WorldWideScience

Sample records for alkali metal cations

  1. The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

    OpenAIRE

    Previdello, B.; E. Machado; Varela, H.

    2014-01-01

    Non-covalent interactions between hydrated alkali metal cations and adsorbed oxygenated species on platinum might considerably inhibit some electrocatalytic reactions. We report in this communication the effect exerted by electrolyte alkali metal cations on the electro-oxidation of formate ions on platinum. The system was investigated by means of cyclic voltammetry and chronoamperometry in the presence of an electrolyte containing Li+, Na+, or K+. As already observed for other systems, the ge...

  2. Properties of solvated electrons, alkali anions and other species in metal solutions and kinetics of cation and electron exchange reactions. Final report

    International Nuclear Information System (INIS)

    The properties of solutions of alkali metals in amine solvents were studied by optical, ETR, NMR and electrochemical methods. Complexation of the alkali cations by crown ethers and cryptands permitted the preparation of concentrated solutions of alkali metals in amine and ether solvents. Extensive alkali metal NMR studies of the exchange of M+ with crown-ethers and cryptands and of the alkali metal anion, M-, were made. The first crystalline salt of an alkali metal anion, Na+ Cryptand [2.2.2]Na- was synthesized and characterized and led to the preparation of other alkali metal anion salts. This research provided the foundation for continuing studies of crystalline alkalide salts

  3. The role of alkali metal cations in the stabilization of guanine quadruplexes: why K(+) is the best.

    Science.gov (United States)

    Zaccaria, F; Paragi, G; Fonseca Guerra, C

    2016-08-21

    The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li(+), Na(+), K(+), Rb(+), and Cs(+). The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity. PMID:27185388

  4. Potential-modulated intercalation of alkali cations into metal hexacyanoferrate coated electrodes. 1998 annual progress report

    International Nuclear Information System (INIS)

    'This program is studying potential-driven cation intercalation and deintercalation in metal hexacyanoferrate compounds, with the eventual goal of creating materials with high selectivity for cesium separations and long cycle lifetimes. The separation of radiocesium from other benign cations has important implications for the cost of processing a variety of cesium contaminated DOE wasteforms. This report summarizes results after nine months of work. Much of the initial efforts have been directed towards quantitatively characterizing the selectivity of nickel hexacyanoferrate derivatized electrodes for intercalating cesium preferentially over other alkali metal cations. Using energy dispersive xray spectroscopy (ex-situ, but non-destructive) and ICP analysis (ex-situ and destructive), the authors have demonstrated that the nickel hexacyanoferrate lattice has a strong preference for intercalated cesium over sodium. For example, when ions are reversibly loaded into a nickel hexacyanoferrate thin film from a solution containing 0.9999 M Na+ and 0.0001 M Cs+, the film intercalates 40% as much Cs+ as when loaded from pure 1 M Cs+ containing electrolyte (all electrolytes use nitrates as the common anion). The authors have also shown that, contrary to the common assumptions found in the literature, a significant fraction of the thin film is not active initially. A new near infrared laser has been purchased and is being added to the Raman spectroscopy facilities to allow in-situ studies of the intercalation processes.'

  5. Potential Modulated Intercalation of Alkali Cations into Metal Hexacyanoferrate Coated Electrodes

    International Nuclear Information System (INIS)

    Nickel hexacyanoferrate is a polynuclear inorganic ion intercalation material that loads (intercalates) and elutes (deintercalates) alkali cations from its structure when electrochemically reduced and oxidized, respectively. Nickel hexacyanoferrrate (NiHCF) is known to preferentially intercalate cesium over all other alkali cations, thus providing a basis for a separation scheme that can tackle DOE's radiocesium contamination problem. This program studied fundamental issues in alkalization intercalation and deintercalation in nickel hexacyanoferrate compounds, with the goal of (1) quantifying the ion exchange selectivity properties from cation mixtures, (2) enhancing ion exchange capacities, and (3) and understanding the electrochemically-switched ion exchange process (ESIX)

  6. Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

    Institute of Scientific and Technical Information of China (English)

    Yan Cao; Yunxia Zhao; Fujiao Song; Qin Zhong

    2014-01-01

    Metal-organic frameworks (MOFs) have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-1(also named Cu-BTC or MOF-199) was chemically reduced by doping it with alkali metals (Li, Na and K) and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction (XRD), thermo-gravimetric analysis (TGA) and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li+, Na+ and K+, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11%increase in adsorption capacity at 298 K and 18 bar as compared with HKUST-1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.

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

    Science.gov (United States)

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

    2016-06-01

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

  8. Nano-baskets of Calix[4]-1,3-crown in Emulsion Membranes for Selective Extraction of Alkali Metal Cations

    Institute of Scientific and Technical Information of China (English)

    Bahram Mokhtari; Kobra Pourabdollah

    2013-01-01

    Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclu-sion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of diacid calix[4]-1,3-crowns-4,5 were synthesized, and their inclusion-extraction parameters were optimized including the calixcrown scaffold (4.4%, by mass) as the carrier/demulsifier, the commercial kero-sene as diluent in membrane, sulphonic acid (0.2 mol·L-1) and ammonium carbonate (0.4 mol·L-1) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 r·min-1), and initial solute concen-tration (100 mg·L-1). The selectivity of membrane over more than ten interfering cations was examined and the re-sults reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98%-99%.

  9. Alkali metal cation complexation and solvent interactions by robust chromium(III) fluoride complexes

    DEFF Research Database (Denmark)

    Birk, T.; Magnussen, M.J.; Piligkos, Stergios;

    2010-01-01

    Interaction of robust chromium(III) fluoride complexes with sodium or lithium cations in solution lead to hypsochromic spectral shifts of increasing magnitude along the series: trans-[CrF2(py)(4)](+), mer-[CrF3(terpy)], and fac-[CrF3(Me(3)tacn)]. Crystalline products isolated from solution exhibit......)] have been synthesized from mer-[CrF3(py)(3)] and shown to precipitate sodium salts from solution, of which 3[CrF3(Me(3-)tacn)]center dot 2Na(Bph(4)).solv and 6[CrF3(terpy)]center dot 4Na(Bph(4)).solv have been crystallographically characterized. In these clusters, the neutral fluoride complexes bring...

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

    Science.gov (United States)

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

    2015-07-01

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

  11. Alkali metal ionization detector

    Science.gov (United States)

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  12. Three Alkali-Metal-Gold-Gallium Systems. Ternary Tunnel Structures and Some Problems with Poorly Ordered Cations

    Energy Technology Data Exchange (ETDEWEB)

    Smetana, Volodymyr; Miller, Gordon J.; Corbett, John D.

    2012-06-27

    Six new intermetallic compounds have been characterized in the alkali metal (A = Na, Rb, Cs)–gold–gallium systems. Three isostructural compounds with the general composition A0.55Au2Ga2, two others of AAu3Ga2 (A = Rb, Cs), and the related Na13Au41.2Ga30.3 were synthesized via typical high-temperature reactions and their crystal structures determined by single-crystal X-ray diffraction analysis: Na0.56(9)Au2Ga2 (I, I4/mcm, a = 8.718(1) Å, c = 4.857(1) Å, Z = 4), Rb0.56(1)Au2Ga2 (II, I4/mcm, a = 8.950(1) Å, c = 4.829(1) Å, Z = 4), Cs0.54(2)Au2Ga2 (III, I4/mcm, a = 9.077(1) Å, c = 4.815(1) Å, Z = 4), RbAu3Ga2 (IV, Pnma, a = 13.384(3) Å, b = 5.577(1) Å, c = 7.017(1) Å, Z = 4), CsAu3Ga2 (V, Pnma, a = 13.511(3) Å, b = 5.614(2) Å, c = 7.146(1) Å, Z = 4), Na13Au41.2(1)Ga30.3(1) (VI, P6 mmm, a = 19.550(3) Å, c = 8.990(2) Å, Z = 2). The first three compounds (I–III) are isostructural with tetragonal K0.55Au2Ga2 and likewise contain planar eight-member Au/Ga rings that stack along c to generate tunnels and that contain varying degrees of disordered Na–Cs cations. The cation dispositions are much more clearly and reasonably defined by electron density mapping than through least-squares refinements with conventional anisotropic ellipsoids. Orthorhombic AAu3Ga2 (IV, V) are ordered ternary Rb and Cs derivatives of the SrZn5 type structure, demonstrating structural variability within the AAu3Ga2 family. All attempts to prepare an isotypic “NaAu3Ga2” were not successful, but yielded only a similar composition Na13Au41.2Ga30.3 (NaAu3.17Ga2.33) (VI) in a very different structure with two types of cation sites. Crystal orbital Hamilton population (COHP) analysis obtained from tight-binding electronic structure calculations for idealized I–IV via linear muffin-tin-orbital (LMTO) methods emphasized the major contributions of heteroatomic Au–Ga bonding to the structural stability of these compounds. The relative minima (pseudogaps) in the DOS curves for IV

  13. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites. PMID:20937860

  14. Methods of recovering alkali metals

    Science.gov (United States)

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  15. Hydrothermal alkali metal recovery process

    Science.gov (United States)

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  16. Upgrading platform using alkali metals

    Science.gov (United States)

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  17. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

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

  18. Phosphorus-containing podands. 9. Synthesis of oligoethylene glycol bis(diphenylphospinylethyl) esters and their complexing properties with respect to alkali metal cations in a low-polarity solvent

    International Nuclear Information System (INIS)

    The complexing ability of phosphoryl-containing monopodands with the general formula Ph2P(O)CH2CH2O(CH2CH2O)nCH2CH2P(O)Ph2 (n = 0-5, 6.4, 8.7, 13.2) with respect to alkali metal cations was investigated conductometrically in tetrahydrofuran:chloroform mixed solvent (4:1, vol.) at 25 degrees C. It was found that ligands of this type are efficient complexing agents relative to all alkali metal cations, and the monopodand with n = 0 also exhibits elevated Li/Na and Li/K selectivity. The effect of the structure, particularly the rigidity of the terminal fragments of the monopodands, on their complexing capacity was discussed. The method of synthesis of this type of ligand was described. 12 refs., 1 fig., 3 tabs

  19. Corrosion by the Alkali Metals

    International Nuclear Information System (INIS)

    This is a review of the state of the art of corrosion testing of materials by the alkali metals, the models proposed to explain the observed corrosion results, and the status of materials selection for application in alkali metal-cooled systems. Corrosion of structural and fuel cladding materials by liquid Na and NaK has been studied intensively, but intermittently for the last 18 years. These studies and the liquid-metal-cooled reactors in operation demonstrate that stainless steels can be considered for structural and cladding applications below 650°C. Above this temperature increased corrosion and radiation-induced embrittlement make them unsatisfactory. Corrosion models are reviewed and their inability to explain all the experimental observations discussed. An alternate model is proposed which qualitatively is in agreement with experimental observations. In this model, the rate-controlling step is either the surface reaction of Fe with ''available oxygen'' (dissolved Na2O) to form an Fe-O-Na complex or the rate at which ''available oxygen'' can reach the surface to form the complex; which process is rate controlling depends on the temperature, Na velocity and oxygen concentration in the Na. The solution chemistry of oxygen, carbon and alkali metal-oxygen-transition metal complexes dissolved in the alkali metals is reviewed. ''Molecular'' complexes appear unlikely to exist in solution in the alkali metals, although the thermodynamic tendencies for them to form suggest that stable bonds exist in solution between oxygen, the transition and the alkali metals. The insolubility of carbon in ''oxygen-free'' sodium indicates that carbon transfer may be associated with oxygen in sodium down to very low oxygen levels, although experimental data do not generally confirm this postulate. Corrosion of refractory metals by boiling alkali metals at temperatures above 1000°C is markedly affected by impurities in either the liquid or refractory metal; the addition of Ti, Zr or

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

    International Nuclear Information System (INIS)

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

  1. Alkali and transition metal phospholides

    International Nuclear Information System (INIS)

    Major tendencies in modern chemistry of alkali and transition metal phospholides (phosphacyclopentadienides) are systematized, analyzed and generalized. Basic methods of synthesis of these compounds are presented. Their chemical properties are considered with a special focus on their complexing ability. Potential applications of phospholides and their derivatives are discussed. The bibliography includes 184 references

  2. Alkali metal sources for OLED devices

    Science.gov (United States)

    Cattaneo, Lorena; Longoni, Giorgio; Bonucci, Antonio; Tominetti, Stefano

    2005-07-01

    In OLED organic layers electron injection is improved by using alkali metals as cathodes, to lower work function or, as dopants of organic layer at cathode interface. The creation of an alkali metal layer can be accomplished through conventional physical vapor deposition from a heated dispenser. However alkali metals are very reactive and must be handled in inert atmosphere all through the entire process. If a contamination takes place, it reduces the lithium deposition rate and also the lithium total yield in a not controlled way. An innovative alkali metal dispensing technology has been developed to overcome these problems and ensure OLED alkali metal cathode reliability. The alkali Metal dispenser, called Alkamax, will be able to release up to a few grams of alkali metals (in particular Li and Cs) throughout the adoption of a very stable form of the alkali metal. Lithium, for example, can be evaporated "on demand": the evaporation could be stopped and re-activated without losing alkali metal yield because the metal not yet consumed remains in its stable form. A full characterization of dispensing material, dispenser configuration and dispensing process has been carried out in order to optimize the evaporation and deposition dynamics of alkali metals layers. The study has been performed applying also inside developed simulations tools.

  3. Structure, spectra and dynamics of alkali cation microhydration clusters

    OpenAIRE

    Schulz, Franziska

    2005-01-01

    The main focus of this work was the theoretical investigation of alkali cation microhydration clusters with sodium, potassium, and caesium as central ion and up to 24 water molecules per cluster. Structures were obtained applying global geometry optimisation, using a specialised version of genetic algorithms and the common TIP4P/OPLS model potential. The global and most important local minimum energy structures have been investigated and the results obtained constitute a first complete and sy...

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

    Directory of Open Access Journals (Sweden)

    Uma Sharma

    2006-08-01

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

  5. Influence of the alkali metal cation on the fragmentation of monensin in ESI-MS/MS Influência de cátions de metais alcalinos sobre a fragmentação de monensina em ESI-MS/MS

    OpenAIRE

    Norberto Peporine Lopes; Filipe Alexandre Almeida-Paz; Paul Jonathan Gates

    2006-01-01

    The MS/MS fragmentation of the alkali metal complexes of monensin A are studied. The increase in alkali metal ionic radii decreases the ability of the Grob-Wharton fragmentation mechanism to occur and reduces the overall degree of fragmentation. Conversely, the electronegativity of the metal cation is related to the number of fragment ions observed.O presente trabalho relata os estudos de fragmentação por espectrometria de massas seqüencial de complexos formados pela monensina A e uma série d...

  6. High and rapid alkali cation storage in ultramicroporous carbonaceous materials

    Science.gov (United States)

    Yun, Young Soo; Lee, Seulbee; Kim, Na Rae; Kang, Minjee; Leal, Cecilia; Park, Kyu-Young; Kang, Kisuk; Jin, Hyoung-Joon

    2016-05-01

    To achieve better supercapacitor performance, efforts have focused on increasing the specific surface area of electrode materials to obtain higher energy and power density. The control of pores in these materials is one of the most effective ways to increase the surface area. However, when the size of pores decreases to a sub-nanometer regime, it becomes difficult to apply the conventional parallel-plate capacitor model because the charge separation distance (d-value) of the electrical double layer has a similar length scale. In this study, ultramicroporous carbonaceous materials (UCMs) containing sub-nanometer-scale pores are fabricated using a simple in situ carbonization/activation of cellulose-based compounds containing potassium. The results show that alkali cations act as charge carriers in the ultramicropores (<0.7 nm), and these materials can deliver high capacitances of ∼300 F g-1 at 0.5 A g-1 and 130 F g-1, even at a high current rate of 65 A g-1 in an aqueous medium. In addition, the UCM-based symmetric supercapacitors are stable over 10,000 cycles and have a high energy and power densities of 8.4 Wh kg-1 and 15,000 W kg-1, respectively. This study provides a better understanding of the effects of ultramicropores in alkali cation storage.

  7. Sorption selectivity of alkali metal ions in polymer inclusion ion exchange membranes

    International Nuclear Information System (INIS)

    Sorption selectivity of different alkali metal ions in polymer inclusion cation exchange membranes has been studied. The concentration of the metal ions were measured using neutron activation analysis. The results show the selectivity of polymer inclusion membranes for metal ions in the order Na++++. The trend have been explained in terms of the radius of the hydrated metal ion. (author)

  8. Alkali-metal intercalation in carbon nanotubes

    Science.gov (United States)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  9. Alkali Metal Variation and Twisting of the FeNNFe Core in Bridging Diiron Dinitrogen Complexes.

    Science.gov (United States)

    McWilliams, Sean F; Rodgers, Kenton R; Lukat-Rodgers, Gudrun; Mercado, Brandon Q; Grubel, Katarzyna; Holland, Patrick L

    2016-03-21

    Alkali metal cations can interact with Fe-N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber-Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding their influence on transition metal-dinitrogen complexes. In this work, we varied the alkali metal in [alkali cation]2[LFeNNFeL] complexes (L = bulky β-diketiminate ligand) through the size range from Na(+) to K(+), Rb(+), and Cs(+). The FeNNFe cores have similar Fe-N and N-N distances and N-N stretching frequencies despite the drastic change in alkali metal cation size. The two diketiminates twist relative to one another, with larger dihedral angles accommodating the larger cations. In order to explain why the twisting has so little influence on the core, we performed density functional theory calculations on a simplified LFeNNFeL model, which show that the two metals surprisingly do not compete for back-bonding to the same π* orbital of N2, even when the ligand planes are parallel. This diiron system can tolerate distortion of the ligand planes through compensating orbital energy changes, and thus, a range of ligand orientations can give very similar energies. PMID:26925968

  10. The heats of adsorption of metal cations on silica gel with covalently fixed polyaspartic acid

    International Nuclear Information System (INIS)

    Temperature dependence of retaining cations of alkali (Li-Cs), alkaline-earth (Mg, Ca, Sr, Ba) metals and cadmium on silica gel with covalently fixed polyaspartic acid, as well as on carboxylic cation exchangers Universal Cation and Selekton K, was studied by the method of chromatography in the temperature range of 27-62 deg C. On the basis of the experimental data obtained adsorption heat of alkali and alkaline-earth metal cations was calculated. It was ascertained that for all the sorbents studied ion exchange prevails in retaining mechanism. Three types of cation retaining dependence on chromatographic column temperature were considered

  11. Influence of the alkali metal cation on the fragmentation of monensin in ESI-MS/MS Influência de cátions de metais alcalinos sobre a fragmentação de monensina em ESI-MS/MS

    Directory of Open Access Journals (Sweden)

    Norberto Peporine Lopes

    2006-09-01

    Full Text Available The MS/MS fragmentation of the alkali metal complexes of monensin A are studied. The increase in alkali metal ionic radii decreases the ability of the Grob-Wharton fragmentation mechanism to occur and reduces the overall degree of fragmentation. Conversely, the electronegativity of the metal cation is related to the number of fragment ions observed.O presente trabalho relata os estudos de fragmentação por espectrometria de massas seqüencial de complexos formados pela monensina A e uma série de metais alcalinos. Foi observado que o aumento do raio iônico do metal alcalino levou a uma diminuição do mecanismo de fragmentação do tipo Grob-Wharton e ao grau de fragmentação. Por outro lado, a maior eletronegatividade mostrou estar relacionada ao número de fragmentos observados.

  12. Recovery of alkali metal constituents from catalytic coal conversion residues

    Science.gov (United States)

    Soung, W.Y.

    In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide to precipitate silicon constituents, the pH of the resultant solution is increased, preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  13. Alkali metals in fungi of forest soil

    International Nuclear Information System (INIS)

    The high affinity of forest soil fungi for alkali metals such as potassium, rubidium, caesium as well as radiocaesium is shown and discussed. Good positive correlation was found between K: Rb concentration ratios in soil and in fungi, when correlation between K: Cs concentration ratios was less pronounced. (LN)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

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

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

    International Nuclear Information System (INIS)

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

  17. Developments in alkali-metal atomic magnetometry

    Science.gov (United States)

    Seltzer, Scott Jeffrey

    Alkali-metal magnetometers use the coherent precession of polarized atomic spins to detect and measure magnetic fields. Recent advances have enabled magnetometers to become competitive with SQUIDs as the most sensitive magnetic field detectors, and they now find use in a variety of areas ranging from medicine and NMR to explosives detection and fundamental physics research. In this thesis we discuss several developments in alkali-metal atomic magnetometry for both practical and fundamental applications. We present a new method of polarizing the alkali atoms by modulating the optical pumping rate at both the linear and quadratic Zeeman resonance frequencies. We demonstrate experimentally that this method enhances the sensitivity of a potassium magnetometer operating in the Earth's field by a factor of 4, and we calculate that it can reduce the orientation-dependent heading error to less than 0.1 nT. We discuss a radio-frequency magnetometer for detection of oscillating magnetic fields with sensitivity better than 0.2 fT/ Hz , which we apply to the observation of nuclear magnetic resonance (NMR) signals from polarized water, as well as nuclear quadrupole resonance (NQR) signals from ammonium nitrate. We demonstrate that a spin-exchange relaxation-free (SERF) magnetometer can measure all three vector components of the magnetic field in an unshielded environment with comparable sensitivity to other devices. We find that octadecyltrichlorosilane (OTS) acts as an anti-relaxation coating for alkali atoms at temperatures below 170°C, allowing them to collide with a glass surface up to 2,000 times before depolarizing, and we present the first demonstration of high-temperature magnetometry with a coated cell. We also describe a reusable alkali vapor cell intended for the study of interactions between alkali atoms and surface coatings. Finally, we explore the use of a cesium-xenon SERF comagnetometer for a proposed measurement of the permanent electric dipole moments (EDMs

  18. Alkali metal ion binding to glutamine and glutamine derivatives investigated by infrared action spectroscopy and theory

    NARCIS (Netherlands)

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

    2008-01-01

    The gas-phase structures of alkali-metal cationized glutamine are investigated by using both infrared multiple photon dissociation (TRMPD) action spectroscopy, utilizing light generated by a free electron laser, and theory. The IRMPD spectra contain many similarities that are most consistent with gl

  19. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    The coprecipitation of alkali metal ions Li+, Na+, K+ and Rb+ with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na+ which has approximately the same ionic radius as Ca2+. (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li+, Na+, K+ and Rb+) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li+, K+ and Rb+) into the aragonite. (author)

  20. Cathode architectures for alkali metal / oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  1. Superconductivity in alkali metal intercalated iron selenides.

    Science.gov (United States)

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  2. Superconductivity in alkali metal intercalated iron selenides

    Science.gov (United States)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  3. Study on alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting β''-alumina solid electrolyte (BASE) is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies (20-40%), high power densities (1 W/cm2), no moving parts, low maintenance requirements, high durability, and efficiency independent of size. Because of these merits, AMTEC is one of the most promising candidate for dispersed small scale power station, remote power station and aerospace power systems. In this paper, the theoretical and experimental studies on the thin film electrodes characteristics, power generating characteristics, cell efficiency, integral electrode with large current lead, porous metal current lead, series connected cells power generation, potassium AMTEC, wick return AMTEC and system analysis for space and grand use are reported. (J.P.N.) 79 refs

  4. Hydration number of alkali metal ions determined by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2008-01-01

    In aqueous solutions, the alkali metals ions are associated with a number of H2O molecules. A distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and a secondary (or outer) solvation shell, consisting of...... all other water molecules whose properties are still influenced significantly by the cation. Knowing the hydration number is important when considering, for instance, the transport of Na+ and K+ in biological cell membranes, since their different behavior may depend on the details of ion hydration....... The solvation of alkali metal ions has been discussed for many years without a clear consensus. This work presents a systematic study of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile...

  5. Saturated vapor pressure over molten mixtures of GaCl3 and alkali metal chlorides

    International Nuclear Information System (INIS)

    Volatilities of GaCl3 and alkali metal chlorides over diluted (up to 3 mol %) solutions of GaCl3 in LiCl, NaCl, KCl, RbCl, and CsCl were measured at 1100 K by dynamic and indirect static methods. Chemical composition of saturated vapor over the mixed melts was determined. Partial pressures of the components were calculated. Their values depend essentially on specific alkali metal cation and on concentration of GaCl3; their variation permits altering parameters of GaCl3 distillation from the salt melt in a wide range

  6. High-Order Dispersion Coefficients for Alkali-metal Atoms

    Institute of Scientific and Technical Information of China (English)

    KANG Shuai; DING Chi-Kun; CHEN Chang-Yong; WU Xue-Qing

    2013-01-01

    High-order dispersion coefficients C9,C11,C12,and C13 for the ground-state alkali-metals were calculated by combining the l-dependent model potential of alkali-metal atoms and linear variation method based on B-spline basis functions.The results were compared.

  7. The structure of metallic complexes of polyacetylene with alkali metals

    Science.gov (United States)

    Baughman, R. H.; Murthy, N. S.; Miller, G. G.

    1983-07-01

    The crystal structures of sodium, potassium, rubidium, and cesium doped polyacetylene have been determined using crystal packing and x-ray diffraction analyses. Each of these metallic complexes is tetragonal, with the polyacetylene chains forming a host lattice in which the alkali metal ions are present in channels. Lithium appears to be too small to stabilize the channel structure and an amorphous structure is observed. Predicted unit cell parameters and x-ray diffraction intensities are in agreement with observed values. Similarities with the alkali metal doped graphite suggest that hybridization between carbon pz orbitals and metal s orbitals occurs. Such hybridization is expected to result in a high conductivity component normal to the chain direction. On the other hand, direct overlap between polymer chains appears small, since alkali metal columns separate polymer chains. Compositions calculated for the channel structures (from meridional diffraction spacings, the intensity of equatorial diffraction lines, measured volume expansion, and distances in model complexes) all range from y=0.12 to 0.18 for (CHMy)x, where M is sodium, potassium, rubidium, or cesium.

  8. 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 +}.

  9. Solvation structure and transport properties of alkali cations in dimethyl sulfoxide under exogenous static electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Vijayakumar, M., E-mail: Vijay@pnnl.gov, E-mail: karl.mueller@pnnl.gov [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Joint Center for Energy Storage Research, Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Han, Kee Sung [Joint Center for Energy Storage Research, Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Mueller, Karl T., E-mail: Vijay@pnnl.gov, E-mail: karl.mueller@pnnl.gov [Joint Center for Energy Storage Research, Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-06-14

    A combination of molecular dynamics simulations and pulsed field gradient nuclear magnetic resonance spectroscopy is used to investigate the role of exogenous electric fields on the solvation structure and dynamics of alkali ions in dimethyl sulfoxide (DMSO) and as a function of temperature. Good agreement was obtained, for select alkali ions in the absence of an electric field, between calculated and experimentally determined diffusion coefficients normalized to that of pure DMSO. Our results indicate that temperatures of up to 400 K and external electric fields of up to 1 V nm{sup −1} have minimal effects on the solvation structure of the smaller alkali cations (Li{sup +} and Na{sup +}) due to their relatively strong ion-solvent interactions, whereas the solvation structures of the larger alkali cations (K{sup +}, Rb{sup +}, and Cs{sup +}) are significantly affected. In addition, although the DMSO exchange dynamics in the first solvation shell differ markedly for the two groups, the drift velocities and mobilities are not significantly affected by the nature of the alkali ion. Overall, although exogenous electric fields induce a drift displacement, their presence does not significantly affect the random diffusive displacement of the alkali ions in DMSO. System temperature is found to have generally a stronger influence on dynamical properties, such as the DMSO exchange dynamics and the ion mobilities, than the presence of electric fields.

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

    NARCIS (Netherlands)

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

    2006-01-01

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

  11. Diffusion of alkali metals in the first stage graphite intercalation compounds by vdW-DFT calculations

    OpenAIRE

    Wang, Zhaohui; Ratvik, Arne Petter; Grande, Tor; Selbach, Sverre Magnus

    2015-01-01

    Diffusion of alkali metal cations in the first stage graphite intercalation compounds (GIC) LiC6, NaC6, NaC8 and KC8 has been investigated with density functional theory (DFT) calculations using the optPBE-vdW van der Waals functional. The formation energies of alkali vacancies, interstitials and Frenkel defects were calculated and vacancies were found to be the dominating point defects. The diffusion coefficients of the alkali metals in GIC were evaluated by a hopping model of point defects ...

  12. New alkali-metal bidentate borate–malate NaB(DL-C4H4O5)2 and CsB(DL-C4H4O5)2⋅H2O: Effect of cations on the framework structures and macroscopic centricities

    International Nuclear Information System (INIS)

    Graphical abstract: Two novel semiorganic borates NaB(DL-C4H4O5)2 and CsB(DL-C4H4O5)2·H2O display different framework geometries attributable to the size of the alkali-metal cations. NaB(DL-C4H4O5)2 exhibits SHG intensity as high as two times that of KDP. Highlights: • New borate–malate crystals NaB(DL-C4H4O5)2 and CsB(DL-C4H4O5)2⋅H2O have been grown. • They display diverse framework geometries attributable to the size of the cations. • NaB(DL-C4H4O5)2 crystallizes in the noncentrosymmetric monoclinic space group P2. • Both crystals have absorption edges about 220 nm in the UV region. • NaB(DL-C4H4O5)2 exhibits a NLO efficiency of 2 times that of KDP (KH2PO4) standard. -- Abstract: Two new alkali-metal bidenate borate–malate NaB(DL-C4H4O5)2 and CsB(DL-C4H4O5)2⋅H2O have been grown by the facile slow evaporation method through the introduction of acetone as solvent. The crystal structures were determined by single crystal X-ray diffraction. The stoichiometrically equivalent materials crystallize in three-dimensional framework structures and have the same structural unit [B(C4H4O5)2]−. However, both crystals exhibit very diverse framework geometries attributable to the size of the alkali-metal cations, which also leads to the different space groups and macroscopic centricities as proven by SHG test. The noncentrosymmetric NaB(DL-C4H4O5)2 was found to exhibit phase-matchable NLO intensity as high as two times that of KDP standard and a short-wavelength absorption onset at 220 nm. Moreover, both crystals have also been characterized by Infrared spectroscopy and thermogravimetric analysis

  13. The Alkali Metal Interactions with MgO Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtian, Javad [Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi; Bagheri, Zargham [Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of); Kamfiroozi, M. [Islamic Azad University, Shiraz Branch, Shiraz (Iran, Islamic Republic of)

    2012-06-15

    Adsorption of alkali metals (Li, Na, and K) on the surface of magnesium oxide nanotubes (MgONTs) with different diameters was investigated using density functional theory. According to the obtained results, the most stable adsorption site was found to be atop the oxygen atom of the tube surface with adsorption energies in the range of .0.25 to .0.74 eV. HOMO-LUMO gap (E{sub g}) of the tubes dramatically decreases upon the adsorption of the alkali metals, resulting in enhancement of their electrical conductivity enhancement. The order of E{sub g} decrement caused by the metal adsorption is as follows: K > Na > Li. The results suggest that the MgONTs were transformed from semi-insulator to semiconductor upon the alkali metal adsorption. Increasing the tube diameter, the HOMO/LUMO gap of the pristine tube is enhanced and adsorption energies of the alkali metals are decreased

  14. The 4843 Alkali Metal Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    The 4843 AMSF has been used primarily to provide a centralized building to receive and store dangerous and mixed alkali metal waste, including sodium and lithium, which has been generated at the Fast Flux Test Facility and at various other Hanford Site operations that used alkali metals. Most of the dangerous and mixed alkali metal waste received consists of retired equipment from liquid sodium processes. The unit continues to store material. In general, only solid alkali metal waste that is water reactive is stored at the 4843 AMSF. The 4843 AMSF will be closed in a manner consistent with Ecology guidelines and regulations (WAC 173-303-610). The general closure procedure is detailed as follows

  15. Hall Determination of Atomic Radii of Alkali Metals

    Science.gov (United States)

    Houari, Ahmed

    2008-01-01

    I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)

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

    International Nuclear Information System (INIS)

    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-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) 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)

  17. Fundamental study on alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting β''-alumina is a device to convert heat energy to electric energy directly. In this paper, the results of theoretical and experimental studies on AMTEC power generating characteristics, internal electrical resistances of single cell, and system analysis of AMTEC power generating systems are reported. This paper consists of 5 chapters, which are summarized as follows: In chapter 1, a theoretical explanation of AMTEC, a brief survey of the research and development history of AMTEC and a purpose of this paper are reported. In chapter 2, the properties of β''-alumina, preparations of thin film electrodes, and special attention points to be paid in handling of β''-alumina and film electrodes are reported. The AMTEC power generating characteristics of the tubular cells are also reported. In chapter 3, the experimental results of the disk type cells and the theoretical considerations about internal resistances are reported. The causes of electrode erosion are also reported. In chapter 4, the system analysis on AMTEC steam-turbine combined cycle for a dispersed power station and AMTEC power system for a aerospace power are reported. Chapter 5 summarizes major results achieved in the preceding four chapters as a concluding remark. (J.P.N.) 62 refs

  18. Bioinorganic Chemistry of the Alkali Metal Ions.

    Science.gov (United States)

    Kim, Youngsam; Nguyen, Thuy-Tien T; Churchill, David G

    2016-01-01

    The common Group 1 alkali metals are indeed ubiquitous on earth, in the oceans and in biological systems. In this introductory chapter, concepts involving aqueous chemistry and aspects of general coordination chemistry and oxygen atom donor chemistry are introduced. Also, there are nuclear isotopes of importance. A general discussion of Group 1 begins from the prevalence of the ions, and from a comparison of their ionic radii and ionization energies. While oxygen and water molecule binding have the most relevance to biology and in forming a detailed understanding between the elements, there is a wide range of basic chemistry that is potentially important, especially with respect to biological chelation and synthetic multi-dentate ligand design. The elements are widely distributed in life forms, in the terrestrial environment and in the oceans. The details about the workings in animal, as well as plant life are presented in this volume. Important biometallic aspects of human health and medicine are introduced as well. Seeing as the elements are widely present in biology, various particular endogenous molecules and enzymatic systems can be studied. Sodium and potassium are by far the most important and central elements for consideration. Aspects of lithium, rubidium, cesium and francium chemistry are also included; they help in making important comparisons related to the coordination chemistry of Na(+) and K(+). Physical methods are also introduced. PMID:26860297

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

    International Nuclear Information System (INIS)

    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

  20. Phonon Dispersion Relations in Alkali Metals

    International Nuclear Information System (INIS)

    It has been shown in this paper that the phonon dispersion curves of sodium in the [100], [110] and [111] symmetry directions can be explained well on the basis of a simple model, where one has to consider only central force constants between nearest and next nearest neighbours. The tangential force constant between the nearest neighbours is very much smaller as compared to the radial force constant, while for the next nearest neighbours the radial and tangential force constants are comparable. The calculation is carried out on the basis of the model suggested by de Launay, where it is shown that the conduction electrons exert a volume force for longitudinal modes. The stiffness constant of the electron gas is its bulk modulus which in de Launay's model is equal to the Cauchy discrepancy (C12-C14) for the cubic crystals. The three force constants α1, α2 and α1' can be determined from the measured elastic constants and the secular equation can be solved to give the dispersion curves. The dispersion curves have also been obtained using the calculated values of the bulk modulus of the electron gas after considering not only the exchange and correlation energies but also the Fermi kinetic energy. These also agree fairly well with experiment. The measured elastic constants as well as calculated bulk modulus of the electron gas indicate that the Cauchy relation C12 = C44 holds good approximately in alkali metals. This result is rather surprising as it requires that the interaction between the atoms be central in nature in spite of the metallic binding. A justification for this has been given by Cochran. A model with four force constants is being worked out. They can be determined from the three elastic constants and calculated bulk modulus of the electron gas. (author)

  1. A study on optical properties of poly (ethylene oxide) based polymer electrolyte with different alkali metal iodides

    Science.gov (United States)

    Rao, B. Narasimha; Suvarna, R. Padma

    2016-05-01

    Polymer electrolytes were prepared by adding poly (ethylene glycol) dimethyl ether (PEGDME), TiO2 (nano filler), different alkali metal iodide salts RI (R+=Li+, Na+, K+, Rb+, Cs+) and I2 into Acetonitrile gelated with Poly (ethylene oxide) (PEO). Optical properties of poly (ethylene oxide) based polymer electrolytes were studied by FTIR, UV-Vis spectroscopic techniques. FTIR spectrum reveals that the alkali metal cations were coordinated to ether oxygen of PEO. The optical absorption studies were made in the wavelength range 200-800 nm. It is observed that the optical absorption increases with increase in the radius of alkali metal cation. The optical band gap for allowed direct transitions was evaluated using Urbach-edges method. The optical properties such as optical band gap, refractive index and extinction coefficient were determined. The studied polymer materials are useful for solar cells, super capacitors, fuel cells, gas sensors etc.

  2. On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

    International Nuclear Information System (INIS)

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN6), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460–490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches. (paper)

  3. Determination of membrane hydration numbers of alkali metal ions by insertion in a conducting polymer

    DEFF Research Database (Denmark)

    Skaarup, Steen; Junaid Mohamed Jafeen, Mohamed; Careem, M.A.

    2010-01-01

    In aqueous solutions, the alkali metals ions, Li+, Na+, K+, Rb+ and Cs+ are known to be associated with a number of H2O molecules. Traditionally, a distinction is made between a primary solvent shell, (or inner solvation shell), consisting of H2O molecules directly coordinated to the metal ion, and...... a secondary (or outer) solvation shell, consisting of all other water molecules whose properties are still influenced significantly by the cation. Knowing the hydration number is important when considering, for instance, the transport of Na+ and K+ in biological cell membranes, since their different...... necessarily define the same hydration shell. This work presents a systematic study of one special variant of the hydration numbers of the 5 alkali metal ions, using the electrochemical insertion of the ions in a conducting polymer (polypyrrole containing the large immobile anion DBS-). The technique of...

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

    International Nuclear Information System (INIS)

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

  5. [Oat growth and cation absorption characteristics under salt and alkali stress].

    Science.gov (United States)

    Fan, Yuan; Ren, Chang-Zhong; Li, Pin-Fang; Ren, Tu-Sheng

    2011-11-01

    This paper monitored the oat growth and cation absorption characteristics on a saline-alkali soil in the Baicheng region of Jilin Province under low, medium, and high levels of salt stress. No significant differences were observed in the shoot growth and yield components under the three levels of salt stress, but the root biomass and root/shoot ratio decreased significantly with increasing salt stress level. At maturing stage, the root/shoot ratio under medium and high salt stresses was 77.2% and 64.5% of that under low salt stress, respectively. Under the three levels of salt stress, the K+/Na+ and Ca2+/Na+ ratios in oat plant had significant differences at trefoil stage, but no significant differences at heading stage. With the increase of salt stress level, the cation absorption selectivity coefficient of oat at filling stage decreased significantly, but the transportation selectivity coefficient had no significant difference under the three levels of stress. It was concluded that oat could adapt to the salt and alkali stress of soda-alkaline soil to some extent, and the adaptation capability decreased with the increasing level of stress. The decrease of oat root biomass and the stronger ion selective absorption capacity at heading stage under salt and alkali stress could benefit the shoot growth and yield components of oat. PMID:22303664

  6. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts.

    Science.gov (United States)

    Chen, Fangfang; Forsyth, Maria

    2016-07-28

    Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions. PMID:27375042

  7. Transport properties of alkali metal doped fullerides

    International Nuclear Information System (INIS)

    We have studied the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C60 phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, Tc, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C60 phonons as 5 K, which is much lower as compared to reported Tc (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity

  8. Transport properties of alkali metal doped fullerides

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Daluram, E-mail: daluramyadav@gmail.com; Yadav, Nishchhal, E-mail: somyadav@gmail.com [School of studies in Physics, Vikram University, Ujjain (M.P) India (India)

    2015-07-31

    We have studied the intercage interactions between the adjacent C{sub 60} cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C{sub 60} phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, T{sub c}, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C{sub 60} phonons as 5 K, which is much lower as compared to reported T{sub c} (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity.

  9. Heat transfer characteristics of alkali metals flowing across tube banks

    International Nuclear Information System (INIS)

    For the purpose of getting heat transfer coefficients of alkali metals flowing across tube banks at an acceptable level, we propose to use an inviscid-irrotational flow model, which is based on our flow visualization experiment. We show that the heat transfer coefficients obtained for the condition where only the test rod is heated in tube banks considerably differ from those obtained for the condition where all the rods are heated, because of interference between thick thermal boundary layers of alkali metals. We also confirm that the analytical values obtained by this flow model are in a reasonable agreement with experimental values. (author)

  10. Electron Mean-Free Paths in the Alkali Metals

    OpenAIRE

    Wertheim, G.K.; Riffe, D. Mark; Smith, N.V.; Citrin, P. H.

    1992-01-01

    Photoemission data in which the signal from the first atomic layer is well resolved from that of the bulk are used to determine accurately the kinetic-energy dependence of the inelastic-electron mean free path in the alkali metals. At the higher kinetic energies, the data are in very good agreement with the theory of Penn. Below about 10 eV, the mean free path in the heavier alkali metals drops markedly below the theoretical values. This is attributed to electron decay processes involvi...

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

    OpenAIRE

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

    2016-01-01

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

  12. Synthesis and Characterization of Novel Ternary and Quaternary Alkali Metal Thiophosphates

    KAUST Repository

    Alahmary, Fatimah S.

    2014-05-01

    The ongoing development of nonlinear optical (NLO) crystals such as coherent mid-IR sources focuses on various classes of materials such as ternary and quaternary metal chalcophosphates. In case of thiophosphates, the connection between PS4-tetrahedral building blocks and metals gives rise to a broad structural variety where approximately one third of all known ternary (A/P/S) and quaternary (A/M/P/S) (A = alkali metal, M = metal) structures are acentric and potential nonlinear optical materials. The molten alkali metal polychalcophosphate fluxes are a well-established method for the synthesis of new ternary and quaternary thiophosphate and selenophosphate compounds. It has been a wide field of study and investigation through the last two decades. Here, the flux method is used for the synthesis of new quaternary phases containing Rb, Ag, P and S. Four new alkali metal thiophosphates, Rb4P2S10, RbAg5(PS4), Rb2AgPS4 and Rb3Ag9(PS4)4, have been synthesized successfully from high purity elements and binary starting materials. The new compounds were characterized by single crystal and powder X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-VIS), Raman spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). These compounds show interesting structural variety and physical properties. The crystal structures feature 3D anionic framework built up of PS4 tetrahedral units and charge balanced by Ag and alkali metal cations. All prepared compounds are semiconductors with band gap between 2.3 eV to 2.6 eV and most of them are thermally stable up to 600ºC.

  13. Aqueous alkali metal hydroxide insoluble cellulose ether membrane

    Science.gov (United States)

    Hoyt, H. E.; Pfluger, H. L. (Inventor)

    1969-01-01

    A membrane that is insoluble in an aqueous alkali metal hydroxide medium is described. The membrane is a resin which is a water-soluble C2-C4 hydroxyalkyl cellulose ether polymer and an insolubilizing agent for controlled water sorption, a dialytic and electrodialytic membrane. It is particularly useful as a separator between electrodes or plates in an alkaline storage battery.

  14. Structural models for alkali-metal complexes of polyacetylene

    Science.gov (United States)

    Murthy, N. S.; Shacklette, L. W.; Baughman, R. H.

    1990-02-01

    Structural models for a stage-2 complex are proposed for polyacetylene doped with less than about 0.1 potassium or rubidium atoms per carbon. These structures utilize as a basic motif an alkali-metal column surrounded by four planar-zig-zag polyacetylene chains, a structure found at the highest dopant levels. In the new stage-2 structures, each polyacetylene chain neighbors only one alkali-metal column, so the phase contains four polymer chains per alkali-metal column. Basic structural aspects for stage-1 and stage-2 structures are now established for both potassium- and rubidium-doped polyacetylene. X-ray-diffraction and electrochemical data show that undoped and doped phases coexist at low dopant concentrations (<0.06 K atom per C). X-ray-diffraction data, down to a Bragg spacing of 1.3 Å, for polyacetylene heavily doped with potassium (0.125-0.167 K atom per C) is fully consistent with our previously proposed stage-1 tetragonal unit cell containing two polyacetylene chains per alkali-metal column. There is no evidence for our samples requiring a distortion to a monoclinic unit cell as reported by others for heavily doped samples. The nature of structural transformations and the relationship between structure and electronic properties are discussed for potassium-doped polyacetylene.

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

    Science.gov (United States)

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-08-01

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

  16. Analytical potentialities of an AI-05 instrument for capillary electrophoresis in the determination of metal cations

    International Nuclear Information System (INIS)

    The analytical potentialities of an AI-05 instrument for capillary zone electrophoresis were examined using the determination of alkali, alkaline earth, and transition metal cations as an example. The plot of the analytical signal of Sr2+ against the concentration of the sample was linear within the range 1 x 10-5 - 1 x 10-4 M. The phenomenon of discrimination of the ionic composition of a sample in the electromigration method of sample injection is discussed. The time taken to separate a mixture of metal cations (M = K, Na, Mg, Sr, Ca, Cd, Co, Ni and Zn) was 16 min

  17. Apparatus for use in a liquid alkali metal environment

    International Nuclear Information System (INIS)

    Apparatus is described for use in a liquid alkali metal environment consisting of components having complementary bearing surfaces in which one of the components has a bearing surface of stainless steel and another of the components has an aluminised complementary bearing surface. Examples are given of the use of the invention in heat exchange apparatus in liquid metal cooled fast breeder reactors; one example is in connection with the fuel subassembly in such a reactor. (U.K.)

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

    International Nuclear Information System (INIS)

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

  19. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    Prasenjit Sen

    2010-04-01

    Electronic and magnetic structures of (1 0 0) films of K and Cs, having thicknesses of one to seven layers, are calculated within the plane-wave projector augmented wave (PAW) formalism of the density functional theory (DFT), using both local spin density approximation (LSDA) and the PW91 generalized gradient approximation (GGA). Only a six-layer Cs film is found to have a ferromagnetic (FM) state which is degenerate with a paramagnetic (PM) state within the accuracy of these calculations. These results are compared with those obtained from calculations on a finite-thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films and bulk hosts are also discussed.

  20. Alkali Metal Coolants. Proceedings of the Symposium on Alkali Metal Coolants - Corrosion Studies and System Operating Experience

    International Nuclear Information System (INIS)

    Proceedings of a Symposium organized by the IAEA and held in Vienna, 28 November - 2 December 1966. The meeting was attended by 107 participants from 16 countries and two international organizations. Contents: Review papers (2 papers); Corrosion of steels and metal alloys (6 papers); Mass transfer in alkali metal systems, behaviour of carbon (5 papers); Effects of sodium environment on mechanical properties of materials (3 papers); Effect of water leakage into sodium systems (2 papers); Design-and operation of testing apparatus (6 papers); Control, measurements and removal of impurities (13 papers); Corrosion by other alkali metals: NaK, K, Li, Cs (6 papers); Behaviour of fission products (3 papers). Each paper is in its original language (32 English, 6 French and 8 Russian) and is preceded by an abstract in English and one in the original language if this is not English. Discussions are in English. (author)

  1. Chemical compatibility of structural materials in alkali metals

    International Nuclear Information System (INIS)

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures in the range that are of interest for International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal-environments

  2. Chemical compatibility of structural materials in alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L.; Haglund, R. [Argonne National Lab., Chicago, IL (United States)] [and others

    1995-04-01

    The objectives of this task are to (a) evaluate the chemical compatibility of structural alloys such as V-5 wt.%Cr-5 wt.%Ti alloy and Type 316 stainless steel for application in liquid alkali metals such as lithium and sodium-78 wt.% potassium (NaK) at temperatures in the range that are of interest for International Thermonuclear Experimental Reactor (ITER); (b) evaluate the transfer of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen between structural materials and liquid metals; and (c) evaluate the effects of such transfers on the mechanical and microstructural characteristics of the materials for long-term service in liquid-metal-environments.

  3. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated carboxylic acid alkali... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under...

