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Sample records for powder hydration time

  1. Glass powder blended cement hydration modelling

    NASA Astrophysics Data System (ADS)

    Saeed, Huda

    The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1

  2. Proton glass freezing in hydrated lysozyme powders.

    PubMed

    Levstik, A; Filipic, C; Kutnjak, Z; Careri, G; Consolini, G; Bruni, F

    1999-12-01

    At room temperature, the dielectric relaxation of hydrated powder of the protein lysozyme is known to be due to protons migrating between ionized side chains. A recent study of this relaxation at lower temperatures suggested a behavior typical of proton glasses. An analysis of the complex dielectric susceptibility by a temperature-frequency plot presented here has revealed that ergodicity is broken due to the divergence of the longest relaxation time at 266 K, indicating specifically that this hydrated protein is a proton glass. A change in the temperature behavior of the static dielectric constant and the average relaxation frequency at 273 K indicates a further transition occurring at this temperature, whose nature remains to be investigated.

  3. Hydrogen exchange of lysozyme powders. Hydration dependence of internal motions.

    PubMed

    Schinkel, J E; Downer, N W; Rupley, J A

    1985-01-15

    The rate of exchange of the labile hydrogens of lysozyme was measured by out-exchange of tritium from the protein in solution and from powder samples of varied hydration level, for pH 2, 3, 5, 7, and 10 at 25 degrees C. The dependence of exchange of powder samples on the level of hydration was the same for all pHs. Exchange increased strongly with increased hydration until reaching a rate of exchange that is constant above 0.15 g of H2O/g of protein (120 mol of H2O/mol of protein). This hydration level corresponds to coverage of less than half the protein surface with a monolayer of water. No additional hydrogen exchange was observed for protein powders with higher water content. Considered in conjunction with other lysozyme hydration data [Rupley, J. A., Gratton, E., & Careri, G. (1983) Trends Biochem. Sci. (Pers. Ed.) 8, 18-22], this observation indicates that internal protein dynamics are not strongly coupled to surface properties. The use of powder samples offers control of water activity through regulation of water vapor pressure. The dependence of the exchange rate on water activity was about fourth order. The order was pH independent and was constant from 114 to 8 mol of hydrogen remaining unexchanged/mol of lysozyme. These results indicate that the rate-determining step for protein hydrogen exchange is similar for all backbone amides and involves few water molecules. Powder samples were hydrated either by isopiestic equilibration, with a half-time for hydration of about 1 h, or by addition of solvent to rapidly reach final hydration. Samples hydrated slowly by isopiestic equilibration exhibited more exchange than was observed for samples of the same water content that had been hydrated rapidly by solvent addition. This difference can be explained by salt and pH effects on the nearly dry protein. Such effects would be expected to contribute more strongly during the isopiestic equilibration process. Solution hydrogen exchange measurements made for comparison

  4. Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

    PubMed Central

    Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

    2015-01-01

    In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system. PMID:28793560

  5. Influence of Ultrafine 2CaO·SiO₂ Powder on Hydration Properties of Reactive Powder Concrete.

    PubMed

    Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

    2015-09-17

    In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.

  6. Proton percolation on hydrated lysozyme powders.

    PubMed

    Careri, G; Giansanti, A; Rupley, J A

    1986-09-01

    The framework of percolation theory is used to analyze the hydration dependence of the capacitance measured for protein samples of pH 3-10, at frequencies from 10 kHz to 4 MHz. For all samples there is a critical value of the hydration at which the capacitance sharply increases with increase in hydration level. The threshold h(c) = 0.15 g of water per g of protein is independent of pH below pH 9 and shows no solvent deuterium isotope effect. The fractional coverage of the surface at h(c) is in close agreement with the prediction of theory for surface percolation. We view the protonic conduction process described here for low hydration and previously for high hydration as percolative proton transfer along threads of hydrogen-bonded water molecules. A principal element of the percolation picture, which explains the invariance of h(c) to change in pH and solvent, is the sudden appearance of long-range connectivity and infinite clusters at the threshold h(c). The relationship of the protonic conduction threshold to other features of protein hydration is described. The importance of percolative processes for enzyme catalysis and membrane transport is discussed.

  7. About transformation of the deep-water methane bubbles into hydrate powder and hydrate foam

    NASA Astrophysics Data System (ADS)

    Egorov, A. V.; Nigmatulin, R. I.; Rozhkov, A. N.; Sagalevich, A. M.; Chernyaev, E. S.

    2012-04-01

    During the Russian Academy of Sciences "MIRI na Baikale, 2008-2010" expedition, deep-water experiments with the bubbles of methane seeping from the bottom at depths 405, 860 and 1400 meters were carried out. These depths correspond to gas hydrate stability zone. Bubbles were caught by the trap which was looked like an inverted glass. It was found that the behavior of bubbles in a trap depends on the depth. At depth of 405 meters formation of hydrates was not observed. Having got to a trap at the depth of 860 meters, bubbles became covered by solid hydrate envelope, kept the initial form, and after a time period collapsed in a number of hydrate fragments which showed all properties of a granular matter. No visible changes in the hydrate granular matter were observed in the course of lifting it to a depth of 380 meters. Shallower, the decomposition of the hydrate granular matter into methane gas was observed. In the experiments at depth of 1400 meters the caught bubbles, becoming covered by hydrate envelope formed solid hydrate foam in the trap. At lifting this foam structure was deformed slightly but simultaneously a free gas left the foam and filled the trap. The volume of free gas in the trap at lifting varied according to the Boyle-Mariotte law.

  8. Simulation of protonic fluctuations in hydrated protein powders

    NASA Astrophysics Data System (ADS)

    Careri, Giorgio; Milotti, Edoardo

    2003-05-01

    Protons migrating on the surface of weakly hydrated protein powders provide a percolating mesoscopic system which exhibits charge fluctuations near room temperature. In this paper, we describe a simple numerical model where the statistical redistribution of protons on a space distribution of identical side chains lying on a spherical protein surface is varied by random ionization-recombination process to investigate the noise power spectrum of the fluctuating dipole moment, the ergodicity of this system, and the occurrence of localized or extended proton distributions. The case of lysozyme is considered to this end.

  9. Comparative study of protein dynamics in hydrated powders and in solutions: A neutron scattering investigation

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Cornicchi, E.; Onori, G.; Paciaroni, A.

    2008-04-01

    Neutron scattering spectroscopy on a time-of-flight spectrometer has been exploited to reveal the vibrational and relaxational spectral contributions of lysozyme in hydrated powder and solution states. The inelastic component of the dynamical structure factor seems to be quite similar for lysozyme in both the solid- and the liquid-state samples, particularly for energies higher than ˜4 meV. After the subtraction of this component, the quasielastic contribution is evaluated. In the case of hydrated lysozyme powder the quasielastic scattering follows a two-power law with a ballistic Gaussian decrease above ˜2 meV. The quasielastic scattering of lysozyme in solution exhibits a rather similar trend but a much larger intensity. This may be related to the increase of both the number and the amplitudes of the confined diffusive processes related to protein side-chains motions at the protein surface.

  10. Hydration of blended cement pastes containing waste ceramic powder as a function of age

    NASA Astrophysics Data System (ADS)

    Scheinherrová, Lenka; Trník, Anton; Kulovaná, Tereza; Pavlík, Zbyšek; Rahhal, Viviana; Irassar, Edgardo F.; Černý, Robert

    2016-07-01

    The production of a cement binder generates a high amount of CO2 and has high energy consumption, resulting in a very adverse impact on the environment. Therefore, use of pozzolana active materials in the concrete production leads to a decrease of the consumption of cement binder and costs, especially when some type of industrial waste is used. In this paper, the hydration of blended cement pastes containing waste ceramic powder from the Czech Republic and Portland cement produced in Argentina is studied. A cement binder is partially replaced by 8 and 40 mass% of a ceramic powder. These materials are compared with an ordinary cement paste. All mixtures are prepared with a water/cement ratio of 0.5. Thermal characterization of the hydrated blended pastes is carried out in the time period from 2 to 360 days. Simultaneous DSC/TG analysis is performed in the temperature range from 25 °C to 1000 °C in an argon atmosphere. Using this thermal analysis, we identify the temperature, enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates gels dehydration, portlandite, vaterite and calcite decomposition and their changes during the curing time. Based on thermogravimetry results, we found out that the portlandite content slightly decreases with time for all blended cement pastes.

  11. Thermodynamic properties of methane hydrate in quartz powder.

    PubMed

    Voronov, Vitaly P; Gorodetskii, Evgeny E; Safonov, Sergey S

    2007-10-04

    Using the experimental method of precision adiabatic calorimetry, the thermodynamic (equilibrium) properties of methane hydrate in quartz sand with a grain size of 90-100 microm have been studied in the temperature range of 260-290 K and at pressures up to 10 MPa. The equilibrium curves for the water-methane hydrate-gas and ice-methane hydrate-gas transitions, hydration number, latent heat of hydrate decomposition along the equilibrium three-phase curves, and the specific heat capacity of the hydrate have been obtained. It has been experimentally shown that the equilibrium three-phase curves of the methane hydrate in porous media are shifted to the lower temperature and high pressure with respect to the equilibrium curves of the bulk hydrate. In these experiments, we have found that the specific heat capacity of the hydrate, within the accuracy of our measurements, coincides with the heat capacity of ice. The latent heat of the hydrate dissociation for the ice-hydrate-gas transition is equal to 143 +/- 10 J/g, whereas, for the transition from hydrate to water and gas, the latent heat is 415 +/- 15 J/g. The hydration number has been evaluated in the different hydrate conditions and has been found to be equal to n = 6.16 +/- 0.06. In addition, the influence of the water saturation of the porous media and its distribution over the porous space on the measured parameters has been experimentally studied.

  12. Effect of pulverization on hydration kinetic behaviors of creatine anhydrate powders.

    PubMed

    Sakata, Yukoh; Shiraishi, Sumihiro; Otsuka, Makoto

    2004-12-25

    The crystal orientation of creatine monohydrate varies significantly with tableting performance and pulverizing mechanism. Furthermore, the X-ray diffraction patterns of anhydrous forms of untreated creatine monohydrate and of pulverized creatine monohydrate exhibit different crystal orientations. However, hygroscopic forms of unpulverized creatine anhydrate and pulverized creatine anhydrate was exhibit the same diffraction peak pattern. The hygroscopicity of unpulverized and pulverized creatine anhydrate has been investigated by hydration kinetic methods using isothermal differential scanning calorimetry data. Testing of the hygroscopicity of unpulverized and pulverized creatine anhydrate at various levels of relative humidity (RH) at 25 degrees C revealed that the anhydrate was stable at less than 33% RH, but was transformed into the monohydrate at more than 52% RH. Hydration data of unpulverized and pulverized creatine anhydrate at 60% and 75% RH were calculated to determine hydration kinetics using various solid-state kinetic models. The hydration type of unpulverized and pulverized creatine anhydrate powder follows the zero-order mechanism (Polany-Winger equation) R1. The transition rate constant of pulverized creatine anhydrate, calculated from the slope of the straight line, was about 1.34-1.36 times higher than that of unpulverized creatine anhydrate.

  13. Powder formation of {gamma} uranium-molybdenum alloys via hydration-dehydration

    SciTech Connect

    Vaz de Oliveira, Fabio Branco; Durazzo, Michelangelo; Fontenele Urano de Carvalho, Elita; Saliba-Silva, Adonis Marcelo; Gracher Riella, Humberto

    2008-07-15

    Gamma uranium-molybdenum alloys has been considered as fuel phase in plate type fuel elements for MTR reactors, mainly due to their acceptable performance under irradiation and metallurgical processing. To its use as a dispersion phase in aluminum matrix, a necessary step is the conversion of the as cast structure into powder, and one of the techniques considered at IPEN / CNEN - Brazil is HDH (hydration-dehydration). The alloys were produced by the induction melting technique, and samples were obtained from the alloys for the thermal treatments, under constant flow of hydrogen, for temperatures varying from 400 deg C to 600 deg C and times from 1 to 4 hours, followed by dehydration. A preliminary characterization of the powders was made and the curves of mass variation versus time were obtained and related to the powder characteristics. This paper describes the first results on the development of the technology to the powder formation of the (5 to 10) % weight molybdenum {gamma}-UMo alloys, and discusses some of its aspects, mainly those related to the {gamma} {yields} {alpha} equilibrium data. (author)

  14. Time-dependent water dynamics in hydrated uranyl fluoride

    DOE PAGES

    Miskowiec, Andrew J.; Anderson, Brian B.; Herwig, Kenneth W.; ...

    2015-09-15

    In this study, uranyl fluoride is a three-layer, hexagonal structure with significant stacking disorder in the c-direction. It supports a range of unsolved ‘thermodynamic’ hydrates with 0–2.5 water molecules per uranium atom, and perhaps more. However, the relationship between water, hydrate crystal structures, and thermodynamic results, collectively representing the chemical pathway through these hydrate structures, has not been sufficiently elucidated. We used high-resolution quasielastic neutron scattering to study the dynamics of water in partially hydrated uranyl fluoride powder over the course of 4 weeks under closed conditions. The spectra are composed of two quasielastic components: one is associated with translationalmore » diffusive motion of water that is approximately five to six times slower than bulk water, and the other is a slow (on the order of 2–300 ps), spatially bounded water motion. The translational component represents water diffusing between the weakly bonded layers in the crystal, while the bounded component may represent water trapped in subnanometre ‘pockets’ formed by the space between uranium-centred polymerisation units. Complementary neutron diffraction measurements do not show any significant structural changes, suggesting that a chemical conversion of the material does not occur in the thermodynamically isolated system on this timescale.« less

  15. Time-dependent water dynamics in hydrated uranyl fluoride

    SciTech Connect

    Miskowiec, Andrew J.; Anderson, Brian B.; Herwig, Kenneth W.; Huq, Ashfia; Mamontov, Eugene; Rondinone, Adam; Trowbridge, Lee D.

    2015-09-15

    In this study, uranyl fluoride is a three-layer, hexagonal structure with significant stacking disorder in the c-direction. It supports a range of unsolved ‘thermodynamic’ hydrates with 0–2.5 water molecules per uranium atom, and perhaps more. However, the relationship between water, hydrate crystal structures, and thermodynamic results, collectively representing the chemical pathway through these hydrate structures, has not been sufficiently elucidated. We used high-resolution quasielastic neutron scattering to study the dynamics of water in partially hydrated uranyl fluoride powder over the course of 4 weeks under closed conditions. The spectra are composed of two quasielastic components: one is associated with translational diffusive motion of water that is approximately five to six times slower than bulk water, and the other is a slow (on the order of 2–300 ps), spatially bounded water motion. The translational component represents water diffusing between the weakly bonded layers in the crystal, while the bounded component may represent water trapped in subnanometre ‘pockets’ formed by the space between uranium-centred polymerisation units. Complementary neutron diffraction measurements do not show any significant structural changes, suggesting that a chemical conversion of the material does not occur in the thermodynamically isolated system on this timescale.

  16. From powder to solution: hydration dependence of human hemoglobin dynamics correlated to body temperature.

    PubMed

    Stadler, A M; Digel, I; Embs, J P; Unruh, T; Tehei, M; Zaccai, G; Büldt, G; Artmann, G M

    2009-06-17

    A transition in hemoglobin (Hb), involving partial unfolding and aggregation, has been shown previously by various biophysical methods. The correlation between the transition temperature and body temperature for Hb from different species, suggested that it might be significant for biological function. To focus on such biologically relevant human Hb dynamics, we studied the protein internal picosecond motions as a response to hydration, by elastic and quasielastic neutron scattering. Rates of fast diffusive motions were found to be significantly enhanced with increasing hydration from fully hydrated powder to concentrated Hb solution. In concentrated protein solution, the data showed that amino acid side chains can explore larger volumes above body temperature than expected from normal temperature dependence. The body temperature transition in protein dynamics was absent in fully hydrated powder, indicating that picosecond protein dynamics responsible for the transition is activated only at a sufficient level of hydration. A collateral result from the study is that fully hydrated protein powder samples do not accurately describe all aspects of protein picosecond dynamics that might be necessary for biological function.

  17. From Powder to Solution: Hydration Dependence of Human Hemoglobin Dynamics Correlated to Body Temperature

    PubMed Central

    Stadler, A.M.; Digel, I.; Embs, J.P.; Unruh, T.; Tehei, M.; Zaccai, G.; Büldt, G.; Artmann, G.M.

    2009-01-01

    Abstract A transition in hemoglobin (Hb), involving partial unfolding and aggregation, has been shown previously by various biophysical methods. The correlation between the transition temperature and body temperature for Hb from different species, suggested that it might be significant for biological function. To focus on such biologically relevant human Hb dynamics, we studied the protein internal picosecond motions as a response to hydration, by elastic and quasielastic neutron scattering. Rates of fast diffusive motions were found to be significantly enhanced with increasing hydration from fully hydrated powder to concentrated Hb solution. In concentrated protein solution, the data showed that amino acid side chains can explore larger volumes above body temperature than expected from normal temperature dependence. The body temperature transition in protein dynamics was absent in fully hydrated powder, indicating that picosecond protein dynamics responsible for the transition is activated only at a sufficient level of hydration. A collateral result from the study is that fully hydrated protein powder samples do not accurately describe all aspects of protein picosecond dynamics that might be necessary for biological function. PMID:19527667

  18. In situ neutron powder diffraction investigation of the hydration of tricalcium aluminate in the presence of gypsum

    SciTech Connect

    Hartman, M.R. . E-mail: michael.hartman@nist.gov; Berliner, R.

    2005-11-15

    The hydration of a 1:3 molar ratio of tricalcium aluminate, Ca{sub 3}Al{sub 2}O{sub 6}, to gypsum, CaSO{sub 4}.2D{sub 2}O, was investigated at temperatures of 25, 50, and 80 deg. C using time-of-flight powder neutron diffraction combined with multiphase Rietveld structural refinement. It was shown that ettringite, Ca{sub 6}[Al(OD){sub 6}]{sub 2}(SO{sub 4}){sub 3}.{approx}26D{sub 2}O, was the first and only hydration product of the system, in contrast to a prior investigation which suggested the occurrence of a precursor phase prior to the formation of ettringite. Kinetics data showed that the hydration reaction is very sensitive to temperature: hydration at 25 deg. C was characterized by a single kinetic regime while hydration at higher temperatures consisted of two distinct kinetic regimes. The presence of two kinetic regimes was attributed to a change in either the dimensionality of the growth process or a change in the rate controlling mechanism in the hydration reaction.

  19. Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

    SciTech Connect

    Everett, Susan M; Rawn, Claudia J; Keffer, David J.; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy Joe

    2013-01-01

    Gas hydrates are known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice termed self-preservation or anomalous preservation. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Two regions of slowed decomposition for methane hydrate, 180 200 K and 230 260 K, were observed, and the kinetics were studied by in situ low temperature x-ray powder diffraction. The kinetic constants for ice formation from methane hydrate were determined by the Avrami model within each region and activation energies, Ea, were determined by the Arrhenius plot. Ea determined from the data for 180 200 K was 42 kJ/mol and for 230 260 K was 22 kJ/mol. The higher Ea in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  20. The particle size effect on Gas Hydrate Formation in powdered silica particles

    NASA Astrophysics Data System (ADS)

    Kawasaki, T.; Lu, H.; Ripmeester, J. A.; Zeng, H.; Fujii, T.; Nakamizu, M.

    2007-12-01

    Based on the investigations in the past years, it has been recognized that methane hydrates in Nankai Trough primarily occur in turbidite sediments (Fujii et al. 2005; Uchida et al., 2005). Turbidite is composed of a set of sediments, generally becoming finer upward in particle size, from coarse sand to clay (Bouma, 1962). In natural environment the formation of methane hydrate will be inevitably subject to the influence of sediments, so the modes of gas hydrate formation and occurrence might be different in the sediments with various particle sizes and mineral compositions. The elucidation of this issue, how sediments affect methane hydrate formation and occurrence will help in efficient hydrate exploration, accurate estimation of hydrate reserve, and the design of hydrate production method. In this research, we especially studied the particle size effect on the water conversion degree to hydrate using a set of powdered silica particles with the size from medium silt (<20 μm) to medium sand (250 ~ 500 μm). The test specimens were saturated with 3.5% NaCl solution, simulating the interstitial water of marine sediments, and reacted with methane gas at the pressure of ~ 10 MPa and temperature of 3° C. The water conversion degree to hydrate in a test specimen was estimated with the amount of gas that was clathrated in hydrate. The obtained results indicate a clear relationship between water conversion degree to hydrate and particle size: only 3.2 % when particle size is <20 μm, increasing dramatically from 5.7% to 82.8 % when particle size changes from ~30 μm (coarse silt) to ~200 μm (fine sand), and almost stable at ~ 80% when particle size is > 250 μm (medium sand). Because the test materials are all silica, the difference in water conversion degree to hydrate should be resulted from physical properties of silica particle, specific surface area, and/or the property confined by silica particle, pore size. This study was carried out as a part of Research

  1. Neutron powder diffraction studies as a function of temperature of structure II hydrate formed from propane

    USGS Publications Warehouse

    Rawn, C.J.; Rondinone, A.J.; Chakoumakos, B.C.; Circone, S.; Stern, L.A.; Kirby, S.H.; Ishii, Y.

    2003-01-01

    Neutron powder diffraction data confirm that hydrate samples synthesized with propane crystallize as structure type II hydrate. The structure has been modeled using rigid-body constraints to describe C3H8 molecules located in the eight larger polyhedral cavities of a deuterated host lattice. Data were collected at 12, 40, 100, 130, 160, 190, 220, and 250 K and used to calculate the thermal expansivity from the temperature dependence of the lattice parameters. The data collected allowed for full structural refinement of atomic coordinates and the atomic-displacement parameters.

  2. Hydration Characteristics of Low-Heat Cement Substituted by Fly Ash and Limestone Powder

    PubMed Central

    Kim, Si-Jun; Yang, Keun-Hyeok; Moon, Gyu-Don

    2015-01-01

    This study proposed a new binder as an alternative to conventional cement to reduce the heat of hydration in mass concrete elements. As a main cementitious material, low-heat cement (LHC) was considered, and then fly ash (FA), modified FA (MFA) by vibrator mill, and limestone powder (LP) were used as a partial replacement of LHC. The addition of FA delayed the induction period at the hydration heat curve and the maximum heat flow value (qmax) increased compared with the LHC based binder. As the proportion and fineness of the FA increased, the induction period of the hydration heat curve was extended, and the qmax increased. The hydration production of Ca(OH)2 was independent of the addition of FA or MFA up to an age of 7 days, beyond which the amount of Ca(OH)2 gradually decreased owing to their pozzolanic reaction. In the case of LP being used as a supplementary cementitious material, the induction period of the hydration heat curve was reduced by comparison with the case of LHC based binder, and monocarboaluminate was observed as a hydration product. The average pore size measured at an age of 28 days was smaller for LHC with FA or MFA than for 100% LHC. PMID:28793538

  3. The role of the confined water in the dynamic crossover of hydrated lysozyme powders.

    PubMed

    Kurzweil-Segev, Y; Greenbaum Gutina, A; Popov, I; Golodnitsky, D; Feldman, Yu

    2016-04-28

    Water is of fundamental importance for life since it plays a critical role in biological systems. An organism can only function if its macromolecules and other bioactive molecules are hydrated. However, currently there is a gap in the understanding of how protein interfaces affect water's structure and properties. This work presents combined dielectric and calorimetric measurements of hydrated lysozyme powders with different levels of hydration in a broad temperature interval. We chose lysozyme as a test sample since this globular protein has a well-defined pore with an active hydrophilic center inside. Based on the dielectric and calorimetric tests it was shown that a water quasi-solution, which contains the protein residues, has a glass transition temperature at around 155 ± 3 K. The water confined in the pore of the active center of the lysozyme has its melting temperature at around 186 ± 3 K. Melting of confined water is believed to liberate the internal motions of protein macromolecules.

  4. Neutron Powder Diffraction Study of CO2 Hydrate as a Function of Pressure

    NASA Astrophysics Data System (ADS)

    Rawn, C. J.; Chakoumakos, B. C.; Garlea, O.; Leeman, J. R.; Alford, J.; Elwood-Madden, M.; Phelps, T. J.

    2009-12-01

    A sample of structure type I gas hydrate was synthesized from pressuring D2O ice with CO2 and was subsequently studied at high pressure by neutron powder diffraction. Once the sample was loaded into a previously cooled TiZr null scattering pressure cell, the sample was pressurized to 0.1 kbar using He gas and was subsequently cooled to 225 K. Data were collected first at 0.1 kbar and then the cell was pressurized to 1 kbar while holding the temperature constant. Subsequent pressures for data collection were obtained by releasing pressure from the cell. The lattice parameters have been refined from the data using the Rietveld method and between 0.1 and 0.7 kbar the unit cell decreased in a linear fashion with a fairly large negative slope, however, between 0.7 and 1 kbar the unit cell changes are negligible and the slope becomes flat. A second sample was studied at ambient pressure and 175 K and initially showed a large amount of solid CO2 and a small amount of ice along with the CO2 hydrate, however, over time the solid CO2 decreased as it sublimed at that temperature. The average lattice parameter from ten data sets collected at this temperature was 11.890(4) Å agreeing well with previously reported lattice parameters. ACKNOWLEDGMENTS This work is sponsored by the Office of Fossil Energy under Field Work Proposal FEAB111 and access to Oak Ridge National Laboratory's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences. Oak Ridge National Laboratory is managed by UT-Battelle LLC, for the U.S. Department of Energy.

  5. Quil A-lipid powder formulations releasing ISCOMs and related colloidal structures upon hydration.

    PubMed

    Demana, Patrick H; Davies, Nigel M; Hook, Sarah; Rades, Thomas

    2005-03-02

    The aim of the present study was to prepare solid Quil A-cholesterol-phospholipid formulations (as powder mixtures or compressed to pellets) by physical mixing or by freeze-drying of aqueous dispersions of these components in ratios that allow spontaneous formation of ISCOMs and other colloidal structures upon hydration. The effect of addition of excess cholesterol to the lipid mixtures on the release of a model antigen (PE-FITC-OVA) from the pellets was also investigated. Physical properties were evaluated by X-ray powder diffractometry (XPRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and polarized light microscopy (PLM). Characterization of aqueous colloidal dispersions was performed by negative staining transmission electron microscopy (TEM). Physically mixed powders (with or without PE-FITC-OVA) and pellets prepared from the same powders did not spontaneously form ISCOM matrices and related colloidal structures such as worm-like micelles, ring-like micelles, lipidic/layered structures and lamellae (hexagonal array of ring-like micelles) upon hydration as expected from the pseudo-ternary diagram for aqueous mixtures of Quil A, cholesterol and phospholipid. In contrast, spontaneous formation of the expected colloids was demonstrated for the freeze-dried lipid mixtures. Pellets prepared by compression of freeze-dried powders released PE-FITC-OVA slower than those prepared from physically mixed powders. TEM investigations revealed that the antigen was released in the form of colloidal particles (ISCOMs) from pellets prepared by compression of freeze-dried powders. The addition of excess cholesterol slowed down the release of antigen. The findings obtained in this study are important for the formulation of solid Quil A-containing lipid articles as controlled particulate adjuvant containing antigen delivery systems.

  6. In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

    SciTech Connect

    Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E.R.; Fauth, F.; Aranda, M.A.G.; De la Torre, A.G.

    2014-02-15

    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ∼ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′{sub H}-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ∼ 25% at 1 h) than in the active-BCSA one (α ∼ 10% at 1 h), with differences in the crystallization of ettringite (α ∼ 30% and α ∼ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail. -- Highlights: •Belite calcium sulfoaluminate cements early hydration mechanism has been determined. •Belite hydration strongly depends on availability of aluminum hydroxide. •Orthorhombic ye’elimite dissolved at a higher pace than cubic one. •Ye’elimite larger reaction degree yields stratlingite formation by belite reaction. •Rietveld method quantified gypsum, anhydrite and bassanite dissolution rates.

  7. Kinetics of methane hydrate decomposition studied via in situ low temperature X-ray powder diffraction.

    PubMed

    Everett, S Michelle; Rawn, Claudia J; Keffer, David J; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy J

    2013-05-02

    Gas hydrate is known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Based on results from the decomposition of three nominally similar methane hydrate samples, the kinetics of two regions, 180-200 and 230-260 K, within the overall decomposition range 140-260 K, were studied by in situ low temperature X-ray powder diffraction. The kinetic rate constants, k(a), and the reaction mechanisms, n, for ice formation from methane hydrate were determined by the Avrami model within each region, and activation energies, E(a), were determined by the Arrhenius plot. E(a) determined from the data for 180-200 K was 42 kJ/mol and for 230-260 K was 22 kJ/mol. The higher E(a) in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  8. Hydration mechanisms of ternary Portland cements containing limestone powder and fly ash

    SciTech Connect

    De Weerdt, K.; Haha, M. Ben; Le Saout, G.; Kjellsen, K.O.; Justnes, H.; Lothenbach, B.

    2011-03-15

    The effect of minor additions of limestone powder on the properties of fly ash blended cements was investigated in this study using isothermal calorimetry, thermogravimetry (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques, and pore solution analysis. The presence of limestone powder led to the formation of hemi- and monocarbonate and to a stabilisation of ettringite compared to the limestone-free cements, where a part of the ettringite converted to monosulphate. Thus, the presence of 5% of limestone led to an increase of the volume of the hydrates, as visible in the increase in chemical shrinkage, and an increase in compressive strength. This effect was amplified for the fly ash/limestone blended cements due to the additional alumina provided by the fly ash reaction.

  9. Precondition of time required for the generation of methane hydrate

    NASA Astrophysics Data System (ADS)

    Rezničák, Štefan; Malcho, Milan; Siažik, Ján

    2016-06-01

    The paper deals with methane hydrates generated from natural gas. Methane hydrates in nature. Thermobaric conditions necessary for their generation from the natural gas, composition of december 2015 from the company SPP - distribúcia, a.s. It deals with the estimated time of their formation, at a constant pressures of 5, 10 and 15 MPa and at different subcooling temperature. Determination the temperature required for the generation of methane hydrates at these pressures and temperature range based on the equation from research by Kim et. al..

  10. A Circuit Model of Real Time Human Body Hydration.

    PubMed

    Asogwa, Clement Ogugua; Teshome, Assefa K; Collins, Stephen F; Lai, Daniel T H

    2016-06-01

    Changes in human body hydration leading to excess fluid losses or overload affects the body fluid's ability to provide the necessary support for healthy living. We propose a time-dependent circuit model of real-time human body hydration, which models the human body tissue as a signal transmission medium. The circuit model predicts the attenuation of a propagating electrical signal. Hydration rates are modeled by a time constant τ, which characterizes the individual specific metabolic function of the body part measured. We define a surrogate human body anthropometric parameter θ by the muscle-fat ratio and comparing it with the body mass index (BMI), we find theoretically, the rate of hydration varying from 1.73 dB/min, for high θ and low τ to 0.05 dB/min for low θ and high τ. We compare these theoretical values with empirical measurements and show that real-time changes in human body hydration can be observed by measuring signal attenuation. We took empirical measurements using a vector network analyzer and obtained different hydration rates for various BMI, ranging from 0.6 dB/min for 22.7 [Formula: see text] down to 0.04 dB/min for 41.2 [Formula: see text]. We conclude that the galvanic coupling circuit model can predict changes in the volume of the body fluid, which are essential in diagnosing and monitoring treatment of body fluid disorder. Individuals with high BMI would have higher time-dependent biological characteristic, lower metabolic rate, and lower rate of hydration.

  11. A novel method for deriving true density of pharmaceutical solids including hydrates and water-containing powders.

    PubMed

    Sun, Changquan Calvin

    2004-03-01

    True density is commonly measured using helium pycnometry. However, most water-containing powders, for example, hydrates, amorphous drugs and excipients, and most tablet formulations, release water when exposed to a dry helium atmosphere. Because released water brings significant errors to the measured true density and drying alters the nature of water-containing solids, the helium pycnometry is not suitable for those substances. To overcome this problem, a novel method has been developed to accurately calculate powder true density from compaction data. No drying treatment of powder samples is required. Consequently, the true density thus obtained is relevant to tableting characterization studies because no alteration to the solid is induced by drying. This method involves nonlinear regression of compaction pressure-tablet density data based on a modified Heckel equation. When true density values of water-free powders derived by this novel method were plotted against values measured using pycnometry, a regression line with slope close to unity and intercept close to zero was obtained. Thus, the validity of this method was supported. Using this new method, it was further demonstrated that helium pycnometry always overestimates true densities of water containing powders, for example, hydrates, microcrystalline cellulose (MCC), and tablet formulations. The calculated true densities of powders were the same for different particle shapes and sizes of each material. This further suggests that true density values calculated using this novel method are characteristic of given materials and independent of particulate properties. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association

  12. Early age hydration and pozzolanic reaction in natural zeolite blended cements: Reaction kinetics and products by in situ synchrotron X-ray powder diffraction

    SciTech Connect

    Snellings, R.; Mertens, G.; Cizer, O.; Elsen, J.

    2010-12-15

    The in situ early-age hydration and pozzolanic reaction in cements blended with natural zeolites were investigated by time-resolved synchrotron X-ray powder diffraction with Rietveld quantitative phase analysis. Chabazite and Na-, K-, and Ca-exchanged clinoptilolite materials were mixed with Portland cement in a 3:7 weight ratio and hydrated in situ at 40 {sup o}C. The evolution of phase contents showed that the addition of natural zeolites accelerates the onset of C{sub 3}S hydration and precipitation of CH and AFt. Kinetic analysis of the consumption of C{sub 3}S indicates that the enveloping C-S-H layer is thinner and/or less dense in the presence of alkali-exchanged clinoptilolite pozzolans. The zeolite pozzolanic activity is interpreted to depend on the zeolite exchangeable cation content and on the crystallinity. The addition of natural zeolites alters the structural evolution of the C-S-H product. Longer silicate chains and a lower C/S ratio are deduced from the evolution of the C-S-H b-cell parameter.

  13. Investigation of phonon-like excitation in hydrated protein powders by neutron scattering

    NASA Astrophysics Data System (ADS)

    Chu, Xiang-Qiang (Rosie); Mamontov, Eugene; O'Neill, Hugh; Zhang, Qiu; Kolesnikov, Alexander

    2013-03-01

    Detecting the phonon dispersion relations in proteins is essential for understanding the intra-protein dynamical behavior. Such study has been attempted by X-ray in recent years. However, for such detections, neutrons have significant advantages in resolution and time-efficiency compare to X-rays. Traditionally the collective motions of atoms in protein molecules are hard to detect using neutrons, because of high incoherent scattering background from intrinsic hydrogen atoms in the protein molecules. The recent availability of a fully deuterated green fluorescent protein (GFP) synthesized by the Bio-deuteration Lab at ORNL opens new possibilities to probe collective excitations in proteins using inelastic neutron scattering. Using a direct time-of-flight Fermi chopper neutron spectrometer, we obtained a full map of the meV phonon-like excitations in the fully deuterated protein. The Q range of the observed excitations corresponds to the length scale close to the size of the secondary structures of proteins and reflects the collective intra-protein motions. Our results show that hydration of GFP seems to harden, not soften, the collective motions. This result is counterintuitive but in agreement with the observations by previous neutron scattering experiments. Sample preparation was supported by facilities operated by the Center for Structural Molecular Biology at ORNL which is supported by the U.S. DOE, Office of Science, Office of Biological and Environmental Research Project ERKP291.

  14. Effect of Protein-Lipid-Salt Interactions on Sodium Availability in the Mouth and Consequent Perception of Saltiness: As Affected by Hydration in Powders.

    PubMed

    Yucel, Umut; Peterson, Devin G

    2015-09-02

    There is a broad need to reformulate lower sodium food products without affecting their original taste. The present study focuses on characterizing the role of protein-salt interactions on the salt release in low-moisture systems and saltiness perception during hydration. Sodium release from freeze-dried protein powders and emulsion powders formulated at different protein/lipid ratios (5:0 to 1:4) were characterized using a chromatography column modified with a porcine tongue. Emulsion systems with protein structured at the interface were found to have faster initial sodium release rates and faster hydration and were perceived to have a higher initial salt intensity with a lower salty aftertaste. In summary, exposure of the hydrophilic segments of the interface-structured proteins in emulsions was suggested to facilitate hydration and release of sodium during dissolution of low-moisture powder samples.

  15. Influence of hydration and annealing on structure, PSL yield and spatial resolution of pressed powder imaging plates of the X-ray storage phosphor CsBr:Eu2+

    NASA Astrophysics Data System (ADS)

    Kersting, E.; von Seggern, H.

    2017-08-01

    A new production route for europium doped cesium bromide (CsBr:Eu2+) imaging plates has been developed, synthesizing CsBr:Eu2+ powder from a precipitation reaction of aqueous CsBr solution with ethanol. This new route allows the control of features like homogeneous grain size and grain shape of the obtained powder. After drying and subsequent compacting the powder, disk-like samples were fabricated, and their resulting photostimulated luminescence (PSL) properties like yield and spatial resolution were determined. It will be shown that hydration of such disks causes the CsBr:Eu2+ powder to recrystallize starting from the humidity exposed surfaces to the sample interior up to a completely polycrystalline sample resulting in a decreasing PSL yield and an increasing resolution. Subsequent annealing leads to grain refinement combined with a large PSL yield increment and a minor effect on the spatial resolution. By first annealing the "as made" disk, one observes a strong increment of the PSL yield and almost no effect on the spatial resolution. During subsequent hydration, the recrystallization is hindered by minor structural changes of the grains. The related PSL yield drops slightly with increasing hydration time, and the spatial resolution drops considerably. The obtained PSL properties with respect to structure will be discussed with a simple model.

  16. Pre-exercise glycerol hydration improves cycling endurance time

    NASA Technical Reports Server (NTRS)

    Montner, P.; Stark, D. M.; Riedesel, M. L.; Murata, G.; Robergs, R.; Timms, M.; Chick, T. W.

    1996-01-01

    The effects of glycerol ingestion (GEH) on hydration and subsequent cycle ergometer submaximal load exercise were examined in well conditioned subjects. We hypothesized that GEH would reduce physiologic strain and increase endurance. The purpose of Study I (n = 11) was to determine if pre-exercise GEH (1.2 gm/kg glycerol in 26 ml/kg solution) compared to pre-exercise placebo hydration (PH) (26 ml/kg of aspartame flavored water) lowered heart rate (HR), lowered rectal temperature (Tc), and prolonged endurance time (ET) during submaximal load cycle ergometry. The purpose of Study II (n = 7) was to determine if the same pre-exercise regimen followed by carbohydrate oral replacement solution (ORS) during exercise also lowered HR, Tc, and prolonged ET. Both studies were double-blind, randomized, crossover trials, performed at an ambient temperature of 23.5-24.5 degrees C, and humidity of 25-27%. Mean HR was lower by 2.8 +/- 0.4 beats/min (p = 0.05) after GEH in Study I and by 4.4 +/- 1.1 beats/min (p = 0.01) in Study II. Endurance time was prolonged after GEH in Study I (93.8 +/- 14 min vs. 77.4 +/- 9 min, p = 0.049) and in Study II (123.4 +/- 17 min vs. 99.0 +/- 11 min, p = 0.03). Rectal temperature did not differ between hydration regimens in both Study I and Study II. Thus, pre-exercise glycerol-enhanced hyperhydration lowers HR and prolongs ET even when combined with ORS during exercise. The regimens tested in this study could potentially be adapted for endurance activities.

  17. Pre-exercise glycerol hydration improves cycling endurance time

    NASA Technical Reports Server (NTRS)

    Montner, P.; Stark, D. M.; Riedesel, M. L.; Murata, G.; Robergs, R.; Timms, M.; Chick, T. W.

    1996-01-01

    The effects of glycerol ingestion (GEH) on hydration and subsequent cycle ergometer submaximal load exercise were examined in well conditioned subjects. We hypothesized that GEH would reduce physiologic strain and increase endurance. The purpose of Study I (n = 11) was to determine if pre-exercise GEH (1.2 gm/kg glycerol in 26 ml/kg solution) compared to pre-exercise placebo hydration (PH) (26 ml/kg of aspartame flavored water) lowered heart rate (HR), lowered rectal temperature (Tc), and prolonged endurance time (ET) during submaximal load cycle ergometry. The purpose of Study II (n = 7) was to determine if the same pre-exercise regimen followed by carbohydrate oral replacement solution (ORS) during exercise also lowered HR, Tc, and prolonged ET. Both studies were double-blind, randomized, crossover trials, performed at an ambient temperature of 23.5-24.5 degrees C, and humidity of 25-27%. Mean HR was lower by 2.8 +/- 0.4 beats/min (p = 0.05) after GEH in Study I and by 4.4 +/- 1.1 beats/min (p = 0.01) in Study II. Endurance time was prolonged after GEH in Study I (93.8 +/- 14 min vs. 77.4 +/- 9 min, p = 0.049) and in Study II (123.4 +/- 17 min vs. 99.0 +/- 11 min, p = 0.03). Rectal temperature did not differ between hydration regimens in both Study I and Study II. Thus, pre-exercise glycerol-enhanced hyperhydration lowers HR and prolongs ET even when combined with ORS during exercise. The regimens tested in this study could potentially be adapted for endurance activities.

  18. Time resolved fluorescence of cow and goat milk powder

    NASA Astrophysics Data System (ADS)

    Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

    2017-01-01

    Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

  19. Addressing Factors that Control Near-Surface Gas Hydrate Stability with Time-Series Measurements

    NASA Astrophysics Data System (ADS)

    Lapham, L.; Wilson, R. M.; Chanton, J.; Riedel, M.

    2015-12-01

    Gas hydrates are sensitive to pressure and temperature changes, based on their thermodynamic properties. In nature, this translates to changes in sealevel and/or ocean water temperature fluctuations. When hydrates outcrop the seafloor, however, they could also be sensitive to physical disturbances, such as earthquakes, and microbial processes (such as sulfate reduction and/or methane oxidation), both of which could lead to their dissolution. To address these factors controlling hydrate stability, we will present in situ methane, sulfate, and chloride concentrations over time, in pore-waters of shallow sediments near gas hydrates in seep systems. Datasets presented will include one 4-month time series from the Northern Gulf of Mexico, Mississippi Canyon 118, and two 9-month records from offshore Vancouver Island, Barkley Canyon and Bubbly Gulch at Bullseye Vent. We will address the following questions: Does regional scale oceanography affect methane flux from the hydrate-containing sediments, are microbial processes playing a role in hydrate stability, and what are in situ hydrate dissolution rates? We will also discuss challenges faced with collecting such data, and ways to move forward. We will show that in some systems, methane is nearly saturated within a few cm of the overlying water, thus stabilizing the hydrate. Yet in other systems, methane is undersaturated with respect to methane hydrate which suggests hydrates will dissolve. We will also present laboratory rates of hydrate dissolution to compare to those gained from the field.

  20. Time domain NMR as a new process monitoring method for characterization of pharmaceutical hydrates.

    PubMed

    Schumacher, Stefanie Ulrike; Rothenhäusler, Benno; Willmann, Alf; Thun, Jürgen; Moog, Regina; Kuentz, Martin

    2017-04-15

    Hydrates are of great pharmaceutical relevance and even though they have been characterized thoroughly by various analytical techniques, there is barely literature available on molecular mobility of the hydrate water studied by NMR relaxation in the time domain. The aim of this work was to examine the possibility of differentiating hydration states of drugs by (1)H time domain NMR (TD-NMR) regarding spin-spin and spin-lattice relaxation times (T2 and T1) using benchtop equipment. Caffeine and theophylline were selected as model compounds and binary mixtures of hydrate to anhydrate were analyzed for each drug using a spin echo and inversion recovery pulse sequence. It was possible to extract a signal that was specific for the water in the hydrates so that differentiation from anhydrous solid forms was enabled. Excellent calibrations were obtained for quantitative analysis of hydrate/anhydrate mixtures and predicted water contents were in good agreement with water amounts determined in desiccator sorption experiments. TD-NMR was therefore found to be a suitable new technique to characterize pharmaceutical hydrates in a non-invasive and hence sample-sparing manner. Quantification of the hydrate content in pharmaceutical mixtures appears highly attractive for product development and process monitoring. TD-NMR provides here a valuable and complementary technique to established process analytics, such as for example Raman spectroscopy. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Synthesis of Submicron Silver Powder by the Hydrometallurgical Reduction of Silver Nitrate with Hydrazine Hydrate and a Thermodynamic Analysis of the System

    NASA Astrophysics Data System (ADS)

    Ghosh, Dinabandhu; Dasgupta, Samudra

    2008-02-01

    A silver powder of submicron size was produced from the aqueous solutions of its compounds. The silver compounds tried out were silver nitrate and silver oxide, and the reducing agents employed were dimethyl formamide (DMF), hydrazine hydrate, and sodium azide. The solvent mediums were distilled water for the reductions with DMF and sodium azide, and a 2:1 (by volume) mixture of distilled water and ethanol for the reductions with hydrazine hydrate. Of the three reductants, hydrazine hydrate (N2H4·H2O) alone was successful in reducing both the silver compounds to a submicron (<500 nm) metallic silver powder, as revealed by X-ray diffraction (XRD) studies and scanning electron microscopy (SEM) analyses. Additionally, the thermodynamic equilibrium of the system AgNO3-N2H4·H2O in the water ethanol mixture (2:1) was studied at 298 K; the equilibrium constant data so generated was found to compare very well with those derived from the established data of enthalpies and free energies of formation, and half-cell potentials. The following activity coefficient (Raoultian) composition relationship for hydrazine hydrate in its dilute solution in water (plus ethanol) at 298 K is proposed: ln (γ_{{{text{N}_2text{H}_4}}{text{.H}_2text{O}}} ) = 1862( ± 371) - 2055( ± 424)(1 - X_{{{text{N}_2text{H}_4 \\cdot text{H}_2text{O}}}} )2

  2. A combined solid-state NMR and synchrotron x-ray diffraction powder study on the structure of the antioxidant(+)-catechin 4.5 hydrate.

    SciTech Connect

    Harper, J. K.; Doebbler, J. A.; Jaccques, E.; Grant, D. M.; Von Dreele, R. B.; Univ. of Utah

    2010-03-10

    Analyses combining X-ray powder diffraction (XRD) and solid-state NMR (SSNMR) data can now provide crystal structures in challenging powders that are inaccessible by traditional methods. The flavonoid catechin is an ideal candidate for these methods, as it has eluded crystallographic characterization despite extensive study. Catechin was first described nearly two centuries ago, and its powders exhibit numerous levels of hydration. Here, synchrotron XRD data provide all heavy-atom positions in (+)-catechin 4.5-hydrate and establish the space group as C2. SSNMR data ({sup 13}C tensor and {sup 1}H/{sup 13}C correlation) complete the conformation by providing catechin's five OH hydrogen orientations. Since 1903, this phase has been erroneously identified as a 4.0 hydrate, but XRD and density data establish that this discrepancy is due to the facile loss of the water molecule located at a Wyckoff special position in the unit cell. A final improvement to heavy-atom positions is provided by a geometry optimization of bond lengths and valence angles with XRD torsion angles held constant. The structural enhancement in this final structure is confirmed by the significantly improved fit of computed {sup 13}C tensors to experimental data.

  3. Physiochemical Characterization of Iodine (V) Oxide: Hydration Rates

    DTIC Science & Technology

    2014-12-15

    differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and powder X‐ray diffraction (PXRD). In addition, the hydration rates...and thermal gravimetric analysis (TGA) ........................................................4 2 Powder X‐ray patterns of various samples of...relative humidity for various amounts of time .................................8 4 Powder X‐ray diffraction recordings displaying the conversion of

  4. Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

    PubMed

    Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

    2010-01-14

    The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

  5. Relative Timing of Phyllosilicate and Hydrated Sulfate Deposition in Eastern Sinus Meridiani

    NASA Astrophysics Data System (ADS)

    Wiseman, S. M.; Beyer, R. A.

    2014-07-01

    Both Fe/Mg phyllosilicates and hydrated sulfates are associated with extensive indurated, layered deposits. We determine the relative timing of alteration. Phyllosilicates appear to be contained within a laterally continuous stratigraphic horizon.

  6. Effect of cement/wood ratios and wood storage conditions on hydration temperature, hydration time, and compressive strength of wood-cement mixtures

    Treesearch

    Andy W.C. Lee; Zhongli Hong; Douglas R. Phillips; Chung-Yun Hse

    1987-01-01

    This study investigated the effect of cement/wood ratios and wood storage conditions on hydration temperature, hydration time, and compressive strength of wood-cement mixtures made from six wood species: southern pine, white oak, southern red oak, yellow-poplar, sweetgum, and hickory. Cement/wood ratios varied from 13/1 to 4/1. Wood storage conditions consisted of air-...

  7. Diffusion Processes in Water on Oxide Surfaces: Quasielastic Neutron Scattering Study of Hydration Water in Rutile Nano-Powder

    SciTech Connect

    Chu, Xiang-Qiang; Ehlers, Georg; Mamontov, Eugene; Podlesnyak, Andrey A; Wang, Wei; Wesolowski, David J

    2011-01-01

    Quasielastic neutron scattering (QENS) was used to investigate the diffusion dynamics of hydration water on the surface of rutile (TiO{sub 2}) nanopowder. The dynamics measurements utilizing two inelastic instruments, a backscattering spectrometer and a disk chopper spectrometer, probed the fast, intermediate, and slow motions of the water molecules on the time scale of picoseconds to more than a nanosecond. We employed a model-independent analysis of the data collected at each value of the scattering momentum transfer to investigate the temperature dependence of several diffusion components. All of the probed components were present in the studied temperature range of 230-320 K, providing, at a first sight, no evidence of discontinuity in the hydration water dynamics. However, a qualitative change in the elastic scattering between 240 and 250 K suggested a surface freezing-melting transition, when the motions that were localized at lower temperatures became delocalized at higher temperatures. On the basis of our previous molecular dynamics simulations of this system, we argue that interpretation of QENS data from such a complex interfacial system requires at least qualitative input from simulations, particularly when comparing results from spectrometers with very different energy resolutions and dynamic ranges.

  8. Molecular Visualization of Methane - Carbon Dioxide Solid Solution in Gas Hydrates by High Resolution Neutron Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Everett, M.; Rawn, C.; Huq, A.; Chakoumakos, B. C.; Phelps, T. J.

    2012-12-01

    The exchange of CO2 for CH4 in natural gas hydrates could produce energy from untapped sources while at the same time sequestering CO2. In addition to the energy and environmental aspects the solid solution of (CH4)1-x(CO2)x 5.75H2O provides a framework inclusion structure that enables the scientific study of how two molecules that differ greatly in their bonding, shape, coordination and molecular weight can influence the structure and properties of the compound and interact with the framework that occludes the molecules. Samples synthesized by cooling liquid water pressurized with either pure CH4 or CO2 or mixtures of the two gases to temperatures where hydrate formation occurs have been studied using high-resolution neutron diffraction. Static images of the nuclear scattering density of the free moving gas molecules have been determined. Cage occupants and occupancies, the volume change of the unit cell and the individual cages based on composition have been determined.

  9. Time- and angle-resolved photoemission spectroscopy of hydrated electrons near a liquid water surface.

    PubMed

    Yamamoto, Yo-ichi; Suzuki, Yoshi-Ichi; Tomasello, Gaia; Horio, Takuya; Karashima, Shutaro; Mitríc, Roland; Suzuki, Toshinori

    2014-05-09

    We present time- and angle-resolved photoemission spectroscopy of trapped electrons near liquid surfaces. Photoemission from the ground state of a hydrated electron at 260 nm is found to be isotropic, while anisotropic photoemission is observed for the excited states of 1,4-diazabicyclo[2,2,2]octane and I- in aqueous solutions. Our results indicate that surface and subsurface species create hydrated electrons in the bulk side. No signature of a surface-bound electron has been observed.

  10. Real-time observation of the destruction of hydration shells under electrochemical force.

    PubMed

    Yamakata, Akira; Soeta, Eiji; Ishiyama, Tatsuya; Osawa, Masatoshi; Morita, Akihiro

    2013-10-09

    Major alteration or even destruction of the hydration shell around interacting molecules and ions in solution is an important process that determines how hydrated substances interact. Therefore, the direct observation of structural changes in hydration shells around solutes in close contact with other solutes or surfaces is important for understanding chemical processes that take place in solution. In the work described in this paper, time-resolved IR absorption measurements were performed to study the interaction of hydrated Na(+) or tetrapropylammonium cation (Pr4N(+)) with a hydrophobic CO-covered Pt surface; the adsorption force between cations and the surface was controlled by using an electrochemical system. We found that the hydrophobic hydration shell of Pr4N(+) is initially stabilized on the hydrophobic surface, but application of a strong force to the cation approaching CO destroys the water layers between them. This process is rather slow, taking a few hundred milliseconds. Hydrophilic Na(+) behaves quite differently from Pr4N(+) due to the different structure of its hydration shell. These experimental results are supported by molecular dynamics simulations.

  11. Characterizing the secondary hydration shell on hydrated myoglobin, hemoglobin, and lysozyme powders by its vitrification behavior on cooling and its calorimetric glass-->liquid transition and crystallization behavior on reheating.

    PubMed Central

    Sartor, G; Hallbrucker, A; Mayer, E

    1995-01-01

    For hydrated metmyoglobin, methemoglobin, and lysozyme powders, the freezable water fraction of between approximately 0.3-0.4 g water/g protein up to approximately 0.7-0.8 g water/g protein has been fully vitrified by cooling at rates up to approximately 1500 K min-1 and the influence of cooling rate characterized by x-ray diffractograms. This vitreous but freezable water fraction started to crystallize at approximately 210 K to cubic ice and at approximately 240 K to hexagonal ice. Measurements by differential scanning calorimetry have shown that this vitreous but freezable water fraction undergoes, on reheating at a rate of 30 K min-1, a glass-->liquid transition with an onset temperature of between approximately 164 and approximately 174 K, with a width of between approximately 9 and approximately 16 degrees and an increase in heat capacity of between approximately 20 and approximately 40 J K-1 (mol of freezable water)-1 but that the glass transition disappears upon crystallization of the freezable water. These calorimetric features are similar to those of water imbibed in the pores of a synthetic hydrogel but very different from those of glassy bulk water. The difference to glassy bulk water's properties is attributed to hydrophilic interaction and H-bonding of the macromolecules' segments with the freezable water fraction, which thereby becomes dynamically modified. Abrupt increase in minimal or critical cooling rate necessary for complete vitrification is observed at approximately 0.7-0.8 g water/g protein, which is attributed to an abrupt increase of water's mobility, and it is remarkably close to the threshold value of water's mobility on a hydrated protein reported by Kimmich et al. (1990, Biophys. J. 58:1183). The hydration level of approximately 0.7-0.8 g water/g protein is approximately that necessary for completing the secondary hydration shell. PMID:8599674

  12. Evaluation of Bioequivalence Between the New Procaterol Hydrochloride Hydrate Dry Powder Inhaler and the Approved Dry Powder Inhaler in Patients With Asthma in a Randomized, Double-Blind, Double-Dummy, Crossover Comparison Study: A Phase 3 Study.

    PubMed

    Shirai, Ryo; Suzaki, Yuki; Sato, Kyoko; Takeuchi, Yuko; Tokimatsu, Issei; Koga, Nobuyuki; Kadota, Junichi; Ohashi, Kyoichi

    2017-09-08

    Procaterol hydrochloride hydrate (procaterol) is a β2 -adrenergic receptor agonist that induces a strong bronchodilatory effect. The procaterol dry powder inhaler (DPI) has been frequently used in patients with bronchial asthma or chronic obstructive pulmonary disease. We evaluated the bioequivalence and safety between the new procaterol DPI (new DPI) and the approved procaterol DPI (approved DPI). This study was a randomized, double-blind, double-dummy, crossover comparison to evaluate the pharmacodynamic equivalence of the new DPI and the approved DPI in patients with bronchial asthma. Primary efficacy variables were area under the concentration-time curve (AUC) forced expiratory volume in the first second (FEV1 )/h and maximum FEV1 during the 480-minute measurement period. Patients were divided into 2 groups, New-DPI-First (n = 8) and Approved-DPI-First (n = 8), according to the investigational medical product that was administered first. Patients inhaled 20 μg of procaterol in each period. FEV1 was measured by a spirometer at predose and at 15, 30, 60, 90, 120, 180, 240, 360, and 480 minutes after each investigational medical product administration. Equivalence was evaluated by confirming that the 2-sided 90%CIs for the difference between the new and the approved DPI in means of AUC (FEV1 )/h and maximum FEV1 were within the acceptance criteria of -0.15 to 0.15 L. The difference in means of AUC (FEV1 )/h and maximum FEV1 was 0.041 L and 0.033 L, respectively, and the 90%CI was 0.004 to 0.078 L and -0.008 to 0.074 L, respectively. These CIs were both within the acceptance criteria. The new DPI was assessed as being bioequivalent to the approved DPI. © 2017 The Authors. Clinical Pharmacology in Drug Development Published by Wiley Periodicals, Inc. on behalf of The American College of Clinical Pharmacology.

  13. Wide-ranging molecular mobilities of water in active pharmaceutical ingredient (API) hydrates as determined by NMR relaxation times.

    PubMed

    Yoshioka, Sumie; Aso, Yukio; Osako, Tsutomu; Kawanishi, Toru

    2008-10-01

    In order to examine the possibility of determining the molecular mobility of hydration water in active pharmaceutical ingredient (API) hydrates by NMR relaxation measurement, spin-spin relaxation and spin-lattice relaxation were measured for the 11 API hydrates listed in the Japanese Pharmacopeia using pulsed (1)H-NMR. For hydration water that has relatively high mobility and shows Lorentzian decay, molecular mobility as determined by spin-spin relaxation time (T(2)) was correlated with ease of evaporation under both nonisothermal and isothermal conditions, as determined by DSC and water vapor sorption isotherm analysis, respectively. Thus, T(2) may be considered a useful parameter which indicates the molecular mobility of hydration water. In contrast, for hydration water that has low mobility and shows Gaussian decay, T(2) was found not to correlate with ease of evaporation under nonisothermal conditions, which suggests that in this case, the molecular mobility of hydration water was too low to be determined by T(2). A wide range of water mobilities was found among API hydrates, from low mobility that could not be evaluated by NMR relaxation time, such as that of the water molecules in pipemidic acid hydrate, to high mobility that could be evaluated by this method, such as that of the water molecules in ceftazidime hydrate. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  14. The time dependence dynamics of hydration water changes upon crossing T*

    NASA Astrophysics Data System (ADS)

    Vasi, S.; Corsaro, C.; Mallamace, D.; Mallamace, F.

    2016-05-01

    We carry out a Nuclear Magnetic Resonance (NMR) spectroscopy study on the dynamics of lysozyme hydration water. We consider a hydration level corresponding to a single water monolayer. We investigate the thermodynamical region from 295K to 355K, at temperatures below and above the "magic" temperature T* ≈ 320{ K} . In particular, we focus our attention on hydration water mean-square displacement (MSD) as a function of the diffusion time at different temperatures. Our results suggest the occurrence of a smooth anomalous diffusion from a sub-diffusive state (T < T^*) to a super-diffusive one (T > T^*) . These conclusions confirm the importance of the temperature T^* as the border for water behavior.

  15. Feasibility of monitoring gas hydrate production with time-lapse VSP

    SciTech Connect

    Kowalsky, M.B.; Nakagawa, S.; Moridis, G.J.

    2009-11-01

    In this work we begin to examine the feasibility of using time-lapse seismic methods-specifically the vertical seismic profiling (VSP) method-for monitoring changes in hydrate accumulations that are predicted to occur during production of natural gas.

  16. Modeling the Potential Volume of Gas Hydrates Over Time and During Transient Climate Events

    NASA Astrophysics Data System (ADS)

    Dickens, G. R.; Dickens, G. R.

    2001-12-01

    Gas hydrates in marine sediment probably serve as a large bacterially mediated capacitor in the global carbon cycle, storing and releasing CH4 with changes in external forcing. Although germinal, models of the global carbon cycle that incorporate gas hydrates require characterization of the available pore space -- the potential volume -- over time, especially during transient climate events. Potentially, gas hydrates can occur between the seafloor and a locus of subbottom depths where geothermal gradients intersect gas-gas hydrate-pore water equilibrium curves. Perpendicular to a given continental margin, the lens shaped area between these two bounding surfaces (Asl) varies according to seven basic parameters: gas composition, water activity (aw), bottom water temperature (Tb), geothermal gradient (G), slope depth (zslb), slope gradient (Z) and sea level relative to the shelf break (zo). Assuming pure CH4 gas, ~35 km2 of sediment can host gas hydrate across an average continental margin at a Pleistocene lowstand (aw = 0.981, Tb = 0° C, G = 0.05° C/m; zslb = 4000 m; Z = 0.04; zo = 0). However, this potential area would decrease with smaller aw, higher Tb, greater G, shallower zslb, steeper Z and lower zo, and increase with opposite external conditions. Of the basic parameters, temperature (Tb and G) and bathymetry (zslb and Z) can particularly influence the distribution of gas hydrate on continental slopes. A hydrothermal gradient (i.e., surface temperatures > Tb) will also decrease Asl, although minimally, especially if Tb exceeds 5° . The sum of parallel cross-sectional areas along a margin combined with porosity (φ ) gives the potential volume of gas hydrate (V). Assuming ~200,000 km of continental margin with φ of 0.50, ~3.5 x 106 km3 of pore space can contain gas hydrates at present-day, a volume that compares favorably with previous estimates (1.2 to 6.4 x 106 km3) although underlying approaches differ fundamentally. Since the Triassic, VGlob probably has

  17. Observation of salt effects on hydration water of lysozyme in aqueous solution using terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Aoki, Katsuyoshi; Shiraki, Kentaro; Hattori, Toshiaki

    2013-10-01

    Terahertz time-domain spectroscopy was used to investigate the salt effect of ammonium sulfate on the dynamics of hydration water of lysozyme in aqueous solution. The absorption coefficient of lysozyme aqueous solutions containing salt was subtracted by that of the water and ammonium sulfate contained in the lysozyme solution. The results revealed that ammonium sulfate increases the absorption coefficient of the hydration water, which indicates that the dynamics of the hydration water becomes faster and/or the number of hydration water molecules decreases with increasing ammonium sulfate concentration.

  18. X-ray CT Observations of Methane Hydrate Distribution Changes over Time in a Natural Sediment Core from the BPX-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well

    SciTech Connect

    Kneafsey, T.J.; Rees, E.V.L.

    2010-03-01

    When maintained under hydrate-stable conditions, methane hydrate in laboratory samples is often considered a stable and immobile solid material. Currently, there do not appear to be any studies in which the long-term redistribution of hydrates in sediments has been investigated in the laboratory. These observations are important because if the location of hydrate in a sample were to change over time (e.g. by dissociating at one location and reforming at another), the properties of the sample that depend on hydrate saturation and pore space occupancy would also change. Observations of hydrate redistribution under stable conditions are also important in understanding natural hydrate deposits, as these may also change over time. The processes by which solid hydrate can move include dissociation, hydrate-former and water migration in the gas and liquid phases, and hydrate formation. Chemical potential gradients induced by temperature, pressure, and pore water or host sediment chemistry can drive these processes. A series of tests were performed on a formerly natural methane-hydrate-bearing core sample from the BPX-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, in order to observe hydrate formation and morphology within this natural sediment, and changes over time using X-ray computed tomography (CT). Long-term observations (over several weeks) of methane hydrate in natural sediments were made to investigate spatial changes in hydrate saturation in the core. During the test sequence, mild buffered thermal and pressure oscillations occurred within the sample in response to laboratory temperature changes. These oscillations were small in magnitude, and conditions were maintained well within the hydrate stability zone.

  19. Preparation and physicochemical characterization of spray-dried and jet-milled microparticles containing bosentan hydrate for dry powder inhalation aerosols

    PubMed Central

    Lee, Hyo-Jung; Kang, Ji-Hyun; Lee, Hong-Goo; Kim, Dong-Wook; Rhee, Yun-Seok; Kim, Ju-Young; Park, Eun-Seok; Park, Chun-Woong

    2016-01-01

    The objectives of this study were to prepare bosentan hydrate (BST) microparticles as dry powder inhalations (DPIs) via spray drying and jet milling under various parameters, to comprehensively characterize the physicochemical properties of the BST hydrate microparticles, and to evaluate the aerosol dispersion performance and dissolution behavior as DPIs. The BST microparticles were successfully prepared for DPIs by spray drying from feeding solution concentrations of 1%, 3%, and 5% (w/v) and by jet milling at grinding pressures of 2, 3, and 4 MPa. The physicochemical properties of the spray-dried (SD) and jet-milled (JM) microparticles were determined via scanning electron microscopy, atomic force microscopy, dynamic light scattering particle size analysis, Karl Fischer titration, surface analysis, pycnometry, differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The in vitro aerosol dispersion performance and drug dissolution behavior were evaluated using an Anderson cascade impactor and a Franz diffusion cell, respectively. The JM microparticles exhibited an irregular corrugated surface and a crystalline solid state, while the SD microparticles were spherical with a smooth surface and an amorphous solid state. Thus, the in vitro aerosol dispersion performance and dissolution behavior as DPIs were considerably different due to the differences in the physicochemical properties of the SD and JM microparticles. In particular, the highest grinding pressures under jet milling exhibited excellent aerosol dispersion performance with statistically higher values of 56.8%±2.0% of respirable fraction and 33.8%±2.3% of fine particle fraction and lower mass median aerodynamic diameter of 5.0±0.3 μm than the others (P<0.05, analysis of variance/Tukey). The drug dissolution mechanism was also affected by the physicochemical properties that determine the dissolution kinetics of the SD and JM microparticles, which were well

  20. Preparation and physicochemical characterization of spray-dried and jet-milled microparticles containing bosentan hydrate for dry powder inhalation aerosols.

    PubMed

    Lee, Hyo-Jung; Kang, Ji-Hyun; Lee, Hong-Goo; Kim, Dong-Wook; Rhee, Yun-Seok; Kim, Ju-Young; Park, Eun-Seok; Park, Chun-Woong

    2016-01-01

    The objectives of this study were to prepare bosentan hydrate (BST) microparticles as dry powder inhalations (DPIs) via spray drying and jet milling under various parameters, to comprehensively characterize the physicochemical properties of the BST hydrate microparticles, and to evaluate the aerosol dispersion performance and dissolution behavior as DPIs. The BST microparticles were successfully prepared for DPIs by spray drying from feeding solution concentrations of 1%, 3%, and 5% (w/v) and by jet milling at grinding pressures of 2, 3, and 4 MPa. The physicochemical properties of the spray-dried (SD) and jet-milled (JM) microparticles were determined via scanning electron microscopy, atomic force microscopy, dynamic light scattering particle size analysis, Karl Fischer titration, surface analysis, pycnometry, differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The in vitro aerosol dispersion performance and drug dissolution behavior were evaluated using an Anderson cascade impactor and a Franz diffusion cell, respectively. The JM microparticles exhibited an irregular corrugated surface and a crystalline solid state, while the SD microparticles were spherical with a smooth surface and an amorphous solid state. Thus, the in vitro aerosol dispersion performance and dissolution behavior as DPIs were considerably different due to the differences in the physicochemical properties of the SD and JM microparticles. In particular, the highest grinding pressures under jet milling exhibited excellent aerosol dispersion performance with statistically higher values of 56.8%±2.0% of respirable fraction and 33.8%±2.3% of fine particle fraction and lower mass median aerodynamic diameter of 5.0±0.3 μm than the others (P<0.05, analysis of variance/Tukey). The drug dissolution mechanism was also affected by the physicochemical properties that determine the dissolution kinetics of the SD and JM microparticles, which were well

  1. Crystal structure of carnidazole form II from synchrotron X-ray powder diffraction: structural comparison with form I, the hydrated form and the low energy conformations in vacuo.

