WorldWideScience

Sample records for alkali metal ions

  1. 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.

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

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2008-01-01

    . 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 anion DBS...

  3. Process for carbonaceous material conversion and recovery of alkali metal catalyst constituents held by ion exchange sites in conversion residue

    Science.gov (United States)

    Sharp, David W.

    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 for the particles by contacting or washing them with an aqueous solution containing calcium or magnesium ions in an alkali metal recovery zone at a low temperature, preferably below about 249.degree. F. During the washing or leaching process, the calcium or magnesium ions displace alkali metal ions held by ion exchange sites in the particles thereby liberating the ions and producing an aqueous effluent containing alkali metal constituents. The aqueous effluent from the alkali metal recovery zone 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.

  4. Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

    Institute of Scientific and Technical Information of China (English)

    AN Hai-Long; LIU Yu-Zhi; ZHANG Su-Hua; ZHAN Yong; ZHANG Hai-Lin

    2008-01-01

    The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-311G basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.

  5. A negative ion source for alkali ions

    NARCIS (Netherlands)

    Vermeer, A.; Zwol, N.A. van

    1980-01-01

    An ion source is described which delivers negative alkali ions. With this source, which consists of a duoplasmatron and a charge exchange canal with alkali vapour, negative Li, Na and K ions are produced. The oven in which alkali metals are evaporated can reach temperatures up to 575°C.

  6. Synthetic, structural, and theoretical investigations of alkali metal germanium hydrides--contact molecules and separated ions.

    Science.gov (United States)

    Teng, Weijie; Allis, Damian G; Ruhlandt-Senge, Karin

    2007-01-01

    The preparation of a series of crown ether ligated alkali metal (M=K, Rb, Cs) germyl derivatives M(crown ether)nGeH3 through the hydrolysis of the respective tris(trimethylsilyl)germanides is reported. Depending on the alkali metal and the crown ether diameter, the hydrides display either contact molecules or separated ions in the solid state, providing a unique structural insight into the geometry of the obscure GeH3- ion. Germyl derivatives displaying M--Ge bonds in the solid state are of the general formula [M([18]crown-6)(thf)GeH3] with M=K (1) and M=Rb (4). The compounds display an unexpected geometry with two of the GeH3 hydrogen atoms closely approaching the metal center, resulting in a partially inverted structure. Interestingly, the lone pair at germanium is not pointed towards the alkali metal, rather two of the three hydrides are approaching the alkali metal center to display M--H interactions. Separated ions display alkali metal cations bound to two crown ethers in a sandwich-type arrangement and non-coordinated GeH3- ions to afford complexes of the type [M(crown ether)2][GeH3] with M=K, crown ether=[15]crown-5 (2); M=K, crown ether=[12]crown-4 (3); and M=Cs, crown ether=[18]crown-6 (5). The highly reactive germyl derivatives were characterized by using X-ray crystallography, 1H and 13C NMR, and IR spectroscopy. Density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2) calculations were performed to analyze the geometry of the GeH3- ion in the contact molecules 1 and 4.

  7. Speciation of phytate ion in aqueous solution. Alkali metal complex formation in different ionic media.

    Science.gov (United States)

    De Stefano, Concetta; Milea, Demetrio; Pettignano, Alberto; Sammartano, Silvio

    2003-08-01

    The acid-base properties of phytic acid [ myo-inositol 1,2,3,4,5,6-hexakis(dihydrogen phosphate)] (H(12)Phy; Phy(12-)=phytate anion) were studied in aqueous solution by potentiometric measurements ([H+]-glass electrode) in lithium and potassium chloride aqueous media at different ionic strengths (0iodide (Et(4)NI; e.g., at I=0.5 mol L(-1), log K(3)(H)=11.7, 8.0, 9.1, and 9.1 in Et(4)NI, LiCl, NaCl and KCl, respectively; the protonation constants in Et(4)NI and NaCl were already reported), owing to the strong interactions occurring between the phytate and alkaline cations present in the background salt. We explained this in terms of complex formation between phytate and alkali metal ions. Experimental evidence allows us to consider the formation of 13 mixed proton-metal-ligand complexes, M(j)H(i)Phy((12-i-j)-), (M+ =Li+, Na+, K+), with jstability of alkali metal complexes follows the trend Li+ > or =Na+K+. Some measurements were also performed at constant ionic strength (I=0.5 mol L(-1)), using different mixtures of Et(4)NI and alkali metal chlorides, in order to confirm the formation of hypothesized and calculated metal-proton-ligand complex species and to obtain conditional protonation constants in these multi-component ionic media.

  8. Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard; Alvare, Javier

    2016-10-25

    Alkali metals and sulfur may be recovered from alkali monosulfide and polysulfides in an electrolytic process that utilizes an electrolytic cell having an alkali ion conductive membrane. An anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof and a solvent that dissolves elemental sulfur. A catholyte includes molten alkali metal. Applying an electric current oxidizes sulfide and polysulfide in the anolyte compartment, causes alkali metal ions to pass through the alkali ion conductive membrane to the catholyte compartment, and reduces the alkali metal ions in the catholyte compartment. Liquid sulfur separates from the anolyte solution and may be recovered. The electrolytic cell is operated at a temperature where the formed alkali metal and sulfur are molten.

  9. Catalysis by alkali and alkaline-earth metal ions in nucleophilic attack of methoxide ion on crown ethers bearing an intra-annular acetoxy group

    NARCIS (Netherlands)

    Cacciapaglia, Roberta; Lucente, Silvia; Mandolini, Luigi; Doorn, van Arie R.; Reinhoudt, David N.; Verboom, Willem

    1989-01-01

    Rates of reaction of methoxide ion with crown ethers bearing an intra-annular acetoxy group are markedly enhanced by alkali and alkaline-earth metal bromides as a result of much stronger interactions of the metal ions with transition states than with reactants. Rates of reactions of methoxide ion w

  10. 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

  11. 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

    2016-06-06

    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.

  12. 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

    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...

  13. UV and IR spectroscopy of cold 1,2-dimethoxybenzene complexes with alkali metal ions.

    Science.gov (United States)

    Inokuchi, Yoshiya; Boyarkin, Oleg V; Ebata, Takayuki; Rizzo, Thomas R

    2012-04-01

    We report UV photodissociation (UVPD) and IR-UV double-resonance spectra of 1,2-dimethoxybenzene (DMB) complexes with alkali metal ions, M(+)·DMB (M = Li, Na, K, Rb, and Cs), in a cold, 22-pole ion trap. The UVPD spectrum of the Li(+) complex shows a strong origin band. For the K(+)·DMB, Rb(+)·DMB, and Cs(+)·DMB complexes, the origin band is very weak and low-frequency progressions are much more extensive than that of the Li(+) ion. In the case of the Na(+)·DMB complex, spectral features are similar to those of the K(+), Rb(+), and Cs(+) complexes, but vibronic bands are not resolved. Geometry optimization with density functional theory indicates that the metal ions are bonded to the oxygen atoms in all the M(+)·DMB complexes. For the Li(+) complex in the S(0) state, the Li(+) ion is located in the same plane as the benzene ring, while the Na(+), K(+), Rb(+), and Cs(+) ions are located off the plane. In the S(1) state, the Li(+) complex has a structure similar to that in the S(0) state, providing the strong origin band in the UV spectrum. In contrast, the other complexes show a large structural change in the out-of-plane direction upon S(1)-S(0) excitation, which results in the extensive low-frequency progressions in the UVPD spectra. For the Na(+)·DMB complex, fast charge transfer occurs from Na(+) to DMB after the UV excitation, making the bandwidth of the UVPD spectrum much broader than that of the other complexes and producing the photofragment DMB(+) ion.

  14. Difference of coordination between alkali- and alkaline-earth-metal ions to a symmetrical α,α',δ,δ'-tetramethylcucurbit[6]uril.

    Science.gov (United States)

    Chen, Wen-Jian; Yu, Da-Hai; Xiao, Xin; Zhang, Yun-Qian; Zhu, Qian-Jiang; Xue, Sai-Feng; Tao, Zhu; Wei, Gang

    2011-08-01

    To explore differences in coordination between alkali- and alkaline-earth-metal ions and cucurbit[n]urils, a water-soluble α,α',δ,δ'-tetramethylcucurbit[6]uril (TMeQ[6]) was used to synthesize a series of complexes and their supramolecular assemblies, based on the coordination of TMeQ[6] with alkali- and alkaline-earth-metal ions. The complexes and corresponding supramolecular assemblies were structurally characterized by single-crystal X-ray diffraction. Unlike cucurbituril (Q[6]), which formed the metal-Q[6] polymers based on the direct coordination of carbonyl oxygen atoms to the alkali-metal ions, TMeQ[6] formed metal-TMeQ[6] polymers based on the direct coordination of carbonyl oxygen atoms with the alkaline-earth-metal ions rather than the alkali-metal ions.

  15. Characterization of Adsorbed Alkali Metal Ions in 2:1 Type Clay Minerals from First-Principles Metadynamics.

    Science.gov (United States)

    Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi

    2015-07-30

    Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two-dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs(+) in the 2:1 type trioctahedral clay minerals with saponite-like compositions, where lighter alkali metal ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs(+) is found to result partially from the capability of recognizing selectively Cs(+) ions at the basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.

  16. New class of scorpionate: tris(tetrazolyl)-iron complex and its different coordination modes for alkali metal ions.

    Science.gov (United States)

    Park, Ka Hyun; Lee, Kang Mun; Go, Min Jeong; Choi, Sung Ho; Park, Hyoung-Ryun; Kim, Youngjo; Lee, Junseong

    2014-08-18

    We report formation of a new metallascorpionate ligand, [FeL3](3-) (IPtz), containing a Fe core and three 5-(2-hydroxyphenyl)-1H-tetrazole (LH2) ligands. It features two different binding sites, oxygen and nitrogen triangles, which consist of three oxygen or nitrogen donors from tetrazole. The binding affinities of the complex for three alkali metal ions were studied using UV spectrophotometry titrations. All three alkali metal ions show high affinities and binding constants (>3 × 10(6) M(-1)), based on the 1:1 binding isotherms to IPtz. The coordination modes of the alkali metals and IPtz in the solid were studied using X-ray crystallography; two different electron-donor sites show different coordination numbers for Li(+), Na(+), and K(+) ions. The oxygen triangles have the κ(2) coordination mode with Li(+) and κ(3) coordination mode with Na(+) and K(+) ions, whereas the nitrogen triangles show κ(3) coordination with K(+) only. The different binding affinities of IPtz in the solid were manipulated using multiple metal precursors. A Fe-K-Zn trimetallic complex was constructed by assembly of an IPtz ligand, K, and Zn precursors and characterized using X-ray crystallography. Oxygen donors are coordinated with the K ion via the κ(3) coordination mode, and nitrogen donors are coordinated with Zn metal by κ(3) coordination. The solid-state structure was confirmed to be a honeycomb coordination polymer with a one-dimensional infinite metallic array, i.e., -(K-K-Fe-Zn-Fe-K)n-.

  17. Synthesis and exchange properties of sulfonated poly(phenylene sulfide) with alkali metal ions in organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Son, Won Keun [Chungnam National Univ., Taejon (Korea, Republic of); Kim, Sang Hern [Taejon National Univ., Taejon (Korea, Republic of); Park, Soo Gil [Chungbuk National Univ., Cheongju (Korea, Republic of)

    2001-01-01

    Sulfonated poly(phenylene sulfide) (SPPS) polymers were prepared by sulfonation of poly[methyl[4-(phenylthio)phenyl] sulfonium trifluoromethanesulfonate] (PPST) with fumic sulfonic acid (10% SO{sub 3}-H{sub 2}SO{sub 4}) and demethylation with aqueous NaOH solution. The equilibrium constants of ion exchange reactions between alkali metal cations (Li{sup +}, Na{sup +}, and K{sup +}) and SPPS ion exchanger in organic solvents such as in organic solvents such as tetrahydrofuran (THF) and dioxane were measured. The equilibrium constants of ion exchange reactions increased as the polarity of the solvent increased, and the reaction temperature decreased. The equilibrium constants of the ion exchange reaction (K{sub eq}) also increased in the order of Li{sup +}, Na{sup +}, and K{sup +}. To elucidate the spontaneity of the exchange reaction in organic solvents, the enthalpy, entropy, and Gibbs free energy were calculated. The enthalpy of reaction ranged from -0.88 to -1.33 kcal/mol, entropy ranged from 1.42 to 4.41 cal/Kmol, and Gibbs free energy ranged from -1.03 to -2.55 kcal/mol. Therefore, the exchange reactions were spontaneous because the Gibbs free energies were negative. The SPPS ion exchanger and alkali metal ion bounding each other produced good ion exchange capability in organic solvents.

  18. 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).

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

    Science.gov (United States)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-13

    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 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 Ca(2+), Li(+), Na(+), NH4(+)) at concentrations up to 25 mM. This material can be combined further with disposable chips, demonstrating its promise as an effective ion-selective sensing component for practical applications.

  20. Upgrading platform using alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard

    2017-01-17

    A method for removing sulfur, nitrogen or metals from an oil feedstock. 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.

  1. Upgrading platform using alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

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

  3. 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.

  4. Partial alkali-metal ion extraction from K0.8(Li0.27Ti1.73)O4 using PTFE as an extraction reagent.

    Science.gov (United States)

    Ozawa, Tadashi C; Sasaki, Takayoshi

    2014-10-21

    The alkali-metal ion extraction ability of an inert material, polytetrafluoroethylene (PTFE; empirical formula CF2), was clarified by characterizing a partially alkali-metal ion-extracted layered compound, K0.8(Li0.27Ti1.73)O4. Washing K0.8(Li0.27Ti1.73)O4 in water extracts only 44% of the interlayer K(+) and no intralayer Li(+); on the other hand, 53% of the interlayer K(+) and approximately 10% of the intralayer Li(+) ions were extracted from K0.8(Li0.27Ti1.73)O4 by the reaction with PTFE at 350 °C under flowing Ar. A systematic decrease in the lattice parameters a and c along the intralayer directions and an increase in b along the interlayer direction were observed, consistent with the alkali-metal ion deintercalation amount as a function of the reaction temperatures and the reacted PTFE amounts. After the reaction with K0.8(Li0.27Ti1.73)O4 : CF2 = 1 : 0.6 in mol, the lattice parameter b increased to 1.5607(3) nm from 1.5522(2) of the pristine K0.8(Li0.27Ti1.73)O4, and this change in the lattice parameter was approximately one order of magnitude larger than those in a and c.

  5. Study of structural and spectroscopic behavior of Sm3+ ions in lead-zinc borate glasses containing alkali metal ions

    Science.gov (United States)

    Sasi Kumar, M. V.; Babu, S.; Rajeswara Reddy, B.; Ratnakaram, Y. C.

    2017-02-01

    High luminescence behavior of rare earth inorganic glasses have a variety of uses in the industry. In the past few decades, rare earth ions with characteristic photonics applications are being hosted by heavy metal oxide glasses. Among the rare earth ions Sm3+ ion has features which make it apt for high density optical storage. The authors of the paper have experimented to synthesize Sm3+ doped glasses. In this regard a new series of borate glasses doped with 1 mol% Sm3+ ion are developed by using melt-quenching technique. XRD, FTIR, optical absorption, luminescence techniques are used to study the various characteristics of Sm3+ ion in the present glass matrices. The XRD spectra confirms the amorphous nature of glasses. Further, the researchers have used differential thermal analysis to study the glass transition temperature. The structural groups in the prepared glasses are studied using Fourier transform infrared spectra. From the measurement of its optical absorption, three phenomenological Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) have been computed. Based on these Judd-Ofelt intensity parameters, radiative properties such as radiative probabilities (Arad), branching ratios (β), and radiative life time (τR) are calculated. The excitation spectra of Sm3+ doped lithium heavy metal borate glass matrix is recorded under the emission wavelength of 600 nm. The emission spectra are recorded under 404 nm excitation wavelength. From various emission transitions, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 bands could be of interest for various applications. The decay profiles of 4G5/2 level exhibit single exponential nature in all the prepared glass matrices. The potassium glass matrix exhibits higher quantum efficiency than the other glass matrices. Finally, by going through these several spectroscopic characterizations, it is concluded that the prepared Sm3+ doped lead-zinc borate glasses might be useful for visible light applications.

  6. Cation-π interaction of alkali metal ions with C24 fullerene: a DFT study.

    Science.gov (United States)

    Moradi, Morteza; Peyghan, Ali Ahmadi; Bagheri, Zargham; Kamfiroozi, Mohammad

    2012-08-01

    Using first principle calculations, we investigated cation-π interactions between alkali cations (Li(+), Na(+), and K(+)) and pristine C(24) or doped fullerenes of BC(23), and NC(23). The most suitable adsorption site is found to be atop the center of a six-membered ring of the exterior surface of C(24) molecule. Interaction energies of these cations decreased in the order: Li(+) > Na(+) > K(+), with values of -31.82, -22.36, and -15.68 kcal mol(-1), respectively. It was shown that the interaction energies are increased and decreased by impurity doping of B and N atoms in adjacent wall of adsorption site, depending on electron donating or receptivity of the doping atoms.

  7. Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent.

    Science.gov (United States)

    Liu, Yong-Qiang; Yu, Hong

    2016-08-01

    Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded.

  8. 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

    , 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...... of the number of M+ ions entering the film, and therefore the inserted M+ mass. The mass of the water molecules can then be calculated as a difference. The values determined this way may be called membrane hydration numbers. The results yield the following membrane hydration numbers: Li+: 5.3-5.5; Na+ 4...... membrane....

  9. Generation and characterization of alkali metal clusters in Y-FAU zeolites. An ESR and MAS NMR spectroscopic study

    Science.gov (United States)

    Hannus, István; Béres, Attila; Nagy, János B.; Halász, János; Kiricsi, Imre

    1997-06-01

    Charged and neutral metal clusters of various compositions and sizes can be prepared by controlling the alkali metal content by the decomposition of alkali azides and the composition of the host zeolite by ion-exchange. ESR signals show that electron transfer from alkali metal atoms to alkali metal cations does occur, but in a direction opposite to that predicted by the gas-phase thermochemistry. Alkali metal clusters proved to be very active basic catalytic centers.

  10. Size-specific interaction of alkali metal ions in the solvation of M+-benzene clusters by Ar atoms.

    Science.gov (United States)

    Huarte-Larrañaga, F; Aguilar, A; Lucas, J M; Albertí, M

    2007-08-23

    The size-specific influence of the M+ alkali ion (M = Li, Na, K, Rb, and Cs) in the solvation process of the M+-benzene clusters by Ar atoms is investigated by means of molecular dynamic simulations. To fully understand the behavior observed in M+-bz-Ar(n) clusters, solvation is also studied in clusters containing either M+ or benzene only. The potential energy surfaces employed are based on a semiempirical bond-atom decomposition, which has been developed previously by some of the authors. The outcome of the dynamics is analyzed by employing radial distribution functions, studying the evolution of the distances between the Ar atoms and the alkali ion M+ or the benzene molecule for all M+-bz-Ar(n) clusters. For all members, in the M+-bz series, the benzene molecule (bz) is found to remain strongly bound to M+ even in the presence of solvent atoms. The radial distribution functions for the heavier clusters (K+-bz, Rb+-bz, and Cs+-bz), are found to be different than for the lighter (Na+-bz and Li+-bz) ones.

  11. Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post-source decay matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Kéki, S; Deák, G; Zsuga, M

    2001-12-01

    A post-source decay matrix-assisted laser desorption/ionization mass spectrometric (PSD-MALDI-MS) study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, is reported. The fragmentations of rutin were performed by selecting the [R + Cat]+ peaks for PSD, where R represents a rutin molecule and Cat an alkali metal ion (Li+, Na+, K+). The PSD-MALDI mass spectra showed, depending on Cat, different fragmentation patterns with respect to both the quality and quantity of the fragment ions formed. The intensity of fragmentation decreased in the order Li+ > Na+ > K+. The fragmentation mechanism and an explanation for the observed differences are suggested.

  12. 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.

  13. 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.

  14. Nanosized alkali-metal-doped ethoxotitanate clusters.

    Science.gov (United States)

    Chen, Yang; Trzop, Elzbieta; Makal, Anna; Sokolow, Jesse D; Coppens, Philip

    2013-05-06

    The synthesis and crystallographic characterization of alkali-metal-doped ethoxotitanate clusters with 28 and 29 Ti atoms as well as a new dopant-free Ti28 cluster are presented. The light-metal-doped polyoxotitanate clusters in which the alkali-metal atom is the critical structure-determining component are the largest synthesized so far. Calculations show that doping with light alkali atoms narrows the band gap compared with the nondoped crystals but does not introduce additional energy levels within the band gap.

  15. Alkali metal ion catalysis and inhibition in nucleophilic displacement reactions at phosphorus centers: ethyl and methyl paraoxon and ethyl and methyl parathion.

    Science.gov (United States)

    Um, Ik-Hwan; Shin, Young-Hee; Lee, Seung-Eun; Yang, Kiyull; Buncel, Erwin

    2008-02-01

    We report on the ethanolysis of the P=O and P=S compounds ethyl and methyl paraoxon (1a and 1b) and ethyl and methyl parathion (2a and 2b). Plots of spectrophotometrically measured rate constants, kobsd versus [MOEt], the alkali ethoxide concentration, show distinct upward and downward curvatures, pointing to the importance of ion-pairing phenomena and a differential reactivity of free ions and ion pairs. Three types of reactivity and selectivity patterns have been discerned: (1) For the P=O compounds 1a and 1b, LiOEt > NaOEt > KOEt > EtO-; (2) for the P=S compound 2a, KOEt > EtO- > NaOEt > LiOEt; (3) for P=S, 2b, 18C6-crown-complexed KOEt > KOEt = EtO(-) > NaOEt > LiOEt. These selectivity patterns are characteristic of both catalysis and inhibition by alkali-metal cations depending on the nature of the electrophilic center, P=O vs P=S, and the metal cation. Ground-state (GS) vs transition-state (TS) stabilization energies shed light on the catalytic and inhibitory tendencies. The unprecedented catalytic behavior of crowned-K(+) for the reaction of 2b is noteworthy. Modeling reveals an extreme steric interaction for the reaction of 2a with crowned-K(+), which is responsible for the absence of catalysis in this system. Overall, P=O exhibits greater reactivity than P=S, increasing from 50- to 60-fold with free EtO(-) and up to 2000-fold with LiOEt, reflecting an intrinsic P=O vs P=S reactivity difference (thio effect). The origin of reactivity and selectivity differences in these systems is discussed on the basis of competing electrostatic effects and solvational requirements as function of anionic electric field strength and cation size (Eisenman's theory).

  16. Formation of alkali-metal nanoparticles in alkali-silicate glasses under electron irradiation and thermal processing

    Science.gov (United States)

    Bochkareva, E. S.; Sidorov, A. I.; Ignat'ev, A. I.; Nikonorov, N. V.; Podsvirov, O. A.

    2017-02-01

    Experiments and numerical simulation show that the irradiation of alkali-containing glasses using electrons at an energy of 35 keV and the subsequent thermal processing at a temperature above the vitrification point lead to the formation of spherical metal (lithium, sodium, and potassium) nanoparticles with oxide sheaths that exhibit plasmon resonances in the visible spectral range. Glasses containing two alkali metals exhibit mutual effect of metals on the formation of nanoparticles with two compositions due to the difference of ion radii and mobilities of metal ions.

  17. Ion Pairing in Alkali Nitrate Electrolyte Solutions.

    Science.gov (United States)

    Xie, Wen Jun; Zhang, Zhen; Gao, Yi Qin

    2016-03-10

    In this study, we investigate the thermodynamics of alkali nitrate salt solutions, especially the formation of contact ion pairs between alkali cation and nitrate anion. The ion-pairing propensity shows an order of LiNO3 activity coefficients and suggest that the empirical "law of matching water affinity" is followed by these alkali nitrate salt solutions. The spatial patterns of contact ion pairs are different in the three salt solutions studied here: Li(+) forms the contact ion pair with only one oxygen of the nitrate while Na(+) and K(+) can also be shared by two oxygens of the nitrate. In reproducing the salt activity coefficient using Kirkwood-Buff theory, we find that it is essential to include electronic polarization for Li(+) which has a high charge density. The electronic continuum correction for nonpolarizable force field significantly improves the agreement between the calculated activity coefficients and their experimental values. This approach also improves the performance of the force field on salt solubility. From these two aspects, this study suggests that electronic continuum correction can be a promising approach to force-field development for ions with high charge densities.

  18. 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.

  19. Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sellaiyan, S.; Uedono, A. [University of Tsukuba, Division of Applied Physics, Tsukuba, Ibaraki (Japan); Sivaji, K.; Janet Priscilla, S. [University of Madras, Department of Nuclear Physics, Chennai (India); Sivasankari, J. [Anna University, Department of Physics, Chennai (India); Selvalakshmi, T. [National Institute of Technology, Nanomaterials Laboratory, Department of Physics, Tiruchirappalli (India)

    2016-10-15

    Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F{sub 2} {sup 2+} and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F{sub 2} {sup 2+} to F{sup +} and this F{sup +} is converted into F centers at 416 nm. (orig.)

  20. Controllable formation of heterotrimetallic coordination compounds: systematically incorporating lanthanide and alkali metal ions into the manganese 12-metallacrown-4 framework.

    Science.gov (United States)

    Azar, Michael R; Boron, Thaddeus T; Lutter, Jacob C; Daly, Connor I; Zegalia, Kelcie A; Nimthong, Ruthairat; Ferrence, Gregory M; Zeller, Matthias; Kampf, Jeff W; Pecoraro, Vincent L; Zaleski, Curtis M

    2014-02-01

    The inclusion of Ln(III) ions into the 12-MC-4 framework generates the first heterotrimetallic complexes of this molecular class. The controllable and deliberate preparations of these compounds are demonstrated through 12 crystal structures of the Ln(III)M(I)(OAc)4[12-MCMn(III)(N)shi-4](H2O)4·6DMF complex, where OAc(-) is acetate, shi(3-) is salicylhydroximate, and DMF is N,N-dimethylformamide. Compounds 1-12 have M(I) as Na(I), and Ln(III) can be Pr(III) (1), Nd(III) (2), Sm(III) (3), Eu(III) (4), Gd(III) (5), Tb(III) (6), Dy(III) (7), Ho(III) (8), Er(III) (9), Tm(III) (10), Yb(III) (11), and Y(III) (12). An example with M(I) = K(I) and Ln(III) = Dy(III) is also reported (Dy(III)K(OAc)4[12-MCMn(III)(N)shi-4](DMF)4·DMF (14)). When La(III), Ce(III), or Lu(III) is used as the Ln(III) ions to prepare the Ln(III)Na(I)(OAc)4[12-MCMn(III)(N)shi-4] complex, the compound Na2(OAc)2[12-MCMn(III)(N)shi-4](DMF)6·2DMF·1.60H2O (13) results. For compounds 1-12, the identity of the Ln(III) ion affects the 12-MCMn(III)(N)shi-4 framework as the largest Ln(III), Pr(III), causes an expansion of the 12-MCMn(III)(N)shi-4 framework as demonstrated by the largest metallacrown cavity radius (0.58 Å for 1 to 0.54 Å for 11), and the Pr(III) causes the 12-MCMn(III)(N)shi-4 framework to be the most domed structure as evident in the largest average angle about the axial coordination of the ring Mn(III) ions (103.95° for 1 to 101.69° for 11). For 14, the substitution of K(I) for Na(I) does not significantly affect the 12-MCMn(III)(N)shi-4 framework as many of the structural parameters such as the metallacrown cavity radius (0.56 Å) fall within the range of compounds 1-12. However, the use of the larger K(I) ion does cause the 12-MCMn(III)(N)shi-4 framework to become more planar as evident in a smaller average angle about the axial coordination of the ring Mn(III) ions (101.35°) compared to the analogous Dy(III)/Na(I) (7) complex (102.40°). In addition to broadening the range of

  1. Alkali-metal azides interacting with metal-organic frameworks.

    Science.gov (United States)

    Armata, Nerina; Cortese, Remedios; Duca, Dario; Triolo, Roberto

    2013-01-14

    Interactions between alkali-metal azides and metal-organic framework (MOF) derivatives, namely, the first and third members of the isoreticular MOF (IRMOF) family, IRMOF-1 and IRMOF-3, are studied within the density functional theory (DFT) paradigm. The investigations take into account different models of the selected IRMOFs. The mutual influence between the alkali-metal azides and the π rings or Zn centers of the involved MOF derivatives are studied by considering the interactions both of the alkali-metal cations with model aromatic centers and of the alkali-metal azides with distinct sites of differently sized models of IRMOF-1 and IRMOF-3. Several exchange and correlation functionals are employed to calculate the corresponding interaction energies. Remarkably, it is found that, with increasing alkali-metal atom size, the latter decrease for cations interacting with the π-ring systems and increase for the azides interacting with the MOF fragments. The opposite behavior is explained by stabilization effects on the azide moieties and determined by the Zn atoms, which constitute the inorganic vertices of the IRMOF species. Larger cations can, in fact, coordinate more efficiently to both the aromatic center and the azide anion, and thus stabilizing bridging arrangements of the azide between one alkali-metal and two Zn atoms in an η(2) coordination mode are more favored.

  2. 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.

  3. Competitive binding exchange between alkali metal ions (K+, Rb+, and Cs+) and Na+ ions bound to the dimeric quadruplex [d(G4T4G4)]2: a 23Na and 1H NMR study.

    Science.gov (United States)

    Cesare Marincola, Flaminia; Virno, Ada; Randazzo, Antonio; Mocci, Francesca; Saba, Giuseppe; Lai, Adolfo

    2009-12-01

    A comparative study of the competitive cation exchange between the alkali metal ions K+, Rb+, and Cs+ and the Na+ ions bound to the dimeric quadruplex [d(G4T4G4)]2 was performed in aqueous solution by a combined use of the 23Na and 1H NMR spectroscopy. The titration data confirm the different binding affinities of these ions for the G-quadruplex and, in particular, major differences in the behavior of Cs+ as compared to the other ions were found. Accordingly, Cs+ competes with Na+ only for the binding sites at the quadruplex surface (primarily phosphate groups), while K+ and Rb+ are also able to replace sodium ions located inside the quadruplex. Furthermore, the 1H NMR results relative to the CsCl titration evidence a close approach of Cs+ ions to the phosphate groups in the narrow groove of [d(G4T4G4)]2. Based on a three-site exchange model, the 23Na NMR relaxation data lead to an estimate of the relative binding affinity of Cs+ versus Na+ for the quadruplex surface of 0.5 at 298 K. Comparing this value to those reported in the literature for the surface of the G-quadruplex formed by 5'-guanosinemonophosphate and for the surface of double-helical DNA suggests that topology factors may have an important influence on the cation affinity for the phosphate groups on DNA.

  4. Removal of Retired Alkali Metal Test Systems

    Energy Technology Data Exchange (ETDEWEB)

    Brehm, W. F.; Church, W. R.; Biglin, J. W.

    2003-02-26

    This paper describes the successful effort to remove alkali metals, alkali metal residues, and piping and structures from retired non-radioactive test systems on the Hanford Site. These test systems were used between 1965 and 1982 to support the Fast Flux Test Facility and the Liquid Metal Fast Breeder Reactor Program. A considerable volume of sodium and sodium-potassium alloy (NaK) was successfully recycled to the commercial sector; structural material and electrical material such as wiring was also recycled. Innovative techniques were used to safely remove NaK and its residues from a test system that could not be gravity-drained. The work was done safely, with no environmental issues or significant schedule delays.

  5. Precision measurements of cross sections of inelastic processes realized in collisions of alkali metal ions with atoms of rare gases

    CERN Document Server

    Lomsadze, R A; Mosulishvili, N O; Kezerashvili, R Ya

    2015-01-01

    This work presents a multifaceted experimental study of collisions of Na$^{+}$ and K$^{+}$ ions in the energy range 0.5 -- 10 keV with He and Ar atoms. Absolute cross sections for charge-exchange, ionization, stripping and excitation were measured using a refined version of the transfer electric field method, angle- and energy-dependent collection of product ions, energy loss, and optical spectroscopy. The experimental data and the schematic correlation diagrams have been employed to analyze and determine the mechanisms for these processes.

  6. Precision measurements of cross-sections for inelastic processes in collisions of alkali metal ions with atoms of rare gases

    Science.gov (United States)

    Lomsadze, R. A.; Gochitashvili, M. R.; Kezerashvili, R. Ya.

    2017-01-01

    A multifaceted experimental study of collisions of Na+ and K+ ions in the energy range of 0.5-10 keV with He and Ar atoms is presented. Absolute cross-sections for charge-exchange, ionization, stripping and excitation processes were measured using a refined version of the transfer electric field method, angle- and energy-dependent collection of product ions, energy loss and optical spectroscopy methods. The experimental data and the schematic correlation diagrams are employed to analyze and determine the mechanisms for these processes.

  7. sup 29 Si magic angle spinning NMR spectra of alkali metal, alkaline earth metal, and rare earth metal ion exchanged Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Kueijung; Chern, Jeryoung (Tsinghua Univ., Taiwan (China))

    1989-02-23

    The variation of the extraframework cation location in groups IA and IIA metals and rare earth metal (RE) Y zeolites as a function of the dehydration and the rehydration is monitored by {sup 29}Si MAS NMR. Unheated hydrated zeolites give similar {sup 29}Si spectra as they present the similar cation distributions. Upon dehydration a high-field shift is observed which correlates with the distortion of bond angles in silicon-oxygen tetrahedra. The line shapes of {sup 29}Si spectra depend on the nature and the location of the exchangeable cations and the occupancy of the different sites in dehydrated and rehydrated states. The correlation between the line shape of {sup 29}Si spectra and the migration of cations from the supercages to the sodalite cages after heating treatment was studied. The results of {sup 29}Si NMR agree with the known structure data.

  8. [Development of metal ions analysis by ion chromatography].

    Science.gov (United States)

    Yu, Hong; Wang, Yuxin

    2007-05-01

    Analysis of metal ions by ion chromatography, including cation-exchange ion chromatography, anion-exchange ion chromatography and chelation ion chromatography, is reviewed. The cation-exchange ion chromatography is a main method for the determination of metal ions. Stationary phases in cation-exchange ion chromatography are strong acid cation exchanger (sulfonic) and weak acid cation exchanger (carboxylic). Alkali metal ions, alkaline earth metal ions, transition metal ions, rare earth metal ions, ammonium ions and amines can be analyzed by cation-exchange ion chromatography with a suitable detector. The anion-exchange ion chromatography is suitable for the separation and analysis of alkaline earth metal ions, transition metal ions and rare earth metal ions. The selectivity for analysis of metal ions with anion-exchange ion chromatography is good. Simultaneous determination of metal ions and inorganic anions can be achieved using anion-exchange ion chromatography. Chelation ion chromatography is suitable for the determination of trace metal ions in complex matrices. A total of 125 references are cited.

  9. Heterometallic aluminates: alkali metals trapped by an aluminium aryloxide claw.

    Science.gov (United States)

    Muñoz, M Teresa; Cuenca, Tomás; Mosquera, Marta E G

    2014-10-14

    A series of heterometallic aluminium-alkali metal species [AlMMe2{2,6-(MeO)2C6H3O}2]n have been isolated for lithium, sodium and potassium. These compounds can be generated by the reaction of [AlMe2{2,6-(MeO)2C6H3O}]2 with the metallated phenol [M{2,6-(MeO)2C6H3O}]n or through the reaction of the mixture of AlMe3 and the appropriate alkali metal alkyl base with two equivalents of 2,6-dimethoxyphenol. In the heterometallic species obtained, the {AlMe2{2,6-(MeO)2C6H3O}2}(-) moiety is observed and could be described as a claw which fixes the alkali ion by the phenoxide oxygen atoms while the methoxy groups help to stabilize their coordination sphere. All compounds have been characterized by NMR spectroscopy and X-ray diffraction methods. Catalytic studies reveal that these compounds are active in ring-opening polymerization of L-lactide.

  10. Device and method for upgrading petroleum feedstocks and petroleum refinery streams using an alkali metal conductive membrane

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard; Alvare, Javier

    2016-09-13

    A reactor has two chambers, namely an oil feedstock chamber and a source chamber. An ion separator separates the oil feedstock chamber from the source chamber, wherein the ion separator allows alkali metal ions to pass from the source chamber, through the ion separator, and into the oil feedstock chamber. A cathode is at least partially housed within the oil feedstock chamber and an anode is at least partially housed within the source chamber. A quantity of an oil feedstock is within the oil feedstock chamber, the oil feedstock comprising at least one carbon atom and a heteroatom and/or one or more heavy metals, the oil feedstock further comprising naphthenic acid. When the alkali metal ion enters the oil feedstock chamber, the alkali metal reacts with the heteroatom, the heavy metals and/or the naphthenic acid, wherein the reaction with the alkali metal forms inorganic products.

  11. Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl-Protected Body-Centered Cubic Cluster [Au7 Ag8 (C≡C(t) Bu)12 ]().

    Science.gov (United States)

    Wang, Yu; Su, Haifeng; Ren, Liting; Malola, Sami; Lin, Shuichao; Teo, Boon K; Häkkinen, Hannu; Zheng, Nanfeng

    2016-11-21

    The synthesis, structure, substitution chemistry, and optical properties of the gold-centered cubic monocationic cluster [Au@Ag8 @Au6 (C≡C(t) Bu)12 ](+) are reported. The metal framework of this cluster can be described as a fragment of a body-centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [Mn Ag8-n Au7 (C≡C(t) Bu)12 ](+) clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [Cun Ag8 Au7-n (C≡C(t) Bu)12 ](+) clusters (n=1-6), with the Cu atom(s) presumably occupying the capping site(s). The parent cluster exhibited strong emission in the near-IR region (λmax =818 nm) with a quantum yield of 2 % upon excitation at λ=482 nm. Its photoluminescence was quenched upon substitution with a Na(+) ion. DFT calculations confirmed the superatom characteristics of the title compound and the sodium-substituted derivatives.

  12. Vibrations of alkali metal overlayers on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rusina, G G; Eremeev, S V; Borisova, S D [Institute of Strength Physics and Materials Science SB RAS, 634021, Tomsk (Russian Federation); Echenique, P M; Chulkov, E V [Donostia International Physics Center (DIPC), 20018 San Sebastian/Donostia, Basque Country (Spain); Benedek, G [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy)], E-mail: rusina@ispms.tsc.ru

    2008-06-04

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation.

  13. Vibrations of alkali metal overlayers on metal surfaces

    Science.gov (United States)

    Rusina, G. G.; Eremeev, S. V.; Echenique, P. M.; Benedek, G.; Borisova, S. D.; Chulkov, E. V.

    2008-06-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation.

  14. Alkali metal cation-hexacyclen complexes: effects of alkali metal cation size on the structure and binding energy.

    Science.gov (United States)

    Austin, C A; Rodgers, M T

    2014-07-24

    Threshold collision-induced dissociation (CID) of alkali metal cation-hexacyclen (ha18C6) complexes, M(+)(ha18C6), with xenon is studied using guided ion beam tandem mass spectrometry techniques. The alkali metal cations examined here include: Na(+), K(+), Rb(+), and Cs(+). In all cases, M(+) is the only product observed, corresponding to endothermic loss of the intact ha18C6 ligand. The cross-section thresholds are analyzed to extract zero and 298 K M(+)-ha18C6 bond dissociation energies (BDEs) after properly accounting for the effects of multiple M(+)(ha18C6)-Xe collisions, the kinetic and internal energy distributions of the M(+)(ha18C6) and Xe reactants, and the lifetimes for dissociation of the activated M(+)(ha18C6) complexes. Ab initio and density functional theory calculations are used to determine the structures of ha18C6 and the M(+)(ha18C6) complexes, provide molecular constants necessary for the thermodynamic analysis of the energy-resolved CID data, and theoretical estimates for the M(+)-ha18C6 BDEs. Calculations using a polarizable continuum model are also performed to examine solvent effects on the binding. In the absence of solvent, the M(+)-ha18C6 BDEs decrease as the size of the alkali metal cation increases, consistent with the noncovalent nature of the binding in these complexes. However, in the presence of solvent, the ha18C6 ligand exhibits selectivity for K(+) over the other alkali metal cations. The M(+)(ha18C6) structures and BDEs are compared to those previously reported for the analogous M(+)(18-crown-6) and M(+)(cyclen) complexes to examine the effects of the nature of the donor atom (N versus O) and the number donor atoms (six vs four) on the nature and strength of binding.

  15. Alkali-metal-supported bismuth polyhedra-principles and theoretical studies.

    Science.gov (United States)

    Monakhov, Kirill Yu; Linti, Gerald; Wolters, Lando P; Bickelhaupt, F Matthias

    2011-06-20

    We have quantum chemically investigated the structure, stability, and bonding mechanism in highly aggregated alkali-metal salts of bismuthanediide anions [RBi](2-) using relativistic density functional theory (DFT, at ZORA-BP86/TZ2P) in combination with a quantitative energy decomposition analysis (EDA). Our model systems are alkali-metal-supported bismuth polyhedra [(RBi)(n)M(2n-4)](4-) with unique interpenetrating shells of a bismuth polyhedron and an alkali-metal superpolyhedron. Furthermore, we have analyzed the trianionic inclusion complexes [M'@{(RBi)(n)M(2n-4)}](3-) involving an additional endohedral alkali-metal ion M'. The main objective is to assist the further development of synthetic approaches toward this class of compounds. Our analyses led to electron-counting rules relating, for example, the number of bonding orbitals (N(bond)) of the cage molecules [(RBi)(n)M(2n+Q)](Q) to the number of bismuth atoms (n(Bi)), alkali-metal atoms (n(M)), and net charge Q as N(bond) = n(Bi) + n(M) - Q (R = one-electron donor ligand; M = alkali metal; n = 4-12; Q = -4, -6, -8). Finally, on the basis of our findings, we predict the next members in the 5-fold symmetrical row of alkali-metallobismaspheres with a macroicosahedral arrangement.

  16. Is electronegativity a useful descriptor for the pseudo-alkali metal NH4?

    Science.gov (United States)

    Whiteside, Alexander; Xantheas, Sotiris S; Gutowski, Maciej

    2011-11-18

    Molecular ions in the form of "pseudo-atoms" are common structural motifs in chemistry, with properties that are transferrable between different compounds. We have determined one such property--the electronegativity--for the "pseudo-alkali metal" ammonium (NH(4)), and evaluated its reliability as a descriptor versus the electronegativities of the alkali metals. The computed properties of ammonium's binary complexes with astatine and of selected borohydrides confirm the similarity of NH(4) to the alkali metal atoms, although the electronegativity of NH(4) is relatively large in comparison to its cationic radius. We have paid particular attention to the molecular properties of ammonium (angular anisotropy, geometric relaxation and reactivity), which can cause deviations from the behaviour expected of a conceptual "true alkali metal" with this electronegativity. These deviations allow for the discrimination of effects associated with the molecular nature of NH(4).

  17. 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.

  18. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both simi

  19. A multinuclear solid-state NMR study of alkali metal ions in tetraphenylborate salts, M[BPh4] (M = Na, K, Rb and Cs): what is the NMR signature of cation-pi interactions?

    Science.gov (United States)

    Wu, Gang; Terskikh, Victor

    2008-10-16

    We report a multinuclear solid-state ( (23)Na, (39)K, (87)Rb, (133)Cs) NMR study of tetraphenylborate salts, M[BPh 4] (M = Na, K, Rb, Cs). These compounds are isostructural in the solid state with the alkali metal ion surrounded by four phenyl groups resulting in strong cation-pi interactions. From analyses of solid-state NMR spectra obtained under stationary and magic-angle spinning (MAS) conditions at 11.75 and 21.15 T, we have obtained the quadrupole coupling constants, C Q, and the chemical shift tensor parameters for the alkali metal ions in these compounds. We found that the observed quadrupole coupling constant for M (+) in M[BPh 4] is determined by a combination of nuclear quadrupole moment, Sternheimer antishielding factor, and unit cell dimensions. On the basis of a comparison between computed paramagnetic and diamagnetic contributions to the total chemical shielding values for commonly found cation-ligand interactions, we conclude that cation-pi interactions give rise to significantly lower paramagnetic shielding contributions than other cation-ligand interactions. As a result, highly negative chemical shifts are expected to be the NMR signature for cations interacting exclusively with pi systems.

  20. Rydberg Matter clusters of alkali metal atoms: the link between meteoritic matter, polar mesosphere summer echoes (PMSE), sporadic sodium layers, polar mesospheric clouds (PMCs, NLCs), and ion chemistry

    CERN Document Server

    Olofson, Frans; Holmlid, Leif

    2010-01-01

    A material exists which links together the influx of meteoritic matter from interplanetary space, the polar mesosphere summer echoes (PMSE), the sporadic sodium layers, the polar mesospheric clouds (PMCs, NLCs), and the observed ion chemistry in the mesosphere. The evidence in these research fields is here analyzed and found to agree well with the properties of Rydberg Matter (RM). This material has been studied with numerous methods in the laboratory. Alkali atoms, mainly Na, reach the mesosphere in the form of interplanetary (meteoritic, cometary) dust. The planar RM clusters NaN usually contain N = 19, 37 or 61 atoms, and have the density of air at 90 km altitude where they float. The diameters of the clusters are 10-100 nm from laboratory high precision radio frequency spectroscopic studies. Such experiments show that RM clusters interact strongly with radar frequencies: this explains the radio frequency heating and reflection studies of PMSE layers. The clusters give the low temperature in the mesosphere...

  1. Superconductivity in alkali-metal-doped picene.

    Science.gov (United States)

    Mitsuhashi, Ryoji; Suzuki, Yuta; Yamanari, Yusuke; Mitamura, Hiroki; Kambe, Takashi; Ikeda, Naoshi; Okamoto, Hideki; Fujiwara, Akihiko; Yamaji, Minoru; Kawasaki, Naoko; Maniwa, Yutaka; Kubozono, Yoshihiro

    2010-03-04

    Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds, boron-doped diamond and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7 K and 18 K, depending on the metal content. The drop of magnetization in K(x)picene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite. The T(c) of 18 K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.

  2. Controlled in-situ dissolution of an alkali metal

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Jeffrey Donald; Dooley, Kirk John; Tolman, David Donald

    2012-09-11

    A method for the controllable dissolution of one or more alkali metals from a vessel containing a one or more alkali metals and/or one or more partially passivated alkali metals. The vessel preferably comprising a sodium, NaK or other alkali metal-cooled nuclear reactor that has been used. The alkali metal, preferably sodium, potassium or a combination thereof, in the vessel is exposed to a treatment liquid, preferably an acidic liquid, more preferably citric acid. Preferably, the treatment liquid is maintained in continuous motion relative to any surface of unreacted alkali metal with which the treatment liquid is in contact. The treatment liquid is preferably pumped into the vessel containing the one or more alkali metals and the resulting fluid is extracted and optionally further processed. Preferably, the resulting off-gases are processed by an off-gas treatment system and the resulting liquids are processed by a liquid disposal system. In one preferred embodiment, an inert gas is pumped into the vessel along with the treatment liquid.

