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Sample records for 2h2o sintez struktura

  1. Liquid water on Mars - An energy balance climate model for CO2/H2O atmospheres

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.; Callegari, A. J.; Hsieh, C. T.; Ziegler, W.

    1981-01-01

    A simple climatic model is developed for a Mars atmosphere containing CO2 and sufficient liquid water to account for the observed hydrologic surface features by the existence of a CO2/H2O greenhouse effect. A latitude-resolved climate model originally devised for terrestrial climate studies is applied to Martian conditions, with the difference between absorbed solar flux and emitted long-wave flux to space per unit area attributed to the divergence of the meridional heat flux and the poleward heat flux assumed to equal the atmospheric eddy heat flux. The global mean energy balance is calculated as a function of atmospheric pressure to assess the CO2/H2O greenhouse liquid water hypothesis, and some latitude-resolved cases are examined in detail in order to clarify the role of atmospheric transport and temperature-albedo feedback. It is shown that the combined CO2/H2O greenhouse at plausible early surface pressures may account for climates hot enough to support a hydrological cycle and running water at present-day insolation and visible albedo levels.

  2. Mid-Infrared Spectrum of the Atmospherically Significant N2-H2O Complex

    NASA Astrophysics Data System (ADS)

    Springer, Sean D.; McElmurry, Blake A.; Lucchese, Robert R.; Bevan, John W.; Coudert, L. H.

    2014-06-01

    Rovibrational transitions associated with tunneling states in the vibration of the N2-H2O complex have been recorded using a supersonic jet quantum cascade laser spectrometer at 6.2μm. Analysis of the resulting spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data accounting for Coriolis coupling to obtain the levels of the ground vibrational state. The results are then used to confirm assignment of the νb{3} vibration and explore the nature of tunneling dynamics in associated vibrationally excited states of the complex.

  3. Redetermination of [EuCl2(H2O)6]Cl

    PubMed Central

    Tambornino, Frank; Bielec, Philipp; Hoch, Constantin

    2014-01-01

    The crystal structure of the title compound, hexa­aqua­dichlorido­europium(III) chloride, was redetermined with modern crystallographic methods. In comparison with the previous study [Lepert et al. (1983 ▶). Aust. J. Chem. 36, 477–482], it could be shown that the atomic coordinates of some O atoms had been confused and now were corrected. Moreover, it was possible to freely refine the positions of the H atoms and thus to improve the accurracy of the crystal structure. [EuCl2(H2O)6]Cl crystallizes with the GdCl3·6H2O structure-type, exhibiting discrete [EuCl2(H2O)6]+ cations as the main building blocks. The main blocks are linked with isolated chloride anions via O—H⋯Cl hydrogen bonds into a three-dimensional framework. The Eu3+ cation is located on a twofold rotation axis and is coordinated in the form of a Cl2O6 square anti­prism. One chloride anion coordinates directly to Eu3+, whereas the other chloride anion, situated on a twofold rotation axis, is hydrogen bonded to six octa­hedrally arranged water mol­ecules. PMID:24940187

  4. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    PubMed

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra. PMID:25621533

  5. Volumetric Properties and Fluid Phase Equilibria of CO2 + H2O

    SciTech Connect

    Capobianco, Ryan; Gruszkiewicz, Miroslaw {Mirek} S; Wesolowski, David J; Cole, David R; Bodnar, Robert

    2013-01-01

    The need for accurate modeling of fluid-mineral processes over wide ranges of temperature, pressure and composition highlighted considerable uncertainties of available property data and equations of state, even for the CO2 + H2O binary system. In particular, the solubility, activity, and ionic dissociation equilibrium data for the CO2-rich phase, which are essential for understanding dissolution/precipitation, fluid-matrix reactions, and solute transport, are uncertain or missing. In this paper we report the results of a new experimental study of volumetric and phase equilibrium properties of CO2 + H2O, to be followed by measurements for bulk and confined multicomponent fluid mixtures. Mixture densities were measured by vibrating tube densimetry (VTD) over the entire composition range at T = 200 and 250 C and P = 20, 40, 60, and 80 MPa. Initial analysis of the mutual solubilities, determined from volumetric data, shows good agreement with earlier results for the aqueous phase, but finds that the data of Takenouchi and Kennedy (1964) significantly overestimated the solubility of water in supercritical CO2 (by a factor of more than two at 200 C). Resolving this well-known discrepancy will have a direct impact on the accuracy of predictive modeling of CO2 injection in geothermal reservoirs and geological carbon sequestration through improved equations of state, needed for calibration of predictive molecular-scale models and large-scale reactive transport simulations.

  6. Optimization of intermolecular potential parameters for the CO2/H2O mixture.

    PubMed

    Orozco, Gustavo A; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2014-10-01

    Monte Carlo simulations in the Gibbs ensemble were used to obtain optimized intermolecular potential parameters to describe the phase behavior of the mixture CO2/H2O, over a range of temperatures and pressures relevant for carbon capture and sequestration processes. Commonly used fixed-point-charge force fields that include Lennard-Jones 12-6 (LJ) or exponential-6 (Exp-6) terms were used to describe CO2 and H2O intermolecular interactions. For force fields based on the LJ functional form, changes of the unlike interactions produced higher variations in the H2O-rich phase than in the CO2-rich phase. A major finding of the present study is that for these potentials, no combination of unlike interaction parameters is able to adequately represent properties of both phases. Changes to the partial charges of H2O were found to produce significant variations in both phases and are able to fit experimental data in both phases, at the cost of inaccuracies for the pure H2O properties. By contrast, for the Exp-6 case, optimization of a single parameter, the oxygen-oxygen unlike-pair interaction, was found sufficient to give accurate predictions of the solubilities in both phases while preserving accuracy in the pure component properties. These models are thus recommended for future molecular simulation studies of CO2/H2O mixtures. PMID:25198539

  7. Exploring water binding motifs to an excess electron via X2(-)(H2O) [X = O, F].

    PubMed

    Chiou, Mong-Feng; Sheu, Wen-Shyan

    2012-07-26

    X(2)(-)(H(2)O) [X = O, F] is utilized to explore water binding motifs to an excess electron via ab initio calculations at the MP4(SDQ)/aug-cc-pVDZ + diffs(2s2p,2s2p) level of theory. X(2)(-)(H(2)O) can be regarded as a water molecule that binds to an excess electron, the distribution of which is gauged by X(2). By varying the interatomic distance of X(2), r(X1-X2), the distribution of the excess electron is altered, and the water binding motifs to the excess electron is then examined. Depending on r(X1-X2), both binding motifs of C(s) and C(2v) forms are found with a critical distance of ∼1.37 Å and ∼1.71 Å for O(2)(-)(H(2)O) and F(2)(-)(H(2)O), respectively. The energetic and geometrical features of O(2)(-)(H(2)O) and F(2)(-)(H(2)O) are compared. In addition, various electronic properties of X(2)(-)(H(2)O) are examined. For both O(2)(-)(H(2)O) and F(2)(-)(H(2)O), the C(s) binding motif appears to prevail at a compact distribution of the excess electron. However, when the electron is diffuse, characterized by the radius of gyration in the direction of the X(2) bond axis with a threshold of ∼0.84 Å, the C(2v) binding motif is formed. PMID:22762788

  8. Full-dimensional, high-level ab initio potential energy surfaces for H2(H2O) and H2(H2O)2 with application to hydrogen clathrate hydrates

    NASA Astrophysics Data System (ADS)

    Homayoon, Zahra; Conte, Riccardo; Qu, Chen; Bowman, Joel M.

    2015-08-01

    New, full-dimensional potential energy surfaces (PESs), obtained using precise least-squares fitting of high-level electronic energy databases, are reported for intrinsic H2(H2O) two-body and H2(H2O)2 three-body potentials. The database for H2(H2O) consists of approximately 44 000 energies at the coupled cluster singles and doubles plus perturbative triples (CCSD(T))-F12a/haQZ (aug-cc-pVQZ for O and cc-pVQZ for H) level of theory, while the database for the three-body interaction consists of more than 36 000 energies at the CCSD(T)-F12a/haTZ (aug-cc-pVTZ for O, cc-pVTZ for H) level of theory. Two precise potentials are based on the invariant-polynomial technique and are compared to computationally faster ones obtained via "purified" symmetrization. All fits use reduced permutational symmetry appropriate for these non-covalent interactions. These intrinsic potentials are employed together with existing ones for H2, H2O, and (H2O)2, to obtain full PESs for H2(H2O) and H2(H2O)2. Properties of these full PESs are presented, including a diffusion Monte Carlo calculation of the zero-point energy and wavefunction, and dissociation energy of the H2(H2O) dimer. These PESs together with an existing one for water clusters are used in a many-body representation of the PES of hydrogen clathrate hydrates, illustrated for H2@(H2O)20. An analysis of this hydrate is presented, including the electronic dissociation energy to remove H2 from the calculated equilibrium structure.

  9. Full-dimensional, high-level ab initio potential energy surfaces for H2(H2O) and H2(H2O)2 with application to hydrogen clathrate hydrates.

    PubMed

    Homayoon, Zahra; Conte, Riccardo; Qu, Chen; Bowman, Joel M

    2015-08-28

    New, full-dimensional potential energy surfaces (PESs), obtained using precise least-squares fitting of high-level electronic energy databases, are reported for intrinsic H2(H2O) two-body and H2(H2O)2 three-body potentials. The database for H2(H2O) consists of approximately 44 000 energies at the coupled cluster singles and doubles plus perturbative triples (CCSD(T))-F12a/haQZ (aug-cc-pVQZ for O and cc-pVQZ for H) level of theory, while the database for the three-body interaction consists of more than 36 000 energies at the CCSD(T)-F12a/haTZ (aug-cc-pVTZ for O, cc-pVTZ for H) level of theory. Two precise potentials are based on the invariant-polynomial technique and are compared to computationally faster ones obtained via "purified" symmetrization. All fits use reduced permutational symmetry appropriate for these non-covalent interactions. These intrinsic potentials are employed together with existing ones for H2, H2O, and (H2O)2, to obtain full PESs for H2(H2O) and H2(H2O)2. Properties of these full PESs are presented, including a diffusion Monte Carlo calculation of the zero-point energy and wavefunction, and dissociation energy of the H2(H2O) dimer. These PESs together with an existing one for water clusters are used in a many-body representation of the PES of hydrogen clathrate hydrates, illustrated for H2@(H2O)20. An analysis of this hydrate is presented, including the electronic dissociation energy to remove H2 from the calculated equilibrium structure. PMID:26328838

  10. Modeling Ice Giant Interiors Using Constraints on the H2-H2O Critical Curve

    NASA Astrophysics Data System (ADS)

    Bailey, E.; Stevenson, D. J.

    2015-12-01

    We present a range of models of Uranus and Neptune, taking into account recent experimental data (Bali, 2013) implying the location of the critical curve of the H2-H2O system at pressures up to 2.6 GPa. The models presented satisfy the observed total mass of each planet and the radius at the observed 1-bar pressure level. We assume the existence of three regions at different depths: an outer adiabatic envelope composed predominately of H2 and He, with a helium mass fraction 0.26, a water-rich layer including varied amounts of rock and hydrogen, and a chemically homogeneous rock core. Using measured rotation rates of Uranus and Neptune, and a density profile obtained for each model using constituent equations of state and the assumption of hydrostatic equilibrium, we calculate the gravitational harmonics J2 and J4 for comparison with observed values as an additional constraint. The H2-H2O critical curve provides information about the nature of the boundary between the outer, hydrogen-rich envelope and underlying water-rich layer. The extrapolated critical curve for hydrogen-water mixtures crosses the adiabat of the outer atmospheric shell in these models at two depths, implying a shallow outer region of limited miscibility, an intermediate region between ~90 and 98 percent of the total planet radius within which hydrogen and water can mix in all proportions, and another, deeper region of limited miscibility at less than ~90 percent of the total planet radius. The pressure and temperature of the gaseous adiabatic shell at the depth of the shallowest extent of the water-rich layer determines whether a gradual compositional transition or an ocean surface boundary may exist at depth in these planets. To satisfy the observed J2, the outer extent of the water-rich layer in these models must be located between approximately 80 and 85 percent of the total planet radius, within the deep region of limited H2-H2O miscibility, implying an ocean surface is possible within the

  11. Crystal structure of NH4[La(SO4)2(H2O)].

    PubMed

    Benslimane, Meriem; Redjel, Yasmine Kheira; Merazig, Hocine; Daran, Jean-Claude

    2015-06-01

    The principal building units in the crystal structure of ammonium aqua-bis(sulfato)-lanthanate(III) are slightly distorted SO4 tetra-hedra, LaO9 polyhedra in the form of distorted tricapped trigonal prisms, and NH4 (+) ions. The La(3+) cation is coordinated by eight O atoms from six different sulfate tetra-hedra, two of which are bidentate coordinating and four monodentate, as well as one O atom from a water mol-ecule; each sulfate anion bridges three La(3+) cations. These bridging modes result in the formation of a three-dimensional anionic [La(SO4)2(H2O)](-) framework that is stabilized by O-H⋯O hydrogen-bonding inter-actions. The disordered ammonium cations are situated in the cavities of this framework and are hydrogen-bonded to six surrounding O atoms. PMID:26090145

  12. Crystal structure of NH4[La(SO4)2(H2O)

    PubMed Central

    Benslimane, Meriem; Redjel, Yasmine Kheira; Merazig, Hocine; Daran, Jean-Claude

    2015-01-01

    The principal building units in the crystal structure of ammonium aqua­bis(sulfato)­lanthanate(III) are slightly distorted SO4 tetra­hedra, LaO9 polyhedra in the form of distorted tricapped trigonal prisms, and NH4 + ions. The La3+ cation is coordinated by eight O atoms from six different sulfate tetra­hedra, two of which are bidentate coordinating and four monodentate, as well as one O atom from a water mol­ecule; each sulfate anion bridges three La3+ cations. These bridging modes result in the formation of a three-dimensional anionic [La(SO4)2(H2O)]− framework that is stabilized by O—H⋯O hydrogen-bonding inter­actions. The disordered ammonium cations are situated in the cavities of this framework and are hydrogen-bonded to six surrounding O atoms. PMID:26090145

  13. Structural reinvestigation of the photoluminescent complex [NdCl2(H2O)6]Cl.

    PubMed

    Hsieh, Kuan-Ying; Bendeif, El-Eulmi; Pillet, Sebastien; Doudouh, Abdelatif; Schaniel, Dominik; Woike, Theo

    2013-09-01

    The structure of the photoluminescent compound hexaaquadichloridoneodymium(III) chloride has been redetermined from single-crystal X-ray diffraction data at 100 K, with the aim of providing an accurate structural model for the bulk crystalline material. The crystal structure may be described as a network of [NdCl2(H2O)6](+) cations with distorted square-antiprism geometry around the Nd(III) centre. The Nd(III) cation and the nonbonded Cl(-) anion are both located on twofold symmetry axes. The crystal packing consists of three different neodymium pairs linked by a three-dimensional network of O-H···Cl intermolecular interactions. The pair distribution function (PDF) calculated from the experimentally determined structure is used for the discussion of the local structure. PMID:24005508

  14. Molecular Behavior CO2 and CO2-H2O Mixtures at Interfaces

    NASA Astrophysics Data System (ADS)

    Cole, D. R.; Chialvo, A.; Rother, G.; Vlcek, L.

    2010-12-01

    Injection of CO2 into subsurface geologic formations has been identified as a key strategy for mitigating the impact of anthropogenic emissions of CO2. Regardless of the formation type, the CO2 will encounter a complex heterogeneous porous matrix with widely varying pore size and pore distribution, interconnectivity, and surface composition. A small but non-trivial percentage of the pore space is comprised of voids that range from 100 nm down to a few nm in size. These nanoporous environments are more dominant in the cap or seal rocks, such as shale or clay-rich mudstones that act as confining barriers to leakage of CO2 out of the storage reservoir. A concern is the prevention of leakage from the host formation by an effective cap or seal rock which has low porosity and permeability characteristics. Shales comprise the majority of cap rocks encountered in subsurface injection sites with pore sizes typically less than 100 nm and whose surface chemistries are dominated by quartz (SiO2) and clays. We investigated the behavior of pure CO2 and CO2-H2O mixtures interacting with simple substrates, e.g. SiO2 and muscovite, that act as proxies for more complex mineralogical systems. SANS results were described for sorption properties of supercritical CO2 inside mesoporous silica aerogel (95% porosity; 5-40 nm pores), a proxy for the quartz sub-system. The Adsorbed Phase Model (APM) allows, for the first time, a means to quantify the physical properties (e.g. excess, absolute and total adsorption) of the adsorbed phase formed by fluids inside porous media in terms of the mean density and volume of the sorption phase. The results show clear evidence for fluid depletion for conditions above the critical density. Classical molecular dynamics (CMD) modeling of CO2-silica aerogel interactions also indicates the presence of fluid depletion for conditions above the critical density consistent with SANS results. CMD was also used to assess the microscopic behavior of CO2-H2O mixture

  15. Synergistic WO3·2H2O Nanoplates/WS2 Hybrid Catalysts for High-Efficiency Hydrogen Evolution.

    PubMed

    Yang, Lun; Zhu, Xiaobin; Xiong, Shijie; Wu, Xinglong; Shan, Yun; Chu, Paul K

    2016-06-01

    Tungsten trioxide dihydrate (WO3·2H2O) nanoplates are prepared by in situ anodic oxidation of tungsten disulfide (WS2) film on carbon fiber paper (CFP). The WO3·2H2O/WS2 hybrid catalyst exhibits excellent synergistic effects which facilitate the kinetics of the hydrogen evolution reaction (HER). The electrochromatic effect takes place via hydrogen intercalation into WO3·2H2O. This process is accelerated by the desirable proton diffusion coefficient in the layered WO3·2H2O. Hydrogen spillover from WO3·2H2O to WS2 occurs via atomic polarization caused by the electric field of the charges on the planar defect or edge active sites of WS2. The optimized hybrid catalyst presents a geometrical current density of 100 mA cm(-2) at 152 mV overpotential with a Tafel slope of ∼54 mV per decade, making the materials one of the most active nonprecious metal HER catalysts. PMID:27211828

  16. Spectroscopic measurement of HO2, H2O2, and OH in the stratosphere

    NASA Technical Reports Server (NTRS)

    Park, J. H.; Carli, B.

    1991-01-01

    Stratospheric concentrations of HO2, H2O2, and OH have been retrieved simultaneously from the far-infrared emission spectra obtained with a balloon-borne Fourier transform spectrometer in June 1983 at 32 deg N latitude. Retrieved concentrations of HO2 and H2O2 are reported, along with vertical distributions of OH which were reported in an earlier paper for the afternoon, sunset, and nighttime periods for altitudes from 26 to 38 km. HO2 distributions are obtained with uncertainties that are about the same as OH for the same vertical range and for the afternoon and sunset periods. H2O2 concentration is obtained at an altitude of 30 km for the period that covers afternoon and sunset hours. The retrieved concentrations of these HO(x) species agree well with other individually measured results and the steady state photochemical predictions. The ratio HO2/OH at around 32 km seems to increase from the afternoon period to the sunset period.

  17. The H2O2-H2O Hypothesis: Extremophiles Adapted to Conditions on Mars?

    NASA Astrophysics Data System (ADS)

    Houtkooper, Joop M.; Schulze-Makuch, Dirk

    2007-08-01

    The discovery of extremophiles on Earth is a sequence of discoveries of life in environments where it had been deemed impossible a few decades ago. The next frontier may be the Martian surface environment: could life have adapted to this harsh environment? What we learned from terrestrial extremophiles is that life adapts to every available niche where energy, liquid water and organic materials are available so that in principle metabolism and propagation are possible. A feasible adaptation mechanism to the Martian surface environment would be the incorporation of a high concentration of hydrogen peroxide in the intracellular fluid of organisms. The H2O2-H2O hypothesis suggests the existence of Martian organisms that have a mixture of H2O2 and H2O instead of salty water as their intracellular liquid (Houtkooper and Schulze-Makuch, 2007). The advantages are that the freezing point is low (the eutectic freezes at 56.5°C) and that the mixture is hygroscopic. This would enable the organisms to scavenge water from the atmosphere or from the adsorbed layers of water molecules on mineral grains, with H2O2 being also a source of oxygen. Moreover, below its freezing point the H2O2-H2O mixture has the tendency to supercool. Hydrogen peroxide is not unknown to biochemistry on Earth. There are organisms for which H2O2 plays a significant role: the bombardier beetle, Brachinus crepitans, produces a 25% H2O2 solution and, when attacked by a predator, mixes it with a fluid containing hydroquinone and a catalyst, which produces an audible steam explosion and noxious fumes. Another example is Acetobacter peroxidans, which uses H2O2 in its metabolism. H2O2 plays various other roles, such as the mediation of physiological responses such as cell proliferation, differentiation, and migration. Moreover, most eukaryotic cells contain an organelle, the peroxisome, which mediates the reactions involving H2O2. Therefore it is feasible that in the course of evolution, water-based organisms

  18. NO Removal in High Pressure Plasmas of N_2/H_2O/NO Mixtures

    NASA Astrophysics Data System (ADS)

    Fresnet, F.; Baravian, G.; Magne, L.; Pasquiers, S.; Postel, C.; Puech, V.; Rousseau, A.

    2001-10-01

    Influence of H_2O on NO removal has been studied using a homogeneous photo-triggered discharge with a time resolved LIF measurement of the NO density, in N_2/H_2O/NO mixtures at 460 mbar. The H_2O maximum concentration was 2.5 was between 70 and 160 J/l. Measurement of NO density has been performed up to 180 µs after the current pulse excitation of short duration, 50 ns. Kinetic analysis has been made using a self-consistent 0D-discharge model. NO is in great part dissociated, in N_2/NO, through collisions with the excited singlet states of N_2. We have previously shown that addition of ethene induces de-excitation of these states, leading to a decrease of the NO removal ( F. Fresnet, G. Baravian, L. Magne, S. Pasquiers, C. Postel, V. Puech, A. Rousseau, Appl. Phys. Lett., 77 (2000) 4118.). Similar processes take place when C_2H4 is replaced by H_2O. The value of the rate constant for collision of singlet states with water, 3.10-10 cm^3 s-1, is obtained from our study.

  19. Refinements in an Mg/MgH2/H2O-Based Hydrogen Generator

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    Some refinements have been conceived for a proposed apparatus that would generate hydrogen (for use in a fuel cell) by means of chemical reactions among magnesium, magnesium hydride, and steam. The refinements lie in tailoring spatial and temporal distributions of steam and liquid water so as to obtain greater overall energy-storage or energy-generation efficiency than would otherwise be possible. A description of the prior art is prerequisite to a meaningful description of the present refinements. The hydrogen-generating apparatus in question is one of two versions of what was called the "advanced hydrogen generator" in "Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators" (NPO-43554), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 52. To recapitulate: The apparatus would include a reactor vessel that would be initially charged with magnesium hydride. The apparatus would exploit two reactions: The endothermic decomposition reaction MgH2-->Mg + H2, which occurs at a temperature greater than or equal to 300 C, and The exothermic oxidation reaction MgH2 + H2O MgO + 2H2, which occurs at a temperature greater than or equal to 330 C.

  20. Particle-in-Cell Simulations of Atmospheric Pressure He/2%H2O Discharges

    NASA Astrophysics Data System (ADS)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.; Graves, D. B.; Gopalakrishnan, R.

    2015-09-01

    Atmospheric pressure micro-discharges in contact with liquid surfaces are of increasing interest, especially in the bio-medical field. We conduct 1D3v particle-in-cell (PIC) simulations of a voltage-driven 1 mm width atmospheric pressure He/2% H2O plasma discharge in series with an 0.5 mm width liquid H2O layer and a 1mm width quartz dielectric layer. A previously developed two-temperature hybrid global model of atmospheric pressure He/H2O discharges was used to determine the most important species and collisional reactions to use in the PIC simulations. We found that H13O6+, H5O3-, and electrons were the most prominent charged species, while most of the metastable helium He* was quenched via Penning ionization. The ion-induced secondary emission coefficient γi was assumed to be 0.15 at all surfaces. A series of simulations were conducted at 27.12 MHz with Jrf ~ 800-2200 A/m2. The H2O rotational and vibrational excitation losses were so high that electrons reached the walls at thermal temperatures. We also simulated a much lower frequency case of 50 kHz with Vrf = 10 kV. In this case, the discharge ran in a pure time-varying γ-mode. This work was supported by the Department of Energy Office of Fusion Energy Science Contract DE-SC0001939.

  1. Removal of Boron in Silicon by H2-H2O Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Andersson, Stefan; Nordstrand, Erlend; Tangstad, Merete

    2012-08-01

    The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52 ppm initially to 0.7 ppm and 3.4 ppm at 1450°C and 1500°C, respectively, after blowing a H2-3.2%H2O gas mixture for 180 min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.

  2. Novel soft-chemistry route of Ag2Mo3O10·2H2O nanowires and in situ photogeneration of a Ag@Ag2Mo3O10·2H2O plasmonic heterostructure.

    PubMed

    Hakouk, Khadija; Deniard, Philippe; Lajaunie, Luc; Guillot-Deudon, Catherine; Harel, Sylvie; Wang, Zeyan; Huang, Baibiao; Koo, Hyun-Joo; Whangbo, Myung-Hwan; Jobic, Stéphane; Dessapt, Rémi

    2013-06-01

    Ultrathin Ag2Mo3O10·2H2O nanowires (NWs) were synthesized by soft chemistry under atmospheric pressure from a hybrid organic-inorganic polyoxometalate (CH3NH3)2[Mo7O22] and characterized by powder X-ray diffraction, DSC/TGA analyses, FT-IR and FT-Raman spectroscopies, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their diameters are a few tens of nanometers and hence much thinner than that found for silver molybdates commonly obtained under hydrothermal conditions. The optical properties of Ag2Mo3O10·2H2O NWs before and after UV irradiation were investigated by UV-vis-NIR diffuse reflectance spectroscopy revealing, in addition to photoreduction of Mo(6+) to Mo(5+) cations, in situ photogeneration of well-dispersed silver Ag(0) nanoparticles on the surface of the NWs. The resulting Ag@Ag2Mo3O10·2H2O heterostructure was confirmed by electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and Auger spectroscopy. Concomitant reduction of Mo(6+) and Ag(+) cations under UV excitation was discussed on the basis of electronic band structure calculations. The Ag@Ag2Mo3O10·2H2O nanocomposite is an efficient visible-light-driven plasmonic photocatalyst for degradation of Rhodamine B dye in aqueous solution. PMID:23679344

  3. ACIDIFICATION OF RAIN IN THE PRESENCE OF SO2, H2O2, O3, AND HNO3

    EPA Science Inventory

    The production of acid sulfate and the accumulation of acid nitrate are calculated for falling raindrops using a physico-chemical model that accounts for the mass transfer of SO2, H2O2, O3, HNO3, and CO2. The acidification is postulated to occur through the absorption of free gas...

  4. Computational study on the negative electron affinities of NO2 -.(H2O)n clusters (n=0-30).

    PubMed

    Ejsing, Anne Marie; Brøndsted Nielsen, Steen

    2007-04-21

    Here we report negative electron affinities of NO(2)(-).(H2O)n clusters (n=0-30) obtained from density functional theory calculations and a simple correction to Koopmans' theorem. The method relies on the calculation of the detachment energy of the monoanion and its highest occupied molecular orbital and lowest unoccupied molecular orbital energies, and explicit calculations on the dianion itself are avoided. A good agreement with resonances in the cross section for neutral production in electron scattering experiments is found for n=0, 1, and 2. We find several isomeric structures of NO(2)(-).(H2O)2 of similar energy that elucidate the interplay between water-water and ion-water interactions. The topology is predicted to influence the electron affinity by 0.5 and 0.4 eV for NO(2)(-).(H2O) and NO(2)(-).(H2O)2, respectively. The electron affinity of larger clusters is shown to follow a (n+delta)-1/3 dependence, where delta=3 represents the number of water molecules that in volume, could replace NO(2) (-). PMID:17461632

  5. Synthesis and the crystal and molecular structure of the silver(I)-germanium(IV) polymeric complex with citrate anions {[Ag2Ge(H Cit)2(H2O)2] • 2H2O} n

    NASA Astrophysics Data System (ADS)

    Sergienko, V. S.; Martsinko, E. E.; Seifullina, I. I.; Churakov, A. V.; Chebanenko, E. A.

    2016-03-01

    The synthesis and X-ray diffraction study of compound {[Ag2Ge(H Cit)2(H2O)2] • 2H2O} n , where H4 Cit is the citric acid, are performed. In the polymeric structure, the H Cit 3- ligand fulfils the tetradentate chelate-μ4-bridging (3Ag, Ge) function (tridentate with respect to Ge and Ag atoms). The Ge atom is octahedrally coordinated by six O atoms of two H Cit 3-ligands. The coordination polyhedron of the Ag atom is an irregular five-vertex polyhedron [four O atoms of four H Cit 3- ligands and the O(H2O) atom]. An extended system of O-H···O hydrogen bonds connects complex molecules into a supramolecular 3D-framework.

  6. Selective synthesis of 3-hydroxy acids from Meldrum's acids using SmI2-H2O.

    PubMed

    Szostak, Michal; Spain, Malcolm; Procter, David J

    2012-05-01

    The single-step synthesis of 3-hydroxy carboxylic acids from readily available Meldrum's acids involves a selective monoreduction using a SmI(2)-H(2)O complex to give products in high crude purity, and it represents a considerable advancement over other methods for the synthesis of 3-hydroxy acids. The protocol includes a detailed guide to the preparation of a single electron-reducing SmI(2)-H(2)O complex and describes two representative examples of the methodology: monoreduction of a fully saturated Meldrum's acid (5-(4-bromobenzyl)-2,2-dimethyl-1,3-dioxane-4,6-dione) and tandem conjugate reduction-selective monoreduction of α,β-unsaturated Meldrum's acid (5-(4-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione). The protocol for selective monoreduction of Meldrum's acids takes ∼6 h to complete. PMID:22538848

  7. Acidification of rain in the presence of SO2, H2O2, O3, and HNO3

    SciTech Connect

    Overton, J.H. Jr; Durham, J.L.

    1982-01-01

    The production of acid sulfate and the accumulation of acid nitrate are calculated for falling raindrops using a physico-chemical model that accounts for the mass transfer of SO2, H2O2, O3, HNO3, and CO2. The acidification is postulated to occur through the absorption of free gaseous HNO3 and the absorption and reaction of SO2, H2O2, and O3 to yield H2SO4. Investigated are the relative effectivness of H2O2(aq) and O3(aq) for oxidizing SO2(aq) to yield H(+1) and SO-2(-2), and the role of HNO3(aq) in acidifying raindrops and influencing SO4(-2) formation. Results indicate: that H2O2 is more effective than O3, HNO3 inhibits SO4(-2) formation due to O3 oxidation, and in all cases, HNO3 is important in acidifying rain.

  8. Raman spectroscopic quantitative study of NaCl-CaCl2-H2O system at high temperatures and pressures.

    PubMed

    Li, Jing; Mao, Shi-De; Zheng, Hai-Fei

    2014-07-01

    Raman spectra features of the ternary system NaCl-CaCl2-H2O under high temperatures and high pressures were systematically studied in the present work by using hydrothermal diamond anvil cell (HDAC) and Raman shifts of quartz to determine pressures, and it has been obtained for the quantitative relationship between Raman shifts of the O-H stretching band of water, mass fractions of solutes and pressures was obtained. The mass fractions of salts, where salinity of NaCl equal to that of CaCl2, are 4.0 mass %, 8.0 mass %, and 12.0 mass %, respectively. Experimental results indicate that the standardized Raman frequency shift differences of the O-H stretching vibration (deltav(O0H)) rise with the increasing temperatures when the mass fractions of salts and pressures of the NaCl-CaCl2-H2O system remain constant. deltav(O-H) increases with the increase in mass fractions of salts in the system when the temperatures and pressures are constant. Linear relationship between deltav(O-H) and pressure with similar slopes can be found for the NaCl-CaCl2-H2O system with different salinities. The quantitative relationship between deltav(O-H), temperature (T), pressure (P), and mass fraction of solute (M) is P = -31.892 deltav(O-H) + 10.131T + 222.816M - 3 183.567, where the valid PTM range of the equation is 200 MPa < or = P < or = 1 700 MPa, 273 K < or = T < or = 539 K and M < or = 12 mass %. The equation can be used as a geobarometer in the studies of fluid inclusions of NaCl-CaCl2-H2O system with equal salinities. The method, as a direct geological detecting technique, has a potential application value. PMID:25269273

  9. The Crystal Structure of Synthetic Autunite, Ca[(UO2)(PO4)]2(H2O)11

    NASA Astrophysics Data System (ADS)

    Locock, A. J.; Burns, P. C.

    2002-05-01

    Autunite, Ca[(UO2)(PO4)]2(H2O)11, is amongst the most abundant and widely distributed of the uranyl phosphate minerals, yet because of its pseudo-tetragonal symmetry and rapid dehydration behavior, the details of its symmetry, stoichiometry and structure remain uncertain. The crystal structure of autunite was solved by direct methods and refined by full-matrix least-squares techniques to agreement indices wR2 = 0.125 for all data, and R1 = 0.042, calculated for the 1497 unique observed reflections. Autunite is orthorhombic, space group Pnma, Z = 4, a = 14.0135(6), b = 20.7121(8), c = 6.9959(3) Å, V = 2030.55(15) Å 3. Intensity data were collected using MoK-alpha radiation and a CCD-based area detector. The structure contains the well-known autunite type sheet with composition [(UO2)(PO4)]1-, resulting from the sharing of equatorial vertices of the uranyl square bipyramids with the phosphate tetrahedra. Calcium in the interlayer is coordinated by seven H2O groups and two longer distances to uranyl ion oxygen atoms. In addition, there are two symmetrically independent H2O groups held in the structure only by H-bonding. The structures of other members of the autunite group: orthorhombic synthetic Sr[(UO2)(PO4)]2(H2O)11, triclinic synthetic Ni[(UO2)(PO4)]2(H2O)12 and tetragonal zeunerite, Cu[(UO2)(AsO4)]2(H2O)12, will also be discussed.

  10. Crystal structures of [Mn(bdc)(Hspar)2(H2O)0.25]·2H2O containing MnO6+1 capped trigonal prisms and [Cu(Hspar)2](bdc)·2H2O containing CuO4 squares (Hspar = sparfloxacin and bdc = benzene-1,4-di­carboxyl­ate)

    PubMed Central

    An, Zhe; Gao, Jing; Harrison, William T. A.

    2016-01-01

    The syntheses and crystal structures of 0.25-aqua­(benzene-1,4-di­carboxyl­ato-κ2 O,O′)bis­(sparfloxacin-κ2 O,O′)manganese(II) dihydrate, [Mn(C8H4O4)(C19H22F2N4O3)2(H2O)0.25]·2H2O or [Mn(bdc)(Hspar)2(H2O)0.25]·2H2O, (I), and bis­(sparfloxacin-κ2 O,O′)copper(II) benzene-1,4-di­carboxyl­ate dihydrate, [Cu(C19H22F2N4O3)2](C8H4O4)·2H2O or [Cu(Hspar)2](bdc)·2H2O, (II), are reported (Hspar = sparfloxacin and bdc = benzene-1,4-di­carboxyl­ate). The Mn2+ ion in (I) is coordinated by two O,O′-bidentate Hspar neutral mol­ecules (which exist as zwitterions) and an O,O′-bidentate bdc dianion to generate a distorted MnO6 trigonal prism. A very long bond [2.580 (12) Å] from the Mn2+ ion to a 0.25-occupied water mol­ecule projects through a square face of the prism. In (II), the Cu2+ ion lies on a crystallographic inversion centre and a CuO4 square-planar geometry arises from its coordination by two O,O′-bidentate Hspar mol­ecules. The bdc dianion acts as a counter-ion to the cationic complex and does not bond to the metal ion. The Hspar ligands in both (I) and (II) feature intra­molecular N—H⋯O hydrogen bonds, which close S(6) rings. In the crystals of both (I) and (II), the components are linked by N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds, generating three-dimensional networks. PMID:26870595

  11. Crystal structures of [Mn(bdc)(Hspar)2(H2O)0.25]·2H2O containing MnO6+1 capped trigonal prisms and [Cu(Hspar)2](bdc)·2H2O containing CuO4 squares (Hspar = sparfloxacin and bdc = benzene-1,4-di-carboxyl-ate).

    PubMed

    An, Zhe; Gao, Jing; Harrison, William T A

    2016-01-01

    The syntheses and crystal structures of 0.25-aqua-(benzene-1,4-di-carboxyl-ato-κ(2) O,O')bis-(sparfloxacin-κ(2) O,O')manganese(II) dihydrate, [Mn(C8H4O4)(C19H22F2N4O3)2(H2O)0.25]·2H2O or [Mn(bdc)(Hspar)2(H2O)0.25]·2H2O, (I), and bis-(sparfloxacin-κ(2) O,O')copper(II) benzene-1,4-di-carboxyl-ate dihydrate, [Cu(C19H22F2N4O3)2](C8H4O4)·2H2O or [Cu(Hspar)2](bdc)·2H2O, (II), are reported (Hspar = sparfloxacin and bdc = benzene-1,4-di-carboxyl-ate). The Mn(2+) ion in (I) is coordinated by two O,O'-bidentate Hspar neutral mol-ecules (which exist as zwitterions) and an O,O'-bidentate bdc dianion to generate a distorted MnO6 trigonal prism. A very long bond [2.580 (12) Å] from the Mn(2+) ion to a 0.25-occupied water mol-ecule projects through a square face of the prism. In (II), the Cu(2+) ion lies on a crystallographic inversion centre and a CuO4 square-planar geometry arises from its coordination by two O,O'-bidentate Hspar mol-ecules. The bdc dianion acts as a counter-ion to the cationic complex and does not bond to the metal ion. The Hspar ligands in both (I) and (II) feature intra-molecular N-H⋯O hydrogen bonds, which close S(6) rings. In the crystals of both (I) and (II), the components are linked by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds, generating three-dimensional networks. PMID:26870595

  12. Structural characterization of nanocrystalline CrOOH·2H2O aerogel by X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Erenburg, A.; Gartstein, E.; Landau, M.

    2005-01-01

    The nanostructured powder prepared by critical CO2 extraction of the urea-assisted wet chromia gel mixture at 373 K in vacuum was studied by X-ray diffraction techniques. Thermoanalytical methods showed the presence of the lattice water molecules in the resulting phase corresponding to a chemical formula CrOOH·2H2O. The CrOOH·2H2O nanocrystals of 3-5 nm in diameter were observed in transmission electron microscopy and their structure was derived from the Rietveld analysis in which the disorder contribution to the X-ray scattering was implemented. The structural model shows that the hexagonal unit cell of α-CrOOH undergoes monoclinic distortion with half of the O-2 anions and OH- groups being replaced by bonded water molecules in the three-dimensional packing resulting in half of the sites in regular Cr+3 octahedra being vacant. Further examination of the quasi-crystalline disordered state of the CrOOH·2(H2O) nanocrystals was performed by model independent method of Radial Distribution Function (RDF). This complementary technique is sensitive to the molecular composition and allows to assess the average atomic (or electron) density distribution and the spacings of the atomic arrangements in the nearest neighbor shells comprising the range of the crystalline order in the structure of this material.

  13. Synthesis, characterization and solid-state properties of [Zn(Hdmmthiol)2]\\cdot2H2O complex

    NASA Astrophysics Data System (ADS)

    Dagdelen, Fethi; Aydogdu, Yildirim; Dey, Kamalendu; Biswas, Susobhan

    2016-05-01

    The zinc(II) complex with tridentate thiohydrazone ligand have been prepared by metal template reaction. The metal template reaction was used to prepare the zinc (II) complex with tridentate thiohydrazone ligand. The reaction of diacetylmonoxime and, morpholine N-thiohydrazidewith Zn(OAc)2 \\cdot2H2O under reflux yielded the formation of the [Zn(Hdmmthiol )2]\\cdot2H2O complex. The complex was characterized by a combination of protocols including elemental analysis, UV+vis, FT-IR, TG and PXRD. The temperature dependence of the electrical conductivity and the optical property of the [Zn(Hdmmthiol )2] \\cdot2H2O complex is called H2dammthiol was studied. Powder X-ray diffraction (PXRD) method was used to investigate the crystal structure of the sample. The zinc complex was shown to be a member of the triclinic system. The zinc complex was determined to have n-type conductivity as demonstrated in the hot probe measurements. The complex was determined to display direct optical transition with band gaps of 2.52eV as determined by the optical absorption analysis.

  14. The vibration-rotation-tunneling levels of N2-H2O and N2-D2O

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Carrington, Tucker

    2015-07-01

    In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.

  15. The vibration-rotation-tunneling levels of N2-H2O and N2-D2O.

    PubMed

    Wang, Xiao-Gang; Carrington, Tucker

    2015-07-14

    In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments. PMID:26178101

  16. Crystal Structures and Thermal Properties of Two Transition-Metal Compounds {[Ni(DNI)2(H2O)3][Ni(DNI)2 (H2O)4]}·6H2O and Pb(DNI)2(H2O)4 (DNI = 2,4-Dinitroimidazolate)

    PubMed Central

    Zhang, Guo-Fang; Cai, Mei-Yu; Jing, Ping; He, Chong; Li, Ping; Zhao, Feng-Qi; Li, Ji-Zhen; Fan, Xue-Zhong; Ng, Seik Weng

    2010-01-01

    Two transition-metal compounds derived from 2,4-dinitroimidazole, {[Ni(DNI)2(H2O)3][Ni(DNI)2 (H2O)4]}·6H2O, 1, and Pb(DNI)2(H2O)4, 2, were characterized by elemental analysis, FT-IR, TG-DSC and X-ray single-crystal diffraction analysis. Crystal data for 1: monoclinic, space group C2/c, a = 26.826(3), b = 7.7199(10), c = 18.579(2) Å, β = 111.241(2)° and Z = 4; 2: monoclinic, space group C2/c, a = 6.5347(6), b = 17.1727(17), c = 14.1011(14) Å, β = 97.7248(10) and Z = 4. Compound 1 contains two isolated nickel centers in its structure, one being six-coordinate and another five-coordinate. The structure of 2 contains a lead (II) center surrounded by two chelating DNI ligands and four water molecules in distorted square-antiprism geometry. The abundant hydrogen bonds in two compounds link the molecules into three-dimensional network and stabilize the molecules. The TG-DSC analysis reveals that the first step is the loss of water molecules and the final residue is the corresponding metal oxides and carbon. PMID:20526419

  17. Improved characterization of soil organic matter by thermal analysis using CO2/H2O evolved gas analysis.

    PubMed

    Fernández, José M; Peltre, Clément; Craine, Joseph M; Plante, Alain F

    2012-08-21

    Simultaneous thermal analysis [i.e., thermogravimetry (TG) and differential scanning calorimetry (DSC)] is frequently used in materials science applications and is increasingly being used to study soil organic matter (SOM) stability. Yet, important questions remain, especially with respect to how the soil mineral matrix affects TG-DSC results, which could confound the interpretation of relationships between thermal and biogeochemical SOM stability. The objective of this study was to explore the viability of using infrared gas analyzer (IRGA) based CO(2)/H(2)O evolved gas analysis (EGA) as a supplement or alternative to TG-DSC to improve the characterization of SOM. Here, we subjected reference samples and a set of 28 diverse soil samples from across the U.S. to TG-DSC coupled with IRGA-based EGA. The results showed the technical validity of coupling TG-DSC and CO(2)-EGA, with more than 80% of the theoretically evolved CO(2)-C recovered during pure cellulose and CaCO(3) analysis. CO(2)-EGA and DSC thermal profiles were highly similar, with correlation coefficients generally >0.90. Additionally, CO(2)/H(2)O-EGA proved useful to improve the accuracy of baseline correction, detect the presence of CaCO(3) in soils, and identify SOM oxidative reactions normally hidden in DSC analysis by simultaneous endothermic reactions of soil minerals. Overall, this study demonstrated that IRGA-based CO(2)/H(2)O-EGA constitutes a valuable complement to conventional TG-DSC analysis for SOM characterization. PMID:22809165

  18. Physical characterization and reactivity of the uranyl peroxide [UO2(η(2)-O2)(H2O)2]·2H2O: implications for storage of spent nuclear fuels.

