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Sample records for 2h2o sintez struktura

  1. Infrared spectroscopy of V2+(H2O) complexes

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, B.; Duncan, M. A.

    2012-03-01

    Doubly charged vanadium-water complexes are produced by laser vaporization in a pulsed supersonic expansion. Size-selected ions are studied with infrared photodissociation spectroscopy in the O-H stretch region using argon complex predissociation. Density functional theory calculations provide structures and vibrational spectra of these ions. The O-H stretches of V2+(H2O) appear at lower frequencies than those of the free water molecule or V+(H2O). The symmetric stretch is more intense than the asymmetric stretch in both V+(H2O) and V2+(H2O) complexes. Spectra of V2+(H2O)Arn (n = 2-7) show that the coordination of the V2+ is filled with six ligands, i.e. one water and five argon atoms.

  2. Thermal decomposition of (UO2)O2(H2O)2·2H2O: Influence on structure, microstructure and hydrofluorination

    NASA Astrophysics Data System (ADS)

    Thomas, R.; Rivenet, M.; Berrier, E.; de Waele, I.; Arab, M.; Amaraggi, D.; Morel, B.; Abraham, F.

    2017-01-01

    The thermal decomposition of uranyl peroxide tetrahydrate, (UO2)O2(H2O)2.2H2O, was studied by combining high temperature powder X-ray diffraction, scanning electron microscopy, thermal analyses and spectroscopic techniques (Raman, IR and 1H NMR). In situ analyses reveal that intermediates and final uranium oxides obtained upon heating are different from that obtained after cooling at room temperature and that the uranyl precursor used to synthesize (UO2)O2(H2O)2·2H2O, sulfate or nitrate, has a strong influence on the peroxide thermal behavior and morphology. The decomposition of (UO2)O2(H2O)2·2H2O ex sulfate is pseudomorphic and leads to needle-like shaped particles of metastudtite, (UO2)O2(H2O)2, and UO3-x(OH)2x·zH2O, an amorphous phase found in air in the following of (UO2)O2(H2O)2 dehydration. (UO2)O2(H2O)2·2H2O and the compounds resulting from its thermal decomposition are very reactive towards hydrofluorination as long as their needle-like morphology is kept.

  3. Accumulation of 2H2O in plasma and eccrine sweat during exercise-heat stress.

    PubMed

    Armstrong, Lawrence E; Klau, Jennifer F; Ganio, Matthew S; McDermott, Brendon P; Yeargin, Susan W; Lee, Elaine C; Maresh, Carl M

    2010-02-01

    The purpose of this research was to characterize the movement of ingested water through body fluids, during exercise-heat stress. Deuterium oxide ((2)H(2)O) accumulation in plasma and eccrine sweat was measured at two sites (back and forehead). The exercise of 14 males was controlled via cycle ergometry in a warm environment (60 min; 28.7 degrees C, 51%rh). Subjects consumed (2)H(2)O (0.15 mg kg(-1), 99.9% purity) mixed in flavored, non-caloric, colored water before exercise, then consumed 3.0 ml kg(-1) containing no (2)H(2)O every 15 min during exercise. We hypothesized that water transit from mouth to skin would occur before 15 min. (2)H(2)O appeared rapidly in both plasma and sweat (P < 0.05), within 10 min of water consumption. The ratio (2)H(2)O/H(2)O (D:H) was 47.3-55.0 times greater in plasma than in back sweat at minutes 10, 20, and 30 (DeltaD:H relative to baseline). At elapsed minute 20, the mean rate of deuterium accumulation (DeltaD:H min(-1)) in plasma was 14.9 and 23.7 times greater than in forehead and back sweat samples, respectively. Mean (+/-SE) whole-body sweat rate was 1.04 +/- 0.05 L h(-1) and subjects with the greatest whole-body sweat rate exhibited the greatest peak deuterium enrichment in sweat (r(2) = 0.87, exponential function); the peak (2)H(2)O enrichment in sweat was not proportional (P > 0.05) to body mass, volume of the deuterium dose, or total volume of fluid consumed. These findings clarify the time course of fluid movement from mouth to eccrine sweat glands, and demonstrate considerable differences of (2)H(2)O enrichment in plasma versus sweat.

  4. SO2:H2O surface complex found at the vapor/water interface.

    PubMed

    Tarbuck, Teresa L; Richmond, Geraldine L

    2005-12-07

    A weakly bonded SO2:H2O surface complex is found at the vapor/water interface prior to the reaction and dissolution of SO2 into the aqueous phase. The results have important implications for understanding the formation of atmospheric aerosols and understanding the atmospheric sulfur cycle.

  5. 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.

  6. 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.

  7. 2Q NMR of 2H2O ordering at solid interfaces

    NASA Astrophysics Data System (ADS)

    Krivokhizhina, Tatiana V.; Wittebort, R. J.

    2014-06-01

    Solvent ordering at an interface can be studied by multiple-quantum NMR. Quantitative studies of 2H2O ordering require clean double-quantum (2Q) filtration and an analysis of 2Q buildup curves that accounts for relaxation and, if randomly oriented samples are used, the distribution of residual couplings. A pulse sequence with absorption mode detection is extended for separating coherences by order and measuring relaxation times such as the 2Q filtered T2. Coherence separation is used to verify 2Q filtration and the 2Q filtered T2 is required to extract the coupling from the 2Q buildup curve when it is unresolved. With our analysis, the coupling extracted from the buildup curve in 2H2O hydrated collagen was equivalent to the resolved coupling measured in the usual 1D experiment and the 2Q to 1Q signal ratio was in accord with theory. Application to buildup curves from 2H2O hydrated elastin, which has an unresolved coupling, revealed a large increase in the 2Q signal upon mechanical stretch that is due to an increase in the ordered water fraction while changes in the residual coupling and T2 are small.

  8. Total lattice potential energy of sodium bromide dihydrate NaBr · 2H 2O

    NASA Astrophysics Data System (ADS)

    Herzig, P.; Jenkins, H. D. B.; Pritchett, M. S. F.

    1984-08-01

    In addition to presenting comparative calculations by two approaches for the total lattice potential energy of sodium bromide dihydrate, NaBr · 2H 2O, found to take the value 803.9 kJ mol -1, we investigate the influence of the size and nature of the basis set used to generate multipole moments in a Hartee-Fock calculation which are in turn used to calculate the Madelung constant. The requirement is one of critical size of the basis set and once this is reached the electrostatic energy will be reliable.

  9. 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.

  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. 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.

  12. New Ni(II)-sulfonamide complexes: synthesis, structural characterization and antibacterial properties. X-ray diffraction of [Ni(sulfisoxazole)2(H2O)4].2H2O and [Ni(sulfapyridine)2].

    PubMed

    Mondelli, Melina; Bruné, Verónica; Borthagaray, Graciela; Ellena, Javier; Nascimento, Otaciro R; Leite, Clarice Q; Batista, Alzir A; Torre, María H

    2008-02-01

    The synthesis, structural characterization, voltammetric experiments and antibacterial activity of [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O and [Ni(sulfapyridine)(2)] were studied and compared with similar previously reported copper complexes. [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O crystallized in a monoclinic system, space group C2/c where the nickel ion was in a slightly distorted octahedral environment, coordinated with two sulfisoxazole molecules through the heterocyclic nitrogen and four water molecules. [Ni(sulfapyridine)(2)] crystallized in a orthorhombic crystal system, space group Pnab. The nickel ion was in a distorted octahedral environment, coordinated by two aryl amine N from two sulfonamides acting as monodentate ligands and four N atoms (two sulfonamidic N and two heterocyclic N) from two different sulfonamide molecules acting as bidentate ligands. Differential pulse voltammograms were recorded showing irreversible peaks at 1040 and 1070 mV, respectively, attributed to Ni(II)/Ni(III) process. [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O and [Ni(sulfapyridine)(2)] presented different antibacterial behavior against Staphylococcus aureus and Escherichia coli from the similar copper complexes and they were inactive against Mycobacterium tuberculosis.

  13. 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

  14. Morphology-defined interaction of copper phthalocyanine with O2/H2O

    DOE PAGES

    Muckley, Eric S.; Miller, Nicholas; Jacobs, Christopher B.; ...

    2016-11-01

    Copper phthalocyanine (CuPc) is an important hole transport layer for organic photovoltaics (OPVs), but its interaction with ambient gas/vapor may lead to changes in electronic properties of the material which subsequently limits the lifetime of OPV devices. CuPc films of thickness 25 nm and 100 nm were grown by thermal sublimation at 25°C, 150°C, and 250°C in order to vary morphology. Using a source-measure unit and a quartz crystal microbalance (QCM), we measured changes in electrical resistance and film mass in situ during exposure to controlled pulses of O2 and H2O vapor. Mass loading by O2 was enhanced by amore » factor of 5 in films deposited at 250 C, possibly due to the ~200° C CuPc -> transition which allows higher O2 mobility between stacked molecules. While gas/vapor sorption occurred over timescales of < 10 minutes, resistance change occurred over timescales > 1 hour, suggesting that mass change occurs by rapid adsorption at active surface sites, whereas resistive response is dominated by slow diffusion of adsorbates into the film bulk. Resistive response generally increases with film deposition temperature due to increased porosity associated with larger crystalline domains. The 25 nm thick films exhibit higher resistive response than 100 nm thick films after an hour of O2/H2O exposure due to the smaller analyte diffusion length required for reaching the film/electrode interface. We found evidence of decoupling of CuPc from the gold-coated QCM crystal due to preferential adsorption of O2/H2O molecules on gold, which is consistent with findings of other studies.« less

  15. Ionized state of hydroperoxy radical-water hydrogen-bonded complex: (HO2-H2O)+.

    PubMed

    Joshi, Ravi; Ghanty, Tapan K; Naumov, Sergej; Mukherjee, Tulsi

    2007-12-27

    Ab initio molecular orbital calculations have been employed to characterize the structure and bonding of the (HO2-H2O)+ radical cation system. Geometry optimization of this system was carried out using unrestricted density functional theory in conjunction with the BHHLYP functional and 6-311++G(2df,2p) as well as 6-311++G(3df,3p) basis sets, the second-order Møller-Plesset perturbation (MP2) method with the 6-311++G(3df,3p) basis set, and the couple cluster (CCSD) method with the aug-cc-pVTZ basis set. The effect of spin multiplicity on the stability of the (HO2-H2O)+ system has been studied and also compared with that of oxygen. The calculated results suggest a proton-transferred hydrogen bond between HO2 and H2O in H3O3+ wherein a proton is partially transferred to H2O producing the O2...H3O+ structure. The basis set superposition error and zero-point energy corrected results indicate that the H3O3+ system is energetically more stable in the triplet state; however, the singlet state of H3O3+ is more stable with respect to its dissociation into H3O+ and singlet O2. Since the resulting proton-transferred hydrogen-bonded complex (O2...H3O+) consists of weakly bound molecular oxygen, it might have important implications in various chemical processes and aquatic life systems.

  16. Reactivity of organic complexes at mineral-CO2-H2O interfaces

    NASA Astrophysics Data System (ADS)

    Miller, Q. R.; Schaef, T.; Kaszuba, J. P.; Qiu, L.; Bowden, M. E.; McGrail, B. P.

    2015-12-01

    Understanding the interactions between minerals and organics in H2O-CO2 fluids is important, as they are the two most abundant volatiles in the crust. CO2-rich fluids in natural and anthropogenic environments, such as metamorphic aureoles and carbon storage reservoirs, respectively, produce a complex geochemical setting in which CO2-rich fluids containing dissolved water and organic compounds interact with rocks and minerals. We have undertaken experimental and theoretical studies to evaluate how organics impact carbonate mineralization and to determine the partitioning behavior of organic complexes between CO2, H2O, and mineral interfaces. The first groups of experiments have clarified how the type and concentration of simple organic ligands impact the degree and type of carbonation in interfacial water films. In these experiments, salts of simple organic ligands were equilibrated with wet supercritical CO2, which was reacted with the model mineral forsterite (Mg2SiO4). The forsterite dissolution and coupled carbonate precipitation reactions were followed with time-resolved pressurized X-ray diffraction (XRD) at 50 °C and 90 bar. The extent of carbonation and the relative abundance of anhydrous magnesite (MgCO3) precipitated relative to hydrated nesquehonite (MgCO3·3H2O) was impacted by the type of organic ligand. Magnesite enhancement was observed with the trend of citrate>oxalate≈malonate>acetate>organic-free control. This indicates that the organic ligands complexed Mg2+ in the interfacial water film environment and helped alleviate kinetic barriers to magnesite formation. Additional XRD experiments with varying concentrations of citrate verified the dependence of magnesite enhancement and the degree of overall carbonation on the amount of organic present in the water film. Lastly, our ongoing work concerning the partitioning of organic and metal-organic complexes between CO2, H2O, and interfacial water films will be presented. This experimental work, which

  17. Solubilities of salts in the ternary systems NaCl + CaCl2 + H2O and KCl + CaCl2 + H2O at 75°C

    NASA Astrophysics Data System (ADS)

    Yang, Ji-Min; Liu, Xiao-Lin; Liang, Pei-Pei

    2011-07-01

    The solubility in the NaCl-CaCl2-H2O and KCl-CaCl2-H2O systems were determined at 75°C and the phase diagrams and the diagram of physicochemical property vs composition were plotted. One invariant point, two univariant curves, and two crystallization zones, corresponding to potassium chloride, dihydrate (CaCl2 · 2H2O) showed up in the phase diagrams of the ternary systems. The mixing parameters θM, Ca and ΨM, Ca, Cl (M = Na or K) and equilibrium constant K sp were evaluated in NaCl-CaCl2-H2O and KCl-CaCl2-H2O systems by least-squares optimization procedure, in which the single-salt Pitzer parameters of NaCl, KCl, and CaCl2 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.

  18. High-solids biphasic CO2-H2O pretreatment of lignocellulosic biomass.

    PubMed

    Luterbacher, Jeremy S; Tester, Jefferson W; Walker, Larry P

    2010-10-15

    A high pressure (200 bar) CO(2)-H(2)O process was developed for pretreating lignocellulosic biomass at high-solid contents, while minimizing chemical inputs. Hardwood was pretreated at 20 and 40 (wt.%) solids. Switchgrass, corn stover, big bluestem, and mixed perennial grasses (a co-culture of big bluestem and switchgrass) were pretreated at 40 (wt.%) solids. Operating temperatures ranged from 150 to 250 degrees C, and residence times from 20 s to 60 min. At these conditions a biphasic mixture of an H(2)O-rich liquid (hydrothermal) phase and a CO(2)-rich supercritical phase coexist. Following pretreatment, samples were then enzymatically hydrolyzed. Total yields, defined as the fraction of the theoretical maximum, were determined for glucose, hemicellulose sugars, and two degradation products: furfural and 5-hydroxymethylfurfural. Response surfaces of yield as a function of temperature and residence time were compared for different moisture contents and biomass species. Pretreatment at 170 degrees C for 60 min gave glucose yields of 77%, 73%, and 68% for 20 and 40 (wt.%) solids mixed hardwood and mixed perennial grasses, respectively. Pretreatment at 160 degrees C for 60 min gave glucan to glucose yields of 81% for switchgrass and 85% for corn stover.

  19. Spatial structures of CO2, H2O, temperature and vertical wind velocity observed by aircraft

    NASA Astrophysics Data System (ADS)

    Selbach, Christoph; Schween, Jan; Crewell, Susanne; Geiss, Heiner; Neininger, Bruno

    2010-05-01

    During the FLUXPAT campaigns in 2008 and 2009 the MetAir Dimona research aricraft performed several fligths above a patchy, agricultural dominated landscape near Juelich/Germany. The measurements are aimed to capture the variability of water vapor and CO2 and derive turbulent fluxes in the atmospheric boundary layer close to the ground. Flights took place at two main levels around 150 m and 250 m above ground. Agriculture in this region is dominated by two different crops: sugar beet and wheat. Flights were scheduled in April and August as at these times of the year strong contrasts can be found between different fields. In April sugar beet is usually just seeded whereas wheat already forms a closed canopy. In August wheat unlike sugar beat is already harvested. We analyse the correlation lengths (L*) of CO2, H2O, temperature and vertical wind velocity on flight legs. L* is the median of the power spectrum i.e. 50 percent of the variance is in structures larger than L*. For the different quantities L* shows different behaviours during the day and between different flight levels. The structure lengthscales of CO2 have a large dependency on daytime and strongly decrease during noon and afternoon. We will present some approaches to explain this behaviour.

  20. 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.

  1. 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.

  2. 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

  3. High pressure-temperature Raman spectroscopy of H2-H2O clathrate.

    NASA Astrophysics Data System (ADS)

    Somayazulu, Maddury; Levedahl, Alexander; Goncharov, Alexander; Mao, Ho-Kwang; Hemley, Russell

    2007-03-01

    The melting curve of the C2 clathrate H2-H2O has been determined by in-situ Raman spectroscopy measurements in an externally heated diamond anvil cell. We have determined the melting curve to a maximum pressure of 27 GPa. These are the first measurements on the melting line in this clathrate. Depending on the stoichiometry of the starting mixture of H2 and H2O, we are able to study either a mixture of C2 and H2O or C2 and H2. In either case, we were able to pinpoint the melting of the clathrate from the measurements of the molecular stretching mode (vibron) in the clathrate. In the case of C2 + Ice VII, we observe the vibron in the clathrate at a frequency higher than in pure H2 at the same pressure. We have cross-calibrated the melting temperatures using the Stokes-anti Stokes ratio of the diamond first order and Raman active TO phonon of cubic Boron Nitride. We find that the clathrate melts well above the H2 melting at all pressures studied indicating that the stabilization of this clathrate at high pressures is indeed due to interactions between the host and guest molecules.

  4. 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.

  5. 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.

  6. Hydrogen isotope systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Kawagucci, S.; Hattori, S.; Yamada, K.; Ueno, Y.; Takai, K.; Yoshida, N.

    2011-12-01

    Hydrogen and carbon isotopes of CH4 have been utilized to trace microbial processes. The isotope fractionations during hydrogenotrophic methanogenesis, one of the major processes of environmental CH4, have been studied by several laboratory incubations. For the carbon isotope, H2 concentration is thought to be the major parameter controlling the carbon isotope fractionation by hydrogenotrophic methanogenesis. For the hydrogen, on the other hand, factors controlling isotope fractionation remain poorly understood, although H2 concentration is suggested to be important. This uncertainty prevents us to utilize δD-CH4 value as the tracer. The most important and principal question is whether all hydrogen atoms in microbially-generated CH4 come from environmental H2O or not. To answer the question, we investigated the D/H systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis by pure culture incubation with softly deuterium-enriched H2 and/or H2O. Our results demonstrate that δD-CH4 value produced by hydrogenotrophic methanogens depends not only on δD-H2O value but also on δD-H2 value. We observed constant correlation between δD-H2 and δD-CH4 values as well as between δD-H2O and δD-CH4 values, which suggests that hydrogen (/deuterium) atom of substrate H2 is also transferred to the product CH4. This implies that the range of δD-CH4 value produced by hydrogenotrophic methanogenesis should be re-evaluated considering the distribution of δD-H2 and δD-H2O values in natural environments.

  7. Monte Carlo simulations of high-pressure phase equilibria of CO2-H2O mixtures.

    PubMed

    Liu, Yang; Panagiotopoulos, Athanassios Z; Debenedetti, Pablo G

    2011-05-26

    Histogram-reweighting grand canonical Monte Carlo simulations were used to obtain the phase behavior of CO(2)-H(2)O mixtures over a broad temperature and pressure range (50 °C ≤ T ≤ 350 °C, 0 ≤ P ≤ 1000 bar). We performed a comprehensive test of several existing water (SPC, TIP4P, TIP4P2005, and exponential-6) and carbon dioxide (EPM2, TraPPE, and exponential-6) models using conventional Lorentz-Berthelot combining rules for the unlike-pair parameters. None of the models we studied reproduce adequately experimental data over the entire temperature and pressure range, but critical assessments were made on the range of T and P where particular model pairs perform better. Away from the critical region (T ≤ 250 °C), the exponential-6 model combination yields the best predictions for the CO(2)-rich phase, whereas the TraPPE/TIP4P2005 model combination provides the most accurate coexistence composition and pressure for the H(2)O-rich phase. Near the critical region (250 °C < T ≤ 350 °C), the critical points are not accurately estimated by any of the models studied, but the exponential-6 models are able to qualitatively capture the critical loci and the shape of the phase envelopes. Local improvements can be achieved at specific temperatures by introducing modification factors to the Lorentz-Berthelot combining rules, but the modified combining rule is still not able to achieve global improvements over the entire temperature and pressure range. Our work points to the challenge and importance of improving current atomistic models so as to accurately predict the phase behavior of this important binary mixture.

  8. Redetermination of metarossite, CaV5+ 2O6·2H2O

    PubMed Central

    Kobsch, Anaïs; Downs, Robert T.; Domanik, Kenneth J.

    2016-01-01

    The crystal structure of metarossite, ideally CaV2O6·2H2O [chemical name: calcium divanadium(V) hexa­oxide dihydrate], was first determined using precession photographs, with fixed isotropic displacement parameters and without locating the positions of the H atoms, leading to a reliability factor R = 0.11 [Kelsey & Barnes (1960 ▸). Can. Mineral. 6, 448–466]. This communication reports a structure redetermination of this mineral on the basis of single-crystal X-ray diffraction data of a natural sample from the Blue Cap mine, San Juan County, Utah, USA (R1 = 0.036). Our study not only confirms the structural topology reported in the previous study, but also makes possible the refinement of all non-H atoms with anisotropic displacement parameters and all H atoms located. The metarossite structure is characterized by chains of edge-sharing [CaO8] polyhedra parallel to [100] that are themselves connected by chains of alternating [VO5] trigonal bipyramids parallel to [010]. The two H2O mol­ecules are bonded to Ca. Analysis of the displacement parameters show that the [VO5] chains librate around [010]. In addition, we measured the Raman spectrum of metarossite and compared it with IR and Raman data previously reported. Moreover, heating of metarossite led to a loss of water, which results in a transformation to the brannerite-type structure, CaV2O6, implying a possible dehydration pathway for the compounds M 2+V2O6·xH2O, with M = Cu, Cd, Mg or Mn, and x = 2 or 4. PMID:27920917

  9. Infrared Absorption in Partially Disordered K2CuCl4·2H2O-TYPE Compounds

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, M. A.; Grado-Caffaro, M.

    An approximate relationship for the coefficient of optical absorption valid, in principle, for the infrared range, corresponding to K2CuCl4·2H2O-type compounds is derived from a model for electronic density of states. These compounds are assumed to be partially disordered from the point of view of the general theory of solids.

  10. Synthesis, structure, and properties of the noncentrosymmetric hydrated borate Na(2)B(5)O(8)(OH).2H(2)O.

    PubMed

    Wang, Yongjiang; Pan, Shilie; Tian, Xuelin; Zhou, Zhongxiang; Liu, Gang; Wang, Jide; Jia, Dianzeng

    2009-08-17

    Single crystal of hydrated sodium borate Na(2)B(5)O(8)(OH).2H(2)O has been grown with sizes up to 5 x 5 x 3 mm(3) under mild hydrothermal conditions at 180 degrees C. The structure is determined by single-crystal X-ray diffraction and further characterized by IR and TG analyses. It crystallizes in the orthorhombic space group Pna2(1), with a = 11.967(2) A, b = 6.5320(13) A, c = 11.126(2) A, Z = 4, R1 = 0.0183, and wR2 = 0.0483. The crystal structure of Na(2)B(5)O(8)(OH).2H(2)O is made up of Na-O polyhedra, and [B(5)O(8)(OH)](2-) polyborate anions. Transmittance spectrum is performed on the Na(2)B(5)O(8)(OH).2H(2)O crystal, which shows an absorption edge less than 190 nm in the UV region. The powder second-harmonic generation intensity measured by the Kurtz-Perry method indicates that Na(2)B(5)O(8)(OH).2H(2)O is about half that of KH(2)PO(4) (KDP).

  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.

  12. Oxidative degradation of dyes in water using Co2+/H2O2 and Co2+/peroxymonosulfate.

    PubMed

    Ling, Sie King; Wang, Shaobin; Peng, Yuelian

    2010-06-15

    Dye degradation using advanced oxidation processes with Co(2+)/H(2)O(2) and Co(2+)/peroxymonosulfate (PMS) systems has been investigated. Two types of dyes, basic blue 9 and acid red 183, were employed. Several parameters affecting dye degradation such as Co(2+), PMS, H(2)O(2), and dye concentrations were investigated. The optimal ratio of oxidant (PMS, H(2)O(2))/Co(2+) for the degradation of two dyes was determined. It is found that dye decomposition is much faster in Co(2+)/PMS system than in Co(2+)/H(2)O(2). For Co(2+)/H(2)O(2), an optimal ratio of H(2)O(2) to Co(2+) at 6 is required for the maximum decomposition of the dyes. For Co(2+)/PMS, higher concentrations of Co(2+) and PMS will increase dye degradation rate with an optimal ratio of 3, achieving 95% decolourisation. For basic blue 9, a complete decolourisation can be achieved in 5 min at 0.13 mM Co(2+), 0.40 mM PMS and 7 mg/l basic blue 9 while the complete degradation of acid red 183 will be achieved at 30 min at 0.13 mM Co(2+), 0.40 mM PMS and 160 mg/l of acid red 183. The degradation of acid red 183 follows the second-order kinetics.

  13. 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

  14. The effect of coordinated water on the connectivity of uranium(IV) sulfate x-hydrate: [U(SO4)2(H2O)5]·H2O and [U(SO4)2(H2O)6]·2H2O, and a comparison with other known structures.

    PubMed

    Burns, Alexander D; Patrick, Brian O; Lam, Anita E; Dreisinger, David

    2014-07-01

    Two new solid-state uranium(IV) sulfate x-hydrate complexes (where x is the total number of coordinated plus solvent waters), namely catena-poly[[pentaaquauranium(IV)]-di-μ-sulfato-κ(4)O:O'] monohydrate], {[U(SO4)2(H2O)5]·H2O}n, and hexaaquabis(sulfato-κ(2)O,O')uranium(IV) dihydrate, [U(SO4)2(H2O)6]·2H2O, have been synthesized, structurally characterized by single-crystal X-ray diffraction and analyzed by vibrational (IR and Raman) spectroscopy. By comparing these structures with those of four other known uranium(IV) sulfate x-hydrates, the effect of additional coordinated water molecules on their structures has been elucidated. As the number of coordinated water molecules increases, the sulfate bonds are displaced, thus changing the binding mode of the sulfate ligands to the uranium centre. As a result, uranium(IV) sulfate x-hydrate changes from being fully crosslinked in three dimensions in the anhydrous compound, through sheet and chain linking in the tetra- and hexahydrates, to fully unlinked molecules in the octa- and nonahydrates. It can be concluded that coordinated waters play an important role in determining the structure and connectivity of U(IV) sulfate complexes.

  15. Comparative study of the degradation of real textile effluents by photocatalytic reactions involving UV/TiO2/H2O2 and UV/Fe2+/H2O2 systems.

    PubMed

    Garcia, J C; Oliveira, J L; Silva, A E C; Oliveira, C C; Nozaki, J; de Souza, N E

    2007-08-17

    This work investigated the treatability of real textile effluents using several systems involving advanced oxidation processes (AOPs) such as UV/H2O2, UV/TiO2, UV/TiO2/H2O2, and UV/Fe2+/H2O2. The efficiency of each technique was evaluated according to the reduction levels observed in the UV absorbance of the effluents, COD, and organic nitrogen reduction, as well as mineralization as indicated by the formation of ammonium, nitrate, and sulfate ions. The results indicate the association of TiO2 and H2O2 as the most efficient treatment for removing organic pollutants from textile effluents. In spite of their efficiency, Fenton reactions based treatment proved to be slower and exhibited more complicated kinetics than the ones using TiO2, which are pseudo-first-order reactions. Decolorization was fast and effective in all the experiments despite the fact that only H2O2 was used.

  16. 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

    2012-08-06

    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.

  17. Muon spin relaxation study of Zr(H2PO4)(PO4).2H2O.

    PubMed

    Clayden, Nigel J; Cottrell, Stephen P

    2006-07-14

    Muon spin relaxation has been used to study the muon dynamics in the layered zirconium phosphate Zr(H(2)PO(4))(PO(4)).2H(2)O as a function of temperature. Radiofrequency decoupling was used to establish the origin of the local dipolar field as coupling with (1)H spins. Muons were trapped at two sites, one identified as HMuO and the other consistent with PO-Mu on the basis of their zero-field second moments. Although a small decrease in the local nuclear dipolar field was seen with temperature, the muons remained essentially static over the temperature range 20-300 K.

  18. Two-temperature stage biphasic CO2-H2O pretreatment of lignocellulosic biomass at high solid loadings.

    PubMed

    Luterbacher, Jeremy S; Tester, Jefferson W; Walker, Larry P

    2012-06-01

    Most biomass pretreatment processes for monosaccharide production are run at low-solid concentration (<10 wt%) and use significant amounts of chemical catalysts. Biphasic CO(2) -H(2) O mixtures could provide a more sustainable pretreatment medium while using high-solid contents. Using a stirred reactor for high solids (40 wt%, biomass water mixture) biphasic CO(2)-H(2) O pretreatment of lignocellulosic biomass allowed us to explore the effects of particle size and mixing on mixed hardwood and switchgrass pretreatment. Subsequently, a two-temperature stage pretreatment was introduced. After optimization, a short high-temperature stage at 210°C (16 min for hardwood and 1 min for switchgrass) was followed by a long low-temperature stage at 160°C for 60 min. Glucan to glucose conversion yields of 83% for hardwood and 80% for switchgrass were obtained. Total molar sugar yields of 65% and 55% were obtained for wood and switchgrass, respectively, which consisted of a 10% points improvement over those obtained during our previous study despite a 10-fold increase in particle size. These yields are similar to those obtained with other major pretreatment technologies for wood and within 10% of major technologies for switchgrass despite the absence of chemical catalysts, the use of large particles (0.95 cm) and high solid contents (40 wt%).

  19. Kinetics of HO2 + HO2 -> H2O2 + O2: Implications for Stratospheric H2O2

    NASA Astrophysics Data System (ADS)

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Salawitch, R. J.; Toon, G. C.; Sen, B.; Blavier, J.-F.; Jucks, K. W.

    2002-05-01

    The reaction HO2 + HO2 -> H2O2 + O2(1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl2/CH3OH/O2/N2 and F2/H2/O2/N2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k1 = (8.8 +/- 0.9) 10-13 × exp[(210 +/- 26)/T] cm3 molecule-1 s-1 (2σ uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k1, which includes the dependence on bath gas density, is k1 = (1.5 +/- 0.2) × 10-12 × exp[(19 +/- 31)/T] + 1.7 × 10-33 × [M] × exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere.

  20. Optimization of photocatalytic degradation of biodiesel using TiO2/H2O2 by experimental design.

    PubMed

    Ambrosio, Elizangela; Lucca, Diego L; Garcia, Maicon H B; de Souza, Maísa T F; de S Freitas, Thábata K F; de Souza, Renata P; Visentainer, Jesuí V; Garcia, Juliana C

    2017-03-01

    This study reports on the investigation of the photodegradation of biodiesel (B100) in contact with water using TiO2/H2O2. The TiO2 was characterized by X-ray diffraction analysis (XRD), pH point of zero charge (pHpzc) and textural analysis. The results of the experiments were fitted to a quadratic polynomial model developed using response surface methodology (RSM) to optimize the parameters. Using the three factors, three levels, and the Box-Behnken design of experiment technique, 15 sets of experiments were designed considering the effective ranges of the influential parameters. The responses of those parameters were optimized using computational techniques. After 24h of irradiation under an Hg vapor lamp, removal of 22.0% of the oils and greases (OG) and a 33.54% reduction in the total of fatty acid methyl ester (FAME) concentration was observed in the aqueous phase, as determined using gas chromatography coupled with flame ionization detection (GC/FID). The estimate of FAMEs undergo base-catalyzed hydrolysis is at least 3years (1095days) and after photocatalytic treatment using TiO2/H2O2, it was reduced to 33.54% of FAMEs in only 1day.

  1. [Cryogenic Raman spectroscopic studies in the system of NaCl-MgCl2-H2O].

    PubMed

    Yang, Dan; Xu, Wen-Yi

    2010-03-01

    In the present paper, the best experimental conditions for producing hydrates in the NaCl-H2O and MgCl2-H2O systems were found through the cryogenic Raman spectroscopy. This experimental condition is rapidly cooling to -180 degrees C and slowly warming to observe hydrate formation process (that is manifested as a darkening of the vision in the microscope), and finally, rapidly cooling down to -180 degrees C. Moreover, a qualitative or semiquantitative analytical method for NaCl-MgCl2-H2O system was established. This method is that 3 537 cm(-1) may instruct the existence of NaCl hydrates, 3 514 cm(-1) may instruct the existence of MgCl2 hydrates, and comparison of the intensity of 3 537 and 3 514 cm(-1) peaks can be used to estimate the ratio of NaCl and MgCl2 in the system. All these are the foundations for quantifying the components of natural fluid inclusions. The author supports Samson's idea through observing the phenomenon of experiments in the controversy of the meta-stable eutectics formation model, that is ice forms on initial cooling, leaving a residual, interstitial, hypersaline liquid. On warming, the salt hydrates crystallize from this liquid.

  2. Magnetic Ordering of Antiferromagnetic Trimer System 2b·3CuCl2·2H2O

    NASA Astrophysics Data System (ADS)

    Sanda, M.; Kubo, K.; Asano, T.; Morodomi, H.; Inagaki, Y.; Kawae, T.; Wang, J.; Matsuo, A.; Kindo, K.; Sato, T. J.

    2012-12-01

    In this paper, we present the magnetic properties of 2b·3CuCl2·2H2O (b = betaine, C5H11NO2). 2b·3CuCl2·2H2O is the first model substance for a two-dimensional S = 1/2 orthogonal antiferromagnetic trimer system. We have performed magnetic susceptibility, magnetization curve, and specific heat under extreme conditions: low temperatures and high magnetic fields in this system. The experimental results indicate that this substance is a magnetically S = 1/2 antiferromagnetic trimer system. The magnetization also shows one-third of the saturation value (MS ~ 3.2μB/f.u.) between 5 and 14T The specific heat in a zero field shows a sharp peak at 1.38K corresponding to a long-range magnetic ordering, TN. As the magnetic field increases, the TN shifts remarkably to a lower temperature and is suppressed. Above 5T, the specific heat has no anomaly down to 150mK In the plateau region with an energy gap, the magnetic ordering seems to be disappeared.

  3. Systematic Variations in CO2/H2O Ice Abundance Ratios in Nearby Galaxies Found with AKARI Near-infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Onaka, T.; Shimonishi, T.; Suzuki, T.

    2015-07-01

    We report CO2/H2O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5-5.0 μm) spectra. The CO2/H2O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO2/H2O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO2/H2O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO2/H2O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO2/H2O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO2/H2O ice abundance ratios tend to be high in young star-forming galaxies.

  4. First divalent metal complexes of the polyether ionophore Monensin A: X-Ray structures of [Co(Mon)2(H2O)2] and [Mn(Mon)2(H2O)2] and their bactericidal properties.

    PubMed

    Pantcheva, Ivayla N; Mitewa, Mariana Io; Sheldrick, William S; Oppel, Iris M; Zhorova, Rumyana; Dorkov, Petar

    2008-06-01

    The complexation of carboxylic acid Monensin A (MonH, 1a) with CoCl2.6H2O and MnCl2.4H2O leads to the formation of mononuclear complexes [Co(Mon)2(H2O)2], 2a and [Mn(Mon)2(H2O)2], 2b, respectively. The unique crystal structures of 2a and 2b were determined by X-ray crystallography. The complexes crystallize in the monoclinic space group P2 1 with an octahedrally coordinated transition metal center forming the crystallographically centrosymmetric chromophore CoO6 or MnO6, respectively. Two molecules of Monensin A act bidentately through their carboxylate moiety and a hydroxyl group, and two water molecules are additionally trans-coordinated. Although the transition metal ions are not bound into the cavity of the ligand, the unusual bidentate coordination mode of the ionophore induces its "pseudo-cyclization" forming 22-membered cycles further stabilized by a number of H-bonds. The complexes are the first example of divalent metal complexes of the monovalent polyether ionophore. The parallel study on the complexation ability of the potassium complex of Monensin A (MonK, 1b) towards Co(II) and Mn(II) showed the formation of the isostructural complexes 2a and 2b accompanied by loss of the potassium ion due to the new coordination mode of the ligand. The biological tests performed with the antibiotic MonH and the corresponding metal(II) complexes show greatly enhanced antimicrobial activity of complexes 2a-b against Gram(+)-bacteria.

  5. Crystal structure and vibrational spectra of BaH 4I 2O 10·2H 2O

    NASA Astrophysics Data System (ADS)

    Haeuseler, H.; Wagener, M.

    2008-12-01

    By crystallization from strongly acidic aqueous solutions barium-tetrahydrogen-decaoxodiperiodate-dihydrate, BaH 4I 2O 10·2H 2O has been obtained (S.G. C2/ c, No. 15) with the lattice constants a = 12.728(3), b = 7.987(2), c = 9.459(2), and β = 94.07(3). IR and Raman spectra are given and analysed with respect to the internal vibrations of the HIO102- ion and the hydrogen bond system. According to high temperature Raman spectra and DTA and TG measurements, the compound decomposes via unknown salts with the anion IO4- above 230 °C to the corresponding iodate which above 575 °C starts to disproportionate to the periodate Ba 5(IO 6) 2.

  6. 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.

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

    PubMed

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

    2015-08-03

    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.

  8. 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.

  9. 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.

  10. Bis(ethylenediammonium) decaaquadisodium decavanadate, (C2H10N2)2[Na2(H2O)10][V10O28].

    PubMed

    Li, Guo Bao; Yang, Si Hai; Xiong, Ming; Lin, Jian Hua

    2004-12-01

    In the title compound, the decavanadate anion, [V(10)O(28)](6-), and the bridged [Na(2)(H(2)O)(10)](2+) dication lie across inversion centers. The charge balance is achieved by ethylenediammonium cations, H(3)NCH(2)CH(2)NH(3)(2+), which are disordered. The decavanadate anions are surrounded by the [Na(2)(H(2)O)(10)](2+) dications, thus forming layers, and the ethylenediammonium cations are located between these layers.

  11. Equations of state for H2, H2O, and H2-H2O fluid mixtures at temperatures above 0.01° C and at high pressures

    NASA Astrophysics Data System (ADS)

    Rimbach, Helmut; Chatterjee, Niranjan D.

    1987-11-01

    Modified Redlich-Kwong (MRK) equations of state have been derived for the pure fluid species H2 and H2O by expressing the parameter a as a function of T and P, and b as as a function of P only. These equations are valid above 0° and 0.01° C, respectively. For H2O, the prediction of volumes is successful not only in the supercritical, but also in the subcritical range. As a result of this, the saturation curve of H2O can be calculated with a maximum deviation of ±1.4 bar in the range 100 350° C. Between 350° C and the critical point (374.15° C), the uncertainty increases somewhat; this is due to a fundamental inadequacy of the Redlich-Kwong equation itself. These equations of state permit extrapolations to pressures of 100 kbar for H2 and at least 200 kbar for H2O and are, therefore, eminently suited for geochemical applications. Formulation of the MRK of the binary H2-H2O mixtures was achieved by assuming the quadratic mixing rule for the parameters a mix and b+mix. To derive the cross coefficients, aH2-H2Oand b H 2-H 2O, adjustable corrective factors ɛ and τ had to be introduced. The T- and P-dependences of ɛ and τ are based on P-V-T-X H 2 data (Seward and Franck 1981) to 440° C and 2500 bar. The resulting equation of state very satisfactorily reproduces the volumes observed experimentally at various sets of T, P, and X H 2. At a total pressure of 2 kbar, positive deviation from ideal mixing behaviour is still perceptible at as high a temperature as 1000° C. At some temperature around 380° C, phase separation sets in, an aqueous solution with dissolved H2 coexisting in equilibrium with an H2-rich fluid with dissolved H2O. The computed P-T-X H 2 surface of this two-phase region agrees well with that observed in Seward and Franck's (1981) experiments. An independent proof of the validity of this equation of state is the accuracy with which H {m/ex}can be predicted. Calorimetric measurements of H {m/ex}(Smith et al. 1983, Wormald and Colling 1985

  12. Influence of Ar/O2/H2O Feed Gas and N2/O2/H2O Environment on the Interaction of Time Modulated MHz Atmospheric Pressure Plasma Jet (APPJ) with Model Polymers

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb; Luan, Pingshan; Knoll, Andrew; Kondeti, Santosh; Bruggeman, Peter

    2016-09-01

    An Ar/O2/H2O fed time modulated MHz atmospheric pressure plasma jet (APPJ) in a sealed chamber was used to study plasma interaction with model polymers (polystyrene, poly-methyl methacrylate, etc.). The amount of H2O in the feed gas and/or present in the N2, O2, or N2/O2 environment was controlled. Short lived species such as O atoms and OH radicals play a crucial role in polymer etching and surface modifications (obtained from X-ray photoelectron spectroscopy of treated polymers without additional atmospheric exposure). Polymer etching depth for Ar/air fed APPJ mirrors the decay of gas phase O atoms with distance from the APPJ nozzle in air and is consistent with the estimated O atom flux at the polymer surface. Furthermore, whereas separate O2 or H2O admixture to Ar enhances polymer etching, simultaneous addition of O2 and H2O to Ar quenches polymer etching. This can be explained by the mutual quenching of O with OH, H and HO2 in the gas phase. Results where O2 and/or H2O in the environment were varied are consistent with these mechanisms. All results will be compared with measured and simulated species densities reported in the literature. We gratefully acknowledge funding from US Department of Energy (DE-SC0001939) and National Science Foundation (PHY-1415353).

  13. Effect of CO2 on the Second Critical Endpoint in the System Peridotite-CO2-H2O (Invited)

    NASA Astrophysics Data System (ADS)

    Mibe, K.; Kawamoto, T.; Ono, S.

    2009-12-01

    Under high pressure and temperature conditions, it is known that aqueous fluid and hydrous silicate melt become completely miscible and form supercritical fluid in the system peridotite-H2O [Mibe et al., 2007 JGR]. Because some amounts of CO2 are thought to be present in the Earth’s interior, it is important to clarify the effect of CO2 on the second critical endpoint in the system peridotite-CO2-H2O in order to understand the magmatism and mass transport in the Earth’s mantle. Experiments were conducted using X-ray radiography technique together with Kawai-type double-stage multi-anvil high pressure apparatus (SPEED-1500) installed at SPring-8, Japan. Direct X-ray beam, which passes through the anvil gaps of SPEED-1500 and sample under high pressure, is observed with an X-ray camera. We used a sample container which is composed of a AuPd tube and a pair of single crystal diamond lids put on both ends of AuPd tube. The sample was prepared by mixing hydroxides, carbonates, silicate glass, and water. The molar ratio of H2O (XH2O = H2O/(H2O + CO2)) in the starting material is about 0.92 to 0.94. The experimental conditions are at pressures from 2.0 to 4.0 GPa and at temperatures up to about 1400 deg. C. Pressure is applied first, and then temperature is increased. In the experiments up to 3.5 GPa, both aqueous fluid and silicate melt were observed. Above 3.5 GPa, however, we could not distinguish two phases in the radiographic images, indicating that aqueous fluid and silicate melt can coexist up to 3.5 GPa and there is no difference between these two phases above 3.5 GPa. From these observations, it can be concluded that the second critical endpoint in the system peridotite-CO2-H2O occurs at around 3.5 GPa. Our previous results [Mibe et al., 2007 JGR] in the system peridotite-H2O (i.e., CO2-free system) showed that the second critical endpoint occurred at around 3.8 GPa. Therefore, it is revealed that the addition of CO2 to the system causes the reduction of

  14. Study on photoacoustic phase spectrum of rare earth complex: Pr(HFA) 3·2H 2O

    NASA Astrophysics Data System (ADS)

    Qinglu, Mao; Qingde, Su; Guiwen, Zhao

    1996-06-01

    The β-diketone rare earth complex: Pr(HFA) 3·2H 2O was synthesized and its amplitude and phase photoacoustic spectra in the range of 300-700 nm were reported. It was observed that the phase angle depends variously on the relaxation time τ and the optical absorption coefficient β with the incident light wavelength λ. A model of a homogeneous powder sample containing multiple optical absorption bands based on the Mandelis work was introduced to interpret the phase spectrum. It is shown that this model is very suitable for explaining the phase data associated with the π-π∗ transition and tf-tf transitions of the title complex. The phase angle ψ is mainly related to τ for the π-π∗ transition while it is determined by β for the tf-tf transition at relatively low chopping frequencies. Furthermore, the dependence of amplitude and phase information on the chopping frequency was also investigated.

  15. Magnesium cinnamate complex, [Mg(cinn)2(H2O)2]n; structural, spectroscopic, thermal, biological and pharmacokinetical characteristics

    NASA Astrophysics Data System (ADS)

    Puszyńska-Tuszkanow, Mariola; Zierkiewicz, Wiktor; Grabowski, Tomasz; Daszkiewicz, Marek; Maciejewska, Gabriela; Adach, Anna; Kucharska-Ziembicka, Katarzyna; Wietrzyk, Joanna; Filip-Psurska, Beata; Cieślak-Golonka, Maria

    2017-04-01

    The composition and structure of the magnesium complex with cinnamic acid, [Mg(cinn)2(H2O)2]n(1), were determined using single crystal X-ray diffraction data, IR, NMR spectroscopies, thermal and mass spectrometry analysis. Magnesium cinnamate complex, like the isostructural cobalt(II) species reported in the literature, appears to belong to the group of coordination polymers forming layered solids with pseudooctahedral coordination around the metal centre and Osbnd Csbnd O bridging units. The vibrational assignments of the experimental spectra of the complex (1) were performed on the basis of the DFT results obtained for the [Mg(cinn)4(H2O)2]2- ion, serving as a model. The complex was found to exhibit a very low cytotoxicity against neoplastic: A549 (lung), MCF-7 (breast), P388 (murine leukemia) and normal BALB3T3 (mouse fibroblasts) cell lines. In silico pharmacokinetical parameter calculations for (1) and seven known magnesium complexes with carboxylic acids: lactic, malic, glutamic, hydroaspartic and aspartic allowed for comparison of their potential bioavailability. Magnesium cinnamate complex appeared to exhibit a superior lipophilic property that suggests an optimal pharmacokinetics profile.

  16. 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.

  17. 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.

  18. [Zn3(PO4)2(H2O)(0.8)(NH3)(1.2)].

    PubMed

    Stojanović, Jovica; Dordević, Tamara; Karanović, Ljiljana

    2010-05-01

    The structure of the title compound, ammineaquadi-mu(5)-phosphato-trizinc(II), [Zn(3)(PO(4))(2)(H(2)O)(0.8)(NH(3))(1.2)], consists of two parts: (i) PO(4) and ZnO(4) vertex-sharing tetrahedra arranged in layers parallel to (100) and (ii) ZnO(2)(N/O)(2) tetrahedra located between the layers. Elemental analysis establishes the ammine-to-water ratio as 3:2. ZnO(2)(N/O)(2) tetrahedra are located at special position 4e (site symmetry 2) in C2/c. The two O atoms of ZnO(2)(N/O)(2) are bonded to neighbouring P atoms, forming two Zn-O-P linkages and connecting ZnO(2)(N/O)(2) tetrahedra with two adjacent bc plane layers. A noteworthy feature of the structure is the presence of NH(3) and H(2)O at the same crystallographic position and, consequently, qualitative changes in the pattern of hydrogen bonding and weaker N/O-H...O electrostatic interactions, as compared to two closely related structures.

  19. Structure cristalline de [(CH 3) 3CNH 3] 2SnCl 6 · 2H 2O

    NASA Astrophysics Data System (ADS)

    Ghozlen, M. H. Ben; Daoud, A.; Pabst, Inge

    1991-07-01

    La structure cristalline de [(CH 3) 3CNH 3] 2SnCl 6 · 2H 2O, syste`me orthorhombique, groupe d'espace Pcab avec a = 10.9074(8)Å, b = 10.1322(7)Å, c = 19.148(2)Å, Dcalc = 1.56g/cm 3 et Z = 4 aétérésoluee par les méthodes de Patterson et Fourier utilisant 1290 réflexions mesuréesa`la température ambiante. Les facteurs de reliabilitéobtenus sont R F = 0.036 et R WF = 0.039. La structure est du type antifluorine, les couches d'octae`dres SnCl 2-6 engendrent des trous tétraédriques dans lesquels se situent H 2O et (CH 3) 3CNH +3. Les deux dernie`res entités sont quasiment isolées et reliéesa`SnCl 2-6 par des liaisons hydroge`nes du type N sbnd H ... Cl et O sbnd H ... Cl caractérisées respectivement par les distances N sbnd Cl ˜3.6Ået O sbnd Cl ˜3.4Å.

  20. 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!!!

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

    NASA Astrophysics Data System (ADS)

    Lyons, M.; Siegel, E.

    2010-03-01

    ``Water water everywhere; ne'er a drop to drink''[Coleridg(1798)]; now:``Hydrogen hydrogen everywhere;STILL ne'er a drop to drink'': ONLY H2 can be ``FLYING-WATER''/``chemical-rain-in-pipelines''/ ``Hindenberg-effect (H2-UP;H2O-DOWN): atomic-weights ratio: O/H2O=[16]/[18]˜90%; O already in air uphill; NO H2O pumping need! In water-starved glacial-melting world, rescue ONLY by Siegel[3rd Intl.Conf.Alt.Energy,Hemisphere/Springer(1980)- vol.5/ p.459]Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating- system. Rosenfeld[Sci.315,1396(3/9/2007)]-Biello[Sci.Am.(3/9/ 2007)]crucial geomorphology which ONLY maximal-buoyancy light- est-element H2 can exploit, to again make ``Mountains into Fount- ains": Siegel ``terra-forming''(and ocean-rebasificaton!!!) long pre-``Holdren''-``Ciccerine" ``geo-enginering'', only via Siegel proprietary magnetic-hydrogen-valve permits H2 flow in already in-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Sci.300,1740(03)]global-pandemics (cancers/blindness/famine)dire-warning about H2-(ALONE)economy CATASTROPHIC H2 ozone-layer destruction sobering cavat to dangerous H2-automotion-economy panacea hype!

  2. 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.

  3. Dynamics of gas-driven eruptions: Experimental simulations using CO2-H2O-polymer system

    NASA Astrophysics Data System (ADS)

    Zhang, Youxue; Sturtevant, B.; Stolper, E. M.

    1997-02-01

    We report exploratory experiments simulating gas-driven eruptions using the CO2-H2O system at room temperature as an analog of natural eruptive systems. The experimental apparatus consists of a test cell and a large tank. Initially, up to 1.0 wt% of CO2 is dissolved in liquid water under a pressure of up to 735 kPa in the test cell. The experiment is initiated by suddenly reducing the pressure of the test cell to a typical tank pressure of 10 kPa. The following are the main results: (1) The style of the process depends on the decompression ratio. There is a threshold decompression ratio above which rapid eruption occurs. (2) During rapid eruption, there is always fragmentation at the liquid-vapor interface. Fragmentation may also occur in the flow interior. (3) Initially, the top of the erupting column ascends at a constant acceleration (instead of constant velocity). (4) Average bubble radius grows as t2/3. (5) When viscosity is 20 times that of pure water or greater, a static foam may be stable after expansion to 97% vesicularity. The experiments provide several insights into natural gas-driven eruptions, including (1) the interplay between bubble growth and ascent of the erupting column must be considered for realistic modeling of bubble growth during gas-driven eruptions, (2) buoyant rise of the bubbly magma is not necessary during an explosive volcanic eruption, and (3) CO2-driven limnic eruptions can be explosive. The violence increases with the initial CO2 content dissolved in water.

  4. 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.

  5. 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)

  6. Preparation of poly(acrylic)/SiO2/EuL3 x 2H2O, hybrid thin films from monodispersed colloidal silica.

    PubMed

    Chien, Wen-Chen; Yu, Yang-Yen; Chen, Shih-Yu; Yang, Chang-Chung

    2010-08-01

    In this study, poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films were prepared from various acrylic monomers (MMA and EDMA/TMPTA), lanthanide metal complexes (EuL3 x 2H2O, L = pyridine carboxylic acid), and monodispersed colloidal silica with a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA). It is a combination of the sol-gel reaction, thermal polymerization, and spin coating. The silica content in the hybrid thin films is fixed at 20 wt%, and the EuL3 x 2H2O content is varied from 0.01 g to 0.07 g. FTIR and EA analysis confirms the chemical structure of the prepared EuL3 x 2H2O and poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films. UV-Vis spectra and n&k analysis shows that the hybrid thin film has good transparency in visible light. The refractive index of hybrid thin films can be effectively controlled through the EuL3 x 2H2O content. The PL spectra shows that the strongest emission peak occurs at 615 nm and the emission intensity increases to the peak maximum at an EuL3 x 2H2O content of 0.05 g. Both TGA and PL analysis show that the prepared hybrid thin films from the crosslinked acrylic polymer moiety have much better film uniformity, thermal stability, and fluorescence properties. The TEM diagram shows that the MSMA/SiO2/EuL3 x 2H2O particles with a size 15-20 nm are well dispersed in the reaction solution. The SEM diagram shows that the particle distribution in the prepared hybrid thin films is uniform and no phase separation is observed. Finally, AFM analysis indicates that the prepared hybrid thin films have an excellent surface planarity.

  7. Theoretical studies of UO2(H2O)n2+,NpO2(H2O)n+, and PuO2(H2O)n2+ complexes (n=4-6) in aqueous solution and gas phase

    NASA Astrophysics Data System (ADS)

    Cao, Zhiji; Balasubramanian, K.

    2005-09-01

    Extensive ab initio calculations both in gas phase and solution have been carried out to study the equilibrium structure, vibrational frequencies, and bonding characteristics of various actinyl (UO22+,NpO2+, and PuO22+) and their hydrated forms, AnO2(H2O)nz + (n =4, 5, and 6). Bulk solvent effects were studied using a continuum method. The geometries were fully optimized at the coupled-cluster singles + doubles (CCSD), density-functional theory (DFT), and Møller-Plesset (MP2) level of theories. In addition vibrational frequencies have been obtained at the CCSD as well as MP2/DFT levels. The results show that both the short-range and long-range solvent effects are important. The combined discrete-continuum model, in which the ionic solute and the solvent molecules in the first and second solvation shells are treated quantum mechanically while the solvent is simulated by a continuum model, can predict accurately the bonding characteristics. Moreover, our values of solvation free energies suggest that five- and six-coordinations are equally preferred for UO22+, and five-coordinated species are preferred for NpO2+ and PuO22+. On the basis of combined quantum-chemical and continuum treatments of the hydrated complexes, we are able to determine the optimal cavity radii for the solvation models. The coupled-cluster computations with large basis sets were employed for the vibrational spectra and equilibrium geometries both of which compare quite favorably with experiment. Our most accurate computations reveal that both five- and six-coordination complexes are important for these species.

  8. 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.

  9. Detonation re-initiation in a concentric tube arrangement for C_2 H_2 /O_2 /Ar mixtures

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Lee, J. H. S.; Weng, C.

    2016-11-01

    Re-initiation of detonation in a concentric tube arrangement where a detonation exiting from a small diameter inner tube to a large diameter outer tube has been investigated. The outer tube diameter D is 50.8 mm and inner tube diameters d are 38, 25.4, and 12.7 mm giving diameter ratios D/d=1.34 , 2, and 4. Stoichiometric C_2 H_2 -O_2 mixtures with argon dilution of 0, 25, 50, and 70% are used in the present study. Velocity measurements are made using photodiodes, and smoked foils downstream of the exit of the inner tube are also used to record the re-initiation process. Upon exit from the inner tube, the detonation suffers an abrupt decrease in velocity and at critical conditions, the velocity downstream of the exit is of the order of 50% of the Chapman-Jouguet velocity. It is found that re-initiation generally occurs within 10 tube diameters downstream of the exit. If re-initiation is not successful, the detonation continues to propagate at a low velocity for distances of the order of 30 tube diameters without any indication of flame acceleration of deflagration-to-detonation transition (DDT). Thus, the re-initiation process is clearly defined and distinct from the usual DDT in a smooth tube. The critical d/λ value ratio in the concentric tube is significantly lower than the usual unconfined case of d/λ =13 where λ is the detonation cell size. Thus, it is a result of re-initiation at the Mach stem of the reflected shock from the wall of the outer concentric tube. If re-initiation is not successful upon the first reflection, then subsequent multiple reflections at the tube axis and wall of the outer tube can also result in re-initiation. However, this is only observed for undiluted mixtures. For high-argon-diluted mixtures, re-initiation only occurs at the Mach stem of the first reflection.

  10. 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.

  11. Phase equilibria in the system CO 2-H 2O I: New equilibrium relations at low temperatures

    NASA Astrophysics Data System (ADS)

    Longhi, John

    2005-02-01

    Graphical analysis of free-energy relationships involving binary quadruple points and their associated univariant equilibria in the system CO 2-H 2O suggests the presence of at least 2 previously unrecognized quadruple points and a degenerate binary invariant point involving an azeotrope between CO 2-rich gas and liquid. Thermodynamic data extracted from the equilibrium involving clathrate (hydrate), gas, and ice (H = G+I) are employed along with published data to calculate the P-T range of the 3-ice equilibrium curve, S+I = H, where S is solid CO 2. This equilibrium curve intersects the H = G+I curve approximately where the latter curve intersects the S+H = G curve, thus confirming the existence of one of the inferred quadruple points involving the phases S, G, H, and I. Recognition of some binary equilibria probably have been hampered by extremely low mutual solubilities of CO 2 and H 2O in the fluids phases which, for example, render the S+H = G virtually indistinguishable from the CO 2-sublimation curve. To make the published portion of the L(liquid CO 2)-G-H equilibrium "connect" with the other new quadruple point involving S, L, G, and H, it is necessary to change the sense of the equilibrium from L = G+H at higher pressures to L+H = G at lower pressures by positing a L = G azeotrope at very low concentrations of H 2O. At the low-pressure origin of the azeotrope, which is only a few bars above the CO 2-triple point, the azeotrope curve intersects the 3-phase curve tangentially, creating a degenerate invariant point at which the 3-phase equilibrium changes from L+H = G at lower pressures to L = G+H at higher pressures. The azeotrope curve is offset at slightly lower temperature from the L = G+H curve until the 3-phase equilibrium terminates at the quadruple point involving G, L, H, and W (water). With further increase in pressure the azeotrope curve tracks the L = G+W equilibrium and apparently terminates at a critical end point in close proximity to critical

  12. Static magnetic properties and relaxation of the insulating spin glass Co1-xMnxCl2.H2O

    NASA Astrophysics Data System (ADS)

    Defotis, G. C.; Coker, G. S.; Jones, J. W.; Branch, C. S.; King, H. A.; Bergman, J. S.; Lee, S.; Goodey, J. R.