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

    International Nuclear Information System (INIS)

    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) 1H-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+, Ca2+, Pb2+ and Mn2+ 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+, Ba2+, Zn2+ and Hg2+. 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+, Ba2+, Cu2+ and Hg2+ were noted. (author)

  5. Synthesis and Structural Characterization of Alkali Metal Guanidinates

    Institute of Scientific and Technical Information of China (English)

    LUO,Yun-Jie; YAO,Ying-Ming; ZHANG,Yong; SHEN,Qi

    2007-01-01

    Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides,MN(SiMe3)2(M=Li or Na)in hexane or THF produced the alkali metal guanidinates{(j-PrN)2C[N(SiMe3)2]Li}2(1)and{(i-PrN)2C[N(SiMe3)2]Na(THF)}2(2)in nearly quantitative yields.Both complexes 1 and 2 were well characterized by elemental analysis,IR spectra,1H and 13C NMR spectra,and X-ray diffraction.It was found that the guanidinates adopt different coordination modes in these complexes.

  6. Polarizabilities and hyperpolarizabilities of the alkali metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Fuentealba, P. (Chile Univ., Santiago (Chile). Departamento de Fisica and Centro de Mecanica Cuantica Aplicada (CMCA)); Reyes, O. (Chile Univ., Santiago (Chile). Dept. de Fisica)

    1993-08-14

    The electric static dipole polarizability [alpha], quadrupole polarizability C, dipole-quadrupole polarizability B, and the second dipole hyperpolarizability [gamma] have been calculated for the alkali metal atoms in the ground state. The results are based on a pseudopotential which is able to incorporate the very important core-valence correlation effect through a core polarization potential, and, in an empirical way, the main relativistic effects. The calculated properties compare very well with more elaborated calculations for the Li atom, excepting the second hyperpolarizability [gamma]. For the other atoms, there is neither theoretical nor experimental information about most of the higher polarizabilities. Hence, the results of this paper should be seen as a first attempt to give a complete account of the series expansion of the interaction energy of an alkali metal atom and a static electric field. (author).

  7. Inner-shell excitation of alkali-metal atoms

    International Nuclear Information System (INIS)

    Inner-shell excitation of alkali-metal atoms, which leads to auto-ionization, is reviewed. The validity of quantum mechanical approximation is analyzed and the importance of exchange and correlation is demonstrated. Basic difficulties in making accurate calculations for inner-shell excitation process are discussed. Suggestions are made for further study of inner-shell process in atoms and ions. (author). 26 refs, 4 figs, 1 tab

  8. Enthalpic Interaction for α-Amino Acid with Alkali Metal Halides in Water

    Institute of Scientific and Technical Information of China (English)

    LU,Yan(卢雁)

    2004-01-01

    The studies of the enthalpic interaction parameters, hxy, hxyy and hxxv, of alkali metal halides with glycine,α-alanine and α-aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the α-amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt's effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxy with the radius of cations is not evident. The value of hxyy will increase with the increase of the radii of the ions. As the increase of the number of carbon atoms of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α-alanine for the ions which have small size. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.

  9. Charge oscillations and structure for alkali-metal-doped polyacetylene

    Science.gov (United States)

    Baughman, R. H.; Murthy, N. S.; Eckhardt, H.; Kertesz, M.

    1992-11-01

    predictions for oligomers, and good agreement is obtained between calculated and observed x-ray photoelectron spectra for sodium-doped polyacetylene. Emphasis is placed on the results of crystallographic studies of alkali-metal-doped polyacetylene and on the relationship between the experimentally derived symmetry breaking in interchain packing and the molecular symmetry breaking predicted by theory. Since presently available experimental data are insufficient for complete determination of structure, the present theoretical results can be useful for refinements in the interpretation of these data, as well as for refined crystal-packing calculations.

  10. Dissolution of metallic uranium in alkalis

    International Nuclear Information System (INIS)

    The dissolution of U metallic foils has been studied in the framework of the development of an improved 99Mo-production process. The best conditions for the dissolution of uranium foils of approximately 150 μm are the following: a) NaClO concentrations of 0.20 and 0.23 M with NaOH of 0.27 and 0.31 M respectively; b) temperature of the solution, 70 C degrees; c) volume of the solution, 15 ml / cm2 of uranium foil; d) dissolution time, 30 minutes. (author)

  11. Alkali Metal Ion Complexes with Phosphates, Nucleotides, Amino Acids, and Related Ligands of Biological Relevance. Their Properties in Solution.

    Science.gov (United States)

    Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Lando, Gabriele; Milea, Demetrio; Sammartano, Silvio

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand). PMID:26860301

  12. Spectroscopy and interactions of metal and metal cation complexes

    OpenAIRE

    Plowright, Richard J.

    2010-01-01

    The work in this thesis looks at the spectroscopy and interactions of metals and metal cation complexes. There are two aspects of this vast subject that are considered: the electronic spectroscopy of Au-RG complexes and the ion-molecule chemistry of metals important in the mesosphere-lower thermosphere (MLT) region of the atmosphere. The spectroscopy of the molecular states in the vicinity of the strong Au 2P3/2, 1/2 ← 2S1/2 atomic transition, have been studied for the Au-RG (RG = Ne, Ar...

  13. Method for preparation of melts of alkali metal chlorides with highly volatile polyvalent metal chlorides

    International Nuclear Information System (INIS)

    A method for production of alkali metal (Cs, Rb, K) chloride melts with highly volatile polyvalent metal chlorides is suggested. The method consists, in saturation of alkali metal chlorides, preheated to the melting point, by volatile component vapours (titanium tetrachloride, molybdenum or tantalum pentachloride) in proportion, corresponding to the composition reguired. The saturation is realized in an evacuated vessel with two heating areas for 1-1.5 h. After gradual levelling of temperature in both areas the product is rapidly cooled. 1 fig.; 1 tab

  14. Optical response of alkali metal atoms confined in nanoporous glass

    International Nuclear Information System (INIS)

    We study the influence of optical radiation on adsorption and desorption processes of alkali metal atoms confined in nanoporous glass matrices. Exposure of the sample to near-IR or visible light changes the atomic distribution inside the glass nanopores, forcing the entire system to evolve towards a different state. This effect, due to both atomic photodesorption and confinement, causes the growth and evaporation of metastable nanoparticles. It is shown that, by a proper choice of light characteristics and pore size, these processes can be controlled and tailored, thus opening new perspectives for fabrication of nanostructured surfaces. (nanoobjects)

  15. Quasiparticle electronic band structure of the alkali metal chalcogenides

    Directory of Open Access Journals (Sweden)

    S.V. Syrotyuk

    2015-09-01

    Full Text Available The electronic energy band spectra of the alkali metal chalcogenides M2A (M: Li, Na, K, Rb; A: O, S, Se, Te have been evaluated within the projector augmented waves (PAW approach by means of the ABINIT code. The Kohn-Sham single-particle states have been found in the GGA framework. Further, on the basis of these results the quasiparticle energies of electrons as well as the dielectric constants were obtained in the approximation GW. The calculations based on the Green's function have been originally done for all the considered M2A crystals, except Li2O.

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  18. On metal oxide solubilities in some molten alkali metal bromides at T = 973 K

    International Nuclear Information System (INIS)

    Highlights: • Solubility products of MeO oxides in KBr–NaBr and KBr–LiBr eutectics are presented. • Correlation between radius of cation entering in oxide and its solubility is found. • Melt acidity increases in CsBr − KBr → KBr − NaBr → KBr − LiBr sequence. • The common oxoacidity scale of alkali metal chlorides and bromides is constructed. - Abstract: Reactions of Me2+ cations with O2− in molten (KBr + NaBr) (0.5:0.5) and (KBr + LiBr) (0.4:0.6) mixtures at T = 973 K were studied by potentiometric titration method using Pt(O2)|ZrO2(Y2O3) indicator electrode. In the former melt, the set of cations available for investigation was wide enough (Me = Sr, Ca, Mn, Co, Ni and Pb) and the corresponding solubility product indices (pKs,MeO, molalities) were found to be (3.81 ± 0.3) (SrO), (5.00 ± 0.3) (CaO), (7.85 ± 0.3) (MnO), (8.80 ± 0.1) (CoO), (9.72 ± 0.04) (NiO) and (5.20 ± 0.3) (PbO). A correlation between pKs,MeO and the polarisation action of the metal cation by Goldschmidt (ZerMe2+-2) was obtained. The oxide solubilities on the mole fraction scale were shown to be close to those obtained in molten (KCl + NaCl) equimolar mixture. On the basis of the solubility data the oxobasicity index (primary medium effect for oxide ion) for the (KBr + NaBr) melt was estimated as pI{KBr–LiBr} = −0.24. Due to considerable oxoacidic properties of Li+ cation in the molten (KBr + LiBr) eutectic, it was possible to study only three from the above cations (Me = Mn, Co and Ni) and their pKs,MeO values were (4.36 ± 0.2), (5.19 ± 0.05) and (6.25 ± 0.03), respectively. Comparison with the corresponding data for (KBr + NaBr) equimolar mixture showed that the Li+-based melt dissolved all the studied oxides in more extent. On the basis of the data obtained, the oxobasicity index value pI{KBr−LiBr} was estimated as (3.01 ± 0.5), that was close to the similar parameter of the chloride analogue (KCl + LiCl) (3.36). The change of the constituent anion of the

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

    International Nuclear Information System (INIS)

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

  20. Work function of alkali metal-adsorbed molybdenium dichalcogenides

    Science.gov (United States)

    Kim, Sol; Jhi, Seung-Hoon

    2015-03-01

    The lowest work function of materials, reported so far over the last few decades, is an order of 1eV experimentally and theoretically. Designing materials that has work-function less than 1eV is essential in the thermionic energy conversion. To explore new low work function materials, we study MoX2(X =S, Se, Te) adsorbed with alkali metals (Li, Na, K, Rb and Cs), and investigate the charge transfer, the formation of surface dipole, and the change in work function using first-principles calculations. It is found that the charge transfer from alkali metals to MoX2substrates decreases as the atomic number of adsorbates increases. Regardless of the amount of the charge transfer, K on MoTe2 exhibits the biggest surface dipole moment, which consequently makes the surface work function the lowest. We show that the formation of the surface dipole is a key in changing the work function. We find the trimerization of Mo atoms in the substrate with the lowest work-function, which may contribute to enhancement of the surface dipole.

  1. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    The Hanford Site, located northwest of the city of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials, as well as for activities associated with nuclear energy development. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. The 3718-F Alkali Metal Treatment and Storage Facility (3718-F Facility), located in the 300 Area, was used to store and treat alkali metal wastes. Therefore, it is subject to the regulatory requirements for the storage and treatment of dangerous wastes. Closure will be conducted pursuant to the requirements of the Washington Administrative Code (WAC) 173-303-610 (Ecology 1989) and 40 CFR 270.1. Closure also will satisfy the thermal treatment facility closure requirements of 40 CFR 265.381. This closure plan presents a description of the 3718-F Facility, the history of wastes managed, and the approach that will be followed to close the facility. Only hazardous constituents derived from 3718-F Facility operations will be addressed

  2. Alkali metal control over N-N cleavage in iron complexes.

    Science.gov (United States)

    Grubel, Katarzyna; Brennessel, William W; Mercado, Brandon Q; Holland, Patrick L

    2014-12-01

    Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber-Bosch process, there is still ambiguity about the number of Fe atoms involved during the N-N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe-N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N-N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N-N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2. PMID:25412468

  3. Effects of metallic cations in the beryl flotation

    International Nuclear Information System (INIS)

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.)

  4. Freezing of liquid alkali metals as screened ionic plasmas

    International Nuclear Information System (INIS)

    The relationship between Wigner crystallization of the classical ionic plasma and the liquid-solid transition of alkali metals is examined within the density wave theory of freezing. Freezing of the classical plasma on a rigid neutralizing background into the bcc structure is first re-evaluated, in view of recent progress in the determination of its thermodynamic functions by simulation and of the known difficulties of the theory relating to the order parameter at the (200) star of reciprocal lattice vectors. Freezing into the fcc structure is also considered in this context and found to be unfavoured. On allowing for long-wavelength deformability of the background, the ensuing appearance of a volume change on freezing into the bcc structure is accompanied by reduced stability of the fluid phase and by an increase in the entropy of melting. Freezing of alkali metals into the bcc structure is next evaluated, taking their ionic pair structure as that of an ionic plasma reference fluid screened by conduction electrons and asking that the correct ionic coupling strength at liquid-solid coexistence should be approximately reproduced. The ensuring values of the volume and entropy changes across the phase transition, as estimated from the theory by two alternative routes, are in reasonable agreement with experiment. The order parameters of the phase transition, excepting the (200) one, conform rather closely to a Gaussian behaviour and yield a Lindemann ratio in reasonable agreement with the empirical value for melting of bcc crystals. It is suggested that ionic ordering at the (200) star in the metal may be (i) assisted by medium range ordering in the conduction electrons, as indicated by differences in X-ray and neutron diffraction intensities from the liquid, and/or (ii) quite small in the hot bcc solid. Such a possible premelting behaviour of bcc metals should be worth testing experimentally by diffraction. (author). 48 refs, 1 fig., 1 tab

  5. Alkali Metal Complexes: Mixed Ligand Complexes of Some Alkali Metal Salts of Some Organic Acids with Isonitroso-PMethylace to phenone

    Directory of Open Access Journals (Sweden)

    O.P. Gupta

    2016-02-01

    Full Text Available A number of mixed ligand complexes of alkali metal salts of o-nitrophenol,2,4-dinitrophenol, 2,4,6,- trinitrophenol, 1-nitroso-2- naphthol and 8- hydroxyquinoline with Insoniroso–p methylacetopheone have been synthesized in absolute ethanol & characterized by elemental analysis and I .B. spectral data. Their I.R spectral data indicate the presence of hydrogen bonding in them, which many be one of the dominant factors of their stability. Further appreciable shift in 1650 cm-1 band (possibly vC=O and 1600 cm-1 band (possibly vC=NSuggests their coordination behavior in these mixed ligand complexes The reactions that take place in natural systems are highly specific and selective. Alkali metal ions actively participate in most of the reaction occurring in the biological systems, which are dominated by mixed ligand complexes. Studies of such mixed ligand complexes of alkali metals can threw light in understanding the role and mechanism of selective absorption of alkali metals ions by plants Coordinating ability of alkali metal with isonitrosoacetophenone1-2 and transition metals with isonitrosoacetophenone3 and isonitroso-p-methylacetophenone4 have been reported earlier. In the present paper we report the mixed ligand complexes of alkali metal salts having the general formula ML.HL, ‘ where M=Li, Na & K and L=deprotonated o- nitrophenol, 2,4 dinitrophenol, 2, 4, 6- trinitrophenol, 1-nitroso-2-naphthol or 8- hydroxquinoline; HL’= p -MeHINAP (isonitroso-p-methylacetophenone.

  6. 50 years of superbases made from organolithium compounds and heavier alkali metal alkoxides

    Czech Academy of Sciences Publication Activity Database

    Lochmann, Lubomír; Janata, Miroslav

    2014-01-01

    Roč. 12, č. 5 (2014), s. 537-548. ISSN 1895-1066 R&D Projects: GA ČR GAP106/12/0844 Institutional support: RVO:61389013 Keywords : superbases * heavier alkali metal compounds * lithium -heavier alkali metal interchange Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.329, year: 2013

  7. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    Energy Technology Data Exchange (ETDEWEB)

    None

    1991-12-01

    Since 1987, Westinghouse Hanford Company has been a major contractor to the U.S. Department of Energy-Richland Operations Office and has served as co-operator of the 3718-F Alkali Metal Treatment and Storage Facility, the waste management unit addressed in this closure plan. The closure plan consists of a Part A Dangerous waste Permit Application and a RCRA Closure Plan. An explanation of the Part A Revision (Revision 1) submitted with this document is provided at the beginning of the Part A section. The closure plan consists of 9 chapters and 5 appendices. The chapters cover: introduction; facility description; process information; waste characteristics; groundwater; closure strategy and performance standards; closure activities; postclosure; and references.

  8. Ion-exchange behavior of alkali metals on treated carbons

    International Nuclear Information System (INIS)

    The ion-exchange behavior of trace quantities of the alkali-metal ions sodium and cesium, on activated carbon impregnated with zirconium phosphate (referred to here as ZrP), was studied. Impregnated carbon had twice as much ion-exchange activity as unimpregnated, oxidized carbon, and 10 times as much as commercial activated carbons. The distribution coefficient of sodium increased with increasing pH; the distribution coefficient of cesium decreased with increasing pH. Sodium and cesium were separated with an electrolytic solution of 0.1 M HCl. Preliminary studies indicated that 0.2 M potassium and cesium can also be separated. Distribution coefficients of the supported ZrP were determined by the elution technique and agreed within 20% of the values for pure ZrP calculated from the literature

  9. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    Science.gov (United States)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  10. Density dependence of the diffusion coefficient of alkali metals

    International Nuclear Information System (INIS)

    The effect of density on transport coefficients of liquid Li, Na and K at high temperatures using the method of Molecular Dynamics simulation has been studied. Simulation of these liquid alkali metals were carried out with 800 particles in simulation boxes with periodic boundary conditions imposed. In order to test the reliability of the interatomic potential used in the calculations, experimental data on the structural properties were compared with calculated results. The calculations showed a linear relationship between the density and the diffusion coefficient in all the systems investigated except in lithium, where, due to the small size of the atom, standard molecular dynamics simulation method may not be appropriate for calculating the properties of interest. (author)

  11. Momentum densities and Compton profiles of alkali-metal atoms

    International Nuclear Information System (INIS)

    It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from 3Li to 37Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton profile are found to be in good agreement with the results of more detailed configuration-interaction calculations for the atom 3Li. Similar results for 11Na, 19K and 37Rb are compared with the corresponding Hartree-Fock-Roothan values only, for want of data from other realistic calculations. (author)

  12. Alkali metal thermoelectric conversion (AMTEC) technology status review

    International Nuclear Information System (INIS)

    The Alkali Metal Thermoelectric Converter (AMTEC) or sodium heat engine has been the subject of experimental and systems investigations to assess its potential and feasibility for several space and terrestrial power applications. AMTEC is a thermally regenerative electrochemical system operating between a high temperature reservoir at 900-1400K and a sodium condenser at 400-BOOK. Its operation is based on the sodium ion conductor beta-alumina solid electrolyte(BASE), where thermal to electric conversion efficiencies of 20-40% have been predicted for practical systems. Other AMTEC characteristics that make it attractive for space applications are compactness, light weight, no moving parts, modularity and long lifetime potential. This paper reviews AMTEC operating principles and technical challenges, reports on recent electrode research results, and summarizes the status of AMTEC device experiments at JPL and elsewhere. Also, updated projections for AMTEC space nuclear power system characteristics is presented

  13. Relativistic optimized effective potential method-application to alkali metals.

    Science.gov (United States)

    Ködderitzsch, D; Ebert, H; Akai, H; Engel, E

    2009-02-11

    We present a relativistic formulation of the optimized effective potential method (ROEP) and its implementation within the Korringa-Kohn-Rostoker multiple scattering formalism. The scheme is an all-electron approach, treating core and band states formally on the same footing. We use exact exchange (EXX) as an approximation to the exchange correlation functional. Numerical four-component wavefunctions for the description of core and valence electrons and the corresponding ingredients of the ROEP integral equation are employed. The exact exchange expression for the valence states is reformulated in terms of the electronic Green's function that in turn is evaluated by making use of multiple scattering formalism. We present and discuss the application of the formalism to non-magnetic alkali metals. PMID:21715911

  14. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan

    International Nuclear Information System (INIS)

    Since 1987, Westinghouse Hanford Company has been a major contractor to the U.S. Department of Energy-Richland Operations Office and has served as co-operator of the 3718-F Alkali Metal Treatment and Storage Facility, the waste management unit addressed in this closure plan. The closure plan consists of a Part A Dangerous waste Permit Application and a RCRA Closure Plan. An explanation of the Part A Revision (Revision 1) submitted with this document is provided at the beginning of the Part A section. The closure plan consists of 9 chapters and 5 appendices. The chapters cover: introduction; facility description; process information; waste characteristics; groundwater; closure strategy and performance standards; closure activities; postclosure; and references

  15. Theoretical investigation of the interaction of cytosine and its tautomers with alkali metals

    International Nuclear Information System (INIS)

    Quantum-chemical calculations have been applied in order to explore the interaction of alkali metals (M=Li-Cs) with cytosine and its tautomers. The optimized geometries, harmonic vibrational frequencies, and the energies of cytosine, metallated cytosine, and its tautomers have been calculated. The calculations show that metallated cytosine is more stable than non metallated one. The stability of metallated cytosine decreases with the growth of atomic number of alkali metals. Estimated charge on the metals demonstrates that there is some covalency in the metal-ligand interaction, especially in the Li+ system

  16. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca2+, Li+, Na+, NH4+) at concentrations up to 25 mM. This......We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...

  17. Elimination technique for alkali metal ion adducts from an electrospray ionization process using an on-line ion suppressor

    OpenAIRE

    NOZAKI, Kazuyoshi; TARUI, Akira; OSAKA, Issey; Kawasaki, Hideya; ARAKAWA, Ryuichi; 荒川, 隆一

    2010-01-01

    The effects of an on-line ion suppressor device on alkali metal ion adduct formations of the model compound tacrolimus were investigated. The base peak ion in the positive ion ESI-MS spectrum of tacrolimus was a sodium ion adduct, [M+Na]+. On the other hand, an ammonium ion adduct, [M+NH4]+, was the base peak ion in the full-scan mass spectrum of tacrolimus with a cation-exchange suppressor resin, and both [M+Na]+ and [M+K]+ were eliminated. These results indicate that the combination of an o...

  18. Decomplexing metallic cations from metallo-organic compounds

    OpenAIRE

    Melian, C.I.; Kapteijn F.; Moulijn, J.A.

    2006-01-01

    The invention is directed to a process for liberating metallic cations from metallo-organic compounds, said process comprising contacting an aqueous solution of the metallo-organic compound with an oxidising agent, thereby oxidising the organic component and obtaining the free cation

  19. Properties of alkali metal atoms deposited on a MgO surface: a systematic experimental and theoretical study.

    Science.gov (United States)

    Finazzi, Emanuele; Di Valentin, Cristiana; Pacchioni, Gianfranco; Chiesa, Mario; Giamello, Elio; Gao, Hongjun; Lian, Jichun; Risse, Thomas; Freund, Hans-Joachim

    2008-01-01

    The adsorption of small amounts of alkali metal atoms (Li, Na, K, Rb, and Cs) on the surface of MgO powders and thin films has been studied by means of EPR spectroscopy and DFT calculations. From a comparison of the measured and computed g values and hyperfine coupling constants (hfccs), a tentative assignment of the preferred adsorption sites is proposed. All atoms bind preferentially to surface oxide anions, but the location of these anions differs as a function of the deposition temperature and alkali metal. Lithium forms relatively strong bonds with MgO and can be stabilized at low temperatures on terrace sites. Potassium interacts very weakly with MgO and is stabilized only at specific sites, such as at reverse corners where it can interact simultaneously with three surface oxygen atoms (rubidium and cesium presumably behave in the same way). Sodium forms bonds of intermediate strength and could, in principle, populate more than a single site when deposited at room temperature. In all cases, large deviations of the hfccs from the gas-phase values are observed. These reductions in the hfccs are due to polarization effects and are not connected to ionization of the alkali metal, which would lead to the formation of an adsorbed cation and a trapped electron. In this respect, hydrogen atoms behave completely differently. Under similar conditions, they form (H(+))(e(-)) pairs. The reasons for this different behavior are discussed. PMID:18381711

  20. Structural properties of low-density liquid alkali metals

    Indian Academy of Sciences (India)

    A Akande; G A Adebayo; O Akinlade

    2005-12-01

    The static structure factors of liquid alkali metals have been modelled at temperatures close to their melting points and a few higher temperatures using the reverse Monte Carlo (RMC) method. The positions of 5000 atoms in a box, with full periodicity, were altered until the experimental diffraction data of the structure factor agrees with the associated model structure factor within the errors. The model generated is then analysed. The position of the first peak of the pair distribution function () does not show any significant temperature dependence and the mean bond lengths can be approximated within an interval of 3.6–5.3 Å, 4.5–6.6 Å, 4.8–6.7 Å and 5.1–7.3 Å for Na, K, Rb and Cs respectively. The cosine bond distributions show similar trend with the flattening up of the first peak with increase in temperature. In addition, the coordination numbers of these liquid metals are high due to the presence of non-covalent bonding between them. On the average, we surmise that the coordination number decreases with increase in temperature.

  1. Field emission properties of capped carbon nanotubes doped by alkali metals:a theoretical investigation

    Institute of Scientific and Technical Information of China (English)

    Jin Lei; Fu Hong-Gang; Xie Ying; Yu Hai-Tao

    2012-01-01

    The electronic structures and field emission properties of capped CNT55 systems with or without alkali metal atom adsorption were systematically investigated by density functional theory calculation.The results indicate that the adsorption of alkali metal on the center site of a CNT tip is energetically favorable.In addition,the adsorption energies increase with the introduction of the electric field.The excessive negative charges on CNT tips make electron emittance much easier and result in a decrease in work function.Furthermore,the inducing effect by positively charged alkali metal atoms can be reasonably considered as the dominant reason for the improvement in field emission properties.

  2. Method and composition for testing for the presence of an alkali metal

    International Nuclear Information System (INIS)

    A method and composition for detecting the presence of an alkali metal on the surface of a body such as a metal plate, tank, pipe or the like is provided. The method comprises contacting the surface with a thin film of a liquid composition comprising a light-colored pigment, an acid-base indicator, and a nonionic wetting agent dispersed in a liquid carrier comprising a minor amount of water and a major amount of an organic solvent selected from the group consisting of the lower aliphatic alcohols, ketones and ethers. Any alkali metal present on the surface in elemental form or as an alkali metal hydroxide or alkali metal carbonate will react with the acid-base indicator to produce a contrasting color change in the thin film, which is readily discernible by visual observation or automatic techniques

  3. 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)

  4. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-08-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  5. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-05-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  6. Modification of alkali metals on silicon-based nanoclusters: An enhanced nonlinear optical response

    Science.gov (United States)

    Li, Xiaojun; Han, Quan; Yang, Xiaohui; Song, Ruijuan; Song, Limei

    2016-08-01

    Structures, chemical stabilities and nonlinear optical properties of alkali metals-adsorbed niobium-doped silicon (M@SinNb+) clusters are investigated using the DFT methods. The alkali metals prefer energetically to be attached as bridged bond rather than M-Si single bond in most of optimized structures. Adsorption of alkali metals on doped silicon clusters gradually enhances their chemical stabilities with increasing cluster size. Noteworthily, the first hyperpolarizabilities (βtot) of the M@SinNb+ clusters, obtained by using the long-range corrected CAM-B3LYP functional, are large enough to establish their strong nonlinear optical behavior, especially for M@Si9Nb+ (M = Li, Na, and K), and the enhanced βtot ordering by alkali metals is Na > K > Li.

  7. Study on the electrode characteristics of alkali metal thermoelectric converter

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter utilizing the sodium ion conducting β''-alumina is a device to convert directly heat energy to electric energy. It is characterized by high conversion efficiencies, high power densities, no moving parts and low maintenance requirements. Because of these merits, AMTEC is one of the most promising candidate for aerospace power systems, remote power station and dispersed small scale power station. In this paper, the experimental results of the disk type cell and the theoretical considerations about internal resistances have been reported. The film electrode was made with a magnetron sputtering system. The open voltage of 0.98 V and the maximum power density of 0.38 W/cm2 at the sodium temperature of 1,073 K have been obtained. It became clear after the theoretical investigation on the internal resistance that the most largest internal resistance was the resistance of β''-alumina. And so, it is necessary to reduce the thickness of β''-alumina to improve the generating power densities. It was also clarified that the sodium gas flow in the small holes of molybdenum thin film electrode was a free molecular flow and the experimental results became agree well with the theoretical results considering the pressure rise due to this sodium free molecular flow. It was also necessary to develop the more porous and lower resistivity thin film electrodes because this pressure rise were fairly large. (author)

  8. Superconductivity of graphite intercalation compounds with alkali-metal amalgams

    International Nuclear Information System (INIS)

    Superconductivity of the alkali-metal amalgam graphite intercalation compounds of stage 1 (C4KHg, C4RbHg) and stage 2 (C8KHg, C8RbHg) has been studied as well as that of the pristine amalgams (KHg, RbHg). The transition temperatures are 0.73, 0.99, 1.90, and 1.40 K for C4KHg, C4RbHg, C8KHg, and C8RbHg, respectively. The critical-field anisotropy ratio H/sup parallel//sub c/2/H/sup perpendicular//sub c/2 is about 10 for the stage 1 and about 15 to 40 for the stage 2. It is argued that electrons in the intercalant bands rather than the graphitic bands play the main role in the superconductivity. An interesting feature is that the stage-2 compound, which has a lower density of states at the Fermi level, has a higher transition temperature than the corresponding state-1 compound

  9. Corrosion in alkali metal/molybdenum heat pipes

    International Nuclear Information System (INIS)

    Molybdenum/sodium (Mo/Na) and molybdenum/lithium (Mo/Li) heat pipes have been operated for long periods of time in a study of their resistance to failure by alkali metal corrosion. Some Mo/Na heat pipes have operated over 20,600 h at 1400 K without failure, while at least one similar heat pipe failed in less than 14 hours at 1435 K. Detailed post-mortem analyses which have been performed on three failed Mo/Na heat pipes all indicated impurity controlled corrosion of their evaporators. Impurities observed to be transported included carbon, oxygen, and silicon. A Mo/Li heat pipe that failed after 25,216 h of operation at 1700 K was also examined in detail. This failure was due to nickel impurities being transported to the evaporator resulting in perforation of the container tube by the formation of a low melting Mo-Ni alloy. Theoretical thermochemical calculations were conducted for these systems with the objective of corroborating the corrosion mechanisms in both types of heat pipes. The results of these calculations are in general agreement with the observed corrosion a phenomena

  10. Design of low work function materials using alkali metal-doped transition metal dichalcogenides

    Science.gov (United States)

    Kim, Sol; Lee, Man Young; Lee, Seong; Jhi, Seung-Hoon

    Engineering the work function is a key issue in surface science. Particularly, discovering the materials that have work functions less than 1eV is essential for efficient thermionic energy conversion. The lowest work function of materials, reported so far, is in a range of about 1eV. To design low work function materials, we chose MX2 (M =Mo and W; X =S, Se and Te) as substrates and alkali metals (Li, Na, K, Rb and Cs) as dopants, and studied their electronic structures, charge transfer, induced surface dipole moment, and work function using first-principles calculations. We found that the charge transfer from alkali metals to MX2 substrates decreases as the atomic radius of alkali metals increases. Regardless of the amount of the charge transfer, K on WTe2 exhibits the biggest surface dipole moment, which consequently makes the surface work function the lowest. Also, we found a correlation between the binding distance and the work function.

  11. Behavior of Alkali Metals and Ash in a Low-Temperature Circulating Fluidized Bed (LTCFB) Gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk;

    2016-01-01

    W and a 6 MW LTCFBgasifier. Of the total fuel ash entering the system, the largest fraction (40−50%) was retained in the secondary cyclone bottoms,while a lower amount (8−10%) was released as dust in the exit gas. Most of the alkali and alkaline earth metals were retained inthe solid ash, along with Si......, the low reactor temperature ensures that high-alkali biomass fuels canbe used without risk of bed defluidization. This paper presents the first investigation of the fate of alkali metals and ash in lowtemperaturegasifiers. Measurements on bed material and product gas dust samples were made on a 100 k...

  12. Quantum Chemical and FTIR Spectroscopic Studies on the Linkage Isomerism of Carbon Monoxide in Alkali-Metal-Exchanged Zeolites: A Review of Current Research

    Directory of Open Access Journals (Sweden)

    E. Garrone

    2002-07-01

    Full Text Available Abstract: When adsorbed (at a low temperature on alkali-metal-exchanged zeolites, CO forms both M(CO+ and M(OC+ carbonyl species with the extra-framework alkali-metal cation of the zeolite. Both quantum chemical and experimental results show that C-bondend adducts are characterized by a C−O stretching IR band at a frequency higher than that of 2143 cm-1 for free CO, while for O-bonded adducts this IR band appears below 2143 cm-1. The cation-CO interaction energy is higher for M(CO+ than for M(OC+ carbonyls, although the corresponding difference decreases substantially when going from Li+ to Cs+. By means of variable-temperature FTIR spectroscopy, this energy difference was determined for several alkali-metal cations, and the existence of a thermal equilibrium between M(CO+ and M(OC+ species was established. The current state of research in this field is reviewed here, with a view to gain more insight into the thermal isomerization process.

  13. Infrared spectroscopy of mass-selected metal carbonyl cations

    Science.gov (United States)

    Ricks, A. M.; Reed, Z. E.; Duncan, M. A.

    2011-04-01

    Metal carbonyl cations of the form M(CO)n+ are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom "tagged" analogs, M(CO)n(RG)m+, are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of "non-classical" carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V +, Nb + and Ta +), while uranium cations provide an example of an eight-coordinate carbonyl.

  14. Half metallic ferromagnetism in alkali metal nitrides MN (M = Rb, Cs): A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, A., E-mail: rrpalanichamy@gmail.com; Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com; Santhosh, M., E-mail: rrpalanichamy@gmail.com; Sudhapriyanga, G., E-mail: rrpalanichamy@gmail.com [Department of Physics, N.M.S.S.V.N College, Madurai, Tamilnadu-625019 (India); Kanagaprabha, S. [Department of Physics, Kamaraj College, Tuticorin, Tamil Nadu-628003 (India)

    2014-04-24

    The structural, electronic and elastic properties of two alkali metal nitrides (MN: M= Rb, Cs) are investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At ambient pressure the two nitrides are stable in ferromagnetic state with CsCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic in nature. A pressure-induced structural phase transition from CsCl to ZB phase is observed in RbN and CsN.

  15. Structural study and properties of the alkali metal, nitrosyl, and ammonium hepta- and octafluorouranates(VI)

    International Nuclear Information System (INIS)

    The thermal decomposition of the heptafluorouranates(VI) of the alkali metals is shown to take place in two steps. The first step gives the octafluorouranates(VI) and UF6, and the decomposition rate is noticeable at temperatures above 100, 130, 150, and 2100C for the Na, K, Rb, and Cs salts, respectively. The second step for Na2UF8 yields pure NaF and UF6 above 3000C, whereas the decomposition temperatures for the K, Rb, and Cs salts are above 300, 350, and 4000C, respectively. Depending on the decomposition conditions, F2 and M2UF7(M = K, Rb, Cs) or F2, UF6, and M3UF8 are formed. The heptafluorouranates(VI) of all the cations studied, except for ammonium, were shown to exhibit dimorphism. The parameters of their cubic form were obtained and are as follows: KUF7; a = 5.22 A; RbUF7; a = 5.385 A; CsUF7; a = 5.517 A; NOUF7; a = 5.334 A; NH4UF7; a = 5.393 A; NaUF7(fccub), a = 8.511 A, Z = 4. The x-ray pattern of the low-symmetry form of CsUF7 just below the solid transition temperature (15 +- 10C) was indexed with a tetragonal cell where a = 5.50 A and c = 5.37 A. The x-ray diagrams of the low symmetry form of the other MUF7 salts were not indexed, whereas those of the octafluorouranates were indexed with orthorhombic cells. The vibrational spectra of the hepta- and octafluorouranates were found to be very dependent on the temperature, and for the same temperature on the cation size. Some trends observed in this study, like the thermal decomposition temperatures or the relative symmetries, are thought to arise from the differences in the cation--anion interaction. This interaction is stronger with smaller cations, which results in more distorted anions, less ionic U--F bonds, and paradoxically less stable complexes

  16. Alkali and heavy metal emissions of the PCFB-process; Alkali- ja raskasmetallipaeaestoet PCFB-prosessista

    Energy Technology Data Exchange (ETDEWEB)

    Kuivalainen, R.; Eriksson, T.; Lehtonen, P. [Foster Wheeler Energia Oy, Karhula (Finland)

    1997-10-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed in Karhula R and D Center since 1986. As part of the development, 10 MW PCFB test facility was built in 1989. The test facility has been used for performance testing with different coal types through the years 1990-1995 in order to gain data for design and commercialization of the high-efficiency low-emission PCFB combustion technology. The main object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measurements were performed using plasma assisted method of TUT Laboratory of Plasma Technology and wet absorption method of VTT Energy. The measurements were carried out during three test campaigns at PCFB Test Facility in Karhula. In autumn 1995 both VTT and TUT methods were used. The measurements of the following test period in spring 1996 were performed by VTT, and during the last test segment in autumn 1996 TUT method was in use. During the last test period, the TUT instrument was used as semi-continuous (3 values/minute) alkali analyzer for part of the time. The measured Na concentrations were below 30 ppb(w) in all measured data points. The results of K were below 10 ppb(w). The accuracies of the both methods are about +50 % at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission. The measured emissions are at the same order of magnitude as the guideline emission limits estimated by gas turbine manufacturers

  17. Lattice-gas model for alkali-metal fullerides: face-centered-cubic structure

    OpenAIRE

    Udvardi, Laszlo; Szabo, Gyorgy

    1995-01-01

    A lattice-gas model is suggested for describing the ordering phenomena in alkali-metal fullerides of face-centered-cubic structure assuming the electric charge of alkali ions residing in either octahedral or tetrahedral interstitial sites is completely screened by the first-neighbor C_60 molecules. This approximation allows us to derive an effective ion-ion interaction. The van der Waals interaction between the ion and C_60 molecule is characterized by introducing an additional energy at the ...

  18. Enrichment of hydrogen isotopes while decomposition of alkali metal amalgams (Preprint No. CA-11)

    International Nuclear Information System (INIS)

    Sodium amalgam was prepared by electrolyzing caustic soda solution in a cell with flowing mercury as cathode. On decomposition of amalgam with aqueous sodium hydroxide solution in a denuder column packed with graphite pieces, the resultant hydrogen gas was depleted in deuterium. The alkali solution was enriched in deuterium content. The separation of the isotopes of some amalgam forming metals while decomposition of the amalgam of these metals with water has already been described. The separation is due to differential reaction rates of alkali metal amalgams with water containing light and heavy isotopes of hydrogen. However in the present investigation, the separation factor obtained is considerably higher than earlier reported due to possible chemical exchange between resultant hydrogen and the alkali metal hydroxide in presence of graphite surface and/or exchange of water with nascent hydrogen catalysed by OH- ions. (author). 18 refs., 3 tabs., 1 fig

  19. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    Science.gov (United States)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  20. Saturated vapor pressure above the amalgam of alkali metals in discharge lamps

    Science.gov (United States)

    Gavrish, S. V.

    2011-12-01

    A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

  1. Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.

    Science.gov (United States)

    Uzelac, Marina; Borilovic, Ivana; Amores, Marco; Cadenbach, Thomas; Kennedy, Alan R; Aromí, Guillem; Hevia, Eva

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2 SiMe3 )2 and the heavier alkali-metal alkyls M(CH2 SiMe3 ) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2 SiMe3 )3 ] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2 SiMe3 )3 ⋅C6 H6 }2 ] (2) and [{NaMn(CH2 SiMe3 )3 }2 (dioxane)7 ] (5); and to more complex supramolecular networks [{NaMn(CH2 SiMe3 )3 }∞ ] (1) and [{Na2 Mn2 (CH2 SiMe3 )6 (DABCO)2 }∞ ] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6 K2 Mn2 (CH2 SiMe3 )4 (O(CH2 )2 OCH=CH2 )2 }∞ ] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways. PMID:26916525

  2. Ionic conduction in alkali metal doped ZnFe/sub 2/O/sub 4/ compound

    International Nuclear Information System (INIS)

    Zinc ferric oxide (ZnFe/sub 2/O/sub 4/) has been synthesized by liquid phase chemical reaction from aqueous mixture of zinc chloride and ferric chloride in sodium hydroxide (4N) solution and effect of alkali metal on electrical characteristics was explored. The well characterized powder was pressed into pellets and dried at 80 degree C. Samples with alkali metal concentrations 10-100 ppm have been investigated to I-V measurements. The conductivity of pure compound (10-/sub 2/omega-cm)/sup-1/) lies in the semiconductor range but due to alkali metal doping the compound shows ionic conduction at room temperature. The ionic conduction is found to be increased as the dopant concentration increases.(author)

  3. Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid-graphene electrode interfaces.

    Science.gov (United States)

    Ivaništšev, Vladislav; Méndez-Morales, Trinidad; Lynden-Bell, Ruth M; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M; Fedorov, Maxim V

    2016-01-14

    In this work we study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion-electrode interactions in ionic liquids. We compare the interfacial behaviour of Li(+) and K(+) at a charged graphene sheet in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, and its mixtures with lithium and potassium tetrafluoroborate salts. Our results show that there are dense interfacial solvation structures in these electrolytes that lead to the formation of high free energy barriers for these alkali metal cations between the bulk and direct contact with the negatively charged surface. We show that the stronger solvation of Li(+) in the ionic liquid leads to the formation of significantly higher interfacial free energy barriers for Li(+) than for K(+). The high free energy barriers observed in our simulations can explain the generally high interfacial resistance in electrochemical storage devices that use ionic liquid-based electrolytes. Overcoming these barriers is the rate-limiting step in the interfacial transport of alkali metal ions and, hence, appears to be a major drawback for a generalised application of ionic liquids in electrochemistry. Some plausible strategies for future theoretical and experimental work for tuning them are suggested. PMID:26661060

  4. Thermochemistry of complex oxides of uranium(6), arsenic and alkali metals

    International Nuclear Information System (INIS)

    Standard reaction enthalpies for stoichiometric mixtures of mono-potassium orthoarsenate, uranium(6) and alkali metal nitrate oxides as well as mixtures of complex oxides of the M1AsUO6 (M1 = Li, Na, K, Rb, Cs) general formulas and potassium nitrate with hydrofluoric acid are determined in adiabatic calorimeter at the temperature of 298.15 K. Standard enthalpies for formation of complex oxides of uranium(6), arsenic and alkali metals at the temperature of 298.15 K are calculated by the obtained results. 8 refs., 1 tab

  5. Crystal-structural study of zirconium chelates with alkali metals of composition A2[Zr(Nta)2]·xH2O (A=Li, Na, K, Rb, Cs or CH3H6)

    International Nuclear Information System (INIS)

    Some zirconium complexes with nitrile triacetate and with alkali metal in the external sphere were studied crystalostructurally. Packing of complexes and extra-sphere cations was studied. Plane or slightly corrugated anion layers of two essentially different types arranged according to the principle of trigonal and square grids represent the standard element of crystal structure. Water molecules are located both in anion and cation layers. CN and coordination polyhedron of cations are different even in case of stereotype nature of reasons of their location in the interlayer space. In Cs-, Rb- and K- compounds polyhedrons of alkali metal form specific doubled chains. These compounds are not isomorphous ones and are characterized by a specific way of water molecule location. Structure of sodium compound differs fundamentally from other ones. Ionic conductivity may be expected in crystals. 4 refs., 6 figs., 2 tabs

  6. Theoretical study on the adsorption of carbon dioxide on individual and alkali-metal doped MOF-5s

    Science.gov (United States)

    Ha, Nguyen Thi Thu; Lefedova, O. V.; Ha, Nguyen Ngoc

    2016-01-01

    Density functional theory (DFT) calculations were performed to investigate the adsorption of carbon dioxide (CO2) on metal-organic framework (MOF-5) and alkali-metal (Li, K, Na) doped MOF-5s. The adsorption energy calculation showed that metal atom adsorption is exothermic in MOF-5 system. Moreover, alkali-metal doping can significantly improve the adsorption ability of carbon dioxide on MOF-5. The best influence is observed for Li-doping.

  7. Model for H-, D- production by hydrogen backscattering from alkali and alkali/transition-metal surfaces

    International Nuclear Information System (INIS)

    A model for H-, D- production by energetic particles reflecting from metal surfaces is discussed. The model employs the energy and angular distribution data derived from the Marlowe code. The model is applied to particles incident normally upon Cs, Ni, and Cs/Ni surfaces

  8. Phonon dispersion in alkali metals and their equiatomic sodium-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    Aditya M. VORA

    2008-01-01

    In the present article, the theoretical calcula-tions of the phonon dispersion curves (PDCs) of five alkali metals viz. Li, Na, K, Rb, Cs and their four equia-tomic sodium-based binary alloys viz. Na0.5Li0.5,Na0.5K0.5, Na0.5Rb0.5 and Na0.5Cs0.5 to second order in a local model potential is discussed in terms of the real-space sum of the Born yon Karman central force con-stants. Instead of the concentration average of the force constants of pure alkali metals, the pseudo-alloy-atom (PAA) is adopted to directly compute the force constants of the four equiatomic sodium based binary alloys and was successfully applied. The exchange and correlation functions due to the Hartree (H) and Ichimaru-Utsumi (IU) are used to investigate the influence of the screening effects. The phonon frequencies of alkali metals and their four equiatomic sodium-based binary alloys in the longit-udinal branch are more sensitive to the exchange and cor-relation effects in comparison with the transverse branches. The PDCs of pure alkali metals are found in qualitative agreement with the available experimental data. The frequencies in the longitudinal branch are sup-pressed rather due to IU-screening function than those due to static H-screening function.

  9. Modified PVA-CA blend ultrafiltration membrane by alkali metal chloride

    Institute of Scientific and Technical Information of China (English)

    张启修; 邱运仁

    2003-01-01

    The modified PVA-CA blend ultrafiltration membranes were prepared by phase inversion from the casting solutions consisting of polyvinyl alcohol(PVA), cellulose acetate(CA), acetic acid, alkali metal chloride and water. The effects of different concentration of alkali metal chloride on the properties of membranes were investigated. The results show that when the mass fraction of the salt in the casting solution is not greater than 1%, the property of rejection of the alkali metal salt modified ultrafiltration PVA-CA blend membrane has little change compared with that of the unmodified PVA-CA blend membrane, but the permeation flux is much greater than that of the unmodified membrane under the same operation condition. When the mass fraction of the salt is greater than 1.5%, the permeate flux increases much greater than that of the unmodified membrane, but the property of rejection of the modified ultrafiltration membrane decreases greatly. The results also show that the contact angle of the salt modified PVA-CA blend UF membrane decreases but the swelling in water increases with the increment of the mass fraction of alkali metal salts. Furthermore, the NaCl modified PVA-CA blend membrane has a slightly lower swelling and a little smaller contact angle of water than the KCl modified PVA-CA blend membrane does when the mass fraction of salts is the same.

  10. Low-polarity electrolytes on the base of crown ether complexes with alkali metal ions

    International Nuclear Information System (INIS)

    New low-polar electrolytes on the basis of 15-crown-5 complexes with alkali metal (lithium, sodium) ions in solvent characterized by low dielectrical permittivity: benzene, toluene, ethylene glycol dimethyl ether, tetrahydrofuran and methylene chloride, characterized by specific electrical permittivity equal to 10-5-10-2 Ohm-1·cm-1, are suggested and studied. 15 refs., 2 figs.,

  11. Unidirectional thermal expansion in KZnB3O6: role of alkali metals.

    Science.gov (United States)

    Lou, Yanfang; Li, Dandan; Li, Zhilin; Zhang, Han; Jin, Shifeng; Chen, Xiaolong

    2015-12-14

    The driving force of the unidirectional thermal expansion in KZnB3O6 has been studied experimentally and theoretically. Our results show that the low-energy vibrational modes of alkali metals play a crucial role in this unusual thermal behavior. PMID:26515521

  12. Long-range interactions between excited helium and alkali-metal atoms

    KAUST Repository

    Zhang, J.-Y.

    2012-12-03

    The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2 1,3S) and He(2 1,3P), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1–0.5%. For interactions with other alkali-metal atoms the uncertainty is 1–3% in the coefficient C5, 1–5% in the coefficient C6, and 1–10% in the coefficients C8 and C10. The dispersion coefficients Cn for the interaction of He(2 1,3S) and He(2 1,3P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3S) with the alkali-metal atoms in their first 2P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material.

