WorldWideScience

Sample records for fully hydrated ripple-phase

  1. Molecular structure of the lecithin ripple phase

    Science.gov (United States)

    de Vries, Alex H.; Yefimov, Serge; Mark, Alan E.; Marrink, Siewert J.

    2005-04-01

    Molecular dynamics simulations of lecithin lipid bilayers in water as they are cooled from the liquid crystalline phase show the spontaneous formation of rippled bilayers. The ripple consists of two domains of different length and orientation, connected by a kink. The organization of the lipids in one domain of the ripple is found to be that of a splayed gel; in the other domain the lipids are gel-like and fully interdigitated. In the concave part of the kink region between the domains the lipids are disordered. The results are consistent with the experimental information available and provide an atomic-level model that may be tested by further experiments. molecular dynamics simulation | structural model

  2. Correlation between the ripple phase and stripe domains in membranes.

    Science.gov (United States)

    Bernchou, Uffe; Midtiby, Henrik; Ipsen, John Hjort; Simonsen, Adam Cohen

    2011-12-01

    We investigate the relationship between stripe domains and the ripple phase in membranes. These have previously been observed separately without being linked explicitly. Past results have demonstrated that solid and ripple phases exhibit rich textural patterns related to the orientational order of tilted lipids and the orientation of ripple corrugations. Here we reveal a highly complex network pattern of ripple and solid domains in DLPC, DPPC bilayers with structures covering length scales from 10 nm to 100 μm. Using spincoated double supported membranes we investigate domains by correlated AFM and fluorescence microscopy. Cooling experiments demonstrate the mode of nucleation and growth of stripe domains enriched in the fluorescent probe. Concurrent AFM imaging reveals that these stripe domains have a one-to-one correspondence with a rippled morphology running parallel to the stripe direction. Both thin and thick stripe domains are observed having ripple periods of 13.5±0.2 nm and 27.4±0.6 nm respectively. These are equivalent to previously observed asymmetric/equilibrium and symmetric/metastable ripple phases, respectively. Thin stripes grow from small solid domains and grow predominantly in length with a speed of ~3 times that of the thick stripes. Thick stripes grow by templating on the sides of thinner stripes or can emerge directly from the fluid phase. Bending and branching angles of stripes are in accordance with an underlying six fold lattice. We discuss mechanisms for the nucleation and growth of ripples and discuss a generic phase diagram that may partly rationalize the coexistence of metastable and stable phases. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Structure of the ripple phase of phospholipid multibilayers

    International Nuclear Information System (INIS)

    Sengupta, Kheya; Raghunathan, V.A.; Katsaras, John

    2003-01-01

    We present electron density maps (EDMs) of the ripple phase formed by phosphorylcholine lipids such as dimyristoyl phosphatidylcholine (DMPC), palmitoyl-oleoyl phosphatidylcholine (POPC), dihexadecyl phosphatidylcholine, and dilauroyl phosphatidylcholine (DLPC). With the exception of DLPC, the rippled bilayers have a sawtooth shape in all the systems, with one arm being almost twice as long as the other. For DMPC and POPC bilayers, EDMs have been obtained at different temperatures at a fixed relative humidity, and the overall shape of the ripples and the ratio of the lengths of the two arms are found to be insensitive to temperature. EDMs of all the systems with saturated hydrocarbon chains suggest the existence of a mean chain tilt along the ripple wave vector. In the literature it is generally assumed that the asymmetry of the rippled bilayers (absence of a mirror plane normal to the ripple wave vector) arises from a sawtoothlike height profile. However, in the case of DLPC, the height profile is found to be almost symmetric and the asymmetry results mainly from different bilayer thicknesses in the two arms of the ripple. We also present EDMs of the metastable ripple phase of dipalmitoyl phosphatidylcholine, formed on cooling from the L α phase

  4. Temperature-Controlled High-Speed AFM: Real-Time Observation of Ripple Phase Transitions.

    Science.gov (United States)

    Takahashi, Hirohide; Miyagi, Atsushi; Redondo-Morata, Lorena; Scheuring, Simon

    2016-11-01

    With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity. Because of its narrow regime of existence and heterogeneity ripple phase and its transition dynamics remain poorly understood. Here, a temperature control device to high-speed atomic force microscopy (HS-AFM) to observe dynamics of phase transition from ripple phase to fluid phase reversibly in real time is developed and integrated. Based on HS-AFM imaging, the phase transition processes from ripple phase to fluid phase and from ripple phase to metastable ripple phase to fluid phase could be reversibly, phenomenologically, and quantitatively studied. The results here show phase transition hysteresis in fast cooling and heating processes, while both melting and condensation occur at 24.15 °C in quasi-steady state situation. A second metastable ripple phase with larger periodicity is formed at the ripple phase to fluid phase transition when the buffer contains Ca 2+ . The presented temperature-controlled HS-AFM is a new unique experimental system to observe dynamics of temperature-sensitive processes at the nanoscopic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Molecular dynamics simulations of a fully hydrated dipalmitoyl phosphatidylcholine bilayer with different macroscopic boundary conditions and parameters

    NARCIS (Netherlands)

    Tieleman, D.P; Berendsen, H.J.C.

    1996-01-01

    We compared molecular dynamics simulations of a bilayer of 128 fully hydrated phospholipid (DPPC) molecules, using different parameters and macroscopic boundary conditions. The same system was studied under constant pressure, constant volume, and constant surface tension boundary conditions, with

  6. Electrochemical impedance spectroscopy of fully hydrated Nafion membranes at high and low hydrogen partial pressures

    International Nuclear Information System (INIS)

    Tsampas, M.N.; Brosda, S.; Vayenas, C.G.

    2011-01-01

    The proton transport mechanism in fully hydrated Nafion 117 membranes was examined via electrochemical impedance spectroscopy (EIS) and steady-state current–potential measurements both in a symmetric H 2 , Pt|Nafion|Pt, H 2 cell and in a H 2 , Pt|Nafion|Pt, air PEM fuel cell with hydrogen partial pressure values, P H 2 , varied between 0.5 kPa and 100 kPa. In agreement with recent studies it is found that for low P H 2 values the steady-state current–potential curves exhibit bistability and regions of positive slope. In these regions the Nyquist plots are found to exhibit negative real part impedance with a large imaginary component, while the Bode plots show a pronounced negative phase shift. These observations are consistent with the mechanism involving two parallel routes of proton conduction in fully hydrated Nafion membranes, one due to proton migration in the aqueous phase, the other due to proton transfer, probably involving tunneling, between adjacent sulfonate groups in narrow pores. The former mechanism dominates at high P H 2 values and the latter dominates in the low P H 2 region where the real part of the impedance is negative.

  7. Temperature-controlled structure and kinetics of ripple phases in one- and two-component supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Crowe, J.H.

    2003-01-01

    Temperature-controlled atomic force microscopy (AFM) has been used to visualize and study the structure and kinetics of ripple phases in one-component dipalmitoylphosphaticlylcholine (DPPC) and two-component dimyristoylphosphatidylcholine-distearoylphosphatidylcholine (DMPC-DSPC) lipid bilayers....... The lipid bilayers are mica-supported double bilayers in which ripple-phase formation occurs in the top bilayer. In one-component DPPC lipid bilayers, the stable and metastable ripple phases were observed. In addition, a third ripple structure with approximately twice the wavelength of the metastable...... ripples was seen. From height profiles of the AFM images, estimates of the amplitudes of the different ripple phases are reported. To elucidate the processes of ripple formation and disappearance, a ripple-phase DPPC lipid bilayer was taken through the pretransition in the cooling and the heating...

  8. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes

    International Nuclear Information System (INIS)

    Yang, J.; Martí, J.; Calero, C.

    2014-01-01

    Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10 −5 cm 2 /s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10 −8 cm 2 /s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2–8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of its interaction

  9. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.; Martí, J., E-mail: jordi.marti@upc.edu [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Calero, C. [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Center for Polymer Studies, Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States)

    2014-03-14

    Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10{sup −5} cm{sup 2}/s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10{sup −8} cm{sup 2}/s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2–8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of

  10. Small-angle scattering studies of the fully hydrated phospholipid DPPC

    Energy Technology Data Exchange (ETDEWEB)

    Mason, P.C.; Gaulin, B.D. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (CANADA); Epand, R.M. [Department of Biochemistry, McMaster University, Hamilton, Ontario, L8N 3Z5 (CANADA); Wignall, G.D.; Lin, J.S. [Center for Small-Angle Scattering Research, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    1999-01-01

    Small-angle neutron and x-ray scattering studies have been carried out on fully hydrated dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles. This system is known to exhibit two distinct ripple (P{sub {beta}{sup {prime}}}) phases, which depend on sample history, at temperatures intermediate to its high-temperature liquid crystalline (L{sub {alpha}}), phase, and its low-temperature gel (L{sub {beta}{sup {prime}}}), phase. On cooling from the L{sub {alpha}} phase, the P{sub {beta}{sup {prime}}} phase displays a complex multipeak diffraction pattern that differs significantly from the diffraction pattern seen in the P{sub {beta}{sup {prime}}} phase obtained on warming from the L{sub {beta}{sup {prime}}} phase. Examining the P{sub {beta}{sup {prime}}} phase on cooling using small-angle neutron scattering and x-ray diffraction techniques leads to the conclusion that this phase is characterized by a long wavelength ripple ({lambda}{sub r}{approximately}330thinsp{Angstrom}) and a highly monoclinic unit cell ({gamma}{approximately}125{degree}). As the P{sub {beta}{sup {prime}}} phase is traversed in temperature, the ripple wavelength changes significantly while the monoclinicity remains unchanged. Ripples from the P{sub {beta}{sup {prime}}} phase are seen to persist into the L{sub {beta}{sup {prime}}} phase on cooling, leading to increased small-angle scattering characteristic of a disordered stacking of the lamellae. {copyright} {ital 1999} {ital The American Physical Society}

  11. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    , not all of them are white like snow. Some hydrates from the deep Gulf of Mexico are richly colored in shades of yellow, orange, or even red. The ice-like masses are beautiful, and contrast with the dull gray of deep sea muds. Hydrates from the Blake... volcanoes and associated gas hydrates: Marine Geology, v. 167, p. 29-42. Milkov, A.V. and R. Sassen, 2001a, Estimate of gas hydrate resource, northwestern Gulf of Mexico continental slope: Marine Geology, v. 179, pp. 71-83. Milkov, A.V., Sassen, R...

  12. Historical methane hydrate project review

    Science.gov (United States)

    Collett, Timothy; Bahk, Jang-Jun; Frye, Matt; Goldberg, Dave; Husebo, Jarle; Koh, Carolyn; Malone, Mitch; Shipp, Craig; Torres, Marta

    2013-01-01

    which have been effectively used to collect invaluable geologic and engineering data on the occurrence of methane hydrates throughout the world. Technologies designed specifically for the collection and analysis of undisturbed methane hydrate samples have included the development of a host of pressure core systems and associated specialty laboratory apparatus. The study and use of both wireline conveyed and logging-­‐while-­‐drilling technologies have also contributed greatly to our understanding of the in-­‐situ nature of hydrate-­‐bearing sediments. Recent developments in borehole instrumentation specifically designed to monitor changes associated with hydrates in nature through time or to evaluate the response of hydrate accumulations to production have also contributed greatly to our understanding of the complex nature and evolution of methane hydrate systems.Our understanding of how methane hydrates occur and behave in nature is still growing and evolving – we do not yet know if methane hydrates can be economically produced, nor do we know fully the role of hydrates as an agent of climate change or as a geologic hazard. But it is known for certain that scientific drilling has contributed greatly to our understanding of hydrates in nature and will continue to be a critical source of the information to advance our understanding of methane hydrates.

  13. Chloral Hydrate

    Science.gov (United States)

    ... if you are allergic to chloral hydrate, aspirin, tartrazine (a yellow dye in some processed foods and ... in, tightly closed, and out of reach of children. Store it at room temperature, away from excess ...

  14. [Skin hydration and hydrating products].

    Science.gov (United States)

    Duplan, H; Nocera, T

    2018-05-01

    One of the skin's principal functions is to protect the body against its environment by maintaining an effective epidermal barrier, not only against external factors, but also to prevent water loss from the body. Indeed, water homeostasis is vital for the normal physiological functioning of skin. Hydration levels affect not only visible microscopic parameters such as the suppleness and softness of skin, but also molecular parameters, enzyme activities and cellular signalling within the epidermis. The body is continually losing some of its water, but this phenomenon is limited and the optimal hydration gradient in skin is ensured via a set of sophisticated regulatory processes that rely on the functional and dynamic properties of the uppermost level of the skin consisting of the stratum corneum. The present article brings together data recently acquired in the fields of skin hydration and the characterisation of dehydrated or dry skin, whether through study of the regulatory processes involved or as a result of changes in the techniques used for in situ measurement, and thus in optimisation of management. Copyright © 2018. Published by Elsevier Masson SAS.

  15. Molecular structure of the lecithin ripple phase

    NARCIS (Netherlands)

    de Vries, AH; Yefimov, S; Mark, AE; Marrink, SJ

    2005-01-01

    Molecular dynamics simulations of lecithin lipid bilayers in water as they are cooled from the liquid crystalline phase show the spontaneous formation of rippled bilayers. The ripple consists of two domains of different length and orientation, connected by a kink. The organization of the lipids in

  16. Geologic implications of gas hydrates in the offshore of India: results of the National Gas Hydrate Program Expedition 01

    Science.gov (United States)

    Collett, Timothy S.; Boswell, Ray; Cochran, J.R.; Kumar, Pushpendra; Lall, Malcolm; Mazumdar, Aninda; Ramana, Mangipudi Venkata; Ramprasad, Tammisetti; Riedel, Michael; Sain, Kalachand; Sathe, Arun Vasant; Vishwanath, Krishna

    2014-01-01

    The Indian National Gas Hydrate Program Expedition 01 (NGHP-01) is designed to study the occurrence of gas hydrate along the passive continental margin of the Indian Peninsula and in the Andaman convergent margin, with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. The NGHP-01 expedition established the presence of gas hydrates in the Krishna-Godavari and Mahanadi Basins, and the Andaman Sea. The expedition discovered in the Krishna-Godavari Basin one of the thickest gas hydrate accumulations ever documented, in the Andaman Sea one of the thickest and deepest gas hydrate stability zones in the world, and established the existence of a fully developed gas hydrate petroleum system in all three basins.

  17. Artificial Hydration and Nutrition

    Science.gov (United States)

    ... Crisis Situations Pets and Animals myhealthfinder Food and Nutrition Healthy Food Choices Weight Loss and Diet Plans ... Your Health Resources Healthcare Management Artificial Hydration and Nutrition Artificial Hydration and Nutrition Share Print Patients who ...

  18. Detection and Production of Methane Hydrate

    Energy Technology Data Exchange (ETDEWEB)

    George Hirasaki; Walter Chapman; Gerald Dickens; Colin Zelt; Brandon Dugan; Kishore Mohanty; Priyank Jaiswal

    2011-12-31

    This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand

  19. Gas hydrate in nature

    Science.gov (United States)

    Ruppel, Carolyn D.

    2018-01-17

    Gas hydrate is a naturally occurring, ice-like substance that forms when water and gas combine under high pressure and at moderate temperatures. Methane is the most common gas present in gas hydrate, although other gases may also be included in hydrate structures, particularly in areas close to conventional oil and gas reservoirs. Gas hydrate is widespread in ocean-bottom sediments at water depths greater than 300–500 meters (m; 984–1,640 feet [ft]) and is also present in areas with permanently frozen ground (permafrost). Several countries are evaluating gas hydrate as a possible energy resource in deepwater or permafrost settings. Gas hydrate is also under investigation to determine how environmental change may affect these deposits.

  20. Gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

  1. Gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

  2. Indian continental margin gas hydrate prospects : results of the Indian National Gas Hydrate Program (NGHP) expedition 01

    Energy Technology Data Exchange (ETDEWEB)

    Collett, T [United States Geological Survey, Denver, CO (United States); Riedel, M. [McGill Univ., Montreal, PQ (Canada). Dept. of Earth and Planetary Sciences; Cochran, J.R. [Columbia Univ., Palisades, NY (United States). Lamont Doherty Earth Observatory; Boswell, R. [United States Dept. of Energy, Morgantown, WV (United States). National Energy Technology Lab; Kumar, P. [Pushpendra Kumar Oil and Natural Gas Corp. Ltd., Mumbai (India). Inst. of Engineering and Ocean Technology; Sathe, A.V. [Oil and Natural Gas Corp. Ltd., Uttaranchal (India). KDM Inst. of Petroleum Exploration

    2008-07-01

    The geologic occurrence of gas hydrate deposits along the continental margins of India were investigated in the first expedition of the Indian National Gas Hydrate Program (NGHP). The objective was to determine the regional context and characteristics of the gas hydrate deposits through scientific ocean drilling, logging, and analytical activities. A research drill ship was the platform for the drilling operation. The geological and geophysical studies revealed 2 geologically distinct areas with inferred gas hydrate occurrences, notably the passive continental margins of the Indian Peninsula and along the Andaman convergent margin. The NGHP Expedition 01 focused on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these 2 diverse settings. The study established the presence of gas hydrates in Krishna-Godavari, Mahanadi and Andaman basins. Site 10 in the Krishna-Godavari Basin was discovered to be the one of the richest gas hydrate accumulations yet documented, while site 17 in the Andaman Sea had the thickest and deepest gas hydrate stability zone yet known. The existence of a fully-developed gas hydrate system in the Mahanadi Basin was also discovered. Most of the gas hydrate occurrences discovered during this expedition appeared to contain mostly methane which was generated by microbial processes. However, there was also evidence of a thermal origin for a portion of the gas within the hydrates of the Mahanadi Basin and the Andaman offshore area. Gas hydrate in the Krishna-Godavari Basin appeared to be closely associated with large scale structural features, in which the flux of gas through local fracture systems, generated by the regional stress regime, controlled the occurrence of gas hydrate. 3 refs., 1 tab., 2 figs.

  3. Hydrated Electron Transfer to Nucleobases in Aqueous Solutions Revealed by Ab Initio Molecular Dynamics Simulations.

    Science.gov (United States)

    Zhao, Jing; Wang, Mei; Fu, Aiyun; Yang, Hongfang; Bu, Yuxiang

    2015-08-03

    We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped hydrated electron state to a hydrated 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 hydrated electron no longer transfers to NBs, our AIMD simulations indicate that a fully hydrated electron can still transfer to NBs. We monitored the transfer dynamics of fully hydrated electrons towards hydrated NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully hydrated electron can transfer to a NB gradually over time. Concurrently, the hydrated 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 hydrated 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 hydrated NB anion. Clearly, the observed transfer of hydrated electrons can be attributed to the strong electron-binding ability of hydrated NBs over the hydrated 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 hydrated electrons and provides some helpful information for understanding the DNA-damage mechanism in solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hydrate Phase Assemblages in Blends of Ye'elimite and Gypsum with Alite and Belite

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Skibsted, Jørgen

    2016-01-01

    Calcium sulpho-aluminate (CSA) cements all contain ye’elimite, either as the main phase or in intermediate amounts, while they differ in their content of accessory phases. Belite is the main phase in most CSA cements, however, alite - CSA cements have been produced. The hydrate phases formed during...... and hydration kinetics. The improved understanding of the hydrate phase assemblages as well as the hydration kinetics for the model systems will form the fundamental basis for further optimizations of blended systems including ye’elimite with the aim of maximizing the reaction degree of the main clinker phases...... hydration of CSA cements depend on the type of CSA cement and the amount of gypsum added. The hydration reactions of the main phases are by themselves well documented, whereas the simultaneous hydration of CSA cement components is not fully understood in terms of hydration products and kinetics. To further...

  5. First-principles elasticity of monocarboaluminate hydrates

    KAUST Repository

    Moon, J.

    2014-07-01

    The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

  6. First-principles elasticity of monocarboaluminate hydrates

    KAUST Repository

    Moon, J.; Yoon, S.; Wentzcovitch, R. M.; Monteiro, P. J. M.

    2014-01-01

    The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

  7. Hydration rate of obsidian.

    Science.gov (United States)

    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.

  8. Methods for Additive Hydration Allowing Observation of Fully Hydrated State of Wet Samples in Environmental SEM

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém

    2007-01-01

    Roč. 70, č. 2 (2007), s. 95-100 ISSN 1059-910X R&D Projects: GA ČR(CZ) GA102/05/0886; GA AV ČR KJB200650602 Institutional research plan: CEZ:AV0Z20650511 Keywords : agar * natural structure * biological specimens * environmental SEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.644, year: 2007

  9. Methane Hydrates: Chapter 8

    Science.gov (United States)

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

    2008-01-01

    Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

  10. Chemical alteration of cement hydrates by dissolution

    International Nuclear Information System (INIS)

    Sugiyama, Daisuke; Fujita, Tomonari; Nakanishi, Kiyoshi

    2000-01-01

    Cementitious material is a potential waste packaging and backfilling material for the radioactive waste disposal, and is expected to provide both physical and chemical containment. In particular, the sorption of radionuclides onto cementitious material and the ability to provide a high pH condition are very important parameters when considering the release of radionuclides from radioactive wastes. For the long term, in the geological disposal environment, cement hydrates will be altered by, for example, dissolution, chemical reaction with ions in the groundwater, and hydrothermal reaction. Once the composition or crystallinity of the constituent minerals of a cement hydrate is changed by these processes, the pH of the repository buffered by cementitious material and its sorption ability might be affected. However, the mechanism of cement alteration is not yet fully understood. In this study, leaching experiments of some candidate cements for radioactive waste disposal were carried out. Hydrated Ordinary Portland Cement (OPC), Blast Furnace Slag blended cement (OPC/BFS) and Highly containing Flyash and Silicafume Cement (HFSC) samples were contacted with distilled water at liquid:solid ratios of 10:1, 100:1 and 1000:1 at room temperature for 200 days. In the case of OPC, Ca(OH) 2 dissolved at high liquid:solid ratios. The specific surface area of all cement samples increased by leaching process. This might be caused by further hydration and change of composition of constituent minerals. A model is presented which predicts the leaching of cement hydrates and the mineral composition in the hydrated cement solid phase, including the incongruent dissolution of CSH gel phases and congruent dissolution of Ca(OH) 2 , Ettringite and Hydrotalcite. Experimental results of dissolution of Ca-O-H and Ca-Si-O-H phases were well predicted by this model. (author)

  11. India National Gas Hydrate Program Expedition 02 Technical Contributions

    Science.gov (United States)

    Collett, T. S.; Kumar, P.; Shukla, K. M.; Nagalingam, J.; Lall, M. V.; Yamada, Y.; Schultheiss, P. J.; Holland, M.; Waite, W. F.

    2017-12-01

    The National Gas Hydrate Program Expedition 02 (NGHP-02) was conducted from 3-March-2015 to 28-July-2015 off the eastern coast of India. The primary objective of this expedition was the exploration and discovery of highly saturated gas hydrate occurrences in sand reservoirs that would be targets of future production testing. The first 2 months of the expedition were dedicated to logging while drilling (LWD) operations with a total of 25 holes being drilled and logged. The next 3 months were dedicated to coring operations at 10 of the most promising sites. NGHP-02 downhole logging, coring and formation pressure testing have confirmed the presence of large, highly saturated, gas hydrate accumulations in coarse-grained sand-rich depositional systems throughout the Krishna-Godavari Basin within the regions defined during NGHP-02 as Area-B, Area-C, and Area-E. The nature of the discovered gas hydrate occurrences closely matched pre-drill predictions, confirming the project developed depositional models for the sand-rich depositional facies in the Krishna-Godavari and Mahanadi Basins. The existence of a fully developed gas hydrate petroleum system was established in Area-C of the Krishna-Godavari Basin with the discovery of a large slope-basin interconnected depositional system, including a sand-rich, gas-hydrate-bearing channel-levee prospect at Sites NGHP-02-08 and -09. The acquisition of closely spaced LWD and core holes in the Area-B L1 Block gas hydrate accumulation have provided one of the most complete three-dimensional petrophysical-based views of any known gas hydrate reservoir system in the world. It was concluded that Area-B and Area-C in the area of the greater Krishna-Godavari Basin contain important world-class gas hydrate accumulations and represent ideal sites for consideration of future gas hydrate production testing.

  12. HYDRATE CORE DRILLING TESTS

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. Experimental setting for assessing mechanical strength of gas hydrate pellet

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, S.J.; Choi, J.H.; Koh, B.H. [Dongguk Univ., Phil-dong, Chung-gu, Seoul (Korea, Republic of). Dept. of Mechanical Engineering

    2008-07-01

    Due to the constant increase in global demand for clean energy, natural gas production from stranded medium and small size gas wells has drawn significant interest. Because the ocean transport of natural gas in the form of solid hydrate pellets (NGHP) has been estimated to be economically feasible, several efforts have been made to develop a total NGHP ocean transport chain. The investigation of mechanical strength of solid-form hydrate pellet has been an important task in fully exploiting the benefit of gas hydrate in the perspective of mass transportation and storage. This paper provided the results of a preliminary study regarding the assessment of mechanical properties of the gas hydrate pellet. The preliminary study suggested some of the key issues regarding formation and strength of gas hydrate pellets. Instead of utilizing the gas hydrate pellet, the study focused on a preliminary test setup for developing the ice pellet which was readily applied to the gas hydrate pellet in the future. The paper described the pelletization of ice powder as well as the experimental setup. Several photographs were illustrated, including samples of ice pellets; compression test for ice pellet using air press and load cell; and the initiation of crack in the cross section of an ice pellet. It was found that mechanical strength, especially, compression strength was not significantly affected by different level of press-forming force up to a certain level. 4 refs., 1 tab., 4 figs.

  14. Phosphate vibrations as reporters of DNA hydration

    Science.gov (United States)

    Corcelli, Steven

    The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

  15. Overview: Nucleation of clathrate hydrates.

    Science.gov (United States)

    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.

  16. Formation of submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

    1994-03-01

    Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

  17. Overview: Nucleation of clathrate hydrates

    Science.gov (United States)

    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.

  18. Dehydration behaviour of hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Dette, S.S.; Stelzer, T.; Jones, M.J.; Ulrich, J. [Martin-Luther-Universitaet Halle-Wittenberg, Zentrum fuer Ingenieurwissenschaften, Verfahrenstechnik/TVT, 06099 Halle (Germany)

    2010-07-15

    Immersing a crystalline solvate in a suitable anti-solvent can induce phase transformation to solvent-free solid phase. In certain cases the solvent-mediated phase transition results in the generation of hollow, tubular structures. Both the tube dimensions of sodium-2-keto-L-gulonate anhydrate (skga) and the dehydration kinetics of sodium-2-keto-L-gulonate monohydrate (skgm) can be modified by the antisolvent employed. An explanation for the variable dehydration behaviour of skgm in the antisolvents is presented here. Furthermore, other crystalline hydrates were dehydrated in dry methanol. Providing an operational window can be found, any hydrate material could possibly find use in the production of tubes (micro- or nanotubes for different applications). The experimental conditions selected (dry methanol as antisolvent, dehydration temperature at 25 C) for the dehydration did not lead to the anhydrate tube growth for all hydrates investigated. Based upon the results presented here a first hypothesis is presented to explain this effect. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Measurement of ambient aerosol hydration state at Great Smoky Mountains National Park in the southeastern United States

    Directory of Open Access Journals (Sweden)

    N. F. Taylor

    2011-12-01

    Full Text Available We present results from two field deployments of a unique tandem differential mobility analyzer (TDMA configuration with two primary capabilities: identifying alternative stable or meta-stable ambient aerosol hydration states associated with hysteresis in aerosol hydration behavior and determining the actual Ambient hydration State (AS-TDMA. This data set is the first to fully classify the ambient hydration state of aerosols despite recognition that hydration state significantly impacts the roles of aerosols in climate, visibility and heterogeneous chemistry. The AS-TDMA was installed at a site in eastern Tennessee on the border of Great Smoky Mountains National Park for projects during the summer of 2006 and winter of 2007–2008. During the summer, 12% of the aerosols sampled in continuous AS-TDMA measurements were found to posses two possible hydration states under ambient conditions. In every case, the more hydrated of the possible states was occupied. The remaining 88% did not posses multiple possible states. In continuous measurements during the winter, 49% of the aerosols sampled possessed two possible ambient hydration states; the remainder possessed only one. Of those aerosols with multiple possible ambient hydration states, 65% occupied the more hydrated state; 35% occupied the less hydrated state. This seasonal contrast is supported by differences in the fine particulate (PM2.5 composition and ambient RH as measured during the two study periods. In addition to seasonal summaries, this work includes case studies depicting the variation of hydration state with changing atmospheric conditions.

  20. Gas hydrate cool storage system

    Science.gov (United States)

    Ternes, M.P.; Kedl, R.J.

    1984-09-12

    The invention presented relates to the development of a process utilizing a gas hydrate 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 hydrate as storage material in a thermal energy storage system within a heat pump cycle system. The gas hydrate was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)

  1. THERMODYNAMIC MODEL OF GAS HYDRATES

    OpenAIRE

    Недоступ, В. И.; Недоступ, О. В.

    2015-01-01

    The interest to gas hydrates grows last years. Therefore working out of reliable settlement-theoretical methods of definition of their properties is necessary. The thermodynamic model of gas hydrates in which the central place occupies a behaviour of guest molecule in cell is described. The equations of interaction of molecule hydrate formative gas with cell are received, and also an enthalpy and energy of output of molecule from a cell are determined. The equation for calculation of thermody...

  2. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina; Yamauchi, Kazuo; Li, Zongjin; Zhang, Xixiang; Ma, Hongyan; Ge, Shenguang

    2017-01-01

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10

  3. Fully portable blood irradiator

    International Nuclear Information System (INIS)

    Hungate, F.P.; Riemath, W.F.; Bunnell, L.R.

    1980-01-01

    A fully portable blood irradiator was developed using the beta emitter thulium-170 as the radiation source and vitreous carbon as the body of the irradiator, matrix for isotope encapsulation, and blood interface material. These units were placed in exteriorized arteriovenous shunts in goats, sheep, and dogs and the effects on circulating lymphocytes and on skin allograft retention times measured. The present work extends these studies by establishing baseline data for skin graft rejection times in untreated animals

  4. Hydrate-CASM for modeling Methane Hydrate-Bearing Sediments

    Science.gov (United States)

    De La Fuente Ruiz, M.; Vaunat, J.; Marin Moreno, H.

    2017-12-01

    A clear understanding of the geomechanical behavior of methane hydrate-bearing sediments (MHBS) is crucial to assess the stability of the seafloor and submarine infrastructures to human and natural loading changes. Here we present the Hydrate-CASM, a new elastoplastic constitutive model to predict the geomechanical behavior of MHBS. Our model employs the critical state model CASM (Clay and Sand Model) because of its flexibility in describing the shape of the yield surface and its proven ability to predict the mechanical behavior of sands, the most commercially viable hydrate reservoirs. The model considers MHBS as a deformable elastoplastic continuum, and hydrate-related changes in the stress-strain behavior are predicted by a densification mechanism. The densification attributes the mechanical contribution of hydrate to; a reduction of the available void ratio; a decrease of the swelling line slope; and an increase of the volumetric yield stress. It is described by experimentally derived physical parameters except from the swelling slope coefficient that requires empirical calibration. The Hydrate-CASM is validated against published triaxial laboratory tests performed at different confinement stresses, hydrate saturations, and hydrate morphologies. During the validation, we focused on capturing the mechanical behavior of the host sediment and consider perturbations of the sediment's mechanical properties that could result from the sample preparation. Our model successfully captures the experimentally observed influence of hydrate saturation in the magnitude and trend of the stiffness, shear strength, and dilatancy of MHBS. Hence, we propose that hydrate-related densification changes might be a major factor controlling the geomechanical response of MHBS.

  5. TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Moridis, George J.; Kowalsky, Michael B.; Pruess, Karsten

    2008-03-01

    TOUGH+HYDRATE v1.0 is a new code for the simulation of the behavior of hydrate-bearing geologic systems. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH{sub 4}-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYDRATE v1.0 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH{sub 4}, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects. TOUGH+HYDRATE is the first member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available.

  6. Thermal properties of methane hydrate by experiment and modeling and impacts upon technology

    Energy Technology Data Exchange (ETDEWEB)

    Warzinski, R.P.; Gamwo, I.K.; Rosenbaum, E.J. [United States Dept. of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory; Myshakin, E.M. [NETL Support Contractor, South Park, PA (United States); Jiang, H.; Jordan, K.D. [Pittsburgh Univ., Pittsburgh, PA (United States). Dept. of Chemistry; English, N.J. [Dublin University College, Dublin (Ireland). Conway Inst. of Biomolecular and Biomedical Research, Centre for Synthesis and Chemical Biology; Shaw, D.W. [Geneva College, Beaver Falls, PA (United States). Dept. of Engineering

    2008-07-01

    The current hydrate research at the National Energy Technology Laboratory (NETL) involves both experimental and theoretical work on developing models and methods for predicting the behaviour of gas hydrates in their natural environment under production of climate change scenarios. The modeling efforts include both fundamental and reservoir scale simulations and economic modeling. The thermal properties of methane hydrate are important for hydrate production, seafloor stability and climate change scenarios. A new experimental technique and advanced molecular dynamics simulation (MDS) have determined the thermal properties of pure methane hydrate under conditions similar to naturally occurring hydrate-bearing sediments. The thermal conductivity and thermal diffusivity values of low-porosity methane hydrate formed in the laboratory were measured using an innovative single-sided, Transient Plane Source (TPS) technique. The results were in good agreement with results from an equilibrium MDS method using in-plane polarization of the water molecules. MDS was also performed using a non-equilibrium model with a fully polarizable force field for water. The Tough+Hydrate reservoir simulator was also used to evaluate the impact of thermal conductivity on gas production from a hydrate-bearing reservoir. 42 refs., 1 tab., 5 figs.

  7. Ductile flow of methane hydrate

    Science.gov (United States)

    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.

  8. Flow assurance intervention, hydrates remediation

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, Christopher S. [Oceaneering International Inc., Houston, TX (United States)

    2012-07-01

    This paper addresses the issues of removing hydrates in sub sea flow lines and associated equipment with an Remotely Operated Vehicle (ROV) of opportunity and a multi-service-vessel (MSV). The paper is split into three topics: the equipment used with the ROV, assessing the interface points and handling fluids produced from drawing down the pressure. Each section is explained thoroughly and backed up with real world experience. The equipment section details information from actual jobs performed and why the particular components were utilized. The system is generally contained in an ROV mounted skid. Pumps are utilized to draw down the pressure inside the hydrated section of equipment, removing one of the three necessary components for hydrates formation. Once the section is pumped down, several options exist for handling the fluids pumped out of the system: pumping to surface, re-injection into the well, or injection into an operating flow line. This method of hydrates remediation is both economical and timely. Hydrate blockages form in low temperatures and high pressures. Reducing the pressure or increasing the temperature so the conditions lie to the right of the hydrate dissociation curve will slowly decompose the blockage. Depressurization and the use of MEG or methanol will give favorable conditions to remove the hydrate plug. Oceaneering has the capabilities to remove hydrates using the FRS in conjunction with an installation vessel to dispose of the gas and fluid removed from the flow line. Hydrate remediation techniques should be implemented into the initial design to reduce costs later. The cost of stopped production combined with the day rate for equipment needed for hydrate removal outweighs the costs if no technique is utilized. (author)

  9. Android Fully Loaded

    CERN Document Server

    Huddleston, Rob

    2012-01-01

    Fully loaded with the latest tricks and tips on your new Android! Android smartphones are so hot, they're soaring past iPhones on the sales charts. And the second edition of this muscular little book is equally impressive--it's packed with tips and tricks for getting the very most out of your latest-generation Android device. Start Facebooking and tweeting with your Android mobile, scan barcodes to get pricing and product reviews, download your favorite TV shows--the book is positively bursting with practical and fun how-tos. Topics run the gamut from using speech recognition, location-based m

  10. Calcium Aluminate Cement Hydration Model

    Directory of Open Access Journals (Sweden)

    Matusinović, T.

    2011-01-01

    Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

  11. Shifting Focus: From Hydration for Performance to Hydration for Health.

    Science.gov (United States)

    Perrier, Erica T

    2017-01-01

    Over the past 10 years, literature on hydration biomarkers has evolved considerably - from (de)hydration assessment towards a more global definition of biomarkers of hydration in daily life. This shift in thinking about hydration 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 hydration for performance, toward hydration for health outcomes. This narrative review outlines the key areas of research in which the global hydration process - including water intake, urinary hydration markers, and vasopressin - has been associated with health outcomes, focusing on kidney and metabolic endpoints. It will also provide a commentary on how various hydration biomarkers may be used in hydration 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 hydration. However, there remain a large number of incomplete or unanswered research questions regarding the

  12. The temperature hydration kinetics

    Directory of Open Access Journals (Sweden)

    Mircea Oroian

    2017-07-01

    Full Text Available The aim of this study is to evaluate the hydration kinetics of lentil seeds (Lens culinaris in water at different temperatures (25, 32.5, 40, 55, 70 and 80 °C for assessing the adequacy of models for describing the absorption phenomena during soaking. The diffusion coefficient values were calculated using Fick’s model for spherical and hemispherical geometries and the values were in the range of 10−6 m2/s. The experimental data were fitted to Peleg, Sigmoidal, Weibull and Exponential models. The models adequacy was determined using regression coefficients (R2, root mean square error (RMSE and reduced chi-square (χ2. The Peleg model is the suitable one for predicting the experimental data. Temperature had a positive and significant effect on the water absorption capacities and absorption was an endothermic process.

  13. Alcohol cosurfactants in hydrate antiagglomeration.

    Science.gov (United States)

    York, J Dalton; Firoozabadi, Abbas

    2008-08-28

    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 hydrates formed from coproduced water and hydrate-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 hydrate 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 hydrate inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are antiagglomerants, which prevent agglomeration of small hydrate crystallites. Despite great potential, work on hydrate 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 hydrate-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 hydrate 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 hydrate slurries down to 0.01 wt. %. However, biochemical surfactants are less toxic and biodegradable, and thus their use may prove beneficial even if at

  14. TOUGH+HYDRATE v1.2 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kowalsky, Michael B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pruess, Karsten [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    TOUGH+HYDRATE v1.2 is a code for the simulation of the behavior of hydratebearing geologic systems, and represents the second update of the code since its first release [Moridis et al., 2008]. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH4-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy’s law is valid. TOUGH+HYDRATE v1.2 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH4, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects. TOUGH+HYDRATE is a member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95/2003, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available.

  15. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration 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 hydration 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 hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration 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.

  16. Coupled numerical modeling of gas hydrates bearing sediments from laboratory to field-scale conditions

    Science.gov (United States)

    Sanchez, M. J.; Santamarina, C.; Gai, X., Sr.; Teymouri, M., Sr.

    2017-12-01

    Stability and behavior of Hydrate Bearing Sediments (HBS) are characterized by the metastable character of the gas hydrate structure which strongly depends on thermo-hydro-chemo-mechanical (THCM) actions. Hydrate formation, dissociation and methane production from hydrate bearing sediments are coupled THCM processes that involve, amongst other, exothermic formation and endothermic dissociation of hydrate and ice phases, mixed fluid flow and large changes in fluid pressure. The analysis of available data from past field and laboratory experiments, and the optimization of future field production studies require a formal and robust numerical framework able to capture the very complex behavior of this type of soil. A comprehensive fully coupled THCM formulation has been developed and implemented into a finite element code to tackle problems involving gas hydrates sediments. Special attention is paid to the geomechanical behavior of HBS, and particularly to their response upon hydrate dissociation under loading. The numerical framework has been validated against recent experiments conducted under controlled conditions in the laboratory that challenge the proposed approach and highlight the complex interaction among THCM processes in HBS. The performance of the models in these case studies is highly satisfactory. Finally, the numerical code is applied to analyze the behavior of gas hydrate soils under field-scale conditions exploring different features of material behavior under possible reservoir conditions.

  17. Effect of gas hydrates melting on seafloor slope stability

    Science.gov (United States)

    Sultan, N.; Cochonat, P.; Foucher, J. P.; Mienert, J.; Haflidason, H.; Sejrup, H. P.

    2003-04-01

    Quantitative studies of kinetics of gas hydrate formation and dissociation is of a particular concern to the petroleum industry for an evaluation of environmental hazards in deep offshore areas. Gas hydrate dissociation can generate excess pore pressure that considerably decreases the strength of the soil. In this paper, we present a theoretical study of the thermodynamic chemical equilibrium of gas hydrate in soil, which is based on models previously reported by Handa (1989), Sloan (1998) and Henry (1999). Our study takes into account the influence of temperature, pressure, pore water chemistry, and the pore size distribution of the sediment. This model fully accounts for the latent heat effects, as done by Chaouch and Briaud (1997) and Delisle et al. (1998). It uses a new formulation based on the enthalpy form of the law of conservation of energy. The model allows for the evaluation of the excess pore pressure generated during gas hydrate dissociation using the Soave’s (1972) equation of state. Fluid flow in response to the excess pore pressure is simulated using the finite element method. In the second part of the paper, we present and discuss an application of the model through a back-analysis of the case of the giant Storegga slide on the Norwegian margin. Two of the most important changes during and since the last deglaciation (hydrostatic pressure due to the change of the sea level and the increase of the sea water temperature) were considered in the calculation. Simulation results are presented and discussed. Chaouch, A., &Briaud, J.-L., 1997. Post melting behavior of gas hydrates in soft ocean sediments, OTC-8298, in 29th offshore technology conference proceedings, v. 1, Geology, earth sciences and environmental factors: Society of Petroleum Engineers, p. 217-224. Delisle, G.; Beiersdorf, H.; Neben, S.; Steinmann, D., 1998. The geothermal field of the North Sulawesi accretionary wedge and a model on BSR migration in unstable depositional environments. in

  18. Fully electric waste collection

    CERN Multimedia

    Anaïs Schaeffer

    2015-01-01

    Since 15 June, Transvoirie, which provides waste collection services throughout French-speaking Switzerland, has been using a fully electric lorry for its collections on the CERN site – a first for the region!   Featuring a motor powered by electric batteries that charge up when the brakes are used, the new lorry that roams the CERN site is as green as can be. And it’s not only the motor that’s electric: its waste compactor and lifting mechanism are also electrically powered*, making it the first 100% electric waste collection vehicle in French-speaking Switzerland. Considering that a total of 15.5 tonnes of household waste and paper/cardboard are collected each week from the Meyrin and Prévessin sites, the benefits for the environment are clear. This improvement comes as part of CERN’s contract with Transvoirie, which stipulates that the firm must propose ways of becoming more environmentally friendly (at no extra cost to CERN). *The was...