  3. Estimating the hydration enthalpies of neutral alkali metal atoms.

    Science.gov (United States)

    Stace, A J

    2006-10-26

    Using existing data on the ionization energies of alkali metal atoms in small clusters of water, a thermodynamic cycle is proposed from which the hydration enthalpies of the neutral metal atoms can be estimated. Where comparisons are possible, the results are in reasonable agreement with those obtained using both experimental and ab initio methods. Application of the thermodynamic cycle to neutral alkali metal atoms solvated in ammonia yields solvation enthalpies that are significantly lower than those obtained for water.

  4. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    Science.gov (United States)

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  5. (abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    Science.gov (United States)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kisor, A.; Kikkert, S. K.

    1993-01-01

    The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 alkali metal vapor and alkali metal vapor/solid electrolyte/vapor cells have been used to characterize the reaction and transport processes. We have previously reported evidence of ionic, free molecular flow, and surface transport of sodium in several types of AMTEC electrodes.

  6. Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Tanghong; Chen, Wei; Cheng, Lei; Bayliss, Ryan D.; Lin, Feng; Plews, Michael R.; Nordlund, Dennis; Doeff, Marca M.; Persson, Kristin A.; Cabana, Jordi

    2017-02-07

    Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the nonoxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials AxK1–xFeF3 (A = Li, Na). By starting with KFeF3, approximately 75% of K+ ions were subsequently replaced by Li+ and Na+ through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe2+/3+ redox couple. A computational study by density functional theory showed agreement with the structural and electrochemical data obtained experimentally, which suggested the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.

  7. 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.)

  8. Lanthanide Single-Molecule Magnets Framed by Alkali Metals & Magnetic and Spectroscopic Studies of 3d Transition Metal Complexes

    DEFF Research Database (Denmark)

    Konstantatos, Andreas

    )imino)- methyl)benzene-1,2-diol]. Using this ligand, we were able to synthesize four different families of lanthanide complexes framed by alkali metals. Throughout the chapter we demonstrate how we can exploit the presence of the coordinated alkali metal ions in order to induce changes to the structure....... In Chapter 3 we present the results of our work with third row (3d) transition metal ions and their complexes. Specifically, in section 2.1 we report a series of complexes synthesized using a tripodal hexadentate Schiff-base ligand. The ligand demonstrates the ability to form mononuclear or trinuclear...... complexes of M3+ or M2+ metal ions (M: 3d transition metal) with the preference to either approximate octahedral or trigonal prismatic coordination geometry. A detailed magnetic characterization for most of the complexes is presented where a trinuclear Co2+ cluster stands out for its pronounced SMM...

  9. Two-phase alkali-metal experiments in reduced gravity

    Energy Technology Data Exchange (ETDEWEB)

    Antoniak, Z.I.

    1986-06-01

    Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity.

  10. Binding to Redox-Inactive Alkali and Alkaline Earth Metal Ions Strongly Deactivates the C-H Bonds of Tertiary Amides toward Hydrogen Atom Transfer to Reactive Oxygen Centered Radicals.

    Science.gov (United States)

    Salamone, Michela; Carboni, Giulia; Mangiacapra, Livia; Bietti, Massimo

    2015-09-18

    The effect of alkali and alkaline earth metal ions on the reactions of the cumyloxyl radical (CumO(•)) with N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) was studied by laser flash photolysis. In acetonitrile, a >2 order of magnitude decrease in the rate constant for hydrogen atom transfer (HAT) from the C-H bonds of these substrates (kH) was measured after addition of Li(+). This behavior was explained in terms of a strong interaction between Li(+) and the oxygen atom of both DMF and DMA that increases the extent of positive charge on the amide, leading to C-H bond deactivation toward HAT to the electrophilic radical CumO(•). Similar effects were observed after addition of Ca(2+), which was shown to strongly bind up to four equivalents of the amide substrates. With Mg(2+), weak C-H deactivation was observed for the first two substrate equivalents followed by stronger deactivation for two additional equivalents. No C-H deactivation was observed in DMSO after addition of Li(+) and Mg(2+). These results point toward the important role played by metal ion Lewis acidity and solvent Lewis basicity, indicating that C-H deactivation can be modulated by varying the nature of the metal cation and solvent and allowing for careful control over the HAT reactivity of amide substrates.

  11. Hydrogen storage over alkali metal hydride and alkali metal hydroxide composites

    Institute of Scientific and Technical Information of China (English)

    Pei Yu; Yong Shen Chua; Hujun Cao; Zhitao Xiong; Guotao Wu; Ping Chen

    2014-01-01

    Alkali metal hydroxide and hydride composite systems contain both protic (H bonded with O) and hydridic hydrogen. The interaction of these two types of hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of alkali metals, i.e.,-23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150◦C; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2 , and the corresponding entropy was ca. 101.23 J/(molH2 ·K), so the temperature for releasing 1.0 bar H2 was as high as 518◦C, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be 57.87 kJ/mol, showing good kinetic properties.

  12. Upgrading of petroleum oil feedstocks using alkali metals and hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard

    2014-09-09

    A method of upgrading an oil feedstock by removing heteroatoms and/or one or more heavy metals from the oil feedstock composition. This method reacts the oil feedstock with an alkali metal and an upgradant hydrocarbon. The alkali metal reacts with a portion of the heteroatoms and/or one or more heavy metals to form an inorganic phase separable from the organic oil feedstock material. The upgradant hydrocarbon bonds to the oil feedstock material and increases the number of carbon atoms in the product. This increase in the number of carbon atoms of the product increases the energy value of the resulting oil feedstock.

  13. Hydride encapsulation by molecular alkali-metal clusters.

    Science.gov (United States)

    Haywood, Joanna; Wheatley, Andrew E H

    2008-07-14

    The sequential treatment of group 12 and 13 Lewis acids with alkali-metal organometallics is well established to yield so-called ''ate' complexes, whereby the Lewis-acid metal undergoes nucleophilic attack to give an anion, at least one group 1 metal acting to counter this charge. However, an alternative, less well recognised, reaction pathway involves the Lewis acid abstracting hydride from the organolithium reagent via a beta-elimination mechanism. It has recently been shown that in the presence of N,N'-bidentate ligands this chemistry can be harnessed to yield a new type of molecular main-group metal cluster in which the abstracted LiH is effectively trapped, with the hydride ion occupying an interstitial site in the cluster core. Discussion focuses on the development of this field, detailing advances in our understanding of the roles of Lewis acid, organolithium, and amine substrates in the syntheses of these compounds. Structure-types are discussed, as are efforts to manipulate cluster geometry and composition as well as hydride-coordination. Embryonic mechanistic studies are reported, as well as attempts to generate hydride-encapsulation clusters under catalytic control.

  14. Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ogihara, Wataru; Yoshizawa, Masahiro; Ohno Hiroyuki [Tokyo University of Agriculture and Technology (Japan). Dept. of Biotechnology; Sun, Jiazeng; Forsyth, M. [Monash University, Clayton (Australia). School of Materials Engineering; MacFarlane, D.R. [Monash University, Clayton (Australia). School of Chemistry

    2004-04-30

    We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10{sup -4} to 10{sup -3} S cm{sup -1} at room temperature. Gelation was found to cause little change in the {sup 7}Li diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids. (author)

  15. Hydrogen Release Studies of Alkali Metal Amidoboranes

    Energy Technology Data Exchange (ETDEWEB)

    Luedtke, Avery T.; Autrey, Thomas

    2010-04-19

    A series of metal amido boranes LiNH2BH3 (LAB), NaNH2BH3 (SAB), LiNH(Me)BH3 (LMAB), NaNH(Me)BH3 (SMAB), KNH(Me)BH3 (PMAB), and KNH(tBu)BH3 (PBAB) were synthesized, by solution phase methods, and the thermal release of H2 in the solid state was studied. Based on the observed trends in reaction rates of H > Me > tBu and the kinetic isotope effect, the mechanism of hydrogen release from MAB compounds was found to proceed through a bimolecular mechanism involving the intermediacy of a MH (M = Li, Na, or K). The mechanism of hydrogen release from metal amidoboranes, a metal ion assisted hydride transfer, is very different than the mechanism of hydrogen release from the parent compound ammonia borane (AB). The non-volatile products formed from MAB’s are significantly different than the products formed after hydrogen release from AB. The boron containing resulting from the release of one equivalent of hydrogen from the metal amidoboranes were characterized by MAS 11B NMR spectroscopy and found to contain both BH3 and sp2 hybridized BH groups, consistent with a general structural feature MN(R)=BHN(R)MBH3. This work was funded by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy as part of the Chemical Hydrogen Storage CoE at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the U.S. DOE by Battelle. MAS NMR studies were performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at PNNL.

  16. IRMPD action spectroscopy of alkali metal cation-cytosine complexes: effects of alkali metal cation size on gas phase conformation.

    Science.gov (United States)

    Yang, Bo; Wu, R R; Polfer, N C; Berden, G; Oomens, J; Rodgers, M T

    2013-10-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both similar and distinctive spectral features over the range of ~1000-1900 cm(-1). The IRMPD spectra of the Li(+)(cytosine), Na(+)(cytosine), and K(+)(cytosine) complexes are relatively simple but exhibit changes in the shape and shifts in the positions of several bands that correlate with the size of the alkali metal cation. The IRMPD spectra of the Rb(+)(cytosine) and Cs(+)(cytosine) complexes are much richer as distinctive new IR bands are observed, and the positions of several bands continue to shift in relation to the size of the metal cation. The measured IRMPD spectra are compared to linear IR spectra of stable low-energy tautomeric conformations calculated at the B3LYP/def2-TZVPPD level of theory to identify the conformations accessed in the experiments. These comparisons suggest that the evolution in the features in the IRMPD action spectra with the size of the metal cation, and the appearance of new bands for the larger metal cations, are the result of the variations in the intensities at which these complexes can be generated and the strength of the alkali metal cation-cytosine binding interaction, not the presence of multiple tautomeric conformations. Only a single tautomeric conformation is accessed for all five alkali metal cation-cytosine complexes, where the alkali metal cation binds to the O2 and N3 atoms of the canonical amino-oxo tautomer of cytosine, M(+)(C1).

  17. Neuropsychiatric manifestations of alkali metal deficiency and excess

    Energy Technology Data Exchange (ETDEWEB)

    Yung, C.Y.

    1984-01-01

    The alkali metals from the Group IA of the periodic table (lithium, sodium, potassium, rubidium, cesium and francium) are reviewed. The neuropsychiatric aspects of alkali metal deficiencies and excesses (intoxications) are described. Emphasis was placed on lithium due to its clinical uses. The signs and symptoms of these conditions are characterized by features of an organic brain syndrome with delirium and encephalopathy prevailing. There are no clinically distinctive features that could be reliably used for diagnoses. Sodium and potassium are two essential alkali metals in man. Lithium is used as therapeutic agent in bipolar affective disorders. Rubidium has been investigated for its antidepressant effect in a group of psychiatric disorders. Cesium is under laboratory investigation for its role in carcinogenesis and in depressive illness. Very little is known of francium due to its great instability for experimental study.

  18. Electrochemistry of ytterbium (III) in molten alkali metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Smolenski, V.; Novoselova, A. [Institute of High-Temperature Electrochemistry, Ural Division, Russian Academy of Science, Ekaterinburg, 620219 (Russian Federation); Osipenko, A. [Research Institute of Atomic Reactors, Dimitrovgrad-10, Ulyanovsk Region, 433010 (Russian Federation); Caravaca, C. [High Level Waste Unit, Nuclear Fission Division, CIEMAT, Madrid, 28040 (Spain); Cordoba, G. de [High Level Waste Unit, Nuclear Fission Division, CIEMAT, Madrid, 28040 (Spain)], E-mail: g.cordoba@ciemat.es

    2008-12-30

    This work presents the electrochemical study of Yb(III) ions in molten alkali metal chlorides in the temperature range 723-1073 K. Transient electrochemical techniques such as linear sweep, cyclic and square wave voltammetry, and potentiometry at zero current have been used to investigate the reduction mechanism, transport parameters and thermodynamic properties of the reaction YbCl{sub 2} + 1/2Cl{sub 2} = YbCl{sub 3} The results obtained show that the reduction reaction Yb(III) + e{sup -} {r_reversible} Yb(II) is reversible being controlled by the rate of the mass transfer. The diffusion coefficient of [YbCl{sub 6}]{sup 3-} complex ions has been determined at different temperatures in the fused eutectic LiCl-KCl, the equimolar NaCl-KCl and the CsCl media. The apparent standard potential of the soluble-soluble redox system Yb(III)/Yb(II) has been obtained by cyclic voltammetry. The influence of the nature of the solvent on the electrochemical and thermodynamic properties of ytterbium compounds is discussed.

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

    Science.gov (United States)

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    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.

  20. On the origin of alkali metals in Europa exosphere

    Science.gov (United States)

    Ozgurel, Ozge; Pauzat, Françoise; Ellinger, Yves; Markovits, Alexis; Mousis, Olivier; LCT, LAM

    2016-10-01

    At a time when Europa is considered as a plausible habitat for the development of an early form of life, of particular concern is the origin of neutral sodium and potassium atoms already detected in its exosphere (together with magnesium though in smaller abundance), since these atoms are known to be crucial for building the necessary bricks of prebiotic species. However their origin and history are still poorly understood. The most likely sources could be exogenous and result from the contamination produced by Io's intense volcanism and/or by meteoritic bombardment. These sources could also be endogenous if these volatile elements originate directly from Europa's icy mantle. Here we explore the possibility that neutral sodium and potassium atoms were delivered to the satellite's surface via the upwelling of ices formed in contact with the hidden ocean. These metallic elements would have been transferred as ions to the ocean at early epochs after Europa's formation, by direct contact of water with the rocky core. During Europa's subsequent cooling, the icy layers formed at the top of the ocean would have kept trapped the sodium and potassium, allowing their future progression to the surface and final identification in the exosphere of the satellite. To support this scenario, we have used chemistry numerical models based on first principle periodic density functional theory (DFT). These models are shown to be well adapted to the description of compact ice and are capable to describe the trapping and neutralization of the initial ions in the ice matrix. The process is found relevant for all the elements considered, alkali metals like Na and K, as well as for Mg and probably for Ca, their respective abundances depending essentially of their solubility and chemical capabilities to blend with water ices.

  1. 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.

  2. Tuning the work function of ultrathin oxide films on metals by adsorption of alkali atoms.

    Science.gov (United States)

    Martinez, Umberto; Giordano, Livia; Pacchioni, Gianfranco

    2008-04-28

    We report a theoretical investigation of the adsorption of alkali metal atoms deposited on ultrathin oxide films. The properties of Li, Na, and K atoms adsorbed on SiO(2)/Mo(112) and of K on MgO / Ag(100) and TiO(2)/Pt(111) have been analyzed with particular attention to the induced changes in the work function of the system, Phi. On the nonreducible SiO(2) and MgO oxide films there is a net transfer of the outer ns electron of the alkali atom to the metal substrate conduction band; the resulting surface dipole substantially lowers Phi. The change in Phi depends (a) on the adsorption site (above the oxide film or at the interface) and (b) on the alkali metal coverage. Deposition of K on reducible TiO(2) oxide films results in adsorbed K(+) ions and in the formation of Ti(3+) ions. No charge transfer to the metal substrate is observed but also in this case the surface dipole resulting from the K-TiO(2) charge transfer has the effect to considerably reduce the work function of the system.

  3. Interactions and low energy collisions between an alkali ion and an alkali atom of different nucleus

    CERN Document Server

    Rakshit, Arpita; Berriche, Hamid; Deb, Bimalendu

    2015-01-01

    We study theoretically interaction potentials and low energy collisions between different alkali atoms and alkali ions. Specifically, we consider systems like X + Y$^{+}$, where X(Y$^{+})$ is either Li(Cs$^+$) or Cs((Li$^+$), Na(Cs$^+$) or Cs(Na$^+$) and Li(Rb$^+$) or Rb(Li$^+$). We calculate the molecular potentials of the ground and first two excited states of these three systems using pseudopotential method and compare our results with those obtained by others. We calculate ground-state scattering wave functions and cross sections of these systems for a wide range of energies. We find that, in order to get convergent results for the total scattering cross sections for energies of the order $1$ K, one needs to take into account at least 60 partial waves. In the low energy limit ($< 1 \\mu$K), elastic scattering cross sections exhibit Wigner law threshold behavior while in the high energy limit the cross sections go as $E^{-1/3}$. We discuss qualitatively the possibilities of forming cold molecular ion by ...

  4. A contribution to the surface characterization of alkali metal sulfates

    Energy Technology Data Exchange (ETDEWEB)

    Fantauzzi, Marzia; Rigoldi, Americo; Elsener, Bernhard; Atzei, Davide; Rossi, Antonella, E-mail: rossi@unica.it

    2014-03-01

    Highlights: • Full electronic characterization of alkali metals sulfates by X-ray photoelectron spectroscopy and X-ray induced Auger electron spectroscopy. • Curve-fitting of SKLL signals makes possible to clarify the role of the cation in the series of alkali metal sulfates. • Differences in the binding energies and Auger parameter are discussed in terms of the electronic properties and the polarizability of the cation. • The line intensities are analyzed and a thorough quantitative analysis is presented. - Abstract: The analytical characterization of surfaces of sulfur-bearing samples that present sulfides, polysulfides and/or elemental sulfur as reaction products can be difficult by simply relying on the binding energy of the S2p X-ray photoelectron signals, due to the small chemical shifts. In such cases the Auger parameter concept can be used to distinguish among different chemical states, but this requires a model to curve fit complex Auger SKLL signals in order to resolve the contributions arising from sulfur in different chemical states on the surface. With this scope a detailed X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) surface analytical study of the group IA sulfates is presented in this paper. Sulfates were chosen as model compounds for curve fitting the X-ray induced SKLL spectra since in these compounds sulfur is present in a unique chemical state. For the first time the multicomponent SKLL spectra are fitted with model functions consisting of an intense {sup 1}D and a low intensity {sup 1}S contribution with constant energy difference of 8 eV. It was found that the kinetic energy of the SK{sub 2,3}L{sub 2,3} ({sup 1}D) line increases from 2105.1 ± 0.1 to 2107.5 ± 0.2 eV whereas the corresponding S2p{sub 3/2} binding energy decreases from 169.5 ± 0.1 eV for Li{sub 2}SO{sub 4} to 167.8 ± 0.1 eV for Cs{sub 2}SO{sub 4}. Shifts to lower binding energy values are observed also for S2p, S2s and O1

  5. 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...

  6. 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.

  7. The different poisoning behaviors of various alkali metal containing compounds on SCR catalyst

    Science.gov (United States)

    Du, Xuesen; Yang, Guangpeng; Chen, Yanrong; Ran, Jingyu; Zhang, Li

    2017-01-01

    Alkali metals are poisonous to the metal oxide catalyst for NO removal. The chemical configuration of alkali containing substance and interacting temperature can affect the poisoning profile. A computational method based on Frontier Molecular Orbital analysis was proposed to determine the reacting behavior of various alkali-containing substances with SCR catalyst. The results reveal that the poisoning reactivities of various substances can be ranked as: E (MOH) > E (M2SO4) > E(MCl) > E(MNO3) > E(MHSO4). The experimental activity tests of the catalysts calcined at stepped temperatures show that NaOH can react with the catalyst below 200 °C. NaCl and NaNO3 start to react with the catalyst at a temperature between 300 and 400 °C. Unlike MOH, MCl and MNO3, which can produce volatile or decomposable species for the anions after reacting with the catalyst, M2SO4 and MHSO4 will leave both cations and anions on the catalyst surface. The sulfate ions left on the catalyst can generate active acid sites for NH3 adsorption. The experimental results also show that Na2SO4 and NaHSO4 will not lower the NO conversion. The after-reaction influences of various alkali metals were studied using theoretical and experimental methods. The theoretical results show that the acidity decreases with doping of alkali metal. Experiments show a consistent result that the NO conversion decreases as undoped >LiCl > NaCl > KCl.

  8. 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).

  9. Electron Paramagnetic Resonance and Optical Absorption Studies on Copper Ions in Mixed Alkali Cadmium Phosphate Glasses

    Institute of Scientific and Technical Information of China (English)

    G.Giridhar; M.Rangacharyulu; R.V.S.S.N.Ravikumar; P.Sambasiva Rao

    2009-01-01

    Electron paramagnetic resonance (EPR) and optical absorption studies were carried out at room temperature on copper doped mixed alkali cadmium phosphate (LiNaCdP) glasses to understand the nature and symmetry of dopant. Three samples with varying concentrations of alkali ions have been prepared. The spin Hamiltonian parameters obtained from room temperature EPR spectra are: g||=2.437, g⊥=2.096, A||=117×10-4 cm-1, A⊥=26×10-4 cm-1 for LiNaCdP1, g||=2.441, g⊥=2.088, A||=121×10-4 cm-1, A⊥=25×10-4 cm-1 for LiNaCdP2 and g||=2.433, g⊥=2.096, A||=125×10-4 cm-1, A⊥=32×10-4 cm-1 for LiNaCdP3. These EPR results indicate that the dopant Cu2+ ion enters the glass matrix into a tetragonally elongated octahedral site. The bonding parameters evaluated by correlating optical and EPR data suggest that bonding between the central metal ion and ligands is partially covalent. The mixed alkali effect in cadmium phosphate glasses was reported.

  10. Strong Turbulence in Alkali Halide Negative Ion Plasmas

    Science.gov (United States)

    Sheehan, Daniel

    1999-11-01

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

  11. Composition and thermodynamic properties of dense alkali metal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gabdullin, M.T. [NNLOT, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan); Ramazanov, T.S.; Dzhumagulova, K.N. [IETP, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan)

    2012-04-15

    In this work composition and thermodynamic properties of dense alkali metal plasmas (Li, Na) were investigated. Composition was derived by solving the Saha equations with corrections due to nonideality. The lowering of the ionization potentials was calculated on the basis of pseudopotentials by taking screening and quantum effects into account (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The unexpected properties of alkali metal iron selenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Dagotto, Elbio R [ORNL

    2013-01-01

    The iron-based superconductors that contain FeAs layers as the fundamental building block in the crystal structures have been rationalized in the past using ideas based on the Fermi surface nesting of hole and electron pockets when in the presence of weak Hubbard U interactions. This approach seemed appropriate considering the small values of the magnetic moments in the parent compounds and the clear evidence based on photoemission experiments of the required electron and hole pockets. However, recent results in the context of alkali metal iron selenides, with generic chemical composition AxFe2ySe2 (A alkali metal element), have challenged those previous ideas since at particular compositions y the low-temperature ground states are insulating and display antiferromagnetic order with large iron magnetic moments. Moreover, angle-resolved photoemission studies have revealed the absence of hole pockets at the Fermi level in these materials. The present status of this exciting area of research, with the potential to alter conceptually our understanding of the ironbased superconductors, is here reviewed, covering both experimental and theoretical investigations. Other recent related developments are also briefly reviewed, such as the study of selenide two-leg ladders and the discovery of superconductivity in a single layer of FeSe. The conceptual issues considered established for the alkali metal iron selenides, as well as several issues that still require further work, are discussed.

  13. Enhance luminescence by introducing alkali metal ions (R+ = Li+, Na+ and K+) in SrAl2O4:Eu3+ phosphor by solid-state reaction method

    Science.gov (United States)

    Prasad Sahu, Ishwar

    2016-05-01

    In the present article, the role of charge compensator ions (R+ = Li+, Na+ and K+) in europium-doped strontium aluminate (SrAl2O4:Eu3+) phosphors was synthesized by the high-temperature, solid-state reaction method. The crystal structures of sintered phosphors were in a monoclinic phase with space group P21. The trap parameters which are mainly activation energy (E), frequency factor (s) and order of the kinetics (b) were evaluated by using the peak shape method. The calculated trap depths are in the range from 0.76 to 0.84 eV. Photoluminescence measurements showed that the phosphor exhibited emission peak with good intensity at 595 nm, corresponding to 5D0-7F1 (514 nm) orange emission and weak 5D0-7F2 (614 nm) red emission. The excitation spectra monitored at 595 nm show a broad band from 220 to 320 nm ascribed to O-Eu charge-transfer state transition and the other peaks in the range of 350-500 nm originated from f-f transitions of Eu3+ ions. The strongest band at 394 nm can be assigned to 7F0-5L6 transition of Eu3+ ions due to the typical f-f transitions within Eu3+ of 4f6 configuration. The latter lies in near ultraviolet (350-500 nm) emission of UV LED. CIE color chromaticity diagram and thermoluminescence spectra confirm that the synthesized phosphors would emit an orange-red color. Incorporating R+ = Li+, Na+ and K+ as the compensator charge, the emission intensity of SrAl2O4:Eu3+ phosphor can be obviously enhanced and the emission intensity of SrAl2O4:Eu3+ doping Li+ is higher than that of Na+ or K+ ions.

  14. Alkali-metal ion coordination in uranyl(VI) poly-peroxide complexes in solution. Part 1: the Li⁺, Na⁺ and K⁺--peroxide-hydroxide systems.

    Science.gov (United States)

    Zanonato, Pier Luigi; Di Bernardo, Plinio; Vallet, Valerie; Szabó, Zoltán; Grenthe, Ingmar

    2015-01-28

    The alkali metal ions Li(+), Na(+) and K(+) have a profound influence on the stoichiometry of the complexes formed in uranyl(VI)-peroxide-hydroxide systems, presumably as a result of a templating effect, resulting in the formation of two complexes, M[(UO2)(O2)(OH)]2(-) where the uranyl units are linked by one peroxide bridge, μ-η(2)-η(2), with the second peroxide coordinated "end-on", η(2), to one of the uranyl groups, and M[(UO2)(O2)(OH)]4(3-), with a four-membered ring of uranyl ions linked by μ-η(2)-η(2) peroxide bridges. The stoichiometry and equilibrium constants for the reactions: M(+) + 2UO2(2+) + 2HO2(-) + 2H2O → M[(UO2)(O2)(OH)]2(-) + 4H(+) (1) and M(+) + 4UO2(2+) + 4HO2(-) + 4H2O → M[(UO2)(O2)(OH)]4(3-) + 8H(+) (2) have been measured at 25 °C in 0.10 M (tetramethyl ammonium/M(+))NO3 ionic media using reaction calorimetry. Both reactions are strongly enthalpy driven with large negative entropies of reaction; the observation that ΔH(2) ≈ 2ΔH(1) suggests that the enthalpy of reaction is approximately the same when peroxide is added in bridging and "end-on" positions. The thermodynamic driving force in the reactions is the formation of strong peroxide bridges and the role of M(+) cations is to provide a pathway with a low activation barrier between the reactants and in this way "guide" them to form peroxide bridged complexes; they play a similar role as in the synthesis of crown-ethers. Quantum chemical (QC) methods were used to determine the structure of the complexes, and to demonstrate how the size of the M(+)-ions affects their coordination geometry. There are several isomers of Na[(UO2)(O2)(OH)]2(-) and QC energy calculations show that the ones with a peroxide bridge are substantially more stable than the ones with hydroxide bridges. There are isomers with different coordination sites for Na(+) and the one with coordination to the peroxide bridge and two uranyl oxygen atoms is the most stable one.

  15. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    Science.gov (United States)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  16. Metal Ions in Unusual Valency States.

    Science.gov (United States)

    Sellers, Robin M.

    1981-01-01

    Discusses reactivity of metal ions with the primary products of water radiolysis, hyper-reduced metal ions, zero-valent metal ions, unstable divalent ions from the reduction of bivalent ions, hyper-oxidized metal ions, and metal complexes. (CS)

  17. Facilitated alkali ion transfer at the water 1,2-dichloroethane interphase Ab-initio calculations concerning alkaline metal cation - 1,10-phenanthroline complexes

    CERN Document Server

    Sánchez, C; Baruzzi, A M; Leiva, E P M

    1997-01-01

    A series of calculations on the energetics of complexation of alkaline metals with 1,10-phenanthroline are presented. It is an experimental fact that the ordering of the free energy of transfer across the water - 1,2-dichloroethane interphase is governed by the charge / size ratio of the diferent cations; the larger cations showing the lower free energy of transfer. This ordering of the free energies of transfer is reverted in the presence of 1,10-phenanthroline in the organic phase. We have devised a thermodynamic cycle for the transfer process and by means of ab-initio calculations have drawn the conclusion that in the presence of phen the free energy of transfer is governed by the stability of the PHEN/M $^{+}$complex, which explains the observed tendency from a theoretical point of view.

  18. Radioluminescence of synthetic quartz related to alkali ions

    Energy Technology Data Exchange (ETDEWEB)

    Martini, M., E-mail: m.martini@unimib.it [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); INFN-Sezione di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Fasoli, M. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Galli, A. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Istituto di Fotonica e Nanostrutture, IFN-CNR (Italy); Villa, I. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Guibert, P. [IRAMAT-CRP2A (Institut de recherche sur les Archeomateriaux), UMR no. 5060, CNRS-Universite Bordeaux III, F-33607 Pessac (France)

    2012-04-15

    The radioluminescence (RL) of synthetic quartzes (GEMMA Quartz and Crystal Company) has been measured at room temperature. Some samples were treated by electrodiffusion ('sweeping') in order to change the concentrations of alkali ions, mainly Li{sup +} and Na{sup +}, which in quartz are known to be linked to Al ions, substitutional for Si ions. The RL emission spectra show evidence of a role of alkali ions in affecting some specific emissions. All the spectra could be analysed as composed of four bands in the blue and UV region. Specifically, the well known blue emission at around 470 nm was seen to be composed by two bands at 430 nm (2.86 eV) and at 485 nm (2.53 eV). Effects of irradiation, during the RL measurements, were clearly seen only in the 'Li swept in' sample, namely an increase in the 485 nm band intensity and a decrease in the 430 nm band one. The previously reported UV emission was detected at 355 nm (3.44 eV) in all the samples, being the most intense band in the 'swept out' sample. A further UV emission was detected at 315 nm (3.94 eV), more intense in untreated samples. Possible assignments of the detected emission bands are discussed in relation to the defects of quartz, specifically focusing on the Al centres that are most affected by sweeping procedures. - Highlights: Black-Right-Pointing-Pointer Contribution to the understanding of relationships between defects in quartz and luminescence emissions. Black-Right-Pointing-Pointer Role of charge compensators at substitutional Al sites in the optical properties of quartz. Black-Right-Pointing-Pointer Evidence of the double nature of the 'blue emission' (around 470 nm).

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

    CERN Document Server

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

    2016-01-01

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

  20. Catalytically active Au-O(OH)x-species stabilized by alkali ions on zeolites and mesoporous oxides.

    Science.gov (United States)

    Yang, Ming; Li, Sha; Wang, Yuan; Herron, Jeffrey A; Xu, Ye; Allard, Lawrence F; Lee, Sungsik; Huang, Jun; Mavrikakis, Manos; Flytzani-Stephanopoulos, Maria

    2014-12-19

    We report that the addition of alkali ions (sodium or potassium) to gold on KLTL-zeolite and mesoporous MCM-41 silica stabilizes mononuclear gold in Au-O(OH)x-(Na or K) ensembles. This single-site gold species is active for the low-temperature (alkali ions and establishing an active site on various supports. The intrinsic activity of the single-site gold species is the same on irreducible supports as on reducible ceria, iron oxide, and titania supports, apparently all sharing a common, similarly structured gold active site. This finding paves the way for using earth-abundant supports to disperse and stabilize precious metal atoms with alkali additives for the WGS and potentially other fuel-processing reactions.

  1. 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.

  2. Periodic DFT approaches to crystalline alkali metal azides

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The energy bands, electronic structures andrelationship between structures and properties of the crys-talline alkali metal azides, LiN3, α-NaN3 and KN3, are investigated at the DFT-B3LYP level. The crystalline bulks arepredicted to be insulator, speculated from their band gaps ofca. 0.23-0.25 a.u. and from their level frontier bands. Theatomic overlaps and electron densities show that the metalsand the azides are combined by ionic bonds. The crystal lat-tice energies, being corrected for the basis set superpositionerrors, are -852.30, -771.45 and - 614.78 kJ @ mol-1 for LiN3,α-NaN3 and KN3 respectively. These values are similar tothose by Gray's approximate method. The frontier crystalorbital mainly consists of the atomic orbital of the terminalnitrogen of azides. The contribution of the metallic orbital tothe LUMO is very small. The electron transition from theHOMO to the LUMO is difficult to occur. Hence all the al-kali metal azides are expected to be insensitive explosives,according to the "principle of easiest electron transition".

  3. Integrated oil production and upgrading using molten alkali metal

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John Howard

    2016-10-04

    A method that combines the oil retorting process (or other process needed to obtain/extract heavy oil or bitumen) with the process for upgrading these materials using sodium or other alkali metals. Specifically, the shale gas or other gases that are obtained from the retorting/extraction process may be introduced into the upgrading reactor and used to upgrade the oil feedstock. Also, the solid materials obtained from the reactor may be used as a fuel source, thereby providing the heat necessary for the retorting/extraction process. Other forms of integration are also disclosed.

  4. Theoretical determination of the alkali-metal superoxide bond energies

    Science.gov (United States)

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

    1992-01-01

    The bond dissociation energies for the alkali-metal superoxides have been computed using extensive Gaussian basis sets and treating electron correlation at the modified coupled-pair functional level. Our computed D0 values are 61.4, 37.2, 40.6, and 38.4 kcal/mol for LiO2, NaO2, KO2, and RbO2, respectively. These values, which are expected to be lower bounds and accurate to 2 kcal/mol, agree well with some of the older flame data, but rule out several recent experimental measurements.

  5. Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect.

    Science.gov (United States)

    Samsonowicz, M; Regulska, E; Lewandowski, W

    2011-11-01

    The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions. The vibrational FT-IR (in KBr and ATR techniques) and (1)H and (13)C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg→Ba were compared with series of univalent metal Li→Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.

  6. Alkali-metalated forms of thiacalix[4]arenes.

    Science.gov (United States)

    Zeller, Jürgen; Radius, Udo

    2006-11-13

    The alkali metal salts [TCALi4] (1), [TCANa4] (2), and [TCALK4] (3) of fully deprotonated p-tert-butyltetrathiacalix[4]arene (H(4)TCA) are readily available from the reactions of thiacalix[4]arene and n-BuLi, NaH, or KH as deprotonating reagents. Crystals of the sodium salts 2 and the potassium salt 3 suitable for X-ray diffraction were obtained in the form of the pyridine solvates [(TCA)2Na8.8py] (2.8py) and [(TCA)2K(8).8py] (3.8py). These molecules are dimers in the solid state but are structurally not related. In addition, the reaction of H(4)TCA and lithium hydroxide afforded the structurally characterized complex [(TCA)Li5(OH).4THF] (4). The molecular structure of 4 as well as the structures of 2.8py and 3.8py reveal a close relationship to the corresponding alkali metal salts of the calix[4]arenes.

  7. Alkali metal-cationized serine clusters studied by sonic spray ionization tandem mass spectrometry.

    Science.gov (United States)

    Nanita, Sergio C; Sokol, Ewa; Cooks, R Graham

    2007-05-01

    Serine solutions containing salts of alkali metals yield magic number clusters of the type (Ser(4)+C)(+), (Ser(8)+C)(+), (Ser(12)+C)(+), and (Ser(17)+2C)(+2) (where C = Li(+), Na(+), K(+), Rb(+), or Cs(+)), in relative abundances which are strongly dependent on the cation size. Strong selectivity for homochirality is involved in the formation of serine tetramers cationized by K(+), Rb(+), and Cs(+). This is also the case for the octamers cationized by the smaller alkalis but there is a strong preference for heterochirality in the octamers cationized by the larger alkali cations. Tandem mass spectrometry shows that the octamers and dodecamers cationized by K(+), Rb(+), and Cs(+) dissociate mainly by the loss of Ser(4) units, suggesting that the neutral tetramers are the stable building blocks of the observed larger aggregates, (Ser(8)+C)(+) and (Ser(12)+C)(+). Remarkably, although the Ser(4) units are formed with a strong preference for homochirality, they aggregate further regardless of their handedness and, therefore, with a preference for the nominally racemic 4D:4L structure and an overall strong heterochiral preference. The octamers cationized by K(+), Rb(+), or Cs(+) therefore represent a new type of cluster ion that is homochiral in its internal subunits, which then assemble in a random fashion to form octamers. We tentatively interpret the homochirality of these tetramers as a consequence of assembly of the serine molecules around a central metal ion. The data provide additional evidence that the neutral serine octamer is homochiral and is readily cationized by smaller ions.

  8. Development of a new analysis method evaluating adsorption energies for the respective ion-exchanged sites on alkali-metal ion-exchanged ZSM-5 utilizing CO as a probe molecule: IR-spectroscopic and calorimetric studies combined with a DFT method.

    Science.gov (United States)

    Kumashiro, Ryotaro; Fujie, Kazuhiko; Kondo, Aki; Mori, Toshinori; Nagao, Mahiko; Kobayashi, Hisayoshi; Kuroda, Yasushige

    2009-07-07

    For alkali-metal ion-exchanged ZSM-5 zeolites (MZSM-5; M: Li, Na, K, Rb, Cs) the analysis of ion-exchangeable sites was performed by means of a combined method based on IR spectroscopic and calorimetric measurements using CO as the probe molecule. The heat of adsorption of CO was found to be correlated with an IR frequency of stretching vibration of C-O in the adsorbed species. It was revealed that there exists at least two types of sites capable of ion-exchanging; for the lithium ion-exchanged ZSM-5 (LiZSM-5) CO adsorption on each type of site is evaluated to give a set of IR bands and heats of adsorption, 2195 cm(-1) and 49 kJ mol(-1), 2185 cm(-1) and 39 kJ mol(-1) with the aid of the newly developed method utilizing the data obtained from a combined microcalorimetric and IR-spectroscopic study. Such types of data were also obtained for Na- and K-ion-exchanged ZSM-5 samples. Furthermore, a linear relationship between the differential heat of adsorption (q(diff)) evaluated and the shift of wavenumber of the C-O stretching vibration from that of a gaseous CO molecule (Deltanu) was established for the systems of MZSM-5-CO, and the bonding nature of the CO molecule with each site can be explained in terms of the electrostatic force. The model of each adsorption site was also examined by the quantum calculation method (density functional theory: DFT). The trends obtained from the experimental data may be substantially supported by the calculation method even adopting a model as simple as the ZSM-5-type zeolite: the composition of MAlSi(4)O(4)H(12).

  9. Binding and selectivity of phenazino-18-crown-6-ether with alkali, alkaline earth and toxic metal species: A DFT study

    Science.gov (United States)

    Islam, Nasarul; Chimni, Swapandeep Singh

    2017-02-01

    The interactions of phenazino-crown ether ligands with alkali, alkaline earth and selected toxic species were investigated using density functional theory modelling by employing B3PW91/6-311G ++ (d, p) level of theory. The complex stability was analysed in terms of binding energies, perturbation energies, position of highest molecular orbital and energy gap values. In general, the complexes formed by P18C6-1a ligand with metal cations were found to be more stable than those with P18C6-1b. Among alkali and alkaline earth metals complexes having highest stability was observed for the complex formed by P18C6-1a with Be2+. Computational calculations of P18C6 ligand with toxic metal ions reveals that the P18C6-Cr6+ metal complexes acquire envelop like geometry, leading to higher binding energy values. Comparing the binding energies of neutral and monocations of Ag and Hg, the former had higher value both in neutral as well as monocation state. Thus, the stability of metal complexes is determined not only by the ligand but also by the type of metal ion. In solvent systems the stability constants of metal complexes were found increasing with decreasing permittivity of the solvent. This reflects the inherited polar character of the protic solvents stabilises the cation, resulting in decrease of effective interaction of ligand with the metal ion.

  10. Path integral Monte Carlo study of 4He clusters doped with alkali and alkali-earth ions.

    Science.gov (United States)

    Galli, D E; Ceperley, D M; Reatto, L

    2011-06-30

    Path integral Monte Carlo calculations of (4)He nanodroplets doped with alkali (Na(+), K(+) and Cs(+)) and alkali-earth (Be(+) and Mg(+)) ions are presented. We study the system at T = 1 K and between 14 and 128 (4)He atoms. For all studied systems, we find that the ion is well localized at the center of the droplet with the formation of a "snowball" of well-defined shells of localized (4)He atoms forming solid-like order in at least the first surrounding shell. The number of surrounding helium shells (two or three) and the number of atoms per shell and the degree of localization of the helium atoms are sensitive to the type of ion. The number of (4)He atoms in the first shell varies from 12 for Na(+) to 18 for Mg(+) and depends weakly on the size of the droplet. The study of the density profile and of the angular correlations shows that the local solid-like order is more pronounced for the alkali ions with Na(+) giving a very stable icosahedral order extending up to three shells.

  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. 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.

  13. Improvement of a polarized alkali ion source by means of optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Koch, E.; Jaensch, H.; Kamke, W.; Broermann, W.; Fick, D.

    1982-01-01

    A source for polarized alkali ions can be improved considerably by optical pumping of the atom beam in combination with a modified weak field transition. M-level populations were investigated using laser induced fluorescence in a magnetic field.

  14. 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.

  15. An alternative picture of alkali-metal-mediated metallation: cleave and capture chemistry.

    Science.gov (United States)

    Mulvey, Robert E

    2013-05-21

    This perspective article takes an alternative look at alkali-metal-mediated chemistry (exchange of a relatively inert C-H bond for a more reactive C-metal bond by a multicomponent reagent usually containing an alkali metal and a less electropositive metal such as magnesium or zinc). It pictures that the cleavage of selected C-H bonds can be accompanied by the capturing of the generated anion by the multi (Lewis acid)-(Lewis base) character of the residue of the bimetallic base. In this way small atoms or molecules (hydrides, oxygen-based anions) as well as sensitive organic anions (of substituted aromatic compounds, ethers or alkenes) can be captured. Cleave and capture reactions which occur in special positions on the organic substrate are also included.

  16. Examination of Solubility Models for the Determination of Transition Metals within Liquid Alkali Metals

    Directory of Open Access Journals (Sweden)

    Jeremy Isler

    2016-06-01

    Full Text Available The experimental solubility of transition metals in liquid alkali metal was compared to the modeled solubility calculated using various equations for solubility. These equations were modeled using the enthalpy calculations of the semi-empirical Miedema model and various entropy calculations. The accuracy of the predicted solubility compared to the experimental data is more dependent on which liquid alkali metal is being examined rather than the transition metal solute examined. For liquid lithium the calculated solubility by the model was generally larger than experimental values, while for liquid cesium the modeling solubility was significantly smaller than the experimental values. For liquid sodium, potassium, and rubidium the experimental solubilities were within the range calculated by this study. Few data approached the predicted temperature dependence of solubility and instead most data exhibited a less pronounced temperature dependence.

  17. Assessment of alkali metal coolants for the ITER blanket

    Science.gov (United States)

    Natesan, K.; Reed, C. B.; Mattas, R. F.

    1994-06-01

    The blanket system is one of the most important components of a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The blanket comparison and selection study, conducted earlier, described the overall comparative performance of different blanket concepts, including liquid metal, molten salt, water, and helium. This paper will discuss the ITER requirements for a self-cooled blanket concept with liquid lithium and for indirectly cooled concepts that use other alkali metals such as NaK. The paper addresses the thermodynamics of interactions between the liquid metals (e.g., lithium and NaK) and structural materials (e.g., V-base alloys), together with associated corrosion/compatibility issues. Available experimental data are used to assess the long-term performance of the first wall in a liquid metal environment. Other key issues include development of electrical insulator coatings on the first-wall structural material to MHD pressure drop, and tritium permeation/inventory in self-cooled and indirectly cooled concepts. Acceptable types of coatings (based on their chemical compatibility and physical properties) are identified, and surface-modification avenues to achieve these coatings on the first wall are discussed. The assessment examines the extent of our knowledge on structural materials performance in liquid metals and identifies needed research and development in several of the areas in order to establish performance envelopes for the first wall in a liquid-metal environment.

  18. Calculation of Interaction Parameters from Immiscible Phase Diagram of Alkali Metal or Alkali Earth Metal-Halide System by Means of Subregular Solution Model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, the interaction parameters in the subregular solution model, λ1 and λ2, are regarded as a linear function of temperature, T. Therefore, the molar excess Gibbs energy of A-B binary system may be reexpressed as follows: The calculation of the model parameters, λ11, λ12, λ21 and λ22, was carried out numerically from the phase diagrams for 11 alkali metal-alkali halide or alkali earth metal-halide systems.In addition, artificial neural network trained by known data has been used to predict the values of these model parameters. The predicted results are in good agreement with the.calculated ones. The applicability of the subregular solution model to the alkali metal-alkali halide or alkali earth metal-halide systems were tested by comparing the available experimental composition along the boundary of miscibility gap with the calculated ones which were obtained by using genetic algorithm. The good agreement between the calculated and experimental results across the entire liquidus is valid evidence in support of the model.

  19. Researches of the electrotechnical laboratory. No. 973: Study on alkali metal thermoelectric converter

    Science.gov (United States)

    Tanaka, K.; Negishi, A.; Honda, T.; Fujii, T.; Masuda, T.; Nozaki, K.

    1995-03-01

    The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting Beta' '- alumina solid electrolyte (BASE) is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies (20 to 40 percent), high power densities (1 W/sq cm), 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.

  20. Thermochemical Ablation Therapy of VX2 Tumor Using a Permeable Oil-Packed Liquid Alkali Metal

    OpenAIRE

    2015-01-01

    Objective Alkali metal appears to be a promising tool in thermochemical ablation, but, it requires additional data on safety is required. The objective of this study was to explore the effectiveness of permeable oil-packed liquid alkali metal in the thermochemical ablation of tumors. Methods Permeable oil-packed sodium–potassium (NaK) was prepared using ultrasonic mixing of different ratios of metal to oil. The thermal effect of the mixture during ablation of muscle tissue ex vivo was evaluat...

