WorldWideScience

Sample records for alkaline earth atoms

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

    CERN Document Server

    Jiang, Jun; Mitroy, J

    2013-01-01

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

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

    Science.gov (United States)

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

    2009-09-25

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

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

    OpenAIRE

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

    2009-01-01

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

  4. Quantum computing with alkaline-Earth-metal atoms.

    Science.gov (United States)

    Daley, Andrew J; Boyd, Martin M; Ye, Jun; Zoller, Peter

    2008-10-24

    We present a complete scheme for quantum information processing using the unique features of alkaline-earth-metal atoms. We show how two completely independent lattices can be formed for the 1S0 and 3P0 states, with one used as a storage lattice for qubits encoded on the nuclear spin, and the other as a transport lattice to move qubits and perform gate operations. We discuss how the 3P2 level can be used for addressing of individual qubits, and how collisional losses from metastable states can be used to perform gates via a lossy blockade mechanism.

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2008-03-01

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

  7. Tune-out wavelengths for the alkaline earth atoms

    CERN Document Server

    Cheng, Yongjun; Mitroy, Jim

    2013-01-01

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

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

    CERN Document Server

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

    2014-01-01

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

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

    KAUST Repository

    Zhang, J.-Y.

    2013-04-05

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

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

    CERN Document Server

    Derevianko, Andrei; Babb, James F

    2009-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    郅妙婵; 戴长建; 李士本

    2001-01-01

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

  12. Enhancement effect of alkaline earth metal on the determination of aluminium by atomic absorption spectrometry with a graphite furnace

    OpenAIRE

    Matsusaki, Koji

    1987-01-01

    In the determination of aluminium by atomic absorption spectrometry with a graphite furnace, coexisting oxyanion salts of alkaline earth metal enhanced the aluminium atomic absorption. The relative absorbance was increased with decreasing of the ramp atomization rate and with decreasing of the sheathing gas flow rate less than 51 min^. These results show that the enhancement effect is caused by the reductivity of the carbide of alkaline earth metal which is formed in the furnace at ashing and...

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

    OpenAIRE

    Sahin, Hasan; Peeters, Francois M.

    2013-01-01

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

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

    OpenAIRE

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

    2004-01-01

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

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

    CERN Document Server

    Lee, Jeongwon; Noh, Jiho; Mun, Jongchul

    2014-01-01

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

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

    CERN Document Server

    Ciurylo, R; Julienne, P S

    2004-01-01

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

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

    Science.gov (United States)

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

    2013-04-01

    Alkaline-earth-metal atoms can exhibit long-range dipolar interactions, which are generated via the coherent exchange of photons on the (3)P(0) - (3)D(1) transition of the triplet manifold. In the case of bosonic strontium, which we discuss here, this transition has a wavelength of 2.6 μm and a dipole moment of 4.03 D, and there exists a magic wavelength permitting the creation of optical lattices that are identical for the states (3)P(0) and (3)D(1). This interaction enables the realization and study of mixtures of hard-core lattice bosons featuring long-range hopping, with tunable disorder and anisotropy. We derive the many-body master equation, investigate the dynamics of excitation transport, and analyze spectroscopic signatures stemming from coherent long-range interactions and collective dissipation. Our results show that lattice gases of alkaline-earth-metal atoms permit the creation of long-lived collective atomic states and constitute a simple and versatile platform for the exploration of many-body systems with long-range interactions. As such, they represent an alternative to current related efforts employing Rydberg gases, atoms with large magnetic moment, or polar molecules.

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

    CERN Document Server

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

    2012-01-01

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

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

    CERN Document Server

    Yoshimura, M; Uetake, S

    2014-01-01

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

  20. 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.

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

    CERN Document Server

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

    2003-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    CERN Document Server

    Soldán, Pavel; Hutson, Jeremy M

    2009-01-01

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

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

    CERN Document Server

    Chattopadhyay, S; Angom, D

    2014-01-01

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

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

    CERN Document Server

    Daley, Andrew J; Zoller, Peter

    2011-01-01

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

  7. 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...

  8. 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.

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

    CERN Document Server

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

  11. Collective non-equilibrium spin exchange in cold alkaline-earth atomic clocks

    Science.gov (United States)

    Acevedo, Oscar Leonardo; Rey, Ana Maria

    2016-05-01

    Alkaline-earth atomic (AEA) clocks have recently been shown to be reliable simulators of two-orbital SU(N) quantum magnetism. In this work, we study the non-equilibrium spin exchange dynamics during the clock interrogation of AEAs confined in a deep one-dimensional optical lattice and prepared in two nuclear levels. The two clock states act as an orbital degree of freedom. Every site in the lattice can be thought as populated by a frozen set of vibrational modes collectively interacting via predominantly p-wave collisions. Due to the exchange coupling, orbital state transfer between atoms with different nuclear states is expected to happen. At the mean field level, we observe that in addition to the expected suppression of population transfer in the presence of a large magnetic field, that makes the single particle levels off-resonance, there is also an interaction induced suppression for initial orbital population imbalance. This suppression resembles the macroscopic self-trapping mechanism seen in bosonic systems. However, by performing exact numerical solutions and also by using the so-called Truncated Wigner Approximation, we show that quantum correlations can significantly modify the mean field suppression. Our predictions should be testable in optical clock experiments. Project supported by NSF-PHY-1521080, JILA-NSF-PFC-1125844, ARO, AFOSR, and MURI-AFOSR.

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

    OpenAIRE

    Naidon, Pascal; Julienne, Paul S.

    2006-01-01

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

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

    CERN Document Server

    Naidon, P; Julienne, Paul S.; Naidon, Pascal

    2006-01-01

    Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96, 203201], we present the theory for photoassociation and optical Feshbach resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional (2D) optical lattice. In the case of an alkaline-earth intercombination resonance, the narrow natural width of the line makes it possible to observe clear manifestations of the dimensionality, as well as some sensitivity to the scattering length of the atoms. Among possible applications, a 2D lattice may be used to increase the spectroscopic resolution by about one order of magnitude. Furthermore, a 1D lattice induces a shift which provides a new way of determining the strength of a resonance by spectroscopic measurements.

  14. Resonant Rydberg Dressing of Alkaline-Earth Atoms via Electromagnetically Induced Transparency

    Science.gov (United States)

    Gaul, C.; DeSalvo, B. J.; Aman, J. A.; Dunning, F. B.; Killian, T. C.; Pohl, T.

    2016-06-01

    We develop an approach to generate finite-range atomic interactions via optical Rydberg-state excitation and study the underlying excitation dynamics in theory and experiment. In contrast to previous work, the proposed scheme is based on resonant optical driving and the establishment of a dark state under conditions of electromagnetically induced transparency (EIT). Analyzing the driven dissipative dynamics of the atomic gas, we show that the interplay between coherent light coupling, radiative decay, and strong Rydberg-Rydberg atom interactions leads to the emergence of sizable effective interactions while providing remarkably long coherence times. The latter are studied experimentally in a cold gas of strontium atoms for which the proposed scheme is most efficient. Our measured atom loss is in agreement with the theoretical prediction based on binary effective interactions between the driven atoms.

  15. Resonant Rydberg-dressing of Alkaline-Earth Atoms via Electromagnetically Induced Transparency

    CERN Document Server

    Gaul, C; Aman, J A; Dunning, F B; Killian, T C; Pohl, T

    2015-01-01

    We develop an approach to generate finite-range atomic interactions via optical Rydberg-state excitation and study the underlying excitation dynamics in theory and experiment. In contrast to previous work, the proposed scheme is based on resonant optical driving and the establishment of a dark state under conditions of electromagnetically induced transparency. Analyzing the driven dissipative dynamics of the atomic gas, we show that the interplay between coherent light coupling, radiative decay and strong Rydberg-Rydberg atom interactions leads to the emergence of sizeable effective interactions while providing remarkably long coherence times. The latter are studied experimentally in a cold gas of Strontium atoms for which the proposed scheme is most efficient. Our measured atom loss is in excellent agreement with the theoretical prediction based on binary effective interactions between the driven atoms.

  16. Photoassociation spectroscopy of cold alkaline earth atoms near the intercombination line

    OpenAIRE

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

    2004-01-01

    The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between $^{1}S_{0}$ and $^{3}P_{1}$ states) of group II atoms are theoretically investigated. As an example we have carried out a calculation for Calcium atoms colliding at ultra low temperatures of 1 mK, 1 $\\mu$K, and 1 nK. Unlike in most current photoassociation spectroscopy the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using Ca--Ca and ...

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

    CERN Document Server

    Tomza, Michał

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-15

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

  19. Photoassociation spectroscopy of cold alkaline earth atoms near the intercombination line

    CERN Document Server

    Ciurylo, R; Kotochigova, S; Julienne, P S

    2004-01-01

    The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between $^{1}S_{0}$ and $^{3}P_{1}$ states) of group II atoms are theoretically investigated. As an example we have carried out a calculation for Calcium atoms colliding at ultra low temperatures of 1 mK, 1 $\\mu$K, and 1 nK. Unlike in most current photoassociation spectroscopy the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using Ca--Ca and Ca--Ca$^*$ short-range {\\it ab initio} potentials and long-range van der Waals and resonance dipole potentials. The similar van der Waals coefficients of ground $^{1}S_{0} + ^{1}S_{0}$ and excited $^{1}S_{0} + ^{3}P_{1}$ states cause the PA to differ greatly from those of strong, allowed transitions with resonant dipole interactions. The density of spectral lines is lower, the Condon points are at relatively short range, and the reflection approximation for the Franck-Condon factors is not applicable, and the spontaneous ...

  20. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    Science.gov (United States)

    Singh, David Joseph

    2013-07-16

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

  1. 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.

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

    CERN Document Server

    Sahoo, B K

    2006-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

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

  4. 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.

  5. 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.

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

    Science.gov (United States)

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

    2015-09-01

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

  7. The long-range non-additive three-body dispersion interactions for the rare gases, alkali and alkaline-earth atoms

    CERN Document Server

    Tang, Li-Yan; Shi, Ting-Yun; Babb, James F; Mitroy, J

    2012-01-01

    The long-range non-additive three-body dispersion interaction coefficients $Z_{111}$, $Z_{112}$, $Z_{113}$, and $Z_{122}$ are computed for many atomic combinations using standard expressions. The atoms considered include hydrogen, the rare gases, the alkali atoms (up to Rb) and the alkaline-earth atoms (up to Sr). The term $Z_{111}$, arising from three mutual dipole interactions is known as the Axilrod-Teller-Muto coefficient or the DDD (dipole-dipole-dipole) coefficient. Similarly, the terms $Z_{112}$, $Z_{113}$, and $Z_{122}$ arise from the mutual combinations of dipole (1), quadrupole (2), and octupole (3) interactions between atoms and they are sometimes known, respectively, as DDQ, DDO, and DQQ coefficients. Results for the four $Z$ coefficients are given for the homonuclear trimers, for the trimers involving two like-rare-gas atoms, and for the trimers with all combinations of the H, He, Li atoms. An exhaustive compilation of all coefficients between all possible atomic combinations is presented as supp...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-28

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

  9. Controlled charge exchange between alkaline earth metals and their ions

    Science.gov (United States)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  10. Alkaline and alkaline earth metal phosphate halides and phosphors

    Science.gov (United States)

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

    2012-11-13

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

  11. Alkaline earth cation extraction from acid solution

    Science.gov (United States)

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

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

  12. Magic wavelengths in the alkaline earth ions

    CERN Document Server

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  14. Mixed alkaline earth effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

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

    2013-01-01

    While the mixed alkali effect has received significant attention in the glass literature, the mixed alkaline earth effect has not been thoroughly studied. Here, we investigate the latter effect by partial substitution of magnesium for calcium in sodium aluminosilicate glasses. We use Raman and NMR...... spectroscopies to obtain insights into the structural and topological features of these glasses, and hence into the mixed alkaline earth effect. We demonstrate that the mixed alkaline earth effect manifests itself as a maximum in the amount of bonded tetrahedral units and as a minimum in liquid fragility index...

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

    International Nuclear Information System (INIS)

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

  16. Surface-treatment of Alkaline Earth Sulfides Based Phosphor

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  17. Near relativistic study of bound levels in atoms. Application to alkaline atoms

    Energy Technology Data Exchange (ETDEWEB)

    Varade, A.; Delgado-Barrio, G.; Villarreal, P. (Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Estructura de la Materia)

    1985-01-01

    A model is described for the calculation of the atomic binding energies. The Pauli equation has been solved with a local potential. The results for alkaline atoms are reported here and compared with the perturbative calculation and experimental data.

  18. Solvent Extraction of Alkaline Earth Metals with Alkylphosphorus Acids

    Institute of Scientific and Technical Information of China (English)

    XUXin; ZHUTun

    2002-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    刘伟生; 温永红; 刘雪原; 谭民裕

    2003-01-01

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

  20. 40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

    Science.gov (United States)

    2010-07-01

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

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

    NARCIS (Netherlands)

    DenHartog, HW

    1996-01-01

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

  2. Modelling the crystallisation of alkaline earth boroaluminosilicate glass ceramics

    DEFF Research Database (Denmark)

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

    2014-01-01

    To investigate the potential use of a thermochemical software package (FactSage 6.2), in the design of alkaline earth boroaluminosilicate glass ceramics, experimental and modelled results on four glass ceramics were compared. Initially large discrepancies were found. These are described and related...... for the topology of multicomponent melts, before accurate prediction of phase relations within boron-containing glass ceramics can be obtained....

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

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1982-01-01

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

  4. 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.

  5. Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures.

    Science.gov (United States)

    Hu, Song; Jiang, Long; Wang, Yi; Su, Sheng; Sun, Lushi; Xu, Boyang; He, Limo; Xiang, Jun

    2015-09-01

    This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals. PMID:26005925

  6. Structural variations in layered alkaline earth metal cyclohexyl phosphonates

    Indian Academy of Sciences (India)

    Ramaswamy Murugavel; Nayanmoni Gogoi

    2009-06-01

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

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

    Institute of Scientific and Technical Information of China (English)

    YAN Kai; ZHEN Qiang; Song Xiwen

    2007-01-01

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

  8. Metal based synthetic routes to heavy alkaline earth aryloxo complexes involving ligands of moderate steric bulk.

    Science.gov (United States)

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Guino-o, Marites; Ruhlandt-Senge, Karin

    2009-07-01

    Treatment of an alkaline earth metal (Ca, Sr, Ba) with 2,4,6-trimethylphenol (HOmes) at elevated temperatures in the presence of mercury under solvent-free conditions, followed by extraction of the reaction mixture with 1,2-dimethoxyethane (dme), afforded dinuclear alkaline earth aryloxo complexes [Ae2(Omes)4(dme)4] (Ae = Ca 1, Sr 3, Ba 6). Extraction of the Ca metal and HOmes reaction mixture with thf afforded [Ca3(Omes)6(thf)] 2. In contrast, redox transmetallation ligand exchange reactions between an alkaline earth metal, diphenylmercury and HOmes in dme yielded solely 1 for Ca metal, a mixture of 3 and the methoxide bridged cage [Sr5(Omes)5(OMe)5(dme)4] x 2dme 4 for Sr metal, and solely [Ba5(Omes)5(OMe)5(dme)4] x dme 7 for Ba metal. The methoxide ligands originate from the C-O activation of the dme solvent. Treatment of liquid ammonia activated Sr or Ba metal with HOmes in thf afforded the linear species [Ae3(Omes)6(thf)6] (Ae = Sr 5, Ba 8), and 8 was also obtained from barium metal and HOmes in refluxing thf. The structures of 1 and 3, determined by X-ray crystallography, consist of two six coordinate Ae metal atoms, to each of which is bound a terminal aryloxide ligand, two bridging aryloxide ligands, and chelating and unidentate dme ligands. The structures of 4 and 7 contain five Ae metal atoms arranged on the vertices of a distorted square based pyramid. The Ae atoms are linked by four mu3-OMe ligands and a mu4-OMe ligand. Four bridging aryloxide ligands and four chelating dme ligands complete the coordination spheres of the four seven coordinate Ae atoms at the base of the pyramid, and a terminal aryloxide ligand is bound to the five coordinate apical Ae atom. The structures of 5 and 8 consist of a trinuclear linear array of Ae metal atoms, and contain solely bridging aryloxide ligands. Three thf ligands are bound to each terminal Ae atom, giving all Ae atoms a coordination number of six. PMID:19662279

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

    CERN Document Server

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

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    王玺堂; 刘浩; 王周福; 马妍

    2016-01-01

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

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

    International Nuclear Information System (INIS)

    In order to investigate the collisional processes which occur during the formation of molecular Bose-Einstein condensates, a time-independent quantum mechanical formalism, based on hyperspherical coordinates, has been applied to the study of atom-diatom dynamics at ultra-low energies. We present theoretical results for three alkali systems, each composed of lithium, sodium or potassium atoms, and for an alkaline-earth system composed of calcium atoms. We also study dynamics at large and positive atom-atom scattering length. Evidence for the suppression of inelastic processes in a fermionic system is given, as well as a linear relation between the atom-diatom scattering length and the atom-atom scattering length. (author)

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

    Science.gov (United States)

    Vasquez, R.

    1993-01-01

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

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

    OpenAIRE

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

    2010-01-01

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

  14. Laser-Induced Kondo Effect in Ultracold Alkaline-Earth Fermions.

    Science.gov (United States)

    Nakagawa, Masaya; Kawakami, Norio

    2015-10-16

    We demonstrate that laser excitations can coherently induce a novel Kondo effect in ultracold atoms in optical lattices. Using a model of alkaline-earth fermions with two orbitals, it is shown that the optically coupled two internal states are dynamically entangled to form the Kondo-singlet state, overcoming the heating effect due to the irradiation. Furthermore, a lack of SU(N) symmetry in the optical coupling provides a peculiar feature in the Kondo effect, which results in spin-selective renormalization of effective masses. We also discuss the effects of interorbital exchange interactions, and reveal that they induce novel crossover or reentrant behavior of the Kondo effect owing to control of the coupling anisotropy. The laser-induced Kondo effect is highly controllable by tuning the laser strength and the frequency, and thus offers a versatile platform to study the Kondo physics using ultracold atoms.

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

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Sven; Pernpointner, Markus, E-mail: Markus.Pernpointner@pci.uni-heidelberg.de

    2015-07-09

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

  16. IGCC sulfur compounds abatement with earth alkaline sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Ramon Alvarez-Rodriguez; Carmen Clemente-Jul [Universidad Politecnica de Madrid, Madrid (Spain). Escuela Tecnica Superior de Ingenieros de Minas

    2007-07-01

    In Integrated Gasification Combined Cycle (IGCC) process, in the reference plant built in Puertollano, Spain by Elcogas, a consortium formed by several utilities and engineering companies with a technology that is one of the most promising electricity generation options, both from the environmental and the efficiency point of view and that allows an efficient and environmentally friendly use of national coal, and also a refinery residue, petroleum coke, the high sulphur contents in coal and specially in petcoke, their presence in the feedstock, led to significant contents of gaseous sulphur compounds whose advanced removal has been the aim of this project. Different sorbents to reduce the presence of H{sub 2}S have been researched and between them the earth alkaline compounds, dolomite and calcite that react with H{sub 2}S to give calcium sulphide have been chosen due to their properties and low cost. The calcium sulphide is a reactive product because it reacts with water to regenerate the H{sub 2}S but it can be converted in calcium sulphate, inert product with diverse uses. This conversion to sulphate present some problems of possible lack of total conversion and different conditions to improve this conversion have been investigated. The tests have been carried out with dolomite and calcite and firstly the sulphuration of the same have been produced using a mixture of gases that simulates the IGCC gas and after their oxidation has been studied. The influence of the conditions of sulfurization and oxidation on the final conversion of calcium sulphide to sulphate as the presence of H{sub 2}O vapour, the variation in the composition of the gases, the temperature and the bed length have been evaluated. The solid products obtained have been characterized by X-ray diffraction and scanning electronic microscopy and chemical analysis to assess the evolution and progress of the reactions. 8 refs., 3 figs., 1 tab.

  17. Preparations of Pure Alkaline Earth Molybdate Phases from Single Molecular Precursors

    Institute of Scientific and Technical Information of China (English)

    JIANG Ya-qi; ZHAO Hong; FANG Zhi-min; WAN Hui-lin; XIONG Ming; ZHOU Zhao-hui

    2004-01-01

    The pure phases of alkaline earth molybdates MMoO4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale(<100 nm) at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 30-50 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.

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

    Science.gov (United States)

    Brandt, Sven; Pernpointner, Markus

    2015-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2001-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    范瑞溪; 狄俊伟

    1991-01-01

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

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

    Science.gov (United States)

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

    2016-03-14

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

  2. 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

  3. 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

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

    International Nuclear Information System (INIS)

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

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

    Indian Academy of Sciences (India)

    S Sreehari Sastry; B Rupa Venkateswara Rao

    2015-04-01

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

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

    Science.gov (United States)

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

    1976-01-01

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

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

    OpenAIRE

    Platero Prats, Ana Eva

    2011-01-01

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

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

    Science.gov (United States)

    Peyghan, Ali Ahmadi; Noei, Maziar

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Peyghan, Ali Ahmadi [Department of Chemistry, Faculty of Science, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Noei, Maziar, E-mail: noeimaziar@gmail.com [Department of Chemistry, Mahshahr Branch, Islamic Azad University, Mahshahr (Iran, Islamic Republic of)

    2014-01-01

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

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

    NARCIS (Netherlands)

    Xu, Jiang; Mojet, B.L.; Ommen, van J.G.; Lefferts, L.

    2004-01-01

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

  11. FORMATION (DECOMPOSITION) ENTHALPY CALCULATIONS FOR CRYSTAL LATTICES OF ALKALINE-EARTH FLUORIDES

    OpenAIRE

    Gruba, O.; Germanyuk, N.; Ryabukhin, A.

    2015-01-01

    A series of calculations of structural and thermochemical properties has been carried out for the alkaline-earth fluorides. The calculations have been carried out using the modified model of effective ionic radii and the model of enthalpy calculation for the crystal lattice. The results of the calculations are in accordance with the known experimental data within confidence intervals.

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  14. Infrared absorption of H- and D- in the alkaline-earth fluorides

    NARCIS (Netherlands)

    Jones, G. D.; Sung, J. J. Y.; Hume, T.; Ing, L. S.; Bradley, I. V.; Wells, J. P. R.

    2001-01-01

    A revisit is made to the infrared absorption spectra of H- and D- local modes in the alkaline-earth fluorides. New data on the intensity ratios of the various harmonic lines, observation of a fourth harmonic for H- in CaF2 and revised values for the anharmonic potential well constants are presented,

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  18. Optical Frequency Comb Spectroscopy of Rare Earth Atoms

    Science.gov (United States)

    Swiatlowski, Jerlyn; Palm, Christopher; Joshi, Trinity; Montcrieffe, Caitlin; Jackson Kimball, Derek

    2013-05-01

    We discuss progress in our experimental program to employ optical-frequency-comb-based spectroscopy to understand the complex spectra of rare-earth atoms. We plan to carry out systematic measurements of atomic transitions in rare-earth atoms to elucidate the energy level structure and term assignment and determine presently unknown atomic state parameters. This spectroscopic information is important in view of the increasing interest in rare-earth atoms for atomic frequency standards, in astrophysical investigations of chemically peculiar stars, and in tests of fundamental physics (tests of parity and time-reversal invariance, searches for time variation of fundamental constants, etc.). We are presently studying the use of hollow cathode lamps as atomic sources for two-photon frequency comb spectroscopy. Supported by the National Science Foundation under grant PHY-0958749.

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2012-05-01

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

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

    Science.gov (United States)

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

    2016-03-18

    Alkaline-earth (Ae=Ca, Sr, Ba) complexes are shown to catalyse the chemoselective cross-dehydrocoupling (CDC) of amines and hydrosilanes. Key trends were delineated in the benchmark couplings of Ph3 SiH with pyrrolidine or tBuNH2 . Ae{E(SiMe3)2}2 ⋅(THF)x (E=N, CH; x=2-3) are more efficient than {N^N}Ae{E(SiMe3)2}⋅(THF)n (E=N, CH; n=1-2) complexes (where {N^N}(-) ={ArN(o-C6H4)C(H)=NAr}(-) with Ar=2,6-iPr2 -C6H3) bearing an iminoanilide ligand, and alkyl precatalysts are better than amido analogues. Turnover frequencies (TOFs) increase in the order Ca30 products) includes diamines and di(hydrosilane)s. Kinetic analysis of the Ba-promoted CDC of pyrrolidine and Ph3SiH shows that 1) the kinetic law is rate=k[Ba](1) [amine](0) [hydrosilane](1), 2) electron-withdrawing p-substituents on the arylhydrosilane improve the reaction rate and 3) a maximal kinetic isotopic effect (kSiH/kSiD =4.7) is seen for Ph3SiX (X=H, D). DFT calculations identified the prevailing mechanism; instead of an inaccessible σ-bond-breaking metathesis pathway, the CDC appears to follow a stepwise reaction path with N-Si bond-forming nucleophilic attack of the catalytically competent Ba pyrrolide onto the incoming silane, followed by rate limiting hydrogen-atom transfer to barium. The participation of a Ba silyl species is prevented energetically. The reactivity trend Cametal centre and decreasing Ae-Namide bond strength upon descending Group 2. PMID:26864122

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

    Science.gov (United States)

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

    2016-03-18

    Alkaline-earth (Ae=Ca, Sr, Ba) complexes are shown to catalyse the chemoselective cross-dehydrocoupling (CDC) of amines and hydrosilanes. Key trends were delineated in the benchmark couplings of Ph3 SiH with pyrrolidine or tBuNH2 . Ae{E(SiMe3)2}2 ⋅(THF)x (E=N, CH; x=2-3) are more efficient than {N^N}Ae{E(SiMe3)2}⋅(THF)n (E=N, CH; n=1-2) complexes (where {N^N}(-) ={ArN(o-C6H4)C(H)=NAr}(-) with Ar=2,6-iPr2 -C6H3) bearing an iminoanilide ligand, and alkyl precatalysts are better than amido analogues. Turnover frequencies (TOFs) increase in the order Ca30 products) includes diamines and di(hydrosilane)s. Kinetic analysis of the Ba-promoted CDC of pyrrolidine and Ph3SiH shows that 1) the kinetic law is rate=k[Ba](1) [amine](0) [hydrosilane](1), 2) electron-withdrawing p-substituents on the arylhydrosilane improve the reaction rate and 3) a maximal kinetic isotopic effect (kSiH/kSiD =4.7) is seen for Ph3SiX (X=H, D). DFT calculations identified the prevailing mechanism; instead of an inaccessible σ-bond-breaking metathesis pathway, the CDC appears to follow a stepwise reaction path with N-Si bond-forming nucleophilic attack of the catalytically competent Ba pyrrolide onto the incoming silane, followed by rate limiting hydrogen-atom transfer to barium. The participation of a Ba silyl species is prevented energetically. The reactivity trend Cametal centre and decreasing Ae-Namide bond strength upon descending Group 2.

  3. Noble gas, alkali and alkaline atoms interacting with a gold surface

    CERN Document Server

    Łach, Grzegorz; Jentschura, Ulrich D; 10.1142/S0217751X1004961X

    2013-01-01

    The attractive branch of the interaction potentials with the surface of gold have been computed for a large variety of atomic systems: the hydrogen atom, noble gases (He, Ne, Ar, Kr, Xe), alkali atoms (Li, Na, K, Rb, Cs) and alkaline atoms (Be, Mg, Ca, Sr, Ba). The results include highly accurate dynamic polarizabilities for the helium atom calculated using a variational method and explicitly correlated wavefunctions. For other atoms considered we used the data available in the literature. The interaction potentials include both the effects of retardation of the electromagnetic interactions and a realistic representation of the optical response function of gold (beyond the approximation of a perfect conductor). An explicit comparison of our result to the interaction between an atom and a perfect conductor is given.

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

    Indian Academy of Sciences (India)

    J K Baria; A R Jani

    2010-10-01

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

  5. Solvation structures and dynamics of alkaline earth metal halides in supercritical water: A molecular dynamics study

    Science.gov (United States)

    Keshri, Sonanki; Mandal, Ratnamala; Tembe, B. L.

    2016-09-01

    Constrained molecular dynamics simulations of alkaline earth metal halides have been carried out to investigate their structural and dynamical properties in supercritical water. Potentials of mean force (PMFs) for all the alkaline earth metal halides in supercritical water have been computed. Contact ion pairs (CIPs) are found to be more stable than all other configurations of the ion pairs except for MgI2 where solvent shared ion pair (SShIP) is more stable than the CIP. There is hardly any difference in the PMFs between the M2+ (M = Mg, Ca, Sr, Ba) and the X- (X = F, Cl, Br, I) ions whether the second X- ion is present in the first coordination shell of the M2+ ion or not. The solvent molecules in the solvation shells diffuse at a much slower rate compared to the bulk. Orientational distribution functions of solvent molecules are sharper for smaller ions.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    show that the mixed alkaline earth effect manifests itself as deviations from linearity in shear modulus, Poisson’s ratio, glass transition temperature, liquid fragility index, hardness, volume of densification, and volume of plastic flow. We find no correlation between the elastic part...... of the indentation and hardness, and we thus infer that elastic deformation does not play a dominant role in determining the mixed alkaline earth effect of hardness. However, interestingly, we find a strong correlation between Poisson’s ratio, volume of plastic flow, and hardness, by which the minimum in hardness......Glasses deform permanently as a result of indentation and the total resistance to deformation consists of three individual resistances, i.e., those to elastic deformation, densification, and plastic flow. The link between Vickers hardness and the resistances to densification and plastic flow has...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    The influence of relative humidity on microhardness, stress intensity, crack resistance, and sub-critical crack growth of an alkaline earth aluminosilicate glass has been studied by Vickers indentation. Quenched and annealed glasses with a wide range of fictive temperatures (ΔTf ≈ 130 K) are comp......The influence of relative humidity on microhardness, stress intensity, crack resistance, and sub-critical crack growth of an alkaline earth aluminosilicate glass has been studied by Vickers indentation. Quenched and annealed glasses with a wide range of fictive temperatures (ΔTf ≈ 130 K......) are compared in order to determine the influence of the thermal history on these properties. Vickers hardness is found to be essentially unaffected by the environmental conditions, while the stress intensity factor (fracture toughness) and the crack resistance decrease significantly with increasing humidity...

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

    Science.gov (United States)

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

    2000-12-01

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

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

    OpenAIRE

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

    2012-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-01

    In this paper spectroscopic investigation of Cu{sup 2+} doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu{sup 2+} state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu{sup 2+} is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds.

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

    Science.gov (United States)

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

    2014-02-01

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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Chattopadhyay, S; Angom, D

    2013-01-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    Science.gov (United States)

    Radzhabov, E.

    2002-06-01

    Defects in Ce 3+- and Eu 2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF 2:Eu 2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce 3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF 2:Ce 3+ and SrF 2:Ce 3+ crystals. Creation of Ce 2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce 3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce 2+ or Eu + ions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Radzhabov, E.; Nepomnyaschikh, A.

    2012-01-01

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

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

    Science.gov (United States)

    Mousa, Haider Abdul-Lateef

    2016-04-01

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

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

    Science.gov (United States)

    Mousa, Haider Abdul-Lateef

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-04-25

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Wolfgang

    2008-03-19

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

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

    Science.gov (United States)

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

    2014-06-01

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

  9. Lifshitz and other transitions in alkaline-earth 122 pnictides under pressure

    Science.gov (United States)

    Quader, Khandker; Widom, Michael

    2014-10-01

    We carry out T =0 first-principles total energy calculations in the entire set of alkaline 122-pnictides (A Fe2As2 ; A = alkaline-earth element Ca, Sr, Ba, Ra) as a function of hydrostatic pressure. We find multiple distinct transitions to occur, namely an enthalpic transition in which the zero-pressure striped antiferromagnetic orthorhombic (OR-AFM) phase becomes thermodynamically less stable than a competing tetragonal (T) phase, a magnetic transition in which the OR-AFM phase loses its magnetism and orthorhombicity, and a lattice parameter anomaly in which the tetragonal c-axis collapses and a collapsed tetragonal (cT) phase becomes stable. Our results for energy band dispersions and spectra, lattice parameters, enthalpies, magnetism, and elastic constants over a wide range of hydrostatic pressure provide a coherent understanding of these experimentally observed transitions. In particular, the T-cT transition and anomalies in lattice parameters and elastic properties, observed at finite temperatures, are interpreted as arising from proximity to T =0 Lifshitz transitions, wherein pressure causes nontrivial changes in the Fermi surface topology in these materials.

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

    Science.gov (United States)

    González, Miriam Ferrer; Ilyina, Tatiana

    2016-06-01

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

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

    Science.gov (United States)

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

    1986-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Quemener, G

    2006-10-15

    In order to investigate the collisional processes which occur during the formation of molecular Bose-Einstein condensates, a time-independent quantum mechanical formalism, based on hyperspherical coordinates, has been applied to the study of atom-diatom dynamics at ultra-low energies. We present theoretical results for three alkali systems, each composed of lithium, sodium or potassium atoms, and for an alkaline-earth system composed of calcium atoms. We also study dynamics at large and positive atom-atom scattering length. Evidence for the suppression of inelastic processes in a fermionic system is given, as well as a linear relation between the atom-diatom scattering length and the atom-atom scattering length. (author)

  13. Earth sciences. 1990-2001. International Atomic Energy Agency publications

    International Nuclear Information System (INIS)

    This catalogue lists all sales publications of the International Atomic Energy Agency dealing with Earth Sciences and issued during the period 1 January 1990 - 31 May 2001. Most publications are issued in English, though some are also available in other languages. This is noted as A for Arabic, C for Chinese, E for English, F for French, R for Russian and S for Spanish before the relevant ISBN number

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

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

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

    Science.gov (United States)

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

    2016-10-01

    Combination of hexakis(4-carboxylatephenoxy)cyclotriphosphazene with alkaline earth ions of increasing ionic radii (Mg2+, Ca2+ and Ba2+) under different solvothermal conditions yielded three new coordination polymers, and their crystal structures were determined by single-crystal X-ray diffraction analysis. The magnesium compound displays a three dimensional (3D) network structure constructed from the deprotonated ligand and the secondary building block Mg(COO)4, which can be rationalized as a (4,6)-connected topological net with the Schläfli symbol of (44·62)3(49·66)2. The calcium compound consists of 1D infinite "Ca-O" inorganic chains connected by the deprotonated ligands to from a 3D framework. The barium compound exhibits a 3D framework in which 1D "Ba-O" inorganic chains are connected together by the deprotonated organic linkers. Due to the semi-rigid nature, the ligand adopts distinctly different conformations in the three compounds. The metal ions' influence exerted on the final structure of the resulting coordination polymers is also discussed. When the radii of alkaline earth ions increases descending down the group from Mg(II) to Ba(II), the coordination number becomes larger and more versatile: from 6 in the magnesium compound, to 6,7 and 10 in the calcium compound, and to 8 and 9 in the barium compound, thus substantially influencing the resulting final framework structures. Also, the photophysical properties were investigated systematically, revealing that the three compounds are photoluminscent in the solid state at room temperature. This work demonstrates that although the multiplicity of conformation in the hexacarboxylate ligand based on the inorganic scaffold cyclotriphosphazene makes it difficult to predict how this ligand will form extended network, but provides unique opportunities for the formation of diverse inorganic-organic hybrids exhibiting rich structural topologies.

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

    Directory of Open Access Journals (Sweden)

    Doory Kim

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

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

    Science.gov (United States)

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

    2016-01-01

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

  18. Electronic structures and second hyperpolarizabilities of alkaline earth metal complexes end-capped with NA2 (A = H, Li, Na).

    Science.gov (United States)

    Banerjee, Paramita; Nandi, Prasanta K

    2016-05-14

    The ground state structures and NLO properties of a number of alkaline earth metal complexes end-capped with NA2 groups (A = H, Li, Na) are calculated by employing the CAM-B3LYP, wB97XD and B2PLYP functionals along with MP2 and CCSD(T) for 6-311++G(d,p), 6-311++G(3df,3pd), aug-cc-pVTZ, aug-pc-2 and Hypol basis sets. The complexes are found to be significantly stable. The magnitude of second hyperpolarizability enhances appreciably with increase in the number of magnesium and calcium atoms in the chain, which has been indicated by the power law dependence γ = a + bn(c) with c values ranging from 2.4-4.3 for Mg and 2.4-3.7 for Ca complexes, respectively. The largest second-hyperpolarizability (10(9) au) is obtained for the complex Ca7(NNa2)2 at the CAM-B3LYP level. The two state model has been used to explain the variation of hyperpolarizabilities. PMID:27088138

  19. A preorganized metalloreceptor for alkaline earth ions showing calcium versus magnesium selectivity in water: biological activity of selected metal complexes.