  19. Hydration water and microstructure in calcium silicate and aluminate hydrates

    International Nuclear Information System (INIS)

    Fratini, Emiliano; Ridi, Francesca; Chen, Sow-Hsin; Baglioni, Piero

    2006-01-01

    Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C 3 S, C 2 S) and aluminates (C 3 A, C 4 AF) were studied by quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and near-infrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm -1 monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the 1 H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small angle neutron scattering (USANS) and wide

  20. Hydration dependent dynamics in RNA

    International Nuclear Information System (INIS)

    Olsen, Greg L.; Bardaro, Michael F.; Echodu, Dorothy C.; Drobny, Gary P.; Varani, Gabriele

    2009-01-01

    The essential role played by local and collective motions in RNA function has led to a growing interest in the characterization of RNA dynamics. Recent investigations have revealed that even relatively simple RNAs experience complex motions over multiple time scales covering the entire ms-ps motional range. In this work, we use deuterium solid-state NMR to systematically investigate motions in HIV-1 TAR RNA as a function of hydration. We probe dynamics at three uridine residues in different structural environments ranging from helical to completely unrestrained. We observe distinct and substantial changes in 2 H solid-state relaxation times and lineshapes at each site as hydration levels increase. By comparing solid-state and solution state 13 C relaxation measurements, we establish that ns-μs motions that may be indicative of collective dynamics suddenly arise in the RNA as hydration reaches a critical point coincident with the onset of bulk hydration. Beyond that point, we observe smaller changes in relaxation rates and lineshapes in these highly hydrated solid samples, compared to the dramatic activation of motion occurring at moderate hydration

  1. Mechanism of gypsum hydration

    Directory of Open Access Journals (Sweden)

    Pacheco, G.

    1991-06-01

    Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

    En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

  2. Reconsideration on Hydration of Sodium Ion: From Micro-Hydration to Bulk Hydration

    Science.gov (United States)

    Yongquan, Zhou; Chunhui, Fang; Yan, Fang; Fayan, Zhu; Haiwen, Ge; Hongyan, Liu

    2017-12-01

    Micro hydration structures of the sodium ion, [Na(H2O) n ]+, n = 1-12, were probed by density functional theory (DFT) at B3LYP/aug-cc-pVDZ level in both gaseous and aqueous phase. The predicted equilibrium sodium-oxygen distance of 0.240 nm at the present level of theory. The four-, five- and six-coordinated cluster can transform from each other at the ambient condition. The analysis of the successive water binding energy and natural charge population (NBO) on Na+ clearly shows that the influence of Na+ on the surrounding water molecules goes beyond the first hydration shell with the hydration number of 6. The Car-Parrinello molecular dynamic simulation shows that only the first hydration sphere can be found, and the hydration number of Na+ is 5.2 and the hydration distance ( r Na-O) is 0.235 nm. All our simulations mentioned in the present paper show an excellent agreement with the diffraction result from X-ray scattering study.

  3. A high yield process for hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Giavarini, C.; Maccioni, F. [Univ. of Roma La Sapienza, Roma (Italy). Dept. of Chemical Engineering

    2008-07-01

    Due to the large quantities of natural gas stored in deep ocean hydrates, hydrate reservoirs are a substantial energy resource. Hydrates concentrate methane by as much as a factor of 164. As such, several natural gas transportation and storage systems using gas hydrates have been studied, and many of them are nearing practical use. In these systems, the hydrate is produced as a slurry by a spray process at approximately 7 megapascal (MPa), and then shaped into pellets. The use of a spray process, instead of a conventional stirred vessel is necessary in order to reach high hydrate concentrations in the hydrate-ice system. This paper presented a new procedure to produce a bulk of concentrated methane hydrate in a static traditional reactor at moderate pressure, controlling pressure and temperature in the interval between ice melting and the hydrate equilibrium curve. This paper discussed the experimental procedure which included formation of methane hydrate at approximately 5 MPa and 2 degrees Celsius in a reaction calorimeter at a volume of two liters. Results were also discussed. It was concluded that the procedure seemed suitable for the development of a gas hydrate storage and transport technology. It was found that the spray procedure took more time, but could be sped up and made continuous by using two vessels, one for hydrate formation and the other for hydrate concentration. The advantage was the production of a concentrated hydrate, using a simpler equipment and working at lower pressures respect to the spray process. 9 refs., 5 figs.

  4. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.

    1999-01-01

    and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6......Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...

  5. Storage capacity of hydrogen in gas hydrates

    International Nuclear Information System (INIS)

    Tsuda, Takaaki; Ogata, Kyohei; Hashimoto, Shunsuke; Sugahara, Takeshi; Sato, Hiroshi; Ohgaki, Kazunari

    2010-01-01

    The storage capacity of H 2 in the THF, THT, and furan hydrates was studied by p-V-T measurements. We confirmed that the storage and release processes of H 2 in all hydrates could be performed reversibly by pressure swing without destroying of hydrate cages. H 2 absorption in both THT and furan hydrates is much faster than THF hydrate in spite of same unit-cell structure. On the other hand, the storage amounts of H 2 are coincident in the all additive hydrates and would reach at about 1.0 mass% asymptotically.

  6. Cage occupancies of natural gas hydrates encaging methane and ethane

    Energy Technology Data Exchange (ETDEWEB)

    Kida, M.; Hachikubo, A.; Sakagami, H.; Minami, H.; Krylov, A.; Yamashita, S.; Takahashi, N.; Shoji, H. [Kitami Inst. of Technology, Kitami (Japan); Kida, M. [National Inst. of Advanced Industrial Science and Technology, Toyohira-ku, Sapporo (Japan); Khlystov, O. [Limnological Inst., Irkutsk (Russian Federation). Siberian Branch of the Russian Academy of Sciences; Poort, J. [Ghent Univ., Ghent (Belgium). Renard Centre of Marine Geology; Narita, H. [National Inst. of Advanced Industrial Science and Technology, Toyohira-ku, Sapporo (Japan)

    2008-07-01

    Natural gas hydrates are crystalline compounds that contain large amounts of natural gas in its structure and are expected to provide natural gas resources in the future. The gas species are trapped in different types of polyhedral cages which consist of hydrogen bonded water molecules. Three main types of crystallographic structures exist, notably structure 1, structure 2 and structure H (sH). The crystallographic structure of natural gas hydrates depends on the encaged gas components. The cage occupancy is the ratio of the number of cages occupied by guest molecules to the number of total cages. It is also important to estimate the amount of natural gas, since it depends on the condition of the hydrate formation such as gas composition. The cages of natural gas hydrates mainly contain methane. However, other heavier hydrocarbons such as ethane (C{sub 2}H{sub 6}), propane (C{sub 3}H{sub 8}), and isobutane (i-C{sub 4}H{sub 1}0) may be encaged together with CH{sub 4}. Little is known about cage occupancies of natural gas hydrates including CH{sub 4} and heavier hydrocarbons. This paper discussed a study that developed cage occupancy estimations of natural gas hydrates encaging heavier hydrocarbons. 13C nuclear magnetic resonance (NMR) measurements were conducted. The assignments of resonance lines were based on 13C chemical shifts obtained by artificial sample measurements. The paper presented the experimental data and discussed the results of the study. The large cages were almost fully occupied with CH{sub 4} and C{sub 2}H{sub 6} molecules, whereas the small cage occupancies of CH{sub 4} were below 0.8. The distribution of CH{sub 4} and C{sub 2}H{sub 6} in each cage were similar to that of synthetic CH{sub 4} + C{sub 2}H{sub 6} hydrate. It was concluded that these results should be useful for optimal estimation of the amount of natural gas in gas hydrates. 18 refs., 1 tab., 3 figs.

  7. Gas hydrates forming and decomposition conditions analysis

    Directory of Open Access Journals (Sweden)

    А. М. Павленко

    2017-07-01

    Full Text Available The concept of gas hydrates has been defined; their brief description has been given; factors that affect the formation and decomposition of the hydrates have been reported; their distribution, structure and thermodynamic conditions determining the gas hydrates formation disposition in gas pipelines have been considered. Advantages and disadvantages of the known methods for removing gas hydrate plugs in the pipeline have been analyzed, the necessity of their further studies has been proved. In addition to the negative impact on the process of gas extraction, the hydrates properties make it possible to outline the following possible fields of their industrial use: obtaining ultrahigh pressures in confined spaces at the hydrate decomposition; separating hydrocarbon mixtures by successive transfer of individual components through the hydrate given the mode; obtaining cold due to heat absorption at the hydrate decomposition; elimination of the open gas fountain by means of hydrate plugs in the bore hole of the gushing gasser; seawater desalination, based on the hydrate ability to only bind water molecules into the solid state; wastewater purification; gas storage in the hydrate state; dispersion of high temperature fog and clouds by means of hydrates; water-hydrates emulsion injection into the productive strata to raise the oil recovery factor; obtaining cold in the gas processing to cool the gas, etc.

  8. Methods to determine hydration states of minerals and cement hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2014-11-15

    This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.

  9. Methods to determine hydration states of minerals and cement hydrates

    International Nuclear Information System (INIS)

    Baquerizo, Luis G.; Matschei, Thomas; Scrivener, Karen L.; Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars

    2014-01-01

    This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na 2 SO 4 –H 2 O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions

  10. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina

    2017-05-13

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

  11. Impacts of Hydrate Distribution on the Hydro-Thermo-Mechanical Properties of Hydrate-Bearing Sediments

    Science.gov (United States)

    Dai, S.; Seol, Y.

    2015-12-01

    In general, hydrate makes the sediments hydraulically less conductive, thermally more conductive, and mechanically stronger; yet the dependency of these physical properties on hydrate saturation varies with hydrate distribution and morphology. Hydrate distribution in sediments may cause the bulk physical properties of their host sediments varying several orders of magnitude even with the same amount of hydrate. In natural sediments, hydrate morphology is inherently governed by the burial depth and the grain size of the host sediments. Compare with patchy hydrate, uniformly distributed hydrate is more destructive to fluid flow, yet leads to higher gas and water permeability during hydrate dissociation due to the easiness of forming percolation paths. Water and hydrate have similar thermal conductivity values; the bulk thermal conductivity of hydrate-bearing sediments depends critically on gas-phase saturation. 60% of gas saturation may result in evident thermal conductivity drop and hinder further gas production. Sediments with patchy hydrate yield lower stiffness than that with cementing hydrate but higher stiffness than that with pore filling and loading bearing hydrate. Besides hydrate distribution, the stress state and loading history also play an important role in the mechanical behavior of hydrate-bearing sediments.

  12. Multipartite fully nonlocal quantum states

    International Nuclear Information System (INIS)

    Almeida, Mafalda L.; Cavalcanti, Daniel; Scarani, Valerio; Acin, Antonio

    2010-01-01

    We present a general method for characterizing the quantum correlations obtained after local measurements on multipartite systems. Sufficient conditions for a quantum system to be fully nonlocal according to a given partition, as well as being (genuinely) multipartite fully nonlocal, are derived. These conditions allow us to identify all completely connected graph states as multipartite fully nonlocal quantum states. Moreover, we show that this feature can also be observed in mixed states: the tensor product of five copies of the Smolin state, a biseparable and bound entangled state, is multipartite fully nonlocal.

  13. Is Br2 hydration hydrophobic?

    Science.gov (United States)

    Alcaraz-Torres, A; Gamboa-Suárez, A; Bernal-Uruchurtu, M I

    2017-02-28

    The spectroscopic properties of bromine in aqueous systems suggest it can behave as either hydrophilic or hydrophobic solute. In small water clusters, the halogen bond and the hydrogen-halogen interaction are responsible for its specific way of binding. In water hydrates, it is efficiently hosted by two different cages forming the crystal structure and it has been frequently assumed that there is little or no interaction between the guest and the host. Bromine in liquid solution poses a challenging question due to its non-negligible solubility and the large blue shift measured in its absorption spectra. Using a refined semi-empirical force field, PM3-PIF, we performed a Born-Oppenheimer molecular dynamics study of bromine in liquid water. Here we present a detailed study in which we retrieved the most representative hydration structures in terms of the most frequent positions around bromine and the most common water orientations. Albeit being an approximate description of the total hydration phenomenon, it captures the contribution of the leading molecular interactions in form of the recurrent structures. Our findings confirm that the spectroscopic signature is mainly caused by the closest neighbors. The dynamics of the whole first hydration shell strongly suggests that the external molecules in that structure effectively isolate the bulk from the presence of bromine. The solvation structure fluctuates from a hydrophilic to a hydrophobic-like environment along the studied trajectory.

  14. Hydration modeling of calcium sulphates

    NARCIS (Netherlands)

    de Korte, A.C.J.; Brouwers, H.J.H.; Al-Mattarneh, Hashem; Mustapha, Kamal N.; Nuruddin, Muhd Fadhil

    2008-01-01

    The CEMHYD3D model has been extended at the University of Twente in the last ten years [1,2]. At present the cement hydration model is extended for the use of gypsum. Although gypsum was present in the model already, the model was not suitable for high contents of gypsum and did not include the

  15. Influence of smectite hydration and swelling on atrazine sorption behavior.

    Science.gov (United States)

    Chappell, Mark A; Laird, David A; Thompson, Michael L; Li, Hui; Teppen, Brian J; Aggarwal, Vaneet; Johnston, Cliff T; Boyd, Stephen A

    2005-05-01

    Smectites, clay minerals commonly found in soils and sediments, vary widely in their ability to adsorb organic chemicals. Recent research has demonstrated the importance of surface charge density and properties of exchangeable cations in controlling the affinity of smectites for organic molecules. In this study, we induced hysteresis in the crystalline swelling of smectites to test the hypothesis that the extent of crystalline swelling (or interlayer hydration status) has a large influence on the ability of smectites to adsorb atrazine from aqueous systems. Air-dried K-saturated Panther Creek (PC) smectite swelled less (d(001) = 1.38 nm) than never-dried K-PC (d(001) = 1.7 nm) when rehydrated in 20 mM KCl. Correspondingly, the air-dried-rehydrated K-PC had an order of magnitude greater affinity for atrazine relative to the never-dried K-PC. Both air-dried-rehydrated and never-dried Ca-PC expanded to approximately 2.0 nm in 10 mM CaCl2 and both samples had similar affinities for atrazine that were slightly lower than that of never-dried K-PC. The importance of interlayer hydration status in controlling sorption affinity was confirmed by molecular modeling, which revealed much greater interaction between interlayer water molecules and atrazine in a three-layer hydrate relative to a one-layer hydrate. The entropy change on moving atrazine from a fully hydrated state in the bulk solution to a partially hydrated state in the smectite interlayers is believed to be a major factor influencing sorption affinity. In an application test, choice of background solution (20 mM KCl versus 10 mM CaCl2) and air-drying treatments significantly affected atrazine sorption affinities for three-smectitic soils; however, the trends were not consistent with those observed for the reference smectite. Further, extending the initial rehydration time from 24 to 240 h (prior to adding atrazine) significantly decreased the soil's sorption affinity for atrazine. We conclude that interlayer

  16. Observed gas hydrate morphologies in marine sediment

    Energy Technology Data Exchange (ETDEWEB)

    Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)

    2008-07-01

    The morphology of gas hydrate in marine sediments determines the basic physical properties of the sediment-hydrate matrix and provides information regarding the formation of gas hydrate deposits, and the nature of the disruption that will occur on dissociation. Small-scale morphology is useful in estimating the concentrations of gas hydrate from geophysical data. It is also important for predicting their response to climate change or commercial production. Many remote techniques for gas hydrate detection and quantification depend on hydrate morphology. In this study, morphology of gas hydrate was examined in HYACINTH pressure cores from recent seagoing expeditions. Visual and infrared observations from non-pressurized cores were also used. The expeditions and pressure core analysis were described in detail. This paper described the difference between two types of gas hydrate morphologies, notably pore-filling and grain-displacing. Last, the paper addressed the impact of hydrate morphology. It was concluded that a detailed morphology of gas hydrate is an essential component for a full understanding of the past, present, and future of any gas hydrate environment. 14 refs., 4 figs.

  17. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K

    1996-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  18. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K.

    1995-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  19. Influence of fluorosurfactants on hydrate formation rates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.U.; Jeong, K.E.; Chae, H.J.; Jeong, S.Y. [Korea Reasearch Inst. of Chemical Technology, Alternative Chemicals/Fuel Research Center, Yuseong-Gu, Daejon (Korea, Republic of)

    2008-07-01

    Gas hydrates, or clathrates, are ice-like solids that forms when natural gas is in contact with liquid water or ice under high pressure and low temperature. There is significant interest in studying the storage and transportation of gas in the form of hydrates. However, a critical problem impacting the industrial application of gas hydrates for storage and transportation of natural gas is the slow formation rate of natural gas hydrate. Researchers have previously reported on the promotion effect of some additives on gas hydrate formation and hydrate gas content. Fluorosurfactants are significantly superior to nonfluorinated surfactants in wetting action, as well as stability in harsh environments, both thermal and chemical. This paper discussed an experimental investigation into the effects of fluorosurfactants with different ionic types on the formation of methane hydrate. The surfactants used were FSN-100 of DuPont Zonyl as non-ionic surfactant and FC-143 of DuPont as anionic surfactant. The paper discussed the experimental apparatus for methane hydrate formation. It also discussed hydrate formation kinetics and the series of hydrate formation experiments that were conducted in the presence of fluorosurfactants. Last, the paper explored the results of the study. It was concluded that anionic fluorosurfactant of FC-143 had a better promoting effect on methane hydrate formation compared with nonionic surfactant of FSN-100. 8 refs., 2 tabs., 2 figs.

  20. Lattice constants of pure methane and carbon dioxide hydrates at low temperatures. Implementing quantum corrections to classical molecular dynamics studies

    Energy Technology Data Exchange (ETDEWEB)

    Costandy, Joseph; Michalis, Vasileios K.; Economou, Ioannis G., E-mail: i.tsimpanogiannis@qatar.tamu.edu, E-mail: ioannis.economou@qatar.tamu.edu [Chemical Engineering Program, Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Tsimpanogiannis, Ioannis N., E-mail: i.tsimpanogiannis@qatar.tamu.edu, E-mail: ioannis.economou@qatar.tamu.edu [Chemical Engineering Program, Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Environmental Research Laboratory, National Center for Scientific Research NCSR “Demokritos,” 15310 Aghia Paraskevi, Attikis (Greece); Stubos, Athanassios K. [Environmental Research Laboratory, National Center for Scientific Research NCSR “Demokritos,” 15310 Aghia Paraskevi, Attikis (Greece)

    2016-03-28

    We introduce a simple correction to the calculation of the lattice constants of fully occupied structure sI methane or carbon dioxide pure hydrates that are obtained from classical molecular dynamics simulations using the TIP4PQ/2005 water force field. The obtained corrected lattice constants are subsequently used in order to obtain isobaric thermal expansion coefficients of the pure gas hydrates that exhibit a trend that is significantly closer to the experimental behavior than previously reported classical molecular dynamics studies.

  1. Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

    Science.gov (United States)

    Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

    2010-01-01

    The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

  2. Dynamics of Permafrost Associated Methane Hydrate in Response to Climate Change

    Science.gov (United States)

    You, K.; Flemings, P. B.

    2014-12-01

    The formation and melting of methane hydrate and ice are intertwined in permafrost regions. A shortage of methane supply leads to formation of hydrate only at depth, below the base of permafrost. We consider a system with the ground surface initially at 0 oC with neither ice nor hydrate present. We abruptly decrease the temperature from 0 to -10 oC to simulate the effect of marine regression/ global cooling. A low methane supply rate of 0.005 kg m-2 yr-1 from depth leads to distinct ice and hydrate layers: a 100 m continuous hydrate layer is present beneath 850 m at 80 k.y.. However, a high methane supply rate of 0.1 kg m-2 yr-1 leads to 50 m ice-bonded methane hydrate at the base of permafrost, and the hydrate layer distributes between the depth of 350 and 700 m at 80 k.y.. We apply our model to illuminate future melting of hydrate at Mallik, a known Arctic hydrate accumulation. We assume a 600 m thick ice saturated (average 90%) layer extending downward from the ground surface. We increase the surface temperature linearly from -6 to 0 oC for 300 yr and then keep the surface temperature at 0 oC to reflect future climate warming caused by doubling of CO2. Hydrate melting is initiated at the base of the hydrate layer after 15 k.y.. Methane gas starts to vent to the atmosphere at 38 k.y. with an average flux of ~ 0.35 g m-2 yr-1. If the 600 m thick average ice saturation is decreased to half (45%) (or to zero), methane gas starts to vent to the atmosphere at 29 k.y. (or at 20 k.y.) with the same average flux. These results are found by a newly-developed fully-coupled multiphase multicomponent fluid flow and heat transport model. Our thermodynamic equilibrium-based model emphasizes the role of salinity in both ice and hydrate dynamics.

  3. Fire extinction utilizing carbon dioxide hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Hatakeyama, T.; Aida, E.; Yokomori, T.; Ohmura, R.; Ueda, T. [Keio Univ., Hiyoshi, Kohoku-ku, Yokohama (Japan)

    2008-07-01

    Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because dissociation of the hydrates results in the temperature decrease in the combustion field and the nonflammable gases released from the dissociated hydrates prevent the supply of the oxygen to the combustion field. This paper discussed experiments in which ordinary ice and dry ice were used to evaluate the performance of CO{sub 2} hydrate as a fire extinguishing agent. The paper described the apparatus and procedure for the preparation of CO{sub 2} hydrate crystals. A schematic of the reactor to form CO{sub 2} hydrate and a photograph of CO{sub 2} hydrate crystal formed in the study were also presented. Other illustrations, photographs, and tables that were presented included a schematic diagram of the experimental apparatus used for the flame extinction experiments; a photograph of CO{sub 2} hydrate powder; sequential video graphs of the flame extinction by the supply of CO{sub 2} hydrate crystals to the methanol pool flame and the relevant illustration; and heat of CO{sub 2} hydrate dissociation, water vaporization and sublimation of dry ice. It was concluded that the critical mass of the CO{sub 2} hydrate required to extinguish a flame was much less than that of ordinary ice, indicating the superiority of CO{sub 2} hydrate to the ice. In addition, the experiments also revealed that the size of the CO{sub 2} hydrate particles had a significant effect on the performance of flame extinction. 5 refs., 2 tabs., 7 figs.

  4. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  5. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn D.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate–saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate–bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

  6. Physical Properties of Gas Hydrates: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge [Prairie View A& M University; Tsouris, Costas [ORNL

    2010-01-01

    Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately 1016?m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.

  7. Accelerated hydration of high silica cements

    International Nuclear Information System (INIS)

    Walker, Colin; Yui, Mikazu

    2012-01-01

    Current Japanese designs for high level radioactive waste (HLW) repositories anticipate the use of both bentonite (buffer and backfill material) and cement based materials. Using hydrated Ordinary Portland Cement (OPC) as a grouting material is undesirable because the associated high pH buffer will have an undisputed detrimental effect on the performance of the bentonite buffer and backfill and of the host rock by changing its porosity. Instead, hydrated low pH cement (LopHC) grouting materials are being developed to provide a pH inferior or equal to 11 to reduce these detrimental effects. LopHC grouting materials use mixtures of superfine OPC (SOPC) clinker and silica fume (SF), and are referred as high silica cements (HSC). The focus of the present study was to identify the development of the unhydrated and hydrated mineral assemblage and the solution chemistry during the hydration of HSC. Since hydration experiments of cementitious materials are notably slow, a ball mill was used to accelerate hydration. This was done for two reasons. Firstly, to develop a method to rapidly hydrate cement based materials without the need for higher temperatures (which can alter the mineral assemblage), and secondly, to ensure that the end point of hydration was reached in a reasonable time frame and so to realize the final mineralogy and solution chemistry of hydrated HSC

  8. Microstructure of natural hydrate host sediments

    International Nuclear Information System (INIS)

    Jones, K.W.; Kerkar, P.B.; Mahajan, D.; Lindquist, W.B.; Feng, H.

    2007-01-01

    There is worldwide interest in the study of natural gas hydrate because of its potential impact on world energy resources, control on seafloor stability, significance as a drilling hazard and probable impact on climate as a reservoir of a major greenhouse gas. Gas hydrates can (a) be free floating in the sediment matrix (b) contact, but do not cement, existing sediment grains, or (c) actually cement and stiffen the bulk sediment. Seismic surveys, often used to prospect for hydrates over a large area, can provide knowledge of the location of large hydrate concentrations because the hydrates within the sediment pores modify seismic properties. The ability to image a sample at the grain scale and to determine the porosity, permeability and seismic profile is of great interest since these parameters can help in determining the location of hydrates with certainty. We report here on an investigation of the structure of methane hydrate sediments at the grain-size scale using the synchrotron radiation-based computed microtomography (CMT) technique. Work has started on the measurements of the changes occurring as tetrahydrofuran hydrate, a surrogate for methane hydrate, is formed in the sediment

  9. Application of empirical hydration distribution functions around polar atoms for assessing hydration structures of proteins

    International Nuclear Information System (INIS)

    Matsuoka, Daisuke; Nakasako, Masayoshi

    2013-01-01

    Highlights: ► Empirical distribution functions of water molecules in protein hydration are made. ► The functions measure how hydrogen-bond geometry in hydration deviate from ideal. ► The functions assess experimentally identified hydration structures of protein. - Abstract: To quantitatively characterize hydrogen-bond geometry in local hydration structures of proteins, we constructed a set of empirical hydration distribution functions (EHDFs) around polar protein atoms in the main and side chains of 11 types of hydrophilic amino acids (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 113 (2009) 11274). The functions are the ensemble average of possible hydration patterns around the polar atoms, and describe the anisotropic deviations from ideal hydrogen bond geometry. In addition, we defined probability distribution function of hydration water molecules (PDFH) over the hydrophilic surface of a protein as the sum of EHDFs of solvent accessible polar protein atoms. The functions envelop most of hydration sites identified in crystal structures of proteins (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 114 (2010) 4652). Here we propose the application of EHDFs and PDFHs for assessing crystallographically identified hydration structures of proteins. First, hydration water molecules are classified with respect to the geometry in hydrogen bonds in referring EHDFs. Difference Fourier electron density map weighted by PDFH of protein is proposed to identify easily density peaks as candidates of hydration water molecules. A computer program implementing those ideas was developed and used for assessing hydration structures of proteins

  10. Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

    Science.gov (United States)

    Barlag, Rebecca; Nyasulu, Frazier

    2011-01-01

    The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

  11. Physics of fully ionized regions

    International Nuclear Information System (INIS)

    Flower, D.

    1975-01-01

    In this paper the term fully ionised regions is taken to embrace both planetary nebulae and the so-called 'H II' regions referred to as H + regions. Whilst these two types of gaseous nebulae are very different from an evolutionary standpoint, they are physically very similar, being characterised by photoionisation of a low-density plasma by a hot star. (Auth.)

  12. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Monteiro Cristiano Ralo

    2003-01-01

    Full Text Available Hydration should be considered before, during and after the exercise. This review intends to approach the main points of hydration process in soccer. The replacement of fluids during exercise is proportional to some factors, such as: exercise intensity; climatic conditions; the athlete's acclimatization; the athlete's physical conditioning; physiologic individual characteristics and the player's biomechanics. Performance is improved when players ingest not only water but also carbohydrate. The rates that carbohydrate and water are absorbed by the organism are limited by the rates of gastric emptying and intestinal absorption. The composition of drinks offered to the players should be influenced by the relative importance of the need of supplying carbohydrates or water; it should be remembered that the depletion of carbohydrate can result in fatigue and decrease of performance, but it is not usually a life-threatening condition. The addition of carbohydrate in these drinks increases the concentrations of blood glucose, increases the use of external fuel through the increase of the glucose oxidation in the muscles and it spares muscle glycogen. So, the ingestion of carbohydrate before and during the exercise can delay the emergence of fatigue and increase the players' performance. Several tactics can be used to avoid dehydration, like hyperhydration before exercise and player's acclimatization. The ideal situation to restore the player's fluid losses is between the sessions of exercises. Since soccer is a sport with quite peculiar characteristics related to hydration, the players should be concerned and educated about the importance of fluid ingestion before, during and after the exercise.

  13. Gas Hydrates | Alaska Division of Geological & Geophysical Surveys

    Science.gov (United States)

    Preliminary Report - Cascadia Margin Gas Hydrates, Volume 204 Initial Report Mallik 2002 GSC Bulletin 585 : Scientific results from the Mallik 2002 gas hydrate production well program Offshore gas hydrate sample

  14. Simulation and Characterization of Methane Hydrate Formation

    Science.gov (United States)

    Dhakal, S.; Gupta, I.

    2017-12-01

    The ever rising global energy demand dictates human endeavor to explore and exploit new and innovative energy sources. As conventional oil and gas reserves deplete, we are constantly looking for newer sources for sustainable energy. Gas hydrates have long been discussed as the next big energy resource to the earth. Its global occurrence and vast quantity of natural gas stored is one of the main reasons for such interest in its study and exploration. Gas hydrates are solid crystalline substances with trapped molecules of gas inside cage-like crystals of water molecules. Gases such as methane, ethane, propane and carbon dioxide can form hydrates but in natural state, methane hydrates are the most common. Subsurface geological conditions with high pressure and low temperature favor the formation and stability of gas hydrates. While the occurrence and potential of gas hydrates as energy source has long been studied, there are still gaps in knowledge, especially in the quantitative research of gas hydrate formation and reservoir characterization. This study is focused on exploring and understanding the geological setting in which gas hydrates are formed and the subsequent changes in rock characteristics as they are deposited. It involves the numerical simulation of methane gas flow through fault to form hydrates. The models are representative of the subsurface geologic setting of Gulf of Mexico with a fault through layers of shale and sandstone. Hydrate formation simulated is of thermogenic origin. The simulations are conducted using TOUGH+HYDRATE, a numerical code developed at the Lawrence Berkley National Laboratory for modeling multiphase flow through porous medium. Simulation results predict that as the gas hydrates form in the pores of the model, the porosity, permeability and other rock properties are altered. Preliminary simulation results have shown that hydrates begin to form in the fault zone and gradually in the sandstone layers. The increase in hydrate

  15. Formation rate of natural gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Mork, Marit

    2002-07-01

    The rate of methane hydrate and natural gas hydrate formation was measured in a 9.5 litre stirred tank reactor of standard design. The experiments were performed to better understand the performance and scale-up of a reactor for continuous production of natural gas hydrates. The hydrate formation rate was measured at steady-state conditions at pressures between 70 and 90 bar and temperatures between 7 and 15 deg C. Between 44 and 56 % of the gas continuously supplied to the reactor was converted to hydrate. The experimental results show that the rate of hydrate formation is strongly influenced by gas injection rate and pressure. The effect of stirring rate is less significant and subcooling has no observable effect on the formation rate. Hydrate crystal concentration and gas composition do not influence the hydrate formation rate. Observations of produced hydrate crystals indicate that the crystals are elongated, about 5 micron in diameter and 10 micron long. Analysis of the results shows that the rate of hydrate formation is dominated by gas-liquid mass transfer. A mass transfer model, the bubble-to-crystal model, was developed for the hydrate formation rate in a continuous stirred tank reactor, given in terms of concentration driving force and an overall mass transfer coefficient. The driving force is the difference between the gas concentration at the gas-liquid interface and at the hydrate crystal surface. These concentrations correspond to the solubility of gas in water at experimental temperature and pressure and the solubility of gas at hydrate equilibrium temperature and experimental pressure, respectively. The overall mass transfer coefficient is expressed in terms of superficial gas velocity and impeller power consumption, parameters commonly used in study of stirred tank reactors. Experiments and modeling show that the stirred tank reactor has a considerable potential for increased production capacity. However, at higher hydrate production rates the

  16. Hydration-coupled protein boson peak measured by incoherent neutron scattering

    International Nuclear Information System (INIS)

    Nakagawa, Hiroshi; Kataoka, Mikio; Joti, Yasumasa; Kitao, Akio; Shibata, Kaoru; Tokuhisa, Atsushi; Tsukushi, Itaru; Go, Nobuhiro

    2006-01-01

    The boson peak of a protein was examined in relation to hydration using staphylococcal nuclease. Although the boson peak is commonly observed in synthetic polymers, glassy materials and amorphous materials, the origin of the boson peak is not fully understood. The motions that contribute to the peak are harmonic vibrations. Upon hydration the peak frequency shifts to a higher frequency and the effective force constant of the vibration increases at low temperatures, suggesting that the protein energy surface is modified. Hydration of the protein leads to a more rugged surface and the vibrational motions are trapped within the local minimum at cryogenic temperatures. The origin of the protein boson peak may be related to this rugged energy surface

  17. The Exchange Reaction Between Methane Hydrate and Carbon Dioxide: An Oceanic Feasibility Test

    Science.gov (United States)

    Dunk, R. M.; Brewer, P. G.; Peltzer, E. T.; Walz, P. M.; Hester, K. C.; Sloan, E. D.

    2006-12-01

    The conversion of CH4 hydrate to CO2 hydrate offers, in principle, a way of sequestering CO2, with the additional recovery of CH4 gas as an energy source. We report results from the first in-situ oceanic experiment on this reaction, carried out in August 2006 at the massive thermogenic hydrate mounds in 850 m water depth, Barkley Canyon, offshore from Vancouver Island (48° 18.642' N, 126° 3.903' W), using MBARI's ROV Tiburon deployed from the R/V Western Flyer. Two small cores (10 cm length, 4 cm diameter) of white hydrate were collected from exposed outcrops using an ROV operated tool and hydraulically ejected into a glass walled, closed top, reaction chamber. Approximately 2 L of liquid CO2 were dispensed into the chamber, and the chamber transferred to an aluminium base plate to seal the system. Under ambient conditions (P = 870 dbar, T = 4.0 °C, S = 34.2), the densities of natural gas hydrate and liquid CO2 are closely matched and less than that of seawater, where the hydrate cores floated at the top of the chamber fully immersed within the buoyant liquid CO2. Over the following ~48 hours, the system was inspected periodically with the ROV HDTV camera prior to examination with the sea-going laser Raman spectrometer, DORISS II. For this, the chamber was transferred to a Precision Underwater Positioner (PUP) that enabled focusing of the laser beam with sub- mm precision. Our choice of where to focus the laser was based upon the need to explore all phases the cored natural gas hydrate, liquid CO2, any created CO2 hydrate, and any liberated CH4 gas. The natural gas hydrate was composed primarily of CH4, with minor amounts of C2H6 and C3H8, indicating the presence of Structure II hydrate. To date, laboratory experiments have focused on the reaction between pure Structure I CH4 hydrate and CO2 vapour, where the difference in free energy between the CH4 and CO2 hydrate states provides a thermodynamic argument in favour of conversion. However for a Structure II

  18. Free energy of hydration of niobium oxide

    International Nuclear Information System (INIS)

    Plodinec, M.J.

    1996-01-01

    Some of the glasses being formulated by SRTC researchers contain niobium oxide. In this report, the free energy of hydration of the oxide is calculated from the free energies of formation of the oxide, the hydroxide, and water. This value can be used in calculations of the free energy of hydration of glasses containing niobium

  19. Investigations into surfactant/gas hydrate relationship

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

    2007-03-15

    Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

  20. 75 FR 9886 - Methane Hydrate Advisory Committee

    Science.gov (United States)

    2010-03-04

    ... DEPARTMENT OF ENERGY Methane Hydrate Advisory Committee AGENCY: Department of Energy, Office of Fossil Energy. ACTION: Notice of open meeting. SUMMARY: This notice announces a meeting of the Methane... the Committee: The purpose of the Methane Hydrate Advisory Committee is to provide advice on potential...

  1. Raman Spectroscopic Studies of Methane Gas Hydrates

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.

    2009-01-01

    A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

  2. Multicomponent modelling of Portland cement hydration reactions

    NARCIS (Netherlands)

    Ukrainczyk, N.; Koenders, E.A.B.; Van Breugel, K.

    2012-01-01

    The prospect of cement and concrete technologies depends on more in depth understanding of cement hydration reactions. Hydration reaction models simulate the development of the microstructures that can finally be used to estimate the cement based material properties that influence performance and

  3. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  4. Experimental Setup to Characterize Bentonite Hydration Processes

    International Nuclear Information System (INIS)

    Bru, A.; Casero, D.; Pastor, J. M.

    2001-01-01

    We present an experimental setup to follow-up the hydration process of a bentonite. Clay samples, of 2 cm x 12 cm x 12 cm, were made and introduced in a Hele-Shaw cell with two PMM windows and two steel frames. In hydration experiments, a fluid enters by an orifice in the frame, located both at the top and the bottom of the cell, to perform hydration in both senses. To get a uniform hydration we place a diffuser near the orifice. Volume influxes in hydration cells are registered in time. The evolution of the developed interface was recorded on a videotape. The video cameras was fixed to a holder so that the vertical direction in the monitor was the same as the direction of the larger extension of the cell. (Author) 6 refs

  5. Volume of hydration in terminal cancer patients.

    Science.gov (United States)

    Bruera, E; Belzile, M; Watanabe, S; Fainsinger, R L

    1996-03-01

    In this retrospective study we reviewed the volume and modality of hydration of consecutive series of terminal cancer patients in two different settings. In a palliative care unit 203/290 admitted patients received subcutaneous hydration for 12 +/- 8 days at a daily volume of 1015 +/- 135 ml/day. At the cancer center, 30 consecutive similar patients received intravenous hydration for 11.5 +/- 5 days (P > 0.2) but at a daily volume of 2080 +/- 720 ml/day (P palliative care unit patients required discontinuation of hydration because of complications. Hypodermoclysis was administered mainly as a continuous infusion, an overnight infusion, or in one to three 1-h boluses in 62 (31%), 98 (48%) and 43 (21%) patients, respectively. Our findings suggest that, in some settings, patients may be receiving excessive volumes of hydration by less comfortable routes such as the intravenous route. Increased education and research in this area are badly needed.

  6. Hydration shells exchange charge with their protein

    DEFF Research Database (Denmark)

    Abitan, Haim; Lindgård, Per-Anker; Nielsen, Bjørn Gilbert

    2010-01-01

    . In our experiments, the amplitude of an ultrasonic pressure wave is gradually increased (0–20 atm) while we simultaneously measure the Raman spectra from the hydrated protein (β-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity......Investigation of the interaction between a protein and its hydration shells is an experimental and theoretical challenge. Here, we used ultrasonic pressure waves in aqueous solutions of a protein to explore the conformational states of the protein and its interaction with its hydration shells...... the presence of an ultrasonic pressure, a protein and its hydration shells are in thermodynamic and charge equilibrium, i.e. a protein and its hydration shells exchange charges. The ultrasonic wave disrupts these equilibria which are regained within 30–45 min after the ultrasonic pressure is shut off....

  7. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

  8. Gas Hydrate Storage of Natural Gas

    Energy Technology Data Exchange (ETDEWEB)

    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

  9. Material Research on Salt Hydrates for Seasonal Heat Storage Application in a Residential Environment

    Energy Technology Data Exchange (ETDEWEB)

    Ferchaud, C.J.; Zondag, H.A.; De Boer, R. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2013-09-15

    Water vapor sorption in salt hydrates is a promising method to realize seasonal solar heat storage in the residential sector. Several materials already showed promising performance for this application. However, the stability of these materials needs to be improved for long-term (30 year) application in seasonal solar heat storages. The purpose of this article is to identify the influence of the material properties of the salt hydrates on the performance and the reaction kinetics of the sorption process. The experimental investigation presented in this article shows that the two salt hydrates Li2SO4.H2O and CuSO4.5H2O can store and release heat under the operating conditions of a seasonal solar heat storage in a fully reversible way. However, these two materials show differences in terms of energy density and reaction kinetics. Li2SO4.H2O can release heat with an energy density of around 0.80 GJ/m{sup 3} within 4 hours of rehydration at 25C, while CuSO4.5H2O needs around 130 hours at the same temperature to be fully rehydrated and reaches an energy density of 1.85 GJ/m{sup 3}. Since the two salts are dehydrated and hydrated under the same conditions, this difference in behavior is directly related to the intrinsic properties of the materials.