    1998-11-01

    The magnetic properties of Co1-xMnxCl2.H2O are examined by dc magnetization and susceptibility measurements, for x=0.05, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, and 0.95 between 1.8 and 300 K. The pure components are a quasi-one-dimensional Heisenberg antiferromagnet (Mn) and an antiferromagnetic reentrant spin glass (Co) with some low-dimensional character. The Curie and Weiss constants, in χM=C/(T-θ), show regular composition dependence, with θ(x) varying nonlinearly from positive to negative values as x increases. Antiferromagnetic maxima often occur, and transition temperatures are estimated for most mixtures. The T-x diagram shows two descending boundaries from either composition extreme; any transition temperatures for x=0.5-0.8 are lower than we can measure. Magnetization isotherms evolve with composition, and associated hysteretic effects weaken with increasing x. The nonlinear susceptibility for x=0.30 shows structure, but does not diverge. The thermoremanent magnetization (TRM) is examined in detail for x=0.30, 0.40, and 0.50. Its temperature dependence shows characteristic features, but does not follow any simple form. Systematic variation in the TRM with cooling field and composition is apparent. The time dependence of the TRM is fit using a stretched exponential decay form. Systematic variations in the fit parameters with temperature, cooling field, and composition emerge. For low to moderate temperatures, the TRM is found to scale according to T log10(t/τ0), with τ0~10-12-10-13 s. For x=0.30 and 0.50, strong and weak irreversibility lines are determined. The former conform better to a recent prediction for the short-range three-dimensional Ising spin glass, τg~h0.53, than to the DeAlmeida-Thouless mean-field form τg~h2/3 best-fit exponents are slightly less than 0.53. For the weak irreversibility lines, the dependence of τg on field is much weaker than the Gabay-Toulouse form τg~h2. The presence of strong random anisotropy is a

  13. Improvement in surface hydrophilicity and resistance to deformation of natural leather through O2/H2O low-temperature plasma treatment

    NASA Astrophysics Data System (ADS)

    You, Xuewei; Gou, Li; Tong, Xingye

    2016-01-01

    The natural leather was modified through O2/H2O low-temperature plasma treatment. Surface morphology was characterized by scanning electron microscopy (SEM) and the results showed that the pores on the leather surface became deeper and larger with enhanced permeability of water and vapor. XPS and FTIR-ATR was performed to determine the chemical composition of natural leather surface. Oxygen-containing groups were successfully grafted onto the surface of natural leather and oxygen content increased with longer treatment time. After O2/H2O plasma treatment, initial water contact angle was about 21° and water contact angles were not beyond 55° after being stored for 3 days. Furthermore, the tensile test indicated that the resistance to deformation had a prominent transform without sacrificing the tensile strength.

  14. 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.

  15. Nqrs Data for C3H12INO7 [C3H7NO2·HIO3·2(H2O)] (Subst. No. 0646)

    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 C3H12INO7 [C3H7NO2·HIO3·2(H2O)] (Subst. No. 0646)

  16. 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)

  17. Paramagnetic-diamagnetic phase transition accompanied by coordination bond formation-dissociation in the dithiolate complex Na[Ni(pdt)2]·2H2O.

    PubMed

    Takaishi, Shinya; Ishihara, Nozomi; Kubo, Kazuya; Katoh, Keiichi; Breedlove, Brian K; Miyasaka, Hitoshi; Yamashita, Masahiro

    2011-07-18

    Bis(2,3-pyrazinedithiolate)nickel complex Na[Ni(pdt)(2)]·2H(2)O formed one-dimensional stacks of the Ni(pdt)(2) units and showed strong antiferromagnetic interactions along the stacking direction. A first-order phase transition between the paramagnetic and diamagnetic states, which was driven by dimerization of the Ni(pdt)(2) units, accompanied by coordination bond formation, was observed.

  18. 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

    2011-09-08

    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.

  19. Kinetics of CO/CO2 and H2/H2O reactions at Ni-based and ceria-based solid-oxide-cell electrodes.

    PubMed

    Graves, Christopher; Chatzichristodoulou, Christodoulos; Mogensen, Mogens B

    2015-01-01

    The solid oxide electrochemical cell (SOC) is an energy conversion technology that can be operated reversibly, to efficiently convert chemical fuels to electricity (fuel cell mode) as well as to store electricity as chemical fuels (electrolysis mode). The SOC fuel-electrode carries out the electrochemical reactions CO2 + 2e(-) ↔ CO + O(2-) and H2O + 2e(-) ↔ H2 + O(2-), for which the electrocatalytic activities of different electrodes differ considerably. The relative activities in CO/CO2 and H2/H2O and the nature of the differences are not well studied, even for the most common fuel-electrode material, a composite of nickel and yttria/scandia stabilized zirconia (Ni-SZ). Ni-SZ is known to be more active for H2/H2O than for CO/CO2 reactions, but the reported relative activity varies widely. Here we compare AC impedance and DC current-overpotential data measured in the two gas environments for several different electrodes comprised of Ni-SZ, Gd-doped CeO2 (CGO), and CGO nanoparticles coating Nb-doped SrTiO3 backbones (CGOn/STN). 2D model and 3D porous electrode geometries are employed to investigate the influence of microstructure, gas diffusion and impurities.Comparing model and porous Ni-SZ electrodes, the ratio of electrode polarization resistance in CO/CO2vs. H2/H2O decreases from 33 to 2. Experiments and modelling suggest that the ratio decreases due to a lower concentration of impurities blocking the three phase boundary and due to the nature of the reaction zone extension into the porous electrode thickness. Besides showing higher activity for H2/H2O reactions than CO/CO2 reactions, the Ni/SZ interface is more active for oxidation than reduction. On the other hand, we find the opposite behaviour in both cases for CGOn/STN model electrodes, reporting for the first time a higher electrocatalytic activity of CGO nanoparticles for CO/CO2 than for H2/H2O reactions in the absence of gas diffusion limitations. We propose that enhanced surface reduction at the

  20. Investigation into the effect on structure of oxoanion doping in Na2M(SO4)2·2H2O

    NASA Astrophysics Data System (ADS)

    Driscoll, L. L.; Kendrick, E.; Wright, A. J.; Slater, P. R.

    2016-10-01

    In this paper an investigation into the effect of transition metal ion and selenate/fluorophosphate doping on the structures of Na2M(SO4)2·2H2O (M=transition metal) materials is reported. In agreement with previous reports, the monoclinic (Kröhnkite) structure is adopted for M=Mn, Fe, Co, Cu, while for the smallest first row divalent transition metal ion, M=Ni, the triclinic (Fairfieldite structure) is adopted. On selenate doping there is a changeover in structure from monoclinic to triclinic for M=Fe, Co, Cu, with the larger Fe2+ system requiring the highest level of selenate to complete the changeover. Thus the results suggest that the relative stability of the two structure types is influenced by the relative size of the transition metal: oxoanion group, with the triclinic structure favoured for small transition metals/large oxoanions. The successful synthesis of fluorophosphate doped samples, Na2M(SO4)2-x(PO3F)x·2H2O was also obtained for M=Fe, Co, Cu, with the results showing a changeover in structure from monoclinic to triclinic for M=Co, Cu for very low levels (x=0.1) of fluorophosphate. In the case of M=Fe, the successful synthesis of fluorophosphates samples was achieved for x≤0.3, although no change in cell symmetry was observed. Rather in this particular case, the X-ray diffraction patterns showed evidence for selective peak broadening, attributed to local disorder as a result of the fluorophosphate group disrupting the H-bonding network. Overall the work highlights how isovalent doping can be exploited to alter the structures of Na2M(SO4)2·2H2O systems.

  1. Ab initio molecular dynamics simulations reveal localization and time evolution dynamics of an excess electron in heterogeneous CO2-H2O systems.

    PubMed

    Liu, Ping; Zhao, Jing; Liu, Jinxiang; Zhang, Meng; Bu, Yuxiang

    2014-01-28

    In view of the important implications of excess electrons (EEs) interacting with CO2-H2O clusters in many fields, using ab initio molecular dynamics simulation technique, we reveal the structures and dynamics of an EE associated with its localization and subsequent time evolution in heterogeneous CO2-H2O mixed media. Our results indicate that although hydration can increase the electron-binding ability of a CO2 molecule, it only plays an assisting role. Instead, it is the bending vibrations that play the major role in localizing the EE. Due to enhanced attraction of CO2, an EE can stably reside in the empty, low-lying π(*) orbital of a CO2 molecule via a localization process arising from its initial binding state. The localization is completed within a few tens of femtoseconds. After EE trapping, the ∠OCO angle of the core CO2 (-) oscillates in the range of 127°∼142°, with an oscillation period of about 48 fs. The corresponding vertical detachment energy of the EE is about 4.0 eV, which indicates extreme stability of such a CO2-bound solvated EE in [CO2(H2O)n](-) systems. Interestingly, hydration occurs not only on the O atoms of the core CO2 (-) through formation of O⋯H-O H-bond(s), but also on the C atom, through formation of a C⋯H-O H-bond. In the latter binding mode, the EE cloud exhibits considerable penetration to the solvent water molecules, and its IR characteristic peak is relatively red-shifted compared with the former. Hydration on the C site can increase the EE distribution at the C atom and thus reduce the C⋯H distance in the C⋯H-O H-bonds, and vice versa. The number of water molecules associated with the CO2 (-) anion in the first hydration shell is about 4∼7. No dimer-core (C2O4 (-)) and core-switching were observed in the double CO2 aqueous media. This work provides molecular dynamics insights into the localization and time evolution dynamics of an EE in heterogeneous CO2-H2O media.

  2. 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

  3. Sequential bond energies and barrier heights for the water loss and charge separation dissociation pathways of Cd2+(H2O)n, n = 3-11

    NASA Astrophysics Data System (ADS)

    Cooper, Theresa E.; Armentrout, P. B.

    2011-03-01

    The bond dissociation energies for losing one water from Cd2+(H2O)n complexes, n = 3-11, are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer coupled with a thermal electrospray ionization source. Kinetic energy dependent cross sections are obtained for n = 4-11 complexes and analyzed to yield 0 K threshold measurements for loss of one, two, and three water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. The threshold measurements are converted from 0 to 298 K values to give the hydration enthalpies and free energies for sequentially losing one water from each complex. Theoretical geometry optimizations and single point energy calculations are performed on reactant and product complexes using several levels of theory and basis sets to obtain thermochemistry for comparison to experiment. The charge separation process, Cd2+(H2O)n → CdOH+(H2O)m + H+(H2O)n-m-1, is also observed for n = 4 and 5 and the competition between this process and water loss is analyzed. Rate-limiting transition states for the charge separation process at n = 3-6 are calculated and compared to experimental threshold measurements resulting in the conclusion that the critical size for this dissociation pathway of hydrated cadmium is ncrit = 4.

  4. The determination of deep temperatures by means of the CO-CO2-H2-H2O geothermometer: an example using fumaroles in the Campi Flegrei, Italy

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Sabroux, J. C.

    1987-02-01

    Chromatographic analyses of fumarolic gases, collected in sampling bottles containing an alkaline solution, have been carried out using a thermal conductivity detector and a flame ionization detector, after catalytic conversion of CO and CH4. The latter method enables the concentration of carbon monoxide to be measured with sufficient accuracy for use in a CO-CO2-H2-H2O geothermometer. Application of this geothermometer to fumaroles in the crater of Solfatara in the Campi Flegrei, Italy, indicates that they are fed from a steam reservoir at 250±15 °C and at 10-36±2atm of oxygen. On the other hand, the CH4-CO2-H2-H2O geothermobarometer seems to re-equilibrate at superficial temperatures and cannot be used for infering thermodynamic conditions at depth. Regular sampling of these fumaroles together with a geothermometric interpretation of the gas analyses provides a means of monitoring, with comparative accuracy, the chemical and thermal evolution of the hydrothermal reservoir below the Solfatara crater. Such monitoring would probably detect an increase in temperature at depth and the injection of magmatic gas into the reservoir.

  5. The generation of HCl in the system CaCl2-H2O: Vapor-liquid relations from 380-500°C

    USGS Publications Warehouse

    Bischoff, James L.; Rosenbauer, Robert J.; Fournier, Robert O.

    1996-01-01

    We determined vapor-liquid relations (P-T-x) and derived critical parameters for the system CaCl2-H2O from 380-500??C. Results show that the two-phase region of this system is extremely large and occupies a significant portion of the P-T space to which circulation of fluids in the Earth's crust is constrained. Results also show the system generates significant amounts of HCl (as much as 0.1 mol/kg) in the vapor phase buffered by the liquid at surprisingly high pressures (???230 bars at 380??C, <580 bars at 500??C), presumably by hydrolysis of CaCl2: CaCl2 + 2H2O = Ca(OH)2 + 2HCl. We interpret the abundance of HCl in the vapor as due to its preference for the vapor phase, and by the preference of Ca(OH)2 for either the liquid phase or solid. The recent recognition of the abundance of CaCl2 in deep brines of the Earth's crust and their hydrothermal mobilization makes the hydrolysis of CaCl2 geologically important. The boiling of Ca-rich brines produces abundant HCl buffered by the presence of the liquid at moderate pressures. The resultant Ca(OH)2 generated by this process reacts with silicates to form a variety of alteration products, such as epidote, whereas the vapor produces acid-alteration of rocks through which it ascends.

  6. Antioxidants prevented oxidative injury of SR induced by Fe2+/H2O2/ascorbate system but failed to prevent Ca2+-ATPase activity decrease.

    PubMed

    Horáková, Lubica; Strosová, Miriam; Skuciová, Mária

    2005-01-01

    Dysfunction of sarcoplasmic reticulum (SR) Ca2+-ATPase induced by oxidative stress may be a contributing factor to the development of serious age related diseases. Incubation of sarcoplasmic reticulum (SR) vesicles of rabbit skeletal muscles with Fe2+/H2O2/ascorbate decreased the SH group content of SR approximately to 35% and Ca2+-ATPase activity to 50% of control not oxidized sample. Protein carbonyls increased twofold, lipid peroxidation was also significantly elevated. The antioxidant effects of trolox, the pyridoindole derivative stobadine and of the standardized extracts from bark of Pinus Pinaster PycnogenolR (Pyc) and from leaves of Ginkgo biloba (EGb 761) were studied on oxidatively injured SR. All antioxidants exerted preventive effects against the oxidized lipids and protein SH groups of SR vesicles. Trolox and stobadine did not influence protein carbonyl formation, while flavonoid extracts prevented carbonyl generation, probably by binding to protein. The preventive effects of the antioxidants studied on lipids and protein SH groups were however not associated with protection of Ca2+-ATPase activity. Stobadine and trolox exerted no effect on enzyme activity, Pyc and EGb 761 enhanced the inhibitory effect of Ca2+-ATPase activity in oxidatively injured SR. Concluding, under the conditions of oxidative stress induced by Fe2+/H2O2/ascorbate against SR of rabbit skeletal muscle, the agents studied demonstrated antioxidant effects yet failed to protect Ca2+-ATPase activity.

  7. 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.

  8. Influence of Different Surfactants on Morphology of Single Crystal Ce2O(CO3)2.H2O and Formation Mechanism

    NASA Astrophysics Data System (ADS)

    Mei, Yan; Han, Ye-bin; Nie, Zuo-ren

    2006-06-01

    Three kinds of ultra-fine Ce2O(CO3)2.H2O powders with different morphologies were prepared by adding CTAB, PEG19000 and OP-10 to a solution of Ce2O(NO3)3.6H2O and urea according to the principle and the characteristics of the homogeneous precipitation method. The products were characterized by TEM and XRD. The results showed that the precursor was a single crystal, and that different surfactants had different influences on the morphology of the products. The cationic surfactant CTAB had little effect on crystal morphology merely reducing its size. Nonionic surfactants PEG19000 and OP-10 are both able to change the crystal morphology to a much greater extent. Adding PEG19000 produces an array of rod-like particles with ordered formation and uniform dimension. Meanwhile, in the system of OP-10, a sort of flower-like pattern with a dispersed center can be prepared. The formations of ultra-fine Ce2O(CO3)2.H2O powders with different morphologies occured because of the mechanism of formation and grain growth.

  9. Post-treatment of palm oil mill effluent (POME) using combined persulphate with hydrogen peroxide (S2O8(2-)/H2O2) oxidation.

    PubMed

    Lin, Chia Ken; Bashir, Mohammed J K; Abu Amr, Salem S; Sim, Lan Ching

    2016-12-01

    The aim of the current study is to evaluate the effectiveness of combined persulphate with hydrogen peroxide (S2O8(2-)/H2O2) oxidation as a post-treatment of biologically treated palm oil mill effluent (POME) for the first time in the literature. The removal efficiencies of chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), and suspended solids (SS) were 36.8%, 47.6%, and 90.6%, respectively, by S2O8(2-) oxidation alone under certain operation conditions (i.e., S2O8(2-) = 0.82 g, pH 11, and contact time 20 min). Nevertheless, the combined process (S2O8(2-)/H2O2) achieved 75.8% and 87.1% removals of NH3-N and SS, respectively, under 2.45/1.63 g/g H2O2/S2O8(2-), pH 11, and 20 min oxidation. Moreover, 56.9% of COD was removed at pH 8.4.

  10. Malonate-containing manganese(III) complexes: synthesis, crystal structure, and magnetic properties of AsPh4[Mn(mal)2(H2O)2].

    PubMed

    Delgado, Fernando S; Kerbellec, Nicolas; Ruiz-Pérez, Catalina; Cano, Joan; Lloret, Francesc; Julve, Miguel

    2006-02-06

    The novel manganese(III) complexes PPh4[Mn(mal)2(H2O)2] (1) and AsPh4[Mn(mal)2(H2O)2] (2) (PPh4+ = tetraphenylphosphonium cation, AsPh4+ = tetraphenylarsonium cation, and H2mal = malonic acid) have been prepared, and the structure of 2 was determined by X-ray diffraction analysis. 2 is a mononuclear complex whose structure is made up of trans-diaquabis(malonato)manganate(III) units and tetraphenylarsonium cations. Two crystallographically independent manganese(III) ions (Mn(1) and Mn(2)) occur in 2 that exhibit elongated octahedral surroundings with four oxygen atoms from two bidentate malonate groups in equatorial positions (Mn(1)-O = 1.923(6) and 1.9328(6) A and Mn(2)-O = 1.894(6) and 1.925(6) A) and two trans-coordinated water molecules in the axial sites (Mn(1)-Ow = 2.245(6) A and Mn(2)-Ow = 2.268(6) A). The [Mn(mal)2(H2O)2]- units are linked through hydrogen bonds involving the free malonate-oxygen atoms and the coordinated water molecules to yield a quasi-square-type anionic layer growing in the ab plane. The shortest intralayer metal-metal separations are 7.1557(7) and 7.1526(7) A (through the edges of the square). The anionic sheets are separated from each other by layers of AsPh4+ where sextuple- and double-phenyl embraces occur. The magnetic behavior of 1 and 2 in the temperature range 1.9-290 K reveals the occurrence of weak intralayer ferromagnetic interactions (J = +0.081(1) (1) and +0.072(2) cm(-1) (2)). These values are compared to those of the weak antiferromagnetic coupling [J = -0.19(1) cm(-1)], which is observed in the chain compound K2[Mn(mal)2(MeOH)2][Mn(mal)2] (3), where the exchange pathway involves the carboxyate-malonate bridge in the anti-syn conformation. The structure of 3 was reported elsewhere. Theoretical calculations on fragment models of 2 and 3 were performed to analyze and substantiate both the nature and magnitude of the magnetic couplings observed.

  11. Synthesis, characterization, single crystal X-ray structure, EPR and theoretical studies of a new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O and its structural comparison with related [Cu(en)2(H2O)2](pnb)2

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Sharma, Raj Pal; Venugopalan, Paloth; Witwicki, Maciej; Ferretti, Valeria

    2016-11-01

    A new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O (1) (where pnb = p-nitrobenzoate), in which the tridentate ligand diethylenetriamine (dien) shows an unusual coordination behavior acting as a bidentate ligand when present in its monoprotonated form (Hdien+) has been synthesized by the reaction of copper(II) p-nitrobenzoate and slight excess of dien in methanol-water mixture (4:1v/v). Re-crystallization of the violet precipitated product from hot water gave single crystals suitable for X-ray diffraction studies. The newly synthesized compound 1 has been characterized by spectroscopic techniques (UV-Vis, FT-IR, EPR), and theoretical methods (DFT and MRCI/SORCI). Single crystal X-ray structure determination revealed the existence of the cationic species [Cu(Hdien)2(H2O)2]4+, four p-nitrobenzoate as counter anions and four water molecules are present as solvent of crystallization. Packing analyses of title compound as well as of the structurally similar [Cu(en)2(H2O)2](pnb)2,2 has shown similarities in the crystalline architecture that both hybrid inorganic-organic compounds is stabilized by various non-covalent interactions such as N-H⋯O, C-H⋯O, O-H⋯O etc.

  12. Calculation of the solubility diagrams in the system Ca(OH) 2-H 3PO 4-KOH-HNO 3-CO 2-H 2O

    NASA Astrophysics Data System (ADS)

    Vereecke, Guy; Lemaître, Jacques

    1990-09-01

    A computer program has been developed for calculating the solubility isotherms of sparingly soluble calcium phosphates (including octacalcium phosphate and β-tricalcium phosphate) and calcite in the system Ca(OH) 2-H 3PO 4-KOH-HNO 3-CO 2-H 2O. It allows the influence of such parameters as temperature, pH, partial CO 2 pressure and ionic strength to be investigated. The calculation process takes into account the effects of ion-pair formation and ionic strength. Selected solubility isotherms are presented and compared to literature data. The influence of temperature, Ca/P ratio, ionic strength and CO 2 pressure on the stability isotherms of hydroxyapatite and dicalcium phosphate are discussed in detail.

  13. Single-crystalline hyperbranched nanostructure of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O for highly selective capture of phosphopeptides.

    PubMed

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

    2014-01-17

    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.

  14. Magnetic susceptibility and Mössbauer studies of [FeX3](ClO4)2.H2O with X = bpz, bpy, phen or tpy

    NASA Astrophysics Data System (ADS)

    Ho, J. C.; Hamdeh, H. H.; Kirgan, R.; Rillema, D. P.

    2008-03-01

    Magnetic studies have been made on several tris-chelated iron complex compounds [FeX3](ClO4)2.H2O with aromatic nitrogen heterocycle ligands X = bpz (2,2'-bipyrazine), bpy (2,2'-bipyridine), phen (1,10-phenanthroline) or tpy (2,2':6,2''-terpyridine). SQUID data (2-300 K and 0.01-1 T) yielded small effective magnetic moments, which are characteristic of low-spin Fe(II), in agreement with the isomer shift and quadrupole splitting values from Mössbauer measurements (4-300 K, 0-5 T). Meanwhile, apart from the expected diamagnetism, a positive term of temperature-independent paramagnetic susceptibility prevails in most cases.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. Double Salts Obtained from Me+X-Cu X2-H 2O Systems ( Me+ = K +, NH +4, rb +, cs +; X- = cl -, br -)

    NASA Astrophysics Data System (ADS)

    Tepavitcharova, St.; Balarew, Chr.; Trendafilova, St.

    1995-02-01

    The solubility diagrams of the Me+ Br-CuBr2-H2O (Me+ = K+, NH+4, Rb+, Cs+) systems are studied. The results obtained are compared with literature data on the corresponding chloride systems in order to estimate the effect of the halide ion (Br- or Cl-) on the solubility diagrams and on the compositions of the double salts formed in these systems. The differences in composition and structure of the double salts are explained by the metal-ligand interactions on the basis of Pearson's concept of hard and soft Lewis acids and bases, as well as by crystal chemistry considerations for the most probable spacial situation of the building elements in the crystal structure.

  20. A potential energy surface for the process H2 + H2O yielding H + H + H2O - Ab initio calculations and analytical representation

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Walch, Stephen P.; Taylor, Peter R.

    1991-01-01

    Extensive ab initio calculations on the ground state potential energy surface of H2 + H2O were performed using a large contracted Gaussian basis set and a high level of correlation treatment. An analytical representation of the potential energy surface was then obtained which reproduces the calculated energies with an overall root-mean-square error of only 0.64 mEh. The analytic representation explicitly includes all nine internal degrees of freedom and is also well behaved as the H2 dissociates; it thus can be used to study collision-induced dissociation or recombination of H2. The strategy used to minimize the number of energy calculations is discussed, as well as other advantages of the present method for determining the analytical representation.

  1. 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

  2. Observation of the pi...H hydrogen-bonded ternary complex, (C(2)H(4))(2)H(2)O, using matrix isolation infrared spectroscopy.

    PubMed

    Thompson, Matthew G K; Lewars, Errol G; Parnis, J Mark

    2005-10-27

    FTIR absorption spectra of water-containing ethene:Ar matrices, with compositions of ethene up to 1:10 ethene:Ar, have been recorded. Systematically increasing the concentration of ethene reveals features in the spectra consistent with the known 1:1 ethene:water complex, which subsequently disappear on further increase in ethene concentration. At high concentrations of ethene, new features are observed at 3669 and 3585 cm(-1), which are red-shifted with respect to matrix-isolated nu(3) and nu(1) O-H stretching modes of water and the 1:1 ethene:water complex. These shifts are consistent with a pi...H interaction of a 2:1 ethene:water complex of the form (C(2)H(4)...H-O-H...C(2)H(4)). The analogous (C(2)D(4))(2)H(2)O complex shows little shifting from positions associated with (C(2)H(4))(2)H(2)O, while the (C(2)H(4))(2)D(2)O isotopomer shows large shifts to 2722.3 and 2617.2 cm(-1), having identical nu(3)(H(2)O)/nu(3)(D(2)O) and nu(1)(H(2)O)/nu(1)(D(2)O) values when compared with monomeric water isotopomers. Features at 3626.1 and 2666.2 cm(-1) are also observed and are attributed to (C(2)H(4))(2)HDO. DFT calculations at the B3LYP/6-311+G(d,p) level for each isotopomer are presented, and the predicted vibrational frequencies are directly compared with experimental values. The interaction energy for the formation of the 2:1 ethene:water complex from the 1:1 ethene:water complex is also presented.

  3. Synthesis and structure of dimeric anthracene-9-carboxylato bridged dinuclear erbium(III) complex, [Er(2)(9-AC)(6)(DMF)(2)(H(2)O)(2)].

    PubMed

    Kusrini, Eny; Adnan, Rohana; Saleh, Muhammad I; Yan, Lim-Kong; Fun, Hoong-Kun

    2009-05-01

    We study the influence of the bulky aromatic rings, e.g. anthracence-9-carboxylic acid (9-ACA) with a large conjugated pi-system on the structure and spectroscopic properties of [Er(2)(9-AC)(6)(DMF)(2)(H(2)O)(2)] complex where 9-AC=anthracence-9-carboxylato and DMF=N,N'-dimethylformamide. The complex has been prepared from the erbium chloride and 9-ACA in the mixture of H(2)O:DMF solution (4:1, v/v) followed by pH adjustment to 6. The complex is crystallized in a monoclinic system with space group P2(1)/n. The two Er(III) ions are double bridged by the deprotonated carboxyl groups of two 9-AC anions (O1 and O1A), forming an eight-coordination number. The chelating bidentate (O,O), chelating-bridging tridentate (O,O,O') and monodentate of 9-AC anions are observed in the dinuclear [Er(2)(9-AC)(6)(DMF)(2)(H(2)O)(2)] complex. The Er-Er distance is 4.015A in the dimeric unit. Intramolecular O-Hcdots, three dots, centeredO and C-Hcdots, three dots, centeredO hydrogen bonds as well as numerous of intermolecular C-Hcdots, three dots, centeredpi interactions between the anthracene rings by edge-to-face interactions linked the dinuclear dimeric units into two-dimensional supramolecular network in a propeller-arrangement. Electronic absorption spectra of the Er(III) complex and its salt were measured. The emission spectrum of the complex is composed of a broad band due to the emission of intraligand pi*-->pi transition from the 9-AC anions and a shoulder peak originating from the 4f-4f emission transition of the Er(III) ions. The complex has a high thermal stability which can be attributed to the effectively increase the rigidity of the 9-AC anions.

  4. 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.

  5. Iron weathering products in a CO 2 + (H 2O or H 2O 2) atmosphere: Implications for weathering processes on the surface of Mars

    NASA Astrophysics Data System (ADS)

    Chevrier, V.; Mathé, P.-E.; Rochette, P.; Grauby, O.; Bourrié, G.; Trolard, F.

    2006-08-01

    Various iron-bearing primary phases and rocks have been weathered experimentally to simulate possible present and past weathering processes occurring on Mars. We used magnetite, monoclinic and hexagonal pyrrhotites, and metallic iron as it is suggested that meteoritic input to the martian surface may account for an important source of reduced iron. The phases were weathered in two different atmospheres: one composed of CO 2 + H 2O, to model the present and primary martian atmosphere, and a CO 2 + H 2O + H 2O 2 atmosphere to simulate the effect of strong oxidizing agents. Experiments were conducted at room temperature and a pressure of 0.75 atm. Magnetite is the only stable phase in the experiments and is thus likely to be released on the surface of Mars from primary rocks during weathering processes. Siderite, elemental sulfur, ferrous sulfates and ferric (oxy)hydroxides (goethite and lepidocrocite) are the main products in a water-bearing atmosphere, depending on the substrate. In the peroxide atmosphere, weathering products are dominated by ferric sulfates and goethite. A kinetic model was then developed for iron weathering in a water atmosphere, using the shrinking core model (SCM). This model includes competition between chemical reaction and diffusion of reactants through porous layers of secondary products. The results indicate that for short time scales, the mechanism is dominated by a chemical reaction with second order kinetics ( k = 7.75 × 10 -5 g -1/h), whereas for longer time scales, the mechanism is diffusion-controlled (De A = 2.71 × 10 -10 m 2/h). The results indicate that a primary CO 2- and H 2O-rich atmosphere should favour sulfur, ferrous phases such as siderite or Fe 2+-sulfates, associated with ferric (oxy)hydroxides (goethite and lepidocrocite). Further evolution to more oxidizing conditions may have forced these precursors to evolve into ferric sulfates and goethite/hematite.

  6. Threshold collision-induced dissociation of Sr2+(H2O)x complexes (x=1-6): An experimental and theoretical investigation of the complete inner shell hydration energies of Sr2+

    NASA Astrophysics Data System (ADS)

    Carl, D. R.; Chatterjee, B. K.; Armentrout, P. B.

    2010-01-01

    The sequential bond energies of Sr2+(H2O)x complexes, where x =1-6, are determined by threshold collision-induced dissociation using a guided ion beam tandem mass spectrometer equipped with an electrospray ionization source. The electrospray source produces an initial distribution of Sr2+(H2O)x complexes, where x =6-9. Smaller Sr2+(H2O)x complexes, where x =1-5, are accessed using a recently developed in-source fragmentation technique that takes place in the high pressure region of a rf-only hexapole ion guide. This work constitutes the first experimental study for the complete inner shell of any multiply charged ion. The kinetic energy dependent cross sections are determined over a wide energy range to monitor all possible dissociation products and are modeled to obtain 0 and 298 K binding energies for loss of a single water molecule. These binding energies decrease monotonically for the Sr2+(H2O) complex to Sr2+(H2O)6. Our experimental results agree well with previous literature results obtained by equilibrium and kinetic studies for x =5 and 6. Because there has been limited theory for the hydration of Sr2+, we also present an in-depth theoretical study on the energetics of the Sr2+(H2O)x systems by employing several levels of theory with multiple effective core potentials for Sr and different basis sets for the water molecules.

  7. 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

  8. Millimeter Wave Spectra of the Internal Rotation Excited States of (o)H_2-H_2O and (o)H_2-D_2O

    NASA Astrophysics Data System (ADS)

    Harada, K.; Iwasaki, Y.; Giesen, T.; Tanaka, K.

    2013-06-01

    H_2-H_2O is a weakly bound complex and it has a various states according to the internal rotation for both H_2 and H_2O moieties. In our previous study, we have reported the pure rotational transitions of the (o)H_2 complex in the ground H_2O rotational state, 0_{00}(Σ), for both H_2-H_2O and H_2-D_2O, where (o)H_2 (j_{ H2} =1) is rotating perpendicular to the intermolecular axis to give the projection of j_{ H2} to the axis k_{ H2} to be zero (i.e. Σ state). In the present study, we have observed the rotational transitions for the 0_{00} (Π) states in the millimeter-wave region up to 220 GHz, where the (o)H_2 is rotating around the intermolecular axis to give the projection k_{ H2} to be one (i.e. Π state). The center of mass bond lengths derived from the observed rotational constants for 0_{00} (Π) are longer by 5 % than those for 0_{00} (Σ), while force constants for the intermolecular stretching for 0_{00} (Π) derived from centrifugal distortion constants are smaller by 23 % than those for 0_{00} (Σ), suggesting the Π and Σ substates have quite different structures. The recent theoretical calculation indicates that for 0_{00}(Σ), (o)H_2 is bound to the oxygen site of H_2O, while for the 0_{00} (Π) state, (o)H_2 to the hydrogen site of H_2O, and the 0_{00}(Σ) state is by 14 cm^{-1} more stable than the 0_{00} (Π) state. Observed molecular constants for 0_{00}(Σ) and (Π) are consistent with the structures given by the theoretical calculation. We also observed the rotational spectrum in the 1_{01} (Σ) and (Π) states, where Σ and Π correspond to the rotation of H_2O perpendicular and parallel to the intermolecular axis and (o)H_2 is calculated to be bound to the oxygen site of H_2O. The energy difference between the 1_{01} (Σ) and (Π) states will be discussed due to the Criolis interaction between these substates. C. J. Whitham, K. Tanaka, and K. Harada, The 56th OSU Symposium, RD08 (2001). Ad. van der Avoid and D. J. Nesbit, J. Chem. Phys

  9. 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

  10. Hydrous melting and partitioning in and above the mantle transition zone: Insights from water-rich MgO-SiO2-H2O experiments

    NASA Astrophysics Data System (ADS)

    Myhill, R.; Frost, D. J.; Novella, D.

    2017-03-01

    Hydrous melting at high pressures affects the physical properties, dynamics and chemical differentiation of the Earth. However, probing the compositions of hydrous melts at the conditions of the deeper mantle such as the transition zone has traditionally been challenging. In this study, we conducted high pressure multianvil experiments at 13 GPa between 1200 and 1900 °C to investigate the liquidus in the system MgO-SiO2-H2O. Water-rich starting compositions were created using platinic acid (H2Pt(OH)6) as a novel water source. As MgO:SiO2 ratios decrease, the T -XH2O liquidus curve develops an increasingly pronounced concave-up topology. The melting point reduction of enstatite and stishovite at low water contents exceeds that predicted by simple ideal models of hydrogen speciation. We discuss the implications of these results with respect to the behaviour of melts in the deep upper mantle and transition zone, and present new models describing the partitioning of water between the olivine polymorphs and associated hydrous melts.

  11. 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.

  12. A novel hydrogen bonded bimetallic supramolecular coordination polymer {[SnMe3(bpe)][Ag(CN)2] · 2H2O} as anticancer drug.

    PubMed

    Etaiw, Safaa El-Din H; Sultan, Ahmed S; Badr El-Din, Ahmed S

    2011-11-01

    The reaction of Me(3)SnCl, K(3)[Ag(CN)(4)] and 1,2-bis(4-pyridyl)ethane (bpe) in water/CH(3)CN solution at room temperature affords the novel bimetallic supramolecular coordination polymer (SCP) {[SnMe(3)(bpe)] [Ag(CN)2] · 2H(2)O}(n), 1. The structure of 1 consists of cationic {-Sn(Me(3))-bpe-}(+) chains that are neutralized by [Ag(CN)(2)](-) anions. The dicyanoargentate(I) anions present discrete uncoordinated fragments between the cationic chains. The water molecules bind the cationic chains and the anions forming 3D-supramolecular structure through hydrogen bonds. 1 exhibits strong fluorescence in the solid state at room temperature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the in vitro antitumor effects of the SCP 1 on human breast cancer cell line, T-47D. Cell cycle analysis revealed that the SCP 1 induced apoptosis in T-47D breast cancer cell line. Moreover, in vivo, the SCP 1 showed tumor growth inhibition in rat model that developed mammary carcinoma by 44.8% compared to the vehicle treated control. Thus, the SCP 1 exhibits specific in vivo and in vitro antitumor effects.

  13. 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.

  14. The first study of antiferromagnetic eosphorite-childrenite series (Mn1-xFex)AlP(OH)2H2O (x=0.5)

    NASA Astrophysics Data System (ADS)

    Behal, D.; Röska, B.; Park, S.-H.; Pedersen, B.; Benka, G.; Pfleiderer, Ch.; Wakabayashi, Y.; Kimura, T.

    2017-04-01

    This study presents for the first time the antiferromagnetic structure of the eosphorite-childrenite series (Mn1-xFex)AlPO4(OH)2H2O (x=0.5), based on neutron single crystal diffraction at 3 K in combination with group theoretical representation analysis. The new magnetic structure is described in the magnetic space group PCmnb, maintaining the atomistic unit cell size (a×b×c) with a 6.9 Å, b 10.4 Å, c 13.4 Å. Mn-rich and Fe-rich zones within solid solution crystals are expanded up to several hundred micrometers, as seen in electron microprobe and polarisation microscopy. Magnetic susceptibility and specific heat measurements on two different eosphorite-childrenite crystals show the magnetic transition temperature between 6.5 K and 6.8 K as the Mn2+/Fe2+ ratio varies over single compositional zones. Below the Néel temperature, a magnetic field between 1.5 T and 2 T parallel to the a-axis causes a 180° spin-flip, reaching the saturation (5.25 μB pfu) toward high magnetic fields.

  15. 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

  16. 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.

  17. 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

  18. Structure-property relations of orthorhombic [(CH3)3NCH2COO]2(CuCl2)3 · 2H2 O

    NASA Astrophysics Data System (ADS)

    Haussühl, Eiken; Schreuer, Jürgen; Wiehl, Leonore; Paulsen, Natalia

    2014-04-01

    Large single crystals of orthorhombic [(CH3)3NCH2COO]2(CuCl2)3 · 2H2 O with dimensions up to 40×40×30 mm3 were grown from aqueous solutions. The elastic and piezoelastic coefficients were derived from ultrasonic resonance frequencies and their shifts upon variation of pressure, respectively, using the plate-resonance technique. Additionally, the coefficients of thermal expansion were determined between 95 K and 305 K by dilatometry. The elastic behaviour at ambient conditions is dominated by the 2-dimensional network of strong hydrogen bonds within the (001) plane leading to a corresponding pseudo-tetragonal anisotropy of the longitudinal elastic stiffness. The variation of elastic properties with pressure, however, as well as the thermal expansion shows strong deviations from the pseudo-tetragonal symmetry. These deviations are probably correlated with tilts of the elongated tri-nuclear betaine-CuCl2-water complexes. Neither the thermal expansion nor the specific heat capacity gives any hint on a phase transition in the investigated temperature range.

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

    DOE PAGES

    O'Neal, Kenneth R.; Brinzari, Tatiana V.; Wright, Joshua B.; ...

    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

  20. Derivation of force field parameters for SnO2-H2O surface systems from plane-wave density functional theory calculations.

    PubMed

    Bandura, A V; Sofo, J O; Kubicki, J D

    2006-04-27

    Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO2 (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H2O present. A classical interatomic force field has been developed to describe bulk SnO2 and SnO2-H2O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO2 are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H2O molecules agree well between the ab initio and force field predictions. H2O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.

  1. Molecular simulation of CH4, CO2, H2O and N2 molecules adsorption on heterogeneous surface models of coal

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Qiang; He, Xu; Qiu, Nian-Xiang; Yang, Xin; Tian, Zhi-Yue; Li, Mei-Jun; Xue, Ying

    2016-12-01

    Using the density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation, the adsorptions of each of an individual gas molecule (CH4, CO2, H2O or N2) and their mixed gases on heterogeneous surface models of coal (HSMC) have been investigated systematically. The GCMC calculations show that the amount of gases adsorbed increases gradually with the rise of pressures and tends to be gently adsorption equilibrium after high pressure as well as decreases step by step with the coverages from 3.125% to 50% or with moisture range from 0.84 to 23.57 mmol/g at room temperature and pressure up to 10 MPa. In mixed gases, we also found that CO2 preferentially adsorbs at importantly greater loadings than CH4 and N2, whereas CH4 is more preferentially adsorbed than N2 on HSMC. The presence of N2 no significantly effect on CH4 and CO2 adsorption, particularly for CO2. Meanwhile, a trace amount of CH4 and/or CO2 in mixtures is easy to dissolve in H2O or to form CH4 or CO2 clathrates while a large number of N2 molecules exist in containing moisture systems of HSMC.

  2. 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.

  3. 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.

  4. 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.

  5. An ammonium iron(II) pyrophosphate, (NH4)2[Fe3(P2O7)2(H2O)2], with a layered structure

    PubMed Central

    Liu, Biao; Zhang, Xin; Wen, Lei; Sun, Wei; Huang, Ya-Xi

    2012-01-01

    Diammonium diaquabis(phosphato)triferrate(II), (NH4)2[Fe3(P2O7)2(H2O)2], was synthesized under solvo­thermal conditions at 463 K. The crystal structure, isotypic to its Mn and Ni analogues, is built from iron pyrophosphate layers parallel to (100), which are linked by ammonium ions sitting in the inter­layer space via O—H⋯O and N—H⋯O hydrogen bonds. There are two crystallographic Fe sites in the crystal structure, one at a special position (2a, ), the other at a general position (4e, 1). The former Fe atom on the inversion centre is coordinated by six O atoms, forming an FeO6 octa­hedron, while the latter is coordinated by five phosphate O atoms and one water mol­ecule, forming an FeO5(H2O) octa­hedron. Each FeO6 octa­hedron shares trans edges with two FeO5(H2O) octa­hedra, forming a linear trimeric unit. These trimers share the lateral edges of FeO5(H2O) with other trimers, forming a zigzag chain running along [010]. The zigzag chains are further linked by P2O7 groups into a layered structure parallel to (100). PMID:22259314

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

    PubMed

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

    2013-11-08

    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.

  7. 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.

  8. Glyoxal photodissociation. An ab initio direct classical trajectory study of C2H2O2→H2+2 CO

    NASA Astrophysics Data System (ADS)

    Li, Xiaosong; Millam, John M.; Schlegel, H. Bernhard

    2001-05-01

    Unimolecular dissociation of glyoxal via a three-body fragmentation channel has been studied by direct classical trajectory calculations using Hartree-Fock (HF) and hybrid density functional methods (BH&HLYP, B3LYP) with split valence and polarized basis sets [HF/3-21G, BH&HLYP/6-311G(d,p) and B3LYP/6-311G(d,p)]. The transition state for C2H2O2→H2+2 CO has a dihedral angle of 90-110° between the carbonyl groups and a calculated barrier of ˜59 kcal/mol above the trans conformer. To simulate the experimental conditions, trajectories were started from a microcanonical ensemble at the transition state with 4, 8, and 16 kcal/mol excess energy distributed among the vibrational modes and the transition vector. In agreement with experiment, the CO rotational distribution is very broad with a high . However, the calculations yielded more CO vibrational excitation for the triple dissociation channel than observed for all channels combined. Hydrogen is produced with low J but significant vibrational excitation, in accord with experiment. Similar to trajectory studies on H2CO→H2+CO, there is a good correlation between the energy released along the part of the reaction path where most of the H2 bond length change occurs and the average vibrational excitation of the H2 products.

  9. 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.

  10. Synthesis, Structure Analysis, and Characterization of a New Thiostannate, (C(12)H(25)NH(3))(4)[Sn(2)S(6)].2H(2)O.

    PubMed

    Li, Jianquan; Marler, Bernd; Kessler, Henri; Soulard, Michel; Kallus, Stefan

    1997-10-08

    A new thiostannate, (C(12)H(25)NH(3))(4)[Sn(2)S(6)].2H(2)O, was synthesized from SnCl(4), Na(2)S, and dodecylamine (DDA) in the ethanol-water two-solvent system at room temperature. First a suspension was obtained. With increasing crystallization time, single crystals up to several millimeters in size were found at the bottom of the vessel. The compound was characterized by single-crystal X-ray diffraction, solid state (119)Sn CPMAS NMR and (13)C CPMAS NMR, IR absorption spectroscopy, and thermal analysis. The crystal data are a = 7.533(2) Å, b = 10.162(2) Å, c = 21.688(4) Å, alpha = 101.22(3) degrees, beta = 90.76(3) degrees, gamma = 101.82(3) degrees, triclinic, space group = P&onemacr;, and Z = 1. The structure consists of one [Sn(2)S(6)](4)(-) anion, four n-dodecylammonium cations, and two water molecules per unit cell. The [Sn(2)S(6)](4)(-) dimers are formed by two edge-sharing [SnS(4)] tetrahedra. The hydrocarbon chains of the cations are straight with the chain direction running parallel to [001]. The chains are in van der Waals contact to each other with the nitrogen atoms pointing in opposite directions for neighboring chains. The positions of all hydrogen atoms were determined; in particular three positions were found which may suggest that the nitrogen atoms are protonated to form cationic groups. The nonorganic constituents of the structure, i.e., anions, water molecules, and ammonium groups, interact to form an infinite layer-like unit parallel to (001).

  11. 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.

  12. 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.

  13. Synthesis and comparative study of Co(pym)(VO3)2 and [Co(H2O)2(VO3)2]·2H2O.

    PubMed

    Larrea, Edurne S; Mesa, José L; Pizarro, José L; Fernández de Luis, Roberto; Rodríguez Fernández, Jesús; Rojo, Teófilo; Arriortua, María I

    2012-12-14

    The three-dimensional Co(pym)(VO(3))(2), 1, hybrid compound, where pym is pyrimidine, has been synthesized under mild hydrothermal conditions at 120 °C. The compound has been characterized by FT-IR spectroscopy, elemental analysis, thermogravimetric measurements, thermodiffractometry, UV-Vis spectroscopy, temperature-dependent magnetic susceptibility and magnetization, and finally a study of specific heat has been performed. The crystal structure of 1 was solved using single-crystal X-ray diffraction data, taking into account that the crystals of this compound are twins of two components. It crystallizes in the monoclinic system, space group C2/c, a = 12.899(5) Å, b = 9.859(2) Å, c = 7.051(1) Å, β = 111.41(3)°, Z = 4. The crystal structure is built up from edge sharing VO(5) trigonal bipyramid double chains and [CoO(4)pym](n) chains. This resembles the structure of the [Co(H(2)O)(2)(VO(3))(2)]·2H(2)O compound, 2. For this reason a comparative study of their properties was carried out. Magnetic measurements of 1, performed in the 2.0 to 300 K range, reveal the existence of a weak ferromagnetic order near 3 K. This fact was confirmed with magnetization measurements, which show irreversibility characteristic of soft ferromagnets. Magnetic measurements of 2 show a 3D antiferromagnetic ordering at 2.5 K. The magnetization shows a small change of curvature indicating the occurrence of a metamagnetic transition. Specific heat measurements of both compounds confirm the 3D nature of the magnetic order. The comparative study of the magneto-structural correlations reveals that the pyrimidine molecules are responsible for the different magnetic behaviour between 1 and 2.

  14. 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.

  15. 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.

  16. 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

    2016-04-07

    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.

  17. 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.

  18. 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.

  19. Theoretical study of the gas-phase reactions of iodine atoms ((2)P(3/2)) with H(2), H(2)O, HI, and OH.

    PubMed

    Canneaux, Sébastien; Xerri, Bertrand; Louis, Florent; Cantrel, Laurent

    2010-09-02

    The rate constants of the reactions of iodine atoms with H(2), H(2)O, HI, and OH have been estimated using 39, 21, 13, and 39 different levels of theory, respectively, and have been compared to the available literature values over the temperature range of 250-2500 K. The aim of this methodological work is to demonstrate that standard theoretical methods are adequate to obtain quantitative rate constants for the reactions involving iodine-containing species. Geometry optimizations and vibrational frequency calculations are performed using three methods (MP2, MPW1K, and BHandHLYP) combined with three basis sets (cc-pVTZ, cc-pVQZ, and 6-311G(d,p)). Single-point energy calculations are performed with the highly correlated ab initio coupled cluster method in the space of single, double, and triple (pertubatively) electron excitations CCSD(T) using the cc-pVnZ (n = T, Q, and 5), aug-cc-pVnZ (n = T, Q, and 5), 6-311G(d,p), 6-311+G(3df,2p), and 6-311++G(3df,3pd) basis sets. Canonical transition state theory with a simple Wigner tunneling correction is used to predict the rate constants as a function of temperature. CCSD(T)/cc-pVnZ//MP2/cc-pVTZ (n = T and Q), CCSD(T)/6-311+G(3df,2p)//MP2/6-311G(d,p), and CCSD(T)/6-311++G(3df,3pd)//MP2/6-311G(d,p) levels of theory provide accurate kinetic rate constants when compared to available literature data. The use of the CCSD(T)/cc-pVQZ//MP2/cc-pVTZ and CCSD(T)/6-311++G(3df,3pd) levels of theory allows one to obtain a better agreement with the literature data for all reactions with the exception of the I + H(2) reaction R(1) . This computational procedure has been also used to predict rate constants for some reactions where no available experimental data exist. The use of quantum chemistry tools could be therefore extended to other elements and next applied to develop kinetic networks involving various fission products, steam, and hydrogen in the absence of literature data. The final objective is to implement the kinetics of gaseous

  20. Magma degassing: new experiments on CO2, H2O, S and Cl between basaltic melt and fluid and development of a new thermodynamical model

    NASA Astrophysics Data System (ADS)

    Lesne, P.; Kohn, S.; Blundy, J.; Witham, F.; Behrens, H.; Botcharnikov, R. E.

    2009-12-01

    Many volcanoes are monitored and one of the main tools for predicting eruptions is analysis of the amount and compositions of gases which are emitted. In particular, measurements of SO2 and HCl are widely used, as there is normally very little SO2 or HCl in the atmosphere. In contrast, it is hard to distinguish between water and carbon dioxide released by the volcano because water and carbon dioxide are already in the atmosphere. In addition, melt inclusions can be analysed for all the dissolved gases and the pre-eruptive history of rising magma losing its dissolved gases can be worked out. Both types of measurements are very useful, but to make the most of them we need to fully understand how gases are released from the molten magma, and at what depth in the volcano. The aim of this research is therefore to study how much of each type of gas can be dissolved in the molten rock, and how the different concentrations of each gas affects the exsolution of the others. We have developed a method which involves experimentally simulating the decompression that occurs when magma ascends beneath a volcano whereby basaltic melt is equilibrated with a C-H-O-S-Cl fluid phase. Experiments were performed in an internal heated pressure vessel, at 1150°C and between 400MPa and 25MPa under oxidized conditions. To reproduce the degassing path of basaltic melt in a closed system, the initial volatile contents are always the same for each experiment. Then, quenched liquid was analysed for both major (CO2, H2O) and minor (S, Cl) components using a range of state-of-the-art analytical techniques. The composition of the fluid phase was determined by mass balance calculations. This study has elucidated, for the first time, the way in which the degassing of S and Cl from basaltic volcanoes is influenced by the presence of H2O and CO2. Water and carbon dioxide data were compared to previous H2O-CO2 models of degassing (Dixon, 1997; Newman and Lowenstern, 2002; Papale et al., 2006): these

  1. Jensenite, Cu3 Te (super 6+) O6 .2H2O, a new mineral species from the Centennial Eureka Mine, Tintic District, Juab County, Utah

    USGS Publications Warehouse

    Roberts, Andrew C.; Grice, Joel D.; Groat, Lee A.; Criddle, Alan J.; Gault, Robert A.; Erd, Richard C.; Moffatt, Elizabeth A.

    1996-01-01

    Jensenite, ideally Cu 3 Te (super 6+) O 6 .2H 2 O, is monoclinic, P2 1 /n (14), with unit-cell parameters refined from powder data: a 9.204(2), b 9.170(2), c 7.584(1) Aa, beta 102.32(3) degrees , V 625.3(3) Aa 3 , a:b:c 1.0037:1:0.8270, Z = 4. The strongest six reflections of the X-ray powder-diffraction pattern [d in Aa(I)(hkl)] are: 6.428(100)(101,110), 3.217(70)(202), 2.601(40)(202), 2.530(50)(230), 2.144(35)(331) and 1.750(35)(432). The mineral is found on the dumps of the Centennial Eureka mine, Juab County, Utah, where it occurs as isolated crystals or as groups of crystals on drusy white quartz. Associated minerals are mcalpineite, xocomecatlite and unnamed Cu(Mg,Cu,Fe,Zn) 2 Te (super 6+) O 6 .6H 2 O. Individual crystals of jensenite are subhedral to euhedral, and form simple rhombs that are nearly equant. Some crystals are slightly elongate [101], with a length-to-width ratio up to 2:1. The largest crystal is approximately 0.4 mm in size; the average size is between 0.1 and 0.2 mm. Cleavage {101} fair. Forms are: {101} major; {110} medium; {100} minor; {301}, {201}, {203}, {102}, {010} very small. The mineral is transparent, emerald green, with a less intense streak of the same color and an uneven fracture. Jensenite is adamantine, brittle and nonfluorescent; H (Mohs) 3-4; D (calc.) 4.78 for the idealized formula, 4.76 g/cm 3 for the empirical formula. In a polished section, jensenite is very weakly bireflectant and nonpleochroic. In reflected plane-polarized light in air, it is a nondescript grey, and in oil, it is a much darker grey in color with a brownish tint, with ubiquitous bright green internal reflections. Anisotropy is not detectable. Measured values of reflectance, in air and in oil, are tabulated. Electron-microprobe analyses yielded CuO 50.91, ZnO 0.31, TeO 3 38.91, H 2 O (calc.) [8.00], total [98.13] wt.%. The empirical formula, derived from crystal-structure analysis and electron-microprobe analyses, is (Cu (sub 2.92) Zn (sub 0.02) ) (sub

  2. 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.

  3. FT-Raman and high-pressure infrared spectroscopic studies of dicalcium phosphate dihydrate (CaHPO 4·2H 2O) and anhydrous dicalcium phosphate (CaHPO 4)

    NASA Astrophysics Data System (ADS)

    Xu, Jingwei; Butler, Ian S.; Gilson, Denis F. R.

    1999-12-01

    The FT-Raman spectra and the pressure dependence of the infrared spectra of the hydrated and anhydrous forms of dicalcium phosphate, CaHPO 4 · 2H 2O and CaHPO 4, have been studied. The hydrated salt exhibits a phase transition at 21 kbar (1.0 kbar=0.1 Gpa) but no high pressure transition was observed for anhydrous dicalcium phosphate. The O-H stretching frequencies of the water molecules in CaHPO 4·2H 2O all showed negative pressure dependences and correlate with the O ⋯O distances. The PO-H stretch increased with increasing pressure, indicating a strong hydrogen bond. The frequencies associated with the phosphate ion showed a normal pressure dependence.

  4. Nqrs Data for C3H10INO6 [C3H7NO2·HIO3·(1/2)(H2O)] (Subst. No. 0642)

    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 C3H10INO6 [C3H7NO2·HIO3·(1/2)(H2O)] (Subst. No. 0642)

  5. Synthesis, crystal structure and properties of a new bi-dentate decavanadate [Cu(en) 2H 2O] 2[H 2V 10O 28]·12H 2O

    NASA Astrophysics Data System (ADS)

    Ma, Huiyuan; Meng, Xin; Sha, Jingquan; Pang, Haijun; Wu, Lizhou

    2011-05-01

    A new bi-dentate decavanadate compound formulated [Cu(en) 2H 2O] 2[H 2V 10O 28]·12H 2O (en = ethylenediamine) ( 1) has been hydrothermally synthesized and structurally characterized. And 1 crystallizes in the triclinic, space group P-1 with a = 10.2606(5) Å, b = 13.4690(6) Å, c = 15.2084(7) Å, α = 102.8150(1)°, β = 91.2380(1)°, γ = 92.1010(1)°, V = 2047.12(2) Å 3, R1( I > 2 σ( I) = 0.0511), and Z = 2. X-ray diffraction analysis reveals that 1 is constructed from bi-dentate decavanadate formed by decavanadate clusters coordinated to [Cu(en) 2H 2O] 2+ complexes and free water molecules. Furthermore, a three-dimensional (3D) framework is achieved in 1via hydrogen bonds between O/N atoms and H atoms of the neighboring [Cu(en) 2H 2O] 2[H 2V 10O 28] subunits. The UV-vis spectrum, fluorescent and electrochemical properties of 1 in aqueous solution are also studied.

  6. 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

  7. Separation and characterization of the two diastereomers for [Gd(DTPA-bz-NH2)(H2O)]2-, a common synthon in macromolecular MRI contrast agents: their water exchange and isomerization kinetics.

    PubMed

    Burai, László; Tóth, Eva; Sour, Angélique; Merbach, André E

    2005-05-16

    Chiral, bifunctional poly(amino carboxylate) ligands are commonly used for the synthesis of macromolecular, Gd(III)-based MRI contrast agents, prepared in the objective of increasing relaxivity or delivering the paramagnetic Gd(III) to a specific site (targeting). Complex formation with such ligands results in two diastereomeric forms for the complex which can be separated by HPLC. We demonstrated that the diastereomer ratio for Ln(III) DTPA derivatives (approximately 60:40) remains constant throughout the lanthanide series, in contrast to Ln(III) EPTPA derivatives, where it varies as a function of the cation size with a maximum for the middle lanthanides (DTPA(5-) = diethylenetriaminepentaacetate; EPTPA(5-) = ethylenepropylenetriaminepentaacetate). The interconversion of the two diastereomers, studied by HPLC, is a proton-catalyzed process (k(obs) = k(1)[H(+)]). It is relatively fast for [Gd(EPTPA-bz-NH(2))(H(2)O)](2-) but slow enough for [Gd(DTPA-bz-NH(2))(H(2)O)](2-) to allow investigation of pure individual isomers (isomerization rate constants are k(1) = (3.03 +/- 0.07) x 10(4) and 11.6 +/- 0.5 s(-1) M(-1) for [Gd(EPTPA-bz-NH(2))(H(2)O)](2)(-) and [Gd(DTPA-bz-NH(2))(H(2)O)](2-), respectively). Individual water exchange rates have been determined for both diastereomers of [Gd(DTPA-bz-NH(2))(H(2)O)](2-) by a variable-temperature (17)O NMR study. Similarly to Ln(III) EPTPA derivatives, k(ex) values differ by a factor of 2 (k(ex)(298) = (5.7 +/- 0.2) x 10(6) and (3.1 +/- 0.1) x 10(6) s(-1)). This variance in the exchange rate has no consequence on the proton relaxivity of the two diastereomers, since it is solely limited by fast rotation. However, such difference in k(ex) will affect proton relaxivity when these diastereomers are linked to a slowly rotating macromolecule. Once the rotation is optimized, slow water exchange will limit relaxivity; thus, a factor of 2 in the exchange rate can lead to a remarkably different relaxivity for the diastereomer complexes

  8. Investigation of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-plasticizer-H(2)O systems by X-ray diffraction.

    PubMed

    Carazeanu, Ionela; Chirila, Elisabeta; Georgescu, Maria

    2002-06-10

    The development of the hydration process in 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system is studied by X-ray diffraction in the presence of varying contents of new plasticizer admixtures belonging to the lignosulphonates class (calcium lignosuphonate-LSC) and condensates melamine formaldehyde sulfonated class-MSF (VIMC-11). The plasticizer admixtures were added in proportion of 0.1-1% solid substance. The influence of the plasticizer admixtures on the hydration process with increasing time is observed and it is shown to depend on the nature and content of the admixtures and the reaction time. The strong adsorption of admixtures on the surfaces on the anhydrous or partially hydrated particles of the system can explain the influence of the admixtures upon the kinetics of the hydration process retardation or acceleration. These plasticizer admixtures influence also the evolution of the hydrated compounds and forming of the hardening structure in the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system; their proportion in the system and the considered length of hardening are correlated. In the 3CaO.Al(2)O(3)-CaSO(4) . 2H(2)O-H(2)O system there are two different influences of the plasticizer admixtures upon the hydration process. One is a delaying action, as a result of plasticizer adsorption on the surface of the anhydrous and hydrated compound particles and another one is the intensifying action due to the stronger dispersion of the particles in aqueous medium.

  9. 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.

  10. 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.

  11. 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)

  12. 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.

  13. An environmentally benign solvothermal method for the synthesis of nanostructured Cd5(OH)8(NO3)2(H2O)2: templates for the generation of nanoporous CdO materials with photocatalytic properties.

    PubMed

    Yang, Zai-Xing; Zhong, Wei; Zhang, Lei; Au, Chak-Tong; Dai, Hong-Xing; Du, You-Wei

    2011-04-01

    Using Cd(NO(3))(2)·4H(2)O as a precursor and ethanol/water as the solvent, we synthesized Cd(5)(OH)(8)(NO(3))(2)(H(2)O)(2) nanowires and nanobelts through a simple solvothermal method. Unlike the conventional oil-water surfactant approach, the adopted method is biologically safe, simple and environmentally benign. The morphology and size of the obtained materials were studied by FESEM. The results revealed that it is possible to assemble nanowires into microblocks by changing the ethanol/water ratio. Furthermore, the results of XRD investigation suggested that the change of ethanol/water ratio can have an influence on the crystalloid phases of Cd(5)(OH)(8)(NO(3))(2)(H(2)O)(2). Through calcination of the as-synthesized compounds in air, nanoporous CdO can be generated. We found that the as-obtained CdO materials are photocatalytically active in the degradation of methylene blue. It is envisaged that this environmentally benign method is also suitable for the synthesis of nanostructures of other oxides such as MgO and CuO.

