová, Klára; Beneš, L.; Svoboda, J.; Zima, Vítězslav; Pospíšil, M.; Kovář, P.

    2018-01-01

    Roč. 47, č. 9 (2018), s. 2867-2880 ISSN 1477-9226 R&D Projects: GA ČR(CZ) GA17-10639S Institutional support: RVO:61389013 Keywords : intercalation * layered compounds * alkaline-earth metal phenylphosphonates Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 4.029, year: 2016

  9. Calculation of the electronic structure and contact hyperfine parameters of interstitial hydrogen in alkaline - earth fluorides

    International Nuclear Information System (INIS)

    Oliveira, L.E.M.C. de.

    1976-01-01

    The electronic structure of the interstitial hydrogen atom in alkaline-earth fluorides has been studied using the self-consistent-field multiple-scattering Xα method. In the calculations a cluster constituted by the hydrogen atom and its first anion and cation neighbors has been used. The contact parameters with the proton and the fluorine nuclei have been evaluated. The agreement obtained with the experimental results is in general good and indicates that this method is also appropriate to study defects in ionic crystals. (author) [pt

  10. Temperature Dependence of Mineral Solubility in Water. Part 2. Alkaline and Alkaline Earth Bromides

    Science.gov (United States)

    Krumgalz, B. S.

    2018-03-01

    Databases of alkaline and alkaline earth bromide solubilities in water at various temperatures were created using experimental data from publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed bromide minerals have been calculated at various temperature intervals and also represented by polynomial expressions.

  11. Melt cationic and anionic composition effect on titanium group metal corrosion in halogenides of alkali earths

    International Nuclear Information System (INIS)

    Tkhaj, V.; Kovalik, O.Yu.; Dikunov, Yu.G.; P'yankova, S.P.

    1997-01-01

    A study was made on interaction of titanium group metals with melts of chlorides and chloride-fluorides of alkaline earth metals and magnesium. It was revealed that the rate of metal corrosion increased from BaCl 2 2 2 2 in chloride series. It is explained by amplification of oxidation activity of salt cation in the series: Ba 2+ 2+ 2+ 2+ . It was also determined that corrosion rate of titanium exceeded the one of zirconium and hafnium, became reducing power of titanium was the highest in the given group

  12. Thermochemical and thermophysical properties of alkaline-earth perovskites

    International Nuclear Information System (INIS)

    Yamanaka, Shinsuke; Kurosaki, Ken; Maekawa, Takuji; Matsuda, Tetsushi; Kobayashi, Shin-ichi; Uno, Masayoshi

    2005-01-01

    In order to contribute to safety evaluation of high burnup oxide fuels, we studied the thermochemical and thermophysical properties of alkaline-earth perovskites known as oxide inclusions. Polycrystalline samples of alkaline-earth perovskites, BaUO 3 , BaZrO 3 , BaCeO 3 , BaMoO 3 , SrTiO 3 , SrZrO 3 , SrCeO 3 , SrMoO 3 , SrHfO 3 and SrRuO 3 , were prepared and the thermal expansion coefficient, melting temperature, elastic moduli, Debye temperature, microhardness, heat capacity, and thermal conductivity were measured. The relationship between some physical properties was studied

  13. Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

    Indian Academy of Sciences (India)

    Moisture-insensitive metal carboxylates that are mostly liquids at room temperature have been first applied to ... alkaline-earth ion, or possibly even a rare-earth ion and alkali metal ... sion spectra of the powders were recorded on a fluorescent.

  14. Defect structure of cubic solid solutions of alkaline earth and rare earth fluorides

    NARCIS (Netherlands)

    DenHartog, HW

    1996-01-01

    In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the

  15. Ab initio study of the adducts of carbon monoxide with alkaline cations

    Science.gov (United States)

    Ferrari, A. M.; Ugliengo, P.; Garrone, E.

    1996-09-01

    The interaction between CO (either via the C or the O end) and the alkaline cations (Li+, Na+, K+, Rb+, and Cs+) has been studied by means of six ab initio methods, featuring the classical Hartree-Fock, the second order Møller-Plesset treatment of electron correlation, one local density functional and two gradient-corrected methods as well as a quadratic configuration interaction inclusive of single and double substitutions with a noniterative triples contribution to the energy. Basis sets adopted for CO, Li+, Na+, and K+ and the corresponding adducts are of triple-ζ valence quality augmented with a double set of polarization functions (d on C and O; p on the cations). For Rb+ and Cs+, Hay-Wadt effective core potential basis sets have been adopted. Calculated features are the binding energy, the frequency and intensity of the CO stretch, the bending mode, the cation-carbon (or oxygen) stretch, and the equilibrium geometry. Gradient-corrected density functional methods yield results nearly as good as the most expensive correlated method based on configurations interaction. A number of correlations are established among the observables. The role of electrostatics in the interaction is analyzed both by studying the molecular electrostatic potential of CO and by replacing the cation with a proton in the same position. Binding through the C end is invariably preferred, though, with increasing size of the cation, binding through the O end become progressively less unfavored. Experimental data concerning alkaline-cation substituted zeolites are compared with computational results, and an overall agreement is observed.

  16. Cation colloidal particles in alkaline-earth halides

    Energy Technology Data Exchange (ETDEWEB)

    Alcala, R; Orera, V M [Zaragoza Univ. (Spain). Facultad da Ciencias

    1976-01-01

    The formation of calcium, strontium and barium colloids both in heavily electron irradiated samples and in additively colored crystals of CaF/sub 2/, SrF/sub 2/ and BaF/sub 2/ has been investigated. Detailed data on the temperature dependence of the efficiency of colloid formation by irradiation have been obained. The growth of metallic particles in additively colored samples containing F and M centers has been studied for different color center concentrations and annealing temperatures. The optical absorption bands due to metallic colloids have been calculated using the theory of Mie. To take account of the pressure exerted by the matrix on the metallic particles several corrections to the optical constants of the metals have been introduced. A good agreement between theoretical calculations and experimental results has been obtained. The evolution of colloids along several thermal annealing experiments has also been investigated. A diffusion-limited model has been used which accounts for the dependence of the colloid radii with the annealing time.

  17. Cation Substitution in Earth-Abundant Kesterite Photovoltaic Materials.

    Science.gov (United States)

    Li, Jianjun; Wang, Dongxiao; Li, Xiuling; Zeng, Yu; Zhang, Yi

    2018-04-01

    As a promising candidate for low-cost and environmentally friendly thin-film photovoltaics, the emerging kesterite-based Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells have experienced rapid advances over the past decade. However, the record efficiency of CZTSSe solar cells (12.6%) is still significantly lower than those of its predecessors Cu(In,Ga)Se 2 (CIGS) and CdTe thin-film solar cells. This record has remained for several years. The main obstacle for this stagnation is unanimously attributed to the large open-circuit voltage ( V OC ) deficit. In addition to cation disordering and the associated band tailing, unpassivated interface defects and undesirable energy band alignment are two other culprits that account for the large V OC deficit in kesterite solar cells. To capture the great potential of kesterite solar cells as prospective earth-abundant photovoltaic technology, current research focuses on cation substitution for CZTSSe-based materials. The aim here is to examine recent efforts to overcome the V OC limit of kesterite solar cells by cation substitution and to further illuminate several emerging prospective strategies, including: i) suppressing the cation disordering by distant isoelectronic cation substitution, ii) optimizing the junction band alignment and constructing a graded bandgap in absorber, and iii) engineering the interface defects and enhancing the junction band bending.

  18. Blue photoluminescence in Ti-doped alkaline-earth stannates

    International Nuclear Information System (INIS)

    Yamashita, Takahiro; Ueda, Kazushige

    2007-01-01

    Blue photoluminescence properties of Ti-doped alkaline-earth stannates, A 2 (Sn 1- x Ti x )O 4 (A=Ca, Sr, Ba) (x=0.005-0.15), were examined at room temperature. These stannates showed intense broad emission bands peaking at 445 nm for Ca 2 SnO 4 , at 410 nm for Sr 2 SnO 4 , and at 425 nm for Ba 2 SnO 4 under UV excitation. Emission intensities were relatively insensitive to Ti concentration and no sharp concentration quenching was observed. Mixing alkaline-earth ions in the crystal structures did not increase the emission intensities in the A 2 (Sn 1- x Ti x )O 4 system. The excitation spectra of these stannates exhibited broad bands just below the fundamental absorption edges, implying that luminescence centers do not consist of the component elements in the host materials. It was suggested that the isolated TiO 6 complexes are possible luminescence centers in these materials, as previously proposed in other Ti-doped stannates such as Mg 2 SnO 4 and Y 2 Sn 2 O 7 . - Graphical abstract: Blue photoluminescence properties of Ti-doped alkaline-earth stannates, A 2 (Sn 1- x Ti x )O 4 (A=Ca, Sr, Ba) (x=0.005-0.15), were examined at room temperature. These stannates showed intense broad emission bands peaking at 445 nm for Ca 2 SnO 4 , at 410 nm for Sr 2 SnO 4 , and at 425 nm for Ba 2 SnO 4 under UV excitation

  19. Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

    Science.gov (United States)

    Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

    2018-04-01

    As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

  20. Crystal and defect chemistry influences on band gap trends in alkaline earth perovskites

    International Nuclear Information System (INIS)

    Lee, Soonil; Woodford, William H.; Randall, Clive A.

    2008-01-01

    A number of perovskites with A-site alkaline earth chemistries being Ca, Sr, and Ba, and tetravalent cations including Ce, Zr, and Ti are measured for optical band gap and found to vary systematically with tolerance factor and lattice volume within limits defined by the chemistry of the octahedral site. This paper also focuses on the BaTiO 3 system, considering equilibrated nonstoichiometries, and determines the changes in band gap with respect to Ba/Ti ratios. It was found that the optical band gap changes in the solid solution regime and is invariant in the second phase regions, as would be expected. In the cases of Ba/Ti 1.0 stoichiometries, there is a distinct Urbach tail and the trend with lattice volume no longer holds. It is inferred that the V Ti q prime-2V O partial Schottky complex controls the band gap trend with Ba-rich nonstoichiometries

  1. Reaction cross section calculation of some alkaline earth elements

    Science.gov (United States)

    Tel, Eyyup; Kavun, Yusuf; Sarpün, Ismail Hakki

    2017-09-01

    Reaction cross section knowledge is crucial to application nuclear physics such as medical imaging, radiation shielding and material evaluations. Nuclear reaction codes can be used if the experimental data are unavailable or are improbably to be produced because of the experimental trouble. In this study, there action cross sections of some target alkaline earth elements have been calculated by using pre-equilibrium and equilibrium nuclear reaction models for nucleon induced reactions. While these calculations, the Hybrid Model, the Geometry Dependent Hybrid Model, the Full Exciton Model, the Cascade Exciton Model for pre-equilibrium reactions and the Weisskopf-Ewing Model for equilibrium reactions have been used. The calculated cross sections have been discussed and compared with the experimental data taken from Experimental Nuclear Reaction Data library.

  2. Reaction cross section calculation of some alkaline earth elements

    Directory of Open Access Journals (Sweden)

    Tel Eyyup

    2017-01-01

    Full Text Available Reaction cross section knowledge is crucial to application nuclear physics such as medical imaging, radiation shielding and material evaluations. Nuclear reaction codes can be used if the experimental data are unavailable or are improbably to be produced because of the experimental trouble. In this study, there action cross sections of some target alkaline earth elements have been calculated by using pre-equilibrium and equilibrium nuclear reaction models for nucleon induced reactions. While these calculations, the Hybrid Model, the Geometry Dependent Hybrid Model, the Full Exciton Model, the Cascade Exciton Model for pre-equilibrium reactions and the Weisskopf-Ewing Model for equilibrium reactions have been used. The calculated cross sections have been discussed and compared with the experimental data taken from Experimental Nuclear Reaction Data library.

  3. Many-body physics with alkaline-earth Rydberg lattices

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, R; Nath, R; Pohl, T [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany); Millen, J; Jones, M P A, E-mail: rick@pks.mpg.de [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

    2011-09-28

    We explore the prospects for confining alkaline-earth Rydberg atoms in an optical lattice via optical dressing of the secondary core-valence electron. Focussing on the particular case of strontium, we identify experimentally accessible magic wavelengths for simultaneous trapping of ground and Rydberg states. A detailed analysis of relevant loss mechanisms shows that the overall lifetime of such a system is limited only by the spontaneous decay of the Rydberg state, and is not significantly affected by photoionization or autoionization. The van der Waals C{sub 6} coefficients for the Sr(5sns {sup 1}S{sub 0}) Rydberg series are calculated, and we find that the interactions are attractive. Finally we show that the combination of magic-wavelength lattices and attractive interactions could be exploited to generate many-body Greenberger-Horne-Zeilinger states.

  4. The effect of alkaline cations on the Intercalation of Carbon Dioxide in Sepiolite Minerals: a Molecular Dynamics Investigation.

    Science.gov (United States)

    Tavanti, Francesco; Muniz-Miranda, Francesco; Pedone, Alfonso

    2018-03-01

    The ability of the sepiolite mineral to intercalate CO2 molecules inside its channels in the presence of different alkaline cations (K+, Na+ and Li+) has been studied by classical Molecular Dynamics simulations. Starting from an alkaline-free sepiolite crystalline model we built three models with stoichiometry Mg320Si440Al40O1200(OH)160X+40•480H2O. On these models, we gradually replaced the water molecules present in the channels with carbon dioxide and determined the energy of this exchange reaction as well as the structural organization and dynamics of carbon dioxide in the channels. The adsorption energy shows that the Li-containing sepiolite mineral retains more carbon dioxide with respect to those with sodium and potassium cations in the channels. Moreover, the ordered patterns of CO2 molecules observed in the alkaline-free sepiolite mineral are in part destabilized by the presence of cations decreasing the adsorption capacity of this clay mineral.

  5. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Science.gov (United States)

    2010-07-01

    ... metalloid oxyanions. 721.4668 Section 721.4668 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... 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 under...

  6. Daily intakes of alkaline earth metals in Japanese males

    International Nuclear Information System (INIS)

    Shiraishi, Kunio; Yamamoto, Masayoshi; Ueno, Kaoru

    1994-01-01

    Diet samples were collected for two duplicate portion studies and one market basket study. 226 Ra in the diet samples was determined by alpha spectrometry and daily intake was estimated as 23 mBq (0.62 pCi) per person. Other alkaline earth metals were determined by inductively coupled plasma atomic-emission spectrometry. Average mineral intakes of calcium, magnesium, strontium, and barium were 0.55 g, 0.21 g, 2.3 mg, and 0.39 mg, respectively. Element ratios magnesium:calcium 0.38, strontium:calcium 4.2 x 10 -3 barium:calcium 7.1 X 10 -4 , and Ra:calcium 1.1 x 10 -12 were found in the diet; these compared with element ratios in Japanese vertebrae of magnesium:calcium 0.011, strontium:calcium 3.1 x 10 -4 , barium:calcium 2.7 x 10 -5 , and radium:calcium 2.6 x 10 -14 . Observed ratios, defined as the element ratio in bone divided by the respective element intake ratio in Japanese males, were as follows: 226 Ra 0.02, magnesium 0.03, strontium 0.07, and barium 0.04

  7. Naphthenic acid removal from HVGO by alkaline earth metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ding, L.; Rahimi, P.; Hawkins, R.; Bhatt, S.; Shi, Y. [National Centre for Upgrading Technology, Devon, AB (Canada); Natural Resources Canada, Devon, AB (Canada). CanmetENERGY

    2009-07-01

    This poster highlighted a study that investigated naphthenic acid removal from bitumen-derived heavy vacuum gas oil (HVGO) by thermal cracking and catalytic decarboxylation over alkaline earth-metal oxides and ZnO catalysts in a batch reactor and a continuous fixed-bed reactor. X-ray diffraction (XRD), thermogravimetric-differential thermal analysis (TG-DTA) temperature-programmed desorption (TPD) of carbon dioxide (CO{sub 2}-TPD), and scanning electron microscopy were used to characterize the fresh and spent catalysts. With MgO and ZnO, naphthenic acid removal proceeded via catalytic decarboxylation. No crystalline phase changes were observed after reaction. With CaO, multiple pathways such as catalytic decarboxylation, neutralization, and thermal cracking were responsible for naphthenic acid conversion. The spent catalysts contained Ca(OH){sub 2} and CaCO{sub 3}. With BaO, naphthenic acid conversion occurred through neutralization. All BaO was converted to Ba(OH){sub 2} during the reaction. tabs., figs.

  8. Effect of rare earth cations on activity of type Y zeolites in ethylene transformations

    International Nuclear Information System (INIS)

    Amezhnova, G.N.; Zhavoronkov, M.N.; Dorogochinskij, A.Z.; Proskurin, A.L.; Shmailova, V.I.

    1984-01-01

    The ethylene transformations on type Y rare earth zeolites with high degrees of sodium exchange are studied. It is shown that rare earth cations increase zeolites activity with growth of electronoacceptor capacity. The ethylene oligomerization occurs on polyvalent cations while subsequent oligomer transformations - on hydroxyl groups of zeolites

  9. On the capacity to the complexing of alkaline earth metal and magnesium chromates

    International Nuclear Information System (INIS)

    Orekhov, O.L.

    1978-01-01

    Considered is the capacity to the complexing of magnesium chromates and alkaline earth metal chromates with ammonium chromates in aqueous solutions. It has been established that the complexing of alkaline earth metal and magnesium chromates is effected by a nature of initial salts as well as their solubilities and the presence of crystallization water. Capacity of magnesium ions and alkaline rare earth metals to the complexing decreases in a series of Mg-Ca-Sr-Ba. Ca complexes exceed magnesium derivatives in respect of stability

  10. When VSEPR fails: experimental and theoretical investigations of the behavior of alkaline-earth-metal acetylides.

    Science.gov (United States)

    Guino-o, Marites A; Alexander, Jacob S; McKee, Michael L; Hope, Håkon; Englich, Ulrich B; Ruhlandt-Senge, Karin

    2009-11-09

    The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry.

  11. The electronic structure of rare-earth luminescent centre in alkaline-earth sulphides

    International Nuclear Information System (INIS)

    Zheng Qingqi; Pan Wei; Huang Maichun; He Xiaoguang

    1988-09-01

    The cluster method is used to investigate the electronic structure of rare-earth Eu 2+ and Ce 3+ doped SrS and CaS alkaline-earth sulphides in the local density theory regime. The ground state is obtained self-consistently by the DV-X α method, while the transition state theory is used to calculate the excited states. The energy difference between ground state and excited state is 2.95 eV (420 nm) for CaS:Eu is in good agreement with the experimental data of 430 nm for the absorption peak in SrS:Cu. The composition of ground state and excited state is also calculated which can give information about the EL excitation mechanism. (author). 7 refs, 4 figs, 3 tabs

  12. Synthesis and structure of alkaline earth and rare earth metal doped C70

    International Nuclear Information System (INIS)

    Takenobu, Taishi; Iwasa, Yoshihiro; Ito, Takayoshi; Mitani, Tadaoki

    2001-01-01

    We have investigated the structure sequence of alkaline earth (A=Ba, Sr) and rare earth metal (R=Eu) doped C 70 binary system. X-ray diffraction measurements revealed that there exist at least four stable phases at x=3, 4, 6, and 9 in A x C 70 and two stable phases at x=3, and 9 in R x C 70 . Among them, structural models are presented for Ba 4 C 70 , Sr 3 C 70 , and Eu 3 C 70 . Ba 4 C 70 takes an analogous structure to orthorhombic Ba 4 C 60 . Sr 3 C 70 and Eu 3 C 70 have monoclinic cell and their diffraction patterns are quite similar to that of Sm 3 C 70 , which involves a unique C 70 -metal-C 70 dimer structure. Preliminary results of Raman spectroscopy and magnetization measurement suggest the highly reduction state for A 9 C 70 and ferromagnetic interaction for Eu x C 70

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

    International Nuclear Information System (INIS)

    Menes, F.

    1969-01-01

    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 CaBr 2 - (CaBr 2 + 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 48 Ca 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, MgBr 2 - CeBr 3 . 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) [fr

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

    Indian Academy of Sciences (India)

    computed the velocity autocorrelation function (VACF), its memory function and ... Since alkaline-earth metals are simple like metals, the main difficulty in the calcu- lation of ..... recall that the conventional binding energy can be written [23] as.

  15. Desorption of acetone from alkaline-earth exchanged Y zeolite after propane selective oxidation

    NARCIS (Netherlands)

    Xu, J.; Mojet, Barbara; van Ommen, J.G.; Lefferts, Leonardus

    2004-01-01

    The desorption of products from a series of alkaline-earth exchanged Y zeolites after room-temperature propane selective oxidation was investigated by in situ infrared and mass spectroscopy. The intermediate product, isopropylhydroperoxide (IHP), did not desorb during

  16. The application of extraction chromatography for analysis of alkali and alkaline earth uranates

    International Nuclear Information System (INIS)

    Tomazic, B.; Cukovic, M.

    1978-01-01

    A method for rapid analysis of alkali and alkaline earth uranates is proposed. The method is based on the use of an HDEHP extraction chromatographic column, which makes possible quantitative separations of alkaline earth ions from macroamounts of uranium(VI). Composition of alkaline earth uranates, based on regression analysis, are presented. The results, which show that under the given experimental conditions alkaline earth triuranates precipitate, are in good agreement with previous data from same laboratory. In addition the HDEHP extraction chromatographic column can be suggested as a tool for separation of representative fission products from irradiated uranium for the purpose of determination of the burn-up factor of nuclear reactor materials. (T.G.)

  17. 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)

    Quintas, A.; Caurant, D.; Majerus, O.; Charpentier, T.; Dussossoy, J.L.

    2008-01-01

    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 (R 2+ = Sr 2+ , Ba 2+ ) 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 R 2+ cations on both glass structure and melt crystallization tendency during cooling, two glass series were prepared by replacing either Na + or Ca 2+ cations in the simplified glass by respectively (Li + , K + , Rb + , Cs + ) or (Mg 2+ , Sr 2+ , Ba 2+ ) cations. From these substitutions, it was established that alkali ions are preferentially involved in the charge compensation of (AlO 4 ) - 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)

  18. Study of alkaline-earth element complexes in anhydrous acetic acid

    International Nuclear Information System (INIS)

    Petit, N.

    1968-10-01

    We have studied the complexes of alkaline-earth elements in anhydrous acetic acid. Using glass-electrode potentiometry we have studied the titration of alkaline earth acetates with perchloric acid which is the strongest acid in anhydrous acetic acid. These titrations have shown that the basic strength of these acetates increases as follows: Mg 4 ); the mixed acetate-acid sulfate complex of barium: Ba (OAc)(HSO 4 ); the mixed acetate-chloride of barium: Ba (OAc)(Cl). (author) [fr

  19. A Kirkwood-Buff derived force field for alkaline earth halide salts

    Science.gov (United States)

    Naleem, Nawavi; Bentenitis, Nikolaos; Smith, Paul E.

    2018-06-01

    The activity and function of many macromolecules in cellular environments are coupled with the binding of divalent ions such as calcium or magnesium. In principle, computer simulations can be used to understand the molecular level aspects of how many important macromolecules interact with ions. However, most of the force fields currently available often fail to accurately reproduce the properties of divalent ions in aqueous environments. Here we develop classical non-polarizable force fields for the aqueous alkaline earth metal halides (MX2), where M = Mg2+, Ca2+, Sr2+, Ba2+ and X = Cl-, Br-, I-, which can be used in bimolecular simulations and which are compatible with the Simple Point Charge/Extended (SPC/E) water model. The force field parameters are specifically developed to reproduce the experimental Kirkwood-Buff integrals for aqueous solutions and thereby the experimental activity derivatives, partial molar volumes, and excess coordination numbers. This ensures that a reasonable balance between ion-ion, ion-water, and water-water distributions is obtained. However, this requires a scaling of the cation to water oxygen interaction strength in order to accurately reproduce the integrals. The scaling factors developed for chloride salts are successfully transferable to the bromide and iodide salts. Use of these new models leads to reasonable diffusion constants and dielectric decrements. However, the performance of the models decreases with increasing salt concentration (>4m), and simulations of the pure crystals exhibited unstable behavior.

  20. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hackbarth, Liisa

    2015-11-24

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H{sub 2}O){sub 5}][B(CN){sub 4}]{sub 3}.0.5 H{sub 2}O, where LRE{sup 3+} is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3} and the [HRE(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.3 H{sub 2}O, where HRE{sup 3+} is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical

  1. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    International Nuclear Information System (INIS)

    Hackbarth, Liisa

    2015-01-01

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H_2O)_5][B(CN)_4]_3.0.5 H_2O, where LRE"3"+ is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H_2O)_7][B(CN)_4]_3 and the [HRE(H_2O)_8][B(CN)_4]_3.3 H_2O, where HRE"3"+ is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical measurements indicate that the tetracyanidoborates with rare earth metal cations

  2. Photoionization of subvalence p-subshell in alkali and alkaline-earth atoms

    International Nuclear Information System (INIS)

    Yagishita, A.; Hayaishi, T.; Itoh, Y.

    1986-11-01

    Photoionization of alkali and alkaline-earth atoms has been investigated by means of a time-of-flight mass spectrometer combined with monochromatised synchrotron radiation and an atomic beam, in the wavelength region of 350 - 750 A. For alkaline-earth atoms, it has been made clear that a two-step autoionization following an innershell excitation plays an important role for doubly charged ions. For alkali atoms, relative photoionization cross sections have been measured for the first time. Moreover, a tentative assignment of spectral lines for Rb and Cs in the complex spectral region has been attemped based on the photoionization data. (author)

  3. Separation of alkali and alkaline earth metals by polyethers using extraction chromatography

    International Nuclear Information System (INIS)

    Smulek, W.; Lada, W.A.

    1979-01-01

    The separation of alkali and alkaline earth metals by means of an acyclic polyether, 1,13-bis(8-chinolinyl)-1, 4, 7, 10, 13-pentaoxatridecane (CPOD), and cyclic polyethers, benzo-15-crown-5 (BC), dibenzo-18-crown-6 (DBC) and dicyclohexyl-18-crown-6 (DCHC), using extraction chromatography has been studied. The alkali metals can be effectively separated using SCN - as the accompanying ion. For alkaline earth metals, the best results were obtained with ClO 4 - ions. Different elution sequences for these groups were observed using chloroform and/meen=/ sitylene as diluents for the polyethers. (author)

  4. Electric dipole moments and chemical bonding of diatomic alkali-alkaline earth molecules.

    Science.gov (United States)

    Pototschnig, Johann V; Hauser, Andreas W; Ernst, Wolfgang E

    2016-02-17

    We investigate the properties of alkali-alkaline earth diatomic molecules in the lowest Σ(+) states of the doublet and quartet multiplicity by ab initio calculations. In all sixteen cases studied, the permanent electric dipole moment points in opposite directions for the two spin states. This peculiarity can be explained by molecular orbital theory. We further discuss dissociation energies and bond distances. We analyze trends and provide an empirically motivated model for the prediction of the permanent electric dipole moment for combinations of alkali and alkaline earth atoms not studied in this work.

  5. 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)

    Kelkar, Anoop; Prakash, Amrit; Afzal, Mohd.; Panakkal, J.P.

    2009-02-01

    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 UO 2 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), Na 2 SO 4 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 Fe 3+ , Cu 2+ , Ni 2+ , Co 2+ , Cd 2+ , Mn 2+ , Li + , Na + , K + , Mg 2+ , Ca 2+ and Sr 2+ 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 UO 2 sample by solvent extraction with 30% TBP - TOPO/CCl 4 . 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 UO 2 . (author)

  6. The alkali and alkaline earth metal doped ZnO nanotubes: DFT studies

    International Nuclear Information System (INIS)

    Peyghan, Ali Ahmadi; Noei, Maziar

    2014-01-01

    Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO–LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ∼1.11–1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface

  7. Use of polysulfides of alkali and alkaline-earth metals to obtain highly dispersed sulfur

    International Nuclear Information System (INIS)

    Massalimov, I.A.; Vikhareva, I.N.; Kireeva, M.S.

    2008-01-01

    Possibilities of obtaining polysulfides of alkali and alkaline earth metals (M is Na, K, Ca, Sr, Ba) in aqueous solutions were considered. The composition of the polysulfides and their concentration in solutions were found. The efficiencies of application of highly dispersed sulfur, produced from calcium polysulfide, and colloid sulfur as a fungicide were compared [ru

  8. 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 - others:AV ČR(CZ) M200501202 Program:M Institutional support: RVO:61389013 Keywords : coordination polymers * phosphonates * alkaline-earth Subject RIV: CA - Inorganic Chemistry Impact factor: 4.097, year: 2013

  9. A Kinetic Insight into the Activation of n -Octane with Alkaline-Earth ...

    African Journals Online (AJOL)

    Alkaline-earth metal hydroxyapatites are prepared by the co-precipitation method and characterized using XRD, ICP,NH3-TPD, SEM-EDX, TEM and N2 physisorption analysis. The metal present in the hydroxyapatite influences the acidity of the catalyst. Oxidative dehydrogenation reactions carried out in a continuous flow ...

  10. Vibrational spectra of double rare earth alkaline metal metaphosphates

    International Nuclear Information System (INIS)

    Madij, V.A.; Krasilov, Yu.I.; Kizel', V.A.; Denisov, Yu.V.; Chudinova, N.N.; Vinogradova, N.V.

    1978-01-01

    Joint analysis of the Raman and infrared absorption spectra, as well as X-ray structural data for binary metaphosphates, suggest a cyclic structure of the anion in RbEu(PO 3 ) 4 and a chain structure of the anions in HEu(PO 3 ) 4 and LiEu(PO 3 ) 4 . Spectroscopic criteria are proposed for distinguishing between cyclic and chain structures in binary metaphosphates of rare earth elements and alkali metals

  11. Interactions of nucleobases with alkali earth metal cations--electrospray ionization mass spectrometric study.

    Science.gov (United States)

    Frańska, Magdalena

    2007-01-01

    Interactions of nucleobases with alkali earth metal cations have been studied by electrospray ionization mass spectrometry (ESI-MS). Nucleobases containing at least one oxygen atom form stable complexes with alkali earth metal cations. This phenomenon can be explained on the grounds of the well known theory of hard and soft acids and bases. Uracil and thymine make complexes only when in their deprotonoted forms. The cations of great radii (Sr(2+), Ba(2+)) are more prone to form complexes of stoichiometry 1:1 with uracil and thymine than the cations of small radii (Mg(2+), Ca(2+)). On the other hand, Mg(2+) forms complexes of stoichiometry 2:1 and 3:2 with uracil and thymine. Gas-phase stabilities of the 1:1 complexes are higher for the cations of small radii, in contrast to the solution stabilities. For cytosine and 9- methylhypoxantine the 1:1 complexes of their deprotonated forms are observed at higher cone voltage as a result of HCl molecule loss from the complexes containing the counter ion (Cl(-)). In solution, more stable complexes are formed with metal cations of low radii. Gas-phase stability of the complexes formed by deprotonated 9- methyl-hypoxantine increases with increasing metal cation radius.

  12. 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.

  13. Structural and Dynamical Properties of Alkaline Earth Metal Halides in Supercritical Water: Effect of Ion Size and Concentration.

    Science.gov (United States)

    Keshri, Sonanki; Tembe, B L

    2017-11-22

    Constant temperature-constant pressure molecular dynamics simulations have been performed for aqueous alkaline earth metal chloride [M 2+ -Cl - (M = Mg, Ca, Sr, and Ba)] solutions over a wide range of concentrations (0.27-5.55 m) in supercritical (SC) and ambient conditions to investigate their structural and dynamical properties. A strong influence of the salt concentration is observed on the ion-ion pair correlation functions in both ambient and SC conditions. In SC conditions, significant clustering is observed in the 0.27 m solution, whereas the reverse situation is observed at room temperature and this is also supported by the residence times of the clusters. The concentration and ion size (cation size) seem to have opposite effects on the average number of hydrogen bonds. The simulation results show that the self-diffusion coefficients of water, cations, and the chloride ion increase with increasing temperature, whereas they decrease with increasing salt concentration. The cluster size distribution shows a strong density dependence in both ambient and SC conditions. In SC conditions, cluster sizes display a near-Gaussian distribution, whereas the distribution decays monotonically in ambient conditions.

  14. 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.

  15. Influence of alkali and alkaline earth elements on the uptake of radionuclides by Pleurototus eryngii fruit bodies

    International Nuclear Information System (INIS)

    Guillén, J.; Baeza, A.; Salas, A.

    2012-01-01

    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 cæsium) and alkaline earth (calcium and strontium) elements. The transfer of 134 Cs, 85 Sr, and 60 Co (added to the cultures) and of natural 210 Pb was analysed by increasing the content of each stable element considered. A significant, but nonlinear, enhancement of stable cæsium and 134 Cs was observed with increasing content of stable cæsium in the substrate/mycelium. The transfer of 85 Sr decreased with the addition of each stable cation, whereas the 60 Co and 210 Pb transfers were unaffected. - Highlights: ► The addition of stable potassium did not affect the uptake of radiocaesium. ► The addition of stable caesium increased the stable caesium and 134 Cs content in the fruiting bodies of Pleurotus eryngii. ► The addition of calcium reduced the content of calcium and 85 Sr in the fruiting bodies. ► These countermeasures did not work properly in the case of 60 Co and 210 Pb, no effect was observed.

  16. 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.

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

    DEFF Research Database (Denmark)

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

    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 comp......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....... 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 stress...

  18. Calculated solubility isotherm of a system of alkaline earth sulfates and hydroxides in water

    International Nuclear Information System (INIS)

    MOshinskii, A.S.; TIkomirova, K.A.

    1986-01-01

    Tis paper examines the calculation of the isothermal solubility diagram of a system of alkaline earth sulfates and hydroxides in water which makes it possible to substantiate, to a considerable extent, the natural physicochemical mineralization of natural waters, in particular water from geochemical sources. The present paper investigates the solubility of the equilibrium solid phases of a system of alkaline earth sulfates and hydroxides in water. A projection is shown of the composition prism of the quinary reciprocal system with demarcation of the crystallization areas of each sulfate and hydroxide of the component subsystems. The computational formulas for calculating solubility were derived from the solubility product principle, with allowance for ion activity coefficients in saturated hydroxide solutions

  19. IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

    Science.gov (United States)

    Vanderdeelen, Jan

    2012-06-01

    The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO3 types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO3. H2O), the hexahydrate ikaite (CaCO3.6H2O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.

  20. IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

    International Nuclear Information System (INIS)

    De Visscher, Alex; Vanderdeelen, Jan

    2012-01-01

    The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO 3 types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO 3 · H 2 O), the hexahydrate ikaite (CaCO 3 ·6H 2 O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.

  1. IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

    Energy Technology Data Exchange (ETDEWEB)

    De Visscher, Alex; Vanderdeelen, Jan [Department of Chemical and Petroleum Engineering, and Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, Alberta, T2N 1N4 (Canada); Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent (Belgium)

    2012-06-15

    The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO{sub 3} types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO{sub 3}{center_dot} H{sub 2}O), the hexahydrate ikaite (CaCO{sub 3}{center_dot}6H{sub 2}O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.

  2. Effect of the kind of alkaline and rare earth ions on the structure of a glass rich in earth

    International Nuclear Information System (INIS)

    Quintas, Arnaud; Caurant, Daniel; Majerus, Odile; Lenoir, Marion; Dussossoy, Jean-Luc; Charpentier, Thibault; Neuville, Daniel R.; Gervais, C.

    2006-01-01

    In the framework of a structural study of a nuclear wastes containment glass of type alumino borosilicate and rich in rare earths, the influence of the kind of alkaline or rare earth ions is analyzed. For that, two glasses series have been prepared in which the Na + ion (respectively Ca 2+ ions) present in the standard composition is totally substituted by another alkaline ion Li + , K + , Rb + or Cs + (respectively another rare earth ion Mg 2+ , Sr 2+ or Ba 2+ ). These glasses, analyzed by optical absorption, Raman and 27 Al or 11 B NMR spectroscopies have revealed the strong impact of the kind of the modifying ion as well as the structure of the vitreous lattice (variation of the ratio BO 3 /BO 4 and local variations of the polymerization degree) than the local surroundings of the rare earth (decrease of the covalency degree of the bond Nd-O with the increase of the field force of the modifying ion). (O.M.)

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

    International Nuclear Information System (INIS)

    Mitroy, J.; Bromley, M.W.J.

    2004-01-01

    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

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

    International Nuclear Information System (INIS)

    Jiang Jun; Cheng Yongjun; 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. (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, S. Sreehari, E-mail: sreeharisastry@yahoo.com [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Rao, B. Rupa Venkateswara [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Department of Physics, V.R. Siddhartha Engineering College, Vijayawada 52007 (India)

    2014-02-01

    In this paper spectroscopic investigation of Cu{sup 2+} 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 Cu{sup 2+} state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu{sup 2+} 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.

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

    International Nuclear Information System (INIS)

    Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

    2014-01-01

    In this paper spectroscopic investigation of Cu 2+ 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 Cu 2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu 2+ 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

  7. Adsorption of alkali and alkaline-earth metal atoms on stanene: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Kadioglu, Yelda; Ersan, Fatih [Department of Physics, Adnan Menderes University, 09100 Aydın (Turkey); Gökoğlu, Gökhan [Department of Physics, Karabük University, 78050 Karabük (Turkey); Aktürk, Olcay Üzengi [Department of Electrical & Electronics Engineering, Adnan Menderes University, 09100 Aydın (Turkey); Nanotechnology Application and Research Center, Adnan Menderes University, 09100 Aydın (Turkey); Aktürk, Ethem, E-mail: ethem.akturk@adu.edu.tr [Department of Physics, Adnan Menderes University, 09100 Aydın (Turkey); Nanotechnology Application and Research Center, Adnan Menderes University, 09100 Aydın (Turkey)

    2016-09-01

    This paper presents a study on the adsorption of alkali and alkaline-earth metal atoms on single-layer stanene with different levels of coverage using first-principles plane wave calculations within spin-polarized density functional theory. The most favorable adsorption site for alkali atoms (Li, Na, K) were found to be the hollow site similar to other group IV single-layers, but the case of alkaline-earths on stanene is different from silicene and germanene. Whereas Mg and Ca are bound to stanene at hollow site, the bridge site is found to be energetically favorable for Be adatom. All adsorbed atoms are positively charged due to the charge transfer from adatom to stanene single-layer. The semimetallic bare stanene become metallic except for Be adsorption. The Beryllium adsorption give rise to non-magnetic semiconducting ground state. Our results illustrate that stanene has a reactive and functionalizable surface similar to graphene or silicene. - Highlights: • Alkali and alkaline-earth metal atoms form stronger bonds with stanene compared to other group IV monolayers. • Semi-metallic stanene becomes nonmagnetic metal for Li, Na, K, Mg, and Ca atoms adsorption. • Semi-metallic stanene becomes nonmagnetic semiconductor with 94 meV band gap for Be atom adsorption.

  8. 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.

  9. Alkaline-earth metal bicarbonates as lixiviants for uranium (VI) under CO2 sparging

    International Nuclear Information System (INIS)

    Vaziri, F.; White, D.A.

    1989-01-01

    In recent years it has become apparent that uranium is significantly soluble in solutions of alkaline-earth metal bicarbonates -particularly those of magnesium and calcium. A system has been proposed by previous authors in which milled uranium ore is leached in a medium to which an oxidizing agent, the metal hydroxide and CO 2 are added. The alkaline-earth metal hydroxides are much more readily soluble in this medium than the corresponding carbonates. Magnesium and calcium bicarbonates are quite soluble in aqueous media at neutral or nearly neutral pH. The pH determines the relative quantities of bicarbonate and carbonate ions in the system. Even if the pH is quite low, small amounts of carbonate ion are present that can complex with the uranyl ion to produce anionic uranyl complexes. Both UO 2 (CO 3 ) 2 2- and UO 2 (CO 3 ) 3 4- complexes are known and both have a very high stability constant. Despite the appearance of several patents on the use of alkaline-earth metal ions in carbonate media as uranium lixiviants, little theoretical or experimental work on the system has been published. In view of the potential of these systems for cheap, large-scale dissolution of uranium the present contribution will discuss the theory behind this method and provide some experimental data to verify the theoretical treatment. (author)

  10. Synthesis and physicochemical investigation of complexes of rare earth, alkaline earth elements and copper with some β-diketones

    International Nuclear Information System (INIS)

    Nichiporuk, R.V.; Pechurova, N.I.; Snezhko, N.I.; Martynenko, L.I.; Kaul', A.R.; Zanina, A.S.; Shergina, S.I.; Sokolov, I.E.

    1991-01-01

    Complexes of rare earth, alkaline earth elements and copper with 2-methoxy-2,6,6-trimethylheptanedion-3,5 as well as complexes of yttrium and barium with 2-methoxy-2,6-dimethylheptanedion-3,5 were synthesized. Prepared complexes were investigated by the methods of chemical, thermal, X-ray phase analyses, IR spectroscopy. Complex sublimation was studied at 10 -1 -10 -2 mm Hg. Complexes of rare earths and copper don't change their composition during sublimation, and sublimation of hydrated complexes of barium, strontium and calcium leads to formation of anhydrous complexes. All prepared complexes are able to transsublimate multiply and qualitatively without change of composition. All isolated complexes can be used for preparation of film oxide coatings by CVD method

  11. Effect of alkaline metal cations on the ionic structure of cryolite melts: Ab-initio NpT MD study

    Science.gov (United States)

    Bučko, Tomáš; Šimko, František

    2018-02-01

    Ab initio molecular dynamics simulations in an NpT ensemble have been performed to study the role of alkaline metal cations (Me = Li, Na, K, Rb) on the structure and vibrational properties of melts of Me-cryolites (Me3AlF6) at T = 1300 K. In all melts examined in this work, the species AlF52 - has been found to be formed at the highest abundance [from 58% (Li) to 70% (Na)] among the Al-containing anionic clusters. The concentration of clusters AlF4- increases with the size of cations while that of anions AlF63 - follows the opposite trend and it becomes negligible in the melts of the K- and Rb-cryolites. The computed percentage of the Al atoms participating in the formation of dimers Al2Fm6 -m bridged via common F atoms is significant only in the case of Li- and Na-cryolites (16% and 10%, respectively) and the formation of even larger aggregates is found to be unlikely in all four melts. The percentage of the F atoms that are not bound to Al is ˜20% in all four melts and the ions formed by Me+ and F- are found to be only short-lived. Vibrational analysis has been performed using the velocity autocorrelation functions computed for the Cartesian and selected internal coordinates describing Raman-active symmetric stretching vibrations of different AlFn species. The results of vibrational analysis allowed us to identify trends in the variation of positions and shapes of peaks corresponding to the anionic fragments AlF4-, AlF52 -, and AlF63 - with the size of cations, and these trends are found to be consistent with those deduced from the available Raman spectroscopy experiments. Our findings represent a new insight into the properties of cryolite melts, which will be useful for the interpretation of experimental data.

  12. 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

  13. Isotope exchange between alkaline earth metal hydroxide and HTO water in the equilibrium state

    International Nuclear Information System (INIS)

    Imaizumi, H.; Gounome, J.; Kano, N.

    1997-01-01

    In order reveal to what extent tritium ( 3 H or T) can be incorporated into hydroxides, the isotope exchange reaction (OT-for-OH exchange reaction) between each alkaline earth metal hydroxide (M(OH) 2 ), where M means alkaline earth metal (M=Ca, Sr or Ba) and HTO water was observed homogeneously at 30 deg C under equilibrium after mixing. Consequently, the followings were obtained: a quantitative relation between the electronegativity of each M ion and the ability (of the M ion) incorporating OT - into the M hydroxide can be found and the ability is small when the temperature is high, the exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the M ion in the M hydroxide is great, as for the dissociation of HTO water, it seems that formula (HTO ↔ T + + OH - ) is more predominant than the formula (HTO ↔H + + OT - ) when the temperature is high and the method used in this work is useful to estimate the reactivity of a certain alkaline material. (author)

  14. Alkaline earth-based coordination polymers derived from a cyclotriphosphazene-functionalized hexacarboxylate

    International Nuclear Information System (INIS)

    Ling, Yajing; Bai, Dongjie; Feng, Yunlong; He, Yabing

    2016-01-01

    Combination of hexakis(4-carboxylatephenoxy)cyclotriphosphazene with alkaline earth ions of increasing ionic radii (Mg 2+ , Ca 2+ and Ba 2+ ) under different solvothermal conditions yielded three new coordination polymers, and their crystal structures were determined by single-crystal X-ray diffraction analysis. The magnesium compound displays a three dimensional (3D) network structure constructed from the deprotonated ligand and the secondary building block Mg(COO) 4 , which can be rationalized as a (4,6)-connected topological net with the Schläfli symbol of (4 4 ·6 2 ) 3 (4 9 ·6 6 ) 2 . The calcium compound consists of 1D infinite “Ca-O” inorganic chains connected by the deprotonated ligands to from a 3D framework. The barium compound exhibits a 3D framework in which 1D “Ba-O” inorganic chains are connected together by the deprotonated organic linkers. Due to the semi-rigid nature, the ligand adopts distinctly different conformations in the three compounds. The metal ions’ influence exerted on the final structure of the resulting coordination polymers is also discussed. When the radii of alkaline earth ions increases descending down the group from Mg(II) to Ba(II), the coordination number becomes larger and more versatile: from 6 in the magnesium compound, to 6,7 and 10 in the calcium compound, and to 8 and 9 in the barium compound, thus substantially influencing the resulting final framework structures. Also, the photophysical properties were investigated systematically, revealing that the three compounds are photoluminscent in the solid state at room temperature. This work demonstrates that although the multiplicity of conformation in the hexacarboxylate ligand based on the inorganic scaffold cyclotriphosphazene makes it difficult to predict how this ligand will form extended network, but provides unique opportunities for the formation of diverse inorganic-organic hybrids exhibiting rich structural topologies. - Graphical abstract: Three alkaline

  15. First-principles calculation on oxygen ion migration in alkaline-earth doped La2GeO5

    International Nuclear Information System (INIS)

    Thuy Linh, Tran Phan; Sakaue, Mamoru; Aspera, Susan Meñez; Alaydrus, Musa; Wungu, Triati Dewi Kencana; Hoang Linh, Nguyen; Kasai, Hideaki; Mohri, Takahiro; Ishihara, Tatsumi

    2014-01-01

    By using first-principles calculations based on the density functional theory, we investigated the doping effects of alkaline-earth metals (Ba, Sr and Ca) in monoclinic lanthanum germanate La 2 GeO 5 on its oxygen ion conduction. Although the lattice parameters of the doped systems changed due to the ionic radii mismatch, the crystal structures remained monoclinic. The contribution of each atomic orbital to electronic densities of states was evaluated from the partial densities of states and partial charge densities. It was confirmed that the materials behaved as ionic crystals comprising of cations of La and dopants and anions of oxygen and covalently formed GeO 4 . The doping effect on the activation barrier for oxygen hopping to the most stable oxygen vacancy site was investigated by the climbing-image nudged elastic band method. By tracing the charge density change during the hopping, it was confirmed that the oxygen motion is governed by covalent interactions. The obtained activation barriers showed excellent quantitative agreements with an experiment for the Ca- and Sr-doped systems in low temperatures as well as the qualitative trend, including the Ba-doped system. (paper)

  16. Promotion of the oxidation of carbon monoxide at stepped platinum single-crystal electrodes in alkaline media by lithium and beryllium cations.