    PubMed

    de Armas, Héctor Novoa; Peeters, Oswald M; Blaton, Norbert; Van den Mooter, Guy; De Ridder, Dirk J A; Schenk, Henk

    2006-10-01

    The crystal structure of carnidazole form II, O-methyl [2-(2-methyl-5-nitro-1H-imidazole-1-yl)ethyl]thiocarbamate, has been determined using synchrotron X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined by the Rietveld method. For structure solution, 12 degrees of freedom were defined: one motion group and six torsions. Form II crystallizes in space group P2(1)/n, Z=4, with unit cell parameters after Rietveld refinement: a=13.915(4), b=8.095(2), c=10.649(3) A, beta=110.83(1) degrees, and V=1121.1(5) A3. The two polymorphic forms, as well as the hydrate, crystallize in the monoclinic space group P2(1)/n having four molecules in the cell. In form II, the molecules are held together by forming two infinite zig-zag chains via hydrogen bonds of the type N--H...N, the same pattern as in form I. A conformational study of carnidazole, at semiempirical PM3 level, was performed using stochastic approaches based on modification of the flexible torsion angles. The values of the torsion angles for the molecules of the two polymorphic forms and the hydrate of carnidazole are compared to those obtained from the conformational search. Form I and form II are enantiotropic polymorphic pairs this agrees with the fact that the two forms are conformational polymorphs.

  2. Raman scattering and X-ray powder diffraction studies of hydrate layered perovskites: dirubidium aquapentafluoromanganate(III) and dipotassium aquapentafluoroferrate(III)

    SciTech Connect

    Galicka, Karolina; Slodczyk, Aneta; Ratuszna, Alicja; Daniel, Philippe; Malecki, Grzegorz

    2004-06-08

    The structural and vibrational properties of above mentioned crystals were determined using X-ray powder diffraction and Raman scattering experiments. At room temperature hydrate layered perovskites: Rb{sub 2}MnF{sub 5}{center_dot}H{sub 2}O and K{sub 2}FeF{sub 5}{center_dot}H{sub 2}O exhibit orthorhombic--Cmcm (D{sub 2h}{sup 17}) and monoclinic--C2/c (C{sub 2h}{sup 6}) symmetry. Their structure is built up of MnF{sub 6} or FeF{sub 5}{center_dot}H{sub 2}O octahedra forming trans-linked zig-zag chains or hydrogen bonded zig-zag chains along the major crystallographic direction [0 0 1], respectively. To confirm crystal structures and to describe lattice dynamics of these compounds the vibrational normal modes (in {gamma} point of first Brillouin zone) were calculated on the base of the group theory analysis and compared with the spectra obtained from Raman scattering experiments. A relatively good reliability was obtained for both X-ray powder diffraction and Raman scattering.

  3. Near infrared spectroscopic calibration models for real time monitoring of powder density.

    PubMed

    Román-Ospino, Andrés D; Singh, Ravendra; Ierapetritou, Marianthi; Ramachandran, Rohit; Méndez, Rafael; Ortega-Zuñiga, Carlos; Muzzio, Fernando J; Romañach, Rodolfo J

    2016-10-15

    Near infrared spectroscopic (NIRS) calibration models for real time prediction of powder density (tap, bulk and consolidated) were developed for a pharmaceutical formulation. Powder density is a critical property in the manufacturing of solid oral dosages, related to critical quality attributes such as tablet mass, hardness and dissolution. The establishment of calibration techniques for powder density is highly desired towards the development of control strategies. Three techniques were evaluated to obtain the required variation in powder density for calibration sets: 1) different tap density levels (for a single component), 2) generating different strain levels in powders blends (and as consequence powder density), through a modified shear Couette Cell, and 3) applying normal forces during a compressibility test with a powder rheometer to a pharmaceutical blend. For each variation in powder density, near infrared spectra were acquired to develop partial least squares (PLS) calibration models. Test samples were predicted with a relative standard error of prediction of 0.38%, 7.65% and 0.93% for tap density (single component), shear and rheometer respectively. Spectra obtained in real time in a continuous manufacturing (CM) plant were compared to the spectra from the three approaches used to vary powder density. The calibration based on the application of different strain levels showed the greatest similarity with the blends produced in the CM plant.

  4. Dynamics of protein hydration water

    NASA Astrophysics Data System (ADS)

    Wolf, M.; Emmert, S.; Gulich, R.; Lunkenheimer, P.; Loidl, A.

    2015-09-01

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water.

  5. Dynamics of protein hydration water.

    PubMed

    Wolf, M; Emmert, S; Gulich, R; Lunkenheimer, P; Loidl, A

    2015-09-01

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water.

  6. An investigation on the influence of milling time and calcination temperature on the characterization of nano cerium oxide powder synthesized by mechanochemical route

    SciTech Connect

    Aminzare, M.; Amoozegar, Z.; Sadrnezhaad, S.K.

    2012-11-15

    Highlights: ► Synthesis of nanosized CeO{sub 2} was carried out using mechanochemical reactions plus sequential calcinations procedure. ► The effect of milling time and calcinations procedure on crystallite size and surface area of the as-synthesized powders was investigated. ► The extended milling times were exposed to result in the smaller crystallite size, and hence higher surface area for the as-synthesized powder. ► Higher calcinations temperatures, on the other hand, led to the as-synthesized powder with a larger crystallite size and therefore, lower surface area. ► Activation energy for nanocrystallite growth was calculated during the calcinations procedure and the aforementioned crystallite growth was found to be conducted in the light of interfacial reactions. -- Abstract: The synthesis of nano-sized CeO{sub 2} powder was investigated via mechanochemical reactions between hydrate cerium chloride and sodium hydroxide as the starting materials. The process was followed by a subsequent calcination procedure. Characterization of as-synthesized powder was performed using X-ray diffraction, FTIR spectroscopy, Brunner–Emmett–Teller (BET) nitrogen gas absorption, scanning electron microscopy (SEM) and particle size analyzer (PSA). The precursors were milled for different milling times and then were subjected to different heat treatment procedure at variable temperatures from 100 to 700 °C. According to the results, milling time and calcination temperatures induce paramountal effects on crystallite size and surface area of as-synthesized powders. In addition, the average activation energy for the growth of nanocrystals during calcination was determined to be about 12.53 kJ/mol, suggesting the influence of interfacial reactions on the crystallite growth during the calcination procedure.

  7. Analysis of black powder by ion mobility-time-of-flight mass spectrometry.

    PubMed

    Crawford, Christina L; Boudries, Hacene; Reda, Ralph J; Roscioli, Kristyn M; Kaplan, Kimberly A; Siems, William F; Hill, Herbert H

    2010-01-01

    Ion mobility-time-of-flight mass spectrometry (IM-TOFMS) was used to identify and correlate response ions associated with three black powder samples by mass and mobility. Vapors produced by thermal desorption of the black powders were ionized by a (63)Ni source; subsequent response ions were separated and identified using IM-TOFMS. The same response ions were found for each black powder regardless of geographic origin. The most intense mass and mobility peaks were attributed to ionic forms of sulfur allotropes ((32)S(n)(-), where n = 1-5). Vapor samples from GOEX black powder were also analyzed by two stand-alone ion mobility spectrometry systems, yielding an average reduced mobility value (K(o)) of 2.28 +/- 0.02 cm(2) V(-1) s(-1) for black powder across all three instruments.

  8. The combined effects of hydration and exercise heat stress on choice reaction time.

    PubMed

    Serwah, N; Marino, F E

    2006-05-01

    The purpose of this investigation was to examine the combined effects of hydration and exercise heat stress on choice reaction time. On three separate occasions eight male subjects performed cycle exercise at approximately 70% of peak power output in warm, humid conditions (31 degrees C, 63% relative humidity) for a maximum of 90 min or until exhaustion. Throughout the trials, subjects ingested either a volume of water equal to fluid loss (100-FR), a volume equivalent to approximately 50% of fluid loss (50-FR), or no fluid (0-FR). A choice reaction time task was undertaken at rest, after 20 min of cycling, 40 min of cycling and at the conclusion of exercise. Mean reaction time for 100-FR was 342.2+/-8.2 ms, 352.4+/-7.5 ms for 50-FR and 345.6+/-8.4 ms for 0-FR and were not significantly different. Choice reaction time was facilitated as the duration of exercise progressed with reaction time at 40 min and conclusion stages of exercise faster than at rest (P<0.005). Choice reaction time and accuracy were affected by the number of choices, with choice reaction time increasing linearly with the number of choices (P<0.005) and rate of incorrect responses increasing in the 4-choice task compared to the 1-choice and 2-choice task (P<0.05). The results indicate that, in up to 90 min of exercise in warm, humid conditions, choice reaction time is not compromised by different levels of hydration.

  9. Effect of Powder Reuse Times on Additive Manufacturing of Ti-6Al-4V by Selective Electron Beam Melting

    NASA Astrophysics Data System (ADS)

    Tang, H. P.; Qian, M.; Liu, N.; Zhang, X. Z.; Yang, G. Y.; Wang, J.

    2015-03-01

    An advantage of the powder-bed-based metal additive manufacturing (AM) processes is that the powder can be reused. The powder reuse or recycling times directly affect the affordability of the additively manufactured parts, especially for the AM of titanium parts. This study examines the influence of powder reuse times on the characteristics of Ti-6Al-4V powder, including powder composition, particle size distribution (PSD), apparent density, tap density, flowability, and particle morphology. In addition, tensile samples were manufactured and evaluated with respect to powder reuse times and sample locations in the powder bed. The following findings were made from reusing the same batch of powder 21 times for AM by selective electron beam melting: (i) the oxygen (O) content increased progressively with increasing reuse times but both the Al content and the V content remained generally stable (a small decrease only); (ii) the powder became less spherical with increasing reuse times and some particles showed noticeable distortion and rough surfaces after being reused 16 times; (iii) the PSD became narrower and few satellite particles were observed after 11 times of reuse; (iv) reused powder showed improved flowability; and (v) reused powder showed no measurable undesired influence on the AM process and the samples exhibited highly consistent tensile properties, irrespective of their locations in the powder bed. The implications of these findings were discussed.

  10. Measuring in situ methane concentrations over time at Gas Hydrate seafloor observatories

    NASA Astrophysics Data System (ADS)

    Lapham, L.; Wilson, R. M.; Chanton, J.; Higley, P.; Lutken, C.; Riedel, M.

    2011-12-01

    Since 2006, we have been working on outfitting Gas Hydrate seafloor observatories with instruments, called Pore-Fluid Arrays, to collect and measure in situ methane concentrations and other biogeochemical parameters over time. The central technology within the PFA's uses OsmoSampler instruments that use osmosis to pull fluids slowly through ports into 300 meter-long copper tubing coil. OsmoSamplers are robust, require no power, and give sample resolution on the order of days to weeks. They allow questions about the dynamics of a system, in our case, gas hydrate systems, to be asked. For example, at the Gulf of Mexico Gas Hydrate Research Consortium monitoring station, we asked "on what time scale do gas hydrates form or decompose?" A 4-month time-series from Mississippi Canyon 118 gave unexpected results showing methane dynamics from the deep-sea influenced by regional tectonic activity. In 2009, we extended this tectonic link to methane release by asking the specific question "is shallow gas released from the seafloor when regional tectonics is active, and, if so, what is the temporal variability of such release events?" To answer this, we deployed a PFA in an area of seafloor where extensive methane venting is known to occur, Northern Cascadia margin gas hydrate sites. This area has seafloor cracks with active bubble streams and thin bacterial mats suggesting shallow gas and possible pore-fluid saturation. One of these gas crack sites, informally named "bubbly gulch", was chosen to deploy a PFA for 9 months. The PFA was modified to be ROV-deployable and was made up of 4 OsmoSamplers that were each plumbed to a port along a 1-meter probe tip using small diameter tubing. Because of the high methane concentrations anticipated, in situ pressures were maintained within the coil by the addition of a high pressure valve. Water samples were collected from the overlying water, at the sediment-water interface, and 6 and 10 cm into the sediments. Bottom water temperatures

  11. Chemical vs. Physical Acceleration of Cement Hydration

    PubMed Central

    Bentz, Dale P.; Zunino, Franco; Lootens, Didier

    2016-01-01

    Cold weather concreting often requires the use of chemical accelerators to speed up the hydration reactions of the cement, so that setting and early-age strength development will occur in a timely manner. While calcium chloride (dihydrate – CaCl2·2H2O) is the most commonly used chemical accelerator, recent research using fine limestone powders has indicated their high proficiency for physically accelerating early-age hydration and reducing setting times. This paper presents a comparative study of the efficiency of these two approaches in accelerating hydration (as assessed via isothermal calorimetry), reducing setting times (Vicat needle), and increasing early-age mortar cube strength (1 d and 7 d). Both the CaCl2 and the fine limestone powder are used to replace a portion of the finest sand in the mortar mixtures, while keeping both the water-to-cement ratio and volume fractions of water and cement constant. Studies are conducted at 73.4 °F (23°C) and 50 °F (10 °C), so that activation energies can be estimated for the hydration and setting processes. Because the mechanisms of acceleration of the CaCl2 and limestone powder are different, a hybrid mixture with 1 % CaCl2 and 20 % limestone powder (by mass of cement) is also investigated. Both technologies are found to be viable options for reducing setting times and increasing early-age strengths, and it is hoped that concrete producers and contractors will consider the addition of fine limestone powder to their toolbox of techniques for assuring performance in cold weather and other concreting conditions where acceleration may be needed. PMID:28077884

  12. A temperature and photographic time-series from a seafloor gas hydrate deposit on the Gulf of Mexico Slope

    NASA Astrophysics Data System (ADS)

    MacDonald, I. R.; Vararo, M.; Bender, L.

    2003-04-01

    Under laboratory conditions, gas hydrates are highly sensitive to changes in water temperature. MacDonald et al. (1994) and Roberts et al. (1999) have monitored in-situ deposits and recorded rapid changes in gas flux from vents partially plugged with gas hydrate; the changes appear to correlate with fluctuation in bottom temperature over ranges of <0.2 to 1.0 C. To study this process in a different way, a monitoring array consisting of a time lapse camera and two thermistor probes was deployed at a hydrocarbon seep known as Bush Hill. Every 6 hours for 96 days (until battery power was exhausted), the camera recorded a digital image of a prominent gas hydrate mound consisting of Structure II hydrate with gas vents, chemosynthetic tube worms, and a number of mobile species. The temperature probes comprised two autonomous Antares thermistors, one at each end of a 50-cm PVC wand, which recorded temperatures with precision of better than 0.1 C at 30-min intervals over 327 d. One probe was implanted with a tight seal into a drill hole about 7 cm deep in the top of the gas hydrate mound. The second was inserted about 50 cm deep into the adjacent sediments. For each probe, the top thermistor recorded the ambient water temperature while the bottom thermistor recorded the internal temperature of the hydrate or sediment. Photographic results show no dramatic changes in the size, shape, or gas venting from the mound during the 96 day time-series. There were subtle increases in the amount of hydrate exposed to the water between the end of the photographic time series and the recovery of the monitoring array. Mean temperatures (SDEV) and temperature range recorded by the probes were as follows: In-water: 7.87 ( 0.44) and 6.64-9.73 C In-hydrate: 7.81 ( 0.34) and 6.87-9.18 C In-sediment: 7.81 ( 0.16) and 7.79-9.18 C Spectra of the temperature records showed significant high-frequency peaks for in-water data corresponding to K1, M2 and M3 lunar tides. Of these peaks, only the K1

  13. Multi-rate time stepping schemes for hydro-geomechanical model for subsurface methane hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Gupta, Shubhangi; Wohlmuth, Barbara; Helmig, Rainer

    2016-05-01

    We present an extrapolation-based semi-implicit multi-rate time stepping (MRT) scheme and a compound-fast MRT scheme for a naturally partitioned, multi-time-scale hydro-geomechanical hydrate reservoir model. We evaluate the performance of the two MRT methods compared to an iteratively coupled solution scheme and discuss their advantages and disadvantages. The performance of the two MRT methods is evaluated in terms of speed-up and accuracy by comparison to an iteratively coupled solution scheme. We observe that the extrapolation-based semi-implicit method gives a higher speed-up but is strongly dependent on the relative time scales of the latent (slow) and active (fast) components. On the other hand, the compound-fast method is more robust and less sensitive to the relative time scales, but gives lower speed up as compared to the semi-implicit method, especially when the relative time scales of the active and latent components are comparable.

  14. Improvement of gas hydrate preservation by increasing compression pressure to simple hydrates of methane, ethane, and propane

    NASA Astrophysics Data System (ADS)

    Kida, Masato; Jin, Yusuke; Watanabe, Mizuho; Murayama, Tetsuro; Nagao, Jiro

    2017-09-01

    In this report, we describe the dissociation behavior of gas hydrate grains pressed at 1 and 6 MPa. Certain simple gas hydrates in powder form show anomalous preservation phenomenon under their thermodynamic unstable condition. Investigation of simple hydrates of methane, ethane, and propane reveals that high pressure applied to the gas hydrate particles enhances their preservation effects. Application of high pressure increases the dissociation temperature of methane hydrate and has a restrictive effect against the dissociation of ethane and propane hydrate grains. These improvements of gas hydrate preservation by increasing pressure to the initial gas hydrate particles imply that appropriate pressure applied to gas hydrate particles enhances gas hydrate preservation effects.

  15. Real-time monitoring of changes of adsorbed and crystalline water contents in tablet formulation powder containing theophylline anhydrate at various temperatures during agitated granulation by near-infrared spectroscopy.

    PubMed

    Otsuka, Makoto; Kanai, Yoshinori; Hattori, Yusuke

    2014-09-01

    Real-time monitoring of adsorbed water content (FW) and hydrate formation of theophylline anhydrate (THA) in tablet formulation during agitated granulation was investigated by near-infrared (NIR) spectroscopy. As the wet-granulation process of THA tablet formulation involves change in pseudo-polymorphs between THA and theophylline monohydrate (THM), the pharmaceutical properties of THA tablet depend on the degree of hydration during granulation. After mixing of the powder materials (4 g) containing THA, and excipients and the addition of 600 μL of binding water, the powder was kneaded at 27°C, 40°C, and 50°C and then dried. The mixing, granulating, and drying processes were monitored using NIR. The calibration models to predict THM and total water contents during granulation in THA tablet formulation were obtained by partial least-squares regression. The FW in the formulation was determined by subtracting THM from the water content. The results of the THA formulation powder bed during granulation by NIR monitoring indicated that the transformation pathway of the THA powder was THA ⇒ THM ⇒ THA at 27°C and 40°C, but that at 50°C was THA ⇒ THA ⇒ THA. The pharmaceutical properties, such as tablet porosity, hardness, tablet disintegration time, and dissolution rate of the final THA tablet products, were affected by the degree of crystalline transformation during granulation. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  16. Structures of hydrocarbon hydrates during formation with and without inhibitors.

    PubMed

    Ohno, Hiroshi; Moudrakovski, Igor; Gordienko, Raimond; Ripmeester, John; Walker, Virginia K

    2012-02-09

    The formation of hydrates from a methane-ethane-propane mixture is more complex than with single gases. Using nuclear magnetic resonance (NMR) and high-pressure powder X-ray diffraction (PXRD), we have investigated the structural properties of natural gas hydrates crystallized in the presence of kinetic hydrate inhibitors (KHIs), two commercial inhibitors and two biological ice inhibitors, or antifreeze proteins (AFPs). NMR analyses indicated that hydrate cage occupancy was at near saturation for controls and most inhibitor types. Some exceptions were found in systems containing a new commercial KHI (HIW85281) and a recombinant plant AFP, suggesting that these two inhibitors could impact the kinetics of cavity formation. NMR analysis confirmed that the hydrate composition varies during crystal growth by kinetic effects. Strikingly, the coexistence of both structures I (sI) and II (sII) were observed in NMR spectra and PXRD profiles. It is suggested that sI phases may form more readily from liquid water. Real time PXRD monitoring showed that sI hydrates were less stable than sII crystals, and there was a conversion to the stable phase over time. Both commercial KHIs and AFPs had an impact on hydrate metastability, but transient sI PXRD intensity profiles indicated significantly different modes of interaction with the various inhibitors and the natural gas hydrate system.

  17. Structural studies of a non-stoichiometric channel hydrate using high resolution X-ray powder diffraction, solid-state nuclear magnetic resonance, and moisture sorption methods.

    PubMed

    Kiang, Y-H; Cheung, Eugene; Stephens, Peter W; Nagapudi, Karthik

    2014-09-01

    Structural investigations of a nonstoichiometric hydrate, AMG 222 tosylate, a DPP-IV inhibitor in clinical development for type II diabetes, were performed using a multitechnique approach. The moisture sorption isotherm is in good agreement with a simple Langmuir model, suggesting that the hydrate water is located in well-defined crystallographic sites, which become vacant during dehydration. Crystal structures of AMG 222 tosylate at ambient and dry conditions were determined from high-resolution X-ray diffraction using the direct space method. On the basis of these crystal structures, hydrated water is located in channels formed by the drug framework. Upon dehydration, an isostructural dehydrate is formed with the channels remaining void and accessible to water for rehydration. Kitaigorodskii packing coefficients of the solid between relative humidity of 0% and 90% indicate that the equilibrium form of AMG 222 tosylate is the fully hydrated monohydrate.

  18. Hydrate detection

    SciTech Connect

    Dillon, W.P.; Ahlbrandt, T.S.

    1992-06-01

    Project objectives were: (1) to create methods of analyzing gas hydrates in natural sea-floor sediments, using available data, (2) to make estimates of the amount of gas hydrates in marine sediments, (3) to map the distribution of hydrates, (4) to relate concentrations of gas hydrates to natural processes and infer the factors that control hydrate concentration or that result in loss of hydrate from the sea floor. (VC)

  19. Hydrate detection

    SciTech Connect

    Dillon, W.P.; Ahlbrandt, T.S.

    1992-01-01

    Project objectives were: (1) to create methods of analyzing gas hydrates in natural sea-floor sediments, using available data, (2) to make estimates of the amount of gas hydrates in marine sediments, (3) to map the distribution of hydrates, (4) to relate concentrations of gas hydrates to natural processes and infer the factors that control hydrate concentration or that result in loss of hydrate from the sea floor. (VC)

  20. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    SciTech Connect

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  1. Setting time and formability of calcium phosphate cements prepared using modified dicalcium phosphate anhydrous powders.

    PubMed

    Sawamura, Takenori; Mizutani, Yoichiro; Okuyama, Masahiko; Kasuga, Toshihiro

    2014-07-01

    Calcium phosphate cements (CPCs) were prepared using Ca4(PO4)2O (TeCP) and modified CaHPO4 (DCPA) to evaluate the effects of the powder properties for DCPA particles on the setting time and formability of the resulting CPCs. Two types of modified DCPA were prepared by milling commercially available DCPA with ethanol (to produce E-DCPA) or distilled water (to produce W-DCPA). The E-DCPA samples consisted of well-dispersed, fine primary particles, while the W-DCPA samples contained agglomerated particles, and had a smaller specific surface area. The mean particle size decreased with increased milling time in both cases. The raw CPC powders prepared using W-DCPA had a higher packing density than those prepared using E-DCPA, regardless of the mean particle size. The setting time of the CPC paste after mixing with distilled water decreased with decreases in the mean particle size and specific surface area, for both types of DCPA. The CPCs prepared using W-DCPA showed larger plasticity values compared with those prepared using E-DCPA, which contributed to the superior formability of the W-DCPA samples. The CPCs prepared using W-DCPA showed a short setting time and large plasticity values, despite the fact that only a small amount of liquid was used for the mixing of the raw CPC powders (a liquid-to-powder ratio of 0.25 g g(-1) was used). It is likely that the higher packing density of the raw CPC powders prepared using W-DCPA was responsible for the higher performance of the resulting CPCs.

  2. Time-resolved studies of impact-initiated combustion in aluminum powder compacts

    NASA Astrophysics Data System (ADS)

    Breidenich, Jennifer; Dixon, Sean; Aydelotte, Brady; Thadhani, Naresh

    2011-06-01

    The mechanisms of combustion reaction occurring under impact loading of aluminum powder compacts are studied using UV/Vis spectroscopy to gain time-resolved chemical information. Impact experiments performed on aluminum powder compacts reveal light emission due to reaction at velocities greater than 400m/s in air, while no reaction is observed in a vacuum (50mTorr). Light emission and reaction occurrence is also sensitive to the density of the Al powder compacts. Upon combustion, wavelengths indicative of the well-known reaction Al +O2 --> AlO + O , a sharp doublet at 398 nm and multiple broad peaks between 420 and 500 nm, are observed. Microsecond time-resolved chemical information is gained through analysis of these wavelengths using a spectrometer coupled with an electron multiplier CCD camera. The impact initiated reaction is also monitored by high speed imaging of transient deformation profiles which are compared to those predicted using numerical simulations employing ANSYS-AUTODYN-3D computer code. The insight obtained from the combination of these analyses of impact-initiated combustion reaction in aluminum powder compacts will be presented. Funded by DTRA, Grant No. HDTRA1-10-1-0038

  3. Time-series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

    NASA Astrophysics Data System (ADS)

    Philip, Brendan T.; Denny, Alden R.; Solomon, Evan A.; Kelley, Deborah S.

    2016-03-01

    An estimated 500-2500 gigatons of methane carbon is sequestered in gas hydrate at continental margins and some of these deposits are associated with overlying methane seeps. To constrain the impact that seeps have on methane concentrations in overlying ocean waters and to characterize the bubble plumes that transport methane vertically into the ocean, water samples and time-series acoustic images were collected above Southern Hydrate Ridge (SHR), a well-studied hydrate-bearing seep site ˜90 km west of Newport, Oregon. These data were coregistered with robotic vehicle observations to determine the origin of the seeps, the plume rise heights above the seafloor, and the temporal variability in bubble emissions. Results show that the locations of seep activity and bubble release remained unchanged over the 3 year time-series investigation, however, the magnitude of gas release was highly variable on hourly time scales. Bubble plumes were detected to depths of 320-620 m below sea level (mbsl), in several cases exceeding the upper limit of hydrate stability by ˜190 m. For the first time, sustained gas release was imaged at the Pinnacle site and in-between the Pinnacle and the Summit area of venting, indicating that the subseafloor transport of fluid and gas is not restricted to the Summit at SHR, requiring a revision of fluid-flow models. Dissolved methane concentrations above background levels from 100 to 300 mbsl are consistent with long-term seep gas transport into the upper water column, which may lead to the build-up of seep-derived carbon in regional subsurface waters and to increases in associated biological activity.

  4. Real-time powder diffraction studies of energy materials under non-equilibrium conditions

    PubMed Central

    Peterson, Vanessa K.; Auckett, Josie E.; Pang, Wei-Kong

    2017-01-01

    Energy materials form the central part of energy devices. An essential part of their function is the ability to reversibly host charge or energy carriers, and analysis of their phase composition and structure in real time under non-equilibrium conditions is mandatory for a full understanding of their atomic-scale functional mechanism. Real-time powder diffraction is increasingly being applied for this purpose, forming a critical step in the strategic chemical engineering of materials with improved behaviour. This topical review gives examples of real-time analysis using powder diffraction of rechargeable battery electrodes and porous sorbent materials used for the separation and storage of energy-relevant gases to demonstrate advances in the insights which can be gained into their atomic-scale function.

  5. Advanced characterisation of encapsulated lipid powders regarding microstructure by time domain-nuclear magnetic resonance.

    PubMed

    Linke, Annika; Anzmann, Theresa; Weiss, Jochen; Kohlus, Reinhard

    2017-03-15

    Encapsulation is an established technique to protect sensitive materials from environmental stress. In order to understand the physical protection mechanism against oxidation, knowledge about the powder microstructure is required. Time domain-nuclear magnetic resonance (TD-NMR) has the potential to determine the surface oil (SO) and droplet size distribution by relaxation and restricted self-diffusion, respectively. The amount of SO, the retention and encapsulation efficiency are determined based on a lipid balance. The oil load of the initial powder and after SO removal is measured by TD-NMR. The results correlate with gravimetric and photometric references. The oil droplet size obtained by TD-NMR correlates well with static light scattering. The diameter of droplets in emulsions and dried powder both measured by TD-NMR, correlates (r = 0.998), implying that oil droplets embedded in a solid matrix can be measured. Summarising, TD-NMR allows analysis of the microstructure of encapsulated lipid powders, in a rapid, simple and non-destructive way.

  6. Time-Dependent Properties of Multimodal Polyoxymethylene Based Binder for Powder Injection Molding

    NASA Astrophysics Data System (ADS)

    Gonzalez-Gutierrez, Joamin; Stringari, Gustavo Beulke; Zupancic, Barbara; Kubyshkina, Galina; Bernstorff, Bernd Von; Emri, Igor

    Powder injection molding (PIM) is one of the most versatile methods for the manufacturing of small complex shaped components from metal, ceramic or cemented carbide powders for the use in many applications. PIM consists of mixing the powder and a polymeric binder, injecting this mixture in a mold, debinding and then sintering. Catalytic debinding of polyoxymethylene (POM) is attractive since it shows high debinding rates and low risk of cracking. This work examines the possibility of using POM with bimodal molecular mass distribution as the main component of the binding agent by studying its time-dependent properties and comparing them to monomodal POM. Furthermore, possible optimization of the binder formulation was investigated by the addition of shorter polymeric chains (wax) to bimodal POM, as to create a multimodal material. It was observed that the magnitude of the complex viscosity for the commercial bimodal material was more than 2 times lower than for the chemically identical monomodal POM within the investigated frequency range and temperature. Viscosity values were observed to drop as the content of wax was increased, without compromising the binders mechanical properties in solid state. A new formulation of bimodal POM plus 8 wt.% of added wax provided the most appropriate results from investigated combinations. This work has shown how the addition of short polymeric chains in POM influences its time-dependent properties in solid and molten state, which can be an important tool for the optimization of binders designed to be used in PIM technology.

  7. Characterization of non-stoichiometric hydration and the dehydration behavior of sitafloxacin hydrate.

    PubMed

    Suzuki, Tetsuya; Araki, Tetsuya; Kitaoka, Hiroaki; Terada, Katsuhide

    2012-01-01

    Sitafloxacin (STFX) hydrate is a non-stoichiometric hydrate. The hydration state of STFX hydrate varies non-stoichiometrically depending on the relative humidity and temperature, though X-ray powder diffraction (XRPD) of STFX hydrate was not affected by storing at low and high relative humidities. The detailed properties of crystalline water of STFX hydrate were estimated in terms of hygroscopicity, thermal analysis combined with X-ray powder diffractometry, crystallography and density functional theory (DFT) calculation. STFX hydrate changed the water contents continuously and reversibly from an equivalent amount of dihydrate through that of sesquihydrate depending on the relative humidity at 25°C. Thermal analysis and X-ray powder diffraction (XRPD) simultaneous measurement also revealed that STFX hydrate dehydrated into a hydrated state equivalent to monohydrate by heating up to 100°C, whereas XRPD patterns were slightly affected. This indicated that the crystal structure of STFX hydrate was retained at the dehydration level of monohydrate. Single-crystal X-ray structural analysis showed that two STFX molecules and four water molecule sites were contained in an asymmetric unit. STFX molecules formed a channel structure where water molecules were included. At the partially dehydrated state, at least two of four water molecules were considered to be disordered in occupancy and/or coordinates. Insight into the crystal structure of STFX hydrate stored at low and high relative humidities and geometry of the hydrogen bond were helpful to estimate the origin of non-stoichiometric hydration of STFX hydrate.

  8. Temporal Characterization of Hydrates System Dynamics beneath Seafloor Mounds. Integrating Time-Lapse Electrical Resistivity Methods and In Situ Observations of Multiple Oceanographic Parameters

    SciTech Connect

    Lutken, Carol; Macelloni, Leonardo; D'Emidio, Marco; Dunbar, John; Higley, Paul

    2015-01-31

    detect short-term changes within the hydrates system, identify relationships/impacts of local oceanographic parameters on the hydrates system, and improve our understanding of how seafloor instability is affected by hydrates-driven changes. A 2009 DCR survey of MC118 demonstrated that we could image resistivity anomalies to a depth of 75m below the seafloor in water depths of 1km. We reconfigured this system to operate autonomously on the seafloor in a pre-programmed mode, for periods of months. We designed and built a novel seafloor lander and deployment capability that would allow us to investigate the seafloor at potential deployment sites and deploy instruments only when conditions met our criteria. This lander held the DCR system, controlling computers, and battery power supply, as well as instruments to record oceanographic parameters. During the first of two cruises to the study site, we conducted resistivity surveying, selected a monitoring site, and deployed the instrumented lander and DCR, centered on what appeared to be the most active locations within the site, programmed to collect a DCR profile, weekly. After a 4.5-month residence on the seafloor, the team recovered all equipment. Unfortunately, several equipment failures occurred prior to recovery of the instrument packages. Prior to the failures, however, two resistivity profiles were collected together with oceanographic data. Results show, unequivocally, that significant changes can occur in both hydrate volume and distribution during time periods as brief as one week. Occurrences appear to be controlled by both deep and near-surface structure. Results have been integrated with seismic data from the area and show correspondence in space of hydrate and structures, including faults and gas chimneys.

  9. Feasibility of terahertz time-domain spectroscopy to detect tetracyclines hydrochloride in infant milk powder.

    PubMed

    Qin, Jianyuan; Xie, Lijuan; Ying, Yibin

    2014-12-02

    We report the use of terahertz time-domain spectroscopy (THz-TDS) to detect tetracyclines hydrochloride (TCsH) in infant milk powder for the first time. Four kinds of TCsH exhibited their unique spectral features in the region of 0.3-1.8 THz. The main spectral features of these TCsH were still detectable when mixed with infant milk powder with concentrations at 1%-50%, even in the ternary mixtures. The results from chemometrics analysis showed that qualitative and quantitative detection of TCsH in infant milk powder could be successfully achieved. The residual predictive deviation (RPD) values of all these TCsH models were all higher than 2, indicating these models were considered good and could be used in screening purposes. The RPD values of TCH, DTCH, and CTCH models were higher than 3, which were considered excellent for prediction purposes. These preliminary results indicated that THz-TDS combined with chemometrics analysis was suitable for detecting the presence of TCsH residues in a food matrix.

  10. Time-Dependent Electrical Properties of Human Nail Upon Hydration In Vivo

    PubMed Central

    HAO, JINSONG; SMITH, KELLY A.; LI, S. KEVIN

    2009-01-01

    The objectives of this study were to investigate the effects of hydration and solution ion concentration on the electrical properties of human nail in vivo and compare these in vivo results with those in vitro. In vivo electrical resistance measurements on the nail were conducted with a three-electrode system in phosphate buffered saline of 0.01–0.6 M. The effect of electric current on nail resistance and possible adverse effects were studied under 1.5- and 9-V iontophoresis in vivo. The electrical resistance of the nail plate was measured in vitro in side-by-side diffusion cells under the same conditions and compared with those in vivo. The in vivo electrical resistance decreased significantly upon 2-h nail hydration and then slowly decreased to a constant value, showing the same pattern as that in vitro. No significant effect of the applied voltage upon the nail electrical resistance was observed. Higher current densities caused moderate sensation and slight changes in nail appearance after iontophoresis. The observed decrease in nail resistance demonstrates the significance of nail hydration in transungual iontophoresis. The in vitro and in vivo correlation suggests that the in vitro nail plate can be a model in the research and development of transungual iontophoretic delivery. PMID:19462425

  11. Effects of laser sintering processing time and temperature on changes in polyamide 12 powder particle size, shape and distribution

    NASA Astrophysics Data System (ADS)

    Mielicki, C.; Gronhoff, B.; Wortberg, J.

    2014-05-01

    In laser sintering (LS) un-molten Polyamide 12 (PA12) powder is usually re-used (recycled) in further processes. However, LS processing time at powder bed temperature leads to material property changes. As a consequence, un-molten PA12 powder that is re-used or recycled in further processes leads to process and part properties deviations. In this context, powder particle size, shape and distribution is assumed to affect surface roughness and porosity of LS parts. In order to investigate this process effect on changes in powder size, shape and distribution, PA12 powder was systematically aged in a vacuum oven at conditions close to the LS process. According to this procedure, polymeric powder was obtained with aging times up to 120 hours and analyzed by dynamic image analysis. At first, fresh powder was investigated as a reference. The effect of LS processing time and temperature, i.e. powder bed temperature of approx. 174°C was measured with respect to changes in size distribution and shape whereas particles were considered of size up to 500μm. The influence of LS processing time at powder bed temperature was found to be neither significant on changes in particle size nor distribution. With respect to particle shape, a higher deviation to the reference was observed for particle size bigger than 100 μm and longer aging times. Consequently, influences on particle shape changes on surface roughness are assumed to be more likely than influences on part porosity due to LS processing conditions.

  12. Hydration of anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill

    SciTech Connect

    Sievert, T.; Wolter, A.; Singh, N.B

    2005-04-01

    The hydration of an anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill was studied as a function of time and temperature. The amount of gypsum formed at different intervals of time was determined by weight loss method and powder X-ray diffraction technique. Specific surface area at different time intervals was determined by LASER granulometric method. The results showed that the maximum rate of formation of gypsum was at a longer time than the time for the development of maximum specific surface area. In the presence of activators, the time for maximum rate of gypsum formation and maximum specific surface area shifted towards lower hydration time. Morphological changes during the course of hydration have been studied by the scanning electron microscopic (SEM) technique. A mechanism of hydration has been proposed.

  13. Real-Time Label-Free Detection of Suspicious Powders Using Noncontact Optical Methods

    DTIC Science & Technology

    2013-11-05

    baking powder, baking soda, aspirin , Aleve, and acetaminophen, as well as inorganic Army Phase I SBIR W911NF-13-C-005 Final Report Photon Systems...baked) Gypsum BaSO4 Kaolinite Talc Organic)Powders Baking(Powder Powdered(Sugar Baking(Soda Fruit(Pectin Flour Cornstarch Aspirin Microbe)Standards B...fruit pectin, flower, corn starch, baking powder, baking soda, aspirin , Aleve, and acetaminophen are shown in Fig. B2 below. The spurious laser

  14. Hydration of surfactant-modified and PEGylated cationic cholesterol-based liposomes and corresponding lipoplexes by monitoring a fluorescent probe and the dielectric relaxation time.

    PubMed

    Maitani, Yoshie; Nakamura, Ayako; Tanaka, Takumi; Aso, Yukio

    2012-05-10

    For the optimization of plasmid DNA (pDNA)-cationic lipid complexes and lipoplex delivery, proper indexes of the physicochemical properties of lipoplexes are required. In general, the characteristics of lipoplexes are defined by particle size and zeta-potential at various mixing ratios of cationic liposomes and pDNA. In this study, we characterized the hydration level of surfactant-modified and PEGylated cationic cholesterol-based (OH-Chol) liposomes and their lipoplexes by monitoring both the fluorescent probe laurdan and the dielectric relaxation time. Fluorescence measurement using laurdan detected hydration of the headgroup of lipids in surfactant-modified liposomes and PEGylated DOTAP-liposomes, but hardly any fluorescence was detected in PEGylated OH-Chol-liposomes because the PEG layers may extend and cover the fluorescent maker. On the other hand, the measurement of dielectric relaxation time of water molecules revealed total hydration, including hydration of the PEG layer and the headgroup of cationic lipids. Furthermore, we found an inverse correlation between hydration level and cellular uptake of PEGylated lipoplexes (R=0.946). This finding indicated that the dielectric relaxation time of water molecules provides an important indicator of hydration of liposome and lipoplexes along with the fluorescence intensity of laurdan. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry.

    PubMed

    Zhang, Liya; Yong, Wei; Liu, Jiahui; Wang, Sai; Chen, Qilong; Guo, Tianyang; Zhang, Jichuan; Tan, Tianwei; Su, Haijia; Dong, Yiyang

    2015-08-01

    The direct analysis in real time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) system has the capability to desorb analytes directly from samples without sample cleanup or chromatographic separation. In this work, a method based on DART/Q-TOF MS/MS has been developed for rapid identification of dicyandiamide (DCD) present in powdered milk. Simple sample extraction procedure employing acetonitrile-water (80:20, v/v) mixture was followed by direct, high-throughput determination of sample extracts spread on a steel mesh of the transmission module by mass spectrometry under ambient conditions. The method has been evaluated for both qualitative and quantitative analysis of DCD in powdered milk. Variables including experimental apparatus, DART gas heater temperature, sample presentation speed, and vacuum pressure were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision, and accuracy by using external standards. After optimization of these parameters, a limit of detection (LOD) of 100 μg kg(-1) was obtained for DCD with a linear working range from 100 to 10000 μg kg(-1) and a satisfactory correlation coefficient (R(2)) of 0.9997. Good recovery (80.08%-106.47%) and repeatability (RSD = 3.0%-5.4%) were achieved for DCD. The DART/Q-TOF MS/MS-based method provides a rapid, efficient, and powerful scheme to analyze DCD in powdered milk with limited sample preparation, thus reducing time and complexity of quality control.

  16. Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Liya; Yong, Wei; Liu, Jiahui; Wang, Sai; Chen, Qilong; Guo, Tianyang; Zhang, Jichuan; Tan, Tianwei; Su, Haijia; Dong, Yiyang

    2015-08-01

    The direct analysis in real time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) system has the capability to desorb analytes directly from samples without sample cleanup or chromatographic separation. In this work, a method based on DART/Q-TOF MS/MS has been developed for rapid identification of dicyandiamide (DCD) present in powdered milk. Simple sample extraction procedure employing acetonitrile-water (80:20, v/v) mixture was followed by direct, high-throughput determination of sample extracts spread on a steel mesh of the transmission module by mass spectrometry under ambient conditions. The method has been evaluated for both qualitative and quantitative analysis of DCD in powdered milk. Variables including experimental apparatus, DART gas heater temperature, sample presentation speed, and vacuum pressure were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision, and accuracy by using external standards. After optimization of these parameters, a limit of detection (LOD) of 100 μg kg-1 was obtained for DCD with a linear working range from 100 to 10000 μg kg-1 and a satisfactory correlation coefficient (R2) of 0.9997. Good recovery (80.08%-106.47%) and repeatability (RSD = 3.0%-5.4%) were achieved for DCD. The DART/Q-TOF MS/MS-based method provides a rapid, efficient, and powerful scheme to analyze DCD in powdered milk with limited sample preparation, thus reducing time and complexity of quality control.

  17. Development and evaluation of mathematical model to predict disintegration time of fast disintegrating tablets using powder characteristics.

    PubMed

    Goel, H; Arora, A; Tiwary, A K; Rana, V

    2011-02-01

    The objective of the study was to develop a mathematical model for predicting the disintegration time of fast disintegrating tablets (FDTs) by estimating the powder characteristics of powder blend prior to compression. A combination of chitosan-alginate complex and glycine in the ratio of 50:50 was used for preparing FDTs. The developed mathematical model allowed water sorption time (WST), effective pore radius (R(eff.p)) and swelling Index (SI) of powder mixture as well as tablet crushing strength to be successfully correlated with disintegration time (DT) of FDTs. The predicted model showed that disintegration time of FDTs to be directly correlated with powder characteristics and inversely correlated with tablet crushing strength. Furthermore, a correlation of 0.97 was obtained when DT of FDTs was compared with SI/(WST * R(eff.p)). This correlation was not affected by inclusion of water soluble (ondansetron hydrochloride or metaclopramide hydrochloride) or water insoluble (domperidone) drugs in the powder blend or FDTs. These observations indicated the versatility of the mathematical model in predicting the disintegration time of FDTs by evaluating the selected characteristics of the powder blends without actually preparing the FDTs.

  18. Hydration kinetics of cements by Time-Domain Nuclear Magnetic Resonance: Application to Portland-cement-derived endodontic pastes

    SciTech Connect

    Bortolotti, Villiam; Fantazzini, Paola; Sauro, Salvatore; Zanna, Silvano

    2012-03-15

    Time-Domain Nuclear Magnetic Resonance (TD-NMR) of {sup 1}H nuclei is used to monitor the maturation up to 30 days of three different endodontic cement pastes. The 'Solid-liquid' separation of the NMR signals and quasi-continuous distributions of relaxation times allow one to follow the formation of chemical compounds and the build-up of the nano- and subnano-structured C-S-H gel. {sup 1}H populations, distinguished by their different mobilities, can be identified and assigned to water confined within the pores of the C-S-H gel, to crystallization water and Portlandite, and to hydroxyl groups. Changes of the TD-NMR parameters during hydration are in agreement with the expected effects of the different additives, which, as it is known, can substantially modify the rate of reactions and the properties of cementitious pastes. Endodontic cements are suitable systems to check the ability of this non-destructive technique to give insight into the complex hydration process of real cement pastes.

  19. Neutron powder diffraction study of the layer organic-inorganic hybrid iron(II) methylphosphonate-hydrate, Fe[(CD 3PO 3)(D 2O)

    NASA Astrophysics Data System (ADS)

    Léone, Philippe; Bellitto, Carlo; Bauer, Elvira M.; Righini, Guido; André, Gilles; Bourée, Françoise

    2008-11-01

    The crystal and magnetic structures of the hybrid organic-inorganic layer compound Fe[(CD 3PO 3)(D 2O)] have been studied by neutron powder diffraction as a function of temperature down to 1.5 K. The neutron diffraction pattern recorded at 200 K shows that the fully deuterated compound crystallizes in one of the two known forms of the undeuterated Fe[(CH 3PO 3)(H 2O)]. The crystal structure is orthorhombic, space group Pmn2 1, with the following unit-cell parameters: a=5.7095(1) Å, b=8.8053(3) Å and c=4.7987(1) Å; Z=2. The crystal structure remains unchanged on cooling from 200 to 1.5 K. Moreover, at low temperature, Fe[(CD 3PO 3)(D 2O)] shows a commensurate magnetic structure ( k=(0,0,0)). As revealed by bulk susceptibility measurements on Fe[(CH 3PO 3)(H 2O)], the magnetic structure corresponds to a canted antiferromagnet with a critical temperature TN=25 K. Neutron powder diffraction reveals that below TN=23.5 K the iron magnetic moments in Fe[(CD 3PO 3)(D 2O)] are antiferromagnetically coupled and oriented along the b-axis, perpendicular to the inorganic layers. No ferromagnetic component is observable in the neutron powder diffraction experiment, due to its too small value (<0.1 μB).

  20. Probing protein hydration and aging of food materials by the magnetic field dependence of proton spin-lattice relaxation times.

    PubMed

    Godefroy, Sophie; Korb, Jean-Pierre; Creamer, Lawrence K; Watkinson, Philip J; Callaghan, Paul T

    2003-11-15

    Most cheeses can be considered as solid emulsions of milk fat in a matrix of water and proteins. Regions of each of the phases can be liquid during processing and maturation. Identifying these regions and monitoring changes in them is important as a prelude to controlling the structure of the final cheese. We concentrate on the behavior of water in the vicinity of proteins as a function of cheese aging. Our method utilizes nuclear magnetic relaxation dispersion (NMRD) associated with the frequency dependence of water spin-lattice relaxation rates using the field cycling NMR technique. This method provides insight into the dynamical behavior of water molecules on a very large time scale. Moreover, we can distinguish between molecular motion in bulk and motion in the vicinity of a source of relaxation, such as proteins. A fit of our dispersion data using a theory developed by J.-P. Korb and R.G. Bryant (J. Chem. Phys. 115 (2001) 23) allowed us to determine the degree of hydration of proteins as a function of aging. In particular, we find that protein hydration increases with ripening.

  1. Optimal methodologies for terahertz time-domain spectroscopic analysis of traditional pigments in powder form

    NASA Astrophysics Data System (ADS)

    Ha, Taewoo; Lee, Howon; Sim, Kyung Ik; Kim, Jonghyeon; Jo, Young Chan; Kim, Jae Hoon; Baek, Na Yeon; Kang, Dai-ill; Lee, Han Hyoung

    2017-05-01

    We have established optimal methods for terahertz time-domain spectroscopic analysis of highly absorbing pigments in powder form based on our investigation of representative traditional Chinese pigments, such as azurite [blue-based color pigment], Chinese vermilion [red-based color pigment], and arsenic yellow [yellow-based color pigment]. To accurately extract the optical constants in the terahertz region of 0.1 - 3 THz, we carried out transmission measurements in such a way that intense absorption peaks did not completely suppress the transmission level. This required preparation of pellet samples with optimized thicknesses and material densities. In some cases, mixing the pigments with polyethylene powder was required to minimize absorption due to certain peak features. The resulting distortion-free terahertz spectra of the investigated set of pigment species exhibited well-defined unique spectral fingerprints. Our study will be useful to future efforts to establish non-destructive analysis methods of traditional pigments, to construct their spectral databases, and to apply these tools to restoration of cultural heritage materials.

  2. In-situ time resolved synchrotron powder diffraction studies of synthesis and chemical reactions

    SciTech Connect

    Norby, P.

    1995-09-01

    Equipment for time and temperature dependent powder diffraction has been developed, especially in order to be able to study hydrothermal syntheses of zeolites. The system is very versatile and has so far been used to study e.g. hydrothermal syntheses of zeolites and aluminophosphates, syntheses of layered phosphates, formation of Sorel cements, dehydration and phase transformations of zeolites, solid state synthesis of lanthanum manganites, ion exchange of zeolites using molten salt, and oxidation/reduction of lanthanum manganites at high temperatures. The sample is contained in quartz capillaries and is heated using a stream of hot air. External pressure can be applied allowing hydrothermal syntheses at temperatures up to 200 C to be performed. Controlled atmosphere is obtained by flowing gas or a mixture of gases through the capillary.

  3. On the numerical corrections of time-of-flight neutron powder diffraction data.

    SciTech Connect

    Avdeev, M.; Jorgensen, J.; Short, S.; Von Dreele, R.

    2007-08-01

    Time-of-flight neutron powder diffraction data for NIST Standard Reference Materials have been used to study the adequacy of the peak profile model obtained from a convolution of back-to-back exponentials with a pseudo-Voigt function that is widely used in Rietveld refinement. It is shown that, while the empirical models for d-spacing (wavelength) dependence of Gaussian and Lorentzian components of the pseudo-Voigt function and rise exponent are satisfactory, the behavior of the decay exponent and peak positions demonstrate significant deviations, which can be corrected by numerical methods. The practical side of this process as implemented in GSAS and FULLPROF and the effect of the corrections on the Rietveld analysis results are discussed.

  4. Tetrahydrofuran hydrate decomposition characteristics in porous media

    NASA Astrophysics Data System (ADS)

    Song, Yongchen; Wang, Pengfei; Wang, Shenglong; Zhao, Jiafei; Yang, Mingjun

    2016-12-01

    Many tetrahydrofuran (THF) hydrate properties are similar to those of gas hydrates. In the present work THF hydrate dissociation in four types of porous media is studied. THF solution was cooled to 275.15 K with formation of the hydrate under ambient pressure, and then it dissociated under ambient conditions. THF hydrate dissociation experiments in each porous medium were conducted three times. Magnetic resonance imaging (MRI) was used to obtain images. Decomposition time, THF hydrate saturation and MRI mean intensity (MI) were measured and analyzed. The experimental results showed that the hydrate decomposition time in BZ-4 and BZ-3 was similar and longer than that in BZ-02. In each dissociation process, the hydrate decomposition time of the second and third cycles was shorter than that of the first cycle in BZ-4, BZ-3, and BZ-02. The relationship between THF hydrate saturation and time is almost linear.

  5. Experimental investigation of sediment control on the saturation level of gas hydrate in sediments

    NASA Astrophysics Data System (ADS)

    Lu, H.; Ukita, T.; Noguchi, S.; Moudrakovski, I.; Shimada, T.; Ripmeester, J.; Ratcliffe, C.

    2010-12-01

    Except for those occurring at the seafloor, most natural gas hydrates form in sediments and are subject to the influence of the sediment. Investigations on natural gas hydrate have found that the saturation level of gas hydrate in sediments is closely related to the sediment type: comparatively enriched in coarse sediments such as sands but poorly saturated in fine sediments such as clay. However, due to the limitation of the current geological and geophysical investigations and the rarity of the recovery of intact hydrate samples, the knowledge about sediment control on hydrate saturation in sediments is still limited, and the mechanism is not yet understood. This research investigated the possible factors involved in sediment control on hydrate saturation using an experimental approach. The experiments were carried out with both natural and artificial sediments. The natural sediments were recovered from gas hydrate reservoirs in the Nankai Trough, offshore Japan, Cascadia, offshore Vancouver Island, K-G basin, offshore India, and offshore Andaman Island. The artificial sediments were prepared with quartz powder, a representative of silicates and aluminosilicates, kaolinite and Na-montmorillonite, representatives of clay minerals, and calcite, representative of carbonate minerals. Methane hydrate was synthesized in the artificial sediments under conditions simulating the reservoir of natural gas hydrate, and its saturation levels were determined from the gas amount released from a known volume of sediment. The results indicate that particle size and mineral composition are the two main factors affecting hydrate saturation in sediments. In the range from 20 to 250 μm, the degree of conversion of water into hydrate increases dramatically with increase in particle size, from 3% to 82%, corresponding to a pore saturation from 4% to ~ 100%. Studies also found that the sorting effect of sediment particles can also play a certain role in affecting hydrate saturation

  6. Spectral phasor analysis of LAURDAN fluorescence in live A549 lung cells to study the hydration and time evolution of intracellular lamellar body-like structures.

    PubMed

    Malacrida, Leonel; Astrada, Soledad; Briva, Arturo; Bollati-Fogolín, Mariela; Gratton, Enrico; Bagatolli, Luis A

    2016-11-01

    Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (lamellar body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process governing the size and hydration of these intracellular LB-like structures. Specifically, a first step (days 1 to 7) is characterized by an increase in their size, followed by a second one (days 7 to 14) where the organelles display a decrease in their global hydration properties. Interestingly, our results also show that their hydration properties significantly differ from those observed in well-characterized artificial lamellar model membranes, challenging the notion that a pure lamellar membrane organization is present in these organelles at intracellular conditions. Finally, these LB-like structures show a significant increase in their hydration state upon secretion, suggesting a relevant role of entropy during this process. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps

    PubMed Central

    Jung, Alan P; Bishop, Phillip A; Al-Nawwas, Ali; Dale, R. Barry

    2005-01-01

    Context: Exercise-associated muscle cramps (EAMCs) are common among physically active individuals and are temporarily disabling; therefore, prevention is of great interest. Objective: To determine the role of hydration and electrolyte supplementation in the prevention of EAMCs. Design: Each subject completed 2 counterbalanced trials in a repeated-measures design. Setting: University of Alabama. Patients or Other Participants: College-aged men (n = 13) with a history of EAMCs. Intervention(s): In each trial, participants performed a calf-fatiguing protocol to induce EAMCs in the calf muscle group. Each trial was performed in a hot environment (dry bulb temperature of 37°C, relative humidity of 60%). In the carbohydrate-electrolyte trial, subjects consumed, at a rate similar to sweat loss, a carbohydrate-electrolyte beverage with sodium chloride added. In the hypohydration trial, subjects were not allowed to consume any fluids. Main Outcome Measure(s): We measured the incidence and time to onset of EAMCs. Results: Nine participants experienced cramps in the carbohydrate-electrolyte trial, compared with 7 in the hypohydration trial. Of the 7 individuals who had EAMCs in both trials, exercise duration before onset was more than doubled in the carbohydrate-electrolyte trial (36.8 ± 17.3 minutes) compared with the hypohydration trial (14.6 ± 5.0 minutes, P < .01). Conclusions: Consumption of a carbohydrate-electrolyte beverage before and during exercise in a hot environment may delay the onset of EAMCs, thereby allowing participants to exercise longer. However, it appears that dehydration and electrolyte loss are not the sole causes of EAMCs, because 69% of the subjects experienced EAMCs when they were hydrated and supplemented with electrolytes. PMID:15970952

  8. Dynamics in protein powders on the nanosecond-picosecond time scale are dominated by localized motions.

    PubMed

    Nickels, Jonathan D; García Sakai, Victoria; Sokolov, Alexei P

    2013-10-03

    We present analysis of nanosecond-picosecond dynamics of Green Fluorescence Protein (GFP) using neutron scattering data obtained on three spectrometers. GFP has a β-barrel structure that differs significantly from the structure of other globular proteins and is thought to result in a more rigid local environment. Despite this difference, our analysis reveals that the dynamics of GFP are similar to dynamics of other globular proteins such as lysozyme and myoglobin. We suggest that the same general concept of protein dynamics may be applicable to all these proteins. The dynamics of dry protein are dominated by methyl group rotations, while hydration facilitates localized diffusion-like motions in the protein. The latter has an extremely broad relaxation spectrum. The nanosecond-picosecond dynamics of both dry and hydrated GFP are localized to distances of ∼1-3.5 Å, in contrast to the longer range diffusion of hydration water.

  9. Hydration and Velocity Heterogeneity in the Mantle

    NASA Astrophysics Data System (ADS)

    Smyth, J. R.; Holl, C. M.; Jacobsen, S. D.; Manghnani, M. H.; Amulele, G.

    2003-12-01

    Olivine, wadsleyite, and ringwoodite are the mineral phases generally believed to compose the majority of the upper mantle and transition zone. Although nominally anhydrous, these phases can incorporate enough hydroxyl to significantly affect their P and S seismic velocities and to compose the planet's largest reservoir of water. Using single crystal X-ray diffraction, we have measured the effect of hydration on compression of Fo90 ringwoodite to 12 GPa. Using powder diffraction of synchrotron radiation we have measured compression to 50 GPa. Using GHz ultrasonic measurements on single crystals containing about one percent water by weight, we observe a reduction of P-wave velocity equivalent to an increase in temperature of 600° C and on S-wave velocity of 1000° C at ambient pressure. Single-crystal velocity measurements at pressure are in progress. The data obtained to date indicate that hydration of ringwoodite will have a larger effect on velocities in the Transition Zone (TZ) than does temperature within the uncertainties of each. We have measured the isothermal bulk moduli of hydrous wadsleyite by single-crystal X-ray diffraction and find a similar effect of hydration on the bulk modulus. Lateral velocity variations in the TZ are therefore more likely to reflect variations in hydration than variations in temperature, at least in regions distant from subduction zones. In tomographic images of the TZ in regions distant from active subduction, red is more likely to mean `wet' than it is to mean `hot'. Observed seismic velocities in the TZ are consistent with a pyrolite composition with 0.5 to 1.0 percent by weight H2O, but are not consistent with dry pyrolite compositions. This degree of hydration would allow for TZ storage of two to three times the amount of water currently in the hydrosphere.

  10. Active filtration of phosphorus on Ca-rich hydrated oil shale ash: does longer retention time improve the process?

    PubMed

    Liira, Martin; Kõiv, Margit; Mander, Ulo; Mõtlep, Riho; Vohla, Christina; Kirsimät, Kalle

    2009-05-15

    The purpose of this research was to investigate the phosphorus binding capacity of active filtration through hydrated Ca-rich oil shale ash sediment in a laboratory-scale experiment at different retention times. Three column experiments were established with hydraulic loading rates of 12 L d(-1), 18 L d(-1), and 24 L d(-1), with residence times of 12, 8, and 6 h, respectively. The results showed good removal efficiency (up to 91% at loading of 1.66 gP m(-2) d(-1)) in the experiment with the longest retention time. The overall performance of the filters did not, however, improve with increasing retention time, and the decrease in binding capacity was 41% at longer retention times. Chemical clogging by carbonate precipitates probably reduces the availability of Ca from the dissolution of unstable ash sediment mineral phases, and the phosphate removal decreases rapidly from 91% to 49% at loading of 1.66 gP m(-2) d(-1).

  11. Nanosecond Relaxation Dynamics of Hydrated Proteins: Water versus protein contributions

    SciTech Connect

    Khodadadi, S; Curtis, J. E.; Sokolov, Alexei P

    2011-01-01

    We have studied picosecond to nanosecond dynamics of hydrated protein powders using dielectric spectroscopy and molecular dynamics (MD) simulations. Our analysis of hydrogen-atom single particle dynamics from MD simulations focused on main ( main tens of picoseconds) and slow ( slow nanosecond) relaxation processes that were observed in dielectric spectra of similar hydrated protein samples. Traditionally, the interpretation of these processes observed in dielectric spectra has been ascribed to the relaxation behavior of hydration water tightly bounded to a protein and not to protein atoms. Detailed analysis of the MD simulations and comparison to dielectric data indicate that the observed relaxation process in the nanosecond time range of hydrated protein spectra is mainly due to protein atoms. The relaxation processes involve the entire structure of protein including atoms in the protein backbone, side chains, and turns. Both surface and buried protein atoms contribute to the slow processes; however, surface atoms demonstrate slightly faster relaxation dynamics. Analysis of the water molecule residence and dipolar relaxation correlation behavior indicates that the hydration water relaxes at much shorter time scales.

  12. Methane Hydrates: Chapter 8

    USGS Publications Warehouse

    Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

    2008-01-01

    produced through exploratory drilling programs; (2) the tools for gas hydrate detection and characterisation from remote sensing data; (3) the details of gas hydrate reservoir production behaviour through additional, well-monitored and longer duration field tests and (4) the understanding of the potential environmental impacts of gas hydrate resource development. The results of future production tests, in the context of varying market and energy supply conditions around the globe, will be the key to determine the ultimate timing and scale of the commercial production of natural gas from gas hydrates.

  13. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding

  14. Gas hydrates

    SciTech Connect

    Berecz, E.; Balla-Achs, M.

    1983-01-01

    In the presence of water, particularly at low temperatures, many industrial gas systems under pressure tend to form solid crystalline compounds. These compounds are referred to as gas hydrates, and result from the association of the gas molecules with water. This book draws attention to the theoretical, practical and technological aspects of this interesting and important class of compounds. The topics covered include the structures, properties and thermodynamic characteristics of the gas hydrates, the changes induced in the equilibrium conditions by additives, and the methods and studies relating to the prevention and elimination of hydrate plugs in technological operations with industrial gases. In the discussion of the technological aspects, special emphasis is given to the production and transportation of natural gas and to the application of freon coolants. Such questions as the possibility of the desalination of seawater and the formation of gas hydrates in interplanetary space are also dealt with.

  15. Optimization of milling time before and after recalcination on HTR processed strontium hexaferrite powder

    NASA Astrophysics Data System (ADS)

    Seyyed Ebrahimi, S. A.

    2006-12-01

    HTR (Hydrogen Treatment and Recalculation) process is a novel technique for heat treatment of conventional strontium hexaferrite powder in static hydrogen and then its recalcination in air. This process has a marked effect on the microstructure and on the magnetic properties of the material. In this work, this HTR-processed powder has been milled before and after recalcination, and the effect of milling on the magnetic properties has been optimized.

  16. Overview: Nucleation of clathrate hydrates

    NASA Astrophysics Data System (ADS)

    Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

    2016-12-01

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  17. Overview: Nucleation of clathrate hydrates.

    PubMed

    Warrier, Pramod; Khan, M Naveed; Srivastava, Vishal; Maupin, C Mark; Koh, Carolyn A

    2016-12-07

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  18. Rapid gas hydrate formation process

    DOEpatents

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  19. LOW TEMPERATURE X-RAY DIFFRACTION STUDIES OF NATURAL GAS HYDRATE SAMPLES FROM THE GULF OF MEXICO

    SciTech Connect

    Rawn, Claudia J; Sassen, Roger; Ulrich, Shannon M; Phelps, Tommy Joe; Chakoumakos, Bryan C; Payzant, E Andrew

    2008-01-01

    Clathrate hydrates of methane and other small alkanes occur widespread terrestrially in marine sediments of the continental margins and in permafrost sediments of the arctic. Quantitative study of natural clathrate hydrates is hampered by the difficulty in obtaining pristine samples, particularly from submarine environments. Bringing samples of clathrate hydrate from the seafloor at depths without compromising their integrity is not trivial. Most physical property measurements are based on studies of laboratory-synthesized samples. Here we report X-ray powder diffraction measurements of a natural gas hydrate sample from the Green Canyon, Gulf of Mexico. The first data were collected in 2002 and revealed ice and structure II gas hydrate. In the subsequent time the sample has been stored in liquid nitrogen. More recent X-ray powder diffraction data have been collected as functions of temperature and time. This new data indicates that the larger sample is heterogeneous in ice content and shows that the amount of sII hydrate decreases with increasing temperature and time as expected. However, the dissociation rate is higher at lower temperatures and earlier in the experiment.

  20. Time-resolved x-ray diffraction and Raman studies of the phase transition mechanisms of methane hydrate

    SciTech Connect

    Hirai, Hisako Kadobayashi, Hirokazu; Hirao, Naohisa; Ohishi, Yasuo; Ohtake, Michika; Yamamoto, Yoshitaka; Nakano, Satoshi

    2015-01-14

    The mechanisms by which methane hydrate transforms from an sI to sH structure and from an sH to filled-ice Ih structure were examined using time-resolved X-ray diffractometry (XRD) and Raman spectroscopy in conjunction with charge-coupled device camera observation under fixed pressure conditions. The XRD data obtained for the sI–sH transition at 0.8 GPa revealed an inverse correlation between sI and sH, suggesting that the sI structure is replaced by sH. Meanwhile, the Raman analysis demonstrated that although the 12-hedra of sI are retained, the 14-hedra are replaced sequentially by additional 12-hedra, modified 12-hedra, and 20-hedra cages of sH. With the sH to filled-ice Ih transition at 1.8 GPa, both the XRD and Raman data showed that this occurs through a sudden collapse of the sH structure and subsequent release of solid and fluid methane that is gradually incorporated into the filled-ice Ih to complete its structure. This therefore represents a typical reconstructive transition mechanism.

  1. Effects of storage time and temperature on lipid oxidation of egg powders enriched with natural antioxidants.

    PubMed

    Matumoto-Pintro, Paula Toshimi; Murakami, Alice Eiko; Vital, Ana Carolina Pelaes; Croge, Camila; da Silva, Denise Felix; Ospina-Roja, Ivan Camilo; Guerra, Ana Flávia Quiles Garcia

    2017-08-01

    The lipid fraction of egg powder may be affected by storage conditions due to the development of oxidative rancidity caused by polyunsaturated fatty acids. This study evaluated egg powders enriched with antioxidants [tocopherol, catechin, lycopene, and butylated hydroxyanisole (BHA)] for conjugated dienes (during a 90-day period) and for malonaldehydes (during a 210-day period) at 25±2 and 4±1°C. The presence of lycopene and BHA increases the total phenolic compounds in the enriched egg powders, and BHA exhibits the most antioxidant activity, as quantified by an ABTS assay. Egg powders enriched with antioxidants do not show any reduction in conjugate diene production compared to controls, and no effect of storage temperature is observed; however, in the production of malonaldehyde, greater stability is observed at 4°C, and catechin is more effective in reducing oxidation during storage. The results show that natural antioxidants can be used in egg powder instead of synthetic compounds to reduce malonaldehyde production during storage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. In situ radiolysis time-resolved ESR studies of spin trapping by DMPO: Re-evalution of hydroxyl radical and hydrated electron trapping rates and spin adduct yields

    SciTech Connect

    Madden, K.P.; Taniguchi, Hitoshi

    1996-05-02

    The second-order rate constants for the reaction of 5, 5-dimethyl-1-pyrroline N-oxide (DMPO) with radiolytically produced hydroxyl radicals and hydrated electrons have been measured in aqueous solution by direct observation of spin adduct initial yield using time-resolved electron spin resonance. The rate constants are 2.8 x 10{sup 9} mol{sup -1} dm{sup 3} S{sup -1} for the DMPO-hydroxyl radical reaction and 3.2 x 10{sup 9} mol{sup -1} dm{sup 3} s{sup -1} for the reaction of DMPO and hydrated electron, using sodium formate and chloroacetic acid as competitive scavengers of the hydroxyl radical and hydrated electron, respectively. The hydrated electron-DMPO competition study determined the fraction of DMPO-H produced directly from radiolytically produced hydrogen atoms as 0.082 of the total DMPO-H yield, indicating that approximately half of the hydrogen atoms react with DMPO to produce non-aminoxyl products. The fraction of the total hydroxyl radical yield leading to DMPO-OH spin adduct was determined to be 0.94, using the bleach of 2,2,6,6-tetramethylpiperidone-N-oxyl by carbon dioxide radical anion as a reference standard. 36 refs., 8 figs., 1 tab.

  3. Continuous time random walk with linear force applied to hydrated proteins

    NASA Astrophysics Data System (ADS)

    Fa, Kwok Sau

    2013-08-01

    An integro-differential diffusion equation with linear force, based on the continuous time random walk model, is considered. The equation generalizes the ordinary and fractional diffusion equations. Analytical expressions for transition probability density, mean square displacement, and intermediate scattering function are presented. The mean square displacement and intermediate scattering function can fit well the simulation data of the temperature-dependent translational dynamics of nitrogen atoms of elastin for a wide range of temperatures and various scattering vectors. Moreover, the numerical results are also compared with those of a fractional diffusion equation.