  14. From hydrated Ni3(OH)2(C8H4O4)2(H2O)4 to anhydrous Ni2(OH)2(C8H4O4): impact of structural transformations on magnetic properties.

    PubMed

    Mesbah, Adel; Rabu, Pierre; Sibille, Romain; Lebègue, Sébastien; Mazet, Thomas; Malaman, Bernard; François, Michel

    2014-01-21

    Dehydration of the hybrid compound [Ni3(OH)2(tp)2(H2O)4] (1) upon heating led to the sequential removal of coordinated water molecules to give [Ni3(OH)2(tp)2(H2O)2] (2) at T1 = 433 K and thereafter anhydrous [Ni2(OH)2(tp)] (3) at T2 = 483 K. These two successive structural transformations were thoroughly characterized by powder X-ray diffraction assisted by density functional theory calculations. The crystal structures of the two new compounds 2 and 3 were determined. It was shown that at T1 (433 K) the infinite nickel oxide chains built of the repeating structural unit [Ni3(μ3-OH)2](4+) in 1 collapse and lead to infinite porous layers, forming compound 2. The second transformation at T2 (483 K) gave the expected anhydrous compound 3, which is isostructural with Co2(OH)2(tp). These irreversible transitions directly affect the magnetic behavior of each phase. Hence, 1 was found to be antiferromagnetic at TN = 4.11 K, with metamagnetic behavior with a threshold field Hc of ca. 0.6 T. Compound 2 exhibits canted antiferromagnetism below TN = 3.19 K, and 3 is ferromagnetic below TC = 4.5 K.

  15. Comprehensive copper ion hydration: experimental and theoretical investigation of Cu2+(H2O)n, Cu+(H2O)n, CuOH+(H2O)n

    NASA Astrophysics Data System (ADS)

    Sweeney, Andrew

    Guided ion beam tandem mass spectrometry is used to probe the kinetic energy dependence of both Cu2+(H2O)n, where n = 5--10, and CuOH+(H2O)n, where n = 0--4 colliding with Xe. The resulting cross sections are analyzed using statistical models to yield 0 K bond dissociation energies (BDEs). The primary dissociation pathway for Cu2+(H2O)n consists of water loss followed by the sequential loss of additional waters at higher energies until n = 7, at which point charge separation to form CuOH+(H2O) m + H+(H2O)n-m-2 is energetically favored. The primary dissociation pathway for CuOH+(H 2O)n is also water loss and is followed by the sequential loss of additional waters at higher energies until n = 1, at which point OH loss become competitive. The BDEs for loss of water and OH from CuOH +(H2O) are combined in a thermodynamic cycle with literature values to derive BDEs for the loss of OH from CuOH+(H 2O)n, where n = 0, 2--4. Infrared multiple photon dissociation (IRPD) spectroscopy is performed on CuOH+(H2O)n, where n = 2--9. These spectra are characterized through comparison to theoretical spectra of low energy isomers. It is found that CuOH+(H2O) n prefers a 4-coordinate inner shell, although contributions from 5-coordinate geometries cannot be ruled out in most cases and are clearly present for n = 7. This preference is found in the Cu2+(H2O) n system as well and differs from the Cu+(H2O) n system, which prefers a 2-coordinate inner shell. Electronic structure calculations are further employed to yield BDEs which agree reasonably well with experimental values. A method for modeling kinetic energy release distributions (KERD) on a guided ion beam tandem mass spectrometer is proposed. This method achieves reasonable agreement with dissociations occurring over loose transition states when reactants have little energy in excess of the dissociation threshold. Current limitations and future possibilities of this method are discussed in detail.

  16. Structural study of hydrated/dehydrated manganese thiophene-2,5-diphosphonate metal organic frameworks, Mn2(O3P-C4H2S-PO3)·2H2O.

    PubMed

    Rueff, Jean-Michel; Perez, Olivier; Pautrat, Alain; Barrier, Nicolas; Hix, Gary B; Hernot, Sylvie; Couthon-Gourvès, Hélène; Jaffrès, Paul-Alain

    2012-10-01

    Synthesis of thiophene-2,5-diphosphonic acid 2 is reported, and its use for synthesis of the original pristine materials Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 3 is reported. The structure of material 3 has been fully resolved from single-crystal X-ray diffraction. Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 3 crystallizes in a monoclinic cell (space group P2) with the following parameters: a = 11.60(1) Å, b = 4.943(5) Å, c = 19.614(13) Å, β = 107.22°. A noticeable feature of the structure of compound 3 is the orientation of the thiophene heterocycles that adopt two different orientations in two successive layers (along c). Thermal analysis of compound 3 indicates that the water molecules are easily removed from 160 to 230 °C while the dehydrated structure is stable up to 500 °C. The dehydrated compound obtained from 3 can be rehydrated to give the polymorphic compound Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 4, which crystallizes in an orthorhombic cell (space group Pnam) with the following parameters: a = 7.5359(3) Å, b = 7.5524(3) Å, c = 18.3050(9) Å. The main difference between the structures of 3 and 4 arises from both the orientation of the thiophene rings (herringbone-type organization in 4) and the structure of the inorganic layers. The thiophene-2,5-diphosphonic acid moieties engaged in materials 3 and 4 adopt a different orientation likely due to rotation around the P-C bonds and via the dehydrated state 5, which is likely more flexible than the hydrated states. Study of the magnetic properties performed on compound 3 and 4 and on the dehydrated compounds Mn(2)(O(3)P-C(4)H(2)S-PO(3)) 5 complemented by the structural study has permitted us to characterize the antiferromagnetic ground state of sample 3, a weak ferromagnetic component in sample 4, and complete paramagnetic behavior in sample 5.

  17. Understanding the mechanism of action of the novel SSAO substrate (C7NH10)6(V10O28).2H2O, a prodrug of peroxovanadate insulin mimetics.

    PubMed

    Yraola, Francesc; García-Vicente, Silvia; Marti, Luc; Albericio, Fernando; Zorzano, Antonio; Royo, Miriam

    2007-06-01

    A new vanadium salt, hexakis(benzylammonium) decavanadate (V) dihydrate (C(7)NH(10))(6)(V(10)O(28)).2H(2)O (1), has been synthesized as well as characterized chemically and biologically. An in vitro enzyme assay revealed that compound 1 is oxidized to the same extent as a combination of benzylamine and vanadate by the enzyme semicarbazide-sensitive amine oxidase (SSAO), and therefore can be considered an SSAO substrate. It also stimulates glucose uptake in isolated rat adipocytes in a dose-dependent manner. We describe here the results of (51)V-NMR experiments that, combined with the in vitro results, corroborate that compound 1 could act as a prodrug of di-peroxovanadate ([V(OH)(2)(OO)(2)(OH)(2)](2-)) insulin mimetics.

  18. 13C-NMR studies of the paramagnetic and charge-ordered states of the organic superconductor β''-(BEDT-TTF)3Cl2·2H2O under pressure

    NASA Astrophysics Data System (ADS)

    Nagata, Sanato; Ogura, Takashi; Kawamoto, Atsushi; Taniguchi, Hiromi

    2011-07-01

    β''-(BEDT-TTF)3Cl2·2H2O [BEDT-TTF: b̲is-(e̲thylened̲it̲hio)t̲etrat̲hiaf̲ulvalene] is superconductive under pressures, whereas the salt exhibits metal-insulator (MI) transition under ambient pressure. The insulator phase in the salt was examined using the charge density wave (CDW) phase that was obtained from band calculation. The charge-ordered (CO) state was recently proposed as the insulator phase of the salt, and the mechanism of superconductivity intermediated by charge fluctuation was suggested. We accessed 13C-NMR on β''-(BEDT-TTF)3Cl2·2H2O at ambient pressure and under pressure up to 1.6 GPa. At ambient pressure, the NMR spectrum changed at approximately 100 K. Three isolated peaks appeared at low temperatures, suggesting that the CO state exists below 100 K, and spin-gap behavior was observed. By analyzing the chemical shift, the charges on the three sites were estimated as ˜+0.4e, ˜+0.6e, and ˜+1.0e. The ratio of peak intensity and unsymmetrical peak position suggest the CO state with some symmetry breaking. When pressure is applied, the splitting of the NMR peaks in the CO state is reduced. The salt finally exhibits superconductivity at 1.6 GPa, spin-gap behavior observed at (T1T)-1 below 1.3 GPa suddenly disappears, whereas the NMR spectrum predicts that charge disproportionation coexists with superconductivity. The suppression of the spin-singlet formation observed in (T1T)-1 at 1.6 GPa suggests the metallic state with the charge disproportionation and the CO instability with some symmetry breaking.

  19. 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.

  20. 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.

  1. 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

  2. Thermodynamic data of lawsonite and zoisite in the system CaO-Al2O3-SiO2-H2O based on experimental phase equilibria and calorimetric work

    NASA Astrophysics Data System (ADS)

    Grevel, Klaus-Dieter; Schoenitz, Mirko; Skrok, Volker; Navrotsky, Alexandra; Schreyer, Werner

    2001-08-01

    The enthalpy of drop-solution in molten 2PbO.B2O3 of synthetic and natural lawsonite, CaAl2(Si2O7)(OH)2.H2O, was measured by high-temperature oxide melt calorimetry. The enthalpy of formation determined for the synthetic material is ΔfHOxides=-168.7+/-3.4 kJ mol-1, or ΔfH0298=-4,872.5+/-4.0 kJ mol-1. These values are in reasonable agreement with previously published data, although previous calorimetric work yielded slightly more exothermic data and optimisation methods resulted in slightly less exothermic values. The equilibrium conditions for the dehydration of lawsonite to zoisite, kyanite and quartz/coesite at pressures and temperatures up to 5 GPa and 850 °C were determined by piston cylinder experiments. These results, other recent phase equilibrium data, and new calorimetric and thermophysical data for lawsonite and zoisite, Ca2Al3(SiO4)(Si2O7)O(OH), were used to constrain a mathematical programming analysis of the thermodynamic data for these two minerals in the chemical system CaO-Al2O3-SiO2-H2O (CASH). The following data for lawsonite and zoisite were obtained: ΔfH0298 (lawsonite)=-4,865.68 kJ mol-1 , S0298 (lawsonite)=229.27 J K-1 mol-1 , ΔfH0298 (zoisite)=-6,888.99 kJ mol-1 , S0298 (zoisite)=297.71 J K-1 mol-1 . Additionally, a recalculation of the bulk modulus of lawsonite yielded K=120.7 GPa, which is in good agreement with recent experimental work.

  3. 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

    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.

  4. Requirements for functional models of the iron hydrogenase active site: D2/H2O exchange activity in ((mu-SMe)(mu-pdt)[Fe(CO)2(PMe3)]2+)[BF4-].

    PubMed

    Georgakaki, Irene P; Miller, Matthew L; Darensbourg, Marcetta Y

    2003-04-21

    Hydrogen uptake in hydrogenase enzymes can be assayed by H/D exchange reactivity in H(2)/D(2)O or H(2)/D(2)/H(2)O mixtures. Diiron(I) complexes that serve as structural models for the active site of iron hydrogenase are not active in such isotope scrambling but serve as precursors to Fe(II)Fe(II) complexes that are functional models of [Fe]H(2)ase. Using the same experimental protocol as used previously for ((mu-H)(mu-pdt)[Fe(CO)(2)(PMe(3))](2)(+)), 1-H(+) (Zhao et al. J. Am. Chem. Soc. 2001, 123, 9710), we now report the results of studies of ((mu-SMe)(mu-pdt)[Fe(CO)(2)(PMe(3))](2)(+)), 1-SMe(+), toward H/D exchange. The 1-SMe(+) complex can take up H(2) and catalyze the H/D exchange reaction in D(2)/H(2)O mixtures under photolytic, CO-loss conditions. Unlike 1-H(+), it does not catalyze H(2)/D(2) scrambling under anhydrous conditions. The molecular structure of 1-SMe(+) involves an elongated Fe.Fe separation, 3.11 A, relative to 2.58 A in 1-H(+). It is proposed that the strong SMe(-) bridging ligand results in catalytic activity localized on a single Fe(II) center, a scenario that is also a prominent possibility for the enzyme active site. The single requirement is an open site on Fe(II) available for binding of D(2) (or H(2)), followed by deprotonation by the external base H(2)O (or D(2)O).

  5. 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

    2016-04-04

    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

  6. Influence of Gaseous Media Flow in the Dual Ar-H2-H2O/air Atmosphere Setup on the Scale Growth Kinetics of Crofer 22APU Ferritic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Stygar, Mirosław; Dąbrowa, Juliusz; Dziembaj, Piotr; Brylewski, Tomasz

    2017-02-01

    The problem of gaseous media distribution within the metallic interconnects in solid oxide fuel cells (SOFCs) and its influence on the oxidation resistance of the applied materials is currently of great interest. In the presented work, an influence of gas flow within the dual Ar-H2-H2O/air atmosphere experimental setup on the oxidation behavior of the Crofer 22APU ferritic stainless steel was investigated. Examination of the sample oxidized for 1000 h in temperature of 800 °C revealed the presence of coaxial regions on the scale surface, with the differences in scale's thicknesses in those regions being clearly visible. Additionally, the morphology of the surface changed significantly in a function of the radial distance from the sample's center. To further examine the phenomena of uneven gas distribution, a model of the dual-atmosphere setup was created, using Ansys Workbench software. Obtained results suggest that the correlation between scale morphology and distribution of temperature and pressure on the sample's surface, created by gas flow in the system, can be justified.

  7. Hydrothermal synthesis, structural elucidation, spectroscopic studies, thermal behavior and luminescence properties of a new 3-d compound: FeAlF2(C10H8N2)(HPO4)2(H2O)

    NASA Astrophysics Data System (ADS)

    Bouzidia, Nabaa; Salah, Najet; Hamdi, Besma; Ben Salah, Abdelhamid

    2017-04-01

    The study of metal phosphate has been a proactive field of research thanks to its applied and scientific importance, especially in terms of the development of optical devices such as solid state lasers as well as optical fibers. The present paper seeks to investigate the synthesis, crystal structure, elemental analysis and properties of FeAlF2(C10H8N2)(HPO4)2(H2O) compound investigated by spectroscopic studies (FT-IR and FT-Raman), thermal behavior and luminescence. The Hirshfeld surface analysis and 2-D fingerprint plot have been performed to explore the behavior of these weak interactions and crystal cohesion. This investigation shows that the molecules are connected by hydrogen bonds of the type Osbnd H⋯O and Osbnd H⋯F. In addition, the 2,2'‒bipyridine ligand plays a significant role in the construction of 3-D supramolecular framework via π‒π stacking. FT‒IR and FT‒Raman spectra were used so as to ease the responsibilities of the vibration modes of the title compound. The thermal analysis (TGA) study shows a mass loss evolution as a temperature function. Finally, the optical properties were evaluated by photoluminescence spectroscopy.

  8. Novel Process of Simultaneous Removal of Nitric Oxide and Sulfur Dioxide Using a Vacuum Ultraviolet (VUV)-Activated O2/H2O/H2O2 System in A Wet VUV-Spraying Reactor.

    PubMed

    Liu, Yangxian; Wang, Qian; Pan, Jianfeng

    2016-12-06

    A novel process for NO and SO2 simultaneous removal using a vacuum ultraviolet (VUV, with 185 nm wavelength)-activated O2/H2O/H2O2 system in a wet VUV-spraying reactor was developed. The influence of different process variables on NO and SO2 removal was evaluated. Active species (O3 and ·OH) and liquid products (SO3(2-), NO2(-), SO4(2-), and NO3(-)) were analyzed. The chemistry and routes of NO and SO2 removal were investigated. The oxidation removal system exhibits excellent simultaneous removal capacity for NO and SO2, and a maximum removal of 96.8% for NO and complete SO2 removal were obtained under optimized conditions. SO2 reaches 100% removal efficiency under most of test conditions. NO removal is obviously affected by several process variables. Increasing VUV power, H2O2 concentration, solution pH, liquid-to-gas ratio, and O2 concentration greatly enhances NO removal. Increasing NO and SO2 concentration obviously reduces NO removal. Temperature has a dual impact on NO removal, which has an optimal temperature of 318 K. Sulfuric acid and nitric acid are the main removal products of NO and SO2. NO removals by oxidation of O3, O·, and ·OH are the primary routes. NO removals by H2O2 oxidation and VUV photolysis are the complementary routes. A potential scaled-up removal process was also proposed initially.

  9. Crystal growth and morphology of the nano-sized hydroxyapatite powders synthesized from CaHPO 4·2H 2O and CaCO 3 by hydrolysis method

    NASA Astrophysics Data System (ADS)

    Shih, Wei-Jen; Chen, Yung-Feng; Wang, Moo-Chin; Hon, Min-Hsiung

    2004-09-01

    The crystal growth and morphology of the nano-sized hydroxyapatite (HA) powders synthesized from dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) and CaCO3 have been investigated. The nano-sized HA powders were obtained using the hydrolysis of DCPD and CaCO3 with 2.5 M NaOH(aq) at 75°C for 1 h. The only product synthesized from DCPD is HA, and the crystallinity of the HA is improved with increasing annealing temperature. The XRD results show that when heated at 600°C for 4 h, the mixture of the HA and CaO is obtained with CaCO3 addition, having the Ca/P ratio of 1.67. However, when the mixture is heated at 800°C for 4 h, besides the HA and CaO, the NaCaPO4 phase also shows up.

  10. Influence of Gaseous Media Flow in the Dual Ar-H2-H2O/air Atmosphere Setup on the Scale Growth Kinetics of Crofer 22APU Ferritic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Stygar, Mirosław; Dąbrowa, Juliusz; Dziembaj, Piotr; Brylewski, Tomasz

    2016-12-01

    The problem of gaseous media distribution within the metallic interconnects in solid oxide fuel cells (SOFCs) and its influence on the oxidation resistance of the applied materials is currently of great interest. In the presented work, an influence of gas flow within the dual Ar-H2-H2O/air atmosphere experimental setup on the oxidation behavior of the Crofer 22APU ferritic stainless steel was investigated. Examination of the sample oxidized for 1000 h in temperature of 800 °C revealed the presence of coaxial regions on the scale surface, with the differences in scale's thicknesses in those regions being clearly visible. Additionally, the morphology of the surface changed significantly in a function of the radial distance from the sample's center. To further examine the phenomena of uneven gas distribution, a model of the dual-atmosphere setup was created, using Ansys Workbench software. Obtained results suggest that the correlation between scale morphology and distribution of temperature and pressure on the sample's surface, created by gas flow in the system, can be justified.

  11. Second sphere coordination in anion binding: Synthesis, Characterization and X-ray structure of tris(1,10-phenanthroline)cobalt(III) periodate dihydrate, [Co(phen) 3](IO 4) 3·2H 2O

    NASA Astrophysics Data System (ADS)

    Sharma, Raj Pal; Singh, Ajnesh; Brandão, Paula; Felix, Vitor; Venugopalan, Paloth

    2008-10-01

    Single crystals of [Co(phen) 3](IO 4) 3·2H 2O were obtained by dissolving the yellow coloured precipitated product (obtained by slowly mixing the separately dissolved tris(1,10-phenanthroline)cobalt(III) chloride with sodium periodate in aqueous medium in 1:3 molar ratio) in hot water and allowing it to evaporate slowly at room temperature. The newly synthesized complex salt was characterized by elemental analyses, spectroscopic studies (IR, UV/Visible, 1H and 13C NMR), solubility product and conductance measurements. The complex salt crystallizes in the monoclinic space group P2 1/ n with a = 11.6865(3), b = 19.9546(4), c = 16.6808(3) Å, β = 98.4730(10)°, V = 3847.5(6) Å 3, Z = 4. X-ray structure determination revealed an ionic structure consisting of one [Co(phen) 3] 3+, three [IO 4] - ions and two lattice water molecules per asymmetric unit. The six nitrogen atoms, originating from three 1,10-phenanthroline ligands (each bidentate) show distorted octahedral geometry around the central Co(III) metal ion. Supramolecular hydrogen bonding networks between ionic groups [Co-phenCH…Oδ-anion] by second sphere coordination besides electrostatic forces of attraction have been observed that stabilize crystal lattice. The structural studies suggest that [Co(phen) 3] 3+ is a potential anion receptor for the periodate ion, (IO 4) - in aqueous medium.

  12. A shock tube study of OH + H(2)O(2) --> H(2)O + HO(2) and H(2)O(2) + M --> 2OH + M using laser absorption of H(2)O and OH.

    PubMed

    Hong, Zekai; Cook, Robert D; Davidson, David F; Hanson, Ronald K

    2010-05-13

    The rate constants of the reactions: (1) H2O2+M-->2OH+M, (2) OH+H2O2-->H2O+HO2 were measured in shock-heated H(2)O(2)/Ar mixtures using laser absorption diagnostics for H(2)O and OH. Time-histories of H(2)O were monitored using tunable diode laser absorption at 2550.96 nm, and time-histories of OH were achieved using ring dye laser absorption at 306 nm. Initial H(2)O(2) concentrations were also determined utilizing the H(2)O diagnostic. On the basis of simultaneous time-history measurements of OH and H(2)O, k(2) was found to be 4.6 x 10(13) exp(-2630 K/T) [cm(3) mol(-1) s(-1)] over the temperature range 1020-1460 K at 1.8 atm; additional measurements of k(2) near 1 atm showed no significant pressure dependence. Similarly, k(1) was found to be 9.5 x 10(15) exp(-21 250 K/T) [cm(3) mol(-1) s(-1)] over the same temperature and pressure range.

  13. Preparation and studies of new crystals in the K3H(SO4)2-(NH4)3H(SO4)2-H2O system

    NASA Astrophysics Data System (ADS)

    Dmitricheva, E. V.; Makarova, I. P.; Grebenev, V. V.; Dolbinina, V. V.; Verin, I. A.

    2014-05-01

    To elucidate the effect of isomorphic substitution on the kinetics of phase transitions, single crystals of (K x (NH4)1- x ) m H n (SO4)( m + n)/2 · yH2O solid solutions are grown from the K3H(SO4)2-(NH4)3H(SO4)2-H2O system, whose end members are known to undergo superprotonic phase transitions of fundamentally different kinetics. The chemical composition of the single crystals grown is determined by energy dispersive X-ray microanalysis. The thermal and optical behavior of (K,NH4)9H7(SO4)8 · H2O single crystals is studied in the temperature range 295-420 K and the crystal structure at 295 K is determined. A comparison of the results of the studies with data for crystal K9H7(SO4)8 · H2O published earlier shows that the substitution of ammonium for potassium atoms lowers the temperature of the structural phase transition by 8 K.

  14. The first 3D malonate bridged copper [Cu(O2C-CH2-CO2H)2·2H2O]: Structure, properties and electronic structure

    NASA Astrophysics Data System (ADS)

    Seguatni, A.; Fakhfakh, M.; Smiri, L. S.; Gressier, P.; Boucher, F.; Jouini, N.

    2012-03-01

    A new inorganic-organic compound [Cu(O2C-CH2-CO2H)2·2H2O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)-malonic acid-H2O. Its framework is built up through carboxyl bridged copper where CuO6 octahedra are elongated with an almost D4h symmetry (4+2) due to the Jahn-Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2-300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a Ueff value of about 6 eV is necessary for a better correlation with the experiment.

  15. Long-range antiferromagnetic order in malonate-based compounds Na2M(H2C3O4)2·2H2O (M = Mn, Fe, Co, Ni).

    PubMed

    Rousse, G; Radtke, G; Klein, Y; Ahouari, H

    2016-02-14

    The recently discovered metal-malonate compounds of formulae Na2M(H2C3O4)2·2H2O with M = Mn, Fe, Co, Ni are investigated for their magnetic properties. While the Cu-based material is a weak ferromagnet, all other members present antiferromagnetic interactions. Neutron powder diffraction experiments reveal the establishment of a long range magnetic order at low temperature in the Pbca Shubnikov magnetic group. The magnetic structures are characterized by antiferromagnetic layers perpendicular to [001]. These layers are stacked antiparallel (M = Fe) or parallel (M = Mn, Ni) in the (a, c) plane. Magnetic moments are collinear to b for the former and to c for the latter. The M = Co malonate exhibits a non-collinear magnetic structure intermediate between the two latter, with components along b and c. Density functional theory calculations indicate that the dominant magnetic interaction, J1, occurs along a malonate group via a carboxylate and links two transition metals within the same layer, while other interactions (inter- or intra-layer) are much weaker, so that these compounds present the dominant characteristics of 2D-antiferromagnets.

  16. 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.

  17. 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.

  18. Synthesis, structure and physicochemical characterization of the hybrid material [C6H16N2O]2 SnCl6·2Cl·2H2O

    NASA Astrophysics Data System (ADS)

    Belhaj Salah, S.; Pereira da Silva, P. S.; Lefebvre, F.; Ben Nasr, C.; Ammar, S.; Mrad, M. L.

    2017-04-01

    The current study reports the chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel compound [C6H16N2O]2SnCl6·2Cl·2H2O. This compound crystallizes in the triclinic system (space group P - 1, Z = 1) with the following unit cell dimensions: a = 7.9764(9), b = 8.2703(9), c = 12.1103(14)Å, α = 84.469(6), β = 75.679(6), and γ = 64.066(5)°. The structure was solved using 3093 independent reflections down to R = 0.020. The atomic arrangement shows alternation of organic and inorganic entities. The cohesion between these entities is ensured by Nsbnd H…Cl and Osbnd H…Cl hydrogen bonds that build a three-dimensional network. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular interactions. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands. X-ray powder, XPS and UV spectrum have been carried out. The DSC profile shows that the title material exhibits dehydration at 339 K.

  19. Synthesis and characterization of (H2dab)2Cu8Ge4S14·2H2O: An expanded framework based on icosahedral Cu8S12 cluster

    NASA Astrophysics Data System (ADS)

    Zhang, Ren-Chun; Zhang, Chi; Ji, Shou-Hua; Ji, Min; An, Yong-Lin

    2012-02-01

    A new three-dimensional framework copper-thiogermanate, (H2dab)2Cu8Ge4S14·2H2O (1), was prepared under solvothermal condition and characterized by elemental analysis, single-crystal and powder X-ray diffraction, thermogravimetric analysis and UV-vis diffuse reflectance spectroscopy. Compound 1 crystallizes in the monoclinic space group P2(1)/c, a=11.444(4) Å, b=12.984(4) Å, c=12.455(6) Å, β=91.527(1)°, V=1850.2(3) Å3, Z=2. It contains a new three-dimensional Cu-Ge-S framework constructed from icosahedral [Cu8S12]16- clusters linked by [GeS4]4- and dimeric [Ge2S6]4- units, with diprotonated 1,4-dab (1,4-diaminobutane) and H2O molecules located in the intersecting channels. UV-vis reflectance spectroscopy reveals the band gap of compound 1 is 2.5 eV.

  20. New iron(II) spin crossover coordination polymers [Fe(μ-atrz)3]X2·2H2O (X = ClO4¯, BF4¯) and [Fe(μ-atrz)(μ-pyz)(NCS)2]·4H2O with an interesting solvent effect.

    PubMed

    Chuang, Yu-Chun; Liu, Chi-Tsun; Sheu, Chou-Fu; Ho, Wei-Lun; Lee, Gene-Hsiang; Wang, Chih-Chieh; Wang, Chih-Cheh; Wang, Yu

    2012-04-16

    A potential bridging triazole-based ligand, atrz (trans-4,4'-azo-1,2,4-triazole), is chosen to serve as building sticks and incorporated with a spin crossover metal center to form a metal organic framework. Coordination polymers of iron(II) with the formula [Fe(μ-atrz)(3)]X(2)·2H(2)O (where X = ClO(4)(-) (1·2H(2)O) and BF(4)(-) (2·2H(2)O)) in a 3D framework and [Fe(μ-atrz)(μ-pyz)(NCS)(2)]·4H(2)O (3·4H(2)O) in a 2D layer structure were synthesized and structurally characterized. The magnetic measurements of 1·2H(2)O and 2·2H(2)O reveal spin transitions near room temperature; that of 3 exhibits an abrupt spin transition at ~200 K with a wide thermal hysteresis, and the spin transition behavior of these polymers are apparently correlated with the water content of the sample. Crystal structures have been determined both at high spin and at low spin states for 1·2H(2)O, 2·2H(2)O, and 3·4H(2)O. Each iron(II) center in 1·2H(2)O and 2·2H(2)O is octahedrally coordinated with six μ-atrz ligands, which in turn links the other Fe center forming a strong three-dimensional (3D) network; counteranion and water molecules are located in the voids of the lattice. The FeN(6) octahedron of 3·4H(2)O is formed with two atrz, two pyrazine (pyz) ligands, and two NCS(-) ligands, where the ligands atrz and pyz are bridged between iron centers forming a 2D layer polymer. A zigzag chain of water molecules is found between the layers, and there is a distinct correlation between the thermal hysteresis with the amount of water molecules the exist in the crystal.

  1. Topological analysis of void space in phosphate frameworks: Assessing storage properties for the environmentally important guest molecules and ions: CO2, H2O, UO2, PuO2, U, Pu, Sr2+, Cs+, CH4, and H2

    DOE PAGES

    Cramer, Alisha J.; Cole, Jacqueline M.

    2016-06-27

    The entrapment of environmentally important materials to enable containment of polluting wastes from industry or energy production, storage of alternative fuels, or water sanitation, is of vital and immediate importance. Many of these materials are small molecules or ions that can be encapsulated via their adsorption into framework structures to create a host-guest complex. This is an ever-growing field of study and, as such, the search for more suitable porous materials for environmental applications is fundamental to progress. However, many industrial areas that require the use of adsorbents are fraught with practical challenges such as high temperatures, rapid gas expansion,more » radioactivity, or repetitive gas cycling, that the host material must withstand. Inorganic phosphates have a proven history of rigid structures, thermal stability, and are suspected to possess good resistance to radiation over geologic time scales. Furthermore, various experimental studies have established their ability to adsorb small molecules, such as water. In light of this, all known crystal structures of phosphate frameworks with meta- (P3O9) or ultra- (P5O14) stoichiometries are combined in a data-mining survey together with all theoretically possible structures of LnaPbOc (where a, b, c are any integer, and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, or Tm) that are statistically likely to form. Topological patterns within these framework structures are used to assess their suitability for hosting a variety of small guest molecules or ions that are important for environmental applications: CO2, H2O, UO2, PuO2, U, Pu, Sr2+, Cs+, CH4 and H2. A range of viable phosphate-based host-guest complexes are identified from this data-mining and pattern-based structural analysis. Moreover, distinct topological preferences for hosting such guests are found, and metaphosphate stoichiometries are generally preferred over ultraphosphate configurations.« less

  2. 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

  3. Phase equilibria in the system K2O-FeO-MgO-Al2O3-SiO2-H2O-CO2 and the stability limit of stilpnomelane in metamorphosed Precambrian iron-formations

    NASA Astrophysics Data System (ADS)

    Miyano, Takashi; Klein, Cornelis

    1989-08-01

    The phase relations of Al- and Fe-bearing silicates in the system K2O-FeO-MgO-Al2O3-SiO2-H2O-CO2, in the presence of quartz and magnetite, are discussed on the basis of mineralogic and petrologic data from Precambrian iron-formations and blueschist facies meta-ironstone from the Franciscan Formation, California. These relations allow an estimation of the physiochemical conditions during low-grade metamorphism of iron-formations. Petrologic data together with available experimental and predicted thermodynamic data on the associated minerals place the upper stability limit of stilpnomelane in iron-formations at about 430 470° C and 5 6 kilobars. Fe-end member stilpnomelane can persist to a maximum temperature of 500° C and pressures up to 6 7 kilobars, although it is unlikely to occur in metamorphosed iron-formations. In iron-formation occurrences the stilpnomelane stability field is bordered by four equilibrium reactions with the assemblages stilpnomelane-zussmanite-chlorite-minnesotaite, stilpnomelane-zussmanite-chlorite-grunerite, stilpnomelane-biotite-chlorite-grunerite, and stilpnomelane-biotite-almandine-grunerite. The stability field is reduced by increasing X(CO2) and X {Mg/Stil}, and is also a function of a( K +)/ a( H +) in the metamorphic fluid. If the value of a( K +)/ a( H +) is smaller than that defined by the above assemblages, stilpnomelane decomposes to chlorite, but if larger, it is replaced by biotite. At pressures less than 4 kilobars, the zussmanite field is restricted to a very high value of a( K +)/a( H +) (> 5.0 in log units at 1.0 kilobar) where iron-formation assemblages are not stable.

  4. An experimental investigation on the P-T stability of Mg-staurolite in the system MgO-Al2O3-SiO2-H2O

    NASA Astrophysics Data System (ADS)

    Fockenberg, Thomas

    The pressure-temperature stability field of Mg-staurolite, ideally Mg4Al18Si8O46(OH)2, was bracketed for six possible breakdown reactions in the system MgO-Al2O3-SiO2-H2O (MASH). Mg-staurolite is stable at water pressures between 12 and 66 kbar and temperatures of 608-918°C, requiring linear geotherms between 3 and 18°C/km. This phase occurs in rocks that were metamorphosed at high-pressure, low-temperature conditions, e.g. in subducted crustal material, provided they are of appropriate chemical composition. Mg-staurolite is formed from the assemblage chlorite+kyanite+corundum at pressures <24 kbar, whereas at pressures up to 27 kbar staurolite becomes stable by the breakdown of the assemblage Mg-chloritoid+kyanite+corundum. Beyond 27 kbar the reaction Mg-chloritoid + kyanite + diaspore = Mg-staurolite + vapour limits the staurolite field on its low-temperature side. The upper pressure limit of Mg-staurolite is marked by alternative assemblages containing pyrope+topaz-OH with either corundum or diaspore. At higher temperatures Mg-staurolite breaks down by complete dehydration to pyrope+kyanite+corundum and at pressures below 14 kbar to enstatite+ kyanite+corundum. The reaction curve Mg-staurolite=talc+kyanite+corundum marks the low-pressure stability of staurolite at 12kbar. Mg-staurolite does not coexist with quartz because alternative assemblages such as chlorite-kyanite, enstatite-kyanite, talc-kyanite, pyrope-kyanite, and MgMgAl-pumpellyite-kyanite are stable over the entire field of Mg-staurolite.

  5. 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.

  6. 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.

  7. 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.

  8. Sequential hydration energies of the sulfate ion, from determinations of the equilibrium constants for the gas-phase reactions: SO4(H2O)(n)2- = SO4(H2O)(n-1)2- + H2O.

    PubMed

    Blades, Arthur T; Kebarle, Paul

    2005-09-22

    Sequential hydration energies of SO4(H2O)(n)2- were obtained from determinations of the equilibrium constants of the following reactions: SO4(H2O)(n)2- = SO4(H2O)(n-1)2- + H2O. The SO4(2-) ions were produced by electrospray and the equilibrium constants Kn,n-1 were determined with a reaction chamber attached to a mass spectrometer. Determinations of Kn,n-1 at different temperatures were used to obtain DeltaG0n,n-1, DeltaH0 n,n-1, and DeltaS0n,n-1 for n = 7 to 19. Interference of the charge separation reaction SO4(H2O)(n)2- = HSO4(H2O)(n-k)- + OH(H2O)(k-1)- at higher temperatures prevented determinations for n < 7. The DeltaS0n,n-1 values obtained are unusually low and this indicates very loose, disordered structures for the n > or = 7 hydrates. The DeltaH0n,n-1 values are compared with theoretical values DeltaEn,n-1, obtained by Wang, Nicholas, and Wang. Rate constant determinations of the dissociation reactions n,n - 1, obtained with the BIRD method by Wong and Williams, showed relatively lower rates for n = 6 and 12, which indicate that these hydrates are more stable. No discontinuities of the DeltaG0n,n-1 values indicating an unusually stable n = 12 hydrate were observed in the present work. Rate constants evaluated from the DeltaG0n,n-1 results also fail to indicate a lower rate for n = 12. An analysis of the conditions used in the two types of experiments indicates that the different results reflect the different energy distributions expected at the dissociation threshold. Higher internal energies prevail in the equilibrium measurements and allow the participation of more disordered transition states in the reaction.

  9. Experimental investigation of zoisite-clinozoisite phase equilibria in the system CaO-Fe2O3-Al2O3-SiO2-H2O

    NASA Astrophysics Data System (ADS)

    Brunsmann, A.; Franz, G.; Heinrich, W.

    2002-01-01

    The system Ca2Al3Si3O11(O/OH)-Ca2Al2FeSi3O11(O/OH), with emphasis on the Al-rich portion, was investigated by synthesis experiments at 0.5 and 2.0 GPa, 500-800 °C, using the technique of producing overgrowths on natural seed crystals. Electron microprobe analyses of overgrowths up to >100 µm wide have located the phase transition from clinozoisite to zoisite as a function of P-T-Xps and a miscibility gap in the clinozoisite solid solution. The experiments confirm a narrow, steep zoisite-clinozoisite two-phase loop in T-Xps section. Maximum and minimum iron contents in coexisting zoisite and clinozoisite are given by $X{ ps}{ zo} (max) = 1.9*10{ - 4} T+ 3.1*10{ - 2} P - 5.36*10{ - 2} and X{ ps}{ czo} (min) = (4.6 * 10{ - 4} - 4 * 10{ - 5} P)T + 3.82 * 10{ - 2} P - 8.76 * 10{ - 2} $ (P in GPa, T in °C). The iron-free end member reaction clinozoisite = zoisite has equilibrium temperatures of 185+/-50 °C at 0.5 GPa and 0+/-50 °C at 2.0 GPa, with ΔHr0=2.8+/-1.3 kJ/mol and ΔSr0=4.5+/-1.4 J/mol×K. At 0.5 GPa, two clinozoisite modifications exist, which have compositions of clinozoisite I 0.15 to 0.25 Xps and clinozoisite II >0.55 Xps. The upper thermal stability of clinozoisite I at 0.5 GPa lies slightly above 600 °C, whereas Fe-rich clinozoisite II is stable at 650 °C. The schematic phase relations between epidote minerals, grossular-andradite solid solutions and other phases in the system CaO-Al2O3-Fe2O3-SiO2-H2O are shown.

  10. Fluid compositions in equilibrium with silica-undersaturated magmas in the system Na2O-Al2O3-SiO2-H2O: clues to the composition of fenitizing fluids

    NASA Astrophysics Data System (ADS)

    Preston, Robin; Stevens, Gary; McCarthy, Terence

    2002-11-01

    Fenites result from alkali metasomatism of granitoid rocks associated with the intrusion of silica-undersaturated alkaline magmas, and are characterized by addition of alkalis, iron and magnesium, albitization, nephelinization, removal of silica and the formation of alkali pyroxenes and amphiboles. In an attempt to constrain the fluid compositions involved in this process, we have investigated the compositions of the fluids in equilibrium with a range silica-undersaturated alkaline magmas, in the model system Al2O3-Na2O-SiO2-H2O at 850 °C and 1 kbar. The starting compositions straddle the nepheline-albite join, and include both peralkaline and alkali-granitoid compositions. The quenched run products all contained a glass, representing the melt, as well as an aqueous fluid and a radial crystalline phase interpreted to be a fluid quench phase. Several of the glasses also contained albite, nepheline or quartz crystals. Fluid compositions in crystal-free experiments were calculated using a mass-balance approach that incorporated the composition of the glass, composition of starting materials and carefully determined masses of the different run product fractions, as well as that of the starting materials. Compositions plotting to the peralkaline side of the nepheline-albite join produced fluids that were highly enriched in dissolved solids (SiO2 + Al2O3 + Na2O, in the range 40-50 wt%). This substantial fractionation of the solid starting materials, between melt and fluid phase, results in reasonable resolution of the fluid compositions produced, despite significant uncertainties in the measured Na2O and H2O concentrations in the glasses. Model calculations indicate that the fluid compositions in equilibrium with the more SiO2 undersaturated melt compositions in this study are capable of converting a typical granodiorite to a nepheline syenite composition at fluid/rock ratios lower than 1:1. Albitization and the removal of quartz (in the form of soluble sodium

  11. Precise and accurate isotope fractionation factors (α17O, α18O and αD) for water and CaSO4·2H2O (gypsum)

    NASA Astrophysics Data System (ADS)

    Gázquez, Fernando; Evans, Nicholas P.; Hodell, David A.

    2017-02-01

    Gypsum (CaSO4·2H2O) is a hydrated mineral containing crystallization water, also known as gypsum hydration water (GHW). We determined isotope fractionation factors (α17O, α18O and αD) between GHW and free water of the mother solution in the temperature range from 3 °C to 55 °C at different salinities and precipitation rates. The hydrogen isotope fractionation factor (αDgypsum-water) increases by 0.0001 units per °C between 3 °C and 55 °C and salinities <150 g/L of NaCl. The αDgypsum-water is 0.9812 ± 0.0007 at 20 °C, which is in good agreement with previous estimates of 0.981 ± 0.001 at the same temperature. The α18Ogypsum-water slightly decreases with temperature by 0.00001 per °C, which is not significant over much of the temperature range considered for paleoclimate applications. Between 3 °C and 55 °C, α18Ogypsum-water averages 1.0035 ± 0.0002. This value is more precise than that reported previously (e.g. 1.0041 ± 0.0004 at 25 °C) and lower than the commonly accepted value of 1.004. We found that NaCl concentrations below 150 g/L do not significantly affect α18Ogypsum-water, but αDgypsum-water increases linearly with NaCl concentrations even at relatively low salinities, suggesting a salt correction is necessary for gypsum formed from brines. Unlike oxygen isotopes, the αDgypsum-water is affected by kinetic effects that increase with gypsum precipitation rate. As expected, the relationship of the fractionation factors for 17O and 18O follows the theoretical mass-dependent fractionation on Earth (θ = 0.529 ± 0.001). We provide specific examples of the importance of using the revised fractionation factors when calculating the isotopic composition of the fluids.

  12. 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.; 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

  13. Experimental determination of REE fractionation between liquid and vapour in the systems NaCl-H2O and CaCl2-H2O up to 450 °C

    NASA Astrophysics Data System (ADS)

    Shmulovich, Kirill; Heinrich, Wilhelm; Möller, Peter; Dulski, Peter

    2002-09-01

    Fractionation of selected REE between brine and vapour was experimentally determined using a large-volume rocking Ti-autoclave that allowed quasi-isobaric sampling of liquid-vapour pairs. Samples were extracted along the 350, 400 and 450 °C-isotherms of the H2O-NaCl system, and along the 400 °C isotherm of the CaCl2 system. Total salt concentrations were either 6.6 and 10 wt% NaCl or CaCl2, respectively, and total REE concentrations were about 2 ppm of each REE. Starting pH at room temperature was 1.8, added as HCl. In another series of experiments, REEs were added in amounts of 312 ppm. Here, the starting pH at room temperature was 0.5, added as HNO3:HCl=1:2. Liquid-vapour pairs (L-V) were analysed for REE by ICP-MS methods. L-V-partitioning of REE along a particular isotherm follows broadly the partitioning of the main salt components, NaCl or CaCl2. DREE=REEV/REEL decrease rapidly from the critical point with decreasing pressure (equivalent to increasing salinity of the liquid) as the solvus opens. This is independent of the total amount of the added REE. Log DREE values show approximately linear correlations with decreasing pressure from the critical point to salt-saturated conditions where the L-V curve meets the liquid + vapour + solid boundary. At given P and T, we found a systematic variation of DREE along the La-Lu suite. HREE are enriched in the vapour phase relative to LREE. Fractionation coefficients KD=(HREEV/HREEL)/(LREEV/LREEL) increase linearly with ΔP=Pcrit-P along a particular isotherm. At the 450 °C isotherm, KD (Lu/La) at the critical point (425 bar and 10 wt% NaCl) is 1; about 2.5 at 350 bar (33 wt% NaCl in the liquid); and about 5 if extrapolated to salt-saturation (250 bar and 52 wt% NaCl in the liquid). The REE fractionation behaviour is similar along the CaCl2-H2O solvus boundaries. Existing equations of state and thermodynamic databases of REE species cannot predict this behaviour at L-V-equilibrium conditions. That HREE are

  14. 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.

    2016-12-01

    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), 2 V meas. = 60(5)°, 2 V 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

  15. Copper diphosphonates with zero-, one- and two-dimensional structures: ferrimagnetism in layer compound Cu3(ImhedpH)(2).2H2O [ImhedpH4=(1-C3H3N2)CH2C(OH)(PO3H2)2].

    PubMed

    Cao, Deng-Ke; Xie, Xiao-Ji; Li, Yi-Zhi; Zheng, Li-Min

    2008-10-07

    Reactions of CuSO4 with 2-(1-imidazole)-1-hydroxy-1,1'-ethylidenediphosphonic acid (ImhedpH4) under hydrothermal conditions at different temperatures lead to four new metal phosphonates: Cu(ImhedpH3)2(H2O).2H2O (), Cu(ImhedpH3)2 (), Cu3(ImhedpH2)2(ImhedpH3)(2).4H2O (), and Cu3(ImhedpH)(2).2H2O (). Compounds and have mononuclear structures in which the Cu atoms adopt square pyramidal and square planar geometries, respectively. In compound , a chain structure is observed where the Cu3(ImhedpH2)2(ImhedpH3)2 trimer units are connected by edge-sharing of the {Cu2O5} square pyramids. Compound exhibits a layer structure made up of Cu3(ImhedpH)2 trimer units. The connection of trimers through corner-sharing of {Cu1O4} and {CPO3} tetrahedra results in a two-dimensional layer containing 8- and 16-membered rings. The imidazole groups are grafted on the two sides of the layer. Magnetic studies reveal that ferromagnetic interactions are mediated in , while for compound , ferrimagnetism is observed below 5.8 K.

  16. Excision of uranium oxide chains and ribbons in the novel one-dimensional uranyl iodates K(2)[(UO(2))3(IO(3))(4)O(2)] and Ba[(UO(2)2(IO(3))(2)O(2)](H(2)O).

    PubMed

    Bean, A C; Ruf, M; Albrecht-Schmitt, T E

    2001-07-30

    The alkali metal and alkaline-earth metal uranyl iodates K(2)[(UO(2))(3)(IO(3))(4)O(2)] and Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) have been prepared from the hydrothermal reactions of KCl or BaCl(2) with UO(3) and I(2)O(5) at 425 and 180 degrees C, respectively. While K(2)[(UO(2))(3)(IO(3))(4)O(2)] can be synthesized under both mild and supercritical conditions, the yield increases from <5% to 73% as the temperature is raised from 180 to 425 degrees C. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), however, has only been isolated from reactions performed in the mild temperature regime. Thermal measurements (DSC) indicate that K(2)[(UO(2))(3)(IO(3))(4)O(2)] is more stable than Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) and that both compounds decompose through thermal disproportionation at 579 and 575 degrees C, respectively. The difference in the thermal behavior of these compounds provides a basis for the divergence of their preparation temperatures. The structure of K(2)[(UO(2))(3)(IO(3))(4)O(2)] is composed of [(UO(2))(3)(IO(3))(4)O(2)](2)(-) chains built from the edge-sharing UO(7) pentagonal bipyramids and UO(6) octahedra. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) consists of one-dimensional [(UO(2))(2)(IO(3))(2)O(2)](2)(-) ribbons formed from the edge sharing of distorted UO(7) pentagonal bipyramids. In both compounds the iodate groups occur in both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The K(+) or Ba(2+) cations separate the chains or ribbons in these compounds forming bonds with terminal oxygen atoms from the iodate ligands. Crystallographic data: K(2)[(UO(2))(3)(IO(3))(4)O(2)], triclinic, space group P_1, a = 7.0372(5) A, b = 7.7727(5) A, c = 8.9851(6) A, alpha = 93.386(1) degrees, beta = 105.668(1) degrees, gamma = 91.339(1) degrees, Z = 1; Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), monoclinic, space group P2(1)/c, a = 8.062(4) A, b = 6.940(3) A, c = 21.67(1), beta= 98.05(1) degrees, Z = 4.

  17. 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.

  18. 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.

  19. Reversible shuttle action upon dehydration and rehydration processes in cationic coordinatively-bonded (4,4) square-grid nets threaded by supramolecular bonded anions, {[Cu(II)(4,4'-bpy)2(H2O)][Cu(II)(2-pySO3)3](NO3)}·H2O.

    PubMed

    Jiang, Yi-Min; Yin, Zheng; He, Kun-Huan; Zeng, Ming-Hua; Kurmoo, Mohamedally

    2011-03-21

    {[Cu(II)(4,4'-bpy)(2)(H(2)O)][Cu(II)(2-pySO(3))(3)](NO(3))}·H(2)O, obtained serendipitously by the reaction of the constituents in water, consists of parallel coordinatively bonded cationic (4,4) corrugated square-grids polymer of {[Cu(II)(4,4'-bpy)(2)(H(2)O)](2+)}(n) threaded by π-π and H-bonded supramolecular chains of [Cu(II)(2-pySO(3))(3)](-) through the open squares. A single-crystal to single-crystal transformation takes place upon removal of the noncoordinated water by controlled heating. The resulting structure exhibits a rearrangement of the coordination of the copper atoms in the grids, where the Cu-H(2)O bond is elongated from 2.250(3) to 2.628(3) Å while the Cu-NO(3) is shortened from 3.122(3) to 2.796(1) Å. This process is reversible as demonstrated by the single crystal structure after rehydration with corresponding bond distances of 2.224(3) and 3.152(3) Å. Such a cooperative effect may be associated with the Jahn-Teller distortion of the copper(II) ion accompanying the shuttle action of the hydrogen-bonded water and nitrate moiety.

  20. Microcrystalline phase transformation from ZrF4·HF·2H2O to ZrO2 through the intermediate phases ZrF4·3H2O, ZrF4·H2O, Zr2OF6·H2O and ZrF4

    NASA Astrophysics Data System (ADS)

    Dey, C. C.

    2014-09-01

    The behavior of hydrated zirconium fluoride has been studied by perturbed angular correlation spectroscopy. It is found that the crystalline compound ZrF4·HF·2H2O, formed initially by drying solution of Zr metal in concentrated HF, transforms spontaneously to ZrF4·3H2O. This trihydrated compound dehydrates to ZrF4 through the intermediate monohydrates ZrF4·H2O and Zr2OF6·H2O. The compound ZrF4 finally transforms to ZrO2 at ∼343 K. Different crystalline phases of ZrF4·HF·2H2O, ZrF4·3H2O, ZrF4·H2O, Zr2OF6·H2O, ZrF4 and ZrO2 have been identified and characterized by PAC spectroscopy. From previous PAC measurements, the intermediate ZrF4·H2O and Zr2OF6·H2O were not observed and the dehydration from ZrF4·3H2O to ZrF4 was found to be routed directly. Present measurements by PAC exhibits dissimilar crystal structures for ZrF4·3H2O and ZrF4·H2O unlike the crystal structures found in hafnium analogous compounds.

  1. Synthesis, structure and electrochemical properties of metal malonate Na2M(H2C3O4)2·nH2O (n = 0, 2) compounds and comparison with oxalate Na2M2(C2O4)3·2H2O compounds

    NASA Astrophysics Data System (ADS)

    Ahouari, H.; Rousse, G.; Klein, Y.; Chotard, J.-N.; Sougrati, M. T.; Recham, N.; Tarascon, J.-M.

    2015-04-01

    Oxalate and malonate based compounds were prepared by hydrothermal method. The crystal structure of oxalate compounds of formulae Na2M2(C2O4)3·2H2O (with M = Mn, Fe, Co, Ni and Mg) was confirmed from single crystal diffraction. We report here a series of new malonate compounds Na2M(H2C3O4)2·2H2O with M = Mn, Fe, Co, Ni, Zn and Mg, whose structure, thermal and electrochemical performances are presented. Metal malonate compounds crystallize in an orthorhombic structure built upon MO6 octahedra connected with malonate groups to form a layered structure. The removal/uptake of water from the malonate members was found to be reversible and the crystal structure of the anhydrous Na2Mn(H2C3O4)2 is solved from powder diffraction and presents similarities with the hydrated phase. However, sodium 3d-metal oxalates/malonates compounds show poor electrochemical activity.

  2. Molybdenum(VI) coordination chemistry of the N,N-disubstituted bis(hydroxylamido)-1,3,5-triazine ligand, H2bihyat. Water-assisted activation of the Mo(VI)═O bond and reversible dimerization of cis-[Mo(VI)O2(bihyat)] to [Mo(VI)2O4(bihyat)2(H2O)2].

    PubMed

    Stylianou, Marios; Nikolakis, Vladimiros A; Chilas, George I; Jakusch, Tamas; Vaimakis, Tiverios; Kiss, Tamas; Sigalas, Michael P; Keramidas, Anastasios D; Kabanos, Themistoklis A

    2012-12-17

    Reaction of the N,N-disubstituted bis(hydroxylamino) ligand 2,6-bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine (H(2)bihyat) with cis-[Mo(VI)O(2)(acac)(2)] in tetrahydrofuran resulted in isolation of the mononuclear compound cis-[Mo(VI)O(2)(bihyat)] (1). The treatment of Na(2)Mo(VI)O(4)·2H(2)O with the ligand H(2)bihyat in aqueous solution gave the dinuclear compounds cis-[Mo(VI)(2)O(4)(bihyat)(2)(H(2)O)(2)] (2) and trans-[Mo(VI)(2)O(4)(bihyat)(2)(H(2)O)(2)] (3) at pH values of 3.5 and 5.5, respectively. The structures for the three molybdenum(VI) compounds were determined by X-ray crystallography. Compound 1 has a square-pyramidal arrangement around molybdenum, while in the two dinuclear compounds, each molybdenum atom is in a distorted pentagonal-bipyramidal environment of two bridging and one terminal oxido groups, a tridentate (O,N,O) bihyat(2-) ligand that forms two five-membered chelate rings, and a water molecule trans to the terminal oxido group. The dinuclear compounds constitute rare examples containing the {Mo(2)(VI)O(2)(μ(2)-O(2))}(4+) moiety. The potentiometry revealed that the Mo(VI)bihyat(2-) species exhibit high hydrolytic stability in aqueous solution at a narrow range of pH values, 3-5. A subtle change in the coordination environment of the five-coordinate compound 1 with ligation of a weakly bound water molecule trans to the oxido ligand (1w) renders the equatorial oxido group in 1w more nucleophilic than that in 1, and this oxido group attacks a molybdenum atom and thus the dinuclear compounds 2 and 3 are formed. This process might be considered as the first step of the oxido group nucleophilic attack on organic substrates, resulting in oxidation of the substrate, in the active site of molybdenum enzymes such as xanthine oxidase. Theoretical calculations in the gas phase were performed to examine the influence of water on the dimerization process (1 → 2/3). In addition, the molecular structures, cis/trans geometrical isomerism for the

  3. 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.

  4. Synthesis, spectral characterizations and biological studies of transition metal mixed ligand complexes: X-ray crystal structures of [Cu(oda)(Bipy)(H 2O)]·4H 2O and [VO(oda)(Bipy)]·2H 2O

    NASA Astrophysics Data System (ADS)

    Siddiqi, Zafar A.; Sharma, Prashant K.; Shahid, M.; Khalid, Mohd.; Kumar, Sarvendra

    2011-05-01

    The ternary complexes of stoichiometries [M(oda)(Bipy)H 2O]· xH 2O [M = Cu ( 1), x = 4; Co ( 2), x = 2; Ni ( 3), x = 4 or Cr ( 4), x = 3] and [VO(oda)(Bipy)]·2H 2O ( 5), where H 2oda = oxydiacetic acid and Bipy = 2,2'-bipyridine, were prepared and characterized employing elemental, FAB-Mass, FT-IR, EPR, 1H and 13C NMR spectroscopic analyses. X-ray crystallography of ( 1) and ( 5) indicated a six coordinate distorted geometry. The antimicrobial activities of the complexes were investigated against Escherichia coli(k-12), Bacillus subtilis (MTC-121), Staphylococcus aureus (IOASA-22), Salmonella typhymurium (MTCC-98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei. The superoxide dismutase (SOD) mimic activity of the Cu(II) complex ( 1) was assessed employing NBT assay.

  5. Syntheses and structures of two new M 6L i8(N 3) a6 cluster-unit based compounds: Cs 4Re 6S 8(N 3) 6·H 2O and Na 2Mo 6Br 8(N 3) 6·2H 2O

    NASA Astrophysics Data System (ADS)

    Pilet, Guillaume; Cordier, Stéphane; Golhen, Stéphane; Perrin, Christiane; Ouahab, Lahcène; Perrin, André

    2003-09-01

    The two new cluster compounds, Cs 4Re 6S 8(N 3) 6·H 2O (1) and Na 2Mo 6Br 8(N 3) 6·2H 2O (2), have been prepared via solution chemistry route, starting from the Cs 4Re 6S 8Br 6CsBr and Mo 6Br 12 precursors synthesized by solid state chemistry techniques, and structurally characterized (crystal data: Cs 4Re 6S 8(N 3) 6·H 2O (1): Orthorhombic, space group Pnam, a=10.0651(1) Å, b=15.8856(2) Å, c=20.1714(3) Å, V=3225.2(7) Å 3, Z=4, dcalc=4.48 g cm -3, μ=27.43 mm -1; Na 2Mo 6Br 8(N 3) 6·2H 2O (2): Orthorhombic, space group Ibam, a=11.5643(3) Å, b=14.3959(5) Å, c=17.0340(7) Å, V=2835.8(2) Å 3, Z=4, dcalc=3.63 g cm -3, μ=13.91 mm -1). Their structures revealed that in both cases, the M 6L i8 cluster core remains unchanged in the starting and final compounds whereas the bromine apical ligands (Br a) are substituted by N 3 azide groups leading to M 6L i8(N 3) a6 cluster unit. The new Cs 4Re 6S 8(N 3) 6·H 2O is the first example of a compound containing an octahedral rhenium cluster coordinated to azide groups.

  6. Variable dimensionality and framework found in a series of quaternary zinc selenites, A2Zn3(SeO3)4·xH2O (A = Na, Rb, and Cs; 0≤x≤1) and Cs2Zn2(SeO3)3·2H2O

    NASA Astrophysics Data System (ADS)

    Lü, Minfeng; Jo, Hongil; Oh, Seung-Jin; Ok, Kang Min

    2017-01-01

    Five new alkali metal zinc selenites, A2Zn3(SeO3)4·xH2O (A = Na, Rb, and Cs; 0≤x≤1) and Cs2Zn2(SeO3)3·2H2O have been synthesized by heating a mixture of ZnO, SeO2 and A2CO3 (A = Na, Rb, and Cs), and characterized by X-ray diffraction (XRD) and spectroscopic analyses techniques. All of the reported materials revealed a rich structural chemistry with different frameworks and connection modes of Zn2+. While Rb2Zn3(SeO3)4 and Cs2Zn3(SeO3)4·H2O revealed three-dimensional frameworks consisting of isolated ZnO4 tetrahedra and SeO3 polyhedra, Na2Zn3(SeO3)4, Cs2Zn3(SeO3)4, and Cs2Zn2(SeO3)3·2H2O contained two-dimensional [Zn3(SeO3)4]2- layers. Specifically, whereas isolated ZnO4 tetrahedra and SeO3 polyhedra are arranged into two-dimensional [Zn3(SeO3)4]2- layers in two cesium compounds, circular [Zn3O10]14- chains and SeO3 linkers are formed in two-dimensional [Zn3(SeO3)4]2- layers in Na2Zn3(SeO3)4. Close structural examinations suggest that the size of alkali metal is significant in determining the framework geometry as well as connection modes of transition metal cations.

  7. Probing the Self-Assembly Mechanism of Lanthanide-Containing Sandwich-Type Silicotungstates [{Ln(H2O)n}2{Mn4(B-α-SiW9O34)2(H2O)2}](6-) Using Time-Resolved Mass Spectrometry and X-ray Crystallography.