    Science.gov (United States)

    Amatori, Stefano; Ambrosi, Gianluca; Fanelli, Mirco; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Rossi, Patrizia

    2014-08-25

    The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (Malten = L) forms the highly stable [CuH(-2)L] species in water, in which the converging maltol oxygen atoms form an electron-rich area able to host hard metal ions. When considering the alkaline earth series (AE), the [Cu(H(-2)L)] species binds all metal ions, with the exception of Mg(2+), exhibiting the relevant property to discriminate Ca(2+) versus Mg(2+) at physiological pH 7.4; the binding of the AE metal is visible to the naked eye. The stability constant values of the trinuclear [AE{Cu(H(-2)L)}2](2+) species formed reach the maximum for Ca(2+) (log K=7.7). Ca(2+) also forms a tetranuclear [Ca{Cu(H(-2)L)}]2(4+) species at a high Ca(2+) concentration. Tri- and tetranuclear calcium complexes show blue- and pink-colored crystals, respectively. [Cu(H(-2)L)] is the most active species in inducing DNA alterations. The DNA damages are compatible with its hydrolytic cleavages.

  20. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides

    NARCIS (Netherlands)

    Hereijgers, B.P.C.; Weckhuysen, B.M.

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with al

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

    Science.gov (United States)

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

    2012-03-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  3. Earth sciences 1980-1994. International Atomic Energy Agency Publications

    International Nuclear Information System (INIS)

    This catalogue lists sales publications of the International Atomic Energy Agency dealing with Earth Sciences issued during the period 1969-1994. Most publications are published in English. Proceedings of conferences, symposia and panels of experts may contain some papers in languages other than English (French, Russian or Spanish), but all these papers have abstracts in English. It should be noted that prices of books are quoted in Austrian Schillings. The prices do not include local taxes and are subject to change without notice. All books in this catalogue are 16 x 24 cm, paper-bound, unless otherwise stated

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

    International Nuclear Information System (INIS)

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

  5. Syntheses, structure and properties of Alkaline-earth metal salts of 4-Nitrophenylacetic acid

    Indian Academy of Sciences (India)

    BIKSHANDARKOIL R SRINIVASAN; KIRAN T DHAVSKAR; CHRISTIAN NÄTHER

    2016-11-01

    The synthesis, crystal structure, spectral characteristics and thermal properties of alkaline-earth metal salts of 4-nitrophenylacetic acid (4-npaH) namely, [Mg(H₂O)₆](4-npa)₂·4H₂O (4-npa = 4-nitrophenylacetate) (1), [Ca(H₂O)₂(4-npa)₂] (2) and [Sr(H₂O)₃(4-npa)₂]·4.5H₂O(3) are reported. In 1, the 4-npa ion functions as a charge balancing counter anion for the octahedral [Mg(H₂O)6]²⁺ unit with the Mg(II) ion situated on a centre of inversion. The two unique lattice water molecules link the [Mg(H₂O)₆]²⁺ cations and 4-npa anions with the aid of O-H· · ·O interactions. Compounds 2 and 3 are one-dimensional (1-D) coordination polymers containing an eight coordinated Ca(II) situated in a general position and a nine coordinated Sr(II) located on a twofold axis. The μ₂-bridging tridentate binding modes of the crystallographically independent 4-npa ligands in 2 and the unique 4-npa ligand in 3 link the bivalent metal ions into an infinite chain with alternating Ca· · · Ca separations of 3.989 and 4.009 Å, respectively, and a single Sr· · · Sr separation of 4.194Å in the 1-D chain.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-15

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

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

    Indian Academy of Sciences (India)

    Angelos G Kalampounias

    2011-04-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  10. 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.

  11. Rare earth aerosol analysis by atomic absorption spectrophotometry using electrothermal atomization

    International Nuclear Information System (INIS)

    Atomic absorption spectrophotometry (AAS) employing electrothermal atomization in a pyrolytic graphite tube is shown to be a precise and accurate method for analysis of 11 rare earth, or rare-earth-like elements in air filter samples taken in a thorium and rare earth refinery. The method is fairly rapid since it involves only fluoric acids. Each element was sequentially analyzed from the same resulting solution by using either the techniques of standard-curve calibration or that of standard additions. The two methods used on the same sample gave essentially identical results (composite ratio for 171 such trials being 0.9996). Matrix effects were negligible and no background correction was necessary. The average percent standard deviation for all duplicate trials (176) was 4.2%. Elements analyzed by this method were La, Nd, Sm, Eu, Gd, Dy, Ho, Tm, Yb, Gd, Sc and Y. Other rare earths such as erbium (Er), lutetium (Lu), and terbium (Tb), with comparable analytical sensitivity by AAS to Dy, Sm, and Nd, respectively, could presumably be analyzed by this method as well

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-01

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

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

    International Nuclear Information System (INIS)

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

  14. Investigation on Alkaline-Earth Houses in Jilin Province%吉林碱土民居考察

    Institute of Scientific and Technical Information of China (English)

    王红燕; 朴玉顺

    2012-01-01

    Through extensive research on the residential alkali soil houses in places of the of Yilibao, Sanli bad in the Daan Town,the New Peace Town and Anguang Town, the article clears the distribution and characteristics of the Jilin province alkaline earth houses. Through the residents of the area of alkali land survey- ing and mapping field exploration and focus, the article summarizes the status of the use of alkaline-earth res- idence and makes a detailed analysis of characteristics of alkaline-earth residence. These characteristics are as follows:the alkaline-earth residents living with the ease of local materials, low cost, good thermal insulation properties ,cool, short lifetime, difficult to maintain ,easily damaged and unsightly appearance.%通过对吉林省大安市平安镇一里堡、三里堡、新平安镇、安广镇等地的碱土民居的广泛调研,厘清了吉林省境内碱土民居的分布规律和特点。通过对该地区碱土民居的实地踏勘和重点测绘,总结归纳了碱土民居的使用现状,详细剖析了碱土民居所具有的便于就地取材、造价低廉,保温隔热性能好、冬暖夏凉,使用寿命短、维护困难,易受损、外观不美观等特点。

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

    OpenAIRE

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

    2004-01-01

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

  16. Halogen-abstraction reactions from chloromethane and bromomethane molecules by alkaline-earth monocations.

    Science.gov (United States)

    Redondo, Pilar; Largo, Antonio; Rayón, Víctor Manuel; Molpeceres, Germán; Sordo, José Ángel; Barrientos, Carmen

    2014-08-14

    The reactions, in the gas phase, between alkali-earth monocations (Mg(+), Ca(+), Sr(+), Ba(+)) and CH3X (X = Cl, Br) have been theoretically studied. The stationary points on the potential energy surfaces were characterized at the Density Functional Theory level on the framework of the mPW1K functional with the QZVPP Ahlrichs's basis sets. A complementary kinetics study has also been performed using conventional/variational microcanonical transition state theory. In the reactions of Mg(+) with either chloro- or bromomethane the transition structure lies in energy clearly above the reactants rendering thermal activation of CH3Cl or CH3Br extremely improbable. The remaining reactions are exothermic and barrierless processes; thus carbon-halogen bonds in chloro- or bromomethane can be activated by calcium, strontium or barium monocations to obtain the metal halogen cation and the methyl radical. The Mulliken population analysis for the stationary points of the potential energy surfaces supports a "harpoon"-like mechanism for the halogen-atom abstraction processes. An analysis of the bonding situation for the stationary points on the potential energy surface has also been performed in the framework of the quantum theory of atoms in molecules.

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

    Science.gov (United States)

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

    2016-09-21

    a modified mechanism for group 2-mediated dimethylamine borane dehydrocoupling that is dependent on the intermediacy of key derivatives of the [NMe2·BH3](-) and [NMe2BH2NMe2BH3](-) anions but does not require the formation of high energy alkaline earth hydride intermediates. Although these results are specifically focussed on the applications of alkaline earth species, this mechanistic insight may also be relevant to other redox-inactive main group element-based systems and to our understanding of hydrogen evolution from saline derivatives of ammonia borane. PMID:27529536

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

    Science.gov (United States)

    Gonzalez, M. F.; Ilyina, T.

    2014-12-01

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

  19. Electron emission of alkaline and alkaline-earth vapors adsorbed on refractory metals; Emission electronique des metaux alcalins et alcalino-terreux adsorbes sur les metaux refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Alleau, Th.; Desplat, J.L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    This work has been carried out as an aid to research on thermionic converter electrodes. The improvement of the converter efficiency makes it necessary to explain physically the adsorption process, and to determine theoretically its laws. The Gyftopoulos, Levine, Steiner's latest theory has been used to plot, by means of a computer, the 'S' shaped curves which bind the electron emission of adsorbed alkaline and alkaline-earth metals to their temperature and to the substrate temperature. 21 examples are presented, some of them being studied with crystallographic orientation. (authors) [French] Cette etude a ete realisee dans le cadre des recherches effectuees sur les electrodes des convertisseurs thermoioniques. L'explication physique des phenomenes d'adsorption et la connaissance theorique de leurs lois, est indispensable a l'amelioration du rendement des convertisseurs. Il a ete fait appel a la recente theorie de E.P. Gyftopoulos, J.D. Levine, D. Steiner pour tracer par ordinateur les courbes en 'S' qui lient l'emission electronique des metaux alcalins ou alcalino-terreux a leur temperature et a la temperature des metaux refractaires sur lesquels ils sont adsorbes. 21 cas sont etudies, dont certains en fonction de l'orientation cristalline. (auteurs)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-05

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

  1. Construction of embedded-atom-method interatomic potentials for alkaline metals (Li, Na, and K) by lattice inversion

    Institute of Scientific and Technical Information of China (English)

    Yuan Xiao-Jian; Chen Nan-Xian; Shen Jiang

    2012-01-01

    The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li,Na,and K.It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials,especially for the prediction of surface energy.The lattice-inversion embedded-atom-method interatomic potentials for Li,Na,and K are successfully constructed by taking the fourth-neighbor atoms into consideration.These angular-independent potentials markedly promote the accuracy of predicted surface energies,which agree well with experimental results.In addition,the predicted structural stability,elastic constants,formation and migration energies of vacancy,and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations,and the equilibrium condition is satisfied.

  2. The MCVD synthesis and characterization of water tolerant fiber optic waveguides based on alkaline earth-doped silicas

    Science.gov (United States)

    Farley, Kevin F.

    Optical fibers that transmit throughout the entire telecommunications spectrum (1.2--1.7 mum) are presently manufactured by the removal of hydrogen or OH from the host preform glass. Hydrogen-oxygen torches are utilized in the conventional preform manufacturing process, but result in the formation of hydroxyls in germanium-doped silica fiber. The hydroxyl species generate unacceptably high losses for long haul telecommunications systems. This thesis has explored an alternative strategy for reducing OH-related absorption in silica-based glasses. Alkaline earth modifiers have been introduced via the modified chemical vapor deposition (MCVD) process to successfully damp out and dramatically reduce the extrinsic attenuation associated with both water and hydrogen. Specifically, alkaline earth ions were introduced into alumino-silicate glasses to form MgO-Al2O3-SiO2, CaO-Al 2O3-SiO2, and SrO-Al2O3-SiO 2 compositions. The utilization of halide precursors based on the vapor delivery of rare earths was incorporated into the existing MCVD set-up to fabricate these optical preforms. Both the bulk preforms and fibers drawn from them were characterized to determine relevant optical properties, including the attenuation, index profiles and extinction coefficients arising from OH in each host. The data indicate that modification of the silica glass structure through the additions of modifying ions can significantly reduce OH related absorption. For example, the doping of alkaline earth ions decreased the extinction coefficient measured at the 1.39 mum) OH overtone, to values reinforced by a series of experiments documenting their resistance to hydrogen induced losses.

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

    Science.gov (United States)

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

    2015-05-01

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

  4. Eocene seasonality and seawater alkaline earth reconstruction using shallow-dwelling large benthic foraminifera

    Science.gov (United States)

    Evans, David; Müller, Wolfgang; Oron, Shai; Renema, Willem

    2013-11-01

    Intra-test variability in Mg/Ca and other (trace) elements within large benthic foraminifera (LBF) of the family Nummulitidae have been investigated using laser-ablation inductively-coupled plasma mass spectrometry (LA-ICPMS). These foraminifera have a longevity and size facilitating seasonal proxy retrieval and a depth distribution similar to 'surface-dwelling' planktic foraminifera. Coupled with their abundance in climatically important periods such as the Paleogene, this means that this family of foraminifera are an important but under-utilised source of palaeoclimatic information. We have calibrated the relationship between Mg/Ca and temperature in modern Operculina ammonoides and observe a ˜2% increase in Mg/Ca °C-1. O. ammonoides is the nearest living relative of the abundant Eocene genus Nummulites, enabling us to reconstruct mid-Eocene tropical sea surface temperature seasonality by applying our calibration to fossil Nummulites djokdjokartae from Java. Our results indicate a 5-6 °C annual temperature range, implying greater than modern seasonality in the mid-Eocene (Bartonian). This is consistent with seasonal surface ocean cooling facilitated by enhanced Eocene tropical cyclone-induced upper ocean mixing, as suggested by recent modelling results. Analyses of fossil N. djokdjokartae and Operculina sp. from the same stratigraphic interval demonstrate that environmental controls on proxy distribution coefficients are the same for these two genera, within error. Using previously published test-seawater alkaline earth metal distribution coefficients derived from an LBF of the same family (Raitzsch et al., 2010) and inorganic calcite, with appropriate correction systematics for secular Mg/Casw variation (Evans and Müller, 2012), we use our fossil data to produce a more accurate foraminifera-based Mg/Casw reconstruction and an estimate of seawater Sr/Ca. We demonstrate that mid-Eocene Mg/Casw was ≲2 molmol, which is in contrast to the model most

  5. Rare earth analysis in human biological samples by atomic absorption using electrothermal atomization

    International Nuclear Information System (INIS)

    The determination of Sc and seven rare earth elements, Nd, Sm, Dy, Ho, Eu, Tm, and Yb, in biological samplesby atomic absorption spectrophotometric analysis (AAS) using electrothermal atomization in a pyrolytic graphite tube is shown to be rapid, precise and accurate. The technique utilizes the method of standard additions and linear regression analysis to determine results from peak area data. Inter-elemental interferences are negligible. The elements found sensitive enough for this type of analysis are, in order of decreasing sensitivity, Yb, Eu, Tm, Dy, Sc, Ho, Sm and Nd. The determination in these types of materials of Gd and elements less sensitive to AAS detection than Gd does not appear to be feasible. Results are presented on the concentrations of these elements in 41 samples from human subjects, cows and vegetables with normal environmental exposure to the rare earth elements. The composite percent mean deviation in peak-area readings for all samples and all elements examined was 4%. The mean standard error in the results among samples was about 6.5%

  6. The influence of alkaline earth metal equilibria on the rheological, melting and textural properties of Cheddar cheese.

    Science.gov (United States)

    Cooke, Darren R; McSweeney, Paul L H

    2013-11-01

    The total calcium content of cheese, along with changes in the equilibrium between soluble and casein (CN)-bound calcium during ripening can have a major impact on its rheological, functional and textural properties; however, little is known about the effect of other alkaline earth metals. NaCl was partially substituted with MgCl2 or SrCl2 (8·7 and 11·4 g/kg curd, respectively) at the salting stage of cheesemaking to study their effects on cheese. Three cheeses were produced: Mg supplemented (+Mg), Sr supplemented (+Sr) and a control Cheddar cheese. Ca, Mg and Sr contents of cheese and expressible serum obtained therefrom were determined by atomic absorption spectroscopy. Addition of Mg2+ or Sr2+ had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg2+ and Sr2+ became CN-bound. The level of CN-bound Mg was higher in the +Mg cheese than the control throughout ripening. The level of CN-bound Ca and Mg decreased during ripening in all cheeses, as did % CN-bound Sr in the +Sr cheese. The presence of Sr2+ increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg2+ had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher G' at 70 °C and a lower LTmax than the control and +Mg cheeses throughout ripening. The +Sr cheese had significantly lower meltability compared with the control and +Mg cheeses after 2 months of ripening. Hardness values of the +Sr cheese were higher at week 2 than the +Mg and control cheeses. Addition of Mg2+ did not influence the physical properties of cheese. Supplementing cheese with Sr appeared to have effects analogous to those previously reported for increasing Ca content. Sr2+ may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Zhou, Qiang; Qian, Jun; Zhang, Chi

    2016-09-01

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

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

    International Nuclear Information System (INIS)

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

  12. Operation of the computer model for direct atomic oxygen exposure of Earth satellites

    Science.gov (United States)

    Bourassa, R. J.; Gruenbaum, P. E.; Gillis, J. R.; Hargraves, C. R.

    1995-01-01

    One of the primary causes of material degradation in low Earth orbit (LEO) is exposure to atomic oxygen. When atomic oxygen molecules collide with an orbiting spacecraft, the relative velocity is 7 to 8 km/sec and the collision energy is 4 to 5 eV per atom. Under these conditions, atomic oxygen may initiate a number of chemical and physical reactions with exposed materials. These reactions contribute to material degradation, surface erosion, and contamination. Interpretation of these effects on materials and the design of space hardware to withstand on-orbit conditions requires quantitative knowledge of the atomic oxygen exposure environment. Atomic oxygen flux is a function of orbit altitude, the orientation of the orbit plan to the Sun, solar and geomagnetic activity, and the angle between exposed surfaces and the spacecraft heading. We have developed a computer model to predict the atomic oxygen exposure of spacecraft in low Earth orbit. The application of this computer model is discussed.

  13. Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

    Science.gov (United States)

    Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

    2013-11-21

    NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times. PMID:24096887

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

    Directory of Open Access Journals (Sweden)

    David Parker and David J Singh

    2013-01-01

    Full Text Available We present a detailed theoretical study of three alkaline earth compounds Ca2Pb, Sr2Pb and Ba2Pb, which have undergone little previous study, calculating electronic band structures and Boltzmann transport and bulk moduli using density functional theory. We also study the corresponding tin compounds Ca2Sn, Sr2Sn and Ba2Sn. We find that these are all narrow band gap semiconductors with an electronic structure favorable for thermoelectric performance, with substantial thermopowers for the lead compounds at temperature ranges from 300 to 800 K. For the lead compounds, we further find very low calculated bulk moduli—roughly half of the values for the lead chalcogenides, suggestive of soft phonons and hence low lattice thermal conductivity. All these facts indicate that these materials merit experimental investigation as potential high performance thermoelectrics. We find good potential for thermoelectric performance in the environmentally friendly stannide materials, particularly at high temperature.

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

    Science.gov (United States)

    Iskin, M.

    2016-07-01

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

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

    Indian Academy of Sciences (India)

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

    2014-09-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, J., E-mail: fguillen@unex.es [LARUEX, Dpt. Applied Physics, Faculty of Veterinary Science, University of Extremadura, Avda. Universidad, s/n, 10071 Caceres (Spain); Baeza, A.; Salas, A. [LARUEX, Dpt. Applied Physics, Faculty of Veterinary Science, University of Extremadura, Avda. Universidad, s/n, 10071 Caceres (Spain)

    2012-04-15

    In the literature, there are many data available on radionuclide contents and their transfer to different species of mushrooms. There are some variables, however, which affect the transfer but are very difficult to observe in collected wild mushrooms. An example is the effect of different concentrations of alkali and alkaline earth elements in the soil. Modification of these concentrations in the soil solution has traditionally been used as a countermeasure to deal with radioactively contaminated areas. In the present work, fruiting bodies of Pleurotus eryngii, a saprophytic mushroom, were grown under controlled laboratory conditions, varying the content of alkali (potassium and caesium) and alkaline earth (calcium and strontium) elements. The transfer of {sup 134}Cs, {sup 85}Sr, and {sup 60}Co (added to the cultures) and of natural {sup 210}Pb was analysed by increasing the content of each stable element considered. A significant, but nonlinear, enhancement of stable caesium and {sup 134}Cs was observed with increasing content of stable caesium in the substrate/mycelium. The transfer of {sup 85}Sr decreased with the addition of each stable cation, whereas the {sup 60}Co and {sup 210}Pb transfers were unaffected. - Highlights: Black-Right-Pointing-Pointer The addition of stable potassium did not affect the uptake of radiocaesium. Black-Right-Pointing-Pointer The addition of stable caesium increased the stable caesium and {sup 134}Cs content in the fruiting bodies of Pleurotus eryngii. Black-Right-Pointing-Pointer The addition of calcium reduced the content of calcium and {sup 85}Sr in the fruiting bodies. Black-Right-Pointing-Pointer These countermeasures did not work properly in the case of {sup 60}Co and {sup 210}Pb, no effect was observed.

  19. Characterization of alkaline-earth oxide additions to the MnO2 cathode in an aqueous secondary battery

    International Nuclear Information System (INIS)

    Highlights: → Adding MgO in MnO2 cathode enhances the battery discharge capacity. → Mechanism appears to be different with those of our previously published results. → Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. → Transferred the primary battery into a secondary while using LiOH as electrolyte. - Abstract: The effect of alkaline-earth oxide additions on aqueous rechargeable battery is investigated using microscopic and spectroscopic techniques. The alkaline-earth oxide additions such as magnesium oxide (MgO) and barium oxide (BaO) were physically mixed to the manganese dioxide (MnO2) cathode of a cell comprising zinc as an anode and aqueous lithium hydroxide as the electrolyte. The results showed that such additions greatly improved the discharge capacity of the battery (from 145 to 195 for MgO and 265 mAh/g for BaO). Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. With an aim to understand the role of these additives and its improvement in cell performance, we have used microscopy, spectroscopy, ion beam analysis and diffraction based techniques to study the process. Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy analysis (EDS) results showed evidence of crystalline MnO2 particles for MgO as additive, whereas, MnO2 particles with diffused structure leading to mixture of phases is observed for BaO additives which is in agreement with X-ray diffraction (XRD) data. This work relates to improvement in the electrochemical behaviour of the Zn-MnO2 battery while the MgO additive helps to reduce the formation of manganese and zinc such as hetaerolite that hinders the lithium intercalation.

  20. Characterization of alkaline-earth oxide additions to the MnO{sub 2} cathode in an aqueous secondary battery

    Energy Technology Data Exchange (ETDEWEB)

    Minakshi, Manickam, E-mail: minakshi@murdoch.edu.au [Extractive Metallurgy, Murdoch University, Murdoch, WA 6150 (Australia); Blackford, Mark [Institute of Materials Engineering, ANSTO, Lucas Heights, NSW 2234 (Australia); Ionescu, Mihail [Institute for Environment Research, ANSTO, Lucas Heights, NSW 2234 (Australia)

    2011-05-19

    Highlights: > Adding MgO in MnO{sub 2} cathode enhances the battery discharge capacity. > Mechanism appears to be different with those of our previously published results. > Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. > Transferred the primary battery into a secondary while using LiOH as electrolyte. - Abstract: The effect of alkaline-earth oxide additions on aqueous rechargeable battery is investigated using microscopic and spectroscopic techniques. The alkaline-earth oxide additions such as magnesium oxide (MgO) and barium oxide (BaO) were physically mixed to the manganese dioxide (MnO{sub 2}) cathode of a cell comprising zinc as an anode and aqueous lithium hydroxide as the electrolyte. The results showed that such additions greatly improved the discharge capacity of the battery (from 145 to 195 for MgO and 265 mAh/g for BaO). Capacity fade with subsequent cycling is reduced only for MgO but not for BaO. With an aim to understand the role of these additives and its improvement in cell performance, we have used microscopy, spectroscopy, ion beam analysis and diffraction based techniques to study the process. Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy analysis (EDS) results showed evidence of crystalline MnO{sub 2} particles for MgO as additive, whereas, MnO{sub 2} particles with diffused structure leading to mixture of phases is observed for BaO additives which is in agreement with X-ray diffraction (XRD) data. This work relates to improvement in the electrochemical behaviour of the Zn-MnO{sub 2} battery while the MgO additive helps to reduce the formation of manganese and zinc such as hetaerolite that hinders the lithium intercalation.

  1. Effective oscillator strength distributions of spherically symmetric atoms for calculating polarizabilities and long-range atom-atom interactions

    CERN Document Server

    Jiang, Jun; Cheng, Yongjun; Bromley, M W J

    2014-01-01

    Effective oscillator strength distributions are systematically generated and tabulated for the alkali atoms, the alkaline-earth atoms, the alkaline-earth ions, the rare gases and some miscellaneous atoms. These effective distributions are used to compute the dipole, quadrupole and octupole static polarizabilities, and are then applied to the calculation of the dynamic polarizabilities at imaginary frequencies. These polarizabilities can be used to determine the long-range $C_6$, $C_8$ and $C_{10}$ atom-atom interactions for the dimers formed from any of these atoms and ions, and we present tables covering all of these combinations.

  2. [High current microsecond pulsed hollow cathode lamp excited ionic fluorescence spectrometry of alkaline earth elements in inductively coupled plasma with a Fassel-torch].

    Science.gov (United States)

    Zhang, Shao-Yu; Gong, Zhen-Bin; Huang, Ben-Li

    2006-02-01

    High current microsecond pulsed hollow cathode lamp (HCMP-HCL) excited ionic fluorescence spectrometry (IFS) of alkaline earth elements in inductively coupled plasma (ICP) with a Fassel-torch has been investigated. In wide condition ranges only IFS was observed, whilst atomic fluorescence spectrometry (AFS) was not detectable. More intense ionic fluorescence signal was observed at lower observation heights and at lower incident RF powers. Without introduction of any reduction organic gases into the ICP, the limit of detection (LOD, 3sigma) of Ba was improved by 50-fold over that of a conventional pulsed (CP) HCL with the Baird sleeve-extended torch. For Ca and Sr, the LODs by HCMP-HCL-ICP-IFS and CP-HCL-ICP-AFS show no significant difference. Relative standard deviations were 0.6%-1.4% (0.1-0.2 microg x mL(-1), n = 10) for 5 ionic fluorescence lines. Preliminary studies showed that the intensity of ionic fluorescence could be depressed in the presence of K, Al and P.

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

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

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

  4. The effects of low earth orbit atomic oxygen on the properties of Polytetrafluoroethylene

    Science.gov (United States)

    Hooshangi, Zhila; Hossein Feghhi, Seyed Amir; Saeedzadeh, Rezgar

    2016-02-01

    Polymers are widely used in space systems as the structural materials. The low earth orbit (LEO) space environment includes hazards such as atomic oxygen. Exposure of polymeric materials to atomic oxygen results in destructive effects on the chemical, electrical, thermal, optical and mechanical properties as well as surface degradation. In the present work, the effects of atomic oxygen on the mechanical, thermal, and optical properties of Polytetrafluoroethylene film have been investigated. The atomic oxygen density was calculated by SPENVIS tool. After the atomic oxygen exposure by using radio-frequency (RF) plasma source, the appearance of the samples changed, and the mass of the samples reduced because of outgassing. The results of thermal analysis showed that atomic oxygen flux does not affect thermal degradation of samples regarding TGA diagrams. By increasing the atomic oxygen flux, the amount of absorbance increased showing that atomic oxygen had damaged the surface of Polytetrafluoroethylene, and it had oxidized the surface of the polymer.

  5. Effects of alternating current imposition and alkaline earth elements on modification of primary Mg_2Si crystals in hypereutectic Mg-Si alloy

    Institute of Scientific and Technical Information of China (English)

    DU Jun; K. IWAI; LI Wen-fang; PENG Ji-hua

    2009-01-01

    The effects of alternating current imposition and/or alkaline earth elements on modification of the primary Mg_2Si crystals in the hypereutectic Mg-Si alloy were investigated. An alternating current of 60 A with frequency of 1 kHz was applied into the hypereutectic Mg-Si melt which was alloyed with alkaline earth elements or not in the fixed temperature range from 700 to 630 ℃. The results show that the primary Mg_2Si crystals could be refined by imposing alternating current or adding alkaline elements. Compared with the samples treated by adding 0.4% Ca or 0.4% Sr, higher modification efficiency could be obtained for the samples treated by imposing alternating current. No further modification efficiency could be obtained for the samples treated by imposing alternating current combined with 0.4% Ca or 0.4% Sr addition.

  6. Design of a novel optically stimulated luminescent dosimeter using alkaline earth sulfides doped with SrS:Eu,Sm materials

    Institute of Scientific and Technical Information of China (English)

    Yanping Liu; Zhaoyang Chen; Yanwei Fan; Weizhen Ba; Wu Lu; Qi Guo; Shilie Pan; Aimin Chang; Xinqiang Tang

    2008-01-01

    Optically stimulated luminescence (OSL) is the luminescence emitted from an irradiated insulator or semiconductor during exposure to light.The OSL intensity is a function of the dose of radiation absorbed by the sample and thus can be used as the basis of a radiation dosimetry method.Alkaline earth sulfides doped with rare-earth elements such as Ce,Sm and Eu are OSL dosimeters having very high sensitivity,and the OSL with a short time constant is separated from the stimulated light.In this paper,a novel OSL dosimeter designed with SrS:Eu,Sm materials is described.The dosimeter takes advantage of the characteristics of charge trapping materials SrS:Eu,Sm that exhibit OSL.The measuring range of the dosimeter is from 0.01 to 100Gy.The equipment,which is relatively simple and small in size,is promising for applications in space exploration and high dose radiation dosimetry.

  7. Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

    Science.gov (United States)

    Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

    2016-08-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Bacontaining copper dopants.

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

    Institute of Scientific and Technical Information of China (English)

    许新; 朱屯

    2002-01-01

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

  9. The determination of traces of rare earths in other rare earths by atomic absorption with electrothermal atomization and by d.c. arc emission spectrography

    International Nuclear Information System (INIS)

    The determination of traces of some rare earth elements (Yb, Eu, Tm, Sm, Dy, Ho, Er) in matrices of other rare earths by a.a.s. with electrothermal atomization (tantalum ribbon), and of traces of Tm and Dy by a.e.s. with d.c. arc excitation is described. The influence of the boiling points of the traces and matrices on the possibility and the sensitivity of the a.a.s. determinations is discussed. The results of the methods are compared. Better absolute, and in most cases also relative, detection limits can be achieved by a.a.s

  10. The effects of solidification and atomization on rare-earth alloys

    Science.gov (United States)

    Anderson, Iver E.; Osborne, M. G.; Ellis, T. W.

    1996-03-01

    This article discusses the results of experiments involving the application of atomization techniques to the production of three selected rare-earth intermetallic (REI) materials. High-pressure gas atomization and centrifugal atomization into a rotating quench bath have been used to process the alloys. Rapid-solidification processing by atomization techniques is of great benefit since optimum performance of these REI materials demands chemical and structural homogeneity. The results demonstrate that such careful solidification microstructure control is required if the benefits of REI-alloy properties are to be realized with maximum processing efficiency.

  11. Hyperpolarizabilities of alkaline-earth metal ions Be+, Mg+, and Ca+

    Science.gov (United States)

    Yin, Dong; Zhang, Yong-Hui; Li, Cheng-Bin; Gao, Ke-Lin; Shi, Ting-Yun

    2016-09-01

    The knowledge of the hyperpolarizabilities of atoms and ions is helpful for the analysis of the high order effects of the frequency shifts in precision spectroscopy experiments. Liu et al. [Phys. Rev. Lett. 114, 223001 (2015)] proposed to establish all-optical trapped ion clocks using laser at the magic wavelength for clock transition. To evaluate the high-order frequency shifts in this new scheme of optical clocks, hyperpolarizabilities are needed, but absent. Using the finite field method based on the B-spline basis set and model potentials, we calculated the electric-field-dependent energy shifts of the ground and low-lying excited states in Be+, Mg+, and Ca+ in the field strength range of 0.0-6×10-5 a.u.. The scalar and tensor polarizabilities ( α 0, α 2) and hyperpolarizabilities ( γ 0, γ 2, γ 4) were deduced. The results of the hyperpolarizabilities for Be+ showed good agreement with the values in literature, implying that the present method can be applied for the effective estimation of the atomic hyperpolarizabilities, which are rarely reported but needed in experiments. The feasibility of optical trapping of Ca+ is discussed, and the contributions of hyperpolarizabilities to the transition frequency shift for Ca+ in the optical dipole trap are estimated using quasi-electrostatic approximation.

  12. Mass Spectrometric Observation of Doubly Charged Alkaline-Earth Argon Ions.

    Science.gov (United States)

    Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef

    2016-09-01

    Doubly charged diatomic ions MAr(2+) where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr(2+) , 0.4 % for CaAr(2+) , 0.2 % for SrAr(2+) and 0.1 % for BaAr(2+) relative to the corresponding doubly charged atomic ions M(2+) . It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies (D0 ) were calculated and agree well with previously published values. The abundance ratios MAr(+) /M(+) and MAr(2+) /M(2+) generally follow the predicted bond dissociation energies with the exception of MgAr(2+) . Mg(2+) should form the strongest bond with Ar [D0 (MgAr(2+) )=124 to 130 kJ mol(-1) ] but its relative abundance is similar to that of the weakest bound BaAr(2+) (D0 =34 to 42 kJ mol(-1) ). The relative abundances of the various MAr(2+) ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr(2+) ions relative to the composition in the source. The corresponding singly charged MAr(+) ions are also observed but occur at about three orders of magnitude lower intensity than MAr(2+) . PMID:27252087

  13. Sm{sup 3+}-doped alkaline earth borate glasses as UV→visible photon conversion layer for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, L.F. [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Chen, B.J.; Pun, E.Y.B. [Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lin, H., E-mail: lhai8686@yahoo.com [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-04-15

    Intense multi-peak red fluorescence emissions of Sm{sup 3+} are exhibited in alkaline-earth borate (LKZBSB) glasses under UV radiation. The spontaneous emission probabilities A{sub rad} corresponding to the {sup 4}G{sub 5/2}→{sup 6}H{sub J} (J=5/2, 7/2, 9/2 and 11/2) transitions are derived to be 24.74, 129.72, 117.03 and 32.23 s{sup −1}, respectively, and the relevant stimulated emission cross-sections σ{sub em} are 0.77×10{sup −22}, 4.46×10{sup −22}, 5.05×10{sup −22} and 1.38×10{sup −22} cm{sup 2}, confirming the effectiveness of red luminescence in Sm{sup 3+}-doped LKZBSB glasses. Quantitative characterization through the evaluation of absolute spectral parameters reveals that the quantum yield of Sm{sup 3+}-doped LKZBSB glasses is as high as 13.29%. Furthermore, with the introduction of Ce{sup 3+}, the effective excitation wavelength range and the emission intensity of Sm{sup 3+} in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of 9.02 in the UVB region. These results demonstrate that the present glass system has promising potential as an efficient UV→visible photon conversion layer for the enhancement of solar cell efficiency, including appealing applications in outer space. - Highlights: • Intense multi-peak red fluorescence emissions of Sm{sup 3+} are exhibited under UV radiation. • Effectiveness of red luminescence is confirmed by stimulated emission cross-sections. • Quantum yield of Sm{sup 3+}-doped LKZBSB glasses is 13.29% by quantitative characterization. • Effective excitation wavelength range and emission intensity are improved with Ce{sup 3+} doping. • Alkaline-earth borate glass has potential as solar cell UV→Vis photon conversion layer.

  14. Measuring the Earth's gravity field with cold atom interferometers

    CERN Document Server

    Carraz, Olivier; Massotti, Luca; Haagmans, Roger; Silvestrin, Pierluigi

    2015-01-01

    The scope of the paper is to propose different concepts for future space gravity missions using Cold Atom Interferometers (CAI) for measuring the diagonal elements of the gravity gradient tensor, the spacecraft angular velocity and the spacecraft acceleration. The aim is to achieve better performance than previous space gravity missions due to a very low white noise spectral behaviour of the CAI instrument and a very high common mode rejection, with the ultimate goals of determining the fine structures of the gravity field with higher accuracy than GOCE and detecting time-variable signals in the gravity field.

  15. A new N-hydroxyethyliminodiacetic acid modified core-shell silica phase for chelation ion chromatography of alkaline earth, transition and rare earth elements.