    Science.gov (United States)

    Stoffelsma, Chantal; Rodriguez, Paramaconi; Garcia, Gonzalo; Garcia-Araez, Nuria; Strmcnik, Dusan; Marković, Nenad M; Koper, Marc T M

    2010-11-17

    The role of alkali cations (Li(+), Na(+), K(+), Cs(+), and Be(2+)) on the blank voltammetric response and the oxidative stripping of carbon monoxide from stepped Pt single-crystal electrodes in alkaline media has been investigated by cyclic voltammetry. A strong influence of the nature of the cation on both the blank voltammetric profile and the CO oxidation is observed and related to the influence of the cation on the specific adsorption of OH on the platinum surface. Especially Li(+) and Be(2+) cations markedly affect the adsorption of OH and thereby have a significant promoting effect on CO(ads) oxidation. The voltammetric experiments suggest that, on Pt(111), the influence of Li(+) (and Be(2+)) is primarily through a weakening of the repulsive interactions between the OH in the OH adlayer, whereas in the presence of steps also, the onset of OH adsorption is at a lower potential, both on steps and on terraces.

  17. Superconductivity in alkaline earth-substituted La2CuO/sub 4-y/

    International Nuclear Information System (INIS)

    Bednorz, J.G.; Mueller, K.A.; Takashige, M.

    1987-01-01

    La 2 CuO/sub 4-y/ ceramics containing a few percent of Ca 2+ , Sr 2+ , and Ba 2+ ions have been prepared. Resistivity and susceptibility measurements exhibit superconductive onsets (as in earlier Ba 2+ -containing samples). The onset temperature La 2 CuO/sub 4-y/ with Sr 2+ is higher and its superconductivity-induced diamagnetism larger than that found with Ba 2+ and Ca 2+ . This is proof that the electronic change resulting from alkaline earth-doping, rather than the size effect, is responsible for superconductivity. The ionic radius of Sr 2+ is close to that of La 3+ for which it presumably substitutes

  18. Subthermal linewidths in photoassociation spectra of cold alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    Machholm, Mette; Julienne, Paul S.; Suominen, Kalle-Antti

    2002-01-01

    Narrow s-wave features with subthermal widths are predicted for the 1 Π g photoassociation spectra of cold alkaline-earth-metal atoms. The phenomenon is explained by numerical and analytical calculations. These show that only a small subthermal range of collision energies near threshold contributes to the s-wave features that are excited when the atoms are very far apart. The resonances survive thermal averaging, and may be detectable for Ca cooled near the Doppler cooling temperature of the 4 1 P 1 S laser-cooling transition

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

    International Nuclear Information System (INIS)

    Warminska, Dorota; Wawer, Jaroslaw; Grzybkowski, Waclaw

    2010-01-01

    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.

  20. Hyperfine structure of 2Σ molecules containing alkaline-earth-metal atoms

    Science.gov (United States)

    Aldegunde, Jesus; Hutson, Jeremy M.

    2018-04-01

    Ultracold molecules with both electron spin and an electric dipole moment offer new possibilities in quantum science. We use density-functional theory to calculate hyperfine coupling constants for a selection of molecules important in this area, including RbSr, LiYb, RbYb, CaF, and SrF. We find substantial hyperfine coupling constants for the fermionic isotopes of the alkaline-earth-metal and Yb atoms. We discuss the hyperfine level patterns and Zeeman splittings expected for these molecules. The results will be important both to experiments aimed at forming ultracold open-shell molecules and to their applications.

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

    Science.gov (United States)

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

    2011-01-01

    The present study investigates the binding properties of four dansyl substituted aza-crown ethers with alkali, alkaline earth metal ions and ammonium. The influence of the solvent polarity and protonation on the photophysical properties of the compounds was studied by UV/Vis and fluorescence methods. The host species caused only slight changes on the absorption spectra of the ligands. The fluorescence changes were more pronounced and concentration dependent thus allowing to calculate the binding constants of the process. The most stable complex under our working conditions was the one between Ba2+ and DNS18C6. PMID:21738561

  2. Two-photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

    International Nuclear Information System (INIS)

    Magno, Wictor C.; Cavasso Filho, Reinaldo L.; Cruz, Flavio C.

    2003-01-01

    The possibility of laser cooling of alkaline-earth-metal atoms and ytterbium atoms using a two-photon transition is analyzed. We consider a 1 S 0 - 1 S 0 transition with excitation in near resonance with the 1 P 1 level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for calcium, for example, two-photon cooling can be used to achieve a Doppler limit of 123 μK. The efficiency of this cooling scheme and the main loss mechanisms are analyzed

  3. Novel Extraction Process Of Rare Earth Elements From NdFeB Powders Via Alkaline Treatment

    Directory of Open Access Journals (Sweden)

    Chung K.W.

    2015-06-01

    Full Text Available The alkaline treatment of NdFeB powders in NaOH solution at various equivalent amounts of NaOH at 100°C was performed. The resultant powders were then leached in 0.5M H2SO4 solution at 25°C for 2 minutes. At 5 equivalents of NaOH, neodymium in NdFeB powders was partially transformed to neodymium hydroxide. The transformation of neodymium to neodymium hydroxide actually occurred at 10 equivalents of NaOH and was facilitated by increasing the equivalent of NaOH from 10 to 30. In addition, iron was partially transformed to magnetite during the alkaline treatment, which was also promoted at a higher equivalent of NaOH. The leaching yield of neodymium from alkaline-treated powders was increased with an increasing equivalent of NaOH up to 10; however, it slightly decreased with the equivalent NaOH of over 10. The leaching yield of iron was inversely proportional to that of rare earth elements. NdFeB powders treated at 10 equivalents of NaOH showed a maximum leaching yield of neodymium and dysprosium of 91.6% and 94.6%, respectively, and the lowest leaching yield of iron of 24.2%, resulting in the highest selective leaching efficiency of 69.4%.

  4. Change of sulfide inclusions in steel microalloying with rare earth and alkaline-earth elements

    International Nuclear Information System (INIS)

    Averin, V.V.; Polonskaya, S.M.; Chistyakov, V.F.

    1977-01-01

    The conditions for the formation of sulfides in molten and solid iron were determined by considering the thermodynamics of the interaction of sulfur and of oxygen with various components. It was shown in casting of low-carbon steel under a blanket of slag-forming briquettes, calcium of the silicocalcium partly passes to iron and to the sulfide phase. The sulfide inclusions with calcium in rolling become lens-shaped and acquire a greater strength, proportional to the content of calcium, thus ensuring a lesser anisotropy of steel. The change in the shape and the composition of sulfide inclusions effects the fracture of the metal which changes in type from separation along lamellar inclusions to a plastic fracture, i.e., enhances resilience. It is thus noted that rare-earth and alkali-earth elements, in particular, cerium and calcium are promising agents for desulfurating molten iron

  5. Preparation and physical properties of rare earth, alkaline earth, and transition metal ternary chalcogenides

    International Nuclear Information System (INIS)

    Georgobiani, A.N.

    1997-01-01

    A study was made on current-voltage characteristics, temperature dependences of electric conductivity and currents of thermoinduced depolarization of monocrystals, including EuGa 2 S 4 and (Ga 2 S 3 ) 1-x (Eu 2 O 3 ) x solid solutions. It is shown that these compounds, activated by europium, cerium, neodymium and other rare earths, manifest effective luminescence under the effect of ultraviolet and X-radiation, as well as under the effect of electron beams and electric field

  6. 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

  7. Tensorial analysis of the long-range interaction between metastable alkaline-earth-metal atoms

    International Nuclear Information System (INIS)

    Santra, Robin; Greene, Chris H.

    2003-01-01

    Alkaline-earth-metal atoms in their lowest (nsnp) 3 P 2 state are exceptionally long lived and can be trapped magnetically. The nonspherical atomic structure leads to anisotropic long-range interactions between two metastable alkaline-earth-metal atoms. The anisotropy affects the rotational motion of the diatomic system and couples states of different rotational quantum numbers. This paper develops a tensorial decomposition of the most important long-range interaction operators, and a systematic inclusion of molecular rotations, in the presence of an external magnetic field. This analysis illuminates the nature of the coupling between the various degrees of freedom. The consequences are illustrated by application to a system of practical interest: metastable 88 Sr. Using atomic parameters determined in a nearly ab initio calculation, we compute adiabatic potential-energy curves. The anisotropic interatomic interaction, in combination with the applied magnetic field, is demonstrated to induce the formation of a long-range molecular potential well. This curve correlates to two fully polarized, low-field seeking atoms in a rotational s-wave state. The coupling among molecular rotational states controls the existence of the potential well, and its properties vary as a function of magnetic-field strength, thus allowing the scattering length in this state to be tuned. The scattering length of metastable 88 Sr displays a resonance at a field of 339 G

  8. Steam Gasification of Sawdust Biochar Influenced by Chemical Speciation of Alkali and Alkaline Earth Metallic Species

    Directory of Open Access Journals (Sweden)

    Dongdong Feng

    2018-01-01

    Full Text Available The effect of chemical speciation (H2O/NH4Ac/HCl-soluble and insoluble of alkali and alkaline earth metallic species on the steam gasification of sawdust biochar was investigated in a lab-scale, fixed-bed reactor, with the method of chemical fractionation analysis. The changes in biochar structures and the evolution of biochar reactivity are discussed, with a focus on the contributions of the chemical speciation of alkali and alkaline earth metallic species (AAEMs on the steam gasification of biochar. The results indicate that H2O/NH4Ac/HCl-soluble AAEMs have a significant effect on biochar gasification rates. The release of K occurs mainly in the form of inorganic salts and hydrated ions, while that of Ca occurs mainly as organic ones. The sp3-rich or sp2-sp3 structures and different chemical-speciation AAEMs function together as the preferred active sites during steam gasification. H2O/HCl-soluble AAEMs could promote the transformation of biochar surface functional groups, from ether/alkene C-O-C to carboxylate COO− in biochar, while they may both be improved by NH4Ac-soluble AAEMs. H2O-soluble AAEMs play a crucial catalytic role in biochar reactivity. The effect of NH4Ac-soluble AAEMs is mainly concentrated in the high-conversion stage (biochar conversion >30%, while that of HCl-soluble AAEMs is reflected in the whole activity-testing stage.

  9. Raman and 11B nuclear magnetic resonance spectroscopic studies of alkaline-earth lanthanoborate glasses

    International Nuclear Information System (INIS)

    Brow, R.K.; Tallant, D.R.; Turner, G.L.

    1996-01-01

    Glasses from the RO·La 2 O 3 ·B 2 O 3 (R = Mg, Ca, and Ba) systems have been examined. Glass formation is centered along the metaborate tie line, from La(BO 2 ) 3 to R(BO 2 ) 2 . Glasses generally have transition temperatures >600 C and expansion coefficients between 60 x 10 -7 /C and 100 x 10 -7 /C. Raman and solid-state nuclear magnetic resonance spectroscopies reveal changes in the metaborate network that depend on both the [R]:[La] ratio and the type of alkaline-earth ion. The fraction of tetrahedral sites is generally reduced in alkaline-earth-rich glasses, with magnesium glasses possessing the lowest concentration of B[4]. Raman spectra indicate that, with increasing [R]:[La] ratio, the preferred metaborate anion changes from a double-chain structure associated with crystalline La(BO 2 ) 3 to the single-chain and ring metaborate anions found in crystalline R(BO 2 ) 2 phases. In addition, disproportionation of the metaborate anions leads to the formation of a variety of other species, including pyroborates with terminal oxygens and more-polymerized species, such as diborates, with tetrahedral borons. Such structural changes are related to the ease of glass formation and some of the glass properties

  10. Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

    Science.gov (United States)

    Liu, Yong-Qiang; Yu, Hong

    2017-04-01

    A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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

    2016-04-05

    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.

  12. Cation exchange separation of 16 rare earth metals by microscale high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Ishii, D.; Hirose, A.; Iwasaki, Y.

    1978-01-01

    The separation of rare earth metals has been studied with a microcolumn of 0.5 mm i.d. and 75 mm length, packed with TSK LS-212 high-performance cation exchange resin. A micro-feeder (Model MF-2, from Azumadenki Kogyo) was used to drive carrier and sample solutions through the ion exchange column and detection cell. By combining a 250 μl syringe and a 0.5 mm i.d. sampling tube the micro-feeder, 0.1-1.0 μl rare earth metals were separated within 38 min, using only 304 μl of 0.4M α-hydroxy-isobutyric acid solution adjusted to pH 3.1-6.0 with ammonia solution as gradient carrier solution. The gradient elution was successfully performed by applying a new technique developed for microscale liquid chromatography. (author)

  13. Separation of strontium ions from other alkaline earth metal ions using masking reagent

    International Nuclear Information System (INIS)

    Komatsu, Y.

    1996-01-01

    Cs + and Sr 2+ have been well known as serious elements in high level radioactive waste. Separation of Cs + has already been successful when using an ion-exchange method from solution in the presence of other alkali metal ions. The separation of Sr 2+ is, however, not so easy by any known separation method such as solvent-extraction and ion-exchange methods. This is because Sr 2+ is in the middle of the selectivity series, which is Mg 2+ > Ca 2+ > Sr 2+ > Ba 2+ for the solvent-extraction method and Ba 2+ > Sr 2+ > Ca 2+ > Mg 2+ for the ion- exchange method. In the present study, separation of strontium from other alkaline earth metal ions was studied by a combined use of three types of separation methods at 298 K: the solvent-extraction method was applied for the first separation, in which thenoyltrifluoroacetone (TTA, extractant) and trioctylphosphine oxide ( TOPO, adduct forming ligand) were used for the organic phase of the system. The separation factors for each combination of four alkaline earth metal ions were determined by the values of the distribution ratio. The Mg 2+ was well separated from Sr 2+ by the TTA-TOPO system. However, the separation of the combinations of Ca 2+ -Sr 2+ and Sr 2+ -Ba 2+ was not complete by the above solvent-extraction system. The second separation method, an ion-exchange method was applied using dihydrogen tetratitanate hydrate fibers (H 2 Ti 4 O 9 nH 2 O) as an ion exchanger to separate Sr 2+ and Ba 2+ . The separation factors for each combination of four alkaline earth metal ions were calculated by the values of the distribution coefficients. Ba 2+ was well separated from Sr 2+ by the ion-exchange method. To separate Ca 2+ and Sr 2+ , however, a modified solvent-extraction method was finally used in which H 2 Ti 4 O 9 nH 2 O was used as a masking reagent of Sr 2+ . After the dihydrogen tetratitanate hydrate fibers were contacted with the aqueous solution containing Ca 2+ and Sr 2+ , the organic solution containing TTA and TOPO

  14. REDOX BEHAVIOR AND DIFFUSIVITY OF ANTIMONY AND CERIUM ION IN ALKALI ALKALINE EARTH SILICATE GLASS MELTS

    Directory of Open Access Journals (Sweden)

    K. D. Kim

    2010-03-01

    Full Text Available Redox behavior and diffusivity of antimony and cerium ion in alkali alkaline earth silicate CRT (Cathode Ray Tube model glass melts were studied by means of square wave voltammetry under the frequency range of 5-1000 Hz and in the temperature range of 800-1400°C. According to voltammogram, peaks due to Sb³⁺/Sb⁰ were positioned in the negative potential region while peaks due to Sb⁵⁺/Sb³⁺ and Ce⁴⁺/Ce³⁺ were found in the positive potential region. By using some equations, correlation for peak potential versus temperature and peak current versus reciprocal frequency was examined, respectively. Their correlation showed a linear relation in the applied temperature and frequency range. Based on the linear relationship, thermodynamic and kinetic properties for each redox reaction were suggested.

  15. Superexchange-mediated magnetization dynamics with ultracold alkaline-earth atoms in an optical lattice

    International Nuclear Information System (INIS)

    Zhu Shaobing; Qian Jun; Wang Yuzhu

    2017-01-01

    Superexchange and inter-orbital spin-exchange interactions are key ingredients for understanding (orbital) quantum magnetism in strongly correlated systems and have been realized in ultracold atomic gases. Here we study the spin dynamics of ultracold alkaline-earth atoms in an optical lattice when the two exchange interactions coexist. In the superexchange interaction dominating regime, we find that the time-resolved spin imbalance shows a remarkable modulated oscillation, which can be attributed to the interplay between local and nonlocal quantum mechanical exchange mechanisms. Moreover, the filling of the long-lived excited atoms affects the collapse and revival of the magnetization dynamics. These observations can be realized in state-dependent optical lattices combined with the state-of-the-art advances in optical lattice clock spectroscopy. (paper)

  16. Prolonged QT Syndrome and Seizure Secondary to Alkaline Earth Metal Deficiency: A Case Report

    Directory of Open Access Journals (Sweden)

    A. McKinney

    2011-01-01

    Full Text Available Introduction. Alkaline earth metal deficiency is recognized as a cause of both seizure and long QT syndrome. Their deficiency can have significant repercussions on the function of cells, tissues, and organs of the body. An understanding of the role of electrolytes allows an appreciation of the significance of depleted levels on cell function. Case Report. A 65-year-old lady was admitted with symptoms of chest discomfort, vomiting, increased stoma output, and dizziness. Two days following admission she suffered a tonic-clonic seizure. ECG review demonstrated a prolonged QTc interval, raising the possibility of an underlying Torsades de Pointes as the precipitant. This was attributed to electrolyte disturbance arising as a result of multiple aetiologies. Discussion. This paper highlights the multisystem effects of electrolyte disturbance, with emphasis upon its role in precipitating cardiac arrhythmia and neurological symptoms.

  17. Topological Fractional Pumping with Alkaline-Earth-Like Atoms in Synthetic Lattices

    Science.gov (United States)

    Taddia, Luca; Cornfeld, Eyal; Rossini, Davide; Mazza, Leonardo; Sela, Eran; Fazio, Rosario

    2017-06-01

    Alkaline-earth(-like) atoms, trapped in optical lattices and in the presence of an external gauge field, can form insulating states at given fractional fillings. We will show that, by exploiting these properties, it is possible to realize a topological fractional pump. Our analysis is based on a many-body adiabatic expansion, on simulations with time-dependent matrix product states, and, for a specific form of atom-atom interaction, on an exactly solvable model of fractional pump. The numerical simulations allow us to consider a realistic setup amenable of an experimental realization. As a further consequence, the measure of the center-of-mass shift of the atomic cloud would constitute the first measurement of a many-body Chern number in a cold-atom experiment.

  18. IRON REDOX EQUILIBRIUM AND DIFFUSIVITY IN MIXED ALKALI-ALKALINE EARTH-SILICA GLASS MELTS

    Directory of Open Access Journals (Sweden)

    KI-DONG KIM

    2011-03-01

    Full Text Available Dependence of redox behavior and diffusivity of iron on temperature and composition was studied in mixed alkali-alkaline earth-silica glass melts by means of square wave voltammetry (SWV. The voltammograms showed that irrespective of K2O/(Na2O+K2O the peak potential due to Fe3+/Fe2+ moved toward negative direction with temperature decrease and the peak current showed a strong dependence on frequency at constant temperature. Iron diffusion coefficient versus melt viscosity showed a good linearity. The compositional dependence showed that the peak potential shifted to the positive direction with increase of K2O but a typical mixed alkali effect occurred in iron diffusion either at constant temperature or at constant viscosity.

  19. Enhanced NO2 abatement by alkaline-earth modified g-C3N4 nanocomposites for efficient air purification

    Science.gov (United States)

    Papailias, Ilias; Todorova, Nadia; Giannakopoulou, Tatiana; Karapati, Sofia; Boukos, Nikos; Dimotikali, Dimitra; Trapalis, Christos

    2018-02-01

    The emission of nitrogen dioxide (NO2) is a major problem encountered in photocatalytic NOx removal for air purification. Although the oxidation of nitric oxide (NO) has been extensively studied, the elimination of NO2 byproduct is still in preliminary stage. In this work, alkaline-earth modified graphitic carbon nitride (g-C3N4) is proposed for efficient NOx removal by minimizing the emission of NO2 during the NO oxidation process. The novel photocatalysts were synthesized by annealing mixtures of melamine and various alkaline-earth acetates (magnesium, calcium and barium acetate) at 550 °C for 3 h. The specific surface area of the photocatalysts varied between 4.65 and 11.81 m2/g. The formation of MgO, CaCO3 and BaCO3 was demonstrated by XPS and FT-IR analyses. The initial concentration of each alkaline-earth precursor was 5 and 10 wt%, while the final metal concentration in the nanocomposites was in the range of 7.19-22.39 wt%. The modified photocatalysts showed slightly reduced NO oxidation ability. However, the overall air quality was significantly improved by restraining the NO2 emission. The results were related to the basic character of the nanocomposites due to the presence of alkaline-earths and their enhanced NO2 adsorption capability.

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

    KAUST Repository

    Zhang, J.-Y.; Babb, J. F.; Mitroy, J.; Sadeghpour, H. R.; Schwingenschlö gl, Udo; Yan, Z.-C.

    2013-01-01

    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.

  1. 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.

  2. Removal of alkaline-earth elements by a carbonate precipitation in a chloride molten salt

    International Nuclear Information System (INIS)

    Yung-Zun Cho; In-Tae Kim; Hee-Chui Yang; Hee-Chui Eun; Hwan-Seo Park; Eung-Ho Kim

    2007-01-01

    Separation of some alkaline-earth chlorides (Sr, Ba) was investigated by using carbonate injection method in LiCl-KCl eutectic and LiCl molten salts. The effects of the injected molar ratio of carbonate([K 2 (or Li 2 )CO 3 /Sr(or Ba)Cl 2 ]) and the temperature(450-750 deg.) on the conversion ratio of the Sr or Ba carbonate were determined. In addition, the form of the Sr and Ba carbonate resulting from the carbonation reaction with carbonates was identified via XRD and SEM-EDS analysis. In these experiments, the carbonate injection method can remove Sr and Ba chlorides effectively over 99% in both LiCl-KCl eutectic and LiCl molten salt conditions. When Sr and Ba were co-presented in the eutectic molten salt, they were carbonated in a form of Ba 0.5 Sr 0.3 CO 3 . And when Sr was present in LiCl molten salt, it was carbonated in the form of SrCO 3 . Carbonation ratio increased with a decreasing temperature and it was more favorable in the case of a K 2 CO 3 injection than that of Li 2 CO 3 . Based on this experiment, it is postulated that carbonate precipitation method has the potential for removing alkali-earth chlorides from LiCl-KCl eutectic and LiCl molten salts. (authors)

  3. Effect of ratio of calcium and rare earth cations in Y zeolites on their catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Mortikov, E S; Leont' ev, A S; Masloboev, A A; Mirzabekova, N V; Kononov, N F; Minachev, Kh M [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1976-03-01

    Optimum ratios between Ca/sup 2 +/ and rare earth elements (REE) in zeolite were studied. Five samples of the catalyst with different Ca/REE ratios were prepared from granulated zeolite NaJ with the ratio SiO/sub 2/:Al/sub 2/O/sub 3/ = 4.7, formed from Al/sub 2/O/sub 3/. The initial REE solution was a mixture of Ce, La, Pr and Nd chlorides with the same catalytic properties. The catalyst activity was established by ethyl benzene (EB) yield. The work has resulted in information on catalytic properties of J zeolites with different contents of Ca and REE cations in the process of benzene alkylating with ethylene.

  4. 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.

  5. Physical and spectroscopic studies of Cr{sup 3+} doped mixed alkaline earth oxide borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Samdani, E-mail: samdanimohd82@gmail.com [Department of Engineering, Salalah College of Technology, Salalah (Oman); Ramadevudu, G. [Department of Physics, Vasavi College of Engineering, Ibrahimbagh, Hyderabad 500031, Telangana (India); Chary, M. Narasimha; Shareefuddin, Md. [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India)

    2017-01-15

    A series of mixed alkaline earth oxide glasses xMgO-(30-x)BaO-69.8B{sub 2}O{sub 3}-0.2Cr{sub 2}O{sub 3} were prepared and studied using electron paramagnetic resonance (EPR), optical absorption, Raman spectroscopy and photoluminescence experimental techniques. The optical absorption spectra revealed the characteristic octahedral symmetry of Cr{sup 3+}ions through three broad band transitions {sup 4}A{sub 2g}(F)→ {sup 4}T{sub 2g}(F), {sup 4}A{sub 2g}(F)→ {sup 4}T{sub 1g}(F), and {sup 4}A{sub 2g}(F)→ {sup 2}T{sub 1g}(P). The crystal field (Dq) and Racah parameters (B and C), the optical band gap and Urbach energies of the glass samples were also reported along with the physical properties like density and molar volume. In the EPR spectra three resonance signals corresponding to Cr3+ ions were observed. A broad signal with g = 5.110 was observed which belongs to the isolated Cr3+ centers localized in the strongly distorted octahedral (rhombic) sites of the glass network, a narrow signal (g = 1.960) corresponding to the Cr{sup 3+} centers in the weekly distorted (cubic) sites of the glass network, and a third very broad signal (g = 2.210) was also observed corresponding to Cr{sup 3+}- Cr{sup 3+} paired centers coupled by magnetic dipolar interaction. Another resonance signal with effective value g ≈ 4.220 was attributed to Fe{sup 3+} ions impurity. The number of spins (N) participating in the resonance and susceptibility (χ) values at room temperature were reported and their values varied in a non-linear manner with the composition exhibiting mixed oxide effect. The estimated molecular bonding coefficients (α) values indicated stronger ionic contribution. The Raman spectral investigations were carried out. The Photoluminescence spectra bands near 690 and 750 nm correspond to the Cr{sup 3+} centers in high and low field sites respectively. - Highlights: • Spectroscopic studies were made on alkaline earth borate glasses. • Three resonance signals

  6. Formation of H a - hydrogen centers upon additive coloration of alkaline-earth fluoride crystals

    Science.gov (United States)

    Radzhabov, E. A.; Egranov, A. V.; Shendrik, R. Yu.

    2017-06-01

    The mechanism of coloration of alkaline-earth fluoride crystals CaF2, SrF2, and BaF2 in calcium vapors in an autoclave with a cold zone is studied. It was found that the pressure in the autoclave upon constant evacuation by a vacuum pump within the temperature range of 500-800°C increases due to evaporation of metal calcium. In addition to the optical-absorption bands of color centers in the additively colored undoped crystals or to the bands of divalent ions in the crystals doped with rare-earth Sm, Yb, and Tm elements, there appear intense bands in the vacuum ultraviolet region at 7.7, 7.0, and 6.025 eV in CaF2, SrF2, and BaF2, respectively. These bands belong to the Ha - hydrogen centers. The formation of hydrogen centers is also confirmed by the appearance of the EPR signal of interstitial hydrogen atoms after X-ray irradiation of the additively colored crystals. Grinding of the outer edges of the colored crystals leads to a decrease in the hydrogen absorption-band intensity with depth to complete disappearance. The rate of hydrogen penetration inside the crystal is lower than the corresponding rate of color centers (anion vacancies) by a factor of tens. The visible color density of the outer regions of the hydrogen-containing crystals is several times lower than that of the inner region due to the competition between the color centers and hydrogen centers.

  7. Distributions of alkali metals, alkaline earth metals and halogens in cabbage leaves

    International Nuclear Information System (INIS)

    Tsukada, Hirofumi; Takeda, Akira; Hasegawa, Hidenao

    2007-01-01

    The distributions of stable elements in plant components provide useful information for understanding the behavior of radionuclides in plants. An entire cabbage plant sample was collected from an experimental field, and the distributions of alkali metals (K, Rb and Cs), alkaline earth metals (Ca, Sr and Ba) and halogens (Cl and I) were determined for cabbage leaves at different positions. The concentration of Cs in outer (older) cabbage leaves was higher than that in inner (younger) leaves, but the distributions of K and Rb concentrations were relatively similar in cabbage leaves, independent of leaf positions. The concentration of Sr in older cabbage leaves was one order of magnitude higher than that in younger leaves. The distributions of Ca, Ba and Sr concentrations in the plant followed a similar pattern. The concentrations of halogens were also very rich in the outer leaves. The percentage distributions of Cs, Sr, Cl and I in the inedible (extreme outer) leaves were 77, 91, 93 and 96% of the total content in the leaf part, respectively. These results show that the inedible plant components are important for understanding the transfer of the radioactive Cs, Sr Cl and I in soil-plant systems. (author)

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

    International Nuclear Information System (INIS)

    Vilchis-Granados, J.; Granados-Correa, F.; Barrera-Díaz, C.E.

    2013-01-01

    This work examines the surface fractal dimensions (D 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 2 -physisorption measurements. Surface fractal dimensions were determined using single N 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 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.

  9. Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick J.

    1996-01-01

    A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

  10. Nitridomanganates of alkaline-earth metals. Synthesis, structure, and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, Alexander

    2016-12-02

    The main goal of the present work was the synthesis of alkaline-earth nitridomanganates (AE{sub x}Mn{sub y}N{sub z}) with extended anionic structures and the characterization of their electronic and magnetic properties. Up to now, only compounds with isolated nitridomanganate anions have been reported in the discussed ternary systems. A systematic exploratory synthesis, employing high-temperature treatment of AE nitrides and Mn under controlled N2 pressure, yielded more than ten new nitridomanganates. Their crystal structures contain anionic building blocks of different dimensionalities, ranging from isolated species to three-dimensional frameworks. In general, the formation of Mn-rich compositions was found to be driven by the emergence of Mn-Mn interactions, which creates a link between nitridometalates and transition-metal-rich binary nitrides. The obtained nitridomanganates display a plethora of interesting phenomena, such as large spin-orbit coupling, magnetic frustration, quenching of magnetism due to Mn-Mn interactions, and metal-insulator transition.

  11. Alkaline earth metal and samarium co-doped ceria as efficient electrolytes

    Science.gov (United States)

    Ali, Amjad; Raza, Rizwan; Kaleem Ullah, M.; Rafique, Asia; Wang, Baoyuan; Zhu, Bin

    2018-01-01

    Co-doped ceramic electrolytes M0.1Sm0.1Ce0.8O2-δ (M = Ba, Ca, Mg, and Sr) were synthesized via co-precipitation. The focus of this study was to highlight the effects of alkaline earth metals in doped ceria on the microstructure, densification, conductivity, and performance. The ionic conductivity comparisons of prepared electrolytes in the air atmosphere were studied. It has been observed that Ca0.1Sm0.1Ce0.8O2-δ shows the highest conductivity of 0.124 Scm-1 at 650 °C and a lower activation energy of 0.48 eV. The cell shows a maximum power density of 630 mW cm-2 at 650 °C using hydrogen fuel. The enhancement in conductivity and performance was due to increasing the oxygen vacancies in the ceria lattice with the increasing dopant concentration. The bandgap was calculated from UV-Vis data, which shows a red shift when compared with pure ceria. The average crystallite size is in the range of 37-49 nm. DFT was used to analyze the co-doping structure, and the calculated lattice parameter was compared with the experimental lattice parameter.

  12. Determination of oxygen in ternary uranium oxides by a gravimetric alkaline earth addition method

    International Nuclear Information System (INIS)

    Fujino, T.; Tagawa, H.

    1979-01-01

    The applicability of a gravimetric method based on alkaline earth metal addition for the determination of oxygen in ternary uranium oxides of the tupe M-U-O (M=La, Ce and Th) is described. The oxide sample is mixed with MgO or Basub(2.8)UOsub(5.8) and heated in air under suitable conditions. Because uranium is completely oxidized to the hexavalent state during the reaction, oxygen can be determined from the weight change. Oxygen in Lasub(y)Usub(1-y)Osub(2+x) is determined up to y = 0.8 with a standard deviation for x of +- 0.006 with MgO. For Thsub(y)Usub(1-y)Osub(2+x) the value of x is determined with Basub(2.8)UOsub(5.8) with a standard deviation of +- 0.01 at y = 0.8. For Cesub(y)Usub(1-y)Osub(2+x), the method can be applied only for low cerium concentrations where y = 0-0.2; the value for x with Basub(2.8)UOsub(5.8) at y = 0.2 showed a standard deviation of +- 0.002. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

    1978-02-01

    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 H/sub 298/-H/sub 0/, entropy S/sub 298/, heat formation ..delta..Hsub(f,298 ), free energy formation ..delta..Gsub(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.

  14. Photoluminescence properties of Er{sup 3+}-doped alkaline earth titanium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, D.V.R.; Babu, A. Mohan [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jamalaiah, B.C. [Department of Physics, Sree Vidyanikethan Engineering College, Tirupati, 517 102 (India); Moorthy, L. Rama, E-mail: lrmphysics@yahoo.co.i [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jayasimhadri, M.; Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung Soo [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)

    2010-02-18

    Er{sup 3+}-doped alkaline earth titanium phosphate (RTP) glasses with molar composition of 24 (NaPO{sub 3}){sub 6} + 30 KH{sub 2}PO{sub 4} + 25 TiO{sub 2} + 20 RCl{sub 2} + 1 Er{sub 2}O{sub 3} were prepared by melt quenching technique. Judd-Ofelt intensity parameters ({Omega}{sub 2,4,6}) were determined from the experimental oscillator strengths (f{sub exp}) of absorption bands. From these parameters spontaneous emission probabilities (A{sub R}), luminescence branching ratios ({beta}{sub R}) and radiative lifetimes ({tau}{sub R}) have been calculated. Visible and near infrared photoluminescence spectra has been recorded by exciting the samples at 380 and 970 nm respectively. An intense broad emission band at 1.53 {mu}m was observed corresponding to {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition. McCumber theory has been applied to determine the emission cross-sections ({sigma}{sub e}) of the {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition using the absorption cross-sections ({sigma}{sub a}). The lifetimes of {sup 4}S{sub 3/2} level were measured for the glasses by exciting the samples at 540 nm wavelength and the quantum efficiencies were also determined.

  15. Partial exchange of the Li+, Na+ and K+ alkaline cations in the HNi(PO4).H2O layered compound

    International Nuclear Information System (INIS)

    Escobal, Jaione; Mesa, Jose; Pizarro, Jose; Bazan, Begona; Arriortua, Maria; Rojo, Teofilo

    2006-01-01

    The exchange of the Li + (1), Na + (2) and K + (3) alkaline cations in the layered HNi(PO 4 ).H 2 O was carried out starting from a methanolic solution containing the Li(OH).H 2 O hydroxide for (1) and the M(OH) (M=Na and K) hydroxides together with the (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O phases for (2) and (3). The compounds are stable until, approximately, 280 o C for (1) and 400 deg. C for phases (2) and (3), respectively. The IR spectra show the bands belonging to the water molecule and the (PO 4 ) 3- oxoanion. The diffuse reflectance spectra indicate the existence of Ni(II), d 8 , cations in slightly distorted octahedral geometry. The calculated Dq and Racah (B and C) parameters have a mean value of Dq=765, B=905 and C=3895cm -1 , respectively, in accordance with the values obtained habitually for this octahedral Ni(II) cation. The study of the exchange process performed by X-ray powder diffraction indicates that the exchange of the Li + cation in the lamellar HNi(PO 4 ).H 2 O phase is the minor rapid reaction, whereas the exchange of the Na + and K + cations needs the presence of the intermediate (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O intercalate in order to obtain the required product with the sodium and potassium ions. The Scanning electronic microscopy (SEM) images show a mean size of particle of 5μm. The Li + exchanged compound exhibits small ionic conductivity (Ωcm -1 is in the 10 -8 -10 -9 range) probably restrained by the methanol solvent. Magnetic measurements carried out from 5K to room temperature indicate antiferromagnetic coupling as the major interaction in the three phases. Notwithstanding the Li and K phases show a weak ferromagnetism at low temperatures

  16. 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.

  17. Theoretical studies of the spin Hamiltonian parameters and local distortions for Cu{sup 2+} in alkaline earth lead zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo-Kun; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian [University of Electronic Science and Technology of China, Chengdu (China). School of Yingcai Honors; Wu, Shao-Yi; Teng, Bao-Hua; Wu, Ming-He [University of Electronic Science and Technology of China, Chengdu (China). Dept. of Applied Physics

    2016-11-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu{sup 2+}-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 3d{sup 9} 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 Cu{sup 2+}-O{sup 2-} 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

  18. Alkaline earth metabolism: a model useful in calculating organ burdens, excretion rates and committed effective dose equivalent conversion factors

    International Nuclear Information System (INIS)

    Johnson, J.R.; Myers, R.C.

    1981-01-01

    Two mathematical models of alkaline earth metabolism in man have been developed from the postulates given in ICRP Publication 20. Both models have recycling between the organs and blood included explicitly, and the first one retains the power function used by the ICRP for diminution in mineral bone from being available for resorption by blood. In the second model, this diminution is represented by secondary compartments in mineral bone. Both models give good agreement with the retention functions developed in ICRP Publication 20. The second one has been incorporated into a larger model which includes the lung and G.I. tract. This overall model has been used to calculate organ burdens excretion rates, and committed effective dose equivalent factors for the more important radioisotopes of the alkaline earth elements for inhalation and ingestion exposures. (author)

  19. Selenium Sequestration in a Cationic Layered Rare Earth Hydroxide: A Combined Batch Experiments and EXAFS Investigation.

    Science.gov (United States)

    Zhu, Lin; Zhang, Linjuan; Li, Jie; Zhang, Duo; Chen, Lanhua; Sheng, Daopeng; Yang, Shitong; Xiao, Chengliang; Wang, Jianqiang; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

    2017-08-01

    Selenium is of great concern owing to its acutely toxic characteristic at elevated dosage and the long-term radiotoxicity of 79 Se. The contents of selenium in industrial wastewater, agricultural runoff, and drinking water have to be constrained to a value of 50 μg/L as the maximum concentration limit. We reported here the selenium uptake using a structurally well-defined cationic layered rare earth hydroxide, Y 2 (OH) 5 Cl·1.5H 2 O. The sorption kinetics, isotherms, selectivity, and desorption of selenite and selenate on Y 2 (OH) 5 Cl·1.5H 2 O at pH 7 and 8.5 were systematically investigated using a batch method. The maximum sorption capacities of selenite and selenate are 207 and 124 mg/g, respectively, both representing the new records among those of inorganic sorbents. In the low concentration region, Y 2 (OH) 5 Cl·1.5H 2 O is able to almost completely remove selenium from aqueous solution even in the presence of competitive anions such as NO 3 - , Cl - , CO 3 2- , SO 4 2- , and HPO 4 2- . The resulting concentration of selenium is below 10 μg/L, well meeting the strictest criterion for the drinking water. The selenate on loaded samples could be desorbed by rinsing with concentrated noncomplexing NaCl solutions whereas complexing ligands have to be employed to elute selenite for the material regeneration. After desorption, Y 2 (OH) 5 Cl·1.5H 2 O could be reused to remove selenate and selenite. In addition, the sorption mechanism was unraveled by the combination of EDS, FT-IR, Raman, PXRD, and EXAFS techniques. Specifically, the selenate ions were exchanged with chloride ions in the interlayer space, forming outer-sphere complexes. In comparison, besides anion exchange mechanism, the selenite ions were directly bound to the Y 3+ center in the positively charged layer of [Y 2 (OH) 5 (H 2 O)] + through strong bidentate binuclear inner-sphere complexation, consistent with the observation of the higher uptake of selenite over selenate. The results presented in

  20. Extraction process of U from its ores using solutions of alkaline earth carbonates and bicarbonates in presence of carbon dioxide

    International Nuclear Information System (INIS)

    Floreancig, Antoine; Schuffenecker, Robert.

    1976-01-01

    A process is described for extracting uranium from its ores, either directly in the ore deposit or after such ore bodies have been taken from the ground, comprising an oxidation-leaching stage followed by a recovery stage. The characteristic of this process is that in the leaching process, carbonate and bicarbonate solutions of an alkaline-earth metal are used under a pressure of carbon dioxide between zero and 60 bars and at a temperature of zero to 100 0 C [fr

  1. Study of radioactive sources accumulation with application of thermoluminescence dosemeters on the base of alkaline earth metals sulfates

    International Nuclear Information System (INIS)

    Tokbergenov, I.; Sadykov, T.

    2001-01-01

    Methodic for study of accumulation and distribution of radioactive sources in a nature objects is developed. An essence of the method consists of in that quantity of accumulated radioactive sources in a nature objects is defining by absorption dose measured with help of thermoluminescent dosemeters on the base of alkaline earth metals sulfates such as CaSO 4 :Dy and SrSO 4 :Eu

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

    International Nuclear Information System (INIS)

    Diaz-Torrejon, C.C.; Kaplan, Ilya G.

    2011-01-01

    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 4 , Mg 4 , and Ca 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 b /N in Be 3 is 7 times larger and in Be 4 is 18.4 times larger than in Be 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: → 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 Be 4 , Mg 4 , and Ca 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

  3. Are concentrations of alkaline earth elements in maternal hair associated with risk of neural tube defects?

    Science.gov (United States)

    Li, Zhenjiang; Wang, Bin; Huo, Wenhua; Liu, Yingying; Zhu, Yibing; Xie, Jing; Li, Zhiwen; Ren, Aiguo

    2017-12-31

    The relationship between maternal intake of alkaline earth elements (AEEs) during the period of neural tube closure and the risk of neural tube defects (NTDs) is still unclear. We propose that AEE deficiency during the early period of pregnancy is associated with an elevated risk of NTDs in the offspring. In this study, we recruited 191 women with NTD-affected pregnancies (cases) and 261 women who delivered healthy infants (controls). The concentrations of four AEEs (Ca, Mg, Sr, Ba) in maternal hair sections that grew during early pregnancy were analyzed. Information on the dietary habits of the mothers was also collected by questionnaire. Higher concentrations of the four AEEs in hair had protective effects against the risk of total NTDs, with odds ratios with 95% confidence interval (comparing groups separated by each median level) of 0.44 (0.28-0.68) for Mg, 0.56 (0.36-0.87) for Ca, 0.45 (0.28-0.70) for Sr, and 0.41 (0.26-0.65) for Ba. Significant negative dose-response trends were identified for the relationships between the four AEE concentrations in maternal hair and the risks of anencephaly and spina bifida, but not for encephalocele. The frequencies of maternal consumption of fresh green vegetables, fresh fruit, and meat or fish were positively correlated with the concentrations of AEEs in hair. We concluded that the maternal intake of AEEs may play an important role in preventing NTD formation in offspring, and that this intake is related to maternal dietary habits of consuming fresh green vegetables, fresh fruit, and fish or meat. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms

    Science.gov (United States)

    Kanász-Nagy, Márton; Ashida, Yuto; Shi, Tao; Moca, Cǎtǎlin Paşcu; Ikeda, Tatsuhiko N.; Fölling, Simon; Cirac, J. Ignacio; Zaránd, Gergely; Demler, Eugene A.

    2018-04-01

    We propose a scheme to realize the Kondo model with tunable anisotropy using alkaline-earth atoms in an optical lattice. The new feature of our setup is Floquet engineering of interactions using time-dependent Zeeman shifts, that can be realized either using state-dependent optical Stark shifts or magnetic fields. The properties of the resulting Kondo model strongly depend on the anisotropy of the ferromagnetic interactions. In particular, easy-plane couplings give rise to Kondo singlet formation even though microscopic interactions are all ferromagnetic. We discuss both equilibrium and dynamical properties of the system that can be measured with ultracold atoms, including the impurity spin susceptibility, the impurity spin relaxation rate, as well as the equilibrium and dynamical spin correlations between the impurity and the ferromagnetic bath atoms. We analyze the nonequilibrium time evolution of the system using a variational non-Gaussian approach, which allows us to explore coherent dynamics over both short and long timescales, as set by the bandwidth and the Kondo singlet formation, respectively. In the quench-type experiments, when the Kondo interaction is suddenly switched on, we find that real-time dynamics shows crossovers reminiscent of poor man's renormalization group flow used to describe equilibrium systems. For bare easy-plane ferromagnetic couplings, this allows us to follow the formation of the Kondo screening cloud as the dynamics crosses over from ferromagnetic to antiferromagnetic behavior. On the other side of the phase diagram, our scheme makes it possible to measure quantum corrections to the well-known Korringa law describing the temperature dependence of the impurity spin relaxation rate. Theoretical results discussed in our paper can be measured using currently available experimental techniques.

  5. 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.

