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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. EPR of Cu 2+ and VO 2+ in a cobalt saccharin complex, [Co(sac) 2(H 2O) 4]·2H 2O, single crystals

    NASA Astrophysics Data System (ADS)

    Yerli, Y.; Köksal, F.; Karadag, A.

    2003-09-01

    Cu 2+ and VO 2+ doped single crystals of [Co(sac) 2(H 2O) 4]·2H 2O (Cosacaqua) complex were investigated using EPR technique at ambient temperature. Detailed investigation of the EPR spectra indicated that the Cu 2+ and VO 2+ substitute the Co 2+. Two sites were observed for Cu 2+ and VO 2+. But each site of V 4+ corresponds two different orientations of VO 2+. The principal values of the g and the hyperfine tensors were obtained. The spectra indicate that the ground state for Cu 2+ is mainly 3 dx2- y2. The covalent bonding parameters for Cu 2+ and VO 2+ and Fermi contact terms were obtained.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. CO2-H2O based pretreatment and enzyme hydrolysis of soybean hulls.

    PubMed

    Islam, S M Mahfuzul; Li, Qian; Loman, Abdullah Al; Ju, Lu-Kwang

    2017-11-01

    The high carbohydrate content of soybean hull makes it an attractive biorefinery resource. But hydrolyzing its complex structure requires concerted enzyme activities, at least cellulase, xylanase, pectinase and α-galactosidase. Effective pretreatment that generates minimal inhibitory products is important to facilitate enzymatic hydrolysis. Combined CO2-H2O pretreatment and enzymatic hydrolysis by Aspergillus niger and Trichoderma reesei enzyme broths was studied here. The pretreatment was evaluated at 80°C-180°C temperature and 750psi-1800psi pressure, with fixed moisture content (66.7%) and pretreatment time (30min). Ground hulls without and with different pretreatments were hydrolyzed by enzyme at 50°C and pH 4.8 and compared for glucose, xylose, galactose, arabinose, mannose and total reducing sugar release. CO2-H2O pretreatment at 1250psi and 130°C was found to be optimal. Compared to the unpretreated hulls hydrolyzed with 2.5-fold more enzyme, this pretreatment improved glucose, xylose, galactose, arabinose and mannose releases by 55%, 35%, 105%, 683% and 52%, respectively. Conversions of 97% for glucose, 98% for xylose, 41% for galactose, 59% for arabinose, 87% for mannose and 89% for total reducing sugar were achieved with Spezyme CP at 18FPU/g hull. Monomerization of all carbohydrate types was demonstrated. At the optimum pretreatment condition, generation of inhibitors acetic acid, furfural and hydroxymethylfurfural (HMF) was negligible, 1.5mg/g hull in total. The results confirmed the effective CO2-H2O pretreatment of soybean hulls at much lower pressure and temperature than those reported for biomass of higher lignin contents. The lower pressure requirement reduces the reactor cost and makes this new pretreatment method more practical and economical. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Water dependence of the HO2 self reaction: kinetics of the HO2-H2O complex.

    PubMed

    Kanno, Nozomu; Tonokura, Kenichi; Tezaki, Atsumu; Koshi, Mitsuo

    2005-04-14

    Transient absorption spectra and decay profiles of HO2 have been measured using cw near-IR two-tone frequency modulation absorption spectroscopy at 297 K and 50 Torr in diluent of N2 in the presence of water. From the depletion of the HO2 absorption peak area following the addition of water, the equilibrium constant of the reaction HO2 + H2O <--> HO2-H2O was determined to be K2 = (5.2 +/- 3.2) x 10(-19) cm3 molecule(-1) at 297 K. Substituting K2 into the water dependence of the HO2 decay rate, the rate coefficient of the reaction HO2 + HO2-H2O was estimated to be (1.5 +/- 0.1) x 10(-11) cm3 molecule(-1) s(-1) at 297 K and 50 Torr with N2 as the diluent. This reaction is much faster than the HO2 self-reaction without water. It is suggested that the apparent rate of the HO2 self-reaction is enhanced by the formation of the HO2-H2O complex and its subsequent reaction. Results are discussed with respect to the kinetics and atmospheric chemistry of the HO2-H2O complex. At 297 K and 50% humidity, the concentration ratio of [HO2-H2O]/[HO2] was estimated from the value of K2 to be 0.19 +/- 0.11.

  20. 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

  1. Solid state synthesis, spectroscopic and X-ray studies of metal complexes of 2-picolinic acid and vapochromic behavior of [Co(Pic)2(H2O)2]·2H2O

    NASA Astrophysics Data System (ADS)

    Tella, Adedibu C.; Oladipo, Adetola C.; Adeyemi, Olalere G.; Oluwafemi, Oluwatobi S.; Oguntoye, Stephen O.; Alimi, Lukman O.; Ajayi, Joseph T.; Degni, Sylvestre K.

    2017-06-01

    Three compounds, [Cu(Pic)2(H2O)] (1a), [M(Pic)2(H2O)2]·2H2O] (M=Co (2a), Zn (3a), Pic = 2-picolinic acid) were obtained by solvent-free synthesis through grinding of metal acetate salt with 2-picolinic acid. Favorable comparison of solvent-free with solution based method of 1b, 2b and 3b was observed. Good resemblance of identity of compounds obtained through the two methods was confirmed by elemental analysis, spectroscopic techniques (UV-Vis and FTIR), TGA and PXRD. The single crystal diffraction data for [Co(Pic)2(H2O)2]·2H2O obtained from the Cambridge structure database (CSD), its PXRD simulated patterns closely matched that of complex 2a by solvent-free synthesis. Vapochromic behavior of this complex was studied using colour change, FT-IR, TGA, PXRD and solid state UV-visible spectroscopies. This complex generated specific colour which is also evident in the shifting of the vibrational frequencies (νO-H and ν C=O bands). The resulting inclusion compounds have different colours depending on the solvent used. In addition, exposure of the resultant inclusion compounds to ambient environment or heating for a few minutes regenerate the original material without degradation even after exposure/heating cycles as evident from TGA/DTG thermograms.

  2. 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.

  3. 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

  4. In vitro formation of dicalcium phosphate dihydrate, CaHPO4 . 2H2O (DCPD).

    PubMed

    LeGeros, R Z; Lee, D; Quirolgico, G; Shirra, W P; Reich, L

    1983-01-01

    Dicalcium phosphate dihydrate, CaHPO4 . 2H2O (DCPD) crystals were grown in solutions and in different types of gels (silica, agar, collagen) at different pH's, in the presence of other ions, and on different Ca-bearing substrates (enamel, dentine, bone, calcite). Hydrolysis of DCPD to other calcium phosphates and calcium oxalates were made in solutions containing different ions at 37 degrees C, 24h. Results showed that the type of media (solution or gel), type of gel, pH, presence of other ions affect the morphology (size/shape) and growth of DCPD. In systems of changing pH, the more basic calcium phosphate (e.g., apatite, OCP) formed in the first zone, DCPD in the last zone, regardless of the initial Ca/P of the system. Growth of DCPD was suppressed in the presence of F-(which favored growth of apatite), of Cd2+, Pb2+ (which favored OCP). Hydrolysis of DCPD to apatite was promoted in solutions containing Ca2+, F-, CO3=, and inhibited by Mg2+, P2O74-. Hydrolysis of DCPD to calcium oxalate occurs in presence of C2O4=. Results indicate that the variation in morphology of DCPD occurring in various human tissue calcinosis and the co-existence of DCPD with other calcium phosphates and oxalates in urinary and dental calculi are due to variations in pH, and presence of different ions in the media.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Microwave CVD Thick Diamond Film Synthesis Using CH4/H2/H2O Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Man, Weidong; Wang, Jianhua; Wang, Chuanxin; Ma, Zhibin; Wang, Shenggao; Xiong, Liwei

    2006-05-01

    Thick diamond films with a thickness of up to 1.2 mm and a area of 20 cm2 have been grown in a homemade 5 kW microwave plasma chemical vapor deposition (MPCVD) reactor using CH4/H2/H2O gas mixtures. The growth rate, radial profiles of the film thickness, diamond morphology and quality were evaluated with a range of parameters such as the substrate temperature of 700 oC to 1100 oC, the fed gas composition CH4/H2 = 3.0%, H2O/H2 = 0.0%~ 2.4%. They were characterized by scanning electron microscopy and Raman spectroscopy. Translucent diamond wafers have been produced without any sign of non-diamond carbon phases, Raman peak as narrow as 4.1 cm-1. An interesting type of diamond growth instability under certain deposition conditions was observed in a form of accelerated growth of selected diamond crystallites of a very big lateral size, about 1 mm, and of a better structure compared to the rest of the film.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

    Park, J. H.; Carli, B.

    1991-01-01

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

  12. 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.

  13. Quantifying CO2, H2O, and CH4 fluxes over an intermittently- irrigated rice paddy

    NASA Astrophysics Data System (ADS)

    Hwang, Y.; Ryu, Y.; Kang, M.; Choi, S.; Kim, H.

    2016-12-01

    Rice is a major staple food for more than three billion people. However, growing rice consumes substantial amount of water and emits methane fluxes. In this study, we report 1.5 year observation of CO2, H2O and CH4 fluxes measured using an eddy covariance system in an intermittently-irrigated paddy rice in South Korea. On an annual scale (May 2015 through Apr 2016), the paddy rice site acted as CO2 sink (-168 gC m-2 yr-1) with 685 gC m-2 yr-1 and 517 gC m-2 yr-1 for GPP and Reco, respectively. Rice yield was 8.08 ton ha-1 which is two-fold of mean global rice yield. Annual CH4 emission was 15 gC m-2 yr-1, which is comparable to the other paddy rice sites in California, Japan, and India. CH4 emissions were dominant during daytime in irrigated period, and during nighttime in drained period. Annual evaporation was 585 mm yr-1, with rapid increase after irrigation. In 2016, irrigation and transplanting timings were two weeks earlier than 2015. However, the earlier activities did not lead earlier green-up. The timings of increase in GPP were almost identical between the two years, indicating that water loss via evaporation was unnecessarily made. The results highlight that an integrated management strategy is required to reduce CH4 emission, increase yield, and reduce evaporation loss.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Mechanistic analysis of water oxidation catalyst cis-[Ru(bpy)2(H2O)2]2+: Effect of dimerization

    DOE PAGES

    Erdman, Darren; Pineda-Galvan, Yuliana; Pushkar, Yulia

    2017-01-25

    While the catalytic activity of some Ru-based polypyridine complexes in water oxidation is well established, the relationship between their chemical structure and activity is less known. In this work, the single site Ru complex [Ru(bpy)2(H2O)2]2+ (bpy = 2,20-bipyridine)—which can exist as either a cis isomer or a trans isomer—is investigated. While a difference in the catalytic activity of these two isomers is well established, with cis-[Ru(bpy)2(H2O)2]2+ being much more active, no mechanistic explanation of this fact has been presented. The oxygen evolving capability of both isomers at multiple concentrations has been investigated, with cis-[Ru(bpy)2(H2O)2]2+ showing a second-order dependence of O2more » evolution activity with increased catalyst concentration. Measurement of the electron paramagnetic resonance (EPR) spectrum of cis-[Ru(bpy)2(H2O)2]2+, shortly after oxidation with CeIV, showed the presence of a signal matching that of cis,cis-[RuIII(bpy)2(H2O)ORuIV(bpy)2(OH)]4+, also known as “blue dimer”. The formation of dimers is a concentration-dependent process, which could serve to explain the greater than first order increase in catalytic activity. The trans isomer showed a first-order dependence of O2 evolution on catalyst concentration. As a result, behavior of [Ru(bpy)2(H2O)2]2+ isomers is compared with other Ru-based catalysts, in particular [Ru(tpy)(bpy)(H2O)]2+ (tpy = 2,20;6,20 0-terpyridine).« less

  19. 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).

  20. BTKh-26 STRUKTURA (Luch-2) Hardware

    NASA Image and Video Library

    2012-06-30

    ISS032-E-005012 (30 June 2012) --- Russian cosmonaut Sergei Revin, Expedition 32 flight engineer, is pictured near Russian biotechnology experiment BTKh-26 STRUKTURA (Luch-2) hardware floating freely in the Zvezda Service Module of the International Space Station.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  2. Elementary reaction modeling of CO2/H2O co-electrolysis cell considering effects of cathode thickness

    NASA Astrophysics Data System (ADS)

    Li, Wenying; Shi, Yixiang; Luo, Yu; Cai, Ningsheng

    2013-12-01

    A one-dimensional elementary reaction model of CO2/H2O co-electrolysis in solid oxide electrolysis cell (SOEC) coupled with heterogeneous elementary reactions, electrochemical reactions, electrode microstructure, and the transport of mass and charge is developed in this paper. This model, validated with the experimental performance of H2O electrolysis, CO2 electrolysis and CO2/H2O co-electrolysis at 700 °C, is demonstrated to be a useful tool for understanding the intricate reaction and transport processes within SOEC electrode and the electrode structure design and optimization. The simulation results indicate that the heterogeneous reactions reach the equilibrium near the cathode outside surface, and the electrochemical reactions mainly occur in the electrode near the electrode-electrolyte interface. The main zone of electrochemical reactions is far enough from the main zone of heterogeneous reactions, so that the two kinds of reactions almost don't influence each other when the cathode is thick enough (e.g. 700 μm). While, as the cathode thickness reduces, the zones of electrochemical reactions and the non-equilibrium heterogeneous reactions overlap each other, and the electrochemical performance of CO2/H2O co-electrolysis is affected by the variations of elementary species concentrations of O(Ni) and (Ni) due to the heterogeneous reactions. The model successfully explains the experimental phenomenon that the polarization curve of CO2/H2O electrolysis lies between that of H2O and CO2 electrolysis in a cathode supported SOEC, but almost the same as that of H2O electrolysis in a electrolyte supported SOEC.

  3. 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.

  4. 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.

  5. Quantifying cholesterol synthesis in vivo using 2H2O: enabling back-to-back studies in the same subject

    PubMed Central

    Previs, Stephen F.; Mahsut, Ablatt; Kulick, Alison; Dunn, Keiana; Andrews-Kelly, Genevieve; Johnson, Christopher; Bhat, Gowri; Herath, Kithsiri; Miller, Paul L.; Wang, Sheng-Ping; Azer, Karim; Xu, Jing; Johns, Douglas G.; Hubbard, Brian K.; Roddy, Thomas P.

    2011-01-01

    The advantages of using 2H2O to quantify cholesterol synthesis include i) homogeneous precursor labeling, ii) incorporation of 2H via multiple pathways, and iii) the ability to perform long-term studies in free-living subjects. However, there are two concerns. First, the t1/2 of tracer in body water presents a challenge when there is a need to acutely replicate measurements in the same subject. Second, assumptions are made regarding the number of hydrogens (n) that are incorporated during de novo synthesis. Our primary objective was to determine whether a step-based approach could be used to repeatedly study cholesterol synthesis a subject. We observed comparable changes in the 2H-labeling of plasma water and total plasma cholesterol in African-Green monkeys that received five oral doses of 2H2O, each dose separated by one week. Similar rates of cholesterol synthesis were estimated when comparing data in the group over the different weeks, but better reproducibility was observed when comparing replicate determinations of cholesterol synthesis in the same nonhuman primate during the respective dosing periods. Our secondary objective was to determine whether n depends on nutritional status in vivo; we observed n of ∼25 and ∼27 in mice fed a high-carbohydrate (HC) versus carbohydrate-free (CF) diet, respectively. We conclude that it is possible to acutely repeat studies of cholesterol synthesis using 2H2O and that n is relatively constant. PMID:21498887

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

    PubMed

    Wang, Xiao-Gang; Carrington, Tucker

    2015-07-14

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

  7. Theoretical study on structures and infrared spectroscopy of Cu2+(H2O)Ar n ( n = 1-4)

    NASA Astrophysics Data System (ADS)

    Song, Xiudan; Li, Shuxia; Jiang, Zishi; Zhang, Yongzhi

    2017-09-01

    The binding energy of Cu2+(H2O) is computed to be 98.4 kcal/mol and thus one-photon photodissociation is not possible in the 3400-3800 cm-1 (9.7-10.9 kcal/mol) region. To study whether the infrared photodissociation processes of Cu2+(H2O) can occur by multiple argon atoms tagging technique, density functional and CCSD(T) methods are used to investigate the geometries, OH stretching frequencies and the argon atom binding energies of Cu2+(H2O)Ar n ( n = 1-4) complexes. Various isomers are found resulting from the different coordination sites of argon atoms. The OH stretches in these complexes are shifted to lower frequencies than those of the free water molecule, and the corresponding vibrational red shifts are progressively smaller as more argon atom is added to Cu2+ while binding an argon atom to an OH site should lead to additional sizable red shift to the OH stretching vibrations.

  8. CO2/H2O adsorption equilibrium and rates on metal-organic frameworks: HKUST-1 and Ni/DOBDC.

    PubMed

    Liu, Jian; Wang, Yu; Benin, Annabelle I; Jakubczak, Paulina; Willis, Richard R; LeVan, M Douglas

    2010-09-07

    Metal-organic frameworks (MOFs) have recently attracted intense research interest because of their permanent porous structures, huge surface areas, and potential applications as novel adsorbents and catalysts. In order to provide a basis for consideration of MOFs for removal of carbon dioxide from gases containing water vapor, such as flue gas, we have studied adsorption equilibrium of CO(2), H(2)O vapor, and their mixtures and also rates of CO(2) adsorption in two MOFs: HKUST-1 (CuBTC) and Ni/DOBDC (CPO-27-Ni or Ni/MOF-74). The MOFs were synthesized via solvothermal methods, and the as-synthesized products were solvent exchanged and regenerated before experiments. Pure component adsorption equilibria and CO(2)/H(2)O binary adsorption equilibria were studied using a volumetric system. The effects of H(2)O adsorption on CO(2) adsorption for both MOF samples were determined, and the results for 5A and NaX zeolites were included for comparison. The hydrothermal stabilities for the two MOFs over the course of repetitive measurements of H(2)O and CO(2)/H(2)O mixture equilibria were also studied. CO(2) adsorption rates from helium for the MOF samples were investigated by using a unique concentration-swing frequency response (CSFR) system. Mass transfer into the MOFs is rapid with the controlling resistance found to be macropore diffusion, and rate parameters were established for the mechanism.

  9. 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

  10. 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.

  11. Predicting Phase Diagram of the CaCl2-H2O Binary System from the BET Adsorption Isotherm

    SciTech Connect

    Ally, Moonis Raza

    2008-01-01

    A recent publication in Fluid Phase Equilibria by Zeng (Zeng, Zhou et al. 2007) claimed remarkable accuracy in predicting the solubility of CaCl2-H2O solutions with the Brunaruer-Emett-Teller (BET) model parameters. Their approach necessarily requires prior knowledge of equilibrium water vapor pressures above saturated solutions as a function of temperature for the hydrates of CaCl2 that exist under those conditions. However, the intrinsic BET model does not require prior knowledge of such solubility data that the approach of (Zeng, Zhou et al. 2007) is dependent upon. This paper highlights the differences between the two approaches and covers a much wider range of compositions and temperatures than is done by (Zeng, Zhou et al. 2007). The statistical mechanical description of multilayer adsorption culminating in the BET adsorption isotherm for aqueous electrolytes as developed by Ally and Braunstein (Ally and Braunstein 1993) is used to predict the liquidus behavior of CaCl2-H2O across the entire composition range (from the melting point of pure water to the melting point of anhydrous calcium chloride), including possible metastable crystalline phases. The method requires as input the two BET parameters r, the statistically averaged number of adsorption sites and ε, the energy of adsorption of water in excess of the energy of condensation of pure water. Usually it suffices to keep r and ε constant, typically evaluated at 298.15 K, but in the case of CaCl2-H2O, it is found that both r and ε must be considered temperature dependent in order to predict the liquidus curve, eutectic and peritectic points with reasonable accuracy over the large temperature and compositional range for this binary system.

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

    NASA Astrophysics Data System (ADS)

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

    2000-12-01

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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. [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.

  19. Weather resistance of CaSO4 ṡ 1/2H2O-based sand-fixation material

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Tie, Shengnian

    2017-07-01

    Searching for an economical and effective sand-fixing material and technology is of great importance in Northwest China. This paper described the use of a semihydrated gypsum-(CaSO4 ṡ 1/2H2O-)based composite as a sand-fixing material. Its morphology and composition were characterized by SEM, and its water resistance, freezing-thawing resistance and wind erosion resistance were tested in the field. The results indicated that semihydrated gypsum-(CaSO4 ṡ 1/2H2O-)based sand-fixing composite has good water resistance and water-holding capacity. Its strength is maintained at 1.42 MPa after 50 freezing and thawing cycles, and its wind erosion increases with increasing wind speed and slope. Its compressive strength starts to decrease after nine months of field tests with no change in appearance, but it still satisfies the requirements of fixation technology. This sand-fixing material should have wide application owing to its good weather resistance.

  20. 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%).

  1. 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.

  2. 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.

  3. 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.

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

    PubMed

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

    2016-09-15

    Following administration of deuterated water ((2)H2O), the fractional synthetic rate (FSR) of a given endogenous protein can be estimated by (2)H-enrichment quantification of its alanine residues. Currently, this is measured by mass spectrometry following a derivatization procedure. Muscle FSR was measured by (1)H/(2)H NMR analysis of alanine from seabass kept for 6 days in 5% (2)H-enriched saltwater, following acid hydrolysis and amino acid isolation by cation-exchange chromatography of muscle tissue. The analysis is simple and robust, and provides precise measurements of excess alanine (2)H-enrichment in the 0.1-0.4% range from 50 mmol of alanine recovered from muscle protein. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Experimental Study on Dynamics of 2H2/O2/2Ar Detonations with a Constant Mass Divergence

    NASA Astrophysics Data System (ADS)

    Xiao, Qiang; Chang, Jiaxin; Fleche, Maxime La; Radulescu, Matei I.

    2016-11-01

    Very recently, Borzou and Radulescu (2016) formulated a novel solution allowing for an easy and precise quantification of loss effects during detonation propagation involving an exponentially shaped channel. They found that the detonation dynamics departed from the ZND model predictions, particularly for very unstable detonations. The question arises if the ZND model can predict the dynamics of much less unstable mixtures, in spite of the presence of a cellular structure. The present study focuses on a more stable mixture of 2H2/O2/2Ar with better known reaction kinetics. The results obtained experimentally for the velocity deficit in terms of the amount of mass divergence were found in excellent agreement with the predictions made with the ZND model, in spite of the detonation reaction zone being organized in strong cellular structures with reactive transverse waves.

  6. Non-Potassic Melts In CMAS-CO2-H2O-K2O Model Peridotite

    NASA Astrophysics Data System (ADS)

    Buisman, I.; Walter, M. J.; Keshav, S.

    2009-12-01

    Volatile mediated model systems have been fundamental in shaping our knowledge about the way we view melting phase relations of peridotite at various depths in the Earth. Volatiles not only affect the melting temperatures, but the resulting liquids are, in some case, dramatically different than those witnessed in melting of dry peridotite. For example, the influence of CO2 and H2O on the melting phase relations of model peridotite shows a remarkable decrease in the solidus temperatures when compared to the dry peridotite (Gudfinnsson and Presnall, 2005). These model systems illustrate a gradational change above the solidus from carbonatites to kimberlites over several hundreds of degrees. Group-II kimberlites are ultrapotassic rocks with high water content where the mineral phlogopite is abundant. To get a better understanding of the melting phase relations related to carbonatitic and kimberlitic magmas, K2O was added to the system CMAS-CO2-H2O. In these systems, fluid and melt can co-exist in P-T space. However, from past studies, it is also known that in hydrous systems, both the fluid and melt will become indistinguishable from one another creating a singularity (second critical endpoint). Starting from the solidus located in six components (Keshav and Gudfinnsson, AGU abstract, 2009), with seven phases, melting phase relations in CMAS-CO2-H2O-K2O involving, fo-opx-cpx-garnet-carbonate-melt-fluid, are divariant. Fluid was recognized with the observation of large cavities seen in exposed capsules. Moreover, the presence of bright, needle-like grains found in large cavities in backscattered images implies the presence of solute in the fluid phase. Significantly, liquids on this divariant region have about 1000 ppm K2O, and so is the case with accompanying cpx. Hence, with this non-interesting amount of K2O in the mentioned phases, fluid must have all the potassium. At 30 kbar/1100C, with fo-opx-cpx-garnet-carbonate-phlogopite-melt-fluid, the melting phase

  7. 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.

  8. 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.

  9. A vibrational spectroscopic study of the phosphate mineral churchite (REE)(PO(4))⋅2H(2)O.

    PubMed

    Frost, Ray L; López, Andrés; Scholz, Ricardo; Xi, Yunfei; Filho, Mauro Cândido

    2014-06-05

    Vibrational spectroscopy has been used to study the rare earth mineral churchite of formula (REE)(PO4)⋅2H2O. The mineral contains a range of rare earth metals including yttrium depending on the locality. The Raman spectra of churchite-(REE) are characterized by an intense sharp band at 984cm(-1) assigned to the ν1(PO4(3-)) symmetric stretching mode. A lower intensity band observed at around 1067cm(-1) is attributed to the ν3(PO4(3-)) antisymmetric stretching mode. The (PO4(3-)) bending modes are observed at 497cm(-1) (ν2) and 565cm(-1)(ν4). Raman bands at 649 and 681cm(-1) are assigned to water librational modes. Vibrational spectroscopy enables aspects of the structure of churchite to be ascertained. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. 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.