    PubMed

    Fan, Lin-Yuan; Lin, Zheng-Guo; Cao, Jie; Hu, Chang-Wen

    2016-03-21

    The reaction of [γ-SiW10O36](8-) with Mn(2+) and Ln(3+) in an aqueous solution led to the isolation of a series of new lanthanide-containing sandwich-type polyoxometalates (POMs) [{Ln(H2O)n}2{Mn4(B-α-SiW9O34)2(H2O)2}](6-) (1-5a) (Ln = La (1), Nd (2), Gd (3), Dy (4), Er (5); n = 5, 6), which crystallize in the space groups C2/c with a = 33.0900(2)-32.9838(15) Å, b = 12.8044(10)-12.7526(6) Å, c = 22.8273(17)-22.6368(11) Å, V = 9669.2(12)-9519.7(8) Å(3), Z = 2 (1, 2); P1̅ with a = 11.9502(4)-11.8447(6) Å, b = 13.2203(4)-13.1164(5) Å, c = 15.8291(5)-15.8524(7) Å, V = 2221.25(13)-2189.95(18) Å(3), Z = 1 (3, 4, 5), respectively. X-ray diffraction analysis reveals that they consist of two-dimensional networks based on a sandwich-type polyanion [Mn4(B-α-SiW9O34)2(H2O)2](12-) (6a, {Mn4(SiW9)2}) and lanthanide cations (Ln(3+)), which are further connected into three-dimensional frameworks by potassium cations for 3, 4, and 5. The unprecedented combination of time-resolved electrospray ionization mass spectrometry (ESI-MS) studies and X-ray crystallography allows us not only to directly observe the in-solution rearrangement of divant anion [γ-SiW10O36](8-) into the sandwich-type POM 6a via an intermediate species [Mn3(B-β-SiW8O30(OH))(B-β-SiW9O33(OH))(H2O)](12-) (7a, {Mn3(SiW8)(SiW9)}) from ESI-MS results, but also to gain the solid-state structures of intermediate and final product isolated from reaction solutions from X-ray crystallography results, from which the self-assembly mechanism of the lanthanide-containing sandwich-type POMs 1-5a was proposed.

  8. 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.

  9. Chelation of UO(2)(2+) by vitamin B6 complex derivatives: synthesis and characterization of [UO2(beta-pyracinide)2(H2O)] and [UO2(Pyr2en)DMSO]Cl2{Pyr2en=N,N'-ethylenebis(pyridoxylideneiminato)}. A useful modeling of assimilation of uranium by living beings.

    PubMed

    Back, Davi Fernando; de Oliveira, Gelson Manzoni; Lang, Ernesto Schulz

    2006-10-01

    The vitamin B(6) derivatives 4-pyridoxic acid (anionic) and the Schiff base N,N'-ethylenebis(pyridoxylideneiminato) react with UO(2)(NO(3))(2) * 6H(2)O to give [UO(2)(beta-pyracinide)(2)(H(2)O)] (beta-pyracin=4-pyridoxic acid) and [UO(2)(Pyr(2)en)DMSO]Cl(2)(Pyr(2)en=N,N'-ethylenebis(pyridoxylideneiminato); DMSO=dimethyl sulfoxide). In both compounds the two uranyl oxo ligands set the axis of distorted pentagonal bipyramides. The ability of vitamin B(6) derivatives to react with UO(2)(2+) allowing the chelation of one uranium atom represents a very specific model of assimilation of uranium by living beings. It could also explain the serious damages caused by heavy or radioactive metals like uranium since their complexation "in vivo" by enzymatic systems like pyridoxal phosphate-containing enzymes would lead to a modification of the prosthetic groups of the metalloenzymes with loss of their catalytic activities.

  10. 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

  11. High-throughput and in situ EDXRD investigation on the formation of two new metal aminoethylphosphonates - Ca(O3PC2H4NH2) and Ca(OH)(O3PC2H4NH3)·2H2O

    NASA Astrophysics Data System (ADS)

    Schmidt, Corinna; Feyand, Mark; Rothkirch, André; Stock, Norbert

    2012-04-01

    The system Ca2+/2-aminoethylphosphonic acid/H2O/NaOH was systematically investigated using high-throughput methods. The experiments led to one new compound Ca(O3PC2 H4NH2) (1) and the crystal structure was determined using in house X-ray powder diffraction data (monoclinic, P21/c, a=9.7753(3), b=6.4931(2), c=8.4473(2) Å, β=106.46(2)°, V=514.20(2) Å3, Z=4). The formation of 1 was investigated by in situ energy dispersive X-ray diffraction measurements (EDXRD) at beamline F3 at HASYLAB (light source DORIS III), DESY, Hamburg. An intermediate, Ca(OH)(O3PC2H4NH3)·2H2O (2), was observed and could be isolated from the reaction mixture at ambient temperatures by quenching the reaction. The crystal structure of 2 was determined from XRPD data using synchrotron radiation (monoclinic, P21/m, a=11.2193(7), b=7.1488(3), c=5.0635(2) Å, β=100.13(4)°, V=399.78(3) Å3, Z=2).

  12. 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.

  13. 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.

  14. Racemic monoperoxovanadium(V) complexes with achiral OO and ON donor set heteroligands: synthesis, crystal structure and stereochemistry of [NH3(CH2)2NH3][VO(O2)(ox)(pic)].2H2O and [NH3(CH2)2NH3][VO(O2)(ox)(pca)].

    PubMed

    Tatiersky, Jozef; Schwendt, Peter; Sivák, Michal; Marek, Jaromír

    2005-07-07

    Monoperoxovanadium(V) complexes, [NH3(CH2)2NH3][VO(O2)(ox)(pic)].2H2O (1) and [NH3(CH2)2NH3][VO(O2)(ox)(pca)] (2) [NH3(CH2)2NH3 = ethane-1,2-diammonium(2+), ox=oxalate(2-), pic=pyridine-2-carboxylate(1-), pca=pyrazine-2-carboxylate(1-)], were synthesized and characterized by X-ray analysis, IR and Raman spectroscopies. The five equatorial positions of the pentagonal bipyramid around the vanadium atoms are occupied by the eta2-peroxo ligand, two oxygen atoms of the ox, and the nitrogen atom of the pic or pca ligands, respectively. The oxo ligand and the oxygen atom of pic or pca are in the axial positions. Networks of X-HO (X=C, N or O) hydrogen bonds, and pi-pi interactions between aromatic rings in and anion-pi interactions in , determine the molecular packings and build up the supramolecular architecture. Three stereochemical rules for occupation of the donor sites in two-heteroligand [VO(O2)(L1)(L2)] complexes (L1, L2 are bidentate neutral or differently charged anionic heteroligands providing an OO, NN or ON donor set) are discussed. and crystallize as racemic compounds. The 51V NMR spectra proved that the parent complex anions of and partially decompose on dissolution in water to the monoperoxo-ox, -pic or -pca complexes.

  15. 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.

  16. 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.

  17. Phase relations in the greenschist-blueschist-amphibolite-eclogite facies in the system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O (NCFMASH), with application to metamorphic rocks from Samos, Greece

    NASA Astrophysics Data System (ADS)

    Will, Thomas; Okrusch, Martin; Schmädicke, Esther; Chen, Guoli

    Calculated phase equilibria among the minerals sodic amphibole, calcic amphibole, garnet, chloritoid, talc, chlorite, paragonite, margarite, omphacite, plagioclase, carpholite, zoisite/clinozoisite, lawsonite, pyrophyllite, kyanite, sillimanite, quartz and H2O are presented for the model system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O (NCFMASH), which is relevant for many greenschist, blueschist, amphibolite and eclogite facies rocks. Using the activity-composition relationships for multicomponent amphiboles constrained by Will and Powell (1992), equilibria containing coexisting calcic and sodic amphiboles could be determined. The blueschist-greenschist transition reaction in the NCFMASH system, for example, is defined by the univariant reaction sodic amphibole + zoisite=calcic amphibole + chlorite + paragonite + plagioclase (+ quartz + H2O) occurring between approximately 420 and 450°C at 9.5 to 10kbar. The calculated petrogenetic grid is a valuable tool for reconstructing the PT-evolution of metabasic rocks. This is shown for rocks from the island of Samos, Greece. On the basis of mineral and whole rock analyses, PT-pseudosections were calculated and, together with the observed mineral assemblages and reaction textures, are used to reconstruct PT-paths. For rocks from northern Samos, pseudomorphs after lawsonite preserved in garnet, the assemblage sodic amphibole-garnet-paragonite-chlorite-zoisite-quartz and the retrograde appearance of albitic plagioclase and the formation of calcic amphibole around sodic amphibole constrain a clockwise PT-path that reaches its thermal maximum at some 520°C and 19kbar. The derived PT-trajectory indicates cooling during exhumation of the rocks and is similar to paths for rocks from the western part of the Attic-Cycladic crystalline complex. Rocks from eastern Samos indicate lower pressures and are probably related to high-pressure rocks from the Menderes Massif in western Turkey.

  18. Further evidence for the tetraoxoiodate(V) anion, IO(4)(3-): hydrothermal syntheses and structures of Ba[(MoO(2))(6)(IO(4))(2)O(4)] x H(2)O and Ba(3)[(MoO(2))(2)(IO(6))(2)] x 2H(2)O.

    PubMed

    Sykora, Richard E; Wells, Daniel M; Albrecht-Schmitt, Thomas E

    2002-05-20

    The hydrothermal reaction of MoO(3) with BaH(3)IO(6) at 180 degrees C for 3 days results in the formation of Ba[(MoO(2))(6)(IO(4))(2)O(4)] x H(2)O (1). Under similar conditions, the reaction of Ba(OH)(2) x 8H(2)O with MoO(3) and Ba(IO(4))(2) x 6H(2)O yields Ba(3)[(MoO(2))(2)(IO(6))(2)] x 2H(2)O (2). The structure of 1, determined by single-crystal X-ray diffraction, consists of corner- and edge-sharing distorted MoO(6) octahedra that create two-dimensional slabs. Contained within this molybdenum oxide framework are approximately C(2v) tetraoxoiodate(V) anions, IO(4)(3-), that are involved in bonding with five Mo(VI) centers. The two equatorial oxygen atoms of the IO(4)(3-) anion chelate a single Mo(VI) center, whereas the axial atoms are mu(3)-oxo groups and complete the octahedra of four MoO(6) units. The coordination of the tetraoxoiodate(V) anion to these five highly electropositive centers is probably responsible for stabilizing the substantial anionic charge of this anion. The Ba(2+) cations separate the layers from one another and form long ionic contacts with neighboring oxygen atoms and a water molecule. Compound 2 also contains distorted MoO(6) octahedra. However, these solely edge-share with octahedral hexaoxoiodate(VII), IO(6)(5-), anions to form zigzagging one-dimensional, (1)(infinity)[(MoO(2))(IO(6))](3-), chains that are polar. These chains are separated from one another by Ba(2+) cations that are coordinated by additional water molecules. Bond valence sums for the iodine atoms in 1 and 2 are 5.01 and 7.03, respectively. Crystallographic data: 1, monoclinic, space group C2/c, a = 13.584(1) A, b = 7.3977(7) A, c = 20.736(2) A, beta = 108.244(2) degrees, Z = 4; 2, orthorhombic, space group Fdd2, a = 13.356(7) A, b = 45.54(2) A, c = 4.867(3) A, Z = 8.

  19. Cyclic polyvanadates incorporating template transition metal cationic species: synthesis and structures of hexavanadate [PdV6O18]4-, octavanadate [Cu2V8O24]4-, and decavanadate [Ni4V10O30(OH)2(H2O)6]4-.

    PubMed

    Kurata, Taisei; Uehara, Akira; Hayashi, Yoshihito; Isobe, Kiyoshi

    2005-04-04

    Three types of heteropolyvanadates, [(C2H5)4N]4[PdV6O18] (1), [(C2H5)4N]4[Cu2V8O24] (2), and [(C6H5)4P]4[Ni4V10O30(OH)2(H2O)6] (3), were synthesized through the reaction between the [VO3]- anion and metal template cations of Pd(II), Cu(II), and Ni(II). The X-ray crystal structures of 1 (a = 29.952(4) A, b = 12.911(2) A, and c = 13.678(2) A, orthorhombic, space group Pca2(1) with Z = 4), 2 (a = 13.740(1) A, b = 22.488(2) A, c = 18.505(2) A, and beta= 94.058(2) degrees , monoclinic, space group P2(1)/n with Z = 4), and 3 (a = 12.333(2) A, b = 16.208(4) A, c = 16.516(3) A, alpha = 112.438(3) degrees , beta = 94.735(3) degrees , and gamma = 104.749(3) degrees , triclinic, space group P with Z = 1) demonstrate that the metal cationic species induced cyclic [VO3](n-)n (n = 6, 8, 10) ring formation and the cations are incorporated in the rings themselves. In the metal inclusion products, the cyclic vanadates act as macrocyclic ligands, in which the metal cationic species act as the templates. The cyclic vanadate is composed of tetrahedral VO4 units that share corners and incorporates a metal cationic species in the center of the molecules. The bowl-shaped complex 1 includes a Pd2+ cation that is coordinated by the oxygen donors of a boatlike hexavanadate ring. The diamagnetic complex 1 was characterized via 51V and 17O NMR spectroscopy. Complex 2 involves an octavanadate ring and two Cu2+, which are located on both sides of the mean plane as defined by the eight oxygen atoms that bridge the vanadium atoms. In the case of complex 3, the di-mu-hydroxo-bridged Ni2+ dimer with capped Ni2+ aqua ions is formed by hydrolysis to form the decavanadate ring, in which two of the tetrahedral vanadate units are not bonded to the Ni2+ core but supported by hydrogen bonds through the aqua-ligand in the capped Ni2+ cation. Complexes 1-3 in solution were clearly identified by their characteristic isotope patterns using ESI-MS studies.

  20. Insights into the origin of cooperative effects in the spin transition of [Fe(NH2trz)3](NO3)2: the role of supramolecular interactions evidenced in the crystal structure of [Cu(NH2trz)3](NO3)2.H2O.

    PubMed

    Dîrtu, Marinela M; Neuhausen, Christine; Naik, Anil D; Rotaru, Aurelian; Spinu, Leonard; Garcia, Yann

    2010-06-21

    The thermally induced hysteretic spin transition (ST) that occurs in the polymeric chain compound [Fe(NH(2)trz)(3)](NO(3))(2) (1) above room temperature (T(c)(upward arrow) = 347 K, T(c)(downward arrow) = 314 K) has been tracked by (57)Fe Mössbauer spectroscopy, SQUID magnetometry, differential scanning calorimetry (DSC), and X-ray powder diffraction (XPRD) at variable temperatures. From the XRPD pattern indexation, an orthorhombic primitive cell was observed with the following cell parameters: a = 11.83(2) A, b = 9.72(1) A, c = 6.361(9) A at 298 K (low-spin state) and a = 14.37(2) A, b = 9.61(4) A, c = 6.76(4) A at 380 K (high-spin state). The enthalpy and entropy variation associated to the ST of 1, have been evaluated by DSC as DeltaH = 23(1) kJ mol(-1) and DeltaS = 69.6(1) J mol(-1) K(-1). These thermodynamic data were used within a two-level Ising like model for the statistical analysis of First Order Reversal Curve (FORC) diagram that was recorded for 1, in the cooling mode. Strong intramolecular cooperative effects are witnessed by the derived interaction parameter of J = 496 K. The crystal structure of [Cu(NH(2)trz)(3)](NO(3))(2).H(2)O (2) was obtained thanks to high quality single crystals prepared by slow evaporation after hydrothermal pretreatment. The catena poly[mu-tris(4-amino-1,2,4-triazole-N1,N2) copper(II)] dinitrate monohydrate (2) crystallizes in the monoclinic space group C2/c, with a = 16.635(6) A, b = 13.223(4) A, c = 7.805(3) A, beta = 102.56(3) degrees, Z = 4. Complex 2 is a 1D infinite chain containing triple N1,N2-1,2,4-triazole bridges with an intra-chain distance of Cu...Cu = 3.903(1) A. A dense H-bonding network with the nitrate counteranion involved in intra-chain and inter-chain interactions is observed. Such a supramolecular network could be at the origin of the unusually large hysteresis loop displayed by 1 (DeltaT approximately 33 K), as a result of an efficient propagation of elastic interactions through the network. This

  1. Molecular precursors for the preparation of homogenous zirconia-silica materials by hydrolytic sol-gel process in organic media. Crystal structures of [Zr{OSi(O(t)Bu)3}4(H2O)2]·2H2O and [Ti(O(t)Bu){OSi(O(t)Bu)3}3].

    PubMed

    Dhayal, Veena; Chaudhary, Archana; Choudhary, Banwari Lal; Nagar, Meena; Bohra, Rakesh; Mobin, Shaikh M; Mathur, Pradeep

    2012-08-21

    [Zr(OPr(i))(4)·Pr(i)OH] reacts with [HOSi(O(t)Bu)(3)] in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy zirconosiloxane precursors of the types [Zr(OPr(i))(3){OSi(O(t)Bu)(3)}] (A) and [Zr(OPr(i))(2){OSi(O(t)Bu)(3)}(2)] (B), respectively. Further reactions of A or B with glycols in 1:1 molar ratio afforded six chemically modified precursors of the types [Zr(OPr(i))(OGO){OSi(O(t)Bu)(3)}] (1A-3A) and [Zr(OGO){OSi(O(t)Bu)(3)}(2)] (1B-3B), respectively [where G = (-CH(2)-)(2) (1A, 1B); (-CH(2)-)(3) (2A, 2B) and (-CH(2)CH(2)CH(CH(3)-)} (3A, 3B)]. The precursors A and B are viscous liquids, which solidify on ageing whereas the other products are all solids, soluble in common organic solvents. These were characterized by elemental analyses, molecular weight measurements, FAB mass, FTIR, (1)H, (13)C and (29)Si-NMR studies. Cryoscopic molecular weight measurements of all the products, as well as the FAB mass studies of 3A and 3B, indicate their monomeric nature. However, FAB mass spectrum of the solidified B suggests that it exists in dimeric form. Single crystal structure analysis of [Zr{OSi(O(t)Bu)(3)}(4)(H(2)O)(2)]·2H(2)O (3b) (R(fac) = 11.9%) as well as that of corresponding better quality crystals of [Ti(O(t)Bu){OSi(O(t)Bu)(3)}(3)] (4) (R(fac) = 5.97%) indicate the presence of a M-O-Si bond. TG analyses of 3A, B, and 3B indicate the formation of zirconia-silica materials of the type ZrO(2)·SiO(2) from 3A and ZrO(2)·2SiO(2) from B or 3B at low decomposition temperatures (≤200 °C). The desired homogenous nano-sized zirconia-silica materials [ZrO(2)·nSiO(2)] have been obtained easily from the precursors A and B as well as from the glycol modified precursors 3A and 3B by hydrolytic sol-gel process in organic media without using any acid or base catalyst, and these were characterized by powder XRD patterns, SEM images, EDX analyses and IR spectroscopy.

  2. Crystal structures of two deca-vanadates(V) with penta-aqua-manganese(II) pendant groups: (NMe4)2[V10O28{Mn(H2O)5}2]·5H2O and [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O.

    PubMed

    Franco, Maurício P; Rüdiger, André Luis; Soares, Jaísa F; Nunes, Giovana G; Hughes, David L

    2015-02-01

    Two heterometallic deca-vanadate(V) compounds, bis-(tetra-methyl-ammonium) deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimang-anese(II)-deca-vanadate(V) penta-hydrate, (Me4N)2[V10O28{Mn(H2O)5}2]·5H2O, A, and bis-{[tris-(hy-droxy-meth-yl)meth-yl]ammonium} deca-aquadi-μ4-oxido-tetra-μ3-oxido-hexa-deca-μ2-oxido-hexa-oxidodimanganese(II)deca-vanadate(V) dihydrate, [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O, B, have been synthesized under mild reaction conditions in an aqueous medium. Both polyanions present two [Mn(OH2)5](2+) complex units bound to the deca-vanadate cluster through oxide bridges. In A, the deca-vanadate unit has 2/m symmetry, whereas in B it has twofold symmetry. Apart from this, the main differences between A and B rest on the organic cations, tetra-methyl-ammonium and [tris-(hy-droxy-meth-yl)meth-yl]ammonium, respectively, and on the number and arrangement of the water mol-ecules of crystallization. In both compounds, the H atoms from the coordinating water mol-ecules participate in extensive three-dimensional hydrogen-bonding networks, which link the cluster units both directly and through solvent mol-ecules and, in B, through the 'tris-' cation hydroxyl groups. The cation in B also participates in N-H⋯O hydrogen bonds. A number of C-H⋯O inter-actions are also observed in both structures.

  3. Crystal structures of two deca­vanadates(V) with penta­aqua­manganese(II) pendant groups: (NMe4)2[V10O28{Mn(H2O)5}2]·5H2O and [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O

    PubMed Central

    Franco, Maurício P.; Rüdiger, André Luis; Soares, Jaísa F.; Nunes, Giovana G.; Hughes, David L.

    2015-01-01

    Two heterometallic deca­vanadate(V) compounds, bis­(tetra­methyl­ammonium) deca­aquadi-μ4-oxido-tetra-μ3-oxido-hexa­deca-μ2-oxido-hexa­oxidodimang­anese(II)­deca­vanadate(V) penta­hydrate, (Me4N)2[V10O28{Mn(H2O)5}2]·5H2O, A, and bis­{[tris­(hy­droxy­meth­yl)meth­yl]ammonium} deca­aquadi-μ4-oxido-tetra-μ3-oxido-hexa­deca-μ2-oxido-hexa­oxidodimanganese(II)deca­vanadate(V) dihydrate, [NH3C(CH2OH)3]2[V10O28{Mn(H2O)5}2]·2H2O, B, have been synthesized under mild reaction conditions in an aqueous medium. Both polyanions present two [Mn(OH2)5]2+ complex units bound to the deca­vanadate cluster through oxide bridges. In A, the deca­vanadate unit has 2/m symmetry, whereas in B it has twofold symmetry. Apart from this, the main differences between A and B rest on the organic cations, tetra­methyl­ammonium and [tris­(hy­droxy­meth­yl)meth­yl]ammonium, respectively, and on the number and arrangement of the water mol­ecules of crystallization. In both compounds, the H atoms from the coordinating water mol­ecules participate in extensive three-dimensional hydrogen-bonding networks, which link the cluster units both directly and through solvent mol­ecules and, in B, through the ‘tris­’ cation hydroxyl groups. The cation in B also participates in N—H⋯O hydrogen bonds. A number of C—H⋯O inter­actions are also observed in both structures. PMID:25878804

  4. The FORMAMIDE_2-H_2O Complex: Structure and Hydrogen Bond Cooperative Effects

    NASA Astrophysics Data System (ADS)

    Blanco, Susana; Pinacho, Pablo; Lopez, Juan Carlos

    2016-06-01

    The adduct formamide_2-H_20 has been detected in a supersonic expansion and its rotational spectra in the 5-13 GHz frequency region characterized by narrow-band molecular beam Fourier transform microwave spectroscopy (MB-FTMW). The spectrum shows the hyperfine structure due to the presence of two 14N-nuclei. This hyperfine structure has been analyzed and the determined quadrupole coupling constants together with the rotational constants have been a key for the identification of the adduct structure on the light of ab initio computations. The rotational parameters are consistent with the formation of a three body cycle thanks to the double proton acceptor/proton donor character of both formamide and water. The low value of the planar moment of inertia Pcc indicates that the heavy atom skeleton of the cluster is essentially planar. A detailed analysis of the results reveals the subtle effects of hydrogen bond cooperative effects in this system.

  5. 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.

  6. Materials Data on K2P2H2O7 (SG:11) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-05

    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. Pressure dependence of the contact angle in a CO2-H2O-coal system.

    PubMed

    Siemons, Nikolai; Bruining, Hans; Castelijns, Hein; Wolf, Karl-Heinz

    2006-05-15

    Carbon dioxide injection into coal layers serves the dual purpose to enhance coal bed methane production (ECBM) and to store CO2. The efficiency of this process is expected to be much higher if water is the non-wetting phase in the coal-water-gas system. Therefore, contact angles in the coal-water-CO2 system have been measured using the captive bubble technique in the pressure range between atmospheric pressure and 141 bar at a temperature of 45 degrees C. At atmospheric pressure the contact angle of a shrinking CO2 droplet increases with time, but stays below 90 degrees . At higher pressures (>2.6 bar) the contact angle increases beyond 90 degrees . The pressure dependence of the contact can be represented by theta=(111 degrees +/-10.5 degrees )+(0.17+/-0.14)P [bar]. The exceptional behavior at atmospheric pressure is possibly related to the stability of water patches on the coal surface. It is concluded that water is the non-wetting phase in this coal-water-CO2 system.

  8. Materials Data on K2P2H2O7 (SG:2) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-04

    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

  9. The Volatile Contents (CO2, H2O, F, S, Cl) of the Lunar Picritic Glasses

    NASA Astrophysics Data System (ADS)

    Saal, A. E.; Hauri, E. H.; Rutherford, M. J.; Cooper, R. F.

    2007-03-01

    We present the first report of magmatic water in lunar basalts using the primitive lunar volcanic glasses from Apollo 15 and 17 landing sites. We complement the data with new data on Cl, F, S. Our new technique improve the detection limit for volatiles by

  10. LiBr. 2H(2)O Crystallization Inhibition in the Presence of Additives.

    PubMed

    Ring, Terry Arthur; Dirksen, James A.; Duvall, Kristin Nicole; Jongen, Nathalie

    2001-07-15

    Experiments have been performed to measure the effect of additives on the crystallization temperature of concentrated LiBr solutions cooled at a rate of 20 degrees C/h. The measured crystallization temperatures correspond not to the temperatures of equilibrium solubility but to the critical temperature for heterogeneous nucleation of the hydrated LiBr salt on the glass wall of the test tube containing the sample solution. Various additives at concentrations from 250 to 1500 ppm have been investigated. Some soluble additives further decreased the experimental crystallization temperature by as much as 13 degrees C, corresponding to 22 degrees C below the equilibrium solubility. Large decreases in the crystallization temperature can be correlated with large values of complexation constants of the additive for either the Li(+) or the Br(-) ion in solution. Solution complexation, however, is not sufficient to explain the magnitude of the decrease in the crystallization temperature. The only phenomenon capable of quantitatively explaining the magnitude of the decrease in the crystallization temperature is the change in the crystal/solution interfacial energy due to adsorption of the additive on the surface of the prenucleation embryos. A quantitative model of the crystal/solution interfacial energy due to adsorption has been developed using both the Langmuir and Gibbs adsorption equations, allowing the quantitative prediction of crystallization temperatures with additive concentration. Copyright 2001 Academic Press.

  11. Basalt-CO2-H2O Interactions and Variability in Carbonate Mineralization Rates

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.

    2009-02-01

    Flood basalts are receiving increasing attention as possible host formations for geologic sequestration of anthropogenic CO2, with studies underway in the U.S., India, Iceland, and Canada. Our previous laboratory studies with Columbia River basalts showed relative quick precipitation of carbonate minerals compared to other siliclastic rocks when batch reacted with water and supercritical CO2. In this study, our prior work with Columbia River basalt was extended to tests with basalts from the eastern U.S., India, and Africa. The basalts are all similar in bulk chemistry and share common minerals such as plagioclase, augite, and a glassy mesostasis. Single pass flow through dissolution experiments under dilute solution and mildly acidic conditions indicate similar cation release behavior among the basalt samples tested. Despite similar bulk chemistry and apparent dissolution kinetics, long-term static experiments with CO2 saturated water show significant differences in rates of mineralization as well as precipitate chemistry and morphology. For example, basalt from the Newark Basin in the U.S. is by far the most reactive of any basalt tested to date. Carbonate reaction products for the Newark Basin basalt were globular in form and contained significantly more Fe than the secondary carbonates that precipitated on the other basalt samples. Calcite grains with classic “dogtooth spar” morphology and trace cation substitution (Mg and Mn) were observed in post-reacted samples associated with the Columbia River basalts. Other basalts produced solid precipitates with compositions that varied chemically throughout the entire testing period. Polished cross sections of the reacted grains show precipitate overgrowths with irregular regions outlined by dark and bright layers indicative of zonations of different compositions. For example, SEM-EDX analysis across carbonate precipitates, which resulted from 854 days of reaction of the Central Atlantic Mafic Province (CAMP) basalt with CO2 saturated water showed distinct chemical regions. Composition of dark colored regions was dominated by a CaCO3 end-member composition, whereas the bright regions were chemically closer to an FeCO3. Chemical differences in the precipitates indicate changes in fluid chemistry unique to the dissolution behavior of each basalt sample reacted with CO2 saturated water.

  12. Mineralization of Basalts in the CO2-H2O-SO2-O2 System

    SciTech Connect

    Schaef, Herbert T.; Horner, Jacob A.; Owen, Antionette T.; Thompson, Christopher J.; Loring, John S.; McGrail, B. Peter

    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 1wt% sulfur dioxide (SO2) and 1wt% oxygen (O2) at reservoir conditions (~100 bar, 90°C) for 49 and 98 days. Gypsum (CaSO4) was a common precipitate, occurred early as elongated blades with striations, and served as substrates for other mineral products. Bimodal pulses of water released during dehydroxylation were key indicators along with X-ray diffraction for verifying the presences 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 700–400 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.

  13. 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.

  14. 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.

  15. Refractive index of air: 3. The roles of CO2, H2O, and refractivity virials.

    PubMed

    Ciddor, Philip E

    2002-04-20

    The author's recent studies of the refractive index of air are extended, and several assumptions made therein are further examined. It is shown that the alternative dispersion equations for CO2, which are due to Edlen [Metrologia 2, 71 (1966)] and Old et al. [J. Opt. Soc. Am. 61, 89 (1971)] result in differences of less than 2 x 10(-9) in the phase refractive index and less than 3 x 10(-9) in the group refractive index for current and predicted concentrations of CO2. However, because the dispersion equation given by Old et al. is consistent with experimental data in the near infrared, it is preferable to the equation used by Edlen, which is valid only in the ultraviolet and the visible. The classical measurement by Barrell and Sears [Philos. Trans. R. Soc. London Ser. A 238, 1 (1939)] on the refractivity of moist air is shown to have some procedural errors in addition to the one discussed by Birch and Downs [Metrologia 30, 155 (1993)]. It is shown that for normal atmospheric conditions the higher refractivity virial coefficients related to the Lorentz-Lorenz relation are adequately incorporated into the empirically determined first refractivity virial. As a guide to users the practical limits to the calculation of the refractive index of the atmosphere that result from the uncertainties in the measurement of the various atmospheric parameters are summarized.

  16. 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.

  17. 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.

  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. Electrochemical System Would Supply O2, H2O, N2, And H2

    NASA Technical Reports Server (NTRS)

    Walter, Richard T.; Van Buskirk, Paul D.

    1992-01-01

    Electrochemical system includes fuel cells that convert high-energy-density chemical propellants to atmospheric gases. System provides cooling, water, and electrical energy. Applicable to terrestrial enclosed environments, laboratories, chemical processing plants, or portable medical facilities.

  20. 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.

  1. 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.

  2. Varying rock responses as an indicator of changes in CO2-H2O fluid composition

    NASA Technical Reports Server (NTRS)

    Friend, C. R. L.

    1986-01-01

    The formation of the late Archean charnockite zone of southern India was ascribed to dehydration recrystallization due to an influx of CO2. Pressure temperature conditions for the metamorphism were calculated at about 750 C and 7.5 Kbar. The composition of the volatile species presently contained in fluid inclusions in the rocks changes across the transition zone. The transition zone was studied at Kabbaldurga and the paths taken by the fluids were identified.

  3. [Fe(bipy)(CN)(4)](-) as a versatile building block for the design of heterometallic systems: synthesis, crystal structure, and magnetic properties of PPh(4)[Fe(III)(bipy)(CN)(4)] x H(2)O, [[Fe(III)(bipy)(CN)(4)](2)M(II)(H(2)O)(4)] x 4H(2)O, and [[Fe(III)(bipy)(CN)(4)](2)Zn(II)] x 2H(2)O [bipy = 2,2'-Bipyridine; M = Mn and Zn].

    PubMed

    Lescouëzec, Rodrigue; Lloret, Francesc; Julve, Miguel; Vaissermann, Jacqueline; Verdaguer, Michel

    2002-02-25

    The new cyano complexes of formulas PPh(4)[Fe(III)(bipy)(CN)(4)] x H(2)O (1), [[Fe(III)(bipy)(CN)(4)](2)M(II)(H(2)O)(4)] x 4H(2)O with M = Mn (2) and Zn (3), and [[Fe(III)(bipy)(CN)(4)](2)Zn(II)] x 2H(2)O (4) [bipy = 2,2'-bipyridine and PPh(4) = tetraphenylphosphonium cation] have been synthesized and structurally characterized. The structure of complex 1 is made up of mononuclear [Fe(bipy)(CN)(4)](-) anions, tetraphenyphosphonium cations, and water molecules of crystallization. The iron(III) is hexacoordinated with two nitrogen atoms of a chelating bipy and four carbon atoms of four terminal cyanide groups, building a distorted octahedron around the metal atom. The structure of complexes 2 and 3 consists of neutral centrosymmetric [[Fe(III)(bipy)(CN)(4)](2)M(II)(H(2)O)(4)] heterotrinuclear units and crystallization water molecules. The [Fe(bipy)(CN)(4)](-) entity of 1 is present in 2 and 3 acting as a monodentate ligand toward M(H(2)O)(4) units [M = Mn(II) (2) and Zn(II) (3)] through one cyanide group, the other three cyanides remaining terminal. Four water molecules and two cyanide nitrogen atoms from two [Fe(bipy)(CN)(4)](-) units in trans positions build a distorted octahedron surrounding Mn(II) (2) and Zn(II) (3). The structure of the [Fe(phen)(CN)(4)](-) complex ligand in 2 and 3 is close to that of the one in 1. The intramolecular Fe-M distances are 5.126(1) and 5.018(1) A in 2 and 3, respectively. 4 exhibits a neutral one-dimensional polymeric structure containing two types of [Fe(bipy)(CN)(4)](-) units acting as bismonodentate (Fe(1)) and trismonodentate (Fe(2)) ligands versus the divalent zinc cations through two cis-cyanide (Fe(1)) and three fac-cyanide (Fe(2)) groups. The environment of the iron atoms in 4 is distorted octahedral as in 1-3, whereas the zinc atom is pentacoordinated with five cyanide nitrogen atoms, describing a very distorted square pyramid. The iron-zinc separations across the single bridging cyanides are 5.013(1) and 5.142(1) A at Fe

  4. Interstratified composite of the anionic clays, Zn5(OH)8(NO3)2•2H2O and Ni3Zn2(OH)8(NO3)2•2H2O, by delamination-costacking

    NASA Astrophysics Data System (ADS)

    Nityashree, N.; Rajamathi, Michael

    2013-08-01

    The anionic clays zinc hydroxysalt and nickel zinc hydroxy double salt were delaminated in 1-butanol to get monolayer dispersions after interlayer modification with surfactant anion, dodecyl sulfate. When these dispersions were mixed and the mixture treated with excess of acetone, layers from the two clays co-stacked to give a composite in which the layers from the two clays were interstratified. The surfactant anion of the composite could be exchanged with nitrate ions. The nitrate intercalated composite showed increased thermal stability compared to zinc hydroxynitrate. In addition the composite showed improved alkali resistance. When treated with alkaline solution the zinc hydroxysalt layers partially dissolved leading to the formation of a zincate intercalated anionic clay composite.

  5. PVTx properties of the CO2-H2O and CO2-H2O-NaCl systems below 647 K: assessment of experimental data and thermodynamic models

    USGS Publications Warehouse

    Hu, Jiawen; Duan, Zhenhao; Zhu, Chen; Chou, I.-Ming

    2007-01-01

    Evaluation of CO2 sequestration in formation brine or in seawater needs highly accurate experimental data or models of pressure–volume–temperature-composition (PVTx) properties for the CO2–H2O and CO2–H2O–NaCl systems. This paper presents a comprehensive review of the experimental PVTx properties and the thermodynamic models of these two systems. The following conclusions are drawn from the review: (1) About two-thirds of experimental data are consistent with each other, where the uncertainty in liquid volumes is within 0.5%, and that in gas volumes within 2%. However, this accuracy is not sufficient for assessing CO2 sequestration. Among the data sets for liquids, only a few are available for accurate modeling of CO2 sequestration. These data have an error of about 0.1% on average, roughly covering from 273 to 642 K and from 1 to 35 MPa; (2) There is a shortage of volumetric data of saturated vapor phase. (3) There are only a few data sets for the ternary liquids, and they are inconsistent with each other, where only a couple of data sets can be used to test a predictive density model for CO2 sequestration; (4) Although there are a few models with accuracy close to that of experiments, none of them is accurate enough for CO2 sequestration modeling, which normally needs an accuracy of density better than 0.1%. Some calculations are made available on www.geochem-model.org.

  6. Materials Data on Ca2MgP2(H2O5)2 (SG:2) 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

  7. Materials Data on Ca2MnP2(H2O5)2 (SG:2) 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

  8. Materials Data on K2MgCr2(H2O5)2 (SG:2) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-02-04

    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

  9. Materials Data on Zn3P2(H2O3)4 (SG:62) 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

  10. Inverse modeling of seasonal drought effects on canopy CO2/H2O exchange in three Mediterranean ecosystems

    NASA Astrophysics Data System (ADS)

    Reichstein, Markus; Tenhunen, John; Roupsard, Olivier; Ourcival, Jean-Marc; Rambal, Serge; Miglietta, Franco; Peressotti, Alessandro; Pecchiari, Marco; Tirone, Giampiero; Valentini, Riccardo

    2003-12-01

    We present a two-criteria inverse modeling approach to analyze the effects of seasonal drought on ecosystem gas exchange at three Mediterranean sites. The three sites include two nearly monospecific Quercus ilex L. forests, one on karstic limestone (Puéchabon), the other on fluvial sand with access to groundwater (Castelporziano), and a typical multispecies shrubland on limestone (Arca di Noè). A canopy gas exchange model Process Pixel Net Ecosystem Exchange (PROXELNEE), which contains the Farquhar photosynthesis model coupled to stomatal conductance via the Ball-Berry model, was inverted in order to estimate the seasonal time course of canopy parameters from hourly values of ecosystem gross carbon uptake and transpiration. It was shown that an inverse estimation of leaf-level parameters was impossible when optimizing against ecosystem H2O or CO2 fluxes alone (unidentifiable parameters). In contrast, a criterion that constrained the optimization against both H2O and CO2 fluxes yielded stable estimates of leaf-level parameters. Two separate model inversions were implemented to test two alternative hypotheses about the response to drought: a reduction in active leaf area as a result of patchy stomatal closure or a change in photosynthetic capacities. In contrast to a previously tested hypothesis of classical (uniform) stomatal control, both hypotheses were equally able to describe the seasonality of carbon uptake and transpiration on all three sites, with a decline during the drought and recovery after autumn rainfall. Large reductions of up to 80%, in either active leaf area or photosynthetic capacities, were necessary to describe the observed carbon and water fluxes at the end of the drought period. With a threshold-type relationship, soil water content was an excellent predictor of these changes. With the drought-dependent parameter changes included, the canopy model explains 80-90% of the variance of hourly gross CO2 uptake (root mean squared error (RMSE): 1.1-2.6 μmol m-2 s-1) and 70-80% of the variance of hourly transpiration (RMSE: 0.02-0.03 mm h-1) at all sites. In addition to drought effects, changes in leaf photosynthetic activity not related to water availability, i.e., high spring activity, were detected through the inverse modeling approach. Moreover, our study exemplifies a kind of multiconstraint inverse modeling that can be profitably used for calibrating ecosystem models that are meant for global applications with ecosystem flux data.

  11. The assemblage WO2 + H2O as a steady-state hydrogen source in moderately reduced hydrothermal experiments

    USGS Publications Warehouse

    Cygan, G.L.; I-Ming, Chou

    1990-01-01

    The values of fH2 for the assemblage WO2 + WO2.72 + H2O (designated as WO) have been measured in sealed Au capsules under an external pressure of 2 kbar CH4 and between 650 and 800??C using Ag-AgBr-HBr sensors of fH2. The fH2 values obtained can be represented by the equation log(fWOH2)2kbar,T(??0.06) = (-1924.9 ??(T,K) + 4.06 and are found to be slightly greater than those associated with the previously calibrated C-CH4 buffer. -from Authors

  12. Materials Data on CuP2(H2O3)2 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-10

    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

  13. Atmospheric isoprene ozonolysis: impacts of stabilized Criegee intermediate reactions with SO2, H2O and dimethyl sulfide

    NASA Astrophysics Data System (ADS)

    Newland, M. J.; Rickard, A. R.; Vereecken, L.; Muñoz, A.; Ródenas, M.; Bloss, W. J.

    2015-03-01

    Isoprene is the dominant global biogenic volatile organic compound (VOC) emission. Reactions of isoprene with ozone are known to form stabilised Criegee intermediates (SCIs), which have recently been shown to be potentially important oxidants for SO2 and NO2 in the atmosphere; however the significance of this chemistry for SO2 processing (affecting sulfate aerosol) and NO2 processing (affecting NOx levels) depends critically upon the fate of the SCI with respect to reaction with water and decomposition. Here, we have investigated the removal of SO2 in the presence of isoprene and ozone, as a function of humidity, under atmospheric boundary layer conditions. The SO2 removal displays a clear dependence on relative humidity, confirming a significant reaction for isoprene derived SCI with H2O. Under excess SO2 conditions, the total isoprene ozonolysis SCI yield was calculated to be 0.56 (±0.03). The observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + H2O)/k(SCI + SO2), of 5.4 (±0.8) × 10-5 for isoprene derived SCI. The relative rate constant for k(SCI decomposition)/k(SCI + SO2) is 8.4 (±5.0) × 1010 cm-3. Uncertainties are ±2σ and represent combined systematic and precision components. These kinetic parameters are based on the simplification that a single SCI species is formed in isoprene ozonolysis, an approximation which describes the results well across the full range of experimental conditions. Our data indicate that isoprene-derived SCIs are unlikely to make a substantial contribution to gas-phase SO2 oxidation in the troposphere. We also present results from an analogous set of experiments, which show a clear dependence of SO2 removal in the isoprene-ozone system as a function of dimethyl sulfide concentration. We propose that this behaviour arises from a rapid reaction between isoprene-derived SCI and DMS; the observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + DMS)/k(SCI + SO2), of 4.1 (±2.2). This result suggests that SCIs may contribute to the oxidation of DMS in the atmosphere and that this process could therefore influence new particle formation in regions impacted by emissions of unsaturated hydrocarbons and DMS.

  14. Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO2, H2O and dimethyl sulfide

    NASA Astrophysics Data System (ADS)

    Newland, M. J.; Rickard, A. R.; Vereecken, L.; Muñoz, A.; Ródenas, M.; Bloss, W. J.

    2015-08-01

    Isoprene is the dominant global biogenic volatile organic compound (VOC) emission. Reactions of isoprene with ozone are known to form stabilised Criegee intermediates (SCIs), which have recently been shown to be potentially important oxidants for SO2 and NO2 in the atmosphere; however the significance of this chemistry for SO2 processing (affecting sulfate aerosol) and NO2 processing (affecting NOx levels) depends critically upon the fate of the SCIs with respect to reaction with water and decomposition. Here, we have investigated the removal of SO2 in the presence of isoprene and ozone, as a function of humidity, under atmospheric boundary layer conditions. The SO2 removal displays a clear dependence on relative humidity, confirming a significant reaction for isoprene-derived SCIs with H2O. Under excess SO2 conditions, the total isoprene ozonolysis SCI yield was calculated to be 0.56 (±0.03). The observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + H2O) / k(SCI + SO2), of 3.1 (±0.5) × 10-5 for isoprene-derived SCIs. The relative rate constant for k(SCI decomposition) / k(SCI+SO2) is 3.0 (±3.2) × 1011 cm-3. Uncertainties are ±2σ and represent combined systematic and precision components. These kinetic parameters are based on the simplification that a single SCI species is formed in isoprene ozonolysis, an approximation which describes the results well across the full range of experimental conditions. Our data indicate that isoprene-derived SCIs are unlikely to make a substantial contribution to gas-phase SO2 oxidation in the troposphere. We also present results from an analogous set of experiments, which show a clear dependence of SO2 removal in the isoprene-ozone system as a function of dimethyl sulfide concentration. We propose that this behaviour arises from a rapid reaction between isoprene-derived SCIs and dimethyl sulfide (DMS); the observed SO2 removal kinetics are consistent with a relative rate constant, k(SCI + DMS) / k(SCI + SO2), of 3.5 (±1.8). This result suggests that SCIs may contribute to the oxidation of DMS in the atmosphere and that this process could therefore influence new particle formation in regions impacted by emissions of unsaturated hydrocarbons and DMS.

  15. Calcite precipitation from CO 2-H 2O-Ca(OH) 2 slurry under high pressure of CO 2

    NASA Astrophysics Data System (ADS)

    Montes-Hernandez, G.; Renard, F.; Geoffroy, N.; Charlet, L.; Pironon, J.

    2007-10-01

    The formation of solid calcium carbonate (CaCO 3) from aqueous solutions or slurries containing calcium and carbon dioxide (CO 2) is a complex process of considerable importance in the ecological, geochemical and biological areas. Moreover, the demand for powdered CaCO 3 has recently increased considerably in various fields of industry. The aim of this study was therefore to synthesize fine particles of calcite with controlled morphology by hydrothermal carbonation of calcium hydroxide at high CO 2 pressure (initial P=55 bar) and at moderate and high temperatures (30 and 90 °C). The morphology of precipitated particles was identified by transmission electron microscopy (TEM/EDS) and scanning electron microscopy (SEM/EDS). In addition, an X-ray diffraction analysis was performed to investigate the carbonation efficiency and purity of the solid product. Carbonation of dispersed calcium hydroxide (Ca(OH) 2(s)+CO 2(aq)→CaCO 3(s)+H 2O) in the presence of supercritical ( PT=90 bar, T=90 °C) or gaseous ( PT=55 bar, T=30 °C) CO 2 led to the precipitation of sub-micrometric isolated particles (<1 μm) and micrometric agglomerates (<5 μm) of calcite. For this study, the carbonation efficiency (Ca(OH) 2-CaCO 3 conversion) was not significantly affected by pressure-temperature (PT) conditions after 24 h of reaction. In contrast, the initial rate of calcium carbonate precipitation increased from 4.3 mol/h in the "90 bar-90 °C" system to 15.9 mol/h in the "55 bar-30 °C" system. The use of high CO 2 pressure may therefore be desirable for increasing the production rate of CaCO 3, carbonation efficiency and purity, to approximately 48 kg/m 3 h, 95% and 96.3%, respectively, in this study. The dissipated heat for this exothermic reaction was estimated by calorimetry to be -32 kJ/mol in the "90 bar-90 °C" system and -42 kJ/mol in the "55 bar-30 °C" system.

  16. Materials Data on NaCoBP2H2O9 (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

  17. Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature.

    PubMed

    Cai, Xuanxuan; Sun, Wei; Xu, Chaochao; Cao, Limei; Yang, Ji

    2016-09-01

    Selective catalytic reduction of NO X by hydrogen (H2-SCR) in the presence of oxygen has been investigated over the NiCo2O4 and Pd-doped NiCo2O4 catalysts under varying conditions. The catalysts were prepared by a sol-gel method in the presence of oxygen within 50-350 °C and were characterized using XRD, BET, EDS, XPS, Raman, H2-TPR, and NH3-TPD analysis. The results demonstrated that the doped Pd could improve the catalyst reducibility and change the surface acidity and redox properties, resulting in a higher catalytic performance. The performance of NiCo1.95Pd0.05O4 was consistently better than that of NiCo2O4 within the 150-350 °C range at a gas hourly space velocity (GHSV) of 4800 mL g(-1) h(-1), with a feed stream containing 1070 ppm NO, 10,700 ppm H2, 2 % O2, and N2 as balance gas. The effects of GHSV, NO/H2 ratios, and O2 feed concentration on the NO conversion over the NiCo2O4 and NiCo1.95Pd0.05O4 catalysts were also investigated. The two samples similarly showed that an increase in GHSV from 4800 to 9600 mL h(-1) g(-1), the NO/H2 ratio from 1:10 to 1:1, and the O2 content from 0 to 6 % would result in a decrease in NO conversion. In addition, 2 %, 5 %, and 8 % H2O into the feed gas had a slightly negative influence on SCR activity over the two catalysts. The effect of SO2 on the SCR activity indicated that the NiCo1.95Pd0.05O4 possesses better SO2 tolerance than NiCo2O4 catalyst does. Graphical abstract The NiCo1.95Pd0.05O4 catalyst achieved over 90 % NO conversion with N2 selectivity of 100 % in the 200∼250 °C range than the maximum 40.5 % NO conversion over NiCo2O4 with N2 selectivity of approximately 80 % in 350 °C.

  18. Deactivation processes of the lowest excited state of [UO2(H2O)5]2+ in aqueous solution.

    PubMed

    Formosinho, Sebastião J; Burrows, Hugh D; da Graça Miguel, Maria; Azenha, M Emília D G; Saraiva, Isabel M; Ribeiro, A Catarina D N; Khudyakov, Igor V; Gasanov, Rashid G; Bolte, Michèle; Sarakha, Mohamed

    2003-05-01

    A detailed analysis of the photophysical behaviour of uranyl ion in aqueous solutions at room temperature is given using literature data, together with results of new experimental and theoretical studies to see whether the decay mechanism of the lowest excited state involves physical deactivation by energy transfer or a chemical process through hydrogen atom abstraction. Comparison of the radiative lifetimes determined from quantum yield and lifetime data with that obtained from the Einstein relationship strongly suggests that the emitting state is identical to that observed in the lowest energy absorption band. From study of the experimental rate and that calculated theoretically, from deuterium isotope effects and the activation energy for decay support is given to a deactivation mechanism of hydrogen abstraction involving water clusters to give uranium(v) and hydroxyl radicals. Support for hydroxyl radical formation comes from electron spin resonance spectra observed in the presence of the spin traps 5,5-dimethyl-1-pyrroline N-oxide and tert-butyl-N-phenylnitrone and from literature results on photoinduced uranyl oxygen exchange and photoconductivity. It has previously been suggested that the uranyl emission above pH 1.5 may involve an exciplex between excited uranyl ion and uranium(v). Evidence against this mechanism is given on the basis of quenching of uranyl luminescence by uranium(v), together with other kinetic reasoning. No overall photochemical reaction is observed on excitation of aqueous uranyl solutions, and it is suggested that this is mainly due to reoxidation of UO2+ by hydroxyl radicals in a radical pair. An alternative process involving oxidation by molecular oxygen is analysed experimentally and theoretically, and is suggested to be too slow to be a major reoxidation pathway.

  19. CO2 and humidity removal system for extended Shuttle missions - CO2, H2O, and trace contaminant equilibrium testing

    NASA Technical Reports Server (NTRS)

    Davis, S. H.; Kissinger, L. D.

    1977-01-01

    The equilibrium relationships for the co-adsorption of CO2 and H2O on an amine coated acrylic ester are presented. The equilibrium data collection and reduction techniques are discussed. Based on the equilibrium relationship, other modes of operation of systems containing HS-C are discussed and specific space applications for HS-C are presented. Equilibrium data for 10 compounds which are found as trace contaminants in closed environments are also presented.

  20. CFD Convective Flow Simulation of the Varying Properties of CO2-H2O Mixtures in Geothermal Systems

    PubMed Central

    Yousefi, S.; Atrens, A. D.; Sauret, E.; Dahari, M.; Hooman, K.

    2015-01-01

    Numerical simulation of a geothermal reservoir, modelled as a bottom-heated square box, filled with water-CO2 mixture is presented in this work. Furthermore, results for two limiting cases of a reservoir filled with either pure water or CO2 are presented. Effects of different parameters including CO2 concentration as well as reservoir pressure and temperature on the overall performance of the system are investigated. It has been noted that, with a fixed reservoir pressure and temperature, any increase in CO2 concentration leads to better performance, that is, stronger convection and higher heat transfer rates. With a fixed CO2 concentration, however, the reservoir pressure and temperature can significantly affect the overall heat transfer and flow rate from the reservoir. Details of such variations are documented and discussed in the present paper. PMID:25879074

  1. Magnetic properties of the S=1/2 square lattice antiferromagnet CuF2(H2O)2(pyz)

    SciTech Connect

    Wang, Cuihuan; Lumsden, Mark D; Fishman, Randy Scott; Ehlers, Georg; Hong, Tao; Tian, Wei; Cao, Huibo; Podlesnyak, Andrey A; Dunmars, C; Schlueter, J. A.; Manson, J. L.; Christianson, Andrew D

    2012-01-01

    We have performed elastic and inelastic neutron scattering experiments on single crystal samples of the coordination polymer compound CuF{sub 2}(H{sub 2}O){sub 2}(pyz) (pyz = pyrazine) to study the magnetic structure and excitations. The elastic neutron diffraction measurements indicate a collinear antiferromagnetic structure with moments oriented along the [0.7 0 1] real-space direction and an ordered moment of 0.60 {+-} 0.03 {micro}B/Cu. This value is significantly smaller than the single-ion magnetic moment, reflecting the presence of strong quantum fluctuations. The spin wave dispersion from magnetic zone center to the zone boundary points (0.5 1.5 0) and (0.5 0 1.5) can be described by a two-dimensional Heisenberg model with a nearest-neighbor magnetic exchange constant J{sub 2D} = 0.934 {+-} 0.0025 meV. The interlayer interaction J{sub perp} in this compound is less than 1.5% of J{sub 2D}. The spin excitation energy at the (0.5 0.5 0.5) zone boundary point is reduced when compared to the (0.5 1 0.5) zone boundary point by {approx}10.3% {+-} 1.4%. This zone boundary dispersion is consistent with quantum Monte Carlo and series expansion calculations for the S=1/2 Heisenberg square lattice antiferromagnet, which include corrections for quantum fluctuations to linear spin wave theory.

  2. Determining noble gas partitioning within a CO2-H2O system at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Warr, Oliver; Rochelle, Christopher A.; Masters, Andrew; Ballentine, Christopher J.

    2015-06-01

    Quantifying the distribution of noble gases between phases is essential for using these inert trace gases to track the processes controlling multi-phase subsurface systems. Here we present experimental data that defines noble gas partitioning for two phase CO2-water systems. These are at the pressure and temperature range relevant for engineered systems used for anthropogenic carbon capture and geological storage (CCS) technologies, and CO2-rich natural gas reservoirs (CO2 density range 169-656 kg/m3 at 323-377 K and 89-134 bar). The new partitioning data are compared to predictions of noble gas partitioning determined in low-pressure, pure noble gas-water systems for all noble gases except neon and radon. At low CO2 density there was no difference between measured noble gas partitioning and that predicted in pure noble gas-water systems. At high CO2 density, however, partition coefficients express significant deviation from pure noble gas-water systems. At 656 kg/m3, these deviations are -35%, 74%, 113% and 319% for helium, argon, krypton and xenon, respectively. A second order polynomial fit to the data for each noble gas describes the deviation from the pure noble gas-water system as a function of CO2 density. We argue that the difference between pure noble gas-water systems and the high density CO2-water system is due to an enhanced degree of molecular interactions occurring within the dense CO2 phase due to the combined effect of inductive and dispersive forces acting on the noble gases. As the magnitude of these forces are related to the size and polarisability of each noble gas, xenon followed by krypton and argon become significantly more soluble within dense CO2. In the case of helium repulsive forces dominate and so it becomes less soluble as a function of CO2 density.

  3. Measurement of regional cerebral blood flow in cat brain using intracarotid 2H2O and 2H NMR imaging

    SciTech Connect

    Detre, J.A.; Subramanian, V.H.; Mitchell, M.D.; Smith, D.S.; Kobayashi, A.; Zaman, A.; Leigh, J.S. Jr. )

    1990-05-01

    Cerebral blood flow (CBF) was measured in cat brain in vivo at 2.7 T using 2H NMR to monitor the washout of deuterated saline injected into both carotid arteries via the lingual arteries. In anesthetized cats, global CBF varied directly with PaCO{sub 2} over a range of 20-50 mm Hg, and the corresponding global CBF values ranged from 25 to 125 ml.100 g-1.min-1. Regional CBF was measured in a 1-cm axial section of cat brain using intracarotid deuterated saline and gradient-echo 2H NMR imaging. Blood flow images with a maximum pixel resolution of 0.3 x 0.3 x 1.0 cm were generated from the deuterium signal washout at each pixel. Image derived values for CBF agreed well with other determinations, and decreased significantly with hypocapnia.

  4. A laser flash photolysis kinetics study of the reaction OH + H2O2 yields HO2 + H2O

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Semmes, D. H.; Ravishankara, A. R.

    1981-01-01

    Absolute rate constants for the reaction are reported as a function of temperature over the range 273-410 K. OH radicals are produced by 266 nm laser photolysis of H2O2 and detected by resonance fluorescence. H2O2 concentrations are determined in situ in the slow flow system by UV photometry. The results confirm the findings of two recent discharge flow-resonance fluorescence studies that the title reaction is considerably faster, particularly at temperatures below 300 K, than all earlier studies had indicated. A table giving kinetic data from the reaction is included.

  5. Concentrations of CH4, CO, CO2, H2, H2O and N2O in the upper stratosphere

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Heidt, L. E.; Lueb, R. H.; Martell, E. A.

    1975-01-01

    On 23 May 1973 a cryogenic air sampler was flown on an Aerobee rocket from White Sands Missile Range. A large air sample was collected between 40 and 50 km altitude and successfully recovered for water vapor and trace gas analysis. The results were as follows: water vapor, 4.0 (+1.3 or - 0.9) ppmV; methane, 0.37 + or - 0.01 ppmV; molecular hydrogen, 0.47 + or - 0.02 ppmV; carbon monoxide, 0.05 + or - 0.01 ppmV; carbon dioxide, 316.2 + or - 2.8 ppmV; and nitrous oxide, 3 + or - 7 ppb.

  6. Synergetic inactivation of Staphylococcus epidermidis and Streptococcus mutansin a TiO2/H2O2/UV system.

    PubMed

    Unosson, Erik; Tsekoura, Eleni K; Engqvist, Håkan; Welch, Ken

    2013-01-01

    TiO 2 photocatalysis can be used to kill surface adherent bacteria on biomaterials, and is particularly interesting for use with percutaneous implants and devices. Its efficiency and safety, however, depend on the activation energy required. This in vitro study investigates synergetic effects against the clinically relevant strains S. epidermidis and S. mutans when combining photocatalytic surfaces with H2O2. After 20 min exposure to 0.1 wt% H2O2 and UV light on TiO2 surfaces, viabilities of S. epidermidis and S. mutans were reduced by 99.7% and 98.9%, respectively. Without H2O2 the corresponding viability reduction was 86% for S. epidermidis and 65% for S. mutans. This study indicates that low concentrations of H2O2 can enhance the efficiency of photocatalytic TiO2 surfaces, which could potentially improve current techniques used for decontamination and debridement of TiO2 coated biomedical implants and devices.

  7. Pressure-driven orbital reorientations and coordination-sphere reconstructions in [CuF2(H2O)2(pyz)

    SciTech Connect

    Prescimone, A.; Morien, C.; Allan, D.; Schlueter, J.; Tozer, S.; Manson, J. L.; Parsons, S.; Brechin, E. K.; Hill, S.

    2012-07-23

    Successive reorientations of the Jahn-Teller axes associated with the Cu{sup II} ions accompany a series of pronounced structural transitions in the title compound, as is shown by X-ray crystallography and high-frequency EPR measurements. The second transition forces a dimerization involving two thirds of the Cu{sup II} sites due to ejection of one of the water molecules from the coordination sphere

  8. Chemoselective Reductive Amination of Carbonyl Compounds for the Synthesis of Tertiary Amines Using SnCl2·2H2O/PMHS/MeOH.