  1. Alkali-crown ether complexes at metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Thontasen, Nicha; Deng, Zhitao; Rauschenbach, Stephan [Max Planck Institute for Solid State Research, Stuttgart (Germany); Levita, Giacomo [University of Trieste, Trieste (Italy); Malinowski, Nikola [Max Planck Institute for Solid State Research, Stuttgart (Germany); Bulgarian Academy of Sciences, Sofia (Bulgaria); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); EPFL, Lausanne (Switzerland)

    2010-07-01

    Crown ethers are polycyclic ethers which, in solution, selectively bind cations depending on the size of the ring cavity. The study of a single host-guest complex is highly desirable in order to reveal the characteristics of these specific interactions at the atomic scale. Such detailed investigation is possible at the surface where high resolution imaging tools like scanning tunneling microscopy (STM) can be applied. Here, electrospray ion beam deposition (ES-IBD) is employed for the deposition of Dibenzo-24-crown-8 (DB24C8)-H{sup +}, -Na{sup +} and -Cs{sup +} complexes on a solid surface in ultrahigh vacuum (UHV). Where other deposition techniques have not been successful, this deposition technique combines the advantages of solution based preparation of the complex ions with a highly clean and controlled deposition in UHV. Single molecular structures and the cation-binding of DB24C8 at the surface are studied in situ by STM and MALDI-MS (matrix assisted laser desorption ionization mass spectrometry). The internal structure of the complex, i.e. ring and cavity, is observable only when alkali cations are incorporated. The BD24C8-H{sup +} complex in contrast appears as a compact feature. This result is in good agreement with theoretical models based on density functional theory calculations.

  2. 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.

  3. 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.

  4. Study of Ion Specific Interactions of Alkali Cations with Dicarboxylate Dianions

    Energy Technology Data Exchange (ETDEWEB)

    Murdachaew, Garold; Valiev, Marat; Kathmann, Shawn M.; Wang, Xue B.

    2012-02-10

    Alkali metal cations often show pronounced ion specific interactions and selectivity with macromolecules in biological processes, colloids, and interfacial sciences, but a fundamental understanding about the underlying microscopic mechanism is still very limited. Here we report a direct probe of interactions between alkali metal cations (M{sup +}) and dicarboxylate dianions, O{sub 2}C(CH{sub 2})nCO{sub 2} (D{sub n}{sup 2-}) in the gas phase by combined photoelectron spectroscopy (PES) and ab initio electronic structure calculation on nine M{sup +}-D{sub n}{sup 2-} complexes (M = Li, Na, K; n = 2, 4, 6). PES spectra show that the electron binding energy (EBE) decreases from Li{sup +} to Na{sup +} to K{sup +} for complexes of M{sup +}-D{sub 2}{sup 2-}, whereas the order is Li{sup +} ion specificity and selectivity in solutions and biological systems.

  5. Zintl cluster chemistry in the alkali-metal-gallium systems

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Robert [Iowa State Univ., Ames, IA (United States)

    1998-03-27

    Previous research into the alkali-metal-gallium systems has revealed a large variety of networked gallium deltahedra. The clusters are analogues to borane clusters and follow the same electronic requirements of 2n+2 skeletal electrons for closo-deltahedra. This work has focused on compounds that do not follow the typical electron counting rules. The first isolated gallium cluster was found in Cs8Ga11. The geometry of the Ga117- unit is not deltahedral but can be described as a penta-capped trigonal prism. The reduction of the charge from a closo-Ga1113- to Ga117- is believed to be the driving force of the distortion. The compound is paramagnetic because of an extra electron but incorporation of a halide atom into the structure captures the unpaired electron and forms a diamagnetic compound. A second isolated cluster has been found in Na10Ga10Ni where the tetra-capped trigonal prismatic gallium is centered by nickel. Stabilization of the cluster occurs through Ni-Ga bonding. A simple two-dimensional network occurs in the binary K2Ga3 Octahedra are connected through four waist atoms to form a layered structure with the potassium atoms sitting between the layers. Na30.5Ga60-xAgx is nonstoichiometric and needs only a small amount of silver to form (x ~ 2-6). The structure is composed of three different clusters which are interconnected to form a three-dimensional structure. The RbGa3-xAux system is also nonstoichiometric with a three-dimensional structure composed of Ga8 dodecahedra and four-bonded gallium atoms. Unlike Na30.5Ga60-xAgx, the RbGa3 binary is also stable. The binary is formally a Zintl phase but the ternary is not. Some chemistry in the alkali-metal-indium system also has been explored. A new potassium-indium binary

  6. Formation of Metal-Adducted Analyte Ions by Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry.

    Science.gov (United States)

    Cheng, Sy-Chyi; Wang, Chin-Hsiung; Shiea, Jentaie

    2016-05-17

    A flame-induced atmospheric pressure chemical ionization (FAPCI) source, consisting of a miniflame, nebulizer, and heated tube, was developed to ionize analytes. The ionization was performed by reacting analytes with a charged species generated in a flame. A stainless steel needle deposited with saturated alkali chloride solution was introduced into the mini oxyacetylene flame to generate alkali ions, which were reacted with analytes (M) generated in a heated nebulizer. The alkali-adducted 18-crown-6 ether ions, including (M + Li)(+), (M + Na)(+), (M + K)(+), (M + Rb)(+), and (M + Cs)(+), were successfully detected on the FAPCI mass spectra when the corresponding alkali chloride solutions were separately introduced to the flame. When an alkali chloride mixture was introduced, all alkali-adducted analyte ions were simultaneously detected. Their intensity order was as follows: (M + Cs)(+) > (M + Rb)(+) > (M + K)(+) > (M + Na)(+) > (M + Li)(+), and this trend agreed with the lattice energies of alkali chlorides. Besides alkali ions, other transition metal ions such as Ni(+), Cu(+), and Ag(+) were generated in a flame for analyte ionization. Other than metal ions, the reactive species generated in the fossil fuel flame could also be used to ionize analytes, which formed protonated analyte ions (M + H)(+) in positive ion mode and deprotonated analyte ions (M - H)(-) in negative ion mode.

  7. Alkali Metal-incorporated Mesoporous Smectites:Crystallinity and Textural Properties

    Institute of Scientific and Technical Information of China (English)

    HE Yan-feng; Shinichiro Fujita; Nobuhiro Iwasa; Bhalchandra M. Bhanage; Masahiko Arai

    2003-01-01

    A series of mesoporous smectite-like materials incorporated with alkali metals such as Li, Na, K and Cs has been synthesized with the hydrothermal method. The crystalline and the pore structures of the materials synthesized significantly change with the introduction of alkali metals. The addition of Li gives highly ordered layer phases, while the incorporation of Cs yields much less crystalline structures. Although Na or K has little effect on the crystalline structure, they modify the pore structure.

  8. Calculated Pressure Induced BCC-FCC Phase Transitions in Alkali Metals

    OpenAIRE

    DAĞISTANLI, Hamdi; MUTLU, R. Haluk

    2008-01-01

    The partial occupation numbers and density of states (DOS), and the total DOS at the Fermi level are calculated as a function of reduced atomic volume for bcc and fcc alkali metals employing the linear-muffin-tin-orbital (LMTO) method. By means of the abrupt changes obtained in the partial and total DOS values at the Fermi level, good agreement with regard to experiment were found in predicting the bcc-fcc transition volumes of the alkali metals.

  9. Improved hydrogen desorption from lithium hydrazide by alkali metal hydride

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Liang, E-mail: liangzeng@hiroshima-u.ac.jp [Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Miyaoka, Hiroki [Institute for Sustainable Sciences and Development, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Ichikawa, Takayuki; Kojima, Yoshitsugu [Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)

    2013-12-15

    Highlights: •LiH can dramatically improve the hydrogen desorption properties of LiNHNH{sub 2}. •KH doping had positive effect in promoting the hydrogen desorption properties of LiNHNH{sub 2}–LiH mixture. •The reaction mechanism between LiNHNH{sub 2} and LiH was studied and discussed. -- Abstract: Lithium hydrazide (LiNHNH{sub 2}), which is a white solid with 8.0 mass% of theoretical hydrogen content, was synthesized from a reaction between anhydrous hydrazine and n-butyllithium in diethyl ether. The thermodynamic properties of this compound and its detailed decomposition pathways had been investigated in our previous work. However, a number of undesired gaseous products such as hydrazine (N{sub 2}H{sub 4}) and ammonia (NH{sub 3}) were generated during the thermal decomposition of LiNHNH{sub 2}. In this work, alkali metal hydride was used to suppress the impurities in the desorbed hydrogen and improved the hydrogen desorption properties. The reaction mechanism between LiNHNH{sub 2} and LiH was also studied and discussed in this paper.

  10. Effects of Heavy Metals and Saline-alkali on Growth, Physiology and Biochemistry of Orychophragmus violaceus

    Institute of Scientific and Technical Information of China (English)

    Xiaoai ZHANG; Zhihui WANG; Xinquan ZHANG; Mingyang Ll; Jing ZUO

    2012-01-01

    Abstract [Oh.jective] The aim was to study on effects of heavy metals and saline-al- kali on growth, physiology and biochemistry of Orychophragmus violaceus. [Method] Taken Orychophragmus violaceus as materials, growth, physiology and biochemistry were explored under stress of saline-alkali and heavy metals (light, moderate and se- vere saline-alkali, Pb, Pb + Cd, light saline-alkali + Pb, moderate saline-alkali + Pb, severe saline-alkali + Pb, light saline-alkali + Pb + Cd, moderate saline-alkali + Pb + Cd and severe saline-alkali + Pb + Cd) with control group set. [Result] Light stress of saline-alkali had little effect on membrane permeability, as follows: MDA contents in leaves and root systems declined by 25.6% and 9.0% compared with control group; Pb (500 mg/L) stress promoted synthetization of photosynthetic pigments, as follows: chlorophyll a and b and carotenoid increased by 0.86%, 0.69% and 6.25% than those of control group; combined stresses of Pb and Cd destroyed synthetization of photosynthetic pigments, among which carotenoid was more sensitive; under com- bined stresses of saline-alkali, Pb and Cd, POD and SOD activities, soluble saccha- rides and Pro content all increased and activities of POD and SOD in root system were both higher than those in leaves. [Conclusion] Orychophragmus violaceus is with resistance against light combined stresses of saline-alkali and Pb (500 mg/L).

  11. Alkali ion migration between stacked glass plates by corona discharge treatment

    Science.gov (United States)

    Kawaguchi, Keiga; Suzuki, Toshio; Ikeda, Hiroshi; Sakai, Daisuke; Funatsu, Shiro; Uraji, Keiichiro; Yamamoto, Kiyoshi; Harada, Kenji; Nishii, Junji

    2015-05-01

    Corona discharge reflects the spatial migration of alkali ions over a gap between two glass plates. This study examined stacked glass plates containing different alkali ions treated with the corona discharge plasma generated by applied voltage of 4.5 kV at 200 °C. Protons generated at the anode electrode penetrate into the potassium-ion-containing upper glass plate, which is located 5 mm below the anode electrode. Potassium ions intruded into the lower glass plate containing sodium ions placed on the cathode electrode, even over a 1 mm gap separating the plates. Finally, the sodium ion discharged on the cathode electrode. The hydrogen atmosphere was effective at inhibiting the potassium ion reaction with ambient gases during the spatial migration between the two glass plates.

  12. Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions

    Science.gov (United States)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  13. 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.

  14. Pi resonance of chemisorbed alkali atoms on noble metals.

    Science.gov (United States)

    Borisov, A G; Sametoglu, V; Winkelmann, A; Kubo, A; Pontius, N; Zhao, J; Silkin, V M; Gauyacq, J P; Chulkov, E V; Echenique, P M; Petek, H

    2008-12-31

    We have performed a joint experimental and theoretical study of the unoccupied electronic structure of alkali adsorbates on the (111) surfaces of Cu and Ag. Combining angle- and time-resolved two-photon photoemission spectroscopy with wave packet propagation calculations we show that, along with the well known sigma resonance oriented along the surface normal, there exist long-lived alkali-localized resonances oriented parallel to the surface (pi symmetry). These new resonances are stabilized by the projected band gap of the substrate and emerge primarily from the mixing of the p and d Rydberg orbitals of the free alkali atom modified by the interaction with the surface.

  15. Metal ion binding with dehydroannulenes - Plausible two-dimensional molecular sieves

    Indian Academy of Sciences (India)

    B Sateesh; Y Soujanya; G Narahari Sastry

    2007-09-01

    Theoretical investigations have been carried out at B3LYP/6-311++G∗∗ level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central cavity is controlled by the size of metal ion and dimension of dehydroannulene cavity.

  16. Determination of Alkali Metals, Ammonium Ion and Alkyl Amines by Non-Suppressed Ion Chromatography%非抑制型离子色谱法测定碱金属、铵离子和烷基胺

    Institute of Scientific and Technical Information of China (English)

    于泓; 李萍

    2001-01-01

    The determination of Li+,Na+,NH+4,K+,CH3NH2,CH3CH2NH2 and CH3CH2CH2NH2 by non-suppressed ion chromatography using sulfamic acid as mobile phase is described. A cation-exchange column was employed for separation with conductivity detection. The effect of the eluent concentration on retention value was studied. The retention value of ions decreased with increasing the eluent concentration.The suitable eluent concentration was 4.0 mmol/L. When 4.0 mmol/L sulfamic acid was used as mobile phase, the detection limits(mg/L) for Li+,Na+,NH+4,K+,CH3NH2,CH3CH2NH2 and CH3CH2CH2NH2 were 0.008,0.029,0.027,0.099,0.069,0.163 and 0.417 and the linear ranges of calibration curve(mg/L) were 0.008-20,0.029-20,0.027-20,0.099-30,0.069-30,0.163-40 and 0.417-40, respectively. The method has been applied to the determination of tap water samples. The recoveries of added standard were 94.0%-97.6%.%采用非抑制型离子色谱法、以氨磺酸作流动相分离测定了Li+、Na+、NH+4、K+、甲胺、乙胺和正丙胺等7种物质,研究了氨磺酸流动相浓度对溶质保留值的影响。结果发现,随着流动相浓度的增大,溶质保留值减小;适宜的流动相浓度为4.0 mmol/L。以4.0 mmol/L氨磺酸为流动相测得上述7种物质的检出限及工作曲线的线性回归方程。方法应用于自来水试样的分析,结果良好。

  17. Electrospray droplet exposure to organic vapors: metal ion removal from proteins and protein complexes.

    Science.gov (United States)

    DeMuth, J Corinne; McLuckey, Scott A

    2015-01-20

    The exposure of aqueous nanoelectrospray droplets to various organic vapors can dramatically reduce sodium adduction on protein ions in positive ion mass spectra. Volatile alcohols, such as methanol, ethanol, and isopropanol lead to a significant reduction in sodium ion adduction but are not as effective as acetonitrile, acetone, and ethyl acetate. Organic vapor exposure in the negative ion mode, on the other hand, has essentially no effect on alkali ion adduction. Evidence is presented to suggest that the mechanism by which organic vapor exposure reduces alkali ion adduction in the positive mode involves the depletion of alkali metal ions via ion evaporation of metal ions solvated with organic molecules. The early generation of metal/organic cluster ions during the droplet desolvation process results in fewer metal ions available to condense on the protein ions formed via the charged residue mechanism. These effects are demonstrated with holomyoglobin ions to illustrate that the metal ion reduction takes place without detectable protein denaturation, which might be revealed by heme loss or an increase in charge state distribution. No evidence is observed for denaturation with exposure to any of the organic vapors evaluated in this work.

  18. Hydrogen Adsorption by Alkali Metal Graphite Intercalation Compounds

    Science.gov (United States)

    Purewal, Justin

    Adsorption occurs whenever a solid surface is exposed to a gas or liquid, and is characterized by an increase in fluid density near the interface. Adsorbents have drawn attention in the current effort to engineer materials that store hydrogen at high densities within moderate temperature and pressure regimes. Carbon adsorbents are a logical choice as a storage material due to their low costs and large surface areas. Unfortunately, carbon adsorbents suffer from a low binding enthalpy for H2 (about 5 kJ mol-1), well below the 15 to 18 kJ mol-1) that is considered optimal for hydrogen storage systems. Binding interactions can be increased by the following methods: (1) adjusting the graphite interplanar separation with a pillared structure, and (2) introducing dopant species that interact with H2 molecules by strong electrostatic forces. Graphite intercalation compounds are a class of materials that contain both pillared structures and chemical dopants, making them an excellent model system for studying the fundamentals of hydrogen adsorption in nanostructured carbons. Pressure-composition-temperature diagrams of the MC24(H 2)x graphite intercalation compounds were measured for M = (K, Rb, Cs). Adsorption enthalpies were measured as a function of H2 concentration. Notably, CsC24 had an average adsorption enthalpy of 14.9 kJ mol-1), nearly three times larger than that of pristine graphite. The adsorption enthalpies were found to be positively correlated with the alkali metal size. Adsorption capacities were negatively correlated with the size of the alkali metal. The rate of adsorption is reduced at large H2 compositions, due to the effects of site-blocking and correlation on the H2 diffusion. The strong binding interaction and pronounced molecular-sieving behavior of KC24 is likely to obstruct the translational diffusion of adsorbed H2 molecules. In this work, the diffusion of H2 adsorbed in KC24 was studied by quasielastic neutron scattering measurements and molecular

  19. 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

    A low-temperature circulating fluidized bed system (LTCFB) gasifier allows for pyrolysis and gasification to occurat low temperatures, thereby improving the retention of alkali and other inorganic elements within the system and minimizingthe amount of ash species in the product gas. In addition......, 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...

  20. Multi-photon processes in alkali metal vapors

    Science.gov (United States)

    Gai, Baodong; Hu, Shu; Li, Hui; Shi, Zhe; Cai, Xianglong; Guo, Jingwei; Tan, Yannan; Liu, Wanfa; Jin, Yuqi; Sang, Fengting

    2015-02-01

    Achieving population inversion through multi-photon cascade pumping is almost always difficult, and most laser medium work under 1-photon excitation mechanism. But for alkali atoms such as cesium, relatively large absorption cross sections of several low, cascading energy levels enable them properties such as up conversion. Here we carried out research on two-photon excitation alkali fluorescence. Two photons of near infrared region are used to excite alkali atoms to n 2 D5/2, n 2 D3/2 or higher energy levels, then the blue fluorescence of (n+1) 2 P3/2,(n+1) 2 P1/2-->n 2 S1/2 are observed. Different pumping paths are tried and by the recorded spectra, transition routes of cesium are deducted and concluded. Finally the possibility of two-photon style DPALs (diode pumped alkali laser) are discussed, such alkali lasers can give output wavelengths in the shorter end of visual spectroscopy (400-460 nm) and are expected to get application in underwater communication and material laser processing.

  1. Alkali ion migration between stacked glass plates by corona discharge treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Keiga [Research Institute for Electronic Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Hokkaido 001-0020 (Japan); Suzuki, Toshio [Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama, Kanagawa 221-8755 (Japan); Ikeda, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Sakai, Daisuke [Department of Electrical and Electronic Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan); Funatsu, Shiro; Uraji, Keiichiro [Production Technology Center, Asahi Glass Co., Ltd., 1-1 Suehiro-cyo, Tsurumiku, Yokohama, Kanagawa 230-0045 (Japan); Yamamoto, Kiyoshi [Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa-ku, Yokohama, Kanagawa 221-8755 (Japan); Harada, Kenji [Department of Computer Science, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan); Nishii, Junji, E-mail: nishii@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Hokkaido 001-0020 (Japan)

    2015-05-30

    Highlights: • Two stacked glass plates with a 1 mm gap were treated by corona discharge. • Spatial migration of alkali ion over the gap was demonstrated. • Hydrogen gas was necessary for uniform migration. • Surface modification was done with this process without high temperature or vacuum. - Abstract: Corona discharge reflects the spatial migration of alkali ions over a gap between two glass plates. This study examined stacked glass plates containing different alkali ions treated with the corona discharge plasma generated by applied voltage of 4.5 kV at 200 °C. Protons generated at the anode electrode penetrate into the potassium-ion-containing upper glass plate, which is located 5 mm below the anode electrode. Potassium ions intruded into the lower glass plate containing sodium ions placed on the cathode electrode, even over a 1 mm gap separating the plates. Finally, the sodium ion discharged on the cathode electrode. The hydrogen atmosphere was effective at inhibiting the potassium ion reaction with ambient gases during the spatial migration between the two glass plates.

  2. 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

  3. Dissolution Process of Palladium in Hydrochloric Acid: A Route via Alkali Metal Palladates

    Science.gov (United States)

    Kasuya, Ryo; Miki, Takeshi; Morikawa, Hisashi; Tai, Yutaka

    2015-12-01

    To improve the safety of the Pd recovery processes that use toxic oxidizers, dissolution of Pd in hydrochloric acid with alkali metal palladates was investigated. Alkali metal palladates were prepared by calcining a mixture of Pd black and alkali metal (Li, Na, and K) carbonates in air. Almost the entire amount of Pd was converted into Li2PdO2 after calcination at 1073 K (800 °C) using Li2CO3. In contrast, PdO was obtained by calcination at 1073 K (800 °C) using Na and K carbonates. Our results indicated that Li2CO3 is the most active reagent among the examined alkali metal carbonates for the formation of palladates. In addition, dissolution of the resulting Li2PdO2 in HCl solutions was evaluated under various conditions. In particular, Li2PdO2 rapidly dissolved in diluted (0.1 M) HCl at ambient temperature. Solubility of Pd of Li2PdO2 was found to be 99 pct or larger after dissolution treatment at 353 K (80 °C) for 5 minutes; in contrast, PdO hardly dissolved in 0.1 M HCl. The dissolution mechanism of Li2PdO2 in HCl was also elucidated by analysis of crystal structures and particulate properties. Since our process is completely free from toxic oxidizers, the dissolution process via alkali metal palladates is much safer than currently employed methods.

  4. 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.

  5. Alkali ion sensor based on Prussian blue-covered interdigitated array electrodes

    NARCIS (Netherlands)

    Hartmann, M.; Grabner, E.W.; Bergveld, P.

    1991-01-01

    Thin films of ferric ferrocyanide (Prussian Blue) were electrochemically deposited on interdigitated array (IDA) electrodes yielding systems which can be considered as chemi-resistors in sensing alkali ion concentrations in an adjacent electrolyte. From the dependence of the steady-state current on

  6. Direct 1{sup +}{yields}N{sup +} conversion of stable alkali ions using an electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Mery, A.; Jardin, P.; Saint-Laurent, M. G.; Bajeat, O.; Delahaye, P.; Dubois, M.; Fraanberg-Delahaye, H.; Lecomte, P.; Leherissier, P.; Maunoury, L.; Pichard, A.; Pacquet, J. Y.; Thomas, J. C. [GANIL, Bd Henri Becquerel, BP 55027, 14076 CAEN Cedex 5 (France); Alcantara-Nunez, J. [Departamento de Fisica de Particulas, Universidad Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2010-02-15

    The production of radioactive ions using the Isotope Separation On-Line method gives rise, in most cases, to singly charged ions. In order to perform experiments with postaccelerated radioactive ion beams, these ions have to be multicharged. We describe here a new compact design for a charge breeder that will be coupled to the production target of SPIRAL1 at GANIL. We present recent results obtained offline with stable alkali ions (Na, K, Rb, and Cs) on the SIRa test bench. Particularly, 1{sup +} to N{sup +} conversion efficiencies and conversion times are presented. Several points have been identified for the improvements of the present performances.

  7. Hyperfine-frequency shifts of alkali-metal atoms during long-range collisions

    CERN Document Server

    McGuyer, B H

    2013-01-01

    Collisions with chemically inert atoms or molecules change the hyperfine coupling of an alkali-metal atom through the hyperfine-shift interaction. This interaction is responsible for the pressure shifts of the microwave resonances of alkali-metal atoms in buffer gases, is an important spin interaction in alkali-metal--noble-gas van der Waals molecules, and is anticipated to enable the magnetoassociation of ultracold molecules such as RbSr. An improved estimate is presented for the long-range asymptote of this interaction for Na, K, Rb, and Cs. To test the results, the change in hyperfine coupling due to a static electric field is estimated and reasonable agreement is found.

  8. A hetero-alkali-metal version of the utility amide LDA: lithium-potassium diisopropylamide.

    Science.gov (United States)

    Armstrong, David R; Kennedy, Alan R; Mulvey, Robert E; Robertson, Stuart D

    2013-03-14

    Designed to extend the synthetically important alkali-metal diisopropylamide [N(i)Pr(2); DA] class of compounds, the first example of a hetero-alkali-metallic complex of DA has been prepared as a partial TMEDA solvate. Revealed by an X-ray crystallographic study, its structure exists as a discrete lithium-rich trinuclear Li(2)KN(3) heterocycle, with TMEDA only solvating the largest of the alkali-metals, with the two-coordinate lithium atoms being close to linearity [161.9(2)°]. A variety of NMR spectroscopic studies, including variable temperature and DOSY NMR experiments, suggests that this new form of LDA maintains its integrity in non-polar hydrocarbon solution. This complex thus represents a rare example of a KDA molecule which is soluble in non-polar medium without the need for excessive amounts of solubilizing Lewis donor being added.

  9. 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(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (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(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)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)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=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.

  10. In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

    Directory of Open Access Journals (Sweden)

    Weijie Yan

    2017-03-01

    Full Text Available This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.

  11. Ternary Amides Containing Transition Metals for Hydrogen Storage: A Case Study with Alkali Metal Amidozincates.

    Science.gov (United States)

    Cao, Hujun; Richter, Theresia M M; Pistidda, Claudio; Chaudhary, Anna-Lisa; Santoru, Antonio; Gizer, Gökhan; Niewa, Rainer; Chen, Ping; Klassen, Thomas; Dornheim, Martin

    2015-11-01

    The alkali metal amidozincates Li4 [Zn(NH2)4](NH2)2 and K2[Zn(NH2)4] were, to the best of our knowledge, studied for the first time as hydrogen storage media. Compared with the LiNH2-2 LiH system, both Li4 [Zn(NH2)4](NH2)2-12 LiH and K2[Zn(NH2)4]-8 LiH systems showed improved rehydrogenation performance, especially K2[Zn(NH2)4]-8 LiH, which can be fully hydrogenated within 30 s at approximately 230 °C. The absorption properties are stable upon cycling. This work shows that ternary amides containing transition metals have great potential as hydrogen storage materials.

  12. Adsorption of alkali, alkaline-earth, and 3d transition metal atoms on silicene

    Science.gov (United States)

    Sahin, H.; Peeters, F. M.

    2013-02-01

    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, work function, and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na, and K, adsorb to hollow sites without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene, metalization of silicene takes place. Trends directly related to atomic size, adsorption height, work function, and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline-earth metals on silicene is entirely different from their adsorption on graphene. The adsorption of Be, Mg, and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo, and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic, and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal, and semiconducting behavior. For all metal adsorbates, the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

  13. 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...

  14. Influence of alkali metal cations on the thermal, mechanical and morphological properties of rectorite/chitosan bio-nanocomposite films.

    Science.gov (United States)

    Babul Reddy, A; Jayaramudu, J; Siva Mohan Reddy, G; Manjula, B; Sadiku, E R

    2015-05-20

    The main theme of this work is to study the influence of ion-exchangeable alkali metal cations, such as: Li(+), Na(+), K(+), and Cs(+) on the thermal, mechanical and morphological properties. In this regard, a set of rectorite/chitosan (REC-CS) bio-nanocomposite films (BNCFs) was prepared by facile reaction of chitosan with ion-exchanged REC clay. The microstructure and morphology of BNCFs were investigated with XRD, TEM, SEM and AFM. Thermal and tensile properties of BNCFs were also investigated. As revealed from TEM and XRD results, the BNCFs featured a mixed morphology. Some intercalated clay sheets, together with nano-sized clay tactoids were obtained in LiREC/CS, NaREC/CS and KREC/CS of the BNCFs. From fractured surface study, via SEM, it was observed that the dispersion of chitosan polymer attaches to (and covers) the clay platelets. FTIR confirmed strong hydrogen bonds between clay and chitosan polymer. In addition, the thermal stabilities significantly varied when alkali metal cations varied from Li(+) to Cs(+). The BNCFs featured high tensile strengths (up to 84 MPa) and tensile moduli (up to 45 GPa). After evaluating these properties of BNCFs, we came to conclusion that these bio-nano composites can be used for packaging applications.

  15. Surface phonons on Al(111) surface covered by alkali metals

    Science.gov (United States)

    Rusina, G. G.; Eremeev, S. V.; Borisova, S. D.; Sklyadneva, I. Yu.; Chulkov, E. V.

    2005-06-01

    We investigated the vibrational and structural properties of the Al(111)-(3×3)R30°-AM (AM=Na,K,Li) adsorbed systems using interaction potentials from the embedded-atom method. The surface relaxation, surface phonon dispersion, and polarization of vibrational modes for the alkali adatoms and the substrate atoms as well as the local density of states are discussed. Our calculated structural parameters are in close agreement with experimental and ab initio results. The obtained vibrational frequencies compare fairly well with the available experimental data.

  16. 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.

  17. 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.

  18. Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals

    NARCIS (Netherlands)

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

    2013-01-01

    The benchmark inclusion complexes formed by -cyclodextrin (CD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative CD-M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry,

  19. Absorption Spectroscopy of Rubidium in an Alkali Metal Dispenser Cell and Bleached Wave Analysis

    Science.gov (United States)

    2015-03-26

    resulted in a transmission too low below the detection limit of the photodiodes. When the current ceased, the spectrum almost immediately returned to a...absorption spectrum of a rubidium alkali metal dispenser (AMD) cell was obtained in order to determine the system’s suitability for use in a diode ...18 8. Cell Pressure vs. Required Current .............................................................................. 20 9. Time vs. Rubidium

  20. 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.

  1. Interaction of Cu(+) with cytosine and formation of i-motif-like C-M(+)-C complexes: alkali versus coinage metals.

    Science.gov (United States)

    Gao, Juehan; Berden, Giel; Rodgers, M T; Oomens, Jos

    2016-03-14

    The Watson-Crick structure of DNA is among the most well-known molecular structures of our time. However, alternative base-pairing motifs are also known to occur, often depending on base sequence, pH, or the presence of cations. Pairing of cytosine (C) bases induced by the sharing of a single proton (C-H(+)-C) may give rise to the so-called i-motif, which occurs primarily in expanded trinucleotide repeats and the telomeric region of DNA, particularly at low pH. At physiological pH, silver cations were recently found to stabilize C dimers in a C-Ag(+)-C structure analogous to the hemiprotonated C-dimer. Here we use infrared ion spectroscopy in combination with density functional theory calculations at the B3LYP/6-311G+(2df,2p) level to show that copper in the 1+ oxidation state induces an analogous formation of C-Cu(+)-C structures. In contrast to protons and these transition metal ions, alkali metal ions induce a different dimer structure, where each ligand coordinates the alkali metal ion in a bidentate fashion in which the N3 and O2 atoms of both cytosine ligands coordinate to the metal ion, sacrificing hydrogen-bonding interactions between the ligands for improved chelation of the metal cation.

  2. Energetics and bonding in aluminosilicate rings with alkali metal and alkaline-earth metal charge-compensating cations.

    Science.gov (United States)

    Gatti, Carlo; Ottonello, Giulio; Richet, Pascal

    2012-08-23

    The stabilizing effect of alkali and alkaline-earth metal ions on the oxygen donors of four- and six-membered faujausite-like rings has been calculated in terms of Kohn-Sham core-level (O1s) energy shifts with respect to these same complexes without cations. The results confirm and complement earlier investigations by Vayssilov and co-workers where Na(+) and K(+) were the only complexing cations. The oxygen donor centers in six-membered rings are stabilized by -3.6 ± 0.4, -3.9 ± 0.5, -7.3 ± 0.1, and -7.6 ± 0.2 eV by K(+), Na(+), Ca(2+), and Mg(2+) adions, respectively. The energy shifts are even greater for four-membered rings where the stabilization effects attain -3.7 ± 0.1, -4.1 ± 0.1, -8.1 ± 0.1, and -9.0 ± 0.1 eV, respectively. These effects are also observed on the low-lying σ-bonding and antibonding molecular orbitals (MOs) of the oxygen framework, but in a less systematic fashion. Clear relationships with the core-level shifts are found when the effects of alkali metal complexation are evaluated through electron localization/delocalization indices, which are defined in terms of the whole wave function and not just of the individual orbitals. Complexation with cations not only involves a small but significant electron sharing of the cation with the oxygen atoms in the ring but also enhances electron exchange among oxygen atoms while reducing that between the O atoms and the Si or Al atoms bonded to them. Such changes slightly increase from Na to K and from Mg to Ca, whereas they are significantly enhanced for alkaline-earth metals relative to alkali metals. With respect to Al-free complexes, Si/Al substitution and cation charge compensation generally enhance electron delocalization among the O atoms, except between those that are linked through an Al atom, and cause either an increased or a decreased Si-O ionicity (smaller/higher electron exchange) depending on the position of O in the chain relative to the Al atom(s). The generally increased

  3. 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.

  4. 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.

  5. Alkali metal cation doped Al-SBA-15 for carbon dioxide adsorption.

    Science.gov (United States)

    Zukal, Arnošt; Mayerová, Jana; Čejka, Jiří

    2010-01-01

    Mesoporous aluminosilicate adsorbents for carbon dioxide were prepared by the grafting of aluminium into SBA-15 silica using an aqueous solution of aluminium chlorohydrate. As the ion exchange sites are primarily associated with the presence of tetrahedrally coordinated aluminium, extra-framework aluminium on the SBA-15 surface was inserted into the silica matrix by a treatment with an aqueous solution of NH(4)OH. Synthesized mesoporous aluminosilicate preserving all the characteristic features of a mesoporous molecular sieve was finally modified by the alkali metal cation exchange. To examine carbon dioxide adsorption on prepared materials, adsorption isotherms in the temperature range from 0 °C to 60 °C were measured. Based on the known temperature dependence of adsorption isotherms, isosteric adsorption heats giving information on the surface energetics of CO(2) adsorption were calculated and discussed. The comparison of carbon dioxide isotherms obtained on aluminosilicate SBA-15, aluminosilicate SBA-15 containing cations Na(+) and K(+) and activated alumina F-200 reveals that the doping with sodium or potassium cations dramatically enhances adsorption in the region of equilibrium pressures lower than 10 kPa. Therefore, synthesized aluminosilicate adsorbents doped with Na(+) or K(+) cations are suitable for carbon dioxide separation from dilute gas mixtures.

  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. 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.

  8. Thermodynamic study of alkali metals release in pressurised fluidised-bed combustion and gasification of peat

    Energy Technology Data Exchange (ETDEWEB)

    Mojtahedi, W.; Backman, R.; Korhonen, M.

    1988-01-01

    A combined-cycle power generation system incorporating pressurised fluidised-bed combustion (PFBC) or gasification is considered a promising approach for electricity generation using solid fuels such as peat. In these systems, the high-pressure hot flue gas is expanded in a gas turbine. Peat contains sodium and potassium which are released in combustion and gasification. These are corrosive elements that can cause severe damage to the turbine blades if not suppressed. Multicomponent, multiphase equilibrium calculations were carried out for atmospheric and pressurised fluidised-bed operating conditions to determine the relative distribution of the two metals (Na and K) in the gas and condensed phases. Dependence of the alkali volatilisation on the operating temperature, pressure, the chlorine-content and the total alkali-content of the feedstock was studied. The results show that the alkali release in the vapour-phase could be much higher than acceptable to a gas turbine, particularly under gasification conditions. Hence the necessity to remove the volatilised alkali-metal compounds is more acute in gasification than in combustion. Both sodium and potassium are present as chlorides and to a lesser extent as hydroxides in the gas phase in both modes of operation (i.e. combustion and gasification). However, whereas under combustion conditions both metals seem to condense as sulphates (Na/sub 2/SO4 and K/sub 2/SO4), in gasification, chlorides and carbonates dominate in the condensed phase. The alkali-metals volatilisation shows strong dependence on the operating pressure of the system as well as on the chlorine-content of the feedstock. It decreases markedly with the former but increases sharply with the latter.

  9. Extraction of Alkali Ions Investigated by Conductometric and pH Measurements

    Directory of Open Access Journals (Sweden)

    L. Kalvoda

    2006-01-01

    Full Text Available Extraction of alkali ions from aqueous solutions of chlorides and hydroxides into a lipophilic liquid membrane composed of tetraethyl p-tert-butylcalix[4]arene tetraacetate (TBT solution in hexane was investigated by means of measurements of changes in the electrolytic conductivity and pH-value of the aqueous solution. Hydrolysis of the TBT ionophore resulting in the release of the ethyl groups was proposed as the main reaction process, leading to disturbance of the known preference of TBT for sodium ions

  10. 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.

  11. Effect of Some Metal Ion Dopants on Electrochemical Properties of Ni(OH)2 Film Electrode

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-bin; LIU Han-san; CAO Xue-jing; SUN Chia-chung

    2003-01-01

    The Ni(OH)2 film electrodes doped respectively with alkali-earth metal aluminum, lead, partial transition metal and some rare-earth metal(altogether 17 kinds of metals) ions were prepared by cathode electrodeposition. The electrode reaction reversibility, the difficult extent of oxygen evolution, the proton diffusion coefficient, the discharge potential of middle value and the active material utilization of the Ni(OH)2 film electrode were compared with those of the ones doped with the metal ions by means of cyclic voltammetry, potential step and constant current charge-discharge experiments. It was found that Ca2+, Co2+, Cd2+, Al3+ etc. have obviously positive effect.

  12. Effect of Alkali Ions on the Amorphous to Crystalline Phase Transition of Silica

    Science.gov (United States)

    Venezia, A. M.; La Parola, V.; Longo, A.; Martorana, A.

    2001-11-01

    The effect of the addition of alkali ions to commercial amorphous silica, generally used as support for heterogeneous catalysts, has been investigated from the point of view of morphological and structural changes. Samples of alkali-doped silica were prepared by impregnation and subsequent calcination at various temperatures. The structural effect of Li, Na, K, and Cs was determined by use of techniques such as wide-angle (WAXS) and small-angle X-ray scattering (SAXS). The WAXS diffractograms, analyzed with the Rietveld method using the GSAS program, allowed qualitative and quantitative identification of the fraction of the different silica polymorphs like quartz, tridymite, and cristobalite. SAXS measurements, using the classical method based on Porod's law, yielded the total surface area of the systems. The calculated areas were compared with the surface areas determined by the nitrogen adsorption technique using the analytical method of Brunauer-Emmett-Teller. The results are explained in terms of sizes of the alkali ions and cell volume of the different crystalline phases.

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

    Science.gov (United States)

    Sondhi, Sonica; Sharma, Prince; Saini, Shilpa; Puri, Neena; Gupta, Naveen

    2014-01-01

    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.

  14. Electrodeposition of alkali and alkali-earth metals on liquid lead cathodes in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Caravaca, C.; De Cordoba, G. [CIEMAT/DE/DFN/URAA. Avda. Complutense, 22. 28040 Madrid (Spain)

    2008-07-01

    Pyrochemical processing of spent nuclear fuel leads to the dissolution as chlorides of fission products (FPs) that have to be removed in order to recycle the salt. Precipitation technique have been tested for the removal of these FPs in the LiCl-KCl, salt selected as reference, with different results. Salt decontamination from lanthanides can be easily achieved as solid precipitates of oxychlorides or single phosphates; however, for the alkaline and alkaline-earth metals this technique is not suitable. Within the EUROPART project (VI FP of the EC), a new route that consist of the electrodeposition of these FP on a liquid lead cathode (LLC) has been considered, including the Li and K constituting the electrolyte. First results obtained with Sr and Cs are presented herein. Although according to the thermodynamic potential values, the electrodeposition order on LLC is Ba, Sr, Li, K and Cs, during our experiments it was not possible to distinguish the electrochemical signals corresponding to the individual elements. (authors)

  15. Ab Initio Molecular Dynamics of Dimerization and Clustering in Alkali Metal Vapors.

    Science.gov (United States)

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-06-30

    Alkali metals are known to form dimers, trimers, and tetramers in their vapors. The mechanism and regularities of this phenomenon characterize the chemical behavior of the first group elements. We report ab initio molecular dynamics (AIMD) simulations of the alkali metal vapors and characterize their structural properties, including radial distribution functions and atomic cluster size distributions. AIMD confirms formation of Men, where n ranges from 2 to 4. High pressure sharply favors larger structures, whereas high temperature decreases their fraction. Heavier alkali metals maintain somewhat larger fractions of Me2, Me3, and Me4, relative to isolated atoms. A single atom is the most frequently observed structure in vapors, irrespective of the element and temperature. Due to technical difficulties of working with high temperatures and pressures in experiments, AIMD is the most affordable method of research. It provides valuable understanding of the chemical behavior of Li, Na, K, Rb, and Cs, which can lead to development of new chemical reactions involving these metals.

  16. 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

  17. Development of a surface ionization source for the production of radioactive alkali ion beams in SPIRAL

    Energy Technology Data Exchange (ETDEWEB)

    Eleon, C. [GANIL, CEA/DSM CNRS/IN2P3, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France)], E-mail: sceleon@triumf.ca; Jardin, P.; Gaubert, G.; Saint-Laurent, M.-G.; Alcantara-Nunez, J.; Alves Conde, R.; Barue, C.; Boilley, D.; Cornell, J. [GANIL, CEA/DSM CNRS/IN2P3, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France); Delahaye, P. [3 CERN ISOLDE, 1211 Geneva 23 (Switzerland); Dubois, M.; Jacquot, B.; Leherissier, P.; Leroy, R.; Lhersonneau, G. [GANIL, CEA/DSM CNRS/IN2P3, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France); Marie-Jeanne, M. [3 CERN ISOLDE, 1211 Geneva 23 (Switzerland); Maunoury, L. [CIRIL, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France); Pacquet, J.Y.; Pellemoine, F. [GANIL, CEA/DSM CNRS/IN2P3, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France); Pierret, C. [CIRIL, Bd H. Becquerel, BP 55027, 14076 CAEN cedex 5 (France)] (and others)

    2008-10-15

    In the framework of the production of radioactive alkali ion beams by the isotope separation on-line (ISOL) method in SPIRAL I, a surface ionization source has been developed at GANIL to produce singly-charged ions of Li, Na and K. This new source has been designed to work in the hostile environment whilst having a long lifetime. This new system of production has two ohmic heating components: the first for the target oven and the second for the ionizer. The latter, being in carbon, offers high reliability and competitive ionization efficiency. This surface ionization source has been tested on-line using a {sup 48}Ca primary beam at 60.3 A MeV with an intensity of 0.14 pA. The ionization efficiencies obtained for Li, Na and K are significantly better than the theoretical values of the ionization probability per contact. The enhanced efficiency, due to the polarization of the ionizer, is shown to be very important also for short-lived isotopes. In the future, this source will be associated with the multicharged electron-cyclotron-resonance (ECR) ion source NANOGAN III for production of multicharged alkali ions in SPIRAL. The preliminary tests of the set up are also presented in this contribution.

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

    Science.gov (United States)

    Lutz, Jesse J; Hutson, Jeremy M

    2014-01-07

    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.

  19. "Doubly magic" conditions in magic-wavelength trapping of ultracold alkali-metal atoms.

    Science.gov (United States)

    Derevianko, Andrei

    2010-07-16

    In experiments with trapped atoms, atomic energy levels are shifted by the trapping optical and magnetic fields. Regardless of this strong perturbation, precision spectroscopy may be still carried out using specially crafted, "magic" trapping fields. Finding these conditions for particularly valuable microwave transitions in alkali-metal atoms has so far remained an open challenge. Here I demonstrate that the microwave transitions in alkali-metal atoms may be indeed made impervious to both trapping laser intensity and fluctuations of magnetic fields. I consider driving multiphoton transitions between the clock levels and show that these "doubly magic" conditions are realized at special values of trapping laser wavelengths and fixed values of relatively weak magnetic fields. This finding has implications for precision measurements and quantum information processing with qubits stored in hyperfine manifolds.

  20. Theory of metal atom-water interactions and alkali halide dimers

    Science.gov (United States)

    Jordan, K. D.; Kurtz, H. A.

    1982-01-01

    Theoretical studies of the interactions of metal atoms with water and some of its isoelectronic analogs, and of the properties of alkali halides and their aggregates are discussed. Results are presented of ab initio calculations of the heats of reaction of the metal-water adducts and hydroxyhydrides of Li, Be, B, Na, Mg, and Al, and of the bond lengths and angles an; the heats of reaction for the insertion of Al into HF, H2O, NH3, H2S and CH3OH, and Be and Mg into H2O. Calculations of the electron affinities and dipole moments and polarizabilities of selected gas phase alkali halide monomers and dimers are discussed, with particular attention given to results of calculations of the polarizability of LiF taking into account electron correlation effects, and the polarizability of the dimer (LiF)2.

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. Rational Design of Metal Ion Sequestering Agents

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, Kenneth N.; Xu, Jide; Gramer, Christine

    1999-06-01

    This project addresses the fundamental issues and requirements for developing hazardous metal ion separation technologies applicable to the treatment and disposal of radioactive waste. Our research encompasses the following areas: the design and synthesis of metal ion specific sequestering ligands, structural and thermodynamic investigations of these ligand and the complexes formed with targeted metal ions, and the development and incorporation of these ligands into applied separation technologies as highly effective materials for hazardous metal ion decontamination.

  6. Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells Using Surface Science Techniques

    OpenAIRE

    Seltzer, S. J.; Michalak, D. J.; Donaldson, M. H.; Balabas, M. V.; Barber, S. K.; Bernasek, S. L.; Bouchiat, M. -A.; Hexemer, A.; Hibberd, A. M.; Kimball, D. F. Jackson; C. Jaye; Karaulanov, T.; Narducci, F. A.; Rangwala, S. A.; Robinson, H. G.

    2010-01-01

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of anti-relaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10,000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the stu...

  7. Investigation of anti-Relaxation coatings for alkali-metal vapor cells using surface science techniques

    OpenAIRE

    Seltzer, S. J.

    2011-01-01

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10?000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the stud...

  8. Orbital Magnetism and Dynamics in Alkali Metal Clusters

    CERN Document Server

    Nesterenko, V O; De Souza-Cruz, F F; Marinelli, J R

    2000-01-01

    Two remarkable orbital magnetic resonances, M1 scissor mode and M2 twist mode, are predicted in deformed and spherical metal clusters, respectively. We show that these resonances provide a valuable information about many cluster properties (quadrupole deformation, magnetic susceptibility, single-particle spectrum, etc.)

  9. Metal ion binding with carbon nanotubes and graphene: Effect of chirality and curvature

    Science.gov (United States)

    Umadevi, Deivasigamani; Sastry, G. Narahari

    2012-10-01

    First principles calculations have been used to comprehensively study the binding of a series alkali (Li+, Na+, K+) and alkaline earth (Be2+, Mg2+, Ca2+) metal ions with carbon nanotubes (CNTs) and graphene. It is interesting to note that the mono-cationic systems prefer binding to armchair CNTs over zigzag CNTs, while the preference for the di-cationic systems is exactly opposite. We have also observed significant changes in the HOMO-LUMO energy gap of the CNTs on metal ion binding and these results indicate that the fine tuning of energy gap of the CNTs can be effected through metal ion binding.