    PubMed

    Mallon, Colm; Walshe, Aurora; Forster, Robert J; Keyes, Tia E; Baker, Robert J

    2012-08-01

    The unusual uranyl peroxide studtite, [UO(2)(η(2)-O(2))(H(2)O)(2)]·2H(2)O, is a phase alteration product of spent nuclear fuel and has been characterized by solid-state cyclic voltammetry. The voltammogram exhibits two reduction waves that have been assigned to the U(VI/V) redox couple at -0.74 V and to the U(V/IV) redox couple at -1.10 V. This potential shows some dependence upon the identity of the cation of the supporting electrolyte, where cations with larger ionic radii exhibit more cathodic reduction potentials. Raman spectroelectrochemistry indicated that exhaustive reduction at either potential result in a product that does not contain peroxide linkers and is likely to be UO(2). On the basis of the reduction potentials, the unusual behavior of neptunium in the presence of studtite can be rationalized. Furthermore, the oxidation of other species relevant to the long-term storage of nuclear fuel, namely, iodine and iodide, has been explored. The phase altered product should therefore be considered as electrochemically noninnocent. Radiotracer studies with (241)Am show that it does not interact with studtite so mobility will not be retarded in repositories. Finally, a large difference in band gap energies between studtite and its dehydrated congener metastudtite has been determined from the electronic absorption spectra. PMID:22813353

  19. [Cryogenic Raman spectroscopic characteristics of NaCl-H2O, CaCl2-H2O and NaCl-CaCl2-H2O: application to analysis of fluid inclusions].

    PubMed

    Mao, Cui; Chen, Yong; Zhou, Yao-Qi; Ge, Yun-Jin; Zhou, Zhen-Zhu; Wang, You-Zhi

    2010-12-01

    Accurately diagnosing the types of the salt and calculating the salinity quantitatively are the significant content of fluid inclusions. The traditional method of testing fluid inclusions salinity is cooling. To overcome the difficulty for observing freezing phase transition, the authors tested the spectrum of NaCl-H2O, CaCl2-H2O and NaCl-CaCl2-H2O systems at -180 degrees C by laser Raman spectroscopy. The result demonstrates that the ratio of peak values has linear relationship with salinity. Calibration curves were established by typical ratio of hydro-halite at 3 420 cm(-1) to the ice at 3 092 cm(-1), and the ratio of antarcticite at 3 432 cm(-1) to the ice at 3 092 cm(-1). The calibration curves have very high correlation coefficient. This method is verified by synthetic hydrocarbon-bearing aqueous fluid inclusions and quartz aqueous fluid inclusions of well Fengshen 6 in Dongying sag. The results of the authors' experiments show that cryogenic Raman spectroscopy can not only identify the types of the salts but also determine the salinity effectively in fluid inclusions. PMID:21322218

  20. Hydration of calcium sulfate hemihydrate (CaSO 4· {1}/{2}H 2O) into gypsum (CaSO 4·2H 2O). The influence of the sodium poly(acrylate)/surface interaction and molecular weight

    NASA Astrophysics Data System (ADS)

    Boisvert, Jean-Philippe; Domenech, Marc; Foissy, Alain; Persello, Jacques; Mutin, Jean-Claude

    2000-12-01

    The retarding influence of sodium poly(acrylate) (PANa) on the hydration of calcium sulfate hemihydrate (CaSO 4· {1}/{2}H 2O) was investigated. This study reports the influence of sodium poly(acrylate) on hemihydrate dissolution, on homogenous and heterogeneous gypsum (CaSO 4·2H 2O) nucleation as well as on gypsum growth. It is shown that adsorption of PANa does not hinder the dissolution of hemihydrate in the present experimental conditions. The specific interaction of PANa with gypsum can explain the oriented growth of gypsum crystal. The gypsum growth is slowed down but cannot be blocked by the adsorption of PANa. On the other hand, PANa can block the heterogeneous and homogenous gypsum nucleation. As soon as a critical surface density of PANa onto the hemihydrate surface is reached, the heterogeneous gypsum nucleation is prevented and hemihydrate hydration is indefinitely blocked. The interaction between PANa and the hemihydrate surface is of prime importance to control hydration. Also, the influence of the molecular weight of PANa on homogenous nucleation has been investigated. The precipitation of calcium polyacrylate can explain the differences between the two molecular weights used (2100 and 20 000). This work leads to the conclusion that heterogeneous nucleation is the key process that controls hydration of a system in which hemihydrate dissolution, gypsum nucleation and growth are all occurring at the same time in a continuous manner.

  1. Spin flop relaxation in the quasi-1d Heisenberg antiferromagnet CsMnBr 3 · 2H 2O

    NASA Astrophysics Data System (ADS)

    Chirwa, M.; Top, J.; Flokstra, J.

    1983-12-01

    The relaxation phenomena associated with the antiferromagnetic to spin-flop phase transition in the quasi one dimensional Heisenberg antiferromagnet CsMnBr 3 · 2H 2O have been determined in the temperature range 1.6-4.2 K using an automatic frequency-sweeping SQUID susceptometer. Below Tλ = 2.17 K the relaxation rate τ -1 displays an exponential temperature dependence given by τ-1 = ω0 exp(- E/ kT) where ω0 = 2.48 × 10 4 s -1 and E/ k = 3.62 K, the activation energy of the relaxation process. Above Tλ broadened absorption curves and flattened Argand diagrams are observed. The ratio K1/ K2 (=0.22 ± 0.02) of the orthorhombic anisotropy constants and a weak power-law temperature dependence of the critical spin-flop field Hcr were determined.

  2. Determination of muscle protein synthesis rates in fish using (2)H2O and (2)H NMR analysis of alanine.

    PubMed

    Marques, Cátia; Viegas, Filipa; Rito, João; Jones, John; Viegas, Ivan

    2016-09-15

    Following administration of deuterated water ((2)H2O), the fractional synthetic rate (FSR) of a given endogenous protein can be estimated by (2)H-enrichment quantification of its alanine residues. Currently, this is measured by mass spectrometry following a derivatization procedure. Muscle FSR was measured by (1)H/(2)H NMR analysis of alanine from seabass kept for 6 days in 5% (2)H-enriched saltwater, following acid hydrolysis and amino acid isolation by cation-exchange chromatography of muscle tissue. The analysis is simple and robust, and provides precise measurements of excess alanine (2)H-enrichment in the 0.1-0.4% range from 50 mmol of alanine recovered from muscle protein. PMID:27418547

  3. Electron paramagnetic resonance spectral study of [Mn(acs)2(2-pic)2(H2O)2] single crystals

    NASA Astrophysics Data System (ADS)

    Kocakoç, Mehpeyker; Tapramaz, Recep

    2016-03-01

    Acesulfame potassium salt is a synthetic and non-caloric sweetener. It is also important chemically for its capability of being ligand in coordination compounds, because it can bind over Nitrogen and Oxygen atoms of carbonyl and sulfonyl groups and ring oxygen. Some acesulfame containing transition metal ion complexes with mixed ligands exhibit solvato and thermo chromic properties and these properties make them physically important. In this work single crystals of Mn+2 ion complex with mixed ligand, [Mn(acs)2(2-pic)2(H2O)2], was studied with electron paramagnetic resonance (EPR) spectroscopy. EPR parameters were determined. Zero field splitting parameters indicated that the complex was highly symmetric. Variable temperature studies showed no detectable chance in spectra.

  4. Elucidating Protactinium Hydrolysis: The Relative Stabilities of PaO2(H2O)(+) and PaO(OH)2(+).

    PubMed

    Dau, Phuong D; Wilson, Richard E; Gibson, John K

    2015-08-01

    It is demonstrated that the gas-phase oxo-exchange of PaO2(+) with water is substantially faster than that of UO2(+), indicating that the Pa-O bonds are more susceptible to activation and formation of the bis-hydroxide intermediate, PaO(OH)2(+). To elucidate the nature of the water adduct of PaO2(+), hydration of PaO2(+) and UO2(+), as well as collision induced dissociation (CID) and ligand-exchange of the water adducts of PaO2(+) and UO2(+), was studied. The results indicate that, in contrast to UO2(H2O)(+), the protactinium oxo bis-hydroxide isomer, PaO(OH)2(+), is produced as a gas-phase species close in energy to the hydrate isomer, PaO2(H2O)(+). CID behavior similar to that of Th(OH)3(+) supports the assignment as PaO(OH)2(+). The gas-phase results are consistent with the spontaneous hydrolysis of PaO2(+) in aqueous solution, this in contrast to later AnO2(+) (An = U, Np, Pu), which forms stable hydrates in both solution and gas phase. In view of the known propensity for Th(IV) to hydrolyze, and previous gas-phase studies of other AnO2(+), it is concluded that the stabilities of oxo-hydroxides relative to oxide hydrates decreases in the order: Th(IV) > Pa(V) > U(V) > Np(V) > Pu(V). This trend suggests increasing covalency and decreasing ionicity of An-O bonds upon proceeding across the actinide series. PMID:26203499

  5. Structure and dynamics of forsterite-scCO2/H2O interfaces as a function of water content

    NASA Astrophysics Data System (ADS)

    Kerisit, Sebastien; Weare, John H.; Felmy, Andrew R.

    2012-05-01

    Molecular dynamics (MD) simulations of forsterite surfaces in contact with supercritical carbon dioxide (scCO2) fluids of varying water content were performed to determine the partition of water between the scCO2 fluid and the mineral surface, the nature of CO2 and H2O bonding at the interface, and the regions of the interface that may be conducive to HCO3(2-x)- formation. Calculations of the free energy of the associative adsorption of water onto the (0 1 0) forsterite surface from the scCO2 phase indicated that the formation of a water film up to three-monolayer thick can be exothermic even for water contents below the water saturation concentration of the scCO2 fluid. In MD simulations of scCO2/H2O mixtures in contact with the (0 1 0) forsterite surface, H2O was found to readily displace CO2 at the surface and, therefore, CO2 directly contacted the surface only for water coverages below two monolayers. For thicker water films, a two-monolayer hydration layer formed that CO2 could not penetrate. The MD simulations thus suggest that, in the presence of sufficient water, HCO3(2-x)- formation occurs in the water films and not via direct reaction of CO2 with the forsterite surface. Simulations of the hydroxylated (0 1 0) surface and of the (0 1 1) surface suggested that this conclusion can be extended to forsterite surfaces with different surface structures and/or compositions. The density, diffusion, and degree of hydration of CO2 as well as the extent of CO2/H2O mixing at the interface were all predicted to depend strongly on the thickness of the water-rich film, i.e., on the water content of the scCO2 fluid.

  6. Structure and Dynamics of Forsterite-scCO2/H2O Interfaces as a Function of Water Content

    SciTech Connect

    Kerisit, Sebastien N.; Weare, John H.; Felmy, Andrew R.

    2012-05-01

    Molecular dynamics (MD) simulations of forsterite surfaces in contact with supercritical carbon dioxide (scCO2) fluids of varying water content were performed to determine the partition of water between the scCO2 fluid and the mineral surface, the nature of CO2 and H2O bonding at the interface, and the regions of the interface that may be conducive to HxCO3(2-x)- formation. Calculations of the free energy of the associative adsorption of water onto the (010) forsterite surface from the scCO2 phase indicated that the formation of a water film up to three-monolayer thick can be exothermic even for water contents below the water saturation concentration of the scCO2 fluid. In MD simulations of scCO2/H2O mixtures in contact with the (010) forsterite surface, H2O was found to readily displace CO2 at the surface and, therefore, CO2 directly contacted the surface only for water coverages below two monolayers. For thicker water films, a two-monolayer hydration layer formed that CO2 could not penetrate. Simulations of the hydroxylated (010) surface and of the (011) surface suggested that this conclusion can be extended to forsterite surfaces with different surface structures and/or compositions. The density, diffusion, and degree of hydration of CO2 as well as the extent of CO2/H2O mixing at the interface were all predicted to depend strongly on the thickness of the water-rich film, i.e., on the water content of the scCO2 fluid.

  7. Magnetic Phase Transition of the Mixed Antiferromagnets Ni1-xMxCl2·2H2O (M=Co, Mn)

    NASA Astrophysics Data System (ADS)

    Hamasaki, T.; Zenmyo, K.; Kubo, H.

    2012-12-01

    Mixed antiferromagnets Ni1-xMxCl2·2H2O (M=Co, Mn) were prepared. The crystal structure of NiCl2-2H2O is a little different from that of CoCl2·2H2O and MnCl2·2H2O. In order to examine how Co or Mn spins in NiCl2·2H2O crystal structure behave, we determined precisely the phase transition temperatures by measuring the specific heats and have obtained the concentration dependence of the phase transition temperature. Substitution of Co for Ni increases a little the transition temperature and contrary to this the substitution of Mn decreases the transition temperature rapidly. The results are discussed on the basis of molecular field theory. In the case of M=Co, the concentration dependence of the phase transition temperature is well explained by molecular field theory. But, in the case of M=Mn, the molecular field theory cannot explain it sufficiently. Thus Mn spins in NiCl2·2H2O crystal show the peculiar behavior. We suppose that this may be attributed to a kind of the instability of Mn spins.

  8. Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

    PubMed

    Pathak, A K; Mukherjee, T; Maity, D K

    2007-07-28

    We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters. PMID:17672687

  9. Interplay of magnetic sublattices in langite Cu4(OH)6SO4 · 2H2O

    NASA Astrophysics Data System (ADS)

    Lebernegg, S.; Tsirlin, A. A.; Janson, O.; Redhammer, G. J.; Rosner, H.

    2016-03-01

    Magnetic and crystallographic properties of the mineral langite Cu4(OH)6SO{}4\\cdot 2H2O are reported. Thermodynamic measurements combined with a microscopic analysis, based on density-functional bandstructure calculations, identify a quasi-two-dimensional (2D), partially frustrated spin-1/2 lattice resulting in the low Néel temperature of {T}{{N}}≃ 5.7 K. This spin lattice splits into two parts with predominant ferro- and antiferromagnetic (AFM) exchange couplings, respectively. The former, ferromagnetic (FM) part is prone to the long-range magnetic order and saturates around 12 T, where the magnetization reaches 0.5 {μ }{{B}}/Cu. The latter, AFM part features a spin-ladder geometry and should evade long-range magnetic order. This representation is corroborated by the peculiar temperature dependence of the specific heat in the magnetically ordered state. We argue that this separation into ferro- and antiferromagnetic sublattices is generic for quantum magnets in Cu2+ oxides that combine different flavors of structural chains built of CuO4 units. To start from reliable structural data, the crystal structure of langite in the 100-280 K temperature range has been determined by single-crystal x-ray diffraction, and the hydrogen positions were refined computationally.

  10. Measurements of Flow Distortion within the IRGASON Integrated Sonic Anemometer and CO_2/H_2O Gas Analyzer

    NASA Astrophysics Data System (ADS)

    Horst, T. W.; Vogt, R.; Oncley, S. P.

    2016-07-01

    Wind-tunnel and field measurements are analyzed to investigate flow distortion within the IRGASON integrated sonic anemometer and CO_2/H_2O gas analyzer as a function of wind speed, wind direction and attack angle. The wind-tunnel measurements are complimentary to the field measurements, and the dependence of the wind-tunnel mean-wind-component flow-distortion errors on wind direction agrees well with that of the field measurements. The field measurements exhibit significant overestimation of the crosswind variance and underestimation of the momentum flux with respect to an adjacent CSAT3 sonic, as well as a transfer of turbulent kinetic energy from the streamwise wind component to the cross-stream wind components. In contrast, we find attenuation of only a few percent in the vertical velocity variance and the vertical flux of sonic temperature. The attenuation of the fluxes appears to be caused to a large extent by decorrelation between the horizontal and vertical-velocity components and between the vertical velocity and sonic temperature. Additional flow distortion due to transducer shadowing reduces to some extent the overestimation, but also increases the underestimation of the IRGASON turbulence statistics.

  11. Kinetic of the OH-radical in high pressure plasmas of N_2/H_2O/hydrocarbons mixtures

    NASA Astrophysics Data System (ADS)

    Baravian, G.; Fresnet, F.; Magne, L.; Pasquiers, S.; Postel, C.; Puech, V.; Rousseau, A.

    2001-10-01

    Kinetic of the OH-radical has been studied in homogeneous plasmas achieved in a photo-triggered discharge device, in N_2/H_2O with C_2H4 or C_3H_6, at 460 mbar with 1.2 concentration and a deposited energy in the plasma equal to 92 J/l. Hydrocarbon concentration ranged from 50 ppm up to 1000 ppm. Using the same technique as for NO kinetic studies ( F. Fresnet, G. Baravian, L. Magne, S. Pasquiers, C. Postel, V. Puech, A. Rousseau, Appl. Phys. Lett., 77 (2000) 4118.), a time resolved LIF diagnostic has been performed to measure the OH-radical density up to 180 µs after the short current pulse excitation, 50 ns. At fixed deposited energy, the LIF signal rapidly decreases when hydrocarbon concentration increases. Measurements have been compared to predictions of a self-consistent 0D-model which takes into account a detailed kinetic scheme, including oxidation reactions of hydrocarbons by the radical which are important processes in flue gas non-thermal plasma treatment. Results are discussed.

  12. Measurements of Flow Distortion within the IRGASON Integrated Sonic Anemometer and CO_2 /H_2 O Gas Analyzer

    NASA Astrophysics Data System (ADS)

    Horst, T. W.; Vogt, R.; Oncley, S. P.

    2016-02-01

    Wind-tunnel and field measurements are analyzed to investigate flow distortion within the IRGASON integrated sonic anemometer and CO_2 /H_2 O gas analyzer as a function of wind speed, wind direction and attack angle. The wind-tunnel measurements are complimentary to the field measurements, and the dependence of the wind-tunnel mean-wind-component flow-distortion errors on wind direction agrees well with that of the field measurements. The field measurements exhibit significant overestimation of the crosswind variance and underestimation of the momentum flux with respect to an adjacent CSAT3 sonic, as well as a transfer of turbulent kinetic energy from the streamwise wind component to the cross-stream wind components. In contrast, we find attenuation of only a few percent in the vertical velocity variance and the vertical flux of sonic temperature. The attenuation of the fluxes appears to be caused to a large extent by decorrelation between the horizontal and vertical-velocity components and between the vertical velocity and sonic temperature. Additional flow distortion due to transducer shadowing reduces to some extent the overestimation, but also increases the underestimation of the IRGASON turbulence statistics.

  13. Structure and properties of the (HCl)2H2O cluster observed by chirped-pulse Fourier transform microwave spectroscopy.

    PubMed

    Kisiel, Zbigniew; Lesarri, Alberto; Neill, Justin L; Muckle, Matt T; Pate, Brooks H

    2011-08-21

    The rotational spectrum of the cyclic (HCl)(2)H(2)O cluster has been identified for the first time in the chirped pulse, Fourier transform microwave spectrum of a supersonically expanded HCl/H(2)O/Ar mixture. The spectrum was measured at frequencies 6-18.5 GHz, and transitions in two inversion-tunneling states, at close to 1 : 3 relative intensity, have been assigned for the parent species. The two single (37)Cl isotopic species, and the double (37)Cl species have been assigned in the natural abundance sample, and the (18)O and HDO species of the cluster were identified in isotopically enriched samples. The rich nuclear quadrupole hyperfine structure due to the presence of two chlorine nuclei has been satisfactorily fitted and provided useful information on the nonlinearity of intermolecular bonds in the cluster. The r(s) heavy atom geometry of the cluster was determined and the strongest bond in the intermolecular cycle r(O···HCl) = 3.126(3) Å, is found to be intermediate in length between the values in H(2)O···HCl and (H(2)O)(2)HCl. The fitted spectroscopic constants and derived molecular properties are compared with ab initio predictions, and a discussion of complexation effects in these three clusters is made. PMID:21743896

  14. Novel design of an enclosed CO2/H2O gas analyser for eddy covariance flux measurements

    NASA Astrophysics Data System (ADS)

    Burba, G. G.; McDermitt, D. K.; Anderson, D. J.; Furtaw, M. D.; Eckles, R. D.

    2010-11-01

    ABSTRACT This study describes design and field performance of a new enclosed CO2/H2O gas analyser, LI-7200. Unlike present closed-path analysers, this new instrument is designed for operation with short intake tubes, with the intention to maximize strengths and to minimize weaknesses of both traditional open-path and closed-path approaches. The study provides description of the instrument, shows the principles of its operation, and explains advantages of a new design. Field results are provided from three field experiments with the prototypes, and cover such parameters as high frequency air temperature and pressure fluctuations inside the sampling cell versus ambient conditions, instantaneous concentrations and cospectra for CO2 and H2O in comparison with open-path instrument, and eddy covariance hourly CO2 and H2O fluxes in comparison with both open-path and closed-path instruments. Field data loss inventory is also provided in comparison with open-path and closed-path gas analysers. The new enclosed design results in little data loss during precipitation and icing, similar to the closed-path design, but with a low power consumption and high field stability comparable to open-path instruments.

  15. FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT Drought(s)-Elimination FOREVER!!!

    NASA Astrophysics Data System (ADS)

    Ertl, G.; Alefeld, G.; Youdelis, W.; Radd, H.; Oertle, G.; Siegel, Edward

    2011-03-01

    "H2O H2O everywhere; ne'er a drop to drink"[Coleridge(1798)]; now: "H2 H2 everywhere; STILL ne'er a drop to drink": ONLY H2 (or methane CH4) can be FLYING-WATER(F-W) chemical-rain-in-pipelines Hindenberg-effect (H2-UP;H2O-DOWN): {O/H2O}=[16]/[18] 90 % ; O already in air uphill; NO H2O pumping need! In global-warming driven H2O-starved glacial-melting world, rescue is possible ONLY by Siegel [{3rd Intl. Conf. Alt.-Energy }(1980)-vol.5/p.459!!!] Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating-system. Rosenfeld[Science 315,1396(3/9/2007)]-Biello [Sci.Am.(3/9/2007)] crucial geomorph-ology which ONLY maximal-buoyancy H2 can exploit, to again make "Mountains into Fountains", ``upthrust rocks trapping the clouds to precipitate their rain/snow/H2O'': "terraforming"(and ocean-rebasificaton!!!) Siegel proprietary magnetic-hydrogen-valve (MHV) permits H2 flow in already in-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Science 300,1740(2003)] dire warning of global-pandemics (cancers/ blindness/famine) Hydrogen-economy CATASTROPHIC H2 ozone-layer destruction sobering cavat to dangerous H2-automotion-economy panacea hype!!!

  16. Reactions of acetone oxide stabilized Criegee intermediate with SO2, NO2, H2O and O3

    NASA Astrophysics Data System (ADS)

    Kukui, Alexandre; Chen, Hui; Xiao, Shan; Mellouki, Wahid; Daële, Veronique

    2015-04-01

    Atmospheric aerosol particles represent a critical component of the atmosphere, impacting global climate, regional air pollution, and human health. The formation of new atmospheric particles and their subsequent growth to larger sizes are the key processes for understanding of the aerosol effects. Sulphuric acid, H2SO4, has been identified to play the major role in formation of new atmospheric particles and in subsequent particle growth. Until recently the reaction of OH with SO2 has been considered as the only important source of H2SO4 in the atmosphere. However, recently it has been suggested that the oxidation of SO2 by Criegee biradicals can be a significant additional atmospheric source of H2SO4 comparable with the reaction of SO2 with OH. Here we present some results about the reactions of the acetone oxide stabilized Criegee intermediate, (CH3)2=OO, produced in the reaction of 2,3-dimethyl-butene (TME) with O3. The formation of the H2SO4 in the reaction of acetone oxide with SO2 was investigated in the specially constructed atmospheric pressure laminar flow reactor. The Criegee intermediate was generated by ozonolysis of TME. The H2SO4, generated by addition of SO2, was directly monitored with Chemical Ionization Mass Spectrometer (SAMU, LPC2E). Relative rates of reactions of acetone oxide with SO2, NO2, H2O and ozone were determined from the dependencies of the H2SO4 yield at different concentrations of the reactants. Atmospheric applications of the obtained results are discussed in relation to the importance of this additional H2SO4 formation pathway compared to the reaction of OH with SO2.

  17. FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT ETERNAL Drought(s)-Elimination FOREVER!!!

    NASA Astrophysics Data System (ADS)

    Wignall, J.; Lyons, Marv; Ertl, G.; Alefeld, Georg; Youdelis, W.; Radd, H.; Oertle, G.; Siegel, Edward

    2013-03-01

    ''H2O H2O everywhere; ne'er a drop to drink''[Coleridge(1798)] now: ''H2 H2 everywhere; STILL ne'er a drop to drink'': ONLY H2 (or methane CH4) can be FLYING-WATER(F-W) chemical-rain-in-pipelines Hindenberg-effect (H2-UP;H2O-DOWN): { ∖{}O/H2O{ ∖}} =[16]/[18] ∖sim 90{ ∖%} O already in air uphill; NO H2O pumping need! In global-warming driven H2O-starved glacial-melting world, rescue is possible ONLY by Siegel [ ∖underline {3rd Intl. Conf. Alt.-Energy }(1980)-vol.5/p.459!!!] Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating-system. Rosenfeld[Science 315,1396(3/9/2007)]-Biello [Sci.Am.(3/9 /2007)] crucial geomorphology which ONLY maximal-buoyancy H2 can exploit, to again make ''Mountains into Fountains'', ``upthrust rocks trapping the clouds to precipitate their rain/snow/H2O'': ''terraforming''(and ocean-rebasificaton!!!) ONLY VIA Siegel[APS March MTGS.:1960s-2000ss) DIFFUSIVE-MAGNETORESISTANCE (DMR) proprietary MAGNETIC-HYDROGEN-VALVE(MHV) ALL-IMPORTANT PRECLUDED RADIAL-diffusion, permitting ONLY AXIAL-H2-BALLISTIC-flow (``G.A''.''/DoE''/''Terrapower''/''Intellectual-Ventures''/ ''Gileland''/ ''Myhrvold''/''Gates'' ``ARCHIMEDES'') in ALREADY IN-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Science 300,1740(2003)] dire warning of global-pandemics (cancers/ blindness/ famine)

  18. Ordering of calcium and vacancies in calcium catapleiite CaZr[Si3O9] • 2H2O

    NASA Astrophysics Data System (ADS)

    Aksenov, S. M.; Portnov, A. M.; Chukanov, N. V.; Rastsvetaeva, R. K.; Nelyubina, Yu. V.; Kononkova, N. N.; Akimenko, M. I.

    2016-05-01

    A sample of holotypic calcium catapleiite from the Burpala alkaline massif (Northern Baikal, Russia) is studied by single crystal X-ray analysis at 120 K and IR spectroscopy. The empirical formula of calcium catapleiite is Ca0.97Na0.02Zr1.01Si3O9 • 2H2O ( Z = 4). The X-ray diffraction study confirms the orthorhombic unit cell with the following parameters: a = 7.406(1), b = 12.687(1), and c = 10.112(1) Å; V = 950.1(2) Å3; space group Pbnn. The crystal structure is refined in the anisotropic approximation of atomic displacement parameters using 1177 reflections with I > 2σ( I) to the final R = 2.91%. The structure of calcium catapleiite under study is based on the microporous heteropolyhedral framework formed by ZrO6 octahedra and threemembered silicon-oxygen rings [Si3O9]. It is on the whole analogous to the structures of the samples studied earlier, but differs from them by a high degree of ordering of calcium and vacancies at extraframework positions. The distribution of calcium over Ca1 and Ca2 positions in the calcium catapleiite structure leads to the formation of zigzag chains of the …Ca1-Zr-Ca1-Zr… and …Ca2-h-Ca2-□… types. Low occupancy of the Ca2 position and its alternation with the vacancy are prerequisites for potential Ca2+ cationic conduction.

  19. Calculation of the vapor-saturated liquidus for the NaCl-CO2-H2O system

    USGS Publications Warehouse

    Barton, P.B.; I-Ming, C.

    1993-01-01

    The polybaric liquidus surface for the H2O-rich corner of the NaCl-CO2-H2O ternary is calculated, relying heavily on 1. (1) a Henry's law equation for CO2 in brines (modified from Drummond, 1981), 2. (2) the assumption that the contributions of dissolved NaCl and CO2 in lowering the activity of H2O are additive, and 3. (3) data on the CO2 clathrate solid solution (nominally CO2 ?? 7.3H2O, but ranging from 5.75 to 8 or 9 H2O) from Bozzo et al. (1975). The variation with composition of the activity of CO2??7.3H2O, or any other composition within the clathrate field, is small, thereby simplifying the calculations appreciably. Ternary invariant points are 1. (1) ternary eutectic at -21.5??C, with ice + clathrate + hydrohalite NaCl-??H2O + brine mNaCl = 5.15, mco2 = 0.22 + vapor Ptotal ??? Pco2 = 5.7 atm; 2. (2) peritectic at -9.6??C, with clathrate + hydrohalite + liquid CO2 + brine mNaCl = 5.18, mco2 = 0.55 + vapor (Ptotal ??? Pco2 = 26.47 atm); and 3. (3) peritectic slightly below +0.1 ??C, with halite + hydrohalite + liquid CO2 + brine (mNaCl ??? 5.5, mco2 ??? 0.64) + vapor (Ptotal ??? Pco2 ??? 34 atm). CO2 isobars have been contoured on the ternary liquidus and also on the 25??C isotherm. An important caveat regarding the application of this information to the interpretation of the freezing-thawing behavior of fluid inclusions is that metastable behavior is a common characteristic of the clathrate. ?? 1993.

  20. Covalency hinders AnO2(H2O)(+)→ AnO(OH)2(+) isomerisation (An = Pa-Pu).

    PubMed

    Kaltsoyannis, Nikolas

    2016-02-21

    The enthalpies of the reactions AnO2(+)→ AnO(+) + O and AnO2(+) + H2O → AnO2(H2O)(+), and those of the isomerisation of the latter to AnO(OH)2(+), have been calculated for An = Pa-Pu. The data match previous experimental and computational values very closely, and the computed enthalpy for the isomerisation of PaO2(H2O)(+) to PaO(OH)2(+), requested by the authors of Inorg. Chem., 2015, 54, 7474, is found to be 0.8 kJ mol(-1). The NPA, NBO and QTAIM approaches are used to probe covalency in the An-Oyl bond of AnO2(H2O)(+), and all metrics agree that these bonds become increasingly covalent as the 5f series is crossed, providing rationalisation for the increasingly endothermic isomerisation reactions. QTAIM analysis indicates that the An=O and An-OH bonds in the oxide hydroxide isomers also become increasingly covalent as the 5f series is crossed. PMID:26781751

  1. One-step fabrication of nickel nanocones by electrodeposition using CaCl2·2H2O as capping reagent

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Jung, Kyung Kuk; Lee, Sung Ho; Ko, Jong Soo

    2016-04-01

    In this research, a method for the fabrication of nickel nanocones through the addition of CaCl2·2H2O to an electrodeposition solution was proposed. When electrodeposition was performed after CaCl2·2H2O addition, precipitation of the Ni ions onto the (2 0 0) crystal face was suppressed and anisotropic growth of the nickel electrodeposited structures was promoted. Sharper nanocones were produced with increasing concentration of CaCl2·2H2O added to the solution. Moreover, when temperature of the electrodeposition solutions approached 60 °C, the apex angle of the nanostructures decreased. In addition, the nanocones produced were applied to superhydrophobic surface modification using a plasma-polymerized fluorocarbon (PPFC) coating. When the solution temperature was maintained at 60 °C and the concentration of the added CaCl2·2H2O was 1.2 M or higher, the fabricated samples showed superhydrophobic surface properties. The proposed nickel nanocone formation method can be applied to various industrial fields that require metal nanocones, including superhydrophobic surface modification.

  2. Investigation of atmospheric profiles of CO2 & H2O using a novel coupled model - WRF-SPA

    NASA Astrophysics Data System (ADS)

    Smallman, L.; Moncrieff, J. B.; Williams, M.

    2012-04-01

    Vertical profiles of CO2 contain an important source of information about the distribution of sources and sinks of carbon in an ecosystem. Here, we have developed a forward running model based on combining WRF with SPA to generate vertical CO2 profiles for comparison with observations. We use these modelled profiles to infer the strength and distribution of sources and sinks of carbon and water. The specific aim of this research is to combine a high resolution (4 km) forward running meteorological model (WRF) with a modified version of a mechanistic biosphere model (SPA). The combined model is used to investigate the sources and sinks of CO2 and to explore which land surfaces contribute to vertical profiles of CO2 observed over Aberfeldy, Scotland. The profiles were collected as part of the Aerocarb, and later, CarboEurope projects. SPA provides surface fluxes calculated from coupled energy, hydrological and carbon cycles. This closely coupled representation of the biosphere provides realistic surface exchanges to drive mixing within the planetary boundary layer. In addition to the analysis of aircraft profiles, land based eddy covariance measurements of CO2, H2O and energy fluxes between the atmosphere and several different vegetation types (forest, grassland & crop land) are used for validation of surface fluxes and surface meteorology generated by WRF-SPA. Preliminary comparisons with observations has shown that WRF-SPA is capable of producing realistic annual fluxes of net carbon exchange compared to observations of a evergreen forest (obs = 3.6 tC ha-1 yr-1 ; modelled = 3.5 tC ha-1 yr-1 ) and barley field (obs = 2.6 tC ha-1 yr-1 ; modelled = 2.8 tC.ha-1 yr-1 ) during 2005 in Scotland. Forward running models have a potentially significant advantage over inverse models when investigating terrestrial carbon balance. For example, inverse models are able to model carbon sink distribution as areas which do not contribute CO2 to a given profile, while in a forward

  3. An experimental study iof the diffusion of C and O in calcite in mixed Co2-H2O fluids.

    SciTech Connect

    Labotka, Theodore C.; Cole, David; Fayek, Mostafa; Chacko, Thomas {nmn}

    2011-01-01

    The diffusivity of C and O in calcite in mixed CO2-H2O fluid was determined over the range in xCO2 from 1.0 to about 0.2 at 700 C, 100 MPa, with selected experiments conducted at pressures to 250 MPa and temperatures of 600 and 800 C. The diffusivity of C, DC, varies little with xCO2, although there is some evidence for a slight increase in DC from 5 10 18 to 5 10 17 cm2/s with decreasing xCO2. Our data and those of others are consistent with a model for DC 1/fCO2. Despite the large uncertainty, we observed that the diffusivity of O, DO, increases from 2 10 16 to 5 10 14 cm2/s with xCO2 decreasing from 1.0 to 0. There is a good correlation at 700 C between log DO and log fH2O regardless of the total pressure, matching the observations of previous workers. The data are consistent with a simple two-component model for the diffusion of O in calcite, one component for diffusion in the presence of CO2 and one in the presence of H2O: DO = DOCO2 + DOH2O aH2O. The activity of H2O is relative to the fugacity at 100 MPa, 700 C. DOCO2 is 3.45 10 16, and DOH2O is 3.8 10 14 cm2/s. The data indicate that the rate of diffusion of C and O in calcite is controlled by reactions at the surface of calcite. Adsorption of H2O and the creation of vacancies at the surface account for the dependence of the diffusivity on the fugacity of the fluid components. There is little evidence that H itself diffuses into calcite. With this model and the values of DO in pure CO2 (Labotka et al. 2000) and in pure H2O (Farver 1994), the value of DO is predicted over the temperature range 600 800 C and pH2O up to 300 MPa, the range of the data. Calculated closure temperatures for diffusive exchange of O between calcite and fluid are reduced by about 150 C in the presence of an aqueous fluid.

  4. Phase Relations In The System MgO-SiO2-H2O At Lower Mantle Conditions

    NASA Astrophysics Data System (ADS)

    Walter, M. J.; Frost, J.; Kohn, S. C.; WANG, W.; Thomson, A. R.; Lord, O. T.

    2013-12-01

    Transport of water into the lower mantle within subducted slabs has important implications for understanding chemical mass transfer and dynamics in the deep mantle. Dehydration of the slab in the upper mantle strips the slab of much of its water cargo, however, a significant amount of water can be retained in nominally anhydrous phases such as olivine and its high-pressure polymorphs, and pyroxenes. These phases are not stable beyond the transition zone, and water may become bound in high-pressure, dense hydrous silicates, such as Phase D, and transported into the lower mantle. Here we report on experiments in the System MgO-SiO2-H2O made in the laser-heated diamond anvil cell in the pressure range of 25 to 60 GPa and at temperatures of ~1400 to 2000 K. Starting materials are synthesized as mixtures of MgSiO3 and SiO2 glasses plus brucite, have a range of water contents of ~ 5 to 30 mol% H2O, and include both MgO-rich (model peridotite) and SiO2-rich (model eclogite) bulk compositions. Experiments are made using multi-chambered (three or four laser-drilled 25 micron holes) Re gaskets. In order to avoid Al2O3 contamination, a ruby grain is inserted into only one of the chambers for initial pressure measurement. Post-heating pressures are measured in all chambers from the calibrated shift of the Raman singlet peak of diamond that is related to stress at the culet surface. Run products are analyzed using a combination of synchrotron X-ray diffraction and FEG-EPMA to identify synthesized phases and textural relations. Perturbations in the laser-power vs temperature function that correlate with visual movement of the sample and post-quench textural features are interpreted as the hydrous silicate solidus. We will discuss the implications of the following observations: (1) The hydrous silicate melting curve occurs at ~ 1750 to 1950 K for all compositions over the studied pressure range, (2) Phase D has a high-pressure stability limit that is only mildly dependent on

  5. LiOH - H2O2 - H2O trinary system study for the selection of optimal conditions of lithium peroxide synthesis

    NASA Astrophysics Data System (ADS)

    Nefedov, R. A.; Ferapontov, Yu A.; Kozlova, N. P.

    2016-01-01

    Using solubility method the decay kinetics of peroxide products contained in liquid phase of LiOH - H2O2 - H2O trinary system with 2 to 6% by wt hydrogen peroxide content in liquid phase in 21 to 33 °C temperature range has been studied. Conducted studies have allowed to determine temperature and concentration limits of solid phase existence of Li2O2·H2O content, distinctness of which has been confirmed using chemical and qualitative X- ray phase analysis. Stabilizing effect of solid phase of Li2O2·H2O content on hydrogen peroxide decay contained in liquid phase of LiOH - H2O2 - H2O trinary system under conditions of experiments conducted has been shown.

  6. Synthesis, crystal structure and EPR studies of vanadyl doped [Co(2-nbH)2(ina)2(H2O)] complex

    NASA Astrophysics Data System (ADS)

    Bozkurt, Esat; Çelik, Yunus; Çöpür, Fatma; Dege, Necmi; Topcu, Yıldıray; Karabulut, Bünyamin

    2016-08-01

    A novel aquabis(isonicotinamide-κN1)bis(2-nitrobenzoato-κ2O,O‧;κO)cobalt(II), (hereafter [Co(2-nbH)2(ina)2(H2O)]; 2-nbH: 2-nitrobenzoic acid; ina: isonicotinamide), complex was synthesized and characterized by using various techniques. The crystal structure was determined by X-ray diffraction (XRD) method. The magnetic properties of VO2+ doped [Co(2-nbH)2(ina)2(H2O)] complex were obtained by electron paramagnetic resonance (EPR) technique. The angular variation of EPR spectra shows that two different VO2+ complexes are present in the lattice. The FT-IR spectra of this compound were discussed in relation to other compounds containing 2-nitrobenzoato or isonicotinamide ligands. Thermal stability and reactivity of this complex were also studied by thermal analysis methods (TG/DTG/DTA).

  7. Supramolecular arrangement promoted in trans-[PdCl2(HONC10H14O)2]·2H2O by hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Galvão, Adelino M.; Carvalho, M. Fernanda N. N.; Grilo, António L.

    2014-05-01

    Palladium(II) complexes trans-[PdCl2(3-HONC10H14O)2]ṡ2H2O and trans-[PdCl2(2-HONC10H16)2] with similar formulations and molecular geometries display considerably different supramolecular arrangements due to hydrogen bonding involving the oxime substituent (NOH) of the camphor ligand, the halide co-ligand of adjacent molecules and H2O outer-sphere molecules in the case of trans-[PdCl2(3-HONC10H14O)2]ṡ2H2O. The discussion is based on data collected by X-ray diffraction analysis and DFT calculations.

  8. The phase diagrams and Pitzer model representations for the system KCl + MgCl2 + H2O at 50 and 75°C

    NASA Astrophysics Data System (ADS)

    Yang, Ji-min; Peng, Jing; Duan, Yu-xia; Tian, Chong; Ping, Mei

    2012-12-01

    The solubilities in the KCl-MgCl2-H2O system were determined at 50 and 75°C and the phase diagrams and the diagram of refractive index vs composition were plotted. Two invariant point, three univariant curves, and three crystallization zones, corresponding to potassium chloride, hexahydrate (MgCl2 · 6H2O) and double salt (KCl · MgCl2 · 6H2O) showed up in the phase diagrams of the ternary system, The mixing parameters θK, Ca and ΨK, Ca, Cl and equilibrium constant K sp were evaluated in KCl-MgCl2-H2O system by least-squares optimization procedure, in which the single-salt Pitzer parameters of KCl and MgCl2 β(0), β(1), β(2), and C ϕ were directly calculated from the literature. The results obtained were in good agreement with the experimental data.

  9. Hydrothermal synthesis and characterization of the lutetium borate-nitrate Lu2B2O5(NO3)2·2H2O

    NASA Astrophysics Data System (ADS)

    Ortner, Teresa S.; Wurst, Klaus; Hejny, Clivia; Huppertz, Hubert

    2016-01-01

    The lutetium diborate-dinitrate Lu2B2O5(NO3)2·2H2O was discovered through a hydrothermal synthesis from Lu(NO3)3·H2O and H3BO3. The compound crystallizes in the space group P 1 ̅ (no. 2) with the lattice parameters a=789.52(5), b=988.62(6), c=1460.33(8) pm, α=90.83(1), β=101.75(1), and γ=110.02(1)° (Z=4). Isolated [B2O5]4- units show coplanar alignment and the coordinating [NO3]- groups are stacked perpendicular to the borate plane. Thereby, a novel, open arrangement solely built up from diborate and nitrate groups at a 1:1 ratio is formed. Additionally, Lu2B2O5(NO3)2·2H2O is characterized by vibrational spectroscopy (IR/Raman).