  11. Production of graphene quantum dots by ultrasound-assisted exfoliation in supercritical CO2/H2O medium.

    PubMed

    Gao, Hanyang; Xue, Chen; Hu, Guoxin; Zhu, Kunxu

    2017-07-01

    In this research, three kinds of graphene quantum dots (GQDs)-pristine graphene quantum dots (PGQDs), expanded graphene quantum dots (EGQDs) and graphene oxide quantum dots (GOQDs)-were produced from natural graphite, expanded graphite, and oxide graphite respectively in an ultrasound-assisted supercritical CO2 (scCO2)/H2O system. The effects of aqueous solution content ratio, system pressure, and ultrasonic power on the yields of different kinds of GQDs were investigated. According to these experiment results, the combination of the intense knocking force generated from high-pressure acoustic cavitation in a scCO2/H2O system and the superior penetration ability of scCO2 was considered to be the key to the successful exfoliation of such tiny pieces from bulk graphite. An interesting result was found that, contrary to common experience, the yield of PGQDs from natural graphite was much higher than that of GOQDs from graphite oxide. Based on the experimental analysis, the larger interlayer resistance of natural graphite, which hindered the insertion of scCO2 molecules, and the hydrophobic property of natural graphite surface, which made the planar more susceptible to the attack of ultrasonic collapsing bubbles, were deduced to be the two main reasons for this result. The differences in characteristics among the three kinds of GQDs were also studied and compared in this research. In our opinion, this low-cost and time-saving method may provide an alternative green route for the production of various kinds of GQDs, especially PGQDs. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Synthesis of Nanoscale CaO-Al2O3-SiO2-H2O and Na2O-Al2O3-SiO2-H2O Using the Hydrothermal Method and Their Characterization

    PubMed Central

    Yang, Jingbin; Li, Dongxu; Fang, Yuan

    2017-01-01

    C-A-S-H (CaO-Al2O3-SiO2-H2O) and N-A-S-H (Na2O-Al2O3-SiO2-H2O) have a wide range of chemical compositions and structures and are difficult to separate from alkali-activated materials. Therefore, it is difficult to analyze their microscopic properties directly. This paper reports research on the synthesis of C-A-S-H and N-A-S-H particles with an average particle size smaller than 300 nm by applying the hydrothermal method. The composition and microstructure of the products with different CaO(Na2O)/SiO2 ratios and curing conditions were characterized using XRD, the RIR method, FTIR, SEM, TEM, and laser particle size analysis. The results showed that the C-A-S-H system products with a low CaO/SiO2 ratio were mainly amorphous C-A-S-H gels. With an increase in the CaO/SiO2 ratio, an excess of Ca(OH)2 was observed at room temperature, while in a high-temperature reaction system, katoite, C4AcH11, and other crystallized products were observed. The katoite content was related to the curing temperature and the content of Ca(OH)2 and it tended to form at a high-temperature and high-calcium environment, and an increase in the temperature renders the C-A-S-H gels more compact. The main products of the N-A-S-H system at room temperature were amorphous N-A-S-H gels and a small amount of sodalite. An increase in the curing temperature promoted the formation of the crystalline products faujasite and zeolite-P. The crystallization products consisted of only zeolite-P in the high-temperature N-A-S-H system and its content were stable above 70%. An increase in the Na2O/SiO2 ratio resulted in more non-bridging oxygen and the TO4 was more isolated in the N-A-S-H structure. The composition and microstructure of the C-A-S-H and N-A-S-H system products synthesized by the hydrothermal method were closely related to the ratio of the raw materials and the curing conditions. The results of this study increase our understanding of the hydration products of alkali-activated materials. PMID

  17. 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).

  18. 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

  19. [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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Plasma Proteome Dynamics: Analysis of Lipoproteins and Acute Phase Response Proteins with 2H2O Metabolic Labeling*

    PubMed Central

    Li, Ling; Willard, Belinda; Rachdaoui, Nadia; Kirwan, John P.; Sadygov, Rovshan G.; Stanley, William C.; Previs, Stephen; McCullough, Arthur J.; Kasumov, Takhar

    2012-01-01

    Understanding the pathologies related to the regulation of protein metabolism requires methods for studying the kinetics of individual proteins. We developed a 2H2O metabolic labeling technique and software for protein kinetic studies in free living organisms. This approach for proteome dynamic studies requires the measurement of total body water enrichments by GC-MS, isotopic distribution of the tryptic peptide by LC-MS/MS, and estimation of the asymptotical number of deuterium incorporated into a peptide by software. We applied this technique to measure the synthesis rates of several plasma lipoproteins and acute phase response proteins in rats. Samples were collected at different time points, and proteins were separated by a gradient gel electrophoresis. 2H labeling of tryptic peptides was analyzed by ion trap tandem mass spectrometry (LTQ MS/MS) for measurement of the fractional synthesis rates of plasma proteins. The high sensitivity of LTQ MS in zoom scan mode in combination with 2H label amplification in proteolytic peptides allows detection of the changes in plasma protein synthesis related to animal nutritional status. Our results demonstrate that fasting has divergent effects on the rate of synthesis of plasma proteins, increasing synthesis of ApoB 100 but decreasing formation of albumin and fibrinogen. We conclude that this technique can effectively measure the synthesis of plasma proteins and can be used to study the regulation of protein homeostasis under physiological and pathological conditions. PMID:22393261

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  6. Molecular simulation of CH4/CO2/H2O competitive adsorption on low rank coal vitrinite.

    PubMed

    Yu, Song; Bo, Jiang; Wu, Li

    2017-07-21

    The competitive adsorptions of CH4/CO2/H2O on coal vitrinite (DV-8, C214H180O24N2) were computed based on density function theory (DFT) and grand canonical Monte Carlo (GCMC). The adsorption process reaches the saturation state after adsorbing 17 CH4s, 22 CO2s, and 35 H2Os per C214H180O24N2 respectively. The optimal configurations of CH4-vitrinite, CO2-vitrinite, and H2O-vitrinite respectively manifest as aromatic(1)/T(2)/rT(3) (1 adsorption location, 2 adsorption sites and T here represents sites above the carbon atom and the heteroatom, 3 adsorption orientation and rT here means the orientations of three hydrogen atoms pointing to vitrinite), aromatic/T/v (v represents the orientations perpendicular to the plane of vitrinite), and aromatic/rV/T (rV represents an oxygen atom pointing to the vitrinite surface). The GCMC results show that high temperature is not conducive to the vitrinite's adsorption of adsorbates and the adsorption capacity order is H2O > CO2 > CH4 (263-363 K) in the one-component, binary, and ternary adsorbate systems. The optimal configurations of vitrinite are similar to graphite/graphene, while ΔE is significantly lower than graphite/graphene. Simulation data are in good agreement with the experimental results.

  7. Electron paramagnetic resonance of [(CH3)3NH]CuCl3.2H2O

    NASA Astrophysics Data System (ADS)

    Ritter, Mark B.; Drumheller, John E.; Kite, Terence M.; Snively, Leslie O.; Emerson, Kenneth

    1983-11-01

    The electron paramagnetic resonance of [(CH3)3NH]CuCl3.2H2O has been studied in the temperature range of 4 K to room temperature. This compound is known to behave magnetically as a spin- 1/2 , one-dimensional Heisenberg ferromagnetic with ordering below 1K. In the high-temperature regime the EPR data show a rich angular dependence of the linewidths as the magnetic field is rotated away from the chain. The data were analyzed in manner similar to that used by McGregor and Soos, who used the Blume-Hubbard result for spin dynamics and extracted exchange anisotropies in one dimension. For adequate fit, we reduced the symmetry of symmetric anisotropic exchange to orthorhombic and included the antisymmetric exchange. Isotropic symmetric, dipolar, anisotropic symmetric, and antisymmetric exchange therefore were included with the room temperature results of J0=0.8 K, Dd=0.058 K, De=0.032 K, and d=0.043 K, respectively, and further show about a 12% XY character to the exchange. These results are reasonably consistent with the previous results on this compound. Splitting of the EPR lines indicate that there are two inequivalent chains along the needle axis. Data to 4 K indicate no significant changes in the angle dependence but an anomalous monotonic broadening of the linewidths is observed as temperature is lowered.

  8. 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.

  9. 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!!!

  10. 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!

  11. 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.

  12. 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.

  13. 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.

  14. Use of 2H2O for estimating rates of gluconeogenesis: determination and correction of error due to transaldolase exchange

    PubMed Central

    Burgess, Shawn C.

    2012-01-01

    The use of deuterated water as a method to measure gluconeogenesis has previously been well validated and is reflective of normal human physiology. However, there has been concern since the method was first introduced that transaldolase exchange may lead to the overestimation of gluconeogenesis. We examined the impact of transaldolase exchange on the estimation of gluconenogenesis using the deuterated water method under a variety of physiological conditions in humans by using the gluconeogenic tracer [U-13C]propionate, 2H2O, and 2H/13C nuclear magnetic resonance (NMR) spectroscopy. When [U-13C]propionate was used, 13C labeling inequality occurred between the top and bottom halves of glucose in individuals fasted for 12–24 h who were weight stable (n = 18) or had lost weight via calorie restriction (n = 7), consistent with transaldolase exchange. Similar analysis of glucose standards revealed no significant difference in the total 13C enrichment between the top and bottom halves of glucose, indicating that the differences detected were biological, not analytical, in origin. This labeling inequality was attenuated by extending the fasting period to 48 h (n = 12) as well as by dietary carbohydrate restriction (n = 7), both conditions associated with decreased glycogenolysis. These findings were consistent with a transaldolase effect; however, the resultant overestimation of gluconeogenesis in the overnight-fasted state was modest (7–12%), leading to an error of 14–24% that was easily correctable by using either a simultaneous 13C gluconeogenic tracer or a correction nomogram generated from data in the present study. PMID:23032685

  15. 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)

  16. 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.

  17. 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.

  18. Detonation re-initiation in a concentric tube arrangement for C_2H_2/O_2/Ar mixtures

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    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_2H_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.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  2. 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.

  3. Growth and shape control of orthorhombic Fe 5(PO 4) 4(OH) 3·2H 2O single crystalline dendrites

    NASA Astrophysics Data System (ADS)

    Li, Guicun; Zhang, Shuai; Peng, Hongrui; Chen, Kezheng

    2010-10-01

    Orthorhombic Fe 5(PO 4) 4(OH) 3·2H 2O single crystalline dendritic nanostructures have been synthesized by a facile and reproducible hydrothermal method without the aid of any surfactants. The influences of synthetic parameters, such as reaction time, temperature, the amount of H 2O 2 solution, pH values, and types of iron precursors, on the crystal structures and morphologies of the resulting products have been investigated. The formation process of Fe 5(PO 4) 4(OH) 3·2H 2O dendritic nanostructures is time dependent: amorphous FePO 4· nH 2O nanoparticles are formed firstly, and then Fe 5(PO 4) 4(OH) 3·2H 2O dendrites are assembled via a crystallization-orientation attachment process, accompanying a color change from yellow to green. The shapes and sizes of Fe 5(PO 4) 4(OH) 3·2H 2O products can be controlled by adjusting the amount of H 2O 2 solution, pH values, and types of iron precursors in the reaction system.

  4. DFT studies of copper(II) complexes of cis-1,2-diaminocyclohexane (Dach) and crystal structure of [Cu(Dach)2(H2O)]Cl2

    NASA Astrophysics Data System (ADS)

    Nawaz, Sidra; Ghaffar, Abdul; Zierkiewicz, Wiktor; Monim-ul-Mehboob, Muhammad; Khurram; Tahir, Muhammad Nawaz; Isab, Anvarhusein A.; Ahmad, Saeed

    2017-06-01

    A copper(II) complex, [Cu(Dach)2(H2O)]Cl2 (1) (Dach = cis-1,2-Diaminocyclohexane) has been prepared and characterized by IR spectroscopy and X-ray crystallography. The crystal structure of complex 1 is ionic consisting of [Cu(Dach)2(H2O)]2+ cation and two chloride counter ions. The copper atom in the complex ion assumes a distorted square pyramidal geometry with water occupying the apical position. The adjacent molecules are joined by hydrogen bonding to form irregular chains. The structures of [Cu(Dach)2(H2O)]Cl2 (1) and three of its analogues, [Cu(Dach)2Cl]Cl·H2O (2), [Cu(Dach)2(H2O)Cl]Cl (3) and [Cu(Dach)2Cl2]·H2O (4) were predicted by DFT calculations. The DFT results reveal that in the gas phase, the structure 1 is less stable in comparison to the calculated structure, [Cu(Dach)2Cl2]·H2O (4). The additional calculations were performed for the complexes investigated in solution (water) using the polarizable continuum model. According to these calculations, the electronic energies (stabilities) of the complexes 1 and 4 in the solvent are comparable to each other. The atomic charges and second-order interaction energies between orbitals for complexes 1-4 were calculated with natural bond orbital (NBO) analysis.

  5. 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

  6. 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

  7. Hydrothermal synthesis and crystal structure of Cs 6[(UO 2) 4(W 5O 21)(OH) 2(H 2O) 2]: a new polar uranyl tungstate

    NASA Astrophysics Data System (ADS)

    Sykora, Richard E.; Albrecht-Schmitt, Thomas E.

    2004-10-01

    The hydrothermal reaction of UO3, WO3, and CsIO4 leads to the formation of Cs6[(UO2)4(W5O21)(OH)2(H2O)2] and UO2(IO3)2(H2O). Cs6[(UO2)4(W5O21)(OH)2(H2O)2] is the first example of a hydrothermally synthesized uranyl tungstate. It's structure has been determined by single-crystal X-ray diffraction. Crystallographic data: tetragonal, space group I4 cm, a = 15.959 (2) Å , c = 14.215 (1) Å , Z = 4 , Mo Kα , λ = 0.71073 Å , R (F) = 2.84 % for 135 parameters with 2300 reflections with I > 2 σ (I) . The structure is comprised of two-dimensional ∞2[(UO2)4(W5O21) (OH)2(H2O)2]6- anionic layers that are separated by Cs+ cations. The coordination polyhedra found in the novel layers consist of UO7 pentagonal bipyramids, WO6 distorted octahedra, and WO5 square pyramids. The UO7 polyhedra are formed from the binding of five equatorial oxygen atoms around a central uranyl, UO22+, unit. Both bridging and terminal oxo ligands are employed in forming the WO5 square pyramidal units, while oxo, hydroxo, and aqua ligands are found in the WO6 distorted octahedra. In the layers, four (UO2)O5 polyhedra corner share with equatorial oxygen atoms to form a U4O24 tetramer entity with a square site in the center; a tungsten atom populates the center of each of these sites to form a U4WO25 pentamer unit. The pentamer units that result are connected in two dimensions by edge-shared dimers of WO6 octahedra to form the two-dimensional ∞ 2 [(UO2)4(W5O21)(OH)2(H2O)2]6- layers. The lack of inversion symmetry in Cs6[(UO2)4(W5O21)(OH)2(H2O)2] can be directly contributed to the WO5 square pyramids found in the pentamer units. In the structure, all of these polar polyhedra align their terminal oxygens in the same orientation, along the c axis, thus resulting in a polar compound.

  8. Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl2·2H2O/CaCl2

    PubMed Central

    Xu, Xiaoxiao; Dong, Zhijun; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi

    2017-01-01

    Salt hydrates have issues of supercooling when they are utilized as phase change materials (PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM system to reduce the supercooling phenomenon existing in CaCl2·6H2O. Six samples with different compositions of CaCl2 were prepared. The relationship between the performance and the proportion of calcium chloride dihydrate (CaCl2·2H2O) and calcium chloride anhydrous (CaCl2) was also investigated. The supercooling degree of the final PCM reduced with the increase in volume of CaCl2·2H2O during its preparation. The PCM obtained with 66.21 wt % CaCl2·2H2O reduced the supercooling degree by about 96.8%. All six samples, whose ratio of CaCl2·2H2O to (CaCl2 plus CaCl2·2H2O) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings for thermal energy storage purposes. Hence, CaCl2·2H2O plays an important role in reducing supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of adding different percentages of Nano-SiO2 (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling degree of some PCM samples was investigated. The test results showed that the supercooling of the salt hydrate PCM in Samples 6 and 5 reduced to 0.2 °C and 0.4 °C respectively. Finally, the effect of the different cooling conditions, including frozen storage (−20 °C) and cold storage (5 °C), that were used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of the two materials, the performance and properties of the newly developed PCM systems were better especially in terms of reducing the supercooling degree of the PCM

  9. K2M(H2P2O7)2.2H2O (M = Ni, Cu, Zn): orthorhombic forms and Raman spectra.

    PubMed

    Essehli, Rachid; El Bali, Brahim; Alaoui Tahiri, Aziz; Lachkar, Mohammed; Manoun, Bouchaib; Dusek, Michal; Fejfarova, Karla

    2005-12-01

    The crystal structures of three isotypic orthorhombic dihydrogendiphosphates, namely dipotassium copper(II)/nickel(II)/zinc(II) bis(dihydrogendiphosphate) dihydrate, K2M(H2P2O7)2.2H2O (M = Cu, Ni and Zn), have been refined from single-crystal data. The M2+ and K+ cations are located at sites of m symmetry, and the P atoms occupy general positions. These compounds also exist in triclinic forms with very similar structural features. The structures of both forms are compared, as well as the geometry of the MO6 octahedron, which is considerably elongated towards the water molecules for M = Ni and Cu. Such elongation has not been observed among the other representatives of the family. A Raman study of the whole series K2M(H2P2O7)2.2H2O (M = Mn, Co, Ni, Cu, Zn and Mg) is reported.

  10. 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.

  11. 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.

  12. Hysteresis effect of ammonium and water protons by 1H MAS NMR in (NH4)2CuBr4·2H2O

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran; Cho, Jiung

    2017-10-01

    The chemical shifts, linewidths, and spin-lattice relaxation times for ammonium and water protons in (NH4)2CuBr4·2H2O were investigated by 1H magic angle spinning nuclear magnetic resonance (MAS NMR) with a focus on the roles of NH4+ and H2O at high temperatures. The changes in the temperature dependence of the data near Td (=360 K) were related to variations of the H environments; the mechanism above Td was related to hydrogen-bond transfer involving breakage of the weak part of the hydrogen bond. The hysteresis effects for the ammonium and water protons in (NH4)2CuBr4·2H2O by MAS NMR were described with respect to heating and cooling.

  13. Tetrahedral Networks Containing Beryllium: Syntheses and Structures of Be 3(PO 4) 2 · 2H 2O and Be(HAsO 4) · H 2O

    NASA Astrophysics Data System (ADS)

    Gier, Thurman E.; Bu, Xianhui; Stucky, Galen D.; Harrison, William T. A.

    1999-09-01

    The hydrothermal syntheses and single crystal structures of Be3(PO4)2 · 2H2O and Be(HAsO4) · H2O are described. These phases are built up from vertex-sharing tetrahedra, but their overall structures are quite different. In Be3(PO4)2 · 2H2O, BeO4, BeO2(H2O)2, and PO4 groups build up a three-dimensional structure via Be-O-P and Be-O-Be bonds, resulting in tetrahedral 3- and 4-rings. Be(HAsO4) · H2O is layered and contains 6-rings of BeO3(H2O) and HAsO4 building blocks fused via Be-O-As bonds. Similarities and differences to some other tetrahedral structures are discussed. Crystal data: Be3(PO4)2 · 2H2O, Mr=253.01, monoclinic, space group C2/c (No. 15), a=15.9640 (6) Å, b=4.5842(2) Å, c=9.5320(4) Å, β=94.366(2)°, V=695.6(2) Å3, Z=4, R(F)=3.79%, Rw(F)=4.44% [812 reflections with I>2σ(I)]. Be(HAsO4) · H2O, Mr=166.95, orthorhombic, space group Pca21 (No. 29), a=9.7471(2) Å, b=4.6794(1) Å, c=8.5929(1) Å, V=391.93(9) Å3, Z=4, R(F)=3.93%, Rw(F)=4.32% [795 reflections with I>2σ(I)].

  14. 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.

  15. 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)

  16. 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)

  17. 2H2O-based high-density lipoprotein turnover method for the assessment of dynamic high-density lipoprotein function in mice.

    PubMed

    Kasumov, Takhar; Willard, Belinda; Li, Ling; Li, Min; Conger, Heather; Buffa, Jennifer A; Previs, Stephen; McCullough, Arthur; Hazen, Stanley L; Smith, Jonathan D

    2013-08-01

    High-density lipoprotein (HDL) promotes reverse cholesterol transport from peripheral tissues to the liver for clearance. Reduced HDL-cholesterol (HDLc) is associated with atherosclerosis; however, as a predictor of cardiovascular disease, HDLc has limitations because it is not a direct marker of HDL functionality. Our objective was to develop a mass spectrometry-based method for the simultaneous measurement of HDLc and ApoAI kinetics in mice, using a single (2)H2O tracer, and use it to examine genetic and drug perturbations on HDL turnover in vivo. Mice were given (2)H2O in the drinking water, and serial blood samples were collected at different time points. HDLc and ApoAI gradually incorporated (2)H, allowing experimental measurement of fractional catabolic rates and production rates for HDLc and ApoAI. ApoE(-/-) mice displayed increased fractional catabolic rates (P<0.01) and reduced production rates of both HDLc and ApoAI (P<0.05) compared with controls. In human ApoAI transgenic mice, levels and production rates of HDLc and human ApoAI were strikingly higher than in wild-type mice. Myriocin, an inhibitor of sphingolipid synthesis, significantly increased both HDL flux and macrophage-to-feces reverse cholesterol transport, indicating compatibility of this HDL turnover method with the macrophage-specific reverse cholesterol transport assay. (2)H2O-labeling can be used to measure HDLc and ApoAI flux in vivo, and to assess the role of genetic and pharmacological interventions on HDL turnover in mice. Safety, simplicity, and low cost of the (2)H2O-based HDL turnover approach suggest that this assay can be scaled for human use to study effects of HDL targeted therapies on dynamic HDL function.

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

    PubMed Central

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

    2013-01-01

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

  19. 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.

  20. 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

  1. 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.

  2. A Raman spectroscopic study of the basic carbonate mineral callaghanite Cu2Mg2(CO3)(OH)6·2H2O.

    PubMed

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

    2013-05-01

    Raman spectrum of callaghanite, Cu2Mg2(CO3)(OH)6·2H2O, was studied and compared with published Raman spectra of azurite, malachite and hydromagnesite. Stretching and bending vibrations of carbonate and hydroxyl units and water molecules were tentatively assigned. Approximate O-H…O hydrogen bond lengths were inferred from the spectra. Because of the high content of hydroxyl ions in the crystal structure in comparison with low content of carbonate units, callaghanite should be better classified as a carbonatohydroxide than a hydroxycarbonate. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  5. Latent porosity in potassium dodecafluoro-closo-dodecaborate(2-). Structures and rapid room temperature interconversions of crystalline K2B12F12, K2(H2O)2B12F12, and K2(H2O)4B12F12 in the presence of water vapor.