  10. Alkali metal and simple gas atom adsorption and coadsorption on transition metal surfaces

    CERN Document Server

    Norris, A G

    2000-01-01

    system is formed by adsorption of potassium or cesium on the Ni(100)c(2x2)-O overlayer. The difficulty of the structural fit is compounded' by the size of the unit cell. In this study, Anomalous Scattering was used to investigate whether there is a contribution from the nickel substrate to the reconstruction. Measurements of the fractional order rods at 10 eV and 200 eV below the nickel K edge (8333 eV) showed no discernible differences and involvement of the nickel substrate in the reconstruction can be eliminated. Alkali metal coadsorption systems represent a step along the pathway from simple model adsorbate overlayers to more technologically relevant real systems. Such is their complexity, however, that very few systems have been solved structurally. Presented here are SXRD and STM investigations of two such systems. The first study involves potassium adsorption on the Ni(100)(2x2)p4g-N surface, where a clock reconstruction is present with the nickel substrate atoms rotated in alternate clockwise and anti...

  11. Spinel Metal Oxide-Alkali Carbonate-Based, Low-Temperature Thermochemical Cycles for Water Splitting and CO_2 Reduction

    OpenAIRE

    Xu, Bingjun; Bhawe, Yashodhan; Davis, Mark E.

    2013-01-01

    A manganese oxide-based, thermochemical cycle for water splitting below 1000 °C has recently been reported. The cycle involves the shuttling of Na+ into and out of manganese oxides via the consumption and formation of sodium carbonate, respectively. Here, we explore the combinations of three spinel metal oxides and three alkali carbonates in thermochemical cycles for water splitting and CO_2 reduction. Hydrogen evolution and CO_2 reduction reactions of metal oxides with a given alkali carbona...

  12. Effects of alkali ions on thermal stability and spectroscopic properties of Er{sup 3+}-doped gallogermanate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shi, D.M.; Zhao, Y.G.; Wang, X.F.; Liao, G.H. [Department of Materials Science and Engineering, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Zhao, C. [Department of Physics, South China University of Technology, Guangzhou 510641 (China); MOE Key Lab of Specially Functional Materials and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China); Peng, M.Y. [MOE Key Lab of Specially Functional Materials and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China); Zhang, Q.Y., E-mail: qyzhang@scut.edu.c [MOE Key Lab of Specially Functional Materials and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China)

    2011-02-01

    Since information transportation capacity of optical communication network increases rapidly, new optical materials are always demanded with gain bandwidth desirably much broader than traditional erbium-doped silica fiber amplifier (EDFA). We show here in this paper the erbium-doped gallogermanate glasses with a full-width at half-maximum (FWHM) more than 50 nm. Incorporation of alkali ions such as Li{sup +}, Na{sup +}, K{sup +} into the system can on the one hand improve the thermal stability of the glasses, and on the other hand enhance the emission at 1.5 {mu}m due to the {sup 4}I{sub 13/2{yields}}{sup 4}I{sub 15/2} transition of Er{sup 3+} and suppress the upconversion process at the same time. This particularly works best for the case of K{sup +} inclusion. This work might give a general idea on controlling the Er{sup 3+} luminescence by simply adjusting the glass component and find a potential laser glass applicable to developing new broadband fiber amplifier. -- Research highlights: {yields} We report on spectroscopic properties of Er{sup 3+}-doped Ga{sub 2}O{sub 3}-GeO{sub 2}-R{sub 2}O (GGR, R=Li, Na and K) glasses for 1.53 {mu}m fiber amplifier. Effects of alkali metal ions on the thermal stability and spectroscopic properties of Er{sup 3+}-doped GGR glasses have been investigated. {yields} Incorporation of alkali ions such as Li{sup +}, Na{sup +}, K{sup +} into the system can on the one hand improve the thermal stability of the glasses, and on the other hand enhance the emission at 1.5 {mu}m due to the {sup 4}I{sub 13/2{yields}}{sup 4}I{sub 15/2} transition of Er{sup 3+} and suppress the upconversion process at the same time. This particularly works best for the case of K{sup +} inclusion. This work might give a general idea on controlling the Er{sup 3+} luminescence by simply adjusting the glass component and find a potential laser glass applicable to developing new broadband fiber amplifier.

  13. Synthesis and Crystal Structure of A New Armed-tetraazacrown Ether and Its Liquid Membrane Transport of Alkali Metal Cations

    Institute of Scientific and Technical Information of China (English)

    马淑兰; 朱文祥; 董淑静; 郭倩玲; 佘远斌

    2003-01-01

    A new tetra-N-substituted tetraazacrown ether derivative, 4,7,13,16-tetra ( 2-cyanobenzyl)-1, 10-dioxa-4, 7, 13, 16-tetraazacy-dooctademne, C44H48N8O2, has been synthesized and struc-turally characterized. It crystallizes in the monoclinic system,Slmeegroup P21/c with a = 1.1176(3) nm, b =2.1906(7) nm,c=0.8430(3)nm, V=2.0132(10)nm3, β = 102.740(5)°,Z=4, Dc= 1.189 g/cm3, final R1=0.0460, wR2=0.0803.The liquid membrane transports of alkali metal cations using the new macrocyde as the ion-carrier were also studied. Com-pared with some macrocyclic ligands, our newly synthesized lig.and showed a good selectivity ratio for Na Na+/Li+.

  14. Alkali Metal Halide Salts as Interface Additives to Fabricate Hysteresis-Free Hybrid Perovskite-Based Photovoltaic Devices.

    Science.gov (United States)

    Wang, Lili; Moghe, Dhanashree; Hafezian, Soroush; Chen, Pei; Young, Margaret; Elinski, Mark; Martinu, Ludvik; Kéna-Cohen, Stéphane; Lunt, Richard R

    2016-09-07

    A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells.

  15. Alkali-metal ion coordination in uranyl(VI) poly-peroxo complexes in solution, inorganic analogues to crown-ethers. Part 2. Complex formation in the tetramethyl ammonium-, Li(+)-, Na(+)- and K(+)-uranyl(VI)-peroxide-carbonate systems.

    Science.gov (United States)

    Zanonato, Pier Luigi; Szabó, Zoltán; Vallet, Valerie; Di Bernardo, Plinio; Grenthe, Ingmar

    2015-10-01

    The constitution and equilibrium constants of ternary uranyl(vi) peroxide carbonate complexes [(UO2)p(O2)q(CO3)r](2(p-q-r)) have been determined at 0 °C in 0.50 M MNO3, M = Li, K, and TMA (tetramethyl ammonium), ionic media using potentiometric and spectrophotometric data; (17)O NMR data were used to determine the number of complexes present. The formation of cyclic oligomers, "[(UO2)(O2)(CO3)]n", n = 4, 5, 6, with different stoichiometries depending on the ionic medium used, suggests that Li(+), Na(+), K(+) and TMA ions act as templates for the formation of uranyl peroxide rings where the uranyl-units are linked by μ-η(2)-η(2) bridged peroxide-ions. The templating effect is due to the coordination of the M(+)-ions to the uranyl oxygen atoms, where the coordination of Li(+) results in the formation of Li[(UO2)(O2)(CO3)]4(7-), Na(+) and K(+) in the formation of Na/K[(UO2)(O2)(CO3)]5(9-) complexes, while the large tetramethyl ammonium ion promotes the formation of two oligomers, TMA[(UO2)(O2)(CO3)]5(9-) and TMA[(UO2)(O2)(CO3)]6(11-). The NMR spectra demonstrate that the coordination of Na(+) in the five- and six-membered oligomers is significantly stronger than that of TMA(+); these observations suggest that the templating effect is similar to the one observed in the synthesis of crown-ethers. The NMR experiments also demonstrate that the exchange between TMA[(UO2)(O2)(CO3)]5(9-) and TMA[(UO2)(O2)(CO3)]6(11-) is slow on the (17)O chemical shift time-scale, while the exchange between TMA[(UO2)(O2)(CO3)]6(11-) and Na[(UO2)(O2)(CO3)]6(11-) is fast. There was no indication of the presence of large clusters of the type identified by Burns and Nyman (M. Nyman and P. C. Burns, Chem. Soc. Rev., 2012, 41, 7314-7367) and possible reasons for this and the implications for the synthesis of large clusters are briefly discussed.

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

    Science.gov (United States)

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

    2016-04-05

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

  17. 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.

  18. The Effect of Alkali and Ce(III Ions on the Response Properties of Benzoxazine Supramolecules Prepared via Molecular Assembly

    Directory of Open Access Journals (Sweden)

    Apirat Laobuthee

    2012-01-01

    Full Text Available A series of benzoxazine monomer supramolecules with different substituted groups on their benzene ring was prepared with a Mannich reaction and characterized by FTIR, 1H-NMR and MS. The obtained products were 3,4-dihydro-3-(2’-hydroxyethylene-6-methyl-2H-benzoxazine (BM1, 3,4-dihydro-3-(2’-hydroxyethylene-6-ethyl-2H-benz-oxazine (BM2, and 3,4-dihydro-3-(2’-hydroxyethylene-6-methoxy-2H-benzoxazine (BM3. The efficiency of alkali metal ion extraction from the products was determined with Pedersen’s technique, while the complexation of the Ce(III ion was confirmed by the Job’s and the mole ratio methods. The evidence of complex formation between benzoxazine monomers and Ce(III ions was obtained with FTIR and a computational simulation. Single phase ceria (CeO2 as observed with XRD was successfully prepared by calcinating the Ce(III-benzoxazine monomer complexes at 600 °C for 2 h. In addition, the geometry of the ceria nanoparticles confirmed by TEM is spherical, with an average diameter of 10‑20 nm.

  19. Unraveling the absorption spectra of alkali metal atoms attached to helium nanodroplets.

    Science.gov (United States)

    Bünermann, Oliver; Droppelmann, Georg; Hernando, Alberto; Mayol, Ricardo; Stienkemeier, Frank

    2007-12-13

    The absorption spectra of the first electronic exited state of alkali metal atoms on helium nanodroplets formed of both 4He and 3He isotopes were studied experimentally as well as theoretically. In the experimental part new data on the 2palkali metal atoms with helium nanodroplets, a model calculation was performed. New helium density profiles as well as a refined model allowed us to achieve good agreement with the experimental findings. For the first time the red-shifted intensities in the lithium and sodium spectra are explained in terms of enhanced binding configurations in the excited state displaced spatially from the ground state configurations.

  20. A curious interplay in the films of N-heterocyclic carbene Pt(II) complexes upon deposition of alkali metals.

    Science.gov (United States)

    Makarova, Anna A; Grachova, Elena V; Niedzialek, Dorota; Solomatina, Anastasia I; Sonntag, Simon; Fedorov, Alexander V; Vilkov, Oleg Yu; Neudachina, Vera S; Laubschat, Clemens; Tunik, Sergey P; Vyalikh, Denis V

    2016-05-06

    The recently synthesized series of Pt(II) complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned Pt(II) complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination Pt(II) centre to Pt(0) and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system "Pt complex-alkali metal ion"; the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the Pt(II) complexes for a variety of biomedical, sensing, chemical, and electronic applications.

  1. Cyclic peptides-assisted trans- port of metal ions across liquid-organic membrane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The formation of alkali and alkaline-earth metal picrate complexes with cyclo(Pro-Gly)n ionophores (1, n = 3; 2, n = 4) can facilitate the migration of metal ions across a bulk liquid CH2Cl2 membrane. The migration behavior was studied by measuring the solution absorption at 356 nm, using a UV/Vis spectrophotometer, and the rates can be determined by comparing the initial absorption of donor solutions with the absorption of the corresponding receiver solutions as the function of time. It was found that cyclic peptide 1 shows higher transport activity for the studied alkali and alkaline-earth metal ions than compound 2, which is related to the backbone flexibility of the cyclic peptides. The findings in this work suggest that the rate of ionophore-facilitated ion transport depends not only on the ability of complex forma-tion in aqueous phase, but also on the ability of complex dissociation in organic phase.

  2. Multiheteromacrocycles that Complex Metal Ions. Sixth Progress Report, 1 May 1979-30 April 1980

    Science.gov (United States)

    Cram, D. J.

    1980-01-15

    Objective is to design synthesize, and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; number of binding sites; character of binding sites; and valences. During this period, hemispherands based on an aryloxy or cyclic urea unit, spherands based on aryloxyl units only, and their complexes with alkali metals and alkaline earths were investigated. An attempt to separate {sup 6}Li and {sup 7}Li by gel permeation chromatography of lithiospherium chloride failed. (DLC)

  3. Alkali metal mediated C-C bond coupling reaction.

    Science.gov (United States)

    Tachikawa, Hiroto

    2015-02-14

    Metal catalyzed carbon-carbon (C-C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz)2, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz)2, the structure of [Li(Bz)2](-) was drastically changed: Bz-Bz parallel form was rapidly fluctuated as a function of time, and a new C-C single bond was formed in the C1-C1' position of Bz-Bz interaction system. In the hole capture, the intermolecular vibration between Bz-Bz rings was only enhanced. The mechanism of C-C bond formation in the electron capture was discussed on the basis of theoretical results.

  4. Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells Using Surface Science Techniques

    CERN Document Server

    Seltzer, S J; Donaldson, M H; Balabas, M V; Barber, S K; Bernasek, S L; Bouchiat, M -A; Hexemer, A; Hibberd, A M; Kimball, D F Jackson; Jaye, C; Karaulanov, T; Narducci, F A; Rangwala, S A; Robinson, H G; Voronov, D L; Yashchuk, V V; Pines, A; Budker, D

    2010-01-01

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of anti-relaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10,000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We present a survey of modern surface science techniques applied to the study of paraffin coatings, in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge X-ray absorption fine structure spectroscopy, and X-ray photoelectron spectroscopy. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present with...

  5. Impurity detection in alkali-metal vapor cells via nuclear magnetic resonance

    Science.gov (United States)

    Patton, B.; Ishikawa, K.

    2016-11-01

    We use nuclear magnetic resonance spectroscopy of alkali metals sealed in glass vapor cells to perform in situ identification of chemical contaminants. The alkali Knight shift varies with the concentration of the impurity, which in turn varies with temperature as the alloy composition changes along the liquidus curve. Intentional addition of a known impurity validates this approach and reveals that sodium is often an intrinsic contaminant in cells filled with distilled, high-purity rubidium or cesium. Measurements of the Knight shift of the binary Rb-Na alloy confirm prior measurements of the shift's linear dependence on Na concentration, but similar measurements for the Cs-Na system demonstrate an unexpected nonlinear dependence of the Knight shift on the molar ratio. This non-destructive approach allows monitoring and quantification of ongoing chemical processes within the kind of vapor cells which form the basis for precise sensors and atomic frequency standards.

  6. Structural and Dynamical Trends in Alkali-Metal Silanides Characterized by Neutron-Scattering Methods

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Wan Si; Dimitrievska, Mirjana; Chotard, Jean-Noel; Zhou, Wei; Janot, Raphael; Skripov, Alexander V.; Udovic, Terrence J.

    2016-09-29

    Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH3, where M = K, Rb, Cs, K0.5Rb0.5, K0.5Cs0.5, and Rb0.5Cs0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron vibrational spectroscopy (NVS), neutron-scattering fixed-window scans (FWSs), and quasielastic neutron scattering (QENS) measurements. Structural characterization showed that the mixed compounds exhibit disordered (..alpha..) and ordered (..beta..) phases for temperatures above and below about 200-250 K, respectively, in agreement with their monoalkali correspondents. Vibrational and dynamical properties are strongly influenced by the cation environment; in particular, there is a red shift in the band energies of the librational and bending modes with increasing lattice size as a result of changes in the bond lengths and force constants. Additionally, slightly broader spectral features are observed in the case of the mixed compounds, indicating the presence of structural disorder caused by the random distribution of the alkali-metal cations within the lattice. FWS measurements upon heating showed that there is a large increase in reorientational mobility as the systems go through the order-disorder (..beta..-..alpha..) phase transition, and measurements upon cooling of the ..alpha..-phase revealed the known strong hysteresis for reversion back to the ..beta..-phase. Interestingly, at a given temperature, among the different alkali silanide compounds, the relative reorientational mobilities of the SiH3- anions in the ..alpha..- and ..beta..-phases tended to decrease and increase, respectively, with increasing alkali-metal mass. This dynamical result might provide some insights concerning the enthalpy-entropy compensation effect previously observed for these potentially promising hydrogen storage materials.

  7. Lithium tracer-diffusion in an alkali-basaltic melt — An ion-microprobe determination

    Science.gov (United States)

    Lowry, R. K.; Reed, S. J. B.; Nolan, J.; Henderson, P.; Long, J. V. P.

    1981-03-01

    An ion-microprobe-based technique has been used to measure lithium tracer-diffusion coefficients ( D Li) in an alkali-basaltic melt at 1300, 1350 and 1400°C. The results can be expressed in the form: D Li=7.5 ×10 -2exp(-27,600/RT)cm 2S -1 The results show significantly faster diffusion rates than those previously recorded for other monovalent, divalent and trivalent cations in a tholeiitic melt. Consequently, diffusive transport of ions acting over a given time in a basaltic melt can produce a wider range of transport distance values than hitherto supposed. Hence, it is concluded that great care should be exercised when applying diffusion data to petrological problems.

  8. Subtask 12E1: Compatibility of structural materials in liquid alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L.; Haglund, R.; Clark, R.W. [Argonne National Lab., IL (United States)

    1995-03-01

    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 that are in the range of interest for the 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. Candidate structural materials are being evaluated for their compatibility, interstitial-element transfer, and corrosion in liquid alkali-metal systems such as lithium and NaK. Type 316 stainless steel and V-5Cr-5Ti coupon specimens with and without prealuminizing treatment have been exposed to NaK and lithium environments of commercial purity for times up to 3768 h at temperatures between 300 and 400{degrees}C. 13 refs., 8 figs., 3 tabs.

  9. Tris-[8]annulenyl Isocyanurate Trianion Triradical and Hexa-anion from the Alkali Metal Reduction of [8]Annulenyl Isocyanate.

    Science.gov (United States)

    Peters, Steven J; Klen, Joseph R

    2015-06-05

    The solution phase alkali metal reduction of [8]annulenyl isocyanate (C8H7NCO) yields an EPR spectrum, which reveals electron couplings to seven protons and only one nitrogen. Although this strongly suggested that the C8H7NCO anion radical was generated, experiments on the oxidized product reveal the actual reduced species to be tris-[8]annulenyl isocyanurate. Unlike the previously studied phenyl isocyanurate anion radical, the unpaired electron(s) is now localized within an [8]annulenyl moiety. Further exposure to metal results in the formation of an equilibrium mixture of trianion triradical and trianion radical species. The cyclotrimerization to form the isocyanurate is proposed to be driven by a reactive C8H7NCO dianion, which is produced from the large equilibrium disproportionation of the anion radical. Exhaustive reduction of the tris-[8]annulenyl isocyanurate with potassium in THF generates the first-ever observed hexa-anion of an isocyanurate. NMR analysis reveals that the polarity of the carbonyl bonds within this hexa-anion is augmented and is caused by the close proximity of K(+) ions, which are tightly ion paired to the three [8]annulenyl dianion rings. These preliminary studies on the reduction of C8H7NCO suggest that polymeric materials (e.g., polyisocyanates) made from this isocyanate might exhibit unique properties.

  10. Metal ions, Alzheimer's disease and chelation therapy.

    Science.gov (United States)

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases.

  11. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, Richard A.

    2012-06-04

    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  12. 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)

  13. 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.

  14. Thermochemical ablation therapy of VX2 tumor using a permeable oil-packed liquid alkali metal.

    Directory of Open Access Journals (Sweden)

    Ziyi Guo

    Full Text Available Alkali metal appears to be a promising tool in thermochemical ablation, but, it requires additional data on safety is required. The objective of this study was to explore the effectiveness of permeable oil-packed liquid alkali metal in the thermochemical ablation of tumors.Permeable oil-packed sodium-potassium (NaK was prepared using ultrasonic mixing of different ratios of metal to oil. The thermal effect of the mixture during ablation of muscle tissue ex vivo was evaluated using the Fluke Ti400 Thermal Imager. The thermochemical effect of the NaK-oil mixture on VX2 tumors was evaluated by performing perfusion CT scans both before and after treatment in 10 VX2 rabbit model tumors. VX2 tumors were harvested from two rabbits immediately after treatment to assess their viability using trypan blue and hematoxylin and eosin (H.E. staining.The injection of the NaK-oil mixture resulted in significantly higher heat in the ablation areas. The permeable oil controlled the rate of heat released during the NaK reaction with water in the living tissue. Perfusion computed tomography and its parameter map confirmed that the NaK-oil mixture had curative effects on VX2 tumors. Both trypan blue and H.E. staining showed partial necrosis of the VX2 tumors.The NaK-oil mixture may be used successfully to ablate tumor tissue in vivo. With reference to the controlled thermal and chemical lethal injury to tumors, using a liquid alkali in ablation is potentially an effective and safe method to treat malignant tumors.

  15. 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.

  16. Electric dipole polarizabilities of Rydberg states of alkali-metal atoms

    Science.gov (United States)

    Yerokhin, V. A.; Buhmann, S. Y.; Fritzsche, S.; Surzhykov, A.

    2016-09-01

    Calculations of the static electric-dipole scalar and tensor polarizabilities are presented for two alkali-metal atoms, Rb and Cs, for the n S , n P½,3 /2 , and n D3 /2 ,5 /2 states with large principal quantum numbers up to n =50 . The calculations are performed within an effective one-electron approximation, based on the Dirac-Fock Hamiltonian with a semiempirical core-polarization potential. The obtained results are compared with those from a simpler semiempirical approach and with available experimental data.

  17. Antiproton and proton collisions with the alkali-metal atoms Li, Na, and K

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2008-01-01

    Single-electron ionization and excitation cross sections as well as cross sections for excitation into the first excited p state of the alkali-metal atoms Li(2s), Na(3s), and K(4s) colliding with antiprotons and protons were calculated using a time-dependent channel-coupling approach....... For antiprotons an impact-energy range from 0.25 to 1000 keV and for protons from 2 to 1000 keV was considered. The target atoms are treated as effective one-electron systems using a model potential. The results are compared with theoretical and experimental data from literature and calculated cross sections...

  18. 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.

  19. Shortcuts for understanding rovibronic spectroscopy of ultracold alkali metal diatomic molecules

    Science.gov (United States)

    Stwalley, William C.; Bellos, Michael; Carollo, Ryan; Banerjee, Jayita; Bermudez, Matthew

    2012-08-01

    The high-resolution rovibronic spectroscopies of cold and ultracold molecules (e.g. supersonic molecular beam excitation spectra (MB), photoassociation spectra of ultracold atoms (PA), resonance-enhanced multiphoton ionization spectra (REMPI), stimulated Raman transfer (SRT) spectra) are of major current interest. This manuscript summarizes the significant level of understanding of these various spectroscopies, enabled by using simple graphical and semiclassical ideas and shortcuts. Physical realizations of these spectroscopies will be illustrated using the alkali metal diatomic molecules, both homonuclear (e.g. Rb2) and heteronuclear (e.g. KRb).

  20. Metal Hydride and Alkali Halide Opacities in Extrasolar Giant Planets and Cool Stellar Atmospheres

    Science.gov (United States)

    Weck, Philippe F.; Stancil, Phillip C.; Kirby, Kate; Schweitzer, Andreas; Hauschildt, Peter H.

    2006-01-01

    The lack of accurate and complete molecular line and continuum opacity data has been a serious limitation to developing atmospheric models of cool stars and Extrasolar Giant Planets (EGPs). We report our recent calculations of molecular opacities resulting from the presence of metal hydrides and alkali halides. The resulting data have been included in the PHOENIX stellar atmosphere code (Hauschildt & Baron 1999). The new models, calculated using spherical geometry for all gravities considered, also incorporate our latest database of nearly 670 million molecular lines, and updated equations of state.

  1. Investigation of luminescence and spectroscopic properties of Nd3+ions in cadmium alkali borate glasses

    Science.gov (United States)

    Mohan, Shaweta; Thind, Kulwant Singh

    2016-07-01

    Neodymium doped cadmium alkali borate glasses having composition 20CdOsbnd 20R2Osbnd 59.5H3BO3sbnd 0.5Nd2O3; (R = Li, Na and K) were prepared by conventional melt-quenching technique. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical properties such as density, refractive index, molar volume, rare earth ion concentration etc. were determined. Optical absorption and fluorescence spectra were recorded. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. These parameters were in turn used to predict the radiative properties such as the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the fluorescent levels of Nd3+ ion in the present glass series. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. The variation of Ω2 with the change in alkali oxide has been attributed to the changes in the asymmetry of the ligand field at the rare earth ion site. The shift of the hypersensitive bands, study of the oscillator strengths and the variation of the spectral profile of the transition 4I9/2 → 4F7/2 + 4S3/2 indicate a maximum covalency of Ndsbnd O bond for glass with potassium ions. From the fluorescence spectra, peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) have been obtained for the three transitions 4F3/2 → 4I9/2,4F3/2 → 4I11/2 and4F3/2 → 4I13/2 of Nd3+ ion. The relatively high values of σp obtained for Nd3+ in present glass system suggest that these materials can be considered as suitable candidates for laser applications. The glass with potassium ions shows the highest value of the stimulated emission cross-section.

  2. The Production of Polycyclic Aromatic Hydrocarbon Anions in Inert Gas Matrices Doped with Alkali Metals. Electronic Absorption Spectra of the Pentacene Anion (C22H14(-))

    Science.gov (United States)

    Halasinski, Thomas M.; Hudgins, Douglas M.; Salama, Farid; Allamandola, Louis J.; Mead, Susan (Technical Monitor)

    1999-01-01

    The absorption spectra of pentacene (C22H14) and its radical cation (C22H14(+)) and anion (C22H14(-)) isolated in inert-gas matrices of Ne, Ar, and Kr are reported from the ultraviolet to the near-infrared. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing ion (and counterion) production in the solid matrix. In particular, the formation of isolated pentacene anions is found to be optimized in matrices doped with alkali metal (Na and K).

  3. Photon Hall Scattering from Alkaline-earth-like atoms and Alkali-like ions

    CERN Document Server

    van Tiggelen, B A

    2016-01-01

    We investigate the possibility of observing a magneto-transverse scattering of photons from alkaline-earth-like atoms as well as alkali-like ions and provide orders of magnitude. The transverse magneto-scattering is physically induced by the interference between two possible quantum transitions of an outer electron in a S-state, one dispersive electric-dipole transition to a P-orbital state and a second resonant electric-quadrupole transition to a P-orbital state. In contrast with previous mechanisms proposed for such an atomic photonic Hall effect, no real photons are scattered by the electric-dipole allowed transition, which increases the ratio of Hall current to background photons significantly. The main experimental challenge is to overcome the small detection threshold, with only 10^{-5} photons scattered per atom per second.

  4. First structural evidence for multiple alkali metals between sandwich decks in a metallocene.

    Science.gov (United States)

    Jeletic, Matthew; Perras, Frédéric A; Gorelsky, Serge I; Le Roy, Jennifer J; Korobkov, Ilia; Bryce, David L; Murugesu, Muralee

    2012-07-14

    A tetralithio salt (1) derived by treating 1,4-bis(trimethylsilyl)-cyclooctatriene with (n)BuLi serves as the first structural evidence for a multi-alkali metallocene. Single-crystal XRD confirms two Li(+) each asymmetrically bind to η(3) and η(4) between two COT'' rings and two Li(+) terminally bind to η(3). Solid-state NMR studies confirm the presence of two distinct lithium ion sites while the solution NMR studies suggest the formation of an (COT'' dianion) ion-pair in solution. Further treating of the tetralithio salt with NaCl leads to linear sodium polymeric chains. Therefore, simply changing the ionic radius changes the molecular structure.

  5. 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.;

    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...

  6. Direct surface charging and alkali-metal doping for tuning the interlayer magnetic order in planar nanostructures

    Science.gov (United States)

    Dasa, Tamene R.; Stepanyuk, Valeri S.

    2015-08-01

    The continuous reduction of magnetic units to ultrasmall length scales inspires efforts to look for a suitable means of controlling magnetic states. In this study, we show two surface charge alteration techniques for tuning the interlayer exchange coupling of ferromagnetic layers separated by paramagnetic spacers. Our ab initio study reveals that already a modest amount of extra charge can switch the mutual alignment of the magnetization from antiferromagnetic to ferromagnetic or vice versa. We also propose adsorption of alkali metals as an alternative way of varying the electronic and chemical properties of magnetic surfaces. Clear evidence is found that the interlayer magnetic order can be reversed by adsorbing alkali metals on the magnetic layer. Moreover, alkali-metal overlayers strongly enhance the perpendicular magnetic anisotropy in FePt thin films. These findings combined with atomistic spin model calculations suggest that the electronic or ionic way of surface charging can have a crucial role for magnetic hardening and spin state control.

  7. 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.

  8. 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

    2014-12-03

    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.

  9. 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.

  10. Challenges and Prospect of Non-aqueous Non-alkali (NANA) Metal-Air Batteries.

    Science.gov (United States)

    Gelman, Danny; Shvartsev, Boris; Ein-Eli, Yair

    2016-12-01

    Non-aqueous non-alkali (NANA) metal-air battery technologies promise to provide electrochemical energy storage with the highest specific energy density. Metal-air battery technology is particularly advantageous being implemented in long-range electric vehicles. Up to now, almost all the efforts in the field are focused on Li-air cells, but other NANA metal-air battery technologies emerge. The major concern, which the research community should be dealing with, is the limited and rather poor rechargeability of these systems. The challenges we are covering in this review are related to the initial limited discharge capacities and cell performances. By comprehensively reviewing the studies conducted so far, we show that the implementation of advanced materials is a promising approach to increase metal-air performance and, particularly, metal surface activation as a prime achievement leading to respectful discharge currents. In this review, we address the most critical areas that need careful research attention in order to achieve progress in the understanding of the physical and electrochemical processes in non-aqueous electrolytes applied in beyond lithium and zinc air generation of metal-air battery systems.

  11. The contents of alkali and alkaline earth metals in soils of the southern Cis-Ural region

    Science.gov (United States)

    Asylbaev, I. G.; Khabirov, I. K.

    2016-01-01

    The contents and distribution patterns of alkali and alkaline earth metals in soils and rocks of the southern Cis-Ural region were studied. A database on the contents of these metals was developed, the soils were classified with respect to their provision with these metals, and corresponding schematic maps showing their distribution in soils of the region were compiled. It was found that the contents of these metals decrease from east to west (from the Yuryuzan-Aisk Piedmont Plain to the Ufa Plateau and to the Belebeevsk Upland), and their distribution patterns change. Among alkali metals, the highest accumulation in the soils is typical of potassium, sodium, and cesium; among alkaline earth metals, of strontium and barium.

  12. 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.

  13. Metal Ion Controlled Polymorphism of a Peptide

    DEFF Research Database (Denmark)

    Hemmingsen, Lars Bo Stegeager; Jancso, Attila; Szunyogh, Daniel;

    2011-01-01

    , …) in the peptide, and the ligand and structural preferences of the metal ion (in our studies Zn2+, Cd2+, Hg2+, Cu+/2+). Simultaneously, new species such as metal ion bridged ternary complexes or even oligomers may be formed. In recent previous studies we have observed similar polymorphism of zinc finger model...

  14. Comparison of dissociation mechanism between collisionally activated dissociation and charge inversion using alkali metal targets for chlorophenol isomers

    Science.gov (United States)

    Hayakawa, Shigeo; Kawamura, Yoshiaki; Takahashi, Yutaka

    2005-11-01

    Chlorinated aromatic compounds are well-known environmental pollutants whose toxicities depend dramatically on the chlorine substitution pattern, making differentiation of chlorophenol isomers important for environmental analysis. Collisionally activated dissociation (CAD) spectra and charge inversion spectra of ortho-, meta-, and para-chlorophenols (ClC6H4OH) and their partially deuterated forms (ClC6H4OD) were measured using alkali metal targets. The peaks associated with C6H4O+ and C5H5Cl+ ions observed in the CAD spectra result from the loss of HCl and CO fragments, respectively, after the re-arrangement of the hydroxyl hydrogen atom. The peaks associated with C6H4OH- and ClC6H4O- ions observed in the charge inversion spectra result from Cl loss and from hydroxyl bond dissociation, respectively. Isomeric differentiation is possible based on the clear differences observed in the relative intensities of these pairs of peaks. Although the intensities of the peaks associated with C6H4O+ relative to those of C5H5Cl+ in the CAD spectra are independent of the target species, the intensities of the peaks associated with C6H4OH- relative to those of ClC6H4O- in the charge inversion spectra are target dependent. The isomeric dependence of the positive ion distribution patterns in the CAD spectra is proposed to be due to the differences in the rate of the hydrogen atom re-arrangement process. In contrast, the isomeric dependence of the negative ion distribution patterns in the charge inversion spectra is attributed to differences in the bond strength involved in the direct dissociation process in the neutral intermediate species.

  15. Static and Dynamic Structure Factors with Account of the Ion Structure for High-temperature Alkali and Alkaline Earth Plasmas

    CERN Document Server

    Sadykova, S P; Tkachenko, I M

    2010-01-01

    The $e-e$, $e-i$, $i-i$ and charge-charge static structure factors are calculated for alkali and Be$^{2+}$ plasmas using the method described by Gregori et al. in \\cite{bibGreg2006}. The dynamic structure factors for alkali plasmas are calculated using the method of moments \\cite{bibAdam83}, \\cite{bibAdam93}. In both methods the screened Hellmann-Gurskii-Krasko potential, obtained on the basis of Bogolyubov's method, has been used taking into account not only the quantum-mechanical effects but also the ion structure \\cite{bib73}. PACS: 52.27.Aj (Alkali and alkaline earth plasmas, Static and dynamic structure factors), 52.25.Kn (Thermodynamics of plasmas), 52.38.Ph (X-ray scattering)

  16. Intercalation Pseudocapacitance in Ultrathin VOPO4 Nanosheets: Toward High-Rate Alkali-Ion-Based Electrochemical Energy Storage.

    Science.gov (United States)

    Zhu, Yue; Peng, Lele; Chen, Dahong; Yu, Guihua

    2016-01-13

    There is a growing need for energy storage devices in numerous applications where a large amount of energy needs to be either stored or delivered quickly. The present paper details the study of alkali-ion intercalation pseudocapacitance in ultrathin VOPO4 nanosheets, which hold promise in high-rate alkali-ion based electrochemical energy storage. Starting from bulk VOPO4·2H2O chunks, VOPO4 nanosheets were obtained through simple ultrasonication in 2-propanol. These nanosheets as the cathode exhibit a specific capacity of 154 and 136 mAh/g (close to theoretical value 166 mAh/g) for lithium and sodium storage devices at 0.1 C and 100 and ∼70 mAh/g at 5 C, demonstrating their high rate capability. Moreover, the capacity retention is maintained at 90% for lithium ion storage and 73% for sodium ion storage after 500 cycles, showing their reasonable stability. The demonstrated alkali-ion intercalation pseudocapacitance represents a promising direction for developing battery materials with promising high rate capability.

  17. Nature of the Charge Localized Between Alkali Adatoms and Metal Substrates

    OpenAIRE

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

    1994-01-01

    Two previously unappreciated features in photoemission spectra from alkali atoms adsorbed on W(110), namely, the sign of the alkali-induced surface-atom core-level shift of the substrate at low coverage and the very large alkali shallow core-hole lifetime width at all coverages, show that the alkali-substrate interaction is not well described by a transfer of alkali charge. Instead, both features point to the formation of a charge cloud between the alkali adatom and substrate that is d...

  18. METALLIC PHASE AND INSULATING CHARACTER OF ALKALI-EARTH METAL DOPED C60

    Institute of Scientific and Technical Information of China (English)

    曹阳; 陈良进; 陈波; 冯建文; 陈文建

    1995-01-01

    The three dimensional EHMO crystal orbital calculations for crystalline Ba6 C60,Ca3 C60 and Ca5 C60 are reported.The ground state of partially doped Ca3 C60 is found to be insulating with an indrect energy gap of 0.5eV.In contrast,the Ca5 C60 forms a metallic conducting phase with a set of three half-filled bands crossing the Fermi level which is Found to locate close to a peak of the density of state. The character of crystal orbitals near the Fermilevel for both Ca3 C60 and Ca5 C60 is completely carbon-like.In both cases the Ca3 atoms are almost fully ionized and C60 molecules form a stable negative charge state with six to ten additional electrons.The conductivity of Ba6 C60 is resuted from the incomplete charge tranfer.The valance charge of every Ba ion is about 0.33.The total charge tranfer of six Ba atoms is almost the same as that of five Ca atoms.

  19. Investigation of anti-Relaxation coatings for alkali-metal vapor cells using surface science techniques

    Energy Technology Data Exchange (ETDEWEB)

    Seltzer, S. J.; Michalak, D. J.; Donaldson, M. H.; Balabas, M. V.; Barber, S. K.; Bernasek, S. L.; Bouchiat, M.-A.; Hexemer, A.; Hibberd, A. M.; Jackson Kimball, D. F.; Jaye, C.; Karaulanov, T.; Narducci, F. A.; Rangwala, S. A.; Robinson, H. G.; Shmakov, A. K.; Voronov, D. L.; Yashchuk, V. V.; Pines, A.; Budker, D.

    2010-10-11

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10?000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.

  20. Structures of Hydrated Alkali Metal Cations, M+(H2O)nAr (m = Li, Na, K, rb and Cs, n = 3-5), Using Infrared Photodissociation Spectroscopy and Thermodynamic Analysis

    Science.gov (United States)

    Ke, Haochen; van der Linde, Christian; Lisy, James M.

    2014-06-01

    Alkali metal cations play vital roles in chemical and biochemical systems. Lithium is widely used in psychiatric treatment of manic states and bipolar disorder; Sodium and potassium are essential elements, having major biological roles as electrolytes, balancing osmotic pressure on body cells and assisting the electroneurographic signal transmission; Rubidium has seen increasing usage as a supplementation for manic depression and depression treatment; Cesium doped compounds are used as essential catalysts in chemical production and organic synthesis. Since hydrated alkali metal cations are ubiquitous and the basic form of the alkali metal cations in chemical and biochemical systems, their structural and thermodynamic properties serve as the foundation for modeling more complex chemical and biochemical processes, such as ion transport and ion size-selectivity of ionophores and protein channels. By combining mass spectrometry and infrared photodissociation spectroscopy, we have characterized the structures and thermodynamic properties of the hydrated alkali metal cations, i.e. M+(H2O)nAr, (M = Li, Na, K, Rb and Cs, n = 3-5). Ab initio calculations and RRKM-EE (evaporative ensemble) calculations were used to assist in the spectral assignments and thermodynamic analysis. Results showed that the structures of hydrated alkali metal cations were determined predominantly by the competition between non-covalent interactions, i.e. the water---water hydrogen bonding interactions and the water---cation electrostatic interactions. This balance, however, is very delicate and small changes, i.e. different cations, different levels of hydration and different effective temperatures clearly impact the balance.

  1. Synthesis of Zeolite from Fly Ash and Removal of Heavy Metal Ions from Newly Synthesized Zeolite

    Directory of Open Access Journals (Sweden)

    Parag Solanki

    2010-01-01

    Full Text Available Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. Characteristics of the various Fly ash samples were carried out. Coal proximate analysis was done. Batch experiment was carried out for the adsorption of some heavy metal ions on to synthesized Zeolite. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

  2. Synthesis of Zeolite from Fly Ash and Removal of Heavy Metal Ions from Newly Synthesized Zeolite

    OpenAIRE

    Parag Solanki; Vikal Gupta; Ruchi Kulshrestha

    2010-01-01

    Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. Characteristics of the various Fly ash samples were carried out. Coal proximate analysis was done. Batch experiment was carried out for the adsorption of some heavy metal ions on to synthesized Zeolite. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

  3. Alkali metal salts of formazanate ligands : diverse coordination modes as a result of the nitrogen-rich [NNCNN] ligand backbone

    NARCIS (Netherlands)

    Travieso-Puente, Raquel; Chang, Mu-Chieh; Otten, Edwin

    2014-01-01

    Alkali metal salts of redox-active formazanate ligands were prepared, and their structures in the solid-state and in solution are determined. The nitrogen-rich [NNCNN] backbone of formazanates results in a varied coordination chemistry, with both the internal and terminal nitrogen atoms available fo

  4. Synthesis and Selective Coloration of Monoaza Crown Ethers Bearing Picrylamino-type Side Arms for Alkali Metal Salts and Methylamine

    Institute of Scientific and Technical Information of China (English)

    Wei ZENG; Zhi Hua MAO; Mi GONG; Chun Chun ZHANG; Sheng Ying QIN; Jun SU

    2003-01-01

    N-pivot lariat ethers with picrylamino group as a chromophore (1, 2 and 3) have been prepared by reaction of N-(4-aminoaryl)monoaza crown ethers with picryl chrolide, and the selective coloration of 1, 2 and 3 for alkali metal salts and amines has been studied by UV-Vis spectra.

  5. LDA or GGA? A combined experimental inelastic neutron scattering and ab initio lattice dynamics study of alkali metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, G.D. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Departamento de Quimica, Universidad Nacional de la Patagonia SJB, Ciudad Universitaria, 9005 Comodoro Rivadavia (Argentina); Colognesi, D. [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano s.n.c., 50019 Sesto Fiorentino (Finland) (Italy); Mitchell, P.C.H. [School of Chemistry, University of Reading, RG6 6AD (United Kingdom); Ramirez-Cuesta, A.J. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); School of Chemistry, University of Reading, RG6 6AD (United Kingdom)], E-mail: a.j.ramirez-cuesta@rl.ac.uk

    2005-10-31

    In a previous work, we carried out inelastic neutron scattering (INS) spectroscopy experiments and preliminary first principles calculations on alkali metal hydrides. The complete series of alkali metal hydrides, LiH, NaH, KH, RbH and CsH was measured in the high-resolution TOSCA INS spectrometer at ISIS. Here, we present the results of ab initio electronic structure calculations of the properties of the alkali metal hydrides using both the local density approximation (LDA) and the generalized gradient approximation (GGA), using the Perdew-Burke-Ernzerhof (PBE) parameterization. Properties calculated were lattice parameters, bulk moduli, dielectric constants, effective charges, electronic densities and inelastic neutron scattering (INS) spectra. We took advantage of the currently available computer power to use full lattice dynamics theory to calculate thermodynamic properties for these materials. For the alkali metal hydrides (LiH, NaH, KH, RbH and CsH) using lattice dynamics, we found that the INS spectra calculated using LDA agreed better with the experimental data than the spectra calculated using GGA. Both zero-point effects and thermal contributions to free energies had an important effect on INS and several thermodynamic properties.

  6. Magnetism in alkali-metal-doped wurtzite semiconductor materials controlled by strain engineering

    Science.gov (United States)

    Guo, J. H.; Li, T. H.; Liu, L. Z.; Hu, F. R.

    2016-09-01

    The study of the magnetism and optical properties of semiconductor materials by defect engineering has attracted much attention because of their potential uses in spintronic and optoelectronic devices. In this paper, first-principle calculations discloses that cationic vacancy formation energy of the doped wurtzite materials can be sharply decreased due to alkali metal dopants and shows that their magnetic properties strongly depend on defect and doping concentration. This effect can be ascribed to the volume change induced by foreign elements doped into the host system and atomic population's difference. The symmetric deformation induced by biaxial strain can further regulate this behavior. Our results suggest that the formation of cationic vacancy can be tailored by strain engineering and dopants incorporation.

  7. 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.

  8. Alkali-metal electron spin density shift induced by a helium nanodroplet

    Science.gov (United States)

    Koch, Markus; Callegari, Carlo; Ernst, Wolfgang E.

    2010-04-01

    Helium (He) nanodroplets provide a cold and virtually unperturbing environment for the study of weakly bound molecules and van der Waals aggregates. High resolution microwave spectroscopy and the detection of electron spin transitions in doped He droplets have recently become possible. Measurements of hyperfine-resolved electron spin resonance in potassium (39K) and rubidium (85Rb) atoms on the surface of He droplets show small line shifts relative to the bare atoms. These shifts were recorded for all 2I + 1 components (I is the nuclear spin) of a transition at high accuracy for He droplets ranging in size from 1000 to 15,000 He atoms. Evaluation of the spectra yields the influence of the He environment on the electron spin density at the alkali-metal nucleus. A semi-empirical model is presented that shows good qualitative agreement with the measured droplet size dependent increase of Fermi contact interaction at the nuclei of dopant K and Rb.

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

    Energy Technology Data Exchange (ETDEWEB)

    Belokoneva, E.L. [Moscow State Univ., Moscow (Russian Federation). Dept. of Crystallography and Crystal Chemistry

    2013-11-01

    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.)

  10. An analytical model of Faraday rotation in hot alkali metal vapours

    CERN Document Server

    Kemp, Stefan L; Cornish, Simon L

    2011-01-01

    We report a thorough investigation into the absorptive and dispersive properties of hot caesium vapour, culminating in the development of a simple analytical model for off-resonant Faraday rotation. The model, applicable to all hot alkali metal vapours, is seen to predict the rotation observed in caesium, at temperatures as high as 115 $^{\\circ}$C, to within 1% accuracy for probe light detuned by greater than 2 GHz from the $D_{2}$ lines. We also demonstrate the existence of a weak probe intensity limit, below which the effect of hyperfine pumping is negligible. Following the identification of this regime we validate a more comprehensive model for the absorption and dispersion in the vicinity of the $D_{2}$ lines, implemented in the form of a computer code. We demonstrate the ability of this model to predict Doppler-broadened spectra to within 0.5% rms deviation for temperatures up to 50 $^{\\circ}$C.

  11. 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.

  12. Alkali metal compatibility testing of candidate heater head materials for a Stirling engine heat transport system

    Science.gov (United States)

    Noble, Jack E.; Hickman, Gary L.; Grobstein, Toni

    The authors describe work performed as part of the 25-kWe advanced Stirling conversion system project. Liquid alkali metal compatibility is being assessed in an ongoing test program to evaluate candidate heater head materials and fabrication processes at the temperatures and operating conditions required for Stirling engines. Specific materials under evaluation are alloy 713LC, alloy 713LC coated with nickel aluminide, and Udimet 720, each in combination with Waspaloy. The tests were run at a constant 700 C. A eutectic alloy of sodium and potassium (NaK) was the working fluid. Titanium sheet in the system was shown to be an effective oxygen getter. Metallographic and microchemical examination of material surfaces, joints, and their interfaces revealed little or no corrosion after 1000 h. Tests are in progress, with up to 10,000 h exposure.

  13. Molecular dynamics simulations of the dynamic and energetic properties of alkali and halide ions using water-model-specific ion parameters.