  6. Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

    International Nuclear Information System (INIS)

    Zhang, Sheng; Qu, Xiao-Ni; Xie, Gang; Wei, Qing; Chen, San-Ping

    2014-01-01

    Four alkaline-earth coordination polymers, [Ba(Pzdc)(H 2 O)] n (1), [Ba(Pzdc)] n (2), [AgSr(Pzdc)(NO 3 )(H 2 O)] n (3), [Ag 2 Ca(Pzdc) 2 (H 2 O)] n (4) (H 2 Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba 2 O 11 N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H 2 O)] n (1), [Ba(Pzdc)] n (2), [AgSr(Pzdc)(NO 3 )(H 2 O)] n (3), [Ag 2 Ca(Pzdc) 2 (H 2 O)] n (4) (H 2 Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2

  7. Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Sheng; Qu, Xiao-Ni; Xie, Gang; Wei, Qing; Chen, San-Ping, E-mail: sanpingchen@126.com

    2014-02-15

    Four alkaline-earth coordination polymers, [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba{sub 2}O{sub 11}N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2.

  8. Study of the alkaline cations complexation by photo-isomerizable calixarenes; Etude de la complexation de cations alcalins par des calixarenes photoisomerisables

    Energy Technology Data Exchange (ETDEWEB)

    Reynier, N.

    1996-04-25

    The first step to reduce the volume and the toxicity of radioactive waste coming from the spent fuel reprocessing is to separate long life radioisotopes from others ones with a shorter period. The aim of this study is to show that the control of the two phenomenons, complexation of the cation by the calixarenes and its de-complexation, can be envisaged by the introduction on the molecule of a chromophore group, azo benzene, able to modify the complexing site structure of the calixarenes with an isomerization trans-cis induced by ultraviolet radiation, and isomerization cis-trans thermally induced by a visible radiation. (N.C.). 112 refs., 78 figs., 23 tabs.

  9. A gravimetric method for the determination of oxygen in uranium oxides and ternary uranium oxides by addition of alkaline earth compounds

    International Nuclear Information System (INIS)

    Fujino, Takeo; Tagawa, Hiroaki; Adachi, Takeo; Hashitani, Hiroshi

    1978-01-01

    A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800-1100 0 C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UOsub(2+x) test sample is +-0.0008-0.001, if a correction is applied for atmospheric moisture absorbed during mixing. (Auth.)

  10. Rare earth sulfates

    International Nuclear Information System (INIS)

    Komissarova, L.N.; Shatskij, V.M.; Pokrovskij, A.N.; Chizhov, S.M.; Bal'kina, T.I.; Suponitskij, Yu.L.

    1986-01-01

    Results of experimental works on the study of synthesis conditions, structure and physico-chemical properties of rare earth, scandium and yttrium sulfates, have been generalized. Phase diagrams of solubility and fusibility, thermodynamic and crystallochemical characteristics, thermal stability of hydrates and anhydrous sulfates of rare earths, including normal, double (with cations of alkali and alkaline-earth metals), ternary and anion-mixed sulfates of rare earths, as well as their adducts, are considered. The state of ions of rare earths, scandium and yttrium in aqueous sulfuric acid solutions is discussed. Data on the use of rare earth sulfates are given

  11. Theoretical consideration of metabolic and histomorphometric data for alkaline earth and actinide distribution dynamics in the beagle skeleton

    International Nuclear Information System (INIS)

    Parks, N.J.

    1989-01-01

    The beagle has been used for thirty years as a putative model for human skeletal dynamics in terms of metabolic behaviour and response to in situ radiation insults. The partitioned clearance model (PCM) is a bone by bone description of radionuclide redistribution in the beagle skeleton after the end of exposure to 226 Ra by eight semi-monthly injections at 435-535 days or by continuous ingestion of 90 Sr from in utero to 540 days. The PCM describes both the clearance of radium after deposition on surfaces following injection and the clearance of 90 Sr after uniform deposition in the skeleton as a function of Ca mass. The PCM relates the metabolically determined time-zero deposition fraction (% A) per skeletal component to the calcium fraction (%Ca) per component. The ratio of these two fractions is defined as an estimator of relative 'surface',S, in PCM for the alkaline earths (ae). A comparison is made of 'surface' as defined, in PCM, by activity fraction per mass fraction in a given skeletal component for bone seeking alkaline earths (S ae ), to similarly defined 'surface' (S act ) for injected plutonium citrate. For inhaled soluble plutonium nitrate that translocates to bone, the S act values are very similar to the S ae values for injected radium. The physiochemical determinants of Pu deposition in bone after inhalation appear to be similar to those for alkaline earths. Histomorphometric data from actual bone surfaces marked in vivo with fluorescent labels given to a juvenile dog and then 13 years later give direct evidence that actinides not removed metabolically may never be removed by remodelling processes. (author)

  12. Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

    Science.gov (United States)

    Chen, S.G.; Yang, R.T.

    1997-01-01

    From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

  13. Study of polyoxide catalysts of methane combustion on Mn, Cu, Ni, rare earth elements, alkaline earth elements base by the X-ray fluorescence analysis method

    International Nuclear Information System (INIS)

    Grigor'eva, V.P.; Popova, N.M.; Zheksenbaeva, Z.T.; Sass, A.S.; Salakhova, R.Kh.; Dosumov, K.D.

    2002-01-01

    The results of X-ray fluorescence analysis of polyoxide catalysts on of Mn, Cu, Ni, rare earth elements, alkaline earth elements base supported on 2 % Ce/θ-Al 2 O 3 are presented. This polyoxide catalysts are using for deep methane oxidation. DRON-4-7 X-ray diffractometers was applied for the analysis. It was found, that oxides in Ni-Cu-Cr catalysts after long time heating up to 1200 deg. C have been interacted with catalyst supports with Ni(Cu)Al 2 O 3 aluminates formation and due to its decomposition transformation degree of CH 4 to CO 2 are reduced. Activity of MnBaSrCeLa catalysts after heating up to 1200 deg. C does not changed

  14. 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)

    Grahek, Z.; Kosutic, K.; Lulic, S.; Kvastek, K.; Eskinja, I.

    1999-01-01

    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 NH 4 NO 3 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 HNO 3 in methanol 3 in ethanol 3 in 1-propanol for each individual ion, as well as in the Ca 3 in methanol, 0.25M HNO 3 in ethanol and 0.25M HNO 3 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

  15. Effect of cation size and disorder on the properties of the rare earth ...

    Indian Academy of Sciences (India)

    Administrator

    5CoO3 increases with the average size of the A-site cation up to an 〈rA〉of 1·40 Å and decreases thereafter due to size mismatch. Disorder due to size mismatch has been investigated by studying the properties of two series of cobaltates with ...

  16. Environmental Characteristics of Carbonatite and Alkaline Intrusion-related Rare Earth Element (REE) Deposits

    Science.gov (United States)

    Seal, R. R., II; Piatak, N. M.

    2017-12-01

    Carbonatites and alkaline intrusions are important sources of REEs. Environmental risks related to these deposit types have been assessed through literature review and evaluation of the geochemical properties of representative samples of mill tailings and their leachates. The main ore mineral in carbonatite deposits is bastnasite [(Ce,La)(CO3)F], which is found with dolomite and calcite ( 65 %), barite (20 - 25 %), plus a number of minor accessory minerals including sulfides such as galena and pyrite. Generally, alkaline intrusion-related REE deposits either occur in layered complexes or with dikes and veins cutting alkaline intrusions. Such intrusions have a more diverse group of REE ore minerals that include fluorcarbonates, oxides, silicates, and phosphates. Ore also can include minor calcite and iron (Fe), lead (Pb), and zinc (Zn) sulfides. The acid-generating potential of both deposit types is low because of a predominance of carbonate minerals in the carbonatite deposits, the presence of feldspars and minor calcite in alkaline intrusion-related deposits, and to only minor to trace occurrence of potentially acid-generating sulfide minerals. Both deposit types, however, are produced by igneous and hydrothermal processes that enrich high-field strength, incompatible elements, which typically are excluded from common rock-forming minerals. Elements such as yttrium (Y), niobium Nb), zirconium (Zr), hafnium (Hf), tungsten (W), titanium (Ti), tantalum (Ta), scandium (Sc), thorium (Th), and uranium (U) can be characteristic of these deposits and may be of environmental concern. Most of these elements, including the REEs, but with the exception of U, have low solubilities in water at the near-neutral pH values expected around these deposits. Mill tailings from carbonatite deposits can exceed residential soil and sediment criteria for Pb, and leachates from mill tailings can exceed drinking water guidelines for Pb. The greatest environmental challenges, however, are

  17. 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.

  18. Evaluation of complexing agents and column temperature in ion chromatographic separation of alkali metals, alkaline earth metals and transition metals ion

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Pandey, Ashish; Name, Anil B.; Das, D.K.; Behere, P.G.; Mohd Afzal

    2015-01-01

    The aim of ion chromatography method development is the resolution of all metal ions of interests. Resolution can be improved by changing the selectivity. Selectivity in chromatography can be altered by changes in mobile phase (eg eluent type, eluent strength) or through changes in stationary phase. Temperature has been used in altering the selectivity of particularly in reversed phase liquid chromatography and ion exchange chromatography. Present paper describe the retention behaviour of alkali metals, alkaline earth metals and transition metal ions on a silica based carboxylate function group containing analyte column. Alkali metals, alkaline earth metals and transition metal ions were detected by ion conductivity and UV-VIS detectors respectively

  19. Distribution behavior of uranium, neptunium, rare-earth elements (Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiCl-KCl eutectic salt and liquid cadmium or bismuth

    International Nuclear Information System (INIS)

    Kurata, M.; Sakamura, Y.; Hijikata, T.; Kinoshita, K.

    1995-01-01

    Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCl eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl/Bi system were by one or two orders of magnitude larger than those in the LiCl-KCl/Cd system. On the contrary, the separation factors of alkaline-earth metals and divalent rare-earth elements to trivalent rare-earth elements were by one or two orders of magnitude smaller in the LiCl-KCl/Bi system. (orig.)

  20. Studies on the adsorption behaviour of heavy rare earths with a strong cation exchanger DOWEX 50W-2X8

    International Nuclear Information System (INIS)

    Vijayalakshmi, R.; Singh, D.K.; Anitha, M.; Kotekar, M.K.; Dasgupta, K.; Singh, H.

    2014-01-01

    Rare earths have been a very fascinating area of research since long due to its wide applicability's in many field including superconductors, lasers, phosphors, medical, electronics, magnet, optics etc. Separation of rare earths is a challenging task and over the years many separation schemes based on solvent extraction, ion exchange, membrane etc have been developed and deployed. In the present work, we have investigated the adsorption behavior of heavy rare earths from a crude concentrate analyzing ∼ 80% Y 2 O 3 , ∼12% Dy 2 O 3 , ∼4% Er 2 O 3 etc., with a strong cationic exchanger namely Dowex 50W-2X8 in order to separate them in pure form. To start with, Y was selected as a representative of heavy rare earths and the conditions were optimized in batch experiments and later were applied to the feed solution containing Dy, Er, Ho etc. in a column study. Effects of experimental variables such as contact time, pH, weight of resin, concentration of the feed metal, temperature, desorption agents, on adsorption of Y was studied

  1. Structural studies of Langmuir-Blodgett films containing rare-earth metal cations

    DEFF Research Database (Denmark)

    Khomutov, G.B.; Antipina, M.N.; Bykov, I.V.

    2002-01-01

    Comparative structural study of gadolinium stearate Langmuir-Blodgett (LB) films formed by monolayer deposition from either aqueous gadolinium acetate or gadolinium chloride solutions have been carried out. Structure of the films was characterized by X-ray diffraction, Fourier transform infrared...... spectroscopy, high-energy electron diffraction, atomic force microscopy and scanning electron microscopy. It was found that when subphase pH had a value at which all monolayer stearic acid molecules were ionized and bound with Gd3+ cations (pH > 5), the LB films deposited from gadolinium acetate and gadolinium....... The data obtained indicate that the control of multivalent metal cations complexes formation in the subphase and at the monolayer surface can be an instrument for optimization, the conditions to form metal-containing LB film with regulated structure and properties....

  2. Predictibility of the stability constant of a radium-cryptate by means of in vivo data from radioactive alkaline earthes.

    Science.gov (United States)

    Müller, W H

    1977-08-01

    By means of a formula, developed by J. Schubert[9] and A. Catsch, H.J. Heller[3] as well as a relation postulated by A. Catsch[1] the "thermodynamic" stability constant of the Radium (222)-cryptate (KRaRa(222) was calculated from measurements of the total body retention of the total body retention of the radioactive alkaline earthes 85SR, 140Ba and 224Ra and its (222)-cryptates in rats [5-7]. From the same in vivo data a direct lineary relationship between the log of the effectiveness quotient, log EQM(222), and the log of the "thermodynamic" stability log KMM(222) was found graphically. The values from the graph correspond with those of the calculation.

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

    International Nuclear Information System (INIS)

    Mitroy, J.; Bromley, M.W.J.

    2003-01-01

    The van der Waals coefficients, C 6 , C 8 , and C 10 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, D 8 and the three-body coefficient, C 9 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

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

    International Nuclear Information System (INIS)

    Mitroy, J.; Bromley, M.W.J.

    2003-01-01

    The van der Waals coefficients C 6 , C 8 , and C 10 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 C 6 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)

  5. Effect of alkaline earth metal doping on thermal, optical, magnetic and dielectric properties of BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Bhushan, B; Das, D; Basumallick, A; Bandopadhyay, S K; Vasanthacharya, N Y

    2009-01-01

    Substrate-free pure-phase BiFeO 3 (BFO) nanoparticles doped with alkaline earth metals (Ba, Sr and Ca) have been synthesized by a sol-gel route and their thermal, optical, dielectric and magnetic properties are discussed. The characteristic structural phase transitions of BFO nanoparticles are found to occur at much lower temperatures. A reduction of the Neel temperature has been observed in the doped samples in comparison with the pristine one, whereas the band gap shows a reverse trend. Iron was found to be only in the Fe 3+ valence state in all the doped samples. Magnetoelectric coupling is seen in our samples. Weak ferromagnetism is observed at room temperature in all of the doped and undoped BFO nanoparticles with the largest value of coercive field ∼1.78 kOe and saturation magnetization ∼2.38 emu g -1 for Ba and Ca doped BFO nanoparticles, respectively.

  6. 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.

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

    Science.gov (United States)

    Parker, David; Singh, David J

    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 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. PMID:27877610

  8. Quantum mechanical study of molecular collisions at ultra-low energy: applications to alkali and alkaline-earth systems

    International Nuclear Information System (INIS)

    Quemener, G.

    2006-10-01

    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)

  9. Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts

    Science.gov (United States)

    Zhu, Ming; Ma, Hongfang; Wang, Mingjing; Wang, Zhihua; Sharif, Adel

    2016-04-01

    Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

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

    International Nuclear Information System (INIS)

    Xu, Shuang; Kan, Kan; Yang, Ying; Jiang, Chao; Gao, Jun; Jing, Liqiang; Shen, Peikang; Li, Li

    2015-01-01

    Highlights: • The small-sized SnO 2 (5–7 nm) were obtained by adding the alkaline-earth. • Sr-composited SnO 2 nanofibers showed uniform nanotubes structure (Sr/SnO 2 ). • Sr/SnO 2 showed an excellent sensing performance to NH 3 at room temperature. - Abstract: One-dimensional alkaline-earth metals composited SnO 2 (Ae/SnO 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 2 was 5–7 nm, which was smaller than the pristine SnO 2 nanorods attached by 20 nm nanoparticles. Moreover, Sr/SnO 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 2 nanotubes exhibited an excellent sensing response toward NH 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 2 nanorods. The enhanced sensor performances were attributed to the higher conductivity of the Sr/SnO 2 . Mott–Schottky plots (M–S) and electrochemical impedance spectroscopy (EIS) measurements indicated that the carrier density of Sr/SnO 2 nanotubes was 3 fold of that pristine SnO 2

  11. Coprecipitation of rare earths in systems of three heterovalent ions with sulfates of alkali and alkaline-earth metals

    International Nuclear Information System (INIS)

    Bobrik, V.M.

    1977-01-01

    Co-precipitation of rare earth elements (REE) in milligram amounts (3x10 -3 -3x10 -1 M) with alkali earth (AEE) sulfates in presence of alkali metal ions has been studied, the AEE:REE ratios between the co-precipitator and a REE (up to 50:1) the latter can be co-precipitated quantitatively in presence of corresponding alkali metals linked with the AEE in the Periodic table by a diagonal, i.e. in presence of sodium in co-precipitation with calcium sulfate, potassium with strontium sulfate and rubidium with barium sulfate. Co-precipitation with sulfates of sodium and calcium occurs at temperatures above 85 deg C and presumably involves calcium semihydrate. In presence of an alkali metal REE co-precipitation with AEE becomes isomorphic, i.e. at different AEE:REE ratios the co-precipitation coefficient remains constant. In presence of corresponding alkali metals the decrease in effectiveness of co-precipitation with AEE in the La-Lu series is more pronounced

  12. Cure and mechanical properties of carboxylated nitrile rubber (XNBR) vulcanized by alkaline earth metal compounds

    Science.gov (United States)

    Tulyapitak, Tulyapong

    Compounds of carboxylated nitrile rubber (XNBR) with alkaline metal oxides and hydroxide were prepared, and their cure and mechanical properties were investigated. Magnesium oxide (MgO) with different specific surface areas (45, 65, and 140 m2/g) was used. Increased specific surface area and concentration of MgO resulted in higher cure rate. Optimum stiffness, tensile strength, and ultimate strain required an equimolar amount of acidity and MgO. The effect of specific surface area on tensile properties was not significant. Crosslink density of XNBR-MgO vulcanizates increased with increased amounts of MgO. ATR-IR spectroscopy showed that neutralization occurs in two steps: (1) During mixing and storage, MgO reacts with carboxyl groups (RCOOH) to give RCOOMgOH. (2) Upon curing, these react bimolecularly to form RCOOMgOOCR and Mg(OH)2. Dynamic mechanical thermal analysis revealed an ionic transition at higher temperature, in addition to the glass transition. The ionic transition shifts to higher temperature with increasing MgO concentration. Like MgO-XNBR systems, cure rates of XNBR-calcium hydroxide (Ca(OH)2) and XNBR-barium oxide (BaO) compounds increased with increased content of curing agents. Curing by these two agents resulted in ionic crosslinks. To ensure optimum tensile properties, equimolar amounts of carboxyl groups and curing agents were required. Dynamic mechanical analysis revealed the ionic transition in these two systems. It shifted to higher temperature with increased amounts of curing agents. In contrast to MgO, Ca(OH)2, and BaO, calcium oxide (CaO) gave results similar to those for thermally cured samples. No ionic transition was observed in XNBR-CaO systems. Tensile strength of XNBR depended on the strength of ionic crosslinks, which was dependent on the size of the alkaline metal ions.

  13. Cationized dextran nanoparticle-encapsulated CXCR4-siRNA enhanced correlation between CXCR4 expression and serum alkaline phosphatase in a mouse model of colorectal cancer

    Directory of Open Access Journals (Sweden)

    Abedini F

    2012-07-01

    Full Text Available Fatemeh Abedini,1 Hossein Hosseinkhani,2 Maznah Ismail,1,3 Abraham J Domb,4 Abdul Rahman Omar,1,5 Pei Pei Chong,1,2 Po-Da Hong,3 Dah-Shyong Yu,6 Ira-Yudovin Farber41Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, Selangor, 2Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, 3Faculty of Medicine & Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia, 4Institute of Drug Research, The Center for Nanoscience and Nanotechnology, School of Pharmacy-Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel, 5Faculty of Veterinary Medicine, Universiti Putra Malaysia, Selangor, Malaysia, 6Nanomedicine Research Center, National Defense Medical Center, Taipei, TaiwanPurpose: The failure of colorectal cancer treatments is partly due to overexpression of CXCR4 by tumor cells, which plays a critical role in cell metastasis. Moreover, serum alkaline phosphatase (ALP levels are frequently elevated in patients with metastatic colorectal cancer. A polysaccharide, dextran, was chosen as the vector of siRNA. Spermine was conjugated to oxidized dextran by reductive amination process to obtain cationized dextran, so-called dextran-spermine, in order to prepare CXCR4-siRNAs/dextran-spermine nanoparticles. The fabricated nanoparticles were used in order to investigate whether downregulation of CXCR4 expression could affect serum ALP in mouse models of colorectal cancer.Methods: Colorectal cancer was established in BALB/C mice following injection of mouse colon carcinoma cells CT.26WT through the tail vein. CXCR4 siRNA for two sites of the target gene was administered following injection of naked siRNA or siRNA encapsulated into nanoparticles.Results: In vivo animal data revealed that CXCR4 silencing by dextran-spermine nanoparticles significantly downregulated CXCR4 expression compared with naked CXCR4 siRNA. Furthermore, there was

  14. Iron oxides, divalent cations, silica, and the early earth phosphorus crisis

    DEFF Research Database (Denmark)

    Jones, C.; Nomosatryo, S.; Crowe, S.A.

    2015-01-01

    As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry...... that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus...... waters shifted from phosphorus to iron limiting....

  15. Passive behavior of magnesium alloys (Mg-Zr) containing rare-earth elements in alkaline media

    International Nuclear Information System (INIS)

    Pinto, R.; Ferreira, M.G.S.; Carmezim, M.J.; Montemor, M.F.

    2010-01-01

    The passive behavior of magnesium alloys ZK31, EZ33 and WE54 was studied in alkaline media (NaOH - pH 13) in the presence and absence of chloride ions. The electrochemical properties were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and capacitance measurements. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the study of the chemical composition and surface morphology of the surface films, respectively. The electrochemical impedance results revealed that the film formed on the surface of the three alloys is characterized by an increasing resistance, which stabilized with time. In the absence of chloride the film resistance was identical for all the three alloys. However, in the presence of chloride, the resistance of the film formed on the EZ33 alloy dropped nearly one order of magnitude comparatively to the other alloys. Generally, in the presence of chloride there was a decrease of the conductive character of the film. The films are homogeneous and, according to the XPS results, the outer layer seemed mainly composed of Mg(OH) 2 and the internal layer composed of MgO, independently of the presence of chloride. The AFM study revealed that the presence of chloride affected film morphology, namely nano-crystallites dimensions and aggregates size that increased.

  16. TL process in europium doped alkaline earth sulphate phosphors- a review

    International Nuclear Information System (INIS)

    Bhatt, B.C.

    2003-01-01

    CaSO 4 doped with the rare earth (RE) ion dysprosium or thulium is used routinely as a thermoluminescent dosimeter (TLD) to monitor personal exposure to x- and γ-radiation. The CaSO 4 :Eu phosphor is potentially important for radio photoluminescence (RPL) and ultraviolet (UV) dosimetry. Eu 3+ → Eu 2+ conversion is suggested to play a pivotal role in UV and γ-ray induced thermoluminescence. However, there is disagreement among different workers on the mechanism of gamma and UV induced TL in this phosphor system. This paper will review the work reported on CaSO 4 :Eu and make effects to project overall picture on this phosphor system. (author)

  17. Rare earth elements leaching from Tin slag using Acid Chloride after Alkaline fusion process

    International Nuclear Information System (INIS)

    Kurnia Trinopiawan; Budi Yuli Ani; June Mellawati; Mohammad Zaki Mubarok

    2016-01-01

    Tin slag, a waste product from tin smelting process, has a potency to be utilized further by extracting the valuable metals inside, such as rare earth elements(REE). The objective of this study is to determine the optimum leaching condition of REE from tin slag after alkali fusion. Silica structure in slag is causing the direct leaching uneffectively. Therefore, pre-treatment step using alkali fusion is required to break the structure of silica and to increase the porosity of slag. Fusion is conducted in 2 hours at 700°C, with ratio of natrium hydroxide (NaOH) : slag = 2 : 1. Later, frit which is leached by water then leached by chloride acid to dissolve REE. As much as 87,5% of REE is dissolved at 2 M on chloride acid (HCl) concentration, in 40°C temperature, -325 mesh particle size, 15 g/100 ml of S/L, 150 rpm of agitation speed, and 5 minutes of leaching time. (author)

  18. Rare Earth Elements (REE Deposits Associated with Great Plain Margin Deposits (Alkaline-Related, Southwestern United States and Eastern Mexico

    Directory of Open Access Journals (Sweden)

    Virginia T. McLemore

    2018-01-01

    Full Text Available W.G. Lindgren in 1933 first noted that a belt of alkaline-igneous rocks extends along the eastern edge of the Rocky Mountains and Basin and Range provinces from Alaska and British Columbia southward into New Mexico, Trans-Pecos Texas, and eastern Mexico and that these rocks contain relatively large quantities of important commodities such as, gold, fluorine, zirconium, rare earth elements (REE, tellurium, gallium, and other critical elements. In New Mexico, these deposits were called Great Plain Margin (GPM deposits, because this north-south belt of alkaline-igneous rocks roughly coincides with crustal thickening along the margin between the Great Plains physiographic province with the Basin and Range (including the Rio Grande rift and Rocky Mountains physiographic provinces, which extends into Trans-Pecos Texas and eastern Mexico. Since 1996, only minor exploration and development of these deposits in New Mexico, Texas, and eastern Mexico has occurred because of low commodity prices, permitting issues, and environmental concerns. However, as the current demand for gold and critical elements, such as REE and tellurium has increased, new exploration programs have encouraged additional research on the geology of these deposits. The lack of abundant quartz in these systems results in these deposits being less resistant to erosion, being covered, and not as well exposed as other types of quartz-rich deposits, therefore additional undiscovered alkaline-related gold and REE deposits are likely in these areas. Deposits of Th-REE-fluorite (±U, Nb epithermal veins and breccias are found in the several GPM districts, but typically do not contain significant gold, although trace amounts of gold are found in most GPM districts. Gold-rich deposits in these districts tend to have moderate to low REE and anomalously high tungsten and sporadic amounts of tellurium. Carbonatites are only found in New Mexico and Mexico. The diversity of igneous rocks, including

  19. Luminescence investigation of R{sup 3+}-doped alkaline earth tungstates prepared by a soft chemistry method

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Helliomar P. [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil); Kai, Jiang [Pontifícia Universidade Católica do Rio de Janeiro, Departamento de Química, Rio de Janeiro, RJ, Brazil (Brazil); Silva, Ivan G.N.; Rodrigues, Lucas C.V. [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil); Felinto, Maria C.F.C. [Centro de Química e Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares, São Paulo, SP (Brazil); Hölsä, Jorma [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil); Department of Chemistry, University of Turku,FI-20014 Turku (Finland); Turku University Centre for Materials and Surfaces (MatSurf), Turku (Finland); Malta, Oscar L. [Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, PE (Brazil); Brito, Hermi F., E-mail: hefbrito@iq.usp.br [Instituto de Química, Universidade de São Paulo, São Paulo, SP (Brazil)

    2016-02-15

    Highly luminescent rare earth (R{sup 3+}) doped alkaline-earth tungstates MWO{sub 4}:R{sup 3+} (M{sup 2+}: Ca, Sr and Ba, R{sup 3+}: Eu, Tb, Gd) were prepared with a room temperature coprecipitation method. The phosphors were characterized by X-ray powder diffraction (XPD), thermal analysis (TG), infrared absorption spectroscopy (FTIR) and UV excited photoluminescence. The as-prepared MWO{sub 4}:R{sup 3+} particles belong to the tetragonal scheelite phase, and are well crystallized and are of the average size of 16–48 nm. The excitation and emission spectra of the materials were recorded at 300 and 77 K temperatures. The luminescent materials exhibit intense red (Eu{sup 3+}) and green (Tb{sup 3+}) colors under UV excitation. The excitation spectra of the Eu{sup 3+} doped materials show broad bands arising from the ligand-to-metal charge transfer transitions (O{sup 2−}→W{sup VI} and O{sup 2−}→Eu{sup 3+}) as well as narrow bands from 4f–4f intraconfigurational transitions of Eu{sup 3+}. 4f–4f emission data of the Eu{sup 3+} and Tb{sup 3+} in the MWO{sub 4} host matrices as well as the values of emission quantum efficiencies of the {sup 5}D{sub 0} level and the 4f–4f experimental intensity parameters of Eu{sup 3+} ion are presented and discussed. - Highlights: • Highly red Europium and green Terbium doped tungstate under UV excitation. • Efficient energy transfer process from tungstate to R{sup 3+} ion. • Promising candidates for a red (Eu{sup 3+}) and green (Tb{sup 3+}) emitting phosphors. • Ligand Metal charge transfer to R{sup 3+} ion. • Charge compensation with Na{sup +}.

  20. Structural, optical absorption and photoluminescence spectral studies of Sm3+ ions in Alkaline-Earth Boro Tellurite glasses

    Science.gov (United States)

    Siva Rama Krishna Reddy, K.; Swapna, K.; Mahamuda, Sk.; Venkateswarlu, M.; Srinivas Prasad, M. V. V. K.; Rao, A. S.; Prakash, G. Vijaya

    2018-05-01

    Sm3+ ions doped Alkaline-Earth Boro Tellurite (AEBT) glasses were prepared by using conventional melt quenching technique and characterized using the spectroscopic techniques such as FT-IR, optical absorption, emission and decay spectral measurements to understand their utility in optoelectronic devices. From absorption spectra, the bonding parameters, nephelauxetic ratios were determined to know the nature of bonding between Sm3+ ions and its surrounding ligands. From the measured oscillator strengths, the Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ions in AEBT glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 in the visible region for which the emission cross-sections and branching ratios were evaluated. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition showed single exponential for lower concentration and non-exponential for higher concentration of doped rare earth ion in the as prepared glasses. Conversion of decay spectral profiles from single to non-exponential have been analyzed using Inokuti-Hirayama (I-H) model to understand the energy transfer mechanism involved in the decay process. CIE Chromaticity coordinates were measured using emission spectral data to identify the exact region of emission from the as-prepared glasses. From the evaluated radiative parameters, emission cross-sections and quantum efficiencies, it was observed that AEBT glass with 1 mol% of Sm3+ ions is more suitable for designing optoelectronic devices.

  1. Transfer of alkaline earth elements in mothers' milk and doses from 45Ca, 90Sr and 226Ra

    International Nuclear Information System (INIS)

    Smith, T.J.; Phipps, A.W.; Fell, T.P.; Harrison, J.D.

    2003-01-01

    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 45 Ca, 90 Sr and 226 Ra 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 45 Ca (ratio = 3.1) while, in other cases such as 90 Sr, the infant dose can be a significant fraction of the adult dose. (author)

  2. Fates and roles of alkali and alkaline earth metal species during the pyrolysis and gasification of a Victorian lignite

    Energy Technology Data Exchange (ETDEWEB)

    Mody, D.; Wu, H.; Li, C. [Monash University, Vic. (Australia). CRC for Clean Power from Lignite, Dept. of Chemical Engineering

    2000-07-01

    The transformation of alkali and alkaline earth metal (AAEM) species in a Victorian lignite during the pyrolysis and subsequent gasification in CO{sub 2} was studied in a novel quartz fluidised-bed reactor. Lignite samples prepared by physically adding NaCl and ion-exchanging Na{sup +} and Ca{sup ++} into the lignite were used to investigate the effects of chemical forms and valency of the AAEM species in the substrate lignite on their transformation during pyrolysis and gasification. Carboxyl-bound Na was found to be less volatile than Na present as NaCl, but more volatile than carboxyl-bound Ca during pyrolysis at temperatures between 400 and 900{sup o}C. However, the carboxyl-bound Na was volatilised to a much greater extent than the carboxyl-bound Ca in the same lignite during pyrolysis. It was seen that the loading of NaCl into the lignite did not significantly affect the char reactivity in the fluidised-bed reactor at 900{sup o}C.

  3. X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes

    Science.gov (United States)

    Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

    1998-01-01

    NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

  4. Hydrogen storage property of alkali and alkaline-earth metal atoms decorated C24 fullerene: A DFT study

    Science.gov (United States)

    Zhang, Yafei; Cheng, Xinlu

    2018-04-01

    The hydrogen storage behavior of alkali and alkaline-earth metal (AM = Li, Na, K, Mg, Ca) atoms decorated C24 fullerene was investigated by using density functional theory (DFT) study. Our results indicate that the AM atoms prefer to adsorb atop the center of tetragon of C24 fullerene with the largest binding energy than other possible adsorption sites. Moreover, the hydrogen storage gravimetric density of 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations reaches up to 12.7 wt%, 10.1 wt% and 12 wt%, higher than the year 2020 target from the US department of energy (DOE). Also, the average adsorption energies of H2 molecules of the 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations are -0.198 eV/H2, -0.164 eV/H2 and -0.138 eV/H2, locate the desirable range under the physical adsorption at near ambient conditions. These findings will have important implications on designing new hydrogen storage materials in the future.

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

    International Nuclear Information System (INIS)

    Bialek, Beata; Lee, Jaeil

    2011-01-01

    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. Radium isotopes, alkaline earth diagenesis, and age determination of travertine from Mammoth Hot Springs, Wyoming, U.S.A

    International Nuclear Information System (INIS)

    Sturchio, N.C.

    1990-01-01

    Travertine from active springs, former vents, and drill core was analyzed for Ra isotopes, other alkaline earth elements, and mineralogical composition. Thermal water also was analyzed. Travertine, presently being deposited, contains 3.0-15.3 pCi/g 226 Ra, and has a 228 Ra/ 226 Ra ratio identical to that in thermal water. Travertine precipitates mostly as aragonite and experiences a complete diagenetic transformation to calcite within 9 a. Systematic compositional changes associated with this diagenetic transformation are enrichment of Mg and depletion of Sr, Ba and Ra. Apparent mineral-water distribution coefficients for Mg, Sr and Ba in aragonite and calcite are within the range of those determined experimentally, implying near-equilibrium conditions and high water-rock ratios during diagenesis. Impure travertine from near the base of a section in the Y-10 drill hole (at 72.9 m depth) has a 230 Th/ 234 U isochron age of 7700±440 a. The content of 226 Ra in the normal, subhorizontally layered, porous travertine decreases with depth. The observed 226 Ra vs depth relation is consistent with continuous deposition of travertine at the site from 7700 a BP to near present at a mean rate of ∼1.0 cm/a, and indicates minimal exchange of Ra between travertine and pore water after the early diagenetic transformation of aragonite to calcite. (author)

  7. Synergetic effect of alkaline earth metal oxides and iron oxides on the degradation of hexachlorobenzene and its degradation pathway.

    Science.gov (United States)

    Su, Guijin; Liu, Yexuan; Huang, Linyan; Shi, Yali; Zhang, Aiqian; Zhang, Lixia; Liu, Wenbin; Gao, Lirong; Zheng, Minghui

    2013-01-01

    The degradation of hexachlorobenzene (HCB) was carried out over physical mixtures of a series of alkaline earth metal oxides (MO: M=Mg, Ca, Sr, Ba) and iron oxides with different crystal types (Fe(x)O(y):Fe(2)O(3) or Fe(3)O(4)) at 300°C. These physical mixtures all showed a synergetic effect toward the degradation of HCB. A range of degradation products were identified by various methods, including tri- to penta-chlorobenzenes by gas chromatography/mass spectrometry (GC-MS), tri- to penta-chlorophenols, tetrachlorocatechol (TCC) and tetrachlorohydroquinone (TCHQ) by GC-MS after derivatization, and formic and acetic acids by ion chromatography. Two degradation pathways, hydrodechlorination and oxidative degradation, appear to occur competitively. However, more sequential chlorinated benzene and phenol congeners were formed over mixed MO/Fe(3)O(4) than over mixed MO/Fe(2)O(3) under the same conditions. The oxidative reaction dominated over mixed MO/Fe(2)O(3) and was promoted as the major reaction by the synergetic effect, while both the oxidative and hydrodechlorination reactions were important over mixed MO/Fe(3)O(4), and both pathways are remarkably promoted by the synergetic effect. The enhanced hydrodechlorination may be attributed to free electrons generated by the transformation of Fe(3)O(4) into Fe(2)O(3), and hydrogen provided by water adsorbed on the MO. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Cation interdiffusion in polycrystalline calcium and strontium titanate

    International Nuclear Information System (INIS)

    Butler, E.P.; Jain, H.; Smyth, D.M.

    1991-01-01

    This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion coefficients are composition independent when the concentration of the calcium cation exceeds that of the strontium cation; otherwise D(C) is strongly composition dependent. Investigations into the effect of cation nonstoichiometry give results that are consistent with a defect incorporation reaction in which excess TiO 2 , within the solid solubility limit, produces A-site cation vacancies as compensating defects. The interdiffusion coefficients increase with increasing concentrations of TiO 2 , so it is concluded that interdiffusion of these alkaline-earth cations in their titanates occurs via a vacancy mechanism

  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)

    Amayri, S.

    2002-11-01

    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) [de

  10. Luminescence properties of Ce3+-activated alkaline earth silicon nitride M2Si5N8 (M = Ca, Sr, Ba) materials

    NARCIS (Netherlands)

    Li, Y.Q.; With, de G.; Hintzen, H.T.J.M.

    2006-01-01

    The luminescence properties of Ce3+, Li+ or Na+ co-doped alkaline-earth silicon nitride M2Si5N8 (M=Ca, Sr, Ba) are reported. The solubility of Ce3+ and optical properties of M2-2xCexLixSi5N8 (x0.1) materials have been investigated as function of the cerium concentration by X-ray powder diffraction

  11. 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

  12. Electrochemical transformations of oxygen and the defect structure of solid solutions on the basis of alkaline earth metal ortho-vanadates

    International Nuclear Information System (INIS)

    Khodos, M.Ya.; Belysheva, G.M.; Brajnina, Kh.Z.

    1986-01-01

    Effect of iso- and heterovalent substitution in the structure of alkaline earth metal ortho-vanadates and synthesis conditions, simulating the definite type of their crystal lattice disordering, on the character of potentiodynamic anodic-cathodic curves has been investigated by the method of cyclic voltammetry. Correlation between signals observed and the defect structure of oxide compounds is refined. Oxygen chemisorption is shown to be determined by concentration of nonequilibrium oxygen vacancies, which formation is accompanied by appearance of quasi-free electrons

  13. Novel 2D or 3D alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand

    Science.gov (United States)

    Du, Zi-Yi; Wen, He-Rui; Xie, Yong-Rong

    2008-11-01

    Three novel alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand, namely, [Ca(O 3SC 2H 4PO 3H)(H 2O) 2] ( 1), [Sr(O 3SC 2H 4PO 3H)] ( 2) and [Ba 2(O 3SC 2H 4PO 3H) 2] ( 3), have been synthesized by hydrothermal reactions. They represent the first structurally characterized alkaline-earth metal complexes of phosphonic acid attached with a sulfonate group. The structure of compound 1 features a 2D layer based on 1D chains of [Ca 2(PO 3) 2] bridged by -CH 2-CH 2-SO 3- groups. Compounds 2 and 3 show pillar-layer architecture based on two different inorganic layers linked by -CH 2-CH 2- groups. The inorganic layer in compound 2 features a 1D chain of edge-sharing SrO 8 polyhedra whereas that in compound 3 features an edge-sharing Ba 2O 14 di-polyhedral unit which is further corner-shared with four neighboring ones. The [O 3S-C 2H 4-PO 3H] 2- ligand shows diverse coordination modes in the three alkaline-earth metal sulfonate-phosphonates.

  14. Alkaline-earth elements of scalp hair and presence of hypertension in housewives: A perspective of chronic effect.

    Science.gov (United States)

    Wang, Bin; Yan, Lailai; Sun, Ying; Yan, Jingjing; Lu, Qun; Zhang, Jingxu; Li, Zhiwen

    2017-08-01

    The relationship between population intakes of alkaline-earth elements (AEEs) and hypertension risk remains under discussion. Hair AEE concentrations can indicate their intake levels into human body. Thus, we aimed to investigate an association of hair AEE concentrations with hypertension risk, and the potential effect of dietary habit on this association. We recruited 398 housewives [163 subjects with hypertension (case group) and 235 subjects without hypertension (control group)] in Shanxi Province of north China. The scalp hair grown in the recent 2 years of each subject was collected and analyzed for the four concerned AEEs [i.e. calcium (Ca), magnesium (Mg), strontium (Sr), and barium (Ba)]. Our study results revealed that median concentrations (μg/g hair) of hair AEEs in the case group were systematically lower than those in control group [i.e. 701 vs. 1271 of Ca, 55.2 vs. 88.3 of Mg, 4.60 vs. 10.4 of Sr, and 1.02 vs. 1.68 of Ba]. Lower levels of the four individual AEEs of hair were associated with an increased presence of hypertension, respectively. Moreover, hair AEE concentrations were all positively correlated with the ingestion frequencies of meat, eggs, fresh vegetables, and fruits, while negatively with that of salted vegetables. A high ingestion frequency of fresh vegetables was associated with a lower prevalence of hypertension with or without adjusting confounders, while salted vegetables revealed a reverse tend. It was concluded that low hair AEEs, as markers of their long-term dietary intake, were associated with the presence of hypertension in a rural Chinese women. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. The complex nature of calcium cation interactions with phospholipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Melcrová, Adéla; Pokorná, Šárka; Pullanchery, S.; Kohagen, Miriam; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cremer, P. S.; Cwiklik, Lukasz

    2016-01-01

    Roč. 6, DEC 2016 (2016), č. článku 38035. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GA16-01074S Institutional support: RVO:61388955 ; RVO:61388963 Keywords : FLUORESCENCE SOLVENT RELAXATION * MOLECULAR-DYNAMICS SIMULATIONS * ALKALINE-EARTH CATION S Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.259, year: 2016

  16. The synthesis and crystal structures of the first rare-earth alkaline-earth selenite chlorides MNd10(SeO3)12Cl8 (M=Ca and Sr)

    International Nuclear Information System (INIS)

    Berdonosov, P.S.; Olenev, A.V.; Dolgikh, V.A.; Lightfoot, P.

    2007-01-01

    Two new alkaline-earth Nd selenite chlorides MNd 10 (SeO 3 ) 12 Cl 8 (M=Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (no. 68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M 11 (SeO 3 ) 12 ] 8+ slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO 3 groups show a pyramidal shape and may be described as SeO 3 E tetrahedra. Such SeO 3 groups decorate the Nd-O skeletons forming the [M 11 (SeO 3 ) 12 ] 8+ slabs. - Graphical abstract: Two new alkaline-earth Nd selenite chlorides MNd 10 (SeO 3 ) 12 Cl 8 (M=Ca, Sr) were synthesized. These structures are constructed by [M 11 (SeO 3 ) 12 ] 8+ slabs separated by chloride anion layers

  17. Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

    2016-07-01

    An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

  18. High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties

    International Nuclear Information System (INIS)

    Gürsoy, M.; Takeda, M.; Albert, B.

    2015-01-01

    Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB 6 , SrB 6 , BaB 6 and the ternary hexaborides Ca x Sr 1−x B 6 , Ca x Ba 1−x B 6 , Sr x Ba 1−x B 6 (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB 6 (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process. - Highlights: • Solid solutions of alkaline earth hexaborides were synthesized. • High-temperature thermoelectric properties of mixed calcium borides are excellent. • Spark plasma source densification results in high ZT values. • Borides are rare-earth free and refractory materials

  19. Removal of toxic and alkali/alkaline earth metals during co-thermal treatment of two types of MSWI fly ashes in China.

    Science.gov (United States)

    Yu, Jie; Qiao, Yu; Jin, Limei; Ma, Chuan; Paterson, Nigel; Sun, Lushi

    2015-12-01

    This study aims to vaporize heavy metals and alkali/alkaline earth metals from two different types of fly ashes by thermal treatment method. Fly ash from a fluidized bed incinerator (HK fly ash) was mixed with one from a grate incinerator (HS fly ash) in various proportions and thermally treated under different temperatures. The melting of HS fly ash was avoided when treated with HK fly ash. Alkali/alkaline earth metals in HS fly ash served as Cl-donors to promote the vaporization of heavy metals during thermal treatment. With temperature increasing from 800 to 900°C, significant amounts of Cl, Na and K were vaporized. Up to 1000°C in air, less than 3% of Cl and Na and less than 5% of K were retained in ash. Under all conditions, Cd can be vaporized effectively. The vaporization of Pb was mildly improved when treated with HS fly ash, while the effect became less pronounced above 900°C. Alkali/alkaline earth metals can promote Cu vaporization by forming copper chlorides. Comparatively, Zn vaporization was low and only slightly improved by HS fly ash. The low vaporization of Zn could be caused by the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4. Under all conditions, less than 20% of Cr was vaporized. In a reductive atmosphere, the vaporization of Cd and Pb were as high as that in oxidative atmosphere. However, the vaporization of Zn was accelerated and that of Cu was hindered because the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4 and copper chloride was depressed in reductive atmosphere. Copyright © 2015. Published by Elsevier Ltd.