    PubMed

    Peryshkov, Dmitry V; Popov, Alexey A; Strauss, Steven H

    2010-10-06

    Structures of K(2)(H(2)O)(2)B(12)F(12) and K(2)(H(2)O)(4)B(12)F(12) were determined by X-ray diffraction. They contain [K(μ-H(2)O)(2)K](2+) and [(H(2)O)K(μ-H(2)O)(2)K(H(2)O)](2+) dimers, respectively, which interact with superweak B(12)F(12)(2-) anions via multiple K···F(B) interactions and (O)H···F(B) hydrogen bonds (the dimers in K(2)(H(2)O)(4)B(12)F(12) are also linked by (O)H···O hydrogen bonds). DFT calculations show that both dimers are thermodynamically stabilized by the lattice of anions: the predicted ΔE values for the gas-phase dimerization of two K(H(2)O)(+) or K(H(2)O)(2)(+) cations into [K(μ-H(2)O)(2)K](2+) or [(H(2)O)K(μ-H(2)O)(2)K(H(2)O)](2+) are +232 and +205 kJ mol(-1), respectively. The calculations also predict that ΔE for the gas-phase reaction 2 K(+) + 2 H(2)O → [K(μ-H(2)O)(2)K](2+) is +81.0 kJ mol, whereas ΔH for the reversible reaction K(2)B(12)F(12 (s)) + 2 H(2)O((g)) → K(2)(H(2)O)(2)B(12)F(12 (s)) was found to be -111 kJ mol(-1) by differential scanning calorimetry. The K(2)(H(2)O)(0,2,4)B(12)F(12) system is unusual in how rapidly the three crystalline phases (the K(2)B(12)F(12) structure was reported recently) are interconverted, two of them reversibly. Isothermal gravimetric and DSC measurements showed that the reaction K(2)B(12)F(12 (s)) + 2 H(2)O((g)) → K(2)(H(2)O)(2)B(12)F(12 (s)) was complete in as little as 4 min at 25 °C when the sample was exposed to a stream of He or N(2) containing 21 Torr H(2)O((g)). The endothermic reverse reaction required as little as 18 min when K(2)(H(2)O)(2)B(12)F(12) at 25 °C was exposed to a stream of dry He. The products of hydration and dehydration were shown to be crystalline K(2)(H(2)O)(2)B(12)F(12) and K(2)B(12)F(12), respectively, by PXRD, and therefore these reactions are reconstructive solid-state reactions (there is also evidence that they may be single-crystal-to-single-crystal transformations when carried out very slowly). The hydration and dehydration reaction

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Effect of ultrasound on the morphology of the CaCO3 precipitated from CaSO4-NH3-CO2-H2O system

    NASA Astrophysics Data System (ADS)

    Cheng, Huaigang; Wang, Xin; Wang, Bo; Zhao, Jing; Liu, Yong; Cheng, Fangqin

    2017-07-01

    Micron-grade calcium carbonate (CaCO3) crystals are by-products in the preparation of (NH4)2SO4 fertilizer using CaSO4·2H2O, NH3, and CO2. Since ultrasound can make crystals smaller and their morphology quite complex, the morphological change rules need to be studied to make meaningful use of them. In the present work, the morphologies of CaCO3 crystals precipitated from the ultrasound CaSO4-NH3-CO2-H2O system were analyzed in different conditions. It was found that ultrasound can make the crystals smaller in nucleation or the early growth stage, or it can make the shapes diversified and dispersed by influencing the solution property and in the aging process. In an ultrasound environment, crystals may be square, spheroidal, ellipsoidal, pisciform (spindle), hexagonal, carambola-like, or scattered particles. High-concentrations of NH3 and CO2 facilitate CaCO3 crystals becoming smooth balls, while high-intensity ultrasound and a high-concentration of foreign Na+ ions help to turn CaCO3 into tiny square particles or a clustered aggregate of tiny particles with rough surfaces.

  11. Mechanistic Studies of Wacker-Type Amidocyclization of Alkenes Catalyzed by (IMes)Pd(TFA)2(H2O): Kinetic and Stereochemical Implications of Proton Transfer†

    PubMed Central

    Ye, Xuan; White, Paul B.

    2012-01-01

    The stereochemical course of the amidopalladation of alkenes has important implications for the development of enantioselective Pd-catalyzed “Wacker-type” oxidative amination of alkenes. We have recently shown that the addition of base (Na2CO3) can alter the stereochemical course of amidopalladation in the (IMes)Pd(TFA)2(H2O)-catalyzed aerobic oxidative amidation of alkene. In this study, the mechanism of (IMes)Pd(TFA)2(H2O)-catalyzed oxidative heterocyclization of (Z)-4-hexenyltosylamide was investigated in the presence and absence of exogenous base Na2CO3. The results reveal two parallel pathways in the absence of base: a cis-amidopalladation pathway with turnover-limiting deprotonation of the sulfonamide nucleophile, and a trans-amidopalladation pathway with turnover-limiting nucleophilic attack of sulfonamide on the coordinated alkene. The addition of base (Na2CO3) lowers the energy barrier associated with the proton transfer, leading to an overall faster turnover rate and exclusive cis-amidopalladation of alkene. PMID:23157332

  12. Mechanistic studies of Wacker-type amidocyclization of alkenes catalyzed by (IMes)Pd(TFA)2(H2O): kinetic and stereochemical implications of proton transfer.

    PubMed

    Ye, Xuan; White, Paul B; Stahl, Shannon S

    2013-03-01

    The stereochemical course of the amidopalladation of alkenes has important implications for the development of enantioselective Pd-catalyzed "Wacker-type" oxidative amidation of alkenes. We have recently shown that the addition of base (Na2CO3) can alter the stereochemical course of amidopalladation in the (IMes)Pd(TFA)2(H2O)-catalyzed aerobic oxidative amidation of alkene. In this study, the mechanism of (IMes)Pd(TFA)2(H2O)-catalyzed oxidative heterocyclization of (Z)-4-hexenyltosylamide was investigated in the presence and absence of exogenous base Na2CO3. The results reveal two parallel pathways in the absence of base: a cis-amidopalladation pathway with turnover-limiting deprotonation of the sulfonamide nucleophile and a trans-amidopalladation pathway with turnover-limiting nucleophilic attack of sulfonamide on the coordinated alkene. The addition of base (Na2CO3) lowers the energy barrier associated with the proton transfer, leading to an overall faster turnover rate and exclusive cis-amidopalladation of alkene.

  13. 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.

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

    PubMed

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

    2016-06-20

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

  15. 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.

  16. 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.

  17. 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.

  18. Redox-induced solid-solid phase transformation of TCNQ microcrystals into semiconducting Ni[TCNQ]2(H2O)2 nanowire (flowerlike) architectures: a combined voltammetric, spectroscopic, and microscopic study.

    PubMed

    Nafady, Ayman; Bond, Alan M

    2007-05-14

    The facile solid-solid phase transformation of TCNQ microcrystals into semiconducting and magnetic Ni[TCNQ]2(H2O)2 nanowire (flowerlike) architectures is achieved by reduction of TCNQ-modified electrodes in the presence of Ni2+(aq)-containing electrolytes. Voltammetric probing revealed that the chemically reversible TCNQ/Ni[TCNQ]2(H2O)2 conversion process is essentially independent of electrode material and the identity of nickel counteranion but is significantly dependent on scan rate, Ni2+(aq) electrolyte concentration, and the method of solid TCNQ immobilization (drop casting or mechanical attachment). Data analyzed from cyclic voltammetric and double-potential step chronoamperometric experiments are consistent with formation of the Ni[TCNQ]2(H2O)2 complex via a rate-determining nucleation/growth process that involves incorporation of Ni2+(aq) ions into the reduced TCNQ crystal lattice at the triple phase TCNQ|electrode|electrolyte interface. The reoxidation process, which includes the conversion of solid Ni[TCNQ]2(H2O)2 back to TCNQ0 crystals, is also controlled by nucleation/growth kinetics. The overall redox process associated with this chemically reversible solid-solid transformation, therefore, is described by the equation: TCNQ0(S) + 2e- + Ni2+(aq)+ 2 H2O <==> {Ni[TCNQ]2(H2O)2}(S). SEM monitoring of the changes that accompany the TCNQ/Ni[TCNQ]2(H2O)2 transformation revealed that the morphology and crystal size of electrochemically generated Ni[TCNQ]2(H2O)2 are substantially different from those of parent TCNQ crystals. Importantly, the morphology of Ni[TCNQ]2(H2O)2 can be selectively manipulated to produce either 1-D/2-D nanowires or 3-D flowerlike architectures via careful control over the experimental parameters used to accomplish the solid-solid phase interconversion process.

  19. 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.

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

    PubMed

    Mirwald, P W

    2005-09-22

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

  1. Polyoxometal cations within polyoxometalate anions. Seven-coordinate uranium and zirconium heteroatom groups in [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14-

    NASA Astrophysics Data System (ADS)

    Gaunt, Andrew J.; May, Iain; Collison, David; Travis Holman, K.; Pope, Michael T.

    2003-08-01

    Two new composite polyoxotungstate anions with unprecedented structural features, [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- (1) and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14- (2) contain polyoxo-uranium and -zirconium clusters as bridging units. The anions are synthesized by reaction of Na12[P2W15O56] with solutions of UO2(NO3)2 and ZrCl4. The structure of 1 in the sodium salt contains four [P2W15O56]12- anions assembled into an overall tetrahedral cluster by means of trigonal bridging groups formed by three equatorial-edge-shared UO7 pentagonal bipyramids. The structure of anion 2 consists of a centrosymmetric assembly of two [P2W16O59]12- anions linked by a {Zr4O2(OH)2(H2O)4}10+ cluster. Both complexes in solution yield the expected two-line 31P-NMR spectra with chemical shifts of -2.95, -13.58 and -6.45, -13.69 ppm, respectively.

  2. 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.

  3. The structural transformation of monoclinic [(R)-C5H14N2][Cu(SO4)2(H2O)4].2H2O into orthorhombic [(R)-C5H14N2]2[Cu(H2O)6](SO4)3: crystal structures and thermal behavior

    NASA Astrophysics Data System (ADS)

    Saïd, Salem; Mhadhbi, Noureddine; Hajlaoui, Fadhel; Yahyaoui, Samia; Norquist, Alexander J.; Mhiri, Tahar; Bataille, Thierry; Naïli, Houcine

    2014-01-01

    Single crystals of [(R)-C5H14N2][Cu(SO4)2(H2O)4].2H2O (1) were grown through the slow evaporation of a solution containing H2SO4, (R)-C5H12N2 and CuSO4.5H2O. These crystals spontaneously transform to [(R)-C5H14N2]2[Cu(H2O)6](SO4)3 (2) over the course of four days at room temperature. The same single crystal on the same mounting was used for the determination of the structure of (1) and the unit cell determination of (2). A second single crystal of the transformed batch has served for the structural determination of (2). Compound 1 crystallizes in the noncentrosymmetric space group P21 (No. 4) and consists of trimeric [Cu(SO4)2(H2O)4]2- anions, [(R)-C5H14N2]2+ cations and occluded water molecules. Compound 2 crystallizes in P21212 (No. 18) and contains [Cu(H2O)6]2+ cations, [SO4]2- anions and occluded water molecules. The thermal decompositions of compounds 1 and 2 were studied by thermogravimetric analyses and temperature-dependent X-ray diffraction.

  4. Coexistence of cyclic (CH3OH)2(H2O)8 heterodecamer and acyclic water trimer in the channels of silver-azelate framework

    NASA Astrophysics Data System (ADS)

    Luo, Geng-Geng; Zhu, Rui-Min; He, Wei-Jun; Li, Ming-Zhi; Zhao, Qing-Hua; Li, Dong-Xu; Dai, Jing-Cao

    2012-08-01

    Flexible azelaic acid (H2aze) and 1,3-bis(4-pyridyl)propane) (bpp) react ultrasonically with silver(I) oxide, generating a new metal-organic framework [Ag2(bpp)2(aze)·7H2O·CH3OH]n (1) that forms a 3D supramolecular structure through H-bonding interactions between solvent molecules and carboxylate O atoms with void spaces. Two kinds of solvent clusters, discrete cyclic (CH3OH)2(H2O)8 heterodecameric and acyclic water trimeric clusters occupy the channels in the structure. Furthermore, 1 exhibits strong photoluminescence maximized at 500 nm upon 350 nm excitation at room temperature, of which CIE chromaticity ordinate (x = 0.28, y = 0.44) is close to that of edge of green component.

  5. 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.

  6. 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.

  7. Anomalous dielectric response of short hydrogen bonds under pressure: the case of (Mn,Fe)2+AlPO4(OH)2H2O

    NASA Astrophysics Data System (ADS)

    Röska, B.; Park, S.-H.; Yoshimori, Y.; Kimura, K.; Kimura, T.

    2017-09-01

    An anomalous increase in the real part of dielectric response is observed in Mn0.5Fe0.5AlPO4(OH)2H2O while cooling to ~70 K. This is addressed to field-induced proton dynamics in a short hydrogen bond of 2.480(3) Å. The absence of discontinuities in heat capacity curves above the Néel temperature (T N  ≈  7 K) excludes a paraelectric to antiferroelectric phase transition. Upon the application of mild hydrostatic pressures below 1.6 GPa, the maximum in the dielectric response is shifted from 70 K to lower temperatures near 2 K. This explains a narrow correlation between proton transfer and the compression of the short hydrogen bond length.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  10. Communication: THz absorption spectrum of the CO2-H2O complex: Observation and assignment of intermolecular van der Waals vibrations

    NASA Astrophysics Data System (ADS)

    Andersen, J.; Heimdal, J.; Mahler, D. W.; Nelander, B.; Larsen, R. Wugt

    2014-03-01

    Terahertz absorption spectra have been recorded for the weakly bound CO2-H2O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H2O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this systems' flat intermolecular potential energy surface. A (semi)-empirical value for the zero-point energy of 273 ± 15 cm-1 from the class of intermolecular van der Waals vibrations is proposed and the combination with high-level quantum chemical calculations provides a value of 726 ± 15 cm-1 for the dissociation energy D0.

  11. Communication: THz absorption spectrum of the CO2-H2O complex: observation and assignment of intermolecular van der Waals vibrations.

    PubMed

    Andersen, J; Heimdal, J; Mahler, D W; Nelander, B; Larsen, R Wugt

    2014-03-07

    Terahertz absorption spectra have been recorded for the weakly bound CO2-H2O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H2O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this systems' flat intermolecular potential energy surface. A (semi)-empirical value for the zero-point energy of 273 ± 15 cm(-1) from the class of intermolecular van der Waals vibrations is proposed and the combination with high-level quantum chemical calculations provides a value of 726 ± 15 cm(-1) for the dissociation energy D0.

  12. 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

  13. Proton conducting system (ImH2)2SeO4·2H2O investigated with vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Zięba, Sylwia; Mizera, Adam; Pogorzelec-Glaser, Katarzyna; Łapiński, Andrzej

    2017-06-01

    Imidazolium selenate dihydrate (ImH2)2SeO4·2H2O crystals have been investigated using Raman and IR spectroscopy. Experimental data were supported by the quantum-chemical calculations (DFT), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. The imidazolium selenate dihydrate crystal exhibits high proton conductivity of the order of 10- 1 S/m at T = 333 K. The spectra of this compound are dominated by bands related to the lattice modes, the internal vibrations of the protonated imidazole cation, selenate anion, water molecules, and hydrogen bonds network. For the imidazolium selenate dihydrate crystal, the formal classification of the fundamental modes has been carried out.

  14. 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.

  15. 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.

  16. 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.

  17. Coupled-cluster reaction barriers of HO2+H2O+O3: An application of the coupled-cluster//Kohn-Sham density functional theory model chemistry.

    PubMed

    Viegas, Luís P; Varandas, António J C

    2014-03-15

    In this work, we report a theoretical investigation concerning the use of the popular coupled-cluster//Kohn-Sham density functional theory (CC//KS-DFT) model chemistry, here applied to study the entrance channel of the HO2+H2O+O3 reaction, namely by comparing CC//KS-DFT calculations with KS-DFT, MRPT2//CASSCF, and CC//CASSCF results from our previous investigations. This was done by performing single point energy calculations employing several coupled cluster methods and using KS-DFT geometries optimized with six different functionals, while conducting a detailed analysis of the barrier heights and topological features of the curves and surfaces here obtained. The quality of this model chemistry is critically discussed in the context of the title reaction and also in a wider context. Copyright © 2013 Wiley Periodicals, Inc.

  18. 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.

  19. 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

  20. Weak ferromagnetic order breaking the threefold rotational symmetry of the underlying kagome lattice in CdC u3(OH) 6(NO3)2.H2O

    NASA Astrophysics Data System (ADS)

    Okuma, Ryutaro; Yajima, Takeshi; Nishio-Hamane, Daisuke; Okubo, Tsuyoshi; Hiroi, Zenji

    2017-03-01

    Novel magnetic phases are expected to occur in highly frustrated spin systems. Here, we study the structurally perfect kagome antiferromagnet CdC u3(OH) 6(NO3)2.H2O by magnetization, magnetic torque, and heat capacity measurements using single crystals. An antiferromagnetic order accompanied by a small spontaneous magnetization that surprisingly is confined in the kagome plane sets in at TN˜4 K , well below the nearest-neighbor exchange interaction J /kB=45 K . This suggests that a unique "q =0 " type 120∘ spin structure with "negative" (downward) vector chirality, which breaks the underlying threefold rotational symmetry of the kagome lattice and thus allows a spin canting within the plane, is exceptionally realized in this compound rather than a common one with "positive" (upward) vector chirality. The origin is discussed in terms of the Dzyaloshinskii-Moriya interaction.

  1. Precision Cavity-Enhanced Dual-Comb Spectroscopy: Application to the Gas Metrology of CO_2, H_2O, and N_2O.

    NASA Astrophysics Data System (ADS)

    Fleisher, Adam J.; Long, David A.; Hodges, Joseph T.

    2017-06-01

    With inherent simplicity, mutual phase coherence, and a high degree of user control, electro-optic frequency combs are amenable to both dual-comb spectroscopy and cavity-enhanced comb spectroscopy. This combination of fast, multiplexed spectroscopy, with an effective absorption pathlength >1 km, is used here to perform line-by-line metrology of the gas-phase absorption spectra of CO_2, H_2O, and N_2O in the near-infrared. We report absolute transition frequency with precision better than 1 MHz in 1 s of spectral acquisition per transition using a comb with an instantaneous optical bandwidth of 6 GHz, tunable over the entire 6240-6370 \\wn range. A full model for the electric field transmitted through the enhancement cavity (even in the presence of strong molecular absorption and dispersion) will be discussed. I. Coddington et al., Optica 3, 414 (2016) B. Bernhardt et al., Nat. Photonics 4, 55 (2010)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Overtone vibrational spectroscopy in H2-H2O complexes: a combined high level theoretical ab initio, dynamical and experimental study.

    PubMed

    Ziemkiewicz, Michael P; Pluetzer, Christian; Nesbitt, David J; Scribano, Yohann; Faure, Alexandre; van der Avoird, Ad

    2012-08-28

    First results are reported on overtone (v(OH) = 2 ← 0) spectroscopy of weakly bound H(2)-H(2)O complexes in a slit supersonic jet, based on a novel combination of (i) vibrationally mediated predissociation of H(2)-H(2)O, followed by (ii) UV photodissociation of the resulting H(2)O, and (iii) UV laser induced fluorescence on the nascent OH radical. In addition, intermolecular dynamical calculations are performed in full 5D on the recent ab initio intermolecular potential of Valiron et al. [J. Chem. Phys. 129, 134306 (2008)] in order to further elucidate the identity of the infrared transitions detected. Excellent agreement is achieved between experimental and theoretical spectral predictions for the most strongly bound van der Waals complex consisting of ortho (I = 1) H(2) and ortho (I = 1) H(2)O (oH(2)-oH(2)O). Specifically, two distinct bands are seen in the oH(2)-oH(2)O spectrum, corresponding to internal rotor states in the upper vibrational manifold of Σ and Π rotational character. However, none of the three other possible nuclear spin modifications (pH(2)-oH(2)O, pH(2)-pH(2)O, or oH(2)-pH(2)O) are observed above current signal to noise level, which for the pH(2) complexes is argued to arise from displacement by oH(2) in the expansion mixture to preferentially form the more strongly bound species. Direct measurement of oH(2)-oH(2)O vibrational predissociation in the time domain reveals lifetimes of 15(2) ns and <5(2) ns for the Σ and Π states, respectively. Theoretical calculations permit the results to be interpreted in terms of near resonant energy levels and intermolecular alignment of the H(2) and H(2)O wavefunctions, providing insight into predissociation dynamical pathways from these metastable levels.

  8. 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.

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

    PubMed

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

    2016-01-01

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

  10. 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.

  11. 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

  12. Crystal and molecular structure of ammonium beryllium sulfate dihydrate, (NH4)2Be(SO4)2·2H2O

    NASA Astrophysics Data System (ADS)

    Wildner, M.; Karadjova, V.; Marinova, D.; Georgiev, M.; Stoilova, D.

    2012-08-01

    In this paper we report the crystal and molecular structure of the title compound, (NH4)2Be(SO4)2·2H2O, as determined by single-crystal X-ray diffraction and vibrational spectroscopy data. (NH4)2Be(SO4)2·2H2O crystallizes in the monoclinic space group P21/c (a = 11.448(2), b = 11.876(2), c = 7.439(1) Å, β = 96.64(1)°, V = 1004.6 Å3, Z = 4, R1 = 0.036 for 3753 Fo > 4σ(Fo) and 185 variables), and is isotypic with the respective potassium and rubidium sulfates and the potassium selenate. The crystal structure is built from three-membered tetrahedral chain fragments, consisting of a central BeO2(H2O)2 group and two adjacent SO4 tetrahedra. These building blocks are linked by rather strong hydrogen bonds of the water molecules (O⋯O = 2.66-2.77 Å) and by moderate to weak hydrogen bonds of the NH4 groups (N⋯O ≥ 2.78 Å) to a three-dimensional framework structure. The infrared bands corresponding to the stretching modes ν3 and ν1 as well as the Raman band corresponding to ν1 of the SO42- ions are observed in the spectra as doublets, thus reflecting the existence of two crystallographically different sulfate ions. The spectroscopic experiments reveal that the sulfate tetrahedra exhibit a remarkably large extent of energetic distortion as deduced from the values of Δν3 (site group splitting) and Δνmax (the difference between the highest and the lowest wavenumbered component of the stretching modes) (111 and 183.5 cm-1, respectively), which could not be predicted from the structural data. The comparison of the spectral region widths of the stretching and bending modes of the SO42- ions allows us to assume that these ions undergo a stronger energetic distortion with respect to the Ssbnd O bond lengths than that with respect to the Osbnd Ssbnd O bond angles. The water librations couple intensively with both the translatory modes of the Be2+ cations (BeO4 skeleton vibrations) and the normal modes of the sulfate ions, thus producing small isotopic

  13. [Raman spectroscopic study of the complex and quantitative analysis in the system CuCl2-H2O and FeCl3-H2O].

    PubMed

    Yang, Dan; Xu, Wen-Yi

    2011-10-01

    In the present paper, the Raman peaks of complex in the CuCl2-H2O system and FeCl3-H2O system were studied in detail. In the CuCl2-H2O system, the superimposed characteristic peaks of various complex formed by Cu2+ and Cl- (such as [CuCl4]2- and [CuCl6]4-) may be formed the peak of 286 cm(-1), and the superimposed characteristic peaks of various complex formed by Cu2+ hydrate([Cu(H2O)4]2+ and [Cu(H2O)6]2+ based) may be formed the peak of 412 cm(-1); Through the analysis of peak parameters, we has founded two quantitative relationships: (1) The peak intensity ratio (I1 I3I 400 or I2/I3 400) of 286 cm(-1) (or 412 cm(-1)) and OH stretching Raman spectrum of water (at 3 400 cm(-1)) and concentration; (2) The integral area of 286 cm(-1) (or 412 cm(-1)) and concentration. In the FeCl3-H2O system, 173 and 331 cm(-1) might be attributed to [FeCl4]- that is the most common form of FeCl3 complex in aqueous solution. The superimposed characteristic peaks of various complex formed by Fe3+ and Cl- (such as [FeCl]2+, [FeCl2]+ etc) may be formed the broad peak of 173 cm(-1), and the superimposed characteristic peaks of various complex formed by Fe3+ hydrate([Fe(H2O)4]3+ and [Fe(H2O)6]3+ based) may be formed the broad weak peak behind of 331 cm(-1). Through the analysis of peak parameters, we has founded two quantitative relationships: (1) The integral area of 331 cm(-1) (A2) and concentration; (2) The integral area ratio of 173 and 331 cm(-1) (A1/A2) and concentration.

  14. 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

  15. 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

  16. Competitive formation of b(2) and c(2)-H2O ions from b(3) ions containing Asp residue during tandem mass spectrometry: the influence of neighboring Arg.

    PubMed

    Guo, Mengzhe; Guo, Cheng; Pan, Yuanjiang

    2014-08-01

    The fragmentation of b3 ions derived from protonated Arg-Xxx-Asp-Ala-Ala (Xxx = Ala, Asp, Glu, Cys) and Arg-Xxx-Glu-Ala-Ala was investigated by electrospray ionization tandem mass spectrometry (MS (n) ) with collision-induced dissociation. A particular ion, which is 1 Da less than b2 ion, is shown to be the c2-H2O ion. The mechanism for its formation involved the aspartic acid in the third position easily losing anhydride to form a c2 ion, which then lost water to form an eight-membered ring of azacyclooctane derivative under the participation of the guanidine of the N-terminal arginine. However, this phenomenon was not observed when the aspartic acid was replaced by glutamic acid. The Amber program was used to determine the conformation of the original c2 residue from the dynamic energy perspective, and then density functional theory-based calculations and changing N-terminal amino acid from arginine to phenylalanine supported this mechanism.

  17. 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

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  1. 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

  2. Exploring the rich energy landscape of sulfate-water clusters SO4(2-) (H2O)(n=3-7): an electronic structure approach.

    PubMed

    Lambrecht, Daniel S; Clark, Gary N I; Head-Gordon, Teresa; Head-Gordon, Martin

    2011-10-20

    We present a reinvestigation of sulfate-water clusters SO4(2-) (H2O)(n=3-7), which involves several new aspects. Using a joint molecular mechanics/first principles approach, we perform exhaustive searches for stable cluster geometries, showing that the sulfate-water landscape is much richer than anticipated previously. We check the compatibility of the new structures with experiment by comparing vertical detachment energies (VDEs) calculated at the B3LYP/6-311++G** level of theory and determine the energetic ordering of the isomers at the RI-MP2/aug-cc-pVTZ level. Our results are bench-marked carefully against reference energies of estimated CCSD(T)/aug-cc-VTZ quality and VDEs of CCSD(T)/aug-cc-pVDZ quality. Furthermore, we calculate anharmonic vibrational corrections for up to the n = 6 clusters, which are shown to be significant for isomer energy ordering. We use energy decomposition analysis (EDA) based on the absolutely localized fragment (ALMO) expansion to gain chemical insight into the binding motifs.