    PubMed

    Nayal, Onkar S; Bhatt, Vinod; Sharma, Sushila; Kumar, Neeraj

    2015-06-05

    Stannous chloride catalyzed chemoselective reductive amination of a variety of carbonyl compounds with aromatic amines has been developed for the synthesis of a diverse range of tertiary amines using inexpensive polymethylhydrosiloxane as reducing agent in methanol. The present method is also applicable for the synthesis of secondary amines including heterocyclic ones.

  9. Be3(AsO4)2 2H2O, a New Berylloarsenate Phase Containing Bridged Tetrahedral 3-Rings

    DTIC Science & Technology

    1994-04-15

    CsH(ZnPO 4 )2 and NaH(ZnPO 4 )2 contain "bridged" 3-rings as part of anionic layers sandwiching cesium and sodium cations (9). Finally, the novel...0 have been found in the layered, anionic zincophosphate phases CsH(ZnPO 4 )2 and NaH(ZnP0 4 )2 (9). However, the precise nature of the tetrahedral

  10. Structural determination; vibration study and thermal decomposition of [C5H6N5]2SeO4ṡ2H2O

    NASA Astrophysics Data System (ADS)

    Ben Hassen, C.; Boujelbene, M.; Mhiri, T.

    2015-01-01

    The present paper reports the chemical synthesis, structure study, thermal analysis, and vibrational properties of new hybrid compound called: bis (adeninium) selenate bihydrates. It is crystallized in the triclinic system with P-1 space group and the following parameters a = 7.804(5) Å; b = 9.686 (5) Å; c = 11.771 (5) Å; α = 84.421(5)°; ß = 77.556(5)°; γ = 81.186 (5)°; Z = 2 and V = 856.7(8) Å3. The structure is built up from tunnels containing all the components of the structure and following to the c axis, linked via three types of hydrogen bonds (Nsbnd H…O, Nsbnd H…N and Osbnd H…O). The thermal decomposition of precursors studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), indicate the existence of two mass loss region correspond to dehydration and degradation of the title compound, respectively. The existence of vibrational modes correspond to the organic and inorganic groups and water molecular are identified by the IR and Raman spectroscopy in the frequency ranges 400-4000 and 300-1600 cm-1, respectively.

  11. Absolute rate constant of the reaction OH + H2O2 yields HO2 + H2O from 245 to 423 K

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.

    1980-01-01

    The absolute rate constant of the reaction between the hydroxyl radical and hydrogen peroxide was measured by using the discharge-flow resonance fluorescence technique at total pressure between 1 and 4 torr. At 298 K the result is (1.64 + or - 0.32) x 10 to the -12th cu cm/molecule s. The observed rate constant is independent of pressure, surface-to-volume ratio, the addition of vibrational quenchers, and the source of OH. The temperature dependence has also been determined between 245 and 423 K; the resulting Arrhenius expression is k cu cm/molecule s is equal to (2.51 + or - 0.6) x 10 to the -12th exp(-126 + or - 76/T).

  12. Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System

    SciTech Connect

    Pili, E.; Kennedy, B.M.; Conrad, M.E.; Gratier, J.-P.

    2010-12-15

    To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite {delta}{sup 13}C and fluid inclusion {sup 3}He/{sup 4}He is consistent with a mantle origin for a fraction of the infiltrating CO{sub 2}. Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H{sub 2}O and CO{sub 2} in faulting, supporting the involvement of deep fluids percolating through and perhaps weakening the fault zone. There is no clear evidence for a significant contribution from meteoric water, except for overprinting related to late weathering.

  13. Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains

    SciTech Connect

    Fischer, Marc L.; Billesbach, David P.; Berry, Joseph A.; Riley,William J.; Torn, Margaret S.

    2007-06-13

    Climate, vegetation cover, and management create fine-scaleheterogeneity in unirrigated agricultural regions, with important but notwell-quantified consequences for spatial and temporal variations insurface CO2, water, and heat fluxes. We measured eddy covariance fluxesin seven agricultural fields--comprising winter wheat, pasture, andsorghum--in the U.S. Southern Great Plains (SGP) during the 2001-2003growing seasons. Land-cover was the dominant source of variation insurface fluxes, with 50-100 percent differences between fields planted inwinter-spring versus fields planted in summer. Interannual variation wasdriven mainly by precipitation, which varied more than two-fold betweenyears. Peak aboveground biomass and growing-season net ecosystem exchange(NEE) of CO2 increased in rough proportion to precipitation. Based on apartitioning of gross fluxes with a regression model, ecosystemrespiration increased linearly with gross primary production, but with anoffset that increased near the time of seed production. Because theregression model was designed for well-watered periods, it successfullyretrieved NEE and ecosystem parameters during the peak growing season,and identified periods of moisture limitation during the summer. Insummary, the effects of crop type, land management, and water limitationon carbon, water, and energy fluxes were large. Capturing the controllingfactors in landscape scale models will be necessary to estimate theecological feedbacks to climate and other environmental impactsassociated with changing human needs for agricultural production of food,fiber, and energy.

  14. Effect of SO2 on oxidation of metallic materials in CO2/H2O-rich gases relevant to oxyfuel environments

    SciTech Connect

    Huczkowski, P; Olszewski, T; Schiek, M; Lutz, B; Holcomb, G R; Shemet, V; Nowak, W; Meier, G H; Singheiser, L; Quadakkers, W J

    2014-01-01

    In an oxyfuel plant, heat exchanging metallic components will be exposed to a flue gas that contains substantially higher contents of CO2, water vapor, and SO2 than conventionalflue gases. In the present study, the oxidation behavior of the martensitic steel P92 was studied in CO2-and/or H2O-rich gas mixtures with and without addition of SO2. For this purpose, the corrosion of P92 at 550 8C up to 1000 h in Ar–H2O–SO2, Ar–CO2–SO2, Ar–CO2–O2–SO2 and simulated oxyfuel gas (Ar–CO2–H2O–O2–SO2) was compared with the behavior in selected SO2-free gases. The oxidation kinetics were estimated by a number of methods such as optical microscopy, scanning electron microscopy with energy and wave length dispersive X-ray analysis, glow discharge optical emission spectroscopy, X-ray diffraction as well as transmission electron microscopy. The experimental results revealed that the effect of SO2 addition on the materials behavior substantially differed, depending on the prevailing base gas atmosphere. The various types of corrosion attack affected by SO2 could not be explained by solely comparing equilibrium activities of the gas atmospheres with thermodynamic stabilities of possible corrosion products. The results were found to be strongly affected by relative rates of reactions of the various gas species occurring within the frequently porous corrosion scales as well as at the scale/gas-and scale/alloy interfaces.Whereas SO2 addition to Ar–CO2 resulted in formation of an external mixed oxide/sulflde layer, the presence of SO2 in oxyfuel gas and in Ar–H2O–SO2 resulted in Fe-sulflde formation near the interface between inner and outer oxide layer as well as Cr-sulflde formation in the alloy. In the latter gases, the presence of SO2 seemed to have no dramatic effect on oxide scale growth rates.

  15. Dissolution of aragonite-strontianite solid solutions in nonstoichiometric Sr (HCO3)2-Ca (HCO3)2-CO2-H2O solutions

    USGS Publications Warehouse

    Plummer, L.N.; Busenberg, E.; Glynn, P.D.; Blum, A.E.

    1992-01-01

    Synthetic strontianite-aragonite solid-solution minerals were dissolved in CO2-saturated non-stoichiometric solutions of Sr(HCO3)2 and Ca(HCO3)2 at 25??C. The results show that none of the dissolution reactions reach thermodynamic equilibrium. Congruent dissolution in Ca(HCO3)2 solutions either attains or closely approaches stoichiometric saturation with respect to the dissolving solid. In Sr(HCO3)2 solutions the reactions usually become incongruent, precipitating a Sr-rich phase before reaching stoichiometric saturation. Dissolution of mechanical mixtures of solids approaches stoichiometric saturation with respect to the least stable solid in the mixture. Surface uptake from subsaturated bulk solutions was observed in the initial minutes of dissolution. This surficial phase is 0-10 atomic layers thick in Sr(HCO3)2 solutions and 0-4 layers thick in Ca(HCO3)2 solutions, and subsequently dissolves and/or recrystallizes, usually within 6 min of reaction. The initial transient surface precipitation (recrystallization) process is followed by congruent dissolution of the original solid which proceeds to stoichiometric saturation, or until the precipitation of a more stable Sr-rich solid. The compositions of secondary precipitates do not correspond to thermodynamic equilibrium or stoichiometric saturation states. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of solid solutions on surfaces of aragonite and strontianite single crystals immersed in Sr(HCO3)2 and Ca(HCO3)2 solutions, respectively. In Sr(HCO3)2 solutions, the XPS signal from the outer ~ 60 A?? on aragonite indicates a composition of 16 mol% SrCO3 after only 2 min of contact, and 14-18 mol% SrCO3 after 3 weeks of contact. The strontianite surface averages approximately 22 mol% CaCO3 after 2 min of contact with Ca(HCO3)2 solution, and is 34-39 mol% CaCO3 after 3 weeks of contact. XPS analysis suggests the surface composition is zoned with somewhat greater enrichment in the outer ~25 A?? (as much as 26 mol% SrCO3 on aragonite and 44 mol% CaCO3 on strontianite). The results indicate rapid formation of a solid-solution surface phase from subsaturated aqueous solutions. The surface phase continually adjusts in composition in response to changes in composition of the bulk fluid as net dissolution proceeds. Dissolution rates of the endmembers are greatly reduced in nonstoichiometric solutions relative to dissolution rates observed in stoichiometric solutions. All solids dissolve more slowly in solutions spiked with the least soluble component ((Sr(HCO3)2)) than in solutions spiked with the more soluble component (Ca(HCO3)2), an effect that becomes increasingly significant as stoichiometric saturation is approached. It is proposed that the formation of a non-stoichiometric surface reactive zone significantly decreases dissolution rates. ?? 1992.

  16. Reduction of Nitro Aromatic Compounds in Fe(0) -CO2-H2O Systems: Implications for Groundwater Remediation with Iron Metal

    DTIC Science & Technology

    1995-07-01

    Washington, DC 20503 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE July 1995 3. REPORT TYPE AND DATES COVERED Thesis for Masters 1995 4. TITLE AND...Agrawal Ph.D. in Geology University of North Carolina at Chapel Hill, 1990 A thesis submitted to the faculty of the Oregon Graduate Institute of...Abinash Agrawal has been examined and approved by the following Examination Committee: Paul G. Tratnyek, Thesis Advisor Assistant Professor Carl D

  17. Testing the H2O2-H2O hypothesis for life on Mars with the TEGA instrument on the Phoenix lander.

    PubMed

    Schulze-Makuch, Dirk; Turse, Carol; Houtkooper, Joop M; McKay, Christopher P

    2008-04-01

    In the time since the Viking life-detection experiments were conducted on Mars, many missions have enhanced our knowledge about the environmental conditions on the Red Planet. However, the martian surface chemistry and the Viking lander results remain puzzling. Nonbiological explanations that favor a strong inorganic oxidant are currently favored (e.g., Mancinelli, 1989; Plumb et al., 1989; Quinn and Zent, 1999; Klein, 1999; Yen et al., 2000), but problems remain regarding the lifetime, source, and abundance of that oxidant to account for the Viking observations (Zent and McKay, 1994). Alternatively, a hypothesis that favors the biological origin of a strong oxidizer has recently been advanced (Houtkooper and Schulze-Makuch, 2007). Here, we report on laboratory experiments that simulate the experiments to be conducted by the Thermal and Evolved Gas Analyzer (TEGA) instrument of the Phoenix lander, which is to descend on Mars in May 2008. Our experiments provide a baseline for an unbiased test for chemical versus biological responses, which can be applied at the time the Phoenix lander transmits its first results from the martian surface.

  18. Correlation of the depletion layer with the Helmholtz layer in the anatase TiO2-H2O interface via molecular dynamics simulations.

    PubMed

    Sang, Lixia; Zhang, Yudong; Wang, Jun; Zhao, Yangbo; Chen, Yi-Tung

    2016-06-01

    Molecular dynamics simulations have been conducted to study the interaction between anatase TiO2(001), (100), and (101) surfaces and water at room temperature. The dynamic interfacial structure and properties of water on anatase TiO2 surfaces are obtained by analyzing the water density, the diffusion coefficient of water, the surface charge distribution, electric fields and the electrostatic potential distribution. The simulation results have revealed that a highly-ordered water layer structure can be formed near to the anatase TiO2 surface and have also given the Helmholtz layer width and potential drop at the water-TiO2 interface. By correlating the Helmholtz layer with the depletion layer, the depletion layer widths of three surfaces (001), (100), and (101) have been calculated as 474 Å, 237 Å and 99 Å, respectively. The resulting order of the photoelectrochemical activity of the anatase TiO2 surfaces is (001) > (100) > (101), which is consistent with the experimental results. This study may provide a useful correlation of the depletion layer with the Helmholtz layer based on simulations results for the prediction of the behavior and the control of photon-energy conversion devices.

  19. Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

    USGS Publications Warehouse

    Hostetler, P.B.; Christ, C.L.

    1968-01-01

    Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq2+ + 6OHaq- + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90??C, yields the value of Kchr = 10-49.2 ?? 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0??C to 200??C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0??C, rises to a maximum value of 10-48.5 at approximately 135??C, and is 10-49.1 at 200??C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90??C value is 10-49.1, in excellent agreement with the experimental value; for 25??C, the calculated value is 10-50.8. ?? 1968.

  20. Melting relations of hydrous pyrolite in CaO-MgO-Al2O3-SiO2-H2O System at the transition zone pressures

    NASA Astrophysics Data System (ADS)

    Litasov, Konstantin; Ohtani, Eiji; Taniguchi, Hiromitsu

    Phase relations and melt compositions in CaO-MgO-Al2O3-SiO2-pyrolite under hydrous (+2% of H2O) and anhydrous conditions have been determined at 13-20 GPa and 1600-2220°C. Liquidus and solidus temperatures for the hydrous system are about 50-100°C and 180-240°C lower than those for the dry system, respectively. Majorite is a liquidus phase of the hydrous pyrolite from 13 to 20 GPa. Olivine is a liquidus phase at 13 GPa and both periclase and majorite are the liquidus phases at 20 GPa in the dry pyrolite. We observed expansion of the stability field of anhydrous phase B in hydrous experiments. Compositions of partial melts at 13-20 GPa are generally similar in dry and hydrous systems, but hydrous melts contain more SiO2 at 13-17 GPa. The melts formed by low degree of melting have Al2O3-depleted and CaO-rich compositions. Trends of hydrous melt compositions are generally consistent with those of aluminum-depleted komatiite magmas.

  1. Reduction of pertechnetate by acetohydroxamic acid: Formation of [TcNO(AHA)2(H2O)]+ and implications for the UREX process.

    SciTech Connect

    1Harry Reid Center for Environmental Studies, Nuclear Science and Technology Division, University of Nevada, Las Vegas, Las Vegas, NV, 89154-4006; Gong, Cynthia-May S; Poineau, Frederic; Lukens, Wayne W; Czerwinski, Kenneth R.

    2008-02-26

    Reductive nitrosylation and complexation of ammonium pertechnetate by acetohydroxamic acid has been achieved in aqueous nitric and perchloric acid solutions. The kinetics of the reaction depend on the relative concentrations of the reaction components and are accelerated at higher temperatures. The reaction does not occur unless conditions are acidic. Analysis of the x-ray absorption fine structure spectroscopic data is consistent with a pseudo-octahedral geometry with the linear Tc-N-O bond typical of technetium nitrosyl compounds, and electron spin resonance spectroscopy is consistent with a the d{sup 5} Tc(II) nitrosyl complex. The nitrosyl source is generally AHA, but may be augmented by products of reaction with nitric acid. The resulting low-valency trans-aquonitrosyl(diacetohydroxamic)-technetium(II) complex (1) is highly soluble in water, extremely hydrophilic, and is not extracted by tri-n-butylphosphate in a dodecane diluent. Its extraction properties are not pH-dependent; titration studies indicate a single species from pH 4.5 down to -0.6 (calculated). This molecule is resistant to oxidation by H{sub 2}O{sub 2}, even at high pH, and can undergo substitution to form other technetium nitrosyl complexes. The formation of 1 may strongly impact the fate of technetium in the nuclear fuel cycle.

  2. Be(3)(AsO4)2.2H2O, a New Berylloarsenate Phase Containing ’Bridged’ Tetrahedral 3-Rings

    DTIC Science & Technology

    1993-02-15

    in a gold tube and heated to 5500ýC for 135 hours in a Leco TEMPRESTM bomb. Upon cooling, numerous needle- and shard -like crystals were recovered...in handlizg these materials. The structure of Be3 (AsOi) 2 .2H 2 0 was determined by standard single- crystal X-ray meth- ods (11). A suitable shard of...habit colorless shard crystal system monoclinic a (A) 16.318(2) b (A) 4.6664(3) C (A) 9.8755(7) C (0) 93.777(3) V (A3) 750.37 Z 4 space group C2/c

  3. Effect of glycine addition on the structural, thermal, optical, mechanical and electrical properties of Sr (HCOO)2·2H2O crystals

    NASA Astrophysics Data System (ADS)

    Muthupoongodi, S.; Theodore David Manickam, S.; Mahadevan, C. K.; Angel Mary Greena, J.; Balakumar, S.; Sahaya Shajan, X.

    2015-10-01

    Pure and glycine doped strontium formate dihydrate (SFD) single crystals were grown by the free evaporation method to understand the effect of glycine addition on the structural, thermal, optical, mechanical and electrical properties of SFD crystal. The grown crystals were characterized by carrying out powder X-ray diffraction, high resolution X-ray diffraction, Fourier transform infrared spectral, Raman spectral, UV-vis-NIR spectral, thermogravimetric (TG/DTA), second harmonic generation (SHG), microhardness and DC electrical conductivity measurements. Results obtained in the present study indicate improvement in crystalline perfection, optical transmittance, and SHG efficiency, and change in microhardness, and DC electrical conductivity on doping SFD with glycine. In addition, a large size (~1.9 cm length, ~1.2 cm breath and ~0.6 cm height) SFD crystal with good optical quality could be grown successfully by the seeded free evaporation method.

  4. Ecosystem CO2/H2O fluxes are explained by hydraulically limited gas exchange during tree mortality from spruce bark beetles

    NASA Astrophysics Data System (ADS)

    Frank, John M.; Massman, William J.; Ewers, Brent E.; Huckaby, Laurie S.; Negrón, José F.

    2014-06-01

    Disturbances are increasing globally due to anthropogenic changes in land use and climate. This study determines whether a disturbance that affects the physiology of individual trees can be used to predict the response of the ecosystem by weighing two competing hypothesis at annual time scales: (a) changes in ecosystem fluxes are proportional to observable patterns of mortality or (b) to explain ecosystem fluxes the physiology of dying trees must also be incorporated. We evaluate these hypotheses by analyzing 6 years of eddy covariance flux data collected throughout the progression of a spruce beetle (Dendroctonus rufipennis) epidemic in a Wyoming Engelmann spruce (Picea engelmannii)-subalpine fir (Abies lasiocarpa) forest and testing for changes in canopy conductance (gc), evapotranspiration (ET), and net ecosystem exchange (NEE) of CO2. We predict from these hypotheses that (a) gc, ET, and NEE all diminish (decrease in absolute magnitude) as trees die or (b) that (1) gc and ET decline as trees are attacked (hydraulic failure from beetle-associated blue-stain fungi) and (2) NEE diminishes both as trees are attacked (restricted gas exchange) and when they die. Ecosystem fluxes declined as the outbreak progressed and the epidemic was best described as two phases: (I) hydraulic failure caused restricted gc, ET (28 ± 4% decline, Bayesian posterior mean ± standard deviation), and gas exchange (NEE diminished 13 ± 6%) and (II) trees died (NEE diminished 51 ± 3% with minimal further change in ET to 36 ± 4%). These results support hypothesis b and suggest that model predictions of ecosystem fluxes following massive disturbances must be modified to account for changes in tree physiological controls and not simply observed mortality.

  5. Simulation of Canopy CO2/H2O Fluxes for a Rubber (Hevea Brasiliensis) Plantation in Central Cambodia: The Effect of the Regular Spacing of Planted Trees

    SciTech Connect

    Kumagai, Tomo'omi; Mudd, Ryan; Miyazawa, Yoshiyuki; Liu, Wen; Giambelluca, Thomas; Kobayashi, N.; Lim, Tiva Khan; Jomura, Mayuko; Matsumoto, Kazuho; Huang, Maoyi; Chen, Qi; Ziegler, Alan; Yin, Song

    2013-09-10

    We developed a soil-vegetation-atmosphere transfer (SVAT) model applicable to simulating CO2 and H2O fluxes from the canopies of rubber plantations, which are characterized by distinct canopy clumping produced by regular spacing of plantation trees. Rubber (Hevea brasiliensis Müll. Arg.) plantations, which are rapidly expanding into both climatically optimal and sub-optimal environments throughout mainland Southeast Asia, potentially change the partitioning of water, energy, and carbon at multiple scales, compared with traditional land covers it is replacing. Describing the biosphere-atmosphere exchange in rubber plantations via SVAT modeling is therefore essential to understanding the impacts on environmental processes. The regular spacing of plantation trees creates a peculiar canopy structure that is not well represented in most SVAT models, which generally assumes a non-uniform spacing of vegetation. Herein we develop a SVAT model applicable to rubber plantation and an evaluation method for its canopy structure, and examine how the peculiar canopy structure of rubber plantations affects canopy CO2 and H2O exchanges. Model results are compared with measurements collected at a field site in central Cambodia. Our findings suggest that it is crucial to account for intensive canopy clumping in order to reproduce observed rubber plantation fluxes. These results suggest a potentially optimal spacing of rubber trees to produce high productivity and water use efficiency.

  6. Ro-vibrational spectrum of H2O-Ne in the ν2 H2O bending region: A combined ab initio and experimental investigation

    NASA Astrophysics Data System (ADS)

    Liu, Xunchen; Hou, Dan; Thomas, Javix; Li, Hui; Xu, Yunjie

    2016-12-01

    High resolution ro-vibrational transitions of the H2O-Ne complex in the ν2 bending region of H2O at 6 μm have been measured using a rapid scan infrared spectrometer based on an external cavity quantum cascade laser and an astigmatic multipass optical cell. To aid the spectral assignment, a four-dimension potential energy surface of H2O-Ne which depends on the intramolecular bending coordinate of the H2O monomer and the three intermolecular vibrational coordinates has been constructed and the rovibrational transitions have been calculated. Three ortho and two para H2O-20Ne bands have been identified from the experimental spectra. Some weaker transitions belonging to H2O-22Ne have also been identified experimentally. Spectroscopic fits have been performed for both the experimental and theoretical transition frequencies using a simple pseudo-diatomic Hamiltonian including both Coriolis coupling and Fermi resonance terms. The experimental and theoretical spectroscopic constants thus obtained have been compared. Further improvements needed in the potential energy surface and the related spectral simulation have been discussed.

  7. Reduction of Pertechnetate By Acetohydroxamic Acid: Formation of [tc**II(NO)(AHA)(2)(H(2)O)]**+ And Implications for the UREX Process

    SciTech Connect

    Gong, C.-M.S.; Lukens, W.W.; Poineau, F.; Czerwinski, K.R.

    2009-05-18

    Reductive nitrosylation and complexation of ammonium pertechnetate by acetohydroxamic acid has been achieved in aqueous nitric and perchloric acid solutions. The kinetics of the reaction depend on the relative concentrations of the reaction components and are accelerated at higher temperatures. The reaction does not occur unless conditions are acidic. Analysis of the X-ray absorption fine structure spectroscopic data is consistent with a pseudo-octahedral geometry and the linear Tc-N-O bond typical of technetium nitrosyl compounds, and electron spin resonance spectroscopy is consistent with a d{sup 5} Tc(II) nitrosyl complex. The nitrosyl source is generally AHA, but it may be augmented by some products of the reaction with nitric acid. The resulting low-valency trans-aquonitrosyl(diacetohydroxamic)-technetium(II) complex ([Tc{sup II}(NO)(AHA){sub 2}H{sub 2}O]{sup +}, 1) is highly soluble in water, extremely hydrophilic, and is not extracted by tri-n-butylphosphate in a dodecane diluent. Its extraction properties are not pH-dependent: potentiometric-spectrophotometric titration studies indicate a single species from pH 4 down to -0.6 (calculated). This molecule is resistant to oxidation by H{sub 2}O{sub 2}, even at high pH, and can undergo substitution to form other technetium nitrosyl complexes. The potential formation of 1 during reprocessing may strongly impact the fate of technetium in the nuclear fuel cycle.

  8. Crystal and molecular structure of the dihydrate of the artificial sweetener lactitol: 4-O-β- D-galactopyranosyl- D-glucitol.2H 2O

    NASA Astrophysics Data System (ADS)

    Kanter, Jan A.; Schouten, Arie; van Bommel, Mark

    1990-10-01

    Crystallization of lactitol from aqueous ethanol readily yields crystals of the monohydrate, the structure of which has recently been reported. Slow evaporation of very concentrated aqueous syrups results in the crystalline dihydrate. The space group is P4 32 12 with a = 8.762(2), c = 45.508(8) Å, V = 3493.8(13) Å 3, Z = 8, Dc = 1.446 g cm -3, R = 0.037 for 2017 unique observed reflections and 310 variables. The galactopyranosyl ring has the 4C1 chair conformation and the carbon chain of the glucitol fragment has a non-planar, bent MAA conformation. The conformations about the glycosidic C(1)O(1) and O(1)C(14) bonds are different from those observed in the monohydrate: the torsion angles O(5)C(1)O(1)C(14) and C(1)O(1)C(14)C(13) differ by 29.6° and 15.0°, respectively. The orientations of the terminal C(11)O(11) bonds with respect to the carbon-atom chain of the glucitol fragment also differ appreciably: in the dihydrate the pertinent torsion angle is -47.3(3)° and in the monohydrate 75.5(2)°. All hydroxyl groups are involved in a complex three-dimensional system of hydrogen bonds, in which the two water molecules constitute an important cohesive element

  9. The H2O2+OH → HO2+H2O reaction in aqueous solution from a charge-dependent continuum model of solvation

    SciTech Connect

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

    2008-07-07

    We applied our recently developed protocol of the conductor-like continuum model of solvation to describe the title reaction in aqueous solution. The model has the unique feature of the molecular cavity being dependent on the atomic charges in the solute, and can be extended naturally to transition states and reaction pathways. It was used to calculate the reaction energetics and reaction rate in solution for the title reaction. The rate of reaction calculated using canonical variational transition state theory CVT in the context of the equilibrium solvation path (ESP) approximation, and including correction for tunneling through the small curvature approximation (SCT) was found to be 3.6 106 M-1 s-1, in very good agreement with experiment, These results suggest that the present protocol of the conductor-like continuum model of solvation with the charge-dependent cavity definition captures accurately the solvation effects at transition states and allows for quantitative estimates of reaction rates in solutions. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  10. Rapid syntheses of a metal-organic framework material Cu3(BTC)2(H2O)3 under microwave: a quantitative analysis of accelerated syntheses.

    PubMed

    Khan, Nazmul Abedin; Haque, Enamul; Jhung, Sung Hwa

    2010-03-20

    A typical MOF material, Cu-BTC has been synthesized with microwave and conventional electric heating in various conditions to elucidate, for the first time, the quantitative acceleration in the synthesis of a MOF by microwaves. The acceleration by microwaves is mainly due to rapid nucleation rather than rapid crystal growth, even though both stages are accelerated. The acceleration in the nucleation stage by microwaves is due to the very large pre-exponential factor (about 1.4 x 10(10) times that of conventional synthesis) in the Arrhenius plot. However, the activation energy for the nucleation in the case of microwave synthesis is higher than the activation energy of conventional synthesis. The large acceleration in the nucleation, compared with that in the crystal growth, is observed once again by the syntheses in two-steps (changing heating methods from microwave into conventional heating or from conventional heating into microwave heating just after the nucleation is completed). The crystal size of Cu-BTC obtained by microwave-nucleation is generally smaller than the Cu-BTC made by conventional-nucleation, probably due to rapid nucleation and the small size of nuclei with microwave-nucleation.

  11. Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

    SciTech Connect

    Bryan, Charles R.; Dewers, Thomas A.; Heath, Jason E.; Wang, Yifeng; Matteo, Edward N.; Meserole, Stephen P.; Tallant, David Robert

    2013-09-01

    In the supercritical CO2-water-mineral systems relevant to subsurface CO2 sequestration, interfacial processes at the supercritical fluid-mineral interface will strongly affect core- and reservoir-scale hydrologic properties. Experimental and theoretical studies have shown that water films will form on mineral surfaces in supercritical CO2, but will be thinner than those that form in vadose zone environments at any given matric potential. The theoretical model presented here allows assessment of water saturation as a function of matric potential, a critical step for evaluating relative permeabilities the CO2 sequestration environment. The experimental water adsorption studies, using Quartz Crystal Microbalance and Fourier Transform Infrared Spectroscopy methods, confirm the major conclusions of the adsorption/condensation model. Additional data provided by the FTIR study is that CO2 intercalation into clays, if it occurs, does not involve carbonate or bicarbonate formation, or significant restriction of CO2 mobility. We have shown that the water film that forms in supercritical CO2 is reactive with common rock-forming minerals, including albite, orthoclase, labradorite, and muscovite. The experimental data indicate that reactivity is a function of water film thickness; at an activity of water of 0.9, the greatest extent of reaction in scCO2 occurred in areas (step edges, surface pits) where capillary condensation thickened the water films. This suggests that dissolution/precipitation reactions may occur preferentially in small pores and pore throats, where it may have a disproportionately large effect on rock hydrologic properties. Finally, a theoretical model is presented here that describes the formation and movement of CO2 ganglia in porous media, allowing assessment of the effect of pore size and structural heterogeneity on capillary trapping efficiency. The model results also suggest possible engineering approaches for optimizing trapping capacity and for monitoring ganglion formation in the subsurface.

  12. The thermal stability of sideronatrite and its decomposition products in the system Na2O-Fe2O3-SO2-H2O

    NASA Astrophysics Data System (ADS)

    Ventruti, Gennaro; Scordari, Fernando; Della Ventura, Giancarlo; Bellatreccia, Fabio; Gualtieri, Alessandro F.; Lausi, Andrea

    2013-09-01

    The thermal stability of sideronatrite, ideally Na2Fe3+(SO4)2(OH)·3(H2O), and its decomposition products were investigated by combining thermogravimetric and differential thermal analysis, in situ high-temperature X-ray powder diffraction (HT-XRPD) and Fourier transform infrared spectroscopy (HT-FTIR). The data show that for increasing temperature there are four main dehydration/transformation steps in sideronatrite: (a) between 30 and 40 °C sideronatrite transforms into metasideronatrite after the loss of two water molecules; both XRD and FTIR suggest that this transformation occurs via minor adjustments in the building block. (b) between 120 and 300 °C metasideronatrite transforms into metasideronatrite II, a still poorly characterized phase with possible orthorhombic symmetry, consequently to the loss of an additional water molecule; X-ray diffraction data suggest that metasideronatrite disappears from the assemblage above 175 °C. (c) between 315 and 415 °C metasideronatrite II transforms into the anhydrous Na3Fe(SO4)3 compound. This step occurs via the loss of hydroxyl groups that involves the breakdown of the [Fe3+(SO4)2(OH)]{∞/2-} chains and the formation of an intermediate transient amorphous phase precursor of Na3Fe(SO4)3. (d) for T > 500 °C, the Na3Fe(SO4)3 compound is replaced by the Na-sulfate thenardite, Na2SO4, plus Fe-oxides, according to the Na3Fe3+(SO4)3 → 3/2 Na2(SO4) + 1/2 Fe2O3 + SOx reaction products. The Na-Fe sulfate disappears around 540 °C. For higher temperatures, the Na-sulfates decomposes and only hematite survives in the final product. The understanding of the thermal behavior of minerals such as sideronatrite and related sulfates is important both from an environmental point of view, due to the presence of these phases in evaporitic deposits, soils and sediments including extraterrestrial occurrences, and from the technological point of view, due to the use of these materials in many industrial applications.

  13. Aqueous Sulfate Separation by Sequestration of [(SO4)2(H2O)4]4 Clusters within Highly Insoluble Imine-Linked Bis-Guanidinium Crystals

    DOE PAGES

    Custelcean, Radu; Williams, Neil J.; Seipp, Charles A.; ...

    2015-12-18

    Quantitative removal of sulfate from seawater was achieved by selective crystallization of the anion with a bis(guanidinium) ligand self-assembled in situ through imine condensation of simple components. The resulting crystalline salt has an exceptionally low aqueous solubility, on a par with BaSO4. Single-crystal X-ray diffraction analysis revealed pairs of sulfate anions clustered together with four water molecules within the crystals.

  14. 2-μm Coherent DIAL for CO2, H2O and Wind Field Profiling in the Lower Atmosphere: Instrumentation and Results

    NASA Astrophysics Data System (ADS)

    Gibert, Fabien; Edouart, Dimitri; Cénac, Claire; Pellegrino, Jessica; Le Mounier, Florian; Dumas, Arnaud

    2016-06-01

    We report on 2-μm coherent differential absorption lidar (CDIAL) measurements of carbon dioxide (CO2), water vapour (H2O) absorption and wind field profiling in the atmospheric boundary layer. The CDIAL uses a Tm:fiber pumped, single longitudinal mode Q-switched seeded Ho:YLF laser and a fibercoupled coherent detection. The laser operates at a pulse repetition frequency of 2 kHz and emits an output energy of 10 mJ with a pulse width of 40 ns (FWHM). Experimental horizontal and vertical range-resolved measurements were made in the atmospheric boundary layer and compared to colocated in-situ sensor data.

  15. Major, Trace, and Volatile (CO2, H2O, S, F, and Cl) Elements from 1000+ Hawaiian Olivine-hosted Melt Inclusions Reveal the Dynamics of Crustal Recycling

    NASA Astrophysics Data System (ADS)

    Marske, J. P.; Hauri, E. H.; Trusdell, F.; Garcia, M. O.; Pietruszka, A. J.

    2015-12-01

    Global cycling of volatile elements (H2O, CO2, F, S, Cl) via subduction to deep mantle followed by entrainment and melting within ascending mantle plumes is an enigmatic process that controls key aspects of hot spot volcanism (i.e. melting rate, magma supply, degassing, eruptive style). Variations in radiogenic isotope ratios (e.g.187Os/188Os) at hot spots such as Hawaii reveal magmatic processes within deep-seated mantle plumes (e.g. mantle heterogeneity, lithology, and melt transport). Shield-stage lavas from Hawaii likely originate from a mixed plume source containing peridotite and recycled oceanic crust (pyroxenite) based on variations of radiogenic isotopes. Hawaiian lavas display correlations among isotopes, major and trace elements [1] that might be expected to have an expression in the volatile elements. To investigate this link, we present Os isotopic ratios (n=51), and major, trace, and volatile elements from 1003 olivine-hosted melt inclusions (MI) and their host minerals from tephra from Koolau, Mauna Loa, Hualalai, Kilauea, and Loihi volcanoes. The data show a strong correlation between MI volatile contents and incompatible trace element ratios (La/Yb) with Os isotopes of the same host olivines and reveal large-scale volatile heterogeneity and zonation exists within the Hawaiian plume. 'Loa' chain lavas, which are thought to originate from greater proportions of recycled oceanic crust/pyroxenite, have MIs with lower H2O, S, F, and Cl contents compared to 'Kea' chain lavas that were derived from more peridotite-rich sources. The depletion of volatile elements in the 'Loa' volcano MIs can be explained if they tapped an ancient dehydrated oceanic crust component within the Hawaiian plume. Higher extents of melting beneath 'Loa' volcanoes can also explain these depletions. The presence of dehydrated recycled mafic material in the plume source suggests that subduction effectively devolatilizes part of the oceanic crust. These results are similar to the observed shifts in H2O/Ce ratios near the Easter and Samoan hotspots [2,3]. Thus, it appears that multiple hotspots may record relative H2O depletions and possibly other volatiles. [1] Hauri et al. 1996, Nature 382, 415-419. [2] Dixon et al. 2002, Nature 420:385-89 [3] Workman et al. 2006, EPSL 241:932-51.

  16. Evidence for micro-biological induction of {101} montmartre twinning of gypsum (CaSO 4 ⋯ 2H 2O)

    NASA Astrophysics Data System (ADS)

    Cody, A. M.; Cody, R. D.

    1989-12-01

    Natural gypsum crystals twinned on d{101} have been found almost exclusively in deposits from saline lakes and secondary mine alterations. The presence of α-amylase, an enzyme excreted into soils and water by bacteria, fungi, algae, and plant roots, was found to induce d{101} twinning of gypsum crystals formed by diffusion in laboratory growth experiments. From this evidence, extensive deposits of d{101} twinned crystals such as those of the Paris Basin are proposed to form in the α-amylase concentrations that results from certain microbial blooms.

  17. Shock initiation and detonation study on high concentration H2O2/H2O solutions using in-situ magnetic gauges

    SciTech Connect

    Sheffield, Stephen A; Dattelbaum, Dana M; Stahl, David B; Gibson, L Lee; Bartram, Brian D; Engelke, Ray

    2010-01-01

    Concentrated hydrogen peroxide (H{sub 2}O{sub 2}) has been known to detonate for many years. However, because of its reactivity and the difficulty in handling and confining it, along with the large critical diameter, few studies providing basic information about the initiation and detonation properties have been published. We are conducting a study to understand and quantify the initiation and detonation properties of highly concentrated H{sub 2}O{sub 2} using a gas-driven two-stage gun to produce well defined shock inputs. Multiple magnetic gauges are used to make in-situ measurements of the growth of reaction and subsequent detonation in the liquid. These experiments are designed to be one-dimensional to eliminate any difficulties that might be encountered with large critical diameters. Because of the concern of the reactivity of the H{sub 2}O{sub 2} with the confining materials, a remote loading system has been developed. The gun is pressurized, then the cell is filled and the experiment shot within less than three minutes. Several experiments have been completed on {approx}98 wt % H{sub 2}O{sub 2}/H{sub 2}O mixtures; homogeneous shock initiation behavior has been observed in the experiments where reaction is observed. The initial shock pressurizes and heats the mixture. After an induction time, a thermal explosion type reaction produces an evolving reactive wave that strengthens and eventually overdrives the first wave producing a detonation. From these experiments, we have determined unreacted Hugoniot points, times-to-detonation points that indicate low sensitivity (an input of 13.5 GPa produces detonation in 1 {micro}s compared to 9.5 GPa for neat nitromethane), and detonation velocities of high concentration H{sub 2}O{sub 2}/H{sub 2}O solutions of over 6.6 km/s.

  18. Anomalous dispersion of sulfur in quinidine sulfate, (C20H25N2O2)2SO4·2H2O: Implications for structure analysis

    PubMed Central

    Karle, Isabella L.; Karle, Jerome

    1981-01-01

    A Patterson-type map computed with Bijvoet differences squared as coefficients, (ǀFhǀ - ǀF-hǀ)2, as recommended by Rossmann, readily yielded the position of the S atom. The experiment was performed with Cu Kα radiation which is far from the absorption edge for sulfur. The coordinates of the remainder of the 54C, N, and O atoms were derived by means of partial structure development by use of the tangent formula. The latter was used only to effect phase extension, not phase refinement. A main purpose of this experiment was to reaffirm, as first shown in the investigation of the protein crambin by Hendrickson and Teeter, that, in the presence of a large number of lighter atoms, sulfur atoms can be located by use of anomalous dispersion at wave-lengths far from the absorption edge. The space group is P21 with a = 26.718(8) Å, b = 6.987(3) Å, c = 10.857(6) Å, and β = 99.51(4)° and contains two quinidyl ions, one sulfate ion, and two water molecules per asymmetric unit. The conformations of the two independent quinidyl ions differ mainly in the torsional angle of the bond between the vinyl side chain and the quinuclidine moiety. The R factor is 4.9% for all 2869 data. PMID:16593097

  19. The reactivity of sodium alanates with O[2], H[2]O, and CO[2] : an investigation of complex metal hydride contamination in the context of automotive systems.

    SciTech Connect

    Dedrick, Daniel E.; Bradshaw, Robert W.; Behrens, Richard, Jr.

    2007-08-01

    Safe and efficient hydrogen storage is a significant challenge inhibiting the use of hydrogen as a primary energy carrier. Although energy storage performance properties are critical to the success of solid-state hydrogen storage systems, operator and user safety is of highest importance when designing and implementing consumer products. As researchers are now integrating high energy density solid materials into hydrogen storage systems, quantification of the hazards associated with the operation and handling of these materials becomes imperative. The experimental effort presented in this paper focuses on identifying the hazards associated with producing, storing, and handling sodium alanates, and thus allowing for the development and implementation of hazard mitigation procedures. The chemical changes of sodium alanates associated with exposure to oxygen and water vapor have been characterized by thermal decomposition analysis using simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and X-ray diffraction methods. Partial oxidation of sodium alanates, an alkali metal complex hydride, results in destabilization of the remaining hydrogen-containing material. At temperatures below 70 C, reaction of sodium alanate with water generates potentially combustible mixtures of H{sub 2} and O{sub 2}. In addition to identifying the reaction hazards associated with the oxidation of alkali-metal containing complex hydrides, potential treatment methods are identified that chemically stabilize the oxidized material and reduce the hazard associated with handling the contaminated metal hydrides.

  20. Testing the H2O2-H2O Hypothesis for Life on Mars with the TEGA Instrument on the Phoenix Lander

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, D.; Turse, Carol; Houtkooper, Joop M.; McKay, Christopher P.

    2008-04-01

    In the time since the Viking life-detection experiments were conducted on Mars, many missions have enhanced our knowledge about the environmental conditions on the Red Planet. However, the martian surface chemistry and the Viking lander results remain puzzling. Nonbiological explanations that favor a strong inorganic oxidant are currently favored (e.g., Mancinelli, 1989; Plumb et al., 1989; Quinn and Zent, 1999; Klein, 1999; Yen et al., 2000), but problems remain regarding the lifetime, source, and abundance of that oxidant to account for the Viking observations (Zent and McKay, 1994). Alternatively, a hypothesis that favors the biological origin of a strong oxidizer has recently been advanced (Houtkooper and Schulze-Makuch, 2007). Here, we report on laboratory experiments that simulate the experiments to be conducted by the Thermal and Evolved Gas Analyzer (TEGA) instrument of the Phoenix lander, which is to descend on Mars in May 2008. Our experiments provide a baseline for an unbiased test for chemical versus biological responses, which can be applied at the time the Phoenix lander transmits its first results from the martian surface.

  1. Photocrystallography at TriCS/SINQ: light-induced structural changes in Na 2[Fe(CN) 5NO]2H 2O

    NASA Astrophysics Data System (ADS)

    Schefer, J.; Schaniel, D.; Woike, Th.; Imlau, M.

    2004-07-01

    Light-induced metastable electronic states as observed e.g. in sodium nitroprusside are of fundamental interest for data storage and optical computing. Structural functionality and therefore the light-induced structure itself is of basic interest in such systems. As neutrons are sensitive to the position of the nucleus and non-destructive with respect to the metastable electronic states, neutron photocrystallography provides a useful method to determine light-induced structural changes. A photocrystallographic experimental setup has been built-up at SINQ and has been successfully used at the single-crystal instrument TriCS and the test facility TOPSI (now called MORPHEUS).

  2. Results from Boiling Temperature Measurements for Saturated Solutions in the Systems NaCl + Ca(NO3)2 + H2O, NaNO3 + KNO3 + H2O, and NaCl + KNO3 + H2O, and Dry Out Temperatures for NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O

    SciTech Connect

    Rard, J A

    2005-11-29

    Boiling temperature measurements have been made for saturated ternary solutions of NaCl + KNO{sub 3} + H{sub 2}O and NaNO{sub 3} + KNO{sub 3} + H{sub 2}O at three selected salt ratios and for NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O over the full composition range. The maximum boiling temperature found for the NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O system is 164.7 {+-} 0.6 C, and the composition is estimated to occur at x(Ca(NO{sub 3}){sub 2}) {approx} 0.25. Experiments were also performed for the five component NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O mixtures with the molar ratio of NaCl:NaNO{sub 3}:KNO{sub 3} held essentially constant at 1:0.9780:1.1468 as the solute mole fraction of Ca(NO{sub 3}){sub 2}, x(Ca(NO{sub 3}){sub 2}), was varied between 0 and 0.25. The NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O system forms low melting mixtures and thus boiling temperatures for saturated were not determined. Instead, the temperatures corresponding to the cessation of boiling (i.e., dry out temperatures) of these liquid mixtures were determined. These dry out temperatures range from {approx} 300 C when x(Ca(NO{sub 3}){sub 2}) = 0 to {ge} 400 C when x(Ca(NO{sub 3}){sub 2}) = 0.20 and 0.25. The investigated mixture compositions correspond to some of the major mineral assemblages that are predicted to control the deliquescence relative humidity of salts formed by leaching dust samples from the proposed nuclear repository at Yucca Mountain, Nevada.

  3. Mechanistic Studies of Methanol Synthesis over Cu from CO/CO2/H2/H2O Mixtures: the Source of C in Methanol and the Role of Water

    SciTech Connect

    Yang, Yong; Mims, Charles A.; Mei, Donghai; Peden, Charles HF; Campbell, Charles T.

    2013-02-01

    The low temperature (403 – 453K) conversions of CO:hydrogen and CO2:hydrogen mixtures (6 bar total pressure) to methanol over copper catalysts are both assisted by the presence of small amounts of water (mole fraction ~0.04%-0.5%). For CO2:hydrogen reaction mixtures, the water product from both methanol synthesis and reverse water gas shift serves to initiate both reactions in an autocatalytic manner. In the case of CO:D2 mixtures, very little methanol is produced until small amounts of water are added. The effect of water on methanol production is more immediate than in CO2:D2, yet the steady state rates are similar. Tracer experiments in 13CO:12CO2:hydrogen (with or without added water), show that the dominant source of C in the methanol product gradually shifts from CO2 to CO as the temperature is lowered. Cu-bound formate, the major IR visible surface species under CO2:hydrogen, is not visible in CO:moist hydrogen. Though formate is visible in the tracer experiments, the symmetric stretch is absent. These results, in conjunction with recent DFT calculations on Cu(111), point to carboxyl as a common intermediate for both methanol synthesis and reverse water gas shift, with formate playing a spectator co-adsorbate role.

  4. Structure determination of neptunium(VI) mu3-hydroxobenzoate, [(NpO2)2(mu3-OH)2(H5C6COO)2] x 2 H2O.

    PubMed

    Charushnikova, Iraida A; Krot, Nikolai N; Makarenkov, Vadim I

    2010-09-06

    Neptunium(VI) benzoate with mu(3)-OH(-) has been isolated and studied by the X-ray method. The main structural motive in the crystal is corrugated ribbons [(NpO(2))(2)(mu(3)-OH)(2)(C(7)H(5)O(2))(2)](n) extended along the c axes in which three neptunium pentagonal bipyramids are linked through the mu(3)-OH(-) ligand. The benzoate ions are arranged at both sides of the ribbons, and each anion binds two adjacent NpO(2). The water molecules are arranged in the channels along the c axis.

  5. CO2-H2O Mixtures in the Geological Sequestration of CO2. II. Partitioning in Chloride Brines at 12-100oC and up to 600 bar

    SciTech Connect

    Spycher, Nicolas; Pruess, Karsten

    2004-09-13

    Correlations presented by Spycher et al. (2003) to compute the mutual solubilities of CO2 and H2O are extended to include the effect of chloride salts in the aqueous phase. This is accomplished by including, in the original formulation, activity coefficients for aqueous CO2 derived from several literature sources, primarily for NaCl solutions. Best results are obtained when combining the solubility correlations of Spycher et al. (2003) with the activity coefficient formulation of Rumpf et al. (1994) and Duan and Sun (2003), which can be extended to chloride solutions other than NaCl. This approach allows computing mutual solubilities in a noniterative manner with an accuracy typically within experimental uncertainty for solutions up to 6 molal NaCl and 4 molal CaCl2.

  6. Boiling Temperature and Reversed Deliquescence Relative Humidity Measurements for Mineral Assemblages in the NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O System

    SciTech Connect

    Rard, J A; Staggs, K J; Day, S D; Carroll, S A

    2005-12-01

    Boiling temperature measurements have been made at ambient pressure for saturated ternary solutions of NaCl + KNO{sub 3} + H{sub 2}O, NaNO{sub 3} + KNO{sub 3} + H{sub 2}O, and NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O over the full composition range, along with those of the single salt systems. Boiling temperatures were also measured for the four component NaCl + NaNO{sub 3} + KNO{sub 3} + H{sub 2}O and five component NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O mixtures, where the solute mole fraction of Ca(NO{sub 3}){sub 2}, x(Ca(NO{sub 3}){sub 2}), was varied between 0 and 0.25. The maximum boiling temperature found for the NaCl + KNO{sub 3} + H{sub 2}O system is {approx} 134.9 C; for the NaNO{sub 3} + KNO{sub 3} + H{sub 2}O system is {approx} 165.1 C at x(NaNO{sub 3}) {approx} 0.46 and x(KNO{sub 3}) {approx} 0.54; and for the NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O system is 164.7 {+-} 0.6 C at x(NaCl) {approx} 0.25 and x(Ca(NO{sub 3}){sub 2}) {approx} 0.75. The NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O system forms molten salts below their maximum boiling temperatures, and the temperatures corresponding to the cessation of boiling (dry out temperatures) of these liquid mixtures were determined. These dry out temperatures range from {approx} 300 C when x(Ca(NO{sub 3}){sub 2}) = 0 to {ge} 400 C when x(Ca(NO{sub 3}){sub 2}) = 0.20 and 0.25. Mutual deliquescence/efflorescence relative humidity (MDRH/MERH) measurements were also made for the NaNO{sub 3} + KNO{sub 3} and NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture from 120 to 180 C at ambient pressure. The NaNO{sub 3} and NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture has a MDRH of 26.4% at 120 C and 20.0% at 150 C. This salt mixture also absorbs water at 180 C, which is higher than expected from the boiling temperature experiments. The NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture was found to have a MDRH of 25.9% at 120 C and 10.5% at 180 C. The investigated mixture compositions correspond to some of the major mineral assemblages that are predicted to control brine composition due to the deliquescence of salts formed in dust deposited on waste canisters in the proposed nuclear repository at Yucca Mountain, Nevada.

  7. 2H2O incorporation into hepatic acetyl-CoA and de novo lipogenesis as measured by Krebs cycle-mediated 2H-enrichment of glutamate and glutamine.

    PubMed

    Silva, Ana Maria; Martins, Fatima; Jones, John G; Carvalho, Rui

    2011-12-01

    Deuterated water is widely used for measuring de novo lipogenesis on the basis of quantifying lipid (2)H-enrichment relative to that of body water. However, incorporation of (2)H-enrichment from body water into newly synthesized lipid molecules is incomplete therefore the true lipid precursor enrichment differs from that of body water. We describe a novel measurement of de novo lipogenesis that is based on a true precursor-product analysis of hepatic acetyl-CoA and triglyceride methyl enrichments from deuterated water. After deuterated water administration to seven in situ and seven perfused livers, acetyl-CoA methyl enrichment was inferred from (2)H nuclear magnetic resonance analysis of hepatic glutamate/glutamine (Glx) enrichment and triglyceride methyl enrichment was directly determined by (2)H nuclear magnetic resonance of triglycerides. Acetyl-CoA (2) H-enrichment was 71% ± 1% that of body water for in situ livers and 53% ± 2% of perfusate water for perfused livers. From the ratio of triglyceride-methyl/acetyl-CoA enrichments, fractional de novo lipogenesis rates of 0.97% ± 0.09%/2 hr and 7.92% ± 1.47%/48 hr were obtained for perfused and in situ liver triglycerides, respectively. Our method reveals that acetyl-CoA enrichment is significantly less than body water both for in situ and perfused livers. Furthermore, the difference between acetyl-CoA and body water enrichments is sensitive to the experimental setting.

  8. McCrillisite, NaCs(Be,Li)Zr2(PO4)4.1-2H2O, a new mineral species from Mount Mica, Oxford County, Maine, and new data for gainesite

    USGS Publications Warehouse

    Foord, E.E.; Brownfield, M.E.; Lichte, F.E.; Davis, A.M.; Sutley, S.J.

    1994-01-01

    McCrillisite, a member of the gainesite group, occurs in the Mount Mica granitic pegmatite, South Paris, Oxford County, Maine. The mineral is a product of late-stage hydrothermal alteration and is associated with approximately 20 other silicate, oxide, carbonate, arsenite and phosphate minerals. Crystals occur in mm- to cm-sized cavities, and individuals are up to 1.2 mm in maximum dimension. The crystallography and mineral chemistry of McCrillisite are described. -from Authors

  9. A vibrational spectroscopic study of the phosphate mineral cyrilovite Na(Fe3+)3(PO4)2(OH)4·2(H2O) and in comparison with wardite.

    PubMed

    Frost, Ray L; Xi, Yunfei; Scholz, Ricardo

    2013-05-01

    Vibrational spectroscopy enables subtle details of the molecular structure of cyrilovite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. Cyrilovite is the Fe(3+) member of the wardite group. The infrared and Raman spectroscopy were applied to compare the structure of cyrilovite with that of wardite. The Raman spectrum of cyrilovite in the 800-1400 cm(-1) spectral range shows two intense bands at 992 and 1055 cm(-1) assigned to the ν1PO4(3-) symmetric stretching vibrations. A series of low intensity bands at 1105, 1136, 1177 and 1184 cm(-1) are assigned to the ν3PO4(3-) antisymmetric stretching modes. The infrared spectrum of cyrilovite in the 500-1300 cm(-1) shows much greater complexity than the Raman spectrum. Strong infrared bands are found at 970 and 1007 cm(-1) and are attributed to the ν1PO4(3-) symmetric stretching mode. Raman bands are observed at 612 and 631 cm(-1) and are assigned to the ν4 out of plane bending modes of the PO4(3-) unit. In the 2600-3800 cm(-1) spectral range, intense Raman bands for cyrilovite are found at 3328 and 3452 cm(-1) with a broad shoulder at 3194 cm(-1) and are assigned to OH stretching vibrations. Sharp infrared bands are observed at 3485 and 3538 cm(-1). Raman spectroscopy complimented with infrared spectroscopy has enabled the structure of cyrilovite to be ascertained and compared with that of wardite.

  10. Removal of binary dyes mixtures with opposite and similar charges by adsorption, coagulation/flocculation and catalytic oxidation in the presence of CeO2/H2O2 Fenton-like system.

    PubMed

    Issa Hamoud, Houeida; Finqueneisel, Gisèle; Azambre, Bruno

    2016-08-25

    In this study, the removal of binary mixtures of dyes with similar (Orange II/Acid Green 25) or opposite charges (Orange II/Malachite Green) was investigated either by simple adsorption on ceria or by the heterogeneous Fenton reaction in presence of H2O2. First, the CeO2 nanocatalyst with high specific surface area (269 m(2)/g) and small crystal size (5 nm) was characterized using XRD, Raman spectroscopy and N2 physisorption at 77 K. The adsorption of single dyes was studied either from thermodynamic and kinetic viewpoints. It is shown that the adsorption of dyes on ceria surface is highly pH-dependent and followed a pseudo-second order kinetic model. Adsorption isotherms fit well the Langmuir model with a complete monolayer coverage and higher affinity towards Orange II at pH 3, compared to other dyes. For the (Orange II/Acid Green 25) mixture, both the amounts of dyes adsorbed on ceria surface and discoloration rates measured from Fenton experiments were decreased by comparison with single dyes. This is due to the adsorption competition existing onto the same surface Ce(x+) sites and the reaction competition with hydroxyl radicals, respectively. The behavior of the (Orange II/Malachite Green) mixture is markedly different. Dyes with opposite charges undergo paired adsorption on ceria as well as homogeneous and heterogeneous coagulation/flocculation processes, but can also be removed by heterogeneous Fenton process.

  11. The kinetics of dissolution of dolomite in CO2-H2O systems at 1.5 to 65oC and 0 to 1 atm PCO2.

    USGS Publications Warehouse

    Busenberg, E.; Plummer, L.N.

    1982-01-01

    Weight loss measurements at different T and PCO2 during experimental investigations of the dissolution kinetics of eight samples of dolomite permitted recognition of a two-stage process. During the first stage, which is brief, the surface composition of the dolomite becomes enriched with the MgCO3 component and the CaCO3 component dissolves faster. In the second and more important stage both components of the solid are released stoichiometrically, described quantitatively by three parallel consecutive forward reactions and one significant backward reaction. Dissolution rates are apparently more dependent on crystallographic order than on compositional variations. -M.S.

  12. Surface and catalytic elucidation of Rh/gamma-Al2O3 catalysts during NO reduction by C3H8 in the presence of excess O2, H2O, and SO2.

    PubMed

    Pekridis, G; Kaklidis, N; Komvokis, V; Athanasiou, C; Konsolakis, M; Yentekakis, I V; Marnellos, G E

    2010-03-25

    The present study aims at exploring the surface and catalytic behavior of Rh/gamma-Al(2)O(3) catalysts during the selective reduction of NO by C(3)H(8) in the presence of excess oxygen, H(2)O, and SO(2) with particular emphasis on identifying the elementary steps that describe the reaction mechanism. To this end, detailed activity and stability tests were employed and a precise kinetic analysis was carried out at differential conditions to elucidate the effect of each reactant, including H(2)O and SO(2), on the total reaction rate. At the same time, temperature programmed desorption (TPD) studies in combination with in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy were carried out under various reaction conditions to correlate the catalytic performance of Rh/gamma-Al(2)O(3) catalyst with its corresponding surface chemistry. The results reveal that in the absence of H(2)O and SO(2), the reaction follows a typical "reduction" type mechanism, where the active intermediates (NO(X), carboxylates, isocyanates) are interacting to yield the final products. In this reaction sequence the formation of carboxylate (C(x)H(y)O(z)) species is considered as the rate determining step. Water affects in a different way the NO and C(3)H(8) conversion performance of Rh/gamma-Al(2)O(3) catalyst; its effect is totally reversible in the case of C(3)H(8) oxidation, while the NO reduction was permanently affected mainly due to the oxidation of Rh active sites. In contrast, SO(2) poisons both reactions irreversibly via the formation of strongly adsorbed sulfate compounds, which hinder the adsorption and consequently the activation of reactants.

  13. Modelling phase-assemblage diagrams for magnesian metapelites in the system K2O-FeO-MgO-Al2O3-SiO2-H2O: geodynamic consequences for the Monte Rosa nappe, Western Alps

    NASA Astrophysics Data System (ADS)

    Le Bayon, R.; de Capitani, C.; Frey, M.

    2006-04-01

    Magnesian metamorphic rocks with metapelitic mineral assemblage and composition are of great interest in metamorphic petrology for their ability to constrain P- T conditions in terranes where metamorphism is not easily visible. Phase-assemblage diagrams for natural and model magnesian metapelites in the system KFMASH are presented to document how phase relationships respond to water activity, bulk composition, pressure and temperature. The phase assemblages displayed on these phase diagrams are consistent with natural mineral assemblages occurring in magnesian metapelites. It is shown that the equilibrium assemblages at high pressure conditions are very sensitive to a(H2O). Specifically, the appearance of the characteristic HP assemblage chloritoid-talc-phengite-quartz (with excess H2O) in the magnesian metapelites of the Monte Rosa nappe (Western Alps) is due to the reduction of a(H2O). Furthermore, the mineral assemblages are determined by the whole-rock FeO/(FeO+MgO) ratio and effective Al content X A as well as P and T. The predicted mineral associations for the low- and high- X A model bulk compositions of magnesian metapelites at high pressure are not dependent on the X A variations as they show a similar sequence of mineral assemblages. Above 20 kbar, the prograde sequence of assemblages associated with phengite (with excess SiO2 and H2O) for low- and high- X A bulk compositions of magnesian metapelites is: carpholite-chlorite → chlorite-chloritoid → chloritoid-talc → chloritoid-talc-kyanite → talc-garnet-kyanite → garnet-kyanite ± biotite. At low to medium P- T conditions, a low- X A stabilises the phengite-bearing assemblages associated with chlorite, chlorite + K-feldspar and chlorite + biotite while a high- X A results in the chlorite-phengite bearing assemblages associated with pyrophyllite, andalusite, kyanite and carpholite. A high- X A magnesian metapelite with nearly iron-free content stabilises the talc-kyanite-phengite assemblage at moderate to high P- T conditions. Taking into account the effective bulk composition and a(H2O) involved in the metamorphic history, the phase-assemblage diagrams presented here may be applied to all magnesian metapelites that have compositions within the system KFMASH and therefore may contribute to gaining insights into the metamorphic evolution of terranes. As an example, the magnesian metapelites of the Monte Rosa nappe have been investigated, and an exhumation path with P- T conditions for the western roof of the Monte Rosa nappe has been derived for the first time. The exhumation shows first a near-isothermal decompression from the Alpine eclogite peak conditions around 24 kbar and 505°C down to approximately 8 kbar and 475°C followed by a second decompression with concomitant cooling.