    Science.gov (United States)

    Joung, In Suk; Cheatham, Thomas E

    2009-10-01

    The dynamic and energetic properties of the alkali and halide ions were calculated using molecular dynamics (MD) and free energy simulations with various different water and ion force fields including our recently developed water-model-specific ion parameters. The properties calculated were activity coefficients, diffusion coefficients, residence times of atomic pairs, association constants, and solubility. Through calculation of these properties, we can assess the validity and range of applicability of the simple pair potential models and better understand their limitations. Due to extreme computational demands, the activity coefficients were only calculated for a subset of the models. The results qualitatively agree with experiment. Calculated diffusion coefficients and residence times between cation-anion, water-cation, and water-anion showed differences depending on the choice of water and ion force field used. The calculated solubilities of the alkali-halide salts were generally lower than the true solubility of the salts. However, for both the TIP4P(EW) and SPC/E water-model-specific ion parameters, solubility was reasonably well-reproduced. Finally, the correlations among the various properties led to the following conclusions: (1) The reliability of the ion force fields is significantly affected by the specific choice of water model. (2) Ion-ion interactions are very important to accurately simulate the properties, especially solubility. (3) The SPC/E and TIP4P(EW) water-model-specific ion force fields are preferred for simulation in high salt environments compared to the other ion force fields.

  14. Recovery of metal ions by microfungal filters.

    Science.gov (United States)

    Wales, D S; Sagar, B F

    1990-01-01

    Many microfungi contain chitin/chitosan as an integral part of the cell wall structure. The binding of toxic and heavy metal ions by chitosan or partly deacetylated chitin is a direct consequence of the base strength of the primary amine group and is most effective for those metals that form complexes with ammonia. Of the microfungi studied, hyphae from Mucor mucedo and Rhizomucor miehei, after treatment with hydroxide to expose the chitin/chitosan, were found to be most effective in the capture of metal ions. Chemically treated mycelia have so far been shown to bind silver, zinc, lead, copper, nickel, cobalt, cadmium, iron and chromium, with the efficiency of metal-ion binding apparently being inversely proportional to the valency state of the metal ions to be bound. Wet-laid papers produced from mixed slurries of treated mycelia and various conventional paper-making and textile fibres have exceptionally good tensile- and bursting-strength properties, particularly in the wet state. Papers containing 1 g treated mycelia removed up to 90% of various metal ions in solution (50 cm3, 1.5 mmol dm-3) with flow rates of 0.5 cm3 cm-2 min-1. However, the total metal-ion binding capacities of single-thickness microfungal papers are limited under constant flow conditions. The total volume flowing through the system before metal-ion breakthrough occurs increases in direct proportion to the number of sheets of microfungal paper but the concomitant reduction in flow rates becomes a limiting factor. Mycelia-containing structures that allow efficient metal-ion binding at commercially acceptable flow rates are currently being investigated.

  15. Structural and optical characterization of Er-alkali-metals codoped MgO nanoparticles synthesized by solution combustion route

    Science.gov (United States)

    Sivasankari, J.; Selvakumar Sellaiyan, S.; Sankar, S.; Devi, L. Vimala; Sivaji, K.

    2017-01-01

    Pure MgO, rare-earth (Er) doped MgO (MgO:Er), and alkali metal ions (Li, Na and K) co-doped MgO:Er [i.e. MgO: Er+X (X=Li, Na, and K)] nanopowders were synthesized by solution combustion method and characterized. The XRD analysis reveals the cubic structure and the substitution of dopants and co-dopants in MgO. Annealing at 800 °C, increases the sizes of nano-crystallites of all samples appreciably, indicating the grain growth and the improvement in crystallinity of all the samples. Increase in lattice parameter, d spacing and band gap were observed after annealing. Structural and morphological analysis using scanning electron microscope (SEM) and transmission electron microscope (TEM) studies has shown that the samples contain structures like agglomerated clusters. FT-IR spectra confirm the stretching mode of hydroxyl groups, carbonate and presence of MgO bonding. The characteristic wavelength ranging from 2600 cm-1 to 3000 cm-1 were assigned to transition of 4S3/2→4I13/2 and 4I11/2→4I15/2 of Er3+.

  16. Fast ionic conduction in tetravalent metal pyrophosphate-alkali carbonate composites: New potential electrolytes for intermediate-temperature fuel cells

    Science.gov (United States)

    Singh, Bhupendra; Bhardwaj, Aman; Gautam, Sandeep K.; Kumar, Devendra; Parkash, Om; Kim, In-Ho; Song, Sun-Ju

    2017-03-01

    Here we present a report on synthesis and characterization of tetravalent metal pyrophosphate (TMP) and alkali carbonate (A2CO3; A = Li and/or Na) composites. The TMP-carbonate composites are prepared by mixing indium-doped tin pyrophosphate or yttrium-doped zirconium pyrophosphate with Li2CO3 or an eutectic mixture of Li2CO3-Na2CO3 in different wt.% ratios. The phase composition, microstructure and electrical conductivity of the sintered specimen are analyzed. In addition, the effect of different TMP and A2CO3 phases is investigated. A maximum ionic conductivity of 5.5 × 10-2 S cm-1 at 630 °C is observed in this study with a Sn0.9In0.1P2O7-Li2CO3 composite. Based on the literature data, TMP-carbonate composites can be considered to be primarily a proton and oxygen-ion co-ionic conductor and, therefore, have strong potential as electrolytes in fuel cells in 500-700 °C range.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  18. Effect of charge density in chain extension reactions involving complexes of 4, 4'-diaminodiphenylmethane and various alkali metal salts

    Science.gov (United States)

    Deshmukh, Subrajeet; Carrasquillo, Katherine; Tsai, Fang Chang; Wu, Lina; Hsu, Shaw Ling; University of Massachusetts Amherst Team

    Controlling the reaction of methylene diphenyl diisocyanate (MDI)-terminated polyester prepolymer and 4, 4'-diaminodiphenylmethane (MDA) is extremely important in many large scale applications. The ion-diamine complex has the advantage of blocking the instantaneous reaction between the diamine and isocyanate from taking place until it is released at elevated temperatures. We synthesized complexes of MDA with various alkali metal salts. These complexes create a barrier between the diamine and isocyanate thus preventing the premature reaction. We compared the complexes in terms of their dissociation and the subsequent curing with the prepolymer. Charge density had a tremendous effect. DSC showed that Na complexes dissociated at a lower temperature and needed less energy to dissociate than the Li complexes. The effect of change in cation on complex dissociation was more pronounced compared to the change in anion. Also, the ionic liquid introduced greatly altered the dissociation behavior. Temperature and time resolved IR spectroscopy was used to monitor the urea and NH band. By DSC and IR, we showed that NaCl complex is best suited for the curing of prepolymer with regards to curing temperature and energy.

  19. Alkali activation of recovered fuel-biofuel fly ash from fluidised-bed combustion: Stabilisation/solidification of heavy metals.

    Science.gov (United States)

    Yliniemi, Juho; Pesonen, Janne; Tiainen, Minna; Illikainen, Mirja

    2015-09-01

    Recovered fuel-biofuel fly ash from a fluidized bed boiler was alkali-activated and granulated with a sodium-silicate solution in order to immobilise the heavy metals it contains. The effect of blast-furnace slag and metakaolin as co-binders were studied. Leaching standard EN 12457-3 was applied to evaluate the immobilisation potential. The results showed that Ba, Pb and Zn were effectively immobilised. However, there was increased leaching after alkali activation for As, Cu, Mo, Sb and V. The co-binders had minimal or even negative effect on the immobilisation. One exception was found for Cr, in which the slag decreased leaching, and one was found for Cu, in which the slag increased leaching. A sequential leaching procedure was utilized to gain a deeper understanding of the immobilisation mechanism. By using a sequential leaching procedure it is possible fractionate elements into watersoluble, acid-soluble, easily-reduced and oxidisable fractions, yielding a total 'bioavailable' amount that is potentially hazardous for the environment. It was found that the total bioavailable amount was lower following alkali activation for all heavy metals, although the water-soluble fraction was higher for some metals. Evidence from leaching tests suggests the immobilisation mechanism was chemical retention, or trapping inside the alkali activation reaction products, rather than physical retention, adsorption or precipitation as hydroxides.

  20. First-principles study of intercalation of alkali ions in FeSe for solid-state batteries

    Science.gov (United States)

    Jiang, Zhiqiang; Gu, Xiao; Wang, Linxia; Huang, Li

    2016-08-01

    Electrochemical properties of alkali ions (Li+, Na+, and K+) intercalating into FeSe have been studied based on first-principles calculations within density functional theory. The intercalation sites of lithium ions are found to be different from sodium and potassium ions due to the small ionic radius of lithium. Calculations of minimum energy path on the diffusions of Li+, Na+, and K+ in FeSe show that the activation energies for those alkali ions increase with their ionic radii. Lithium ions have a rather smaller diffusion barrier of about 0.20 eV, which leads to a bigger diffusion coefficient of about 6.3 ×10-6cm2 /s . We also show that FeSe has a flat discharging stage at about 1.0 V with lithium ions. These results indicate that XFe2Se2 (X = Li, Na, K) may be potential electrochemical active materials, especially for solid-state electrolyte and supercapacitors.

  1. Low-Energy Grazing Ion-Scattering From Alkali-Halide Surfaces: A Novel Approach To C-14 Detection

    Science.gov (United States)

    Meyer, F. W.; Galutschek, E.; Hotchkis, M.

    2009-03-01

    Carbon-14 labeled compounds are widely used in the pharmaceutical industry, e.g., as tracers to determine the fate of these compounds in vivo. Conventional accelerator mass spectrometry (AMS) is one approach that offers sufficiently high sensitivity to avoid radiological waste and contamination issues in such studies, but requires large, expensive facilities that are usually not solely dedicated to this task. At the ORNL Multicharged Ion Research Facility (MIRF) we are exploring a small size, low cost alternative to AMS for biomedical 14C tracer studies that utilizes ECR-ion-source-generated keV-energy-range multicharged C beams grazingly incident on an alkali halide target, where efficient negative ion production by multiple electron capture takes place. By using C ion charge states of +3 or higher, the molecular isobar interference at mass 14, e.g. 12CH2 and 13CH, is eliminated. The negatively charged ions in the beam scattered from the alkali halide surface are separated from other scattered charge states by two large acceptance (˜15 msr) stages of electrostatic analysis. The N-14 isobar interference is thus removed, since N does not support a stable negative ion. Initial results for C-14 detection obtained using C-14 enriched CO2 from ANSTO will be described.

  2. Metal Ion Modeling Using Classical Mechanics.

    Science.gov (United States)

    Li, Pengfei; Merz, Kenneth M

    2017-02-08

    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems.

  3. Metal Ion Modeling Using Classical Mechanics

    Science.gov (United States)

    2017-01-01

    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems. PMID:28045509

  4. Gas and metal ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Oaks, E. [High Current Electronics Institute, Tomsk (Russian Federation)]|[State Academy of Control System and Radioelectronics, Tomsk (Russian Federation); Yushkov, G. [High Current Electronics Institute, Tomsk (Russian Federation)

    1996-08-01

    The positive ion sources are now of interest owing to both their conventional use, e.g., as injectors in charged-particle accelerators and the promising capabilities of intense ion beams in the processes related to the action of ions on various solid surfaces. For industrial use, the sources of intense ion beams and their power supplies should meet the specific requirements as follows: They should be simple, technologically effective, reliable, and relatively low-cost. Since the scanning of an intense ion beam is a complicated problem, broad ion beams hold the greatest promise. For the best use of such beams it is desirable that the ion current density be uniformly distributed over the beam cross section. The ion beam current density should be high enough for the treatment process be accomplished for an acceptable time. Thus, the ion sources used for high-current, high-dose metallurgical implantation should provide for gaining an exposure dose of {approximately} 10{sup 17} cm{sup {minus}2} in some tens of minutes. So the average ion current density at the surface under treatment should be over 10{sup {minus}5} A/cm{sup 2}. The upper limit of the current density depends on the admissible heating of the surface under treatment. The accelerating voltage of an ion source is dictated by its specific use; it seems to lie in the range from {approximately}1 kV (for the ion source used for surface sputtering) to {approximately}100 kV and over (for the ion sources used for high-current, high-dose metallurgical implantation).

  5. UV-visible spectroscopic analysis of electrical properties in alkali metal-doped amorphous zinc tin oxide thin-film transistors.

    Science.gov (United States)

    Lim, Keon-Hee; Kim, Kyongjun; Kim, Seonjo; Park, Si Yun; Kim, Hyungjun; Kim, Youn Sang

    2013-06-04

    Solution-processed and alkali metals, such as Li and Na, are introduced in doped amorphous zinc tin oxide (ZTO) semiconductor TFTs, which show better electrical performance, such as improved field effect mobility, than intrinsic amorphous ZTO semiconductor TFTs. Furthermore, by using spectroscopic UV-visible analysis we propose a comprehensive technique for monitoring the improved electrical performance induced by alkali metal doping in terms of the change in optical properties. The change in the optical bandgap supported by the Burstein-Moss theory could successfully show a mobility increase that is related to interstitial doping of alkali metal in ZTO semiconductors.

  6. Capacity-controllable nanocarriers for metal ions

    NARCIS (Netherlands)

    Yan, Y.; Keizer, de A.; Cohen Stuart, M.A.; Besseling, N.A.M.

    2009-01-01

    We report on capacity-controllable nanocarrier system for metal ions based on a novel kind of polymeric microemulsion. These microemulsions are formed in mixed systems of negatively charged metal-bisligand coordination polymers (cp), positively charged homopolyelectrolyte (hp), and positive-neutral

  7. Room temperature inorganic ``quasi-molten salts`` as alkali-metal electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, K.; Zhang, S.; Angell, C.A. [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry

    1996-11-01

    Room temperature inorganic liquids of high ionic conductivity have been prepared by reacting Lewis acid AlCl with sulfonyl chlorides. The mechanism is not clear at this time since a crystal structure study of the 1:1 complex with CH{sub 3}SO{sub 2}Cl (T{sub m} = 30 C) is not consistent with a simple chloride transfer to create AlClO{sub 4}{sup {minus}} anions. The liquid is in a state somewhere between ionic and molecular. A new term quasi-molten salt is adopted to describe this state. A comparably conducting liquid can be made using BCL{sub 3} in place of AlCl{sub 3}. Unlike their organic counterparts based on ammonium cations (e.g., pyridinium or imidazolium) which reduce in the presence of alkali metals, this inorganic class of cation shows great stability against electrochemical reduction (ca. {minus}1.0 V vs. Li{sup +}/Li), with the useful consequence that reversible lithium and sodium metal deposition/stripping can be supported. The electrochemical window for these quasi-salts with AlCl{sub 3} ranges up to 5.0 V, and their room temperature conductivities exceed 10{sup {minus}4} S/cm. They dissolve lithium and sodium tetrachloroaluminates up to mole fraction {approximately} 0.6 at 100 C and intermediate compositions are permanently stable at ambient. The resultant lithium or sodium salt solutions exhibit electrochemical windows of 4.5--5.0 V vs. Li{sup +}/Li or Na{sup +}/Na and show room temperature conductivities of 10{sup {minus}3.0}--10{sup {minus}2.5} S/cm. In preliminary charge/discharge tests, the cell Li/``quasi-ionic liquid electrolyte``/Li{sub 1+x}Mn{sub 2}O{sub 4} showed a discharge capacity of ca. 110 mAh/(g of cathode) and sustained 80% of the initial capacity after 60 cycles, indicating that these quasi-molten salt-based electrolytes are promising candidates for alkali-metal batteries.

  8. 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.

  9. 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.

  10. Bioavailability of Metal Ions and Evolutionary Adaptation

    Directory of Open Access Journals (Sweden)

    Rolando P. Hong Enriquez

    2012-10-01

    Full Text Available The evolution of life on earth has been a long process that began nearly 3,5 x 109 years ago. In their initial moments, evolution was mainly influenced by anaerobic environments; with the rise of O2 and the corresponding change in bioavailability of metal ions, new mechanisms of survival were created. Here we review the relationships between ancient atmospheric conditions, metal ion bioavailability and adaptation of metals homeostasis during early evolution. A general picture linking geochemistry, biochemistry and homeostasis is supported by the reviewed literature and is further illustrated in this report using simple database searches.

  11. Computational Design of Metal Ion Sequestering Agents

    Energy Technology Data Exchange (ETDEWEB)

    Hay, Benjamin P.; Rapko, Brian M.

    2006-06-01

    Organic ligands that exhibit a high degree of metal ion recognition are essential precursors for developing separation processes and sensors for metal ions. Since the beginning of the nuclear era, much research has focused on discovering ligands that target specific radionuclides. Members of the Group 1A and 2A cations (e.g., Cs, Sr, Ra) and the f-block metals (actinides and lanthanides) are of primary concern to DOE. Although there has been some success in identifying ligand architectures that exhibit a degree of metal ion recognition, the ability to control binding affinity and selectivity remains a significant challenge. The traditional approach for discovering such ligands has involved lengthy programs of organic synthesis and testing that, in the absence of reliable methods for screening compounds before synthesis, have resulted in much wasted research effort.

  12. Separation of metal ions in nitrate solution by ultrasonic atomization

    Science.gov (United States)

    Sato, Masanori; Ikeno, Masayuki; Fujii, Toshitaka

    2004-11-01

    In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions.

  13. The effect of alkali metals on combustion and pyrolysis of Lolium and Festuca grasses, switchgrass and willow

    Energy Technology Data Exchange (ETDEWEB)

    R. Fahmi; A.V. Bridgwater; L.I. Darvell; J.M. Jones; N. Yates; S. Thain; I.S. Donnison [Aston University, Birmingham (United Kingdom). Bio-Energy Research Group, Chemical Engineering and Applied Chemistry

    2007-07-15

    The effect of alkali metals on the thermal degradation of biomass during combustion and pyrolysis has been investigated for 19 Lolium and Festuca grass varieties. These samples have been grown under the same conditions, but has been genetically mutated to give varying lignin contents in the range 2-6% measured by Klason. These grasses also have a high alkali metal content resulting in a high ash content. In order to compare the Lolium and Festuca grasses willow chip and switchgrass were also studied to act as a reference fuels. All samples were subjected to different washing conditions to investigate the effect of decreasing the metal content. The resulting biomass samples were studied for pyrolysis characteristics using thermogravimetric analysis (TGA) and pyrolysis gas chromatography-mass spectrometry (pyroprobe-GC/MS) and for combustion characteristics by TGA. A strong catalytic effect of metals, particularly potassium, was observed in both pyrolysis and combustion. Also, it was found that as the lignin content increases, the metal content (especially potassium and sodium) decreases. Furthermore, the char yield from pyrolysis (measured at 773 K from TGA pyrolysis traces) increases as metals increase, and hence char yield increases as the lignin content decreases. Py-GCMS showed that peak intensities varied for untreated and treated samples; in particular the levoglucosan yield is higher and the hydroxyacetaldehyde yield is lower for treated (low metal content) samples. This supports previous work mechanisms by Liden et al. in which alkali metals promote an ionic route that favours ring-scission and hydroxyacetaldehyde formation. 13 refs., 10 figs., 4 tabs.

  14. Shifts in the ESR spectra of alkali-metal atoms (Li, Na, K, Rb) on helium nanodroplets.

    Science.gov (United States)

    Hauser, Andreas W; Gruber, Thomas; Filatov, Michael; Ernst, Wolfgang E

    2013-03-18

    He-droplet-induced changes of the hyperfine structure constants of alkali-metal atoms are investigated by a combination of relativistically corrected ab initio methods with a simulation of the helium density distribution based on He density functional theory. Starting from an accurate description of the variation of the hyperfine structure constant in the M-He diatomic systems (M=Li, Na, K, Rb) as a function of the interatomic distance we simulate the shifts induced by droplets of up to 10,000 (4)He atoms. All theoretical predictions for the relative shifts in the isotropic hyperfine coupling constants of the alkali-metal atoms attached to helium droplets of different size are then tied to a single, experimentally derived parameter of Rb.

  15. Ab initio quantum Monte Carlo study of the binding of a positron to alkali-metal hydrides.

    Science.gov (United States)

    Kita, Yukiumi; Maezono, Ryo; Tachikawa, Masanori; Towler, Mike D; Needs, Richard J

    2011-08-07

    Quantum Monte Carlo methods are used to investigate the binding of a positron to the alkali-metal hydrides, XH (X = Na and K). We obtain positron affinities for the NaH and KH molecules of 1.422(10) eV and 2.051(39) eV, respectively. These are considerably larger than the previous results of 1.035 eV and 1.273 eV obtained from multireference single- and double-excitation configuration interaction calculations. Together with our previous results for [LiH;e(+)] [Y. Kita et al., J. Chem. Phys. 131, 134310 (2009)], our study confirms the strong correlation between the positron affinity and dipole moment of alkali-metal hydrides.

  16. The relationship between molecular structure and biological activity of alkali metal salts of vanillic acid: Spectroscopic, theoretical and microbiological studies

    Science.gov (United States)

    Świsłocka, Renata; Piekut, Jolanta; Lewandowski, Włodzimierz

    In this paper we investigate the relationship between molecular structure of alkali metal vanillate molecules and their antimicrobial activity. To this end FT-IR, FT-Raman, UV absorption and 1H, 13C NMR spectra for lithium, sodium, potassium, rubidium and caesium vanillates in solid state were registered, assigned and analyzed. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris, Bacillus subtilis and Candida albicans. In order to evaluate the dependence between chemical structure and biological activity of alkali metal vanillates the statistical analysis was performed for selected wavenumbers from FT-IR spectra and parameters describing microbial activity of vanillates. The geometrical structures of the compounds studied were optimized and the structural characteristics were determined by density functional theory (DFT) using at B3LYP method with 6-311++G** as basis set. The obtained statistical equations show the existence of correlation between molecular structure of vanillates and their biological properties.

  17. 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.

  18. 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...

  19. 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.

  20. Collisions of alkali-metal atoms Cs and Rb in the ground state. Spin exchange cross sections

    Science.gov (United States)

    Kartoshkin, V. A.

    2016-09-01

    Collisions of alkali-metal atoms 133Cs and 85Rb in the ground state are considered in the energy interval of 10-4-10-2 au. Complex cross sections of the spin exchange, which allow one to calculate the processes of polarization transfer and the relaxation times, as well as the magnetic resonance frequency shifts caused by spin exchange Cs-Rb collisions, are obtained.

  1. Ion beam analysis of metal ion implanted surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.

  2. The Research Progress of Determination Method for Impurities in High Purity Alkali Metal Salt%高纯碱金属盐中杂质测定方法的研究进展

    Institute of Scientific and Technical Information of China (English)

    王晓辉

    2011-01-01

    高纯碱金属盐的纯度对其应用有很大影响,痕量杂质元素含量的严格控制和准确测定非常重要.本文对高纯碱金属盐中的杂质分析方法(原子吸收光谱法、分光光度法、电感耦合等离子体光谱法、电感耦合等离子体质谱法、离子色谱法等)进行了综述.%The purity of high purity alkali metal salt effects the application a lot. The strictly control and accurate determination of trace impurity is very important. The analysis methods (atomic absorption spectrometry, spectrophotometry, ICP-AES, ICP-MS, ion chromatography) for impurities in high purity alkali metal salt are summarized in this paper.

  3. An Alkali-Vapor Cell with Metal Coated Windows for Efficient Application of an Electric Field

    CERN Document Server

    Sarkisyan, D; Guena, J; Lintz, M; Bouchiat, M A; Sarkisyan, David; Gu\\'{e}na, Jocelyne; Lintz, Michel; Bouchiat, Marie-Anne

    2005-01-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2 kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no ...

  4. Alkali-vapor cell with metal coated windows for efficient application of an electric field

    Science.gov (United States)

    Sarkisyan, D.; Sarkisyan, A. S.; Guéna, J.; Lintz, M.; Bouchiat, M.-A.

    2005-05-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no magnetic part. The use of this kind of cell has resulted in an improvement of the signal-to-noise ratio in the measurement of parity violation in cesium vapor underway at ENS, Paris. The technique can be applied to other situations where a brazed assembly would give rise to unacceptably large birefringence in the windows.

  5. Faraday effect in alkali-metal vapors in a strong bichromatic field of laser light

    Science.gov (United States)

    Karagodova, T. Ya.; Kuptsova, A. V.

    2002-04-01

    Results of a numerical study of the Faraday effect arising upon propagation of the light beams with the frequencies ω L1 (resonant to the nS 1/2- nP 1/2, 3/2 transitions) and ω L2 (resonant to the nP 1/2, 3/2-( n+2) S 1/2 transitions) through alkali-metal vapors are presented. Characteristics of the magneto-optical rotation spectra at each of the frequencies are strongly affected by the second intense radiation field resonant to the adjacent transition. When the atoms interact with two strong light waves, resonant to adjacent transitions, and with a magnetic field, the shape of the Faraday rotation spectra depends on the energy shifts of the atomic states that arise due to the dynamic Stark effect and the Zeeman effect (the Paschen-Back or an intermediate-type effect), as well as due to the difference of populations of these states caused by the interaction of the atoms with the fields. The results obtained show that in the frequency selection method, based on the resonance Faraday effect, the frequency of the generated narrow-band beam can be tuned by the intensity of the strong wave, resonant to the transition between the excited states.

  6. Universal ultracold collision rates for polar molecules of two alkali-metal atoms.

    Science.gov (United States)

    Julienne, Paul S; Hanna, Thomas M; Idziaszek, Zbigniew

    2011-11-14

    Universal collision rate constants are calculated for ultracold collisions of two like bosonic or fermionic heteronuclear alkali-metal dimers involving the species Li, Na, K, Rb, or Cs. Universal collisions are those for which the short range probability of a reactive or quenching collision is unity such that a collision removes a pair of molecules from the sample. In this case, the collision rates are determined by universal quantum dynamics at very long range compared to the chemical bond length. We calculate the universal rate constants for reaction of the reactive dimers in their ground vibrational state v = 0 and for vibrational quenching of non-reactive dimers with v ≥ 1. Using the known dipole moments and estimated van der Waals coefficients of each species, we calculate electric field dependent loss rate constants for collisions of molecules tightly confined to quasi-two-dimensional geometry by a one-dimensional optical lattice. A simple scaling relation of the quasi-two-dimensional loss rate constants with dipole strength, trap frequency and collision energy is given for like bosons or like fermions. It should be possible to stabilize ultracold dimers of any of these species against destructive collisions by confining them in a lattice and orienting them with an electric field of less than 20 kV cm(-1).

  7. Exchange-correlation interaction and AO-hybridization of alkali-metal atomic clusters.

    Science.gov (United States)

    Liu, Xuan; Ito, Haruhiko; Torikai, Eiko

    2013-09-19

    The structure of alkali-metal atomic clusters is optimized with B3P86 hybrid functional for the highest spin state as well as with B3LYP hybrid functional for the lowest spin state. A dramatic change from plane to solid occurs in the highest spin state when the number of constituent atoms is four. The binding, exchange, and correlation energies are evaluated for both the highest and lowest spin states. Next, we explore the dependence of the exchange and correlation energies on the binding energy. The exchange energy contributes to the formation of the highest spin clusters, whereas the correlation energy contributes to the formation of the lowest spin clusters. The highest spin clusters are most stable when the exchange energy is a minimum. Then, to see why the ferromagnetic bond among spin-aligned identical atoms arises against Pauli exclusion principle, we estimate the mixing ratio of p orbitals in molecular orbitals. The s-p hybridization increases the binding energy in absolute value due to the extensive overlap of molecular orbitals and leads to generation of the highest spin clusters.

  8. Recent Advances In Alkali Metal Thermoelectric Converter (AMTEC) Electrode Performance And Modeling

    Science.gov (United States)

    Bankston, C. P.; Williams, R. M.; Jeffries-Nakamura, B.; Loveland, M. E.; Underwood, M. L.; Cole, T.

    1988-04-01

    The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion device, utilizing a high sodium vapor pressure or activity ratio across a beta"-alumina solid electrolyte (BASE). It has been operated at a device efficiency of 19% and at power densities near 1.0 W/cm2. This paper describes progress on the remaining scien-tific issue which must be resolved to demonstrate AMTEC feasibility for space power systems: a stable, high power density electrode. Two electrode systems have recently been discovered at JPL that now have the potential to meet space power requirements. One of these is a very thin sputtered molybdenum film, less than 0.5 micron thick, with over-lying current collection grids. This electrode has experimentally demonstrated stable performance at 0.4-0.5 W/cm2 for hundreds of hours. Recent modeling results show that at least 0.7 W/cm2 can be achieved. The model of electrode performance now includes all loss mechanisms, including charge transfer resistances at the electrode/electrolyte interface. A second electrode composition, co-sputtered platinum/tungsten, has demon-strated 0.8 W/cm2 for 160 hours. Systems studies show that a stable electrode performance of 0.6 W/cm2 will enable high efficiency (near 20%) space power systems.

  9. Quantum control of the hyperfine-coupled electron and nuclear spins in alkali-metal atoms

    Science.gov (United States)

    Merkel, Seth T.; Jessen, Poul S.; Deutsch, Ivan H.

    2008-08-01

    We study quantum control of the full hyperfine manifold in the ground-electronic state of alkali-metal atoms based on applied radio frequency and microwave fields. Such interactions should allow essentially decoherence-free dynamics and the application of techniques for robust control developed for NMR spectroscopy. We establish the conditions under which the system is controllable in the sense that one can generate an arbitrary unitary map on the system. We apply this to the case of Cs133 with its d=16 dimensional Hilbert space of magnetic sublevels in the 6S1/2 state, and design control wave forms that generate an arbitrary target state from an initial fiducial state. We develop a generalized Wigner function representation for this space consisting of the direct sum of two irreducible representations of SU(2), allowing us to visualize these states. The performance of different control scenarios is evaluated based on the ability to generate a high-fidelity operation in an allotted time with the available resources. We find good operating points commensurate with modest laboratory requirements.

  10. Silicon halide-alkali metal flames as a source of solar grade silicon

    Science.gov (United States)

    Olson, D. B.; Miller, W. J.; Gould, R. K.

    1980-01-01

    The feasibility of using continuous high-temperature reactions of alkali metals and silicon halides to produce silicon in large quantities and of suitable purity for use in the production of photovoltaic solar cells was demonstrated. Low pressure experiments were performed demonstrating the production of free silicon and providing experience with the construction of reactant vapor generators. Further experiments at higher reagent flow rates were performed in a low temperature flow tube configuration with co-axial injection of reagents and relatively pure silicon was produced. A high temperature graphite flow tube was built and continuous separation of Si from NaCl was demonstrated. A larger scaled well stirred reactor was built. Experiments were performed to investigate the compatability of graphite based reactor materials of construction with sodium. At 1100 to 1200 K none of these materials were found to be suitable. At 1700 K the graphites performed well with little damage except to coatings of pyrolytic graphite and silicon carbide which were damaged.

  11. Alkali metal salts of formazanate ligands: diverse coordination modes as a result of the nitrogen-rich [NNCNN] ligand backbone.

    Science.gov (United States)

    Travieso-Puente, Raquel; Chang, Mu-Chieh; Otten, Edwin

    2014-12-28

    Alkali metal salts of redox-active formazanate ligands were prepared, and their structures in the solid-state and in solution are determined. The nitrogen-rich [NNCNN] backbone of formazanates results in a varied coordination chemistry, with both the internal and terminal nitrogen atoms available for bonding with the alkali metal. The potassium salt K[PhNNC(p-tol)NNPh]·2THF (1-K) is dimeric in the solid state and even in THF solution, as a result of the K atom bridging via interaction with a terminal N atom and the aromatic ring of a second unit. Conversely, for the compounds Na[MesNNC(CN)NNMes]·2THF (2-Na) and Na[PhNNC((t)Bu)NNPh] (3-Na) polymeric and hexameric structures are found in the solid state respectively. The preference for binding the alkali metal through internal N atoms (1-K and 2-Na) to give a 4-membered chelate, or via internal/external N atoms (5-membered chelate in 3-Na), contrasts with the 6-membered chelate mode observed in our recently reported formazanate zinc complexes.

  12. 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.

  13. 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.

  14. [Development of trace metal ion analysis].

    Science.gov (United States)

    Kobayashi, J

    2000-09-01

    Analyses of trace biologically essential or toxic ionic compounds found in the environment are very important. However, the lack of sensitivity and interference caused by coexisting components are often serious problems. To determine trace levels of metal ions without the above problems, new preconcentration and analytical methods have been developed. Firstly, three methods for the selective preconcentration of metal ions are shown below: 1) 3-Chloropyridazine-6-carbohydrazide was immobilized on glass beads supports to be used as a column packing material. Multi-metal ions were concentrated on the column and eluted selectively with several buffers and hydrochloric acid. The eluate was analyzed off-line by flame atomized-atomic absorption spectrometry (AAS). This method was able to determine sub-ppb levels of cupper- and cadmium-ions in environmental samples. 2) Salicylideneamino-2-thiophenol was immobilized on the supports. Aluminum ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed off-line by flameless-AAS or on-line by flow injection analysis using pyrocatechol violet for a post-column colorimetric reagent. These methods were able to determine ppb-ppt levels of aluminium in environmental samples and were suitable for its state-analysis. 3) Bathocuproinesulfonic acid was immobilized on the supports. Copper ion was concentrated selectively on the column and eluted with nitric acid. The eluate was analyzed on-line by flow injection analysis using bathocuproinesulfonic acid. This method was able to determine sub-ppb levels of copper in environmental samples. On the other hand, to analyze simultaneously trace metal ions and anions, capillary electrophoresis was performed using ethylenediaminetetraacetic acid as an electrolyte component. Simultaneous determination of several ions in mineral waters was achieved by the system.

  15. Calculation of Radiative Corrections to E1 matrix elements in the Neutral Alkalis

    Energy Technology Data Exchange (ETDEWEB)

    Sapirstein, J; Cheng, K T

    2004-09-28

    Radiative corrections to E1 matrix elements for ns-np transitions in the alkali metal atoms lithium through francium are evaluated. They are found to be small for the lighter alkalis but significantly larger for the heavier alkalis, and in the case of cesium much larger than the experimental accuracy. The relation of the matrix element calculation to a recent decay rate calculation for hydrogenic ions is discussed, and application of the method to parity nonconservation in cesium is described.

  16. Metal ion sorption by untreated and chemically treated biomass

    Energy Technology Data Exchange (ETDEWEB)

    Kilbane, J.J.; Xie, J.

    1992-12-31

    The metal-binding ability of biosorbents is well known; however, in comparison with commercial ion-exchange resins the capacity of biosorbents is low. The purpose of this research was to examine chemically modified biosorbents and biosorbents prepared from microorganisms isolated from extreme environments to determine if significant improvements in metal-binding capacity or biosorbents with unique capabilities could be produced. Chemical treatments examined included acid, alkali, carbon disulfide, phosphorus oxychloride, anhydrous formamide, sodium thiosulfate, sodium chloroacetic acid, and phenylsulfonate. Biosorbents were prepared from microorganisms isolated from pristine and acid mine drainage impacted sites and included heterotrophs, methanotrophs, algae, and sulfate reducers. Chemical modification with carbon disulfide, phosphorous oxychloride, and sodium thiosulfate yielded biosorbents with such as much as 74%, 133%, and 155% improvements, respectively, in metal-binding capacity, but the performance of these chemically modified biosorbents deteriorated upon repeated use. A culture isolated from an acid mine drainage impacted site, IGTM17, exhibits about 3-fold higher metal-binding capacity in comparison with other biosorbents examined in this study. IGTM17 also exhibits superior metal-binding ability at decreased pH or in the presence of interfering common cations in comparison with other biosorbents or some commercially available cation exchange resins. Some biosorbents, such as IGTM5, can bind anions. To our knowledge this is the first demonstration of the ability of biosorbents to bind anions. Moreover, preliminary data indicate that the chemical modification of biosorbents may be capable of imparting the ability to selectively bind certain anions. Further research is needed to optimize conditions for the chemical modification and stabilization of biosorbents.

  17. Alkali-ions diffusion, mullite formation, and crystals dissolution during sintering of porcelain bodies: Microstructural approach

    DEFF Research Database (Denmark)

    Leonelli, C.; Kamseu, E.; Boccaccini, Dino

    2009-01-01

    The effect of alkali-silicate glassy matrix as replacement for feldspar in soft and hard porcelain compositions was studied. SEM and X-ray diffraction analysis were used to evidence phase evolution. For each composition, the influence of soaking time was evaluated. The difference in chemical...... composition (amount of alkali and alumina) between the two types of porcelain studied influenced the final microstructure: density, pore size and shape, and mullite content. Quartz dissolution was more important in soft porcelain where the mullitization was limited by the low amount of alumina compared...... to hard porcelain. Replacing the feldspar by alkali-silicate glassy matrices with similar chemical composition, the amount of secondary mullite and mechanical properties increased in both soft and hard compositions....

  18. Modulation of the work function of fullerenes C{sub 60} and C{sub 70} by alkali-metal adsorption: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Hong [Institute of Architecture and Engineering, Weifang University of Science and Technology, Weifang 262700 (China); Xu, Shunfu, E-mail: xushunfu2009@gmail.com [Institute of Architecture and Engineering, Weifang University of Science and Technology, Weifang 262700 (China); Department of Physics, Institute of Information Science and Engineering, Ocean University of China, Qingdao 266100 (China); Liu, Weihui [Department of Physics, Institute of Information Science and Engineering, Ocean University of China, Qingdao 266100 (China); Sun, Yueqiang; Liu, Xiangfa; Zheng, Xinqing; Li, Sen; Zhang, Qiang; Zhu, Ziliang; Zhang, Xiaochun; Dong, Chengguo [Institute of Architecture and Engineering, Weifang University of Science and Technology, Weifang 262700 (China); Li, Chun [Department of Physics, Institute of Information Science and Engineering, Ocean University of China, Qingdao 266100 (China); Yuan, Guang, E-mail: yuanguang@ouc.edu.cn [Department of Physics, Institute of Information Science and Engineering, Ocean University of China, Qingdao 266100 (China); Research Institute of Electronics, University of Shizuoka, Hamamasu 432-8011 (Japan); Mimura, Hitenori [Department of Physics, Institute of Information Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2013-11-15

    The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C{sub 60} and C{sub 70} was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C{sub 60} and C{sub 70} 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 C{sub 60} and C{sub 70}. 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 C{sub 60} and C{sub 70}.

  19. Adsorption of superfluid 4He films on planar heavy-alkali metals studied with the Orsay-Trento density functional

    Science.gov (United States)

    Szybisz, Leszek

    2003-04-01

    The wetting of planar surfaces of alkali metals (Cs, Rb, K, and Na) by superfluid 4He films at T=0 K is theoretically studied. Calculations have been carried out by using the Orsay-Trento nonlocal density functional and the adsorption potential of Chizmeshya-Cole-Zaremba. Surface tensions and contact angles are determined for several approximations. We find that the conclusion on the wetting of an Rb substrate is sensible to the gradient-gradient term in the functional and the softness of the He-metal interaction.

  20. Use of alkali metal salts to prepare high purity single-walled carbon nanotube solutions and thin films

    Science.gov (United States)

    Ashour, Rakan F.

    Single-walled carbon nanotubes (SWCNTs) display interesting electronic and optical properties desired for many advanced thin film applications, such as transparent conductive electrodes or thin-film transistors. Large-scale production of SWCNTs generally results in polydispersed mixtures of nanotube structures. Since SWCNT electronic character (conducting or semiconducting nature) depends on the nanotube structure, application performance is being held back by this inability to discretely control SWCNT synthesis. Although a number of post-production techniques are able to separate SWCNTs based on electronic character, diameter, or chirality, most still suffer from the disadvantage of high costs of materials, equipment, or labor intensity to be relevant for large-scale production. On the other hand, chromatographic separation has emerged as a method that is compatible with large scale separation of metallic and semiconducting SWCNTs. In this work, SWCNTs, in an aqueous surfactant suspension of sodium dodecyl sulfate (SDS), are separated by their electronic character using a gel chromatography process. Metallic SWCNTs (m-SWCNTs) are collected as initial fractions since they show minimum interaction with the gel medium, whereas, semiconducting SWCNTs (sc- SWCNTs) remain adsorbed to the gel. The process of sc-SWCNT retention in the gel is found to be driven by the packing density of SDS around the SWCNTs. Through a series of separation experiments, it is shown that sc-SWCNTs can be eluted from the gel simply by disturbing the configuration of the SDS/SWCNT micellar structure. This is achieved by either introducing a solution containing a co-surfactant, such as sodium cholate (SC), or solutions of alkali metal ionic salts. Analysis of SWCNT suspensions by optical absorption provides insights into the effect of changing the metal ion (M+ = Li+, Na+, and K+) in the eluting solution. Salts with smaller metal ions (e.g. Li+) require higher concentrations to achieve

  1. Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines

    Science.gov (United States)

    Shindo, F.; Zhu, C.; Kirby, K.; Babb, J. F.

    2006-01-01

    We are carrying out a joint theoretical and experimental research program to study the broadening of alkali atom resonance lines due to collisions with helium and molecular hydrogen for applications to spectroscopic studies of brown dwarfs and extrasolar giant planets.

  2. Chitosan Hydrogel Structure Modulated by Metal Ions

    Science.gov (United States)

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-10-01

    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources.

  3. Conformer of the peroxynitrite ion formed under photolysis of crystalline alkali nitrates – cis or trans?

    Science.gov (United States)

    Pak, V. Kh; Anan’ev, V. A.; Dyagileva, E. P.; Lyrshchikov, S. Yu; Miklin, M. B.; Rezvova, M. A.

    2017-01-01

    The optical and infrared reflectance spectra of the crystalline powders prepared by co-crystallization of caesium nitrate, nitrite, and peroxynitrite from alkali solution have been studied. We find that the trans conformer forms under photolysis of crystalline pure caesium nitrate. Under its dissolution the trans conformer transforms to the cis conformer.

  4. Material Removes Heavy Metal Ions From Water

    Science.gov (United States)

    Philipp, Warren H., Jr.; Street, Kenneth W.; Hill, Carol; Savino, Joseph M.

    1995-01-01

    New high capacity ion-exchange polymer material removes toxic metal cations from contaminated water. Offers several advantages. High sensitivities for such heavy metals as lead, cadmium, and copper and capable of reducing concentrations in aqueous solutions to parts-per-billion range. Removes cations even when calcium present. Material made into variety of forms, such as thin films, coatings, pellets, and fibers. As result, adapted to many applications to purify contaminated water, usually hard wherever found, whether in wastewater-treatment systems, lakes, ponds, industrial plants, or homes. Another important feature that adsorbed metals easily reclaimed by either destructive or nondestructive process. Other tests show ion-exchange polymer made inexpensively; easy to use; strong, flexible, not easily torn; and chemically stable in storage, in aqueous solutions, and in acidic or basic solution.

  5. Study on the Characteristics of an Alkali-Metal Thermoelectric Power Generation System

    Science.gov (United States)

    Lee, Wook-Hyun; Hwang, Hyun-Chang; Lee, Ji-Su; Kim, Pan-Jo; Lim, Sang-Hyuk; Rhi, Seok-Ho; Lee, Kye-Bock; Lee, Ki-Woo

    2015-10-01

    In the present study, a numerical simulation and experimental studies of an alkali-metal thermoelectric energy converter (AMTEC) system were carried out. The present, unique AMTEC model consists of an evaporator, a β-alumina solid electrolyte (BASE) tube, a condenser, and an artery cable wick. The key points for operation of the present AMTEC were 1100 K in the evaporator and 600 K in the condenser. A numerical model based on sodium-saturated porous wicks was developed and shown to be able to simulate the AMTEC system. The simulation results show that the AMTEC system can generate up to 100 W with a given design. The AMTEC system developed in the present work and used in the practical investigations could generate an electromotive force of 7 V. Artery wick and evaporator wick structures were simulated for the optimum design. Both sodium-saturated wicks were affected by numerous variables, such as the input heat power, cooling temperature, sodium mass flow rate, and capillary-driven fluid flow. Based on an effective thermal conductivity model, the presented simulation could successfully predict the system performance. Based on the numerical simulation, the AMTEC system operates with efficiency near 10% to 15%. In the case of an improved BASE design, the system could reach efficiency of over 30%. The system was designed for 0.6 V power, 25 A current, and 100 W power input. In addition, in this study, the temperature effects in each part of the AMTEC system were analyzed using a heat transfer model in porous media to apply to the computational fluid dynamics at a predetermined temperature condition for the design of a 100-W AMTEC prototype. It was found that a current density of 0.5 A/cm2 to 0.9 A/cm2 for the BASE is suitable when the temperatures of the evaporator section and condenser section are 1100 K and 600 K, respectively.

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

    Directory of Open Access Journals (Sweden)

    Liqing He

    2015-11-01

    Full Text Available Metal dodecaborates M2/nB12H12 are regarded as the dehydrogenation intermediates of metal borohydrides M(BH4n 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(BH4n. Thermal decomposition of M2B12H12 indicates multistep pathways accompanying the formation of H-deficient monomers M2B12H12−x containing the icosahedral B12 skeletons and is followed by the formation of (M2B12Hzn polymers. The decomposition behaviors are different with the in situ formed M2B12H12 during the dehydrogenation of metal borohydrides.

  7. Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

    Institute of Scientific and Technical Information of China (English)

    V.H.Rane; S.T.Chaudhari; V.R.Choudhary

    2008-01-01

    Surface properties (viz. surface area, basicity/base strength distribution, and crystal phases) of alkali metal doped CaO (alkali metal/Ca = 0.1 and 0.4) catalysts and their catalytic activity/selectivity in oxidative coupling of methane (OCM) to higher hydrocarbons at different reaction conditions (viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm3·g-1·h-1) have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties (viz. surface area, basicity/base strength distribution) and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity (strong basic sites) and the C2+ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO (Na/Ca = 0.1, before calcination) catalyst (calcined at 750 ℃), showed best performance (C2+selectivity of 68.8% with 24.7% methane conversion), whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

  8. EPR, ELDOR, and ENDOR studies of alkali metal- o-dimesitoylbenzene radical complexes in solution. II. The lithium and sodium complexes

    Science.gov (United States)

    van der Drift, E.; Smidt, J.

    A combined EPR-ELDOR-ENDOR study on ion pairs of o-dimesitoylbenzene anions with Li or Na cations provides a unique description of the alkali relaxation pattern in terms of dipolar and quadrupolar relaxation resulting from molecular tumbling. Internal motions in the chelating ring structure appear to be of minor importance. From the EPR and ELDOR results a variety of structural information is obtained: spectral densities, rotational correlation time of the complex, and anisotropic magnetic interactions of the alkali nucleus.

  9. EFFECTS OF METAL IONS ON THE CONFORMATIONAL CHANGES OF DNA

    Institute of Scientific and Technical Information of China (English)

    G. Q. Liu; Y.Y. Meng; S.H. Liu; Y.H. Hu

    2005-01-01

    DNA takes on multi-different conformations such as A-, B-, C-, D- and Z-form. These conformations can transit to one another when DNA deposited in some metal ions solutions or when changing the concentrations of the same metal ions. Here, several major conformational transitions of DNA induced by metal ions under different environment were introduced and the mechanism of the interaction of metal ions with DNA was discuss in detail.