  10. Experimental determination and model simulation of the solid-liquid equilibria in the ZnSO4-Zn(OH)2-H2O system

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoya; Yin, Xia; Chen, Zifang; Yu, Xiuli; Zeng, Dewen; Tan, Yuqi

    2015-06-01

    The solubility data and pH of the ZnSO4-Zn(OH)2-H2O system were elaborately measured at T = 291.15, 298.15, 308.15, and 323.15 K, and the solid phases were determined by XRD to be ZnSO4 · 3Zn(OH)2 · 5H2O. The Pitzer model was applied to simulate thermodynamically and predict the relationship between mass percent of ZnSO4 and pH in the ZnSO4-Zn(OH)2-H2O system taking account of the equilibrium of ions over the temperature from 273.15 to 323.15 K. Based on the experimental data and the calculation results, a theoretical direction of avoiding base zinc sulfate forming in industrial processes was advised.

  11. Nqrs Data for C8H9KO6 [C8H5KO4·2(H2O)] (Subst. No. 1092)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H9KO6 [C8H5KO4·2(H2O)] (Subst. No. 1092)

  12. Stochastic jumps of magnetization in [Mn{(R/S)-pn}]2[Mn{(R/S)-pn}2(H2O)][Cr(CN)6]2 molecular magnet

    NASA Astrophysics Data System (ADS)

    Kirman, M. V.; Talantsev, A. D.; Koplak, O. V.; Morgunov, R. B.

    2015-03-01

    Series of stochastic jumps of the magnetic moment (up to five individual jumps) have been observed at the demagnetization of single crystals of [Mn{(R/S)-pn}]2[Mn{(R/S)-pn}2(H2O)][Cr(CN)6]2 molecular magnet in a narrow range of magnetic fields near the coercive force ( H c = 7.5 Oe). The magnetic field at which jumps of the magnetization arise decreases with an increase in the temperature.

  13. High-performance flexible electrochromic device based on facile semiconductor-to-metal transition realized by WO3·2H2O ultrathin nanosheets

    PubMed Central

    Liang, Lin; Zhang, Jiajia; Zhou, Yingying; Xie, Junfeng; Zhang, Xiaodong; Guan, Meili; Pan, Bicai; Xie, Yi

    2013-01-01

    Ultrathin nanosheets are considered as one kind of the most promising candidates for the fabrication of flexible electrochromic devices (ECDs) due to their permeable channels, high specific surface areas, and good contact with the substrate. Herein, we first report the synthesis of large-area nanosheets of tungsten oxide dihydrate (WO3·2H2O) with a thickness of only about 1.4 nm, showing much higher Li+ diffusion coefficients than those of the bulk counterpart. The WO3·2H2O ultrathin nanosheets are successfully assembled into the electrode of flexible electrochromic device, which exhibits wide optical modulation, fast color-switching speed, high coloration efficiency, good cyclic stability and excellent flexibility. Moreover, the electrochromic mechanism of WO3·2H2O is further investigated by first-principle density functional theory (DFT) calculations, in which the relationship between structural features of ultrathin nanosheets and coloration/bleaching response speed is revealed. PMID:23728489

  14. Infrared absorption spectra of the CO(2)/H(2)O complex in a cryogenic nitrogen matrix--detection of a new bending frequency.

    PubMed

    Zhang, Xu; Sander, Stanley P

    2011-09-01

    Infrared absorption spectra have been measured for the mixture of CO(2) and H(2)O in a cryogenic nitrogen matrix. The 1:1 CO(2)/H(2)O complex has been observed. Each structure of this complex should have two bending frequencies corresponding to the CO(2) fundamental bending mode (ν(2)). In this work, three bending frequencies corresponding to the CO(2) fundamental bending mode (ν(2)) have been detected; one of them at 660.3 cm(-1) is reported here for the first time. This finding helps confirm the existence of two structures for this complex. A new feature attributed to a CO(2) and H(2)O complex is observed at 3604.4 cm(-1) and is tentatively assigned to the CO(2)/H(2)O complex band corresponding to the CO(2) combination mode (ν(3) + 2ν(2)). In addition, a band that belongs to a CO(2) and H(2)O complex is detected at 3623.8 cm(-1) for the first time and is tentatively assigned to the (CO(2))(2)/H(2)O complex band corresponding to the symmetric stretching mode (ν(1)) of H(2)O. PMID:21702496

  15. Constructing three-dimensional quasi-vertical nanosheet architectures from self-assemble two-dimensional WO3·2H2O for efficient electrochromic devices

    NASA Astrophysics Data System (ADS)

    Li, Haizeng; Wang, Jinmin; Shi, Qiuwei; Zhang, Minwei; Hou, Chengyi; Shi, Guoying; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang; Chi, Qijin

    2016-09-01

    Three-dimensional (3D) quasi-vertical nanosheet (QVNS) architectures are of great importance in the application of electrochromic devices due to its 3D porous structures, large surface area and lamellar permeable space of nanosheets. In this study, we demonstrate successful preparing of WO3·2H2O nanosheets via a novel and facile solution route and repurposing the typical electrodeposition technique to obtain 3D QVNS electrodes. The electrode was successfully assembled into an electrochromic device which exhibits good electrochromic performance.

  16. Rovibrational analysis of the water bending vibration in the mid-infrared spectrum of atmospherically significant N2-H2O complex

    NASA Astrophysics Data System (ADS)

    Springer, S. D.; McElmurry, B. A.; Wang, Z.; Leonov, I. I.; Lucchese, R. R.; Bevan, J. W.; Coudert, L. H.

    2015-07-01

    Rovibrational transitions associated with tunneling states in the water bending vibration of the atmospherically significant N2-H2O complex have been recorded using a cw supersonic jet quantum cascade laser spectrometer at 6.2 μm. Analysis of the observed spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data. This accounts for Coriolis coupling to obtain the levels of the ground vibrational state and confirmation of assignment of the excited water bending vibration. The results are used to explore the nature of the associated water bending vibrationally excited states of the complex compared to those in other corresponding water complexes.

  17. Raman spectroscopic analysis of supersaturated aqueous solution of MgO·B 2O 3-32%MgCl 2-H 2O during acidification and dilution

    NASA Astrophysics Data System (ADS)

    Zhihong, Liu; Bo, Gao; Shuni, Li; Mancheng, Hu; Shuping, Xia

    2004-11-01

    Raman spectra of supersaturated aqueous solution of MgO·B 2O 3-32%MgCl 2-H 2O during acidification/alkalization and dilution have been studied. The assignments of the recorded Raman shift are given. The main existing forms of polyborate anions and their interaction in borate aqueous solution have been proposed through spectroscopic analysis. The experimental results indicate that the higher concentration of cation are beneficial not only to the dissolution of boric acid but also to the polymerization of polyborate anions. The existing forms and interaction among them also depend on the concentration of boron and the pH value in solution.

  18. A new acid-base indicator containing complex: Hydrothermal synthesis, crystal structure and properties of [Cd(en)2(H2O)2](MO)2

    NASA Astrophysics Data System (ADS)

    Ma, Kui-Rong; Shi, Jing; Zhang, Dao-Jun; Xu, Jia-Ning

    2012-04-01

    The first example of cadmium complex containing methyl orange [MO, (CH3)2NC6H4N = NC6H4SO3Na], formulated as [Cd(en)2(H2O)2](MO)21 (en = ethylenediamine) was synthesized hydrothermally and characterized by single-crystal X-ray diffraction, IR, XRD, elemental analysis and Raman spectroscopic analysis. Compound 1 display a two-dimensional supramolecular layer structure with ladder-like supramolecular chain by X-ray crystallographic analysis. MO anion immobilized by H-bonds, as acid-base indicator, shows a similar behavior in comparison with its solution counterpart in terms of response to pH.

  19. A Raman spectroscopic study of the basic carbonate mineral callaghanite Cu2Mg2(CO3)(OH)6ṡ2H2O

    NASA Astrophysics Data System (ADS)

    Čejka, Jiří; Sejkora, Jiří; Jebavá, Ivana; Xi, Yunfei; Couperthwaite, Sara J.; Frost, Ray L.

    2013-05-01

    Raman spectrum of callaghanite, Cu2Mg2(CO3)(OH)6ṡ2H2O, was studied and compared with published Raman spectra of azurite, malachite and hydromagnesite. Stretching and bending vibrations of carbonate and hydroxyl units and water molecules were tentatively assigned. Approximate O-H…O hydrogen bond lengths were inferred from the spectra. Because of the high content of hydroxyl ions in the crystal structure in comparison with low content of carbonate units, callaghanite should be better classified as a carbonatohydroxide than a hydroxycarbonate.

  20. The phase equilibriums in the NH4Cl-CaCl2-H2O system at 50 and 75°C and their Pitzer model representations

    NASA Astrophysics Data System (ADS)

    Zhang, Run-Zhi; Yang, Ji-Min; Zhang, Li; Xu, Chun-Yan

    2014-12-01

    The solubilities and refractive indexes in the NH4Cl-CaCl2-H2O system were measured at 50 and 75°C and the phase diagrams were constructed on the basis of the experimental data. The mixing parameters and equilibrium constant K sp were evaluated using the Pitzer ion-interaction model representations. The results obtained were in good agreement with the experimental data. The mixed parameters of Pitzer ion-interaction model and equilibrium constant obtained in the work can furthermore be applied to solubility predictions of more complicated systems containing NH4Cl and CaCl2.

  1. Clathration of Two-Dimensional Coordination Polymers: Synthesis and Structures of [M(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)Bpy) (M = Cd(II), Zn(II) and bpy = Bipyridine).

    PubMed

    Tong, Ming-Liang; Ye, Bao-Hui; Cai, Ji-Wen; Chen, Xiao-Ming; Ng, Seik Weng

    1998-06-01

    In the presence of guest 2,4'-bpy molecules or under acidic conditions, three compounds, [Cd(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (1), [Zn(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (2), and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)bpy) (3), were obtained from the reactions of the metal salts and 4,4'-bpy in an EtOH-H(2)O mixture. 1 has a 2-D square-grid network structure, crystallizing in the monoclinic space group P2/n, with a = 13.231(3) Å, b = 11.669(2) Å, c = 15.019(3) Å, beta = 112.82(3) degrees, Z = 2; 2 is isomorphous with 1, crystallizing in the monoclinic space group P2/n, with a = 13.150(3) Å, b = 11.368(2) Å, c = 14.745(3) Å, beta = 110.60(3) degrees, Z = 2. The square grids superpose on each other into a channel structure, in which each layer consists of two pairs of shared edges, perfectly square-planar with an M(II) ion and a 4,4'-bpy at each corner and side, respectively. The square cavity has dimensions of 11.669(2) x 11.788(2) and 11.368(2) x 11.488(2) Å for 1 and 2, respectively. Every two guest 2,4'-bpy molecules are clathrated in each hydrophobic host cavity and are further stabilized by pi-pi stacking and hydrogen bonding interactions. The NMR spectra clearly confirm that both 1 and 2 contain 4,4'-bpy and 2,4'-bpy molecules in a 1:1 ratio, which have stacking interaction with each other in the solution. 3 crystallizes in the orthorhombic space group Ibam, with a = 11.1283(5) Å, b = 15.5927(8) Å, c = 22.3178(11) Å, Z = 4. 3 is made up of two-dimensional square [Cu(4)(4,4'-bpy)(4)] grids, where the square cavity has dimensions of 11.13 x 11.16 Å. Each [4,4'-H(2)bpy](2+) cation is clathrated in a square cavity and stacks with one pair of opposite edges of the host square cavity in an offset fashion with the face-to-face distance of ca. 3.95 Å. Within each cavity, the [4,4'-H(2)bpy](2+) cation forms twin three-center hydrogen bonds with two pairs of ClO(4)(-) anions. The results suggest that the

  2. Evaluation of Water Exchange Kinetics on [Ln(AAZTAPh-NO2)(H2O)q](x) Complexes Using Proton Nuclear Magnetic Resonance.

    PubMed

    Karimi, Shima; Tei, Lorenzo; Botta, Mauro; Helm, Lothar

    2016-06-20

    Water exchange kinetics on [Ln(AAZTAPh-NO2)(H2O)q](-) (Ln = Gd(3+), Dy(3+), or Tm(3+)) were determined by (1)H nuclear magnetic resonance (NMR) measurements. The number of inner-sphere water molecules was found to change from two to one when going from Dy(3+) to Tm(3+). The calculated water exchange rate constants obtained by variable-temperature proton transverse relaxation rates are 3.9 × 10(6), 0.46 × 10(6), and 0.014 × 10(6) s(-1) at 298 K for Gd(3+), Dy(3+), and Tm(3+), respectively. Variable-pressure measurements were used to assess the water exchange mechanism. The results indicate an associative and dissociative interchange mechanism for Gd(3+) and Dy(3+) complexes with ΔV(⧧) values of -1.4 and 1.9 cm(3) mol(-1), respectively. An associative activation mode (Ia or A mechanism) was obtained for the Tm(3+) complex (ΔV(⧧) = -5.6 cm(3) mol(-1)). Moreover, [Dy(AAZTAPh-NO2)(H2O)2](-) with a very high transverse relaxivity value was found as a potential candidate for negative contrast agents for high-field imaging applications. PMID:27227690

  3. Influence of lipids with hydroxyl-containing head groups on Fe2+ (Cu2+)/H2O2-mediated transformation of phospholipids in model membranes.

    PubMed

    Olshyk, Viktoriya N; Melsitova, Inna V; Yurkova, Irina L

    2014-01-01

    Under condition of ROS formation in lipid membranes, free radical reactions can proceed in both hydrophobic (peroxidation of lipids, POL) and polar (free radical fragmentation) parts of the bilayer. Free-radical fragmentation is typical for the lipids containing a hydroxyl group in β-position with respect to an ester or amide bond. The present study has been undertaken to investigate free-radical transformations of phospholipids in model membranes containing lipids able to undergo fragmentation in their polar part. Liposomes from egg yolk lecithin containing saturated or monounsaturated glycero- and sphingolipids were subjected to the action of an HO* - generating system - Fe(2+)(Cu(2+))/H2O2/Asc, and the POL products were investigated. In parallel with this, the effects of monoacylglycerols and scavengers of reactive species on Fe(2+)(Cu(2+))/H2O2/Asc - mediated free-radical fragmentation of phosphatidylglycerols were studied. Hydroxyl-containing sphingolipids and glycerolipids, which undergo free-radical fragmentation under such conditions, manifested antioxidant properties in the model membranes. In the absence of HO groups in the lipid structure, the effect was either pro-oxidant or neutral. Monoacylglycerols slowed down the rate of both peroxidation in the hydrophobic part and free-radical fragmentation in the hydrophilic part of phospholipid membrane. Scavengers of reactive species inhibited the fragmentation of phosphatidylglycerol substantially. Thus, the ability of hydroxyl-containing lipids to undergo free-radical fragmentation in polar part apparently makes a substantial contribution to the mechanism of their protector action. PMID:24189590

  4. Vibrational spectroscopic study of the mineral penkvilksite Na 2TiSi 4O 11.2H 2O - a mineral used for the uptake of radionuclides

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei

    2013-01-01

    We have used vibrational spectroscopy to study the formula and molecular structure of the mineral penkvilksite Na 2TiSi 4O 11.2H 2O. Penkvilksite is a mineral which may be used in the uptake of radioactive elements. Both Raman and infrared spectroscopies identify a band at ∼3638 cm-1 attributed to an OH-stretching vibration of hydroxyl units. The inference is that OH units are involved in the structure of penkvilksite. The formula may be well written as Na 2TiSi 4O 10(OH)2.H 2O. The mineral is characterised by a very intense Raman band at 1085 cm-1 and a broad infrared band at 1080 cm-1 assigned to SiO-stretching vibrations. Raman bands at 620, 667 and 711 cm-1 are attributed to SiO and TiO chain bonds. Water-stretching vibrations are observed as Raman bands at 3197, 3265, 3425 and 3565 cm-1. Vibrational spectroscopy enables aspects of the molecular structure of the mineral penkvilksite to be ascertained. Penkvilksite is a mineral which can incorporate actinides and lanthanides from radioactive waste.

  5. A SAFT equation of state for the quaternary H2S-CO2-H2O-NaCl system

    NASA Astrophysics Data System (ADS)

    Ji, Xiaoyan; Zhu, Chen

    2012-08-01

    Phase equilibria and thermodynamic properties of the quaternary H2S-CO2-H2O-NaCl system were studied using a statistical associating fluid theory (SAFT)-based equation of state (EOS) at temperatures from 0 to 200 °C (373.15-473.15 K), pressures up to 600 bar (60 MPa) and concentrations of NaCl up to 6 mol/kgH2O. The understanding of the physical-chemical properties of this system is critical for predicting the consequences of co-injection of CO2 and H2S into geological formations (geological carbon sequestration) as an option for mitigating the global warming trend. Equation of state parameters were generated from regression of available and reliable experimental data and incorporation of existing parameters for some subsystems. Densities were predicted and compared with available experimental results. Using the EOS developed in this study, we predicted equilibrium compositions in both liquid and vapor phases, fugacity coefficients of components, the equilibrium pressures at a given composition of the H2O-rich phase in electrolyte solutions with NaCl varying from 0 to 4 mol/kgH2O, and the aqueous solution densities. These predicted values are tabulated and available as supplementary data in the electronic version online. These predictions provide information and guidance for future experiments regarding the thermodynamic properties and phase behaviors in the H2S-CO2-H2O-NaCl system.

  6. Evidence of PVT anomaly boundaries of water at high pressure from compression and NaCl.2H2O dehydration experiments.

    PubMed

    Mirwald, P W

    2005-09-22

    Isothermal compression experiments on water have been performed between 0 to 80 degrees C and up to 1.3 GPa pressure. The compressibilities derived from the water compression experiments reveal a nonsmooth PVT behavior forming two anomaly boundaries. These boundaries originate at the melting line of ice III at about 0.25 GPa/-20 degrees C, and of ice VI at about 0.8 GPa/13 degrees C. Both boundaries have a positive sloped course separating three areas of different PVT properties of water. However, this P-T topology is obscured by an unresolved complication in the temperature range of 40-60 degrees C, which allows different topological interpretations of the data. As a cross-check for the compression experiment the dehydration boundary of sodium chloride-dihydrate (NaCl.2H2O) has been determined up to 1.5 GPa. The dehydration curve of NaCl.2H2O which traverses the two anomaly boundaries shows two inflections at the intersection, at 0.27 GPa/12 degrees C and at 0.77 GPa/22 degrees C, respectively. While the isothermal compressibility curves as well as the dP/dT course of the two anomaly boundaries give evidence of two densifications of water, the slope analysis of the inflections of the NaCl-2H2O dehydration curve suggests that the entropy change plays an important role. A recent model of water at high pressure conditions proposes a gradual structural transition from a low density water (LDW) at low pressures to a high density water (HDW) at high pressures. The compression data as well as the inflections of the dehydration boundary indicate, however, two discrete structural changes of water. Data comparison with that model suggests that the anomaly boundary at lower pressure corresponds to a volume fraction [V(HDW)/(V(LDW)+V(HDW))] of 0.8, while the upper one approaches a volume fraction of 1. PMID:16392519

  7. Structure, spectroscopy, and theory calculations of mononuclear mixed-ligand copper(II) complex with malonate and 2-propylimidazole, [Cu(mal)(PIM) 2(H 2O)

    NASA Astrophysics Data System (ADS)

    Peng, Xian; Cui, Guang-Hua; Li, De-Jie; Wu, Shang-Zhuo; Yu, Ya-Mei

    2010-05-01

    A mononuclear copper(II) complex, [Cu(mal)(PIM) 2(H 2O)] (1) [mal = malonate dianion, PIM = 2-propylimidazole] has been synthesized and characterized by elemental analysis, IR, UV-Vis, TG-DTA, and single crystal X-ray diffraction. The center Cu(II) atom in the complex has a distorted square-pyramidal geometry, being coordinated by two nitrogen atoms and three oxygen atoms. Density Functional Theory (DFT) with the B3LYP method and time-dependent DFT calculations were performed to provide insight into the structural, electronic, and electronic spectroscopic properties of the complex 1, and the UV-Vis spectrum of the title compound has been discussed on this basis. All the absorption bands in UV-Vis spectrum are mostly π/( P, σ) → d x2-y2 ligand-to-metal charge transfer (LMCT) transition, together with partial d → d ligand field (LF) transition.

  8. Pressure-Induced Magnetic Crossover Driven by Hydrogen Bonding in CuF2(H2O)2(3-chloropyridine)

    PubMed Central

    O'Neal, Kenneth R.; Brinzari, Tatiana V.; Wright, Joshua B.; Ma, Chunli; Giri, Santanab; Schlueter, John A.; Wang, Qian; Jena, Puru; Liu, Zhenxian; Musfeldt, Janice L.

    2014-01-01

    Hydrogen bonding plays a foundational role in the life, earth, and chemical sciences, with its richness and strength depending on the situation. In molecular materials, these interactions determine assembly mechanisms, control superconductivity, and even permit magnetic exchange. In spite of its long-standing importance, exquisite control of hydrogen bonding in molecule-based magnets has only been realized in limited form and remains as one of the major challenges. Here, we report the discovery that pressure can tune the dimensionality of hydrogen bonding networks in CuF2(H2O)2(3-chloropyridine) to induce magnetic switching. Specifically, we reveal how the development of exchange pathways under compression combined with an enhanced ab-plane hydrogen bonding network yields a three dimensional superexchange web between copper centers that triggers a reversible magnetic crossover. Similar pressure- and strain-driven crossover mechanisms involving coordinated motion of hydrogen bond networks may play out in other quantum magnets. PMID:25116701

  9. An Investigation of the Adsorption Characteristics of 5'ATP and 5'AMP onto the Surface of Caso4 x 2H2O

    NASA Technical Reports Server (NTRS)

    Calderon, J.; Sweeney, M. A.

    1984-01-01

    A model has been proposed in which solid surfaces can act as a site for cataletic activity of condensation reactions for certain biomolecules. From this model, the adsorption characteristics of 5'ATP and 5'AMP onto the surface of CaSO4.2H2O was chosen for study. It has been proven that 5'ATP and 5'AMP do adsorb onto the surface of CaSO4. Studies were then made to determine the dependence of absorption versus time, concentration, ionic strength and pH. It was found that the adsorption of the nucleotides is highly pH dependent, primarily determined by the phosphate acid groups of the nucleic acid molecule. From this investigation, the data obtained is discussed in relation to the model for the prebiotic earth.

  10. Effect of chirality on domain wall dynamics in molecular ferrimagnet [MnII(HL-pn)(H2O)][MnIII(CN)6]·2H2O

    NASA Astrophysics Data System (ADS)

    Mushenok, F.; Koplak, O.; Morgunov, R.

    2011-11-01

    In this paper we distinguish the contributions of switching, slide, creep and Debye relaxation modes of the domain wall dynamics to the low-frequency magnetic properties of chiral and racemic [MnII(HL-pn)(H2O)][MnIII(CN)6]·2H2O molecular ferrimagnets. We demonstrate that crystal and spin chirality affects the characteristic transition temperatures between different modes. In chiral crystals, transitions to the creep and Debye relaxation modes were observed at T = 7 K and 5 K, whereas in racemic crystals the same transitions occurred at higher temperatures T = 13 K and 9 K, respectively. Difference of the Peierls relief in chiral and racemic crystals is a possible reason of the chirality effect on the domain walls dynamics.

  11. NaKV4O9·2H2O: a new 2D magnetic compound with a 1/5-depleted square lattice.

    PubMed

    Cui, Meiyan; He, Zhangzhen; Wang, Nannan; Tang, Yingying; Guo, Wenbin; Zhang, Suyun; Wang, Lin; Xiang, Hongping

    2016-03-15

    A new vanadate compound NaKV4O9·2H2O is successfully synthesized by a conventional hydrothermal method. This compound crystallizes in the monoclinic system with the space group C2/c, showing a typical 2D layered structure built from VO5 pyramids, in which the layers are separated by Na(+), K(+), and H2O. The topology structure of magnetic V(4+) ions shows a quite interesting 1/5-depleted square lattice, which is quite similar to that of a famous low-dimensional quantum spin system CaV4O9. A structural and magnetic comparison confirmed that the title compound may exhibit a more pronounced 2D character with a large spin gap. PMID:26892907

  12. Single-Crystalline Hyperbranched Nanostructure of Iron Hydroxyl Phosphate Fe5(PO4)4(OH)3·2H2O for Highly Selective Capture of Phosphopeptides

    PubMed Central

    Chen, Qun; Wei, Chengzhen; Zhang, Yizhou; Pang, Huan; Lu, Qingyi; Gao, Feng

    2014-01-01

    Single-crystalline hyperbranched nanostructures of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O (giniite) with orthorhombic phase were synthesized through a simple route. They have a well-defined dendrite fractal structure with a pronounced trunk and highly ordered branches. The toxicity test shows that the hyperbranched nanostructures have good biocompatibility and low toxicity level, which makes them have application potentials in life science. The study herein demonstrated that the obtained hyperbranched giniite nanostructures show highly selective capture of phosphopeptides and could be used as a kind of promising nanomaterial for the specific capture of phosphopeptides from complex tryptic digests with the detection of MALDI-TOF mass spectrometry. PMID:24435094

  13. Key insights into the reacting kinetics of atmospheric pressure plasmas using He +N2 /O2 /CO2 /H2 O/Air mixtures

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki

    2015-09-01

    A zero dimensional kinetic chemistry computational modeling to identify the important collisional mechanisms and the dominant species in atmospheric pressure plasmas has been developed. This modeling provides an enhanced capability to tailor wide variety of reactive intermediates/species in atmospheric pressure plasmas using He +N2 /O2 /CO2 /H2 O/Air mixtures. The influence of the gas constituent, the gas temperature and the excitation frequency (kHz-, RF-, Pulsed-working) on the complex reacting chemical kinetics is clarified. This work also focuses on the benchmarking between the predictive outputs of this computer-based simulations and the diverse experimental diagnostics with particular emphasis on reactive oxygen/nitrogen intermediates/species. This work was partly supported by KAKENHI Grant Number 24561054.

  14. Vibrational spectroscopic characterization of the sulphate mineral leightonite K2Ca2Cu(SO4)4ṡ2H2O - Implications for the molecular structure

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Xi, Yunfei; Scholz, Ricardo; Graça, Leonardo Martins; Lagoeiro, Leonardo

    2013-08-01

    The mineral leightonite, a rare sulphate mineral of formula K2Ca2Cu(SO4)4ṡ2H2O, has been studied using a combination of electron probe and vibrational spectroscopy. The mineral is characterized by an intense Raman band at 991 cm-1 attributed to the SO42- ν1 symmetric stretching mode. A series of Raman bands at 1047, 1120, 1137, 1163 and 1177 cm-1 assigned to the SO42- ν3 antisymmetric stretching modes. The observation of multiple bands shows that the symmetry of the sulphate anion is reduced. Multiple Raman and infrared bands in the OH stretching region shows that water in the structure of leightonite is in a range of molecular environments.

  15. Ultrasound assisted synthesis of {[Cu2(BDC)2(dabco)].2DMF.2H2O} nanostructures in the presence of modulator; new precursor to prepare nano copper oxides.

    PubMed

    Alavi, Mohammad Amin; Morsali, Ali

    2014-03-01

    As a new precursor to prepare nano copper oxide, nanostructures of porous metal organic framework (MOF) {[Cu2(BDC)2(dabco)].2DMF.2H2O} (1) have been synthesized in the presence of acetic acid as a modulator via sonochemical method. Different concentrations of metal ion, organic linkers, modulator reagent and also different sonication times were held to improve the quality of nanostructures. Ultrasound irradiation helps nucleation step of the oriented attachment of modulation method and nanoparticles with a few nanorods has been prepared. As prepared MOF was calcinated at 500 °C to prepare nano CuO and Cu2O. Compound 1, CuO and Cu2O nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). PMID:24144482

  16. Hydration Enthalpies of Ba(2+)(H2O)x, x = 1-8: A Threshold Collision-Induced Dissociation and Computational Investigation.

    PubMed

    Wheeler, Oscar W; Carl, Damon R; Hofstetter, Theresa E; Armentrout, P B

    2015-04-23

    The sequential bond dissociation energies (BDEs) of Ba(2+)(H2O)x complexes, where x = 1-8, are determined using threshold collision-induced dissociation (TCID) in a guided ion beam tandem mass spectrometer. The electrospray ionization source generates complexes ranging in size from x = 6 to x = 8 with smaller complexes, x = 1-5, formed by an in-source fragmentation technique. The only products observed result from sequential loss of water ligands. Charge separation, a process in which both hydrated singly charged barium hydroxide and hydronium ion are formed, was not observed except for Ba(2+)(H2O)3 yielding BaOH(+) + H5O2(+). Modeling of the kinetic energy-dependent cross sections, taking into account the number of collisions, energy distributions, and lifetime effects for both primary and secondary water loss, provides 0 K BDEs. Experimental thermochemistry for the x = 1-3 complexes is obtained here for the first time. Hydration enthalpies and reaction coordinate pathways for charge separation are also examined computationally at several levels of theory. Our experimental and computational work are in excellent agreement in the x = 1-6 range. The present experimental values and theoretical calculations are also in reasonable agreement with the available literature values for experiment, x = 4-8, and theory, x = 1-6. Of the numerous calculations performed in the current study, B3LYP/DHF/def2-TZVPP calculations including counterpoise corrections reproduce our experimental values the best, although MP2(full)/DHF/def2-TZVPP//B3LYP/DHF/def2-TZVPP results are comparable. PMID:25822138

  17. Influence of operational key parameters on the photocatalytic decolorization of Rhodamine B dye using Fe2+/H2O2/Nb2O5/UV system.

    PubMed

    Hashemzadeh, Fatemeh; Rahimi, Rahmatollah; Gaffarinejad, Ali

    2014-04-01

    The present research deals with the development of a new heterogeneous photocatalysis and Fenton hybrid system for the removal of color from textile dyeing wastewater as Rhodamine B (RhB) solutions by using Fe(2+)/H2O2/Nb2O5 as a photocatalytic system. The application of this photocatalytic system for the decolorization of dye contaminants is not reported in the literature yet. Different parameters like dye concentration, Nb2O5/Fe(2+) catalyst amount, pH, and H2O2 concentration have been studied. The optimum conditions for the decolorization of the dye were initial concentration of 10 mg L(-1) of dye, pH 4, and Nb2O5/Fe(2+) catalyst concentration of 0.5 g L(-1)/50 mg L(-1). The optimum value of H2O2 concentration for the conditions used in this study was 700 mg L(-1). Moreover, the efficiency of the Nb2O5/photo-Fenton hybrid process in comparison to photo-Fenton alone and a dark Fenton process as a control experiment to decolorize the RhB solution has been investigated. The combination of photo-Fenton and Nb2O5 catalysts has been proved to be the most effective for the treatment of such type of wastewaters. The results revealed that the RhB dye was decolorized in a higher percent (78 %) by the Nb2O5/photo-Fenton hybrid process (Fe(2+)/H2O2/Nb2O5/UV) than by the photo-Fenton process alone (37 %) and dark Fenton process (14 %) after 120 min of treatment. Moreover, the Nb2O5 catalyst as a heterogeneous part of the photocatalytic system was demonstrated to have good stability and reusability. PMID:24374619

  18. Hydrated copper ion chemistry: guided ion beam and computational investigation of Cu2+(H2O)n (n = 7-10) complexes.

    PubMed

    Armentrout, Peter B; Sweeney, Andrew F

    2015-01-01

    Cross sections for the threshold collision-induced dissociation of Cu(2+)(H(2)O)(n), where n = 8 - 10, are measured using a guided ion beam tandem mass spectrometer. The primary dissociation pathway is found to be loss of a single water molecule followed by the sequential loss of additional water molecules until n = 8, at which point charge separation to form CuOH(+)(H(2)O)(4) (+) H(+)(H(2)O)(3) is observed to occur at a slightly lower energy than loss of a water molecule. Competition from charge separation prohibits the formation of appreciable amounts of the n = 7 or smaller complexes as reactants in the source. These findings indicate that Cu(2+) has a critical size of 8. Analysis of the data using statistical modeling techniques that account for energy distributions and lifetime effects yields primary and sequential bond dissociation energies (BDEs) for loss of one and two water molecules from n = 8 - 10 complexes as well as the barrier for charge separation from n = 8. More speculative analysis extends the thermochemistry obtained down to n = 5 and 6. Theoretical BDEs are determined from quantum chemical calculations using structures optimized at the B3LYP/6 311(+)G(d,p) level along with the lowest-energy isomers suggested by single point energies at the MP2(full), M06, B3LYP, and B3P86 levels of theory using a 6- 311(+)G(2d,2p) basis set. BDEs at 0K are converted to 298 K thermodynamic values using a rigid rotor/harmonic oscillator approximation. Experimental and theoretical entropies of activation suggest that a third solvent shell forms at n = 9, in accord with previous findings. The present work represents the first experimentally determined hydration enthalpies for the Cu(2+)(H(2)O)n system. PMID:26307731

  19. Oxidation of disinfectants with Cl-substituted structure by a Fenton-like system Cu(2+)/H2O2 and analysis on their structure-reactivity relationship.

    PubMed

    Peng, Jianbiao; Li, Jianhua; Shi, Huanhuan; Wang, Zunyao; Gao, Shixiang

    2016-01-01

    As widely used chemicals intended to protect human being from infection of microorganisms, disinfectants are ubiquitous in the environment. Among them chlorine-substituted phenol is a basic structure in many disinfectant molecules. Removal of these pollutants from wastewater is of great concern. The oxidative degradation of antimicrobial agents such as triclosan, chlorofene, and dichlorofene by a Fenton-like system Cu(2+)/H2O2 was examined. Reaction conditions such as temperature, initial concentrations of H2O2 and Cu(2+), and pH were optimized using triclosan as a representative. The degradation kinetics of the above disinfectants followed pseudo-first-order kinetics under the investigated conditions. Fourteen chlorophenols (CPs) with different chlorine substitution were also studied to evaluate the influence of molecular structure on the degradation process in the Cu(2+)/H2O2 system. Fourteen structure-related parameters were calculated using Gaussian 09 program. A quantitative structure-activity relationship (QSAR) model was established using SPSS software with measured rate constant (k) as dependent variable and calculated molecular descriptors as independent variables. A three-parameter model including energy of HOMO (E homo), molar heat capacity at constant volume (Cv(θ)), and the most positive net charge of hydrogen atoms (qH(+)) was selected for k prediction, with correlation coefficient R(2) = 0.878. Analyses of the model demonstrated that the Cv(θ) was the most significant factor affecting the k of chlorophenols. Variance analysis and standard t-value test were used to validate the model. PMID:26408114

  20. Thermal decomposition of [Co(en)3][Fe(CN)6]∙ 2H2O: Topotactic dehydration process, valence and spin exchange mechanism elucidation

    PubMed Central

    2013-01-01

    Background The Prussian blue analogues represent well-known and extensively studied group of coordination species which has many remarkable applications due to their ion-exchange, electron transfer or magnetic properties. Among them, Co-Fe Prussian blue analogues have been extensively studied due to the photoinduced magnetization. Surprisingly, their suitability as precursors for solid-state synthesis of magnetic nanoparticles is almost unexplored. In this paper, the mechanism of thermal decomposition of [Co(en)3][Fe(CN)6] ∙∙ 2H2O (1a) is elucidated, including the topotactic dehydration, valence and spins exchange mechanisms suggestion and the formation of a mixture of CoFe2O4-Co3O4 (3:1) as final products of thermal degradation. Results The course of thermal decomposition of 1a in air atmosphere up to 600°C was monitored by TG/DSC techniques, 57Fe Mössbauer and IR spectroscopy. As first, the topotactic dehydration of 1a to the hemihydrate [Co(en)3][Fe(CN)6] ∙∙ 1/2H2O (1b) occurred with preserving the single-crystal character as was confirmed by the X-ray diffraction analysis. The consequent thermal decomposition proceeded in further four stages including intermediates varying in valence and spin states of both transition metal ions in their structures, i.e. [FeII(en)2(μ-NC)CoIII(CN)4], FeIII(NH2CH2CH3)2(μ-NC)2CoII(CN)3] and FeIII[CoII(CN)5], which were suggested mainly from 57Fe Mössbauer, IR spectral and elemental analyses data. Thermal decomposition was completed at 400°C when superparamagnetic phases of CoFe2O4 and Co3O4 in the molar ratio of 3:1 were formed. During further temperature increase (450 and 600°C), the ongoing crystallization process gave a new ferromagnetic phase attributed to the CoFe2O4-Co3O4 nanocomposite particles. Their formation was confirmed by XRD and TEM analyses. In-field (5 K / 5 T) Mössbauer spectrum revealed canting of Fe(III) spin in almost fully inverse spinel structure of CoFe2O4. Conclusions It has been found

  1. Analysis of Heterogeneity in CO2, H2O and OH in Centimeter-Sized Obsidian Pyroclasts from Mono Craters, California

    NASA Astrophysics Data System (ADS)

    Conde, G. D.; Watkins, J. M.

    2014-12-01

    Volcanic tephra deposits typically contain inclusions or fragments of quenched melt that preserve pre-eruptive volatile concentrations within the volcanic conduit. The concentrations of CO2, H2O and OH in obsidian pyroclasts provide information on magma storage depths while gradients in these volatile species provide information on rates and mechanisms of gas loss (or gain) in magma during ascent. We are measuring CO2, H2O and OH profiles and area maps in six randomly selected pyroclastic obsidian clasts from Mono Craters, California using conventional Fourier Transform Infrared Spectroscopy (FTIR). Previous studies of these pyroclasts have focused on spot analyses of volatile concentrations within clast interiors, but our study targets clast rims, bubbles, flow bands, and texturally homogeneous regions of the clasts. The objective is to use the magnitude and spatial distribution of heterogeneities to assess the role of vapor fluxing and to determine timescales of magmatic processes such as bubble growth/resorption and mixing of magma from variable depths. The first clast that we have analyzed is relatively homogeneous in dissolved H2O and OH but exhibits millimeter-scale heterogeneities in dissolved CO2. The concentration of dissolved CO2 varies by a factor of two, ranging from 15 to 30 ppm with a patchy distribution throughout the clast. The patches of high CO2 concentration do not correspond to visible textures within the clast. Total water (H2Ot) varies from 1.5 to 1.7 wt% with higher water concentrations corresponding to darker regions of glass. The distribution of CO2 requires a mechanism for introducing millimeter-scale heterogeneity within minutes to hours prior to the eruption. Our interpretation is that obsidian pyroclasts are assembled during chaotic vertical mixing and thus sample a range of depths within the feeder system. This interpretation is consistent with previous inferences that resorption of bubbles within pyroclasts is caused by repeated

  2. A SAFT Equation of State for the Quaternary H2S-CO2-H2O-NaCl system

    NASA Astrophysics Data System (ADS)

    Ji, X.; Zhu, C.

    2011-12-01

    Phase equilibria and thermodynamic properties of the quaternary H2S-CO2-H2O-NaCl system were studied using a statistical associating fluid theory (SAFT)-based equation of state (EOS). The understanding of the physical-chemical properties of this system is critical for predicting the consequences of co-injection of CO2 and H2S into geological formations (geological carbon sequestration) as an option for mitigating the global warming trend. Previous studies of the subsystems within this quaternary have provided many parameters for the EOS. In this study, the subsystems of H2S-CO2 and H2S-H2O-NaCl were investigated in order to obtain the cross parameters for the EOS. For the binary system H2S-CO2, cross association between the site H in H2S and the site O in CO2 was allowed and temperature-independent parameters were used to describe this cross association. Meanwhile, a temperature-dependent binary interaction parameter was used to adjust the cross dispersive energy for this binary system. For the H2S-H2O-NaCl system, one temperature-dependent cross parameter was allowed in order to adjust the cross dispersive energy between H2S and ions of Na+ and Cl-. All cross parameters were fitted to the reliable phase equilibrium experimental data. Densities were predicted and compared with available experimental results. Using the EOS developed in this study, we predicted equilibrium composition in both liquid and vapor phases, the equilibrium pressures at a given composition of the H2O-rich phase in electrolyte solutions with NaCl varying from 0 to 4 mol/kgH2O, and the aqueous solution densities. These predictions provide information and guidance for future experiments regarding the thermodynamic properties and phase behaviors in the H2S-CO2-H2O-NaCl system.

  3. EPR, Endor and DFT Studies on X-Irradiated Single Crystals of L-Lysine HCl 2 H 2O and L-Arginine HCl H2O

    NASA Astrophysics Data System (ADS)

    Zhou, Yiying; Nelson, William H.

    2011-03-01

    When proteins and DNA interact, arginine and lysine are the two amino acids most often in close contact with the DNA. In order to understand the radiation damage to DNA in vivo, which is always associated with protein, it is important to learn the radiation chemistry of arginine and lysine independently, and then complexed to DNA. This work studied X-irradiated single crystals of L- lysine . HCl . 2 H2 O and L- arginine . HCl . H2 O with EPR, ENDOR techniques and DFT calculations. In both crystal types irradiated at 66K, the carboxyl anion radical and the decarboxylation radical were identified. Specifically, the calculations performed on the cluster models for the carboxyl anion radicals reproduced the proton transfers to the carboxyl group from the neighboring molecules through the hydrogen bonds. Moreover, computations supported the identification of one radical type within irradiated arginine as the guanidyl radical anion with an electron trapped by the guanidyl group. Based on the radicals detected in the crystal irradiated at 66K and at 298K, and the annealing experiments from the irradiation at 66K, the mechanisms of the irradiation damage on lysine and arginine were proposed, and the possible effects of irradiated arginine and lysine to the DNA within chromatin were analyzed.

  4. A Raman spectroscopic study of the antimonite mineral peretaite Ca(SbO) 4(OH) 2(SO 4) 2·2H 2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Keeffe, Eloise C.; Bahfenne, Silmarilly

    2010-05-01

    Raman spectra of mineral peretaite Ca(SbO) 4(OH) 2(SO 4) 2·2H 2O were studied, and related to the structure of the mineral. Raman bands observed at 978 and 980 cm -1 and a series of overlapping bands observed at 1060, 1092, 1115, 1142 and 1152 cm -1 are assigned to the SO 42-ν1 symmetric and ν3 antisymmetric stretching modes. Raman bands at 589 and 595 cm -1 are attributed to the SbO symmetric stretching vibrations. The low intensity Raman bands at 650 and 710 cm -1 may be attributed to SbO antisymmetric stretching modes. Raman bands at 610 cm -1 and at 417, 434 and 482 cm -1 are assigned to the SO 42-ν4 and ν2 bending modes, respectively. Raman bands at 337 and 373 cm -1 are assigned to O-Sb-O bending modes. Multiple Raman bands for both SO 42- and SbO stretching vibrations support the concept of the non-equivalence of these units in the peretaite structure.