  20. Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

    2015-07-01

    Stress corrosion cracking (SCC)can cause failures of CANDU Zircaloy-4 fuel sheathing. The process occurs when a corrosive element (i.e.,iodine) interacts with a susceptible material that is under sufficient strain at a high temperature. Currently, there is an ongoing effort to improve SCC mitigation strategies for future iterations of CANDU reactors. A potential mechanism for SCC mitigation involves utilizing alkali metal oxides and alkaline earth metal oxides that will sequester corrosive iodine while actively repairing a protective oxide layer on the sheath. SCC tests performed with sodium oxide (Na{sub 2}O) and calcium oxide (CaO) have shown to decrease significantly the sheath degradation. (author)

  1. Effect of the kind of alkaline and rare earth ions on the structure of a glass rich in earth; Effet de la nature des ions alcalins et alcalino-terreux sur la structure d un verre riche en terre

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, Arnaud; Caurant, Daniel; Majerus, Odile [Laboratoire de Chimie Appliquee de l Etat Solide, UMR 7574, ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, (France); Lenoir, Marion; Dussossoy, Jean-Luc [Commissariat a l Energie Atomique, Centre d Etudes de la Vallee du Rhone, DIEC/SCDV/LEBM, 30207 Bagnols-sur-Ceze, (France); Charpentier, Thibault [Service de Chimie Moleculaire, DSM/DRECAM/CEA Saclay, 91191 Gif-sur-Yvette Cedex, (France); Neuville, Daniel R. [Laboratoire de Physique des Mineraux et des Magmas, UMR 7047-CNRS-IPGP, Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, (France); Gervais, C. [Laboratoire de Chimie de la matiere condensee, UMR7574, Universite Pierre et Marie Curie, 4 place Jussieu, F-75252 Paris Cedex 05, (France)

    2006-07-01

    In the framework of a structural study of a nuclear wastes containment glass of type alumino borosilicate and rich in rare earths, the influence of the kind of alkaline or rare earth ions is analyzed. For that, two glasses series have been prepared in which the Na{sup +} ion (respectively Ca{sup 2+} ions) present in the standard composition is totally substituted by another alkaline ion Li{sup +}, K{sup +}, Rb{sup +} or Cs{sup +} (respectively another rare earth ion Mg{sup 2+}, Sr{sup 2+} or Ba{sup 2+}). These glasses, analyzed by optical absorption, Raman and {sup 27}Al or {sup 11}B NMR spectroscopies have revealed the strong impact of the kind of the modifying ion as well as the structure of the vitreous lattice (variation of the ratio BO{sub 3}/BO{sub 4} and local variations of the polymerization degree) than the local surroundings of the rare earth (decrease of the covalency degree of the bond Nd-O with the increase of the field force of the modifying ion). (O.M.)

  2. Alkaline cation complexing with calixarenes in electro-spray / mass spectrometry. Specificity for cesium, influence of solvation on ion species and radiolytic stability of the complexing media

    International Nuclear Information System (INIS)

    Allain, Francoise

    2000-01-01

    Radioactive waste management is a rather difficult issue. In order to reduce the volume of waste storage, particularly the Cs 135 (radioactive half-life 2.3 10 6 years), liquid-liquid extraction experiments have shown that crown calixarenes were able to selectively extract cesium cation in wastes. However, the stability under radiolysis of this type of macrocycle is unknown and is the theme of this thesis. Through the coupling of electro-spray and mass spectrometry, the selectivity of crown calixarenes for cesium has been confirmed. The necessity to optimize operating conditions during the utilization of this ionization mode was acknowledged for a correct interpretation of mass spectrum. The solvent nature, source temperature, applied voltage on the cone, gaseous phase stability and species ionization desorption rate are indeed parameters that should be taken into account. Experiments show that the solution species stability is inverse to the one in gaseous phase. In a solution, species stability is linked to the nature of the solvent (solvating power) whereas in gaseous phase, it is linked to the cationic affinity. In the current radiolysis conditions it has been demonstrated that calixarenes have a stable structure. Degradation products are very largely substitution products and do not hinder the caesium cation complexing. Concerning the quantitative aspect, an estimation was produced, however results are not satisfying: reference product synthesis is in fact necessary in order to establish calibration curves that will allow to precisely dose the various components derived from radiolysis [fr

  3. Crystal structures and thermal decomposition of permanganates AE[MnO_4]_2 . n H_2O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    International Nuclear Information System (INIS)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas

    2017-01-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO_4]_2 . 4 H_2O, Sr[MnO_4]_2 . 3 H_2O and Ba[MnO_4]_2 are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO_4]_2 a long time ago, we employed a cation-exchange column loaded with Ba"2"+ cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO_4]_2 . 4 H_2O exhibiting [CaO_8] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO_4]_2 . 3 H_2O with [SrO_1_0] polyhedra adopts the cubic space group P2_13 with a=964.19(7) pm and Z=4. So the harder the AE"2"+ cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO_4]_2 in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO_1_2] polyhedra. During the thermal decomposition of Ca[MnO_4]_2 . 4 H_2O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H_2O molecule at 157 C. The crystal structure of Sr[MnO_4]_2 . 3 H_2O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn_2O_3 and the oxomanganates(III,IV) AEMn_3O_6 (AE=Ca and Sr) remain as final decomposition products at 800 C next to amorphous phases. On the other hand, the already anhydrous Ba[MnO_4]_2 thermally decomposes to hollandite-type BaMn_8O_1_6 and BaMnO_3 at 800 C.

  4. Effect of alkaline earth modifier on the optical and structural properties of Cu2+ doped phosphate glasses as a bandpass filter

    Science.gov (United States)

    Farouk, M.; Samir, A.; El Okr, M.

    2018-02-01

    Glasses of composition [16RO-3Al2O3sbnd 6CuOsbnd 20Na2Osbnd 55P2O5], where R is the alkaline earth (R = Mg, Ca, Sr and Ba mol. %), were prepared by conventional melt quenching technique. The glass samples were characterized by X-ray diffraction, infrared spectroscopy, and spectrophotometer. XRD patterns show no sharp peaks indicating the non-crystalline nature of the prepared glasses. The density and molar volume of the glass systems were determined in order to study their structures. These results revealed that addition of alkaline earth elements leads to the formation of non-bridging oxygens (NBOs) and expands (opens up) the structure. The infrared spectra were analyzed to quantify the present phosphate groups. The optical absorption spectra of Cu2+ ions show the characteristic broadband single of Cu2+ ions in octahedral symmetry. The band gap was estimated following two methodologies. The first method considers the band edge of the transmission, while the second approach relays on the estimated values of the optical constants. A decent agreement for the band gap values using the two methods was obtained.

  5. Structures and heats of formation of simple alkaline earth metal compounds: fluorides, chlorides, oxides, and hydroxides for Be, Mg, and Ca.

    Science.gov (United States)

    Vasiliu, Monica; Feller, David; Gole, James L; Dixon, David A

    2010-09-02

    Geometry parameters, frequencies, heats of formation, and bond dissociation energies are predicted for the simple alkaline earth (Be, Mg and Ca) fluorides, chlorides, oxides, and hydroxides at the coupled cluster theory [CCSD(T)] level including core-valence correlation with the aug-cc-pwCVnZ basis sets up to n = 5 in some cases. Additional corrections (scalar relativistic effects, vibrational zero-point energies, and atomic spin-orbit effects) were necessary to accurately calculate the total atomization energies and heats of formation. The calculated geometry parameters, frequencies, heats of formation, and bond dissociation energies are compared with the available experimental data. For a number of these alkaline earth compounds, the experimental geometries and energies are not reliable. MgF(2) and BeF(2) are predicted to be linear and CaF(2) is predicted to be bent. BeOH is predicted to be bent, whereas MgOH and CaOH are linear. The OBeO angle in Be(OH)(2) is not linear, and the molecule has C(2) symmetry. The heat of formation at 298 K for MgO is calculated to be 32.3 kcal/mol, and the bond dissociation energy at 0 K is predicted to be 61.5 kcal/mol.

  6. Volatilisation of alkali and alkaline earth metallic species during the gasification of a Victorian brown coal in CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Quyn, Dimple Mody; Li, Chun-Zhu [CRC for Clean Power from Lignite, Department of Chemical Engineering, PO Box 36, Monash University, Victoria 3800 (Australia); Hayashi, Jun-ichiro [Centre for Advanced Research of Energy Conversion Materials, Hokkaido University, N13-W8, Kita-ku, Sapporo 060-8628 (Japan)

    2005-08-25

    A Victorian brown coal was gasified in a bench-scale quartz fluidised-bed/fixed-bed reactor in order to study the volatilisation of Na, Ca, and Mg during devolatilisation and gasification and their roles in the reactivity of chars. It was found that the majority of Na was volatilised at 900 {sup o}C under all conditions and that a Na retention limit was achieved in the char with the progress of CO{sub 2} gasification. In some cases, the presence of CO{sub 2} during devolatilisation enhanced the Na retention in the char. In contrast, the retention of Ca (and Mg) was unaffected by CO{sub 2} during devolatilisation at 900C but decreased drastically upon nascent char gasification. The fundamental differences in volatilisation between the alkali and alkaline earth metallic species are discussed in this paper.

  7. 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.

  8. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, X. D.; Fang, Y. M.; Wu, S. Q., E-mail: zzhu@xmu.edu.cn, E-mail: wsq@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Zhu, Z. Z., E-mail: zzhu@xmu.edu.cn, E-mail: wsq@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen 361005 (China)

    2015-05-15

    Single adsorption of different atoms on pristine two-dimensional monolayer MoS{sub 2} 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 MoS{sub 2}. Additionally, local or long-range magnetic moments of two-dimensional MoS{sub 2} sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS{sub 2} monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

  9. Enhanced spin polarization of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend and low-lying shape resonance regions

    International Nuclear Information System (INIS)

    Yuan, J.; Zhang, Z.

    1993-01-01

    Spin polarizations (SP's) of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend (RT) and low-lying shape resonance (SR) regions are calculated using a relativistic method. The detailed SP distributions both with scattering angle and with electron energy are presented via the energy- and angle-dependent surfaces of SP parameters. It is shown that the SP effects of the collisions of electrons with Ca, Sr, and Ba atoms in the RT region are significant in a considerable area on the energy-angle plane and that the spin-orbit interaction is well increased around the low-lying p-wave SR states of Be and Mg and the d-wave SR states of Ca, Sr, and Ba

  10. A first-principles study of half-metallic ferromagnetism in binary alkaline-earth nitrides with rock-salt structure

    International Nuclear Information System (INIS)

    Gao, G.Y.; Yao, K.L.; Liu, Z.L.; Zhang, J.; Min, Y.; Fan, S.W.

    2008-01-01

    In this Letter, using the first-principles full-potential linearized augmented plane-wave (FP-LAPW) method, we extend the electronic structure and magnetism studies on zinc-blende structure of II-V compounds MX (M=Ca,Sr,Ba; X=N,P,As) [M. Sieberer, J. Redinger, S. Khmelevskyi, P. Mohn, Phys. Rev. B 73 (2006) 024404] to the rock-salt structure. It is found that, in the nine compounds, only alkaline-earth nitrides CaN, SrN and BaN exhibit ferromagnetic half-metallic character with a magnetic moment of 1.00μ B per formula unit. Furthermore, compared with the zinc-blende structure of CaN, SrN and BaN, the rock-salt structure has lower energy, which makes them more promising candidates of possible growth of half-metallic films on suitable substrates

  11. Effects of solvent and alkaline earth metals on the heat-induced precipitation process of sodium caseinate.

    Science.gov (United States)

    Lopez, Francesco; Cuomo, Francesca; Nostro, Pierandrea Lo; Ceglie, Andrea

    2013-01-01

    The precipitation temperatures of sodium caseinate in H(2)O and D(2)O in the presence of Mg(2+), Ca(2+), Sr(2+) and Ba(2+) were investigated through fluorescence, turbidity and conductivity experiments. As for the ability of the divalent cations (1-17.5mM) to induce the precipitation process in H(2)O, the sequence Ba(2+) ≥ Ca(2+)>Mg(2+)>Sr(2+) was found. Remarkably, while at low salt concentrations (10mM) the differences among the different cations were greatly reduced. By fitting these results with a modified Jones-Dole equation, we confirmed that the less hydrated ions possess a greater capacity to induce precipitation. In D(2)O, the order of ion ability to induce caseinate precipitation was Ba(2+)>Ca(2+)>Sr(2+)>Mg(2+). The different hydrophobicity between D(2)O and H(2)O was shown to affect significantly the T(Ps) of caseinate in the presence of calcium, strontium and barium. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. 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)

    Vercouter, Thomas; Reiller, Pascal E.; Ansoborlo, Eric; Février, Laureline; Gilbin, Rodolphe; Lomenech, Claire; Philippini, Violaine

    2015-01-01

    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

  13. 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}.

  14. Study of absorption spectra for alkali and alkaline earth metal salts in flameless atomic absorption spectrometry using a carbon tube atomizer

    International Nuclear Information System (INIS)

    Yasuda, Seiji; Kakiyama, Hitoo

    1975-01-01

    Absorption spectra of various salts such as alkali metal salts, alkaline earth dichlorides, and ammonium halides were investigated and absorptions of some molecular species produced in the carbon tube were identified. The aqueous solution (20 μl) containing 1.0 mg/ml of each salt was placed in the carbon tube atomizer and heated in a similar manner to usual flameless atomic absorption method. D 2 -lamp was used as a continuous light source and argon gas was employed as an inert sheath gas. The spectra were obtained over the range of wavelength 200 to 350 nm. When alkali halides were feeded, the absorption spectra agreed with those of alkali halide vapors. Therefore, in such cases vapors of the alkali halides were probably produced by the sublimation or vaporization in the atomizer. The spectra of alkali perchlorates were considered to be those of alkali chlorides produced by the pyrolysis of the perchlorates in the atomizer. The absorptions of alkaline earth chlorides below 250 nm were probably due to their gaseous states. Sulfur dioxide was found to be produced by the pyrolysis of alkali sulfates, bisulfates and sulfites in the atomizer, Alkali phosphates and pyrophosphates gave almost identical spectra below 300 nm. Gamma band spectrum of nitrogen monoxide was observed from 200 to 240 nm during ashing at bout 330 0 C for alkali nitrates and nitrites. Ammonia vapor was produced from ammonium halides during drying at about 170 0 C. Although the absorptions of alkali carbonates and hydroxides were almost undetectable, the same spectra as those of alkali halides were observed by the addition of ammonium halides to the solutions of alkali compounds. This shows that alkali halides are produced in the atomizer by the addition of halide ions. (auth.)

  15. Mineralizer-assisted high-pressure high-temperature synthesis and characterization of novel phosphorus nitride imides and luminescent alkaline earth metal (oxo)nitridophosphates

    International Nuclear Information System (INIS)

    Marchuk, Alexey

    2016-01-01

    The main objectives of this thesis were the synthesis, identification and structural characterization of new alkaline earth metal (oxo)nitridophopshates and phosphorus nitrides. Furthermore, luminescence properties of the resulting materials should be investigated and a connection between these properties and the respective structures should be established. For this purpose, a range of synthesis strategies was employed, including conventional solid-state syntheses in silica ampoules and high-pressure high-temperature syntheses using the multianvil technique. The emphasis of the synthetic part of this thesis lies on the development of new synthetic strategies in order to increase crystallinity of alkaline earth metal (oxo)nitridophosphates and thus accelerate their structure determination. This involves the selection of a suitable mineralizer and the investigation of its interaction with the respective starting materials. In addition, the analytical methods applied in this thesis in order to identify and characterize the compounds are just as essential as the synthesis strategies. X-ray diffraction on single crystals and on powders was carried out as the main analytical method while being supported by quantitative and qualitative 1 H and 31 P solid-state NMR measurements, FTIR and energy-dispersive X-ray (EDX) spectroscopy, as well as electron microscopy methods including both imaging and diffraction techniques. Implied by the large number of novel structures investigated, theoretical studies including topological analysis, calculations of lattice energies and bond-valence sums also played a major role in this thesis. Optical analysis methods such as reflectance spectroscopy, luminescence microscopy and photoluminescence measurements helped to determine the luminescence properties of some of the presented compounds.

  16. Methodological study of the diffusion of interacting cations through clays. Application: experimental tests and simulation of coupled chemistry-diffusion transport of alkaline ions through a synthetical bentonite

    International Nuclear Information System (INIS)

    Melkior, Th.

    2000-01-01

    The subject of this work deals with the project of underground disposal of radioactive wastes in deep geological formations. It concerns the study of the migration of radionuclides through clays. In these materials, the main transport mechanism is assumed to be diffusion under natural conditions. Therefore, some diffusion experiments are conducted. With interacting solutes which present a strong affinity for the material, the duration of these tests will be too long, for the range of concentrations of interest. An alternative is to determine on one hand the geochemical retention properties using batch tests and crushed rock samples and, on the other hand, to deduce the transport parameters from diffusion tests realised with a non-interacting tracer, tritiated water. These data are then used to simulate the migration of the reactive elements with a numerical code which can deal with coupled chemistry-diffusion equations. The validity of this approach is tested by comparing the numerical simulations with the results of diffusion experiments of cations through a clay. The subject is investigated in the case of the diffusion of cesium, lithium and sodium through a compacted sodium bentonite. The diffusion tests are realised with the through-diffusion method. The comparison between the experimental results and the simulations shows that the latter tends to under estimate the propagation of the considered species. The differences could be attributed to surface diffusion and to a decrease of the accessibility to the sites of fixation of the bentonite, from the conditions of clay suspensions in batch tests to the situation of compacted samples. The influence of the experimental apparatus used during the diffusion tests on the results of the measurement has also been tested. It showed that these apparatus have to be taken into consideration when the experimental data are interpreted. A specific model has been therefore developed with the numerical code CASTEM 2000. (author)

  17. Effect of second-sphere cation nature on the character of IR spectra of molybdeum(4, 5) cyanide complexes

    International Nuclear Information System (INIS)

    Zubritskaya, D.I.; Semenishin, D.I.; Vretsena, N.B.; Chernyak, B.I.

    1989-01-01

    The effect of nature of second-sphere cations on IR spectra of molybdeum (4, 5) cyanide complexes is studied. It is found that the increase in the first ionization potential (radius decrease) brings about the increase in the frequency of valent variations ν (CN). This proves the possibility of formation of bridge bonds Mo-CN-M in the compounds (M-alkali, alkaline earth or rare earth metal, Cs, Y). The conclusion is made on a considerable effect of the nature of second-sphere cations and oxidation degree of complexing agent atoms on the nature of IR spectra of octacyanomolybdates (4, 5)

  18. Synthesis of alkaline-earth metal tungstates in melts of [NaNO3-M(NO3)2]eut-Na2WO4 (M=Ca, Sr, Ba) system

    International Nuclear Information System (INIS)

    Shurdumov, G.K.; Shurdumova, Z.V.; Cherkesov, Z.A.; Karmokov, A.M.

    2006-01-01

    Synthesis of alkaline earth metal tungstates in melts of eutectics of NaNO 3 -M(NO 3 ) 2 ] (M=Ca, Sr, Ba) is done. Synthesis is based in exchange reaction of calcium, strontium, and barium nitrates with sodium tungstate [ru

  19. Analyzing Solutions High in Total Dissolved Solids for Rare Earth Elements (REEs) Using Cation Exchange and Online Pre-Concentration with the seaFAST2 Unit; NETL-TRS-7-2017; NETL Technical Report Series; U.S. Department of Energy, National Energy Technology Laboratory: Albany, OR, 2017; p 32

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Torres, M. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Verba, C. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States); Hakala, A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2017-08-01

    The accurate quantification of the rare earth element (REE) dissolved concentrations in natural waters are often inhibited by their low abundances in relation to other dissolved constituents such as alkali, alkaline earth elements, and dissolved solids. The high abundance of these constituents can suppress the overall analytical signal as well as create isobaric interferences on the REEs during analysis. Waters associated with natural gas operations on black shale plays are characterized by high salinities and high total dissolved solids (TDS) contents >150,000 mg/L. Methods used to isolate and quantify dissolved REEs in seawater were adapted in order to develop the capability of analyzing REEs in waters that are high in TDS. First, a synthetic fluid based on geochemical modelling of natural brine formation fluids was created within the Marcellus black shale with a TDS loading of 153,000 mg/L. To this solution, 1,000 ng/mL of REE standards was added based on preliminary analyses of experimental fluids reacted at high pressure and temperature with Marcellus black shale. These synthetic fluids were then run at three different dilution levels of 10, 100, and 1,000–fold dilutions through cation exchange columns using AG50-X8 exchange resin from Eichrom Industries. The eluent from the cation columns were then sent through a seaFAST2 unit directly connected to an inductively coupled plasma mass spectrometer (ICP-MS) to analyze the REEs. Percent recoveries of the REEs ranged from 80–110% and fell within error for the external reference standard used and no signal suppression or isobaric interferences on the REEs were observed. These results demonstrate that a combined use of cation exchange columns and seaFAST2 instrumentation are effective in accurately quantifying the dissolved REEs in fluids that are >150,000 mg/L in TDS and have Ba:Eu ratios in excess of 380,000.

  20. Crystal structures and thermal decomposition of permanganates AE[MnO{sub 4}]{sub 2} . n H{sub 2}O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

    2017-10-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O and Ba[MnO{sub 4}]{sub 2} are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO{sub 4}]{sub 2} a long time ago, we employed a cation-exchange column loaded with Ba{sup 2+} cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O exhibiting [CaO{sub 8}] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O with [SrO{sub 10}] polyhedra adopts the cubic space group P2{sub 1}3 with a=964.19(7) pm and Z=4. So the harder the AE{sup 2+} cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO{sub 4}]{sub 2} in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO{sub 12}] polyhedra. During the thermal decomposition of Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H{sub 2}O molecule at 157 C. The crystal structure of Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn{sub 2}O{sub 3} and the oxomanganates(III,IV) AEMn{sub 3}O{sub 6} (AE=Ca and Sr) remain as final decomposition products at 800 C

  1. Rare earths and rare earth alloys electrolytic preparation process and device for this process

    International Nuclear Information System (INIS)

    Seon, F.; Barthole, G.

    1986-01-01

    Electrolysis of a molten salt of rare earth or rare earth alloy for preparation of the metal or alloy is described. The molten salt bath comprises at least a rare earth chloride, at least an alkaline or alkaline earth chloride and at least an alkaline or alkaline earth fluoride [fr

  2. Effect of compositional variations on charge compensation of AlO4 and BO4 entities and on crystallization tendency of a rare-earth-rich aluminoborosilicate glass

    International Nuclear Information System (INIS)

    Quintas, A.; Caurant, D.; Majerus, O.; Charpentier, T.; Dussossoy, J.-L.

    2009-01-01

    This paper presents the structural and crystallization study of a rare-earth-rich aluminoborosilicate glass that is a simplified version of a new nuclear glass proven to be a potential candidate for the immobilization of highly concentrated radioactive wastes that will be produced in the future. In this work, we studied the impact of changing the nature of alkali (Li + , Na + , K + , Rb + , Cs + ) or alkaline-earth (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ ) cations present in glass composition on glass structure (by 27 Al and 11 B nuclear magnetic resonance spectroscopy) and on its crystallization tendency during melt cooling at 1 K/min (average cooling rate during industrial process). From these composition changes, it was established that alkali cations were preferentially involved in charge compensation of (AlO 4 ) - and (BO 4 ) - entities in the glassy network comparatively to alkaline-earth cations. Whatever the nature of alkali cations, glass compositions containing calcium gave way to the crystallization of an apatite silicate phase bearing calcium and rare-earth (RE) cations (Ca 2 RE 8 (SiO 4 ) 6 O 2 , RE = Nd or La) but melt crystallization tendency during cooling strongly varied with the nature of alkaline-earth cations.

  3. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  4. Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

    2015-07-01

    This work investigates strategies to mitigate stress corrosion cracking (SCC) in Zircaloy-4 sheathing materials. The CANLUB coatings currently used in CANDU reactors contain both alkali metal and alkaline earth metal impurities, which can exist as oxides (e.g., Na{sub 2}O and CaO). It is believed that when the corrosive fission product iodine reacts with these oxides, the iodine can be sequestered through the formation of an iodide (e.g.,NaI and CaI{sub 2}). The subsequent O{sub 2} release may repair cracks in the protective ZrO{sub 2} layer on the sheathing, shielding the Zircaloy-4 sheathing from further corrosive fission product attack. For this investigation, O{sub 2} gas, Na{sub 2}O, and CaO were separately introduced into an environment wherein slotted Zircaloy-4 rings endure mechanical stresses in iodine vapour at high temperatures. Controlled additions of O{sub 2} gas created a slight reduction in the corrosive attack on Zircaloy-4 sheathing, while the inclusion of Na{sub 2}O and CaO lead to greater reductions. (author)

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

    Science.gov (United States)

    Ma, Jin-Gang; Zhang, Cai-Rong; Gong, Ji-Jun; Wu, You-Zhi; Kou, Sheng-Zhong; Yang, Hua; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-08-24

    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.

  6. 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.

  7. Theoretical Study on the Extraction of Alkaline Earth Salts by 18-Crown-6: Roles of Counterions, Solvent Types and Extraction Temperatures

    Directory of Open Access Journals (Sweden)

    Saprizal Hadisaputra

    2014-07-01

    Full Text Available The roles of counterions, solvent types and extraction temperatures on the selectivity of 18-crown-6 (L toward alkaline earth salts MX2 (M = Ca, Sr, Ba; X = Cl-, NO3- have been studied by density functional method at B3LYP level of theory in gas and solvent phase. In gas phase, the chloride anion Cl- is the preference counterion than nitrate anion NO3-. This result is confirmed by the interaction energies, the second order interaction energies, charge transfers, energy difference between HOMO-LUMO and electrostatic potential maps. The presence of solvent reversed the gas phase trend. It is found that NO3- is the preference counterion in solvent phase. The calculated free energies demonstrate that the solvent types strongly change the strength of the complex formation. The free energies are exothermic in polar solvent while for the non polar solvent the free energies are endothermic. As the temperature changes the free energies also vary where the higher the temperatures the lower the free energy values. The calculated free energies are correlated well with the experimental stability constants. This theoretical study would have a strong contribution in planning the experimental conditions in terms of the preference counterions, solvent types and optimum extraction temperatures.

  8. High hydrogen loading of thin palladium wires through alkaline earth carbonates' precipitation on the cathodic surface - evidence of a new phase in the Pd-H system

    International Nuclear Information System (INIS)

    Celani, F.; Spallone, A.; Di Gioacchino, D.; Marini, P.; Di Stefano, V.; Nakamura, M.; Pace, S.; Vecchione, A.; Tripodi, P.

    2000-01-01

    A new protocol for the electrolytic loading of hydrogen (H) in thin palladium (Pd) wires has been developed. In order to increase the cathodic overvoltage, which is known to be the main parameter capable to enhance the electrolytic H loading of Pd, the catalytic action of the Pd surface versus H-H recombination has been strongly reduced by precipitation of a thin layer of alkaline-earth carbonates on the cathode. A set of electrolytes has been employed, containing small amounts of hydrochloric or sulfuric acid and strontium or calcium ions. The H loading has been continuously evaluated through ac measurements of the Pd wire resistance. Uncommonly low resistivity values, leading to an estimate of exceptionally high H loading, have been observed. Evidence of the existence of a new phase in the very high H content region of the Pd-H system has been inferred on the basis of the determination of the temperature coefficient of the electrical resistivity. Mainly for this purpose a thin layer of Hg was galvanically deposed on the cathodic surface, in order to prevent any H deloading during the measurements. The results have been fully reproduced in other 2 well equipped and experienced Laboratories (Italy, USA)

  9. 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.

  10. Structures and Heats of Formation of Simple Alkaline Earth Metal Compounds II: Fluorides, Chlorides, Oxides, and Hydroxides for Ba, Sr, and Ra.

    Science.gov (United States)

    Vasiliu, Monica; Hill, J Grant; Peterson, Kirk A; Dixon, David A

    2018-01-11

    Geometry parameters, vibrational frequencies, heats of formation, bond dissociation energies, cohesive energies, and selected fluoride affinities (difluorides) are predicted for the late alkaline earth (Sr, Ba, and Ra) oxides, fluorides, chlorides, and hydroxides at the coupled cluster theory CCSD(T) level. Additional corrections (scalar relativistic and pseudopotential corrections, vibrational zero-point energies, and atomic spin-orbit effects) were included to accurately calculate the total atomization energies and heats of formation following the Feller-Peterson-Dixon methodology. The calculated values are compared to the experimental data where available. In some cases, especially for Ra compounds, there are no experimental results, or the experimental energetics and geometries are not reliable or have very large error bars. All of the Sr, Ba, and Ra difluorides, dichlorides, and dihydroxides are bent structures with the OMO bond angles decreasing going down the group. The cohesive energies of bulk Be dihalides are predicted to be quite low, while those of Ra are relatively large. The fluoride affinities show that the difluorides are moderately strong Lewis acids and that such trifluorides may form under the appropriate experimental conditions.

  11. Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4′-carboxylphenyl)benzene

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Gong, Yun, E-mail: gongyun7211@cqu.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Lin, Jian Hua, E-mail: jhlin@pku.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2017-01-15

    By using a rigid dicarboxylate ligand, 4,5-di(4′-carboxylphenyl)benzene (H{sub 2}L), two complexes formulated as SrL(DMF)(H{sub 2}O)·(CH{sub 3}CN) (DMF=N,N′-dimethylformamide) (1) and BaL(H{sub 2}O){sub 2} (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV–vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott–Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations. - Graphical abstract: Two alkaline earth metal(II) complexes with 2D layer structures are p-type semiconductors, they possess different band structures and density of states. And the Ba(II) complex 2 exhibits much higher photocurrent density than the Sr(II) complex 1.

  12. Commercial alkaline earth boroaluminosilicate glasses for sealing solid oxide cell stacks Part II: Characterization of devitrification and glass-ceramic phase assemblages

    DEFF Research Database (Denmark)

    Agersted, Karsten; Balic-Zunic, T.

    2018-01-01

    The devitrification process and formation of crystalline phases from commercial alkaline earth boroaluminosilicate glasses containing 48-61 mol% SiO2, 18-28 mol% CaO, 1-7 mol% MgO, 7-10 mol% Al2O3, 1-11 mol% B2O3 plus minor amounts of Na2O, K2O, FeO and TiO2 were quantified through analysis...... of phase assemblages as function of heat treatments above the glass transition temperatures using the electron microprobe and powder X-ray diffraction. Treatments at 800 °C and 850 °C lasted up to 6 weeks. Results indicate that devitrification was strongly activated through presence of heterogeneous...... nucleation, and that the growth mechanism gradually changed from three-dimensional growth at the onset of devitrification towards one-dimensional growth in later stages, when heterogeneous nucleation was absent or less dominating. Most glasses developed entangled and fibrous microstructures with little...

  13. Commercial alkaline earth boroaluminosilicate glasses for sealing solid oxide cell stacks. Part I: Development of glass-ceramic microstructure and thermomechanical properties

    DEFF Research Database (Denmark)

    Agersted, Karsten; Balic-Zunic, Tonci

    2018-01-01

    Sealing performance in solid oxide cell (SOC) stacks and the devitrification process of commercially available alkaline earth boroaluminosilicate glasses containing 48‐61 mol% SiO2, 18‐28 mol% CaO, 1‐7 mol% MgO, 7‐10 mol% Al2O3, 1‐11 mol% B2O3 plus minor amounts of Na2O, K2O, FeO, and TiO2 were...... investigated and quantified through analysis of phase assemblages as function of heat treatments above the glass transition temperatures using the electron microprobe and powder X‐ray diffraction. For two of these glasses devitrification behavior was compared to the devitrification behavior of similar glasses...... produced in the laboratory. Glasses were characterized after annealing in air at 800°C and 850°C for up to 6 weeks. Even though the glasses lie within a relatively narrow compositional range, sealing performance and the resulting microstructures differed significantly. Best thermomechanical properties...

  14. Hydrogen and syngas production by catalytic gasification of algal biomass (Cladophora glomerata L.) using alkali and alkaline-earth metals compounds.

    Science.gov (United States)

    Ebadi, Abdol Ghaffar; Hisoriev, Hikmat; Zarnegar, Mohammad; Ahmadi, Hamed

    2018-01-02

    The steam gasification of algal biomass (Cladophora glomerata L.) in presence of alkali and alkaline-earth metal compounds catalysts was studied to enhance the yield of syngas and reduce its tar content through cracking and reforming of condensable fractions. The commercial catalysts used include NaOH, KHCO 3 , Na 3 PO 4 and MgO. The gasification runs carried out with a research scale, biomass gasification unit, show that the NaOH has a strong potential for production of hydrogen, along with the added advantages of char converting and tar destruction, allowing enhancement of produced syngas caloric value. When the temperature increased from 700°C to 900°C, the tar content in the gas sharply decreased, while the hydrogen yield increased. Increasing steam/biomass ratio significantly increased hydrogen yield and tar destruction; however, the particle size in the range of 0.5-2.5 mm played a minor role in the process.

  15. Transfer of alkaline earth elements in mothers' milk and doses from {sup 45}Ca, {sup 90}Sr and {sup 226}Ra

    Energy Technology Data Exchange (ETDEWEB)

    Smith, T.J.; Phipps, A.W.; Fell, T.P.; Harrison, J.D

    2003-07-01

    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 {sup 45}Ca, {sup 90}Sr and {sup 226}Ra 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 {sup 45}Ca (ratio = 3.1) while, in other cases such as {sup 90}Sr, the infant dose can be a significant fraction of the adult dose. (author)

  16. Recover of some rare earth elements from leach liquor of the Saghand uranium ore using combined precipitation and cation exchange methods

    International Nuclear Information System (INIS)

    Khanchi, A. R.; Rafati, H.; Rezvaniyanzadeh, M. R.

    2008-01-01

    In this research work, the recovery and separation of La(III), Ce(III), Sm(III), Dy(III) and Nd(III) from Saghand uranium ore have been studied by precipitation and ion-exchange chromatography methods using Dowex 50 W-X 8 cation exchanger. At first, some preliminary and preconcentration experiments such as comminution, sieve analysis, gravity table and electrostatic in preconcentration of lanthanides were performed. Then, acidic digesting and leaching procedure were used. The results of experiments showed that rare earth elements, along with interfering ions such as Al(III), Fe(III), Mg(II) and Mn(II) present in the leach liquor solution. The investigation of separation process by precipitation method revealed that precipitation and then fast separation using centrifugal technique had the best results in the elimination of interference elements. In order to separate the lanthanides and to obtain their elution curves, the chromatographic column containing Dowex 50 W-X 8 resin was employed. For efficient separation of lanthanides from interference elements the hydrochloric acid with concentration of two and six molar was used respectively. Recovery of lanthanides from the leach liquor solution was achieved more than 85%

  17. Oxidation of Commercial Petronas Diesel with Tert-Butyl Hydroperoxide Over Poly molybdate Alumina Supported Catalyst Modified With Alkaline Earth Metals

    International Nuclear Information System (INIS)

    Wan Nazwanie Wan Abdullah; Rusmidah Ali; Wan Azlee Wan Abu Bakar

    2016-01-01

    Due to strict environmental legislation for ultra-low sulfur diesel fuels, increasing technical and operational challenges are imposed to conventional hydrodesulfurization (HDS) technology. Therefore, catalytic oxidative desulfurization (Cat-ODS) has been suggested to be an alternative method to replace a conventional method which is hydrodesulfurization. In this study, catalytic oxidation of commercial diesel was performed using an oil-soluble oxidant, tert-butyl hydroperoxide (TBHP), over poly molybdate supported on alumina MoO_3-PO_4/ Al_2O_3 catalyst. A commercial Petronas diesel with 440 ppm of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by (GC-FPD). Alkaline earth metals, such as Calcium (Ca), Barium (Ba) and Strontium (Sr) were introduced on the surface of MoO_3-PO_4/ Al_2O_3. The results showed that the catalytic activity decreased in the order, Ca/ MoO_3-PO_4/ Al_2O_3>Sr/ MoO_3-PO_4/ Al_2O_3> Ba/ MoO_3-PO_4/ Al_2O_3. The Ca/ MoO_3-PO_4/ Al_2O_3 catalyst was characterized by XRD and FESEM. XRD results showed that the best catalyst was highly amorphous while FESEM micrograph illustrated an aggregation and agglomeration of various particle sizes. The catalytic activity of Ca/ MoO_3-PO_4/ Al_2O_3 catalyst with various Ca/ Mo ratios were also studied. When the Ca/ Mo ratio was 15:85, the sulfur removal was the highest (79 %) at 45 degree Celsius, 30 min and O/ S molar ratio 3.0 with solvent = dimethylformamide (DMF), diesel/ solvent ratio = 1.0. (author)

  18. Interaction of Rydberg atoms in circular states with the alkaline-earth Ca(4s{sup 2}) and Sr(5s{sup 2}) atoms

    Energy Technology Data Exchange (ETDEWEB)

    Mironchuk, E. S.; Narits, A. A.; Lebedev, V. S., E-mail: vlebedev@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2015-11-15

    The resonant mechanism of interaction of alkaline-earth atoms having a low electron affinity to Rydberg atoms in circular (l = vertical bar m vertical bar = n–1) and near-circular states has been studied. To describe the dynamics of resonant processes accompanied by nonadiabatic transitions between ionic and Rydberg covalent terms of a quasimolecule, an approach based on the integration of coupled equations for the probability amplitudes has been developed taking into account the possibility of the decay of an anion in the Coulomb field of the positive ionic core of a highly excited atom. The approach involves the specific features of the problem associated with the structure of the wavefunction of a Rydberg electron in states with high orbital angular momenta l ∼ n–1. This approach provides a much more accurate description of the dynamics of electronic transitions at collisions between atoms than that within the modified semiclassical Landau–Zener model. In addition, this approach makes it possible to effectively take into account many channels of the problem. The cross sections for resonant quenching of Rydberg states of the Li(nlm) atom with given principal n, orbital l = n–1, and magnetic m quantum numbers at thermal collisions with the Ca(4s{sup 2}) and Sr(5s{sup 2}) atoms have been calculated. The dependences of the results on n, m, and angle α between the relative velocity of the atoms and the normal to the plane of the orbit of the Rydberg electron have been obtained. The influence of orientational effects on the efficiency of the collisional destruction of circular and near-circular states has been studied. The results indicate a higher stability of such states to their perturbations by neutral particles as compared to usually studied nl states with low values of l (l ≪ n)

  19. Doping of alkali, alkaline-earth, and transition metals in covalent-organic frameworks for enhancing CO2 capture by first-principles calculations and molecular simulations.

    Science.gov (United States)

    Lan, Jianhui; Cao, Dapeng; Wang, Wenchuan; Smit, Berend

    2010-07-27

    We use the multiscale simulation approach, which combines the first-principles calculations and grand canonical Monte Carlo simulations, to comprehensively study the doping of a series of alkali (Li, Na, and K), alkaline-earth (Be, Mg, and Ca), and transition (Sc and Ti) metals in nanoporous covalent organic frameworks (COFs), and the effects of the doped metals on CO2 capture. The results indicate that, among all the metals studied, Li, Sc, and Ti can bind with COFs stably, while Be, Mg, and Ca cannot, because the binding of Be, Mg, and Ca with COFs is very weak. Furthermore, Li, Sc, and Ti can improve the uptakes of CO2 in COFs significantly. However, the binding energy of a CO2 molecule with Sc and Ti exceeds the lower limit of chemisorptions and, thus, suffers from the difficulty of desorption. By the comparative studies above, it is found that Li is the best surface modifier of COFs for CO2 capture among all the metals studied. Therefore, we further investigate the uptakes of CO2 in the Li-doped COFs. Our simulation results show that at 298 K and 1 bar, the excess CO2 uptakes of the Li-doped COF-102 and COF-105 reach 409 and 344 mg/g, which are about eight and four times those in the nondoped ones, respectively. As the pressure increases to 40 bar, the CO2 uptakes of the Li-doped COF-102 and COF-105 reach 1349 and 2266 mg/g at 298 K, respectively, which are among the reported highest scores to date. In summary, doping of metals in porous COFs provides an efficient approach for enhancing CO2 capture.

  20. Molecular Dynamics Study of Crystalline Swelling of Montmorillonite as Affected by Interlayer Cation Hydration

    Science.gov (United States)

    Li, Hongliang; Song, Shaoxian; Dong, Xianshu; Min, Fanfei; Zhao, Yunliang; Peng, Chenliang; Nahmad, Yuri

    2018-04-01

    Swelling of montmorillonite (Mt) is an important factor for many industrial applications. In this study, crystalline swelling of alkali-metal- and alkaline-earth-metal-Mt has been studied through energy optimization and molecular dynamics simulations using the clay force field by Materials Studio 8.0. The delamination and exfoliation of Mt are primarily realized by crystalline swelling caused by the enhanced interlayer cation hydration. The initial position of the interlayer cations and water molecules is the dominated factor for the accuracy of the Mt simulations. Crystalline swelling can be carried out in alkali-metal-Mt and Mg-Mt but with difficulty in Ca-Mt, Sr-Mt and Ba-Mt. The crystalline swelling capacity values are in the order Na-Mt > K-Mt > Cs-Mt > Mg-Mt. This order of crystalline swelling of Mt in the same group can be attributed to the differences between the interlayer cation hydration strengths. In addition, the differences in the crystalline swelling between the alkali-metal-Mt and alkaline-earth-metal-Mt can be primarily attributed to the valence of the interlayer cations.

  1. Two novel alkaline earth coordination polymers constructed from cinnamic acid and 1,10-phenanthroline: synthesis and structural and thermal properties.

    Science.gov (United States)

    Bendjellal, Nassima; Trifa, Chahrazed; Bouacida, Sofiane; Boudaren, Chaouki; Boudraa, Mhamed; Merazig, Hocine

    2018-02-01

    In coordination chemistry and crystal engineering, many factors influence the construction of coordination polymers and the final frameworks depend greatly on the organic ligands used. The diverse coordination modes of N-donor ligands have been employed to assemble metal-organic frameworks. Carboxylic acid ligands can deprotonate completely or partially when bonding to metal ions and can also act as donors or acceptors of hydrogen bonds; they are thus good candidates for the construction of supramolecular architectures. We synthesized under reflux or hydrothermal conditions two new alkaline earth(II) complexes, namely poly[(1,10-phenanthroline-κ 2 N,N')bis(μ-3-phenylprop-2-enoato-κ 3 O,O':O)calcium(II)], [Ca(C 10 H 7 O 2 ) 2 (C 10 H 8 N 2 )] n , (1), and poly[(1,10-phenanthroline-κ 2 N,N')(μ 3 -3-phenylprop-2-enoato-κ 4 O:O,O':O')(μ-3-phenylprop-2-enoato-κ 3 O,O':O)barium(II)], [Ba(C 10 H 7 O 2 ) 2 (C 10 H 8 N 2 )] n , (2), and characterized them by FT-IR and UV-Vis spectroscopies, thermogravimetric analysis (TGA) and single-crystal X-ray diffraction analysis, as well as by powder X-ray diffraction (PXRD) analysis. Complex (1) features a chain topology of type 2,4 C4, where the Ca atoms are connected by O and N atoms, forming a distorted bicapped trigonal prismatic geometry. Complex (2) displays chains of topology type 2,3,5 C4, where the Ba atom is nine-coordinated by seven O atoms of bridging/chelating carboxylate groups from two cinnamate ligands and by two N atoms from one phenanthroline ligand, forming a distorted tricapped prismatic arrangement. Weak C-H...O hydrogen bonds and π-π stacking interactions between phenanthroline ligands are responsible to the formation of a supramolecular three-dimensional network. The thermal decompositions of (1) and (2) in the temperature range 297-1173 K revealed that they both decompose in three steps and transform to the corresponding metal oxide.

  2. Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

    Science.gov (United States)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

    2012-11-01

    This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water

  3. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Squeezing clathrate cages to host trivalent rare-earth guests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States); He, Yuping [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Mordvinova, Natalia E. [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Lebedev, Oleg [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Kovnir, Kirill [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States)

    2017-11-01

    Strike difference of the trivalent rare-earth cations from their alkali and alkaline-earth peers is in the presence of localized 4f-electrons and strong spin-orbit coupling. Placing trivalent rare-earth cations inside the fullerene molecules or in between the blocks of itinerant magnetic intermetallics gave rise to plethora of fascinating properties and materials. A long-time missing but hardly desired piece is the semiconducting or metallic compound where rare-earth cations are situated inside the oversized polyhedral cages of three-dimensional framework. In this work we present a synthesis of such compounds, rare-earth containing clathrates Ba8-xRxCu16P30. The unambiguous proofs of their composition and crystal structure were achieved by a combination of synchrotron powder diffraction, time-of-flight neutron powder diffraction, scanning-transmission electron microscopy, and electron energy-loss spectroscopy. Our quantum-mechanical calculations and experimental characterizations show that the incorporation of the rare-earth cations significantly enhances the hole mobility and concentration which results in the drastic increase in the thermoelectric performance.

  5. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  6. 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.

  7. A comparative study between the dissolution and the leaching methods for the separation of rare earths, uranium and thorium from hydrous metal oxide cake obtained by the alkaline digestion of monazite

    International Nuclear Information System (INIS)

    Chayavadhanangkur, C.; Busamongkol, A.; Hongsirinirachorn, S.; Rodthongkom, C.; Sirisena, K.

    1986-12-01

    Methods for the group-separation of rare-earths, thorium and uranium from hydrous metal oxide cake obtained by the alkaline digestion of monazite were studied. Leaching of the hydrous metal oxide cake at pH between 4-5 separates the elements under investigation into 3 major groups which are suitable to be used as feed materials for further purification. Total dissolution and gradient precipitation at pH 4-5 yields a poorer separation in comparison to the leaching method

  8. Olivine/melt transition metal partitioning, melt composition, and melt structure—Melt polymerization and Qn-speciation in alkaline earth silicate systems

    Science.gov (United States)

    Mysen, Bjorn O.