    Science.gov (United States)

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Stack, Elaine M; Omamogho, Jesse O; Glennon, Jeremy D; Paull, Brett

    2013-12-20

    Bare core-shell silica (1.7μm) has been modified with iminodiacetic acid functional groups via standard silane chemistry, forming a new N-hydroxyethyliminodiacetic acid (HEIDA) functionalised core-shell stationary phase. The column was applied in high-performance chelation ion chromatography and evaluated for the retention of alkaline earth, transition and heavy metal cations. The influence of nitric acid eluent concentration, addition of complexing agent dipicolinic acid, eluent pH and column temperature on the column performance was investigated. The efficiencies obtained for transition and heavy metal cations (and resultant separations) were comparable or better than those previously obtained for alternative fully porous silica based chelation stationary phases, and a similarly modified monolithic silica column, ranging from ∼15 to 56μm HETP. Increasing the ionic strength of the eluent with the addition of KNO3 (0.75M) and increasing the column temperature (70°C) facilitated the isocratic separation of a mixture of 14 lanthanides and yttrium in under 12min, with HETP averaging 18μm (7μm for Ce(III)).

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

    International Nuclear Information System (INIS)

    An international programme of work is currently under way to develop methods for calculating doses to infants from ingestion of radionuclides present in mothers' milk. This paper considers the special case of the alkaline earth elements. Models have been developed for 45Ca, 90Sr and 226Ra and the sensitivity of results to various changes in parameter values is discussed. A complication when calculating doses from intakes of radium is that the International Commission on Radiological Protection has previously recommended that doses from decay products of radium should be calculated using element-specific biokinetic models (so-called independent biokinetics). An extension of this method to the models for breastfeeding is proposed. Preliminary estimates of the doses received by the infant for a number of maternal intake scenarios show that doses to the infant can exceed the corresponding adult dose, such as for 45Ca (ratio = 3.1) while, in other cases such as 90Sr, the infant dose can be a significant fraction of the adult dose. (author)

  17. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides.

    Science.gov (United States)

    Hereijgers, Bart P C; Weckhuysen, Bert M

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with all studied catalyst materials, however, the selectivity for hydrogen increased from 15 % to 51 % when going from the unpromoted to a BaO-promoted catalyst. The formation of the undesired byproducts CO, methane, and dimethyl ether was considerably reduced as well. The observed trend in catalyst performance follows the trend in increasing basicity of the studied promoter elements, indicating a chemical effect of the promoter material. Superior catalytic performance, in terms of H(2) and CO selectivity, was obtained with a Au/La(2)O(3) catalyst. At 300 degrees C the hydrogen selectivity reached 80 % with only 2 % CO formation, and the catalyst displayed a stable performance over at least 24 h on-stream. Furthermore, the formation of CO was found to be independent of the oxygen concentration in the feed. The commercial lanthanum oxide used in this study had a low specific surface area, which led to the formation of relative large gold particles. Therefore, the catalytic activity could be enhanced by decreasing the gold particle size through deposition on lanthanum oxide supported on high-surface-area alumina.

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

    CERN Document Server

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

    2012-01-01

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

  19. Promoting alkali and alkaline-earth metals on MgO for enhancing CO2 capture by first-principles calculations.

    Science.gov (United States)

    Kim, Kiwoong; Han, Jeong Woo; Lee, Kwang Soon; Lee, Won Bo

    2014-12-01

    Developing next-generation solid sorbents to improve the economy of pre- and post-combustion carbon capture processes has been challenging for many researchers. Magnesium oxide (MgO) is a promising sorbent because of its moderate sorption-desorption temperature and low heat of sorption. However, its low sorption capacity and thermal instability need to be improved. Various metal-promoted MgO sorbents have been experimentally developed to enhance the CO2 sorption capacities. Nevertheless, rigorous computational studies to screen an optimal metal promoter have been limited to date. We conducted first-principles calculations to select metal promoters of MgO sorbents. Five alkali (Li-, Na-, K-, Rb-, and Cs-) and 4 alkaline earth metals (Be-, Ca-, Sr-, and Ba-) were chosen as a set of promoters. Compared with the CO2 adsorption energy on pure MgO, the adsorption energy on the metal-promoted MgO sorbents is higher, except for the Na-promoter, which indicates that metal promotion on MgO is an efficient approach to enhance the sorption capacities. Based on the stabilized binding of promoters on the MgO surface and the regenerability of sorbents, Li, Ca, and Sr were identified as adequate promoters among the 9 metals on the basis of PW91/GGA augmented with DFT+D2. The adsorption energies of CO2 on metal-promoted MgO sorbents for Li, Ca, and Sr atoms are -1.13, -1.68, and -1.48 eV, respectively. PMID:25319405

  20. Synthesis, characterization and solubility of alkaline earth uranyl carbonates M2[UO2(CO3)3].xH20; M: Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    The release and dispersion of uranium from closed uranium mining sites and the resulting uranium contamination of the natural environment of such sites is a major problem examined in this dissertation. Knowledge of the pollution pathways and processes is indispensable for an assessment of the radiological implications for the human population, to be taken into account in the planning of site rehabilitation work. The formation of secondary uranium minerals may contribute to an immobilization of the uranium, but it is possible as well that such secondary uranium minerals will release uranium. A major task of this dissertation therefore was to examine the conditions of formation of alkaline earth uranyl carbonates in the context of their natural occurrence as observed at some sites, and to answer the question of whether hitherto unknown alkaline earth uranyl carbonates may form in the natural environment, and ought to be taken into account as new source terms. (orig./CB)

  1. Interaction of an aluminum atom with an alkaline earth atom: Spectroscopic and ab initio investigations of AlCa

    Science.gov (United States)

    Behm, Jane M.; Morse, Michael D.; Boldyrev, Alexander I.; Simons, Jack

    1994-10-01

    A spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 Al:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 13 500 to 17 900 cm-1. These are the [13.5] 2Πr, the [15.8] 2Σ, the [17.0] 2Δ3/2(?), and the [17.6] 2Δ3/2 states. From rotational analysis excited state bond lengths have been measured for three of the four excited states, and the ground state has been unambiguously determined as a 2Πr state with a weighted least squares value of the ground state bond length of r0` = 3.1479± 0.0010 Å. The ionization energy of the molecule has also been directly determined as 5.072±0.028 eV. Ab initio calculations for the potential energy curves of seven low-lying states of AlCa [X 2Πr, 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ-] and for the X 1Σ+ ground electronic state of AlCa+ have been carried out. In agreement with experiment, 2Πr is calculated to be the ground electronic state of the neutral molecule. The dissociation energies of AlCa (X 2Πr) into Al(3s23p1,2P0)+Ca(4s2,1S) and for AlCa+ (X 1Σ+) into Al+(3s2,1S)+Ca(4s2,1S) are calculated to be 0.47 and 1.50 eV, respectively. The excited 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ- states are calculated to lie 0.2, 0.7, 0.7, 1.1, 1.1, and 1.1 eV above X 2Πr, respectively, and the vertical and adiabatic ionization energies of AlCa have been calculated to be 5.03 and 4.97 eV, respectively.

  2. THEORETICAL-ANALYSIS OF THE O(1S) BINDING-ENERGY SHIFTS IN ALKALINE-EARTH OXIDES - CHEMICAL OR ELECTROSTATIC CONTRIBUTIONS

    NARCIS (Netherlands)

    PACCHIONI, G; BAGUS, PS

    1994-01-01

    We report results from ab initio cluster-model calculations on the O(1s) binding energy (BE) in the alkaline-earth oxides, MgO, CaO, SrO, and BaO; all these oxides have a cubic lattice structure. We have obtained values for both the initial- and final-state BE's. A simple point-charge model, where a

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

    OpenAIRE

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

    2016-01-01

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

  4. Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

    Science.gov (United States)

    Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

    2015-10-01

    Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

  5. Structural criteria for the rational design of selective ligands. Extension of the MM3 force field to aliphatic ether complexes of the alkali and alkaline earth cations

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B.P.; Rustad, J.R. (Pacific Northwest Lab., Richland, WA (United States))

    1994-07-13

    Structural requirements for strain-free metal ion complexation by an aliphatic ether group are investigated through the use of both ab initio molecular orbital and molecular mechanics calculations. Hartree-Fock calculations on simple models, M-O(Me)[sub 2] and M-O(Me)(Et), reveal a preference for trigonal planar geometry when aliphatic ether oxygens are coordinated to alkali and alkaline earth cations. This preference is found to be strongest in small, high-valent cations and weakest in large, low-valent cations. Results from the Hartree-Fock calculations are used to extend the MM3 force field for calculation on aliphatic ether complexes with the alkali (Li to Cs) and alkaline earth (Mg to Ba) cations. The resulting molecular model (i) reproduces the experimental crystal structures of 51 different complexes of multidentate ethers with alkali and alkaline earth cations, (ii) explains experimental trends in the structure of five-membered chelate rings of aliphatic ethers, (iii) reveals a fundamental difference between the metal ion size selectivity of five-membered chelate rings of ethers versus that of amines, and (iv) rationalizes trends in the stability of four potassium complexes with the diasteriomers of dicyclohexyl-18-crown-6. 40 refs., 9 figs., 5 tabs.

  6. 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.

  7. Band structure and electrical properties of MBE grown HfO{sub 2} - based alkaline earth Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Dudek; Grzegorz, Lupina; Grzegorz, Kozlowski; Jarek, Dabrowski; Gunther, Lippert; Hans-Joachim, Muessig; Thomas, Schroeder [IHP-Microelectronics, Frankfurt, Oder (Germany); Dieter, Schmeisser [BTU, Cottbus (Germany)

    2010-07-01

    Ultra thin dielectric films (<20 nm) deposited on TiN electrodes are interesting for MIM capacitor application. High capacitance density and dielectric permittivity must be accompanied by extremely low leakage currents (10{sup -8} A/cm{sup 2}) at bias 0.5 V. To achieve such low leakage currents, high band gap and proper band alignment is required. Occupied electronic states can be probed with standard laboratory photoemission methods. Probing of unoccupied states is more challenging. Synchrotron based PES in combination with XAS forms a powerful method to study the band alignment. ASAM end station located at the U 49/2 PGM 2 beamline of BESSY II (Berlin) offers excellent conditions for performing such measurements. We investigated HfO{sub 2} - based alkaline earth perovskite - BaHfO{sub 3} with subsequent admixture of TiO{sub 2}, resulting in formation of BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} compound. The analysis of data indicates that band gap for HfO{sub 2} is similar to BaHfO{sub 3} and amounts 5.8 eV; for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} it decreases to 3.8 eV. We conclude that the addition of TiO{sub 2} to BaHfO{sub 3} increases significantly the dielectric permittivity but also impacts the band gap alignment. The conduction band offset shrinks, influencing the leakage current behavior.

  8. Ab Initio Quantum Mechanical Study of the Structure and Stability of the Alkaline Earth Metal Oxides and Peroxides

    Science.gov (United States)

    Königstein, Markus; Catlow, C. Richard A.

    1998-10-01

    We report a detailed computationally study of the stability of the alkaline earth metal peroxidesMO2(M=Ba, Sr, Ca, Mg, Be) with respect to decomposition into the corresponding oxidesMOand molecular oxygen using Hartree-Fock and density functional theory (DFT) techniques. A comparison between calculated and experimental binding energies indicates that the DFT method is most suitable for a correct description of the peroxide bond. The DFT reaction energies for the peroxide decompositionMO2→MO+{1}/{2}O2show that only BaO2and SrO2are thermodynamically stable compounds, while CaO2(in the calcium carbide structure), MgO2, and BeO2(in the pyrite structure) are energetically unstable with reaction energies of -24.7, -26.8, and -128.7kJ/mol, respectively, and are therefore unlikely to exist as pure compounds. The published calcium carbide structure for CaO2is probably incorrect, at least for pure calcium peroxide, since apart from the thermodynamical instability the compound is more stable in the pyrite structure by 25.5 kJ/mol. Our analysis suggests that the water and/or hydrogen peroxide content of experimentally prepared MgO2samples is necessary for the stabilization of the structure, while BeO2is clearly unstable under ambient conditions. We studied also the effect of the zero point energies and the entropies on the decomposition free energies and, for this purpose, performed atomistic lattice simulations based on interatomic potentials, which we derived from ourab initiodata; the results indicate a negligible effect of the zero point energies, while the entropy terms favor the decomposition reaction by ca. 20 kJ/mol at 298.15 K.

  9. Ab initio quantum mechanical study of the structure and stability of the alkaline earth metal oxides and peroxides

    Energy Technology Data Exchange (ETDEWEB)

    Koenigstein, M.; Catlow, C.R.A. [Royal Institution of Great Britain, London (United Kingdom). Davy Faraday Research Lab.

    1998-10-01

    The authors report a detailed computational study of the stability of the alkaline earth metal peroxides MO{sub 2} (M = Ba, Sr, Ca, Mg, Be) with respect to decomposition into the corresponding oxides Mo and molecular oxygen using Hartree-Fock and density functional theory (DFT) techniques. A comparison between calculated and experimental binding energies indicates that the DFT method is most suitable for a correct description of the peroxide bond. The DFT reaction energies for the peroxide decomposition MO{sub 2} {yields} MO + {1/2}O{sub 2} show that only BaO{sub 2} and SrO{sub 2} are thermodynamically stable compounds, while CaO{sub 2} (in the calcium carbide structure), MgO{sub 2}, and BeO{sub 2} (in the pyrite structure) are energetically unstable with reaction energies of {minus}24.7, {minus}26.8, and {minus}128.7 kJ/mol, respectively, and are therefore unlikely to exist as pure compounds. The published calcium carbide structure for CaO{sub 2} is probably incorrect, at least for pure calcium peroxide, since apart from the thermodynamical instability the compound is more stable in the pyrite structure by 25.5 kJ/mol. The analysis suggests that the water and/or hydrogen peroxide content of experimentally prepared MgO{sub 2} samples is necessary for the stabilization of the structure, while BeO{sub 2} is clearly unstable under ambient conditions. The authors studied also the effect of the zero point energies and the entropies on the decomposition free energies and, for this purpose, performed atomistic lattice simulations based on interatomic potentials, which they derived from their ab initio data; the results indicate a negligible effect of the zero point energies, while the entropy terms favor the decomposition reaction by ca. 20 kJ/mol at 298.15 K.

  10. Photoelectron Experiments and Studies of X-Ray Absorption Near Edge Structure in Alkaline-Earth and Rare - Fluorides.

    Science.gov (United States)

    Gao, Yuan

    Alkaline-earth fluorides and rare-earth trifluorides possess technological importance for applications in multi -layer electronic device structures and opto-electronic devices. Interfaces between thin films of YbF _3 and Si(111) substrates were studied by photoelectron spectroscopy and x-ray absorption spectroscopy using synchrotron radiation. Results of YbF_3 /Si(111) were compared with those of TmF _3/Si(111). While electrons in the Si valence band are prevented from occupying the empty 4f levels in TmF_3 at the interface by the on -site Coulomb repulsion energy, the charge transfer from Si to YbF_3 is possible because the totally filled 4f states in Yb still lie below the Si valence band maximum. The theory of x-ray absorption near edge structure (XANES) is incomplete except for a few particularly simple special cases. A Bragg reflection model was developed to qualitatively explain the oscillations in XANES, in terms of the scattering of the photoelectron wave between families of lattice planes as set out by the Bragg condition for backscattering. The model was found to represent the data for systems with nearly free electron like conduction bands reasonably well. High resolution CaF_2 fluorine K edge XANES was used as a prototype to understand XANES in more depth on systems with strong core hole effects. Unlike previous work which involved multiple scattering cluster calculations that include only short range order effects, both the long range order and the symmetry breaking core holes are included in a new bandstructure approach in which the core hole is treated with a supercell technique. A first principles calculation with the use of pseudopotentials successfully reproduced all the main features of the first 15 eV of the fluorine K edge in CaF_2 which had not been explained with the cluster calculations. A comparison of the theoretical and experimental fluorine K edges in CaF_2 and BaF _2 was used to identify the structure related features. The possibility

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

    Directory of Open Access Journals (Sweden)

    Kui-Rong Ma

    2013-01-01

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

  12. Electronic structure, optical properties and bonding in alkaline earth halo-fluoride scintillators: BaClF, BaBrF and BaIF

    Energy Technology Data Exchange (ETDEWEB)

    Yedukondalu, N. [University of Hyderabad; Babu, K. Ramesh [University of Hyderabad; Bheemalingam, Ch. [University of Hyderabad; Singh, David J [ORNL; Vaitheeswaran, G. [University of Hyderabad; Kanchana, V. [IIT Hyderabad

    2011-01-01

    We report first-principles studies of the structural, electronic, and optical properties of the alkaline-earth halofluorides, BaXF (X = Cl, Br, and I), including pressure dependence of structural properties. The band structures show clear separation of the halogen p derived valence bands into higher binding energy F and lower binding energy X derived manifolds reflecting the very high electronegativity of F relative to the other halogens. Implications of this for bonding and other properties are discussed. We find an anisotropic behavior of the structural parameters especially of BaIF under pressure. The optical properties on the other hand are almost isotropic, in spite of the anisotropic crystal structures.

  13. Electronic structures and magnetic properties of rare-earth-atom-doped BNNTs

    Science.gov (United States)

    Ren, Juan; Zhang, Ning-Chao; Wang, Peng; Ning, Chao; Zhang, Hong; Peng, Xiao-Juan

    2016-04-01

    Stable geometries, electronic structures, and magnetic properties of (8,0) and (4,4) single-walled BN nanotubes (BNNTs) doped with rare-earth (RE) atoms are investigated using the first-principles pseudopotential plane wave method with density functional theory (DFT). The results show that these RE atoms can be effectively doped in BNNTs with favorable energies. Because of the curvature effect, the values of binding energy for RE-atom-doped (4,4) BNNTs are larger than those of the same atoms on (8,0) BNNTs. Electron transfer between RE-5 d, 6 s, and B-2 p, N-2 p orbitals was also observed. Furthermore, electronic structures and magnetic properties of BNNTs can be modified by such doping. The results show that the adsorption of Ce, Pm, Sm, and Eu atoms can induce magnetization, while no magnetism is observed when BNNTs are doped with La. These results are useful for spintronics applications and for developing magnetic nanostructures.

  14. Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)

    Energy Technology Data Exchange (ETDEWEB)

    Juergens, Barbara; Irran, Elisabeth; Schnick, Wolfgang

    2001-03-01

    The alkaline earth dicyanamides Mg[N(CN){sub 2}]{sub 2}, Ca[N(CN){sub 2}]{sub 2}, Sr[N(CN){sub 2}]{sub 2}, and Ba[N(CN){sub 2}]{sub 2} were synthesized by ion exchange using Na[N(CN){sub 2}] and the respective nitrates or bromides as starting materials. The crystal structures were determined from X-ray powder diffractometry: Mg[N(CN){sub 2}]{sub 2}, Pnnm, Z=2, a=617.14(3), b=716.97(3), and c=740.35(5) pm; Ca[N(CN){sub 2}]{sub 2} and Sr[N(CN){sub 2}]{sub 2}, C2/c, Z=4; Ca[N(CN){sub 2}]{sub 2}, a=1244.55(3), b=607.97(1), and c=789.81(1) pm, {beta}=98.864(2){degree}; Sr[N(CN){sub 2}]{sub 2}, a=1279.63(2), b=624.756(8), and c=817.56(1) pm, {beta}=99.787(1){degree}; Ba[N(CN){sub 2}]{sub 2}, Pnma, Z=4, a=1368.68(7), b=429.07(7), and c=1226.26(2) pm. The dicyanamides consist of the respective alkaline earth cations and bent planar [N(CN){sub 2}]{sup -} ions. The structural features were correlated with vibrational spectroscopic data. The thermal behavior was studied by thermoanalytical experiments.

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

    Science.gov (United States)

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

    2015-09-01

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

  16. Coordination and ion-ion interactions of chromium centers in alkaline earth zinc borate glasses probed by electron paramagnetic resonance and optical spectroscopy

    Science.gov (United States)

    Sumalatha, B.; Omkaram, I.; Rajavardana Rao, T.; Linga Raju, Ch

    2013-05-01

    Electron paramagnetic resonance (EPR), optical absorption and FT-IR studies have been carried out on chromium ions incorporated in alkaline earth zinc borate glasses. The EPR spectra exhibit two resonance signals with effective g values at g ≈ 1.99 and ≈1.97. The resonance signal at g ≈ 1.99 is attributed to the contribution from both the exchange coupled Cr3+-Cr3+ ion pairs and the isolated Cr3+ ions and the resonance signal at g ≈ 1.97 is due to Cr5+ ions. The paramagnetic susceptibility (χ) was calculated from the EPR data at various (123-303 K) temperatures and the Curie temperature (θp) was calculated from the 1/χ-T graph. The optical absorption spectra exhibit three bands at ˜360 nm, ˜440 nm and a broad band at ˜615 nm characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal-field splitting parameter Dq and the Racah parameters (B and C) have been evaluated. From the ultraviolet edges, the optical band gap energies (Eopt) and Urbach energy (ΔE) are calculated. The theoretical optical basicity (Λth) of these glasses has also been evaluated. Chromium ions doped alkaline earth zinc borate glasses show BO3 and BO4 structural units in the FT-IR studies.

  17. Coordination and ion–ion interactions of chromium centers in alkaline earth zinc borate glasses probed by electron paramagnetic resonance and optical spectroscopy

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR), optical absorption and FT-IR studies have been carried out on chromium ions incorporated in alkaline earth zinc borate glasses. The EPR spectra exhibit two resonance signals with effective g values at g ≈ 1.99 and ≈1.97. The resonance signal at g ≈ 1.99 is attributed to the contribution from both the exchange coupled Cr3+–Cr3+ ion pairs and the isolated Cr3+ ions and the resonance signal at g ≈ 1.97 is due to Cr5+ ions. The paramagnetic susceptibility (χ) was calculated from the EPR data at various (123–303 K) temperatures and the Curie temperature (θp) was calculated from the 1/χ–T graph. The optical absorption spectra exhibit three bands at ∼360 nm, ∼440 nm and a broad band at ∼615 nm characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal-field splitting parameter Dq and the Racah parameters (B and C) have been evaluated. From the ultraviolet edges, the optical band gap energies (Eopt) and Urbach energy (ΔE) are calculated. The theoretical optical basicity (Λth) of these glasses has also been evaluated. Chromium ions doped alkaline earth zinc borate glasses show BO3 and BO4 structural units in the FT-IR studies. (paper)

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

    Science.gov (United States)

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

    2015-09-01

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

  19. Earth sciences uranium geology, exploration and mining, hydrology, 1986-1998. International Atomic Energy Agency publications

    International Nuclear Information System (INIS)

    This catalogue lists sales publications of the International Atomic Energy Agency dealing with Earth Sciences issued during the period 1986-1998. Most publications are published in English. Proceedings of conferences, symposia and panels of experts may contain some papers in languages other than English (French, Russian or Spanish), but all these papers have abstracts in English. It should be noted that prices of books are quoted in Austrian Schillings. The prices do not include local taxes and are subject to change without notice. All books in this catalogue are 16 x 24 cm, paper-bound, unless otherwise stated

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

    Science.gov (United States)

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

    2016-04-01

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

  1. High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies

    International Nuclear Information System (INIS)

    A high intensity (1019O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 1022 O-atoms/cm2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O2 mixtures. Visible and infrared photon flux levels of 1 watt/cm2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 /times/ 10/sup /minus/24/ cm /+-/ 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H2O, NO, CO2). Teflon reacts with ∼0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs

  2. Adsorption of rare-earth atoms onl silicon carbide nanotube: a density-functional study

    Science.gov (United States)

    An, Zhiwei; Shen, Jiang

    2014-07-01

    In this paper, we investigate the adsorption of a series of rare-earth (RE) metal atoms (La, Pr, Nd, Sm and Eu) on the pristine zigzag (8, 0) silicon carbide nanotube (SiCNT) using density functional theory (DFT). Main focuses are placed on the stable adsorption sites, the corresponding binding energies, and the modified electronic properties of the SiC nanotubes due to the adsorbates. A single RE atom prefers to adsorb strongly at the hollow site with relatively high binding energy (larger than 1.0 eV). Due to the rolling effect of single-walled SiCNTs, the inside configurations are more stable than the outside ones. For RE-adsorbed systems, the adsorption of metal atoms induces certain impurity states within the band gap of the pristine SiCNT. Furthermore, we analyze there exists hybridizations between RE-5d, 6s, C-2p and Si-3p orbitals for the RE atom adsorption on the SiCNTs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  4. Comparative investigation on the effect of alkaline earth oxides on the intensity of absorption bands due to Cu2+, Mn3+ and Cr3+ ions in ternary silicate glasses

    Indian Academy of Sciences (India)

    S P Singh; Aman; Anal Tarafder

    2004-06-01

    Absorption characteristics of Cu2+, Mn3+ and Cr3+ ions in ternary silicate (20Na2O.10RO.70SiO2, where R=Ca, Sr, Ba) glasses were investigated. The intensities of absorption bands due to Cu2+ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case of Mn3+ and Cr3+ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu2+, Mn3+ and Cr3+ ion is attributed due to change in silicate glass compositions.

  5. Volatilisation of alkali and alkaline earth metallic species during the pyrolysis of biomass: differences between sugar cane bagasse and cane trash.

    Science.gov (United States)

    Keown, Daniel M; Favas, George; Hayashi, Jun-ichiro; Li, Chun-Zhu

    2005-09-01

    Sugar cane bagasse and cane trash were pyrolysed in a novel quartz fluidised-bed/fixed-bed reactor. Quantification of the Na, K, Mg and Ca in chars revealed that pyrolysis temperature, heating rate, valence and biomass type were important factors influencing the volatilisation of these alkali and alkaline earth metallic (AAEM) species. Pyrolysis at a slow heating rate (approximately 10 K min(-1)) led to minimal (often biomass samples. Fast heating rates (>1000 K s(-1)), encouraging volatile-char interactions with the current reactor configuration, resulted in the volatilisation of around 80% of Na, K, Mg and Ca from bagasse during pyrolysis at 900 degrees C. Similar behaviour was observed for monovalent Na and K with cane trash, but the volatilisation of Mg and Ca from cane trash was always restricted. The difference in Cl content between bagasse and cane trash was not sufficient to fully explain the difference in the volatilisation of Mg and Ca.

  6. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-05

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

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

    International Nuclear Information System (INIS)

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

  11. Effect of Irregularities in the Earth's Rotation on Relativistic Shifts in Frequency and Time of Earthbound Atomic Clocks

    Science.gov (United States)

    Fateev, V. F.; Kopeikin, S. M.; Pasynok, S. L., S. L.

    2015-10-01

    The effect of irregularities in the earth's rotation (precession and nutation of the earth's axis of rotation, oscillations in the modulus of the angular velocity, periodic deviations in the line of the poles, and the angular momentum of the globe) on the frequency and time of high-stability atomic clocks are examined in terms of the theory of relativity. It is shown that the relative shift in frequency and time owing to these effects can exceed 5×10-16.

  12. Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit

    CERN Document Server

    Bzowski, M

    2008-01-01

    Contect: With the forthcoming launch of a NASA SMEX mission IBEX devoted to imaging of heliospheric interface by in-situ detection of Energetic Neutral Atoms (ENA) an important issue becomes recognizing of transport of these atoms from the termination shock of the solar wind to Earth orbit. Aims: Investigate modifications of energy and of survival probability of the H ENA detectable by IBEX (0.01 -- 6 keV) between the termination shock and Earth orbit taking into account the influence of the variable and anisotropic solar wind and solar EUV radiation. Methods: Energy change of the atoms is calculated by numerical simulations of orbits of the H ENA atoms from ~100 AU from the Sun down to Earth orbit, taking into account solar gravity and Lyman-$\\alpha$ radiation pressure, which is variable in time and depends on radial velocity of the atom. To calculate survival probabilities of the atoms against onization, a detailed 3D and time-dependent model of H ENA ionization based on observations of the solar wind and E...

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

    OpenAIRE

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

    1997-01-01

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

  14. A trapped atom interferometer with ultracold Sr atoms

    CERN Document Server

    Zhang, Xian; Mazzoni, Tommaso; Poli, Nicola; Tino, Guglielmo M

    2016-01-01

    We report on a trapped atom interferometer based on Bragg diffraction and Bloch oscillations with alkaline-earth-metal atoms. We use a Ramsey-Bord\\'e Bragg interferometer with $^{88}$Sr atoms combined with Bloch oscillations to extend the interferometer time. Thanks to a long coherence time for Bloch oscillations of $^{88}$Sr atoms, we observed interference up to 1 s evolution time in the lattice. A detailed study of decoherence sources during the Bloch phase is also presented. While still limited in sensitivity by lattice lifetime and beam inhomogeneity this result opens the way to high contrast trapped interferometers with extended interrogation time.

  15. Alkaline broadening in Stars

    CERN Document Server

    De Kertanguy, A

    2015-01-01

    Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

  16. Large-momentum-transfer Bragg interferometer with strontium atoms

    CERN Document Server

    Mazzoni, T; Del Aguila, R; Salvi, L; Poli, N; Tino, G M

    2015-01-01

    We report on the first atom interferometer based on Bragg diffraction in a fountain of alkaline-earth atoms, namely $^{88}$Sr. We demonstrate large momentum transfer to the atoms up to eight photon recoils and the use of the interferometer as a gravimeter with a sensitivity $\\delta g/g=4\\times 10^{-8}$. Thanks to the special characteristics of strontium atoms for precision measurements, this result opens a new way for experiments in fundamental and applied physics.

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

    International Nuclear Information System (INIS)

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

  18. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Yuhua; Sorescu, Dan

    2010-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-01

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

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

    Science.gov (United States)

    Duan, Yuhua; Sorescu, Dan C

    2010-08-21

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

  2. Mechanochemical synthesis, structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1-xMbxF2 (M: Ca, Sr, Ba)

    Science.gov (United States)

    Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

    2016-10-01

    The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1-xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1-xSrxF2 and Ba1-xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F- ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

    An international programme of work is currently under way to develop methods for calculating doses to infants from ingestion of radionuclides present in mothers' milk. This paper considers the special case of the alkaline earth elements. Models have been developed for {sup 45}Ca, {sup 90}Sr and {sup 226}Ra and the sensitivity of results to various changes in parameter values is discussed. A complication when calculating doses from intakes of radium is that the International Commission on Radiological Protection has previously recommended that doses from decay products of radium should be calculated using element-specific biokinetic models (so-called independent biokinetics). An extension of this method to the models for breastfeeding is proposed. Preliminary estimates of the doses received by the infant for a number of maternal intake scenarios show that doses to the infant can exceed the corresponding adult dose, such as for {sup 45}Ca (ratio = 3.1) while, in other cases such as {sup 90}Sr, the infant dose can be a significant fraction of the adult dose. (author)

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

    CERN Document Server

    Alizadeh, N

    2001-01-01

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

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

    Science.gov (United States)

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

    2016-03-24

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

  6. Atom interferometry using Bose-Einstein condensates on Earth and in space

    Science.gov (United States)

    Sackett, C. A.; Leonard, R. H.; Fallon, A.

    2015-03-01

    The Cold Atom Laboratory is a multipurpose ultracold gas experiment currently being developed for operation on the international space station. It will have the ability to demonstrate proof-of-principle atom interferometry experiments in space. By using microgravity, atom interferometry has the potential to achieve extremely good performance in sensing and navigation applications. Terrestrial experiments can be used to explore potential challenges and prior to launch. One issue of concern is the release of cold atoms from a magnetic trap into free space. Although the atoms will not fall, they can acquire relatively large velocities due to technical limitations such as stray magnetic fields. This can limit the time available for measurements and thus the atom interferometer performance.

  7. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  8. Electromigration in molten salts and application to isotopic separation of alkaline and alkaline-earth elements; Electromigration en sels fondus et application a la separation des isotopes des elements alcalins et alcalino-terreux

    Energy Technology Data Exchange (ETDEWEB)

    Menes, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The separation of the isotopes of the alkaline-earth elements has been studied using counter-current electromigration in molten bromides. The conditions under which the cathode operates as a bromine electrode for the highest possible currents have been examined. For the separation of calcium, it has been necessary to use a stable CaBr{sub 2} - (CaBr{sub 2} + KBr) 'chain'. In the case of barium and strontium, it was possible to employ the pure bromides. Enrichment factors of the order of 10 for {sup 48}Ca and of the order of 1.5 for the rare isotopes of barium and strontium have been obtained. In the case of magnesium the method is slightly more difficult to apply because of material loss due to the relatively high vapour pressure of the salt requiring the use of electrolyte chains, MgBr{sub 2} - CeBr{sub 3}. A study has been made that has led to a larger-scale application of the method. These are essentially the inhibition of reversible operation of the cathode by traces of water, limiting the intensity which can be tolerated; evacuation of the heat produced by the Joule effect, in the absence of which the separation efficiency is reduced by thermal gradients; corrosion of the materials by molten salts at high temperature. Several cells capable of treating a few kilograms of substance have been put into operation; none of these has lasted long enough to produce a satisfactory enrichment. The method is thus limited actually to yields of the order of a few grams. (author) [French] On a etudie la separation des isotopes des elements alcalino-terreux par electromigration a contre-courant en bromures fondus. On a etudie les conditions dans lesquelles la cathode fonctionne en electrode a brome pour des intensites les plus elevees possibles. Pour la separation du calcium, il a ete necessaire d'utiliser une chaine stable CaBr{sub 2} - (CaBr{sub 2} + KBr). Pour le baryum et le strontium, on a pu operer sur les bromures purs. On a obtenu des facteurs d

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

    Science.gov (United States)

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

    2016-07-25

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-14

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

  11. Chromatographic separation and inductively coupled plasma atomic emission spectrometric determination of the rare earth metals contained in terbium

    International Nuclear Information System (INIS)

    The chromatographic separation of rare earth elements (REEs), prior to inductively coupled plasma atomic emission spectrometric (ICP-AES) measurements, using a column packed with 2-ethylexyl hydrogen 2-ethyl-hexylphosphonate (PC-88A)-loaded polymer resin in order to exclude spectral interferences was examined. A favourable separation of trace amounts of metals (La, Nd and Sm) from a large amount of terbium was achieved simply by elution with dilute hydrochloric acid. Trace lanthanum and neodymium in metallic terbium were determined by separation of the analyte ions from the matrix element followed by ICP-AES analysis. (author). 16 refs.; 5 figs.; 2 tabs

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

    Directory of Open Access Journals (Sweden)

    MITHLESH AGRAWAL

    2002-04-01

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

  13. Effect of rare earth (RE) on diffusion of aluminum atoms in aluminizing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; YE Xiao-feng; PANG Bi-jun; ZHOU Si-kai

    2006-01-01

    The RE-aluminized coating and pure aluminized coating on 20 carbons steel were prepared by hot dip aluminizing method at 740 ℃. After diffusion treatment at 850 ℃ for 4 h, the distribution of aluminum and lanthanum elements in the coating was analyzed with energy disperse spectroscopy(EDS) and electron probe microanalyses(EPMA), and the lattice parameter of α-Fe in the matrix of the coating was measured precisely by X-ray diffractometer(XRD). The results show that RE permeates into the aluminized coating, leads to lattice disturbance and increases the depth of the aluminized coating. On the basis of the results, the expression of the diffusion coefficient of Al atoms is derived from the diffusion flow, and the effect of the high vacancy concentration and high concentration gradient of vacancies on the diffusion of Al atoms was analyzed by establishing the kinetics model of the vacancy mechanism of diffusion. The results show that the high vacancy concentration and high concentration gradient of vacancies in the RE-aluminized processes are the main reason why the diffusion coefficient of Al atoms in RE-aluminizing is bigger than that in pure aluminizing.

  14. Muonium in Stishovite: Implications for the Possible Existence of Neutral Atomic Hydrogen in the Earth's Deep Mantle

    Science.gov (United States)

    Funamori, Nobumasa; Kojima, Kenji M.; Wakabayashi, Daisuke; Sato, Tomoko; Taniguchi, Takashi; Nishiyama, Norimasa; Irifune, Tetsuo; Tomono, Dai; Matsuzaki, Teiichiro; Miyazaki, Masanori; Hiraishi, Masatoshi; Koda, Akihiro; Kadono, Ryosuke

    2015-02-01

    Hydrogen in the Earth's deep interior has been thought to exist as a hydroxyl group in high-pressure minerals. We present Muon Spin Rotation experiments on SiO2 stishovite, which is an archetypal high-pressure mineral. Positive muon (which can be considered as a light isotope of proton) implanted in stishovite was found to capture electron to form muonium (corresponding to neutral hydrogen). The hyperfine-coupling parameter and the relaxation rate of spin polarization of muonium in stishovite were measured to be very large, suggesting that muonium is squeezed in small and anisotropic interstitial voids without binding to silicon or oxygen. These results imply that hydrogen may also exist in the form of neutral atomic hydrogen in the deep mantle.