  10. Can hydrate dissolution experiments predict the fate of a natural hydrate system?

    Energy Technology Data Exchange (ETDEWEB)

    Hester, K.C.; Peltzer, E.T.; Dunk, R.M.; Walz, P.M.; Brewer, P.G. [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Dendy Sloan, E. [Colorado School of Mines, Golden, CO (United States). Center for Hydrate Research

    2008-07-01

    Gas hydrates are naturally occurring compounds found in permafrost regions and in oceans. In the natural environment, sufficient temperature and pressure conditions for hydrate formation exist over a significant portion of the ocean. However, in addition to pressure and temperature, the chemical potential of the gas in the hydrate must be equal to the surrounding waters. If the concentration of the gas in surrounding water is under-saturated with respect to the gas in the hydrate, the hydrate will dissolve to drive the system towards chemical equilibrium. This paper presented a dissolution study of exposed hydrate from outcrops at Barkley Canyon, located off Vancouver Island, British Columbia. A previous field experiment on synthetic methane hydrate samples had demonstrated that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have significant longevity compared to expected dissolution rates based upon convective boundary layer diffusion calculations. An in-situ dissolution experiment was performed on two distinct natural hydrate fabrics in order to help resolve this apparent disconnect between the dissolution rates of synthetic and natural hydrate. The paper presented a map of Barkley Canyon and discussed the field measurements and methods for the study. Exposed outcrops of gas hydrates were cored using a specially constructed stainless steel coring device and a hydraulic ram was located inside the corer. Hydrate samples were cored directly using the a manipulator arm and then injected into a sampling cell. The hydrate was then added to an open mesh exposure container, which allowed for exposure to ambient benthic currents with minimal disturbance. As well, in order to observe the slow dissolution of the hydrate in seawater at Barkley Canyon, time-lapse photography was employed. Last, the paper presented the results of the hydrate fabric porosities and hydrate dissolution rates. It was

  11. Axiomatisation of fully probabilistic design

    Czech Academy of Sciences Publication Activity Database

    Kárný, Miroslav; Kroupa, Tomáš

    2012-01-01

    Roč. 186, č. 1 (2012), s. 105-113 ISSN 0020-0255 R&D Projects: GA MŠk(CZ) 2C06001; GA ČR GA102/08/0567 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bayesian decision making * Fully probabilistic design * Kullback–Leibler divergence * Unified decision making Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 3.643, year: 2012 http://library.utia.cas.cz/separaty/2011/AS/karny-0367271.pdf

  12. Hydration Properties of Ground Granulated Blast-Furnace Slag (GGBS Under Different Hydration Environments

    Directory of Open Access Journals (Sweden)

    Shuhua LIU

    2017-02-01

    Full Text Available The hydration properties of various cementitious materials containing Ground Granulated Blast-furnace Slag (GGBS, two alkali-activated slag cements (AAS-1 and AAS-2 in which sodium silicate and sodium hydroxide act as alkaline activators respectively, supersulfated cement (SSC and slag Portland cement(PSC, are compared with ordinary Portland cement (OPC to investigate the effect of activating environment on the hydration properties in this study by determining the compressive strength of the pastes, the hydration heat of binders within 96 hours, and the hydration products at age of 28 days. The results show that C-S-H gels are the main hydrated products for all cementitious systems containing GGBS. Ca(OH2 is the hydration products of OPC and PSC paste. However, ettringite and gypsum crystals instead of Ca(OH2 are detected in SSC paste. Additionally, tobermorite, a crystalline C-S-H, and calcite are hydrated products in AAS-1. Tobermorite, cowlesite and calcite are hydrated products of AAS-2 as well. Based on strength results, AAS-1 paste exhibits the highest compressive strength followed by POC, PSC, SSC in order at all testing ages and AAS-2 give the lowest compressive strength except for the early age at 3 days, which is higher than SSC but still lower than PSC. From hydration heat analysis, alkalinity in the reaction solution is a vital factor influencing the initial hydration rate and the initial hydration rate from higher to lower is AAS-2, AAS-1, OPC, PSC and SSC. Although AAS possesses a faster reaction rate in the initial hours, cumulative hydration heat of AAS is comparably lower than that of OPC, but higher than those of PSC and SSC in turn, which indicates that the hydration heat of clinkers is much higher than that of slag.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14934

  13. Calcium and magnesium silicate hydrates

    International Nuclear Information System (INIS)

    Lothenbach, B.; L'Hopital, E.; Nied, D.; Achiedo, G.; Dauzeres, A.

    2015-01-01

    Deep geological disposals are planed to discard long-lived intermediate-level and high-level radioactive wastes. Clay-based geological barriers are expected to limit the ingress of groundwater and to reduce the mobility of radioelements. In the interaction zone between the cement and the clay based material alteration can occur. Magnesium silicate hydrates (M-S-H) have been observed due to the reaction of magnesium sulfate containing groundwater with cements or in the interaction zone between low-pH type cement and clays. M-S-H samples synthesized in the laboratory showed that M-S-H has a variable composition within 0.7 ≤ Mg/Si ≤ 1.5. TEM/EDS analyses show an homogeneous gel with no defined structure. IR and 29 Si NMR data reveal a higher polymerization degree of the silica network in M-S-H compared to calcium silicate hydrates (C-S-H). The presence of mainly Q 3 silicate tetrahedrons in M-S-H indicates a sheet like or a triple-chain silica structure while C-S-H is characterised by single chain-structure. The clear difference in the silica structure and the larger ionic radius of Ca 2+ (1.1 Angstrom) compared to Mg 2+ (0.8 Angstrom) make the formation of an extended solid solution between M-S-H and C-S-H gel improbable. In fact, the analyses of synthetic samples containing both magnesium and calcium in various ratios indicate the formation of separate M-S-H and C-S-H gels with no or very little uptake of magnesium in CS-H or calcium in M-S-H

  14. Basics of development of gas hydrate deposits

    Energy Technology Data Exchange (ETDEWEB)

    Makogon, Yuri F.; Holditch, Stephen A.; Makogon, Taras Y.

    2005-07-01

    Natural gas hydrate deposits could possibly be an important energy resource during this century. However, many problems associated with producing these deposits must first be solved. The industry must develop new technologies to produce the gas, to forecast possible tectonic cataclysms in regions of gas hydrate accumulations, and to prevent damage to the environment. These global issues must be addressed by every company or country who wants to produce gas hydrate deposits. Cooperative research between industry and universities can lead to technology breakthroughs in coming years. This paper reviews the Messoyakha field and the Blake Ridge and Nankai areas to explain a methodology for estimating how much gas might be producible from gas hydrate deposits (GHDs) under various conditions. The Messoyakha field is located on land, while the Blake Ridge and Nankai areas are offshore. Messoyakha is the first and the only GHD where gas production from hydrates has reached commercial flow rates. The Blake Ridge GHD has been studied for 20 years and 11 wells have been drilled to collect gas-hydrate samples. The potential resources of gas (gas in place) from Blake Ridge is estimated at 37.7Oe10{sup 12} m{sup 3} (1.330 Tcf) in hydrate form and 19.3Oe10{sup 12}m{sup 3} (681 Bcf) [5] in free gas. To estimate how much of the potential resource can be produced we need a thorough understanding of both the geologic and the thermodynamic characteristics of the formations. (Author)

  15. Gas hydrate exploration activities in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Keun-Pil Park, K.P. [Korea Inst. of Geoscience and Mineral Resources, Gas Hydrate R and D Organization, Ministry of Knowledge Economy, Yuseong-gu, Daejeon (Korea, Republic of)

    2008-07-01

    Korea's first gas hydrate research project was launched in 1996 to study the gas hydrate potential in the Ulleung Basin of the East Sea. It involved a series of laboratory experiments followed by a preliminary offshore seismic survey and regional reconnaissance geophysical and marine geological surveys. The bottom simulating reflector (BSR) was interpreted to show wide area distribution in the southern part of the Ulleung Basin, and its average burial depth was 187 m below the sea floor in the East Sea. A three-phase 10-year National Gas Hydrate Development Program was launched in 2004 to estimate the potential reserves in the East Sea. It will involve drilling to identify natural gas hydrates and to determine the most optimized production methods. Drilling sites were proposed based on five indicators that imply gas hydrate occurrence, notably BSR, gas vent, enhanced seismic reflection, acoustic blanking and gas seeping structure. The UBGH-X-01 gas hydrate expedition in the East Sea Ulleung Basin involved 5 logging while drilling (LWD) surveys at three high priority sites. One wire line logging was implemented at the site of the UBGH09. A total 334 m of non-pressurized conventional cores and 16 pressure cores were obtained in late 2007. The UBGH-X-01 was successfully completed, recovering many natural samples of gas hydrate from 3 coring sites in the East Sea. 7 refs., 12 figs.

  16. Gas Hydrates Research Programs: An International Review

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2009-12-09

    Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource. There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration. The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included.

  17. Physics of fully depleted CCDs

    International Nuclear Information System (INIS)

    Holland, S E; Bebek, C J; Kolbe, W F; Lee, J S

    2014-01-01

    In this work we present simple, physics-based models for two effects that have been noted in the fully depleted CCDs that are presently used in the Dark Energy Survey Camera. The first effect is the observation that the point-spread function increases slightly with the signal level. This is explained by considering the effect on charge-carrier diffusion due to the reduction in the magnitude of the channel potential as collected signal charge acts to partially neutralize the fixed charge in the depleted channel. The resulting reduced voltage drop across the carrier drift region decreases the vertical electric field and increases the carrier transit time. The second effect is the observation of low-level, concentric ring patterns seen in uniformly illuminated images. This effect is shown to be most likely due to lateral deflection of charge during the transit of the photo-generated carriers to the potential wells as a result of lateral electric fields. The lateral fields are a result of space charge in the fully depleted substrates arising from resistivity variations inherent to the growth of the high-resistivity silicon used to fabricate the CCDs

  18. Supramolecular Organization of Nonstoichiometric Drug Hydrates: Dapsone

    Science.gov (United States)

    Braun, Doris E.; Griesser, Ulrich J.

    2018-01-01

    The observed moisture- and temperature dependent transformations of the dapsone (4,4′-diaminodiphenyl sulfone, DDS) 0. 33-hydrate were correlated to its structure and the number and strength of the water-DDS intermolecular interactions. A combination of characterization techniques was used, including thermal analysis (hot-stage microscopy, differential scanning calorimetry and thermogravimetric analysis), gravimetric moisture sorption/desorption studies and variable humidity powder X-ray diffraction, along with computational modeling (crystal structure prediction and pair-wise intermolecular energy calculations). Depending on the relative humidity the hydrate contains between 0 and 0.33 molecules of water per molecule DDS. The crystal structure is retained upon dehydration indicating that DDS hydrate shows a non-stoichiometric (de)hydration behavior. Unexpectedly, the water molecules are not located in structural channels but at isolated-sites of the host framework, which is counterintuitively for a hydrate with non-stoichiometric behavior. The water-DDS interactions were estimated to be weaker than water-host interactions that are commonly observed in stoichiometric hydrates and the lattice energies of the isomorphic dehydration product (hydrate structure without water molecules) and (form III) differ only by ~1 kJ mol−1. The computational generation of hypothetical monohydrates confirms that the hydrate with the unusual DDS:water ratio of 3:1 is more stable than a feasible monohydrate structure. Overall, this study highlights that a deeper understanding of the formation of hydrates with non-stoichiometric behavior requires a multidisciplinary approach including suitable experimental and computational methods providing a firm basis for the development and manufacturing of high quality drug products. PMID:29520359

  19. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-07-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  20. Tapping methane hydrates for unconventional natural gas

    Science.gov (United States)

    Ruppel, Carolyn

    2007-01-01

    Methane hydrate is an icelike form of concentrated methane and water found in the sediments of permafrost regions and marine continental margins at depths far shallower than conventional oil and gas. Despite their relative accessibility and widespread occurrence, methane hydrates have never been tapped to meet increasing global energy demands. With rising natural gas prices, production from these unconventional gas deposits is becoming economically viable, particularly in permafrost areas already being exploited for conventional oil and gas. This article provides an overview of gas hydrate occurrence, resource assessment, exploration, production technologies, renewability, and future challenges.

  1. On the electrolytic generation of hydrated electron

    International Nuclear Information System (INIS)

    Ghosh Mazumdar, A.S.; Guha, S.N.

    1975-01-01

    Investigations on the electrolytic generation of hydrated electron in oxygenated as well as oxygen-free solutions at different pH were undertaken. Since sup(-e)aq is known to react rapidly with O 2 yielding the transient O 2 - ion, the latter was looked for through its interaction with phosphite ions resulting in their oxidation near the cathode. It appears from the results that in electrolytic processes, the primary electron (esup(-)sub(cathode)) probably reacts directly with reactive solutes like oxygen, bypassing the hydration step. Data obtained in oxygen-free solutions, however, support the possible formation of hydrated electron at least in alkaline solutions. (author)

  2. Experimental Investigation of Effect on Hydrate Formation in Spray Reactor

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhao

    2015-01-01

    Full Text Available The effects of reaction condition on hydrate formation were conducted in spray reactor. The temperature, pressure, and gas volume of reaction on hydrate formation were measured in pure water and SDS solutions at different temperature and pressure with a high-pressure experimental rig for hydrate formation. The experimental data and result reveal that additives could improve the hydrate formation rate and gas storage capacity. Temperature and pressure can restrict the hydrate formation. Lower temperature and higher pressure can promote hydrate formation, but they can increase production cost. So these factors should be considered synthetically. The investigation will promote the advance of gas storage technology in hydrates.

  3. Gas hydrate concentration and characteristics within Hydrate Ridge inferred from multicomponent seismic reflection data

    Science.gov (United States)

    Kumar, Dhananjay; Sen, Mrinal K.; Bangs, Nathan L.

    2007-12-01

    A seismic experiment composed of streamer and ocean bottom seismometer (OBS) surveys was conducted in the summer of 2002 at southern Hydrate Ridge, offshore Oregon, to map the gas hydrate distribution within the hydrate stability zone. Gas hydrate concentrations within the reservoir can be estimated with P wave velocity (Vp); however, we can further constrain gas hydrate concentrations using S wave velocity (Vs), and use Vs through its relationship to Vp (Vp/Vs) to reveal additional details such as gas hydrate form within the matrix (i.e., hydrate cements the grains, becomes part of the matrix frame or floats in pore space). Both Vp and Vs can be derived simultaneously by inverting multicomponent seismic data. In this study, we use OBS data to estimate seismic velocities where both gas hydrate and free gas are present in the shallow sediments. Once Vp and Vs are estimated, they are simultaneously matched with modeled velocities to estimate the gas hydrate concentration. We model Vp using an equation based on a modification of Wood's equation that incorporates an appropriate rock physics model and Vs using an empirical relation. The gas hydrate concentration is estimated to be up to 7% of the rock volume, or 12% of the pore space. However, Vp and Vs do not always fit the model simultaneously. Vp can vary substantially more than Vs. Thus we conclude that a model, in which higher concentrations of hydrate do not affect shear stiffness, is more appropriate. Results suggest gas hydrates form within the pore space of the sediments and become part of the rock framework in our survey area.

  4. A Hydrate Database: Vital to the Technical Community

    Directory of Open Access Journals (Sweden)

    D Sloan

    2007-06-01

    Full Text Available Natural gas hydrates may contain more energy than all the combined other fossil fuels, causing hydrates to be a potentially vital aspect of both energy and climate change. This article is an overview of the motivation, history, and future of hydrate data management using a CODATA vehicle to connect international hydrate databases. The basis is an introduction to the Gas Hydrate Markup Language (GHML to connect various hydrate databases. The accompanying four articles on laboratory hydrate data by Smith et al., on field hydrate data by L?wner et al., on hydrate modeling by Wang et al., and on construction of a Chinese gas hydrate system by Xiao et al. provide details of GHML in their respective areas.

  5. Atomistic simulations of cation hydration in sodium and calcium montmorillonite nanopores

    Science.gov (United States)

    Yang, Guomin; Neretnieks, Ivars; Holmboe, Michael

    2017-08-01

    During the last four decades, numerous studies have been directed to the swelling smectite-rich clays in the context of high-level radioactive waste applications and waste-liners for contaminated sites. The swelling properties of clay mineral particles arise due to hydration of the interlayer cations and the diffuse double layers formed near the negatively charged montmorillonite (MMT) surfaces. To accurately study the cation hydration in the interlayer nanopores of MMT, solvent-solute and solvent-clay surface interactions (i.e., the solvation effects and the shape effects) on the atomic level should be taken into account, in contrast to many recent electric double layer based methodologies using continuum models. Therefore, in this research we employed fully atomistic simulations using classical molecular dynamics (MD) simulations, the software package GROMACS along with the CLAYFF forcefield and the SPC/E water model. We present the ion distributions and the deformation of the hydrated coordination structures, i.e., the hydration shells of Na+ and Ca2+ in the interlayer, respectively, for MMT in the first-layer, the second-layer, the third-layer, the fourth-layer, and the fifth-layer (1W, 2W, 3W, 4W, and 5W) hydrate states. Our MD simulations show that Na+ in Na-MMT nanopores have an affinity to the ditrigonal cavities of the clay layers and form transient inner-sphere complexes at about 3.8 Å from clay midplane at water contents less than the 5W hydration state. However, these phenomena are not observed in Ca-MMT regardless of swelling states. For Na-MMT, each Na+ is coordinated to four water molecules and one oxygen atom of the clay basal-plane in the first hydration shell at the 1W hydration state, and with five to six water molecules in the first hydration shell within a radius of 3.1 Å at all higher water contents. In Ca-MMT, however each Ca2+ is coordinated to approximately seven water molecules in the first hydration shell at the 1W hydration state and

  6. Exogenous origin of hydration on asteroid (16) Psyche: the role of hydrated asteroid families

    Science.gov (United States)

    Avdellidou, C.; Delbo', M.; Fienga, A.

    2018-04-01

    Asteroid (16) Psyche, which for a long time was the largest M-type with no detection of hydration features in its spectrum, was recently discovered to have a weak 3-μm band and thus it was eventually added to the group of hydrated asteroids. Its relatively high density, in combination with the high radar albedo, led researchers to classify the asteroid as a metallic object. It is believed that it is possibly a core of a differentiated body, a remnant of `hit-and-run' collisions. The detection of hydration is, in principle, inconsistent with a pure metallic origin for this body. Here, we consider the scenario in which the hydration on its surface is exogenous and was delivered by hydrated impactors. We show that impacting asteroids that belong to families whose members have the 3-μm band can deliver hydrated material to Psyche. We developed a collisional model with which we test all dark carbonaceous asteroid families, which contain hydrated members. We find that the major source of hydrated impactors is the family of Themis, with a total implanted mass on Psyche of the order of ˜1014 kg. However, the hydrated fraction could be only a few per cent of the implanted mass, as the water content in carbonaceous chondrite meteorites, the best analogue for the Themis asteroid family, is typically a few per cent of their mass.

  7. Oceanic hydrates: more questions than answers

    International Nuclear Information System (INIS)

    Laherrere, Jean

    2000-01-01

    Methane hydrates create problems by blocking pipelines and casing; they are also accused of contributing to environmental problems (e.g. global warming). Methane hydrates are also found in permafrost areas and in oceanic sediments where the necessary temperature and pressure for stability occur. Claims for the widespread occurrence in thick oceanic deposits are unfounded: apparently indirect evidence from seismic reflectors, seismic hydrocarbon indicators, logs and free samples is unreliable. At one time, hydrate was seen as a static, biogenic, continuous, huge resource but that view is changing to one of a dynamic, overpressurised, discontinuous and unreliable resource. Only Japan and India are currently showing any serious interest in hydrates. Academic research has raised more questions than answers. It is suggested that more hard exploratory evidence rather than theoretical study is required

  8. Vibrational dynamics of hydration water in amylose

    CERN Document Server

    Cavatorta, F; Albanese, G; Angelini, N

    2002-01-01

    We present a study of the dynamical properties of hydration water associated with amylose helices, based on low-temperature vibrational spectra collected using the TOSCA inelastic spectrometer at ISIS. The structural constraints of the polysaccharidic chains favour the formation of a high-density structure for water, which has been suggested by Imberty and Perez on the basis of conformational analysis. According to this model, hydration water can only enter the pores formed by six adjacent helices and completely fills the pores at a hydration level of about 0.27-g water/g dry amylose. Our measurements show that the dynamical behaviour of hydration water is similar to that observed in high-density amorphous ice. (orig.)

  9. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products...

  10. Hydration states of AFm cement phases

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  11. ConocoPhillips Gas Hydrate Production Test

    Energy Technology Data Exchange (ETDEWEB)

    Schoderbek, David [ConocoPhillips Co., Houston, TX (United States); Farrell, Helen [ConocoPhillips Co., Houston, TX (United States); Howard, James [ConocoPhillips Co., Houston, TX (United States); Raterman, Kevin [ConocoPhillips Co., Houston, TX (United States); Silpngarmlert, Suntichai [ConocoPhillips Co., Houston, TX (United States); Martin, Kenneth [ConocoPhillips Co., Houston, TX (United States); Smith, Bruce [ConocoPhillips Co., Houston, TX (United States); Klein, Perry [ConocoPhillips Co., Houston, TX (United States)

    2013-06-30

    Work began on the ConocoPhillips Gas Hydrates Production Test (DOE award number DE-NT0006553) on October 1, 2008. This final report summarizes the entire project from January 1, 2011 to June 30, 2013.

  12. Hydrate Control for Gas Storage Operations

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Savidge

    2008-10-31

    The overall objective of this project was to identify low cost hydrate control options to help mitigate and solve hydrate problems that occur in moderate and high pressure natural gas storage field operations. The study includes data on a number of flow configurations, fluids and control options that are common in natural gas storage field flow lines. The final phase of this work brings together data and experience from the hydrate flow test facility and multiple field and operator sources. It includes a compilation of basic information on operating conditions as well as candidate field separation options. Lastly the work is integrated with the work with the initial work to provide a comprehensive view of gas storage field hydrate control for field operations and storage field personnel.

  13. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Ali Kadaster; Bill Liddell; Tommy Thompson; Thomas Williams; Michael Niedermayr

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and implemented for determining physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. Final efforts of the project are to correlate geology, geophysics, logs, and drilling and

  14. Supramolecular Organization of Nonstoichiometric Drug Hydrates: Dapsone

    Directory of Open Access Journals (Sweden)

    Doris E. Braun

    2018-02-01

    Full Text Available The observed moisture- and temperature dependent transformations of the dapsone (4,4′-diaminodiphenyl sulfone, DDS 0. 33-hydrate were correlated to its structure and the number and strength of the water-DDS intermolecular interactions. A combination of characterization techniques was used, including thermal analysis (hot-stage microscopy, differential scanning calorimetry and thermogravimetric analysis, gravimetric moisture sorption/desorption studies and variable humidity powder X-ray diffraction, along with computational modeling (crystal structure prediction and pair-wise intermolecular energy calculations. Depending on the relative humidity the hydrate contains between 0 and 0.33 molecules of water per molecule DDS. The crystal structure is retained upon dehydration indicating that DDS hydrate shows a non-stoichiometric (dehydration behavior. Unexpectedly, the water molecules are not located in structural channels but at isolated-sites of the host framework, which is counterintuitively for a hydrate with non-stoichiometric behavior. The water-DDS interactions were estimated to be weaker than water-host interactions that are commonly observed in stoichiometric hydrates and the lattice energies of the isomorphic dehydration product (hydrate structure without water molecules and (form III differ only by ~1 kJ mol−1. The computational generation of hypothetical monohydrates confirms that the hydrate with the unusual DDS:water ratio of 3:1 is more stable than a feasible monohydrate structure. Overall, this study highlights that a deeper understanding of the formation of hydrates with non-stoichiometric behavior requires a multidisciplinary approach including suitable experimental and computational methods providing a firm basis for the development and manufacturing of high quality drug products.

  15. Preservation of methane hydrate at 1 atm

    Science.gov (United States)

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

    2001-01-01

    A "pressure-release" method that enables reproducible bulk preservation of pure, porous, methane hydrate at conditions 50 to 75 K above its equilibrium T (193 K) at 1 atm is refined. The amount of hydrate preserved by this method appears to be greatly in excess of that reported in the previous citations, and is likely the result of a mechanism different from ice shielding.

  16. Hydration and temperature interdependence of protein picosecond dynamics.

    Science.gov (United States)

    Lipps, Ferdinand; Levy, Seth; Markelz, A G

    2012-05-14

    We investigate the nature of the solvent motions giving rise to the rapid temperature dependence of protein picoseconds motions at 220 K, often referred to as the protein dynamical transition. The interdependence of picoseconds dynamics on hydration and temperature is examined using terahertz time domain spectroscopy to measure the complex permittivity in the 0.2-2.0 THz range for myoglobin. Both the real and imaginary parts of the permittivity over the frequency range measured have a strong temperature dependence at >0.27 h (g water per g protein), however the permittivity change is strongest for frequencies 1 THz, and 0.27 h for frequencies <1 THz. The data are consistent with the dynamical transition solvent fluctuations requiring only clusters of ~5 water molecules, whereas the enhancement of lowest frequency motions requires a fully spanning water network. This journal is © the Owner Societies 2012

  17. In Situ Raman Analyses of Natural Gas and Gas Hydrates at Hydrate Ridge, Oregon

    Science.gov (United States)

    Peltzer, E. T.; White, S. N.; Dunk, R. M.; Brewer, P. G.; Sherman, A. D.; Schmidt, K.; Hester, K. C.; Sloan, E. D.

    2004-12-01

    During a July 2004 cruise to Hydrate Ridge, Oregon, MBARI's sea-going laser Raman spectrometer was used to obtain in situ Raman spectra of natural gas hydrates and natural gas venting from the seafloor. This was the first in situ analysis of gas hydrates on the seafloor. The hydrate spectra were compared to laboratory analyses performed at the Center for Hydrate Research, Colorado School of Mines. The natural gas spectra were compared to MBARI gas chromatography (GC) analyses of gas samples collected at the same site. DORISS (Deep Ocean Raman In Situ Spectrometer) is a laboratory model laser Raman spectrometer from Kaiser Optical Systems, Inc modified at MBARI for deployment in the deep ocean. It has been successfully deployed to depths as great as 3600 m. Different sampling optics provide flexibility in adapting the instrument to a particular target of interest. An immersion optic was used to analyze natural gas venting from the seafloor at South Hydrate Ridge ( ˜780 m depth). An open-bottomed cube was placed over the vent to collect the gas. The immersion optic penetrated the side of the cube as did a small heater used to dissociate any hydrate formed during sample collection. To analyze solid hydrates at both South and North Hydrate Ridge ( ˜590 m depth), chunks of hydrate were excavated from the seafloor and collected in a glass cylinder with a mesh top. A stand-off optic was used to analyze the hydrate inside the cylinder. Due to the partial opacity of the hydrate and the small focal volume of the sampling optic, a precision underwater positioner (PUP) was used to focus the laser spot onto the hydrate. PUP is a stand-alone system with three degrees-of-freedom, capable of moving the DORISS probe head with a precision of 0.1 mm. In situ Raman analyses of the gas indicate that it is primarily methane. This is verified by GC analyses of samples collected from the same site. Other minor constituents (such as CO2 and higher hydrocarbons) are present but may be in

  18. Restaurant No. 1 fully renovated

    CERN Document Server

    2007-01-01

    The Restaurant No. 1 team. After several months of patience and goodwill on the part of our clients, we are delighted to announce that the major renovation work which began in September 2006 has now been completed. From 21 May 2007 we look forward to welcoming you to a completely renovated restaurant area designed with you in mind. The restaurant team wishes to thank all its clients for their patience and loyalty. Particular attention has been paid in the new design to creating a spacious serving area and providing a wider choice of dishes. The new restaurant area has been designed as an open-plan space to enable you to view all the dishes before making your selection and to move around freely from one food access point to another. It comprises user-friendly areas that fully comply with hygiene standards. From now on you will be able to pick and choose to your heart's content. We invite you to try out wok cooking or some other speciality. Or select a pizza or a plate of pasta with a choice of two sauces fr...

  19. Fully Employing Software Inspections Data

    Science.gov (United States)

    Shull, Forrest; Feldmann, Raimund L.; Seaman, Carolyn; Regardie, Myrna; Godfrey, Sally

    2009-01-01

    Software inspections provide a proven approach to quality assurance for software products of all kinds, including requirements, design, code, test plans, among others. Common to all inspections is the aim of finding and fixing defects as early as possible, and thereby providing cost savings by minimizing the amount of rework necessary later in the lifecycle. Measurement data, such as the number and type of found defects and the effort spent by the inspection team, provide not only direct feedback about the software product to the project team but are also valuable for process improvement activities. In this paper, we discuss NASA's use of software inspections and the rich set of data that has resulted. In particular, we present results from analysis of inspection data that illustrate the benefits of fully utilizing that data for process improvement at several levels. Examining such data across multiple inspections or projects allows team members to monitor and trigger cross project improvements. Such improvements may focus on the software development processes of the whole organization as well as improvements to the applied inspection process itself.

  20. The influence of Na2O on the hydration of C3A II. Suspension hydration

    NARCIS (Netherlands)

    Spierings, G.A.C.M.; Stein, H.N.

    1976-01-01

    The influence of Na2O on the hydration of C3A was studied in suspensions from the start of the reaction onwards. The heat evolution rate in very early stages of the hydration, measured at varying NaOH concentrations, and SEM, indicate that at NaOH concentrations larger then 0.1 M the reaction

  1. Distinguishing between hydrated, partially hydrated or unhydrated clinker in hardened concrete using microscopy

    NARCIS (Netherlands)

    Valcke, S.L.A.; Rooij, M.R. de; Visser, J.H.M.; Nijland, T.G.

    2010-01-01

    Hydration of clinker particles is since long a topic of interest in both designing and optimizing cement composition and its quantity used in concrete. The interest for carefully observing and also quantifying the type or stage of clinker hydration in hardened cement paste is twofold. Firstly, the

  2. Methane hydrate dissociation using inverted five-spot water flooding method in cubic hydrate simulator

    International Nuclear Information System (INIS)

    Li, Gang; Li, Xiao-Sen; Li, Bo; Wang, Yi

    2014-01-01

    The combination forms of the hydrate dissociation methods in different well systems are divided into 6 main patterns. Dissociation processes of methane hydrate in porous media using the inverted five-spot water flooding method (Pattern 4) are investigated by the experimental observation and numerical simulation. In situ methane hydrate is synthesized in the Cubic Hydrate Simulator (CHS), a 5.832-L cubic reactor. A center vertical well is used as the hot water injection well, while the four vertical wells at the corner are the gas and water production wells. The gas production begins simultaneously with the hot water injection, while after approximately 20 min of compression, the water begins to be produced. One of the common characteristics of the inverted five-spot water flooding method is that both the gas and water production rates decrease with the reduction of the hydrate dissociation rate. The evaluation of the energy efficiency ratio might indicate the inverted five-spot water flooding as a promising gas producing method from the hydrate reservoir. - Highlights: • A three-dimensional 5.8-L cubic pressure vessel is developed. • Gas production of hydrate using inverted five-spot flooding method is studied. • Water/gas production rate and energy efficiency ratio are evaluated. • Temperature distributions of numerical simulation and experiment agree well. • Hydrate dissociation process is a moving boundary problem in this study

  3. Controls on Gas Hydrate Formation and Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Miriam Kastner; Ian MacDonald

    2006-03-03

    The main objectives of the project were to monitor, characterize, and quantify in situ the rates of formation and dissociation of methane hydrates at and near the seafloor in the northern Gulf of Mexico, with a focus on the Bush Hill seafloor hydrate mound; to record the linkages between physical and chemical parameters of the deposits over the course of one year, by emphasizing the response of the hydrate mound to temperature and chemical perturbations; and to document the seafloor and water column environmental impacts of hydrate formation and dissociation. For these, monitoring the dynamics of gas hydrate formation and dissociation was required. The objectives were achieved by an integrated field and laboratory scientific study, particularly by monitoring in situ formation and dissociation of the outcropping gas hydrate mound and of the associated gas-rich sediments. In addition to monitoring with the MOSQUITOs, fluid flow rates and temperature, continuously sampling in situ pore fluids for the chemistry, and imaging the hydrate mound, pore fluids from cores, peepers and gas hydrate samples from the mound were as well sampled and analyzed for chemical and isotopic compositions. In order to determine the impact of gas hydrate dissociation and/or methane venting across the seafloor on the ocean and atmosphere, the overlying seawater was sampled and thoroughly analyzed chemically and for methane C isotope ratios. At Bush hill the pore fluid chemistry varies significantly over short distances as well as within some of the specific sites monitored for 440 days, and gas venting is primarily focused. The pore fluid chemistry in the tub-warm and mussel shell fields clearly documented active gas hydrate and authigenic carbonate formation during the monitoring period. The advecting fluid is depleted in sulfate, Ca Mg, and Sr and is rich in methane; at the main vent sites the fluid is methane supersaturated, thus bubble plumes form. The subsurface hydrology exhibits both

  4. Hydration of urea and alkylated urea derivatives

    Science.gov (United States)

    Kaatze, Udo

    2018-01-01

    Compressibility data and broadband dielectric spectra of aqueous solutions of urea and some of its alkylated derivatives have been evaluated to yield their numbers Nh of hydration water molecules per molecule of solute. Nh values in a broad range of solute concentrations are discussed and are compared to hydration numbers of other relevant molecules and organic ions. Consistent with previous results, it is found that urea differs from other solutes in its unusually small hydration number, corresponding to just one third of the estimated number of nearest neighbor molecules. This remarkable hydration behavior is explained by the large density φH of hydrogen bonding abilities offered by the urea molecule. In terms of currently discussed models of reorientational motions and allied dynamics in water and related associating liquids, the large density φH causes a relaxation time close to that of undisturbed water with most parts of water encircling the solute. Therefore only a small part of disturbed ("hydration") water is left around each urea molecule. Adding alkyl groups to the basic molecule leads to Nh values which, within the series of n-alkylurea derivatives, progressively increase with the number of methyl groups per solute. With n-butylurea, Nh from dielectric spectra, in conformity with many other organic solutes, slightly exceeds the number of nearest neighbors. Compared to such Nh values, hydration numbers from compressibility data are substantially smaller, disclosing incorrect assumptions in the formula commonly used to interpret the experimental compressibilities. Similar to other series of organic solutes, effects of isomerization have been found with alkylated urea derivatives, indicating that factors other than the predominating density φH of hydrogen bond abilities contribute also to the hydration properties.

  5. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 1 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    laboratory experiments in a radial cell. We collapse the behavior in the form of a phase diagram fully characterized by two dimensionless groups: a modified capillary number and a ?fracturing number? that reflects the balance between the pressure forces that act to open conduits in the granular pack, and frictional forces that resist it. We use all this small-scale knowledge to propose simple mechanistic models of gas migration and hydrate formation at the geologic bed scale. We propose that methane transport in lake and oceanic sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other methane-rich sediment systems, and to assess its climate feedbacks.

  6. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    laboratory experiments in a radial cell. We collapse the behavior in the form of a phase diagram fully characterized by two dimensionless groups: a modified capillary number and a ?fracturing number? that reflects the balance between the pressure forces that act to open conduits in the granular pack, and frictional forces that resist it. We use all this small-scale knowledge to propose simple mechanistic models of gas migration and hydrate formation at the geologic bed scale. We propose that methane transport in lake and oceanic sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other methane-rich sediment systems, and to assess its climate feedbacks.

  7. The fully Mobile City Government Project (MCity)

    DEFF Research Database (Denmark)

    Scholl, Hans; Fidel, Raya; Mai, Jens Erik

    2006-01-01

    The Fully Mobile City Government Project, also known as MCity, is an interdisciplinary research project on the premises, requirements, and effects of fully mobile, wirelessly connected applications (FWMC). The project will develop an analytical framework for interpreting the interaction and inter......The Fully Mobile City Government Project, also known as MCity, is an interdisciplinary research project on the premises, requirements, and effects of fully mobile, wirelessly connected applications (FWMC). The project will develop an analytical framework for interpreting the interaction...

  8. Hydrates on tap: scientists say natural gas hydrates may be tough nut to crack

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, J.

    2001-12-01

    Gas hydrates are methane molecules trapped in cages of water molecules, yielding a substance with a slushy, sherbet-like consistency. Drilling for hydrates is similar to conventional oil and gas drilling, however, the secret to economic production still remains hidden. Hydrates exist in abundance in such places as deep ocean floor and below ground in some polar regions. The real challenge lies in producing gas from this resource, inasmuch as there is no existing technology for production of gas specifically from methane hydrates. This paper describes an international research program, involving a five-country partnership to spud the first of three wells into the permafrost of the Mackenzie River Delta in the Northwest Territories. The project, worth about $15 million, has brought together public funding and expertise from Japan, Germany, India as well as the Canadian and US Geological Surveys and the US Dept. of Energy in an effort to gain information on the production response of gas hydrates. The operator of the project is Japan Petroleum Exploration Company of Canada, a subsidiary of Japan National Oil Corporation. Since Japan is poor in domestic hydrocarbon resources, but is surrounded by deep water that contains potential for gas hydrates, Japan has a great deal riding on the success of this project. Germany and the United States are also very much interested. Current thinking is that gas is in contact with the hydrates and that it should be possible to develop a free gas reservoir as if it were a conventional deposit. As the free gas is drawn off, the pressure is reduced on the hydrates in contact with it , the hydrates dissociate from the gas and replenish the conventional reservoir. So far this is still only a theory, but it appears to be a sensible approach to hydrate production. 1 photo.

  9. Experimental Determination of Refractive Index of Gas Hydrates

    DEFF Research Database (Denmark)

    Bylov, Martin; Rasmussen, Peter

    1997-01-01

    . For methane hydrate (structure I) the refractive index was found to be 1.346 and for natural gas hydrate (structure II) it was found to be 1.350. The measurements further suggest that the gas hydrate growth rate increases if the water has formed hydrates before. The induction time, on the other hand, seems......The refractive indexes of methane hydrate and natural gas hydrate have been experimentally determined. The refractive indexes were determined in an indirect manner making use of the fact that two non-absorbing materials will have the same refractive index if they cannot be distinguished visually...

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

    Science.gov (United States)

    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

  11. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  12. Experimental investigation of methane release from hydrate formation in sandstone through both hydrate dissociation and CO{sub 2} sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Husebo, J.; Graue, A.; Kvamme, B. [Bergen Univ., Bergen (Norway). Dept. of Physics and Technology; Stevens, J.; Howard, J.J. [ConocoPhillips, Ponca City, OK (United States); Baldwin, B.A. [Green Country Petrophysics LLC, Dewey, OK (United States)

    2008-07-01

    Large amounts of natural gas trapped in hydrate reservoirs are found in Arctic regions and in deep offshore locations around the world. Natural gas production from hydrate deposits offer significant potential for future energy needs. However, research is needed in order to propose potential production schemes for natural gas hydrates. Natural gas molecules can be freed from hydrate structured cages by depressurization, by heating and by exposing the hydrate to a substance that will form a thermodynamically more stable hydrate structure. This paper provided a comparison of two approaches for releasing methane from methane hydrate in porous sandstone. The study scope covered the dissociation rate of methane hydrate in porous media through depressurization, and also referred to previous work done on producing methane from hydrates in sandstone while sequestering carbon dioxide (CO{sub 2}). The study was conducted in a laboratory setting. The paper discussed the experimental design which included the placing of a pressure- and temperature-controlled sample holder inside the bore of a magnetic resonance imager. The experimental procedures were then outlined, with reference to hydrate formation; carbon dioxide sequestration; hydrate dissociation experiments with constant volume; and hydrate dissociation experiments at constant pressure. The constant volume experiments demonstrated that in order to dissociate a large amount of hydrate, the initial depressurization had to be significantly lower than the hydrate stability pressure. 9 refs., 9 figs.

  13. Strength Estimation for Hydrate-Bearing Sediments From Direct Shear Tests of Hydrate-Bearing Sand and Silt

    Science.gov (United States)

    Liu, Zhichao; Dai, Sheng; Ning, Fulong; Peng, Li; Wei, Houzhen; Wei, Changfu

    2018-01-01

    Safe and economic methane gas production, as well as the replacement of methane while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding of the strength and volume responses of hydrate-bearing sediments during shear. This study employs a custom-made apparatus to investigate the mechanical and volumetric behaviors of carbon dioxide hydrate-bearing sediments subjected to direct shear. The results show that both peak and residual strengths increase with increased hydrate saturation and vertical stress. Hydrate contributes mainly the cohesion and dilatancy constraint to the peak strength of hydrate-bearing sediments. The postpeak strength reduction is more evident and brittle in specimens with higher hydrate saturation and under lower stress. Significant strength reduction after shear failure is expected in silty sediments with high hydrate saturation Sh ≥ 0.65. Hydrate contribution to the residual strength is mainly by increasing cohesion at low hydrate saturation and friction at high hydrate saturation. Stress state and hydrate saturation are dominating both the stiffness and the strength of hydrate-bearing sediments; thus, a wave velocity-based peak strength prediction model is proposed and validated, which allows for precise estimation of the shear strength of hydrate-bearing sediments through acoustic logging data. This method is advantageous to geomechanical simulators, particularly when the experimental strength data of natural samples are not available.

  14. Clustering mechanism of oxocarboxylic acids involving hydration reaction: Implications for the atmospheric models

    Science.gov (United States)

    Liu, Ling; Kupiainen-Määttä, Oona; Zhang, Haijie; Li, Hao; Zhong, Jie; Kurtén, Theo; Vehkamäki, Hanna; Zhang, Shaowen; Zhang, Yunhong; Ge, Maofa; Zhang, Xiuhui; Li, Zesheng

    2018-06-01

    The formation of atmospheric aerosol particles from condensable gases is a dominant source of particulate matter in the boundary layer, but the mechanism is still ambiguous. During the clustering process, precursors with different reactivities can induce various chemical reactions in addition to the formation of hydrogen bonds. However, the clustering mechanism involving chemical reactions is rarely considered in most of the nucleation process models. Oxocarboxylic acids are common compositions of secondary organic aerosol, but the role of oxocarboxylic acids in secondary organic aerosol formation is still not fully understood. In this paper, glyoxylic acid, the simplest and the most abundant atmospheric oxocarboxylic acid, has been selected as a representative example of oxocarboxylic acids in order to study the clustering mechanism involving hydration reactions using density functional theory combined with the Atmospheric Clusters Dynamic Code. The hydration reaction of glyoxylic acid can occur either in the gas phase or during the clustering process. Under atmospheric conditions, the total conversion ratio of glyoxylic acid to its hydration reaction product (2,2-dihydroxyacetic acid) in both gas phase and clusters can be up to 85%, and the product can further participate in the clustering process. The differences in cluster structures and properties induced by the hydration reaction lead to significant differences in cluster formation rates and pathways at relatively low temperatures.