  3. 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.

  4. CO2, H2O, and chlorophyll fluorescence retrieved from OCO-2 measurements using a fast radiative transfer model approximating multiple scattering effects

    NASA Astrophysics Data System (ADS)

    Reuter, Maximilian; Bovensmann, Heinrich; Buchwitz, Michael; Burrows, John P.; Heymann, Jens; Noël, Stefan; Rozanov, Vladimir; Schneising, Oliver

    2017-04-01

    Carbon dioxide is the most important anthropogenic greenhouse gas. Its global increasing concentration in the Earth's atmosphere is the main driver for global climate change. In spite of its importance, there are still large uncertainties on its global sources and sinks. Satellite measurements have the potential to reduce these surface flux uncertainties. However, the demanding accuracy requirements usually involve the need for precise radiative transfer calculations in a scattering atmosphere. These can be computationally so expensive that hundreds or thousands of CPU cores are need to keep up with the data stream of an instrument like OCO-2. Future instruments will further increase the amount of soundings at least by an order of magnitude. A radiative transfer model has been developed approximating scattering effects by multiple scattering at an optically thin scattering layer reducing the computational costs by several orders of magnitude. The model can be used to simulate the radiance in all three OCO-2 spectral bands allowing the simultaneous retrieval of CO2, H2O, and chlorophyll fluorescence. First retrieval results for OCO-2 data will be presented.

  5. A new aqua­manganese(II) oxalate phosphate, Mn(C2O4)Mn3(PO4)2(H2O)2

    PubMed Central

    Zheng, Juan; Shen, Yuxia; Song, Tao; Zhang, Aiyun

    2009-01-01

    The title salt, diaquatetra­manganese(II) oxalate bis[ortho­phos­phate(V)], Mn4(C2O4)(PO4)2(H2O)2, was synthesized hydro­thermally and displays a three-dimensional framework structure. The asymmetric unit consists of two different MnII centers, half of an oxalate anion, a phosphate group and a coordinated water mol­ecule. A crystallographic inversion center is located at the mid-point of the oxalate C—C bond. The distorted octa­hedral MnO6 and the tetra­gonal pyramidal MnO5 centers are linked through bridging oxalate and phosphate groups. The water mol­ecule also has a weaker bonding contact to the five-coordinate Mn atom, which consequently exhibits a distorted octa­hedral geometry and also bridges the independent Mn atoms. The water mol­ecule is a donor for intra- and inter­molecular O—H⋯O hydrogen bonds. PMID:21583724

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. A detailed test study of barrier heights for the HO2 + H2O + O3 reaction with various forms of multireference perturbation theory.

    PubMed

    Viegas, Luís P; Varandas, António J C

    2012-03-21

    We report an ab initio multireference perturbation theory investigation of the HO(2) + H(2)O + O(3) reaction, with particular emphasis on the barrier heights for two possible reaction mechanisms: oxygen abstraction and hydrogen abstraction, which are identified by two distinct saddle points. These saddle points and the corresponding pre-reactive complexes were optimized at the CASSCF(11,11) level while the single point energies were calculated with three different MRPT2 theories: MRMP, CASPT2, and SC-NEVPT2. Special attention has been drawn on the "intruder state" problem and the effect of its corrections on the relative energies. The results were then compared with single reference coupled-cluster methods and also with our recently obtained Kohn-Sham density functional theory (KS-DFT) calculations [L. P. Viegas and A. J. C. Varandas, Chem. Phys., (2011)]. It is found that the relative energies of the pre-reactive complexes have a very good agreement while the MRPT2 classical barrier heights are considerably higher than the KS-DFT ones, with the SC-NEVPT2 calculations having the highest energies between the MRPT2 methods. Possible explanations have been given to account for these differences. © 2012 American Institute of Physics

  11. 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.

  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. Solution and single crystal spectroscopic characterization of (PPh 4) 2[Fe(CN) 5(imidazole)]·2H 2O

    NASA Astrophysics Data System (ADS)

    Tchouka, Heloïse; Meetsma, Auke; Molnár, Gábor; Rechignat, Lionel; Browne, Wesley R.

    2011-07-01

    The compound (PPh 4) 2[Fe III(CN) 5(im)]·2H 2O ( 1) together with its 13C labeled analogue have been synthesized (where im is imidazole) and characterized by UV/Vis, LD, IR, Raman and resonance Raman spectroscopy both in solution, powder and single crystalline form. The low spin state of the metal center, Fe III, was confirmed by MCD, EPR and 57Fe Mössbauer spectroscopies. Polarized Raman spectroscopic studies on a single crystal of 1 show the strong dependence of the stretching cyano ligand vibrations on crystal orientation relative to the direction of laser polarization and allows for assignment of all CN vibrational modes. Raman, UV/Vis absorption, LD and MCD spectroscopy both in the solid state and in solution state allowed for the discrimination of the effect of protonation of the imidazole ligand and hydrogen bonding to the cyano ligands on the complex. The combined spectroscopic data demonstrates that in addition to the protonation state of the imidazole, hydrogen bonding interactions with the cyano ligands both in the solid state as well as in solution have a profound influence on the electronic properties of 1.

  15. Phase transformations during de- and rehydration of scholzite CaZn2(PO4)2·2H2O

    NASA Astrophysics Data System (ADS)

    Afflerbach, S.; Kowald, T.; Trettin, R.

    2017-10-01

    The reversibility of the formation of CaZn2(PO4)2·H2O after dehydration of CaZn2(PO4)2·2H2O is proven by combining methods of thermal analysis and X-ray diffraction. The dehydration enthalpy is determined from differential calorimetric analysis. Scanning electron microscopy (SEM) is utilized to investigate effects of respective reactions on the particle morphology. The dehydration of scholzite to the monohydrate is also probed by temperature dependent in-situ X-ray diffraction. The measured diffraction patterns reveal a structural change in the crystal lattice upon dehydration, which is yet unknown. Lattice parameters of scholzite are analyzed as a function of temperature to trace structural changes. Expansion coefficients of the lattice constant c and of the unit cell volume of scholzite are determined. In combination with results from SEM, an understanding of the corresponding de- and rehydration mechanism is emphasized with regard to a possible application of the material in thermochemical energy storage and -conversion.

  16. 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.

  17. An internally consistent set of thermodynamic data for twentyone CaO-Al2O3-SiO2- H2O phases by linear parametric programming

    NASA Astrophysics Data System (ADS)

    Halbach, Heiner; Chatterjee, Niranjan D.

    1984-11-01

    The technique of linear parametric programming has been applied to derive sets of internally consistent thermodynamic data for 21 condensed phases of the quaternary system CaO-Al2O3-SiO2-H2O (CASH) (Table 4). This was achieved by simultaneously processing: a) calorimetric data for 16 of these phases (Table 1), and b) experimental phase equilibria reversal brackets for 27 reactions (Table 3) involving these phases. Calculation of equilibrium P-T curves of several arbitrarily picked reactions employing the preferred set of internally consistent thermodynamic data from Table 4 shows that the input brackets are invariably satisfied by the calculations (Fig. 2a). By contrast, the same equilibria calculated on the basis of a set of thermodynamic data derived by applying statistical methods to a large body of comparable input data (Haas et al. 1981; Hemingway et al. 1982) do not necessarily agree with the experimental reversal brackets. Prediction of some experimentally investigated phase relations not included into the linear programming input database also appears to be remarkably successful. Indications are, therefore, that the thermodynamic data listed in Table 4 may be used with confidence to predict geologic phase relations in the CASH system with considerable accuracy. For such calculated phase diagrams and their petrological implications, the reader's attention is drawn to the paper by Chatterjee et al. (1984).

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  4. 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.

  5. Apoptosis-inducing Effect of a Palladium(II) Complex-[PdCl(terpy)](sac).2H2O] on Ehrlich Ascites Carcinoma (EAC) in Mice.

    PubMed

    Ikitimur-Armutak, Elif I; Ulukaya, Engin; Gurel-Gurevin, Ebru; Yaylim, Ilhan; Isbilen-Basok, Banu; Sennazli, Gulbin; Yuzbasioglu-Ozturk, Gulay; Sonmez, Kivilcim; Celik, Faruk; Kucukhuseyin, Ozlem; Korkmaz, Gurbet; Yilmaz, Veysel T; Zeybek, Sakir Umit

    2016-01-01

    New compounds for cancer treatment are needed due to persistenly unsatisfactory management of cancer. [PdCl(terpy)](sac)·2H2O] (sac=saccharinate, and terpy=2,2':6',2"-terpyridine) is a compound synthesized for this purpose. We investigated its anti-proliferative and pro-apoptotic effects on Ehrlich Ascites Carcinoma (EAC) in vivo. 42 Balb-c female mice were subcutaneously (s.c.) injected with EAC cells (1st day) and then randomly divided into 5 groups: control (0.9% NaCl), complex (2 mg/kg), complex (3 mg/kg) cisplatin (4 mg/kg) and paclitaxel (12.5 mg/kg). On the 5th and 12th day animals were drug administrated. At 14th day, animals were sacrificed. Expression of cell death and/or cell cycle-related markers (Bcl-2, Bax, active caspase-3, p53, PCNA) and apoptosis were investigated immunohisto-chemically. Survival-related markers (Akt, GSK-3β, IGF-1R, IR, IRS-1, p70S6K, PRAS40) were evaluated by luminex analysis. Expression of p53, PCNA, Bcl-2 was found decreased (p<0.001) and that of active caspase-3, Bax, and apoptotic cells was found increased (p<0.001) in all groups. The survival-related markers did not show any statistical difference in complex groups. The Pd(II)-complex seems to have a strong anticancer activity on EAC by inducing apoptosis via both suppression of proliferation and activation of apoptosis in vivo, similar to the effects of cisplatin and paclitaxel. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  6. 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.

  7. The Stability of Hydrous Silicates in Earth's Lower Mantle: Experimental constraints from the System MgO-Al2O3-SiO2-H2O

    NASA Astrophysics Data System (ADS)

    Walter, M. J.; Thomson, A. R.; Wang, W.; Lord, O. T.; Kleppe, A. K.; Ross, J.; Kohn, S. C.

    2014-12-01

    Laser-heated diamond anvil cell experiments were performed at pressures from ~ 30 to 125 GPa on bulk compositions in the system MgO-Al2O3-SiO2-H2O (MASH) to constrain the stability of hydrous phases in Earth's lower mantle. Phase identification in run products by synchrotron powder diffraction reveals a consistent set of stability relations for the high-pressure, dense hydrous silicate phases D and H. Experiments show that aluminous phase D is stable to ~ 55 GPa. Aluminous phase H becomes stable at ~ 40 GPa and remains stable to higher pressures throughout the lower mantle depth range in both model peridotitic and basaltic lithologies. Preliminary FEG-probe analyses indicate that Phase H is alumina-rich at ~ 50 GPa, with only 5 to 10 wt% each of MgO and SiO2. Variations in ambient unit cell volumes show that Mg-perovskite becomes more aluminous with pressure throughout the pressure range studied, and that Phase H may become more Mg- and Si-rich with pressure. We also find that at pressures above ~ 90 GPa stishovite is replaced in Si-rich compositions by seifertite, at which point there is a corresponding increase in the Al-content of phase H. The melting curves of MASH compositions have been determined using thermal perturbations in power versus temperature curves, and are observed to be shallow with dT/dP slopes of ~ 4K/GPa. Our results show that hydrated peridotitic or basaltic compositions in the lower mantle should be partially molten at all depths along an adiabatic mantle geotherm. Aluminous Phase H will be stable in colder, hydrated subducting slabs, potentially to the core-mantle boundary. Thus, aluminous phase H is the primary vessel for transport of hydrogen to the deepest mantle, but hydrous silicate melt will be the host of hydrogen at ambient mantle temperatures.

  8. 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.

  9. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  11. Structural characterisation of [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O donor-acceptor complex

    NASA Astrophysics Data System (ADS)

    Sieklucka, B.; Łasocha, W.; Proniewicz, L. M.; Podgajny, R.; Schenk, H.

    2000-03-01

    The bimetallic [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O is characterised by single-crystal X-ray diffraction [S.G. P2 1/ m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D4h geometry with average dimensions Pt(1)-N 2.042(2) and Pt(2)-N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D4d configuration with average dimensions W(1)-C 2.164(13), C-N 1.140(12), W(1)-N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)-W(1), W(1) ∗ separations of 4.77(2), 4.55(2) ∗ and Pt(1)-W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO 3- between parallel [Pt(1)(NH 3) 4] 2+ planes and the second consists of [W(CN) 8] 3- interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH 3) 4] 2+. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH 3 ligands, water molecules and oxygen atoms of NO 3- counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer.

  12. 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.

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

    PubMed

    Sujith, K S; Ramachandran, C N

    2016-02-07

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

  14. Molecular dynamic simulations of selective self-diffusion of CH4/CO2/H2O/N2 in coal

    NASA Astrophysics Data System (ADS)

    Song, Y.; Jiang, B.; Li, F. L.

    2017-06-01

    The self-diffusion coefficients (D) of CH4/CO2/H2O/N2 at a relatively broad range of temperatures(298.15∼ 458.15K)and pressures (1∼6MPa) under the NPT, NPH, NVE, and NVT ensembles were obtained after the calculations of molecular mechanics(MM), annealing kinetics(AK), giant canonical Monte Carlo(GCMC), and molecular dynamics (MD) based on Wiser bituminous coal model (WM). The Ds of the adsorbates at the saturated adsorption configurations are D CH4418K. The average swelling ratios manifest as H2O (14.7∼35.18%)>CO2 (13.38∼32.25%)>CH4 (15.35∼23.71%)> N2 (11.47∼22.14%) (NPH, 1∼6MPa). There exits differences in D, swelling ratios and E among various ensembles, indicating that the selection of ensembles has an important influence on the MD calculations for self-diffusion coefficients.

  15. The effects of repeated ingestion of high and low glucose-electrolyte solutions on gastric emptying and blood 2H2O concentration after an overnight fast.

    PubMed

    Evans, Gethin H; Shirreffs, Susan M; Maughan, Ronald J

    2011-12-01

    The addition of carbohydrate to drinks designed to have a role in rehydrating the body is commonplace. The gastric emptying and fluid uptake characteristics following repeated ingestion of drinks with high and low glucose concentrations were examined in eight subjects (three male and five female). Following a 13 h fluid restriction period, the subjects ingested a volume of test solution amounting to 3 % of the initial body mass over a period of 60 min. Test drinks were 2 and 10 % glucose-electrolyte solutions with osmolalities of 189 (SD 3) and 654 (SD 3) mOsm/kg, respectively. The initial bolus of each test solution contained 10 g of (2)H(2)O. Blood samples were collected throughout drinking and for 60 min afterwards. Gastric volumes were determined via gastric aspiration at 15 min intervals for 120 min. No difference between trials in total stomach volume was observed until 30 min after the ingestion of the first bolus of test drink, but blood (2)H concentration was increased during both trials 10 min after ingestion of the first bolus. Blood (2)H concentration was greater at this time point during the 2 % glucose trial than during the 10 % glucose trial and remained higher for the duration of the trial with the exception of one time point. Urine volume at the end of the trial was greater in the 2 % glucose trial than in the 10 % glucose trial. It is concluded that the reduced overall rate of fluid uptake following ingestion of the 10 % glucose solution was due largely to a relatively slow rate of gastric emptying.

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

    PubMed Central

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

    2005-01-01

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

  18. 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.

  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. 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.

  1. Kramers-Kronig dispersive analysis and optical properties in the infrared, and revised vibrational behavior of orthorhombic Na2[Fe(CN)5NO].2H2O

    NASA Astrophysics Data System (ADS)

    Piro, Oscar E.; Castellano, E. E.; Güida, J. A.; Aymonino, P. J.

    1989-01-01

    The optical parameters (namely, the complex dielectric tensor and refractive indexes) of sodium nitroprusside dihydrate (SNP), Na2[Fe(CN)5NO].2H2O (orthorhombic, space group D122h) in the infrared (ir) region 1550-2250 cm-1, which includes the fundamental bands of the strongly polar NO stretching mode, are determined. For this purpose, transverse-electric (TE) reflectance data on the (100) and (010) faces of SNP in the range 250-4000 cm-1 were analyzed by the Kramers-Kronig (KK) dispersive method. The values obtained for the optical parameters were employed to get the wave numbers of transverse (ν¯TO) and longitudinal (ν¯LO) ir-active optic NO stretching modes of symmetry species B3u (polarized along the a axis) and B2u (polarized along b). It is shown that obtaining sharp peaks for accurate frequency measurements of the strong TO NO modes by transmission spectroscopy would require impossibly thin crystal films (of thicknesses of a few tenths of a micro- meter), much smaller than the practical limit (a few tens of micrometers). Hence, our room-temperature values for ν¯TO of 1944 cm-1 (B3u mode) and 1942 cm-1 (B2u mode) should be considered more reliable than the corresponding transmission values reported in the literature. The KK dielectric tensor was also employed to compute the transverse-magnetic (TM), off-axis transmittance spectra of (100) and (010) SNP plates in the NO stretching region. These calculations are in good agreement with spectroscopic data and exhibit sharp peaks at 1964 and 1953 cm-1 due to the coupling of B3u and B2u LO modes, respectively, with the ir radiation. Our results show that strongly absorbing LO modes polarized perpendicularly to the plate can be easily identified through the variation of their band intensities with the incident angle of the ir beam and that their frequency can be accurately measured in relatively thick samples. The calculated TM-polarized, off-axis reflectance spectrum from the (010) face of thick SNP crystals

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    Serpentinite-hosted hydrothermal systems have attracted considerable attention as sites of abiotic organic synthesis and as habitats for the earliest microbial communities. Here, we report a systematic isotopic study of a new serpentinite-hosted system: the Hakuba Happo hot spring in the Shiroumadake area, Japan (36 °42‧N, 137 °48‧E). We collected water directly from the hot spring from two drilling wells more than 500 m deep; all water samples were strongly alkaline (pH > 10) and rich in H2 (201-664 μmol/L) and CH4 (124-201 μmol/L). Despite the relatively low temperatures (50-60 °C), thermodynamic calculations suggest that the H2 was likely derived from serpentinization reactions. Hydrogen isotope compositions for Happo #1 (Happo #3) were found to be as follows: δD-H2 = - 700 ‰ (- 710 ‰), δD-CH4 = - 210 ‰ (- 300 ‰), and δD-H2 O = - 85 ‰ (- 84 ‰). The carbon isotope compositions of methane from Happo #1 and #3 were found to be δ13C = - 34.5 ‰ and - 33.9 ‰, respectively. The CH4-H2-H2O hydrogen isotope systematics indicate that at least two different mechanisms were responsible for methane formation. Happo #1 has a similar hydrogen isotope compositions to other serpentinite-hosted systems reported previously. The elevated δD-CH4 (with respect to the equilibrium relationship) suggests that the hydrogen of the Happo #1 methane was not sourced from molecular hydrogen but was derived directly from water. This implies that the methane may not have been produced via the Fischer-Tropsch-type (FTT) synthesis but possibly by the hydration of olivine. Conversely, the depleted δD-CH4 (with respect to the equilibrium relationship) in Happo #3 suggests the incorporation of biological methane. Based on a comparison of the hydrogen isotope systematics of our results with those of other serpentinite-hosted hydrothermal systems, we suggest that abiotic CH4 production directly from H2O (without mediation by H2) may be more common in serpentinite

  3. Redox process catalysed by growing crystal-strengite, FePO4,2H2O, crystallizing from solution with iron(II) and hydroxylamine

    NASA Astrophysics Data System (ADS)

    Lundager Madsen, Hans Erik

    2014-09-01

    In an attempt to grow pure crystals of the iron(II) phosphate vivianite, Fe3(PO4)2,8H2O, from a solution of Mohr's salt, Fe(NH4)2(SO4)2,6H2O, added to a solution of ammonium phosphate, hydroxylammonium chloride, NH3OHCl, was added to the iron(II) stock solution to eliminate oxidation of iron(II) by oxygen from the air. However, the effect turned out to be the opposite of the expected: whereas hydroxylamine reduces iron(III) in bulk solution, it acted as a strong oxidant in the presence of growing iron phosphate crystals, causing the crystallization of the iron(III) phosphate strengite, FePO4,2H2O, as the only solid phase. Evidently the crystal surface catalyses oxidation of iron(II) by hydroxylamine. The usual composite kinetics of spiral growth and surface nucleation was found. The surface-nucleation part yielded edge free energy λ in the range 12-45 pJ/m, virtually independent of temperature and in the range typical for phosphates of divalent metals. The scatter of values for λ presumably arises from contributions from different crystal forms to the overall growth rate. The low mean value points to strong adsorption of iron(II), which is subsequently oxidized at the crystal surface, forming strengite. The state of the system did not tend to thermodynamic equilibrium, but to a metastable state, presumably controlled by the iron(II) rich surface layer of the crystal. In addition to crystal growth, it was possible to measure nucleation kinetics by light scattering (turbidimetry). A point of transition from heterogeneous to homogeneous nucleation was found, and from the results for the homogeneous domain a rather precise value of crystal surface free energy γ=55 mJ/m2 was found. This is a relatively low value as well, indicating that the redox process plays a role already at the nucleation stage.

  4. Monitoring of the ultrafast vibrational kinetic during formation of photo-induced linkage isomers in Na2[Fe(CN)5NO]·2H2O single crystal.

    NASA Astrophysics Data System (ADS)

    Galle, G.; Nicoul, M.; Woike, Th.; Schaniel, D.; Freysz, E.

    2013-03-01

    A femtosecond visible pump - infrared probe time resolved absorption experiment makes it possible to reveal the ultrafast vibrationnal kinetic associated to formation of light-induced linkage isomers in Na2[Fe(CN)5NO]2H2O (SNP) single crystals.

  5. Exploration of the potential energy surfaces, prediction of atmospheric concentrations, and prediction of vibrational spectra for the HO2...(H2O)n (n = 1-2) hydrogen bonded complexes.

    PubMed

    Alongi, Kristin S; Dibble, Theodore S; Shields, George C; Kirschner, Karl N

    2006-03-16

    The hydroperoxy radical (HO2) plays a critical role in Earth's atmospheric chemistry as a component of many important reactions. The self-reaction of hydroperoxy radicals in the gas phase is strongly affected by the presence of water vapor. In this work, we explore the potential energy surfaces of hydroperoxy radicals hydrogen bonded to one or two water molecules, and predict atmospheric concentrations and vibrational spectra of these complexes. We predict that when the HO2 concentration is on the order of 10(8) molecules x cm(-3) at 298 K, that the number of HO2...H2O complexes is on the order of 10(7) molecules x cm(-3) and the number of HO2...(H2O)2 complexes is on the order of 10(6) molecules x cm(-3). Using the computed abundance of HO2...H2O, we predict that, at 298 K, the bimolecular rate constant for HO2...H2O + HO2 is about 10 times that for HO2 + HO2.

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

    NASA Astrophysics Data System (ADS)

    Boonchom, Banjong; Danvirutai, Chanaiporn; Vittayakorn, Naratip

    2011-01-01

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

  7. Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca2(C2O4)Cl2·2H2O and its twinned triclinic heptahydrate analog

    NASA Astrophysics Data System (ADS)

    Piro, Oscar E.; Echeverría, Gustavo A.; González-Baró, Ana C.; Baran, Enrique J.

    2017-06-01

    Synthetic novgorodovaite analog Ca2(C2O4)Cl2·2H2O is identical to its natural counterpart. It crystallizes in the monoclinic I2/m space group with a = 6.9352(3), b = 7.3800(4), c = 7.4426(3) Å, β = 94.303(4)°, V = 379.85(3) Å3 and Z = 2. The heptahydrate analog, Ca2(C2O4)Cl2·7H2O, crystallizes as triclinic twins in the P \\overline{1} space group with a = 7.3928(8), b = 8.9925(4), c = 10.484(2) Å, α = 84.070(7), β = 70.95(1), γ = 88.545(7)°, V = 655.3(1) Å3 and Z = 2. The crystal packing of both calcium oxalate-chloride double salts favors the directional bonding of oxalate, C2O4 2-, ligands to calcium ions as do other related calcium oxalate minerals. The π-bonding between C and O atoms of the C2O4 2- oxalate group leaves sp 2-hydridised orbitals of the oxygen atoms available for bonding to Ca. Thus, the Ca-O bonds in both calcium oxalate-chloride double salts are directed so as to lie in the plane of the oxalate group. This behavior is reinforced by the short O···O distances between the oxygens attached to a given carbon atom, which favors them bonding to a shared Ca atom in bidentate fashion. Strong bonding in the plane of the oxalate anion and wide spacing perpendicular to that plane due to repulsion between oxalate π-electron clouds gives rise to a polymerized structural units which are common to both hydrates, explaining the nearly equal cell constants 7.4 Å which are defined by the periodicity of Ca-oxalate chains in the framework (monoclinic b ≈ triclinic a). When compared with novgorodovaite, the higher water content of Ca2(C2O4)Cl2·7H2O leads to some major differences in their structures and ensuing physical properties. While novgorodovaite has a three-dimensional framework structure, in the higher hydrate, the highly polar water molecules displace chloride ions from the calcium coordination sphere and surround them through OwH···Cl hydrogen bonds. As a result, polymerization in Ca2(C2O4)Cl2·7H2O solid is limited to the formation

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. Collaborative enhancement from Pb(2+) and F(-) in Pb2(NO3)2(H2O)F2 generates the largest second harmonic generation effect among nitrates.