  10. First-principles study of ternary graphite compounds cointercalated with alkali atoms (Li, Na, and K) and alkylamines towards alkali ion battery applications

    Science.gov (United States)

    Ri, Gum-Chol; Yu, Chol-Jun; Kim, Jin-Song; Hong, Song-Nam; Jong, Un-Gi; Ri, Mun-Hyok

    2016-08-01

    First-principles calculations were carried out to investigate the structural, energetic, and electronic properties of ternary graphite compounds cointercalated with alkali atoms (AM = Li, Na, and K) and normal alkylamine molecules (nCx; x = 1, 2, 3, 4), denoted as AM-nCx-GICs. From the optimization of the orthorhombic unit cells for the crystalline compounds, it was found that, with the increase in the atomic number of alkali atoms, the layer separations decrease in contrast to AM-GICs, while the bond lengths between alkali atoms and graphene layer, and nitrogen atom of alkylamine increase. The calculated formation energies and interlayer binding energies of AM-nC3-GICs indicate that the compounds is increasingly stabilized from Li to K, and the energy barriers for migration of alkali atoms suggest that alkali cation with larger ionic radius diffuses more smoothly in graphite, being similar to AM-GICs. Through the analysis of electronic properties, it was established that more extent of electronic charge is transferred from more electropositive alkali atom to the carbon ring of graphene layer, and the hybridization of valence electron orbitals between alkylamine molecules and graphene layer is occurred.

  11. Ion irradiation effects on metallic nanocrystals

    Science.gov (United States)

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C. S.; Foran, G. J.; Cookson, D. J.; Byrne, A. P.; Ridgway, M. C.

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO2. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO2 interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  12. Ohmic model for electrodeposition of metallic ions

    Energy Technology Data Exchange (ETDEWEB)

    Gliozzi, A.S. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Alexe-Ionescu, A.L. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Department of Physics, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest (Romania); Barbero, G., E-mail: giovanni.barbero@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy)

    2015-10-23

    An ohmic model to describe the electrodeposition of metallic ions on the electrodes is proposed. We assume that the ionic distribution is homogeneous across the electrolytic cell, and that the ionic current is due to the bulk electric field. The nucleation in the electrodeposition is supposed to be well described by a kinetic equation at the electrode, taking into account the neutralization of metallic ions on the electrodes. Two cases are considered. In the first case the characteristic time describing the neutralization of the ions is supposed to be negligible with respect to the flight time of the ions across the cell. In this framework the bulk electric field coincides with the external electric field, and our analysis gives analytical formulae for the surface density of deposited ions and for the electric current in the external circuit. The case where the two characteristic times are comparable, and the effective electric field in the bulk depends on the surface deposition, is considered too. In this case the ordinary differential equations describing the ionic distribution and the adsorption phenomenon have to be solved numerically. The agreement between the presented model and the experimental results published by several groups is reasonably good.

  13. Synthesis of novel calix[4]crown telomers and selective extraction of cesium ions

    Institute of Scientific and Technical Information of China (English)

    Hai Bing Li; Yuan Yin Chen; De Jun Xiong; Jun Yan Zhan; Cui Ping Han

    2007-01-01

    p-tert-Butylcalix[4]diazacrown-4 telomer, which contains hard and soft ion binding sites, was synthesized. It exhibited high selectivity toward cesium ions. The binding sites may complex alkali metal ions selectively.

  14. Identifying the presence of a disulfide linkage in peptides by the selective elimination of hydrogen disulfide from collisionally activated alkali and alkaline earth metal complexes.

    Science.gov (United States)

    Kim, Hugh I; Beauchamp, J L

    2008-01-30

    We report a new method for identifying disulfide linkages in peptides using mass spectrometry. This is accomplished by collisional activation of singly charged cationic alkali and alkaline earth metal complexes, which results in the highly selective elimination of hydrogen disulfide (H2S2). Complexes of peptides possessing disulfide bonds with sodium and alkaline earth metal are generated using electrospray ionization (ESI). Isolation followed by collision induced dissociation (CID) of singly charged peptide complexes results in selective elimination of H2S2 to leave newly formed dehydroalanine residues in the peptide. Further activation of the product yields sequence information in the region previously short circuited by the disulfide bond. For example, singly charged magnesium and calcium ion bound complexes of [Lys8]-vasopressin exhibit selective elimination of H2S2 via low-energy CID. Further isolation of the product followed by CID yields major b- and z-type fragments revealing the peptide sequence in the region between the newly formed dehydroalanine residues. Numerous model peptides provide mechanistic details for the selective elimination of H2S2. The process is initiated starting with a metal stabilized enolate anion at Cys, followed by cleavage of the S-C bond. An examination of the peptic digest of insulin provides an example of the application of the selective elimination of H2S2 for the identification of peptides with disulfide linkages. The energetics and mechanisms of H2S2 elimination from model compounds are investigated using density functional theory (DFT) calculations.

  15. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    Science.gov (United States)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

  16. 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

  17. 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.

  18. 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

    2015-12-05

    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.

  19. 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.

  20. Syntheses and Structures of Alkali Metal Rare Earth Polyphosphates CsLn(PO3)4 (Ln = La, Ce)

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; CHENG Wen-Dan; ZHANG Hao; WU Dong-Sheng; ZHAO Dan

    2008-01-01

    Alkali metal-rare earth polyphosphates, CsLn(PO3)4 (Ln = La, Ce), were synthesized by the high temperature solution reaction and studied by single-crystal X-ray diffraction technique. They crystallize in the monoclinic space group P21 (Z = 2) and feature infinite PO4 spiral chains linked with neighboring CsO10 and LnO8 polyhedra. In addition, theoretically calculated energy band structure and density of states (DOS) by the density functional theory(DFT) predict that the solid-state compound CsLa(PO3)4 possesses insulative character.

  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

    2016-09-01

    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.

  2. Metal ion levels and lymphocyte counts

    DEFF Research Database (Denmark)

    Penny, Jeannette Ø; Varmarken, Jens-Erik; Ovesen, Ole

    2013-01-01

    BACKGROUND AND PURPOSE: Wear particles from metal-on-metal arthroplasties are under suspicion for adverse effects both locally and systemically, and the DePuy ASR Hip Resurfacing System (RHA) has above-average failure rates. We compared lymphocyte counts in RHA and total hip arthroplasty (THA......) and investigated whether cobalt and chromium ions affected the lymphocyte counts. METHOD: In a randomized controlled trial, we followed 19 RHA patients and 19 THA patients. Lymphocyte subsets and chromium and cobalt ion concentrations were measured at baseline, at 8 weeks, at 6 months, and at 1 and 2 years....... RESULTS: The T-lymphocyte counts for both implant types declined over the 2-year period. This decline was statistically significant for CD3(+)CD8(+) in the THA group, with a regression coefficient of -0.04 × 10(9)cells/year (95% CI: -0.08 to -0.01). Regression analysis indicated a depressive effect...

  3. Fluorescence enhancement of photoswitchable metal ion sensors

    Science.gov (United States)

    Sylvia, Georgina; Heng, Sabrina; Abell, Andrew D.

    2016-12-01

    Spiropyran-based fluorescence sensors are an ideal target for intracellular metal ion sensing, due to their biocompatibility, red emission frequency and photo-controlled reversible analyte binding for continuous signal monitoring. However, increasing the brightness of spiropyran-based sensors would extend their sensing capability for live-cell imaging. In this work we look to enhance the fluorescence of spiropyran-based sensors, by incorporating an additional fluorophore into the sensor design. We report a 5-membered monoazacrown bearing spiropyran with metal ion specificity, modified to incorporate the pyrene fluorophore. The effect of N-indole pyrene modification on the behavior of the spiropyran molecule is explored, with absorbance and fluorescence emission characterization. This first generation sensor provides an insight into fluorescence-enhancement of spiropyran molecules.

  4. Effects of metal ion adduction on the gas-phase conformations of protein ions.

    Science.gov (United States)

    Flick, Tawnya G; Merenbloom, Samuel I; Williams, Evan R

    2013-11-01

    Changes in protein ion conformation as a result of nonspecific adduction of metal ions to the protein during electrospray ionization (ESI) from aqueous solutions were investigated using traveling wave ion mobility spectrometry (TWIMS). For all proteins examined, protein cations (and in most cases anions) with nonspecific metal ion adducts are more compact than the fully protonated (or deprotonated) ions with the same charge state. Compaction of protein cations upon nonspecific metal ion binding is most significant for intermediate charge state ions, and there is a greater reduction in collisional cross section with increasing number of metal ion adducts and increasing ion valency, consistent with an electrostatic interaction between the ions and the protein. Protein cations with the greatest number of adducted metal ions are no more compact than the lowest protonated ions formed from aqueous solutions. These results show that smaller collisional cross sections for metal-attached protein ions are not a good indicator of a specific metal-protein interaction in solution because nonspecific metal ion adduction also results in smaller gaseous protein cation cross sections. In contrast, the collisional cross section of α-lactalbumin, which specifically binds one Ca(2+), is larger for the holo-form compared with the apo-form, in agreement with solution-phase measurements. Because compaction of protein cations occurs when metal ion adduction is nonspecific, elongation of a protein cation may be a more reliable indicator that a specific metal ion-protein interaction occurs in solution.

  5. Liquid metal ion source analysis system

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, P.

    1986-06-14

    An analysis system for angular and mass resolved energy distribution measurements of liquid metal ion source beams has been constructed. The energy analyser has been calibrated, and preliminary on-axis energy distribution measurements of a gallium source operating between 0.26 and 30.0 ..mu..A have been made. These results closely agree with measurements reported by other workers, confirming the unusual FWHM behaviour of gallium sources below approx. 2 ..mu..A.

  6. 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.

  7. Metal hydrides for lithium-ion batteries.

    Science.gov (United States)

    Oumellal, Y; Rougier, A; Nazri, G A; Tarascon, J-M; Aymard, L

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH(2) with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH(2) electrode shows a large, reversible capacity of 1,480 mAh g(-1) at an average voltage of 0.5 V versus Li(+)/Li(o) which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH(2). Furthermore, the reaction is not specific to MgH(2), as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH(2), which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries.

  8. Separation of boron from borated paraffin wax by pyrohydrolysis and alkali extraction methods and its determination using ion chromatography.

    Science.gov (United States)

    Raut, Vaibhavi Vishwajeet; Jeyakumar, Subbiah; Shah, Dipti Jayesh; Thakur, Uday Kumar; Tomar, Bhupendra Singh; Ramakumar, Karanam Lakshminarayana

    2015-01-01

    A method based on the pyrohydrolysis extraction of boron and its quantification with ion chromatography was proposed for paraffin waxes borated with H3BO3 and B4C. The optimum pyrohydrolysis conditions were identified. Wax samples were mixed with U3O8, which prevents the sample from flare up, and also accelerates the extraction of boron. Pyrohydrolysis was carried out with moist O2 at 950°C for 60 and 90 min for wax with H3BO3 and wax with B4C, respectively. Two simple methods of separation based on alkali extraction and melting wax in alkali were also developed exclusively for wax with H3BO3. In all the separations, the recovery of B was above 98%. During IC separation, B was separated as boron-mannitol anion complex. Linear calibration was obtained it between 0.1 and 50 ppm of B, and LOD was calculated as 5 ppb (S/N = 3). The reproducibility was better than 5% (RSD).

  9. Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

    Energy Technology Data Exchange (ETDEWEB)

    Segal, M. J., E-mail: mattiti@gmail.com [iThemba LABS, P.O. Box 722, Somerset West 7130 (South Africa); University of Cape Town, Rondebosch, Cape Town 7700 (South Africa); Bark, R. A.; Thomae, R. [iThemba LABS, P.O. Box 722, Somerset West 7130 (South Africa); Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A. [Joint Institute for Nuclear Research, Joloit-Curie 6, 141980 Dubna, Moscow Region (Russian Federation)

    2016-02-15

    An assembly for a commercial Ga{sup +} liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga{sup +} ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga{sup +} and Au{sup +} ion beams will be reported as well.

  10. 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)

  11. 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.

  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. Influence of alkali and alkaline earth ions on the -alkylation of the lower rim phenolic-OH groups of -tert-butyl-calix[4]arene to result in amide-pendants: Template action of K+ and the structure of K+ bound tetra-amide derivative crystallized with a -tert-butylcalix[4]arene anion

    Indian Academy of Sciences (India)

    Amjad Ali; Chebrolu P Rao; Philippe Guionneau

    2008-03-01

    Role of alkali and alkaline earth ions on the formation of calix[4]arene-amide derivatives through -alkylation of the lower rim phenolic-OH groups in general and template action of K+ in particular have been explored. Na+ and K+ ions among alkali, and Ca2+ and Sr2+ ions among alkaline earth have shown tetra-amide derivatives bound to metal ion species. Among all these, potassium salts act as template and yields a K+ bound tetra-amide derivative where the charge is counter balanced by a calix[4] arene-monoanion and the product is crystallographically characterized. Change in the amide precursor used in these -alkylation reactions has no effect on the type of the amide derivative formed. Also demonstrated is a direct one-step reaction for the preparation of 1,3-di-amide derivative in high yield and low reaction period using CsHCO3.

  14. Alkali metal adsorption on Ge(0 0 1)-c(2 × 4) surface: 0.25 monolayer of Na, K, Rb and Cs

    Energy Technology Data Exchange (ETDEWEB)

    Stankiewicz, B., E-mail: bst@ifd.uni.wroc.pl [Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław (Poland); Mikołajczyk, P. [Nokia Solutions and Networks, Gen. J. Bema Str. 2, 50-265 Wrocław (Poland)

    2014-05-01

    Highlights: • We examine alkali metals adsorption on the Ge(0 0 1)-c(2 × 4) surface. • We calculated atomic and electronic structures using local-orbital and plane-waves methods. • We simulated expected scanning tunneling microscopy images. - Abstract: Alkali metals on Ge(0 0 1) surface reveal different adsorption energy depending on the initial substrate reconstruction and the adsorption site. The theoretical analysis of adsorption of 0.25 monolayer of alkali metals (Na, K, Rb and Cs) on Ge(0 0 1)-c(2 × 4) surface is presented. Stable adsorption sites are found and adsorption energy, atomic and electronic structures are given. The simulated STM images are also presented for the discussed adsorbed surface structures.

  15. Distribution and uptake of {sup 137}Cs in relation to alkali metals in a perhumid montane forest ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Chao, J.H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China)], E-mail: jhchao@mx.nthu.edu.tw; Chiu, C.Y. [Research Center for Biodiversity, Academia Sinica, Taipei 11529, Taiwan (China); Lee, H.P. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2008-10-15

    We determined the content of radiocesium ({sup 137}Cs) and alkali metals in soils, plants (2 ferns, a shrub and moss) and rainwater collected in an undisturbed forest ecosystem. The {sup 137}Cs activity and the isotopic ratio of {sup 137}Cs/Cs in the samples were used to interpret the distribution and uptake of {sup 137}Cs and the alkali metals in plants. As a whole, the {sup 137}Cs in plants was assimilated together with K but was not dependent on Cs. Different adaptations of fern species collected in ecological niches cause them to have different {sup 137}Cs/Cs ratios. Diplopterygium glaucum is distributed at the edges of the forest; it usually has shallow organic layers, and the root takes up more stable Cs from mineral layers, leading to lower {sup 137}Cs/Cs ratios than that in the understory Plagiogyria formosana and Rhododendron formosanum species. The steady supply of stable Cs through the uptake by D. glaucum from deep soils may gradually dilute the {sup 137}Cs concentration and thus explain the lower {sup 137}Cs/Cs ratio in the fern samples. The {sup 137}Cs is predicted to be proportional to the Cs content across plant species in the biological cycle once isotopic equilibrium is attained.

  16. Molecular dynamics evidence for alkali-metal rattling in the β-pyrochlores, AOs2O6 (A = K, Rb, Cs).

    Science.gov (United States)

    Shoko, E; Peterson, V K; Kearley, G J

    2013-11-27

    We have used ab initio molecular dynamics simulations validated against inelastic neutron scattering data to study alkali-metal dynamics in the β-pyrochlore osmates AOs2O6 (A=K, Rb, Cs) at 300 K to gain insight into the microscopic nature of rattling dynamics in these materials. Our results provide new evidence at the microscopic level for rattling dynamics: (1) the elemental magnitude spectra calculated from the MD show a striking dominance by the alkali metals at low energies indicating weak coupling to the cage, (2) the atomic root-mean-square displacements for the alkali metals are significantly larger than for the other atoms, e.g., 25% and 150% larger than O and Os, respectively, in KOs2O6, and (3) motions of the alkali metals are weakly correlated to the dynamics in their immediate environment, e.g. K in KOs2O6 is 6 times less sensitive to its local environment than Os, indicating weak bonding of the K. There is broadening of the elemental spectra of the alkali metals from Cs to K corresponding to a similar broadening of the local potential around these atoms as determined from potential of mean-force calculations. This feature of the spectra is partly explained by the well-known increase in the relative cage volume with decreasing atomic size of the alkali metal. We find that for the smallest rattler in this series (K) the larger relative cage volume allows this atom freedom to explore a large space inside the cage leading to vibration at a broader range of frequencies, hence a broader spectrum. Thus, since K is considered the best rattler in this series, these findings suggest that a significant feature of a good rattler is the ability to vibrate at several different but closely spaced frequencies.

  17. Rational Design of Metal Ion Sequestering Agents

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, Kenneth N.

    2000-09-30

    The discriminate bonding of metal ions is a challenge to the synthetic chemist and a phenomenon of considerable practical importance.1 An important feature of many technical applications is the specific or preferential binding of a single metal ion in the presence of many metals. Examples range from large-volume uses (e.g. ferric EDTA as a plant food, calcium complexing agents as water softeners or anticaking formulations) to very high technology applications (technetium complexation in radiopharmaceuticals, synthetic metalloenzymes). We are interested in efficient and discriminate binding of actinides for waste stream remediation. Actinides represent a major and long-lived contaminant in nuclear waste. While the separation of actinides from other radioactive components of waste, such as Sr and Cs, is relatively well established, the separation of actinides from each other and in complex solutions (e.g. those found in tank wastes) is not as well resolved. The challenge of designing metal-specific (actinide) ligands is facilitated by examples from nature. Bacteria synthesize Fe(III)-specific ligands, called siderophores, to sequester Fe(III) from the environment and return it to the cell. The similarities between Fe(III) and Pu(IV) (their charge-to-size ratios and acidity), make the siderophores prototypical for designing actinide-specific ligands. The chelating groups present in siderophores are usually hydroxamic acids and catecholamides. We have developed derivatives of these natural products which have improved properties. The catechol derivatives are the 2,3-dihydroxyterephthalamides (TAMs), and 3,4-dihydroxysulfonamides (SFAMs), and the hydroxamic acid derivatives are three isomers of hydroxypyridinones, 1,2- HOPO, 3,2-HOPO, and 3,4-HOPO. All of these ligands are attached to molecular backbones by amides and a very important feature of HOPO and CAM ligands is a strong hydrogen bonds formed between the amide proton and the adjacent phenolic oxygen in the metal

  18. Laser materials based on transition metal ions

    Science.gov (United States)

    Moncorgé, Richard

    2017-01-01

    The purpose of this presentation is to review the spectroscopic properties of the main laser materials based on transition metal ions which lead to noticeable laser performance at room temperature and, for very few cases, because of unique properties, when they are operated at cryogenic temperatures. The description also includes the materials which are currently being used as saturable absorbers for passive-Q-switching of a variety of other near- and mid-infrared solid state lasers. A substantial part of the article is devoted first to the description of the energy levels and of the absorption and emission transitions of the transition metal ions in various types of environments by using the well-known Tanabe-Sugano diagrams. It is shown in particular how these diagrams can be used along with other theoretical considerations to understand and describe the spectroscopic properties of ions sitting in crystal field environments of near-octahedral or near-tetrahedral symmetry. The second part is then dedicated to the description (positions and intensities) of the main absorption and emission features which characterize the different types of materials.

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

    Science.gov (United States)

    Soldán, Pavel; Zuchowski, Piotr S; 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.

  20. 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.

  1. 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.)

  2. 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.

  3. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

    2017-01-24

    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  4. Metal-ion solvation and abundance in atmospheric media before strong earthquakes

    Science.gov (United States)

    Lemke, K.; Aitchison, J.

    2009-12-01

    Gas phase metal-ions form hydrated complexes, which have characteristic solvation enthalpies ranging from around -150kJ/mol for monohydrates to around -40kJ/mol for larger water clusters. Previous reports on seismo-ionospheric coupling have suggested that select metal-ions M+, such as sodium and iron, are dragged by anomalous electric fields up to E-layer altitudes before earthquakes and are responsible for sporadic ionospheric metal-ion layers [Pulinets,1997 Adv.SpaceRes.,20,2173]. This report applies quantum chemical methods to calculate the geometries, energetics, thermochemistry and ionospheric abundances of a suite of solvated alkali and ionic transition metal clusters with up to six water molecules. Structural and energetic properties of ion-water clusters are calculated using Møller-Plesset perturbation theory (MP2) with a large number of different basis sets. Calculated solvation enthalpies for Na+, K+, Fe+ and Cu+ reported here are in excellent agreement with experimental mass spectrometric data. For instance, the calculated solvation enthalpy for groundstate 6D Fe+(H2O) is -108.9 kJ/mol and is in good agreement with the experimental value of -120±12 kJ/mol [Magnera,JACS,111,4100]. The subsequent hydration step toward Fe+(H2O)2, which is accompanied by a spin change to a 4A1 ground state, is exothermic by -198.0 kJ/mol. The experimental enthalpy ΔH1,2 for water attachment onto Fe+(H2O) is -170.7 [Marinelli, 1998,JACS,111,4101]. Interestingly, results from both this ab initio study and mass spectrometry demonstrate that Fe+ binds a second water molecule somewhat more strongly than the first one. The subsequent solvation steps asymptotically approach values of around -44 kJ/mol, showing a trend toward the bulk water limit. An analysis of calculated clustering equilibria K indicates that ionospheric metal ion-water cluster abundances are governed by the shifting balance between the temperature induced changes of K and water monomer abundances. Results from

  5. Metal-ion rescue revisited: biochemical detection of site-bound metal ions important for RNA folding.

    Science.gov (United States)

    Frederiksen, John K; Li, Nan-Sheng; Das, Rhiju; Herschlag, Daniel; Piccirilli, Joseph A

    2012-06-01

    Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of RNA structures. Metal-ion rescue experiments have provided a powerful approach to identify and distinguish catalytic metal ions within RNA active sites, but the ability of such experiments to identify metal ions that contribute to tertiary structure acquisition and structural stability is less developed and has been challenged. Herein, we use the well-defined P4-P6 RNA domain of the Tetrahymena group I intron to reevaluate prior evidence against the discriminatory power of metal-ion rescue experiments and to advance thermodynamic descriptions necessary for interpreting these experiments. The approach successfully identifies ligands within the RNA that occupy the inner coordination sphere of divalent metal ions and distinguishes them from ligands that occupy the outer coordination sphere. Our results underscore the importance of obtaining complete folding isotherms and establishing and evaluating thermodynamic models in order to draw conclusions from metal-ion rescue experiments. These results establish metal-ion rescue as a rigorous tool for identifying and dissecting energetically important metal-ion interactions in RNAs that are noncatalytic but critical for RNA tertiary structure.

  6. 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.

  7. Behavior of metal ions in bioelectrochemical systems: A review

    Science.gov (United States)

    Lu, Zhihao; Chang, Dingming; Ma, Jingxing; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

    2015-02-01

    Bioelectrochemical systems (BESs) have been focused on by many researchers to treat wastewater and recover energy or valuable chemicals from wastes. In BESs, metal ions play an important role in the conductivity of solution, reactors' internal resistance, power generation, chemical production and activity of microorganisms. Additionally, the metal ions are also involved in anodic or cathodic reaction processes directly or indirectly in BESs. This paper reviews the behavior of metal ions in BESs, including (1) increase of the conductivity of electrolyte and decrease of internal resistance, (2) transfer for desalination, (3) enhancement or inhibition of the biocatalysis in anode, (4) improvement of cathodic performance by metal ions through electron acceptance or catalysis in cathodic process and (5) behavior of metal ions on membranes. Moreover, the perspectives of BESs removing heavy metal ions in wastewater or solid waste are discussed to realize recovery, reduction and detoxification simultaneously.

  8. A curious interplay in the films of N-heterocyclic carbene PtII complexes upon deposition of alkali metals

    Science.gov (United States)

    Makarova, Anna A.; Grachova, Elena V.; Niedzialek, Dorota; Solomatina, Anastasia I.; Sonntag, Simon; Fedorov, Alexander V.; Vilkov, Oleg Yu.; Neudachina, Vera S.; Laubschat, Clemens; Tunik, Sergey P.; Vyalikh, Denis V.

    2016-05-01

    The recently synthesized series of PtII complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned PtII complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination PtII centre to Pt0 and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system “Pt complex-alkali metal ion” the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the PtII complexes for a variety of biomedical, sensing, chemical, and electronic applications.

  9. Temperature-Dependent Electrical Conductivity Measurements on Hydrated and Alkali-metal Intercalated Zeolite LTA and FAU

    Science.gov (United States)

    Yumoto, Kenji; Suzuki, Yoshinori; Wada, Noboru

    2007-03-01

    Zeolite LTA and FAU films were made from zeolite powders using a hydrothermal method. Electrical conductivity measurement were performed on the zeolite films in temperature range between 180 K and 430 K, using an LCR meter with the sweeping frequency varied from 20 to 1 MHz and drawing the Cole-Cole plots. The resistivities of both hydrated LTA and FAU zeolites increased with increasing the sample temperature from RT to 430 K, which might be caused by loss of water molecules from the pores of zeolite crystals. Also, the resistivities increased with decreasing the sample temperature from RT to 180 K, probably caused by freezing of water molecules in the zeolite. When the dehydrated zeolite samples were intercalated with alkali metals (Rb and K), the resistivities of the samples did not vary much at RT. However, the resistivities of the intercalated zeolite films decreased drastically by four orders of magnitude when the sample temperature was varied from RT to 180 K. We speculate that the dynamics of alkali atoms in the zeolite pores (electron-phonon scattering) may be responsible for the drastic change in the electrical conductivity.

  10. Plasma immersion ion implantation for reducing metal ion release

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J. [Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain); Leibniz-Institut fuer Oberflaechenmodifizierung, 04318 Leipzig (Germany); Universidad de Oviedo, Departamento Quimica Fisica y Analitica (Spain); Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain)

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  11. First-principles study of a double-cation alkali metal borohydride LiK(BH{sub 4}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Xiaobing; Yu Weiyang; Tang Biyu [Key Laboratory of Low Dimensional Materials and Application Technology of the Ministry of Education, Department of Physics, Xiangtan University, Hunan Province, 411105 (China)], E-mail: tangbiyu@gxu.edu.cn

    2008-11-05

    Metal borohydrides have been attracting great interest as potential candidates for use as advanced hydrogen storage materials because of their high gravimetric hydrogen densities. In the present study, first-principles calculations have been performed for the newly reported dual-cation alkali metal borohydride LiK(BH{sub 4}){sub 2}, using density functional theory (DFT) within the generalized gradient approximation and the projected augmented wave method. LiK(BH{sub 4}){sub 2} is found to have an orthorhombic structure in the space group Pnma (No 62) with nearly ideal tetrahedral shape. It is an insulating material having a DFT-calculated wide band gap of 6.08 eV. Analysis of the electronic structure shows an ionic interaction between metal cations and (BH{sub 4}){sup -} and the covalent B-H interaction within the (BH{sub 4}){sup -} tetrahedron. The enthalpy of the formation reaction from primary elements is calculated and found to be -449.8 kJ mol{sup -1}. The decomposition temperature (T{sub dec}) of LiK(BH{sub 4}){sub 2} lies between those of LiBH{sub 4} and KBH{sub 4}, which suggests that the hydrogen decomposition temperature of metal borohydrides can be precisely adjusted by the appropriate combination of cations.

  12. Experiments and Researches on Production of Highly Charged Metallic Ions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To satisfy the requirements of HIRFL (Heavy Ion Research Facility in Lanzhou), series of experiments have been done to produce metallic ion beams on the 14.5 GHz ECR ion source. By now, numerous methods have been tested, in which oven heating and MIVOC (Metallic Ion from Volatile Compounds) are both included.According to the experiments, the results show that oven heating is much better than MIVOC. In most of our

  13. 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...

  14. Effects of metal ions on recombinant calcineurin A subunit

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Effects of metal ions on activities and solution conformations of calcineurin A subunit have been examined.The ability of several metal ions to activate calcineurin A has been tested with Ni2+>Mn2+>Mg2+/Ca2+.The corresponding CD spectra and intrinsic fluorescent emission spectra show that calcineurin A exists in different metal ion-dependent conformation states.Effects of the different concentritions of Ni2+ on activities and solution conformations of calcineurin A have been tested too.Results indicate that effects of these metal ions to activate calcineurin are due to their conformational changes.

  15. 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 $\\phi^{0}_{v}$.

  16. 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

    , 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...

  17. Cation and anion dependence of stable geometries and stabilization energies of alkali metal cation complexes with FSA(-), FTA(-), and TFSA(-) anions: relationship with physicochemical properties of molten salts.

    Science.gov (United States)

    Tsuzuki, Seiji; Kubota, Keigo; Matsumoto, Hajime

    2013-12-19

    Stable geometries and stabilization energies (Eform) of the alkali metal complexes with bis(fluorosulfonyl)amide, (fluorosulfonyl)(trifluoromethylslufonyl)amide and bis(trifluoromethylsulfonyl)amide (FSA(-), FTA(-) and TFSA(-)) were studied by ab initio molecular orbital calculations. The FSA(-) complexes prefer the bidentate structures in which two oxygen atoms of two SO2 groups have contact with the metal cation. The FTA(-) and TFSA(-) complexes with Li(+) and Na(+) prefer the bidentate structures, while the FTA(-) and TFSA(-) complexes with Cs(+) prefer tridentate structures in which the metal cation has contact with two oxygen atoms of an SO2 group and one oxygen atom of another SO2 group. The two structures are nearly isoenergetic in the FTA(-) and TFSA(-) complexes with K(+) and Rb(+). The magnitude of Eform depends on the alkali metal cation significantly. The Eform calculated for the most stable TFSA(-) complexes with Li(+), Na(+), K(+), Rb(+) and Cs(+) cations at the MP2/6-311G** level are -137.2, -110.5, -101.1, -89.6, and -84.1 kcal/mol, respectively. The viscosity and ionic conductivity of the alkali TFSA molten salts have strong correlation with the magnitude of the attraction. The viscosity increases and the ionic conductivity decreases with the increase of the attraction. The melting points of the alkali TFSA and alkali BETA molten salts also have correlation with the magnitude of the Eform, which strongly suggests that the magnitude of the attraction play important roles in determining the melting points of these molten salts. The anion dependence of the Eform calculated for the complexes is small (less than 2.9 kcal/mol). This shows that the magnitude of the attraction is not the cause of the low melting points of alkali FTA molten salts compared with those of corresponding alkali TFSA molten salts. The electrostatic interactions are the major source of the attraction in the complexes. The electrostatic energies for the most stable TFSA

  18. Influence of additives on the retention of metal ions in a soil of Bangalore, India

    Directory of Open Access Journals (Sweden)

    Dr Maya Naik

    2009-04-01

    Full Text Available Liners play an important role in minimizing migration of contaminants and are frequently constructed with natural materials serving as the primary barrier to contain chemicals and potentially harmful pollutants from municipal toxic waste leachates. To improve the performance of liners, additives like lime and cement at low percentages were added to Red Soil of Bangalore. Heavy metals like hexavalent chromium, copper and zinc and alkali metals like sodium and potassium were taken as contaminants. Batch leaching tests on 50 samples were performed according to ASTM D 3987 – 85 for soil and soil mixtures with contaminants. The heavy metals were potentiometrically monitored using ion selective mercury and platinum electrodes. The alkali metals were determined using a Flame Photometry. It has been observed that the retention of heavy metals elements followed the order copper> zinc>chromium over a period of 7 to 28 days. Chromium, zinc and copper attained equilibrium in this period as confirmed based on conductivity and pH data. Cement and lime had significant effect on copper and zinc. Specific adsorption of Cu onto CaCO3 surfaces may control Cu concentration in solution. Zn adsorption increases with pH; Zinc hydrolysed at pH > 7.7 and these hydrolyzed species are strongly adsorbed to soil surfaces. Cr was retained only by 50% and additives did not have much effect as it is subjected to nonspecific adsorption (temporary. Cr was found to be highly mobile in alkaline soils. It was observed that the retention of alkali metals follows the order: K > Na. Cement and lime had positive effect on the retention of Na and K. Sodium ion retarded immediately due to the removal of exchangeable cations, whereas potassium retarded more than sodium due to the lower hydrated radius of potassium. Scanning Electron Microscopy (SEM characterization tests were performed to understand the soil mineral structure. Regular porous, sponge like, particles were detected in

  19. Hyperfine-induced quadrupole moments of alkali-metal atom ground states and their implications for atomic clocks

    CERN Document Server

    Derevianko, Andrei

    2016-01-01

    Spherically-symmetric ground states of alkali-metal atoms do not posses electric quadrupole moments. However, the hyperfine interaction between nuclear moments and atomic electrons distorts the spherical symmetry of electronic clouds and leads to non-vanishing atomic quadrupole moments. We evaluate these hyperfine-induced quadrupole moments using techniques of relativistic many-body theory and compile results for Li, Na, K, Rb, and Cs atoms. For heavy atoms we find that the hyperfine-induced quadrupole moments are strongly (two orders of magnitude) enhanced by correlation effects. We further apply the results of the calculation to microwave atomic clocks where the coupling of atomic quadrupole moments to gradients of electric fields leads to clock frequency uncertainties. We show that for $^{133}$Cs atomic clocks, the spatial gradients of electric fields must be smaller than $30 \\, \\mathrm{V}/\\mathrm{cm}^2$ to guarantee fractional inaccuracies below $10^{-16}$.

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

    Directory of Open Access Journals (Sweden)

    X. H. Liu

    2015-10-01

    Full Text Available 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X. H.; Luo, H.; Qu, T. L., E-mail: qutianliang@nudt.edu.cn; Yang, K. Y.; Ding, Z. C. [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2015-10-15

    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 {sup 87}Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the {sup 87}Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the {sup 87}Rb 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.

  2. The Trapping and Cooling of Alkalis Metal Atoms%碱金属原子的囚禁与冷却

    Institute of Scientific and Technical Information of China (English)

    邓海明; 李璋

    2012-01-01

      描述了如何利用激光以及磁场构建光学粘胶、激光阱、磁阱、磁光阱等实现对碱金属的囚禁与冷却,旨在明晰的呈现BEC实验实现的关键技术、物理原理以及各种装置的优缺点。%  This essay describes how to use laser and magnetic field to construct optical molasses ,laser trap ,mag-netic trap and magneto -optical trap to trap and cool alkali-metal atoms .It presents clearly the key experimental technologies of Bose-Einstein condensate ,the physical principle and the relative advantages and disadvantages of different equipments .

  3. One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets.

    Science.gov (United States)

    Pifrader, Alexandra; Allard, Olivier; Auböck, Gerald; Callegari, Carlo; Ernst, Wolfgang E; Huber, Robert; Ancilotto, Francesco

    2010-10-28

    Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies (≈3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n+1)p←ns transition of K, Rb, and Cs (n=4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d←5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked.

  4. 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.

  5. Development of processes for the production of solar grade silicon from halides and alkali metals, phase 1 and phase 2

    Science.gov (United States)

    Dickson, C. R.; Gould, R. K.; Felder, W.

    1981-01-01

    High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon are described. Product separation and collection processes were evaluated, measure heat release parameters for scaling purposes and effects of reactants and/or products on materials of reactor construction were determined, and preliminary engineering and economic analysis of a scaled up process were made. The feasibility of the basic process to make and collect silicon was demonstrated. The jet impaction/separation process was demonstrated to be a purification process. The rate at which gas phase species from silicon particle precursors, the time required for silane decomposition to produce particles, and the competing rate of growth of silicon seed particles injected into a decomposing silane environment were determined. The extent of silane decomposition as a function of residence time, temperature, and pressure was measured by infrared absorption spectroscopy. A simplistic model is presented to explain the growth of silicon in a decomposing silane enviroment.

  6. Conformational thermodynamics of metal-ion binding to a protein

    Science.gov (United States)

    Das, Amit; Chakrabarti, J.; Ghosh, Mahua

    2013-08-01

    Conformational changes in proteins induced by metal-ions play extremely important role in various cellular processes and technological applications. Dihedral angles are suitable conformational variables to describe microscopic conformations of a biomacromolecule. Here, we use the histograms of the dihedral angles to study the thermodynamics of conformational changes of a protein upon metal-ion binding. Our method applied to Ca2+ ion binding to an important metalloprotein, Calmodulin, reveals different thermodynamic changes in different metal-binding sites. The ligands coordinating to Ca2+ ions also play different roles in stabilizing the metal-ion coordinated protein-structure. Metal-ion binding induce remarkable thermodynamic changes in distant part of the protein via modification of secondary structural elements.

  7. Partial Oxidation of Butane to Syngas over Nickel SupportedCatalysts Modified by Alkali Metal Oxide and Rare-Earth Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The partial oxidation of butane (POB) to syngas over nickel supported catalysts was first investigated with a flow-reactor, TG and UVRRS. The NiO/g-Al2O3 is the most suitable for the POB among NiO/g-Al2O3, NiO/MgO and NiO/SiO2. And the reaction performance of the NiO/g-Al2O3 shows little difference from those of the nickel supported catalysts modified by alkali metal oxide and rare-earth metal oxide. However, modification with Li2O and La2O3 can suppress carbon-deposition of the NiO/g-Al2O3, which contains graphite-like species during the POB reaction.

  8. Metal ion binding to peptides: Oxygen or nitrogen sites?

    NARCIS (Netherlands)

    Dunbar, R. C.; Polfer, N. C.; G. Berden,; Oomens, J.

    2012-01-01

    Infrared multiple-photon dissociation (IRMPD) spectroscopy was used to probe the conformations of gas-phase metal-ion complexes between a series of five metal ions and six small peptide ligands. This report is presented in recognition and tribute for the Armentrout group's long and hugely produ

  9. Metal ion binding to peptides: oxygen or nitrogen sites?

    NARCIS (Netherlands)

    R.C. Dunbar; N.C. Polfer; G. Berden; J. Oomens

    2012-01-01

    Infrared multiple-photon dissociation (IRMPD) spectroscopy was used to probe the conformations of gas-phase metal-ion complexes between a series of five metal ions and six small peptide ligands. This report is presented in recognition and tribute for the Armentrout group's long and hugely productive

  10. In vitro cytotoxicity of metallic ions released from dental alloys

    NARCIS (Netherlands)

    Milheiro, A.; Nozaki, K.; Kleverlaan, C.J.; Muris, J.; Miura, H.; Feilzer, A.J.

    2016-01-01

    The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in c

  11. Interaction of the model alkyltrimethylammonium ions with alkali halide salts: an explicit water molecular dynamics study

    Directory of Open Access Journals (Sweden)

    M. Druchok

    2013-01-01

    Full Text Available We present an explicit water molecular dynamics simulation of dilute solutions of model alkyltrimethylammonium surfactant ions (number of methylene groups in the tail is 3, 5, 8, 10, and 12 in mixture with NaF, NaCl, NaBr, and NaI salts, respectively. The SPC/E model is used to describe water molecules. Results of the simulation at 298 K are presented in form of the radial distribution functions between nitrogen and carbon atoms of CH2 groups on the alkyltrimethylammonium ion, and the counterion species in the solution. The running coordination numbers between carbon atoms of surfactants and counterions are also calculated. We show that I- counterion exhibits the highest, and F- the lowest affinity to "bind" to the model surfactants. The results are discussed in view of the available experimental and simulation data for this and similar solutions.

  12. In situ alkali-silica reaction observed by x-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kurtis, K.E.; Monteiro, P.J.M. [Univ. of California, Berkeley, CA (United States); Brown, J.T.; Meyer-Ilse, W. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    In concrete, alkali metal ions and hydroxyl ions contributed by the cement and reactive silicates present in aggregate can participate in a destructive alkali-silica reaction (ASR). This reaction of the alkalis with the silicates produces a gel that tends to imbibe water found in the concrete pores, leading to swelling of the gel and eventual cracking of the affected concrete member. Over 104 cases of alkali-aggregate reaction in dams and spillways have been reported around the world. At present, no method exists to arrest the expansive chemical reaction which generates significant distress in the affected structures. Most existing techniques available for the examination of concrete microstructure, including ASR products, demand that samples be dried and exposed to high pressure during the observation period. These sample preparation requirements present a major disadvantage for the study of alkali-silica reaction. Given the nature of the reaction and the affect of water on its products, it is likely that the removal of water will affect the morphology, creating artifacts in the sample. The purpose of this research is to observe and characterize the alkali-silica reaction, including each of the specific reactions identified previously, in situ without introducing sample artifacts. For observation of unconditioned samples, x-ray microscopy offers an opportunity for such an examination of the alkali-silica reaction. Currently, this investigation is focusing on the effect of calcium ions on the alkali-silica reaction.

  13. [Ion specificity during ion exchange equilibrium in natural clinoptilolite].

    Science.gov (United States)

    He, Yun-Hua; Li, Hang; Liu, Xin-Min; Xiong, Hai-Ling

    2015-03-01

    Zeolites have been widely applied in soil improvement and environment protection. The study on ion specificity during ion exchange equilibrium is of important significance for better use of zeolites. The maximum adsorption capacities of alkali ions during ion exchange equilibrium in the clinoptilolite showed obvious specificity. For alkali metal ions with equivalent valence, the differences in adsorption capacity increased with the decrease of ionic concentration. These results cannot be well explained by the classical theories including coulomb force, ionic size, hydration, dispersion force, classic induction force and surface complexation. We found that the coupling of polarization effects resulted from the quantum fluctuation of diverse alkali metal ions and electric field near the zeolite surface should be the primary reason for specific ion effect during ion exchange in zeolite. The result of this coupling effect was that the difference in the ion dipole moment increased with the increase of surface potential, which further expanded the difference in the adsorption ability between zeolite surface and ions, resulting in different ion exchange adsorption ability at the solid/liquid interface. Due to the high surface charge density of zeolite, ionic size also played an important role in the distribution of ions in the double diffuse layer, which led to an interesting result that distinct differences in exchange adsorption ability of various alkali metal ions were only detected at high surface potential (the absolute value was greater than 0.2 V), which was different from the ion exchange equilibrium result on the surface with low charge density.

  14. Analysis of metal ion release from biomedical implants

    Directory of Open Access Journals (Sweden)

    Ivana Dimić

    2013-06-01

    Full Text Available Metallic biomaterials are commonly used for fixation or replacement of damaged bones in the human body due to their good combination of mechanical properties. The disadvantage of metals as implant materials is their susceptibility to corrosion and metal ion release, which can cause serious health problems. In certain concentrations metals and metal ions are toxic and their presence can cause diverse inflammatory reactions, genetic mutations or even cancer. In this paper, different approaches to metal ion release examination, from biometallic materials sample preparation to research results interpretation, will be presented. An overview of the analytical techniques, used for determination of the type and concentration of released ions from implants in simulated biofluids, is also given in the paper.

  15. DNA as sensors and imaging agents for metal ions.

    Science.gov (United States)

    Xiang, Yu; Lu, Yi

    2014-02-17

    Increasing interest in detecting metal ions in many chemical and biomedical fields has created demands for developing sensors and imaging agents for metal ions with high sensitivity and selectivity. This review covers recent progress in DNA-based sensors and imaging agents for metal ions. Through both combinatorial selection and rational design, a number of metal-ion-dependent DNAzymes and metal-ion-binding DNA structures that can selectively recognize specific metal ions have been obtained. By attachment of these DNA molecules with signal reporters such as fluorophores, chromophores, electrochemical tags, and Raman tags, a number of DNA-based sensors for both diamagnetic and paramagnetic metal ions have been developed for fluorescent, colorimetric, electrochemical, and surface Raman detection. These sensors are highly sensitive (with a detection limit down to 11 ppt) and selective (with selectivity up to millions-fold) toward specific metal ions. In addition, through further development to simplify the operation, such as the use of "dipstick tests", portable fluorometers, computer-readable disks, and widely available glucose meters, these sensors have been applied for on-site and real-time environmental monitoring and point-of-care medical diagnostics. The use of these sensors for in situ cellular imaging has also been reported. The generality of the combinatorial selection to obtain DNAzymes for almost any metal ion in any oxidation state and the ease of modification of the DNA with different signal reporters make DNA an emerging and promising class of molecules for metal-ion sensing and imaging in many fields of applications.

  16. EFFECT OF METAL IONS ON THE LACCASE ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    XiwenWang; HuaiyuZhan; WeiHe

    2004-01-01

    The effects of five metal ions(Fe-'~,Ca-~*,Mg2*,Mn-'-"Cu2") on ABTS oxidation catalyzed by laccase werestudied under condition of pH=4.5 byspectrophotometer. The results show that Fe2+ ionhas obvious effect on the activity and the nature ofinhibition is competitive type. It is found that theinhibition is realized through the reduction ofABTS.by Fe2+ ion. Other metal ions have slight influence onlaccase activity.

  17. Determination of ammonium ion in biological nitrification-denitrification process water by ion exclusion chromatography with ion exchange enhancement of conductivity detection.

    OpenAIRE

    田中, 一彦; 黒川, 利一; 中島, 良三; Fritz, James S.

    1988-01-01

    Ammonium ion in biological nitrification-denitrification process with batchwise treatment was determined by ion exclusion chromatography using water as an eluent with ion exchange enhancement of conductivity. Ammonium ion was selectively separated by ion exclusion from alkali metal and alkaline earth metal cations. The detection sensitivity of the ammonium ion was improved about 11-fold with two ion exchange enhancement columns inserted in series between the separation column packed with OH--...

  18. 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......-metal-induced reconstruction of fcc(110) surfaces are pointed out....

  19. Oxidation of cyclohexane catalyzed by metal-ion-exchanged zeolites.

    Science.gov (United States)

    Sökmen, Ilkay; Sevin, Fatma

    2003-08-01

    The ion-exchange rates and capacities of the zeolite NaY for the Cu(II), Co(II), and Pb(II) metal ions were investigated. Ion-exchange equilibria were achieved in approximately 72 h for all the metal ions. The maximum ion exchange of metal ions into the zeolite was found to be 120 mg Pb(II), 110 mg Cu(II), and 100 mg Co(II) per gram of zeolite NaY. It is observed that the exchange capacity of a zeolite varies with the exchanged metal ion and the amount of metal ions exchanged into zeolite decreases in the sequence Pb(II) > Cu(II) > Co(II). Application of the metal-ion-exchanged zeolites in oxidation of cyclohexane in liquid phase with visible light was examined and it is observed that the order of reactivity of the zeolites for the conversion of cyclohexane to cyclohexanone and cyclohexanol is CuY > CoY > PbY. It is found that conversion increases by increase of the empty active sites of a zeolite and the formation of cyclohexanol is favored initially, but the cyclohexanol is subsequently converted to cyclohexanone.