    2008-10-01

    The two most abundant network-modifying cations in magmatic liquids are Ca 2+ and Mg 2+. To evaluate the influence of melt structure on exchange of Ca 2+ and Mg 2+ with other geochemically important divalent cations ( m-cations) between coexisting minerals and melts, high-temperature (1470-1650 °C), ambient-pressure (0.1 MPa) forsterite/melt partitioning experiments were carried out in the system Mg 2SiO 4-CaMgSi 2O 6-SiO 2 with ⩽1 wt% m-cations (Mn 2+, Co 2+, and Ni 2+) substituting for Ca 2+ and Mg 2+. The bulk melt NBO/Si-range ( NBO/Si: nonbridging oxygen per silicon) of melt in equilibrium with forsterite was between 1.89 and 2.74. In this NBO/Si-range, the NBO/Si(Ca) (fraction of nonbridging oxygens, NBO, that form bonds with Ca 2+, Ca 2+- NBO) is linearly related to NBO/Si, whereas fraction of Mg 2+- NBO bonds is essentially independent of NBO/Si. For individual m-cations, rate of change of KD( m-Mg) with NBO/Si(Ca) for the exchange equilibrium, mmelt + Mg olivine ⇌ molivine + Mg melt, is linear. KD( m-Mg) decreases as an exponential function of increasing ionic potential, Z/ r2 ( Z: formal electrical charge, r: ionic radius—here calculated with oxygen in sixfold coordination around the divalent cations) of the m-cation. The enthalpy change of the exchange equilibrium, Δ H, decreases linearly with increasing Z/ r2 [Δ H = 261(9)-81(3)· Z/ r2 (Å -2)]. From existing information on (Ca,Mg)O-SiO 2 melt structure at ambient pressure, these relationships are understood by considering the exchange of divalent cations that form bonds with nonbridging oxygen in individual Qn-species in the melts. The negative ∂ KD( m-Mg) /∂( Z/ r2) and ∂(Δ H)/∂( Z/ r2) is because increasing Z/ r2 is because the cations forming bonds with nonbridging oxygen in increasingly depolymerized Qn-species where steric hindrance is decreasingly important. In other words, principles of ionic size/site mismatch commonly observed for trace and minor elements in crystals, also

  9. Competitive/co-operative interactions in acid base sandwich: role of cation vs. substituents.

    Science.gov (United States)

    Kalpana, Ayyavoo; Akilandeswari, Lakshminarayanan

    2017-11-15

    The cation-π interaction can be envisaged as a lewis acid base interaction, and it is in line with Pearson's acid base concept. The critical examination of interactions between the π-acids (alkali metal cations - Li + , Na + and alkaline earth metal cations Mg 2+ , Ca 2+ ) on one face and tripodal Cr(CO) 3 moiety on the other π face of substituted arenes demonstrates the role of cation and substitutents in manipulating the interactions between them. The interaction of the two π acids on both faces of arene is not expectedly additive, rather it shows either depreciation of interaction energy revealing the competition of acids toward the base or enhancement of interaction energy denoting a cooperative effect. Among the metal cations under study, Mg 2+ shows a cooperative gesture. Although the substituents play a meek role, they unfailingly exert their electronic effects and are amply documented by excellent correlation of various parameters with the Hammett constant σ m . The elusive switching of λ max from the UV to IR region on binding Mg 2+ with substituted arene-Cr(CO) 3 complex is a characteristic clue that TDDFT can help design the ionic sensors for Mg 2+ cations.

  10. Cation-exchanged SAPO-34 for adsorption-based hydrocarbon separations: predictions from dispersion-corrected DFT calculations.

    Science.gov (United States)

    Fischer, Michael; Bell, Robert G

    2014-10-21

    The influence of the nature of the cation on the interaction of the silicoaluminophosphate SAPO-34 with small hydrocarbons (ethane, ethylene, acetylene, propane, propylene) is investigated using periodic density-functional theory calculations including a semi-empirical dispersion correction (DFT-D). Initial calculations are used to evaluate which of the guest-accessible cation sites in the chabazite-type structure is energetically preferred for a set of ten cations, which comprises four alkali metals (Li(+), Na(+), K(+), Rb(+)), three alkaline earth metals (Mg(2+), Ca(2+), Sr(2+)), and three transition metals (Cu(+), Ag(+), Fe(2+)). All eight cations that are likely to be found at the SII site (centre of a six-ring) are then included in the following investigation, which studies the interaction with the hydrocarbon guest molecules. In addition to the interaction energies, some trends and peculiarities regarding the adsorption geometries are analysed, and electron density difference plots obtained from the calculations are used to gain insights into the dominant interaction types. In addition to dispersion interactions, electrostatic and polarisation effects dominate for the main group cations, whereas significant orbital interactions are observed for unsaturated hydrocarbons interacting with transition metal (TM) cations. The differences between the interaction energies obtained for pairs of hydrocarbons of interest (such as ethylene-ethane and propylene-propane) deliver some qualitative insights: if this energy difference is large, it can be expected that the material will exhibit a high selectivity in the adsorption-based separation of alkene-alkane mixtures, which constitutes a problem of considerable industrial relevance. While the calculations show that TM-exchanged SAPO-34 materials are likely to exhibit a very high preference for alkenes over alkanes, the strong interaction may render an application in industrial processes impractical due to the large amount

  11. Structural and crystallisation study of a rare earth alumino borosilicate glass designed for nuclear waste confinement

    International Nuclear Information System (INIS)

    Quintas, A.

    2007-09-01

    This work is devoted to the study of a rare earth alumino borosilicate glass, which molar composition is 61,81 SiO 2 - 3,05 Al 2 O 3 - 8,94 B 2 O 3 - 14,41 Na 2 O - 6,33 CaO - 1,90 ZrO 2 - 3,56 Nd 2 O 3 , and envisaged for the immobilization of nuclear wastes originating from the reprocessing of high discharge burn up spent fuel. From a structural viewpoint, we investigated the role of the modifier cations on the arrangement of the glass network through different modifications of the glass composition: variation of the Na/Ca ratio and modification of the nature of the alkali and alkaline earth cations. The NMR and Raman spectroscopic techniques were useful to determine the distribution of modifier cations among the glass network and also to cast light on the competition phenomena occurring between alkali and alkaline earth cations for charge compensation of [AlO 4 ] - and [BO 4 ] - species. The neodymium local environment could be probed by optical absorption and EXAFS spectroscopies which enabled to better understand the insertion mode of Nd 3+ ions among the silicate domains of the glass network. Concerning the crystallization behavior we were interested in how the glass composition may influence the crystallization processes and especially the formation of the apatite phase of composition Ca 2 Nd 8 (SiO 4 ) 6 O 2 . In particular, this work underlined the important role of both alkaline earth and rare earth cations on the crystallization of the apatite phase. (author)

  12. Magnetic modulation of exciplex fluorescence of pyrene solutions with azacrown-ether excess in the presence of ions of alkali and alkaline earth metals

    International Nuclear Information System (INIS)

    Borisenko, V.N.; Petrov, N.Kh.; Gromov, S.P.; Alfimov, M.V.

    1997-01-01

    Photoexcitation of polar pyrene solutions with excess of phenylaza-15-crown-5 as a donor results to intermolecular electron transfer with formation of ion-radical pairs, recombination of which produces fluorescent exciplex. Charge exchange between molecules of crown ether and its cation-radicals is practically absent at that. Magnetic effect, observed for fluorescence, decreases, when adding diamagnetic lithium and calcium ions to exiplex pyrene/crown-ether system. This can be explained by formation of paramagnetic complexes. 15 refs., 5 figs

  13. Uranyl and/or rare-earth mellitates in extended organic-inorganic networks: A unique case of hetero-metallic cation-cation interaction with U-VI=O-Ln(III) bonding (Ln = Ce, Nd)

    International Nuclear Information System (INIS)

    Volkringer, Christophe; Henry, Natacha; Grandjean, Stephane; Loiseau, Thierry

    2012-01-01

    A series of uranyl and lanthanide (trivalent Ce, Nd) mellitates (mel) has been hydrothermally synthesized in aqueous solvent. Mixtures of these 4f and 5f elements also revealed the formation of a rare case of lanthanide-uranyl coordination polymers. Their structures, determined by XRD single-crystal analysis, exhibit three distinct architectures. The pure lanthanide mellitate Ln 2 (H 2 O) 6 (mel) possesses a 3D framework built up from the connection of isolated LnO 6 (H 2 O) 3 polyhedra (tri-capped trigonal prism) through the mellitate ligand. The structure of the uranyl mellitate (UO 2 ) 3 (H 2 O) 6 - (mel).11.5H 2 O is lamellar and consists of 8-fold coordinated uranium atoms linked to each other through the organic ligand giving rise to the formation of a 2D 3 6 net. The third structural type, (UO 2 ) 2 Ln(OH)(H 2 O) 3 (mel).2.5H 2 O, involves direct oxygen bondings between the lanthanide and uranyl centers, with the isolation of a hetero-metallic dinuclear motif. The 9-fold coordinated Ln cation, LnO 5 (OH)(H 2 O) 3 , is linked to the 7-fold coordinated uranyl (UO 2 )O-4(OH) (pentagonal bipyramid) via one μ 2 -hydroxo group and one μ 2 -oxo group. The latter is shared between the uranyl bonding (U=O = 1.777(4)1.779(6) angstrom) and a long Ln-O bonding (Ce-O = 2.822(4) angstrom; Nd-O = 2.792(6) angstrom). This unusual linkage is a unique illustration of the so-called cation cation interaction associating 4f and 5f metals. The dinuclear motif is then further connected through the mellitate ligand, and this generates organic inorganic layers that are linked to each other via discrete uranyl (UO 2 )O 4 units (square bipyramid), which ensure the three-dimensional cohesion of the structure. The mixed U-Ln carboxylate is thermally decomposed from 260 to 280 degrees C and then transformed into the basic uranium oxide (U 3 O 8 ) together with U-Ln oxide with the fluorite structural type ('(Ln,U)O 2 '). At 1400 degrees C, only fluorite type '(Ln,U)O 2 ' is formed with

  14. Detection of rare-earth-mineral phases by scanning electron microscopy/energy dispersive x-rays (SEM/EDX) in the alkaline complexes of Tamil Nadu

    International Nuclear Information System (INIS)

    Sengupta, S.K.; Nathan, N.P.; Ganesan, V.; Shome, S.

    2005-01-01

    The alkaline complexes of the Southern Granulite Terrain (SGT) are generally restricted within NNW-SSE-trending Dharmapuri Shear Zone (DSZ), extending from Gudiyatham in the north and Bhavani in the south in Tamil Nadu. REE-rich phases have been studied under EDX (Energy Dispersive X-rays) from the different alkaline suites of Tamil Nadu. In Elagiri, the Th-rich epidote/allanite is concentrically zoned and occurs in the outermost coarse sub-solvus syenite, indicating that the REE concentration is restricted within the late-stage magmatic activity. In Koratti, the apatites are LREE rich. In Samalpatti Complex, the carbonatites host a number of REE-rich minerals commonly classified as betafite, along with nioborutite and nioboilmenite. The niobo-rutile and niobo-ilmenite show exsolved texture. The betafite is zoned with mendelyeerite. Some of the molybdenite in Samalpatti is dendritic indicating incomplete crystallisation. In Sivamalai, the REE phases are generally associated with ferrosyenite and nepheline syenite as adsorbed grains around apatite or carbonate. The REE minerals are Zr-REE titanate, REE-titano silicate and REE-yttrium silicate. In the Pikkili Complex, the REE minerals generally occur as rim around apatite and calcite. A discrete metamict allanite grain with radial cracks occurs within syenite. In Pakkanadu Complex zoned allanite occurs with distinct chemical zonation in syenite. Monazite and celesto-barite are associated with barite suggesting that the REE phases are developed in the late intrusive stage. (author)

  15. Isotherms of ion exchange on titanates of alkaline metals

    International Nuclear Information System (INIS)

    Fillina, L.P.; Belinskaya, F.A.

    1986-01-01

    Present article is devoted to isotherms of ion exchange on titanates of alkaline metals. Therefore, finely dispersed hydrated titanates of alkaline metals (lithium, sodium, potassium) with ion exchange properties are obtained by means of alkaline hydrolysis of titanium chloride at high ph rates. Sorption of cations from salts solution of Li 2 SO 4 , NaNO 3 , Ca(NO 3 ) 2 , AgNO 3 by titanates is studied.

  16. Quantum mechanical study of molecular collisions at ultra-low energy: applications to alkali and alkaline-earth systems; Etude quantique de collisions moleculaires a ultra-basse energie: applications aux alcalins et alcalino-terreux

    Energy Technology Data Exchange (ETDEWEB)

    Quemener, G

    2006-10-15

    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)

  17. Effect of alkaline earth oxides on the physical and spectroscopic properties of Dy3+- doped Li2O-B2O3 glasses for white emitting material application

    Science.gov (United States)

    Shamshad, L.; Rooh, G.; Kirdsiri, K.; Srisittipokakun, N.; Damdee, B.; Kim, H. J.; Kaewkhao, J.

    2017-02-01

    Li2O-MO-B2O3:0.5Dy2O3 glasses mixed with four different alkaline earth modifier oxides MgO, CaO, SrO and BaO were synthesized by melt quench technique. Their physical properties like density, molar volume and refractive index were measured at room temperature and the effect of alkaline earth modifier oxides were studied. Also, optical absorption and photoluminescence spectra of these glasses have been acquired at room temperature. The Judd-Ofelt theory was effectively used to characterize these spectra and spectral intensities (ƒcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties have been determined. Radiative life-times (τR), branching ratios (βcal), and emission cross-sections (σp) and optical gain parameters (σp × τR) were calculated from the Judd-Ofelt intensity parameters and the variation in these parameters with the variation of glass matrix are discussed. Yellow/Blue (Y/B) ratio and chromacity color coordinates (x,y) are calculated from the emission spectra which indicates the white light generation from all the investigated samples. The correlated color temperature (CCT) for the studied glasses is found to be 4418 K. The fluorescence decay time (τexp) of the 4F9/2 level of Dy3+ has been measured from the decay profiles and compared with calculated lifetimes (τcal). Among all the studied glass matrices, the glass containing BaO exhibits high value of branching ratio, large emission cross-section and high optical gain parameter for 6F9/2 → 6H13 at 575 nm. The results indicates the suitability of all the studied glasses for laser action and white light generation.

  18. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  19. A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Michael [Bremen Univ. (Germany). Fachgebiet Kristallographie; University College London (United Kingdom). Dept. of Chemistry; Bell, Robert G. [University College London (United Kingdom). Dept. of Chemistry

    2015-07-01

    Density-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH{sub 4}, CO, N{sub 2}) with the cation sites in the silicoaluminophosphate SAPO-34. Eight different cations from three different groups (alkali cations, alkaline earth cations, transition metals) are included in the study. For each case, the total interaction energy as well as the non-dispersive contribution to the interaction are analysed. Electron density difference plots are used to investigate the nature of this non-dispersive contribution in more detail. Despite a non-negligible contribution of polarisation interactions, the total interaction remains moderate in systems containing main group cations. In SAPOs exchanged with transition metals, orbital interactions between the cations and CO and N{sub 2} lead to a very strong interaction, which makes these systems attractive as adsorbents for the selective adsorption of these species. A critical comparison with experimental heats of adsorption shows reasonable quantitative agreement for CO and N{sub 2}, but a pronounced overestimation of the interaction strength for methane. While this does not affect the conclusions regarding the suitability of TM-exchanged SAPO-34 materials for gas separations, more elaborate computational approaches may be needed to improve the quantitative accuracy for this guest molecule.

  20. A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

    International Nuclear Information System (INIS)

    Fischer, Michael; University College London; Bell, Robert G.

    2015-01-01

    Density-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH 4 , CO, N 2 ) with the cation sites in the silicoaluminophosphate SAPO-34. Eight different cations from three different groups (alkali cations, alkaline earth cations, transition metals) are included in the study. For each case, the total interaction energy as well as the non-dispersive contribution to the interaction are analysed. Electron density difference plots are used to investigate the nature of this non-dispersive contribution in more detail. Despite a non-negligible contribution of polarisation interactions, the total interaction remains moderate in systems containing main group cations. In SAPOs exchanged with transition metals, orbital interactions between the cations and CO and N 2 lead to a very strong interaction, which makes these systems attractive as adsorbents for the selective adsorption of these species. A critical comparison with experimental heats of adsorption shows reasonable quantitative agreement for CO and N 2 , but a pronounced overestimation of the interaction strength for methane. While this does not affect the conclusions regarding the suitability of TM-exchanged SAPO-34 materials for gas separations, more elaborate computational approaches may be needed to improve the quantitative accuracy for this guest molecule.

  1. Capillary electrochromatography of inorganic cations in open tubular columns with a controllable capacity multilayered stationary phase architecture.

    Science.gov (United States)

    Kubán, Pavel; Kubán, Petr; Kubán, Vlastimil; Hauser, Peter C; Bocek, Petr

    2008-05-09

    In this paper capillary electrochromatography of alkali and alkaline-earth metal cations in open tubular capillary columns is described. Capillary columns are prepared by coating fused silica capillaries of 75 microm I.D. with poly(butadiene-maleic acid) copolymer (PBMA) in multiple layers. Thermally initiated radical polymerization is used to crosslink the stationary phase. Capillary columns with different number of stationary phase layers can be prepared and allow for the adjustment of separation selectivity in the electrochromatographic mode. Fast and sensitive separations of common inorganic cations are achieved in less than 6 min in a 60 cm capillary column with on-column capacitively coupled contactless conductivity detector. Limits of detection (S/N=3) for the determination of alkali and alkaline-earth metal cations range from 0.3 to 2.5 microM and repeatability is better than 0.5, 4.5 and 6.1% for migration times, peak heights and peak areas, respectively.

  2. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  3. Tunable electronic and magnetic properties in germanene by alkali, alkaline-earth, group III and 3d transition metal atom adsorption.

    Science.gov (United States)

    Li, Sheng-shi; Zhang, Chang-wen; Ji, Wei-xiao; Li, Feng; Wang, Pei-ji; Hu, Shu-jun; Yan, Shi-shen; Liu, Yu-shen

    2014-08-14

    We performed first-principles calculations to study the adsorption characteristics of alkali, alkali-earth, group III, and 3d transition-metal (TM) adatoms on germanene. We find that the adsorption of alkali or alkali-earth adatoms on germanene has minimal effects on geometry of germanene. The significant charge transfer from alkali adatoms to germanene leads to metallization of germanene, whereas alkali-earth adatom adsorption, whose interaction is a mixture of ionic and covalent, results in semiconducting behavior with an energy gap of 17-29 meV. For group III adatoms, they also bind germanene with mixed covalent and ionic bonding character. Adsorption characteristics of the transition metals (TMs) are rather complicated, though all TM adsorptions on germanene exhibit strong covalent bonding with germanene. The main contributions to the strong bonding are from the hybridization between the TM 3d and Ge pz orbitals. Depending on the induced-TM type, the adsorbed systems can exhibit metallic, half-metallic, or semiconducting behavior. Also, the variation trends of the dipole moment and work function with the adsorption energy across the different adatoms are discussed. These findings may provide a potential avenue to design new germanene-based devices in nanoelectronics.

  4. A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former

    International Nuclear Information System (INIS)

    Sun Yanhui; He Peng; Chen Huani

    2007-01-01

    A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc 2 O 3 to Lu 2 O 3 mediated by the vapor complexes KLnCl 4 and NaLnCl 4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl 3 is in the increasing order ScCl 3 3 3 , and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl 3 > ScCl 3 , and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl 3 and GdCl 3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl 3 , CeCl 3 , YbCl 3 and LuCl 3 , while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl 3 and EuCl 3 . More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl 3 as complex former

  5. Thermal stability and oxidizing properties of mixed alkaline earth-alkali molten carbonates: A focus on the lithium-sodium carbonate eutectic system with magnesium additions

    International Nuclear Information System (INIS)

    Frangini, Stefano; Scaccia, Silvera

    2013-01-01

    Highlights: • TG/DSC analysis was conducted on magnesium-containing eutectic Li/Na eutectic carbonates. • Magnesium influence on the oxygen solubility properties of carbonate was also experimentally determined at 600 °C and 650 °C. • A reproducible partial decarbonation process in premelting region caused formation of magnesium oxycarbonate-like phases. • The acidobase buffering action of magnesium oxycarbonate species could explain the high basic/oxidizing properties of such carbonate melts. • A general correlation between thermal instability in premelting region and basic/oxidizing melt properties was established. - Abstract: A comparative study on thermal behavior and oxygen solubility properties of eutectic 52/48 lithium/sodium carbonate salt containing minor additions of magnesium up to 10 mol% has been made in order to determine whether a general correlation between these two properties can be found or not. Consecutive TG/DSC heating/cooling thermal cycles carried out under alternating CO 2 and N 2 gas flows allowed to assign thermal events observed in the premelting region to a partial decarbonation process of the magnesium-alkali mixed carbonates. The observed decarbonation process at 460 °C is believed to come from initial stage of thermal decomposition of magnesium carbonate resulting in the metastable formation of magnesium oxycarbonate-like phases MgO·2MgCO 3 , in a similar manner as previously reported for lanthanum. Reversible formation and decomposition of the magnesium carbonate phase has been observed under a CO 2 gas atmosphere. The intensity of the decomposition process shows a maximum for a 3 mol% MgO addition that gives also the highest oxygen solubility, suggesting therefore that instability thermal analysis in the premelting region can be considered as providing an effective measure of the basicity/oxidizing properties of alkali carbonate melts with magnesium or, in more general terms, with cations that are strong modifiers of

  6. Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells-Dawson Polyoxometalate.

    Science.gov (United States)

    Hoshino, Takahiro; Isobe, Rina; Kaneko, Takuya; Matsuki, Yusuke; Nomiya, Kenji

    2017-08-21

    A novel compound containing a hexacalcium cluster cation, one carbonate anion, and one calcium cation assembled on a trimeric trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM), [{Ca 6 (CO 3 )(μ 3 -OH)(OH 2 ) 18 }(P 2 W 15 Ti 3 O 61 ) 3 Ca(OH 2 ) 3 ] 19- (Ca 7 Ti 9 Trimer), was obtained as the Na 7 Ca 6 salt (NaCa-Ca 7 Ti 9 Trimer) by the reaction of calcium chloride with the monomeric trititanium(IV)-substituted Wells-Dawson POM species "[P 2 W 15 Ti 3 O 59 (OH) 3 ] 9- " (Ti 3 Monomer). Ti 3 Monomer was generated in situ under basic conditions from the separately prepared tetrameric species with bridging Ti(OH 2 ) 3 groups and an encapsulated Cl - ion, [{P 2 W 15 Ti 3 O 59 (OH) 3 } 4 {μ 3 -Ti(H 2 O) 3 } 4 Cl] 21- (Ti 16 Tetramer). The Na 7 Ca 6 salt of Ca 7 Ti 9 Trimer was characterized by complete elemental analysis, thermogravimetric (TG) and differential thermal analyses (DTA), FTIR, single-crystal X-ray structure analysis, and solution 183 W and 31 P NMR spectroscopy. X-ray crystallography revealed that the [Ca 6 (CO 3 )(μ 3 -OH)(OH 2 ) 18 ] 9+ cluster cation was composed of six calcium cations linked by one μ 6 -carbonato anion and one μ 3 -OH - anion. The cluster cation was assembled, together with one calcium ion, on a trimeric species composed of three tri-Ti(IV)-substituted Wells-Dawson subunits linked by Ti-O-Ti bonds. Ca 7 Ti 9 Trimer is an unprecedented POM species containing an alkaline-earth-metal cluster cation and is the first example of alkaline-earth-metal ions clustered around a titanium(IV)-substituted POM.

  7. Alkylation of isobutane with butenes in the presence of HNaY zeolite modified by cations of nickel, calcium and rare-earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, O.I.; Panchenkov, G.M.; Plakhotnik, V.A.; Razali, B.; Tolkacheva, Y.I.

    1981-01-01

    A study was made of alkylation of isobutane with n-butenes in the presence of ion-exchange forms of zeolites, containing ions of Ni/sup 2 +/ and rare-earth elements. It was established that the addition to HCaY zeolite of Ni/sup 2 +/ ions reduces alkylate yield and increases the content of intermediate products. The use in the reaction studied of HCaY zeolite containing La/sup 3 +/ or Gd/sup 3 +/ ions increases the content of iso-octane hydrocarbons in the alkylate and reduces the content of fractions C/sub 9/ and higher.

  8. Utility of Lithium in Rare-Earth Metal Reduction Reactions to Form Nontraditional Ln2+ Complexes and Unusual [Li(2.2.2-cryptand)]1+ Cations.

    Science.gov (United States)

    Huh, Daniel N; Darago, Lucy E; Ziller, Joseph W; Evans, William J

    2018-02-19

    The utility of lithium compared to other alkali metals in generating Ln 2+ rare-earth metal complexes via reduction of Ln 3+ precursors in reactions abbreviated as LnA 3 /M (Ln = rare-earth metal; A = anionic ligand; M = alkali metal) is described. Lithium reduction of Cp' 3 Ln (Cp' = C 5 H 4 SiMe 3 ; Ln = Y, Tb, Dy, Ho) under Ar in the presence of 2.2.2-cryptand (crypt) forms new examples of crystallographically characterizable Ln 2+ complexes of these metals, [Li(crypt)][Cp' 3 Ln]. In each complex, lithium is found in an N 2 O 4 donor atom coordination geometry that is unusual for the cryptand ligand. Magnetic susceptibility data on these new examples of nontraditional divalent lanthanide complexes are consistent with 4f n 5d 1 electronic configurations. The Dy and Ho complexes have exceptionally high single-ion magnetic moments, 11.35 and 11.67 μ B , respectively. Lithium reduction of Cp' 3 Y under N 2 at -35 °C forms the Y 2+ complex (Cp' 3 Y) 1- , which reduces dinitrogen upon warming to room temperature to generate the (N 2 ) 2- complex [Cp' 2 Y(THF)] 2 (μ-η 2 :η 2 -N 2 ). These results provide insight on the factors that lead to reduced dinitrogen complexes and/or stable divalent lanthanide complexes as a function of the specific reducing agent and conditions.

  9. Alkaline sorbent injection for mercury control

    Science.gov (United States)

    Madden, Deborah A.; Holmes, Michael J.

    2002-01-01

    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.

  10. Comparative study of the ionic exchange of Ca++, Sr++, and Ba++ cations on resins and inorganic exchangers

    International Nuclear Information System (INIS)

    Sanchez Batanero, P.

    1969-03-01

    With a view to applying the results to certain problems related to chemical separations in activation analysis, a study has been made, of the possibilities of separating the alkaline-earth elements Ca, Sr and Ba on organic resins and inorganic exchangers using the radioactive indicator method. The partition coefficients of the cations Ca 2+ , Sr 2+ and Ba 2+ have been measured on Dowex 50 W (NH 4 + ) x 8 resin in the presence of EDTA - NTA - EGTA and DCTA as complexing agents, and on zirconium phosphate, tungstate and molybdate in the presence of HCl and NH 4 Cl. Methods have been developed for separating mixtures of alkaline-earth elements using DCTA-NH 4 + followed by elution on Dowex 50 W (NH 4 + ) x 8 resin columns and on zirconium phosphate. Amongst the complexing agents used on the ion-exchange resins the most promising appears to be DCTA which leads to partition coefficients Ca, Sr and Ba which are very different. The results of measurements of partition coefficients on zirconium phosphate (NH 4 + form) using DCTA-NH 4 + show the interesting possibilities of separations on columns. The separation of the alkaline-earth elements on zirconium phosphate seems to be less quantitative than on Dowex 50 resin; it is however much faster in the former case and this can be useful for treating short half-life radioisotopes in activation analysis. (author) [fr

  11. Rare earths

    International Nuclear Information System (INIS)

    1984-01-01

    The conference was held from September 12 to 13, 1984 in Jetrichovice, Czechoslovakia. The participants heard 16 papers of which 4 were inputted in INIS. These papers dealt with industrial separation processes of rare earths, the use of chemical methods of separation from the concentrate of apatite and bastnesite, the effect of the relative permittivity of solvents in the elution of rare earth elements from a cation exchanger, and the determination of the content of different rare earth elements using X-ray fluorescence analysis and atomic absorption spectroscopy. (E.S.)

  12. Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K-Fr) and alkaline earth (Ca-Ra) elements

    Science.gov (United States)

    Hill, J. Grant; Peterson, Kirk A.

    2017-12-01

    New correlation consistent basis sets based on pseudopotential (PP) Hamiltonians have been developed from double- to quintuple-zeta quality for the late alkali (K-Fr) and alkaline earth (Ca-Ra) metals. These are accompanied by new all-electron basis sets of double- to quadruple-zeta quality that have been contracted for use with both Douglas-Kroll-Hess (DKH) and eXact 2-Component (X2C) scalar relativistic Hamiltonians. Sets for valence correlation (ms), cc-pVnZ-PP and cc-pVnZ-(DK,DK3/X2C), in addition to outer-core correlation [valence + (m-1)sp], cc-p(w)CVnZ-PP and cc-pwCVnZ-(DK,DK3/X2C), are reported. The -PP sets have been developed for use with small-core PPs [I. S. Lim et al., J. Chem. Phys. 122, 104103 (2005) and I. S. Lim et al., J. Chem. Phys. 124, 034107 (2006)], while the all-electron sets utilized second-order DKH Hamiltonians for 4s and 5s elements and third-order DKH for 6s and 7s. The accuracy of the basis sets is assessed through benchmark calculations at the coupled-cluster level of theory for both atomic and molecular properties. Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.

  13. High hydrogen loading of thin palladium wires through alkaline earth carbonates' precipitation on the cathodic surface - evidence of a new phase in the Pd-H system

    Energy Technology Data Exchange (ETDEWEB)

    Celani, F.; Spallone, A.; Di Gioacchino, D. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati, RM (Italy); Marini, P.; Di Stefano, V.; Nakamura, M. [EURESYS, Rome (Italy); Pace, S. [Salerno Univ., Salerno (Italy). Dept. of Physics, Istituto Nazionale per la Fisica della Materia; Mancini, A. [ORIM S.r.l., Piediripa, MC (Italy); Tripodi, P. [Stanford Research Institut International, Stanford, CA (United States)

    2000-07-01

    A new protocol for the electrolytic loading of hydrogen (H) in thin palladium (Pd) wires has been developed. In order to increase the cathodic overvoltage, which is known to be the main parameter capable to enhance the electrolytic H loading of Pd, the catalytic action of the Pd surface versus H-H recombination has been strongly reduced by precipitation of a thin layer of alkaline-earth carbonates on the cathode. A set of electrolytes has been employed, containing small amounts of hydrochloric or sulfuric acid and strontium or calcium ions. The H loading has been continuously evaluated through ac measurements of the Pd wire resistance. Uncommonly low resistivity values, leading to an estimate of exceptionally high H loading, have been observed. Evidence of the existence of a new phase in the very high H content region of the Pd-H system has been inferred on the basis of the determination of the temperature coefficient of the electrical resistivity. Mainly for this purpose a thin layer of Hg was galvanically deposed on the cathodic surface, in order to prevent any H deloading during the measurements. The results have been fully reproduced in other 2 well equipped and experienced Laboratories (Italy, USA).

  14. Effect of high-energy electron irradiation in an electron microscope column on fluorides of alkaline earth elements (CaF2, SrF2, and BaF2)

    International Nuclear Information System (INIS)

    Nikolaichik, V. I.; Sobolev, B. P.; Zaporozhets, M. A.; Avilov, A. S.

    2012-01-01

    The effect of high-energy (150 eV) electron irradiation in an electron microscope column on crystals of fluorides of alkaline earth elements CaF 2 , SrF 2 , and BaF 2 is studied. During structural investigations by electron diffraction and electron microscopy, the electron irradiation causes chemical changes in MF 2 crystals such as the desorption of fluorine and the accumulation of oxygen in the irradiated area with the formation of oxide MO. The fluorine desorption rate increases significantly when the electron-beam density exceeds the threshold value of ∼2 × 10 3 pA/cm 2 ). In BaF 2 samples, the transformation of BaO into Ba(OH) 2 was observed when irradiation stopped. The renewal of irradiation is accompanied by the inverse transformation of Ba(OH) 2 into BaO. In the initial stage of irradiation of all MF 2 compounds, the oxide phase is in the single-crystal state with a lattice highly matched with the MF 2 matrix. When the irradiation dose is increased, the oxide phase passes to the polycrystalline phase. Gaseous products of MF 2 destruction (in the form of bubbles several nanometers in diameter) form a rectangular array with a period of ∼20 nm in the sample.

  15. Alkaline earth metal, silicon, chlorine, hydrogen. A reaction system for the heterogeneous hydrodehalogenation of silicon tetrachloride to nanocrystalline silicon; Erdalkalimetall-Silicium-Chlor-Wasserstoff. Das Reaktionssystem fuer die heterogene Hydrodehalogenierung von Siliciumtetrachlorid bis zum nanokristallinen Silicium

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, Katja

    2012-02-17

    Reactions of an alkaline earth metal with a SiCl{sub 4}-H{sub 2} result in a quaternary system with a metastable quaternary phase which separates into the metal chloride and nanocrystalline silicon upon cooling. The present study was dedicated to a making a detailed characterisation of the quaternary phase. For this purpose the properties of the quaternary system were derived from those of the six binary and four ternary systems. The first ever characterisation of the surface by means of photoelectron spectroscopy was undertaken. It also proved possible for the first time to follow the formation reaction by measuring the potential difference across the reaction system. Using the results of the characterisation the author presents first steps towards identifying the formation mechanism involved. [German] Im quaternaeren System Erdalkalimetall-Silicium-Chlor-Wasserstoff bildet sich bei der Umsetzung des Metalls mit einer SiCl{sub 4}-H{sub 2}-Atmosphaere eine quaternaere Phase. Diese metastabile Phase zerfaellt beim Abkuehlen in das Metallchlorid und Silicium in nanokristalliner Form. Die vorliegende Arbeit hat sich mit der tiefergehenden Charakterisierung der quaternaeren Phase beschaeftigt. Dazu wurden die Eigenschaften des quaternaeren Systems aus den Eigenschaften der sechs binaeren und vier ternaeren Systemen abgeleitet. Die Oberflaeche wurde erstmals mit Photoelektronenspektroskopie charakterisiert. Zusaetzlich gelang erstmalig die Verfolgung der Bildungsreaktion durch Messung des Spannungsabfalls ueber das Reaktionssystem. Erste Ansaetze zur Aufklaerung des Bildungsmechanismus ausgehend von den Ergebnissen der Charakterisierung wurden zusaetzlich aufgezeigt.

  16. Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K-Fr) and alkaline earth (Ca-Ra) elements.

    Science.gov (United States)

    Hill, J Grant; Peterson, Kirk A

    2017-12-28

    New correlation consistent basis sets based on pseudopotential (PP) Hamiltonians have been developed from double- to quintuple-zeta quality for the late alkali (K-Fr) and alkaline earth (Ca-Ra) metals. These are accompanied by new all-electron basis sets of double- to quadruple-zeta quality that have been contracted for use with both Douglas-Kroll-Hess (DKH) and eXact 2-Component (X2C) scalar relativistic Hamiltonians. Sets for valence correlation (ms), cc-pVnZ-PP and cc-pVnZ-(DK,DK3/X2C), in addition to outer-core correlation [valence + (m-1)sp], cc-p(w)CVnZ-PP and cc-pwCVnZ-(DK,DK3/X2C), are reported. The -PP sets have been developed for use with small-core PPs [I. S. Lim et al., J. Chem. Phys. 122, 104103 (2005) and I. S. Lim et al., J. Chem. Phys. 124, 034107 (2006)], while the all-electron sets utilized second-order DKH Hamiltonians for 4s and 5s elements and third-order DKH for 6s and 7s. The accuracy of the basis sets is assessed through benchmark calculations at the coupled-cluster level of theory for both atomic and molecular properties. Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.

  17. Synthesis and chemical modification of polymeric resins for the treatment of cations and aromatic hydrocarbons in produced oily water; Sintese de modificacao quimica de resina polimerica e aplicacao na remocao de cations e hidrocarbonetos aromaticos presentes em agua produzida

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, Thiago M.; Rodrigues, Monique F.; Vieira, Helida V.P.; Queiros, Yure G.C.; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas, Lab. de Macromoleculas e Coloides na Industria do Petroleo, Rio de Janeiro, RJ (Brazil)], e-mail: thiagoaversa@ima.ufrj.br

    2011-07-01

    The use of chemically modified resins in oily water treatment process is not very developed yet. Because of this, this work suggests to study the styrene and divinylbenzene sulfonation effect on oil and grease, aniline and calcium removal from the water. The aniline, oils and greases belong to a class of toxic organic compounds, with the Brazilian maximum limits established for disposal in CONAMA 393/2007, while the calcium ions belong to the group of cations of alkaline earth metals which improve hardness to the water, may cause fouling as carbonates and sulfates form. By using sulfonated resins in oily water treatment it is possible to remove not only oils and greases but also calcium and aniline. These kinds of polar compounds are removed because of the cation exchange capacity of resin. (author)

  18. Preparation and physical properties of rare earth, alkaline earth, and transition metal ternary chalcogenides; Poluchenie i fizicheskie svojtsva trojnykh khal`kogenidov redkozemel`nykh, shchelochnykh i perekhodnykh ehlementov

    Energy Technology Data Exchange (ETDEWEB)

    Georgobiani, A N [RAN, Moskva (Russian Federation). Fizicheskij Inst. im. P.N.Lebedeva; Dzhabbarov, R B; Izzatov, B M; Musaeva, N N; Sultanov, F N; Tagiev, B G; Tagiev, O B [Inst. Fiziki im. G.M.Abdullaeva Akademii nauk Azerbajdzhana, Baku (Azerbaijan)

    1997-02-01

    A study was made on current-voltage characteristics, temperature dependences of electric conductivity and currents of thermoinduced depolarization of monocrystals, including EuGa{sub 2}S{sub 4} and (Ga{sub 2}S{sub 3}){sub 1-x}(Eu{sub 2}O{sub 3}){sub x} solid solutions. It is shown that these compounds, activated by europium, cerium, neodymium and other rare earths, manifest effective luminescence under the effect of ultraviolet and X-radiation, as well as under the effect of electron beams and electric field. 13 refs., 7 figs.

  19. Structural and crystallisation study of a rare earth alumino borosilicate glass designed for nuclear waste confinement; Etude de la structure et du comportement en cristallisation d'un verre nucleaire d'aluminoborosilicate de terre rare

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, A

    2007-09-15

    This work is devoted to the study of a rare earth alumino borosilicate glass, which molar composition is 61,81 SiO{sub 2} - 3,05 Al{sub 2}O{sub 3} - 8,94 B{sub 2}O{sub 3} - 14,41 Na{sub 2}O - 6,33 CaO - 1,90 ZrO{sub 2} - 3,56 Nd{sub 2}O{sub 3}, and envisaged for the immobilization of nuclear wastes originating from the reprocessing of high discharge burn up spent fuel. From a structural viewpoint, we investigated the role of the modifier cations on the arrangement of the glass network through different modifications of the glass composition: variation of the Na/Ca ratio and modification of the nature of the alkali and alkaline earth cations. The NMR and Raman spectroscopic techniques were useful to determine the distribution of modifier cations among the glass network and also to cast light on the competition phenomena occurring between alkali and alkaline earth cations for charge compensation of [AlO{sub 4}]{sup -} and [BO{sub 4}]{sup -} species. The neodymium local environment could be probed by optical absorption and EXAFS spectroscopies which enabled to better understand the insertion mode of Nd{sup 3+} ions among the silicate domains of the glass network. Concerning the crystallization behavior we were interested in how the glass composition may influence the crystallization processes and especially the formation of the apatite phase of composition Ca{sub 2}Nd{sub 8}(SiO{sub 4}){sub 6}O{sub 2}. In particular, this work underlined the important role of both alkaline earth and rare earth cations on the crystallization of the apatite phase. (author)

  20. A case of the tail wagging the dog? Reverse weathering and Earth's CO2 thermostat.

    Science.gov (United States)

    Higgins, J. A.

    2017-12-01

    Feedbacks between climate, the global carbon cycle, and the chemistry of seawater stabilize Earth's surface temperature on geologic timescales and are likely responsible for its habitability over billions of years of Earth history. The most important component of the geologic carbon cycle is the precipitation and burial of carbonate sediments. The amount of carbonate sediment produced depends, in turn, on the alkalinity generated during silicate weathering less the amount consumed during the formation of secondary clay minerals both on the continents and in the ocean. In marine enviroments this process, often referred to as reverse weathering, consumes seawater alkalinity (and cations) via reaction with degraded Al-silicate minerals. Because these reactions constitute a sink of seawater alkalinity, changes in the amount of reverse weathering will lead to imbalances between alkalinity sources and sinks. The net effect is that on timescales greater than the timescale of carbonate compensation (< 10 kyr), changes in reverse weathering will lead to changes in the rate of continental silicate weathering through the dependence of continental silicate weathering on atmospheric CO2 and climate. This mechanism is capable of changing rates of continental silicate weathering without changing either the rate of volcanic outgassing or the rate constant for continental silicate weathering (i.e. through mountain-building or the exposure of different rock types) and as a result represents a unique way of modulating the global carbon cycle and Earth's climate on geologic timescales.

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

    International Nuclear Information System (INIS)

    Zhang Min; Pan Shilie; Han Jian; Yang Zhihua; Su Xin; Zhao Wenwu

    2012-01-01

    A novel ternary lithium strontium borate Li 2 Sr 4 B 12 O 23 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 Li 2 Sr 4 B 12 O 23 crystallizes in the monoclinic space group P2 1 /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 [B 10 O 18 ] 6− network and isolated [B 2 O 5 ] 4− unit. The IR spectrum further confirmed the presence of both BO 3 and BO 4 groups. TG-DSC and Transmission spectrum were reported. Band structures and density of states were calculated. - Graphical abstract: A new phase, Li 2 Sr 4 B 12 O 23 , has been discovered in the ternary M 2 O–M′O–B 2 O 3 (M=alkali-metal, M′=alkalineearth metal) system. The crystal structure consists of [B 10 O 18 ] 6− network and isolated [B 2 O 5 ] 4− unit. Highlights: ► Li 2 Sr 4 B 12 O 23 is a a novel borate discovered in the M 2 O–M′O–B 2 O 3 (M=alkali-metal, M′=alkaline-earth metal) system. ► Li 2 Sr 4 B 12 O 23 crystal structure has a three-dimensional crystal structure with [B 10 O 18 ] 6− network and isolated [B 2 O 5 ] 4− unit. ► Sr 1 and Sr 2 are located in two different channels constructed by 3 ∞ [B 10 O 18 ] network.

  2. Analogy of the Coordination Chemistry of Alkaline Earth Metal and Lanthanide Ln²⁺ Ions: The Isostructural Zoo of Mixed Metal Cages [IM(OtBu)₄{Li(thf)}₄(OH)] (M=Ca, Sr, Ba, Eu), [MM′₆(OPh)₈(thf)₆] (M=Ca, Sr, Ba, Sm, Eu, M′=Li, Na), and their Derivatives with 1,2-Dimethoxyethane

    OpenAIRE

    Maudez, William; Meuwly, Markus; Fromm, Katharina M.

    2008-01-01

    As previously shown, alkali and alkaline earth metal iodides in nonaqueous, aprotic solvents behave like transition metal halides, forming cis- and trans-dihalides with various neutral O-donor ligands. These compounds can be used as precursors for the synthesis of new mixed alkali/alkaline earth metal aggregates. We show here that Ln²⁺ ions form isostructural cluster compounds. Thus, with LiOtBu, 50 % of the initial iodide can be replaced in MI₂, M=Ca, Sr, Ba, Eu, to generate the mixed-metal ...

  3. Methodological study of the diffusion of interacting cations through clays. Application: experimental tests and simulation of coupled chemistry-diffusion transport of alkaline ions through a synthetical bentonite; Etude methodologique de la diffusion de cations interagissants dans les argiles. Application: mise en oeuvre experimentale et modelisation du couplage chimie-diffusion d'alcalins dans une bentonite synthetique

    Energy Technology Data Exchange (ETDEWEB)

    Melkior, Th

    2000-07-01

    The subject of this work deals with the project of underground disposal of radioactive wastes in deep geological formations. It concerns the study of the migration of radionuclides through clays. In these materials, the main transport mechanism is assumed to be diffusion under natural conditions. Therefore, some diffusion experiments are conducted. With interacting solutes which present a strong affinity for the material, the duration of these tests will be too long, for the range of concentrations of interest. An alternative is to determine on one hand the geochemical retention properties using batch tests and crushed rock samples and, on the other hand, to deduce the transport parameters from diffusion tests realised with a non-interacting tracer, tritiated water. These data are then used to simulate the migration of the reactive elements with a numerical code which can deal with coupled chemistry-diffusion equations. The validity of this approach is tested by comparing the numerical simulations with the results of diffusion experiments of cations through a clay. The subject is investigated in the case of the diffusion of cesium, lithium and sodium through a compacted sodium bentonite. The diffusion tests are realised with the through-diffusion method. The comparison between the experimental results and the simulations shows that the latter tends to under estimate the propagation of the considered species. The differences could be attributed to surface diffusion and to a decrease of the accessibility to the sites of fixation of the bentonite, from the conditions of clay suspensions in batch tests to the situation of compacted samples. The influence of the experimental apparatus used during the diffusion tests on the results of the measurement has also been tested. It showed that these apparatus have to be taken into consideration when the experimental data are interpreted. A specific model has been therefore developed with the numerical code CASTEM 2000. (author)

  4. Alkaline earth stannates: The next silicon?

    Energy Technology Data Exchange (ETDEWEB)

    Ismail-Beigi, Sohrab, E-mail: sohrab.ismail-beigi@yale.edu; Ahn, Charles H. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structure and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Walker, Frederick J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structure and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854 (United States); Rabe, Karin M. [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)

    2015-06-01

    Semiconductor materials are being used in an increasingly diverse array of applications, with new device concepts being proposed each year for solar cells, flat-panel displays, sensors, memory, and spin transport. This rapid progress of invention outpaces the development of new semiconductor materials with the required properties and performance. In many applications, high carrier mobility at room temperature is required in addition to specific functional properties critical to the device concept. We review recent developments on high mobility stannate perovskite oxide materials and devices.