  4. Continuous time random walk with linear force applied to hydrated proteins.

    PubMed

    Fa, Kwok Sau

    2013-08-14

    An integro-differential diffusion equation with linear force, based on the continuous time random walk model, is considered. The equation generalizes the ordinary and fractional diffusion equations. Analytical expressions for transition probability density, mean square displacement, and intermediate scattering function are presented. The mean square displacement and intermediate scattering function can fit well the simulation data of the temperature-dependent translational dynamics of nitrogen atoms of elastin for a wide range of temperatures and various scattering vectors. Moreover, the numerical results are also compared with those of a fractional diffusion equation.

  5. Estimation of Time-Temperature-Transformation Diagrams of Mold Powder Slags from Thermo-analysis of Non-isothermal Crystallization

    NASA Astrophysics Data System (ADS)

    Maldonado, Yadira G.; Barraza de la P., Claudia; Rodríguez A., Sergio; Castillejos E., A. Humberto; Thomas, Brian G.

    2014-09-01

    The temperature range across the mold powder slag in the interfacial gap between the continuous casting mold and strand leads through different transformation behavior into crystalline phases. The transformation rates play a key role in determining the proportion of glassy and crystalline phases present, and thus greatly influence mold heat transfer and lubrication. Although thermal analysis has held great promise to quantify the crystallization of mold slags, so far the information it has provided is scarce. This work shows how differential scanning calorimetry, DSC, data allow evaluation of Time-Temperature-Transformation, TTT, diagrams of mold powder slags, when analyzed with the induction period and the Kissinger methods. The data required for estimating this important tool for the analysis and design of mold powders are onset temperature, T i, peak maximum temperature, T m, shape index, S, and conversion at peak maximum, x m, of the crystallization peaks appearing on thermograms obtained at various heating and cooling rates, ϕ or -ϕ, respectively. Industrial mold powders for casting low- and medium-carbon steels were analyzed to obtain TTT diagrams which correctly portray their different crystallization behavior. The diagrams reveal the start and end curves of the crystalline phases forming at each DSC crystallization peak. The estimated TTT curves present a correct picture of the degree of transformation observed in glass disks (~3 mm thick) treated isothermally for specified time intervals, quenched and examined with a scanning electron microscope. Additionally, the procedure developed for DSC-based TTT diagram calculation is supported by the good agreement between expected transformations and qualitative or quantitative X-ray diffraction results obtained from mold glass-powdered samples treated isothermally in a muffle furnace.

  6. Estimation of Time-Temperature-Transformation Diagrams of Mold Powder Slags from Thermo-analysis of Non-isothermal Crystallization

    NASA Astrophysics Data System (ADS)

    Maldonado, Yadira G.; Barraza de la P., Claudia; Rodríguez A., Sergio; Castillejos E., A. Humberto; Thomas, Brian G.

    2015-02-01

    The temperature range across the mold powder slag in the interfacial gap between the continuous casting mold and strand leads through different transformation behavior into crystalline phases. The transformation rates play a key role in determining the proportion of glassy and crystalline phases present, and thus greatly influence mold heat transfer and lubrication. Although thermal analysis has held great promise to quantify the crystallization of mold slags, so far the information it has provided is scarce. This work shows how differential scanning calorimetry, DSC, data allow evaluation of Time-Temperature-Transformation, TTT, diagrams of mold powder slags, when analyzed with the induction period and the Kissinger methods. The data required for estimating this important tool for the analysis and design of mold powders are onset temperature, T i, peak maximum temperature, T m, shape index, S, and conversion at peak maximum, x m, of the crystallization peaks appearing on thermograms obtained at various heating and cooling rates, ϕ or - ϕ, respectively. Industrial mold powders for casting low- and medium-carbon steels were analyzed to obtain TTT diagrams which correctly portray their different crystallization behavior. The diagrams reveal the start and end curves of the crystalline phases forming at each DSC crystallization peak. The estimated TTT curves present a correct picture of the degree of transformation observed in glass disks (~3 mm thick) treated isothermally for specified time intervals, quenched and examined with a scanning electron microscope. Additionally, the procedure developed for DSC-based TTT diagram calculation is supported by the good agreement between expected transformations and qualitative or quantitative X-ray diffraction results obtained from mold glass-powdered samples treated isothermally in a muffle furnace.

  7. Chloral hydrate

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 00 / 006 TOXICOLOGICAL REVIEW OF CHLORAL HYDRATE ( CAS No . 302 - 17 - 0 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) August 2000 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed in accordance w

  8. Computing the 7Li NMR chemical shielding of hydrated Li+ using cluster calculations and time-averaged configurations from ab initio molecular dynamics simulations.

    PubMed

    Alam, Todd M; Hart, David; Rempe, Susan L B

    2011-08-14

    Ab initio molecular dynamics (AIMD) simulations have been used to predict the time-averaged Li NMR chemical shielding for a Li(+) solution. These results are compared to NMR shielding calculations on smaller Li(+)(H(2)O)(n) clusters optimized in either the gas phase or with a polarizable continuum model (PCM) solvent. The trends introduced by the PCM solvent are described and compared to the time-averaged chemical shielding observed in the AIMD simulations where large explicit water clusters hydrating the Li(+) are employed. Different inner- and outer-coordination sphere contributions to the Li NMR shielding are evaluated and discussed. It is demonstrated an implicit PCM solvent is not sufficient to correctly model the Li shielding, and that explicit inner hydration sphere waters are required during the NMR calculations. It is also shown that for hydrated Li(+), the time averaged chemical shielding cannot be simply described by the population-weighted average of coordination environments containing different number of waters.

  9. Thermal decomposition of HfCl{sub 4} as a function of its hydration state

    SciTech Connect

    Barraud, E.; Begin-Colin, S. . E-mail: begin@ipcms.u-strasbg.fr; Le Caer, G.; Villieras, F.; Barres, O.

    2006-06-15

    The thermogravimetric behavior of HfCl{sub 4} powders with different hydration states has been compared. Strongly hydrated powders consist of HfOCl{sub 2}.nH{sub 2}O with n>4. Partially hydrated powders consist of particles with a HfCl{sub 4} core and a hydrated outerlayer of HfOCl{sub 2}.nH{sub 2}O with n in the range of 0-8. Hydrated powders decomposed at temperature lower than 200 deg. C whereas the decomposition of partially hydrated powders was completed at a temperature of around 450 deg. C. The observed differences in decomposition temperature is related to the structure of HfOCl{sub 2}.nH{sub 2}O, which is different if n is higher or smaller than 4 and leads to intermediate compounds, which decompose at different temperatures.

  10. Hydration water dynamics and instigation of protein structuralrelaxation

    SciTech Connect

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    Until a critical hydration level is reached, proteins do not function. This critical level of hydration is analogous to a similar lack of protein function observed for temperatures below a dynamical temperature range of 180-220K that also is connected to the dynamics of protein surface water. Restoration of some enzymatic activity is observed in partially hydrated protein powders, sometimes corresponding to less than a single hydration layer on the protein surface, which indicates that the dynamical and structural properties of the surface water is intimately connected to protein stability and function. Many elegant studies using both experiment and simulation have contributed important information about protein hydration structure and timescales. The molecular mechanism of the solvent motion that is required to instigate the protein structural relaxation above a critical hydration level or transition temperature has yet to be determined. In this work we use experimental quasi-elastic neutron scattering (QENS) and molecular dynamics simulation to investigate hydration water dynamics near a greatly simplified protein system. We consider the hydration water dynamics near the completely deuterated N-acetyl-leucine-methylamide (NALMA) solute, a hydrophobic amino acid side chain attached to a polar blocked polypeptide backbone, as a function of concentration between 0.5M-2.0M under ambient conditions. We note that roughly 50-60% of a folded protein's surface is equally distributed between hydrophobic and hydrophilic domains, domains whose lengths are on the order of a few water diameters, that justify our study of hydration dynamics of this simple model protein system. The QENS experiment was performed at the NIST Center for Neutron Research, using the disk chopper time of flight spectrometer (DCS). In order to separate the translational and rotational components in the spectra, two sets of experiments were carried out using different incident neutron wavelengths of 7

  11. Constraints of gas venting activity for the interstitial water geochemistry at the shallow gas hydrate site, eastern margin of the Japan Sea; results from high resolution time-series fluid sampling by OsmoSampler

    NASA Astrophysics Data System (ADS)

    Owari, S.; Tomaru, H.; Matsumoto, R.

    2016-12-01

    We have conducted ROV researches in the eastern margin of the Japan Sea where active gas venting and outcropping of gas hydrates were observed near the seafloor and have found the strength and location of venting had changed within a few days. These observations indicate the seafloor environments with the shallow gas hydrate system could have changed for short period compared to a geological time scale. We have applied a long-term osmotic fluid sampling system "OsmoSampler" on the active gas hydrate system for one year in order to document how the gas venting and gas hydrate activity have changed the geochemical environments near the seafloor. All the major ion concentrations in the interstitial water show synchronous increase and decrease repeatedly in three to five days, reflecting the incorporation and release of fresh water in gas hydrates in response to the gas concentration change near the sampling site. Dissolved methane concentration increases rapidly and excessively (over several mM) in the first 40 days corresponding to the active gas venting. The increases of methane concentration are often associated with high ion concentration during high water pressure period, indicating excess gas release from shallow gas pockets. Contrarily, enhanced gas hydrate growth may plug the fluid-gas paths in shallow sediment, reducing gas hydrate formation due to the decrease of methane flux. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

  12. Effect of Time and storage temperature on anthocyanin decay and antioxidant activity in wild blueberry ( Vaccinium angustifolium ) powder.

    PubMed

    Fracassetti, Daniela; Del Bo', Cristian; Simonetti, Paolo; Gardana, Claudio; Klimis-Zacas, Dorothy; Ciappellano, Salvatore

    2013-03-27

    This study evaluated the effects of storage on total and single anthocyanin (ACN) content, and total antioxidant activity (TAA) of freeze-dried wild blueberry (WB) powder maintained at 25, 42, 60, and 80 °C for 49 days. Storage reduced single and total ACN content at all of the temperatures; it was slower at 25 °C (-3% after 2 weeks), whereas it was faster at 60 °C (-60%) and at 80 °C (-85%) after 3 days. The values of half-life time (t1/2) were found to be 139, 39, and 12 days at 25, 42, and 60 °C, respectively, utilizing the Arrhenius equation. No significant effects were detected on TAA by temperature increase. In conclusion, this study provides important information on the stability of WB powder at 25 °C; this is interesting scientific research for the food industry.

  13. An Analysis of Shock-Compression in Mo-Si Powder Mixtures Using Recovery and Time-Resolved Measurements

    NASA Astrophysics Data System (ADS)

    Vandersall, Kevin S.; Thadhani, Naresh N.

    1999-06-01

    The densification and reaction characteristics in the Mo-Si system were investigated utilizing recovery experiments as well as time resolved measurements with in-situ stress gages. The starting sample in all cases consisted of statically pressed Mo + 2 Si powder mixtures ( ~55% TMD). The recovery experiments were performed using the Sandia Momma Bear and Momma Bear A fixtures with baratol and composition B explosives respectively. The instrumented experiments were performed in a capsule design similar to that of the Momma Bear, but modified to incorporate poly-vinyl di-flouride (PVDF) stress gages at the front and rear surfaces of the powder. These experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s. The instrumented experiments allow the crush strength, densification history, and reaction threshold to be mapped at increasing pressure to correlate with reaction observed in the recovery experiments.

  14. Olefin hydration

    SciTech Connect

    Butt, M.H.D.; Waller, F.J.

    1993-08-03

    An improved process for the hydration of olefins to alcohols is described wherein the improvement comprises contacting said olefins with the catalytic composition comprising a perfluorinated ion-exchange polymer containing sulfonic acid groups supported on an inert carrier wherein said carrier comprises calcined shot coke with a mean pore diameter of about 1,000 Angstroms in the presence of water at a temperature of from about 180 C to about 250 C.

  15. Ductile flow of methane hydrate

    USGS Publications Warehouse

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    2003-01-01

    Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

  16. Effects of preculturing conditions on lag time and specific growth rate of Enterobacter sakazakii in reconstituted powdered infant formula.

    PubMed

    Kandhai, M C; Reij, M W; Grognou, C; van Schothorst, M; Gorris, L G M; Zwietering, M H

    2006-04-01

    Enterobacter sakazakii can be present, although in low levels, in dry powdered infant formulae, and it has been linked to cases of meningitis in neonates, especially those born prematurely. In order to prevent illness, product contamination at manufacture and during preparation, as well as growth after reconstitution, must be minimized by appropriate control measures. In this publication, several determinants of the growth of E. sakazakii in reconstituted infant formula are reported. The following key growth parameters were determined: lag time, specific growth rate, and maximum population density. Cells were harvested at different phases of growth and spiked into powdered infant formula. After reconstitution in sterile water, E. sakazakii was able to grow at temperatures between 8 and 47 degrees C. The estimated optimal growth temperature was 39.4 degrees C, whereas the optimal specific growth rate was 2.31 h(-1). The effect of temperature on the specific growth rate was described with two secondary growth models. The resulting minimum and maximum temperatures estimated with the secondary Rosso equation were 3.6 degrees C and 47.6 degrees C, respectively. The estimated lag time varied from 83.3 +/- 18.7 h at 10 degrees C to 1.73 +/- 0.43 h at 37 degrees C and could be described with the hyperbolic model and reciprocal square root relation. Cells harvested at different phases of growth did not exhibit significant differences in either specific growth rate or lag time. Strains did not have different lag times, and lag times were short given that the cells had spent several (3 to 10) days in dry powdered infant formula. The growth rates and lag times at various temperatures obtained in this study may help in calculations of the period for which reconstituted infant formula can be stored at a specific temperature without detrimental impact on health.

  17. Dry stress and survival time of Enterobacter sakazakii and other Enterobacteriaceae in dehydrated powdered infant formula.

    PubMed

    Barron, Juncal Caubilla; Forsythe, Stephen J

    2007-09-01

    Powdered infant formula is not a sterile product, and opportunistic pathogens could multiply in the reconstituted product, resulting in neonatal infections. In this study, the generation of sublethally injured Enterobacteriaceae during desiccation and their persistence in dehydrated powdered infant formula was assessed during a 2.5-year period. The study included 27 strains of Enterobacter sakazakii, Enterobacter cloacae, Salmonella Enteritidis, Citrobacter koseri, Citrobacter freundii, Escherichia coli, Escherichia vulneris, Pantoea spp., Klebsiella oxytoca, and Klebsiella pneumoniae. The number of sublethally injured cells generated during desiccation was lower for K. oxytoca, Pantoea spp., Salmonella Enteritidis, and capsulated strains of E. sakazakii than for the other Enterobacteriaceae. The Enterobacteriaceae could be divided into three groups with respect to their long-term survival in the desiccated state. C. freundii, C. koseri, and E. cloacae were no longer recoverable after 6 months, and Salmonella Enteritidis, K. pneumoniae, and E. coli could not be recovered after 15 months. Pantoea spp., K. oxytoca, and E. vulneris persisted over 2 years, and some capsulated strains of E. sakazakii were still recoverable after 2.5 years.

  18. Gas hydrate hunting in China seas

    NASA Astrophysics Data System (ADS)

    Yang, J.; Zhang, X.; Chen, J.; Xiang, Q.; Ye, Y.; Gong, J.

    2003-04-01

    Gas hydrate research is a hotspot now in geosciences. Many countries have carried on gas hydrate survey and research for many years. China, as a country with large sea areas unfolded gas hydrate research work in its marine areas in 1999 and tries to keep pace with the advanced countries on gas hydrate study. Substantial funds were launched by various governmental and non-governmental funding agencies to support gas hydrate research. Many institutions on marine geosciences are involved in. China Geological Survey (CGS) has launched several research projects in the sea. So far, some fieldwork such as seismic survey, sampling, profiling, underwater video imaging have been done in South China Sea and East China Sea areas. Some preliminary results have been achieved. BSRs are found in many seismic profiles. Some potential gas hydrate bearing areas are marked and potential amount of gas hydrate resources is calculated. At the same time, gas hydrate laboratory was founded and successful experiments have been carried out to model the gas hydrate synthesis in accordance with the geological condition of the China seas. Now, gas hydrate detecting techniques such as sampling equipment (PCS), seismic data processing, interpretation and the formation mechanism study as well as environmental effect research are undergoing. Though China's gas hydrate research work is still at its initial stage, China is willing to be an active member in the international society of gas hydrate study and hopes to contribute its effort.

  19. Hydrate habitat

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    Whoever said there is nothing new under the sun did not delve deeply enough to the bottom of the ocean. There in the Gulf of Mexico, about 150 miles south of New Orleans, scientists have just discovered what could be a new species of centipede—like worms living on or within gas hydrates— mounds of methane ice— rising from the ocean floor.Scientists have previously recognized an association between some bacteria and these hydrates. However, this is the first discovery of a higher life form there.

  20. Thermal properties of methane gas hydrates

    USGS Publications Warehouse

    Waite, William F.

    2007-01-01

    Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to

  1. Effect of coating time on corrosion behavior of electroless nickel-phosphorus coated powder metallurgy iron specimens

    SciTech Connect

    Singh, D.; Balasubramaniam, R.; Dube, R.K.

    1995-08-01

    Powder metallurgy iron specimens with porosities in the range 0% to 2% were electroless coated with nickel-phosphorus alloy from baths containing sodium hypophosphite (NaH{sub 2}PO{sub 2}{center_dot}H{sub 2}O). The effect of coating time on thickness and phosphorus content of the deposit was analyzed. The free corrosion potentials and corrosion rates of the coated specimens were obtained by the Tafel extrapolation method in 1.0 M hydrochloric acid (HCl) solution. Corrosion rates of the coated specimens after heat treatment also were studied. The observed corrosion characteristics were explained by the mixed-potential theory.

  2. Time-resolved in situ powder X-ray diffraction reveals the mechanisms of molten salt synthesis.

    PubMed

    Moorhouse, Saul J; Wu, Yue; Buckley, Hannah C; O'Hare, Dermot

    2016-11-24

    We report the first use of high-energy monochromatic in situ X-ray powder diffraction to gain unprecedented insights into the chemical processes occurring during high temperature, lab-scale metal oxide syntheses. During the flux synthesis of the n = 4 Aurivillius phase, Bi5Ti3Fe0.5Cr0.5O15 at 950 °C in molten Na2SO4 we observe the progression of numerous metastable phases. Using sequential multiphase Rietveld refinement of the time-dependent in situ XRD data, we are able to obtain mechanistic understanding of this reaction under a range of conditions.

  3. Antiatherosclerotic and Cardioprotective Effects of Time-Released Garlic Powder Pills.

    PubMed

    Karagodin, Vasily P; Sobenin, Igor A; Orekhov, Alexander N

    2016-01-01

    Garlic is believed to produce beneficial changes in different cardiovascular risk factors, thus possessing antiatherosclerotic properties. The hypotensive and cholesterol-lowering effects were investigated in two studies in men with mild arterial hypertension and in men with mild hypercholesterolemia. Eight-week treatment resulted in the reduction of both systolic and diastolic blood pressure by 5.2% (P=0.008) and 4.0% (P=0.014), respectively. In hypolipidemic study, the 12-week treatment resulted in a decrease in LDL cholesterol by 11.8% (P=0.002), while HDL cholesterol increased by 11.5% (P=0.013). In men with cerebral atherosclerosis it has been demonstrated that 14-days treatment inhibited ADP-induced platelet aggregation by 25.4% (P<0.05) and increased plasma fibrinolytic activity by 22.4% (P<0.05). One more study was performed in high-risk patients to evaluate the changes of prognostic cardiovascular risk that was calculated using algorithms derived from Framingham and Muenster Studies. Twelve-months treatment lowered 10-years prognostic risk of CHD by 13.2% in men (P=0.005), and by 7.1% in women (P=0.040). Ten-year prognostic risk of acute myocardial infarction and sudden coronary death was lowered by 26.1% in men (P=0.025). The Atherosclerosis Monitoring and Atherogenicity Reduction Study (AMAR) was designed to estimate the effect of two-year treatment with garlic powder pills on the progression of carotid atherosclerosis in asymptomatic men. A significant correlation has been revealed between the changes in blood serum atherogenicity and the changes in carotid intima-media thickness (r=0.144, P=0.045). Evidence obtained from these studies as well as series of double-blinded placebo-controlled clinical trials indicates that garlic powder pills are effective for prevention of cardiovascular disorders.

  4. Preservation phenomena of methane hydrate in pore spaces.

    PubMed

    Hachikubo, Akihiro; Takeya, Satoshi; Chuvilin, Evgeny; Istomin, Vladimir

    2011-10-21

    Dissociation processes of methane hydrate synthesized with glass beads were investigated using powder X-ray diffraction and calorimetry. Methane hydrate formed with coarse glass beads dissociated quickly at 150-200 K; in this temperature range methane hydrate dissociates at atmospheric pressure. In contrast, methane hydrate formed with glass beads less than a few microns in size showed very high stability up to just below the melting point of ice, even though this temperature is well outside the zone of thermodynamic stability of the hydrate. The rate-determining steps for methane hydrate dissociation within pores are also discussed. The experimental results suggest that methane hydrate existing naturally within the pores of fine particles such as mud at low temperatures would be significantly more stable than expected thermodynamically. This journal is © the Owner Societies 2011

  5. Diffusion of CO2 During Hydrate Formation and Dissolution

    SciTech Connect

    Franklin M. Orr, Jr.

    2002-08-20

    Experiments were performed to measure the rate of diffusion of CO2 through hydrate films. Hydrate films were created in a capillary tube, and the growth of the hydrate film was measured. Difficulties were encountered in creating hydrate repeatedly, and some non-uniform growth of the films was observed. Sufficient observations were obtained to demonstrate that hydrate growth occurs preferentially on the hydrate/water side of the interface, rather than at the hydrate/CO2 interface. Diffusion coefficients were estimated from observations of the rate of growth of the hydrate film along with estimates of the solubility of CO2 in water and of the concentration gradient across the hydrate layer. The experimental observations indicate that hydrate formation occurs much more rapidly at the hydrate water interface than at the hydrate/CO2 interface. Any growth of hydrate at the CO2/hydrate interface was too slow to be observed at the time scale of the experiments. That observation is consistent with the idea that CO2 can move more easily through the hydrate, presumably by hopping between hydrate cages, than water can move through the hydrate, presumably by lattice hopping. Estimated diffusion coefficients were in the range 1-3E-06 cm2/sec. Those values are about an order of magnitude lower than the diffusion coefficient for CO2 in liquid water, but four orders of magnitude larger than the value for diffusion of CO2 in a solid. The rate of diffusion through the hydrate controls both the creation of new hydrate at the hydrate/water interface and the rate at which CO2 dissolves in the liquid water and diffuses away from the hydrate layer. Formation of a hydrate layer reduces the rate at which CO2 dissolves in liquid water.

  6. Properties and hydration products of lightweight and expansive cements. Part II: Hydration products

    SciTech Connect

    Lilkov, V.; Djabarov, N.; Bechev, G.; Petrov, O.

    1999-10-01

    The type and quantity of hydration products in cement stone (plain cement, lightweight cement with cenospheres, and cement mixed with expansive additive) hydrated at 20 and 75 C were studied. The changes in the cement stone structure under the influence of lightweight and expansive additives and raised hardening temperature were studied with complex thermal analysis, infrared spectroscopy, powder X-ray diffraction analysis, and scanning electron microscopy. In the case of raised hardening temperature, the cenospheres and the expansive additive improve the crystallization of hydration products. A chemical reaction between the cenospheres and portlandite formed from the cement hydration was observed, accompanied by a decrease of the portlandite quantity. The expansive additive stimulates the formation of hydration products, which were thermally stable and decompose at temperatures above 600 C.

  7. Catastrophic growth of gas hydrates in the presence of kinetic hydrate inhibitors.

    PubMed

    Cha, Minjun; Shin, Kyuchul; Seo, Yutaek; Shin, Ju-Young; Kang, Seong-Pil

    2013-12-27

    The effect of the concentration of kinetic hydrate inhibitors, polyvinylpyrrolidone (PVP), and polyvinylcaprolactam (PVCap) on the onset and growth of synthetic natural gas hydrates is investigated by measuring the hydrate onset time and gas consumption rate. Although the hydrate onset time is extended by increasing the concentration from 0.5 to 3.0 wt % for both PVP and PVCap, the growth rate of hydrates shows that the different tendency depends on the type of kinetic hydrate inhibitor and its concentration. For PVCap solution, the hydrate growth was slow for more than 1000 min after the onset at the concentration of 0.5 and 1.5 wt %. However, the growth rate becames almost 8 times faster at the concentration of 3.0 wt %, representing the catastrophic growth of hydrate just after the hydrate onset. (13)C NMR spectra of hydrates formed at 3.0 wt % of PVP and PVCap indicate the existence of both structures I and II. Cage occupancy of methane in large cages of structure II decreases significantly when compared to that for pure water. These results suggest that increasing the concentration of KHI up to 3.0 wt % may induce the earlier appearance of catastrophic hydrate growth and the existence of metastable structure I; thus, there needs to be an upper limit for using KHI to manage the formation of gas hydrates.

  8. Effect of Holding Time on Surface Films Formed on Molten AZ91D Alloy Protected by Graphite Powder

    NASA Astrophysics Data System (ADS)

    Li, Weihong; Zhou, Jixue; Ma, Baichang; Wang, Jinwei; Wu, Jianhua; Yang, Yuansheng

    2017-10-01

    Graphite powder was adopted to prevent the AZ91D magnesium alloy from oxidizing during the melting and casting process. The microstructure of the resultant surface films formed at 973 K (700 °C) holding for 0, 15, 30, 45, and 60 minutes was investigated by scanning electron microscopy, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) after mechanical polishing and chemical etching. The results indicated that the surface films were composed of a protective layer and the underneath particles with different morphology. The protective layer was continuous with a thickness of 200 to 1000 nm mainly consisting of MgO, MgF2, and C, while the underneath particles mainly consisted of MgF2 and MgAl2O4. The surface films were the result of the interaction between the graphite powder, the melt, and the ambient atmosphere. The number and the size of the underneath particles, determining the thickness uniformity of the surface films, and the unevenness of the microsurface morphology increased with holding time. The mechanism of holding time on the resultant surface films was also discussed.

  9. The residence time of organic matter in gas hydrate systems: Constraints from iodine and its isotopes at the Blake Ridge and Peru Trench

    NASA Astrophysics Data System (ADS)

    Snyder, G. T.; Dickens, G. R.; Fehn, U.

    2003-04-01

    Large gas hydrate deposits in marine sediment are dynamic systems where substantial amounts of carbon cycle between various solid, gas and dissolved phases over time. Recent modeling exercises, typically grounded with information from boreholes on the Blake Ridge (eastern United States margin), indicate this carbon cycling probably occurs over millions of years, so that while gas hydrate specimens may be very young, the overall deposit is older than surrounding sediment. Here we present measurements of iodine and 129I (half-life = 15.7 Myr) from gas hydrate bearing intervals on the Blake Ridge and Peru Trench, and discuss their significance in terms of carbon cycling. Pore waters on the Blake Ridge contain upwards of 1.7 mM of iodine with 129I/I ratios averaging 166x10-15. By contrast, pore waters from the Peru trench contain upwards of 1.2 mM of iodine with 129I/I ratios averaging 255x10-15. Depth profiles of dissolved iodide concentrations at both locations suggest a cycle whereby iodine is released from organic matter at deep depth, diffused upward, adsorbed onto organic matter at shallow depth, and subsequently buried. Iodine isotopic ratios decrease with depth, and inversely correlate with dissolved iodide, bromide, and dissolved organic carbon concentrations. A straightforward model applied to both sites indicates that iodine-rich organic carbon has accumulated for about 63 Myr on the Blake Ridge and about 42 myr in the Peru Trench. Thus, iodine and carbon cycling in both deposits is indeed very old, with the Blake Ridge possibly representing an extreme case. The longevity of Blake Ridge carbon cycling may explain why this system appears to contain more gas than the Peru Trench despite a lower input of organic carbon.

  10. Real-time monitoring of laser powder bed fusion process using high-speed X-ray imaging and diffraction

    DOE PAGES

    Zhao, Cang; Fezzaa, Kamel; Cunningham, Ross W.; ...

    2017-06-15

    Here, we employ the high-speed synchrotron hard X-ray imaging and diffraction techniques to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time. We demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions. In particular, the keyhole pore formation is experimentally revealed with high spatial and temporal resolutions. The solidification rate is quantitatively measured, and the slowly decrease in solidification rate during the relatively steady state could be a manifestation of the recalescencemore » phenomenon. The high-speed diffraction enables a reasonable estimation of the cooling rate and phase transformation rate, and the diffusionless transformation from β to α’ phase is evident. The data present here will facilitate the understanding of dynamics and kinetics in metal LPBF process, and the experiment platform established will undoubtedly become a new paradigm for future research and development of metal additive manufacturing.« less

  11. Obsidian Hydration: A New Paleothermometer

    SciTech Connect

    Anovitz, Lawrence {Larry} M; Riciputi, Lee R; Cole, David R; Fayek, Mostafa; Elam, J. Michael

    2006-01-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  12. Obsidian hydration: A new paleothermometer

    NASA Astrophysics Data System (ADS)

    Anovitz, Lawrence M.; Riciputi, Lee R.; Cole, David R.; Fayek, Mostafa; Elam, J. Michael

    2006-07-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  13. The role of heat transfer time scale in the evolution of the subsea permafrost and associated methane hydrates stability zone during glacial cycles

    NASA Astrophysics Data System (ADS)

    Malakhova, Valentina V.; Eliseev, Alexey V.

    2017-10-01

    Climate warming may lead to degradation of the subsea permafrost developed during Pleistocene glaciations and release methane from the hydrates, which are stored in this permafrost. It is important to quantify time scales at which this release is plausible. While, in principle, such time scale might be inferred from paleoarchives, this is hampered by considerable uncertainty associated with paleodata. In the present paper, to reduce such uncertainty, one-dimensional simulations with a model for thermal state of subsea sediments forced by the data obtained from the ice core reconstructions are performed. It is shown that heat propagates in the sediments with a time scale of ∼ 10-20 kyr. This time scale is longer than the present interglacial and is determined by the time needed for heat penetration in the unfrozen part of thick sediments. We highlight also that timings of shelf exposure during oceanic regressions and flooding during transgressions are important for simulating thermal state of the sediments and methane hydrates stability zone (HSZ). These timings should be resolved with respect to the contemporary shelf depth (SD). During glacial cycles, the temperature at the top of the sediments is a major driver for moving the HSZ vertical boundaries irrespective of SD. In turn, pressure due to oceanic water is additionally important for SD ≥ 50 m. Thus, oceanic transgressions and regressions do not instantly determine onsets of HSZ and/or its disappearance. Finally, impact of initial conditions in the subsea sediments is lost after ∼ 100 kyr. Our results are moderately sensitive to intensity of geothermal heat flux.

  14. Clathrate hydrates in nature.

    PubMed

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves.

  15. Solid state interconversion between anhydrous norfloxacin and its hydrates.

    PubMed

    Chongcharoen, Wanchai; Byrn, Stephen R; Sutanthavibul, Narueporn

    2008-01-01

    This work is focused on characterizing and evaluating the solid state interconversion of norfloxacin (NF) hydrates. Four stoichiometric NF hydrates, dihydrate, hemipentahydrate, trihydrate, pentahydrate and a disordered NF state, were generated by various methods and characterized by X-ray powder diffractometry (XRPD), thermal analysis and Karl Fisher titrimetry. XRPD patterns of all NF hydrates exhibited crystalline structures. NF hydrate conversion was studied with respect to mild elevated temperature and various degrees of moisture levels. NF hydrates transformed to anhydrous NF Form A after gentle heating at 60 degrees C for 48 h except dihydrate and trihydrate where mixture in XRPD patterns between anhydrous NF Form A and former structures existed. Desiccation of NF hydrates at 0% RH for 7 days resulted in only partial removal of water molecules from the hydrated structures. The hydrated transitional phase and the disordered NF state were obtained from the incomplete dehydration of NF hydrates after thermal treatment and pentahydrate NF after desiccation, respectively. Anhydrous NF Form A and NF hydrates transformed to pentahydrate NF when exposed to high moisture environment except dihydrate. In conclusion, surrounding moisture levels, temperatures and the duration of exposure strongly influenced the interconversion pathways and stoichiometry of anhydrous NF and its hydrates. (c) 2007 Wiley-Liss, Inc.

  16. Gas hydrate resources of northern Alaska

    USGS Publications Warehouse

    Collett, T.S.

    1997-01-01

    Large amounts of natural gas, composed mainly of methane, can occur in arctic sedimentary basins in the form of gas hydrates under appropriate temperature and pressure conditions. Gas hydrates are solids, composed of rigid cages of water molecules that trap molecules of gas. These substances are regarded as a potential unconventional source of natural gas because of their enormous gas-storage capacity. Most published gas hydrate resource estimates are highly simplified and based on limited geological data. The gas hydrate resource assessment for northern Alaska presented in this paper is based on a "play analysis" scheme, in which geological factors controlling the accumulation and preservation of gas hydrates are individually evaluated and risked for each hydrate play. This resource assessment identified two gas hydrate plays; the in-place gas resources within the gas hydrates of northern Alaska are estimated to range from 6.7 to 66.8 trillion cubic metres of gas (236 to 2,357 trillion cubic feet of gas), at the 0.50 and 0.05 probability levels respectively. The mean in-place hydrate resource estimate for northern Alaska is calculated to be 16.7 trillion cubic metres of gas (590 trillion cubic feet of gas). If this assessment is valid, the amount of natural gas stored as gas hydrates in northern Alaska could be almost seven times larger then the estimated total remaining recoverable conventional natural gas resources in the entire United States.

  17. Origin and evolution of fracture-hosted methane hydrate deposits

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Dugan, Brandon

    2010-11-01

    Fracture-hosted methane hydrate deposits exist at many sites worldwide. These sites often have hydrate present as vein and fracture fill, as well as disseminated through the pore space. We estimate that thousands to millions of years are required to form fracture systems by hydraulic fracturing driven by occlusion of the pore system by hydrate. This time scale is a function of rates of fluid flow and permeability loss. Low-permeability layers in a sedimentary column can reduce this time if the permeability contrast with respect to the surrounding sediments is of order 10 or greater. Additionally, we find that tensile fracturing produced by hydrate heave around hydrate lenses is a viable fracture mechanism over all but the lowermost part of the hydrate stability zone. With our coupled fluid flow-hydrate formation model we assess fracture formation at four well-studied hydrate provinces: Blake Ridge offshore South Carolina, Hydrate Ridge offshore Oregon, Keathley Canyon Block 151 offshore Louisiana, and the Krishna-Godavari Basin offshore India. We conclude that hydraulic fracturing due to pore pressure buildup is reasonable only at Hydrate Ridge and the Krishna-Godavari Basin owing to sediment age constraints, and that hydrate-filled fractures observed at Blake Ridge and Keathley Canyon Block 151 are formed either by hydrate heave or in preexisting fractures. Our findings offer new insight into the processes and time scales associated with fracture-hosted hydrate deposits, which help further our understanding of hydrate systems.

  18. New gas-hydrate phase: Synthesis and stability of clay methane hydrate intercalate

    NASA Astrophysics Data System (ADS)

    Guggenheim, Stephen; Koster van Groos, August F.

    2003-07-01

    Intercalated Na-rich montmorillonite methane hydrate was synthesized for the first time. The upper limit of stability for the intercalate in pressure and temperature is parallel to that of methane hydrate but at temperatures that are ˜0.5 1 °C lower than for methane hydrate. The low-temperature stability of the intercalate is at -11.5 ± 3 °C at ˜40 bar, where methane and some H2O are expelled from the region between the silicate layers (interlayer). In contrast, methane hydrates do not dissociate at these low temperatures. We conclude that at conditions similar to where methane hydrate is stable, smectite may intercalate with methane hydrate and provide additional sinks for methane. The limitation in the stability of smectite methane hydrate intercalate at low temperatures suggests that, if present in large quantities, it may release at decreasing temperatures sufficient methane to ameliorate a planetary cooling event.

  19. Fundamentals and applications of gas hydrates.

    PubMed

    Koh, Carolyn A; Sloan, E Dendy; Sum, Amadeu K; Wu, David T

    2011-01-01

    Fundamental understanding of gas hydrate formation and decomposition processes is critical in many energy and environmental areas and has special importance in flow assurance for the oil and gas industry. These areas represent the core of gas hydrate applications, which, albeit widely studied, are still developing as growing fields of research. Discovering the molecular pathways and chemical and physical concepts underlying gas hydrate formation potentially can lead us beyond flowline blockage prevention strategies toward advancing new technological solutions for fuel storage and transportation, safely producing a new energy resource from natural deposits of gas hydrates in oceanic and arctic sediments, and potentially facilitating effective desalination of seawater. The state of the art in gas hydrate research is leading us to new understanding of formation and dissociation phenomena that focuses on measurement and modeling of time-dependent properties of gas hydrates on the basis of their well-established thermodynamic properties.

  20. Evolution of the internal dynamics of two globular proteins from dry powder to solution.

    PubMed Central

    Pérez, J; Zanotti, J M; Durand, D

    1999-01-01

    Myoglobin and lysozyme picosecond internal dynamics in solution is compared to that in hydrated powders by quasielastic incoherent neutron scattering. This technique is sensitive to the motions of the nonexchangeable hydrogen atoms in a sample. Because these are homogeneously distributed throughout the protein structure, the average dynamics of the protein is described. We first propose an original data treatment to deal with the protein global motions in the case of solution samples. The validity of this treatment is checked by comparison with classical measurements of the diffusion constants. The evolution with the scattering vector of the width and relative contribution of the quasielastic component was then used to derive information on the amount of local diffusive motions and their characteristic average relaxation time. From dry powder to coverage by one water layer, the surface side chains progressively acquire the possibility to diffuse locally. On subsequent hydration, the main effect of water is to improve the rate of these diffusive motions. Motions with higher average amplitude occur in solution, about three times more than for a hydrated powder at complete coverage, with a shorter average relaxation time, approximately 4.5 ps compared to 9.4 ps for one water monolayer. PMID:10388771

  1. Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxide—calcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Christensen, Axel Nørlund; Jensen, Torben R.; Hanson, Jonathan C.

    2004-06-01

    In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 4·2H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 7·19H 2O. Ettringite is formed if sufficient CaSO 4·2H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 4·2H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170°C using in situ synchrotron X-ray powder diffraction. This technique allows the study of very fast chemical reactions that are observed here under hydrothermal conditions. A new experimental approach was developed to perform in situ mixing of the reactants during X-ray data collection.

  2. Rapid determination of melamine and cyanuric acid in milk powder using direct analysis in real time-time-of-flight mass spectrometry.

    PubMed

    Vaclavik, Lukas; Rosmus, Jan; Popping, Bert; Hajslova, Jana

    2010-06-18

    The use of fast semi-automated method employing direct analysis in real time (DART) ion source coupled to time-of-flight mass spectrometry (TOFMS) for analysis of melamine (MEL) and cyanuric acid (CYA) in milk powder and milk based products has been demonstrated in this study. Simple sample extraction procedure employing methanol-5% aqueous formic acid mixture, which enabled disruption of melamine-cyanurate complex, was followed by direct, high-throughput (30s per run) examination of sample extracts spread on a glass rod by mass spectrometry under ambient conditions, without any prior chromatographic separation. After optimization of instrument parameter settings, limits of detection (LODs) 170 and 450microgkg(-1) were achieved for MEL and CYA, respectively. In the final phase of study, the possibility of minimizing spectral interference, thus improving method performance characteristics through the use of ultrahigh resolving power offered by Orbitrap based mass analyzer is demonstrated.

  3. Shock-induced chemical reactions in titanium{endash}silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    SciTech Connect

    Thadhani, N.N.; Graham, R.A.; Royal, T.; Dunbar, E.; Anderson, M.U.; Holman, G.T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models. {copyright} {ital 1997 American Institute of Physics.}

  4. Shock-induced chemical reactions in titanium-silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    NASA Astrophysics Data System (ADS)

    Thadhani, N. N.; Graham, R. A.; Royal, T.; Dunbar, E.; Anderson, M. U.; Holman, G. T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models.

  5. Kinetic Stability of MOF-5 in Humid Environments: Impact of Powder Densification, Humidity Level, and Exposure Time.

    PubMed

    Ming, Yang; Purewal, Justin; Yang, Jun; Xu, Chunchuan; Soltis, Rick; Warner, James; Veenstra, Mike; Gaab, Manuela; Müller, Ulrich; Siegel, Donald J

    2015-05-05

    Metal-organic frameworks (MOFs) are an emerging class of microporous, crystalline materials with potential applications in the capture, storage, and separation of gases. Of the many known MOFs, MOF-5 has attracted considerable attention because of its ability to store gaseous fuels at low pressure with high densities. Nevertheless, MOF-5 and several other MOFs exhibit limited stability upon exposure to reactive species such as water. The present study quantifies the impact of humid air exposure on the properties of MOF-5 as a function of exposure time, humidity level, and morphology (i.e., powders vs pellets). Properties examined include hydrogen storage capacity, surface area, and crystallinity. Water adsorption/desorption isotherms are measured using a gravimetric technique; the first uptake exhibits a type V isotherm with a sudden increase in uptake at ∼50% relative humidity. For humidity levels below this threshold only minor degradation is observed for exposure times up to several hours, suggesting that MOF-5 is more stable than generally assumed under moderately humid conditions. In contrast, irreversible degradation occurs in a matter of minutes for exposures above the 50% threshold. Fourier transform infrared spectroscopy indicates that molecular and/or dissociated water is inserted into the skeletal framework after long exposure times. Densification into pellets can slow the degradation of MOF-5 significantly, and may present a pathway to enhance the stability of some MOFs.

  6. Glycine zinc sulfate penta-hydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction.

    PubMed

    Fortes, A Dominic; Howard, Christopher M; Wood, Ian G; Gutmann, Matthias J

    2016-10-01

    Single crystals of glycine zinc sulfate penta-hydrate [systematic name: hexa-aqua-zinc tetra-aquadiglycinezinc bis-(sulfate)], [Zn(H2O)6][Zn(C2H5NO2)2(H2O)4](SO4)2, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octa-hedra on sites of symmetry -1 and two SO4 tetra-hedra with site symmetry 1; the octa-hedra comprise one [tetra-aqua-diglycine zinc](2+) ion (centred on one Zn atom) and one [hexa-aqua-zinc](2+) ion (centred on the other Zn atom); the glycine zwitterion, NH3(+)CH2COO(-), adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N-H⋯O hydrogen bonds between the amine and carboxyl-ate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate inter-nuclear X-H (X = N, O) bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework.

  7. An X-ray diffraction analysis of crystallised whey and whey-permeate powders.

    PubMed

    Nijdam, Justin; Ibach, Alexander; Eichhorn, Klaus; Kind, Matthias

    2007-11-26

    Amorphous whey, whey-permeate and lactose powders have been crystallised at various air temperatures and humidities, and these crystallised powders have been examined using X-ray diffraction. The most stable lactose crystal under normal storage conditions, alpha-lactose monohydrate, forms preferentially in whey and whey-permeate powders at 50 degrees C, provided sufficient moisture is available, whereas anhydrous beta-lactose and mixed anhydrous lactose crystals, which are unstable under normal storage conditions, form preferentially at 90 degrees C. Thus, faster crystallisation at higher temperatures is offset by the formation of lactose-crystal forms that are less stable under normal storage conditions. Very little alpha-lactose monohydrate crystallised in the pure lactose powders over the range of temperatures and humidities tested, because the crystallisation of alpha- and beta-lactose is considerably more rapid than the mutarotation of beta- to alpha-lactose in the amorphous phase and the hydration of alpha-lactose during crystallisation. Protein and salts hinder the crystallisation process, which provides more time for mutarotation and crystal hydration in the whey and whey-permeate powders.

  8. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data

    PubMed Central

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L.; Dronskowski, Richard

    2015-01-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages. PMID:26664340

  9. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data.

    PubMed

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2015-12-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages.

  10. Natural gas hydrate occurrence and issues

    USGS Publications Warehouse

    Kvenvolden, K.A.

    1994-01-01

    Naturally occurring gas hydrate is found in sediment of two regions: (1) continental, including continental shelves, at high latitudes where surface temperatures are very cold, and (2) submarine outer continental margins where pressures are very high and bottom-water temperatures are near 0??C. Continental gas hydrate is found in association with onshore and offshore permafrost. Submarine gas hydrate is found in sediment of continental slopes and rises. The amount of methane present in gas hydrate is thought to be very large, but the estimates that have been made are more speculative than real. Nevertheless, at the present time there has been a convergence of ideas regarding the amount of methane in gas hydrate deposits worldwide at about 2 x 1016 m3 or 7 x 1017 ft3 = 7 x 105 Tcf [Tcf = trillion (1012) ft3]. The potentially large amount of methane in gas hydrate and the shallow depth of gas hydrate deposits are two of the principal factors driving research concerning this substance. Such a large amount of methane, if it could be commercially produced, provides a potential energy resource for the future. Because gas hydrate is metastable, changes of surface pressure and temperature affect its stability. Destabilized gas hydrate beneath the sea floor leads to geologic hazards such as submarine mass movements. Examples of submarine slope failures attributed to gas hydrate are found worldwide. The metastability of gas hydrate may also have an effect on climate. The release of methane, a 'greenhouse' gas, from destabilized gas hydrate may contribute to global warming and be a factor in global climate change.

  11. Compound Natural Gas Hydrate: A Natural System for Separation of Hydrate-Forming Gases

    NASA Astrophysics Data System (ADS)

    Max, M. D.; Osegovic, J. P.

    2007-12-01

    Natural processes that separate materials from a mixture may exert a major influence on the development of the atmospheres and surfaces of planets, moons, and other planetary bodies. Natural distillation and gravity separation, amongst others, are well known means of differentiating materials through liquid-gas partitioning. One of the least known attributes of clathrate (gas) hydrates is their potential effect on the evolution of planetary system oceans and atmospheres. Gas hydrates separate gases from mixtures of gases by concentrating preferred hydrate-forming materials (HFM) guests within the water-molecule cage structure of crystalline hydrate. Different HFMs have very different fields of stability. When multiple hydrate formers are present, a preference series based on their selective uptake exists. Compound hydrate, which is formed from two or more species of HFM, extract preferred HFM from a mixture in very different proportions to their relative percentages of the original mixture. These compound hydrates can have different formation and dissociation conditions depending on the evolution of the environment. That is, the phase boundary of the compound hydrate that is required for dissociation lies along a lower pressure - higher temperature course. Compound hydrates respond to variations in temperature, pressure, and HFM composition. On Earth, the primary naturally occurring hydrate of interest to global climate modeling is methane hydrate. Oceanic hydrate on Earth is the largest store of carbon in the biosphere that is immediately reactive to environmental change, and is capable of releasing large amounts of methane into the atmosphere over a short geological time span. Hydrate formation is essentially metastable and is very sensitive to environmental change and to gas flux. Where natural variations in temperature and pressure varies so that hydrate will form and dissociate in some cyclical manner, such as in oceans where sea level is capable of rising and

  12. Development of hydrate risk quantification in oil and gas production

    NASA Astrophysics Data System (ADS)

    Chaudhari, Piyush N.

    Subsea flowlines that transport hydrocarbons from wellhead to the processing facility face issues from solid deposits such as hydrates, waxes, asphaltenes, etc. The solid deposits not only affect the production but also pose a safety concern; thus, flow assurance is significantly important in designing and operating subsea oil and gas production. In most subsea oil and gas operations, gas hydrates form at high pressure and low temperature conditions, causing the risk of plugging flowlines, with a undesirable impact on production. Over the years, the oil and gas industry has shifted their perspective from hydrate avoidance to hydrate management given several parameters such as production facility, production chemistry, economic and environmental concerns. Thus, understanding the level of hydrate risk associated with subsea flowlines is an important in developing efficient hydrate management techniques. In the past, hydrate formation models were developed for various flow-systems (e.g., oil dominated, water dominated, and gas dominated) present in the oil and gas production. The objective of this research is to extend the application of the present hydrate prediction models for assessing the hydrate risk associated with subsea flowlines that are prone to hydrate formation. It involves a novel approach for developing quantitative hydrate risk models based on the conceptual models built from the qualitative knowledge obtained from experimental studies. A comprehensive hydrate risk model, that ranks the hydrate risk associated with the subsea production system as a function of time, hydrates, and several other parameters, which account for inertial, viscous, interfacial forces acting on the flow-system, is developed for oil dominated and condensate systems. The hydrate plugging risk for water dominated systems is successfully modeled using The Colorado School of Mines Hydrate Flow Assurance Tool (CSMHyFAST). It is found that CSMHyFAST can be used as a screening tool in

  13. Amorphization of sugar hydrates upon milling.

    PubMed

    Willart, J F; Dujardin, N; Dudognon, E; Danède, F; Descamps, M

    2010-07-19

    The possibility to amorphize anhydrous crystalline sugars, like lactose, trehalose and glucose, by mechanical milling was previously reported. We test here the possibility to amorphize the corresponding crystalline hydrates: lactose monohydrate, trehalose dihydrate and glucose monohydrate using fully identical milling procedures. The results show that only the first hydrate amorphizes while the other two remain structurally invariant. These different behaviours are attributed to the plasticizing effect of the structural water molecules which can decrease the glass transition temperature below the milling temperature. The results reveal clearly the fundamental role of the glass transition in the solid-state amorphization process induced by milling, and they also explain why crystalline hydrates are systematically more difficult to amorphize by milling than their anhydrous counterpart. The investigations have been performed by differential scanning calorimetry and powder X-ray diffraction.

  14. The crystal structure of lueshite at 298 K resolved by high-resolution time-of-flight neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Kennedy, Brendan J.; Knight, Kevin S.

    2017-06-01

    Refinement of time-of-flight high-resolution neutron powder diffraction data for lueshite (Na, Ca)(Nb, Ta, Ti)O3, the natural analogue of synthetic NaNbO3, demonstrates that lueshite at room temperature (298 K) adopts an orthorhombic structure with a 2a p × 2a p × 4a p superlattice described by space group Pmmn [#59: a = 7.8032(4) Å; b = 7.8193(4) Å; c = 15.6156(9) Å]. This structure is analogous to that of phase S of synthetic NaNbO3 observed at 753-783 K (480-510 °C). In common with synthetic NaNbO3, lueshite exhibits a series of phase transitions with decreasing temperature from a cubic (Pm\\bar{3}m ) aristotype through tetragonal (P4/mbm) and orthorhombic (Cmcm) structures. However, the further sequence of phase transitions differs in that for lueshite the series terminates with the room temperature S (Pmmn) phase, and the R (Pmmn or Pnma) and P (Pbcm) phases of NaNbO3 are not observed. The appearance of the S phase in lueshite at a lower temperature, relative to that of NaNbO3, is attributable to the effects of solid solution of Ti, Ta and Ca in lueshite.

  15. Methane storage in dry water gas hydrates.

    PubMed

    Wang, Weixing; Bray, Christopher L; Adams, Dave J; Cooper, Andrew I

    2008-09-03

    Dry water stores 175 v(STP)/v methane at 2.7 MPa and 273.2 K in a hydrate form which is close to the Department of Energy volumetric target for methane storage. Dry water is a silica-stabilized free-flowing powder (95% wt water), and fast methane uptakes were observed (90% saturation uptake in 160 min with no mixing) as a result of the relatively large surface-to-volume ratio of this material.

  16. DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

    NASA Astrophysics Data System (ADS)

    Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

    2016-03-01

    Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

  17. Increasing Gas Hydrate Formation Temperature for Desalination of High Salinity Produced Water with Secondary Guests

    SciTech Connect

    Cha, Jong-Ho; Seol, Yongkoo

    2013-10-07

    We suggest a new gas hydrate-based desalination process using water-immiscible hydrate formers; cyclopentane (CP) and cyclohexane (CH) as secondary hydrate guests to alleviate temperature requirements for hydrate formation. The hydrate formation reactions were carried out in an isobaric condition of 3.1 MPa to find the upper temperature limit of CO2 hydrate formation. Simulated produced water (8.95 wt % salinity) mixed with the hydrate formers shows an increased upper temperature limit from -2 °C for simple CO2 hydrate to 16 and 7 °C for double (CO2 + CP) and (CO2 + CH) hydrates, respectively. The resulting conversion rate to double hydrate turned out to be similar to that with simple CO2 hydrate at the upper temperature limit. Hydrate formation rates (Rf) for the double hydrates with CP and CH are shown to be 22 and 16 times higher, respectively, than that of the simple CO2 hydrate at the upper temperature limit. Such mild hydrate formation temperature and fast formation kinetics indicate increased energy efficiency of the double hydrate system for the desalination process. Dissociated water from the hydrates shows greater than 90% salt removal efficiency for the hydrates with the secondary guests, which is also improved from about 70% salt removal efficiency for the simple hydrates.

  18. Coupling of the hydration water dynamics and the internal dynamics of actin detected by quasielastic neutron scattering

    SciTech Connect

    Fujiwara, Satoru; Plazanet, Marie; Oda, Toshiro

    2013-02-15

    Highlights: ► Quasielastic neutron scattering spectra of F-actin and G-actin were measured. ► Analysis of the samples in D{sub 2}O and H{sub 2}O provided the spectra of hydration water. ► The first layer hydration water around F-actin is less mobile than around G-actin. ► This difference in hydration water is in concert with the internal dynamics of actin. ► Water outside the first layer behaves bulk-like but influenced by the first layer. -- Abstract: In order to characterize dynamics of water molecules around F-actin and G-actin, quasielastic neutron scattering experiments were performed on powder samples of F-actin and G-actin, hydrated either with D{sub 2}O or H{sub 2}O, at hydration ratios of 0.4 and 1.0. By combined analysis of the quasielastic neutron scattering spectra, the parameter values characterizing the dynamics of the water molecules in the first hydration layer and those of the water molecules outside of the first layer were obtained. The translational diffusion coefficients (D{sub T}) of the hydration water in the first layer were found to be 1.2 × 10{sup −5} cm{sup 2}/s and 1.7 × 10{sup −5} cm{sup 2}/s for F-actin and G-actin, respectively, while that for bulk water was 2.8 × 10{sup −5} cm{sup 2}/s. The residence times were 6.6 ps and 5.0 ps for F-actin and G-actin, respectively, while that for bulk water was 0.62 ps. These differences between F-actin and G-actin, indicating that the hydration water around G-actin is more mobile than that around F-actin, are in concert with the results of the internal dynamics of F-actin and G-actin, showing that G-actin fluctuates more rapidly than F-actin. This implies that the dynamics of the hydration water is coupled to the internal dynamics of the actin molecules. The D{sub T} values of the water molecules outside of the first hydration layer were found to be similar to that of bulk water though the residence times are strongly affected by the first hydration layer. This supports the

  19. Gas hydrate and humans

    USGS Publications Warehouse

    Kvenvolden, K.A.

    2000-01-01

    The potential effects of naturally occurring gas hydrate on humans are not understood with certainty, but enough information has been acquired over the past 30 years to make preliminary assessments possible. Three major issues are gas hydrate as (1) a potential energy resource, (2) a factor in global climate change, and (3) a submarine geohazard. The methane content is estimated to be between 1015 to 1017 m3 at STP and the worldwide distribution in outer continental margins of oceans and in polar regions are significant features of gas hydrate. However, its immediate development as an energy resource is not likely because there are various geological constraints and difficult technological problems that must be solved before economic recovery of methane from hydrate can be achieved. The role of gas hydrate in global climate change is uncertain. For hydrate methane to be an effective greenhouse gas, it must reach the atmosphere. Yet there are many obstacles to the transfer of methane from hydrate to the atmosphere. Rates of gas hydrate dissociation and the integrated rates of release and destruction of the methane in the geo/hydro/atmosphere are not adequately understood. Gas hydrate as a submarine geohazard, however, is of immediate and increasing importance to humans as our industrial society moves to exploit seabed resources at ever-greater depths in the waters of our coastal oceans. Human activities and installations in regions of gas-hydrate occurrence must take into account the presence of gas hydrate and deal with the consequences of its presence.

  20. Molecular Dynamics of a Hydrated Collagen Peptide: Insights into Rotational Motion and Residence Times of Single-Water Bridges in Collagen.

    PubMed

    Tourell, Monique C; Momot, Konstantin I

    2016-12-15

    Magnetic resonance transverse spin relaxation time constants (T2) of water protons in ordered collagenous tissues are dependent on the orientation of the tissue relative to the static magnetic field. This dependence is commonly referred to as the magic angle (MA) effect and has been attributed to the restricted rotational motion of icelike water bridges in the hydrated triple-helix collagen molecule. Understanding of the molecular mechanism of the MA effect is important for clinical and research applications of magnetic resonance spectroscopy and imaging to tissues, such as articular cartilage, tendons, and ligaments. In this work, we have used molecular dynamics simulations to investigate the subnanosecond time scale dynamics of single-water bridges in a model collagen peptide. We ascertain the residence times and the patterns of restricted rotational motion of water molecules. The key findings are strongly anisotropic rotation patterns of water molecules at bridge sites and a dynamic, rather than icelike, nature of the single-water bridges within the individual triple-helix collagen molecule.

  1. Hydration-coupled dynamics in proteins studied by neutron scattering and NMR: the case of the typical EF-hand calcium-binding parvalbumin.

    PubMed

    Zanotti, J M; Bellissent-Funel, M C; Parello, J

    1999-05-01

    The influence of hydration on the internal dynamics of a typical EF-hand calciprotein, parvalbumin, was investigated by incoherent quasi-elastic neutron scattering (IQNS) and solid-state 13C-NMR spectroscopy using the powdered protein at different hydration levels. Both approaches establish an increase in protein dynamics upon progressive hydration above a threshold that only corresponds to partial coverage of the protein surface by the water molecules. Selective motions are apparent by NMR in the 10-ns time scale at the level of the polar lysyl side chains (externally located), as well as of more internally located side chains (from Ala and Ile), whereas IQNS monitors diffusive motions of hydrogen atoms in the protein at time scales up to 20 ps. Hydration-induced dynamics at the level of the abundant lysyl residues mainly involve the ammonium extremity of the side chain, as shown by NMR. The combined results suggest that peripheral water-protein interactions influence the protein dynamics in a global manner. There is a progressive induction of mobility at increasing hydration from the periphery toward the protein interior. This study gives a microscopic view of the structural and dynamic events following the hydration of a globular protein.

  2. Methane hydrate formation in confined nanospace can surpass nature.

    PubMed

    Casco, Mirian E; Silvestre-Albero, Joaquín; Ramírez-Cuesta, Anibal J; Rey, Fernando; Jordá, Jose L; Bansode, Atul; Urakawa, Atsushi; Peral, Inma; Martínez-Escandell, Manuel; Kaneko, Katsumi; Rodríguez-Reinoso, Francisco

    2015-03-02

    Natural methane hydrates are believed to be the largest source of hydrocarbons on Earth. These structures are formed in specific locations such as deep-sea sediments and the permafrost based on demanding conditions of high pressure and low temperature. Here we report that, by taking advantage of the confinement effects on nanopore space, synthetic methane hydrates grow under mild conditions (3.5 MPa and 2 °C), with faster kinetics (within minutes) than nature, fully reversibly and with a nominal stoichiometry that mimics nature. The formation of the hydrate structures in nanospace and their similarity to natural hydrates is confirmed using inelastic neutron scattering experiments and synchrotron X-ray powder diffraction. These findings may be a step towards the application of a smart synthesis of methane hydrates in energy-demanding applications (for example, transportation).

  3. The crystalline state of methylene blue: a zoo of hydrates.

    PubMed

    Rager, Timo; Geoffroy, André; Hilfiker, Rolf; Storey, John M D

    2012-06-14

    A re-investigation of the crystalline state of methylene blue has led to the identification of five different hydrates with clearly distinct structures. These include the already known pentahydrate, a hydrate with 2.2-2.3 equivalents of water, two dihydrates, and a monohydrate. Contrary to older reports, no trihydrate was found. The preparation and characterization of the hydrates as well as the transformations between them are reported. The applied analytical methods include X-ray powder diffraction (XRPD), infrared spectroscopy (ATR-IR), thermogravimetry (TGA), differential scanning calorimetry (DSC), dynamic water vapor sorption (DVS) and solution calorimetry (SolCal). A phase diagram of temperature vs. composition has been established, and the stability domains of the different hydrates as a function of water activity and temperature have been determined based on data from DSC, SolCal and suspension equilibration experiments. Four out of the five hydrates are thermodynamically stable within a certain range of temperature and humidity.

  4. Methane hydrate formation in confined nanospace can surpass nature

    DOE PAGES

    Casco, Mirian E.; Silvestre-Albero, Joaquín; Ramírez-Cuesta, Anibal J.; ...

    2015-03-02

    Natural methane hydrates are believed to be the largest source of hydrocarbons on Earth. These structures are formed in specific locations such as deep-sea sediments and the permafrost based on demanding conditions of high pressure and low temperature. We report that, by taking advantage of the confinement effects on nanopore space, synthetic methane hydrates grow under mild conditions (3.5 MPa and 2 degrees C), with faster kinetics (within minutes) than nature, fully reversibly and with a nominal stoichiometry that mimics nature. Furthermore, the formation of the hydrate structures in nanospace and their similarity to natural hydrates is confirmed using inelasticmore » neutron scattering experiments and synchrotron X-ray powder diffraction. Our findings may be a step towards the application of a smart synthesis of methane hydrates in energy-demanding applications (for example, transportation).« less

  5. Methane hydrate formation in confined nanospace can surpass nature

    SciTech Connect

    Casco, Mirian E.; Silvestre-Albero, Joaquín; Ramírez-Cuesta, Anibal J.; Rey, Fernando; Jordá, Jose L.; Bansode, Atul; Urakawa, Atsushi; Peral, Inma; Martínez-Escandell, Manuel; Kaneko, Katsumi; Rodríguez-Reinoso, Francisco

    2015-03-02

    Natural methane hydrates are believed to be the largest source of hydrocarbons on Earth. These structures are formed in specific locations such as deep-sea sediments and the permafrost based on demanding conditions of high pressure and low temperature. We report that, by taking advantage of the confinement effects on nanopore space, synthetic methane hydrates grow under mild conditions (3.5 MPa and 2 degrees C), with faster kinetics (within minutes) than nature, fully reversibly and with a nominal stoichiometry that mimics nature. Furthermore, the formation of the hydrate structures in nanospace and their similarity to natural hydrates is confirmed using inelastic neutron scattering experiments and synchrotron X-ray powder diffraction. Our findings may be a step towards the application of a smart synthesis of methane hydrates in energy-demanding applications (for example, transportation).

  6. Space and time resolved X-ray diffraction as a tool to image mesoporous transport of water in a weakly-hydrated swelling clay

    NASA Astrophysics Data System (ADS)

    Meheust, Y.; Hemmen, H.; Ramstad Alme, L.; Fossum, J. O.

    2010-12-01

    Imposing a humidity gradient between the two ends of a quasi-onedimensional temperature-controlled weakly-hydrated sample of synthetic swelling clay, we follow the transport of water in the material using X-ray diffraction. Indeed, the swelling clay grains are nano-layered, that is, they consist of stacks of individual 1 nm-thick clay particles. They have the ability to incorporate water molecules in the nano-porosity between the layers, causing the interlayer repetition distance (d-spacing) of the stacks to depend on temperature and on the humidity present in the surrounding meso-porosity. A first experiment performed under controlled constant temperature and controlled humidity level all around the sample, varying the ambient relative humidity by steps, allows us to map the monotonous evolution of the d-spacing as a function of the relative humidity surrounding the clay. The reproducibility and reliability of this relative humidity-controlled d-shift enables us to use d as a measure of the local humidity surrounding the clay particles in the second experiment, which addresses quasi-onedimensional water transport in the clay. In this second experiment, we map the d-spacing in space and time as water progresses along the sample, and are able to extract profiles of the relative humidity along the sample length. Their time evolution describes the transport of water through the mesoporous space inside the clay: we are using space- and time-resolved X-ray diffraction as a tool for imaging the humidity content of our clay sample in situ, in a non-invasive manner. An analysis of the measured humidity profiles based on the Boltzmann transform, under certain simplifying assumptions, yields a diffusive behavior that is either normal or possibly weakly anomalous. References: * G. Løvoll, B. Sandnes, Y. Méheust, K. J. Måløy, J. O. Fossum, G. J. da Silva, M. S. P. Mundim, R. Droppa, D. M. Fonseca, Dynamics of water intercalation fronts in a nano-layered synthetic silicate

  7. The characteristics of gas hydrates recovered from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Lu, H.; Lorenson, T.D.; Moudrakovski, I.L.; Ripmeester, J.A.; Collett, T.S.; Hunter, R.B.; Ratcliffe, C.I.

    2011-01-01

    Systematic analyses have been carried out on two gas hydrate-bearing sediment core samples, HYPV4, which was preserved by CH4 gas pressurization, and HYLN7, which was preserved in liquid-nitrogen, recovered from the BPXA-DOE-USGS Mount Elbert Stratigraphic Test Well. Gas hydrate in the studied core samples was found by observation to have developed in sediment pores, and the distribution of hydrate saturation in the cores imply that gas hydrate had experienced stepwise dissociation before it was stabilized by either liquid nitrogen or pressurizing gas. The gas hydrates were determined to be structure Type I hydrate with hydration numbers of approximately 6.1 by instrumentation methods such as powder X-ray diffraction, Raman spectroscopy and solid state 13C NMR. The hydrate gas composition was predominantly methane, and isotopic analysis showed that the methane was of thermogenic origin (mean ??13C=-48.6??? and ??D=-248??? for sample HYLN7). Isotopic analysis of methane from sample HYPV4 revealed secondary hydrate formation from the pressurizing methane gas during storage. ?? 2010 Elsevier Ltd.

  8. Application of singular value decomposition analysis to time-dependent powder diffraction data of an in-situ photodimerization reaction

    PubMed Central

    Mabied, Ahmed F.; Nozawa, Shunsuke; Hoshino, Manabu; Tomita, Ayana; Sato, Tokushi; Adachi, Shin-ichi

    2014-01-01

    Singular value decomposition (SVD) analysis has important applications for time-dependent crystallographic data, extracting significant information. Herein, a successful application of SVD analysis of time-resolved powder diffraction data over the course of an in-situ photodimerization reaction of anthracene derivatives is introduced. SVD revealed significant results in the case of 9-methylanthracene and 1-chloroanthracene. The results support the formation of the 9-methylanthracene stable dimer phase and suggest the existence of an excimer state. PMID:24763645

  9. Gas Hydrate Nucleation Processes

    NASA Astrophysics Data System (ADS)

    David, R. E.; Zatsepina, O.; Phelps, T. J.

    2003-12-01

    The onset of gas hydrate nucleation is greatly affected by the thermal history of the water that forms its lattice structure. Hydrate formation experiments were performed in a 72 liter pressure vessel by bubbling carbon dioxide through a 1 liter column at hydrate formation pressures (1.4 to 3.7 MPa) and temperatures (275.0 to 278.0 K) to quantify this effect. They show that when even a fraction ( e. g. 20 %) of the water in which hydrate has formed was recently frozen and thawed, the overpressurization for nucleation was reduced by an average of 50 % versus experiments performed in distilled water. In those experiments where a lower overpressure is present when hydrate nucleated, they tended to form on the surface of bubbles, whereas when a higher amount of overpressure was necessary for hydrate to nucleate, they appeared to form abruptly on bubble surfaces as well as from the bulk liquid phase. In approximation of classical nucleation, hydrate formation could be described as occurring by the spontaneous joining together of arising components of the hydrate lattice. In water that was frozen, and kept at a low temperature (< 275 K), molecular simulation models predict the predominance of water molecules organized as penatmeters, a possible subunit of the hydrate lattice. Our results suggest that in nature, initiation of hydrate formation may be strongly influenced by temperature dependant pre-structuring of water molecules prior to their contact with gas.

  10. Methane hydrates in nature - Current knowledge and challenges

    USGS Publications Warehouse

    Collett, Timothy S.