    PubMed

    Peng, Guang; Yang, Yi; Tang, Yu-Huan; Luo, Min; Yan, Tao; Zhou, Yuqiao; Lin, Chensheng; Lin, Zheshuai; Ye, Ning

    2017-08-22

    The first metal nitrate fluoride nonlinear optical material, Pb2(NO3)2(H2O)F2, was synthesized with the largest second harmonic generation (SHG) effect (12 × KH2PO4) among nitrates. Theoretical calculations revealed the synergistic effect of [NO3](-), lone pair electrons in Pb(2+), and F(-) for the SHG effect. The F(-) also promoted the blue-shift of the ultraviolet cut-off edge.

  13. 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)

  14. Synthesis, DFT calculations of structure, vibrational and thermal decomposition studies of the metal complex Pb[Mn(C3H2O4)2(H2O)2].

    PubMed

    Gil, Diego M; Carbonio, Raúl E; Gómez, María Inés

    2015-04-15

    The metallo-organic complex Pb[Mn(C3H2O4)2(H2O)2] was synthesized and characterized by IR and Raman spectroscopy and powder X-ray diffraction methods. The cell parameters for the complex were determined from powder X-ray diffraction using the autoindexing program TREOR, and refined by the Le Bail method with the Fullprof program. A hexagonal unit cell was determined with a=b=13.8366(7)Å, c=9.1454(1)Å, γ=120°. The DFT calculated geometry of the complex anion [Mn(C3H2O4)2(H2O)2](2-) is very close to the experimental data reported for similar systems. The IR and Raman spectra and the thermal analysis of the complex indicate that only one type of water molecules is present in the structure. The thermal decomposition of Pb[Mn(C3H2O4)2(H2O)2] at 700 °C in air produces PbO and Pb2MnO4 as final products. The crystal structure of the mixed oxide is very similar to that reported for Pb3O4. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Synthesis, Structure, Properties And Biological Behaviour Of The Complex [RuIV (H2L) Cl2].2H2O (H4L= 1,2-Cyclohexanediamminetetraacetic Acid)

    PubMed Central

    Vilaplana, Rosario A.; Castiñeiras, A.

    2004-01-01

    The highly water-soluble ruthenium complex [Ru(H2L)Cl2]2H2o, in which H4L is the sequestering ligand trans-l, 2-cyclohexanediamminetetraacetic acid (cdta) has been synthesized, structurally characterized and its properties studied. The X-ray crystallographic study shows that the chelating coordinated ligand is tetradentate while the ruthenium environment is octahedral and slightly distorted, with two chloride anions coordinated in cis positions. Potentiometric, conductimetric and infrared studies confirm the presence of two free carboxylic groups, while electronic and voltammetric studies show that the central ion is Ru(IV). The testing of the cytotoxic activity of this complex against three different human cancer cell lines indicates that [Ru(H2L)Cl2].2H2O shows a remarkable and selective antiproliferative effect against the human uterine neck carcinoma HeLa and the malign adenocarcinoma ADLD, showing only a discrete turnout cell inhibition activity against colon adenocarcinoma HT-29. The important antiprotiferative behaviour of complex 1 against the human adenocarcinoma ADLD, indicates that [Ru(H2L)Cl2].2H2O might be considered as potential antineoplastic compound. PMID:18365080

  16. Apparent or real water exchange reactions on [Zn(H2O)4(L)](2+)·2H2O (L = sp-nitrogen donor ligands)? A quantum chemical investigation.

    PubMed

    Alzoubi, Basam M; Walther, Markus; Puchta, Ralph; van Eldik, Rudi

    2012-06-21

    The exchange of a second coordination sphere water molecule in [Zn(H(2)O)(4)(L)](2+)·2H(2)O (L = HN(3), HCN, FCN, ClCN, BrCN, CH(3)CN, (C(4)H(3))CN, PhCN, (CH(3))(3)CCN, CF(3)CN, CCl(3)CN, CHCl(2)CN, and CH(2)ClCN) against a coordinated water molecule was studied by quantum chemical calculations (RB3LYP/6-311+G**). The complete reaction consists of an associative binding of one H(2)O from the second coordination sphere leading to a six-coordinate intermediate [Zn(H(2)O)(5)(L)](2+)·H(2)O, followed by the dissociation of a water molecule to reach the product state [Zn(H(2)O)(4)(L)](2+)·2H(2)O. For a real water exchange reaction to occur two different transition states have to be included, otherwise only an apparent water exchange reaction takes place. For the water exchange reaction in [Zn(H(2)O)(4)(L)](2+)·2H(2)O, nearly iso-energetic cis- and trans-orientated transition states are crossed. The gas-phase proton affinity of L shows instructive correlations with structural parameters and energy gaps for the investigated reactions.

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  18. First solid state alkaline-earth complexes of monensic acid A (MonH): crystal structure of [M(Mon)2(H (2)O)2] (M = Mg, Ca), spectral properties and cytotoxicity against aerobic Gram-positive bacteria.

    PubMed

    Pantcheva, Ivayla N; Zhorova, Rumyana; Mitewa, Mariana; Simova, Svetlana; Mayer-Figge, Heike; Sheldrick, William S

    2010-02-01

    Alkaline-earth metal complexes of the monoanionic form of the polyether ionophore monensin A were isolated for the first time in solid state and were structurally characterized using various spectroscopic methods (IR, NMR, FAB-MS). The stoichiometric reaction of monensic acid (MonH) with M(2+) (M = Mg, Ca) in the presence of an organic base leads to the formation of mononuclear complexes of composition [M(Mon)(2)(H(2)O)(2)]. The structures of magnesium (1) and calcium (2) monensin complexes in the solid state were established by single crystal X-ray crystallography. The complexes crystallize as [Mg(Mon)(2)(H(2)O)(2)]x5MeCN (1) and [Ca(Mon)(2)(H(2)O)(2)]xH(2)Ox5MeCN (2) in the monoclinic P21 space group. The alkaline-earth metal ion is placed in a distorted octahedral environment, defined by two monensin anions acting as bidentate ligands in the equatorial plane of the complex as well as by two water molecules occupying the axial positions of the inner coordination sphere. The bactericidal activity of 1 and 2 was evaluated against aerobic Gram-positive microorganisms applying the double layer agar hole diffusion method.

  19. 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.

  20. 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

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

    PubMed

    Nguyen, Sau Doan; Halasyamani, P Shiv

    2013-03-04

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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Electrochemically-induced TCNQ/Mn[TCNQ]2(H2O)2 (TCNQ = 7,7,8,8-tetracyanoquinodimethane) solid-solid interconversion: two voltammetrically distinct processes that allow selective generation of nanofiber or nanorod network morphologies.

    PubMed

    Nafady, Ayman; Bond, Alan M; O'Mullane, Anthony P

    2009-10-05

    Unlike the case with other divalent transition metal M[TCNQ](2)(H(2)O)(2) (M = Fe, Co, Ni) analogues, the electrochemically induced solid-solid phase interconversion of TCNQ microcrystals (TCNQ = 7,7,8,8-tetracyanoquinodimethane) to Mn[TCNQ](2)(H(2)O)(2) occurs via two voltammetrically distinct, time dependent processes that generate the coordination polymer in nanofiber or rod-like morphologies. Careful manipulation of the voltammetric scan rate, electrolysis time, Mn(2+)((aq)) concentration, and the method of electrode modification with solid TCNQ allows selective generation of either morphology. Detailed ex situ spectroscopic (IR, Raman), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) characterization clearly establish that differences in the electrochemically synthesized Mn-TCNQ material are confined to morphology. Generation of the nanofiber form is proposed to take place rapidly via formation and reduction of a Mn-stabilized anionic dimer intermediate, [(Mn(2+))(TCNQ-TCNQ)(2)(*-)], formed as a result of radical-substrate coupling between TCNQ(*-) and neutral TCNQ, accompanied by ingress of Mn(2+) ions from the aqueous solution at the triple phase TCNQ/electrode/electrolyte boundary. In contrast, formation of the nanorod form is much slower and is postulated to arise from disproportionation of the [(Mn(2+))(TCNQ-TCNQ)(*-)(2)] intermediate. Thus, identification of the time dependent pathways via the solid-solid state electrochemical approach allows the crystal size of the Mn[TCNQ](2)(H(2)O)(2) material to be tuned and provides new mechanistic insights into the formation of different morphologies.

  7. 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)

  8. Metal phosphonates based on aminomethylenediphosphonate: Syntheses and characterization of Na 4Zn{NH 3CH(PO 3) 2} 2·4H 2O, Ni{NH 3CH(PO 3H) 2} 2· xH 2O and NaNi 2{NH 3CH(PO 3)(PO 3H 0.5)} 2(H 2O) 2·2H 2O

    NASA Astrophysics Data System (ADS)

    Bao, Song-Song; Wang, Tian-Wei; Li, Yi-Zhi; Zheng, Li-Min

    2006-02-01

    This paper describes the syntheses of three transition metal diphosphonate compounds: Na 4Zn{NH 3CH(PO 3) 2} 2·4H 2O ( 1), Ni{NH 3CH(PO 3H) 2} 2· xH 2O ( 2) and NaNi 2{NH 3CH(PO 3)(PO 3H 0.5)} 2(H 2O) 2·2H 2O ( 3). Compound 1 contains chains of [Zn{NHCH(PO)2}2]n4n- made up of corner-sharing ZnO 6 octahedra and CPO 3 tetrahedra, which are further connected by tetramers of edge-sharing NaO 6 octahedra, forming a three-dimensional open-framework structure. Compound 2 shows a square-grid layer structure where the NiO 6 octahedra are corner shared with CPO 3 tetrahedra. The adjacent layers are linked by strong inter-layer hydrogen bonds, resulting in a three-dimensional open-network structure with channels where the lattice water molecules reside. The structure of compound 3 is analogous to that of NaCo 2{NH 3CH(PO 3)(PO 3H 0.5)} 2(H 2O) 2· xH 2O in which layers of Ni 2{NH 3CH(PO 3)(PO 3H 0.5)} 2(H 2O) 2 are connected by NaO 6 linkages into an open-framework structure. The magnetic studies show that weak antiferromagnetic interactions are mediated between the nickel ions in compounds 2 and 3. Crystal data for 1: triclinic, space group P-1, a=5.551(2) Å, b=6.166(2) Å, c=12.424(4) Å, α=92.422(6)°, β=92.687(7)°, γ=93.926(6)°, V=423.3(2) Å3, Z=2. For 2: triclinic, space group P-1, a=9.043(1) Å, b=9.180(1) Å, c=9.271(1) Å, α=89.693(3)°, β=70.202(3)°, γ=89.530(3)°, V=724.1(2) Å3, Z=2.

  9. Theoretical characterization of the reaction CH3 + OH yields CH3OH yields 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.

  10. 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.

  11. 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.

  12. 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.

  13. Structures, physicochemical and cytoprotective properties of new oxidovanadium(IV) complexes -[VO(mIDA)(dmbipy)]·1.5H2O and [VO(IDA)(dmbipy)]·2H2O

    NASA Astrophysics Data System (ADS)

    Drzeżdżon, Joanna; Jacewicz, Dagmara; Wyrzykowski, Dariusz; Inkielewicz-Stępniak, Iwona; Sikorski, Artur; Tesmar, Aleksandra; Chmurzyński, Lech

    2017-09-01

    New oxidovanadium(IV) complexes with a modification of the ligand in the VO2+ coordination sphere were synthesized. [VO(mIDA)(dmbipy)]•1.5H2O and [VO(IDA)(dmbipy)]•2H2O were obtained as dark green crystals and grey-green powder, respectively (mIDA = N-methyliminodiacetic anion, IDA = iminodiacetic anion, dmbipy = 4,4‧-dimethoxy-2,2‧-dipyridyl). The crystal structure of [VO(mIDA)(dmbipy)]·1.5H2O has been determined by the X-ray diffraction method. The studies of structure of [VO(mIDA)(dmbipy)]•1.5H2O have shown that this compound occurs in the crystal as two rotational conformers. Furthermore, the stability constants of [VO(mIDA)(dmbipy)]•1.5H2O and [VO(IDA)(dmbipy)]•2H2O complexes in aqueous solutions were studied by using the potentiometric titration method and, consequently, determined using the Hyperquad2008 program. Moreover, the title complexes were investigated as antioxidant substances. The impact of the structure modification in the VO2+ complexes on the radical scavenging activity has been studied. The ability to scavenge the superoxide radical by two complexes - [VO(mIDA)(dmbipy)]·1.5H2O and [VO(IDA)(dmbipy)]·2H2O was studied by cyclic voltammetry (CV) and nitrobluetetrazolium (NBT) methods. The title complexes were also examined by the spectrophotometric method as scavengers of neutral organic radical - 1,1-diphenyl-2-picrylhydrazyl (DPPH•) and radical cation - 2,2'-azinobis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS•+). Furthermore, the biological properties of two oxidovanadium(IV) complexes were investigated in relation to its cytoprotective properties by the MTT and LDH tests based on the hippocampal HT22 neuronal cell line during the oxidative damage induced by hydrogen peroxide. Finally, the results presented in this paper have shown that the both new oxidovanadium(IV) complexes with the 4,4‧-dimethoxy-2,2‧-dipyridyl ligand can be treated as the cytoprotective substances.

  14. 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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  17. Mass spectrometric investigations of plasma chemical reactions in a radiofrequency discharge with Ar/C2H2 and Ar/C2H2/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Herrendorf, Ann-Pierra; Sushkov, Vladimir; Hippler, Rainer

    2017-03-01

    Plasma chemical reactions in complex Ar/C2H2 and Ar/C2H2/O2 radiofrequency plasmas with formation of nano-particles are investigated. Growing nano-particles cause a growth instability, which leads to temporal variations and a cyclic behaviour of plasma properties. Mass spectrometric observations show the consumption of C2H2 and the formation of polyacetylene C2nH2 molecules which increases with acetylene gas flow. The cycle frequency is a decreasing function of acetylene consumption. The addition of oxygen to the discharge reduces the cycle frequency and the formation of nano-particles and leads to the formation of CO and CO2 molecules presumably through the oxidation of C2H radicals which are formed in the discharge.

  18. 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.

  19. Synthesis, Single Crystal Structure, and Magnetic Properties of 3-D Cu(NITpPy)2[Cu(CN)3].2CH3OH.2H2O Complexes

    NASA Astrophysics Data System (ADS)

    Dasna, I. W.; Golhen, S.; Ouahab, L.; Subakti

    2017-05-01

    A new Cu(II) complexes containing nitroxide radicals Cu(NITpPy)2[Cu(CN)3]. 2CH3OH.2H2O has been successfully synthesized. The single crystal X-ray analysis revealed that the compound belongs to monoclinic crystal system (C2/c (#15)). The existence of the C≡N radical and water molecules are observed by using infra-red within the range of 4000-500 cm-1 and 3500-3000 cm-1, respectively. The Cu(NITpPy)2 2+ units are connected through N(CN)2- bridging ligands in 2 coordination developing, respectively, into one-dimensional and two-dimensional polymeric networks. Paramagnetic interactions in the compound appear in the vicinity of room temperature. As the temperature decreased, low dimensional antiferromagnetic interactions established and Cu(II)-radicals antiferromagnetic interactions dominates down to 2 K with μeff = 0.8129 μB

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. A kinetic study of the CH2OO Criegee intermediate reaction with SO2, (H2O)2, CH2I2 and I atoms using OH laser induced fluorescence.

    PubMed

    Liu, Yiqiang; Liu, Fenghua; Liu, Siyue; Dai, Dongxu; Dong, Wenrui; Yang, Xueming

    2017-08-09

    The OH laser induced fluorescence method was used to study the kinetics of CH2OO reacting with SO2, (H2O)2, CH2I2 and I atoms. Decay of CH2OO is not strictly first-order since its self-reaction is rapid. With this consideration, we derived the rate coefficient of CH2OO + SO2/(H2O)2/CH2I2/I taking into account the contribution of the CH2OO self-reaction. For the CH2OO + SO2 reaction, the rate coefficient is measured to be (3.88 ± 0.13) × 10(-11) cm(3) molecule(-1) s(-1) at 10 Torr, which agrees very well with a previously reported value obtained by directly monitoring CH2OO using the UV absorption method with the CH2OO self-reaction considered. We did not observe obvious evidence for SO2 catalysed CH2OO isomerization or the intersystem crossing effect in this reaction. CH2OO + (H2O)2 is supposed to account for the major sink of CH2OO in the atmosphere, but previous rate coefficient measurements were not in good agreement. We have revisited this reaction including the self-reaction of CH2OO and obtained the rate coefficient to be (7.53 ± 0.38) × 10(-12) cm(3) molecule(-1) s(-1) at 60 Torr and 300 K. The rate coefficients of CH2OO + CH2I2 and CH2OO + I were measured to be (5.2 ± 2.6) × 10(-14) and (2.2 ± 1.1) × 10(-12) cm(3) molecule(-1) s(-1) respectively.

  7. 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).

  8. Metal carbonate complexes formed through the capture of ambient O2 and CO2 by elemental metals in 1-methylimidazole: molecular Cu(CO3)(MeIm)3 and polymeric M(CO3)(MeIm)2·2H2O (M = Co, Zn).

    PubMed

    Vaid, Thomas P; Kelley, Steven P; Rogers, Robin D

    2017-07-18

    When immersed in 1-methylimidazole, the metals copper, zinc, and cobalt will react with ambient dioxygen and carbon dioxide to yield the blue-green molecular complex Cu(CO3)(MeIm)3 and the pair of isostructural polymeric complexes Zn(CO3)(MeIm)2·2H2O and Co(CO3)(MeIm)2·2H2O, respectively.

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

    NASA Astrophysics Data System (ADS)

    Uchikawa, Joji; Zeebe, Richard E.

    2012-10-01

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

  10. 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

  11. Theoretical Modeling of Water Exchange on [Pd(H(2)O)(4)](2+), [Pt(H(2)O)(4)](2+), and trans-[PtCl(2)(H(2)O)(2)].

    PubMed

    Deeth, Robert J.; Elding, Lars I.

    1996-08-14

    Density functional theory is applied to modeling the exchange in aqueous solution of H(2)O on [Pd(H(2)O)(4)](2+), [Pt(H(2)O)(4)](2+), and trans-[PtCl(2)(H(2)O)(2)]. Optimized structures for the starting molecules are reported together with trigonal bipyramidal (tbp) systems relevant to an associative mechanism. While a rigorous tbp geometry cannot by symmetry be the actual transition state, it appears that the energy differences between model tbp structures and the actual transition states are small. Ground state geometries calculated via the local density approximation (LDA) for [Pd(H(2)O)(4)](2+) and relativistically corrected LDA for the Pt complexes are in good agreement with available experimental data. Nonlocal gradient corrections to the LDA lead to relatively inferior structures. The computed structures for analogous Pd and Pt species are very similar. The equatorial M-OH(2) bonds of all the LDA-optimized tbp structures are predicted to expand by 0.25-0.30 Å, while the axial bonds change little relative to the planar precursors. This bond stretching in the transition state counteracts the decrease in partial molar volume caused by coordination of the entering water molecule and can explain qualitatively the small and closely similar volumes of activation observed. The relatively higher activation enthalpies of the Pt species can be traced to the relativistic correction of the total energies while the absolute DeltaH() values for exchange on [Pd(H(2)O)(4)](2+) and [Pt(H(2)O)(4)](2+) are reproduced using relativistically corrected LDA energies and a simple Born model for hydration. The validity of the latter is confirmed via some simple atomistic molecular mechanics estimates of the relative hydration enthalpies of [Pd(H(2)O)(4)](2+) and [Pd(H(2)O)(5)](2+). The computed DeltaH() values are 57, 92, and 103 kJ/mol compared to experimental values of 50(2), 90(2), and 100(2) kJ/mol for [Pd(H(2)O)(4)](2+), [Pt(H(2)O)(4)](2+), and trans-[PtCl(2)(H(2)O)(2

  12. Crystallization Experiments in the MgO-CO2-H2O system: Role of Amorphous Magnesium Carbonate Precursors in Magnesium Carbonate Hydrated Phases and Morphologies in Low Temperature Hydrothermal Fluids

    NASA Astrophysics Data System (ADS)

    Giampouras, Manolis; Garcia-Ruiz, Juan Manuel; Garrido, Carlos J.

    2017-04-01

    Numerous forms of hydrated or basic magnesium carbonates occur in the complex MgO-CO2-H2O system. Mineral saturation states from low temperature hydrothermal fluids in Semail Ophiolite (Oman), Prony Bay (New Caledonia) and Lost City hydrothermal field (mid-Atlantic ridge) strongly indicate the presence of magnesium hydroxy-carbonate hydrates (e.g. hydromagnesite) and magnesium hydroxides (brucite). Study of formation mechanisms and morphological features of minerals forming in the MgO-CO2-H2O system could give insights into serpentinization-driven, hydrothermal, alkaline environments, which are related to early Earth conditions. Temperature, hydration degree, pH and fluid composition are crucial factors regarding the formation, coexistence and transformation of such mineral phases. The rate of supersaturation, on the other hand, is a fundamental parameter to understand nucleation and crystal growth processes. All these parameters can be examined in a solution using different crystallization techniques. In the present study, we applied different crystallization techniques to synthesize and monitor the crystallization of Mg-bearing carbonates and hydroxides under abiotic conditions. Various crystallization techniques (counter-diffusion, vapor diffusion and unseeded solution mixing) were used to screen the formation conditions of each phase, transformation processes and structural development. Mineral and textural characterization of the different synthesized phases were carried out by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy coupled to dispersive energy spectroscopy (FE-SEM-EDS). Experimental investigation of the effect of pH level and silica content under variable reactant concentrations revealed the importance of Amorphous Magnesium Carbonate (AMC) in the formation of hydroxy-carbonate phases (hydromagnesite and dypingite). Micro-structural resemblance between AMC precursors and later stage crystalline phases highlights the

  13. Synthesis and characterization of the open-framework barium bisphosphonate [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O.

    PubMed

    Bauer, Sebastian; Müller, Helen; Bein, Thomas; Stock, Norbert

    2005-12-12

    Following the strategy of using polyfunctional phosphonic acids for the synthesis of open-framework metal phosphonates, the phosphonocarboxylic acid (H2O3PCH2)2NCH2C6H4COOH was used in the hydrothermal synthesis of new Ba phosphonates. Its decomposition led to the first open-framework barium phosphonate [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O. The synthesis was also successfully performed using iminobis(methylphosphonic acid), (H2O3PCH2)2NH, as a starting material, and the synthesis was optimized to obtain as a pure material. The reaction setup as well as the pH are the dominant parameters, and only a diffusion-controlled reaction led to the desired compound. The crystal structure was solved from single-crystal data: monoclinic; C2/c; a=2328.7(2), b=1359.95(7), and c=718.62(6) pm; beta=98.732(10) degrees ; V=2249.5(3)x10(6) pm3; Z=4; R1=0.036; and wR2=0.072 (all data). The structure of [Ba3(O3PCH2NH2CH2PO3)2(H2O)4].3H2O is built up from BaO8 and BaO10 polyhedra forming BaO chains and layers, respectively. These are connected to a three-dimensional metal-oxygen-metal framework with the iminobis(methylphosphonic acid) formally coating the inner walls of the pores. The one-dimensional pores (3.6x4 A) are filled with H2O molecules that can be thermally removed. Thermogravimetric investigations and temperature-dependent X-ray powder diffraction demonstrate the stability of the crystal structure up to 240 degrees C. The uptake of N,N-dimethylformamide and H2O by dehydrated samples is demonstrated. Furthermore, IR, Raman, and 31P magic-angle-spinning NMR data are also presented.

  14. 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.

  15. Magnetism of CuCl2·2D2O and CuCl2·2H2O, and of CuBr2·6H2O

    NASA Astrophysics Data System (ADS)

    DeFotis, G. C.; Hampton, A. S.; Van Dongen, M. J.; Komatsu, C. H.; Benday, N. S.; Davis, C. M.; Hays, K.; Wagner, M. J.