  13. Mechanism of alkali metal insertion into TiO2 polymorphs

    Czech Academy of Sciences Publication Activity Database

    Zukalová, Markéta; Lásková, Barbora; Kavan, Ladislav

    Toulouse: Phantoms Foundation, 2015. s. 139-139. [TNT2015. Trends in Nanotechnology /16./. 07.09.2015-11.09.2015, Toulouse] R&D Projects: GA ČR GA13-07724S; GA ČR(CZ) GA15-06511S Institutional support: RVO:61388955 Keywords : TiO2 * alkali metal insertion Subject RIV: CG - Electrochemistry

  14. Alkali metal insertion into TiO2 polymorphs for battery applications

    Czech Academy of Sciences Publication Activity Database

    Zukalová, Markéta; Pitňa Lásková, Barbora; Kavan, Ladislav

    Dubai: EMN Dubai, 2016. s. 13-14. [EMN Dubai Meeting. Energy Materials Nanotechnology . 01.04.2016-04.04.2016, Dubai] R&D Projects: GA ČR GA15-06511S Institutional support: RVO:61388955 Keywords : TiO2 polymorphs * alkali metal insertion * LTO Subject RIV: CG - Electrochemistry

  15. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    Energy Technology Data Exchange (ETDEWEB)

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-08

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings.

  16. Infrared Photodissociation Spectroscopy of Metal Oxide Carbonyl Cations.

    Science.gov (United States)

    Brathwaite, Antonio D.; Duncan, Michael A.

    2013-06-01

    Mass selected metal oxide-carbonyl cations of the form MO_{m}(CO)_{n}^{+} are studied via infrared laser photodissociation spectroscopy, in the 600-2300cm^{1} region. Insight into the structure and bonding of these complexes is obtained from the number of infrared active bands, their relative intensities and their frequency positions. Density functional theory calculations are carried out in support of the experimental data. Insight into the bonding of CO ligands to metal oxides is obtained and the effect of oxidation on the carbonyl stretching frequency is revealed.

  17. Liquid metal cooled reactor - alkali metal thermoelectric space power system concept for multi megawatt applications

    International Nuclear Information System (INIS)

    A number of Strategic Defense Initiative missions require space power systems with lifetime on the order of 7 to 10 years and systems with reliabilities greater than 0.95. In addition, power source system mass must be as low as possible, consistent with existing and projected launch capabilities. For steady state power sources greater than tens of kilowatts, nuclear reactor systems would yield the lowest system mass. Among potential power conversion systems, Alkali Metal Thermoelectric (AMTEC) is highly attractive from a number of standpoints: it has the highest conversion efficiencies among the different types of static energy conversion systems at moderate operating temperatures that are reasonably high so that waste heat rejection can be carried out with relatively low system mass

  18. Rapid and efficient synthesis of alkali metal-C[sub 60] compounds in liquid ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Buffinger, D.R.; Ziebarth, R.P.; Stenger, V.A.; Recchia, C.; Pennington, C.H. (Ohio State Univ., Columbus, OH (United States))

    1993-10-06

    The reaction of stoichiometric amounts of alkali metals with C[sub 60] in liquid ammonia provides a rapid and quantitative route to M[sub x]C[sub 60] superconductors (M[sub x] = K[sub 3]/, Rb[sub 3]/, CsRb[sub 2], RbCs[sub 2], KRbCs). Annealing of the samples for 24-48 h at 375[degrees]C is required to obtain large superconducting fractions. [sup 13]C and [sup 87]Rb NMR line shapes are reported for Rb[sub 3]C[sub 60]. The [sup 13]C line shapes show the degree of rotational motion of the C[sub 60] ions varies considerably from sample to sample and is dependent on the method of preparation and subsequent heat treatment. A correlation between the degree of rotational motion and the superconducting fraction is noted and attributed to the amount of disorder in the sample. [sup 87]Rb NMR shows three peaks indicating that Rb[sub 3]C[sub 60] actually contains three different cation sites, rather than the two suggested by X-ray powder diffraction data. The third site is occupied by approximately 15% of the Rb ions in Rb[sub 3]C[sub 60] and is shown to be a subset of the tetrahedral sites in the cubic close-packed C[sub 60] lattice. Although the exact nature of the distortion required to produce the third site is unknown, it appears to be unrelated to the orientations of the C[sub 60] ions creating the site. 18 refs., 2 figs.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  1. Equilibrium electrode U(4)-U and redox U(4)-U(3) potentials in molten alkali metal chlorides medium

    International Nuclear Information System (INIS)

    Conditional standard electrode potentials of uranium are determined for diluted solutions of its tetrachloride in alkali metal chloride melts (LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl) when using U(4) ion activity coefficient values experimentally found by the tensimetric method. These potentials shift to the electronegative side at the temperature decrease and alkali cation radius increase rsub(Msup(+)) according to the empiric ratio E*U(4)-U= -3.06+6.87x10-4 T-(1.67-10-4T-0.44) 1/rsub(Msup(+)) +-0.01. The temperature dependences of formal conditional redox potentials of the U(4)-U(3) system for above melted chlorides are estimated. The E*U(4)-U(3) value also becomes more electronegative in the series LiCl, NaCl, NaCl-KCl, KCl, RbCl and CsCl. This alternation is satisfactorily described by the empiric expression E*U(4)-U(3)= -1.74+1.74x10-4T-(0.71x10-4T-0.20) 1rsub(Msup(+)) +-0.05. The calculated values Eu*(4)-U(3) are compared with those directly measured for the NaCl-KCl equimolar mixture and 3LiCl-2KCl eutectic mixture. A satisfactory confirmity has been observed

  2. A simple alkali-metal and noble gas ion source for SIMS equipments with mass separation of the primary ions

    International Nuclear Information System (INIS)

    An alkali-metal ion source working without a store of alkali-metals is described. The alkali-metal ions are produced by evaporation of alkali salts and ionization in a low-voltage arc discharge stabilized with a noble gas plasma or in the case of small alkali-metal ion currents on the base of the well known thermic ionization at a hot tungsten wire. The source is very simple in construction and produces a stable ion current of 0.3 μA for more than 100 h. It is possible to change the ion species in a short time. This source is applicable to all SIMS equipments using mass separation for primary ions. (author)

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

    OpenAIRE

    Sahin, Hasan; Peeters, Francois M.

    2013-01-01

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

  4. Electrohydrodynamic emission of positive and negative ions from alkali-metal halide melts

    International Nuclear Information System (INIS)

    The characteristics of electrohydrodynamic (EHD) emission of positive and negative ions from melts of alkali-metal metals are presented. The angular current density is 3-4 μA/sr with emission currents of 0.1-0.5 μA. The salt EHD sources which have been developed yield stable currents of K+, Rb+, Cs+, F-, Cl-, and I- ions for several tens of hours. 10 refs., 4 figs., 1 tab

  5. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    Science.gov (United States)

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space. PMID:27178415

  6. Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

    Institute of Scientific and Technical Information of China (English)

    由芳田; 黄世华; 时秋峰

    2010-01-01

    The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

  7. Molecular modeling of organic corrosion inhibitors: why bare metal cations are not appropriate models of oxidized metal surfaces and solvated metal cations.

    Science.gov (United States)

    Kokalj, Anton

    2014-01-01

    The applicability of various models of oxidized metal surfaces - bare metal cations, clusters of various size, and extended (periodic) slabs - that are used in the field of quantum-chemical modeling of corrosion inhibitors is examined and discussed. As representative model systems imidazole inhibitor, MgO surface, and solvated Mg(2+) ion are considered by means of density-functional-theory calculations. Although the results of cluster models are prone to cluster size and shape effects, the clusters of moderate size seem useful at least for qualitative purposes. In contrast, the bare metal cations are useless not only as models of oxidized surfaces but also as models of solvated cations, because they bind molecules several times stronger than the more appropriate models. In particular, bare Mg(2+) binds imidazole by 5.9 eV, while the slab model of MgO(001) by only 0.35 eV. Such binding is even stronger for 3+ cations, e.g., bare Al(3+) binds imidazole by 17.9 eV. The reasons for these fantastically strong binding energies are discussed and it is shown that the strong bonding is predominantly due to electron charge transfer from molecule to metal cation, which stems from differences between molecular and metal ionization potentials. PMID:25125117

  8. Dipicolinate complexes of main group metals with hydrazinium cation

    Indian Academy of Sciences (India)

    K Saravanan; S Govindarajan

    2002-02-01

    Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae (N2H5)2M(dip)2.H2O (where, M =Ca, Sr, Ba or Pb and = 0, 2, 4 and 3 respectively and dip = dipicolinate), N2H5Bi(dip)2.3H2O and (N2H5)3Bi(dip)3.4H2O have been prepared and characterized by physico-chemical techniques. The infrared spectra of the complexes reveal the presence of tridentate dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements show that the mono, di and trihydrazinium complexes behave as 1:1, 2:1 and 3:1 electrolytes respectively, in aqueous solution. Thermal decomposition studies show that these compounds lose water followed by endothermic decomposition of hydrazine to give respective metal hydrogendipicolinate intermediates, which further decompose exothermically to the final product of either metal carbonates (Ca, Sr, Ba and Pb) or metal oxycarbonates (Bi). The coordination numbers around the metal ions differ from compound to compound. The various coordination numbers exhibited by these metals are six (Ca), seven (Ba), eight (Sr) and nine (Pb and Bi). In all the complexes the above coordination number is attained by tridentate dipicolinate dianions and water molecules. The X-ray diffraction patterns of these compounds differ from one another suggesting that they are not isomorphous.

  9. Intra-zoned luminescence in alkali earth metal carbonates

    International Nuclear Information System (INIS)

    Full text: The fundamental plasma luminescence of wide band alkali halide crystals has been found out by Vaisburd et al. This broadband luminescence with very short duration of attenuation (∼10-12 s) arises at an irradiations of crystals with electronic beam powerful pulses of nanosecond duration. It is related to radiating 'hot' electrons and holes in a conductivity zone and in a valent zone, accordingly and in later time began to refer to as an intra-zoned luminescence. The data set on revealing features of display of an intra-zoned luminescence in different classes of crystals now proceeds. We investigated a fast luminescence at excitation with pulse electrons (3 nanoseconds) in crystals CaCO3, SrCO3, BaCO3 and MgCO3. In spectra all investigated carbonates it is possible to allocate two areas: area concerning high intensity of a fast luminescence (from 2 eV down 3 eV) and area of low intensity (is higher 4 eV) with slow recession at increase in photon energy. Thus it is typical, that in area concerning high intensity at rise in temperature from 80 up to 300 K a sample intensity of luminescence falls down, whereas in area is higher 5 eV with rise in temperature of a sample increase of intensity is observed. This broadband fast (is shorter than the time sanction of the equipment) should be connected a luminescence poorly dependent on temperature and a modular status of a sample with intra zoned transitions This luminescence reaches from 2 eV down to 7 eV but as for carbonates while is absent the reliable data on structure of a valent zone, division of an intra-zoned luminescence into electronic and hole components is not obviously possible on the basis of spectra of a fast luminescence. The nature of other luminescence processes arising at excitation with pulse electrons is discussed

  10. Development and testing of on-line analytical instrumentation for alkali and heavy metal release in pressurised conversion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V.; Oikari, R. [Tampere Univ. of Technology (Finland)

    1997-10-01

    The purpose of the project is to demonstrate in industrial conditions and further develop the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) developed at Tampere University of Technology (TUT). The demonstration takes place in joint measuring campaigns, where two other continuous alkali measurement methods, ELIF and surface ionisation, are being simultaneously demonstrated. A modification of PEARLS will also be developed for the continuous measurement of heavy metal concentrations. A market study of continuous measuring techniques for alkali and heavy metals is further part of the project. The method will be demonstrated in two pressurised fluidised bed combustion facilities. One of these is the 10 MW PCFB of Foster Wheeler Energia Oy in Karhula. The second one is yet to be decided. The first measuring campaign is scheduled for the spring of 1997 in Karhula. In 1996 the group at TUT participated in the performance of a market study regarding continuous measuring techniques for alkali and heavy metal concentrations. A draft report was submitted to and approved by the EC. Development work on PEARLS in 1996 has centered around the construction of a calibration device for alkali measurements. The device can be used by all three measuring techniques in the project to check readings against a known alkali concentration at controlled and known conditions. In 1996 PEARLS was applied for alkali measurement at several pressurised combustion installations of laboratory and industrial pilot scale

  11. 非水毛细管电泳分离碱金属、碱土金属和铵离子的机理研究%Investigation on Mechanism for Separation of Alkali, Alkaline Metal and Ammonium Cations in Nonaqueous Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    刘红霞; 宋鹃梅; 张书胜; MACKA Miroslav; HADDAD Paul R

    2004-01-01

    Capillary electrophoresis ( CE ) has rapidly gained great interests among researchers in many different fields. One of these areas is the separation of small ions such as inorganic cations, anions, and low Mr organic molecules However, as the separation of ions

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

    CERN Document Server

    Lutz, Jesse J

    2013-01-01

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

  13. Emission Channeling Studies of the Lattice Site of Oversized Alkali Atoms Implanted in Metals

    CERN Multimedia

    2002-01-01

    % IS340 \\\\ \\\\ As alkali atoms have the largest atomic radius of all elements, the determination of their lattice configuration following implantation into metals forms a critical test for the various models predicting the lattice site of implanted impurity atoms. The site determination of these large atoms will especially be a crucial check for the most recent model that relates the substitutional fraction of oversized elements to their solution enthalpy. Recent exploratory $^{213}$Fr and $^{221}$Fr $\\alpha$-emission channeling experiments at ISOLDE-CERN and hyperfine interaction measurements on Fr implanted in Fe gave an indication for anomalously large substitutional fractions. To investigate further the behaviour of Fr and other alkali atoms like Cs and Rb thoroughly, more on-line emission channeling experiments are needed. We propose a number of shifts for each element, where the temperature of the implanted metals will be varied between 50$^\\circ$ and 700$^\\circ$~K. Temperature dependent measurements wi...

  14. X-ray Compton scattering experiments for fluid alkali metals at high temperatures and pressures

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, K., E-mail: kazuhiro-matsuda@scphys.kyoto-u.ac.jp; Fukumaru, T.; Kimura, K.; Yao, M. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Tamura, K. [Graduate School of Engineering, Kyoto University, Kyoto 606-8502 (Japan); Katoh, M. [A.L.M.T. Corp., Iwasekoshi-Machi 2, Toyama 931-8543 (Japan); Kajihara, Y.; Inui, M. [Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

    2015-08-17

    We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

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

    International Nuclear Information System (INIS)

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

  16. An Aqueous Redox Flow Battery Based on Neutral Alkali Metal Ferri/ferrocyanide and Polysulfide Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiaoliang; Xia, Gordon; Kirby, Brent W.; Thomsen, Edwin C.; Li, Bin; Nie, Zimin; Graff, Gordon L.; Liu, Jun; Sprenkle, Vincent L.; Wang, Wei

    2015-11-13

    Aiming to explore low-cost redox flow battery systems, a novel iron-polysulfide (Fe/S) flow battery has been demonstrated in a laboratory cell. This system employs alkali metal ferri/ferrocyanide and alkali metal polysulfides as the redox electrolytes. When proper electrodes, such as pretreated graphite felts, are used, 78% energy efficiency and 99% columbic efficiency are achieved. The remarkable advantages of this system over current state-of-the-art redox flow batteries include: 1) less corrosive and relatively environmentally benign redox solutions used; 2) excellent energy and utilization efficiencies; 3) low cost for redox electrolytes and cell components. These attributes can lead to significantly reduced capital cost and make the Fe/S flow battery system a promising low-cost energy storage technology. The major drawbacks of the present cell design are relatively low power density and possible sulfur species crossover. Further work is underway to address these concerns.

  17. Equation of state for thermodynamic properties of pure and mixtures liquid alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Mousazadeh, M.H., E-mail: mmousazadeh@aeoi.org.ir [Department of Chemistry, Nuclear Science Research School, Nuclear Science and Technology Research Institute (NSTRI), End of North-Karegar Str., 11365-3486 Tehran (Iran, Islamic Republic of); Faramarzi, E. [Department of Physical Chemistry, School of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Maleki, Z. [Department of Chemistry, Nuclear Science Research School, Nuclear Science and Technology Research Institute (NSTRI), End of North-Karegar Str., 11365-3486 Tehran (Iran, Islamic Republic of)

    2010-11-20

    We developed an equation of state based on statistical-mechanical perturbation theory for pure and mixtures alkali metals. Thermodynamic properties were calculated by the equation of state, based on the perturbed-chain statistical associating fluid theory (PC-SAFT). The model uses two parameters for a monatomic system, segment size, {sigma}, and segment energy, {epsilon}. In this work, we calculate the saturation and compressed liquid density, heat capacity at constant pressure and constant volume, isobaric expansion coefficient, for which accurate experimental data exist in the literatures. Results on the density of binary and ternary alkali metal alloys of Cs-K, Na-K, Na-K-Cs, at temperatures from the freezing point up to several hundred degrees above the boiling point are presented. The calculated results are in good agreement with experimental data.

  18. X-ray Compton scattering experiments for fluid alkali metals at high temperatures and pressures

    International Nuclear Information System (INIS)

    We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article

  19. The 3-Dimensional q-Deformed Harmonic Oscillator and Magic Numbers of Alkali Metal Clusters

    CERN Document Server

    Bonatsos, Dennis; Raychev, P P; Roussev, R P; Terziev, P A; Bonatsos, Dennis

    1999-01-01

    Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3) > SOq(3) symmetry are compared to experimental data for alkali metal clusters, as well as to theoretical predictions of jellium models, Woods--Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. The 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry of systems of alkali metal clusters.

  20. Effect of heavy metal cations on the activity of cathepsin D (in vitro study) Effect of heavy metal cations on the activity of cathepsin D (in vitro study)

    OpenAIRE

    Alicja Karwowska; Radosław Łapiński; Marek Gacko; Ewa Grzegorczyk; Joanna Żurawska; Jan K. Karczewski

    2012-01-01

    We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.We studied the effect of heavy metal c...

  1. Alkali-doped metal-phthalocyanine and pentacene compounds

    NARCIS (Netherlands)

    Craciun, M.F.

    2006-01-01

    The ability to introduce charge carriers in organic molecular materials and control their concentration is of great relevance for both fundamental research and applications. In this thesis, it has been demonstrated that the electronic properties of Metal Phthalocyanines (MPc) and pentacene (PEN) mol

  2. Metal cations inserted in vanadium-oxide nanotubes

    International Nuclear Information System (INIS)

    Vanadium-oxide nanotubes (VO x-NTs) consist of nanosize cylinders of thin, easily bent vanadyl (VO x) wall chains, which are open at both ends. Surfactant molecules (e.g. C12H27N) can be easily trapped in the interior of the nanotube walls. The structure of as-synthesized VO x-NTs are observed to collapse to an amorphous vanadium oxide at temperatures greater than 250 deg, C. This happens, even under a protective atmosphere. This property makes the VO x-NTs unusable as a catalyst at temperatures between 400-500 deg, C, which is the temperature range where many applications would exist. In order to increase the thermal stability of VO x-NTs several exchange reactions have been used to modify the original nanotubes. In these reactions metallic cations (Cd2+, Co2+, Mn2+ or Zn2+) were introduced. It was observed that that the morphology of the nanotubes remained unchanged after the exchange reactions were performed. In order to characterize the exchanged VO x-NTs the following analytic techniques were used: scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared, particle-induced X-ray emission and Rutherford backscattering spectrometry. The results showed that the VO x-NTs exchanged with metallic cations have preserved their tubular morphology. However, it has not been possible to fully perform a 100% efficient exchange reaction

  3. Conductometric determination of dissociation constants of alkali metal monopyrocatechinborates in alcohols

    International Nuclear Information System (INIS)

    Dissociation constants of alkali metal monopyrocatechinborates of Me[(C6H4O2)B(OH)2]xnH2O (Me = Na+, Li+) composition are determined using conductometric method based on equivalent electric conductivity values, in methanol and ethanol at 25 deg C. Dissociation constants of weak electrolytes are calculated by the Fuoss-Kraus method. Conditions of Valden raw action are determined which connects concentrations with permittivity of medium

  4. Ab initio GW quasiparticle calculation of small alkali-metal clusters

    International Nuclear Information System (INIS)

    Quasiparticle energies of small alkali-metal clusters are evaluated from first principles by means of the GW approximation with the generalized plasmon-pole model. An all-electron mixed-basis approach, in which wave function is represented as a linear combination of both plane waves and atomic orbitals, is adopted in the calculation. Obtained quasiparticle energies (ionization potential and electron affinity) are in good agreement with experimental data

  5. Characterization of the conduction properties of alkali metal ion conducting solid electrolytes using thermoelectric measurements

    OpenAIRE

    Gautam, Devendraprakash

    2006-01-01

    Under certain circumstances the electronic conductivity of the solid electrolyte may play a pivotal role for the behaviour of a solid state galvanic cell. Quantitatively, the extent of the electronic conductivity is expressed by the electronic conduction parameters, a and a, that denote the alkali metal activities at which the n and p-type electronic conductivities, respectively, of the electrolyte are equal to its ionic conductivity. Previous findings demonstrated the existen...

  6. Effect of radiation trapping on the polarization of an optically pumped alkali-metal vapor

    International Nuclear Information System (INIS)

    Calculations are presented of the limitations imposed by radiation trapping on the electron spin polarization produced in an alkali-metal vapor by optical pumping in a large magnetic field. It is found that electron spin polarizations of 90% are possible with Na densities up to 1019 atoms/m3 and ground-level relaxation times of 150 μs in a large magnetic field using a cylindrical geometry of radius 7.5 x 10-3 m

  7. Alkali Metal Modification of Silica Gel-Based Stationary Phase in Gas Chromatography

    OpenAIRE

    Ashraf Yehia El-Naggar

    2013-01-01

    Modification of the precipitated silica gel was done by treatment with alkali metal (NaCl) before and after calcination. The silica surfaces before and after modification were confirmed by infrared spectroscopy in order to observe the strength and abundance of the acidic surface OH group bands which play an important role in the adsorption properties of polar and nonpolar solutes. The surface-modified silica gels were tested as GC solid stationary phases in terms of the separation efficiency ...

  8. Ab initio GW quasiparticle calculation of small alkali-metal clusters

    CERN Document Server

    Ishii, S; Louie, S G; Ohno, K

    2001-01-01

    Quasiparticle energies of small alkali-metal clusters are evaluated from first principles by means of the GW approximation with the generalized plasmon-pole model. An all-electron mixed-basis approach, in which wave function is represented as a linear combination of both plane waves and atomic orbitals, is adopted in the calculation. Obtained quasiparticle energies (ionization potential and electron affinity) are in good agreement with experimental data.

  9. Active-alkali metal promoted reductive desulfurization of dibenzothiophene and its hindered analogues

    OpenAIRE

    Pittalis, Mario; Azzena, Ugo Gavino; Carraro, Massimo; Pisano, Luisa

    2013-01-01

    Reductive desulfurisation of organic compounds is of importance both in organic synthesis and in industry. Benzo- and dibenzothiophenes are between the most abundant sulphur containing impurities in crude oils, and their desulfurization is a mandatory issue in the production of non polluting fuels. Following our interest in the development of efficient alkali metal-mediated synthetic procedures and alternative protocols for the chemical transformation of widespread environmental contaminants ...

  10. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  11. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  12. A hexagonal structure for alkali-metal doped poly (p-phenylene)

    Science.gov (United States)

    Murthy, N. S.; Baughman, R. H.; Shacklette, L. W.; Fark, H.; Fink, J.

    1991-05-01

    An hexagonal structure (space group p overline62m, a = 8.6 Å) is proposed for sodium-doped poly(p-phenylene), PPP. The diffraction pattern calculated using only one freely adjustable parameter (the distance between the alkali-metal column and the polymer backbone) is in good agreement with the observed electron diffraction patterns. A similar structure ( a = 9.2 Å) is also suggested by diffraction data for potassium-doped PPP. This hexagonal structure is analogous to that reported for sodium-doped poly(p-phenylene vinylene), lithium-doped polyacetylene, and sodium-doped polyacetylene. The three chain per column arrangement provides a fundamental structural motif which maximizes the coordination of the negatively charged carbon atoms with both the alkali metal ions and the hydrogens, and maximizes interchain, intercolumn, and hydrogen to alkali-metal separations. The size of the dopant-ion relative to the cross-sectional dimensions of the host polymer determines whether the dopant-ion columns are formed in triangular (three chain per column) or tetragonal (four chain per column) channels.

  13. Equation of state for solid rare gases and alkali metals under pressure

    Science.gov (United States)

    Bonnet, Pierre

    2016-07-01

    This investigation is based on an atomic equation of state which takes into account the excluded volume of the atom being considered. Study of solid rare gases allows following the packing factor of the solid in equilibrium with the gas at different temperatures and of the solid and the liquid in the case of solid-liquid equilibria. The application of a pressure to the solid up to 9800 MPa allows determining the decrease in atomic volume and thus the compressibility. Such a study leads to proposing a new expression through dividing the pressure derivative (as a function of the excluded volume) by the pressure. This new coefficient is a pressure-independent constant but varies with the atom considered. Multiplied by the initial atomic volume, this coefficient has a unique value for all the rare gases. Furthermore, this is also true for the series of alkali metals with however a lower value of the coefficient. The atomic configurations of the two series are very different with one free electron for the alkali metals but closed shells for the rare gases. The alkali metals are therefore more complex than the rare gases. It is worthwhile to note that study of the equilibrium has not required the use of the principles of thermodynamics.

  14. Interpretation of X-ray diffraction from liquid alkali metals

    International Nuclear Information System (INIS)

    It is known that, near freezing, the peaks in the liquid structure factors of Na and K reflect the ordering of a body-centred cubic lattice. Therefore, we have considered the modifications introduced into the electron distribution of a body-centred cubic, nearly-free electron, metal by destruction of the long-range order. Use of the Wannier representation, as has been pointed out by Matthai et al. leads naturally in a metal to bond charges at the centres of near-neighbour, next-near neighbour, etc. bonds. Because of the absence of long-range order in the nuclei of liquid Na and K, it is argued that only near-neighbour and perhaps next-near neighbour bond charges remain meaningful. Thus, whereas in crystalline Na and K, the totality of the bond charge distributions, including however many longer and longer bonds, adds up to an almost constant electron density of the valence electrons, in the liquid the local angularity of the electron density is significant. We find then that a model which can explain the observed reflections, which are characteristic of a face-centred-cubic lattice, can be built up by: (a) using local sp3 type bonding charges, with Pauling resonance invoked between occupied and unoccupied bonds; (b) assuming, once local electron co-ordination characteristic of such bonds is formed, Wigner-type lattice ordering can propagate the face-centred lattice over distances of 30 to 40 A. The differences to be expected between nearly-free electron metals and tight-binding metals in the liquid state are finally stressed. (author)

  15. An Overview on Metal Cations Extraction by Azocalixarenes

    Directory of Open Access Journals (Sweden)

    Hasalettin Deligöz

    2011-12-01

    Full Text Available In this overview, our main aim is to present the design, preparation, characterization, and extraction/sorption properties of chromogenic azocalix[4]arenes (substituted with different groups toward metal cations. Azocalixarenes, which contain a conjugated chromophore, i.e. azo (-N=N- group are synthesized in “one-pot” procedures in satisfactory yields. A wide variety of applications is expected by the functionalization of the side arms. Some of them are used to complex with metal ions. These macrocycles due to their bowl-shaped geometry are indeed used as hosts allowing ionic or organic guests to coordinate onto their cavity. The azocalixarene based ionophores are generally applied in various fields such as catalyst recovery, power plant, agriculture, metals finishing, microelectonics, biotechnology processes, rare earths speciation, and potable water purification. Besides these, they find applications in the area of selective ion extractions, receptors, optical devices, chemical sensor devices, the stationary phase for capillary chromatography, ion transport membranes, and luminescence probes etc. This survey is focused to provide overview an of the versatile nature of azocalix[n]arenes as highly efficient extractants for metal ions treated as pollutants.

  16. Gaussian-basis LDA and GGA calculations for alkali-metal equations of state

    International Nuclear Information System (INIS)

    Recently there has been renewed interest in implementations of density-functional theory for solids using various types of localized basis sets, including atom-centered Gaussian-type functions. While such methods are clearly well adapted to most insulating and semiconducting systems, one might expect them to give a less-than-optimal description of metals relative to plane-wave-type methods. Nevertheless, several successful applications of local-basis methods to metals have recently been reported. Here, we report an application of our Gaussian linear combination of atomic orbitals (LCAO) code to some extremely free-electron-like metals, namely, the alkali metals Li, Na, and K. In agreement with other calculations (both local and plane wave) we find that the local-density approximation (LDA) lattice constants are relatively poor (∼-3% from experiment for the alkali metals versus ±1% for many other solids) and that the LDA bulk moduli are ∼30% too high. We find that the Perdew-Burke-Enzerhof (PBE) version of the generalized-gradient approximation (GGA) corrects most of this error, in agreement with earlier calculations using similar GGA functionals. The Becke-Lee-Yang-Parr GGA functional gives similar results for the alkali-metal equations of state but is found to overcorrect the errors of the LDA for the cohesive energies, for which the PBE functional is in better agreement with experiment. Our results indicate that the Gaussian-LCAO method should be able to give accurate results for nearly any crystalline solid, since it succeeds even where it would be expected to have the most difficulty. copyright 1998 The American Physical Society

  17. Theory of alkali-metal-induced reconstructions of fcc(100) surfaces

    DEFF Research Database (Denmark)

    Christensen, Ole Bøssing; Jacobsen, Karsten Wedel

    1992-01-01

    Calculations of missing-row reconstruction energies of the fcc(100) surfaces of the metals Al, Ni, Pd, Pt, Cu, Ag, and Au have been performed with the effective-medium theory with and without the presence of a potassium overlayer. It is shown that the tendency to reconstruct in the presence of...... adsorbed K is largest for Ag. This is in accordance with recent experiments indicating a potassium-induced missing-row reconstruction for Ag, but not for other metals. The tendency is shown to be related to the relatively low bulk modulus of silver. Differences from the well-known alkali...

  18. ELECTROHYDRAULIC LEACHING OF ALKALI METALS FROM ZINNWALDITE MICA

    Czech Academy of Sciences Publication Activity Database

    Faltus, M.; Babický, Václav; Botula, J.; Hong Vu, N.; Člupek, Martin

    Bratislava: Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava (Slovakia); Society for Plasma Research and Applications in cooperation with Library and Publishing Centre CU, Bratislava, Slovakia, 2015 - (Papp, P.; Országh, J.; Moravský, L.; Ribar, A.; Matejčík, Š.), s. 234-239 ISBN 978-80-8147-027-1. [Symposium on Application of Plasma Processes COST TD1208 Workshop on Application of Gaseous Plasma with Liquids: SAPP XX /20./. Tatranská Lomnica (SK), 17.01.2015-22.01.2015] R&D Projects: GA MŠk(CZ) LD14080 Grant ostatní: European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : electrical discharge in liquid * leaching of metals Subject RIV: BL - Plasma and Gas Discharge Physics http://is.muni.cz/repo/1219429/SAPP_XX_2015.pdf

  19. Modulation of the work function of fullerenes C60 and C70 by alkali-metal adsorption: A theoretical study

    International Nuclear Information System (INIS)

    The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C60 and C70 was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C60 and C70 decrease distinctly and vary linearly with the electronegativity of the alkali metal elements, and the positions where the alkali atoms are adsorbed considerably influence the work functions. On the contrary, a vacancy defect elevates the work functions of the fullerenes C60 and C70. The variation in the work functions rests with variation in Fermi level (which are attributed to charge transfer) and variation in vacuum levels (which are attributed to the induced dipole moments). Moreover, alkali-metal adsorption can also improve the electric conductivity of a fullerene mixture of C60 and C70.

  20. Ab initio study of the transition-metal carbene cations

    Institute of Scientific and Technical Information of China (English)

    李吉海; 冯大诚; 冯圣玉

    1999-01-01

    The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH2+ were investigated by ab initio molecular orbital theory (HF/LANL2DZ). All of MCH2+ are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2px orbital of C and 4px, 3dxz, orbitals of M+ that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.

  1. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes;

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...... metal atom (M2) plus two to five (BH4)− groups, i.e., M1M2(BH4)2–5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with...

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

    Science.gov (United States)

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

    2000-12-01

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

  3. Alkali and heavy metal emissions of the PCFB-process; Alkalipaeaestoet PCFB-prosessissa

    Energy Technology Data Exchange (ETDEWEB)

    Kuivalainen, R.; Eriksson, T.; Lehtonen, P. [Foster Wheeler Energia Oy, Karhula (Finland)

    1996-12-01

    Pressurized Circulating Fluidized Bed (PCFB) combustion technology has been developed in Karhula R and D Center since 1986. As a part of the development, 10 MW PCFB Test Facility was built in 1989. The Test Facility has been used for performance testing with different coal types through the years 1990-1995 in order to gain data for design and commercialization of the high-efficiency low-emission PCFB combustion technology. The project Y44 `Alkali and heavy metal emissions of the PCFB-process` was part of national LIEKKI 2 research program. The main object of the project was to measure vapor phase Na and K concentrations in the PCFB flue gas after hot gas filter and investigate the effects of process conditions and sorbents on alkali release. The measurements were performed using plasma assisted method by TUT Laboratory of Plasma Technology and wet absorption method of VTT Energy. The measured Na concentrations were below 30 ppb(w) in all measured data points. The results of K were below 10 ppb(w). The accuracies of the both methods are about + 50 % at this concentration range. The scatter of the data covers the effects of different process variables on the alkali emission. The measured emissions are at the same order of magnitude as the guideline emission limits estimated by gas turbine manufacturers. The measurements and development of the analyses methods are planned to be continued during PCFB test runs in spring 1996 for example within Joule II research program. (author)

  4. Solubility of some phenolic compounds in aqueous alkali metal nitrate solutions from (293.15 to 318.15) K

    International Nuclear Information System (INIS)

    This paper is continuation of the study concerning the solubility-temperature dependence data for some phenolic compounds (PhC), contained in olive mill wastewater (OMWW), in two nitrate salts (KNO3 and NaNO3) aqueous solutions. The solubilities of PhC were determined in the temperature ranging from (293.15 to 318.15) K. It has been observed that the solubility, in aqueous nitrate solutions, increases with increasing temperature. Results showed that alkali metal nitrate has a salting-out effect on the solubility of PhC. The effect of the anion of the electrolyte on the solubility of PhC is observed by comparing these results with values reported in the previous papers for the effect of LiCl, NaCl and KCl. For each cation, the solubilites of the phenolic compounds are higher with nitrate anion than with chloride anion. Results were interpreted in terms of the salt hydration shells and the ability of the solute to form hydrogen-bond with water. The solubility data were accurately correlated by a semi empirical equation. The standard molar Gibbs free energies of transfer of PhC (ΔtrG0) from pure water to aqueous solutions of the nitrate salts have been calculated from the solubility data. The decrease in solubility is correlated to the positive ΔtrG0 value which is mainly of enthalpic origin

  5. Near-infrared luminescence enhancing by introducing alkali metal ions in Sr2CeO4:Yb3+

    International Nuclear Information System (INIS)

    NIR luminescence phosphors Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) were synthesized by conventional solid-state method in the present paper. The prepared phosphors are characterized by XRD and fluorescence spectrometer. Under UV light excitation, the NIR emission intensity of Yb3+:2F5/2→2F7/2 around 1 μm of Sr2CeO4:Yb3+ is strengthened significantly by introducing appropriate alkali metal cations dopants (Li+, Na+, K+) into the crystalline lattice. The relevant mechanisms have been discussed in detail. The peculiar optical properties make Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) promising for potential application in the high efficiency silicon-based solar cells. -- Highlights: • Pure orthorhombic Sr2CeO4:Yb3+, M+ (M+=Li+, Na+, K+) were successfully synthesized. • The structural and photoluminescence of these samples were characterized by XRD and fluorescence spectrometer. • The effect of Li+/Na+/K+ on the properties of samples had been researched and the relevant mechanisms have been discussed in detail. • These NIR materials could have potential application in the high efficiency silicon-based solar cells

  6. The influence of chlorine on the fate and activity of alkali metals during the gasification of wood

    Energy Technology Data Exchange (ETDEWEB)

    Struis, R.; Scala, C. von; Schuler, A.; Stucki, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Chlorine clearly inhibits the CO{sub 2}-gasification reaction of charcoal at 800{sup o}C. From this and other observations the picture emerges that the reduction in the gasification reactivity of the charcoal is intimately related to the deactivation of the catalytically active alkali metals residing in the wood due to the formation of the chloride salt. It is argued that the heavy metal chlorides will likely transfer the chlorine to the indigenous alkali metals during the pyrolysis stage of the wood. The fate of the thus formed alkali metal chlorides can then be either their removal from the sample (evaporation), or, when present at the gasification stage, re-activation (i.e., de-chlorination) under our gasification conditions. (author) 3 figs., 4 refs.

  7. Intercalation of heavy alkali metals (K, Rb and Cs) in the bundles of single wall nanotubes

    Science.gov (United States)

    Duclaux, L.; Méténier, K.; Lauginie, P.; Salvetat, J. P.; Bonnamy, S.; Beguin, F.

    2000-11-01

    The electric-arc discharge carbon deposits (collaret) containing Single Wall Carbon Nanotubes (SWNTs) were heat treated at 1600 °C during 2 days under N2 flow in order to eliminate the Ni catalyst by sublimation, without modifications of the SWNTs ropes. Sorting this deposit by gravity enabled to obtain in the coarsest particles higher amount of SWNTs ropes than in other particle sizes. The coarser particles of the carbon deposits were reacted with the alkali metals vapor giving intercalated samples with a MC8 composition. The intercalation led to an expansion of the 2D lattice of the SWNTs so that the alkali metals were intercalated in between the tubes within the bundles. Disordered lattices were observed after intercalation of Rb and Cs. The simulations of the X-ray diffractograms of SWNTs reacted with K, gave the best fit for three K ions occupying the inter-tubes triangular cavities. The investigations by EPR, and 13C NMR, showed that doped carbon deposits are metallic.

  8. Thermodynamics and structure of liquid alkali metals from the charged-hard-sphere reference fluid

    International Nuclear Information System (INIS)

    The evaluation of thermodynamic properties of liquid alkali metals is re-examined in the approach based on the Gibbs-Bogoliubov inequality and using the fluid of charged hard spheres in the mean spherical approximation as reference system, with a view to achieving consistency with the liquid structure factor. The perturbative variational calculation of the Helmholtz free energy is based on an ab initio and highly reliable nonlocal pseudopotential. Only limited improvement is found in the calculated thermodynamic functions, even when full advantage is taken of the two variational parameters inherent in this approach. The role of thermodynamic self-consistency between the equations of state of the reference fluid derived from the routes of the internal energy and of the virial theorem is then discussed, using previous results by Hoye and Stell. An approximate evaluation of the corresponding contribution to the free energy of liquid alkali metals yields appreciable improvements in both the thermodynamic functions and the liquid structure factor. It thus appears that an accurate treatment of thermodynamic self-consistency in the charged-hard-sphere system may help to resolve some of the difficulties that are commonly met in the evaluation of thermodynamic and structural properties of liquid metals. (author). 55 refs, 4 figs, 4 tabs

  9. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

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

    OpenAIRE

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

    1992-01-01

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

  11. Van der Waals coefficients for alkali metal clusters and their size dependence

    Indian Academy of Sciences (India)

    Arup Banerjee; Manoj K Harbola

    2006-02-01

    In this paper we employ the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waals coefficients 6 and 8 of alkali metal clusters of various sizes including very large clusters. Such calculations become computationally very demanding in the orbital-based Kohn-Sham formalism, but are quite simple in the hydrodynamic approach. We show that for interactions between the clusters of the same sizes, 6 and 8 scale as the sixth and the eighth power of the cluster radius, respectively, and approach their classically predicted values for the large size clusters.

  12. Conductimetric determination of dissociation constants of alkali metal (bis)pyrocatechol borates in alcohols

    International Nuclear Information System (INIS)

    Dissociation constants of dipyrocatechinborates of the alkali metals of the Me[C6H4O2)2B] composition, where M - Na, K, Rb, Cs in the methanol and ethanol medium at 25 deg C, are determined through conductometric method on the basis of values of equiva lent electroconductivities. The dissociation constants of low power electrolytes are calculated through the Fuoss-Kraus method. The performance conditions of the Valden rule, binding the substances concentrations with dielectric permittivity of the medium, are identified

  13. Cycle analysis of an alkali metal thermo-electric converter for small capillary type

    International Nuclear Information System (INIS)

    This paper describes the design of a small size Alkali Metal Thermal to Electric Converter (AMTEC) which employs a capillary structure for recirculating sodium working fluid. The cycle is based on the simple and small capillary type β-alumina and wick tube element. The proposed cell consists of the 37 conversion elements with capillary tube of 50μm in diameter and the sealed cylindrical vessel of 22mm in outer diameter. Results on the cycle analysis of sodium flow and heat transfer in the cell showed that the expected power output was 4.65 W and the conversion efficiency was 19% for the source temperature of 900 K

  14. A study of the chemistry of alkali metals in the upper atmosphere

    Science.gov (United States)

    Silver, J. A.; Kolb, C. E.

    1985-01-01

    The reactions of metallic species introduced into the atmosphere by meteor ablation may play a significant role in mesospheric and stratospheric chemistry. During this second year of a three year program to investigate these phenomena, we have completed measurements for the reactions of atomic sodium with ozone, and of NaO with ozone. Preliminary measurements of the rate constant for the reaction of NaO2 + HCl have been done, as well as an initial photodissociation cross section determination for NaCl at 193 nm. We have also begun to investigate the means by which neutral gas phase alkali species may be removed from the mesosphere and stratosphere.

  15. Alkali Metal Control over N–N Cleavage in Iron Complexes

    OpenAIRE

    Grubel, Katarzyna; Brennessel, William W.; Mercado, Brandon Q.; Holland, Patrick L.

    2014-01-01

    Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber–Bosch process, there is still ambiguity about the number of Fe atoms involved during the N–N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe–N...

  16. Evaluation of Ce3+ and alkali metal ions Co-doped LiSrAlF6 crystalline scintillators

    International Nuclear Information System (INIS)

    High scintillation efficiency of Eu-doped LiSrAlF6 (LiSAF) and LiCaAlF6 (LiCAF) codoped with alkali metal ions has been reported in our recent studies. Thus in this paper, we demonstrated the scintillation properties of 1% Ce-doped LiSAF crystals with 1% alkali metal ions co-doping to increase the light yield and understand the scintillation mechanism. The crystals showed intense emission band corresponding to the 5d-4f transition of Ce3+, and their light yields under thermal neutron excitation were higher than that of the Ce only doped crystal. Especially, the light yield of Ce–Na co-doped crystal exceeded about two times that of Ce only doped one. -- Highlights: ► Ce-doped and alkali metal co-doped LiSAF crystals were grown by μ-PD method. ► Alkali metal co-doped crystals showed higher light yield than Ce only doped crystal. ► Decay time of alkali metal co-doped LiSAF were longer than that of Ce only doped one

  17. Effect of heavy metal cations on the activity of cathepsin D (in vitro study Effect of heavy metal cations on the activity of cathepsin D (in vitro study

    Directory of Open Access Journals (Sweden)

    Alicja Karwowska

    2012-10-01

    Full Text Available We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.We studied the effect of heavy metal cations: Fe 2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ on the activity of
    cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin
    was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg2+ cations
    inhibit the activity of cathepsin D. Cations Hg2+ damage lysosomes and release cathepsin D from these organelles.

  18. Metal cation/anion adsorption on calcium carbonate: Implications to metal ion concentrations in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, J.M.; Cowan, C.E.; Resch, C.T.

    1990-05-01

    This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with surface Ca and anions exchange with surface CO{sub 3}. A general surface-exchange model was developed to account for the effects of Ca and CO{sub 3} concentrations, pH, and calcite surface area on cation and anion sorption onto calcite. The model was applied to recently developed experimental sorption data of Zn and SeO{sub 3} on specimen calcite in equilibrium CaCO{sub 3}(aq) suspensions. The surface-exchange model was able to describe the effects of pH on both cation and anion sorption, and provided good predictions of the effects of variable CO{sub 2}(g) pressure on Zn sorption and of PO{sub 4} on SeO{sub 3} sorption. The surface-exchange model, combined with sorption constants for other phases, was used to calculate Cd sorption to a hypothetical aquifer material containing a mixture of sorbents. The sorbent concentrations were fixed to those expected in groundwater zones. The multi-sorbent calculation documented the importance of calcite as a sorbent for metallic ions in groundwater.93 refs., 18 figs., 5 tabs.

  19. Structural changes of polyacids initiated by their neutralization with various alkali metal hydroxides. Diffusion studies in poly(acrylic acid)s.

    Science.gov (United States)

    Masiak, Michal; Hyk, Wojciech; Stojek, Zbigniew; Ciszkowska, Malgorzata

    2007-09-27

    The changes in the three-dimensional structure of the poly(acrylic acid), PAA, induced by incorporation of various alkali-metal counterions have been evaluated by studying diffusion of an uncharged probe (1,1'-ferrocenedimethanol) in the polymeric media. The studies are supported by the measurements of conductivity and viscosity of the polymeric media. Solutions of linear PAA of four different sizes (molecular weights: 450,000, 750,000, 1,250,000, 4,000,000) were neutralized with hydroxides of alkali metals of group 1 of the periodic table (Li, Na, K, Rb, Cs) to the desired neutralization degree. The transport properties of the obtained polyacrylates were monitored by measuring the changes in the probe diffusion coefficient during the titration of the polyacids. The probe diffusivity was determined from the steady-state current of the probe voltammetric oxidation at disk microelectrodes. Diffusivity of the probe increases with the increase in the degree of neutralization and with the increase in viscosity. It reaches the maximum value at about 60-80% of the polyacid neutralization. The way the probe diffusion coefficients change is similar in all polyacid solutions and gels. The increase in the size of a metal cation causes, in general, an enhancement in the transport of probe molecules. The biggest differences in the probe diffusivities are between lithium and cesium polyacrylates. The differences between the results obtained for cesium and rubidium are not statistically significant due to lack of good precision of the voltammetric measurements. The measurements of the electric conductivity of polyacrylates and the theoretical predictions supplemented the picture of electrostatic interactions between the polyanionic chains and the metal cations of increasing size. In all instances of the PAAs, the viscosity of the solutions rapidly increases in the 0-60% range of neutralization and then becomes constant in the 60-100% region. With the exception of the shortest

  20. The effects of correlation, relativity, exchange, channels coupling and polarization in scattering of electrons by alkali-metal atoms and alkali-like ions

    International Nuclear Information System (INIS)

    The present review briefly presents the growing experimental as well as theoretical interest in recent years in the effects of correlation, relativity, exchange, channels coupling and polarization on the high precision scattering of electron by alkali-metal atoms and alkali-like ions. Many high precision experiments have been performed which need very high accurate theoretical prediction for correct interpretation and identification of different physical effects involved. Several sophisticated theoretical techniques have been developed for inclusion of the above mentioned effects which play an extremely important role in order to obtain results of high accuracy for understanding experimental observation of high precision. At present, we do not have a comprehensive and practical atomic scattering theory which accounts for all these effects on an equal footing. Future challenges and directions, in reliable electron-atom scattering calculations, have been discussed and suggested. (author). 136 refs, 16 figs

  1. New bonding configuration on Si(111) and Ge(111) surfaces induced by the adsorption of alkali metals

    DEFF Research Database (Denmark)

    Lottermoser, L.; Landemark, E.; Smilgies, D.M.; Nielsen, M.; Feidenhans'l, R. Falkenberg; Johnson, R.L.; Gierer, M.; Seitsonen, A.P.; Kleine, H.; Bludau, H.; Over, H.; Kim, S.K.; Jona, F.

    1998-01-01

    The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily f...... from the substrate reconstruction and shows a new bonding configuration consisting of consecutive fivefold and sixfold Si (Ge) rings in 〈11̅ 0〉 projection separated by channels containing the alkali metal atoms. © 1998 The American Physical Society......The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily...