  5. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    PubMed Central

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-01-01

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. PMID:24957062

  6. Re-oxidation Kinetics of Flash-Reduced Iron Particles in H2-H2O(g) Atmosphere Relevant to a Novel Flash Ironmaking Process

    NASA Astrophysics Data System (ADS)

    Yuan, Zhixue; Sohn, Hong Yong; Olivas-Martinez, Miguel

    2013-12-01

    A novel flash ironmaking process based on hydrogen-containing reduction gases is under development at the University of Utah. The goal of this work was to study the possibility of the re-oxidation of iron particles in a H2-H2O gas mixture in the lower part of the flash reactor from the kinetic point of view. The last stage of hydrogen reduction of iron oxide, i.e., the reduction of wustite, is limited by equilibrium. As the reaction mixture cools down, the re-oxidation of iron could take place because of the decreasing equilibrium constant and the high reactivity of the freshly reduced fine iron particles. The effects of temperature and H2O partial pressure on the re-oxidation rate were examined in the temperature range of 823 K to 973 K (550 °C to 700 °C) and H2O contents of 40 to 100 pct. The nucleation and growth kinetics model was shown to best describe the re-oxidation kinetics. The partial pressure dependence with respect to water vapor was determined to be of first order, and the activation energy of re-oxidation reaction was 146 kJ/mol. A complete rate equation that adequately represents the experimental data was developed.

  7. Corrosion of 310 stainless steel in H2-H2O-H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Jacob, K. T.; Nelson, H. G.

    1981-01-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 x 10 to the minus 13th power/cu Nm and sulfur potentials ranging from 0.19 x 10 to the minus 2nd power/cu Nm to 33 x 10 to the minus 2nd power/cu Nm. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials (p sub S sub 2 less than or equal to 2.7 x 10 to the minus 2nd power/cu Nm) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfication. At low sulfur potentials (P sub S sub 2 less than or equal to 0.19 x 10 to the minus 2nd power/cu Nm) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases.

  8. Pressure-induced magnetic crossover driven by hydrogen bonding in CuF2(H2O)2(3-chloropyridine)

    DOE PAGESBeta

    O'Neal, Kenneth R.; Brinzari, Tatiana V.; Wright, Joshua B.; Ma, Chunli; Giri, Santanab; Schlueter, John A.; Wang, Qian; Jena, Puru; Liu, Zhenxian; Musfeldt, Janice L.

    2014-08-13

    Here, hydrogen bonding plays a foundational role in the life, earth, and chemical sciences, with its richness and strength depending on the situation. In molecular materials, these interactions determine assembly mechanisms, control superconductivity, and even permit magnetic exchange. In spite of its long-standing importance, exquisite control of hydrogen bonding in molecule-based magnets has only been realized in limited form and remains as one of the major challenges. Here, we report the discovery that pressure can tune the dimensionality of hydrogen bonding networks in CuF2(H2O)2(3-chloropyridine) to induce magnetic switching. Specifically, we reveal how the development of exchange pathways under compression combinedmore » with an enhanced ab-plane hydrogen bonding network yields a three dimensional superexchange web between copper centers that triggers a reversible magnetic crossover. Similar pressure- and strain-driven crossover mechanisms involving coordinated motion of hydrogen bond networks may play out in other quantum magnets.« less

  9. Crystal structure and luminescence property of novel three-dimensional network of {Eu 2( p-BDC) 3(Phen) 2(H 2O) 2} n

    NASA Astrophysics Data System (ADS)

    Wang, M.; Xia, J.; Jin, L.; Cai, G.; Lu, S.

    2003-08-01

    The single crystal of a supramolecule, {Eu 2( p-BDC) 3(Phen) 2(H 2O) 2} n ( p-BDC=1,4-benzenedicarboxylate), with characteristic luminescence of Eu 3+ was obtained by means of soft chemistry. The crystal structure determination reveals that each Eu 3+ ion is coordinated by five oxygen atoms of p-BDC anions, one oxygen atom from water molecule, and two nitrogen atoms of Phen, respectively, resulting in an eight-coordinated Eu 3+ center and a distorted square antiprism coordination polyhedron. Four bridges, two carboxylates of μ 4- p-BDC and two of μ 3- p-BDC, connect two Eu atoms into a binuclear unit. Moreover, the μ 3- p-BDC integrates the binuclear building blocks at the direction of b axis and the μ 4- p-BDC polymerizes the structure roughly along the direction of the sum vector of axis b and c, respectively, forming two-dimensional layers. Hydrogen bonds between layers make the structure a three-dimensional network. The luminescence spectra measured under 77 K demonstrate the antenna effect of Phen and the 5D 1→ 5D 0 energy transfer path within Eu 3+ ion. Both luminescence spectra and crystal structure lead to the conclusion that the local symmetry around the Eu 3+ ion is C1 and that more than one Eu 3+ ion sites having slight environmental difference are present.

  10. A vibrational spectroscopic study of the silicate mineral analcime - Na2(Al4SiO4O12)·2H2O - a natural zeolite.

    PubMed

    Frost, Ray L; López, Andrés; Theiss, Frederick L; Romano, Antônio Wilson; Scholz, Ricardo

    2014-12-10

    We have studied the mineral analcime using a combination of scanning electron microscopy with energy dispersive spectroscopy and vibrational spectroscopy. The mineral analcime Na2(Al4SiO4O12)·2H2O is a crystalline sodium silicate. Chemical analysis shows the mineral contains a range of elements including Na, Al, Fe(2+) and Si. The mineral is characterized by intense Raman bands observed at 1052, 1096 and 1125cm(-1). The infrared bands are broad; nevertheless bands may be resolved at 1006 and 1119cm(-1). These bands are assigned to SiO stretching vibrational modes. Intense Raman band at 484cm(-1) is attributed to OSiO bending modes. Raman bands observed at 2501, 3542, 3558 and 3600cm(-1) are assigned to the stretching vibrations of water. Low intensity infrared bands are noted at 3373, 3529 and 3608cm(-1). The observation of multiple water bands indicate that water is involved in the structure of analcime with differing hydrogen bond strengths. This concept is supported by the number of bands in the water bending region. Vibrational spectroscopy assists with the characterization of the mineral analcime. PMID:24983920

  11. Solid-liquid equilibria in the NaCl-SrCl2-H2O system at 288.15 K

    NASA Astrophysics Data System (ADS)

    Li, Dan; Meng, Qing-fen; Meng, Ling-zong; Fan, Xiu-xiu

    2016-02-01

    The phase equilibria in the ternary system NaCl-SrCl2-H2O at 288.15 K were studied with the isothermal equilibrium solution method. The phase diagram and refractive index diagram were plotted for this system at 288.15 K. The phase diagram contains one invariant solubility point, two univariant solubility curves, and two crystallization fields of NaCl and SrCl2 · 6H2O. The refractive indices of the equilibrium solution change regularly with w(NaCl) increase. The calculated refractive index data are in good agreement with the experimental data. Combining the experimental solubility data of the ternary system, the Pitzer binary parameters for NaCl at 288.15 K and SrCl2 at 298.15 K, the Pitzer mixing parameters θNa, Sr, ΨNa, Sr, Cl and the solubility equilibrium constants Ksp of solid phases existing in the ternary system at 288.15 K were fitted using the Pitzer and Harvie-Weare (HW) models. The mean activity coefficients of sodium chloride and strontium chloride, and the solubilities for the ternary system at 288.15 K were presented. A comparison between the calculated and measured solubilities shows that the predicted data agree well with the experimental results.

  12. Reactivity of a thick BaO film supported on Pt(111): adsorption and reaction of NO2, H2O, and CO2.

    PubMed

    Mudiyanselage, Kumudu; Yi, Cheol-Woo; Szanyi, János

    2009-09-15

    Reactions of NO2, H2O, and CO2 with a thick (>20 monolayer equivalent (MLE)) BaO film supported on Pt(111) were studied with temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). NO2 reacts with a thick BaO layer to form surface nitrite-nitrate ion pairs at 300 K, while only nitrates form at 600 K. In the thermal decomposition process of nitrite-nitrate ion pairs, first nitrites decompose and desorb as NO. Then nitrates decompose in two steps: at lower temperature with the release of NO2 and at higher temperature, nitrates dissociate to NO+O2. The thick BaO layer converts completely to Ba(OH)2 following the adsorption of H2O at 300 K. Dehydration/dehydroxylation of this hydroxide layer can be fully achieved by annealing to 550 K. CO2 also reacts with BaO to form BaCO3 that completely decomposes to regenerate BaO upon annealing to 825 K. However, the thick BaO film cannot be converted completely to Ba(NOx)2 or BaCO3 under the experimental conditions employed in this study. PMID:19588918

  13. Reactivity of a Thick BaO Film Supported on Pt(111): Adsorption and Reaction of NO2, H2O and CO2

    SciTech Connect

    Mudiyanselage, Kumudu; Yi, Cheol-Woo W.; Szanyi, Janos

    2009-09-15

    Reactions of NO2, H2O, and CO2 with a thick (> 20 MLE) BaO film supported on Pt(111) were studied with temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). NO2 reacts with a thick BaO to form surface nitrite-nitrate ion pairs at 300 K, while only nitrates form at 600 K. In the thermal decomposition process of nitrite–nitrate ion pairs, first nitrites decompose and desorb as NO. Then nitrates decompose in two steps : at lower temperature with the release of NO2 and at higher temperature, nitrates dissociate to NO + O2. The thick BaO layer converts completely to Ba(OH)2 following the adsorption of H2O at 300 K. Dehydration/dehydroxylation of this hydroxide layer can be fully achieved by annealing to 550 K. CO2 also reacts with BaO to form BaCO3 that completely decomposes to regenerate BaO upon annealing to 825 K. However, the thick BaO film cannot be converted completely to Ba(NOx)2 or BaCO3 under the experimental conditions employed in this study.

  14. Redetermination of ruizite, Ca2Mn3+ 2[Si4O11(OH)2](OH)2·2H2O

    PubMed Central

    Fendrich, Kim V.; Downs, Robert T.; Origlieri, Marcus J.

    2016-01-01

    The crystal structure of ruizite, ideally Ca2Mn3+ 2[Si4O11(OH)2](OH)2·2H2O [dicalcium dimanganese(III) tetra­silicate tetra­hydroxide dihydrate] was first determined in space group A2 with an isotropic displacement parameter model (R = 5.6%) [Hawthorne (1984 ▸). Tschermaks Mineral. Petrogr. Mitt. 33, 135–146]. A subsequent refinement in space group C2/m with anisotropic displacement parameters for non-H atoms converged with R = 8.4% [Moore et al. (1985 ▸). Am. Mineral. 70, 171–181]. The current study reports a redetermination of the ruizite structure by means of single-crystal X-ray diffraction data of a natural sample from the Wessels mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Our data (R 1 = 3.0%) confirm that the space group of ruizite is that of the first study rather than C2/m. This work improves upon the structure reported by Hawthorne (1984 ▸) in that all non-H atoms were refined with anisotropic displacement parameters and all hydrogen atoms were located. The crystal structure consists of [010] chains of edge-sharing MnO6 octa­hedra flanked by finite [Si4O11(OH)2] chains. The Ca2+ cations are situated in the cavities of this arrangement and exhibit a coordination number of seven. PMID:27555940

  15. EPR, ENDOR and DFT study of L-lysine·HCl·2H 2O single crystals X-irradiated at 66 K

    NASA Astrophysics Data System (ADS)

    Zhou, Yiying; Nelson, William H.

    2010-04-01

    Electron Paramagnetic Resonance (EPR), Electron-Nuclear DOuble Resonance (ENDOR) and ENDOR-Induced EPR (EIE) results indicated at least three radicals produced in L-lysine·HCl·2H 2O crystals irradiated at 66 K. EPR from radical R1 dominated the spectra and it was identified as the carboxyl anion, (H 2OOĊ) CH (NH 3) + (CH 2) 4 (NH 3) +. Density-Functional Theory (DFT) calculations supported the assignment and indicated that the carboxyl group transformed from planar to a pyramidal configuration following electron trapping. Two small couplings detected from R1 were ascribed to protons transferred to the carboxyl group from neighboring molecules through intermolecular hydrogen bonds. Radical R2 was identified as the product of decarboxylation, ĊH (NH 3) +(CH 2) 4 (NH 3) +. Although it was not possible to obtain R2's α-coupling tensor from the experiment, EPR simulations and DFT calculations provided strong support for the identification. Radical R3 exhibited several β-couplings but could be detected only in one plane and could not be identified.

  16. A vibrational spectroscopic study of the silicate mineral analcime - Na2(Al4SiO4O12)·2H2O - A natural zeolite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Theiss, Frederick L.; Romano, Antônio Wilson; Scholz, Ricardo

    2014-12-01

    We have studied the mineral analcime using a combination of scanning electron microscopy with energy dispersive spectroscopy and vibrational spectroscopy. The mineral analcime Na2(Al4SiO4O12)·2H2O is a crystalline sodium silicate. Chemical analysis shows the mineral contains a range of elements including Na, Al, Fe2+ and Si. The mineral is characterized by intense Raman bands observed at 1052, 1096 and 1125 cm-1. The infrared bands are broad; nevertheless bands may be resolved at 1006 and 1119 cm-1. These bands are assigned to SiO stretching vibrational modes. Intense Raman band at 484 cm-1 is attributed to OSiO bending modes. Raman bands observed at 2501, 3542, 3558 and 3600 cm-1 are assigned to the stretching vibrations of water. Low intensity infrared bands are noted at 3373, 3529 and 3608 cm-1. The observation of multiple water bands indicate that water is involved in the structure of analcime with differing hydrogen bond strengths. This concept is supported by the number of bands in the water bending region. Vibrational spectroscopy assists with the characterization of the mineral analcime.

  17. An investigation on the structure, spectroscopy and thermodynamic aspects of Br2((-))(H2O)n clusters using a conjunction of stochastic and quantum chemical methods.

    PubMed

    Naskar, Pulak; Chaudhury, Pinaki

    2016-06-28

    In this work we obtained global as well as local structures of Br2((-))(H2O)n clusters for n = 2 to 6 followed by the study of IR-spectral features and thermochemistry for the structures. The way adopted by us to obtain structures is not the conventional one used in most cases. Here we at first generated excellent quality pre-optimized structures by exploring the suitable empirical potential energy surface using stochastic optimizer simulated annealing. These structures are then further refined using quantum chemical calculations to obtain the final structures, and spectral and thermodynamic features. We clearly showed that our approach results in very quick and better convergence which reduces the computational cost and obviously using the strategy we are able to get one [i.e. global] or more than one [i.e. global and local(s)] energetically lower structures than those which are already reported for a given cluster size. Moreover, IR-spectral results and the evolutionary trends in interaction energy, solvation energy and vertical detachment energy for global structures of each size have also been presented to establish the utility of the procedure employed. PMID:27251059

  18. Composition dependent behavior in the ternary mixed magnetic insulator Co1-xMnyNix-yCl2·2H2O

    NASA Astrophysics Data System (ADS)

    DeFotis, G. C.; Hampton, A. S.; Wallin, T. J.; Trowell, K. T.; Pothen, J. M.; Welshhans, E. A.; Havas, K. C.

    2016-05-01

    The properties of ternary mixed magnetic Co1-xMnyNix-yCl2·2H2O are examined by dc magnetization and susceptibility measurements, from 1.8 to 300 K as a function of composition. This is only the second ternary magnetic insulator so studied. The three transition metal chloride dihydrate components are known to differ in the degree of spin anisotropy and in the distribution of ferromagnetic and antiferromagnetic exchange interactions within and between strongly coupled chemical and structural chains. The Curie and Weiss constants, in χM=C/(T-θ) fits to high temperature susceptibilities, are compared with weighted averages of pure component values. The observed Weiss constant is almost uniformly less negative than calculated. Maxima in low temperature susceptibilities vary widely in presence and location with composition. Some compositions exhibit no susceptibility maximum, many exhibit one maximum, and three exhibit two maxima. A T(x,y) diagram is constructed. Magnetization vs field isotherms exhibit different shapes as a function of composition, with hysteresis markedly composition dependent. For three mixtures hysteresis loops are studied as a function of temperature. An activation process model does not describe the temperature dependence well.

  19. Quantum mechanical reaction rate constants by vibrational configuration interaction: the OH + H2->H2O + H reaction as a function of temperature.

    PubMed

    Chakraborty, Arindam; Truhlar, Donald G

    2005-05-10

    The thermal rate constant of the 3D OH + H(2)-->H(2)O + H reaction was computed by using the flux autocorrelation function, with a time-independent square-integrable basis set. Two modes that actively participate in bond making and bond breaking were treated by using 2D distributed Gaussian functions, and the remaining (nonreactive) modes were treated by using harmonic oscillator functions. The finite-basis eigenvalues and eigenvectors of the Hamiltonian were obtained by solving the resulting generalized eigenvalue equation, and the flux autocorrelation function for a dividing surface optimized in reduced-dimensionality calculations was represented in the basis formed by the eigenvectors of the Hamiltonian. The rate constant was obtained by integrating the flux autocorrelation function. The choice of the final time to which the integration is carried was determined by a plateau criterion. The potential energy surface was from Wu, Schatz, Lendvay, Fang, and Harding (WSLFH). We also studied the collinear H + H(2) reaction by using the Liu-Siegbahn-Truhlar-Horowitz (LSTH) potential energy surface. The calculated thermal rate constant results were compared with reported values on the same surfaces. The success of these calculations demonstrates that time-independent vibrational configuration interaction can be a very convenient way to calculate converged quantum mechanical rate constants, and it opens the possibility of calculating converged rate constants for much larger reactions than have been treated until now. PMID:15774583

  20. Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate, an inorganic analogue of phosphonates

    NASA Astrophysics Data System (ADS)

    Belokoneva, E. L.; Dimitrova, O. V.; Volkov, A. S.

    2015-09-01

    The new Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate (space group Pnam = Pnma, D {2/h 16}) is obtained under hydrothermal conditions. The crystal structure is determined without preliminary knowledge of the chemical formula. The structure consists of layers of MnО6 octahedra connected with PO4 tetrahedra. Water molecules are located between the layers. [IO3]- groups having a typical umbrella-like coordination are statistically implanted in layers of MnО6 octahedra at a distance of 1.2 Å from Mn atoms. Their content in the crystal is minor. The structures of the phosphate-iodate coincides with the structures of phosphonates with consideration for the replacement of one (OH) vertex of the РО4 tetrahedron by the organic methyl radical СН3. In the structures of phosphonates and earlier studied phosphates, identical layers are distinguished and the cause of the existence of two MDO varieties is established based on the analysis within the OD theory. Possible hybrid structures derived from the prototypes under consideration are predicted.

  1. A novel quaternary dinuclear luminescent terbium complex Tb 2(phth) 2(Hphth) 2(phen) 2(H 2O) 4: hydrothermal synthesis, crystal structure and photophysics

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Song, Yi-Shan; Chen, Zhen-Xia

    2004-06-01

    Assembling potassium acid phthalate (KHphth), 1,10-phenanthroline (phen) and terbium nitrate, a novel quaternary dinuclear terbium complex with formula Tb 2(phth) 2(Hphth) 2(phen) 2(H 2O) 4 (H 2phth=phthalic acid, phen=1,10-phenanthroline) has been firstly synthesized by hydrothermal process. X-ray analysis reveals that it forms dimeric structure and the two central terbium ions have the same coordination environment. The title complex crystallizes in the triclinic system, space group P-1, with lattice parameters a=10.149(5) Å, b=10.730(5) Å, c=11.906(5) Å, α=90.427(6)°, β=99.474(6)°, γ=101.088(6)°, F(000)=696, GOF=0.931, R1=0.0308, wR2=0.0606 and Z=1. The photophysical properties have been studied with ultraviolet absorption spectrum, excitation and emission spectrum, which exhibit strong green emission.

  2. Structure and thermal behaviour of ScK(C 2O 4) 2(H 2O) 2 and InRb 1- x(H 3O) x(C 2O 4) 2(H 2O) 2ṡ0.5(H 2O): Two members of a family of open-framework oxalates with isotypic helical structures and zeolite-like properties

    NASA Astrophysics Data System (ADS)

    Mahé, Nathalie; Audebrand, Nathalie

    2006-08-01

    Two new mixed oxalates with an open architecture, ScK(C 2O 4) 2(H 2O) 2 ( I) and InRb 0.77(H 3O) 0.23(C 2O 4) 2(H 2O) 2ṡ0.5(H 2O) ( II), have been synthesised from precipitation methods at ambient temperature. They crystallize in hexagonal system, space group P622 (No. 180), Z=3, with the following unit-cell parameters for I: a=8.8667(2) Å, c=11.4908(4) Å, V=782.36(4) Å, for II: a=9.0148(3) Å, c=11.4645(3) Å, V=806.86(4) Å. The two structures belong to a family of isotypic helical anionic open-frameworks built from square antiprismatic coordinated metals and bischelating oxalates. The counter-cations K + and Rb +/H 3O + are located in the tunnels of the framework. The thermal decomposition process has demonstrated zeolite-like properties associated with weakly-bonded water molecules located in the voids of the framework.

  3. First outer-sphere 1,3-diethyl-2-thiobarbituric compounds [M(H2O)6](1,3-diethyl-2-thiobarbiturate)2·2H2O (M = Co2+, Ni2+): Crystal structure, spectroscopic and thermal properties

    NASA Astrophysics Data System (ADS)

    Golovnev, Nicolay N.; Molokeev, Maxim S.; Lesnikov, Maxim K.; Atuchin, Victor V.

    2016-06-01

    Two new d-element compounds, [Co(H2O)6](Detba)2·2H2O (1) and [Ni(H2O)6](Detba)2·2H2O (2) (HDetba - 1,3-diethyl-2-thiobarbituric acid) were synthesized and characterized by single-crystal and powder X-ray diffraction analysis, TG-DSC and FT-IR. Structural analysis revealed that (1) and (2) are discrete structures, in which M2+ ion (M = Co, Ni) is six-coordinated by water molecules and it forms an octahedron. The outer-sphere Detba- ions and H2O molecules participate in Osbnd H⋯(O/S) intermolecular hydrogen bonds which form the 2D layer. Thermal decomposition includes the stage of dehydration and the following stage of oxidation of Detba- with a release of CO2, SO2, H2O, NH3 and isocyanate gases.

  4. Prediction of phase equilibrium for the aqueous systems Rb+, Cs+/Cl-, SO{4/-}-H2O and K+, Cs+/Cl-, SO{4/2-}-H2O at 25°C

    NASA Astrophysics Data System (ADS)

    Hu, B.

    2013-05-01

    The Pitzer ion-interaction extended by Harvic and Weare was applied to predict the solubility isotherms of reciprocal quaternary systems in which mixed crystals are formed. On the basis of data concerning the binary and ternary subsystems, the four components systems Rb+, Cs+/Cl-, SO{4/2-}-H2O, and K+, Cs+/Cl-, SO{4/2-}-H2O were investigated at 25°C.The results of calculation can be used to model salt crystallization during the concentration of brines.

  5. COMBINING THE STRENGTHS OF OPEN-PATH AND CLOSED-PATH DESIGNS INTO A SINGLE CO2/H2O GAS ANALYZER

    NASA Astrophysics Data System (ADS)

    Burba, G. G.; Furtaw, M.; McDermitt, D. K.; Eckles, R.

    2009-12-01

    Open-path and closed-path designs of the fast CO2/H2O gas analyzers are widely used to measure concentrations and fluxes. Both designs have their advantages and deficiencies. Open-path analyzers have excellent frequency response, long-term stability, and low sensitivity to window contamination. They are pump-free and require infrequent calibrations. Yet they are susceptible to data loss during precipitation and icing, and may need instrument surface heat flux correction when used in cold conditions. Closed-path analyzers can collect data during precipitation, can be climate-controlled, and are not susceptible to surface heating issues. Yet they experience significant frequency loss in long intake tubes, especially problematic when computing water vapor flux. They may require frequent calibrations and need powerful pump. Here we present preliminary data from third kind of a design: a compact enclosed CO2/H2O analyzer, the LI-7200, enabled for operation with short intake tube, intended to maximize strengths and to minimize weaknesses of both traditional open-path and closed-path designs. Four prototypes were extensively field-tested in three experiments over contrasting ecosystems in 2006-2009. Instantaneous temperature fluctuations were attenuated, on average, by about 85-90% with 0.5 m intake tube, and by about 90-95% with 1 m intake tube, minimizing sensible heat flux portion of Webb-Pearman-Leuning term. The remainder was measured directly eliminating open-path heating or any other temperature issues. Fast temperature and pressure measured inside the cell of LI-7200, and low sensitivity to window contamination allowed for the use of short intake tube (0.5-1.0 m or less), leading to a low power demand for the pump and entire system. The power demand of the tested blower with flow control was about 15 W, which is considerably less than that of traditional closed-path systems (about 50-100 W). Frequency losses for CO2 and H2O fluxes from LI-7200 were small, yet

  6. Corrosion of 310 stainless steel in H2- H2O- H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Astrophysics Data System (ADS)

    Rao, D. Bhogeswara; Jacob, K. T.; Nelson, Howard G.

    1983-02-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 × 10-13 Nm-2 and sulfur potentials ranging from 0.19 × 10-2 Nm-2 to 33 × 10-2 Nm-2. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials ( P S 2 ± 2.7 × 10-2 Nm-2) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfidation. At low sulfur potentials ( P S 2 ± 0.19 × 10-2 Nm-2) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases. Thermochemical diagrams for the Fe-Cr-S-O, Fe-Ni-S-O, Cr-Ni-S-O, and Si-Cr-S-O systems were constructed, and the experimental results are discussed in relation to these diagrams. Based on this comparison, reasonable corrosion mechanisms were developed. At high sulfur potentials, oxide and sulfide phases initially nucleate as separate islands. Overgrowth of the oxide by the sulfide occurs and an exchange reaction governs the corrosion process. Preoxidation at low oxygen potentials and 1150 K is beneficial in suppressing sulfidation at high sulfur potentials.

  7. Carbon dioxide induced bubble formation in a CH4-CO2-H2O ternary system: a molecular dynamics simulation study.

    PubMed

    Sujith, K S; Ramachandran, C N

    2016-02-01

    The extraction of methane from its hydrates using carbon dioxide involves the decomposition of the hydrate resulting in a CH4-CO2-H2O ternary solution. Using classical molecular dynamics simulations, we investigate the evolution of dissolved gas molecules in the ternary system at different concentrations of CO2. Various compositions considered in the present study resemble the solution formed during the decomposition of methane hydrates at the initial stages of the extraction process. We find that the presence of CO2 aids the formation of CH4 bubbles by causing its early nucleation. Elucidation of the composition of the bubble revealed that in ternary solutions with high concentration of CO2, mixed gas bubbles composed of CO2 and CH4 are formed. To understand the role of CO2 in the nucleation of CH4 bubbles, the structure of the bubble formed was analyzed, which revealed that there is an accumulation of CO2 at the interface of the bubble and the surrounding water. The aggregation of CO2 at the bubble-water interface occurs predominantly when the concentration of CO2 is high. Radial distribution function for the CH4-CO2 pair indicates that there is an increasingly favorable direct contact between dissolved CH4 and CO2 molecules in the bubble-water interface. It is also observed that the presence of CO2 at the interface results in the decrease in surface tension. Thus, CO2 leads to greater stability of the bubble-water interface thereby bringing down the critical size of the bubble nuclei. The results suggest that a rise in concentration of CO2 helps in the removal of dissolved CH4 thereby preventing the accumulation of methane in the liquid phase. Thus, the presence of CO2 is predicted to assist the decomposition of methane hydrates in the initial stages of the replacement process. PMID:26762545

  8. Reaction Pathways and Excited States in H2O2+OH → HO2+H2O : A New ab initio Investigation

    SciTech Connect

    Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel

    2007-08-28

    The mechanism of the hydrogen abstraction reaction H2O2+OH→ HO2+H2O in gas phase was studied, using DFT (MPW1K) level of theory. We located 2 pathways for the reaction, both going through the same intermediate complex OH-H2O2, but via two distinct transition state structures that differ by the orientation of the hydroxyl hydrogen relative to the incipient hydroperoxy hydrogen. In one case, these hydrogens are on same side of the plane made by the 3 oxygen atoms and in the other these hydrogens are on opposite sides of the plane. The first two excited states were calculated for selected points of both pathways using time-dependent DFT, multiconfigurational quasi-degenerate-perturbation theory (MCQDPT2/ CASSCF) and equation of motion coupled cluster singles, doubles model (EOM-CCSD) EOMCCSD energies and completely renormalized EOM-CCSD(T)(IA) correction. An avoided crossing between the two excited states was found on both reaction pathways, on the product side of the barrier to H-transfer on the ground state surface, near the transition states. Further more, we report on the calculation of the rate of the reaction in the gas phase for temperatures in the range of 250-500 K, and suggest that the strong temperature dependence of the rate at high temperatures is due to reaction on the low-lying excited state surface over a barrier that is much larger than on the ground state surface. This work was supported in part by the Office of Basic Energy Sciences of the Department of Energy (DOE), Chemical Sciences program (BG and MD) and in part by the U.S. Department of Energy’s Office of Biological and Environmental Research, Environmental Management Science Program (BG and DMC). The Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute.

  9. Phase evolution of Na2O-Al2O3-SiO2-H2O gels in synthetic aluminosilicate binders.

    PubMed

    Walkley, Brant; San Nicolas, Rackel; Sani, Marc-Antoine; Gehman, John D; van Deventer, Jannie S J; Provis, John L

    2016-04-01

    This study demonstrates the production of stoichiometrically controlled alkali-aluminosilicate gels ('geopolymers') via alkali-activation of high-purity synthetic amorphous aluminosilicate powders. This method provides for the first time a process by which the chemistry of aluminosilicate-based cementitious materials may be accurately simulated by pure synthetic systems, allowing elucidation of physicochemical phenomena controlling alkali-aluminosilicate gel formation which has until now been impeded by the inability to isolate and control key variables. Phase evolution and nanostructural development of these materials are examined using advanced characterisation techniques, including solid state MAS NMR spectroscopy probing (29)Si, (27)Al and (23)Na nuclei. Gel stoichiometry and the reaction kinetics which control phase evolution are shown to be strongly dependent on the chemical composition of the reaction mix, while the main reaction product is a Na2O-Al2O3-SiO2-H2O type gel comprised of aluminium and silicon tetrahedra linked via oxygen bridges, with sodium taking on a charge balancing function. The alkali-aluminosilicate gels produced in this study constitute a chemically simplified model system which provides a novel research tool for the study of phase evolution and microstructural development in these systems. Novel insight of physicochemical phenomena governing geopolymer gel formation suggests that intricate control over time-dependent geopolymer physical properties can be attained through a careful precursor mix design. Chemical composition of the main N-A-S-H type gel reaction product as well as the reaction kinetics governing its formation are closely related to the Si/Al ratio of the precursor, with increased Al content leading to an increased rate of reaction and a decreased Si/Al ratio in the N-A-S-H type gel. This has significant implications for geopolymer mix design for industrial applications. PMID:26911317

  10. New zinc-glycine-iodide complexes as a product of equilibrium and non-equilibrium crystallization in the Gly - ZnI2 - H2O system

    NASA Astrophysics Data System (ADS)

    Tepavitcharova, S.; Havlíček, D.; Matulková, I.; Rabadjieva, D.; Gergulova, R.; Plocek, J.; Němec, I.; Císařová, I.

    2016-09-01

    Equilibrium crystallization of two anhydrous complex compounds, [Zn(gly)2I2] and [Zn(gly)I2], and non-equilibrium crystallization of the [Zn3(H2O)4(μ-gly)2I6] complex have been observed in the Gly - ZnI2 - H2O system at 25°C. Different mixed zinc-glycine-iodide-aqua complexes exist in the studied solutions and those with the highest activity are responsible for the crystallization process. The stable [ZnI2O2(2Gly)]0 complexes are responsible for the large equilibrium crystallization field of the compound [Zn(gly)2I2] (monoclinic system, C2/c space group), in whose crystal structure they are incorporated as discrete distorted electroneutral tetrahedra. In zinc-iodide solutions with a low water activity it is more probable that the glycine zwitterions act as bidentate ligands and form polynuclear complexes. We assume the [ZnI2O2(2/2Gly)]0 infinite chains build the compound [Zn(gly)I2], for which we have found a narrow equilibrium crystallization field. We have failed to describe the crystal structure of this compound because of its limited stability in the air. Non-equilibrium crystallization of [Zn3(H2O)4(μ-gly)2I6] (triclinic system, P-1 space group) was demonstrated, with crystal structure built by trinuclear complexes [ZnI3O(1/2Gly)] [ZnO4(4H2O)O2(2/2Gly)(trans)][ZnI3O(1/2Gly)]. The FTIR and Raman spectra and also the thermal behaviour of the three compounds were discussed.

  11. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures. PMID:26328435

  12. 'Structure, Dynamics and Vibrational Spectrum of Supercritical CO2/H2O Mixtures from Ab Initio Molecular Dynamics as a Function of Water Cluster Formation

    SciTech Connect

    Glezakou, Vassiliki Alexandra; Rousseau, Roger J.; Dang, Liem X.; McGrail, B. Peter

    2010-08-21

    We have studied the effect of water in the supercritical phase of CO2 as a function of water self-association using DFT-based molecular dynamics simulations. The dependence of the intermolecular and intramolecular structure and dynamic properties upon water concentration in the supercritical CO2/H2O phase at a density of 0.81g/cm3 and temperature of 318.15K is investigated in detail and compared to previous studies of the pure sc-CO2 system and Monte-Carlo simulations of water in sc-CO2 phase. Analysis of radial and orientational distribution functions of the intermolecular interactions shows that the presence of water molecules does not disturb the previously established distorted T-shaped orientation of CO2 molecules, though there is strong evidence of perturbation of the second shell structure which enhances the preference for the slipped parallel orientation in this region. There is also evidence of short-lived hydrogen bonds between CO2 and water molecules. For higher water concentrations, water clustering is observed, consistent with the expected phase separation under these conditions of temperature and pressure. Finally, the water-water and water-CO2 interactions are discussed and analyzed in terms of the water self-association and thermodynamic quantities derived from the corresponding radial distribution functions. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  13. Corrosion study on high power feeding of telecomunication copper cable in 5 wt.% CaSO4.2H2O solution

    NASA Astrophysics Data System (ADS)

    Shamsudin, Shaiful Rizam; Hashim, Nabihah; Ibrahim, Mohd Saiful Bahri; Rahman, Muhammad Sayuzi Abdul; Idrus, Muhammad Amin; Hassan, Mohd Rezadzudin; Abdullah, Wan Razli Wan

    2016-07-01

    The studies were carried out to find out the best powering scheme over the copper telephone line. It was expected that the application of the higher power feeding could increase the data transfer and capable of providing the customer's satisfaction. To realize the application of higher remote power feeding, the potential of corrosion problem on Cu cables was studied. The natural corrosion behaviour of copper cable in the 0.5% CaSO4.2H2O solution was studied in term of open circuit potential for 30 days. The corrosion behaviour of higher power feeding was studied by the immersion and the planned interval test to determine the corrosion rate as well as the effect of voltage magnitudes and the current scheme i.e. positive direct (DC+) and alternating current (AC) at about 0.40 ± 0.01 mA/ cm2 current density. In the immersion test, both DC+ and AC scheme showed the increasing of feeding voltage magnitude has increased the corrosion rate of Cu samples starting from 60 to 100 volts. It was then reduced at about 100 - 120 volts which may due to the passive and transpassive mechanism. The corrosion rate was slowly reduced further from 120 to 200 volts. Visually, the positively charged of Cu cable was seems susceptible to severe corrosion, while AC scheme exhibited a slight corrosion reaction on the surface. However, the planned interval test and XRD results showed the corrosion activity of the copper cable in the studied solution was a relatively slow process and considered not to be corroded as a partially protective scale of copper oxide formed on the surface.

  14. Synthesis and crystal structure of Ru III-supported tungstoantimonate [Sb 2W 20Ru III2(H 2O) 2(dmso) 6O 68] 4-

    NASA Astrophysics Data System (ADS)

    Bi, Li-Hua; Li, Bao; Bi, Shuai; Wu, Li-Xin

    2009-06-01

    The first Ru III-supported tungstoantimonate [Ru II(bpy) 3] 2[Sb 2W 20Ru III2(H 2O) 2(dmso) 6O 68]·3dmso (bpy=bi-pyridine) ( 1a) has been successfully isolated as [Ru(bpy) 3] 2+ (Rubpy) salt by routine synthetic reaction in mixed solutions with dmso and water. Single-crystal X-ray analysis was carried out on 1a, which crystallizes in the triclinic system space group P-1 with a=16.804 (6), b=16.988 (6), c=17.666 (6) Å, α=107.397 (13)°, β=106.883 (13)°, γ=103.616 (12)°. V=4309 (3) Å 3, Z=1 with R1=0.0773. The compound 1a reveals the following features: (1) Rubpy is firstly used as an alternative ruthenium-source for the synthesis of Ru-substituted heteropolytungstate; (2) the structure of 1a consists of four Ru III-O-S(CH 3) 2 and two W-O-S(CH 3) 2 bonds resulting in an assembly with C2 symmetry; (3) the Ru III ions are linked to two dmso groups via two Ru III-O-S(CH 3) 2 bonds, which represents the other dmso-coordination mode to Ru III in POM chemistry. The cyclic voltammetry studies of 1a in dmso/H 2SO 4 (3/1 v/v) at pH 2.5 medium using the glassy carbon electrode as a working electrode show the respective electrochemical behaviors of the W-centers and the Ru-centers within 1a, which could be separated clearly. In addition, the compound 1a exhibits photoluminescence arising from π*- t2g ligand-to-metal transition of Rubpy.

  15. Unimolecular Reactions of Dihydrated Alkaline Earth Metal Dications M2+(H2O)2, M = Be, Mg, Ca, Sr, and Ba: Salt-Bridge Mechanism in the Proton-Transfer Reaction M2+(H2O)2 → MOH+ + H3O+

    PubMed Central

    Beyer*, Martin; Williams*, Evan R.; Bondybey*, Vladimir E.

    2005-01-01

    The unimolecular reactivity of M2+(H2O)2, M = Be, Mg, Ca, Sr, and Ba, is investigated by density functional theory. Dissociation of the complex occurs either by proton transfer to form singly charged metal hydroxide, MOH+, and protonated water, H3O+, or by loss of water to form M2+(H2O) and H2O. Charge transfer from water to the metal forming H2O+ and M+(H2O) is not favorable for any of the metal complexes. The relative energetics of these processes are dominated by the metal dication size. Formation of MOH+ proceeds first by one water ligand moving to the second solvation shell followed by proton transfer to this second-shell water molecule and subsequent Coulomb explosion. These hydroxide formation reactions are exothermic with activation energies that are comparable to the water binding energy for the larger metals. This results in a competition between proton transfer and loss of a water molecule. The arrangement with one water ligand in the second solvation shell is a local minimum on the potential energy surface for all metals except Be. The two transition states separating this intermediate from the reactant and the products are identified. The second transition state determines the height of the activation barrier and corresponds to a M2+–OH−–H3O+ “salt-bridge” structure. The computed B3LYP energy of this structure can be quantitatively reproduced by a simple ionic model in which Lewis charges are localized on individual atoms. This salt-bridge arrangement lowers the activation energy of the proton-transfer reaction by providing a loophole on the potential energy surface for the escape of H3O+. Similar salt-bridge mechanisms may be involved in a number of proton-transfer reactions in small solvated metal ion complexes, as well as in other ionic reactions. PMID:16554906

  16. A simple synthesis and characterization of binary Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and its final decomposition product CoFeP 4O 12

    NASA Astrophysics Data System (ADS)

    Boonchom, Banjong; Danvirutai, Chanaiporn; Vittayakorn, Naratip

    2011-01-01

    This paper reports the synthesis of binary Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O by a simple, rapid and cost-effective method using CoCO 3-Fe(c)-H 3PO 4 system in water-acetone media at ambient temperature. Thermal transformation of the synthesized powder was investigated by TG/DTG/DTA and DSC techniques, which indicate that its final decomposed product was a binary cobalt iron cyclotetraphosphate CoFeP 4O 12. The FTIR and XRD results of the synthesized Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and the decomposed CoFeP 4O 12 indicate the pure monoclinic phases with space group P2 1/n and C2/c, respectively. The morphologies of Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and CoFeP 4O 12 powders appear non-uniform particle shapes and high agglomerates, which are different from the cases of the single compounds M(H 2PO 4) 2·2H 2O and M 2P 4O 12 (where M = Co, Fe). The magnetic properties of the studied compounds are superparamagnetic behaviors, which are important for specific applications. The physical properties of the studied powders are comparable with those reported in our previous study, affected by medium and condition of preparation method.

  17. K3B3O4(OH)4·2H2O: A UV Nonlinear Optical Crystal with Isolated [B3O4(OH)4](3-) Anion Groups.

    PubMed

    Liu, Qiong; Zhang, Xiangyu; Yang, Zhihua; Zhang, Fangfang; Liu, Lili; Han, Jian; Li, Zhi; Pan, Shilie

    2016-09-01

    A potential ultraviolet (UV) nonlinear optical (NLO) material, K3B3O4(OH)4·2H2O, was successfully synthesized by hydrothermal methods. The compound crystallizes into the Cmc21 space group and exhibits isolated [B3O4(OH)4](3-) anion groups connected by O-H···O hydrogen bonds. The UV-vis diffuse reflectance spectrum shows that K3B3O4(OH)4·2H2O has a wide transparency range with an absorption edge below 190 nm. Powder second harmonic generation (SHG) measurements using 1064 nm radiation revealed a moderate efficiency, 0.8 × KDP. Additional particle size vs SHG efficiency measurements indicate that K3B3O4(OH)4·2H2O is type I phase-matchable. Our calculated results show that the borate groups as well as the waters of hydration determine the NLO properties of K3B3O4(OH)4·2H2O. PMID:27504674

  18. Toxicity assessment of textile effluents treated by advanced oxidative process (UV/TiO2 and UV/TiO2/H2O2) in the species Artemia salina L.