  15. Rapid determination of major and minor elements in rare earth-cobalt magnets by inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Major and minor constituents, Sm, Ce, Y, Co, Fe, Mn, Cu, Zr and Hf, in typical rare earth-cobalt magnets were determined sequentially by inductively coupled plasma atomic emission spectrometry. Sample solutions were prepared by dissolving the magnets with aqua regia followed by dilution with 1.2 M HCl to suitable concentration. Beryllium was added as an internal standard in order to improved experimental accuracy and precision, and the emission intensity of Be was measured by using an additional small monochromator attached to the original instrument system. Cobalt, Fe, Cu and Zr in the magnets were also determined by conventional spectrophotometry. The results obtained by both methods were in good agreement with each other. (author)

  16. Alkaline quinone flow battery.

    Science.gov (United States)

    Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

    2015-09-25

    Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy. PMID:26404834

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

    Institute of Scientific and Technical Information of China (English)

    Jing Ping WANG; Jian Ru MA; Jing Yang NIU

    2006-01-01

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

  18. Synthesis, crystal and band structures, and optical properties of a new lanthanide-alkaline earth tellurium(IV) oxide: La2Ba(Te3O8)(TeO3)2

    International Nuclear Information System (INIS)

    A new quaternary lanthanide alkaline-earth tellurium(IV) oxide, La2Ba(Te3O8)(TeO3)2, has been prepared by the solid-state reaction and structurally characterized. The compound crystallizes in monoclinic space group C2/c with a=19.119(3), b=5.9923(5), c=13.2970(19) A, β=107.646(8)o, V=1451.7(3) A3 and Z=4. La2Ba(Te3O8)(TeO3)2 features a 3D network structure in which the cationic [La2Ba(TeO3)2]4+ layers are cross-linked by Te3O84- anions. Both band structure calculation by the DFT method and optical diffuse reflectance spectrum measurements indicate that La2Ba(Te3O8)(TeO3)2 is a wide band-gap semiconductor. - Graphical abstract: A new quaternary lanthanide alkaline-earth tellurium(IV) oxide, La2Ba(Te3O8)(TeO3)2, has been prepared by the solid-state reaction and structurally characterized. The structure of La2Ba(Te3O8)(TeO3)2 is 3D network in which the cationic [La2Ba(TeO3)2]4+ layers are cross-linked by Te3O84- anions. Both band structure calculation by the DFT method and optical diffuse reflectance spectrum measurements indicate that La2Ba(Te3O8)(TeO3)2 is a wide band-gap semiconductor

  19. Alkaline earth-gold-aluminides. Synthesis and structure of SrAu{sub 3}Al{sub 2}, SrAu{sub 2.83}Al{sub 2.17}, BaAu{sub 2.89}Al{sub 2.11} and BaAu{sub 7.09}Al{sub 5.91}

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Birgit; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2015-07-01

    New alkaline earth-gold-aluminides were synthesized from the elements in sealed tantalum or quartz ampoules in muffle furnaces at maximum annealing temperatures of 1325 K. The structures were refined from single crystal X-ray diffractometer data. SrAu{sub 3}Al{sub 2} crystallizes in an ordered version of the LT-SrZn{sub 5} structure: Pnma, a = 1315.9(3), b = 549.0(1), c = 684.5(3) pm, wR2 = 0.0232, 930 F{sup 2} values, 35 variables. SrAu{sub 2.83}Al{sub 2.17} (a = 1065.0(2), b = 845.0(2), c = 548.1(1) pm, wR2 = 0.0416, 452 F{sup 2} values, 22 variables) and BaAu{sub 2.89}Al{sub 2.11} (a = 1096.1(3), b = 835.7(3), c = 554.0(1) pm, wR2 = 0.0280, 501 F{sup 2} values, 22 variables) both adopt the BaZn{sub 5} type, space group Cmcm with Au/Al mixing on the 4c site. The gold and aluminum atoms in both types form three-dimensional networks of condensed tetrahedra with the strontium and barium atoms in large cavities. BaAu{sub 7.09}Al{sub 5.91} is a new member of the NaZn{sub 13} type: Fm anti 3c, a = 1257.6(2) pm, wR2 = 0.0267, 168 F{sup 2} values, 12 variables. Both the 96i and 8b sites show Au/Al mixing. The crystal chemical details are discussed.

  20. Semiempirical potentials for positron scattering by atoms

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Walters, H. R. J.; Arretche, Felipe; Dutra, Adriano; Mohallem, J. R. [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910, Vitoria, ES (Brazil); Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast, BT7 1NN (United Kingdom); Departamento de Fisica, Universidade do Estado de Santa Catarina, 89223-100, Joinville, SC (Brazil); Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, PO Box 702, 30123-970, Belo Horizonte, MG (Brazil)

    2011-08-15

    We report calculations of differential and integral cross sections for positron scattering by noble gas and alkaline-earth atoms within the same methodology. The scattering potentials are constructed by scaling adiabatic potentials so that their minima coincide with the covalent radii of the target atoms. Elastic differential and integral cross sections are calculated for Ne, Ar, Be, and Mg, and the results are very close to experimental and best theoretical data. Particularly, elastic differential cross sections for Be and Mg at low energies are reported.

  1. Adiabatic control of atomic dressed states for transport and sensing

    Science.gov (United States)

    Cooper, N. R.; Rey, A. M.

    2015-08-01

    We describe forms of adiabatic transport that arise for dressed-state atoms in optical lattices. Focusing on the limit of weak tunnel-coupling between nearest-neighbor lattice sites, we explain how adiabatic variation of optical dressing allows control of atomic motion between lattice sites: allowing adiabatic particle transport in a direction that depends on the internal state, and force measurements via spectroscopic preparation and readout. For uniformly filled bands these systems display topologically quantized particle transport. An implementation of the dressing scheme using optical transitions in alkaline-earth atoms is discussed as well as its favorable features for precise force sensing.

  2. Ion transport in alkaline and earth alkaline hydrogen fluorides

    NARCIS (Netherlands)

    Kroger, C; Niggemeier, H; Wiemhofer, HD; Glumov, O; Murin, [No Value

    2002-01-01

    The impedance of the hydrogen fluorides KHF2, NH4HF2 and BaHF3 was investigated as a function of temperature and in the presence of HF and H2O. A comparison of results on different electrode materials. (graphite, silver, palladium, Sn \\ SnF2, and Sn \\ SnF2 \\ LaF3) was used to elucidate the contribut

  3. Development of a simple method for the determination of lead in lipstick using alkaline solubilization and graphite furnace atomic absorption spectrometry.

    Science.gov (United States)

    Soares, Aline Rodrigues; Nascentes, Clésia Cristina

    2013-02-15

    A simple method was developed for determining the total lead content in lipstick samples by graphite furnace atomic absorption spectrometry (GFAAS) after treatment with tetramethylammonium hydroxide (TMAH). Multivariate optimization was used to establish the optimal conditions of sample preparation. The graphite furnace heating program was optimized through pyrolysis and atomization curves. An aliquot containing approximately 50mg of the sample was mixed with TMAH and heated in a water bath at 60°C for 60 min. Using Nb as the permanent modifier and Pd as the chemical modifier, the optimal temperatures were 900°C and 1800°C for pyrolysis and atomization, respectively. Under optimum conditions, the working range was from 1.73 to 50.0 μg L(-1), with detection and quantification limits of 0.20 and 0.34 μg g(-1), respectively. The precision was evaluated under conditions of repeatability and intermediate precision and showed standard deviations of 2.37%-4.61% and 4.93%-9.75%, respectively. The % recovery ranged from 96.2% to 109%, and no significant differences were found between the results obtained using the proposed method and the microwave decomposition method for real samples. Lead was detected in 21 tested lipstick samples; the lead content in these samples ranged from 0.27 to 4.54 μg g(-1). PMID:23598019

  4. Coordination of alkaline earth metal ions in the inverted cucurbit[7]uril supramolecular assemblies formed in the presence of [ZnCl4]2- and [CdCl4]2-.

    Science.gov (United States)

    Li, Qing; Zhang, Yun-Qian; Zhu, Qian-Jiang; Xue, Sai-Feng; Tao, Zhu; Xiao, Xin

    2015-05-01

    A convenient method to isolate inverted cucurbit[7]uril (iQ[7]) from a mixture of water-soluble Q[n]s was established by eluting the soluble mixture of Q[n]s on a Dowex (H(+) form) column so that iQ[7] could be selected as a ligand for coordination and supramolecular assembly with alkaline earth cations (AE(2+)) in aqueous HCl solutions in the presence of [ZnCl(4)](2-) and [CdCl(4)](2-) anions as structure-directing agents. Single-crystal X-ray diffraction analysis revealed that both iQ[7]-AE(2+) -[ZnCl(4)](2-) -HCl and iQ[7]-AE(2+) -[CdCl(4)](2-) -HCl interaction systems yielded supramolecular assemblies, in which the [ZnCl(4)](2-) and [CdCl(4)](2-) anions presented a honeycomb effect, and this resulted in the formation of linear iQ[7]/AE(2+) coordination polymers through outer-surface interactions of Q[n]s.

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

    International Nuclear Information System (INIS)

    The effect of high-energy (150 eV) electron irradiation in an electron microscope column on crystals of fluorides of alkaline earth elements CaF2, SrF2, and BaF2 is studied. During structural investigations by electron diffraction and electron microscopy, the electron irradiation causes chemical changes in MF2 crystals such as the desorption of fluorine and the accumulation of oxygen in the irradiated area with the formation of oxide MO. The fluorine desorption rate increases significantly when the electron-beam density exceeds the threshold value of ∼2 × 103 pA/cm2). In BaF2 samples, the transformation of BaO into Ba(OH)2 was observed when irradiation stopped. The renewal of irradiation is accompanied by the inverse transformation of Ba(OH)2 into BaO. In the initial stage of irradiation of all MF2 compounds, the oxide phase is in the single-crystal state with a lattice highly matched with the MF2 matrix. When the irradiation dose is increased, the oxide phase passes to the polycrystalline phase. Gaseous products of MF2 destruction (in the form of bubbles several nanometers in diameter) form a rectangular array with a period of ∼20 nm in the sample.

  6. [Treatment of chronic inflammation of the upper respiratory airways by inhalation thermal therapy with sulfur-sulfate-bicarbonate- carbonate-alkaline earth mineral water: a study of nasal cytology].

    Science.gov (United States)

    Cristalli, G; Abramo, A; Pollastrini, L

    1996-12-01

    The purpose of the paper is to better characterise changes occurred in nose cytology in a group of 50 subjects affected by chronic inflammation of upper respiratory airway. The patients were random shared in two groups: group A 40 subjects treated using sulphurous thermal water and a group B (control), 10 cases, treated using placebo saline solution. The post-therapy evaluation of nasal cytology showed an improvement of the chronic inflammation in 65% of group A patients (diminution of bacterial dust 65%, diminution of PMN cells in 60% of cases and disappearance of metaplasy notes in all the cases of group A. No statistical modifications were observed in control group. Moreover were observed a increase of plasma-cell number much more in group A. The author conclusion is that a period of thermal therapy using sulphur-sulphate-alkaline-earth metals water in chronic inflammation of the nose, throw pharmacological and physical actions, cause an improvement of the chronic inflammation and a normalisation of nose cytology. PMID:9381939

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kuad, P

    2006-01-15

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

  9. In-situ vaporization and matrix removal for the determination of rare earth impurities in zirconium dioxide by electrothermal vaporization inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    A novel method for the determination of trace rare earth impurities in ZrO2 powder has been developed based on electrothermal vaporization inductively coupled plasma atomic emission spectrometry. A polytetrafluoroethylene slurry was used as a fluorinating reagent to convert both the matrix (Zr) and the analytes (rare earth elements) into fluorides with different volatilities at a high temperature in a graphite furnace. The more volatile ZrF4 was removed in-situ by selective vaporization prior to the determination of the analytes, removing matrix spectral interferences. Under optimum operating conditions, the absolute detection limits of the analytes varied from 0.04 ng (Yb) to 0.50 ng (Pr) with relative standard deviations less than 5%. The recommended approach has been successfully applied to the determination of trace rare earth impurities (La, Pr, Eu, Gd, Ho and Yb) in ZrO2 powder and the results were in good agreement with those obtained by pneumatic nebulization inductively coupled plasma atomic emission spectrometry after the separation of the matrix using a solvent extraction procedure

  10. Mars Express/ASPERA-3/NPI and IMAGE/LENA observations of energetic neutral atoms in Earth and Mars orbit

    CERN Document Server

    Holmstrom, M; Barabash, S; Brinkfeldt, K; Moore, T E; Simpson, D

    2007-01-01

    The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed "unexplained neutral beams" unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a "secondary stream" having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0-1.57 AU as it is currently understood. In this paper we examine some highly suggestive similarities in the IMAG...

  11. Alkaline sorbent injection for mercury control

    Science.gov (United States)

    Madden, Deborah A.; Holmes, Michael J.

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  12. van der Waals coefficients for positronium interactions with closed-shell atoms

    CERN Document Server

    Swann, A R; Gribakin, G F

    2015-01-01

    The random-phase approximation with exchange (RPAE) is used with a $B$-spline basis to compute dynamic dipole polarizabilities of noble-gas atoms and several other closed-shell atoms (Be, Mg, Ca, Zn, Sr and Cd). From these, values of the van der Waals $C_6$ constants for positronium interactions with these atoms are determined and compared with existing data. Our best predictions of $C_6$ for Ps--noble-gas pairs are expected to be accurate to within 1%, and to within few per cent for the alkaline earths. Implications of increased $C_6$ values for more polarizable atoms are discussed.

  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. 碱锰电池用大功率无汞锌粉的雾化装置%Atomization device of high power mercury-free zinc powder for alkaline Zn/MnO2 battery

    Institute of Scientific and Technical Information of China (English)

    张健; 张杰

    2011-01-01

    设计了自由降落式喷嘴雾化装置,采用六孔啧料架,通过改进喷射孔间距、喷射角,降低雾化能耗,增加锌粉比表面积,提高碱锰电池的大功率性能.在0.8 MPa的气压下,获得粒径小于150μm的锌粉超过80%;不规则形态的锌粉比表面积达0.013 m2/g,体积平均粒径达141 μm.用该锌粉制备的LR6电池的1 500 mW、650 mW脉冲放电次数达130次.%A free fall nozzle atomization was designed. The device had a six hole ejection mechanism, by improving the ejection hole spacing and the ejection angle, the device decreased the atomization energy consumption,increased the specific surface area of the obtained zinc powder,which led to the improving of high power performance of the alkaline Zn/MnO2 battery.Over 80% of the zinc powder obtained at the pressure of 0.8 Mpa had a particle size less than 150 μm.The specific surface area of the zinc powder of irregular morphology reached to 0.013 m /g with an volume average particle size distribution of 141 μm.When pulse discharged with 1 500 mW,650 mW,the discharge times of LR6 battery produced by this zinc powder reached to 130.

  15. A study of the distribution of aluminium in human placental tissues based on alkaline solubilization with determination by electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Kruger, Pamela C; Schell, Lawrence M; Stark, Alice D; Parsons, Patrick J

    2010-09-01

    Aluminium (Al) is a nonessential element known to induce neurotoxic effects, such as dialysis dementia, in patients on hemodialysis, with compromised kidney function. The role of Al in the progression of some neurodegenerative diseases, such as Alzheimer's disease (AD), is controversial, and remains unclear. The effects of Al on other vulnerable populations, such as fetuses and infants, have been infrequently studied. In the present study, Al has been measured in human placenta samples, comprising ∼160 each of placenta bodies, placenta membranes, and umbilical cords, using electrothermal atomic absorption spectrometry (ETAAS) after atmospheric pressure digestion with tetramethylammonium hydroxide (TMAH) and ethylenediaminetetraacidic acid (EDTA). The sensitivity, or characteristic mass (m(0)), for Al at the 309.3-nm line was found to be 30 ± 4 pg. The instrumental detection limit (IDL) (3s) for Al in solution was calculated as 0.72 μg L(-1) while the method detection limit (MDL) (3s) was 0.25 μg g(-1). Accuracy was assessed through analysis of quality control (QC) materials, including certified reference materials (CRMs), in-house reference materials (RMs), and spike recovery experiments, of varying matrices. Placental tissue analyses revealed geometric mean concentrations of approximately 0.5 μg g(-1) Al in placenta bodies (n = 165) and membranes (n = 155), while Al concentrations in umbilical cords (n = 154) were about 0.3 μg g(-1). Al was detected in 95% of placenta bodies, and 81% of placenta membranes, but only in 46% of umbilical cords.

  16. ALP (Alkaline Phosphatase) Test

    Science.gov (United States)

    ... Also known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on ...

  17. Determination of yttrium and rare-earth elements in rocks by graphite-furnace atomic-absorption spectrometry.

    Science.gov (United States)

    Gupta, J G

    1981-01-01

    With use of synthetic solutions and several international standard reference materials a method has been developed for determining traces of Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in rocks by electrothermal atomization in a pyrolytically-coated graphite furnace. Depending on the element, the sensitivity is of the order of 10(-9)-10(-12) g at 2500 degrees . To avoid matrix interferences the lanthanides are separated from the common elements by co-precipitation with calcium and iron as carriers. The data for Canadian reference rock SY-2 (syenite), U.S.G.S. reference rocks W-2 (diabase), DNC-1 (diabase) and BIR-1 (basalt), and South African reference rock NIM-18/69 (carbonatite) obtained by graphite-furnace atomization are compared with the values obtained by flame atomic-absorption. The results are in good agreement with literature values. PMID:18962852

  18. MULTIPHOTON IONIZATION OF ATOMS

    OpenAIRE

    Mainfray, G.

    1985-01-01

    Multiphoton ionization of one-electron atoms, such as atomic hydrogen and alkaline atoms, is well understood and correctly described by rigorous theoretical models. The present paper will be devoted to collisionless multiphoton ionization of many-electron atoms as rare gases. It induces removal of several electrons and the production of multiply charged ions. Up to Xe5+ ions are produced in Xe atoms. Doubly charged ions can be produced, either by simultaneous excitation of two electrons, or b...

  19. Positron elastic scattering from alkaline earth targets

    Science.gov (United States)

    Poveda, Luis A.; Assafrão, Denise; Mohallem, José R.

    2016-07-01

    A previously reported model potential approach [Poveda et al., Phys. Rev. A 87, 052702 (2013)] was extended to study low energy positron elastic scattering from beryllium and magnesium. The cross sections were computed for energies ranging from 10-5 eV up to well above the positronium formation threshold. The present results are in good agreement with previous reports, including the prediction of a p-wave resonance in the cross section for magnesium. The emergence of this shape resonance is connected to a trend observed in the evolution of the partial wave cross section in going from Be to Mg target. This trend lead us to speculate that a sharp d-wave resonance should be observed in positron elastic scattering from calcium. The positron-target binding energies are investigated in detail, both using the scattering information and by direct computation of the bound state energies using the model potentials. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2016-70120-y

  20. Alkaline earth stannates: The next silicon?

    International Nuclear Information System (INIS)

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

  1. Alkaline earth stannates: The next silicon?

    Directory of Open Access Journals (Sweden)

    Sohrab Ismail-Beigi

    2015-06-01

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

  2. Alkaline earth stannates: The next silicon?

    OpenAIRE

    Sohrab Ismail-Beigi; Walker, Frederick J.; Sang-Wook Cheong; Rabe, Karin M.; Ahn, Charles H.

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    I. Ssemmanda

    2012-03-01

    Full Text Available For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120–9336 μg g−1 as well as for Sr (9–2150 μg g−1. Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3–1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel

  4. Enhanced Magnetic Trap Loading for Atomic Strontium

    CERN Document Server

    Barker, D S; Pisenti, N C; Campbell, G K

    2015-01-01

    We report on a technique to improve the continuous loading of atomic strontium into a magnetic trap from a Magneto-Optical Trap (MOT). This is achieved by adding a depumping laser tuned to the 3P1 to 3S1 (688-nm) transition. The depumping laser increases atom number in the magnetic trap and subsequent cooling stages by up to 65 % for the bosonic isotopes and up to 30 % for the fermionic isotope of strontium. We optimize this trap loading strategy with respect to the 688-nm laser detuning, intensity, and beam size. To understand the results, we develop a one-dimensional rate equation model of the system, which is in good agreement with the data. We discuss the use of other transitions in strontium for accelerated trap loading and the application of the technique to other alkaline-earth-like atoms.

  5. Decomposition kinetics of alkaline earth carbonates by integral approximation method Cinética de decomposição de carbonatos de terra alcalina pelo método de aproximação integral

    Directory of Open Access Journals (Sweden)

    S. Maitra

    2008-09-01

    Full Text Available The decomposition kinetics of four synthetic alkaline earth metal carbonates (MgCO3, CaCO3, SrCO3 and BaCO3 was studied under non-isothermal conditions from thermo-gravimetric measurements as compared to. The integral approximation method of Coats and Redfern was used to determine the kinetic parameters for the decomposition processes. The decomposition reactions followed mostly first order kinetics and the activation energy of the decomposition reactions increased with the increase in the molecular mass of the carbonates. The change in enthalpy for the decomposition processes was also calculated and compared with the activation energies for the decomposition processes. The activation energy of the decomposition process for all the carbonates was higher than the enthalpy of the reaction excepting SrCO3.A cinética de decomposição de quatro carbonatos sintéticos de metais de terra alcalina (MgCO3, CaCO3, SrCO3 e BaCO3 foi estudada sob condições não isotérmicas por meio de medidas de termogravimétricas e feita sua comparação. O método de aproximação integral de Coats e Redfern foi usado para determinar os parâmetros cinéticos dos processos de decomposição. As reações de decomposição seguiram principalmente cinética de primeira ordem e a energia de ativação para as reações de decomposição aumentou com o aumento da massa molecular dos carbonatos. A variação na entalpia para os processos de decomposição foi também calculada e comparada com as energias de ativação. A energia de ativação dos processos de decomposição de todos os carbonatos foi maior que a entalpia da reação excepto para SrCO3.

  6. 中温商业SCR催化剂碱和碱土中毒特性研究%Study on alkali and alkaline earths poisoning characteristics for a commercial SCR catalyst

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 卢凤菊; 高兰君; 岳时吉

    2016-01-01

    The poisoning of a commercial selective catalytic reduction ( SCR ) catalysts by alkali ( K ) and alkaline earths ( Ca) has been simulated in the laboratory. The techniques of N2 adsorption, scanning electronic microscopy, X-ray photoelectron spectroscopy, NH3-temperature program desorption, H2-temperature program reduction were used to identify the changes of physical chemical characteristics of the catalysts before and after the simulated poisoning. The results indicated that the poisoning of K and Ca did not damage the basic pore structure of the SCR catalyst, but decreased the BET surface area and pore volume. The poisoning by K and Ca changed the chemical valence state of V and decreased the reducibility of V. The poisoning by K and Ca decreased the amount of chemically adsorbed oxygen on the catalyst surface as well as acidity of the catalysts. The poisoning by K and Ca lowered the SCR activity of the catalysts and the poisoning by Ca was more serious than K.%在实验室条件下对选择性催化还原( SCR)商业催化剂的碱( K)和碱土( Ca)中毒进行了模拟,并采用液氮吸附、扫描电镜、能谱分析、NH3-程序升温脱附、H2-程序升温还原等方法对催化剂中毒前后的物理化学性质变化进行了表征。结果表明, K和Ca的中毒没有破坏商业中温SCR催化剂孔的基本结构,但K和Ca的中毒使催化剂的比表面积和孔容减小。 K和Ca的中毒在一定程度上改变了催化剂表面钒的价态,导致了钒的还原能力减弱,同时降低催化剂表面化学吸附氧。钾中毒和钙中毒使催化剂的表面酸量降低。钾和钙中毒造成中温SCR催化剂的脱硝活性降低,并且Ca中毒造成的催化剂活性降低要明显高于K中毒。

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

    Directory of Open Access Journals (Sweden)

    I. Ssemmanda

    2012-11-01

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

  8. Modifications of Schr\\"{o}dinger's Equation Complying with the Effect of Earth's Rotation on Quantum Energy in Atoms and with the Electromagnetic Force

    CERN Document Server

    Su, C C

    2002-01-01

    Recently, we have presented a local-ether wave equation incorporating a nature frequency and the electric scalar potential, from which the speed-dependences in the angular frequency and wavelength of matter wave, in the mass of particle, and in the energy of quantum states are derived. These relations look like the postulates of de Broglie and the Lorentz mass-variation law, except that the particle speed is referred specifically to a geocentric inertial frame and hence incorporates earth's rotation for earthbound particles. Further, the wave equation is extended by connecting the scalar potential to the augmentation operator which is associated with a velocity difference between involved particles. Then the electromagnetic force law is derived, which under some ordinary conditions reduces to the modified Lorentz force law. In this investigation, the interaction of atoms with electromagnetic radiation is explored. Then it is shown that the time evolution equation derived from the wave equation is substantiall...

  9. Magnetocaloric effect of RM2 (R = rare earth, M = Ni, Al) intermetallic compounds made by centrifugal atomization process for magnetic refrigerator

    Science.gov (United States)

    Matsumoto, K.; Asamato, K.; Nishimura, Y.; Zhu, Y.; Abe, S.; Numazawa, T.

    2012-12-01

    RM2 (R = rare earth, M = Al, Ni and Co) compounds have large entropy change and magnetic transition temperatures can be controlled by change of R and/or M so that are suitable to a magnetic refrigerator for hydrogen liquefaction under development. In order to improve refrigerator performance, spherical powdered HoAl2, DyAl2, and GdNi2 compounds with submillimeter diameter were synthesized by centrifugal atomization process. By measuring the magnetization and heat capacity, we obtained entropy change by magnetic fields and entropy as functions of temperature and magnetic field, which are essential for analysing the magnetic refrigeration cycle. All samples showed sharp magnetic transitions and had good potentials for use in magnetic refrigeration.

  10. Magnetocaloric effect of RM2 (R = rare earth, M = Ni, Al) intermetallic compounds made by centrifugal atomization process for magnetic refrigerator

    International Nuclear Information System (INIS)

    RM2 (R = rare earth, M = Al, Ni and Co) compounds have large entropy change and magnetic transition temperatures can be controlled by change of R and/or M so that are suitable to a magnetic refrigerator for hydrogen liquefaction under development. In order to improve refrigerator performance, spherical powdered HoAl2, DyAl2, and GdNi2 compounds with submillimeter diameter were synthesized by centrifugal atomization process. By measuring the magnetization and heat capacity, we obtained entropy change by magnetic fields and entropy as functions of temperature and magnetic field, which are essential for analysing the magnetic refrigeration cycle. All samples showed sharp magnetic transitions and had good potentials for use in magnetic refrigeration.

  11. Atom-efficient regioselective 1,2-dearomatization of functionalized pyridines by an earth-abundant organolanthanide catalyst

    Science.gov (United States)

    Dudnik, Alexander S.; Weidner, Victoria L.; Motta, Alessandro; Delferro, Massimiliano; Marks, Tobin J.

    2014-12-01

    Developing earth-abundant, non-platinum metal catalysts for high-value chemical transformations is a critical challenge to contemporary chemical synthesis. Dearomatization of pyridine derivatives is an important transformation to access a wide range of valuable nitrogenous natural products, pharmaceuticals and materials. Here, we report an efficient 1,2-regioselective organolanthanide-catalysed pyridine dearomatization process using pinacolborane, which is compatible with a broad range of pyridines and functional groups and employs equimolar reagent stoichiometry. Regarding the mechanism, derivation of the rate law from NMR spectroscopic and kinetic measurements suggests first order in catalyst concentration, fractional order in pyridine concentration and inverse first order in pinacolborane concentration, with C=N insertion into the La-H bond as turnover-determining. An energetic span analysis affords a more detailed understanding of experimental activity trends and the unusual kinetic behaviour, and proposes the catalyst ‘resting’ state and potential deactivation pathways.

  12. Theory of a metrology for the earths magnetic field based on the resonance of polarised atomic nuclei (1962)

    International Nuclear Information System (INIS)

    The problems presented by the metrology of the earths field are studied from two points of view. a. The first, purely physical, concerns the study of NMR transducers in their role for the transformation of the magnetic field into a frequency. The possibilities and limitations are outlined. The use of an equivalent model is introduced systematically in the considerations of NMR phenomena, this makes it possible to treat all problems of interaction between a spin system and an electric detection system in a unified form. b. The other point of view concerns the restitution of the nuclear signal frequency in the form of a directly perceptible observable. The treatment of information is considered from a statistical angle, which leads to the study of an optimisation process concerning the linearization of the measurement as well as the minimisation of noise effects. (author)

  13. Microstructual investigation of mixed rar earth iron boron processed vis melt-spinning and high-pressure gas-atomization for isotrophic bonded permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Buelow, Nicholas Lee

    2005-08-01

    A solid solution of three rare earths (RE) in the RE{sub 2}Fe{sub 14}B structure have been combined to create the novel mixed rare earth iron boron (MRE{sub 2}Fe{sub 14}B) alloy family. MRE{sub 2}Fe{sub 14}B exhibits reduced temperature dependent magnetic properties; remanence and coercivity. The desired form of MRE{sub 2}Fe{sub 14}B is a powder that can be blended with a polymer binder and compression or injection molded to form an isotropic polymer bonded permanent magnet (PBM). Commercially, Nd{sub 2}Fe{sub 14}B is the alloy of choice for PBMs. Powders of Nd{sub 2}Fe{sub 14}B are made via melt-spinning as can be MRE{sub 2}Fe{sub 14}B which allows for direct comparisons. MRE{sub 2}Fe{sub 14}B made using melt-spinning at high wheel speeds is overquenched and must be annealed to an optimal hard magnetic state. Due to the rare earth content in the MRE{sub 2}Fe{sub 14}B powders, they must be protected from the environment in which they operate. This protection is accomplished by using a modified fluidized bed process to grow a protective fluoride coating nominally 15nm thick, to reduce air oxidation. MRE{sub 2}Fe{sub 14}B has demonstrated reduced temperature dependent magnetic properties in ribbon and PBM form. The real challenge has been modifying alloy designs that were successfully melt-spun to be compatible with high-pressure gas-atomization (HPGA). The cooling rates in HPGA are lower than melt-spinning, as the powders are quenched via convective cooling, compared to melt-spinning, which quenches initially by conductive cooling. Early alloy designs, in gas atomized and melt-spun form, did not have similar phase compositions or microstructures. Alloy additions, such as the addition of zirconium as a nucleation catalyst, were successful in creating similar phases and microstructures in the HPGA powders and melt-spun ribbon of the same MRE{sub 2}Fe{sub 14}B composition.

  14. 稀土原子与离子的自然辐射寿命测量%Natural radiative lifetime measurements of rare-earth atoms and ions

    Institute of Scientific and Technical Information of China (English)

    蒋红玫; 杨博思; 李贺龙; 徐淮良

    2013-01-01

    Advances in the techniques available for natural radiative lifetime measurement of excited states of free atoms and ions are presented.The disadvantages and advantages of several often-used methods for radia-tive lifetime measurements of free atoms and ions of rare-earth elements are reviewed by taking La Ⅰ and PrⅡas examples.Then, the techniques of the laser ablation to produce free atoms and ions are introduced by taking SmⅡas an example, and the time-resolved laser induced fluorescence (LIF) spectroscopy for the radi-ative lifetime measurements is discussed in detail .The limitation of this method of LIF combined with laser ab-lation is summarized and a possibly useful solution is suggested , which may be helpful to further improve the precision of radiative lifetime measurements.%概述了当前自由原子和离子的激发态自然辐射寿命测量技术的进展。以LaⅠ和Pr Ⅱ为例,系统介绍了几种稀土元素自由原子和离子激发态寿命测量技术并分析了它们的优缺点;以Sm Ⅱ为例,详细介绍了激光烧蚀产生自由原子(离子)技术及结合激光诱导荧光时间分辨光谱技术进行激发态寿命测量的优缺点。最后,探讨了改进上述技术局限性的解决思路,以期进一步提高辐射寿命测量的精确度。

  15. Formation of molecular ions by radiative association of cold trapped atoms and ions

    OpenAIRE

    Silva Jr, Humberto Da; Raoult, Maurice; Aymar, Mireille; Dulieu, Olivier

    2015-01-01

    Radiative emission during cold collisions between trapped laser-cooled Rb atoms and alkaline-earth ions (Ca$^+$, Sr$^+$, Ba$^+$) and Yb$^+$, and between Li and Yb$^+$, are studied theoretically, using accurate effective-core-potential based quantum chemistry calculations of potential energy curves and transition dipole moments of the related molecular ions. Radiative association of molecular ions is predicted to occur for all systems with a cross section two to ten times larger than the radia...

  16. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  17. Alkaline "Permanent" Paper.

    Science.gov (United States)

    Pacey, Antony

    1991-01-01

    Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and recyclability is…

  18. Inlfuence of Mixed Alkali-Alkaline Earth Effect on Alkali Resistance of Medium Temperature Fritted Glaze%混合碱/碱土金属效应对中温熔块釉耐碱性的影响

    Institute of Scientific and Technical Information of China (English)

    秦立邦; 卢希龙; 曹春娥; 陈云霞; 沈华荣; 黄钢

    2014-01-01

    In order to improve the alkali resistance of medium temperature fritted glaze, a large number of experiments were carried out to get a better base fritted glaze. Then, inlfuence of mixed alkali metal effect and mixed alkaline earth metal effect on alkali resistance of the glaze was studied. Results show that mixed alkali effect existed in two alkali metal oxides-Li2O and Na2O. When the Li+/Na+molar ratio was equal to 1, the frit had the best alkali resistance. Calcium oxide had obvious suppression effect on alkali metal oxides. When the CaO/(Li2O+Na2O) molar ratio was equal to 1.22, the frit had the best alkali resistance. For binary mixed alkali metal oxides, when both the molar ratios of CaO/BaO and CaO/MgO were equal to 8.2, the frit had the best alkali resistance, but BaO worked better than MgO. For ternary mixed alkali metal oxides, when the molar ratio of CaO:MgO:BaO was equal to 14:3.3:1, both the frit and fritted glaze had the best alkali resistance.%为了提高中温熔块釉的耐碱性,通过大量实验得到较好的基础熔块釉组成,在此基础上,探讨混合碱金属效应、混合碱土金属效应对熔块耐碱性的影响。结果表明:Li2O和Na2O两种碱金属氧化物存在“混合碱金属效应”,其摩尔比为1时,熔块耐碱性最佳。氧化钙对碱金属(Li2O+Na2O)的压制效应明显,当CaO/(Li2O+Na2O)为1.22时,熔块耐碱性最好。二元碱土金属混合时,CaO/BaO、CaO/MgO摩尔比均为8.2时耐碱性最好,但BaO的效果要大于MgO;三元碱土混合中, CaO∶MgO∶BaO摩尔比为14∶3.3∶1时,熔块耐碱性最高,且此时釉的耐碱性也最强。

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

    Energy Technology Data Exchange (ETDEWEB)

    Durand, S

    1999-07-01

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

  20. Alkaline battery operational methodology

    Energy Technology Data Exchange (ETDEWEB)

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  1. Uranium in alkaline rocks

    International Nuclear Information System (INIS)

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

  2. Uranium in alkaline rocks

    Energy Technology Data Exchange (ETDEWEB)

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

    1978-04-01

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

  3. Atomic structures of 13-atom clusters by density functional theory

    Science.gov (United States)

    Chen, Hsin-Yi; Wei, Ching-Ming

    2007-03-01

    The 13-atom cluster structures of the alkaline metals, alkaline earth metals, boron group, 3d, 4d, and 5d transition metals in the periodic table, and Pb are investigated by density functional theory with three kinds of exchange correlation approximation: i) LDA (Local Density Approximation), ii) GGA (Generalized Gradient Approximation) [1], and iii) PBE (Perdew-Burke-Ernzerhof) [2]. The results mainly focus on five 3-D structures: icosahedral, cuboctahedral, hexagonal-closed packed, body-center cubic, decahedral, and the other two layer structures: buckled biplanar (bbp) and garrison-cap biplanar (gbp) structures. Limited by accuracy of exchange correlation approximation, two interesting results are found. The ground states of Ca13, Sr13, Ba13, Sc13, Y13, La13, Ti13, Zr13, and Hf13 are icosahedral structures. The clusters of Ir13, Pt13, Cu13, Ag13, and Au13 are more favorable for layer structures (i.e. bbp and gbp) than the other five 3-D structures. [1] J. P. Perdew et al., Phys. Rev. B 46, 6671 (1992). [2] J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996).

  4. Atomic Quantum Simulation of U(N) and SU(N) Non-Abelian Lattice Gauge Theories

    OpenAIRE

    Banerjee D.; Bogli M.; Dalmonte M.; Rico E.; Stebler P.; Wiese U.-J.; Zoller P.