  2. Alkali metal carbon dioxide electrochemical system for energy storage and/or conversion of carbon dioxide to oxygen

    Science.gov (United States)

    Hagedorn, Norman H. (Inventor)

    1993-01-01

    An alkali metal, such as lithium, is the anodic reactant; carbon dioxide or a mixture of carbon dioxide and carbon monoxide is the cathodic reactant; and carbonate of the alkali metal is the electrolyte in an electrochemical cell for the storage and delivery of electrical energy. Additionally, alkali metal-carbon dioxide battery systems include a plurality of such electrochemical cells. Gold is a preferred catalyst for reducing the carbon dioxide at the cathode. The fuel cell of the invention produces electrochemical energy through the use of an anodic reactant which is extremely energetic and light, and a cathodic reactant which can be extracted from its environment and therefore exacts no transportation penalty. The invention is, therefore, especially useful in extraterrestrial environments.

  3. A numerical study of spin-dependent organization of alkali-metal atomic clusters using density-functional method

    International Nuclear Information System (INIS)

    We calculate the different geometric isomers of spin clusters composed of a small number of alkali-metal atoms using the UB3LYP density-functional method. The electron density distribution of clusters changes according to the value of total spin. Steric structures as well as planar structures arise when the number of atoms increases. The lowest spin state is the most stable and Lin, Nan, Kn, Rbn, and Csn with n = 2–8 can be formed in higher spin states. In the highest spin state, the preparation of clusters depends on the kind and the number of constituent atoms. The interaction energy between alkali-metal atoms and rare-gas atoms is smaller than the binding energy of spin clusters. Consequently, it is possible to self-organize the alkali-metal-atom clusters on a non-wetting substrate coated with rare-gas atoms.

  4. Higher-order Cn dispersion coefficients for the alkali-metal atoms

    International Nuclear Information System (INIS)

    The van der Waals coefficients, from C11 through to C16 resulting from second-, third-, and fourth-order perturbation theory are estimated for the alkali-metal (Li, Na, K, and Rb) atoms. The dispersion coefficients are also computed for all possible combinations of the alkali-metal atoms and hydrogen. The parameters are determined from sum rules after diagonalizing a semiempirical fixed core Hamiltonian in a large basis. Comparisons of the radial dependence of the Cn/rn potentials give guidance as to the radial regions in which the various higher-order terms can be neglected. It is seen that including terms up to C10/r10 results in a dispersion interaction that is accurate to better than 1% whenever the inter-nuclear spacing is larger than 20a0. This level of accuracy is mainly achieved due to the fortuitous cancellation between the repulsive (C11,C13,C15) and attractive (C12,C14,C16) dispersion forces

  5. 3718-F Alkali Metal Treatment and Storage Facility Closure Plan. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    None

    1992-11-01

    The Hanford Site, located northwest of the city of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials, as well as for activities associated with nuclear energy development. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. The 3718-F Alkali Metal Treatment and Storage Facility (3718-F Facility), located in the 300 Area, was used to store and treat alkali metal wastes. Therefore, it is subject to the regulatory requirements for the storage and treatment of dangerous wastes. Closure will be conducted pursuant to the requirements of the Washington Administrative Code (WAC) 173-303-610 (Ecology 1989) and 40 CFR 270.1. Closure also will satisfy the thermal treatment facility closure requirements of 40 CFR 265.381. This closure plan presents a description of the 3718-F Facility, the history of wastes managed, and the approach that will be followed to close the facility. Only hazardous constituents derived from 3718-F Facility operations will be addressed.

  6. Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

    Directory of Open Access Journals (Sweden)

    Matthias Leven

    2013-01-01

    Full Text Available Four catalysts based on new amides of chiral 1,2-diamines and 2-sulfobenzoic acid have been developed. The alkali-metal salts of these betaine-like amides are able to form imines with enones, which are activated by Lewis acid interaction for nucleophilic attack by 4-hydroxycoumarin. The addition of 4-hydroxycoumarin to enones gives ee’s up to 83% and almost quantitative yields in many cases. This novel type of catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components.

  7. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    International Nuclear Information System (INIS)

    The calculations in a majority of previous works for the fulleride (AqC60) crystals were performed within the framework of the rigid-lattice model, neglecting the distortion relaxation of the host fullerene (C60) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distoration field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. This paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of statistic concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method. In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the statistic inherent reorientation and/or displacements of the solvent molecules from the average-lattice sites as well as on the lattice parameter a of the elastically-anysotropic cubic C60 crystal are taken into account

  8. Macroscopic and bulk-controlled elastic modes in an interaction of interstitial alcali metal cations within a face-centered cubic crystalline fullerine

    Energy Technology Data Exchange (ETDEWEB)

    Tatarenko, V.A.; Tsysman, C.L.; Oltarzhevskaya, Y.T. [Institute for Metal Physics, Kiev (Ukraine)

    1994-12-31

    The calculations in a majority of previous works for the fulleride (AqC{sub 60}) crystals were performed within the framework of the rigid-lattice model, neglecting the distoration relaxation of the host fullerene (C{sub 60}) crystal caused by the interstitial alkali-metal (A) cations. However, an each cation is a source of a static distoration field, and the resulting field is a superposition of such fields generated by all cations. This is a reason why the host-crystal distortions depend on the A-cations configurations, i.e. on a type of a spatial bulk distribution of interstitial cations. This paper seeks to find a functional relation between the amplitudes of the doping-induced structure-distortion waves and of statistic concentration ones. A semiphenomenological model is constructed here within the scope of statistical-thermodynamic treatment and using the lattice-statistics simulation method. In this model the effects due to the presence of q solute A cations over available interstices (per unit cell) on the statistic inherent reorientation and/or displacements of the solvent molecules from the average-lattice sites as well as on the lattice parameter a of the elastically-anysotropic cubic C{sub 60} crystal are taken into account.

  9. Ab initio interaction potentials and scattering lengths for ultracold mixtures of metastable helium and alkali-metal atoms

    Science.gov (United States)

    Kedziera, Dariusz; Mentel, Łukasz; Żuchowski, Piotr S.; Knoop, Steven

    2015-06-01

    We have obtained accurate ab initio +4Σ quartet potentials for the diatomic metastable triplet helium+alkali-metal (Li, Na, K, Rb) systems, using all-electron restricted open-shell coupled cluster singles and doubles with noniterative triples corrections CCSD(T) calculations and accurate calculations of the long-range C6 coefficients. These potentials provide accurate ab initio quartet scattering lengths, which for these many-electron systems is possible, because of the small reduced masses and shallow potentials that result in a small amount of bound states. Our results are relevant for ultracold metastable triplet helium+alkali-metal mixture experiments.

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

    CERN Document Server

    Soldán, Pavel; Hutson, Jeremy M

    2009-01-01

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

  11. Alkali metal ion-proton exchange equilibria and water sorption studies on nafon 117 membrane and dowex 50 W exchange resins: effect of long storage or aging

    International Nuclear Information System (INIS)

    Alkali metal ion -H+ exchanges on Nafion 117 membrane treated differently, Dowex 50 W x 4 and Dowex 50 W x 8 resins have been studied at a total ionic strength of 0.1 mol dm-3. The water sorption isotherms of these exchangers in different ionic forms generated over the entire range of water activity, have been analysed by the D'Arcy and Watt equation (DWE). Water sorption studies have shown that the physical structure of the exchangers have changed due to long -storage or aging, resulting in poorer water sorption and even formation of pores in the case of Dowex 50 W x 8 resin. As a result, the counter ions in the exchangers are not hydrated and the water is present in a free form, albeit structured, in the resin phase. The selectivity sequence for the alkali metal ions with reference to the H+ (Li+++) for the exchangers used in the present study is in accordance with that reported in the literature for the ionomers having sulphonic acid as the functional group. In view of the absence of hydration of the cations in the resin phase, the driving force for the selectivity of the cation, namely, the net gain in entropy, is expected to come from the loss of structured water during the exchange process. Pre treating the Nafion 117 membrane with boiling acid solution activates the clustered region of the membrane in the H+ form, while pretreatment with boiling water expands the non-ionic domain (the region connecting the clusters). These modifications influence the state of water present in the Nafion 117 membrane and the ion exchange equilibria. As a result of long storage or aging, the ion exchangers lose their elasticity or swelling characteristics. The results obtained in the present study indicate that in aged materials, the ionogenic groups are existing as isolated ion -pairs rather than in a clustered morphology. (author)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  14. Mechanism of selective ion flotation. 1. Selective flotation of transition metal cations

    International Nuclear Information System (INIS)

    An experimental investigation is presented of the batch ion flotation of the transition metal cations Cr3+, Fe3+, Mn2+, Co2+, Zn2+, Ag+, Cd2+, and In3+ from acidic aqueous solutions with sodium dodecylsulfonate and sodium dodecylbenzenesulfonate as anionic surfactants. The selectivity sequences Mn2+ 2+ 2+ 3+ 3+ and Ag+ 2+ 3+ are established, both from data for single and multi-ion metal cations solutions, where sublate was not formed in the bulk solution. Good agreement between the selectivity sequences and the values of ionic potential of metal cations was found. An experimental investigation was also performed on the solubility of sublates. The sublates solubility values are discussed in terms of ionic potentials of metal cations as well as of the surfactant size

  15. Effect of heavy metal cations on the activity of cathepsin D (in vitro study).

    Science.gov (United States)

    Karwowska, Alicja; Łapiński, Radosław; Gacko, Marek; Grzegorczyk, Ewa; Żurawska, Joanna; Karczewski, Jan K

    2012-01-01

    We studied the effect of heavy metal cations: Fe²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ on the activity of cathepsin D in human aorta homogenate and blood serum. The concentration of cations was 1 mmol/l. Hemoglobin was the cathepsin D substrate. The activity of cathepsin D was determined at pH 3.5. Only Hg²⁺ cations inhibit the activity of cathepsin D. Cations Hg²⁺ damage lysosomes and release cathepsin D from these organelles. PMID:23042275

  16. Disposal of heavy metal cations in aqueous media by adsorption on coal to Ghazni

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2008-03-01

    Full Text Available  Adsorption of Pb and Cu cations and their mixture on the surface of modified and non-modified anti-gas coal trough different time intervals have been studied. The maximum adsorption capacity of coal relative to each cations have been determined. Absence  of concurrence between cations of Pb and Cu during adsorption from mixture is explained by difference of  types of their interaction with coal surface. The high effectiveness and perspectivities of application of anti-gas coal for neutralization of heavy metal cations in aqueous solution was shown.

  17. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

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

    CERN Document Server

    Derevianko, Andrei; Babb, James F

    2009-01-01

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

  19. Momentum densities and Compton profiles of alkali-metal atoms

    Indian Academy of Sciences (India)

    Pranab Sarkar; Anupam Sarkar; S N Roy; B Talukdar

    2003-03-01

    It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from 3Li to 37Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton profile are found to be in good agreement with the results of more detailed configuration-interaction calculations for the atom 3Li. Similar results for 11Na, 19K and 37Rb are compared with the corresponding Hartree–Fock–Roothaan values only, for want of data from other realistic calculations.

  20. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, A.B.; Kudyakov, V.Ya.; Smirnov, M.V.; Moskalenko, N.I. (AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii)

    1984-08-01

    The coefficient of HfCl/sub 4/ and ZrCl/sub 4/ separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl/sub 4/+HfCl/sub 4/). HfCl/sub 4/ and ZrCl/sub 4/ are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl.

  1. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    International Nuclear Information System (INIS)

    The coefficient of HfCl4 and ZrCl4 separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl4+HfCl4). HfCl4 and ZrCl4 are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl

  2. Secondary transformation mechanism of paramagnetic centers in irradiated alkali metal perchlorates

    International Nuclear Information System (INIS)

    The EPR method has been used to study thermal transformations of paramagnetic centres (PC) in X-ray irradiated potassium, rubidium and cesium perchlorates. Experimental data make it possible to suppose that diffusion coefficient of O- ion a rather high and this ion is freely diffused already at 262 K. Colliding with [MeClO4]+ centres it is transformed in a molecule of oxygen. Another part of O- is transformed in stable ozonide-ion at 300 K. About room temperature hole centres dissociate with formation of ClO2 radical. It is supposed that part of electron and hole centres is not stabilized but at 77 K it is transformed in stable radiolysis products. This process most effective proceeds in dislocations and on the surface of microcrystals. The suggested model of thermal transformations of primary PC in irradiated perchlorates of alkali metals explains formation of all the finite ion and paramagnetic radiolysis products

  3. Thermal characterization of an AMTEC recirculating test cell. [Alkali Metal ThermoElectric Converter

    Science.gov (United States)

    Underwood, M. L.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Bankston, C. P.

    1990-01-01

    An alkali metal thermoelectric converter (AMTEC) recirculating test cell has been operated in order to determine the magnitudes of the primary heat losses of the cell and the value of the emissivity of the condenser surface. The energy balance included radiation losses, conductive losses, and losses due to the flow of sodium into the cell. The radiative heat flux dominated the heat loss mechanism of the cell at open circuit, and the condenser emissivity was calculated to be about 0.1. It is shown that, if this emissivity can be reduced to 0.02, then parasitic losses in an AMTEC recirculating test cell operating near peak power would be less than 40 percent of the heat required by the cell. The condenser emissivity decreases with elapsed time, resulting in improved thermal performance of the cell.

  4. The alkali metal thermoelectric converter /AMTEC/ - A new direct energy conversion technology for aerospace power

    Science.gov (United States)

    Bankston, C. P.; Cole, T.; Jones, R.; Ewell, R.

    1982-01-01

    A thermally regenerative electrochemical device for the direct conversion of heat to electrical energy, the alkali metal thermoelectric converter (AMTEC), is characterized by potential efficiencies on the order of 15-40% and possesses no moving parts, making it a candidate for space power system applications. Device conversion efficiency is projected on the basis of experimental voltage vs current curves exhibiting power densities of 0.7 W/sq cm and measured electrode efficiencies of up to 40%. Preliminary radiative heat transfer measurements presented may be used in an investigation of methods for the reduction of AMTEC parasitic radiation losses. AMTEC assumes heat input and rejection temperatures of 900-1300 K and 400-800 K, respectively. The working fluid is liquid sodium, and the porous electrode employed is of molybdenum.

  5. Structural systematic and crystal chemistry of novel borates with REE, Pb, Sr, and alkali metals

    International Nuclear Information System (INIS)

    Crystal structures of novel borates with REE, Pb, Sr and alkali metals were analyzed using classical fundamental buildings blocks approach. It is demonstrated that hexa-, penta-, tetra-, tri- and diborates subdivisions in systematic are real families of structures with the common peculiarities. According to the symmetrical way and the degree of FBB condensation structural-generic rows exist in every of subdivisions. Mega- or polyborates subdivision is valid for the structures with the different types of simplest FBB. In all new complex borates it is possible to separate FBB of equal or different types which are presented in isolated form or are connected into chains, layers or frameworks, and to find unexpected correlation between structures. The possibility to recognize and to visualize in this approach the polarity or non-polarity of the structural units and correspondingly the polarity or nonpolarity of the structures in the whole is very important for the conclusion on structure-properties relation. (orig.)

  6. Reasons for different solubility of alkali metal chlorides in cadmium nitrate solutions

    International Nuclear Information System (INIS)

    Maximum solubility of MCl salts (M=Li, Na, K, Cs) in solutions of cadmium nitrate and perchlorate of different concentration was measured in detail for studying the reason for different solubility of alkali metal chlorides in aqueous solutions of cadmium nitrate with concentration of 0.9 and 4.1 mol/l. It is shown that in the framework of phenomenological model of the solutions concentrated solutions of salts forming several crystallohydrates can be considered as a system of mixed solvents. In this case, preferable interaction of LiCl and CsCl with the Cd(NO3)2·9H2O type solvent, while NaCl and KCl - with the Cd(NO3)2·4H2O type solvent can be mentioned

  7. Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

    Science.gov (United States)

    Patki, Gauri Dilip

    mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

  8. High-temperature, high-pressure hydrothermal synthesis, characterization, and structural relationships of mixed-alkali metals uranyl silicates

    Science.gov (United States)

    Chen, Yi-Hsin; Liu, Hsin-Kuan; Chang, Wen-Jung; Tzou, Der-Lii; Lii, Kwang-Hwa

    2016-04-01

    Three mixed-alkali metals uranyl silicates, Na3K3[(UO2)3(Si2O7)2]·2H2O (1), Na3Rb3[(UO2)3(Si2O7)2] (2), and Na6Rb4[(UO2)4Si12O33] (3), have been synthesized by high-temperature, high-pressure hydrothermal reactions at 550 °C and 1440 bar, and characterized by single-crystal X-ray diffraction, photoluminescence, and thermogravimetric analysis. Compound 1 and 2 are isostructural and contain layers of uranyl disilicate. The smaller cation, Na+, is located in the intralayer channels, whereas the larger cations, K+ and Rb+, and water molecule are located in the interlayer region. The absence of lattice water in 2 can be understood according to the valence-matching principle. The structure is related to that of a previously reported mixed-valence uranium(V,VI) silicate. Compound 3 adopts a 3D framework structure and contains a unique unbranched dreier fourfold silicate chain with the structural formula {uB,41∞}[3Si12O33] formed of Q2, Q3, and Q4 Si. The connectivity of the Si atoms in the Si12O3318- anion can be interpreted on the basis of Zintl-Klemm concept. Crystal data for compound 1: triclinic, P-1, a=5.7981(2) Å, b=7.5875(3) Å, c=12.8068(5) Å, α=103.593(2)°, β=102.879(2)°, γ=90.064(2)°, V=533.00(3) Å3, Z=1, R1=0.0278; compound 2: triclinic, P-1, a=5.7993(3) Å, b=7.5745(3) Å, c=12.9369(6) Å, α=78.265(2)°, β=79.137(2)°, γ=89.936(2)°, V=546.02(4) Å3, Z=1, R1=0.0287; compound 3: monoclinic, C2/m, a=23.748(1) Å, b=7.3301(3) Å, c=15.2556(7) Å, β=129.116(2)°, V=2060.4(2) Å3, Z=2, R1=0.0304.

  9. Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide.

    Science.gov (United States)

    Li, Man-Rong; Retuerto, Maria; Stephens, Peter W; Croft, Mark; Sheptyakov, Denis; Pomjakushin, Vladimir; Deng, Zheng; Akamatsu, Hirofumi; Gopalan, Venkatraman; Sánchez-Benítez, Javier; Saouma, Felix O; Jang, Joon I; Walker, David; Greenblatt, Martha

    2016-08-16

    Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic-scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also high pressure in bulk oxide materials. Herein, we present the cationic rearrangement in bulk Mn2 FeMoO6 at unparalleled low temperatures of 150-300 (o) C. The irreversible ionic motion at ambient pressure, as evidenced by real-time powder synchrotron X-ray and neutron diffraction, and second harmonic generation, leads to a transition from a Ni3 TeO6 -type to an ordered-ilmenite structure, and dramatic changes of the electrical and magnetic properties. This work demonstrates a remarkable cationic rearrangement, with corresponding large changes in the physical properties in a bulk oxide at unprecedented low temperatures. PMID:27203790

  10. Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata

    Czech Academy of Sciences Publication Activity Database

    Elicharová, Hana; Sychrová, Hana

    2014-01-01

    Roč. 160, č. 8 (2014), s. 1705-1713. ISSN 1350-0872 R&D Projects: GA ČR GAP302/12/1151; GA MŠk(CZ) ED1.1.00/02.0109 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : Candida glabrata * fluconazole * membrane potential Subject RIV: EE - Microbiology, Virology Impact factor: 2.557, year: 2014

  11. Immobilized poly-L-histidine for chelation of metal cations and metal oxyanions

    International Nuclear Information System (INIS)

    The biohomopolymer poly-L-histidine (PLHis) was immobilized onto controlled pore glass (CPG) and its metal binding capabilities evaluated through the use of a flow injection-flame atomic absorption system. The metal binding capability of PLHis-CPG was determined through the analysis of the generated breakthrough curves. The polymer likely coordinates cationic metals through the imidazole side chain (pKa∼6) present on each histidine residue with both strong and weak binding sites for Cu2+, Cd2+, Co2+, and Ni2+. Weak to minimal binding was observed for Mn2+, Ca2+, Mg2+, Na+, and Cr3+. The bound metals are quantitatively released from the column with an acid strip. It has also been shown that the protonated imidazole side chain present in acidic solutions is capable of binding metal oxyanions such as chromates, arsenates, and selenites; although oxyanion binding currently exhibits interferences from competing anions in solution, such as sulfate and nitrate. The interference in oxyanion binding is less severe in the presence of chloride, phosphate, and acetate. PLHis-CPG exhibits a capacity of ∼30 μmol Cu2+/g CPG in neutral to basic conditions, and a capacity of ∼70 μmol Cr(VI)/g CPG, ∼4 μmol As(V)/g CPG, and ∼4 μmol Se(IV)/g CPG in acidic conditions

  12. Role of CgCnh1 antiporter in tolerance of Candida glabrata to alkali metal cations

    Czech Academy of Sciences Publication Activity Database

    Krauke, Yannick; Sychrová, Hana

    New Jersey : American Society of Microbiology, 2008. s. 46-47. [Candida and Candidiasis /9./. 24.03.2008-28.03.2008, Jersey City] R&D Projects: GA MŠk(CZ) LC531 Institutional research plan: CEZ:AV0Z50110509 Source of funding: R - rámcový projekt EK Keywords : spo2 * Candida glabrata * salt tolerance * antiporter Subject RIV: EE - Microbiology, Virology

  13. Experience in the Design and Operation of High-Temperature Alkali Metal Systems

    International Nuclear Information System (INIS)

    Our experience with the alkali metals began in 1942, when it became necessary to manufacture potassium as an intermediate step in producing potassium superoxide and oxygen generator chemicals for use in rebreather safety equipment evaluation. Study of the alkali metals has continued to the present with measurement of the physical properties, high temperature heat transfer properties, followed by the development of liquid metal instruments and the design and reliable manufacture of components. The present operation (up to 1200°F) of two sodium systems to study the instream mechanical properties of materials for long periods of time reveals the satisfactory operation of many components and the trouble to be experienced when operation is attempted with impurities added to the sodium. Cold-trap purification of 1200°F sodium systems is sufficient for low-corrosion operation over a 2-yr period in an AISI, Type 316 stainless-steel system. The adding of new specimens always raises the oxygen level, requiring repurification of the sodium. Some carbon was removed by the cold trap when high carbon-sodium conditions prevailed, but removal is not complete enough for satisfactory operation; therefore great care should be taken in preventing the carbon contamination. Plugging indicators were a good tool for normal operation. Under high carbon conditions the initial break in the plugging indicator curve can be related to the carburization potential of the sodium. Inert gas lines in sodium systems need to be heated above the melting point of sodium to prevent plugging. However, under high oxygen-sodium conditions, solids deposit in the cover gas regions under ambient temperatures above the melting point of sodium. It is observed that the main difficulty incurred in running with high oxygen - sodium systems is the oxide plugging of small lines. In high carbon sodium systems, the failure of valve bellows by carburization causes operational difficulties. Stability of magnetic flow

  14. Ab initio studies of structural, electronic, magnetic and mechanical properties of alkali earth metal silicides

    International Nuclear Information System (INIS)

    Alkali earth metal silicides MSi (M = Mg, Ca, Sr, Ba) are multi-phase compound and exist simultaneously in CrB, CsCl, NaCl or rock salt (RS) and zinc blende (zb) structures. In the CrB and CsCl phases, their behavior is metallic in the non-magnetic (NM) as well as the ferromagnetic (FM) structure. The total spin magnetic moment of these compounds in the zb phase is more than that in the corresponding RS phase; therefore, detailed studies for the zb phase are presented in this paper. This study includes structural, electronic and mechanical properties by using the full potential linear augmented plain wave scheme with local orbitals. Ferromagnetic CaSi, SrSi and BaSi show true half-metallic character. For a better understanding of the half-metallicity in the above-mentioned sp-type compounds, their band structures have been calculated and densities of state plots have been produced. The FM structures are more stable and harder than the corresponding NM structures. The magnetic moment corresponding to equilibrium lattice constants is calculated as 2 µB for FM CaSi, SrSi and BaSi, which are in accordance with the earlier work on the sp-type compounds CaC, SrC and BaC. The FM character changes to the paramagnetic character as the lattice parameter decreases. The general trend is that the values of the elastic constants C11, C12 and C44 increase with increasing hydrostatic pressure

  15. Elucidating the magnetic and superconducting phases in the alkali metal intercalated iron chalcogenides

    Science.gov (United States)

    Wang, Meng; Yi, Ming; Tian, Wei; Bourret-Courchesne, Edith; Birgeneau, Robert J.

    2016-02-01

    The complex interdigitated phases have greatly frustrated attempts to document the basic features of the superconductivity in the alkali metal intercalated iron chalcogenides. Here, using elastic neutron scattering, energy-dispersive x-ray spectroscopy, and resistivity measurements, we elucidate the relations of these phases in RbxFeySe2 -zSz . We find (i) the iron content is crucial in stabilizing the stripe antiferromagnetic (AF) phase with rhombic iron vacancy order (y ≈1.5 ) , the block AF phase with √{5 }×√{5 } iron vacancy order (y ≈1.6 ) , and the iron vacancy-free phase (y ≈2 ) ; and (ii) the iron vacancy-free superconducting phase (z =0 ) evolves into an iron vacancy-free metallic phase with sulfur substitution (z >1.5 ) due to the progressive decrease of the electronic correlation strength. Both the stripe AF phase and the block AF phase are Mott insulators. The iron-rich compounds (y >1.6 ) undergo a first order transition from an iron vacancy disordered phase at high temperatures into the √{5 }×√{5 } iron vacancy ordered phase and the iron vacancy-free phase below Ts. Our data demonstrate that there are miscibility gaps between these three phases. The existence of the miscibility gaps in the iron content is a key to understanding the relationship between these complicated phases.

  16. Study of complex amalgams containing alkali metals by method of broken thermometric titration

    International Nuclear Information System (INIS)

    Complex potassium-cadmium and sodium-cadmium amalgams containing different amounts of the alkali metal nad cadmium have been studied by thermometric titration with mercury. The experiments have been carried out in argon atmosphere at 25 deg C. As evidenced by the titration of sodium-cadmium amalgams, in the range of concentrations studied (Csub(Na)=0.71-2.95, Csub(Cd)=4.38-6.45 g-at/lHg) no solid phase is formed in them. Potassium-cadmium amalgams where the metals content is no higher than their individual solubility in mercury, display, when being mercury-titrated, negative heat effects due to solid phase formation. An estimation is made of the solid phase composition, its solubility in mercury and the heat of dissolution. The solid phase appearing in complex K-Cd amalgams is likely to contain K and Cd in a ratio 1:1 its conventional solubility product is 5.4 g-at/l Hg, and the heat of dissolution in mercury at 25 deg is -21 +-4 kJ/g-at

  17. Stability of alkali-metal hydrides: effects of n-type doping

    Science.gov (United States)

    Olea Amezcua, Monica Araceli; de La Peña Seaman, Omar; Rivas Silva, Juan Francisco; Heid, Rolf; Bohnen, Klaus-Peter

    Metal hydrides could be considered ideal solid-state hydrogen storage systems, they have light weight and high hydrogen volumetric densities, but the hydrogen desorption process requires excessively high temperatures due to their high stability. Efforts have been performed to improve their dehydrogenation properties, based on the introduction of defects, impurities and doping. We present a systematic study of the n-type (electronic) doping effects on the stability of two alkali-metal hydrides: Na1-xMgxH and Li1-xBexH. These systems have been studied within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the self-consistent version of the virtual crystal approximation to model the doping. The full-phonon dispersions are analyzed for several doping content, paying special attention to the crystal stability. It is found a doping content threshold for each system, where they are close to dynamical instabilities, which are related to charge redistribution in interstitial zones. Applying the quasiharmonic approximation, the vibrational free energy, the linear thermal expansion and heat capacities are obtained for both hydrides systems and are analyzed as a function of the doping content. This work is partially supported by the VIEP-BUAP 2016 and CONACYT-México (No.221807) projects.

  18. Alkali metal pool boiler life tests for a 25 kWe advanced Stirling conversion system

    Science.gov (United States)

    Anderson, W. G.; Rosenfeld, J. H.; Noble, J.

    The overall operating temperature and efficiency of solar-powered Stirling engines can be improved by adding an alkali metal pool boiler heat transport system to supply heat more uniformly to the heater head tubes. One issue with liquid metal pool boilers is unstable boiling. Stable boiling is obtained with an enhanced boiling surface containing nucleation sites that promote continuous boiling. Over longer time periods, it is possible that the boiling behavior of the system will change. An 800-h life test was conducted to verify that pool boiling with the chosen fluid/surface combination remains stable as the system ages. The apparatus uses NaK boiling on a - 100 + 140 stainless steel sintered porous layer, with the addition of a small amount of xenon. Pool boiling remained stable to the end of life test. The pool boiler life test included a total of 82 cold starts, to simulate startup each morning, and 60 warm restarts, to simulate cloud cover transients. The behavior of the cold and warm starts showed no significant changes during the life test. In the experiments, the fluid/surface combination provided stable, high-performance boiling at the operating temperature of 700 C. Based on these experiments, a pool boiler was designed for a full-scale 25-kWe Stirling system.

  19. DETERMINATION OF POTASH ALKALI AND METAL CONTENTS OF ASHES OBTAINED FROM PEELS OF SOME VARIETIES OF NIGERIA GROWN MUSA SPECIES

    Directory of Open Access Journals (Sweden)

    Joshua Olajiire Babayemi

    2010-05-01

    Full Text Available Potash alkali and metal contents of ashes obtained from peels of six varieties of Nigeria Musa species were investigated. The varieties of Musa species – Musa paradisiaca (plantain, Musa ‘Gross Michel’ (Igbo banana, M.sapientum L. (paranta, Musa ‘Wild Banana’ (omini, Musa ‘Red’ (sweet banana, and Musa ‘Fugamo’ (somupeke, were investigated. The moisture, dry matter, ash and alkali contents; concentration of metals in the ashes and in the contents extracted with water from the ashes; and the ratio of potassium to other metals in the ashes and in the corresponding extracts were determined. Moisture contents ranged from 80.9 to 86.7%; dry matter content, 13.3 to 19.1%; ash content, 6.3 to 12.0%; alkali content, 69.0 to 81.9% of ash and 4.7 to 9.6% of dry sample. Samples ranged between 2.60 and 720mg/kg and in the corresponding extracts, BDL to 500.49mg/kg; ratio of concentration of potassium to other metals in the samples, 0.6 to 395; and in the extracts, 0.5 to 313. Gross michel showed the highest concentration of K (750mg/kg while omini banana gave the lowest average value (112.70mg/kg.

  20. Solid State Structures of Alkali Metal Ion Complexes Formed by Low-Molecular-Weight Ligands of Biological Relevance.

    Science.gov (United States)

    Aoki, Katsuyuki; Murayama, Kazutaka; Hu, Ning-Hai

    2016-01-01

    This chapter provides structural data, mainly metal binding sites/modes, observed in crystal structures of alkali metal ion complexes containing low-molecular-weight ligands of biological relevance, mostly obtained from the Cambridge Structural Database (the CSD version 5.35 updated to February 2014). These ligands include (i) amino acids and small peptides, (ii) nucleic acid constituents (excluding quadruplexes and other oligonucleotides), (iii) simple carbohydrates, and (iv) naturally occurring antibiotic ionophores. For some representative complexes of these ligands, some details on the environment of the metal coordination and structural characteristics are described. PMID:26860299

  1. Thermal Decomposition of Anhydrous Alkali Metal Dodecaborates M2B12H12 (M = Li, Na, K)

    OpenAIRE

    Liqing He; Hai-Wen Li; Etsuo Akiba

    2015-01-01

    Metal dodecaborates M2/nB12H12 are regarded as the dehydrogenation intermediates of metal borohydrides M(BH4)n that are expected to be high density hydrogen storage materials. In this work, thermal decomposition processes of anhydrous alkali metal dodecaborates M2B12H12 (M = Li, Na, K) synthesized by sintering of MBH4 (M = Li, Na, K) and B10H14 have been systematically investigated in order to understand its role in the dehydrogenation of M(BH4)n. Thermal decomposition of M2B12H12 indicates m...

  2. Alkali metal ions transfer across a water/1,2-dichloroethane interface facilitated by a novel monoaza-B15C5 derivative

    Energy Technology Data Exchange (ETDEWEB)

    Zhan Dongping; Yuan Yi; Xiao Yanjing; Wu Bingliang; Shao Yuanhua

    2002-10-30

    In this paper, a novel monoaza-B15C5 derivative, N-(2-tosylamino)-isopentyl-monoaza-15-crown-5 (L), is used as an ionophore to facilitate alkali metal cations transfer across a water/1,2-dichloroethane (W/DCE) interface. Well-defined voltammetric behaviors are observed at the polarized W/DCE interfaces supported at micro- and nano-pipets except Cs{sup +}. The diffusion coefficient of this ionophore in the DCE phase is calculated to be equal to (3.3{+-}0.2)x10{sup -6} cm{sup 2} s{sup -1}. The experimental results indicate that a 1:1 (metal:ionophore) complex is formed at the interface with a TIC/TID mechanism. The selectivity of this ionophore towards alkali ions follows the sequence Na{sup +}>Li{sup +}>K{sup +}>Rb{sup +}>Cs{sup +}. The logarithm of the association constants (log {beta}{sub 1}{sup o}) of the LiL{sup +}, NaL{sup +}, KL{sup +} and RbL{sup +} complexes in the DCE phase are calculated to be 10.6, 11.6, 9.0 and 7.1, respectively. The kinetic parameters are determined by steady-state voltammograms using nanopipets. The standard rate constants (k{sup 0}) for Li{sup +}, Na{sup +}, K{sup +} and Rb{sup +} transfers facilitated by L are 0.54{+-}0.05, 0.63{+-}0.09, 0.51{+-}0.04 and 0.46{+-}0.06 cm s{sup -1}, respectively. The pH values of aqueous solution have little effect on the electrochemical behaviors of these facilitated processes. The results predicate that this new type of ionophore might be useful to fabricate electrochemical sensor of sodium ion.

  3. Assessment of Metal Toxicity in Marine Ecosystems: Comparative Toxicity Potentials for Nine Cationic Metals in Coastal Seawater

    DEFF Research Database (Denmark)

    Dong, Yan; Rosenbaum, Ralph K.; Hauschild, Michael Zwicky

    2016-01-01

    ecotoxicity data and take account of metal speciation and bioavailability. CTPs were developed for nine cationic metals (Cd, Cr(III), Co, Cu(II), Fe(III), Mn, Ni, Pb and Zn) in 64 Large Marine Ecosystems (LMEs) covering all coastal waters in the world. The results showed that the CTP of a specific metal...... occurring in coastal seawaters, Fe acts not as a toxic agent but an essential nutrient and thus has CTPs of zero....

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

    Science.gov (United States)

    Nowiak, Grzegorz; Skurski, Piotr; Anusiewicz, Iwona

    2016-04-01

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

  5. MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER- STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

    Institute of Scientific and Technical Information of China (English)

    Xiao-ping Yan; Bao-lin He; Jie Zhang; Han-fan Liu

    2005-01-01

    Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (e.e.) value (71.4%)obtained without the presence of metal cations, obvious e.e. enhancement (up to 82.5%) was resulted from the addition of Zn2+ but with a certain decrease in activity. The reaction parameters in the presence of Zn2+ were also studied. It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.

  6. Enhanced PCBs sorption on biochars as affected by environmental factors: Humic acid and metal cations

    International Nuclear Information System (INIS)

    Biochar plays an important role in the behaviors of organic pollutants in the soil environment. The role of humic acid (HA) and metal cations on the adsorption affinity of polychlorinated biphenyls (PCBs) to the biochars in an aqueous medium and an extracted solution from a PCBs-contaminated soil was studied using batch experiments. Biochars were produced with pine needles and wheat straw at 350 °C and 550 °C under anaerobic condition. The results showed that the biochars had high adsorption affinity for PCBs. Pine needle chars adsorbed less nonplanar PCBs than planar ones due to dispersive interactions and separation. Coexistence of HA and metal cations increased PCBs sorption on the biochars accounted for HA adsorption and cation complexation. The results will aid in a better understanding of biochar sorption mechanism of contaminants in the environment. - Highlights: ► Application of the biochars for PCBs sorption was a new and effective way. ► The biochars had higher adsorption affinity for PCBs in the soil extracted solution. ► Pine needle chars adsorbed less nonplanar PCBs than planar ones. ► Coexisting humic acid or metal cations increased PCBs sorption on the biochars. - The biochars had higher adsorption affinity for PCBs in the extracted soil solution because coexisting humic acid and metal cations increased their sorption.

  7. Hartree-Fock ground-state properties for the group 1 alkali metals and the group 11 noble metals

    International Nuclear Information System (INIS)

    In order to use wavefunction-based correlation methods in solids it is necessary to have reliable Hartree-Fock results for the infinite system of interest. Therefore we performed Hartree-Fock calculations for the group 1 alkali metals (Li to Cs) and group 11 noble metals (Cu, Ag and Au). We optimized a basis set of valence-double-ζ quality for the periodic system. For the lighter atoms all-electron basis sets are applied, whereas for the heavier atoms small-core pseudopotentials with the corresponding basis sets were used to deal with the scalar-relativistic effects. We determine the cohesive energy, the lattice constant and the bulk modulus of the systems at the Hartree-Fock level. We use the counterpoise correction for the free atom to minimize the basis set superposition error occurring for finite basis sets. The effects due to the counterpoise correction not only for the cohesive energy but also for the lattice structure and bulk modulus are discussed in detail

  8. Optical detection of sodium salts of fluoride, acetate and phosphate by a diacylhydrazine ligand by the formation of a colour alkali metal complex

    Indian Academy of Sciences (India)

    Purnandhu Bose; Ranjan Dutta; I Ravikumar; Pradyut Ghosh

    2011-11-01

    A solution of N, N'-diacylhydrazine ligand in organic solvent is potential for colourimetric detection of F−/AcO−/PO$^{3−}_{4}$ via -NH deprotonation, tautomerization and its stabilization as a colour alkali metal complex.

  9. Structure of the Alkali-metal-atom-Strontium molecular ions: towards photoassociation and formation of cold molecular ions

    OpenAIRE

    Aymar, Mireille; Guérout, Romain; Dulieu, Olivier

    2011-01-01

    The potential energy curves, permanent and transition dipole moments, and the static dipolar polarizability, of molecular ions composed of one alkali-metal atom and a Strontium ion are determined with a quantum chemistry approach. The molecular ions are treated as effective two-electron systems and are treated using effective core potentials including core polarization, large gaussian basis sets, and full configuration interaction. In the perspective of upcoming experiments aiming at merging ...

  10. Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

    Science.gov (United States)

    Hartmann, S. R.; Happer, W.

    1974-01-01

    The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

  11. Synergistic solvent extraction of crown ether complexes with alkali metal picrates by neutral donor solvents

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y.

    1983-09-01

    The solvent extraction of rubidium and cesium picrates has been studied at 25/sup 0/C with mixtures of crown ether and tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) in benzene, and the adduct-formation constants in the benzene solution have been calculated. The crown ethers used in this work were 12-crown-4 (12C4), 15-crown-5 (15C5), and benzo-15-crown-5 (B15C5). The stoichiometric composition of any extracted complex under the present experimental conditions is alkali metal ion : crown ether : TBP or TOPO : picrate ion = 1 : 1 : 1 : 1. The TOPO complex is more extractable than the corresponding TBP complex. The extractability of the Rb/sup +/ complex is larger than that of the corresponding Cs/sup +/ complex. For both TBP and TOPO, the adduct-formation constant value sequences of Rb/sup +/ and Cs/sup +/ are B15C5 > 12C4 > 15C5 and 12C4 > B15C5 > 15C5, respectively. 2 figures, 1 table.

  12. Interaction of alkali metals with perylene-3,4,9,10- tetracarboxylic-dianhydride thin films

    International Nuclear Information System (INIS)

    n doping of the molecular organic semiconductor perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) is often achieved by use of alkali metals as dopants. This doping process is commonly performed in two steps. In the first the dopant is evaporated onto the surface of the PTCDA film. As it has been believed that the dopant shows an inhomogeneous diffusion profile through the layer with most of the dopant accumulated in the first few layers, a subsequent annealing step has been performed in order to reach a homogeneous distribution of the dopant in the whole layer. In this paper experimental results concerning chemical composition ((angle resolved) X-ray photoemission spectroscopy, secondary-ion-mass spectrometry, Fourier transform infrared spectroscopy), electronic structure (ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy), as well as electrical properties (conductivity, Seebeck coefficient) are shown before and after doping and before and after annealing. These results suggest that the deposited dopant is redistributed and partially removed during the annealing step. A model for the dopant distribution is suggested

  13. Atomic many-body effects and Lamb shifts in alkali metals

    Science.gov (United States)

    Ginges, J. S. M.; Berengut, J. C.

    2016-05-01

    We present a detailed study of the radiative potential method [V. V. Flambaum and J. S. M. Ginges, Phys. Rev. A 72, 052115 (2005), 10.1103/PhysRevA.72.052115], which enables the accurate inclusion of quantum electrodynamics (QED) radiative corrections in a simple manner in atoms and ions over the range 10 ≤Z ≤120 , where Z is the nuclear charge. Calculations are performed for binding energy shifts to the lowest valence s , p , and d waves over the series of alkali-metal atoms Na to E119. The high accuracy of the radiative potential method is demonstrated by comparison with rigorous QED calculations in frozen atomic potentials, with deviations on the level of 1%. The many-body effects of core relaxation and second- and higher-order perturbation theory on the interaction of the valence electron with the core are calculated. The inclusion of many-body effects tends to increase the size of the shifts, with the enhancement particularly significant for d waves; for K to E119, the self-energy shifts for d waves are only an order of magnitude smaller than the s -wave shifts. It is shown that taking into account many-body effects is essential for an accurate description of the Lamb shift.

  14. Luminescence properties of alkali metal ions sensitized CaFCl:Tb3+ nanophosphors

    Institute of Scientific and Technical Information of China (English)

    林林; 林慧; 王哲哲; 郑标; 谌基兴; 徐森元; 冯卓宏; 郑志强

    2015-01-01

    A series of CaFCl:Tb3+ and CaFCl:Tb3+,A+ (A=Li, Na and K) nanophosphors were synthesized by the one-step sol-gel method, which were reported for the first time. The sample consisted of monodisperse particles, the average size of which was 37 nm. The emissions of Tb3+ ions and oxygen defects OF? were demonstrated in the CaFCl:Tb3+ samples. The former was made up of sev-eral peaks at 488, 545, 587 and 623 nm, ascribed to5D4→7FJ (J=6–3) transitions of Tb3+ ions. The latter was shown as a broad band peaked at about 450 nm. Alkali metal ions A+(A=Li, Na and K) were introduced asthe charge compensators to improve the lumines-cence of samples. The influence of charge compensators on the emissions of Tb3+ ions and oxygen defects OF? was investigated by the measurement of fluorescence spectra and luminescence decay curves. The results indicated that all the charge compensators weakened the defects emission. Furthermore, Li+ ion was the best charge compensator, because it not only reduced the defects emis-sion but also increased the emission intensity of Tb3+ significantly. Our results suggested that this nanophosphor sensitized by the charge compensator might broaden potential applications of rare-earth doped CaFCl.

  15. H- and D- production by backscattering from alkali-metal targets

    International Nuclear Information System (INIS)

    Measurements have been made of the total backscattered D- and H- yields from thick, clean targets of Cs, Rb, K, Na, and Li, bombarded with H+2, H+3, D+2, D+3 with incident energies from 0.15 to 4.0 keV/nucleus. All of the measurements were made at background pressures less than 10-9 Torr, and the alkali-metal targets were evaporated onto a cold substrate (Tapprox.77 K) in situ to assure thick, uncontaminated targets. For each target, the H- and D- yields exhibited maxima (as high as 0.08 per incident proton or deuteron) at incident energies between 0.3 and 1.4 keV/nucleus. For both hydrogen and deuterium incident at any energy, the negative-ion yield decreases in going form Cs to Li in the order given above. Also, a definite isotope effect was observed for every target used, with the H- yield peaking at a lower incident energy than the D- yield and in most cases, the maximum H- yield was higher than the maximum D- yield. Measurements of the D- yield as a function of Cs coverage were also made for D3/sup ts+/ bombarding a Ni substrate. The D- yield maximized at or near the coverage at which the surface work function reached a minimum

  16. Study of Spectral Character of Alkali Metals Using Microwave Plasma Torch Simultaneous Spectrometer

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A microwave plasma torch(MPT) simultaneous spectrometer was used to study the spectral character and the matrix effect on alkali metal ions in solution. The main parameters were optimized. The microwave forward power was 100 W. The argon flow rate that was used to sustain the Ar-MPT included the flow rate of carrier gas and the flow rate of support gas, which were 0.8 and 1.0 L/min, respectively. The HCl concentration in the solution was 0.02 mol/L. The observation height was 9.0 mm. The detection limits of Li, Na, K, Rb, and Cs were 0.0003, 0.0004, 0.009, 0.07 and2.4 mg/L, respectively, and the results obtained by the Ar-MPT were compared with those obtained by argon inductively coupled plasma(Ar-ICP) and argon microwave induced plasma(Ar-MIP). The interference effects of several matrix elements were also studied.

  17. Second virial coefficients and viscosity property of monatomic alkali-metal gases

    International Nuclear Information System (INIS)

    In this work, we have calculated the second virial coefficients B2 of monatomic lithium, sodium, and potassium gases by using the most recent 1Σg+ and 3Σu+ Rydberg-Klein-Rees interatomic potentials. We have also determined the viscosity η and thermal conductivity λ coefficients of the alkali-metal vapors as a function of the temperature T. The results we have found of the collision integrals and of the coefficients η and λ agree quite well with some available experimental data. Besides, we have investigated the variation law with temperature T of the above thermophysical quantities. For temperatures ranging from 100 K to 3,000 K, the results can be reproduced by simple formulas η(T)=ATα and λ(T)=BTα, where for T in Kelvin, η in micropoise, and λ in 10-3 W·m-1·K-1, for lithium Li:A=0.314, B=0.1398, and α=0.863; for sodium Na:A=0.624, B=0.0846, and α=0.827; for potassium K:A=0.400, B=0.0320, and α=0.883. (author)

  18. A Bioluminescence Assay System for Imaging Metal Cationic Activities in Urban Aerosols.

    Science.gov (United States)

    Kim, Sung-Bae; Naganawa, Ryuichi; Murata, Shingo; Nakayama, Takayoshi; Miller, Simon; Senda, Toshiya

    2016-01-01

    A bioluminescence-based assay system was fabricated for an efficient determination of the activities of air pollutants. The following four components were integrated into this assay system: (1) an 8-channel assay platform uniquely designed for simultaneously sensing multiple optical samples, (2) single-chain probes illuminating toxic chemicals or heavy metal cations from air pollutants, (3) a microfluidic system for circulating medium mimicking the human body, and (4) the software manimulating the above system. In the protocol, we briefly introduce how to integrate the components into the system and the application to the illumination of the metal cationic activities in air pollutants. PMID:27424913

  19. Explorations of New SHG Materials in the Alkali-Metal-Nb(5+)-Selenite System.

    Science.gov (United States)

    Cao, Xue-Li; Hu, Chun-Li; Kong, Fang; Mao, Jiang-Gao

    2015-11-16

    Standard high-temperature solid-state reactions of NaCl, Nb2O5, and SeO2 resulted in two new sodium selenites containing a second-order Jahn-Teller (SOJT) distorted Nb(5+) cation, namely, Na2Nb4O7(SeO3)4 (P1̅; 1) and NaNbO(SeO3)2 (Cmc21; 2). Compound 1 exhibits an unusual 3D [Nb4O7(SeO3)4](2-) anionic network composed of 2D [Nb4O11(SeO3)2](6-) layers which are further bridged by additional SeO3(2-) anions via corner sharing; the 2D [Nb4O11(SeO3)2](6-) layer is formed by unusual quadruple [Nb4O17](14-) niobium oxide chains of corner-sharing NbO6 octahedra being further interconnected by selenite anions via Nb-O-Se bridges. The polar compound 2 features a 1D [NbO(SeO3)2](-) anionic chain in which two neighboring Nb(5+) cations are bridged by one oxo and two selenite anions. The alignments of the polarizations from the NbO6 octahedra in 2 led to a strong SHG response of ∼7.8 × KDP (∼360 × α-SiO2), which is the largest among all phases found in metal-Nb(5+)-Se(4+)/metal-Nb(5+)-Te(4+)-O systems. Furthermore, the material is also type I phase matchable. The above experimental results are consistent with those based on DFT theoretical calculations. Thermal stabilities and optical properties for both compounds are also reported. PMID:26513233

  20. Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

    Science.gov (United States)

    Kuzmina, O; Bordes, E; Schmauck, J; Hunt, P A; Hallett, J P; Welton, T

    2016-06-28

    The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids. PMID:27264676

  1. Design and Test of Advanced Thermal Simulators for an Alkali Metal-Cooled Reactor Simulator

    Science.gov (United States)

    Garber, Anne E.; Dickens, Ricky E.