    PubMed

    Garcia, Juliana Carla; de Souza Freitas, Thábata Karoliny Formicoly; Palácio, Soraya Moreno; Ambrósio, Elizangela; Souza, Maísa Tatiane Ferreira; Santos, Lídia Brizola; de Cinque Almeida, Vitor; de Souza, Nilson Evelázio

    2013-03-01

    Textile industry wastes raise a great concern due to their strong coloration and toxicity. The objective of the present work was to characterize the degradation and mineralization of textile effluents by advanced oxidative processes using either TiO(2) or TiO(2)/H(2)O(2) and to monitor the toxicity of the products formed during 6-h irradiation in relation to that of the in natura effluent. The results demonstrated that the TiO(2)/H(2)O(2) association was more efficient in the mineralization of textile effluents than TiO(2), with high mineralized ion concentrations (NH (4) (+) , NO (3) (-) , and SO (4) (2-) ) and significantly decreased organic matter ratios (represented by the chemical oxygen demand and total organic carbon). The toxicity of the degradation products after 4-h irradiation to Artemia salina L. was not significant (below 10 %). However, the TiO(2)/H(2)O(2) association produced more toxicity under irradiation than the TiO(2) system, which was attributed to the increased presence of oxidants in the first group. Comparatively, the photogenerated products of both TiO(2) and the TiO(2)/H(2)O(2) association were less toxic than the in natura effluent. PMID:22638725

  19. Origin of methane in serpentinite-hosted hydrothermal systems: The CH4-H2-H2O hydrogen isotope systematics of the Hakuba Happo hot spring

    NASA Astrophysics Data System (ADS)

    Suda, Konomi; Ueno, Yuichiro; Yoshizaki, Motoko; Nakamura, Hitomi; Kurokawa, Ken; Nishiyama, Eri; Yoshino, Koji; Hongoh, Yuichi; Kawachi, Kenichi; Omori, Soichi; Yamada, Keita; Yoshida, Naohiro; Maruyama, Shigenori

    2014-01-01

    Serpentinite-hosted hydrothermal systems have attracted considerable attention as sites of abiotic organic synthesis and as habitats for the earliest microbial communities. Here, we report a systematic isotopic study of a new serpentinite-hosted system: the Hakuba Happo hot spring in the Shiroumadake area, Japan (36°42‧N, 137°48‧E). We collected water directly from the hot spring from two drilling wells more than 500 m deep; all water samples were strongly alkaline (pH>10) and rich in H2 (201-664 μmol/L) and CH4 (124-201 μmol/L). Despite the relatively low temperatures (50-60 °C), thermodynamic calculations suggest that the H2 was likely derived from serpentinization reactions. Hydrogen isotope compositions for Happo #1 (Happo #3) were found to be as follows: δD-H2=-700‰ (-710‰), δD-CH4=-210‰ (-300‰), and δD-H2O=-85‰ (-84‰). The carbon isotope compositions of methane from Happo #1 and #3 were found to be δC13=-34.5‰ and -33.9‰, respectively. The CH4-H2-H2O hydrogen isotope systematics indicate that at least two different mechanisms were responsible for methane formation. Happo #1 has a similar hydrogen isotope compositions to other serpentinite-hosted systems reported previously. The elevated δD-CH4 (with respect to the equilibrium relationship) suggests that the hydrogen of the Happo #1 methane was not sourced from molecular hydrogen but was derived directly from water. This implies that the methane may not have been produced via the Fischer-Tropsch-type (FTT) synthesis but possibly by the hydration of olivine. Conversely, the depleted δD-CH4 (with respect to the equilibrium relationship) in Happo #3 suggests the incorporation of biological methane. Based on a comparison of the hydrogen isotope systematics of our results with those of other serpentinite-hosted hydrothermal systems, we suggest that abiotic CH4 production directly from H2O (without mediation by H2) may be more common in serpentinite-hosted systems. Hydration of olivine

  20. Arsenic speciation in synthetic gypsum (CaSO4·2H2O): A synchrotron XAS, single-crystal EPR, and pulsed ENDOR study

    NASA Astrophysics Data System (ADS)

    Lin, Jinru; Chen, Ning; Nilges, Mark J.; Pan, Yuanming

    2013-04-01

    Gypsum (CaSO4·2H2O) is a major by-product of mining and milling processes of borate, phosphate and uranium deposits worldwide and, therefore, potentially plays an important role in the stability and bioavailability of heavy metalloids, including As, in tailings and surrounding areas. Gypsum containing 1900 and 185 ppm As, synthesized with Na2HAsO4·7H2O and NaAsO2 in the starting materials, respectively, have been investigated by synchrotron X-ray absorption spectroscopy (XAS), single-crystal electron paramagnetic resonance spectroscopy (EPR), and pulsed electron nuclear double resonance spectroscopy (ENDOR). Quantitative analyses of As K edge XANES and EXAFS spectra show that arsenic occurs in both +3 and +5 oxidation states and the As3+/As5+ value varies from 0.35 to 0.79. Single-crystal EPR spectra of gamma-ray-irradiated gypsum reveal two types of arsenic-associated oxyradicals: [AsO3]2- and an [AsO2]2-. The [AsO3]2- center is characterized by principal 75As hyperfine coupling constants of A1 = 1952.0(2) MHz, A2 = 1492.6(2) MHz and A3 = 1488.7(2) MHz, with the unique A axis along the S-O1 bond direction, and contains complex 1H superhyperfine structures that have been determined by pulsed ENDOR. These results suggest that the [AsO3]2- center formed from electron trapping on the central As5+ ion of a substitutional (AsO4)3- group after removal of an O1 atom. The [AsO2]2- center is characterized by its unique A(75As) axis approximately perpendicular to the O1-S-O2 plane and the A2 axis along the S-O2 bond direction, consistent with electron trapping on the central As3+ ion of a substitutional (AsO3)3- group after removal of an O2 atom. These results confirm lattice-bound As5+ and As3+ in gypsum and point to potential application of this mineral for immobilization and removal of arsenic pollution.

  1. A calibration of the triple oxygen isotope fractionation in the SiO2-H2O system and applications to natural samples

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Gibbons, J. A.; Maltsev, O.; Atudorei, V.; Pack, A.; Sengupta, S.; Shock, E. L.; Knauth, L. P.

    2016-08-01

    It is now recognized that variations in the Δ17O of terrestrial materials resulting from purely mass dependent fractionations, though small, have geological significance. In this study, the δ18O and δ17O values of selected low temperature quartz and silica samples were measured in order to derive the quartz-water fractionation-temperature relationship for the three oxygen isotope system. A 18O/16O quartz-water fractionation equation valid for all temperatures was generated from published high temperature exchange experiments and low temperature empirical estimates and is given by 1000ln αqz-H2O 18O /16O =4.20 (0.11) ×106/T2 - 3.3 (0.2) × 1000/T (T in Kelvins). The equilibrium δ17O-δ18O relationship is given by the equation lnα17O/16O = θlnα18O/16O . The variation of θ with temperature for the quartz-water system was determined empirically using low temperature marine diatoms, microcrystalline quartz and a modern sinter sample. A best fit to the data give the equation θSiO2-H2O = -(1.85 ± 0.04)/T + 0.5305 , indistinguishable from an earlier theoretical estimate. Application of the quartz-water triple isotope system to low temperature samples provides constraints on both temperature and composition of the water with which the silica last equilibrated. Authigenic quartz crystallization temperatures cluster around 50 °C, which are lower than many previous estimates. The combined δ18O and δ17O values of samples considered to be in equilibrium with ocean or meteoric waters can be used to estimate both formation temperatures and the δ18O value of the meteoric water. Unlike other multiple isotopes systems, such as combined H and O isotopes in cherts, the oxygen source and diagenetic potential for both 17O/16O and 18O/16O ratios are identical, simplifying interpretations from ancient samples.

  2. A calibration of the triple oxygen isotope fractionation in the SiO2-H2O system and applications to natural samples

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Gibbons, J. A.; Maltsev, O.; Atudorei, V.; Pack, A.; Sengupta, S.; Shock, E. L.; Knauth, L. P.

    2016-08-01

    It is now recognized that variations in the Δ17O of terrestrial materials resulting from purely mass dependent fractionations, though small, have geological significance. In this study, the δ18O and δ17O values of selected low temperature quartz and silica samples were measured in order to derive the quartz-water fractionation-temperature relationship for the three oxygen isotope system. A 18O/16O quartz-water fractionation equation valid for all temperatures was generated from published high temperature exchange experiments and low temperature empirical estimates and is given by 1000ln αqz-H2O18O /16O = 4.20 (0.11) ×106/T2 - 3.3 (0.2) × 1000/T (T in Kelvins). The equilibrium δ17O-δ18O relationship is given by the equation lnα17O/16O = θlnα18O/16O . The variation of θ with temperature for the quartz-water system was determined empirically using low temperature marine diatoms, microcrystalline quartz and a modern sinter sample. A best fit to the data give the equation θSiO2 - H2O = -(1.85 ± 0.04)/T + 0.5305 , indistinguishable from an earlier theoretical estimate. Application of the quartz-water triple isotope system to low temperature samples provides constraints on both temperature and composition of the water with which the silica last equilibrated. Authigenic quartz crystallization temperatures cluster around 50 °C, which are lower than many previous estimates. The combined δ18O and δ17O values of samples considered to be in equilibrium with ocean or meteoric waters can be used to estimate both formation temperatures and the δ18O value of the meteoric water. Unlike other multiple isotopes systems, such as combined H and O isotopes in cherts, the oxygen source and diagenetic potential for both 17O/16O and 18O/16O ratios are identical, simplifying interpretations from ancient samples.

  3. Attikaite, Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O, a new mineral species

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Pekov, I. V.; Zadov, A. E.

    2007-12-01

    Attikaite, a new mineral species, has been found together with arsenocrandalite, arsenogoyazite, conichalcite, olivenite, philipsbornite, azurite, malachite, carminite, beudantite, goethite, quartz, and allophane at the Christina Mine No. 132, Kamareza, Lavrion District, Attiki Prefecture (Attika), Greece. The mineral is named after the type locality. It forms spheroidal segregations (up to 0.3 mm in diameter) consisting of thin flexible crystals up to 3 × 20 × 80 μm in size. Its color is light blue to greenish blue, with a pale blue streak. The Mohs’ hardness is 2 to 2.5. The cleavage is eminent mica-like parallel to {001}. The density is 3.2(2) g/cm3 (measured in heavy liquids) and 3.356 g/cm3 (calculated). The wave numbers of the absorption bands in the infrared spectrum of attikaite are (cm-1; sh is shoulder; w is a weak band): 3525 sh, 3425, 3180, 1642, 1120 w, 1070 w, 1035 w, 900 sh, 874, 833, 820, 690 w, 645 w, 600 sh, 555, 486, 458, and 397. Attikaite is optically biaxial, negative, α = 1.642(2), β = γ = 1.644(2) ( X = c) 2 V means = 10(8)°, and 2 V calc = 0°. The new mineral is microscopically colorless and nonpleochroic. The chemical composition (electron microprobe, average over 4 point analyses, wt %) is: 0.17 MgO, 17.48 CaO, 0.12 FeO, 16.28 CuO, 10.61 Al2O3, 0.89 P2O5, 45.45 As2O5, 1.39 SO3, and H2O (by difference) 7.61, where the total is 100.00. The empirical formula calculated on the basis of (O,OH,H2O)22 is: Ca2.94Cu{1.93/2+} Al1.97Mg0.04Fe{0.02/2+} [(As3.74S0.16P0.12)Σ4.02O16.08](OH)3.87 · 2.05H2 O. The simplified formula is Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O. Attikaite is orthorhombic, space group Pban, Pbam or Pba2; the unit-cell dimensions are a = 10.01(1), b = 8.199(5), c = 22.78(1) Å, V = 1870(3) Å3, and Z = 4. In the result of the ignition of attikaite for 30 to 35 min at 128 140°, the H2O bands in the IR spectrum disappear, while the OH-group band is not modified; the weight loss is 4.3%, which approximately corresponds to two H2O

  4. Nickeltalmessite, Ca2Ni(AsO4)2 · 2H2O, a new mineral species of the fairfieldite group, Bou Azzer, Morocco

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Mukhanova, A. A.; Möckel, S.; Belakovsky, D. I.; Levitskaya, L. A.

    2010-12-01

    Nickeltalmessite, Ca2Ni(AsO4)2 · 2H2O, a new mineral species of the fairfieldite group, has been found in association with annabergite, nickelaustinite, pecoraite, calcite, and a mineral of the chromite-manganochromite series from the dump of the Aït Ahmane Mine, Bou Azzer ore district, Morocco. The new mineral occurs as spheroidal aggregates consisting of split crystals up to 10 × 10 × 20 μm in size. Nickeltalmessite is apple green, with white streak and vitreous luster. The density measured by the volumetric method is 3.72(3) g/cm3; calculated density is 3.74 g/cm3. The new mineral is colorless under a microscope, biaxial, positive: α = 1.715(3), β = 1.720(5), γ = 1.753(3), 2 V meas = 80(10)°, 2 V calc = 60.4. Dispersion is not observed. The infrared spectrum is given. As a result of heating of the mineral in vacuum from 24° up to 500°C, weight loss was 8.03 wt %. The chemical composition (electron microprobe, wt %) is as follows: 25.92 CaO, 1.23 MgO, 1.08 CoO, 13.01 NiO, 52.09 As2O5; 7.8 H2O (determined by the Penfield method); the total is 101.13. The empirical formula calculated on the basis of two AsO4 groups is Ca2.04(Ni0.77Mg0.13Co0.06)Σ0.96 (AsO4)2.00 · 1.91H2O. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are: 5.05 (27) (001) (100), 3.57 (43) (011), 3.358 (58) (110), 3.202 (100) (020), 3.099 (64) (0 bar 2 1), 2.813 (60), ( bar 1 21), 2.772 (68) (2 bar 1 0), 1.714 (39) ( bar 3 31). The unit-cell dimensions of the triclinic lattice (space group P1 or P) determined from the X-ray powder data are: a = 5.858(7), b = 7.082(12), c = 5.567(6) Å, α = 97.20(4), β = 109.11(5), γ = 109.78(5)°, V = 198.04 Å3, Z = 1. The mineral name emphasizes its chemical composition as a Ni-dominant analogue of talmessite. The type material of nickeltalmessite is deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, registration number 3750/1.

  5. Middendorfite, K3Na2Mn5Si12(O,OH)36 · 2H2O, a new mineral species from the Khibiny pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Chukanov, N. V.; Dubinchuk, V. T.; Zadov, A. E.

    2007-12-01

    Middendorfite, a new mineral species, has been found in a hydrothermal assemblage in Hilairite hyperperalkaline pegmatite at the Kirovsky Mine, Mount Kukisvumchorr apatite deposit, Khibiny alkaline pluton, Kola Peninsula, Russia. Microcline, sodalite, cancrisilite, aegirine, calcite, natrolite, fluorite, narsarsukite, labuntsovite-Mn, mangan-neptunite, and donnayite are associated minerals. Middendorfite occurs as rhombshaped lamellar and tabular crystals up to 0.1 × 0.2 × 0.4 mm in size, which are combined in worm-and fanlike segregations up to 1 mm in size. The color is dark to bright orange, with a yellowish streak and vitreous luster. The mineral is transparent. The cleavage (001) is perfect, micalike; the fracture is scaly; flakes are flexible but not elastic. The Mohs hardness is 3 to 3.5. Density is 2.60 g/cm3 (meas.) and 2.65 g/cm3 (calc.). Middendorfite is biaxial (-), α = 1.534, β = 1.562, and γ = 1.563; 2 V (meas.) = 10°. The mineral is pleochroic strongly from yellowish to colorless on X through brown on Y and to deep brown on Z. Optical orientation: X = c. The chemical composition (electron microprobe, H2O determined with Penfield method) is as follows (wt %): 4.55 Na2O, 10.16 K2O, 0.11 CaO, 0.18 MgO, 24.88 MnO, 0.68 FeO, 0.15 ZnO, 0.20 Al2O3, 50.87 SiO2, 0.17 TiO2, 0.23 F, 7.73 H2O; -O=F2-0.10, total is 99.81. The empirical formula calculated on the basis of (Si,Al)12(O,OH,F)36 is K3.04(Na2.07Ca0.03)Σ2.10(Mn4.95Fe0.13Mg0.06Ti0.03Zn0.03)Σ5.20(Si11.94Al0.06)Σ12O27.57(OH)8.26F0.17 · 1.92H2O. The simplified formula is K3Na2Mn5Si12(O,OH)36 · 2H2O. Middenforite is monoclinic, space group: P21/ m or P21. The unit cell dimensions are a = 12.55, b = 5.721, c = 26.86 Å; β = 114.04°, V = 1761 Å3, Z = 2. The strongest lines in the X-ray powder pattern [ d, Å, ( I)( hkl)] are: 12.28(100)(002), 4.31(81)(11overline 4 ), 3.555(62)(301, 212), 3.063(52)(008, 31overline 6 ), 2.840(90)(312, 021, 30overline 9 ), 2.634(88)(21overline 9 , 1.0.overline 1 0

  6. Zn3(OH)2V2O7·2H2O/g-C3N4: A novel composite for efficient photodegradation of methylene blue under visible-light irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Qizhao; Zheng, Longhui; Bai, Yan; Zhao, Jianjun; Wang, Fangping; Zhang, Rong; Huang, Haohao; Su, Bitao

    2015-08-01

    In this work, we used a facile method to prepare a series of Zn3(OH)2V2O7·2H2O/g-C3N4 composites in a 70 °C water bath for 10 h and characterized them by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET), and photoluminescence (PL). Degradation of methylene blue (MB) and phenol were carried out to evaluate the photocatalytic activities of samples under visible light irradiation. Presence of Zn3(OH)2V2O7·2H2O increased surface areas and promoted the charge separation, exerted great influence on the photocatalytic activity and absorption capacity of g-C3N4. In addition, the synergic effect was explained and a possible photocatalytic mechanism was proposed.

  7. Solid-liquid phase equilibria at 50 and 75°C in the NaCl + MgCl2 + H2O system and the pitzer model representations

    NASA Astrophysics Data System (ADS)

    Yang, Ji-min; Zhang, Rui-zhi; Liu, Hong; Ma, Si-hong

    2013-12-01

    The solubilities in the NaCl-MgCl2-H2O system were determined at 50 and 75°C and the phase diagrams were constructed on the base of experimental data. One invariant point, two univariant curves, and two crystallization zones, corresponding to sodium chloride and dihydrate (MgCl2 · 6H2O) showed up in the phase diagrams of the ternary system, The mixing parameters θNa,Mg and ΨNa,Mg, Cl and equilibrium constant K sp were evaluated in NaCl-MgCl2-H2O system by least-squares optimization procedure, in which the single-salt Pitzer parameters of NaCl and MgCl2β(0), β(1), and C φ were directly calculated from the literature. The results obtained were in good agreement with the experimental data.

  8. Be(3)(AsO4)2. 2H2O, a new berylloarsenate phase containing bridged tetrahedral 3-rings. Technical report, 1 June 1992-31 May 1993

    SciTech Connect

    Harrison, W.T.; Nenoff, T.M.; Gier, T.E.; Stucky, G.D.

    1993-02-15

    The high-temperature/high-pressure hydrothermal synthesis and X-ray single crystal structure of Be3(AsO4)2(dot)2H2O is described: the title compound contains a three-dimensional network of BeO4 and AsO4 tetrahedra. The structural motif includes infinite layers of bridged tetrahedral 3- and 4-rings. 9Be MAS NMR data are consistent with the Be-atom environments in the crystal structure.

  9. Room temperature synthesis of rod-like FeC2O4·2H2O and its transition to maghemite, magnetite and hematite nanorods through controlled thermal decomposition

    NASA Astrophysics Data System (ADS)

    Zhou, Weiwei; Tang, Kaibin; Zeng, Suyuan; Qi, Yunxia

    2008-02-01

    FeC2O4·2H2O nanorods with diameter of about 50 nm and length of up to several micrometers were synthesized at room temperature in a surfactant-assisted system, which was obtained by dissolving bis(2-ethylhexyl)sodium sulfosuccinate (AOT) in a mixed solution composed of water and ethylene glycol (EG). The influence of reaction conditions on the morphology of FeC2O4·2H2O is discussed in detail. Through direct thermal decomposition of FeC2O4·2H2O under different calcination conditions, maghemite (γ-Fe2O3), magnetite (Fe3O4) and hematite (α-Fe2O3) can be selectively obtained, preserving the rod-like morphology. Transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) characterizations showed that the as-obtained iron oxide nanorods were composed of fine particles with different crystal orientations. The magnetic properties of the as-obtained iron oxide nanorods were systematically investigated.

  10. Synthesis, structure, properties and biological behaviour of the complex [RuIV (H2L) Cl2].2H2O (H4L= 1,2-cyclohexanediamminetetraacetic acid).

    PubMed

    Vilaplana, Rosario A; Castiñeiras, A; González-Vílchez, Francisco

    2004-01-01

    The highly water-soluble ruthenium complex [Ru(H(2)L)Cl(2)](2)H(2)o, in which H(4)L is the sequestering ligand trans-l, 2-cyclohexanediamminetetraacetic acid (cdta) has been synthesized, structurally characterized and its properties studied. The X-ray crystallographic study shows that the chelating coordinated ligand is tetradentate while the ruthenium environment is octahedral and slightly distorted, with two chloride anions coordinated in cis positions. Potentiometric, conductimetric and infrared studies confirm the presence of two free carboxylic groups, while electronic and voltammetric studies show that the central ion is Ru(IV). The testing of the cytotoxic activity of this complex against three different human cancer cell lines indicates that [Ru(H(2)L)Cl(2)].2H(2)O shows a remarkable and selective antiproliferative effect against the human uterine neck carcinoma HeLa and the malign adenocarcinoma ADLD, showing only a discrete turnout cell inhibition activity against colon adenocarcinoma HT-29. The important antiprotiferative behaviour of complex 1 against the human adenocarcinoma ADLD, indicates that [Ru(H(2)L)Cl(2)].2H(2)O might be considered as potential antineoplastic compound. PMID:18365080

  11. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)(2)(H(2)O)]. 4H(2)O, [Mn(Phen)(2)(H(2)O)(2)](2)(Isoph)(2)(Phen). 12H(2)O and {[Mn(Isoph)(bipy)](4). 2.75biby}(n)(phH(2) = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine).

    PubMed

    Devereux, M; McCann, M; Leon, V; Geraghty, M; McKee, V; Wikaira, J

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH(2)) to give [Mn(ph)].0.5H(2)O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)].2H(2)O (2) and [Mn(ph)(phen)(2)(H(2)O)].4H(2)O (3). Reaction of isophthalic acid (isophH(2)) with manganese(II) acetate results in the formation of [Mn(isoph)].2H(2)O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn(2) (isoph)(2)(phen)(3))].4H(2)O (5), [(Mn(phen)(2)(H(2)O)(2)](2)(isoph)(2)(phen).12H(2)O (6) and {[Mn(isoph)(bipy)](4).2.75 biby}(n) (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the "metal free" 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  12. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)2(H2O)]· 4H2O, [Mn(Phen)2(H2O)2]2(Isoph)2(Phen)· 12H2O and {[Mn(Isoph)(bipy)]4· 2.75biby}n(phH2 = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine)

    PubMed Central

    McCann, Malachy; Leon, Vanessa; Geraghty, Majella; McKee, Vickie; Wikaira, Jan

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH2) to give [Mn(ph)]·0.5H2O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)]·2H2O (2) and [Mn(ph)(phen)2(H2O)]·4H2O (3). Reaction of isophthalic acid (isophH2) with manganese(II) acetate results in the formation of [Mn(isoph)]·2H2O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn2 (isoph)2(phen)3)]·4H2O (5), [(Mn(phen)2(H2O)2]2(isoph)2(phen)·12H2O (6) and {[Mn(isoph)(bipy)]4·2.75 biby}n (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the “metal free” 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  13. Synthesis, structure, and characterization of two new polar sodium tungsten selenites: Na2(WO3)3(SeO3)·2H2O and Na6(W6O19)(SeO3)2.

    PubMed

    Nguyen, Sau Doan; Halasyamani, P Shiv

    2013-03-01

    Two new quaternary sodium tungsten selenites, Na2(WO3)3(SeO3)·2H2O (P31c) and Na6(W6O19)(SeO3)2 (C2), have been synthesized and characterized. The former exhibits a hexagonal tungsten oxide layered structure, whereas the latter has a one-dimensional "ribbon" structure. The layers and "ribbons" consist of distorted WO6 and asymmetric SeO3 polyhedra. The layers in Na2(WO3)3(SeO3)·2H2O and the "ribbons" in Na6(W6O19)(SeO3)2 are separated by Na(+) cations. Powder second-harmonic-generation (SHG) measurements on Na2(WO3)3(SeO3)·2H2O and Na6(W6O19)(SeO3)2 using 1064 nm radiation reveal SHG efficiencies of approximately 450× and 20× α-SiO2, respectively. Particle size versus SHG efficiency measurements indicate that the materials are type 1 non-phase-matchable. Converse piezoelectric measurements result in d33 values of approximately 23 and 12 pm/V, whereas pyroelectric measurements reveal coefficients of -0.41 and -1.10 μC/m(2)·K at 60 °C for Na2(WO3)3(SeO3)·2H2O and Na6(W6O19)(SeO3)2, respectively. Frequency-dependent polarization measurements confirm that the materials are nonferroelectric; i.e., the macroscopic polarization is not reversible, or "switchable". IR and UV-vis spectroscopy, thermogravimetric and differential thermal analysis measurements, and electron localization function calculations were also done for the materials. Crystal data: Na2(WO3)3(SeO3)·2H2O, trigonal, space group P31c (No. 159), a = 7.2595(6) Å, b = 7.2595(6) Å, c = 12.4867(13) Å, V = 569.89(9) Å(3), Z = 2; Na6(W6O19)(SeO3)2, monoclinic, space group C2 (No. 5), a = 42.169(8) Å, b = 7.2690(15) Å, c = 6.7494(13) Å, β = 98.48(3)°, V = 2046.2(7) Å(3), Z = 4. PMID:23425251

  14. A thermodynamic model for the system SiO2-H2O near the upper critical end point based on quartz solubility experiments at 500-1100 °C and 5-20 kbar

    NASA Astrophysics Data System (ADS)

    Hunt, Jonathan D.; Manning, Craig E.

    2012-06-01

    A thermodynamic model of SiO2-H2O mixing in sub- and supercritical fluids has been developed based on new and existing experimental data on the solubility of quartz in H2O. To supplement previously published data, we conducted new solubility experiments at 15 and 20 kbar and 900-1100 °C using hydrothermal piston-cylinder methods. At concentrations below ∼10 mol% SiO2, solubility was measured by single-crystal weight loss. At higher concentrations, solubility was determined by bracketing the presence and absence of quartz in quenched charges using multiple isothermal and isobaric runs with varying SiO2-H2O ratios. These data were combined with previously published results to construct a thermodynamic model of SiO2-H2O mixing. Following studies of silicate melts, the model takes oxygen in the fluid to be in three forms: free, molecular H2O, Si-bridging oxygens (Obr2-), and the terminal hydroxyls (OHtm-) of silanol groups. The equilibrium exchange of oxygen between these forms can be written 1/2 >H2O+1/2 >Obr2-=OHtm-. The standard Gibbs free energy change of this reaction (ΔG∘) was incorporated into a subregular solution model for mixing of SiO2 liquid and H2O fluid. The P-T dependences of ΔG∘ and interchange energies were derived by an error minimization algorithm, producing thirteen independent fit parameters. The model is applicable from 5 to 20 kbar and 500 °C to the dry melting curve of quartz. It reproduces experimentally derived quartz solubility data to 3.8% on average (1σ = 5.3%). The model also predicts hydrous melting of quartz, critical melt-vapor mixing, activity-concentration relations, partial molar volume and entropy of aqueous silica, water speciation, and the thermal expansivity, isothermal compressibility, and isobaric heat capacity of a fluid in equilibrium with quartz. The model predicts a critical end point in the SiO2-H2O system at 1067 °C and 9.33 kbar, in very good agreement with the accepted location at ∼1080 °C and 9.5-10 kbar

  15. Degradation of 5-FU by means of advanced (photo)oxidation processes: UV/H2O2, UV/Fe2+/H2O2 and UV/TiO2--Comparison of transformation products, ready biodegradability and toxicity.

    PubMed

    Lutterbeck, Carlos Alexandre; Wilde, Marcelo Luís; Baginska, Ewelina; Leder, Christoph; Machado, Ênio Leandro; Kümmerer, Klaus

    2015-09-15

    The present study investigates the degradation of the antimetabolite 5-fluorouracil (5-FU) by three different advanced photo oxidation processes: UV/H2O2, UV/Fe(2+)/H2O2 and UV/TiO2. Prescreening experiments varying the H2O2 and TiO2 concentrations were performed in order to set the best catalyst concentrations in the UV/H2O2 and UV/TiO2 experiments, whereas the UV/Fe(2+)/H2O2 process was optimized varying the pH, Fe(2+) and H2O2 concentrations by means of the Box-Behnken design (BBD). 5-FU was quickly removed in all the irradiation experiments. The UV/Fe(2+)/H2O2 and UV/TiO2 processes achieved the highest degree of mineralization, whereas the lowest one resulted from the UV/H2O2 treatment. Six transformation products were formed during the advanced (photo)oxidation processes and identified using low and high resolution mass spectrometry. Most of them were formed and further eliminated during the reactions. The parent compound of 5-FU was not biodegraded, whereas the photolytic mixture formed in the UV/H2O2 treatment after 256 min showed a noticeable improvement of the biodegradability in the closed bottle test (CBT) and was nontoxic towards Vibrio fischeri. In silico predictions showed positive alerts for mutagenic and genotoxic effects of 5-FU. In contrast, several of the transformation products (TPs) generated along the processes did not provide indications for mutagenic or genotoxic activity. One exception was TP with m/z 146 with positive alerts in several models of bacterial mutagenicity which could demand further experimental testing. Results demonstrate that advanced treatment can eliminate parent compounds and its toxicity. However, transformation products formed can still be toxic. Therefore toxicity screening after advanced treatment is recommendable. PMID:25965036

  16. Photodegradation of the antineoplastic cyclophosphamide: a comparative study of the efficiencies of UV/H2O2, UV/Fe2+/H2O2 and UV/TiO2 processes.

    PubMed

    Lutterbeck, Carlos Alexandre; Machado, Ênio Leandro; Kümmerer, Klaus

    2015-02-01

    Anticancer drugs are harmful substances that can have carcinogenic, mutagenic, teratogenic, genotoxic, and cytotoxic effects even at low concentrations. More than 50 years after its introduction, the alkylating agent cyclophosphamide (CP) is still one of the most consumed anticancer drug worldwide. CP has been detected in water bodies in several studies and is known as being persistent in the aquatic environment. As the traditional water and wastewater treatment technologies are not able to remove CP from the water, different treatment options such as advanced oxidation processes (AOPs) are under discussion to eliminate these compounds. The present study investigated the degradation of CP by three different AOPs: UV/H2O2, UV/Fe(2+)/H2O2 and UV/TiO2. The light source was a Hg medium-pressure lamp. Prescreening tests were carried out and afterwards experiments based on the optimized conditions were performed. The primary elimination of the parent compounds and the detection of transformation products (TPs) were monitored with LC-UV-MS/MS analysis, whereas the degree of mineralization was monitored by measuring the dissolved organic carbon (DOC). Ecotoxicological assays were carried out with the luminescent bacteria Vibrio fischeri. CP was completely degraded in all treatments and UV/Fe(2+)/H2O2 was the fastest process, followed by UV/H2O2 and UV/TiO2. All the reactions obeyed pseudo-first order kinetics. Considering the mineralization UV/Fe(2+)/H2O2 and UV/TiO2 were the most efficient process with mineralization degrees higher than 85%, whereas UV/H2O2 achieved 72.5% of DOC removal. Five transformation products were formed during the reactions and identified. None of them showed significant toxicity against V. fischeri. PMID:25303738

  17. Nqrs Data for C8H5Li2O4.5 [C8H4Li2O4·1/2(H2O)] (Subst. No. 1059)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H5Li2O4.5 [C8H4Li2O4·1/2(H2O)] (Subst. No. 1059)

  18. Energy transport in photoexcited crystals of K3[Tb(C2O4)3(H2O)].2H2O: Transfer from Tb3+ to Nd3+ and Eu3+

    NASA Astrophysics Data System (ADS)

    Kahwa, Ishenkumba A.; Parkes, Charmaine C.; McPherson, Gary L.

    1995-10-01

    The luminescence decay dynamics of Tb3+(5D4) and Eu(5D0) in triclinic (P1¯) crystalline K3[Ln(C2O4)3(H2O)].2H2O solids was studied between 10 and 298 K in order to establish the energy-transport characteristics. The luminescence decay rate of Tb3+ (740 s-1 for Ln=Tb3+) is temperature independent for the pure terbium complex; with introduction of Ln3+ dopants (e.g., Ln=Nd, Eu) faster decay rates which are temperature dependent are obtained. For the Eu3+ dopant, excitation buildup on the Eu3+(5D0) decay curve upon Tb3+(5D4) excitation confirms that energy transfer from Tb3+(5D4) to Ln3+ is active. The temperature dependence of the energy-transfer process in the K3[Eu0.83Tb0.17(C2O4)3(H2O)].2H2O mixed complex is well described by a relatively simple empirical expression based on Boltzmann's statistical dynamics of Eu3+ electronic energy among the 7FJ (J=0,1,2) terms. The limiting Eu3+-Tb3+ transfer rates are ~5.4×103 and 5.3×104 s-1 at 77 and 298 K, respectively. Energy migration on the terbium sublattice was confirmed by comparing Huber's [Phys. Rev. B 20, 2707 (1979)] trapping functions for K3[Eu0.4Tb0.6(C2O4)3(H2O)].2H2O and K3[Eu0.4Tb0.1Gd0.5(C2O4)3(H2O)].2H2O (Gd3+ serving as a scatterer for Tb3+ excitation). Although the structure of the complexes features a one-dimensional zigzag array of Ln3+ ions, energy transport is diffusive and not one dimensional.

  19. Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2]2+ (dmp = 2,9-dimethylphenanthroline).

    PubMed

    Kogan, Vladimir; Quintal, Miriam M; Neumann, Ronny

    2005-10-27

    [reaction: see text] [cis-Ru(II)(dmp)2(H2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral. PMID:16235952

  20. Metal-containing ligands for mixed-metal polymers: novel Cu(II)-Ag(I) mixed-metal coordination polymers generated from [Cu(2-methylpyrazine-5-carboxylate)2(H2O)].3H2O and silver(I) salts.

    PubMed

    Dong, Y B; Smith, M D; zur Loye, H C

    2000-05-01

    One Cu(II)-containing ligand and two Cu(II)-Ag(I) mixed-metal coordination polymers have been synthesized. [Cu(2-methylpyrazine-5-carboxylate)2(H2O)].3H2O (1) was obtained as a molecular complex with two uncoordinated nitrogen donors by the reaction of 2-methylpyrazine-5-carboxylate sodium with CuCl(2).2H2O in water. Compound 1 crystallized in the triclinic space group P1, with a = 10.498(2) A, b = 11.000(2) A, c = 8.1424(16) A, alpha = 98.33(3) degrees, beta = 101.83(3) degrees, gamma = 66.68(3) degrees, and Z = 2. Reactions of 1 with silver(I) salts have been studied. Two Cu(II)-Ag(I) mixed-metal coordination polymers, namely, Ag[Cu(2-methylpyrazine-5-carboxylate)2.(H2O)2](BF4) (2) and Ag[Cu(2-methylpyrazine-5-carboxylate)2.(H2O)2](NO3) (3), have been generated by treating 1 with AgBF4 and AgNO3, respectively. Compound 2 crystallized in the monoclinic space group C2/c, with a = 25.827(5) A, b = 9.6430(19) A, c = 7.4525(15) A, beta = 94.74(3) degrees, and Z = 4. Compound 3 also crystallized in the monoclinic space group C2/c, with a = 25.855(5) A, b = 9.782(2) A, c = 7.1201(14) A, beta = 96.90(3) degrees, and Z = 4. The main structural feature in both 2 and 3 is a zigzag Cu(II)-Ag(I) mixed-metal chain, in which the alternating Cu(II) and Ag(I) centers are linked by 2-methylpyrazine-5-carboxylate spacers. The effect of the nitrate counterion was illustrated by compound 3, in which a novel [Ag+...NO3-] coordination chain has been found which acts as the connector to cross-link the one-dimensional zigzag chains into a three-dimensional network. In addition, an identical interchain O-H...O hydrogen bonding system has been found in both 2 and 3 and has been shown to play a significant role in directing the alignment of the one-dimensional mixed-metal polymer chains in the crystalline state. The magnetic susceptibilities of 2 and 3 were measured and found to follow the Curie law (mu eff = 1.85 for 2 and 1.83 for 3). PMID:11428114

  1. Monitoring dehydration of the organic-inorganic [(C3H7)4N][SnCl5(H2O)]·2H2O compound using simultaneous thermal and Raman studies.

    PubMed

    Hajlaoui, S; Chaabane, I; Guidara, K; Bulou, A

    2016-07-01

    In this work we report the experimental studies of the structural phase transition in the [(C3H7)4N]SnCl5(H2O)]·2H2O compound by differential scanning calorimetric (DSC) and Raman spectroscopic. The X-ray powder diffraction study of the [(C3H7)4N][SnCl5(H2O)]·2H2O sample at room temperature showed that this compound is monoclinic and has P121/c1 space group. Differential scanning calorimetric disclosed two types of phase transitions in the temperature range 356-376 (T1) K and at 393K (T2) characterized, by a loss of water molecules and probably a reconstruction of new anionic parts after T2 transition. The Raman scattering spectra recorded at various temperatures in the wavenumber range from 100 to 3800cm(-1) covering the domains of existence of changes in the vicinity of the two phase transitions detected by DSC measurement. A detailed study of the spectral parameters (wave number, reduced intensity and the full width at half maximum) as a function of temperature of a chosen band, associated with (νs(SnO)+νs(SnCl)), based on an order-disorder model allowed us to obtain information relative to the activation energy and correlation length. PMID:27070530

  2. A novel blue luminescent material Na2[Co(C2O4)2(H2O)2]·6H2O: synthesis, structure, luminescence and magnetic properties.

    PubMed

    Saritha, A; Raju, B; Narsimhulu, M; Rao, D Narayana; Raghavaiah, P; Hussain, K A

    2016-05-17

    The synthesis, crystal structure and physical properties of new disodium trans-diaquabis(oxalato)cobaltate(ii)hexahydrate {Na2[Co(C2O4)2(H2O)2]·6H2O} crystals have been investigated. Single crystal X-ray analysis reveals that this compound crystallizes in the triclinic system with the space group P1[combining macron]. The structure of this complex consists of [Co(C2O4)2(H2O)2](2-) anionic units with a slightly distorted octahedral geometry of cobalt surrounded by four oxygen atoms of two oxalate groups. The anionic units are interlinked by two Na(+) ions with different octahedral and distorted octahedral environments. The electronic absorption spectra of the compound exhibit bands at 208, 246 and 526 nm in the UV and visible regions. A strong blue luminescence was observed at room temperature when excited at 355 nm. The M(H) curve at 2 K shows a significant nonlinear behaviour with almost zero coercivity which clearly indicates an extremely weak antiferromagnetic/ferromagnetic state of the complex. PMID:27116226

  3. Probing the microsolvation of a quaternary ion complex: gas phase vibrational spectroscopy of (NaSO4(-))2(H2O)(n=0-6, 8).

    PubMed

    Wende, Torsten; Heine, Nadja; Yacovitch, Tara I; Asmis, Knut R; Neumark, Daniel M; Jiang, Ling

    2016-01-01

    We report infrared multiple photon dissociation spectra of cryogenically-cooled (NaSO4(-))2(H2O)n dianions (n = 0-6, 8) in the spectral range of the sulfate stretching and bending modes (580-1750 cm(-1)). Characteristic absorption bands and structural trends are identified based on a comparison to harmonic spectra of minimum-energy structures. The bare quarternary complex (NaSO4(-))2 exhibits a C2h structure containing two fourfold-coordinated sodium cations in-between the two chelating sulfate dianions. Its stepwise solvation is driven by an interplay of SO4(2-)-H2O and Na(+)-H2O interactions. The first water binds in a tridentate intersulfate-bridging fashion. The second and third water molecules bind to the sulfate groups at either end of the complex, which is followed by the onset of water hydrogen-bond network formation. In contrast to the binary ion pair, NaSO4(-), no clear evidence for the disruption of the quaternary ion complex upon microhydration is found up to n = 8, underlining its remarkable stability and suggesting that the formation of quaternary ion complexes plays a central role in the initial stages of prenucleation in aqueous Na2SO4 solutions. PMID:26608709

  4. Theoretical characterization of the reaction CH3 +OH yields CH3OH yeilds products: The (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO channels

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1993-01-01

    The potential energy surface (PES) for the CH3OH system has been characterized for the (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO product channels using complete-active-space self-consistent-field (CASSCF) gradient calculations to determine the stationary point geometries and frequencies followed by CASSCF/internally contracted configuration-interaction (CCI) calculations to refine the energetics. The (1)CH2 + H2O channel is found to have no barrier. The long range interaction is dominated by the dipole-dipole term, which orients the respective dipole moments parallel to each other but pointing in opposite directions. At shorter separations there is a dative bond structure in which a water lone pair donates into the empty a" orbital of CH2. Subsequent insertion of CH2 into an OH bond of water have barriers located at -5.2 kcal/mol and 1.7 kcal/mol, respectively, with respect to CH3 + OH. From comparison of the computed energetics of the reactants and products to known thermochemical data it is estimated that the computed PES is accurate to plus or minus 2 kcal/mol.

  5. Monitoring dehydration of the organic-inorganic [(C3H7)4N][SnCl5(H2O)]·2H2O compound using simultaneous thermal and Raman studies

    NASA Astrophysics Data System (ADS)

    Hajlaoui, S.; Chaabane, I.; Guidara, K.; Bulou, A.

    2016-07-01

    In this work we report the experimental studies of the structural phase transition in the [(C3H7)4N]SnCl5(H2O)]·2H2O compound by differential scanning calorimetric (DSC) and Raman spectroscopic. The X-ray powder diffraction study of the [(C3H7)4N][SnCl5(H2O)]·2H2O sample at room temperature showed that this compound is monoclinic and has P121/c1 space group. Differential scanning calorimetric disclosed two types of phase transitions in the temperature range 356-376 (T1) K and at 393 K (T2) characterized, by a loss of water molecules and probably a reconstruction of new anionic parts after T2 transition. The Raman scattering spectra recorded at various temperatures in the wavenumber range from 100 to 3800 cm- 1 covering the domains of existence of changes in the vicinity of the two phase transitions detected by DSC measurement. A detailed study of the spectral parameters (wave number, reduced intensity and the full width at half maximum) as a function of temperature of a chosen band, associated with (νs(Snsbnd O) + νs(Snsbnd Cl)), based on an order-disorder model allowed us to obtain information relative to the activation energy and correlation length.

  6. Synthesis and structure of [C 6H 14N 2][(UO 2) 4(HPO 4) 2(PO 4) 2(H 2O)]·H 2O: An expanded open-framework amine-bearing uranyl phosphate

    NASA Astrophysics Data System (ADS)

    Bray, Travis H.; Gorden, John D.; Albrecht-Schmitt, Thomas E.