  5. Alkaline earth stannates: The next silicon?

    Directory of Open Access Journals (Sweden)

    Sohrab Ismail-Beigi

    2015-06-01

    Full Text Available Semiconductor materials are being used in an increasingly diverse array of applications, with new device concepts being proposed each year for solar cells, flat-panel displays, sensors, memory, and spin transport. This rapid progress of invention outpaces the development of new semiconductor materials with the required properties and performance. In many applications, high carrier mobility at room temperature is required in addition to specific functional properties critical to the device concept. We review recent developments on high mobility stannate perovskite oxide materials and devices.

  6. Specific ion effects on the properties of cationic Gemini surfactant monolayers

    International Nuclear Information System (INIS)

    Alejo, T.; Merchan, M.D.; Velazquez, M.M.

    2011-01-01

    The effects of some anions of the Hofmeister series and different divalent cations of alkaline earth metals on the properties of Langmuir monolayers of the cationic Gemini surfactant ethyl-bis (dimethyl octadecylammonium bromide) have been investigated. Surface pressure and potential isotherms at the air-water interface were obtained on aqueous subphases containing sodium salts with several anions of the Hofmeister series (Cl - , NO 3 - , Br - , I - , ClO 4 - , and SCN - ). The influence of the investigated anions on the monolayer properties can be ordered according to the Hofmeister series with a change in the order between bromide and nitrate anions. On the other hand, for a given anion, the cation of the salt also influences the surface properties of the Langmuir films. The monolayers can be transferred onto mica by the Langmuir-Blodgett technique and then the Langmuir-Blodgett films were characterized by atomic force microscopy (AFM). The AFM images show that the molecules become more closely packed and nearly vertical to the surface when anions screen the electric charge of the surfactant molecules.

  7. Specific ion effects on the properties of cationic Gemini surfactant monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Alejo, T.; Merchan, M.D.; Velazquez, M.M., E-mail: mvsal@usal.es

    2011-06-01

    The effects of some anions of the Hofmeister series and different divalent cations of alkaline earth metals on the properties of Langmuir monolayers of the cationic Gemini surfactant ethyl-bis (dimethyl octadecylammonium bromide) have been investigated. Surface pressure and potential isotherms at the air-water interface were obtained on aqueous subphases containing sodium salts with several anions of the Hofmeister series (Cl{sup -}, NO{sub 3}{sup -}, Br{sup -}, I{sup -}, ClO{sub 4}{sup -}, and SCN{sup -}). The influence of the investigated anions on the monolayer properties can be ordered according to the Hofmeister series with a change in the order between bromide and nitrate anions. On the other hand, for a given anion, the cation of the salt also influences the surface properties of the Langmuir films. The monolayers can be transferred onto mica by the Langmuir-Blodgett technique and then the Langmuir-Blodgett films were characterized by atomic force microscopy (AFM). The AFM images show that the molecules become more closely packed and nearly vertical to the surface when anions screen the electric charge of the surfactant molecules.

  8. Cationic rare-earth metal SALEN complexes.

    Science.gov (United States)

    Liu, Qiancai; Meermann, Christian; Görlitzer, Hans W; Runte, Oliver; Herdtweck, Eberhardt; Sirsch, Peter; Törnroos, Karl W; Anwander, Reiner

    2008-11-28

    Complexes (Salpren(tBu,tBu))Y[N(SiHMe2)2](thf) and (SALEN(tBu,tBu))La[N(SiHMe2)2](thf) (SALEN(tBu,tBu) = Salcyc(tBu,tBu) and Salpren(tBu,tBu)) were prepared from Ln[N(SiHMe2)2]3(thf)2 and H2SALEN(tBu,tBu). The yttrium complex was characterized by X-ray crystallography revealing intrinsic solid-state structural features: the metal centre is displaced by 1.05 angstroms from the [N2O2] least squares plane of a highly bent Salpren(tBu,tBu) ligand (angle(Ph,Ph) dihedral angle of 80.4(1) degrees ) and is coordinated asymmetrically by the silylamide ligand exhibiting one significant Y---(HSi) beta-agostic interaction (Y-N1-Si1, 106.90(9) degrees; Y---Si1, 3.2317(6) angstroms). Complexes (SALEN(tBu,tBu))Ln[N(SiHMe2)2](thf)n (n = 1, Sc; n = 2, Y, La) react with ammonium tetraphenylborate to form the ion pairs [(SALEN(tBu,tBu))Ln(thf)n][BPh4]. The cationisation was proven by X-ray crystal structure analyses of [(Salpren(tBu,tBu))Sc(thf)2][B(C6H5)4].2(thf) and [(Salpren(tBu,tBu))Ln(thf)3][B(C6H5)4].4(thf) (Ln = Y, La), showing an octahedral and pentagonal-bipyramidal coordination geometry, respectively.

  9. Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

    Directory of Open Access Journals (Sweden)

    I. Ssemmanda

    2012-11-01

    Full Text Available This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120–9336 μg g−1 as well as for Sr (9–2150 μg g−1. The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel–dentin junction by a factor of 1.3–1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing

  10. Revisiting isoreticular MOFs of alkaline earth metals: a comprehensive study on phase stability, electronic structure, chemical bonding, and optical properties of A-IRMOF-1 (A = Be, Mg, Ca, Sr, Ba).

    Science.gov (United States)

    Yang, Li-Ming; Vajeeston, Ponniah; Ravindran, Ponniah; Fjellvåg, Helmer; Tilset, Mats

    2011-06-07

    Formation energies, chemical bonding, electronic structure, and optical properties of metal-organic frameworks of alkaline earth metals, A-IRMOF-1 (where A = Be, Mg, Ca, Sr, or Ba), have been systemically investigated with DFT methods. The unit cell volumes and atomic positions were fully optimized with the Perdew-Burke-Ernzerhof functional. By fitting the E-V data into the Murnaghan, Birch and Universal equation of states (UEOS), the bulk modulus and its pressure derivative were estimated and provided almost identical results. The data indicate that the A-IRMOF-1 series are soft materials. The estimated bandgap values are all ca. 3.5 eV, indicating a nonmetallic behavior which is essentially metal independent within this A-IRMOF-1 series. The calculated formation energies for the A-IRMOF-1 series are -61.69 (Be), -62.53 (Mg), -66.56 (Ca), -65.34 (Sr), and -64.12 (Ba) kJ mol(-1) and are substantially more negative than that of Zn-based IRMOF-1 (MOF-5) at -46.02 kJ mol(-1). From the thermodynamic point of view, the A-IRMOF-1 compounds are therefore even more stable than the well-known MOF-5. The linear optical properties of the A-IRMOF-1 series were systematically investigated. The detailed analysis of chemical bonding in the A-IRMOF-1 series reveals the nature of the A-O, O-C, H-C, and C-C bonds, i.e., A-O is a mainly ionic interaction with a metal dependent degree of covalency. The O-C, H-C, and C-C bonding interactions are as anticipated mainly covalent in character. Furthermore it is found that the geometry and electronic structures of the presently considered MOFs are not very sensitive to the k-point mesh involved in the calculations. Importantly, this suggests that sampling with Γ-point only will give reliable structural properties for MOFs. Thus, computational simulations should be readily extended to even more complicated MOF systems.

  11. Alkalinity generation in snowmelt and rain runoff during short distance flow over rock

    Science.gov (United States)

    James L. Clayton

    1998-01-01

    High-elevation ecosystems in the western United States typically have patchy, discontinuous areas of surficial soils surrounded by large areas of rock outcrop, talus, and scree. Snowmelt and precipitation that percolate through soil increase in alkalinity, principally by increasing base cation concentration through cation exchange, and by decreasing acid anion...

  12. Binding properties of oxacalix[4]arenes derivatives toward metal cations

    International Nuclear Information System (INIS)

    Mellah, B.

    2006-11-01

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) 1 H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na + , K + , Ca 2+ , Pb 2+ and Mn 2+ of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li + , Ba 2+ , Zn 2+ and Hg 2+ . A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs + , Ba 2+ , Cu 2+ and Hg 2+ were noted. (author)

  13. Binding properties of oxacalix[4]arenes derivatives toward metal cations; Interactions entre cations metalliques et derives des oxacalix[4]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Mellah, B

    2006-11-15

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) {sup 1}H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na{sup +}, K{sup +}, Ca{sup 2+}, Pb{sup 2+} and Mn{sup 2+} of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li{sup +}, Ba{sup 2+}, Zn{sup 2+} and Hg{sup 2+}. A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs{sup +}, Ba{sup 2+}, Cu{sup 2+} and Hg{sup 2+} were noted. (author)

  14. Variable dimensionality and new uranium oxide topologies in the alkaline-earth metal uranyl selenites AE[UO2)(SeO3)2] (AE=Ca, Ba) and Sr[UO2)(SeO3)2] · 2H2O

    International Nuclear Information System (INIS)

    Almond, Philip M.; Peper, Shane M.; Bakker, Eric; Albrecht-Schmitt, Thomas E.

    2002-01-01

    Three new alkaline-earth metal uranyl selenites, Ca[UO 2 )(SeO 3 ) 2 ] (1), Sr[UO 2 )(SeO 3 ) 2 ] · 2H 2 O (2), and Ba[UO 2 )(SeO 3 ) 2 ] (3), have been prepared from the reactions of CaCO 3 and Ca(OH) 2 , SrCl 2 and Sr(OH) 2 , or BaCl 2 and Ba(OH) 2 with UO 3 and SeO 2 under mild hydrothermal conditions. Single-crystal X-ray diffraction experiments reveal that the structures of 1-3 differ in both connectivity and dimensionality even though all contain the same fundamental building unit, namely [UO 2 (SeO 3 ) 4 ]. This polyhedron consists of a linear uranyl unit that is bound by one chelating and three bridging selenite anions creating a pentagonal bipyramidal environment around the U(VI) center. The crystal structure of 1 contains one-dimensional ribbons where the edges are terminated by monodentate selenite anions. The interior of the ribbons are constructed from edge-sharing pentagonal bipyramidal UO 7 units. The structure of 2 is also one-dimensional; however, here there are chains of edge-sharing pentagonal bipyramidal UO 7 dimers that are connected by bridging selenite anions. Ba[(UO 2 )(SeO 3 ) 2 ] (3) is two-dimensional, and the highly ruffled anionic sheets present in this structure are formed from both bridging and chelating/bridging selenite anions bound to uranyl moieties. The anionic substructures in 1-3 are separated by Ca 2+ , Sr 2+ , or Ba 2+ cations. Crystallographic data (193 K, MoKα, λ=0.71073): 1, triclinic, space group P1-bar, a=5.5502(6) A, b=6.6415(7) A, c=11.013(1) A, α=104.055(2) deg., β=93.342(2) deg., γ=110.589(2) deg. , Z=2, R(F)=4.56% for 100 parameters with 1530 reflections with I>2σ(I); 2, triclinic, space group P1-bar, a=7.0545(5) A, b=7.4656(5) A, c=10.0484(6) A, α=106.995(1) deg., β=108.028(1) deg., γ=98.875(1) deg., Z=2, R(F)= 2.43% for 128 parameters with 2187 reflections with I>2σ(I); 3, monoclinic, space group P2 1 /c, a=7.3067(6) A, b=8.1239(7) A, c=13.651(1) A, β=100.375(2) deg., Z=4, R(F)=4.31% for 105 parameters

  15. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

    2012-01-01

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  16. Uranium in alkaline rocks

    International Nuclear Information System (INIS)

    Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

    1978-04-01

    Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential

  17. Uranium in alkaline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

    1978-04-01

    Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential.

  18. The nature of cationic adsorption sites in alkaline zeolites-single, dual and multiple cation sites

    Czech Academy of Sciences Publication Activity Database

    Nachtigall, P.; Delgado, M. R.; Nachtigallová, Dana; Arean, C. O.

    2012-01-01

    Roč. 14, č. 5 (2012), s. 1552-1569 ISSN 1463-9076 R&D Projects: GA ČR GA203/09/0143 Institutional research plan: CEZ:AV0Z40550506 Keywords : exchanged ZSM-5 zeolites * carbon-monoxide adsorption * low-temperature CO * solid-state NMR * high-silica zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.829, year: 2012

  19. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomeri- zation of the linear propargyl cation to ..... C3, C4 and C5. The ZPE corrections in each case are derived from the. B3LYP calculations. ..... the converse of which gives the relative capacity of the. LPD's to stabilize TS6 with respect ...

  20. Synthesis and photoluminescence of Sm3+ doped alkali alkaline earth borate hosts NaBa4 (BO3)3 and LiSr4(BO3)3

    International Nuclear Information System (INIS)

    Chauhan, A.V.; Nagpure, P.A.; Omanwar, S.K.

    2012-01-01

    In this paper we report the photoluminescence of Sm 3+ doped alkali alkaline borate hosts NaBa 4 (BO 3 ) 3 and LiSr 4 (BO 3 ) 3 . For the synthesis of alkali alkaline borate hosts NaBa 4 (BO 3 ) 3 and LiSr 4 (BO 3 ) 3 doped with different concentrations of Sm 3+ ions, we used the novel combustion technique. The phase purity of the hosts was confirmed by the powder XRD technique. The photoluminescence of the phosphors were carried out within 300 to 700 nm wavelength range. The phosphor shows intense orange red (602 nm) emission for near UV excitation. The FTIR spectra of the phase pure hosts have also been reported. (author)

  1. Modifier cation effects on (29)Si nuclear shielding anisotropies in silicate glasses.

    Science.gov (United States)

    Baltisberger, Jay H; Florian, Pierre; Keeler, Eric G; Phyo, Pyae A; Sanders, Kevin J; Grandinetti, Philip J

    2016-07-01

    We have examined variations in the (29)Si nuclear shielding tensor parameters of SiO4 tetrahedra in a series of seven alkali and alkaline earth silicate glass compositions, Cs2O·4.81 SiO2, Rb2O·3.96 SiO2, Rb2O·2.25 SiO2, K2O·4.48 SiO2, Na2O·4.74 SiO2, BaO·2.64 SiO2, and SrO·2.36 SiO2, using natural abundance (29)Si two-dimensional magic-angle flipping (MAF) experiments. Our analyses of these 2D spectra reveal a linear dependence of the (29)Si nuclear shielding anisotropy of Q((3)) sites on the Si-non-bridging oxygen bond length, which in turn depends on the cation potential and coordination of modifier cations to the non-bridging oxygen. We also demonstrate how a combination of Cu(2+) as a paramagnetic dopant combined with echo train acquisition can reduce the total experiment time of (29)Si 2D NMR measurements by two orders of magnitude, enabling higher throughput 2D NMR studies of glass structure. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Modifier cation effects on 29Si nuclear shielding anisotropies in silicate glasses

    Science.gov (United States)

    Baltisberger, Jay H.; Florian, Pierre; Keeler, Eric G.; Phyo, Pyae A.; Sanders, Kevin J.; Grandinetti, Philip J.

    2016-07-01

    We have examined variations in the 29Si nuclear shielding tensor parameters of SiO4 tetrahedra in a series of seven alkali and alkaline earth silicate glass compositions, Cs2O · 4.81 SiO2, Rb2O · 3.96 SiO2, Rb2O · 2.25 SiO2, K2O · 4.48 SiO2, Na2O · 4.74 SiO2, BaO · 2.64 SiO2, and SrO · 2.36 SiO2, using natural abundance 29Si two-dimensional magic-angle flipping (MAF) experiments. Our analyses of these 2D spectra reveal a linear dependence of the 29Si nuclear shielding anisotropy of Q(3) sites on the Si-non-bridging oxygen bond length, which in turn depends on the cation potential and coordination of modifier cations to the non-bridging oxygen. We also demonstrate how a combination of Cu2+ as a paramagnetic dopant combined with echo train acquisition can reduce the total experiment time of 29Si 2D NMR measurements by two orders of magnitude, enabling higher throughput 2D NMR studies of glass structure.

  3. Advanced alkaline water electrolysis

    International Nuclear Information System (INIS)

    Marini, Stefania; Salvi, Paolo; Nelli, Paolo; Pesenti, Rachele; Villa, Marco; Berrettoni, Mario; Zangari, Giovanni; Kiros, Yohannes

    2012-01-01

    A short review on the fundamental and technological issues relevant to water electrolysis in alkaline and proton exchange membrane (PEM) devices is given. Due to price and limited availability of the platinum group metal (PGM) catalysts they currently employ, PEM electrolyzers have scant possibilities of being employed in large-scale hydrogen production. The importance and recent advancements in the development of catalysts without PGMs are poised to benefit more the field of alkaline electrolysis rather than that of PEM devices. This paper presents our original data which demonstrate that an advanced alkaline electrolyzer with performances rivaling those of PEM electrolyzers can be made without PGM and with catalysts of high stability and durability. Studies on the advantages/limitations of electrolyzers with different architectures do show how a judicious application of pressure differentials in a recirculating electrolyte scheme helps reduce mass transport limitations, increasing efficiency and power density.

  4. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  5. Alkaline fuel cell technology in the lead

    International Nuclear Information System (INIS)

    Nor, J.K.

    2004-01-01

    The Alkaline Fuel Cell (AFC) was the first fuel cell successfully put into practice, a century after William Grove patented his 'hydrogen battery' in 1839. The space program provided the necessary momentum, and alkaline fuel cells became the power source for both the U.S. and Russian manned space flight. Astris Energi's mission has been to bring this technology down to earth as inexpensive, rugged fuel cells for everyday applications. The early cells, LABCELL 50 and LABCELL 200 were aimed at deployment in research labs, colleges and universities. They served well in technology demonstration projects such as the 1998 Mini Jeep, 2001 Golf Car and a series of portable and stationary fuel cell generators. The present third generation POWERSTACK MC250 poised for commercialization is being offered to AFC system integrators as a building block of fuel cell systems in numerous portable, stationary and transportation applications. It is also used in Astris' own E7 and E8 alkaline fuel cell generators. Astris alkaline technology leads the way toward economical, plentiful fuel cells. The paper highlights the progress achieved at Astris, improvements of performance, durability and simplicity of use, as well as the current and future thrust in technology development and commercialization. (author)

  6. 4-(2-Tetrathiafulvalenyl-ethenyl)pyridine (TTF-CH=CH-Py) radical cation salts containing poly(beta-diketonate) rare earth complexes: synthesis, crystal structure, photoluminescent and magnetic properties.

    Science.gov (United States)

    Pointillart, Fabrice; Maury, Olivier; Le Gal, Yann; Golhen, Stéphane; Cador, Olivier; Ouahab, Lahcène

    2009-08-03

    The reactions between the redox-active 4-(2-tetrathiafulvalenyl-ethenyl)pyridine ligand (TTF-CH=CH-Py) and the tris(1,1,1,5,5,5-hexafluoroacetylacetonate)Ln(III) (Ln = La and Nd) lead to the formation of compounds with the formulas {[La(hfac)(5)][(TTF-CH=CH-Py(*+))](2)} (1), {[Nd(hfac)(4)(H(2)O)][(TTF-CH=CH-Py(*+))]}(2) (2), and {[Nd(hfac)(4)(H(2)O)][(TTF-CH=CH-Py(*+))]}(2)(H(2)O)(C(6)H(14))(0.5) (3) (hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate anion). These compounds have been characterized by single-crystal X-ray diffraction, optical, and magnetic measurements. Compounds 1, 2, and 3 crystallize in the monoclinic C2/c, triclinic P1, and monoclinic P2(1)/c space groups, respectively. La(III) adopts a tetradecahedral geometry, while Nd(III) stands in a distorted capped square antiprism one. In 1, the inorganic network is formed by the [La(hfac)(5)](2-) dianionic complexes, while it is formed by a pseudo-dimeric dianionic unit of formula {[Nd(hfac)(4)(H(2)O)](2)}(2-) in 2 and 3. In all crystal structures, the organic network is constituted by the TTF-CH=CH-Py(*+) radical cations. The inorganic and organic networks interact through intermolecular contacts between the pyridine moieties of the TTF-CH=CH-Py(*+) radical cations and the Ln(III) ions. The luminescence properties of the Nd(III) ions (9400 cm(-1)) and fluorescence band of the TTF-CH=CH-Py(*+) radical cations (10200 cm(-1)) have been observed and studied for compound 2. Complexes 2 and 3 are paramagnetic because of Nd(III) ions. Compound 2 is a paramagnetic luminescent TTF-radical-cation-based material. Resistivity measurements have also been performed on these materials.

  7. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  8. Rare earth ion controlled crystallization of mica glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Garai, Mrinmoy; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in

    2016-09-05

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO{sub 2}, Nd{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} doped K{sub 2}O−MgO−B{sub 2}O{sub 3}−Al{sub 2}O{sub 3}−SiO{sub 2}−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm{sup −3}) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T{sub g}) and crystallization temperature (T{sub c}). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg{sub 3}(AlSi{sub 3}O{sub 10})F{sub 2} by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10{sup −6}/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque

  9. Rare earth ion controlled crystallization of mica glass-ceramics

    International Nuclear Information System (INIS)

    Garai, Mrinmoy; Karmakar, Basudeb

    2016-01-01

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO_2, Nd_2O_3, Sm_2O_3 and Gd_2O_3 doped K_2O−MgO−B_2O_3−Al_2O_3−SiO_2−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm"−"3) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T_g) and crystallization temperature (T_c). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg_3(AlSi_3O_1_0)F_2 by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10"−"6/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque fluorophlogopite mica glass-ceramics by single-step heat treatment. • Nanocrystalline glass

  10. Synthesis, characterization, and chemical bonding analysis of the lithium alkaline-earth metal gallide nitrides Li{sub 2}(Ca{sub 3}N){sub 2}[Ga{sub 4}] and Li{sub 2}(Sr{sub 3}N){sub 2}[Ga{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Manisha; Bobnar, Matej; Ormeci, Alim; Hoehn, Peter [Chemische Metallkunde, Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Stoiber, Dominik; Niewa, Rainer [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany); Ovchinnikov, Alexander [Chemische Metallkunde, Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Department of Chemistry and Biochemistry, University of Delaware, Newark, DE (United States)

    2017-11-17

    Large single crystals of Li{sub 2}(Ca{sub 3}N){sub 2}[Ga{sub 4}] and Li{sub 2}(Sr{sub 3}N){sub 2}[Ga{sub 4}] up to several mm in size were grown from mixtures of the respective elements and binary alkaline-earth metal nitrides in reactive lithium melts employing a modified high-temperature centrifugation-aided filtration (HTCAF) technique. The main structural features of these isotypic phases are stella quadrangula building units [Ga{sub 4}]Li{sub 4/2} and octahedra (Nae{sub 6/2}), which form two independent interpenetrating networks. The phases crystallize in the η-carbide structure and represent diamagnetic small bandgap semiconductors. Real-space chemical bonding analysis indicates predominantly ionic bonding. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. 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.

  12. Modelling of marine base cation emissions, concentrations and deposition in the UK

    Directory of Open Access Journals (Sweden)

    M. Werner

    2011-02-01

    Full Text Available Base cations exert a large impact on various geochemical and geophysical processes both in the atmosphere and at the Earth surface. One of the essential roles of these compounds is impact on surface pH causing an increase in alkalinity and neutralizing the effects of acidity generated by sulphur and nitrogen deposition. During recent years anthropogenic emissions of base cations in the UK have decreased substantially, by about 70%, 78%, 75% and 48% for Na+, Mg2+, Ca2+ and K+, respectively, over the period 1990–2006. For the island regions, such as the UK, the main source of base cation particles is the aerosol produced from the sea surface. Here, the sea salt aerosol (SSA emissions are calculated with parameterisations proposed by Mårtensson et al. (2003 for ultra fine particles, Monahan et al. (1986 for fine particles and Smith and Harisson (1998 for coarse particles continuously with a 0.1 μm size step using WRF-modelled wind speed data at a 5 km × 5 km grid square resolution with a 3 h time step for two selected years 2003 and 2006. SSA production has been converted into base cation emissions, with the assumption that the chemical composition of the particle emitted from the sea surface is equal to the chemical composition of sea water, and used as input data in the Fine Resolution Atmospheric Multi-pollutant Exchange Model (FRAME. FRAME model annual mean concentrations and total wet deposition at a 5 km × 5 km grid resolution, are compared with concentrations in air and wet deposition from the National Monitoring Network and measurements based estimates of UK deposition budget. The correlation coefficient for wet deposition achieves high values (R = 0.8 for Na+ and Mg2+, whereas for Ca2+ the correlation is poor (R < 0.3. Base cation concentrations are also represented well, with some overestimations on the west coast and underestimations in the

  13. Constructing and screening a metagenomic library of a cold and alkaline extreme environment

    DEFF Research Database (Denmark)

    Glaring, Mikkel Andreas; Vester, Jan Kjølhede; Stougaard, Peter

    2017-01-01

    Natural cold or alkaline environments are common on Earth. A rare combination of these two extremes is found in the permanently cold (less than 6 °C) and alkaline (pH above 10) ikaite columns in the Ikka Fjord in Southern Greenland. Bioprospecting efforts have established the ikaite columns...

  14. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  15. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir

    2016-03-01

    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  16. Computer simulation of displacement cation exchange chromatography: separation of trivalent actinides and lanthanides

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    1980-05-01

    A first-generation mathematical model of displacement cation exchange chromatography (CES) was constructed. The model incorporated the following phenomena: diffusion of cations up and down the column, diffusion of cations from the bulk liquid to the resin surface, and equilibrium of cations between liquid and solid resin beads. A limited number of experiments with rare earths using DTPA as the separation agent were undertaken to increase the current understanding of the processes involved in cation exchange chromatography. The numerical computer program based on the mathematical model was written in FORTRAN IV for use on the IBM 360 series of computers

  17. A new potentiometric method for the estimation of the rare earth elements

    International Nuclear Information System (INIS)

    Selig, W.S.

    1988-01-01

    Chinese workers recently described a new potentiometric method for lead using sodium tetraphenylborate (NaTPB) as a titrant. Based on a previous Chinese publication, the authors have recently developed a method for the estimation of the alkaline earth metals by sequential titration with NaTPB. In the present work, the authors report a similar method for the estimation of the rare earth elements, including Sc and Y. The sensing electrode is a spectrographic graphite rod, coated with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran as previously described. The reference electrode was a double-junction Ag/AgCl electrode. The titration system is controlled by a Tektronix 4051 graphics computer system. Single cations or mixtures up to 0.5 mequiv are determined by potentiometric titration with 0.05 N NaTPB, after formation of the oxonium cations by reaction with an aqueous solution of poly(ethylene glycol) (PEG). Best results are obtained with PEGs of molecular weights from 8,000 to 20,000. Sequential estimation of Pb + Ba, Sr, and Ca, and the sum of the rare earth elements is also reported, plus possible applications to Al, Ga, and anions precipitated by lead

  18. Alkalinity of the Mediterranean Sea

    OpenAIRE

    Schneider, Anke; Wallace, Douglas W.R.; Körtzinger, Arne

    2007-01-01

    Total alkalinity (AT) was measured during the Meteor 51/2 cruise, crossing the Mediterranean Sea from west to east. AT concentrations were high (∼2600 μmol kg−1) and alkalinity-salinity-correlations had negative intercepts. These results are explained by evaporation coupled with high freshwater AT inputs into coastal areas. Salinity adjustment of AT revealed excess alkalinity throughout the water column compared to mid-basin surface waters. Since Mediterranean waters are supersaturated with r...

  19. Luminescence properties of Eu2+ - activated alkaline-earth silicon-oxynitride MSi2O2-deltaN2+2/3delta (M = Ca, Sr, Ba) : A promising class of novel LED conversion phosphors

    NARCIS (Netherlands)

    Li, Y.Q.; Delsing, A.C.A.; With, de G.; Hintzen, H.T.J.M.

    2005-01-01

    The luminescence properties of Eu2+-activated alk.-earth Si-oxynitrides were studied. In the BaO-SiO2-Si3N4 system, a new BaSi2O2N2 compd. was obtained having the monoclinic structure with lattice parameters a 14.070(4), b 7.276(2), c 13.181(3) .ANG., b 107.74(6)°. All MSi2O2-dN2+2/3d:Eu2+ (M = Ca,

  20. Alkaline fuel cells applications

    Science.gov (United States)

    Kordesch, Karl; Hacker, Viktor; Gsellmann, Josef; Cifrain, Martin; Faleschini, Gottfried; Enzinger, Peter; Fankhauser, Robert; Ortner, Markus; Muhr, Michael; Aronson, Robert R.

    On the world-wide automobile market technical developments are increasingly determined by the dramatic restriction on emissions as well as the regimentation of fuel consumption by legislation. Therefore there is an increasing chance of a completely new technology breakthrough if it offers new opportunities, meeting the requirements of resource preservation and emission restrictions. Fuel cell technology offers the possibility to excel in today's motive power techniques in terms of environmental compatibility, consumer's profit, costs of maintenance and efficiency. The key question is economy. This will be decided by the costs of fuel cell systems if they are to be used as power generators for future electric vehicles. The alkaline hydrogen-air fuel cell system with circulating KOH electrolyte and low-cost catalysed carbon electrodes could be a promising alternative. Based on the experiences of Kordesch [K. Kordesch, Brennstoffbatterien, Springer, Wien, 1984, ISBN 3-387-81819-7; K. Kordesch, City car with H 2-air fuel cell and lead-battery, SAE Paper No. 719015, 6th IECEC, 1971], who operated a city car hybrid vehicle on public roads for 3 years in the early 1970s, improved air electrodes plus new variations of the bipolar stack assembly developed in Graz are investigated. Primary fuel choice will be a major issue until such time as cost-effective, on-board hydrogen storage is developed. Ammonia is an interesting option. The whole system, ammonia dissociator plus alkaline fuel cell (AFC), is characterised by a simple design and high efficiency.

  1. Porous poly(perfluorosulfonic acid) membranes for alkaline water electrolysis

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Andreasen, Jens Wenzel

    2015-01-01

    Poly(perfluorosulfonic acid) (PFSA) is one of a few polymer types that combine excellent alkali resistance with extreme hydrophilicity. It is therefore of interest as a base material in separators for alkaline water electrolyzers. In the pristine form it, however, shows high cation selectivity. T...... for the unmodified membrane. The technological feasibility was demonstrated by testing the membranes in an alkaline water electrolysis cell with encouraging performance.......Poly(perfluorosulfonic acid) (PFSA) is one of a few polymer types that combine excellent alkali resistance with extreme hydrophilicity. It is therefore of interest as a base material in separators for alkaline water electrolyzers. In the pristine form it, however, shows high cation selectivity...... and washed out and the obtained porous materials allowed for swelling to reach water contents up to λ=85 [H2O] [−SO3K]−1. After equilibration in 22 wt% aqueous KOH, ion conductivity of 0.2 S cm−1 was recorded for this membrane type at room temperature, which is significantly higher than 0.01 S cm−1...

  2. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Directory of Open Access Journals (Sweden)

    Eero eSalminen

    2014-02-01

    Full Text Available The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat benzalkonium [ADBA] (alkyldimethylbenzylammonium was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs. Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC. The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  3. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Science.gov (United States)

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-01-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide. PMID:24790972

  4. Method of cleaning alkaline metal

    International Nuclear Information System (INIS)

    Kawakami, Yukio; Naito, Kesahiro; Iizawa, Katsuyuki; Nakasuji, Takashi

    1981-01-01

    Purpose: To prevent scattering of used sodium and aqueous alkaline solution when cleaning used sodium and metallic sodium adhering to equipment with an aqueous alkaline solution. Method: A sodium treating container is filled with an aqueous alkaline solution, and stainless steel gauze is sunk in the container. Equipment to be cleaned such as equipment with sodium adhering to it are retained under the gauze and are thus cleaned. On the other hand, the surface of the aqueous alkaline solution is covered with a fluid paraffin liquid covering material. Thus, the hydrogen produced by the reaction of the sodium and the aqueous alkaline solution will float up, pass through the liquid covering material and be discharged. The sodium will pass through the gauze and float upwardly while reacting with the aqueous alkaline solution in a partic ulate state to the boundary between the aqueous alkaline solution and up to the covering material, and thus the theratment reaction will continue. Thus, the cover material prevents the sodium and the aqueous alkaline solution from scattering. (Kamimura, M.)

  5. Cation-enhanced capillary electrophoresis separation of atropoisomer anions.

    Science.gov (United States)

    Na, Yun-Cheol; Berthod, Alain; Armstrong, Daniel W

    2015-12-01

    CE was used to study the separation of the atropoisomers of four phosphoric acids and two sulfonic acids and the enantiomers of two phosphoric acids. All solutes are in their anionic forms in aqueous electrolytes. The chiral additives were two hydroxypropyl cyclodextrins (CDs) and cyclofructan 6 (CF6). The CDs were able to separate four solutes and the CF6 additive could separate only one: 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BHP). Since CF6 is able to bind with cations, nitrate of alkaline metals, Ba(2+) , and Pb(2+) were added, greatly improving the BHP separation at the expense of longer migration times. There seems to be a link between CF6-cation-binding constants and BHP resolution factors. Cation additions were also performed with CD selectors that are less prone to form complexes with cations. Significant improvements of enantiomer or atropoisomer separations were observed also associated with longer migration times. It is speculated that the anionic solutes associate with the added cations forming larger entities better differentiated by CDs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Experimental data developed to support the selection of a treatment process for West Valley alkaline supernatant

    Energy Technology Data Exchange (ETDEWEB)

    Bray, L.A.; Holton, L.K.; Myers, T.R.; Richardson, G.M.; Wise, B.M.

    1984-01-01

    At the request of West Valley Nuclear Services Co., Inc., the Pacific Northwest Laboratory (PNL) has studied alternative treatment processes for the alkaline PUREX waste presently being stored in Tank 8D2 at West Valley, New York. Five tasks were completed during FY 1983: (1) simulation and characterization of the alkaline supernatant and sludge from the tank. The radiochemical and chemical distributions between the aqueous and solid phase were determined, and the efficiency of washing sludge with water to remove ions such as Na/sup +/ and SO/sub 4//sup 2 -/ was investigated; (2) evaluation of a sodium tetraphenylboron (Na-TPB) precipitation process to recover cesium (Cs) and a sodium titanate (Na-TiA) sorption process to recover strontium (Sr) and plutonium (Pu) from the West Valley Alkaline supernatant. These processes were previously developed and tested at the US Department of Energy's Savannah River Plant; (3) evaluation of an organic cation-exchange resin (Duolite CS-100) to recover Cs and Pu from the alkaline supernatant followed by an organic macroreticular cation exchange resin (Amberlite IRC-718) to recover Sr; (4) evaluation of an inorganic ion exchanger (Linde Ionsiv IE-95) to recover Cs, Sr, and Pu from the alkaline supernatant; and (5) evaluation of Dowex-1,X8 organic anion exchange resin to recover technetium (Tc) from alkaline supernatant. The findings of these tasks are reported. 21 references, 36 figures, 34 tables.

  7. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  8. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Science.gov (United States)

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  9. Effects of cation substitution on thermal expansion and electrical properties of lanthanum chromites

    International Nuclear Information System (INIS)

    Ding Xifeng; Liu Yingjia; Gao Ling; Guo Lucun

    2006-01-01

    The effects of cation substitution on the sintering characteristics, thermal expansion and electrical conductivity properties of La(AE)Cr(M)O 3 (AE=Mg, Ca, Sr, M=Ni, Cu, Co) were investigated. The sinterability of alkaline metal earth (AE)-doped LaCrO 3 increased with AE contents in a sequence of Ca > Sr > Mg. Sr-doped LaCrO 3 sample had a TEC compatible with that of 8YSZ electrolyte. The transition metals of Ni, Co and Cu substituted in Cr-site further optimized the sinterability of La 0.85 Sr 0.15 CrO 3 in air. Ni and Co could effectively enhance the electrical conductivity from room temperature to 1123 K though the concomitant increase in TEC was distinctively large with Co doping. The TEC was controlled by co-doping Ni and Co in Cr-site, and La 0.85 Sr 0.15 Cr 0.95 Ni 0.02 Co 0.02 O 3 exhibited a TEC of 10.9 x 10 -6 /K, which was matched with that of 8YSZ, indicating that it could be suitable to be used as an SOFC interconnect material

  10. Mechanistic studies of the alkaline degradation of cellulose in cement

    International Nuclear Information System (INIS)

    Greenfield, B.F.; Robertson, G.P.; Spindler, M.W.; Harrison, W.N.; Somers, P.J.

    1993-07-01

    The alkaline degradation of cellulose-based materials under conditions simulating those of a deep underground radioactive waste repository has been investigated. A number of key degradation products, of which 2-C-(hydroxymethyl)-3-deoxy-D-pentonic acid (isosaccharinic acid) is the most important, have been synthesised, and the solubilities of their plutonium complexes have been determined. Analysis of leachates of anaerobically degraded cellulose has shown concentrations of organic acids which are broadly consistent with the enhanced plutonium solubilities found in these leachates. Reaction mechanisms have been identified that can lead to isosaccharinic acid production by non-oxidative transformations, which may be catalysed by some divalent cations. (Author)

  11. 生物活性稀土梯度涂层在碱液环境中的电极化后处理%Electric polarized post treatment of rare earth active bioceramic gradient coating in alkaline solution

    Institute of Scientific and Technical Information of China (English)

    汪震; 刘其斌; 肖明; 杨邦成

    2011-01-01

    To improve the quality of rare earth active bioceramic gradient coatings,a method of electric polarized treatment(PAS) was used to post-process the gradient coatings fabricated by wide band laser cladding in alkali liquid.The phases and corrosion resistance of the bioceramic coatings were analyzed by XRD and an electrochemical analyzer.The bioceramic coatings were immersed in simulated body fluid(SBF) to examine its bioactivity and its electrical charge.The experimental results indicate that PAS treatment not only improves the crystallinity of the coatings,but also is favourable to transform additional phases into hydroxyapatite.PAS treatment exhibits a little effect on corrosion resistance of the bioceramic coatings.Compared with as-received coatings,the coatings treated by PAS are of better bioactivity and more negative charge.%为了改善活性生物稀土梯度涂层的质量,在碱液环境中采用电极化处理法(PAS)对宽带激光熔覆生物活性稀土梯度涂层进行后处理。利用XRD和电化学分析仪对涂层的相组成和耐腐蚀性进行了研究,通过模拟体液浸泡试验考察了生物陶瓷涂层的生物活性和涂层表面的电荷分布情况。结果表明,碱液环境中电极化处理法(PAS)能够提高涂层的结晶度,使涂层中的非晶相、杂相向羟基磷灰石转化。PAS对涂层的耐腐蚀性影响不大。与未处理涂层相比,PAS处理后的涂层生物活性更好,且涂层表面产生了更多的负电荷。

  12. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  13. Corrosion inhibition by inorganic cationic inhibitors on the high strength alumunium alloy, 2024-T3

    Science.gov (United States)

    Chilukuri, Anusha

    The toxicity and carcinogenic nature of chromates has led to the investigation of environmentally friendly compounds that offer good corrosion resistance to AA 2024-T3. Among the candidate inhibitors are rare earth metal cationic (REM) and zinc compounds, which have received much of attention over the past two decades. A comparative study on the corrosion inhibition caused by rare earth metal cations, Ce3+, Pr3+, La3+ and Zn2+ cations on the alloy was done. Cathodic polarization showed that these inhibitor ions suppress the oxygen reduction reaction (ORR) to varying extents with Zn2+ providing the best inhibition. Pr3+ exhibited windows of concentration (100-300 ppm) in which the corrosion rate is minimum; similar to the Ce3+ cation. Scanning Electron Microscopy (SEM) studies showed that the mechanism of inhibition of the Pr3+ ion is also similar to that of the Ce3+ ion. Potentiodynamic polarization experiments after 30 min immersion time showed greatest suppression of oxygen reduction reaction in neutral chloride solutions (pH 7), which reached a maximum at a Zn2+ ion concentration of 5 mM. Anodic polarization experiments after 30 min immersion time, showed no anodic inhibition by the inhibitor in any concentration (0.1 mM - 10 mM) and at any pH. However, anodic polarization of samples immersed after longer immersion times (upto 4 days) in mildly acidic Zn2+ (pH 4) solutions showed significant reduction in anodic kinetics indicating that zinc also acts as a “slow anodic inhibitor”. In contrast to the polarization experiments, coupons exposed to inhibited acidic solutions at pH 4 showed complete suppression of dissolution of Al2CuMg particles compared to zinc-free solutions in the SEM studies. Samples exposed in pH 4 Zn2+-bearing solution exhibited highest polarization resistance which was also observed to increase with time. In deaerated solutions, the inhibition by Zn2+ at pH 4 is not observed as strongly. The ability to make the interfacial electrolyte

  14. Ammonothermal synthesis of alkali-alkaline earth metal and alkali-rare earth metal carbodiimides. K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}

    Energy Technology Data Exchange (ETDEWEB)

    Mallmann, Mathias; Haeusler, Jonas; Cordes, Niklas; Schnick, Wolfgang [Department of Chemistry, University of Munich (LMU) (Germany)

    2017-12-13

    Alkali-alkaline earth metal and alkali-rare earth metal carbodiimides, namely K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (x = 0 - 1) (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}, were synthesized under ammonothermal conditions in high-pressure autoclaves. The structures of the three compounds can be derived from homeotypic K{sub 5}H(CN{sub 2}){sub 3} and Na{sub 5}H(CN{sub 2}){sub 3} by partial substitution of K{sup +} or Na{sup +}by Sr{sup 2+} or Eu{sup 2+}. The reactions were carried out in two step syntheses (T{sub 1} = 673 K, T{sub 2} = 823 K) starting from sodium or potassium azide, dicyandiamide and strontium or Eu(NH{sub 2}){sub 2}, respectively. The crystal structures were solved and refined from single-crystal X-ray diffraction data [K{sub 4.16}Sr{sub 0.84}(CN{sub 2}){sub 2.84}(HCN{sub 2}){sub 0.16}: space group Im3m (no. 229), a = 7.8304(5) Aa, Z = 2, R{sub 1} = 0.024, wR{sub 2} = 0.052; K{sub 4.40}Eu{sub 0.60}(CN{sub 2}){sub 2.60}(HCN{sub 2}){sub 0.40}: space group Im anti 3m (no. 229), a = 7.8502(6) Aa, Z = 2, R{sub 1} = 0.022, wR{sub 2} = 0.049]. In contrast to the potassium carbodiimides, the sodium-strontium carbodiimide was only synthesized as microcrystalline powder. The crystal structure was determined by powder X-ray diffraction and refined by the Rietveld method [Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}: space group Im3m (no. 229), a = 7.2412(1) Aa, Z = 2, R{sub wp} = 0.050]. The presence of hydrogencyanamide units ([HNCN]{sup -}) next to carbodiimide units ([CN{sub 2}]{sup 2-}) in all compounds was confirmed by FT-IR spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Antimony(3) ethylenediaminetetraacetate complexes with single- and doubly charged cations

    International Nuclear Information System (INIS)

    Davidovich, R.L.; Logvinova, V.B.; Kajdalova, T.A.

    1998-01-01

    The antimony(3) ethylenediaminetetraacetate complexes with alkaline and bivalent metals cations of the M + Sb(Edta) · H 2 O (M + = K, Rb, Cs, NH 4 ), M 2+ [Sb(Edta)] 2 · 8H 2 O (M 2+ = Mg, Ca, Sr, Co, Cd) composition are synthesized. Roentgenographic and IR-spectroscopic characteristics of the synthesized substances are determined. Two groups of the isostructural compounds: M + Sb(Edta) · H 2 O (M + = K, Rb, NH 4 ) and M 2+ [Sb(Edta)] 2 · 8H 2 O (M 2+ = Mg, Ca, Sr, Mn, Co, Cd) are established [ru

  16. Design of Perovskite Oxides as Anion-Intercalation-Type Electrodes for Supercapacitors: Cation Leaching Effect.

    Science.gov (United States)

    Liu, Yu; Dinh, Jim; Tade, Moses O; Shao, Zongping

    2016-09-14

    Oxygen ions can be exploited as a charge carrier to effectively realize a new type of anion-intercalation supercapacitor. In this study, to get some useful guidelines for future materials development, we comparatively studied SrCoO3-δ (SC), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), and Co3O4 as electrodes in supercapacitors with aqueous alkaline electrolyte. The effect of interaction between the electrode materials with the alkaline solution was focused on the structure and specific surface area of the electrode material, and ultimately the electrochemical performance was emphasized. Both BSCF and SC were found to experience cation leaching in alkaline solution, resulting in an increase in the specific surface area of the material, but overleaching caused the damage of perovskite structure of BSCF. Barium leaching was more serious than strontium, and the cation leaching was component dependent. Although high initial capacitance was achieved for BSCF, it was not a good candidate as intercalation-type electrode for supercapacitor because of poor cycling stability from serious Ba(2+) and Sr(2+) leaching. Instead, SC was a favorable electrode candidate for practical use in supercapacitors due to its high capacity and proper cation leaching capacity, which brought beneficial effect on cycling stability. It is suggested that cation leaching effect should be seriously considered in the development of new perovskite materials as electrodes for supercapacitors.

  17. Uranium prospecting in alkaline mountain chimneys of Serra Negra and Salitre - Minas Gerais, Brasil

    International Nuclear Information System (INIS)

    Souza Filho, J.G.C.

    1974-01-01

    The occurence of radioactive minerals such as apatite and pyrochlore, in the alkaline chimneys of Serra Negra and Salitre (Minas Gerais, Brazil), is discussed. Also mentioned are other minerals of interest associated with the alkaline magma such as columbite, fluorite, monazite, zircon, baddeleyite, etc, which in favourable conditions may occur in deposits of great economical value, and which may present high contents of rare earths, thorium and uranium

  18. Effect of certain alkaline metals on Pr doped glasses to investigate spectroscopic studies

    Science.gov (United States)

    Lenkennavar Susheela, K.; Madhu, A.; Eraiah, B.; Kokila, M. K.

    2018-02-01

    Incorporation of different Alkaline earth metal like Barium, Calcium and strontium in sodium lead borate glass doped with Pr3+ is studied. Physical parameters such as density, molar volume, molar refractivity etc have been evaluated. Effect of different atomic size of alkaline metal using optical and physical parameters is analysed. XRD and FTIR were carried out to know the structural behaviour of the glasses. Absorption and Emission spectra are recorded at room temperature and the results were discussed.