    2011-01-01

    The Early Flight Fission Test Facility (EFF-TF) at NASA Marshall Space Flight Center (MSFC) has as one of its primary missions the development and testing of fission reactor simulators for space applications. A key component in these simulated reactors is the thermal simulator, designed to closely mimic the form and function of a nuclear fuel pin using electric heating. Continuing effort has been made to design simple, robust, inexpensive thermal simulators that closely match the steady-state and transient performance of a nuclear fuel pin. A series of these simulators have been designed, developed, fabricated and tested individually and in a number of simulated reactor systems at the EFF-TF. The purpose of the thermal simulators developed under the Fission Surface Power (FSP) task is to ensure that non-nuclear testing can be performed at sufficiently high fidelity to allow a cost-effective qualification and acceptance strategy to be used. Prototype thermal simulator design is founded on the baseline Fission Surface Power reactor design. Recent efforts have been focused on the design, fabrication and test of a prototype thermal simulator appropriate for use in the Technology Demonstration Unit (TDU). While designing the thermal simulators described in this paper, effort were made to improve the axial power profile matching of the thermal simulators. Simultaneously, a search was conducted for graphite materials with higher resistivities than had been employed in the past. The combination of these two efforts resulted in the creation of thermal simulators with power capacities of 2300-3300 W per unit. Six of these elements were installed in a simulated core and tested in the alkali metal-cooled Fission Surface Power Primary Test Circuit (FSP-PTC) at a variety of liquid metal flow rates and temperatures. This paper documents the design of the thermal simulators, test program, and test results.

  2. Effect of alkali metals on the interaction of O2 and CO with some transition-metal surfaces

    International Nuclear Information System (INIS)

    The interactions of O2 and CO with alkali covered Ni, Ru, and Pt are reviewed with emphasis on the author's own studies. It is shown that the presence of alkalis changes the coadsorbates adsorption rates, heats of adsorption, and dissociative propensity, the strength of the effect depending on the alkali nature and coverage. The differences for the three substrates are interpreted comparing the properties of the clean surface. A detailed analysis of the coadsorbate--modifier interactions suggests that they depend on the adsorption state of the alkali species and the coadsorbate--substrate bond strength. Evidence of the formation of patches of ''surface complexes'' coexisting with the unperturbed surface is given and discussed in terms of strong direct alkali--coadsorbate interactions

  3. Effect of metallic Si addition on polymerization degree of in situ foamed alkali-aluminosilicates

    Czech Academy of Sciences Publication Activity Database

    Medri, V.; Papa, E.; Dědeček, Jiří; Jirglová, Hana; Benito, P.; Vaccari, A.; Landi, E.

    2013-01-01

    Roč. 39, č. 7 (2013), s. 7657-7668. ISSN 0272-8842 Institutional support: RVO:61388955 Keywords : B. porosity * alkali-bonded ceramics * geopolymerization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.086, year: 2013

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

    International Nuclear Information System (INIS)

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

  5. Synthesis and properties of alkali metal intercalated fullerene-like MS2 (M=W,Mo) nanoparticles

    International Nuclear Information System (INIS)

    Layered metal disulfides - MoS2 and WS2 in the form of fullerene-like (IF) nanoparticles and in the form of platelets (crystallites of the 2H polytype) have been intercalated by exposure to alkali metal (potassium and sodium) vapor using a two-zone transport method. The composition of the intercalated systems was established using X-ray energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). X-ray powder diffraction (XRD) analysis and transmission electron microscopy (TEM) of the samples, which were not exposed to the ambient atmosphere, showed that they suffered little change in their lattice parameters. On the other hand, after exposure to ambient atmosphere, substantial increase in the interplanar spacing (3-5 Aa) was observed for the intercalated phases. Insertion of one to two water molecules per intercalated metal atom was suggested as a possible explanation for this large expansion along the c-axis. The modifications in magnetic and transport properties of the intercalated materials were investigated, and are believed to occur via charge transfer from the alkali metal to the conduction band of the host lattice. Restacking of the MS2 layers after prolonged exposure to the atmosphere and recovery of the pristine compound properties were observed as a result of deintercalation of the metal atoms

  6. Hydrogen production coupled to nuclear waste treatment: the safe treatment of alkali metals through a well-demonstrated process

    International Nuclear Information System (INIS)

    In 1992, the United Nations emphasised the urgent need to act against the perpetuation of disparities between and within nations, the worsening of poverty, hunger, ill health and illiteracy and the continuing deterioration of ecosystems on which we depend for our well-being. In this framework, taking into account the preservation of both worldwide energy resources and ecosystems, the use of nuclear energy to produce clean energy carriers, such as hydrogen, is undoubtedly advisable. However, coping fully with the Agenda 21 statements requires defining adequate treatment processes for nuclear wastes. This paper discusses the possible use of a well-demonstrated process to convert radioactively contaminated alkali metals into sodium hydroxide while producing hydrogen. We conclude that a synergy between Chlor-Alkali specialists and nuclear specialists may help find an acceptable solution for radioactively contaminated sodium waste. (author)

  7. N-alkyl pyrrolidone ether podands as versatile alkali metal ion chelants.

    Science.gov (United States)

    Perrin, Andrea; Myers, Dominic; Fucke, Katharina; Musa, Osama M; Steed, Jonathan W

    2014-02-28

    This work explores the coordination chemistry of a bis(pyrrolidone) ether ligand. Pyrrolidones are commercially important functional groups because of the high polarity and hence high hydrophilicity and surface affinity. An array of alkali metal ion complexes of a podand bearing two pendant pyrrolidone functionalities, namely 1-{2-[2-(2-oxo-pyrrolid-1-yl)-ethoxy]-ethyl}-pyrrolid-2-one (1) are reported. Reaction of this ligand with sodium hexafluorophosphate gives two discrete species of formulae [Na(1)2]PF6 (3) and [Na3(H2O)2(μ-1)2](PF6)3 (4), and a coordination polymer {[Na3(μ3-1)3(μ2-1)](PF6)3}n (5). The same reaction in methanol gives a 1 : 1 complex, namely [Na2(μ-1)2(MeOH)2](PF6)2 (6). Use of tetraphenyl borate as a less coordinating counter ion gives [Na2(1)2(H2O)4](BPh4)2 (7) and [Na2(1)4](BPh4)2 (8). Two potassium complexes have also been isolated, a monomer [K(1)2]PF6 (9) and a cyclic tetramer [K4(μ4-H2O)2(μ-1)4](PF6)4 (10). The structures illustrate the highly polar nature of the amide carbonyl moiety within bis(pyrrolidone) ethers with longer interactions to the ether oxygen atom. The zinc complex is also reported and {[ZnCl2(μ-1)]}n (11) exhibits bonding only to the carbonyl moieties. The ether oxygen atom is not necessary for Na(+) complexation as exemplified by the structure of the sodium complex of the analogue 1,3-bis(pyrrolid-2-on-1-yl)butane (2). Reaction of compound 1 with lithium salts results in isolation of the protonated ligand. PMID:24336897

  8. Theoretical investigation on the alkali-metal doped BN fullerene as a material for hydrogen storage

    International Nuclear Information System (INIS)

    Graphical abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. Adsorption of alkali atoms involves a charge transfer process, creating positively-charged alkali atoms and this polarizes the H2 molecules and increases their binding energy. The maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 H2 were adsorbed in molecular form. - Abstract: First-principles calculations have been used to investigate hydrogen adsorption on alkali atom doped B36N36 clusters. The alkali atom adsorption takes place near the six tetragonal bridge sites available on the cage, thereby avoiding the notorious clustering problem. Adsorption of alkali atoms involves a charge transfer process, creating positively charged alkali atoms and this polarizes the H2 molecules thereby, increasing their binding energy. Li atom has been found to adsorb up to three hydrogen molecules with an average binding energy of 0.189 eV. The fully doped Li6B36N36 cluster has been found to hold up to 18 hydrogen molecules with the average binding energy of 0.146 eV. This corresponds to a gravimetric density of hydrogen storage of 3.7 wt.%. Chemisorption on the Li6B36N36 has been found to be an exothermic reaction, in which 60 hydrogen atoms chemisorbed with an average chemisorption energy of -2.13 eV. Thus, the maximum hydrogen storage capacity of Li doped BN fullerene is 8.9 wt.% in which 60 hydrogen atoms were chemisorbed and 12 hydrogen molecules were adsorbed in molecular form.

  9. Nitrogen-Rich Multinuclear Ferrocenophanes as Multichannel Chemosensor Molecules for Transition and Heavy-Metal Cations

    Directory of Open Access Journals (Sweden)

    Antonia Sola

    2014-08-01

    Full Text Available [m.n] Multinuclear ferrocenophanes prepared by aza-Wittig reaction of bisiminophosphoranes derived from 1,1'-diazidoferrocene and isophthaladelhyde or 2,5-diformylthiophene, behave as efficient electrochemical and chromogenic chemosensor molecules for Zn2+, Pb2+, and Hg2+ metal cations. Whereas the OSWV of receptor 3, bearing two m-phenylene units in the bridges, display one oxidation peak, receptor 4 incorporating two thiophene rings in the bridges, exhibits two well-separated oxidation peaks. In both receptors only the addition of Zn2+, Pb2+, and Hg2+ metal cations induced a remarkable anodic shift of ferrocene/ferrocenium redox couple. Likewise, in the absorption spectra of these receptors the low energy band is red-shifted by Δλ = 165 − 209 nm, and these changes promoted a significant color changes which could be used for the naked eye detection of these metal cations. The coordination modes for two representative cases were unveiled by DFT calculations that show an unsual coordination in the [42Pb]2+ complex with the Pb2+ cation in a distorted cubic N4S4 donor cage.

  10. Plasma assisted measurements of alkali metal concentrations in pressurised combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland)

    1997-10-01

    In this project the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) was developed, tested and demonstrated in pressurised combustion facilities. The PEARLS method has been developed at Tampere University of Technology (TUT). During 1994-1996 the PEARLS method was developed from the laboratory level to an industrial prototype. The alkali measuring instrument has been tested and used for regular measurements in four different pressurised combustion installations ranging up to industrial pilot scale. The installations are: (1) a pressurised entrained flow reactor (PEFR) at VTT Energy in Jyvaeskylae, Finland (2) a pressurised fluidised bed combustion facility, called FRED, at DMT in Essen, Germany. (3) a 10 MW pressurised circulating fluidised bed combustion pilot plant at Foster Wheeler Energia Oy in Karhula, Finland (4) PFBC Research Facility at ABB Carbon in Finspaang, Sweden

  11. Relation of physico-chemical properties of electrolytes with electronic structure of solvated alkali metal ions

    International Nuclear Information System (INIS)

    The nature of bonds, their strength and, accordingly, electric mobility of cation and electrolyte viscosity depending on the type of cation (Li+, Na+, K+, Rb+, Cs+) and molecules (H2O, NH3, H2CO, (CH3)2CO, CH3CN) were ascertained by the method of theoretical-group analysis and linear combinations of solvent cation and molecules orbitals. Regularities of solvation effect on electronic UV-, intramolecular vibrational IR and NMR spectra were revealed

  12. Coordination polymers based on diiron tetrakis(dithiolato) bridged by alkali metals, electrical bistability around room temperature, and strong antiferromagnetic coupling.

    Science.gov (United States)

    Benmansour, Samia; Delgado, Esther; Gómez-García, Carlos J; Hernández, Diego; Hernández, Elisa; Martin, Avelino; Perles, Josefina; Zamora, Félix

    2015-03-01

    Coordination polymer chains have been formed by the direct reaction between HSC6H2Cl2SH and FeCl3·6H2O in the presence of an aqueous solution of the corresponding alkali-metal hydroxide (M = Li, Na, and K) or carbonate (M = Rb and Cs). The structures consist of dimeric [Fe2(SC6H2Cl2S)4](2-) entities bridged by [M2(THF)4] [M = K (1), Rb (2), and Cs (3); THF = tetrahydrofuran] or {[Na2(μ-H2O)2(THF)2] (5 and 5') units. The smaller size of the lithium atom yields an anion/cation ion-pair molecule, [Li(THF)4]2[Fe2(SC6H2Cl2S)4] (4), in which the dianionic moieties are held together by Cl···Cl interactions. Electrical characterization of these compounds shows a general semiconductor behavior in which the conductivity and activation energies are mainly determined by the M-Cl and M-S bond distances. Compounds 1 and 5' are interesting examples of bistability showing reversible transitions centered at ca. 350 and 290 K with very large hysteresis of ca. 60 and 35 K, respectively. All of these compounds exhibit intradimer strong antiferromagnetic Fe···Fe interactions. PMID:25667965

  13. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin

    2014-03-24

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Alkali-Metal-Ion-Functionalized Graphene Oxide as a Superior Anode Material for Sodium-Ion Batteries.

    Science.gov (United States)

    Wan, Fang; Li, Yu-Han; Liu, Dai-Huo; Guo, Jin-Zhi; Sun, Hai-Zhu; Zhang, Jing-Ping; Wu, Xing-Long

    2016-06-01

    Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions. PMID:27136376

  15. Cooper minima in the transitions from low-excited and Rydberg states of alkali-metal atoms

    OpenAIRE

    Beterov, I. I.; Mansell, C. W.; Yakshina, E. A.; Ryabtsev, I. I.; Tretyakov, D. B.; Entin, V. M.; MacCormick, C.; Piotrowicz, M. J.; Kowalczyk, A.; S. Bergamini

    2012-01-01

    The structure of the Cooper minima in the transition probabilities and photoionization cross-sections for low-excited and Rydberg nS, nP, nD and nF states of alkali-metal atoms has been studied using a Coulomb approximation and a quasiclassical model. The range of applicability of the quasiclassical model has been defined from comparison with available experimental and theoretical data on dipole moments, oscillator strengths, and photoionization cross-sections. A new Cooper minimum for transi...

  16. Cooper minima in the transitions from low-excited and Rydberg states of alkali-metal atoms

    CERN Document Server

    Beterov, I I; Yakshina, E A; Ryabtsev, I I; Tretyakov, D B; Entin, V M; MacCormick, C; Piotrowicz, M J; Kowalczyk, A; Bergamini, S

    2012-01-01

    The structure of the Cooper minima in the transition probabilities and photoionization cross-sections for low-excited and Rydberg nS, nP, nD and nF states of alkali-metal atoms has been studied using a Coulomb approximation and a quasiclassical model. The range of applicability of the quasiclassical model has been defined from comparison with available experimental and theoretical data on dipole moments, oscillator strengths, and photoionization cross-sections. A new Cooper minimum for transitions between rubidium Rydberg states has been found.

  17. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    International Nuclear Information System (INIS)

    We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system

  18. Nuclear Wavepacket Dynamics of Alkali Adsorbates on Metal Surfaces Studied by Time-Resolved Second Harmonic Generation

    Directory of Open Access Journals (Sweden)

    Kazuya Watanabe

    2012-01-01

    Full Text Available This paper reviews recent efforts to understand the dynamics of coherent surface vibrations of alkali atoms adsorbed on metal surfaces. Time-resolved second harmonic generation is used for the coherent excitation and detection of the nuclear wavepacket dynamics of the surface modes. The principles of the measurement and the experimental details are described. The main focus is on coverage and excitation photon energy dependences of the coherent phonon dynamics for Na-, K-, and Cs-covered Cu(111. The excitation mechanism of the coherent phonon has been revealed by the ultrafast time-domain technique and theoretical modelings.

  19. Thermophysical properties of alkali metal vapours. Part II - assessment of experimental data on thermal conductivity and viscosity

    OpenAIRE

    Fialho, Paulo; Ramires, Maria de Lurdes V.; Nieto de Castro, Carlos A.; João M. N. A. Fareleira; Mardolcar, Umesh V.

    1994-01-01

    Copyright © 1994 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Article first published online: 8 MAY 2010. An analysis of the available data on the viscosity and thermal conductivity coefficients of the alkali metal vapours is presented. The analysis is based upon theoretical calculations of the properties of the monatomic systems, described in the preceding parts I and I.A of the present paper, and making use of the kinetic theory of a binary gas reacting mixture. A summary of the measur...

  20. Collimated, single-pass atom source from a pulsed alkali metal dispenser for laser-cooling experiments

    International Nuclear Information System (INIS)

    We have developed an improved scheme for loading atoms into a magneto-optical trap (MOT) from a directed rubidium alkali metal dispenser in -10 Torr ultrahigh vacuum conditions. A current-driven dispenser was surrounded with a cold absorbing 'shroud' held at ≤0 deg. C, pumping rubidium atoms not directed into the MOT. This nearly eliminates background atoms and reduces the detrimental rise in pressure normally associated with these devices. The system can be well-described as a current-controlled, rapidly switched, two-temperature thermal beam, and was used to load a MOT with 3x108 atoms

  1. Sensitive determination of the spin polarization of optically pumped alkali-metal atoms using near-resonant light.

    Science.gov (United States)

    Ding, Zhichao; Long, Xingwu; Yuan, Jie; Fan, Zhenfang; Luo, Hui

    2016-01-01

    A new method to measure the spin polarization of optically pumped alkali-metal atoms is demonstrated. Unlike the conventional method using far-detuned probe light, the near-resonant light with two specific frequencies was chosen. Because the Faraday rotation angle of this approach can be two orders of magnitude greater than that with the conventional method, this approach is more sensitive to the spin polarization. Based on the results of the experimental scheme, the spin polarization measurements are found to be in good agreement with the theoretical predictions, thereby demonstrating the feasibility of this approach. PMID:27595707

  2. Third order nonlinear optical properties and optical limiting behavior of alkali metal complexes of p-nitrophenol

    Science.gov (United States)

    Thangaraj, M.; Vinitha, G.; Sabari Girisun, T. C.; Anandan, P.; Ravi, G.

    2015-10-01

    Optical nonlinearity of metal complexes of p-nitrophenolate (M=Li, Na and K) in ethanol is studied by using a continuous wave (cw) diode pumped Nd:YAG laser (532 nm, 50 mW). The predominant mechanism of observed nonlinearity is thermal in origin. The nonlinear refractive index and the nonlinear absorption coefficient of the samples were found to be in the order of 10-8 cm2/W and 10-3 cm/W respectively. Magnitude of third-order optical parameters varies according to the choice of alkali metal chosen for metal complex formation of p-nitrophenolate. The third-order nonlinear susceptibility was found to be in the order of 10-6 esu. The observed saturable absorption and the self-defocusing effect were used to demonstrate the optical limiting action at 532 nm by using the same cw laser beam.

  3. Alkali metal salts of rutin - Synthesis, spectroscopic (FT-IR, FT-Raman, UV-VIS), antioxidant and antimicrobial studies.

    Science.gov (United States)

    Samsonowicz, M; Kamińska, I; Kalinowska, M; Lewandowski, W

    2015-12-01

    In this work several metal salts of rutin with lithium, sodium, potassium, rubidium and cesium were synthesized. Their molecular structures were discussed on the basis of spectroscopic (FT-IR, FT-Raman, UV-VIS) studies. Optimized geometrical structure of rutin was calculated by B3LYP/6-311++G(∗∗) method and sodium salt of rutin were calculated by B3LYP/LanL2DZ method. Metal chelation change the biological properties of ligand therefore the antioxidant (FRAP and DPPH) and antimicrobial activities (toward Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida albicans and Saccharomyces cerevisiae) of alkali metal salts were evaluated and compared with the biological properties of rutin. PMID:26184478

  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. Similarities and differences of alkali metal chlorides applied in organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lue, Zhaoyue [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Deng, Zhenbo [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Hou, Ying [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Xu, Haisheng, E-mail: hsxu@ecust.edu.cn [Department of Physics, School of Science, East China University of Science and Technology, Shanghai 200237 (China); Kunshan Hisense Electronics, Co., Ltd., Kunshan, Jiangsu 215300 (China)

    2012-12-15

    The similarities and differences of alkali metal chlorides (sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl) and cesium chloride (CsCl)) applied in organic light-emitting diodes (OLEDs) are investigated. The behavior is similar for the OLEDs with these four chlorides as electron injection layer (EIL). Their maximum luminance and efficiency at 100 mA/cm{sup 2} are within the ranges of 18 550 {+-} 600 (cd/m{sup 2}) with an error of 3.23% and 4.09 {+-} 0.15 (cd/A) within an error of 3.67%, respectively. The similar performance is due to almost identical electron injection barrier for NaCl, KCl, RbCl and CsCl as EIL. Interestingly, the properties are different for devices with chlorides inserted inside tris (8-hydroxyquinoline) aluminum at the position of 20 nm away from aluminum cathode, labeled as NaCl-, KCl-, RbCl- and CsCl- devices. The relation of luminance is CsCl- > RbCl- = KCl- > NaCl-, where '>' and '=' mean 'better than' and 'the same as', respectively. And the device efficiencies are decreased from CsCl to NaCl. That is, the sort order of the efficiencies is CsCl- > RbCl- > KCl- > NaCl-. The mechanism is explained by tunneling model in terms of various energy gaps estimated by optical electronegativity of NaCl, KCl, RbCl and CsCl. - Highlights: Black-Right-Pointing-Pointer Effects of NaCl, KCl, RbCl and CsCl in organic light-emitting diodes are compared. Black-Right-Pointing-Pointer The similar performance is due to almost identical electron injection barrier. Black-Right-Pointing-Pointer The different behavior of chlorides inside Alq{sub 3} is explained by tunneling model. Black-Right-Pointing-Pointer The different behavior is attributed to various energy gaps of different chlorides. Black-Right-Pointing-Pointer The efficiency of device with chlorides inside Alq{sub 3} is decreased from CsCl to NaCl.

  6. Preparation, characterization and applications of novel iminodiacetic polyurethane foam (IDA-PUF) for determination and removal of some alkali metal ions from water

    International Nuclear Information System (INIS)

    The new type of ion chelating resin (IDA-PUF) has iminodiacetic group that was prepared from polyurethane foam (PUF) by the reaction between primary amine of PUF and monochloro-acetic acid. The IDA-PUF was characterized using infrared spectra, elemental and thermal analysis. The exchange properties and chromatographic behaviour of the new chelating resin were investigated for removal of some alkali metal ions (lithium, sodium and potassium) using batch and column processes. The maximum distribution coefficient (KD) of trace alkali metal ions was in the pH range of 8-10. The kinetics of sorption of the alkali metal ions was found to be fast with average values of half-life of sorption (t1/2) of 4.93 min. The values of ΔG, ΔS and ΔH were -3.86 kJ mol-1, 57.73 J mol-1 K-1 and 14.41 kJ mol-1, respectively, which reflects the spontaneous and endothermic nature of ion exchanger process. The average sorption capacity of IDA-PUF is 4.8 mmol/g for alkali metal ions, enrichment factors ∼40 and the recovery 95-100% were also achieved with average value of RSD% = 1.67. The proposed method has been successfully applied to preconcentrate, determinate and remove the alkali metal ions from different samples of water

  7. Phase behaviour and thermodynamics of poly(1,4-phenylene ether sulphone) and poly(ethylene oxide)/alkali-metal salt complex blends: a thermal analysis study

    International Nuclear Information System (INIS)

    The phase behaviour and thermodynamics of poly(1,4-phenylene ether sulfone) (PES) and poly(ethylene oxide) (PEO)/alkali-metal salt complex blends were investigated by means of differential scanning calorimetry (DSC) and modulated DSC (MDSC). Experimental results show that the blend systems remain miscible after incorporating various alkali-metal salts: CF3SO3Li, CF3SO3Na and CF3SO3K. The cloud point temperature strongly depended on the Li (Na or K)/O ratio in the PES-PEO/alkali-metal salt complex blends. With increasing the Li+ (Na+ or K+)/O ratio, the phase diagram of the PES-PEO/alkali-metal salt complex blends tended to be symmetrical. When Li+/O = 0.02, the lower critical solution temperature (LCST) of the PES-PEO/CF3SO3Li complex blends was located at the 30/70 PES/PEO composition. The mixing enthalpy decreased in the PES-PEO/alkali-metal salt complex blends with increasing Li+ (Na+ or K+)/O ratio. The radius of ion has significant influence on the phase behaviour of PES/PEO blends. MDSC results showed that the change of heat capacity at the temperature of the binodal phase separation is similar to that of a melt transition in semi-crystalline polymers, which confirms the mechanism of binodal phase separation: nucleation and growth

  8. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    International Nuclear Information System (INIS)

    The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y3+ is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH4 both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A3Y(BH4)6 or c-A2LiY(BH4)6 (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH4)4 crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y3+ is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH4)4 structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH4 (A=K, Rb, Cs) contains nine compounds in total. • Y3+ forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH4)4 crystallize with structure types analogous to metal oxides. • Double-perovskites decompose and form a novel borohydride-closo-borane

  9. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    Energy Technology Data Exchange (ETDEWEB)

    Sadikin, Yolanda [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Stare, Katarina [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Schouwink, Pascal [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Brix Ley, Morten; Jensen, Torben R. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Århus C (Denmark); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Černý, Radovan, E-mail: radovan.cerny@unige.ch [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland)

    2015-05-15

    The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y{sup 3+} is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH{sub 4} both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A{sub 3}Y(BH{sub 4}){sub 6} or c-A{sub 2}LiY(BH{sub 4}){sub 6} (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH{sub 4}){sub 4} crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y{sup 3+} is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH{sub 4}){sub 4} structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH{sub 4} (A=K, Rb, Cs) contains nine compounds in total. • Y{sup 3+} forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH{sub 4}){sub 4} crystallize with

  10. Alkali metal and ammonium chlorides in water and heavy water (binary systems)

    CERN Document Server

    Cohen-Adad, R

    1991-01-01

    This volume surveys the data available in the literature for solid-fluid solubility equilibria plus selected solid-liquid-vapour equilibria, for binary systems containing alkali and ammonium chlorides in water or heavy water. Solubilities covered are lithium chloride, sodium chloride, potassium chloride, rubidium chloride, caesium chloride and ammonium chloride in water and heavy water.

  11. Plasma assisted measurements of alkali metal concentrations in pressurized combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland). Dept. of Physics

    1996-12-01

    The plasma assisted method for continuous measurement of alkali concentrations in product gas flows of pressurized energy processes will be tested and applied at the 1.6 MW PFBC/G facility at Delft University of Technology in the Netherlands. During the reporting period the alkali measuring device has been tested under pressurized conditions at VTT Energy, DMT, Foster-Wheeler Energia and ABB Carbon. Measurements in Delft will be performed during 1996 after installation of the hot gas filter. The original plan for measurements in Delft has been postponed due to schedule delays in Delft. The results are expected to give information about the influence of different process conditions on the generation of alkali vapours, the comparison of different methods for alkali measurement and the specific performance of our system. This will be the first test of the plasma assisted measurement method in a gasification process. The project belongs to the Joule II extension program under contract JOU2-CT93-0431. (author)

  12. Superconductivity and electrical resistivity in alkali metal doped fullerides: Phonon mechanism

    Indian Academy of Sciences (India)

    Dinesh Varshney; A Dube; K K Choudhary; R K Singh

    2005-04-01

    We consider a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. We first study the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C60 phonons. Electronic parameter as repulsive parameter and the attractive coupling strength are obtained within the random phase approximation. Transition temperature, c, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C60 phonons as 5 K, which is much lower as compared to reported c (≈ 20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. To illustrate the usefulness of the above approach, the carbon isotope exponent and the pressure effect are also estimated. Temperature dependence of electrical resistivity is then analysed within the same model phonon spectrum. It is inferred from the two-peak model for phonon density of states that high frequency intramolecular phonon modes play a major role in pairing mechanism with possibly some contribution from alkali-C60 phonon to describe most of the superconducting and normal state properties of doped fullerides.

  13. Electromembrane extraction of heavy metal cations followed by capillary electrophoresis with capacitively coupled contactless conductivity detection

    Czech Academy of Sciences Publication Activity Database

    Kubáň, Pavel; Strieglerová, Lenka; Gebauer, Petr; Boček, Petr

    2011-01-01

    Roč. 32, č. 9 (2011), s. 1025-1032. ISSN 0173-0835 R&D Projects: GA ČR GA203/08/1536; GA ČR GAP206/10/1219; GA AV ČR IAA400310703 Institutional research plan: CEZ:AV0Z40310501 Keywords : capillary electrophoresis * electromembrane extraction * heavy metal cations Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.303, year: 2011

  14. Study of complexation between two 1,3-alternate calix[4]crown derivatives and alkali metal ions by electrospray ionization mass spectrometry and density functional theory calculations

    Science.gov (United States)

    Shamsipur, Mojtaba; Allahyari, Leila; Fasihi, Javad; Taherpour, Avat (Arman); Asfari, Zuhair; Valinejad, Azizollah

    2016-03-01

    Complexation of two 1,3-alternate calix[4]crown ligands with alkali metals (K+, Rb+ and Cs+) has been investigated by electrospray ionization mass spectrometry (ESI-MS) and density functional theory calculations. The binding selectivities of the ligands and the binding constants of their complexes in solution have been determined using the obtained mass spectra. Also the percentage of each formed complex species in the mixture of each ligand and alkali metal has been experimentally evaluated. For both calix[4]crown-5 and calix[4]crown-6 ligands the experimental and theoretical selectivity of their alkali metal complexes found to follow the trend K+ > Rb+ > Cs+. The structures of ligands were optimized by DFT-B3LYP/6-31G method and the structures of complexes were obtained by QM-SCF-MO/PM6 method and discussed in the text.

  15. XPS studies and photocurrent applications of alkali-metals-doped ZnO nanoparticles under visible illumination conditions

    Science.gov (United States)

    Saáedi, Abdolhossein; Yousefi, Ramin; Jamali-Sheini, Farid; Zak, Ali Khorsand; Cheraghizade, Mohsen; Mahmoudian, M. R.; Baghchesara, Mohammad Amin; Dezaki, Abbas Shirmardi

    2016-05-01

    The present work is a study about a relationship between X-ray photoelectron spectrometer (XPS) results and photocurrent intensity of alkali-metals-elements doped ZnO nanoparticles, which is carried out under visible illumination conditions. The nanoparticles were synthesized by a simple sol-gel method. Structure and morphology studies of the NPs were carried out by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The effect of doping on the optical band-gap was investigated by using UV-visible spectrometer. The absorption peak of the doped ZnO NPs was red-shifted with respect to that of the undoped ZnO NPs. After that, the photocurrent application of the products was examined under a white light source at 2 V bias. The photocurrent results showed that, the current intensity of the ZnO NPs was increased by doping materials. However, K-doped ZnO NPs showed the highest photocurrent intensity. Finally, a discussion was carried out about the obtained photocurrent results by the O-1s spectra of the XPS of the samples. Our results suggest that the alkali-metals-doped ZnO NPs exhibit considerable promise for highly sensitive visible-light photodetectors.

  16. Structural and electronic engineering of 3DOM WO3 by alkali metal doping for improved NO2 sensing performance.

    Science.gov (United States)

    Wang, Zhihua; Fan, Xiaoxiao; Han, Dongmei; Gu, Fubo

    2016-05-19

    Novel alkali metal doped 3DOM WO3 materials were prepared using a simple colloidal crystal template method. Raman, XRD, SEM, TEM, XPS, PL, Hall and UV-Vis techniques were used to characterize the structural and electronic properties of all the products, while the corresponding sensing performances targeting ppb level NO2 were determined at different working temperatures. For the overall goal of structural and electronic engineering, the co-effect of structural and electronic properties on the improved NO2 sensing performance of alkali metal doped 3DOM WO3 was studied. The test results showed that the gas sensing properties of 3DOM WO3/Li improved the most, with the fast response-recovery time and excellent selectivity. More importantly, the response of 3DOM WO3/Li to 500 ppb NO2 was up to 55 at room temperature (25 °C). The especially high response to ppb level NO2 at room temperature (25 °C) in this work has a very important practical significance. The best sensing performance of 3DOM WO3/Li could be ascribed to the most structure defects and the highest carrier mobility. And the possible gas sensing mechanism based on the model of the depletion layer was proposed to demonstrate that both structural and electronic properties are responsible for the NO2 sensing behavior. PMID:27109698

  17. A high-performance "sweeper" for toxic cationic herbicides: an anionic metal-organic framework with a tetrapodal cage.

    Science.gov (United States)

    Jia, Yan-Yuan; Zhang, Ying-Hui; Xu, Jian; Feng, Rui; Zhang, Ming-Shi; Bu, Xian-He

    2015-12-21

    This communication reports a novel metal-organic framework exhibiting an excellent performance in adsorbing small toxic cationic herbicides, i.e. methyl viologen and diquat, with large adsorption capacities and ultratrace residue levels. To the best of our knowledge, this is the first example of high-performance MOFs trapping toxic cationic herbicides. PMID:26468513

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

    Science.gov (United States)

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

    2016-02-01

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

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

    CERN Document Server

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

    2014-01-01

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

  20. Effects of doping of metal cations on morphology, activity, and visible light response of photocatalysts

    International Nuclear Information System (INIS)

    Effects of doping of metal cations into wide band gap semiconductor photocatalysts on morphology, visible light response, and photocatalytic performance were studied. Doping of lanthanide and alkaline earth ions improved activity of a NaTaO3 photocatalyst for water splitting. Lanthanum was the most effective dopant. The NaTaO3:La with a NiO cocatalyst gave 56% of a quantum yield at 270 nm. This remarkable photocatalytic activity was brought by formations of nano-crystalline particle and surface nano-step structure by the doping. On the other hand, metal cation doping into ZnS, TiO2, and SrTiO3 gave visible light responses for H2 or O2 evolution from aqueous solutions containing of sacrificial reagents. The visible light responses were due to the electronic transition from donor levels formed with dopants to conduction bands of the host photocatalysts. Codoping was effective to compensate charge unbalance brought by doping of transition metal cations, resulting in the improvement of visible light response for photocatalytic reactions. Among the transition metal-doped photocatalysts, SrTiO3 doped with Rh (SrTiO3:Rh) was the novel metal oxide photocatalyst that produced H2 under visible light irradiation. The SrTiO3:Rh photocatalyst was employed with O2 evolution photocatalysts such as BiVO4 and WO3 for construction of Z-scheme systems that were active for water splitting into H2 and O2 under visible light irradiation

  1. Influence of "alternative" C-terminal amino acids on the formation of [b3 + 17 + Cat]+ products from metal cationized synthetic tetrapeptides.

    Science.gov (United States)

    Anbalagan, V; Silva, A T M; Rajagopalachary, S; Bulleigh, K; Talaty, E R; Van Stipdonk, M J

    2004-05-01

    The aim of this study was to investigate the dissociation patterns, and in particular the relative abundance of [b(3) + 17 + Cat](+), for peptides with C-termini designed to allow transfer of the -OH required to generate the product ion, but not necessarily as the most favored pathway. Working with the hypothesis that formation of a five-membered ring intermediate, including intramolecular nucleophilic attack by a carbonyl oxygen atom, is an important mechanistic step, several model peptides with general sequence AcFGGX were synthesized, metal cationized by electrospray ionization and subjected to collision-induced dissociation (CID). The amino acid at position X was one that either required a larger ring intermediate (beta-alanine, gamma-aminobutyric acid and epsilon-amino-n-caproic acid to generate six-, seven- or nine- membered rings, respectively) to transfer -OH, lacked a structural element required for nucleophilic attack (aminoethanol) or prohibited cyclization because of the inclusion of a rigid ring (p- and m-aminobenzoic acid). For Ag(+), Li(+) and Na(+) cationized peptides, our results show that amino acids requiring the adoption of larger ring intermediates suppressed the formation of [b(3) + 17 + Cat](+), while amino acids that prohibit cyclization eliminated the reaction pathway completely. Formation of [b(3) - 1 + Cat](+) from the alkali metal cationized versions was not a favorable process upon suppression or elimination of the [b(3) + 17 + Cat](+) pathway: the loss of H(2)O to form [M - H(2)O + Cat](+) was instead the dominant dissociation reaction observed. Multiple-stage dissociation experiments suggest that [M - H(2)O + Cat](+) is not [b(4) - 1 + Cat](+) arising from the loss of H(2)O from the C-terminus, but may instead be a species that forms via a mechanism involving the elimination of an oxygen atom from an amide group. PMID:15170745

  2. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Science.gov (United States)

    Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

    2013-08-13

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  3. Characterization of Alkali Metal Dispensers and Non-Evaporable Getter Pumps in Ultra-High Vacuum Systems for Cold Atomic Sensors

    OpenAIRE

    Scherer, David R.; Fenner, David B.; Hensley, Joel M.

    2012-01-01

    A glass ultrahigh vacuum chamber with rubidium alkali metal dispensers and non-evaporable getter pumps has been developed and used to create a cold atomic sample in a chamber that operates with only passive vacuum pumps. The ion-mass spectrum of evaporated gases from the alkali metal dispenser has been recorded as a function of dispenser current. The efficacy of the non-evaporable getter pumps in promoting and maintaining vacuum has been characterized by observation of the Rb vapor optical ab...

  4. Multi-physical model of cation and water transport in ionic polymer-metal composite sensors

    Science.gov (United States)

    Zhu, Zicai; Chang, Longfei; Horiuchi, Tetsuya; Takagi, Kentaro; Aabloo, Alvo; Asaka, Kinji

    2016-03-01

    Ion-migration based electrical potential widely exists not only in natural systems but also in ionic polymer materials. We presented a multi-physical model and investigated the transport process of cation and water of ionic polymer-metal composites based on our thorough understanding on the ionic sensing mechanisms in this paper. The whole transport process was depicted by transport equations concerning convection flux under the total pressure gradient, electrical migration by the built-in electrical field, and the inter-coupling effect between cation and water. With numerical analysis, the influence of critical material parameters, the elastic modulus Ewet, the hydraulic permeability coefficient K, the diffusion coefficient of cation dII and water dWW, and the drag coefficient of water ndW, on the distribution of cation and water was investigated. It was obtained how these parameters correlate to the voltage characteristics (both magnitude and response speed) under a step bending. Additionally, it was found that the effective relative dielectric constant ɛr has little influence on the voltage but is positively correlated to the current. With a series of optimized parameters, the predicted voltage agreed with the experimental results well, which validated our model. Based on our physical model, it was suggested that an ionic polymer sensor can benefit from a higher modulus Ewet, a higher coefficient K and a lower coefficient dII, and a higher constant ɛr.

  5. Release and sorption of alkali metals in coal fired combined cycle power systems; Freisetzung und Einbindung von Alkalimetallverbindungen in kohlebefeuerten Kombikraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael

    2009-07-01

    Coal fired combined cycle power systems will be a sufficient way to increase the efficiency of coal combustion. However, combined cycle power systems require a reliable hot gas cleanup. Especially alkali metals, such as sodium and potassium, can lead to hot corrosion of the gas turbine blading if they condensate as sulphates. The actual work deals with the release and sorption of alkali metals in coal fired combined cycle power systems. The influence of coal composition, temperature and pressure on the release of alkali species in coal combustion was investigated and the relevant release mechanisms identified. Alumosilicate sorbents have been found that reduce the alkali concentration in the hot flue gas of the Circulating Pressurized Fluidized Bed Combustion 2{sup nd} Generation (CPFBC 2{sup nd} Gen.) at 750 C to values sufficient for use in a gas turbine. Accordingly, alumosilicate sorbents working at 1400 C have been found for the Pressurized Pulverized Coal Combustion (PPCC). The sorption mechanisms have been identified. Thermodynamic calculations were performed to upscale the results of the laboratory experiments to conditions prevailing in power systems. According to these calculations, there is no risk of hot corrosion in both processes. Furthermore, thermodynamic calculations were performed to investigate the behaviour of alkali metals in an IGCC with integrated hot gas cleanup and H{sub 2} membrane for CO{sub 2} sequestration. (orig.)

  6. The effects of mono- and divalent metal cations on the solution structure of caffeine and theophylline

    Science.gov (United States)

    Nafisi, Shohreh; Monajemi, Majid; Ebrahimi, Saeedeh

    2004-11-01

    The interactions of caffeine and theophylline with potassium +, cobalt 2+ and nickel 2+ ions were studied in aqueous solution at physiological pH with constant ligand concentration and various metal ion contents. Fourier Transform infrared spectroscopy and absorption spectra were used to determine the cation binding mode and association constants. Spectroscopic results showed direct and indirect cation interactions for Co 2+, Ni 2+ and K + through O6 and N9 atoms (caffeine) and O6, N9 and N7 atoms (theophylline). The overall binding constants were, K(Co-caffeine)=6.92×10 4 M -1, K(Ni-caffeine)=2.22×10 4 M -1, K(K-caffeine)=5.08×10 3 M -1, K(Co-theophylline)=5.06×10 4 M -1, K(Ni-theophylline)=4.84×10 4 M -1 and K(K-theophylline)=2.13×10 3 M -1. The association constants showed weaker interaction for monovalent cation than divalent metal ions.

  7. Strategies to Suppress Cation Vacancies in Metal Oxide Alloys: Consequences for Solar Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Toroker, Maytal; Carter, Emily A.

    2015-09-01

    First-row transition metal oxides (TMOs) are promising alternative materials for inexpensive and efficient solar energy conversion. However, their conversion efficiency can be deleteriously affected by material imperfections, such as atomic vacancies. In this work, we provide examples showing that in some iron-containing TMOs, iron cation vacancy formation can be suppressed via alloying. We calculate within density functional theory+U theory the iron vacancy formation energy in binary rock-salt oxide alloys that contain iron, manganese, nickel, zinc, and/or magnesium. We demonstrate that formation of iron vacancies is less favorable if we choose to alloy iron(II) oxide with metals that cannot readily accept vacancy-generated holes, e.g., magnesium, manganese, nickel, or zinc. Since there are less available sites for holes and the holes are forced to reside on iron cations, the driving force for iron vacancy formation decreases. These results are consistent with an experiment observing a sharp drop in cation vacancy concentration upon alloying iron(II) oxide with manganese.

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

    Science.gov (United States)

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

    2016-06-01

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

  9. Degradation of functional group of cation exchange nuclear grade resin loaded with different metal ions due to gamma radiation exposure

    International Nuclear Information System (INIS)

    Ion exchange resins undergo degradation due to ionizing radiation while processing the radioactive water treatment. During this process, the cation resin used for this purpose gets loaded with various metal ions and presence of different metal ions in the resin may result into different degradation behaviors of functional group(s) (lowering the capacity). This work deals with the effect of few cations such as H+, Li+, Na+, Cs+ and Cu2+ on the degradation behavior of functional groups of strong acid cation resins exposed in different dose of 60Co gamma ray. Degradations were estimated by measuring the sulphate ion concentration in leach solution. (author)

  10. On-sun test results from second-generation and advanced-concepts alkali-metal pool-boiler receivers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.B.; Andraka, C.E.; Moss, T.A.; Cordeiro, P.G.; Dudley, V.E.; Rawlinson, K.S.

    1994-05-01

    Two 75-kW{sub t} alkali-metal pool-boiler solar receivers have been successfully tested at Sandia National Laboratories` National Solar Thermal Test Facility. The first one, Sandia`s `` second-generation pool-boiler receiver,`` was designed to address commercialization issues identified during post-test assessment of Sandia`s first-generation pool-boiler receiver. It was constructed from Haynes alloy 230 and contained the alkali-metal alloy NaK-78. The absorber`s wetted side had a brazed-on powder-metal coating to stabilize boiling. This receiver was evaluated for boiling stability, hot- and warm-restart behavior, and thermal efficiency. Boiling was stable under all conditions. All of the hot restarts were successful. Mild transient hot spots observed during some hot restarts were eliminated by the addition of 1/3 torr of xenon to the vapor space. All of the warm restarts were also successful. The heat-transfer crisis that damaged the first receiver did not recur. Thermal efficiency was 92.3% at 750{degrees}C with 69.6 kW{sub t} solar input. The second receiver tested, Sandia`s ``advanced-concepts receiver,`` was a replica of the first-generation receiver except that the cavities, which were electric-discharge-machined in the absorber for boiling stability, were eliminated. This step was motivated by bench-scale test results that showed that boiling stability improved with increased heated-surface area, tilt of the heated surface from vertical, and added xenon. The bench-scale results suggested that stable boiling might be possible without heated-surface modification in a 75-kW{sub t} receiver. Boiling in the advanced-concepts receiver with 1/3 torr of xenon added has been stable under all conditions, confirming the bench-scale tests.

  11. Changes in the Vibrational Spectra of Zeolites Due to Sorption of Heavy Metal Cations

    Science.gov (United States)

    Król, M.; Mozgawa, W.; Barczyk, K.; Bajda, T.; Kozanecki, M.

    2013-11-01

    This work presents the results of spectroscopic (MIR and Raman) studies of zeolite structures after immobilization of heavy metal cations from aqueous solutions. The sorption of Ag+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ ions has been conducted on zeolites belonging to different structural groups, i.e., sodium forms of natural chabazite, mordenite, ferrierite, and clinoptilolite, as well as on synthetic zeolite Y. Systematic changes in intensities and positions of the bands corresponding to the characteristic ring vibrations have been observed in the measured spectra. The most visible changes are observed in the FT-IR spectra of the samples in the range of 850-450 cm-1, and in the Raman spectra in the range of 600-250 cm-1. Depending on the zeolite structure, the bands, which can be regarded as a kind of indicator of ion exchange, were indentifi ed. For example, in the case of IR spectra, these bands are at 766, 703, 648, 578, and 506 cm-1 for zeolite Y, at 733 and 560 cm-1 for mordenite, at 675 cm-1 for clinoptilolite, etc. The degree of changes depends on both the type of cation and its concentration in the initial solution. This is connected with the way of binding of metal ions to the zeolite aluminosilicate framework, i.e., a proportion of the ion exchange and chemisorption in the process. Cations mainly undergoing ion exchange, such as Cd2+ or Pb2+, have the greatest impact on the character of the spectra. On the other hand, Cr3+ ions practically do not modify the spectra of zeolites. Results of IR and Raman spectroscopic studies have been compared with those obtained by atomic absorption spectroscopy (AAS), from which the proportion of ion exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated.

  12. Thermal and optical properties of Nd{sup 3+} doped lead zinc borate glasses—Influence of alkali metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Sasi Kumar, M.V.; Rajesh, D.; Balakrishna, A. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Ratnakaram, Y.C., E-mail: ratnakaramsvu@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2013-04-15

    In the present investigation a new series of six different Nd{sup 3+} doped alkali and mixed alkali (Li, Na, K, Li–Na, Li–K and Na–K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd–Ofelt (J–O) theory has been applied to calculate J–O intensity parameters, Ω{sub λ} (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (A{sub T}), branching ratios (β), radiative lifetimes (τ{sub R}) and integrated absorption cross-sections (Σ) were calculated using J–O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σ{sub P}) are obtained for all the observed emission transitions.

  13. Thermal and optical properties of Nd3+ doped lead zinc borate glasses—Influence of alkali metal ions

    Science.gov (United States)

    Sasi Kumar, M. V.; Rajesh, D.; Balakrishna, A.; Ratnakaram, Y. C.

    2013-04-01

    In the present investigation a new series of six different Nd3+ doped alkali and mixed alkali (Li, Na, K, Li-Na, Li-K and Na-K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd-Ofelt (J-O) theory has been applied to calculate J-O intensity parameters, Ωλ (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (AT), branching ratios (β), radiative lifetimes (τR) and integrated absorption cross-sections (Σ) were calculated using J-O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σP) are obtained for all the observed emission transitions.