  14. Cordierite-garnet-sillimanite-quartz equilibrium: I. New experimental calibration in the system FeO-Al2O3-SiO2-H2O and certain P-T- X H2O relations

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Biswajit; Holdaway, Michael J.

    1994-05-01

    The equilibrium in which hydrous Fe-cordierite breaks down to almandine, sillimanite, quartz, and water was previously experimentally determined by Richardson (1968) and Holdaway and Lee (1977) using QMF buffer and by Weisbrod (1973) using QIF buffer. All these studies yielded similar results — a negative dP/dT slope for the equilibrium curve. However, based on theoretical arguments, Martignole and Sisi (1981), and based on Fe-Mg partitioning experiments on coexisting cordierite and garnet in equilibrium with sillimanite and quartz, Aranovich and Podlesskii (1983) suggested that this equilibrium curve has a positive dP/dT slope and its position depends on the water content of the equilibrium cordierite. We have redetermined this equilibrium using a much improved tecnique of detecting reaction direction, and cordierite starting material that contained virtually no hercynite. Hercynite was present as a contaminant in the cordierites of previous experimental studies and possibly reacted with quartz during the experimental runs to expand the apparent stability field of Fe-cordierite. We synthesized Fe-cordierite from reagent grade oxides at 710°C and 2 kbar (using QMF buffer) with two intermediate stages of grinding and mixing. The cordierite has a unit cell volume of 1574.60 Å3 (molar volume=23.706 J/bar) and no Fe3+ as indicated by X-ray diffraction and room temperature Mössbauer studies respectively. Reaction direction was concluded by noting≥20% change of the ratios of intensities of two key X-ray diffraction peaks of cordierite and almandine. Our results show that the four-phase equilibrium curve passes through the points 2.1 kbar, 650°C and 2.5 kbar, 750°C. This disagrees with all previous experimental studies. H2O in the Fe-cordierite, equilibrated at 2.2 kbar and 700°C and determined by H-extraction line in the stable isotope laboratory, is 1.13 wt% ( n=0.41 moles). H2O content of pure Mg-cordierite equilibrated under identical conditions and determined by thermogravimentric conditions and determined by thermogravimetric analysis is 1.22 wt% ( n=0.40). Similar determinations on Fe-cordierite and Mg-cordierite equilibrated at 2.0 kbar and 650°C show 1.27 wt% ( n=0.46) and 1.47 wt% ( n=0.48) of H2O respectively. Thus, H2O content appears to be independent of Fe/Mg ratio in cordierite, a conclusion which supports previous experimental determinations. The experimentally determined equilibrium curve represents conditions of PH2O=Ptotal. From this we calculated the anhydrous curve representing equilibrium under conditions of X {H2O/V}=0.0. A family of calculated equilibrium curves of constant n {H2O/ Cord } cut the experimentally determined curve at a very small angle indicating a slight variation in n {H2O/ Cord } in cordierite in equilibrium with almandine, sillimanite, and quartz under the conditions of constant X {H2O/V}. Ancther set of calculated equilibrium curves, each representing constant a {H2O/V} demonstrate that the slopes of the curves vary with X {H2O/V}, and are all positive in the full range of 0.0≤ X {H2O/V}≤1.0.

  15. Solubility products of amorphous ferric arsenate and crystalline scorodite (FeAsO 4 · 2H 2O) and their application to arsenic behavior in buried mine tailings

    NASA Astrophysics Data System (ADS)

    Langmuir, Donald; Mahoney, John; Rowson, John

    2006-06-01

    Published solubility data for amorphous ferric arsenate and scorodite have been reevaluated using the geochemical code PHREEQC with a modified thermodynamic database for the arsenic species. Solubility product calculations have emphasized measurements obtained under conditions of congruent dissolution of ferric arsenate (pH < 3), and have taken into account ion activity coefficients, and ferric hydroxide, ferric sulfate, and ferric arsenate complexes which have association constants of 10 4.04 (FeH 2AsO 42+), 10 9.86 (FeHAsO 4+), and 10 18.9 (FeAsO 4). Derived solubility products of amorphous ferric arsenate and crystalline scorodite (as log Ksp) are -23.0 ± 0.3 and -25.83 ± 0.07, respectively, at 25 °C and 1 bar pressure. In an application of the solubility results, acid raffinate solutions (molar Fe/As = 3.6) from the JEB uranium mill at McClean Lake in northern Saskatchewan were neutralized with lime to pH 2-8. Poorly crystalline scorodite precipitated below pH 3, removing perhaps 98% of the As(V) from solution, with ferric oxyhydroxide (FO) phases precipitated starting between pH 2 and 3. Between pH 2.18 and 7.37, the apparent log Ksp of ferric arsenate decreased from -22.80 to -24.67, while that of FO (as Fe(OH) 3) increased from -39.49 to -33.5. Adsorption of As(V) by FO can also explain the decrease in the small amounts of As(V)(aq) that remain in solution above pH 2-3. The same general As(V) behavior is observed in the pore waters of neutralized tailings buried for 5 yr at depths of up to 32 m in the JEB tailings management facility (TMF), where arsenic in the pore water decreases to 1-2 mg/L with increasing age and depth. In the TMF, average apparent log Ksp values for ferric arsenate and ferric hydroxide are -25.74 ± 0.88 and -37.03 ± 0.58, respectively. In the laboratory tests and in the TMF, the increasing crystallinity of scorodite and the amorphous character of the coexisting FO phase increases the stability field of scorodite relative to that of the FO to near-neutral pH values. The kinetic inability of amorphous FO to crystallize probably results from the presence of high concentrations of sulfate and arsenate.

  16. Inactivation of the plasma membrane ATPase of Schizosaccharomyces pombe by hydrogen peroxide and by the Fenton reagent (Fe2+/H2O2): nonradical vs. radical-induced oxidation.

    PubMed

    Sigler, K; Gille, G; Vacata, V; Stadler, N; Höfer, M

    1998-01-01

    In the absence of added Fe2+, the ATPase activity of isolated Schizosaccharomyces pombe plasma membranes (5-7 mumol P(i) per mg protein per min) is moderately inhibited by H2O2 in a concentration-dependent manner. Sizable inactivation occurs only at 50-80 mmol/L H2O2. The process, probably a direct oxidative action of H2O2 on the enzyme, is not induced by the indigenous membrane-bound iron (19.3 nmol/mg membrane protein), is not affected by the radical scavengers mannitol and Tris, and involves a decrease of both the K(m) of the enzyme for ATP and the V of ATP splitting. On exposing the membranes to the Fenton reagent (50 mumol/L Fe2+ + 20 mmol/L H2O2), which causes a fast production of HO. radicals, the ATPase is 50-60% inactivated and 90% of added Fe2+ is oxidized to Fe3+ within 1 min. The inactivation occurs only when Fe2+ is added before H2O2 and can thus bind to the membranes. The lack of effect of radical scavengers (mannitol, Tris) indicates that HO. radicals produced in the bulk phase play no role in inactivation. Blockage of the inactivation by the iron chelator deferrioxamine implies that the process requires the presence of Fe2+ ions bound to binding sites on the enzyme molecules. Added catalase, which competes with Fe2+ for H2O2, slows down the inactivation but in some cases increases its total extent, probably due to the formation of the superoxide radical that gives rise to delayed HO. production.

  17. The Effect of O2, H2O, and N2 on the Fatigue Crack Growth Behavior of an Alpha + Beta Titanium Alloy at 24 C and 177 C

    NASA Technical Reports Server (NTRS)

    Smith, Stephen W.; Piascik, Robert S.

    2001-01-01

    To study the effects of atmospheric species on the fatigue crack growth behavior of an a+B titanium alloy (Ti 6-2-2-2-2) at room temperature and 177 C, fatigue tests were performed in laboratory air, ultrahigh vacuum, and high purity water vapor, oxygen, nitrogen and helium at various partial pressures. Accelerated fatigue crack growth rates in laboratory air compared to ultrahigh vacuum are linked to the damaging effects of both water vapor and oxygen. Observations of the fatigue crack growth behavior in ultrahigh purity environments, along with surface film analysis using X-ray photoelectron spectroscopy (XPS), suggest that multiple crack-tip processes govern the damaging effects of air. Three possible mechanisms are proposed: 1) at low pressure (less than 10(exp -1) Pa), accelerated da/dN is likely due to monolayer adsorption on crack-tip surfaces presumably resulting in decreased bond strengths at the fatigue crack tip, 2) for pressures greater than 10(exp -1) Pa, accelerated da/dN in oxygen may result from oxidation at the crack tip limiting reversible slip, and 3) in water vapor, absorption of atomic hydrogen at the reactive crack tip resulting in process zone embrittlement.

  18. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, Manabu; Garland, Rebecca M.; Pöschl, Ulrich

    2010-05-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals [1]. The model is based on multiple experimental studies of PAH degradation and on the Pöschl-Rudich-Ammann (PRA) framework [2] for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude, and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude. The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller. The desorption lifetimes and adsorption enthalpies suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, γO3 of PAH-coated aerosol particles are expected to be in the range of 10-6 - 10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17 - 10-16 cm2 s-1 and 10-15 - 10-12 cm2 s-1, respectively. The chemical half-life of PAHs is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems. References: [1] Shiraiwa et al., Atmos. Chem. and Phys., 9, 9571-9586 (2009). [2] Pöschl et al., Atmos. Chem. and Phys., 7, 5989-6023 (2007).

  19. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): Degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Garland, R. M.; Pöschl, U.

    2009-12-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl-Rudich-Ammann, 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3 ≍ 10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3 ≍ 10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O ≍ 10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 and physisorption of H2O. Note, however, that the exact reaction mechanisms, rate limiting steps and possible intermediates still remain to be resolved (e.g., surface diffusion and formation of O atoms or O3- ions at the surface). The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, γO3 of PAH-coated aerosol particles are expected to be in the range of 10-6-10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17-10-16 cm2 s-1 and 10-15-10-12 cm2 s-1, respectively. The chemical half-life of PAHs is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems, and we suggest that it may serve as a basis for the development of a general master mechanism of aerosol and cloud surface chemistry.

  20. Kinetic double-layer model of aerosol surface chemistry and gas-particle interactions (K2-SURF): degradation of polycyclic aromatic hydrocarbons exposed to O3, NO2, H2O, OH and NO3

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Garland, R. M.; Pöschl, U.

    2009-09-01

    We present a kinetic double-layer surface model (K2-SURF) that describes the degradation of polycyclic aromatic hydrocarbons (PAHs) on aerosol particles exposed to ozone, nitrogen dioxide, water vapor, hydroxyl and nitrate radicals. The model is based on multiple experimental studies of PAH degradation and on the PRA framework (Pöschl et al., 2007) for aerosol and cloud surface chemistry and gas-particle interactions. For a wide range of substrates, including solid and liquid organic and inorganic substances (soot, silica, sodium chloride, octanol/decanol, organic acids, etc.), the concentration- and time-dependence of the heterogeneous reaction between PAHs and O3 can be efficiently described with a Langmuir-Hinshelwood-type mechanism. Depending on the substrate material, the Langmuir adsorption constants for O3 vary over three orders of magnitude (Kads,O3≍10-15-10-13 cm3), and the second-order rate coefficients for the surface layer reaction of O3 with different PAH vary over two orders of magnitude (kSLR,PAH,O3≍10-18-10-17 cm2 s-1). The available data indicate that the Langmuir adsorption constants for NO2 are similar to those of O3, while those of H2O are several orders of magnitude smaller (Kads,H2O≍10-18-10-17 cm3). The desorption lifetimes and adsorption enthalpies inferred from the Langmuir adsorption constants suggest chemisorption of NO2 and O3 - possibly in the form of O atoms - and physisorption of H2O. The K2-SURF model enables the calculation of ozone uptake coefficients, γO3, and of PAH concentrations in the quasi-static particle surface layer. Competitive adsorption and chemical transformation of the surface (aging) lead to a strong non-linear dependence of γO3 on time and gas phase composition, with different characteristics under dilute atmospheric and concentrated laboratory conditions. Under typical ambient conditions, γO3 of PAH-coated aerosol particles are expected to be in the range of 10-6-10-5. At ambient temperatures, NO2 alone does not efficiently degrade PAHs, but it was found to accelerate the degradation of PAHs exposed to O3. The accelerating effect can be attributed to highly reactive NO3 radicals formed in the gas phase or on the surface. Estimated second-order rate coefficients for O3-NO2 and PAH-NO3 surface layer reactions are in the range of 10-17-10-16 cm2 s-1 and 10-15-10-12 cm2 s-1, respectively. The chemical half-life of PAH is expected to range from a few minutes on the surface of soot to multiple hours on organic and inorganic solid particles and days on liquid particles. On soot, the degradation of particle-bound PAHs in the atmosphere appears to be dominated by a surface layer reaction with adsorbed ozone. On other substrates, it is likely dominated by gas-surface reactions with OH or NO3 radicals (Eley-Rideal-type mechanism). To our knowledge, K2-SURF is the first atmospheric process model describing multiple types of parallel and sequential surface reactions between multiple gaseous and particle-bound chemical species. It illustrates how the general equations of the PRA framework can be simplified and adapted for specific reaction systems, and we suggest that it may serve as a basis for the development of a general master mechanism of aerosol and cloud surface chemistry.

  1. Aircraft Measurements of BrO, IO, Glyoxal, NO2, H2O, O2-O2 and Aerosol Extinction Profiles in the Tropics: Comparison with Aircraft-/Ship-Based in Situ and Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Volkamer, R.; Baidar, S.; Campos, T. L.; Coburn, S.; DiGangi, J. P.; Dix, B.; Eloranta, E. W.; Koenig, T. K.; Morley, B.; Ortega, I.; Pierce, B. R.; Reeves, M.; Sinreich, R.; Wang, S.; Zondlo, M. A.; Romashkin, P. A.

    2015-01-01

    Tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO2), water vapor (H2O) and O2-O2 collision complexes (O4/ were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAXDOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosol spectrometer (UHSAS) and in situ H2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/ National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCDREF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity-enhanced DOAS and MAX-DOAS. Inside the marine boundary layer (MBL) no BrO was detected (smaller than 0.5 pptv), and 0.2-0.55 pptv IO and 32-36 pptv glyoxal were observed. The near-surface concentrations agree within 30% (IO) and 10% (glyoxal) between ship and air-craft. The BrO concentration strongly increased with altitude to 3.0 pptv at 14.5 km (RF12, 9.1 to 8.6 deg N; 101.2 to 97.4 deg W). At 14.5 km, 5-10 pptv NO2 agree with model predictions and demonstrate good control over separating tropospheric from stratospheric absorbers (NO2 and BrO). Our profile retrievals have 12-20 degrees of freedom (DoF) and up to 500m vertical resolution. The tropospheric BrO vertical column density (VCD) was 1.5 x 10(exp 13) molec cm(exp -2) (RF12) and at least 0.5 x 10(exp 13) molec cm(exp -2) (RF17, 0- 10 km, lower limit). Tropospheric IO VCDs correspond to 2.1 x 10(exp 12) molec cm(exp -2) (RF12) and 2.5 x 10(exp 12) molec cm(exp -2) (RF17) and glyoxal VCDs of 2.6 x 10(exp 14) molec cm(exp -2) (RF12) and 2.7 x 10(exp 14) molec cm(exp -2) (RF17). Surprisingly, essentially all BrO as well as the dominant IO and glyoxal VCD fraction was located above 2 km (IO: 58 plus or minus 5 %, 0.1-0.2 pptv; glyoxal: 52 plus or minus 5 %, 3-20 pptv). To our knowledge there are no previous vertically resolved measurements of BrO and glyoxal from aircraft in the tropical free troposphere. The atmospheric implications are briefly discussed. Future studies are necessary to better understand the sources and impacts of free tropospheric halogens and oxygenated hydrocarbons on tropospheric ozone, aerosols, mercury oxidation and the oxidation capacity of the atmosphere.

  2. Identification of symmetry, structure and defects of dopant Mn(II) ions in Zn(C 3H 3O 4) 2(H 2O) 2 by single crystal EPR technique

    NASA Astrophysics Data System (ADS)

    Natarajan, B.; Mithira, S.; Sambasiva Rao, P.

    2008-12-01

    In order to understand the symmetry, structure and defects of Mn(II) impurity incorporated in diaquabis[malonato(1-)-κ 2O,O'] zinc(II), single crystal EPR studies have been carried out at X-band frequencies at room temperature. Angular variation in the three orthogonal planes shows the presence of two defects, having a relatively large and small zero-field splitting parameter ( D), with orthorhombic symmetry. The spin-Hamiltonian parameters, estimated from the three mutually orthogonal crystal rotations, are: Defect I:g xx = 1.959, g yy = 1.998, g zz = 2.011; A xx = -8.73, A yy = -8.55, A zz = -9.10 mT; D xx = 5.58, D yy = 1.33, D zz = -6.91 mT. Defect II:g xx = 2.015, g yy = 1.996, g zz = 2.004; A xx = -8.18, A yy = -8.00, A zz = -8.58 mT; D xx = 33.48, D yy = 6.92, D zz = -40.40 mT. The observed large zero-field tensor for Defect II is due to the steric effects caused by the two malonate rings. The location of the two interstitial defects has been determined from the X-ray data of the host lattice. The powder EPR spectrum also confirms the chemical inequivalence of the two defects. The optical absorption spectrum shows the characteristic of Mn(II) ions in distorted octahedral symmetry.

  3. Aircraft measurements of BrO, IO, glyoxal, NO2, H2O, O2-O2 and aerosol extinction profiles in the tropics: comparison with aircraft-/ship-based in situ and lidar measurements

    NASA Astrophysics Data System (ADS)

    Volkamer, R.; Baidar, S.; Campos, T. L.; Coburn, S.; DiGangi, J. P.; Dix, B.; Eloranta, E. W.; Koenig, T. K.; Morley, B.; Ortega, I.; Pierce, B. R.; Reeves, M.; Sinreich, R.; Wang, S.; Zondlo, M. A.; Romashkin, P. A.

    2015-05-01

    Tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO2), water vapor (H2O) and O2-O2 collision complexes (O4) were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosol spectrometer (UHSAS) and in situ H2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCDREF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity-enhanced DOAS and MAX-DOAS. Inside the marine boundary layer (MBL) no BrO was detected (smaller than 0.5 pptv), and 0.2-0.55 pptv IO and 32-36 pptv glyoxal were observed. The near-surface concentrations agree within 30% (IO) and 10% (glyoxal) between ship and aircraft. The BrO concentration strongly increased with altitude to 3.0 pptv at 14.5 km (RF12, 9.1 to 8.6° N; 101.2 to 97.4° W). At 14.5 km, 5-10 pptv NO2 agree with model predictions and demonstrate good control over separating tropospheric from stratospheric absorbers (NO2 and BrO). Our profile retrievals have 12-20 degrees of freedom (DoF) and up to 500 m vertical resolution. The tropospheric BrO vertical column density (VCD) was 1.5 x 1013 molec cm-2 (RF12) and at least 0.5 x 1013 molec cm-2 (RF17, 0-10 km, lower limit). Tropospheric IO VCDs correspond to 2.1 x 1012 molec cm-2 (RF12) and 2.5 x 1012 molec cm-2 (RF17) and glyoxal VCDs of 2.6 x 1014 molec cm-2 (RF12) and 2.7 x 1014 molec cm-2 (RF17). Surprisingly, essentially all BrO as well as the dominant IO and glyoxal VCD fraction was located above 2 km (IO: 58 ± 5%, 0.1-0.2 pptv; glyoxal: 52 ± 5%, 3-20 pptv). To our knowledge there are no previous vertically resolved measurements of BrO and glyoxal from aircraft in the tropical free troposphere. The atmospheric implications are briefly discussed. Future studies are necessary to better understand the sources and impacts of free tropospheric halogens and oxygenated hydrocarbons on tropospheric ozone, aerosols, mercury oxidation and the oxidation capacity of the atmosphere.

  4. Structure vs. composition: A solid-state 1H and 29Si NMR study of quenched glasses along the Na 2O-SiO 2-H 2O join

    NASA Astrophysics Data System (ADS)

    Cody, George D.; Mysen, Bjorn O.; Lee, Sung Keun

    2005-05-01

    A suite of six hydrous (7 wt.% H 2O) sodium silicate glasses spanning sodium octasilicate to sodium disilicate in composition were analyzed using 29Si single pulse (SP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, 1H- 29Si cross polarization (CP) MAS NMR, and fast MAS 1H-NMR. From the 29Si SPMAS data it is observed that at low sodium compositions dissolved water significantly depolymerizes the silicate network. At higher sodium contents, however, dissolved H 2O does not affect a significant increase in depolymerization over that predicted based on the Na/Si ratio alone. The fast MAS 1H-NMR data reveal considerable complexity in proton environments in each of the glasses studied. The fast MAS 1H-NMR spectra of the highest sodium concentration glasses do not exhibit evidence of signficantly greater fractions of dissolved water as molecular H 2O than the lower sodium concentration glasses requiring that the decrease in polymerization at high sodium contents involves a change in sodium solution mechanism. Variable contact time 1H- 29Si cross polarization (CP) MAS NMR data reveal an increase in the rotating frame spin lattice relaxation rate constant ( T1ρ*) for various Q n species with increasing sodium content that correlates with a reduction in the average 1H- 29Si coupling strength. At the highest sodium concentration, however, T1ρ* drops significantly, consistent with a change in the Na 2O solution mechanism.

  5. Heat capacities and entropies from 8 to 1000 K of langbeinite (K2Mg2(SO4)3), anhydrite (CaSO4) and of gypsum (CaSO4·2H2O)

    USGS Publications Warehouse

    Robie, Richard A.; Russell-Robinson, Susan; Hemingway, Bruce S.

    1989-01-01

    Although Bond (Bell Sys. Tech. J., 22 (1943) 145) reported that langbeinite was piezoelectric at room temperature, we found no evidence in our Cpo measurements for a Curie temperature above which langbeinite would no longer be piezoelectric.

  6. Structural characterization of self-assembled ZnO nanoparticles obtained by the sol-gel method from Zn(CH3COO)2·2H2O.

    PubMed

    Luković Golić, D; Branković, G; Počuča Nešić, M; Vojisavljević, K; Rečnik, A; Daneu, N; Bernik, S; Sćepanović, M; Poleti, D; Branković, Z

    2011-09-30

    Zinc oxide nanopowders were synthesized by the sol-gel method from an ethanol solution of zinc acetate dihydrate. Detailed structural and microstructural investigations were carried out using x-ray diffraction, Raman spectroscopy, thermogravimetric and differential thermal analyses, as well as high-resolution transmission electron microscopy (TEM) and field-emission scanning electron microscopy. The intermediate compound of the reaction was layered zinc hydroxide acetate that further transforms into hexagonally shaped ZnO crystalline nanoplates (d(m) = 4 nm), which aggregate into larger spherical particles. According to the TEM analysis the ZnO nanoparticles were self-assembled into larger particles with the same orientation, i.e. aligned lattice planes of the particles. A further solvothermal treatment resulted in hexagonal, prismatic ZnO mesocrystals.

  7. Isopiestic Determination of the Osmotic and Activity Coefficients of NaCl + SrCl2 + H2O at 298.15 K, and Representation with an Extended Ion-Interaction Model

    SciTech Connect

    Clegg, S L; Rard, J A; Miller, D G

    2004-11-09

    Isopiestic vapor-pressure measurements were made at 298.15 K for aqueous NaCl + SrCl{sub 2} solutions, using NaCl(aq) as the reference standard. The measurements for these ternary solutions were made at NaCl ionic strength fractions of y{sub 1} = 0.17066, 0.47366, and 0.82682 for the water activity range 0.9835 {ge} a{sub w} {ge} 0.8710. Our results, and those from two previous isopiestic studies, were combined and used with previously determined parameters for NaCl(aq) and those for SrCl{sub 2}(aq) determined here to evaluate the mixing parameters{sup S}{Theta}{sub Na,Sr} = (0.0562 {+-} 0.0007) kg {center_dot} mol{sup -1} and {Psi}{sub Na,Sr,Cl} = -(0.00705 {+-} 0.00017) kg{sup 2} {center_dot} mol{sup -2} for an extended form of Pitzer's ion-interaction model. These model parameters are valid for ionic strengths of I {le} 7.0 mol {center_dot} kg{sup -1}, where higher-order electrostatic effects have been included in the mixture model. If the fitting range is extended to the saturated solution molalities, then {sup S}{Theta}{sub Na,Sr} = (0.07885 {+-} 0.00195) kg {center_dot} mol{sup -1} and {Psi}{sub Na,Sr,Cl} = -(0.01230 {+-} 0.00033) kg{sup 2} {center_dot} mol{sup -2}. The extended ion-interaction model parameters obtained from available isopiestic data for SrCl{sub 2}(aq) at 298.15 K yield recommended values of the water activities and osmotic and activity coefficients.

  8. Synergistic sterilization effect of microwave-excited nonthermal Ar plasma, H2O2, H2O and TiO2, and a global modeling of the interactions

    NASA Astrophysics Data System (ADS)

    Lee, H. Wk; Lee, H. W.; Kang, S. K.; Y Kim, H.; Won, I. H.; Jeon, S. M.; Lee, J. K.

    2013-10-01

    A microwave-excited atmospheric-pressure plasma jet (uAPPJ) exhibited a synergistic sterilization effect when combined with hydrogen peroxide (H2O2), distilled water (DW) and titanium dioxide (TiO2) photocatalysis. The sterilization efficacy of H2O2-uAPPJ increased as the H2O2 concentration increased. The addition of TiO2 also remarkably increased the sterilization efficacy. To find the main factor for the sterilization effect, optical emission spectra and the degradation rate of a methylene blue solution were measured. Numerical analysis, a newly developed global modeling, was also conducted to discover the mechanisms. Both experimental measurements and global modeling results suggested that combinations of H2O2, DW and TiO2 increased the generation of hydroxyl radicals (·OH), which are known to be strong bactericidal agents. It was revealed that charged species, especially electrons, have a dominant role in the increase of ·OH.

  9. Optimizing Synthesis of Na2Ti2SiO7 - 2H2O (Na-CST) and Ion Exchange Pathways for Cs0.4H1.6Ti2SiO7 - H2O (Cs-CST) Determined from in situ Synchrotron X-ray Powder Diffraction

    SciTech Connect

    Celestian,A.; Medvedev, D.; Tripathi, A.; Parise, J.; Clearfield, A.

    2005-01-01

    Observation of wide angle diffraction data collected in situ during previous synthesis of Na-CST (Na{sub 2}Ti{sub 2}SiO{sub 7}-2H{sub 2}O) showed initial crystallization of a precursor phase (SNT) at 30 C followed by conversion to CST after 1 h at 220 C. In situ studies of Cs{sup +} ion exchange into the H{sup +} form of CST showed a site-by-site ion exchange pathway accompanied by a simultaneous structural transition from P4{sub 2}/mbc (cell parameters a = 11.0690(6) Angstroms, c = 11.8842(6) Angstroms) to P4{sub 2}/mcm (cell parameters a = 7.847(2) Angstroms, c = 11.9100(6) Angstroms). After approximately 18% Cs{sup +} exchange into site designated Cs2 in space group P4{sub 2}/mcm, a site designated Cs1 in space group P4{sub 2}/mcm began to fill at the center of the 8MR windows until a maximum of approximately 22% exchange was achieved for Cs1. Bond valence sums of site Cs1 to framework O{sup 2-} are 1.00 v.u., while bond valence sums of site Cs2 to framework O{sup 2-} are 0.712 v.u. suggesting Cs1 to have a more stable bonding environment.

  10. The Product of the reaction of [Co(en) 2( N, S Bound-( R)cystein)] 2+ with CH 2l 2 in DMSO solution: [Co(en) 2( N, S-bound- S-iodomethyl-( R)cystein)]Cl 3·2H 2O( 1)

    NASA Astrophysics Data System (ADS)

    Cai, Jiwen; Bernal, Ivan; Gregory Jackson, W.

    1998-10-01

    ( 1), ICOCl 3SO 4N 5C 8H 25- N, S, was prepared by the reaction of diiodomethane with the [Co(en) 2( R)cysteinato- N, S] 2+ cation in DMSO solution. It crystallizes in space group P2 1 (no. 4) with lattice constants of a=11.914(3), b=12.714(4), c=14.573(4) Å, β=107.79(2)°; V=2101.83 A 3 and d(calc; MW=577.55, z=4)=1.825 g cm -3. A total of 2178 data were collected over the range of 4°≤2θ≤50° of these, 1778 [independent and with I≥3σ( I)] were used in the structural analysis. Data were corrected for absorption(μ=40.3 cm -1) and the transmission coefficients ranged from 0.5862 to 0.8357. The correct enantiomorph was determined by the method of Flack. For ( 1), the two cations in the asymmetric unit were found to be Co1=Λ(λδλ) and Co2=Λ(λλλ), where the last symbol in parenthesis defines the helical chirality at the cystein ring; the -COOH substituent is equatorially disposed in both cations. The configurations of the alkylated sulfur centers and the asymmetric carbons of the cystein ligands for both metal cations are, respectively, S and R; the latter is the natural configuration for cystein.

  11. Synthetic gedrite: a stable phase in the system MgO-Al2O3-SiO2-H2O (MASH) at 800°C and 10kbar water pressure, and the influence of FeNaCa impurities

    NASA Astrophysics Data System (ADS)

    Fischer, H.; Schreyer, W.; Maresch, W. V.

    Seeded, solid-media piston-cylinder runs of unusually long duration up to 31 days indicate growth or persistence of synthetic gedrite of the composition □Mg6Al[AlSi7O22](OH)2(=6:1:7), prepared from the purest chemicals available, at 10kbar water pressure and 800°C. Conversely, breakdown was observed at 11kbar and 850°C to aluminous enstatite, Al2SiO5, and a melt of the composition MgO.Al2O3.8SiO2. Thus, pure gedrite free of iron, sodium, and calcium is likely to have only a small PT stability field in the MASH system, estimated as 10+/-1kbar, 800+/-20°C, even though metastable growth of gedrite can be observed over a larger PT range. A second starting material with the anhydrous composition 5MgO . 2Al2O3 . 6SiO2 also yielded gedrite of the composition 6:1:7, together with more aluminous phases such as kyanite, corundum or sapphirine, thus suggesting that the end-member gedrite defined as □Mg5Al2[Al2Si6O22](OH)2(=5:2:6) by the IMA Commission on New Minerals and Mineral Names probably does not exist. With the use of this second starting material, which contains FeNaCa impurities, growth of 6:1:7-gedrite was observed over a still wider PT-range. Seeded runs indicate that the true stability field of such slightly impure 6:1:7-gedrites may also be larger than that of the pure MASH phase and extend at least to 15kbar, 800°C. There is, thus, a remarkable stabilization effect on the orthoamphibole structure by impurities amounting only to a total of less than one weight percent of oxides in the starting material. The gedrites synthesized are structurally well ordered amphiboles nearly free of chain multiplicity faults, as revealed by HRTEM. The X-ray diffraction work on the gedrites synthesized yielded the smallest cell volume yet reported for this phase. The small stability field of the pure MASH gedrite is intersected by the upper pressure stability limit of hydrous cordierite for excess-H2O conditions, thus leading to complicated phase relations for both gedrite and cordierite involving the additional phases aluminous enstatite, talc, quartz, Al2SiO5, melt and perhaps boron-free kornerupine.

  12. The solubility of BaCO3(cr) (witherite) in CO2-H2O solutions between 0 and 90°C, evaluation of the association constants of BaHCO3+(aq) and BaCO30(aq) between 5 and 80°C, and a preliminary evaluation of the thermodynamic properties of Ba2+(aq)

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    1986-01-01

    Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of ΔfH° and ΔfG° of Ba2+(aq) to −532.5 and −555.36 kJ · mol−1, respectively, for agreement with solubility data.

  13. The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

    NASA Astrophysics Data System (ADS)

    Iannarelli, R.; Rossi, M. J.

    2015-11-01

    Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

  14. Study of Cross-Linking Density and the Type of Cross Linkage in Polyurethane Elastomers (Sintez i Fiziko-Khimiya Poliuretanov),

    DTIC Science & Technology

    2014-09-26

    Ya, ya ye initially, after vowels, and after u, b; e elsewhere. When written as 9 in Russian , transliterate as yf or 9. RUSSIAN AND ENGLISH...TRIGONOMETRIC FUNCTIONS Russian English Russian English Russian English sin sin sh sinh arc sh snh-1 cos cos ch cosh arc ch cosh-1tg tan th tanh arc .th tanh...1ctg cot cth coth arc cth coth 1sec sec sch sech arc sch sech-.I cosec casc csch csch arc csch csch Russian English 0 0 rot curl - lg log GRAPHICS

  15. [Polonia Medyczna: struktura, współczesność i przyszłość].

    PubMed

    Rudnicki, Marek

    It is estimated that approximately 20-25 000 polish physicians practice medicine in different countries outside of Poland, enriching medical workforces in their newly elected countries. The composition of this group, known as "Medical Polonia", has been changing from post Second World War emigration, resulting from the war and its political consequences, thru the next large wave of physicians leaving the communist country in 1980's. The last large group of Polish physicians has taken advantage of training opportunities or have started practices in the European Union, having departed Poland permanently or temporarily, after the country joined the European Union in 2004. The first organizations of Polish physicians outside of Poland were founded almost immediately after WWII in London, Chicago, New York, Paris, Lille, and later in Stockholm. Decades later, re-invigorated by their native country gaining independence after 1989, they organized the first World Congress of Medical Polonia in 1991 (in collaboration with physicians' organization from Poland). The World Federation of Polish Medical Organization Abroad was then established in 1994. Subsequently, many organizations joined the Federation, including several from newly liberated countries of former Soviet Union. The Federation of Polish Medical Organizations and its member societies actively promotes medical education, collaboration between polish doctors all over the world, and the exchange of ideas-sharing experiences with significant emphasis on the quality of care and patient safety.

  16. The solubility of strontianite (SrCO3) in CO2-H2O solutions between 2 and 91°C, the association constants of SrHCO+3(aq) and SrCO03(aq) between 5 and 80°C, and an evaluation of the thermodynamic properties of Sr2+(aq) and SrCO3(cr) at 25°C and 1 atm total pressure

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Neil; Parker, Vivian B.

    1984-01-01

    Our new data for strontianite have been used in an evaluation of the thermodynamic properties of Sr2+(aq), SrCO3(cr) and related compounds. The following values are recommended for the standard enthalpy (kJ · mol−1), Gibbs energy (kJ · mol−1), and entropy (J · mol−1 · K−1), respectively, of Sr2+aq): −550.90 ± 0.50, −563.83 ± 0.8 and −31.50 ± 2.0, and for SrCO3(cr): −1225.77 ± 1.1, −1144.73 ± 1.0 and 97.2.

  17. Financial Structure of Mining Sector Companies During an Economic Slowdown /Struktura Finansowania Przedsiębiorstw W Sektorze Górniczym I Wydobywczym W Okresie Spowolnienia Gospodarczego

    NASA Astrophysics Data System (ADS)

    Sierpińska, Maria; Bąk, Patrycja

    2012-12-01

    The global economic crisis that started in 2007 in the area of finance, expanded over the subsequent years to the business sphere, and resulted in a drop of demand and production almost in any field of business activity. Access to foreign sources of finance, especially to loans, has become more difficult and expensive. In such circumstances, enterprises have had to resort more often to their own capital generated by the issue of shares, and to retained profit. Banks have limited their loans for business entities, reduced credit periods, and raised credit margins as well as their levels of collaterals. The McKinsey research into the changes that occur in the structures of sources of finance confirms that the share of equity capital in the structure of financing of non-financial enterprises has visibly grown, and their crediting scopes have been limited all over the European Union as well as in the euro zone. The global tendencies as regards directions of changes in the structure of the sources of corporate financing have also been reflected in Poland. The economic slowdown has resulted in changes in the structures of corporate financing. Mining companies have risen the shares of their equity capital in their general sources of financing. This tendency corresponds to the changes of structure of corporate financing in Poland and Europe. Enterprises have resorted to bank loans to a lesser degree than in times of better market situation. In mining, public companies have increased their crediting, while in private sector the tendency has been reverse. Enterprises tend to use more flexible debiting forms as compared to credits by way of issue of long-term corporate bonds. Mining companies have developed issue programs that are to be implemented over three-year periods. Before, only Katowicki Holding Węglowy [Katowice Mining Holding] had issued bonds. The present publication is an attempt at assessing the changes in the structure of corporate financing within the mining sector in the circumstances of economic slowdown. The changes have been assessed against the background of changes in the structure of financing of other business entities. Three problems have been identified and subjected to research. The first concerns the increasing share of equity capital in the structure of corporate financing in mining enterprises. The second issue concerns the scope of corporate crediting. And the third issue relates to the time structure of corporate debt. The said issues have been analysed in the conditions of economic slowdown

  18. Uncloaking the thermodynamics of the studtite to metastudtite shear-induced transformation

    DOE PAGES

    Weck, Philippe F.; Kim, Eunja

    2016-07-11

    The interplay between thermodynamics and mechanical properties in the transformation of studtite, (UO2)(O2)(H2O)2·2H2O, into metastudtite, (UO2)(O2)(H2O)2, two important corrosion phases observed on the surface of uranium dioxide exposed to water, is revealed using density functional perturbation theory. Phonon calculations within the quasi-harmonic approximation predict that the standard entropy change for the (UO2)(O2)(H2O)2·2H2O → (UO2)(O2)(H2O)2 + 2H2O reaction is ΔS0 = +80 J·mol–1·K–1 for the production of water in the liquid state and +389 J·mol–1·K–1 for water vapor. Similar to bulk H2O(l), the bulk modulus of (UO2)(O2)(H2O)2·2H2O increases with temperature, contrasting with (UO2)(O2)(H2O)2 which features the typical Anderson–Gruneisen temperature dependence ofmore » oxide solids. Upon removal of interstitial H2O in studtite, the most important changes in the shear modulus, the parameter limiting the mechanical stability, arise in the planes normal to chain propagation directions. Lastly, the present findings have important implications for the dehydration of other hygroscopic materials.« less

  19. Coordination polymers of 5-substituted isophthalic acid† †Electronic supplementary information (ESI) available. CCDC 1417516–1417520 contain the supplementary crystallographic data for this paper. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ce02091c Click here for additional data file. Click here for additional data file.

    PubMed Central

    Morris, Samuel A.; Slawin, Alexandra M. Z.; Teat, Simon J.; Morris, Russell E.

    2016-01-01

    The synthesis and characterisation of five coordination polymers – Ni2(mip)2(H2O)8·2H2O (1), Zn6(mip)5(OH)2(H2O)4·7.4H2O (2), Zn6(mip)5(OH)2(H2O)2·4H2O (3), Mn(HMeOip)2 (4), and Mn3(tbip)2(Htbip)2(EtOH)2 (5) – are reported. Preliminary nitric oxide release data on compounds 2 and 3 are also given. PMID:27019640

  20. On the mechanical stability of uranyl peroxide hydrates: Implications for nuclear fuel degradation

    SciTech Connect

    Weck, Philippe F.; Kim, Eunja; Buck, Edgar C.

    2015-09-11

    The mechanical properties and stability of studtite, (UO2)(O2)(H2O)2·2H2O, and metastudtite, (UO2)(O2)(H2O)2, two important corrosion phases observed on spent nuclear fuel exposed to water, have been investigated using density functional perturbation theory. While (UO2)(O2)(H2O)2 satisfies the necessary and sufficient Born criteria for mechanical stability, (UO2)(O2)(H2O)2·2H2O is found to be mechanically metastable, which might be the underlying cause of the irreversibility of the studtite to metastudtite transformation. According to Pugh’s and Poisson’s ratios and the Cauchy pressure, both phases are considered ductile and shear modulus is the parameter limiting their mechanical stability. Debye temperatures of 294 and 271 K are predicted for polycrystalline (UO2)(O2)(H2O)2·2H2O and (UO2)(O2)(H2O)2, suggesting a lower micro-hardness of metastudtite.

  1. On the mechanical stability of uranyl peroxide hydrates: Implications for nuclear fuel degradation

    DOE PAGES

    Weck, Philippe F.; Kim, Eunja; Buck, Edgar C.

    2015-09-11

    The mechanical properties and stability of studtite, (UO2)(O2)(H2O)2·2H2O, and metastudtite, (UO2)(O2)(H2O)2, two important corrosion phases observed on spent nuclear fuel exposed to water, have been investigated using density functional perturbation theory. While (UO2)(O2)(H2O)2 satisfies the necessary and sufficient Born criteria for mechanical stability, (UO2)(O2)(H2O)2·2H2O is found to be mechanically metastable, which might be the underlying cause of the irreversibility of the studtite to metastudtite transformation. According to Pugh's and Poisson's ratios and the Cauchy pressure, both phases are considered ductile and shear modulus is the parameter limiting their mechanical stability. Furthermore, debye temperatures of 294 and 271 K are predictedmore » for polycrystalline (UO2)(O2)(H2O)2·2H2O and (UO2)(O2)(H2O)2, suggesting a lower micro-hardness of metastudtite.« less

  2. Various ferroic orderings of triclinic tetrachloro-metallate dihydrate crystals.

    PubMed

    Tylczyński, Z; Członkowska, M; Laniecki, M

    2009-03-11

    In the triclinic crystals Rb(2)MnCl(4)·2H(2)O, Cs(2)MnCl(4)·2H(2)O and Cs(2)CaCl(4)·2H(2)O the ferroelastic domain structure has been observed for temperatures from 100 K to the dehydration point. On heating at a few degrees before the dehydration point the structure has been found to reorganize. On heating in Rb(2)MnCl(4)·2H(2)O and Cs(2)MnCl(4)·2H(2)O (but not in Cs(2)CaCl(4)·2H(2)O) a dielectric anomaly typical of a weak ferroelectric phase transition has been noted. The low-frequency dielectric dispersion in the low-temperature phase is attributed to the oscillations of the domain walls. The activation energy of this motion is 73 and 67 kJ mol(-1) in Rb(2)MnCl(4)·2H(2)O and Cs(2)MnCl(4)·2H(2)O, respectively. In the phase transition region the complex permittivity has been found to show oscillations as a function of temperature.

  3. The contribution of molecular relaxation in nitrogen to the absorption of sound in the atmosphere

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Meredith, R. W.

    1980-01-01

    Results and statistical analysis are presented for sound absorption in N2-H2O binary mixtures at room temperature. Experimental procedure, temperature effects, and preliminary results are presented for sound absorption in N2-H2O binary mixtures at elevated temperatures.

  4. Single-crystal to single-crystal transformations in discrete hydrated dimeric copper complexes.

    PubMed

    Mobin, Shaikh M; Srivastava, Ashwini K; Mathur, Pradeep; Lahiri, Goutam Kumar

    2010-02-14

    The single crystals of discrete hydrated [(OAc)Cu(mu-hep)(2)Cu(OAc)].2H(2)O (.2H(2)O) and [(OAc)Cu(mu-hep)(2) Cu(O(n)Pr)].2H(2)O (.2H(2)O) (the lattice H(2)O molecules exist as a tetrameric water cluster, hep-H = 2-(2-hydroxyethyl)pyridine), OAc(-) = acetate and O(n)Pr(-) = n-propionate) undergo single-crystal to single-crystal (SCSC) transformations to the dehydrated and , respectively, under the influence of heat. The reverse SCSC processes of /-->.2H(2)O/.2H(2)O involving the regeneration of the lattice water tetramers take place on exposure of / to water vapour. However, the blue single crystal of discrete hydrated [(O(n)Pr)Cu(mu-hep)(2)Cu(O(n)Pr)].2H(2)O (.2H(2)O), incorporating the two bulkier O(n)Pr(-) terminal bidentate ligands, irreversibly converts to the green single crystal of a unique discrete tetrameric [Cu(4)(mu(3)hep)(2)(mu-hep)(2)(mu-O(n)Pr)(2)(O(n)Pr)(2)] () with double open cubane core either by heating or by a simple vapour diffusion technique via the breaking and forming of multiple covalent bonds.

  5. SOVRaD - A Digest of Recent Soviet R and D Articles. Volume 2, Number 5, 1976

    DTIC Science & Technology

    1976-05-01

    emission current from the electron gun as well as by pulsations of accelerating voltage and currents in the magnetic system of the gun . Analogous waves...flows). Novosibirsk, Izd-vo Nauka, Sib. otd-ye, 1975, 168 p. Luk’yanov, S. Yu. Goryachaya plazma i upravlyayemyy yadernyy sintez

  6. Binding energies for the inner hydration shells of Ca2+

    NASA Astrophysics Data System (ADS)

    Carl, Damon R.; Moision, Robert M.; Armentrout, P. B.

    2007-09-01

    The sequential bond energies of Ca2+(H2O)x complexes, where x = 5-9, are determined by collision-induced dissociation (CID) using a guided ion beam tandem mass spectrometer with a recently developed electrospray ionization source. To our knowledge, this represents the first quantitative threshold CID study of multiply charged ions. The kinetic energy dependent cross sections are determined over a wide energy range to monitor all possible dissociation products and are modeled to obtain 0 and 298 K binding energies for loss of a single water molecule. These binding energies decrease monotonically for the Ca2+(H2O)5 complex to Ca2+(H2O)7 and plateau for Ca2+(H2O)7, Ca2+(H2O)8, and Ca2+(H2O)9. This suggests that six water molecules bind directly to the calcium ion and that three outer shell water molecules bind to inner shell water molecules through similar binding motifsE Our experimental results agree well with previous literature results obtained by equilibrium and BIRD studies. We also present an in-depth theoretical study of the structures and energetics of the Ca2+(H2O)x systems, employing several levels of theory. The present theoretical results focus on the larger hydrates (x = 8 and 9) where multiple low lying conformations are possible and there is little previous theory.

  7. Thermodynamics of oxygen activation by macrocyclic complexes of rhodium.

    PubMed

    Szajna-Fuller, Ewa; Bakac, Andreja

    2007-12-10

    The oxidation of ABTS2- [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate)] with a superoxorhodium(III) complex, L2(H2O)RhOO2+ (L2 = meso-hexamethylcyclam) is characterized by an acid-dependent equilibrium constant, log(Ke/[H+]) = 4.91 +/- 0.10 in the pH range of 4.89-6.49. This equilibrium constant was used to calculate the reduction potential for the L2(H2O)RhOO2+/L2(H2O)RhOOH2+ couple, E0 = 0.97 V vs NHE. The pH dependence of the kinetics of the L2(H2O)RhOOH2+/I- reaction yielded the acid dissociation constant for the coordinated water in L2(H2O)RhOOH2+, pKa = 6.9. Spectrophotometric pH titrations provided pKa = 6.6 for the superoxo complex, L2(H2O)RhOO2+. The combination of the two pKa values with the reduction potential measured in acidic solutions yielded the reduction potential E0 = 0.95 V for the L2(HO)RhOO+/L2(HO)RhOOH+ couple. Thermochemical calculations yielded the bond-dissociation free energy of the L2(H2O)RhOO-H2+ bond as 315 kJ/mol at 298 K.

  8. Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. X. thermal stability and dehydration features of synthetic analogs of the cobaltomenite-ahlfeldite solid solution series

    NASA Astrophysics Data System (ADS)

    Charykova, M. V.; Fokina, E. L.; Krivovichev, V. G.; Yakovenko, O. S.; Klimova, E. V.; Semenova, V. V.

    2015-12-01

    The aim of this study is the experimental investigation of the synthetic analogs of cobaltomenite, CoSeO3 • 2H2O, ahlfeldite, NiSeO3 • 2H2O, members of the cobaltomenite-ahlfeldite solid solution series (Ni x Co1- x )SeO3 • 2H2O, and singularities of their dehydration and dissociation. The intermediate members of the cobaltomenite (CoSeO3 • 2H2O)-ahlfeldite (NiSeO3 • 2H2O) series have been synthesized and studied with a combination of X-ray diffraction, scanning electron microscopy, and the simultaneous application of thermogravimetry (TG) and differential scanning calorimetry (DSC) within the temperature range from 25 to 640°C. The complete solid solution series corresponds to the monoclinic space group P21/ n. Unit-cell dimensions decrease in all crystallographic directions as the amount of Ni increases. The angle β increases from 98.82(1) (cobaltomenite) to 99.05(1)° (ahlfeldite). It has been established that CoSeO3 • 2H2O and NiSeO3 • 2H2O dehydrate at 120-340°C through two stages apparently corresponding, to the formation of intermediate hydrated species CoSeO3 • H2O and NiSeO3 • 1/3H2O. The reaction enthalpies for each dehydration stage of CoSeO3 • 2H2O and NiSeO3 • 2H2O have been determined. Changes of the unit-cell dimensions and dehydration temperatures are rationalized in terms of the Co and Ni site occupancy in the structure of the cobaltomenite-ahlfeldite solid-solution series members.

  9. Microwave spectra of van der Waals complexes of importance in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Suenram, R. D.; Lovas, F. J.

    1990-01-01

    The Fourier-transform Fabry-Perot pulsed-molecular-beam microwave spectrometer at NIST was used to study the microwave spectra of a number of molecular dimers and trimers that may be present in planetary atmospheres. The weak van der Waals bonds associated with these species usually give rise to rotational-tunneling splittings in the microwave spectra. The microwave spectrum of the water dimer species was used to illustrate the complications that can arise in the study of the rotational spectra of these loosely bound species. In addition to the water dimer species, the microwave spectra of the following hydrogen-bonded and van der Waals complexes were studied: (CO2)2-H2O, CO2-(H2O)2, CO2-H2S, N2-H2O, CO-H2O, SO2-H2O, and O3-H2O.

  10. 21 CFR 184.1845 - Stannous chloride (anhydrous and dihydrated).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... chlorine or gaseous tin tetrachloride. Dihydrated stannous chloride (SnCl2·2H2O, CAS Reg. No. 10025-69-1... granulated tin suspended in water and hydrochloric acid or chlorine. (b) Both forms of the ingredient...

  11. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

  12. Heterometallic Metal-Organic Frameworks That Catalyze Two Different Reactions Sequentially.

    PubMed

    Saha, Debraj; Hazra, Dipak K; Maity, Tanmoy; Koner, Subratanath

    2016-06-20

    A series of copper- and alkaline-earth-metal-based multidimensional metal-organic frameworks, {[CuMg(pdc)2(H2O)4]·2H2O}n (1), [CuCa(pdc)2]n (2), [CuSr(pdc)2(H2O)3]n (3), and {[CuBa(pdc)2(H2O)5]·H2O}n (4), where H2Pdc = pyridine-2,5-dicarboxylic acid, were hydrothermally synthesized and characterized. Two different metals act as the active center to catalyze two kinds of reactions, viz., olefin to its epoxide followed by epoxide ring opening to afford the corresponding vicinal diol in a sequential manner.

  13. Thermodynamic fundamentals of ferrous cake sulfitization

    NASA Astrophysics Data System (ADS)

    Tyurin, A. G.; Vasekha, M. V.; Biryukov, A. I.

    2016-03-01

    The Pourbaix diagrams of the systems SO 4 2- -SO 3 2- -H2O and iron hydroxide (oxide)-H2O are refined. The E(pH) dependence of the sulfitization of iron(III) hydroxide is refined with allowance for the regions of predominant phase constituents of the systems. The potential E-pH electrochemical equilibrium diagrams of the systems Fe(OH)3-H2SO4-SO 3 2- -H2O, FeOOH-H2SO4-SO 3 2- -H2O, and Fe2O3-H2SO4-SO 3 2- -H2O are plotted. These diagrams can be considered as a thermodynamic basis for the sulfite conversion of the ferrous cake of copper-nickel production.

  14. Synthesis and spectroscopic studies of iron (III) complex with a quinolone family member (pipemidic acid)

    NASA Astrophysics Data System (ADS)

    Skrzypek, D.; Szymanska, B.; Kovala-Demertzi, Dimitra; Wiecek, Joanna; Talik, E.; Demertzis, Mavroudis A.

    2006-12-01

    The interaction of iron (III) with pipemidic acid, Hpipem, afforded the complex [Fe (pipem) (HO)2 (H2O)]2. The new complex has been characterised by elemental analyses, infra-red, EPR and XPS spectroscopies. The monoanion, pipem, exhibits O, O ligation through the carbonyl and carboxylato oxygen atoms. Six coordinate dimer distorted octahedral configuration has been proposed for [Fe (pipem) (HO)2 (H2O)]2.

  15. Effect of persulfate and persulfate/H₂O₂ on biodegradability of an anaerobic stabilized landfill leachate.

    PubMed

    Hilles, Ahmed H; Abu Amr, Salem S; Hussein, Rim A; Arafa, Anwar I; El-Sebaie, Olfat D

    2015-10-01

    The current study investigated the effects of S2O8(2-) and S2O8(2-)/H2O2 oxidation processes on the biodegradable characteristics of an anaerobic stabilized leachate. Total COD removal efficiency was found to be 46% after S2O8(2-) oxidation (using 4.2 g S2O8(2-)/1g COD0, at pH 7, for 60 min reaction time and at 350 rpm shaking speed), and improved to 81% following S2O8(2-)/H2O2 oxidation process (using 5.88 g S2O8(2-) dosage, 8.63 g H2O2 dosage, at pH 11 and for 120 min reaction time at 350 rpm). Biodegradability in terms of BOD5/COD ratio of the leachate enhanced from 0.09 to 0.1 and to 0.17 following S2O8(2-) and S2O8(2-)/H2O2 oxidation processes, respectively. The fractions of COD were determined before and after each oxidation processes (S2O8(2-) and S2O8(2-)/H2O2). The fraction of biodegradable COD(bi) increased from 36% in raw leachate to 57% and 68% after applying S2O8(2-) and S2O8(2-)/H2O2 oxidation, respectively. As for soluble COD(s), its removal efficiency was 39% and 78% following S2O8(2-) and S2O8(2-)/H2O2 oxidation, respectively. The maximum removal for particulate COD was 94% and was obtained after 120 min of S2O8(2-)/H2O2 oxidation. As a conclusion, S2O8(2-)/H2O2 oxidation could be an efficient method for improving the biodegradability of anaerobic stabilized leachate.

  16. Hydration of potassium iodide dimer studied by photoelectron spectroscopy and ab initio calculations

    NASA Astrophysics Data System (ADS)

    Li, Ren-Zhong; Zeng, Zhen; Hou, Gao-Lei; Xu, Hong-Guang; Zhao, Xiang; Gao, Yi Qin; Zheng, Wei-Jun

    2016-11-01

    We measured the photoelectron spectra of (KI)2-(H2O)n (n = 0-3) and conducted ab initio calculations on (KI)2-(H2O)n anions and their corresponding neutrals up to n = 6. Two types of spectral features are observed in the experimental spectra of (KI)2-(H2O) and (KI)2-(H2O)2, indicating that two types of isomers coexist, in which the high EBE feature corresponds to the hydrated chain-like (KI)2- while the low EBE feature corresponds to the hydrated pyramidal (KI)2-. In (KI)2-(H2O)3, the (KI)2- unit prefers a pyramidal configuration, and one of the K-I distances is elongated significantly, thus a K atom is firstly separated out from the (KI)2- unit. As for the neutrals, the bare (KI)2 has a rhombus structure, and the structures of (KI)2(H2O)n are evolved from the rhombus (KI)2 unit by the addition of H2O. When the number of water molecules reaches 4, the K-I distances have significant increment and one of the I atoms prefers to leave the (KI)2 unit. The comparison of (KI)2(H2O)n and (NaI)2(H2O)n indicates that it is slightly more difficult to pry apart (KI)2 than (NaI)2 via hydration, which is in agreement with the lower solubility of KI compared to that of NaI.

  17. Volume properties and refraction of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids lysine, threonine, and oxyproline (C60(C6H13N2O2)2, C60(C4H8NO3)2, and C60(C5H9NO2)2) at 25°C

    NASA Astrophysics Data System (ADS)

    Semenov, K. N.; Ivanova, N. M.; Charykov, N. A.; Keskinov, V. A.; Kalacheva, S. S.; Duryagina, N. N.; Garamova, P. V.; Kulenova, N. A.; Nabieva, A.

    2017-02-01

    Concentration dependences of the density of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids are studied by pycnometry. Concentration dependences of the average molar volumes and partial volumes of components (H2O and corresponding bisadducts) are calculated for C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems at 25°C. Concentration dependences of the indices of refraction of C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems are determined at 25°C. The concentration dependences of specific refraction and molar refraction of bisadducts and aqueous solutions of them are calculated.

  18. Characterization of human plasma proteome dynamics using deuterium oxide

    PubMed Central

    Wang, Ding; Liem, David A; Lau, Edward; Ng, Dominic CM; Bleakley, Brian J; Cadeiras, Martin; Deng, Mario C; Lam, Maggie PY; Ping, Peipei

    2016-01-01

    Purpose High-throughput quantification of human protein turnover via in vivo administration of deuterium oxide (2H2O) is a powerful new approach to examine potential disease mechanisms. Its immediate clinical translation is contingent upon characterizations of the safety and hemodynamic effects of in vivo administration of 2H2O to human subjects. Experimental design We recruited 10 healthy human subjects with a broad demographic variety to evaluate the safety, feasibility, efficacy, and reproducibility of 2H2O intake for studying protein dynamics. We designed a protocol where each subject orally consumed weight-adjusted doses of 70% 2H2O daily for 14 days to enrich body water and proteins with deuterium. Plasma proteome dynamics was measured using a high-resolution MS method we recently developed. Results This protocol was successfully applied in 10 human subjects to characterize the endogenous turnover rates of 542 human plasma proteins, the largest such human dataset to-date. Throughout the study, we did not detect physiological effects or signs of discomfort from 2H2O consumption. Conclusions and clinical relevance Our investigation supports the utility of a 2H2O intake protocol that is safe, accessible, and effective for clinical investigations of large-scale human protein turnover dynamics. This workflow shows promising clinical translational value for examining plasma protein dynamics in human diseases. PMID:24946186

  19. Spectroscopic and theoretical study of Cu(II), Zn(II), Ni(II), Co(II) and Cd(II) complexes of glyoxilic acid oxime.

    PubMed

    Georgieva, Ivelina; Trendafilova, Natasha; Bauer, Günther

    2006-02-01

    The paper presents a detailed experimental and theoretical study of five metal complexes of glyoxilic acid oxime (gaoH2), Cu(gaoH)2(H2O)2 (1), Zn(gaoH)2(H2O)2 (2), Co(gaoH)2(H2O)2 (3), Ni(gaoH)2(H2O)2 (4) and [Cd(gaoH)2(H2O)2].H2O (5). The electronic and vibrational spectra were measured and discussed as to the most sensitive to the M-L binding bands. Two different types of coordination were considered for gaoH- ligand: bidentate through the carboxylic oxygen and oxime nitrogen in 1-4 and mixed bidentate and bridging through the COO group in 5. It is shown that the spectral behavior of the nu(COO) modes can be used to predict bridging ligand coordination. DFT(B3LYP/6-31++G(d,p)) calculations on model compounds: neutral, anionic and radical forms of gao and Cu(gaoH)2, have been carried out to correlate geometries, electronic and vibrational structures. The results obtained were used to assist the electronic and vibrational analysis of the complexes studied. The effect of the metal-ligand interactions (electrostatic and covalent) on the geometry structure of the ligand was investigated.