    2014-01-01

    Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

  11. Solubility of hematite revisited: effects of hydration.

    PubMed

    Jang, Je-Hun; Dempsey, Brian A; Burgos, William D

    2007-11-01

    Measured pH and dissolved ferric iron concentration ([Fe(III)diss]) in contact with well-characterized hematite indicated an equilibrium with hematite immediately after synthesis, but [Fe(III)diss] increased with hydration time to be consistent with the predicted solubility of goethite or hydrous ferric oxide (HFO), hydrated analogues of hematite. X-ray diffraction did not detect structural modification of hematite after 190 days of hydration, but Mössbauer spectroscopy detected hydration that penetrated several crystalline layers. When the hematite suspension was diluted with water, solids were invariably identified as hematite, but [Fe(III)diss] and pH indicated an equilibrium with goethite or HFO. This is the first experimental confirmation that the interfacial hydration of anhydrous hematite results in higher solubility than predicted by bulk thermodynamic properties of hematite. Correspondence of the results with previously published measurements and implications for environmental chemistry of ferric oxides are also discussed.

  12. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    PubMed

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  13. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction

    PubMed Central

    Fortes, A. Dominic

    2015-01-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å−1. The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter­atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter­leaved with planes of XO4 (X = Mo, W) tetra­hedra that are linked by chains of water mol­ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856–2860] but shows that the purported three-centred inter­action involving one of the water mol­ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred ‘linear’ hydrogen bond. PMID:26279871

  14. Hydration-dependent dynamics of human telomeric oligonucleotides in the picosecond timescale: a neutron scattering study.

    PubMed

    Sebastiani, F; Longo, M; Orecchini, A; Comez, L; De Francesco, A; Muthmann, M; Teixeira, S C M; Petrillo, C; Sacchetti, F; Paciaroni, A

    2015-07-07

    The dynamics of the human oligonucleotide AG3(T2AG3)3 has been investigated by incoherent neutron scattering in the sub-nanosecond timescale. A hydration-dependent dynamical activation of thermal fluctuations in weakly hydrated samples was found, similar to that of protein powders. The amplitudes of such thermal fluctuations were evaluated in two different exchanged wave-vector ranges, so as to single out the different contributions from intra- and inter-nucleotide dynamics. The activation energy was calculated from the temperature-dependent characteristic times of the corresponding dynamical processes. The trends of both amplitudes and activation energies support a picture where oligonucleotides possess a larger conformational flexibility than long DNA sequences. This additional flexibility, which likely results from a significant relative chain-end contribution to the average chain dynamics, could be related to the strong structural polymorphism of the investigated oligonucleotides.

  15. Hydration-dependent dynamics of human telomeric oligonucleotides in the picosecond timescale: A neutron scattering study

    SciTech Connect

    Sebastiani, F.; Comez, L.; Sacchetti, F.; Orecchini, A.; Petrillo, C.; Paciaroni, A.; De Francesco, A.; Teixeira, S. C. M.

    2015-07-07

    The dynamics of the human oligonucleotide AG{sub 3}(T{sub 2}AG{sub 3}){sub 3} has been investigated by incoherent neutron scattering in the sub-nanosecond timescale. A hydration-dependent dynamical activation of thermal fluctuations in weakly hydrated samples was found, similar to that of protein powders. The amplitudes of such thermal fluctuations were evaluated in two different exchanged wave-vector ranges, so as to single out the different contributions from intra- and inter-nucleotide dynamics. The activation energy was calculated from the temperature-dependent characteristic times of the corresponding dynamical processes. The trends of both amplitudes and activation energies support a picture where oligonucleotides possess a larger conformational flexibility than long DNA sequences. This additional flexibility, which likely results from a significant relative chain-end contribution to the average chain dynamics, could be related to the strong structural polymorphism of the investigated oligonucleotides.

  16. Hydration-dependent dynamics of human telomeric oligonucleotides in the picosecond timescale: A neutron scattering study

    NASA Astrophysics Data System (ADS)

    Sebastiani, F.; Longo, M.; Orecchini, A.; Comez, L.; De Francesco, A.; Muthmann, M.; Teixeira, S. C. M.; Petrillo, C.; Sacchetti, F.; Paciaroni, A.

    2015-07-01

    The dynamics of the human oligonucleotide AG3(T2AG3)3 has been investigated by incoherent neutron scattering in the sub-nanosecond timescale. A hydration-dependent dynamical activation of thermal fluctuations in weakly hydrated samples was found, similar to that of protein powders. The amplitudes of such thermal fluctuations were evaluated in two different exchanged wave-vector ranges, so as to single out the different contributions from intra- and inter-nucleotide dynamics. The activation energy was calculated from the temperature-dependent characteristic times of the corresponding dynamical processes. The trends of both amplitudes and activation energies support a picture where oligonucleotides possess a larger conformational flexibility than long DNA sequences. This additional flexibility, which likely results from a significant relative chain-end contribution to the average chain dynamics, could be related to the strong structural polymorphism of the investigated oligonucleotides.

  17. The effect of pressure on tricalcium silicate hydration at different temperatures and in the presence of retarding additives

    SciTech Connect

    Jupe, Andrew C.; Wilkinson, Angus P.; Funkhouser, Gary P.

    2012-07-25

    The hydration of tricalcium silicate (C{sub 3}S) is accelerated by pressure. However, the extent to which temperature and/or cement additives modify this effect is largely unknown. Time-resolved synchrotron powder diffraction has been used to study cement hydration as a function of pressure at different temperatures in the absence of additives, and at selected temperatures in the presence of retarding agents. The magnitudes of the apparent activation volumes for C{sub 3}S hydration increased with the addition of the retarders sucrose, maltodextrin, aminotri(methylenephosphonic acid) and an AMPS copolymer. Pressure was found to retard the formation of Jaffeite relative to the degree of C{sub 3}S hydration in high temperature experiments. For one cement slurry studied without additives, the apparent activation volume for C{sub 3}S hydration remained close to {approx} -28 cm{sup 3} mol{sup -1} over the range 25 to 60 C. For another slurry, there were possible signs of a decrease in magnitude at the lowest temperature examined.

  18. [The outcome of hydration in functional dysphonia].

    PubMed

    García Real, T; García Real, A; Díaz Román, T; Cañizo Fernández Roldán, A

    2002-01-01

    Functional dysphonia has high prevalence among professional voice users. Different aspects should be considered in vocal therapy. One of them is hydration. The aim of the present study is to assess the effect of hydration on a few aspect of vocal dysfunction. 75 subjects were distributed into three different groups. 23 participated as a control group, 27 received hydration treatment and 25 received hydration treatment plus voice training. Dryness, mucosity, phonatory effort, hoarseness, fundamental frequency (Fo), maximum phonatory time (MPT), time of speech and laryngeal status were the variables evaluated at time 0 and 14 days later, immediately after the completion of the treatment of each group. Statistical differences regarding dryness (p = 0.003) and hoarseness (p = 0.033) were found between the control group and the groups receiving treatment. There were no statistical differences in severity and frequency of variables measured at time 0 at 14 days later in the control group. However, all variables except laryngeal status, improved significantly in the groups receiving hydration alone. Only clinical variables improved in the combined group. These findings indicated a therapeutic benefit of hydration, with or without voice training, for functional dysphonia. Further studies using acoustic and stroboscopic analysis are required in order to define the effect of hydration on the compliance of glottic sphincter.

  19. Quantitative analysis of powdered caffeine products purchased from the Internet using liquid chromatography-quadrupole time-of-flight mass spectrometry.

    PubMed

    Beauchamp, Gillian A; Lin, Thomas; Zeng, William Z D; Hendrickson, Robert G; Gerona, Roy

    2016-01-01

    Powdered caffeine is sold on the Internet as a supplement. Severe toxicity and fatalities have been reported with use, but it is unclear if this toxicity was due to excessive dosing, mislabeled products, or adulterant stimulants. Our objective was to analyze the contents of commercially available powdered caffeine products in order to assess product purity and presence of additional ingredients, contaminants, or adulterants which may contribute to toxicity. A sample of nine powdered caffeine products was purchased from the Internet. Two sample replicates of each caffeine product were analyzed. Liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF/MS) was used to identify and quantify substances in the purchased products and purity of the compounds were calculated. Comparison of actual mass versus labeled mass of caffeine demonstrated a mean purity of 88.25% (SD 13.41%) and median purity of 90.1%. The products studied contained 1.6-5.3 g per teaspoon. Labeling on these products had limited instructions regarding how to measure the recommended dose. Powdered caffeine products that are readily available on the Internet contained relatively pure caffeine with no additional detected stimulants. High purity, small serving size, and lack of clear dosing instructions may place users at risk of toxicity.

  20. Origins of hydration lubrication.

    PubMed

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  1. Dynamics of hydration water in protein

    NASA Astrophysics Data System (ADS)

    Bellissent-Funel, M.-C.; Teixeira, J.; Bradley, K. F.; Chen, S. H.

    1992-06-01

    Incoherent quasi-elastic neutron scattering studies of in vivo deuterated C-phycocyanin, at different levels of hydration, have been made. We show that the mobility at high temperature, (sim 300 K) of the water molecules near the protein surface can be described by relatively simple models. At full hydration the high temperature data can be interpreted using a model where each water molecule is diffusing in a confined space of 3 Å in radius. At low hydration, and 298 K, the diffusional behaviour is typical of jump diffusion with a residence time 10 times larger than the one in bulk water at the same temperature.

  2. Sintering titanium powders

    SciTech Connect

    Gerdemann, Stephen J.; Alman, David E.

    2005-09-01

    Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics, with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

  3. Direct measurements of the interactions between clathrate hydrate particles and water droplets.

    PubMed

    Liu, Chenwei; Li, Mingzhong; Zhang, Guodong; Koh, Carolyn A

    2015-08-14

    Clathrate hydrate particle agglomeration is often considered to be one of the key limiting factors in plug formation. The hydrate particle-water interaction can play a critical role in describing hydrate agglomeration, yet is severely underexplored. Therefore, this work investigates the interactions between water droplets and cyclopentane hydrate particles using a micromechanical force (MMF) apparatus. Specifically, the effect of contact time, temperature/subcooling, contact area, and the addition of Sorbitane monooleate (Span 80) surfactant on the water droplet-hydrate particle interaction behavior are studied. The measurements indicate that hydrate formation during the measurement would increase the water-hydrate interaction force significantly. The results also indicate that the contact time, subcooling and concentration of cyclopentane, which determine the hydrate formation rate and hydrate amount, will affect the hydrate-water interaction force. In addition, the interaction forces also increase with the water-hydrate contact area. The addition of Span 80 surfactant induces a change in the hydrate morphology and renders the interfaces stable versus unstable (leading to coalescence), and the contact force can affect the hydrate-water interaction behavior significantly. Compared with the hydrate-hydrate cohesion force (measured in cyclopentane), the hydrate-water adhesion force is an order of magnitude larger. These new measurements can help to provide new and critical insights into the hydrate agglomeration process and potential strategies to control this process.

  4. In-situ characterization of gas hydrates

    NASA Astrophysics Data System (ADS)

    Moerz, T.; Brueckmann, W.; Linke, P.; Tuerkay, M.

    2003-04-01

    Gas hydrates are a dynamic reservoir in the marine carbon cycle and a periodically large and focussed source of methane probably constituting the largest carbon reservoir on earth. Therefore an important issue in gas hydrate research is the need for better tools to remotely estimate the volume and stability conditions of marine gas hydrate in the near sub-surface. It is also crucial to precisely determine the hydrate stability conditions in the near sub-surface, where gas hydrates are most susceptible to dissolution under changing P/T conditions. Our knowledge about the occurrence, spatial distribution, and life-cycle of gas hydrates in marine sediments is mainly derived from indirect geophysical and geochemical evidence. In a few instances gas hydrates have also been directly observed and sampled at the sea floor. For regional or global estimates of hydrate volumes and stability conditions however, new techniques for ground-truthing and calibration of geophysical, biological and geochemical methods are needed. During the OTEGA cruise with RV SONNE to Hydrate Ridge off Oregon a new device for in-situ characterization of gas hydrates was deployed and tested for the first time. The tool, HDSD (Hydrate Detection and Stability Determination) is being developed as part of Cooperative Research Center (SFB) 574 "Volatiles and Fluids in Subduction Zones". It is designed to identify and quantify small volumes of near-surface gas hydrate through continuous in-situ thermal and resistivity monitoring in a defined volume of sediment while it is slowly heated to destabilize gas hydrates embedded in it. In its current configuration HDSD is delivered to the seafloor by a video-guided GEOMAR BC Lander system. The sediment volume to be tested for the presence and abundance of gas hydrates is first isolated by a rectangular experiment chamber that is pushed into the upper 30cm of sediment. A "stinger", centrally mounted in the chamber and equipped with two arrays of sensors, provides

  5. Superfine powdered activated carbon (S-PAC) coatings on microfiltration membranes: Effects of milling time on contaminant removal and flux.

    PubMed

    Amaral, Pauline; Partlan, Erin; Li, Mengfei; Lapolli, Flavio; Mefford, O Thompson; Karanfil, Tanju; Ladner, David A

    2016-09-01

    In microfiltration processes for drinking water treatment, one method of removing trace contaminants is to add powdered activated carbon (PAC). Recently, a version of PAC called superfine PAC (S-PAC) has been under development. S-PAC has a smaller particle size and thus faster adsorption kinetics than conventionally sized PAC. Membrane coating performance of various S-PAC samples was evaluated by measuring adsorption of atrazine, a model micropollutant. S-PACs were created in-house from PACs of three different materials: coal, wood, and coconut shell. Milling time was varied to produce S-PACs pulverized with different amounts of energy. These had different particles sizes, but other properties (e.g. oxygen content), also differed. In pure water the coal based S-PACs showed superior atrazine adsorption; all milled carbons had over 90% removal while the PAC had only 45% removal. With addition of calcium and/or NOM, removal rates decreased, but milled carbons still removed more atrazine than PAC. Oxygen content and specific external surface area (both of which increased with longer milling times) were the most significant predictors of atrazine removal. S-PAC coatings resulted in loss of filtration flux compared to an uncoated membrane and smaller particles caused more flux decline than larger particles; however, the data suggest that NOM fouling is still more of a concern than S-PAC fouling. The addition of calcium improved the flux, especially for the longer-milled carbons. Overall the data show that when milling S-PAC with different levels of energy there is a tradeoff: smaller particles adsorb contaminants better, but cause greater flux decline. Fortunately, an acceptable balance may be possible; for example, in these experiments the coal-based S-PAC after 30 min of milling achieved a fairly high atrazine removal (overall 80%) with a fairly low flux reduction (under 30%) even in the presence of NOM. This suggests that relatively short duration (low energy

  6. Conditions for Fromation of Oceanic Natural Gas Hydrate Deposits

    NASA Astrophysics Data System (ADS)

    Max, M. M.

    2005-12-01

    Despite the widespread nature of oceanic natural gas hydrate and associated gas concentrations on continental margins, natural gas hydrate has yet to be proven to be an economically viable unconventional gas resource. In part, this is because unequivocal models for the formation of economic hydrate deposits do not yet exist and there is no exploration methodology for identifying the high-grade hydrate sweet spots that will constitute economic hydrate deposits. At this time, it appears that the most commercially viable high-grade hydrate deposits consist of naturally permeable strata that hosts a high proportion of solid hydrate filling of original porosity. The different means by which hydrate grows and the optimum conditions for the maintenance of a strong growth dynamic provide a key to predicting the location of potential hydrate deposits. Hydrate has been produced from natural seawater, which is a close approximation of connate water in marine sediments, and a variety of Hydrate Forming Gases (HFG) using several different types of crystallizers in laboratory experiments. The crystallizers have been developed to test a broad range of hydrate growth conditions by controlling pressure, temperature (or temperature gradients), and HFG saturation levels. Growth has been achieved in both aqueous and gaseous media. These results provide insight into formation of natural gas hydrate and may constrain the search for economic hydrate deposits Natural gas hydrate forms in one of three main growth modes in aqueous media; mineralizing solutions, diffusion in aqueous media, and solid diffusion. When the relative potential for growth of these modes are assessed along with geological and ground (pore) water provincing, the most likely locations within the gas hydrate stability zone (GHSZ) for recoverable hydrate natural gas deposits may be identified. The most rapid mode for growth of solid hydrate takes place on the seafloor in the presence of venting. Natural gas-rich fluids

  7. Map of Hydrated Minerals on Vesta

    NASA Image and Video Library

    2012-09-26

    This map from NASA Dawn mission indicates the presence of hydrated minerals on the giant asteroid Vesta about 30 degrees north latitude, in August 2011. At the time, it was winter in Vesta northern hemisphere.

  8. Rapid identification of Bacillus anthracis spores in suspicious powder samples by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

    PubMed

    Dybwad, Marius; van der Laaken, Anton L; Blatny, Janet Martha; Paauw, Armand

    2013-09-01

    Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory-based matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis method for identifying B. anthracis spores in suspicious powder samples. A reference library containing 22 different Bacillus sp. strains or hoax materials was constructed and coupled with a novel classification algorithm and standardized processing protocol for various powder samples. The method's limit of B. anthracis detection was determined to be 2.5 × 10(6) spores, equivalent to a 55-μg sample size of the crudest B. anthracis-containing powder discovered during the 2001 Amerithrax incidents. The end-to-end analysis method was able to successfully discriminate among samples containing B. anthracis spores, closely related Bacillus sp. spores, and commonly encountered hoax materials. No false-positive or -negative classifications of B. anthracis spores were observed, even when the analysis method was challenged with a wide range of other bacterial agents. The robustness of the method was demonstrated by analyzing samples (i) at an external facility using a different MALDI-TOF MS instrument, (ii) using an untrained operator, and (iii) using mixtures of Bacillus sp. spores and hoax materials. Taken together, the observed performance of the analysis method developed demonstrates its potential applicability as a rapid, specific, sensitive, robust, and cost-effective laboratory-based analysis tool for resolving incidents involving suspicious powders in less than 30 min.

  9. Rapid Identification of Bacillus anthracis Spores in Suspicious Powder Samples by Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS)

    PubMed Central

    van der Laaken, Anton L.; Blatny, Janet Martha; Paauw, Armand

    2013-01-01

    Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory-based matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis method for identifying B. anthracis spores in suspicious powder samples. A reference library containing 22 different Bacillus sp. strains or hoax materials was constructed and coupled with a novel classification algorithm and standardized processing protocol for various powder samples. The method's limit of B. anthracis detection was determined to be 2.5 × 106 spores, equivalent to a 55-μg sample size of the crudest B. anthracis-containing powder discovered during the 2001 Amerithrax incidents. The end-to-end analysis method was able to successfully discriminate among samples containing B. anthracis spores, closely related Bacillus sp. spores, and commonly encountered hoax materials. No false-positive or -negative classifications of B. anthracis spores were observed, even when the analysis method was challenged with a wide range of other bacterial agents. The robustness of the method was demonstrated by analyzing samples (i) at an external facility using a different MALDI-TOF MS instrument, (ii) using an untrained operator, and (iii) using mixtures of Bacillus sp. spores and hoax materials. Taken together, the observed performance of the analysis method developed demonstrates its potential applicability as a rapid, specific, sensitive, robust, and cost-effective laboratory-based analysis tool for resolving incidents involving suspicious powders in less than 30 min. PMID:23811517

  10. Synergistic hydrate inhibition of monoethylene glycol with poly(vinylcaprolactam) in thermodynamically underinhibited system.

    PubMed

    Kim, Jakyung; Shin, Kyuchul; Seo, Yutaek; Cho, Seong Jun; Lee, Ju Dong

    2014-07-31

    This study investigates the hydrate inhibition performance of monoethylene glycol (MEG) with poly(vinylcaprolactam) (PVCap) for retarding the hydrate onset as well as preventing the agglomeration of hydrate particles. A high-pressure autoclave was used to determine the hydrate onset time, subcooling temperature, hydrate fraction in the liquid phase, and torque changes during hydrate formation in pure water, 0.2 wt % PVCap solution, and 20 and 30 wt % MEG solutions. In comparison to water with no inhibitors, the addition of PVCap delays the hydrate onset time but cannot reduce the hydrate fraction, leading to a sharp increase in torque. The 20 and 30 wt % MEG solutions also delay the hydrate onset time slightly and reduce the hydrate fraction to 0.15. The addition of 0.2 wt % PVCap to the 20 wt % MEG solution, however, delays the hydrate onset time substantially, and the hydrate fraction was less than 0.19. The torque changes were negligible during the hydrate formation, suggesting the homogeneous dispersion of hydrate particles in the liquid phase. The well-dispersed hydrate particles do not agglomerate or deposit under stirring. Moreover, when 0.2 wt % PVCap was added to the 30 wt % MEG solution, no hydrate formation was observed for at least 24 h. These results suggest that mixing of MEG with a small amount of PVCap in underinhibited conditions will induce the synergistic inhibition of hydrate by delaying the hydrate onset time as well as preventing the agglomeration and deposition of hydrate particles. Decreasing the hydrate fraction in the liquid phase might be the reason for negligible torque changes during the hydrate formation in the 0.2 wt % PVCap and 20 wt % MEG solution. Simple structure II was confirmed by in situ Raman spectroscopy for the synergistic inhibition system, while coexisting structures I and II are observed in 0.2 wt % PVCap solution.

  11. Measuring In situ Dissolved Methane Concentrations in Gas Hydrate-Rich Systems. Part 2: Investigating Mechanisms Controlling Hydrate Dissolution

    NASA Astrophysics Data System (ADS)

    Wilson, R. M.; Lapham, L.; Riedel, M.; Chanton, J.

    2010-12-01

    Methane is a potent greenhouse gas, twenty times more infrared-active than CO2, and an important energy source. For these reasons, methane hydrate, one of the largest potential reservoirs of methane on earth, is of considerable interest to scientists and industry alike. In particular, questions relating to the stability of methane hydrate are becoming more important as concern about the release of methane into overlying ocean (and eventually the atmosphere) and interest in the recovery of methane from this resource increase. Three primary factors control hydrate stability: pressure (P), temperature (T), and the gas concentration in the surrounding environment. Pressure and temperature govern the stability of the hydrate structure. When hydrate is exposed to P/T regimes outside of the stability zone (HSZ), the hydrate decomposes by dissociation, a relatively fast process resulting in the release of gaseous phase methane (CH4(g)). However, if the P/T regime is within the HSZ, but the concentration of the guest gas (typically CH4) in the surroundings is below saturation, the hydrate will decompose by dissolution resulting in a phase change between hydrate and the dissolved gas phase (CH4(aq)). OsmoSamplers were deployed at a methane hydrate outcrop in Barkley Canyon, Northern Cascadia Margin, collecting porewater samples in a gradient at 1cm increments away from the hydrate surface. Methane, ethane, and propane concentrations in the porewater samples were measured at 6-day resolution over a period of 9 months. At three centimeters from the hydrate face, methane concentrations were significantly lower than predicted saturation for conditions at this site. Curiously, in situ observations of natural hydrate dissolution are up to two orders of magnitude lower than predicted diffusion-controlled dissolution based on surrounding methane concentrations. Since diffusion of methane away from the hydrate surface has been implicated as the dominant control of hydrate dissolution

  12. Gas Hydrate Storage of Natural Gas

    SciTech Connect

    Rudy Rogers; John Etheridge

    2006-03-31

    Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a

  13. One role of hydration water in proteins: key to the "softening" of short time intraprotein collective vibrations of a specific length scale.

    PubMed

    Wang, Zhe; Chiang, Wei-Shan; Le, Peisi; Fratini, Emiliano; Li, Mingda; Alatas, Ahmet; Baglioni, Piero; Chen, Sow-Hsin

    2014-06-28

    High resolution inelastic X-ray scattering (IXS) experiments show that the "phonon energy softening" and "phonon population enhancement" observed in a hydrated native protein when increasing the temperature from 200 K to physiological temperature are not directly related to the protein structure. Such phenomena were also observed in a denatured sample without a defined tertiary structure and with a limited residual secondary structure. However, in a dry sample, such "softening" is strongly suppressed. These facts suggest that the above-mentioned protein "softening" phenomenon is water-induced. In addition, increasing the hydration level can also induce "phonon energy softening" at room temperature, but not at 200 K. This change may be due to a qualitative difference in the dynamics of hydration water at 200 K and at room temperature.

  14. Assessment of powder blend uniformity: Comparison of real-time NIR blend monitoring with stratified sampling in combination with HPLC and at-line NIR Chemical Imaging.

    PubMed

    Bakri, Barbara; Weimer, Marco; Hauck, Gerrit; Reich, Gabriele

    2015-11-01

    Scope of the study was (1) to develop a lean quantitative calibration for real-time near-infrared (NIR) blend monitoring, which meets the requirements in early development of pharmaceutical products and (2) to compare the prediction performance of this approach with the results obtained from stratified sampling using a sample thief in combination with off-line high pressure liquid chromatography (HPLC) and at-line near-infrared chemical imaging (NIRCI). Tablets were manufactured from powder blends and analyzed with NIRCI and HPLC to verify the real-time results. The model formulation contained 25% w/w naproxen as a cohesive active pharmaceutical ingredient (API), microcrystalline cellulose and croscarmellose sodium as cohesive excipients and free-flowing mannitol. Five in-line NIR calibration approaches, all using the spectra from the end of the blending process as reference for PLS modeling, were compared in terms of selectivity, precision, prediction accuracy and robustness. High selectivity could be achieved with a "reduced" approach i.e. API and time saving approach (35% reduction of API amount) based on six concentration levels of the API with three levels realized by three independent powder blends and the additional levels obtained by simply increasing the API concentration in these blends. Accuracy and robustness were further improved by combining this calibration set with a second independent data set comprising different excipient concentrations and reflecting different environmental conditions. The combined calibration model was used to monitor the blending process of independent batches. For this model formulation the target concentration of the API could be achieved within 3 min indicating a short blending time. The in-line NIR approach was verified by stratified sampling HPLC and NIRCI results. All three methods revealed comparable results regarding blend end point determination. Differences in both mean API concentration and RSD values could be

  15. High-temperature, high-pressure hydrothermal synthesis, crystal structure, and solid-state NMR spectroscopy of Cs2(UO2)(Si2O6) and variable-temperature powder X-ray diffraction study of the hydrate phase Cs2(UO2)(Si2O6) x 0.5H2O.

    PubMed

    Chen, Chih-Shan; Chiang, Ray-Kuang; Kao, Hsien-Ming; Lii, Kwang-Hwa

    2005-05-30

    A new uranium(VI) silicate, Cs2(UO2)(Si2O6), has been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It crystallizes in the orthorhombic space group Ibca (No. 73) with a = 15.137(1) A, b = 15.295(1) A, c = 16.401(1) A, and Z = 16. Its structure consists of corrugated achter single chains of silicate tetrahedra extending along the c axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework which delimits 8- and 6-ring channels. The Cs+ cations are located in the channels or at sites between channels. The 29Si and 133Cs MAS NMR spectra are consistent with the crystal structure as determined from X-ray diffraction, and the resonances in the spectra are assigned. Variable-temperature in situ powder X-ray diffraction study of the hydrate Cs2(UO2)(Si2O6) x 0.5H2O indicates that the framework structure is stable up to 800 degrees C and transforms to the structure of the title compound at 900 degrees C. A comparison of related uranyl silicate structures is made.

  16. Gas hydrate contribution to Late Permian global warming

    NASA Astrophysics Data System (ADS)

    Majorowicz, J.; Grasby, S. E.; Safanda, J.; Beauchamp, B.

    2014-05-01

    Rapid gas hydrate release (the “clathrate gun” hypothesis) has been invoked as a cause for the rapid global warming and associated negative carbon isotope excursion observed during the Latest Permian Extinction (LPE). We modeled the stability of gas hydrates through a warming Middle to Late Permian world, considering three settings for methane reservoirs: 1) terrestrial hydrates, 2) hydrates on exposed continental shelves during glacial sea level drop, and 3) hydrates in deep marine settings. Model results show that terrestrial hydrates would rapidly destabilize over ∼400 ky after deglaciation for moderate heatflow (40 mW/m2), and more rapidly for higher heat flow values. Exposed continental shelves would lose hydrates even more rapidly, after being flooded due to loss of ice storage on land. These two major hydrate reservoirs would thus have destabilized during the Middle to Late Permian climate warming, well prior to the LPE event. However, they may have contributed to the >2‰ negative C-isotopic shift during the late Middle Permian. Deep marine hydrates would have remained stable until LPE time. Rapid warming of deep marine waters during this time could have triggered destabilization of this reservoir, however given the configuration of one super continent, Pangea, hydrate bearing continental slopes would have been less extensive than modern day. This suggests that any potential gas hydrate release would have had only a minor contributing impact to the runaway greenhouse during the Latest Permian extinction.

  17. Effects of drying methods on the physicochemical and compressional characteristics of Okra powder and the release properties of its metronidazole tablet formulation.

    PubMed

    Bakre, L G; Jaiyeoba, K T

    2009-02-01

    A study has been made of the effects of sun and oven drying methods on the physicochemical characteristics and compressibility of Okra powder and the release properties of its metronidazole tablet formulation. Corn starch was used as the reference standard. The mechanical properties of the tablets were evaluated using crushing strength and friability, while the release properties were determined using the disintegration times and dissolution rates. The results obtained showed that sun-dried Okra powder had smaller particle size, exhibited good flow and possessed higher hydration and swelling capacities compared to the oven dried samples. The compressibility of Okra powders assessed by the indices of plasticity from Heckel (Py) and Kawakita plots (Pk) showed that sun dried Okra powders had higher Py but lower Pk values than the oven-dried Okra powder. Metronidazole tablets formulated with oven dried Okra powder formed stronger tablets than tablets containing sun dried Okra powder. Generally, tablets containing sun dried Okra powders had faster disintegration and dissolution than tablets formulated with oven-dried powder. The results suggest that the choice of drying method during the processing of pharmaceutical raw materials is critical to its physicochemical properties and the release properties of its tablet formulations.

  18. Devitrification of Mechanically Alloyed Zr-Ti-Nb-Cu-Ni-Al Glassy Powders Studied by Time-Resolved X-ray Diffraction

    SciTech Connect

    Scudino, S.; Sordelet, D.J.; Eckert, J.

    2009-04-13

    The crystallization of mechanically alloyed Zr{sub 67}Ti{sub 6.14}Nb{sub 1.92}Cu{sub 10.67}Ni{sub 8.52}Al{sub 5.75} glassy powder is investigated by time-resolved X-ray diffraction. The powder displays a multi-step crystallization behavior characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process. At higher temperatures, coinciding with the second crystallization event, the amorphous-to-quasicrystalline transformation is followed by the precipitation of the tetragonal Zr{sub 2}Cu phase (space group I4/mmm) and the tetragonal Zr{sub 2}Ni phase (space group I4/mcm). The transformations are gradual and the quasicrystals and the subsequent phases coexist over a temperature interval of about 25K.

  19. Production of coconut protein powder from coconut wet processing waste and its characterization.

    PubMed

    Naik, Aduja; Raghavendra, S N; Raghavarao, K S M S

    2012-07-01

    Virgin coconut oil (VCO) has been gaining popularity in recent times. During its production, byproducts such as coconut skim milk and insoluble protein are obtained which are underutilized or thrown away to the environment at present. This study deals with utilization of these byproducts to obtain a value-added product, namely, coconut protein powder. When coconut milk was subjected to centrifugation, three phases, namely, fat phase (coconut cream), aqueous phase (coconut skim milk), and solid phase (insoluble protein) were obtained. The coconut skim milk and insoluble protein were mixed and homogenized before spray drying to obtain a dehydrated protein powder. The proximate analysis of the powder showed high protein content (33 % w/w) and low fat content (3 % w/w). Protein solubility was studied as a function of pH and ionic content of solvent. Functional properties such as water hydration capacity, fat absorption capacity, emulsifying properties, wettability, and dispersibility of coconut protein powder were evaluated along with morphological characterization, polyphenol content, and color analysis. Coconut protein powder has shown to have good emulsifying properties and hence has potential to find applications in emulsified foods. Sensory analysis showed high overall quality of the product, indicating that coconut protein powder could be a useful food ingredient.

  20. Influence of temperature on methane hydrate formation.

    PubMed

    Zhang, Peng; Wu, Qingbai; Mu, Cuicui

    2017-08-11

    During gas hydrate formation process, a phase transition of liquid water exists naturally, implying that temperature has an important influence on hydrate formation. In this study, methane hydrate was formed within the same media. The experimental system was kept at 1.45, 6.49, and 12.91 °C respectively, and then different pressurization modes were applied in steps. We proposed a new indicator, namely the slope of the gas flow rates against time (dν g /dt), to represent the intrinsic driving force for hydrate formation. The driving force was calculated as a fixed value at the different stages of formation, including initial nucleation/growth, secondary nucleation/growth, and decay. The amounts of gas consumed at each stage were also calculated. The results show that the driving force during each stage follows an inverse relation with temperature, whereas the amount of consumed gas is proportional to temperature. This opposite trend indicates that the influences of temperature on the specific formation processes and final amounts of gas contained in hydrate should be considered separately. Our results also suggest that the specific ambient temperature under which hydrate is formed should be taken into consideration, when explaining the formation of different configurations and saturations of gas hydrates in natural reservoirs.

  1. Rapid gas hydrate formation processes: Will they work?

    SciTech Connect

    Brown, Thomas D.; Taylor, Charles E.; Bernardo, Mark P.

    2010-06-07

    Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with instrumentation to study rapid and continuous hydrate formation. The cells ranged in size from 100 mL for screening studies to proof-of-concept studies with NETL’s 15-Liter Hydrate Cell. The results from this work demonstrate that the rapid and continuous formation of methane hydrate is possible at predetermined temperatures and pressures within the stability zone of a Methane Hydrate Stability Curve.

  2. Rapid gas hydrate formation processes: Will they work?

    DOE PAGES

    Brown, Thomas D.; Taylor, Charles E.; Bernardo, Mark P.

    2010-06-07

    Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with instrumentation to study rapid and continuous hydrate formation. The cells ranged in size from 100 mL for screening studies to proof-of-concept studies with NETL’s 15-Liter Hydrate Cell. The results from this work demonstrate that the rapid and continuousmore » formation of methane hydrate is possible at predetermined temperatures and pressures within the stability zone of a Methane Hydrate Stability Curve.« less

  3. Complex dielectric properties of microcrystalline cellulose, anhydrous lactose, and α-lactose monohydrate powders using a microwave-based open-reflection resonator sensor.

    PubMed

    Sung, Pei-Fang; Hsieh, Yi-Ling; Angonese, Kristen; Dunn, Don; King, Ray J; Machbitz, Rachel; Christianson, Andrew; Chappell, William J; Taylor, Lynne S; Harris, Michael T

    2011-07-01

    The real (ε') and imaginary (ε″) components of the complex permittivity of anhydrous lactose and microcrystalline cellulose (MCC) under different bulk densities, moisture contents (MCs), and times of hydration (for anhydrous lactose) were measured nondestructively using a microwave resonator sensor operating in the range of 700-800 MHz. Measurements of sensor resonant frequency and conductance allow, through calibration, determination of the complex dielectric properties ε' (relative permittivity) and ε″ (relative dielectric loss) of the test material. Characteristic graphs of ε″ versus ε' - 1 curve for each powder were generated as a function of bulk density and MC. Such data can be used to develop empirical models for the simultaneous in situ measurement of the bulk density and MC of the powders. Unlike MCC, anhydrous lactose is converted to its hydrate form in the presence of moisture, which causes a reduction in the amount of physisorbed and "free" water and a subsequent change in the dielectric properties. For powders such as anhydrous lactose that can form a crystal hydrate in the presence of moisture, a combination of techniques such as vibrational spectroscopy together with microwave resonator measurements are appropriate to characterize, in situ, the physical and chemical properties of the powder.

  4. The hydration/dehydration behavior of aspartame revisited.

    PubMed

    Guguta, C; Meekes, H; de Gelder, R

    2008-03-13

    Aspartame, l-aspartyl-l-phenylalanine methyl ester, has two hydrates (IA and IB), a hemi-hydrate (IIA) and an anhydrate (IIB). The hydration/dehydration behavior of aspartame was investigated using hot-humidity stage X-ray powder diffraction (XRPD) and molecular mechanics modeling in combination with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of this study are compared to earlier studies on aspartame as described in literature. It is shown that earlier transition studies were hampered by incomplete conversions and wrong assignment of the forms. The combination of the techniques applied in this study now shows consistent results for aspartame and yields a clear conversion scheme for the hydration/dehydration behavior of the four forms.

  5. Hydration rate of obsidian.

    PubMed

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

  6. A method for rapid sampling and characterization of smokeless powder using sorbent-coated wire mesh and direct analysis in real time - mass spectrometry (DART-MS).

    PubMed

    Li, Frederick; Tice, Joseph; Musselman, Brian D; Hall, Adam B

    2016-09-01

    Improvised explosive devices (IEDs) are often used by terrorists and criminals to create public panic and destruction, necessitating rapid investigative information. However, backlogs in many forensic laboratories resulting in part from time-consuming GC-MS and LC-MS techniques prevent prompt analytical information. Direct analysis in real time - mass spectrometry (DART-MS) is a promising analytical technique that can address this challenge in the forensic science community by permitting rapid trace analysis of energetic materials. Therefore, we have designed a qualitative analytical approach that utilizes novel sorbent-coated wire mesh and dynamic headspace concentration to permit the generation of information rich chemical attribute signatures (CAS) for trace energetic materials in smokeless powder with DART-MS. Sorbent-coated wire mesh improves the overall efficiency of capturing trace energetic materials in comparison to swabbing or vacuuming. Hodgdon Lil' Gun smokeless powder was used to optimize the dynamic headspace parameters. This method was compared to traditional GC-MS methods and validated using the NIST RM 8107 smokeless powder reference standard. Additives and energetic materials, notably nitroglycerin, were rapidly and efficiently captured by the Carbopack X wire mesh, followed by detection and identification using DART-MS. This approach has demonstrated the capability of generating comparable results with significantly reduced analysis time in comparison to GC-MS. All targeted components that can be detected by GC-MS were detected by DART-MS in less than a minute. Furthermore, DART-MS offers the advantage of detecting targeted analytes that are not amenable to GC-MS. The speed and efficiency associated with both the sample collection technique and DART-MS demonstrate an attractive and viable potential alternative to conventional techniques.

  7. Transformations in methane hydrates

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Shu, J.; Mao, Ho-kwang; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2000-01-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A?? and volume V = 5051.3(13) A??3; structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A??, c = 9.992(3) A??, and V = 1241.9(5) A??3. The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

  8. Hydrate morphology: Physical properties of sands with patchy hydrate saturation

    USGS Publications Warehouse

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.

    2012-01-01

    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  9. Real-time high-resolution X-ray imaging and nuclear magnetic resonance study of the hydration of pure and Na-doped C3A in the presence of sulfates

    SciTech Connect

    Kirchheim,, A. P.; Dal Molin, D.C.; Emwas, Abdul-Hamid; Provis, J.L.; Fischer, P.; Monteiro, P.J.M.

    2010-12-01

    This study details the differences in real-time hydration between pure tricalcium aluminate (cubic C{sub 3}A or 3CaO {center_dot} Al{sub 2}O{sub 3}) and Na-doped tricalcium aluminate (orthorhombic C{sub 3}A or Na{sub 2}Ca{sub 8}Al{sub 6}O{sub 18}), in aqueous solutions containing sulfate ions. Pure phases were synthesized in the laboratory to develop an independent benchmark for the reactions, meaning that their reactions during hydration in a simulated early age cement pore solution (saturated with respect to gypsum and lime) were able to be isolated. Because the rate of this reaction is extremely rapid, most microscopy methods are not adequate to study the early phases of the reactions in the early stages. Here, a high-resolution full-field soft X-ray imaging technique operating in the X-ray water window, combined with solution analysis by {sup 27}Al nuclear magnetic resonance (NMR) spectroscopy, was used to capture information regarding the mechanism of C{sub 3}A hydration during the early stages. There are differences in the hydration mechanism between the two types of C{sub 3}A, which are also dependent on the concentration of sulfate ions in the solution. The reactions with cubic C{sub 3}A (pure) seem to be more influenced by higher concentrations of sulfate ions, forming smaller ettringite needles at a slower pace than the orthorhombic C{sub 3}A (Na-doped) sample. The rate of release of aluminate species into the solution phase is also accelerated by Na doping.

  10. Multipoint near-infrared spectrometry for real-time monitoring of protein conformational stability in powdered infant formula.

    PubMed

    Pabari, Ritesh M; Togashi, Denisio; Cama-Moncunill, Raquel; El Arnaout, Toufic; Rifai, Hicham; Cruise, Paul; Cullen, Patrick J; Sullivan, Carl

    2015-01-01

    Powdered infant formula (PIF) can be the sole source of nutrition for babies and infants. Monitoring conformational changes in protein during manufacture of PIF is critical in order to maintain its nutritional value. This study presents the development of a calibration model for monitoring conformational changes in PIF protein by applying a novel multipoint near-infrared (NIR) spectrometry. NIR spectra were collected for PIF and PIF proteins, casein and whey protein isolate, before and after heat treatment. Results show that principal component analysis showed discrimination between native protein at room temperature and protein conformational changes caused at elevated temperature. Partial least squares regression analysis showed good calibration models with correlation coefficients ranging between 87% and 99% for the prediction of protein quality. This novel multipoint NIR spectrometry could serve as a simple in-line tool to rapidly monitor protein quality during processing stages, contributing to product nutritional value.

  11. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy.

    PubMed

    Yang, Chao; Muránsky, Ondrej; Zhu, Hanliang; Thorogood, Gordon J; Avdeev, Maxim; Huang, Hefei; Zhou, Xingtai

    2017-04-06

    A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5-2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni₃Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo₂C particles during sintering. The amount of grain boundaries greatly increases the Hall-Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process.

  12. Isotope dilution mass spectrometry for quantitative elemental analysis of powdered samples by radiofrequency pulsed glow discharge time of flight mass spectrometry.

    PubMed

    Alvarez-Toral, Aitor; Fernandez, Beatriz; Malherbe, Julien; Claverie, Fanny; Molloy, John L; Pereiro, Rosario; Sanz-Medel, Alfredo

    2013-10-15

    In recent years particular effort is being devoted to the development of pulsed glow discharges (PGDs) for mass spectrometry because this powering operation mode could offer important ionization analytical advantages. However, the capabilities of radiofrequency (RF) PGD coupled to a time of flight mass spectrometry (ToFMS) for accurate isotope ratio measurements have not been demonstrated yet. This work is focused on investigating different time positions along the pulse profile for the accurate measurement of isotope ratios. As a result, a method has been developed for the direct and simultaneous multielement determination of trace elements in powdered geological samples by RF-PGD-ToFMS in combination with isotope dilution mass spectrometry (IDMS) as an absolute measurement method directly traceable to the International System of Units. Optimized operating conditions were 70 W of applied radiofrequency power, 250 Pa of pressure, 2 ms of pulse width and 4 ms of pulse period, being argon the plasma gas used. To homogeneously distribute the added isotopically-enriched standards, lithium borate fusion of powdered solid samples was used as sample preparation approach. In this way, Cu, Zn, Ba and Pb were successfully determined by RF-PGD-ToF(IDMS) in two NIST Standard Reference Materials (SRM 2586 and SRM 2780) representing two different matrices of geological interest (soil and rock samples). Cu, Zn, Ba and Pb concentrations determined by RF-PGD-ToF(IDMS) were well in agreement with the certified values at 95% confidence interval and precisions below 12% relative standard deviation were observed for three independent analyses. Elemental concentrations investigated were in the range of 81-5770 mg/kg, demonstrating the potential of RF-PGD-ToF(IDMS) for a sensitive, accurate and robust analysis of powdered samples.

  13. The Effect of Milling Time on the Microstructural Characteristics and Strengthening Mechanisms of NiMo-SiC Alloys Prepared via Powder Metallurgy

    PubMed Central

    Yang, Chao; Muránsky, Ondrej; Zhu, Hanliang; Thorogood, Gordon J.; Avdeev, Maxim; Huang, Hefei; Zhou, Xingtai

    2017-01-01

    A new generation of alloys, which rely on a combination of various strengthening mechanisms, has been developed for application in molten salt nuclear reactors. In the current study, a battery of dispersion and precipitation-strengthened (DPS) NiMo-based alloys containing varying amounts of SiC (0.5–2.5 wt %) were prepared from Ni-Mo-SiC powder mixture via a mechanical alloying (MA) route followed by spark plasma sintering (SPS) and rapid cooling. Neutron Powder Diffraction (NPD), Electron Back Scattering Diffraction (EBSD), and Transmission Electron Microscopy (TEM) were employed in the characterization of the microstructural properties of these in-house prepared NiMo-SiC DPS alloys. The study showed that uniformly-dispersed SiC particles provide dispersion strengthening, the precipitation of nano-scale Ni3Si particles provides precipitation strengthening, and the solid-solution of Mo in the Ni matrix provides solid-solution strengthening. It was further shown that the milling time has significant effects on the microstructural characteristics of these alloys. Increased milling time seems to limit the grain growth of the NiMo matrix by producing well-dispersed Mo2C particles during sintering. The amount of grain boundaries greatly increases the Hall–Petch strengthening, resulting in significantly higher strength in the case of 48-h-milled NiMo-SiC DPS alloys compared with the 8-h-milled alloys. However, it was also shown that the total elongation is considerably reduced in the 48-h-milled NiMo-SiC DPS alloy due to high porosity. The porosity is a result of cold welding of the powder mixture during the extended milling process. PMID:28772747

  14. Exploitation of subsea gas hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2016-04-01

    Natural gas hydrates are considered to be a potential energy resource in the future. They occur in permafrost areas as well as in subsea sediments and are stable at high pressure and low temperature conditions. According to estimations the amount of carbon bonded in natural gas hydrates worldwide is two times larger than in all known conventional fossil fuels. Besides technical challenges that have to be overcome climate and safety issues have to be considered before a commercial exploitation of such unconventional reservoirs. The potential of producing natural gas from subsea gas hydrate deposits by various means (e.g. depressurization and/or injection of carbon dioxide) is numerically studied in the frame of the German research project »SUGAR«. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into a numerical model. The physics of the process leads to strong non-linear couplings between hydraulic fluid flow, hydrate dissociation and formation, hydraulic properties of the sediment, partial pressures and seawater solution of components and the thermal budget of the system described by the heat equation. This paper is intended to provide an overview of the recent development regarding the production of natural gas from subsea gas hydrate reservoirs. It aims at giving a broad insight into natural gas hydrates and covering relevant aspects of the exploitation process. It is focused on the thermodynamic principles and technological approaches for the exploitation. The effects occurring during natural gas production within hydrate filled sediment layers are identified and discussed by means of numerical simulation results. The behaviour of relevant process parameters such as pressure, temperature and phase saturations is described and compared for different strategies. The simulations are complemented by calculations for different safety relevant problems.

  15. The hydration properties of carboxybetaine zwitterion brushes.

    PubMed

    Du, Hongbo; Qian, Xianghong

    2016-04-15

    Combined quantum mechanical calculations and classical molecular dynamics simulations were conducted to investigate the hydration properties of carboxybetaine zwitterion brushes with varying separation distances between the quaternary ammonium cation and carboxylic anion. The brushes consist of zwitterion trimers and are investigated to mimic interacting zwitterion chains grafted on a substrate as well as polymers with interacting zwitterion side chains. Our results show that the values of both positive and negative charges, their separation distances as well as chain interactions appear to play a critical role in the hydration properties of the zwitterions. The overall hydration property of these zwitterions is dictated by the competition between the strong hydration of the charged groups and the dehydration of the hydrocarbon chains. The strongest hydration occurs when the -CH2- unit in the hydrocarbon chain reaches 6-8 for these trimers. Further increase in the hydrocarbon chain length to 10-14 leads to significant and sudden dehydration of the trimers. The water structure and the water residence time surrounding the zwitterions also demonstrate substantial alteration at this length scale. This hydrophilic-to-hydrophobic transition is induced by the hydrophobic interactions of the trimer chains. Our hydration results could explain the observed trend of the superiority of the methylated carbohydrates and poly(ethylene glycol) as antifouling materials compared to corresponding hydroxyl-terminated compounds.

  16. Phase Transition of a Structure II Cubic Clathrate Hydrate to a Tetragonal Form.

    PubMed

    Takeya, Satoshi; Fujihisa, Hiroshi; Yamawaki, Hiroshi; Gotoh, Yoshito; Ohmura, Ryo; Alavi, Saman; Ripmeester, John A

    2016-08-01

    The crystal structure and phase transition of cubic structure II (sII) binary clathrate hydrates of methane (CH4 ) and propanol are reported from powder X-ray diffraction measurements. The deformation of host water cages at the cubic-tetragonal phase transition of 2-propanol+CH4 hydrate, but not 1-propanol+CH4 hydrate, was observed below about 110 K. It is shown that the deformation of the host water cages of 2-propanol+CH4 hydrate can be explained by the restriction of the motion of 2-propanol within the 5(12) 6(4) host water cages. This result provides a low-temperature structure due to a temperature-induced symmetry-lowering transition of clathrate hydrate. This is the first example of a cubic structure of the common clathrate hydrate families at a fixed composition.

  17. The impact of zirconium oxide radiopacifier on the early hydration behaviour of white Portland cement.

    PubMed

    Coleman, Nichola J; Li, Qiu

    2013-01-01

    Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), (29)Si and (27)Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases.

  18. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    SciTech Connect

    Deschner, Florian; Lothenbach, Barbara; Winnefeld, Frank; Neubauer, Jürgen

    2013-10-15

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H.

  19. Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

    DOE PAGES

    Chen, Sow-Hsin; Lagi, Marco; Chu, Xiang-qiang; ...

    2010-01-01

    This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling between them. We found that the key to this strong coupling is the existence of a fragile-to-strong dynamic crossover (FSC) phenomenon occurring at around T L = 225±5 K in the hydration water. On lowering of the temperature toward FSC, the structure of hydration water makes a transition from predominantly the high density form (HDL), a more fluid state, to predominantly the low density formmore » (LDL), a less fluid state, derived from the existence of a liquid–liquid critical point at an elevated pressure. We show experimentally that this sudden switch in the mobility of hydration water on Lysozyme, B-DNA and RNA triggers the dynamic transition, at a temperature T D = 220 K, for these biopolymers. In the glassy state, below T D , the biopolymers lose their vital conformational flexibility resulting in a substantial diminishing of their biological functions. We also performed molecular dynamics (MD) simulations on a realistic model of hydrated lysozyme powder, which confirms the existence of the FSC and the hydration level dependence of the FSC temperature. Furthermore, we show a striking feature in the short time relaxation ( β -relaxation) of protein dynamics, which is the logarithmic decay spanning 3 decades (from ps to ns). The long time α -relaxation shows instead a diffusive behavior, which supports the liquid-like motions of protein constituents. We then discuss our recent high-resolution X-ray inelastic scattering studies of globular proteins, Lysozyme and Bovine Serum Albumin. We were able to measure the dispersion relations of collective, intra-protein phonon-like excitations in these proteins for the first time. We found that the phonon energies show a marked softening and at the same time their population increases

  20. Cage occupancy and structural changes during hydrate formation from initial stages to resulting hydrate phase.

    PubMed

    Schicks, Judith M; Luzi-Helbing, Manja

    2013-11-01

    Hydrate formation processes and kinetics are still not sufficiently understood on a molecular level based on experimental data. In particular, the cavity formation and occupancy during the initial formation and growth processes of mixed gas hydrates are rarely investigated. In this study, we present the results of our time-depending Raman spectroscopic measurements during the formation of hydrates from ice and gases or gas mixtures such as CH4, CH4-CO2, CH4-H2S, CH4-C3H8, CH4-iso-C4H10, and CH4-neo-C5H12 at constant pressure and temperature conditions and constant composition of the feed gas phase. All investigated systems in this study show the incorporation of CH4 into the 5(12) cavities as first step in the initial stages of hydrate formation. Furthermore, the results imply that the initial hydrate phases differ from the resulting hydrate phase having reached a steady state regarding the occupancy and ratio of the small and large cavities of the hydrate.

  1. Time for the 70°C water precautionary option in the home dilution of powdered infant formula.

    PubMed

    Silano, Marco; Paganin, Paola; Davanzo, Riccardo

    2016-02-19

    Powdered infant formulas (PIF) are usually not sterile and may frequently be contaminated by several bacteria strains. Among them, Cronobacter species, previously known as Enterobacter sakazakii, is one of the most harmful, since it might be the causative agent of sepsis and meningitis in newborns and preterm infants during the first weeks of life. The mortality rate of these infections is up to 80 %. Therefore, some precautions are required in the home handling and dilution of PIF. Whereas there is wide consensus about the need that a PIF should be used immediately after being diluted or, if not, stored at < "5 °C", still recently the optimal temperature of the water used to dilute PIF is controversial among scientific societies and health agencies. The current knowledge is reviewed in this paper and provides sufficient evidence to cautiously advise the use of hot water at a temperature of "70 °C" in the dilution of PIF in order to prevent the Cronobacter sp. contamination and growth.

  2. Microscopic Origin of Strain Hardening in Methane Hydrate.

    PubMed

    Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi

    2016-03-24

    It has been reported for a long time that methane hydrate presents strain hardening, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain hardening only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain hardening under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-hardening phenomenon.

  3. [Raman spectroscopic investigation of hydrogen storage in nitrogen gas hydrates].

    PubMed

    Meng, Qing-guo; Liu, Chang-ling; Ye, Yu-guang; Li, Cheng-feng

    2012-08-01

    Recently, hydrogen storage using clathrate hydrate as a medium has become a hotspot of hydrogen storage research In the present paper, the laser Raman spectroscopy was used to study the hydrogen storage in nitrogen hydrate. The synthetic nitrogen hydrate was reacted with hydrogen gas under relatively mild conditions (e.g., 15 MPa, -18 degrees C). The Raman spectra of the reaction products show that the hydrogen molecules have enclathrated the cavities of the nitrogen hydrate, with multiple hydrogen cage occupancies in the clathrate cavities. The reaction time is an important factor affecting the hydrogen storage in nitrogen hydrate. The experimental results suggest that nitrogen hydrates are expected to be an effective media for hydrogen storage.

  4. Microscopic Origin of Strain Hardening in Methane Hydrate

    PubMed Central

    Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi

    2016-01-01

    It has been reported for a long time that methane hydrate presents strain hardening, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain hardening only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain hardening under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-hardening phenomenon. PMID:27009239

  5. Hydrate pingoes at Nyegga: some characteristic features

    NASA Astrophysics Data System (ADS)

    Hovland, M.

    2009-04-01

    Hydrate pingoes were observed on the seafloor during two different remotely operated vehicle (ROV)-dives, conducted by Statoil at complex-pockmark G11, at Nyegga, off Mid-Norway. Confirmation that these structures actually represent hydrate ice-cored sediment mounds (pingoes), was done by other investigators (Ivanov et al., 2006). Because it is expected that hydrate pingoes represent relatively dynamic seafloor topographic structures and that their shape and size most probably will change over relatively short time, it is important to know how to recognise them visually. Hovland and Svensen (2006) highlighted five different characteristic aspects that define hydrate pingoes on the sea floor: 1) They are dome- or disc-shaped features, which may attain any size from ~0.5 m in height and upwards. Inside pockmark G11, they were up to 1 m high. 2) They are circular or oval in plan view and may attain lateral sizes on the seafloor ranging upwards from ~0.5 m. Inside G11 they had lengths of several metres and widths of up to 4 m. 3) They have dense communities of organisms growing on their surfaces. At G11, they were overgrown with small pogonophoran tube-worms. 4) They have patches of white or grey bacterial mats growing on their surface, indicating advection (seepage) of reduced pore-waters. 5) They have small pits and patches of fluidized sediments on their surface, indicating pit corrosion of the sub-surface gas hydrate. Because gas hydrates often form in high-porosity, near-surface sediments, where water is readily available, it is thought that they will build up at locations where gases are actively migrating upwards from depth. However, gas hydrates are not stable in the presence of ambient seawater, as seawater is deficient in guest molecule gases (normally methane). Therefore, they tend to build up below surface above conduits for gas flow from depth. But, the near-surface hydrate ice-lenses will continually be corroded by seawater circulating into the sediments

  6. Energetic powder

    DOEpatents

    Jorgensen, Betty S.; Danen, Wayne C.

    2003-12-23

    Fluoroalkylsilane-coated metal particles. The particles have a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer. The particles may be prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.

  7. Ceramic Powders

    NASA Technical Reports Server (NTRS)

    1984-01-01

    In developing its product line of specialty ceramic powders and related products for government and industrial customers, including companies in the oil, automotive, electronics and nuclear industries, Advanced Refractory Technologies sought technical assistance from NERAC, Inc. in specific areas of ceramic materials and silicon technology, and for assistance in identifying possible applications of these materials in government programs and in the automotive and electronics industry. NERAC conducted a computerized search of several data bases and provided extensive information in the subject areas requested. NERAC's assistance resulted in transfer of technologies that helped ART staff develop a unique method for manufacture of ceramic materials to precise customer specifications.

  8. Umbilical cord care in premature infants: the effect of two different cord-care regimens (salicylic sugar powder vs chlorhexidine) on cord separation time and other outcomes.

    PubMed

    Pezzati, Marco; Rossi, Sauro; Tronchin, Michele; Dani, Carlo; Filippi, Luca; Rubaltelli, Firmino F

    2003-10-01

    To evaluate the effect of 2 cord-care regimens (salicylic sugar powder vs chlorhexidine as a 4% detergent water solution) on cord separation time and other outcomes in preterm infants. A prospective, randomized, controlled trial was conducted on 244 preterm newborns with a gestational age of <34 weeks and a birth weight of <2500 g. All preterm newborns were enrolled, regardless of their health condition. We excluded from the study infants whose conditions during the first hours of life required the catheterization of umbilical vessels. We also excluded from the general statistical analysis all newborns who had their programmed cord-care regimen changed because of the presence or the suspicion of omphalitis. On arrival at our neonatal intensive care unit or neonatal special care unit, infants were bathed thoroughly with a soap solution (Saugella, Guieu, Italy), and the umbilical cord (UC) was treated with 1 of the 2 antiseptic products chosen for the study. The stump was then folded and covered with common sterile, dry gauze and kept in place by an elastic net. Until cord detachment and at every diaper change, the cord stump was cleaned with sterile water and treated with the same product initially used for first-time cord care. On the third day of life, we obtained an umbilical swab either from the base of the cord or from the umbilicus if the cord was already sloughed. Six weeks after birth, during hospitalization or during a follow-up visit if already discharged, all infants had a medical examination to check the umbilicus area. Cord separation time, changing of the programmed cord-care regimen, death, omphalitis, sepsis, cord bleeding, nurses' opinion on treatments efficacy, and UC colonization were measured. The cord separation time was significantly lower in infants who were treated with salicylic sugar powder (6 +/- 2 days) than in infants who were treated with chlorhexidine (9 +/- 2 days). The programmed cord-care regimen was changed in a significantly

  9. Pore scale distribution of gas hydrates in sediments by micro X-ray Computed Tomography (X-CT)

    NASA Astrophysics Data System (ADS)

    Hu, G.; Li, C.; Ye, Y.; Liu, C.; Best, A. I.

    2013-12-01

    A dedicated apparatus was developed to observe in-situ pore scale distribution of gas hydrate directly during hydrate formation in artificial cores. The high-resolution X-ray Computed Tomography (type: GE Sensing & Inspection Technologies GmbH Phoenix x-ray V/tomex/s) was used and the effective resolution for observing gas hydrate bearing sediments can up to about 18μm. Methane gas hydrate was formed in 0.425-0.85mm sands under a pressure of 6MPa and a temperature of 3°C. During the process, CT scanning was conducted if there's a pressure drop (the scanning time is 66 minutes each time), so that the hydrate morphology could be detected. As a result, five scanning CT images of the same section during gas hydrate formation (i.e. hydrate saturation at 3.9%, 24.6%, 35.0%, 51.4% and 97.0%) were obtained. The result shows that at each hydrate saturation level, hydrate morphology models are complicated. The occurrence of 'floating model' (i.e. hydrate floats in pore fluid), 'contact model' (i.e. hydrate contact with the sediment particle), and the 'cementing model' (i.e. hydrates cement the sediment particles) can be found at the same time (Fig. 1). However, it shows that at different hydrate formation stages, the dominant hydrate morphology are not the same. For instance, at the first stage of hydrate formation, although there are some hydrates floating in the pore fluid, most hydrates connect the sediment particles. Consequently, the hydrate morphology at this moment can be described as a cementing model. With this method, it can be obtained that at the higher level of saturation (e.g., hydrate saturation at 24.6% and 35.0%), hydrates are mainly grow as a floating model. As hydrate saturation is much higher (e.g. after hydrate saturation is more than 51.4%), however, the floating hydrates coalesce with each other and the hydrates cement the sediment particle again. The direct observed hydrate morphology presented here may have significant impact on investigating

  10. Rock Physics Characterization of Porous Media Containing Hydrates Formed Out of Solution: Tetrathydrofuran VS. Dissolved Methane

    NASA Astrophysics Data System (ADS)

    Schicks, J. M.; Rydzy, M. B.; Spangenberg, E.; Batzle, M. L.

    2012-12-01

    Methane hydrate formation in sediments from the dissolved gas phase is a tedious and time-consuming task, due to the relatively low solubility of methane in water. A number of studies on physical properties of hydrated sediments have been conducted on sediments containing tetrahydrofuran (THF) hydrates instead. The use of THF as a hydrate former is convenient as it forms hydrate at atmospheric pressure and relatively high temperatures of about 277 K. It is completely miscible in water, thus forms hydrate out solution and promises homogeneous synthesis of THF hydrate in sediment. The applicability of THF as a proxy for methane hydrate formed out of solution, however, has often been questioned. To better understand whether THF hydrates represent a legitimate proxy for methane hydrates formed out of solution, ultrasonic velocity and resistivity measurements were performed on hydrated Ottawa Sand F110 sand and glass bead samples in conjunction with imaging techniques, such as micro X-ray computed tomography (MXCT), and scanning electron microscopy (SEM). Thereby the tests were conducted on samples containing hydrates formed both, from methane dissolved in water and with the use of THF. The results show, that in terms of ultrasonic velocities, THF and methane hydrates exhibit the same trend. As the hydrate crystallized in the pore space, no increase in velocity was observed until a critical hydrate saturation of 35-50 percent was exceeded. On the other hand, the bulk electrical resistivity increased with increasing gas hydrate saturation. Comparison with current rock physics models suggested that the gas hydrate formed out of solution in both cases exhibits pore-filling/ load-bearing behavior, i.e. it suggests that the hydrate is formed away from the grains. This was supported through the imaging. This series of measurements provided the first direct comparison of THF and methane hydrates formed out of solution in terms of how their distribution and location in the pore

  11. Micromechanical cohesion force measurements to determine cyclopentane hydrate interfacial properties.

    PubMed

    Aman, Zachary M; Joshi, Sanjeev E; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2012-06-15

    Hydrate aggregation and deposition are critical factors in determining where and when hydrates may plug a deepwater flowline. We present the first direct measurement of structure II (cyclopentane) hydrate cohesive forces in the water, liquid hydrocarbon and gas bulk phases. For fully annealed hydrate particles, gas phase cohesive forces were approximately twice that obtained in a liquid hydrocarbon phase, and approximately six times that obtained in the water phase. Direct measurements show that hydrate cohesion force in a water-continuous bulk may be only the product of solid-solid cohesion. When excess water was present on the hydrate surface, gas phase cohesive forces increased by a factor of three, suggesting the importance of the liquid or quasi-liquid layer (QLL) in determining cohesive force. Hydrate-steel adhesion force measurements show that, when the steel surface is coated with hydrophobic wax, forces decrease up to 96%. As the micromechanical force technique is uniquely capable of measuring hydrate-surface forces with variable contact time, the present work contains significant implications for hydrate applications in flow assurance.

  12. A rapid method for chemical fingerprint analysis of Pan Panax notoginseng powders by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    PubMed

    Liu, Peng; Yu, He-Shuil; Zhang, Li-Juan; Song, Xin-Bo; Kang, Li-Ping; Liu, Jing-Yuan; Zhang, Jie; Cao, Man; Yu, Kate; Kang, Ting-Guo; Ma, Bai-Ping

    2015-06-01

    A method coupling ultra-performance liquid chromatography (UPLC) with quadrupole time-of-flight mass spectrometer (Qtof MS) using the electrospray ionization (ESI) source was developed for the identification of the major saponins from Panax notoginseng powder (PNP). Ten different PNP samples were analyzed and evaluated for their quality by similarity evaluation and principle component analysis (PCA). Based on the accurate mass, summarized characteristic fragmentation behaviors, retention times of different types of saponins, related botanical biogenesis, and reported chromatographic behavior of saponins, fifty-one common peaks were effectively separated and identified, including 28 protopanaxadiol saponins and 18 protopanaxatriol saponins. Simultaneously, 15 significant discrepancy compounds were identified from the disqualified PNP samples. The established UPLC/Qtof MS fingerprint method was successfully applied for profiling and identifying the major saponins of PNP, providing a fast quality evaluation tool for distinguishing the authentic PNP and the adulterated products.

  13. Antifreezes act as catalysts for methane hydrate formation from ice.

    PubMed

    McLaurin, Graham; Shin, Kyuchul; Alavi, Saman; Ripmeester, John A

    2014-09-22

    Contrary to the thermodynamic inhibiting effect of methanol on methane hydrate formation from aqueous phases, hydrate forms quickly at high yield by exposing frozen water-methanol mixtures with methanol concentrations ranging from 0.6-10 wt% to methane gas at pressures from 125 bars at 253 K. Formation rates are some two orders of magnitude greater than those obtained for samples without methanol and conversion of ice is essentially complete. Ammonia has a similar catalytic effect when used in concentrations of 0.3-2.7 wt%. The structure I methane hydrate formed in this manner was characterized by powder X-ray diffraction and Raman spectroscopy. Steps in the possible mechanism of action of methanol were studied with molecular dynamics simulations of the Ih (0001) basal plane exposed to methanol and methane gas. Simulations show that methanol from a surface aqueous layer slowly migrates into the ice lattice. Methane gas is preferentially adsorbed into the aqueous methanol surface layer. Possible consequences of the catalytic methane hydrate formation on hydrate plug formation in gas pipelines, on large scale energy-efficient gas hydrate formation, and in planetary science are discussed.

  14. HYDRATE CORE DRILLING TESTS

    SciTech Connect

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

    2002-11-01

    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate formation comprised of coarse, large

  15. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems: DIFFUSION-DRIVEN HYDRATE GROWTH IN SANDS

    DOE PAGES

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; ...

    2017-02-01

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1 to 20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two- dimensional and basin-scalemore » three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. As a result, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.« less

  16. Pulsed neutron powder diffraction at high pressure by a capacity-increased sapphire anvil cell

    NASA Astrophysics Data System (ADS)

    Okuchi, Takuo; Yoshida, Masashi; Ohno, Yoshiki; Tomioka, Naotaka; Purevjav, Narangoo; Osakabe, Toyotaka; Harjo, Stefanus; Abe, Jun; Aizawa, Kazuya; Sasaki, Shigeo

    2013-12-01

    A new design of opposed anvil cell for time-of-flight neutron powder diffraction was prepared for use at advanced pulsed sources. A couple of single-crystal sapphire sphere anvils and a gasket of fully hardened Ti-Zr null alloy were combined to compress 35 mm3 of sample volume to 1 GPa and 11 mm3 to 2 GPa of pressures, respectively. A very high-quality powder diffraction pattern was obtained at Japan Proton Accelerator Research Complex for a controversial high pressure phase of methane hydrate. The counting statistics, resolution, absolute accuracy and d-value range of the pattern were all improved to be best suitable for precise structure refinement. The sample is optically accessible to be measured by Raman and fluorescence spectroscopy during and after compression. The current cell will be an alternative choice to study hydrogenous materials of complex structures that are stable at the described pressure regime.

  17. How Hydrate Saturation Anomalies are Diffusively Constructed and Advectively Smoothed

    NASA Astrophysics Data System (ADS)

    Rempel, A. W.; Irizarry, J. T.; VanderBeek, B. P.; Handwerger, A. L.