  14. Thermal and optical properties of Nd3+ doped lead zinc borate glasses—Influence of alkali metal ions

    International Nuclear Information System (INIS)

    In the present investigation a new series of six different Nd3+ doped alkali and mixed alkali (Li, Na, K, Li–Na, Li–K and Na–K) heavy metal (PbO and ZnO) borate glasses were prepared using the melt quenching technique. The amorphous nature of the glass systems has been identified based on the X-ray diffraction analysis. The glass transition studies were carried out using differential scanning calorimetry (DSC). Optical properties were studied by measuring the optical absorption and near infrared luminescence spectra. The Judd–Ofelt (J–O) theory has been applied to calculate J–O intensity parameters, Ωλ (λ=2, 4 and 6) and in turn used to estimate radiative properties of certain transitions. Spectroscopic parameters such as transition probabilities (AT), branching ratios (β), radiative lifetimes (τR) and integrated absorption cross-sections (Σ) were calculated using J–O intensity parameters for all transitions. Using emission spectra, experimental branching ratios and stimulated emission cross-sections (σP) are obtained for all the observed emission transitions

  15. On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution.

    Science.gov (United States)

    Prelot, Benedicte; Ayed, Imen; Marchandeau, Franck; Zajac, Jerzy

    2014-01-01

    Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium. Compared to the retention limits of both resins under such idealized conditions, an important depression in the maximum adsorption capacity toward each main component was observed in multication systems. The overall effect of ion exchange process appeared to be an unpredictable outcome of the individual sorption capacities of the two resins toward various cations as a function of the cation charge, size, and concentration. The cesium retention capacity of the resins was diminished to about 25% of the "ideal" value in Effluent 1 and 50% in Effluent 2; a further decrease to about 15% was observed upon concomitant strontium addition. The uptake of strontium by the resins was found to be less sensitive to the addition of other metal components: the greatest decrease in the amount adsorbed was 60% of the ideal value in the two effluents for Amberlite® IRN77 and 75% for Amberlite™ IRN9652. It was therefore demonstrated that any performance tests carried out under idealized conditions should be exploited with much caution to predict the real performance of cation exchange resins under conditions of cation competition. PMID:24728575

  16. Hydration to the poly(oxyethylene) derivative complexes of alkali metal ions and barium ion in 1,2-dichloroethane

    International Nuclear Information System (INIS)

    A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, XH2O,S, and its complex, XH2O,comp, in water saturated with 1,2-DCE was determined by means of aquametry. The XH2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The XH2O,comp value decreases in the order Li+>Na+>K+≅Rb+≅Cs+ in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the XH2O,comp values of barium ion complexes are smaller than those of potassium ion complexes. (author)

  17. Viscometric and thermodynamic studies of interactions in ternary solutions containing sucrose and aqueous alkali metal halides at 293.15, 303.15 and 313.15 K

    Indian Academy of Sciences (India)

    Reena Gupta; Mukhtar Singh

    2005-05-01

    Viscosities and densities of sucrose in aqueous alkali metal halide solutions of different concentrations in the temperature range 293.15 to 313.15 K have been measured. Partial molar volumes at infinite dilution ($V_{2}^{0}$) of sucrose determined from apparent molar volume ($\\phi_v$) have been utilized to estimate partial molar volumes of transfer ($V^{0}_{2,tr}$) for sucrose from water to alkali metal halide solutions. The viscosity data of alkali metal halides in purely aqueous solutions and in the presence of sucrose at different temperatures (293.15, 303.15 and 313.5 K) have been analysed by the Jones-Dole equation. The nature and magnitude of solute-solvent and solute-solute interactions have been discussed in terms of the values of limiting apparent molar volume ($\\phi^{0}_{v}$), slope ($S_{v}$) and coefficients of the Jones-Dole equation. The structuremaking and structure-breaking capacities of alkali metal halides in pure aqueous solutions and in the presence of sucrose have been ascertained from temperature dependence of $\\phi^{0}_{v}$.

  18. A new route to the syntheses of alkali metal bis(fluorosulfuryl)imides: Crystal structure of LiN(SO2F)2

    Czech Academy of Sciences Publication Activity Database

    Beran, Martin; Příhoda, J.; Žák, Z.; Černík, M.

    2006-01-01

    Roč. 25, č. 6 (2006), s. 1292-1298. ISSN 0277-5387 Institutional research plan: CEZ:AV0Z40310501 Keywords : imido-bis( sulfuric acid ) difluoride * lithium bis(fluorosulfuryl)imide * alkali metal bis(fluorosulfuryl)imides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.843, year: 2006

  19. Structural and electronic engineering of 3DOM WO3 by alkali metal doping for improved NO2 sensing performance

    Science.gov (United States)

    Wang, Zhihua; Fan, Xiaoxiao; Han, Dongmei; Gu, Fubo

    2016-05-01

    Novel alkali metal doped 3DOM WO3 materials were prepared using a simple colloidal crystal template method. Raman, XRD, SEM, TEM, XPS, PL, Hall and UV-Vis techniques were used to characterize the structural and electronic properties of all the products, while the corresponding sensing performances targeting ppb level NO2 were determined at different working temperatures. For the overall goal of structural and electronic engineering, the co-effect of structural and electronic properties on the improved NO2 sensing performance of alkali metal doped 3DOM WO3 was studied. The test results showed that the gas sensing properties of 3DOM WO3/Li improved the most, with the fast response-recovery time and excellent selectivity. More importantly, the response of 3DOM WO3/Li to 500 ppb NO2 was up to 55 at room temperature (25 °C). The especially high response to ppb level NO2 at room temperature (25 °C) in this work has a very important practical significance. The best sensing performance of 3DOM WO3/Li could be ascribed to the most structure defects and the highest carrier mobility. And the possible gas sensing mechanism based on the model of the depletion layer was proposed to demonstrate that both structural and electronic properties are responsible for the NO2 sensing behavior.Novel alkali metal doped 3DOM WO3 materials were prepared using a simple colloidal crystal template method. Raman, XRD, SEM, TEM, XPS, PL, Hall and UV-Vis techniques were used to characterize the structural and electronic properties of all the products, while the corresponding sensing performances targeting ppb level NO2 were determined at different working temperatures. For the overall goal of structural and electronic engineering, the co-effect of structural and electronic properties on the improved NO2 sensing performance of alkali metal doped 3DOM WO3 was studied. The test results showed that the gas sensing properties of 3DOM WO3/Li improved the most, with the fast response-recovery time and

  20. Heavy main-group iodometallates hybridized by alkali metal via 1,10-Phenanthroline-5,6-dione

    Indian Academy of Sciences (India)

    Mengfan Yin; Gengxing Cai; Peng Wang; Xihui Chao; Jibo Liu; Haohong Li; Zhirong Chen

    2015-09-01

    Alkali metals were introduced into heavy main-group iodometallates to get two new IA/IVAheterometallic frameworks [PbI3K(pdon)(H2O)2] (1) and {[Pb3I9K2(pdon)2(H3O)]·H2O} (2) (pdon=1,10-phenanthroline-5,6-dione), which were obtained as single phases by hydrothermal method at different pH values. Compounds 1 and 2 are three-dimensional heterometallic frameworks constructed from the linkage of pdon ligand between iodometallate chains and potassium oxides/iodide clusters. Specially, these two heterometallic frameworks exhibit broadened absorption bands at 700 and 750 nm compared with those of bulk PbI2 and pdon ligand. The band gap of 2 is wider than that of 1, which is due to the absence of · · · interaction in 2. Their thermal stabilities are also discussed.

  1. A stochastic optimization method based technique for finding out reaction paths in noble gas clusters perturbed by alkali metal ions

    International Nuclear Information System (INIS)

    Graphical abstract: The structure of a minimum in Ar19K+ cluster. Abstract: In this paper we explore the possibility of using stochastic optimizers, namely simulated annealing (SA) in locating critical points (global minima, local minima and first order saddle points) in Argon noble gas clusters perturbed by alkali metal ions namely sodium and potassium. The atomic interaction potential is the Lennard Jones potential. We also try to see if a continuous transformation in geometry during the search process can lead to a realization of a kind of minimum energy path (MEP) for transformation from one minimum geometry to another through a transition state (first order saddle point). We try our recipe for three sizes of clusters, namely (Ar)16M+, (Ar)19M+ and (Ar)24M+, where M+ is Na+ and K+.

  2. Thermally stimulated luminescence and lattice defects in crystals of alkali metal borate LiB3O5 (LBO)

    International Nuclear Information System (INIS)

    The recombination processes and lattice defects in crystals of alkali metal borate LiB3O5 (LBO) were studied by the means of the thermally stimulated luminescence (TL) and electron spin resonance (ESR) techniques. The glow curves, the spectra of the LBO recombination luminescence, and the angular variations of ESR-spectra of the O- center in three different planes were measured in the temperature range from 80 to 400 K. The luminescence bands were assigned to the electron (Em=4.0 eV) and hole (Em=4.2 eV) recombination processes. The model of the trapped hole center O- was proposed. The processes responsible for the formation of localised electronic excitations in LBO were discussed and compared with those taking place in other wide-gap oxides

  3. Synthesis and X-ray Characterization of Alkali Metal 2-Acyl-1,1,3,3-tetracyanopropenides.

    Science.gov (United States)

    Karpov, Sergey V; Grigor'ev, Arthur A; Kayukov, Yakov S; Karpova, Irina V; Nasakin, Oleg E; Tafeenko, Victor A

    2016-08-01

    A novel route for synthesis of 2-acyl-1,1,3,3-tetracyanopropenides (ATCN) salts in high yields and excellent purities starting from readily available methyl ketones, malononitrile, bromine, and alkali metal acetates is reported. The starting aryl(heteroaryl) methyl ketones were oxidized to the corresponding α-ketoaldehydes by new a DMSO-NaBr-H2SO4 oxidation system in yields up to 90% within a short reaction time of 8-10 min. The subsequent stages of ATCN preparation are realized in aqueous media without use of any toxic solvents, in accordance with principle 5 of "green chemistry". Lithium, sodium, potassium, rubidium, and cesium 2-benzoyl-1,1,3,3-tetracyanopropenides were characterized by X-ray diffraction analysis. These salts show a good potential for synthesis of five- and six-membered heterocycles and may serve as potentially useful ligands in coordination and supramolecular chemistry. PMID:27384963

  4. A review of modelling the interaction between natural organic matter and metal cations

    International Nuclear Information System (INIS)

    This report reviews techniques available to model the interaction between natural organic matter (mainly fulvic and humic acids) and metal cations and protons. A comprehensive overview over the properties of natural organic matter is given and experimental techniques are presented briefly. Two major concepts of modelling have been identified: discrete ligand models and continuous distribution model. Different modelling approaches like Discrete Ligand Models (s.s.), Random-Structure Model, Affinity Spectra, Statistical Distribution Models, Continuous Stability Function Models and surface sorption models and their advantages/disadvantages are discussed. (author)

  5. Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4.

    Directory of Open Access Journals (Sweden)

    Sonica Sondhi

    Full Text Available A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

  6. A series of new phases in the alkali metal-Nb(V)/Ta(V)-Se(IV)/Te(IV)-O systems.

    Science.gov (United States)

    Gu, Qian-Hua; Hu, Chun-Li; Zhang, Jian-Han; Mao, Jiang-Gao

    2011-03-21

    Six new phases in the alkali metal-Nb(V)/Ta(V)-Se(IV)/Te(IV)-O systems have been prepared by solid-state reactions at high-temperatures. Their structures were determined by single-crystal X-ray diffraction studies. AM(3)O(6)(QO(3))(2) (A = K, Rb, M = Nb, Ta, Q = Te; A = K, M = Nb, Q = Se) are isomorphous and their structures feature a 3D network with 1D 4- and 6-MRs tunnels along the a-axis which is composed of 2D layers of corner-sharing MO(6) octahedra bridged by QO(3) groups. The alkali metal ions are located at the above 1D tunnels of 6-MRs. The structure of Cs(3)Nb(9)O(18)(TeO(3))(2)(TeO(4))(2) features a thick Nb-Te-O layer built of corner-sharing NbO(6) octahedra, TeO(3) and TeO(4) groups. The 2D layer of the NbO(6) octahedra with 1D tunnels of 6-MRs along the c-axis are formed by 1D chains of NbO(6) chains along the c-axis and linear Nb(4)O(21) tetramers by corner-sharing. The TeO(3) and TeO(4) groups are grafted on both sides of the niobium-oxide layer via Nb-O-Te or/and Te-O-Te bridges. The caesium(i) ions are located at the above 1D tunnels of 6-MRs. TGA, UV-vis and infrared spectral measurements as well as electronic structure calculations have also been performed. PMID:21293821

  7. Development of operationally stable inverted organic light-emitting diode prepared without using alkali metals (Presentation Recording)

    Science.gov (United States)

    Fukagawa, Hirohiko; Morii, Katsuyuki; Hasegawa, Munehiro; Gouda, Shun; Tsuzuki, Toshimitsu; Shimizu, Takahisa; Yamamoto, Toshihiro

    2015-10-01

    The OLED is one of the key devices for realizing future flexible displays and lightings. One of the biggest challenges left for the OLED fabricated on a flexible substrate is the improvement of its resistance to oxygen and moisture. A high barrier layer [a water vapor transmission rate (WVTR) of about 10-6 g/m2/day] is proposed to be necessary for the encapsulation of conventional OLEDs. Some flexible high barrier layers have recently been demonstrated; however, such high barrier layers require a complex process, which makes flexible OLEDs expensive. If an OLED is prepared without using air-sensitive materials such as alkali metals, no stringent encapsulation is necessary for such an OLED. In this presentation, we will discuss our continuing efforts to develop an inverted OLED (iOLED) prepared without using alkali metals. iOLEDs with a bottom cathode are considered to be effective for realizing air-stable OLEDs since the electron injection layer (EIL) can be prepared by fabrication processes that might damage the organic layers, resulting in the enhanced range of materials suitable for EILs. We have demonstrated that a highly efficient and relatively air-stable iOLED can be realized by employing poly(ethyleneimine) as an EIL. Dark spot formation was not observed after 250 days in the poly(ethyleneimine)-based iOLED encapsulated by a barrier film with a WVTR of 10-4 g/m2/day. In addition, we have demonstrated the fabrication of a highly operational stable iOLED utilizing a newly developed EIL. The iOLED exhibits an expected half-lifetime of over 10,000 h from an initial luminance of 1,000 cd/m2.

  8. Two uranyl-organic frameworks with pyridinecarboxylate ligands. A novel hetero-metallic uranyl-copper(II) complex with a cation-cation interaction

    International Nuclear Information System (INIS)

    Reaction of uranyl nitrate with pyridine-2-carboxylic acid (HL1) under hydrothermal conditions gives the complex [(UO2)3(L1)4(NO3)2], 1, which differs from the previously reported molecular complex, obtained at room temperature, by the absence of water, coordinated and free, and the extended carboxylate bridging. Although the tri-metallic basic unit is similar in both cases, 1 crystallizes as a two-dimensional assembly. A hetero-metallic complex results from the reaction of uranyl nitrate and copper(II) trifluoromethanesulfonate with nicotinic acid (pyridine-3-carboxylic acid, HL2), [UO2Cu(L2)2(NO3)2], 2, in which copper nicotinate two-dimensional subunits are bridged by uranyl nitrate groups to give a three-dimensional framework. The copper atom environment geometry is elongated octahedral. with one of the axial donors being a uranyl oxo group (cation-cation interaction). (author)

  9. Phase behaviour and thermodynamics of poly(1,4-phenylene ether sulphone) and poly(ethylene oxide)/alkali-metal salt complex blends: a thermal analysis study

    Energy Technology Data Exchange (ETDEWEB)

    Jin, J. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE113TU (United Kingdom); Song, M. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE113TU (United Kingdom)]. E-mail: m.song@lboro.ac.uk

    2005-02-01

    The phase behaviour and thermodynamics of poly(1,4-phenylene ether sulfone) (PES) and poly(ethylene oxide) (PEO)/alkali-metal salt complex blends were investigated by means of differential scanning calorimetry (DSC) and modulated DSC (MDSC). Experimental results show that the blend systems remain miscible after incorporating various alkali-metal salts: CF{sub 3}SO{sub 3}Li, CF{sub 3}SO{sub 3}Na and CF{sub 3}SO{sub 3}K. The cloud point temperature strongly depended on the Li (Na or K)/O ratio in the PES-PEO/alkali-metal salt complex blends. With increasing the Li{sup +} (Na{sup +} or K{sup +})/O ratio, the phase diagram of the PES-PEO/alkali-metal salt complex blends tended to be symmetrical. When Li{sup +}/O = 0.02, the lower critical solution temperature (LCST) of the PES-PEO/CF{sub 3}SO{sub 3}Li complex blends was located at the 30/70 PES/PEO composition. The mixing enthalpy decreased in the PES-PEO/alkali-metal salt complex blends with increasing Li{sup +} (Na{sup +} or K{sup +})/O ratio. The radius of ion has significant influence on the phase behaviour of PES/PEO blends. MDSC results showed that the change of heat capacity at the temperature of the binodal phase separation is similar to that of a melt transition in semi-crystalline polymers, which confirms the mechanism of binodal phase separation: nucleation and growth.

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

    Science.gov (United States)

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

    2015-09-01

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

  11. Molecular-orbital theory for the stopping power of atoms in the low velocity regime:the case of helium in alkali metals

    OpenAIRE

    Dorado, Jose J.; Flores, F.

    1993-01-01

    A free-parameter linear-combination-of-atomic-orbitals approach is presented for analyzing the stopping power of slow ions moving in a metal. The method is applied to the case of He moving in alkali metals. Mean stopping powers for He present a good agreement with local-density-approximation calculations. Our results show important variations in the stopping power of channeled atoms with respect to their mean values.

  12. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations.

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E

    2006-02-01

    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  13. Electrochemical catalytic treatment of wastewater by metal ion supported on cation exchange resin

    International Nuclear Information System (INIS)

    The electrochemical oxidation of phenol in synthetic wastewater and paper mill wastewater catalyzed by metal ion supported on cation exchange resin in suspended bed electrolytic reactor with graphite electrode has been investigated. The catalyst was characterized by SEM and XPS spectra and the effects of pH, the different metal ion and NaCl on the efficiency of the electrochemical oxidation phenol process were also studied. It was found that the catalyst containing Fe3+ had the highest electrochemical catalytic activity for the electrochemical oxidation of phenol. When the initial concentration of phenol was 200 ppm, up to 90% chemical oxygen demand (COD) removal was obtained in 10 min. When the catalyst containing Fe3+ was used to the paper mill wastewater, it still showed high efficiency. The COD removal could get to 75% in 60 min

  14. Local structure of alkalis in mixed-alkali borate glass to elucidate the origin of mixed-alkali effect

    Directory of Open Access Journals (Sweden)

    Yomei Tokuda

    2015-12-01

    Full Text Available We report the structural analysis of Na+ and Cs+ in sodium cesium borate crystals and glasses using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR spectroscopy. The composition dependence of NMR spectra of the borate was similar to that of the silicate: (1 the peak position of cesium borate crystals shifted to upfield for structures with larger Cs+ coordination numbers, (2 the MAS NMR spectra of xNa2O-yCs2O-3B2O3 (x = 0, 0.25, 0.5, 0.75, 1.0, x + y = 1 glass showed that the average coordination number (CN of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+ ratio. However, the degree of decrement in borates is much smaller than that in silicates. We have considered that the small difference in CN is due to 4-coordinated B, because it is electrically compensated by the alkali metal ions resulting in the restriction of having various coordinations of O to alkali metal.

  15. Application of X-ray diffraction technique for determining triclinicity of alkali-feldspar from the rare metal pegmatites of the Pandikimal Area, North Orissa, India

    International Nuclear Information System (INIS)

    The zoned rare metal pegmatites of Archaean age in the Jharsuguda district of north Orissa, eastern India, are well-known for their potentiality for Nb, Ta, and Be minerals. They also contain limited Li, Bi, Th, and U minerals. Because of the economic concentrations of the ore minerals of Nb-Ta and Be, they are being mined for recovering columbite-tantalite and beryl. In this paper, the values of triclinicity of alkali-feldspars, determined by X-ray diffraction, are presented and, based on the same data, the evolutionary history of the rare metal pegmatites is traced. The values of triclinicity range from 0.83 to 0.97 with an average of 0.92. The high values of triclinicity suggest that the investigated alkali-feldspars from the rare metal pegmatites of the Pandikimal area belong to the category of maximum microcline. It would, thus, mean that during the crystallisation of alkali-feldspar, and by implication their host rare metal pegmatites, not only was the rate of cooling slow, the temperature of crystallisation was also falling. Accordingly, it is interpreted that the rare metal pegmatites of the Pandikimal area crystallised slowly under a falling-temperature regime in deep-seated plutonic conditions. The presence of large beryl crystals in the rare metal pegmatites also supports this interpretation. (author)

  16. A review of modelling the interaction between natural organic matter and metal cations

    International Nuclear Information System (INIS)

    This report reviews techniques available to model the interaction between natural organic matter (mainly fulvic and humic acids) and protons and metal cations. A concise definition of natural organic matter is given and their properties are outlined. These materials are macromolecules which exhibit a polyelectrolyte character owing to numerous dissociable functional groups which are attached to their carbon backbone or from integral parts of the structure. The polyelectrolyte character is thought to be responsible for their conformation, hydrogen bonding or bridging by metal cations between subunits being important mechanisms. Environmental parameters like pH and ionic strength thus will have profound effects on the conformation of natural organic matter, the properties of which can change from being a flexible polymer to being a rigid gel. Binding mechanisms and binding strengh are discussed and an overview of relevant techniques of investigation is given. This work is part of the Commission's Mirage project - Phase 2, research area Geochemistry of actinides and fission products in natural aquifer systems

  17. Investigation into the modes of action of extractants for base metal cations and metalate anions

    OpenAIRE

    Turkington, Jennifer Rachel

    2013-01-01

    This thesis involves the design and development of reagents for the recovery of base metals (specifically zinc, nickel and cobalt) in hydrometallurgical solvent extraction processes. The work aims to demonstrate how ligand design can affectively tune the strength and selectivity of extractants to achieve efficient recovery of the desired base metals. Chapter 1 reviews current solvent extraction processes used in extractive metallurgy, encompassing both the well established tech...

  18. Use of ionic model for analysis of intramolecular movement in alkali metal metaborate molecules

    International Nuclear Information System (INIS)

    To clear out the peculiarities of intramolecular movement in MBO2 (where M=Li, Na, K, Rb, Cs) molecules the energy dependence of cation electrostatic interaction with BO2 anion on the charge value of oxygen, values of the MOB valence angle and internuclear distance r(M-O) is calculated. The calculation results on the base of ionic model show that the minimum of potential energy function corresponds to angular configuration of the MBO2 molecules. Parameters of potential function of deformation oscillation connected with the change of MOB angle, are evaluated

  19. Host--guest complexation. 15. Macrocyclic acetylacetone ligands for metal cations

    International Nuclear Information System (INIS)

    Five macrocycles containing 1,5-disubstituted acetylacetone units (AcAc) have been synthesized. Their abilities to complex metal cations in water--dioxane have been compared to those of noncyclic model compounds. The AcAc units were bound together through bridges composed of the following groups: oxa (O), ethylene (E), and 1,3-disubstituted benzene (B). Cycles O(AcAcOEOE)(EOEOE)O(7), (OEOAcAcOE)2 (8), and (OEOAcAcOE)3 (9) were prepared by hydrolysis of rings closed by the reactions of CH2[HOCH2C(SCH2)2CH2]2 (2) and appropriate polyethylene glycol ditosylates. Ligand systems O(EAcAcE)2O (12) and B(CH2AcAcCH2)2B (14) were synthesized in Ca2+ or Mg2+ templated, two-step sequences involving reactions of HAcAcH dianions with either diethylene glycol ditosylate of m-xylyl dibromide, respectively. The preparation of (CH2IsCH2O)3 (17) is also described, in which Is is the 3,5-disubstituted isoxazole unit. Also described are the preparations of O(EAcAcH)2 (11), B(CH2AcAcH)2 (13), and P(CH2AcAcH)2 (15), in which P is 2,6-disubstituted pyridine. The logarithms of the formation constants (log K/sup f//sub av/) of the salts of (OEOAcAcOE)2 with 11 divalent metal cations and of (OEOAcAcOE)3 with 3 trivalent cations were 1.8 to 6.3 units higher valued than for CH3OAcAcOCH3. The log K/sup f//sub av/values for salt formation of O(EAcAcE)2O and B(CH2AcAcCH2)2B with 10 divalent cations were compared with those of O(EAcAcH)2 and B(CH2AcAcH)2, respectively, and with HAcAcH itself. Without exception, O(EAcAcE)2O > O(EAcAcH)2 > HAcAcH in values of log k/sup f//sub av/, the maximum difference being 4.3 for Ca2+

  20. Development of Comparative Toxicity Potentials of 14 cationic metals in freshwater.

    Science.gov (United States)

    Dong, Yan; Gandhi, Nilima; Hauschild, Michael Z

    2014-10-01

    Site-dependent and site-generic Comparative Toxicity Potentials (CTPs) (also known as Characterization Factors (CFs)) were calculated for 14 cationic metals (Al(III), Ba, Be, Cd, Co, Cr(III), Cs, Cu(II), Fe(II), Fe(III), Mn(II), Ni, Pb, Sr and Zn), to be applied in Life Cycle Impact Assessment. CTPs were calculated for 7 EU-archetypes, taking bioavailability and speciation pattern into account. The resulting site-dependent CTPs showed up to 2.4-6.5 orders of magnitude variation across archetypes for those metals that form stable hydroxyl compounds in slightly alkaline waters (Al(III), Be, Cr(III), Cu(II) and Fe(III)), emphasizing the importance of using site-dependent CTPs for these metals where possible. For the other metals, CTPs stayed within around 0.9 orders of magnitude, making spatial differentiation less important. In acidic waters (pHarchetype CTPs was recommended as site-generic CTP for use in LCA studies, where receiving location is unclear. Compared to previous studies by Gandhi et al. (2010, 2011a), new site-dependent CTPs were similar or slightly higher for Cd, Co, Ni, Pb and Zn, but 1-2 orders of magnitude higher for Cu. Compared to the default site-generic CTPs in the frequently used characterization models USES-LCA and USEtox, new site-generic CTPs were mostly higher or similar, within up to ∼2 orders of magnitude difference. PMID:25048884

  1. Development of Comparative Toxicity Potentials of 14 cationic metals in freshwater

    DEFF Research Database (Denmark)

    Dong, Yan; Gandhi, Nilima; Hauschild, Michael Zwicky

    2014-01-01

    . CTPs were calculated for 7 EUarchetypes, taking bioavailability and speciation pattern into account. The resulting site-dependent CTPs showed up to 2.4–6.5 orders of magnitude variation across archetypes for those metals that form stable hydroxyl compounds in slightly alkaline waters (Al(III), Be, Cr......Site-dependent and site-generic Comparative Toxicity Potentials (CTPs) (also known as Characterization Factors (CFs)) were calculated for 14 cationic metals (Al(III), Ba, Be, Cd, Co, Cr(III), Cs, Cu(II), Fe(II), Fe(III), Mn(II), Ni, Pb, Sr and Zn), to be applied in Life Cycle Impact Assessment......(III), Cu(II) and Fe(III)), emphasizing the importance of using site-dependent CTPs for these metals where possible. For the other metals, CTPs stayed within around 0.9 orders of magnitude, making spatial differentiation less important. In acidic waters (pH < 6.4), Al(III) and Cu(II) had the highest CTPs...

  2. Organometallic Probe for the Electronics of Base-Stabilized Group 11 Metal Cations.

    Science.gov (United States)

    Braunschweig, Holger; Ewing, William C; Kramer, Thomas; Mattock, James D; Vargas, Alfredo; Werner, Christine

    2015-08-24

    A number of trimetalloborides have been synthesized through the reactions of base-stabilized coinage metal chlorides with a dimanganaborylene lithium salt in the hope of using this organometallic platform to compare and evaluate the electronics of these popular coinage metal fragments. The adducts of Cu(I), Ag(I), and Au(I) ions, stabilized by tricyclohexylphosphine (PCy3), N-1,3-bis(4-methylphenyl)imidazol-2-ylidene (ITol), or 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene (CAAC), with [{Cp(CO)2Mn}2B](-) were studied spectroscopically, structurally, and computationally. The geometries of the adducts fall into two classes, one symmetric and one asymmetric, each relying on the combined characteristics of both the metal and ligand. The energetic factors proposed as the causes of the structural differences were investigated by ETS-NOCV (extended transition state-natural orbitals for chemical valence) analysis, which showed the final geometry to be controlled by the competition between the tendency of the coinage metal to adopt a higher or lower coordination number and the willingness of the cationic fragment to participate in back-bonding interactions. PMID:26178571

  3. Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

    International Nuclear Information System (INIS)

    Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-napthyl-phenyl)-1.1′-biphenyl-4.4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq3 layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: ► Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. ► Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. ► The Improved OLED performance was attributed to the possible interfacial chemical reaction. ► Electron-only devices are fabricated to demonstrate the electron injection enhancement.

  4. Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

    Energy Technology Data Exchange (ETDEWEB)

    Zou Ye [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Deng Zhenbo, E-mail: zbdeng@bjtu.edu.cn [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Xu Denghui [Department of Mathematics and Physics, Beijing Technology and Business University, Beijing 100037 (China); Lue Zhaoyue; Yin Yuehong; Du Hailiang; Chen Zheng; Wang Yongsheng [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2012-02-15

    Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N Prime -diphenyl-N,N Prime -bis(1-napthyl-phenyl)-1.1 Prime -biphenyl-4.4 Prime -diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq{sub 3})/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq{sub 3} layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: Black-Right-Pointing-Pointer Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. Black-Right-Pointing-Pointer Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. Black-Right-Pointing-Pointer The Improved OLED performance was attributed to the possible interfacial chemical reaction. Black-Right-Pointing-Pointer Electron-only devices are fabricated to demonstrate the electron injection enhancement.

  5. The electronic properties of bare and alkali metal adsorbed two-dimensional GeSi alloy sheet

    Science.gov (United States)

    Qiu, Wenhao; Ye, Han; Yu, Zhongyuan; Liu, Yumin

    2016-09-01

    In this paper, the structural and electronic properties of both bare and alkali metal (AM) atoms adsorbed two-dimensional GeSi alloy sheet (GeSiAS) are investigated by means of first-principles calculations. The band gaps of bare GeSiAS are shown slightly opened at Dirac point with the energy dispersion remain linear due to the spin-orbit coupling effect at all concentrations of Ge atoms. For metal adsorption, AM atoms (including Li, Na and K) prefer to occupy the hexagonal hollow site of GeSiAS and the primary chemical bond between AM adatom and GeSiAS is ionic. The adsorption energy has an increase tendency with the increase of the Ge concentration in supercell. Besides, single-side adsorption of AM atoms introduces band gap at Dirac point, which can be tuned by the Ge concentration and the species of AM atoms. The strong relation between the band gaps and the distribution of Si and Ge atoms inside GeSiAS are also demonstrated. The opened band gaps of AM covered GeSiAS range from 14.8 to 269.1 meV along with the effective masses of electrons ranging from 0.013 to 0.109 me, indicating the high tunability of band gap as well as high mobility of carriers. These results provide a development in two-dimensional alloys and show potential applications in novel micro/nano-electronic devices.

  6. Fluorescent heavy metal cation sensing with water dispersible 2MPA capped CdSe/ZnS quantum dots

    International Nuclear Information System (INIS)

    Here we report the fluorescence response of water dispersible CdSe/ZnS core–shell quantum dots capped with 2-mercaptopropionic acid (2MPA) towards different concentrations of heavy metal cations, namely mercury, lead and cadmium. Upon exposure to different concentrations of the various metal cations, a concentration-dependent decrease in the QDs’ fluorescence emission was observed, which was decaying exponential in nature. The greatest degree of quenching was achieved in the presence of mercury. The resultant quantum dots were subsequently characterised by UV–vis spectroscopy, photo-luminescent spectroscopy, Raman Spectroscopy and X-ray diffraction. The quantitative detection of mercury, lead and cadmium cations by these capped quantum dots makes them exciting candidates for heavy metal sensing applications

  7. Fluorescent heavy metal cation sensing with water dispersible 2MPA capped CdSe/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, D., E-mail: vasudevand@rediffmail.com [Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India); Trinchi, Adrian; Hardin, Simon G.; Cole, Ivan S. [CSIRO Materials Science and Engineering, Private Bag 33, Clayton South MDC 3169 (Australia)

    2015-10-15

    Here we report the fluorescence response of water dispersible CdSe/ZnS core–shell quantum dots capped with 2-mercaptopropionic acid (2MPA) towards different concentrations of heavy metal cations, namely mercury, lead and cadmium. Upon exposure to different concentrations of the various metal cations, a concentration-dependent decrease in the QDs’ fluorescence emission was observed, which was decaying exponential in nature. The greatest degree of quenching was achieved in the presence of mercury. The resultant quantum dots were subsequently characterised by UV–vis spectroscopy, photo-luminescent spectroscopy, Raman Spectroscopy and X-ray diffraction. The quantitative detection of mercury, lead and cadmium cations by these capped quantum dots makes them exciting candidates for heavy metal sensing applications.

  8. Atomic many-body effects and Lamb shifts in alkali metals

    CERN Document Server

    Ginges, J S M

    2016-01-01

    We present a detailed study of the Flambaum-Ginges radiative potential method which enables the accurate inclusion of quantum electrodynamics (QED) radiative corrections in a simple manner in atoms, ions, and molecules over the range 10<=Z<=120, where Z is the nuclear charge. Calculations are performed for binding energy shifts to the lowest valence s, p, and d waves over the series of alkali atoms Na to E119. The high accuracy of the radiative potential method is demonstrated by comparison with rigorous QED calculations in frozen atomic potentials, with deviations on the level of 1%. The many-body effects of core relaxation and second- and higher-order perturbation theory on the interaction of the valence electron with the core are calculated. The inclusion of many-body effects tends to increase the size of the shifts, with the enhancement particularly significant for d waves; for K to E119, the self-energy shifts for d waves are only an order of magnitude smaller than the s-wave shifts. It is shown th...

  9. The role of multivalent metal cations and organic complexing agents in bitumen-mineral interactions in aqueous solutions

    Science.gov (United States)

    Gan, Weibing

    A systematic investigation was carried out to study the interactions between bitumen (or hexadecane) and minerals (quartz, kaolinite and illite) in aqueous solutions containing multivalent metal cations Ca2+, Mg2+ and Fe2+/Fe3+, in the absence and presence of organic complexing agents (oxalic acid, EDTA and citric acid). A range of experimental techniques, including coagulation measurement, visualization of bitumen-mineral attachment, metal ion adsorption measurement, zeta potential measurement, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopic analyses, were employed in the investigation. Free energy changes of adsorption of metal cations on the minerals and bitumen were evaluated using the James & Healy thermodynamic model. Total interaction energies between the minerals and bitumen were calculated using classical DLVO theory. It was observed that while the tested minerals showed varying degrees of mutual-coagulation with bitumen (or hexadecane), the presence of the multivalent metal cations could prominently increase the mutual coagulation. It was also found that such enhancement of the mutual coagulation was only significant when the metal cations formed first-order hydroxyl complexes (such as CaOH +, MgOH+, etc.) or metal hydroxides (such as Fe(OH) 3, Mg(OH)2, etc.). Therefore, the increase of the bitumen-mineral mutual coagulation by the metal cations was strongly pH dependent. Organic complexing agents (oxalic acid, citric acid and EDTA) used in this study, citric acid in particular, significantly reduced or virtually eliminated the mutual coagulation between bitumen (or hexadecane) and minerals caused by metal cations Ca2+, Mg2+, Fe 2+ and Fe3+. Due to its ability to substantially lower the mutual coagulation between bitumen and mineral particles, citric acid was found the most effective in improving bitumen-mineral liberation in solutions containing the multivalent metal cations at pH 8--10. In small scale flotation experiments

  10. Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ya-Fen [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China); Chen, Hua-Wei [Department of Cosmetic Application and Management, St. Mary' s Medicine Nursing and Management College, I-Lan, Taiwan (China); Chien, Poh-Sun [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Chiou, Chyow-San, E-mail: cschiou@niu.edu.tw [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Liu, Cheng-Chung [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China)

    2011-01-30

    A magnetic adsorbent, amine-functionalized silica magnetite (NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4}), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g{sup -1} for copper ions and of 217 mg g{sup -1} for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol{sup -1} and 12.06 kJ mol{sup -1}, respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were provided by a solution with 0.1 M HNO{sub 3} for copper ions and with 0.05 M NaOH for RB5.

  11. Kinetics and thermodynamics of sorption of alkali metals ions with tin phosphate

    International Nuclear Information System (INIS)

    In order to extract microquantities of potassium from sodium iodide the sorption method with application of tin phosphate as ion exchanger is proposed. The conditions of synthesis of tin phosphate are optimized. Theoretical aspects of sorption process are considered. The kinetics of sorption of alkaline metals with amorphous tin phosphate is studied by means of limited volume method. The activation energies of sorption of alkaline metals ions are defined. Thermodynamic characteristics of process are defined as well.

  12. Exchange reactions in the systems of alkali metal, silver and thallium, sulfates, niobates and tantalates

    International Nuclear Information System (INIS)

    Investigated are exchange interactions in diagonal cross sections of twenty triple mutual systems with A and A' cations and SO4 and MO3 anions where A and A'-Li, Na, K, Ag, Tl, M-Nb, Ta using the methods of X-ray phase, chemical and differential thermal analyses. Exchange reaction between crystal complex oxide and melted salt are effective synthesis method. These reactions in particular permitted to obtain pure AgNbO3, AgTaO3 and their solid solutions at temperatures hundreds degrees lower than in displacement reactions. Equilibrium samples of AMO3-A'MO3 systems, continuous or discontinuous solid solutions, compounds (except NaMO3-KMO3, and also LiTaO3-KTaO3) are formed in exchange reactions when there is sulfate shortage. Thus, exchange reactions can be applied for solid solution synthesis, and also for phase diagram study

  13. IR spectra and structure of di-2-ethylhexyl phosphates of alkali and alkaline earth metals

    International Nuclear Information System (INIS)

    Using the method of IR spectroscopy (25-4000 cm-1) types of di-2-ethylhexylphosphate-anion (X-) coordination to M+ (M = Li, Na, K, Rb, Cs) and Mg2+ have been studied in solid salts and their solutions in CCl4. Analysis of IR spectra has shown that CsX in the CCl4 medium and in the solid phase exists practically only as one compound and it contains two nonequivalent bonds: M-O and M...O, i. e. the POO - group in CsX is bidentate. Besides, a small part of the CsX molecules (+ cation coordination type variation in the series from Li+ to Cs+ are discussed in connection with changes in the M+ charge density and radii. The properties of the salts and corresponding carboxylates studied are compared

  14. Release and transformation of alkali metals during co-combustion of coal and sulfur-rich wheat straw

    International Nuclear Information System (INIS)

    Highlights: • Wheat straw rich in sulfur compared to coal was chosen as biomass material. • The behavior of alkali metal species during co-combustion was investigated. • The amount of KCl(g) and NaCl(g) was decreased by adding coal to wheat straw. • Most of fuel K was retained in the bottom ash as K2SO4, KAlSiO4 and KAlSiO6. • The amount of K2SO4 in the bottom ash decreased with temperature increase. - Abstract: Co-combustion of coal and biomass is a low-cost, large-scale, and efficient way to utilize biomass energy, which has a wide range of potential applications. However, biomass, especially herbaceous fuels, contains high levels of volatile K, Na, and Cl, the use of which may result in ash-related operational problems, such as corrosion, fouling, and slagging during thermal utilization. The aim of this study is to investigate the effects of wheat straw and temperature on the release and transformation of alkali metal species during co-combustion of coal and S-rich wheat straw. Results indicate that the amounts of K and Na released during co-combustion could be reduced by the effects of Fe, Ti, S, Si, and Al from blended fuels. At lower wheat straw shares, the release of K decreased due to reactions of KCl with Fe species, and Ti species, forming K2Fe2O4 and K2TiO3. At high wheat straw shares, the release of K could be mainly captured in the form of K2SO4; small amounts of KAlSiO4 were also observed in the bottom ash. When the wheat straw share was 80 wt.%, increasing temperatures enhanced the release of KCl(g) and NaCl(g) at 600–800 °C. By contrast, in the range of 800–1000 °C, the amounts of these gases released exhibited no apparent association with temperature. Compared with the release of K, fuel K was mainly retained in the bottom ash. The K2SO4 content in the bottom ash decreased with increasing temperature in the range of 600–1000 °C, whereas the fraction of K in the form of KAlSiO4 and KAlSiO6 increased with increasing temperature

  15. Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

    Indian Academy of Sciences (India)

    K V Amrute; U R Mhatre; S K Sinha; D C Kothari; R Nagarajan; D Kanjilal

    2002-05-01

    Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5 × 1013 and 7.5 × 1013 ions/cm2. The relative intensity ratios 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.

  16. “High-Throughput” Evaluation of Polymer-Supported Triazolic Appendages for Metallic Cations Extraction

    Directory of Open Access Journals (Sweden)

    Riadh Slimi

    2015-03-01

    Full Text Available The aim of this work was to find and use a low-cost high-throughput method for a quick primary evaluation of several metal extraction by substituted piperazines appendages as chelatants grafted onto Merrifield polymer using click-chemistry by the copper (I-catalyzed Huisgen’s reaction (CuAAC The polymers were tested for their efficiency to remove various metal ions from neutral aqueous solutions (13 cations studied: Li+, Na+, K+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Ba2+, Ce3+, Hg+ and Pb2+ using the simple conductimetric measurement method. The polymers were found to extract all metals with low efficiencies ≤40%, except for Fe3+ and Hg+, and sometimes Pb2+. Some polymers exhibited a selectively for K+, Cd2+ and Ba2+, with good efficiencies. The values obtained here using less polymer, and a faster method, are in fair correspondence (average difference ±16% with another published evaluation by atomic absorption spectroscopy (AAS.

  17. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  18. Alkali Aggregate Reaction in Alkali Slag Cement Mortars

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of "Mortar Bar Method",the ratio of cement to aggregate was kept as a constant 1∶2.25,the water-cement ratio of the mixture was 0.40,and six prism specimens were prepared for each batch of mixing proportions with dimensions of 10×10×60mm3 at 38±2℃ and RH≥95%, the influences of content and particle size of active aggregate, sort and content of alkali component and type of slag on the expansion ratios of alkali-activated slag cement(ASC) mortars due to alkali aggregate reaction(AAR) were studied. According to atomic absorption spectrometry,the amount of free alkali was measured in ASC mortars at 90d.The results show above factors affect AAR remarkably,but no dangerous AAR will occur in ASC system when the amount of active aggregate is below 15% and the mass fraction of alkali is not more than 5% (Na2O).Alkali participated in reaction as an independent component, and some hydrates containing alkali cations were produced, free alkalis in ASC system can be reduced enormously.Moreover,slag is an effective inhibitor, the possibility of generating dangerous AAR in ASC system is much lower at same conditions than that in ordinary Portland cement system.

  19. Effects of the ionization potential of the outer cations on the position of the charge-transfer bands for uranyl trinitrate compounds

    International Nuclear Information System (INIS)

    The authors used the low-temperature spectra (T = 4.2 and 77 K) of uranyl trinitrate compounds to examine the effects of outer alkali-metal cations and ammonium on the position of the purely electronic transition band V00. The spectra for the compounds are shown; the data show that cation substitution in the sequence K, Rb, NH4, Cs produces a monotone decrease in the pure electronic transition energy. The electronic transition frequency as a function of the ionization potential of the alkali melt are shown. The effect of the outer cation can be explained in terms of electron-density redistribution in the equitorial plane

  20. Optimized random phase approximation for the structure of liquid alkali metals as electron-ion plasmas

    International Nuclear Information System (INIS)

    The purpose of this letter is to stress that the way towards an unconventional optimized-random-phase-approximation (ORPA) approach to the structure of liquid metals is indicated, and in fact already a good first-order solution for such an approach is provided

  1. The effect of alkali metal on the surface properties of potassium doped Au-Beta zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Sobczak, Izabela, E-mail: sobiza@amu.edu.pl [A. Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan (Poland); Rydz, Michal; Ziolek, Maria [A. Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan (Poland)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Interaction of gold with K leads to the change of electronic state and redox properties of gold. ► The amount of potassium incorporated into Au-zeolites determines the size of gold particles. ► K(0.2 wt.%)/Au-Beta exhibits the best performance in decomposition of N{sub 2}O and removal of Bu{sub 2}S. -- Abstract: Beta zeolite was applied as support for gold introduced by gold-precipitation method and potassium added by impregnation or adsorption. The effect of zeolite composition and the amount of potassium introduced on the surface properties of the final materials was considered. Moreover, the interaction of gold and potassium species was found to be related to the adsorptive and catalytic behaviour of zeolites in NO reduction with propene and deodorization. K/Au-Beta(Impregnated) exhibits the best performance in the above mentioned processes because of the small gold particles (between 2 and 5 nm) and interaction of gold with potassium species leading to the change of electronic properties of the surface (the appearance of cationic gold species). Potassium added as a promoter improves the catalytic properties of Au-zeolite in N{sub 2}O decomposition and also in deodorization (increase of the ability to dibutyl sulphide oxidation). The catalysts prepared were characterized by XRD, XPS, UV–vis, TEM, pyridine adsorption combined with FTIR and test reaction (2-propanol transformation).

  2. FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Khachai, H; Haddou, A; Rached, D; Soudini, B [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-bel-Abbes, Sidi-bel-Abbes 22000 (Algeria); Khenata, R; Amrani, B [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, Mascara 29000 (Algeria); Bouhemadou, A [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, Setif 19000 (Algeria); Reshak, Ali H [Institute of Physical Biology, South Bohemia University, Nove Hrady 373 33 (Czech Republic)], E-mail: khenata_rabah@yahoo.fr, E-mail: a_bouhemadou@yahoo.fr

    2009-03-04

    The electronic and optical properties of M{sub 2}S (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure have been calculated, using a full relativistic version of the full-potential augmented plane-wave plus local orbitals method based on density functional theory, within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism (EV-GGA) is applied so as to optimize the corresponding potential for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with the available data. Band structure, density of states, electron charge density and pressure coefficients of energy gaps are given. Results obtained for band structure using EV-GGA are larger than those with LDA and GGA. It is found that the spin-orbit coupling lifts the triple degeneracy at the {gamma} point and the double degeneracy at the X point. The analysis of the electron charge density shows that the M-S bonds have a significant ionic character. The complex dielectric functions {epsilon}{sub 2}({omega}) for alkali metal sulfides were calculated for radiation up to 30 eV and the assignment of the critical points to the band structure energy differences at various points of the Brillouin zone was made. The pressure and volume dependence of the static dielectric constant and the refractive index are calculated.

  3. Evidence for alkali metal induced intermolecular acetylenic hydrogen atom transfer between hydrogen-bonded alkyne complexes in solid argon

    International Nuclear Information System (INIS)

    Condensation of acetylene, propyne, and 2-butyne/acetylene mixtures with heavy alkali metal atoms (Na, K, Cs) in an argon matrix at 15 K has led to the appearance of infrared absorptions due to ethylene, propylene, and trans-2-butene, respectively. These results stand in sharp contrast with the products obtained with lithium. Isotopic studies have shown that ethylene formation involved three different acetylene molecules and evidenced a difference in the product yield with hydrogen vs. deuterium as well as a preference for trans- vs. cis-C2H2D2 formation, which is discussed and rationalized by differences in the zero point energies for the different mixed deuterium isotopes of the intermediate vinyl radical. This trend is amplified by methyl substitution. Spectroscopic evidence was found in these experiments for cesium acetylide (Cs+C2H-) and a cesium-acetylene π complex, which are involved in the intermolecular acetylenic hydrogen atom transfer process. 26 references, 3 figures, 2 tables

  4. FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

    International Nuclear Information System (INIS)

    The electronic and optical properties of M2S (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure have been calculated, using a full relativistic version of the full-potential augmented plane-wave plus local orbitals method based on density functional theory, within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism (EV-GGA) is applied so as to optimize the corresponding potential for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with the available data. Band structure, density of states, electron charge density and pressure coefficients of energy gaps are given. Results obtained for band structure using EV-GGA are larger than those with LDA and GGA. It is found that the spin-orbit coupling lifts the triple degeneracy at the Γ point and the double degeneracy at the X point. The analysis of the electron charge density shows that the M-S bonds have a significant ionic character. The complex dielectric functions ε2(ω) for alkali metal sulfides were calculated for radiation up to 30 eV and the assignment of the critical points to the band structure energy differences at various points of the Brillouin zone was made. The pressure and volume dependence of the static dielectric constant and the refractive index are calculated.