    2017-07-01

    The magnetic properties of little examined CuCl2·2D2O are studied and compared with those of CuCl2·2H2O. New CuBr2·6H2O is also examined. Susceptibility maxima appear for chlorides at 5.35 and 5.50 K, in the above order, with estimated antiferromagnetic ordering at 4.15 and 4.25 K. Curie-Weiss fits yield g of 2.210 and 2.205, and Weiss θ of -6.0 and -4.7 K, respectively, in χM = C/(T - θ). One-dimensional Heisenberg model fits to susceptibilities, including interchain exchange in a mean-field approximation, are performed. Interchain exchange is significant but much weaker than intrachain. The bromide hexahydrate strongly differs magnetically from any chloride hydrate, but exhibits notable similarities and differences compared to previously studied CuBr2. A broad susceptibility maximum occurs near 218 K, only 4% lower than for CuBr2, but with almost twice the magnitude. Powder X-ray diffraction data for CuBr2·6H2O may be best accounted for by a monoclinic unit cell that is metrically orthorhombic. The volume per formula unit is consistent with trends in metal ionic radii. However, an alternative monoclinic cell with 5% smaller volume more readily rationalizes the magnetism.

  16. A novel two-dimensional β-octamolybdate supported alkaline-earth metal complex: [Ba(DMF) 2(H 2O)] 2[Mo 8O 26]·2DMF

    NASA Astrophysics Data System (ADS)

    Qin, Chao; Wang, Xinlong; Qi, Yanfei; Wang, Enbo; Hu, Changwen; Xu, Lin

    2004-10-01

    A novel β-octamolybdate supported complex [Ba(DMF)2(H2O)]2[Mo8O26]·2DMF (1) was synthesized by the direct modification to the surface of octamolybdate molecular cluster. Its structure was determined by elemental analysis, TG analysis, IR spectrum, and the single-crystal X-ray diffraction. The title compound crystallizes in triclinic system, space group P1¯, a=9.984(2) Å, b=11.117(2) Å, c=12.681(3) Å, α=115.86(3)°, β=97.66(3)°, γ=98.11(3)°, V=1223.5(4) Å3, Z=2, λ(MoKα)=0.71073 Å, (R(F)=0.0386 for 5535 reflections). Data were collected on a Rigaku R-AXIS RAPID IP diffractometer at 293 K in the range of 2.04<θ<27.47°. Compound 1 exhibits a novel two-dimensional (2D) layered framework in which all β-[Mo8O26]4- subunits are connected together through Ba-O-Ba-O-Mo and Ba-O-Mo bridges. Furthermore, these 2D layers are extended into 3D supramolecular network containing parallelogram channels via hydrogen-bonding interactions.

  17. 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.

  18. 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.

  19. Exogenous application of poly-γ-glutamic acid enhances stress defense in Brassica napus L. seedlings by inducing cross-talks between Ca(2+), H2O2, brassinolide, and jasmonic acid in leaves.

    PubMed

    Xu, Zongqi; Lei, Peng; Pang, Xiao; Li, Huashan; Feng, Xiaohai; Xu, Hong

    2017-09-01

    Poly-γ-glutamic acid (γ-PGA) is a microbe-secreted isopeptide shown to promote growth and enhance crop stress tolerance. However, its downstream signaling pathways are unknown. Here, we studied γ-PGA-induced tolerance to salt and cold stresses. Pretreatment with γ-PGA contributed to enhance stress tolerance of canola seedlings by promoting proline accumulation and total antioxidant capacity (T-AOC) improvement. Further, Ca(2+), H2O2, brassinolide, and jasmonic acid were found to be involved in the γ-PGA-induced process. First, using signal blockers, we concluded that γ-PGA activated Ca(2+) fluctuations in canola seedling leaves. Second, the activated Ca(2+) further elicited H2O2 production by Ca(2+)-binding proteins CBL9, CPK4, and CPK5. Third, the H2O2 signal promoted brassinolide and jasmonic acid biosynthesis by upregulating key genes (DWF4 and LOX2, respectively) for synthesizing these compounds. Lastly, brassinolide and jasmonic acid increased H2O2 which promoted proline accumulation and T-AOC improvement and further enhanced Ca(2+)-binding proteins including CaM, CBL10, and CPK9. Copyright © 2017. Published by Elsevier Masson SAS.

  20. 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.

  1. 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.

  2. Facile and Scalable Synthesis of Zn3V2O7(OH)2·2H2O Microflowers as a High-Performance Anode for Lithium-Ion Batteries.

    PubMed

    Yan, Haowu; Luo, Yanzhu; Xu, Xu; He, Liang; Tan, Jian; Li, Zhaohuai; Hong, Xufeng; He, Pan; Mai, Liqiang

    2017-08-23

    The employment of nanomaterials and nanotechnologies has been widely acknowledged as an effective strategy to enhance the electrochemical performance of lithium-ion batteries (LIBs). However, how to produce nanomaterials effectively on a large scale remains a challenge. Here, the highly crystallized Zn3V2O7(OH)2·2H2O is synthesized through a simple liquid phase method at room temperature in a large scale, which is easily realized in industry. Through suppressing the reaction dynamics with ethylene glycol, a uniform morphology of microflowers is obtained. Owing to the multiple reaction mechanisms (insertion, conversion, and alloying) during Li insertion/extraction, the prepared electrode delivers a remarkable specific capacity of 1287 mA h g(-1) at 0.2 A g(-1) after 120 cycles. In addition, a high capacity of 298 mA h g(-1) can be obtained at 5 A g(-1) after 1400 cycles. The excellent electrochemical performance can be attributed to the high crystallinity and large specific surface area of active materials. The smaller particles after cycling could facilitate the lithium-ion transport and provide more reaction sites. The facile and scalable synthesis process and excellent electrochemical performance make this material a highly promising anode for the commercial LIBs.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. 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.

  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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Comparative study on the anticancer activities and binding properties of a hetero metal binuclear complex [Co(dipic)2Ni(OH2)5]·2H2O (dipic=dipicolinate) with two carrier proteins.

    PubMed

    Shahraki, Somaye; Shiri, Fereshteh; Majd, Mostafa Heidari; Razmara, Zohreh

    2017-10-25

    Recognizing of binding mechanisms between drugs and carrier proteins is basic for us to understand the pharmacokinetics and pharmacodynamics of them. In this research, the anticancer activities of a binuclear complex [Co(dipic)2Ni(OH2)5]·2H2O (dipic=dipicolinate) against MDA-MB-231 cell lines were studied. Results of MTT assay and flow cytometry analysis revealed that above complex can induce the cytotoxicity and the apoptosis in breast cancer cell lines. So, this complex was selected to investigate its binding to human serum albumin (HSA) and bovine β-lactoglobulin (βLG) by spectroscopic methods (UV-visible, fluorescence and FT-IR) along with molecular docking technique. The fluorescence data showed Co-Ni complex quench the fluorescence of both proteins by a static quenching mechanism and HSA has stronger binding affinity toward Co-Ni complex than βLG. The binding constant (Kb), number of binding sites (n) and thermodynamic parameters were calculated and showed that the Co-Ni complex binds to protein (HSA and βLG) through hydrogen bonding and van der Waals forces with one binding site. The results of UV-visible measurements indicated that the binding of above complex to HSA and βLG may induce conformational and micro-environmental changes of studied proteins. Protein-ligand docking analysis confirmed that the Co-Ni complex binds to residues located in the subdomain IIA of HSA and site II of βLG. Copyright © 2017. Published by Elsevier B.V.

  15. 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.

  16. 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

  17. 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

  18. Two-component, ab initio potential energy surface for CO2—H2O, extension to the hydrate clathrate, CO2@(H2O)20, and VSCF/VCI vibrational analyses of both

    NASA Astrophysics Data System (ADS)

    Wang, Qingfeng Kee; Bowman, Joel M.

    2017-10-01

    We report an ab initio, full-dimensional, potential energy surface (PES) for CO2—H2O, in which two-body interaction energies are fit using a basis of permutationally invariant polynomials and combined with accurate potentials for the non-interacting monomers. This approach which we have termed "plug and play" is extended here to improve the precision of the 2-body fit in the long range. This is done by combining two separate fits. One is a fit to 47 593 2-body energies in the region of strong interaction and approaching the long range, and the second one is a fit to 6244 2-body energies in the long range. The two fits have a region of overlap which permits a smooth switch from one to the other. All energies are obtained at the CCSD(T)-F12b/aug-cc-pVTZ level of theory. Properties of the full PES, i.e., stationary points, harmonic frequencies of the global minimum, etc., are shown to be in excellent agreement with direct CCSD(T)-F12b/aug-cc-pVTZ results. Diffusion Monte Carlo calculations of the dimer zero-point energy (ZPE) are performed, and a dissociation energy, D0, of 787 cm-1 is obtained using that ZPE, De, and the rigorous ZPEs of the monomers. Using a benchmark De, D0 is 758 cm-1. Vibrational self-consistent field (VSCF)/virtual state configuration interaction (VCI) MULTIMODE calculations of intramolecular fundamentals are reported and are in good agreement with available experimental results. Finally, the full dimer PES is combined with an existing ab initio water potential to develop a potential for the CO2 hydrate clathrate CO2(H2O)20(512 water cage). A full normal-mode analysis of this hydrate clathrate is reported as are local-monomer VSCF/VCI calculations of the fundamentals of CO2.

  19. Short Wave Upwelling Radiative Flux (SWupRF) within Near Infrared (NIR) Wavelength Bands of O2, H2O, CO2, and CH4 by Argus 1000 Along with GENSPECT Line by Line Radiative Transfer Model

    NASA Astrophysics Data System (ADS)

    Siddiqui, Rehan; Jagpal, Rajinder; Quine, Brendan M.

    2017-07-01

    This new study develops an algorithm for Short Wave upwelling Radiative Flux (SWupRF) for the spectral variations within near infrared (NIR) from 1100 to 1700 nm wavelength band based on remote sensing data set of Argus 1000 micro-spectrometer observations. We calculate the SWupRF by investigating the total radiative flux due to O2, H2O, CO2 and CH4 and also by the individual gas within the selected wavelength bands of interest. A GENSPECT synthetic line by line radiative transfer model is applied to perform radiative transfer simulations to calculate the radiative flux by varying surface albedo, mixing ratios of the selected greenhouse gases, surface temperature, solar sun and zenith angles with different latitude and longitude of the instrument. Finally, the SWupRFsyn estimated from GENSPECT was compared with SWupRFobs from Argus 1000 over a period of four years (2009 and 2013) covering all seasons. We calculate and compare both the synthetic and real measured observed data set. The synthetic model gives SWupRFsyn within the range of [0.3950 to 1.650] W/m2 and the selected Argus observed model gives SWupRFobs within the range of [0.10 to 3.15] W/m2. The simulated range of synthetic model also represents 1 to 32 K rise of temperature within the different concentration of water vapor and other gases. The authors determined that the satellite observed data of week 75 pass 43 & week 08 pass 61 showing minimum 0.850 [0.10 to 1.60] W/m2 and maximum 1.65 [0.12 to 3.15] W/m2 respectively.

  20. Formation of refractory ring-expanded triazine intermediates during the photocatalyzed mineralization of the endocrine disruptor amitrole and related triazole derivatives at UV-irradiated TiO2/H2O interfaces.

    PubMed

    Watanabe, Natsuko; Horikoshi, Satoshi; Kawasaki, Atsushi; Hidaka, Hisao; Serpone, Nick

    2005-04-01

    Amitrole (ATz, 3-amino-1H-1,2,4-triazole) is a widely employed herbicide with strong estrogenic activity that can lead to abnormalities of the thyroid gland and can cause mutations. The photocatalytic transformation of ATz was carried out at the UV-irradiated TiO2/H2O interface, along with the triazole derivatives Tz (1H-1,2,4-triazole) and DaTz (3,5-diamino-1H-1,2,4-triazole) to assess the decomposition of these herbicides, to identify intermediates, and to elucidate some mechanistic details of the ATz degradation. Conversion of the nitrogens of these triazoles to NH4+ and/ or NO3- ions occurs competitively and depends on the number of amine functions on the five-membered triazole rings. Photomineralization of the substrates in terms of loss of nitrogen to NH4+/NO3- was rather low (ca. 25-40%) for each of the triazoles, whereas evolution of CO2 (loss of TOC) was more significant (60-70%), indicating considerable retention of nitrogen in the intermediate products. UV-Vis spectroscopy, TOC assays, FT-IR spectroscopy, proton NMR spectrometry, electrospray LC-MS, and molecular orbital calculations were brought to bear in assessing the temporal course of the photocatalyzed process(es). Results show that after cleavage of the triazole ring, the various intermediate fragments recombine to yield ring-expanded six-membered triazine intermediates, which slowly degrade to give the refractory cyanuric acid under the conditions used.

  1. 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.

  2. 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.

  3. 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.

  4. Hydrothermal Synthesis and Crystal Structure of Zn 4(PO 4) 2(HPO 4) 2·0.5(C 10H 28N 4)·2H 2O, a New Layered Zinc Phosphate with 12-Ring Cavities

    NASA Astrophysics Data System (ADS)

    Zhang, Ping; Wang, Yue; Zhu, Guangshan; Shi, Zhan; Liu, Yunling; Yuan, Hongming; Pang, Wenqin

    2000-11-01

    Using 1, 4, 8, 11-tetraazacyclotetradecane (cyclam) as a template, a new layered zinc phosphate Zn4(PO4)2(HPO4)2·0.5(C10H28N4)·2H2O (defined as ZnPO-cyclam) with 12-ring cavities was synthesized under hydrothermal conditions in a molar ratio ZnO:P2O5:cyclam:H2O=1:2.2:0.5:284.7 at 140°C for 3 days. The gel had a pH 4 at the starting period. The ZnPO-cyclam crystal structure is solved using single-crystal X-ray diffraction data at 293 K. It crystallizes in monoclinic space group P21/c (no.14) with lattice parameters a=15.758(3) Å, b=9.0292(15) Å, c=15.543(3) Å, β=111.070 (16). V=2063.7(7) Å3, Z=4, R=0.0392, wR=0.0472, 4166 collected reflections, 2794 observed reflections with I>2σ(I). The structure of ZnPO-cyclam consists of alternating inorganic and organic layers. The inorganic layers are built up from ZnO4, ZnO3(H2O)2, PO4, and HPO4 with Zn-O-Zn and Zn-O-P bonds. The protonated cyclam molecules in which the four nitrogen atoms are all protonated form the organic layers. Strong hydrogen bonding exists between the inorganic-organic layers, and there are 12-ring cavities in the inorganic layers, in which the template cyclam molecules reside.

  5. Nuclear and magnetic structures and magnetic properties of the layered cobalt hydroxysulfate Co5(OH)6(SO4)2(H2O)4 and its deuterated analogue, Co5(OD)6(SO4)2(D2O)4.

    PubMed

    Salah, Mohsen Ben; Vilminot, Serge; André, Gilles; Richard-Plouet, Mireille; Mhiri, Tahar; Takagi, Seishi; Kurmoo, Mohamedally

    2006-06-21

    The structures (nuclear and magnetic), magnetic properties (2-300 K, 1-10(4) bar), and heat capacity of the layered ferromagnet Co5(OH)6(SO4)2(H2O)4 are reported. The crystal structure consists of brucite-like M(II)-OH layers of edge-sharing octahedra, but having two different Co sites, which are pillared by ...O3SO-Co(H2O)4-OSO3.... The absorption spectrum confirms the presence of divalent Co, and by comparison of the two isotopic materials, the assignment of the vibrational spectra is proposed. The magnetic properties are those of a ferromagnet with a Curie temperature of 14 K. Temperature and field dependence magnetization data taken on an aligned sample suggest an easy-plane magnet. The Curie temperature increases linearly with pressure at a rate of +0.12 K/kbar, suggesting small progressive and uniform modifications of the Co-Co exchange interactions. Rietveld refinement of the neutron powder diffraction data and consideration of a group analysis reveal the direction of the moments of the Co within the layer to be along the b-axis, with a maximum moment of 3.33 micro(B) per cobalt. Those of the pillars remain random. Estimation of the entropy from the heat capacity data accounts for the presence of four ordered moments of Co with spin 1/2 at the long-range ordering temperature, while the moment of the pillaring Co contributes only at lower temperature due to the increase of the internal field as the temperature is lowered. The purely 2D-magnetic ordering in an easy-plane magnet, evidenced by neutron diffraction and heat capacity, challenges the existing theories and is a rare example of a single-layer magnet.

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

    PubMed

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

    2016-01-04

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

  7. [Ph(3)PCH(2)Ph](2)[Zn(3)(tp)(3)Cl(2)] and Ni(3)(tma)(2)(H(2)O)(8): two unusual claylike frameworks of metal-polycarboxylate coordination polymers (tp = terephthalate, tma = trimesate).

    PubMed

    Yang, Guo-Dong; Dai, Jing-Cao; Lian, Yun-Xia; Wu, Wen-Shi; Lin, Jian-Ming; Hu, Sheng-Min; Sheng, Tian-Lu; Fu, Zhi-Yong; Wu, Xin-Tao

    2007-09-17

    Two new compounds, [Ph3PCH2Ph]2[Zn3(tp)3Cl2] (1) and Ni3(tma)2(H2O)8 (2) (tp = terephthalate, tma = trimesate), are metal-polycarboxylate coordination polymers prepared by similar hydrothermal synthesis techniques. X-ray single-crystal structural analysis shows that both compounds crystallize in the 2D claylike lamellar architectures, in which 1 possesses the interlayer [Ph3PCH2Ph]+ exchangeable cation and has been confirmed by PXRD patterns. 1 (C74H56Cl2O12P2Zn3) belongs to monoclinic P21/c, Z = 2 (a = 18.956(1) A, b = 10.2697(5) A, c = 17.067(1) A, beta = 99.486(4) degrees ). 2 (C18H22O20Ni3) is attributed to triclinic P, Z = 1 (a = 6.6643(8) A, b = 9.622(1) A, c = 10.089(1) A, alpha = 112.675(2) degrees , beta = 94.007(1) degrees, gamma = 106.411(2) degrees ). Linear metal trinuclear clusters bridged by rigid linear tp ligands for 1 and trigonal tma ligands for 2 give rise to a novel 2D 6-linked (3,6) topological anionic network in 1 and an interesting 2D 3,6-linked molybdenite topological neutral network in 2, respectively. Both compounds exhibit intense fluorescent emission bands at 410 nm (lambda(exc) = 355 nm) for 1 and 398 nm (lambda(exc) = 300 nm) for 2 in the solid state at room temperature.

  8. 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.

  9. Ice-like H2O in hemimorphite, Zn4Si2O7(OH)2H2O: Cp and entropy behavior of confined H2O in microporous silicates

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Dachs, E.

    2009-12-01

    The H2O molecule plays a key role in many planetary processes and, thus, it is necessary to investigate how it interacts with a variety of natural materials. In this regard the role of hydrogen bonding is of central importance, but it has received relatively little study. Certain micro/nanoporous silicates offer the possibility for one to investigate the nature of confined H2O and hydrogen bonding at a relatively simple, yet fundamental level. Hemimorphite, Zn4Si2O7(OH)2.H2O, and its dehydrated analog Zn4Si2O7(OH)2 were studied by low-temperature relaxation microcalorimetry and their heat capacity determined to analyze the behavior of the confined H2O between 5 and 300 K. An analysis of the data, which are corrected for the presence of a phase transition, shows that the Cp of H2O in hemimorphite behaves more similar to the Cp of ice than to liquid water or steam. The H2O molecule, with its four planar hydrogen bonds in hemimorphite, as well as its tetrahedral coordination in ice, is more rigidly hydrogen bonded in both than in liquid water. This is reflected in their respective Cp behavior. The heat capacity and entropy for the dehydration reaction at 298 K are ΔCprxn = -2.1 ± 3.6 J/molK and ΔSrxn = 134.7 ± 4.0 J/molK. Cp behavior at 0 K < T < 300 K and entropy values at 298 K for confined H2O in various microporous silicates were analyzed. The entropy for confined H2O in hemimorphite, and the two zeolites analcime, and mordenite is approximately 54 J/molK at 298 K, while that for cordierite is considerably larger. The strength of the interactions (e.g., H bonding) between a H2O molecule and its surroundings increases approximately from steam > cordierite > analcime > hemimorphite ≥ mordenite > heulandite > natrolite ≈ scolecite > liquid H2O > ice and, in the case of microporous silicates, is inversely proportional to the S of the confined H2O.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. The topotactic dehydration of monoclinic {[Co(pht)(bpy)(H2O)2]·2H2O}n into orthorhombic [Co(pht)(bpy)(H2O)2]n (pht is phthalate and bpy is 4,4'-bipyridine).

    PubMed

    Harvey, Miguel Angel; Suarez, Sebastián; Cukiernik, Fabio D; Baggio, Ricardo

    2014-10-01

    Controlled heating of single crystals of the previously reported [Köferstein & Robl (2007). Z. Anorg. Allg. Chem. 633, 1127-1130] dihydrate {[Co(pht)(bpy)(H2O)2]·2H2O}n, (II) [where pht is phthalate (C8H4O4) and bpy is 4,4'-bipyridine (C10H8N2)], produced a topotactic transformation into an unreported diaqua anhydrate, namely poly[diaqua(μ2-benzene-1,2-dicarboxylato-κ(2)O(1):O(2))(μ2-4,4'-bipyridine-κ(2)N:N')cobalt(II)], [Co(C8H4O4)(C10H8N2)(H2O)2]n, (IIa). The structural change consists of the loss of the two solvent water molecules linking the original two-dimensional covalent substructures which are the `main frame' of the monoclinic P2/n hydrate (strictly preserved during the transformation), with further reaccommodation of the latter. The anhydrate organizes itself in the orthorhombic system (space group Pmn2(1)) in a disordered fashion, where the space-group-symmetry restrictions are achieved only in a statistical sense, with mirror-related two-dimensional planar substructures, mirrored in a plane perpendicular to [100]. Thus, the asymmetric unit in the refined model is composed of two superimposed mirror-related `ghosts' of half-occupancy each. Similarities and differences with the parent dihydrate and some other related structures in the literature are discussed.

  4. Synthesis and characterization of new two-dimensional molybdenum(V) phosphates: (Hen) 6[ M2(H 2O)Mo 12O 24(OH) 6(H 2PO 4) 3(HPO 4) 4(PO 4)]·4H 2O ( M = K, Na)

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Zhong; Lin, Bi-Zhou; He, Li-Wen; Huang, Xiu-Feng; Chen, Yi-Lin

    2008-04-01

    Two new reduced molybdenum(V) phosphates, (Hen) 6[K 2(H 2O)Mo 12O 24(OH) 6(H 2PO 4) 3(HPO 4) 4(PO 4)]·4H 2O and (Hen) 6[Na 2(H 2O)Mo 12O 24(OH) 6(H 2PO 4) 3(HPO 4) 4(PO 4)]·4H 2O (en = ethylenediamine) have been prepared under hydrothermal conditions and characterized by elemental analyses, IR and single-crystal X-ray diffraction. It was revealed that the sandwich-shaped units [ M(Mo 6P 4) 2] are linked by additional octahedrally-coordinated K or Na atoms into two-dimensional layers. The ethylenediamine cations and the lattice water molecules are nestled in the spaces between layers, and are interacted with the inorganic networks through hydrogen bonds into a three-dimensional supramolecular framework. It was indicated that the compounds exhibit photocatalytic activity in the degradation of rhodamine B.

  5. 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.

  6. Hybrid Open-frameworks: structure determinations and ferromagnetism of MIL-41 or (V(IV)O) 2M(II)(H 2O) 4{HO 3PCH 2PO 3} 2 · 2H 2O (M=Mn, Co, Ni, Zn): four mixed metallomethylendiphosphonates hydrothermally synthesized by using pre-assembled building units

    NASA Astrophysics Data System (ADS)

    Barthelet, Karin; Jouve, Cyril; Riou, Didier; Férey, Gérard

    2000-12-01

    MIL-41 or (V(IV)O) 2M(II)(H 2O) 4{HO 3PCH 2PO 3} 2 · 2H 2O was hydrothermally synthesized at 443 K with M(II)=Mn, Co, Ni, Zn. The structures of the four compounds were solved by single crystal X-ray diffraction in the noncentrosymmetric orthorhombic space group Fdd2 (no. 43). The lattice parameters of the Mn compound are a=22.0237(3) Å, b=22.3722(4) Å, c=7.2962(2) Å, V=3595.0(1) Å 3, Z=8 and the reliability factors R1=0.0352, w R2=0.0840 for 2142 reflections with I≥2 σ( I). The structure of MIL-41 is two-dimensional (2-D) with layers built from mixed vanadomethylendiphosphonate chains linked by MO 2(H 2O) 4 octahedra. These solids are ferromagnetic below 5 K due to dipolar interactions.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Ferromagnetic Coupling between Copper(II) Centers through the Diamagnetic Zinc(II) Ion: Crystal Structure and Magnetic Properties of [Cu(2)Zn(Hdmg)(2)(dmg)(2)(H(2)O)].0.5H(2)dmg.H(2)O (H(2)dmg = Dimethylglyoxime).