    2015-12-01

    The physical processes that control the bulk characteristics of hydrate reservoirs are captured reasonably well by long-established model formulations that are rooted in laboratory-verified phase equilibrium parameterizations and field-based estimates of in situ conditions. More detailed assessments of hydrate distribution, especially involving the occurrence of high-saturation hydrate anomalies have been more difficult to obtain. Spatial variations in sediment properties are of central importance for modifying the phase behavior and promoting focussed fluid flow. However, quantitative predictions of hydrate anomaly development cannot be made rigorously without also addressing the changes in phase behavior and mechanical balances that accompany changes in hydrate saturation level. We demonstrate how pore-scale geometrical controls on hydrate phase stability can be parameterized for incorporation in simulations of hydrate anomaly development along dipping coarse-grained layers embedded in a more fine-grained background that is less amenable to fluid transport. Model simulations demonstrate how hydrate anomaly growth along coarse-layer boundaries is promoted by diffusive gas transport from the adjacent fine-grained matrix, while advective transport favors more distributed growth within the coarse-grained material and so effectively limits the difference between saturation peaks and background levels. Further analysis demonstrates how sediment contacts are unloaded once hydrate saturation reaches sufficient levels to form a load-bearing skeleton that can evolve to produce segregated nodules and lenses. Decomposition of such growth forms poses a significant geohazard that is expected to be particularly sensitive to perturbations induced by gas extraction. The figure illustrates the predicted evolution of hydrate saturation Sh in a coarse-grained dipping layer showing how prominent bounding hydrate anomalies (spikes) supplied by diffusive gas transport at early times

  18. New Methods for Gas Hydrate Energy and Climate Studies

    NASA Astrophysics Data System (ADS)

    Ruppel, C. D.; Pohlman, J.; Waite, W. F.; Hunt, A. G.; Stern, L. A.; Casso, M.

    2015-12-01

    Over the past few years, the USGS Gas Hydrates Project has focused on advancements designed to enhance both energy resource and climate-hydrate interaction studies. On the energy side, the USGS now manages the Pressure Core Characterization Tools (PCCTs), which includes the Instrumented Pressure Testing Chamber (IPTC) that we have long maintained. These tools, originally built at Georgia Tech, are being used to analyze hydrate-bearing sediments recovered in pressure cores during gas hydrate drilling programs (e.g., Nankai 2012; India 2015). The USGS is now modifying the PCCTs for use on high-hydrate-saturation and sand-rich sediments and hopes to catalyze third-party tool development (e.g., visualization). The IPTC is also being used for experiments on sediments hosting synthetic methane hydrate, and our scanning electron microscope has recently been enhanced with a new cryo-stage for imaging hydrates. To support climate-hydrate interaction studies, the USGS has been re-assessing the amount of methane hydrate in permafrost-associated settings at high northern latitudes and examined the links between methane carbon emissions and gas hydrate dissociation. One approach relies on the noble gas signature of methane emissions. Hydrate dissociation uniquely releases noble gases partitioned by molecular weight, providing a potential fingerprint for hydrate-sourced methane emissions. In addition, we have linked a DOC analyzer with an IRMS at Woods Hole Oceanographic Institution, allowing rapid and precise measurement of DOC and DIC concentrations and carbon isotopic signatures. The USGS has also refined methods to measure real-time sea-air flux of methane and CO2 using cavity ring-down spectroscopy measurements coupled with other data. Acquiring ~8000 km of data on the Western Arctic, US Atlantic, and Svalbard margins, we have tested the Arctic methane catastrophe hypothesis and the link between seafloor methane emissions and sea-air methane flux.

  19. Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

    PubMed Central

    Firlar, Emre; Çınar, Simge; Kashyap, Sanjay; Akinc, Mufit; Prozorov, Tanya

    2015-01-01

    Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles. PMID:25996055

  20. Controls on Gas Hydrate Formation and Dissociation

    SciTech Connect

    Miriam Kastner; Ian MacDonald

    2006-03-03

    up-flow and down-flow of fluid at rates that range between 0.5 to 214 cm/yr and 2-162 cm/yr, respectively. The fluid flow system at the mound and background sites are coupled having opposite polarities that oscillate episodically between 14 days to {approx}4 months. Stability calculations suggest that despite bottom water temperature fluctuations, of up to {approx}3 C, the Bush Hill gas hydrate mound is presently stable, as also corroborated by the time-lapse video camera images that did not detect change in the gas hydrate mound. As long as methane (and other hydrocarbon) continues advecting at the observed rates the mound would remain stable. The {_}{sup 13}C-DIC data suggest that crude oil instead of methane serves as the primary electron-donor and metabolic substrate for anaerobic sulfate reduction. The oil-dominated environment at Bush Hill shields some of the methane bubbles from being oxidized both anaerobically in the sediment and aerobically in the water column. Consequently, the methane flux across the seafloor is higher at Bush hill than at non-oil rich seafloor gas hydrate regions, such as at Hydrate Ridge, Cascadia. The methane flux across the ocean/atmosphere interface is as well higher. Modeling the methane flux across this interface at three bubble plumes provides values that range from 180-2000 {_}mol/m{sup 2} day; extrapolating it over the Gulf of Mexico basin utilizing satellite data is in progress.

  1. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  2. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  3. [Hydration in clinical practice].

    PubMed

    Maristany, Cleofé Pérez-Portabella; Segurola Gurruchaga, Hegoi

    2011-01-01

    Water is an essential foundation for life, having both a regulatory and structural function. The former results from active and passive participation in all metabolic reactions, and its role in conserving and maintaining body temperature. Structurally speaking it is the major contributer to tissue mass, accounting for 60% of the basis of blood plasma, intracellular and intersticial fluid. Water is also part of the primary structures of life such as genetic material or proteins. Therefore, it is necessary that the nurse makes an early assessment of patients water needs to detect if there are signs of electrolyte imbalance. Dehydration can be a very serious problem, especially in children and the elderly. Dehydrations treatment with oral rehydration solution decreases the risk of developing hydration disorders, but even so, it is recommended to follow preventive measures to reduce the incidence and severity of dehydration. The key to having a proper hydration is prevention. Artificial nutrition encompasses the need for precise calculation of water needs in enteral nutrition as parenteral, so the nurse should be part of this process and use the tools for calculating the patient's requirements. All this helps to ensure an optimal nutritional status in patients at risk. Ethical dilemmas are becoming increasingly common in clinical practice. On the subject of artificial nutrition and hydration, there isn't yet any unanimous agreement regarding hydration as a basic care. It is necessary to take decisions in consensus with the health team, always thinking of the best interests of the patient.

  4. Hydration reactions of cement combinations containing vitrified incinerator fly ash

    SciTech Connect

    Dyer, Thomas D.; Dhir, Ravindra K

    2004-05-01

    One treatment option for municipal solid waste incinerator fly ash (IFA) is vitrification. The process yields a material containing reduced levels of trace metals relative to the original ash. The material is glassy and potentially suitable as a cement component in concrete. This paper examines the vitrification of an IFA and studies the hydration reactions of combinations of this vitrified material and Portland cement (PC). Isothermal conduction calorimetry, powder X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy were employed to study the hydration reactions. As the levels of vitrified ash increase, the quantities of AFt phase produced decrease, whilst quantities of AFm phase increase, due to the reduced levels of sulfate in the vitrified ash. The levels of calcium silicate hydrate (CSH) gel (inferred from estimates of quantities of gel-bound water) remain constant at 28 days regardless of vitrified ash content, indicating that the material is contributing toward the formation of this product.

  5. Scar management by means of occlusion and hydration: a comparative study of silicones versus a hydrating gel-cream.

    PubMed

    Hoeksema, Henk; De Vos, Marie; Verbelen, Jozef; Pirayesh, Ali; Monstrey, Stan

    2013-11-01

    Despite the worldwide use of silicones in scar management, its exact working mechanism based on a balanced occlusion and hydration, is still not completely elucidated. Moreover, it seems peculiar that silicones with completely different occlusive and hydrating properties still could provide a similar therapeutic effect. The objective of the first part of this study was to compare the occlusive and hydrating properties of three fluid silicone gels and a hydrating gel-cream. In a second part of the study these results were compared with those of silicone gel sheets. Tape stripped skin was used as a standardized scar like model on both forearms of 40 healthy volunteers. At specific times, trans epidermal water loss (TEWL) and the hydration state of the stratum corneum were measured and compared with intact skin and a scar-like control over a 3-4h period. Our study clearly demonstrated that fluid silicone gels and a hydrating gel-cream have comparable occlusive and hydrating properties while silicone gel sheets are much more occlusive, reducing TEWL values far below those of normal skin. A well-balanced, hydrating gel-cream can provide the same occlusive and hydrating properties as fluid silicone gels, suggesting that it could eventually replace silicones in scar treatment.

  6. The Methane Hydrate Reservoir System

    NASA Astrophysics Data System (ADS)

    Flemings, P. B.; Liu, X.

    2007-12-01

    We use multi phase flow modeling and field examples (Hydrate Ridge, offshore Oregon and Blake Ridge, offshore North Carolina) to demonstrate that the methane hydrate reservoir system links traditional and non- traditional hydrocarbon system components: free gas flow is a fundamental control on this system. As in a traditional hydrocarbon reservoir, gas migrates into the hydrate reservoir as a separate phase (secondary migration) where it is trapped in a gas column beneath the base of the hydrate layer. With sufficient gas supply, buoyancy forces exceed either the capillary entry pressure of the cap rock or the fracture strength of the cap rock, and gas leaks into the hydrate stability zone, or cap rock. When gas enters the hydrate stability zone and forms hydrate, it becomes a very non traditional reservoir. Free gas forms hydrate, depletes water, and elevates salinity until pore water is too saline for further hydrate formation: salinity and hydrate concentration increase upwards from the base of the regional hydrate stability zone (RHSZ) to the seafloor and the base of the hydrate stability zone has significant topography. Gas chimneys couple the free gas zone to the seafloor through high salinity conduits that are maintained at the three-phase boundary by gas flow. As a result, significant amounts of gaseous methane can bypass the RHSZ, which implies a significantly smaller hydrate reservoir than previously envisioned. Hydrate within gas chimneys lie at the three-phase boundary and thus small increases in temperature or decreases in pressure can immediately transport methane into the ocean. This type of hydrate deposit may be the most economical for producing energy because it has very high methane concentrations (Sh > 70%) located near the seafloor, which lie on the three-phase boundary.

  7. Molecular Dynamics Simulations of a Powder Model of the Intrinsically Disordered Protein Tau.

    PubMed

    Fichou, Yann; Heyden, Matthias; Zaccai, Giuseppe; Weik, Martin; Tobias, Douglas J

    2015-10-01

    The tau protein, whose aggregates are involved in Alzheimer's disease, is an intrinsically disordered protein (IDP) that regulates microtubule activity in neurons. An IDP lacks a single, well-defined structure and, rather, constantly exchanges among multiple conformations. In order to study IDP dynamics, the combination of experimental techniques, such as neutron scattering, and computational techniques, such as molecular dynamics (MD) simulations, is a powerful approach. Amorphous hydrated powder samples have been very useful for studying protein internal dynamics experimentally, e.g., using neutron scattering. Thus, there is demand for realistic in silico models of hydrated protein powders. Here we present an MD simulation analysis of a powder hydrated at 0.4 g water/g protein of the IDP tau in the temperature range 20-300 K. By comparing with neutron scattering data, we identify the protein-water interface as the predominant feature determining IDP dynamics. The so-called protein dynamical transition is shown to be attenuated, but not suppressed, in the parts of the protein that are not exposed to the solvent. In addition, we find similarities in the mean-squared displacements of the core of a globular protein and "dry" clusters formed by the IDP in hydrated powders. Thus, the ps to ns dynamics of proteins in hydrated powders originate mainly from those residues in contact with solvent. We propose that by measuring the dynamics of protein assemblies, such as aggregates, one might assess qualitatively their state of hydration.

  8. Powder treatment process

    DOEpatents

    Weyand, John D.

    1988-01-01

    (1) A process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder.

  9. Powder treatment process

    DOEpatents

    Weyand, J.D.

    1988-02-09

    Disclosed are: (1) a process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder. 2 figs.

  10. Natural gas hydrates on the North Slope of Alaska

    SciTech Connect

    Collett, T.S.

    1991-01-01

    Gas hydrates are crystalline substances composed of water and gas, mainly methane, in which a solid-water lattice accommodates gas molecules in a cage-like structure, or clathrate. These substances often have been regarded as a potential (unconventional) source of natural gas. Significant quantities of naturally occurring gas hydrates have been detected in many regions of the Arctic including Siberia, the Mackenzie River Delta, and the North Slope of Alaska. On the North Slope, the methane-hydrate stability zone is areally extensive beneath most of the coastal plain province and has thicknesses as great as 1000 meters in the Prudhoe Bay area. Gas hydrates have been identified in 50 exploratory and production wells using well-log responses calibrated to the response of an interval in one well where gas hydrates were recovered in a core by ARCO Alaska and EXXON. Most of these gas hydrates occur in six laterally continuous Upper Cretaceous and lower Tertiary sandstone and conglomerate units; all these gas hydrates are geographically restricted to the area overlying the eastern part of the Kuparuk River Oil Field and the western part of the Prudhoe Bay Oil Field. The volume of gas within these gas hydrates is estimated to be about 1.0 {times} 10{sup 12} to 1.2 {times} 10{sup 12} cubic meters (37 to 44 trillion cubic feet), or about twice the volume of conventional gas in the Prudhoe Bay Field. Geochemical analyses of well samples suggest that the identified hydrates probably contain a mixture of deep-source thermogenic gas and shallow microbial gas that was either directly converted to gas hydrate or first concentrated in existing traps and later converted to gas hydrate. The thermogenic gas probably migrated from deeper reservoirs along the same faults thought to be migration pathways for the large volumes of shallow, heavy oil that occur in this area. 51 refs., 11 figs., 3 tabs.

  11. Water Dynamics in the Hydration Shells of Biomolecules.

    PubMed

    Laage, Damien; Elsaesser, Thomas; Hynes, James T

    2017-03-01

    The structure and function of biomolecules are strongly influenced by their hydration shells. Structural fluctuations and molecular excitations of hydrating water molecules cover a broad range in space and time, from individual water molecules to larger pools and from femtosecond to microsecond time scales. Recent progress in theory and molecular dynamics simulations as well as in ultrafast vibrational spectroscopy has led to new and detailed insight into fluctuations of water structure, elementary water motions, electric fields at hydrated biointerfaces, and processes of vibrational relaxation and energy dissipation. Here, we review recent advances in both theory and experiment, focusing on hydrated DNA, proteins, and phospholipids, and compare dynamics in the hydration shells to bulk water.

  12. Water Dynamics in the Hydration Shells of Biomolecules

    PubMed Central

    2017-01-01

    The structure and function of biomolecules are strongly influenced by their hydration shells. Structural fluctuations and molecular excitations of hydrating water molecules cover a broad range in space and time, from individual water molecules to larger pools and from femtosecond to microsecond time scales. Recent progress in theory and molecular dynamics simulations as well as in ultrafast vibrational spectroscopy has led to new and detailed insight into fluctuations of water structure, elementary water motions, electric fields at hydrated biointerfaces, and processes of vibrational relaxation and energy dissipation. Here, we review recent advances in both theory and experiment, focusing on hydrated DNA, proteins, and phospholipids, and compare dynamics in the hydration shells to bulk water. PMID:28248491

  13. Drilling program investigates permafrost gas hydrates

    NASA Astrophysics Data System (ADS)

    Dallimore, Scott R.; Collett, Timothy S.; Weber, Michael; Uchida, Takahashi

    On 25 December 2001, fieldwork began on a new gas hydrate research well program at the northeastern edge of the Mackenzie Delta, Northwest Territories, Canada (Figure 1, top). The Mallik research well program of 2001-2002 will drill a 1200-m deep main production research well, and, for the first time, two 1150-m-deep scientific observation wells offset 40 m from the main well (Figure 1, bottom) for geophysical monitoring of the main well. The science and engineering objectives are to assess the production properties of gas hydrates and determine the stability of continental gas hydrates both in terms of past climate warming events and in response to warming trends predicted by various climate change models.

  14. Fortification of instant coffee beverages - influence of functional ingredients, packaging material and storage time on physical properties of newly formulated, enriched instant coffee powders.

    PubMed

    Benković, Maja; Srečec, Siniša; Špoljarić, Igor; Mršić, Gordan; Bauman, Ingrid

    2015-10-01

    Consumer demands for healthy, functional foods are growing rapidly nowadays. Coffee, as one of the most widespread commodities, represents an interesting aspect for enrichment, since it is consumed by millions of people on a daily basis. The aim of this study was to formulate enriched instant coffee powders with the purpose of estimating the influence of storage time, functional ingredients and packaging material on physical and sensory properties of the mixtures. Storage time of 6 months significantly (P <0.05) influenced moisture content of the mixtures, which rose linearly with an increase in storage time. Packaging material proved to be an important variable affecting moisture content, particle size, colour and cohesion index. Functional ingredients (vitamins A and C, iron, inulin and oligofructose) influenced particle size, dispersibility, wettability and, in terms of sensory analysis, grades for aftertaste, chemical taste and overall acceptability. Addition of functional ingredients significantly influenced some particle size distribution parameters and reconstitution properties, causing an increase in wettability and dispersibility times. Furthermore, in sensory terms, it influenced aftertaste and chemical taste grades. Packaging material significantly influenced moisture content, some particle size distribution parameters, colour and cohesion index. © 2014 Society of Chemical Industry.

  15. Characterization of cromolyn sodium hydrates and its formulation by (23) Na-multiquantum and magic-angle spinning nuclear magnetic resonance spectroscopy.

    PubMed

    Umino, Makoto; Higashi, Kenjirou; Masu, Hyuma; Limwikrant, Waree; Yamamoto, Keiji; Moribe, Kunikazu

    2013-08-01

    We characterized cromolyn sodium (CS) hydrates and evaluated their molecular states in low-dose formulations using Na-multiquantum magic-angle spinning (MQMAS) nuclear magnetic resonance (NMR) analysis. Two CS hydrates, low-water-content hydrated form and high-water-content hydrated form containing 2-3 and 5-6 hydrates, respectively, were prepared by humidification. Single-crystal X-ray diffraction and powder X-ray diffraction analysis revealed that these CS hydrates contained sodium channel structures and that water molecules were adsorbed on the sodium nucleus. (13) C-cross-polarization/MAS NMR spectra of these hydrates revealed similar results, confirming that the water molecules were adsorbed not on the cromolyn skeletons but mainly on the sodium nucleus. In contrast, (23) Na-MQMAS NMR analysis allowed us to clearly distinguish these hydrates without discernible effects from quadrupolar interaction. Thus, MQMAS NMR analysis is a valuable tool for evaluating salt drugs and their formulations.

  16. Calorimetric studies of the kinetic unfreezing of molecular motions in hydrated lysozyme, hemoglobin, and myoglobin.

    PubMed Central

    Sartor, G; Mayer, E; Johari, G P

    1994-01-01

    Differential scanning calorimetric (DSC) studies of the glassy states of as-received and hydrated lysozyme, hemoglobin, and myoglobin powders, with water contents of < or = 0.25, < or = 0.30, and < or = 0.29 g/g of protein, show that their heat capacity slowly increases with increasing temperature, without showing an abrupt increase characteristic of glass-->liquid transition. Annealing (also referred to as physical aging) of the hydrated proteins causes their DSC scans to show an endothermic region, similar to an overshoot, immediately above the annealing temperature. This annealing effect appears at all temperatures between approximately 150 and 300 K. The area under these peaks increases with increasing annealing time at a fixed temperature. The effects are attributed to the presence of a large number of local structures in which macromolecular segments diffuse at different time scales over a broad range. The lowest time scale corresponds to the > N-H and -O-H group motions which become kinetically unfrozen at approximately 150-170 K on heating at a rate of 30 K min-1 and which have a relaxation time of 5-10 s in this temperature range. The annealing effects confirm that the individual glass transition of the relaxing local regions is spread over a temperature range up to the denaturation temperature region of the proteins. The interpretation is supported by simulation of DSC scans in which the distribution of relaxation times is assumed to be exceptionally broad and in which annealing done at several temperatures over a wide range produces endothermic effects (or regions of DSC scans) qualitatively similar to those observed for the hydrated proteins. PMID:8130342

  17. Diffusion of Hydration Water around Intrinsically Disordered Proteins.

    PubMed

    Rani, Pooja; Biswas, Parbati

    2015-10-22

    Hydration water dynamics around globular proteins have attracted considerable attention in the past decades. This work investigates the hydration water dynamics around partially/fully intrinsically disordered proteins and compares it to that of the globular proteins via molecular dynamics simulations. The translational diffusion of the hydration water is examined by evaluating the mean-square displacement and the velocity autocorrelation function, while the rotational diffusion is probed through the dipole-dipole time correlation function. The results reveal that the translational and rotational motions of water molecules at the surface of intrinsically disordered proteins/regions are less restricted as compared to those around globular proteins/ordered regions, which is reflected in their higher diffusion coefficient and lower orientational relaxation time. The restricted mobility of hydration water in the vicinity of the protein leads to a sublinear diffusion in a heterogeneous interface. A positive correlation between the mean number of hydrogen bonds and the diffusion coefficient of hydration water implies higher mobility of water molecules at the surface of disordered proteins, which is due to their higher number of hydrogen bonds. Enhanced hydration water mobility around disordered proteins/regions is also related to their higher hydration capacity, low hydrophobicity, and increased internal protein motions. Thus, we generalize that the intrinsically disordered proteins/regions are associated with higher hydration water mobility as compared to globular protein/ordered regions, which may help to elucidate their varied functional specificity.

  18. Hydration dynamics of the collagen triple helix by NMR.

    PubMed

    Melacini, G; Bonvin, A M; Goodman, M; Boelens, R; Kaptein, R

    2000-07-28

    The hydration of the collagen-like Ac-(Gly-Pro-Hyp)(6)-NH(2) triple-helical peptide in solution was investigated using an integrated set of high-resolution NMR hydration experiments, including different recently developed exchange-network editing methods. This approach was designed to explore the hydration dynamics in the proximity of labile groups, such as the hydroxyproline hydroxyl group, and revealed that the first shell of hydration in collagen-like triple helices is kinetically labile with upper limits for water molecule residence times in the nanosecond to sub-nanosecond range. This result is consistent with a "hopping" hydration model in which solvent molecules are exchanged in and out of solvation sites at a rate that is not directly correlated to the degree of site localization. The hopping model thus reconciles the dynamic view of hydration revealed by NMR with the previously suggested partially ordered semi-clathrate-like cylinder of hydration. In addition, the nanosecond to sub-nanosecond upper limits for water molecule residence times imply that hydration-dehydration events are not likely to be the rate-limiting step for triple helix self-recognition, complementing previous investigations on water dynamics in collagen fibers. This study has also revealed labile proton features expected to facilitate the characterization of the structure and folding of triple helices in collagen peptides.

  19. Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Stern, L.A.; Lorenson, T.D.; Pinkston, J.C.

    2011-01-01

    Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5. m to 760.1. m depth, and sections investigated here were retrieved from 619.9. m and 661.0. m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70-75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20-120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas. ?? 2009.

  20. Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Stern, Laura A.; Lorenson, T.D.; Pinkston, John C.

    2011-01-01

    Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA–DOE–USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5 m to 760.1 m depth, and sections investigated here were retrieved from 619.9 m and 661.0 m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70–75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20–120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas.

  1. Pilot scale experiments of magnesia hydration under gas-liquid-solid (three-phase) reaction system

    NASA Astrophysics Data System (ADS)

    Tang, Xiaojia; Lv, Qiwei; Yin, Lin; Nie, Yixing; Jin, Qi; Ji, Yangyuan; Zhu, Yimin

    2017-08-01

    Pilot scale experiments were conducted to prepare magnesium hydroxide by magnesia hydration under gas-liquid-solid (three-phase) reaction system. The effect of reaction pressure, reactivity and particle size of magnesia and the concentration of the pulp on the degree of hydration was investigated. The results indicated that the hydration reaction occurred at the first 30min mainly. During the set reaction condition, degree of hydration of 68% could be obtained at the reaction pressure of 0.2MPa, concentration of pulp of 5%w/w with high reactivity and fine powder. The promotion effect on the degree of hydration caused by the three-phase reaction system was mostly attributed to the exfoliation of steam.

  2. Detailed analysis of methane hydrate concentrated zone of lobe type

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Saeki, T.; Inamori, T.; Fujii, T.; Shimoda, N.

    2007-12-01

    Japan Oil, Gas and Metals National Corporation (hereinafter called JOGMEC), as a member of MH21 Research Consortium, takes charge of a study of the Research for Resources Assessment, and is pursuing a possibility that methane hydrate, which is presumed to be distributed around ocean area of Japan, will be energy resources. JOGMEC is currently conducting analysis of seismic data which was acquired by 3D seismic survey conducted from Tokai-Oki to Kumano-nada in the eastern Nankai Trough by METI (Ministry of Economy, Trade and Industry) in 2002 under the national program of assessment for methane hydrates as energy resources. It was understood that methane hydrate was correlated to high resistivity and high velocity based on the results of drilling surveys and velocity analysis, and that methane hydrate concentrated zones can be roughly classified into the channels and lobes in seismic geomorphology because they were characterized with reserves consisting turbidite sand bodies. In this study, the detailed analysis of the inner structure of the methane hydrate concentrated zone of lobe type was conducted to understand the occurrence configurations of methane hydrates. The reflected waves that construct the methane hydrate concentrated zones in the seismic data were extracted and those reflected waves were classified into some groups every one reflector. As the result, some reflectors that construct the methane hydrate concentrated zones were revealed. Those reflectors show the layers including methane hydrates, and the detailed distribution of the methane hydrates in those layers was revealed by the intensity distribution of the amplitude. This time, we introduce the example of the detailed analysis of the methane hydrate concentrated zone in the lobe of submarine fan.

  3. Selective Encaging of N2O in N2O-N2 Binary Gas Hydrates via Hydrate-Based Gas Separation.

    PubMed

    Yang, Youjeong; Shin, Donghoon; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Kim, Dongseon; Shin, Hee-Young; Cha, Minjun; Yoon, Ji-Ho

    2017-02-22

    The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N2O-N2) binary gas hydrates formed from N2O/N2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N2O-N2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for N2O-N2 binary gas hydrate formed from N2O/N2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N2O molecules occupy both large and small cages of the sI hydrate. In contrast, there is a single Raman band of N2O molecules for N2O-N2 binary gas hydrate formed from N2O/N2 (20/80 mol %) gas mixture, indicating that N2O molecules are trapped in only large cages of sI hydrate. From temperature-dependent Raman spectra and the Predictive Soave-Redlich-Kwong (PSRK) model calculation, we confirm the self-preservation of N2O-N2 binary gas hydrates in the temperature range of 210-270 K. Both the experimental measurements and the PSRK model calculations demonstrate the preferential occupation of N2O molecules rather than N2 molecules in the hydrate cages, leading to a possible process for separating N2O from gas mixtures via hydrate formation. The phase equilibrium conditions, pseudo pressure-composition (P-x) diagram, and gas storage capacity of N2O-N2 binary gas hydrates are discussed in detail.

  4. Evaluation of a rapid hydration protocol: Safety and effectiveness.

    PubMed

    Meredith, Sean; Hilliard, Jane; Vaillancourt, Regis

    2017-06-01

    Background The Children's Hospital of Eastern Ontario (CHEO) has implemented a rapid hydration protocol that may reduce the time required to achieve urine specific gravity and pH targets prior to chemotherapy. Objective The aim of this study was to determine if a rapid hydration protocol resulted in a shorter time to chemotherapy administration and during peak staffing levels without increasing adverse effects. Methods A retrospective chart review was conducted using data from electronic and paper medical charts, the hematology/oncology whiteboard, and video recordings. Patients who received cyclophosphamide, methotrexate, cisplatin and ifosfamide during the study period were included in the chart review. A urine specific gravity of ≤1.01, and in most cases a urine pH ≥7 was required to begin chemotherapy. Differences in time parameters between the standard and rapid hydration protocols were measured. Comparable parameters included the time from the start of pre-chemotherapy hydration to meeting urine targets, time from starting hydration to administration of chemotherapy, length of hospital stay and the number of chemotherapy administrations that were initiated prior to the nursing shift change at 19:30 h. Results Data were collected from 116 pre-chemotherapy intravenous hydration events administered to 25 different patients. There was a shorter time required to reach urine specific gravity and pH targets with the rapid hydration protocol compared to the standard hydration protocol, which translated into initiating chemotherapy sooner. There was also a shorter overall length of hospital stay and administration of chemotherapy occurred before the nursing shift change more often in the rapid hydration cohort compared to those patients who received the standard hydration protocol. There were no significant differences in adverse effects between the groups. Conclusion Patients receiving rapid hydration had a shorter time to chemotherapy administration and had a

  5. The Hydrated Electron

    NASA Astrophysics Data System (ADS)

    Herbert, John M.; Coons, Marc P.

    2017-05-01

    Existence of a hydrated electron as a byproduct of water radiolysis was established more than 50 years ago, yet this species continues to attract significant attention due to its role in radiation chemistry, including DNA damage, and because questions persist regarding its detailed structure. This work provides an overview of what is known in regards to the structure and spectroscopy of the hydrated electron, both in liquid water and in clusters [Formula: see text], the latter of which provide model systems for how water networks accommodate an excess electron. In clusters, the existence of both surface-bound and internally bound states of the excess electron has elicited much debate, whereas in bulk water there are questions regarding how best to understand the structure of the excess electron's spin density. The energetics of the equilibrium species e-(aq) and its excited states, in bulk water and at the air/water interface, are also addressed.

  6. Hydration of cyanin dyes

    NASA Astrophysics Data System (ADS)

    Calzolari, Arrigo; Monti, Susanna; Ruini, Alice; Catellani, Alessandra

    2010-03-01

    We investigated the hydration properties of the cyanin dye molecule in the ionic flavylium configuration, through massive classical (force field) and ab initio (Car-Parrinello) molecular dynamics simulations at room temperature. Classical and quantum mechanical results coherently describe the structure of the first solvation shell. We discuss the hydrophobicity/hydrophilicity of the molecule in terms of attractive lateral hydroxyl-water and repulsive carbon π-water interactions. The analysis of the electronic structure shows a net polarization and a molecular orbital redistribution induced by the polar solvent on the intrinsic (gas phase) properties of the dye. Changing the properties of the molecule, the hydration effects should be carefully taken into account in the further interactions of cyanin with the external environment.

  7. Hydration of mechanically activated granulated blast furnace slag

    NASA Astrophysics Data System (ADS)

    Kumar, Rakesh; Kumar, Sanjay; Badjena, S.; Mehrotra, S. P.

    2005-12-01

    Ground granulated blast furnace slag (GGBFS) is known to possess latent hydraulic activity, i.e., it shows cementitious properties when in contact with water over a long period of time. Results are presented in this article to show that, in sharp contrast to published literature on the hydration of neat GGBFS, the complete hydration of slag is possible in a short time (days), even without a chemical activator. This is achieved if the slag used for hydration is mechanically activated, using an attrition mill. The nature of the hydration product of the mechanically activated slag depends not only on the initial specific surface area (SSA) of the slag but also on the surface activation, as manifested by the change in the zeta potential ( ξ) of the slag during the milling process. Depending upon the SSA and the ξ, the hydration product changed from nonreacted slag with high porosity (slag SSA < 0.3 m2/g, ξ>-29 mV) to hydrated slag with a compact structure (SSA=0.3 to 0.4 m2/g, ξ=-29 to -31 mV), and, finally, to fully hydrated slag with high porosity (SSA>0.4 m2/g, ξ ˜ 26 mV). Unlike the poorly crystalline hydration product formed by the nonactivated slag, even after prolonged hydration for years, the hydration product of mechanically activated slag was crystalline in nature. The crystallinity of the product improved as the duration of the mechanical activation increased. The calcium-silicate-hydrate (C-S-H) phases present in the slag hydration product, characterized by a Ca/Si ratio of 0.7 to 1.5, were similar to those found for the hydraulic cement binder, except for the presence of Mg and Al as impurities. In addition, the presence of a di-calcium-silicate-hydrate phase ( α-C2SH), which normally forms under hydrothermal conditions, and a Ca-deficient and Si-Al-rich phase (average Ca/Si mole ratio < 0.1 and Si/Al ˜ 3) is indicated, especially in the hydration product of slag that was activated for a longer time.

  8. Hydration dependence of myoglobin dynamics studied with elastic neutron scattering, differential scanning calorimetry and broadband dielectric spectroscopy.

    PubMed

    Fomina, Margarita; Schirò, Giorgio; Cupane, Antonio

    2014-01-01

    In this work we present a thorough investigation of the hydration dependence of myoglobin dynamics. The study is performed on D2O-hydrated protein powders in the hydration range 0hydration water system are investigated with Broadband Dielectric Spectroscopy; finally, Differential Scanning Calorimetry is used to obtain a thermodynamic description of the system. The effect of increasing hydration is to speed up the relaxations of the myoglobin+hydration water system and, thermodynamically, to decrease the glass transition temperature; these effects tend to saturate at h values greater than ~0.3. Moreover, the calorimetric scans put in evidence the occurrence of an endothermic peak whose onset temperature is located at ~230K independent of hydration. From the point of view of the protein equilibrium fluctuations, while the amplitude of anharmonic mean square displacements is found to increase with hydration, their onset temperature (i.e. the onset temperature of the well known "protein dynamical transition") is hydration independent. On the basis of the above results, the relevance of protein+hydration water relaxations and of the thermodynamic state of hydration water to the onset of the protein dynamical transition is discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Arctic Gas hydrate, Environment and Climate

    NASA Astrophysics Data System (ADS)

    Mienert, Jurgen; Andreassen, Karin; Bünz, Stefan; Carroll, JoLynn; Ferre, Benedicte; Knies, Jochen; Panieri, Giuliana; Rasmussen, Tine; Myhre, Cathrine Lund

    2015-04-01

    Arctic methane hydrate exists on land beneath permafrost regions and offshore in shelf and continental margins sediments. Methane or gas hydrate, an ice-like substrate, consists mainly of light hydrocarbons (mostly methane from biogenic sources but also ethane and propane from thermogenic sources) entrapped by a rigid cage of water molecules. The pressure created by the overlying water and sediments offshore stabilizes the CH4 in continental margins at a temperature range well above freezing point; consequently CH4 exists as methane ice beneath the seabed. Though the accurate volume of Arctic methane hydrate and thus the methane stored in hydrates throughout the Quaternary is still unknown it must be enormous if one considers the vast regions of Arctic continental shelves and margins as well as permafrost areas offshore and on land. Today's subseabed methane hydrate reservoirs are the remnants from the last ice age and remain elusive targets for both unconventional energy and as a natural methane emitter influencing ocean environments and ecosystems. It is still contentious at what rate Arctic warming may govern hydrate melting, and whether the methane ascending from the ocean floor through the hydrosphere reaches the atmosphere. As indicated by Greenland ice core records, the atmospheric methane concentration rose rapidly from ca. 500 ppb to ca. 750 ppb over a short time period of just 150 years at the termination of the younger Dryas period ca. 11600 years ago, but the dissociation of large quantities of methane hydrates on the ocean floor have not been documented yet (Brook et al., 2014 and references within). But with the major projected warming and sea ice melting trend (Knies et al., 2014) one may ask, for how long will CH4 stay trapped in methane hydrates if surface and deep-ocean water masses will warm and permafrost continuous to melt (Portnov et al. 2014). How much of the Arctic methane will be consumed by the micro- and macrofauna, how much will

  10. Experimental Study of Gas Hydrate Dynamics

    NASA Astrophysics Data System (ADS)

    Fandino, O.; Ruffine, L.

    2011-12-01

    Important quantities of methane and other gases are trapped below the seafloor and in the permafrost by an ice-like solid, called gas hydrates or clathrate hydrates. The latter is formed when water is mixing with different gases at high pressures and low temperatures. Due to a their possible use as a source of energy [1] or the problematic related to flow assurance failure in pipelines [2] the understanding of their processes of formation/destabilisation of these structures becomes a goal for many laboratories research as well as industries. In this work we present an experimental study on the stochastic behaviour of hydrate formation from a bulk phase. The method used here for the experiments was to repeat several time the same hydrate formation procedure and to notice the different from one experiment to another. A variable-volume type high-pressure apparatus with two sapphire windows was used. This device, already presented by Ruffine et al.[3], allows us to perform both kinetics and phase equilibrium measurements. Three initial pressure conditions were considered here, 5.0 MPa, 7.5 MPa and 10.0 MPa. Hydrates have been formed, then allowed to dissociate by stepwise heating. The memory effect has also been investigated after complete dissociation. It turned out that, although the thermodynamics conditions of formation and/or destabilization were reproducible. An attempt to determine the influence of pressure on the nucleation induction time will be discussed. References 1. Sum, A. K.; Koh, C. A.; Sloan, E. D., Clathrate Hydrates: From Laboratory Science to Engineering Practice. Industrial & Engineering Chemistry Research 2009, 48, 7457-7465. 2. Sloan, E. D., A changing hydrate paradigm-from apprehension to avoidance to risk management. Fluid Phase Equilibria 2005, 228, 67-74. 3. Ruffine, L.; Donval, J. P.; Charlou, J. L.; Cremière, A.; Zehnder, B. H., Experimental study of gas hydrate formation and destabilisation using a novel high-pressure apparatus. Marine

  11. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

    DOE PAGES

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; ...

    2017-02-07

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1 to 20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two- dimensional and basin-scalemore » three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. As a result, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.« less

  12. Structural stability of methane hydrate at high pressures

    USGS Publications Warehouse

    Shu, J.; Chen, X.; Chou, I.-Ming; Yang, W.; Hu, Jiawen; Hemley, R.J.; Mao, Ho-kwang

    2011-01-01

    The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil cells. The diffraction data for types II (sII) and H (sH) were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sI methane hydrate transforms to the sII phase at 120 MPa, and then to the sH phase at 600 MPa. The sII methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII (Pn3m). The results highlight the role of guest (CH4)-host (H2O) interactions in the stabilization of the hydrate structures under pressure. ?? 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

  13. Oxidation and hydration of U3O8 materials following controlled exposure to temperature and humidity.

    PubMed

    Tamasi, Alison L; Boland, Kevin S; Czerwinski, Kenneth; Ellis, Jason K; Kozimor, Stosh A; Martin, Richard L; Pugmire, Alison L; Reilly, Dallas; Scott, Brian L; Sutton, Andrew D; Wagner, Gregory L; Walensky, Justin R; Wilkerson, Marianne P

    2015-04-21

    Chemical signatures correlated with uranium oxide processing are of interest to forensic science for inferring sample provenance. Identification of temporal changes in chemical structures of process uranium materials as a function of controlled temperatures and relative humidities may provide additional information regarding sample history. In this study, a high-purity α-U3O8 sample and three other uranium oxide samples synthesized from reaction routes used in nuclear conversion processes were stored under controlled conditions over 2-3.5 years, and powder X-ray diffraction analysis and X-ray absorption spectroscopy were employed to characterize chemical speciation. Signatures measured from the α-U3O8 sample indicated that the material oxidized and hydrated after storage under high humidity conditions over time. Impurities, such as uranyl fluoride or schoepites, were initially detectable in the other uranium oxide samples. After storage under controlled conditions, the analyses of the samples revealed oxidation over time, although the signature of the uranyl fluoride impurity diminished. The presence of schoepite phases in older uranium oxide material is likely indicative of storage under high humidity and should be taken into account for assessing sample history. The absence of a signature from a chemical impurity, such as uranyl fluoride hydrate, in an older material may not preclude its presence at the initial time of production. LA-UR-15-21495.

  14. Oxidation and Hydration of U 3 O 8 Materials Following Controlled Exposure to Temperature and Humidity

    DOE PAGES

    Tamasi, Alison L.; Boland, Kevin S.; Czerwinski, Kenneth; ...

    2015-03-18

    Chemical signatures correlated with uranium oxide processing are of interest to forensic science for inferring sample provenance. Identification of temporal changes in chemical structures of process uranium materials as a function of controlled temperatures and relative humidities may provide additional information regarding sample history. In our study, a high-purity α-U3O8 sample and three other uranium oxide samples synthesized from reaction routes used in nuclear conversion processes were stored under controlled conditions over 2–3.5 years, and powder X-ray diffraction analysis and X-ray absorption spectroscopy were employed to characterize chemical speciation. We measured signatures from the α-U3O8 sample indicated that the materialmore » oxidized and hydrated after storage under high humidity conditions over time. Impurities, such as uranyl fluoride or schoepites, were initially detectable in the other uranium oxide samples. After storage under controlled conditions, the analyses of the samples revealed oxidation over time, although the signature of the uranyl fluoride impurity diminished. The presence of schoepite phases in older uranium oxide material is likely indicative of storage under high humidity and should be taken into account for assessing sample history. Finally, the absence of a signature from a chemical impurity, such as uranyl fluoride hydrate, in an older material may not preclude its presence at the initial time of production. LA-UR-15-21495.« less

  15. Methane Clathrate Hydrate Prospecting

    NASA Technical Reports Server (NTRS)

    Duxbury, N.; Romanovsky, V.

    2003-01-01

    A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas hydrate (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-hydrate sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas hydrate, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.

  16. Hydration dynamics near a model protein surface

    SciTech Connect

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    The evolution of water dynamics from dilute to very high concentration solutions of a prototypical hydrophobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering and molecular dynamics simulation for both the completely deuterated and completely hydrogenated leucine monomer. We observe several unexpected features in the dynamics of these biological solutions under ambient conditions. The NALMA dynamics shows evidence of de Gennes narrowing, an indication of coherent long timescale structural relaxation dynamics. The translational water dynamics are analyzed in a first approximation with a jump diffusion model. At the highest solute concentrations, the hydration water dynamics is significantly suppressed and characterized by a long residential time and a slow diffusion coefficient. The analysis of the more dilute concentration solutions takes into account the results of the 2.0M solution as a model of the first hydration shell. Subtracting the first hydration layer based on the 2.0M spectra, the translational diffusion dynamics is still suppressed, although the rotational relaxation time and residential time are converged to bulk-water values. Molecular dynamics analysis shows spatially heterogeneous dynamics at high concentration that becomes homogeneous at more dilute concentrations. We discuss the hydration dynamics results of this model protein system in the context of glassy systems, protein function, and protein-protein interfaces.

  17. Hydration of Portland cement with additions of calcium sulfoaluminates

    SciTech Connect

    Le Saout, Gwenn; Lothenbach, Barbara; Hori, Akihiro; Higuchi, Takayuki; Winnefeld, Frank

    2013-01-15

    The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

  18. The effect of beam size on real-time determination of powder blend homogeneity by an online near infrared sensor.

    PubMed

    Li, Weiyong; Johnson, Mark C; Bruce, Rick; Rasmussen, Henrik; Worosila, Gregory D

    2007-01-17

    Online blend uniformity study was conducted with a near infrared (NIR) sensor and a simulated formulation consisting of acetaminophen and four excipients. Quantitative calibration models were developed and validated for the sensor and assay results were obtained in real time for acetaminophen and three excipients. Mechanical thief samples were also collected during the study. The samples were analyzed offline by a bench-top near infrared spectrometer and used as reference. Comparison of the online and offline data shows a significant difference in standard deviation for acetaminophen and excipients. R.S.D. data calculated from the real-time assay values for acetaminophen was 3.5-13.2-fold lower than those from the offline results. The cause for the discrepancy is believed to be the large beam size of the online sensor. A simple complete-random-mixture model was used to explain the discrepancy. It is concluded that beam size is an important factor in quantitative online blending uniformity studies.

  19. Dynamics of the gas hydrate system off Svalbard

    NASA Astrophysics Data System (ADS)

    Berndt, Christian; Feseker, Tomas; Treude, Tina; Krastel, Sebastian; Liebetrau, Volker; Niemann, Helge; Bertics, Victoria; Dumke, Ines; Dünnbier, Karolin; Ferre, Benedicte; Graves, Carolyn; Gross, Felix; Hissmann, Karen; Hühnerbach, Veit; Krause, Stefan; Lieser, Kathrin; Schauer, Jürgen; Steinle, Lea

    2013-04-01

    Marine methane hydrate is an ice-like substance stable at high-pressure and low temperature found frequently in continental margins. Since discovery of a large number of gas flares between 380 and 400 m water depth at the landward termination of the gas hydrate stability zone off Svalbard, there is concern that warming bottom waters have already started to melt large amounts of marine gas hydrate and may possibly accelerate global warming. The location of gas flares observed in PARASOUND data, geochemical anomalies in sediment cores, and anomalies in heat flow profiles suggest that hydrates play a role in the observed seepage of gas. However, the observation of thick carbonate crusts during manned submersible dives and their subsequent dating suggest that seepage off Svalbard has been ongoing for at least several hundred years and that decadal scale warming of the West Svalbard Current is at most of minor importance for the bulk of the observed seepage. Thus, the seeps off Svalbard do not necessarily represent the beginning of large-scale hydrate dissociation in the Arctic. Instead, it is likely that seasonal bottom water temperature fluctuations of 1-2°C cause periodic gas hydrate formation and dissociation, which focuses seepage at the observed gas flare depth. The results show that hydrate is highly sensitive to bottom water temperature changes and that bottom water warming will affect the stability of any large hydrate accumulations at the seabed on a short time scale.

  20. Solute-Solvent Charge-Transfer Excitations and Optical Absorption of Hydrated Hydroxide from Time-Dependent Density-Functional Theory.

    PubMed

    Opalka, Daniel; Sprik, Michiel

    2014-06-10

    The electronic structure of simple hydrated ions represents one of the most challenging problems in electronic-structure theory. Spectroscopic experiments identified the lowest excited state of the solvated hydroxide as a charge-transfer-to-solvent (CTTS) state. In the present work we report computations of the absorption spectrum of the solvated hydroxide ion, treating both solvent and solute strictly at the same level of theory. The average absorption spectrum up to 25 eV has been computed for samples taken from periodic ab initio molecular dynamics simulations. The experimentally observed CTTS state near the onset of the absorption threshold has been analyzed at the generalized-gradient approximation (GGA) and with a hybrid density-functional. Based on results for the lowest excitation energies computed with the HSE hybrid functional and a Davidson diagonalization scheme, the CTTS transition has been found 0.6 eV below the first absorption band of liquid water. The transfer of an electron to the solvent can be assigned to an excitation from the solute 2pπ orbitals, which are subject to a small energetic splitting due to the asymmetric solvent environment, to the significantly delocalized lowest unoccupied orbital of the solvent. The distribution of the centers of the excited state shows that CTTS along the OH(-) axis of the hydroxide ion is avoided. Furthermore, our simulations indicate that the systematic error arising in the calculated spectrum at the GGA originates from a poor description of the valence band energies in the solution.

  1. The effects of ice on methane hydrate nucleation: a microcanonical molecular dynamics study.

    PubMed

    Zhang, Zhengcai; Guo, Guang-Jun

    2017-07-26

    Although ice powders are widely used in gas hydrate formation experiments, the effects of ice on hydrate nucleation and what happens in the quasi-liquid layer of ice are still not well understood. Here, we used high-precision constant energy molecular dynamics simulations to study methane hydrate nucleation from vapor-liquid mixtures exposed to the basal, prismatic, and secondary prismatic planes of hexagonal ice (ice Ih). Although no significant difference is observed in hydrate nucleation processes for these different crystal planes, it is found, more interestingly, that methane hydrate can nucleate either on the ice surface heterogeneously or in the bulk solution phase homogeneously. Several factors are mentioned to be able to promote the heterogeneous nucleation of hydrates, including the adsorption of methane molecules at the solid-liquid interface, hydrogen bonding between hydrate cages and the ice structure, the stronger ability of ice to transfer heat than that of the aqueous solution, and the higher occurrence probability of hydrate cages in the vicinity of the ice surface than in the bulk solution. Meanwhile, however, the other factors including the hydrophilicity of ice and the ice lattice mismatch with clathrate hydrates can inhibit heterogeneous nucleation on the ice surface and virtually promote homogeneous nucleation in the bulk solution. Certainly, the efficiency of ice as a promoter and as an inhibitor for heterogeneous nucleation is different. We estimate that the former is larger than the latter under the working conditions. Additionally, utilizing the benefit of ice to absorb heat, the NVE simulation of hydrate formation with ice can mimic the phenomenon of ice shrinking during the heterogeneous nucleation of hydrates and lower the overly large temperature increase during homogeneous nucleation. These results are helpful in understanding the nucleation mechanism of methane hydrate in the presence of ice.

  2. Low dose powdered activated carbon addition at high sludge retention times to reduce fouling in membrane bioreactors.

    PubMed

    Remy, Maxime; van der Marel, Perry; Zwijnenburg, Arie; Rulkens, Wim; Temmink, Hardy

    2009-02-01

    The addition of a low concentration of PAC (0.5gL(-1) of sludge, i.e. a dose of 4mgL(-1) of wastewater), in combination with a relatively long SRT (50 days), to improve membrane filtration performance was investigated in two pilot-scale MBRs treating real municipal wastewater. Continuous filterability tests at high flux showed the possibility to run for 18h at 72Lm(-2)h(-1) and 180h at 50Lm(-2)h(-1), while significant fouling occurred without PAC. In addition, measurements of the critical flux showed an increase of 10% for this strategy. Low dosage and high retention time makes it feasible and cost effective. Further advantages with regard to permeate quality and possible micropollutants removal are currently under investigation.

  3. Structure and conductivity of epitaxial thin films of barium ferrite and its hydrated form BaFeO2.5‑x+δ (OH)2x

    NASA Astrophysics Data System (ADS)

    Anitha Sukkurji, Parvathy; Molinari, Alan; Benes, Alexander; Loho, Christoph; Sai Kiran Chakravadhanula, Venkata; Garlapati, Suresh Kumar; Kruk, Robert; Clemens, Oliver

    2017-03-01

    Barium ferrite and its hydrated form (BaFeO2.5‑x+δ (OH)2x , BFO) is an interesting cathode material for protonic ceramic fuel cells (PCFC) due to its potential to be both, conducting for electrons and protons. We report on the fabrication of almost epitaxially grown thin films (22 nm) of barium ferrite BaFeO~2.5 (BFO) on Nb-doped SrTiO3 substrates via pulsed laser deposition (PLD), followed by treatment under inert, and subsequently wet inert atmospheres to induce water (respectively proton) incorporation. Microstructure, chemical composition and conducting properties are investigated for the BFO films and their hydrated forms, highlighting the influence of hydration on the conductivity characteristics between ~200–290 K. We find that water incorporation gives a strong enhancement of the conductivity to ~10‑9 S cm‑1 compared to argon annealed films, inducing electronic and protonic charge carriers at the same time. In comparison to bulk powders, proton conductivity is found to be strongly suppressed in such thin hydrated BFO films, pointing towards the influence of strain on the conductivity, which is evaluated based on a detailed investigation by high-resolution transmission electron microscopy.

  4. Structure and collective dynamics of hydrated anti-freeze protein type III from 180 K to 298 K by X-ray diffraction and inelastic X-ray scattering

    NASA Astrophysics Data System (ADS)

    Yoshida, Koji; Baron, Alfred Q. R.; Uchiyama, Hiroshi; Tsutsui, Satoshi; Yamaguchi, Toshio

    2016-04-01

    We investigated hydrated antifreeze protein type III (AFP III) powder with a hydration level h (=mass of water/mass of protein) of 0.4 in the temperature range between 180 K and 298 K using X-ray diffraction and inelastic X-ray scattering (IXS). The X-ray diffraction data showed smooth, largely monotonic changes between 180 K and 298 K without freezing water. Meanwhile, the collective dynamics observed by IXS showed a strong change in the sound velocity at 180 K, after being largely temperature independent at higher temperatures (298-220 K). We interpret this change in terms of the dynamic transition previously discussed using other probes including THz IR absorption spectroscopy and incoherent elastic and quasi-elastic neutron scattering. This finding suggests that the dynamic transition of hydrated proteins is observable on the subpicosecond time scale as well as nano- and pico-second scales, both in collective dynamics from IXS and single particle dynamics from neutron scattering. Moreover, it is most likely that the dynamic transition of hydrated AFP III is not directly correlated with its hydration structure.

  5. Structure and collective dynamics of hydrated anti-freeze protein type III from 180 K to 298 K by X-ray diffraction and inelastic X-ray scattering.

    PubMed

    Yoshida, Koji; Baron, Alfred Q R; Uchiyama, Hiroshi; Tsutsui, Satoshi; Yamaguchi, Toshio

    2016-04-07

    We investigated hydrated antifreeze protein type III (AFP III) powder with a hydration level h (=mass of water/mass of protein) of 0.4 in the temperature range between 180 K and 298 K using X-ray diffraction and inelastic X-ray scattering (IXS). The X-ray diffraction data showed smooth, largely monotonic changes between 180 K and 298 K without freezing water. Meanwhile, the collective dynamics observed by IXS showed a strong change in the sound velocity at 180 K, after being largely temperature independent at higher temperatures (298-220 K). We interpret this change in terms of the dynamic transition previously discussed using other probes including THz IR absorption spectroscopy and incoherent elastic and quasi-elastic neutron scattering. This finding suggests that the dynamic transition of hydrated proteins is observable on the subpicosecond time scale as well as nano- and pico-second scales, both in collective dynamics from IXS and single particle dynamics from neutron scattering. Moreover, it is most likely that the dynamic transition of hydrated AFP III is not directly correlated with its hydration structure.

  6. Resin-Powder Dispenser

    NASA Technical Reports Server (NTRS)

    Standfield, Clarence E.

    1994-01-01

    Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

  7. Drilling Gas Hydrates on hydrate Ridge, Oregon continental margin

    NASA Astrophysics Data System (ADS)

    Trehu, A. M.; Bohrmann, G.; Leg 204 Science Party

    2002-12-01

    During Leg 204, we cored and logged 9 sites on the Oregon continental margin to determine the distribution and concentration of gas hydrates in an accretionary ridge and adjacent slope basin, investigate the mechanisms that transport methane and other gases into the gas hydrate stability zone (GHSZ), and obtain constraints on physical properties of hydrates in situ. A 3D seismic survey conducted in 2000 provided images of potential subsurface fluid conduits and indicated the position of the GHSZ throughout the survey region. After coring the first site, we acquired Logging-While-Drilling (LWD) data at all but one site to provide an overview of downhole physical properties. The LWD data confirmed the general position of key seismic stratigraphic horizons and yielded an initial estimate of hydrate concentration through the proxy of in situ electrical resistivity. These records proved to be of great value in planning subsequent coring. The second new hydrate proxy to be tested was infrared thermal imaging of cores on the catwalk as rapidly as possible after retrieval. The thermal images were used to identify hydrate samples and to estimate the distribution and texture of hydrate within the cores. Geochemical analyses of interstitial waters and of headspace and void gases provide additional information on the distribution and concentration of hydrate within the stability zone, the origin and pathway of fluids into and through the GHSZ, and the rates at which gas hydrate is forming. Bio- and lithostratigraphic description of cores, measurement of physical properties, and in situ pressure core sampling and thermal measurements complement the data set, providing ground-truth tests of inferred physical and sedimentological properties. Among the most interesting preliminary results are: 1) that gas hydrates are distributed through a broad depth range within the GHSZ and that different physical and chemical proxies for hydrate distribution and concentration give generally

  8. Direct real-time PCR with ethidium monoazide: a method for the rapid detection of viable Cronobacter sakazakii in powdered infant formula.

    PubMed

    Minami, Jun-Ichi; Soejima, Takashi; Yaeshima, Tomoko; Iwatsuki, Keiji

    2012-09-01

    The goal of this study was to establish a rapid assay for the specific detection of viable Cronobacter sakazakii in powdered infant formula (PIF). Samples were subjected to treatment multiple times with ethidium monoazide with a concentration gradient (gEMA) prior to PCR to discriminate viable from dead C. sakazakii cells. To improve the current detection limits, we developed a new buffer for direct quantitative real-time PCR (DqPCR) without DNA isolation. Using 17 PIF samples, our rapid assay was compared with the new U.S. Food and Drug Administration (FDA) method published in the Bacteriological Analytical Manual in 2012. Although both the new FDA method and our rapid assay, which consists of DqPCR combined with gEMA (gEMA-DqPCR), produced negative results for all 17 PIF samples, 5 of the 17 PIFs were positive by DqPCR when they were not treated with EMA. Furthermore, for PIF samples artificially contaminated with viable C. sakazakii, gEMA-DqPCR successfully detected between 1 and 9 CFU of viable C. sakazakii in 300 g of PIF within 9 h, including a 6-h preincubation. Our results indicate that multiple EMA treatments are required to avoid false-positive results due to the contamination of commercial PIF with dead or injured C. sakazakii cells. Our rapid assay may also improve the sensitivity of the screening portion required by the new FDA method published in the Bacteriological Analytical Manual in 2012.

  9. Effects of reheating time on microstructure and tensile properties of SiCp/2024 Al-based composites fabricated using powder thixoforming

    NASA Astrophysics Data System (ADS)

    Li, Pu Bo; Chen, Ti Jun; Zhang, Su Qing

    2017-01-01

    The present investigation addresses a new technology, named powder thixoforming, used to fabricate SiCp/2024 Al-based composites. The effects of reheating time on microstructure and mechanical properties have been studied. The results indicated that the quantity of liquid, the coarsening behavior of the primary particles, the subsequent plastic deformation occurring during thixoforging, and thus the resulting microstructural compactness and mechanical properties changed as a function of reheating time. The best comprehensive tensile properties of the composite, that is an ultimate tensile strength of 370 MPa and an elongation of 4.4%, were obtained after reheating for 80 min at 625 °C, which was an increase of 23.3% and a decrease of 57.7%, respectively, compared to the 2024 alloy thixoforged under the same conditions as the composite. The fracturing in the composites occurred through interconnecting cracked SiCp and debonded SiC/Al interfaces caused by a higher concentration of stress and a coalescence of microvoids.

  10. Estimation of Crystallinity of Nifedipine-Polyvinylpyrrolidone Solid Dispersion by Usage of Terahertz Time-Domain Spectroscopy and of X-Ray Powder Diffractometer.

    PubMed

    Takeuchi, Issei; Shimakura, Kemmaro; Kuroda, Hideki; Nakajima, Takehisa; Goto, Satoru; Makino, Kimiko

    2015-12-01

    Crystalline state of pharmaceutical materials is of great importance in preparation of pharmaceutics, because their physicochemical properties affect bioavailability, quality of products, therapeutic level and manufacturing process. In this study, we have estimated time-dependent changes of nifedipine in nifedipine-polyvinylpyrrolidone (PVP) solid dispersion by measuring terahertz time-domain spectroscopy (THz-TDS) and by X-ray powder diffractometry (XRPD), and compared their correlativity. Crystallinity of nifedipine-PVP solid dispersion was changed by storing the amorphous sample at 25°C-75°C and relative humidity of over 80% for 0.25-24.00 h. To compare the results of two types of measurements, we have used a general method of linear regression analysis. Crystallinities estimated using THz-TDS were plotted on the x-axis and that of XRPD were on the y-axis. From the result of the calculation, the correlativity of them was confirmed. THz-TDS has the capability of becoming the replacement of XRPD. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  11. UV254 absorbance as real-time monitoring and control parameter for micropollutant removal in advanced wastewater treatment with powdered activated carbon.

    PubMed

    Altmann, Johannes; Massa, Lukas; Sperlich, Alexander; Gnirss, Regina; Jekel, Martin

    2016-05-01

    This study investigates the applicability of UV absorbance measurements at 254 nm (UVA254) to serve as a simple and reliable surrogate parameter to monitor and control the removal of organic micropollutants (OMPs) in advanced wastewater treatment applying powdered activated carbon (PAC). Correlations between OMP removal and corresponding UVA254 reduction were determined in lab-scale adsorption batch tests and successfully applied to a pilot-scale PAC treatment stage to predict OMP removals in aggregate samples with good accuracy. Real-time UVA254 measurements were utilized to evaluate adapted PAC dosing strategies and proved to be effective for online monitoring of OMP removal. Furthermore, active PAC dosing control according to differential UVA254 measurements was implemented and tested. While precise removal predictions based on real-time measurements were not accurate for all OMPs, UVA254-controlled dynamic PAC dosing was capable of achieving stable OMP removals. UVA254 can serve as an effective surrogate parameter for OMP removal in technical PAC applications. Even though the applicability as control parameter to adjust PAC dosing to water quality changes might be limited to applications with fast response between PAC adjustment and adsorptive removal (e.g. direct filtration), UVA254 measurements can also be used to monitor the adsorption efficiency in more complex PAC applications.

  12. Preparation of titanium diboride powder

    DOEpatents

    Brynestad, Jorulf; Bamberger, Carlos E.

    1985-01-01

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  13. Preparation of metal diboride powders

    DOEpatents

    Brynestad, J.; Bamberger, C.E.

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group of consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  14. Nondestructive evaluation of crystallized-particle size in lactose-powder by terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamauchi, Satoshi; Hatakeyama, Sakura; Imai, Yoh; Tonouchi, Masayoshi

    2014-03-01

    Transmission-type terahertz time-domain spectroscopy is applied to evaluate crystallized lactose particle of size below 30 μm, which is far too small compared to the wavelength of incident terahertz (THz)-wave. The THz-absorption spectrum of lactose is successfully deconvoluted by Lorentzian to two spectra with peaks at 17.1 cm-1 (0.53 THz) and 45.6 cm-1 (1.37 THz) derived from α-lactose monohydrate, and a spectrum at 39.7 cm-1 (1.19 THz) from anhydrous β-lactose after removal of the broad-band spectrum by polynomial cubic function. Lactose is mainly crystallized into α-lactose monohydrate from the supersaturated solution at room temperature with a small amount of anhydrous β-lactose below 4%. The absorption feature is dependent on the crystallized particle size and the integrated intensity ratio of the two absorptions due to α-lactose monohydrate is correlated in linear for the size.

  15. Natural Gas Evolution in a Gas Hydrate Melt: Effect of Thermodynamic Hydrate Inhibitors.

    PubMed

    Sujith, K S; Ramachandran, C N

    2017-01-12

    Natural gas extraction from gas hydrate sediments by injection of hydrate inhibitors involves the decomposition of hydrates. The evolution of dissolved gas from the hydrate melt is an important step in the extraction process. Using classical molecular dynamics simulations, we study the evolution of dissolved methane from its hydrate melt in the presence of two thermodynamic hydrate inhibitors, NaCl and CH3OH. An increase in the concentration of hydrate inhibitors is found to promote the nucleation of methane nanobubbles in the hydrate melt. Whereas NaCl promotes bubble formation by enhancing the hydrophobic interaction between aqueous CH4 molecules, CH3OH molecules assist bubble formation by stabilizing CH4 bubble nuclei formed in the solution. The CH3OH molecules accumulate around the nuclei leading to a decrease in the surface tension at their interface with water. The nanobubbles formed are found to be highly dynamic with frequent exchange of CH4 molecules between the bubble and the surrounding liquid. A quantitative analysis of the dynamic behavior of the bubble is performed by introducing a unit step function whose value depends on the location of CH4 molecules with respect to the bubble. It is observed that an increase in the concentration of thermodynamic hydrate inhibitors reduces the exchange process, making the bubble less dynamic. It is also found that for a given concentration of the inhibitor, larger bubbles are less dynamic compared to smaller ones. The dependence of the dynamic nature of nanobubbles on bubble size and inhibitor concentration is correlated with the solubility of CH4 and the Laplace pressure within the bubble. The effect of CO2 on the formation of nanobubble in the CH4-CO2 mixed gas hydrate melt in the presence of inhibitors is also examined. The simulations show that the presence of CO2 molecules significantly reduces the induction time for methane nanobubble nucleation. The role of CO2 in the early nucleation of bubble is explained

  16. Simulation of subsea gas hydrate exploitation

    NASA Astrophysics Data System (ADS)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2014-05-01

    The recovery of methane from gas hydrate layers that have been detected in several subsea sediments and permafrost regions around the world is a promising perspective to overcome future shortages in natural gas supply. Being aware that conventional natural gas resources are limited, research is going on to develop technologies for the production of natural gas from such new sources. Thus various research programs have started since the early 1990s in Japan, USA, Canada, India, and Germany to investigate hydrate deposits and develop required technologies. In recent years, intensive research has focussed on the capture and storage of CO2 from combustion processes to reduce climate impact. While different natural or man-made reservoirs like deep aquifers, exhausted oil and gas deposits or other geological formations are considered to store gaseous or liquid CO2, the storage of CO2 as hydrate in former methane hydrate fields is another promising alternative. Due to beneficial stability conditions, methane recovery may be well combined with CO2 storage in the form of hydrates. Regarding technological implementation many problems have to be overcome. Especially mixing, heat and mass transfer in the reservoir are limiting factors causing very long process times. Within the scope of the German research project »SUGAR« different technological approaches for the optimized exploitation of gas hydrate deposits are evaluated and compared by means of dynamic system simulations and analysis. Detailed mathematical models for the most relevant chemical and physical processes are developed. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into simulation programs. Simulations based on geological field data have been carried out. The studies focus on the potential of gas production from turbidites and their fitness for CO2 storage. The effects occurring during gas production and CO2 storage within

  17. Global occurrences of gas hydrate

    USGS Publications Warehouse

    Kvenvolden, K.A.; Lorenson, T.D.

    2001-01-01

    Natural gas hydrate is found worldwide in sediments of outer continental margins of all oceans and in polar areas with continuous permafrost. There are currently 77 localities identified globally where geophysical, geochemical and/or geological evidence indicates the presence of gas hydrate. Details concerning individual gas-hydrate occurrences are compiled at a new world-wide-web (www) site (http://walrus.wr.usgs.gov/globalhydrate). This site has been created to facilitate global gas-hydrate research by providing information on each of the localities where there is evidence for gas hydrate. Also considered are the implications of gas hydrate as a potential (1) energy resource, (2) factor in global climate change, and (3) geohazard.