    2008-09-01

    A new open-framework compound, [C 6H 14N 2][(UO 2) 4(HPO 4) 2(PO 4) 2(H 2O)]·H 2O, ( DUP-1) has been synthesized under mild hydrothermal conditions. The resulting structure consists of diprotonated DABCOH 22+ (C 6H 14N 22+) cations and occluded water molecules occupying the channels of a complex uranyl phosphate three-dimensional framework. The anionic lattice contains uranophane-like sheets connected by hydrated pentagonal bipyramidal UO 7 units. [C 6H 14N 2][(UO 2) 4(HPO 4) 2(PO 4) 2(H 2O)]·H 2O possesses five crystallographically unique U centers. U(VI) is present here in both six- and seven-coordinate environments. The DABCOH 22+ cations are held within the channels by hydrogen bonds to both two uranyl oxygen atoms and a μ2-O atom. Crystallographic data (193 K, Mo Kα, λ=0.71073 Å): DUP-1, monoclinic, P2 1/ n, a=7.017(1) Å, b=21.966(4) Å, c=17.619(3) Å, β=90.198(3)°, Z=4, R(F)=4.76% for 382 parameters with 6615 reflections with I>2 σ( I).

  7. Synthesis and crystal structure of oxalato-bridged dicopper(II) complex with hydrogen bonds [Cu 2(μ-C 2O 4)(bpy) 2(H 2O) 2(NO 3) 2

    NASA Astrophysics Data System (ADS)

    Tang, Jinkui; Gao, Enqing; Bu, Weiming; Liao, Daizheng; Yan, Shiping; Jiang, Zonghui; Wang, Genglin

    2000-07-01

    A new dicopper(II) complex [Cu 2(μ-C 2O 4)(bpy) 2(H 2O) 2(NO 3) 2] ( 1) has been synthesized and its structure determined (bpy=2,2'-bipyridine). The structure consists of centrosymmetric [Cu 2(μ-C 2O 4)(bpy) 2(H 2O) 2(NO 3) 2] molecules with each Cu(II) ion in a distorted octahedral environment: two nitrogen atoms from bpy, two oxygen atoms from the oxalate ion in the basal plane and two oxygen atoms from H 2O and the nitrato group in the two axial positions. The unusual ligand arrangement in ( 1) and the packing of molecules are attributed to intermolecular and intramolecular hydrogen bonding. The intermolecular and intramolecular hydrogen bonding formed a hydrogen bond plane and the intermolecular hydrogen bonding gave rise to a zigzag chain structure. The e.p.r. study of the polycrystalline powder at 110 K gives g⊥=2.04 and g∥=2.20, typical of axially elongated copper(II) systems, and the appearance of the half-field signals suggests a magnetic interaction between the two Cu(II) ions.

  8. Crystal structure, spectroscopic, magnetic and electronic structure studies of a novel Cu(II) amino acid complex [Cu(L-arg)2(H2O)]2(P4O12)·8H2O

    NASA Astrophysics Data System (ADS)

    Hemissi, H.; Nasri, M.; Abid, S.; Al-Deyab, S. S.; Dhahri, E.; Hlil, E. K.; Rzaigui, M.

    2012-12-01

    Single crystals of a novel copper (II) complex with the amino acid L-arginine (L-arg) and cyclotetraphosphate, [Cu(L-arg)2(H2O)]2(P4O12)·8H2O, were prepared in aqueous solution and were characterized by X-ray diffraction, spectroscopy (diffuse reflectance, UV-vis and IR) and thermal analysis. Magnetic measurements and electronic structure calculations were also performed. Crystal structure determination reveals that this compound has a nonsymmetrical atomic arrangement, containing mainly a binuclear [Cu(L-arg)2(H2O)]24+ cation and an uncoordinated cyclotetraphosphate counter-anion (P4O124-). The tetravalent cation contains two independent Cu(II) ions in two different chemical environments. This compound exhibits an antiferromagnetic (AFM) to paramagnetic (PM) phase transition at a temperature (TN) lower than 2 K. The values of paramagnetic Curie-Weiss temperature (θcw) and the exchange parameter (J/KB) emphasize the existence of an antiferromagnetic interaction between the neighboring copper ions.

  9. Effect of chirality on the dynamics of domain walls in the molecular ferrimagnet [MnII(H L-pn)(H2O)][MnIII(CN)6] · 2H2O

    NASA Astrophysics Data System (ADS)

    Mushenok, F. B.; Morgunov, R. B.; Koplak, O. V.; Kirman, M. V.

    2012-04-01

    The contributions from modes of switching, sliding, creep, and Debye relaxation of pinned domain walls to the low-frequency magnetic properties of the chiral and racemic molecular ferrimagnets [MnII(H L-pn)(H2O)][MnIII(CN)6] · 2H2O have been separated. It has been found that the chirality of the atomic and spin structures affects the temperatures of the transitions from the sliding mode to the creep mode and from the creep mode to the mode of Debye relaxation. In the chiral crystals, transitions to the creep and Debye relaxation modes have been observed at temperatures T = 7 and 5 K, respectively. In the racemic crystals, these transitions have been observed at temperatures T = 13 and 9 K, respectively, all other factors being equal.

  10. Experimental investigation of the EPR parameters and molecular orbital bonding coefficients for VO2+ ion in NaH2PO4·2H2O single crystals

    NASA Astrophysics Data System (ADS)

    Kalfaoğlu, Emel; Karabulut, Bünyamin

    2016-09-01

    Electron paramagnetic resonance (EPR) spectra of VO2+ ions in NaH2PO4·2H2O single crystal have been studied. The spin-Hamiltonian parameters and molecular orbital bonding coefficients were calculated. The angular variation of the EPR spectra shows two different VO2+ complexes. These are located in different chemical environment and each environment contains four magnetically inequivalent VO2+ sites. The crystal field around VO2+ ion is approximately axially symmetric since a strong V=O bond distorts the crystal lattice. Spin Hamiltonian parameters and molecular orbital bonding coefficients were calculated from the EPR data and the nature of bonding in the complex was discussed together.

  11. Transitions between quantum states of the spin-soliton structure in molecular magnets [Mn{( R/ S)- pn}]2[Mn{( R/ S)- pn}2(H2O)][Cr(CN)6]2

    NASA Astrophysics Data System (ADS)

    Morgunov, R. B.; Kirman, M. V.; Talantsev, A. D.

    2015-08-01

    A series of jumps of the magnetic moment (up to five jumps) with an amplitude of 1-10% of the saturation magnetization has been observed upon demagnetizing the molecular magnet [Mn{( R/ S)- pn}]2[Mn{( R/ S)- pn}2(H2O)][Cr(CN)6]2 in a narrow region of magnetic fields close to the coercive force. A decrease in the temperature leads to an increase in the critical magnetic field, which corresponds to the onset of the series of demagnetization jumps. The obtained experimental data agree with theoretical predictions on jump-like transitions between the magnetization curves upon attaining critical magnetic fields caused by the energy quantization of spin solitons.

  12. Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

    PubMed Central

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

  13. Crystal structure, thermal studies, Hirshfeld surface analysis, vibrational and DFT investigation of organic-inorganic hybrid compound [C9H6NOBr2]2CuBr4·2H2O

    NASA Astrophysics Data System (ADS)

    Mesbeh, Radhia; Hamdi, Besma; Zouari, Ridha

    2016-12-01

    Single crystals of a hybrid organic/inorganic material with the formula [C9H6NOBr2]2CuBr4·2H2O were studied by X-ray diffraction. The compound crystallizes in the monoclinic system, space group C2/c with the following unit cell parameters: a = 7.8201 (12) Ǻ, b = 18.203 (3) Ǻ, c = 19.486 (3) Ǻ, β = 98.330 (5)°, Z = 4, V = 2744.6 (7) Ǻ3. Crystal structure was solved with a final R = 5.66% for 3483 independent reflections. The atomic arrangement shows an alternation of organic and inorganic layers. Between layers, the cohesion is performed via Osbnd H⋯Br, Csbnd H⋯Br, Nsbnd H⋯Br, Nsbnd H⋯O and Osbnd H⋯O hydrogen bending. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements have been carried out on [C9H6NOBr2]2CuBr4·2H2O crystal in the temperature range between 50 and 500 °C. The assignment of the observed bands in the solid state FTIR and Raman spectra of the compound was assisted by the theoretically predicted frequencies and compared with data previously reported for similar compounds. The theoretical geometrical parameters in the ground state have been investigated by density functional theory (DFT) with the B3LYP/LanL2DZ level of theory. The optical properties were investigated by optical absorption and show two bands at 279, 300 nm. The percentages of hydrogen bonding interactions are analyzed by Fingerprint plots of Hirshfeld surface.

  14. Oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system up to 0.7 mol/kg ionic strength at 25 °C

    USGS Publications Warehouse

    Kim, Sang-Tae; Gebbinck, Christa Klein; Mucci, Alfonso; Coplen, Tyler B.

    2014-01-01

    To investigate the oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system, witherite (BaCO3) was precipitated quasi-instantaneously and quantitatively from Na-Cl-Ba-CO2 solutions of seawater-like ionic strength (I = 0.7 mol/kg) at two pH values (~7.9 and ~10.6) at 25 °C. The oxygen isotope composition of the witherite and the dissolved inorganic carbon speciation in the starting solution were used to estimate the oxygen isotope fractionations between HCO3¯ and H2O as well as between CO3 2 and H2O. Given the analytical error on the oxygen isotope composition of the witherite and uncertainties of the parent solution pH and speciation, oxygen isotope fractionation between NaHCO3° and HCO3¯, as well as between NaCO3¯ and CO3 2, is negligible under the experimental conditions investigated. The influence of dissolved NaCl concentration on the oxygen isotope fractionation in the aragonite-CO2-H2O-NaCl system also was investigated at 25 °C. Aragonite was precipitated from Na-Cl-Ca-Mg-(B)-CO2 solutions of seawater-like ionic strength using passive CO2 degassing or constant addition methods. Based upon our new experimental observations and published experimental data from lower ionic strength solutions by Kim et al. (2007b), the equilibrium aragonite-water oxygen isotope fractionation factor is independent of the ionic strength of the parent solution up to 0.7 mol/kg. Hence, our study also suggests that the aragonite precipitation mechanism is not affected by the presence of sodium and chloride ions in the parent solution over the range of concentrations investigated.

  15. U(IV)/Ln(III) mixed site in polymetallic oxalato complexes. Part III: Structure of Na[Yb(C 2O 4) 2(H 2O)]·3H 2O and the derived quadratic series (NH 4+) 1-x[ Ln1-xU x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, Pr-Sm, Gd, Tb

    NASA Astrophysics Data System (ADS)

    Chapelet-Arab, B.; Duvieubourg, L.; Nowogrocki, G.; Abraham, F.; Grandjean, S.

    2006-12-01

    Single crystals of a new sodium ytterbium oxalate Na[Yb(C 2O 4) 2(H 2O)]·3H 2O ( 1) and six mixed lanthanide (III)-uranium (IV) oxalates (NH 4+) 1-x[ Ln1-xU x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, x=0.47 ( 2), Ln=Pr, x=0.42 ( 3), Ln=Nd, x=0.60 ( 4), Ln=Sm, x=0.55 ( 5), Ln=Gd, x=0.25 ( 6) and Ln=Tb, x=0.52 ( 7) have been grown using slow diffusion through silica gels. The crystal structures of all the compounds have been determined by single-crystal X-ray diffraction. For compound 1 the symmetry is monoclinic, space group Pc, cell dimensions a=8.559(2) Å, b=8.564(2) Å, c=14.938(3) Å, β=103.062(3), Z=4. The structure of 1 is isotypic with Na[Y(C 2O 4) 2(H 2O)]·3H 2O and consists of layers formed by four-membered rings of Yb connected through oxalate ions. The ytterbium atom is nine-coordinated by oxygen from four bis-bidentate oxalate ligands and one water molecule which alternate up and down the layer. Na + ions and supplementary water molecules are located between the layers. The six mixed lanthanide (III)-uranium (IV) oxalates, 2- 7, are isotypic, the symmetry is tetragonal, space group P4/ n, the unit cell parameters are in the range 8.7239(12)-8.9116(6) and 7.854(2)-7.9487(9) Å for a and c, respectively, Z=2. The structure of the six compounds is built from the same two-dimensional arrangement of alternating metallic and oxalate ions forming four-membered rings. The layers are similar to that observed in 1 and the mixed Ln(III)/U(IV) oxalate layers are obtained by partial substitution of Ln(III) by U(IV) in a nine-coordinated site, the charge surplus being compensated by removal of monovalent cations in the interlayer space. The ammonium ions and the water molecules are disordered in the same crystallographic site. Thus these compounds form the third series of mixed lanthanide (III)-uranium (IV) oxalates, the tetragonal one, that completes the two others previously reported, the hexagonal and the triclinic series.

  16. Unusual Recognition and Separation of Hydrated Metal Sulfates [M2(μ-SO4)2(H2O)n, M = Zn(II), Cd(II), Co(II), Mn(II)] by a Ditopic Receptor.

    PubMed

    Ghosh, Tamal Kanti; Dutta, Ranjan; Ghosh, Pradyut

    2016-04-01

    A ditopic receptor L1, having metal binding bis(2-picolyl) donor and anion binding urea group, is synthesized and explored toward metal sulfate recognition via formation of dinuclear assembly, (L1)2M2(SO4)2. Mass spectrometric analysis, (1)H-DOSY NMR, and crystal structure analysis reveal the existence of a dinuclear assembly of MSO4 with two units of L1. (1)H NMR study reveals significant downfield chemical shift of -NH protons of urea moiety of L1 selectively with metal sulfates (e.g., ZnSO4, CdSO4) due to second-sphere interactions of sulfate with the urea moiety. Variable-temperature (1)H NMR studies suggest the presence of intramolecular hydrogen bonding interaction toward metal sulfate recognition in solution state, whereas intermolecular H-bonding interactions are observed in solid state. In contrast, anions in their tetrabutylammonium salts fail to interact with the urea -NH probably due to poor acidity of the tertiary butyl urea group of L1. Metal sulfate binding selectivity in solution is further supported by isothermal titration calorimetric studies of L1 with different Zn salts in dimethyl sulfoxide (DMSO), where a binding affinity is observed for ZnSO4 (Ka = 1.23 × 10(6)), which is 30- to 50-fold higher than other Zn salts having other counteranions in DMSO. Sulfate salts of Cd(II)/Co(II) also exhibit binding constants in the order of ∼1 × 10(6) as in the case of ZnSO4. Positive role of the urea unit in the selectivity is confirmed by studying a model ligand L2, which is devoid of anion recognition urea unit. Structural characterization of four MSO4 [M = Zn(II), Cd(II), Co(II), Mn(II)] complexes of L1, that is, complex 1, [(L1)2(Zn)2(μ-SO4)2]; complex 2, [(L1)2(H2O)2(Cd)2(μ-SO4)2]; complex 3, [(L1)2(H2O)2(Co)2(μ-SO4)2]; and complex 4, [(L1)2(H2O)2(Mn)2(μ-SO4)2], reveal the formation of sulfate-bridged eight-membered crownlike binuclear complexes, similar to one of the concentration-dependent dimeric forms of MSO4 as observed in solid state

  17. The effect of carbonic anhydrase on the kinetics and equilibrium of the oxygen isotope exchange in the CO2-H2O system: Implications for δ18O vital effects in biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Uchikawa, Joji; Zeebe, Richard E.

    2012-10-01

    Interpretations of the primary paleoceanographic information recorded in stable oxygen isotope values (δ18O) of biogenic CaCO3 can be obscured by disequilibrium effects. CaCO3 is often depleted in 18O relative to the δ18O values expected for precipitation in thermodynamic equilibrium with ambient seawater as a result of vital effects. Vital effects in δ18O have been explained in terms of the influence of fluid pH on the overall δ18O of the sum of dissolved inorganic carbon (DIC) species (often referred to as "pH model") and in terms of 18O depletion as a result of the kinetic effects associated with CO2 hydration (CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+) and CO2 hydroxylation (CO2 + OH- ↔ HCO3-) in the calcification sites (so-called "kinetic model"). This study addresses the potential role of an enzyme, carbonic anhydrase (CA), that catalyzes inter-conversion of CO2 and HCO3- in relation to the underlying mechanism of vital effects. We performed quantitative inorganic carbonate precipitation experiments in order to examine the changes in 18O equilibration rate as a function of CA concentration. Experiments were performed at pH 8.3 and 8.9. These pH values are comparable to the average surface ocean pH and elevated pH levels observed in the calcification sites of some coral and foraminiferal species, respectively. The rate of uncatalyzed 18O exchange in the CO2-H2O system is governed by the pH-dependent DIC speciation and the kinetic rate constant for CO2 hydration and hydroxylation, which can be summarized by a simple mathematical expression. The results from control experiments (no CA addition) are in agreement with this expression. The results from control experiments also suggest that the most recently published kinetic rate constant for CO2 hydroxylation has been overestimated. When CA is present, the 18O equilibration process is greatly enhanced at both pH levels due to the catalysis of CO2 hydration by the enzyme. For example, the time required for 18O

  18. The influence of temperature (20-1000 °C) on binary mixtures of solid solutions of CH 3COOLi·2H 2O-MgHPO 4·3H 2O

    NASA Astrophysics Data System (ADS)

    Umbreit, Michał H.; Paukszta, Dominik

    2009-11-01

    Thermally induced phase transitions (20-1000 °C) in the substrates and binary mixtures of CH 3COOLi·2H 2O(1)-MgHPO 4·3H 2O(11) have been analysed. Changes taking place on dehydration and thermal dissociation of binary mixtures prepared with percent molar ratios of 90-10% were studied by differential thermal analysis (TG, DTG, DTA), IR-spectroscopy and WAXS. The above-mentioned substrates changed their structure when heated for 1 h at 500 or 1000 °C. CH 3COOLi·2H 2O(1) (ID: 23-1171) changed the structure at 500 °C to that of Li 2CO 3 (ID: 22-1141), while at 1000 °C the structure was impossible to analyse as the compound reacted both with porcelain and with platinum (crucible materials). MgHPO 4·3H 2O(11) (Newberyite, ID: 35-780, 19-762) changed its structure at 500 °C to amorphous phase and at 1000 °C to Mg 2P 2O 7 (ID: 32-626). The following compounds were assayed in the respective binary mixtures heated at 500 °C for 1 h: 70% (1)-30%(11): LiMgPO 4 (ID: 18-735), MgO (ID: 4-829); 50%(1)-50%(11): LiMgPO 4 (ID: 18-735), Li 3PO 4 (ID: 25-1030); 30%(1)-70%(11): LiMgPO 4 (ID: 32-574); binary mixtures heated at 1000 °C contained the following compounds: 70%(1)-30%(11): LiMgPO 4 (ID: 32-574,18-735), Li 3PO 4 (ID: 15-760,25-1030), MgO (ID: 4-829); 50%(1)-50%(11): LiMgPO 4 (ID: 32-574, 18-735), MgO (ID: 4-829); 30%(1)-70%(11): LiMgPO 4 (ID: 18-735, 32-574), Mg 2P 2O 7 (ID: 22-1152, 8-38), Li 4SiO 4 (37-1472).

  19. Emerging micropollutant oxidation during disinfection processes using UV-C, UV-C/H2O2, UV-A/TiO2 and UV-A/TiO2/H2O2.

    PubMed

    Pablos, Cristina; Marugán, Javier; van Grieken, Rafael; Serrano, Elena

    2013-03-01

    Regeneration of wastewater treatment plant effluents constitutes a solution to increase the availability of water resources in arid regions. Water reuse legislation imposes an exhaustive control of the microbiological quality of water in the operation of disinfection tertiary treatments. Additionally, recent reports have paid increasing attention to emerging micropollutants with potential biological effects even at trace level concentration. This work focuses on the evaluation of several photochemical technologies as disinfection processes with the aim of simultaneously achieving bacterial inactivation and oxidation of pharmaceuticals as examples of emerging micropollutants typically present in water and widely studied in the literature. UV-C-based processes show a high efficiency to inactivate bacteria. However, the bacterial damages are reversible and only when using H(2)O(2), bacterial reproduction is affected. Moreover, a complete elimination of pharmaceutical compounds was not achieved at the end of the inactivation process. In contrast, UV-A/TiO(2) required a longer irradiation time to inactivate bacteria but pharmaceuticals were completely removed along the process. In addition, its oxidation mechanism, based on hydroxyl radicals (OH), leads to irreversible bacterial damages, not requiring of chemicals to avoid bacterial regrowth. For UV-A/TiO(2)/H(2)O(2) process, the addition of H(2)O(2) improved Escherichia coli inactivation since the cell wall weakening, due to OH attacks, allowed H(2)O(2) to diffuse into the bacteria. However, a total elimination of the pharmaceuticals was not achieved during the inactivation process. PMID:23276426

  20. Study of a series of cobalt(II) sulfonamide complexes: Synthesis, spectroscopic characterization, and microbiological evaluation against M. tuberculosis. Crystal structure of [Co(sulfamethoxazole)2(H2O)2]·H2O

    NASA Astrophysics Data System (ADS)

    Mondelli, Melina; Pavan, Fernando; de Souza, Paula C.; Leite, Clarice Q.; Ellena, Javier; Nascimento, Otaciro R.; Facchin, Gianella; Torre, María H.

    2013-03-01

    Nowadays, the research for new and better antimicrobial compounds is an important field due to the increase of immunocompromised patients, the use of invasive medical procedures and extensive surgeries, among others, that can affect the incidence of infections. Another big problem associated is the occurrence of drug-resistant microbial strains that impels a ceaseless search for new antimicrobial agents. In this context, a series of heterocyclic-sulfonamide complexes with Co(II) was synthesized and characterized with the aim of obtaining new antimicrobial compounds. The structural characterization was performed using different spectroscopic methods (UV-Vis, IR, and EPR). In spite of the fact that the general stoichiometry for all the complexes was Co(sulfonamide)2·nH2O, the coordination atoms were different depending on the coordinated sulfonamide. The crystal structure of [Co(sulfamethoxazole)2(H2O)2]·H2O was obtained by X-ray diffraction showing that Co(II) is in a slightly tetragonal distorted octahedron where sulfamethoxazole molecules act as a head-to-tail bridges between two cobalt atoms, forming polymeric chains. Besides, the activity against Mycobacterium tuberculosis, one of the responsible for tuberculosis, and the cytotoxicity on J774A.1 macrophage cells were evaluated.

  1. Synthesis, crystal structures, and characterization of double complex salts [Au(en)2][Rh(NO2)6]·2H2O and [Au(en)2][Rh(NO2)6

    NASA Astrophysics Data System (ADS)

    Plyusnin, Pavel E.; Makotchenko, Evgenia V.; Shubin, Yury V.; Baidina, Iraida A.; Korolkov, Ilya V.; Sheludyakova, Liliya A.; Korenev, Sergey V.

    2015-11-01

    Double complex salts of rhodium(III) and gold(III) of the composition [Au(en)2][Rh(NO2)6]·2H2O (1) and [Au(en)2][Rh(NO2)6] (2) have been prepared. Crystal structures of the compounds have been determined by single crystal X-ray diffraction. The compounds have been characterized by PXRD, IR, far-IR, CHN and DTA. The complexes have a layered structures. The presence of water in 1 makes the structure of the hydrated DCS less dense as compared to the anhydrous one. The environment of the cation and the anion in the two structures is the same, oxygen atoms of the nitro groups are involved in hydrogen bonds N-H⋯O, N⋯O distances being approximately the same. The structures of 1 and 2 are notable in having shortened contacts between the gold atoms and the oxygen atoms of the nitro groups of the neighboring complex anions. The thermal behavior of the complexes in a hydrogen atmosphere was investigated. The final product of thermolysis prepared at the temperature 600°C is a two-phase mixture of pure metallic gold and the solid solution Rh0.93Au0.07.

  2. Solvent effects on the relative stability of the PdCl2(H2O)n and PdHCl(H2O)n cis and trans isomers

    NASA Astrophysics Data System (ADS)

    Siegbahn, Per E. M.

    The relative stability of the cis and trans isomers of the PdCl2(H2O)n and PdHCl(H2O)n complexes with up to six water ligands has been studied. Optimized geometries are discussed with particular emphasis on the positions taken by the second sphere water ligands. It is found that the empty coordination site above palladium is not as attractive for the second sphere ligands as might have been anticipated. Two types of hydrogen bonds, of O-H...Pd and O-H...H-Pd were found, which have only recently been detected experimentally. The effect of a water solvent on the complexes was then studied using a model with a spherical cavity surrounded by a dielectric continuum. Since the cis forms of the complexes have large dipole moments, the dipole term of the solvent reaction field strongly favours these structures. However, it is found that the quadrupolar terms have an almost equally large effect in the opposite direction, favouring the trans isomer. Even the octapole and hexadecapole moments make non-negligible contributions to the relative stabilities.

  3. Resonance local phonon mode and electron spin-lattice relaxation of formate-type free radicals studied by electron spin echo in Cd(HCOO)2·2H2O crystal

    NASA Astrophysics Data System (ADS)

    Hoffmann, S. K.; Goslar, J.

    2015-07-01

    The results of X-band electron spin resonance (ESR) and electron spin echo (ESE) measurements for free radicals generated in Cd(HCOO)2·2H2O single crystal are presented. From ESR spectra analysis the radicals were identified as \\text{CO}2- after x-ray irradiation and as HOCO after γ-ray irradiation. The room temperature g-factors are: g|| = 1.9969 and g⊥ = 2.0024 for \\text{CO}2- and g1 = 2.0087, g2 = 2.0029 and g3 = 1.9960 for HOCO. Axial g-tensor symmetry for \\text{CO}2- is due to fast reorientation of the radical molecule around the g||-axis. Assignment of HOCO is confirmed by hyperfine splitting (Amax = 0.4 mT) from a single distant proton. Spin lattice relaxation rate was determined from ESE measurements in temperature range 4-250 K. Both radicals relax via local resonance mode lying within acoustic phonon branch. The existing theories of electron spin-lattice relaxation via local resonance mode are critically reviewed and compared with experimental data. A new approximation is proposed giving local mode energy \\hbar {ωR} = 56 cm-1 for \\text{CO}2- and \\hbar {ωR} = 44 cm-1 for the HOCO-radical.

  4. KNa 3(UO 2) 2(Si 4O 10) 2(H 2O) 4, a new compound formed during vapor hydration of an actinide-bearing borosilicate waste glass

    NASA Astrophysics Data System (ADS)

    Burns, Peter C.; Olson, Rudolph A.; Finch, Robert J.; Hanchar, John M.; Thibault, Yves

    2000-02-01

    Vapor hydration experiments on a U-doped borosilicate waste glass at 200°C produced a novel uranium silicate. Single crystal X-ray structure analysis of this phase indicate the ideal formula KNa 3(UO 2) 2(Si 4O 10) 2(H 2O) 4, although the compound shows some compositional variability. It is monoclinic, space group C2, Z=2, a=1.2782(1) , b=1.3654(1), c=0.82677(8) nm, β=119.240(1)°. The structure was solved by direct methods and refined to an agreement index ( R) of 3.6% for 2239 unique observed (| F0|⩾4 σF) reflections and a goodness-of-fit of 1.05. The structure contains vertex-sharing silicate tetrahedra arranged in four and eight-membered rings that are linked to give sheets parallel to (0 0 1). The sheets are cross-linked by vertex-sharing with UrO 4 square bipyramids [Ur=(UO 2) 2+ uranyl ion], forming a framework of polyhedra of higher bond-valence. The title phase is the major sink for U during glass corrosion at 200°C after approximately 60 days in a saturated vapor environment. Consideration of the structural sites reveals the potential of this compound to incorporate radionuclides from a variety of nuclear-waste glasses over a wide range of environmental conditions.

  5. Repetitively pulsed atmospheric pressure discharge treatment of rough polymer surfaces: II. Treatment of micro-beads in He/NH3/H2O and He/O2/H2O mixtures

    NASA Astrophysics Data System (ADS)

    Bhoj, Ananth N.; Kushner, Mark J.

    2008-08-01

    Plasmas are increasingly being used to functionalize the surface of polymers having complex shapes for biomedical applications such as tissue scaffolds and drug delivering micro-beads. The functionalization often requires affixation of amine (NH2) or O-containing groups. In this paper, results are discussed from a two-dimensional computational investigation of the atmospheric pressure plasma functionalization of non-planar and porous surfaces of polypropylene with NHx and O-containing groups. For the former, the discharge is sustained in He/NH3/H2O mixtures in a dielectric barrier-corona configuration. Significant microscopic non-uniformities arise due to competing pathways for reactive gas phase radicals such as OH and NH2, and on the surface by the availability of OH to initiate amine attachment. The treatment of inside surfaces of porous polymer micro-beads placed on an electrode is particularly sensitive to view angles to the discharge and pore size, and is ultimately controlled by the relative rates of radical transport and surface reactions deep into the pores. The functionalization of micro-beads suspended in He/O2/H2O discharges is rapid with comparable treatment of the outer and interior surfaces, but varies with the location of the micro-bead in the discharge volume.

  6. Two-Step Photon Absorption Driving the Chemical Reaction in the Model Ruthenium Nitrosyl System [Ru(py)4Cl(NO)](PF6)2·(1)/2H2O.

    PubMed

    Khadeeva, Liya; Kaszub, Wawrzyniec; Lorenc, Maciej; Malfant, Isabelle; Buron-Le Cointe, Marylise

    2016-05-01

    Various systems containing the [ML5NO] molecule, where M = Fe, Ru, ... and L = F, Cl, ..., exhibit switching under continuous light (CW) irradiation between the ground-state nitrosyl (GS), isonitrosyl (MSI), and side-on (MSII) configurations. The metastable populations, however, are often limited to a few percent. The [Ru(py)4Cl(NO)](PF6)2·(1)/2H2O system is thus a remarkable model compound as the GS to MSI transformation is nearly complete in a single crystal. A predominant two-step photon absorption process during GS to MSI switching under blue light is revealed by visible absorption spectroscopy, although a low concentration of the transient species hinders the determination of this process by the structural signature. During the depopulation of MSI, both two-step and direct processes are evidenced under red CW irradiation. Different intermediate visible spectra revealing transient species during GS to MSI and the reverse photochemical processes are discussed in relation to MSII properties. PMID:27054377

  7. Synthesis and structural characterization of metal-organic frameworks with the mellitate linker M2(OH)2[C12O12H2]·2H2O (M = Al, Ga, In) MIL-116

    NASA Astrophysics Data System (ADS)

    Volkringer, Christophe; Loiseau, Thierry; Guillou, Nathalie; Férey, Gérard; Popov, Dmitry; Burghammer, Manfred; Riekel, Christian

    2013-12-01

    A new series of isostructural MOF-type carboxylates called MIL-116 (M2(OH)2[C12O12H2]·2H2O), was synthesized from the combination of mellitic acid and trivalent p cations M = Al3+, Ga3+ or In3+. Their structures were analyzed either by single-crystal microdiffraction using the synchrotron radiation beamline (ID13 station at ESRF, Grenoble) or solved from powder X-ray diffraction. The 3D hybrid framework is built up from the connection of infinite straight chains of metal-centered octahedra sharing trans corners linked to each other through the mellitate ligands. Here the ligand acts as octadentate linker with four of the carboxylic groups involved in the M-O-C bondings. The two other carboxylate arms remain non-bonded under their protonated form. This represents a rare case of the occurrence of both non-bonding and bonding organic functionalities in a MOF-type solid. Within the tunnels are located water species that interact with the non-coordinated -COOH groups pointing towards the channel.

  8. Hydrothermal synthesis and structural characterization of Zn(II)- and Cd(II)-pyridine-2,3-dicarboxylate 2D coordination polymers, {(NH 4) 2[M(μ-pydc) 2]·2H 2O} n

    NASA Astrophysics Data System (ADS)

    Çolak, Alper Tolga; Pamuk, Gönül; Yeşilel, Okan Zafer; Yüksel, Fatma

    2011-12-01

    In this study, two novel coordination polymers {(NH 4) 2[M(μ-pydc) 2]·2H 2O} n (M = Zn(II), 1 and Cd(II), 2) (H 2pydc = Pyridine-2,3-dicarboxylic acid or quinolinic acid) have been hydrothermally synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. It has been observed that 1 and 2 have crystallized in the monoclinic space group P2 1/n. The M(II) ions are coordinated by the tridentate pydc bridging ligand through the oxygen atom of the carboxylate groups and the nitrogen atom of the pyridine ring in a bidentate manner and the oxygen atoms of carboxylate groups of other pydc ligands forming a distorted octahedral geometry. X-ray single crystal structural analyses put forth that two-dimensional frameworks were formed, and were assembled into a three-dimensional supramolecular structure by intermolecular N-H⋯O and O-H⋯O hydrogen bonding interactions.

  9. Optical emission spectroscopy study of premixed C2H4/O2 and C2H4/C2H2/O2 flames for diamond growth with and without CO2 laser excitation

    NASA Astrophysics Data System (ADS)

    He, X. N.; Gebre, T.; Shen, X. K.; Xie, Z. Q.; Zhou, Y. S.; Lu, Y. F.

    2010-02-01

    Optical emission spectroscopy (OES) measurements were carried out to study premixed C2H4/O2 and C2H4/C2H2/O2 combustion flame for diamond deposition with and without a CO2 laser excitation. Strong emissions from radicals C2 and CH were observed in the visible range in all the OES spectra acquired. By adding a continuous-wave CO2 laser to irradiate the flame at a wavelength of 10.591 μm, the common CO2 laser wavelength, it was discovered that the emission intensities of the C2 and CH radicals were increased due to the laser beam induced excitation. OES measurements of the C2 and CH radicals were performed using different gas combinations and laser powers. The rotational temperatures in the flame were determined by analyzing the spectra of the R-branch of the A2Δ-->X2Π (0, 0) electronic transition near 430 nm (CH band head). Information obtained from the OES spectra, including the emission intensities of the C2 and CH radicals, the intensity ratios, and the rotational temperatures, was integrated into the study of diamond deposition on tungsten carbide substrates for mechanism analysis of the laser induced vibrational excitation and laser-assisted diamond deposition.

  10. Synthesis, crystal structure and third-order non-linear optical properties of a two-dimensional coordination network [Cd(AcO)2(L)2(H2O)

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao-Xia; Pan, Wei-Cheng; Hong, Peng-Zhi; Li, Ke-Chang; Li, Yong

    2015-02-01

    A novel two-dimensional (2-D) Cd(II) coordination network [Cd(AcO)2(L)2(H2O)] 1 (AcO = acetate, L = 4-(1,2,4-triazol-1-yl) benzoic acid ethyl ester) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and UV-visible spectra. The molecules of the complex are interconnected into layers by O-H⋯O and C-H⋯O hydrogen bonds in which participate AcO-, L and H2O ligands. The intermolecular hydrogen-bonds interactions are the most significant factors controlling the novel supramolecular sheet fashion packing of the title compound in the crystal state. The third-order non-linear optical (NLO) properties of the title compound 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 2.30 × 10-30 esu for 1 in a 2.15 × 10-4 mol dm-3 DMF solution.

  11. Near infrared diode laser spectroscopy of C2H2, H2O, CO2 and their isotopologues and the application to TDLAS, a tunable diode laser spectrometer for the martian PHOBOS-GRUNT space mission

    NASA Astrophysics Data System (ADS)

    Durry, G.; Li, J. S.; Vinogradov, I.; Titov, A.; Joly, L.; Cousin, J.; Decarpenterie, T.; Amarouche, N.; Liu, X.; Parvitte, B.; Korablev, O.; Gerasimov, M.; Zéninari, V.

    2010-04-01

    A near-infrared tunable diode laser spectrometer called TDLAS has been developed that combines telecommunication-type as well as new-generation antimonide laser diodes to measure C2H2, H2O, CO2 and their isotopologues in the near infrared. This sensor is devoted to the in situ analysis of the soil of the Martian satellite PHOBOS, within the framework of the Russian space mission PHOBOS-GRUNT. In the first part of the paper, we report accurate spectroscopic measurements of C2H2 and 13C12CH2 near 1.533 μm, of H2O and CO2 at 2.682 μm and of the isotopologues 13C16O2 and 16O12C18O near 2.041 μm and H2 17O, H2 18O and HDO near 2.642 μm. The achieved line strengths are thoroughly compared to data from molecular databases or from former experimental determinations. In the second part of the paper, we describe the TDLAS spectrometer for the PHOBOS-GRUNT mission.

  12. Solubility-product constant and thermodynamic properties for synthetic otavite, CdCO3(s), and aqueous association constants for the Cd(II)-CO2-H2O system

    USGS Publications Warehouse

    Stipp, S.L.S.; Parks, George A.; Nordstrom, D.K.; Leckie, J.O.

    1993-01-01

    Considerable disparity exists in the published thermodynamic data for selected species in the Cd(II)-CO2-H2O system near 25??C and 1 atm pressure. Evaluation of published experimental and estimated data for aqueous cadmium-carbonate species suggests an association constant, pK, of -3.0 ?? 0.4 for CdCO30, about -1.5 for CdHCO3+, and -6.4 ?? 0.1 for Cd(CO3)22- (T = 298.15 K; P = 1 atm; I = 0). Examination of all available data for cadmium-hydrolysis species and ??-Cd(OH)2(s)) confirms that the consistent set of constants presented by Baes and Mesmer (Hydrolysis of Cations, 1976) is the best available. The solubility of synthetic otavite, CdCO3(s), has been measured in KClO4 solutions where I ??? 0.1 M. We calculated pKsp = 12.1 ?? 0.1 (T = 25.0??C; P = 1 atm; I = 0) from measured concentrations of Cd2+, measured PC02 and pH, our selected set of equilibrium constants, and activity corrections estimated using the Davies equation. Values at 5 and 50??C were 12.4 ?? 0.1 and 12.2 ?? 0.1, respectively. Based on the new solubility data and the CODATA key values for Cd2+ and CO32-, a new set of thermodynamic properties is recommended for otavite: ??Gf0 = -674.7 ?? 0.6 kJ/mol; ??Hf0 = -751.9 ?? 10 kJ/mol; S0 = 106 ?? 30 J/mol K; and ??Gr0 for the reaction Cd2+ + CO32- ??? CdCO3(s) is -69.08 ?? 0.57 kJ/m. ?? 1993.

  13. CO 2-H 2O mixtures in the geological sequestration of CO 2. I. Assessment and calculation of mutual solubilities from 12 to 100°C and up to 600 bar

    NASA Astrophysics Data System (ADS)

    Spycher, Nicolas; Pruess, Karsten; Ennis-King, Jonathan

    2003-08-01

    Evaluating the feasibility of CO 2 geologic sequestration requires the use of pressure-temperature-composition ( P- T- X) data for mixtures of CO 2 and H 2O at moderate pressures and temperatures (typically below 500 bar and below 100°C). For this purpose, published experimental P- T- X data in this temperature and pressure range are reviewed. These data cover the two-phase region where a CO 2-rich phase (generally gas) and an H 2O-rich liquid coexist and are reported as the mutual solubilities of H 2O and CO 2 in the two coexisting phases. For the most part, mutual solubilities reported from various sources are in good agreement. In this paper, a noniterative procedure is presented to calculate the composition of the compressed CO 2 and liquid H 2O phases at equilibrium, based on equating chemical potentials and using the Redlich-Kwong equation of state to express departure from ideal behavior. The procedure is an extension of that used by King et al. (1992), covering a broader range of temperatures and experimental data than those authors, and is readily expandable to a nonideal liquid phase. The calculation method and formulation are kept as simple as possible to avoid degrading the performance of numerical models of water-CO 2 flows for which they are intended. The method is implemented in a computer routine, and inverse modeling is used to determine, simultaneously, (1) new Redlich-Kwong parameters for the CO 2-H 2O mixture, and (2) aqueous solubility constants for gaseous and liquid CO 2 as a function of temperature. In doing so, mutual solubilities of H 2O from 15 to 100°C and CO 2 from 12 to 110°C and up to 600 bar are generally reproduced within a few percent of experimental values. Fugacity coefficients of pure CO 2 are reproduced mostly within one percent of published reference data.

  14. Synthesis, Crystal Structure, and Magnetic Properties of a Chiral Cyanide-Bridged Bimetallic Framework K3[Mn(II)(L-asp)]6[Cr(III)(CN)6]·2H2O.

    PubMed

    Li, Li; Nishihara, Sadafumi; Inoue, Katsuya; Kurmoo, Mohamedally

    2016-01-01

    All five coordinating atoms of the amino-acid dianion L-aspartate (L-asp = NH2CH(COO)CH2COO(2-)) are found to be involved in coordination with Mn(II) in the presence of [Cr(III)(CN)6](3-) to self-assemble into a chiral three-dimensional cyanide-bridged K3[Mn(L-asp)]6[Cr(CN)6]·2H2O containing the highest ratio of Mn:Cr of 6:1. It adopts the chiral P3 (no. 143) space group consisting of zigzag Mn-OCO-Mn chains sharing edges of hexagonal channels with central [Cr(CN)6](3-), while K(+) and H2O occupy another parallel star-shaped channel. Its magnetic susceptibility above 100 K is dominated by the nearest neighbor (Mn-Cr at 5.08 and 5.31 Å) antiferromagnetic (AF) exchange interactions (θ = -15(1) K) and below 40 K by further AF interaction between Mn and Mn at 5.32 Å. It finally reaches a steady value at 4.5 K, where a bifurcation of the zero-field-cooled and field-cooled magnetizations is observed in small fields (<1 kOe). The isothermal magnetization is linear in field and deviating toward saturation above 60 kOe at 2 K. No imaginary component of the ac susceptibilities is observed. This behavior is associated with long-range antiferromagnetic order of a helical or conic nature where the magnetic sublattices are numerous [2n × (6Mn + 1Cr)], leading to a domain of sufficient size to allow for the presence of the bifurcation. A model is proposed based on the local anisotropy and symmetry multiplicity of the space group. PMID:26671258

  15. Electrooxidation of Ethanol and Methanol Using the Molecular Catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10.).