    PubMed

    Ruiz, Rafael; Julve, Miguel; Faus, Juan; Lloret, Francesc; Muñoz, M. Carmen; Journaux, Yves; Bois, Claudette

    1997-07-30

    A new heterotrinuclear complex of formula [Cu(2)Zn(Hdmg)(2)(dmg)(2)(H(2)O)].0.5H(2)dmg.H(2)O (C(18)H(34)Cu(2)N(9)O(11)Zn, 1) (H(2)dmg = dimethylglyoxime) has been synthesized and its crystal structure determined by single-crystal X-ray diffraction. It crystallizes in the triclinic system, space group P&onemacr;, with a = 11.414(1) Å, b = 11.992(3) Å, c =12.567(10) Å, alpha = 91.27(6) degrees, beta = 111.46(2) degrees, gamma = 112.24(2) degrees, and Z = 2. The structure consists of a chain of neutral [Cu(2)Zn(Hdmg)(2)(dmg)(2)(H(2)O)] trinuclear units and noncoordinated H(2)dmg and water molecules. The configuration around the zinc atom is distorted trigonal bipyramidal with four oximate oxygens from two [Cu(Hdmg)(dmg)](-) fragments (each one acting as a bidentate ligand through its deprotonated oximate oxygens in cis positions) occupying one axial and the three equatorial positions and an additional oximate oxygen from a symmetry-related [Cu(Hdmg)(dmg)](-) fragment filling the remaining axial position. The environment around Cu(1) and Cu(2) is distorted square pyramidal with four oximate nitrogen atoms building the equatorial plane. An oxygen atom [O(9)] from a water molecule and an oximate oxygen from a symmetry-related [Cu(Hdmg)(dmg)](-) fragment occupy the apical position of the square pyramids around Cu(1) and Cu(2), respectively. The trinuclear units are repeated through inversion centers standing at the middle of the Zn(1).Zn(1)(i) and Cu(2).Cu(2)(ii) vectors leading to a chain which runs parallel to the diagonal of the ac-plane. The Cu(1).Cu(2), Zn(1).Zn(1)(i), and Cu(2).Cu(2)(ii) separations are 5.506(2), 3.390(2), and 3.930(2) Å, respectively. 1 exhibits a characteristic ferromagnetic behavior with a continuous increase of the chi(M)T product as the temperature is lowered from 300 to 2.0 K. The field dependence of the magnetization at 2.0 K is consistent with a low-lying quintet state. The only efficient exchange pathways responsible for the overall

  15. 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.

  16. Voltammetric determination of the reversible potentials for [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10- over the pH range of 2-12: electrolyte dependence and implications for water oxidation catalysis.

    PubMed

    Liu, Yuping; Guo, Si-Xuan; Bond, Alan M; Zhang, Jie; Geletii, Yurii V; Hill, Craig L

    2013-10-21

    Voltammetric studies of the Ru-containing polyoxometalate water oxidation molecular catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-) where 1 represents the {Ru4O4(OH)2(H2O)4} core and 1(0) stands for its initial form with all ruthenium centers in the oxidation state IV) have been carried out in aqueous media over a wide range of pH (2-12 using Britton-Robinson buffer) and ionic strength. Well-defined voltammograms in buffered media are only obtained when Frumkin double layer effects are suppressed by the presence of a sufficient concentration of additional supporting electrolyte (LiNO3, NaNO3, KNO3, Ca(NO3)2, Mg(NO3)2, MgSO4, or Na2SO4). A combination of data derived from dc cyclic, rotating disk electrode, and Fourier transformed large amplitude ac voltammetry allow the assignment of two processes related to reduction of the framework and the complete series of Ru(III/IV) and Ru(IV/V) redox processes and also provide their reversible potentials. Analysis of these data reveals that K(+) has a significantly stronger interaction with 1(1) (the number inside bracket stands for the number of electrons removed from 1(0)) than found for the other cations investigated, and hence its presence significantly alters the pH dependence of the 1(0)/1(1) reversible potential. Comparison of experimental data with theory developed in terms of equilibrium constants for process 1(0)/1(1) reveals that both H(+) and K(+) interact competitively with both 1(0) and 1(1). Importantly, reversible potential data reveal that (i) proton transfer does not necessarily need to be coupled to all electron transfer steps to achieve catalytic oxidation of water, (ii) the four-electron oxidized form, 1(4), is capable of oxidizing water under all conditions studied, and (iii) under some conditions, the three-electron oxidized form, 1(3), also exhibits considerable catalytic activity.

  17. Prediction of enthalpy of formation based on refined crystal structures of multisite compounds: Part 2. Application to minerals belonging to the system Li 2O-Na 2O-K 2O-BeO-MgO-CaO-MnO-FeO-Fe 2O 3-Al 2O 3-SiO 2-H 2O. Results and discussion

    NASA Astrophysics Data System (ADS)

    Vieillard, Philippe

    1994-10-01

    The method of prediction of enthalpy of formation of a multi-site compound has been developed in Part 1. This method of prediction is based on the use of the following parameters coming from the crystal structure refinements: first by spatial group, bond lengths, shortest bond lengths, molecular volume, and second from the optical properties. Part 2 shows the application of this method with 180 minerals and synthetic compounds belonging to the system Li 2O-Na 2O-K 2O-BeO-MgO-CaO-MnO-FeO-Fe 2O 3-Al 2O 3-SiO 2-H 2O which are gathered in a series of tables according to the spatial group and also to the nature of the family: hydroxides, metasilicates, orthosilicates, pyroxenes, olivines, feldspars, melilites, garnets, aluminates, ferrites, oxoferrates, spinels, phyllosilicates, hydrosilicates, amphiboles, and zeolites. The mean of absolute residual error is 0.59%. Among the twenty-three compounds exhibiting a residual error greater than ±1%, are some hydrogen-bearing minerals which may have a predicted enthalpy of formation from oxides closer to the experimental data by taking into consideration the orientation of water molecules and the hydrogen around the oxygens. This study initially demonstrated for lawsonite, may be applied to other hydrogen-bearing minerals such as natrolite, scolecite, mesolite, yugawaralite, clinochlore, cookeite, carpholite, and chloritoid. From the available recent crystal refinements of some minerals, the enthalpies of formation have been evaluated for the following minerals:

  18. 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.

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

    PubMed

    Paschalidis, Damianos G; Harrison, William T A

    2016-02-01

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

  20. 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.

  1. 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

  2. Synthesis and structure of decaaqua-hexasodium-calcium bis-nitrilotris(methylenephosphonate) bis(hexaaquasodium) tetrahydrate [CaNa6{NH(CH2PO3)3}2(H2O)10][Na(H2O)6]2 · 4H2O

    NASA Astrophysics Data System (ADS)

    Somov, N. V.; Chausov, F. F.; Zakirova, R. M.

    2017-05-01

    The product of the reaction of tetrasodium nitrilotris(methylenephosphonate) Na4H(NH(CH2PO3)3) with Ca(OH)2 having the formula [CaNa6{NH(CH2PO3)3}2(H2O)10][Na(H2O)6]2 · 4H2O (sp. gr. P21/ c, Z = 2, a = 12.0579(4) Å, b = 10.4569(3) Å, c = 19.9346(4) Å, β = 95.355(2)°) was synthesized and characterized. The complex anion consists of a ring composed of six hydrate-bridged Na atoms. The cavity of the anion incorporates a Ca atom coordinated by two phosphonate ligands in a distorted octahedral geometry. Each of the two complex cations contains a sodium ion octahedrally coordinated by six water molecules. The crystal packing consists of infinite ribbons of the complex anions, which are linked by hydrate bridges to form layers alternating with layers of the complex cations and interlayers composed of disordered water molecules of solvation.

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

    PubMed

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

    2014-11-26

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

  4. 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.

  5. 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).

  6. 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.

  7. [N(CH3)4]2[Mn(H2O)]3[Mo(CN)7](2).2H2O: a new high Tc cyano-bridged ferrimagnet based on the [MoIII(CN)7]4- building block and induced by counterion exchange.

    PubMed

    Larionova, Joulia; Clérac, Rodolphe; Donnadieu, Bruno; Guérin, Christian

    2002-06-17

    The title compound was synthesized by slow diffusion of aqueous solutions containing K4[Mo(CN)7].2H2O, [Mn(H2O)6](NO3)2, and [N(CH3)4]Cl. The compound crystallized in monoclinic space group C2/c, a = 25.8546(14), b = 12.3906(7), c = 13.5382(7) A, beta = 116.4170 (10) degrees, Z = 4, R = 0.0353, wR2 = 0.0456. The MoIII site is surrounded by six -C-N-Mn linkages and one terminal cyano group in a distorted capped-prism fashion. There are two pentahedral MnII sites in the structure, both with four -N-C-Mo linkages and one water molecule. The anisotropic three-dimensional structure consists of connected corrugated gridlike sheet layers parallel to the bc plane. Tetramethylammonium counterions ([N(CH3)4]+) located between these layers seem to induce their distortion. The three-dimensional organization may also be viewed as interconnected octagonal channels propagated along the c axis. The void space of these channels is occupied by coordinated and crystalized water molecules. Temperature and field dependence of the magnetization in both the dc and ac modes have been measured on polycrystalline sample. These investigations have revealed that the compound ordered ferrimagnetically at Tc = 86 K, with a small hysteresis effect. These findings have been compared to those reported previously for three- and two-dimensional materials of the same family.

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

    PubMed

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

    2002-11-18

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

  9. 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.

  10. 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

  11. 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.

  12. Syntheses, Crystal Structures, and Nonlinear Optical Activity of Cs2Ba[AnO2(C2H5COO)3]4 (An = U, Np, Pu) and Unprecedented Octanuclear Complex Units in KR2(H2O)8[UO2(C2H5COO)3]5 (R = Sr, Ba).

    PubMed

    Serezhkin, Viktor N; Grigoriev, Mikhail S; Abdulmyanov, Aleksey R; Fedoseev, Aleksandr M; Savchenkov, Anton V; Stefanovich, Sergey Yu; Serezhkina, Larisa B

    2017-06-19

    X-ray diffraction was applied to the elucidation of crystal structures of single crystals of Cs2Ba[AnO2(C2H5COO)3]4, where An = U(I), Np(II), Pu(III), and KR2(H2O)8[UO2(C2H5COO)3]5, where R = Sr(IV), Ba (polymorphs V-a and V-b). FTIR spectra were analyzed for the uranium-containing crystals I, IV, and V-b. Isostructural cubic crystals I-III are constructed of typical mononuclear anionic complex units [AnO2(C2H5COO)3](-) and charge-balancing Cs and Ba cations. Features of actinide contraction in the six U-Np-Pu isostructural series known to date are analyzed. In crystal structures of IV and V two typical complexes [UO2(C2H5COO)3](-) bind with a hydrated Sr or Ba cation to form the rare trinuclear neutral complex unit {R(H2O)4[UO2(C2H5COO)3]2}, where R = Sr, Ba. Two such trinuclear units and one typical mononuclear unit further bind with a K cation to form the unprecedented octanuclear neutral complex unit K[UO2(C2H5COO)3]{R(H2O)4[UO2(C2H5COO)3]2}2. As the derived polynuclear complexes of uranyl ion with carboxylate ligands in the crystal structures of IV and V are not the first but are rare examples, the equilibrium between mono and polynuclear complex units in aqueous solutions is discussed. The two polymorphic modifications V-a and V-b were studied at 100 K and at room temperature, respectively. Peculiarities of noncovalent interactions in crystal structures of the two polymorphs are revealed using Voronoi-Dirichlet tessellation. The nonlinear optical activity of noncentrosymmetric crystals I was estimated by its ability for second harmonic generation.

  13. Synthesis, spectral characterization, and structural studies of 2-aminobenzoate complexes of divalent alkaline earth metal ions: X-ray crystal structures of [Ca(2-aba)2(OH2)3]infinity, [[Sr(2-aba)2(OH2)2].H2O]infinity, and [Ba(2-aba)2(OH2)]infinity (2-abaH = 2-NH2C6H4COOH).

    PubMed

    Murugavel, R; Karambelkar, V V; Anantharaman, G; Walawalkar, M G

    2000-04-03

    Reactions of alkaline earth metal chlorides with 2-aminobenzoic acid (2-abaH) have been investigated. The treatment of MCl2.nH2O (M = Mg, Ca, Sr or Ba) with 2-abaH in a 1:2 ratio in a MeOH/H2O/NH3 mixture leads to the formation of anthranilate complexes [Mg(2-aba)2] (1), [Ca(2-aba)2(OH2)3]infinity (2), [[Sr(2-aba)2(OH2)2].H2O)]infinity (3), and [Ba(2-aba)2(OH2)]infinity (4) respectively. Alternatively, these products can also be obtained starting from the corresponding metal acetates. Anthranilate complexes 1-4 have been characterized with the aid of elemental analysis, pH measurements, thermal analysis, and infrared, ultraviolet, and NMR (1H and 13C) spectroscopic studies. All the products are found to be thermally very stable and do not melt on heating to 250 degrees C. Thermal studies of complexes 2-4, however, indicate the loss of coordinated and lattice water molecules below 200 degrees C. In the case of the magnesium complex, the analytical and thermogravimetric studies indicate the absence of any coordinated or uncoordinated water molecules. Further, the solid-state structures of metal anthranilates 2-4 have been established by single-crystal X-ray diffraction studies. While the calcium ions in 2 are heptacoordinated, the strontium and barium ions in 3 and 4 reveal a coordination number of 9 apart from an additional weak metal-metal interaction along the polymeric chains. The carboxylate groups show different chelating and bridging modes of coordination behavior in the three complexes. Interestingly, apart from the carboxylate functionality, the amino group also binds to the metal centers in the case of strontium and barium complexes 3 and 4. However, the coordination sphere of 2 contains only O donors. All three compounds form polymeric networks in the solid state with the aid of different coordinating capabilities of the carboxylate anions and O-H...O and N-H...O hydrogen bonding interactions.

  14. 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.

  15. 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.

  16. A semi-empirical thermodynamic formalism for high-pressure aqueous silicate solutions in the model system K2O-Na2O-CaO-MgO-Al2O3-SiO2-H2O-CO2, a first approach

    NASA Astrophysics Data System (ADS)

    Schertl, H.; Burchard, M.; Hertwig, A.; Maresch, W. V.

    2012-12-01

    The results of experimental solubility determinations in aqueous solutions at high pressures up to 5 GPa are often difficult to gauge with respect to precision and accuracy, because of the potential uncertainties inherent in the available experimental approaches. Existing models of aqueous silicate solutions at low pressures are either unsuitable for extrapolation beyond 0.5 to 1.0 GPa or involve polynomial fits in which the fit parameters lack direct physical meaning. An approach described by Gerya et al. [1,2], based on statistical thermodynamics, allows aqueous silicate solutions to be described as mixtures of fictive oxide "components" together with water molecules in both clustered and "gas-like", i.e. unassociated, states. Burchard et al. [3] presented a first data set for fluids in the system CaO-SiO2-H2O, using the statistical thermodynamic formulation of Gerya et al [1,2] and extending it to include charged fluid species such as Ca2+, Ca(OH)+, Ca(OH)2, OH- and H+. We have now further developed the data set of Burchard et al. [3] by including carbonic fluid species and extending the model system to include MgO and Al2O3. In addition, initial progress has been made in including potassium and sodium model species. Solid phase data were obtained by mathematical conversion of existing thermodynamic mineral data into the semi-empirical form. With this semi-empirical data set calculations for simple, "wet" silicate rocks are now possible. We present applications to suites of jadeitites and jadeite-lawsonite-quartz rocks from the Rio San Juan serpentinite mélanges of the northern Dominican Republic. These rocks have crystallized from high-pressure aqueous fluids in a long-lived intra-oceanic subduction-zone environment at various times and at different P-T conditions (Schertl et al. [4]). The fluid-rock interactions leading to these spectacular rocks are still poorly understood. [1] Gerya et al. (2004) Phys. Chem. Minerals 31, 429-455; [2] Gerya et al. (2005) Eur

  17. Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. II. Systems M1, M2//SO{4/2-}-H2O (M1, M2 = Fe2+, Fe3+, Cu2+, Zn2+, Pb2+, Ni2+, Co2+, H+) at 25°C

    NASA Astrophysics Data System (ADS)

    Charykova, M. V.; Krivovichev, V. G.; Depmeier, W.

    2010-12-01

    High toxicity of arsenic and selenium makes it important to analyze conditions, under which sulfates, arsenates, and selenites replace sulfides, arsenides, and selenides in the oxidation zones of sulfide ore deposits and in weathered technogenic waste. Published experimental data have been summarized for solubility in ternary systems containing Fe, Cu, Zn, Pb, Ni, and Co sulfates. Due to high solubility of solid phases, the thermodynamic description of solutions was carried out using the Pitzer equations; the necessary parameters were found in the literature or calculated in this article. The applied model was preliminarily verified by experimentally obtained diagrams of solubility. A database was compiled for quantitative thermodynamic modeling of mineral equilibria in most ternary and four-component subsystems of the Fe2+, Cu2+, Zn2+, Ni2+, Co2+//SO{4/2-}-H2O system. The lack of experimental data for the systems containing Fe(III) sulfate does not allow calculating necessary parameters of its interaction with other sulfates and conducting calculations in multicomponent systems without simplifications and additional assumptions. Solubility diagrams are considered for the following systems: FeSO4-H2SO4-H2O, NiSO4-H2SO4-H2O, CuSO4-H2SO4-H2O, ZnSO4-H2SO4-H2O, CoSO4-H2SO4-H2O, FeSO4-Fe2(SO4)3-H2O, CoSO4-NiSO4-H2O, ZnSO4NiSO4-H2O, FeSO4-CoSO4-H2O, FeSO4-NiSO4-H2O, FeSO4-CuSO4-H2O, CoSO4-CuSO4-H2O, NiSO4-CuSO4-H2O, and ZnSO4-CoSO4-H2O. For some of these systems, equilibrium phase diagrams are calculated in this article.

  18. 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.

  19. 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

  20. 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.

  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. 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.

  3. Pressure Induced Local Structure Distortions in Cu(pyz)F2(H2O)2

    SciTech Connect

    Musfeldt, J.L.; Carr, G.; Liu, Z.; Li, S.; Kang, C.L., Jena, P.; Manson, J.L.; Schlueter, J.A. Whangbo, M.H.

    2011-06-06

    We employed infrared spectroscopy along with complementary lattice dynamics and spin density calculations to investigate pressure-driven local structure distortions in the copper coordination polymer Cu(pyz)F{sub 2}(H{sub 2}O){sub 2}. Here, pyz is pyrazine. Our study reveals rich and fully reversible local lattice distortions that buckle the pyrazine ring, disrupt the bc-plane O-H {hor_ellipsis} F hydrogen-bonding network, and reinforce magnetic property switching. The resiliency of the soft organic ring is a major factor in the stability of this material. Interestingly, the collective character of the lattice vibrations masks direct information on the Cu-N and Cu-O linkages through the series of pressure-induced Jahn-Teller axis switching transitions, although Cu-F bond softening is clearly identified above 3 GPa. These findings illustrate the importance of combined bulk and local probe techniques for microscopic structure determination in complex materials.

  4. Pressure-Induced Local Structure Distortions in Cu(pyz)F(2)(H(2)O)(2)

    SciTech Connect

    J Musfeldt; Z Liu; S Li; J Kang; C Lee; P Jena; J Manson; J Schlueter; G Carr; M Whangbo

    2011-12-31

    We employed infrared spectroscopy along with complementary lattice dynamics and spin density calculations to investigate pressure-driven local structure distortions in the copper coordination polymer Cu(pyz)F{sub 2}(H{sub 2}O){sub 2}. Here, pyz is pyrazine. Our study reveals rich and fully reversible local lattice distortions that buckle the pyrazine ring, disrupt the bc-plane O-H {hor_ellipsis} F hydrogen-bonding network, and reinforce magnetic property switching. The resiliency of the soft organic ring is a major factor in the stability of this material. Interestingly, the collective character of the lattice vibrations masks direct information on the Cu-N and Cu-O linkages through the series of pressure-induced Jahn-Teller axis switching transitions, although Cu-F bond softening is clearly identified above 3 GPa. These findings illustrate the importance of combined bulk and local probe techniques for microscopic structure determination in complex materials.

  5. 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.

  6. 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.

  7. 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.

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

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.

    1986-01-01

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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Standardized Automated CO2/H2O Flux Systems for Individual Research Groups and Flux Networks

    NASA Astrophysics Data System (ADS)

    Burba, George; Begashaw, Israel; Fratini, Gerardo; Griessbaum, Frank; Kathilankal, James; Xu, Liukang; Franz, Daniela; Joseph, Everette; Larmanou, Eric; Miller, Scott; Papale, Dario; Sabbatini, Simone; Sachs, Torsten; Sakai, Ricardo; McDermitt, Dayle

    2017-04-01

    In recent years, spatial and temporal flux data coverage improved significantly, and on multiple scales, from a single station to continental networks, due to standardization, automation, and management of data collection, and better handling of the extensive amounts of generated data. With more stations and networks, larger data flows from each station, and smaller operating budgets, modern tools are required to effectively and efficiently handle the entire process. Such tools are needed to maximize time dedicated to authoring publications and answering research questions, and to minimize time and expenses spent on data acquisition, processing, and quality control. Thus, these tools should produce standardized verifiable datasets and provide a way to cross-share the standardized data with external collaborators to leverage available funding, promote data analyses and publications. LI-COR gas analyzers are widely used in past and present flux networks such as AmeriFlux, ICOS, AsiaFlux, OzFlux, NEON, CarboEurope, and FluxNet-Canada, etc. These analyzers have gone through several major improvements over the past 30 years. However, in 2016, a three-prong development was completed to create an automated flux system which can accept multiple sonic anemometer and datalogger models, compute final and complete fluxes on-site, merge final fluxes with supporting weather soil and radiation data, monitor station outputs and send automated alerts to researchers, and allow secure sharing and cross-sharing of the station and data access. Two types of these research systems were developed: open-path (LI-7500RS) and enclosed-path (LI-7200RS). Key developments included: • Improvement of gas analyzer performance • Standardization and automation of final flux calculations onsite, and in real-time • Seamless integration with latest site management and data sharing tools In terms of the gas analyzer performance, the RS analyzers are based on established LI-7500/A and LI-7200 models, and the improvements focused on increased stability in the presence of contamination, refining temperature control and compensation, and providing more accurate fast gas concentration measurements. In terms of the flux calculations, improvements focused on automating the on-site flux calculations using EddyPro® software run by a weatherized fully digital microcomputer, SmartFlux2. In terms of site management and data sharing, the development focused on web-based software, FluxSuite, which allows real-time station monitoring and data access by multiple users. The presentation will describe details for the key developments and will include results from field tests of the RS gas analyzer models in comparison with older models and control reference instruments.

  14. 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

  15. 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.

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

    DOE Data Explorer

    Kristin Persson

    2014-11-02

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

  17. 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

  18. 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

  19. 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.

  20. 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.

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

    PubMed

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

    2014-05-06

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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. [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

  7. 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.

  8. 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.

  9. Materials Data on CaAl2Si2(H2O5)2 (SG:33) by Materials Project

    SciTech Connect

    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

  10. Materials Data on CaAl2Si2(H2O5)2 (SG:63) 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

  11. Materials Data on CaAl2Si2(H2O5)2 (SG:62) by Materials Project

    DOE Data Explorer

    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

  12. Materials Data on CaAl2Si2(H2O5)2 (SG:63) 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

  13. A DFT study of the hematite surface state in the presence of H2, H2O and O2

    NASA Astrophysics Data System (ADS)

    Souvi, Sidi M. O.; Badawi, Michael; Paul, Jean-François; Cristol, Sylvain; Cantrel, Laurent

    2013-04-01

    Hematite materials are of crucial interest since they are involved in many physico-chemical applications. However, the α-Fe2O3 surface state depends on temperature and surrounding gas composition and pressure. The hydrogen, oxygen and water coverage, the structure and thermodynamic stability of (0001) α-Fe2O3 surfaces have been investigated in the DFT + U framework as a function of temperature and partial pressures taking into account the spin effect. In the 300-900 K temperature range, it is mandatory to take into account water adsorption: the outermost iron atoms will be almost fully hydroxylated decreasing the acidic (Lewis) character of the surface. The chemistry of the surface will be dominated by hydrogen bonds. Above 900 K, only the Fe-termination and simply hydrogenated terminations are stable and must be considered.

  14. 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.

  15. 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.

  16. Increase of the uranium release at an UO 2/H 2O interface under He 2+ ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Corbel, Catherine; Sattonnay, Gaël; Lucchini, Jean-François; Ardois, Christophe; Barthe, Marie-France; Huet, François; Dehaudt, Pierre; Hickel, Bernard; Jegou, Christophe

    2001-07-01

    The release of uranium in aerated deionized water at a uranium oxide/water interface under He 2+ irradiation is investigated as a function of the fluence by using an external ion beam. A high-energy He 2+ beam delivered by a cyclotron (CERI-CNRS) goes through the thin oxide and emerges in the water with 20 MeV energy. First results are reported here showing that the release of uranium increases by three orders of magnitude in aerated deionized water under high flux (⩾ 3.3×10 10 α cm -2 s-1).