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

    International Nuclear Information System (INIS)

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

  6. 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.

  7. Yarrowia lipolytica possesses two plasma membrane alkali metal cation/H+ antiporters with different functions in cell physiology

    Czech Academy of Sciences Publication Activity Database

    Papoušková, Klára; Sychrová, Hana

    2006-01-01

    Roč. 580, č. 8 (2006), s. 1971-1976. ISSN 0014-5793 R&D Projects: GA ČR(CZ) GD204/03/H066; GA ČR(CZ) GA206/05/0035; GA MŠk(CZ) LC531 Institutional research plan: CEZ:AV0Z50110509 Keywords : yeast * heterologous expression * Na+/H+ antiporter Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.372, year: 2006

  8. Synthesis and luminescence of high-brightness Gd2O2SO4:Tb3+ nanopieces and the enhanced luminescence by alkali metal ions co-doping

    International Nuclear Information System (INIS)

    Gd2O2SO4:Tb3+ nanopieces were synthesized by a combined approach of electrospinning and calcination at 1000 °C in mixed gas of sulfur dioxide and air. The nanopieces excited by a 230 nm light showed excellent green luminescence with the strongest emission peak at 545 nm due to the 5D4→7F5 transition of Tb3+. Interestingly, the intensity of emission peak at 545 nm of Gd2O2SO4:Tb3+ nanopieces exhibited about two times stronger than that of the bulk Gd2O2SO4:Tb3+ at the same doping concentrations of Tb3+. Besides, the effects of alkali metal ions doping on the luminescence of the nanopieces have been examined. The emission intensities were further enhanced by alkali metal ions doping, especially for Gd2O2SO4:Tb3+/Li+. The optimal doping concentration of Li+ was 7%. -- Highlights: •Gd2O2SO4:Tb3+ nanopieces were prepared via electrospinning followed by calcination. •A comparison between the nanopieces and the bulk was conducted. •The effects of alkali metal ions on the luminescence of nanopieces are examined. •The content of co-dopant in nanopieces is optimized. •The potential applications of the nanopieces and the facile method are suggested

  9. Magnetometry with millimeter-scale anti-relaxation-coated alkali-metal vapor cells

    CERN Document Server

    Balabas, M V; Kitching, J; Schwindt, P D D; Stalnaker, J E

    2005-01-01

    Dynamic nonlinear magneto-optical-rotation signals with frequency- and amplitude-modulated laser light have been observed and investigated with a spherical glass cell of 3-mm diameter containing Cs metal with inner walls coated with paraffin. Intrinsic Zeeman relaxation rates of $\\gamma/(2\\pi)\\approx 20 $Hz and lower have been observed. Favorable prospects of using millimeter-scale coated cells in portable magnetometers and secondary frequency references are discussed.

  10. X-ray and neutron diffraction studies of some liquid alkali metals and alloys

    International Nuclear Information System (INIS)

    Experimental techniques and correction procedures have been searched for, which allow a reliable and accurate determination of the structure factors of simple liquid metals, particularly in the small-angle region. A study of binary alloys was carried out and showed that clustering of like atoms (a tendency to phase separation) occurs, indicating special structural aspects. The densities of Na-K, Na-Cs, K-Rb alloys were also measured. (C.F.)

  11. Fast detection of oxygen by the naked eye using a stable metal-organic framework containing methyl viologen cations.

    Science.gov (United States)

    Gong, Yun-Nan; Lu, Tong-Bu

    2013-09-11

    A stable porous metal-organic framework (MOF) containing methyl viologen cations exhibits reversible photochromic, thermochromic and fluorescence changes via host-guest interactions, and can be used for fast and selective detection of oxygen by naked eye recognition of color change within five seconds. PMID:23877538

  12. Identification of a crucial histidine involved in metal transport activity in the Arabidopsis cation/H(+) exchanger CAX1

    Science.gov (United States)

    In plants, yeast and bacteria, cation/H(+) exchangers (CAXs), have been shown to translocate Ca(2+) and other metals. The best characterized of these related transporters is the plant vacuolar-localized CAX1. We used site-directed mutagenesis to assess the impact of altering the seven histidine re...

  13. Effect of heavy metal cations on the fate of extracellular DNA adsorbed and bound on clay minerals.

    OpenAIRE

    Ascher J.; Ceccherini M.T.; Arfaioli P.; Borgogni F.; Pietramellara G.

    2011-01-01

    The presence of high-valent metal cations on clay mineral surfaces is hypothesised to induce conformational changes in the secondary and tertiary structure of the DNA molecule adsorbed and bound onto clays, defined as M-conformation, and its condensation. The hypothesis that these reversible phenomena could enhance the resistance of DNA to enzymatic degradation strongly encourages the studies on the effects of heavy metal contamination in clay rich soils on the fate of extracellular soil DNA ...

  14. Construction of thermionic alkali-ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Ul Haq, F.

    1986-04-01

    A simple technique is described by which singly charged alkali ions of K, Na, Li, Rb and Cs are produced by heating ultra-pure chemical salts of different alkali metals on tungsten filaments without employing a temperature measuring device. The character of alkali-ion currents at different heating powers and the remarkably constant ion emission current for prolonged periods are discussed.

  15. From T2,2@Bmmim to Alkali@T2,2@Bmmim Ivory Ball-like Clusters: Ionothermal Syntheses, Precise Doping, and Photocatalytic Properties.

    Science.gov (United States)

    Du, Cheng-Feng; Li, Jian-Rong; Zhang, Bo; Shen, Nan-Nan; Huang, Xiao-Ying

    2015-06-15

    Presented here are the syntheses, structures, and properties of an In-Sn-Se compound based on a ternary super-supertetrahedral T2,2 cluster nested by Bmmim cations and two of its alkali-doped quaternary analogues. By means of a one-pot ionothermal method, an alkali metal ion (Cs(+) or Rb(+)) could be precisely doped into the central cavity of the cluster, forming an alkali@T2,2@Bmmim quaternary cluster. Remarkably, the undoped compound exhibited excellent stability and visible light photodegradation ability over a wide range of pH, especially in acidic conditions. PMID:26034842

  16. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

    Science.gov (United States)

    Joshi, Ashok V.; Balagopal, Shekar; Pendelton, Justin

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

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

    CERN Document Server

    Gopakumar, Geetha; Hada, Masahiko; Kajita, Masatoshi

    2014-01-01

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

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

    CERN Document Server

    Tomza, Michał

    2014-01-01

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

  19. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    DEFF Research Database (Denmark)

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe......, V and oxygen where at least some of the V is in the tetravalent state. USE-(I) is a cathode active material in electric current producing storage cells. ADVANTAGE-Use of (I) in Li or alkali metal batteries gives prolonged life cycles.Storage cells using (I) have improved capacity during charge and...

  20. Electronic structure of alkali metal hydrides on data of cluster calculations by LCAO MO SCF CNDO

    International Nuclear Information System (INIS)

    The results of quantum-chemical study in where by M = Li, Na, K, Rb and Cs, are presented. The calculation expresses the expected electron density distributions in hydrides on the hydrogen and metal atoms as well as the energy characteristics: M-H, M-M and compounds binding energies. The latter ones qualitatively correlate with the binding energies of LiH-CsH compounds. The calculated values for the Fermi energy and the width of the forbidden zone at the Fermi level make it possible to suppose that the ideally formed lithium hydride crystal will be characterized by the highest electrical resistance. It is established that quantum-chemical characteristics of the MH hydrides structure change nonmonotonously by transfer from Li to Cs

  1. Yeast 14-3-3 proteins participate in the regulation of cell cation homeostasis via interaction with Nha1 alkali-metal-cation/proton antiporter

    Czech Academy of Sciences Publication Activity Database

    Zahrádka, Jaromír; Van Heusden, G.P.H.; Sychrová, Hana

    2012-01-01

    Roč. 1820, č. 7 (2012), s. 849-858. ISSN 0304-4165 R&D Projects: GA MŠk(CZ) LC531; GA MŠk(CZ) OC10012; GA AV ČR(CZ) IAA500110801 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : yeast * 14-3-3 proteins * ion homeostasis * Nha1 antiporter Subject RIV: CE - Biochemistry Impact factor: 3.848, year: 2012

  2. Complex formation during dissolution of metal oxides in molten alkali carbonates

    DEFF Research Database (Denmark)

    Li, Qingfeng; Borup, Flemming; Petrushina, Irina;

    1999-01-01

    as the partial pressure of carbon dioxide varies. By combination of solubility and electromotive force measurements, a model is constructed assuming the dissolution involves complex formation. The possible species for lead are proposed to be [Pb(CO3)(2)](-2) and/or [Pb(CO3)(3)](-4). A similar complex......Dissolution of metal oxides in molten carbonates relates directly to the stability of materials for electrodes and construction of molten carbonate fuel cells. In the present work the solubilities of PbO, NiO, Fe2O3,and Bi2O3 in molten Li/K carbonates have been measured at 650 degrees C under...... carbon dioxide atmosphere. It is found that the solubilities of NiO and PbO decrease while those of Fe2O3 and Bi2O3 remain approximately constant as the lithium mole fraction increases from 0.43 to 0.62 in the melt. At a fixed composition of the melt, NiO and PbO display both acidic and basic dissolution...

  3. Estimation of alkali metal mole percent and weight of calcined solids for ICPP calcine

    International Nuclear Information System (INIS)

    An updated method is given for estimation of the weight of calcined solids and volume reduction factor for calcine, and mole percent sodium plus potassium in calcine produced from radioactive waste in a fluidized-bed calciner at the Idaho Chemical Processing Plant (ICPP). It incorporates new information on a calcine chemistry from a study by K. N. Brewer and G. F. Kessinger in which they determined the compounds formed during calcination by both high temperature thermodynamic equilibrium calculations and by analyses of pilot-plant calcines. An explanation of the assumptions made in the calculations, along with several example calculations and comparisons with the previous calculation methods are included. This method allows calculation of the heat generation rate and sodium content of the calcine, which are used to determine the suitability of the calcine for storage in the ICPP bin sets. Although this method accurately predicts the weight of calcine and mole percent Na + K for its intended purpose, the compounds predicted should only be used as a first approximation for other purposes since the calculation does not incorporate all of the compounds, such as mixed-metal oxides, which may form during calcination

  4. An experimental study of charge exchange process in the energy range 1-30 keV during the passage of alkali metal ions and atoms through cesium and potassium vapour

    International Nuclear Information System (INIS)

    An experimental study is presented of the charge exchange processes in the energy range of about 1-30 keV during the passage of positive alkali ions and alkali atoms through potassium and cesium vapour. The experimental set-up designed for this experiment includes a thermionic source for positive alkali ions with an acceleration stage, a first charge exchange cell to produce fast alkali atoms, a second charge exchange cell with a surface ionisation detector to determine the alkali metal vapor target thickness and a detection system with electrostatic bending of the charged secondary species. The maximum negative ion yield has been determined for the collision systems Li+ + K, Na+ + K, K+ + K, and Rb+ + K, and for another eleven systems the charge transfer cross-sections have been measured too. (orig./GG)

  5. Soil sampling and analysis plan for the 3718-F Alkali Metal Treatment and Storage Facility closure activities

    International Nuclear Information System (INIS)

    Amendment V.13.B.b to the approved closure plan (DOE-RL 1995a) requires that a soil sampling and analysis plan be prepared and submitted to the Washington State Department of Ecology (Ecology) for review and approval. Amendment V.13.B.c requires that a diagram of the 3718-F Alkali Metal Treatment and Storage Facility unit (the treatment, storage, and disposal [TSD] unit) boundary that is to be closed, including the maximum extent of operation, be prepared and submitted as part is of the soil sampling and analysis plan. This document describes the sampling and analysis that is to be performed in response to these requirements and amends the closure plan. Specifically, this document supersedes Section 6.2, lines 43--46, and Section 7.3.6 of the closure plan. Results from the analysis will be compared to cleanup levels identified in the closure plan. These cleanup levels will be established using residential exposure assumptions in accordance with the Model Toxics Control Act (MTCA) Cleanup Regulation (Washington Administrative Code [WAC] 173-340) as required in Amendment V.13.B.I. Results of all sampling, including the raw analytical data, a summary of analytical results, a data validation package, and a narrative summary with conclusions will be provided to Ecology as specified in Amendment V.13.B.e. The results and process used to collect and analyze the soil samples will be certified by a licensed professional engineer. These results and a certificate of closure for the balance of the TSD unit, as outlined in Chapter 7.0 of the approved closure plan (storage shed, concrete pad, burn building, scrubber, and reaction tanks), will provide the basis for a closure determination

  6. Alkali metal Rankine cycle boiler technology challenges and some potential solutions for space nuclear power and propulsion applications

    Energy Technology Data Exchange (ETDEWEB)

    Stone, J.R.

    1994-07-01

    Alkali metal boilers are of interest for application to future space Rankine cycle power conversion systems. Significant progress on such boilers was accomplished in the 1960's and early 1970's, but development was not continued to operational systems since NASA's plans for future space missions were drastically curtailed in the early 1970's. In particular, piloted Mars missions were indefinitely deferred. With the announcement of the Space Exploration Initiative (SEI) in July 1989 by President Bush, interest was rekindled in challenging space missions and, consequently in space nuclear power and propulsion. Nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) were proposed for interplanetary space vehicles, particularly for Mars missions. The potassium Rankine power conversion cycle became of interest to provide electric power for NEP vehicles and for 'dual-mode' NTP vehicles, where the same reactor could be used directly for propulsion and (with an additional coolant loop) for power. Although the boiler is not a major contributor to system mass, it is of critical importance because of its interaction with the rest of the power conversion system; it can cause problems for other components such as excess liquid droplets entering the turbine, thereby reducing its life, or more critically, it can drive instabilities-some severe enough to cause system failure. Funding for the SEI and its associated technology program from 1990 to 1993 was not sufficient to support significant new work on Rankine cycle boilers for space applications. In Fiscal Year 1994, funding for these challenging missions and technologies has again been curtailed, and planning for the future is very uncertain. The purpose of this paper is to review the technologies developed in the 1960's and 1970's in the light of the recent SEI applications. In this way, future Rankine cycle boiler programs may be conducted most efficiently.

  7. Alkali and alkaline metal oxide materials for high temperature CO2 sorption studies

    International Nuclear Information System (INIS)

    In recent years, a number of novel ceramic oxide materials have emerged that are capable of absorbing CO2 at high temperatures (>500OC) while remaining stable over a large number of cycles and a wide range of temperatures. The most promising are been considered for carbon capture applications – specifically, for use in combustion chambers and the smoke stacks of power plants where combustion gases which contain primarily a mixture of CO2 and N2 at high temperature. Compared to other CO2 sequestration technologies, these ceramics have some advantages (eg. chemisorption at high temperatures) and disadvantages (eg. limited kinetics over time). Examples of oxides already known to show significant CO2 absorption include Li5AlO4, Li6Zr2O7, Na2ZrO3 and Ba4Sb2O9. The phase formations and structural evolution of these metal oxides have been studied under environmental conditions mimicking those found in combustion chambers and power plants, over the temperature range 873–1173 K. CO2 absorption by these materials is believed to proceed through a layering effect of the sorbent material, explained through a core-shell model. Each phase is represented as a layer covering a particle, with the outermost layer exposed and allowed to react with the environment. Detailed studies into the mechanism of CO2 absorption and the material layers will shed more information that can be used to fine tune the materials to increase their CO2 absorption capacity. Previous work has focused on the identification of phases ex situ and studies of their practical absorption capacity and kinetics. The new work we will present here uses a combination of a xray spectroscopy, x-ray and neutron diffraction, to understand both how the sorption process works and how the structural evolution of the phases affects the CO2 sorption of the materials over time in-situ.

  8. Cation-Exchange Equilibria with Fused Salts

    International Nuclear Information System (INIS)

    Solute distributions of alkali metal, alkaline- earth, transition metal, and actinide ions have been studied in fused salt-cation exchanger systems. The fused salts employed were alkali halides and nitrates. The cation exchangers used were natural zeolites, synthetic zeolites, high-porosity glasses, and molten oxide mixtures. The molten exchangers were composed of Na2O and B2O3 in various proportions. The relative quantities not only determined the exchanger capacity and electrolyte penetration but also produced distribution coefficients for a given solute which varied over several orders of magnitude. Moreover, they produced marked reversals in the selectivity series. Additional studies on the anion distributions, miscibility diagrams, vapour pressures and diffusion rates in these systems have elucidated the mechanisms involved and the relation of selectivity to solute properties, system thermodynamics, exchanger structure and available functional groups. In the region of high Na2O composition, the distribution coefficients for mono-, di- and trivalent cations in NaCl have not only the same order of selectivity found in Dowex 50-HCl systems but also similar values for the distribution coefficients. The results are summarized qualitatively and compared to behaviour in aqueous systems (Table VII). (author)

  9. Antibacterial Dyeing of Wool with Natural Cationic Dye Using Metal Mordants

    Directory of Open Access Journals (Sweden)

    Aminoddin HAJI

    2012-09-01

    Full Text Available In this study, Berberine colorant extracted from berberis vulgaris root was applied on wool fiber using alum (aluminum potassium sulfate, copper sulfate and potassium dichromate as mordant. The effect of treatment variables such as amount of mordant, time and temperature on the color strength of dyed fibers was examined. The fastness properties of dyed wool against washing, light and wet rubbing were evaluated. the use of metal mordants increased the color strength of the dyed goods. Increase in dyeing time and temperature caused deeper shades. All mordants, increased the rub fastness and wash fastness of dyed samples, but the light fastness was increased except in case of alum. Berberine is a cationic dye and because of it's quaternary ammonium structure can act as an antibacterial agent. So, dyed samples were tested for antibacterial activity using AATCC test method 100-2004. The dyed wool represented a high level of antibacterial activity. The extract of the berberis vulgaris can be considered as a natural dye of acceptable fastness properties together with excellent antibacterial activity for woolen textiles.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2437

  10. Two anionic metal-organic frameworks with tunable luminescent properties induced by cations

    Science.gov (United States)

    Chen, Shu-Mei; Chen, Yan-Fei; Liu, Liyang; Wen, Tian; Zhang, Hua-Bin; Zhang, Jian

    2016-03-01

    Two three-dimensional (3-D) MOFs, [(C2H5)4N)]3[H3O]2[Cd6Br(H2-DHBDC)8(DMF)4] (1; H4-DHBDC=2,5-dihydroxy-1,4-benzenedicarboxylic acid, DMF=N,N-dimethylformamide) and [(CH3)2NH2]2[Cd3(H2-DHBDC)4(DMF)2]·2DMF(2), are prepared from the self-assembly reactions between Cd(CH3COO)2 and H4-DHBDC, respectively. Both anionic frameworks consist of linear trinuclear Cd units (e.g., 1: [Cd3BrO2(CO2)7] and [Cd3O2(CO2)8]; 2: [Cd3O2(CO2)8]) linked by the H2-DHBDC ligands. The photoluminescent properties of compound 1 are tunable through cation-exchange with different metal ions. The results demonstrated an effective ion-exchange approach toward the functional modification of MOF materials.

  11. Surface and antitumor activity of some novel metal-based cationic surfactants

    Directory of Open Access Journals (Sweden)

    Badawi A

    2007-01-01

    Full Text Available The development of anticancer metal-based drugs was attempted by reacting dodecyl amine with selenious acid to produce a quaternary ammonium salt which was then converted to copper and cobalt cationic complexes via complexing the first compounds with copper (II or cobalt (II ions. The surface properties of these surfactants were investigated. The surface properties studied included critical micelle concentration (CMC, maximum surface excess (Γmax , and minimum surface area (Amin . Free energy of micellization (∆G o mic and adsorption (∆Go ads were calculated. Antitumor activity was tested by using Ehrlich ascites carcinoma (EAC as a model system of mice cell tumor. The compounds were also tested in vitro on five human monolayer tumor cell lines: MCF 7 (breast carcinoma, HEPG 2 (liver carcinoma, U 251 (brain tumor, HCT116 (colon carcinoma, and H460 (lung carcinoma. FTIR spectra, elemental analysis, and H 1 NMR spectra were performed to insure the purity of the prepared compounds.

  12. Probing alkali metal–π interactions with the side chain residue of tryptophan

    OpenAIRE

    Hu, Jiaxin; Barbour, Leonard J.; Gokel, George W.

    2002-01-01

    Feeble forces play a significant role in the organization of proteins. These include hydrogen bonding, hydrophobic interactions, salt bridge formation, and steric interactions. The alkali metal cation-π interaction is a force of potentially profound importance but its consideration in biology has been limited by the lack of experimental evidence. Our previous studies of cation–π interactions with Na+ and K+ involved the side arms of tryptophan (indole), tyrosine (phenol),...

  13. CO2 Extraction from Ambient Air Using Alkali-Metal Hydroxide Solutions Derived from Concrete Waste and Steel Slag

    Science.gov (United States)

    Stolaroff, J. K.; Lowry, G. V.; Keith, D. W.

    2003-12-01

    To mitigate global climate change, deep reductions in CO2 emissions are required in the coming decades. Carbon sequestration will play a crucial role in this reduction. Early adoption of carbon sequestration in low-cost niche markets will help develop the technology and experience required for large-scale deployment. One such niche may be the use of alkali metals from industrial waste streams to form carbonate minerals, a safe and stable means of sequestering carbon. In this research, the potential of using two industrial waste streams---concrete and steel slag---for sequestering carbon is assessed. The scheme is outlined as follows: Ca and Mg are leached with water from a finely ground bed of steel slag or concrete. The resulting solution is sprayed through air, capturing CO2 and forming solid carbonates, and collected. The feasibility of this scheme is explored with a combination of experiments, theoretical calculations, cost accounting, and literature review. The dissolution kinetics of steel slag and concrete as a function of particle size and pH is examined. In stirred batch reactors, the majority of Ca which dissolved did so within the first hour, yielding between 50 and 250 (mg; Ca)/(g; slag) and between 10 and 30 (mg; Ca)/(g; concrete). The kinetics of dissolution are thus taken to be sufficiently fast to support the type of scheme described above. As proof-of-concept, further experiments were performed where water was dripped slowly through a stagnant column of slag or concrete and collected at the bottom. Leachate Ca concentrations in the range of 15 mM were achieved --- sufficient to support the scheme. Using basic physical principles and numerical methods, the quantity of CO2 captured by falling droplets is estimated. Proportion of water loss and required pumping energy is similarly estimated. The results indicate that sprays are capable of capturing CO2 from the air and that the water and energy requirements are tractable. An example system for

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

    Indian Academy of Sciences (India)

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

    2014-09-01

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

  15. 盐碱胁迫下燕麦生长及阳离子吸收特征%Oat growth and cation absorption characteristics under salt and alkali stress

    Institute of Scientific and Technical Information of China (English)

    范远; 任长忠; 李品芳; 任图生

    2011-01-01

    This paper monitored the oat growth and cation absorption characteristics on a saline-alkali soil in the Baicheng region of Jilin Province under low, medium, and high levels of salt stress. No significant differences were observed in the shoot growth and yield components under the three levels of salt stress, but the root biomass and root/shoot ratio decreased significantly with increasing salt stress level. At maturing stage, the root/shoot ratio under medium and high salt stressecs was 77.2% and 64.5% of that under low salt stress, respectively. Under the three levels of salt stress, the K+/Na+ and Ca2+/Na+ ratios in oat plant had significant differences at trefoil stage, but no significant differences at heading stage. With the increase of salt stress level, the cation absorption selectivity coefficient of oat at filling stage decreased significantly, but the transportation selectivity coefficient had no significant difference under the three levels of stress. It was concluded that oat could adapt to the salt and alkali stress of soda-alkaline soil to some extent, and the adaptation capability decreased with the increasing level of stress. The decrease of oat root biomass and the stronger ion selective absorption capacity at heading stage under salt and alkali stress could benefit the shoot growth and yield components of oat.%在吉林白城地区盐碱土上监测了3个盐分胁迫水平下燕麦的生长动态及对土壤阳离子的吸收特征.结果表明:在低度、中度和高度3个胁迫水平下燕麦地上部生长和产量构成因素没有显著差异,但根部干质量和根冠比随盐碱胁迫程度的加重而显著降低,在成熟期,中度和高度胁迫下的根冠比分别是低度胁迫下的77.2%和64.5%.3个胁迫水平下燕麦的K+/Na+和Ca2+/Na+在三叶期差异最大,而在抽穗期无显著差异.随着盐分胁迫程度的加重,燕麦的离子吸收选择性系数在灌浆期显著降低,而运输选择性系数无显著变

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

    OpenAIRE

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

    1999-01-01

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

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

    Science.gov (United States)

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

    1999-12-01

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

  18. Synthesis of calix(aza)crown and its oligomeric analogue for the extraction of selected metal cations and dichromate anions

    Energy Technology Data Exchange (ETDEWEB)

    Akkus, Guelderen Uysal [Department of Chemistry, Afyon Kocatepe University, Afyonkarahisar (Turkey); Memon, Shahabuddin [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro (Pakistan); Sezgin, Mehmet; Yilmaz, Mustafa [Department of Chemistry, Selcuk University, Konya (Turkey)

    2009-02-15

    The present study reports the synthesis of a novel ionophore, calix[4]azacrown (5) bearing two amino groups at the lower rim along with its oligomeric analogue (6). The liquid-liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that (5) and (6) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species (5) shows remarkable extraction properties at low pH, whereas species (6) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Solid-State Properties of One-Dimensional Metals Based on bis(oxalato)platinate Anions with Divalent Cations

    DEFF Research Database (Denmark)

    Braude, A.; Carneiro, K.; Jacobsen, Claus Schelde;

    1987-01-01

    The crystal structures, superstructures, dc conductivity, optical properties, and thermopower of six linear-chain conductors of the type M0.8[Pt(C2O4)2]⋅(M=Ni,Co,Zn,Fe,Mg,Mn), where M is a divalent metal (M=Ni,Co,Zn,Fe,Mg,Mn), have been studied. At high temperatures they form a common orthorhombic...... metallic phase (I) with conductivities of 30–200 (Ω cm)-1 and thermopowers of 5–10 μV/K, with the lattice weakly modulated by the one-dimensional Peierls distortion. Below T1, three compounds (Ni,Co,Zn) form a semiconducting phase (A-II) due to the ordering of the [M(H2O)6]+2 cations. As the cation...

  20. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  1. Use of membranes for heavy metal cationic wastewater treatment: flotation and membrane filtration

    Energy Technology Data Exchange (ETDEWEB)

    Sudilovskiy, P.S.; Kagramanov, G.G.; Trushin, A.M.; Kolesnikov, V.A. [D.I. Mendeleyev University of Chemical Technology of Russia, Moscow (Russian Federation)

    2007-08-15

    A new water treatment process - membrane flotation - is presented. The hydrodynamics of air sparging with the use of microporous membranes was studied as well as the membrane flotation efficacy for cationic wastewater treatment. The performance of membrane filtration processes was evaluated. Ways of integration of flotation and membrane filtration in cationic wastewater treatment practice are discussed. (orig.)

  2. Composition of outer-sphere cations as a tool for electrochemical synthesis of novel niobium compounds

    Directory of Open Access Journals (Sweden)

    Grinevitch V.V.

    2003-01-01

    Full Text Available The individual alkali-metal cation influence on the chemical and phase composition of electrosynthesis products has been studied in fluoride solvents with different O/Nb ratios. It was shown that the cation nature of molten electrolytes is a powerful tool to control the chemical and phase composition of the cathodic products of electrolysis in oxy-fluoride and fluoride melts. New niobium compounds were obtained by electrochemical synthesis using the outer-sphere cations composition control: tetragonal Nb6O, rhombohedral sub-oxide NbxO (x<6 and composite compounds "NbO" ⋅n"MeF" (Me=K, Rb, n=1, 2.

  3. Activation analysis for measurements of silicon, phosphorus, alkali metals and other elements in high-purity metals

    International Nuclear Information System (INIS)

    In the present thesis, methods of activation analysis were developed for the determination of the elements silicon, phosphorus, potassium, sodium, i.a. in the high-purity metals vanadium, niobium, tantalum, tungsten, molybdenum and iron. The determination of silicon is based on the activation of samples with reactor neutrons, on a subsequent radiochemical separation of the tracer radionuclide 31Si resulting from the reaction 30Si(n,γ), and on the measurement of β activity with the help of a liquid scintillation measuring desk. Since the tracer radionuclide 31Si almost exclusively emits β rays which are not sufficiently nuclide-specific, silicon was selectively separated from the other sample elements by being distilled as silicon tetrafluoride. The processing of the residue following the separation of silicon permits a complementary gamma-spectroscopic determination of a whole lot of additional elements. Thus, the separation of the nuclide 182Ta with the anion exchanger Dowex 1X8 from HF/H2SO4 medium permits the determination of 22 elements in vanadium, niobium and tantalum. Phosphorus content is determined by activating the samples with rapid neutrons (cyclotrons) via the reaction 31P(n,p)31Si. (orig./MM)

  4. Network diversity through decoration of trigonal-prismatic nodes: Two-step crystal engineering of cationic metal-organic materials

    KAUST Repository

    Schoedel, Alexander

    2011-10-05

    MOMs the word! In a two-step process, first a trigonal-prismatic Primary Molecular Building Block ([Cr3O(isonic)6]+, tp-PMBB-1) was formed and then it was connected to linear linkers or square-planar nodes to afford three novel highly charged cationic metal-organic materials (MOMs) with snx, snw, and stp topologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. NMR Structure and CD Titration with Metal Cations of Human Prion α2-Helix-Related Peptides

    Directory of Open Access Journals (Sweden)

    Luisa Ronga

    2007-01-01

    Full Text Available The 173–195 segment corresponding to the helix 2 of the C-globular prion protein domain could be one of several “spots” of intrinsic conformational flexibility. In fact, it possesses chameleon conformational behaviour and gathers several disease-associated point mutations. We have performed spectroscopic studies on the wild-type fragment 173–195 and on its D178N mutant dissolved in trifluoroethanol to mimic the in vivo system, both in the presence and in the absence of metal cations. NMR data showed that the structure of the D178N mutant is characterized by two short helices separated by a kink, whereas the wild-type peptide is fully helical. Both peptides retained these structural organizations, as monitored by CD, in the presence of metal cations. NMR spectra were however not in favour of the formation of definite ion-peptide complexes. This agrees with previous evidence that other regions of the prion protein are likely the natural target of metal cation binding.

  6. Synthesis and Structural Characterization of Complexes of a DO3A-Conjugated Triphenylphosphonium Cation with Diagnostically Important Metal Ions

    OpenAIRE

    Yang, Chang-Tong; Li, Yongxin; Liu, Shuang

    2007-01-01

    To understand the coordination chemistry of a DO3A-conjugated triphenylphosphonium (TPP) cation, triphenyl(4-((4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)methyl)benzyl)phosphonium (DO3A-xy-TPP), with diagnostically important metal ions, In(DO3A-xy-TPP)+, Ga(DO3A-xy-TPP)+ and Mn(DO3A-xy-TPP) were prepared by reacting DO3A-xy-TPP with one equivalent of the respective metal salt. All three complexes have been characterized by elemental analysis, IR, ESI-MS, NMR methods for In(...

  7. Calculation of van der Walls coefficients of alkali metal clusters by hydrodynamic approach to time-dependent density-functional theory

    CERN Document Server

    Banerjee, A; Banerjee, Arup; Harbola, Manoj K.

    2004-01-01

    In this paper we employ the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waal coefficients $C_{6}$ and $C_{8}$ of alkali-metal clusters of various sizes including very large clusters. Such calculation becomes computationally very demanding in the orbital-based Kohn-Sham formalism, but quite simple in the hydrodynamic approach. We show that for interactions between the clusters of same sizes, $C_{6}$ and $C_{8}$ sale as the sixth and the eighth power of the cluster radius rsepectively, and approach the respective classically predicted values for the large size clusters.

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

    OpenAIRE

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

    1992-01-01

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

  9. Ab initio study of the adsorption, diffusion, and intercalation of alkali metal atoms on the (0001) surface of the topological insulator Bi2Se3

    International Nuclear Information System (INIS)

    Ab initio study of the adsorption, diffusion, and intercalation of alkali metal adatoms on the (0001) step surface of the topological insulator Bi2Se3 has been performed for the case of low coverage. The calculations of the activation energies of diffusion of adatoms on the surface and in van der Waals gaps near steps, as well as the estimate of diffusion lengths, have shown that efficient intercalation through steps is possible only for Li and Na. Data obtained for K, Rb, and Cs atoms indicate that their thermal desorption at high temperatures can occur before intercalation. The results have been discussed in the context of existing experimental data

  10. Metal-Cation Recognition in Water by a Tetrapyrazinoporphyrazine-Based Tweezer Receptor

    Czech Academy of Sciences Publication Activity Database

    Lochman, L.; Švec, J.; Roh, J.; Kirakci, Kaplan; Lang, Kamil; Zimčík, P.; Nováková, V.

    2016-01-01

    Roč. 22, č. 7 (2016), s. 2417-2426. ISSN 0947-6539 Institutional support: RVO:61388980 Keywords : cations * crown compounds * fluorescent probes * phthalocyanines * sensor s Subject RIV: CA - Inorganic Chemistry Impact factor: 5.731, year: 2014

  11. Cation sorption at the smectite edges: From transition metals to Y and Lu

    International Nuclear Information System (INIS)

    Complete text of publication follows: Introduction: Clay minerals can adsorb trace elements in soils and weathering formations, a sorption property which is also a key-point for the use of clay materials in nuclear waste repositories. Retention can occur either by adsorption on the clay basal plane or at the layer edges, depending on physicochemical conditions. Building on previous identification of sorption sites of transition metals [1-3], this study shows how the geometry of Y and Lu surface complexes on layer edges of clay minerals can be identified. Materials and methods: Suspensions of purified clay minerals (hectorite or Al-montmorillonite, 2 and 1 g/L, respectively) were reacted in 0.5 M NaCl at pH 6 (Al-montmorillonite) and 7 (hectorite) with sorbates at concentrations of 50 μM (Y) and 100 μM (Lu). Self-supporting films of reacted clay minerals were obtained by slowly filtering suspension aliquots on cellulose nitrate filters. Yttrium K-edge and Lu L3-edge polarized EXAFS (PEXAFS) spectra of the self-supporting films were collected in fluorescence mode on the FAME beamline (ESRF, France). PEXAFS data were reduced, and analyzed using standard procedures. Results and interpretation: Small but significant angular dependences were observed for all P-EXAFS data, meaning that the Y and Lu binding environments are anisotropic. Coordination spheres of 7 O at 2.36 Angstroms and 8 O at 2.27 Angstroms, were observed for Y and Lu, respectively, comparable with d(Ln-O) distances measured by EXAFS spectroscopy [4]. Lutetium sorbed on Al-montmorillonite was surrounded by an Al-shell at 3.35 Angstroms, consistent with Lu sharing edges with Al octahedra and partially incorporated in a gibbsite-like interlayer. Both Y and Lu sorbed on hectorite were surrounded by cationic shells. Modelling of these cationic contributions yielded one out-of-plane Si/Mg shell at 3.16 Angstroms (Y) or 3.04 Angstroms (Lu), and two in-plane (Mg/Si) shells at 3.50, and 3.97 Angstroms for Y, or

  12. Density functional theory study of interaction, bonding and affinity of group IIb transition metal cations with nucleic acid bases

    Science.gov (United States)

    Bagchi, Sabyasachi; Mandal, Debasish; Ghosh, Deepanwita; Das, Abhijit K.

    2012-05-01

    The structure, bonding, and energetics of the complexes obtained from the interaction between the most stable tautomeric forms of free DNA and RNA bases and Zn2+, Cd2+ and Hg2+ cations have been studied using density functional B3LYP method. The 6-311+G (2df, 2p) basis set along with LANL2DZ pseudopotentials for the cations are used in the calculations. The tautomerization paths of the nucleobases are investigated and transition states between the tautomeric forms of the free bases are located. The relative stability of the complexes and the tautomers of the free nucleobases are discussed referring to MIA and relative energy values. For uracil, thymine and adenine, interaction of the metal cations with the most stable tautomers form the least stable molecular complexes. For cytosine and guanine, the stability of the metalated complexes differs significantly. The enthalpy (ΔH), entropy (TΔS) and free energy (ΔG) of the complexes at 298 K have also been calculated.

  13. Atomic arrangement and electron band structure of Si(1 1 1)-ß-√3 x √3-Bi reconstruction modified by alkali-metal adsorption: ab initio study.

    Science.gov (United States)

    Eremeev, S V; Chukurov, E N; Gruznev, D V; Zotov, A V; Saranin, A A

    2015-08-01

    Using ab initio calculations, atomic structure and electronic properties of Si(1 1 1)[Formula: see text]-Bi surface modified by adsorption of 1/3 monolayer of alkali metals, Li, Na, K, Rb and Cs, have been explored. Upon adsorption of all metals, a similar atomic structure develops at the surface where twisted chained Bi trimers are arranged into a honeycomb network and alkali metal atoms occupy the [Formula: see text] sites in the center of each honeycomb unit. Among other structural characteristics, the greatest variation concerns the relative heights at which alkali metals reside with respect to Bi-trimer layer. Except for Li, the other metals reside higher than Bi layer and their heights increase with atomic number. All adsorbed surface structures display similar electron band structures of which the most essential feature is metallic surface-state band with a giant spin splitting. This electronic property allows one to consider the Si(1 1 1)[Formula: see text]-Bi surfaces modified by alkali metal adsorption as a set of material systems showing promise for spintronic applications. PMID:26151642

  14. Adsorption of humic acid by bi-functional resin JN-10 and the effect of alkali-earth metal ions on the adsorption

    International Nuclear Information System (INIS)

    This study investigated the adsorption of humic acid (HA) by bi-functional resin JN-10, which removed the HA more effectively than the commercial resins D-301, D-201, XAD-7, and globe active carbon F-400. The difference between the FT-IR spectroscopy and 13C NMR analysis of JN-10 before and after it adsorbing the HA revealed that both hydrophobic interaction and electric attraction were the adsorption force for the HA. The related thermodynamic parameters exhibited that the adsorption of the HA by JN-10 was an endothermic process. The occurring of adsorption was due to the increase of entropy, and the electric attraction was also a main adsorption force. In order to investigate the influence of the molecule weight (MW) of the HA on its removal by JN-10, the HA with the MWs ranging from 2000 to 100,000 Da was divided into six fractions by ultra-filtration. The HA with a medium MW (6000-10,000 Da) was preferentially removed by JN-10 due to the synergistic effect of hydrophilicity, molecular size, and aromaticity of the HA. The adsorption capacity of JN-10 for the HA increased in the presence of low concentration of alkali-earth metal ions Ca2+ and Mg2+, which neutralized the negative charges of the HA, but it decreased as the concentration of these ions increased because the hydrates formed by the alkali-earth metal ions occupied the adsorption sites of the resin.

  15. Crystal growth and evaluation of scintillation properties of Eu and alkali-metal co-doped LiSrAlF6 single crystals for thermal neutron detector

    International Nuclear Information System (INIS)

    In recent work, Na co-doping have found to improve the light output of Eu doped LiCaAlF6 (Eu:LiCAF) for thermal neutron scintillator. We grew Eu 2% and alkali metal 1% co-doped LiSAF crystals by Micro-Pulling down method to understand the effect of alkali metal co-doping on scintillation properties and mechanism compared with LiCAF. In photo- and α-ray induced radio-luminescence spectra of the all grown crystals, the emissions from d-f transition of Eu2+ were observed. Without relation to excitation source, decay times of co-doped LiSAF were longer than Eu only doped one. The light yield of Na, K and Cs co-doped LiSAF under 252Cf neutron excitation were improved. Especially, K co-doped Eu:LiSAF reached 33200 ph/n, which outperformed Eu only doped one by approximately 20% (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Institute of Scientific and Technical Information of China (English)

    陈平; 侯昭胤; 郑小明

    2005-01-01

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

  17. Rational design of carbonitrile-carboxaldehyde cation receptor models: probing the nature of the heteroatom-metal interaction.

    Science.gov (United States)

    Rosli, Ahmad Nazmi; Abu Bakar, Maizathul Akmam; Lee, Vannajan Sanghiran; Zain, Sharifuddin Md; Ahmad, Mohd Rais; Abdul Manan, Ninie Suhana; Alias, Yatimah; Woi, Pei Meng

    2014-09-01

    In this work, hybrid functional and G4 methods were employed in the rational design of carbonitrile-carboxaldehyde receptor models for cation recognition. Electron-sharing and ionic interactions between the models and the cations were analyzed utilizing the concepts of overlap population, atomic valence, electrostatic potential, and CHELPG charge in order to elucidate the nature of the heteroatom-metal interaction, the N versus O disparity, and the effect of pH. Receptor fragment models from ionomycin were employed to rationalize the selection of receptor models for discriminating group I cations and enhancing the selectivity for Mg(II) rather than Ca(II), and to examine the effects of keto-enol forms and negatively charged sites. The changes in geometries, overlap population, metal valence, and CHELPG charge upon solvation in heptane medium as compared to the gas phase were negligible. The optimized geometries reveal that the interaction between group II cations and the keto, enol, and enolate forms of 2-cyanoethanal causes 12 % bending of the C-C-N angle from linearity. Overlap populations show that the electron-sharing interaction favors group II cations but that the same mechanism allows Li(I) to compete. The total spin of Li(I) is 17 % greater than that of Ca(II), but the G4 binding energies of the two are separated by more than 50 kcal/mol, favoring group II cations, which may eliminate interference from Li(I). 1,2-Dicyanoethylene, which has only one form, shows similar characteristics. CHELPG analysis shows that Mg(II) transfers 25 and 18 % of its positive charge to 2-cyanoethanal enolate and 1,2-dicyanoethylene, respectively. Hydrogen atoms receive most of the positive charge in both receptors, but the N-termini exhibit strikingly different characteristics. Electrostatic potential contour profiles were found to be in good agreement with the atomic charge distributions. The application of uncharged 1,3-dicarbonyl and 2-cyanocarbonyl receptors and a judicious

  18. Complex formation in the system double charged metal cation-Stenhouse base in water-alcohol solution

    International Nuclear Information System (INIS)

    Using the method of potentiometric titration complex formation reaction of the system metal(II) salt cation (Me2+ = Fe2+, Cd2+, Hg2+, Zn2+, Mn2+, Co2+, Ni2+) Stenhouse base in water-alcohol solution has been studied. Compositions of equilibrium complexes, the constants of their formation and instability have been determined. CoCl2 x 6H2O, NiCl2 x 6H2O and Mn(NO3)2 x 6H2O have been shown to have the most stabilizing effect on Stenhouse base

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

    International Nuclear Information System (INIS)

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

  20. Correction to the Metal-Insulator Transition Temperature due to Cation Size and Strain Effects for Colossal Magnetoresistance Perovskites

    Institute of Scientific and Technical Information of China (English)

    袁松柳; 刘洁; 夏正才; 彭刚; 唐洁; 张国宏; 张力江; 冯文; 李衷怡; 杨应平; 刘莉; 熊曹水

    2002-01-01

    A phenomenological expression of the metal-insulator transition temperature is proposed for AMnO3 manganese perovskites by taking into account the distortion of the Mn-O-Mn bond due to A-cation size and the straindependent effect due to performed Jahn-Teller distortions, independently. Using reasonable physical parameters,the calculated results give excellent agreement with experimental data obtained in polycrystalline samples of La2/3 (Ca1-xBax)1/3MnO3, providing a strong support to this approach.

  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

    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...

  2. Novel fragmentation pathway for CID of (b(n) - 1 + Cat)+ ions from model, metal cationized peptides.

    Science.gov (United States)

    Cooper, Travis J; Talaty, Erach R; Van Stipdonk, Michael J

    2005-08-01

    We report a new fragmentation pathway for the CID of (b3 - 1 + Cat)+ product ions derived from the model peptide AXAG, where X = beta-alanine, gamma-aminobutyric acid, epsilon-amino-n-caproic acid, or 4-aminomethylbenzoic acid. By changing the amino acid to the C-terminal side of the amino acid X, and incorporating 15N and 13C labeled residues at the same position, we conclude that the dissociation pathway most likely leads to a metal cationized nitrile. With respect to the various amino acids at position X, the putative nitrile product becomes more prominent, relative to the conventional (a3 - 1 + Cat)+ species, in the order beta-alanine < gamma-aminobutyric acid < epsilon-aminocaproic acid < 4-aminomethylbenzoic acid. The pathway is not observed for peptides with alpha-amino acids at position X. The product ion is observed most prominently during the CID of Li+ and Na+ cationized peptides, only to a small extent for Ag+ cationized peptides, and not at all from protonated analogues. PMID:15990332

  3. Adsorption of volatile organic compounds in porous metal-organic frameworks functionalized by polyoxometalates

    International Nuclear Information System (INIS)

    The functionalization of porous metal-organic frameworks (Cu3(BTC)2) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N2 and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols (C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies estimated by the modified Clausius-Clapeyron equation provided insight into the impact of POMs and alkali metal cations on the adsorption of VOCs. The introduction of POMs not only improved the stability, but also brought the increase of adsorption capacity by strengthening the interaction with gas molecules. Furthermore, the exchanged alkali metal cations acted as active sites to interact with adsorbates and enhanced the adsorption of VOCs. - Graphical Abstract: The adsorption behavior of volatile organic compounds in porous metal-organic frameworks functionalized by polyoxometalates has been systematically evaluated. Highlights: → Functionalization of MOFs was achieved by incorporating Keggin-type POMs. → Introduction of POMs improved the thermal stability and adsorption capacity. → Alkali metal ion-exchange modified the inclusion state and also enhanced the adsorption. → Adsorption enthalpies were estimated to study the impact of POMs and alkali metal cations.

  4. Introduction of a cation in aqueous solution by electrolytic dissolution of metal. Applications to the decontamination of radioactive effluents

    International Nuclear Information System (INIS)

    This research thesis aims at comparing results obtained in chemical decontamination of radioactive effluents with a metallic cation introduced by metal electro-dissolution or by dose addition. After an overview of methods used for the purification of radioactive effluents and a more precise presentation of chemical co-precipitation, the author reports preliminary tests of the application of chemical co-precipitation to the decontamination of radioactive effluents, reports the analysis of iron, zinc and copper behaviour in aqueous environment by means of thermodynamic diagrams and current-voltage curves. He reports the design and use of two electro-dissolution sets, and the application of copper electrolytic dissolution to the elimination of ruthenium in radioactive effluents. He finally addresses the purification treatment of effluents of nuclear reactors

  5. Effect of Variations in Annealing Temperature and Metallic Cations on Nanostructured Molybdate Thin Films

    Directory of Open Access Journals (Sweden)

    Varela JoséArana

    2008-01-01

    Full Text Available AbstractCrystalline molybdate thin films were prepared by the complex polymerization method. The AMoO4(A = Ca, Sr, Ba films were deposited onto Si wafers by the spinning technique. The Mo–O bond in the AMoO4structure was confirmed by FTIR spectra. X-ray diffraction revealed the presence of crystalline scheelite-type phase. The mass, size, and basicity of A2+cations was found to be dependent on the intrinsic characteristics of the materials. The grain size increased in the following order: CaMoO4 < SrMoO4 < BaMoO4. The emission band wavelength was detected at around 576 nm. Our findings suggest that the material’s morphology and photoluminescence were both affected by the variations in cations (Ca, Sr, or Ba and in the thermal treatment.