  19. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  20. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu; Tian, Qiwei; Dong, Xinglong; Liu, Zhaohui; Basset, Jean-Marie; Saih, Youssef; Sun, Miao; Xu, Wei; Shaikh, Sohel

    2017-01-01

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  1. Sample preparation in alkaline media

    International Nuclear Information System (INIS)

    Nobrega, Joaquim A.; Santos, Mirian C.; Sousa, Rafael A. de; Cadore, Solange; Barnes, Ramon M.; Tatro, Mark

    2006-01-01

    The use of tetramethylammonium hydroxide, tertiary amines and strongly alkaline reagents for sample treatment involving extraction and digestion procedures is discussed in this review. The preparation of slurries is also discussed. Based on literature data, alkaline media offer a good alternative for sample preparation involving an appreciable group of analytes in different types of samples. These reagents are also successfully employed in tailored speciation procedures wherein there is a critical dependence on maintenance of chemical forms. The effects of these reagents on measurements performed using spectroanalytical techniques are discussed. Several undesirable effects on transport and atomization processes necessitate use of the method of standard additions to obtain accurate results. It is also evident that alkaline media can improve the performance of techniques such as inductively coupled plasma mass spectrometry and accessories, such as autosamplers coupled to graphite furnace atomic absorption spectrometers

  2. The cation-π interaction.

    Science.gov (United States)

    Dougherty, Dennis A

    2013-04-16

    The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

  3. Synthetic cation-selective nanotube: permeant cations chaperoned by anions.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho

    2011-01-28

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  4. Geology and petrology of Lages Alkaline District, Santa Catarina State

    International Nuclear Information System (INIS)

    Scheibe, L.F.

    1986-01-01

    A 1:100.000 geological map shows the main outcrops, covering about 50 Km 2 , of the leucocratic alkaline rocks, ultra basic alkaline rocks, carbonatites and volcanic breccias which intruded the Gondwanic sedimentary rocks within a short time interval and characterize the Alkaline District of Lages. Chemical analyses of 33 whole-rock samples confirm the petrographic classification, but the agpaitic indexes, mostly below 1.0, do not reflect the mineralogical variations of the leucocratic alkaline rocks adequately. Partial REE analyses indicate that the light as well as the heavy rare earth contents decrease from the basic to the more evolved rocks, the La/Y ratio remaining approximately constant. Eleven new K/Ar ages from porphyritic nepheline syenites porphyritic phonolites, ultra basic alkaline rocks and pipe-breccias, together with six already available ages, show a major concentration in the range 65 to 75 Ma, with a mode at ca. 70 Ma. But one Rb/Sr whole-rock reference isochron diagram gives an age of 82+-6 Ma for the agpaitic phonolites of the Serra Chapada, which are considered younger than the miaskitic porphyriric nepheline syenites. The 87 Sr/ 86 Sr ratios of 0.705-0.706 are compatible with a sub continental mantelic origin, devoid of crustal contamination. A petrogenetic model based on subtraction diagrams and taking into consideration the geologic, petrographic, mineralogic and petrochemical characteristics of the alkaline rocks of Lages consists of limited partial melting with CO 2 , contribution of the previously metasomatized upper mantle, in a region submitted to decompression. (author)

  5. Dynamics of simple defect clusters in alkaline earth fluorides

    International Nuclear Information System (INIS)

    Haridasan, T.M.; Sekar, P.

    1988-08-01

    The effect of isolated F - vacancies and interstitials on the Dobye Waller Factors of their neighbours is studied. The perturbation due to the introduction of the defect is calculated using the scattering theory. The critical jump amplitude in the diffusion process is fitted to reproduce the experimental migration energy. The diffusion coefficient for the vacancy mechanism is estimated to be larger than that for the interstitialcy mechanism in the superionic region. (author). 21 refs, 8 figs, 2 tabs

  6. Syntheses and Structural Characterization of the Alkaline Earth and ...

    Indian Academy of Sciences (India)

    dell

    checkCIF/PLATON report. You have not supplied any structure factors. As a result the full set of tests cannot be run. THIS REPORT IS FOR GUIDANCE ONLY. IF USED AS PART OF A REVIEW PROCEDURE. FOR PUBLICATION, IT SHOULD NOT REPLACE THE EXPERTISE OF AN EXPERIENCED. CRYSTALLOGRAPHIC ...

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

    International Nuclear Information System (INIS)

    Suzuki, Yasufumi; Nakajima, Kunihisa; Iwai, Takashi; Ohmichi, Toshihiko; Yamawaki, Michio.

    1995-03-01

    Complex plutonium(IV) oxides with strontium and barium, SuPuO 3 and BaPuO 3 , 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)

  8. Correlates of long-term alkaline earth retention

    International Nuclear Information System (INIS)

    Stebbings, J.H.; Schlenker, R.A.; Keane, A.T.; Kotek, T.J.; Jansen, A.J.

    1987-01-01

    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

  9. Positronium hydride defects in thermochemically reduced alkaline-Earth oxides

    International Nuclear Information System (INIS)

    Monge, M.A.; Pareja, R.; Gonzalez, R.; Chen, Y.

    1997-01-01

    Thermochemical reduction of both hydrogen-doped MgO and CaO single crystals results in large concentrations of hydride (H - ) ions. In MgO crystals, positron lifetime and Doppler broadening experiments show that positrons are trapped at H - centers forming positronium hydride molecules [e + - H - ]. A value of 640 ps is obtained for the lifetime of the PsH states located in an anion vacancy In MgO positrons are also trapped at H 2- sites at low temperatures. The H 2- ions were induced in the crystals by blue light illumination. The formation of PsH states in CaO could not be conclusively established. (orig.)

  10. Synthesis and Characterization of Some Alkaline-Earth-Oxide Nanoparticles

    Science.gov (United States)

    Singh, Jitendra Pal; Lim, Weon Cheol; Won, Sung Ok; Song, Jonghan; Chae, Keun Hwa

    2018-04-01

    The present work reports the synthesis of MgO and CaO nanoparticles by using the sol-gel autocombustion method. The annealing of the precursor at 1200 °C was observed to lead the formation of MgO nanoparticles having average crystallite size of 31 nm. Annealing the precursor at same temperature produced materials having a CaO phase with a minor impure phase of calcium carbonate ( 3%). The crystallite size corresponding to the CaO phase was 38 nm. A change of thermal history in the precursor was observed not to result in an improvement of the CaO phase. The change of thermal history in the precursor gave rise to mixed phases of CaCO3 and Ca(OH)2 rather than the phase of CaO. Further, annealing at 1200 °C for 12 h resulted in the formation of the CaO phase along with almost 1 - 5% of calcium hydroxide as an impurity phase. X-ray absorption spectroscopic measurements carried out on these materials revealed that the local electronic/atomic structure of these oxides was not only affected by the impurity phases but also influenced by the carbaneous impurities attached to the crystallites.

  11. New half-metallic materials with an alkaline earth element

    International Nuclear Information System (INIS)

    Kusakabe, Koichi; Geshi, Masaaki; Tsukamoto, Hidekazu; Suzuki, Naoshi

    2004-01-01

    New candidates for half-metallic materials were theoretically designed recently by Geshi et al. The materials are calcium pnictides, i.e. CaP, CaAs and CaSb. When the zinc-blende structure was assumed, these compounds showed half-metallic electronic band-structure, in which a curious flat band was found. To explain this magnetism, we investigated characters of orbitals on this flat band of CaAs. The hybridization of p states of As with d states of Ca is shown to be essential for formation of a flat band made of localized orbitals. The appearance of complete spin polarization in the flat band suggests that the flat-band mechanism is relevant for the ferromagnetism. A connection from the first-principles result to a solvable Hubbard model with a flat band is discussed

  12. Destructive Adsorption of Carbon Tetrachloride on Alkaline Earth Metal Oxides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Mestl, Gerhard; Rosynek, Michael P.; Krawietz, Thomas R.; Haw, James F.; Lunsford, Jack H.

    1998-01-01

    The destructive adsorption of CCl4 on MgO, CaO, SrO, and BaO has been studied as a function of the reaction temperature and the amount of CCl4 injected. The reaction was followed using in situ Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and 13 C

  13. Synthesis and infrared spectra of alkaline earth metal carbonates ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. 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.

  14. Synthesis and infrared spectra of alkaline earth metal carbonates

    Indian Academy of Sciences (India)

    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 ...

  15. Simultaneous anionic and cationic redox

    Science.gov (United States)

    Jung, Sung-Kyun; Kang, Kisuk

    2017-12-01

    It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

  16. Cation disorder in Ga1212.

    Science.gov (United States)

    Greenwood, K B; Ko, D; Vander Griend, D A; Sarjeant, G M; Milgram, J W; Garrity, E S; DeLoach, D I; Poeppelmeier, K R; Salvador, P A; Mason, T O

    2000-07-24

    Substitution of calcium for strontium in LnSr2-xCaxCu2GaO7 (Ln = La, Pr, Nd, Gd, Ho, Er, Tm, and Yb) materials at ambient pressure and 975 degrees C results in complete substitution of calcium for strontium in the lanthanum and praseodymium systems and partial substitution in the other lanthanide systems. The calcium saturation level depends on the size of the Ln cation, and in all cases, a decrease in the lattice parameters with calcium concentration was observed until a common, lower bound, average A-cation size is reached. Site occupancies from X-ray and neutron diffraction experiments for LnSr2-xCaxCu2GaO7 (x = 0 and x = 2) confirm that the A-cations distribute between the two blocking-layer sites and the active-layer site based on size. A quantitative link between cation distribution and relative site-specific cation enthalpy for calcium, strontium, and lanthanum within the gallate structure is derived. The cation distribution in other similar materials can potentially be modeled.

  17. When can ocean acidification impacts be detected from decadal alkalinity measurements?

    Science.gov (United States)

    Carter, B. R.; Frölicher, T. L.; Dunne, J. P.; Rodgers, K. B.; Slater, R. D.; Sarmiento, J. L.

    2016-04-01

    We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty.

  18. Flotation of kaolinite from tailings of kaolin-washing plants by cationic collectors

    Directory of Open Access Journals (Sweden)

    Barani Kianoush

    2016-01-01

    Full Text Available Traditional processing of kaolin is achieved by dispersion of the mined ore and classification by means of multistage hydrocyclones. The inefficiencies inherent to cyclones produce a middling product that is commonly disposed back to the quarry. In this research recovery of kaolinite from tailings of the Zonoupz kaolin washing plant, which is located in Iran, was investigated by cationic flotation. Flotation experiments showed that flotation of kaolinite from tailings was much better in an acidic than in an alkaline medium containing cationic collectors.

  19. PURIFICATION AND CHARACTERISATION OF ALKALINE ...

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    There was no clear decrease in the yield seen in the bands and the loss of enzyme was not observed with the gel analysis. It may ... The native gel results show clear distinct bands for the 3 alkaline phosphotase isoenzymes ..... British Medical.

  20. Alkaline resistant ceramics; Alkalimotstaandskraftiga keramer

    Energy Technology Data Exchange (ETDEWEB)

    Westberg, Stig-Bjoern [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2001-02-01

    Despite durability in several environments, ceramics and refractories can not endure alkaline environments at high temperature. An example of such an environment is when burning biofuel in modern heat and power plants in which the demand for increasing efficiency results in higher combustion temperatures and content of alkaline substances in the flue gas. Some experiences of these environments has been gained from such vastly different equipment as regenerator chambers in the glass industry and MHD-generators. The grains of a ceramic material are usually bonded together by a glassy phase which despite it frequently being a minor constituent render the materials properties and limits its use at elevated temperature. The damage is usually caused by alkaline containing low-melting phases and the decrease of the viscosity of the bonding glass phase which is caused by the alkaline. The surfaces which are exposed to the flue gas in a modern power plant are not only exposed to the high temperature but also a corroding and eroding, particle containing, gas flow of high velocity. The use of conventional refractory products is limited to 1300-1350 deg C. Higher strength and fracture toughness as well as durability against gases, slag and melts at temperatures exceeding 1700 deg C are expected of the materials of the future. Continuous transport of corrosive compounds to the surface and corrosion products from the surface as well as a suitable environment for the corrosion to occur in are prerequisites for extensive corrosion to come about. The highest corrosion rate is therefore found in a temperature interval between the dew point and the melting point of the alkaline-constituent containing compound. It is therefore important that the corrosion resistance is sufficient in the environment in which alkaline containing melts or slag may appear. In environments such as these, even under normal circumstances durable ceramics, such as alumina and silicon carbide, are attacked

  1. Bacterial sulphate reduction and the development of alkalinity. I. Experiments with synthetic media

    Energy Technology Data Exchange (ETDEWEB)

    Abd-El-Malek, Y; Rizk, S G

    1963-01-01

    In liquid cultures of desulphovibrio desulphuricans the effects of the following on sulphate reduction were determined: The type of cation (ca++ or na+) attached to the sulphate ion; the presence of calcium carbonate alone and with sodium chloride; the concentration of sodium sulphate, sodium lactate and sodium chloride; and the initial pH. The titratable alkalinity formed as a result of sulphate reduction was found to be quantitatively related to the sulphate reduced, and apparently unaffected by strain variation or energy source.

  2. Paleochemistry of Plio-Pleistocene Lake Turkana, Kenya. [Alkalinity

    Energy Technology Data Exchange (ETDEWEB)

    Cerling, T.

    1979-01-01

    The paleochemisry of Plio-Pleistocene Lake Turkana can be estimated by using the chemistry of lakes from the Eastern Rift of Africa as an analogue. Most modern East Africa lakes occupy closed basins; their chemistries follow an evaporation trend defined by the precipitation of certain mineral phases with increasing alkalinity. Estimates of paleoalkalinity can be used to closely estimate the chemical composition of ancient lakes. Three methods are used to estimate paleoalkalinity. Diatoms, molluscs, and fish have certain metabolic requirements that are dependent on pH, alkalinity, or calcium levels; thus fauna and flora can be used as paleoalkalinity indicators. Exchangeable cations on clay minerals can also be used because the relative concentrations of sodium and calcium in lake waters are related to alkalinity. Absence or presence of certain minerals also can serve as a paleoalkalinity indicator. Although the latter two techniques give estimates of paleoalkalinity that are averaged over several hundred or thousand years, their estimates agree with the instantaneous estimates based on biologic considerations. This study shows that the earliest lake phase was very fresh and contained until the end of the Kubi Algi Formation. The Lower Member of the Koobi Fora Formation is shown to have been a fresh- to brackish-water lake. From the beginning of Upper Member time (about 1.8 MY ago) to the present, the lake occupying the Turkana Depression has varied from a brackish lake that overflowed to a closed basin lake that fell below overflow level and whose alkalinity rose to about 200 meq/l.

  3. Qualitative Carbohydrate Analysis using Alkaline Potassium ...

    Indian Academy of Sciences (India)

    IAS Admin

    CLASSROOM. 285. RESONANCE | March 2016. Qualitative Carbohydrate Analysis using Alkaline. Potassium Ferricyanide. Keywords. Alkaline potassium ferricyanide, qualitative ... Carbohydrates form a distinct class of organic compounds often .... Laboratory Techniques: A contemporary Approach, W B Saunders Com-.

  4. Investigation of Y, FAU-zeolites containing rare earth cations

    International Nuclear Information System (INIS)

    Gardos, G.; De Jonge, A.; Halmos, F.; Kristof, J.; Redey, A.

    1984-01-01

    Polycationic zeolites were made of the H (NHsub(4))-Y, FAU form one. The change of Broensted acid sites was followed as a function of the pretreating temperature by infrared spectroscopy for mixed (La, Ce) form zeolites. It was stated that the 3630 cmsup(-1) absorption band can be related to the acidic OH-groups responsible for the catalytic activity in the alkylating reaction of isobutane with 1-butene, while the band at 3510 cmsup(-1) is characteristic of the non-acidic hydroxyl-groups and has no relation with the catalytic activity. (author)

  5. Evaluation of hydraulic conductivities of bentonite and rock under hyper alkaline and nitrate conditions (3) (Summary)

    International Nuclear Information System (INIS)

    Iriya, Keishiro; Kubo, Hiroshi

    2004-02-01

    This report is the summary of JNC-TJ--8400-2005-002. 1) Circumstance of TRU waste repository shows alkaline condition due to leaching of cementitious materials. The waste containing significant soluble nitrate may changes ground water chemistry to high ion strength. Consolidation test and permeability test are carried out in order to as. exchanged with nitrate. It is noted that permeability of bentonite increased at from 40 to 200 times by cation exchange. 2) Permeability of hyper alkaline solution is almost same to water. Permeability of hyper alkaline solution with nitrates increased corresponding to rising ion strength. 3) The results of batch of column test were simulated. The model can explain clearly the results in short period. This can estimate leaching ratio and secondary minerals. The model can simulate the experimental results by two types of velocity theory on altering bentonite. (author)

  6. Evaluation of hydraulic conductivities of bentonite and rock under hyper alkaline and nitrate conditions (3)

    International Nuclear Information System (INIS)

    Iriya, Keishiro; Kubo, Hiroshi

    2004-02-01

    Circumstance of TRU waste repository shows alkaline condition due to leaching of cementitious materials. The waste containing significant soluble nitrate may changes ground water chemistry to high ion strength. Consolidation test and permeability test are carried out in order to assess quantitatively permeability of bentonite altered by hyper alkaline and nitrate. Modeling is progressed based on experimental results. The following results are obtained. 1) Consolidation test was carried out in 3 types of bentonite and 30 % sand mixture in which cation exchanged with nitrate. It is noted that permeability of bentonite increased at from 40 to 200 times by cation exchange. 2) Permeability of hyper alkaline solution is almost same to water. Permeability of hyper alkaline solution with nitrates increased corresponding to rising ion strength. 3) The results of batch of column test were simulated. The model can explain clearly the results in short period. This can estimate leaching ratio and secondary minerals. The model can simulate the experimental results by two types of velocity theory on altering bentonite. (author)

  7. Zeolite A synthesized from alkaline assisted pre-activated halloysite for efficient heavy metal removal in polluted river water and industrial wastewater.

    Science.gov (United States)

    Meng, Qingpeng; Chen, Hong; Lin, Junzhong; Lin, Zhang; Sun, Junliang

    2017-06-01

    High quality zeolite A was synthesized through a hydrothermal process using alkaline-assisted pre-activated halloysite mineral as the alumina and silica source. The synthesis conditions employed in this study were finely tuned by varying the activating temperature, sodium hydroxide content, water content and Si/Al ratio. The obtained zeolite A showed excellent adsorption properties for both single metal cation solutions and mixed cation solutions when the concentrations of the mixed cations were comparable with those in polluted natural river water and industrial wastewater. High adsorptive capacities for Ag + (123.05mg/g) and Pb 2+ (227.70mg/g) were achieved using the synthesized zeolite A. This observation indicates that the zeolite A synthesized from alkaline-assisted pre-activated halloysite can be used as a low-cost and relatively effective adsorbent to purify heavy metal cation polluted natural river water and industrial wastewater. Copyright © 2016. Published by Elsevier B.V.

  8. Development of alkaline fuel cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  9. Iron corrosion inhibition by phosphonate complexes of rare earth metals

    International Nuclear Information System (INIS)

    Kuznetsov, Yu.I.; Raskol'nikov, A.F.; Starobinskaya, I.V.; Alekseev, V.N.

    1993-01-01

    Capability is shown of trivalent rare earth nitrilotrimethylphosphonates (R= Ce, Pr, Nd, Eu, Lu, Y) to retard steel corrosion in soft water due to the formation of slightly soluble hydroxides on steel surface. The protective film is produced as a result of electrophilic substitution of nascent iron cations for rare earth ions in near the surface layer. The introduction of rare earth cations into the protective film is ascertained by Auger spectroscopy in combination with the argon spraying. A quantitative interrelation between the protective effectiveness and solubility product of rare earth hydroxides is revealed

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

    International Nuclear Information System (INIS)

    Subba Rao, T.V.; Narayana, B.L.; Gopalan, K.

    1994-01-01

    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

  11. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd.

    Science.gov (United States)

    Duguid, J; Bloomfield, V A; Benevides, J; Thomas, G J

    1993-11-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) induce the greatest structural changes in B-DNA. The Raman (vibrational) band differences are extensive and indicate partial disordering of the B-form backbone, reduction in base stacking, reduction in base pairing, and specific metal interaction with acceptor sites on the purine (N7) and pyrimidine (N3) rings. Many of the observed spectral changes parallel those accompanying thermal denaturation of B-DNA and suggest that the metals link the bases of denatured DNA. While exocyclic carbonyls of dT, dG, and dC may stabilize metal ligation, correlation plots show that perturbations of the carbonyls are mainly a consequence of metal-induced denaturation of the double helix. Transition metal interactions with the DNA phosphates are weak in comparison to interactions with the bases, except in the case of Cu2+, which strongly perturbs both base and phosphate group vibrations. On the other hand, the Raman signature of B-DNA is largely unperturbed by Mg2+, Ca2+, Sr2+, and Ba2+, suggesting much weaker interactions of the alkaline earth metals with both base and phosphate sites. A notable exception is a moderate perturbation by alkaline earths of purine N7 sites in 160-base pair DNA, with Ca2+ causing the greatest effect. Correlation plots demonstrate a strong interrelationship between perturbations of Raman bands assigned to ring vibrations of the bases and those of bands assigned to exocyclic carbonyls and backbone phosphodiester groups. However, strong correlations do not occur between

  12. A New Alkali-Stable Phosphonium Cation Based on Fundamental Understanding of Degradation Mechanisms.

    Science.gov (United States)

    Zhang, Bingzi; Kaspar, Robert B; Gu, Shuang; Wang, Junhua; Zhuang, Zhongbin; Yan, Yushan

    2016-09-08

    Highly alkali-stable cationic groups are a critical component of hydroxide exchange membranes (HEMs). To search for such cations, we studied the degradation kinetics and mechanisms of a series of quaternary phosphonium (QP) cations. Benzyl tris(2,4,6-trimethoxyphenyl)phosphonium [BTPP-(2,4,6-MeO)] was determined to have higher alkaline stability than the benchmark cation, benzyl trimethylammonium (BTMA). A multi-step methoxy-triggered degradation mechanism for BTPP-(2,4,6-MeO) was proposed and verified. By replacing methoxy substituents with methyl groups, a superior QP cation, methyl tris(2,4,6-trimethylphenyl)phosphonium [MTPP-(2,4,6-Me)] was developed. MTPP-(2,4,6-Me) is one of the most stable cations reported to date, with <20 % degradation after 5000 h at 80 °C in a 1 m KOD in CD3 OD/D2 O (5:1 v/v) solution. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. New double-cation borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Inge; Domenech Ferrer, Roger; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, 01171 Dresden (Germany); Filinchuk, Yaroslav [Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Hagemann, Hans; Cerny, Radovan [Department of Physical Chemistry and Crystallography, University of Geneva, 1211 Geneva (Switzerland)

    2011-07-01

    Complex hydrides are under consideration for on-board hydrogen storage due to their high hydrogen density. However, up to now conventional borohydrides are either too stable or unstable for applications as in PEM fuel cells (60-120 C). Recently, double-cation borohydride systems have attracted great interest. The desorption temperature of the borohydrides decreases with increasing electronegativity of the cation. Consequently, it is possible to tailor a feasible on-board hydrogen storage material by the combination of appropriate cations. The stability was found to be intermediate between the single-cation borohydride systems. Two combinations were sucessfully synthesised by metathesis reaction via high energy ball milling. Al-Li-borohydride shows desorption at about 70 C combined with a very high hydrogen density (17.2 wt.%) and the Na-Al-borohydride (14.2 wt.%) decomposes around 90 C. Both desorption temperatures are in the target range for applications. The decomposition pathways were observed by in-situ-Raman spectroscopy, DSC (Differential Scanning Calorimetry), TG (Thermogravimetry) and thermal desorption measurements.

  14. Silica-poor, mafic alkaline lavas from ocean islands and continents

    Indian Academy of Sciences (India)

    Strongly silica-poor (ne-normative), mafic alkaline lavas generally represented by olivine nephelinites, nephelinites, melilitites, and olivine melilitites have erupted at various locations during Earth's history. On the basis of bulk-rock Mg#, high concentrations of Na2O, TiO2, and K2O, and trace element geochemistry, it has ...

  15. Methylene blue adsorption of GMZ bentonite and the effect of hyper-alkaline solution erosion

    International Nuclear Information System (INIS)

    Chen Bao; Zhang Huixin; Zhu Chunming; Chen Ping

    2012-01-01

    The method of combining the halo method with the spectrometer method, was used to study on the Methylene blue (MB) adsorption of Gaomiaozi (GMZ) bentonite, which had been eroded by hyper-alkaline solution, to investigate the mechanism of the effect of hyper-alkaline pore water on the buffer/backfill properties of GMZ bentonite. Results present, method employed in this article is brief and feasible, and high accuracy; The total specific surface area calculated by the test of MB adsorption is more accurate than the method of ethylene glycol monomethyl ether (EGIVIE). The MB adsorption of samples, which had been eroded by hyper-alkaline solution, decreases with the increase of the concentration of hyper-alkaline solution, and the change law agrees with the variation of the mass percentage of montmorillonite in bentonite tested by X- Ray diffraction (XRD). Therefore, the erosion of hyper-alkaline pore water might dissolve montmorillonite, which is the effective composition of bentonite, and destroy the tetrahedron- octahedron-tetrahedron (T-O-T) structure of montmorillonite, then lead to the decrease of cation exchange capability and the specific surface area of montmorillonite, and the the macroscopic expressions are the decrease of MB adsorption, the swelling potential and the increase of permeability. (authors)

  16. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Sohini Ganguly. Articles written in Journal of Earth System Science. Volume 119 Issue 5 October 2010 pp 675-699. Evaluation of phase chemistry and petrochemical aspects of Samchampi–Samteran differentiated alkaline complex of Mikir Hills, northeastern India.

  17. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  18. Calibration of the sodium base cation dominance index of weathering for the River Dee catchment in north-east Scotland

    Energy Technology Data Exchange (ETDEWEB)

    Stutter, M. [Aberdeen Univ. (United Kingdom). Dept. of Plant and Soil Science; Smart, R.; Cresser, M. [York Univ. (United Kingdom). Environmental Dept.

    2002-07-01

    Previously the dominance of base cations by Na{sup +} in river water in upland catchments with low weathering rates and influenced by marine-derived aerosols has been suggested as a quantitative index of weathering rate upstream of the sampling point. Using data for 59 sites from a study of the River Dee catchment in NE Scotland, the index has been fully calibrated against catchment weathering rates and net alkalinity production, derived through input output budget methods, for both upland and agricultural catchments and over a wide range of parent materials. It is shown that the relationship between Na{sup +} dominance and weathering rate is logarithmic, rather than linear as initially suggested. The excellent correlations highlight the potential use of this Na{sup +} dominance index for the direct quantification of catchment susceptibility to acidification at fine spatial resolution, using a few simple and inexpensive measurements. Stronger correlations were observed between the % Na{sup +} dominance and net annual flux of alkalinity than between % Na{sup +} dominance and weathering rate derived from summation of base cation fluxes. This demonstrates the importance of mechanisms controlling the transport of base cations out of catchments, namely in association with organic matter and with anthropogenically derived SO{sub 4}{sup 2-}. These processes are shown to reduce the residual alkalinity derived through weathering. The partial neutralization of organic acidity by internally generated alkalinity has implications in the context of using the mass balance approach for setting critical loads for catchments. (Author)

  19. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    Science.gov (United States)

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Water contentwater of determination of cationic polystyrene sulfonate resins by infrared spectrophotometry

    International Nuclear Information System (INIS)

    Noki, V.

    1987-01-01

    A method of the determination of water content in polystyrene sulfonate ion-exchange resins in the presence of alkaline earth counter-ions by I.R. spectrophotometry is proposed. This method does not hold in the case of transition metal due to the formation of coordinated complexes with water molecules.

  1. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  2. Online preconcentration ICP-MS analysis of rare earth elements in seawater

    Science.gov (United States)

    Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin

    2012-01-01

    The rare earth elements (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (˜pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix elements and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (Elemental Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline earth cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2σ) of the technique to be estimated at mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.

  3. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  4. Use of EDTA for potentiometric back titration of rare earths and analysis of their mixtures

    International Nuclear Information System (INIS)

    Zayed, M.A.; Rizk, M.S.; Khalifa, H.; Omer, W.F.

    1987-01-01

    Advantage was taken of the stoichiometric reaction between mercury(II), rare earths, alkaline earths, heavy metal ions and EDTA in urotropine buffered media to determine rare earths by back-titration of excess EDTA in the course of estimating a variety of lanthanides or analysing their binary mixture with one of the alkaline earth metals by selective control of pH; or analysing their binary mixtures with heavy metals using fluoride as a good masking agent for rare earths; or analysing their ternary mixtures with both heavy and alkaline earth metals in two steps, one by selective control of pH and the other by masking of rare earths with fluoride at lower pH to estimate the heavy metal. The procedures given are simple, rapid and extremely reliable. 19 refs. (author)

  5. Alkaline peroxide treatment of ECF bleached softwood kraft pulps: part 2. effect of increased fiber charge on refining, wet-end application, and hornification

    Science.gov (United States)

    Zheng Dang; Thomas Elder; Jeffery S. Hsieh; Arthur J. Ragauskas

    2007-01-01

    The effect of increased fiber charge on refining, cationic starch adsorption, and hornification was examined. Two pulps were investigated: (1) a softwood (SW) kraft pulp (KP) which was bleached elementally chlorine-free (ECF) and sewed as control; and (2) a control pulp treated with alkaline peroxide, which had a higher fiber charge. It was shown that increased fiber...

  6. Separation of rare earths from solutions of phosphoric acid

    International Nuclear Information System (INIS)

    Jones, E.A.

    1977-01-01

    Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

  7. Alkaline azide mutagenicity in cowpea

    Energy Technology Data Exchange (ETDEWEB)

    Mahna, S K; Bhargava, Anubha; Mohan, Lalit [Cytogenetics and Mycology Laboratory, Department of Botany, Government College, Ajmer (India)

    1990-07-01

    Sodium azide is known as a potent mutagen in cereals and legumes. It is very effective in acidic medium in barley. Here an attempt is made to measure the effectiveness of sodium azide in alkaline medium (pH 7.4) on cowpea (Vigna unguiculata (L.) Walp., variety FS-68). Seeds pre-soaked in distilled water for 5 hours were treated with different concentrations (10{sup -6}, 10{sup -5}, 10{sup -4} and 10{sup -3}M) of sodium azide (NaN{sub 3}) for 4 hours at 28{+-} 2 deg. C. Bottles were intermittently shaken, then the seeds were thoroughly washed in running tap water and subsequently planted in pots. The treatment caused significant biological damage such as reduction in seed germination, length of root and shoot, number of nodules and pods per plant and morphological leaf variations. Morphological, as well as chlorophyll mutants, were detected in M{sub 2}.

  8. Alkaline azide mutagenicity in cowpea

    International Nuclear Information System (INIS)

    Mahna, S.K.; Bhargava, Anubha; Mohan, Lalit

    1990-01-01

    Sodium azide is known as a potent mutagen in cereals and legumes. It is very effective in acidic medium in barley. Here an attempt is made to measure the effectiveness of sodium azide in alkaline medium (pH 7.4) on cowpea (Vigna unguiculata (L.) Walp., variety FS-68). Seeds pre-soaked in distilled water for 5 hours were treated with different concentrations (10 -6 , 10 -5 , 10 -4 and 10 -3 M) of sodium azide (NaN 3 ) for 4 hours at 28± 2 deg. C. Bottles were intermittently shaken, then the seeds were thoroughly washed in running tap water and subsequently planted in pots. The treatment caused significant biological damage such as reduction in seed germination, length of root and shoot, number of nodules and pods per plant and morphological leaf variations. Morphological, as well as chlorophyll mutants, were detected in M 2

  9. Environmental aspects in the processing of rare earth ores and minerals

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2011-01-01

    In India, rare earths are extracted from the mineral monazite which occurs abundantly along with other heavy minerals in the coastal beach sands. Monazite, apart from rare earths, also contains uranium and thorium. Rare earths can be obtained from monazite either by acid digestion route or by alkaline digestion route. In India, although pilot scale studies have been carried out extraction of rare earths by acid digestion route, however, alkali digestion route has been predominantly followed for commercial extraction of rare earths

  10. Constructing and Screening a Metagenomic Library of a Cold and Alkaline Extreme Environment.

    Science.gov (United States)

    Glaring, Mikkel A; Vester, Jan K; Stougaard, Peter

    2017-01-01

    Natural cold or alkaline environments are common on Earth. A rare combination of these two extremes is found in the permanently cold (less than 6 °C) and alkaline (pH above 10) ikaite columns in the Ikka Fjord in Southern Greenland. Bioprospecting efforts have established the ikaite columns as a source of bacteria and enzymes adapted to these conditions. They have also highlighted the limitations of cultivation-based methods in this extreme environment and metagenomic approaches may provide access to novel extremophilic enzymes from the uncultured majority of bacteria. Here, we describe the construction and screening of a metagenomic library of the prokaryotic community inhabiting the ikaite columns.

  11. Equilibriums of sorption of impurities of 3 d - cations by inorganic sorbents from phosphate and arsenate solutions

    International Nuclear Information System (INIS)

    Filatova, L.N.; Kurdyumova, T.N.; Bagrov, V.M.; Blyum, G.Z.

    1986-01-01

    Present article is devoted to equilibriums of sorption of impurities of 3 d - cations by inorganic sorbents from phosphate and arsenate solutions. Equilibriums of sorption of microquantities of iron, scandium, zink, copper, cobalt and manganese by inorganic sorbents on the basis of titanium and aluminium oxides from phosphate and arsenate solutions are studied. The influence of structural and chemical properties of matrix on sorption properties of oxides in phosphate and arsenate solutions is studied as well. It is defined that in concentrated solutions the sorption value of trace contaminant depends on a character of cation of alkaline metal.

  12. A radiometric method for the determination of cationic detergents with the aid of Rose Bengal labelled with 131I

    International Nuclear Information System (INIS)

    Lengyel, J.; Krtil, J.; Vecernik, J.

    1983-01-01

    A novel radiometric method for the determination of cationic detergents represented by carbetoxypentadecyltrimethylammonium bromide (Septonex) is described. The method is based on the extraction of an ion associate Septonex-Rose Bengal from an alkaline medium into chloroform. Rose Bengal labelled with 131 I ( 131 I-RB) was used as a radioreagent. The 131 I activity in the extract is proportional to the cationic detergent concentration in the solution to be analyzed. The optimum conditions for the determination of Septonex were found and the composition of the extractable complexes Rose Bengal-Septonex was determined. (author)

  13. Rare earths

    Energy Technology Data Exchange (ETDEWEB)

    Cranstone, D A

    1979-01-01

    Rare earth elements are commonly extracted from the minerals monazite, bastnaesite, and xenotine. New uses for these elements are constantly developing; they have found applications in glass polishing, television tube phosphors, high-strength low-alloy steels, magnets, catalysts, refractory ceramics, and hydrogen sponge alloys. In Canada, rare earths have been produced as byproducts of the uranium mining industry, but there was no production of rare earths in 1978 or 1979. The world sources of and markets for the rare earth elements are discussed.

  14. catalysed oxidation of atenolol by alkaline permanganate

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Kinetics of ruthenium (III) catalyzed oxidation of atenolol by permanganate in alkaline medium at constant ionic strength of 0⋅30 mol dm3 has been studied spectrophotometrically using a rapid kinetic accessory. Reaction between permanganate and atenolol in alkaline medium exhibits 1 : 8 stoichiometry.

  15. Increased liver alkaline phosphatase and aminotransferase ...

    African Journals Online (AJOL)

    The effect of daily, oral administration of ethanolic extract of Khaya senegalensis stem bark (2mg/kg body weight) for 18days on the alkaline phosphatase, aspartate and alanine aminotransferase activities of rat liver and serum were investigated. Compared with the control, the activities of liver alkaline phosphatase (ALP), ...

  16. Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

    DEFF Research Database (Denmark)

    Storm, Ida Marie Lindhardt Drejer; Rasmussen, Peter Have; Strobel, B.W.

    2008-01-01

    Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection...

  17. Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

    Indian Academy of Sciences (India)

    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 ...

  18. Purification process for aqueous solutions of rare earths by liquid-liquid extraction

    International Nuclear Information System (INIS)

    Rollat, A.; Sabot, J.L.; Burgard, M.; Delloye, T.

    1986-01-01

    Alkaline earth metals are removed by liquid-liquid extraction between on aqueous nitric phase of impure rare earth compounds and an organic phase of polyether (crown ether). This process is particularly suited to removal of Ca, Ba and Ra contained in nitric solutions of rare earths [fr

  19. Effect of illite clay and divalent cations on bitumen recovery

    Energy Technology Data Exchange (ETDEWEB)

    Ding, X. [SNC-Lavalin Inc., Calgary, AB (Canada); Repka, C. [Baker Petrolite Corp., Fort McMurray, AB (Canada); Xu, Z.; Masliyah, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2006-12-15

    Nearly 35 per cent of Canada's petroleum needs can be met from the Athabasca oil sands, particularly as conventional sources of petroleum decline. The interactions between bitumen and clay minerals play a key role in the recovery process of bitumen because they affect bitumen aeration. The 2 clays minerals found in various oil sands extraction process streams are kaolinite and illite. In this study, doping flotation tests using deionized water and electrokinetic studies were performed to examine the effect of illite clays on bitumen recovery. The effect of magnesium ions was also examined and compared with calcium ions. This paper also discussed the effects of temperature and tailings water chemistry. The negative effect of illite clay on bitumen recovery was found to be associated with its acidity. Denver flotation cell measurements indicated that the addition of calcium or magnesium ions to the flotation deionized water had only a slight effect on bitumen recovery, but the co-addition of illite clay and divalent cations resulted in a dramatic reduction in bitumen recovery. The effect was more significant at lower process temperature and low pH values. Zeta potential distributions of illite suspensions and bitumen emulsions were measured individually and as a mixture to determine the effect of divalent cations on the interaction between bitumen and illite clay. The presence of 1 mM calcium or magnesium ions in deionized water had a pronounced effect on the interactions between bitumen and illite clay. Slime coating of illite onto bitumen was not observed in zeta potential distribution measurements performed in alkaline tailings water. When tests were conducted using plant recycle water, the combination of illite clay and divalent cations did not have an adverse effect on bitumen recovery. 25 refs., 3 tabs., 15 figs.

  20. Alkaline pH sensor molecules.

    Science.gov (United States)

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range. © 2015 Wiley Periodicals, Inc.

  1. Cation-Coupled Bicarbonate Transporters

    OpenAIRE

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 ...

  2. Cation disorder in shocked orthopyroxene.

    Science.gov (United States)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  3. Cation coordination in oxychloride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J A [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Holland, D [Physics Department, Warwick University, Coventry (United Kingdom); Bland, J [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom); Johnson, C E [Physics Department, Northern Illinois University, DeKalb, IL (United States); Thomas, M F [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom)

    2003-02-19

    Glasses containing mixtures of cations and anions of nominal compositions [Sb{sub 2}O{sub 3}]{sub x} - [ZnCl{sub 2}]{sub 1-x} where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb){sub 2}(OZn)] and [Zn(ClZn){sub 2}(OSb){sub 2}].

  4. Cation coordination in oxychloride glasses

    International Nuclear Information System (INIS)

    Johnson, J A; Holland, D; Bland, J; Johnson, C E; Thomas, M F

    2003-01-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb 2 O 3 ] x - [ZnCl 2 ] 1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb) 2 (OZn)] and [Zn(ClZn) 2 (OSb) 2

  5. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  6. Electrochemical ion exchanger in the water circuit to measure cation conductivity

    International Nuclear Information System (INIS)

    Bengtsson, B.; Ingemarsson, R.; Settervik, G.; Velin, A.

    2010-01-01

    In Ringhals NPP, more than four years of successful operation with a full-scale EDI for the recycling of steam generator blow down (SGBD) gave the inspiration to modify and 'scale down' this EDI process. This with purpose to explore the possibilities to replace the cation exchanger columns used for cation conductivity analysis, with some small and integrated electrochemical ion-exchange cells. Monitoring the cation conductivity requires the use of a small cation resin column upstream of the conductivity probe and is one of the most important analyses at power plants. However, when operating with high alkaline treatment in the steam circuit, it's connected to the disadvantage of getting the resins rapidly exhausted, with needs to be frequently replaced or regenerated. This is causing interruptions in the monitoring and giving rise to high workload for the maintenance. This paper reports about some optimization and tests of two different two-compartment electrochemical cells for the possible replacements of cation resin columns when analyzing cation conductivity in the secondary steam circuit at Ringhals NPPs. Field tests during start up condition and more than four months of steady operation together with real and simulated test for impurity influences, indicates that a ELectrical Ion Echange process (ELIX) could be successfully used to replace the resin columns in Ringhals during operating with high pH-AVT (All Volatile Treatment), using hydrazine and ammonia. Installation of an ELIX-system downstream a particle filter and upstream of a small cation resin column, will introduce additional safety and further reduce the maintenance with possible interruptions. Performance of the ELIX-process together with other chemical additives (Morpholine, ETA, MPA, DMA) and dispersants, may be further evaluated to qualify the ELIX-process as well as SGBD-EDI for wider use in nuclear applications. (author)

  7. Chemically durable polymer electrolytes for solid-state alkaline water electrolysis

    Science.gov (United States)

    Park, Eun Joo; Capuano, Christopher B.; Ayers, Katherine E.; Bae, Chulsung

    2018-01-01

    Generation of high purity hydrogen using electrochemical splitting of water is one of the most promising methods for sustainable fuel production. The materials to be used as solid-state electrolytes for alkaline water electrolyzer require high thermochemical stability against hydroxide ion attack in alkaline environment during the operation of electrolysis. In this study, two quaternary ammonium-tethered aromatic polymers were synthesized and investigated for anion exchange membrane (AEM)-based alkaline water electrolyzer. The membranes properties including ion exchange capacity (IEC), water uptake, swelling degree, and anion conductivity were studied. The membranes composed of all C-C bond polymer backbones and flexible side chain terminated by cation head groups exhibited remarkably good chemical stability by maintaining structural integrity in 1 M NaOH solution at 95 °C for 60 days. Initial electrochemical performance and steady-state operation performance were evaluated, and both membranes showed a good stabilization of the cell voltage during the steady-state operation at the constant current density at 200 mA/cm2. Although both membranes in current form require improvement in mechanical stability to afford better durability in electrolysis operation, the next generation AEMs based on this report could lead to potentially viable AEM candidates which can provide high electrolysis performance under alkaline operating condition.

  8. Simulation of future stream alkalinity under changing deposition and climate scenarios

    International Nuclear Information System (INIS)

    Welsch, Daniel L.; Jack Cosby, B.; Hornberger, George M.

    2006-01-01

    Models of soil and stream water acidification have typically been applied under scenarios of changing acidic deposition, however, climate change is usually ignored. Soil air CO 2 concentrations have potential to increase as climate warms and becomes wetter, thus affecting soil and stream water chemistry by initially increasing stream alkalinity at the expense of reducing base saturation levels on soil exchange sites. We simulate this change by applying a series of physically based coupled models capable of predicting soil air CO 2 and stream water chemistry. We predict daily stream water alkalinity for a small catchment in the Virginia Blue Ridge for 60 years into the future given stochastically generated daily climate values. This is done for nine different combinations of climate and deposition. The scenarios for both climate and deposition include a static scenario, a scenario of gradual change, and a scenario of abrupt change. We find that stream water alkalinity continues to decline for all scenarios (average decrease of 14.4 μeq L - 1 ) except where climate is gradually warming and becoming more moist (average increase of 13 μeq L - 1 ). In all other scenarios, base cation removal from catchment soils is responsible for limited alkalinity increase resulting from climate change. This has implications given the extent that acidification models are used to establish policy and legislation concerning deposition and emissions

  9. Alkaline pretreatment of Mexican pine residues for bioethanol ...

    African Journals Online (AJOL)

    Alkaline pretreatment of Mexican pine residues for bioethanol production. ... Keywords: Lignocellulosic biomass, alkaline pretreatment, enzymatic hydrolysis, fermentable sugars, fermentation. African Journal of Biotechnology Vol. 12(31), pp.

  10. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    Science.gov (United States)

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  11. Electronic spectra of astrophysically interesting cations

    Energy Technology Data Exchange (ETDEWEB)

    Maier, John P., E-mail: j.p.maier@unibas.ch; Rice, Corey A., E-mail: j.p.maier@unibas.ch; Mazzotti, Fabio J., E-mail: j.p.maier@unibas.ch; Johnson, Anatoly, E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstr. 80, CH-4056 Basel (Switzerland)

    2015-01-22

    The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ∼506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

  12. Alkaline rocks and the occurrence of uranium

    International Nuclear Information System (INIS)

    Hambleton-Jones, B.B.; Toens, P.D.

    1980-10-01

    Many alkaline complexes contain uranium and other minerals in low concentrations and are regarded as constituting valuable potential reserves. Certain complex metallurgical problems, however, remain to be solved. Alkaline rocks occur in a number of forms and environments and it is noted that they are generated during periods of geological quiescence emplaced mainly in stable aseismic areas. Many occur along the extensions of oceanic transform faults beneath the continental crust and the application of this concept to areas not currently known to host alkaline complexes may prove useful in identifying potential target areas for prospecting operations [af

  13. Uranium isotope separation using styrene cation exchangers

    International Nuclear Information System (INIS)

    Kahovec, J.