    PubMed

    Liu, YuPing; Zhao, Shu-Feng; Guo, Si-Xuan; Bond, Alan M; Zhang, Jie; Zhu, Guibo; Hill, Craig L; Geletii, Yurii V

    2016-03-01

    Highly efficient electrocatalytic oxidation of ethanol and methanol has been achieved using the ruthenium-containing polyoxometalate molecular catalyst, [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-)). Voltammetric studies with dissolved and surface-confined forms of [1(γ-SiW10O36)2](10-) suggest that the oxidized forms of 1 can act as active catalysts for alcohol oxidation in both aqueous (over a wide pH range covering acidic, neutral, and alkaline) and alcohol media. Under these conditions, the initial form of 1 also exhibits considerable reactivity, especially in neutral solution containing 1.0 M NaNO3. To identify the oxidation products, preparative scale bulk electrolysis experiments were undertaken. The products detected by NMR, gas chromatography (GC), and GC-mass spectrometry from oxidation of ethanol are 1,1-diethoxyethane and ethyl acetate formed from condensation of acetaldehyde or acetic acid with excess ethanol. Similarly, the oxidation of methanol generates formaldehyde and formic acid which then condense with methanol to form dimethoxymethane and methyl formate, respectively. These results demonstrate that electrocatalytic oxidation of ethanol and methanol occurs via two- and four-electron oxidation processes to yield aldehydes and acids. The total faradaic efficiencies of electrocatalytic oxidation of both alcohols exceed 94%. The numbers of aldehyde and acid products per catalyst were also calculated and compared with the literature reported values. The results suggest that 1 is one of the most active molecular electrocatalysts for methanol and ethanol oxidation. PMID:26848832

  16. A thermodynamic model for di-trioctahedral chlorite from experimental and natural data in the system MgO-FeO-Al2O3-SiO2-H2O: applications to P- T sections and geothermometry

    NASA Astrophysics Data System (ADS)

    Lanari, Pierre; Wagner, Thomas; Vidal, Olivier

    2014-02-01

    We present a new thermodynamic activity-composition model for di-trioctahedral chlorite in the system FeO-MgO-Al2O3-SiO2-H2O that is based on the Holland-Powell internally consistent thermodynamic data set. The model is formulated in terms of four linearly independent end-members, which are amesite, clinochlore, daphnite and sudoite. These account for the most important crystal-chemical substitutions in chlorite, the Fe-Mg, Tschermak and di-trioctahedral substitution. The ideal part of end-member activities is modeled with a mixing-on-site formalism, and non-ideality is described by a macroscopic symmetric (regular) formalism. The symmetric interaction parameters were calibrated using a set of 271 published chlorite analyses for which robust independent temperature estimates are available. In addition, adjustment of the standard state thermodynamic properties of sudoite was required to accurately reproduce experimental brackets involving sudoite. This new model was tested by calculating representative P- T sections for metasediments at low temperatures (<400 °C), in particular sudoite and chlorite bearing metapelites from Crete. Comparison between the calculated mineral assemblages and field data shows that the new model is able to predict the coexistence of chlorite and sudoite at low metamorphic temperatures. The predicted lower limit of the chloritoid stability field is also in better agreement with petrological observations. For practical applications to metamorphic and hydrothermal environments, two new semi-empirical chlorite geothermometers named Chl(1) and Chl(2) were calibrated based on the chlorite + quartz + water equilibrium (2 clinochlore + 3 sudoite = 4 amesite + 4 H2O + 7 quartz). The Chl(1) thermometer requires knowledge of the (Fe3+/ΣFe) ratio in chlorite and predicts correct temperatures for a range of redox conditions. The Chl(2) geothermometer which assumes that all iron in chlorite is ferrous has been applied to partially recrystallized

  17. Esperanzaite, NaCa2Al2(As5+O4)2F4(OH)*2H2O, a new mineral species from the La Esperanza mine, Mexico: descriptive mineralogy and atomic arrangement

    USGS Publications Warehouse

    Foord, E.E.; Hughes, J.M.; Cureton, F.; Maxwell, C.H.; Falster, A.U.; Sommer, A.J.; Hlava, P.F.

    1999-01-01

    Esperanzaite, ideally NaCa2Al2(As5+O4)2F4(OH)??2H2O, Z = 2, is a new mineral species from the La Esperanza mine, Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm in diameter. The Mohs hardness is 4 1/2 , and the specific gravity, 3.24 (obs.) and 3.36(3) (calc.). Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), X = Y = Z = colorless, ?? 1.580(1), ?? 1.588(1), and ?? 1.593(1); 2V(obs) is 74(1)??and 2V(calc) is 76.3??. The dispersion is medium, r < v, and the optic axes are oriented according to a ?? Z = +50.5??, b = Y, c ?? X = +35??. The strongest five X-ray-diffraction maxima in the powder pattern [d in A??(I)(hkl)] are: 2.966(100)(131, 311, 031), 3.527(90)(220), 2.700(90)(221,002,040), 5.364(80)(001,020) and 4.796(80)(011). Esperanzaite is monoclinic, a 9.687(5), b 10.7379(6), c 5.5523(7) A??, ?? 105.32(1)??, space group P21/m. The atomic arrangement of esperanzaite was solved by direct methods and Fourier analysis (R = 0.032). The Fundamental Building Block (FBB) is formed of [001] stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedra and two Al octahedra, corner-linked in four-member rings. The FBBs are linked by irregular Na??5 and Ca??8 polyhedra.

  18. In-situ measurements of D/H fractionation between melt and coexisting aqueous fluids in the Na2O-Al2O3-SiO2-H2O system

    NASA Astrophysics Data System (ADS)

    Dalou, C.; Le Losq, C.; Mysen, B. O.

    2014-12-01

    Hydrogen isotope partitioning (as H2O and D2O) between water-saturated silicate melts and coexisting silicate-saturated aqueous fluids with several different initial D/H ratios in the Na2O-Al2O3-SiO2-H2O system has been determined. In-situ measurements in a hydrothermal diamond anvil cell (HDAC) with the fluid and melt at the desired temperatures (≤800˚C) and pressures (≤1115 MPa) were carried out with microRaman and FTIR spectroscopy techniques. For bulk D/H ratios were used: 0.05 ±0.02, 0.13 ±0.05, 0.53 ±0.01 and 2.35 ±0.04. Three experimental series (D/H: 0.05, 0.13, 0.53) with coexisting fluid and melt have comparable pressure/temperature trajectories (350-650 ºC/322-626, 313-741 and MPa; 248-648 MPa, respectively), whereas the experimental series with D/H=2.35 had a lower pressure/temperature trajectory (400-680 ºC/192-496 MPa). In these pressure/temperature ranges, the D/H ratios of fluids barely change with temperature, with an average small negative ΔHfluid -1.2 ±0.5 kJ/mol. In contrast, the D/H ratios of coexisting melts display strong temperature dependence. The ΔHmelt decreases from 14.6 ±2.2 to -3.7 ±1.1 kJ/mol with the D/H ratio increasing from 0.05 ±0.02 to 2.35 ±0.04. Consequently, the (D,H) exchange equilibrium between melt and fluid is temperature dependent, and varies so that its ΔH increases from -15.9 ±2.7 to 0.3 ±0.4 kJ/mol with increasing D/H ratios. Hydrogen isotope fractionation between silicate melts and low density phases (aqueous fluids or gases) may affect the δD values during, for example degassing of mantle derived-magmatic liquids. Moreover, D/H fractionation between silicate minerals and melts in the Earth's interior can be affected by the significant temperature and composition-dependent D/H fractionation in silicate melts at high temperatures and pressures.

  19. Electronic structure of the water oxidation catalyst cis,cis-[(bpy)2(H2O)Ru(III)ORu(III)(OH2)(bpy)2]4+, the blue dimer.

    PubMed

    Jurss, Jonah W; Concepcion, Javier J; Butler, Jennifer M; Omberg, Kristin M; Baraldo, Luis M; Thompson, Darla Graff; Lebeau, Estelle L; Hornstein, Brooks; Schoonover, Jon R; Jude, Hershel; Thompson, Joe D; Dattelbaum, Dana M; Rocha, Reginaldo C; Templeton, Joseph L; Meyer, Thomas J

    2012-02-01

    The first designed molecular catalyst for water oxidation is the "blue dimer", cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(OH(2))(bpy)(2)](4+). Although there is experimental evidence for extensive electronic coupling across the μ-oxo bridge, results of earlier DFT and CASSCF calculations provide a model with magnetic interactions of weak to moderately coupled Ru(III) ions across the μ-oxo bridge. We present the results of a comprehensive experimental investigation, combined with DFT calculations. The experiments demonstrate both that there is strong electronic coupling in the blue dimer and that its effects are profound. Experimental evidence has been obtained from molecular structures and key bond distances by XRD, electrochemically measured comproportionation constants for mixed-valence equilibria, temperature-dependent magnetism, chemical properties (solvent exchange, redox potentials, and pK(a) values), XPS binding energies, analysis of excitation-dependent resonance Raman profiles, and DFT analysis of electronic absorption spectra. The spectrum can be assigned based on a singlet ground state with specific hydrogen-bonding interactions with solvent molecules included. The results are in good agreement with available experimental data. The DFT analysis provides assignments for characteristic absorption bands in the near-IR and visible regions. Bridge-based dπ → dπ* and interconfiguration transitions at Ru(III) appear in the near-IR and MLCT and LMCT transitions in the visible. Reasonable values are also provided by DFT analysis for experimentally observed bond distances and redox potentials. The observed temperature-dependent magnetism of the blue dimer is consistent with a delocalized, diamagnetic singlet state (dπ(1)*)(2) with a low-lying, paramagnetic triplet state (dπ(1)*)(1)(dπ(2)*)(1). Systematic structural-magnetic-IR correlations are observed between ν(sym)(RuORu) and ν(asym)(RuORu) vibrational energies and magnetic properties in a series of

  20. Structural incorporation of As5+ into rhomboclase ((H5O2)Fe3+(SO4)2 · 2H2O) and (H3O)Fe(SO4)2.

    PubMed

    Bolanz, Ralph M; Göttlicher, Jörg; Steininger, Ralph; Wieczorek, Arkadiusz

    2016-03-01

    Iron sulfates represent an essential sink for the toxic element arsenic in arid and semi-arid mining areas with high evaporation rates. Information about the structural incorporation of As(5+) in iron sulfates, however, remains scarce. Here we present evidence for the heterogeneous substitution of S(6+) by As(5+) in the crystal structure of rhomboclase ((H5O2)Fe(3+)(SO4)2 · 2H2O) and its dehydration product (H3O)Fe(SO4)2. Rhomboclase (Rhc) was synthesized in the presence of As(5+) with molar As/Fe ratios of 0, 0.25, 0.5, 0.75 and 1.0, resulting in As loads of 0.0, 0.93, 1.44, 1.69 and 1.87 wt.%, respectively. The unit cell parameters of Rhc increase from 9.729(6), 18.303(2), and 5.432(1) Å for a, b, and c, to 9.745(9), 18.332(5), and 5.436(8) Å when Rhc is crystallized at a molar As/Fe ratio of 1. Simultaneously, the crystallite size decreased from 304 to 176 nm. In situ dehydration of Rhc to (H3O)Fe(SO4)2, investigated by powder X-ray diffraction, shows that Rhc starts to dehydrate at 76 °C, which is completed at 86 °C. The presence of As(5+) does not impact the start or end temperatures of Rhc dehydration but does accelerate the dehydration. X-ray absorption fine structure spectroscopy (EXAFS) reveals that S(6+), in the Rhc and (H3O)Fe(SO4)2 structure, is replaced by As(5+), while the polymerization of AsO4-tetrahedra and FeO6-octahedra during the formation of (H3O)Fe(SO4)2 results in a strong distortion of the AsO4-tetrahedron. PMID:26735735

  1. Carbonate mineral solubility at low temperatures in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system

    NASA Astrophysics Data System (ADS)

    Marion, Giles M.

    2001-06-01

    Carbonate minerals have played an important role in the geochemical evolution of Earth, and may have also played an important role in the geochemical evolution of Mars and Europa. Several models have been published in recent years that describe chloride and sulfate mineral solubilities in concentrated brines using the Pitzer equations. Few of these models are parameterized for subzero temperatures, and those that are do not include carbonate chemistry. The objectives of this work are to estimate Pitzer-equation bicarbonate-carbonate parameters and carbonate mineral solubility products and to incorporate them into the FREZCHEM model to predict carbonate mineral solubilities in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system at low temperatures (≤25°C) with a special focus on subzero temperatures. Most of the Pitzer-equation parameters and equilibrium constants are taken from the literature and extrapolated into the subzero temperature range. Solubility products for 14 sodium, potassium, magnesium, and calcium bicarbonate and carbonate minerals are included in the model. Most of the experimental data are at temperatures ≥ -8°C; only for the NaHCO 3-NaCl-H 2O and Na 2CO 3-NaCl-H 2O systems are there bicarbonate and carbonate data to temperatures as low as -21.6°C. In general, the fit of the model to the experimental data is good. For example, calculated eutectic temperatures and compositions for NaHCO 3, Na 2CO 3, and their mixtures with NaCl and Na 2SO 4 salts are in good agreement with experimental data to temperatures as low as -21.6°C. Application of the model to eight saline, alkaline carbonate waters give predicted pHs ranging from 9.2 to 10.2, in comparison with measured pHs that range from 8.7 to 10.2. The model suggests that the CaCO 3 mineral that precipitates during seawater freezing is probably calcite and not ikaite. The model demonstrates that a proposed salt assemblage for the icy surface of Europa consisting of highly hydrated MgSO 4

  2. Multiphoton ionization studies of clusters of immiscible liquids. II. C6H6- (H2O)n, n=3-8 and (C6H6)2- (H2O)1,2

    NASA Astrophysics Data System (ADS)

    Garrett, Aaron W.; Zwier, Timothy S.

    1992-03-01

    Resonant two-photon ionization (R2PI) time-of-flight mass spectroscopy is used to record S0-S1 spectra of the neutral complexes C6H6-(H2O)n with n=3-8 and (C6H6)2-(H2O)1,2. Due to limitations imposed by the size of these clusters, a number of vibronic level arguments are used to constrain the gross features of the geometries of these clusters. Among the spectral clues provided by the data are the frequency shifts of the transitions, their van der Waals structure, the fragmentation of the photoionized clusters, and the complexation-induced origin intensity and 610 splitting. In the 1:3 cluster, simple arguments are made based on the known structures of the 1:1 and 1:2 clusters which lead to the conclusion that all three water molecules reside on the same side of the benzene ring. Three structures for the 1:3 cluster are proposed which are consistent with the available data. Of these, only one is also consistent with the remarkable similarity of the 1:4 and 1:5 spectra to those of the 1:3 cluster. This structure involves a cyclic water trimer in which one of the water molecules is near the sixfold axis in a π hydrogen-bonded configuration. This structure is then expanded in the 1:4 and 1:5 clusters to incorporate the fourth and fifth water molecules in cyclic structures which place the additional water molecules far from the benzene ring without disturbing the interaction of the other water molecules with the benzene ring. For 1:n clusters with n≥6, subtle and then significant changes are observed in the spectra which indicate changes in the way the water cluster interacts with the benzene ring. This development occurs at precisely the water cluster size which calculations predict that cagelike water cluster structures will begin to compete and eventually be favored over large cyclic structures. Finally, cursory scans of the 2:1 cluster show that this cluster also fragments efficiently upon photoionization by loss of a single water molecule and that it possesses a

  3. Self-encapsulation of [MII(phen)2(H2O)2]2+ (M=Co, Zn) in one-dimensional nanochannels of [MII(H2O)6(BTC)2]4- (M=Co, Cu, Mn): a high HQ/CAT ratio catalyst for hydroxylation of phenols.

    PubMed

    Bi, Jianhong; Kong, Lingtao; Huang, Zixiang; Liu, Jinhuai

    2008-06-01

    Four novel three-dimensional (3D) microporous supramolecular compounds containing nanosized channels, namely, [Co(phen)2(H2O)2]2[Co(H2O)6].2BTC.21.5H2O (1), [Co(phen)2(H2O)2]2[Cu(H2O)6].2BTC.21.5H2O (2), [Co(phen)2(H2O)2]2[Mn(H2O)6].2BTC.18H2O (3), and [Zn(phen)2(H2O)2]2[Mn(H2O)6].2BTC.22.5H2O (4), were synthesized from 1,3,5-benzenetricarboxylate (BTC), 1,10-phenanthroline (phen), and the transition-metal salt(s) by self-assembly. Single-crystal X-ray structural analysis showed that the resulting 3D microporous supramolecular frameworks consist of a two-dimensional (2D) hydrogen-bonded host framework of [MII(H2O)6(BTC)2]4- (M=Co for 1, Cu for 2, Mn for 3, 4) with rectangular-shaped cavities containing [MII(phen)2(H2O)2]2+ (M=Co for 1-3, Zn for 4) guests. The guest complex is encapsulated in the 2D hydrogen-bonded host framework by hydrogen bonding and aromatic pi-pi stacking interactions, forming the 3D hydrogen-bonded framework. The catalytic activities of 1, 2, 3, and 4 were studied using hydroxylation of phenols with 30% aqueous H2O2 as a test reaction. The compounds displayed a good phenol conversion ratio and excellent channel selectivity in the hydroxylation reaction, with a maximum hydroquinone (HQ)/catechol (CAT) ratio of 3.9. PMID:18439004

  4. Nevadaite, (Cu2+, Al, V3+)6 [Al8 (PO4)8 F8] (OH 2 (H2O)22, a new phosphate mineral species from the Gold Quarry mine, Carlin, Eureka County, Nevada: description and crystal structure

    USGS Publications Warehouse

    Cooper, M.A.; Hawthorne, F.C.; Roberts, Andrew C.; Foord, E.E.; Erd, Richard C.; Evans, H.T., Jr.; Jensen, M.C.

    2004-01-01

    Nevadaite, (Cu2+, ???, Al, V3+)6 (PO4)8 F8 (OH)2 (H2O)22, is a new supergene mineral species from the Gold Quarry mine, near Carlin, Eureka County, Nevada, U.S.A. Nevadaite forms radiating clusters to 1 mm of prismatic crystals, locally covering surfaces more that 2 cm across; individual crystals are elongate on [001] with a length:width ratio of > 10:1 and a maximum diameter of ???30 ??m. It also occurs as spherules and druses associated with colorless to purple-black fluellite, colorless wavellite, strengitevariscite, acicular maroon-to-red hewettite, and rare anatase, kazakhstanite, tinticite, leucophosphite, torbernite and tyuyamunite. Nevadaite is pale green to turquoise blue with a pale powder-blue streak and a vitreous luster; it does not fluoresce under ultra-violet light. It has no cleavage, a Mohs hardness of ???3, is brittle with a conchoidal fracture, and has measured and calculated densities of 2.54 and 2.55 g/cm3, respectively. Nevadaite is biaxial negative, with ?? 1.540, ?? 1.548, ?? 1.553, 2V(obs.) = 76??, 2V(calc.) = 76??, pleochroic with X pale greenish blue, Y very pale greenish blue, Z blue, and with absorption Z ??? X > Y and orientation X = c, Y = a, Z = b. Nevadaite is orthorhombic, space group P21mn, a 12.123(2), b 18.999(2), c 4.961(1) A?? , V 1142.8(2) A??3, Z = 1, a:b:c = 0.6391:1:0.2611. The strongest seven lines in the X-ray powder-diffraction pattern [d in A??(I)(hkl)] are: 6.077(10)(200), 5.618(9)(130), 9.535(8)(020), 2.983(6)(241), 3.430(4)(041), 2.661(4)(061 , and 1.844(4)(352). A chemical analysis with an electron microprobe gave P2O5 32.54, Al2O3 27.07, V2O3 4.24, Fe2O3 0.07, CuO 9.24, ZnO 0.11, F 9.22, H2O (calc.) 23.48, OH ??? F -3.88, sum 102.09 wt.%; the valence states of V and Fe, and the amount of H2O, were determined by crystal-structure analysis. The resulting empirical formula on the basis of 63.65 anions (including 21.65 H2O pfu) is (CU2+2.00 Zn0.02 V3+0.98 Fe3+0.01 Al1.15)??4.16 Al8 P7.90 O32 [F8.37 (OH 1.63]??10 (H2O

  5. Hydrogen bond strength in some beryllium salts, BeXO 4·4H 2O and Me 2Be(XO 4) 2·2H 2O (X = S, Se; Me = K, Rb): Correlation of structural data and infrared spectra

    NASA Astrophysics Data System (ADS)

    Georgiev, M.; Wildner, M.; Stoilova, D.

    2009-08-01

    Infrared spectra of the title compounds are presented and discussed in the regions of the uncoupled O-D stretches of matrix-isolated HDO molecules (isotopically dilute samples). The strengths of the hydrogen bonds are analyzed in terms of the respective O w⋯O bond distances, the Be-OH 2 interactions (synergetic effect), the proton acceptor capabilities of the sulfate and selenate oxygen atoms as deduced from Brown's bond valence sums of the oxygen atoms, the anti-cooperative effect (proton acceptor and proton donor competitive effect). The infrared spectroscopic experiments reveal that comparatively strong hydrogen bonds are formed in the compounds under study, analogical to other hydrated beryllium salts owing to the large ionic potential of the small Be 2+ ions. The wavenumbers of νOD show that the water molecules in BeSO 4·4H 2O and in the double salts are strongly energetically distorted, i.e. their local symmetries deviate remarkably from the C2 v molecular symmetry (for example, Δ ν have values of 74 and 36 cm -1 for H 2O(1) and H 2O(2) in K 2Be(SO 4) 2·2H 2O, and 119 cm -1 in BeSO 4·4H 2O). The hydrogen bonds in K 2Be(SeO 4) 2·2H 2O are stronger than those in K 2Be(SO 4) 2·2H 2O due to the stronger proton acceptor capability of the SeO 42- ions. The proton donor strengths of the water molecules in K 2Be(SO 4) 2·2H 2O and K 2Be(SeO 4) 2·2H 2O are greater than those of the water molecules in BeSO 4·4H 2O and BeSeO 4·4H 2O (i.e. larger deviations from Mikenda's curve) due to the different compositions of the respective beryllium tetrahedra-Be(XO 4) 2(H 2O) 2 in the double salts and Be(H 2O) 4 in the simple ones (proton donor competitive effect). The intramolecular O-H bond lengths are derived from the νOD vs. rOH correlation curve [H.D. Lutz, C. Jung, J. Mol. Struct. 404 (1997) 63].

  6. Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, a new mineral from nepheline syenite pegmatite in the Sakharjok massif, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Lyalina, L. M.; Zolotarev, A. A.; Selivanova, E. A.; Savchenko, Ye. E.; Krivovichev, S. V.; Mikhailova, Yu. A.; Kadyrova, G. I.; Zozulya, D. R.

    2016-05-01

    Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, is a new mineral found in nepheline syenite pegmatite in the Sakharjok alkaline massif, Western Keivy, Kola Peninsula, Russia. The pegmatite mainly consists of nepheline, albite, alkali pyroxenes, amphiboles, biotite and zeolites. Batievaite-(Y) is a late-pegmatitic or hydrothermal mineral associated with meliphanite, fluorite, calcite, zircon, britholite-group minerals, leucophanite, gadolinite-subgroup minerals, titanite, smectites, pyrochlore-group minerals, zirkelite, cerianite-(Ce), rutile, behoite, ilmenite, apatite-group minerals, mimetite, molybdenite, and nickeline. Batievaite-(Y) is pale-cream coloured with white streak and dull, greasy or pearly luster. Its Mohs hardness is 5-5.5. No cleavage or parting was observed. The measured density is 3.45(5) g/cm3. Batievaite-(Y) is optically biaxial positive, α 1.745(5), β 1.747(5), γ 1.752(5) (λ 589 nm), 2V meas. = 60(5)°, 2V calc. = 65°. Batievaite-(Y) is triclinic, space group P-1, a 9.4024(8), b 5.5623(5), c 7.3784(6) Å, α 89.919(2), β 101.408(2), γ 96.621(2)°, V 375.65(6) Å3 and Z = 1. The eight strongest lines of the X-ray powder diffraction pattern [d(Å)(I)(hkl)] are: 2.991(100)(11-2), 7.238(36)(00-1), 3.061(30)(300), 4.350(23)(0-1-1), 9.145(17)(100), 4.042(16)(11-1), 2.819(16)(3-10), 3.745(13)(2-10). The chemical composition determined by electron probe microanalysis (EPMA) is (wt.%): Nb2O5 2.25, TiO2 8.01, ZrO2 2.72, SiO2 29.96, Al2O3 0.56, Fe2O3 0.43, Y2O3 11.45, La2O3 0.22, Ce2O3 0.33, Nd2O3 0.02, Gd2O3 0.07, Dy2O3 0.47, Er2O3 1.07, Tm2O3 0.25, Yb2O3 2.81, Lu2O3 0.45, CaO 24.98, MnO 1.31, MgO 0.01, Na2O 1.13, K2O 0.02, F 2.88, Cl 0.19, H2O 6.75 (determined on the basis of crystal structure data), O = (F,Cl) -1.25, total 97.09 wt.%. The empirical formula based on the EPMA and single-crystal structure analyses is (Y0.81Ca0.65Mn0.15Zr0.12Yb0.11Er0.04Fe3+ 0.04Ce0.02Dy0.02Lu0.02La0.01Tm0.01)Σ2.00((H2O)0.75Ca0.70□0.55)Σ2.00Ca2.00(□0.61Na0.25( H2O

  7. A thermodynamic analysis of the system LiAlSiO4-NaAlSiO4-Al2O3-SiO2-H2O based on new heat capacity, thermal expansion, and compressibility data for selected phases

    NASA Astrophysics Data System (ADS)

    Fasshauer, Detlef W.; Chatterjee, Niranjan D.; Cemic, Ladislav

    Heat capacity, thermal expansion, and compressibility data have been obtained for a number of selected phases of the system NaAlSiO4-LiAlSiO4-Al2O3-SiO2-H2O. All Cp measurements have been executed by DSC in the temperature range 133-823K. The data for T>=223K have been fitted to the function Cp(T)=a+cT -2+dT -0.5+fT -3, the fit parameters being The thermal expansion data (up to 525°C) have been fitted to the function V0(T)=V0(T) [1+v1 (T-T0)+v2 (T-T0)2], with T0=298.15K. The room-temperature compressibility data (up to 6 GPa) have been smoothed by the Murnaghan equation of state. The resulting parameters are These data, along with other phase property and reaction reversal data from the literature, have been simultaneously processed by the Bayes method to derive an internally consistent thermodynamic dataset (see Tables 6 and 7) for the NaAlSiO4-LiAlSiO4-Al2O3-SiO2-H2O quinary. Phase diagrams generated from this dataset are compatible with cookeite-, ephesite-, and paragonite-bearing assemblages observed in metabauxites and common metasediments. Phase diagrams obtained from the same database are also in agreement with the cookeite-free, petalite-, spodumene-, eucryptite-, and bikitaite-bearing assemblages known to develop in the subsolidus phase of recrystallization of lithium-bearing pegmatites. It is gratifying to note that the cookeite phase relations predicted earlier by Vidal and Goffé (1991) in the context of the system Li2O-Al2O3-SiO2-H2O agree with our results in a general way.

  8. Vibrational investigations of CO2-H2O, CO2-(H2O)2, and (CO2)2-H2O complexes isolated in solid neon.

    PubMed

    Soulard, P; Tremblay, B

    2015-12-14

    The van der Waals complex of H2O with CO2 has attracted considerable theoretical interest as a typical example of a weak binding complex with a dissociation energy less than 3 kcal/mol. Up to now, experimental vibrational data are sparse. We have studied by FTIR the complexes involving CO2 and water molecules in solid neon. Many new absorption bands close to the well known monomers fundamentals give evidence for at least three (CO2)n-(H2O)m complexes, noted n:m. Concentration effects combined with a detailed vibrational analysis allow for the identification of sixteen, twelve, and five transitions for the 1:1, 1:2, and 2:1 complexes, respectively. Careful examination of the far infrared spectral region allows the assignment of several 1:1 and 1:2 intermolecular modes, confirmed by the observation of combinations of intra + intermolecular transitions, and anharmonic coupling constants have been derived. Our results demonstrate the high sensibility of the solid neon isolation to investigate the hydrogen-bonded complexes in contrast with the gas phase experiments for which two quanta transitions cannot be easily observed. PMID:26671379

  9. Vibrational investigations of CO2-H2O, CO2-(H2O)2, and (CO2)2-H2O complexes isolated in solid neon

    NASA Astrophysics Data System (ADS)

    Soulard, P.; Tremblay, B.

    2015-12-01

    The van der Waals complex of H2O with CO2 has attracted considerable theoretical interest as a typical example of a weak binding complex with a dissociation energy less than 3 kcal/mol. Up to now, experimental vibrational data are sparse. We have studied by FTIR the complexes involving CO2 and water molecules in solid neon. Many new absorption bands close to the well known monomers fundamentals give evidence for at least three (CO2)n-(H2O)m complexes, noted n:m. Concentration effects combined with a detailed vibrational analysis allow for the identification of sixteen, twelve, and five transitions for the 1:1, 1:2, and 2:1 complexes, respectively. Careful examination of the far infrared spectral region allows the assignment of several 1:1 and 1:2 intermolecular modes, confirmed by the observation of combinations of intra + intermolecular transitions, and anharmonic coupling constants have been derived. Our results demonstrate the high sensibility of the solid neon isolation to investigate the hydrogen-bonded complexes in contrast with the gas phase experiments for which two quanta transitions cannot be easily observed.

  10. A novel polynitrile ligand with different coordination modes: Synthesis, structure and magnetic properties of the series [M(tcnoprOH) 2(H 2O) 2] (M = Mn, Co and Cu) (tcnoprOH - = [(NC) 2CC(OCH 2CH 2CH 2OH)C(CN) 2] -)

    NASA Astrophysics Data System (ADS)

    Benmansour, Samia; Setifi, Fatima; Gómez-García, Carlos J.; Triki, Smail; Coronado, Eugenio; Salaün, Jean-Yves

    2008-11-01

    A novel polynitrile ligand (tcnoprOH - = [(NC) 2CC(OCH 2CH 2CH 2OH)C(CN) 2] -) with up to five potentially coordinating groups has been synthesized in a one-pot reaction from a cyclic acetal and malononitrile. The combination of this novel ligand with different transition metal ions has led to the synthesis of two different structural types with the same formula but with different coordination modes in the ligand. Mn(II) and Cu(II) lead to a μ 2- N, O-coordinating mode in the series of compounds formulated as [M( N, O-tcnoprOH) 2(H 2O) 2] (M = Mn II ( 1) and Cu II ( 2)), whereas Co(II) and, most probably Ni(II), lead to a μ 2- N, N'-coordinating mode in [Co( N, N'-tcnoprOH) 2(H 2O) 2] ( 3). Both structural types consist of linear chains of metal ions connected by a double tcnoprOH - bridge. These ligands are connected to the metal ions through one -CN and one -OH group in compounds 1 and 2 ( N, O-coordinating mode) or through two -CN groups in compound 3. Magnetic measurements show that all compounds are paramagnetic with a low zero field splitting for the Mn derivative.

  11. Metal ion interactions with nucleobases in the tetradentate 1,4,7,10-tetraazacyclododecane (cyclen)-ligand system: Crystal structures of [Cu(cyclen)(adeninato)]·ClO 4·2H 2O, [{Cu(cyclen)} 2(hypoxanthinato)]·(ClO 4) 3, [Cu(cyclen)(theophyllinato)] 3·(ClO 4) 3·2H 2O, and [Cu(cyclen)(xanthinato)]·(0.7ClO 4)·(0.3ClO 4)·3H 2O·(0.5H 2O) 3

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Shahidur; Yuan, Hou Qun; Kikuchi, Takanori; Fujisawa, Ikuhide; Aoki, Katsuyuki

    2010-03-01

    Reaction of 1,4,7,10-tetraazacyclododecane (cyclen) and Cu(ClO 4) 2·6H 2O with nucleobases (adenine, hypoxanthine, xanthine, theophylline, cytosine, or uracil) under alkaline conditions gave four ternary cyclen-metal-nucleobase complexes, [Cu(cyclen)(adeninato)]·ClO 4·2H 2O ( 1), [{Cu(cyclen)} 2(hypoxanthinato)]·(ClO 4) 3 ( 2), [Cu(cyclen)(theophyllinato)] 3·(ClO 4) 3·2H 2O ( 3), and [Cu(cyclen)(xanthinato)]·(0.7ClO 4)·(0.3ClO 4)·3H 2O·(0.5H 2O) 3 ( 4), whose crystal structures were determined by X-ray diffraction. In the adenine complex 1, a cyclen-capped square-pyramidal Cu 2+ ion binds to an adeninato ligand through N(9) with the formation of an intramolecular interligand hydrogen bond between the secondary amino nitrogen of cyclen and N(3) of the base. In the hypoxanthine complex 2, two cyclen-capped Cu 2+ ions bind to a hypoxanthinato ligand, one through N(7) with the formation of an intramolecular N(cyclen)-H···O(6) hydrogen bond and the other through N(9) to form an intramolecular N(cyclen)-H···N(3) hydrogen bond. Similarly, in both the theophylline complex 3 and the xanthine complex 4, each cyclen-capped Cu 2+ ion binds to a theophyllinato or xanthinato ligand through N(7) with the formation of an intramolecular N(cyclen)-H···O(6) hydrogen bond. However, unlike in 2, steric constraints between amino group(s) of cyclen and the methyl group at N(3) of theophylline in 3 or the proton attached to N(9) of xanthine in 4 preclude the metal bonding to N(9) in 3 or N(3) in 4. The significance of intramolecular interligand interaction as a factor that affects metal-binding site(s) on nucleobases is emphasized.

  12. STM/STS observation of polyoxoanions on HOPG surfaces: the wheel-shaped [Cu20Cl(OH)24(H2O)12(P8W48O184)]25- and the ball-shaped [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-PW9O34)12]36-.

    PubMed

    Alam, Mohammad S; Dremov, Viacheslav; Müller, Paul; Postnikov, Andrei V; Mal, Sib Sankar; Hussain, Firasat; Kortz, Ulrich

    2006-04-01

    A combination of scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques have been performed on the wheel-shaped [Cu20Cl(OH)24(H2O)12(P8W48O184)]25- and the ball-shaped [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-PW9O34)12]36- deposited on highly oriented pyrolytic graphite surfaces. Small, regular molecule clusters, as well as separated single molecules, were observed. The size of the molecules is in agreement with the data determined by X-ray crystallography. In STS measurements, we found a rather large contrast at the expected location of the Cu metal centers in our molecules, i.e., the location of the individual Cu ions in their organic matrix is directly addressable by STS. PMID:16562942

  13. Synthesis of Open-Framework Iron Phosphates, [C 6N 2H 14][Fe III2F 2(HPO 4) 2(H 2PO 4) 2]·2H 2O and [C 6N 2H 14] 2[Fe III3(OH)F 3(PO 4)(HPO 4) 2] 2·H 2O, with One- and Three-Dimensional Structures

    NASA Astrophysics Data System (ADS)

    Mahesh, S.; Green, Mark A.; Natarajan, Srinivasan

    2002-05-01

    The hydrothermal syntheses and structures of two new open-framework iron phosphates, I, [C6N2H14][FeIII2F2(HPO4)2 (H2PO4)2].2H2O, II, and [C6N2H14]2[FeIII3(OH)F3(PO4) (HPO4)2]2. H2O, are presented. The structures of both I and II consist of FeO4F2 octahedra and PO4 terahedra linked to form one- and three-dimensional structures. Both the compounds possess infinite one-dimensional chains of Fe-O/F-Fe formed by the FeO4F2 octahedra. The di-protonated DABCO cations are located in between the chains in I and within the channels in II. Whilst I possess the tancoite structure with a new chain composition, II has a three-dimensional structure similar to the gallophosphate, ULM-1. Crystal data for I: M=685.84, monoclinic, space group=C2/c (no. 15), a=7.232(2), b=20.520(7), c=13.933(4) Å, β=97.68(3)°, ν=2049.1(1) Å3, Z=4, ρcalc.=2.223 g cm-3, μ(MoKα)=1.841 mm-1, R1=0.06, wR2=0.12, S=1.17 for 163 parameters; II, M=1303.33, monoclinic, space group =C2/c (no. 15), a=18.1836(2), b=10.0126(7), c=20.0589(4) Å, β=106.08(3)°, ν=3509.0(2) Å3, Z=4, ρcalc=2.467 g cm-3, μ(MoKα)=2.830 mm-1, R1=0.034, wR2=0.081, S=1.06 for 284 parameters.

  14. Climatic modification by CO2, H2O, and aerosol

    NASA Technical Reports Server (NTRS)

    Rasool, I.

    1972-01-01

    Research is reported on the effects of increasing the CO2, aerosols, and water content of the atmosphere on the surface temperature and climatology. An atmospheric model is described with the incoming solar radiation for a planetary albedo of 33 percent, surface temperature of 288 K, relative humidity of 75 percent, cloud cover of 48 percent, CO2 of 0.3 parts per thousand, and aerosol density of two million per square centimeter. The results show that if the CO2 increases by a factor of 1000 or more, the total pressure of the atmosphere increases, and the earth may become as hot as Venus. It is also shown that as the amount of dust particles in the atmosphere increases, the solar radiation decreases, and the surface temperature lowers.

  15. Molecular complex morpholine-CO 2-H 2O

    NASA Astrophysics Data System (ADS)

    Jiang, Huiming; Zhang, Shufen; Xu, Yingmei

    2009-02-01

    Morpholine absorbs CO 2 and H 2O in air to form a molecular complex: morpholinium-1-morpholinecarboxylate-H 2O. The structure of the complex was characterized by X-ray single crystal diffraction, 1H NMR and FT-IR. The crystal structure was determined to be triclinic, space group P1¯ with a = 6.494(2) Å, b = 8.098(4) Å, c = 13.533(4) Å, α = 96.99(3)°, β = 102.57(2)°, γ = 104.15(3)°, Z = 2. The complex is stabilized via three hydrogen bonds between the three components, N…O electrostatic attraction and O…O interaction (electron transfer). Due to electron transfer of the carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O sbnd H bond is considerably shorter than that of free water molecules. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.

  16. Antiferromagnetism of UO2⋅2H2O

    USGS Publications Warehouse

    Pankey, T.; Senftle, F.E.; Cuttitta, F.

    1963-01-01

    Magnetic susceptibility measurements have been made on UO2⋅xH2O for x=1.78 to x=2.13, and from 77° to 375°K. As the value of x decreased the susceptibility increased. Both these data and structural arguments imply that the formula of this compound is U(OH)4 rather than the dihydrate form. Based on this concept the data have been corrected for diamagnetism and also small amounts of UO2 and H2O which were present. The molar susceptibility of U4+ in U(OH)4 is nearly an order of magnitude less than in other uranium compounds, and it is suggested that this is probably due to superexchange between adjacent uranium atoms through intervening oxygen atoms.

  17. A Comparative Time Differential Perturbed Angular Correlation Study of the Nuclear Quadrupole Interaction in HfF4·HF·2H2O Using 180mHf and 181Hf(β-)181Ta as Nuclear Probes: Is Ta an Innocent Spy?

    NASA Astrophysics Data System (ADS)

    Butz, Tilman; Das, Satyendra K.; Manzhur, Yurij

    2009-02-01

    We report on a comparative study of the nuclear quadrupole interaction of the nuclear probes 180mHf and 181Hf(β -)181Ta in HfF4・HF・2H2O using time differential perturbed angular correlations (TDPAC) at 300 K. For the first probe, assuming a Lorentzian frequency distribution, we obtained ωQ= 103(4) Mrad/s, an asymmetry parameter η = 0.68(3), a linewidth δ = 7.3(3.9)%, and full anisotropy within experimental accuracy. For the second probe, assuming a Lorentzian frequency distribution, we obtained three fractions: (1) with 56.5(7)%, ωQ= 126.64(4) Mrad/s and η = 0.9241(4) with a rather small distribution δ = 0.40(8)% which is attributed to HfF4・HF・2H2O; (2) with 4.6(4)%, ωQ = 161.7(3) Mrad/s and η = 0.761(4) assuming no line broadening which is tentatively attributed to a small admixture of Hf2OF6・H2O; (3) the remainder of 39.0(7)% accounts for a rapid loss of anisotropy and is modelled by a perturbation function with a sharp frequency multiplied by an exponential factor exp(-λ t) with λ = 0.55(2) ns-1. Whereas the small admixture of Hf2OF6・H2O escapes detection by the 180mHf probe, there is no rapid loss of roughly half the anisotropy as is the case with 181Hf(β -)181Ta. This loss could in principle be due to fluctuating electric field gradients originating from movements of nearest neighbour HF adducts and/or H2O molecules after nuclear transmutation to the foreign atom Ta which are absent for the isomeric probe. Alternatively, paramagnetic Ta ions could lead to fluctuating magnetic dipole fields which, when combined with fluctuating electric field gradients, could also lead to a rapid loss of anisotropy. In any case, Ta is not an "innocent spy" in this compound. Although 180mHf is not a convenient probe for conventional spectrometers, the use of fast digitizers and software coincidences would allow to use all γ -quanta in the stretched cascade which would greatly improve the efficiency of the spectrometer. 180mHf could also serve as a Pu

  18. Experimental determination of quartz solubility and melting in the system SiO2-H2O-NaCl at 15-20 kbar and 900-1100 °C: implications for silica polymerization and the formation of supercritical fluids

    NASA Astrophysics Data System (ADS)

    Cruz, Miguel F.; Manning, Craig E.

    2015-10-01

    We investigated quartz solubility and melting in the system SiO2-NaCl-H2O at 15-20 kbar and 900-1100 °C using hydrothermal piston-cylinder methods. The solubility of natural, high-purity quartz was determined by weight loss. Quartz solubility decreases with increasing NaCl mole fraction ( X NaCl) at fixed pressure and temperature. The decline is greatest at low X NaCl. The solubility patterns can be explained by changes in the concentration and identity of silica oligomers. Modeling of results at 1000 °C, 15 kbar, reveals that silica monomers and dimers predominate at low Si concentration (high X NaCl), that higher oligomers assumed to be trimers become detectable at X NaCl = 0.23, and that the trimers contain >50 % of dissolved Si at X NaCl = 0. The modeling further implies a hydration number for the silica monomer of 1.6, significantly lower than is observed in previous studies. Results at 15 kbar and 1100 °C provide evidence of two coexisting fluid phases. Although solubility could not be determined directly in these cases, the presence or absence of phases over a range of bulk compositions permitted mapping of the topology of the phase diagram. At 1100 °C, 15 kbar, addition of only a small amount of NaCl ( X NaCl = 0.05) leads to separation of two fluid phases, one rich in H2O and SiO2, the other rich in NaCl with lower SiO2. Textural identification of two fluids is supported by very low quench pH due to preferential partitioning of Na into the fluid that is rich in SiO2 and H2O, confirmed by electron microprobe analyses. The addition of NaCl causes the upper critical end point on the SiO2-H2O melting curve to migrate to significantly higher pressure. Correspondence between depolymerization and phase separation of SiO2-H2O-NaCl fluids indicates that polymerization plays a fundamental role in producing critical mixing behavior in silicate-fluid systems.

  19. Two mixed-ligand lanthanide-hydrazone complexes: [Pr(NCS)3(pbh)2]·H2O and [Nd(NCS)(NO3)(pbh)2(H2O)]NO3·2.33H2O [pbh is N'-(pyridin-2-ylmethylidene)benzo-hydrazide, C13H11N3O].