  15. Squirt flow due to interfacial water films in hydrate bearing sediments

    Directory of Open Access Journals (Sweden)

    K. Sell

    2018-05-01

    Full Text Available Sediments containing gas hydrate dispersed in the pore space are known to show a characteristic seismic anomaly which is a high attenuation along with increasing seismic velocities. Currently, this observation cannot be fully explained albeit squirt-flow type mechanisms on the microscale have been speculated to be the cause. Recent major findings from in situ experiments, using the gas in excess and water in excess formation method, and coupled with high-resolution synchrotron-based X-ray micro-tomography, have revealed the systematic presence of thin water films between the quartz grains and the encrusting hydrate. The data obtained from these experiments underwent an image processing procedure to quantify the thicknesses and geometries of the aforementioned interfacial water films. Overall, the water films vary from sub-micrometer to a few micrometers in thickness. In addition, some of the water films interconnect through water bridges. This geometrical analysis is used to propose a new conceptual squirt flow model for hydrate bearing sediments. A series of numerical simulations is performed considering variations of the proposed model to study seismic attenuation caused by such thin water films. Our results support previous speculation that squirt flow can explain high attenuation at seismic frequencies in hydrate bearing sediments, but based on a conceptual squirt flow model which is geometrically different than those previously considered.

  16. Hydraulic and Mechanical Effects from Gas Hydrate Conversion and Secondary Gas Hydrate Formation during Injection of CO2 into CH4-Hydrate-Bearing Sediments

    Science.gov (United States)

    Bigalke, N.; Deusner, C.; Kossel, E.; Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Abendroth, S.; Thaler, J.; Haeckel, M.

    2014-12-01

    The injection of CO2 into CH4-hydrate-bearing sediments has the potential to drive natural gas production and simultaneously sequester CO2 by hydrate conversion. The process aims at maintaining the in situ hydrate saturation and structure and causing limited impact on soil hydraulic properties and geomechanical stability. However, to increase hydrate conversion yields and rates it must potentially be assisted by thermal stimulation or depressurization. Further, secondary formation of CO2-rich hydrates from pore water and injected CO2 enhances hydrate conversion and CH4 production yields [1]. Technical stimulation and secondary hydrate formation add significant complexity to the bulk conversion process resulting in spatial and temporal effects on hydraulic and geomechanical properties that cannot be predicted by current reservoir simulation codes. In a combined experimental and numerical approach, it is our objective to elucidate both hydraulic and mechanical effects of CO2 injection and CH4-CO2-hydrate conversion in CH4-hydrate bearing soils. For the experimental approach we used various high-pressure flow-through systems equipped with different online and in situ monitoring tools (e.g. Raman microscopy, MRI and ERT). One particular focus was the design of triaxial cell experimental systems, which enable us to study sample behavior even during large deformations and particle flow. We present results from various flow-through high-pressure experimental studies on different scales, which indicate that hydraulic and geomechanical properties of hydrate-bearing sediments are drastically altered during and after injection of CO2. We discuss the results in light of the competing processes of hydrate dissociation, hydrate conversion and secondary hydrate formation. Our results will also contribute to the understanding of effects of temperature and pressure changes leading to dissociation of gas hydrates in ocean and permafrost systems. [1] Deusner C, Bigalke N, Kossel E

  17. Effect of overpressure on gas hydrate distribution

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, G.; Chapman, W.G.; Hirasaki, G.J. [Rice Univ., Houston, TX (United States). Dept. of Chemical and Biomolecular Engineering; Dickens, G.R.; Dugan, B. [Rice Univ., Houston, TX (United States). Dept. of Earth Sciences

    2008-07-01

    Natural gas hydrate systems can be characterized by high sedimentation rates and/or low permeability sediments, which can lead to pore pressure higher than hydrostatic. This paper discussed a study that examined this effect of overpressure on gas hydrate and free gas distribution in marine sediments. A one-dimensional numerical model that coupled sedimentation, fluid flow, and gas hydrate formation was utilized. In order to quantify the relative importance of sedimentation rates and low permeability sediments, a dimensionless sedimentation-compaction group (scN) was defined, that compared the absolute permeability of the sediments to the sedimentation rate. Higher values of scN mean higher permeability or low sedimentation rate which generally yield hydrostatic pore pressure while lower values of scN normally create pore pressure greater than hydrostatic. The paper discussed non-hydrostatic consolidation in gas hydrate systems, including mass balances; constitutive relationships; normalized variables; and dimensionless groups. A numerical solution to the problem was presented. It was concluded that simulation results demonstrated that decreasing scN not only increased pore pressure above hydrostatic values, but also lowered the lithostatic stress gradient and gas hydrate saturation. This occurred because overpressure resulted in lower effective stress, causing higher porosity and lower bulk density of the sediment. 16 refs., 5 figs., 1 appendix.

  18. Methane hydrates in quaternary climate change

    International Nuclear Information System (INIS)

    Kennett, J. P.; Hill, T. M.; Behl, R. J.

    2005-01-01

    The hydrate reservoir in marine sediments is known to contain a large volume of exchangeable carbon stored as solid methane hydrate and associated free gas. This reservoir has been shown to be potentially unstable in response to changing intermediate water temperature and sea level (pressure). Evidence continues to grow for past episodes of major methane release at times of climatic warming. Yet few studies of late Quaternary climate change include methane hydrates as an integral part of the global climate system, in spite of the largest known oscillations at this time in sea level and upper ocean temperature changes for the Cenozoic or earlier, conditions that favor instability of the methane hydrate reservoir. Abrupt increases in atmospheric methane recorded in polar ice cores are widely believed to have resulted, not from ocean-floor methane degassing, but instead from continental wetland activation, a hypothesis thus far unsupported by geological data. Furthermore, as part of this Wetland Methane Hypothesis, the abrupt methane increases have been seen as a response to climatic warming rather than contributing significantly to the change. An alternative view (formulated as the Clathrate Gun Hypothesis) is that the speed, magnitude and timing of abrupt climate change in the recent geologic past are consistent with the process of major degassing of methane hydrates. We summarize aspects of this hypothesis here and needs to test this hypothesis. (Author)

  19. Blue LED irradiation to hydration of skin

    Science.gov (United States)

    Menezes, Priscila F. C.; Requena, Michelle B.; Lizarelli, Rosane F., Z.; Bagnato, Vanderlei S.

    2015-06-01

    Blue LED system irradiation shows many important properties on skin as: bacterial decontamination, degradation of endogenous skin chromophores and biostimulation. In this clinical study we prove that the blue light improves the skin hydration. In the literature none authors reports this biological property on skin. Then this study aims to discuss the role of blue light in the skin hydration. Twenty patients were selected to this study with age between 25-35 years old and phototype I, II and III. A defined area from forearm was pre determined (A = 4.0 cm2). The study was randomized in two treatment groups using one blue light device (power of 5.3mW and irradiance of 10.8mW/cm2). The first treatment group was irradiated with 3J/cm2 (277seconds) and the second with 6J/cm2 (555 seconds). The skin hydration evaluations were done using a corneometer. The measurements were collected in 7, 14, 21 and 30 days, during the treatment. Statistical test of ANOVA, Tukey and T-Student were applied considering 5% of significance. In conclusion, both doses were able to improve the skin hydration; however, 6J/cm2 has kept this hydration for 30 days.

  20. Effects of Nanosilica on Early Age Stages of Cement Hydration

    Directory of Open Access Journals (Sweden)

    Forood Torabian Isfahani

    2017-01-01

    Full Text Available Effects of nanosilica on cement hydration have been broadly investigated in the literature and early age cement hydration, as a whole, has been mainly considered, disregarding the substages of the hydration. The hydration of cement is characterized by different substages and nanosilica effect on the hydration could be a result of diverse, even contradictory, behavior of nanosilica in individual stages of the hydration. In this study, effects of nanosilica on different substages of cement hydration are investigated. Isothermal calorimetry results show that at early ages (initial 72 hours the effects of nanosilica depend on the phenomenon by which the hydration is governed: when the hydration is chemically controlled, that is, during initial reaction, dormant period, and acceleratory period, the hydration rate is accelerated by adding nanosilica; when the hydration is governed by diffusion process, that is, during postacceleratory period, the hydration rate is decelerated by adding nanosilica. The Thermal Gravimetric Analysis on the samples at the hardened state (after 28 days of curing reveals that, after adding nanosilica, the hydration degree slightly increased compared to the plain paste.

  1. Morphology studies on gas hydrates interacting with silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Beltran, J.; Servio, P. [McGill Univ., Montreal, PQ (Canada). Dept. of Chemical Engineering

    2008-07-01

    Clathrate hydrates or gas hydrates are non-stoichiometric, crystalline compounds that form when small molecules come in contact with water at certain temperatures and pressures. Natural gas hydrates are found in the ocean bottom and in permafrost regions. It is thought that the amount of energy stored in natural hydrates is at least twice that of all other fossil fuels combined. In addition, trapping carbon dioxide as a hydrate in the bottom of the ocean has been suggested as an alternative means of reducing atmospheric carbon dioxide levels. Naturally occurring clathrates are found in close interaction with fine grained particles of very small mean pore diameters. Even though an increasing amount of hydrate equilibrium data for small diameter porous media has become available, the morphological behavior of hydrates subject to such conditions is yet to be explored. This paper presented a study that visually examined hydrate formation and decomposition of gas hydrates while interacting with fine grains of silica gel. The study showed still frames from high-resolution video recordings for hydrate formation and decomposition. The paper discussed the experiment including the apparatus as well as the results of hydrate formation and hydrate dissociation. This study enabled for the first time to observe clathrate morphology while hydrates interacted closely with fine grain particles with small mean pore diameters. 9 refs., 8 figs.

  2. Methane hydrates in nature - Current knowledge and challenges

    Science.gov (United States)

    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

  3. Thermodynamic of hydration of a Wyoming montmorillonite saturated with Ca, Mg, Na and K

    International Nuclear Information System (INIS)

    Vieillard, P.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Giffaut, E.

    2010-01-01

    Document available in extended abstract form only. In the context of a disposal within clayey formations (Callovo-Oxfordian argillite) or using clayey barriers, the assessment of the long-term behavior of clay materials by geochemical modeling, requires thermodynamic properties of clay minerals. The Thermochimie database has been created by ANDRA in 1996 in order to provide coherent thermodynamic data of many minerals of interests with regards to this context, such as clay minerals. However, the thermodynamic properties of clay minerals, which govern the stability of these minerals in solution are still poorly understood. Indeed, there is little experimental data available in the literature concerning the hydration of smectites. On the other hand, it is not possible to acquire all the experimental thermodynamic hydration properties of clay minerals involved in natural systems or likely to be in the implementation of a deep disposal. In this study, we propose a method to estimate the thermodynamic hydration properties of a clay mineral. By considering the following reaction: Smectite nm H 2 O Smectite (0 H 2 O) + nm H 2 O (l), the hydration of smectite is calculated from an equilibrium condition involving anhydrous and hydrous components in which nm is the maximal number of moles of water in the fully hydrated end-member. By using a solid-solution formalism, the variation of the hydration state of a smectite with temperature or [H 2 O] can be possible. Analysis of experimental data indicates that solid solutions of hydrous and anhydrous smectite components at 25 deg. C and 1 bar are not ideal but can be expressed in terms of regular solution theory by considering the excess molal enthalpy of mixing (Hxs), the excess molal entropy of mixing (Sxs) and excess molal Gibbs free energy of mixing (Gxs) for binary solid solutions of homologous hydrous and anhydrous smectite components expressed in terms of Margules parameters W1 and W2. A compilation of measurements of

  4. Fuel cell membrane hydration and fluid metering

    Science.gov (United States)

    Jones, Daniel O.; Walsh, Michael M.

    1999-01-01

    A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel in order to mix its respective portion of liquid water with the corresponding portion of the stream. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

  5. Hydration dynamics of hyaluronan and dextran.

    Science.gov (United States)

    Hunger, Johannes; Bernecker, Anja; Bakker, Huib J; Bonn, Mischa; Richter, Ralf P

    2012-07-03

    Hyaluronan is a polysaccharide, which is ubiquitous in vertebrates and has been reported to be strongly hydrated in a biological environment. We study the hydration of hyaluronan in solution using the rotational dynamics of water as a probe. We measure these dynamics with polarization-resolved femtosecond-infrared and terahertz time-domain spectroscopies. Both experiments reveal that a subensemble of water molecules is slowed down in aqueous solutions of hyaluronan amounting to ∼15 water molecules per disaccharide unit. This quantity is consistent with what would be expected for the first hydration shell. Comparison of these results to the water dynamics in aqueous dextran solution, a structurally similar polysaccharide, yields remarkably similar results. This suggests that the observed interaction with water is a common feature for hydrophilic polysaccharides and is not specific to hyaluronan. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Multicavity SCRF calculation of ion hydration energies

    International Nuclear Information System (INIS)

    Diercksen, B.H.F.; Karelson, M.; Tamm, T.

    1994-01-01

    The hydration energies of the proton, hydroxyl ion, and several inorganic ions were calculated using the multicavity self-consistent reaction field (MCa SCRF) method developed for the quantum-mechanical modeling of rotationally or flexible systems in dielectric media. The ionic complexes H 3 O + (H2O) 4 , OH - (H2O) 4 , NH + 4 (H2O) 4 , and Hal - (H2O) 4 , where Hal = F, Cl, or Br, have been studied. Each complex was divided between five spheres, corresponding to the central ion and four water molecules in their first coordination sphere, respectively. Each cavity was surrounded by a polarizable medium with the dielectric permittivity of water at room temperature (80). The ionic hydration energies of ions were divided into specific and nonspecific parts. After accounting for the cavity-formation energy using scaled particle theory, good agreement between the total calculated and experimental hydration energies was obtained for all ions studied

  7. Thermal expansion properties of calcium aluminate hydrates

    International Nuclear Information System (INIS)

    Song, Tae Woong

    1986-01-01

    In order to eliminate the effect of impurities and aggregates on the thermomechanical properties of the various calcium aluminate hydrates, and to prepare clinkers in which all calcium aluminates are mixed homogeneously, chemically pure CaO and Al 2 O 3 were weighed, blended and heated in various conditions. After quantitative X-ray diffractometry(QXRD), the synthesized clinker was hydrated and cured under the conditions of 30 deg C, W/C=0.5, relative humidity> 90% respectively during 24 hours. And then differential thermal analysis(DTA), thermogravimetry(TG), micro calorimetry, thermomechanical analysis(TMA) and scanning electron microanalysis(SEM) were applied to examine the thermal properties of samples containing, calcium aluminate hydrates in various quantity. (Author)

  8. THz characterization of hydrated and anhydrous materials

    Science.gov (United States)

    Sokolnikov, Andre

    2011-06-01

    The characterization of anhydrous and hydrated forms of materials is of great importance to science and industry. Water content poses difficulties for successful identification of the material structure by THz radiation. However, biological tissues and hydrated forms of nonorganic substances still may be investigated by THz radiation. This paper outlines the range of possibilities of the above characterization, as well as provides analysis of the physical mechanism that allows or prevents penetration of THz waves through the substance. THz-TDS is used to measure the parameters of the characterization of anhydrous and hydrated forms of organic and nonorganic samples. Mathematical methods (such as prediction models of time-series analysis) are used to help identifying the absorption coefficient and other parameters of interest. The discovered dependencies allow designing techniques for material identification/characterization (e.g. of drugs, explosives, etc. that may have water content). The results are provided.

  9. Relaxation mechanism of the hydrated electron.

    Science.gov (United States)

    Elkins, Madeline H; Williams, Holly L; Shreve, Alexander T; Neumark, Daniel M

    2013-12-20

    The relaxation dynamics of the photoexcited hydrated electron have been subject to conflicting interpretations. Here, we report time-resolved photoelectron spectra of hydrated electrons in a liquid microjet with the aim of clarifying ambiguities from previous experiments. A sequence of three ultrashort laser pulses (~100 femtosecond duration) successively created hydrated electrons by charge-transfer-to-solvent excitation of dissolved anions, electronically excited these electrons via the s→p transition, and then ejected them into vacuum. Two distinct transient signals were observed. One was assigned to the initially excited p-state with a lifetime of ~75 femtoseconds, and the other, with a lifetime of ~400 femtoseconds, was attributed to s-state electrons just after internal conversion in a nonequilibrated solvent environment. These assignments support the nonadiabatic relaxation model.

  10. Ground movements associated with gas hydrate production

    International Nuclear Information System (INIS)

    Siriwardane, H.J.; Kutuk, B.

    1992-03-01

    This report deals with a study directed towards a modeling effort on production related ground movements and subsidence resulting from hydrate dissociation. The goal of this research study was to evaluate whether there could be subsidence related problems that could be an impediment to hydrate production. During the production of gas from a hydrate reservoir, it is expected that porous reservoir matrix becomes more compressible which may cause reservoir compression (compaction) under the influence of overburden weight. The overburden deformations can propagate its influence upwards causing subsidence near the surface where production equipment will be located. In the present study, the reservoir compaction is modeled by using the conventional ''stress equilibrium'' approach. In this approach, the overburden strata move under the influence of body force (i.e. self weight) in response to the ''cavity'' generated by reservoir depletion. The present study is expected to provide a ''lower bound'' solution to the subsidence caused by hydrate reservoir depletion. The reservoir compaction anticipated during hydrate production was modeled by using the finite element method, which is a powerful computer modeling technique. The ground movements at the reservoir roof (i.e. reservoir compression) cause additional stresses and disturbance in the overburden strata. In this study, the reservoir compaction was modeled by using the conventional ''stress equilibrium'' approach. In this approach, the overburden strata move under the influence of body force (i.e. self weight) in response to the ''cavity'' generated by reservoir depletion. The resulting stresses and ground movements were computed by using the finite element method. Based on the parameters used in this investigation, the maximum ground subsidence could vary anywhere from 0.50 to 6.50 inches depending on the overburden depth and the size of the depleted hydrate reservoir

  11. Irrigation port hydration in phacoemulsification surgery

    Directory of Open Access Journals (Sweden)

    Suzuki H

    2018-01-01

    Full Text Available Hisaharu Suzuki,1 Yoichiro Masuda,2 Yuki Hamajima,1 Hiroshi Takahashi3 1Department of Ophthalmology, Nippon Medical School Musashikosugi Hospital, Kawasaki City, Kanagawa, 2Department of Ophthalmology, The Jikei University, Katsushika Medical Center, Tokyo, 3Department of Ophthalmology, Nippon Medical School, Tokyo, Japan Background: In most cases, hydration is performed by water injection into the stromal tissue with a needle. The technique is simple, however it is sometimes troublesome.Purpose: We describe a simple technique for hydrating the corneal stroma in cataract surgery using an irrigation port.Patients and methods: The technique began by pushing the irrigation port against the corneal stroma for a few seconds during phacoemulsification, which generated edema in the corneal incision that subsequently prevented leakage. This procedure is called the hydration using irrigation port (HYUIP technique. A total of 60 eyes were randomized and placed in two groups, 30 eyes underwent surgeries using the HYUIP technique (HYUIP group and 30 eyes underwent surgeries without the HYUIP technique (control. The three points evaluated during each surgery included 1 the occurrence of anterior chamber collapse during the pulling out of the I/A tip after inserting the intraocular lens, 2 the need for conventional hydration, and 3 watertight completion at the end stage of surgery.Results: The anterior chamber collapse and the need for conventional hydration were significantly smaller in the HYUIP group compared to the control group. Regarding the self-sealing completion, no significant difference was observed between the two groups.Conclusion: The HYUIP technique is an effective method for creating self-sealing wound. In addition, this technique helps to prevent anterior chamber collapse. Keywords: cataract surgery, hydration, irrigation and aspiration, phacoemulsification, wound, self-sealing 

  12. Hydration and nutrition knowledge in adolescent swimmers. Does water intake affect urine hydration markers after swimming?

    Directory of Open Access Journals (Sweden)

    Cesare Altavilla

    2017-12-01

    Full Text Available Little data exists regarding nutritional knowledge and hydration in adolescent swimmers. The aim of this study was to assess the level of nutrition and hydration knowledge and to describe the fluid balance in adolescent swimmers during training. A study was carried out with a cross-sectional descriptive part and a longitudinal part with repeated measurements over five swimming sessions. Eighty-six adolescent swimmers completed a questionnaire to assess their sport nutrition and hydration knowledge. Fluid balance and urine hydration markers were studied during training. Swimmers showed a limited nutrition knowledge (33.26 % ± SD 12.59 and meagre hydration knowledge (28.61 % ± SD 28.59. Females showed lower scores than male swimmers in nutrition and hydration knowledge. Based on urine specific gravity, swimmers started the training close to the euhydrated threshold (1.019 g/mL ± SD 0.008. Although urine specific gravity and urine colour were reduced after the training, there were minimal changes in body mass (-0.12 Kg ± SD 0.31. Sweat loss (2.67 g/min ± SD 3.23 and the net changes in the fluid balance (-0.22 % ± SD 0.59 were low. The poor knowledge in nutrition and hydration encountered in the swimmers can justify the development of a strategy to incorporate nutritional education programmes for this group. Body water deficit from swimming activity seems to be easily replaced with the water intake to maintain hydration. After the training, the urine of swimmers was diluted regardless of their water intake. Dilution of urine did not reflect real hydration state in swimming.

  13. Risk factors of methane hydrate resource development in the concentrated zones distributed in the eastern Nankai Trough

    Science.gov (United States)

    Yamamoto, K.; Nagakubo, S.

    2009-04-01

    Some environmental and safety concerns on the offshore methane hydrate development have been raised, but the ground of such allegations are sometime not fully reasonable. The risks of methane hydrate resource development to environment and safety should be discussed upon methane hydrate occurrences condition, the production methods, and the designs of production system, under comprehensively scientific manners. In the Phase 1 of the Methane Hydrate Exploitation Program in Japan (FY2001-2008), the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) found methane hydrate concentrated zones in the eastern Nankai Trough that are potential prospects for resource development. The concentrated zones are consisted of turbidite-derived sandy sediments and hydrate crystals in pore spaces of sand grains (pore-filling type structure). The MH21 Research Consortium proposed the depressurization method as prime technique due to its efficiency of gas production in such concentrated zones, and has tried to develop conceptual designs of production systems based on the information of existing devices and facilities. Under the condition and circumstances described above, the authors tried to extract and evaluate some risk factors concerning methane hydrate development using depressurization in the area. Leakage of methane gas, that is less harmful substance to ecosystem than heavier hydrocarbons, from production system can be one possible risk. However, in the case of gas production through wellbore, even if catastrophic damages happen in the subsea production system during gas production, the leakages do not continue because the borehole could be filled by seawater and depressurization is stopped immediately. Another possible risk is a leakage of produced gas through seafloor. If methane hydrate production makes high pressure or temperature zones in sediments, the risk should be considered. However, depressurization method makes opposite condition

  14. Thermal decomposition of uranyl sulphate hydrate

    International Nuclear Information System (INIS)

    Sato, T.; Ozawa, F.; Ikoma, S.

    1980-01-01

    The thermal decomposition of uranyl sulphate hydrate (UO 2 SO 4 .3H 2 O) has been investigated by thermogravimetry, differential thermal analysis, X-ray diffraction and infrared spectrophotometry. As a result, it is concluded that uranyl sulphate hydrate decomposes thermally: UO 2 SO 4 .3H 2 O → UO 2 SO 4 .xH 2 O(2.5 = 2 SO 4 . 2H 2 O → UO 2 SO 4 .H 2 O → UO 2 SO 4 → α-UO 2 SO 4 → β-UO 2 SO 4 → U 3 O 8 . (author)

  15. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.; Chae, S. R.; Benmore, C. J.; Wenk, H. R.; Monteiro, P. J. M.

    2010-01-01

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  16. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  17. Spectral Decomposition and Other Seismic Attributes for Gas Hydrate Prospecting

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, Dan

    2018-02-25

    Studying the sediments at the base of gas hydrate stability is ideal for determining the seismic response to gas hydrate saturation. First, assuming gas migration to the shallow section, this area is more likely to have concentrated gas hydrate because it encompasses the zone in which upward moving buoyant gas transitions to form immobile gas hydrate deposits. Second, this zone is interesting because these areas have the potential to show a hydrate filled zone and a gas filled zone within the same sediments. Third, the fundamental measurement within seismic data is impedance contrasts between velocity*density layers. High saturation gas hydrates and free gas inhabit opposite ends of these measurements making the study of this zone ideal for investigating the seismic characteristics of gas hydrate and, hence, the investigation of other seismic attributes that may indicate gas hydrate fill.

  18. The rates measurement of methane hydrate formation and dissociation using micro-drilling system application for gas hydrate exploration

    Energy Technology Data Exchange (ETDEWEB)

    Bin Dou [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)]|[Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Reinicke, K.M. [Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Guosheng Jiang; Xiang Wu; Fulong Ning [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)

    2006-07-01

    When drilling through gas hydrate bearing formations, the energy supplied by virtue of the drilling process may lead to a destabilization of the hydrates surrounding the wellbore. Therefore, as the number of oil and gas fields being development in deepwater and onshore arctic environments increases, greater emphasis should be placed on quantifying the risks, gas hydrates pose to drilling operations. The qualification of these risks requires a comprehensive understanding of gas hydrate-formation and dissociation as a result of drilling induced processes. To develop the required understanding of gas hydrat formation and dissociation, the authors conducted laboratory experiments by using a micro-drilling system, to study the dissociation rates of methane hydrates contained in a tank reactor. The test facility used is a development of China University of Geosciences. The rates of methane hydrate formation and dissociation in the tank reactor were measured at steady-state conditions at pressures ranging from 0.1 to 25 MPa and temperatures ranging from -5 to 20 C. The experimental results show that the rate of hydrate formation is strongly influenced by the fluid system used to form the hydrates, pressure and temperature, with the influence of the temperature on methane hydrate dissociation being stronger than that of the pressure. Drilling speed, drilling fluids and hydrate dissociation inhibitors were also shown to influence hydrate dissociation rate. The derived results have been used to predict hydrate drilling stability for several drilling fluid systems.

  19. Gas-hydrate concentration estimated from P- and S-wave velocities at the Mallik 2L-38 research well, Mackenzie Delta, Canada

    Science.gov (United States)

    Carcione, José M.; Gei, Davide

    2004-05-01

    We estimate the concentration of gas hydrate at the Mallik 2L-38 research site using P- and S-wave velocities obtained from well logging and vertical seismic profiles (VSP). The theoretical velocities are obtained from a generalization of Gassmann's modulus to three phases (rock frame, gas hydrate and fluid). The dry-rock moduli are estimated from the log profiles, in sections where the rock is assumed to be fully saturated with water. We obtain hydrate concentrations up to 75%, average values of 37% and 21% from the VSP P- and S-wave velocities, respectively, and 60% and 57% from the sonic-log P- and S-wave velocities, respectively. The above averages are similar to estimations obtained from hydrate dissociation modeling and Archie methods. The estimations based on the P-wave velocities are more reliable than those based on the S-wave velocities.

  20. Marine Gas Hydrates - An Untapped Non-conventional Energy ...

    Indian Academy of Sciences (India)

    Table of contents. Marine Gas Hydrates - An Untapped Non-conventional Energy Resource · Slide 2 · Slide 3 · Slide 4 · Gas Hydrate Stability Zone · Slide 6 · Slide 7 · Exploration of gas hydrates (seismic) · Characteristics of BSR · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Distribution of Gas Hydrates in KG ...

  1. Hydrate bearing clayey sediments: Formation and gas production concepts

    KAUST Repository

    Jang, Jaewon; Santamarina, Carlos

    2016-01-01

    Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

  2. Standardization and software infrastructure for gas hydrate data communications

    Energy Technology Data Exchange (ETDEWEB)

    Kroenlein, K.; Chirico, R.D.; Kazakov, A.; Frenkel, M. [National Inst. of Standards and Technology, Boulder, CO (United States). Physical and Chemical Properties Div.; Lowner, R. [GeoForschungsZentrum Potsdam (Germany); Wang, W. [Chinese Academy of Science, Beijing (China). Computer Network Information Center; Smith, T. [MIT Systems, Flushing, NY (United States); Sloan, E.D. [Colorado School of Mines, Golden, CO (United States). Centre for Hydrate Research

    2008-07-01

    The perceived value of gas hydrates as an energy resource for the future has led to extensive hydrate research studies and experiments. The hydrate deposits are widely dispersed throughout the world, and many countries are now investigating methods of extracting gas hydrate resources. This paper described a gas hydrates markup language (GHML) developed as an international standard for data transfer and storage within the gas hydrates community. The language is related to a hydrates database developed to facilitate a greater understanding of naturally occurring hydrate interactions with geophysical processes, and aid in the development of hydrate technologies for resource recovery and storage. Recent updates to the GHML included the addition of ThermoML, a communication standard for thermodynamic data into the GHML schema. The standard will be used to represent all gas hydrates thermodynamic data. A new element for the description of crystal structures has also been developed, as well as a guided data capture tool. The tool is available free of charge and is publicly licensed for use by gas hydrate data producers. A web service has also been provided to ensure that access to GHML files for gas hydrates and data files are available for users. It was concluded that the tool will help to ensure data quality assurance for the conversion of data and meta-data within the database. 28 refs., 9 figs.

  3. Small angle X-ray scattering from hydrating tricalcium silicate

    International Nuclear Information System (INIS)

    Vollet, D.

    1983-01-01

    The small-angle X-ray scattering technique was used to study the structural evolution of hydrated tricalcium silicate at room temperature. The changes in specific area of the associated porosity and the evolution of density fluctuations in the solid hydrated phase were deduced from the scattering data. A correlation of these variations with the hydration mechanism is tried. (Author) [pt

  4. Hydrate bearing clayey sediments: Formation and gas production concepts

    KAUST Repository

    Jang, Jaewon

    2016-06-20

    Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

  5. Computation of Hydration Free Energies Using the Multiple Environment Single System Quantum Mechanical/Molecular Mechanical Method.

    Science.gov (United States)

    König, Gerhard; Mei, Ye; Pickard, Frank C; Simmonett, Andrew C; Miller, Benjamin T; Herbert, John M; Woodcock, H Lee; Brooks, Bernard R; Shao, Yihan

    2016-01-12

    A recently developed MESS-E-QM/MM method (multiple-environment single-system quantum mechanical molecular/mechanical calculations with a Roothaan-step extrapolation) is applied to the computation of hydration free energies for the blind SAMPL4 test set and for 12 small molecules. First, free energy simulations are performed with a classical molecular mechanics force field using fixed-geometry solute molecules and explicit TIP3P solvent, and then the non-Boltzmann-Bennett method is employed to compute the QM/MM correction (QM/MM-NBB) to the molecular mechanical hydration free energies. For the SAMPL4 set, MESS-E-QM/MM-NBB corrections to the hydration free energy can be obtained 2 or 3 orders of magnitude faster than fully converged QM/MM-NBB corrections, and, on average, the hydration free energies predicted with MESS-E-QM/MM-NBB fall within 0.10-0.20 kcal/mol of full-converged QM/MM-NBB results. Out of five density functionals (BLYP, B3LYP, PBE0, M06-2X, and ωB97X-D), the BLYP functional is found to be most compatible with the TIP3P solvent model and yields the most accurate hydration free energies against experimental values for solute molecules included in this study.

  6. Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.

    Science.gov (United States)

    Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

    2012-01-01

    We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level.

  7. Dynamic impact indentation of hydrated biological tissues and tissue surrogate gels

    Science.gov (United States)

    Ilke Kalcioglu, Z.; Qu, Meng; Strawhecker, Kenneth E.; Shazly, Tarek; Edelman, Elazer; VanLandingham, Mark R.; Smith, James F.; Van Vliet, Krystyn J.

    2011-03-01

    For both materials engineering research and applied biomedicine, a growing need exists to quantify mechanical behaviour of tissues under defined hydration and loading conditions. In particular, characterisation under dynamic contact-loading conditions can enable quantitative predictions of deformation due to high rate 'impact' events typical of industrial accidents and ballistic insults. The impact indentation responses were examined of both hydrated tissues and candidate tissue surrogate materials. The goals of this work were to determine the mechanical response of fully hydrated soft tissues under defined dynamic loading conditions, and to identify design principles by which synthetic, air-stable polymers could mimic those responses. Soft tissues from two organs (liver and heart), a commercially available tissue surrogate gel (Perma-Gel™) and three styrenic block copolymer gels were investigated. Impact indentation enabled quantification of resistance to penetration and energy dissipative constants under the rates and energy densities of interest for tissue surrogate applications. These analyses indicated that the energy dissipation capacity under dynamic impact increased with increasing diblock concentration in the styrenic gels. Under the impact rates employed (2 mm/s to 20 mm/s, corresponding to approximate strain energy densities from 0.4 kJ/m3 to 20 kJ/m3), the energy dissipation capacities of fully hydrated soft tissues were ultimately well matched by a 50/50 triblock/diblock composition that is stable in ambient environments. More generally, the methodologies detailed here facilitate further optimisation of impact energy dissipation capacity of polymer-based tissue surrogate materials, either in air or in fluids.

  8. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  9. Gas hydrate resource quantification in Uruguay

    International Nuclear Information System (INIS)

    Tomasini, J.; De Santa Ana, H.; Veroslavsky, G.

    2012-01-01

    The gas hydrates are crystalline solids formed by natural gas (mostly methane) and water, which are stable in thermobaric conditions given under high pressures and low temperatures. These conditions are given in permafrost zones and continental margin basins offshore in the nature

  10. Pentagonal dodecahedron methane hydrate cage and methanol ...

    Indian Academy of Sciences (India)

    methane hydrate in sea bed near continental margin and underneath of permafrost ... clathrate structure,6,7 IR spectroscopy analysis of vibra- tional form of guest .... Hydrogen (H71) of the hydroxyl group of methanol is found to have formed ...

  11. A new approach to model mixed hydrates

    Czech Academy of Sciences Publication Activity Database

    Hielscher, S.; Vinš, Václav; Jäger, A.; Hrubý, Jan; Breitkopf, C.; Span, R.

    2018-01-01

    Roč. 459, March (2018), s. 170-185 ISSN 0378-3812 R&D Projects: GA ČR(CZ) GA17-08218S Institutional support: RVO:61388998 Keywords : gas hydrate * mixture * modeling Subject RIV: BJ - Thermodynamics Impact factor: 2.473, year: 2016 https://www.sciencedirect.com/science/article/pii/S0378381217304983

  12. [Terminal phase hydration, pain and delirium

    DEFF Research Database (Denmark)

    Heick, A.

    2009-01-01

    Hydration of the terminal patient may relieve confusion and complaints of "dry mouth". But it may worsen oedema of the brain, lungs, and extremities, worsen terminal rattling and cause a need for frequent changing of diapers. The decision of whether and how to treat a dying patient with fluids...

  13. Hydration dynamics near a model protein surface

    International Nuclear Information System (INIS)

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

    2003-01-01

    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

  14. A positron annihilation study of hydrated DNA

    DEFF Research Database (Denmark)

    Warman, J. M.; Eldrup, Morten Mostgaard

    1986-01-01

    Positron annihilation measurements are reported for hydrated DNA as a function of water content and as a function of temperature (20 to -180.degree. C) for samples containing 10 and 50% wt of water. The ortho-positronium mean lifetime and its intensity show distinct variations with the degree...

  15. Gold(III)-Catalyzed Hydration of Phenylacetylene

    Science.gov (United States)

    Leslie, J. Michelle; Tzeel, Benjamin A.

    2016-01-01

    A guided inquiry-based experiment exploring the regioselectivity of the hydration of phenylacetylene is described. The experiment uses an acidic gold(III) catalyst in a benign methanol/water solvent system to introduce students to alkyne chemistry and key principles of green chemistry. The experiment can be easily completed in approximately 2 h,…

  16. [Terminal phase hydration, pain and delirium

    DEFF Research Database (Denmark)

    Heick, A.

    2009-01-01

    Hydration of the terminal patient may relieve confusion and complaints of "dry mouth". But it may worsen oedema of the brain, lungs, and extremities, worsen terminal rattling and cause a need for frequent changing of diapers. The decision of whether and how to treat a dying patient with fluids sh...

  17. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, Wei; Brouwers, Jos

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  18. Clathrate Hydrates for Thermal Energy Storage in Buildings: Overview of Proper Hydrate-Forming Compounds

    Directory of Open Access Journals (Sweden)

    Beatrice Castellani

    2014-09-01

    Full Text Available Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs. The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parameter that makes a PCM suitable to be used in buildings is, first of all, a melting temperature at about 25 °C. The paper provides an overview of groups of clathrate hydrates, whose physical and chemical characteristics could meet the requirements needed for their application in buildings. Simulations with a dynamic building simulation tool are carried out to evaluate the performance of clathrate hydrates in enhancing thermal comfort through the moderation of summer temperature swings and, therefore, in reducing energy consumption. Simulations suggest that clathrate hydrates have a potential in terms of improvement of indoor thermal comfort and a reduction of energy consumption for cooling. Cooling effects of 0.5 °C and reduced overheating hours of up to 1.1% are predicted.

  19. Enthalpy of dissociation and hydration number of methane hydrate from the Clapeyron equation

    International Nuclear Information System (INIS)

    Anderson, Graydon K.

    2004-01-01

    The enthalpies of the reactions in which methane hydrate is dissociated to methane vapor and either (1) water, or (2) ice are determined by a new analysis using the Clapeyron equation. The difference in enthalpies of the two reactions is used to infer the hydration number at the quadruple point where hydrate, ice, liquid water, and methane vapor coexist. By appropriate corrections, the hydration number at points removed from the quadruple point is also determined. The most important feature of the new analysis is the direct use of the Clapeyron equation. The method avoids the use of certain simplifying assumptions that have compromised the accuracy of previous analyses in which the Clausius-Clapeyron equation was used. The analysis takes into account the finite volumes of all phases, the non-ideality of the vapor phase, and the solubility of methane in water. The results show that the enthalpy of dissociation and hydration number are constant within experimental error over the entire (hydrate, liquid, vapor) coexistence region. The results are more accurate than but entirely consistent with almost all previous studies

  20. Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

    Science.gov (United States)

    Circone, S.; Kirby, S.H.; Stern, L.A.

    2005-01-01

    The composition of methane hydrate, namely nW for CH 4??nWH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nW may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of n W = 5.81-6.10 H2O describes the entire range of measured values, with an average composition of CH4??5.99(??0.07) H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence. ?? 2005 American Chemical Society.

  1. MORPHOLOGY OF METHANE HYDRATE HOST SEDIMENTS

    International Nuclear Information System (INIS)

    JONES, K.W.; FENG, H.; TOMOV, S.; WINTER, W.J.; EATON, M.; MAHAJAN, D.

    2004-01-01

    Results from simulated experiments in several laboratories show that host sediments influence hydrate formation in accord with known heterogeneity of host sediments at sites of gas hydrate occurrence (1). For example, in Mackenzie Delta, NWT Canada (Mallik 2L-38 well), coarser-grained units (pore-filling model) are found whereas in the Gulf of Mexico, the found hydrate samples do not appear to be lithologically controlled. We have initiated a systematic study of sediments, initially focusing on samples from various depths at a specific site, to establish a correlation with hydrate occurrence (or variations thereof) to establish differences in their microstructure, porosity, and other associated properties. The synchrotron computed microtomography (CMT) set-up at the X-27A tomography beam line at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory was used as a tool to study sediments from Blake Ridge at three sub bottom depths of 0.2, 50, and 667 meters. Results from the tomographic analysis of the deepest sample (667 m) are presented here to illustrate how tomography can be used to obtain new insights into the structures of methane hydrate host sediments. The investigation shows the internal grain/pore space resolution in the microstructure and a 3-D visualization of the connecting pathways obtained following data segmentation into pore space and grains within the sediment sample. The analysis gives the sample porosity, specific surface area, mean particle size, and tortuosity, as well. An earlier report on the experimental program has been given by Mahajan et al. (2)

  2. The structure of hydrate bearing fine grained marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Priest, J.; Kingston, E.; Clayton, C. [Southampton Univ., Highfield (United Kingdom). School of Civil Engineering and the Environment; Schultheiss, P.; Druce, M. [Geotek Ltd., Daventry (United Kingdom)

    2008-07-01

    This paper discussed the structure of naturally occurring methane gas hydrates in fine-grained sediments from core samples recovered using in situ pressures from the eastern margin of the Indian Ocean. High resolution X-ray computed tomography (CT) images were taken of gas hydrate cores. The hydrate structure was examined and comparisons were made between low resolution X-ray images obtained on the cores prior to sub-sectioning and depressurization procedures. The X-ray images showed the presence of high-angle, sub-parallel veins within the recovered sediments. The scans indicated that the hydrates occurred as fracture filing veins throughout the core. Fracture orientation was predominantly sub-vertical. Thick millimetric hydrate veins were composed of sub-millimetric veins with variations in fracture angle. The analysis indicated that hydrate formation was episodic in nature and subject to changes in the stress regime. Results of the study showed that depressurization and subsequent freezing alter the structure of the sediment even when the gas hydrate has not been altered. A large proportion of the hydrate survived when outside of its stability region. The self-preserving behaviour of the hydrate was attributed to the endothermic nature of gas hydrate dissociation. It was concluded that the accurate physical characterization of gas hydrates can only be conducted when the core section remains under in situ stress conditions. 13 refs., 9 figs.

  3. Carbon dioxide hydrate formation in a fixed-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fan, S.; Lang, X. [South China Univ. of Technology, Guangzhou (China). Key Laboratory of Enhanced Heat Transfer and Energy Conservation; Wang, Y.; Liang, D. [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Energy Conversion and Guangzhou Center of Natural Gas Hydrate; Sun, X.; Jurcik, B. [Air Liquide Laboratories, Tsukuba (Japan)

    2008-07-01

    Gas hydrates are thermodynamically stable at high pressures and near the freezing temperature of pure water. Methane hydrates occur naturally in sediments in the deep oceans and permafrost regions and constitute an extensive hydrocarbon reservoir. Carbon dioxide (CO{sub 2}) hydrates are of interest as a medium for marine sequestration of anthropogenic carbon dioxide. Sequestering CO{sub 2} as hydrate has potential advantages over most methods proposed for marine CO{sub 2} sequestration. Because this technique requires a shallower depth of injection when compared with other ocean sequestration methods, the costs of CO{sub 2} hydrate sequestration may be lower. Many studies have successfully used different continuous reactor designs to produce CO{sub 2} hydrates in both laboratory and field settings. This paper discussed a study that involved the design and construction of a fixed-bed reactor for simulation of hydrate formation system. Water, river sands and carbon dioxide were used to simulate the seep kind of hydrate formation. Carbon dioxide gas was distributed as small bubbles to enter from the bottom of the fixed-bed reactor. The paper discussed the experimental data and presented a diagram of the gas hydrate reactor system. The morphology as well as the reaction characters of CO{sub 2} hydrate was presented in detail. The results were discussed in terms of experimental phenomena and hydrate formation rate. A mathematical model was proposed for describing the process. 17 refs., 7 figs.