    2012-01-01

    Using ultracold alkaline-earth atoms in optical lattices, we construct a quantum simulator for U(N) and SU(N) lattice gauge theories with fermionic matter based on quantum link models. These systems share qualitative features with QCD, including chiral symmetry breaking and restoration at non-zero temperature or baryon density. Unlike classical simulations, a quantum simulator does not suffer from sign problems and can address the corresponding chiral dynamics in real time.

  5. Reviews Opera: Doctor Atomic DVD: Doctor Atomic Equipment: Digital stopclock with external trigger Book: I Cyborg Book: Flat Earth: The History of an Infamous Idea Book: Mere Thermodynamics Book: CGP revision guides Book: Hiding the Elephant: How Magicians Invented the Impossible Book: Back of the Envelope Physics Web Watch

    Science.gov (United States)

    2009-07-01

    WE RECOMMEND Doctor Atomic The new Doctor Atomic opera provkes discussion on ethics I Cyborg The world's first human cyborg shares his life story in I Cyborg Flat Earth: The History of an Infamous Idea Flat Earth gives us a different perspective on creationism Mere Thermodynamics An introductory text on the three laws CGP revision guides This revision guide suits all courses and every pocket Hiding the Elephant: How Magicians Invented the Impossible The mystery of many illusions are solved in this book Back of the Envelope Physics This reference deserves a place on your bookshelf WORTH A LOOK Doctor Atomic The DVD doesn't do justice to the live performance Digital stopclock with external trigger Use these stopclocks when you need an external trigger WEB WATCH Webcasts reach out to an online audience

  6. Resolved atomic interaction sidebands in an optical clock transition

    CERN Document Server

    Bishof, Michael; Swallows, Matthew D; Gorshkov, Alexey V; Ye, Jun; Rey, Ana Maria

    2011-01-01

    We report the observation of resolved atomic interaction sidebands (ISB) in the ${}^{87}$Sr optical clock transition when atoms at microkelvin temperatures are confined in a two-dimensional (2D) optical lattice. The ISB are a manifestation of the strong interactions that occur between atoms confined in a quasi-one-dimensional geometry and disappear when the confinement is relaxed along one dimension. The emergence of ISB is linked to the recently observed suppression of collisional frequency shifts in [1]. At the current temperatures, the ISB can be resolved but are broad. At lower temperatures, ISB are predicted to be substantially narrower and usable as powerful spectroscopic tools in strongly interacting alkaline-earth gases.

  7. Atomic jet with ionization detection for laser spectroscopy of Rydberg atoms under collisions and fields

    Science.gov (United States)

    Philip, G.

    2008-03-01

    An efficient atomic jet setup offering many unprecedented advantages over a conventional heat pipe setup used in multi-photon spectroscopy, mainly of alkaline-earth metals, has been constructed by a scheme in which the sample material is encapsulated in a disposable cartridge oven located inside a thermally stabilised heat-pipe and is made to effuse in to a row of atomic beams merging to form a jet target. This novel scheme combines the advantages of both high density atomic beam with convenient geometry for orthogonal excitation and high sensitive ionisation detection capabilities of thermionic diodes, besides eliminating several problems inherent in the usual heat-pipe operation. Out of various designs, typical results are presented for a linear heat-pipe with vertical atomic jet used in two-photon spectroscopy of highly excited states of Sr I. Controlled excitations of both Rydberg and non-Rydberg states, which cannot otherwise be accessed from the ground state due to parity and spectroscopic selection rules, have been achieved by employing a weak electric field complimented by collisions. The atomic jet setup is also found very useful for the study of collisional broadening and shift of excited states and time evolution of Rydberg atoms.

  8. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  9. 流量对接地极雾化电晕放电油烟净化器的影响%Influence of Water Flow on Coking Fume Purifier With Earthed Atomizing Corona Discharges

    Institute of Scientific and Technical Information of China (English)

    米俊锋; 董美; 杜胜男; 袁广娇

    2011-01-01

    研究了在接地极雾化电晕放电中流量对起晕电压的影响,估算了不同流量下泰勒锥尖端的曲率.研究结果表明:随流量的变化起晕电压存在一个最小值,说明此时形成的泰勒锥尖端曲率半径最小.同时,分析了泰勒锥沿线电极的分布及其对净化效率的影响,测量了接地极雾化电晕放电过程中形成的雾化液滴的粒径并分析了其形成过程.结果表明粒径分布相对集中.其原因可能是:液滴粒径的大小主要受电场力和水流的平均带电量的影响,从液滴粒径的分布来看,也说明水层在接触带电和感应带电后形成了尖端曲率半径较为相似的泰勒锥,所以尖端积累的电荷量也比较接近,最后在电场力以及泰勒锥尖端电荷间排斥力的作用下,形成了粒径大小比较集中的液滴.%The influence of magnetic field on corona onset voltage was studied in the earthed atomizing corona discharge, and the curvature of the charging mechanism was studied in earthed atomizing corona discharge under magnetic field or not. Eventually, the charging mechanism of earthed atomizing discharges under magnetic field was analyzed. The results show that the corona onset voltage of the earthed atomizing corona discharge is decreased because the magnetic field is used, and the charging efficiency is enhanced by magnetic field. But the influence on the diameter of water drops is not obvious. In addition, the minimum values of discharge currents are exist in the earthed atomizing corona discharge when the magnetic field is used or not.

  10. Atomizing nozzle and process

    Science.gov (United States)

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1992-06-30

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  11. Development of a high flow source of energetic oxygen atoms for material degradation studies. [of Space Shuttles in low earth orbit environments

    Science.gov (United States)

    Caledonia, G. E.; Krech, R. H.

    1985-01-01

    A technique for the generation, in the laboratory, of thermally 'cold', high flux of energetic oxygen atoms is presented. The flux of nearly mono-energetic oxygen atoms is obtained after a laser-induced breakdown of oxygen molecules followed by a rapid expansion of the recombining plasma. The experimental apparatus, the optical and spectral measurements, the O-atom source characterization, and the material degradation studies are discussed. Average oxygen atom velocities of about 5 to 13 km/s are measured with an estimated flux of 10 to the 18th per pulse, over pulse durations of several microseconds. The flow of the O2 gas for about 200 microseconds before applying the laser pulse is found to give best results. It is also found that the energetic O-atom irradiation of sample targets such as Al, Fe, and polyethylene, induces mass removal. In addition, spectral scans of the radiation reveals the existence of two main spectral subsets.

  12. 电感耦合等离子体原子发射光谱法同时测定饮用水的硬度和碱度%Simultaneous determination of the hardness and alkalinity in drinking water by inductively coupled plasma atomic emission spectrometry

    Institute of Scientific and Technical Information of China (English)

    霍建中; 段旭川

    2013-01-01

    The feasibility of simultaneous determination of hardness and alkalinity of drinking water by inductively coupled plasma atomic emission spectrometry (ICP-AES) was studied.the water sample was acidified off-line with diluted hydrochloric acid.The bicarbonates in water sample were in-situ converted into carbon dioxide,which was also dissolved in original water.Then,the solution was sampled by conventional single tube of inductively coupled plasma atomic emission spectrometer.The simultaneous sampling of CO2,Ca and Mg was realized at relatively low atomizer pressure.Among them,CO2 was sampled in gas state,while Ca and Mg were sampled in atomizing state.In this study,the bicarbonates with low sampling efficiency in atomizing method were converted into gas carbon dioxide,which had high sampling efficiency,thus the determination sensitivity of carbon was increased,realizing the accurate determination.The measured content of inorganic carbon was converted to the content of bicarbonates,so the alkalinity of drinking water was obtained.Meanwhile,the content of Ca and Mg was converted to the content of calcium carbonate to calculate the hardness of water.Under the optimal experimental conditions,i.e.,atomizer pressure of 241.3 kPa and dilution ratio of 5for water sample,the hardness and alkalinity of drinking water were simultaneously determined by this method.The found results were consistent with those obtained by titration method.%研究了使用电感耦合等离子体原子发射光谱法(ICP-AES)同时测定饮用水的硬度和碱度可行性.通过用稀盐酸离线酸化水样,使水样中的碳酸氢根原位转化为二氧化碳并继续溶解在原水中,然后使用ICP-AES仪器上常规的单管吸取溶液,在比较低的雾化器压力下实现了CO2、Ca、Mg的同时进样.其中CO2属于气态进样,而钙、镁属于雾化进样.由于方法将雾化法进样效率低的碳酸氢根转化成进样效率高的二氧化碳气态,因此碳的测定灵敏

  13. A novel methodology for rapid digestion of rare earth element ores and determination by microwave plasma-atomic emission spectrometry and dynamic reaction cell-inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Helmeczi, Erick; Wang, Yong; Brindle, Ian D

    2016-11-01

    Short-wavelength infrared radiation has been successfully applied to accelerate the acid digestion of refractory rare-earth ore samples. Determinations were achieved with microwave plasma-atomic emission spectrometry (MP-AES) and dynamic reaction cell - inductively coupled plasma-mass spectrometry (DRC-ICP-MS). The digestion method developed was able to tackle high iron-oxide and silicate matrices using only phosphoric acid in a time frame of only 8min, and did not require perchloric or hydrofluoric acid. Additionally, excellent recoveries and reproducibilities of the rare earth elements, as well as uranium and thorium, were achieved. Digestions of the certified reference materials OREAS-465 and REE-1, with radically different mineralogies, delivered results that mirror those obtained by fusion processes. For the rare-earth CRM OKA-2, whose REE data are provisional, experimental data for the rare-earth elements were generally higher than the provisional values, often exceeding z-values of +2. Determined values for Th and U in this reference material, for which certified values are available, were in excellent agreement. PMID:27591646

  14. Realizing exactly solvable SU (N ) magnets with thermal atoms

    Science.gov (United States)

    Beverland, Michael E.; Alagic, Gorjan; Martin, Michael J.; Koller, Andrew P.; Rey, Ana M.; Gorshkov, Alexey V.

    2016-05-01

    We show that n thermal fermionic alkaline-earth-metal atoms in a flat-bottom trap allow one to robustly implement a spin model displaying two symmetries: the Sn symmetry that permutes atoms occupying different vibrational levels of the trap and the SU (N ) symmetry associated with N nuclear spin states. The symmetries make the model exactly solvable, which, in turn, enables the analytic study of dynamical processes such as spin diffusion in this SU (N ) system. We also show how to use this system to generate entangled states that allow for Heisenberg-limited metrology. This highly symmetric spin model should be experimentally realizable even when the vibrational levels are occupied according to a high-temperature thermal or an arbitrary nonthermal distribution.

  15. Alkaline Phosphatase in Stem Cells

    Directory of Open Access Journals (Sweden)

    Kateřina Štefková

    2015-01-01

    Full Text Available Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. In humans and other mammals, determinations of the expression and activity of alkaline phosphatase have frequently been used for cell determination in developmental studies and/or within clinical trials. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail. First, we briefly summarize contemporary knowledge of mammalian alkaline phosphatases in general. Second, we focus on the known facts of its role in and potential significance for the identification of stem cells.

  16. Narrow-line magneto-optical cooling and trapping of strongly magnetic atoms

    CERN Document Server

    Berglund, Andrew J; McClelland, Jabez J

    2008-01-01

    Laser cooling on weak transitions is a useful technique for reaching ultracold temperatures in atoms with multiple valence electrons. However, for strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT) is destabilized by competition between optical and magnetic forces. We overcome this difficulty in Er by developing an unusual narrow-line MOT that balances optical and magnetic forces using laser light tuned to the blue side of a narrow (8 kHz) transition. The trap population is spin-polarized with temperatures reaching below 2 microkelvin. Our results constitute an alternative method for laser cooling on weak transitions, applicable to rare-earth-metal and metastable alkaline earth elements.

  17. Alkaline fuel cells applications

    Science.gov (United States)

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

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

  18. A Comparison of Atomic Oxygen Erosion Yields of Carbon and Selected Polymers Exposed in Ground Based Facilities and in Low Earth Orbit

    Science.gov (United States)

    Rutledge, Sharon K.; Banks, Bruce A.; Cales, Michael

    1994-01-01

    A comparison of the relative erosion yields (volume of material removed per oxygen atom arriving) for FEP Teflon, polyethylene, and pyrolytic graphite with respect to Kapton HN was performed in an atomic oxygen directed beam system, in a plasma asher, and in space on the EOIM-III (Evaluation of Oxygen Interaction with Materials-III) flight experiment. This comparison was performed to determine the sensitivity of material reaction to atomic oxygen flux, atomic oxygen fluence, and vacuum ultraviolet radiation for enabling accurate estimates of durability in ground based facilities. The relative erosion yield of pyrolytic graphite was found not to be sensitive to these factors, that for FEP was sensitive slightly to fluence and possibly ions, and that for polyethylene was found to be partially VUV and flux sensitive but more sensitive to an unknown factor. Results indicate that the ability to use these facilities for material relative durability prediction is great as long as the sensitivity of particular materials to conditions such as VUV, and atomic oxygen flux and fluence are taken into account. When testing materials of a particular group such as teflon, it may be best to use a witness sample made of a similar material that has some available space data on it. This would enable one to predict an equivalent exposure in the ground based facility.

  19. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  20. Bifunctional alkaline oxygen electrodes

    Science.gov (United States)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  1. Silica in alkaline brines

    Science.gov (United States)

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  2. An alkaline element

    Energy Technology Data Exchange (ETDEWEB)

    Arita, T.; Murakami, K.; Okha, K.

    1983-04-28

    A cathode with a dual layer active mass is installed in the disk shaped alkaline silver and zinc element. The first layer, which is turned towards the anode, contains 85 parts Ag2O, 5 parts electrolytic MnO2 and 10 parts graphite. The second layer, which contacts the bottom of the element, contains 35 parts Ag2O, 60 parts electrolytic MnO2 and 5 parts graphite. The electrical capacity of the first and second layers is 60 and 40, respectively. The first layer may be discharged with a high current density and the second layer with less current density. The element has high characteristics with comparatively low cost.

  3. Atomic Oxygen Effects

    Science.gov (United States)

    Miller, Sharon K. R.

    2014-01-01

    Atomic oxygen, which is the most predominant species in low Earth orbit, is highly reactive and can break chemical bonds on the surface of a wide variety of materials leading to volatilization or surface oxidation which can result in failure of spacecraft materials and components. This presentation will give an overview of how atomic oxygen reacts with spacecraft materials, results of space exposure testing of a variety of materials, and examples of failures caused by atomic oxygen.

  4. Modulators of intestinal alkaline phosphatase.

    Science.gov (United States)

    Bobkova, Ekaterina V; Kiffer-Moreira, Tina; Sergienko, Eduard A

    2013-01-01

    Small molecule modulators of phosphatases can lead to clinically useful drugs and serve as invaluable tools to study functional roles of various phosphatases in vivo. Here, we describe lead discovery strategies for identification of inhibitors and activators of intestinal alkaline phosphatases. To identify isozyme-selective inhibitors and activators of the human and mouse intestinal alkaline phosphatases, ultrahigh throughput chemiluminescent assays, utilizing CDP-Star as a substrate, were developed for murine intestinal alkaline phosphatase (mIAP), human intestinal alkaline phosphatase (hIAP), human placental alkaline phosphatase (PLAP), and human tissue-nonspecific alkaline phosphatase (TNAP) isozymes. Using these 1,536-well assays, concurrent HTS screens of the MLSMR library of 323,000 compounds were conducted for human and mouse IAP isozymes monitoring both inhibition and activation. This parallel screening approach led to identification of a novel inhibitory scaffold selective for murine intestinal alkaline phosphatase. SAR efforts based on parallel testing of analogs against different AP isozymes generated a potent inhibitor of the murine IAP with IC50 of 540 nM, at least 65-fold selectivity against human TNAP, and >185 selectivity against human PLAP. PMID:23860652

  5. Alkaline battery, separator therefore

    Science.gov (United States)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

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

    Institute of Scientific and Technical Information of China (English)

    宋文磊; 许成; 王林均; 吴敏; 曾亮; 王丽泽; 冯梦

    2013-01-01

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

  7. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.;

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  8. Earth System Governance: Facing the Challenges of Climate Change

    Directory of Open Access Journals (Sweden)

    Susana Camargo Vieira

    2013-01-01

    Full Text Available YOUNG, Oran R. Institutional Dynamics: Emergent Patterns in International Environmental Governance. Cambridge (Massachusets, USA: The MIT Press, 2010. Earth System Governance Series. 225p. (Paperback; alkaline paper. ISBN 978-0-262-51440-8.

  9. The alkaline and alkaline-carbonatite magmatism from Southern Brazil

    Science.gov (United States)

    Ruberti, E.; Gomes, C. D. B.; Comin-Chiaramonti, P.

    2015-12-01

    Early to Late Cretaceous lasting to Paleocene alkaline magmatism from southern Brazil is found associated with major extensional structural features in and around the Paraná Basin and grouped into various provinces on the basis of several data. Magmatism is variable in size, mode of occurrence and composition. The alkaline rocks are dominantly potassic, a few occurrences showing sodic affinity. The more abundant silicate rocks are evolved undersaturated to saturated in silica syenites, displaying large variation in igneous forms. Less evolved types are restricted to subvolcanic environments and outcrops of effusive suites occur rarely. Cumulatic mafic and ultramafic rock types are very common, particularly in the alkali-carbonatitic complexes. Carbonatite bodies are represented by Ca-carbonatites and Mg-carbonatites and more scarcely by Fe-carbonatites. Available radiometric ages for the alkaline rocks fit on three main chronological groups: around 130 Ma, subcoveal with the Early Cretaceous flood tholeiites of the Paraná Basin, 100-110 Ma and 80-90 Ma (Late Cretaceous). The alkaline magmatism also extends into Paleocene times, as indicated by ages from some volcanic lavas. Geochemically, alkaline potassic and sodic rock types are distinguished by their negative and positive Nb-Ta anomalies, respectively. Negative spikes in Nb-Ta are also a feature common to the associated tholeiitic rocks. Sr-Nd-Pb systematics confirm the contribution of both HIMU and EMI mantle components in the formation of the alkaline rocks. Notably, Early and Late Cretaceous carbonatites have the same isotopic Sr-Nd initial ratios of the associated alkaline rocks. C-O isotopic Sr-Nd isotopic ratios indicate typical mantle signature for some carbonatites and the influence of post-magmatic processes in others. Immiscibility of liquids of phonolitic composition, derived from mafic alkaline parental magmas, has been responsible for the origin of the carbonatites. Close association of alkaline

  10. Destructive Adsorption of Carbon Tetrachloride on Alkaline Earth Metal Oxides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Mestl, Gerhard; Rosynek, Michael P.; Krawietz, Thomas R.; Haw, James F.; Lunsford, Jack H.

    2001-01-01

    The destructive adsorption of CCl4 on MgO, CaO, SrO, and BaO has been studied as a function of the reaction temperature and the amount of CCl4 injected. The reaction was followed using in situ Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and 13 C mag

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

    Science.gov (United States)

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

    2013-01-21

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

  12. The Assessment of Radioactive Body Burdens of the Alkaline Earths

    International Nuclear Information System (INIS)

    The difficulties in obtaining data on the metabolism of bone-seeking radioactive isotopes in man are widely appreciated, especially on the distribution of the isotope between different bones and the microscopic distribution within the same bone. If a full understanding of the metabolism in man is to be obtained, there is at present no alternative but to resort to the use of experimental animals. The calcium and strontium metabolism of the rabbit, which is the smallest animal to have similar skeletal structure to that of human bone, has been studied. The research was planned to include as many parameters as possible. These included specific activity measurements of plasma, urine and faeces, total retention in the skeleton as well as individual bones and in some cases soft tissue. In addition the microscopic distribution of the isotope was studied by quantitative autoradiographic techniques at different time intervals. The results have been considered in the light of various models proposed for the retention of bone-seeking isotopes in mammals and the limitations of each of these models have been assessed. Measurements have been made over sufficiently long time intervals compared with the life-span of the rabbit to enable predictions to be made about the long-term behaviour in man. The results indicate that none of the existing models is completely satisfactory but that a modification of the power function is the most useful. The importance of exchange, as well as resorption, for the removal of radioactive isotopes from the skeleton is well illustrated by the quantitative autoradiographic measurements. (author)

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

    Science.gov (United States)

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

    2014-02-11

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

  14. Ultracold spin-polarized mixtures of 2Sigma molecules with S-state atoms: Collisional stability and implications for sympathetic cooling

    CERN Document Server

    Tscherbul, T V; Buchachenko, A A

    2011-01-01

    The prospects of sympathetic cooling of polar molecules with magnetically co-trapped alkali-metal atoms are generally considered poor due to strongly anisotropic atom-molecule interactions leading to large spin relaxation rates. Using rigorous quantum scattering calculations based on ab initio interaction potentials, we show that inelastic spin relaxation in low-temperature collisions of CaH(2Sigma) molecules with Li and Mg atoms occurs at a slow rate despite the strongly anisotropic interactions. This unexpected result, which we rationalize using multichannel quantum defect theory, opens up the possibility of sympathetic cooling of polar 2Sigma molecules with alkali-metal and alkaline-earth atoms in a magnetic trap.

  15. Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments

    Science.gov (United States)

    Kitadai, Norio

    2015-12-01

    Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

  16. Magnetic field-induced spectroscopy of forbidden optical transitions with application to lattice-based optical atomic clocks.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Oates, C W; Hoyt, C W; Barber, Z W; Hollberg, L

    2006-03-01

    We develop a method of spectroscopy that uses a weak static magnetic field to enable direct optical excitation of forbidden electric-dipole transitions that are otherwise prohibitively weak. The power of this scheme is demonstrated using the important application of optical atomic clocks based on neutral atoms confined to an optical lattice. The simple experimental implementation of this method--a single clock laser combined with a dc magnetic field--relaxes stringent requirements in current lattice-based clocks (e.g., magnetic field shielding and light polarization), and could therefore expedite the realization of the extraordinary performance level predicted for these clocks. We estimate that a clock using alkaline-earth-like atoms such as Yb could achieve a fractional frequency uncertainty of well below 10(-17) for the metrologically preferred even isotopes.

  17. China's rare-earth industry

    Science.gov (United States)

    Tse, Pui-Kwan

    2011-01-01

    Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

  18. Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

    Science.gov (United States)

    Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

    2016-10-01

    Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline hydrothermal vents (Russell et al., 2014). Hydrothermal chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311–318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm

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

    International Nuclear Information System (INIS)

    A 1:100.000 geological map shows the main outcrops, covering about 50 Km2, of the leucocratic alkaline rocks, ultra basic alkaline rocks, carbonatites and volcanic breccias which intruded the Gondwanic sedimentary rocks within a short time interval and characterize the Alkaline District of Lages. Chemical analyses of 33 whole-rock samples confirm the petrographic classification, but the agpaitic indexes, mostly below 1.0, do not reflect the mineralogical variations of the leucocratic alkaline rocks adequately. Partial REE analyses indicate that the light as well as the heavy rare earth contents decrease from the basic to the more evolved rocks, the La/Y ratio remaining approximately constant. Eleven new K/Ar ages from porphyritic nepheline syenites porphyritic phonolites, ultra basic alkaline rocks and pipe-breccias, together with six already available ages, show a major concentration in the range 65 to 75 Ma, with a mode at ca. 70 Ma. But one Rb/Sr whole-rock reference isochron diagram gives an age of 82+-6 Ma for the agpaitic phonolites of the Serra Chapada, which are considered younger than the miaskitic porphyriric nepheline syenites. The 87 Sr/86 Sr ratios of 0.705-0.706 are compatible with a sub continental mantelic origin, devoid of crustal contamination. A petrogenetic model based on subtraction diagrams and taking into consideration the geologic, petrographic, mineralogic and petrochemical characteristics of the alkaline rocks of Lages consists of limited partial melting with CO2, contribution of the previously metasomatized upper mantle, in a region submitted to decompression. (author)

  20. Alkali-metal/alkaline-earth-metal fluorine beryllium borate NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} with large nonlinear optical properties in the deep-ultraviolet region

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A. H., E-mail: maalidph@yahoo.com [New Technologies—Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Huang, Hongwei [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Kamarudin, H. [Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Auluck, S. [Council of Scientific and Industrial Research—National Physical Laboratory, Dr. K S Krishnan Marg, New Delhi 110012, India and Physics Department, Indian Institute of Technology - Delhi, Hauz Khas, New Delhi 110016 (India)

    2015-02-28

    The linear optical response and second harmonic generation (SHG) in alkali-metal/alkaline-earth-metal fluorine beryllium borate NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} are investigated by means of density functional theory. Calculations are performed using four types of exchange correlations: Ceperley-Alder local density approximation, Perdew Burke and Ernzerhof general gradient approximation, Engel-Vosko generalized gradient approximation, and the recently modified Becke-Johnson potential (mBJ). The mBJ approach brings the calculated band gap (7.20 eV) in excellent agreement with the experimental one (7.28 eV). The calculated values of the uniaxial anisotropy δε=−0.076 and the birefringence Δn(0)=0.052 indicate considerable anisotropy in the linear optical properties, which makes it favorable for the second harmonic generation. The dominant component of the second harmonic generation is χ{sub 111}{sup (2)}(ω). The value of |χ{sub 111}{sup (2)}(ω)| is about 1.2 pm/V at λ = 1064 nm in agreement with previous calculations. To analyze the origin of the high SHG of NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} single crystals, we have correlated the features of |χ{sub 111}{sup (2)}(ω)| spectra with the features of ε{sub 2}(ω) spectra as a function of ω/2 and ω. From the calculated dominant component |χ{sub 111}{sup (2)}(ω)|, we find that the microscopic first hyperpolarizability, β{sub 111}, the vector components along the dipole moment direction is 0.5 × 10{sup −30} esu at static limit and 0.6 × 10{sup −30} esu at λ = 1064 nm.

  1. Non-equilibrium 8π Josephson effect in atomic Kitaev wires

    Science.gov (United States)

    Laflamme, C.; Budich, J. C.; Zoller, P.; Dalmonte, M.

    2016-08-01

    The identification of fractionalized excitations, such as Majorana quasi-particles, would be a striking signal of the realization of exotic quantum states of matter. While the paramount demonstration of such excitations would be a probe of their non-Abelian statistics via controlled braiding operations, alternative proposals exist that may be easier to access experimentally. Here we identify a signature of Majorana quasi-particles, qualitatively different from the behaviour of a conventional superconductor, which can be detected in cold atom systems using alkaline-earth-like atoms. The system studied is a Kitaev wire interrupted by an extra site, which gives rise to super-exchange coupling between two Majorana-bound states. We show that this system hosts a tunable, non-equilibrium Josephson effect with a characteristic 8π periodicity of the Josephson current. The visibility of the 8π periodicity of the Josephson current is then studied including the effects of dephasing and particle losses.

  2. Matrix reactions of copper atoms and ozone molecules. Infrared spectrum of CuO

    Science.gov (United States)

    Tevault, D. E.; Mowery, R. L.; De Marco, R. A.; Smardzewski, R. R.

    1981-04-01

    The matrix reactions of copper atoms with ozone have been studied by infrared spectroscopy. Two products were found in the initial deposit: CuO3, which has a strong absorption at 802.3 cm-1, and CuO, which has its main feature, corresponding to the 63Cu16O isotopic species, at 628.0 cm-1 in solid argon. Copper atom reactions with oxygen-18-enriched ozone samples were used to obtain species identifications. The CuO3 absorption was very similar in frequency and isotopic splitting behavior to alkali and alkaline earth metal ozonide species previously studied in matrices. The CuO frequency is in good agreement with gas phase measurements which put the ground state CuO vibrational fundamental at 631.3 cm-1. Temperature cycling of the Cu-O3 matrices leads to CuO4 formation by the secondary reaction of CuO with unreacted ozone.

  3. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  4. When can ocean acidification impacts be detected from decadal alkalinity measurements?

    Science.gov (United States)

    Carter, B. R.; Frölicher, T. L.; Dunne, J. P.; Rodgers, K. B.; Slater, R. D.; Sarmiento, J. L.

    2016-04-01

    We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty.

  5. Biological Apatite Formed from Polyphosphate and Alkaline Phosphatase May Exchange Oxygen Isotopes from Water through Carbonate

    Science.gov (United States)

    Omelon, S. J.; Stanley, S. Y.; Gorelikov, I.; Matsuura, N.

    2011-12-01

    The oxygen isotopic composition in bone mineral phosphate is known to reflect the local water composition, environmental humidity, and diet1. Once ingested, biochemical processes presumably equilibrate PO43- with "body water" by the many biochemical reactions involving PO43- 2. Blake et al. demonstrated that enzymatic release of PO43- from organophosphorus compounds, and microbial metabolism of dissolved orthophosphate, significantly exchange the oxygen in precipitated apatite within environmental water3,4, which otherwise does not exchange with water at low temperatures. One of the enzymes that can cleave phosphates from organic substrates is alkaline phosphastase5, the enzyme also associated with bone mineralization. The literature often states that the mineral in bone in hydroxylapatite, however the mineral in bone is carbonated apatite that also contains some fluoride6. Deprotonation of HPO32- occurs at pH 12, which is impossibly high for biological system, and the predominate carbonate species in solution at neutral pH is HCO3-. To produce an apatite mineral without a significant hydroxyl content, it is possible that apatite biomineralization occurs through a polyphosphate pathway, where the oxygen atom required to transform polyphosphate into individual phosphate ions is from carbonate: [PO3-]n + CO32- -> [PO3-]n-1 + PO43- + CO2. Alkaline phosphatase can depolymerise polyphosphate into orthophosphate5. If alkaline phosphatase cleaves an oxygen atom from a calcium-carbonate complex, then there is no requirement for removing a hydrogen atom from the HCO3- or HPO43- ions of body water to form bioapatite. A mix of 1 mL of 1 M calcium polyphosphate hydogel, or nano-particles of calcium polyphosphate, and amorphous calcium carbonate were reacted with alkaline phosphatase, and maintained at neutral to basic pH. After two weeks, carbonated apatite and other calcium phosphate minerals were identified by powder x-ray diffraction. Orthophosphate and unreacted

  6. Nucleotide sequences encoding a thermostable alkaline protease

    Science.gov (United States)

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  7. Earth\\'s Mass Variability

    OpenAIRE

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mecha...

  8. Discover Earth

    Science.gov (United States)

    Steele, Colleen

    1998-01-01

    Discover Earth is a NASA-sponsored project for teachers of grades 5-12, designed to: (1) enhance understanding of the Earth as an integrated system; (2) enhance the interdisciplinary approach to science instruction; and (3) provide classroom materials that focus on those goals. Discover Earth is conducted by the Institute for Global Environmental Strategies in collaboration with Dr. Eric Barron, Director, Earth System Science Center, The Pennsylvania State University; and Dr. Robert Hudson, Chair, the Department of Meteorology, University of Maryland at College Park. The enclosed materials: (1) represent only part of the Discover Earth materials; (2) were developed by classroom teachers who are participating in the Discover Earth project; (3) utilize an investigative approach and on-line data; and (4) can be effectively adjusted to classrooms with greater/without technology access. The Discover Earth classroom materials focus on the Earth system and key issues of global climate change including topics such as the greenhouse effect, clouds and Earth's radiation balance, surface hydrology and land cover, and volcanoes and climate change. All the materials developed to date are available on line at (http://www.strategies.org) You are encouraged to submit comments and recommendations about these materials to the Discover Earth project manager, contact information is listed below. You are welcome to duplicate all these materials.

  9. On the apparent CO2 absorption by alkaline soils

    Directory of Open Access Journals (Sweden)

    X. Chen

    2014-02-01

    Full Text Available Alkaline soils in the Gubantonggut Desert were recently demonstrated socking away large quantities of CO2 in an abiotic form. This demands a better understanding of abiotic CO2 exchange in alkaline sites. Reaction of CO2 with the moisture or dew in the soil was conjectured as a potential mechanism. The main goal of this study is to determine the extent to which the dew deposition modulates Land–Atmosphere CO2 exchange at highly alkaline sites (pH ~ 10. Experiments were conducted at the most barren sites (canopy coverage 2 fluxes were measured using a micro-lysimeters and an automated flux system (LI-COR, Lincoln, Nebraska, USA, respectively. There is an evident increase of dew deposition in nocturnal colder temperatures and decrease in diurnal warmer temperatures. Variations of soil CO2 flux are almost contrary, but the increase in diurnal warmer temperatures is obscure. It was shown that the accumulation and evaporation of dew in the soil motivates the apparent absorption and release of CO2. It was demonstrated that dew amounts in the soil has an exponential relation with the part in Fc beyond explanations of the worldwide utilized Q10 model. Therefore dew deposition in highly alkaline soils exerted a potential CO2 sink and can partly explain the apparent CO2 absorption. This implied a crucial component in the net ecosystem carbon balance (NECB at alkaline sites which occupies approximately 5% of the Earth's land surface (7 million km. Further explorations for its mechanisms and representativeness over other arid climate systems have comprehensive perspectives in the quaternary research.

  10. Development of alkaline fuel cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari [Colorado School of Mines, Golden, CO; Horan, James L. [Colorado School of Mines, Golden, CO; Caire, Benjamin R. [Colorado School of Mines, Golden, CO; Ziegler, Zachary C. [Colorado School of Mines, Golden, CO; Herring, Andrew M. [Colorado School of Mines, Golden, CO; Yang, Yuan [Colorado School of Mines, Golden, CO; Zuo, Xiaobing [Argonne National Laboratory, Argonne, IL; Robson, Michael H. [University of New Mexico, Albuquerque, NM; Artyushkova, Kateryna [University of New Mexico, Albuquerque, NM; Patterson, Wendy [University of New Mexico, Albuquerque, NM; Atanassov, Plamen Borissov [University of New Mexico, Albuquerque, NM

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassov's research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herring's group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  11. Development of alkaline fuel cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  12. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  13. Ce3+/Tb3+ Doped Alkaline-Earth Borate Glasses Employed in Enhanced Solar Cells%增强型太阳能电池用Ce3+/Tb3+掺杂碱土硼酸盐玻璃

    Institute of Scientific and Technical Information of China (English)

    杨朋; 赵昕; 王志强; 林海

    2015-01-01

    Ce3+ and Tb3+ doped alkaline earth borate (LKZBSB) glasses and the photoluminescence properties of glass system have been fabricated and investigated ,and the observed violet and green fluorescences are originated from Ce3+ and Tb3+ emit-ting centers ,respectively .Four emission bands peaked at 487 ,543 ,586 and 621 nm are attributed to the emission transitions 5 D4 → 7 F6 ,5 D4 → 7 F5 ,5 D4 → 7 F4 and 5 D4 → 7 F3 of Tb3+ ,respectively ,and consists of a broad emission band peaking at 389 nm attributed to 5 d→4 f electric dipole allowed transition of Ce3+ .With the introduction of Ce3+ ,the effective excitation wavelength range of Tb3+ in LKZBSB glasses are remarkably expanded ,and the enhanced factor of green fluorescence of Tb3+ in Ce3+ /Tb3+co-doped LKZBSB glasses is up to 73 times in medium-wavelength ultraviolet (UVB) excitation region ,compared with that in Tb3+ single-doped case .The results show that the conversion from ultraviolet (UV) radiation to visible light is efficient in Ce3+ /Tb3+ doped LKZBSB glasses ,demonstrating that the glasses have potential values in developing enhanced solar cell as a conver-sion layer .%制备并研究了Ce3+和Tb3+掺杂碱土硼酸盐(LKZBSB)玻璃及该体系玻璃的光致发光特性,观察到起源于Ce3+和T b3+发光中心的蓝紫色和绿色荧光。波长为487,543,586和621 nm的发射峰分别归属于Tb3+的5D4→7F6,5D4→7F5,5D4→7F4和5D4→7F3发射跃迁,389nm的宽带发射峰归属于Ce3+的5d→4f电偶级允许跃迁。通过Ce3+引入,LKZBSB玻璃中Tb3+可见光发射的有效激发波长范围显著扩大,尤其在中波紫外激发下,Ce3+/T b3+共掺样品中T b3+的绿光发射强度相对于T b3+单掺样品,增强系数高达73倍。结果表明,在Ce3+/Tb3+掺杂LKZBSB玻璃中,紫外辐射可有效转换成可见光,作为光转换层对增强型太阳能电池的研发具有重要的应用价值。

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

    Science.gov (United States)

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

    2016-03-01

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

  15. Relativistic equation-of-motion coupled-cluster method for the double ionization potentials of the closed-shell atoms

    CERN Document Server

    Pathak, Himadri; Sahoo, B K; Das, B P; Vaval, Nayana; Pal, Sourav

    2014-01-01

    We report the implementation of the relativistic equation-of-motion coupled-cluster method to calculate double ionization spectra (DI-EOMCC) of the closed-shell atomic systems. This method is employed to calculate principal valence double ionization potential values of He and alkaline earth metal (Be, Mg, Ca, Sr and Ba) atoms. Our results are compared with the results available from the national institute of science and technology (NIST) database and other ab initio calculations. We have achieved an accuracy of ~ 0.1%, which is an improvement over the first principles T-matrix calculations [J. Chem. Phys. 123, 144112 (2005)]. We also present results using the second-order many-body perturbation theory and the random -phase approximation in the equation-of-motion framework and these results are compared with the DI-EOMCC results.