    PubMed

    Paschalidis, Damianos G; Harrison, William T A

    2016-02-01

    The gel-mediated syntheses and crystal structures of [N'-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ(2) N',O]tris(thiocyanato-κN)praseodymium(III) mono-hydrate, [Pr(NCS)3(C13H11N3O)2]·H2O, (I), and aqua(nitrato-κ(2) O,O')[N'-(pyri-din-2-ylmethylidene-κN)benzohydrazide-κ(2) N',O](thiocyanato-κN)neo-dym-ium(III) nitrate 2.33-hydrate, [Nd(NCS)(NO3)(C13H11N3O)2(H2O)]NO3·2.33H2O, (II), are reported. The Pr(3+) ion in (I) is coordinated by two N,N,O-tridentate N'-(pyridin-2-ylmethylidene)benzohydrazide (pbh) ligands and three N-bonded thio-cyanate ions to generate an irregular PrN7O2 coordination polyhedron. The Nd(3+) ion in (II) is coordinated by two N,N,O-tridentate pbh ligands, an N-bonded thio-cyanate ion, a bidentate nitrate ion and a water mol-ecule to generate a distorted NdN5O5 bicapped square anti-prism. The crystal structures of (I) and (II) feature numerous hydrogen bonds, which lead to the formation of three-dimensional networks in each case. PMID:26958385

  20. Quantitative Measurements of HO2 and other products of n-butane oxidation (H2O2, H2O, CH2O, and C2H4) at elevated temperatures by direct coupling of a jet-stirred reactor with sampling nozzle and cavity ring-down spectroscopy (cw-CRDS).

    PubMed

    Djehiche, Mokhtar; Le Tan, Ngoc Linh; Jain, Chaithanya D; Dayma, Guillaume; Dagaut, Philippe; Chauveau, Christian; Pillier, Laure; Tomas, Alexandre

    2014-11-26

    For the first time quantitative measurements of the hydroperoxyl radical (HO2) in a jet-stirred reactor were performed thanks to a new experimental setup involving fast sampling and near-infrared cavity ring-down spectroscopy at low pressure. The experiments were performed at atmospheric pressure and over a range of temperatures (550-900 K) with n-butane, the simplest hydrocarbon fuel exhibiting cool flame oxidation chemistry which represents a key process for the auto-ignition in internal combustion engines. The same technique was also used to measure H2O2, H2O, CH2O, and C2H4 under the same conditions. This new setup brings new scientific horizons for characterizing complex reactive systems at elevated temperatures. Measuring HO2 formation from hydrocarbon oxidation is extremely important in determining the propensity of a fuel to follow chain-termination pathways from R + O2 compared to chain branching (leading to OH), helping to constrain and better validate detailed chemical kinetics models. PMID:25381864

  1. 13C NMR study of the generation of C2- and C3-deuterated lactic acid by tumoral pancreatic islet cells exposed to D-[1-13C]-, D-[2-13C]- and D-[6-13C]-glucose in 2H2O.

    PubMed

    Willem, R; Biesemans, M; Kayser, F; Malaisse, W J

    1994-03-01

    Tumoral pancreatic islet cells of the RIN5mF line were incubated for 120 min in media prepared in 2H2O and containing D-[1-13C]glucose, D-[2-13C]glucose, and D-[6-13C]glucose. The generation of C2- and C3-deuterated lactic acid was assessed by 13C NMR. The interpretation of experimental results suggests that a) the efficiency of deuteration on the C1 of D-fructose 6-phosphate does not exceed about 47% and 4% in the phosphoglucoisomerase and phosphomannoisomerase reactions, respectively; b) approximately 38% of the molecules of D-glyceraldehyde 3-phosphate generated from D-glucose escape deuteration in the sequence of reactions catalyzed by triose phosphate isomerase and aldolase; and c) about 41% of the molecules of pyruvate generated by glycolysis are immediately converted to lactate, the remaining 59% of pyruvate molecules undergoing first a single or double back-and-forth interconversion with L-alanine. It is proposed that this methodological approach, based on high resolution 13C NMR spectroscopy, may provide novel information on the regulation of back-and-forth interconversion of glycolytic intermediates in intact cells as modulated, for instance, by enzyme-to-enzyme tunneling. PMID:8057796

  2. Two mixed-ligand lanthanide–hydrazone complexes: [Pr(NCS)3(pbh)2]·H2O and [Nd(NCS)(NO3)(pbh)2(H2O)]NO3·2.33H2O [pbh is N′-(pyridin-2-ylmethylidene)benzo­hydrazide, C13H11N3O

    PubMed Central

    Paschalidis, Damianos G.; Harrison, William T. A.

    2016-01-01

    The gel-mediated syntheses and crystal structures of [N′-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ2 N′,O]tris(thiocyanato-κN)praseodymium(III) mono­hydrate, [Pr(NCS)3(C13H11N3O)2]·H2O, (I), and aqua(nitrato-κ2 O,O′)[N′-(pyri­din-2-ylmethylidene-κN)benzohydrazide-κ2 N′,O](thiocyanato-κN)neo­dym­ium(III) nitrate 2.33-hydrate, [Nd(NCS)(NO3)(C13H11N3O)2(H2O)]NO3·2.33H2O, (II), are reported. The Pr3+ ion in (I) is coordinated by two N,N,O-tridentate N′-(pyridin-2-ylmethylidene)benzohydrazide (pbh) ligands and three N-bonded thio­cyanate ions to generate an irregular PrN7O2 coordination polyhedron. The Nd3+ ion in (II) is coordinated by two N,N,O-tridentate pbh ligands, an N-bonded thio­cyanate ion, a bidentate nitrate ion and a water mol­ecule to generate a distorted NdN5O5 bicapped square anti­prism. The crystal structures of (I) and (II) feature numerous hydrogen bonds, which lead to the formation of three-dimensional networks in each case. PMID:26958385

  3. Diffuse reflection infrared Fourier transform (DRIFT) spectra and high-temperature DRIFT spectra of beta-Ni(IO3)2.4H2O, Ni(IO3)2.2H2O, Mg(OH)2, and Zn(OH)F: novel embedding materials.

    PubMed

    Pracht, G; Weckler, B; Lutz, H D

    2003-10-01

    Diffuse reflection infrared Fourier transform (DRIFT) spectra of the hydroxides Mg(OH)2 and Zn(OH)F and the iodate hydrates beta-Ni(IO3)2.4H2O and Ni(IO3)2.2H2O have been recorded at ambient and high temperature. Spectra without shifts of the band maxima compared to those of conventional infrared transmission spectra and without inversion of the bands were obtained by dilution of the compounds to about 2-10% with an appropriate embedding material. alpha-Al2O3, TiO2, ZrO2, PbF2, MgO, BaO, ZnO, Na2SiO3, SiO2 (aerosil), and powdered copper, aluminum, and magnesium were tested as diluents for hydrates and hydroxides, especially at elevated temperatures, as alternatives for the commonly used KBr. Thus, alpha-Al2O3, PbF2, and powdered copper were established as the most favorable diluents. Using these novel embedding materials, high-temperature DRIFT spectra are obtainable at temperatures not accessible with KBr discs. Dehydration and decomposition of the iodate hydrates under study were shown by change or disappearance of the respective water bands. PMID:14639754

  4. The role of steric constraints in the formation of rare aqua bridged coordination polymers: Synthesis, characterization and X-ray structures of polymeric, [Cu(2-chlorobenzoate)2(β-picoline)2(μ-H2O)]n and monomeric, [Cu(2-chlorobenzoate)2(γ-picoline)2(H2O)

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Sharma, Raj Pal; Venugopalan, Paloth; Aree, Thammarat; Ferretti, Valeria

    2015-07-01

    Reaction of hydrated copper(II) 2-chloro-benzoate with β-/γ-picoline in methanol: water mixture (4:1 v/v) yielded polymeric [Cu(2-chlorobenzoate)2(β-picoline)2(μ-H2O)]n; 1 and monomeric [Cu(2-chlorobenzoate)2(γ-picoline)2(H2O)]; 2. The newly synthesized complexes have been characterized by elemental analyses, FT-IR spectroscopy, UV-Visible spectroscopy, TGA and single crystal X-ray structure determination. X-ray crystallographic analysis revealed that both complexes crystallize in the monoclinic crystal system with space group and unit cell dimensions: C2/c; a = 51.71 Å, b = 10.58 Å, c = 10.02 Å and β = 100.5° for 1 and P21/c; a = 11.81 Å, b = 16.33 Å, c = 13.79 Å and β = 90.77° for 2. Whereas in 1 the presence of constituent and mediating water molecules running along a-axis gives rise to 1-dimensional zig-zag polymer chains, in complex 2, the presence of square pyramidal arrangement of ligands around copper(II) center results in monomeric structure. Various non-covalent interactions like Osbnd H⋯O, Csbnd H⋯O and Csbnd H⋯л have been observed to play a decisive role in the stabilization of crystal lattices in both complexes.

  5. Hydrogen-bonded pillars of alternating chiral complex cations and anions: 1. Synthesis, characterization, X-ray structure and thermal stability of catena-{[Co(H(2)oxado)(3)][Cr(C(2)O(4))(3)].5H(2)O} and of its precursor (H(3)oxado)[Co(H(2)oxado)(3)](SO(4))(2).2H(2)O.

    PubMed

    Bélombé, M M; Nenwa, J; Mbiangué, Y A; Majoumo-Mbé, F; Lönnecke, P; Hey-Hawkins, E

    2009-06-21

    Compound (H(3)oxado)[Co(H(2)oxado)(3)](SO(4))(2).2H(2)O () (H(3)oxado(+) = oxamide dioximemonoximium) reacted metathetically with Ba(6)(H(2)O)(17)[Cr(C(2)O(4))(3)](4).7H(2)O in water to give the one-dimensional complex salt {[Co(H(2)oxado)(3)][Cr(C(2)O(4))(3)].5H(2)O}(infinity) () (H(2)oxado = oxamide dioxime). Compounds and were characterized by elemental analysis, FTIR, UV-Vis and by single crystal X-ray structure determination. The structure of consists of infinite pillars of alternating chiral complex cations and anions linked together along [100] by electrostatic and longitudinal O-HO interactions, with an average intrachain CoCr separation of 4.94 A. Equatorial N-HO bridges cross-link neighboring pillars (which are of opposite chirality) and consolidate a three-dimensional lattice framework which delineates elliptic nanochannels parallel to the a axis, encapsulating highly disordered water molecules. The thermal stability of both compounds was assessed by TGA, and the effective magnetic moment of , checked at room temperature, revealed considerable spin-orbit coupling. PMID:19488450

  6. A kinetic study of the reactions of Fe+ with N2O, N2, O2, CO2 and H2O, and the ligand-switching reactions Fe+.X + Y --> Fe+.Y + X (X = N2, O2, CO2; Y = O2, H2O).

    PubMed

    Vondrak, T; Woodcock, K R I; Plane, J M C

    2006-01-28

    A series of reactions involving Fe(+) ions were studied by the pulsed laser ablation of an iron target, with detection of ions by quadrupole mass spectrometry at the downstream end of a fast flow tube. The reactions of Fe(+) with N(2)O, N(2) and O(2) were studied in order to benchmark this new technique. Extending measurements of the rate coefficient for Fe(+) + N(2)O from 773 K to 185 K shows that the reaction exhibits marked non-Arrhenius behaviour, which appears to be explained by excitation of the N(2)O bending vibrational modes. The recombination of Fe(+) with CO(2) and H(2)O in He was then studied over a range of pressure and temperature. The data were fitted by RRKM theory combined with ab initio quantum calculations on Fe(+).CO(2) and Fe(+).H(2)O, yielding the following results (120-400 K and 0-10(3) Torr). For Fe(+) + CO(2): k(rec,0) = 1.0 x 10(-29) (T/300 K)(-2.31) cm(6) molecule(-2) s(-1); k(rec,infinity) = 8.1 x 10(-10) cm(3) molecule(-1) s(-1). For Fe(+) + H(2)O: k(rec,0) = 5.3 x 10(-29) (T/300 K)(-2.02) cm(6) molecule(-2) s(-1); k(rec,infinity) = 2.1 x 10(-9) (T/300 K)(-0.41) cm(3) molecule(-1) s(-1). The uncertainty in these rate coefficients is determined using a Monte Carlo procedure. A series of exothermic ligand-switching reactions were also studied at 294 K: k(Fe(+).N(2) + O(2)) = (3.17 +/- 0.41) x 10(-10), k(Fe(+).CO(2) + O(2)) = (2.16 +/- 0.35) x 10(-10), k(Fe(+).N(2) + H(2)O) = (1.25 +/- 0.14) x 10(-9) and k(Fe(+).O(2) + H(2)O) = (8.79 +/- 1.30) x 10(-10) cm(3) molecule(-1) s(-1), which are all between 36 and 52% of their theoretical upper limits calculated from long-range capture theory. Finally, the role of these reactions in the chemistry of meteor-ablated iron in the upper atmosphere is discussed. The removal rates of Fe(+) by N(2), O(2), CO(2) and H(2)O at 90 km altitude are approximately 0.1, 0.07, 3 x 10(-4) and 1 x 10(-6) s(-1), respectively. The initially formed Fe(+).N(2) and Fe(+).O(2) are converted into the H(2)O complex at

  7. Model of the Second Most Abundant Cisplatin-DNA Cross-Link: X-ray Crystal Structure and Conformational Analysis of cis-[(NH(3))(2)Pt(9-MeA-N7)(9-EtGH-N7)](NO(3)).2H(2)O (9-MeA = 9-Methyladenine; 9-EtGH = 9-Ethylguanine).

    PubMed

    Schröder, Guy; Kozelka, Jirí; Sabat, Michal; Fouchet, Marie-Hélène; Beyerle-Pfnür, Rut; Lippert, Bernhard

    1996-03-13

    A model compound of the second most abundant DNA adduct of the antitumor agent cisplatin has been synthesized and structurally and spectroscopically characterized and its conformational behavior examined: cis-[(NH(3))(2)Pt(9-MeA-N7)(9-EtGH-N7)](NO(3))(2).2H(2)O (9-MeA = 9-methyladenine; 9-EtGH = 9-ethylguanine) crystallizes in the monoclinic system, space group P2(1)/n (No. 14) with a = 7.931(2), b = 11.035(3), c = 26.757(6) Å, beta = 94.94(2) degrees, and Z = 4. The two purine bases adopt a head-to-head orientation, with NH(2) of 9-MeA and CO of 9-EtGH being at the same side of the Pt coordination plane. A theoretical conformational analysis of the complex cis-[(NH(3))(2)Pt(Ade)(Gua)](2+) (Ade = adenine; Gua = guanine) based on molecular mechanics calculations of the nonbonded energy has revealed four minimum-energy zones similar to those derived previously for cis-[(NH(3))(2)Pt(Gua)(2)](2+) (Kozelka; et al. Eur. J. Biochem. 1992, 205, 895). This conformational analysis has allowed, together with the calculation of chemical shifts due to ring effects, the attribution of the two conformers observed for cis-[(NH(3))(2)Pt{d(ApG)}](+) by Dijt et al. (Eur. J. Biochem. 1989, 179, 344) to the two head-to-head conformational zones. The orientation of the two nucleobases in the crystal structure of cis-[(NH(3))(2)Pt(9-MeA)(9-EtGH)](2+) corresponds, according to our analysis, roughly to that preferentially assumed by the minor rotamer of cis-[(NH(3))(2)Pt{d(ApG)}](+). PMID:11666386

  8. Holo- and hemidirected lead(II) in the polymeric [Pb(4)(mu-3,4-TDTA)2(H2O)2]*4H2O complex. N,N,N',N'-tetraacetate ligands derived from o-phenylenediamines as sequestering agents for lead(II).

    PubMed

    Sanchiz, Joaquín; Esparza, Pedro; Villagra, Diego; Domínguez, Sixto; Mederos, Alfredo; Brito, Felipe; Araujo, Lorena; Sánchez, Agustin; Arrieta, Juan Manuel

    2002-11-18

    The coordinating ability of the ligands 3,4-toluenediamine-N,N,N',N'-tetraacetate (3,4-TDTA), o-phenylenediamine-N,N,N',N'-tetraacetate (o-PhDTA), and 4-chloro-1,2-phenylenediamine-N,N,N',N'-tetraacetate (4-Cl-o-PhDTA) (H4L acids) toward lead(II) is studied by potentiometry (25 degrees C, I = 0.5 mol x dm(-3) in NaClO4), UV-vis spectrophotometry, and 207Pb NMR spectrometry. The stability constants of the complex species formed were determined. X-ray diffraction structural analysis of the complex [Pb4(mu-3,4-TDTA)4(H2O)2]*4H2O (1) revealed that 1 has a 2-D structure. The layers are built up by the polymerization of centrosymmetric [Pb4L2(H2O)2] tetranuclear units. The neutral layers have the aromatic rings of the ligands pointing to the periphery, whereas the metallic ions are located in the central part of the layers. In compound 1, two types of six-coordinate lead(II) environments are produced. The Pb(1) is coordinated to two nitrogen atoms and four carboxylate oxygens from the ligand, whereas Pb(2) has an O6 trigonally distorted octahedral surrounding. The lead(II) ion is surrounded by five carboxylate oxygens and a water molecule. The carboxylate oxygens belong to four different ligands that are also joined to four other Pb(1) ions. The selective uptake of lead(II) was analyzed by means of chemical speciation diagrams as well as the so-called conditional or effective formation constants K(Pb)eff. The results indicate that, in competition with other ligands that are strong complexing agents for lead(II), our ligands are better sequestering agents in acidic media. PMID:12425632

  9. Common Building Motifs in Ba2Fe3(PO4)4·2H2O, BaFe3(PO4)3, and Na3Fe3(PO4)4: Labile Fe(2+)/Fe(3+) Ordering and Charge-Dependent Magnetism.

    PubMed

    David, Rénald; Pautrat, Alain; Kabbour, Houria; Mentré, Olivier

    2016-05-01

    Two new mixed-valence Fe(2/3+) barium phosphates have been synthesized in hydrothermal conditions and characterized: Ba2Fe(2.66+)3(PO4)4·2H2O (compound 1, ratio Fe(3+)/Fe(2+) = 2:1, orthorhombic space group Pbca, a = 6.71240(10) Å, b = 10.6077(2) Å, c = 20.9975(5) Å, R1 = 3.39%) and BaFe(2.33+)3(PO4)3 (compound 2, ratio Fe(3+)/Fe(2+) = 1:2, orthorhombic, space group Imma with a = 10.5236(3) Å, b = 13.4454(4) Å, c = 6.6411(2) Å, R1 = 1.63%). 1 has a two-dimensional crystal structure built of [Fe(2.5+)2Fe(3+)1(PO4)4](4-) layers with charge segregation on two individual Fe crystal sites, in contrast to the single valence on these two sites found in similar layers of Na3Fe(3+)3(PO4)4. The crystal structure of 2 is formed of the same layers but condensed into a 3D [Fe(2+)2Fe(3+)1(PO4)3](2-) framework. The complete Fe(2+) vs Fe(3+) charge ordering on the two available sites differs from what was found in the two previous cases and denotes a remarkable charge adaptability of the common elementary units. Compared to the antiferromagnetic Na3Fe(3+)3(PO4)4 the partial iron reduction into Fe(2+) is responsible for strong ferromagnetic components along the c-easy axis for both 1 and 2. Additionally 1 shows multiple magnetization steps in the perpendicular direction, giving raise to atypical anisotropic magnetism into a complex magnetic phase diagram. PMID:27097360

  10. A novel amido-pyrophosphate Mn(II) chelate complex with the synthetic ligand O{P(O)[NHC(CH3)3]2}2 (L): [Mn(L)2{OC(H)N(CH3)2}2]Cl2·2H2O.

    PubMed

    Tarahhomi, Atekeh; Pourayoubi, Mehrdad; Fejfarová, Karla; Dušek, Michal

    2013-03-01

    The title complex, trans-bis(dimethylformamide-κO)bis{N,N'-N'',N'''-tetra-tert-butyl[oxybis(phosphonic diamide-κO)]}manganese(II) dichloride dihydrate, [Mn(C16H40N4O3P2)2(C3H7NO)2]Cl2·2H2O, is the first example of a bis-chelate amido-pyrophosphate (pyrophosphoramide) complex containing an O[P(O)(NH)2]2 fragment. Its asymmetric unit contains half of the complex dication, one chloride anion and one water molecule. The Mn(II) atom, located on an inversion centre, is octahedrally coordinated, with a slight elongation towards the monodentate dimethylformamide ligand. Structural features of the title complex, such as the P=O bond lengths and the planarity of the chelate ring, are compared with those of previously reported complexes with six-membered chelates involving the fragments C(O)NHP(O), (X)NP(O) [X = C(O), C(S), S(O)2 and P(O)] and O[P(O)(N)2]2. This analysis shows that the six-membered chelate rings are less puckered in pyrophosphoramide complexes containing a P(O)OP(O) skeleton, such as the title compound. The extended structure of the title complex involves a linear aggregate mediated by N-H...O and N-H...Cl hydrogen bonds, in which the chloride anion is an acceptor in two additional O-H...Cl hydrogen bonds. PMID:23459342

  11. Crystal and molecular structure of the coordination compounds of Er3+ with 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene [Er L {2/1}(NO3)2]2[Er(NO3)2(H2O)5]0.333(NO3)2.333 · 2.833H2O and its ethyl substituted derivative [Er L {2/2}(NO3)2][Er(NO3)5]0.5 · 0.5H2O

    NASA Astrophysics Data System (ADS)

    Polyakova, I. N.; Baulin, V. E.; Ivanova, I. S.; Pyatova, E. N.; Sergienko, V. S.; Tsivadze, A. Yu.

    2015-01-01

    The coordination compounds of Er3+ with 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene [Er L {2/1}(NO3)2]2[Er(NO3)2(H2O)5]0.333(NO3)2.333 · 2.833H2O ( I) and its ethyl substituted derivative [Er L {2/2}(NO3)2][Er(NO3)5]0.5 · 0.5H2O ( II) are synthesized and their crystal structures are studied. I and II contain [Er L 2(NO3)2]+ complex cations of identical composition and close structure. The eight-vertex polyhedron of the Er atom in the shape of a distorted octahedron with two split trans vertices is formed by the O atoms of the phosphoryl groups of L ligands and nitrate anions. L ligands close nine-membered metallocycles. The structures contain spacious channels which are populated differently, namely, by disordered [Er(NO3)2(H2O)5]+ complex cations, NO{3/-} anions, and crystallization water molecules in I and disordered [Er(NO3)5]2- complex anions and crystallization water molecules in II. The IR spectra of I and II are studied.

  12. Precipitation kinetics of calcite in the system CaCO 3H2OC02: The conversion to CO 2 by the slow process H ++HCO 3- → CO 2+H 2O as a rate limiting step

    NASA Astrophysics Data System (ADS)

    Dreybrodt, W.; Eisenlohr, L.; Madry, B.; Ringer, S.

    1997-09-01

    Precipitation rates of CaCO 3 from supersaturated solutions in the H 2OCO 2CaCO 3 system are controlled by three rate-determining processes: the kinetics of precipitation at the mineral surface, mass transport of the reaction species involved to and from the mineral surface, and the slow kinetics of the overall reaction HCO 3-+H + → CO 2+H 2O. A theoretical model by Buhmann and Dreybrodt (1985a,b) taking these processes into account predicts that, due to the slow kinetics of this reaction, precipitation rates to the surface of CaC0 3 minerals depend critically on the ratio V/A of the volume V of the solution to the surface area A of the mineral in contact with it, for both laminar and turbulent flow. We have performed measurements of precipitation rates in a porous medium of sized particles of marble, limestone, and synthetic calcite, with V/A ratios ranging from 3·10 -4 to 1.2·10 -2 cm at 10°C. Calcite was precipitated from supersaturated solutions with [Ca 2+] ≈ 4 mmol/L and an initial PCO2 of 5·10 -3 or 1·10 -3 atm, respectively, using experimental conditions which prevented exchange of CO 2 with the atmosphere, i.e., closed system. The results are in qualitative agreement with the theoretical predictions. Agreement with the observed data, however, is obtained by modifying the rate law of Plummer et al. (1978) to take into account surface-controlled inhibition effects. Experiments with supersaturated solutions containing carbonic anhydrase, an enzyme which enhances the conversion of HCO 3- into CO 2, yield rates increased by a factor of up to 15. This provides for the first time unambiguous experimental evidence that this reaction is rate limiting. We have also measured precipitation rates in batch experiments, stirring sized mineral particles in a solution with V/A ranging from 0.03 to 0.75 cm. These experiments also give clear evidence on the importance of the conversion of HCO 3- into CO 2 as rate limiting step. Taken together our experiments

  13. Infrared Spectra of the CO_2-H_2O, CO_2-(H_2O)2, and (CO_2)2-H_2O Complexes Isolated in Solid Neon Between 90 and 5300 wn

    NASA Astrophysics Data System (ADS)

    Tremblay, Benoît; Soulard, Pascale

    2015-06-01

    The van der Waals complex of H_2O with CO_2 has attracted considerable theoretical interest since it is a typical example of a weak binding complex (less than 3 kcal/mol), but a very few IR data are available in gas. For these reasons, we have studied in solid neon hydrogen bonded complexes involving carbon dioxide and water molecules. Evidence for the existence of at least three (CO_2)m(H_2O)n, or m:n, complexes has been obtained from the appearance of many new absorptions near the well-know monomers fundamental transitions. Concentration effects and detailed vibrational analysis allowed identification of fifteen, eleven and four transitions for the 1:1, 1:2, and 2:1 complexes, respectively. Careful examination of the far infrared allows the assignment of several 1:1 and 1:2 intermolecular modes, confirmed by the observation of combinations of intra+intermolecular transitions. All of these results significantly increase the number of one and, especially, two quanta vibrational transitions observed for these complexes, and anharmonic coupling constants have been derived. This study shows the high sensibility of the solid neon isolation for the spectroscopy of the hydrogen-bonded complexes since two quanta transitions can't be easily observed in gas phase.

  14. Polynuclear complexes with bridging pyrophosphate ligands: synthesis and characterisation of {[(bipy)Cu(H2O)(mu-P2O7)Na2(H2O)6] x 4H2O}, {[(bipy)Zn-(H2O)(mu-P2O7)Zn(bipy)]2 x 14H2O} and {[(bipy)(VO)2]2(mu-P2O7)] x 5H2O}.

    PubMed

    Doyle, Robert P; Nieuwenhuyzen, Mark; Kruger, Paul E

    2005-12-01

    The reaction in water of M(II) ions (M = Cu, 1; Zn, 2; VO, 3) with 2,2'-bipyridine (bipy) followed by Na4P2O7 leads to the formation of three new complexes which feature the pyrophosphate anion, P2O7(4-), as a bridging ligand. Single crystal X-ray diffraction revealed 1 to be {[(bipy)Cu(H2O)(micro-P2O7)Na2(H2O)6] x 4H2O}, and 2 as a tetranuclear Zn(II) complex, {[(bipy)Zn(H2O)(micro-P2O7)Zn(bipy)]2 x 14H2O}. The structure of 1 consists of a mononuclear [(bipy)Cu(H2O)(P2O7)]2- unit that links via a pyrophosphate bridge to two Na atoms. The hydrated six-coordinate Na atoms themselves join together through bridging water molecules to generate a 2D Na-water sheet. The structure of 2 consists of a tetranuclear Zn(II) cluster (dimer-of-dimers) with two pyrophosphate ligands bridging between four metal centres. Adjacent clusters interact through face-to-face pi-pi interactions via the bipy ligands to yield a 2D sheet. Adjacent sheets pack in register to create channels, which are filled by the water molecules of crystallisation. An intricate 2D H-bonded water network separates adjacent sheets and encapsulates the tetranuclear clusters. Aspects of the pyrophosphate coordination modes in 1 and 2 are of structural relevance to those found within the inorganic pyrophosphatases. Compound 3, {[(bipy)(VO)2]2(micro-P2O7)] x 5H2O}, was isolated as an insoluble lime-green powder. Its dinuclear structure was elucidated from elemental and thermal analysis, magnetic susceptibility measurement and IR spectroscopy. The latter displayed characteristic bridging pyrophosphate and signature V=O stretches, which were corroborated by contrast to the IR spectra of 1 and 2 and through comparison with those found in the structurally characterised dinuclear complex, {[(bipy)Cu(H2O)]2(micro-P2O7) x 7H2O}, 4. PMID:16471055

  15. Surface and Electrochemical Behavior of HSLA in Supercritical CO2-H2O Environment

    SciTech Connect

    M. Ziomek-Moroz; G. R. Holcomb; J. Tylczak; J. Beck; M. Fedkin; S. Lvov

    2012-01-11

    General corrosion was observed on high strength low alloy carbon steel after electrochemical impedance spectroscopy experiments (EIS) performed in H{sub 2}O saturated with CO{sub 2} at 50 C and 15.2 MPa. However, general and localized were observed on the same material surfaces after the EIS experiments performed in supercritical CO{sub 2} containing approximately 6100 ppmv H{sub 2}O at 50 C and 15.2 MPa. The general corrosion areas were uniformly covered by the FeCO{sub 3}-like phase identified by X-ray diffraction (XRD). In the area of localized corrosion, XRD also revealed FeCO{sub 3}-rich islands embedded in {alpha}-iron. The energy dispersive X-ray (EDX) analysis revealed high concentrations of iron, carbon, and oxygen in the area affected by general corrosion and in the islands formed in the area of localized corrosion. The real and imaginary impedances were lower in H{sub 2}O saturated with CO{sub 2} than those in the supercritical CO{sub 2} containing the aqueous phase indicating faster corrosion kinetics in the former.

  16. Mineralization of basalts in the CO2-H2O-SO2-O2 system.

    PubMed

    Schaef, Herbert T; Horner, Jake A; Owen, Antoinette T; Thompson, Chris J; Loring, John S; McGrail, Bernard P

    2014-05-01

    Sequestering carbon dioxide (CO2) containing minor amounts of co-contaminants in geologic formations was investigated in the laboratory through the use of high pressure static experiments. Five different basalt samples were immersed in water equilibrated with supercritical CO2 containing 1 wt % sulfur dioxide (SO2) and 1 wt % oxygen (O2) at reservoir conditions (∼ 100 bar, 90 °C) for 48 and 98 days. Gypsum (CaSO4) was a common precipitate, occurred early as elongated blades with striations, and served as substrates for other mineral products. In addition to gypsum, bimodal pulses of water released during dehydroxylation were key indicators, along with X-ray diffraction, for verifying the presence of jarosite-alunite group minerals. Well-developed pseudocubic jarosite crystals formed surface coatings, and in some instances, mixtures of natrojarosite and natroalunite aggregated into spherically shaped structures measuring 100 μm in diameter. Reaction products were also characterized using infrared spectroscopy, which indicated OH and Fe-O stretching modes. The presences of jarosite-alunite group minerals were found in the lower wavenumber region from 700 to 400 cm(-1). A strong preferential incorporation of Fe(III) into natrojarosite was attributed to the oxidation potential of O2. Evidence of CO2 was detected during thermal decomposition of precipitates, suggesting the onset of mineral carbonation. PMID:24669947

  17. Kinetics of the reaction OH + H2O2 yields HO2 + H2O

    NASA Technical Reports Server (NTRS)

    Sridharan, U. C.; Reimann, B.; Kaufman, F.

    1980-01-01

    The paper describes an experimental study of the title reaction that uses the discharge-flow technique, laser-induced-fluorescence detection of OH and simultaneous monitoring of O and H atoms in the 250-459 K range. The reaction is normal and free from surface effect interference in Teflon or halocarbon wax-coated tube, but not in clean Pyrex. OH radicals are generated in three ways and at low concentrations to eliminate side reactions. The rate constants were determined at 298 K and over the 250-459 K range, with a factor of two higher at 298 K and factors of 3 to 5 higher at 10 to 30 km altitude in the terrestrial atmosphere than previous studies have indicated. The effect of the higher rate constant on atmospheric processes and on recent laboratory measurements of other reactions is also discussed.

  18. 2H 2O quadrupolar splitting used to measure water exchange in erythrocytes

    NASA Astrophysics Data System (ADS)

    Kuchel, Philip W.; Naumann, Christoph

    2008-05-01

    The 2H NMR resonance from HDO (D = 2H) in human red blood cells (RBCs) suspended in gelatin that was held stretched in a special apparatus was distinct from the two signals that were symmetrically arranged on either side of it, which were assigned to extracellular HDO. The large extracellular splitting is due to the interaction of the electric quadrupole moment of the 2H nuclei with the electric field gradient tensor of the stretched, partially aligned gelatin. Lack of resolved splitting of the intracellular resonance indicated greatly diminished or absent ordering of the HDO inside RBCs. The separate resonances enabled the application of a saturation transfer method to estimate the rate constants of transmembrane exchange of water in RBCs. However both the theory and the practical applications needed modifications because even in the absence of RBCs the HDO resonances were maximally suppressed when the saturating radio-frequency radiation was applied exactly at the central frequency between the two resonances of the quadrupolar HDO doublet. More statistically robust estimates of the exchange rate constants were obtained by applying two-dimensional exchange spectroscopy (2D EXSY), with back-transformation analysis. A monotonic dependence of the estimates of the efflux rate constants on the mixing time, tmix, used in the 2D EXSY experiment were seen. Extrapolation to tmix = 0, gave an estimate of the efflux rate constant at 15 °C of 31.5 ± 2.2 s -1 while at 25 °C it was ˜50 s -1. These values are close to, but less than, those estimated by an NMR relaxation-enhancement method that uses Mn 2+ doping of the extracellular medium. The basis for this difference is thought to include the high viscosity of the extracellular gel. At the abstract level of quantum mechanics we have used the quadrupolar Hamiltonian to provide chemical shift separation between signals from spin populations across cell membranes; this is the first time, to our knowledge, that this has been achieved.

  19. The HO2 + (H2O)n + O3 reaction: an overview and recent developments*

    NASA Astrophysics Data System (ADS)

    Viegas, Luís P.; Varandas, António J. C.

    2016-03-01

    The present work is concerned with the reaction of the hydroperoxyl radical with ozone, which is key in the atmosphere. We first give a brief overview which emphasizes theoretical work developed at the authors' Group, considering not only the naked reaction (n = 0) but also the reaction with one water molecule added to the reactants (n = 1). Aiming at a broad and contextual understanding of the role of water, we have also very recently published the results of the investigation considering the addition of water dimers (n = 2) and trimers (n = 3) to the reactants. Such results are also succinctly addressed before we present our latest and unpublished research endeavors. These consist of two items: the first one addresses a new mechanistic pathway for hydrogen-abstraction in n = 2-4 cases, in which we observe a Grotthuss-like hydrogen shuttling mechanism that interconverts covalent and hydrogen bonds (water molecules are no longer spectators); the second addresses our exploratory calculations of the HO2 + O3 reaction inside a (H2O)20 water cage, where we strive to give a detailed insight of the molecular processes behind the uptake of gas-phase molecules by a water droplet. Supplementary material in the form of one zip file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2016-60733-5Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.

  20. Materials Data on Si2H2O3 (SG:148) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. The Martian climate and energy balance models with CO2/H2O atmospheres

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.

    1986-01-01

    The analysis begins with a seasonal energy balance model (EBM) for Mars. This is used to compute surface temperature versus x = sin(latitude) and time over the seasonal cycle. The core model also computes the evolving boundaries of the CO2 icecaps, net sublimational/condensation rates, and the resulting seasonal pressure wave. Model results are compared with surface temperature and pressure history data at Viking lander sites, indicating fairly good agreement when meridional heat transport is represented by a thermal diffusion coefficient D approx. 0.015 W/sq. m/K. Condensational wind distributions are also computed. An analytic model of Martian wind circulation is then proposed, as an extension of the EMB, which incorporates vertical wind profiles containing an x-dependent function evaluated by substitution in the equation defining the diffusion coefficient. This leads to a parameterization of D(x) and of the meridional circulation which recovers the high surface winds predicted by dynamic Mars atmosphere models (approx. 10 m/sec). Peak diffusion coefficients, D approx. 0.6 w/sq m/K, are found over strong Hadley zones - some 40 times larger than those of high-latitude baroclinic eddies. When the wind parameterization is used to find streamline patterns over Martian seasons, the resulting picture shows overturning hemispheric Hadley cells crossing the equator during solstices, and attaining peak intensities during the south summer dust storm season, while condensational winds are most important near the polar caps.

  2. Surface Studies of HSLA Steel after Electrochemical Corrosion in Supercritical CO2-H2O Environment

    SciTech Connect

    Ziomek-Moroz, M. Holcomb, G. Tylczak, J Beck, J Fedkin, M. Lvov, S.

    2011-10-01

    In aqueous phase saturated with CO2, X-65 sample underwent general corrosion with formation of FeCO3. In supercritical CO2 containing water phase, two major regions are present on the sample surface after the EIS experiment. One region covered with corrosion products identified as FeCO3 and the other containing Fe, oxygen, and carbon-rich islands embedded in metal matrix identified as {alpha}-Fe. Precipitation of FeCO3 from Fe2+ and CO3 2- is responsible for formation of passive layer in oxygen-deficient, CO2 rich aqueous environment. Mechanisms of corrosion degradation occurring in supercritical CO2 as a function. Transport of supercritical CO{sub 2} is a critical element for carbon capture from fossil fuel power plants and underground sequestration. Although acceptable levels of water in supercritical CO{sub 2} (up to {approx} 5 x 10{sup -4}g/dm{sup 3}) have been established, their effects on the corrosion resistance of pipeline steels are not fully known. Moreover, the presence of SO{sub 2}, O{sub 2} impurities in addition to the water can make the fluid more corrosive and, therefore, more detrimental to service materials. Also, in this case, limited data are available on materials performance of carbon steels. to advance this knowledge, other service alloys are being investigated in the high pressure high temperature cell containing impure CO{sub 2} fluids using reliable non-destructive in-situ electrochemical methods. The electrochemical results are being augmented by a number of surface analyses of the corroded surfaces.

  3. Effect of the greenhouse gases (CO2, H2O, SO2) on Martian paleoclimate

    NASA Technical Reports Server (NTRS)

    Postawko, S. E.; Kuhn, W. R.

    1986-01-01

    There is general agreement that certain surface features on Mars are indicative of the presence of liquid water at various times in the geologic past. In particular, the valley networks are difficult to explain by a mechanism other than the flow of liquid water. It has been suggested in several studies that a thick CO2 atmosphere on Mars early in its history could have provided a greenhouse warming that would have allowed the flow of water either on the surface or just below the surface. However, this effect was examined with a detailed radiation model, and it was found that if reduced solar luminosity early in the history of the solar system is taken into account, even three bars of CO2 will not provide sufficient greeenhouse warming. The addition of water vapor and sulflur dioxide (both plausible gases that may have been emitted by Martian volcanoes) to the atmosphere also fail to warm the surface above 273 K for reduced solar luminosity conditions. The increase in temperature may be large enough, however, for the formation of these features by brines.

  4. The Martian climate: Energy balance models with CO2/H2O atmospheres

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.

    1984-01-01

    Progress in the development of a multi-reservoir, time dependent energy balance climate model for Mars driven by prescribed insolation at the top of the atmosphere is reported. The first approximately half-year of the program was devoted to assembling and testing components of the full model. Specific accomplishments were made on a longwave radiation code, coupling seasonal solar input to a ground temperature simulation, and conceptualizing an approach to modeling the seasonal pressure waves that develop in the Martian atmosphere as a result of sublimation and condensation of CO2 in polar regions.

  5. The Martian climate: Energy balance models with CO2/H2O atmospheres

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.

    1985-01-01

    Coupled equations are developed for mass and heat transport in a seasonal Mars model with condensation and sublimation of CO2 at the polar caps. Topics covered include physical considerations of planetary as mass and energy balance; effects of phase changes at the surface on mass and heat flux; atmospheric transport and governing equations; and numerical analysis.

  6. Materials Data on NiP2H2O7 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Ice Grain Collisions in Comparison: CO2, H2O, and Their Mixtures

    NASA Astrophysics Data System (ADS)

    Musiolik, Grzegorz; Teiser, Jens; Jankowski, Tim; Wurm, Gerhard

    2016-08-01

    Collisions of ice particles play an important role in the formation of planetesimals and comets. In recent work, we showed that CO2 ice behaves like silicates in collisions. The resulting assumption was that it should therefore stick less efficiently than H2O ice. Within this paper, a quantification of the latter is presented. We used the same experimental setup to study collisions of pure CO2 ice, pure water ice, and 50% mixtures by mass between CO2 and water at 80 K, 1 mbar, and an average particle size of ˜90 μm. The results show a strong increase of the threshold velocity between sticking and bouncing with increasing water content. This supports the idea that water ice is favorable for early growth phases of planets in a zone within the H2O and the CO2 iceline.

  8. CaCl2-H2O in the supercritical and two-phase ranges

    NASA Astrophysics Data System (ADS)

    Oakes, C. S.; Bodnar, R. J.; Simonson, J. M.; Pitzer, K. S.

    1995-03-01

    Critical temperatures ( T c ) and densities (πc) for aqueous CaCl2 solutions were measured using two different optical techniques, Measurements of T c were made using sealed silica capillaries containing 0,3, 0,5, 1,0, and 2,0 molal CaCl2(aq)) solutions. The T c values from these measurements are 661, 666, 678, and 738 K, respectively. Critical temperatures were also determined from measured homogenization temperatures and the observed mode of homogenization (i.e.. to the liquid or vapor phase or by fading of the meniscus) in synthetic fluid inclusions. Critical temperatures determined by the second method for 1.0, 2.0, and 3.0 molal CaCl2(aq) solutions are 680, 739, and 838 K. respectively. The T c for 4.0 molal CaCl2(aq) was found to be in excess of 933 K, The capillary-tube measurements yield approximate values of the critical density ϱc, but do not give the critical pressure P c Approximate values of T c ,. are available, however, from other sources.

  9. Small amounts of CO2-H2O-rich melt in the lithosphere-asthenosphere.

    NASA Astrophysics Data System (ADS)

    Gaillard, Fabrice; Sifre, David; Hashim, Leila; Hier-Majumder, Saswata

    2014-05-01

    A low viscosity layer at the Lithosphere-Asthenosphere Boundary (LAB) is certainly a requirement for plate tectonics but the nature of the rocks presents in this boundary remains controversial. The seismic low velocities and the high electrical conductivities of the LAB are attributed either to sub-solidus water-related defects in olivine minerals or to a few volume percents of partial melt but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be high enough due to several mineralogical processes that have been so far ignored, including partial melting; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the LAB and by the high melt mobility that can lead to gravitational segregation. All this has long been discussed (30 years ago) when petrologists have defined the petrological LAB as the region of the upper mantle impregnated by incipient melts; that is small amounts of melt caused by small amount of CO2 and H2O. We show here that this incipient melting is a melting regime that is allowed in the entire P-T-fO2 region of the LVZ. The top of the oceanic LVZ (LAB) is best explained by a melt freezing layer due to a decarbonation reaction, whereas the bottom of the LVZ matches the depth at which redox melting defines the lower boundary of stability of incipient melts. Based on new laboratory measurements, we show here that incipient melts must be the cause of the high electrical conductivities in the oceanic LVZ. Considering relevant mantle abundances of H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the LAB for various ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. Incipient melts most likely trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere.

  10. Continuous/Batch Mg/MgH2/H2O-Based Hydrogen Generator

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    A proposed apparatus for generating hydrogen by means of chemical reactions of magnesium and magnesium hydride with steam would exploit the same basic principles as those discussed in the immediately preceding article, but would be designed to implement a hybrid continuous/batch mode of operation. The design concept would simplify the problem of optimizing thermal management and would help to minimize the size and weight necessary for generating a given amount of hydrogen.