  4. Indian National Gas Hydrate Program Expedition 01 report

    Science.gov (United States)

    Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.V.; ,

    2015-01-01

    Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years.

  5. Natural gas hydrates. Experimental techniques and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Yuguang; Liu, Changling (eds.) [Qingdao Institute of Marine Geology (China). Gas Hydrate Laboratory

    2013-07-01

    Focuses on gas hydrate experiment in laboratory. Intends to provide practical significant parameters for gas hydrate exploration and exploitation in the oceanic and permafrost environments. Consists of different themes that present up-to-date information on hydrate experiments. ''Natural Gas Hydrates: Experimental Techniques and Their Applications'' attempts to broadly integrate the most recent knowledge in the fields of hydrate experimental techniques in the laboratory. The book examines various experimental techniques in order to provide useful parameters for gas hydrate exploration and exploitation. It provides experimental techniques for gas hydrates, including the detection techniques, the thermo-physical properties, permeability and mechanical properties, geochemical abnormalities, stability and dissociation kinetics, exploitation conditions, as well as modern measurement technologies etc.

  6. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has...... a characteristic broad absorption peak at 0.5 THz corresponding to the dipole moment of THF molecules. The refractive indices of THF and propane hydrates are 1.725 and 1.775 at 1 THz, respectively, and show a slight but clear difference from the refractive index of ice (1.79). THz-TDS is a potentially useful...... technique for the ondestructive inspection of gas hydrates. # 2009 The Japan Society of Applied Physics...

  7. Comparative Assessment of Advanced Gay Hydrate Production Methods

    Energy Technology Data Exchange (ETDEWEB)

    M. D. White; B. P. McGrail; S. K. Wurstner

    2009-06-30

    Displacing natural gas and petroleum with carbon dioxide is a proven technology for producing conventional geologic hydrocarbon reservoirs, and producing additional yields from abandoned or partially produced petroleum reservoirs. Extending this concept to natural gas hydrate production offers the potential to enhance gas hydrate recovery with concomitant permanent geologic sequestration. Numerical simulation was used to assess a suite of carbon dioxide injection techniques for producing gas hydrates from a variety of geologic deposit types. Secondary hydrate formation was found to inhibit contact of the injected CO{sub 2} regardless of injectate phase state, thus diminishing the exchange rate due to pore clogging and hydrate zone bypass of the injected fluids. Additional work is needed to develop methods of artificially introducing high-permeability pathways in gas hydrate zones if injection of CO{sub 2} in either gas, liquid, or micro-emulsion form is to be more effective in enhancing gas hydrate production rates.

  8. Characterization of un-hydrated and hydrated BioAggregate™ and MTA Angelus™.

    Science.gov (United States)

    Camilleri, J; Sorrentino, F; Damidot, D

    2015-04-01

    BioAggregate™ is a novel material introduced for use as a root-end filling material. It is tricalcium silicate-based, free of aluminium and uses tantalum oxide as radiopacifier. BioAggregate contains additives to enhance the material performance. The purpose of this research was to characterize the un-hydrated and hydrated forms of BioAggregate using a combination of techniques, verify whether the additives if present affect the properties of the set material and compare these properties to those of MTA Angelus™. Un-hydrated and hydrated BioAggregate and MTA Angelus were assessed. Un-hydrated cement was tested for chemical composition, specific surface area, mineralogy and kinetics of hydration. The set material was investigated for mineralogy, microstructure and bioactivity. Scanning electron microscopy, X-ray energy dispersive spectroscopic analysis, X-ray fluorescence spectroscopy, X-ray diffraction and isothermal calorimetry were employed. The specific surface area was investigated using a gas adsorption method with nitrogen as the probe. BioAggregate was composed of tricalcium silicate, tantalum oxide, calcium phosphate and silicon dioxide and was free of aluminium. On hydration, the tricalcium silicate produced calcium silicate hydrate and calcium hydroxide. The former was deposited around the cement grains, while the latter reacted with the silicon dioxide to form additional calcium silicate hydrate. This resulted in reduction of calcium hydroxide in the aged cement. MTA Angelus reacted in a similar fashion; however, since it contained no additives, the calcium hydroxide was still present in the aged cement. Bioactivity was demonstrated by deposition of hydroxyapatite. BioAggregate exhibited a high specific surface area. Nevertheless, the reactivity determined by isothermal calorimetry appeared to be slow compared to MTA Angelus. The tantalum oxide as opposed to bismuth oxide was inert, and tantalum was not leached in solution. BioAggregate exhibited

  9. In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Lee, M.W.; Collett, T.S.

    2011-01-01

    In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

  10. LABORATORY STRATEGIES FOR HYDRATE FORMATION IN FINE-GRAINED SEDIMENTS

    KAUST Repository

    Lei, L.; Santamarina, Carlos

    2018-01-01

    Fine‐grained sediments limit hydrate nucleation, shift the phase boundary and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain‐scale gas‐storage within porous diatoms, ice‐to‐hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long‐term guest molecule transport. Tomographic images, thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine‐grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo‐pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice‐to‐hydrate transformation goes through a liquid stage at pre‐melt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time‐dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine‐grained sediments within the relatively short time‐scale available for laboratory experiments.

  11. Modeling dissociation behaviour of methane hydrate in porous soil media

    Energy Technology Data Exchange (ETDEWEB)

    Jayasinghe, A.G.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Gas hydrates, or clathrates, exist in the form of crystalline solid structures of hydrogen bonded water molecules where the lattice cages are occupied by guest gas molecules. Methane gas hydrates are the most common. As such, hydrate bearing sediments are considered to be a potential future energy resource. Gas hydrates also function as a source or sink for atmospheric methane, which may influence global warming. The authors emphasized that an understanding of the behaviour of soils containing gas hydrates is necessary in order to develop ways of recovering the vast gas resources that exist in the form of hydrates, particularly since hydrates are also suspected to be a potential factor in the initiation and propagation of submarine slope failures. Gas hydrate dissociation occurs when water and gas are released, resulting in an increase in pore fluid pressure, thereby causing significant reductions in effective stress leading to sediment failure. Dissociation may occur as a result of pressure reductions or increases in temperature. This study focused on the strength and deformation behaviour of hydrate bearing soils associated with temperature induced dissociation. Modeling the dissociation behavior of hydrates in porous soil media involves an understanding of the geomechanics of hydrate dissociation. This paper addressed the issue of coupling the hydrate dissociation problem with the soil deformation problem. A mathematical framework was constructed in which the thermally stimulated hydrate dissociation process in porous soil media under undrained conditions was considered with conduction heat transfer. It was concluded that a knowledge of geomechanical response of hydrate bearing sediments will enable better estimates of benefits and risks associated with the recovery process, thereby ensuring safe and economical exploration. 20 refs., 1 fig., 1 appendix.

  12. LABORATORY STRATEGIES FOR HYDRATE FORMATION IN FINE-GRAINED SEDIMENTS

    KAUST Repository

    Lei, L.

    2018-04-02

    Fine‐grained sediments limit hydrate nucleation, shift the phase boundary and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain‐scale gas‐storage within porous diatoms, ice‐to‐hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long‐term guest molecule transport. Tomographic images, thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine‐grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo‐pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice‐to‐hydrate transformation goes through a liquid stage at pre‐melt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time‐dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine‐grained sediments within the relatively short time‐scale available for laboratory experiments.

  13. FY1995 molecular control technology for mining of methane-gas-hydrate; 1995 nendo methane hydrate no bunshi seigyo mining

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The objectives of the investigation are as follows: 1) developing a method to control formation/dissociation of methane-gas-hydrate, 2) developing a technology to displace methane gas by CO{sub 2} in methane-gas-hydrate deposit, 3) developing a technology to produce methane gas from the deposit efficiently. The final purpose of the project is to create new mining industry that solves both the problems of energy and global environment. 1) Clustering of water molecules is found to play the key role in the methane gas hydrate formation. 2) Equilibrium properties and kinetics of gas hydrates formation and dissociation in bulk-scale gas-hydrate are clarified in the practical environmental conditions. 3) Particle size of hydrate deposit influences the formation and dissociation of bulk-scale gas-hydrate crystal. 4) Mass transfer between gas and liquid phase in turbulent bubbly flow is a function of bubble diameter. The mass transfer depends on interfacial dynamics. (NEDO)

  14. Spatial resolution of gas hydrate and permeability changes from ERT data in LARS simulating the Mallik gas hydrate production test

    Science.gov (United States)

    Priegnitz, Mike; Thaler, Jan; Spangenberg, Erik; Schicks, Judith M.; Abendroth, Sven

    2014-05-01

    The German gas hydrate project SUGAR studies innovative methods and approaches to be applied in the production of methane from hydrate-bearing reservoirs. To enable laboratory studies in pilot scale, a large reservoir simulator (LARS) was realized allowing for the formation and dissociation of gas hydrates under simulated in-situ conditions. LARS is equipped with a series of sensors. This includes a cylindrical electrical resistance tomography (ERT) array composed of 25 electrode rings featuring 15 electrodes each. The high-resolution ERT array is used to monitor the spatial distribution of the electrical resistivity during hydrate formation and dissociation experiments over time. As the present phases of poorly conducting sediment, well conducting pore fluid, non-conducting hydrates, and isolating free gas cover a wide range of electrical properties, ERT measurements enable us to monitor the spatial distribution of these phases during the experiments. In order to investigate the hydrate dissociation and the resulting fluid flow, we simulated a hydrate production test in LARS that was based on the Mallik gas hydrate production test (see abstract Heeschen et al., this volume). At first, a hydrate phase was produced from methane saturated saline water. During the two months of gas hydrate production we measured the electrical properties within the sediment sample every four hours. These data were used to establish a routine estimating both the local degrees of hydrate saturation and the resulting local permeabilities in the sediment's pore space from the measured resistivity data. The final gas hydrate saturation filled 89.5% of the total pore space. During hydrate dissociation, ERT data do not allow for a quantitative determination of free gas and remaining gas hydrates since both phases are electrically isolating. However, changes are resolved in the spatial distribution of the conducting liquid and the isolating phase with gas being the only mobile isolating phase

  15. Obsidian hydration dating of volcanic events

    Science.gov (United States)

    Friedman, I.; Obradovich, J.

    1981-01-01

    Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

  16. Experimental techniques for cement hydration studies

    Directory of Open Access Journals (Sweden)

    Andreas Luttge

    2011-10-01

    Full Text Available Cement hydration kinetics is a complex problem of dissolution, nucleation and growth that is still not well understood, particularly in a quantitative way. While cement systems are unique in certain aspects they are also comparable to natural mineral systems. Therefore, geochemistry and particularly the study of mineral dissolution and growth may be able to provide insight and methods that can be utilized in cement hydration research. Here, we review mainly what is not known or what is currently used and applied in a problematic way. Examples are the typical Avrami approach, the application of Transition State Theory (TST to overall reaction kinetics and the problem of reactive surface area. Finally, we suggest an integrated approach that combines vertical scanning interferometry (VSI with other sophisticated analytical techniques such as atomic force microscopy (AFM and theoretical model calculations based on a stochastic treatment.

  17. Limitation of biocompatibility of hydrated nanocrystalline hydroxyapatite

    Science.gov (United States)

    Minaychev, V. V.; Teleshev, A. T.; Gorshenev, V. N.; Yakovleva, M. A.; Fomichev, V. A.; Pankratov, A. S.; Menshikh, K. A.; Fadeev, R. S.; Fadeeva, I. S.; Senotov, A. S.; Kobyakova, M. I.; Yurasova, Yu B.; Akatov, V. S.

    2018-04-01

    Nanostructured hydroxyapatite (HA) in the form of hydrated paste is considered to be a promising material for a minor-invasive surgical curing of bone tissue injure. However questions about adhesion of cells on this material and its biocompatibility still remain. In this study biocompatibility of paste-formed nanosized HA (nano-HA) by in vitro methods is investigated. Nano-HA (particles sized about 20 nm) was synthesized under conditions of mechano-acoustic activation of an aqueous reaction mixture of ammonium hydrophosphate and calcium nitrate. It was ascertained that nanocrystalline paste was not cytotoxic although limitation of adhesion, spreading and growth of the cells on its surface was revealed. The results obtained point on the need of modification of hydrated nano-HA in the aims of increasing its biocompatibility and osteoplastic potential.

  18. Predicting hydration energies for multivalent ions

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Stipp, Susan Louise Svane

    2014-01-01

    We have predicted the free energy of hydration for 40 monovalent and multivalent cations and anions using density functional theory and the implicit solvent model COnductor like Screening MOdel for Real Solvents (COSMO-RS) at the Becke-Perdew (BP)/Triple zeta valence with polarization functions...... (TZVP) level. Agreement with experimental data for monovalent and divalent ions is good and shows no significant systematic errors. Predictions are noticeably better than with standard COSMO. The agreement with experimental data for trivalent and tetravalent ions is slightly worse and shows systematic...... errors. Our results indicate that quantum chemical calculations combined with COSMO-RS solvent treatment is a reliable method for treating multivalent ions in solution, provided one hydration shell of explicit water molecules is included for metal cations. The accuracy is not high enough to allow...

  19. Advances in understanding hydration of Portland cement

    International Nuclear Information System (INIS)

    Scrivener, Karen L.; Juilland, Patrick; Monteiro, Paulo J.M.

    2015-01-01

    Progress in understanding hydration is summarized. Evidence supports the geochemistry dissolution theory as an explanation for the induction period, in preference to the inhibiting layer theory. The growth of C–S–H is the principal factor controlling the main heat evolution peak. Electron microscopy indicates that C–S–H “needles” grow from the surface of grains. At the peak, the surface is covered, but deceleration cannot be attributed to diffusion control. The shoulder peak comes from renewed reaction of C 3 A after depletion of sulfate in solution, but release of sulfate absorbed on C–S–H means that ettringite continues to form. After several days space becomes the major factor controlling hydration. The use of new analytical technique is improving our knowledge of the action of superplasticizers and leading to the design of molecules for different applications. Atomistic modeling is becoming a topic of increasing interest. Recent publications in this area are reviewed

  20. Advances in understanding hydration of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Scrivener, Karen L., E-mail: Karen.scrivener@epfl.ch [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 (Switzerland); Juilland, Patrick [Sika Technology AG, Zürich (Switzerland); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California at Berkeley (United States)

    2015-12-15

    Progress in understanding hydration is summarized. Evidence supports the geochemistry dissolution theory as an explanation for the induction period, in preference to the inhibiting layer theory. The growth of C–S–H is the principal factor controlling the main heat evolution peak. Electron microscopy indicates that C–S–H “needles” grow from the surface of grains. At the peak, the surface is covered, but deceleration cannot be attributed to diffusion control. The shoulder peak comes from renewed reaction of C{sub 3}A after depletion of sulfate in solution, but release of sulfate absorbed on C–S–H means that ettringite continues to form. After several days space becomes the major factor controlling hydration. The use of new analytical technique is improving our knowledge of the action of superplasticizers and leading to the design of molecules for different applications. Atomistic modeling is becoming a topic of increasing interest. Recent publications in this area are reviewed.

  1. Modelling porewater chemistry in hydrated Portland cement

    International Nuclear Information System (INIS)

    Berner, U.R.

    1987-01-01

    Extensive employment of concrete is foreseen in radioactive waste repositories. A prerequisite for modelling the interactions between concrete and formation waters is characterization of the concrete system. Available experimental data from high pressure squeezing of cement pore-water indicate that, besides the high pH due to alkali hydroxide dissolution, cement composition itself influences the solubility determining solid phases. A model which simulates the hydration of Portland cement assuming complete hydration of the main clinker minerals is presented. The model also includes parameters describing the reactions between the cement and blending agents. Comparison with measured pore-water data generally gives a consistent picture and, as expected, the model gives correct predictions for pure Portland cements. For blended cements, the required additional parameters can, to some extent, be derived from pore-water analysis. 14 references, 1 figure, 4 tables

  2. Propane hydrate nucleation: Experimental investigation and correlation

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

    2008-01-01

    supersaturation region. The experiments showed that the gas dissolution rate rather than the induction time of propane hydrate is influenced by a change in agitation. This was especially valid at high stirring rates when the water surface was severely disturbed.Addition of polyvinylpyrrolidone (PVP......) to the aqueous phase was found to reduce the gas dissolution rate slightly. However the induction times were prolonged quite substantially upon addition of PVP.The induction time data were correlated using a newly developed induction time model based on crystallization theory also capable of taking into account...... the presence of additives. In most cases reasonable agreement between the data and the model could be obtained. The results revealed that especially the effective surface energy between propane hydrate and water is likely to change when the stirring rate varies from very high to low. The prolongation...

  3. Non-invasive measurement of corneal hydration.

    Science.gov (United States)

    March, W F; Bauer, N J

    2001-01-01

    To investigate the feasibility of a confocal Raman spectroscopic technique for the noncontact assessment of corneal hydration in vivo in two legally blind subjects. A laser beam (632.8 nm; 15 mJ) was maintained on the cornea using a microscope objective lens (25x magnification, NA=0.5, f=10 mm) both for focusing the incident light as well as collecting the Raman backscattered light, in a 180 degrees backscatter configuration. An optical fiber, acting as the confocal pinhole for elimination of light from out-of-focus places, was coupled to a spectrometer that dispersed the collected light onto a sensitive array-detector for rapid spectral data acquisition over a range from 2,890 to 3,590 cm(-1). Raman spectra were recorded from the anterior 100 to 150 microm of the cornea over a period of time before and after topical application of a mild dehydrating solution. The ratio between the amplitudes of the signals at 3,400 cm(-1) (OH-vibrational mode of water) and 2,940 cm(-1) (CH-vibrational mode of proteins) was used as a measure of corneal hydration. High signal-to-noise ratio (SNR 25) Raman spectra were obtained from the human corneas using 15 mJ of laser light energy. Qualitative changes in the hydration of the anterior-most part of the corneas could be observed as a result of the dehydrating agent. Confocal Raman spectroscopy could potentially be applied clinically as a noncontact tool for the assessment of corneal hydration in vivo.

  4. Hydration benefits to courtship feeding in crickets

    OpenAIRE

    Ivy, T. M.; Johnson, J. C.; Sakaluk, S. K.

    1999-01-01

    The spermatophore transferred by male decorated crickets (Gryllodes sigillatus) at mating includes a large gelatinous spermatophylax that the female consumes after copulation. Although previous studies have shown that G. sigillatus females gain no nutritional benefits from consuming food gifts, there may be other benefits to their consumption. We examined potential hydration benefits to females by experimentally manipulating both the availability of water and the number of food gifts that fem...

  5. Unraveling halide hydration: A high dilution approach.

    Science.gov (United States)

    Migliorati, Valentina; Sessa, Francesco; Aquilanti, Giuliana; D'Angelo, Paola

    2014-07-28

    The hydration properties of halide aqua ions have been investigated combining classical Molecular Dynamics (MD) with Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Three halide-water interaction potentials recently developed [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)], along with three plausible choices for the value of the absolute hydration free energy of the proton (ΔG [minus sign in circle symbol]hyd[H+]), have been checked for their capability to properly describe the structural properties of halide aqueous solutions, by comparing the MD structural results with EXAFS experimental data. A very good agreement between theory and experiment has been obtained with one parameter set, namely LE, thus strengthening preliminary evidences for a ΔG [minus sign in circle symbol]hyd[H] value of -1100 kJ mol(-1) [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)]. The Cl(-), Br(-), and I(-) ions have been found to form an unstructured and disordered first hydration shell in aqueous solution, with a broad distribution of instantaneous coordination numbers. Conversely, the F(-) ion shows more ordered and defined first solvation shell, with only two statistically relevant coordination geometries (six and sevenfold complexes). Our thorough investigation on the effect of halide ions on the microscopic structure of water highlights that the perturbation induced by the Cl(-), Br(-), and I(-) ions does not extend beyond the ion first hydration shell, and the structure of water in the F(-) second shell is also substantially unaffected by the ion.

  6. Reservoir Models for Gas Hydrate Numerical Simulation

    Science.gov (United States)

    Boswell, R.

    2016-12-01

    Scientific and industrial drilling programs have now providing detailed information on gas hydrate systems that will increasingly be the subject of field experiments. The need to carefully plan these programs requires reliable prediction of reservoir response to hydrate dissociation. Currently, a major emphasis in gas hydrate modeling is the integration of thermodynamic/hydrologic phenomena with geomechanical response for both reservoir and bounding strata. However, also critical to the ultimate success of these efforts is the appropriate development of input geologic models, including several emerging issues, including (1) reservoir heterogeneity, (2) understanding of the initial petrophysical characteristics of the system (reservoirs and seals), the dynamic evolution of those characteristics during active dissociation, and the interdependency of petrophysical parameters and (3) the nature of reservoir boundaries. Heterogeneity is ubiquitous aspect of every natural reservoir, and appropriate characterization is vital. However, heterogeneity is not random. Vertical variation can be evaluated with core and well log data; however, core data often are challenged by incomplete recovery. Well logs also provide interpretation challenges, particularly where reservoirs are thinly-bedded due to limitation in vertical resolution. This imprecision will extend to any petrophysical measurements that are derived from evaluation of log data. Extrapolation of log data laterally is also complex, and should be supported by geologic mapping. Key petrophysical parameters include porosity, permeability and it many aspects, and water saturation. Field data collected to date suggest that the degree of hydrate saturation is strongly controlled by/dependant upon reservoir quality and that the ratio of free to bound water in the remaining pore space is likely also controlled by reservoir quality. Further, those parameters will also evolve during dissociation, and not necessary in a simple

  7. The combined effect of thermodynamic promoters tetrahydrofuran and cyclopentane on the kinetics of flue gas hydrate formation

    DEFF Research Database (Denmark)

    Daraboina, Nagu; von Solms, Nicolas

    2015-01-01

    ) hydrate formation using a rocking cell apparatus. Hydrate formation and decomposition kinetics were investigated by constant cooling (hydrate nucleation temperature) and isothermal (hydrate nucleation time) methods. Improved (synergistic) hydrate formation kinetics (hydrate nucleation and growth) were...... of these two promoters is favorable both thermodynamically and kinetically for hydrate formation from flue gas....

  8. Experimental solid state NMR of gas hydrates : problems and solutions

    Energy Technology Data Exchange (ETDEWEB)

    Moudrakovski, I.; Lu, H.; Ripmeester, J. [National Research Council of Canada, Ottawa, ON (Canada). Steacie Inst. for Molecular Sciences; Kumar, R.; Susilo, R. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Luzi, M. [GeoForschungsZentrum Potsdam, Potsdam (Germany)

    2008-07-01

    Solid State NMR is a suitable spectroscopic technique for hydrate research for several reasons, including its capability to distinguish between different structural types of hydrates, its quantitative nature and potential for both in-situ and time resolved experiments. This study illustrated the applications of solid state NMR for compositional and structural studies of clathrate hydrates, with particular emphasis on experimental techniques and potential ways to overcome technical difficulties. In order to use the method to its full capacity, some instrumental developments are needed to adapt it to the specific experimental requirements of hydrate studies, such as very low temperatures and high pressures. This presentation discussed the quantification of the Carbon-13 spectra with examples from natural and synthetic hydrates prepared from multi-component mixtures of hydrocarbons. The main approach used for the first two examples was Carbon-13 NMR with Magic Angle Spinning (MAS) at -100 degrees C. The detailed characterization of mixed hydrogen hydrates required low temperature hydrogen MAS. The quantification problems encountered during these experiments were also discussed. The purpose of these recent experimental developments was to prompt wider application of Solid State NMR in hydrate research. NMR proved to be a viable method for analyzing the composition and structure of multi-component mixed gas hydrates; characterizing natural gas hydrates; and, evaluating the formation conditions and properties of mixed hydrogen hydrates. The limitations of the method were highlighted and sensible choices of experimental conditions and techniques that ensure accurate results were discussed. 34 refs., 10 figs.

  9. Effect of Gemini-type surfactant on methane hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

    2008-07-01

    Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

  10. Carbon dioxide gas hydrates accumulation in freezing and frozen sediments

    Energy Technology Data Exchange (ETDEWEB)

    Chuvilin, E.; Guryeva, O. [Moscow State Univ., Moscow (Russian Federation). Dept. of Geology

    2008-07-01

    Carbon dioxide (CO{sub 2}) hydrates and methane hydrates can be formed, and exist under natural conditions. The permafrost area has been considered as an environment for the potential disposal of CO{sub 2}. The favorable factors for preserving CO{sub 2} in liquid and gas hydrate states in frozen sediments and under permafrost horizons are great thickness of frozen sediments; low permeability in comparison with thawed sediments; and favourable conditions for hydrates formation. Therefore, research on the formation and existence conditions of CO{sub 2} gas hydrates in permafrost and under permafrost sediments are of great importance for estimation of CO{sub 2} disposal conditions in permafrost, and for working out specific sequestration schemes. This paper presented the results of an experimental study on the process of carbon dioxide (CO{sub 2}) gas hydrates formation in the porous media of sediments under positive and negative temperatures. Sediment samples of various compositions including those selected in the permafrost area were used. The research was conducted in a special pressure chamber, which allowed to monitor pressure and temperature. The study used the monitoring results in order to make quantitative estimation of the kinetics of CO{sub 2} hydrates accumulation in the model sediments. Results were presented in terms of kinetics of CO{sub 2} hydrates accumulation in the porous media at positive and negative temperatures; kinetics of CO{sub 2} hydrates accumulation in various porous media; gas hydrate-former influence on kinetics of hydrates accumulation in frozen sediments; and influence of freezing on CO{sub 2} hydrates accumulation in porous media. It was concluded that hydrate accumulation took an active place in porous media not only under positive, but also under high negative temperatures, when the water was mainly in the form of ice in porous media. 27 refs., 3 tabs., 5 figs.

  11. Polymorphism in Br2 clathrate hydrates.

    Science.gov (United States)

    Goldschleger, I U; Kerenskaya, G; Janda, K C; Apkarian, V A

    2008-02-07

    The structure and composition of bromine clathrate hydrate has been controversial for more than 170 years due to the large variation of its observed stoichiometries. Several different crystal structures were proposed before 1997 when Udachin et al. (Udachin, K. A.; Enright, G. D.; Ratcliffe, C. I.; Ripmeester, J. A. J. Am. Chem. Soc. 1997, 119, 11481) concluded that Br2 forms only the tetragonal structure (TS-I). We show polymorphism in Br2 clathrate hydrates by identifying two distinct crystal structures through optical microscopy and resonant Raman spectroscopy on single crystals. After growing TS-I crystals from a liquid bromine-water solution, upon dropping the temperature slightly below -7 degrees C, new crystals of cubic morphology form. The new crystals, which have a limited thermal stability range, are assigned to the CS-II structure. The two structures are clearly distinguished by the resonant Raman spectra of the enclathrated Br2, which show long overtone progressions and allow the extraction of accurate vibrational parameters: omega(e) = 321.2 +/- 0.1 cm(-1) and omega(e)x(e) = 0.82 +/- 0.05 cm(-1) in TS-I and omega(e) = 317.5 +/- 0.1 cm(-1) and omega(e)x(e) = 0.70 +/- 0.1 cm(-1) in CS-II. On the basis of structural analysis, the discovery of the CS-II crystals implies stability of a large class of bromine hydrate structures and, therefore, polymorphism.

  12. The economics of exploiting gas hydrates

    International Nuclear Information System (INIS)

    Döpke, Lena-Katharina; Requate, Till

    2014-01-01

    We investigate the optimal exploitation of methane hydrates, a recent discovery of methane resources under the sea floor, mainly located along the continental margins. Combustion of methane (releasing CO2) and leakage through blow-outs (releasing CH4) contribute to the accumulation of greenhouse gases. A second externality arises since removing solid gas hydrates from the sea bottom destabilizes continental margins and thus increases the risk of marine earthquakes. We show that in such a model three regimes can occur: i) resource exploitation will be stopped in finite time, and some of the resource will stay in situ, ii) the resource will be used up completely in finite time, and iii) the resource will be exhausted in infinite time. We also show how to internalize the externalities by policy instruments. - Highlights: • We set up a model of optimal has hydrate exploitation • We incorporate to types of damages: contribution to global warming and geo-hazards • We characterize optimal exploitation paths and study decentralization with an exploitation tax. • Three regimes can occur: • i) exploitation in finite time and some of the stock remaining in situ, • ii) exploitation in finite time and the resource will be exhausted, • iii) exploitation and exhaustion in infinite time

  13. Raman spectroscopic studies of hydrogen clathrate hydrates.

    Science.gov (United States)

    Strobel, Timothy A; Sloan, E Dendy; Koh, Carolyn A

    2009-01-07

    Raman spectroscopic measurements of simple hydrogen and tetrahydrofuran+hydrogen sII clathrate hydrates have been performed. Both the roton and vibron bands illuminate interesting quantum dynamics of enclathrated H(2) molecules. The complex vibron region of the Raman spectrum has been interpreted by observing the change in population of these bands with temperature, measuring the absolute H(2) content as a function of pressure, and with D(2) isotopic substitution. Quadruple occupancy of the large sII clathrate cavity shows the highest H(2) vibrational frequency, followed by triple and double occupancies. Singly occupied small cavities display the lowest vibrational frequency. The vibrational frequencies of H(2) within all cavity environments are redshifted from the free gas phase value. At 76 K, the progression from ortho- to para-H(2) occurs over a relatively slow time period (days). The rotational degeneracy of H(2) molecules within the clathrate cavities is lifted, observed directly in splitting of the para-H(2) roton band. Raman spectra from H(2) and D(2) hydrates suggest that the occupancy patterns between the two hydrates are analogous, increasing confidence that D(2) is a suitable substitute for H(2). The measurements suggest that Raman is an effective and convenient method to determine the relative occupancy of hydrogen molecules in different clathrate cavities.

  14. Electronic structure calculations of calcium silicate hydrates

    International Nuclear Information System (INIS)

    Sterne, P.A.; Meike, A.

    1995-11-01

    Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO 3 ) and xonotlite (Ca 6 Si 6 O 17 (OH) 2 ), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases

  15. Intermolecular Hydrogen Transfer in Isobutane Hydrate

    Directory of Open Access Journals (Sweden)

    Takeshi Sugahara

    2012-05-01

    Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

  16. Impact of Compound Hydrate Dynamics on Phase Boundary Changes

    Science.gov (United States)

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

    2006-12-01

    Compound hydrate reactions are affected by the local concentration of hydrate forming materials (HFM). The relationship between HFM composition and the phase boundary is as significant as temperature and pressure. Selective uptake and sequestration of preferred hydrate formers (PF) has wide ranging implications for the state and potential use of natural hydrate formation, including impact on climate. Rising mineralizing fluids of hydrate formers (such as those that occur on Earth and are postulated to exist elsewhere in the solar system) will sequester PF before methane, resulting in a positive relationship between depth and BTU content as ethane and propane are removed before methane. In industrial settings the role of preferred formers can separate gases. When depressurizing gas hydrate to release the stored gas, the hydrate initial composition will set the decomposition phase boundary because the supporting solution takes on the composition of the hydrate phase. In other settings where hydrate is formed, transported, and then dissociated, similar effects can control the process. The behavior of compound hydrate systems can primarily fit into three categories: 1) In classically closed systems, all the material that can form hydrate is isolated, such as in a sealed laboratory vessel. In such systems, formation and decomposition are reversible processes with observed hysteresis related to mass or heat transfer limitations, or the order and magnitude in which individual hydrate forming gases are taken up from the mixture and subsequently released. 2) Kinetically closed systems are exposed to a solution mass flow across a hydrate mass. These systems can have multiple P-T phase boundaries based on the local conditions at each face of the hydrate mass. A portion of hydrate that is exposed to fresh mineralizing solution will contain more preferred hydrate formers than another portion that is exposed to a partially depleted solution. Examples of kinetically closed

  17. Protein Hydration Thermodynamics: The Influence of Flexibility and Salt on Hydrophobin II Hydration.

    Science.gov (United States)

    Remsing, Richard C; Xi, Erte; Patel, Amish J

    2018-04-05

    The solubility of proteins and other macromolecular solutes plays an important role in numerous biological, chemical, and medicinal processes. An important determinant of protein solubility is the solvation free energy of the protein, which quantifies the overall strength of the interactions between the protein and the aqueous solution that surrounds it. Here we present an all-atom explicit-solvent computational framework for the rapid estimation of protein solvation free energies. Using this framework, we estimate the hydration free energy of hydrophobin II, an amphiphilic fungal protein, in a computationally efficient manner. We further explore how the protein hydration free energy is influenced by enhancing flexibility and by the addition of sodium chloride, and find that it increases in both cases, making protein hydration less favorable.

  18. Stabilization of ammonia-rich hydrate inside icy planets.

    Science.gov (United States)

    Naden Robinson, Victor; Wang, Yanchao; Ma, Yanming; Hermann, Andreas

    2017-08-22

    The interior structure of the giant ice planets Uranus and Neptune, but also of newly discovered exoplanets, is loosely constrained, because limited observational data can be satisfied with various interior models. Although it is known that their mantles comprise large amounts of water, ammonia, and methane ices, it is unclear how these organize themselves within the planets-as homogeneous mixtures, with continuous concentration gradients, or as well-separated layers of specific composition. While individual ices have been studied in great detail under pressure, the properties of their mixtures are much less explored. We show here, using first-principles calculations, that the 2:1 ammonia hydrate, (H 2 O)(NH 3 ) 2 , is stabilized at icy planet mantle conditions due to a remarkable structural evolution. Above 65 GPa, we predict it will transform from a hydrogen-bonded molecular solid into a fully ionic phase O 2- ([Formula: see text]) 2 , where all water molecules are completely deprotonated, an unexpected bonding phenomenon not seen before. Ammonia hemihydrate is stable in a sequence of ionic phases up to 500 GPa, pressures found deep within Neptune-like planets, and thus at higher pressures than any other ammonia-water mixture. This suggests it precipitates out of any ammonia-water mixture at sufficiently high pressures and thus forms an important component of icy planets.

  19. Focus on the Development of Natural Gas Hydrate in China

    Directory of Open Access Journals (Sweden)

    Zhongfu Tan

    2016-05-01

    Full Text Available Natural gas hydrate, also known as combustible ice, and mainly composed of methane, is identified as a potential clean energy for the 21st century. Due to its large reserves, gas hydrate can ease problems caused by energy resource shortage and has gained attention around the world. In this paper, we focus on the exploration and development of gas hydrate as well as discussing its status and future development trend in China and abroad. We then analyze its opportunities and challenges in China from four aspects, resource, technology, economy and policy, with five forces model and Politics Economics Society Technology method. The results show China has abundance gas hydrate resource; however, backward technologies and inadequate investment have seriously hindered the future development of gas hydrate; thus, China should establish relevant cooperation framework and intuitional arrangement to attract more investment as well as breaking through technical difficulties to commercialization gas hydrate as soon as possible.

  20. Raman studies of methane-ethane hydrate metastability.

    Science.gov (United States)

    Ohno, Hiroshi; Strobel, Timothy A; Dec, Steven F; Sloan, E Dendy; Koh, Carolyn A

    2009-03-05

    The interconversion of methane-ethane hydrate from metastable to stable structures was studied using Raman spectroscopy. sI and sII hydrates were synthesized from methane-ethane gas mixtures of 65% or 93% methane in ethane and water, both with and without the kinetic hydrate inhibitor, poly(N-vinylcaprolactam). The observed faster structural conversion rate in the higher methane concentration atmosphere can be explained in terms of the differences in driving force (difference in chemical potential of water in sI and sII hydrates) and kinetics (mass transfer of gas and water rearrangement). The kinetic hydrate inhibitor increased the conversion rate at 65% methane in ethane (sI is thermodynamically stable) but retards the rate at 93% methane in ethane (sII is thermodynamically stable), implying there is a complex interaction between the polymer, water, and hydrate guests at crystal surfaces.

  1. Enzyme hydration, activity and flexibility : A neutron scattering approach

    International Nuclear Information System (INIS)

    Kurkal-Siebert, V.; Finney, J.L.; Daniel, R.M.; Smith, Jeremy C.

    2006-01-01

    Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. The question of whether the hydration-induced enzyme flexibility is important for activity is addressed by performing picosecond dynamic neutron scattering experiments on pig liver esterase powders at various temperatures as well as solutions. At all temperatures and hydrations investigated here, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. At low temperature, increasing hydration resulted in lower flexibility of the enzyme. At higher temperatures, systems containing sufficient number of water molecules interacting with the protein exhibit increased flexibility. The implication of these results is that, although the additional hydration-induced diffusive motion and flexibility at high temperatures in the enzyme detected here may be related to increased activity, they are not required for the enzyme to function

  2. Thermal conductivity measurements in unsaturated hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Cha, Jong-Ho; Rosenbaum, Eilis J.; Zhang, Wu; Seol, Yongkoo

    2015-08-01

    Current database on the thermal properties of hydrate-bearing sediments remains limited and has not been able to capture their consequential changes during gas production where vigorous phase changes occur in this unsaturated system. This study uses the transient plane source (TPS) technique to measure the thermal conductivity of methane hydrate-bearing sediments with various hydrate/water/gas saturations. We propose a simplified method to obtain thermal properties from single-sided TPS signatures. Results reveal that both volume fraction and distribution of the pore constituents govern the thermal conductivity of unsaturated specimens. Thermal conductivity hysteresis is observed due to water redistribution and fabric change caused by hydrate formation and dissociation. Measured thermal conductivity increases evidently when hydrate saturation Sh > 30-40%, shifting upward from the geometric mean model prediction to a Pythagorean mixing model. These observations envisage a significant drop in sediment thermal conductivity when residual hydrate/water saturation falls below ~40%, hindering further gas production.

  3. Dissolution mechanisms of CO2 hydrate droplets in deep seawaters

    International Nuclear Information System (INIS)

    Gabitto, Jorge; Tsouris, Costas

    2006-01-01

    Carbon dioxide dissolution at intermediate ocean depths was studied using physical and mass transfer models. Particle density and hydrate layer thickness were determined using existing field data. Pseudo-homogeneous and heterogeneous mass transfer models were proposed to study the dissolution process. Pseudo-homogeneous models do not seem to represent the dissolution process well. Although heterogeneous models interpret the physical behavior better, unresolved issues related to hydrate dissolution still remain. For example, solid hydrate forms on one side of the hydrate film while it dissolves on the other. Dissolution is a complex process that comprises at least two sequential steps. The global process is controlled by mass transfer inside the hydrate layer or by a dissolution reaction at the hydrate-water interface

  4. Natural gas storage in hydrates with the presence of promoters

    International Nuclear Information System (INIS)

    Sun Zhigao; Wang Ruzhu; Ma Rongsheng; Guo Kaihua; Fan Shuanshi

    2003-01-01

    Hydrate technology is being developed for the storage and transport of natural gas. Micellar surfectant solutions were found to increase the gas hydrate formation rate and storage capacity. An anionic surfactant, a nonionic surfactant, their mixtures and cyclopentane were used to improve the hydrate formation of a synthetic natural gas (methane=92.05 mol%, ethane=4.96 mol%, propane=2.99 mol%) in a quiescent system in this work. The effect of an anionic surfactant (sodium dodecyl sulfate) on natural gas storage in hydrates is more pronounced compared to the effect of a nonionic surfactant (dodecyl polysaccharide glycoside). Cyclopentane could reduce hydrate formation induction time but could not improve the hydrate formation rate and storage capacity

  5. Effects of pressure and temperature on the self-assembled fully hydrated nanostructures of monoolein-oil systems

    Czech Academy of Sciences Publication Activity Database

    Yaghmur, A.; Kriechbaum, M.; Amenitsch, H.; Steinhart, Miloš; Laggner, P.; Rappolt, M.

    2010-01-01

    Roč. 26, č. 2 (2010), s. 1177-1185 ISSN 0743-7463 R&D Projects: GA ČR GA202/09/2078 Institutional research plan: CEZ:AV0Z40500505 Keywords : lyotropic lipid mesophases * X-ray-diffraction * bicontinuous cubic phases Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.269, year: 2010

  6. A coupled THMC model of a heating and hydration laboratory experiment in unsaturated compacted FEBEX bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Samper, J.; Montenegro, L.; Fernandez, A.M.

    2010-05-01

    Unsaturated compacted bentonite is foreseen by several countries as a backfill and sealing material in high-level radioactive waste repositories. The strong interplays between thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the hydration stage of a repository call for fully coupled THMC models. Validation of such THMC models is prevented by the lack of comprehensive THMC experiments and the difficulties of experimental methods to measure accurately the chemical composition of bentonite porewater. We present here a non-isothermal multiphase flow and multicomponent reactive solute transport model for a deformable medium of a heating and hydration experiment performed on a sample of compacted FEBEX bentonite. Besides standard solute transport and geochemical processes, the model accounts for solute cross diffusion and thermal and chemical osmosis. Bentonite swelling is solved with a state-surface approach. The THM model is calibrated with transient temperature, water content and porosity data measured at the end of the experiment. The reactive transport model is calibrated with porewater chemical data derived from aqueous extract data. Model results confirm that thermal osmosis is relevant for the hydration of FEBEX bentonite while chemical osmosis can be safely neglected. Dilution and evaporation are the main processes controlling the concentration of conservative species. Dissolved cations are mostly affected by calcite dissolution-precipitation and cation exchange reactions. Dissolved sulphate is controlled by gypsum/anhydrite dissolution-precipitation. pH is mostly buffered by protonation/deprotonation via surface complexation. Computed concentrations agree well with inferred aqueous extract data at all sections except near the hydration boundary where cation data are affected by a sampling artifact. The fit of Cl{sup -} data is excellent except for the data near the heater. The largest deviations of the model from inferred aqueous

  7. Obsidian hydration profiles measured by sputter-induced optical emission.

    Science.gov (United States)

    Tsong, I S; Houser, C A; Yusef, N A; Messier, R F; White, W B; Michels, J W

    1978-07-28

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the phenomena underlying the obsidian hydration dating technique.