  16. Alkaline fuel cell performance investigation

    Science.gov (United States)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  17. Atom Chips

    CERN Document Server

    Folman, R; Cassettari, D; Hessmo, B; Maier, T; Schmiedmayer, J; Folman, Ron; Krüger, Peter; Cassettari, Donatella; Hessmo, Björn; Maier, Thomas

    1999-01-01

    Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

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

    Indian Academy of Sciences (India)

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

    2013-06-01

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

  19. Alkaline Water and Longevity: A Murine Study.

    Science.gov (United States)

    Magro, Massimiliano; Corain, Livio; Ferro, Silvia; Baratella, Davide; Bonaiuto, Emanuela; Terzo, Milo; Corraducci, Vittorino; Salmaso, Luigi; Vianello, Fabio

    2016-01-01

    The biological effect of alkaline water consumption is object of controversy. The present paper presents a 3-year survival study on a population of 150 mice, and the data were analyzed with accelerated failure time (AFT) model. Starting from the second year of life, nonparametric survival plots suggest that mice watered with alkaline water showed a better survival than control mice. Interestingly, statistical analysis revealed that alkaline water provides higher longevity in terms of "deceleration aging factor" as it increases the survival functions when compared with control group; namely, animals belonging to the population treated with alkaline water resulted in a longer lifespan. Histological examination of mice kidneys, intestine, heart, liver, and brain revealed that no significant differences emerged among the three groups indicating that no specific pathology resulted correlated with the consumption of alkaline water. These results provide an informative and quantitative summary of survival data as a function of watering with alkaline water of long-lived mouse models.

  20. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  1. Grace DAKASEP alkaline battery separator

    Science.gov (United States)

    Giovannoni, R. T.; Lundquist, J. T.; Choi, W. M.

    1987-01-01

    The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.

  2. Mechanism of gold dissolving in alkaline thiourea solution

    Institute of Scientific and Technical Information of China (English)

    CHAI Li-yuan; WANG Yun-yan

    2007-01-01

    Reaction mechanism of gold dissolving in alkaline thiourea solution was studied by electrochemical methods, such as cyclic voltammetry, chronopotentiometry, AC impedance, linear sweep voltammetry. Apparent activation energy of anodic process of gold electrode dissolving in alkaline thiourea solution is 14.91 kJ/mol. Rate determining step is the process of gold thiourea complex diffusing away from electrode surface to solution. The results of AC impedance and chronopotentiometry indicate that thiourea adsorbs on gold electrode surface before dissolving in solution. There does not exist proceeding chemical reactions. Formamidine disulfide, the decomposed product of thiourea, does not participate the process of gold dissolution and thiourea complex. Species with electro-activity produced in the process of electrode reaction adsorbs on the electrode surface. In alkaline thiourea solution, gold dissolving mechanism undergoes the following courses: adsorption of thiourea on electrode surface; charge transfer from gold atom to thiourea molecule; Au[SC(NH2)2]ads+ receiving a thiourea molecule and forming stable Au[SC(NH2)2]2+; and then Au[SC(NH2)2]2+diffusing away from the electrode surface to solution, the last step is the rate-determining one.

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

    International Nuclear Information System (INIS)

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

  4. NASA Benefits Earth

    Science.gov (United States)

    Robinson, Julie A.

    2009-01-01

    This slide presentation reviews several ways in which NASA research has benefited Earth and made life on Earth better. These innovations include: solar panels, recycled pavement, thermometer pill, invisible braces for straightening teeth, LASIK, aerodynamic helmets and tires for bicycles, cataract detection, technology that was used to remove Anthrax spores from mail handling facilities, study of atomic oxygen erosion of materials has informed the restoration of artwork, macroencapsulation (a potential mechanism to deliver anti cancer drugs to specific sites), and research on a salmonella vaccine. With research on the International Space Station just beginning, there will be opportunities for entrepreneurs and other government agencies to access space for their research and development. As well as NASA continuing its own research on human health and technology development.

  5. Determination of molybdenum in flotation concentrates by atomic absorption spectrophotometry

    International Nuclear Information System (INIS)

    Molybdenum was determined by atomic absorption spectrophotometry in 0.05 N ammoniacal solution after the decomposition of the concentrate with aqua regia. Negros ore from Philippines was used as a flotation feed, which contained chalcopyrites and calcium-magnesium minerals. Among the metals tested copper, iron and the alkaline earths interfered. Less than 50 ppm of copper yielded lower results for molybdenum. Higher results came out with more than 50 ppm of copper. In the presence of iron and citric acid (0.4 g/100 ml) which is a suppressor for hydroxide formation, a lower estimation resulted for molybdenum. Calcium interfered, lower results by 2 and >10% being obtained with respective 2.5 and 20 ppm of calcium. More than 20 ppm of magnesium behaved similarly. Sodium sulfate (0.5 g/100 ml) served as the suppressor for copper, iron and citric acid; 100 ppm each of copper and iron did not interfere in this way. Interferences due to calcium and magnesium (less than 60 ppm) was able to be masked by the addition of sodium silicate (200 ppm as silica). The analysis of flotation products and synthetic samples consisting of molybdenite, chalcopyrite, calcium chloride and magnesium sulfate revealed that the atomic absorption method can be applied to the analysis of the concentrates for molybdenum with an error of about 2%. (auth.)

  6. Alkaline azide mutagenicity in cowpea

    International Nuclear Information System (INIS)

    Sodium azide is known as a potent mutagen in cereals and legumes. It is very effective in acidic medium in barley. Here an attempt is made to measure the effectiveness of sodium azide in alkaline medium (pH 7.4) on cowpea (Vigna unguiculata (L.) Walp., variety FS-68). Seeds pre-soaked in distilled water for 5 hours were treated with different concentrations (10-6, 10-5, 10-4 and 10-3M) of sodium azide (NaN3) for 4 hours at 28± 2 deg. C. Bottles were intermittently shaken, then the seeds were thoroughly washed in running tap water and subsequently planted in pots. The treatment caused significant biological damage such as reduction in seed germination, length of root and shoot, number of nodules and pods per plant and morphological leaf variations. Morphological, as well as chlorophyll mutants, were detected in M2

  7. Atom chips

    CERN Document Server

    Reichel, Jakob

    2010-01-01

    This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.

  8. Rydberg atom in gravity

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Aniket [Indian Institute of Technology Delhi, New Delhi (India)

    2012-07-01

    Recently, Chiao predicted the quantum incompressibility of a falling Rydberg atom. A Hydrogen-like atom was considered in a very high n,l=m=n-1 state to calculate the effects of tidal gravitational forces on these states. The high values of quantum numbers ensure that gravitational effect is measurable on the *stretch* state. We consider a similar atom and derive the energy of a particular level under the influence of Newtonian gravity. A change in the frequency of observed transition is predicted for a freely falling Hydrogen atom. This change is calculated both in Newtonian gravity and in curved space. We see that the change in energy of the electron under gravity also depends on its principal quantum number. Thus there will be a shift in the frequency of the photon emitted by an electron making an ordinary transition from the state n=100, l=99, m=99 to the state n=99, l=98, m=98. Though this shift is quite less to be observed on Earth, it is measurable in satellites in a highly elliptical orbit about the earth, by spectroscopic methods. A similar result was derived by Chiao recently using a different argument. We conclude that the effect described by Chiao will be masked to a very large extent by the effect calculated above. Such perturbations might be important in emission spectra of white dwarfs and neutron stars.

  9. Formation of molecular ions by radiative association of cold trapped atoms and ions

    Science.gov (United States)

    Dulieu, Olivier; da Silva, Humberto, Jr.; Aymar, Mireille; Raoult, Maurice

    2015-05-01

    Radiative emission during cold collisions between trapped laser-cooled Rb atoms and alkaline-earth ions (Ca+ , Sr+ , Ba+) and Yb+ are studied theoretically, using accurate effective-core-potential based quantum chemistry calculations of potential energy curves and transition dipole moments of the related molecular ions. Radiative association of molecular ions is predicted to occur for all systems with a cross section two to ten times larger than the radiative charge transfer one. Partial and total rate constants are also calculated and compared to available experiments. Narrow shape resonances are expected, which could be detectable at low temperature with an experimental resolution at the limit of the present standards. Vibrational distributions show that the final molecular ions are not created in their ground state level. Supported by the Marie-Curie ITN ``COMIQ: Cold Molecular Ions at the Quantum limit'' of the EU (#607491).

  10. Formation of molecular ions by radiative association of cold trapped atoms and ions

    CERN Document Server

    Silva, Humberto Da; Aymar, Mireille; Dulieu, Olivier

    2015-01-01

    Radiative emission during cold collisions between trapped laser-cooled Rb atoms and alkaline-earth ions (Ca + , Sr + , Ba +) and Yb + are studied theoretically, using accurate effective-core-potential based quantum chemistry calculations of potential energy curves and transition dipole moments of the related molecular ions. Radiative association of molecular ions is predicted to occur for all systems with a cross section two to ten times larger than the radiative charge transfer one. Partial and total rate constants are also calculated and compared to available experiments. Narrow shape resonances are expected, which could be detectable at low temperature with an experimental resolution at the limit of the present standards. Vibrational distributions are also calculated, showing that the final molecular ions are not created in their ground state level.

  11. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  12. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  13. The importance of being alkaline

    OpenAIRE

    M. J. Russell

    2003-01-01

    The earliest forms of "protolife" on Earth must have been able to reproduce and replicate; it is likely that they were also cellular. How might such systems have formed? In his Perspective, Russell highlights the report by Hanczyc et al., who show that clay particles can catalyze the formation of lipid vesicles. These particles also adsorb RNA. If the vesicles are forced to divide, RNA is distributed among the daughter vesicles. Similar conditions to those used in the experiments may have exi...

  14. Atom interferometry

    International Nuclear Information System (INIS)

    We will first present a development of the fundamental principles of atom interferometers. Next we will discuss a few of the various methods now available to split and recombine atomic De Broglie waves, with special emphasis on atom interferometers based on optical pulses. We will also be particularly concerned with high precision interferometers with long measurement times such those made with atomic fountains. The application of atom interferometry to the measurement of the acceleration due to gravity will be detailed. We will also develop the atom interferometry based on adiabatic transfer and we will apply it to the measurement of the photon recoil in the case of the Doppler shift of an atomic resonance caused by the momentum recoil from an absorbed photon. Finally the outlook of future developments will be given. (A.C.)

  15. Inorganic-organic separators for alkaline batteries

    Science.gov (United States)

    Sheibley, D. W. (Inventor)

    1978-01-01

    A flexible separator is reported for use between the electrodes of Ni-Cd and Ni-Zn batteries using alkaline electrolytes. The separator was made by coating a porous substrate with a battery separator composition. The coating material included a rubber-based resin copolymer, a plasticizer and inorganic and organic fillers which comprised 55% by volume or less of the coating as finally dried. One or more of the filler materials, whether organic or inorganic, is preferably active with the alkaline electrolyte to produce pores in the separator coating. The plasticizer was an organic material which is hydrolyzed by the alkaline electrolyte to improve conductivity of the separator coating.

  16. Release of fission products from oxidised zircaloy cladding in contact with an alkaline solution

    International Nuclear Information System (INIS)

    Before nuclear spent fuel reprocessing, the cladding tubes are sectioned into pieces called hulls in order to release the UO2 pellets. The hulls are collected as solid wastes and were embedded inside a concrete structure until 1995. In the perspective of geological storage, a great interest is given to iodine release during contact between hulls and basic water infiltrated inside the concrete structure. Experiments were performed on zircaloy or zirconium oxidised samples representative of oxidised hulls surfaces. Corrosion tests were performed in autoclave. The specimens were exposed to a basic solution at 250 deg C, 275 deg C and 300 deg C. The corrosion tests were conducted during 12 weeks with regular sampling every two weeks. The partial dissolution of the oxide coating was studied using the rare earth europium element as a surface marker of zirconia. Such a choice is based on experimental results ensuring that this marker will not diffuse in the 250-300 deg C temperature range. Europium was introduced by ion implantation (Rp = 42 nm). The evolutions of europium concentration profiles measured at each corrosion step show that a non homogeneous dissolution of zirconia occurs in this alkaline medium. The mean dissolution rate is equal to 1 nm/day at 300 deg C. In order to analyse the mechanism involved in iodine migration, iodine atoms were introduced in samples by ion implantation. The iodine profile evolution allows to identify two steps in iodine release. A rapid desorption which could not be related to zirconia dissolution and then a stabilisation as far as low the iodine concentration (0.3 at.%) were reached. We demonstrated that hydrogen (representative of hydroxyl) migration in zirconia is clearly enhanced by the presence of iodine in the sample and that the iodine release is correlated to that of hydroxyl ions. The correlation of the behaviour between iodine and hydroxyl ions could be explained by the creation of complexes. (author)

  17. Column system using diaion HP-2MG for determination of some metal ions by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tuzen, Mustafa; Soylak, Mustafa

    2004-02-23

    A column solid-phase extraction method for the preconcentration and determination of cadmium(II), copper(II), cobalt(II), iron(III), lead(II), nickel(II) and zinc(II) dithizone chelates by atomic absorption spectrometry has been described. Diaion HP-2MG was used as adsorbent for column studies. The influences of the various analytical parameters including pH of the aqueous solutions, amounts of ligand and resin were investigated for the retentions of the analyte ions. The recovery values are ranged from 95 to 102%. The influences of alkaline and earth alkaline ions were also discussed. The preconcentration factor was 375, when the sample volume and final volume are 750 and 2 ml, respectively. The detection limits of the analyte ions (k=3, N=21) were varying 0.08 {mu}g/l for cadmium to 0.25 {mu}g/l for lead. The relative standard deviations of the determinations at the concentration range of 1.8x10{sup -4} to 4.5x10{sup -5} mmol for the investigated elements were found to be lower than 9%. The proposed solid-phase extraction procedure were applied to the flame atomic absorption spectrometric determinations of analyte ions in natural waters (sea, tap, river), microwave digested samples (milk, red wine and rice) and two different reference standard materials (SRM1515 apple leaves and NRCC-SLRS-4 riverine water)

  18. Atomic physics

    International Nuclear Information System (INIS)

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 23Po,2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 23Po level of helium-like krypton

  19. Real-time materials evolution visualized within intact cycling alkaline batteries

    Energy Technology Data Exchange (ETDEWEB)

    Gallaway, JW; Erdonmez, CK; Zhong, Z; Croft, M; Sviridov, LA; Sholklapper, TZ; Turney, DE; Banerjee, S; Steingart, DA

    2014-01-01

    The scientific community has focused on the problem of inexpensive, safe, and sustainable large-scale electrical energy storage, which is needed for a number of emerging societal reasons such as stabilizing intermittent renewables-based generation like solar and wind power. The materials used for large-scale storage will need to be low cost, earth-abundant, and safe at the desired scale. The Zn-MnO2 "alkaline" battery chemistry is associated with one-time use, despite being rechargeable. This is due to material irreversibilities that can be triggered in either the anode or cathode. However, as Zn and MnO2 have high energy density and low cost, they are economically attractive even at limited depth of discharge. As received, a standard bobbin-type alkaline cell costs roughly $20 per kW h. The U. S. Department of Energy ARPA-E $100 per kW h cost target for grid storage is thus close to the cost of alkaline consumer primary cells if re-engineered and/or cycled at 5-20% nominal capacity. Herein we use a deeply-penetrating in situ technique to observe ZnO precipitation near the separator in an alkaline cell anode cycled at 5% DOD, which is consistent with cell failures observed at high cycle life. Alkaline cells designed to avoid such causes of cell failure could serve as a low-cost baseload for large-scale storage.

  20. Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents

    Science.gov (United States)

    Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

    2016-09-01

    Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H2 and CO2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

  1. Technetium recovery from high alkaline solution

    Science.gov (United States)

    Nash, Charles A.

    2016-07-12

    Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

  2. Alkaline tolerant dextranase from streptomyces anulatus

    Science.gov (United States)

    Decker, Stephen R.; Adney, William S.; Vinzant, Todd B.; Himmel, Michael E.

    2003-01-01

    A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

  3. Alkaline regenerative fuel cell systems for energy storage

    Science.gov (United States)

    Schubert, F. H.; Reid, M. A.; Martin, R. E.

    1981-01-01

    A description is presented of the results of a preliminary design study of a regenerative fuel cell energy storage system for application to future low-earth orbit space missions. The high energy density storage system is based on state-of-the-art alkaline electrolyte cell technology and incorporates dedicated fuel cell and electrolysis cell modules. In addition to providing energy storage, the system can provide hydrogen and oxygen for attitude control of the satellite and for life support. During the daylight portion of the orbit the electrolysis module uses power provided by the solar array to generate H2 and O2 from the product water produced by the fuel cell module. The fuel cell module supplies electrical power during the dark period of the orbit.

  4. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  5. Rare earths

    International Nuclear Information System (INIS)

    General mineralogical-geochemical and analytical characteristics of (lanthanides and yttrium) are presented. It is pointed out that individual RE in complex chemical composition samples are successfully determined by physical methods of the analysis (emission spectral method, spark mass spectrometry method, neutron + activation analysis). RE sum determination is performed by spectrophotometric titrimetric or gravimetric methods. Principal methods of RE separation and concentration, methods of analytical samples dissolution are considered. Detailed descriptions of some specific techniques of determining rare earths in rocks, ores and minerals are presented

  6. Atomic Quantum Simulations of Abelian and non-Abelian Gauge Theories

    CERN Document Server

    CERN. Geneva

    2014-01-01

    Using a Fermi-Bose mixture of ultra-cold atoms in an optical lattice, in a collaboration of atomic and particle physicists, we have constructed a quantum simulator for a U(1) gauge theory coupled to fermionic matter. The construction is based on quantum link models which realize continuous gauge symmetry with discrete quantum variables. At low energies, quantum link models with staggered fermions emerge from a Hubbard-type model which can be quantum simulated. This allows investigations of string breaking as well as the real-time evolution after a quench in gauge theories, which are inaccessible to classical simulation methods. Similarly, using ultracold alkaline-earth atoms in optical lattices, we have constructed a quantum simulator for U(N) and SU(N) lattice gauge theories with fermionic matter based on quantum link models. These systems share qualitative features with QCD, including chiral symmetry breaking and restoration at non-zero temperature or baryon density. Unlike classical simulations, a quantum ...

  7. Prospects for ultracold polar and magnetic chromium-closed-shell-atom molecules

    CERN Document Server

    Tomza, Michał

    2013-01-01

    The properties of the electronic ground state of the polar and paramagnetic chromium--closed-shell-atom molecules have been investigated. State-of-the-art \\textit{ab initio} techniques have been applied to compute the potential energy curves for the chromium--alkaline-earth-metal-atom, CrX (X = Be, Mg, Ca, Sr, Ba), and chromium--ytterbium, CrYb, molecules in the Born-Oppenheimer approximation for the $X^7\\Sigma^+$ high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within Douglas-Kroll-Hess Hamiltonian or energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large interatomic distances, $C_6$, are also reported. Molecules under investigation are an example of species p...

  8. Metastable zinc–nickel alloys deposited from an alkaline electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Magagnin, Luca; Nobili, Luca, E-mail: luca.nobili@polimi.it; Cavallotti, Pietro Luigi

    2014-12-05

    Highlights: • Zn–Ni coatings with high corrosion resistance were prepared by electrodeposition. • The electrodeposited γ alloy is found to be different from the equilibrium γ phase. • A random atomic distribution is proposed for the electrodeposited alloy. • The calculated free energy function can explain the phase composition of Zn–Ni coatings. - Abstract: Zinc alloy offers superior sacrificial protection to steel as the alloy dissolves more slowly than pure zinc. The degree of protection and the rate of dissolution depend on the alloying metal and its composition. In this work, the physico-chemical characterization of zinc–nickel electrodeposits obtained from an alkaline bath is carried out and a description of the structural and thermodynamic properties of these alloys is proposed. Contrary to the common acceptance, XRD spectra and DSC thermal analysis show that the electrodeposited γ alloy has to be regarded as a metastable phase, whose atomic arrangement is different from that of the equilibrium γ intermetallic compound. A model for atomic distribution in the electrodeposited alloy is proposed. The Gibbs free-energy function for the electrodeposited phase has been evaluated and the metastable boundaries of the single-phase and two-phase fields have been calculated. Reasonable agreement is found with experimental values reported in the literature for Zn–Ni coatings with different composition.

  9. Improved electrodes and gas impurity investigations on alkaline electrolysers

    DEFF Research Database (Denmark)

    Reissner, R.; Schiller, G.; Knoeri, T.;

    Alkaline water electrolysis for hydrogenproduction is a well-established techniquebut some technological issues regarding thecoupling of alkaline water electrolysis andRenewable Energy Sources (RES) remain tobe improved.......Alkaline water electrolysis for hydrogenproduction is a well-established techniquebut some technological issues regarding thecoupling of alkaline water electrolysis andRenewable Energy Sources (RES) remain tobe improved....

  10. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  11. Hubbard model for ultracold bosonic atoms interacting via zero-point-energy-induced three-body interactions

    Science.gov (United States)

    Paul, Saurabh; Johnson, P. R.; Tiesinga, Eite

    2016-04-01

    We show that, for ultracold neutral bosonic atoms held in a three-dimensional periodic potential or optical lattice, a Hubbard model with dominant, attractive three-body interactions can be generated. In fact, we derive that the effect of pairwise interactions can be made small or zero starting from the realization that collisions occur at the zero-point energy of an optical lattice site and the strength of the interactions is energy dependent from effective-range contributions. We determine the strength of the two- and three-body interactions for scattering from van der Waals potentials and near Fano-Feshbach resonances. For van der Waals potentials, which for example describe scattering of alkaline-earth atoms, we find that the pairwise interaction can only be turned off for species with a small negative scattering length, leaving the 88Sr isotope a possible candidate. Interestingly, for collisional magnetic Feshbach resonances this restriction does not apply and there often exist magnetic fields where the two-body interaction is small. We illustrate this result for several known narrow resonances between alkali-metal atoms as well as chromium atoms. Finally, we compare the size of the three-body interaction with hopping rates and describe limits due to three-body recombination.

  12. Synchrotron radiation - Applications in the earth sciences

    Science.gov (United States)

    Bassett, W. A.; Brown, G. E., Jr.

    Synchrotron-radiation sources and their characteristics are overviewed along with recent synchrotron-based research on earth materials and future earth-science applications utilizing the next generation of synchrotron-radiation sources presently under construction. Focus is placed on X-ray scattering studies of earth materials (crystalline and noncrystalline) under ambient conditions, diffraction studies of earth materials at high pressures and/or temperatures, spectroscopic studies, primarily X-ray absorption spectroscopy, and spatially resolved X-ray fluorescence studies of compositional variations in earth materials. It is noted that other synchrotron-based methods, such as X-ray tomography and topography may become important in characterizing earth materials, while soft X-ray/vacuum ultraviolet radiation from synchrotron sources can be applied to problems involving the structural environments of low-atomic-number elements and the characterization of surface reactions of minerals with liquids and gases.

  13. Spectrometry of the Earth using neutrino oscillations

    Science.gov (United States)

    Taketa, Akimichi; Rott, Carsten

    2016-04-01

    Neutrinos have favorable properties for measuring the elemental composition deep inside the earth's interior. First, they propagate a long distance almost undisturbed through the earth due to their weak interactions with matter. Secondly, neutrino oscillations in matter are sensitive to the electron density of the medium traversed by them. Therefore, neutrinos can be used for a probe to determine the average atomic mass ratio Z/A of the earth's core by comparing with the earth's nucleus density distribution that is inferred from seismic observations. There is a little uncertainty in densities of the earth's core, but our knowledge of its main light element is still not fixed. With the advent of the new-generation megaton neutrino detectors, neutrino oscillation mass spectrometry will allow us to constrain directly the light elements in the earth's outer core. We report the detail of this novel technic and the sensitivity study.

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

    International Nuclear Information System (INIS)

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

  15. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.;

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure....... The primary goal of this article is to review the new and interesting magnetic structures which have been discovered in these novel superlattice systems and to consider what implications the observed phases have on our understanding of the underlying microscopic magnetic interactions. In particular......, the effects of the artificial periodicity or compositional modulation, finite layer thickness, and epitaxial strain on the resulting long range magnetic order of Gd-Y, Dy-Y, Ho-Y, Er-Y, and Gd-Dy superlattices are described....

  16. Prophylactic treatment with alkaline phosphatase in cardiac surgery induces endogenous alkaline phosphatase release

    NARCIS (Netherlands)

    Kats, Suzanne; Brands, Ruud; Hamad, Mohamed A. Soliman; Seinen, Willem; Schamhorst, Volkher; Wulkan, Raymond W.; Schoenberger, Jacques P.; van Oeveren, Wim

    2012-01-01

    Introduction: Laboratory and clinical data have implicated endotoxin as an important factor in the inflammatory response to cardiopulmonary bypass. We assessed the effects of the administration of bovine intestinal alkaline phosphatase (bIAP), an endotoxin detoxifier, on alkaline phosphatase levels

  17. Transition from alkaline to calc-alkaline volcanism during evolution of the Paleoproterozoic Francevillian basin of eastern Gabon (Western Central Africa)

    Science.gov (United States)

    Thiéblemont, Denis; Bouton, Pascal; Préat, Alain; Goujou, Jean-Christian; Tegyey, Monique; Weber, Francis; Ebang Obiang, Michel; Joron, Jean Louis; Treuil, Michel

    2014-11-01

    We report new geochemical data for the volcanic and subvolcanic rocks associated with the evolution of the Francevillian basin of eastern Gabon during Paleoproterozoic times (c. 2.1-2 Ga). Filling of this basin has proceeded through four main sedimentary or volcano-sedimentary episodes, namely FA, FB, FC and FD. Volcanism started during the FB episode being present only in the northern part of the basin (Okondja sub-basin). This volcanism is ultramafic to trachytic in composition and displays a rather constant alkaline geochemical signature. This signature is typical of a within-plate environment, consistent with the rift-setting generally postulated for the Francevillian basin during the FB period. Following FB, the FC unit is 10-20 m-thick silicic horizon (jasper) attesting for a massive input of silica in the basin. Following FC, the FD unit is a c. 200-400 m-thick volcano-sedimentary sequence including felsic tuffs and epiclastic rocks. The geochemical signatures of these rocks are totally distinct from those of the FB alkaline lavas. High Th/Ta and La/Ta ratios attest for a calc-alkaline signature and slight fractionation between heavy rare-earth suggests melting at a rather low pressure. Such characteristics are comparable to those of felsic lavas associated with the Taupo zone of New Zealand, a modern ensialic back-arc basin. Following FD, the FE detrital unit is defined only in the Okondja region, probably associated with a late-stage collapse of the northern part of the basin. It is suggested that the alkaline to calc-alkaline volcanic transition reflects the evolution of the Francevillian basin from a diverging to a converging setting, in response to the onset of converging movements in the Eburnean Belt of Central Africa.

  18. Experiments in cold atom optics towards precision atom interferometry

    Science.gov (United States)

    Aveline, David C.

    magnetic field contours of the traps and the dynamics of atoms within those confining potentials. We also controlled the propagation along the atom chip guides by accelerating atoms with longitudinal magnetic gradients, and investigated an atom focusing scheme. While the atom chip wire guides perform a role analogous to optical fibers guiding light waves, "free space" cold atoms offer great opportunity for precision interferometry. We describe a second on-going atom optics experiment that measures gravity gradients using a pair of atom fountain interferometers separated by one meter. We have demonstrated Gravity Gradiometer resolution down to 4x10-9 g/m using a 40 kg test mass. The atomic physics subsystem is described in detail, including the vacuum, cold atom source, optics, magnetic coils and shields, and vibration isolation and compensation. The system is designed to be a compact, robust, transportable instrument, taking strides towards future gravity gradient measurements in the field. In the realm of space applications, there has been interest for micro-gravity science experiments aboard the International Space Station, along with instrument development for gravity mapping of Earth and planetary bodies with satellite-based instruments. Furthermore, there are ground-based applications for gravity imaging of local density distributions, precision measurement of gravity, as well as proposals for redefining the kilogram, detecting gravitational waves and determining the Gravitational constant.

  19. Specific Examples of Hybrid Alkaline Cement

    OpenAIRE

    Fernández-Jiménez Ana; García-Lodeiro Inés; Donatello Shane; Maltseva Olga; Palomo Ángel

    2014-01-01

    Hybrid alkaline cements are obtained by alkali-activating cementitious blends in the Na2O-CaO-SiO2-Al2O3-H2O system. The present paper discusses the results of activating different cementitious blends containing a low OPC clinker content ( 15MPa a 2 days) different alkaline activators were used (liquid and solid). The reaction products obtained were also characterised by XRD, SEM/EDX and 27Al and 29Si NMRMAS. The results showed that the main reaction product was a mix of cementitious gels C-A...

  20. Alkaline Capacitors Based on Nitride Nanoparticles

    Science.gov (United States)

    Aldissi, Matt

    2003-01-01

    High-energy-density alkaline electrochemical capacitors based on electrodes made of transition-metal nitride nanoparticles are undergoing development. Transition- metal nitrides (in particular, Fe3N and TiN) offer a desirable combination of high electrical conductivity and electrochemical stability in aqueous alkaline electrolytes like KOH. The high energy densities of these capacitors are attributable mainly to their high capacitance densities, which, in turn, are attributable mainly to the large specific surface areas of the electrode nanoparticles. Capacitors of this type could be useful as energy-storage components in such diverse equipment as digital communication systems, implanted medical devices, computers, portable consumer electronic devices, and electric vehicles.

  1. Electrochemical behaviour of alkaline copper complexes

    Indian Academy of Sciences (India)

    C L Aravinda; S M Mayanna; V R Muralidharan

    2000-10-01

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

  2. A deposit model for carbonatite and peralkaline intrusion-related rare earth element deposits: Chapter J in Mineral deposit models for resource assessment

    Science.gov (United States)

    Verplanck, Philip L.; Van Gosen, Bradley S.; Seal, Robert R., II; McCafferty, Anne E.

    2014-01-01

    Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. A wide variety of other commodities have been exploited from carbonatites and alkaline igneous rocks including niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other elements enriched in these deposits include manganese, strontium, tantalum, thorium, vanadium, and uranium. Carbonatite and peralkaline intrusion-related rare earth element deposits are presented together in this report because of the spatial, and potentially genetic, association between carbonatite and alkaline rocks. Although these rock types occur together at many locations, carbonatite and peralkaline intrusion-related rare earth element deposits are not generally found together.

  3. Direct determination of total mercury in phosphate rock using alkaline fusion digestion

    Energy Technology Data Exchange (ETDEWEB)

    D’Agostino, Fabio, E-mail: fabio.dagostino@iamc.cnr.it [Institute for Coastal Marine Environment (IAMC) – CNR, Via del Mare 3, 91021 Torretta Granitola (Trapani) (Italy); Oliveri, Elvira [Institute for Coastal Marine Environment (IAMC) – CNR, Via del Mare 3, 91021 Torretta Granitola (Trapani) (Italy); Bagnato, Emanuela [DiSTeM, University of Palermo, Via Archirafi 36, 90123 Palermo (Italy); Falco, Francesca; Mazzola, Salvatore; Sprovieri, Mario [Institute for Coastal Marine Environment (IAMC) – CNR, Via del Mare 3, 91021 Torretta Granitola (Trapani) (Italy)

    2014-12-10

    Highlights: • Determination of total mercury concentration within phosphate rock by alkaline fusion digestion. • Digestion by alkaline fusion salts mixture which melts at 400 °C. • Total Hg determination by atomic absorption spectrophotometry comply with EPA method 7473. • Comparison of Hg recovery between EPA method 7473 and alkaline fusion digestion method. - Abstract: The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, this instrument underestimates Hg concentrations when phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473. Therefore, to improve the recovery of total Hg, we performed alkaline fusion digestion (AFD) directly inside the furnace of the instrument, using BCR(32) as a certified reference material (Moroccan phosphate rock – phosphorite). The salts used for the AFD were a mixture of Na{sub 2}CO{sub 3}, K{sub 2}CO{sub 3} and Li{sub 2}CO{sub 3}, which melt at about 400 °C, due to their ability to form a ternary eutectic and to decompose the phosphorite matrices at 700 °C. By adopting this analytical approach, the Hg recovery in BCR(32) was about 100%, compared to 40% when the reference material was analysed without using the alkaline fusion salt. We suggest that the AFD allowed the decomposition of the sample matrix and that some Hg compounds linked with other functional groups may be transformed in carbonates that sublimate at lower temperatures than other Hg compounds. This original method was tested on a number of different geological samples to compare the differences between the AFD method and the thermal treatment in order to verify the working range and to check the

  4. Atomic secrecy

    International Nuclear Information System (INIS)

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  5. BaClSCN and Na{sub 4}Mg(SCN){sub 6}: two new thiocyanates of the alkaline earth metals; BaClSCN und Na{sub 4}Mg(SCN){sub 6}: zwei neue wasserfreie Thiocyanate der Erdalkalimetalle

    Energy Technology Data Exchange (ETDEWEB)

    Wickleder, C.; Larsen, P. [Koeln Univ. (Germany). Inst. fuer Anorganische Chemie

    2001-06-01

    The reaction of BaCl{sub 2} and NaSCN yielded single crystals of BaClSCN (P 2{sub 1}/m, Z = 2, a = 588.6(1) pm, b = 465.8(1) pm, c = 864.4(2) pm, {beta} = 100.20(3) , R{sub all} = 0.0214). According to X-ray single crystal investigations, the structure consists of anionic SCN{sup -} and Cl{sup -} layers, respectively, alternating in [001] direction. The SCN{sup -}-ions are connected via the N and the S atoms to the cations. Na{sub 4}Mg(SCN){sub 6} (P anti 31c, Z = 2, a = 863.8(1) pm, c = 1399.3(2) pm, R{sub all} = 0.0870), which was obtained from a melt of NaSCN and MgCl{sub 2}, consists of anionic layers with the cations between the sheets. The holes are filled alternatingly by Na{sup +} or Na{sup +} and Mg{sup 2+}. Regarding only the C-atoms of the SCN{sup -} group, the structure can be described as a hexagonal closest packing with the cations occupying 5/6 of the octahedral voids. (orig.)

  6. The Alkaline Diet: Is There Evidence That an Alkaline ph Diet Benefits Health?

    International Nuclear Information System (INIS)

    This review looks at the role of an alkaline diet in health. Pub med was searched looking for articles on ph, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine

  7. The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?

    Directory of Open Access Journals (Sweden)

    Gerry K. Schwalfenberg

    2012-01-01

    Full Text Available This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine.

  8. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  9. Testing the Gravitational Redshift with Atomic Gravimeters?

    CERN Document Server

    Wolf, Peter; Bordé, Christian J; Reynaud, Serge; Salomon, Christophe; Cohen-Tannoudji, Claude

    2011-01-01

    Atom interferometers allow the measurement of the acceleration of freely falling atoms with respect to an experimental platform at rest on Earth's surface. Such experiments have been used to test the universality of free fall by comparing the acceleration of the atoms to that of a classical freely falling object. In a recent paper, M\\"uller, Peters and Chu [Nature {\\bf 463}, 926-929 (2010)] argued that atom interferometers also provide a very accurate test of the gravitational redshift (or universality of clock rates). Considering the atom as a clock operating at the Compton frequency associated with the rest mass, they claimed that the interferometer measures the gravitational redshift between the atom-clocks in the two paths of the interferometer at different values of gravitational potentials. In the present paper we analyze this claim in the frame of general relativity and of different alternative theories, and conclude that the interpretation of atom interferometers as testing the gravitational redshift ...

  10. Persistently increased intestinal fraction of alkaline phosphatase

    DEFF Research Database (Denmark)

    Nathan, E; Baatrup, G; Berg, H;

    1984-01-01

    Persistent elevation of the intestinal fraction of the alkaline phosphatase (API) as an isolated finding has to our knowledge not been reported previously. It was found in a boy followed during a period of 5.5 years. The only symptom was transient periodic fatigue observed at home, but not apparent...... phosphatase activity could be demonstrated....