  18. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

    NASA Astrophysics Data System (ADS)

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; Hillman, Jess I. T.; Malinverno, Alberto

    2017-02-01

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1-20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two-dimensional and basin-scale three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. Furthermore, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.Plain Language SummaryThis study combines one-, two-, and three-dimensional simulations to explore one potential process by which methane dissolved in water beneath the seafloor can be converted into solid methane <span class="hlt">hydrate</span>. This work specifically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5697078','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/5697078"><span>Gas <span class="hlt">hydrate</span> cool storage system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ternes, M.P.; Kedl, R.J.</p> <p>1984-09-12</p> <p>The invention presented relates to the development of a process utilizing a gas <span class="hlt">hydrate</span> as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas <span class="hlt">hydrate</span> as storage material in a thermal energy storage system within a heat pump cycle system. The gas <span class="hlt">hydrate</span> was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5050772','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5050772"><span>Glycine zinc sulfate penta­<span class="hlt">hydrate</span>: redetermination at 10 K from <span class="hlt">time</span>-of-flight neutron Laue diffraction</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fortes, A. Dominic; Howard, Christopher M.; Wood, Ian G.; Gutmann, Matthias J.</p> <p>2016-01-01</p> <p>Single crystals of glycine zinc sulfate penta­<span class="hlt">hydrate</span> [systematic name: hexa­aqua­zinc tetra­aquadiglycinezinc bis­(sulfate)], [Zn(H2O)6][Zn(C2H5NO2)2(H2O)4](SO4)2, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octa­hedra on sites of symmetry -1 and two SO4 tetra­hedra with site symmetry 1; the octa­hedra comprise one [tetra­aqua-diglycine zinc]2+ ion (centred on one Zn atom) and one [hexa­aqua­zinc]2+ ion (centred on the other Zn atom); the glycine zwitterion, NH3 +CH2COO−, adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N—H⋯O hydrogen bonds between the amine and carboxyl­ate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate inter­nuclear X—H (X = N, O) bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework. PMID:27746937</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1286756','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1286756"><span>High-pressure dynamics of <span class="hlt">hydrated</span> protein in bioprotective trehalose environment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Diallo, S. O.; Zhang, Q.; O'Neill, H.; Mamontov, E.</p> <p>2014-10-30</p> <p>Here we present a pressure-dependence study of the dynamics of lysozyme protein <span class="hlt">powder</span> immersed in deuterated , α-trehalose environment via quasielastic neutron scattering (QENS). The goal is to assess the baroprotective benefits of trehalose on biomolecules by comparing the findings with those of a trehalose-free reference study. While the mean-square displacement of the trehalose-free protein (<span class="hlt">hydrated</span> to d<sub>D₂O</sub> ≃40 w%) as a whole, is reduced by increasing pressure, the actual observable relaxation dynamics in the picoseconds to nanoseconds <span class="hlt">time</span> range remains largely unaffected by pressure up to the maximum investigated pressure of 2.78(2) Kbar. Our observation is independent of whether or not the protein is mixed with the deuterated sugar. This suggests that the <span class="hlt">hydrated</span> protein s conformational states at atmospheric pressure remain unaltered by hydrostatic pressures, below 2.78 Kbar. We also found the QENS response to be totally recoverable after ambient pressure conditions are restored. Small-angle neutron diffraction measurements confirm that the protein-protein correlation remains undisturbed.We observe, however, a clear narrowing of the QENS response as the temperature is decreased from 290 to 230 K in both cases, which we parametrize using the Kohlrausch-Williams-Watts stretched exponential model. Finally, only the fraction of protons that are immobile on the accessible <span class="hlt">time</span> window of the instrument, referred to as the elastic incoherent structure factor, is observably sensitive to pressure, increasing only marginally but systematically with increasing pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25375541','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25375541"><span>High-pressure dynamics of <span class="hlt">hydrated</span> protein in bioprotective trehalose environment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Diallo, S O; Zhang, Q; O'Neill, H; Mamontov, E</p> <p>2014-10-01</p> <p>We present a pressure-dependence study of the dynamics of lysozyme protein <span class="hlt">powder</span> immersed in deuterated α,α-trehalose environment via quasielastic neutron scattering (QENS). The goal is to assess the baroprotective benefits of trehalose on biomolecules by comparing the findings with those of a trehalose-free reference study. While the mean-square displacement of the trehalose-free protein (<span class="hlt">hydrated</span> to dD2O≃40 w%) as a whole, is reduced by increasing pressure, the actual observable relaxation dynamics in the picoseconds to nanoseconds <span class="hlt">time</span> range remains largely unaffected by pressure--up to the maximum investigated pressure of 2.78(2) Kbar. Our observation is independent of whether or not the protein is mixed with the deuterated sugar. This suggests that the <span class="hlt">hydrated</span> protein's conformational states at atmospheric pressure remain unaltered by hydrostatic pressures, below 2.78 Kbar. We also found the QENS response to be totally recoverable after ambient pressure conditions are restored. Small-angle neutron diffraction measurements confirm that the protein-protein correlation remains undisturbed. We observe, however, a clear narrowing of the QENS response as the temperature is decreased from 290 to 230 K in both cases, which we parametrize using the Kohlrausch-Williams-Watts stretched exponential model. Only the fraction of protons that are immobile on the accessible <span class="hlt">time</span> window of the instrument, referred to as the elastic incoherent structure factor, is observably sensitive to pressure, increasing only marginally but systematically with increasing pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvE..90d2725D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvE..90d2725D"><span>High-pressure dynamics of <span class="hlt">hydrated</span> protein in bioprotective trehalose environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diallo, S. O.; Zhang, Q.; O'Neill, H.; Mamontov, E.</p> <p>2014-10-01</p> <p>We present a pressure-dependence study of the dynamics of lysozyme protein <span class="hlt">powder</span> immersed in deuterated α ,α -trehalose environment via quasielastic neutron scattering (QENS). The goal is to assess the baroprotective benefits of trehalose on biomolecules by comparing the findings with those of a trehalose-free reference study. While the mean-square displacement of the trehalose-free protein (<span class="hlt">hydrated</span> to dD2O≃ 40 w%) as a whole, is reduced by increasing pressure, the actual observable relaxation dynamics in the picoseconds to nanoseconds <span class="hlt">time</span> range remains largely unaffected by pressure—up to the maximum investigated pressure of 2.78(2) Kbar. Our observation is independent of whether or not the protein is mixed with the deuterated sugar. This suggests that the <span class="hlt">hydrated</span> protein's conformational states at atmospheric pressure remain unaltered by hydrostatic pressures, below 2.78 Kbar. We also found the QENS response to be totally recoverable after ambient pressure conditions are restored. Small-angle neutron diffraction measurements confirm that the protein-protein correlation remains undisturbed. We observe, however, a clear narrowing of the QENS response as the temperature is decreased from 290 to 230 K in both cases, which we parametrize using the Kohlrausch-Williams-Watts stretched exponential model. Only the fraction of protons that are immobile on the accessible <span class="hlt">time</span> window of the instrument, referred to as the elastic incoherent structure factor, is observably sensitive to pressure, increasing only marginally but systematically with increasing pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS43A1781C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS43A1781C"><span>Kinetics Characteristics of Nitrogen <span class="hlt">Hydrates</span> Respond to Differential Scanning Calorimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Q.; Liu, C.; Ye, Y.; Gong, J.</p> <p>2012-12-01</p> <p> a function of <span class="hlt">time</span> can be obtained by integrating the exothermic peaks. As a series of experiments were carried out using the same bulk phase, these curves represented a semi-quantitative result of <span class="hlt">hydrate</span> crystal growth speed (see Figure 1). The slope of the energy curve reflected the growth speed at a certain <span class="hlt">time</span>. The steeper the curve became, the faster the <span class="hlt">hydrates</span> growth was. As could be expected, <span class="hlt">hydrate</span> growth speed is extremely dependent of the sub-cooling.; Figure 1. Energy released of <span class="hlt">hydrates</span> growth as a function of <span class="hlt">time</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4858699','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4858699"><span>Computational investigation of dynamical transitions in Trp-cage miniprotein <span class="hlt">powders</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Sang Beom; Gupta, Devansh R.; Debenedetti, Pablo G.</p> <p>2016-01-01</p> <p>We investigate computationally the dynamical transitions in Trp-cage miniprotein <span class="hlt">powders</span>, at three levels of <span class="hlt">hydration</span>: 0.04, 0.26 and 0.4 g water/g protein. We identify two distinct temperatures where transitions in protein dynamics occur. Thermal motions are harmonic and independent of <span class="hlt">hydration</span> level below Tlow ≈ 160 K, above which all <span class="hlt">powders</span> exhibit harmonic behavior but with a different and enhanced temperature dependence. The second onset, which is often referred to as the protein dynamical transition, occurs at a higher temperature TD that decreases as the <span class="hlt">hydration</span> level increases, and at the lowest <span class="hlt">hydration</span> level investigated here (0.04 g/g) is absent in the temperature range we studied in this work (T ≤ 300 K). Protein motions become anharmonic at TD, and their amplitude increases with <span class="hlt">hydration</span> level. Upon heating above TD, hydrophilic residues experience a pronounced enhancement in the amplitude of their characteristic motions in <span class="hlt">hydrated</span> <span class="hlt">powders</span>, whereas it is the hydrophobic residues that experience the more pronounced enhancement in the least <span class="hlt">hydrated</span> system. The dynamical transition in Trp-cage is a collective phenomenon, with every residue experiencing a transition to anharmonic behavior at the same temperature. PMID:27151767</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...625612K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...625612K"><span>Computational investigation of dynamical transitions in Trp-cage miniprotein <span class="hlt">powders</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Sang Beom; Gupta, Devansh R.; Debenedetti, Pablo G.</p> <p>2016-05-01</p> <p>We investigate computationally the dynamical transitions in Trp-cage miniprotein <span class="hlt">powders</span>, at three levels of <span class="hlt">hydration</span>: 0.04, 0.26 and 0.4 g water/g protein. We identify two distinct temperatures where transitions in protein dynamics occur. Thermal motions are harmonic and independent of <span class="hlt">hydration</span> level below Tlow ≈ 160 K, above which all <span class="hlt">powders</span> exhibit harmonic behavior but with a different and enhanced temperature dependence. The second onset, which is often referred to as the protein dynamical transition, occurs at a higher temperature TD that decreases as the <span class="hlt">hydration</span> level increases, and at the lowest <span class="hlt">hydration</span> level investigated here (0.04 g/g) is absent in the temperature range we studied in this work (T ≤ 300 K). Protein motions become anharmonic at TD, and their amplitude increases with <span class="hlt">hydration</span> level. Upon heating above TD, hydrophilic residues experience a pronounced enhancement in the amplitude of their characteristic motions in <span class="hlt">hydrated</span> <span class="hlt">powders</span>, whereas it is the hydrophobic residues that experience the more pronounced enhancement in the least <span class="hlt">hydrated</span> system. The dynamical transition in Trp-cage is a collective phenomenon, with every residue experiencing a transition to anharmonic behavior at the same temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013740','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013740"><span>Geochemistry of a naturally occurring massive marine gas <span class="hlt">hydrate</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kvenvolden, K.A.; Claypool, G.E.; Threlkeld, C.N.; Dendy, Sloan E.</p> <p>1984-01-01</p> <p>During Deep Sea Drilling Project (DSDP) Leg 84 a core 1 m long and 6 cm in diameter of massive gas <span class="hlt">hydrate</span> was unexpectedly recovered at Site 570 in upper slope sediment of the Middle America Trench offshore of Guatemala. This core contained only 5-7% sediment, the remainder being the solid <span class="hlt">hydrate</span> composed of gas and water. Samples of the gas <span class="hlt">hydrate</span> were decomposed under controlled conditions in a closed container maintained at 4??C. Gas pressure increased and asymptotically approached the equilibrium decomposition pressure for an ideal methane <span class="hlt">hydrate</span>, CH4.5-3/4H2O, of 3930 kPa and approached to this pressure after each <span class="hlt">time</span> gas was released, until the gas <span class="hlt">hydrate</span> was completely decomposed. The gas evolved during <span class="hlt">hydrate</span> decomposition was 99.4% methane, ???0.2% ethane, and ???0.4% CO2. Hydrocarbons from propane to heptane were also present, but in concentrations of less than 100 p.p.m. The carbon-isotopic composition of methane was -41 to -44 permil(( 0 00), relative to PDB standard. The observed volumetric methane/water ratio was 64 or 67, which indicates that before it was stored and analyzed, the gas <span class="hlt">hydrate</span> probably had lost methane. The sample material used in the experiments was likely a mixture of methane <span class="hlt">hydrate</span> and water ice. Formation of this massive gas <span class="hlt">hydrate</span> probably involved the following processes: (i) upward migration of gas and its accumulation in a zone where conditions favored the growth of gas <span class="hlt">hydrates</span>, (ii) continued, unusually rapid biological generation of methane, and (iii) release of gas from water solution as pressure decreased due to sea level lowering and tectonic uplift. ?? 1984.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1912281','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1912281"><span>Kinetics of the barotropic ripple (P beta')/lamellar liquid crystal (L alpha) phase transition in fully <span class="hlt">hydrated</span> dimyristoylphosphatidylcholine (DMPC) monitored by <span class="hlt">time</span>-resolved x-ray diffraction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Caffrey, M; Hogan, J; Mencke, A</p> <p>1991-08-01</p> <p>We present here the first study of the use of a pressure-jump to induce the ripple (P beta')/lamellar liquid crystal (L alpha) phase transition in fully <span class="hlt">hydrated</span> 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The transition was monitored by using <span class="hlt">time</span>-resolved x-ray diffraction (TRXRD). Applying a pressure-jump from atmospheric to 11.3 MPa (1640 psig, 111.6 atm) in 2.5 s induces the L alpha to P beta' phase transition which takes place in two stages. The lamellar repeat spacing initially increases from a value of 66.0 +/- 0.1 A (n = 4) to a maximum value of 70.3 +/- 0.8 A (n = 4) after 10 s and after a further 100-150 s decreases slightly to 68.5 +/- 0.3 A (n = 4). The reverse transition takes place following a pressure jump in 5.5 s from 11.3 MPa to atmospheric pressure. Again, the transition occurs in two stages with the repeat spacing steadily decreasing from an initial value of 68.5 +/- 0.3 A (n = 3) to a minimum value of 66.6 +/- 0.3 A (n = 3) after 50 s and then increasing by approximately 0.5 A over a period of 100 s. The transition temperature increases linearly with pressure up to 14.1 MPa in accordance with the Clapeyron relation, giving a dT/dP value of 0.285 degrees C/MPa (28.5 degrees C/kbar) and an associated volume change of 40 microliters/g. A dynamic compressibility of 0.13 +/- 0.01 A/MPa has been determined for the L alpha phase. This value is compared with the equilibrium compressibilities of bilayer and nonbilayer phases reported in the literature. The results suggest testable mechanisms for the pressure-induced transition involving changes in periodicity, phase <span class="hlt">hydration</span>, chain order, and orientation. A more complete understanding of the transition mechanism will require improvement in detector spatial resolution and sensitivity, and data on the pressure sensitivity of phase <span class="hlt">hydration</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1260083','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1260083"><span>Kinetics of the barotropic ripple (P beta')/lamellar liquid crystal (L alpha) phase transition in fully <span class="hlt">hydrated</span> dimyristoylphosphatidylcholine (DMPC) monitored by <span class="hlt">time</span>-resolved x-ray diffraction.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Caffrey, M; Hogan, J; Mencke, A</p> <p>1991-01-01</p> <p>We present here the first study of the use of a pressure-jump to induce the ripple (P beta')/lamellar liquid crystal (L alpha) phase transition in fully <span class="hlt">hydrated</span> 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The transition was monitored by using <span class="hlt">time</span>-resolved x-ray diffraction (TRXRD). Applying a pressure-jump from atmospheric to 11.3 MPa (1640 psig, 111.6 atm) in 2.5 s induces the L alpha to P beta' phase transition which takes place in two stages. The lamellar repeat spacing initially increases from a value of 66.0 +/- 0.1 A (n = 4) to a maximum value of 70.3 +/- 0.8 A (n = 4) after 10 s and after a further 100-150 s decreases slightly to 68.5 +/- 0.3 A (n = 4). The reverse transition takes place following a pressure jump in 5.5 s from 11.3 MPa to atmospheric pressure. Again, the transition occurs in two stages with the repeat spacing steadily decreasing from an initial value of 68.5 +/- 0.3 A (n = 3) to a minimum value of 66.6 +/- 0.3 A (n = 3) after 50 s and then increasing by approximately 0.5 A over a period of 100 s. The transition temperature increases linearly with pressure up to 14.1 MPa in accordance with the Clapeyron relation, giving a dT/dP value of 0.285 degrees C/MPa (28.5 degrees C/kbar) and an associated volume change of 40 microliters/g. A dynamic compressibility of 0.13 +/- 0.01 A/MPa has been determined for the L alpha phase. This value is compared with the equilibrium compressibilities of bilayer and nonbilayer phases reported in the literature. The results suggest testable mechanisms for the pressure-induced transition involving changes in periodicity, phase <span class="hlt">hydration</span>, chain order, and orientation. A more complete understanding of the transition mechanism will require improvement in detector spatial resolution and sensitivity, and data on the pressure sensitivity of phase <span class="hlt">hydration</span>. PMID:1912281</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28055818','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28055818"><span><span class="hlt">Time</span>-Domain Nuclear Magnetic Resonance (TD-NMR) and Chemometrics for Determination of Fat Content in Commercial Products of Milk <span class="hlt">Powder</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nascimento, Paloma Andrade Martins; Barsanelli, Paulo Lopes; Rebellato, Ana Paula; Pallone, Juliana Azevedo Lima; Colnago, Luiz Alberto; Pereira, Fabíola Manhas Verbi</p> <p>2017-03-01</p> <p>This study shows the use of <span class="hlt">time</span>-domain (TD)-NMR transverse relaxation (T2) data and chemometrics in the nondestructive determination of fat content for <span class="hlt">powdered</span> food samples such as commercial dried milk products. Most proposed NMR spectroscopy methods for measuring fat content correlate free induction decay or echo intensities with the sample's mass. The need for the sample's mass limits the analytical frequency of NMR determination, because weighing the samples is an additional step in this procedure. Therefore, the method proposed here is based on a multivariate model of T2 decay, measured with Carr-Purcell-Meiboom-Gill pulse sequence and reference values of fat content. The TD-NMR spectroscopy method shows high correlation (r = 0.95) with the lipid content, determined by the standard extraction method of Bligh and Dyer. For comparison, fat content determination was also performed using a multivariate model with near-IR (NIR) spectroscopy, which is also a nondestructive method. The advantages of the proposed TD-NMR method are that it (1) minimizes toxic residue generation, (2) performs measurements with high analytical frequency (a few seconds per analysis), and (3) does not require sample preparation (such as pelleting, needed for NIR spectroscopy analyses) or weighing the samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24929809','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24929809"><span>Effects of sludge retention <span class="hlt">times</span> on reactivity of effluent dissolved organic matter for trihalomethane formation in hybrid <span class="hlt">powdered</span> activated carbon membrane bioreactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ma, Defang; Gao, Baoyu; Xia, Chufan; Wang, Yan; Yue, Qinyan; Li, Qian</p> <p>2014-08-01</p> <p>In this study, real municipal wastewater intended for reuse was treated by two identical hybrid PAC/MBRs (membrane bioreactors with <span class="hlt">powdered</span> activated carbon addition), which were operated at sludge retention <span class="hlt">times</span> (SRTs) of 30 and 180 days, respectively. In order to investigate the effects of SRT on trihalomethane (THM) formation in chlorinated PAC/MBR effluents, characteristics and THM formation reactivity of effluent dissolved organic matter (EfOM) at different SRTs were examined. PAC/MBR-180 had higher level of EfOM, which contained less simple aromatic proteins and exhibited lower specific UV absorbance. EfOM with molecular weight <5 kDa from PAC/MBR-30 (23%) was lower than PAC/MBR-180 (26%). About 50% of EfOM from PAC/MBR-30 was hydrophobic acids, which was higher than that from PAC/MBR-180 (about 36%). EfOM at SRT 180 days exhibited higher hydrophilicity. Prolonging SRT greatly reduced THM formation reactivity of EfOM, but increased the formation of bromine-containing species during chlorination of PAC/MBR effluents. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17995750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17995750"><span>Effects of vegetable juice <span class="hlt">powder</span> concentration and storage <span class="hlt">time</span> on some chemical and sensory quality attributes of uncured, emulsified cooked sausages.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sindelar, J J; Cordray, J C; Sebranek, J G; Love, J A; Ahn, D U</p> <p>2007-06-01</p> <p>Uncured, no-nitrate/nitrite-added meat products can be manufactured with vegetable juice <span class="hlt">powder</span> (VJP) and a starter culture containing Staphylococcus carnosus, resulting in quality and sensory attributes similar to traditional cured products. The 1st objective of this study was to determine the effects of varying concentrations of VJP and incubation <span class="hlt">times</span> (MIN-HOLD) on quality characteristics, including lipid oxidation, color, and cured meat pigment concentrations, of emulsified-frankfurter-style-cooked (EFSC) sausages over a 90-d storage period. The 2nd objective was to compare residual nitrate and nitrite content resulting from different processing treatments and the 3rd objective was to assess sensory properties of finished products. Four EFSC sausage treatments (TRT) (TRT 1: 0.20% VJP, 30 MIN-HOLD; TRT 2: 0.20% VJP, 120 MIN-HOLD; TRT 3: 0.40% VJP, 30 MIN-HOLD; TRT 4: 0.40% VJP, 120 MIN-HOLD) and a sodium nitrite-added control (C) were used for this study. No differences for lipid oxidation (TBARS) between any TRTs and C or over <span class="hlt">time</span> were observed. No differences (P > 0.05) for CIE L* values were found between TRTs. CIE a* and reflectance ratio values revealed that TRTs 2, 4, and C were redder than TRTs 1 and 3 at day 0. Trained sensory intensity ratings for cured aroma, cured color, cured flavor, uniform color, and firmness determined that all but TRT 1 were similar to C. These results indicate a longer incubation <span class="hlt">time</span> (120 compared with 30 min) was found more critical than VJP level (0.20% or 0.40%) to result in products comparable to a sodium nitrite-added control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/890656','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/890656"><span>Depressurization-induced gas production from Class 1 and Class 2<span class="hlt">hydrate</span> deposits</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moridis, George J.; Kowalsky, Michael</p> <p>2006-05-12</p> <p>Class 1 <span class="hlt">hydrate</span> deposits are characterized by a <span class="hlt">Hydrate</span>-Bearing Layer (HBL) underlain by a two-phase zone involving mobile gas. Such deposits are further divided to Class 1W (involving water and <span class="hlt">hydrate</span> in the HBL) and Class 1G (involving gas and <span class="hlt">hydrate</span> in the HBL). In Class 2 deposits, a mobile water zone underlies the <span class="hlt">hydrate</span> zone. Methane is the main <span class="hlt">hydrate</span>-forming gas in natural accumulations. Using TOUGH-FX/<span class="hlt">HYDRATE</span> to study the depressurization-induced gas production from such deposits, we determine that large volumes of gas could be readily produced at high rates for long <span class="hlt">times</span> using conventional technology. Dissociation in Class 1W deposits proceeds in distinct stages, but is continuous in Class 1G deposits. <span class="hlt">Hydrates</span> are shown to contribute significantly to the production rate (up to 65 percent and 75 percent in Class 1W and 1G, respectively) and to the cumulative volume of produced gas (up to 45 percent and 54 percent in Class 1W and 1G, respectively). Large volumes of <span class="hlt">hydrate</span>-originating CH4 could be produced from Class 2 <span class="hlt">hydrates</span>, but a relatively long lead <span class="hlt">time</span> would be needed before gas production (which continuously increases over <span class="hlt">time</span>) attains a substantial level. The permeability of the confining boundaries plays a significant role in gas production from Class 2 deposits. In general, long-term production is needed to realize the full potential of the very promising Class 1 and Class 2 <span class="hlt">hydrate</span> deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020046797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020046797"><span><span class="hlt">Hydrated</span> Minerals on Asteroids: The Astronomical Record</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.</p> <p>2002-01-01</p> <p>Knowledge of the <span class="hlt">hydrated</span> mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest <span class="hlt">times</span> in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5 micrometers regions, which are diagnostic of or associated with <span class="hlt">hydrated</span> minerals. Observations in those regions show that <span class="hlt">hydrated</span> minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings, as well. Asteroid groups formerly associated with mineralogies assumed to have high temperature formation, such as M- and E-class asteroids, have been observed to have <span class="hlt">hydration</span> features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and hydroxyl-bearing minerals on asteroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030014278&hterms=Steroids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSteroids','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030014278&hterms=Steroids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSteroids"><span><span class="hlt">Hydrated</span> Minerals on Asteroids: The Astronomical Record</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.</p> <p>2003-01-01</p> <p>Knowledge of the <span class="hlt">hydrated</span> mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest <span class="hlt">times</span> in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5-micron regions, which are diagnostic of or associated with <span class="hlt">hydrated</span> minerals. Observations in those regions show that <span class="hlt">hydrated</span> minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings as well. Asteroid groups formerly associated with mineralogies assumed to have high-temperature formation, such as M- and E-class steroids, have been observed to have <span class="hlt">hydration</span> features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and Hydroxl-bearing minerals on asteroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17388572','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17388572"><span>Hydroxide ion <span class="hlt">hydration</span> in aqueous solutions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smiechowski, Maciej; Stangret, Janusz</p> <p>2007-04-19</p> <p>Hydroxide ion <span class="hlt">hydration</span> was studied in aqueous solutions of selected alkali metal hydroxides by means of Fourier transform infrared (FTIR) spectroscopy of HDO isotopically diluted in H2O. The quantitative difference spectra procedure was applied for the first <span class="hlt">time</span> to investigate such systems. It allowed removal of bulk water contribution and separation of the spectra of solute-affected HDO. The obtained spectral data were confronted with ab initio calculated structures of small gas-phase and polarizable continuum solvation model (PCM) solvated aqueous clusters, OH-(H2O)n, n = 1-7, to establish the structural and energetic states of <span class="hlt">hydration</span> spheres of the <span class="hlt">hydrated</span> hydroxide anion. This was achieved by comparison of the calculated optimal geometries with the interatomic distances derived from HDO band positions. The energetic state of water in OH- <span class="hlt">hydration</span> shells, as revealed by solute-affected HDO spectra, is similar to that of an isoelectronic F- anion. No evidence was found for the existence of stable hydroxide dimer, H3O2-, in an aqueous solution. Spectral data do confirm, however, existence of a weak interaction with a single water molecule at the hydrogen site of OH-.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70027080','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70027080"><span>Dissolution rates of pure methane <span class="hlt">hydrate</span> and carbon-dioxide <span class="hlt">hydrate</span> in undersaturated seawater at 1000-m depth</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rehder, G.; Kirby, S.H.; Durham, W.B.; Stern, L.A.; Peltzer, E.T.; Pinkston, J.; Brewer, P.G.</p> <p>2004-01-01</p> <p>To help constrain models involving the chemical stability and lifetime of gas clathrate <span class="hlt">hydrates</span> exposed at the seafloor, dissolution rates of pure methane and carbon-dioxide <span class="hlt">hydrates</span> were measured directly on the seafloor within the nominal pressure-temperature (P/T) range of the gas <span class="hlt">hydrate</span> stability zone. Other natural boundary conditions included variable flow velocity and undersaturation of seawater with respect to the <span class="hlt">hydrate</span>-forming species. Four cylindrical test specimens of pure, polycrystalline CH4 and CO2 <span class="hlt">hydrate</span> were grown and fully compacted in the laboratory, then transferred by pressure vessel to the seafloor (1028 m depth), exposed to the deep ocean environment, and monitored for 27 hours using <span class="hlt">time</span>-lapse and HDTV cameras. Video analysis showed diameter reductions at rates between 0.94 and 1.20 ??m/s and between 9.0 and 10.6 ?? 10-2 ??m/s for the CO2 and CH4 <span class="hlt">hydrates</span>, respectively, corresponding to dissolution rates of 4.15 ?? 0.5 mmol CO2/m2s and 0.37 ?? 0.03 mmol CH4/m2s. The ratio of the dissolution rates fits a diffusive boundary layer model that incorporates relative gas solubilities appropriate to the field site, which implies that the kinetics of the dissolution of both <span class="hlt">hydrates</span> is diffusion-controlled. The observed dissolution of several mm (CH4) or tens of mm (CO2) of <span class="hlt">hydrate</span> from the sample surfaces per day has major implications for estimating the longevity of natural gas <span class="hlt">hydrate</span> outcrops as well as for the possible roles of CO2 <span class="hlt">hydrates</span> in marine carbon sequestration strategies. ?? 2003 Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JAESc..36..277G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JAESc..36..277G"><span>The methane <span class="hlt">hydrate</span> formation and the resource estimate resulting from free gas migration in seeping seafloor <span class="hlt">hydrate</span> stability zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guan, Jinan; Liang, Deqing; Wu, Nengyou; Fan, Shuanshi</p> <p>2009-10-01</p> <p>It is a typical multiphase flow process for <span class="hlt">hydrate</span> formation in seeping seafloor sediments. Free gas can not only be present but also take part in formation of <span class="hlt">hydrate</span>. The volume fraction of free gas in local pore of <span class="hlt">hydrate</span> stable zone (HSZ) influences the formation of <span class="hlt">hydrate</span> in seeping seafloor area, and methane flux determines the abundance and resource of <span class="hlt">hydrate</span>-bearing reservoirs. In this paper, a multiphase flow model including water (dissolved methane and salt)-free gas <span class="hlt">hydrate</span> has been established to describe this kind of flow-transfer-reaction process where there exists a large scale of free gas migration and transform in seafloor pore. In the order of three different scenarios, the conversions among permeability, capillary pressure, phase saturations and salinity along with the formation of <span class="hlt">hydrate</span> have been deducted. Furthermore, the influence of four sorts of free gas saturations and three classes of methane fluxes on <span class="hlt">hydrate</span> formation and the resource has also been analyzed and compared. Based on the rules drawn from the simulation, and combined information gotten from drills in field, the methane <span class="hlt">hydrate</span>(MH) formation in Shenhu area of South China Sea has been forecasted. It has been speculated that there may breed a moderate methane flux below this seafloor HSZ. If the flux is about 0.5 kg m -2 a -1, then it will go on to evolve about 2700 ka until the <span class="hlt">hydrate</span> saturation in pore will arrive its peak (about 75%). Approximately 1.47 × 10 9 m 3 MH has been reckoned in this marine basin finally, is about 13 <span class="hlt">times</span> over preliminary estimate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20770219','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20770219"><span>The growth rate of gas <span class="hlt">hydrate</span> from refrigerant R12</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kendoush, Abdullah Abbas; Jassim, Najim Abid; Joudi, Khalid A.</p> <p>2006-07-15</p> <p>Experimental and theoretical investigations were presented dealing with three phase direct-contact heat transfer by evaporation of refrigerant drops in an immiscible liquid. Refrigerant R12 was used as the dispersed phase, while water and brine were the immiscible continuous phase. A numerical solution is presented to predict the formation rate of gas <span class="hlt">hydrates</span> in test column. The solution provided an acceptable agreement when compared with experimental results. The gas <span class="hlt">hydrate</span> growth rate increased with <span class="hlt">time</span>. It increased with increasing dispersed phase flow rate. The presence of surface-active sodium chloride in water had a strong inhibiting effect on the gas <span class="hlt">hydrate</span> formation rate. (author)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS23B2005Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS23B2005Y"><span>Quantifying <span class="hlt">Hydrate</span> Formation in Gas-rich Environments Using the Method of Characteristics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>You, K.; Flemings, P. B.; DiCarlo, D. A.</p> <p>2015-12-01</p> <p>Methane <span class="hlt">hydrates</span> hold a vast amount of methane globally, and have huge energy potential. Methane <span class="hlt">hydrates</span> in gas-rich environments are the most promising production targets. We develop a one-dimensional analytical solution based on the method of characteristics to explore <span class="hlt">hydrate</span> formation in such environments (Figure 1). Our solution shows that <span class="hlt">hydrate</span> saturation is constant with <span class="hlt">time</span> and space in a homogeneous system. <span class="hlt">Hydrate</span> saturation is controlled by the initial thermodynamic condition of the system, and changed by the gas fractional flow. <span class="hlt">Hydrate</span> saturation increases with the initial distance from the <span class="hlt">hydrate</span> phase boundary. Different gas fractional flows behind the <span class="hlt">hydrate</span> solidification front lead to different gas saturations at the <span class="hlt">hydrate</span> solidification front. The higher the gas saturation at the front, the less the volume available to be filled by <span class="hlt">hydrate</span>, and hence the lower the <span class="hlt">hydrate</span> saturation. The gas fractional flow depends on the relative permeability curves, and the forces that drive the flow. Viscous forces (the drive for flow induced from liquid pressure gradient) dominate the flow, and <span class="hlt">hydrate</span> saturation is independent on the gas supply rates and the flow directions at high gas supply rates. <span class="hlt">Hydrate</span> saturation can be estimated as one minus the ratio of the initial to equilibrium salinity. Gravity forces (the drive for flow induced from the gravity) dominate the flow, and <span class="hlt">hydrate</span> saturation depends on the flow rates and the flow directions at low gas supply rates. <span class="hlt">Hydrate</span> saturation is highest for upward flow, and lowest for downward flow. <span class="hlt">Hydrate</span> saturation decreases with the flow rate for upward flow, and increases with the flow rate for downward flow. This analytical solution illuminates how <span class="hlt">hydrate</span> is formed by gas (methane, CO2, ethane, propane) flowing into brine-saturated sediments at both the laboratory and geological scales (Figure 1). It provides an approach to generalize the understanding of <span class="hlt">hydrate</span> solidification in gas</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28926716','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28926716"><span>Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) - A novel approach to investigate the wettability of pharmaceutical <span class="hlt">powder</span> blends.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peddapatla, Raghu V G; Ahmed, M Rizwan; Blackshields, Caroline A; Sousa-Gallagher, M J; McSweeney, Sean; Krüse, J; Crean, Abina M; Fitzpatrick, Dara</p> <p>2017-09-19</p> <p>The ability of Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) to assess the wettability of <span class="hlt">powder</span> blends is investigated. BARDS is a novel analytical technology developed based on the change in acoustic phenomenon observed when material is added into a solvent under resonance. Addition of solid material to the solvent results in the introduction of gas (air) into the solvent, changing the compressibility of the solvent system and reducing the velocity of sound in the solvent. As a material is wetted and dissolved, the gas is released from the solvent and resonance frequency is altered. The main purpose of this work is to demonstrate the ability of BARDS to assess differences in the wetting behaviour of tablet excipients (microcrystalline cellulose (MCC) and magnesium stearate (MgSt)) and a model drug (metoclopramide hydrochloride) as single component <span class="hlt">powders</span> and multi-component <span class="hlt">powder</span> blends. BARDS acoustic responses showed a prolonged release of gas for the <span class="hlt">powdered</span> blends with lubricant compared to un-lubricated blends. As the elimination of gas from the solvent was assumed to follow first order elimination kinetics, a compressible gas elimination rate constant was calculated from the log plots of the gas volume profiles. The gas elimination rate constant was used as a parameter to compare the release of gas from the <span class="hlt">powder</span> introduced to the solvent and hence the <span class="hlt">powder</span> wetting behavior. A lower gas elimination rate constant was measured for lubricated blends compared to non-lubricated blends, suggesting the prolonged <span class="hlt">hydration</span> of lubricated blends. Standard wetting techniques such as contact angle measurements and wetting <span class="hlt">time</span> analysis were also used to analyze the blends and confirmed differences in wetting behavior determined by BARDS. The study results demonstrate the capability of BARDS as a rapid, analytical tool to determine the wetting behavior of the pharmaceutical <span class="hlt">powder</span> blends and the potential of BARDS as a process analytical technology</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1039916','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1039916"><span><span class="hlt">Hydration</span> of gas-phase ytterbium ion complexes studied by experiment and theory</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.</p> <p>2011-02-11</p> <p><span class="hlt">Hydration</span> of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence <span class="hlt">time</span> in the trap. From the <span class="hlt">time</span> dependence of the <span class="hlt">hydration</span> steps, relative reaction rates were obtained. It was determined that the second <span class="hlt">hydration</span> was faster than both the first and third <span class="hlt">hydrations</span>, and the fourth <span class="hlt">hydration</span> was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing <span class="hlt">hydration</span> number. <span class="hlt">Hydration</span> energetics and <span class="hlt">hydrate</span> structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of <span class="hlt">hydration</span> of f-element ion complexes. The experimental observations - kinetics and extent of <span class="hlt">hydration</span> - are discussed in relationship to the computed structures and energetics of the <span class="hlt">hydrates</span>. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JApSp..82..175T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JApSp..82..175T"><span>Supramolecular Structures in Nanosilica/Miramistin <span class="hlt">Hydrated</span> Composite in a Hydrophobic Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turov, V. V.; Barvinchenko, V. N.; Lipkovska, N. A.; Fedyanina, T. V.</p> <p>2015-05-01</p> <p>The effect of a hydrophobic medium on the <span class="hlt">hydrated</span> properties of a <span class="hlt">powdered</span> nanocomposite based on the cationic surfactant miramistin and silica was studied using low-temperature PMR spectroscopy. The thermodynamic parameters of strongly and weakly bound water layers and the interfacial energy of water in pore cavities of the nanocomposite were determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26049527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26049527"><span>Some thermodynamical aspects of protein <span class="hlt">hydration</span> water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H Eugene; Chen, Sow-Hsin</p> <p>2015-06-07</p> <p>We study by means of nuclear magnetic resonance the self-diffusion of protein <span class="hlt">hydration</span> water at different <span class="hlt">hydration</span> levels across a large temperature range that includes the deeply supercooled regime. Starting with a single <span class="hlt">hydration</span> shell (h = 0.3), we consider different <span class="hlt">hydrations</span> up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein <span class="hlt">hydration</span> water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the <span class="hlt">hydration</span> level and (ii) the first <span class="hlt">hydration</span> shell remains liquid at all <span class="hlt">hydrations</span>, even at the lowest temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22415955','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22415955"><span>Some thermodynamical aspects of protein <span class="hlt">hydration</span> water</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H. Eugene; Chen, Sow-Hsin</p> <p>2015-06-07</p> <p>We study by means of nuclear magnetic resonance the self-diffusion of protein <span class="hlt">hydration</span> water at different <span class="hlt">hydration</span> levels across a large temperature range that includes the deeply supercooled regime. Starting with a single <span class="hlt">hydration</span> shell (h = 0.3), we consider different <span class="hlt">hydrations</span> up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein <span class="hlt">hydration</span> water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the <span class="hlt">hydration</span> level and (ii) the first <span class="hlt">hydration</span> shell remains liquid at all <span class="hlt">hydrations</span>, even at the lowest temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27076750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27076750"><span>A Study on the Chemical Compositions of the Yinqiaosan (Lonicerae and Forsythiae <span class="hlt">Powder</span>) at Different <span class="hlt">Time</span> of Later-decoction by Gas Chromatography Mass Spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shu, Yachun; Chen, Yajun; Qin, Kunming; Liu, Xiao; Cai, Baochang</p> <p>2016-01-01</p> <p>Yinqiaosan (Lonicerae and Forsythiae <span class="hlt">Powder</span>), as a famous prescription of Dr. Wu Jutong in Qing dynasty of China, has the effects of diaphoresis cooling, fire-purging, and detoxicaton. It is mainly used in the treatment of influenza, hand-foot-mouth disease, esophagitis, pneumonia, acute tonsillitis, mumps, and other viral infections. It is one of the widely used traditional Chinese medicine prescriptions with proven curative effects in clinical use. To research the material basis of Yinqiaosan decoction when decocting mint, herba schizonepetae in different length of later-decoction <span class="hlt">time</span>, to find the influence on volatile components of Yinqiaosan decoction decocted later in different length of <span class="hlt">time</span>, to lay the foundation to further clarify the after-decoction mechanism of Yinqiaosan, and the specification of Yinqiaosan decoction process. Gas chromatography mass spectrometry method is used to analyze the volatile components of Yinqiaosan decoction samples decocted for 0, 3, 5, 8, and 10 min. Later-decocting mint and herba schizonepetae at different <span class="hlt">time</span> when decocting Yinqiaosan had a significant influence on the volatile components of the solution. 54 different chemical components were identified: 25 were identified when later-decocting the sample for 3 min; 13 were identified when later-decocting the sample for 5 min; 11 were identified when later-decocting the sample for 8 min; 7 were identified when later-decocting the sample for 10 min; and 26 were identified when later-decocting the sample for 0 min. There were more volatile components in the sample after-decocted for 3 min. A total of 54 different chemical components were identified in different later-decocting solution samples. These components form the basis of the Yinqiaosan drug effect. The length of later-decoction <span class="hlt">time</span> of mint and herba schizonepetae was confirmed to be 3 min when decocting Yinqiaosan. Later-decocting mint and herba schizonepetae at different <span class="hlt">time</span> had a significant influence on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4809168','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4809168"><span>A Study on the Chemical Compositions of the Yinqiaosan (Lonicerae and Forsythiae <span class="hlt">Powder</span>) at Different <span class="hlt">Time</span> of Later-decoction by Gas Chromatography Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shu, Yachun; Chen, Yajun; Qin, Kunming; Liu, Xiao; Cai, Baochang</p> <p>2016-01-01</p> <p>Background: Yinqiaosan (Lonicerae and Forsythiae <span class="hlt">Powder</span>), as a famous prescription of Dr. Wu Jutong in Qing dynasty of China, has the effects of diaphoresis cooling, fire-purging, and detoxicaton. It is mainly used in the treatment of influenza, hand-foot-mouth disease, esophagitis, pneumonia, acute tonsillitis, mumps, and other viral infections. It is one of the widely used traditional Chinese medicine prescriptions with proven curative effects in clinical use. Objective: To research the material basis of Yinqiaosan decoction when decocting mint, herba schizonepetae in different length of later-decoction <span class="hlt">time</span>, to find the influence on volatile components of Yinqiaosan decoction decocted later in different length of <span class="hlt">time</span>, to lay the foundation to further clarify the after-decoction mechanism of Yinqiaosan, and the specification of Yinqiaosan decoction process. Materials and Methods: Gas chromatography mass spectrometry method is used to analyze the volatile components of Yinqiaosan decoction samples decocted for 0, 3, 5, 8, and 10 min. Results: Later-decocting mint and herba schizonepetae at different <span class="hlt">time</span> when decocting Yinqiaosan had a significant influence on the volatile components of the solution. 54 different chemical components were identified: 25 were identified when later-decocting the sample for 3 min; 13 were identified when later-decocting the sample for 5 min; 11 were identified when later-decocting the sample for 8 min; 7 were identified when later-decocting the sample for 10 min; and 26 were identified when later-decocting the sample for 0 min. There were more volatile components in the sample after-decocted for 3 min. A total of 54 different chemical components were identified in different later-decocting solution samples. These components form the basis of the Yinqiaosan drug effect. Conclusions: The length of later-decoction <span class="hlt">time</span> of mint and herba schizonepetae was confirmed to be 3 min when decocting Yinqiaosan. SUMMARY Later-decocting mint and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS31G..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS31G..01C"><span>Gas <span class="hlt">Hydrate</span> Petroleum System Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collett, T. S.</p> <p>2012-12-01</p> <p>In a gas <span class="hlt">hydrate</span> petroleum system, the individual factors that contribute to the formation of gas <span class="hlt">hydrate</span> accumulations, such as (1) gas <span class="hlt">hydrate</span> pressure-temperature stability conditions, (2) gas source, (3) gas migration, and (4) the growth of the gas <span class="hlt">hydrate</span> in suitable host sediment can identified and quantified. The study of know and inferred gas <span class="hlt">hydrate</span> accumulations reveal the occurrence of concentrated gas <span class="hlt">hydrate</span> is mostly controlled by the presence of fractures and/or coarser grained sediments. Field studies have concluded that <span class="hlt">hydrate</span> grows preferentially in coarse-grained sediments because lower capillary pressures in these sediments permit the migration of gas and nucleation of <span class="hlt">hydrate</span>. Due to the relatively distal nature of the deep marine geologic settings, the overall abundance of sand within the shallow geologic section is usually low. However, drilling projects in the offshore of Japan, Korea, and in the Gulf of Mexico has revealed the occurrence of significant <span class="hlt">hydrate</span>-bearing sand reservoirs. The 1999/2000 Japan Nankai Trough drilling confirmed occurrence of <span class="hlt">hydrate</span>-bearing sand-rich intervals (interpreted as turbidite fan deposits). Gas <span class="hlt">hydrate</span> was determined to fill the pore spaces in these deposits, reaching saturations up to 80% in some layers. A multi-well drilling program titled "METI Toaki-oki to Kumano-nada" also identified sand-rich reservoirs with pore-filling <span class="hlt">hydrate</span>. The recovered <span class="hlt">hydrate</span>-bearing sand layers were described as very-fine- to fine-grained turbidite sand layers measuring from several centimeters up to a meter thick. However, the gross thickness of the <span class="hlt">hydrate</span>-bearing sand layers were up to 50 m. In 2010, the Republic of Korea conducted the Second Ulleung Basin Gas <span class="hlt">Hydrate</span> (UBGH2) Drilling Expedition. Seismic data clearly showed the development of a thick, potential basin wide, sedimentary sections characterized by mostly debris flows. The downhole LWD logs and core data from Site UBGH2-5 reveal that each debris flows is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P53A2161H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P53A2161H"><span>Diurnally-Varying Lunar <span class="hlt">Hydration</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hendrix, A. R.; Hurley, D.; Retherford, K. D.; Mandt, K.; Greathouse, T. K.; Farrell, W. M.; Vilas, F.</p> <p>2016-12-01</p> <p>Dayside, non-polar lunar <span class="hlt">hydration</span> signatures have been observed by a handful of instruments and present insights into the lunar water cycle. In this study, we utilize the unique measurements from the current Lunar Reconnaissance Orbiter (LRO) mission to study the phenomenon of diurnally-varying dayside lunar <span class="hlt">hydration</span>. The Lyman Alpha Mapping Project (LAMP) onboard LRO senses a strong far-ultraviolet water absorption edge indicating <span class="hlt">hydration</span> in small abundances in the permanently shadowed regions as well as on the lunar dayside. We report on diurnal variability in <span class="hlt">hydration</span> in different terrain types. We investigate the importance of different sources of <span class="hlt">hydration</span>, including solar wind bombardment and meteoroid bombardment, by observing trends during magnetotail and meteor stream crossings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T42B..03B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T42B..03B"><span>Colorado Plateau Uplift Through Deep Crustal <span class="hlt">Hydration</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butcher, L. A.; Mahan, K. H.; Jones, C. H.; Farmer, G.</p> <p>2013-12-01</p> <p>The conventional view of plate tectonics restricts deformation to plate boundaries and does not account for regionally elevated topography in continental interiors. Thermal, mechanical or chemical alteration of ancient continental lithosphere is a mechanism sometimes invoked to explain intracratonic uplift in the western U.S. although the <span class="hlt">timing</span>, extent and effects of this modification are poorly understood. Here we present new petrological and in situ geochronological data for a <span class="hlt">hydrated</span> deep crustal xenolith from the Colorado Plateau and investigate the effects of deep crustal <span class="hlt">hydration</span> on topography. Two distinct mineral assemblages recorded in a garnet biotite schist xenolith from the Navajo Volcanic Field, Four Corners region document <span class="hlt">hydration</span> subsequent to peak metamorphism in the deep crust whereby the primary metamorphic assemblage (Gt + Bt + Ms + Pl + Kfs + Qtz) is variably replaced by a lower-density, <span class="hlt">hydrated</span> assemblage (Ab + Ph + Cc + Rt). Results from forward petrological modeling constrain <span class="hlt">hydration</span> at ≥ 20 km (0.65 GPa, 450 °C) prior to exhumation in the ˜20 Ma volcanic host. In situ Th/Pb dating of secondary monazite grains spatially associated with fluid-related plagioclase and allanite breakdown reveals a significant majority of Late Cretaceous dates from 91 to 58 Ma. These dates are interpreted to reflect a finite period of deep crustal <span class="hlt">hydration</span>, possibly by fluids sourced from a shallowly subducting Farallon slab. Xenolith data additionally supports crustal <span class="hlt">hydration</span> as a mechanism for producing regionally elevated topography. Fluid-related reactions in the deep crust may lead to a net density decrease as low-density hydrous phases (e.g. Ms + Amp + Cc) replace high-density, anhydrous minerals (e.g. Gt + Fsp + Opx + Cpx) abundant in high-pressure, high-temperature assemblages preserved in Proterozoic North American lithosphere. If these reactions are sufficiently pervasive and widespread, reductions in lower crustal density would provide a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030352','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030352"><span>Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, J.Y.; Santamarina, J.C.; Ruppel, C.</p> <p>2008-01-01</p> <p>Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on sediments recovered during drilling in the northern Gulf of Mexico at the Atwater Valley and Keathley Canyon sites as part of the 2005 Chevron Joint Industry Project on Methane <span class="hlt">Hydrates</span>. The tested specimens include both unremolded specimens (as recovered from the original core liner) and remolded sediments both without gas <span class="hlt">hydrate</span> and with pore fluid exchanged to attain 100% synthetic (tetrahydrofuran) <span class="hlt">hydrate</span> saturation at any stage of loading. Test results demonstrate the extent to which the electromagnetic and mechanical properties of <span class="hlt">hydrate</span>-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, <span class="hlt">hydrate</span> saturation, fabric, ionic concentration of the pore fluid, and temperature. We also show how permittivity and electrical conductivity data can be used to estimate the evolution of <span class="hlt">hydrate</span> volume fraction during formation. The gradual evolution of geophysical properties during <span class="hlt">hydrate</span> formation probably reflects the slow increase in ionic concentration in the pore fluid due to ion exclusion in closed systems and the gradual decrease in average pore size in which the <span class="hlt">hydrate</span> forms. During <span class="hlt">hydrate</span> formation, the increase in S-wave velocity is delayed with respect to the decrease in permittivity, consistent with <span class="hlt">hydrate</span> formation on mineral surfaces and subsequent crystal growth toward the pore space. No significant decementation/debonding occurred in 100% THF <span class="hlt">hydrate</span>-saturated sediments during unloading, hence the probability of sampling <span class="hlt">hydrate</span>-bearing sediments without disturbing the original sediment fabric is greatest for samples in which the gas <span class="hlt">hydrate</span> is primarily responsible for maintaining the sediment fabric and for which the <span class="hlt">time</span> between core retrieval and restoration of in situ effective stress in the laboratory is minimized. In evaluating the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015LTP....41..429D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015LTP....41..429D"><span>Physical modeling of the formation of clathrate <span class="hlt">hydrates</span> of methane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drobyshev, A.; Aldiyarov, A.; Kurnosov, V.; Katpaeva, K.; Korshikov, E.; Sokolov, D.; Shinbayeva, A.; Timchenko, A.</p> <p>2015-06-01</p> <p>Nowadays natural gas <span class="hlt">hydrates</span> attract special attention as a possible source of fossil fuel. According to various estimates, the reserves of hydrocarbons in <span class="hlt">hydrates</span> exceed considerably explored reserves of natural gas. Due to the clathrate structure the unit volume of the gas <span class="hlt">hydrate</span> can contain up to 160-180 volumes of pure gas. In recent years interest to a problem of gas <span class="hlt">hydrates</span> has considerably increased. Such changes are connected with the progress in searches of the alternative sources of hydrocarbonic raw materials in countries that do not possess the resources of energy carriers. Thus gas <span class="hlt">hydrates</span> are nonconventional sources of the hydrocarbonic raw materials which can be developed in the near future. At the same <span class="hlt">time</span>, mechanisms of methane clathrate <span class="hlt">hydrates</span> formations have not reached an advanced level, their thermophysical and mechanical properties have not been investigated profoundly. Thereby our experimental modeling of the processes of formation of methane clathrate <span class="hlt">hydrates</span> in water cryomatrix prepared by co-condensation from the gas phase onto a cooled substrate was carried out over the range of condensation temperatures 12-60 K and pressures 10-4-10-6 Torr. In our experiments the concentration of methane in water varied in the range of 5%-90%. The thickness deposited films was 30-60 μm. The vibrational spectra of two-component thin films of CH4 + H2O condensates were measured and analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27222203','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27222203"><span>Effects of ensembles on methane <span class="hlt">hydrate</span> nucleation kinetics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Zhengcai; Liu, Chan-Juan; Walsh, Matthew R; Guo, Guang-Jun</p> <p>2016-06-21</p> <p>By performing molecular dynamics simulations to form a <span class="hlt">hydrate</span> with a methane nano-bubble in liquid water at 250 K and 50 MPa, we report how different ensembles, such as the NPT, NVT, and NVE ensembles, affect the nucleation kinetics of the methane <span class="hlt">hydrate</span>. The nucleation trajectories are monitored using the face-saturated incomplete cage analysis (FSICA) and the mutually coordinated guest (MCG) order parameter (OP). The nucleation rate and the critical nucleus are obtained using the mean first-passage <span class="hlt">time</span> (MFPT) method based on the FS cages and the MCG-1 OPs, respectively. The fitting results of MFPT show that <span class="hlt">hydrate</span> nucleation and growth are coupled together, consistent with the cage adsorption hypothesis which emphasizes that the cage adsorption of methane is a mechanism for both <span class="hlt">hydrate</span> nucleation and growth. For the three different ensembles, the <span class="hlt">hydrate</span> nucleation rate is quantitatively ordered as follows: NPT > NVT > NVE, while the sequence of <span class="hlt">hydrate</span> crystallinity is exactly reversed. However, the largest size of the critical nucleus appears in the NVT ensemble, rather than in the NVE ensemble. These results are helpful for choosing a suitable ensemble when to study <span class="hlt">hydrate</span> formation via computer simulations, and emphasize the importance of the order degree of the critical nucleus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24266729','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24266729"><span>Adhesion force between cyclopentane <span class="hlt">hydrate</span> and mineral surfaces.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aman, Zachary M; Leith, William J; Grasso, Giovanny A; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A</p> <p>2013-12-17</p> <p>Clathrate <span class="hlt">hydrate</span> adhesion forces play a critical role in describing aggregation and deposition behavior in conventional energy production and transportation. This manuscript uses a unique micromechanical force apparatus to measure the adhesion force between cyclopentane <span class="hlt">hydrate</span> and heterogeneous quartz and calcite substrates. The latter substrates represent models for coproduced sand and scale often present during conventional energy production and transportation. Micromechanical adhesion force data indicate that clathrate <span class="hlt">hydrate</span> adhesive forces are 5-10× larger for calcite and quartz minerals than stainless steel. Adhesive forces further increased by 3-15× when increasing surface contact <span class="hlt">time</span> from 10 to 30 s. In some cases, liquid water from within the <span class="hlt">hydrate</span> shell contacted the mineral surface and rapidly converted to clathrate <span class="hlt">hydrate</span>. Further measurements on mineral surfaces with physical control of surface roughness showed a nonlinear dependence of water wetting angle on surface roughness. Existing adhesive force theory correctly predicted the dependence of clathrate <span class="hlt">hydrate</span> adhesive force on calcite wettability, but did not accurately capture the dependence on quartz wettability. This comparison suggests that the substrate surface may not be inert, and may contribute positively to the strength of the capillary bridge formed between <span class="hlt">hydrate</span> particles and solid surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873834','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873834"><span>Precision <span class="hlt">powder</span> feeder</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Schlienger, M. Eric; Schmale, David T.; Oliver, Michael S.</p> <p>2001-07-10</p> <p>A new class of precision <span class="hlt">powder</span> feeders is disclosed. These feeders provide a precision flow of a wide range of <span class="hlt">powdered</span> materials, while remaining robust against jamming or damage. These feeders can be precisely controlled by feedback mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090042936','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090042936"><span>Composite <span class="hlt">powder</span> particles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, Donald S. (Inventor); MacDowell, Louis G. (Inventor)</p> <p>2009-01-01</p> <p>A liquid coating composition including a coating vehicle and composite <span class="hlt">powder</span> particles disposed within the coating vehicle. Each composite <span class="hlt">powder</span> particle may include a magnesium component, a zinc component, and an indium component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.7044M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.7044M"><span>The connection between natural gas <span class="hlt">hydrate</span> and bottom-simulating reflectors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Majumdar, Urmi; Cook, Ann E.; Shedd, William; Frye, Matthew</p> <p>2016-07-01</p> <p>Bottom-simulating reflectors (BSRs) on marine seismic data are commonly used to identify the presence of natural gas <span class="hlt">hydrate</span> in marine sediments, although the exact relationship between gas <span class="hlt">hydrate</span> and BSRs is undefined. To clarify this relationship we compile a data set of probable gas <span class="hlt">hydrate</span> occurrence as appraised from well logs of 788 industry wells in the northern Gulf of Mexico. We combine the well log data set with a data set of BSR distribution in the same area identified from 3-D seismic data. We find that a BSR increases the chances of finding gas <span class="hlt">hydrate</span> by 2.6 <span class="hlt">times</span> as opposed to drilling outside a BSR and that the wells within a BSR also contain thicker and higher resistivity <span class="hlt">hydrate</span> accumulations. Even so, over half of the wells drilled through BSRs have no detectable gas <span class="hlt">hydrate</span> accumulations and gas <span class="hlt">hydrate</span> occurrences and BSRs do not coincide in most cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1011025','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1011025"><span>Dynamics of Biological Macromolecules: Not a Simple Slaving by <span class="hlt">Hydration</span> Water</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kisliuk, Alexander; Sokolov, Alexei P; Mamontov, Eugene; Khodadadi, S; Roh, J H; Tyagi, M.; Briber, R M; Woodson, S.A.</p> <p>2010-01-01</p> <p>We studied the dynamics of <span class="hlt">hydrated</span> tRNA using neutron and dielectric spectroscopy techniques. A comparison of our results with earlier data reveals that the dynamics of <span class="hlt">hydrated</span> tRNA is slower and varies more strongly with temperature than the dynamics of <span class="hlt">hydrated</span> proteins. At the same <span class="hlt">time</span>, tRNA appears to have faster dynamics than DNA. We demonstrate that a similar difference appears in the dynamics of <span class="hlt">hydration</span> water for these biomolecules. The results and analysis contradict the traditional view of slaved dynamics, which assumes that the dynamics of biological macromolecules just follows the dynamics of <span class="hlt">hydration</span> water. Our results demonstrate that the dynamics of biological macromolecules and their <span class="hlt">hydration</span> water depends strongly on the chemical and three-dimensional structures of the biomolecules. We conclude that the whole concept of slaving dynamics should be reconsidered, and that the mutual influence of biomolecules and their <span class="hlt">hydration</span> water must be taken into account.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2849066','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2849066"><span>Dynamics of Biological Macromolecules: Not a Simple Slaving by <span class="hlt">Hydration</span> Water</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Khodadadi, S.; Roh, J.H.; Kisliuk, A.; Mamontov, E.; Tyagi, M.; Woodson, S.A.; Briber, R.M.; Sokolov, A.P.</p> <p>2010-01-01</p> <p>We studied the dynamics of <span class="hlt">hydrated</span> tRNA using neutron and dielectric spectroscopy techniques. A comparison of our results with earlier data reveals that the dynamics of <span class="hlt">hydrated</span> tRNA is slower and varies more strongly with temperature than the dynamics of <span class="hlt">hydrated</span> proteins. At the same <span class="hlt">time</span>, tRNA appears to have faster dynamics than DNA. We demonstrate that a similar difference appears in the dynamics of <span class="hlt">hydration</span> water for these biomolecules. The results and analysis contradict the traditional view of slaved dynamics, which assumes that the dynamics of biological macromolecules just follows the dynamics of <span class="hlt">hydration</span> water. Our results demonstrate that the dynamics of biological macromolecules and their <span class="hlt">hydration</span> water depends strongly on the chemical and three-dimensional structures of the biomolecules. We conclude that the whole concept of slaving dynamics should be reconsidered, and that the mutual influence of biomolecules and their <span class="hlt">hydration</span> water must be taken into account. PMID:20371332</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...710952P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...710952P"><span>Understanding silicate <span class="hlt">hydration</span> from quantitative analyses of <span class="hlt">hydrating</span> tricalcium silicates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; D'Espinose de Lacaillerie, Jean-Baptiste</p> <p>2016-03-01</p> <p>Silicate <span class="hlt">hydration</span> is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement <span class="hlt">hydration</span>. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-<span class="hlt">hydrates</span> (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the <span class="hlt">hydration</span> process in terms of transient local molecular composition, extent of silicate <span class="hlt">hydration</span> and polymerization. This provides insights on the relative influence of surface hydroxylation and <span class="hlt">hydrate</span> precipitation on the <span class="hlt">hydration</span> rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820784','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820784"><span>Understanding silicate <span class="hlt">hydration</span> from quantitative analyses of <span class="hlt">hydrating</span> tricalcium silicates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; d'Espinose de Lacaillerie, Jean-Baptiste</p> <p>2016-01-01</p> <p>Silicate <span class="hlt">hydration</span> is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement <span class="hlt">hydration</span>. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-<span class="hlt">hydrates</span> (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the <span class="hlt">hydration</span> process in terms of transient local molecular composition, extent of silicate <span class="hlt">hydration</span> and polymerization. This provides insights on the relative influence of surface hydroxylation and <span class="hlt">hydrate</span> precipitation on the <span class="hlt">hydration</span> rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1532S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1532S"><span>Detection and Appraisal of Gas <span class="hlt">Hydrates</span>: Indian Scenario</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sain, K.</p> <p>2009-04-01</p> <p>Gas <span class="hlt">hydrates</span>, found in shallow sediments of permafrost and outer continental margins, are crystalline form of methane and water. The carbon within global gas <span class="hlt">hydrates</span> is estimated two <span class="hlt">times</span> the carbon contained in world-wide fossil fuels. It is also predicted that 15% recovery of gas <span class="hlt">hydrates</span> can meet the global energy requirement for the next 200 years. Several parameters like bathymetry, seafloor temperature, sediment thickness, rate of sedimentation and total organic carbon content indicate very good prospect of gas <span class="hlt">hydrates</span> in the vast offshore regions of India. Methane stored in the form of gas <span class="hlt">hydrates</span> within the Indian exclusive economic zone is estimated to be few hundred <span class="hlt">times</span> the country's conventional gas reserve. India produces less than one-third of her oil requirement and gas <span class="hlt">hydrates</span> provide great hopes as a viable source of energy in the 21st century. Thus identification and quantitative assessment of gas <span class="hlt">hydrates</span> are very important. By scrutiny and reanalysis of available surface seismic data, signatures of gas <span class="hlt">hydrates</span> have been found out in the Kerala-Konkan and Saurashtra basins in the western margin, and Krishna-Godavari, Mahanadi and Andaman regions in the eastern margin of India by mapping the bottom simulating reflector or BSR based on its characteristic features. In fact, the coring and drilling in 2006 by the Indian National Gas <span class="hlt">Hydrate</span> Program have established the ground truth in the eastern margin. It has become all the more important now to identify further prospective regions with or without BSR; demarcate the lateral/areal extent of gas <span class="hlt">hydrate</span>-bearing sediments and evaluate their resource potential in both margins of India. We have developed various approaches based on seismic traveltime tomography; waveform inversion; amplitude versus offset (AVO) modeling; AVO attributes; seismic attributes and rock physics modeling for the detection, delineation and quantification of gas-<span class="hlt">hydrates</span>. The blanking, reflection strength, instantaneous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5398927','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5398927"><span>Perspective: Structure and ultrafast dynamics of biomolecular <span class="hlt">hydration</span> shells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Laage, Damien; Elsaesser, Thomas; Hynes, James T.</p> <p>2017-01-01</p> <p>The structure and function of biomolecules can be strongly influenced by their <span class="hlt">hydration</span> shells. A key challenge is thus to determine the extent to which these shells differ from bulk water, since the structural fluctuations and molecular excitations of <span class="hlt">hydrating</span> water molecules within these shells can cover a broad range in both space and <span class="hlt">time</span>. Recent progress in theory, molecular dynamics simulations, and ultrafast vibrational spectroscopy has led to new and detailed insight into the fluctuations of water structure, elementary water motions, and electric fields at <span class="hlt">hydrated</span> biointerfaces. Here, we discuss some central aspects of these advances, focusing on elementary molecular mechanisms and processes of <span class="hlt">hydration</span> on a femto- to picosecond <span class="hlt">time</span> scale, with some special attention given to several issues subject to debate. PMID:28470026</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMOS42B..02K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMOS42B..02K"><span>Laboratory and Seafloor Experiments with Hydrocarbon Clathrate <span class="hlt">Hydrates</span>: A Review with Potential Applications to <span class="hlt">Hydrates</span> in Nature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirby, S. H.; Stern, L. A.; Brewer, P.; Circone, S.; Durham, W. B.</p> <p>2003-12-01</p> <p>The in-situ chemical composition, structure, and textural positions of clathrate <span class="hlt">hydrates</span> within sediments, and their effects on the properties of their host sediments are important features that are rarely, if ever, determined directly. All hydrocarbon clathrate <span class="hlt">hydrates</span> retrieved from their natural environments for study in the lab at atmospheric pressure have been to some degree altered and/or partially decomposed during transit and handling. Thus interpretation of their structures, textures and properties is not always straightforward. Laboratory and seafloor experiments on synthetic hydrocarbon <span class="hlt">hydrates</span> and aggregates with sediment are useful for aiding the interpretation of retrieved materials. Here we describe such exploratory efforts at the USGS, MBARI and LLNL: (1) Rock-physics theory and measurements of the physical properties of multi-phase granular materials in general indicate that the textural position (conformation) of <span class="hlt">hydrates</span> in the pore space of sediment dictate the quantitative effects of <span class="hlt">hydrates</span> on sediment properties. Our ice-to-<span class="hlt">hydrate</span> synthesis method permits us to make synthetic sediment/<span class="hlt">hydrate</span> aggregates with known conformation as well as measure accurately their bulk properties and test the rock-physics theories. Such tests currently seem infeasible using natural samples. (2) Such synthetic samples with known <span class="hlt">hydrate</span> characteristics and properties can be subjected to known P-T-<span class="hlt">time</span> pathways that simulate the retrieval pathways of natural samples. The effects of the retrieval process can be evaluated by comparing the starting <span class="hlt">hydrate</span> characteristics and properties with those of the simulated "retrieved" material. Optical-cell experiments can be potentially useful in evaluating the textural effects of retrieval by direct observation. (3) The governing physical chemistry of our ice-to-<span class="hlt">hydrate</span> synthesis method is probably different from that in natural environments. We have found, however, that exposure of lab-made samples to the seafloor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/348922','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/348922"><span>Aluminum <span class="hlt">powder</span> metallurgy processing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Flumerfelt, J.F.</p> <p>1999-02-12</p> <p>The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum <span class="hlt">powder</span> characteristics, and the consolidation methodology required to make components from aluminum <span class="hlt">powder</span>. The hypothesis was tested with pure aluminum <span class="hlt">powders</span> produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum <span class="hlt">powders</span> with the commercial aluminum <span class="hlt">powders</span> showed the former to exhibit superior <span class="hlt">powder</span> characteristics. The <span class="hlt">powders</span> were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum <span class="hlt">powders</span> were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum <span class="hlt">powders</span> were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum <span class="hlt">powder</span>. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization <span class="hlt">powder</span> oxidation. The pure aluminum <span class="hlt">powders</span> were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum <span class="hlt">powder</span> and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum <span class="hlt">powders</span> can form sintering necks between contacting <span class="hlt">powder</span> particles, unlike the total resistance to sintering of commercial air atomization aluminum <span class="hlt">powder</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...623220X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...623220X"><span>Pectin as an Extraordinary Natural Kinetic <span class="hlt">Hydrate</span> Inhibitor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Shurui; Fan, Shuanshi; Fang, Songtian; Lang, Xuemei; Wang, Yanhong; Chen, Jun</p> <p>2016-03-01</p> <p>Pectin as a novel natural kinetic <span class="hlt">hydrate</span> inhibitor, expected to be eco-friendly and sufficiently biodegradable, was studied in this paper. The novel crystal growth inhibition (CGI) and standard induction <span class="hlt">time</span> methods were used to evaluate its effect as <span class="hlt">hydrate</span> inhibitor. It could successfully inhibit methane <span class="hlt">hydrate</span> formation at subcooling temperature up to 12.5 °C and dramatically slowed the <span class="hlt">hydrate</span> crystal growth. The dosage of pectin decreased by 66% and effective <span class="hlt">time</span> extended 10 <span class="hlt">times</span> than typical kinetic inhibitor. Besides, its maximum growth rate was no more than 2.0%/h, which was far less than 5.5%/h of growth rate for PVCap at the same dosage. The most prominent feature was that it totally inhibited methane <span class="hlt">hydrate</span> crystal rapid growth when <span class="hlt">hydrate</span> crystalline occurred. Moreover, in terms of typical natural inhibitors, the inhibition activity of pectin increased 10.0-fold in induction <span class="hlt">time</span> and 2.5-fold in subcooling temperature. The extraordinary inhibition activity is closely related to its hydrogen bonding interaction with water molecules and the hydrophilic structure. Finally, the biodegradability and economical efficiency of pectin were also taken into consideration. The results showed the biodegradability improved 75.0% and the cost reduced by more than 73.3% compared to typical commercial kinetic inhibitors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4800399','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4800399"><span>Pectin as an Extraordinary Natural Kinetic <span class="hlt">Hydrate</span> Inhibitor</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Shurui; Fan, Shuanshi; Fang, Songtian; Lang, Xuemei; Wang, Yanhong; Chen, Jun</p> <p>2016-01-01</p> <p>Pectin as a novel natural kinetic <span class="hlt">hydrate</span> inhibitor, expected to be eco-friendly and sufficiently biodegradable, was studied in this paper. The novel crystal growth inhibition (CGI) and standard induction <span class="hlt">time</span> methods were used to evaluate its effect as <span class="hlt">hydrate</span> inhibitor. It could successfully inhibit methane <span class="hlt">hydrate</span> formation at subcooling temperature up to 12.5 °C and dramatically slowed the <span class="hlt">hydrate</span> crystal growth. The dosage of pectin decreased by 66% and effective <span class="hlt">time</span> extended 10 <span class="hlt">times</span> than typical kinetic inhibitor. Besides, its maximum growth rate was no more than 2.0%/h, which was far less than 5.5%/h of growth rate for PVCap at the same dosage. The most prominent feature was that it totally inhibited methane <span class="hlt">hydrate</span> crystal rapid growth when <span class="hlt">hydrate</span> crystalline occurred. Moreover, in terms of typical natural inhibitors, the inhibition activity of pectin increased 10.0-fold in induction <span class="hlt">time</span> and 2.5-fold in subcooling temperature. The extraordinary inhibition activity is closely related to its hydrogen bonding interaction with water molecules and the hydrophilic structure. Finally, the biodegradability and economical efficiency of pectin were also taken into consideration. The results showed the biodegradability improved 75.0% and the cost reduced by more than 73.3% compared to typical commercial kinetic inhibitors. PMID:26996773</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26996773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26996773"><span>Pectin as an Extraordinary Natural Kinetic <span class="hlt">Hydrate</span> Inhibitor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Shurui; Fan, Shuanshi; Fang, Songtian; Lang, Xuemei; Wang, Yanhong; Chen, Jun</p> <p>2016-03-21</p> <p>Pectin as a novel natural kinetic <span class="hlt">hydrate</span> inhibitor, expected to be eco-friendly and sufficiently biodegradable, was studied in this paper. The novel crystal growth inhibition (CGI) and standard induction <span class="hlt">time</span> methods were used to evaluate its effect as <span class="hlt">hydrate</span> inhibitor. It could successfully inhibit methane <span class="hlt">hydrate</span> formation at subcooling temperature up to 12.5 °C and dramatically slowed the <span class="hlt">hydrate</span> crystal growth. The dosage of pectin decreased by 66% and effective <span class="hlt">time</span> extended 10 <span class="hlt">times</span> than typical kinetic inhibitor. Besides, its maximum growth rate was no more than 2.0%/h, which was far less than 5.5%/h of growth rate for PVCap at the same dosage. The most prominent feature was that it totally inhibited methane <span class="hlt">hydrate</span> crystal rapid growth when <span class="hlt">hydrate</span> crystalline occurred. Moreover, in terms of typical natural inhibitors, the inhibition activity of pectin increased 10.0-fold in induction <span class="hlt">time</span> and 2.5-fold in subcooling temperature. The extraordinary inhibition activity is closely related to its hydrogen bonding interaction with water molecules and the hydrophilic structure. Finally, the biodegradability and economical efficiency of pectin were also taken into consideration. The results showed the biodegradability improved 75.0% and the cost reduced by more than 73.3% compared to typical commercial kinetic inhibitors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034343','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034343"><span>Methane <span class="hlt">hydrate</span> synthesis from ice: Influence of pressurization and ethanol on optimizing formation rates and <span class="hlt">hydrate</span> yield</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Chen, Po-Chun.; Huang, Wuu-Liang; Stern, Laura A.</p> <p>2010-01-01</p> <p>Polycrystalline methane gas <span class="hlt">hydrate</span> (MGH) was synthesized using an ice-seeding method to investigate the influence of pressurization and ethanol on the <span class="hlt">hydrate</span> formation rate and gas yield of the resulting samples. When the reactor is pressurized with CH4 gas without external heating, methane <span class="hlt">hydrate</span> can be formed from ice grains with yields up to 25% under otherwise static conditions. The rapid temperature rise caused by pressurization partially melts the granular ice, which reacts with methane to form <span class="hlt">hydrate</span> rinds around the ice grains. The heat generated by the exothermic reaction of methane <span class="hlt">hydrate</span> formation buffers the sample temperature near the melting point of ice for enough <span class="hlt">time</span> to allow for continuous <span class="hlt">hydrate</span> growth at high rates. Surprisingly, faster rates and higher yields of methane <span class="hlt">hydrate</span> were found in runs with lower initial temperatures, slower rates of pressurization, higher porosity of the granular ice samples, or mixtures with sediments. The addition of ethanol also dramatically enhanced the formation of polycrystalline MGH. This study demonstrates that polycrystalline MGH with varied physical properties suitable for different laboratory tests can be manufactured by controlling synthesis procedures or parameters. Subsequent dissociation experiments using a gas collection apparatus and flowmeter confirmed high methane saturation (CH 4·2O, with n = 5.82 ± 0.03) in the MGH. Dissociation rates of the various samples synthesized at diverse conditions may be fitted to different rate laws, including zero and first order.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28614817','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28614817"><span>Shifting Focus: From <span class="hlt">Hydration</span> for Performance to <span class="hlt">Hydration</span> for Health.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perrier, Erica T</p> <p>2017-01-01</p> <p>Over the past 10 years, literature on <span class="hlt">hydration</span> biomarkers has evolved considerably - from (de)<span class="hlt">hydration</span> assessment towards a more global definition of biomarkers of <span class="hlt">hydration</span> in daily life. This shift in thinking about <span class="hlt">hydration</span> markers was largely driven by investigating the differences that existed between otherwise healthy individuals whose habitual, ad-libitum drinking habits differ, and by identifying physiological changes in low-volume drinkers who subsequently increase their water intake. Aside from obvious differences in urinary volume and concentration, a growing body of evidence is emerging that links differences in fluid intake with small, but biologically significant, differences in vasopressin (copeptin), glomerular filtration rate, and markers of metabolic dysfunction or disease. Taken together, these pieces of the puzzle begin to form a picture of how much water intake should be considered adequate for health, and represent a shifting focus from <span class="hlt">hydration</span> for performance, toward <span class="hlt">hydration</span> for health outcomes. This narrative review outlines the key areas of research in which the global <span class="hlt">hydration</span> process - including water intake, urinary <span class="hlt">hydration</span> markers, and vasopressin - has been associated with health outcomes, focusing on kidney and metabolic endpoints. It will also provide a commentary on how various <span class="hlt">hydration</span> biomarkers may be used in <span class="hlt">hydration</span> for health assessment. Finally, if adequate water intake can play a role in maintaining health, how might we tell if we are drinking enough? Urine output is easily measured, and can take into account differences in daily physical activity, climate, dietary solute load, and other factors that influence daily water needs. Today, targets have been proposed for urine osmolality, specific gravity, and color that may be used by researchers, clinicians, and individuals as simple indicators of optimal <span class="hlt">hydration</span>. However, there remain a large number of incomplete or unanswered research questions regarding the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22395922','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22395922"><span><span class="hlt">Hydration</span> mechanisms of two polymorphs of synthetic ye'elimite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cuesta, A.; Álvarez-Pinazo, G.; Peral, I.; Aranda, M.A.G.; De la Torre, A.G.</p> <p>2014-09-15</p> <p>Ye'elimite is the main phase in calcium sulfoaluminate cements and also a key phase in sulfobelite cements. However, its <span class="hlt">hydration</span> mechanism is not well understood. Here we reported new data on the <span class="hlt">hydration</span> behavior of ye'elimite using synchrotron and laboratory <span class="hlt">powder</span> diffraction coupled to the Rietveld methodology. Both internal and external standard methodologies have been used to determine the overall amorphous contents. We have addressed the standard variables: water-to-ye'elimite ratio and additional sulfate sources of different solubilities. Moreover, we report a deep study of the role of the polymorphism of pure ye'elimites. The <span class="hlt">hydration</span> behavior of orthorhombic stoichiometric and pseudo-cubic solid-solution ye'elimites is discussed. In the absence of additional sulfate sources, stoichiometric-ye'elimite reacts slower than solid-solution-ye'elimite, and AFm-type phases are the main <span class="hlt">hydrated</span> crystalline phases, as expected. Moreover, solid-solution-ye'elimite produces higher amounts of ettringite than stoichiometric-ye'elimite. However, in the presence of additional sulfates, stoichiometric-ye'elimite reacts faster than solid-solution-ye'elimite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1008673','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1008673"><span>Class H Oil Well Cement <span class="hlt">Hydration</span> at Elevated Temperatures in the Presence of Retarding Agents: An In Situ High-Energy X-ray Diffraction Study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jupe, Andrew C.; Wilkinson, Angus P.; Luke, Karen; Funkhouser, Gary P.</p> <p>2008-07-08</p> <p>In situ <span class="hlt">powder</span> X-ray diffraction was used to examine the <span class="hlt">hydration</span> of API Class H cement slurries, with a water-to-cement ratio of 0.394, at 66, 93, 121, and 177 C under autogenous pressure in the presence of varying amounts of the additives tartaric acid, modified lignosulfonate, and AMPS (2-acrylamido-2-methylpropanesulfonic acid) copolymer. All of these retarding agents inhibited the <span class="hlt">hydration</span> of crystalline C{sub 3}S (Ca{sub 3}SiO{sub 5}), but other modes of action were also apparent. The formation of ettringite was suppressed when tartaric acid was used by itself or in combination with other additives. Changes in the <span class="hlt">hydration</span> of C{sub 3}S vs <span class="hlt">time</span> could not be correlated in a simple way with the observed pumping <span class="hlt">times</span> for the cement slurries. The largest changes in pumping <span class="hlt">time</span> as a function of temperature occurred in a temperature interval where ettringite/monosulfate decomposes and crystalline hydrogarnet starts to be formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27466974','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27466974"><span>Kinetics of bread crumb <span class="hlt">hydration</span> as related to porous microstructure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mathieu, Vincent; Monnet, Anne-Flore; Jourdren, Solenne; Panouillé, Maud; Chappard, Christine; Souchon, Isabelle</p> <p>2016-08-10</p> <p>During oral processing and throughout the digestion process, <span class="hlt">hydration</span> mechanisms have a key influence on the functional properties of food. This is the case with bread, for which <span class="hlt">hydration</span> may affect the kinetics of starch hydrolysis as well as taste, aroma and texture perceptions. In this context, the aim of the present study is to understand how crumb porous micro-architecture impacts <span class="hlt">hydration</span> kinetics. Four types of French baguettes were considered, varying in structure and/or compositions. An experimental set-up was developed for the real-<span class="hlt">time</span> measurement of water uptake in crumb samples. Mathematical models were then fitted to extract quantitative parameters of use for the description and the understanding of experimental observations. Finally, bread crumb samples were analyzed before and after <span class="hlt">hydration</span> through X-ray micro-computed tomography for the assessment of crumb micro-architectural properties. Distinct <span class="hlt">hydration</span> behaviors were observed for the four types of bread. Higher <span class="hlt">hydration</span> rates and capacities were reported for industrial baguettes (highest porosity) compared to denser semi-industrial, whole wheat and traditional baguettes. However, crumb porosity alone is not sufficient to predict <span class="hlt">hydration</span> behavior. This study made it possible to point out the importance of capillary action in crumb <span class="hlt">hydration</span> mechanisms, with a strong role of cells with diameters of 2 mm and below. The high density of these small cells generates high interconnection probabilities that may have an impact both on crumb <span class="hlt">hydration</span> duration and capacity. As a consequence, accounting for microstructural features resulting from bread formulation may provide useful leverages for the control of functional properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17.3717Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17.3717Y"><span>Synchrotron X-ray computed microtomography study on gas <span class="hlt">hydrate</span> decomposition in a sedimentary matrix</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Lei; Falenty, Andrzej; Chaouachi, Marwen; Haberthür, David; Kuhs, Werner F.</p> <p>2016-09-01</p> <p>In-situ synchrotron X-ray computed microtomography with sub-micrometer voxel size was used to study the decomposition of gas <span class="hlt">hydrates</span> in a sedimentary matrix. Xenon-<span class="hlt">hydrate</span> was used instead of methane <span class="hlt">hydrate</span> to enhance the absorption contrast. The microstructural features of the decomposition process were elucidated indicating that the decomposition starts at the <span class="hlt">hydrate</span>-gas interface; it does not proceed at the contacts with quartz grains. Melt water accumulates at retreating <span class="hlt">hydrate</span> surface. The decomposition is not homogeneous and the decomposition rates depend on the distance of the <span class="hlt">hydrate</span> surface to the gas phase indicating a diffusion-limitation of the gas transport through the water phase. Gas is found to be metastably enriched in the water phase with a concentration decreasing away from the <span class="hlt">hydrate</span>-water interface. The initial decomposition process facilitates redistribution of fluid phases in the pore space and local reformation of gas <span class="hlt">hydrates</span>. The observations allow also rationalizing earlier conjectures from experiments with low spatial resolutions and suggest that the <span class="hlt">hydrate</span>-sediment assemblies remain intact until the <span class="hlt">hydrate</span> spacers between sediment grains finally collapse; possible effects on mechanical stability and permeability are discussed. The resulting <span class="hlt">time</span> resolved characteristics of gas <span class="hlt">hydrate</span> decomposition and the influence of melt water on the reaction rate are of importance for a suggested gas recovery from marine sediments by depressurization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810788K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810788K"><span>Forming factors of gas <span class="hlt">hydrate</span> chimney in the Ulleung Basin, East Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Dong-Hyo; Chun, Jong-Hwa; Koo, Nam-Hyng; Kim, Won-Sik; Lee, Ho-Young; Lee, Joo-Yong</p> <p>2016-04-01</p> <p>Seismic chimneys ranging in width from 200 m to 1,000 m are observed in the seismic sections obtained in the Ulleung Basin, East Sea. In consequence of Ulleung Basin Gas <span class="hlt">Hydrate</span> Expedition 1 and 2, concentrations of gas <span class="hlt">hydrates</span> were identified. Especially, 6 chimney sites were drilled and the occurrence of gas <span class="hlt">hydrate</span> was identified at all wells. Through the interpreting seismic section, three factors affect the formation of gas <span class="hlt">hydrate</span> chimney; mass transport deposit, fault, igneous intrusion. These three factors result in three case of forming gas <span class="hlt">hydrate</span> chimney. Firstly, gas <span class="hlt">hydrate</span> chimney appears predominantly in the fault zone. Deep-rooted fault reach to mass transport deposit and gas <span class="hlt">hydrate</span> chimney which is mostly rooted in mass transport deposit is formed. Secondly, Gas <span class="hlt">hydrate</span> chimney appears linked to igneous intrusion. Igneous intrusion result in forming fault in overlying strata. Similar to first case, this fault traverses mass transport deposit and gas <span class="hlt">hydrate</span> chimney rooted in mass transport deposit is created. Thirdly, gas <span class="hlt">hydrate</span> chimney is formed at thick mass transport deposit without fault. In this case, chimney is not reach to seabed in contrast with first and second case. The thickness of mass transport deposit is 0.2 second in two-way travel <span class="hlt">times</span>. Overburden load cause to pressure at the upper part of mass transport deposit. This leads to fracture in overlying sediments and form gas <span class="hlt">hydrate</span> chimney.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P13A1883A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P13A1883A"><span>Effects of CO2 doped ice on CO2 and CH4 <span class="hlt">hydrate</span> formation rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ambuehl, D.; Elwood-Madden, M.</p> <p>2012-12-01</p> <p>Reports of methane plumes on Mars have prompted the proposal of many source and reservoir models for methane, one of which is methane <span class="hlt">hydrate</span>. A <span class="hlt">hydrate</span> reservoir could sequester methane for prolonged periods. This reservoir could form as subsurface methane advects, coming into contact with a layer of permafrost. Within 1.5 m of the Martian surface, the permafrost is likely in communication with the Martian atmosphere. Therefore, diffused atmospheric gases in the ice, especially CO2, could affect <span class="hlt">hydrate</span> formations rates. We tested the effects of diffused CO2 on gas <span class="hlt">hydrate</span> formation rates using CO2 doped and ultrapure water ice. The resulting data was fit with a third order polynomial trend line and the instantaneous rates were determined using the first derivative of the headspace gas pressure vs. <span class="hlt">time</span> curve and normalized for surface area. The results have shown that CO2 <span class="hlt">hydrate</span> formation rates increased by half an order of magnitude and CH4 <span class="hlt">hydrate</span> formation rates increased by an order of magnitude. The accelerated rate of CO2 <span class="hlt">hydrate</span> formation is likely due to clathration of the diffused CO2, making further <span class="hlt">hydrate</span> formation kinetically more favorable. The CH4 <span class="hlt">hydrate</span> formation rates show a greater acceleration due to the thermodynamic stability imparted by a mixed <span class="hlt">hydrate</span> phase. This indicates that CO2 trapped in the permafrost layer would facilitate the formation of near-surface methane <span class="hlt">hydrate</span> on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26618773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26618773"><span>Micromechanical measurements of the effect of surfactants on cyclopentane <span class="hlt">hydrate</span> shell properties.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Erika P; Koh, Carolyn A</p> <p>2016-01-07</p> <p>Investigating the effect of surfactants on clathrate <span class="hlt">hydrate</span> growth and morphology, especially particle shell strength and cohesion force, is critical to advancing new strategies to mitigate <span class="hlt">hydrate</span> plug formation. In this study, dodecylbenzenesulfonic acid and polysorbate 80 surfactants were included during the growth of cyclopentane <span class="hlt">hydrates</span> at several concentrations above and below the critical micelle concentration. A novel micromechanical method was applied to determine the force required to puncture the <span class="hlt">hydrate</span> shell using a glass cantilever (with and without surfactants), with annealing <span class="hlt">times</span> ranging from immediately after the <span class="hlt">hydrate</span> nucleated to 90 minutes after formation. It was shown that the puncture force was decreased by the addition of both surfactants up to a maximum of 79%. Over the entire range of annealing <span class="hlt">times</span> (0-90 minutes), the thickness of the <span class="hlt">hydrate</span> shell was also measured. However, there was no clear change in shell thickness with the addition of surfactants. The growth rate of the <span class="hlt">hydrate</span> shell was found to vary less than 15% with the addition of surfactants. The cohesive force between two <span class="hlt">hydrate</span> particles was measured for each surfactant and found to be reduced by 28% to 78%. Interfacial tension measurements were also performed. Based on these results, microscopic changes to the <span class="hlt">hydrate</span> shell morphology (due to the presence of surfactants) were proposed to cause the decrease in the force required to break the <span class="hlt">hydrate</span> shell, since no macroscopic morphology changes were observed. Understanding the <span class="hlt">hydrate</span> shell strength can be critical to reducing the capillary bridge interaction between <span class="hlt">hydrate</span> particles or controlling the release of unconverted water from the interior of the <span class="hlt">hydrate</span> particle, which can cause rapid <span class="hlt">hydrate</span> conversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2908954','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2908954"><span>Water, <span class="hlt">Hydration</span> and Health</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Popkin, Barry M.; D’Anci, Kristen E.; Rosenberg, Irwin H.</p> <p>2010-01-01</p> <p>This review attempts to provide some sense of our current knowledge of water including overall patterns of intake and some factors linked with intake, the complex mechanisms behind water homeostasis, the effects of variation in water intake on health and energy intake, weight, and human performance and functioning. Water represents a critical nutrient whose absence will be lethal within days. Water’s importance for prevention of nutrition-related noncommunicable diseases has emerged more recently because of the shift toward large proportions of fluids coming from caloric beverages. Nevertheless, there are major gaps in knowledge related to measurement of total fluid intake, <span class="hlt">hydration</span> status at the population level, and few longer-term systematic interventions and no published random-controlled longer-term trials. We suggest some ways to examine water requirements as a means to encouraging more dialogue on this important topic. PMID:20646222</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JChPh.127p4311L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JChPh.127p4311L"><span><span class="hlt">Hydrated</span> hydride anion clusters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Han Myoung; Kim, Dongwook; Singh, N. Jiten; Kołaski, Maciej; Kim, Kwang S.</p> <p>2007-10-01</p> <p>On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion <span class="hlt">hydrated</span> by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6495179','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6495179"><span>Value of periangiography <span class="hlt">hydration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kerstein, M D; Puyau, F A</p> <p>1984-11-01</p> <p>The value of contrast dye to the planning and evaluation of cardiovascular disease cannot be overestimated. However, adverse renal sequellae may cause the surgeon to hesitate in obtaining an arteriogram, especially in patients with compromised renal function. The purpose of this study was to evaluate the incidence of renal dysfunction in patients requiring angiography. Standard contrast angiography for cerebral or peripheral vascular disease was administered to 150 consecutive patients (89 men and 61 women), with an average age of 63.3 years (range 49 to 89 years). All patients received 100 to 150 ml of dye, with a concentration of approximately 50% iodine. Patients were <span class="hlt">hydrated</span> with 0.5 N saline/5% dextrose, intravenously, for 8 hours before the procedure (1 to 3 ml/kg/hr). In 31 patients (11 women and 20 men) the serum BUN and/or creatinine levels were elevated (mean BUN value of 48 +/- 9 mg/dl; mean creatinine level of 2.8 +/- 0.6 mg/dl). The patients with abnormal renal function received an additional 300 to 500 ml of intravenous fluid, plus 20 to 40 mg intravenous furosemide, 1 hour before roentgenography to establish a diuresis. All patients were <span class="hlt">hydrated</span> for 6 hours after angiography with the same solution at the same rate (1 to 3 ml/kg/hr). There were no episodes of compromised renal or cardiopulmonary dysfunction because of contrast angiography. In no patient did the BUN or creatinine level rise, nor was there evidence of acute tubular necrosis, as documented by oliguria and abnormal cells in the urine. Angiography is a safe procedure, even with patients who may have compromised renal function, if appropriate prehydration/posthydration and diuretic measures are undertaken.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H11C1066W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H11C1066W"><span>Balancing Accuracy and Computational Efficiency for Ternary Gas <span class="hlt">Hydrate</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, M. D.</p> <p>2011-12-01</p> <p>Geologic accumulations of natural gas <span class="hlt">hydrates</span> hold vast organic carbon reserves, which have the potential of meeting global energy needs for decades. Estimates of vast amounts of global natural gas <span class="hlt">hydrate</span> deposits make them an attractive unconventional energy resource. As with other unconventional energy resources, the challenge is to economically produce the natural gas fuel. The gas <span class="hlt">hydrate</span> challenge is principally technical. Meeting that challenge will require innovation, but more importantly, scientific research to understand the resource and its characteristics in porous media. Producing natural gas from gas <span class="hlt">hydrate</span> deposits requires releasing CH4 from solid gas <span class="hlt">hydrate</span>. The conventional way to release CH4 is to dissociate the <span class="hlt">hydrate</span> by changing the pressure and temperature conditions to those where the <span class="hlt">hydrate</span> is unstable. The guest-molecule exchange technology releases CH4 by replacing it with a more thermodynamically stable molecule (e.g., CO2, N2). This technology has three advantageous: 1) it sequesters greenhouse gas, 2) it releases energy via an exothermic reaction, and 3) it retains the hydraulic and mechanical stability of the <span class="hlt">hydrate</span> reservoir. Numerical simulation of the production of gas <span class="hlt">hydrates</span> from geologic deposits requires accounting for coupled processes: multifluid flow, mobile and immobile phase appearances and disappearances, heat transfer, and multicomponent thermodynamics. The ternary gas <span class="hlt">hydrate</span> system comprises five components (i.e., H2O, CH4, CO2, N2, and salt) and the potential for six phases (i.e., aqueous, liquid CO2, gas, <span class="hlt">hydrate</span>, ice, and precipitated salt). The equation of state for ternary <span class="hlt">hydrate</span> systems has three requirements: 1) phase occurrence, 2) phase composition, and 3) phase properties. Numerical simulation of the production of geologic accumulations of gas <span class="hlt">hydrates</span> have historically suffered from relatively slow execution <span class="hlt">times</span>, compared with other multifluid, porous media systems, due to strong nonlinearities and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22395940','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22395940"><span>Study on the <span class="hlt">hydration</span> and microstructure of Portland cement containing diethanol-isopropanolamine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ma, Suhua Li, Weifeng; Zhang, Shenbiao; Hu, Yueyang; Shen, Xiaodong</p> <p>2015-01-15</p> <p>Diethanol-isopropanolamine (DEIPA) is a tertiary alkanolamine used in the formulation of cement grinding-aid additives and concrete early-strength agents. In this research, isothermal calorimetry was used to study the <span class="hlt">hydration</span> kinetics of Portland cement with DEIPA. A combination of X-ray <span class="hlt">powder</span> diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC)–thermogravimetric (TG) analysis and micro-Raman spectroscopy was used to investigate the phase development in the process of <span class="hlt">hydration</span>. Mercury intrusion porosimetry was used to study the pore size distribution and porosity. The results indicate that DEIPA promotes the formation of ettringite (AFt) and enhances the second <span class="hlt">hydration</span> rate of the aluminate and ferrite phases, the transformation of AFt into monosulfoaluminate (AFm) and the formation of microcrystalline portlandite (CH) at early stages. At later stages, DEIPA accelerates the <span class="hlt">hydration</span> of alite and reduces the pore size and porosity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70177099','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70177099"><span>Low-δD <span class="hlt">hydration</span> rinds in Yellowstone perlites record rapid syneruptive <span class="hlt">hydration</span> during glacial and interglacial conditions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bindeman, Ilya N.; Lowenstern, Jacob B.</p> <p>2016-01-01</p> <p><span class="hlt">Hydration</span> of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant “onion-skin” fractures. The <span class="hlt">timing</span> and temperature of perlite formation are enigmatic and could plausibly occur during eruption, during post-eruptive cooling, or much later at ambient temperatures. To learn more about the origin of natural perlite, and to fingerprint the <span class="hlt">hydration</span> waters, we investigated perlitic glass from several synglacial and interglacial rhyolitic lavas and tuffs from the Yellowstone volcanic system. Perlitic cores are surrounded by a series of conchoidal cracks that separate 30- to 100-µm-thick slivers, likely formed in response to <span class="hlt">hydration</span>-induced stress. H2O and D/H profiles confirm that most D/H exchange happens together with rapid H2O addition but some smoother D/H variations may suggest separate minor exchange by deuterium atom interdiffusion following <span class="hlt">hydration</span>. The <span class="hlt">hydrated</span> rinds (2–3 wt% H2O) transition rapidly (within 30 µm, or by 1 wt% H2O per 10 µm) to unhydrated glass cores. This is consistent with quenched “<span class="hlt">hydration</span> fronts” where H2O diffusion coefficients are strongly dependent on H2O concentrations. The chemical, δ18O, and δD systematics of bulk glass records last equilibrium between ~110 and 60 °C without chemical exchange but with some δ18O exchange. Similarly, the δ18O of water extracted from glass by rapid heating suggests that water was added to the glass during cooling at <200 °C. Our observations support fast <span class="hlt">hydration</span> at temperatures as low as 60 °C; prolonged exposure to high temperature of 175°–225° during water addition is less likely as the glass would lose alkalies and should alter to clays within days. A compilation of low-temperature <span class="hlt">hydration</span> diffusion coefficients suggests ~2 orders of magnitude higher rates of diffusion at 60–110 °C temperatures, compared with values expected from extrapolation of high-temperature (>400 °C) experimental data. The thick</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoMP..171...89B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoMP..171...89B"><span>Low-δD <span class="hlt">hydration</span> rinds in Yellowstone perlites record rapid syneruptive <span class="hlt">hydration</span> during glacial and interglacial conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bindeman, Ilya N.; Lowenstern, Jacob B.</p> <p>2016-11-01</p> <p><span class="hlt">Hydration</span> of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant "onion-skin" fractures. The <span class="hlt">timing</span> and temperature of perlite formation are enigmatic and could plausibly occur during eruption, during post-eruptive cooling, or much later at ambient temperatures. To learn more about the origin of natural perlite, and to fingerprint the <span class="hlt">hydration</span> waters, we investigated perlitic glass from several synglacial and interglacial rhyolitic lavas and tuffs from the Yellowstone volcanic system. Perlitic cores are surrounded by a series of conchoidal cracks that separate 30- to 100-µm-thick slivers, likely formed in response to <span class="hlt">hydration</span>-induced stress. H2O and D/H profiles confirm that most D/H exchange happens together with rapid H2O addition but some smoother D/H variations may suggest separate minor exchange by deuterium atom interdiffusion following <span class="hlt">hydration</span>. The <span class="hlt">hydrated</span> rinds (2-3 wt% H2O) transition rapidly (within 30 µm, or by 1 wt% H2O per 10 µm) to unhydrated glass cores. This is consistent with quenched "<span class="hlt">hydration</span> fronts" where H2O diffusion coefficients are strongly dependent on H2O concentrations. The chemical, δ18O, and δD systematics of bulk glass records last equilibrium between 110 and 60 °C without chemical exchange but with some δ18O exchange. Similarly, the δ18O of water extracted from glass by rapid heating suggests that water was added to the glass during cooling at <200 °C. Our observations support fast <span class="hlt">hydration</span> at temperatures as low as 60 °C; prolonged exposure to high temperature of 175°-225° during water addition is less likely as the glass would lose alkalies and should alter to clays within days. A compilation of low-temperature <span class="hlt">hydration</span> diffusion coefficients suggests 2 orders of magnitude higher rates of diffusion at 60-110 °C temperatures, compared with values expected from extrapolation of high-temperature (>400 °C) experimental data. The thick <span class="hlt">hydration</span> rinds in perlites</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18671355','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18671355"><span>Alcohol cosurfactants in <span class="hlt">hydrate</span> antiagglomeration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>York, J Dalton; Firoozabadi, Abbas</p> <p>2008-08-28</p> <p>Because of availability, as well as economical and environmental considerations, natural gas is projected to be the premium fuel of the 21st century. Natural gas production involves risk of the shut down of onshore and offshore operations because of blockage from <span class="hlt">hydrates</span> formed from coproduced water and <span class="hlt">hydrate</span>-forming species in natural gas. Industry practice has been usage of thermodynamic inhibitors such as alcohols often in significant amounts, which have undesirable environmental and safety impacts. Thermodynamic inhibitors affect bulk-phase properties and inhibit <span class="hlt">hydrate</span> formation. An alternative is changing surface properties through usage of polymers and surfactants, effective at 0.5 to 3 weight % of coproduced water. One group of low dosage <span class="hlt">hydrate</span> inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are antiagglomerants, which prevent agglomeration of small <span class="hlt">hydrate</span> crystallites. Despite great potential, work on <span class="hlt">hydrate</span> antiagglomeration is very limited. This work centers on the effect of small amounts of alcohol cosurfactant in mixtures of two vastly different antiagglomerants. We use a model oil, water, and tetrahydrofuran as a <span class="hlt">hydrate</span>-forming species. Results show that alcohol cosurfactants may help with antiagglomeration when traditional antiagglomerants alone are ineffective. Specifically, as low as 0.5 wt. % methanol cosurfactant used in this study is shown to be effective in antiagglomeration. Without the cosurfactant there will be agglomeration independent of the AA concentration. To our knowledge, this is the first report of alcohol cosurfactants in <span class="hlt">hydrate</span> antiagglomerants. It is also shown that a rhamnolipid biosurfactant is effective down to only 0.5 wt. % in such mixtures, yet a quaternary ammonium chloride salt, i. e., quat, results in <span class="hlt">hydrate</span> slurries down to 0.01 wt. %. However, biochemical surfactants are less toxic and biodegradable, and thus their use may prove beneficial even if at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=245832','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=245832"><span>Development of Multiplex Real-<span class="hlt">time</span> PCR with Internal Amplification Control for Simultaneous Detection of Salmonella and Cronobacter sakazakii in <span class="hlt">Powdered</span> Infant Formula.</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Contamination of <span class="hlt">powdered</span> infant formula (PIF) by the bacteria Cronobacter sakazakii and Salmonella enterica was deemed a matter of great concern by the World Health Organization and the Food and Agriculture Organization of the United Nations in 2004. Therefore, we developed a rapid and sensitive m...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25754185','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25754185"><span>A novel microwave sensor for real-<span class="hlt">time</span> online monitoring of roll compacts of pharmaceutical <span class="hlt">powders</span> online--a comparative case study with NIR.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gupta, Anshu; Austin, John; Davis, Sierra; Harris, Michael; Reklaitis, Gintaras</p> <p>2015-05-01</p> <p>Control of particulate processes is hard to achieve because of the ease with which <span class="hlt">powders</span> tend to segregate. Thus, proper sensing methods must be employed to ensure content uniformity during operation. The role of sensing schemes becomes even more critical while operating the process continuously as measurements are essential for implementation of feedback control (Austin et al. 2013. J Pharm Sci 102(6):1895-1904; Austin et al. 2014. Anal Chim Acta 819:82-93). A microwave sensor was developed and shown to be effective in online measurement of active pharmaceutical ingredient (API) concentration in a <span class="hlt">powder</span> blend. During <span class="hlt">powder</span> transport and hopper storage before processing, <span class="hlt">powder</span> blends may segregate and cause quality deviations in the subsequent tableting operation. Therefore, it is critical to know the API concentration in the ribbons as the content uniformity is fixed once the ribbon is processed. In this study, a novel microwave sensor was developed that could provide measurement of a roller compacted ribbon's API concentration online, along with its density and moisture content. The results indicate that this microwave sensor is capable of increased accuracy compared with a commercially available near-IR probe for the determination of content uniformity and density in roller compacted ribbons online.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2491167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2491167"><span>[Setting characteristics of calcia-bonded investments by <span class="hlt">hydration</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nishimura, F; Watari, F; Nomoto, S</p> <p>1989-07-01</p> <p>Calcium oxide (CaO) slurry mixed with water hardens and expands by <span class="hlt">hydration</span>. The authors used this setting characteristic as a binder of zirconia-refractory investments. If a mixed slurry was placed in air, unreacted residual calcia <span class="hlt">powders</span> absorbed water and reverted to calcium hydroxide (Ca (OH)2). This resulted in a large setting expansion that continued for several days. A carbon dioxide (CO2) gas atmosphere controlled this expansion of calcia. When mixed slurry was placed in a carbon dioxide gas atmosphere, calcium carbonate (CaCO3) was formed and prevented the further <span class="hlt">hydration</span> of unreacted calcium oxide. Thus setting expansion values were controlled. The combined expansion of setting and thermal expansion, in CaO-CO2-bonded zirconia investments, was about 1.5-2.5%. On the whole, calcium oxide is expected to be a good binder for high temperature dental casting refractory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V24B..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V24B..01A"><span><span class="hlt">Hydration</span> of Rhyolitic Glasses: Comparison Between High- and Low-Temperature Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anovitz, L.; Fayek, M.; Cole, D. R.; Carter, T.</p> <p>2012-12-01</p> <p>While a great deal is known about the interaction between water and rhyolitic glasses and melts at temperatures above the glass transition, the nature of this interaction at lower temperatures is more obscure. Comparisons between high- and low-temperature diffusive studies suggest that several factors play an important role under lower-temperatures conditions that are not significant at higher temperatures. Surface concentrations, which equilibrate quickly at high temperature, change far more slowly as temperatures decrease, and may not equilibrate at room temperature for hundreds or thousands of years. Coupled with temperature-dependent diffusion coefficients this complicates calculation of diffusion profiles as a function of <span class="hlt">time</span>. A key factor in this process appears to be the inability of "self-stress", caused by the in-diffusing species, to relax at lower temperatures, a result expected below the glass transition. Regions of the glass <span class="hlt">hydrated</span> at low temperatures are strongly optically anisotropic, and preliminary calculations suggest that the magnitude of stress involved may be very high. On the microstuctural scale, extrapolations of high-temperature FTIR data to lower temperatures suggests there should be little or no hydroxyl present in glasses "<span class="hlt">hydrated</span>" at low temperatures. Analyses of both block and <span class="hlt">powder</span> samples suggest that this is generally true in the bulk of the <span class="hlt">hydrated</span> glass, excluding hydroxyl groups that formed during the initial cooling of the melt. However, hydroxyl do groups appear to be present at the glass surface, where both SIMS and neutron reflectometry data suggest <span class="hlt">hydration</span> levels may be higher than projected from the bulk of the glass. Isotopic exchange experiments also suggest that bonding is relatively weak, as <span class="hlt">hydration</span> water exchanges readily with the enviroment. All of these observations lead to the conclusion that the observed stress is due to the presence of interstructural, rather than bonded, water. This likely explains the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016649','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016649"><span>Thermal Regeneration of Sulfuric Acid <span class="hlt">Hydrates</span> after Irradiation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Loeffler, Mark J.; Hudson, Reggie L.</p> <p>2012-01-01</p> <p>In an attempt to more completely understand the surface chemistry of the jovian icy satellites, we have investigated the effect of heating on two irradiated crystalline sulfuric acid <span class="hlt">hydrates</span>, H2SO4 4H2O and H2SO4 H2O. At temperatures relevant to Europa and the warmer jovian satellites, post-irradiation heating recrystallized the amorphized samples and increased the intensities of the remaining <span class="hlt">hydrate</span>'s infrared absorptions. This thermal regeneration of the original <span class="hlt">hydrates</span> was nearly 100% efficient, indicating that over geological <span class="hlt">times</span>, thermally-induced phase transitions enhanced by temperature fluctuations will reform a large fraction of crystalline <span class="hlt">hydrated</span> sulfuric acid that is destroyed by radiation processing. The work described is the first demonstration of the competition between radiation-induced amorphization and thermally-induced recrystallization in icy ionic solids relevant to the outer Solar System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26292230','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26292230"><span>Homogeneous Nucleation of Methane <span class="hlt">Hydrate</span> in Microsecond Molecular Dynamics Simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sarupria, Sapna; Debenedetti, Pablo G</p> <p>2012-10-18</p> <p>We report atomistically detailed molecular dynamics simulations of homogeneous nucleation of methane <span class="hlt">hydrate</span> in bulk aqueous phase in the absence of any interface. Subcritical clusters of water and methane molecules are formed in the initial segment of the simulations, which then aggregate to give the critical <span class="hlt">hydrate</span> nucleus. This occurs over <span class="hlt">time</span> scales of several hundred nanoseconds, indicating that the formation and aggregation of subcritical clusters can contribute significantly to the overall rate of <span class="hlt">hydrate</span> nucleation. The clusters have elements of sI <span class="hlt">hydrate</span> structure, such as 5(12) and 5(12)6(2) cages as well as other uncommon 5(12)6(3) and 5(12)6(4) cages, but do not possess long-range order. Clusters are dynamic in nature and undergo continuous structural rearrangements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22212379','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22212379"><span>Large-scale and shape-controlled synthesis and characterization of nanorod-like nickel <span class="hlt">powders</span> under microwave radiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guo, Yajie; Wang, Guangjian; Wang, Yuran; Huang, Yanhong; Wang, Fei</p> <p>2012-01-15</p> <p>Graphical abstract: The nanorod-like pure nickel were fabricated via hydrothermal liquid phase reduction route under microwave irradiation with hydrazine <span class="hlt">hydrate</span> as a reducing agent as well as polyvinyl alcohol as a dispersant and/or structure directing agent. The materials were characterized by XRD, SEM, EDS, HRTEM, and selected-area electron diffraction, etc. The lattice expansion for Ni <span class="hlt">powders</span> was explained in detail. As-prepared Ni sample was of obvious shape anisotropy with length diameter ratio of 5. Magnetic measurements shown that the magnetic properties of Ni nanorod-like (fcc) were quite different from those of hexagonal closed-packed (hcp) Ni nanoparticles. Highlights: Black-Right-Pointing-Pointer The synthesis of nanorod-like nickel under microwave irradiation. Black-Right-Pointing-Pointer Nitrogen generated in reaction as a shielding gas. Black-Right-Pointing-Pointer The lattice expansion for Ni <span class="hlt">powders</span> was explained in detail. Black-Right-Pointing-Pointer Magnetic properties of Ni were quite different from those of Ni nanoparticles. -- Abstract: The nanorod-like nickel <span class="hlt">powders</span> were fabricated via hydrothermal liquid phase reduction route under microwave irradiation with hydrazine <span class="hlt">hydrate</span> as a reducing agent as well as polyvinyl alcohol as a dispersant and/or structure directing agent. The morphology and structure of as-prepared products could be easily tuned by adjusting process parameters such as pH value and microwave irradiation <span class="hlt">time</span>. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscope, transmission electron microscopy and selected-area electron diffraction (SAED). The results demonstrated that pure nickel <span class="hlt">powders</span> with face-centered cubic (fcc) structure were prepared at relatively mild condition and no characteristic peaks of nickel oxide in the XRD pattern were found. The phenomenon of lattice expansion for Ni <span class="hlt">powders</span> was explained in details according to the XRD theory. As-prepared Ni sample was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27412621','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27412621"><span>Illuminating solid gas storage in confined spaces - methane <span class="hlt">hydrate</span> formation in porous model carbons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Borchardt, Lars; Nickel, Winfried; Casco, Mirian; Senkovska, Irena; Bon, Volodymyr; Wallacher, Dirk; Grimm, Nico; Krause, Simon; Silvestre-Albero, Joaquín</p> <p>2016-07-27</p> <p>Methane <span class="hlt">hydrate</span> nucleation and growth in porous model carbon materials illuminates the way towards the design of an optimized solid-based methane storage technology. High-pressure methane adsorption studies on pre-humidified carbons with well-defined and uniform porosity show that methane <span class="hlt">hydrate</span> formation in confined nanospace can take place at relatively low pressures, even below 3 MPa CH4, depending on the pore size and the adsorption temperature. The methane <span class="hlt">hydrate</span> nucleation and growth is highly promoted at temperatures below the water freezing point, due to the lower activation energy in ice vs. liquid water. The methane storage capacity via <span class="hlt">hydrate</span> formation increases with an increase in the pore size up to an optimum value for the 25 nm pore size model-carbon, with a 173% improvement in the adsorption capacity as compared to the dry sample. Synchrotron X-ray <span class="hlt">powder</span> diffraction measurements (SXRPD) confirm the formation of methane <span class="hlt">hydrates</span> with a sI structure, in close agreement with natural <span class="hlt">hydrates</span>. Furthermore, SXRPD data anticipate a certain contraction of the unit cell parameter for methane <span class="hlt">hydrates</span> grown in small pores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.2129S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.2129S"><span>Temperature- and pressure-dependent structural transformation of methane <span class="hlt">hydrates</span> in salt environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shin, Donghoon; Cha, Minjun; Yang, Youjeong; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Ahn, Docheon; Im, Junhyuck; Lee, Yongjae; Han, Oc Hee; Yoon, Ji-Ho</p> <p>2017-03-01</p> <p>Understanding the stability of volatile species and their compounds under various surface and subsurface conditions is of great importance in gaining insights into the formation and evolution of planetary and satellite bodies. We report the experimental results of the temperature- and pressure-dependent structural transformation of methane <span class="hlt">hydrates</span> in salt environments using in situ synchrotron X-ray <span class="hlt">powder</span> diffraction, solid-state nuclear magnetic resonance, and Raman spectroscopy. We find that under pressurized and concentrated brine solutions methane <span class="hlt">hydrate</span> forms a mixture of type I clathrate <span class="hlt">hydrate</span>, ice, and <span class="hlt">hydrated</span> salts. Under a low-pressure condition, however, the methane <span class="hlt">hydrates</span> are decomposed through a rapid sublimation of water molecules from the surface of <span class="hlt">hydrate</span> crystals, while NaCl · 2H2O undergoes a phase transition into a crystal growth of NaCl via the migration of salt ions. In ambient pressure conditions, the methane <span class="hlt">hydrate</span> is fully decomposed in brine solutions at temperatures above 252 K, the eutectic point of NaCl · 2H2O.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25223726','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25223726"><span>Solid-state characterization and transformation of various creatine phosphate sodium <span class="hlt">hydrates</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Yun; Jiang, Linglei; Huang, Ying; Wang, Jian-Rong; Mei, Xuefeng</p> <p>2014-11-01</p> <p>Creatine phosphate sodium (CPS) salt is a first-line cardiovascular drug for severe diastolic heart failure. The drug exists in different <span class="hlt">hydrate</span> forms. The marketed drug form was determined as CPS·4.5H2 O (H1); however, the reference standard was supplied as CPS·6H2 O (H2). In this work, we present two newly identified <span class="hlt">hydrate</span> forms: a thermodynamically stable low <span class="hlt">hydrate</span> form, CPS·1.5H2 O (H3), and a pressure-sensitive transit form, CPS·7H2 O (H4). The <span class="hlt">hydrate</span> forms were discovered through a comprehensive solid-state screening experiment and fully characterized using a range of analytical techniques including X-ray <span class="hlt">powder</span> diffraction (XRPD), FTIR, Raman spectroscopy, hot-stage microscopy (HSM), thermogravimetric analysis, and differential scanning calorimetry. Stability tests revealed that H3 was the most stable <span class="hlt">hydrate</span> under thermal stimulation. H4 is a pressure-sensitive <span class="hlt">hydrate</span> and easily transforms to H2 and then H1 upon grinding. The form transformation process was closely monitored using the HSM, variable-temperature XRPD (VT-XRPD), and VT-Raman spectroscopy techniques. Specifically, the transformation of H4 to H1 is characterized in a single-crystal-to-single-crystal transformation process. The newly discovered <span class="hlt">hydrate</span> form H3 has superior physicochemical properties than the marketed forms and is worthy of further development. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26017360','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26017360"><span><span class="hlt">Hydrated</span> Electron Transfer to Nucleobases in Aqueous Solutions Revealed by Ab Initio Molecular Dynamics Simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Jing; Wang, Mei; Fu, Aiyun; Yang, Hongfang; Bu, Yuxiang</p> <p>2015-08-03</p> <p>We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped <span class="hlt">hydrated</span> electron state to a <span class="hlt">hydrated</span> nucleobase (NB)-bound state. In contrast to the traditional view that electron localization at NBs (G/A/C/T), which is the first step for electron-induced DNA damage, is related only to dry or prehydrated electrons, and a fully <span class="hlt">hydrated</span> electron no longer transfers to NBs, our AIMD simulations indicate that a fully <span class="hlt">hydrated</span> electron can still transfer to NBs. We monitored the transfer dynamics of fully <span class="hlt">hydrated</span> electrons towards <span class="hlt">hydrated</span> NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully <span class="hlt">hydrated</span> electron can transfer to a NB gradually over <span class="hlt">time</span>. Concurrently, the <span class="hlt">hydrated</span> electron cavity gradually reorganizes, distorts, and even breaks. The transfer could be completed in about 120-200 fs in four aqueous NB solutions, depending on the electron-binding ability of <span class="hlt">hydrated</span> NBs and the structural fluctuation of the solution. The transferring electron resides in the π*-type lowest unoccupied molecular orbital of the NB, which leads to a <span class="hlt">hydrated</span> NB anion. Clearly, the observed transfer of <span class="hlt">hydrated</span> electrons can be attributed to the strong electron-binding ability of <span class="hlt">hydrated</span> NBs over the <span class="hlt">hydrated</span> electron cavity, which is the driving force, and the transfer dynamics is structure-fluctuation controlled. This work provides new insights into the evolution dynamics of <span class="hlt">hydrated</span> electrons and provides some helpful information for understanding the DNA-damage mechanism in solution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16846704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16846704"><span>Spray dried glyceryl monooleate-magnesium trisilicate dry <span class="hlt">powder</span> as cubic phase precursor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shah, Manish H; Biradar, Shailesh V; Paradkar, Anant R</p> <p>2006-10-12</p> <p>Glyceryl monooleate (GMO) is a polar amphiphilic lipid, which forms different sequential lyotropic liquid crystals upon <span class="hlt">hydration</span>. GMO has been utilized for various delivery systems and routes of administrations. Owing to sticky and waxy nature of GMO, preparation of oral solid dosage form utilizing GMO is still a challenge for pharmaceutical researchers. Therefore, the objective of the present work was to fabricate dry <span class="hlt">powder</span> precursors using GMO, which upon <span class="hlt">hydration</span> in situ forms cubic phase and can be wisely used for fabrication of oral solid dosage forms. In addition to this, dry <span class="hlt">powder</span> precursor was evaluated for drug loading, in vitro release behavior and in vivo performance of model drug diclofenac sodium (DiNa). The dry <span class="hlt">powder</span> precursor was obtained by spray-drying GMO with DiNa using magnesium trisilicate (MTS) as adsorbent. The percent drug entrapment of various batches of <span class="hlt">powder</span> precursor was in the range of 84-93% indicating high content uniformity. SEM and image analysis showed that as the amount of MTS in <span class="hlt">powder</span> precursor was increased, the particle size decreased. Furthermore, the viscosity of <span class="hlt">powder</span> precursor was function of amount of MTS. The rate of water uptake of <span class="hlt">powder</span> precursor was higher due to uniform layer of GMO on the MTS surface, which led to faster transformation of lamellar phase into cubic phase. The polarizing light microscopy confirmed that cubic phase was formed upon <span class="hlt">hydration</span> of <span class="hlt">powder</span> precursor. The drug released from <span class="hlt">powder</span> precursor was initially governed by the cubic phase formed and in later stage it depends upon dynamic swelling behavior of hexagonally packed cylindrical aggregates. The drug loaded <span class="hlt">powder</span> precursor was found to have more effective and prolonged anti-inflammatory and analgesic activity as compared to pure drug. Thus the dry <span class="hlt">powder</span> precursor of cubic phase was prepared in which drug release was entirely governed by the mesophases formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JCrGr.204..525D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JCrGr.204..525D"><span>THF water <span class="hlt">hydrate</span> crystallization: an experimental investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Devarakonda, Surya; Groysman, Alexander; Myerson, Allan S.</p> <p>1999-08-01</p> <p>Supersaturated solutions of THF-water <span class="hlt">hydrate</span> system were experimentally studied before and during crystallization, to examine the system's behavior in the metastable zone and observe any anomalies suggesting cluster formation. Nucleation induction <span class="hlt">time</span> measurements, with and without additives, were performed to screen potential growth inhibitors. Shifts in the onset points of crystallization for water and THF-water mixtures with additives were measured using differential scanning calorimetry (DSC). Aspartame was among one of the few successfully screened inhibitors. Preliminary on-line crystal size distribution (CSD) measurements were performed on this system to monitor the crystal size during crystallization. The CSD data was also used to compute the <span class="hlt">hydrate</span> crystal growth rates, which were found to be in the order of 145 μm/h.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1045030','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1045030"><span>Simultaneous study of mechanical property development and early <span class="hlt">hydration</span> chemistry in Portland cement slurries using X-ray diffraction and ultrasound reflection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jupe, Andrew C.; Wilkinson, Angus P.; Funkhouser, Gary P.</p> <p>2012-10-25</p> <p>A sample cell for the simultaneous measurement of synchrotron X-ray <span class="hlt">powder</span> diffraction and ultrasound shear-wave reflection data from cement slurries is described. White cement slurries at 25 and 50 C with 0-3% bwoc CaCl{sub 2} were studied to illustrate the potential of the apparatus. The decrease in reflected S-wave amplitude, in dB, showed a linear correlation with C{sub 3}S <span class="hlt">hydration</span>. CaCl{sub 2} retarded the development of G{prime} and G{double_prime} relative to the extent of C{sub 3}S <span class="hlt">hydration</span>. At short <span class="hlt">times</span>, there was a correlation between the <span class="hlt">time</span> evolution of both G{prime} and G{double_prime}, and the amount of precipitated CH seen by diffraction, which was almost independent of CaCl{sub 2} concentration and temperature. CaCl{sub 2} addition resulted in a decrease in the amount of CH visible to X-rays, relative the degree of C{sub 3}S <span class="hlt">hydration</span>. This may indicate a change in C-S-H gel C:S ratio or the presence of nanoscale CH that could not be seen by diffraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19127652','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19127652"><span>Antiviral activities of heated dolomite <span class="hlt">powder</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Motoike, Koichi; Hirano, Shozo; Yamana, Hideaki; Onda, Tetsuhiko; Maeda, Takayoshi; Ito, Toshihiro; Hayakawa, Motozo</p> <p>2008-12-01</p> <p>The effect of the heating conditions of dolomite <span class="hlt">powder</span> on its antiviral activity was studied against the H5N3 avian influenza virus. Calcium oxide (CaO) and magnesium oxide (MgO), obtained by the thermal decomposition of dolomite above 800 degrees C, were shown to have strong antiviral activity, but the effect was lessened when the heating temperature exceeded 1400 degrees C. Simultaneous measurement of the crystallite size suggested that the weakening of the activity was due to the considerable grain growth of the oxides. It was found that the presence of Mg in dolomite contributed to the deterrence of grain growth of the oxides during the heating process. Although both CaO and MgO exhibited strong antiviral activity, CaO had the stronger activity but quickly <span class="hlt">hydrated</span> in the presence of water. On the other hand, the <span class="hlt">hydration</span> of MgO took place gradually under the same conditions. Separate measurements using MgO and Mg(OH)2 revealed that MgO had a higher antiviral effect than Mg(OH)2. From the overall experiments, it was suggested that the strong antiviral activity of dolomite was related to the <span class="hlt">hydration</span> reaction of CaO.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22224345','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22224345"><span>Compressive strength and <span class="hlt">hydration</span> processes of concrete with recycled aggregates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Koenders, Eduardus A.B.; Pepe, Marco; Martinelli, Enzo</p> <p>2014-02-15</p> <p>This paper deals with the correlation between the <span class="hlt">time</span> evolution of the degree of <span class="hlt">hydration</span> and the compressive strength of Recycled Aggregate Concrete (RAC) for different water to cement ratios and initial moisture conditions of the Recycled Concrete Aggregates (RCAs). Particularly, the influence of such moisture conditions is investigated by monitoring the <span class="hlt">hydration</span> process and determining the compressive strength development of fully dry or fully saturated recycled aggregates in four RAC mixtures. <span class="hlt">Hydration</span> processes are monitored via temperature measurements in hardening concrete samples and the <span class="hlt">time</span> evolution of the degree of <span class="hlt">hydration</span> is determined through a 1D <span class="hlt">hydration</span> and heat flow model. The effect of the initial moisture condition of RCAs employed in the considered concrete mixtures clearly emerges from this study. In fact, a novel conceptual method is proposed to predict the compressive strength of RAC-systems, from the initial mixture parameters and the hardening conditions. -- Highlights: •The concrete industry is more and more concerned with sustainability issues. •The use of recycled aggregates is a promising solution to enhance sustainability. •Recycled aggregates affect both <span class="hlt">hydration</span> processes and compressive strength. •A fundamental approach is proposed to unveil the influence of recycled aggregates. •Some experimental comparisons are presented to validate the proposed approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003CaJPh..81...17Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003CaJPh..81...17Z"><span>The inhibition of tetrahydrofuran clathrate-<span class="hlt">hydrate</span> formation with antifreeze protein</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, H.; Wilson, L. D.; Walker, V. K.; Ripmeester, J. A.</p> <p>2003-01-01</p> <p>The effect of Type I fish antifreeze protein (AFP) from the winter flounder, Pleuronectes americanus (Walbaum), (WfAFP) on the formation of tetrahydrofuran (THF) clathrate <span class="hlt">hydrate</span> was studied by observing changes in THF crystal morphology and determining the induction <span class="hlt">time</span> for nucleation. AFP retarded THF clathrate-<span class="hlt">hydrate</span> growth at the tested temperatures and modified the THF clathrate-<span class="hlt">hydrate</span> crystal morphology from octahedral to plate-like. AFP appears to be even more effective than the kinetic inhibitor, polyvinylpyrrolidone (PVP). Recombinant AFP from an insect, a spruce budworm, Choristoneura fumiferana (Clem.), moth, (Cf) was also tested for inhibition activity by observation of the THF-<span class="hlt">hydrate</span>-crystal-growth habit. Like WfAFP, CfAFP appeared to show adsorption on multiple THF-<span class="hlt">hydrate</span>-crystal faces. A protein with no antifreeze activity, cytochrome C, was used as a control and it neither changed the morphology of the THF clathrate-<span class="hlt">hydrate</span> crystals, nor retarded the formation of the <span class="hlt">hydrate</span>. Preliminary experiments on the inhibition activity of WfAFP on a natural gas <span class="hlt">hydrate</span> assessed induction <span class="hlt">time</span> and the amount of propane gas consumed. Similar to the observations for THF, the data indicated that WfAFP inhibited propane-<span class="hlt">hydrate</span> growth. Taken together, these results support our hypothesis that AFPs can inhibit clathrate-<span class="hlt">hydrate</span> growth and as well, offer promise for the understanding of the inhibition mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1050730','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1050730"><span>Examination of <span class="hlt">Hydrate</span> Formation Methods: Trying to Create Representative Samples</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kneafsey, T.J.; Rees, E.V.L.; Nakagawa, S.; Kwon, T.-H.</p> <p>2011-04-01</p> <p>Forming representative gas <span class="hlt">hydrate</span>-bearing laboratory samples is important so that the properties of these materials may be measured, while controlling the composition and other variables. Natural samples are rare, and have often experienced pressure and temperature changes that may affect the property to be measured [Waite et al., 2008]. Forming methane <span class="hlt">hydrate</span> samples in the laboratory has been done a number of ways, each having advantages and disadvantages. The ice-to-<span class="hlt">hydrate</span> method [Stern et al., 1996], contacts melting ice with methane at the appropriate pressure to form <span class="hlt">hydrate</span>. The <span class="hlt">hydrate</span> can then be crushed and mixed with mineral grains under controlled conditions, and then compacted to create laboratory samples of methane <span class="hlt">hydrate</span> in a mineral medium. The <span class="hlt">hydrate</span> in these samples will be part of the load-bearing frame of the medium. In the excess gas method [Handa and Stupin, 1992], water is distributed throughout a mineral medium (e.g. packed moist sand, drained sand, moistened silica gel, other porous media) and the mixture is brought to <span class="hlt">hydrate</span>-stable conditions (chilled and pressurized with gas), allowing <span class="hlt">hydrate</span> to form. This method typically produces grain-cementing <span class="hlt">hydrate</span> from pendular water in sand [Waite et al., 2004]. In the dissolved gas method [Tohidi et al., 2002], water with sufficient dissolved guest molecules is brought to <span class="hlt">hydrate</span>-stable conditions where <span class="hlt">hydrate</span> forms. In the laboratory, this is can be done by pre-dissolving the gas of interest in water and then introducing it to the sample under the appropriate conditions. With this method, it is easier to form <span class="hlt">hydrate</span> from more soluble gases such as carbon dioxide. It is thought that this method more closely simulates the way most natural gas <span class="hlt">hydrate</span> has formed. Laboratory implementation, however, is difficult, and sample formation is prohibitively <span class="hlt">time</span> consuming [Minagawa et al., 2005; Spangenberg and Kulenkampff, 2005]. In another version of this technique, a specified quantity of gas</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010935','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010935"><span>Obsidian <span class="hlt">hydration</span> dates glacial loading?</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Friedman, I.; Pierce, K.L.; Obradovich, J.D.; Long, W.D.</p> <p>1973-01-01</p> <p>Three different groups of <span class="hlt">hydration</span> rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming . The average thickness of the thickest (oldest) group of <span class="hlt">hydration</span> rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average <span class="hlt">hydration</span> rind thicknesses of 14.5 and 7.9 micrometers. These later two <span class="hlt">hydration</span> rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17806883','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17806883"><span>Obsidian <span class="hlt">hydration</span> dates glacial loading?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Friedman, I; Pierce, K L; Obradovich, J D; Long, W D</p> <p>1973-05-18</p> <p>Three different groups of <span class="hlt">hydration</span> rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of <span class="hlt">hydration</span> rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average <span class="hlt">hydration</span> rind thicknesses of 14.5 and 7.9 micrometers. These later two <span class="hlt">hydration</span> rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMOS22A..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMOS22A..06B"><span>Molecular and dissociation studies of natural gas <span class="hlt">hydrates</span> collected from different oceanic environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bourry, C.; Charlou, J.; Donval, J.; Focsa, C.; Chazallon, B.</p> <p>2007-12-01</p> <p>Natural gas <span class="hlt">hydrates</span> occur globally in marine sediments or in permafrost regions when specific conditions of high pressure, low temperature and sufficiently methane concentration are combined to initiate their formation and stabilize their structure. As well as they appear attractive for gas industry, natural gas <span class="hlt">hydrates</span> can have an important impact in continental slope stability or climate change. Therefore, it is important to focus our attention on structural evolution and thermodynamical stability of these natural minerals. For this, high-resolution <span class="hlt">powder</span> X-ray synchrotron diffraction and Raman spectroscopy techniques are efficient and powerful tools to determine the <span class="hlt">hydrate</span> structures. We performed a first physical characterization of two intact natural gas <span class="hlt">hydrates</span> from the Congo-Angola and the Nigerian margin by X-ray synchrotron diffraction. The collected samples exhibit a preponderance of structure I (sI) (cubic lattice with space group Pm n). The Rietveld refinement of lattice parameters for the type I structure gives values intermediate between lattice constant of less pure methane specimens and pure artificial methane <span class="hlt">hydrates</span>. This indicates that lattice constant can be affected by the presence of encaged CO2, H2S and other gas molecules, even in small amount. Thermal expansion is also presented for Congo-Angola <span class="hlt">hydrate</span> in the temperature range 90-200 K and coefficients are comparable with values reported for synthetic <span class="hlt">hydrates</span> at low temperature, whereas they tend to approach ice thermal expansion coefficient at higher temperature. In a second step, we performed a physical characterization by Raman spectroscopy of natural gas <span class="hlt">hydrates</span> recovered from Haakon Mosby Mud Volcano (Norwegian Margin) during the Vicking cruise (HERMES project, 2006). These samples exhibit as well a preponderance of structure I (sI) embedded in ice originating from frozen pore water and <span class="hlt">hydrate</span> dissociation during recovery. The dissociation temperature (Td) of these <span class="hlt">hydrates</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EPJWC...623005C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EPJWC...623005C"><span>Early-age volume changes of extrudable reactive <span class="hlt">powder</span> concrete</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cherkaoui, K.; Courtial, M.; Dunstetter, F.; Khelidj, A.; Mounanga, P.; de Noirfontaine, M. N.</p> <p>2010-06-01</p> <p>This article presents a study on the early-age autogenous deformations of Extrudable Reactive <span class="hlt">Powder</span> Concretes (ERPCs), especially designed for the making of concrete pipes by extrusion. Different ERPC mixtures, with variable amounts of polycarboxylate superplasticizer (SP), have been investigated. Results on 28-day mechanical properties, early-age <span class="hlt">hydration</span> rate, autogenous shrinkage and premature cracking risk are analyzed and discussed in relation with the ERPC mix parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1329579','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1329579"><span>Oxidation and <span class="hlt">Hydration</span> of U <sub>3</sub> O <sub>8</sub> Materials Following Controlled Exposure to Temperature and Humidity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tamasi, Alison L.; Boland, Kevin S.; Czerwinski, Kenneth; Ellis, Jason K.; Kozimor, Stosh A.; Martin, Richard L.; Pugmire, Alison L.; Reilly, Dallas; Scott, Brian L.; Sutton, Andrew D.; Wagner, Gregory L.; Walensky, Justin R.; Wilkerson, Marianne P.</p> <p>2015-03-18</p> <p>Chemical signatures correlated with uranium oxide processing are of interest to forensic science for inferring sample provenance. Identification of temporal changes in chemical structures of process uranium materials as a function of controlled temperatures and relative humidities may provide additional information regarding sample history. In our study, a high-purity α-U<sub>3</sub>O<sub>8</sub> sample and three other uranium oxide samples synthesized from reaction routes used in nuclear conversion processes were stored under controlled conditions over 2–3.5 years, and <span class="hlt">powder</span> X-ray diffraction analysis and X-ray absorption spectroscopy were employed to characterize chemical speciation. We measured signatures from the α-U<sub>3</sub>O<sub>8</sub> sample indicated that the material oxidized and <span class="hlt">hydrated</span> after storage under high humidity conditions over <span class="hlt">time</span>. Impurities, such as uranyl fluoride or schoepites, were initially detectable in the other uranium oxide samples. After storage under controlled conditions, the analyses of the samples revealed oxidation over <span class="hlt">time</span>, although the signature of the uranyl fluoride impurity diminished. The presence of schoepite phases in older uranium oxide material is likely indicative of storage under high humidity and should be taken into account for assessing sample history. Finally, the absence of a signature from a chemical impurity, such as uranyl fluoride <span class="hlt">hydrate</span>, in an older material may not preclude its presence at the initial <span class="hlt">time</span> of production. LA-UR-15-21495.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGC51B0953P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGC51B0953P"><span>Precipitation of <span class="hlt">hydrated</span> Mg carbonate with the aid of carbonic anhydrase for CO2 sequestration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Power, I. M.; Harrison, A. L.; Dipple, G. M.</p> <p>2011-12-01</p> <p> and water was sampled for dissolved inorganic carbon (DIC) and magnesium concentrations. Final precipitates were collected for X-ray <span class="hlt">powder</span> diffraction and determination of the percent carbon. The presence of BCA increases the concentration of DIC, thus accelerating the rate-limiting step. In alkaline Mg-rich solutions, disordered <span class="hlt">hydrated</span> magnesium carbonate, resembling dypingite, rapidly precipitated within hours to form micron-wide flakes. At concentrations of 200 and 100 mg BCA/L, the rates of carbon uptake were ~7 and ~4.4 <span class="hlt">times</span> that of the control system during the first 24 hours, respectively. BCA is able to catalyze the <span class="hlt">hydration</span> of CO2 thereby increasing concentrations of DIC relatively rapidly and allowing for the sequestration of atmospheric CO2 as <span class="hlt">hydrated</span> Mg carbonate minerals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P11E1868L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P11E1868L"><span>The Behavior of <span class="hlt">Hydrated</span> Na-Mg Sulfate Phases Under Mars-Relevant Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leftwich, K.; Bish, D. L.