  8. [Laser Raman Spectroscopy and Its Application in Gas Hydrate Studies].

    Science.gov (United States)

    Fu, Juan; Wu, Neng-you; Lu, Hai-long; Wu, Dai-dai; Su, Qiu-cheng

    2015-11-01

    Gas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spectroscopy and summarizes its application in gas hydrate studies. Based on Raman results, not only can the information about gas composition and structural type be deduced, but also the occupancies of large and small cages and even hydration number can be calculated from the relative intensities of Raman peaks. By using the in-situ analytical technology, laser Raman specstropy can be applied to characterize the formation and decomposition processes of gas hydrate at microscale, for example the enclathration and leaving of gas molecules into/from its cages, to monitor the changes in gas concentration and gas solubility during hydrate formation and decomposition, and to identify phase changes in the study system. Laser Raman in-situ analytical technology has also been used in determination of hydrate structure and understanding its changing process under the conditions of ultra high pressure. Deep-sea in-situ Raman spectrometer can be employed for the in-situ analysis of the structures of natural gas hydrate and their formation environment. Raman imaging technology can be applied to specify the characteristics of crystallization and gas distribution over hydrate surface. With the development of laser Raman technology and its combination with other instruments, it will become more powerful and play a more significant role in the microscopic study of gas hydrate.

  9. Characteristics of Methane Hydrate Formation in Artificial and Natural Media

    OpenAIRE

    Peng Zhang; Qingbai Wu; Yuzhong Yang

    2013-01-01

    The formation of methane hydrate in two significantly different media was investigated, using silica gel as an artificial medium and loess as a natural medium. The methane hydrate formation was observed through the depletion of water in the matrix, measured via the matrix potential and the relationship between the matrix potential and the water content was determined using established equations. The velocity of methane hydrate nucleation slowed over the course of the reaction, as it relied on...

  10. Small angle neutron scattering from hydrated cement pastes

    International Nuclear Information System (INIS)

    Sabine, T.M.; Bertram, W.K.; Aldridge, L.P.

    1996-01-01

    Small angle neutron scattering (SANS) was used to study the microstructure of hydrating cement made with, and without silica fume. Some significant differences were found between the SANS spectra of pastes made from OPC (ordinary Portland cement) and DSP (made with silica fume and superplasticiser). The SANS spectra are interpreted in terms of scattering from simple particles. Particle growth was monitored during hydration and it was found that the growth correlated with the heat of hydration of the cement

  11. Nuclear Well Log Properties of Natural Gas Hydrate Reservoirs

    Science.gov (United States)

    Burchwell, A.; Cook, A.

    2015-12-01

    Characterizing gas hydrate in a reservoir typically involves a full suite of geophysical well logs. The most common method involves using resistivity measurements to quantify the decrease in electrically conductive water when replaced with gas hydrate. Compressional velocity measurements are also used because the gas hydrate significantly strengthens the moduli of the sediment. At many gas hydrate sites, nuclear well logs, which include the photoelectric effect, formation sigma, carbon/oxygen ratio and neutron porosity, are also collected but often not used. In fact, the nuclear response of a gas hydrate reservoir is not known. In this research we will focus on the nuclear log response in gas hydrate reservoirs at the Mallik Field at the Mackenzie Delta, Northwest Territories, Canada, and the Gas Hydrate Joint Industry Project Leg 2 sites in the northern Gulf of Mexico. Nuclear logs may add increased robustness to the investigation into the properties of gas hydrates and some types of logs may offer an opportunity to distinguish between gas hydrate and permafrost. For example, a true formation sigma log measures the thermal neutron capture cross section of a formation and pore constituents; it is especially sensitive to hydrogen and chlorine in the pore space. Chlorine has a high absorption potential, and is used to determine the amount of saline water within pore spaces. Gas hydrate offers a difference in elemental composition compared to water-saturated intervals. Thus, in permafrost areas, the carbon/oxygen ratio may vary between gas hydrate and permafrost, due to the increase of carbon in gas hydrate accumulations. At the Mallik site, we observe a hydrate-bearing sand (1085-1107 m) above a water-bearing sand (1107-1140 m), which was confirmed through core samples and mud gas analysis. We observe a decrease in the photoelectric absorption of ~0.5 barnes/e-, as well as an increase in the formation sigma readings of ~5 capture units in the water-bearing sand as

  12. Impact of welan gum on tricalcium aluminate–gypsum hydration

    International Nuclear Information System (INIS)

    Ma Lei; Zhao Qinglin; Yao Chukang; Zhou Mingkai

    2012-01-01

    The retarding effect of welan gum on tricalcium aluminate–gypsum hydration, as a partial system of ordinary Portland cement (OPC) hydration, was investigated with several methods. The tricalcium aluminate–gypsum hydration behavior in the presence or absence of welan gum was researched by field emission gun scanning electron microscopy, X-ray diffraction and zeta potential analysis. Meanwhile, we studied the surface electrochemical properties and adsorption characteristics of welan gum by utilizing a zeta potential analyzer and UV–VIS absorption spectrophotometer. By adding welan gum, the morphology change of ettringite and retardation of hydration stages in tricalcium aluminate–gypsum system was observed. Moreover, we detected the adsorption behavior and zeta potential inversion of tricalcium aluminate and ettringite, as well as a rapid decrease in the zeta potential of tricalcium aluminate–gypsum system. The reduction on nucleation rate of ettringite and hydration activity of C 3 A was also demonstrated. Thus, through the adsorption effect, welan gum induces a retarding behavior in tricalcium aluminate–gypsum hydration. Highlights: ► Adsorption characteristics of welan gum on C 3 A and ettringite have been studied. ► C 3 A–gypsum hydration behavior and the hydration products are examined in L/S = 3. ► Welan gum retards the process of C 3 A–gypsum hydration. ► The addition of welan gum changes the nucleation growth of ettringite.

  13. Geomechanical Performance of Hydrate-Bearing Sediment in Offshore Environments

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; Tad Patzek; Jonny Rutqvist; George Moridis; Richard Plumb

    2008-03-31

    The objective of this multi-year, multi-institutional research project was to develop the knowledge base and quantitative predictive capability for the description of geomechanical performance of hydrate-bearing sediments (hereafter referred to as HBS) in oceanic environments. The focus was on the determination of the envelope of hydrate stability under conditions typical of those related to the construction and operation of offshore platforms. We have developed a robust numerical simulator of hydrate behavior in geologic media by coupling a reservoir model with a commercial geomechanical code. We also investigated the geomechanical behavior of oceanic HBS using pore-scale models (conceptual and mathematical) of fluid flow, stress analysis, and damage propagation. The objective of the UC Berkeley work was to develop a grain-scale model of hydrate-bearing sediments. Hydrate dissociation alters the strength of HBS. In particular, transformation of hydrate clusters into gas and liquid water weakens the skeleton and, simultaneously, reduces the effective stress by increasing the pore pressure. The large-scale objective of the study is evaluation of geomechanical stability of offshore oil and gas production infrastructure. At Lawrence Berkeley National Laboratory (LBNL), we have developed the numerical model TOUGH + Hydrate + FLAC3D to evaluate how the formation and disassociation of hydrates in seafloor sediments affects seafloor stability. Several technical papers were published using results from this model. LBNL also developed laboratory equipment and methods to produce realistic laboratory samples of sediments containing gas hydrates so that mechanical properties could be measured in the laboratory. These properties are required to run TOUGH + Hydrate + FLAC3D to evaluate seafloor stability issues. At Texas A&M University we performed a detailed literature review to determine what gas hydrate formation properties had been measured and reported in the literature. We

  14. Hydration of Portoguese cements, measurement and modelling of chemical shrinkage

    DEFF Research Database (Denmark)

    Maia, Lino; Geiker, Mette Rica; Figueiras, Joaquim A.

    2008-01-01

    form of the dispersion model. The development of hydration varied between the investigated cements; based on the measured data the degree of hydration after 24 h hydration at 20 C varied between 40 and 50%. This should be taken into account when comparing properties of concrete made from the different......Development of cement hydration was studied by measuring the chemical shrinkage of pastes. Five types of Portuguese Portland cement were used in cement pastes with . Chemical shrinkage was measured by gravimetry and dilatometry. In gravimeters results were recorded automatically during at least...

  15. Ethylene Separation via Hydrate Formation in W/O Emulsions

    Directory of Open Access Journals (Sweden)

    Yong Pan

    2015-05-01

    Full Text Available An hybrid absorption-hydration method was adopted to recover C2H4 from C2H4/CH4 binary gas mixtures and the hydrate formation conditions of C2H4/CH4 mixtures was studied experimentally in diesel in water (w/o emulsions. Span 20 at a concentration of 1.0 wt% in the aqueous phase was added to form water in diesel emulsions before hydrate formation and then hydrate in diesel slurry was separated after hydrate formation. The influences of initial gas-liquid volume ratio (53–142, pressure (3.4–5.4 MPa, temperature (274.15–278.15 K, water cuts (10–30 vol%, and the mole fraction of C2H4 in feed gas (13.19–80.44 mol% upon the C2H4 separation efficiency were systematically investigated. The experimental results show that ethylene can be enriched in hydrate slurry phase with high separation factor (S and recovery ratio (R. Most hydrate formation finished in 20 min, after that, the hydrate formation rate became very slow. The conclusion is useful for determining the suitable operation conditions when adopting an absorption-hydration method to separate C2H4/CH4.

  16. Methane Production and Carbon Capture by Hydrate Swapping

    DEFF Research Database (Denmark)

    Mu, Liang; von Solms, Nicolas

    2017-01-01

    There are essentially two different approaches to producing methane from natural gas hydrate reservoirs, either bring the hydrate out of its thermodynamic stability region or expose the hydrate to a substance that will form a more stable hydrate structure, forcing an in situ swapping of the trapped...... experimental runs were performed to examine the influence of operating conditions on methane production by CO2/(CO2 + N2) injection in the temperature range of 274.15–277.15 K and 7.039–10.107 MPa pressure. Our results show that the use of the (CO2 + N2) binary gas mixture is advantageous compared to the use...

  17. HYDRATION AND MICROSTRUCTURE OF BLENDED CEMENT WITH SODIUM POLYSTYRENE SULFONATE

    Directory of Open Access Journals (Sweden)

    Weifeng Li

    2017-03-01

    Full Text Available Polystyrene foamed plastic wastes are a kind of environmental pollutant. It could be recycled in cement industry as a chemical agent. In this paper, the effects of sodium polystyrene sulfonate (SPS on the hydration and microstructure of blended cement were investigated by calorimetry, X-ray diffraction (XRD, scanning electron microscopy (SEM and mercury intrusion porosimetry (MIP. SPS slightly delayed the hydration of alite and decreased its hydration degree. SPS did not change the phase compositions during hydration. SPS changed the morphology of ettringite (AFt and decreased the pore volumes and the sizes of pores.

  18. Effects of various vehicles on skin hydration in vivo.

    Science.gov (United States)

    Wiedersberg, S; Leopold, C S; Guy, R H

    2009-01-01

    The stratum corneum, the outermost layer of the skin, regulates the passive loss of water to the environment. Furthermore, it is well accepted that drug penetration is influenced by skin hydration, which may be manipulated by the application of moisturizing or oleaginous vehicles. Measurements of transepidermal water loss (TEWL), and of skin hydration using a corneometer, were used to assess the effect of different vehicles on stratum corneum barrier function in vivo in human volunteers. A microemulsion significantly increased skin hydration relative to a reference vehicle based on medium chain triglycerides; in contrast, Transcutol(R) lowered skin hydration. TEWL measurements confirmed these observations. Copyright 2009 S. Karger AG, Basel.

  19. Fully Depleted Charge-Coupled Devices

    International Nuclear Information System (INIS)

    Holland, Stephen E.

    2006-01-01

    We have developed fully depleted, back-illuminated CCDs that build upon earlier research and development efforts directed towards technology development of silicon-strip detectors used in high-energy-physics experiments. The CCDs are fabricated on the same type of high-resistivity, float-zone-refined silicon that is used for strip detectors. The use of high-resistivity substrates allows for thick depletion regions, on the order of 200-300 um, with corresponding high detection efficiency for near-infrared and soft x-ray photons. We compare the fully depleted CCD to the p-i-n diode upon which it is based, and describe the use of fully depleted CCDs in astronomical and x-ray imaging applications

  20. CMOS current controlled fully balanced current conveyor

    International Nuclear Information System (INIS)

    Wang Chunhua; Zhang Qiujing; Liu Haiguang

    2009-01-01

    This paper presents a current controlled fully balanced second-generation current conveyor circuit (CF-BCCII). The proposed circuit has the traits of fully balanced architecture, and its X-Y terminals are current controllable. Based on the CFBCCII, two biquadratic universal filters are also proposed as its applications. The CFBCCII circuits and the two filters were fabricated with chartered 0.35-μm CMOS technology; with ±1.65 V power supply voltage, the total power consumption of the CFBCCII circuit is 3.6 mW. Comparisons between measured and HSpice simulation results are also given.

  1. Fully exponentially correlated wavefunctions for small atoms

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Frank E. [Department of Physics, University of Utah, Salt Lake City, UT 84112 and Quantum Theory Project, University of Florida, P.O. Box 118435, Gainesville, FL 32611 (United States)

    2015-01-22

    Fully exponentially correlated atomic wavefunctions are constructed from exponentials in all the interparticle coordinates, in contrast to correlated wavefunctions of the Hylleraas form, in which only the electron-nuclear distances occur exponentially, with electron-electron distances entering only as integer powers. The full exponential correlation causes many-configuration wavefunctions to converge with expansion length more rapidly than either orbital formulations or correlated wavefunctions of the Hylleraas type. The present contribution surveys the effectiveness of fully exponentially correlated functions for the three-body system (the He isoelectronic series) and reports their application to a four-body system (the Li atom)

  2. Calibration and validation of a numerical model against experimental data of methane hydrate formation and dissociation in a sandy porous medium

    Science.gov (United States)

    Yin, Z.; Moridis, G. J.; Chong, Z. R.; Linga, P.

    2017-12-01

    Methane hydrates (MH) are known to trap enormous amounts of CH4 in oceanic and permafrost-associated deposits, and are being considered as a potential future energy source. Several powerful numerical simulators were developed to describe the behavior of natural hydrate-bearing sediments (HBS). The complexity and strong nonlinearities in HBS do not allow analytical solutions for code validation. The only reliable method to develop confidence in these models is through comparisons to laboratory and/or field experiments. The objective of this study is to reproduce numerically the results from earlier experiments of MH formation and depressurization (and the corresponding fluid production) in 1.0L reactor involving unconsolidated sand, thus validating and calibrating the TOUGH+Hydrate v1.5 simulator. We faithfully describe the reactor geometry and the experimental process that involves both hydrate formation and dissociation. We demonstrate that the laboratory experiments can only be captured by a kinetic hydration model. There is an excellent agreement between observations and predictions (a) of the cumulative gas depletion (during formation) and production (during dissociation) and (b) of pressure over time. The temperature agreement is less satisfactory, and the deviations are attributed to the fixed locations of the limited number of sensors that cannot fully capture the hydrate heterogeneity. We also predict the spatial distributions over time of the various phase (gas, aqueous and hydrate) saturations. Thus, hydrates form preferentially along the outer boundary of the sand core, and the hydrate front moves inward leaving a significant portion of the sand at the center hydrate-free. During depressurization, dissociation advances again inward from the reactor boundary to the center of the reactor. As expected, methane gas accumulates initially at the locations of most intense dissociation, and then gradually migrates to the upper section of the reactor because of

  3. Hydrated electron: a destroyer of perfluorinated carboxylates?

    International Nuclear Information System (INIS)

    Huang Li; Dong Wenbo; Hou Huiqi

    2006-01-01

    As a class, perfluorinated carboxylate (PFCA) was ranked among the most prominent organohalogen contaminants in environment with respect to thermal, chemical and biological inertness. Hydrated electron (e aq - ), a highly reactive and strongly reductive species, has been reported to readily decompose perfluoroaromatic compounds via intermolecular electron transfer process in aqueous solution. Question then arose: what would happen if perfluorinated carboxylates encountered with hydrated electron? Original laboratory trial on the interaction between F(CF 2 ) n COO - (n=1, 3, 7) and hydrated electron was attempted by using laser flash photolysis technique in this research work. Abundant hydrated electron (e aq - ) could be produced by photolysis of 1.25 x 10 -4 M K 4 Fe(CN) 6 in nitrogen saturated water. In the presence of F(CF 2 ) n COO - (n=1, 3, 7), the decay of e aq - was observed to enhance dramatically, indicating e aq - was able to attack PFCAs. On addition of perfluorinated carboxylates, the loss of e aq - was mainly due to the following channels. By mixing the solution of K 4 Fe(CN) 6 with excess K 3 Fe(CN) 6 and PFCAs, e aq - turned to decayed corresponding to mixed first- and second-order kinetics. Rate constants for the reactions of e aq - with PFCAs could be then easily determined by monitoring the decay of e aq - absorption at 690 nm. Since perfluorinated carboxylates were salts, the influence of ionic strength on k 3 was examined systematically by carrying out experiments of varying ionic strength ranging from 0.009 up to 0.102 M by adding NaClO 4 . In this manner, the second order rate constants for e-aq with CF 3 COO - , C 3 F 7 COO - , C 7 F 15 COO - were derived to be (1.9±0.2) x 10 6 M -1 S -1 (μ=0), (7.1±0.2) x 10 6 M -1 S -1 (μ=0) and (1.7±0.5) x10 7 M -1 S -1 (μ=0.009 M) respectively. Apparently, the length of F(CF 2 ) n group exerted substantial influence on the rate constant. Further study on byproducts analysis by ion chromatography

  4. Life Origination Hydrate Hypothesis (LOH-Hypothesis

    Directory of Open Access Journals (Sweden)

    Victor Ostrovskii

    2012-01-01

    Full Text Available The paper develops the Life Origination Hydrate Hypothesis (LOH-hypothesis, according to which living-matter simplest elements (LMSEs, which are N-bases, riboses, nucleosides, nucleotides, DNA- and RNA-like molecules, amino-acids, and proto-cells repeatedly originated on the basis of thermodynamically controlled, natural, and inevitable processes governed by universal physical and chemical laws from CH4, niters, and phosphates under the Earth's surface or seabed within the crystal cavities of the honeycomb methane-hydrate structure at low temperatures; the chemical processes passed slowly through all successive chemical steps in the direction that is determined by a gradual decrease in the Gibbs free energy of reacting systems. The hypothesis formulation method is based on the thermodynamic directedness of natural movement and consists ofan attempt to mentally backtrack on the progression of nature and thus reveal principal milestones alongits route. The changes in Gibbs free energy are estimated for different steps of the living-matter origination process; special attention is paid to the processes of proto-cell formation. Just the occurrence of the gas-hydrate periodic honeycomb matrix filled with LMSEs almost completely in its final state accounts for size limitation in the DNA functional groups and the nonrandom location of N-bases in the DNA chains. The slowness of the low-temperature chemical transformations and their “thermodynamic front” guide the gross process of living matter origination and its successive steps. It is shown that the hypothesis is thermodynamically justified and testable and that many observed natural phenomena count in its favor.

  5. A DFT-based comparative equilibrium study of thermal dehydration and hydrolysis of CaCl2 hydrates and MgCl2 hydrates for seasonal heat storage

    NARCIS (Netherlands)

    Pathak, A.D.; Gaastra-Nedea, S.V.; Zondag, H.A.; Rindt, C.C.M.; Smeulders, D.M.J.

    2016-01-01

    Salt hydrates store solar energy in chemical form via a reversible dehydration–hydration reaction. However, as a side reaction to dehydration, hydrolysis (HCl formation) may occur in chloride based salt hydrates (specially in MgCl2 hydrates), affecting the durability of the storage system. The

  6. Suspension hydration of C3S [tricalcium silicate] at constant pH. II. Effect of previously formed hydrates and of additives

    NARCIS (Netherlands)

    McCurdy, K.G.; Stein, H.N.

    1973-01-01

    A retardation shown by the hydration of C3S at pH=11.5 can be prevented if before the addition of C3S there are present hydrate particles in the aqueous medium. These hydrate particles probably have the composition CSHn. This indicates a hydrate CSHn, precipitated from solution, as the retarding

  7. Withholding hydration and nutrition in newborns.

    Science.gov (United States)

    Porta, Nicolas; Frader, Joel

    2007-01-01

    In the twenty-first century, decisions to withhold or withdraw life-supporting measures commonly precede death in the neonatal intensive care unit without major ethical controversy. However, caregivers often feel much greater turmoil with regard to stopping medical hydration and nutrition than they do when considering discontinuation of mechanical ventilation or circulatory support. Nevertheless, forgoing medical fluids and food represents a morally acceptable option as part of a carefully developed palliative care plan considering the infant's prognosis and the burdens of continued treatment. Decisions to stop any form of life support should focus on the clinical circumstances, not the means used to sustain life.

  8. Well log characterization of natural gas-hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2012-01-01

    In the last 25 years there have been significant advancements in the use of well-logging tools to acquire detailed information on the occurrence of gas hydrates in nature: whereas wireline electrical resistivity and acoustic logs were formerly used to identify gas-hydrate occurrences in wells drilled in Arctic permafrost environments, more advanced wireline and logging-while-drilling (LWD) tools are now routinely used to examine the petrophysical nature of gas-hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Resistivity- and acoustic-logging tools are the most widely used for estimating the gas-hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. Recent integrated sediment coring and well-log studies have confirmed that electrical-resistivity and acoustic-velocity data can yield accurate gas-hydrate saturations in sediment grain-supported (isotropic) systems such as sand reservoirs, but more advanced log-analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. New well-logging tools designed to make directionally oriented acoustic and propagation-resistivity log measurements provide the data needed to analyze the acoustic and electrical anisotropic properties of both highly interbedded and fracture-dominated gas-hydrate reservoirs. Advancements in nuclear magnetic resonance (NMR) logging and wireline formation testing (WFT) also allow for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids(i.e., free water along with clay- and capillary-bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms

  9. Investigating the Metastability of Clathrate Hydrates for Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Carolyn Ann [Colorado School of Mines, Golden, CO (United States)

    2014-11-18

    Important breakthrough discoveries have been achieved from the DOE award on the key processes controlling the synthesis and structure-property relations of clathrate hydrates, which are critical to the development of clathrate hydrates as energy storage materials. Key achievements include: (i) the discovery of key clathrate hydrate building blocks (stable and metastable) leading to clathrate hydrate nucleation and growth; (ii) development of a rapid clathrate hydrate synthesis route via a seeding mechanism; (iii) synthesis-structure relations of H2 + CH4/CO2 binary hydrates to control thermodynamic requirements for energy storage and sequestration applications; (iv) discovery of a new metastable phase present during clathrate hydrate structural transitions. The success of our research to-date is demonstrated by the significant papers we have published in high impact journals, including Science, Angewandte Chemie, J. Am. Chem. Soc. Intellectual Merits of Project Accomplishments: The intellectual merits of the project accomplishments are significant and transformative, in which the fundamental coupled computational and experimental program has provided new and critical understanding on the key processes controlling the nucleation, growth, and thermodynamics of clathrate hydrates containing hydrogen, methane, carbon dioxide, and other guest molecules for energy storage. Key examples of the intellectual merits of the accomplishments include: the first discovery of the nucleation pathways and dominant stable and metastable structures leading to clathrate hydrate formation; the discovery and experimental confirmation of new metastable clathrate hydrate structures; the development of new synthesis methods for controlling clathrate hydrate formation and enclathration of molecular hydrogen. Broader Impacts of Project Accomplishments: The molecular investigations performed in this project on the synthesis (nucleation & growth)-structure-stability relations of clathrate

  10. Free energy landscape and molecular pathways of gas hydrate nucleation

    International Nuclear Information System (INIS)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu

    2016-01-01

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p B histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p B histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  11. Free energy landscape and molecular pathways of gas hydrate nucleation.

    Science.gov (United States)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu

    2016-12-07

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p B histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p B histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  12. Free energy landscape and molecular pathways of gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu, E-mail: tsli@gwu.edu [Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052 (United States)

    2016-12-07

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p{sub B} histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p{sub B} histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  13. Behaviour of gas production from type 3 hydrate reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Pooladi-Darvish, M. [Calgary Univ., AB (Canada). Dept. of Chemical and Petroleum Engineering]|[Fekete Associates Inc., Calgary, AB (Canada); Zatsepina, O. [Calgary Univ., AB (Canada). Dept. of Chemical and Petroleum Engineering; Hong, H. [Fekete Associates Inc., Calgary, AB (Canada)

    2008-07-01

    The possible role of gas hydrates as a potential energy resource was discussed with particular reference to methods for estimating the rate of gas production from hydrate reservoirs under different operating conditions. This paper presented several numerical simulations studies of gas production from type 3 hydrate reservoirs in 1-D and 2-D geometries. Type 3 reservoirs include gas production from hydrate-reservoirs that lie totally within the hydrate stability zone and are sandwiched by impermeable layers on top and bottom. The purpose of this study was to better understand hydrate decomposition by depressurization. The study questioned whether 1-D modeling of type 3 hydrate reservoirs is a reasonable approximation. It also determined whether gas rate increases or decreases with time. The important reservoir characteristics for determining the rate of gas production were identified. Last, the study determined how competition between fluid and heat flow affects hydrate decomposition. This paper also described the relation and interaction between the heat and fluid flow mechanisms in depressurization of type 3 hydrate reservoirs. All results of 1-D and 2-D numerical simulation and analyses were generated using the STARS simulator. It was shown that the rate of gas production depends on the initial pressure/temperature conditions and permeability of the hydrate bearing formation. A high peak rate may be achieved under favourable conditions, but this peak rate is obtained after an initial period where the rate of gas production increases with time. The heat transfer in the direction perpendicular to the direction of fluid flow is significant, requiring 2D modeling. The hydraulic diffusivity is low because of the low permeability of hydrate-bearing formations. This could result in competition between heat and fluid flow, thereby influencing the behaviour of decomposition. 6 refs., 3 tabs., 12 figs.

  14. Quantum Fully Homomorphic Encryption with Verification

    DEFF Research Database (Denmark)

    Alagic, Gorjan; Dulek, Yfke; Schaffner, Christian

    2017-01-01

    Fully-homomorphic encryption (FHE) enables computation on encrypted data while maintaining secrecy. Recent research has shown that such schemes exist even for quantum computation. Given the numerous applications of classical FHE (zero-knowledge proofs, secure two-party computation, obfuscation, e...

  15. Fully conditional specification in multivariate imputation

    NARCIS (Netherlands)

    van Buuren, S.; Brand, J. P.L.; Groothuis-Oudshoorn, C. G.M.; Rubin, D. B.

    2006-01-01

    The use of the Gibbs sampler with fully conditionally specified models, where the distribution of each variable given the other variables is the starting point, has become a popular method to create imputations in incomplete multivariate data. The theoretical weakness of this approach is that the

  16. Fully Integrated Biochip Platforms for Advanced Healthcare

    Directory of Open Access Journals (Sweden)

    Giovanni De Micheli

    2012-08-01

    Full Text Available Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications.

  17. Fully integrated biochip platforms for advanced healthcare.

    Science.gov (United States)

    Carrara, Sandro; Ghoreishizadeh, Sara; Olivo, Jacopo; Taurino, Irene; Baj-Rossi, Camilla; Cavallini, Andrea; de Beeck, Maaike Op; Dehollain, Catherine; Burleson, Wayne; Moussy, Francis Gabriel; Guiseppi-Elie, Anthony; De Micheli, Giovanni

    2012-01-01

    Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications.

  18. Equipment for fully automatic radiographic pipe inspection

    International Nuclear Information System (INIS)

    Basler, G.; Sperl, H.; Weinschenk, K.

    1977-01-01

    The patent describes a device for fully automatic radiographic testing of large pipes with longitudinal welds. Furthermore the invention enables automatic marking of films in radiographic inspection with regard to a ticketing of the test piece and of that part of it where testing took place. (RW) [de

  19. Faster Fully-Dynamic minimum spanning forest

    DEFF Research Database (Denmark)

    Holm, Jacob; Rotenberg, Eva; Wulff-Nilsen, Christian

    2015-01-01

    We give a new data structure for the fully-dynamic minimum spanning forest problem in simple graphs. Edge updates are supported in O(log4 n/log logn) expected amortized time per operation, improving the O(log4 n) amortized bound of Holm et al. (STOC’98, JACM’01).We also provide a deterministic data...

  20. Nasogastric Hydration in Infants with Bronchiolitis Less Than 2 Months of Age.

    Science.gov (United States)

    Oakley, Ed; Bata, Sonny; Rengasamy, Sharmila; Krieser, David; Cheek, John; Jachno, Kim; Babl, Franz E

    2016-11-01

    To determine whether nasogastric hydration can be used in infants less than 2 months of age with bronchiolitis, and characterize the adverse events profile of these infants compared with infants given intravenous (IV) fluid hydration. A descriptive retrospective cohort study of children with bronchiolitis under 2 months of age admitted for hydration at 3 centers over 3 bronchiolitis seasons was done. We determined type of hydration (nasogastric vs IV fluid hydration) and adverse events, intensive care unit admission, and respiratory support. Of 491 infants under 2 months of age admitted with bronchiolitis, 211 (43%) received nonoral hydration: 146 (69%) via nasogastric hydration and 65 (31%) via IV fluid hydration. Adverse events occurred in 27.4% (nasogastric hydration) and 23.1% (IV fluid hydration), difference of 4.3%; 95%CI (-8.2 to 16.9), P = .51. The majority of adverse events were desaturations (21.9% nasogastric hydration vs 21.5% IV fluid hydration, difference 0.4%; [-11.7 to 12.4], P = .95). There were no pulmonary aspirations in either group. Apneas and bradycardias were similar in each group. IV fluid hydration use was positively associated with intensive care unit admission (38.5% IV fluid hydration vs 19.9% nasogastric hydration; difference 18.6%, [5.1-32.1], P = .004); and use of ventilation support (27.7% IV fluid hydration vs 15.1% nasogastric hydration; difference 12.6 [0.3-23], P = .03). Fewer infants changed from nasogastric hydration to IV fluid hydration than from IV fluid hydration to nasogastric hydration (12.3% vs 47.7%; difference -35.4% [-49 to -22], P hydration can be used in the majority of young infants admitted with bronchiolitis. Nasogastric hydration and IV fluid hydration had similar rates of complications. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. 76 FR 36176 - Fully Developed Claim (Fully Developed Claims-Applications for Compensation, Pension, DIC, Death...

    Science.gov (United States)

    2011-06-21

    ... DEPARTMENT OF VETERANS AFFAIRS [OMB Control No. 2900-0747] Fully Developed Claim (Fully Developed Claims--Applications for Compensation, Pension, DIC, Death Pension, and/or Accrued Benefits); Correction AGENCY: Veterans Benefits Administration, Department of Veterans Affairs. ACTION: Notice; correction...

  2. A unified approach for description of gas hydrate formation kinetics in the presence of kinetic promoters in gas hydrate converters

    International Nuclear Information System (INIS)

    ZareNezhad, Bahman; Varaminian, Farshad

    2013-01-01

    Highlights: • A unified kinetic model for description of promoted and non-promoted gas hydrate formation processes is presented. • Effects of impeller speed, promoter concentration and different kinetic promoters are investigated. • A unique region of gas hydrate formation is identified regarding gas hydrate formation processes. • The proposed model is useful for understanding the behavior of gas hydrate formation processes and design of GTH converters. - Abstract: The kinetic promoters have found wide applications in enhancing the rate of energy conversion and storage via gas hydrate formation processes. Effects of different kinetic promoters such as anionic surfactants sodium dodecyl sulfate (SDS), dodecylbenzene sulfonic acid (DBSA), and sodium dodecyl benzene sulfonate (SDBS); cationic surfactants, Cetyl trimethyl ammonium bromide (CTAB), dodecyl trimethyl ammonium bromide (DTAB) and non-ionic surfactants, alkylpolyglucoside (APG), dodecyl polysaccharide glycoside (DPG), TritonX-100 (TX100) on methane (CH 4 ), ethane (C 2 H 6 ) and propane (C 3 H 8 ) gas hydrate formation processes are investigated in this work. A macroscopic kinetic model based on the time variations of reaction chemical potential is also presented for global description of gas hydrate formation processes. Experimental gas hydrate formation data are employed to validate the proposed kinetic model. Effects of promoter’s concentrations and agitation intensities on the gas consumption profiles are also investigated. A universal correlation and a unified kinetic map have been proposed for macroscopic description of gas hydrate formation kinetics in the presence or absence of kinetic promoters. According to the presented unified kinetic map, a unique region of gas hydrate formation is identified for the first time. For negligible amounts of kinetic promoters, the presented region disappears and approaches to a unique path at high agitation intensities. The presented unified approach is

  3. Prospects of gas hydrate presence in the Chukchi sea

    Directory of Open Access Journals (Sweden)

    Т. В. Матвеева

    2017-08-01

    Full Text Available The purpose of this study is to forecast the scale and distribution character of gas hydrate stability zone in the Chukchi Sea under simulated natural conditions and basing on these results to estimate resource potential of gas hydrates within this area. Three types of stability zone have been identified. A forecast map of gas hydrate environment and potentially gas hydrate-bearing water areas in the Chukchi Sea has been plotted to a scale of 1:5 000 000. Mapping of gas hydrate stability zone allowed to give a justified forecast based on currently available data on geologic, fluid dynamic, cryogenic, geothermal and pressure-temperature conditions of gas hydrate formation in the Chukchi Sea. It is the first forecast of such kind that focuses on formation conditions for hydrates of various types and compositions in the Arctic seas offshore Russia. Potential amount of gas, stored beneath the Chukchi Sea in the form of hydrates, is estimated based on mapping of their stability zone and falls into the interval of 7·1011-11.8·1013 m3.

  4. Exploring the solid-form landscape of pharmaceutical hydrates

    DEFF Research Database (Denmark)

    Raijada, Dharaben Kaushikkumar; Bond, Andrew; Larsen, Flemming Hofmann

    2013-01-01

    To understand the transformation pathways amongst anhydrate/hydrate solid forms of sodium naproxen and to highlight the importance of a polymorphic dihydrate within this context.......To understand the transformation pathways amongst anhydrate/hydrate solid forms of sodium naproxen and to highlight the importance of a polymorphic dihydrate within this context....

  5. Hydration behaviour of synthetic saponite at variable relative humidity

    Indian Academy of Sciences (India)

    Hydration behaviour of synthetic saponite was examined by X-ray powder diffraction simulation at various relative humidities (RH). The basal spacing of the Ca-saponite increased stepwise with increase in RH. The (00) reflections observed reflect single or dual hydration states of smectite. Quasi-rational, intermediate, or ...

  6. The effect of stereochemistry on carbohydrate hydration in aqueous solutions

    NARCIS (Netherlands)

    Galema, Saskia Alexandra

    1992-01-01

    Although-carbohydrates are widely used, not much is known about the stereochemical aspects of hydration of carbohydrates. For D-aldohexoses, for example, there are eight different stereoisomers. Just how the hydroxy topology of a carbohydrate molecule influences the hydration behaviour in water is

  7. Spectroscopic determination of optimal hydration time of zircon surface

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia R, G. [Instituto Tecnologico de Toluca, Division de Estudios del Posgrado, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Garcia G, N., E-mail: eduardo.ordonez@inin.gob.m [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Av. Colon y Av. Tollocan, 50180 Toluca, Estado de Mexico (Mexico)

    2010-07-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO{sub 4}) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy{sup 3+}, Eu{sup 3+} and Er{sup 3} in the bulk of zircon. The Dy{sup 3+} is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy{sup 3+} has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  8. Spectroscopic determination of optimal hydration time of zircon surface

    International Nuclear Information System (INIS)

    Ordonez R, E.; Garcia R, G.; Garcia G, N.

    2010-01-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO 4 ) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy 3+ , Eu 3+ and Er 3 in the bulk of zircon. The Dy 3+ is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy 3+ has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  9. Evaluation of Nutritional Status and Hydration in Patients on Chronic ...

    African Journals Online (AJOL)

    Background: Nutrition and hydration of the dialysis patients have major influences on the outcomes of chronic hemodialysis. Purpose: To characterize the states of nutrition and hydration in patients on chronic hemodialysis at Jos University Teaching Hospital (JUTH) and to evaluate the usefulness of measurements by ...

  10. Phase equilibrium condition of marine carbon dioxide hydrate

    International Nuclear Information System (INIS)

    Sun, Shi-Cai; Liu, Chang-Ling; Ye, Yu-Guang

    2013-01-01

    Highlights: ► CO 2 hydrate phase equilibrium was studied in simulated marine sediments. ► CO 2 hydrate equilibrium temperature in NaCl and submarine pore water was depressed. ► Coarse-grained silica sand does not affect CO 2 hydrate phase equilibrium. ► The relationship between equilibrium temperature and freezing point was discussed. - Abstract: The phase equilibrium of ocean carbon dioxide hydrate should be understood for ocean storage of carbon dioxide. In this paper, the isochoric multi-step heating dissociation method was employed to investigate the phase equilibrium of carbon dioxide hydrate in a variety of systems (NaCl solution, submarine pore water, silica sand + NaCl solution mixture). The experimental results show that the depression in the phase equilibrium temperature of carbon dioxide hydrate in NaCl solution is caused mainly by Cl − ion. The relationship between the equilibrium temperature and freezing point in NaCl solution was discussed. The phase equilibrium temperature of carbon dioxide hydrate in submarine pore water is shifted by −1.1 K to lower temperature region than that in pure water. However, the phase equilibrium temperature of carbon dioxide hydrate in mixture samples of coarsed-grained silica sand and NaCl solution is in agreement with that in NaCl solution with corresponding concentrations. The relationship between the equilibrium temperature and freezing point in mixture samples was also discussed.

  11. Unexpected Hydration of a Triple Bond During DNA Synthesis

    DEFF Research Database (Denmark)

    Fatthalla, Maha I.; Pedersen, Erik B.

    2016-01-01

    acidic conditions, polarizes the triple bond in the intercalator and this makes hydration of the triple bond possible during the DNA synthesis and an oligonucleotide with 1-(indol-3-yl)-2-(pyren-1-yl)ethanone as the intercalator is formed. Insertion of the unhydrated and hydrated linker systems gave...

  12. Solubility data for cement hydrate phases (25oC)

    International Nuclear Information System (INIS)

    Atkins, M.; Glasser, F.P.; Kindness, A.; Macphee, D.E.

    1991-05-01

    Solubility measurements were performed on most of the more thermodynamically-stable cement hydrate phases, at 25 o C. The results for each hydrate phase are summarised in the form of datasheets. Solubility properties are discussed, and where possible a K sp value is calculated. The data are compared with the data in the literature. (author)

  13. Potential natural gas hydrates resources in Indian Offshore areas

    Digital Repository Service at National Institute of Oceanography (India)

    Sethi, A.K.; Sathe, A.V.; Ramana, M.V.

    (geophysical proxies of gas hydrates). A qualitative map prepared based on the inferred BSRs brought out a deepwater area of about 80,000 sq.km unto 3000 m isobath as favourable for gas hydrate occurrence. Methodology for reprocessing of seismic data...

  14. Gas hydrate inhibition by perturbation of liquid water structure

    Science.gov (United States)

    Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Lee, Kun-Hong

    2015-06-01

    Natural gas hydrates are icy crystalline materials that contain hydrocarbons, which are the primary energy source for this civilization. The abundance of naturally occurring gas hydrates leads to a growing interest in exploitation. Despite their potential as energy resources and in industrial applications, there is insufficient understanding of hydrate kinetics, which hinders the utilization of these invaluable resources. Perturbation of liquid water structure by solutes has been proposed to be a key process in hydrate inhibition, but this hypothesis remains unproven. Here, we report the direct observation of the perturbation of the liquid water structure induced by amino acids using polarized Raman spectroscopy, and its influence on gas hydrate nucleation and growth kinetics. Amino acids with hydrophilic and/or electrically charged side chains disrupted the water structure and thus provided effective hydrate inhibition. The strong correlation between the extent of perturbation by amino acids and their inhibition performance constitutes convincing evidence for the perturbation inhibition mechanism. The present findings bring the practical applications of gas hydrates significantly closer, and provide a new perspective on the freezing and melting phenomena of naturally occurring gas hydrates.

  15. Putting the Deep Biosphere and Gas Hydrates on the Map

    Science.gov (United States)

    Sikorski, Janelle J.; Briggs, Brandon R.

    2016-01-01

    Microbial processes in the deep biosphere affect marine sediments, such as the formation of gas hydrate deposits. Gas hydrate deposits offer a large source of natural gas with the potential to augment energy reserves and affect climate and seafloor stability. Despite the significant interdependence between life and geology in the ocean, coverage…

  16. NMR Studies of Protein Hydration and Protein-Ligand Interactions

    Science.gov (United States)

    Chong, Yuan

    Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

  17. Theoretical description of biomolecular hydration - Application to A-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, A.E.; Hummer, G. [Los Alamos National Laboratory, NM (United States); Soumpasis, D.M. [Max Planck Inst. for Biophysical Chemistry, Goettingen (Germany)

    1994-12-31

    The local density of water molecules around a biomolecule is constructed from calculated two- and three-points correlation functions of polar solvents in water using a Potential-of-Mean-Force (PMF) expansion. As a simple approximation, the hydration of all polar (including charged) groups in a biomolecule is represented by the hydration of water oxygen in bulk water, and the effect of non-polar groups on hydration are neglected, except for excluded volume effects. Pair and triplet correlation functions are calculated by molecular dynamics simulations. We present calculations of the structural hydration for ideal A-DNA molecules with sequences [d(CG){sub 5}]{sub 2} and [d(C{sub 5}G{sub 5})]{sub 2}. We find that this method can accurately reproduce the hydration patterns of A-DNA observed in neutron diffraction experiments on oriented DNA fibers.