  11. Use Alkalinity Monitoring to Optimize Bioreactor Performance.

    Science.gov (United States)

    Jones, Christopher S; Kult, Keegan J

    2016-05-01

    In recent years, the agricultural community has reduced flow of nitrogen from farmed landscapes to stream networks through the use of woodchip denitrification bioreactors. Although deployment of this practice is becoming more common to treat high-nitrate water from agricultural drainage pipes, information about bioreactor management strategies is sparse. This study focuses on the use of water monitoring, and especially the use of alkalinity monitoring, in five Iowa woodchip bioreactors to provide insights into and to help manage bioreactor chemistry in ways that will produce desirable outcomes. Results reported here for the five bioreactors show average annual nitrate load reductions between 50 and 80%, which is acceptable according to established practice standards. Alkalinity data, however, imply that nitrous oxide formation may have regularly occurred in at least three of the bioreactors that are considered to be closed systems. Nitrous oxide measurements of influent and effluent water provide evidence that alkalinity may be an important indicator of bioreactor performance. Bioreactor chemistry can be managed by manipulation of water throughput in ways that produce adequate nitrate removal while preventing undesirable side effects. We conclude that (i) water should be retained for longer periods of time in bioreactors where nitrous oxide formation is indicated, (ii) measuring only nitrate and sulfate concentrations is insufficient for proper bioreactor operation, and (iii) alkalinity monitoring should be implemented into protocols for bioreactor management.

  12. pH in atomic scale simulations of electrochemical interfaces

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Chan, Karen; Ahmed, Rizwan;

    2013-01-01

    Electrochemical reaction rates can strongly depend on pH, and there is increasing interest in electrocatalysis in alkaline solution. To date, no method has been devised to address pH in atomic scale simulations. We present a simple method to determine the atomic structure of the metal|solution in......Electrochemical reaction rates can strongly depend on pH, and there is increasing interest in electrocatalysis in alkaline solution. To date, no method has been devised to address pH in atomic scale simulations. We present a simple method to determine the atomic structure of the metal......|solution interface at a given pH and electrode potential. Using Pt(111)|water as an example, we show the effect of pH on the interfacial structure, and discuss its impact on reaction energies and barriers. This method paves the way for ab initio studies of pH effects on the structure and electrocatalytic activity...

  13. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  14. The effects of alkaline earth metal ions and halogen ions on the chromium oxide activities in alkaline earth metal oxide-halide-Cr2O3 system fluxes

    Science.gov (United States)

    Li, Lian-Fu; Jiang, Mao-Fa; Wang, Wen-Zhong; Chen, Zhao-Ping

    2000-06-01

    The solid electrolyte cell — Mo|Cr + Cr2O3‖ZrO2(MgO)‖{Cu-Cr}alloy + (Cr2O3)fluxes|Mo+ is used at 1673 K to determine Cr2O3 activities in MO-MX 2-Cr2O3 (M = Ca2+, Ba2-, X = F- or Cl-) ternary fluxes, which are in equilibrium with the copper-chromium binary alloy. The ternary isothermal phase diagrams of CaO-CaF2-Cr2O3 and BaO-BaCl2-Cr2O3 system fluxes are inferred on the basis of the experimental results and binary phase diagrams. The results indicate that Cr2O3 activities in all fluxes always decrease with the increase of the X MO /X MX2 ratio. Partial replacement of BaO in BaO-BaF2-Cr2O3 fluxes by CaO is acceptable for economy and efficiency considerations. At the same time, partial substitution of BaO for CaO in CaO-CaF2-Cr2O3 fluxes is advantageous for phosphorus removal and chromium retention as a result of the increased Cr2O3 activities, increased basicities, and widening of the liquid zones. Compared to those in BaO-BaF2-Cr2O3 fluxes, Cr2O3 activities in CaO-CaF2-Cr2O3 fluxes approximately follow the same curve as the former, although the position and the width of the liquid zones are considerably different, and activities in BaO-BaCl2-Cr2O3 fluxes are higher at the lower Cr2O3 content, or vice versa. The activity coefficients of Cr2O3 in the fluxes decrease with the increase of the X MO /X MX 2 ratios.

  15. Alkaline regenerative fuel cell energy storage system for manned orbital satellites

    Science.gov (United States)

    Martin, R. E.; Gitlow, B.; Sheibley, D. W.

    1982-01-01

    It is pointed out that the alkaline regenerative fuel cell system represents a highly efficient, lightweight, reliable approach for providing energy storage in an orbiting satellite. In addition to its energy storage function, the system can supply hydrogen and oxygen for attitude control of the satellite and for life support. A summary is presented of the results to date obtained in connection with the NASA-sponsored fuel cell technology advancement program, giving particular attention to the requirements of the alkaline regenerative fuel cell and the low-earth mission. Attention is given to system design guidelines, weight considerations, gold-platinum cathode cell performance, matrix development, the electrolyte reservoir plate, and the cyclical load profile tests.

  16. Spin-orbit coupled two-electron Fermi gases of ytterbium atoms

    CERN Document Server

    Song, Bo; Zhang, Shanchao; Zou, Yueyang; Haciyev, Elnur; Huang, Wei; Liu, Xiong-Jun; Jo, Gyu-Boong

    2016-01-01

    We demonstrate the spin-orbit coupling (SOC) in a two-electron Fermi gas of $^{173}$Yb atoms by coupling two hyperfine ground states via the two-photon Raman transition. Due to the SU($N$) symmetry of the $^1$S$_0$ ground-state manifold which is insensitive to external magnetic field, an optical AC Stark effect is applied to split the ground spin states and separate an effective spin-1/2 subspace out from other hyperfine levels for the realization of SOC. With a momentum-dependent spin-orbit gap being suddenly opened by switching on the Raman transition, the dephasing of spin dynamics is observed, as a consequence of the momentum-dependent Rabi oscillations. Moreover, the momentum asymmetry of the spin-orbit coupled Fermi gas is also examined after projection onto the bare spin state and the corresponding momentum distribution is measured for different two-photon detuning. The realization of SOC for Yb fermions may open a new avenue to the study of novel spin-orbit physics with alkaline-earth-like atoms.

  17. Atomic arias

    Science.gov (United States)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  18. Atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Livingston, A.E.; Kukla, K.; Cheng, S. [Univ. of Toledo, OH (United States)] [and others

    1995-08-01

    In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.

  19. Clock Synchronisation in the Vicinity of the Earth

    OpenAIRE

    Goy, Francois

    1997-01-01

    The transmission time of an electromagnetic signal in the vicinity of the earth is calculated to c-2 and contains an orbital Sagnac term. On earth, the synchronisation of the Barycentric Coordinate Time (TCB) can be realised by atomic clocks, but not the one of Geocentric Coordinate Time (TCG). The principle of equivalence is discussed.

  20. Theoretical study of the alkaline hydrolysis of an aza-β-lactam derivative of clavulanic acid

    Science.gov (United States)

    Garcías, Rafael C.; Coll, Miguel; Donoso, Josefa; Muñoz, Francisco

    2003-04-01

    DFT calculations based on the hybrid functional B3LYP/6-31+G * were used to study the alkaline hydrolysis of an aza-clavulanic acid, which results from the substitution of the carbon atom at position 6 in clavulanic acid by a nitrogen atom. The presence of the nitrogen atom endows the compound with special properties; in fact, once formed, the tetrahedral intermediate can evolve with cleavage of the N 4-C 7 or N 6-C 7 bond, which obviously leads to different reaction products. These differential bond cleavages may play a central role in the inactivation of β-lactamases, so the compound may be a powerful inactivator of these enzymes.

  1. Specific Examples of Hybrid Alkaline Cement

    Directory of Open Access Journals (Sweden)

    Fernández-Jiménez Ana

    2014-04-01

    Full Text Available Hybrid alkaline cements are obtained by alkali-activating cementitious blends in the Na2O-CaO-SiO2-Al2O3-H2O system. The present paper discusses the results of activating different cementitious blends containing a low OPC clinker content ( 15MPa a 2 days different alkaline activators were used (liquid and solid. The reaction products obtained were also characterised by XRD, SEM/EDX and 27Al and 29Si NMRMAS. The results showed that the main reaction product was a mix of cementitious gels C-A-S-H and (N,C-A-S-H, and that their relative proportions were strongly influenced by the calcium content in the initial binder

  2. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

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

    2013-01-01

    Alkaline electrolyzers have proven to operate reliable for decades on a large scale, but in order to become commercially attractive and compete against conventional technologies for hydrogen production, the production and investment costs have to be reduced. This may occur by increasing the...... operational temperature and pressure to produce pressurized hydrogen at high rate (m3 H2·h-1·m-2 cell area) and high electrical efficiency. This work describes an exploratory technical study of the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures...... SrTiO3 was used for immobilization of aqueous KOH solutions. Electrolysis cells with this electrolyte and metal foam based gas diffusion electrodes were successfully demonstrated at temperatures up to 250 °C at 40 bar. Different electro-catalysts were tested in order to reduce the oxygen and hydrogen...

  3. Earth Abundant Element Type I Clathrate Phases

    Directory of Open Access Journals (Sweden)

    Susan M. Kauzlarich

    2016-08-01

    Full Text Available Earth abundant element clathrate phases are of interest for a number of applications ranging from photovoltaics to thermoelectrics. Silicon-containing type I clathrate is a framework structure with the stoichiometry A8-xSi46 (A = guest atom such as alkali metal that can be tuned by alloying and doping with other elements. The type I clathrate framework can be described as being composed of two types of polyhedral cages made up of tetrahedrally coordinated Si: pentagonal dodecahedra with 20 atoms and tetrakaidecahedra with 24 atoms in the ratio of 2:6. The cation sites, A, are found in the center of each polyhedral cage. This review focuses on the newest discoveries in the group 13-silicon type I clathrate family: A8E8Si38 (A = alkali metal; E = Al, Ga and their properties. Possible approaches to new phases based on earth abundant elements and their potential applications will be discussed.

  4. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  5. CARINA alkalinity data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    A. Velo

    2009-08-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic.

    These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values.

    Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg−1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  6. Alkaline leaching of iron and steelmaking dust

    OpenAIRE

    Stafanova, Anna; Aromaa, Jari

    2012-01-01

    Steel production generates significant quantities of dust and sludge in blast furnaces (BF),basic oxygen furnaces (BOF), and electric arc furnaces (EAF). These dusts contain toxicelements, such as heavy metals, and are thus classified as harmful waste making the disposalof them expensive. In addition, direct recycling of dust back to steel production is hindered dueto the presence of zinc. In this literature survey the alkaline leaching of zinc from iron and steelmaking dusts isreviewed. T...

  7. Theory of a metrology for the earths magnetic field based on the resonance of polarised atomic nuclei (1962); Theorie d'une metrologie du champ magnetique terrestre basee sur la resonance de noyaux atomiques polarises (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, G. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1961-06-15

    The problems presented by the metrology of the earths field are studied from two points of view. a. The first, purely physical, concerns the study of NMR transducers in their role for the transformation of the magnetic field into a frequency. The possibilities and limitations are outlined. The use of an equivalent model is introduced systematically in the considerations of NMR phenomena, this makes it possible to treat all problems of interaction between a spin system and an electric detection system in a unified form. b. The other point of view concerns the restitution of the nuclear signal frequency in the form of a directly perceptible observable. The treatment of information is considered from a statistical angle, which leads to the study of an optimisation process concerning the linearization of the measurement as well as the minimisation of noise effects. (author) [French] Les problemes que pose la metrologie du champ terrestre sont etudies sous un double aspect: a. L'un, purement physique, concerne l'etude des traducteurs a RMN dans leur role de transformation du champ magnetique en une frequence. On en degage les possibilites et les limitations. L'emploi d'un modele equivalent est introduit de maniere systematique pour rendre compte des phenomenes de RMN, ce qui permet de traiter sous forme unifiee tous les problemes d'interaction entre un systeme de spins et un systeme electrique de detection. b. L'autre aspect concerne la restitution de la frequence du signal nucleaire sous la forme d'une observable directement perceptible. On considere le traitement de l'information sous l'aspect statistique, ce qui amene a etudier un processus d'optimisation concernant la linearisation de la mesure aussi bien que la minimisation des effets des bruits. (auteur)

  8. Fe(III), Cr(VI), and Fe(III) mediated Cr(VI) reduction in alkaline media using a Halomonas isolate from Soap Lake, Washington.

    Science.gov (United States)

    VanEngelen, Michael R; Peyton, Brent M; Mormile, Melanie R; Pinkart, Holly C

    2008-11-01

    Hexavalent chromium is one of the most widely distributed environmental contaminants. Given the carcinogenic and mutagenic consequences of Cr(VI) exposure, the release of Cr(VI) into the environment has long been a major concern. While many reports of microbial Cr(VI) reduction are in circulation, very few have demonstrated Cr(VI) reduction under alkaline conditions. Since Cr(VI) exhibits higher mobility in alkaline soils relative to pH neutral soils, and since Cr contamination of alkaline soils is associated with a number of industrial activities, microbial Cr(VI) reduction under alkaline conditions requires attention.Soda lakes are the most stable alkaline environments on earth, and contain a wide diversity of alkaliphilic organisms. In this study, a bacterial isolate belonging to the Halomonas genus was obtained from Soap Lake, a chemically stratified alkaline lake located in central Washington State. The ability of this isolate to reduce Cr(VI) and Fe(III) was assessed under alkaline (pH = 9), anoxic, non-growth conditions with acetate as an electron donor. Metal reduction rates were quantified using Monod kinetics. In addition, Cr(VI) reduction experiments were carried out in the presence of Fe(III) to evaluate the possible enhancement of Cr(VI) reduction rates through electron shuttling mechanisms. While Fe(III) reduction rates were slow compared to previously reported rates, Cr(VI) reduction rates fell within range of previously reported rates. PMID:18401687

  9. Alkaline and ultrasound assisted alkaline pretreatment for intensification of delignification process from sustainable raw-material.

    Science.gov (United States)

    Subhedar, Preeti B; Gogate, Parag R

    2014-01-01

    Alkaline and ultrasound-assisted alkaline pretreatment under mild operating conditions have been investigated for intensification of delignification. The effect of NaOH concentration, biomass loading, temperature, ultrasonic power and duty cycle on the delignification has been studied. Most favorable conditions for only alkaline pretreatment were alkali concentration of 1.75 N, solid loading of 0.8% (w/v), temperature of 353 K and pretreatment time of 6 h and under these conditions, 40.2% delignification was obtained. In case of ultrasound-assisted alkaline approach, most favorable conditions obtained were alkali concentration of 1N, paper loading of 0.5% (w/v), sonication power of 100 W, duty cycle of 80% and pretreatment time of 70 min and the delignification obtained in ultrasound-assisted alkaline approach under these conditions was 80%. The material samples were characterized by FTIR, SEM, XRD and TGA technique. The lignin was recovered from solution by precipitation method and was characterized by FTIR, GPC and TGA technique.

  10. Water removal studies on high power hydrogen-oxygen fuel cells with alkaline electrolytes

    Science.gov (United States)

    Kordesch, K.; Oliveira, J. C. T.; Gruber, Ch.; Winkler, G.

    1989-08-01

    Research in verification of bipolar fuel cell design, containing mass-produceable all-carbon electrodes which can be used in alkaline or acidic cells with liquid or immobilized (matrix) electrolytes, is described. Spin-offs from the research related to the Hermes manned spaceplane could be useful for applications on Earth. Peak-power plants, electric vehicles and storage devices used in combination with renewable energy sources could all benefit from the research. A subsequent investigation of water transpiration properties of carbon electrodes is described.

  11. A study on alkaline heat treated Mg-Ca alloy for the control of the biocorrosion rate.

    Science.gov (United States)

    Gu, X N; Zheng, W; Cheng, Y; Zheng, Y F

    2009-09-01

    To reduce the biocorrosion rate by surface modification, Mg-Ca alloy (1.4wt.% Ca content) was soaked in three alkaline solutions (Na(2)HPO(4), Na(2)CO(3) and NaHCO(3)) for 24h, respectively, and subsequently heat treated at 773K for 12h. Scanning electron microscopy and energy-dispersive spectroscopy results revealed that magnesium oxide layers with the thickness of about 13, 9 and 26microm were formed on the surfaces of Mg-Ca alloy after the above different alkaline heat treatments. Atomic force microscopy showed that the surfaces of Mg-Ca alloy samples became rough after three alkaline heat treatments. The in vitro corrosion tests in simulated body fluid indicated that the corrosion rates of Mg-Ca alloy were effectively decreased after alkaline heat treatments, with the following sequence: NaHCO(3) heatedalkaline heat treated Mg-Ca alloy samples induced toxicity to L-929 cells during 7days culture.

  12. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  13. Determination of Hexavalent Chromium in the Solid Waste by Alkaline Digestion-Flame Atomic Absorption Spectrophotometry%碱消解-火焰原子吸收分光光度法测定固体废物中的六价铬

    Institute of Scientific and Technical Information of China (English)

    季蕴佳; 周勤; 方爱红; 楼成林

    2012-01-01

    A method for determining Cr( VI) in the solid waste by alkali digestion-atomic absorption spec-trophotometry was developed. The pre-treatment conditions were discussed. The optimum digestion temperature of the samples should be at 90 ℃~95 ℃, the digestion time was 60 minutes, and pH of the digestion fluid was 9.0 ±0.2. The detection limit and reliable quantitation limit of this method were 0. 05 mg/kg and 0.20 mg/kg respectively, the RSD of actual sample on the different matrix was 1.4%~13.0% , spiking recovery was 93 %~ 130%.%采用碱消解-火焰原子吸收分光光度法测定固体废物中的六价铬,样品消解温度控制在90℃~95℃范围内,消解时间为1h,消解液pH值调节至9.0土0.2.方法检出限与测定下限分别为0.05 mg/kg与0.20 mg/kg,对不同基体实际样品平行测定的RSD为1.4%~13.O%,加标回收率为93%~ 130%.

  14. RES Hydrogen: efficient pressurised alkaline electrolysers

    DEFF Research Database (Denmark)

    Bowen, Jacob R.; Bentzen, Janet Jonna; Jørgensen, Peter Stanley;

    The RESelyser project addresses issues associated with coupling alkaline electrolysis to renewable energy sources such as electrode stability and gas purity by implementing improved electrodes and a new separator membrane concept. The project aims to improve performance, operation pressure and...... reduce system cost. The project supports DTU Energy's activities on electrodes within the larger FCH-JU project. The overall project demonstrated: improved electrode efficiency also during cyclic operation, safe gas purity at a system pressure of 30 bar, 10 kW stack operation and estimated system costs...

  15. Alkaline carbonates in blast furnace process

    Directory of Open Access Journals (Sweden)

    P. Besta

    2014-10-01

    Full Text Available The production of iron in blast furnaces is a complex of physical, chemical and mechanical processes. The input raw materials contain not only metallic components, but also a number of negative elements. The most important negative elements include alkaline carbonates. They can significantly affect the course of the blast furnace process and thus the overall performance of the furnace. As a result of that, it is essential to accurately monitor the alkali content in the blast furnace raw materials. The article analyzes the alkali content in input and output raw materials and their impact on the blast furnace process.

  16. Pitting corrosion of friction stir welded aluminum alloy thick plate in alkaline chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Xu Weifeng, E-mail: xwf1982@mail.nwpu.edu.c [School of Materials and Engineering, Northwestern Polytechnical University, Xi' an 710072 (China); Liu Jinhe; Zhu Hongqiang [School of Materials and Engineering, Northwestern Polytechnical University, Xi' an 710072 (China)

    2010-03-01

    The pitting corrosion of different positions (Top, Middle and Bottom) of weld nugget zone (WNZ) along thickness plate in friction stir welded 2219-O aluminum alloy in alkaline chloride solution was investigated by using open circuit potential, cyclic polarization, scanning electron microscopy and atomic force microscope. The results indicate that the material presents significant passivation, the top has highest corrosion potential, pitting potential and re-passivation potential compared with the bottom and base material. With the increase of traverse speed from 60 to 100 mm/min or rotary speed from 500 to 600 rpm, the corrosion resistance decreases.

  17. Pitting corrosion of friction stir welded aluminum alloy thick plate in alkaline chloride solution

    International Nuclear Information System (INIS)

    The pitting corrosion of different positions (Top, Middle and Bottom) of weld nugget zone (WNZ) along thickness plate in friction stir welded 2219-O aluminum alloy in alkaline chloride solution was investigated by using open circuit potential, cyclic polarization, scanning electron microscopy and atomic force microscope. The results indicate that the material presents significant passivation, the top has highest corrosion potential, pitting potential and re-passivation potential compared with the bottom and base material. With the increase of traverse speed from 60 to 100 mm/min or rotary speed from 500 to 600 rpm, the corrosion resistance decreases.

  18. Long-term landscape evolution of the southeast Brazilian highlands: comparison of two alkaline intrusions areas

    Science.gov (United States)

    Doranti Tiritan, Carolina; Hackspacher, Peter Christian; Glasmacher, Ulrich Anton

    2016-04-01

    . In the SSI area the crystalline basement registered ages 121.1±11.5 Ma and 49.4±4.8 while the alkaline stocks ages ranges 112.5±13; 91.1±11.2Ma; 89.4±13.4 88.2±8.5; 71.3±7.9. The results shows that the main difference between the areas is that PCAM region register older history then the coastal area of SSI, where thermal history starts register cooling event after the South Atlantic rifting process, while in the PCAM area register a previous history, since Carboniferous. The age-elevation relationship shows that the ages decrease systematically with increasing elevation with a break-in-slope near the 150Ma, 80Ma and around 50Ma, which means that the landscape evolution can be associated with several distinct exhumation events at the South American passive continental margin, which include the Gondwana break-up, the Late Cretaceous alkaline magmatism, and the Cenozoic evolution of a N-S trending continental graben system. We are thankful to CAPES/PROBRAL/ processo 12809/13-6, Marli Carina Siqueira Ribeiro, IGCE-UNESP; Earth Sciences Institut, Heidelberg University; References DORANTI-TIRITAN, C. , et al (2014) The Use of the Stream Length-Gradient Index in Morphotectonic Analysis of Drainage Basins in Poços de Caldas Plateau, SE Brazil. International Journal of Geosciences, 5, 1383-1394. doi: 10.4236/ijg.2014.511112 HACKSPACHER, P.C; et al. (2004) Consolidation and Break-Up of The South American Platform in Southeastern Brazil: Tectonothermal and Denudation Histories. Gondwana Research -N°1, P. 91 -101.

  19. Antiferromagnetic topological insulators in cold atomic gases

    OpenAIRE

    Essin, Andrew M.; Gurarie, Victor

    2011-01-01

    We propose a spin-dependent optical lattice potential that realizes a three-dimensional antiferromagnetic topological insulator in a gas of cold, two-state fermions such as alkaline earths, as well as a model that describes the tight-binding limit of this potential. We discuss the physically observable responses of the gas that can verify the presence of this phase. We also point out how this model can be used to obtain two-dimensional flat bands with nonzero Chern number.

  20. Proximity effects in cold gases of multiply charged atoms (Review)

    Science.gov (United States)

    Chikina, I.; Shikin, V.

    2016-07-01

    Possible proximity effects in gases of cold, multiply charged atoms are discussed. Here we deal with rarefied gases with densities nd of multiply charged (Z ≫ 1) atoms at low temperatures in the well-known Thomas-Fermi (TF) approximation, which can be used to evaluate the statistical properties of single atoms. In order to retain the advantages of the TF formalism, which is successful for symmetric problems, the external boundary conditions accounting for the finiteness of the density of atoms (donors), nd ≠ 0, are also symmetrized (using a spherical Wigner-Seitz cell) and formulated in a standard way that conserves the total charge within the cell. The model shows that at zero temperature in a rarefied gas of multiply charged atoms there is an effective long-range interaction Eproxi(nd), the sign of which depends on the properties of the outer shells of individual atoms. The long-range character of the interaction Eproxi is evaluated by comparing it with the properties of the well-known London dispersive attraction ELond(nd) 0 and for the alkali and alkaline-earth elements Eproxi theory through the temperature dependence of the different versions of Eproxi. The anomaly in the thermal proximity effect shows up in the following way: for T ≠ 0 there is no equilibrium solution of TS statistics for single multiply charged atoms in a vacuum when the effect is present. Instability is suppressed in a Wigner-Seitz model under the assumption that there are no electron fluxes through the outer boundary R3 ∝ n-1d of a Wigner-Seitz cell. Eproxi corresponds to the definition of the correlation energy in a gas of interacting particles. This review is written so as to enable comparison of the results of the TF formalism with the standard assumptions of the correlation theory for classical plasmas. The classic example from work on weak solutions (including charged solutions)—the use of semi-impermeable membranes for studies of osmotic pressure—is highly appropriate for

  1. Proximity effects in cold gases of multiply charged atoms (Review)

    Science.gov (United States)

    Chikina, I.; Shikin, V.

    2016-07-01

    Possible proximity effects in gases of cold, multiply charged atoms are discussed. Here we deal with rarefied gases with densities nd of multiply charged (Z ≫ 1) atoms at low temperatures in the well-known Thomas-Fermi (TF) approximation, which can be used to evaluate the statistical properties of single atoms. In order to retain the advantages of the TF formalism, which is successful for symmetric problems, the external boundary conditions accounting for the finiteness of the density of atoms (donors), nd ≠ 0, are also symmetrized (using a spherical Wigner-Seitz cell) and formulated in a standard way that conserves the total charge within the cell. The model shows that at zero temperature in a rarefied gas of multiply charged atoms there is an effective long-range interaction Eproxi(nd), the sign of which depends on the properties of the outer shells of individual atoms. The long-range character of the interaction Eproxi is evaluated by comparing it with the properties of the well-known London dispersive attraction ELond(nd) 0 and for the alkali and alkaline-earth elements Eproxi thermal decay are interesting in themselves as they determine the important phenomenon of dissociation of neutral complexes into charged fragments. This phenomenon appears consistently in the TF theory through the temperature dependence of the different versions of Eproxi. The anomaly in the thermal proximity effect shows up in the following way: for T ≠ 0 there is no equilibrium solution of TS statistics for single multiply charged atoms in a vacuum when the effect is present. Instability is suppressed in a Wigner-Seitz model under the assumption that there are no electron fluxes through the outer boundary R3 ∝ n-1d of a Wigner-Seitz cell. Eproxi corresponds to the definition of the correlation energy in a gas of interacting particles. This review is written so as to enable comparison of the results of the TF formalism with the standard assumptions of the correlation theory for

  2. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge...

  3. EarthKAM

    Data.gov (United States)

    National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...

  4. The Origin of Sulfur Tolerance in Supported Platinum Catalysts: The Relationship between Structural and Catalytic Properties in Acidic and Alkaline Pt/LTL.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Miller, J.T.

    1996-01-01

    The reactivity, structure, and sulfur tolerance is compared for platinum supported on acidic and alkaline LTL zeolite. In the absence of sulfur, EXAFS spectroscopy indicates that small metallic platinum particles of approximately 6 to 14 atoms/cluster are present. The TOF for neopentane hydrogenolys

  5. Alkaline chemistry of transuranium elements and technetium and the treatment of alkaline radioactive wastes

    International Nuclear Information System (INIS)

    Goal of this survey is to generalize the known data on fundamental physical-chemical properties of TRUs and Tc, methods for their isolation, and to provide recommendations that will be useful for partitioning them from alkaline high-level wastes

  6. Alkaline chemistry of transuranium elements and technetium and the treatment of alkaline radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, C.H. [Westinghouse Hanford Co., Richland, WA (United States); Peretrukhin, V.F.; Shilov, V.P.; Pikaev, A.K. [Russian Academy of Sciences (Russian Federation). Inst. of Physical Chemistry

    1995-05-01

    Goal of this survey is to generalize the known data on fundamental physical-chemical properties of TRUs and Tc, methods for their isolation, and to provide recommendations that will be useful for partitioning them from alkaline high-level wastes.

  7. Low serum alkaline phosphatase activity in Wilson's disease.

    Science.gov (United States)

    Shaver, W A; Bhatt, H; Combes, B

    1986-01-01

    Low values for serum alkaline phosphatase activity were observed early in the course of two patients with Wilson's disease presenting with the combination of severe liver disease and Coombs' negative acute hemolytic anemia. A review of other cases of Wilson's disease revealed that 11 of 12 patients presenting with hemolytic anemia had values for serum alkaline phosphatase less than their respective sex- and age-adjusted mean values; in eight, serum alkaline phosphatase activity was less than the lower value for the normal range of the test. Low values for serum alkaline phosphatase were much less common in Wilson's disease patients with more chronic forms of presentation. Copper added in high concentration to serum in vitro did not have an important effect on serum alkaline phosphatase activity. The mechanism responsible for the decrease in serum alkaline phosphatase activity in patients is uncertain.

  8. DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.

    Energy Technology Data Exchange (ETDEWEB)

    SUTHERLAND,B.M.; BENNETT,P.V.; SUTHERLAND, J.C.

    2004-03-24

    Physical and chemical agents in the environment, those used in clinical applications, or encountered during recreational exposures to sunlight, induce damages in DNA. Understanding the biological impact of these agents requires quantitation of the levels of such damages in laboratory test systems as well as in field or clinical samples. Alkaline gel electrophoresis provides a sensitive (down to {approx} a few lesions/5Mb), rapid method of direct quantitation of a wide variety of DNA damages in nanogram quantities of non-radioactive DNAs from laboratory, field, or clinical specimens, including higher plants and animals. This method stems from velocity sedimentation studies of DNA populations, and from the simple methods of agarose gel electrophoresis. Our laboratories have developed quantitative agarose gel methods, analytical descriptions of DNA migration during electrophoresis on agarose gels (1-6), and electronic imaging for accurate determinations of DNA mass (7-9). Although all these components improve sensitivity and throughput of large numbers of samples (7,8,10), a simple version using only standard molecular biology equipment allows routine analysis of DNA damages at moderate frequencies. We present here a description of the methods, as well as a brief description of the underlying principles, required for a simplified approach to quantitation of DNA damages by alkaline gel electrophoresis.

  9. Advanced inorganic separators for alkaline batteries

    Science.gov (United States)

    Sheibley, D. W. (Inventor)

    1982-01-01

    A flexible, porous battery separator comprising a coating applied to a porous, flexible substrate is described. The coating comprises: (1) a thermoplastic rubber-based resin which is insoluble and unreactive in the alkaline electrolyte; (2) a polar organic plasticizer which is reactive with the alkaline electrolyte to produce a reaction product which contains a hydroxyl group and/or a carboxylic acid group; and (3) a mixture of polar particulate filler materials which are unreactive with the electrolyte, the mixture comprising at least one first filler material having a surface area of greater than 25 meters sq/gram, at least one second filler material having a surface area of 10 to 25 sq meters/gram, wherein the volume of the mixture of filler materials is less than 45% of the total volume of the fillers and the binder, the filler surface area per gram of binder is about 20 to 60 sq meters/gram, and the amount of plasticizer is sufficient to coat each filler particle. A method of forming the battery separator is also described.

  10. The effect of alkaline agents on retention of EOR chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, P.B.

    1991-07-01

    This report summarizes a literature survey on how alkaline agents reduce losses of surfactants and polymers in oil recovery by chemical injection. Data are reviewed for crude sulfonates, clean anionic surfactants, nonionic surfactants, and anionic and nonionic polymers. The role of mineral chemistry is briefly described. Specific effects of various alkaline anions are discussed. Investigations needed to improve the design of alkaline-surfactant-polymer floods are suggested. 62 refs., 28 figs., 6 tabs.

  11. A Special Issue (Part-II): Mafic-ultramafic rocks and alkaline-carbonatitic magmatism and associated hydrothermal mineralization - dedication to Lia Nikolaevna Kogarko

    Science.gov (United States)

    Kogarko, Lia N.; Gwalani, Lalchand G.; Downes, Peter J.; Randive, Kirtikumar R.

    2015-10-01

    This is the second part of a two-volumespecial issue of Open Geoscience (formerly Central European Journal of Geosciences) that aims to be instrumental in providing an update of Mafic-Ultramafic Rocks and Alkaline- Carbonatitic Magmatism and Associated Hydrothermal Mineralization. Together, these two volumes provide a detailed and comprehensive coverage of the subjects that are relevant to the research work of P.Comin-Chiaramonti (Italy) and LiaN. Kogarko (Russia) towhomPart-I and Part- II have been respectively dedicated. To a significant extent, the development of advanced sampling technologies related to alkaline and carbonatitic magmatism by Lia N. Kogarko, has allowed geoscientists to measure and sample the deep crust of the planet not only for the exploration for the mineral deposits, but also to answer basic scientific questions about the origin and evolution of alkaline rocks (kimberlites, lamproites and related rocks associated with carbonatites). The papers presented in this Part-II of the special issue cover the petrology and geochemistry of the rocks collected from the surface and penetrated by drilling. Lia Kogarko proposed a new theory for the evolution of alkaline magmatism in the geological history of the Earth - that the appearance of alkaline magmatism at the Archaean-Proterozoic boundary (~2.5 - 2.7 Ga), and its growing intensity, was related to changes in the geodynamic regime of the Earth and oxidation of the mantle due to mantle-crust interaction.

  12. Effect of Alkaline-Stabilised Sewage Sludge on Extractable Organic Carbon and Copper in Soils

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An incubation experiment was conducted to evaluate the potential for water contamination with sludgederived organic substances and copper following land application of alkaline-stabilised sewage sludge. Two contrasting sludge-amended soils were studied. Both soils were previously treated with urban and rural alkaline biosolids separately at sludge application rates of 0, 30 and 120 t ha-1 fresh product. The air-dried soil/sludge mixtures were wetted with distilled water, maintained at 40 % of water-holding capacity and equilibrated for three weeks at 4 ℃ before extraction. Subsamples were extracted with either distilled water or 0.5 mol L-1 K2SO4 solution. The concentrations of organic C in the aqueous and chemical extracts were determined directly with a total organic carbon (TOC) analyser. The concentrations of Cu in the two extracts were also determined by atomic absorption spectrophotometry. The relationship between the two extractable organic C fractions was examined, together with that between extractable organic C concentration and extractable Cu concentration. Application of alkaline biosolids increased the concentrations of soil mobile organic substances and Cu. The results are discussed in terms of a possible increase in the potential for leaching of sludge-derived organics and Cu in the sludge-amended soils

  13. Factors determining the structure of Au, Ag and Cr thin layers deposited on alkaline halogen substrates

    International Nuclear Information System (INIS)

    Metal thin layer deposited on dielectric substrates, in general, and on alkaline halogen substrates, in particular, have been thoroughly studied in order to make clear the phenomenology of the formation and development processes, to set out fundamental factors in determining their structure and to determine optimum conditions for the obtaining of monocrystal thin layers or metastable structured thin layers in view of their practical applications. Starting from a systematic programme of experimental investigations, an attempt has been made to investigate the influence of substrate composition, of defects within alkaline halogen substrates and of deposition conditions on the orientated formation and development of Au layer and on the formation of metastable Cr-delta structures in the case of thin Cr layers. A systematic study on the influence of deposition conditions and on alkaline halogen substrates with colloidal centres is carried out in view of elaborating a method for the development of monocrystal Au layers for ''channeling targets''. A correlation between characteristic parameters which define the atomic theory of nucleation including deposition conditions and material parameters, Au parameters for the case of epitaxial layers deposited on KBr, KCl and NaCl substrates has been attempted. (author)

  14. From Geochemistry to Biochemistry: Simulating Prebiotic Chemistry Driven by Geochemical Gradients in Alkaline Hydrothermal Vents

    Science.gov (United States)

    Barge, Laurie

    2016-07-01

    Planetary water-rock interfaces generate energy in the form of redox, pH, and thermal gradients, and these disequilibria are particularly focused in hydrothermal vent systems where the reducing, heated hydrothermal fluid feeds back into the more oxidizing ocean. Alkaline hydrothermal vents have been proposed as a likely location for the origin of life on the early Earth due to various factors: including the hydrothermal pH / Eh gradients that resemble the ubiquitous electrical / proton gradients in biology, the catalytic hydrothermal precipitates that resemble inorganic catalysts in enzymes, and the presence of electron donors and acceptors in hydrothermal systems (e.g. H2 + CH4 and CO2) that are thought to have been utilized in the earliest metabolisms. Of particular importance for the emergence of metabolism are the mineral "chimneys" that precipitate at the vent fluid / seawater interface. Hydrothermal chimneys are flow-through chemical reactors that form porous and permeable inorganic membranes transecting geochemical gradients; in some ways similar to biological membranes that transect proton / ion gradients and harness these disequilibria to drive metabolism. These emergent chimney structures in the far-from-equilibrium system of the alkaline vent have many properties of interest to the origin of life that can be simulated in the laboratory: for example, they can generate electrical energy and drive redox reactions, and produce catalytic minerals (in particular the metal sulfides and iron oxyhydroxides - "green rust") that can facilitate chemical reactions towards proto-metabolic cycles and biosynthesis. Many of the factors prompting interest in alkaline hydrothermal vents on Earth may also have been present on early Mars, or even presently within icy worlds such as Europa or Enceladus - thus, understanding the disequilibria and resulting prebiotic chemistry in these systems can be of great use in assessing the potential for other environments in the Solar

  15. Theoretical Study of the Properties of the Type II Clathrate A^xSn^136, (A = alkali atom; 0 <= x <= 24)

    Science.gov (United States)

    Xue, Dong; Higgins, Craig; Myles, Charley

    2012-10-01

    Motivated by recent experimental and theoretical interest in the x dependence of the properties of the Si and Ge-based Type II clathrate materials A^xSi^136 and A^xGe^136 (A = alkali atom) [1,2] we are carrying out a systematic theoretical study of the properties of the Sn-based Type II clathrate system A^xSn^136. Type II clathrates have cage-like lattices in which Si, Ge, or Sn atoms are tetrahedrally-coordinated and sp3 covalently bonded. The cages can contain ``guests''; usually alkali or alkaline earth atoms. These materials are particularly interesting because of their potential use as thermoelectrics. Recent powder X-ray diffraction experiments have found the very interesting result that, for increasing x in the range 0 10.1021/cg200756r[0pt] [2] M. Beekman, E. Nenghabi, K. Biswas, C. Myles, M. Baitinger, Y. Grin, G.S. Nolas, Inorg. Chem. 49 2010, DOI: 10.1021/ic1005049

  16. Atom interferometer as a selective sensor of rotation or gravity

    CERN Document Server

    Dubetsky, B

    2006-01-01

    In the presence of Earth gravity and gravity-gradient forces, centrifugal and Coriolis forces caused by the Earth rotation, the phase of the time-domain atom interferometers is calculated with accuracy up to the terms proportional to the fourth degree of the time separation between pulses. We considered double-loop atom interferometers and found appropriate condition to eliminate their sensitivity to acceleration to get atomic gyroscope, or to eliminate the sensitivity to rotation to increase accuracy of the atomic gravimeter. Consequent use of these interferometers allows one to measure all components of the acceleration and rotation frequency projection on the plane perpendicular to gravity acceleration. Atom interference on the Raman transition driving by non-counterpropagating optical fields is proposed to exclude stimulated echo processes which can affect the accuracy of the atomic gyroscopes. Using non-counterpropagating optical fields allows one to get new type of the Ramsey fringes arising in the unid...