  20. A solid-state density functional theory investigation of the effect of metal substitution (Metal = Mn, Cd, Co) on the terahertz spectra of isomorphous molecular metal 5-(4-pyridyl)tetrazolato complexes

    NASA Astrophysics Data System (ADS)

    Pellizzeri, Steven; Witko, Ewelina M.; Korter, Timothy M.; Zubieta, Jon

    2013-09-01

    The crystal structure and experimental terahertz spectroscopy of an isomorphous series [Mn(C6H4N5)2(H2O)4]ṡ2H2O (Mn-4PT), [Co(C6H4N5)2(H2O)4]ṡ2H2O (Co-4PT), and [Cd(C6H4N5)2(H2O)4]ṡ2H2O (Cd-4PT) were compared using solid-state density functional theory (DFT) simulations. The effect of the central metal atom was investigated to determine the influence on the low energy lattice and molecular vibrations exhibited in the region from 10 to 100 cm-1, known as the terahertz (THz) region. Using solid-state DFT the normal modes of these THz vibrations were determined and it was shown that the mass and size of the metal center has a large effect in this region. Each complex exhibited common vibrational modes involving whole ligand motion around the central metal atom. These vibrations were found to shift to lower frequencies with a drastic mass increase; however, this trend is reversed with the smaller mass change between the manganese and cobalt due to the stronger cobalt-nitrogen bond compared to the manganese-nitrogen bond.

  1. Novel bipyridinyl oxadiazole-based metal coordination complexes: High efficient and green synthesis of 3,4-dihydropyrimidin-2(1H)-ones through the Biginelli reactions

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Hua; Zhang, E.; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Ng, Seik Weng

    2016-09-01

    Three new metal coordination complexes, namely, [Co(BPO)2(H2O)4](BS)2(H2O)2 (1), [Co(BPO)2(H2O)4](ABS)2(H2O)2 (2), [Co(BPO)2(H2O)4](MBS)2(H2O)2 (3) [BPO=2,5-di(pyridin-4-yl)-1,3,4-oxadiazole, BS=benzenesulphonate, ABS=4-aminobenzenesulphonate, MBS=4-methylbenzenesulphonate] were obtained under hydrothermal conditions. Complexes 1-3 were structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and thermogravimetric analyses (TGA). All of them display a zero-dimensional motif, in which strong intermolecular hydrogen bonding interactions (O-H···O/N) and packing interactions (C-H···π and π···π) make them achieve a three-dimensional supramolecular architecture. The primary catalytic results of these three complexes show that high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones was observed under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time.

  2. Characterization of titanium dioxide nanoparticles modified with polyacrylic acid and H2O2 for use as a novel radiosensitizer.

    PubMed

    Morita, Kenta; Miyazaki, Serika; Numako, Chiya; Ikeno, Shinya; Sasaki, Ryohei; Nishimura, Yuya; Ogino, Chiaki; Kondo, Akihiko

    2016-12-01

    An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO2/H2O2 NPs) to a tumor exerted a therapeutic enhancement of X-ray irradiation in our previous study. To understand the mechanism of the radiosensitizing effect of PAA-TiO2/H2O2 NPs, analytical observations that included DLS, FE-SEM, FT-IR, XAFS, and Raman spectrometry were performed. In addition, highly reactive oxygen species (hROS) which PAA-TiO2/H2O2 NPs produced with X-ray irradiation were quantified by using a chemiluminescence method and a EPR spin-trapping method. We found that PAA-TiO2/H2O2 NPs have almost the same characteristics as PAA-TiO2. Surprisingly, there were no significant differences in hROS generation. However, the existence of H2O2 was confirmed in PAA-TiO2/H2O2 NPs, because spontaneous hROS production was observed w/o X-ray irradiation. In addition, PAA-TiO2/H2O2 NPs had a curious characteristic whereby they absorbed H2O2 molecules and released them gradually into a liquid phase. Based on these results, the H2O2 was continuously released from PAA-TiO2/H2O2 NPs, and then released H2O2 assumed to be functioned indirectly as a radiosensitizing factor.

  3. Performance of combined sodium persulfate/H2O2 based advanced oxidation process in stabilized landfill leachate treatment.

    PubMed

    Hilles, Ahmed H; Abu Amr, Salem S; Hussein, Rim A; El-Sebaie, Olfat D; Arafa, Anwaar I

    2016-01-15

    A combination of persulfate and hydrogen peroxide (S2O8(2-)/H2O2) was used to oxidizelandfill leachate. The reaction was performed under varying S2O8(2-)/H2O2 ratio (g/g), S2O8(2-)/H2O2 dosages (g/g), pH, and reaction time (minutes), so as to determine the optimum operational conditions. Results indicated that under optimum operational conditions (i.e. 120 min of oxidation using a S2O8(2-)/H2O2 ratio of 1 g/1.47 g at a persulfate and hydrogen peroxide dosage of 5.88 g/50 ml and8.63 g/50 ml respectively, at pH 11) removal of 81% COD and 83% NH3-N was achieved. In addition, the biodegradability (BOD5/COD ratio) of the leachate was improved from 0.09 to 0.17. The results obtained from the combined use of (S2O8(2-)/H2O2) were compared with those obtained with sodium persulfate only, hydrogen peroxide only and sodium persulfate followed by hydrogen peroxide. The combined method (S2O8(2-)/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with the other methods using a single oxidizing agent. Additionally, the study has proved that the combination of S2O8(2-)/H2O2 is more efficient than the sequential use of sodium persulfate followed by hydrogen peroxide in advanced oxidation processes aiming at treatingstabilizedlandfill leachate.

  4. Proton-conductive magnetic metal-organic frameworks, {NR3(CH2COOH)}[M(a)(II)M(b)(III)(ox)3]: effect of carboxyl residue upon proton conduction.

    PubMed

    Ōkawa, Hisashi; Sadakiyo, Masaaki; Yamada, Teppei; Maesato, Mitsuhiko; Ohba, Masaaki; Kitagawa, Hiroshi

    2013-02-13

    Proton-conductive magnetic metal-organic frameworks (MOFs), {NR(3)(CH(2)COOH)}[M(a)(II)M(b)(III)(ox)(3)] (abbreviated as R-M(a)M(b): R = ethyl (Et), n-butyl (Bu); M(a)M(b) = MnCr, FeCr, FeFe) have been studied. The following six MOFs were prepared: Et-MnCr·2H(2)O, Et-FeCr·2H(2)O, Et-FeFe·2H(2)O, Bu-MnCr, Bu-FeCr, and Bu-FeFe. The structure of Bu-MnCr was determined by X-ray crystallography. Crystal data: trigonal, R3c (#161), a = 9.3928(13) Å, c = 51.0080(13) Å, Z = 6. The crystal consists of oxalate-bridged bimetallic layers interleaved by {NBu(3)(CH(2)COOH)}(+) ions. Et-MnCr·2H(2)O and Bu-MnCr (R-MnCr MOFs) show a ferromagnetic ordering with T(C) of 5.5-5.9 K, and Et-FeCr·2H(2)O and Bu-FeCr (R-FeCr MOFs) also show a ferromagnetic ordering with T(C) of 11.0-11.5 K. Et-FeFe·2H(2)O and Bu-FeFe (R-FeFe MOFs) belong to the class II of mixed-valence compounds and show the magnetism characteristic of Néel N-type ferrimagnets. The Et-MOFs (Et-MnCr·2H(2)O, Et-FeCr·2H(2)O and Et-FeFe·2H(2)O) show high proton conduction, whereas the Bu-MOFs (Bu-MnCr, Bu-FeCr, and Bu-FeFe) show moderate proton conduction. Together with water adsorption isotherm studies, the significance of the carboxyl residues as proton carriers is revealed. The R-MnCr MOFs and the R-FeCr MOFs are rare examples of coexistent ferromagnetism and proton conduction, and the R-FeFe MOFs are the first examples of coexistent Néel N-type ferrimagnetism and proton conduction.

  5. The thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. XI. Solubility of synthetic chalcomenite analog and zinc selenite at 25°C

    NASA Astrophysics Data System (ADS)

    Charykova, M. V.; Krivovichev, V. G.; Ivanova, N. M.; Semenova, V. V.

    2015-12-01

    The aim of this study is the synthesis of CuSeO3·2H2O (chalcomenite analog), ZnSeO3·2H2O, and ZnSeO3·H2O and the investigation of their solubility in water. CuSeO3·2H2O has been synthesized from solutions of Cu nitrate and Na selenite, while Zn selenites were synthesized from solutions of Zn nitrate and Na selenite. The samples obtained have been examined with X-ray diffraction and infrared and Raman spectroscopy. The solubility has been determined using the isothermal saturation method in ampoules at 25°C. The solubility has been calculated using the Geochemist's Workbench (GMB 9.0) software package. Solubility products have been calculated for CuSeO3·2H2O (10-10.63), ZnSeO3·2H2O (10-8.35), and ZnSeO3·H2O (10-7.96). The database used comprises thermodynamic characteristics of 46 elements, 47 base particles, 48 redox pairs, 551 particles in solution, and 624 solid phases. The Eh-pH diagrams of the Zn-Se-H2O and Cu-Se-H2O systems were plotted for the average contents of these elements in underground water in oxidation zones of sulfide deposits.

  6. Study on the interaction of a copper(II) complex containing the artificial sweetener aspartame with human serum albumin.

    PubMed

    Shahabadi, Nahid; Khodaei, Mohammad Mehdi; Kashanian, Soheila; Kheirdoosh, Fahimeh; Filli, Soraya Moradi

    2014-05-01

    A copper(II) complex containing aspartame (APM) as ligand, Cu(APM)2Cl2·2H2O, was synthesized and characterized. In vitro binding interaction of this complex with human serum albumin (HSA) was studied at physiological pH. Binding studies of this complex with HSA are useful for understanding the Cu(APM)2Cl2·2H2O-HSA interaction mechanism and providing guidance for the application and design of new and more efficient artificial sweeteners drive. The interaction was investigated by spectrophotometric, spectrofluorometric, competition experiment and circular dichroism. Hyperchromicity observed in UV absorption band of Cu(APM)2Cl2·2H2O. A strong fluorescence quenching reaction of HSA to Cu(APM)2Cl2·2H2O was observed and the binding constant (Kf) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters, enthalpy change (∆H) and entropy change (∆S) were calculated to be -458.67 kJ mol(-1) and -1,339 J mol(-1 )K(-1) respectively. According to the van't Hoff equation, the reaction is predominantly enthalpically driven. In conformity with experimental results, we suggest that Cu(APM)2Cl2·2H2O interacts with HSA. In comparison with previous study, it is found that the Cu(II) complex binds stronger than aspartame.

  7. Metal-induced cyclization of thiosemicarbazones derived from beta-keto amides and beta-keto esters: open-chain and cyclized ligands in zinc(II) complexes.

    PubMed

    Casas, José S; Castaño, María V; Castellano, Eduardo E; Ellena, Javier; García-Tasende, María S; Gato, Angeles; Sánchez, Agustín; Sanjuán, Luisa M; Sordo, José

    2002-03-25

    The reactions of Zn(OAc)(2) with acetoacetanilide, methyl acetoacetate, o-acetoacetanisidide, and ethyl 2-methylacetoacetate thiosemicarbazones (HTSC(1), HTSC(2), HTSC(3), and HTSC(4), respectively) were explored in methanol. With HTSC(1), HTSC(2), and HTSC(3), following isolation of the corresponding zinc(II) thiosemicarbazonates [Zn(TSC(x))(2)] (x = 1, 2, 3), the mother liquors afforded pyrazolonate complexes [ZnL(1)(2)(H(2)O)] (HL(1) = 2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothioamide) that had been formed by cyclization of the corresponding TSC(-). The reaction of HTSC(4) with zinc(II) acetate gave only the pyrazolonate complex [ZnL(2)(2)(H(2)O)] (HL(2) = 2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazole-1-carbothioamide). All compounds were studied by IR and NMR spectroscopy, and HTSC(3), [Zn(TSC(3))(2)] x DMSO, [ZnL(1)(2)(H(2)O)] x 2DMSO, and [ZnL(2)(2)(H(2)O)] x 2DMSO were also studied by X-ray diffractometry, giving a thorough picture of the cyclization process. In preliminary tests of the effects of HL(1) and [ZnL(1)(2)(H(2)O)] on rat paw inflammatory edema induced by carrageenan, HL(1) showed antiinflammatory activity.

  8. Study on the intermolecular interactions of alkylcobaloxime complexes (RCo(dmgH) 2L, dmgH=dimethylglyoxime, R=alkyl, L=H 2O or pyridine)

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Song, Xin-Yi; Li, Yi-Zhi; Chen, Hui-Lan

    2005-07-01

    A series of alkylcobaloxime complexes, [RCo(dmgH) 2L, where dmgH=dimethylglyoxime, R=alkyl, L=neutral monodentate axial ligand], i.e. (EtO 2C) 2C(Me)CH 2Co(dmgH) 2H 2O( 1), n-C 5H 11Co(dmgH) 2H 2O( 2), Br(CH 2) 4Co(dmgH) 2py( 3) and Br(CH 2) 4Co(dmgH) 2H 2O( 4), have been synthesized and characterized. Analysis and comparison of their crystal packing structures with that of our previous reported complexes, COOCH 3(CH 2) 2Co(dmgH) 2H 2O( 5) and c-C 6H 11Co(dmgH) 2H 2O( 6), disclose that one-dimensional ribbon-like zigzag hydrogen bonded networks in 1, 2 and 4 are sustained and controlled by self-assembly between dimethylglyoxime and coordinated water through O-H⋯O - interactions. And the further formation of different types of hydrogen bond linkages with the variation of the axial groups leads to creation of special 2D or 3D architectures. However, the crystal packing structure of 5 and 6 are absolutely different from 1, 2 and 4 due to conformational isomerism effect. Additionally, different types of the protons attachment at O-H⋯O - bridge are observed in 3 and 4, respectively, which is favorable to the intermolecular interactions.

  9. Spectroscopic and theoretical study of Cu(II), Zn(II), Ni(II), Co(II) and Cd(II) complexes of glyoxilic acid oxime

    NASA Astrophysics Data System (ADS)

    Georgieva, Ivelina; Trendafilova, Natasha; Bauer, Günther

    2006-02-01

    The paper presents a detailed experimental and theoretical study of five metal complexes of glyoxilic acid oxime (gaoH 2), Cu(gaoH) 2(H 2O) 2 ( 1), Zn(gaoH) 2(H 2O) 2 ( 2), Co(gaoH) 2(H 2O) 2 ( 3), Ni(gaoH) 2(H 2O) 2 ( 4) and [Cd(gaoH) 2(H 2O) 2]·H 2O ( 5). The electronic and vibrational spectra were measured and discussed as to the most sensitive to the M-L binding bands. Two different types of coordination were considered for gaoH - ligand: bidentate through the carboxylic oxygen and oxime nitrogen in 1- 4 and mixed bidentate and bridging through the COO group in 5. It is shown that the spectral behavior of the ν(COO) modes can be used to predict bridging ligand coordination. DFT(B3LYP/6-31++G(d,p)) calculations on model compounds: neutral, anionic and radical forms of gao and Cu(gaoH) 2, have been carried out to correlate geometries, electronic and vibrational structures. The results obtained were used to assist the electronic and vibrational analysis of the complexes studied. The effect of the metal-ligand interactions (electrostatic and covalent) on the geometry structure of the ligand was investigated.

  10. Removal of citrate and hypophosphite binary components using Fenton, photo-Fenton and electro-Fenton processes.

    PubMed

    Huang, Yao-Hui; Su, Hsiao-Ting; Lin, Li-Way

    2009-01-01

    Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes (Fe2+/H2O2, UV/Fe2+/H2O2, and electrolysis/ Fe2+/H2O2) in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light (photo-Fenton) or electron current (electro-Fenton) was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.

  11. Synthesis, crystal structures, and luminescent properties of Cd(II) coordination polymers assembled from semi-rigid multi-dentate N-containing ligand

    NASA Astrophysics Data System (ADS)

    Yuan, Gang; Shao, Kui-Zhan; Chen, Lei; Liu, Xin-Xin; Su, Zhong-Min; Ma, Jian-Fang

    2012-12-01

    Three new polymers, [Cd(L)2(H2O)2]n (1), [Cd3(L)2(μ3-OH)2(μ2-Cl)2(H2O)2]n (2), {[Cd2(L)2(nic)2(H2O)2]·H2O}n (3) (HL=5-(4-((1H-1,2,4-triazol-1-yl)methyl)phenyl)-1H-tetrazole, Hnic=nicotinic acid) have been prepared and structurally characterized. Compounds 1 and 2 display 2D monomolecular layers built by the inter-linking single helical chains and L- ligands connecting chain-like [Cd(μ3-OH)(μ2-Cl)]n secondary building units, respectively. Compound 3 is constructed from the mixed ligands and possesses a (3,4)-connected framework with (4·82)(4·82·103) topology. Moreover, the fluorescent properties of HL ligand and compounds 1-3 are also been investigated.

  12. Coordinatively Unsaturated Lanthanide(III) Helicates: Luminescence Sensors for Adenosine Monophosphate in Aqueous Media.

    PubMed

    Sahoo, Jashobanta; Arunachalam, Rajendran; Subramanian, Palani S; Suresh, Eringathodi; Valkonen, Arto; Rissanen, Kari; Albrecht, Markus

    2016-08-08

    Coordinatively unsaturated double-stranded helicates [(H2 L)2 Eu2 (NO3 )2 (H2 O)4 ](NO3 )4 , [(H2 L)2 Tb2 (H2 O)6 ](NO3 )6 , and [(H2 L)2 Tb2 (H2 O)6 ]Cl6 (H2 L=butanedioicacid-1,4-bis[2-(2-pyridinylmethylene)hydrazide]) are easily obtained by self-assembly from the ligand and the corresponding lanthanide(III) salts. The complexes are characterized by X-ray crystallography showing the helical arrangement of the ligands. Co-ligands at the metal ions can be easily substituted by appropriate anions. A specific luminescence response of AMP in presence of ADP, ATP, and other anions is observed. Specificity is assigned to the perfect size match of AMP to bridge the two metal centers and to replace quenching co-ligands in the coordination sphere.

  13. [Investigation on composites of europium fluorescent complexes and polyvinylpyrrolidone].

    PubMed

    Hao, Chao-wei; Zhao, Ying; Xu, Yi-zhuang; Wang, Du-jin; Xu, Duan-fu

    2008-09-01

    In order to investigate the relationship between the aggregation structure and fluorescence properties of composites of rare earth fluorescent complexes and polymers, the fluorescent complexes of Eu(TTA)3 x 2H2O and Eu(TTA)3 x (TPPO)2 were synthesized by the reaction of TTA (2-thenoyltrifluoroacetone), TPPO (triphenylphosphine oxide) and EuCl3, and their composites with polyvinylpyrrolidone (PVP K30) were prepared. The fluorescence spectroscopy, FTIR spectroscopy and TEM were used to characterize these composites. Fluorescence spectroscopy results indicated that the fluorescence intensity of the PVP/Eu(TTA)3 x 2H2O composites is obviously improved compared with that of the Eu(TTA)3 x 2H2O complexes. For the composites with the molar ratio of the complexes to the repeat unit of PVP being 1:35, the intensity of 612 nm emission peak of the composites is 5.5 times for PVP/Eu(TTA)3 x 2H2O and 0.3 times for PVP/Eu(TTA)3 x (TPPO)2 higher than that of the corresponding pure rare earth fluorescent complexes. And the emission intensity ratio of 612 to 590 nm peak is 14.7 in PVP/Eu (TTA)3 x 2H2O composite, larger than that of Eu(TTA)3 x 2H2O complexes. These results suggested that the luminescent properties of the europium fluorescent complexes were obviously enhanced in the presence of PVP matrix and there are interactions between the fluorescence complexes and PVP molecules. In the presence of PVPK30, the FTIR spectra of the Eu(TTA)3 x 2H2O complexes were obviously influenced as well. Based on the curve-fitting results of IR spectra of PVP/Eu(TTA)3 2H2O composites with the molar ratio of repeat unit of PVP to Eu(TTA)3 x 2H2O being 7:1 and 2:1, multiple absorption peaks of nu C=O are observed. The IR spectral variations indicated that there are coordination interactions between Eu3+ ions and the carbonyl groups of PVP, and multiple coordination fashion exists. TEM results showed that there are microphase separation structures in PVP/Eu(TTA)3 x 2H2O and PVP/Eu(TTA)3 x (TPPO)2

  14. Deviation between the chemistry of Ce(IV) and Pu(IV) and routes to ordered and disordered heterobimetallic 4f/5f and 5f/5f phosphonates.

    PubMed

    Diwu, Juan; Wang, Shuao; Good, Justin J; DiStefano, Victoria H; Albrecht-Schmitt, Thomas E

    2011-06-06

    The heterobimetallic actinide compound UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O was prepared via the hydrothermal reaction of U(VI) and Ce(IV) in the presence of 1,2-phenylenediphosphonic acid. We demonstrate that this is a kinetic product that is not stable with respect to decomposition to the monometallic compounds. Similar reactions have been explored with U(VI) and Ce(III), resulting in the oxidation of Ce(III) to Ce(IV) and the formation of the Ce(IV) phosphonate, Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O, UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O, and UO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O. In comparison, the reaction of U(VI) with Np(VI) only yields Np[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O and aqueous U(VI), whereas the reaction of U(VI) with Pu(VI) yields the disordered U(VI)/Pu(VI) compound, (U(0.9)Pu(0.1))O(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O, and the Pu(IV) phosphonate, Pu[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. The reactions of Ce(IV) with Np(VI) yield disordered heterobimetallic phosphonates with both M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Np) and M[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Ce, Np) structures, as well as the Ce(IV) phosphonate Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. Ce(IV) reacts with Pu(IV) to yield the Pu(VI) compound, PuO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·3H(2)O, and a disordered heterobimetallic Pu(IV)/Ce(IV) compound with the M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Pu) structure. Mixtures of Np(VI) and Pu(VI) yield disordered heterobimetallic Np(IV)/Pu(IV) phosphonates with both the An[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Np, Pu) and An[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Np, Pu) formulas.

  15. Crystal structure of strychninium chloride dihydrate: Hidden helix in the water/anion tape

    NASA Astrophysics Data System (ADS)

    Białońska, Agata; Ciunik, Zbigniew

    2005-11-01

    The crystal structure of strychninium chloride dihydrate SH +Cl -·2H 2O was determined. The structure is composed of strychnine herring-bone bilayer sheets with channels occupied by the hydrogen bonded anion/water tape between them. Considering different amount of water molecules in isomorphous crystal of SH +Cl -·2H 2O and previously described crystal of strychninium chloride sesquihydrate, we found that water molecules and chloride anions form a left-handed helix. Similarly, anions and water molecules in the crystal of strychnine bromide dihydrate form a left-handed helix related by the two-fold screw axis symmetry. Contrary, in the crystals of strychninium chloride sesquihydrate and SH +Cl -·2H 2O, the helices are related by only translation vector and are stabilized by one or two water bridges, respectively.

  16. Effects of light sources and visible light-activated titanium dioxide photocatalyst on bleaching.

    PubMed

    Suyama, Yuji; Otsuki, Masayuki; Ogisu, Shinichiro; Kishikawa, Ryuzo; Tagami, Junji; Ikeda, Masaomi; Kurata, Hiroshi; Cho, Takahiro

    2009-11-01

    The objective of this study was to evaluate, using methylene blue (MB), the effects of various light sources on the bleaching action of hydrogen peroxide (H(2)O(2)) with two titanium dioxide (TiO(2)) photocatalysts - an ultraviolet light-activated TiO(2) photocatalyst (UVTiO(2)) versus a visible light-activated TiO(2) photocatalyst (VL-TiO(2)). Five experimental solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), H(2)O(2), VL-TiO(2), UV-TiO(2)) were prepared by mixing varying concentrations of H(2)O(2 )and/or TiO(2 )photocatalyst with MB solution. For H(2)O(2)-containing solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), and H(2)O(2)), the concentration of H(2)O(2) was adjusted to 3.5%. For the four different light sources, low- and high-intensity halogen lamps and blue LED LCUs were used. All the experimental solutions were irradiated by each of the light sources for 7 minutes, and the absorbance at 660 nm was measured every 30 seconds to determine the concentration of MB as an indicator of the bleaching effect. On the interaction between the effects of light source and bleaching treatment, the high-intensity halogen with VL-TiO(2)+H(2)O(2) caused the most significant reduction in MB concentration. On the effect of light sources, the halogen lamps resulted in a greater bleaching effect than the blue LED LCUs.

  17. Three two-dimensional coordination polymers constructed from transition metals and 2,3-norbornanedicarboxylic acid: Hydrothermal synthesis, crystal structures and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Wang, Chong-Chen

    2017-02-01

    Three novel coordination polymers based on transition metals like Co(II), Cu(II) and Mn(II), namely [Co2(bpy)2(nbda)2(H2O)2]·2H2O (denoted as BUC-1), [Cu2(bpy)2(nbda)2(H2O)2]·2H2O (BUC-2), [Mn2(bpy)2(nbda)2(H2O)2]·2H2O (BUC-3), (where bpy = 4,4‧-bipyridine, H2nbda = 2,3-norbornanedicarboxylic acid, BUC = Beijing University of Civil Engineering and Architecture), were synthesized under hydrothermal conditions, and characterized by CNH elemental analyses (EA), Fourier Transform infrared spectroscopy (FTIR), and single crystal X-ray diffraction (SCXRD). BUC 1-3 were isostructural and crystallized in the monoclinic space group C2/c, in which the corresponding metal atoms were linked by typical bidentate bpy ligands into two adjacent 1D [M1(bpy)]n2n+ and [M2(bpy)]n2n+ (M = Co(II), Cu(II), Mn(II)), further joined by versatile nbda2- ligands into 2D [M2(bpy)2(nbda)2]n sheets. Finally, three-dimensional supramolecular frameworks were constructed with the aid of the intermolecular hydrogen bonding interactions. BUC 1-3 exhibited different photocatalytic degradation ability to decompose methylene blue (MB) and methyl orange (MO) under UV light irradiation. Additionally, a possible photocatalytic mechanism HOMO-LUMO was proposed and discussed, which was further confirmed by radicals trapping experiments using isopropanol as radical scavenger.

  18. Gallium Arsenate Dihydrate under Pressure: Elastic Properties, Compression Mechanism, and Hydrogen Bonding.

    PubMed

    Spencer, Elinor C; Soghomonian, Victoria; Ross, Nancy L

    2015-08-03

    Gallium arsenate dihydrate is a member of a class of isostructural compounds, with the general formula M(3+)AsO4·2H2O (M(3+) = Fe, Al, In, or Ga), which are being considered as potential solid-state storage media for the sequestration of toxic arsenic cations. We report the first high-pressure structural analysis of a metal arsenate dihydrate, namely, GaAsO4·2H2O. This compound crystallizes in the orthorhombic space group Pbca with Z = 8. Accurate unit cell parameters as a function of pressure were obtained by high-pressure single-crystal X-ray diffraction, and a bulk modulus of 51.1(3) GPa for GaAsO4·2H2O was determined from a third-order Birch-Murnaghan equation of state fit to the P-V data. Assessment of the pressure dependencies of the unit cell lengths showed that the compressibility of the structure along the axial directions increases in the order of [010] < [100] < [001]. This order was found to correlate well with the proposed compression mechanism for GaAsO4·2H2O, which involves deformation of the internal channel void spaces of the polyhedral helices that lie parallel to the [010] direction, and increased distortion of the GaO6 octahedra. The findings of the high-pressure diffraction experiment were further supported by the results from variable-pressure Raman analysis of GaAsO4·2H2O. Moreover, we propose a revised and more complex model for the hydrogen-bonding scheme in GaAsO4·2H2O, and on the basis of this revision, we reassigned the peaks in the OH stretching regions of previously published Raman spectra of this compound.

  19. Synthesis, Characterization, Anticancer, and Antioxidant Studies of Ru(III) Complexes of Monobasic Tridentate Schiff Bases

    PubMed Central

    Ejidike, Ikechukwu P.

    2016-01-01

    Mononuclear Ru(III) complexes of the type [Ru(LL)Cl2(H2O)] (LL = monobasic tridentate Schiff base anion: (1Z)-N′-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)-N-phenylethanimidamide [DAE], 4-[(1E)-N-{2-[(Z)-(4-hydroxy-3-methoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [HME], 4-[(1E)-N-{2-[(Z)-(3,4-dimethoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [MBE], and N-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)benzenecarboximidoyl chloride [DEE]) were synthesized and characterized using the microanalytical, conductivity measurements, electronic spectra, and FTIR spectroscopy. IR spectral studies confirmed that the ligands act as tridentate chelate coordinating the metal ion through the azomethine nitrogen and phenolic oxygen atom. An octahedral geometry has been proposed for all Ru(III)-Schiff base complexes. In vitro anticancer studies of the synthesized complexes against renal cancer cells (TK-10), melanoma cancer cells (UACC-62), and breast cancer cells (MCF-7) was investigated using the Sulforhodamine B assay. [Ru(DAE)Cl2(H2O)] showed the highest activity with IC50 valves of 3.57 ± 1.09, 6.44 ± 0.38, and 9.06 ± 1.18 μM against MCF-7, UACC-62, and TK-10, respectively, order of activity being TK-10 < UACC-62 < MCF-7. The antioxidant activity by DPPH and ABTS inhibition assay was also examined. Scavenging ability of the complexes on DPPH radical can be ranked in the following order: [Ru(DEE)Cl2(H2O)] > [Ru(HME)Cl2(H2O)] > [Ru(DAE)Cl2(H2O)] > [Ru(MBE)Cl2(H2O)]. PMID:27597814

  20. In-source fragmentation technique for the production of thermalized ions.

    PubMed

    Carl, Damon R; Moision, Robert M; Armentrout, P B

    2009-12-01

    Our electrospray ionization-ion funnel-rf hexapole (ESI-IF-6P) source is designed to produce ions for threshold collision-induced dissociation (TCID) studies in a guided ion beam mass spectrometer. This ion source forms an initial distribution of Ca2+(H2O)x ions where x is 6-9. A new in-source fragmentation technique within the hexapole ion guide of the source is described, which is easy to implement and of modest machining and electrical costs, and is able to generate smaller Ca2+(H2O)x complexes, where x = 2-5. Fragmentation is achieved by biasing an assembly of six 0.25 in. long electrodes that are inserted between the hexapole rods. The assembly is positioned in the high-pressure region of the source such that newly formed Ca2+(H2O)x ions undergo enough collisions to become thermalized, as verified by TCID studies. From the initial distribution of ions, fragmentation proceeds along the lowest energy pathway, which corresponds to sequential water loss for most complexes. However, the Ca2+(H2O) complex cannot be formed using this method because charge separation into CaOH+ and H3O+ becomes the lowest energy pathway from the Ca2+(H2O)2 complex. Therefore, this fragmentation technique can be used to identify the critical size complex for M2+(H2O)x systems, which we define as the complex size (x) at which charge separation becomes a lower energy pathway compared with simple ligand loss.

  1. Thermodynamic modeling of ferric phosphate precipitation for phosphorus removal and recovery from wastewater.

    PubMed

    Zhang, Tao; Ding, Lili; Ren, Hongqiang; Guo, Zhitao; Tan, Jing

    2010-04-15

    Phosphorus removal and recovery by ferric phosphate (FePO(4) x 2 H(2)O) precipitation has been considered as an effective technology. In the present study, we examined chemical precipitation thermodynamic modeling of the PHREEQC program for phosphorus removal and recovery from wastewater. The objective of this research was to employ thermodynamic modeling to evaluate the effect of solution factors on FePO(4) x 2 H(2)O precipitation. In order to provide comparison, with the evaluation of thermodynamic modeling, the case study of phosphate removal from anaerobic supernatant was studied. The results indicated that the saturation-index (SI) of FePO(4) x 2 H(2)O followed a polynomial function of pH, and the solution pH influenced the ion activities of ferric iron salts and phosphate. The SI of FePO(4) x 2 H(2)O increased with a logarithmic function of Fe(3+):PO(4)(3-) molar ratio (Fe/P) and initial PO(4)(3-) concentration, respectively. Furthermore, the SI of FePO(4) x 2 H(2)O decreased with a logarithmic function of alkalinity and ionic strength, respectively. With an increase in temperature, the SI at pH 6.0 and 9.0 decreased with a linear function, and the SI at pH 4.0 followed a polynomial function. For the case study of phosphate removal from anaerobic supernatant, the phosphate removal trend at different pH and Fe/P was closer to the predictions of thermodynamic modeling. The results indicated that the thermodynamic modeling of FePO(4) x 2 H(2)O precipitation could be utilized to predict the technology parameters for phosphorus removal and recovery.

  2. Magnesium Chemistry in the Upper Atmosphere

    DTIC Science & Technology

    2010-12-20

    cluster ions with O2, H2O and CO2 , using a flow tube-mass spectrometry technique - studied the reactions of MgO , MgO2, MgO3 and MgCO3 with atomic O using...association reactions of Mg+ cluster ions with O2, H2O and CO2 , using a flow tube- mass spectrometry technique  studied the reactions of MgO , MgO2...fluorescence. In order to establish the technique the reaction MgO + CO → Mg + CO2 H(0 K) = -272 kJ mol-1 (25) was also studied, where CO can

  3. Magnetism, dimensional changes, and magnetic transitions in hydrated cesium manganese chloride

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Aron, P. R.

    1972-01-01

    Dimensional changes (strain) along the three principal crystal axes of the antiferromagnet CsMnCl3-2H2O are studied as a function of magnetic field and temperature in the antiferromagnetic, spin flopped, and paramagnetic phases. Changes in dimensions through the phase transitions between the magnetic states are examined. By applying the molecular field model and utilizing all available information, magnetic properties of CsMnCl3-2H2O are determined. The possible usefulness of this material in a magnetic refrigeration cycle is evaluated.

  4. Structures and spectroscopic properties of Ni(II) and Mn(II) complexes based on 5-(3‧, 5‧-dicarboxylphenyl) picolinic acid ligand

    NASA Astrophysics Data System (ADS)

    Ma, Qi; Song, Jin-Ping; Su, Feng; Guo, Jun-Mei; Guo, Yong; Dong, Chuan

    2016-05-01

    Two novel complexes including [Ni(Hdcppa)(H2O)4] (1) and {[Mn3(dcppa)2(H2O)6]·2H2O}n (2) have been synthesized and characterized by single crystal X-ray structure analysis and elemental analysis. Results show that 1 is a mononuclear nickel(II) compound with octahedron coordination geometry, while 2 is a stairs-like 2D layer structure consisting of the trinuclear MnII units linked through dcppa3-. Spectroscopic and electrochemical properties of the complexes 1-2 have also been studied in dimethyl sulfoxide solution at room temperature.

  5. Solvent extraction of the ion-pairs of chromium(VI) and molybdenum(VI) with trioctylmethylammonium chloride and benzyldimethylcetylammonium chloride.

    PubMed

    Ohashi, K; Shikina, K; Nagatsu, H; Ito, I; Yamamoto, K

    1984-11-01

    The number of capriquat molecules per chromium(VI) atom in the chromate-capriquat ion-association complex has been found to be between one and two. The distribution ratio in the extraction of chromium(VI) with capriquat is dependent on the dielectric constant of the organic solvent, with a minimum at a dielectric constant of about 8. The absorption spectra of the ion-pair extracted into cyclohexane, carbon tetrachloride, benzene and n-butanol are very similar to that of chromate in aqueous solution. The absorption spectra of the chromium(VI)-capriquat extracts in these organic solvents gradually change to an absorption spectrum similar to that of HCrO(4)(-) in aqueous solution. Chromium(VI)-capriquat extracted into chloroform and 1,2-dichloroethane gives absorption spectra similar to that of HCrO(4)(-)in aqueous medium. The chromium(VI)-capriquat species extracted into 1,2-dichloroethane may be (Q(+))(2).CrO(4)(2-)(H(2)O)(n). In contrast, chromium(VI) is extracted with capriquat into the other organic solvents from ammoniacal medium as a mixture of (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).CrO(4)(2-)(H(2)O)(n). The spectral change is ascribed to the change of the extracted species from (Q(+))(2).CrO(4)(2-)(H(2)O)(n) and Q(+)NH(4)(+).CrO(4)(-)(H(2)O)(n) to Q(+).HCrO(4)(2-)(H(2)O)(n-1). The chromium(VI)-zephiramine species extracted is formulated as (Q(+), NH(4)(+))(2)CrO(4)(2-)(H(2)O)(n).(Q(+).Cl(-))(m). Molybdenum(VI) is extracted with capriquat into the same organic solvents as a mixture of (Q(+))(2).MoO(4)(2-)(H(2)O)(n) and Q(+).NH(4)(+).MoO(4)(2-).(H(2)O)(n).

  6. Dipotassium tetra­aqua­bis­[3,5-bis­(dicyano­methyl­ene)cyclo­pentane-1,2,4-trionato(1−)-κN]cobaltate(II)

    PubMed Central

    Chagas, Luciano Honorato; Janczak, Jan; Machado, Flavia C.; de Oliveira, Luiz Fernando C.; Diniz, Renata

    2010-01-01

    The title structure, K2[Co(C11N4O3)2(H2O)4], is isotypic with K2[Fe(C11N4O3)2(H2O)4]. The CoII atom is in a distorted octa­hedral CoN2O4 geometry, forming a dianionic mononuclear entity. Each dianionic unit is associated with two potassium cations and inter­acts with adjacent units through O—H⋯N and O—H⋯O hydrogen bonds. PMID:21589332

  7. Synthesis, spectral characterization, molecular modeling and antimicrobial activity studies on 2-aminopyridine-cyclodiphosph(V)azane derivative and its homo-binuclear zinc(II) complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.

    2014-06-01

    Complexes of zinc(II) of general composition [Zn2(L)X2(H2O)4]nH2O have been synthesized [L = 1,3-dipyridyl-2,4-dioxo-2‧,4‧-bis(2-iminopyridine)cyclodi-phosph(V)azane and X = NO3-; n = 2, OAc-; n = 1, SO42-; n = 2 and Cl-; n = 2]. The elemental analysis, molar conductance measurements, mass, IR, UV, NMR (1H and 31P), TGA, DTA, SEM and XRD spectral studies of the compounds led to the conclusion that the cyclodiphosph(V)azane ligand (H2L) acts as a bidentate manner per zinc ion. The cyclodiphosph(V)azane ligand forms hexa-coordinated complexes having octahedral geometry for Zn(II) complexes. The elemental analyses and mass spectral data have justified the [Zn2(L)X2(H2O)4]nH2O composition of complexes. Infrared spectra of the zinc complexes indicate deprotonation and coordination of the imine NH. It also confirms that nitrogen atoms of the pyridine group contribute to the complexation. The X-ray powder diffraction (XRD) was performed of [Zn2L(SO4)2(H2O)4]2H2O complex. The XRD patterns indicate crystalline nature for the [Zn2L(SO4)2(H2O)4]2H2O complex. The measured low molar conductance values in dimethylformamide indicate that the complexes are non-electrolyte nature. The surface morphology (SEM) of the cyclodiphosph(V)azane ligand and the [Zn2L(NO3)2(H2O)4]2H2O complex were studied by SEM. The thermal studies suggested that the complexes are more stable as compared to ligand. In molecular modeling the geometries of cyclodiphosph(V)azane ligand H2L and its zinc(II) complexes were fully optimized with respect to the energy using the 6-31G basis set. The cyclodiphosph(V)azane ligand and the zinc(II) complexes have been measured in vitro to judge their antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus niger and Pencillium chrysogenum) activities.

  8. Study of the transient "free" OH radical generated in H2O-H2O2 mixtures by stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Li, Fangfang; Ma, Zhiwei; Wang, Shenghan; Li, Tianyu; Sun, Chenglin; Li, Zhanlong; Men, Zhiwei

    2017-03-01

    Forward and backward stimulated Raman scattering (SRS) were studied in the H2O2-H2O mixtures by a strong excitation laser with 532 nm. Only the backward SRS (BSRS) of the H2O2-H2O system shows an unexpected SRS shoulder peak at around 3600 cm- 1, which is similar to the characteristic peak of "free" OH radical. The generation of the "free" OH radical is mainly attributed to the dissociation of hydrogen peroxide (HP) molecules. Simultaneously, the ionization of HP-water clusters generates a part of "free" OH radical under the Laser-induced breakdown (LIB). The interaction of water and HP is also discussed.

  9. Diaqua­bis­(hydrogen tartrato)copper(II) dihydrate

    PubMed Central

    Al-Dajani, Mohammad T.M.; Abdallah, Hassan H.; Mohamed, Nornisah; Hemamalini, Madhukar; Fun, Hoong-Kun

    2010-01-01

    The title complex, [Cu(C4H5O6)2(H2O)2]·2H2O, contains a CuII ion lying on an inversion centre. The coordination geometry of the CuII ion is a distorted octa­hedron with four O atoms from two hydrogen tartrate ions occupying the equatorial positions and two O atoms from two coordinated water mol­ecules occupying the axial positions. In the crystal structure, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. PMID:21587703

  10. Diaqua-bis-(hydrogen tartrato)copper(II) dihydrate.

    PubMed

    Al-Dajani, Mohammad T M; Abdallah, Hassan H; Mohamed, Nornisah; Hemamalini, Madhukar; Fun, Hoong-Kun

    2010-06-16

    The title complex, [Cu(C(4)H(5)O(6))(2)(H(2)O)(2)]·2H(2)O, contains a Cu(II) ion lying on an inversion centre. The coordination geometry of the Cu(II) ion is a distorted octa-hedron with four O atoms from two hydrogen tartrate ions occupying the equatorial positions and two O atoms from two coordinated water mol-ecules occupying the axial positions. In the crystal structure, inter-molecular O-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

  11. Hydrogen-bonded porous coordination polymers: structural transformation, sorption properties, and particle size from kinetic studies.

    PubMed

    Uemura, Kazuhiro; Saito, Kazuya; Kitagawa, Susumu; Kita, Hidetoshi

    2006-12-20

    Three new coordination polymers, [CoCl2(4-pmna)2]n (1), {[Co(NCS)2(4-pmna)2].2Me2CO}n (2 superset 2Me2CO), and {[Co(4-pmna)2(H2O)2](NO3)2.2CH3OH}n (3 superset 2H2O.2MeOH) (4-pmna = N-(pyridin-4-ylmethyl)nicotinamide), have been synthesized and characterized using single-crystal X-ray diffraction. The cobalt(II) atoms are bridged by 4-pmna ligands in all three compounds to form double-stranded one-dimensional "repeated rhomboid-type" chains with rectangular-shaped cavities. In 1, each chain slips and obstructs the neighboring cavities so that there are no guest-incorporated pores. Both 2 superset 2Me2CO and 3 superset 2H2O.2MeOH do not have such a staggered arrangement and have pores that can be filled with a guest molecule. Compound 3 superset 2H2O.2MeOH traps guest molecules with multiple hydrogen bonds and shows a reversible structural rearrangement during adsorption and desorption. The new crystalline compound, 3, is stabilized by forming hydrogen bonds with the amide moieties of the 4-pmna ligands and was characterized using infrared spectroscopy. The clathration enthalpy of the reaction 3 + 2H2O(l) + 2MeOH(l) <==> 3 superset 2H2O.2MeOH (approximately 35 kJ/mol) was estimated from differential scanning calorimetry data by considering the vaporization enthalpies of H2O and MeOH. The desorption process of 3 superset 2H2O.2MeOH --> 3 follows a single zero-order reaction mechanism under isothermal conditions. The activation energy of ca. 100 kJ/mol was obtained by plotting the logarithm of the reaction time for the same reacted fraction versus the reciprocal of the temperature. Moreover, the distribution of the one-dimensional channels in 3 superset 2H2O.2MeOH was estimated using the observation that the reaction rate is directly proportional to the total sectional area.

  12. Preparation, X-ray crystallography, and thermal decomposition of some transition metal perchlorate complexes of hexamethylenetetramine.

    PubMed

    Singh, Gurdip; Baranwal, B P; Kapoor, I P S; Kumar, Dinesh; Fröhlich, Roland

    2007-12-20

    The perchlorate complexes of manganese, nickel, and zinc with hexamethylenetetramine (HMTA) of the general formula [M(H2O-HMTA-H2O)2(H2O-ClO4)2(H2O)2] (where M=Mn, Ni, and Zn) have been prepared and characterized by X-ray crystallography. Thermal studies were undertaken using thermogravimetry (TG), differential thermal analysis (DTA), and explosion delay (DE) measurements. The kinetics of thermal decomposition of these complexes was investigated using isothermal TG data by applying isoconversional method. The decomposition pathways of the complexes have also been proposed. These were found to explode when subjected to higher temperatures.

  13. Preparation and characterization of a degradable magnesium phosphate bone cement.

    PubMed

    Yu, Ying; Xu, Chao; Dai, Honglian

    2016-12-01

    A kind of degradable magnesium phosphate bone cement (MPBC) was fabricated by using the mixed powders of magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4) and calcium dihydrogen phosphate (Ca(H2PO4)2.H2O). As MgKPO4, the main product of MgO and KH2PO4 was alkaline, the Ca(H2PO4)2.H2O was added to neutralize the alkali of the system. And the effects of Ca(H2PO4)2.H2O on the performance of MPBC were discussed. The results showed that the adding of Ca(H2PO4)2.H2O extended the setting time, which was about 6 min to 18 min. The compressive strength increased first and then decreased, and maximum value reached 31.2 MPa after setting for 24 h without any additional pressure. The MPBC was degradable in Tris-HCl solution, and the extracts of the cytotoxicity assay showed that the MPBC had good biocompatibility, indicating that the MPBC had good biodegradable and biocompatible properties.

  14. Synthetic ANaB(NaxLi1 ¡ xMg1)CMg5Si8O22(OH)2 (with x = 0.6, 0.2 and 0) P21/m Amphiboles at High Pressure: a Synchrotron Infrared Study

    SciTech Connect

    Iezzi, G.; Liu, Z; Ventura, D

    2009-01-01

    The high-pressure behavior of three synthetic amphiboles crystallized with space group P21/m at room conditions in the system Li2O-Na2O-MgO-SiO2-H2O has been studied by in situ synchrotron infrared absorption spectroscopy.

  15. Anti-inflammatory drugs. IX. Hydrated diethylammonium (2-(2,6-dichlorophenylamino)phenyl)acetate (HDEA.D.H2O).

    PubMed

    Castellari, C; Comelli, F; Ottani, S

    2001-04-01

    In the solid-state structure of the title compound, C(4)H(12)N(+).C(14)H(10)Cl(2)NO(2)(-).H(2)O, the asymmetric unit contains one cation, one anion and a water molecule. A complex network of hydrogen bonds is present. A comparison is made with the structure of the anhydrous salt.

  16. Structural studies coupling X-ray diffraction and high-energy X-ray scattering in the UO2(2+)-HBr(aq) system.

    PubMed

    Wilson, Richard E; Skanthakumar, S; Cahill, C L; Soderholm, L

    2011-11-07

    The structural chemistry of uranium(VI) in concentrated aqueous hydrobromic acid solutions was investigated using both single crystal X-ray diffraction and synchrotron-based high-energy X-ray scattering (HEXS) to reveal the structure of the uranium(VI) complexes in solution prior to crystallization. The crystal structures of a series of uranyl tetrabromide salts are reported, including Cs(2)UO(2)Br(4), Rb(2)UO(2)Br(4)·2H(2)O, K(2)UO(2)Br(4)·2H(2)O, and (NH(4))(2)UO(2)Br(4)·2H(2)O, as well as a molecular dimer of uranium(VI), (UO(2))(2)(OH)(2)Br(2)(H(2)O)(4). Limited correspondence exists between the structures observed in the solid state and those in solution. Quantitative analysis of the HEXS data show an average U-Br coordination number of 1.9(2) in solution, in contrast to the U-Br coordination number of 4 in the solid salts.

  17. The First Metal Complexes of 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione: Preparation, Physical and Spectroscopic Studies, and Preliminary Antimicrobial Properties

    PubMed Central

    Mostafa, Sahar I.; Papatriantafyllopoulou, Constantina; Perlepes, Spyros P.; Hadjiliadis, Nick

    2008-01-01

    The new complexes [M2O5L2(H2O)2] · H2O (M = Mo, 1; M = W, 2), [RuL2(H2O)2] · H2O (3), [ML3] · xH2O (M = Rh, x = 2, 4; M = Ir, x = 1, 5), [RhL2(PPh3)2](ClO4) · 2H2O (6), [PdL2] · 2H2O (7), [PdL(phen)]Cl · H2O (8), [Re OL2(PPh3)]Cl (9) and [UO2L2] (10) are reported, where LH is 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione. The complexes were characterized by elemental analyses, physical techniques (molar conductivity, room-temperature magnetic susceptibility), and spectroscopic (IR, Raman, UV/VIS/ligand field, NMR, mass) methods. The ligand L− is in its thione form and behaves as a bidentate chelate with the deprotonated (hydroxyl) oxygen and the nitrogen of one amino group as donor atoms. Oxobridged dinuclear (1, 2) and various mononuclear (3–10) structures are assigned for the complexes in the solid state. The metal ion coordination geometries are octahedral (1–6, 9, 10) or square planar (7, 8). The free ligand LH and complexes 1, 4, 7, and 8 were assayed in vitro for antimicrobial activity against two bacterial and two fungal cultures. PMID:19325921

  18. Using Eddy Covariance to Quantify Methane Emissions from a Dynamic Heterogeneous Area

    EPA Science Inventory

    Measuring emissions of CH4, CO2, H2O, and other greenhouse gases from heterogeneous land area sources is challenging. Dynamic changes within the source area as well as changing environmental conditions make individual point measurements less informative than desired, especially w...

  19. Using Eddy Covariance to Quantify Methane Emission from a Dynamic Heterogeneous Area

    EPA Science Inventory

    Measuring emissions of CH4, CO2, H2O, and other greenhouse gases from heterogeneous land area sources is challenging. Dynamic changes within the source area as well as changing environmental conditions make individual point measurements less informative than desired, especially w...

  20. Synthesis, spectral characterization and microbiological studies of Co(II), Ni(II) and Cu(II) complexes with some novel 20-membered macrocyclic hydrazino-1,2,4-triazole Schiff bases.

    PubMed

    Avaji, Prakash Gouda; Patil, Sangamesh Amarappa

    2009-02-01

    A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized by template condensation of 2,6-diformyl-4-methylphenol and 3-substituted-4-amino-5-hydrazino-1,2,4-triazole with CoCl(2).6H(2)O, NiCl(2).6H(2)O and CuCl(2).2H(2)O chlorides in 2 + 2+2 molar ratio in ethanol. These complexes were characterized by elemental analyses, magnetic susceptibility, molar conductance, spectral (IR, Uv-Vis, ESR, (1)H NMR and FAB-mass), thermal, fluorescence and solid-state DC electrical conductivity studies. The observed molar conductance values indicate that they are non-electrolytes. Elemental analyses suggest the complexes to have 2:1 stoichiometry of the type [M(2)LX(2)] 2H(2)O (M = Co(II) & Cu(II), L = L(I)-L(IV) and X = Cl) and [Ni(2)LX(2)2H(2)O] 2H(2)O. The solid state DC electrical conductivity showed that the complexes were semiconducting. All the Schiff bases and their Co(II), Ni(II) and Cu(II) complexes were evaluated for their microbiological properties and some compounds showed promising results.

  1. Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes.

    PubMed

    Baran, Talat; Menteş, Ayfer; Arslan, Hülya

    2015-01-01

    In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and (13)C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a] · 2H2O and [O-CMCS-4a] · 2H2O). Thus, the solubility problem of chitosan in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2] · 2H2O and [O-CMCS-4a-Cu(OAc)2] · 2H2O, was conducted using FTIR, UV-Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements.

  2. The thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores: VIII. Field of thermal stability of synthetic analog of chalcomenite, its dehydration and dissociation

    NASA Astrophysics Data System (ADS)

    Fokina, E. L.; Klimova, E. V.; Charykova, M. V.; Krivovichev, V. G.; Platonova, N. V.; Semenova, V. V.; Depmeier, W.

    2014-12-01

    The objective of this paper is to study the thermal stability of the synthetic analog of chalcomenite, CuSeO3 · 2H2O, and its dehydration and dissociation, in an experimental context. The study has been carried out by a comprehensive application of thermogravimetry (TG), differential scanning calorimetry (DSC), and high-temperature X-ray diffraction at a temperature range of 25-600°C. It has been established that CuSeO3 · 2H2O dehydrates at 202-264°C in three stages corresponding to the formation of intermediate CuSeO3 · 2H2O and CuSeO3 · 1/3H2O hydrate phases. At 480-595°C anhydrous CuSeO3 breaks down into CuO and SeO2 via the formation of a Cu4O(SeO3)3 phase. Enthalpies of the reactions at each stage of the CuSeO3 · 2H2O dehydration and CuSeO3 dissociation have been determined and their kinetic analysis has been carried out.

  3. A series of phenyl sulfonate metal coordination polymers as catalysts for one-pot Biginelli reactions under solvent-free conditions.

    PubMed

    Wang, Jin-Hua; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Wang, Jun-Jie; Ng, Seik Weng

    2015-10-28

    Three new metal coordination polymers, namely, [Co(DPP)2(H2O)2]·(BS)2·2H2O (1), [Co(DPP)2(H2O)2]·(ABS)2·2H2O (2) and [Co(DPP)2(MBS)2] (3) [DPP = 1,3-di(pyridin-4-yl)propane, BS = phenyl sulfonic acid, ABS = p-aminobenzene sulfonic acid, MBS = p-methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1-3 were structurally characterized using X-ray single-crystal diffraction, XRD and IR spectroscopy. Both complexes 1 and 2 display a 1D tape structure. Meanwhile, complex 3 exhibits a 2D layer and further stacks via C-Hπ interactions to generate a three-dimensional supramolecular architecture. These three metal coordination polymers have been applied as catalysts for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions through the Biginelli reaction. Interestingly, the catalysis products have been obtained in high yields under eco-friendly synthesis conditions.

  4. Transition metal(II) complexes of vitamin B13 with monodentate orotate(1-) ligands

    NASA Astrophysics Data System (ADS)

    Köse, Dursun Ali; Zümreoglu-Karan, Birgül; Şahin, Onur; Büyükgüngör, Orhan

    2006-05-01

    The formation of bisorotate(1-) complexes of the type [M(C 5H 3N 2O 4) 2(H 2O) 4]· nH 2O (M=Co, Ni, Zn and n=2, 4) was achieved by the reaction of ammonium orotate with the corresponding M(II) ions. The crystal structure of [Co(C 5H 3N 2O 4) 2(H 2O) 4]·2H 2O was determined by single crystal X-ray diffraction analysis. Each Co(II) ion in the monomeric Co(C 5H 3N 2O 4) 2(H 2O) 4 units adapts a slightly distorted octahedral geometry comprised of two monodentate orotate anions and four H 2O ligands. Columnar packing of pyrimidine rings along the c axis leads to the formation of layers that propagate parallel to the b axis and the adjacent layers are linked by hydrogen bonds forming a 3D lattice. Complexes of nickel and zinc were assumed to contain monodentate bound orotate ligands as well on the basis of physical and spectroscopic data.

  5. Interaction of a copper (II) complex containing an artificial sweetener (aspartame) with calf thymus DNA.

    PubMed

    Shahabadi, Nahid; Khodaei, Mohammad Mehdi; Kashanian, Soheila; Kheirdoosh, Fahimeh

    2014-01-01

    A copper (II) complex containing aspartame (APM) as ligand, Cu(APM)2Cl2⋅2H2O, was synthesized and characterized. In vitro binding interaction of this complex with native calf thymus DNA (CT-DNA) was studied at physiological pH. The interaction was studied using different methods: spectrophotometric, spectrofluorometric, competition experiment, circular dichroism (CD) and viscosimetric techniques. Hyperchromicity was observed in UV absorption band of Cu(APM)2Cl2⋅2H2O. A strong fluorescence quenching reaction of DNA to Cu(APM)2Cl2⋅2H2O was observed and the binding constants (Kf) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated to be+89.3 kJ mol(-1) and+379.3 J mol(-1) K(-1) according to Van't Hoff equation which indicated that reaction is predominantly entropically driven. Experimental results from spectroscopic methods were comparable and further supported by viscosity measurements. We suggest that Cu(APM)2Cl2⋅2H2O interacts with calf thymus DNA via a groove interaction mode with an intrinsic binding constant of 8×10+4 M(-1). Binding of this copper complex to DNA was found to be stronger compared to aspartame which was studied recently.

  6. 21 CFR 184.1452 - Manganese gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...; milk products as defined in § 170.3(n)(31) of this chapter; and poultry products as defined in § 170.3(n)(34) of this chapter. The ingredient may be used in infant formulas in accordance with section 412...·2H2O, CAS Reg. No. 648-0953-0998) is a slightly pink colored powder. It is obtained by...

  7. 21 CFR 184.1792 - Sodium sesquicarbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium sesquicarbonate. 184.1792 Section 184.1792... GRAS § 184.1792 Sodium sesquicarbonate. (a) Sodium sesquicarbonate (Na2CO3·NaHCO3·2H2O, CAS Reg. No..., centrifugation, and drying; (2) double refining of trona ore, a naturally occurring impure sodium...

  8. Comparative EXAFS investigation of uranium(VI) and -(IV) aquo chloro complexes in solution using a newly developed spectroelectrochemical cell.

    PubMed

    Hennig, C; Tutschku, J; Rossberg, A; Bernhard, G; Scheinost, A C

    2005-09-19

    The coordination of the U(IV) and U(VI) ions as a function of the chloride concentration in aqueous solution has been studied by U L(III)-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The oxidation state of uranium was changed in situ using a gastight spectroelectrochemical cell, specifically designed for the safe use with radioactive solutions. For U(VI) we observed the complexes UO2(H2O)5(2+), UO2(H2O)4Cl+, UO2(H2O)3Cl2(0), and UO2(H2O)2Cl3- with [Cl-] increasing from 0 to 9 M, and for U(IV) we observed the complexes U(H2O)9(4+), U(H2O)8Cl3+, U(H2O)(6-7)Cl2(2+), and U(H2O)5Cl3+. The distances in the U(VI) coordination sphere are U-Oax = 1.76+/-0.02 A, Oeq = 2.41 +/- 0.02 A, and U-Cl = 2.71 +/- 0.02 A; the distances in the U(IV) coordination sphere are U-O = 2.41 +/- 0.02 A and U-Cl = 2.71 +/- 0.02 A.

  9. Relaxivity enhancement of aquated Tris(β-diketonate)gadolinium(III) chelates by confinement within ultrashort single-walled carbon nanotubes.

    PubMed

    Law, Justin J; Guven, Adem; Wilson, Lon J

    2014-01-01

    Ultrashort single-walled carbon nanotubes loaded with gadolinium ions (gadonanotubes) have been previously shown to exhibit extremely high T1 -weighted relaxivities (>100 mm(-1) s(-1) ). To further examine the effect of nanoconfinement on the relaxivity of gadolinium-based contrast agents for magnetic resonance imaging, a series of ultrashort single-walled carbon nanotube (US-tube) materials internally loaded with gadolinium chelates have been prepared and studied. US-tubes were loaded with Gd(acac)3  · 2H2 O, Gd(hfac)3  · 2H2 O, and Gd(thd)3 (acac = acetylacetone, hfac = hexafluoroacetylacetone, thd = tetramethylheptanedione). The longitudinal relaxivities of the prepared materials determined at 25°C in a 1.5 T field were 103 mm(-1) s(-1) for Gd(acac)3  · 2H2 O@US-tubes, 105 mm(-1) s(-1) for Gd(hfac)3  · 2H2 O@US-tubes and 26 mm(-1) s(-1) for Gd(thd)3 @US-tubes. Compared with the relaxivities obtained for the unloaded chelates (<10 mm(-1) s(-1) ) as well as accounting for the T1 reduction observed for the empty US-tubes, the boost in relaxivity for chelate-loaded US-tubes is attributed to confinement within the nanotube and depends on the number of coordinated water molecules.