  6. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Science.gov (United States)

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

    2012-07-01

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

  7. QED radiative corrections and many-body effects in atoms: the Uehling potential and shifts in alkali metals

    CERN Document Server

    Ginges, J S M

    2015-01-01

    We consider the largest (Uehling) contribution to the one-loop vacuum polarization correction to the binding energies in neutral alkali atoms, from Na through to the superheavy element E119. We use the relativistic Hartree-Fock method to demonstrate the importance of core relaxation effects. These effects are sizeable everywhere, though particularly important for orbitals with angular momentum quantum number l > 0. For d waves, the Uehling shift is enhanced by many orders of magnitude: for Cs the enhancement is more than four orders of magnitude and for the lighter alkali atoms it is even larger. We also study the effects of second- and higher-order many-body perturbation theory on the valence level shifts through inclusion of the correlation potential. The many-body enhancement mechanisms that operate in the case of the Uehling potential apply also to the case of the larger QED self-energy radiative corrections. The huge enhancement for d level shifts makes high-precision studies of transition frequencies in...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

  9. Improved thermoelectric performance in polycrystalline p-type Bi2Te3 via an alkali metal salt hydrothermal nanocoating treatment approach

    Science.gov (United States)

    Ji, Xiaohua; He, Jian; Su, Zhe; Gothard, Nick; Tritt, Terry M.

    2008-08-01

    We report herein a proof-of-principle study of grain boundary engineering in the polycrystalline p-type Bi2Te3 system. Utilizing the recently developed hydrothermal nanocoating treatment technique, we fabricated an alkali-metal(s)-containing surface layer on the p-Bi2Te3 bulk grain, which in turn became part of the grain boundary upon hot pressing densification. Compared to the untreated bulk reference, the dimensionless figure of merit ZT has been improved by ˜30% in the Na-treated sample chiefly due to the reduced thermal conductivity, and ˜38% in the Rb-treated sample mainly owing to the improved power factor. The grain boundary phase provides a new avenue by which one can potentially decouple the otherwise inter-related electrical resistivity, Seebeck coefficient, and thermal conductivity within one thermoelectric material.

  10. "XA6" octahedra influencing the arrangement of anionic groups and optical properties in inverse-perovskite [B6O10]XA3 (X = Cl, Br; A = alkali metal).

    Science.gov (United States)

    Yang, Zhihua; Lei, Bing-Hua; Yang, Bin; Pan, Shilie

    2016-06-01

    Exploring the effect of microscopic units, which set up the perovsikte framework, is of importance for material design. In this study, a series of borate halides with inverse-perovskite structures [B6O10]XA3 (X = Cl, Br; A = alkali metal) have been studied. It was revealed that the distortion and volume of XA6 octahedra influence the arrangement of anionic groups, which leads to the flexibility of the perovskite-related framework and differences in optical properties. Under the structural control scheme, the structure of Rb3B6O10Cl was predicted. The stability of the predicted structure was confirmed by an ab initio density functional theory-based method. The calculation shows Rb3B6O10Cl has a short UV cutoff edge of less than 200 nm, a moderate birefringence and a large second harmonic generation response. PMID:27211304

  11. Biotic ligand modeling approach: Synthesis of the effect of major cations on the toxicity of metals to soil and aquatic organisms.

    Science.gov (United States)

    Ardestani, Masoud M; van Straalen, Nico M; van Gestel, Cornelis A M

    2015-10-01

    The biotic ligand model (BLM) approach is used to assess metal toxicity, taking into account the competition of other cations with the free metal ions for binding to the biotic ligand sites of aquatic and soil organisms. The bioavailable fraction of metals, represented by the free metal ion, is a better measure than the total concentration for assessing their potential risk to the environment. Because BLMs are relating toxicity to the fraction of biotic ligands occupied by the metal, they can be useful for investigating factors affecting metal bioaccumulation and toxicity. In the present review, the effects of major cations on the toxicity of metals to soil and aquatic organisms were comprehensively studied by performing a meta-analysis of BLM literature data. Interactions at the binding sites were shown to be species- and metal-specific. The main factors affecting the relationships between toxicity and conditional binding constants for metal binding at the biotic ligand appeared to be Ca(2+) , Mg(2+) , and protons. Other important characteristics of the exposure medium, such as levels of dissolved organic carbon and concentrations of other cations, should also be considered to obtain a proper assessment of metal toxicity to soil and aquatic organisms. PMID:25953362

  12. The sorption of some heavy metal cations using A and P zeolites, synthesized from Iranian natural clinoptilolite and investigation of ionic interference effects on sorption

    International Nuclear Information System (INIS)

    Heavy metal cations exist in the industrial waste streams,fi.om factories and mines. Most of them are very toxic and harmful to human kind and its environment. In this research, removal of some cations from a simulated waste stream was investigated. Most of researches were investigated the removal of cations without presence of other cations. This paper intends to investigate the effect of the ionic interference on the heavy cations removal with synthetic zeolites A and P, which were synthesized from Iranian natural clinoptilolite. In this concern, effects of various parameters such as reaction time, temperature, and pH, concentration of the in going heavy metal cations (i.e. Pb2+, Zn2+, Cd2+ and Ni2+ ) as well as the effect of ionic interference were investigated. The results obtained from batch and column operations were shown that it is possible to reduce the concentration of these cations to an acceptable level based on the environmental standards, by using these zeolites

  13. Design study of a 200 MW(e) alkali metal/steam binary power plant using a coal-fired fluidized bed furnace

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, G.; Graves, R. L.; Lackey, M. E.; Tudor, J. J.; Zimmerman, G. P.

    1978-04-01

    The results of a study of 200 MW(e) alkali metal/steam binary power plant using a coal-fired fluidized bed furnace are described. Both cesium and potassium were evaluated for the topping cycle working fluid and cesium was selected. The fuel used was Illinois No. 6 coal, and limestone was used as the bed sorbent material. For the reference design, the furnace operated at atmospheric pressure and the cycle conditions for the power conversion system were 1500/sup 0/F to 900/sup 0/F for the topping cycle and 2400 psi 1000/sup 0/F to 1/sup 1///sub 2/ in. Hg for the steam system. Several variations of the plant were briefly evaluated. These variations included using a supercritical steam system and using a pressurized furnace. The principal conclusions of the study are as follows: a satisfactory design of an atmospheric pressure fluidized bed furnace binary power plant was evolved which uses a variation of the conventional binary cycle which permits utilizing the full potential of the alkali metal topping cycle; the net plant efficiency (coal to busbar) of the reference system was 44.6%; the net plant efficiency of a larger system with a 3500 psi 1000/sup 0/F steam system was 46.8%; an intermediate pressure turbocharged system with a furnace pressure of 4 atm (0.4 MPa) would have many advantages in comparison to the atmospheric pressure system, including a plant efficiency about one percentage point higher than the reference design, reduced limestone requirement and potential capital cost saving; and although cost estimates were not a part of the design study, a comparison of the design of this study to that of the Energy Conversion Alternative Study (ECAS) indicates plant costs 20 to 25% less than that of the final ECAS design.

  14. Reclamation of reactive metal oxides from complex minerals using alkali roasting and leaching- an improved approach to process engineering

    OpenAIRE

    Sanchez Segado, S; Makanyire, T; Escudero-Castejon, L; Hara, Y.; Jha, A.

    2015-01-01

    In nature, the commonly occurring reactive metal oxides of titanium, chromium, aluminium, and vanadium often chemically combine with the transition metal oxides such as iron oxides and form complex minerals. Physico-chemical separation of transition metal oxides from the remaining reactive metal oxides is therefore an important step in the purification of reactive oxide constituents. Each purification step has quite a high energy requirement at present. Current practice in industry yields sul...

  15. Influence of soil properties on heavy metal sequestration by biochar amendment: 1. Copper sorption isotherms and the release of cations.

    Science.gov (United States)

    Uchimiya, Minori; Klasson, K Thomas; Wartelle, Lynda H; Lima, Isabel M

    2011-03-01

    The amendment of carbonaceous materials such as biochars and activated carbons is a promising in situ remediation strategy for both organic and inorganic contaminants in soils and sediments. Mechanistic understandings in sorption of heavy metals on amended soil are necessary for appropriate selection and application of carbonaceous materials for heavy metal sequestration in specific soil types. In this study, copper sorption isotherms were obtained for soils having distinct characteristics: clay-rich, alkaline San Joaquin soil with significant heavy metal sorption capacity, and eroded, acidic Norfolk sandy loam soil having low capacity to retain copper. The amendment of acidic pecan shell-derived activated carbon and basic broiler litter biochar lead to a greater enhancement of copper sorption in Norfolk soil than in San Joaquin soil. In Norfolk soil, the amendment of acidic activated carbon enhanced copper sorption primarily via cation exchange mechanism, i.e., release of proton, calcium, and aluminum, while acid dissolution of aluminum cannot be ruled out. For San Joaquin soil, enhanced copper retention by biochar amendment likely resulted from the following additional mechanisms: electrostatic interactions between copper and negatively charged soil and biochar surfaces, sorption on mineral (ash) components, complexation of copper by surface functional groups and delocalized π electrons of carbonaceous materials, and precipitation. Influence of biochar on the release of additional elements (e.g., Al, Ca) must be carefully considered when used as a soil amendment to sequester heavy metals. PMID:21147495

  16. QED radiative corrections and many-body effects in atoms: vacuum polarization and binding energy shifts in alkali metals

    Science.gov (United States)

    Ginges, J. S. M.; Berengut, J. C.

    2016-05-01

    We calculate vacuum polarization corrections to the binding energies in neutral alkali atoms Na through to the superheavy element E119. We employ the relativistic Hartree–Fock method to demonstrate the importance of relaxation of the electronic core and the correlation potential method to study the effects of second and higher orders of perturbation theory. These many-body effects are sizeable for all orbitals, though particularly important for orbitals with angular momentum quantum number l\\gt 0. The orders of magnitude enhancement for d waves produces shifts that, for Rb and the heavier elements, are larger than those for p waves and only an order of magnitude smaller than the s-wave shifts. The many-body enhancement mechanisms that operate for vacuum polarization apply also to the larger self-energy corrections.

  17. Lifetime studies of high power rhodium/tungsten and molybdenum electrodes for application to AMTEC (alkali metal thermal-to-electric converter)

    International Nuclear Information System (INIS)

    The alkali metal thermoelectric converter (AMTEC) is a passive, direct energy conversion device potentially capable of near-Carnot efficiencies and demonstrated to perform to 19% efficiency and up to 1.0 W/cm2 power densities. It utilizes a high sodium activity gradient across a beta alumina solid electrolyte (BASE) and the properties of the porous metal electrode (PME) on the low pressure side of the electrolyte is critical to device performance. Sintering of the electrode, reaction between its constituents and BASE at their common interface, and metal migration within the electrode structure are all potential routes to long term degradation of electrode performance. Evaluation of these processes, which often may be measured at levels far below those affecting overall electrode performance, is necessary to construction of a valid lifetime performance model for AMTEC electrodes. Results of modeling with the limited available data indicate that thin Mo electrodes may show significant performance degradation for extended operation (>10,000 hrs) at higher operating temperatures (>1150K), while W/Rh and W/Pt electrodes are expected to show adequate performance at 1200K for lifetimes >10,000 hrs

  18. Structural phase stability, electronic structure and mechanical properties of alkali metal hydrides AMH4 (A=Li, Na; M=B, AL)

    Science.gov (United States)

    Santhosh, M.; Rajeswarapalanichamy, R.

    2016-01-01

    The structural stability of Alkali metal hydrides AMH4 (A=Li, Na; M=B, Al) is analyzed among the various crystal structures, namely hexagonal (P63mc), tetragonal (P42/nmc), tetragonal (P-421c), tetragonal (I41/a), orthorhombic (Pnma) and monoclinic (P21/c). It is observed that, orthorhombic (Pnma) phase is the most stable structure for LiBH4, monoclinic (P21/c) for LiAlH4, tetragonal (P42/nmc) for NaBH4 and tetragonal (I41/a) for NaAlH4 at normal pressure. Pressure induced structural phase transitions are observed in LiBH4, LiAlH4, NaBH4 and NaAlH4 at the pressures of 4 GPa, 36.1 GPa, 26.5 GPa and 46 GPa respectively. The electronic structure reveals that these metal hydrides are wide band gap insulators. The calculated elastic constants indicate that these metal hydrides are mechanically stable at normal pressure.

  19. Thermodynamic and structural properties of ball-milled mixtures composed of nano-structural graphite and alkali(-earth) metal hydride

    International Nuclear Information System (INIS)

    Hydrogen desorption properties of mechanically milled materials composed of nano-structural hydrogenated-graphite (CnanoH x) and alkali(-earth) metal hydride (MH; M = Na, Mg and Ca) were investigated from the thermodynamic and structural points of view. The hydrogen desorption temperature for all the CnanoH x and MH composites was obviously lower than that of the corresponding each hydride. In addition, the desorption of hydrocarbons from CnanoH x was significantly suppressed by making composite of CnanoH x with MH, even though CnanoH x itself thermally desorbs a considerably large amount of hydrocarbons. These results indicate that an interaction exists between CnanoH x and MH, and hydrogen in both the phases is destabilized by a close contact between polar C-H groups in CnanoH x and the MH solid phase. Moreover, a new type of chemical bonding between the nano-structural carbon (Cnano) and the Li, Ca, or Mg metal atoms may be formed after hydrogen desorption. Thus, the above metal-C-H system would be recognized as a new family of H-storage materials

  20. Effects of humic acid and competing cations on metal uptake by Lolium perenne

    NARCIS (Netherlands)

    Kalis, E.J.J.; Temminghoff, E.J.M.; Weng, L.P.; Riemsdijk, van W.H.

    2006-01-01

    Within the biotic ligand model, which describes relationships between chemical speciation and metal binding at an organism's surface, multicomponent (long-term) metal uptake by plants has seldom been studied. In the present work, we exposed perennial ryegrass to nutrient solutions with two levels of

  1. Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

    OpenAIRE

    Lammert, Heiko; Heuer, Andreas

    2005-01-01

    The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed--alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronge...

  2. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    International Nuclear Information System (INIS)

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

  3. Selective adsorption of cationic dyes from aqueous solution by polyoxometalate-based metal-organic framework composite

    Science.gov (United States)

    Liu, Xiaoxia; Gong, Wenpeng; Luo, Jing; Zou, Chentao; Yang, Yun; Yang, Shuijin

    2016-01-01

    A novel environmental friendly adsorbent H6P2W18O62/MOF-5 was synthesized by a simple one-step reaction under solvothermal conditions and characterized by XRD, FTIR, thermogravimetric analyses (TGA) and N2 adsorption-desorption isotherms. The removal rate of H6P2W18O62/MOF-5 was quite greater (85%) than that of MOF-5 (almost zero), showing that the adsorption performance of porous MOF-5 can be improved through the modification of H6P2W18O62. Further study revealed that H6P2W18O62/MOF-5 exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes in aqueous solution. The removal rate was up to 97% for cationic dyes methylene blue (MB) and 68% for rhodamine B(Rhb) within 10 min. However, anionicdye methyl orange(MO) can only reach to 10%. The influences including initial concentration, contact time, initial solution pH and temperature of MB adsorption onto H6P2W18O62/MOF-5 were investigated in detail. The kinetic study indicated that the adsorption of MB onto H6P2W18O62/MOF-5 followed the pseudo second-order model well. The isotherm obtained from experimental data fitted the Langmuir model, yielding maximum adsorption capacity of 51.81 mg/g. The thermodynamic parameters analysis illustrated that the MB adsorption onto H6P2W18O62 immobilized MOF-5 was spontaneous and endothermic process. Besides, these results implied that designing a novel material polyoxometalate-based metal-organic frameworks is great potential for removing cationic organic pollutants and even extended to improve other specific application.

  4. Metal ion complexation by ionizable crown ethers. Progress report, January 1, 1991--December 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1993-07-01

    Cyclic and acyclic polyether compounds with pendent carboxylic acid, phosphonic acid monoethyl ester, sulfonic acid, phosphinic acid and hydroxamic acid groups have been synthesized. The proton-ionizable polyethers can come with and without lipophilic groups. Two types of lipophilic di-ionizable lariat ethers have been prepared. Conformations of proton-ionizable lariat ethers have been probed. Competitive alkali metal cation transport by syn-(decyl)dibenzo-16-crown-5-oxyacetic acid and lipophilic proton-ionizable dibenzo lariat ethers in polymer-supported liquid membranes was studied. Complexation of alkali metal cations with ionized lariat ethers was studied. Condensation polymerization of cyclic and acyclic dibenzo polyethers containing pendent mono-ionizable groups with formaldehyde produces novel ion exchange resins with both ion exchange sites for metal ion complexation and polyether binding sites for metal ion recognition. Resins prepared from lariat ether dibenzo phosphonic acid monoethyl esters show strong sorption of divalent heavy metal cations with selectivity for Pb{sup 2+}.

  5. Understanding selectivity of hard and soft metal cations within biological systems using the subvalence concept. I. Application to blood coagulation: direct cation-protein electronic effects vs. indirect interactions through water networks

    Science.gov (United States)

    de Courcy, B.; Pedersen, L. G.; Parisel, O.; Gresh, N.; Silvi, B.; Pilmé, J.; Piquemal, J.-P.

    2010-01-01

    Following a previous study by de Courcy et al. ((2009) Interdiscip. Sci. Comput. Life Sci. 1, 55-60), we demonstrate in this contribution, using quantum chemistry, that metal cations exhibit a specific topological signature in the electron localization of their density interacting with ligands according to its “soft” or “hard” character. Introducing the concept of metal cation subvalence, we show that a metal cation can split its outer-shell density (the so-called subvalent domains or basins) according to it capability to form a partly covalent bond involving charge transfer. Such behaviour is investigated by means of several quantum chemical interpretative methods encompasing the topological analysis of the Electron Localization Function (ELF) and Bader's Quantum Theory of Atoms in Molecules (QTAIM) and two energy decomposition analyses (EDA), namely the Restricted Variational Space (RVS) and Constrained Space Orbital Variations (CSOV) approaches. Further rationalization is performed by computing ELF and QTAIM local properties such as electrostatic distributed moments and local chemical descriptors such as condensed Fukui Functions and dual descriptors. These reactivity indexes are computed within the ELF topological analysis in addition to QTAIM offering access to non atomic reactivity local index, for example on lone pairs. We apply this “subvalence” concept to study the cation selectivity in enzymes involved in blood coagulation (GLA domains of three coagulation factors). We show that the calcium ions are clearly able to form partially covalent charge transfer networks between the subdomain of the metal ion and the carboxylate oxygen lone pairs whereas magnesium does not have such ability. Our analysis also explains the different role of two groups (high affinity and low affinity cation binding sites) present in GLA domains. If the presence of Ca(II) is mandatory in the central “high affinity” region to conserve a proper folding and a charge

  6. Investigation of electrochemical intrusion of cations by the method of contact electric resistance

    International Nuclear Information System (INIS)

    Paper shows the possibility and prospects of application of contact electric resistance technique (CER) to study in-situ the initial stages of electrochemical admission of cations (ECA). ECA is shown to increase CER of metals. It enables to determine ECA potential and to investigate kinetics of this process. Using ECA in copper, silver and zinc from alkali solutions as an example one has shown that CER technique enables to obtain results that do not contradict well-known published data. Potentials of ECA cations from acid and neutral solutions in copper, platinum, iron, titanium and tungsten are determined

  7. New hypodiphosphates of the alkali metals: Synthesis, crystal structure and vibrational spectra of the hypodiphosphates(IV) M{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (M=Rb and Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Peng [Institut fuer Anorganische und Analytische Chemie der TU Clausthal, Paul-Ernst-Strasse 4, D-38678 Clausthal-Zellerfeld (Germany); Wiegand, Thomas; Eckert, Hellmut [Institut fuer Physikalische Chemie and Graduate School of Chemistry, Westfaelische Wilhelms-Universitaet Muenster, Corrensstr. 28/30, D-48149 Muenster (Germany); Gjikaj, Mimoza, E-mail: mimoza.gjikaj@tu-clausthal.de [Institut fuer Anorganische und Analytische Chemie der TU Clausthal, Paul-Ernst-Strasse 4, D-38678 Clausthal-Zellerfeld (Germany)

    2012-10-15

    The new hypodiphosphates(IV) Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (1) and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (2) were synthesized by soft chemistry reactions from aqueous solutions of hypophosphoric acid and the corresponding heavy alkali-metal carbonates. Their crystal structures were determined by single crystal X-ray diffraction. Both compounds crystallize isotypic in the triclinic space group P-1 with one formula unit in the unit cell. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units in staggered conformation for the P{sub 2}O{sub 6} skeleton and the corresponding alkali-metal cations. In the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} ion the hydrogen atoms are in a 'trans-trans' conformation. O{center_dot}H-O hydrogen bonds between the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups consolidate the structures into a three-dimensional network. The FT-Raman and {sup 31}P and {sup 1}H and MAS NMR spectra of the title compounds have been recorded and interpreted, especially with respect to their assignment to the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups. Thermogravimetric data of 2 have been interpreted in terms of a thermal decomposition model. - Graphical Abstract: The layered compounds Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] have been synthesized and investigated. Both crystallize isotypic. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units and the corresponding alkali-metal cations. Highlights: Black-Right-Pointing-Pointer Synthesis and single-crystal structure of new alkali hypodiphosphates. Black-Right-Pointing-Pointer Structures are characterized by [(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})]{sup 2-} units and M

  8. Model based multi-wavelength spectrophotometric method for calculation of formation constants of phenanthrenequinone thiosemicarbazone complexes with some metallic cations

    Directory of Open Access Journals (Sweden)

    Naser Samadi

    2013-04-01

    Full Text Available In traditional spectrophotometric determination of stability constants of complexation, it is necessary to find a wavelength at which only one of the components has absorbance without any spectroscopic interference of the other reaction components. In the present work, a simple multi-wavelength model-based method has been developed to determine stability constants for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components are extracted using multi-wavelength model based method. In the present work spectrophotometric titration of several cationic metal ions with new synthetic ligand were studied in order to calculate the formation constant(s. In order to estimate the formation constants a chemometrics method, model based analysis was applied.

  9. Morphology of sulfonated polyimide ionomers from ESR spectra of paramagnetic transition metal cations and nitroxide spin probes

    International Nuclear Information System (INIS)

    We present a study of sulfonated polyimide block ionomer membranes (SPIs) in the dry state, and swollen by water, methanol, ethanol, and dioxane. The ionomers are based on a naphthalenic dianhydride, and differ in the ionic exchange capacity and the type of diamine in the hydrophobic block. The ionomers were studied by electron spin resonance (ESR) spectroscopy of the paramagnetic transition metal cations Cu+ and VO2+, and of two nitroxide spin probes. The results indicated the existence of separate hydrophobic and hydrophilic domains in the dry and in the swollen membranes. Water clusters with a diameter + or K+. The irreversible increase of the signal intensity upon heating of the dry membranes above 360 K suggests the formation of reactive intermediates that may be involved in ionomer degradation processes. (author)

  10. Stabilizing effect of divalent metallic cations on membranes against thermal and gamma-irradiation damages

    International Nuclear Information System (INIS)

    Heat treatment of 270C and onward modifies the beet root cell membranes, resulting in the efflux of betacyanin from the tissue slices. No further efflux of betacyanin is observed when tissue slices taken in different sets are heated at a temperature of 450C for different intervals of time, 30, 60 and 90 min each and then transferred to 250 +- 20C, showing thereby that the temperature damage of the membrane is reversible. But if tissue slices are heated for longer durations at 450C, it is noticed that the membranes undergo a plastic strain. Divalent cations, Ca2+, Mg2+, Zn2+ and Pb2+ have been observed to inhibit the heat induced efflux of betacyanin. Also γ-irradiation of these tissue slices altered the membrane permeability and it is seen that calcium ions have a stabilizing effect on membranes against γ-irradiation damage. (author)

  11. Metal cation sensing material based on the assembly of meso-terakis(4-N,N,N-trimethylamiophenyl) porphyrin and mesoporous molecular sieve MCM-41

    Institute of Scientific and Technical Information of China (English)

    ZHANG Huidong; SUN Yinghui; ZHANG Ping; YE Kaiqi; ZHANG Jingying; WANG Yue

    2005-01-01

    The metal cation sensing material was prepared by entrapment of a water-soluble porphyrin compound, mesoterakis(4-N,N,N-trimethylamiophenyl) porphyrin (TTMAPP), in mesoporous molecular sieve MCM-41. The powder X-ray diffraction (XRD) spectra results demonstrated that after the introduction of TTMAPP, the ordered channel arrangement of MCM-41 remained. The assembly material, TTMAPP/MCM-41, exhibited a typical absorption feature of porphyrin compound. Emission spectrum study revealed that the introduction of zinc (II) cation resulted in the formation of a new emission peak at 600 nm for TTMAPP/MCM-41, while the presence of copper (II) cation at low concentration led to that the luminescent intensity of TTMAPP/MCM-41 was obviously reduced by 68.42%. The experiment results demonstrated that TTMAPP/MCM-41 is a cation sensing materials with good performance.

  12. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    International Nuclear Information System (INIS)

    In this paper, we systematically investigate the electronic structure for the 2Σ+ ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained

  13. Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells

    Science.gov (United States)

    Altamura, Giovanni; Wang, Mingqing; Choy, Kwang-Leong

    2016-02-01

    Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1-xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber|buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells.

  14. Theoretical study on the ground state of the polar alkali-metal-barium molecules: potential energy curve and permanent dipole moment.

    Science.gov (United States)

    Gou, Dezhi; Kuang, Xiaoyu; Gao, Yufeng; Huo, Dongming

    2015-01-21

    In this paper, we systematically investigate the electronic structure for the (2)Σ(+) ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained. PMID:25612710

  15. Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Dezhi; Kuang, Xiaoyu, E-mail: scu-kuang@163.com; Gao, Yufeng; Huo, Dongming [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)

    2015-01-21

    In this paper, we systematically investigate the electronic structure for the {sup 2}Σ{sup +} ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained.

  16. Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells.

    Science.gov (United States)

    Altamura, Giovanni; Wang, Mingqing; Choy, Kwang-Leong

    2016-01-01

    Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1-xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber(|)buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells. PMID:26916212

  17. Towards new molecular superconductors: a first study of alkali metal reduced aromatic cryptands as 'pseudo-fullerides'

    International Nuclear Information System (INIS)

    The search for new molecular superconductors based upon concepts derived from the interpretation of alkali fullerides superconductivity led to the study of an aromatic cryptand (IHIC) considered as 'pseudo-fullerene'. New solids made of IHIC mono or di-reduced by potassium, rubidium and cesium were investigated. Low field microwave absorption (LFMA) signals appeared at 20 K for IHIC-Rb and IHIC-K (1:1), although these observations could not be confirmed by AC susceptibility or SQUID magnetometry. IR spectroscopy was used to probe the integrity of the final solid. EPR spectra consisted of a single symmetric line, combination of a Gaussian and of a Lorentzian lineshape, down to 4.2 K. However, the paramagnetic contribution of the reduced molecular species was too high to allow the observation of any transition at low temperature. Although two samples had a semiconductor like conductivity behavior as a function of temperature at high temperature, no indication of the presence of conduction electrons could be observed on the EPR spectrum. The LFMA measurements obtained can be considered as hints of superconductivity, thus opening the route towards new materials. (orig.)

  18. New electrolyte systems for capillary zone electrophoresis of metal cations and non-ionic organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Y.

    1995-06-19

    Excellent separations of metal ions can be obtained very quickly by capillary electrophoresis provided a weak complexing reagent is incorporated into the electrolyte to alter the effective mobilities of the sample ions. Indirect photometric detection is possible by also adding a UV-sensitive ion to the electrolyte. Separations are described using phthalate, tartrate, lactate or hydroxyisobutyrate as the complexing reagent. A separation of twenty-seven metal ions was achieved in only 6 min using a lactate system. A mechanism for the separation of lanthanides is proposed for the hydroxyisobutyrate system.

  19. Calcined Ternary Layered Double Hydroxides Containing Transition Metal Cations as Highly Active VOC Oxidation Catalysts

    Czech Academy of Sciences Publication Activity Database

    Jirátová, Květa; Kovanda, F.; Ludvíková, Jana; Klempa, Jan

    - : -, 2015 - (Giordano, G.; Perathoner, S.; Marchese, L.), s. 143-144 ISBN N. [Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis /6:/. Amantea (IT), 14.07.2015-17.07.2015] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : VOC oxidation * transition metal oxides * ethanol Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  20. Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

    Science.gov (United States)

    Tawfik, Salah M; Hefni, Hassan H

    2016-01-01

    New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant. PMID:26478092

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  3. Calcined Ternary Layered Double Hydroxides Containing Transition Metal Cations as Highly Active VOC Oxidation Catalysts

    Czech Academy of Sciences Publication Activity Database

    Jirátová, Květa; Kovanda, F.; Ludvíková, Jana; Klempa, Jan

    -: -, 2015 - (Giordano, G.; Perathoner, S.; Marchese, L.), s. 143-144 ISBN N. [Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis /6:/. Amantea (IT), 14.07.2015-17.07.2015] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : VOC oxidation * transition metal oxides * ethanol Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  4. A combined experimental and quantum mechanical investigation on some selected metal complexes of L-serine with first row transition metal cations

    Science.gov (United States)

    Mandal, Shilpi; Das, Gunajyoti; Askari, Hassan

    2015-02-01

    In the current study a joint solvent-free synthetic and computational approach has been adopted to explore the coordination properties of L-serine with the doubly charged cations of nickel, copper and zinc. The reaction products were characterized by elemental analyses, molar conductance, EDAX-SEM, TEM, TG/DTA, infrared, electronic absorption and fluorescence spectroscopy. Quantum chemical calculations, carried out in gas and aqueous phase using the BHandHLYP and MP2 methods in conjunction with 6-311++G(d,p) basis set, provide valuable insights concerning the interaction enthalpies and free energies; vibrational and absorption spectra along with various other molecular and electronic properties of the metal complexes. This study reveals that L-serine binds to the metal ions in a bi-dentate manner through its amino and carboxylate groups exhibiting highest binding affinity towards Cu(II) among the three metal ions considered here. As compared to the MP2 method, the spin-delocalized situations of the open-shell Cu(II) complex of L-serine have been better described at the BHandHLYP level. The physical origin of the molecular interactions of L-serine with the metal ions has also been examined by performing energy decomposition analysis (EDA). Effects of the aqueous environment are evident on the structure and stability of the metal complexes. The vibrational spectroscopic data furnished at MP2/6-311++G(d,p) level, which provide a good account of the structural changes inflicted in the molecular geometry of L-serine as a result of metal coordination, are in better agreement with our experimental observations as compared to those produced at the BHandHLYP/6-311++G(d,p) level.

  5. TOLERANCE OF AGAVE TEQUILANA TO HIGH LEVELS OF DIVALENT METAL CATIONS

    Directory of Open Access Journals (Sweden)

    Elmi Roseida Cen-Cen

    2015-11-01

    Full Text Available Los agaves son plantas que pertenecen a un género constituido por numerosas especies, adaptadas para crecer en muy diversos hábitats, algunos con condiciones ambientales extremas. Distintas especies de agave crecen sobre distintos tipos de suelos, algunas en suelos con muy bajo contenido de nutrientes minerales y otras en suelos salinos o en suelos contaminados con iones metálicos. La relación planta-suelo ha sido escasamente estudiada en este género por lo que se desconoce, entre otras cuestiones, cuál es la capacidad de los agaves para absorber, transportar y almacenar nutrientes minerales, cuáles son los mecanismos celulares y bioquímicos que utilizan, o si poseen especial sensibilidad o tolerancia a los iones metálicos. Este estudio reporta el efecto de diversas concentraciones de sulfato de cadmio, cobalto, cobre, zinc o de manganeso sobre plántulas deAgave tequilana, bajo condiciones controladas de laboratorio; la concentración mínima de esos iones metálicos requerida para inducir un efecto tóxico visualmente detectable en tiempos cortos (ocho días; describimos los efectos tóxicos que estos metales generan sobre las plántulas de agave; y reportamos la cantidad de Cu2+, Cd2+ y Co2+ que se acumula en las hojas de plántulas de agave tratadas con altas concentraciones (milimolares de esos metales. Nuestros resultados muestran que, en experimentos de toxicidad aguda y bajo las condiciones aquí establecidas, elA. tequilanaposee una notable tolerancia a altas concentraciones de los distintos metales iónicos probados, incluyendo tanto micronutrientes como metales tóxicos, así como la capacidad de transportar en altas cantidades estos metales a tejido aéreo.

  6. Ceruloplasmin revisited: structural and functional roles of various metal cation-binding sites

    International Nuclear Information System (INIS)

    The three-dimensional molecular structure of human serum ceruloplasmin has been reinvestigated using X-ray synchrotron data collected at 100 K from a crystal frozen to liquid-nitrogen temperature. The three-dimensional molecular structure of human serum ceruloplasmin has been reinvestigated using X-ray synchrotron data collected at 100 K from a crystal frozen to liquid-nitrogen temperature. The resulting model, with an increase in resolution from 3.1 to 2.8 Å, gives an overall improvement of the molecular structure, in particular the side chains. In addition, it enables the clear definition of previously unidentified Ca2+-binding and Na+-binding sites. The Ca2+ cation is located in domain 1 in a configuration very similar to that found in the activated bovine factor Va. The Na+ sites appear to play a structural role in providing rigidity to the three protuberances on the top surface of the molecule. These features probably help to steer substrates towards the mononuclear copper sites prior to their oxidation and to restrict the size of the approaching substrate. The trinuclear copper centre appears to differ from the room-temperature structure in that a dioxygen moiety is bound in a similar way to that found in the endospore coat protein CotA from Bacillus subtilis

  7. Fluorescence properties of riboflavin-functionalized mesoporous silica SBA-15 and riboflavin solutions in presence of different metal and organic cations

    Science.gov (United States)

    Lewandowski, Dawid; Schroeder, Grzegorz; Sawczak, Mirosław; Ossowski, Tadeusz

    2015-10-01

    Riboflavin was covalently linked to mesoporous SBA-15 silica surface via grafting technique. Then fluorescence properties of the system obtained were analyzed in the presence of several metal and organic cations. Both quenching and strengthening of fluorescence as well as significant changes in the maximum fluorescence wavelength were observed. The results were compared with absorption and fluorescence data obtained for riboflavin water solutions.

  8. Binding energy referencing for XPS in alkali metal-based battery materials research (I): Basic model investigations

    International Nuclear Information System (INIS)

    Highlights: • We point to a not seriously solved conflict in energy scale referencing of Li metal samples in XPS. • Model experiments at Li-, Na-metal and Li-doped HOPG samples were used to classify the effects. • Binding energy shifts up to 3 eV are observed when the alkaline metal is present in metallic state. • A phenomenological explanation based on an electrostatic interaction is suggested. • Consequences for energy scale correction depending on the kind of surface species are followed. - Abstract: For the investigation of chemical changes in Li- and Na-ion battery electrode systems, X-ray photoelectron spectroscopy (XPS) is a well-accepted method. Charge compensation and referencing of the binding energy (BE) scale is necessary to account for the involved mostly non-conducting species. Motivated by a conflict in energy scale referencing of Li-metal samples discussed earlier by several authors, further clarifying experimental results on several Li containing reference materials are presented and extended by similar experiments for Na. When correlating the peak positions of characteristic chemical species in all the different prepared model sample states, there seems to be a systematic deviation in characteristic binding energies of several eV if lithium is present in its metallic state. Similar results were found for sodium. The observations are furthermore confirmed by the implementation of inert artificial energy reference material, such as implanted argon or deposited gold. The behavior is associated with the high reactivity of metallic lithium and a phenomenological explanation is proposed for the understanding of the observations. Consequences for data interpretation in Li-ion battery research will be discussed for various applications in part (II)

  9. Binding energy referencing for XPS in alkali metal-based battery materials research (I): Basic model investigations

    Energy Technology Data Exchange (ETDEWEB)

    Oswald, S., E-mail: s.oswald@ifw-dresden.de

    2015-10-01

    Highlights: • We point to a not seriously solved conflict in energy scale referencing of Li metal samples in XPS. • Model experiments at Li-, Na-metal and Li-doped HOPG samples were used to classify the effects. • Binding energy shifts up to 3 eV are observed when the alkaline metal is present in metallic state. • A phenomenological explanation based on an electrostatic interaction is suggested. • Consequences for energy scale correction depending on the kind of surface species are followed. - Abstract: For the investigation of chemical changes in Li- and Na-ion battery electrode systems, X-ray photoelectron spectroscopy (XPS) is a well-accepted method. Charge compensation and referencing of the binding energy (BE) scale is necessary to account for the involved mostly non-conducting species. Motivated by a conflict in energy scale referencing of Li-metal samples discussed earlier by several authors, further clarifying experimental results on several Li containing reference materials are presented and extended by similar experiments for Na. When correlating the peak positions of characteristic chemical species in all the different prepared model sample states, there seems to be a systematic deviation in characteristic binding energies of several eV if lithium is present in its metallic state. Similar results were found for sodium. The observations are furthermore confirmed by the implementation of inert artificial energy reference material, such as implanted argon or deposited gold. The behavior is associated with the high reactivity of metallic lithium and a phenomenological explanation is proposed for the understanding of the observations. Consequences for data interpretation in Li-ion battery research will be discussed for various applications in part (II)

  10. Experimental and theoretical determinations of the absolute ionization cross section of alkali metals by electron impact in the energy range from 100 to 2000 eV

    International Nuclear Information System (INIS)

    The absolute electron impact ionization cross sections for the alkali metals in the energy range between 100 eV and 2000 eV were measured by the non-modulated crossed beam technique. The neutral beam of alkali atoms is produced by a Knudsen cell and crossed at right angles with the electron beam. The ions formed are collected on a plate and their intensity determined with a D.C. amplifier. The neutral beam is condensed on a cold trap cooled with liquid nitrogen, this temperature being much lower than that required to obtain total condensation. The amount of metal deposited is measured by the isotopic dilution technique and by atomic absorption, and the density of the atoms in the neutral beam is calculated. The total absolute ionization cross sections can then be determined. All possible errors have been carefully analyzed and their magnitudes estimated. The absolute ionization cross section for Li at an energy of 500 eV is: QLi = 0,358 x 10-16 cm2. This value is half of that obtained by Mac Farland and Kinney. The partial ionization cross sections for the singly and multiply charged ions is determined with a mass spectrometer attached to this apparatus. For the singly charged ions, the variation of the cross section with the energy of the ionizing electrons is in agreement with the optically allowed transition law: Q = A log BE/E. From the variation of Q with E, the squared matrix elements of the transition moment (|Mi|)2 are determined for all the elements studied. New calculations of the ionization cross section of Li and Na were performed in the framework of the Born-Bethe approximation as modified by Gaudin and Botter to take into account collisions with large momentum variation of the incident electron. Hartree-Fock type wave functions for the ground state atom (tabulated by Clementi) were used. The calculated values are in good agreement with our experimental results and with the former theoretical results calculated by various methods. This work also

  11. Synthesis and chemistry of cationic d{sup 0} metal alkyl complexes. Progress report, July 1988--May 1991

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, R.F.

    1991-12-31

    The objective of this project is to develop new types of electrophilic metal alkyl complexes for catalytic C-H activation and olefin polymerization chemistry, and associated fundamental mechanistic studies. We have focused our efforts on four classes of early metal alkyl complexes: (1) cationic group 4 Cp{sub 2}M(R){sup +} complexes (1) which are active species in Cp{sub 2}MX{sub 2}-based Ziegler-Natta olefin polymerization catalyst systems and which catalyze productive C-H activation reactions of heterocycles, (2) neutral (dicarbollide)(Cp*)M(R) complexes (2) which are structurally are electronically very similar to 1, (3) half-sandwich complexes CpM(R){sub 2}(L){sub n}{sup +} which are highly coordinatively and electronically unsaturated, and (4) new group 5 (dicarbollide)(Cp)MR{sub 2} and (dicarbollide){sub 2} MR complexes which are more unsaturated than group 5 Cp{sub 2}M systems due to incorporation of the dicarbollide ligand.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1987-06-01

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

  14. Diode laser spectroscopy of NaD, KD, RbD, and CsD: determination of the mass independent parameters and mass scaling coefficients of the alkali metal hydrides

    International Nuclear Information System (INIS)

    The infrared spectrum of the monodeuterides of the alkali metals, sodium, potassium, rubidium, and cesium have been measured with a nominal accuracy of ±0.001 cm-1 using a diode laser spectrometer. Spectral lines of both the fundamental and the first hot band were observed for all the deuterides except RbD where only the fundamental was measured. The accuracy of previously published data on KH was also improved. Combination of these new data with similar results obtained previously for the equivalent monohydrides allowed the determination of a set of mass-independent parameters and mass-scaling coefficients for the hydrides of all of the alkali metals. This has allowed the relative magnitudes of the parameters to be compared for the first time. The results indicate that non-adiabatic effects are most prevalent in CsH. (orig.)

  15. Synergistic extraction of transition metal cations from aqueous media by two separated organic phases

    International Nuclear Information System (INIS)

    We have therefore initiated novel approaches to the study of the mechanism of the synergistic extraction of metal ions by means of two separated organic phases, which are brought in contact with the same aqueous phase. The present work is concerned with the extraction of transition metals and actinides ions from nitric acid by chelating agents e.g., HTTA thenoyltrifluoroacetone in a diluent - the first organic phase, and by natural donor, e.g., TBP, tri-butyl phosphate in a diluent the second organic phase. The adduct formation was studied by means of spectrochemical and radiochemical methods. In the first approach the aqueous phase was attacked with both organic phases simultanously (the static or parallel extraction). In this method organic phase are separated one from the other. It was shown that even in the absence of mixing, synergism is observed under this experimental conditions. The results indicate, that adduct formation occurs in both organic phases. Nevertheless the enhanchment of extraction in the TBP phase is by far greater than that in the HTTA containing phase. This approach has one disadvatage, viz., the experiments are very time consuming, a typical experiment requiring over 10 days. In order to overcome this difficulty, the following experiments were carried out: the aqueous phase were first shaken with diluent containing an anionic ligand and the phases were allowed to separate. Then the aqueous solution were shaken with diluent containing a netural donor and the phase again were allowed to separate. The concentration of the metal ions in all the phases were determined. The experiments were repeated with an other diluent replacing the first diluent in one or both organic phases. In this way eight sequences of experiments were carried out for each concentration set chosen. The results thus point out that this experimental approach open new possibilities to investigate the mechanism and the kinetics of synergistic extraction processes. (author) the

  16. Stripping potentiometric analysis: application to determination of metallic cations in presence of uranium

    International Nuclear Information System (INIS)

    Potentiometric stripping analysis consists of a potentiostatic deposition step of trace elements and a subsequent stripping step. The trace metals are simultaneously reduced at a rotating electrode, the working electrode being a mercury film coated glassy carbon electrode; the amalgamated metals are then re-oxidized with an oxidizing agent. The analytical signal of this method is the time required for complete re-oxidation. Influence of different parameters on the analytical signal is studied by using mercury (II) ions as oxidizing agent in 5.10-4 M H2SO4 aqueous solution. Here, we point out the main characteristics of the potentiometric stripping analysis under the same experimental conditions. The reproductibility ranges are comprised between 0.5% to 1.5% and the detection limit for cadmium (II) is estimated to be 2.10-10 M with a plating time of 300 seconds. Small quantities, as 10-7 M Cd2+, Pb2+ and Zn2+ are simultaneously determined in presence of U (VI) ions (UO22+) with an accuracy of 0.5% for Cd2+ and Zn2+, and 4.5% for Pb2+. Compared to well-known electrochemical techniques, potentiometric stripping analysis appears to be a performing method for trace analysis in a wide range of media: this method permits the analysis of elements in presence of species more concentrated and being able to oxidize the trace elements

  17. Synthesis and spectral characterization of a new blue fluorescent tripod for detecting metal cations and protons

    Energy Technology Data Exchange (ETDEWEB)

    Staneva, Desislava [University of Chemical Technology and Metallurgy, 1756 Sofia (Bulgaria); Makki, Mohammad S.I.; Sobahi, Tariq R. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Bosch, Paula [Institute of Science and Technology of Polymers, CSIC, Juan de la Cierva 3, 28006, Madrid (Spain); Abdel-Rahman, Reda M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Asiri, Abdullah [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Grabchev, Ivo, E-mail: i.grabchev@chem.uni-sofia.bg [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Sofia University “St. Kliment Ohridski”, Faculty of Medicine, 1407 Sofia (Bulgaria)

    2015-06-15

    A new symmetrical blue fluorescent tripod containing three 1,8-naphtalimide fragments has been synthesized. Its spectral properties have been investigated in organic solvents of different polarity. Its basic photophysical characteristics depend strongly on the polarity of the organic solvents. In nonpolar solvents (diethyl ether, chloroform and toluene) the new tripod emits eximer fluorescence. The new tripod has been investigated as a ligand for detection of metal ions (Ag{sup +}, Co{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Ni{sup 2+}, and Cu{sup 2+}) in acetonitrile and acetonitrile/H{sub 2}O (1:4, v/v). The influence of protons in an ethanol–water (1:4, v/v) solution and in toluene and diethyl ether solvents on the tripod fluorescence intensity has been investigated and it has been shown that the protons destroy the excimer formations recovering the monomer fluorescence. - Highlights: • New blue fluorescent tripod containing three 1,8-naphtalimide fragments was described. • In nonpolar solvents the new tripod emits eximer fluorescence. • The new tripod has been investigated as a ligand for metal ions and protons.

  18. Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

    Science.gov (United States)

    Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

    2016-06-01

    The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions. PMID:26856546

  19. Efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated ITO substrate and an electron-injection layer of alkali-metal carbonates

    International Nuclear Information System (INIS)

    The efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated substrate and an electron-injection layer of alkali-metal carbonates (Li2CO3 and Cs2CO3) was studied. The Li2CO3 and the Cs2CO3 carbonates were thermally evaporated to a thickness of 1 nm. For the device with a Li2CO3 layer, the luminance at 9.25 V of the device with the plasma-treated ITO substrate was found to be improved by approximately 10% compared to that of the device with the plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.0 V. For the device with a Cs2CO3 layer, the luminance at 11.25 V of the device with the oxygen plasma-treated ITO substrate was found to be improved by approximately 42.3% compared to that of the device with plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.25 V. Especially, the luminous efficiencies of the devices with the Li2CO3 and the Cs2CO3 layers were confirmed to have been increased by 50.0% and 78.1%, respectively, when the oxygen-plasma-treated ITO substrate was used.

  20. Effect of Siloxane Ring Strain and Cation Charge Density on the Formation of Coordinately Unsaturated Metal Sites on Silica: Insights from DFT Studies

    Energy Technology Data Exchange (ETDEWEB)

    Das, Ujjal; Zhang, Guanghui; Hu, Bo; Hock, Adam S.; Redfern, Paul C.; Miller, Jeffrey T.; Curtiss, Larry A.

    2015-12-01

    Amorphous silica (SiO2) is commonly used as a support in heterogeneous catalysis. However, due to the structural disorder and temperature induced change of surface morphology, the structures of silica supported metal catalysts are difficult to determine. Most studies are primarily focused on understanding the interactions of different types of surface hydroxyl groups with metal ions. In comparison, the effect of siloxane ring size on the structure of silica supported metal catalysts and how it affects catalytic activity is poorly understood. Here, we have used density functional theory calculations to understand the effect of siloxane ring strain on structure and activity of different monomeric Lewis acid metal sites on silica. In particular, we have found that large siloxane rings favor strong dative bonding interaction between metal ion and surface hydroxyls, leading to the formation of high-coordinate metal sites. In comparison, metal-silanol interaction is weak in small siloxane rings, resulting in low-coordinate metal sites. The physical origin of this size dependence is associated with siloxane ring strain, and, a correlation between metal-silanol interaction energy and ring strain energy has been observed. In addition to ring strain, the strength of the metal-silanol interaction also depends on the positive charge density of the cations. In fact, a correlation also exists between metal-silanol interaction energy and charge density of several first-row transition and post-transition metals. The theoretical results are compared with the EXAFS data of monomeric Zn(II) and Ga(III) ions grafted on silica. The molecular level insights of how metal ion coordination on silica depends on siloxane ring strain and cation charge density will be useful in the synthesis of new catalysts.