  18. Seismic-Scale Rock Physics of Methane Hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Amos Nur

    2009-01-08

    We quantify natural methane hydrate reservoirs by generating synthetic seismic traces and comparing them to real seismic data: if the synthetic matches the observed data, then the reservoir properties and conditions used in synthetic modeling might be the same as the actual, in-situ reservoir conditions. This approach is model-based: it uses rock physics equations that link the porosity and mineralogy of the host sediment, pressure, and hydrate saturation, and the resulting elastic-wave velocity and density. One result of such seismic forward modeling is a catalogue of seismic reflections of methane hydrate which can serve as a field guide to hydrate identification from real seismic data. We verify this approach using field data from known hydrate deposits.

  19. Gas hydrate phase equilibria measurement techniques and phase rule considerations

    International Nuclear Information System (INIS)

    Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip

    2012-01-01

    Highlights: → Inconsistencies found in hydrate literature. → Clarification to the number of variables needed to satisfy and justify equilibrium data. → Application of phase rule to mixed hydrate systems. → Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

  20. Hydration of Portland cement with additions of calcium sulfoaluminates

    International Nuclear Information System (INIS)

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

    2013-01-01

    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.

  1. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    as the rhabdophane structure is preserved. The bound hydrate water is accommodated in the rhabdophane structure and is stable at temperatures of up to 650 oC. The thermal stability of the hydrate water and the phosphate structure are of significance for the proton conductivity. The LaPO4·0.6H2O and NdPO4•0.5H2O......Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...... to the monazite structure upon dehydration. The thermal stability of the hydrate is studied and found to contain water of two types, physically adsorbed and structurally bound hydrate water. The adsorbed water is correlated to the specific surface area and can be reversibly recovered when dehydrated as long...

  2. Water Dynamics in the Hydration Shells of Biomolecules

    Science.gov (United States)

    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

  3. Theoretical description of biomolecular hydration - Application to A-DNA

    International Nuclear Information System (INIS)

    Garcia, A.E.; Hummer, G.; Soumpasis, D.M.

    1994-01-01

    The local density of water molecules around a biomolecule is constructed from calculated two- and three-points correlation functions of polar solvents in water using a Potential-of-Mean-Force (PMF) expansion. As a simple approximation, the hydration of all polar (including charged) groups in a biomolecule is represented by the hydration of water oxygen in bulk water, and the effect of non-polar groups on hydration are neglected, except for excluded volume effects. Pair and triplet correlation functions are calculated by molecular dynamics simulations. We present calculations of the structural hydration for ideal A-DNA molecules with sequences [d(CG) 5 ] 2 and [d(C 5 G 5 )] 2 . We find that this method can accurately reproduce the hydration patterns of A-DNA observed in neutron diffraction experiments on oriented DNA fibers

  4. Skin Hydration Assessment through Modern Non-Invasive Bioengineering Technologies.

    Science.gov (United States)

    Constantin, Maria-Magdalena; Poenaru, Elena; Poenaru, Calin; Constantin, Traian

    2014-03-01

    Non-invasive bioengineering technologies continuously discovered and developed in recent decades provide a significant input to research development and remarkably contribute to the improvement of medical education and care to our patients. Assessing skin hydration by using the capacitance method for a group of patients with allergic contact dermatitis versus healthy subjects, before and after applying a moisturiser (assessing the immediate and long-term effectiveness of hydration). For both groups, but especially for the patients with dry skin, there was a clear improvement of hydration, statistically significant after applying the moisturiser. In the case of the patients with allergic contact dermatitis, hydration was at a maximum immediately after the first application, and then maintained an increased level after 7 and 28 days, respectively. In the healthy subjects, the increase in hydration was lower, but progressive. The moisturiser determined an increase in hydration for all age groups, but those who showed the most obvious effect were the young adults (18-29 years old) with an increase of 19.9%.The maintenance effect of hydration lasted for 28 days, while the improvement was important for allergic skin (17.1%) and significant for healthy skin (10.9%). The assessment of epidermal hydration performed by using the corneometer showed very good hydration of the stratum corneum for both groups studied, with immediate and long-term effect. This study also showed that the degree of skin hydration was inversely proportional with age. The corneometer is easy to use, efficient and widely utilised in international studies for measurements in healthy or pathological conditions, for quantitative assessment of the effectiveness of various preparations intended for application to the skin surface, under well-controlled and standardised conditions.

  5. Reflective terahertz (THz) imaging: system calibration using hydration phantoms

    Science.gov (United States)

    Bajwa, Neha; Garritano, James; Lee, Yoon Kyung; Tewari, Priyamvada; Sung, Shijun; Maccabi, Ashkan; Nowroozi, Bryan; Babakhanian, Meghedi; Sanghvi, Sajan; Singh, Rahul; Grundfest, Warren; Taylor, Zachary

    2013-02-01

    Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein, was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with statistically significant hydration sensitivities (p hydration). The THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and intervention of corneal pathologies.

  6. Advanced Gas Hydrate Reservoir Modeling Using Rock Physics

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, Daniel

    2017-12-30

    Prospecting for high saturation gas hydrate deposits can be greatly aided with improved approaches to seismic interpretation and especially if sets of seismic attributes can be shown as diagnostic or direct hydrocarbon indicators for high saturation gas hydrates in sands that would be of most interest for gas hydrate production.

    A large 3D seismic data set in the deep water Eastern Gulf of Mexico was screened for gas hydrates using a set of techniques and seismic signatures that were developed and proven in the Central deepwater Gulf of Mexico in the DOE Gulf of Mexico Joint Industry Project JIP Leg II in 2009 and recently confirmed with coring in 2017.

    A large gas hydrate deposit is interpreted in the data where gas has migrated from one of the few deep seated faults plumbing the Jurassic hydrocarbon source into the gas hydrate stability zone. The gas hydrate deposit lies within a flat-lying within Pliocene Mississippi Fan channel that was deposited outboard in a deep abyssal environment. The uniform architecture of the channel aided the evaluation of a set of seismic attributes that relate to attenuation and thin-bed energy that could be diagnostic of gas hydrates. Frequency attributes derived from spectral decomposition also proved to be direct hydrocarbon indicators by pseudo-thickness that could be only be reconciled by substituting gas hydrate in the pore space. The study emphasizes that gas hydrate exploration and reservoir characterization benefits from a seismic thin bed approach.

  7. Rainwater drained through fully filled pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, B; Koestel, P

    1989-02-01

    The conventional rainwater drainage system according to DIN 1986 always seems to be a point of problemacy in the building services as far as the occupancy of installation shafts and ducts is at stake. The excavation work and the necessary gravity lines are considered to be expensive. The consideration of the necessary slope complicates the installation additionally. Basing on those considerations, the raindraining system with fully filled pipes has been developed. DIN 1986, edition June 1988, part 1, point 6.1.1 allows to install rainwater pipes operated as planned, fully filled without slope. An enterprise specialised in building services investigated all system laws because only by a hydraulically exact balance, the function of the rainwater drainage system operated by negative and positive pressure can be insured. The results of those investigations are integrated in a computer program developed for this purpose.

  8. Developments towards a fully automated AMS system

    International Nuclear Information System (INIS)

    Steier, P.; Puchegger, S.; Golser, R.; Kutschera, W.; Priller, A.; Rom, W.; Wallner, A.; Wild, E.

    2000-01-01

    The possibilities of computer-assisted and automated accelerator mass spectrometry (AMS) measurements were explored. The goal of these efforts is to develop fully automated procedures for 'routine' measurements at the Vienna Environmental Research Accelerator (VERA), a dedicated 3-MV Pelletron tandem AMS facility. As a new tool for automatic tuning of the ion optics we developed a multi-dimensional optimization algorithm robust to noise, which was applied for 14 C and 10 Be. The actual isotope ratio measurements are performed in a fully automated fashion and do not require the presence of an operator. Incoming data are evaluated online and the results can be accessed via Internet. The system was used for 14 C, 10 Be, 26 Al and 129 I measurements

  9. Ultrasonic sound speed of hydrating calcium sulphate hemihydrate; part 2, the correlation of sound velocity to hydration degree

    NARCIS (Netherlands)

    de Korte, A.C.J.; Brouwers, Jos; Fischer, H.B; Matthes, C.; Beuthan, C.

    2011-01-01

    In this article the sound velocity through a mix is correlated to the hydration degree of the mix. Models are presented predicting the sound velocity through fresh slurries and hardened products. These two states correspond to the starting and finishing point of the hydration process. The present

  10. Ultrasonic sound speed of hydrating calcium sulphate hemihydrate; Part 2, The correlation of sound velocity to hydration degree

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.; Fischer, H.B.; Mattes, Chr.; Beutha, C.

    2011-01-01

    In this article the sound velocity through a mix is correlated to the hydration degree of the mix. Models are presented predicting the sound velocity through fresh slurries and hardened products. These two states correspond to the starting and finishing point of the hydration process. The present

  11. Geologic implications of gas hydrates in the offshore of India: Results of the National Gas Hydrate Program Expedition 01

    Digital Repository Service at National Institute of Oceanography (India)

    Collett, T.S.; Boswell, R.; Cochran, J.R.; Kumar, P.; Lall, M.; Mazumdar, A.; Ramana, M.V.; Ramprasad, T.; Riedel, M.; Sain, K.; Sathe, A.V.; Vishwanath, K.; NGHP Expedition 01 Scientific Party

    in Japan (Tsujii et al., 2009) and in the Gulf of Mexico (Boswell et al., 2012a) and the pace of gas-hydrate energy-assessment projects continues to accelerate. Beyond a future energy resource, gas hydrates may in some cases represent a significant...

  12. A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

    International Nuclear Information System (INIS)

    Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jorgen

    2006-01-01

    Recent 27 Al MAS NMR studies of hydrated Portland cements and calcium-silicate-hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known aluminate species in hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered aluminate hydrate which contains Al(OH) 6 3- or O x Al(OH) 6-x (3+x)- units. The formation of the new aluminate hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70-90 o C. From the experiments in this work it is proposed that the new aluminate hydrate is either an amorphous/disordered aluminate hydroxide or a calcium aluminate hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed

  13. FMFT. Fully massive four-loop tadpoles

    Energy Technology Data Exchange (ETDEWEB)

    Pikelner, Andrey [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2017-07-15

    We present FMFT - a package written in FORM that evaluates four-loop fully massive tadpole Feynman diagrams. It is a successor of the MATAD package that has been successfully used to calculate many renormalization group functions at three-loop order in a wide range of quantum field theories especially in the Standard Model. We describe an internal structure of the package and provide some examples of its usage.

  14. Fully NLO Parton Shower in QCD

    International Nuclear Information System (INIS)

    Skrzypek, M.; Jadach, S.; Slawinska, M.; Gituliar, O.; Kusina, A.; Placzek, W.

    2011-01-01

    The project of constructing a complete NLO-level Parton Shower Monte Carlo for the QCD processes developed in IFJ PAN in Krakow is reviewed. Four issues are discussed: (1) the extension of the standard inclusive collinear factorization into a new, fully exclusive scheme; (2) reconstruction of the LO Parton Shower in the new scheme; (3) inclusion of the exclusive NLO corrections into the hard process and (4) inclusion of the exclusive NLO corrections into the evolution (ladder) part. (authors)

  15. FMFT: fully massive four-loop tadpoles

    Science.gov (United States)

    Pikelner, Andrey

    2018-03-01

    We present FMFT - a package written in FORM that evaluates four-loop fully massive tadpole Feynman diagrams. It is a successor of the MATAD package that has been successfully used to calculate many renormalization group functions at three-loop order in a wide range of quantum field theories especially in the Standard Model. We describe an internal structure of the package and provide some examples of its usage.

  16. Fully probabilistic design of hierarchical Bayesian models

    Czech Academy of Sciences Publication Activity Database

    Quinn, A.; Kárný, Miroslav; Guy, Tatiana Valentine

    2016-01-01

    Roč. 369, č. 1 (2016), s. 532-547 ISSN 0020-0255 R&D Projects: GA ČR GA13-13502S Institutional support: RVO:67985556 Keywords : Fully probabilistic design * Ideal distribution * Minimum cross-entropy principle * Bayesian conditioning * Kullback-Leibler divergence * Bayesian nonparametric modelling Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 4.832, year: 2016 http://library.utia.cas.cz/separaty/2016/AS/karny-0463052.pdf

  17. Structural determinants of hydration, mechanics and fluid flow in freeze-dried collagen scaffolds.

    Science.gov (United States)

    Offeddu, G S; Ashworth, J C; Cameron, R E; Oyen, M L

    2016-09-01

    Freeze-dried scaffolds provide regeneration templates for a wide range of tissues, due to their flexibility in physical and biological properties. Control of structure is crucial for tuning such properties, and therefore scaffold functionality. However, the common approach of modeling these scaffolds as open-cell foams does not fully account for their structural complexity. Here, the validity of the open-cell model is examined across a range of physical characteristics, rigorously linking morphology to hydration and mechanical properties. Collagen scaffolds with systematic changes in relative density were characterized using Scanning Electron Microscopy, X-ray Micro-Computed Tomography and spherical indentation analyzed in a time-dependent poroelastic framework. Morphologically, all scaffolds were mid-way between the open- and closed-cell models, approaching the closed-cell model as relative density increased. Although pore size remained constant, transport pathway diameter decreased. Larger collagen fractions also produced greater volume swelling on hydration, although the change in pore diameter was constant, and relatively small at ∼6%. Mechanically, the dry and hydrated scaffold moduli varied quadratically with relative density, as expected of open-cell materials. However, the increasing pore wall closure was found to determine the time-dependent nature of the hydrated scaffold response, with a decrease in permeability producing increasingly elastic rather than viscoelastic behavior. These results demonstrate that characterizing the deviation from the open-cell model is vital to gain a full understanding of scaffold biophysical properties, and provide a template for structural studies of other freeze-dried biomaterials. Freeze-dried collagen sponges are three-dimensional microporous scaffolds that have been used for a number of exploratory tissue engineering applications. The characterization of the structure-properties relationships of these scaffolds is

  18. Fully implicit kinetic modelling of collisional plasmas

    International Nuclear Information System (INIS)

    Mousseau, V.A.

    1996-05-01

    This dissertation describes a numerical technique, Matrix-Free Newton Krylov, for solving a simplified Vlasov-Fokker-Planck equation. This method is both deterministic and fully implicit, and may not have been a viable option before current developments in numerical methods. Results are presented that indicate the efficiency of the Matrix-Free Newton Krylov method for these fully-coupled, nonlinear integro-differential equations. The use and requirement for advanced differencing is also shown. To this end, implementations of Chang-Cooper differencing and flux limited Quadratic Upstream Interpolation for Convective Kinematics (QUICK) are presented. Results are given for a fully kinetic ion-electron problem with a self consistent electric field calculated from the ion and electron distribution functions. This numerical method, including advanced differencing, provides accurate solutions, which quickly converge on workstation class machines. It is demonstrated that efficient steady-state solutions can be achieved to the non-linear integro-differential equation, obtaining quadratic convergence, without incurring the large memory requirements of an integral operator. Model problems are presented which simulate plasma impinging on a plate with both high and low neutral particle recycling typical of a divertor in a Tokamak device. These model problems demonstrate the performance of the new solution method

  19. Investigation of C3 S hydration mechanism by transmission electron microscope (TEM) with integrated Super-XTM EDS system.

    Science.gov (United States)

    Sakalli, Y; Trettin, R

    2017-07-01

    Tricalciumsilicate (C 3 S, Alite) is the major component of the Portland cement clinker. Hydration of Alite is decisive in influencing the properties of the resulting material. This is due to its high content in cement. The mechanism of the hydration of C 3 S is very complicated and not yet fully understood. There are different models describing the hydration of C 3 S in various ways. In this work for a better understanding of hydration mechanism, the hydrated C 3 S was investigated by using the transmission electron microscope (TEM) and for the first time, the samples for the investigations were prepared by using of focused ion beam from sintered pellets of C 3 S. Also, an FEI Talos F200x with an integrated Super-X EDS system was used for the investigations. FEI Talos F200X combines outstanding high-resolution S/TEM and TEM imaging with energy dispersive X-ray spectroscopy signal detection, and 3D chemical characterization with compositional mapping. TEM is a very powerful tool for material science. A high energy beam of electrons passes through a very thin sample, and the interactions between the electrons and the atoms can be used to observe the structure of the material and other features in the structure. TEM can be used to study the growth of layers and their composition. TEM produces high-resolution, two-dimensional images and will be used for a wide range of educational, science and industry applications. Chemical analysis can also be performed. The purpose of these investigations was to get the information about the composition of the C-S-H phases and some details of the nanostructure of the C-S-H phases. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  20. Solid-state 27Al and 29Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

    International Nuclear Information System (INIS)

    Pena, P.; Rivas Mercury, J.M.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

    2008-01-01

    Partially deuterated Ca 3 Al 2 (SiO 4 ) y (OH) 12-4y -Al(OH) 3 mixtures, prepared by hydration of Ca 3 Al 2 O 6 (C 3 A), Ca 12 Al 14 O 33 (C 12 A 7 ) and CaAl 2 O 4 (CA) phases in the presence of silica fume, have been characterized by 29 Si and 27 Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca 3 Al 2 (OH) 12 and Al(OH) 3 phases were detected. From the quantitative analysis of 27 Al NMR signals, the Al(OH) 3 /Ca 3 Al 2 (OH) 12 ratio was deduced. The incorporation of Si into the katoite structure, Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x , was followed by 27 Al and 29 Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of 27 Al MAS-NMR components associated with Al(OH) 6 and Al(OSi)(OH) 5 environments. The 29 Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From 29 Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures. - Graphical abstract: Transmission electron micrograph of CaAl 2 O 4 -microsilica mixture hydrated at 90 deg. C for 31 days showing a cubic Ca 3 Al 2.0±0.2 (SiO 4 ) 0.9±0.2 (OH) 1.8 crystal surrounded by unreacted amorphous silica spheres

  1. Methane Recycling During Burial of Methane Hydrate-Bearing Sediments

    Science.gov (United States)

    You, K.; Flemings, P. B.

    2017-12-01

    We quantitatively investigate the integral processes of methane hydrate formation from local microbial methane generation, burial of methane hydrate with sedimentation, and methane recycling at the base of the hydrate stability zone (BHSZ) with a multiphase multicomponent numerical model. Methane recycling happens in cycles, and there is not a steady state. Each cycle starts with free gas accumulation from hydrate dissociation below the BHSZ. This free gas flows upward under buoyancy, elevates the hydrate saturation and capillary entry pressure at the BHSZ, and this prevents more free gas flowing in. Later as this layer with elevated hydrate saturation is buried and dissociated, the large amount of free gas newly released and accumulated below rapidly intrudes into the hydrate stability zone, drives rapid hydrate formation and creates three-phase (gas, liquid and hydrate) equilibrium above the BHSZ. The gas front retreats to below the BHSZ until all the free gas is depleted. The shallowest depth that the free gas reaches in one cycle moves toward seafloor as more and more methane is accumulated to the BHSZ with time. More methane is stored above the BHSZ in the form of concentrated hydrate in sediments with relatively uniform pore throat, and/or with greater compressibility. It is more difficult to initiate methane recycling in passive continental margins where the sedimentation rate is low, and in sediments with low organic matter content and/or methanogenesis reaction rate. The presence of a permeable layer can store methane for significant periods of time without recycling. In a 2D system where the seafloor dips rapidly, the updip gas flow along the BHSZ transports more methane toward topographic highs where methane gas and elevated hydrate saturation intrude deeper into the hydrate stability zone within one cycle. This could lead to intermittent gas venting at seafloor at the topographic highs. This study provides insights on many phenomenon associated with

  2. Manufacture of Methane Hydrate using Carbon Nano Tubes

    International Nuclear Information System (INIS)

    Park, Sung Seek

    2010-02-01

    Methane hydrate is formed by physical binding between water molecule and gas such as methane, ethane, propane, or carbon dioxide, etc., which is captured in the cavities of water molecule under the specific temperature and pressure. More than 99% of naturally produced methane hydrate consists of methane, and is widely dispersed in the continental slope and continental Shelf of the Pacific and the Atlantic, the Antarctica etc. The reserve of fossil fuel is 500 billion carbon ton and the reserve of methane is 360 million carbon ton. The reserve of gas hydrate is more than 1 trillion carbon ton, which is twice the fossil fuel. Therefore, natural gas hydrate as a kind of gas hydrate is expected to replace fossil fuel as new energy source of 21st century. Also 1 m 3 hydrate of pure methane can be decomposed to the maximum of 216 m 3 methane at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18∼25% less than the liquefied transportation. However, when natural gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation focuses on the rapid production of hydrates and increases gas consumption by adding MWCNT and NaCl into pure water. The results show that the equilibrium pressure in seawater is more higher than that in pure water, and methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 9K or above in seawater and 8K or above in pure water, respectively. Also, amount of consumed gas volume in pure water is more higher that in seawater at the same experimental conditions

  3. Moessbauer study of hydrated iron sulfates

    International Nuclear Information System (INIS)

    Araujo, S.I.; Danon, J.; Iannarella, L.

    1991-01-01

    The hydrated iron sulfates amarantite Fe(SO sub(4))(OH).3H sub(2)O, copiapite (Mg,Al)Fe sup(3+) sub(4)(SO sub(4)) sub(6)(OH) sub(2).20H sub(2)O and ungemachite K sub(3)Na sub(9)Fe(SO sub(4)) sub(6)(OH) sub(3).9H sub(2)O were studied by Moessbauer Spectroscopy (MS) in connection with Differential Scanning Calorimetry (DSC). The effect of the dehydration on the hyperfine parameters at the Fe sites was investigated. For amarantite, the Moessbauer spectrum remained practically unchanged, while the Fe sup(3+) quadrupole splittings for copiapite and ungemachite increased. The Fe sup(2+) quadrupole splitting of ungemachite was also unchanged. We have found out the anisotropy of the recoiless absorption probability for the sup(57)Fe Moessbauer gamma ray in amarantite. The three minerals were found to be highly hygroscopic after the dehydration consequent of the DSC measurements. (author)

  4. DNA under Force: Mechanics, Electrostatics, and Hydration

    Directory of Open Access Journals (Sweden)

    Jingqiang Li

    2015-02-01

    Full Text Available Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

  5. Irradiation effects in hydrated zirconium molybdate

    Energy Technology Data Exchange (ETDEWEB)

    Fourdrin, C., E-mail: chloe.fourdrin@polytechnique.edu [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91 191 Gif-sur-Yvette (France); CEA Saclay, DSM/IRAMIS/SIS2M-UMR 3299/Lrad, 91 191 Gif-sur-Yvette (France); Esnouf, S. [CEA Saclay, DSM/IRAMIS/SIS2M-UMR 3299/Lrad, 91 191 Gif-sur-Yvette (France); Dauvois, V. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91 191 Gif-sur-Yvette (France); Renault, J.-P. [CEA Saclay, DSM/IRAMIS/SIS2M-UMR 3299/Lrad, 91 191 Gif-sur-Yvette (France); Venault, L. [CEN Valrho, DEN/DRCP/SCPS/LC2A, 30 207 Bagnols-sur-Ceze (France); Tabarant, M. [CEA Saclay, DEN/DANS/DPC/LRSI, 91 191 Gif-sur-Yvette (France); Durand, D. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91 191 Gif-sur-Yvette (France); Cheniere, A. [CEA Saclay, DEN/DANS/DPC/LRSI, 91 191 Gif-sur-Yvette (France); Lamouroux-Lucas, C. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91 191 Gif-sur-Yvette (France); Cochin, F. [AREVA NC Tour, AREVA, 92 084 Paris La Defense cedex (France)

    2012-07-15

    Hydrated zirconium molybdate is a precipitate formed during the process of spent nuclear fuel dissolution. In order to study the radiation stability of this material, we performed gamma and electron irradiation in a dose range of 10-100 kGy. XRD patterns showed that the crystalline structure is not affected by irradiation. However, the yellow original sample exhibits a blue-grey color after exposure. The resulting samples were analyzed by means of EPR and diffuse reflectance spectroscopy. Two sites for trapped electrons were evidenced leading to a d{sup 1} configuration responsible for the observed coloration. Moreover, a third defect corresponding to a hole trapped on oxygen was observed after electron irradiation at low temperature.

  6. Dehydration of hydrated low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T

    1949-01-01

    Yoshida examined the mechanism of the dehydration of hydrated low-temperature tar with a microscope. The tar containing free carbon and coal dust is so stable that the removal of the above substances and water by a physical method is very difficult. Addition of light oil produced by fractionation of low-temperature tar facilitates the operations. Yoshida tried using the separate acid, neutral, and basic components of the light oil; the acid oil proved to be most effective. For many reasons it is convenient to use light oil as it is. In this method the quantity of light oil required is 2 to 3 times that of tar. But in supplementing the centrifugal method, the quantity of light oil needed might be only half the amount of tar.

  7. Characterizing heterogeneous dynamics at hydrated electrode surfaces

    Science.gov (United States)

    Willard, Adam P.; Limmer, David T.; Madden, Paul A.; Chandler, David

    2013-05-01

    In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

  8. Characterizing heterogeneous dynamics at hydrated electrode surfaces.

    Science.gov (United States)

    Willard, Adam P; Limmer, David T; Madden, Paul A; Chandler, David

    2013-05-14

    In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

  9. High-pressure structures of methane hydrate

    International Nuclear Information System (INIS)

    Hirai, H; Uchihara, Y; Fujihisa, H; Sakashita, M; Katoh, E; Aoki, K; Yamamoto, Y; Nagashima, K; Yagi, T

    2002-01-01

    Three high-pressure structures of methane hydrate, a hexagonal structure (str. A) and two orthorhombic structures (str. B and str. C), were found by in situ x-ray diffractometry and Raman spectroscopy. The well-known structure I (str. I) decomposed into str. A and fluid at 0.8 GPa. Str. A transformed into str. B at 1.6 GPa, and str. B further transformed into str. C at 2.1 GPa which survived above 7.8 GPa. The fluid solidified as ice VI at 1.4 GPa, and the ice VI transformed to ice VII at 2.1 GPa. The bulk moduli, K 0 , for str. I, str. A, and str. C were calculated to be 7.4, 9.8, and 25.0 GPa, respectively

  10. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  11. Influence of Physical Activity and Ambient Temperature on Hydration: The European Hydration Research Study (EHRS

    Directory of Open Access Journals (Sweden)

    Ricardo Mora-Rodriguez

    2016-04-01

    Full Text Available This study explored the effects of physical activity (PA and ambient temperature on water turnover and hydration status. Five-hundred seventy three healthy men and women (aged 20–60 years from Spain, Greece and Germany self-reported PA, registered all food and beverage intake, and collected 24-h urine during seven consecutive days. Fasting blood samples were collected at the onset and end of the study. Food moisture was assessed using nutritional software to account for all water intake which was subtracted from daily urine volume to allow calculation of non-renal water loss (i.e., mostly sweating. Hydration status was assessed by urine and blood osmolality. A negative association was seen between ambient temperature and PA (r = −0.277; p < 0.001. Lower PA with high temperatures did not prevent increased non-renal water losses (i.e., sweating and elevated urine and blood osmolality (r = 0.218 to 0.163 all p < 0.001. When summer and winter data were combined PA was negatively associated with urine osmolality (r = −0.153; p = 0.001. Our data suggest that environmental heat acts to reduce voluntary PA but this is not sufficient to prevent moderate dehydration (increased osmolality. On the other hand, increased PA is associated with improved hydration status (i.e., lower urine and blood osmolality.

  12. Introduction of the 2007-2008 JOGMEC/NRCan/Aurora Mallik Gas Hydrate Production Research Program, NWT, Canada

    Science.gov (United States)

    Yamamoto, K.; Dallimore, S. R.; Numasawa, M.; Yasuda, M.; Fujii, T.; Fujii, K.; Wright, J.; Nixon, F.

    2007-12-01

    Japan Oil, Gas and Metals National Corporation (JOGMEC) and Natural Resource Canada (NRCan) have embarked on a new research program to study the production potential of gas hydrates. The program is being carried out at the Mallik gas hydrate field in the Mackenzie Delta, a location where two previous scientific investigations have been carried in 1998 and 2002. In the 2002 program that was undertaken by seven partners from five countries, 468m3 of gas flow was measured during 124 hours of thermal stimulation using hot warm fluid. Small-scale pressure drawdown tests were also carried out using Schlumberger's Modular Dynamics Tester (MDT) wireline tool, gas flow was observed and the inferred formation permeabilities suggested the possible effectiveness of the simple depressurization method. While the testing undertaken in 2002 can be cited as the first well constrained gas production from a gas hydrate deposit, the results fell short of that required to fully calibrate reservoir simulation models or indeed establish the technical viability of long term production from gas hydrates. The objectives of the current JOGMEC/NRCan/Aurora Mallik production research program are to undertake longer term production testing to further constrain the scientific unknowns and to demonstrate the technical feasibility of sustained gas hydrate production using the depressurization method. A key priority is to accurately measure water and gas production using state-of-art production technologies. The primary production test well was established during the 2007 field season with the re-entry and deepening of JAPEX/JNOC/GSC Mallik 2L-38 well, originally drilled in 1998. Production testing was carried out in April of 2007 under a relatively low drawdown pressure condition. Flow of methane gas was measured from a 12m perforated interval of gas-hydrate-saturated sands from 1093 to 1105m. The results establish the potential of the depressurization method and provide a basis for future

  13. The investigation of lithium formate hydrate, sodium dithionate and N-methyl taurine as clinical EPR dosimeters

    International Nuclear Information System (INIS)

    Lelie, S.; Hole, E.O.; Duchateau, M.; Schroeyers, W.; Schreurs, S.; Verellen, D.

    2013-01-01

    Introduction: EPR-dosimetry using L-α-alanine is an established method for measuring high doses of ionizing radiation. However, since a minimum dose of approximately 4 Gy is required to achieve sufficient low uncertainties (1–2%) for clinical application, alternative dosimeter materials are being inquired. Lithium formate (LiFo) monohydrate has been studied by several groups and has revealed several promising properties in the low dose region (<4 Gy). The fading properties, however, are somewhat unpredictable, and depend on properties not yet fully uncovered. This paper reports the results from a study of lithium formate hydrate and N-methyl taurine as potential low dose EPR dosimeters. Methods and materials: Pellet shaped dosimeters of lithium formate monohydrate, lithium formate hydrate, sodium dithionate and N-methyl taurine were produced using a manual Weber press, L-α-alanine was obtained from Harwell dosimeters and irradiated using 60 kV and 6 MV X-ray beams, and Co-60 gamma-rays to a dose of 30 Gy and dose ranges of 0.5–100 Gy and 2–20 Gy respectively. The dosimeters were measured using an Electron Paramagnetic Resonance (EPR)-spectrometer. The detector responses for 6 MV and Co-60 radiation beams, the fading behaviors and signal shape in time were investigated. Results: Lithium formate monohydrate and lithium formate hydrate are apparently associated with near identical EPR-spectra (mainly one broad line), and the same spectrum arises for all radiation energies investigated. The shape of the EPR resonance remains constant with time, but the intensities decreases, and the fading is more prominent for the monohydrate than for the hydrate. The EPR resonance associated with N-methyl taurine is more complex than the resonance associated with LiFo and it changes with time, implying radical transitions and growth. Conclusions: The study showed that lithium formate hydrate is a strong candidate for EPR dosimetry with slightly better fading characteristics

  14. Balancing Accuracy and Computational Efficiency for Ternary Gas Hydrate Systems

    Science.gov (United States)

    White, M. D.

    2011-12-01

    Geologic accumulations of natural gas hydrates hold vast organic carbon reserves, which have the potential of meeting global energy needs for decades. Estimates of vast amounts of global natural gas hydrate 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 hydrate 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 hydrate deposits requires releasing CH4 from solid gas hydrate. The conventional way to release CH4 is to dissociate the hydrate by changing the pressure and temperature conditions to those where the hydrate 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 hydrate reservoir. Numerical simulation of the production of gas hydrates 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 hydrate system comprises five components (i.e., H2O, CH4, CO2, N2, and salt) and the potential for six phases (i.e., aqueous, liquid CO2, gas, hydrate, ice, and precipitated salt). The equation of state for ternary hydrate systems has three requirements: 1) phase occurrence, 2) phase composition, and 3) phase properties. Numerical simulation of the production of geologic accumulations of gas hydrates have historically suffered from relatively slow execution times, compared with other multifluid, porous media systems, due to strong nonlinearities and

  15. Precise structural analysis of methane hydrate by neutron diffraction

    International Nuclear Information System (INIS)

    Igawa, Naoki; Hoshikawa, Akinori; Ishii, Yoshinobu

    2006-01-01

    Methane hydrate has attracted great interest as an energy resource to replace natural gas since this material is deposited in the seafloor and the deposits are estimated to exceed those of natural gas. Understanding the physical proprieties, such as the temperature dependence of the crystal structure, helps to specify the optimum environmental temperature and pressure during drilling, transport, and storage of methane hydrate. Clathrate hydrates consisted of encaging atomic and/or molecular species as a guest and host water formed by a hydrogen bonding. Although many studies on the clathrate hydrate including methane hydrate were reported, no detailed crystallographic property has yet been cleared. We focused on the motion of methane in the clathrate hydrate by the neutron diffraction. The crystal structure of the methane hydrate was analyzed by the applying the combination of the Rietveld refinement and the maximum entropy method (MEM) to neutron powder diffraction. Temperature dependence of the scattering-length density distribution maps revealed that the motion of methane molecules differs between the shapes of dodecahedron and tetrakaidecahedron. (author)

  16. CLATHRATE HYDRATES FORMATION IN SHORT-PERIOD COMETS

    International Nuclear Information System (INIS)

    Marboeuf, Ulysse; Mousis, Olivier; Petit, Jean-Marc; Schmitt, Bernard

    2010-01-01

    The initial composition of current models of cometary nuclei is only based on two forms of ice: crystalline ice for long-period comets and amorphous ice for short-period comets. A third form of ice, i.e., clathrate hydrate, could exist within the short-period cometary nuclei, but the area of formation of this crystalline structure in these objects has never been studied. Here, we show that the thermodynamic conditions in the interior of short-period comets allow the existence of clathrate hydrates in Halley-type comets. We show that their existence is viable in the Jupiter family comets only when the equilibrium pressure of CO clathrate hydrate is at least 1 order of magnitude lower than the usually assumed theoretical value. We calculate that the amount of volatiles that could be trapped in the clathrate hydrate layer may be orders of magnitude greater than the daily amount of gas released at the surface of the nucleus at perihelion. The formation and the destruction of the clathrate hydrate cages could then explain the diversity of composition of volatiles observed in comets, as well as some pre-perihelion outbursts. We finally show that the potential clathrate hydrate layer in comet 67P/Churyumov-Gerasimenko would, unfortunately, be deep inside the nucleus, out of reach of the Rosetta lander. However, such a clathrate hydrate layer would show up by the gas composition of the coma.

  17. The effect of hydrate promoters on gas uptake.

    Science.gov (United States)

    Xu, Chun-Gang; Yu, Yi-Song; Ding, Ya-Long; Cai, Jing; Li, Xiao-Sen

    2017-08-16

    Gas hydrate technology is considered as a promising technology in the fields of gas storage and transportation, gas separation and purification, seawater desalination, and phase-change thermal energy storage. However, to date, the technology is still not commercially used mainly due to the low gas hydrate formation rate and the low gas uptake. In this study, the effect of hydrate promoters on gas uptake was systematically studied and analyzed based on hydrate-based CH 4 storage and CO 2 capture from CO 2 /H 2 gas mixture experiments. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC) were employed to analyze the microstructures and gas compositions. The results indicate that the effect of the hydrate promoter on the gas uptake depends on the physical and chemical properties of the promoter and gas. A strong polar ionic promoter is not helpful towards obtaining the ideal gas uptake because a dense hydrate layer is easily formed at the gas-liquid interface, which hinders gas diffusion from the gas phase to the bulk solution. For a weak polar or non-polar promoter, the gas uptake depends on the dissolution characteristics among the different substances in the system. The lower the mutual solubility among the substances co-existing in the system, the higher the independence among the substances in the system; this is so that each phase has an equal chance to occupy the hydrate cages without or with small interactions, finally leading to a relatively high gas uptake.

  18. Influence of limestone on the hydration of Portland cements

    International Nuclear Information System (INIS)

    Lothenbach, Barbara; Le Saout, Gwenn; Gallucci, Emmanuel; Scrivener, Karen

    2008-01-01

    The influence of the presence of limestone on the hydration of Portland cement was investigated. Blending of Portland cement with limestone was found to influence the hydrate assemblage of the hydrated cement. Thermodynamic calculations as well as experimental observations indicated that in the presence of limestone, monocarbonate instead of monosulfate was stable. Thermodynamic modelling showed that the stabilisation of monocarbonate in the presence of limestone indirectly stabilised ettringite leading to a corresponding increase of the total volume of the hydrate phase and a decrease of porosity. The measured difference in porosity between the 'limestone-free' cement, which contained less than 0.3% CO 2 , and a cement containing 4% limestone, however, was much smaller than calculated. Coupling of thermodynamic modelling with a set of kinetic equations which described the dissolution of the clinker, predicted quantitatively the amount of hydrates. The quantities of ettringite, portlandite and amorphous phase as determined by TGA and XRD agreed well with the calculated amounts of these phases after different periods of time. The findings in this paper show that changes in the bulk composition of hydrating cements can be followed by coupled thermodynamic models. Comparison between experimental and modelled data helps to understand in more detail the dominating processes during cement hydration

  19. Characteristics of Methane Hydrate Formation in Artificial and Natural Media

    Directory of Open Access Journals (Sweden)

    Qingbai Wu

    2013-03-01

    Full Text Available The formation of methane hydrate in two significantly different media was investigated, using silica gel as an artificial medium and loess as a natural medium. The methane hydrate formation was observed through the depletion of water in the matrix, measured via the matrix potential and the relationship between the matrix potential and the water content was determined using established equations. The velocity of methane hydrate nucleation slowed over the course of the reaction, as it relied on water transfer to the hydrate surfaces with lower Gibbs free energy after nucleation. Significant differences in the reactions in the two types of media arose from differences in the water retention capacity and lithology of media due to the internal surface area and pore size distributions. Compared with methane hydrate formation in silica gel, the reaction in loess was much slower and formed far less methane hydrate. The results of this study will advance the understanding of how the properties of the environment affect the formation of gas hydrates in nature.

  20. Structural and hydration properties of amorphous tricalcium silicate

    International Nuclear Information System (INIS)

    Mori, K.; Fukunaga, T.; Shiraishi, Y.; Iwase, K.; Xu, Q.; Oishi, K.; Yatsuyanagi, K.; Yonemura, M.; Itoh, K.; Sugiyama, M.; Ishigaki, T.; Kamiyama, T.; Kawai, M.

    2006-01-01

    Mechanical milling was carried out to synthesize amorphous tricalcium silicate (Ca 3 SiO 5 ) sample, where Ca 3 SiO 5 is the most principal component of Portland cement. The partial phase transformation from the crystalline to the amorphous state was observed by X-ray and neutron diffractions. Moreover, it was found that the structural distortion on the Ca-O correlation exists in the milled Ca 3 SiO 5 . The hydration of the milled Ca 3 SiO 5 with D 2 O proceeds as follows: the formation of hydration products such as Ca(OD) 2 rapidly occurs in the early hydration stage, and then proceeds slowly after about 15 h. The induction time for the hydration of the milled Ca 3 SiO 5 is approximately one half shorter than that for the hydration of the unmilled one. This result means that the mechanical milling brings about the chemical activity of Ca 3 SiO 5 for hydration, and may be particularly useful for increasing the reactivity in the early hydration stage

  1. Electrochemical stability of ionic clathrate hydrates and their structural consideration

    International Nuclear Information System (INIS)

    Lee, Wonhee; Lim, Dongwook; Lee, Huen

    2013-01-01

    Although electrochemical stability is an essential factor in relation to the potential applications of ionic clathrate hydrates to solid electrolytes, most studies regarding the proton conductors have focused on their ionic conductivity and thermal stability. Solid electrolytes in various electrochemical devices have to endure the applied potentials; thus, we examined the linear sweep voltammograms of various tetraalkylammonium hydroxide hydrates in order to shed light on the trend of electrochemical stability depending on the hydrate structure. We revealed that the electrochemical stability of Me 4 NOH hydrates is mainly affected by both their ionic concentration and cage occupancy. In particular, the true clathrate structures of β-Me 4 NOH hydrates are more electrochemically stable than their α-forms that possess partially broken hydrogen bonds. We also observed that the binary THF–Pr 4 NOH and pure Bu 4 NOH clathrate hydrates exhibit greater electrochemical stability than those of pure Me 4 NOH hydrates having lower or similar ionic concentrations. These results are considered to arise from the fact that each of the Pr 4 N + and Bu 4 N + ions occupies an extended space comprising four cages, which leads to stabilization of the larger unit, whereas a Me 4 N + ion is completely included only in one cage

  2. Ab initio modelling of methane hydrate thermophysical properties.

    Science.gov (United States)

    Jendi, Z M; Servio, P; Rey, A D

    2016-04-21

    The key thermophysical properties of methane hydrate were determined using ab initio modelling. Using density functional theory, the second-order elastic constants, heat capacity, compressibility, and thermal expansion coefficient were calculated. A wide and relevant range of pressure-temperature conditions were considered, and the structures were assessed for stability using the mean square displacement and radial distribution functions. Methane hydrate was found to be elastically isotropic with a linear dependence of the bulk modulus on pressure. Equally significant, multi-body interactions were found to be important in hydrates, and water-water interactions appear to strongly influence compressibility like in ice Ih. While the heat capacity of hydrate was found to be higher than that of ice, the thermal expansion coefficient was significantly lower, most likely due to the lower rigidity of hydrates. The mean square displacement gave important insight into stability, heat capacity, and elastic moduli, and the radial distribution functions further confirmed stability. The presented results provide a much needed atomistic thermoelastic characterization of methane hydrates and are essential input for the large-scale applications of hydrate detection and production.