  17. Ternary Isothermal Diffusion Coefficients of NaCl-MgCl2-H2O at 25 C. 7. Seawater Composition

    SciTech Connect

    Miller, D G; Lee, C M; Rard, J A

    2007-02-12

    The four diffusion coefficients D{sub ij} of the ternary system NaCl-MgCl{sub 2}-H{sub 2}O at the simplified seawater composition 0.48877 mol {center_dot} dm{sup -3} NaCl and 0.05110 mol {center_dot} dm{sup -3} MgCl{sub 2} have been remeasured at 25 C. The diffusion coefficients were obtained using both Gouy and Rayleigh interferometry with the highly precise Gosting diffusiometer. The results, which should be identical in principle, are essentially the same within or very close to their combined 'realistic' errors. This system has a cross-term D{sub 12} that is larger than the D{sub 22} main-term, where subscript 1 denotes NaCl and 2 denotes MgCl{sub 2}. The results are compared with earlier, less-precise measurements. Recommended values for this system are (D{sub 11}){sub V} = 1.432 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, (D{sub 12}){sub V} = 0.750 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, (D{sub 21}){sub V} = 0.0185 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, and (D{sub 22}){sub V} = 0.728 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}.

  18. CFD convective flow simulation of the varying properties of CO2-H2O mixtures in geothermal systems.

    PubMed

    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.

  19. 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.

  20. Formation of primary kimberlite melts - Constraints from experiments at 6-12 GPa and variable CO2/H2O

    NASA Astrophysics Data System (ADS)

    Girnis, A. V.; Bulatov, V. K.; Brey, G. P.

    2011-12-01

    Liquidus phase relations were experimentally studied in model kimberlite melts at 6-12 GPa. Four starting materials were used with different CO2 and H2O contents but almost identical proportions of other components (~ 35 wt.% SiO2, 3 wt.% Al2O3, 10 wt.% FeO, 33 wt.% MgO, 15 wt.% CaO, 0.3 wt.% Na2O, and 1 wt.% K2O on a 100% volatile-free basis). The liquidus phase of the CO2 richest mixture (33 wt.% CO2 and no H2O) is coesite at P > 6-8 GPa and low-Ca pyroxene at lower pressures. In an H2O-free mixture with lower CO2 content (18 wt.%) low-Ca pyroxene is the main liquidus phase and coesite was never observed in the experimental products. The addition of water (mixtures with 10 wt.% H2O + 9 wt.% CO2 and 12 wt.% H2O + 5 wt.% CO2) depresses the liquidus temperature and expands the crystallization field of olivine. At high pressures (> 8 GPa), garnet crystallization dominates near-liquidus phase relations. Based on the experimental data, possible conditions of the simultaneous saturation of kimberlite melt with olivine + low-Ca pyroxene ± garnet were estimated. High-Ca pyroxene was never found in the near-liquidus assemblages despite the high-CaO compositions of the starting mixtures. It was shown that the supposed primary kimberlite melt can be in equilibrium with the garnet harzburgite assemblage at 6-8 GPa and variable volatile contents, from ~ 15 wt.% CO2 under anhydrous conditions to 20 wt.% H2O and low CO2. These conditions correspond to possible parameters of kimberlite magma generation by partial melting of carbonated garnet harzburgite in the lithospheric mantle. The primary CO2 content could be higher if the kimberlite magma was poorer in SiO2 (more ‘carbonatitic'). The maximum CO2 content is limited by the appearance of magnesite on the liquidus at 20-22 wt.%, which is much lower than CO2 solubility in kimberlite melt at 7-8 GPa (> 30 wt.%). The content of H2O in primary kimberlite magmas depends on the bulk H2O content in the source, because no hydrous phases are stable near the kimberlite liquidus.

  1. 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.

  2. 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

  3. High-pressure behavior of 10 Å phase (Mg3Si4O10(OH)2.H2O)

    NASA Astrophysics Data System (ADS)

    Mookherjee, M.; Kalvan, E.; Hermann, A.

    2016-12-01

    Layered hydrous phases such as serpentine (Mg3Si2O5(OH)4), talc (Mg3Si4O10(OH)2), chlorite (Mg5Al(Si3Al)O10(OH)8), and 10 Å phase (Mg3Si4O10(OH)2.xH2O, where x=1,2) play important roles in transporting water into the Earth's interior. Using first principles simulations, we investigate the high-pressure behavior of 10 Å phase. In particular, we investigate the crystal structure of 10 Å phase and how it evolves upon compression. The predicted lattice parameters from the first principles simulations are in good agreement with the previous x-ray diffraction studies. The energy vs. volume results can be expressed in terms of a Birch-Murnaghan finite strain fit, with parameters, V0, K0 and K0' being 525.7 Å3, 32.1 GPa, and 17.4 respectively. The predicted V0 is greater than that of the experimentally determined value by 5.4 %. This discrepancy is often typical for the density functional theory calculations based on Genaralized Gradient Approximations (GGA). We are exploring the elasticity of 10 Å phase and how it varies as a function of pressure. The layered hydrous silicates such as serpentine, chlorite, and talc are often assicated with significant elastic anisotropy and are often responsible for the large delay times observed in certain subduction zones. We will accurately constrain the sound wave velocity and elastic anisotropy of 10 Å phase to gain insight into the degree of shallow mantle hydration and explain geophysical observations pertaining to subduction zones. Acknowledgements: The research is supported by NSF EAR 1639552, 1634422.

  4. 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.

  5. 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.

  6. Was the lethal eruption of Lake Nyos related to a double CO 2/H 2O density inversion?

    NASA Astrophysics Data System (ADS)

    Touret, Jacques; Grégoire, Michel; Teitchou, Merlin

    2010-01-01

    The 1986 lethal eruption of Lake Nyos (Cameroon) was caused by a sudden inversion between deep, CO 2-loaded bottom lake waters and denser, gas-free surface waters. A deep CO 2 source has been found in fluid inclusions which occur predominantly in clinopyroxenes from lherzolitic mantle xenoliths, brought to the surface by the last erupted alkali basalts. P-T conditions of CO 2 trapping correspond to a gas density equal (or higher) than that of liquid water. It is suggested that this dense CO 2, found in many ultrabasic mantle xenoliths worldwide, has accumulated at km depth, below a column of descending lake water. It may remain in a stable state for a long period, as long as the temperature is above the density inversion temperature for pure H 2O/CO 2 systems. At an estimated depth of about 3 km, cooling by descending waters (to about 30 °C) induces a density inversion for the upper part of the CO 2 reservoir. This causes a constant, regular upstream of low-density CO 2 which, in its turn, feeds the shallower lake density inversion.

  7. CO2-H2O Phase Equilibria: Residual Ice Layers and Basal Melting of the Martian Polar Ice Caps

    NASA Astrophysics Data System (ADS)

    Longhi, J.

    2004-03-01

    Shifts in saturation surfaces with pressure favor residual layers of solid CO_2 at the martian south pole. Basal melting of solid-CO_2 layers within polar ice caps during periods of low obliquity may lead to storage of liquid CO_2 in the Martian crust.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Ionic and superionic phases in ammonia dihydrate N H3.2 H2O under high pressure

    NASA Astrophysics Data System (ADS)

    Jiang, Xue; Wu, Xue; Zheng, Zhaoyang; Huang, Yingying; Zhao, Jijun

    2017-04-01

    Water and ammonia have long been seen as the main species of extraterrestrial space, especially on solar giants, moons, comets, and numerous extrasolar planets. The phases formed by their admixtures under temperature and pressure conditions of the giant planets are important for understanding many observable properties (gravitational moments, atmospheric composition, and magnetic field). Here we employ a Monte Carlo packing algorithm combined with first-principles calculations to search the low-energy crystal structures of ammonia dihydrate (ADH). At high pressure above 11.81 GPa, we predict an unusual ionic phase (tetragonal, I 41c d ) consisting of three alternating layers of H2O ,NH4+ , and O H- . The occurrence of ionic phase is attributed to the NH4+ and O H- electrostatic interaction induced volume reduction, which lowers the energy barrier of molecular to ionic phase transition. Analysis of proton transfer under pressure further supports the transformation mechanism between molecular and ionic phase. According to the mobility of hydrogen atoms from ab initio molecular dynamics, this ionic crystal will transform into a superionic phase under high temperature and high pressure. The existence of ionic or superionic ADH may have important implications for understanding the interiors of Neptune, Uranus, and many extrasolar planets.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

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

    DTIC Science & Technology

    1995-07-01

    second only to organochlorine functional groups. NACs are common environmental contaminants because of their use as munitions, insecticides, herbicides...metal corrosion. Metal corrosion is an electrochemical process, in which oxidation of Fe° to Fe2+ is the anodic half-reaction. The associated...synthetic chemistry, or model reactions for electrochemical investigations, and numerous reviews on these topics are available.3*5-^ in almost all

  10. 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.

  11. Global minima and energetics of Li +(H 2O) n and Ca 2+(H 2O) n clusters for n ⩽ 20

    NASA Astrophysics Data System (ADS)

    González, Briesta S.; Hernández-Rojas, Javier; Wales, David J.

    2005-08-01

    We present candidate structures for the global potential energy minima of X(H 2O) n (X = Li +, Ca 2+) clusters with n ⩽ 20. The TIP4P rigid body water-water potential is employed, together with cation-water interactions that are represented as a sum of Coulomb and Lennard-Jones terms. We find that in the Li + global minima the cation tends to be located on the cluster surface with a preferred coordination number of four water molecules in tetrahedral positions. In contrast, for Ca 2+ clusters the cation occupies an interior site surrounded by eight water molecules in a square anti-prismatic arrangement.

  12. Experimental Constraints on Silicic Slab Melt and Depleted Mantle Reaction in the Presence of CO2-H2O: Implications for the Origin of Mid Lithospheric Discontinuity

    NASA Astrophysics Data System (ADS)

    Saha, S.; Dasgupta, R.; Tsuno, K.

    2016-12-01

    Seismic shear wave velocity, VS drop (upto 24% and mostly 2-7%) observed globally beneath continents at depths of 60-160 km, known as the Mid Lithospheric Discontinuity (MLD) [e.g., 1], is an enigmatic feature of cratons whose origin is highly debated [e.g., 2, 3]. One of the mechanisms that can explain the MLD is the presence of volatile bearing phases such as partial melts and/or hydrous or carbonate minerals at depths. However, the compositional vector and geodynamic scenario required for their formation and the proportion and composition of infiltrating melt or fluid that may lead to their stability is poorly known at present. We performed high P-T experiments equilibrating a depleted peridotite (Mg# 92) with variable proportion of a H2O-CO2 bearing silicic melt, interaction that could occur during the formation of continents by imbrication of slabs. The first set of experiments were performed with 10 wt.% melt (0.9 wt.% H2O and 0.5 wt.% CO2 in the bulk) at 950-1175 °C at 3 GPa using a piston cylinder and 950-1150 °C at 4 GPa using a multi anvil apparatus. Olivine, opx, cpx, garnet/spinel and phlogopite (5-6%) are present in all runs. Amphibole (3.5-9.5%) is present at 3 GPa and ≤1050 °C. Magnesite ( 1%) is present at ≤1000 °C at 3 and ≤1050 °C at 4 GPa. Trace melt is observed along the grain boundaries above 1000 °C at 3 GPa and 1050 ° C at 4 GPa, respectively. Mineral modes obtained by mass balance calculations, ignoring the presence of melts, were used to calculate VS of the resulting assemblages [4]. The calculated drops in VS at 3 GPa (3.8-4.5%) and 4 GPa (1.6-3.2%) are well within the range of velocity drops for MLDs observed globally. Further experiments on different melt-rock ratios are underway and will constrain how modal proportion of hydrous and carbonate minerals varies as a function of melt:rock ratio and bulk volatile contents. [1] Abt et al., 2010, JGR; [2] Rader et al., 2015, G3; [3] Karato et al., 2015, NatGeo [4] Abers & Hacker, 2016, G3

  13. 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.

  14. Development and Field Testing of the Latest Open-path and Enclosed-Path CO2/H2O Flux Measurement and Research Systems

    NASA Astrophysics Data System (ADS)

    Begashaw, I. G.; Fratini, G.; Griessbaum, F.; Kathilankal, J. C.; Xu, L.; Franz, D.; Joseph, E.; Larmanou, E.; Miller, S. D.; Papale, D.; Sabbatini, S.; Sachs, T.; Sakai, R.; McDermitt, D. K.; Burba, G. G.

    2016-12-01

    LI-COR gas analyzers are widely used in past and present flux networks such as AmeriFlux, ICOS, AsiaFlux, OzFlux, CarboEurope, FluxNet-Canada and others. These analyzers have undergone several improvements over the past 20 years. In 2015 new open-path and enclosed-path flux research systems (RS models) were developed based on established LI-7500/A and LI-7200 gas analyzer models, with the goal of improving stability in the presence of contamination, refining temperature control and compensation, and providing more accurate gas concentration measurements. In addition, both systems perform automated on-site flux calculations using EddyPro® software run by a weatherized module, SmartFlux® 2. These improvements reduce errors in mean CO2 and H2O concentration, hourly fluxes and in long-term carbon and water budgets. Field tests of both systems were conducted over six periods, each 5-14 months long, at 6 sites with diverse environments and types of contamination, using 26 gas analyzers. The open-path LI-7500RS performed significantly better than the original LI-7500A model in terms of contamination-related drifts in mean concentrations of CO2 and H2O. Improvements in H2O contamination-related drifts were particularly significant, with RS models often drifting many tens of times less than the original. The enclosed LI-7200RS performed substantially better than the original LI-7200 in terms of the drifts in H2O, sometimes drifting few-to-tens of times less than the original. Improvements in CO2 contamination-related drifts were modest, similar or just a bit better than the original. Results from field tests suggest that both RS systems can: Reduce the frequency of cleaning and site visits for service and maintenance, especially for the open-path design Increase total data coverage over long periods of deployment, and the amount of high quality data, with low uncertainty The presentation will describe detailed results from field tests of these models in comparison with older models and control reference instruments.

  15. 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.

  16. 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.

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

    Treesearch

    John M. Frank; William J. Massman; Brent E. Ewers; Laurie S. Huckaby; Jose F. Negron

    2014-01-01

    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...

  18. 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.

  19. O2(b(1)Σg(+)) Quenching by O2, CO2, H2O, and N2 at Temperatures of 300-800 K.

    PubMed

    Zagidullin, M V; Khvatov, N A; Medvedkov, I A; Tolstov, G I; Mebel, A M; Heaven, M C; Azyazov, V N

    2017-09-26

    Rate constants for the removal of O2(b(1)Σg(+)) by collisions with O2, N2, CO2, and H2O have been determined over the temperature range from 297 to 800 K. O2(b(1)Σg(+)) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed by observing the temporal behavior of the b(1)Σg(+)-X(3)Σg(-) fluorescence. The removal rate constants for CO2, N2, and H2O were not strongly dependent on temperature and could be represented by the expressions kCO2 = (1.18 ± 0.05) × 10(-17) × T(1.5) × exp[Formula: see text], kN2 = (8 ± 0.3) × 10(-20) × T(1.5) × exp[Formula: see text], and kH2O = (1.27 ± 0.08) × 10(-16) × T(1.5) × exp[Formula: see text] cm(3) molecule(-1) s(-1). Rate constants for O2(b(1)Σg(+)) removal by O2(X), being orders of magnitude lower, demonstrated a sharp increase with temperature, represented by the fitted expression kO2 = (7.4 ± 0.8) × 10(-17) × T(0.5) × exp[Formula: see text] cm(3) molecule(-1) s(-1). All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.

  20. 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.

  1. 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

  2. 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.

  3. D/H fractionation in the H2-H2O system at supercritical water conditions: Compositional and hydrogen bonding effects

    NASA Astrophysics Data System (ADS)

    Foustoukos, Dionysis I.; Mysen, Bjorn O.

    2012-06-01

    A series of experiments has been conducted in the H2-D2-D2O-H2O-Ti-TiO2 system at temperatures ranging from 300 to 800 °C and pressures between ∼0.3 and 1.3 GPa in a hydrothermal diamond anvil cell, utilizing Raman spectroscopy as a quantitative tool to explore the relative distribution of hydrogen and deuterium isotopologues of the H2 and H2O in supercritical fluids. In detail, H2O-D2O solutions (1:1) were reacted with Ti metal (3-9 h) in the diamond cell, leading to formation of H2, D2, HD, and HDO species through Ti oxidation and H-D isotope exchange reactions. Experimental results obtained in situ and at ambient conditions on quenched samples indicate significant differences from the theoretical estimates of the equilibrium thermodynamic properties of the H-D exchange reactions. In fact, the estimated enthalpy for the H2(aq)-D2(aq) disproportionation reaction (ΔHrxn) is about -3.4 kcal/mol, which differs greatly from the +0.16 kcal/mol predicted for the exchange reaction in the gas phase by statistical mechanics models. The exothermic behavior of the exchange reaction implies enhanced stability of H2 and D2 relative to HD. Accordingly, the significant energy difference of the internal H2(aq)-D2(aq)-HD(aq) equilibrium translates to strong differences of the fractionation effects between the H2O-H2 and D2O-D2 isotope exchange relationships. The D/H fractionation factors between H2O-H2(aq) and D2O-D2(aq) differ by 365‰ in the 600-800 °C temperature range, and are indicative of the greater effect of D2O contribution to the δD isotopic composition of supercritical fluids. The negative ΔHrxn values for the H2(aq)-D2(aq)-HD(aq) equilibrium and the apparent decrease of the equilibrium constant with increasing temperature might be because of differences of the Henry’s law constant between the H- and D-bearing species dissolved in supercritical aqueous solutions. Such effects may be attributed to the stronger hydrogen bonding in the O-H⋯O relative to the O-D⋯O environment. This difference allows enhanced gas solubility in the denser and more polar H2O clusters, and thus, affects the D/H exchange between the H2-D2 volatiles and the coexisting H2O-D2O mixtures. The proposed role of temperature in promoting differences in the density and polarity of hydrogen-bonded OHO and ODO molecules may be explained with isotope-specific molar volume effects similar to those suggested to account for the hydrogen isotope fractionation between H2O and hydroxide mineral phases (e.g. brucite) across large pressure intervals.

  4. 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.

  5. EPR, ENDOR, and DFT study of free radicals in L-lysine·HCl·2H2O single crystals X-irradiated at 298 K.

    PubMed

    Zhou, Yiying; Nelson, William H

    2011-10-27

    With K-band EPR (Electron Paramagnetic Resonance), ENDOR (Electron-Nuclear DOuble Resonance), and EIE (ENDOR-induced EPR) techniques, three free radicals (RI-RIII) in L-lysine hydrochloride dihydrate single crystals X-irradiated at 298 K were detected at 298 K, and six radicals (R1, R1', R2-R5) were detected if the temperature was lowered to 66 K from 298 K. R1 and RI dominated the central portion of the EPR at 66 and 298 K, respectively, and were identified as main chain deamination radicals, (-)OOCĊH(CH(2))(4)(NH(3))(+). R1' was identified as a main chain deamination radical with the different configuration from R1 at 66 K, and it probably formed during cooling the temperature from 298 to 66 K. The configurations of R1, R1', and RI were analyzed with their coupling tensors. R2 and R3 each contain one α- and four β-proton couplings and have very similar EIEs at three crystallographic axes. The two-layer ONIOM calculations (at B3LYP/6-31G(d,p):PM3) support that R2 and R3 are from different radicals: dehydrogenation at C4, (-)OOCCH(NH(3))(+)CH(2)ĊH(CH(2))(2)(NH(3))(+), and dehydrogenation at C5, (-)OOCCH(NH(3))(+)(CH(2))(2)ĊHCH(2)(NH(3))(+), respectively. The comparisons of the coupling tensors indicated that R2 (66 K) is the same radical as RII (298 K), and R3 is the same as RIII. Thus, RII and RIII also are the radicals of C4 and C5 dehydrogenation. R4 and R5 are minority radicals and were observed only when temperature was lowered to 66 K. R4 and R5 were only tentatively assigned as the side chain deamination radical, (-)OOCCH (NH(3))(+)(CH(2))(3)ĊH(2), and the radical dehydrogenation at C3, (-)OOCCH(NH(3))(+)ĊH(CH(2))(3)(NH(3))(+), respectively, although the evidence was indirect. From simulation of the EPR (B//a, 66 K), the concentrations of R1, R1', and R2-R5 were estimated as: R1, 50%; R1', 11%; R2, 14%; R3, 16%; R4, 6%; R5, 3%.

  6. Kinetics of stabilised Criegee intermediates derived from alkene ozonolysis: reactions with SO2, H2O and decomposition under boundary layer conditions.

    PubMed

    Newland, Mike J; Rickard, Andrew R; Alam, Mohammed S; Vereecken, Luc; Muñoz, Amalia; Ródenas, Milagros; Bloss, William J

    2015-02-14

    The removal of SO2 in the presence of alkene-ozone systems has been studied for ethene, cis-but-2-ene, trans-but-2-ene and 2,3-dimethyl-but-2-ene, as a function of humidity, under atmospheric boundary layer conditions. The SO2 removal displays a clear dependence on relative humidity for all four alkene-ozone systems confirming a significant reaction for stabilised Criegee intermediates (SCI) with H2O. The observed SO2 removal kinetics are consistent with relative rate constants, k(SCI + H2O)/k(SCI + SO2), of 3.3 (±1.1) × 10(-5) for CH2OO, 26 (±10) × 10(-5) for CH3CHOO derived from cis-but-2-ene, 33 (±10) × 10(-5) for CH3CHOO derived from trans-but-2-ene, and 8.7 (±2.5) × 10(-5) for (CH3)2COO derived from 2,3-dimethyl-but-2-ene. The relative rate constants for k(SCI decomposition)/k(SCI + SO2) are -2.3 (±3.5) × 10(11) cm(-3) for CH2OO, 13 (±43) × 10(11) cm(-3) for CH3CHOO derived from cis-but-2-ene, -14 (±31) × 10(11) cm(-3) for CH3CHOO derived from trans-but-2-ene and 63 (±14) × 10(11) cm(-3) for (CH3)2COO. Uncertainties are ±2σ and represent combined systematic and precision components. These values are derived following the approximation that a single SCI is present for each system; a more comprehensive interpretation, explicitly considering the differing reactivity for syn- and anti-SCI conformers, is also presented. This yields values of 3.5 (±3.1) × 10(-4) for k(SCI + H2O)/k(SCI + SO2) of anti-CH3CHOO and 1.2 (±1.1) × 10(13) for k(SCI decomposition)/k(SCI + SO2) of syn-CH3CHOO. The reaction of the water dimer with CH2OO is also considered, with a derived value for k(CH2OO + (H2O)2)/k(CH2OO + SO2) of 1.4 (±1.8) × 10(-2). The observed SO2 removal rate constants, which technically represent upper limits, are consistent with decomposition being a significant, structure dependent, sink in the atmosphere for syn-SCI.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Isotopic (18O) signature of CO2-H2O vapor exchange in the vadose air of Nerja cave (Malaga, Spain)

    NASA Astrophysics Data System (ADS)

    Vadillo, Iñaki; Ojeda, Lucía; Benavente, José; Liñán, Cristina; del Rosal, Yolanda; Carrasco, Francisco

    2017-04-01

    In caves, carbon dioxide contents and its δ13C signature have been widely studied to provide information about the ventilation regime and the source of carbon dioxide. However, less has been researched about δ18O signature in vadose air. We analysed cave-air samples for the CO2 concentration and oxygen isotopic composition from a monthly sampling campaigns for two years within different halls in Nerja cave. In general terms, ventilation controls the variation of CO2 content seasonally, showing two distinct modes with the highest values in summer. The δ18O values range from -8.74 to +0.47 ‰ being maximum in January and minimum in September, coinciding with the lowest and highest humidity values within the cave respectively. We found that a gas exchange between δ18O-CO2 and δ18O-H2O vapor is carried out and pattern is repeated every season, showing the importance that water has in karst environment.

  14. Infrared and Raman spectroscopic characterization of the phosphate mineral fairfieldite--Ca2(Mn2+,Fe2+)2(PO4)2·2(H2O).

    PubMed

    Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; Belotti, Fernanda Maria; Lopez, Andres

    2013-04-01

    Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the phosphate mineral fairfieldite. The Raman phosphate (PO4)(3-) stretching region shows strong differences between the fairfieldite phosphate minerals which is attributed to the cation substitution for calcium in the structure. In the infrared spectra complexity exists with multiple (PO4)2- antisymmetric stretching vibrations observed, indicating a reduction of the tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong Raman bands around 600 cm(-1) are assigned to ν4 phosphate bending modes. Multiple bands in the 400-450 cm(-1) region assigned to ν2 phosphate bending modes provide further evidence of symmetry reduction of the phosphate anion. Three broadbands for fairfieldite are found at 3040, 3139 and 3271 cm(-1) and are assigned to OH stretching bands. By using a Libowitzky empirical equation hydrogen bond distances of 2.658 and 2.730Å are estimated. Vibrational spectroscopy enables aspects of the molecular structure of the fairfieldite to be ascertained. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. 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.

  16. 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