  10. Crystal structure of poly[[hexa­qua-1κ4 O,2κ2 O-bis­(μ3-pyridine-2,4-di­car­box­ylato-1κO 2:2κ2 N,O 2′;1′κO 4)cobalt(II)­strontium(II)] dihydrate

    PubMed Central

    Yu, Zhaojun; Jiang, Peng; Chen, Yanmei

    2015-01-01

    In the title polymeric complex, {[CoSr(C7H3NO4)2(H2O)6]·2H2O}n, the CoII ion, which is situated on a crystallographic centre of inversion, is six-coordinated by two O atoms and two N atoms from two pyridine-2,4-di­carboxyl­ate (pydc2−) ligands and two terminal water mol­ecules in a slightly distorted octa­hedral geometry, to form a trans-[Co(pydc)2(H2O)2]2− unit. The SrII ion, situated on a C 2 axis, is coordinated by four O atoms from four pydc2− ligands and four water mol­ecules. The coordination geometry of the SrII atom can be best described as a distorted dodeca­hedron. Each SrII ion bridges four [Co(pydc)2(H2O)2]2− units by four COO− groups of four pydc2− ligands to form a three-dimensional network structure. Two additional solvent water mol­ecules are observed in the crystal structure and are connected to the three-dimensional coordination polymer by O—H⋯O hydrogen bonds. Further intra- and intermolecular O—H⋯O hydrogen bonds consolidate the overall structure. PMID:26396869

  11. Preparation and characterization of a degradable magnesium phosphate bone cement

    PubMed Central

    Yu, Ying; Xu, Chao; Dai, Honglian

    2016-01-01

    A kind of degradable magnesium phosphate bone cement (MPBC) was fabricated by using the mixed powders of magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4) and calcium dihydrogen phosphate (Ca(H2PO4)2.H2O). As MgKPO4, the main product of MgO and KH2PO4 was alkaline, the Ca(H2PO4)2.H2O was added to neutralize the alkali of the system. And the effects of Ca(H2PO4)2.H2O on the performance of MPBC were discussed. The results showed that the adding of Ca(H2PO4)2.H2O extended the setting time, which was about 6 min to 18 min. The compressive strength increased first and then decreased, and maximum value reached 31.2 MPa after setting for 24 h without any additional pressure. The MPBC was degradable in Tris–HCl solution, and the extracts of the cytotoxicity assay showed that the MPBC had good biocompatibility, indicating that the MPBC had good biodegradable and biocompatible properties. PMID:27482465

  12. Supramolecular compounds constructed by main group metals, polyoxotungstates and polyaminepolycarboxylate

    NASA Astrophysics Data System (ADS)

    Zhang, Chun-Hua; Chen, Ya-Guang; Liu, Shu-Xia

    2013-06-01

    Five supramolecular compounds of main group metals, polyoxotungstates (BW5- and SiW4-) and trans-1,2-diaminocyclohexanetetraacetic acid (H4DCTA), (NH4)4 [Ca2Na2(H2O)12(HDCTA)2(HBW12O40)]·6H2O (1), (NH4)4[Sr2Na2(H2O)14(HDCTA)2(HBW12O40)]·7H2O (2), (NH4)6[Al(DCTA)]2[SiW12O40]·12H2O (3), (NH4)6[Pb3(H2O)2(DCTA)2][SiW12O40]·8H2O (4), [Na6Bi2(H2O)22(DCTA)2] [SiW12O40]·2H2O(5), were synthesized in aqueous solution and were characterized by IR spectroscopy, thermogravitic analysis, powder and single-crystal X-ray diffraction techniques. Single-crystal structure analyses indicate that in 1 and 2, HDCTA and BW5- coordinate simultaneously to M ions, forming HDCTA-M-BW12 chains; in 3 and 4 Al-DCTA complex and trinuclear Pb-DCTA complex are formed; in 5, HDCTA/DCTA combines Bi3+ and Na+, forming coordination polymer chains. A lot of hydrogen bonds between the building units fuse the building units into 3D supramolecular architectures. Thermal decomposition processes of these compounds changes with the structures of component units and metal ions.

  13. Wind and Wind Stress Measurements in HiRes

    DTIC Science & Technology

    2008-09-30

    Met One Cups (wind speed), Campbell Scientific CSAT3 (3D sonic anemometer ), LI-COR LI-7500 (CO2/H2O Analyzer), and ParoScientific Met4a (pressure...Met One Cup CSAT 3 LI-COR ParoScientific Figure 2: Prototype Mast with Sensor Array 4 IMPACT

  14. Dihydroxyacetone (DHA) monomer complexes with CaBr2 and CdCl2.

    PubMed

    Rlepokura, Katarzyna; Lis, Tadeusz

    2008-03-01

    Two hydrated complexes of monomeric dihydroxyacetone (DHA; the simplest ketose), viz. the calcium bromide complex bis(mu-dihydroxyacetone)bis[tetraaquacalcium(II)] tetrabromide (isomorphous with the chloride compound reported previously), [Ca(2)(C(3)H(6)O(3))(2)(H(2)O)(8)]Br(4), (2e), and the cadmium chloride complex poly[[bis(mu-dihydroxyacetone)bis[bis(dihydroxyacetone)cadmium(II)

  15. Supramolecular architectures constructed by lanthanum, amino acids and 1,10-phenanthroline via non-covalent bond interactions

    NASA Astrophysics Data System (ADS)

    Zheng, Xiang-Jun; Jin, Lin-Pei

    2003-07-01

    Three supramolecular lanthanum coordination compounds of amino acids, with 1,10-phenanthroline (phen), [La 2(APA) 6(phen) 2(H 2O) 2](ClO 4) 6(phen) 4·2H 2O ( 1), [La 2(ABA) 6(phen) 2(H 2O) 2](ClO 4) 6 (phen) 6·4H 2O ( 2), and [La 2(AHA) 4(phen) 4](ClO 4) 6(phen) 4·2H 2O ( 3) (APA=3-aminopropionic acid; ABA=4-aminobutanoic acid; AHA=6-aminohexanoic acid) were synthesized and characterized by single crystal X-ray diffraction. The results show that the three coordination compounds are all composed of binuclear coordination cations built by metal-ligand coordination. Through hydrogen bonding and π-π stacking interactions, complex 1 forms a two-dimensional supramolecular sheet structure extending in the (001) plane, complex 2 forms a three-dimensional supramolecular network with many cavities occupied by ClO 4- and lattice H 2O molecules, and complex 3 forms a two-dimensional supramolecular lamellar structure in the (100) plane.

  16. Cobalt selenite dihydrate as an effective and stable Pt-free counter electrode in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Dong, Jia; Wu, Jihuai; Jia, Jinbiao; Fan, Leqing; Lan, Zhang; Lin, Jianming; Wei, Yuelin

    2016-12-01

    Cobalt selenite dihydrate (CoSeO3·2H2O) is spin-coated on conductive glass and used as counter electrode (CE) in dye-sensitized solar cells (DSSCs). Owing to CoSeO3·2H2O electrode good electrocatalytic activity, high conductivity and low resistance, the DSSC based on optimal CoSeO3·2H2O CE provides a power conversion efficiency of 8.90% under one sun irradiation from the front of DSSC, which is superior to the DSSC based on conventional Pt CE. Furthermore, when incorporating trace amounts of reduced graphene oxide (rGO) into CoSeO3·2H2O CE, the DSSC device achieves an improved power conversion efficiency of 9.89%. The research presented here indicates that hydration oxysalt can be used as efficient, stable and free-Pt counter electrode material and shows excellent prospects for application in DSSCs.

  17. Vitamin A equivalence of spirulina beta-carotene in Chinese adults assessed by stable isotope dilution and reference techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Spirulina is a high-protein food supplement that contains carotenoids. Objective: The study aimed at determining the vitamin A equivalence of spirulina beta-carotene in humans. Design: Spirulina was grown in a 23 atom% 2H2O cultural solution. Spirulina beta-carotene showed the highest ab...

  18. Vitamin A Value of Spirulina B-carotene in Chinese Adults Assessed by Stable Isotope Dilution Technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To determine the vitamin A value of spirulina B-carotene (B-C) in humans, spirulina was intrinsically labeled by growing the plant in 25 atom% 2H2O nutrient solution. Isotopomers of spirulina trans-B-C showed the highest aboundant enrichment at molecular mass plus 10 mass units (2H10 trans-B-C). Ten...

  19. Propagation of sound through the Earth's atmosphere. 1: Measurement of sound absorption in the air. 2: Measurement of ground impedance

    NASA Technical Reports Server (NTRS)

    Becher, J.; Meredith, R. W.; Zuckerwar, A. J.

    1981-01-01

    The fabrication of parts for the acoustic ground impedance meter was completed, and the instrument tested. Acoustic ground impedance meter, automatic data processing system, cooling system for the resonant tube, and final results of sound absorption in N2-H2O gas mixtures at elevated temperatures are described.

  20. Synthesis, crystal structures, molecular docking, in vitro monoamine oxidase-B inhibitory activity of transition metal complexes with 2-{4-[bis (4-fluorophenyl)methyl]piperazin-1-yl} acetic acid

    NASA Astrophysics Data System (ADS)

    Yang, Dan-dan; Wang, Riu; Zhu, Jin-long; Cao, Qi-yue; Qin, Jie; Zhu, Hai-liang; Qian, Shao-song

    2017-01-01

    Three novel complexes, [Cu(L)2(H2O)](1), [Zn(L)2(H2O)2]·CH3OH·1.5H2O(2), and [Ni(L)2(H2O)1.8]·CH3OH·1.2H2O (3) (HL = 2-{4-[bis(4-fluorophenyl)methyl]pipera-zin-1-yl} acetic acid), were synthesized and structurally determined by single-crystal X-ray diffraction. Molecular docking study preliminarily revealed that complex 1 had potential Monoamine oxidase B inhibitory activity. All acquired compounds were tested against rat brain MAO-B in vitro. In accordance with the result of calculation, it showed complex 1 (IC50 = 1.85 ± 0.31 μM) have good inhibitory activity against MAO-B at the same micromolar concentrations with positive control Iproniazid Phosphate (IP, IC50 = 7.59 ± 1.17 μM). These results indicated that complex 1 was a potent MAO-B inhibitor.

  1. Yellow maize with high beta-carotene is an effective source of vitamin A in healthy Zimbabwean men

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bioconversion efficiency of yellow maize beta-carotene to retinol in humans is unknown. Thus, the objective of this study was to determine the vitamin A value of yellow maize beta-carotene in humans. A high beta-carotene containing yellow maize was grown in a hydroponic medium with 23 atom% 2H2O...

  2. Binary and ternary new water soluble copper(II) complexes of L-tyrosine and substituted 1,10-phenanthrolines: Effect of substitution on DNA interactions and cytotoxicities

    NASA Astrophysics Data System (ADS)

    İnci, Duygu; Aydın, Rahmiye; Vatan, Özgür; Yılmaz, Dilek; Gençkal, Hasene Mutlu; Zorlu, Yunus; Cavaş, Tolga

    2015-06-01

    Binary and ternary water soluble copper(II) complexes - [Cu(nphen)2(H2O)](NO3)2·H2O (1), [Cu(phen)2(H2O)](NO3)2 (2), [Cu(nphen)(L-tyr)(H2O)]NO3·2H2O (3), [Cu(phen)(tyr)(H2O)] NO3·2H2O (4) - and diquarternary salts of nphen and phen (nphen = 5-nitro-1,10-phenanthroline, phen = 1,10-phenanthroline and tyr = L-tyrosine) have been synthesized and characterized by CHN analysis, 1H NMR, 13C NMR and IR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. The CT-DNA binding properties of these compounds have been investigated by thermal denaturation measurements, absorption and emission spectroscopy. The supercoiled pUC19 plasmid DNA cleavage activity of these compounds has been explored by agarose gel electrophoresis. The cytotoxicity of these compounds against MCF-7, Caco-2, A549 cancer cells and BEAS-2B healthy cells was also studied by using XTT method. The complexes 1-4 exhibit significant high cytotoxicity with low IC50 values in compared with cisplatin. The effect of the substituents of phen and coordinated amino acid in the above complexes are presented and discussed.

  3. Application of gypsum to control P runoff from poultry litter fertilization of pasture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper will discuss the utilization of gypsum (CaSO4 .2H2O) to reduce P losses from surface runoff when poultry litter is used as a fertilizer source in agriculture. Utilization of poultry litter as a fertilizer source is common in regions with intense poultry production. While poultry litter ...

  4. Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

    PubMed Central

    Takebayashi, Satoshi; Shizuno, Tsubasa; Otani, Takashi

    2012-01-01

    Summary [RhCp*(OAc)2(H2O)] [Cp* = pentamethylcyclopentadienyl] catalyzed the C–H bond amidation of ferrocenes possessing directing groups with isocyanates in the presence of 2 equiv/Rh of HBF4·OEt2. A variety of disubstituted ferrocenes were prepared in high yields, or excellent diastereoselectivities. PMID:23209521

  5. Sonochemical synthesis and characterization of three nano zinc(II) coordination polymers; Precursors for preparation of zinc(II) oxide nanoparticles.

    PubMed

    Marandi, Farzin; Hashemi, Lida; Morsali, Ali; Krautscheid, Harald

    2016-09-01

    Nanostructures of three Zinc(II) coordination polymers, [Zn(NNO)2(H2O)4]n (1), [Zn(PNNO)2(H2O)2]n (2) and [Zn(H2O)6]·(INNO)2 (3) {NNO: Nicotinic acid N-oxide, PNNO: Picolinic acid N-oxide and INNO: Isonicotinic acid N-oxide}, have been synthesized by a sonochemical process and reaction of ligands with Zn(CH3COO)2. The Zinc(II) oxide nano-particles have been synthesized from thermolysis of [Zn(NNO)2(H2O)4]n (1), [Zn(PNNO)2(H2O)2]n (2) and [Zn(H2O)6]·(INNO)2 (3) at two different methods (with surfactant and without surfactant) and two temperatures (200 and 600°C). The ZnO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Comparison of the SEM images of ZnO nano-particles at two different methods and temperatures shows that higher temperature results in an increasing of agglomeration and thus small and spherical ZnO particles with good separation were produced by thermolysis of compounds at 200°C and by use of surfactant.

  6. An Easy Way To Make Chlorine Water

    NASA Astrophysics Data System (ADS)

    Holmes, L. H., Jr.

    1997-11-01

    Chlorine water can be made easily by mixing hypochlorite and hydrochloric acid. The equilibrium lies toward Cl2 in the reaction HOCl + HCl -> Cl2 + H2O and this can be used to make chlorine water from sodium hypochlorite and hydrochloric acid if the presence of NaCl in the chlorine water does not interfere with its use.

  7. Serpentine by Hydrogenation of Fe-rich Ferromagnesiosilica PCs in Aggregate IDPs

    NASA Technical Reports Server (NTRS)

    Rietmeijer, F. J. M.; Nuth, J. A., III

    2001-01-01

    Condensed hydrogen-bearing magnesiosilica smokes support that hydrogenation at H2/H2O ratios may lead to the formation of rare Fe-rich serpentine plus metallic iron in ferromagnesiosilica PCs with appropriate (Mg,Fe)/Si ratios that were acquired during their formation. Additional information is contained in the original extended abstract.

  8. Stoichiometry of the heparin-Cu2+-glycine mixed-ligand complex according to differential thermal analysis and IR spectroscopy data

    NASA Astrophysics Data System (ADS)

    Feofanova, M. A.; Frantseva, Yu. V.; Zhuravlev, E. V.; Baranova, N. V.; Ryasenskii, S. S.

    2015-02-01

    A method or the synthesis, isolation, and purification of a mixed-ligand complex of heparin with copper and glycine cations was suggested. The complex was studied by elemental, thermal, and spectral analyses. The elemental and crystalline hydrate compositions of the complex were determined and the molecular formula was suggested to be Na3CuHepGly · 2H2O.

  9. Flue gas desulfurization gypsum agricultural network alabama (cotton)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flue gas desulfurization gypsum (FGDG) is an excellent source of gypsum (CaSO4•2H2O) that can be beneficially used in agriculture. Research was conducted as part of the Flue Gas Desulfurization Gypsum Agricultural Network program sponsored by the Electric Power Research Institute in collaboration wi...

  10. Utilization of FGD gypsum in agriculture for environmental benefits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper will discuss the utilization of FGD gypsum in agriculture for environmental benefits. Gypsum (CaSO4 .2H2O) has been used as an agricultural soil amendment for over 250 years. It is a soluble source of calcium and sulfur for crops and has been shown to improve soil physical and chemical pr...

  11. Impact of FGD gypsum soil amendment applications on soil and environmental quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper will discuss the utilization of FGD gypsum in agriculture for improving soil quality and other environmental benefits. Gypsum (CaSO4 .2H2O) has been used as an agricultural soil amendment for over 250 years. It is a soluble source of calcium and sulfur- for crops and has been shown to i...

  12. A proposed NRCS conservation practice standard: Amending soil properties with gypsiferous products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper will discuss the proposed new NRCS conservation practice standard regarding the use of gypsiferous products in agriculture. Gypsiferous products include gypsum (CaSO4 .2H2O), has been used as an agricultural soil amendment for over 250 years as a soluble source of calcium and sulfur for ...

  13. Time-Resolved Infrared Reflectance Studies of the Dehydration-Induced Transformation of Uranyl Nitrate Hexahydrate to the Trihydrate Form

    SciTech Connect

    Johnson, Timothy J.; Sweet, Lucas E.; Meier, David E.; Mausolf, Edward J.; Kim, Eunja; Weck, Philippe F.; Buck, Edgar C.; McNamara, Bruce K.

    2015-10-01

    Uranyl nitrate is a key species in the nuclear fuel cycle. However, this species is known to exist in different states of hydration, including the hexahydrate ([UO2(NO3)2(H2O)6] often called UNH), the trihydrate [UO2(NO3)2(H2O)3 or UNT], and in very dry environments the dihydrate form [UO2(NO3)2(H2O)2]. Their relative stabilities depend on both water vapor pressure and temperature. In the 1950s and 1960s the different phases were studied by infrared transmission spectroscopy, but were limited both by instrumental resolution and by the ability to prepare the samples for transmission. We have revisited this problem using time-resolved reflectance spectroscopy, which requires no sample preparation and allows dynamic analysis while the sample is exposed to a flow of N2 gas. Samples of known hydration state were prepared and confirmed via X-ray diffraction patterns of known species. In reflectance mode the hexahydrate UO2(NO3)2(H2O)6 has a distinct uranyl asymmetric stretch band at 949.0 cm-1 that shifts to shorter wavelengths and broadens as the sample desiccates and recrystallizes to the trihydrate, first as a shoulder growing in on the blue edge but ultimately results in a doublet band with reflectance peaks at 966 and 957 cm-1. The data are consistent with transformation from UNH to UNT as UNT has two inequivalent UO22+ sites. The dehydration of UO2(NO3)2(H2O)6 to UO2(NO3)2(H2O)3 is both a structural and morphological change that has the lustrous lime green UO2(NO3)2(H2O)6 crystals changing to the matte greenish yellow of the trihydrate solid. The phase transformation and crystal structures were confirmed by density functional theory calculations and optical microscopy methods, both of which showed a transformation with two distinct sites for the uranyl cation in the trihydrate, with but one in the hexahydrate.

  14. Infrared optical constants of crystalline sodium chloride dihydrate: application to study the crystallization of aqueous sodium chloride solution droplets at low temperatures.

    PubMed

    Wagner, Robert; Möhler, Ottmar; Schnaiter, Martin

    2012-08-23

    Complex refractive indices of sodium chloride dihydrate, NaCl·2H(2)O, have been retrieved in the 6000-800 cm(-1) wavenumber regime from the infrared extinction spectra of crystallized aqueous NaCl solution droplets. The data set is valid in the temperature range from 235 to 216 K and was inferred from crystallization experiments with airborne particles performed in the large coolable aerosol and cloud chamber AIDA at the Karlsruhe Institute of Technology. The retrieval concept was based on the Kramers-Kronig relationship for a complex function of the optical constants n and k whose imaginary part is proportional to the optical depth of a small particle absorption spectrum in the Rayleigh approximation. The appropriate proportionality factor was inferred from a fitting algorithm applied to the extinction spectra of about 1 μm sized particles, which, apart from absorption, also featured a pronounced scattering contribution. NaCl·2H(2)O is the thermodynamically stable crystalline solid in the sodium chloride-water system below the peritectic at 273.3 K; above 273.3 K, the anhydrous NaCl is more stable. In contrast to anhydrous NaCl crystals, the dihydrate particles reveal prominent absorption signatures at mid-infrared wavelengths due to the hydration water molecules. Formation of NaCl·2H(2)O was only detected at temperatures clearly below the peritectic and was first evidenced in a crystallization experiment conducted at 235 K. We have employed the retrieved refractive indices of NaCl·2H(2)O to quantify the temperature dependent partitioning between anhydrous and dihydrate NaCl particles upon crystallization of aqueous NaCl solution droplets. It was found that the temperature range from 235 to 216 K represents the transition regime where the composition of the crystallized particle ensemble changes from almost only NaCl to almost only NaCl·2H(2)O particles. Compared to the findings on the NaCl/NaCl·2H(2)O partitioning from a recent study conducted with micron

  15. Time-resolved infrared reflectance studies of the dehydration-induced transformation of uranyl nitrate hexahydrate to the trihydrate form

    DOE PAGES

    Johnson, Timothy J.; Sweet, Lucas E.; Meier, David E.; ...

    2015-09-08

    Uranyl nitrate is a key species in the nuclear fuel cycle. However, this species is known to exist in different states of hydration, including the hexahydrate ([UO2(NO3)2(H2O)6] often called UNH), the trihydrate [UO2(NO3)2(H2O)3 or UNT], and in very dry environments the dihydrate form [UO2(NO3)2(H2O)2]. Their relative stabilities depend on both water vapor pressure and temperature. In the 1950s and 1960s, the different phases were studied by infrared transmission spectroscopy but were limited both by instrumental resolution and by the ability to prepare the samples for transmission. We have revisited this problem using time-resolved reflectance spectroscopy, which requires no sample preparationmore » and allows dynamic analysis while the sample is exposed to a flow of N2 gas. Samples of known hydration state were prepared and confirmed via X-ray diffraction patterns of known species. In reflectance mode the hexahydrate UO2(NO3)2(H2O)6 has a distinct uranyl asymmetric stretch band at 949.0 cm–1 that shifts to shorter wavelengths and broadens as the sample desiccates and recrystallizes to the trihydrate, first as a shoulder growing in on the blue edge but ultimately results in a doublet band with reflectance peaks at 966 and 957 cm–1. The data are consistent with transformation from UNH to UNT as UNT has two inequivalent UO22+ sites. The dehydration of UO2(NO3)2(H2O)6 to UO2(NO3)2(H2O)3 is both a structural and morphological change that has the lustrous lime green UO2(NO3)2(H2O)6 crystals changing to the matte greenish yellow of the trihydrate solid. As a result, the phase transformation and crystal structures were confirmed by density functional theory calculations and optical microscopy methods, both of which showed a transformation with two distinct sites for the uranyl cation in the trihydrate, with only one in the hexahydrate.« less

  16. Synthesis, characterization and biological study on Cr 3+, ZrO 2+, HfO 2+ and UO 22+ complexes of oxalohydrazide and bis(3-hydroxyimino)butan-2-ylidene)-oxalohydrazide

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; El-Gammal, O. A.; Radwan, H. A.

    2010-09-01

    Cr 3+, ZrO 2+, HfO 2+ and UO 22+ complexes of oxalohydrazide (H 2L 1) and oxalyl bis(diacetylmonoxime hydrazone) [its IUPAC name is oxalyl bis(3-hydroxyimino)butan-2-ylidene)oxalohydrazide] (H 4L 2) have been synthesized and characterized by partial elemental analysis, spectral (IR; electronic), thermal and magnetic measurements. [Cr(L 1)(H 2O) 3(Cl)]·H 2O, [ZrO(HL 1) 2]·C 2H 5OH, [UO 2(L 1)(H 2O) 2] [ZrO(H 3L 2)(Cl)] 2·2H 2O, [HfO(H 3L 2)(Cl)] 2·2H 2O and [UO 2(H 2L 2)]·2H 2O have been suggested. H 2L 1 behaves as a monobasic or dibasic bidentate ligand while H 4L 2 acts as a tetrabasic octadentate with the two metal centers. The molecular modeling of the two ligands have been drawn and their molecular parameters were calculated. Examination of the DNA degradation of H 2L 1 and H 4L 2 as well as their complexes revealed that direct contact of [ZrO(H 3L 2)(Cl)] 2·2H 2O or [HfO(H 3L 2)(Cl)] 2·2H 2O degrading the DNA of Eukaryotic subject. The ligands and their metal complexes were tested against Gram's positive Bacillus thuringiensis (BT) and Gram's negative ( Escherichia coli) bacteria. All compounds have small inhibitory effects.

  17. Stereoretentive formylation of (S)-proline: new application of the self-regeneration of stereo-centres (SRS) principle via chelation to cobalt(III).

    PubMed

    Temizsoy, Mehmet; Sethi, Waqas; Reinholdt, Anders; Schau-Magnussen, Magnus; Bendix, Jesper; Hammershøi, Anders

    2015-11-14

    In a Vilsmeier-Haack-type formylation reaction the α-(dihydroxymethyl)-(S)-prolinato complex (+)578-p-[Co(tren){(RC,SN)-Pro[CH(OH)2]O}]Cl2·2H2O (22) was produced stereoselectively (85% ee) from the (S)-prolinato complex, (+)578-p-[Co(tren){(SC,SN)-ProO}]2(H3O)2(HOEt2)(O3SCF3)7 (18). Similar reaction of the (S)-alaninato complex, (-)578-p-[Co(tren)(S-AlaO)](H3O)(O3SCF3)3 (13), produced the racemate, rac-p-[Co(tren)(Ala{CH(OH)2}O)]SO4·2H2O (17). The contrasting stereochemical outcomes of the formylation reaction with 18versus13 were ascribed to the stereogenic character of the coordinated sec. amine of the (S)-prolinate chelate in 18, which serves to uphold a chiral environment during reaction, whereas reaction intermediates derived from 13 lack this stereochemical feature. The stereoselective formylation of (S)-proline, relying on coordination to an inert metal centre, as conducted here, constitutes a novel application of the concept of Self-Regeneration of Stereocentres (SRS). The α-(hydroxymethyl)-(S)-prolinato complex, (+)578-p-[Co(tren){(RC,SN)-Pro(CH2OH)O}]Cl2·2H2O (23) resulted from borohydride reduction of 22. The molecular structures of (+)578-p-[Co(tren){(RC,SN)-Pro[CH(OH)2]O}]Cl2·2H2O (22), rac-p-[Co(tren)-(Ala{CH(OH)2}O)]I2·H2O (17) and (+)578-p-[Co(tren){(RC,SN)-Pro(CH2OH)O}]Cl2·2H2O (23) were established by X-ray crystallography.

  18. The catalytic effect of water, water dimers and water trimers on H2S + (3)O2 formation by the HO2 + HS reaction under tropospheric conditions.

    PubMed

    Zhang, Tianlei; Yang, Chen; Feng, Xukai; Kang, Jiaxin; Song, Liang; Lu, Yousong; Wang, Zhiyin; Xu, Qiong; Wang, Wenliang; Wang, Zhuqing

    2016-06-29

    In this article, the reaction mechanisms of H2S + (3)O2 formation by the HO2 + HS reaction without and with catalyst X (X = H2O, (H2O)2 and (H2O)3) have been investigated theoretically at the CCSD(T)/6-311++G(3df,2pd)//B3LYP/6-311+G(2df,2p) level of theory, coupled with rate constant calculations by using conventional transition state theory. Our results show that in the presence of catalyst X (X = H2O, (H2O)2 and (H2O)3) into the channel of H2S + (3)O2 formation, the reactions between the SH radical and HO2(H2O)n (n = 1-3) complexes are more favorable than the corresponding reactions of the HO2 radical with HS(H2O)n (n = 1-3) complexes due to the lower barrier of the former reactions and the higher concentrations of HO2(H2O)n (n = 1-3) complexes. Meanwhile, the catalytic effect of water, water dimers and water trimers is mainly taken from the contribution of a single water vapor molecule, since the total effective rate constant of HO2H2O + HS and H2OHO2 + HS reactions was, respectively, larger by 7-9 and 9-12 orders of magnitude than that of SH + HO2(H2O)2 and SH + HO2(H2O)3 reactions. Besides, the enhancement factor of water vapor is only 0.37% at 240 K, while at high temperatures, such as 425 K, the positive water vapor effect is enhanced up to 38.00%, indicating that at high temperatures the positive water effect is obvious under atmospheric conditions. Overall, these results show how water and water clusters catalyze the gas phase reactions under atmospheric conditions.

  19. Four 3D "brick-wall"-like metal-organic frameworks with a flexible ligand of (S,S,R,R)-1,2,3,4-cyclopentanetetracarboxylic acid: crystal structures, luminescent and magnetic properties.

    PubMed

    Cui, Lin; Luan, Xin-Jun; Zhang, Cui-Ping; Kang, Yi-Fan; Zhang, Wen-Tao; Wang, Yao-Yu; Shi, Qi-Zhen

    2013-02-07

    To investigate the conformation of cyclopentanetetracarboxylic acid, four new "brick-wall"-like metal-organic frameworks have been synthesized from hydrothermal reactions with different metal salts, (S,S,R,R)-1,2,3,4-cyclopentanetetracarboxylic acid (H(4)cptc) and auxiliary N-donor ligands, namely, Cu(2)(S,S,R,R-cptc)(bpe)(H(2)O)(2)·2H(2)O (1), Co(2)(S,S,R,R-cptc)(bpe)(0.5)(H(2)O)(2)·2H(2)O (2), Cd(4)(S,S,R,R-cptc)(2)(bpa)(2)(H(2)O)(5)·2H(2)O (3) and Co(2)(S,S,R,R-cptc)(bpy)(0.5)(H(2)O)(2)·2(H(2)O) (4) (bpe = 4-(2-(pyridine-4-yl)vinyl)pyridine, bpa = 4-(2-(pyridine-4-yl)ethyl)pyridine, bpy = 4-(pyridine-4-yl)pyridine). The complexes were further characterized by single-crystal X-ray diffraction, power X-ray diffraction, FT-IR spectra, fluorescent measurements and variable-temperature magnetic susceptibility measurements. The results of the structural investigations show that 1 is a charming (3,3,4)-trinodal architecture, 3 is an interesting trinodal (3,4,5)-connected architecture, and 2 and 4 are isostructural, which are both (4,5)-connected networks. In addition, the magnetic measurements indicate that 2 and 4 show weak antiferromagnetic interactions, and the fluorescent measurement shows the strong solid-state fluorescent emission at room temperature for 3.

  20. Solar-chemical treatment of groundwater contaminated with petroleum at gas station sites: ex situ remediation using solar/TiO(2) photocatalysis and Solar Photo-Fenton.

    PubMed

    Cho, Ii-Hyoung; Kim, Young-Gyu; Yang, Jae-Kyu; Lee, Nae-Hyun; Lee, Seung-Mok

    2006-01-01

    Groundwater samples contaminated by BTEX (benzene, toluene, ethylbenzene, xylene isomers and TPHs (total petroleum hydrocarbons) were treated with advanced oxidation processes (AOPs), such as TiO(2) photocatalysis and Fe(2+)/H(2)O(2) exposed to solar light (37 degrees N and 128 degrees E) with an average intensity of 1.7 mW/cm(2) at 365 nm. These AOP processes showed feasibility in the treatment of groundwater contaminated with BTEX, TPH and TOC (Total Organic Carbon). Outdoor field tests showed that the degradation efficiency of each contaminant was higher in the Fe(2+)/H(2)O(2) system without solar light compared to the TiO(2)/solar light and H(2)O(2)/solar light systems. However, the TiO(2)/solar light and the Fe(2+)/H(2)O(2)/solar light systems showed significantly enhanced efficiencies in the degradation of BTEX, TPH and TOC with the additional use of H(2)O(2). Near complete degradation of BTEX and TPH was observed within 2 and 4 hrs, respectively, however, that of TOC was slower. Without pretreatment of the groundwater, fouling of the TiO(2), due to the ionic species present, was observed within 1 hr of operation, which resulted in the inhibition of further BTEX, TPH and TOC destruction. The degradation rate of n-alkanes with carbon numbers ranging from C10 to C15 was relatively greater than that of n-alknaes with carbon numbers ranging from C16 to C20. From this work, the AOP process (Fe(2+)/H(2)O(2)/solar light and TiO(2)/H(2)O(2)/solar light) illuminated with solar light was identified as an effective ex situ technique in the remediation of groundwater contaminated with petroleum.

  1. catena-Poly[[aquabarium(II)]-mu-aqua-bis(mu-2'-carboxybiphenyl-2-carboxylato)].

    PubMed

    Djehni, Samia; Balegroune, Fadila; Guehria-Laidoudi, Achoura; Dahaoui, Slimane; Lecomte, Claude

    2007-03-01

    In the title compound, [Ba{HOOC(C(6)H(4))(2)CO(2)}(2)(H(2)O)(2)] or [Ba(C(14)H(9)O(4))(2)(H(2)O)(2)], the Ba atoms are coordinated by nine O atoms, six from two 2'-carboxybiphenyl-2-carboxylate (Hbpdc(-)) ligands and three from three coordinated water molecules, resulting in the formation of face-sharing distorted monocapped square antiprisms. The Hbpdc(-) ligands bridge the Ba atoms to form a one-dimensional helical polymer, with a Ba...Ba distance across the chain of 4.1386 (17) A. Adjacent chains are parallel to each other. The two independent ligands are tetradentate and have the same coordination mode, exhibiting mu-oxo bridges and eta(8)-chelation. The crystal structure is further stabilized by hydrogen bonds within each chain.

  2. Crystal structure of bis-{μ2-3-(pyridin-2-yl)-5-[(1,2,4-triazol-1-yl)meth-yl]-1,2,4-triazolato}bis-[aqua-nitrato-copper(II)] dihydrate.

    PubMed

    Doroschuk, Roman

    2016-04-01

    The structure of the dinuclear title complex, [Cu2(C10H8N7)2(NO3)2(H2O)2]·2H2O, consists of centrosymmetric dimeric units with a copper-copper separation of 4.0408 (3) Å. The Cu(II) ions in the dimer display a distorted octa-hedral coordination geometry and are bridged by two triazole rings, forming an approximately planar Cu2N4 core (r.m.s. deviation = 0.049 Å). In the crystal, O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds and π-π inter-actions link the mol-ecules into a three-dimensional network.

  3. Crystal structure of bis­{μ2-3-(pyridin-2-yl)-5-[(1,2,4-triazol-1-yl)meth­yl]-1,2,4-triazolato}bis­[aqua­nitrato­copper(II)] dihydrate

    PubMed Central

    Doroschuk, Roman

    2016-01-01

    The structure of the dinuclear title complex, [Cu2(C10H8N7)2(NO3)2(H2O)2]·2H2O, consists of centrosymmetric dimeric units with a copper–copper separation of 4.0408 (3) Å. The CuII ions in the dimer display a distorted octa­hedral coordination geometry and are bridged by two triazole rings, forming an approximately planar Cu2N4 core (r.m.s. deviation = 0.049 Å). In the crystal, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds and π–π inter­actions link the mol­ecules into a three-dimensional network. PMID:27375870

  4. Effect of hydrogen bonds on optical nonlinearities of inorganic crystals

    NASA Astrophysics Data System (ADS)

    Xue, Dongfeng; Zhang, Siyuan

    1999-03-01

    This work probes the role of hydrogen bonds (such as O-H⋯O and N-H⋯O) in some inorganic nonlinear optical (NLO) crystals, such as HIO 3, NH 4H 2PO 4 (ADP), K[B 5O 6(OH) 4]·2H 2O (KB 5) and K 2La(NO 3) 5·2H 2O (KLN), from the chemical bond standpoint. Second order NLO behaviors of these four typical inorganic crystals have been quantitatively studied, results show hydrogen bonds play a very important role in NLO contributions to the total nonlinearity. Conclusions derived here concerning the effect of hydrogen bonds on optical nonlinearities of inorganic crystals have important implications with regard to the utilization of hydrogen bonds in the structural design of inorganic NLO crystals.

  5. Nanoparticle iron-phosphate anode material for Li-ion battery

    NASA Astrophysics Data System (ADS)

    Son, Dongyeon; Kim, Eunjin; Kim, Tae-Gon; Kim, Min Gyu; Cho, Jaephil; Park, Byungwoo

    2004-12-01

    Nanoparticle crystalline iron phosphates (FePO4•2H2O and FePO4) were synthesized using a (CTAB) surfactant as an anode material for Li rechargeable batteries. The electrochemical properties of the nanoparticle iron phosphates were characterized with a voltage window of 2.4-0 V. A variscite orthorhombic FePO4•2H2O showed a large initial charge capacity of 609mAh/g. On the other hand, a tridymite triclinic FePO4 exhibited excellent cyclability: the capacity retention up to 30 cycles was ˜80%, from 485 to 375mAh/g. The iron phosphate anodes exhibited the highest reported capacity, while the cathode LiFePO4 has an ideal capacity of 170mAh/g.

  6. Photocatalytic and luminescent properties of three novel complexes based on a pyridine-pyrimidine-hydrazone ligand

    NASA Astrophysics Data System (ADS)

    Xu, Zhouqing; Mao, Xianjie; Zhang, Peiling; Li, Huijun; Wang, Yuan; Liu, Miaomiao; Jia, Lei

    2017-01-01

    Three novel complexes, namely {[Zn3(L)2(SO4)2(H2O)4]·2H2O}n (1), {[Cd(L)(OAc)]}n (2) and [Hg2(L)(I)3]2 (3) (HL = N‧ - isonicotinoylpyrimidine -2- carbohydrazonamide), have been synthesized and characterized by elemental analyses, infrared spectra and single-crystal X-ray diffraction analyze. The 1D complex 1 and complex 2, and the binuclear complex 3 are expanded to 3D networkers by the strong hydrogen bonds and π-π stacking interactions. The photocatalytic degradation of methylene blue (MB) results indicate that complexes 1-3 are excellent candidates as photocatalysts in decomposing MB with the presence of H2O2. In addition, the luminescent properties of these three complexes have been studied in the solid state.

  7. Lead(II) coordination polymers based on rigid-flexible 3,5-bis-oxyacetate-benzoic acid: Structural transition driven by temperature control

    NASA Astrophysics Data System (ADS)

    Chen, Yong-Qiang; Tian, Yuan

    2017-03-01

    Three Pb(II) complexes {[Pb3(BOABA)2(H2O)]·H2O}n (1), {[Pb4(BOABA)2(μ4-O)(H2O)2]·H2O}n (2), and [Pb3(BOABA)2(H2O)]n (3) (H3BOABA=3,5-bis-oxyacetate-benzoic acid) were obtained under the same reaction systems with different temperatures. Complexes 1 and 2 are two dimensional (2D) networks based on Pb-BOABA chains and Pb4(μ4-O)(COO)6 SBUs, respectively. Complex 3 presents an interesting three dimensional (3D) framework, was obtained by increasing the reaction temperature. Structural transition of the crystallization products is largely dependent on the reaction temperature. Moreover, the fluorescence properties of complexes 1-3 have been investigated.

  8. Bis(tetra-ethyl-ammonium) oxalate dihydrate.

    PubMed

    McNeese, Timothy J; Pike, Robert D

    2012-08-01

    The title compound, 2C(8)H(20)N(+)·C(2)O(4) (2-)·2H(2)O, synthesized by neutralizing H(2)C(2)O(4)·2H(2)O with (C(2)H(5))(4)NOH in a 1:2 molar ratio, is a deliquescent solid. The oxalate ion is nonplanar, with a dihedral angle between carboxyl-ate groups of 64.37 (2)°. O-H⋯O hydrogen bonds of moderate strength link the O atoms of the water mol-ecules and the oxalate ions into rings parallel to the c axis. The rings exhibit the graph-set motif R(4) (4)(12). In addition, there are weak C-H⋯O inter-actions in the crystal structure.

  9. Bis(tetra­ethyl­ammonium) oxalate dihydrate

    PubMed Central

    McNeese, Timothy J.; Pike, Robert D.

    2012-01-01

    The title compound, 2C8H20N+·C2O4 2−·2H2O, synthesized by neutralizing H2C2O4·2H2O with (C2H5)4NOH in a 1:2 molar ratio, is a deliquescent solid. The oxalate ion is nonplanar, with a dihedral angle between carboxyl­ate groups of 64.37 (2)°. O—H⋯O hydrogen bonds of moderate strength link the O atoms of the water mol­ecules and the oxalate ions into rings parallel to the c axis. The rings exhibit the graph-set motif R 4 4(12). In addition, there are weak C—H⋯O inter­actions in the crystal structure. PMID:22904842

  10. Dehydration-driven evolution of topological complexity in ethylamonium uranyl selenates

    NASA Astrophysics Data System (ADS)

    Gurzhiy, Vladislav V.; Krivovichev, Sergey V.; Tananaev, Ivan G.

    2017-03-01

    Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C2H8N)2[(UO2)(SeO4)2(H2O)](H2O) (I), (C2H8N)3[(UO2)(SeO4)2(HSeO4)] (II), (C2H8N)[(UO2)(SeO4)(HSeO3)] (III), and (C2H8N)(H3O)[(UO2)(SeO4)2(H2O)] (IV) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H2O content.

  11. Syntheses, characterization and DNA-binding studies of ruthenium(II) terpyridine complexes: [Ru(tpy)(PHBI)]2+ and [Ru(tpy)(PHNI)]2+.

    PubMed

    Jiang, Cai-Wu; Chao, Hui; Li, Hong; Ji, Liang-Nian

    2003-01-15

    Two novel tridentate ligands, 2-(2-benzimidazole)-1,10-phenanthroline (PHBI) and 2-(2-naphthoimidazole)-1,10-phenanthroline (PHNI), and their heteroleptic complexes [Ru(tpy)(PHBI)](ClO(4))(2).2H(2)O (1) and [Ru(tpy)(PHNI)](ClO(4))(2).H(2)O (2) (tpy=2,2':6',2"-terpyridyl) have been synthesized and characterized by elemental analysis, mass spectra, 1H NMR, and electronic spectroscopy. The electrochemical behaviors of the two novel complexes were studied by cyclic voltammetry. The DNA-binding properties of the two complexes were investigated by spectroscopic methods and viscosity measurements. The results indicated that the two complexes interact with DNA in different binding modes. Complex 1 may bind to DNA via electrostatic interaction, while complex 2 binds to DNA by partial intercalation via the extended naphthyl ring into the base pairs of DNA.

  12. Behavior and products of mechano-chemical dechlorination of polyvinyl chloride and poly (vinylidene chloride).

    PubMed

    Xiao, Xiao; Zeng, Zigao; Xiao, Songwen

    2008-02-28

    The mechano-chemical (MC) dechlorination of polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) was performed by mechanical milling PVC/PVDC powder with zinc powder in a planetary ball mill, and the products of dechlorination were characterized by Infrared spectra (IR), X-ray diffraction (XRD), Raman spectroscopy, gas chromatography-mass spectrometry (GC-MS), and 13C solid-state nuclear magnetic resonance (NMR). The experimental results show that PVC/PVDC can be easily dechlorinated by milling with zinc powder, and formed various kinds of inorganic and organic products. Inorganic compounds included Zn2OCl(2).2H2O, Zn5(OH)8Cl2.H2O etc., and organic products involved diamond-like carbon, carbyne fragment, polyacetylene etc. Organic products formed following the paths of dechlorination, dehydrochlorination, crosslink, and oxidation. The mechano-chemical dechlorination process of PVC/PVDC may be an effective approach for carbyne synthesizing in the appropriate condition.

  13. catena-Poly[[[aqua-bis-(1H-imidazole-κN(3))copper(II)]-μ-furan-2,5-di-car-boxylato-κ(2)O(2):O(5)] trihydrate].

    PubMed

    Li, Ya-Feng; Xu, Yue; Qin, Xiao-Lin; Gao, Wen-Yuan; Gao, Yue

    2012-05-01

    In the title cooridnation polymer, {[Cu(C(6)H(2)O(5))(C(3)H(4)N(2))(2)(H(2)O)]·3H(2)O}(n), an infinite chain is formed along [001] by linking of the Cu(C(3)N(2)H(4))(2)(H(2)O) entities with two bridging monodentate carboxyl-ate groups of two different furan-2,5-dicarboxyl-ate dianions. The geometry of the Cu(2+) ion is a square-based pyramid with the water atom in the apical position and the ligand O and N atoms in a trans orientation. The dihedral angle between the imidazole planes is 83.96 (14)°. O(w)-H⋯O and N(i)-H⋯O (w = water and i = imidazole) hydrogen bonds help to establish the packing.

  14. Synthesis of ZnO, SnO2 nanoparticles and preparation of ZnO-SnO2 nanocomposites.

    PubMed

    Gultekin, Deniz; Alaf, Mirac; Guler, Mehmet Oguz; Akbulut, Hatem

    2012-12-01

    This article reports the preparation of ZnO-SnO2 nanocomposites from ZnO and SnO2 nanoparticles produced by homogenous precipitation route. Zinc acetate dihydrate (Zn(CH3COO)2 x 2H2O) and tin(II) chloride dehydrates (SnCl2. 2H2O) have been used as precursors. Distilled water was used as a solvent, monoethanolamine (MEA) is used as sol stabilizer. Precursors individually dissolved and stirred at 60 degrees C for 1 h. Certain amount of MEA were added to solution and stirred for 2 h. Then solution was cooled to room temperature and gets precipitated. The collected nanosized precipitates were mixed together and deposited on glass substrates by drain coating and post-heated at different temperatures. X-ray diffractometer was used to determine preferred crystal orientation and particle size of the thin films. Morphologies of nanopowders were examined by scanning electron microscope (SEM).

  15. Possible sources of H2 to H2O enrichment at evaporation of parent chondritic material

    NASA Technical Reports Server (NTRS)

    Makalkin, A. B.; Dorofeyeva, V. A.; Vityazev, A. V.

    1993-01-01

    One of the results obtained from thermodynamic simulation of recondensation of the source chondritic material is that at 1500-1800 K it's possible to form iron-rich olivine by reaction between enstatite, metallic iron and water vapor in the case of (H2O)/(H2) approximately equal to 0.1. This could be reached if the gas depletion in hydrogen is 200-300 times relative to solar abundance. To get this range of depletion one needs some source material more rich in hydrogen than the carbonaceous CI material which is the richest in volatiles among chondrites. In the case of recondensation at impact heating and evaporation of colliding planetesimals composed of CI material, we obtain insufficiently high value of (H2)/(H2O) ratio. In the present paper we consider some possible source materials and physical conditions necessary to reach gas composition with (H2)/(H2O) approximately 10 at high temperature.

  16. Synthesis, characterizations and catalytic studies of a new two-dimensional metal-organic framework based on Co-carboxylate secondary building units

    NASA Astrophysics Data System (ADS)

    Bagherzadeh, Mojtaba; Ashouri, Fatemeh; Đaković, Marijana

    2015-03-01

    A metal-organic framework [Co3(BDC)3(DMF)2(H2O)2] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P21/n space group with a=13.989(3) Å, b=9.6728(17) Å, c=16.707(3) Å, and Z=2. The polymer features a framework based on the perfect octahedral Co-O6 secondary building units. The catalytic activities of [Co3(BDC)3(DMF)2(H2O)2]n for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant degradation in catalytic activity. Furthermore, no contribution from homogeneous catalysis of active species leaching into reaction solution was detected.

  17. Metal chelates as anti-cancer agents. II cytotoxic action of palladium and platinum complexes of 6-mercaptopurine and thioguanine.

    PubMed

    Das, M; Livingstone, S E

    1978-08-01

    The metal complexes Pd(MP)2.2H2O, Pt(MP)2H2O (MPH=6-mercaptopurine), Pt(AMP2.3H2O and Pd3(AMP)4Cl2(AMPH).4H2O (AMPH=thioguanine) have been isolated. They were screened for anti-tumour activity in the L-1210 lymphoid leukaemia test system in mice. All 4 show marked anti-tumour activity, the complex Pt(AMP)2.3H2O giving a T/C of 185 at the optimum dosage. However, the anti-tumour activity of the metal complexes is somewhat less than that shown by the parent purines under the same conditions.

  18. Crystal structure of catena-poly[[copper(II)-μ2-salicylato-[diaqua­copper(II)]-μ2-salicylato] dihydrate

    PubMed Central

    van der Horn, Jitschaq A.; Lutz, Martin

    2017-01-01

    The title compound, {[Cu2(C7H4O3)2(H2O)2]·2H2O}n, contains two copper(II) cations in special positions (one on a twofold rotation axis and one on an inversion centre) and the the salicylate ligand in its dianionic form. By four- and six-coordinate metal coordination, chains are formed parallel to [001], which are extended by O—H⋯O hydrogen bonding into sheets extending parallel to (100). These sheets are weakly connected by O—H⋯O hydrogen bonding via the non-coordinating lattice water mol­ecules into a three-dimensional network. PMID:28217350

  19. Generic Rapid Analysis of Current and Prospective Nerve Agents and Their Degradation Products

    DTIC Science & Technology

    2005-10-01

    CoCl2 6H2O, 0.1g ZnSO4 7H2O, 20 mg H3BO3, 10 mg Na2MoO4 2H2O , 10 mg CuSO4 per liter) 4.2 ml 20% glucose, 2.3 ml 40% Na citrate, 2.3 ml 40% K gluconate...FeSO4 H2O, 1.67 ml Salts (6.0 g MgCO4 7H2O, 3.0 g nitrilotriacetic acid, 1.0 g NaCl, 1.0 g MnSO4 H2O, 0.5 g FeSO4 7H2O, 0.1 g CaCl2 2H2O , 0.1 g

  20. Fe(0)-Based-Bioremediation of RDX-Contaminated Groundwater

    DTIC Science & Technology

    2004-01-15

    10-3), CuSO4 •5H20 (1.50 × 10-3), ZnSO4•7H20 (1.73 × 10-3), CoSO4•7H20 (1.69 × 10-3), (NH4)6Mo7O24 (1.06 × 10-3). The medium was buffered with...4H2 + 2CO2 → CH3COO- + H+ + 2H2O (Eq. 1) Note that H2 could be provided by the anaerobic corrosion of iron with...water: Fe0 + 2H2O → H2 +Fe+2 + 2OH- (Eq. 2) In theory, such homoacetogens could comensalistically

  1. Biotransformation of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) by Denitrifying Pseudomonas sp. Strain FA1

    DTIC Science & Technology

    2003-09-01

    CoCl26H2O, 0.15 g of ZnCl2, 0.01 g of CuSO4 5H2O, 0.10 g of FeSO47H2O, 0.05 g of Na2MoO4, 0.05 g of NiCl26H2O, and 0.05 g of Na2WO4 2H2O . A...solution was used as the trace element solution and was composed of (per liter of deionized water) 0.20 g of MnSO4H2O, 0.10 g of CaCl2 2H2O , 0.10 g of

  2. Furthering the Enzymatic Destruction of Nerve Agents

    DTIC Science & Technology

    2002-01-01

    0.1 mg of CoCl2⋅6H2O, 0.1 mg of ZnSO4⋅7H2O, 0.02 mg of H3BO3, 0.01 mg of Na2MoO4⋅ 2H2O , 0.01 mg of CuSO4 , and 1 g of O O...mg of thiamine, 6 mg of MgSO4⋅7H2O, 3 mg of nitrilotriacetic acid, 48 mg of K2SO4, 1 mg of MnSO4⋅H2O, 2.8 mg of FeSO4⋅7H2O, 0.1 mg of CaCl2⋅ 2H2O

  3. Batch and High Cell Density Fed-Batch Culture Productions of an Organophosphorus Hydrolase

    DTIC Science & Technology

    2002-01-01

    0.02 g H3BO3, 0.01 g NaMoO4@ 2H2O , and 0.01 g CuSO4 . Fed-Batch Fermentations were carried out in the same Bio-Flow 3000 unit fitted with 10 L...per L): 3.0 g nitrilotriacetic acid, 6.0 MgSO4@7H2O, 1.0 g NaCl, 1.0 g MnSO4@H2O, 0.5 g FeSO4@7H20, 0.1 CaCl2@ 2H2O , 0.1 CoCl2@6H2O, 0.1 g ZnSO4@7H2O

  4. Two new coordination polymers with flexible alicyclic carboxylate and bipyridyl co-ligands bearing trinuclear [Ni3(COO)6] SBUs: Synthesis, crystal structures, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Zhu, Xian-Dong; Li, Yong; Gao, Jian-Gang; Wang, Fen-Hua; Li, Qing-Hai; Yang, Hong-Xun; Chen, Lei

    2017-02-01

    Two new coordination polymers generally formulated as [Ni3(Hchda)2(chda)2(bpy)2(H2O)2]n (1) and [Ni3(Hchda)2(chda)2(bpp)2(H2O)2]n (2) [H2chda = 1,1'-cyclohexanediacetic acid, bpy = 4,4'-bipyridine and bpp = 1,3-bis(4-pyridyl)propane], have been successfully assembled through mixed-ligands synthetic strategy with flexible alicyclic carboxylate and bipyridyl ligands. There structures feature trinuclear nickel secondary building units connected via the bridging bipyridyl spacers to form two-dimensional (4,4) grid layer. The nature of the different N-donor auxiliary ligands leads to the discrepancy in supramolecular structure of the two compounds. Magnetic studies indicate the ferromagnetic intra-complex magnetic interaction in the molecule for 1 and 2.

  5. Gaseous sodium sulfate formation in flames and flowing gas environments

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Miller, R. A.; Kohl, F. J.; Fryburg, G. C.

    1977-01-01

    Formation of Na2SO4(g) in flames and hot flowing gas systems was studied by high pressure, free-jet expansion, modulated molecular beam mass spectrometric sampling. Fuel-lean CH4-O2 flames doped with SO2, H2O and NaCl yielded the gaseous Na2SO4 molecule in residence times of less than one millisecond. Intermediate species NaSO2(g) and NaSO3(g) were also observed and measured. Composition profiles were obtained for all reaction products. Nonflame flowing gas experiments showed that Na2SO4 and NaSO3 gaseous molecules were formed at 1140 C in mixtures of O2, H2O(g), SO2 and NaCl(g). Experimental results are compared with calculated equilibrium thermodynamic predictions.

  6. Electrodeposition of nanostructured Sn-Zn coatings

    NASA Astrophysics Data System (ADS)

    Salhi, Y.; Cherrouf, S.; Cherkaoui, M.; Abdelouahdi, K.

    2016-03-01

    The electrodeposition of Sn-Zn coating at ambient temperature was investigated. The bath consists of metal salts SnCl2·2H2O and ZnSO4·7H2O and sodium citrate (NaC6H5Na3O7·2H2O) as complexing agent. To prevent precipitation, the pH is fixed at 5. Reducing tin and zinc through Sncit2- and ZnHcit- complex respectively is confirmed by the presence of two cathodic peaks on the voltammogram. The kinetic of tin (II) reduction process is limited by the SnCit2- dissociation. The SEM and TEM observations have showed that the coating consists of a uniform Sn-Zn layer composed of fine grains on which tin aggregates grow up. XRD revealed peaks corresponding to the hexagonal Zn phase and the tetragonal β-Sn phase.

  7. Removal of color substances using photocatalytic oxidation for membrane filtration processes.

    PubMed

    Tay, J H; Chen, D; Sun, D D

    2001-01-01

    This study aims to remove the color substances, which normally cause difficulties in membrane filtration processes due to fouling using heterogeneous UV/TiO2/H2O2 reactor. It is confirmed that the technique used in this study was effective to remove TOC at 38% and color400 at 89% within 150-min irradiation. The experiment results showed that low concentrations of hydrogen peroxide dosage (less than 0.016 M) to UV/TiO2 system accelerated the TOC and Color400 removal rate from 9% to 38% and 40% to 89% respectively, while over-dosage made this positive effect decline. The humic acid solution treated by photo catalytic oxidation in UV/TiO2/H2O2 reactor did not change the zeta potential on membrane surface and membrane rejection rate.

  8. Diaqua­bis­{2-hy­droxy-5-[(pyridin-2-yl)methyl­idene­amino]­benzoato-κ2 N,N′}nickel(II) dihydrate

    PubMed Central

    Zha, Meiqin; Li, Xing; Bing, Yue; Luo, Zhengbing

    2010-01-01

    In the title complex, [Ni(C13H9N2O3)2(H2O)2]·2H2O, the NiII atom, located on a twofold rotation axis, is in a distorted octa­hedral geometry, defined by four N atoms from two 2-hy­droxy-5-[(pyridin-2-yl)methyl­idene­amino]­benzoate ligands and two O atoms from two water mol­ecules. In the crystal, inter­molecular O—H⋯O hydrogen bonds link the complex mol­ecules and uncoordinated water mol­ecules into a three-dimensional network. Intra­molecular O—H⋯O hydrogen bonds are present between the hy­droxy and carboxyl­ate groups. PMID:21589257

  9. Rietveld refinement of a natural cobaltian mansfieldite from synchrotron data

    PubMed Central

    Zoppi, Matteo; Pratesi, Giovanni

    2009-01-01

    A structural refinement of a natural sample of a Co-bearing mansfieldite, AlAsO4·2H2O [aluminium orthoarsenate(V) dihydrate], has been performed based on synchrotron powder diffraction data, with 5% of the octa­hedral Al sites replaced by Co. Mansfieldite is the aluminium analogue and an isotype of the mineral scorodite (FeAsO4·2H2O), with which it forms a solid solution. The framework structure is based on AsO4 tetra­hedra sharing their vertices with AlO4(H2O)2 octa­hedra. Three of the four H atoms belonging to the two water mol­ecules in cis positions take part in O—H⋯O hydrogen bonding. PMID:21581741

  10. A Theoretical Study of the Interaction of Water and Imidazole with Iron and Nickel Dications

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschliches, Charles W., Jr.; Carroll, Carol W. (Technical Monitor)

    2001-01-01

    The structures, the harmonic frequencies, and the energies of Fe2+(H2O)n(imid)m and Ni2+(H2O)n(imid)m complexes are computed using density functional theory with the B3LYP functional. A CSOV analysis shows that the bonding is mostly electrostatic in nature. Imidazole forms a stronger bond than water with both metal dications due to its larger dipole moment and polarizability. The reactions for the exchange of one water molecule by one imidazole are exothermic and up to six water molecules can be replaced by imidazoles. The trends are very similar for both metals with the displacement reactions being slightly more favorable for Ni(2+).

  11. Complementary in situ reactivity of isomeric dipyridylamide precursors and its effect on dimensionality of cadmium 5-nitroisophthalate coordination polymers

    NASA Astrophysics Data System (ADS)

    O'Donovan, Megan E.; LaDuca, Robert L.

    2014-07-01

    Hydrothermal treatment of cadmium nitrate, 5-nitroisophthalic acid (H2nip) and one of two isomeric dipyridylamides resulted in coordination polymer crystalline solids that manifested different in situ reactivity and dimensionality, as ascertained by single crystal X-ray diffraction. Hydrolysis of 3-pyridylisonicotinamide (3-pina) afforded the 3-aminopyridine (3-ampyr) ligands observed in the 1-D ladder polymer {[Cd(nip)(3-ampyr)(H2O)]ṡ2H2O}n (1). Conversely, hydrolysis of the isomeric precursor 3-pyridylnicotinamide (3-pna) generated the monoanionic nicotinate ligands in the 2-D coordination polymer [Cd2(nip)(nic)2(H2O)2]n (2). Compound 2 displays {Cd2(OCO)2} eight-membered ring dimeric units linked into (6,3) graphite-type slab motifs. Luminescent properties of these two new materials are also presented.

  12. Coordination of metronidazole to Cu(II): Structural characterization of a mononuclear square-planar compound

    NASA Astrophysics Data System (ADS)

    Palmer, Joshua H.; Wu, Ja-Shin; Upmacis, Rita K.

    2015-07-01

    The reaction bet