  17. Flame atomic absorption spectrometric determination of cadmium(II) and lead(II) after their solid phase extraction as dibenzyldithiocarbamate chelates on Dowex Optipore V-493

    International Nuclear Information System (INIS)

    An enrichment procedure for cadmium and lead after their solid phase extraction as dibenzyldithiocarbamate chelates on Dowex Optipore V-493 has been established prior to their flame atomic absorption spectrometric determinations. The analytical parameters including pH, amounts of dibenzyldithiocarbamate, sample volume, etc., were investigated. The effects of alkaline and earth alkaline ions and some metal ions on the retentions of analytes on Dowex Optipore V-493 resin were examined. Under the optimized conditions, the detection limits (3s, n = 21) for cadmium and lead were 0.43 μg L-1 and 0.65 μg L-1, respectively. The relative standard deviation (R.S.D.), and the recoveries of standard addition for this method were lower than 5% (n = 11) and 95-102%, respectively. Three standard reference samples (LGC 6010 Hard drinking water, NIST SRM 2711 Montana soil and GBW 07605 Tea) were introduced for accuracy and precision of analytical data. The proposed solid phase extraction system was successfully applied to the analysis of environmental samples

  18. A biosorption system for metal ions on Penicillium italicum - loaded on Sepabeads SP 70 prior to flame atomic absorption spectrometric determinations

    International Nuclear Information System (INIS)

    A solid phase extraction (SPE) preconcentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of copper(II), cadmium(II), lead(II), manganese(II), iron(III), nickel(II) and cobalt(II) ions at the μg L-1 levels on Penicillium italicum - loaded on Sepabeads SP 70. The analytes were adsorbed on biosorbent at the pH range of 8.5-9.5. The adsorbed metals were eluted with 1 mol L-1 HCl. The influences of the various analytical parameters including pH of the aqueous solutions, sample volume, flow rates were investigated for the retentions of the analyte ions. The recovery values are ranged from 95-102%. The influences of alkaline, earth alkaline and some transition metal ions were also discussed. Under the optimized conditions, the detection limits (3 s, n = 21) for analytes were in the range of 0.41 μg L-1 (cadmium) and 1.60 μg L-1 (iron). The standard reference materials (IAEA 336 Lichen, NIST SRM 1573a Tomato leaves) were analyzed to verify the proposed method. The method was successfully applied for the determinations of analytes in natural water, cultivated mushroom, lichen (Bryum capilare Hedw), moss (Homalothecium sericeum) and refined table salt samples

  19. Dolomite Dissolution in Alkaline Cementious Media

    Science.gov (United States)

    Mittermayr, Florian; Klammer, Dietmar; Köhler, Stephan; Dietzel, Martin

    2010-05-01

    Chemical alteration of concrete has gained much attention over the past years as many cases of deterioration due to sulphate attack, thaumasite formation (TSA) or alkali silica reactions (ASR) have been reported in various constructions (Schmidt et al, 2009). Much less is known about the so called alkali carbonate reaction (ACR). It is believed that dolomite aggregates can react with the alkalis from the cement, dissolve and form calcite and brucite (Katayama, 2004). Due to very low solubility of dolomite in alkaline solutions this reaction seems doubtful. In this study we are trying to gain new insides about the conditions that can lead to the dissolution of dolomite in concrete. Therefore we investigated concrete samples from Austrian tunnels that show partially dissolved dolomite aggregates. Petrological analysis such as microprobe, SEM and Raman spectroscopy as well as a hydrochemical analysis of interstitial solutions and ground water and modelling with PhreeqC (Parkhurst and Appelo, 1999) are carried out. In addition a series of batch experiments is set up. Modelling approaches by PhreeqC show a thermodynamically possibility in the alkaline range when additional Ca2+ in solution causes dolomite to become more and more undersaturated as calcite gets supersaturated. Interacting ground water is enriched in Ca2+and saturated with respect to gypsum as marine evaporites are found in situ rocks. Furthermore it is more likely that Portlandite (Ca(OH)2) plays a more important role than Na and K in the cement. Portlandite acts as an additional Ca2+ source and is much more abundant than the alkalies. Some interstitial solutions are dominated mainly by Na+ and SO42- and reach concentrations up to 30 g/l TDS. It is believed that solutions can even reach thenardite saturation as efflorescences are found on the tunnel walls. In consequence dolomite solubility increases with increasing ionic strength. pH > 11 further accelerate the process of dedolomitization by the removal

  20. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  1. Crystallographic studies on shrimp alkaline phosphatase

    NARCIS (Netherlands)

    Backer, M.M.E. (Maaike Maria Eva)

    2003-01-01

    The earth has large cold areas, such as mountains, oceans and (ant)arctic regions, in which organisms have evolved to survive. This adaptation happens at a molecular level. The question is, how do proteins adjust such that they function at low temperatures? "Cold-active" or "cold-adapted" enzymes ha

  2. Hydrogen in aluminum during alkaline corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Adhikari, Saikat; Ai, Jiahe [Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011 (United States); Hebert, Kurt R., E-mail: krhebert@iastate.ed [Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011 (United States); Ho, K.M.; Wang, C.Z. [US DOE, Ames Laboratory, Ames, IA 50011 (United States)] [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)

    2010-07-30

    The thermodynamic state of hydrogen in aluminum during alkaline corrosion was investigated, using a two-compartment hydrogen permeation cell with an Al/Pd bilayer membrane. The open-circuit potential of the Pd layer in a pH 7.0 buffer solution was monitored to sense the hydrogen chemical potential, {mu}{sub H}. At pH 12.5-13.5, the measurements established a minimum {mu}{sub H} of 0.55 eV relative to the ideal gas reference, equivalent to a H{sub 2} gas pressure of 5.7 GPa. Statistical mechanics calculations show that vacancy-hydrogen defects are stable in Al at this condition. A dissolution mechanism was proposed in which H at very high {mu}{sub H} is produced by oxidation of interfacial aluminum hydride. The mechanism explains the observed rapid accumulation of H in the metal by extensive formation of vacancy-hydrogen defects.

  3. Alkaline lixiviation of uranium in granitic pegmatite

    International Nuclear Information System (INIS)

    The work described herein concerns the determination of the experimental optimum conditions for the alkaline lixiviation of uranium based on the following parameters: time, pH, temperature, density and grane size. The samples were obtained from the Supamo complex, near the Currupia river in the Piar District of the Bolivar State in Venezuela. They have a granitic composition and graphitic texture. The uranium was found in them as a secondary oxidized mineral of green-yellow colour localized in fractures fissures, intergranular spaces and also in the mica as. Secondary uranitite. The lixiviation process was carried out using Na2CO3/NaHCO3 buffer solution and for 100 gr. samples the best values for an efficient process were found by using 170 mesh grane size and 500 ml of pH buffer at 700C for a 24 hour time period. (author)

  4. Alkaline oxide conversion coatings for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, R.G.

    1996-02-01

    Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. Representative examples of the processing methods, resulting coating structure, composition and morphology are presented. The corrosion resistance of these coatings to aerated 0.5 M NaCl solution has been evaluated as a function of total processing time using electrochemical impedance spectroscopy (EIS). This evaluation shows that excellent corrosion resistance can be uniformly achieved using no more than 20 minutes of process time for 6061-T6. Using current methods a minimum of 80 minutes of process time is required to get marginally acceptable corrosion resistance for 2024-T3. Longer processing times are required to achieve uniformly good corrosion resistance.

  5. Alkaline pulping of some eucalypts from Sudan.

    Science.gov (United States)

    Khristova, P; Kordsachia, O; Patt, R; Dafaalla, S

    2006-03-01

    Four eucalypts (Eucalyptus camaldulensis, Eucalyptus microtheca, Eucalyptus tereticornis and Eucalyptus citriodora) grown in Sudan were examined for their suitability for pulping and papermaking with different alkaline methods. Their physical, morphological and chemical characteristics are reported. The pulping trials with E. citriodora and E. tereticornis were carried out using the kraft-AQ, soda-AQ, modified AS/AQ (ASA), ASAM and kraft methods. For the other two species, only the ASAM and the kraft process were applied. ASAM pulping gave the best results in terms of yield, degree of delignification, mechanical and optical pulp properties. The best pulps, obtained in kraft and ASAM cooking of E. citriodora, were bleached to 88% ISO brightness in a totally chlorine free bleaching sequence (OQ1O/PQ2P). The bleached pulps, especially the ASAM pulp, showed good papermaking properties and would be suitable for manufacture of writing and printing grades of paper. PMID:15935655

  6. Large momentum transfer atom interferometry with Coriolis force compensation

    Science.gov (United States)

    Kuan, Pei-Chen; Lan, Shau-Yu; Estey, Brian; Haslinger, Philipp; Mueller, Holger

    2012-06-01

    Light-pulse atom interferometers use atom-photon interactions to coherently split, guide, and recombine freely falling matter-waves. Because of Earth's rotation, however, the matter-waves do not recombine precisely, which causes severe loss of contrast in large space-time atom interferometers. I will present our recent progress in using a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation. Therefore, we improve the contrast and suppress systematic effects, also reach what is to our knowledge the largest spacetime area.

  7. Solubility of some alkali and alkaline earth chlorides in water at moderate temperatures

    Science.gov (United States)

    Clynne, M.A.; Potter, R.W.

    1979-01-01

    Solubilities for the binary systems, salt-H2O, of the chlorides of lithium, rubidium, cesium, magnesium, calcium, strontium, and barium from near 0??C to the saturated boiling point are reported. The experimental data and coefficients of an equation for a smoothed curve describing each system are listed in the tables. The data are improvements on those previously reported in the literature, having a precision on the average of ??0.09%.

  8. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses.

    Science.gov (United States)

    Kansal, Ishu; Reddy, AlluAmarnath; Muñoz, Francisco; Choi, Seong-Jun; Kim, Hae-Won; Tulyaganov, Dilshat U; Ferreira, José M F

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO-MgO-SiO2-P2O5-CaF2 system. The (29)Si and (31)P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na2O/MgO ratios exhibit a silicate glass network with the dominance of Q(2)(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1h and 7 days while their chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Increasing Na(+)/Mg(2+) ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. PMID:25280692

  9. Alkaline-earth oxide network modifier on optical properties of Ce3+-activated borogermanate glasses

    Science.gov (United States)

    Sun, Xin-Yuan; Xiao, Zhuo-Hao; Zhong, Jiu-Ping

    2015-12-01

    Transparent and colorless CeO2-activated borogermanate glasses, with the nominal composition of 25B2O3-40GeO2-14Gd2O3-1CeO2-20MO (M = Ba, Sr, Ca and Mg), were synthesized by a melt-quenching method in air. Their optical properties including the transmittance, photoluminescence (excitation and emission spectra), the luminescence decay curves, as well as the temperature-dependent emission spectra were studied in detail. The room temperature photoluminescence spectra reveal that the emission intensity of the MgO glass is about two times stronger than that of the BaO glass. The blue shift of the cut-off edge, excitation and emission spectra of Ce3+-activated borogermanate glass were clearly observed in the order of BaO, SrO, CaO and MgO. And the emission intensity of Ce3+ ions as a function of temperature range in 325-475 K was also investigated.

  10. Adsorption of alkali and alkaline earth radionuclides on zeolite from water solutions

    International Nuclear Information System (INIS)

    The adsorption of cesium and strontium ions from water solutions on zeolite has been investigated in presence of sodium, potassium, magnesium and calcium ions. Distribution ratios of cesium and strontium on the zeolite were determined in solutions of various compositions and solution volume to sorbent weight ratios (batch factor). Breakthrough curves for zeolite layers are reported. (author) 7 refs.; 4 figs

  11. Synthesis and properties of mixed alkali-metal–alkaline-earth fullerides

    NARCIS (Netherlands)

    Barbedette, L.; Fischer, J.E.; Bendele, G.M.; Stephens, P.W.; Lin, C.L.; Goze, C.; Rachdi, F.; Robert, J.; Petit, P.; Palstra, T.T.M.

    1996-01-01

    A new class of fullerides, MBa2C60 (M=K, Rb, or Cs) and MBaCsC60, allows us to study the effect of molecular valence on electronic structure while maintaining the crystal structure of M3C60 superconductors. X-ray diffraction and Raman scattering show that these are face-centered cubic with pentavale

  12. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kansal, Ishu; Reddy, AlluAmarnath [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Muñoz, Francisco [Ceramics and Glass Institute (CSIC), Kelsen 5, 28049 Madrid (Spain); Choi, Seong-Jun [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Kim, Hae-Won [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330714 (Korea, Republic of); Tulyaganov, Dilshat U. [Turin Polytechnic University in Tashkent, 100095 Tashkent (Uzbekistan); Ferreira, José M.F., E-mail: jmf@ua.pt [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO–MgO–SiO{sub 2}–P{sub 2}O{sub 5}–CaF{sub 2} system. The {sup 29}Si and {sup 31}P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na{sub 2}O/MgO ratios exhibit a silicate glass network with the dominance of Q{sup 2}(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na{sup +}/Mg{sup 2+} ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. - Highlights: • Na{sup +} did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na{sup +}/Mg{sup 2+} ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium.

  13. Negative ions in vapors of alkaline earth metal dichlorides. Enthalpy of ion formation

    International Nuclear Information System (INIS)

    Results of investigation into the negative component of Sr and Ba dichloride saturated vapors are presented. Investigations were conducted using ion-molecular equilibrium method which is one of the options of mass-spectrometry method. Cl-, SrCl3-, Sr2Cl5- ions are identified above SrCl2 within 1000-1300 K temperature interval. Based on obtained experimental values and literary data SrCl3- and Sr2Cl5- gaseous ion formation enthalpies, making up respectively -1008±15 and -1769±30 kJ/mol, at 0 K are calculated. 25 refs.; 1 fig.; 4 tabs

  14. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses

    International Nuclear Information System (INIS)

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO–MgO–SiO2–P2O5–CaF2 system. The 29Si and 31P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na2O/MgO ratios exhibit a silicate glass network with the dominance of Q2(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na+/Mg2+ ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. - Highlights: • Na+ did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na+/Mg2+ ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium

  15. Study the influence of zinc oxide addition on cobalt doped alkaline earth borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, F., E-mail: F.Ahmad378@yahoo.com [Department of Physics, Faculty of Science, Alazhar University (Girls Branch), Nasr City, Cairo (Egypt); Hassan Aly, E. [Department of Physics, Faculty of Science, Ain Shams University, P.O. Box 11566, Abbassia, Cairo (Egypt); Atef, M.; ElOkr, M.M. [Department of Physics, Faculty of Science, Alazhar University, Nasr City, Cairo (Egypt)

    2014-04-01

    Highlights: • The glassy system xZnO–(79.9−x)B{sub 2}O{sub 3}–20BaO–0.1Co{sub 3}O{sub 4} was prepared by a quenching method. • XRD patterns revealed that the amorphous nature of the present glasses matrix. • The results show that Zn{sup 2+} ions occupy both forming and modifying positions. • Optical parameters are reported as a function of ZnO content. - Abstract: The glasses of the composition 79.9B{sub 2}O{sub 3}–20BaO–0.1Co{sub 3}O{sub 4} doped with different concentrations of ZnO (5, 10, 15, 20, 25 and 30 mol%) were prepared using melt quenching technique. Various studies such as XRD, density, theoretical optical basicity, FT-IR and optical absorption have been carried out to study the role of ZnO on the physical and structural properties of the investigated system. Powder X-ray diffraction patterns confirmed the glassy nature of all the glassy samples. The density and molar volume of glassy samples showed opposite behavior to each other. An increment of the theoretical optical basicity with increasing ZnO content, which is due to an increase in the polarizability and a decrease in the single bond strength is observed. FT-IR analysis revealed that an increase in non-bridging oxygen’s (NBO’s) up to ZnO ⩽ 15 mol% and then a decrease at ZnO > 15 mol%. The results indicated that the Zn{sup 2+} ions are likely to occupy network modifier positions at a concentration of ZnO ⩽ 15 mol%. Above which these ions occupy network forming positions. From ultraviolet absorption edges calculations, the optical band gap energy and steepness parameter decrease whilst Urbach energy and refractive index increase by the addition of ZnO up to 15 mol% above which then the behavior follows reversal trend. The values of the crystal field strength and the interelectronic repulsion Racah parameter calculated from the optical transitions energies of cobalt doped glassy samples. All prepared samples exhibit blue color, indicating that mostly Co ions are acted upon by tetrahedral ligand field.

  16. Study the influence of zinc oxide addition on cobalt doped alkaline earth borate glasses

    International Nuclear Information System (INIS)

    Highlights: • The glassy system xZnO–(79.9−x)B2O3–20BaO–0.1Co3O4 was prepared by a quenching method. • XRD patterns revealed that the amorphous nature of the present glasses matrix. • The results show that Zn2+ ions occupy both forming and modifying positions. • Optical parameters are reported as a function of ZnO content. - Abstract: The glasses of the composition 79.9B2O3–20BaO–0.1Co3O4 doped with different concentrations of ZnO (5, 10, 15, 20, 25 and 30 mol%) were prepared using melt quenching technique. Various studies such as XRD, density, theoretical optical basicity, FT-IR and optical absorption have been carried out to study the role of ZnO on the physical and structural properties of the investigated system. Powder X-ray diffraction patterns confirmed the glassy nature of all the glassy samples. The density and molar volume of glassy samples showed opposite behavior to each other. An increment of the theoretical optical basicity with increasing ZnO content, which is due to an increase in the polarizability and a decrease in the single bond strength is observed. FT-IR analysis revealed that an increase in non-bridging oxygen’s (NBO’s) up to ZnO ⩽ 15 mol% and then a decrease at ZnO > 15 mol%. The results indicated that the Zn2+ ions are likely to occupy network modifier positions at a concentration of ZnO ⩽ 15 mol%. Above which these ions occupy network forming positions. From ultraviolet absorption edges calculations, the optical band gap energy and steepness parameter decrease whilst Urbach energy and refractive index increase by the addition of ZnO up to 15 mol% above which then the behavior follows reversal trend. The values of the crystal field strength and the interelectronic repulsion Racah parameter calculated from the optical transitions energies of cobalt doped glassy samples. All prepared samples exhibit blue color, indicating that mostly Co ions are acted upon by tetrahedral ligand field

  17. EPR and optical absorption studies of VO2+ ions in alkaline earth aluminoborate glasses

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR) and optical absorption studies have been carried out for VO2+ ions in calcium aluminoborate glasses. The EPR spectra of all the glass samples exhibit resonance signals, characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in calcium aluminoborate glasses were present in octahedral co-ordination with a tetragonal compression and belong to C4v symmetry. The number of spins (N) participating in resonance was calculated as a function of concentration as well as temperature. It is observed that variation of N with temperature obeys the Boltzmann law. From the EPR data, the paramagnetic susceptibility (χ) is calculated at various temperatures and the Curie constant (C) was evaluated from the 1/χ-T graph. The Fermi contact interaction parameter (k), dipolar hyperfine coupling parameter (P) have been calculated and these values are found to be independent of V2O5 content and temperature. The optical absorption spectrum exhibits two bands corresponding to the d-d transition 2B2g → 2Eg and 2B2g → 2A1g in the order of increasing energy. The theoretical values of optical basicity (Λth) of the glasses have also been evaluated

  18. Chemical perspectives on alkali and earth alkaline nitrate and nitrite salts for concentrated solar power applications

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph G. [Sandia National Labsoratories, Livermore, CA (United States)

    2013-04-01

    Molten salts have been widely considered as the leading candidate heat transfer fluids (HTF) used in high temperature, concentrated solar power plants. Specifically, nitrate and nitrite based salts have been investigated as a HTF and even deployed in pilot plants generating up to 19.9 MW of electricity at operating temperatures above 500 C. New plant designs requiring higher operating temperatures for better efficiencies are pushing the stability limit of HTF. This paper presents an overview of the thermophysical properties of nitrate and nitrite salts and discusses thermodynamic and kinetic stability limitations as they relate to concentrated solar power generation. (orig.)

  19. Enzymatic Hydrolysis of Alkaline Pretreated Coconut Coir

    Directory of Open Access Journals (Sweden)

    Akbarningrum Fatmawati

    2013-06-01

    Full Text Available The purpose of this research is to study the effect of concentration and temperature on the cellulose and lignin content, and the reducing sugars produced in the enzymatic hydrolysis of coconut coir. In this research, the coconut coir is pretreated using 3%, 7%, and 11% NaOH solution at 60oC, 80oC, and 100oC. The pretreated coir were assayed by measuring the amount of cellulose and lignin and then hydrolysed using Celluclast and Novozyme 188 under various temperature (30oC, 40oC, 50oC and pH (3, 4, 5. The hydrolysis results were assayed for the reducing sugar content. The results showed that the alkaline delignification was effective to reduce lignin and to increase the cellulose content of the coir. The best delignification condition was observed at 11% NaOH solution and 100oC which removed 14,53% of lignin and increased the cellulose content up to 50,23%. The best condition of the enzymatic hydrolysis was obtained at 50oC and pH 4 which produced 7,57 gr/L reducing sugar. © 2013 BCREC UNDIP. All rights reservedReceived: 2nd October 2012; Revised: 31st January 2013; Accepted: 6th February 2013[How to Cite: Fatmawati, A., Agustriyanto, R., Liasari, Y. (2013. Enzymatic Hydrolysis of Alkaline Pre-treated Coconut Coir. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 34-39 (doi:10.9767/bcrec.8.1.4048.34-39[Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4048.34-39] | View in  |

  20. Atomic Energy Basics, Understanding the Atom Series.

    Science.gov (United States)

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  1. Nucleotide and amino acid sequences of human intestinal alkaline phosphatase: close homology to placental alkaline phosphatase

    International Nuclear Information System (INIS)

    A cDNA clone for human adult intestinal alkaline phosphatase (ALP) [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1] was isolated from a λgt11 expression library. The cDNA insert of this clone is 2513 base pairs in length and contains an open reading frame that encodes a 528-amino acid polypeptide. This deduced polypeptide contains the first 40 amino acids of human intestinal ALP, as determined by direct protein sequencing. Intestinal ALP shows 86.5% amino acid identity to placental (type 1) ALP and 56.6% amino acid identity to liver/bone/kidney ALP. In the 3'-untranslated regions, intestinal and placental ALP cDNAs are 73.5% identical (excluding gaps). The evolution of this multigene enzyme family is discussed

  2. Space-time variability of alkalinity in the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    G. Cossarini

    2014-09-01

    Full Text Available The paper provides a basin assessment of the spatial distribution of ocean alkalinity in the Mediterranean Sea. The assessment is made using a 3-D transport-biogeochemical-carbonate model to integrate the available experimental findings, which also constrains model output. The results indicate that the Mediterranean Sea shows alkalinity values that are much higher than those observed in the Atlantic Ocean on a basin-wide scale. A marked west-to-east surface gradient of alkalinity is reproduced as a response to the terrestrial discharges, the mixing effect with the Atlantic water entering from the Gibraltar Strait and the Black Sea water from Dardanelles, and the surface flux of evaporation minus precipitation. Dense water production in marginal seas (Adriatic and Aegean Seas, where alkaline inputs are relevant, and the Mediterranean thermohaline circulation sustains the west-to-east gradient along the entire water column. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1 that is driven both by physical and biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships. In regions of freshwater influence, the two measures are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open seas. Alkalinity always is much higher than in the Atlantic waters, which might indicate a higher than usual buffering capacity towards ocean acidification, even at high concentrations of dissolved inorganic carbon.

  3. Increased river alkalinization in the Eastern U.S.

    Science.gov (United States)

    Kaushal, Sujay S; Likens, Gene E; Utz, Ryan M; Pace, Michael L; Grese, Melissa; Yepsen, Metthea

    2013-09-17

    The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km(2). We observed statistically significant increasing trends in alkalinity at 62 of the 97 sites, while remaining sites exhibited no significant decreasing trends. Over 50% of study sites also had statistically significant increasing trends in concentrations of calcium (another product of chemical weathering) where data were available. River alkalinization rates were significantly related to watershed carbonate lithology, acid deposition, and topography. These three variables explained ~40% of variation in river alkalinization rates. The strongest predictor of river alkalinization rates was carbonate lithology. The most rapid rates of river alkalinization occurred at sites with highest inputs of acid deposition and highest elevation. The rise of alkalinity in many rivers throughout the Eastern U.S. suggests human-accelerated chemical weathering, in addition to previously documented impacts of mining and land use. Increased river alkalinization has major environmental implications including impacts on water hardness and salinization of drinking water, alterations of air-water exchange of CO2, coastal ocean acidification, and the influence of bicarbonate availability on primary production.

  4. Digital Earth – A sustainable Earth

    International Nuclear Information System (INIS)

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth

  5. Teach us atom structure

    International Nuclear Information System (INIS)

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  6. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  7. Atomic phase diagram

    Institute of Scientific and Technical Information of China (English)

    LI Shichun

    2004-01-01

    Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.

  8. Phosphatidylinositol anchor of HeLa cell alkaline phosphatase

    International Nuclear Information System (INIS)

    Alkaline phosphatase from cancer cells, HeLa TCRC-1, was biosynthetically labeled with either 3H-fatty acids or [3H]ethanolamine as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material. Phosphatidylinositol-specific phospholipase C (PI-PLC) released a substantial proportion of the 3H-fatty acid label from immunoaffinity-purified alkaline phosphatase but had no effect on the radioactivity of [3H]ethanolamine-labeled material. PI-PLC also liberated catalytically active alkaline phosphatase from viable cells, and this could be selectively blocked by monoclonal antibodies to alkaline phosphatase. However, the alkaline phosphatase released from 3H-fatty acid labeled cells by PI-PLC was not radioactive. By contrast, treatment with bromelain removed both the 3H-fatty acid and the [3H]ethanolamine label from purified alkaline phosphatase. Subtilisin was also able to remove the [3H]ethanolamine label from the purified alkaline phosphatase. The 3H radioactivity in alkaline phosphatase purified from [3H]ethanolamine-labeled cells comigrated with authentic [3H]ethanolamine by anion-exchange chromatography after acid hydrolysis. The data suggest that the 3H-fatty acid and [3H]ethanolamine are covalently attached to the carboxyl-terminal segment since bromelain and subtilisin both release alkaline phosphatase from the membrane by cleavage at that end of the polypeptide chain. The data are consistent with findings for other proteins recently shown to be anchored in the membrane through a glycosylphosphatidylinositol structure and indicate that a similar structure contributes to the membrane anchoring of alkaline phosphatase

  9. Phosphatidylinositol anchor of HeLa cell alkaline phosphatase

    Energy Technology Data Exchange (ETDEWEB)

    Jemmerson, R.; Low, M.G.

    1987-09-08

    Alkaline phosphatase from cancer cells, HeLa TCRC-1, was biosynthetically labeled with either /sup 3/H-fatty acids or (/sup 3/H)ethanolamine as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material. Phosphatidylinositol-specific phospholipase C (PI-PLC) released a substantial proportion of the /sup 3/H-fatty acid label from immunoaffinity-purified alkaline phosphatase but had no effect on the radioactivity of (/sup 3/H)ethanolamine-labeled material. PI-PLC also liberated catalytically active alkaline phosphatase from viable cells, and this could be selectively blocked by monoclonal antibodies to alkaline phosphatase. However, the alkaline phosphatase released from /sup 3/H-fatty acid labeled cells by PI-PLC was not radioactive. By contrast, treatment with bromelain removed both the /sup 3/H-fatty acid and the (/sup 3/H)ethanolamine label from purified alkaline phosphatase. Subtilisin was also able to remove the (/sup 3/H)ethanolamine label from the purified alkaline phosphatase. The /sup 3/H radioactivity in alkaline phosphatase purified from (/sup 3/H)ethanolamine-labeled cells comigrated with authentic (/sup 3/H)ethanolamine by anion-exchange chromatography after acid hydrolysis. The data suggest that the /sup 3/H-fatty acid and (/sup 3/H)ethanolamine are covalently attached to the carboxyl-terminal segment since bromelain and subtilisin both release alkaline phosphatase from the membrane by cleavage at that end of the polypeptide chain. The data are consistent with findings for other proteins recently shown to be anchored in the membrane through a glycosylphosphatidylinositol structure and indicate that a similar structure contributes to the membrane anchoring of alkaline phosphatase.

  10. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    The word planet comes from Greek planetes, wanderers, because the planets appear to wander across the celestial sphere, contrary to the fixed stars. This thesis presents several methods for using this motion to distinguish between stars and solar system objects in order to detect and track NEOs......, Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...

  11. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  12. Cold Matter Assembled Atom-by-Atom

    CERN Document Server

    Endres, Manuel; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D

    2016-01-01

    The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.

  13. The effect of irrigated rice cropping on the alkalinity of two alkaline rice soils in the Sahel

    NARCIS (Netherlands)

    Asten, van P.J.A.; Zelfde, van 't J.A.; Zee, van der S.E.A.T.M.; Hammecker, C.

    2004-01-01

    Irrigated rice cropping is practiced to reclaim alkaline-sodic soils in many parts of the world. This practice is in apparent contrast with earlier studies in the Sahel, which suggests that irrigated rice cropping may lead to the formation of alkaline-sodic soils. Soil column experiments were done w

  14. Atomic collisions under extreme conditions in space

    International Nuclear Information System (INIS)

    In space, atoms and molecules are often placed under the extreme conditions which are very difficult to be realized on Earth. For instance, extremely hot and dense plasmas are found in and around various stellar objects (e.g., neutron stars) on one hand and extremely cold and diffuse gases prevail in interstellar space on the other. There is so strong a magnetic field that electron clouds in atoms and molecules are distorted. The study of atomic collisions under the extreme conditions is not only helpful in understanding the astrophysical environment but also reveals new aspects of the physics of atoms and molecules. This paper is an invitation to the study. (References are not exhaustive but only provide a clue with which more details can be found.) (author)

  15. Microbial thiocyanate utilization under highly alkaline conditions.

    Science.gov (United States)

    Sorokin, D Y; Tourova, T P; Lysenko, A M; Kuenen, J G

    2001-02-01

    Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS-) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase

  16. Charge-order driven multiferroic and magneto-dielectric properties of rare earth manganates

    Indian Academy of Sciences (India)

    Claudy Rayan Serrao; Jyoti Ranjan Sahu; Anirban Ghosh

    2010-04-01

    Charge-order driven magnetic ferroelectricity is shown to occur in several rare earth manganates of the general formula, Ln1–AMnO3 (Ln = rare earth, A = alkaline earth). Charge-ordered manganates exhibit dielectric constant anomalies around the charge-ordering or the antiferromagnetic transition temperature. Magnetic fields have a marked effect on the dielectric properties of these compounds, indicating the presence of coupling between the magnetic and electrical order parameters. Magneto-dielectric properties are retained in small particles of the manganates. The observation of magneto-ferroelectricity in these manganates is in accordance with theoretical predictions.

  17. The Earth Charter

    Science.gov (United States)

    Journal of Education for Sustainable Development, 2010

    2010-01-01

    Humanity is part of a vast evolving universe. Earth is alive with a unique community of life. The forces of nature make existence a demanding and uncertain adventure, but Earth has provided the conditions essential to life's evolution. The resilience of the community of life and the well-being of humanity depend upon preserving a healthy biosphere…

  18. Earth System Science Project

    Science.gov (United States)

    Rutherford, Sandra; Coffman, Margaret

    2004-01-01

    For several decades, science teachers have used bottles for classroom projects designed to teach students about biology. Bottle projects do not have to just focus on biology, however. These projects can also be used to engage students in Earth science topics. This article describes the Earth System Science Project, which was adapted and developed…

  19. Titratable Acidity and Alkalinity of Red Soil Surfaces

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1993-01-01

    The surfaces of red soils have an apparent amphoteric character,carrying titratable acidity and titratable alkalinity simultaneously.The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter,while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces.The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils.The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution,free iron oxide(Fed) extracted with sodium dithionite-citrate-bicarbonate(DCB) and clays,but also with the zero point of charge (ZPC) of the samples.Organic matter made an important contribution to the titratable acidity.the titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed.The titratable acidity and titratable alkalinity of red soils were influenced by parent materials,being in the order of red soil derived from basalt> that from tuff> that from granite.The titratable acidity and titratable alkalinity ware closely related with origination of the variable charges of red soils,and to a certain extent were responsible for variable negative and positive charges of the soils.

  20. Francisella DnaK Inhibits Tissue-nonspecific Alkaline Phosphatase*

    Science.gov (United States)

    Arulanandam, Bernard P.; Chetty, Senthilnath Lakshmana; Yu, Jieh-Juen; Leonard, Sean; Klose, Karl; Seshu, Janakiram; Cap, Andrew; Valdes, James J.; Chambers, James P.

    2012-01-01

    Following pulmonary infection with Francisella tularensis, we observed an unexpected but significant reduction of alkaline phosphatase, an enzyme normally up-regulated following inflammation. However, no reduction was observed in mice infected with a closely related Gram-negative pneumonic organism (Klebsiella pneumoniae) suggesting the inhibition may be Francisella-specific. In similar fashion to in vivo observations, addition of Francisella lysate to exogenous alkaline phosphatase (tissue-nonspecific isozyme) was inhibitory. Partial purification and subsequent proteomic analysis indicated the inhibitory factor to be the heat shock protein DnaK. Incubation with increasing amounts of anti-DnaK antibody reduced the inhibitory effect in a dose-dependent manner. Furthermore, DnaK contains an adenosine triphosphate binding domain at its N terminus, and addition of adenosine triphosphate enhances dissociation of DnaK with its target protein, e.g. alkaline phosphatase. Addition of adenosine triphosphate resulted in decreased DnaK co-immunoprecipitated with alkaline phosphatase as well as reduction of Francisella-mediated alkaline phosphatase inhibition further supporting the binding of Francisella DnaK to alkaline phosphatase. Release of DnaK via secretion and/or bacterial cell lysis into the extracellular milieu and inhibition of plasma alkaline phosphatase could promote an orchestrated, inflammatory response advantageous to Francisella. PMID:22923614