    1980-01-01

    The separation of 235 U and 238 U isotopes is carried out either by simple isotope exchange in the system uranium-cation exchanger (sulphonated styrene divinylbenzene resin), or by combination of isotope exchange in a uranium-cation exchanger (Dowex 50, Amberlite IR-120) system and a chemical reaction. A review is presented of elution agents used, the degree of cation exchanger cross-linking, columns length, and 235 U enrichment. The results are described of the isotope effect study in a U(IV)-U(VI)-cation exchanger system conducted by Japanese and Romanian authors (isotope exchange kinetics, frontal analysis, reverse (indirect) frontal analysis). (H.S.)

  14. Cation-π interactions in structural biology

    OpenAIRE

    Gallivan, Justin P.; Dougherty, Dennis A.

    1999-01-01

    Cation-pi interactions in protein structures are identified and evaluated by using an energy-based criterion for selecting significant sidechain pairs. Cation-pi interactions are found to be common among structures in the Protein Data Bank, and it is clearly demonstrated that, when a cationic sidechain (Lys or Arg) is near an aromatic sidechain (Phe, Tyr, or Trp), the geometry is biased toward one that would experience a favorable cation-pi interaction. The sidechain of Arg is more likely tha...

  15. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  16. Chromatographic separation of metal cations on silica gel chemically modified with a polymeric derivative of diaza-18-crown-6

    International Nuclear Information System (INIS)

    Basyuk, V.A.

    1991-01-01

    Sorbent on the basis of γ-aminopropyl silica gel, containing chemically grafted polymer derivatives of diaza-18-crown-6, has been synthesized. Retaining of certain metal cations when acid mobile phases are used is studied. Acetate buffer solution, 0.005% aqueous solution of acetic acid and 10 mM aqueous solution of oxalic acid were used as mobile phases. Rare earth cations (including Sr 2+ ones) are weakly retained when any mobile phase is used. Retention of VO 2+ cations is the strongest one

  17. Anodic solution of alkali earth alloys in potassium chloride-sodium chloride melts

    International Nuclear Information System (INIS)

    Volkovich, A.V.

    1997-01-01

    Generalized results of studying the process of anodic dissolution of alkaline-earth metal alloys with zinc, aluminium and copper in the melts of KCl-NaCl equimolar mixture containing alkaline-earth metal chlorides, are presented. It is shown that during dissolution of both pure liquid metals and their alloys there is no electrode polarization in the range of the current densities lower or comparable in their values to corrosion current

  18. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  19. Earth Rotation

    Science.gov (United States)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  20. Phenolic cation exchange resin material for recovery of cesium and strontium

    Science.gov (United States)

    Ebra, Martha A.; Wallace, Richard M.

    1983-01-01

    A phenolic cation exchange resin with a chelating group has been prepared by reacting resorcinol with iminodiacetic acid in the presence of formaldehyde at a molar ratio of about 1:1:6. The material is highly selective for the simultaneous recovery of both cesium and strontium from aqueous alkaline solutions, such as, aqueous alkaline nuclear waste solutions. The organic resins are condensation polymers of resorcinol and formaldehyde with attached chelating groups. The column performance of the resins compares favorably with that of commercially available resins for either cesium or strontium removal. By combining Cs.sup.+ and Sr.sup.2+ removal in the same bed, the resins allow significant reduction of the size and complexity of facilities for processing nuclear waste.

  1. Phenolic cation-exchange resin material for recovery of cesium and strontium. [Patent application

    Science.gov (United States)

    Ebra, M.A.; Wallace, R.M.

    1982-05-05

    A phenolic cation exchange resin with a chelating group has been prepared by reacting resorcinol with iminodiacetic acid in the presence of formaldehyde at a molar ratio of about 1:1:6. The material is highly selective for the simultaneous recovery of both cesium and strontium from aqueous alkaline solutions, such as, aqueous alkaline nuclear wate solutions. The organic resins are condensation polymers of resorcinol and formaldehyde with attached chelating groups. The column performance of the resins compares favorably with that of commercially available resins for either cesium or strontium removal. By combining Cs/sup +/ and Sr/sup 2 +/ removal in the same bed, the resins allow significant reduction of the size and complexity of facilities for processing nuclear waste.

  2. Alkalinity in oil field waters - what alkalinity is and how it is measured

    International Nuclear Information System (INIS)

    Kaasa, B.; Oestvold, T.

    1996-01-01

    The alkalinity is an important parameter in the description of pH-behaviour, buffer capacity and scaling potentials in oil field waters. Although the alkalinity is widely used, it seems to be considerable confusion in connection with the concept. It is often used incorrectly and different authors define the concept in different ways. Several different methods for the determination of alkalinity can be found in the literature. This paper discusses the definition of alkalinity and how to use alkalinity in oil field waters to obtain data of importance for scale and pH predictions. There is also shown how a simple titration of oil field waters can give both the alkalinity and the content of organic acids in these waters. It is obvious from these findings that most of the methods used to day may give considerable errors when applied to oil field waters with high contents of organic acids. 8 refs., 8 figs., 5 tabs

  3. Comparative study of the ionic exchange of Ca{sup ++}, Sr{sup ++}, and Ba{sup ++} cations on resins and inorganic exchangers; Etude comparative de l'echange ionique des cations Ca{sup ++}, Sr{sup ++} et Ba{sup ++} sur resine et sur echangeurs mineraux

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Batanero, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-03-01

    With a view to applying the results to certain problems related to chemical separations in activation analysis, a study has been made, of the possibilities of separating the alkaline-earth elements Ca, Sr and Ba on organic resins and inorganic exchangers using the radioactive indicator method. The partition coefficients of the cations Ca{sup 2+}, Sr{sup 2+} and Ba{sup 2+} have been measured on Dowex 50 W (NH{sub 4}{sup +}) x 8 resin in the presence of EDTA - NTA - EGTA and DCTA as complexing agents, and on zirconium phosphate, tungstate and molybdate in the presence of HCl and NH{sub 4}Cl. Methods have been developed for separating mixtures of alkaline-earth elements using DCTA-NH{sub 4}{sup +} followed by elution on Dowex 50 W (NH{sub 4}{sup +}) x 8 resin columns and on zirconium phosphate. Amongst the complexing agents used on the ion-exchange resins the most promising appears to be DCTA which leads to partition coefficients Ca, Sr and Ba which are very different. The results of measurements of partition coefficients on zirconium phosphate (NH{sub 4}{sup +} form) using DCTA-NH{sub 4}{sup +} show the interesting possibilities of separations on columns. The separation of the alkaline-earth elements on zirconium phosphate seems to be less quantitative than on Dowex 50 resin; it is however much faster in the former case and this can be useful for treating short half-life radioisotopes in activation analysis. (author) [French] En vue de l'application a certains problemes de separations chimiques en analyse par activation, on a etudie les possibilites de separation des elements alcalino-terreux Ca-Sr et Ba sur resine organique et sur echangeurs mineraux par la methode des indicateurs radioactifs. Les coefficients de partage des cations Ca{sup +2}, Sr{sup +2} et Ba{sup +2} sur resine Dowex 50 W (NH{sub 4}{sup +}) x 8 en milieux complexants EDTA - NTA - EGTA et DCTA et sur phosphate, tungstate et molybdate de zirconium en milieu HCl et NH{sub 4}Cl ont ete mesures. Des

  4. Technetium recovery from high alkaline solution

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Charles A.

    2016-07-12

    Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

  5. Real-time materials evolution visualized within intact cycling alkaline batteries

    Energy Technology Data Exchange (ETDEWEB)

    Gallaway, JW; Erdonmez, CK; Zhong, Z; Croft, M; Sviridov, LA; Sholklapper, TZ; Turney, DE; Banerjee, S; Steingart, DA

    2014-01-01

    The scientific community has focused on the problem of inexpensive, safe, and sustainable large-scale electrical energy storage, which is needed for a number of emerging societal reasons such as stabilizing intermittent renewables-based generation like solar and wind power. The materials used for large-scale storage will need to be low cost, earth-abundant, and safe at the desired scale. The Zn-MnO2 "alkaline" battery chemistry is associated with one-time use, despite being rechargeable. This is due to material irreversibilities that can be triggered in either the anode or cathode. However, as Zn and MnO2 have high energy density and low cost, they are economically attractive even at limited depth of discharge. As received, a standard bobbin-type alkaline cell costs roughly $20 per kW h. The U. S. Department of Energy ARPA-E $100 per kW h cost target for grid storage is thus close to the cost of alkaline consumer primary cells if re-engineered and/or cycled at 5-20% nominal capacity. Herein we use a deeply-penetrating in situ technique to observe ZnO precipitation near the separator in an alkaline cell anode cycled at 5% DOD, which is consistent with cell failures observed at high cycle life. Alkaline cells designed to avoid such causes of cell failure could serve as a low-cost baseload for large-scale storage.

  6. Petrology, geochemistry and source characteristics of the Burpala alkaline massif, North Baikal

    Directory of Open Access Journals (Sweden)

    N.V. Vladykin

    2017-07-01

    Full Text Available The Burpala alkaline massif contains rocks with more than 50 minerals rich in Zr, Nb, Ti, Th, Be and rare earth elements (REE. The rocks vary in composition from shonkinite, melanocratic syenite, nepheline and alkali syenites to alaskite and alkali granite and contain up to 10% LILE and HSFE, 3.6% of REE and varying amounts of other trace elements (4% Zr, 0.5% Y, 0.5% Nb, 0.5% Th and 0.1% U. Geological and geochemical data suggest that all the rocks in the Burpala massif were derived from alkaline magma enriched in rare earth elements. The extreme products of magma fractionation are REE rich pegmatites, apatite–fluorite bearing rocks and carbonatites. The Sr and Nd isotope data suggest that the source of primary melt is enriched mantle (EM-II. We correlate the massif to mantle plume impact on the active margin of the Siberian continent.

  7. Cationic polymers and their therapeutic potential

    NARCIS (Netherlands)

    Samal, S.K.; Dash, M.; van Vlierberghe, S.; Kaplan, D.; Chiellini, E.; van Blitterswijk, Clemens; Moroni, Lorenzo; Dubruel, P.

    2012-01-01

    The last decade has witnessed enormous research focused on cationic polymers. Cationic polymers are the subject of intense research as non-viral gene delivery systems, due to their flexible properties, facile synthesis, robustness and proven gene delivery efficiency. Here, we review the most recent

  8. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  9. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope of the...

  10. Structural and energetic study of cation-π-cation interactions in proteins.

    Science.gov (United States)

    Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

    2017-04-12

    Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

  11. The effect of drains on the alkalinity of agricultural soils

    International Nuclear Information System (INIS)

    Iqbal, M.A.; Butt, T.; Anwar-ul-Haque; Haroon, M.; Haq, I.U.

    2009-01-01

    The purpose of the study was to observe the effect of industrial and domestic drains on the nearby agricultural areas which are either irrigated or not by the waste water but are close to drains. For this purpose 48 soil samples were collected from the selected areas of Faisalabad and were analyzed for alkali metals like Na/sup +/, K/sup +/, Li/sup +/ and some alkaline earth metals like Ba/sup 2+/> Mg/sup 3+/> Na/sup +/> K/sup +/> Li/sup +/ the levels of Ba/sup +2/ and K/sup +/ were found higher than permissible levels in almost all the soil samples. It was also concluded that the agricultural areas near the industrial drain which are either irrigated or not by the industrial waste water are found highly contaminated with mobile alkali metals (K, Na etc.) and higher values of percentage salinity. (author)

  12. A Cation-containing Polymer Anion Exchange Membrane based on Poly(norbornene)

    Science.gov (United States)

    Beyer, Frederick; Price, Samuel; Ren, Xiaoming; Savage, Alice

    Cation-containing polymers are being studied widely for use as anion exchange membranes (AEMs) in alkaline fuel cells (AFCs) because AEMs offer a number of potential benefits including allowing a solid state device and elimination of the carbonate poisoning problem. The successful AEM will combine high performance from several orthogonal properties, having robust mechanical strength even when wet, high hydroxide conductivity, and the high chemical stability required for long device lifetimes. In this study, we have synthesized a model cationic polymer that combines three of the key advantages of Nafion. The polymer backbone based on semicrystalline atactic poly(norbornene) offers good mechanical properties. A flexible, ether-based tether between the backbone and fixed cation charged species (quaternary ammonium) should provide the low-Tg, hydrophilic environment required to facilitate OH- transport. Finally, methyl groups have been added at the beta position relative to the quaternary ammonium cation to prevent Hoffman elimination, one mechanism by which AEMs are neutralized in a high pH environment. In this poster, we will present our findings on mechanical properties, morphology, charge transport, and chemical stability of this material.

  13. Improved electrodes and gas impurity investigations on alkaline electrolysers

    DEFF Research Database (Denmark)

    Reissner, R.; Schiller, G.; Knoeri, T.

    Alkaline water electrolysis for hydrogenproduction is a well-established techniquebut some technological issues regarding thecoupling of alkaline water electrolysis andRenewable Energy Sources (RES) remain tobe improved.......Alkaline water electrolysis for hydrogenproduction is a well-established techniquebut some technological issues regarding thecoupling of alkaline water electrolysis andRenewable Energy Sources (RES) remain tobe improved....

  14. (Cationic + nonionic) mixed surfactant aggregates for solubilisation of curcumin

    International Nuclear Information System (INIS)

    Kumar, Arun; Kaur, Gurpreet; Kansal, S.K.; Chaudhary, G.R.; Mehta, S.K.

    2016-01-01

    Highlights: • Critical micelle concentration of mixed surfactant has been measured. • Aqueous solubility and alkaline stability of curcumin has been significantly improved. • Location of curcumin within micelles has been evaluated. • Scavenging activity of curcumin has been improved. • Non-intercalative binding with ct-DNA has been observed. - Abstract: Curcumin is a potential drug for variety of diseases. Major limitations of curcumin are low water solubility, rapid hydrolytic degradation in alkaline medium and poor bioavailability. To overcome these limitations, highly potential mixed micellar system has been prepared. In order to reduce inter ionic repulsion and precipitation of surfactants, (cationic + non-ionic) mixed system have been chosen that directly influence its applicability. Hydrophobic chain of non-ionic surfactant significantly influences the cmc of mixed surfactant system as indicated by fluorescence and conductivity data. UV–visible spectroscopy analyses show that solubility, stability and antioxidant property of the curcumin is remarkably improved depending on cmc and aggregation number (N_a_g_g) of mixed surfactants, where N_a_g_g plays crucial role. Generally, curcumin undergoes complete degradation in slight basic medium, but stability has been maintained up to 8 h at pH-13 using formulated mixed micelles (only (20 to 25)% degraded). Location of curcumin which is monitored using emission spectroscopy, fluorescence quenching and "1H NMR spectroscopy techniques play the most important role. Observed results show that the major population of curcumin is located at the polar region and some are in hydrophobic region of the mixed micelles. To ensure the effect of mixed surfactants and curcumin loaded mixed surfactants on DNA, the interaction parameter indicates non-interclative interactions.

  15. Electrochemical Studies for Cation Recognition with Diazo-Coupled Calix[4]arenes

    Directory of Open Access Journals (Sweden)

    Bongsu Kim

    2015-01-01

    Full Text Available The electrochemical properties of diazophenylcalix[4]arenes bearing ortho-carboxyl group (o-CAC and ortho-ester group (o-EAC, respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN. o-CAC and o-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However, o-CAC preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in voltammetric signals are observed in o-EAC with alkaline earth metal ions. o-EAC only binds with other transition metal ions. This can be explained on metal ion complexation-induced release of proton from the azophenol to the quinone-hydrazone tautomer followed by internal complexation of the metal ion with aid of nitrogen atoms and ortho-carbonyl groups in the diazophenylazocalix[4]arenes.

  16. Electrochemistry of Pt (100) in alkaline media: A voltammetric study

    Science.gov (United States)

    van der Vliet, Dennis F.; Koper, Marc T. M.

    2010-10-01

    Pt (100) is one of the fcc metal surface planes that reconstruct upon annealing at high temperatures. The state of the surface is important in electrochemistry, in order to correlate catalytic behavior with surface structure. Therefore, the behavior of single crystalline Pt (100) in alkaline media was investigated, with particular attention paid to surface long-range order. It was found that, in line with previous results, the manner of cooling the crystal after annealing influenced the state of surface significantly, with a profound effect on blank cyclic voltammetry as well as on carbon monoxide oxidation. Different ratios of inert and reductive gases were used to see if an optimal mixture could be obtained. Using air, argon, hydrogen, CO, and combinations of these gases gave rise to different states of the surface, with clear observable differences in blank voltammetric behavior and CO stripping. Also, the effect of alkali-metal cations and bromide on the blank and CO stripping voltammetry was investigated. Our main conclusion is that cooling in a carbon monoxide containing gas gives a clean, almost defect-free surface with long-range 1 × 1 symmetry. A similar surface can also be prepared with a hydrogen-containing cooling gas, but the content of hydrogen in that stream is critical.

  17. Cation transport in isomeric pentanes

    International Nuclear Information System (INIS)

    Gyoergy, Istvan; Gee, Norman; Freeman, G.R.

    1985-01-01

    The cation mobility μsub(+) is measured in n-pentane, isopentane, neo-pentane, and mixtures of n- and neo-pentane over conditions from the normal liquid, through the critical fluid, to the low density gas. Most of the liquid data correlate with the reduced temperature T/Tsub(c). The T/Tsub(c) reflects free volume and viscosity changes. Comparison is made to neutral molecule diffusion. The transition from viscosity control of mobility in the liquid to density control in the dilute gas occurs over the reduced viscosity region 3 > eta/etasub(c) > 0.6, which corresponds to the reduced density region 1.9 > eta/etasub(c) > 0.5. In the saturated gas etaμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average gas nμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average momentum transfer cross sections in the n-/neo-pentane mixtures are similar to those in neo-pentane at low T but similar to those in n-pentane at high T. The present findings are combined with previous electron mobility data in addressing the effect of hydrocarbon molecular (external) shape on the electric breakdown strength of gases

  18. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  19. Stressor states and the cation crossroads.

    Science.gov (United States)

    Weber, Karl T; Bhattacharya, Syamal K; Newman, Kevin P; Soberman, Judith E; Ramanathan, Kodangudi B; McGee, Jesse E; Malik, Kafait U; Hickerson, William L

    2010-12-01

    Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.

  20. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  1. Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

    Science.gov (United States)

    Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

    2018-01-01

    Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

  2. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  3. Radioimmunoassay of human eosinophil cationic protein

    International Nuclear Information System (INIS)

    Venge, P.; Roxin, L.E.; Olsson, I.

    1977-01-01

    A radioimmunosorbent assay has been developed which allows the detection in serum of a cationic protein derived from eosinophil granulocytes. In 34 healthy individuals the mean level was 31 μg/l. with a range of 5 to 55 μg/l. The serum concentration of 'eosinophil' cationic protein was correlated (P<0.001) to the number of eosinophil granulocytes in peripheral blood. Quantitiation of 'eosinophil' cationic protein in serum might be useful in the study of eosinophil granulocyte turnover and function in vivo. (author)

  4. Determination of the cation exchange capacity of bentonite exposed to hyperalkaline fluid

    Energy Technology Data Exchange (ETDEWEB)

    Calabria, Jaqueline A.A.; Amaral, Daniela N. do; Ladeira, Ana Claudia Q.; Cota, Stela D.S.; Silva, Talita S.S., E-mail: jaalmeida@cdtn.br, E-mail: danielanogueir@gmail.com, E-mail: acql@cdtn.br, E-mail: sdsc@cdtn.br, E-mail: tsss@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The hyper alkaline fluid that could be generated by cementitious degradation in a repository, can affect important properties of backfilling materials, host-rocks and soils. It is well known that mineralogical characteristics of materials can change with the exposition to high pH conditions, such as found in a disposal installation. These modifications are likely to cause deterioration in physical and chemical properties of these materials, e.g., hydraulic conductivity, radionuclides sorption (Kd), diffusivity and cation exchange capacity (CEC). This paper presents the preliminary results for bentonite exposed to alkaline solutions in order to establish the time for mineralogical modifications to occur. The property of bentonite used as an indicator of the modification was CEC. A commercial bentonite was treated with NaOH 1 mol/L at 30 deg C, for different periods of time that varied from 4 hours to 28 days. After that, the CEC was determined by the conventional methylene-blue adsorption titration method. Although the methylene-blue titration has given fast results, it has not demonstrated confidence, due to the semi-quantitative nature of this technique. Generally, the values of CEC decreased from 68 meq/100g to 42 meq/100g with the time of contact showing that hyper alkaline conditions provide significant changes in the CEC. Additionally, a second group of samples was modified with moderate alkaline solution and had the CEC determined by Centrifuge Method, reported in Soil Survey Laboratory Methods Manual, number 42. The second group presented an increase in the CEC in few hours of alteration, which can be explained by the formation of zeolites when an alkaline solution containing K and Ca is used. (author)

  5. Determination of the cation exchange capacity of bentonite exposed to hyperalkaline fluid

    International Nuclear Information System (INIS)

    Calabria, Jaqueline A.A.; Amaral, Daniela N. do; Ladeira, Ana Claudia Q.; Cota, Stela D.S.; Silva, Talita S.S.

    2013-01-01

    The hyper alkaline fluid that could be generated by cementitious degradation in a repository, can affect important properties of backfilling materials, host-rocks and soils. It is well known that mineralogical characteristics of materials can change with the exposition to high pH conditions, such as found in a disposal installation. These modifications are likely to cause deterioration in physical and chemical properties of these materials, e.g., hydraulic conductivity, radionuclides sorption (Kd), diffusivity and cation exchange capacity (CEC). This paper presents the preliminary results for bentonite exposed to alkaline solutions in order to establish the time for mineralogical modifications to occur. The property of bentonite used as an indicator of the modification was CEC. A commercial bentonite was treated with NaOH 1 mol/L at 30 deg C, for different periods of time that varied from 4 hours to 28 days. After that, the CEC was determined by the conventional methylene-blue adsorption titration method. Although the methylene-blue titration has given fast results, it has not demonstrated confidence, due to the semi-quantitative nature of this technique. Generally, the values of CEC decreased from 68 meq/100g to 42 meq/100g with the time of contact showing that hyper alkaline conditions provide significant changes in the CEC. Additionally, a second group of samples was modified with moderate alkaline solution and had the CEC determined by Centrifuge Method, reported in Soil Survey Laboratory Methods Manual, number 42. The second group presented an increase in the CEC in few hours of alteration, which can be explained by the formation of zeolites when an alkaline solution containing K and Ca is used. (author)

  6. Mineralogy of the rare earth elements

    International Nuclear Information System (INIS)

    Clark, A.M.

    1984-01-01

    This paper contains mineralogic properties of the rare earth elements (REE). Notes are given on total REE abundances, distribution patterns, and modes of occurrence. References are confined as far as possible to papers containing usable REE data. The minerals are grouped alphabetically within each major cationic group. The paper includes an alphabetic table of mineral names, chemical formulas, crystal system and section number. It functions as a handy entrance to the mineralogic and bibliographic paper. (G.J.P.)

  7. Assessing ocean alkalinity for carbon sequestration

    Science.gov (United States)

    Renforth, Phil; Henderson, Gideon

    2017-09-01

    Over the coming century humanity may need to find reservoirs to store several trillions of tons of carbon dioxide (CO2) emitted from fossil fuel combustion, which would otherwise cause dangerous climate change if it were left in the atmosphere. Carbon storage in the ocean as bicarbonate ions (by increasing ocean alkalinity) has received very little attention. Yet recent work suggests sufficient capacity to sequester copious quantities of CO2. It may be possible to sequester hundreds of billions to trillions of tons of C without surpassing postindustrial average carbonate saturation states in the surface ocean. When globally distributed, the impact of elevated alkalinity is potentially small and may help ameliorate the effects of ocean acidification. However, the local impact around addition sites may be more acute but is specific to the mineral and technology. The alkalinity of the ocean increases naturally because of rock weathering in which >1.5 mol of carbon are removed from the atmosphere for every mole of magnesium or calcium dissolved from silicate minerals (e.g., wollastonite, olivine, and anorthite) and 0.5 mol for carbonate minerals (e.g., calcite and dolomite). These processes are responsible for naturally sequestering 0.5 billion tons of CO2 per year. Alkalinity is reduced in the ocean through carbonate mineral precipitation, which is almost exclusively formed from biological activity. Most of the previous work on the biological response to changes in carbonate chemistry have focused on acidifying conditions. More research is required to understand carbonate precipitation at elevated alkalinity to constrain the longevity of carbon storage. A range of technologies have been proposed to increase ocean alkalinity (accelerated weathering of limestone, enhanced weathering, electrochemical promoted weathering, and ocean liming), the cost of which may be comparable to alternative carbon sequestration proposals (e.g., $20-100 tCO2-1). There are still many

  8. Posttranslational heterogeneity of bone alkaline phosphatase in metabolic bone disease.

    Science.gov (United States)

    Langlois, M R; Delanghe, J R; Kaufman, J M; De Buyzere, M L; Van Hoecke, M J; Leroux-Roels, G G

    1994-09-01

    Bone alkaline phosphatase is a marker of osteoblast activity. In order to study the posttranscriptional modification (glycosylation) of bone alkaline phosphatase in bone disease, we investigated the relationship between mass and catalytic activity of bone alkaline phosphatase in patients with osteoporosis and hyperthyroidism. Serum bone alkaline phosphatase activity was measured after lectin precipitation using the Iso-ALP test kit. Mass concentration of bone alkaline phosphatase was determined with an immunoradiometric assay (Tandem-R Ostase). In general, serum bone alkaline phosphatase mass and activity concentration correlated well. The activity : mass ratio of bone alkaline phosphatase was low in hyperthyroidism. Activation energy of the reaction catalysed by bone alkaline phosphatase was high in osteoporosis and in hyperthyroidism. Experiments with neuraminidase digestion further demonstrated that the thermodynamic heterogeneity of bone alkaline phosphatase can be explained by a different glycosylation of the enzyme.

  9. Urbanization accelerates long-term salinization and alkalinization of fresh water

    Science.gov (United States)

    Kaushal, S.; Duan, S.; Doody, T.; Haq, S.; Smith, R. M.; Newcomer Johnson, T. A.; Delaney Newcomb, K.; Gorman, J. K.; Bowman, N.; Mayer, P. M.; Wood, K. L.; Belt, K.; Stack, W.

    2017-12-01

    Human dominated land-use increases transport a major ions in streams due to anthropogenic salts and accelerated weathering. We show long-term trends in calcium, magnesium, sodium, alkalinity, and hardness over 50 years in the Baltimore metropolitan region and elsewhere. We also examine how major ion concentrations have increased significantly with impervious surface cover in watersheds across land use. Base cations show strong relationships with acid anions, which illustrates the coupling of major biogeochemical cycles in urban watersheds over time. Longitudinal patterns in major ions can also show increasing trends from headwaters to coastal waters, which suggests coupled biogeochemical cycles over space. We present new results from manipulative experiments and long-term monitoring across different urban regions regarding patterns and processes of salinization and alkalinization. Overall, our work demonstrates that urbanization dramatically increases major ions, ionic strength, and pH over decades from headwaters to coastal waters, which impacts the integrity of aquatic life, infrastructure, drinking water, and coastal ocean alkalinization.

  10. Cationization of heparin for film applications

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.

    2015-01-01

    Roč. 115, 22 January (2015), s. 551-558 ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.219, year: 2015

  11. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

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

    2013-01-01

    Alkaline electrolyzers have proven to operate reliable for decades on a large scale, but in order to become commercially attractive and compete against conventional technologies for hydrogen production, the production and investment costs have to be reduced. This may occur by increasing the opera......Alkaline electrolyzers have proven to operate reliable for decades on a large scale, but in order to become commercially attractive and compete against conventional technologies for hydrogen production, the production and investment costs have to be reduced. This may occur by increasing...

  12. Catalytic oxidation of soot over alkaline niobates

    International Nuclear Information System (INIS)

    Pecchi, G.; Cabrera, B.; Buljan, A.; Delgado, E.J.; Gordon, A.L.; Jimenez, R.

    2013-01-01

    Highlights: ► No previous reported studies about alkaline niobates as catalysts for soot oxidation. ► NaNbO 3 and KNbO 3 perovskite-type oxides show lower activation energy than other lanthanoid perovskite-type oxides. ► The alkaline niobate does not show deactivation by metal loss. - Abstract: The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N 2 adsorption, XRD, O 2 -TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO 3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO 3 > NaNbO 3 > LiNbO 3 . The RbNbO 3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO 3 , despite the lower apparent activation energy of NaNbO 3 , stress the importance of the metal nature and suggests the hypothesis that K + ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.

  13. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  14. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  15. Chemical reactivity of cation-exchanged zeolites

    OpenAIRE

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed by Brønsted acid sites in the hydrogen forms of zeolites, the nature of chemical reactivity, and related, the structure of the metal-containing ions in cation-exchanged zeolites remains the subject...

  16. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 5 ... They are mainly of high-K calc-alkaline series with indistinct Eu anomalies, enriched in ... School of Geosciences and Info-Physics, Central South University, Changsha ...

  17. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 110; Issue 3. Volume 110, Issue 3. September 2001, pages 185-265. pp 185-190. Ar-Ar age of carbonatite-alkaline magmatism in Sung Valley, Maghalaya, India · Jyotiranjan S Ray Kanchan Pande · More Details Abstract Fulltext PDF. 40Ar-39Ar analyses of one ...

  18. Mineralogical, petrological and geochemical aspects of alkaline and alkaline-carbonatite associations from Brazil

    Science.gov (United States)

    Morbidelli, L.; Gomes, C. B.; Beccaluva, L.; Brotzu, P.; Conte, A. M.; Ruberti, E.; Traversa, G.

    1995-12-01

    A general description of Mesozoic and Tertiary (Fortaleza) Brazilian alkaline and alkaline-carbonatite districts is presented with reference to mineralogy, petrology, geochemistry and geochronology. It mainly refers to scientific results obtained during the last decade by an Italo-Brazilian research team. Alkaline occurrences are distributed across Brazilian territory from the southern (Piratini, Rio Grande do Sul State) to the northeastern (Fortaleza, Ceará State) regions and are mainly concentrated along the borders of the Paraná Basin generally coinciding with important tectonic lineaments. The most noteworthy characteristics of these alkaline and alkaline-carbonatite suites are: (i) prevalence of intrusive forms; (ii) abundance of cumulate assemblages (minor dunites, frequent clinopyroxenites and members of the ijolite series) and (iii) abundance of evolved rock-types. Many data demonstrate that crystal fractionation was the main process responsible for magma evolution of all Brazilian alkaline rocks. A hypothesis is proposed for the genesis of carbonatite liquids by immiscibility processes. The incidence of REE and trace elements for different major groups of lithotypes, belonging both to carbonatite-bearing and carbonatite-free districts, are documented. Sr and preliminary Nd isotopic data are indicative of a mantle origin for the least evolved magmas of all the studied occurrences. Mantle source material and melting models for the generation of the Brazilian alkaline magma types are also discussed.

  19. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Science.gov (United States)

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J A; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+), Ca(2+) or Na(+), respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>2 h) than deprotonation of functional groups (cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for CaB and aging-induced structural reorganisation can enhance cross-link formation.

  20. Earth thermics

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, M

    1960-01-01

    The thermodynamics of the Earth are described, including terrestrial heat flow, internal temperatures and thermal history. The value of the geothermal gradient has been considered to be 3/sup 0/C/100 m but measured values are slightly different. The values of terrestrial heat flow are relatively constant and are calculated be about 2.3 x 10 to the minus 6 cal/cm/sup 2/ sec (2.3 HFU). The Earth's internal temperature can be calculated from the adiabatic temperature gradient of adiabatic expansion. Using Simon's equation No. 9, a value of 2100-2500/sup 0/C is obtained, this is much lower than it was previously thought to be. The value of 2.3 HFU can easily be obtained from this internal temperature figure.

  1. Indirect spectrophotometric determination of trace cyanide with cationic porphyrins.

    Science.gov (United States)

    Ishii, H; Kohata, K

    1991-05-01

    Three highly sensitive methods for the determination of cyanide have been developed, based on the fact that the complexation of silver ions with three cationic porphyrins, 5,10,15,20-tetrakis-(1-methyl-2-pyridinio)porphine [T(2-MPy)P], 5,10,15,20-tetrakis(1-methyl-3-pyridinio)porphine [T(3-MPy)P] and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphine [T(4-MPy)P], in alkaline media is inhibited by cyanide and the decrease in absorbance of the silver(II) complex is proportional to the cyanide concentration. Sensitivities of the procedures developed are 0.133, 0.126 and 0.234 ng/cm(2), respectively for an absorbance of 0.001. Cadmium(II), copper(II), mercury(II), zinc(II), iodide and sulfide interfere with the cyanide determination. One of the proposed methods was applied to the determination of cyanide in waste-water samples, with satisfactory results.

  2. Formation of radical cations of diaryloxadiazoles

    International Nuclear Information System (INIS)

    Helmstreit, W.

    1988-01-01

    The nature of the formation of the radical cation of the 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole (PC) in liquid n-butyl chloride and acetonitrile has been investigated by observing excited state fluorescence and transient absorption using nanosecond pulse radiolysis and laser flash photolysis. The formation of solute oxonium ions has also been observed. At concentrations -4 mol dm -3 the growth time at which the transient absorption of the radical cation reaches the maximum follows the rise time of the electron pulse ( 2 laser yields the solute radical cation in an acetonitrile solution of 2 x 10 -4 mol dm -3 PC via an electronically excited state. Here, the generation time was smaller than 5 ns. The yield of the cation is increased by addition of CCl 4 . A reaction mechanism is proposed that explains the fast cation formation in terms of an exciplex formed by interaction between an electronically excited state of diaryloxadiazole and the ground state of the solvent. This exciplex yields the solute radical cation. (author)

  3. Luminescent sulfides of monovalent and trivalent cations

    International Nuclear Information System (INIS)

    1975-01-01

    The invention discloses a family of luminescent materials or phosphors having a rhombohedral crystal structure and consisting essentially of a mixed host sulfide of at least one monovalent host cation and at least one trivalent host cation, and containing, for each mole of phosphor, 0.0005 to 0.05 mole of at least one activating cation. The monovalent host cations may be Na, K or Rb and Cs. The trivalent host cations may be Gd, La, Lu, Sc and Y. The activating cations may be one or more of trivalent As, Bi, Ce, Dy, Er, Pr, Sb, Sm, Tb and Tm; divalent Lu, Mn, Pb and Sn; and monovalent Ag, Cu and Tl. The novel phosphors may be used in devices to convert electron-beam, ultraviolet or x-ray energy to light in the visible spectrum. Such energy conversion can be employed for example in fluoroscopic screens, and in viewing screens of cathode-ray tubes and other electron tubes

  4. Chemical analysis of rare earth elements

    International Nuclear Information System (INIS)

    Tsukahara, Ryoichi; Sakoh, Takefumi; Nagai, Iwao

    1994-01-01

    Recently attention has been paid to ICP-AES or ICP-MS, and the reports on the analysis of rare earth elements by utilizing these methods continue to increase. These reports have become to take about 30% of the reports on rare earth analysis, and this is because these methods are highly sensitive to rare earth elements, and also these methods have spread widely. In ICP-AES and ICP-MS, mostly solution samples are measured, therefore, solids must be made into solution. At the time of quantitatively determining the rare earth elements of low concentration, separation and concentration are necessary. Referring to the literatures reported partially in 1990 and from 1991 to 1993, the progress of ICP-AES and ICP-MS is reported. Rare earth oxides and the alloys containing rare earth elements are easily decomposed with acids, but the decomposition of rocks is difficult, and its method is discussed. The separation of the rare earth elements from others in geochemical samples, cation exchange process is frequently utilized. Also solvent extraction process has been studied. For the separation of rare earth elements mutually, chromatography is used. The spectral interference in spectral analysis was studied. The comparison of these methods with other methods is reported. (K.I)

  5. Determination of Acidity and Alkalinity of Food Materials

    OpenAIRE

    三浦,芳助; 福永,祐子; 瀧川,裕里子; 津田,真美; 渡辺,陽子; 瀨山,一正

    2006-01-01

    The acidity and alkalinity of food materials in various menus was determined to clarify the influence of food on physiological functions. Menus mainly containing alkaline food materials (alkaline menu) and acid ones (acid menu) were compared. Determination of acidity and alkalinity was performed for each food material in the alkaline menu and acid menu, and acidity and alkalinity of one meal and a day's one were estimated. 1. Most of food materials in acid menu were assessed to be...

  6. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  7. Zoledronate complexes. III. Two zoledronate complexes with alkaline earth metals: [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)] and [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n).

    Science.gov (United States)

    Freire, Eleonora; Vega, Daniel R; Baggio, Ricardo

    2010-06-01

    Diaquabis[dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato-kappa(2)O,O']magnesium(II), [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)], consists of isolated dimeric units built up around an inversion centre and tightly interconnected by hydrogen bonding. The Mg(II) cation resides at the symmetry centre, surrounded in a rather regular octahedral geometry by two chelating zwitterionic zoledronate(1-) [or dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonate] anions and two water molecules, in a pattern already found in a few reported isologues where the anion is bound to transition metals (Co, Zn and Ni). catena-Poly[[aquacalcium(II)]-mu(3)-[hydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato]-kappa(5)O:O,O':O',O''], [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n), consists instead of a Ca(II) cation in a general position, a zwitterionic zoledronate(2-) anion and a coordinated water molecule. The geometry around the Ca(II) atom, provided by six bisphosphonate O atoms and one water ligand, is that of a pentagonal bipyramid with the Ca(II) atom displaced by 0.19 A out of the equatorial plane. These Ca(II) coordination polyhedra are ;threaded' by the 2(1) axis so that successive polyhedra share edges of their pentagonal basal planes. This results in a strongly coupled rhomboidal Ca(2)-O(2) chain which runs along [010]. These chains are in turn linked by an apical O atom from a -PO(3) group in a neighbouring chain. This O-atom, shared between chains, generates strong covalently bonded planar arrays parallel to (100). Finally, these sheets are linked by hydrogen bonds into a three-dimensional structure. Owing to the extreme affinity of zoledronic acid for bone tissue, in general, and with calcium as one of the major constituents of bone, it is expected that this structure will be useful in modelling some of the biologically interesting processes in which the drug takes part.

  8. The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?

    Directory of Open Access Journals (Sweden)

    Gerry K. Schwalfenberg

    2012-01-01

    Full Text Available This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine.

  9. The Alkaline Diet: Is There Evidence That an Alkaline ph Diet Benefits Health?

    International Nuclear Information System (INIS)

    Schwalfenberg, G.K.

    2012-01-01

    This review looks at the role of an alkaline diet in health. Pub med was searched looking for articles on ph, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine

  10. Alkaline Activator Impact on the Geopolymer Binders

    Science.gov (United States)

    Błaszczyński, Tomasz Z.; Król, Maciej R.

    2017-10-01

    Concrete structures are constantly moving in the direction of improving the durability. Durability depends on many factors, which are the composition of concrete mix, the usage of additives and admixtures and the place, where material will work and carry the load. The introduction of new geopolymer binders for geopolymer structures adds a new aspect that is type of used activator. This substance with strongly alkaline reaction is divided because of the physical state, the alkaline degree and above all the chemical composition. Taking into account, that at present the geopolymer binders are made essentially from waste materials or by-products from the combustion of coal or iron ore smelting, unambiguous determination of the effect of the activator on the properties of the geopolymer material requires a number of trials, researches and observation. This paper shows the influence of the most alkaline activators on the basic parameters of the durability of geopolymer binders. In this study there were used highly alkaline hydroxides, water glasses and granules, which are waste materials in a variety of processes taking place in chemical plants. As the substrate of geopolymer binders there were used fly ash which came from coal and high calcareous ash from the burning of lignite.

  11. ENHANCED OIL RECOVERY USING LOCAL ALKALINE

    African Journals Online (AJOL)

    user

    the discovery of new oil producing fields and the ever increasing ... followed by water flooding is between 35 to 50% of the ... involved and lack of scale up and is considered among ... carbonate alkaline chemical reacts with certain types of ... reservoirs because of the profusion of calcium and the ... damage the formation.

  12. Electrochemical behaviour of alkaline copper complexes

    Indian Academy of Sciences (India)

    Abstract. 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.

  13. Biomass production on saline-alkaline soils

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, A.N.

    1985-01-01

    In a trial of twelve tree species (both nitrogen fixing and non-fixing) for fuel plantations on saline-alkaline soil derived from Gangetic alluvium silty clay, Leucaena leucocephala failed completely after showing rapid growth for six months. Results for other species at age two showed that Prosopis juliflora had the best productivity.

  14. Synthetic, spectroscopic and structural studies on 4-aminobenzoate complexes of divalent alkaline earth metals: x-ray crystal structures of [[Mg(H2O)6] (4-aba)2].2H2O and [Ca(H2O)2(4-aba)2] (4-aba=4-aminobenzoate)

    International Nuclear Information System (INIS)

    Murugavel, Ramaswamy; Karambelkar, Vivek V.; Anantharaman, Ganapathi

    2000-01-01

    Reactions between MCl 2 .nH 2 O (M = Mg, Ca, Sr, and Ba) and 4-aminobenzoic acid (4-abaH) result in the formation of complexes [(Mg(H 2 O) 6 )(4-aba) 2 ) .2H 2 O (I), [Ca(4-aba) 2 (H2 O ) 2 ] (2), [Sr(4-aba) 2 (H2 O ) 2 ] (3), and [Ba(4-aba) 2 Cl] (4), respectively. The new compounds 1 and 2, as well as the previously reported 3 and 4 form an extended intra- and intermolecular hydrogen bonded network in the solid-state. The compounds have been characterized by elemental analysis, pH measurements, thermogravimetric studies, and IR, NMR, and UV-Vis spectroscopy. The solid state structures of the molecules 1 and 2 have been determined by single crystal x-ray diffraction studies. In the case of magnesium complex 1, the dipositively charged Mg cation is surrounded by six water molecules and the two 4-aminobenzoate ligands show no direct bonding to the metal ion. The calcium ion in 2 is octa-coordinated with direct coordination of the 4-aminobenzoate ligands to the metal ion. The Ca-Ca separation in the polymeric chain of 2 is 3.9047(5) A. (author)

  15. Accelerators for forming cationic technetium complexes useful as radiodiagnostic images

    International Nuclear Information System (INIS)

    Tweedle, M.F.

    1985-01-01

    This invention relates to compositions for making cationic radiodiagnostic agents and, in particular, to accelerator compounds for labelling such cationic radiodiagnostic agents, kits for preparing such 99m Tc-labelled cationic radiodiagnostic agents with technetium, and methods for labelling such cationic radiodiagnostic agents with technetium

  16. Hexagonal perovskites with cationic vacancies. 32. Photoluminescence of trivalent rare earth in the systems Ba/sub 2-y/Sr/sub y/La/sub 2-x/RE/sub x/MgW/sub 2/vacantO/sub 12/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1982-06-01

    In the series Ba/sub 2-y/Sr/sub y/La/sub 2-x/RE/sub x/MgW/sub 2/vacantO/sub 12/ the Ba/sup 2 +/ can be completely substituted by Sr/sup 2 +/. All compounds crystallize in the rhombohedral 12 L-type (space group R-3m; sequence (hhcc)/sub 3/). By doping the stacking polytypes with some of the trivalent rare earths efficient visible photoluminescence is obtained. The simultaneous incorporation of two different rare earth ions leads to two-color-phosphors, which, according to the excitation energy used, emit either mainly the typical spectrum from one or the other activator; the corresponding luminescence mechanism are discussed.

  17. Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

    Science.gov (United States)

    Lenton, Andrew; Matear, Richard J.; Keller, David P.; Scott, Vivian; Vaughan, Naomi E.

    2018-04-01

    Atmospheric carbon dioxide (CO2) levels continue to rise, increasing the risk of severe impacts on the Earth system, and on the ecosystem services that it provides. Artificial ocean alkalinization (AOA) is capable of reducing atmospheric CO2 concentrations and surface warming and addressing ocean acidification. Here, we simulate global and regional responses to alkalinity (ALK) addition (0.25 PmolALK yr-1) over the period 2020-2100 using the CSIRO-Mk3L-COAL Earth System Model, under high (Representative Concentration Pathway 8.5; RCP8.5) and low (RCP2.6) emissions. While regionally there are large changes in alkalinity associated with locations of AOA, globally we see only a very weak dependence on where and when AOA is applied. On a global scale, while we see that under RCP2.6 the carbon uptake associated with AOA is only ˜ 60 % of the total, under RCP8.5 the relative changes in temperature are larger, as are the changes in pH (140 %) and aragonite saturation state (170 %). The simulations reveal AOA is more effective under lower emissions, therefore the higher the emissions the more AOA is required to achieve the same reduction in global warming and ocean acidification. Finally, our simulated AOA for 2020-2100 in the RCP2.6 scenario is capable of offsetting warming and ameliorating ocean acidification increases at the global scale, but with highly variable regional responses.

  18. Selective crystallization of cations with crown ethers; Selektive Kristallisation von Kationen mit Kronenethern

    Energy Technology Data Exchange (ETDEWEB)

    Heffels, Dennis Egidius

    2014-07-04

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  19. Production of alkaline proteases by alkalophilic Bacillus subtilis ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    2016-11-23

    Nov 23, 2016 ... Key words: Production, alkaline protease, Bacillus subtilis, animal wastes, enzyme activity. ... Generally, alkaline proteases are produced using submerged fermentation .... biopolymer concentrations were reported to have an influence ... adding nitrogenous compounds stimulate microorganism growth and ...

  20. Osteocalcin and bone-specific alkaline phosphatase in Sickle cell ...

    African Journals Online (AJOL)

    specific alkaline phosphatase (b-AP) total protein levels were evaluated as indicators of bone turnover in twenty patients with sickle cell haemoglobinopathies and in twenty normal healthy individuals. The serum bonespecific alkaline phosphatase ...