  20. 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.

  1. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Science.gov (United States)

    Aboulaich, A.; Conte, D. E.; Olivier-Fourcade, J.; Jordy, C.; Willmann, P.; Jumas, J. C.

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO 4, Li-doped BPO 4 (LiBPO) and Na-substituted BPO 4 (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li +, Na +) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO 4 matrixes (Li or Na) exhibit improved conductivity (σ RT = 2 × 10 -11 S cm -1 for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g -1 for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g -1).

  2. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Aboulaich, A.; Conte, D.E.; Olivier-Fourcade, J.; Jumas, J.C. [Institut Charles Gerhardt-Laboratoire des Agregats, Interfaces et Materiaux pour l' Energie (UMR 5253), Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Jordy, C. [SAFT, 111-113 Boulevard Alfred Daney, 33300 Bordeaux Cedex (France); Willmann, P. [Centre National d' Etudes Spatiales, 18 Avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2010-05-15

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO{sub 4}, Li-doped BPO{sub 4} (LiBPO) and Na-substituted BPO{sub 4} (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li{sup +}, Na{sup +}) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO{sub 4} matrixes (Li or Na) exhibit improved conductivity ({sigma}{sub RT} = 2 x 10{sup -11} S cm{sup -1} for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g{sup -1} for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g{sup -1}). (author)

  3. Capture of toxic radioactive and heavy metal ions from water by using titanate nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiasheng, E-mail: jiashengxu@bhu.edu.cn [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Zhang, He; Zhang, Jie [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Kim, Eui Jung [School of Chemical Engineering and Bioengineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

    2014-11-25

    Highlights: • Three types of titanate nanofibers were prepared via a hydrothermal porcess. • These nanofibers show availability for removal of the toxic ions from water. • The equilibrium data were fitted well with the Langmuir model. - Abstract: Three types of titanate nanofibers (sodium titanate nanofibers (TNF-A), potassium/sodium titanate nanofibers (TNF-B), potassium titanate nanofibers (TNF-C)) were prepared via a hydrothermal treatment of anatase powders in different alkali solutions at 170 °C for 96 h, respectively. The as-prepared nanofibers have large specific surface area and show availability for the removal of radioactive and heavy metal ions from water system, such as Ba{sup 2+} (as substitute of {sup 226}Ra{sup 2+}) and Pb{sup 2+} ions. The TNF-A shows a better capacity in the removal of Ba{sup 2+} and Pb{sup 2+} than TNF-B and TNF-C. Structural characterization of the materials was performed with powder X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and with inductively coupled plasma optical emission spectrometry (ICP-OES). It is found that the equilibrium data fit well with the Langmuir model. This study highlights that nanoparticles of inorganic ion exchangers with layered structure are potential materials for efficient removal of the toxic ions from contaminated water.

  4. Dy3+ ions doped single and mixed alkali fluoro tungsten tellurite glasses for LASER and white LED applications

    Science.gov (United States)

    Annapurna Devi, Ch. B.; Mahamuda, Sk.; Venkateswarlu, M.; Swapna, K.; Srinivasa Rao, A.; Vijaya Prakash, G.

    2016-12-01

    A new-fangled series of Dy3+ ions doped Single and Mixed Alkali Fluoro Tungsten Tellurite Glasses have been prepared by using melt quenching technique and their spectroscopic behaviour was investigated by using XRD, optical absorption, photoluminescence and lifetime measurements. The bonding parameter studies reveal the ionic nature of the Dysbnd O bond in the present glasses. From the absorption spectra, the Judd-Ofelt (J-O) intensity parameters have been determined and in turn used to determine various radiative properties for the different emission transitions from the 4F9/2 fluorescent level. The photoluminescence spectra of all the glasses exhibit two intensified peaks in blue and yellow regions corresponding to the transitions 4F9/2 → 6H15/2 (483 nm) and 4F9/2 → 6H13/2 (575 nm) respectively. From the photoluminescence spectra, it is observed that the luminescence intensity is maximum for Dy3+ ion doped potassium combination of tungsten tellurite glass (TeWK:1Dy). The highest emission cross-section and branching ratio values observed for the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions suggest the possible laser action in the visible region from these glasses. By correlating the experimental lifetimes (τexp) measured from the decay spectral features with radiative lifetimes (τR), the quantum efficiencies (η) for all the glasses have been evaluated and found to be maximum for potassium combination tungsten tellurite (TeWK:1Dy) glass. The CIE colour chromaticity coordinates (x, y), (u, v), colour correlated temperature (CCT) and Y/B ratio were also estimated from the photoluminescence spectra for different compositions of glasses. The chromaticity colour coordinates evaluated for all the glasses fall within the white light region and white light emission can be tuned by varying the composition of the glass. From all these studies, it was concluded that 1 mol% of Dy3+ ions doped TeWK glass is more suitable for lasing and white-LED applications.

  5. Preparation of Dithizone Functionalized Polystyrene for Detecting Heavy Metal Ion

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyeon Ho; Kim, Younghun [Kwangwoon University, Seoul (Korea, Republic of)

    2015-04-15

    Colorimetric sensors were usually used to detect specific metal ions using selective color change of solutions. While almost organic dye in colorimetric sensors detected single molecule, dithizone (DTZ) solution could be separately detected above 5 kinds of heavy metal ions by the change of clear color. Namely, DTZ could be used as multicolorimetric sensors. However, DTZ was generally used as aqueous type and paper/pellet-type DTZ was not reported yet. Therefore, in this work, polystyrene (PS) was prepared to composite with DTZ and then DTZ/PS pellet was obtained, which was used to selectively detect 10 kinds of heavy metal ions. When 10 ppm of Hg and Co ions was exposed in DTZ/PS pellets, clear color change was revealed. It is noted that DTZ/PS pellet could be used in detecting of heavy metal ion as dry type.

  6. Competing binding of metal ions with protein studied by microdialysis

    Institute of Scientific and Technical Information of China (English)

    GUO; Ming(郭明); KONG; Liang(孔亮); MAO; Xiqin(毛希琴); LI; Xin(历欣); ZOU; Hanfa(邹汉法)

    2002-01-01

    A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.

  7. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  8. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  9. Alkali Metal Rankine Cycle Boiler Technology Challenges and Some Potential Solutions for Space Nuclear Power and Propulsion Applications

    Science.gov (United States)

    Stone, James R.

    1994-01-01

    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. This report is aimed at evaluating alkali metal boiler

  10. Metal ion adsorption by Phomopsis sp. biomaterial in laboratory experiments and real wastewater treatments.

    Science.gov (United States)

    Saiano, Filippo; Ciofalo, Maurizio; Cacciola, Santa Olga; Ramirez, Stefania

    2005-06-01

    An insoluble material of polysaccharidic nature has been obtained by thermal alkali treatment of the filamentous fungus Phomopsis sp. FT-IR spectrum of the resulting material as well as its nitrogen content suggest that chitosan and glucans are the main components of the biomaterial. Information on Lewis base sites has also been obtained and used as a guideline in the evaluation of the complexing ability against a number of metal ions in aqueous media at pH in the range 4--6. Results indicate that after 24h contact time, up to 870 micromol/g of lead, 390 micromol/g of copper, 230 micromol/g of cadmium, 150 micromol/g of zinc and 110 micromol/g of nickel ions are adsorbed into the material. After approximately 10 min, about 70% of the overall adsorption process has already been completed. Adsorbed metal ions can be recovered by washing with dilute acid. Experiments have been extended to a real wastewater effluent confirming the potential of this biomaterial as a depolluting agent.

  11. Adsorption of rare earth metal ion by algae. Sorui ni yoru kidorui ion no kyuchaku

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, T.; Yazawa, A. (Miyagi National College of Technology, Miyagi (Japan))

    1994-02-25

    This paper reports the result of investigations on adsorption of rare earth metal ion by using algae, and adsorption of different metal ions by using egg white and soy bean protein. Rare earth metal ion is adsorbed at a considerably high rate with alga powder of different kinds. The adsorption has been judged to be cation exchange reactive adsorption, while with use of spirulina and chlorella a maximum value of adsorption rate has been observed at pH from 3 to 4.5. Therefore, selective adsorption and separation of metal ions other than rare earth metal ion has become possible. When the blue pigment extracted from spirulina, the spirulina blue, is used, the rare earth metal ion had its selective adsorption and separation performance improved higher than using spirulina itself at pH from 3 to 4.5. As a result of adsorption experiment using egg white and soy bean protein, it has been found that the metal ion adsorption behavior of the spirulina blue depends on coagulative action of protein structure to some extent. However, the sharp selective adsorption performance on rare earth metal ion due to particular pH strength has been found because of actions unique to the pigment structure of phycocyanin, a major component in the spirulina blue. 7 refs., 19 figs.

  12. The Synthesis and Characterization of Ionic Liquids for Alkali-Metal Batteries and a Novel Electrolyte for Non-Humidified Fuel Cells

    Science.gov (United States)

    Tucker, Telpriore G.

    This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy. Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl 4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC. Battery testing based on [EMI+][FeCl4 -] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br 7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4 +][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements. Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases

  13. Synthesis of Novel Metal Ion Sensors Based on DNA-Metal Interactions

    Institute of Scientific and Technical Information of China (English)

    Akira Ono; Shiqi Cao; Humika Togashi; Yoko Miyake

    2005-01-01

    @@ 1Introduction The interactions of metal ions with nucleic acids, nucleosides, and nucleo-bases have been extensively investigated[1,2]. We have reported that thymine-thymine (T-T) and cytosine-cytosine (C- C) miss base pairs in DNA duplexes highly selectively capture HgⅡ ion and Ag Ⅰ ion, which result in formations of metal-mediated base pairs, T-HgⅡ -T and C-AgⅠ -C, in duplexes[3]. The phenomenon is expected to be useful for a variety of studies such as synthesis of nano-wires containing metal ions, developing metal-ion sensing methods, etc.Here, we report novel oligodeoxyribonucleotide (ODN)-based sensors that detect HgⅡ ions and AgⅠ ions in aqueous solutions.

  14. Rechargeable dual-metal-ion batteries for advanced energy storage.

    Science.gov (United States)

    Yao, Hu-Rong; You, Ya; Yin, Ya-Xia; Wan, Li-Jun; Guo, Yu-Guo

    2016-04-14

    Energy storage devices are more important today than any time before in human history due to the increasing demand for clean and sustainable energy. Rechargeable batteries are emerging as the most efficient energy storage technology for a wide range of portable devices, grids and electronic vehicles. Future generations of batteries are required to have high gravimetric and volumetric energy, high power density, low price, long cycle life, high safety and low self-discharge properties. However, it is quite challenging to achieve the above properties simultaneously in state-of-the-art single metal ion batteries (e.g. Li-ion batteries, Na-ion batteries and Mg-ion batteries). In this contribution, hybrid-ion batteries in which various metal ions simultaneously engage to store energy are shown to provide a new perspective towards advanced energy storage: by connecting the respective advantages of different metal ion batteries they have recently attracted widespread attention due to their novel performances. The properties of hybrid-ion batteries are not simply the superposition of the performances of single ion batteries. To enable a distinct description, we only focus on dual-metal-ion batteries in this article, for which the design and the benefits are briefly discussed. We enumerate some new results about dual-metal-ion batteries and demonstrate the mechanism for improving performance based on knowledge from the literature and experiments. Although the search for hybrid-ion batteries is still at an early age, we believe that this strategy would be an excellent choice for breaking the inherent disadvantages of single ion batteries in the near future.

  15. EFFECT OF METAL IONS ON THE LACCASE ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    Xiwen Wang; Huaiyu Zhan; Wei He

    2004-01-01

    The effects of five metal ions(Fe2+、Ca2+、Mg2+、Mn2+、Cu2+) on ABTS oxidation catalyzed by laccase were studied under condition of pH=4.5 by spectrophotometer. The results show that Fe2+ ion has obvious effect on the activity and the nature of inhibition is competitive type. It is found that the inhibition is realized through the reduction ofABTS.by Fe2+ ion. Other metal ions have slight influence on laccase activity.

  16. 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.

  17. METAL ION SORPTION TO BIRCH AND SPRUCE WOOD

    Directory of Open Access Journals (Sweden)

    Pingping Su,

    2012-02-01

    Full Text Available Sorption of metal ions from aqueous solutions to birch wood and spruce heartwood and sapwood has been studied. Functional groups in wood were determined by acid-base titrations. The sorption of metal ions to wood of the different tree species was investigated by a column chromatographic technique. The mechanism of sorption is mainly ion exchange by complexation of metal ions to the functional groups, e.g. carboxyl groups and phenolic hydroxyl groups, in the wood phase. By combination of the sorption experiments with four different metal ion mixtures, the following affinity order was established for spruce sapwood particles: Fe3+>>Pb2+>>Cu2+>>Fe2+>Cd2+>Zn2+>Ni2+>Mn2+≥Ca2+≥Sr2+≥Ba2+>>Mg2+>>K+>Na+≈Li+. For all three types of stemwood studied, the affinity orders were almost the same. The ion exchange properties of wood were comparable to those of a weakly acid cation exchanger. The affinity order obtained for the synthetic resin was quite similar to the order given above for wood. The metal sorption properties of wood materials imply that they could be a potential material for removal of metal ions from aqueous solutions.

  18. 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)

  19. Designer ligands: The search for metal ion selectivity

    Directory of Open Access Journals (Sweden)

    Perry T. Kaye

    2011-03-01

    Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

  20. Metal ion removal from aqueous solution using physic seed hull.

    Science.gov (United States)

    Mohammad, Masita; Maitra, Saikat; Ahmad, Naveed; Bustam, Azmi; Sen, T K; Dutta, Binay K

    2010-07-15

    The potential of physic seed hull (PSH), Jantropha curcas L. as an adsorbent for the removal of Cd(2+) and Zn(2+) metal ions from aqueous solution has been investigated. It has been found that the amount of adsorption for both Cd(2+) and Zn(2+) increased with the increase in initial metal ions concentration, contact time, temperature, adsorbent dosage and the solution pH (in acidic range), but decreased with the increase in the particle size of the adsorbent. The adsorption process for both metal ions on PSH consists of three stages-a rapid initial adsorption followed by a period of slower uptake of metal ions and virtually no uptake at the final stage. The kinetics of metal ions adsorption on PSH followed a pseudo-second-order model. The adsorption equilibrium data were fitted in the three adsorption isotherms-Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The data best fit in the Langmuir isotherm indication monolayer chemisorption of the metal ions. The adsorption capacity of PSH for both Zn(2+) and Cd(2+) was found to be comparable with other available adsorbents. About 36-47% of the adsorbed metal could be leached out of the loaded PSH using 0.1M HCl as the eluting medium.

  1. Antimicrobial Effect of Metal Ions Substitution to HAp, Zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. J.; Kim, S. B.; Cho, S. B; Cho, K. J.; Lee, T. H. [Pai Chai University, Taejeon (Korea); Kim, T. N. [Korea Institute of Geoscience and Mineral Resources, Taejeon (Korea)

    2001-02-01

    Generally, hydroxyapatite(HAp), zeolite, carbon molecular sieve, activated carbon and alumina are used as heavy metal ions adsorption materials. Among those adsorption materials, HAp which has good positive ion-exchange ability with metal ion, and zeolite are utilized in wastewater treatment. Most of water pollutions are caused by hazardous heavy metals ions as well as bacteria in waste water. In this study, a adsorption materials (HAp and zeolite) are ion-exchanged with a well known antimicrobial metal ions, such as Ag{sup +}, Cu{sup 2+}, and Zn{sup 2+}, in order to give a adsorption of heavy metal ions and a killing effects of bacteria. The antimicrobial effects of adsorption materials are observed using by E. Coli. The results show that there is a complete antimicrobial effect in the adsorption materials with Ag{sup +} at the concentration of 1x10{sup -4}cell/ml of E. Coli until 24 hours. However, there is not good antimicrobial effects in the adsorption materials with Cu{sup 2+} and Zn{sup 2+} substitution. Feng et. al. showed the denaturation effects of silver ions which induces the condensed DNA molecules and losing their replication abilities. (author). 13 refs., 6 figs., 2 tabs.

  2. Atomic Beam Merging and Suppression of Alkali Contaminants in Multi Body High Power Targets: Design and Test of Target and Ion Source Prototypes at ISOLDE

    CERN Document Server

    Bouquerel, Elian J A; Lettry, J; Stora, T

    2009-01-01

    The next generation of high power ISOL-facilities will deliver intense and pure radioactive ion beams. Two key issues of developments mandatory for the forthcoming generation of ISOL target-ion source units are assessed and demonstrated in this thesis. The design and production of target and ion-source prototypes is described and dedicated measurements at ISOLDE-CERN of their radioisotope yields are analyzed. The purity of short lived or rare radioisotopes suffer from isobaric contaminants, notably alkalis which are highly volatile and easily ionized elements. Therefore, relying on their chemical nature, temperature controlled transfer lines were equipped with a tube of quartz that aimed at trapping these unwanted elements before they reached the ion source. The successful application yields high alkali-suppression factors for several elements (ie: 80, 82mRb, 126, 142Cs, 8Li, 46K, 25Na, 114In, 77Ga, 95, 96Sr) for quartz temperatures between 300ºC and 1100ºC. The enthalpies of adsorption on quartz were measu...

  3. Effect of semicore banding on heavy-alkali-metal lattice constants: Corrections to the frozen-core approximation

    Science.gov (United States)

    Yang, L. H.; Smith, A. P.; Benedek, R.; Koelling, D. D.

    1993-06-01

    Equilibrium lattice constants and bulk moduli of the heavy alkali metals K, Rb, and Cs were calculated using the Troullier-Martins pseudopotentials and plane-wave basis functions. The treatment of the outermost p-shell electrons as Bloch states yielded lattice constants 2-3 % larger than those obtained within the frozen-core approximation (including the partial core correction of Louie, Froyen, and Cohen [Phys. Rev. B 26, 1738 (1982)]), which narrows a long-standing discrepancy between local-density functional theory and experiment. Predicted bulk moduli are 30-50 % larger than measured values, within either treatment. The band dispersion of the semicore states (with bandwidths 0.067, 0.14, and 0.25 eV for K, Rb, and Cs) is attributed primarily to core-electron-conduction-electron hybridization rather than direct core-core overlap. The semicore density of states has a flat line shape, rather than the peaked shape expected for an idealized tight-binding band.

  4. Chemical state analysis of trace-level alkali metals sorbed in micaceous oxide by total reflection X-ray photoelectron spectroscopy

    Science.gov (United States)

    Baba, Y.; Shimoyama, I.; Hirao, N.

    2016-10-01

    In order to determine the chemical states of radioactive cesium (137Cs or 134Cs) sorbed in clay minerals, chemical states of cesium as well as the other alkali metals (sodium and rubidium) sorbed in micaceous oxides have been investigated by X-ray photoelectron spectroscopy (XPS). Since the number of atoms in radioactive cesium is extremely small, we specially focused on chemical states of trace-level alkali metals. For this purpose, we have measured XPS under X-ray total reflection (TR) condition. For cesium, it was shown that ultra-trace amount of cesium down to about 100 pg cm-2 can be detected by TR-XPS. This amount corresponds to about 200 Bq of 137Cs (t1/2 = 30.2 y). It was demonstrated that ultra-trace amount of cesium corresponding to radioactive cesium level can be measured by TR-XPS. As to the chemical states, it was found that core-level binding energy in TR-XPS for trace-level cesium shifted to lower-energy side compared with that for thicker layer. A reverse tendency is observed in sodium. Based on charge transfer within a simple point-charge model, it is concluded that chemical bond between alkali metal and micaceous oxide for ultra-thin layer is more polarized that for thick layer.

  5. 异核碱金属原子间的三体相互作用系数%Three-body dispersion coefficients for heteronuclear alkali-metal atoms

    Institute of Scientific and Technical Information of China (English)

    谢柏东; 黄时中

    2013-01-01

    By utilizing the model potential for alkali-metal atoms and the variationally stable method, the three-body dispersion coefficients for heteronuclear interactions of the alkali-metal atoms are calculated for the first time. In order to illustrate the reliability of the calculated results, the multipolar polarizabil-ities of the alkali-metal atoms are also calculated and compared with those of the previous calculations and experimental data. The results show that the present three-body dispersion coefficients are reliable.%利用碱金属原子的模型势和稳定变分法,首次计算了异核碱金属原子间的三体相互作用系数.为了说明计算结果的精度,同时计算了碱金属原子的电多级极化率.与其他作者的理论数据和有关实验数据的比较表明,本文所得到的异核碱金属原子间的三体相互作用系数是可靠的.

  6. Influence of alkali metal superoxides on structure, electronic, and optical properties of Be12O12 nanocage: Density functional theory study

    Science.gov (United States)

    Raoof Toosi, Ali; Shamlouei, Hamid Reza; Hesari, Asghar Mohammadi

    2016-09-01

    The effect of alkali metal superoxides M3O (M = Li, Na, K) on the electronic and optical properties of a Be12O12 nanocage was studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The energy gaps (Eg) of all configurations were calculated. Generally, the adsorption of alkali metal superoxides on the Be12O12 nanocage causes a decrease of Eg. Electric dipole moment μ, polarizability α, and static first hyperpolarizability β were calculated and it was shown that the adsorption of alkali metal superoxides on Be12O12 increases its polarizability. It was found that the absorption of M3O on Be12O12 nanocluster improves its nonlinear optical properties. The highest first hyperpolarizability (β ≈ 214000 a.u.) is obtained in the K3O-Be12O12 nanocluster. The TD-DFT calculations were performed to investigate the origin of the first hyperpolarizabilities and it was shown that a higher first hyperpolarizability belongs to the structure that has a lower transition energy.

  7. Experimental Study on Surface Reactions of Heavy Metal Ions With Quartz—Aqueous Ion Concentration Dependence

    Institute of Scientific and Technical Information of China (English)

    吴宏海; 吴大清; 等

    1999-01-01

    Adsorption of divalent metal ions,including Cu2+,Pb2+,Zn2+,Cd2+ and Ni2+,on quartz surface was measured as a function of metal ion concentration at 30℃under condi tions of solution pH=6.5 and ion strength I=0.1mol/L.Results of the experimental measuements can be described very well by adsorption isoterm dquations of Freudlich.The correlation coefficients(r)of adsorption isotherm lines are>0.96.Moreover,the exprimental data were interpreted on the basis of surface complexation model.Te experimental results showed that the monodentate-coordinated metal ion surface complex species(SOM+)are predominant over the bidentate-coordinated metal ion surface complex species[(SO)2M]formed only by the ions Cu2+,Zn2+ and Ni2+,And the relevant apparent surface complexation constants are lgKM=2.2-3.3 in order of KCd≥KPb>KZn>KNi≥KCu,and lgβM=5.8-6.8 in oder of βNi>βZn>βCu.Therefore,the reactive ability of the ions onto mineral surface of quartz follows the order of Cd>Pb>Zn>Ni>Cu under the above-mentioned solution conditions.The apparent surface complexation constants,influenced by the surface potential,surface species and hydrolysis of metal ions,depend mainly on the Born solvation coefficeient of the metal ions.

  8. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    KAUST Repository

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  9. THE EFFECT OF ALKALI METAL HALIDES ON THE STRUCTURE OF GLYCEROL FROM VISCOSITY B COEFFICIENT MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    A HAMMADI

    2002-12-01

    Full Text Available Viscosity B‑coefficients in glycerol obtained at 25 °C for many salts by a rearrangement in the Jones‑Dole expression are compared with those calculated applying existing theories, based on the model of hard‑charged spheres moving in a solvent continuum. Specific agreement between theory and experiment was not generally good. While the results show that Einstein’s relation can be applied to large aqueous ions, provided that the true volume‑fraction of the ions in solution can be ascertained; this expression does not lead to accurate B‑values in glycerol. For the ion‑size dependence of the B‑coefficient in aqueous solutions, Clark’s theoretical predictions agree with experiments qualitatively, in the case of glycerol, however, the model shows limitations even for small ions, for which the dielectric friction theory is expected to be applicable. Finally, all the above theories give a positive B‑coefficient, while experimental evidences showed that B could be negative.

  10. Kinetic Analysis of Metal Ions: An Undergraduate Laboratory Experiment.

    Science.gov (United States)

    Williams, Kathryn R.

    1985-01-01

    Reports on the adaptation of a kinetic method of analysis of metal ions for use in an undergraduate teaching laboratory. Background information, procedures used, and analysis of typical results obtained are provided. (JN)

  11. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Sarita Singh

    2013-01-01

    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  12. Heat transfer and flow in high-temperature alkali-metal heat pipes

    Science.gov (United States)

    Nosach, N. A.; Gontarev, Iu. K.; Prisniakov, V. F.; Iakovenko, A. G.; Kostornov, A. G.

    1982-06-01

    An experimental study of the dynamics of heat pipes with steel wool and metal fiber wicks, in particular of startup and transition from one operating mode to another, is presented. The dynamics effect of the initial heat flux in the evaporator when NaK is the working fluid is determined. The effect of interaction between the liquid and vapor phases on the heat and mass transfer from the vapor condensing on the pipe wall is analyzed.

  13. Effects of Alkali and Alkaline Earth Metals on N-Containing Species Release during Rice Straw Pyrolysis

    Directory of Open Access Journals (Sweden)

    Pan Gao

    2015-11-01

    Full Text Available To study the effects of inherent and external alkali and alkaline earth metallic species (AAEMs, i.e., K, Ca and Mg on the behavior of N-containing species release during rice straw (RS pyrolysis, different pretreatments were applied in numerous experiments. Results indicate that ammonia (NH3 and hydrogen cyanide (HCN are the major N-containing species and that the yields of isocyanic acid (HNCO and nitric oxide (NO are relatively low. The removal of inhert AAEMs shifts N-containing species release to a high-temperature zone according to volatile release behavior because of the increase in activation energy. The formation selectivity of NH3, HNCO, and NO increases by demineralized pretreatment, whereas HCN selectivity decreases. The formation of HNCO is mainly affected by alkaline earth metal. N-containing species release occurs in low temperatures with the addition of external AAEMs. The activation energy of samples impregnated with CaCl2 and MgCl2 sharply decreases compared to the original RS. The total yields of N-containing species are reduced significantly in the presence of KCl, CaCl2, and MgCl2 as additives. The inhibition ability of AAEMs follows the sequence MgCl2 > CaCl2 > KCl. The inhibition effect of MgCl2 can be improved by solution immersion compared with solid powder mixing. The clean biomass pyrolysis and gasification technology with low N-containing species content may be developed according to the results.

  14. Smart textile device using ion polymer metal compound.

    Science.gov (United States)

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

    We have developed a smart textile device that detects angular displacement of attached surface using ion polymer metal compound. The device was composed of ion polymer metal compound (IPMC) which was fabricated from Nafion resin by heat-press and chemical gold plating. The generated voltage from IPMC was measured as a function of bending angle. Fabricated IPMC device was weaved into a cotton cloth and multidirectional movements were detected.

  15. Isothermal Titration Calorimetry Measurements of Metal Ions Binding to Proteins.

    Science.gov (United States)

    Quinn, Colette F; Carpenter, Margaret C; Croteau, Molly L; Wilcox, Dean E

    2016-01-01

    ITC measurements involving metal ions are susceptible to a number of competing reactions (oxidation, precipitation, and hydrolysis) and coupled reactions involving the buffer and protons. Stabilization and delivery of the metal ion as a well-defined and well-characterized complex with the buffer, or a specific ligand, can suppress undesired solution chemistry and, depending on the stability of the metal complex, allow accurate measurements of higher affinity protein-binding sites. This requires, however, knowledge of the thermodynamics of formation of the metal complex and accounting for its contribution to the experimentally measured values (KITC and ΔHITC) through a post hoc analysis that provides the condition-independent binding thermodynamics (K, ΔG(o), ΔH, ΔS, and ΔCP). This analysis also quantifies the number of protons that are displaced when the metal ion binds to the protein.

  16. Erosion yield of metal surface under ion pulsed irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Krivobokov, Valery; Stepanova, Olga, E-mail: omsa@tpu.ru; Yuryeva, Alena

    2013-11-15

    The paper is devoted to the study of erosion processes on a metal surface (Ag, Ni, Cu, W) under argon ion bombardment. The erosion yields including the sputtered and evaporated particles have been calculated for a wide range of the initial ion energy (1–1000 keV). They are revealed to reach the values from units to 10{sup 4} atom/ion under a pulsed ion beam with the power density of 10{sup 2}–10{sup 10} W/cm{sup 2}. The ion beam and target parameters are shown to influence on the erosion intensity.

  17. Conditions for preparation of ultrapure beryllium by electrolytic refining in molten alkali-metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Wohlfarth, Hagen

    1982-02-01

    Electrolytic refining is regarded as the most suitable process for the production of beryllium with impurity contents below 1 at.-ppM. Several parameters are important for electrolytic refining of beryllium in a BeCl/sub 2/-containing LiCl-KCl melt: current density, BeCl/sub 2/ content, electrolyte temperature, composition of the unpurified beryllium and impurity-ion concentrations in the melt, as well as apparatus characteristics such as rotation speed of the cathode and condition of the crucible material. These factors were studied and optimized such that extensive removal of the maximum number of accompanying and alloying elements was achieved.

  18. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

    Directory of Open Access Journals (Sweden)

    Qingqing Wang

    2014-09-01

    Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

  19. Functional identification of catalytic metal ion binding sites within RNA.

    Directory of Open Access Journals (Sweden)

    James L Hougland

    2005-09-01

    Full Text Available The viability of living systems depends inextricably on enzymes that catalyze phosphoryl transfer reactions. For many enzymes in this class, including several ribozymes, divalent metal ions serve as obligate cofactors. Understanding how metal ions mediate catalysis requires elucidation of metal ion interactions with both the enzyme and the substrate(s. In the Tetrahymena group I intron, previous work using atomic mutagenesis and quantitative analysis of metal ion rescue behavior identified three metal ions (MA, MB, and MC that make five interactions with the ribozyme substrates in the reaction's transition state. Here, we combine substrate atomic mutagenesis with site-specific phosphorothioate substitutions in the ribozyme backbone to develop a powerful, general strategy for defining the ligands of catalytic metal ions within RNA. In applying this strategy to the Tetrahymena group I intron, we have identified the pro-SP phosphoryl oxygen at nucleotide C262 as a ribozyme ligand for MC. Our findings establish a direct connection between the ribozyme core and the functionally defined model of the chemical transition state, thereby extending the known set of transition-state interactions and providing information critical for the application of the recent group I intron crystallographic structures to the understanding of catalysis.

  20. 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.

  1. Desorption Dynamics of Heavy Alkali Metal Atoms (Rb, Cs) off the Surface of Helium Nanodroplets

    CERN Document Server

    von Vangerow, J; Stienkemeier, F; Mudrich, M; Leal, A; Mateo, D; Hernando, A; Barranco, M; Pi, M

    2014-01-01

    We present a combined ion imaging and density functional theory study of the dynamics of the desorption process of rubidium and cesium atoms off the surface of helium nanodroplets upon excitation of the perturbed $6s$ and $7s$ states, respectively. Both experimental and theoretical results are well represented by the pseudodiatomic model for effective masses of the helium droplet in the desorption reaction of m_eff/m_He~10 (Rb) and 13 (Cs). Deviations from this model are found for Rb excited to the 6p state. Photoelectron spectra indicate that the dopant-droplet interaction induces relaxation into low-lying electronic states of the desorbed atoms in the course of the ejection process.

  2. Desorption dynamics of heavy alkali metal atoms (Rb, Cs) off the surface of helium nanodroplets.

    Science.gov (United States)

    von Vangerow, J; Sieg, A; Stienkemeier, F; Mudrich, M; Leal, A; Mateo, D; Hernando, A; Barranco, M; Pi, M

    2014-08-21

    We present a combined ion imaging and density functional theory study of the dynamics of the desorption process of rubidium and cesium atoms off the surface of helium nanodroplets upon excitation of the perturbed 6s and 7s states, respectively. Both experimental and theoretical results are well represented by the pseudodiatomic model for effective masses of the helium droplet in the desorption reaction of meff/mHe ≈ 10 (Rb) and 13 (Cs). Deviations from this model are found for Rb excited to the 6p state. Photoelectron spectra indicate that the dopant-droplet interaction induces relaxation into low-lying electronic states of the desorbed atoms in the course of the ejection process.

  3. Inelastic neutron scattering spectra of alkali metal (Na, K) bifluorides: The harmonic overtone of v3

    Science.gov (United States)

    Waddington, Thomas C.; Howard, Joseph; Brierley (in part), Keith P.; Tomkinson, John

    1982-01-01

    Inelastic neutron scattering spectra of MFHF (M  Na and K) have been measured up to energy transfers of ca. 4000 cm -1 Both 0 → 1 and 0 → 2 transitions of the bending ( v2), and antisymmetric stretching ( v3) modes were observed. A normal harmonic (i.e. no quartic contribution) model for the dynamics of the bifluoride ion is entirely consistent with our observations. Evidence of phonon dispersion was observed in the band shape of v3, but no structure attributable to the LO mode could be found. The similarity of the band shapes of v3 for both NaFHF and KFHF is interpreted in terms of a very short range coupling mechanism.

  4. Metal ion trend may be more predictive for malfunctioning metal-on-metal implants than a single measurement

    NARCIS (Netherlands)

    Smolders, J.M.; Hol, A.; Susante, J.L.C. van

    2013-01-01

    Forty-eight unilateral hip resurfacing arthroplasty patients were evaluated for cobalt and chromium levels. The metal ion trend of 42 well-functioning patients was compared with six sub-optimal functioning patients. Median metal ion levels were significantly higher for the sub-optimal group. For the

  5. Conditioning of spent ion-exchange resins followed by solidification in the alkali-slag long-lived matrix with an increased level of filling with resins

    Directory of Open Access Journals (Sweden)

    Svetlana Nikolaevna Skomorokhova

    2015-12-01

    Full Text Available The possibility for spent ion-exchange resins (IER of intermediate specific activity to be solidified in alkali-slag (geocement water-resistant matrixes with an increased level of filling with resins was studied. Comparative tests of the IER immobilization process were done for justifying the most technologically effective matrix material. We used three different alkali-slag cementing systems and the prepared simulated pulps of IER with the specific activity of 3×108 Bq/L, saturated with 137Cs radionuclide. The manufactured samples of the alkali-slag compounds, filled with IER at the level of 24-27% by weight, meet the regulatory requirements set in NP-019-15 code and feature better working quality parameters (mechanical strength: 5-14 MPa, leaching rate of 137Cs, Na, Ca: <2×10-4 g/cm2∙day on the 7th-10th day, mechanical strength of compounds rises by the factor of 1.2-1.5 after immersion tests. The incorporation of the spent IER in the most technologically effective alkali-slag matrix makes it possible to decrease the cementing material consumption by the factor of 2.4 in comparison with Portland cement and by the factor of 1.3 in comparison with the known slag binders, while a compound with better quality parameters is produced. The research was done with the support of the Russian Ministry of Education and Science (unique identifier of the applied research studies - RFMEFI57915X0101 for justifying a new energy-efficient and resource-saving technology of reprocessing the spent IER-containing waste.

  6. 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

  7. Anionic Gallium-Based Metal;#8722;Organic Framework and Its Sorption and Ion-Exchange Properties

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Debasis; Kim, Sun Jin; Wu, Haohan; Xu, Wenqian; Borkowski, Lauren A.; Li, Jing; Parise, John B. (Kwangju); (Rutgers); (SBU)

    2012-04-30

    A gallium-based metal-organic framework Ga{sub 6}(C{sub 9}H{sub 3}O{sub 6}){sub 8} {center_dot} (C{sub 2}H{sub 8}N){sub 6}(C{sub 3}H{sub 7}NO){sub 3}(H{sub 2}O){sub 26} [1, Ga{sub 6}(1,3,5-BTC){sub 8} {center_dot} 6DMA {center_dot} 3DMF {center_dot} 26H{sub 2}O], GaMOF-1; BTC = benzenetricarboxylate/trimesic acid and DMA = dimethylamine, with space group I{bar 4}3d, a = 19.611(1) {angstrom}, and V = 7953.4(6) {angstrom}{sup 3}, was synthesized using solvothermal techniques and characterized by synchrotron-based X-ray microcrystal diffraction. Compound 1 contains isolated gallium tetrahedra connected by the organic linker (BTC) forming a 3,4-connected anionic porous network. Disordered positively charged ions and solvent molecules are present in the pore, compensating for the negative charge of the framework. These positively charged molecules could be exchanged with alkali-metal ions, as is evident by an ICP-MS study. The H{sub 2} storage capacity of the parent framework is moderate with a H{sub 2} storage capacity of {approx}0.5 wt % at 77 K and 1 atm.

  8. In Vivo Metal Ion Imaging Using Fluorescent Sensors.

    Science.gov (United States)

    Van de Bittner, Genevieve C; Hirayama, Tasuku

    2016-01-01

    In vivo imaging in living animals provides the ability to monitor alterations of signaling molecules, ions, and other biological components during various life stages and in disease. The data gained from in vivo imaging can be used for biological discovery or to determine elements of disease progression and can inform the development and translation of therapeutics. Herein, we present theories behind small-molecule, fluorescent, metal ion sensors as well as the methods for their successful application to in vivo metal ion imaging, including ex vivo validation.

  9. Complex formation during dissolution of metal oxides in molten alkali carbonates

    DEFF Research Database (Denmark)

    Li, Qingfeng; Borup, Flemming; Petrushina, Irina;

    1999-01-01

    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...

  10. 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.

  11. THE THEORETICAL STUDY OF ADSORPTION OF METAL IONS ON CHITOSAN

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency analysis of all cluster models have been performed employing B3LYP hybrid method at 3-21G basis set level except metal ions which were invoked to use effective core potential (ECP) method. The energy changes, and the main structural parameters have been obtained during the theoretical study of the adsorption of metal ions on the chitosan. The calculations showed that the coordination modes of metal ions with chitosan models were different, the geometries of Mn2+, Zn2+, Cd2+, Hg2+, Pb2+ ions coordinated with two nitrogen atoms and two oxygen atoms were distorted tetrahedral, while the square planar structure of Ni2+ coordinated two nitrogen atoms and two oxygen atoms was observed. The heat of reaction between six metal ions and chitosan models showed the order: Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+, this suggested that the coordination strength of Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+.

  12. Hall transport of divalent metal ion modified DNA lattices

    Energy Technology Data Exchange (ETDEWEB)

    Dugasani, Sreekantha Reddy; Lee, Keun Woo; Yoo, Sanghyun; Gnapareddy, Bramaramba; Bashar, Saima; Park, Sung Ha, E-mail: sunghapark@skku.edu [Department of Physics and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Si Joon; Jung, Joohye; Jung, Tae Soo; Kim, Hyun Jae, E-mail: hjk3@yonsei.ac.kr [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2015-06-29

    We investigate the Hall transport characteristics of double-crossover divalent metal ion (Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+})-modified DNA (M-DNA) lattices grown on silica via substrate-assisted growth. The electronic characteristics of the M-DNA lattices are investigated by varying the concentration of the metal ions and then conducting Hall measurements, including resistivity, Hall mobility, carrier concentration, and magneto resistance. The tendency of the resistivity and Hall mobility was to initially decrease as the ion concentration increased, until reaching the saturation concentration (C{sub s}) of each metal ion, and then to increase as the ion concentration increased further. On the other hand, the carrier concentration revealed the opposite tendency as the resistivity and Hall mobility. The specific binding (≤C{sub s}) and the nonspecific aggregates (>C{sub s}) of the ions into the DNA lattices were significantly affected by the Hall characteristics. The numerical ranges of the Hall parameters revealed that the M-DNA lattices with metal ions had semiconductor-like characteristics. Consequently, the distinct characteristics of the electrical transport through M-DNA lattices will provide useful information on the practical use of such structures in physical devices and chemical sensors.

  13. A vacuum spark ion source: High charge state metal ion beams

    Science.gov (United States)

    Yushkov, G. Yu.; Nikolaev, A. G.; Oks, E. M.; Frolova, V. P.

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  14. A vacuum spark ion source: High charge state metal ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Oks, E. M. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Science, Tomsk 634055 (Russian Federation); Tomsk State University of Control System and Radioelectronics, Tomsk 634050 (Russian Federation)

    2016-02-15

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  15. Synthesis and Characteristics of A Novel Heavy Metal Ions Chelator

    Institute of Scientific and Technical Information of China (English)

    LIU Zhuannian; SONG Yejing; HAN Xiaogang

    2012-01-01

    Polyacrylamide-urea-sulfanilamide(PUS) was prepared as a novel heavy metal ions chelator and successfully used to simultaneously remove heavy metals from wastewater effluents.The effects of reaction parameters (sodium hydroxide,material ratio,temprature and contact time) were monitored to specify the best synthesis conditions.PUS was chemically characterized by means of infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis).The simultaneous chelation performance of PUS towards selected heavy metals ions,Ni2+,Cu2+,Pb2+,Zn2+,Cd2+ was discussed,showing that Ni2+,Cu2+,Pb2+,Zn2+ could be better chelated.It is indicated that the synthesized PUS is a potential remediation material when used for the treatment of wastewater containing metal ions.

  16. 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...... mu(2)-bridging by the fluoride ligands in a linear fashion between Na+-ions and chromium centres in catena-[Na(H2O)(4)(mu-F)-trans-{CrF(py)(4))](HCO3)(2) and in the dimers [Li(H2O)(n)(mu-F)-trans-{CrF(py)(4))}](2+) (n = 3, 4). The uncharged chromium complexes fac-[CrF3(Me(3)tacn)] and mer-[CrF3(terpy......)] 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...

  17. Low temperature alkali metal-sulfur batteries. Final report, December 1, 1974-November 30, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Brummer, S.B.; Rauh, R.D.; Abraham, K.M.; Dampier, F.W.; Subrahmanyam, V.; Pearson, G.F.; Surprenant, J.K.; Buzby, J.M.

    1980-03-01

    Work on the development of rechargeable, ambient-temperature Li/sulfur and Li/metal sulfide batteries is reported. The Li/S system has the cathode material dissolved in the electrolyte, as Li/sub 2/S/sub n/. Tetrahydrofuran, 1M LiAsF/sub 6/, is one of the more attractive electrolytes discovered for this cell, since it can dissolve up to approx. 10M S as Li/sub 2/Sn. Despite the oxidative nature of the electrolyte, Li is stable in it and can be electrodeposited from it on battery charge. Cells of the configuration Li 5M S (as Li/sub 2/S/sub n/), THF, 1M LiAsF/sub 6//carbon can be discharged at 50/sup 0/C with a utilization of nearly 1.5e/sup -//S at the C/3 rate. This corresponds to the rate-capacity goal for this battery in its proposed vehicular or load-leveling applications. Further improvements in rate are possible. Rechargeability of 135 cycles of 0.1 e/sup -//S and approx. 45 cycles of 0.5 e/sup -//S was demonstrated. The self-discharge reaction keeps the Li electrode free of electrically isolated dendrites. Ultimate failure on cycling is due to cathode depletion via precipitation of Li/sub 2/S on the anode in a form insoluble in the electrolyte. Attempts to solubilize the Li/sub 2/S by the internal generation of an oxidizing scavenger (e.g., Br/sub 2/) or by addition of Lewis acids have met only with limited success. Cells of configuration Li/THF, 1M LiAsF/sub 6//insoluble metal sulfide were investigated, using the following cathodes: CuS, NiS, SiS/sub 2/, MnS/sub 2/, FeS, and Bi/sub 2/S/sub 3/. Of these, the most promising new material in terms of energy density and rechargeability is CuS. Well over 100 cycles for Li/CuS cells with moderate cathode loadings were demonstrated. CuS compares favorably with TiS/sub 2/ in terms of energy density and rechargeability and is superior in terms of economics. 39 figures, 19 tables.

  18. Complexation-induced supramolecular assembly drives metal-ion extraction.

    Science.gov (United States)

    Ellis, Ross J; Meridiano, Yannick; Muller, Julie; Berthon, Laurence; Guilbaud, Philippe; Zorz, Nicole; Antonio, Mark R; Demars, Thomas; Zemb, Thomas

    2014-09-26

    Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts.

  19. 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.

  20. Therapeutic redistribution of metal ions to treat Alzheimer's disease.

    Science.gov (United States)

    Crouch, Peter J; Barnham, Kevin J

    2012-09-18

    Currently, therapeutics that modify Alzheimer's disease (AD)are not available. Increasing age is the primary risk factor for AD and due to an aging global population the urgent need for effective therapeutics increases every year. This Account presents the development of an AD treatment strategy that incorporates diverse compounds with a common characteristic: the ability to redistribute metal ions within the brain. Central to cognitive decline in AD is the amyloid-β peptide (Aβ) that accumulates in the AD brain. A range of therapeutic strategies have been developed based on the premise that decreasing the brain Aβ burden will attenuate the severity of the disease symptoms. Unfortunately these treatments have failed to show any positive outcomes in large-scale clinical trials, raising many questions regarding whether therapeutics for AD can rely solely on decreasing Aβ levels. An alternate strategy is to target the interaction between Aβ and metal ions using compounds with the potential to redistribute metal ions within the brain. The original rationale for this strategy came from studies showing that metal ions promote Aβ toxicity and aggregation. In initial studies using the prototype metal-chelating compound clioquinol (CQ), CQ prevented Aβ toxicity in vitro, out-competed Aβ for metal ions without affecting the activity of metal-dependent enzymes, and attenuated the rate of cognitive decline in AD subjects in a small phase II clinical trial. All these outcomes were consistent with the original hypothesized mechanism of action for CQ where prevention or reversal of the extracellular Aβ-metal interactions could prevent Aβ toxicity. Soon after the completion of these studies, a new body of work began to suggest that this hypothesized mechanism of action for CQ was simplistic and that other factors were also important for the positive therapeutic outcomes. Perhaps most significantly, it was shown that after CQ sequesters metal ions the neutral CQ-metal

  1. Auger neutralization rates of multiply charged ions near metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nedeljkovic, N.N.; Janev, R.K.; Lazur, V.Y.

    1988-08-15

    Transition rates for the Auger neutralization processes of multiply charged ions on metal surfaces are calculated in closed analytical form. The core potential of a multiply charged ion is represented by a pseudopotential, which accounts for the electron screening effects and allows transition to the pure Coulomb case (fully stripped ions). The relative importance of various neutralization channels in slow-ion--surface collisions is discussed for the examples of He/sup 2+/+Mo(100) and C/sup 3+/+Mo(100) collisional systems.