</p> <p>2012-12-01</p> <p>An increasing inventory of hydrous evaporite and silicate minerals has been identified from orbital and lander data on Mars. Several hydrous sulfate minerals are thought to be present on Mars, based on spectral, chemical, and geomorphic observations (e.g., CRISM, OMEGA, and Mars Exploration Rover results). We are examining the behavior of hydrous minerals on Mars and their potential participation in the H2O cycle to augment and complement these data. With limited liquid water stability on the martian surface, <span class="hlt">hydration</span> and dehydration of hydrous minerals with changes in temperature (T) and relative humidity (RH) during a Mars day can have a significant influence on the bioavailability of water and potentially on atmospheric H2O. This research focused on the Na2MgSO4nH2O system, predicted by King et al. (2004) to occur on Mars. Phases in this system were also predicted by Clark et al. (1981), based on the concentration of Mg on Mars' surface. They proposed that Mg would be more stable in the form of a double salt, as a result of solubilities in the MgSO4nH2O system. Our experiments included blödite, konyaite, a decahydrate, and potential new phases. Blödite (Na2MgSO44H2O) was analyzed by X-ray <span class="hlt">powder</span> diffraction (XRD) under controlled RH-T conditions to investigate its behavior and to understand mineral reactions. Crystal structures and phase abundances were determined using Rietveld methods. When blödite was allowed to deliquesce (RH>80%) and then exposed to low temperatures (T<0°C), two different results were observed. One set of experiments produced a new, likely higher <span class="hlt">hydrate</span> Na2MgSO4 phase. This new phase was first observed at -10°C (47-78% RH), it formed within minutes, and it persisted on decreasing T to at least -30°C. In an attempt to produce only this phase, a second set of experiments was performed by storing blödite (either dry or in mush form) at -10°C for several days. These experiments produced a mixture of mirabilite (Na2SO410H2O; 56 wt% H2O</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JCrGr.345...61J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JCrGr.345...61J"><span><span class="hlt">Hydrate</span> formation and growth in pores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, Jong-Won; Santamarina, J. Carlos</p> <p>2012-04-01</p> <p>Gas <span class="hlt">hydrates</span> consist of guest gas molecules encaged in water cages. Methane <span class="hlt">hydrate</span> forms in marine and permafrost sediments. In this study, we use optical, mechanical and electrical measurements to monitor <span class="hlt">hydrate</span> formation and growth in small pores to better understand the <span class="hlt">hydrate</span> pore habit in <span class="hlt">hydrate</span>-bearing sediments. <span class="hlt">Hydrate</span> formation in capillary tubes exposes the complex and dynamic interactions between nucleation, gas diffusion and gas solubility. The observation of <span class="hlt">hydrate</span> growth in a droplet between transparent plates shows that the <span class="hlt">hydrate</span> shell does not grow homogeneously but advances in the form of lobes that invade the water phase; in fact, the <span class="hlt">hydrate</span> shell must be discontinuous and possibly cracked to justify the relatively fast growth rates observed in these experiments. Volume expansion during <span class="hlt">hydrate</span> formation causes water to flow out of menisci; expelled water either spreads on the surface of water-wet substrates and forms a thin <span class="hlt">hydrate</span> sheet, or remains next to menisci when substrates are oil-wet. <span class="hlt">Hydrate</span> formation is accompanied by ion exclusion, yet, there is an overall increase in electrical resistance during <span class="hlt">hydrate</span> formation. <span class="hlt">Hydrate</span> growth may become salt-limited in trapped water conditions; in this case, aqueous brine and gas CH4 may be separated by <span class="hlt">hydrate</span> and the three-phase system remains stable within the pore space of sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19569226','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19569226"><span>Crystallization of a polymorphic <span class="hlt">hydrate</span> system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tian, F; Qu, H; Louhi-Kultanen, M; Rantanen, J</p> <p>2010-02-01</p> <p>Nitrofurantoin can form two monohydrates, which have the same chemical composition and molar ratio of water, but differ in the crystal arrangements. The two monohydrates (<span class="hlt">hydrates</span> I and II) could be produced independently via evaporative crystallization, where supersaturation and solvent composition were both found to have an effect. <span class="hlt">Hydrate</span> I showed much slower crystallization than <span class="hlt">hydrate</span> II. During cooling crystallization, the nucleation and growth of <span class="hlt">hydrate</span> II was again dominant, consuming all supersaturation and leading to no <span class="hlt">hydrate</span> I formation. Seeding of <span class="hlt">hydrate</span> I during cooling crystallization was also applied, but the <span class="hlt">hydrate</span> I seeds were not able to initiate its nucleation rather than dissolving into crystallizing solution. Although solubility tests revealed that <span class="hlt">hydrate</span> II is more stable than <span class="hlt">hydrate</span> I due to its lower solubility (110 +/- 4 and 131 +/- 12 microg/mL for <span class="hlt">hydrates</span> II and I, respectively), this difference is rather small. Therefore, the small free energy difference between the two <span class="hlt">hydrates</span>, together with the slow crystallization of <span class="hlt">hydrate</span> I, both lead to a hindrance of <span class="hlt">hydrate</span> I formation. Furthermore, the crystal structure of <span class="hlt">hydrate</span> II demonstrated a higher H-bonding extent than <span class="hlt">hydrate</span> I, suggesting its more favorable crystallization. This is in good agreement with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25785915','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25785915"><span>Micromechanical cohesion force between gas <span class="hlt">hydrate</span> particles measured under high pressure and low temperature conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Bo Ram; Sum, Amadeu K</p> <p>2015-04-07</p> <p>To prevent <span class="hlt">hydrate</span> plugging conditions in the transportation of oil/gas in multiphase flowlines, one of the key processes to control is the agglomeration/deposition of <span class="hlt">hydrate</span> particles, which are determined by the cohesive/adhesive forces. Previous studies reporting measurements of the cohesive/adhesive force between <span class="hlt">hydrate</span> particles used cyclopentane <span class="hlt">hydrate</span> particles in a low-pressure micromechanical force apparatus. In this study, we report the cohesive forces of particles measured in a new high-pressure micromechanical force (MMF) apparatus for ice particles, mixed (methane/ethane, 74.7:25.3) <span class="hlt">hydrate</span> particles (Structure II), and carbon dioxide <span class="hlt">hydrate</span> particles (Structure I). The cohesive forces are measured as a function of the contact <span class="hlt">time</span>, contact force, temperature, and pressure, and determined from pull-off measurements. For the measurements performed of the gas <span class="hlt">hydrate</span> particles in the gas phase, the determined cohesive force is about 30-35 mN/m, about 8 <span class="hlt">times</span> higher than the cohesive force of CyC5 <span class="hlt">hydrates</span> in the liquid CyC5, which is about 4.3 mN/m. We show from our results that the <span class="hlt">hydrate</span> structure (sI with CO2 <span class="hlt">hydrates</span> and sII with CH4/C2H6 <span class="hlt">hydrates</span>) has no influence on the cohesive force. These results are important in the deposition of a gas-dominated system, where the <span class="hlt">hydrate</span> particles formed in the liquid phase can then stick to the <span class="hlt">hydrate</span> deposited in the wall exposed to the gas phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24820852','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24820852"><span>Development of ketoprofen loaded proliposomal <span class="hlt">powders</span> for improved gastric absorption and gastric tolerance: in vitro and in situ evaluation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gangishetty, Himabindu; Eedara, Basanth Babu; Bandari, Suresh</p> <p>2015-01-01</p> <p>The aim of the current investigation was to improve dissolution rate, gastric absorption and tolerance of a water insoluble non-steroidal anti-inflammatory drug ketoprofen by developing proliposomal <span class="hlt">powders</span>. Ketoprofen proliposomal <span class="hlt">powders</span> were prepared by solvent evaporation method with varying ratios of hydrogenated soyphosphatidyl choline (HSPC) and cholesterol. The prepared proliposomal <span class="hlt">powders</span> were characterized for vesicle size, micromeritics, entrapment efficiency and in vitro dissolution behavior. Proliposomal <span class="hlt">powder</span> (KPL3) composed of equimolar ratios of HSPC and cholesterol loaded on pearlitol SD 200 was selected as optimized formulation as it produced smaller liposomes (5.24 ± 1.35 μm) upon <span class="hlt">hydration</span> with highest entrapment efficiency (53.16 ± 0.06%). All proliposomal <span class="hlt">powders</span> showed improved dissolution characteristics than pure drug, however dissolution of drug from KPL3 was found to be highest (91.17 ± 6.3) and which is about 24 <span class="hlt">times</span> higher than pure ketoprofen within 5 min. The transformation of crystalline ketoprofen to amorphous form was confirmed by solid state characterization. The absorption rate per hour for pure ketoprofen and proliposomal formulation (KPL3) was assessed in the stomach by conducting in situ gastric absorption studies in Wistar rats and was found to be 27 ± 1.22 and 36.98 ± 1.95%, respectively. In conclusion, enhanced dissolution and gastric absorption rate of ketoprofen from proliposomal <span class="hlt">powders</span> suggest them as potential candidate for oral bioavailability improvement of ketoprofen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25532338','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25532338"><span>[Identification of pearl <span class="hlt">powder</span> using microscopic infrared reflectance spectroscopy].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Xuan; Hu, Chao; Yan, Yan; Yang, Hai-Feng; Li, Jun-Fang; Bai, Hua; Xi, Guang-Cheng; Liao, Jie</p> <p>2014-09-01</p> <p>Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell <span class="hlt">powders</span> also can be used as medicine; however, its medicinal value is much lower than that of pearl <span class="hlt">powders</span>. Due to the feature similarity between pearl <span class="hlt">powders</span> and shell <span class="hlt">powders</span>, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell <span class="hlt">powders</span> have been often posing as pearl <span class="hlt">powders</span> in markets, which seriously infringes the interests of consumers. Identification of pearl <span class="hlt">powder</span> was investigated by microscopic infrared reflectance spectroscopy, and pearl <span class="hlt">powder</span> as well as shell <span class="hlt">powder</span> was calcined at different temperatures for different <span class="hlt">time</span> before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 °C for 30 minutes under atmospheric pressure, aragonite in pearl <span class="hlt">powder</span> partly transformed into calcite, while aragonite in shell <span class="hlt">powder</span> completely transformed into calcite. At the same <span class="hlt">time</span>, the difference in phase transition between the pearl <span class="hlt">powders</span> 'and shell <span class="hlt">powders</span> can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl <span class="hlt">powder</span> and shell <span class="hlt">powder</span>. It's more meaningfully that the proposed infrared reflectance spec- troscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell <span class="hlt">powders</span> and abalone shell <span class="hlt">powders</span>, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl <span class="hlt">powder</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567929"><span>Airway <span class="hlt">Hydration</span> and COPD</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ghosh, Arunava; Boucher, R.C.; Tarran, Robert</p> <p>2015-01-01</p> <p>Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway <span class="hlt">hydration</span>; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..123a2057K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..123a2057K"><span>Performance Characteristics of Waste Glass <span class="hlt">Powder</span> Substituting Portland Cement in Mortar Mixtures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kara, P.; Csetényi, L. J.; Borosnyói, A.</p> <p>2016-04-01</p> <p>In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine <span class="hlt">powders</span> in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass <span class="hlt">powder</span> at levels of 20% and 30%. Characterisation and testing of waste glass <span class="hlt">powders</span> included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of <span class="hlt">hydration</span> of mortars, temperature of <span class="hlt">hydration</span>, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass <span class="hlt">powder</span> substitution for Portland cement on physical and engineering properties of mortar mixtures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS51B2038C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS51B2038C"><span>Experimental investigations about the effect of trace amount of propane on the formation of mixed <span class="hlt">hydrates</span> of methane and propane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cai, W.; Lu, H.; Huang, X.</p> <p>2016-12-01</p> <p>In natural gas <span class="hlt">hydrates</span>, some heavy hydrocarbons are always detected in addition to methane. However, it is still not well understood how the trace amount of heavy gas affect the <span class="hlt">hydrate</span> properties. Intensive studies have been carried out to study the thermodynamic properties and structure types of mixed gases <span class="hlt">hydrates</span>, but comparatively few investigations have been carried out on the cage occupancies of guest molecules in mixed gases <span class="hlt">hydrates</span>. For understanding how trace amount of propane affects the formation of mixed methane-propane <span class="hlt">hydrates</span>, X-ray diffraction, Raman spectroscopy, and gas chromatography were applied to the synthesized mixed methane-propane <span class="hlt">hydrate</span> specimens, to get their structural characteristics (structure type, structural parameters, cage occupancy, etc.) and gas compositions. The mixed methane-propane <span class="hlt">hydrates</span> were prepared by reacting fine ice <span class="hlt">powders</span> with various gas mixtures of methane and propane. When the propane content was below 0.4%, the <span class="hlt">hydrates</span> synthesized were found containing both sI methane <span class="hlt">hydrate</span> and sII methane-propane <span class="hlt">hydrate</span>; while the <span class="hlt">hydrates</span> were found always sII when propane was over certain content. Detail studies about the cage occupancies of propane and methane in sII <span class="hlt">hydrate</span> revealed that: 1) with the increase in propane content of methane-propane mixture, the occupancy of propane in large cage increased as accompanied with the decrease in methane occupancy in large cage, however the occupancy of methane in small cage didn't experience significant change; 2) temperature and pressure seemed no obvious influence on cage occupancy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20871545','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20871545"><span>Crystal structure refinement and <span class="hlt">hydration</span> behaviour of doped tricalcium aluminate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stephan, Dietmar . E-mail: dietmar.stephan@online.de; Wistuba, Sebastian</p> <p>2006-11-15</p> <p>In this paper analytical evidence on crystal structure and <span class="hlt">hydration</span> behaviour of C{sub 3}A solid solutions with MgO, SiO{sub 2}, Fe{sub 2}O{sub 3}, Na{sub 2}O and K{sub 2}O is given. Samples were prepared using an innovative sol-gel process as precursor, examined by X-ray <span class="hlt">powder</span> diffraction, infra-red spectroscopy and the crystal structure was refined by the Rietveld method. A significant shift of lattice parameters was found for C{sub 3}A solid solutions with SiO{sub 2}, Fe{sub 2}O{sub 3} or Na{sub 2}O but only minor changes were detected for K{sub 2}O. The <span class="hlt">hydration</span> of C{sub 3}A solid solutions in the absence of CaSO{sub 4} was accelerated for samples doped with SiO{sub 2} or K{sub 2}O and it was retarded in the case of MgO, Fe{sub 2}O{sub 3} or Na{sub 2}O. The <span class="hlt">hydration</span> in the presence of CaSO{sub 4} was accelerated when C{sub 3}A was doped with K{sub 2}O or Na{sub 2}O, whereas Fe{sub 2}O{sub 3} strongly retarded the <span class="hlt">hydration</span>. The doping with SiO{sub 2} nearly had no influence on the <span class="hlt">hydration</span>, the effect of MgO was not straight forward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/121743','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/121743"><span>Natural gas <span class="hlt">hydrate</span> occurrence and issues: Large amounts of methane in gas <span class="hlt">hydrates</span> are potential energy sources; role in climate change?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kvenvolden, K.</p> <p>1995-09-01</p> <p>Naturally occurring gas <span class="hlt">hydrate</span> is a solid, icelike substance composed of rigid cages of water molecules that enclose molecules of gas, mainly methane. Chemically, this substance is a water clathrate of methane, often called methane clathrate, in addition to methane <span class="hlt">hydrate</span> or gas <span class="hlt">hydrate</span>. In an ideally saturated methane <span class="hlt">hydrate</span>, the molar ratio of methane to water is 1:5.75, that is, equal to a volumetric ratio at standard conditions of about 164:1. Gas <span class="hlt">hydrate</span> deposits aaoccur under specific conditions of pressure and temperature, where the supply of methane is sufficient to initiate and stabilize the <span class="hlt">hydrate</span> structure. These conditions are met on Earth in shallow sediment, less than 2,000 meters deep in two regions: (1) continental, including continental shelves at high latitudes where surface temperatures are very cold, and (2) submarine continental slopes and rises where not only is the bottom water cold but also pressures are very high. Thus in polar regions, gas <span class="hlt">hydrate</span> is found where temperatures are cold enough for onshore and offshore permafrost to be present. During global warming, deep sea gas <span class="hlt">hydrates</span> become more stable, but gas <span class="hlt">hydrate</span> of polar continents and continental shelves is destabilized, leading to methane release over long <span class="hlt">time</span> scales. Methane reaching the atmosphere from these sources contributes to the global warming trend. During a global cooling cycle, the whole system reverses. Methodologies are being developed to recover methane from this substance. Three principal methods are being considered: thermal stimulation, depressurization, and inhibitor injection.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4296306','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4296306"><span>A mild alkali treated jute fibre controlling the <span class="hlt">hydration</span> behaviour of greener cement paste</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jo, Byung-Wan; Chakraborty, Sumit</p> <p>2015-01-01</p> <p>To reduce the antagonistic effect of jute fibre on the setting and <span class="hlt">hydration</span> of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and <span class="hlt">hydration</span> behaviour of cement. Setting <span class="hlt">time</span> measurement, <span class="hlt">hydration</span> test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the <span class="hlt">hydration</span> test, the <span class="hlt">time</span> (t) required to reach maximum temperature for the <span class="hlt">hydration</span> of control cement sample is estimated to be 860 min, whilst the <span class="hlt">time</span> (t) is measured to be 1040 min for the <span class="hlt">hydration</span> of a raw jute reinforced cement sample. However, the <span class="hlt">time</span> (t) is estimated to be 1020 min for the <span class="hlt">hydration</span> of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and <span class="hlt">hydration</span> delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and <span class="hlt">hydration</span> behaviour of alkali treated jute fibre reinforced cement composite. PMID:25592665</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E7837J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E7837J"><span>A mild alkali treated jute fibre controlling the <span class="hlt">hydration</span> behaviour of greener cement paste</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jo, Byung-Wan; Chakraborty, Sumit</p> <p>2015-01-01</p> <p>To reduce the antagonistic effect of jute fibre on the setting and <span class="hlt">hydration</span> of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and <span class="hlt">hydration</span> behaviour of cement. Setting <span class="hlt">time</span> measurement, <span class="hlt">hydration</span> test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the <span class="hlt">hydration</span> test, the <span class="hlt">time</span> (t) required to reach maximum temperature for the <span class="hlt">hydration</span> of control cement sample is estimated to be 860 min, whilst the <span class="hlt">time</span> (t) is measured to be 1040 min for the <span class="hlt">hydration</span> of a raw jute reinforced cement sample. However, the <span class="hlt">time</span> (t) is estimated to be 1020 min for the <span class="hlt">hydration</span> of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and <span class="hlt">hydration</span> delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and <span class="hlt">hydration</span> behaviour of alkali treated jute fibre reinforced cement composite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25592665','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25592665"><span>A mild alkali treated jute fibre controlling the <span class="hlt">hydration</span> behaviour of greener cement paste.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jo, Byung-Wan; Chakraborty, Sumit</p> <p>2015-01-16</p> <p>To reduce the antagonistic effect of jute fibre on the setting and <span class="hlt">hydration</span> of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and <span class="hlt">hydration</span> behaviour of cement. Setting <span class="hlt">time</span> measurement, <span class="hlt">hydration</span> test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the <span class="hlt">hydration</span> test, the <span class="hlt">time</span> (t) required to reach maximum temperature for the <span class="hlt">hydration</span> of control cement sample is estimated to be 860 min, whilst the <span class="hlt">time</span> (t) is measured to be 1040 min for the <span class="hlt">hydration</span> of a raw jute reinforced cement sample. However, the <span class="hlt">time</span> (t) is estimated to be 1020 min for the <span class="hlt">hydration</span> of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and <span class="hlt">hydration</span> delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and <span class="hlt">hydration</span> behaviour of alkali treated jute fibre reinforced cement composite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1242024','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1242024"><span>Nucleation Rate Analysis of Methane <span class="hlt">Hydrate</span> from Molecular Dynamics Simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yuhara, Daisuke; Barnes, Brian C.; Suh, Donguk; Knott, Brandon C.; Beckham, Gregg T.; Yasuoka, Kenji; Wu, David T.; Amadeu K. Sum</p> <p>2015-01-06</p> <p>Clathrate <span class="hlt">hydrates</span> are solid crystalline structures most commonly formed from solutions that have nucleated to form a mixed solid composed of water and gas. Understanding the mechanism of clathrate <span class="hlt">hydrate</span> nucleation is essential to grasp the fundamental chemistry of these complex structures and their applications. Molecular dynamics (MD) simulation is an ideal method to study nucleation at the molecular level because the size of the critical nucleus and formation rate occur on the nano scale. Moreover, various analysis methods for nucleation have been developed through MD to analyze nucleation. In particular, the mean first-passage <span class="hlt">time</span> (MFPT) and survival probability (SP) methods have proven to be effective in procuring the nucleation rate and critical nucleus size for monatomic systems. This study assesses the MFPT and SP methods, previously used for monatomic systems, when applied to analyzing clathrate <span class="hlt">hydrate</span> nucleation. Because clathrate <span class="hlt">hydrate</span> nucleation is relatively difficult to observe in MD simulations (due to its high free energy barrier), these methods have yet to be applied to clathrate <span class="hlt">hydrate</span> systems. In this study, we have analyzed the nucleation rate and critical nucleus size of methane <span class="hlt">hydrate</span> using MFPT and SP methods from data generated by MD simulations at 255 K and 50 MPa. MFPT was modified for clathrate <span class="hlt">hydrate</span> from the original version by adding the maximum likelihood estimate and growth effect term. The nucleation rates were calculated by MFPT and SP methods and are within 5%; the critical nucleus size estimated by the MFPT method was 50% higher, than values obtained through other more rigorous but computationally expensive estimates. These methods can also be extended to the analysis of other clathrate <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1242024-nucleation-rate-analysis-methane-hydrate-from-molecular-dynamics-simulations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1242024-nucleation-rate-analysis-methane-hydrate-from-molecular-dynamics-simulations"><span>Nucleation Rate Analysis of Methane <span class="hlt">Hydrate</span> from Molecular Dynamics Simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yuhara, Daisuke; Barnes, Brian C.; Suh, Donguk; ...</p> <p>2015-01-06</p> <p>Clathrate <span class="hlt">hydrates</span> are solid crystalline structures most commonly formed from solutions that have nucleated to form a mixed solid composed of water and gas. Understanding the mechanism of clathrate <span class="hlt">hydrate</span> nucleation is essential to grasp the fundamental chemistry of these complex structures and their applications. Molecular dynamics (MD) simulation is an ideal method to study nucleation at the molecular level because the size of the critical nucleus and formation rate occur on the nano scale. Moreover, various analysis methods for nucleation have been developed through MD to analyze nucleation. In particular, the mean first-passage <span class="hlt">time</span> (MFPT) and survival probability (SP)more » methods have proven to be effective in procuring the nucleation rate and critical nucleus size for monatomic systems. This study assesses the MFPT and SP methods, previously used for monatomic systems, when applied to analyzing clathrate <span class="hlt">hydrate</span> nucleation. Because clathrate <span class="hlt">hydrate</span> nucleation is relatively difficult to observe in MD simulations (due to its high free energy barrier), these methods have yet to be applied to clathrate <span class="hlt">hydrate</span> systems. In this study, we have analyzed the nucleation rate and critical nucleus size of methane <span class="hlt">hydrate</span> using MFPT and SP methods from data generated by MD simulations at 255 K and 50 MPa. MFPT was modified for clathrate <span class="hlt">hydrate</span> from the original version by adding the maximum likelihood estimate and growth effect term. The nucleation rates were calculated by MFPT and SP methods and are within 5%; the critical nucleus size estimated by the MFPT method was 50% higher, than values obtained through other more rigorous but computationally expensive estimates. These methods can also be extended to the analysis of other clathrate <span class="hlt">hydrates</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25876773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25876773"><span>Nucleation rate analysis of methane <span class="hlt">hydrate</span> from molecular dynamics simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yuhara, Daisuke; Barnes, Brian C; Suh, Donguk; Knott, Brandon C; Beckham, Gregg T; Yasuoka, Kenji; Wu, David T; Sum, Amadeu K</p> <p>2015-01-01</p> <p>Clathrate <span class="hlt">hydrates</span> are solid crystalline structures most commonly formed from solutions that have nucleated to form a mixed solid composed of water and gas. Understanding the mechanism of clathrate <span class="hlt">hydrate</span> nucleation is essential to grasp the fundamental chemistry of these complex structures and their applications. Molecular dynamics (MD) simulation is an ideal method to study nucleation at the molecular level because the size of the critical nucleus and formation rate occur on the nano scale. Various analysis methods for nucleation have been developed through MD to analyze nucleation. In particular, the mean first-passage <span class="hlt">time</span> (MFPT) and survival probability (SP) methods have proven to be effective in procuring the nucleation rate and critical nucleus size for monatomic systems. This study assesses the MFPT and SP methods, previously used for monatomic systems, when applied to analyzing clathrate <span class="hlt">hydrate</span> nucleation. Because clathrate <span class="hlt">hydrate</span> nucleation is relatively difficult to observe in MD simulations (due to its high free energy barrier), these methods have yet to be applied to clathrate <span class="hlt">hydrate</span> systems. In this study, we have analyzed the nucleation rate and critical nucleus size of methane <span class="hlt">hydrate</span> using MFPT and SP methods from data generated by MD simulations at 255 K and 50 MPa. MFPT was modified for clathrate <span class="hlt">hydrate</span> from the original version by adding the maximum likelihood estimate and growth effect term. The nucleation rates calculated by MFPT and SP methods are within 5%, and the critical nucleus size estimated by the MFPT method was 50% higher, than values obtained through other more rigorous but computationally expensive estimates. These methods can also be extended to the analysis of other clathrate <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873875','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873875"><span>Multiple feed <span class="hlt">powder</span> splitter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lewis, Gary K.; Less, Richard M.</p> <p>2001-01-01</p> <p>A device for providing uniform <span class="hlt">powder</span> flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained <span class="hlt">powders</span> are passed through the focal point of a moving high-power laser light which fuses the particles in the <span class="hlt">powder</span> to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained <span class="hlt">powders</span> to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained <span class="hlt">powder</span> from between one to four hoppers and split the flow into eight tubular lines which feed the <span class="hlt">powder</span> delivery nozzles of the DLF system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/874575','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/874575"><span>Multiple feed <span class="hlt">powder</span> splitter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lewis, Gary K.; Less, Richard M.</p> <p>2002-01-01</p> <p>A device for providing uniform <span class="hlt">powder</span> flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained <span class="hlt">powders</span> are passed through the focal point of a moving high-power laser light which fuses the particles in the <span class="hlt">powder</span> to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained <span class="hlt">powders</span> to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained <span class="hlt">powder</span> from between one to four hoppers and split the flow into eight tubular lines which feed the <span class="hlt">powder</span> delivery nozzles of the DLF system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1289917','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1289917"><span>Granulation of fine <span class="hlt">powder</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chen, Ching-Fong</p> <p>2016-08-09</p> <p>A mixture of fine <span class="hlt">powder</span> including thorium oxide was converted to granulated <span class="hlt">powder</span> by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated <span class="hlt">powder</span> was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated <span class="hlt">powder</span> relies on the thermal bonding to maintain its shape and structure. The granulated <span class="hlt">powder</span> contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated <span class="hlt">powder</span> was pressed and sintered to form a dense compact with a higher density and more uniform pore size distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11559134','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11559134"><span>alpha-Terpineol from <span class="hlt">hydration</span> of crude sulfate turpentine oil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pakdel, H; Sarron, S; Roy, C</p> <p>2001-09-01</p> <p><span class="hlt">Hydration</span> of alpha-pinene under various conditions was studied and compared with the literature. Optimal reaction conditions have been established for the <span class="hlt">hydration</span> of alpha-pinene and crude turpentine oil in the absence of catalyst and using a low volume of acetone. A detailed reaction product analysis is reported. The main <span class="hlt">hydration</span> product, alpha-terpineol, was obtained at a yield of 67 wt % of the initial alpha-pinene by reacting with 15% aqueous sulfuric acid and an excess of acetone in an oil bath heated to 80-85 degrees C over the course of 4 h. A progressive transformation of alpha-terpineol to 4-(2-hydroxypropyl)-1-methylcyclohexanol (1,8-terpine) takes place as the <span class="hlt">hydration</span> <span class="hlt">time</span> exceeds 4 h. A crude turpentine oil sample was also <span class="hlt">hydrated</span> under conditions similar to those of alpha-pinene. The alpha-terpineol yield was 77 wt % of the initial alpha-pinene in the crude turpentine oil. The chemical analysis of the crude turpentine oil before and after <span class="hlt">hydration</span> was carried out, and the distribution of the products was discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4506896','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4506896"><span>Impact of <span class="hlt">Hydration</span> Media on Ex Vivo Corneal Elasticity Measurements</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dias, Janice; Ziebarth, Noël M.</p> <p>2014-01-01</p> <p>Objectives To determine the effect of <span class="hlt">hydration</span> media on ex vivo corneal elasticity. Methods Experiments were conducted on forty porcine eyes retrieved from an abattoir (10 eyes each for PBS, BSS, Optisol, 15% Dextran). The epithelium was removed and the cornea was excised with an intact scleral rim and placed in 20% Dextran overnight to restore its physiological thickness. For each <span class="hlt">hydration</span> media, corneas were evenly divided into two groups: one with an intact scleral rim and the other without. Corneas were mounted onto a custom chamber and immersed in a <span class="hlt">hydration</span> medium for elasticity testing. While in each medium, corneal elasticity measurements were performed for 2 hours: at 5-minute intervals for the first 30 minutes and then 15-minute intervals for the remaining 90 minutes. Elasticity testing was performed using nanoindentation with spherical indenters and Young’s modulus was calculated using the Hertz model. Thickness measurements were taken before and after elasticity testing. Results The percentage change in corneal thickness and elasticity was calculated for each <span class="hlt">hydration</span> media group. BSS, PBS, and Optisol showed an increase in thickness and Young’s moduli for corneas with and without an intact scleral rim. 15% Dextran exhibited a dehydrating effect on corneal thickness and provided stable maintenance of corneal elasticity for both groups. Conclusions <span class="hlt">Hydration</span> media affects the stability of corneal thickness and elasticity measurements over <span class="hlt">time</span>. 15% Dextran was most effective in maintaining corneal <span class="hlt">hydration</span> and elasticity, followed by Optisol. PMID:25603443</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B13B0624K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B13B0624K"><span>Development of Sand Production Evaluation Apparatus for Methane <span class="hlt">Hydrate</span> Development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kakumoto, M.; Yoneda, J.; Tenma, N.; Katagiri, J.; Noda, S.</p> <p>2015-12-01</p> <p>As a part of a Japanese National <span class="hlt">hydrate</span> research program (MH21, funded by METI), we performed a study on sand production mechanism during methane gas production. In 2013, the first methane <span class="hlt">hydrate</span> offshore production test was conducted in Japan, and it was recognized in the production of about 20000m3/day of methane gas from methane <span class="hlt">hydrate</span> bearing sand sediment in deep marine sediment. In methane <span class="hlt">hydrate</span> development, depressurization method has been proposed for gas extraction. This method is a method to reduce the bottom hole pressure by submersible pump lowering water level in the production well, and gas and water is recovered by methane <span class="hlt">hydrate</span> dissociation at the in situ. At that <span class="hlt">time</span>, a phenomenon that sand flows into the wells is feared. In actually, sand production phenomenon occurred after 6 days from production start in offshore production test. A mechanism of sand production has not yet been resolved in case of methane <span class="hlt">hydrate</span> development. Therefore, we developed large scale laboratory test apparatus for the purpose of elucidation of the mechanism of sand production phenomenon. In this presentation, we introduce basic performance of this apparatus, and usefulness is made mention by representative test results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25325376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25325376"><span><span class="hlt">Hydration</span> control of the mechanical and dynamical properties of cellulose.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Petridis, Loukas; O'Neill, Hugh M; Johnsen, Mariah; Fan, Bingxin; Schulz, Roland; Mamontov, Eugene; Maranas, Janna; Langan, Paul; Smith, Jeremy C</p> <p>2014-11-10</p> <p>The mechanical and dynamical properties of cellulose, the most abundant biomolecule on earth, are essential for its function in plant cell walls and advanced biomaterials. Cellulose is almost always found in a <span class="hlt">hydrated</span> state, and it is therefore important to understand how <span class="hlt">hydration</span> influences its dynamics and mechanics. Here, the nanosecond-<span class="hlt">time</span> scale dynamics of cellulose is characterized using dynamic neutron scattering experiments and molecular dynamics (MD) simulation. The experiments reveal that <span class="hlt">hydrated</span> samples exhibit a higher average mean-square displacement above ∼240 K. The MD simulation reveals that the fluctuations of the surface hydroxymethyl atoms determine the experimental temperature and <span class="hlt">hydration</span> dependence. The increase in the conformational disorder of the surface hydroxymethyl groups with temperature follows the cellulose persistence length, suggesting a coupling between structural and mechanical properties of the biopolymer. In the MD simulation, 20% <span class="hlt">hydrated</span> cellulose is more rigid than the dry form, due to more closely packed cellulose chains and water molecules bridging cellulose monomers with hydrogen bonds. This finding may have implications for understanding the origin of strength and rigidity of secondary plant cell walls. The detailed characterization obtained here describes how <span class="hlt">hydration</span>-dependent increased fluctuations and hydroxymethyl disorder at the cellulose surface lead to enhancement of the rigidity of this important biomolecule.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B13B0626S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B13B0626S"><span>Determination of the Physical Properties of Sediments Depending on <span class="hlt">Hydrate</span> Saturation Using a "Quick Look" Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strauch, B.; Schicks, J. M.; Spangenberg, E.; Seyberth, K.; Heeschen, K. U.; Priegnitz, M.</p> <p>2015-12-01</p> <p>Seismic and electromagnetic measurements are promising tools for the detection and quantification of gas <span class="hlt">hydrate</span> occurrences in nature. The seismic wave velocity depends among others on the <span class="hlt">hydrate</span> quantity and the quality (e.g. pore filling or cementing <span class="hlt">hydrate</span>). For a proper interpretation of seismic data the knowledge of the dependency of physical properties as a function of <span class="hlt">hydrate</span> saturation in a certain scenario is crucial. Within the SUGAR III project we determine such dependencies for various scenarios to support models for joint inversion of seismic and EM data e.g. for the shallow gas <span class="hlt">hydrate</span> reservoirs in the Danube Delta. Since the formation of artificial lab samples containing pore filling <span class="hlt">hydrate</span> from methane dissolved in water is a complex and <span class="hlt">time</span> consuming procedure, we developed an easier alternative. Ice is very similar to <span class="hlt">hydrate</span> in some of its physical properties. Therefore it might be used as analogous pore fill in a "quick look" experiment to determine the dependency of rock physical properties on <span class="hlt">hydrate</span> content. We used the freezing point depression of a KCl solution to generate a dependency of ice saturation on temperature. The measured seismic wave velocity in dependence on ice saturation compares very well with data measured on a glass bead sediment sample with methane <span class="hlt">hydrate</span> formed from methane dissolved in water. We could also observe that ice, formed from a salt solution in the pore space of sediment, behaves similar to methane <span class="hlt">hydrate</span> as a non-cementing solid pore fill.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1060701','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1060701"><span>Experimental and Numerical Observations of <span class="hlt">Hydrate</span> Reformation during Depressurization in a Core-Scale Reactor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Seol, Yongkoo; Myshakin, Evgeniy</p> <p>2011-01-01</p> <p>Gas <span class="hlt">hydrate</span> has been predicted to reform around a wellbore during depressurization-based gas production from gas <span class="hlt">hydrate</span>-bearing reservoirs. This process has an adverse effect on gas production rates and it requires <span class="hlt">time</span> and sometimes special measures to resume gas flow to producing wells. Due to lack of applicable field data, laboratory scale experiments remain a valuable source of information to study <span class="hlt">hydrate</span> reformation. In this work, we report laboratory experiments and complementary numerical simulations executed to investigate the <span class="hlt">hydrate</span> reformation phenomenon. Gas production from a pressure vessel filled with <span class="hlt">hydrate</span>-bearing sand was induced by depressurization with and without heat flux through the boundaries. <span class="hlt">Hydrate</span> decomposition was monitored with a medical X-ray CT scanner and pressure and temperature measurements. CT images of the <span class="hlt">hydrate</span>-bearing sample were processed to provide 3-dimensional data of heterogeneous porosity and phase saturations suitable for numerical simulations. In the experiments, gas <span class="hlt">hydrate</span> reformation was observed only in the case of no-heat supply from surroundings, a finding consistent with numerical simulation. By allowing gas production on either side of the core, numerical simulations showed that initial <span class="hlt">hydrate</span> distribution patterns affect gas distribution and flow inside the sample. This is a direct consequence of the heterogeneous pore network resulting in varying hydraulic properties of the <span class="hlt">hydrate</span>-bearing sediment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25903085','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25903085"><span>Water-wetting surfaces as <span class="hlt">hydrate</span> promoters during transport of carbon dioxide with impurities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kuznetsova, Tatiana; Jensen, Bjørnar; Kvamme, Bjørn; Sjøblom, Sara</p> <p>2015-05-21</p> <p>Water condensing as liquid drops within the fluid bulk has traditionally been the only scenario accepted in the industrial analysis of <span class="hlt">hydrate</span> risks. We have applied a combination of absolute thermodynamics and molecular dynamics modeling to analyze the five primary routes of <span class="hlt">hydrate</span> formation in a rusty pipeline carrying dense carbon dioxide with methane, hydrogen sulfide, argon, and nitrogen as additional impurities. We have revised the risk analysis of all possible routes in accordance with the combination of the first and the second laws of thermodynamics to determine the highest permissible content of water. It was found that at concentrations lower than five percent, hydrogen sulfide will only support the formation of carbon dioxide-dominated <span class="hlt">hydrate</span> from adsorbed water and <span class="hlt">hydrate</span> formers from carbon dioxide phase rather than formation in the aqueous phase. Our results indicate that hydrogen sulfide leaving carbon dioxide for the aqueous phase will be able to create an additional <span class="hlt">hydrate</span> phase in the aqueous region adjacent to the first adsorbed water layer. The growth of <span class="hlt">hydrate</span> from different phases will decrease the induction <span class="hlt">time</span> by substantially reducing the kinetically limiting mass transport across the <span class="hlt">hydrate</span> films. <span class="hlt">Hydrate</span> formation via adsorption of water on rusty walls will play the decisive role in <span class="hlt">hydrate</span> formation risk, with the initial concentration of hydrogen sulfide being the critical factor. We concluded that the safest way to eliminate <span class="hlt">hydrate</span> risks is to ensure that the water content of carbon dioxide is low enough to prevent water dropout via the adsorption mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26730123','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26730123"><span>Cow dung <span class="hlt">powder</span> poisoning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sherfudeen, Khaja Mohideen; Kaliannan, Senthil Kumar; Dammalapati, Pavan Kumar</p> <p>2015-11-01</p> <p>Cow dung, which has germicidal property, was used in ancient days to clean living premises in South India. Nowadays, people are using commercially available synthetic cow dung <span class="hlt">powder</span>. It is locally known as "saani <span class="hlt">powder</span>" in Tamil Nadu. It is freely available in homes and is sometimes accidentally consumed by children. It is available in two colors - yellow and green. Cow dung <span class="hlt">powder</span> poisoning is common in districts of Tamil Nadu such as Coimbatore, Tirupur, and Erode. We report two cases of yellow cow dung <span class="hlt">powder</span> poisoning from our hospital.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMOS41A..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMOS41A..08H"><span><span class="hlt">Hydrate</span> Formation in Gas-Rich Marine Sediments: A Grain-Scale Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holtzman, R.; Juanes, R.</p> <p>2009-12-01</p> <p>We present a grain-scale model of marine sediment, which couples solid- and multiphase fluid-mechanics together with <span class="hlt">hydrate</span> kinetics. The model is applied to investigate the spatial distribution of the different methane phases - gas and <span class="hlt">hydrate</span> - within the <span class="hlt">hydrate</span> stability zone. Sediment samples are generated from three-dimensional packs of spherical grains, mapping the void space into a pore network by tessellation. Gas invasion into the water-saturated sample is simulated by invasion-percolation, coupled with a discrete element method that resolves the grain mechanics. The coupled model accounts for forces exerted by the fluids, including cohesion associated with gas-brine surface tension. <span class="hlt">Hydrate</span> growth is represented by a <span class="hlt">hydrate</span> film along the gas-brine interface, which increases sediment cohesion by cementing the grain contacts. Our model of <span class="hlt">hydrate</span> growth includes the possible rupture of the <span class="hlt">hydrate</span> layer, which leads to the creation of new gas-water interface. In previous work, we have shown that fine-grained sediments (FGS) exhibit greater tendency to fracture, whereas capillary invasion is the preferred mode of methane gas transport in coarse-grained sediments (CGS). The gas invasion pattern has profound consequences on the <span class="hlt">hydrate</span> distribution: a larger area-to-volume ratio of the gas cluster leads to a larger drop in gas pressure inside the growing <span class="hlt">hydrate</span> shell, causing it to rupture. Repeated cycles of imbibition and <span class="hlt">hydrate</span> growth accompanied by trapping of gas allow us to determine the distribution of <span class="hlt">hydrate</span> and gas within the sediment as a function of <span class="hlt">time</span>. Our pore-scale model suggests that, even when film rupture takes place, the conversion of gas to <span class="hlt">hydrate</span> is slow. This explains two common field observations: the coexistence of gas and <span class="hlt">hydrate</span> within the <span class="hlt">hydrate</span> stability zone in CGS, and the high methane fluxes through fracture conduits in FGS. These results demonstrate the importance of accounting for the strong coupling among multiphase</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/549167','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/549167"><span>Distribution and controls on gas <span class="hlt">hydrate</span> in the ocean-floor environment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dillon, W.P.</p> <p>1995-12-31</p> <p>Methane <span class="hlt">hydrate</span>, a crystalline solid that is formed of water and gas molecules, is widespread in oceanic sediments. It occurs at water depths that exceed 300 to 500 m and in a zone that commonly extends from the sea floor, down several hundred meters - the base of the zone is limited by increased temperature. To determine factors that control gas <span class="hlt">hydrate</span> concentration, we have mapped its distribution off the U.S. Atlantic coast using acoustic remote-sensing methods. Most natural gas <span class="hlt">hydrate</span> is formed from biogenic methane, and therefore it is concentrated where there is a rapid accumulation of organic detritus and also where there is a rapid accumulation of sediments (which protect detritus from oxidation). When <span class="hlt">hydrate</span> fills the pore space of sediment, it can reduce permeability and create a gas trap. Such trapping of gas beneath <span class="hlt">hydrate</span> may cause the formation of the most concentrated <span class="hlt">hydrate</span> deposits, perhaps because the gas that is held in the trap can slowly diffuse upwards or migrate through faults. <span class="hlt">Hydrate</span>-sealed traps are formed by hills on the sea floor, by dipping strata, or by salt(?) domes. Off the southeastern United States, a small area (only 3000 km{sup 2}) beneath a ridge formed by rapidly-deposited sediments appears to contain a volume of methane in <span class="hlt">hydrate</span> that is equivalent to {approximately}30 <span class="hlt">times</span> the U.S. annual consumption of gas. The breakdown of <span class="hlt">hydrate</span> can cause submarine landslides by converting the <span class="hlt">hydrate</span> to gas plus water and generating a rise of pore pressure. Conversely, sea-floor landslides can cause breakdown of <span class="hlt">hydrate</span> by reducing the pressure in sediments. These interacting processes may cause cascading slides, which would result in breakdown of <span class="hlt">hydrate</span> and release of methane to the atmosphere. This addition of methane to the global greenhouse would significantly influence climate. Gas <span class="hlt">hydrate</span> in sea-floor sediments is potentially significant to climate, energy resources, and sea-floor stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS42A..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS42A..04M"><span>Basin-Wide Temperature Constraints On Gas <span class="hlt">Hydrate</span> Stability In The Gulf Of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacDonald, I. R.; Reagan, M. T.; Guinasso, N. L.; Garcia-Pineda, O. G.</p> <p>2012-12-01</p> <p>Gas <span class="hlt">hydrate</span> deposits commonly occur at the seafloor-water interface on marine margins. They are especially prevalent in the Gulf of Mexico where they are associated with natural oil seeps. The stability of these deposits is potentially challenged by fluctuations in bottom water temperature, on an annual <span class="hlt">time</span>-scale, and under the long-term influence of climate change. We mapped the locations of natural oil seeps where shallow gas <span class="hlt">hydrate</span> deposits are known to occur across the entire Gulf of Mexico basin based on a comprehensive review of synthetic aperture radar (SAR) data (~200 images). We prepared a bottom water temperature map based on the archive of CTD casts from the Gulf (~6000 records). Comparing the distribution of gas <span class="hlt">hydrate</span> deposits with predicted bottom water temperature, we find that a broad area of the upper slope lies above the theoretical stability horizon for structure 1 gas <span class="hlt">hydrate</span>, while all sites where gas <span class="hlt">hydrate</span> deposits occur are within the stability horizon for structure 2 gas <span class="hlt">hydrate</span>. This is consistent with analytical results that structure 2 gas <span class="hlt">hydrates</span> predominate on the upper slope (Klapp et al., 2010), where bottom water temperatures fluctuate over a 7 to 10 C range (approx. 600 m depth), while pure structure 1 <span class="hlt">hydrates</span> are found at greater depths (approx. 3000 m). Where higher hydrocarbon gases are available, formation of structure 2 gas <span class="hlt">hydrate</span> should significantly increase the resistance of shallow gas <span class="hlt">hydrate</span> deposits to destabilizing effects variable or increasing bottom water temperature. Klapp, S.A., Bohrmann, G., Kuhs, W.F., Murshed, M.M., Pape, T., Klein, H., Techmer, K.S., Heeschen, K.U., and Abegg, F., 2010, Microstructures of structure I and II gas <span class="hlt">hydrates</span> from the Gulf of Mexico: Marine and Petroleum Geology, v. 27, p. 116-125.Bottom temperature and pressure for Gulf of Mexico gas <span class="hlt">hydrate</span> outcrops and stability horizons for sI and sII <span class="hlt">hydrate</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024086','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024086"><span>Energy resource potential of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, T.S.</p> <p>2002-01-01</p> <p>The discovery of large gas <span class="hlt">hydrate</span> accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans has heightened interest in gas <span class="hlt">hydrates</span> as a possible energy resource. However, significant to potentially insurmountable technical issues must be resolved before gas <span class="hlt">hydrates</span> can be considered a viable option for affordable supplies of natural gas. The combined information from Arctic gas <span class="hlt">hydrate</span> studies shows that, in permafrost regions, gas <span class="hlt">hydrates</span> may exist at subsurface depths ranging from about 130 to 2000 m. The presence of gas <span class="hlt">hydrates</span> in offshore continental margins has been inferred mainly from anomalous seismic reflectors, known as bottom-simulating reflectors, that have been mapped at depths below the sea floor ranging from about 100 to 1100 m. Current estimates of the amount of gas in the world's marine and permafrost gas <span class="hlt">hydrate</span> accumulations are in rough accord at about 20,000 trillion m3. Disagreements over fundamental issues such as the volume of gas stored within delineated gas <span class="hlt">hydrate</span> accumulations and the concentration of gas <span class="hlt">hydrates</span> within <span class="hlt">hydrate</span>-bearing strata have demonstrated that we know little about gas <span class="hlt">hydrates</span>. Recently, however, several countries, including Japan, India, and the United States, have launched ambitious national projects to further examine the resource potential of gas <span class="hlt">hydrates</span>. These projects may help answer key questions dealing with the properties of gas <span class="hlt">hydrate</span> reservoirs, the design of production systems, and, most important, the costs and economics of gas <span class="hlt">hydrate</span> production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1174427','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1174427"><span>Biaxially textured articles formed by <span class="hlt">powder</span> metallurgy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.</p> <p>2003-08-05</p> <p>A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered <span class="hlt">powder</span>-metallurgy preform article, the preform article having been formed from a <span class="hlt">powder</span> mixture selected from the group of ternary mixtures consisting of: Ni <span class="hlt">powder</span>, Cu <span class="hlt">powder</span>, and Al <span class="hlt">powder</span>, Ni <span class="hlt">powder</span>, Cr <span class="hlt">powder</span>, and Al <span class="hlt">powder</span>; Ni <span class="hlt">powder</span>, W <span class="hlt">powder</span> and Al <span class="hlt">powder</span>; Ni <span class="hlt">powder</span>, V <span class="hlt">powder</span>, and Al <span class="hlt">powder</span>; Ni <span class="hlt">powder</span>, Mo <span class="hlt">powder</span>, and Al <span class="hlt">powder</span>; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/890694','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/890694"><span>Depressurization-induced gas production from Class 1 and Class 2<span class="hlt">hydrate</span> deposits</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moridis, George J.; Kowalsky, Michael</p> <p>2006-05-12</p> <p>Class 1 <span class="hlt">hydrate</span> deposits are characterized by aHy-drate-Bearing Layer (HBL) underlain by a two-phase zone involvingmobile gas. Such deposits are further divided to Class 1W (involvingwater and <span class="hlt">hydrate</span> in the HBL) and Class 1G (involving gas and <span class="hlt">hydrate</span> inthe HBL). In Class 2 deposits, a mobile water zone underlies the hydratezone. Methane is the main <span class="hlt">hydrate</span>-forming gas in natural accumulations.Using TOUGH-FX/<span class="hlt">HYDRATE</span> to study the depressurization-induced gasproduction from such deposits, we determine that large volumes of gascould be readily produced at high rates for long <span class="hlt">times</span> using conventionaltechnology. Dissociation in Class 1W deposits proceeds in distinctstages, but is continuous in Class 1G deposits. <span class="hlt">Hydrates</span> are shown tocontribute significantly to the production rate (up to 65 percent and 75percent in Class 1W and 1G, respectively) and to the cumulative volume ofproduced gas (up to 45 percent and 54 percent in Class 1W and 1G,respectively). Large volumes of <span class="hlt">hydrate</span>-originating CH4 could be producedfrom Class 2 <span class="hlt">hydrates</span>, but a relatively long lead <span class="hlt">time</span> would be neededbefore gas production (which continuously increases over <span class="hlt">time</span>) attains asubstantial level. The permeability of the confining boundaries plays asignificant role in gas production from Class 2 deposits. In general,long-term production is needed to realize the full potential of the verypromising Class 1 and Class 2 <span class="hlt">hydrate</span> deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25075330','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25075330"><span>Acemetacin cocrystals and salts: structure solution from <span class="hlt">powder</span> X-ray data and form selection of the piperazine salt.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir</p> <p>2014-03-01</p> <p>Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble <span class="hlt">hydrate</span> in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a <span class="hlt">hydrate</span> during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid <span class="hlt">hydration</span>. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM-INA cocrystal and a binary adduct ACM-PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM-PAM and ACM-CPR, and the piperazine salt ACM-PPZ were solved from high-resolution <span class="hlt">powder</span> X-ray diffraction data. The ACM-INA cocrystal is sustained by the acid⋯pyridine heterosynthon and N-H⋯O catemer hydrogen bonds involving the amide group. The acid⋯amide heterosynthon is present in the ACM-PAM cocrystal, while ACM-CPR contains carboxamide dimers of caprolactam along with acid-carbonyl (ACM) hydrogen bonds. The cocrystals ACM-INA, ACM-PAM and ACM-CPR are three-dimensional isostructural. The carboxyl⋯carboxyl synthon in ACM-PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM <span class="hlt">hydrate</span> during the same <span class="hlt">time</span> period. The ACM-PPZ salt and ACM-nicotinamide cocrystal dissolve five <span class="hlt">times</span> faster than the stable <span class="hlt">hydrate</span> form, whereas the ACM-PABA adduct has 2.5 <span class="hlt">times</span> faster dissolution rate. The pharmaceutically acceptable piperazine salt of acemetacin exhibits superior</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4062091','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4062091"><span>Acemetacin cocrystals and salts: structure solution from <span class="hlt">powder</span> X-ray data and form selection of the piperazine salt</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir</p> <p>2014-01-01</p> <p>Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble <span class="hlt">hydrate</span> in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a <span class="hlt">hydrate</span> during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid <span class="hlt">hydration</span>. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution <span class="hlt">powder</span> X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid⋯pyridine heterosynthon and N—H⋯O catemer hydrogen bonds involving the amide group. The acid⋯amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl⋯carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM <span class="hlt">hydrate</span> during the same <span class="hlt">time</span> period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five <span class="hlt">times</span> faster than the stable <span class="hlt">hydrate</span> form, whereas the ACM–PABA adduct has 2.5 <span class="hlt">times</span> faster dissolution rate. The pharmaceutically acceptable piperazine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26636354','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26636354"><span>Determination of Protein Surface <span class="hlt">Hydration</span> by Systematic Charge Mutations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jia, Menghui; Yang, Jin; Qin, Yangzhong; Wang, Dihao; Pan, Haifeng; Wang, Lijuan; Xu, Jianhua; Zhong, Dongping</p> <p>2015-12-17</p> <p>Protein surface <span class="hlt">hydration</span> is critical to its structural stability, flexibility, dynamics, and function. Recent observations of surface solvation on picosecond <span class="hlt">time</span> scales have evoked debate on the origin of such relatively slow motions, from <span class="hlt">hydration</span> water or protein charged side chains, especially with molecular dynamics simulations. Here we used a unique nuclease with a single tryptophan as a local probe and systematically mutated three neighboring charged residues to differentiate the contributions from <span class="hlt">hydration</span> water and charged side chains. By various mutations of one, two, and all three charged residues, we observed slight increases in the total tryptophan Stokes shifts with fewer neighboring charged residue(s) and found insensitivity of charged side chains to the relaxation patterns. The dynamics is correlated with <span class="hlt">hydration</span> water relaxation with the slowest <span class="hlt">time</span> in a dense charged environment and the fastest <span class="hlt">time</span> at a hydrophobic site. On such picosecond <span class="hlt">time</span> scales, the protein surface motion is restricted. The total Stokes shifts are dominantly from <span class="hlt">hydration</span> water relaxation and the slow dynamics is from water-driven relaxation, coupled to local protein fluctuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JChPh.139l1102S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JChPh.139l1102S"><span>Communication: Protein dynamical transition vs. liquid-liquid phase transition in protein <span class="hlt">hydration</span> water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schirò, Giorgio; Fomina, Margarita; Cupane, Antonio</p> <p>2013-09-01</p> <p>In this work, we compare experimental data on myoglobin <span class="hlt">hydrated</span> <span class="hlt">powders</span> from elastic neutron scattering, broadband dielectric spectroscopy, and differential scanning calorimetry. Our aim is to obtain new insights on the connection between the protein dynamical transition, a fundamental phenomenon observed in proteins whose physical origin is highly debated, and the liquid-liquid phase transition (LLPT) possibly occurring in protein <span class="hlt">hydration</span> water and related to the existence of a low temperature critical point in supercooled water. Our results provide a consistent thermodynamic/dynamic description which gives experimental support to the LLPT hypothesis and further reveals how fundamental properties of water and proteins are tightly related.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21766150','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21766150"><span>High hatching rates after cryopreservation of <span class="hlt">hydrated</span> cysts of the brine shrimp A. franciscana.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yoshida, Toru; Arii, Yasuhiro; Hino, Katsuhiko; Sawatani, Ikuo; Tanaka, Midori; Takahashi, Rei; Bando, Toru; Mukai, Kazuhisa; Fukuo, Keisuke</p> <p>2011-01-01</p> <p>Cysts of Artemia franciscana are known to be extremely tolerant to UV and ionizing radiation, hypoxia, dryness, osmotic pressure, and temperatures. However, when cysts are <span class="hlt">hydrated</span>, their resistance to extreme environmental conditions is markedly reduced, and they subsequently enter a developmental sequence. The hatching rate of <span class="hlt">hydrated</span> cysts declined when they were rapidly frozen after a short period of <span class="hlt">hydration</span> but slow freezing improved hatching rates after 6-h <span class="hlt">hydration</span> (1.4 g H2O per g dry wt). We observed that trehalose content in <span class="hlt">hydrated</span> cysts was greatly reduced up to 6-h <span class="hlt">time</span>. DSC analysis showed different thermal profiles at two cooling rates, suggesting the formation of a minuscule ice crystal inside the cells. High hatching rates can be obtained from highly <span class="hlt">hydrated</span> cysts at slow cooling rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007EPJST.141..223Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007EPJST.141..223Y"><span><span class="hlt">Hydration</span> water in dynamics of a <span class="hlt">hydrated</span> beta-lactoglobulin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.-C.; Longeville, S.</p> <p>2007-02-01</p> <p>Incoherent spin-echo signals of a <span class="hlt">hydrated</span> β-lactoglobulin protein were investigated, at 275 and 293 K. The intermediate scattering functions I(Q,t) were divided in two contributions from surface water and protein, respectively. On one hand, the dynamics of the surface water follows a KWW stretched exponential function (the exponent is ~0.5), on the other hand, that of the protein follows a single exponential. The present results are consistent with our previous results of <span class="hlt">hydrated</span> C-phycocyanin combining elastic and quasielastic neutron scattering and by molecular dynamics simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CPL...683..658Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CPL...683..658Q"><span>Dynamics of <span class="hlt">hydration</span> water and coupled protein sidechains around a polymerase protein surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Yangzhong; Yang, Yi; Wang, Lijuan; Zhong, Dongping</p> <p>2017-09-01</p> <p>Water-protein coupled interactions are essential to the protein structural stability, flexibility and dynamic functions. The ultimate effects of the <span class="hlt">hydration</span> dynamics on the protein fluctuations remain substantially unexplored. Here, we investigated the dynamics of both <span class="hlt">hydration</span> water and protein sidechains at 13 different sites around the polymerase β protein surface using a tryptophan scan with femtosecond spectroscopy. Three types of <span class="hlt">hydration</span>-water relaxations and two types of protein sidechain motions were determined, reflecting a highly dynamic water-protein interactions fluctuating on the picosecond <span class="hlt">time</span> scales. The <span class="hlt">hydration</span>-water dynamics dominate the coupled interactions with higher flexibility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.agu.org/pubs/crossref/2010/2009JB006670.shtml','USGSPUBS'); return false;" href="http://www.agu.org/pubs/crossref/2010/2009JB006670.shtml"><span>Parametric study of the physical properties of <span class="hlt">hydrate</span>-bearing sand, silt, and clay sediments: 2. Small-strain mechanical properties</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, J.Y.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.</p> <p>2010-01-01</p> <p>The small-strain mechanical properties (e.g., seismic velocities) of <span class="hlt">hydrate</span>-bearing sediments measured under laboratory conditions provide reference values for calibration of logging and seismic exploration results acquired in <span class="hlt">hydrate</span>-bearing formations. Instrumented cells were designed for measuring the compressional (P) and shear (S) velocities of sand, silts, and clay with and without <span class="hlt">hydrate</span> and subject to vertical effective stresses of 0.01 to 2 MPa. Tetrahydrofuran (THF), which is fully miscible in water, was used as the <span class="hlt">hydrate</span> former to permit close control over the <span class="hlt">hydrate</span> saturation Shyd and to produce <span class="hlt">hydrate</span> from dissolved phase, as methane <span class="hlt">hydrate</span> forms in most natural marine settings. The results demonstrate that laboratory <span class="hlt">hydrate</span> formation technique controls the pattern of P and S velocity changes with increasing Shyd and that the small-strain properties of <span class="hlt">hydrate</span>-bearing sediments are governed by effective stress, δ'v and sediment specific surface. The S velocity increases with <span class="hlt">hydrate</span> saturation owing to an increase in skeletal shear stiffness, particularly when <span class="hlt">hydrate</span> saturation exceeds Shyd≈ 0.4. At very high <span class="hlt">hydrate</span> saturations, the small strain shear stiffness is determined by the presence of <span class="hlt">hydrates</span> and becomes insensitive to changes in effective stress. The P velocity increases with <span class="hlt">hydrate</span> saturation due to the increases in both the shear modulus of the skeleton and the bulk modulus of pore-filling phases during fluid-to-<span class="hlt">hydrate</span> conversion. Small-strain Poisson's ratio varies from 0.5 in soft sediments lacking <span class="hlt">hydrates</span> to 0.25 in stiff sediments (i.e., subject to high vertical effective stress or having high Shyd). At Shyd ≥ 0.5, <span class="hlt">hydrate</span> hinders expansion and the loss of sediment stiffness during reduction of vertical effective stress, meaning that <span class="hlt">hydrate</span>-rich natural sediments obtained through pressure coring should retain their in situ fabric for some <span class="hlt">time</span> after core retrieval if the cores are maintained within the <span class="hlt">hydrate</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRB..11511105L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRB..11511105L"><span>Parametric study of the physical properties of <span class="hlt">hydrate</span>-bearing sand, silt, and clay sediments: 2. Small-strain mechanical properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, J. Y.; Francisca, F. M.; Santamarina, J. C.; Ruppel, C.</p> <p>2010-11-01</p> <p>The small-strain mechanical properties (e.g., seismic velocities) of <span class="hlt">hydrate</span>-bearing sediments measured under laboratory conditions provide reference values for calibration of logging and seismic exploration results acquired in <span class="hlt">hydrate</span>-bearing formations. Instrumented cells were designed for measuring the compressional (P) and shear (S) velocities of sand, silts, and clay with and without <span class="hlt">hydrate</span> and subject to vertical effective stresses of 0.01 to 2 MPa. Tetrahydrofuran (THF), which is fully miscible in water, was used as the <span class="hlt">hydrate</span> former to permit close control over the <span class="hlt">hydrate</span> saturation Shyd and to produce <span class="hlt">hydrate</span> from dissolved phase, as methane <span class="hlt">hydrate</span> forms in most natural marine settings. The results demonstrate that laboratory <span class="hlt">hydrate</span> formation technique controls the pattern of P and S velocity changes with increasing Shyd and that the small-strain properties of <span class="hlt">hydrate</span>-bearing sediments are governed by effective stress, σ'v and sediment specific surface. The S velocity increases with <span class="hlt">hydrate</span> saturation owing to an increase in skeletal shear stiffness, particularly when <span class="hlt">hydrate</span> saturation exceeds Shyd≈ 0.4. At very high <span class="hlt">hydrate</span> saturations, the small strain shear stiffness is determined by the presence of <span class="hlt">hydrates</span> and becomes insensitive to changes in effective stress. The P velocity increases with <span class="hlt">hydrate</span> saturation due to the increases in both the shear modulus of the skeleton and the bulk modulus of pore-filling phases during fluid-to-<span class="hlt">hydrate</span> conversion. Small-strain Poisson's ratio varies from 0.5 in soft sediments lacking <span class="hlt">hydrates</span> to 0.25 in stiff sediments (i.e., subject to high vertical effective stress or having high Shyd). At Shyd ≥ 0.5, <span class="hlt">hydrate</span> hinders expansion and the loss of sediment stiffness during reduction of vertical effective stress, meaning that <span class="hlt">hydrate</span>-rich natural sediments obtained through pressure coring should retain their in situ fabric for some <span class="hlt">time</span> after core retrieval if the cores are maintained within the <span class="hlt">hydrate</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22624890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22624890"><span>Comparison of stromal <span class="hlt">hydration</span> techniques for clear corneal cataract incisions: conventional <span class="hlt">hydration</span> versus anterior stromal pocket <span class="hlt">hydration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mifflin, Mark D; Kinard, Krista; Neuffer, Marcus C</p> <p>2012-06-01</p> <p>Anterior stromal pocket <span class="hlt">hydration</span> was compared with conventional <span class="hlt">hydration</span> for preventing wound leak after 2.8 mm uniplanar clear corneal incisions (CCIs) in patients having routine cataract surgery. Conventional <span class="hlt">hydration</span> involves <span class="hlt">hydration</span> of the lateral walls of the main incision with visible whitening of the stroma. The anterior stromal pocket <span class="hlt">hydration</span> technique involves creation of an additional supraincisional stromal pocket overlying the main incision, which is then <span class="hlt">hydrated</span> instead of the main incision. Sixty-six eyes of 48 patients were included in the data analysis with 33 assigned to each study group. The anterior stromal pocket <span class="hlt">hydration</span> technique was significantly better than conventional <span class="hlt">hydration</span> in preventing wound leak due to direct pressure on the posterior lip of the incision. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026850','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026850"><span>The effect of elevated methane pressure on methane <span class="hlt">hydrate</span> dissociation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Circone, S.; Stern, L.A.; Kirby, S.H.</p> <p>2004-01-01</p> <p>Methane <span class="hlt">hydrate</span>, equilibrated at P, T conditions within the <span class="hlt">hydrate</span> stability field, was rapidly depressurized to 1.0 or 2.0 MPa and maintained at isobaric conditions outside its stability field, while the extent and rate of <span class="hlt">hydrate</span> dissociation was measured at fixed, externally maintained temperatures between 250 and 288 K. The dissociation rate decreases with increasing pressure at a given temperature. Dissociation rates at 1.0 MPa parallel the complex, reproducible T-dependence previously observed between 250 and 272 K at 0.1 MPa. The lowest rates were observed near 268 K, such that >50% of the sample can persist for more than two weeks at 0.1 MPa to more than a month at 1 and 2 MPa. Varying the pressure stepwise in a single experiment increased or decreased the dissociation rate in proportion to the rates observed in the isobaric experiments, similar to the rate reversibility previously observed with stepwise changes in temperature at 0.1 MPa. At fixed P, T conditions, the rate of methane <span class="hlt">hydrate</span> dissociation decreases monotonically with <span class="hlt">time</span>, never achieving a steady rate. The relationship between <span class="hlt">time</span> (t) and the extent of <span class="hlt">hydrate</span> dissociation is empirically described by: Evolved gas (%) = A??tB where the pre-exponential term A ranges from 0 to 16% s-B and the exponent B is generally <1. Based on fits of the dissociation results to Equation 1 for the full range of temperatures (204 to 289 K) and pressures (0.1 to 2.0 MPa) investigated, the derived parameters can be used to predict the methane evolution curves for pure, porous methane <span class="hlt">hydrate</span> to within ??5%. The effects of sample porosity and the presence of quartz sand and seawater on methane <span class="hlt">hydrate</span> dissociation are also described using Equation 1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19303131','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19303131"><span>Controversies about the occurrence of chloral <span class="hlt">hydrate</span> in drinking water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dabrowska, Agata; Nawrocki, Jacek</p> <p>2009-05-01</p> <p>Besides trihalomethanes (THMs) and haloacetic acids (HAAs), chloral <span class="hlt">hydrate</span> (CH) is the next most prevalent disinfection by-product (DBP) in drinking water, formed as a result of the reaction between chlorine and natural organic matter (NOM). Chloral <span class="hlt">hydrate</span> (trichloroacetaldehyde) should be limited in drinking water because of its adverse health effect. The controversies concerning the appearance of CH in disinfected water found in literature are discussed in the present paper. According to some authors the CH yield during chlorination of water depends only on TOC. However, there are other data available that do not confirm this relationship. Another fact requiring clarification is the dependence of CH formation on pH. In the present study, CH formation is analysed in different types of water disinfected with different doses of chlorine. Formation of CH is correlated with the dose of Cl(2) and the contact <span class="hlt">time</span>. The formation of chloral <span class="hlt">hydrate</span> takes place as long as chlorine is available in the water. Total organic carbon (TOC) is not considered the main factor influencing the production of chloral <span class="hlt">hydrate</span> in water treated with Cl(2) as the production depends also on the nature of NOM. Higher levels of CH are observed at alkaline conditions (pH>7). A significant correlation (R(2)>0.9) between the concentrations of chloral <span class="hlt">hydrate</span> and chloroform has been observed. The preozonation increases significantly the chloral <span class="hlt">hydrate</span> formation potential in the water treated. Biofiltration process does not remove all of CH precursors and its efficiency depends strongly on the contact <span class="hlt">time</span>. Chloral <span class="hlt">hydrate</span> was analyzed by gas chromatography with electron capture detector with the detection limit 0.1 microg L(-1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS43B1815E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS43B1815E"><span>CO2 + N2O mixture gas <span class="hlt">hydrate</span> formation kinetics and effect of soil minerals on mixture-gas <span class="hlt">hydrate</span> formation process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Enkh-Amgalan, T.; Kyung, D.; Lee, W.</p> <p>2012-12-01</p> <p>CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) <span class="hlt">hydrate</span> formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make <span class="hlt">hydrate</span> to mitigate N20 and CO2 in same <span class="hlt">time</span>. Mixture gas <span class="hlt">hydrate</span> formation periods were approximately two <span class="hlt">times</span> faster than pure N2O <span class="hlt">hydrate</span> formation kinetic in general. The fastest induction <span class="hlt">time</span> of mixture-gas <span class="hlt">hydrate</span> formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that <span class="hlt">hydrate</span> formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on <span class="hlt">hydrate</span> formation kinetic; however, induction <span class="hlt">time</span> can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of <span class="hlt">hydrate</span> formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas <span class="hlt">hydrates</span>. We have also performed molecular dynamics computer simulations on N2O and CO2 <span class="hlt">hydrate</span> structures to estimate the residual free energy of two-phase (<span class="hlt">hydrate</span> cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O <span class="hlt">hydrates</span> are thermodynamically stable at real-world gas <span class="hlt">hydrate</span> existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6824342','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6824342"><span>Well log evaluation of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.</p> <p>1992-10-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas <span class="hlt">hydrates</span> are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane <span class="hlt">hydrates</span> appear to be the most common in nature. The amount of methane sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the <span class="hlt">hydrate</span> reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas <span class="hlt">hydrates</span> also represent a significant drilling and production hazard. A fundamental question linking gas <span class="hlt">hydrate</span> resource and hazard issues is: What is the volume of gas <span class="hlt">hydrates</span> and included gas within a given gas <span class="hlt">hydrate</span> occurrence Most published gas <span class="hlt">hydrate</span> resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas <span class="hlt">hydrates</span> are dependent on a number of reservoir parameters, including the areal extent ofthe gas-<span class="hlt">hydrate</span> occurrence, reservoir thickness, <span class="hlt">hydrate</span> number, reservoir porosity, and the degree of gas-<span class="hlt">hydrate</span> saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas <span class="hlt">hydrate</span> saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-<span class="hlt">hydrate</span>-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10142315','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10142315"><span>Well log evaluation of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.</p> <p>1992-10-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas <span class="hlt">hydrates</span> are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane <span class="hlt">hydrates</span> appear to be the most common in nature. The amount of methane sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the <span class="hlt">hydrate</span> reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas <span class="hlt">hydrates</span> also represent a significant drilling and production hazard. A fundamental question linking gas <span class="hlt">hydrate</span> resource and hazard issues is: What is the volume of gas <span class="hlt">hydrates</span> and included gas within a given gas <span class="hlt">hydrate</span> occurrence? Most published gas <span class="hlt">hydrate</span> resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas <span class="hlt">hydrates</span> are dependent on a number of reservoir parameters, including the areal extent ofthe gas-<span class="hlt">hydrate</span> occurrence, reservoir thickness, <span class="hlt">hydrate</span> number, reservoir porosity, and the degree of gas-<span class="hlt">hydrate</span> saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas <span class="hlt">hydrate</span> saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-<span class="hlt">hydrate</span>-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1299483','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1299483"><span><span class="hlt">Hydration</span> of polyethylene glycol-grafted liposomes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tirosh, O; Barenholz, Y; Katzhendler, J; Priev, A</p> <p>1998-01-01</p> <p>This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the <span class="hlt">hydration</span> and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and <span class="hlt">hydrational</span> characterization. Using a differential scanning calorimetry techn