  2. Metal ions potentiate microglia responsiveness to endotoxin.

    Science.gov (United States)

    Rachmawati, Dessy; Peferoen, Laura A N; Vogel, Daphne Y S; Alsalem, Inás W A; Amor, Sandra; Bontkes, Hetty J; von Blomberg, B Mary E; Scheper, Rik J; van Hoogstraten, Ingrid M W

    2016-02-15

    Oral metal exposure has been associated with diverse adverse reactions, including neurotoxicity. We showed previously that dentally applied metals activate dendritic cells (MoDC) via TLR4 (Ni, Co, Pd) and TLR3 (Au). It is still unknown whether the low levels of dental metals reaching the brain can trigger local innate cells or prime them to become more responsive. Here we tested whether dentally applied metals (Cr, Fe, Co, Ni, Cu, Zn, Au, Hg) activate primary human microglia in vitro and, as a model, monocytic THP-1-cells, in high non-toxic as well as near-physiological concentrations. In addition the effects of 'near-physiological' metal exposure on endotoxin (LPS) responsiveness of these cells were evaluated. IL-8 and IL-6 production after 24h was used as read out. In high, non-toxic concentrations all transition metals except Cr induced IL-8 and IL-6 production in microglia, with Ni and Co providing the strongest stimulation. When using near-physiological doses (up to 10× the normal plasma concentration), only Zn and Cu induced significant IL-8 production. Of note, the latter metals also markedly potentiated LPS responsiveness of microglia and THP-1 cells. In conclusion, transition metals activate microglia similar to MoDCs. In near-physiological concentrations Zn and Cu are the most effective mediators of innate immune activation. A clear synergism between innate responses to Zn/Cu and LPS was observed, shedding new light on the possible relation between oral metal exposure and neurotoxicity.

  3. The efficiency of Amberlite XAD-4 resin loaded with 1-(2-pyridylazo)-2-naphthol in preconcentration and separation of some toxic metal ions by flame atomic absorption spectrometry.

    Science.gov (United States)

    Islam, Aminul; Laskar, Mohammad Asaduddin; Ahmad, Akil

    2011-04-01

    A selective method has been developed for the determination of trace amount of metal ions after preconcentration on 1-(2-pyridylazo)-2-naphthol loaded Amberlite XAD-4 resin. The chelating resin was characterized on the basis of infra red spectra, thermal and chemical stability, and hydrogen ion capacity. High preconcentration factor of 160-400 up to a low preconcentration limit of 10 μg L(-1) has been achieved for almost all the metals. The chelating resin was highly selective even in the presence of large concentrations of alkali and alkaline earth metals and various matrix components. Chromatographic separation of metal ions in binary mixtures has been accomplished. The analytical utility of the resin for metal ions was explored by analyzing natural water and standard reference materials.

  4. 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

  5. Metal ion interpretation in resurfacing versus conventional hip arthroplasty and in whole blood versus serum. How should we interpret metal ion data

    NARCIS (Netherlands)

    Smolders, J.M.; Bisseling, P.; Hol, A.; Straeten, C. Van Der; Schreurs, B.W.; Susante, J.L.C. van

    2011-01-01

    Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure, and both serum and whole blood measurements are used in clinical practice. This study provides a guideline for interpretation of metal ion analysis in clin

  6. Capacitance of the double electrical layer on the copper-group metals in molten alkali metal halides

    Science.gov (United States)

    Kirillova, E. V.; Stepanov, V. P.

    2016-08-01

    The electrochemical impedance is measured to study the capacitance of the double electrical layer of metallic Au, Ag, and Cu as a function of potential and temperature in nine molten salts, namely, the chlorides, bromides, and iodides of sodium, potassium, and cesium. The C- E curve of a gold electrode has an additional minimum in the anodic branch. This minimum for silver is less pronounced and is only observed at low ac signal frequencies in cesium halides. The additional minimum is not detected for copper in any salt under study. This phenomenon is explained on the assumption that the adsorption of halide anions on a positively charged electrode surface has a predominantly chemical rather than an electrostatic character. The specific adsorption in this case is accompanied by charge transfer through the interface and the formation of an adsorbent-adsorbate covalent bond.

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

    CERN Document Server

    Kaur, Kiranpreet; Sahoo, B K

    2015-01-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients ($C_3$s) of the alkali ions (Li$^+$, Na$^+$, K$^+$ and Rb$^+$), the alkaline-earth ions (Ca$^+$, Sr$^+$, Ba$^+$ and Ra$^+$) and the inert gas atoms (He, Ne, Ar and Kr) with a graphene layer are determined precisely within the framework of Dirac model. For these calculations, we have evaluated the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are, finally, given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at the room temperature.

  8. Interactions Between Metal Ions and Carbohydrates: Coordination Behavior of D-Ribose to Lanthanide Ions

    Institute of Scientific and Technical Information of China (English)

    苏允兰; 杨丽敏; 翁诗甫; 吴瑾光

    2002-01-01

    Lanthanum chloride α-D-ribopyranose pentahydrate complex was prepared and speculated its structure from the similar IR spectra of corresponding praseodymium and neodymium-D-ribose complexes, which reveal the coordination behavior of D-ribose to lanthanide ions and give us a model of the interactions between metal ions and carbohydrates.

  9. Ab Initio Molecular Dynamics Study on the Interactions between Carboxylate Ions and Metal Ions in Water.

    Science.gov (United States)

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Trinh, Thuat T; Grimes, Brian A

    2015-08-20

    The interaction between a carboxylate anion (deprotonated propanoic acid) and the divalent Mg(2+), Ca(2+), Sr(2+), Ba(2+) metal ions is studied via ab initio molecular dynamics. The main focus of the study is the selectivity of the carboxylate-metal ion interaction in aqueous solution. The interaction is modeled by explicitly accounting for the solvent molecules on a DFT level. The hydration energies of the metal ions along with their diffusion and mobility coefficients are determined and a trend correlated with their ionic radius is found. Subsequently, a series of 16 constrained molecular dynamics simulations for every ion is performed, and the interaction free energy is obtained from thermodynamic integration of the forces between the metal ion and the carboxylate ion. The results indicate that the magnesium ion interacts most strongly with the carboxylate, followed by calcium, strontium, and barium. Because the interaction free energy is not enough to explain the selectivity of the reaction observed experimentally, more detailed analysis is performed on the simulation trajectories to understand the steric changes in the reaction complex during dissociation. The solvent dynamics appear to play an important role during the dissociation of the complex and also in the observed selectivity behavior of the divalent ions.

  10. Promoting oxygen vacancy formation and p-type conductivity in SrTiO3via alkali metal doping: a first principles study.

    Science.gov (United States)

    Triggiani, Leonardo; Muñoz-García, Ana B; Agostiano, Angela; Pavone, Michele

    2016-10-19

    Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

  11. Reducing hazardous heavy metal ions using mangium bark waste.

    Science.gov (United States)

    Khabibi, Jauhar; Syafii, Wasrin; Sari, Rita Kartika

    2016-08-01

    The objective of this study was to evaluate the characteristics of mangium bark and its biosorbent ability to reduce heavy metal ions in standard solutions and wastewater and to assess changes in bark characteristics after heavy metal absorption. The experiments were conducted to determine heavy metal absorption from solutions of heavy metals alone and in mixtures as well as from wastewater. The results show that mangium bark can absorb heavy metals. Absorption percentages and capacities from single heavy metal solutions showed that Cu(2+) > Ni(2+) > Pb(2+) > Hg(2+), while those from mixture solutions showed that Hg(2+) > Cu(2+) > Pb(2+) > Ni(2+). Wastewater from gold mining only contained Cu, with an absorption percentage and capacity of 42.87 % and 0.75 mg/g, respectively. The highest absorption percentage and capacity of 92.77 % and 5.18 mg/g, respectively, were found for Hg(2+) in a mixture solution and Cu(2+) in single-metal solution. The Cu(2+) absorption process in a single-metal solution changed the biosorbent characteristics of the mangium bark, yielding a decreased crystalline fraction; changed transmittance on hydroxyl, carboxyl, and carbonyl groups; and increased the presence of Cu. In conclusion, mangium bark biosorbent can reduce hazardous heavy metal ions in both standard solutions and wastewater.

  12. Coordination Chemistry of Alkali and Alkaline-Earth Cations with Macrocyclic Ligands.

    Science.gov (United States)

    Dietrich, Bernard

    1985-01-01

    Discusses: (l) alkali and alkaline-earth cations in biology (considering naturally occurring lonophores, their X-ray structures, and physiochemical studies); (2) synthetic complexing agents for groups IA and IIA; and (3) ion transport across membranes (examining neutral macrobicyclic ligands as metal cation carriers, transport by anionic carriers,…

  13. Sensitive Determination of DNA by RLS Enhancement of Metal Ions

    Institute of Scientific and Technical Information of China (English)

    Huang Jian-ping; Chen Fang; Ai Xin-ping; He Zhi-ke

    2004-01-01

    The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group ⅠB and ⅡB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2+. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10-8-4×10-6 g·5mL-1 and 1.13×10-8 g·5mL-1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA of Bacillus subtilis DB104.

  14. Low coefficient of thermal expansion polyimides containing metal ion additives

    Science.gov (United States)

    Stoakley, D. M.; St. Clair, A. K.

    1992-01-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The incorporation of metal ion-containing additives into polyimides, resulting in significantly lowered CTE's, has been studied. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12 percent to over 100 percent depending on the choice of additive and its concentration.

  15. Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; SHI Caijun; SONG Jianming

    2009-01-01

    The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated.Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re-placement of cement with 25% glass powder slightly decreases the strengthes at 7 and 28 d, but shows no effect on 90 d's. Silica fume is very effective in improving both the strength and chloride penetra-tion resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.

  16. Determination of Some Heavy-metal-ions Using a Sulfur Ion Modified BZ Oscillating System

    Institute of Scientific and Technical Information of China (English)

    Hua CHEN; Wu YANG; Hong Xia DAI; Xiao Xia WEI; Jie QU; Jin Zhang GAO

    2006-01-01

    A highly sensitive method is developed for the determination of trace amounts of some heavy metal ions in aqueous solution based on the classical Belousov-Zhabotinskii (BZ) oscillating chemical system. Introducing of S2- ion makes the new oscillating system Ce(SO4)2 - KBrO3-CH2(COOH)2 - Na2S - H2SO4 have to a high sensitivity for some heavy metal ions such as Ag+,pb2+, Hg2+, Cd2+, Cu2+and Bi3+ with detection limits down to 10-12 mol. L-1.

  17. A new approach for understanding ion transport in glasses; example of complex alkali diborate glasses containing lead, bismuth and tellurium oxides

    Indian Academy of Sciences (India)

    V C Veeranna Gowda; C Narayana Reddy; K J Rao

    2013-02-01

    Mechanism of ion transport in glasses continues to be incompletely understood. Several of the theoretical models in vogue fail to rationalize conductivity behaviour when d.c. and a.c. measurements are considered together. While they seem to involve the presence of at least two components in d.c. activation energy, experiments fail to reveal that feature. Further, only minor importance is given to the influence of structure of the glass on the ionic conductivity behaviour. In this paper, we have examined several general aspects of ion transport taking the example of ionically conducting glasses in pseudo binary, Na2B4O7.(1−) M$_{a}$O$_{b}$ (with = 0.25–0.79 and M$_{a}$O$_{b}$ = PbO, TeO2 and Bi2O3) system of glasses which have also been recently characterized. Ion transport in them has been studied in detail. We have proposed that non-bridging oxygen (NBO) participation is crucial to the understanding of the observed conductivity behaviour. NBO–BO switching is projected as the first important step in ion transport and alkali ion jump is a subsequent event with a characteristically lower barrier which is, therefore, not observed in any study. All important observations in d.c. and a.c. transport in glasses are found consistent with this model.

  18. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111)

    Science.gov (United States)

    Xin, Hongliang; Linic, Suljo

    2016-06-01

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  19. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    Science.gov (United States)

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

    2014-04-29

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  20. Crystal Structure and Topological Aspects of the High-Temperature Phases of the Alkali-metal Oxalates M-2 C2O4(M= K,Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Dinnebier,R.; Vensky, S.; Jensen, M.; Hanson, J.

    2005-01-01

    The high-temperature phases of the alkali-metal oxalates M{sub 2}[C{sub 2}O{sub 4}] (M=K, Rb, Cs), and their decomposition products M{sub 2}[CO{sub 3}] (M=K, Rb, Cs), were investigated by fast, angle-dispersive X-ray powder diffraction with an image-plate detector, and also by simultaneous differential thermal analysis (DTA)/thermogravimetric analysis (TGA)/mass spectrometry (MS) and differential scanning calorimetry (DSC) techniques. The following phases, in order of decreasing temperature, were observed and crystallographically characterized (an asterisk denotes a previously unknown modification): *{alpha}-K{sub 2}[C{sub 2}O{sub 4}], *{alpha}-Rb{sub 2}[C{sub 2}O{sub 4}], *{alpha}-Cs{sub 2}[C{sub 2}O{sub 4}], {alpha}-K{sub 2}[CO{sub 3}], *{alpha}-Rb{sub 2}[CO{sub 3}], and *{alpha}-Cs{sub 2}[CO{sub 3}] in space group P6{sub 3}/mmc; *{beta}-Rb{sub 2}[C{sub 2}O{sub 4}], *{beta}-Cs{sub 2}[C{sub 2}O{sub 4}], *{beta}-Rb{sub 2}[CO{sub 3}], and *{beta}-Cs{sub 2}[CO{sub 3}] in Pnma; {gamma}-Rb{sub 2}[C{sub 2}O{sub 4}], {gamma}-Cs[C{sub 2}O{sub 4}], {gamma}-Rb{sub 2}[CO{sub 3}], and {gamma}-Cs{sub 2}[CO{sub 3}] in P2{sub 1}/c; and {delta}-K{sub 2}[C{sub 2}O{sub 4}] and {delta}-Rb{sub 2}[C{sub 2}O{sub 4}] in Pbam. With respect to the centers of gravity of the oxalate and carbonate anions, respectively, the crystal structures of all known alkali-metal oxalates and carbonates belong to the AlB{sub 2} family, and adopt either the AlB{sub 2} or the Ni{sub 2}In arrangement depending on the size of the cation and the temperature. Despite the different sizes and constitutions of the carbonate and oxalate anions, the high-temperature phases of the alkali-metal carbonates M{sub 2}[CO{sub 3}] (M=K, Rb, Cs), exhibit the same sequence of basic structures as the corresponding alkali-metal oxalates. The topological aspects and order-disorder phenomena at elevated temperature are discussed.

  1. Nano sized carbonized waste biomass for heavy metal ion remediation

    Directory of Open Access Journals (Sweden)

    Mahajan Garima

    2014-12-01

    Full Text Available Utilization of agricultural waste material with approach to enhance the heavy metal remediation properties by carbonizing the biomass at nano size particles has been explored in present investigation from aqueous solutions. In this study the lignocellulosic, nitrogenous agricultural waste biomass Delbergia sissoo pods (DSP has been tried for sequestering of Cd (II, Pb (II and Ni (II metal ions from aqueous solutions. Batch experiments were performed for removal of targeted metal ions keeping in consideration the preliminary affecting parameters such as effect of adsorption dose, pH, initial metal ion concentration, stirring speed and contact time. The sorption studies were analyzed by using, Freundlic isotherm and Langmuir isotherm models. The kinetics of the process was evaluated by pseudo pseudo-first order and pseudo second order kinetic models. Studies reveal that the equilibrium was achieved with in 30 min of the contact time at optimized parameters. Analytical studies of biosorbent were done by means of FT-IR, SEM and XRD. Desorption experiments were carried out using HCl solution with a view to regenerate the spent adsorbent and to recover the adsorbed metal ions.

  2. Smart responsive microcapsules capable of recognizing heavy metal ions.

    Science.gov (United States)

    Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

    2010-09-15

    Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions.

  3. Metal-Ion Additives Reduce Thermal Expansion Of Polyimides

    Science.gov (United States)

    Stoakley, Diane M.; St. Clair, Anne K.; Emerson, Burt R., Jr.; Willis, George L.

    1994-01-01

    Polyimides widely used as high-performance polymers because of their excellent thermal stability and toughness. However, their coefficients of thermal expansion (CTE's) greater than those of metals, ceramics, and glasses. Decreasing CTE's of polyimides increase usefulness for aerospace and electronics applications in which dimensional stability required. Additives containing metal ions reduce coefficients of thermal expansion of polyimides. Reductions range from 11 to over 100 percent.

  4. Spectrum, radial wave functions, and hyperfine splittings of the Rydberg states in heavy alkali-metal atoms

    Science.gov (United States)

    Sanayei, Ali; Schopohl, Nils

    2016-07-01

    We present numerically accurate calculations of the bound-state spectrum of the highly excited valence electron in the heavy alkali-metal atoms solving the radial Schrödinger eigenvalue problem with a modern spectral collocation method that applies also for a large principal quantum number n ≫1 . As an effective single-particle potential we favor the reputable potential of Marinescu et al. [Phys. Rev. A 49, 982 (1994)], 10.1103/PhysRevA.49.982. Recent quasiclassical calculations of the quantum defect of the valence electron agree for orbital angular momentum l =0 ,1 ,2 ,... overall remarkably well with the results of the numerical calculations, but for the Rydberg states of rubidium and also cesium with l =3 this agreement is less fair. The reason for this anomaly is that in rubidium and cesium the potential acquires for l =3 deep inside the ionic core a second classical region, thus invalidating a standard Wentzel-Kramers-Brillouin (WKB) calculation with two widely spaced turning points. Comparing then our numerical solutions of the radial Schrödinger eigenvalue problem with the uniform analytic WKB approximation of Langer constructed around the remote turning point rn,j ,l (" close=")n -δ0)">+ we observe everywhere a remarkable agreement, apart from a tiny region around the inner turning point rn,j ,l (-). For s states the centrifugal barrier is absent and no inner turning point exists: rn,j ,0 (-)=0 . With the help of an ansatz proposed by Fock we obtain for the s states a second uniform analytic approximation to the radial wave function complementary to the WKB approximation of Langer, which is exact for r →0+ . From the patching condition, that is, for l =0 the Langer and Fock solutions should agree in the intermediate region 0 application we consider recent spectroscopic data for the hyperfine splittings of the isotopes 85Rb and 87Rb and find a remarkable agreement with the predicted scaling relation An,j ,0 (HFS )=const .

  5. Removal and recovery of toxic metal ions from aqueous waste sites using polymer pendant ligands

    Energy Technology Data Exchange (ETDEWEB)

    Fish, D. [Lawrence Berkeley National Lab., CA (United States)

    1996-10-01

    The purpose of this project is to investigate the use of polymer pendant ligand technology to remove and recover toxic metal ions from DOE aqueous waste sites. Polymer pendant lgiands are organic ligands, anchored to crosslinked, modified divinylbenzene-polystyrene beads, that can selectively complex metal ions. The metal ion removal step usually occurs through a complexation or ion exchange phenomena, thus recovery of the metal ions and reuse of the beads is readily accomplished.

  6. Metal ions and RNA folding: a highly charged topic with a dynamic future.

    Science.gov (United States)

    Woodson, Sarah A

    2005-04-01

    Metal ions are required to stabilize RNA tertiary structure and to begin the folding process. How different metal ions enable RNAs to fold depends on the electrostatic potential of the RNA and correlated fluctuations in the positions of the ions themselves. Theoretical models, fluorescence spectroscopy, small angle scattering and structural biology reveal that metal ions alter the RNA dynamics and folding transition states. Specifically coordinated divalent metal ions mediate conformational rearrangements within ribozyme active sites.

  7. Metal ion release from electric guitar strings in artificial sweat

    Energy Technology Data Exchange (ETDEWEB)

    Rezic, Iva [Department of Applied Chemistry, Faculty of Textile Technology, University of Zagreb, Prilaz Baruna Filipovica 28a, 10000 Zagreb (Croatia)], E-mail: iva_rezic@net.hr; Curkovic, Lidija [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb (Croatia); Ujevic, Magdalena [Croatian Institute of Public Health, Zagreb, Croatia (Croatia)

    2009-09-15

    The aim of this study was to monitor the dissolution of metal ions from electric guitar strings. For characterization of investigated strings, two independent methods of analysis were chosen: ICP-OES and AAS. Electric guitar strings consisted of two separate parts: Sn-plated steel core wire which was hexagonal in cross section and Ni-plated steel wrap which was round in cross section. Dissolution of Ni{sup 2+}, Mn{sup 2+}, Si{sup 4+}, Sn{sup 2+} and Fe{sup 3+} ions from electric guitar strings E6 and D4 were measured as a function of time in artificial sweat solution, at temperature of 37 deg. C according to the EN 1811:1999 standard test procedure. The determination of the amount of the metal ions released in the corrosive solutions was carried out by means of inductively coupled plasma-optical emission spectroscopy (ICP-OES). The mechanism of metal ions eluted in artificial sweat is discussed. The concentrations of dissolved metal ions in corrosive solution from E6 and D4 strings are decreasing in the following order: Fe{sup 3+} > Sn{sup 2+} > Mn{sup 2+} > Si{sup 4+} > Ni{sup 2+}. Among all investigated metal ions, nickel is far the most allergenic. Since the amounts of the eluted Ni{sup 2+} did not exceed 0.5 {mu}g cm{sup -2} week{sup -1}, the investigated electric guitar strings should not induce contact dermatitis.

  8. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

    Science.gov (United States)

    Lee, Chuping; Lu, I.-Chung; Hsu, Hsu Chen; Lin, Hou-Yu; Liang, Sheng-Ping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2016-09-01

    In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

  9. 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

    2015-08-05

    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.

  10. Atomic arrangement and electron band structure of Si(1 1 1)-ß-\\sqrt{3}\\times \\sqrt{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)\\sqrt{3}× \\sqrt{3} -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 {{T}4} 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)\\sqrt{3}× \\sqrt{3} -Bi surfaces modified by alkali metal adsorption as a set of material systems showing promise for spintronic applications.

  11. Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties

    DEFF Research Database (Denmark)

    Jantzen, Christopher; Jørgensen, Henrik L; Duus, Benn R

    2013-01-01

    Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.......Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties....

  12. Metal ion levels and revision rates in metal-on-metal hip resurfacing arthroplasty: a comparative study.

    Science.gov (United States)

    Robinson, Patrick G; Wilkinson, Andrew J; Meek, Robert M D

    2014-01-01

    Metal-on-metal (MoM) bearings in hip surgery are related to increased blood levels of metal ions. The nature of the relationship between ion levels and failure is still not fully understood. This study compares three cohorts of patients, 120 patients in each cohort, treated with a hip resurfacing arthroplasty, grouped by brand and diameter of femoral component on average four years postoperatively: Birmingham Hip Resurfacing ≥50 mm, Durom resurfacing ≥50 mm and Durom resurfacing resurfacing than the other two cohorts (P<0.05). The large BHR and large Durom HRA had revision rates of 3.3%. The small Durom HRA had a revision rate of 8.3%. Elevated blood ion levels can indicate a failing MoM bearing. The large BHR and large Durom HRA have similar revision rates yet the large Durom HRA had significantly lower metal ion levels. When similar ion levels were reported for BHR and small Durom the latter had significantly higher revision rates. This suggests ion levels do not absolutely predict the rate of HRA failure. Since MoM generation of metal ions is not the sole reason of failure, regular clinical and radiographic follow-up should also be in place for patients with these joints.

  13. Dimeric Complexes of Tryptophan with M2+ Metal Ions

    NARCIS (Netherlands)

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

    2009-01-01

    IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and tra

  14. Stripping chronopotentiometry for metal ion speciation analysis at a microelectrode

    NARCIS (Netherlands)

    Leeuwen, van H.P.; Town, R.

    2002-01-01

    The features of metal ion speciation determination by stripping chronopotentiometry (SCP) at a microelectrode are examined and compared with those of DP-SV. SCP measurements are essentially of a steady-state nature under experimentally achievable conditions and correspond to practically complete dep

  15. Novel Alkali-Metal Coordination in Phenoxides: Powder Diffraction Results on C(6)H(5)OM (M = Li, Na, K, Rb, Cs).

    Science.gov (United States)

    Dinnebier, R. E.; Pink, Maren; Sieler, J.; Stephens, P. W.

    1997-07-30

    We report the ab initio structure solutions of C(6)H(5)OM (M = K, Rb, Cs) by high-resolution powder X-ray diffraction. The compounds, which are of interest for reactions of the Kolbe-Schmitt type, are isostructural. The crystal structures are orthorhombic, space group Pna2(1), Z = 12, with lattice parameters (a, b, c in Å) 14.1003(1), 17.9121(1), and 7.16475(1) for the K compound, 14.4166(2), 18.2028(2), and 7.4009(1) for the Rb compound, and 14.8448(2), 18.5070(2), and 7.6306(1) for the Cs compound. They have a chain structure [M([6])] along the crystallographic c axis. This is a very unusual arrangement in which two different alkali-metal coordination spheres are observed: a distorted octahedron and a 3-fold oxygen coordination. In the latter, the 3-fold-coordinated unsaturated alkali metals additionally show weak interactions with phenyl rings. We also give powder patterns for the compounds with M = Li, Na. The former crystallizes in the monoclinic space group P2(1)/a with lattice parameters a = 22.594 Å, b = 4.7459 Å, c= 10.053 Å, and beta = 97.82 degrees with Z = 8, but no structure solution was possible. The powder pattern for the Na phenolate is in agreement with the earlier single-crystal structure.

  16. Removal of toxic metal ions with magnetic hydrogels.

    Science.gov (United States)

    Ozay, Ozgur; Ekici, Sema; Baran, Yakup; Aktas, Nahit; Sahiner, Nurettin

    2009-09-01

    Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions.

  17. Chitosan Removes Toxic Heavy Metal Ions from Cigarette Mainstream Smoke

    Institute of Scientific and Technical Information of China (English)

    ZHOU Wen; XU Ying; WANG Dongfeng; ZHOU Shilu

    2013-01-01

    This study investigated the removal of heavy metal ions from cigarette mainstream smoke using chitosan.Chitosan of various deacetylation degrees and molecular weights were manually added to cigarette filters in different dosages.The mainstream smoke particulate matter was collected by a Cambridge filter pad,digested by a microwave digestor,and then analyzed for contents of heavy metal ions,including As(Ⅲ/Ⅴ),Pb(Ⅱ),Cd(Ⅱ),Cr(Ⅲ/Ⅵ) and Ni(Ⅱ),by graphite furnace atomic absorption spectrometry (GFAAS).The results showed that chitosan had a removal effect on Pb(Ⅱ),Cd(Ⅱ),Cr(Ⅲ/Ⅵ) and Ni(Ⅱ).Of these,the percent removal of Ni(Ⅱ) was elevated with an increasing dosage of chitosan.Chitosan of a high deace tylation degree exhibited good binding performance toward Cd(Ⅱ),Cr(Ⅲ/Ⅵ) and Ni(Ⅱ),though with poor efficiency for Pb(Ⅱ).Except As(Ⅲ/Ⅴ),all the tested metal ions showed similar tendencies in the growing contents with an increasing chitosan molecular weight.Nonetheless,the percent removal of Cr(Ⅲ/Ⅵ) peaked with a chitosan molecular weight of 200 kDa,followed by a dramatic decrease with an increasing chitosan molecular weight.Generally,chitosan had different removal effects on four out of five tested metal ions,and the percent removal of Cd(Ⅱ),Pb(Ⅱ),Cr(Ⅲ/Ⅵ) and Ni(Ⅱ) was approximately 55%,45%,50%,and 16%,respectively.In a word,chitosan used in cigarette filter can remove toxic heavy metal ions in the mainstream smoke,improve cigarette safety,and reduce the harm to smokers.

  18. Independent cross-sections of alkali isotopes produced in various targets bombarded by $^{12}C$ and $^{18}O$ ions up to 77 MeV/amu

    CERN Document Server

    De Saint-Simon, M; Coc, A; Epherre-Rey-Campagnolle, Marcelle; Guimbal, P; Haan, S; Langevin, M; Müller, A C; Thibault, C; Touchard, F

    1982-01-01

    The authors report on an online mass-spectrometric study of the isotopic distributions of nuclear reaction products. The two purposes of this experiment are the investigation of a particular aspect of reaction-mechanisms and the study of the possibility for exotic-nuclei production. The measurements have been carried out with the 86 MeV/amu /sup 12/C and /sup 18/O beams of the synchrocyclotron SC (CERN). By degradation in different sets of graphite slabs, three different energies: 13, 27 and 77 MeV/amu have been chosen. Due to the chemical selectivity for the alkali elements of the device, the isotopic distributions of Li, Na, K, Rb, Cs and Fr were measured in four targets: C, Nb, Ta and U. The independent yields obtained by direct ion counting are converted in cross-sections using a calibration of T. Lund et al.

  19. Solution NMR refinement of a metal ion bound protein using metal ion inclusive restrained molecular dynamics methods

    Energy Technology Data Exchange (ETDEWEB)

    Chakravorty, Dhruva K.; Wang Bing [University of Florida, Department of Chemistry and the Quantum Theory Project (United States); Lee, Chul Won [Chonnam National University, Department of Chemistry (Korea, Republic of); Guerra, Alfredo J.; Giedroc, David P., E-mail: giedroc@indiana.edu [Indiana University, Department of Chemistry (United States); Merz, Kenneth M., E-mail: kmerz1@gmail.com [University of Florida, Department of Chemistry and the Quantum Theory Project (United States)

    2013-06-15

    Correctly calculating the structure of metal coordination sites in a protein during the process of nuclear magnetic resonance (NMR) structure determination and refinement continues to be a challenging task. In this study, we present an accurate and convenient means by which to include metal ions in the NMR structure determination process using molecular dynamics (MD) simulations constrained by NMR-derived data to obtain a realistic and physically viable description of the metal binding site(s). This method provides the framework to accurately portray the metal ions and its binding residues in a pseudo-bond or dummy-cation like approach, and is validated by quantum mechanical/molecular mechanical (QM/MM) MD calculations constrained by NMR-derived data. To illustrate this approach, we refine the zinc coordination complex structure of the zinc sensing transcriptional repressor protein Staphylococcus aureus CzrA, generating over 130 ns of MD and QM/MM MD NMR-data compliant sampling. In addition to refining the first coordination shell structure of the Zn(II) ion, this protocol benefits from being performed in a periodically replicated solvation environment including long-range electrostatics. We determine that unrestrained (not based on NMR data) MD simulations correlated to the NMR data in a time-averaged ensemble. The accurate solution structure ensemble of the metal-bound protein accurately describes the role of conformational sampling in allosteric regulation of DNA binding by zinc and serves to validate our previous unrestrained MD simulations of CzrA. This methodology has potentially broad applicability in the structure determination of metal ion bound proteins, protein folding and metal template protein-design studies.

  20. 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.

  1. Kinetic study of heavy metal ions removal by ion exchange in batch conical air spouted bed

    Directory of Open Access Journals (Sweden)

    T.M. Zewail

    2015-03-01

    Full Text Available Spouted bed contactor is a hybrid of fixed and fluidized bed contactors, which retains the advantages of each with good hydrodynamic conditions. The aim of the present study is to investigate the performance of a batch conical air spouted vessel for heavy metal removal by strong cation exchange resins (AMBERJET 1200 Na. The effect of various parameters such as type of heavy metal ions (Ni+2 and Pb+2, contact time, superficial air velocity and initial heavy metal ion concentration on % heavy metal ion removal has been investigated. It has been found that under optimum conditions 98% and 99% removal of Ni+2 and Pb+2 were achieved respectively. Several kinetic models were used to test the experimental data and to examine the controlling mechanism of the sorption process. The present results of Ni+2 and Pb+2 well fit pseudo second order kinetic model with a high correlation coefficient. Both film diffusion and intra-particle diffusion contribute to the ion exchange process. The present study revealed that spouted bed vessel may provide an effective alternative for conducting ion exchange reactions.

  2. Development of a four-zone carousel process packed with metal ion-imprinted polymer for continuous separation of copper ions from manganese ions, cobalt ions, and the constituent metal ions of the buffer solution used as eluent.

    Science.gov (United States)

    Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong

    2011-08-19

    A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time.

  3. Dispersion C3 coefficients for the alkali-metal atoms interacting with a graphene layer and with a carbon nanotube

    CERN Document Server

    Arora, Bindiya; Sahoo, B K

    2013-01-01

    We evaluate separation dependent van der Waal dispersion ($C_3$) coefficients for the interactions of the Li, Na, K and Rb alkali atoms with a graphene layer and with a single walled carbon nanotube (CNT) using the hydrodynamic and Dirac models. The results from both the models are evaluated using accurate values of the dynamic polarizabilities of the above atoms. Accountability of these accurate values of dynamical polarizabilities of the alkali atoms in determination of the above $C_3$ coefficients are accentuated by comparing them with the coefficients evaluated using the dynamic dipole polarizabilities estimated from the single oscillator approximation which are typically employed in the earlier calculations. For practical description of the atom-surface interaction potentials the radial dependent $C_3$ coefficients are given for a wide range of separation distances between the ground states of the considered atoms and the wall surfaces and also for different values of nanotube radii. The coefficients for...

  4. Methods for synthesizing metal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  5. Ion beam mixing isotopic metal bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  6. Liquid metal alloy ion sources—An alternative for focussed ion beam technology

    Science.gov (United States)

    Bischoff, Lothar; Mazarov, Paul; Bruchhaus, Lars; Gierak, Jacques

    2016-06-01

    Today, Focused Ion Beam (FIB) processing is nearly exclusively based on gallium Liquid Metal Ion Sources (LMIS). But, many applications in the μm- or nm range could benefit from ion species other than gallium: local ion implantation, ion beam mixing, ion beam synthesis, or Focused Ion Beam Lithography (IBL). Therefore, Liquid Metal Alloy Ion Sources (LMAIS) represent a promising alternative to expand the remarkable application fields for FIB. Especially, the IBL process shows potential advantages over, e.g., electron beam or other lithography techniques: direct, resistless, and three-dimensional patterning, enabling a simultaneous in-situ process control by cross-sectioning and inspection. Taking additionally into account that the used ion species influences significantly the physical and chemical nature of the resulting nanostructures—in particular, the electrical, optical, magnetic, and mechanic properties leading to a large potential application area which can be tuned by choosing a well suited LMAIS. Nearly half of the elements of the periodic table are recently available in the FIB technology as a result of continuous research in this area during the last forty years. Key features of a LMAIS are long life-time, high brightness, and stable ion current. Recent developments could make these sources feasible for nano patterning issues as an alternative technology more in research than in industry. The authors will review existing LMAIS, LMIS other than Ga, and binary and ternary alloys. These physical properties as well as the fabrication technology and prospective domains for modern FIB applications will similarly be reviewed. Other emerging ion sources will be also presented and their performances discussed.

  7. Peptide immobilisation on porous silicon surface for metal ions detection

    Directory of Open Access Journals (Sweden)

    Chazalviel Jean-Noël

    2011-01-01

    Full Text Available Abstract In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization. The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II/Cu(I couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  8. Peptide immobilisation on porous silicon surface for metal ions detection

    Science.gov (United States)

    Sam, Sabrina S.; Chazalviel, Jean-Noël Jn; Gouget-Laemmel, Anne Chantal Ac; Ozanam, François F.; Etcheberry, Arnaud A.; Gabouze, Nour-Eddine N.

    2011-06-01

    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl- N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization. The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  9. Peptide immobilisation on porous silicon surface for metal ions detection.

    Science.gov (United States)

    Sam, Sabrina S; Chazalviel, Jean-Noël Jn; Gouget-Laemmel, Anne Chantal Ac; Ozanam, François F; Etcheberry, Arnaud A; Gabouze, Nour-Eddine N

    2011-01-01

    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization.The property of peptides to form stable complexes with metal ions is exploited to achieve metal-ion recognition by the peptide-modified PSi-based biosensor. An electrochemical study of the GlyHisGlyHis-modified PSi electrode is achieved in the presence of copper ions. The recorded cyclic voltammograms show a quasi-irreversible process corresponding to the Cu(II)/Cu(I) couple. The kinetic factors (the heterogeneous rate constant and the transfer coefficient) and the stability constant of the complex formed on the porous silicon surface are determined. These results demonstrate the potential role of peptides grafted on porous silicon in developing strategies for simple and fast detection of metal ions in solution.

  10. Optical studies of ion-beam synthesized metal alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Magudapathy, P., E-mail: pmp@igcar.gov.in; Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603 102 India (India)

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  11. New Catalytic DNA Biosensors for Radionuclides and Metal ion

    Energy Technology Data Exchange (ETDEWEB)

    Yi Lu

    2008-03-01

    We aim to develop new DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides, such as uranium, technetium, and plutonium, and metal contaminants, such as lead, chromium, and mercury. The sensors will be highly sensitive and selective. They will be applied to on-site, real-time assessment of concentration, speciation, and stability of the individual contaminants before and during bioremediation, and for long-term monitoring of DOE contaminated sites. To achieve this goal, we have employed a combinatorial method called “in vitro selection” to search from a large DNA library (~ 1015 different molecules) for catalytic DNA molecules that are highly specific for radionuclides or other metal ions through intricate 3-dimensional interactions as in metalloproteins. Comprehensive biochemical and biophysical studies have been performed on the selected DNA molecules. The findings from these studies have helped to elucidate fundamental principles for designing effective sensors for radionuclides and metal ions. Based on the study, the DNA have been converted to fluorescent or colorimetric sensors by attaching to it fluorescent donor/acceptor pairs or gold nanoparticles, with 11 part-per-trillion detection limit (for uranium) and over million fold selectivity (over other radionuclides and metal ions tested). Practical application of the biosensors for samples from the Environmental Remediation Sciences Program (ERSP) Field Research Center (FRC) at Oak Ridge has also been demonstrated.

  12. Polymer Catalysts Imprinted with Metal Ions as Biomimics of Metalloenzymes

    Directory of Open Access Journals (Sweden)

    Joanna Czulak

    2013-01-01

    Full Text Available This work presents the preparation and properties of molecularly imprinted polymers (MIPs with catalytic centers that mimic the active sites of metalloenzymes. The MIP synthesis was based on suspension polymerization of functional monomers (4-vinylpyridine and acrylonitrile with trimethylolpropane trimethacrylate as a crosslinker in the presence of transition metal ions and 4-methoxybenzyl alcohol as a template. Four metal ions have been chosen for imprinting from among the microelements that are the most essential in the native enzymes: Cu2+, Co2+, Mn2+, and Zn2+. To prepare catalysts, the required loading of metal ions was obtained during sorption process. The catalysts imprinted with Cu2+, Co2+, and Zn2+ were successfully used for hydroquinone oxidation in the presence of hydrogen peroxide. The Mn2+-imprinted catalyst showed no activity due to the insufficient metal loading. Cu2+ MIP showed the highest efficiency. In case of Cu- and Co-MIP catalysts, their activity was additionally increased by the use of surface imprinting technique.

  13. [Applications of metal ions and their complexes in medicine I].

    Science.gov (United States)

    Nagy, László; Csintalan, Gabriella; Kálmán, Eszter; Sipos, Pál; Szvetnik, Attila

    2003-01-01

    The "inorganic medical chemistry" is a rapidly developing field with enormous potential for applications, which offers new possibilities to the pharmaceutical industry. For example, the titanocene dichloride is already in clinical use, and antimetastatic activity of a range of Ru(III) complexes is also well established. There are ways to minimize the toxicity of Gd(III) complexes and therefore they can be safely injected as MRI contrast agents. The so called "ligand design" allows paramagnetic ions to be targeted to specific organs. Such designed ligands also enable the targeting of radiodiagnostic (99mTc) and radiotherapeutic (186Re) isotopes. There is a significant progress in understanding the coordination chemistry and biochemistry of metal ion(s) containing complexes such as Au antiarthritic and Bi antiulcer drugs. Further, currently developing areas include Mn (SOD mimics), V (insulin mimics), Ru (NO scavengers), Ln-based photosensitizers, metal-targeted organic agents and the Fe overload. The expanding knowledge of the role of metals in biochemistry is expected to provide scope for the design of new drugs in many other areas too, for example neuropharmaceutical and antiaffective agents. Progress in coordination chemistry is strongly dependent on understanding not only the thermodynamics of reactions, but also the kinetics of metal complexes under biologically relevant conditions.

  14. Two-photon photoemission investigation of electronic and dynamical properties of alkali atoms adsorbed on noble metal surfaces

    Science.gov (United States)

    Sametoglu, Vahit

    We present a systematic time-resolved two-photon photoemission study of the electronic and dynamical properties of Li through Cs adsorbed on Cu(111) and Ag(111) surfaces. A fundamental problem in surface science is how to describe the electronic structure of a chemisorption interface based on the intrinsic properties of the interacting materials. Because of their simple s-electron structure, elements of the alkali atom group comprise paradigmatic adsorbates in many theories of chemisorption, whereas the complementary experimental studies are sparse and incomplete. Through a combination of spectroscopic and femtosecond time-resolved surface measurements, we are able to probe systematically the binding energies, symmetries, and electron and nuclear relaxation dynamics of the initially unoccupied alkali atom resonances. As a prelude, we study the two-photon photoemission process occurring at the bare Ag(111) surface. We develop a quantitative model for two-photon photoemission process, where the nonresonant and k-dependent two-photon absorption between the lower and upper sp-bands is modeled by the optical Bloch equations, and the angle-dependent intensities are described by the Fresnel equations. Our two-photon photoemission spectra of Li through Cs chemisorbed Cu(111) and Ag(111) surfaces reveal two resonances with the m = 0 and m = +/-1 symmetry ('m' is the projection of the orbital angular momentum 'l' onto the surface plane). For the m = 0 resonance, which is derived from the hybridization of the ns and npz orbitals of alkali atoms, we find a binding energy of 1.84--1.99 eV below the vacuum level, which is independent of the alkali atom period, and tunes with coverage in a universal manner. At 0.3--0.7 eV higher energy, we discover and identify the m = +/-1 resonance by its characteristic angular intensity distribution, which derives from the antisymmetry of the npx and npy orbitals. We implement a quantitative model for the alkali atom chemisorption based on the

  15. Removal of Heavy Metal Ions From Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    maziar noei

    2014-12-01

    Full Text Available The removal of Zn(II, V(II,  by  silica aerogel has been found to be concentration, , contact time, adsorbent dose and temperature dependent. ion exchange are the major removal mechanisms involved. The adsorption isotherm studies clearly indicated that the adsorptive behaviour of metal ions on silica aerogel  was satisfied. The applicability of the Lagergren kinetic model has also been investigated. Thermodynamic constant (Kad , standard free energy ( ∆G0 ,enthalpy (∆H0 and entropy (∆S0 were calculated for predicting the nature of adsorption

  16. Solid-liquid solvent extraction of metal ions

    Institute of Scientific and Technical Information of China (English)

    Bo Peng; Haiyan Fan; Jinzhang Gao

    2003-01-01

    An overview of extraction of some trace metal ions using molten solvent (low melting substance) during last two decadesis presented. The development of this technique since its inception is briefly traced. The comparison of extraction efficiency, thermo-dynamics and kinetics mainly involving extraction of rare earth ions between molten solvent extraction at high temperature and usualliquid-liquid extraction at room temperature are discussed in detail. The various parameters obtained from the previous and presentstudies such as equilibrium extraction constant Kex, pH1/2, thermodynamic and kinetic data are displayed in tabular form. Finally, thecurrent demands, disadvantages and future prospects are also evaluated.

  17. A novel dithiourea and its response to metal ions

    Institute of Scientific and Technical Information of China (English)

    Lu Yuan; Hong Zhong; Li Oing Li; Jing Jing Xiao

    2012-01-01

    The synthesis,characterization,and its response to metal ions of a novel thiourea N,N'-diethoxycarbonyl-N'',N'''-(1,2-ethylidene) dithiourea was reported.The results show that this dithiourea with new structure can react with Cu2+ and Ni2+ separately,and has a best selectivity to Fe3+ ions.Bench-scale flotation tests were also carried out,verifying it has higher copper flotation recovery and better selectivity to sulfide ores containing Cu compared with universal collectors.

  18. Peripheral collisions of highly charged ions with metal clusters

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-Jun; Hu Bi-Tao; Luo Xian-Wen

    2012-01-01

    Within the framework of the dynamical classical over-barrier model,the soft collisions between slow highly charged ions(SHCIs)Ar17+ and the large copper clusters under large impact parameters have been studied in this paper.We present the dominant mechanism of the electron transfer between SHCls and a large metal cluster by computational simulation.The evolution of the occupation of projectile ions,KLχ satellite lines,X-ray yields,Auger electron spectrum and scattering angles are provided.

  19. Design strategies for development of SCR catalyst: improvement of alkali poisoning resistance and novel regeneration method.

    Science.gov (United States)

    Peng, Yue; Li, Junhua; Shi, Wenbo; Xu, Jiayu; Hao, Jiming

    2012-11-20

    Based on the ideas of the additives modification and regeneration method update, two different strategies were designed to deal with the traditional SCR catalyst poisoned by alkali metals. First, ceria doping on the V(2)O(5)-WO(3)/TiO(2) catalyst could promote the SCR performance even reducing the V loading, which resulted in the enhancement of the catalyst's alkali poisoning resistance. Then, a novel method, electrophoresis treatment, was employed to regenerate the alkali poisoned V(2)O(5)-WO(3)/TiO(2) catalyst. This novel technique could dramatically enhance the SCR activities of the alkali poisoned catalysts by removing approximately 95% K or Na ions from the catalyst and showed less hazardous to the environment. Finally, the deactivation mechanisms by the alkali metals were extensively studied by employing both the experimental and DFT theoretical approaches. Alkali atom mainly influences the active site V species rather than W oxides. The decrease of catalyst surface acidity might directly reduce the catalytic activity, while the reducibility of catalysts could be another important factor.

  20. Counterion influence on the vibrational wavenumbers in ternary and quaternary metal hydride salts, A2MH6 (A = alkali metal, alkaline earth, and lanthanides; M = Ir, Fe, Ru, Os, Pt, Mn).

    Science.gov (United States)

    Gilson, Denis F R; Moyer, Ralph O

    2012-02-06

    The wavenumbers of the ν(3) metal-hydrogen stretching mode (T(1u)) in the IR spectra of both ternary and quaternary hexahydrido salts of transition metals from groups 7 to 10 ([Mn(I)H(6)](5-), [Fe(II)H(6)](4-), [Ru(II)H(6)](4-), [Os(II)H(6)](4-), [Ir(III)H(6)](3-), and [Pt(IV)H(6)](2-)) depend linearly upon the ionization energies of the counterions (alkali metal, alkaline earth, and lanthanide) with a separate line for each metal. This relationship provides quantitative support for the charge-transfer mechanism for explaining the stabilities of these compounds.