  3. Influence of Lithium Carbonate on C3A Hydration

    Directory of Open Access Journals (Sweden)

    Weiwei Han

    2018-01-01

    Full Text Available Lithium salts, known to ameliorate the effects of alkali-silica reaction, can make significant effects on cement setting. However, the mechanism of effects on cement hydration, especially the hydration of C3A which is critical for initial setting time of cement, is rarely reported. In this study, the development of pH value of pore solution, conductivity, thermodynamics, and mineralogical composition during hydration of C3A with or without Li2CO3 are investigated. The results demonstrate that Li2CO3 promotes C3A hydration through high alkalinity, due to higher activity of lithium ion than that of calcium ion in the solution and carbonation of C3A hydration products resulted from Li2CO3. Li2CO3 favors the C3A hydration in C3A-CaSO4·2H2O-Ca(OH2-H2O hydration system and affects the mineralogical variation of the ettringite phase(s.

  4. Hydration behaviors of calcium silicate-based biomaterials.

    Science.gov (United States)

    Lee, Yuan-Ling; Wang, Wen-Hsi; Lin, Feng-Huie; Lin, Chun-Pin

    2017-06-01

    Calcium silicate (CS)-based biomaterials, such as mineral trioxide aggregate (MTA), have become the most popular and convincing material used in restorative endodontic treatments. However, the commercially available CS-based biomaterials all contain different minor additives, which may affect their hydration behaviors and material properties. The purpose of this study was to evaluate the hydration behavior of CS-based biomaterials with/without minor additives. A novel CS-based biomaterial with a simplified composition, without mineral oxides as minor additives, was produced. The characteristics of this biomaterial during hydration were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The hydration behaviors of commercially available gray and white MTAs with mineral oxide as minor additives were also evaluated for reference. For all three test materials, the XRD analysis revealed similar diffraction patterns after hydration, but MTAs presented a significant decrease in the intensities of Bi 2 O 3 -related peaks. SEM results demonstrated similar porous microstructures with some hexagonal and facetted crystals on the outer surfaces. In addition, compared to CS with a simplified composition, the FTIR plot indicated that hydrated MTAs with mineral oxides were better for the polymerization of calcium silicate hydrate (CSH), presenting Si-O band shifting to higher wave numbers, and contained more water crystals within CSH, presenting sharper bands for O-H bending. Mineral oxides might not result in significant changes in the crystal phases or microstructures during the hydration of CS-based biomaterials, but these compounds affected the hydration behavior at the molecular level. Copyright © 2016. Published by Elsevier B.V.

  5. Phase behavior of methane hydrate in silica sand

    International Nuclear Information System (INIS)

    Sun, Shi-Cai; Liu, Chang-Ling; Ye, Yu-Guang; Liu, Yu-Feng

    2014-01-01

    Highlights: • Hydrate p-T trace in coarse-grained sediment is consistent with that in bulk water. • Fine-grained sediment affects hydrate equilibrium for the depressed water activity. • Hydrate equilibrium in sediment is related to the pore size distribution. • The application of hydrate equilibrium in sediment depends on the actual condition. -- Abstract: Two kinds of silica sand powder with different particle size were used to investigate the phase behavior of methane hydrate bearing sediment. In coarse-grained silica sand, the measured temperature and pressure range was (281.1 to 284.2) K and (5.9 to 7.8) MPa, respectively. In fine-grained silica sand, the measured temperature and pressure range was (281.5 to 289.5) K and (7.3 to 16.0) MPa, respectively. The results show that the effect of coarse-grained silica sand on methane hydrate phase equilibrium can be ignored; however, the effect of fine-grained silica sand on methane hydrate phase equilibrium is significant, which is attributed to the depression of water activity caused by the hydrophilicity and negatively charged characteristic of silica particle as well as the pore capillary pressure. Besides, the analysis of experimental results using the Gibbs–Thomson equation shows that methane hydrate phase equilibrium is related to the pore size distribution of silica sand. Consequently, for the correct application of phase equilibrium data of hydrate bearing sediment, the geological condition and engineering requirement should be taken into consideration in gas production, resource evaluation, etc

  6. Argentina to fully privatize state owned YPF

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Argentina's Congress has voted to fully privatize state petroleum company Yacimientos Petroliferos Fiscales (YPF), a move the government expects to net at least $8 billion. Despite some political opposition, the vote was 119-10 in favor, with one abstention and opposition party members refusing to participate in the vote. Argentina's President Carlos Menem had threatened to authorize YPF privatization by decree if there was no quorum for a vote. YPF is responsible for 40% of Argentina's oil production. The country h as been self-sufficient in crude since 1982. Current production is 563,472 b/d, and proved reserves of oil and gas are valued at $7 billion

  7. On the hydration and conformation of cocaine in solution

    Science.gov (United States)

    Gillams, Richard J.; Lorenz, Christian D.; McLain, Sylvia E.

    2017-05-01

    In order to develop theories relating to the mechanism through which cocaine can diffuse across the blood-brain barrier, it is important to understand the interplay between the hydration of the molecule and the adopted conformation. Here key differences in the hydration of cocaine hydrochloride (CHC) and freebase cocaine (CFB) are highlighted on the atomic scale in solution, through the use of molecular dynamics simulations. By adopting different conformations, CHC and CFB experience differing hydration environments. The interplay between these two factors may account for the vast difference in solubility of these two molecules.

  8. Gas hydrate dissociation prolongs acidification of the Anthropocene oceans

    OpenAIRE

    Boudreau, B.P.; Luo, Y.; Meysman, F.J.R.; Middelburg, J

    2015-01-01

    Anthropogenic warming of the oceans can release methane (CH4) currently stored in sediments as gas hydrates. This CH4 will be oxidized to CO2, thus increasing the acidification of the oceans. We employ a biogeochemical model of the multimillennial carbon cycle to determine the evolution of the oceanic dissolved carbonate system over the next 13?kyr in response to CO2 from gas hydrates, combined with a reasonable scenario for long-term anthropogenic CO2 emissions. Hydrate-derived CO2 will appr...

  9. An international effort to compare gas hydrate reservoir simulators

    Energy Technology Data Exchange (ETDEWEB)

    Wilder, J.W. [Akron Univ., Akron, OH (United States). Dept. of Theoretical and Applied Math; Moridis, G.J. [California Univ., Berkely, CA (United States). Earth Sciences Div., Lawrence Berkely National Lab.; Wilson, S.J. [Ryder Scott Co., Denver, CO (United States); Kurihara, M. [Japan Oil Engineering Co. Ltd., Tokyo (Japan); White, M.D. [Pacific Northwest National Laboratory Hydrology Group, Richland, WA (United States); Masuda, Y. [Tokyo Univ., Tokyo (Japan). Dept. of Geosystem Engineering; Anderson, B.J. [National Energy Technology Lab., Morgantown, WV (United States)]|[West Virginia Univ., Morgantown, WV (United States). Dept. of Chemical Engineering; Collett, T.S. [United States Geological Survey, Denver, CO (United States); Hunter, R.B. [ASRC Energy Services, Anchorage, AK (United States); Narita, H. [National Inst. of Advanced Industrial Science and Technology, MEthane hydrate Research Lab., Sapporo (Japan); Pooladi-Darvish, M. [Fekete Associates Inc., Calgary, AB (Canada); Rose, K.; Boswell, R. [National Energy Technology Lab., Morgantown, WV (United States)

    2008-07-01

    In this study, 5 different gas hydrate production scenarios were modeled by the CMG STARS, HydateResSim, MH-21 HYDRES, STOMP-HYD and the TOUGH+HYDRATE reservoir simulators for comparative purposes. The 5 problems ranged in complexity from 1 to 3 dimensional with radial symmetry, and in horizontal dimensions of 20 meters to 1 kilometer. The scenarios included (1) a base case with non-isothermal multi-fluid transition to equilibrium, (2) a base case with gas hydrate (closed-domain hydrate dissociation), (3) dissociation in a 1-D open domain, (4) gas hydrate dissociation in a one-dimensional radial domain, similarity solutions, (5) gas hydrate dissociation in a two-dimensional radial domain. The purpose of the study was to compare the world's leading gas hydrate reservoir simulators in an effort to improve the simulation capability of experimental and naturally occurring gas hydrate accumulations. The problem description and simulation results were presented for each scenario. The results of the first scenario indicated very close agreement among the simulators, suggesting that all address the basics of mass and heat transfer, as well as overall process of gas hydrate dissociation. The third scenario produced the initial divergence among the simulators. Other differences were noted in both scenario 4 and 5, resulting in significant corrections to algorithms within several of the simulators. The authors noted that it is unlikely that these improvements would have been identified without this comparative study due to a lack of real world data for validation purposes. It was concluded that the solution for gas hydrate production involves a combination of highly coupled fluid, heat and mass transport equations combined with the potential for formation or disappearance of multiple solid phases in the system. The physical and chemical properties of the rocks containing the gas hydrate depend on the amount of gas hydrate present in the system. Each modeling and

  10. Hydration numbers of trivalent lanthanide and actinide ions

    International Nuclear Information System (INIS)

    David, F.; Fourest, B.; Duplessis, J.

    1987-01-01

    Investigations on the structure of actinide aquo ions and determination of hydration numbers have to be studied, essentially, through radiochemical methods. They measured the transport numbers, diffusion coefficient D by the open end capillary method and ionic mobility u by electrophoresis. Both methods show a discontinuity in the transport number corresponding to the crystallographic radius of Eu 3+ or Bk 3+ ion. They deduced the volume of the actinide aquo ions, and the coordination number in the primary sphere. From calculations of the electrostriction phenomenon in the vicinity of central ion, they obtained effective volume of the water molecules and the dynamic hydration number corresponding to the second hydration sphere

  11. State of hydration and electrical conductance of ichthyotic skin

    OpenAIRE

    A B Gupta; Manisha Bhattacharya; B Haldar

    1990-01-01

    Dry skin of twelve subjects suffering from ichthyosis vulgaris and the efficacy of a moisturiser-Cotaryl were quantitatively assessed by measuring the skin surface hydration and high frequency (3.5 MHz) electrical conductance of skin. The state of hydration and conductance of ichthyotic skin were 86.9 + 24.6 and 11.0 + 5.7 micro-mho respectively, being much less-compared to 132. 0 + 5.3 and 72.5 + 54.0 micro-mho ofnormal subjects. The moisturiser increased the state of hydration and also the ...

  12. Examination of Hydrate Formation Methods: Trying to Create Representative Samples

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T.J.; Rees, E.V.L.; Nakagawa, S.; Kwon, T.-H.

    2011-04-01

    Forming representative gas hydrate-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 hydrate samples in the laboratory has been done a number of ways, each having advantages and disadvantages. The ice-to-hydrate method [Stern et al., 1996], contacts melting ice with methane at the appropriate pressure to form hydrate. The hydrate can then be crushed and mixed with mineral grains under controlled conditions, and then compacted to create laboratory samples of methane hydrate in a mineral medium. The hydrate 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 hydrate-stable conditions (chilled and pressurized with gas), allowing hydrate to form. This method typically produces grain-cementing hydrate 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 hydrate-stable conditions where hydrate 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 hydrate from more soluble gases such as carbon dioxide. It is thought that this method more closely simulates the way most natural gas hydrate has formed. Laboratory implementation, however, is difficult, and sample formation is prohibitively time consuming [Minagawa et al., 2005; Spangenberg and Kulenkampff, 2005]. In another version of this technique, a specified quantity of gas

  13. Methane hydrate synthesis from ice: Influence of pressurization and ethanol on optimizing formation rates and hydrate yield

    Science.gov (United States)

    Chen, Po-Chun.; Huang, Wuu-Liang; Stern, Laura A.

    2010-01-01

    Polycrystalline methane gas hydrate (MGH) was synthesized using an ice-seeding method to investigate the influence of pressurization and ethanol on the hydrate formation rate and gas yield of the resulting samples. When the reactor is pressurized with CH4 gas without external heating, methane hydrate 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 hydrate rinds around the ice grains. The heat generated by the exothermic reaction of methane hydrate formation buffers the sample temperature near the melting point of ice for enough time to allow for continuous hydrate growth at high rates. Surprisingly, faster rates and higher yields of methane hydrate 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.

  14. Changes in structure and preferential cage occupancy of ethane hydrate and ethane-methane mixed gas hydrate under high pressure

    International Nuclear Information System (INIS)

    Hirai, H; Takahara, N; Kawamura, T; Yamamoto, Y; Yagi, T

    2010-01-01

    Structural changes and preferential cage occupancies were examined for ethane hydrate and ethane-methane mixed gas hydrates with five compositions in a pressure range of 0.2 to 2.8 GPa at room temperature. X-ray diffractometry and Raman spectroscopy showed the following structural changes. The initial structure, structure I (sI), of ethane hydrate was retained up to 2.1 GPa without any structural change. For the mixed hydrates, sI was widely distributed throughout the region examined except for the methane-rich and lower pressure regions, where sII and sH appeared. Above 2.1 GPa ethane hydrate and all of the mixed hydrates decomposed into ice VI and ethane fluid or methane-ethane fluid, respectively. The Raman study revealed that occupation of the small cages by ethane molecules occurred above 0.1 GPa in ethane hydrate and continued up to decomposition at 2.1 GPa, although it was thought that ethane molecules were contained only in the large cage.

  15. Fully 3D GPU PET reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, J.L., E-mail: joaquin@nuclear.fis.ucm.es [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Espana, S. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Cal-Gonzalez, J. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Vaquero, J.J. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Desco, M. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain); Udias, J.M. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain)

    2011-08-21

    Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

  16. Fully 3D GPU PET reconstruction

    International Nuclear Information System (INIS)

    Herraiz, J.L.; Espana, S.; Cal-Gonzalez, J.; Vaquero, J.J.; Desco, M.; Udias, J.M.

    2011-01-01

    Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

  17. Fully populated VCM or the hidden parameter

    Directory of Open Access Journals (Sweden)

    Kermarrec G.

    2017-11-01

    Full Text Available Least-squares estimates are trustworthy with minimal variance if the correct stochastic model is used. Due to computational burden, diagonal models that neglect correlations are preferred to describe the elevation dependency of the variance of GPS observations. In this contribution, an improved stochastic model based on a parametric function to take correlations between GPS phase observations into account is presented. Built on an adapted and flexible Mátern function accounting for spatiotemporal variabilities, its parameters can be fixed thanks to Maximum Likelihood Estimation or chosen apriori to model turbulent tropospheric refractivity fluctuations. In this contribution, we will show in which cases and under which conditions corresponding fully populated variance covariance matrices (VCM replace the estimation of a tropospheric parameter. For this equivalence “augmented functional versus augmented stochastic model” to hold, the VCM should be made sufficiently largewhich corresponds to computing small batches of observations. A case study with observations from a medium baseline of 80 km divided into batches of 600 s shows improvement of up to 100 mm for the 3Drms when fully populated VCM are used compared with an elevation dependent diagonal model. It confirms the strong potential of such matrices to improve the least-squares solution, particularly when ambiguities are let float.

  18. Communication: Fully coherent quantum state hopping

    Energy Technology Data Exchange (ETDEWEB)

    Martens, Craig C., E-mail: cmartens@uci.edu [University of California, Irvine, California 92697-2025 (United States)

    2015-10-14

    In this paper, we describe a new and fully coherent stochastic surface hopping method for simulating mixed quantum-classical systems. We illustrate the approach on the simple but unforgiving problem of quantum evolution of a two-state quantum system in the limit of unperturbed pure state dynamics and for dissipative evolution in the presence of both stationary and nonstationary random environments. We formulate our approach in the Liouville representation and describe the density matrix elements by ensembles of trajectories. Population dynamics are represented by stochastic surface hops for trajectories representing diagonal density matrix elements. These are combined with an unconventional coherent stochastic hopping algorithm for trajectories representing off-diagonal quantum coherences. The latter generalizes the binary (0,1) “probability” of a trajectory to be associated with a given state to allow integers that can be negative or greater than unity in magnitude. Unlike existing surface hopping methods, the dynamics of the ensembles are fully entangled, correctly capturing the coherent and nonlocal structure of quantum mechanics.

  19. Fully CMOS-compatible titanium nitride nanoantennas

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Justin A., E-mail: jabriggs@stanford.edu [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Naik, Gururaj V.; Baum, Brian K.; Dionne, Jennifer A. [Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Petach, Trevor A.; Goldhaber-Gordon, David [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States)

    2016-02-01

    CMOS-compatible fabrication of plasmonic materials and devices will accelerate the development of integrated nanophotonics for information processing applications. Using low-temperature plasma-enhanced atomic layer deposition (PEALD), we develop a recipe for fully CMOS-compatible titanium nitride (TiN) that is plasmonic in the visible and near infrared. Films are grown on silicon, silicon dioxide, and epitaxially on magnesium oxide substrates. By optimizing the plasma exposure per growth cycle during PEALD, carbon and oxygen contamination are reduced, lowering undesirable loss. We use electron beam lithography to pattern TiN nanopillars with varying diameters on silicon in large-area arrays. In the first reported single-particle measurements on plasmonic TiN, we demonstrate size-tunable darkfield scattering spectroscopy in the visible and near infrared regimes. The optical properties of this CMOS-compatible material, combined with its high melting temperature and mechanical durability, comprise a step towards fully CMOS-integrated nanophotonic information processing.

  20. A geometry-based simulation of the hydration of ions and small molecules

    International Nuclear Information System (INIS)

    Plumridge, T.H.

    2001-01-01

    The behaviour of solutes in water is of universal significance, but still not fully understood. This thesis provides details of a new computer simulation technique used to investigate the hydration of ions and small molecules. In contrast to conventional techniques such as molecular dynamics, this is a purely geometric method involving no forcefield or energy terms. Molecules of interest are modelled using crystallographic data to ensure that the structures are accurate. Water molecules are added randomly at any hydrogen bonding site in chains. At each addition the chain is rotated through all available space testing for the possibility of ring formation. The constraints used by the program to decide whether a ring should be conserved, i.e. whether the ring-forming hydrogen bond is viable were derived from a survey of (i) all available ice and clathrate hydrate structures and (ii) the hydrates of small biological molecules from the Cambridge Crystallographic Data Centre. If a ring forms, it is conserved and the process restarted with the addition of another random water. If the chain reaches a certain length and no hydrogen bonding opportunities are detected, the water chain is dissolved, and the process restarted. Using these techniques structure makers such as sulfate will readily allow structured water to form around them leading to large networks, whereas structure breakers such as urea will not allow any water chains to bridge the hydrogen bonding groups. The software has been tested with a set of twenty widely varying solutes and has produced results which generally agree with experimental data for structure makers and breakers, and also agrees well with traditional techniques such as molecular dynamics and Monte Carlo techniques. (author)

  1. Hydrate-Bearing Clayey Sediments: Morphology, Physical Properties, Production and Engineering/Geological Implications

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Sheng [Georgia Tech Research Corporation, Atlanta, GA (United States); Santamarina, J. Carlos [King Abdulaziz Univ., Jeddah (Saudi Arabia)

    2017-12-30

    Fine-grained sediments host more than 90 percent of global gas hydrate accumulation. However, hydrate formation in clay-dominated sediments is less understood and characterized than other types of hydrate occurrence. There is an inadequate understanding of hydrate formation mechanisms, segregation structures, hydrate lens topology, system connectivity, and physical macro-scale properties of clay-dominated hydrate-bearing sediments. This situation hinders further analyses of the global carbon budget as well as engineering challenges/solutions related to hydrate instability and production. This project studies hydrate-bearing clay-dominated sediments with emphasis on the enhanced fundamental understanding of hydrate formation and resulting morphology, the development laboratory techniques to emulate natural hydrate formations, the assessment of analytical tools to predict physical properties, the evaluation of engineering and geological implications, and the advanced understanding of gas production potential from finegrained sediments.

  2. Energy from gas hydrates - assessing the opportunities and challenges for Canada: report of the expert panel on gas hydrates

    International Nuclear Information System (INIS)

    2008-09-01

    Gas hydrates form when water and natural gas combine at low temperatures and high pressures in regions of permafrost and in marine subseafloor sediments. Estimates suggest that the total amount of natural gas bound in hydrate form may exceed all conventional gas resources, or even the amount of all combined hydrocarbon energy. Gas from gas hydrate could provide a potentially vast new source of energy to offset declining supplies of conventional natural gas in North America and to provide greater energy security for countries such as Japan and India that have limited domestic sources. However, complex issues would need to be addressed if gas hydrate were to become a large part of the energy future of Canada. Natural Resources Canada asked the Council of Canadian Academies to assemble a panel of experts to examine the challenges for an acceptable operational extraction of gas hydrates in Canada. This report presented an overview of relevant contextual background, including some basic science; the medium-term outlook for supply and demand in markets for natural gas; broad environmental issues related to gas hydrate in its natural state and as a fuel; and an overview of Canada's contribution to knowledge about gas hydrate in the context of ongoing international research activity. The report also presented current information on the subject and what would be required to delineate and quantify the resource. Techniques for extracting gas from gas hydrate were also outlined. The report also addressed safety issues related to gas hydrate dissociation during drilling operations or release into the atmosphere; the environmental issues associated with potential leakage of methane into the atmosphere and with the large volumes of water produced during gas hydrate dissociation; and jurisdictional and local community issues that would need to be resolved in order to proceed with the commercial exploitation of gas hydrate. It was concluded that there does not appear to be

  3. Fully Printed Flexible and Stretchable Electronics

    Science.gov (United States)

    Zhang, Suoming

    Through this thesis proposal, the author has demonstrated series of flexible or stretchable sensors including strain gauge, pressure sensors, display arrays, thin film transistors and photodetectors fabricated by a direct printing process. By adopting the novel serpentine configuration with conventional non-stretchable materials silver nanoparticles, the fully printed stretchable devices are successfully fabricated on elastomeric substrate with the demonstration of stretchable conductors that can maintain the electrical properties under strain and the strain gauge, which could be used to measure the strain in desired locations and also to monitor individual person's finger motion. And by investigating the intrinsic stretchable materials silver nanowires (AgNWs) with the conventional configuration, the fully printed stretchable conductors are achieved on various substrates including Si, glass, Polyimide, Polydimethylsiloxane (PDMS) and Very High Bond (VHB) tape with the illustration of the capacitive pressure sensor and stretchable electroluminescent displays. In addition, intrinsically stretchable thin-film transistors (TFTs) and integrated logic circuits are directly printed on elastomeric PDMS substrates. The printed devices utilize carbon nanotubes and a type of hybrid gate dielectric comprising PDMS and barium titanate (BaTiO3) nanoparticles. The BaTiO3/PDMS composite simultaneously provides high dielectric constant, superior stretchability, low leakage, as well as good printability and compatibility with the elastomeric substrate. Both TFTs and logic circuits can be stretched beyond 50% strain along either channel length or channel width directions for thousands of cycles while showing no significant degradation in electrical performance. Finally, by applying the SWNTs as the channel layer of the thin film transistor, we successfully fabricate the fully printed flexible photodetector which exhibits good electrical characteristics and the transistors exhibit

  4. Geo-scientific investigations of gas-hydrates in India

    Digital Repository Service at National Institute of Oceanography (India)

    Sain, K.; Gupta, H.; Mazumdar, A.; Bhaumik, A.K.; Bhowmick, P.K.

    The best solution to meet India's overwhelming energy requirement is to tap the nuclear and solar power to the maximum extent possible. Another feasible major energy resource is gas-hydrates (crystalline substances of methane and water) that have...

  5. A Review of the Methane Hydrate Program in Japan

    Directory of Open Access Journals (Sweden)

    Ai Oyama

    2017-09-01

    Full Text Available In this paper, methane hydrate R&D in Japan was examined in the context of Japan’s evolving energy policies. Methane hydrates have been studied extensively in Japanese national R&D programs since 1993, with the goal of utilizing them as an energy resource. Currently, the Research Consortium for Methane Hydrate Resources in Japan (MH 21 is in the third phase of a project that began in early 2002. Based on publicly available reports and other publications, and presentations made at the ten International Workshops for Methane Hydrate Research and Development, we have attempted to provide a timeline and a succinct summary of the major technical accomplishments of MH 21 during project Phases 1, 2, and 3.

  6. Methane Hydrate in Confined Spaces: An Alternative Storage System.

    Science.gov (United States)

    Borchardt, Lars; Casco, Mirian Elizabeth; Silvestre-Albero, Joaquin

    2018-03-14

    Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, as it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physicochemical properties, such as the formation kinetics or pressure and temperature stability, are significantly changed compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structures for methane hydrate formation. We discuss the contribution of advanced characterization techniques and theoretical simulations towards the elucidation of the methane hydrate formation and dissociation process within the confined space. We outline the scientific challenges this system is currently facing and look on possible future applications for this technology. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development of a CB Resistant Durable, Flexible Hydration System

    National Research Council Canada - National Science Library

    Hall, Peyton W; Zeller, Frank T; Bulluck, John W; Dingus, Michael L

    2002-01-01

    A durable, flexible hydration system resistant to contamination by contact with VX, GD, and HD chemical agents, as well as damage by the decontaminants sodium hypochlorite and DS-2 is being developed for aviator use...

  8. Methane hydrates and the future of natural gas

    Science.gov (United States)

    Ruppel, Carolyn

    2011-01-01

    For decades, gas hydrates have been discussed as a potential resource, particularly for countries with limited access to conventional hydrocarbons or a strategic interest in establishing alternative, unconventional gas reserves. Methane has never been produced from gas hydrates at a commercial scale and, barring major changes in the economics of natural gas supply and demand, commercial production at a large scale is considered unlikely to commence within the next 15 years. Given the overall uncertainty still associated with gas hydrates as a potential resource, they have not been included in the EPPA model in MITEI’s Future of Natural Gas report. Still, gas hydrates remain a potentially large methane resource and must necessarily be included in any consideration of the natural gas supply beyond two decades from now.

  9. Research opportunities in salt hydrates for thermal energy storage

    Science.gov (United States)

    Braunstein, J.

    1983-11-01

    The state of the art of salt hydrates as phase change materials for low temperature thermal energy storage is reviewed. Phase equilibria, nucleation behavior and melting kinetics of the commonly used hydrate are summarized. The development of efficient, reliable inexpensive systems based on phase change materials, especially salt hydrates for the storage (and retrieval) of thermal energy for residential heating is outlined. The use of phase change material thermal energy storage systems is not yet widespread. Additional basic research is needed in the areas of crystallization and melting kinetics, prediction of phase behavior in ternary systems, thermal diffusion in salt hydrate systems, and in the physical properties pertinent to nonequilibrium and equilibrium transformations in these systems.

  10. Maximum Recoverable Gas from Hydrate Bearing Sediments by Depressurization

    KAUST Repository

    Terzariol, Marco

    2017-11-13

    The estimation of gas production rates from hydrate bearing sediments requires complex numerical simulations. This manuscript presents a set of simple and robust analytical solutions to estimate the maximum depressurization-driven recoverable gas. These limiting-equilibrium solutions are established when the dissociation front reaches steady state conditions and ceases to expand further. Analytical solutions show the relevance of (1) relative permeabilities between the hydrate free sediment, the hydrate bearing sediment, and the aquitard layers, and (2) the extent of depressurization in terms of the fluid pressures at the well, at the phase boundary, and in the far field. Close form solutions for the size of the produced zone allow for expeditious financial analyses; results highlight the need for innovative production strategies in order to make hydrate accumulations an economically-viable energy resource. Horizontal directional drilling and multi-wellpoint seafloor dewatering installations may lead to advantageous production strategies in shallow seafloor reservoirs.

  11. Positron annihilation probing for the hydratation rate of cement paste

    International Nuclear Information System (INIS)

    Myllylae, R.; Karras, M.

    1975-01-01

    Positron annihilation has been found to be a possible probe for the exponential hydratation of cement paste. Both lifetime and Doppler line broadening measurements revealed the hydratation rate. With the aid of increased stability in the lifetime spectrometer it has been possible to extend the measuring sensitivity over a period of several weeks. Two main lifetimes, tau 1 = 480 +- 20 psec and tau 2 = 2.1 +- 0.1 nsec, were observed to be constant during the hydratation. The intensity of the 2.1 nsec component changed from 4 to 8% after 47 days, and simultaneously the annihilation line narrowed from 2.6 to 2.4 keV. This behaviour has been interpreted as an increase in positronium formation. The possible practical applications of positron annihilation radiation as a hydratation probe has been evaluated for use in a concrete laboratory and even for regular construction work. (orig.) [de

  12. Dissociation behavior of methane gas hydrate in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, C.; Yu-gang, Y.; Chang-ling, L. [Ministry of Land and Resources, Quindao (China). Qingdao Inst. of Marine Geology; Qing-guo, M. [Qingdao Univ. College of Chemical Engineering and Environment, Shandong, Qingdao (China)

    2008-07-01

    Gas hydrates are ice-like compounds that form by natural gas and water and are considered to be a new energy resource. In order to make good use of this resource, it is important to know the hydrate dissociation process. This paper discussed an investigation of methane hydrate dissociation through a simulation experiment. The paper discussed the gas hydrates dissociation experiment including the apparatus and experiment equipment, including methane gas supply; reaction cell; temperature controller; pressure maintainer; and gas flow meter. The paper also presented the method and material including iso-volumetric dissociation and normal pressure dissociation. Last, results and discussion of the results were presented. A comparison of five different particle sizes did not reveal any obvious effects that were related to the porous media, mostly likely because the particle size was too large. 15 refs., 2 tabs., 4 figs.

  13. Infrared spectroscopy for monitoring gas hydrates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, G.T.; Luzinova, Y.; Mizaikoff, B. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Raichlin, Y.; Katzir, A. [Tel-Aviv Univ., Tel-Aviv (Israel). Shool of Physics and Astronomy

    2008-07-01

    This paper introduced the first principles for monitoring gas hydrate formation and dissociation in aqueous solution by evaluating state-responsive infrared (IR) absorption features of water with fiberoptic evanescent field spectroscopy. A first order linear functional relationship was also derived according to Lambert Beer's law in order to quantify the percentage gas hydrate within the volume of water probed via the evanescent field. In addition, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components. As such, evanescent field sensing strategies were established as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments. 21 refs., 5 figs.

  14. Thermal Regeneration of Sulfuric Acid Hydrates after Irradiation

    Science.gov (United States)

    Loeffler, Mark J.; Hudson, Reggie L.

    2012-01-01

    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 hydrates, 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 hydrate's infrared absorptions. This thermal regeneration of the original hydrates was nearly 100% efficient, indicating that over geological times, thermally-induced phase transitions enhanced by temperature fluctuations will reform a large fraction of crystalline hydrated 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.

  15. Maximum Recoverable Gas from Hydrate Bearing Sediments by Depressurization

    KAUST Repository

    Terzariol, Marco; Goldsztein, G.; Santamarina, Carlos

    2017-01-01

    financial analyses; results highlight the need for innovative production strategies in order to make hydrate accumulations an economically-viable energy resource. Horizontal directional drilling and multi-wellpoint seafloor dewatering installations may lead

  16. Skin hydration in nursing home residents using disposable bed baths.

    Science.gov (United States)

    Gillis, Katrin; Tency, Inge; Roelant, Ella; Laureys, Sarina; Devriendt, Hendrik; Lips, Dirk

    2016-01-01

    The objective of this study was to evaluate a new way for applying bed baths and reducing the risk for dry skin by comparing the effect of two washing methods on skin hydration. A cluster randomized trial was conducted. Skin hydration was measured before and after implementation of disposable wash gloves, using a MoistureMeter SC at three skin sites. Total skin hydration did not differ between residents at the start of the study in both groups. After implementation, the post minus pre hydration scores were higher for the intervention group than the control group at all skin sites. However, the difference was only significant at cheek site. The use of disposable wash gloves does not increase the risk for dry skin in comparison with traditional washing methods. These results may encourage the introduction of disposable wash gloves as an innovation in daily skin care practice. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Clinical study on orofacial photonic hydration using phototherapy and biomaterials

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Grandi, Natália D. P.; Florez, Fernando L. E.; Grecco, Clovis; Lopes, Luciana A.

    2015-06-01

    Skin hydration is important to prevent aging and dysfunction of orofacial system. Nowadays, it is known that cutaneous system is linked to muscle system, then every dentist need to treat healthy facial skin, as lips, keeping orofacial functions healthy. Thirty-two patients were treated using laser and led therapy single or associated to biomaterials (dermo-cosmetics) searching for the best protocol to promote skin hydration. Using a peace of equipment to measure electric impedance, percentage of water and oil from skin, before and after different treatments were analyzed. Statistic tests using 5% and 0.1% of significance were applied and results showed that light could improve hydration of epidermis layer of facial skin. Considering just light effect, using infrared laser followed by blue led system is more effective to hydration than just blue led system application. Considering dermo-cosmetic and light, the association between both presented the best result.

  18. Influence of Liquid Paraffin, White Soft Paraffin and Initial Hydration ...

    African Journals Online (AJOL)

    hydrated white soft paraffin on the viscosity of a cream formulated with a corticosteroid. Methods: The formulations were prepared via homogenization with variable velocity in the range 3300 - 4000 rpm. Individual series of preparations contained the ...

  19. A study on dehydration of rare earth chloride hydrate

    International Nuclear Information System (INIS)

    Cho, Yong Zun; Eun, Hee Chul; Son, Sung Mo; Lee, Tae Kyo; Hwang, Taek Sung

    2012-01-01

    The dehydration schemes of rare earth (La, Ce, Nd, Pr, Sm. Eu, Gd, Y) chloride hydrates was investigated by using a dehydration apparatus. To prevent the formation of the rare earth oxychlorides, the operation temperature was changed step by step (80→150→230 degree C) based on the TGA (thermo-gravimetric analysis) results of the rare earth chloride hydrates. A vacuum pump and preheated Ar gas were used to effectively remove the evaporated moisture and maintain an inert condition in the dehydration apparatus. The dehydration temperature of the rare earth chloride hydrate was increased when the atomic number of the rare earth nuclide was increased. The content of the moisture in the rare earth chloride hydrate was decreased below 10% in the dehydration apparatus.

  20. Early hydration cement Effect of admixtures superplasticizers

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2001-06-01

    Full Text Available Early hydration of portland cement with superplasticizer admixtures of different nature has been studied. These admixtures were: one based on melamine synthetic, other based on vinyl copolymer and other based on polyacrylate copolymers. The dosage of the formers were constant (1% weigth of cement and for the third, the influence of admixture dosage was also evaluated, giving dosage values among 1-0.3%. The pastes obtained were studied by conduction calorimetry, XRD and FTIR. Also the apparent fluidity was determined by "Minislump" test. The main results obtained were: a superplasticizers admixtures used, regardless of their nature and for the polycarboxilate one the dosage, retard the silicate hydration (specially, alite phase, b The ettringite formation is affected by the nature of the admixture. cA relationship between the dosage of admixture based on polycarboxilates and the time at the acceleration has been established. A lineal relation (y = 11.03 + 16.05x was obtained. From these results is possible to know, in function of dosage admixture, the time when the masive hydration products and the setting times are produced. Also the total heat releases in these reactions is independent of the nature and dosage of admixture, saying that in all cases the reactions are the same.

    En el presente trabajo se ha estudiado la hidratación inicial de un cemento portland aditivado con superplastificantes de diferente naturaleza. Dichos aditivos fueron: uno basado en melaminas sintéticas, otro en copolímeros vinilicos y otro en policarboxilatos. La dosificación de los dos primeros se fijó constante en 1% en peso con relación al cemento, mientras que para el tercero se evaluó, también, la influencia de la dosificación, tomando proporciones desde el 1% hasta el 0,3%. Las pastas obtenidas se estudiaron por: calorimetría de conducción, DRX y FTIR. También se determinó la fluidez de la pasta a través del ensayo del "Minislump ". Los

  1. Effect of skin hydration on the dynamics of fingertip gripping contact.

    Science.gov (United States)

    André, T; Lévesque, V; Hayward, V; Lefèvre, P; Thonnard, J-L

    2011-11-07

    The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

  2. Report: Fourth International Conference on Gas Hydrates, held at Yokohama, Japan, 19-23 May 2002

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.

    formations, while Dr. L. Stern presented ne insights into the phenomena of anomalous or self- preservation of gas hydrates. JOUR.GEOL.SOC.INDIA, VOL.61, JAN. 2001 Posters on hydrate formation and prevention in pipelines and hydrate based...-1 REPORT ON THE 4TH INTERNATIONAL CONFERENCE ON GAS HYDRATES The fourth International Conference on Gas Hydrates was recently held at Yokohama, Japan, between 19-23 May 2002 following the earlier conferences held in USA (1993...

  3. A Fully Automated Penumbra Segmentation Tool

    DEFF Research Database (Denmark)

    Nagenthiraja, Kartheeban; Ribe, Lars Riisgaard; Hougaard, Kristina Dupont

    2012-01-01

    Introduction: Perfusion- and diffusion weighted MRI (PWI/DWI) is widely used to select patients who are likely to benefit from recanalization therapy. The visual identification of PWI-DWI-mismatch tissue depends strongly on the observer, prompting a need for software, which estimates potentially...... salavageable tissue, quickly and accurately. We present a fully Automated Penumbra Segmentation (APS) algorithm using PWI and DWI images. We compare automatically generated PWI-DWI mismatch mask to mask outlined manually by experts, in 168 patients. Method: The algorithm initially identifies PWI lesions......) at 600∙10-6 mm2/sec. Due to the nature of thresholding, the ADC mask overestimates the DWI lesion volume and consequently we initialized level-set algorithm on DWI image with ADC mask as prior knowledge. Combining the PWI and inverted DWI mask then yield the PWI-DWI mismatch mask. Four expert raters...

  4. Simulations of fully deformed oscillating flux tubes

    Science.gov (United States)

    Karampelas, K.; Van Doorsselaere, T.

    2018-02-01

    Context. In recent years, a number of numerical studies have been focusing on the significance of the Kelvin-Helmholtz instability in the dynamics of oscillating coronal loops. This process enhances the transfer of energy into smaller scales, and has been connected with heating of coronal loops, when dissipation mechanisms, such as resistivity, are considered. However, the turbulent layer is expected near the outer regions of the loops. Therefore, the effects of wave heating are expected to be confined to the loop's external layers, leaving their denser inner parts without a heating mechanism. Aim. In the current work we aim to study the spatial evolution of wave heating effects from a footpoint driven standing kink wave in a coronal loop. Methods: Using the MPI-AMRVAC code, we performed ideal, three dimensional magnetohydrodynamic simulations of footpoint driven transverse oscillations of a cold, straight coronal flux tube, embedded in a hotter environment. We have also constructed forward models for our simulation using the FoMo code. Results: The developed transverse wave induced Kelvin-Helmholtz (TWIKH) rolls expand throughout the tube cross-section, and cover it entirely. This turbulence significantly alters the initial density profile, leading to a fully deformed cross section. As a consequence, the resistive and viscous heating rate both increase over the entire loop cross section. The resistive heating rate takes its maximum values near the footpoints, while the viscous heating rate at the apex. Conclusions: We conclude that even a monoperiodic driver can spread wave heating over the whole loop cross section, potentially providing a heating source in the inner loop region. Despite the loop's fully deformed structure, forward modelling still shows the structure appearing as a loop. A movie attached to Fig. 1 is available at http://https://www.aanda.org

  5. Lidar Cloud Detection with Fully Convolutional Networks

    Science.gov (United States)

    Cromwell, E.; Flynn, D.

    2017-12-01

    The vertical distribution of clouds from active remote sensing instrumentation is a widely used data product from global atmospheric measuring sites. The presence of clouds can be expressed as a binary cloud mask and is a primary input for climate modeling efforts and cloud formation studies. Current cloud detection algorithms producing these masks do not accurately identify the cloud boundaries and tend to oversample or over-represent the cloud. This translates as uncertainty for assessing the radiative impact of clouds and tracking changes in cloud climatologies. The Atmospheric Radiation Measurement (ARM) program has over 20 years of micro-pulse lidar (MPL) and High Spectral Resolution Lidar (HSRL) instrument data and companion automated cloud mask product at the mid-latitude Southern Great Plains (SGP) and the polar North Slope of Alaska (NSA) atmospheric observatory. Using this data, we train a fully convolutional network (FCN) with semi-supervised learning to segment lidar imagery into geometric time-height cloud locations for the SGP site and MPL instrument. We then use transfer learning to train a FCN for (1) the MPL instrument at the NSA site and (2) for the HSRL. In our semi-supervised approach, we pre-train the classification layers of the FCN with weakly labeled lidar data. Then, we facilitate end-to-end unsupervised pre-training and transition to fully supervised learning with ground truth labeled data. Our goal is to improve the cloud mask accuracy and precision for the MPL instrument to 95% and 80%, respectively, compared to the current cloud mask algorithms of 89% and 50%. For the transfer learning based FCN for the HSRL instrument, our goal is to achieve a cloud mask accuracy of 90% and a precision of 80%.

  6. A novel fully integrated handheld gamma camera

    International Nuclear Information System (INIS)

    Massari, R.; Ucci, A.; Campisi, C.; Scopinaro, F.; Soluri, A.

    2016-01-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  7. A novel fully integrated handheld gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Massari, R.; Ucci, A.; Campisi, C. [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy); Scopinaro, F. [University of Rome “La Sapienza”, S. Andrea Hospital, Rome (Italy); Soluri, A., E-mail: alessandro.soluri@ibb.cnr.it [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy)

    2016-10-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  8. HEC influence on cement hydration measured by conductometry

    OpenAIRE

    Pourchez , Jérémie; Grosseau , Philippe; Guyonnet , René; Ruot , Bertrand

    2006-01-01

    International audience; Cellulose ethers are of universal use in factory-made mortars, though their influences on mortar properties at a molecular scale are poorly understood. Recent studies dealt with the influence of hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) molecular parameters on cement hydration. It was concluded that the degree of substitution is the most relevant factor on cement hydration kinetics, contrary to the molecular weight. Nevertheless, the ...

  9. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting...... comparative studies. This chapter presents a short historical overview about these fluorescent reporters, discusses on different models proposed to explain their sensitivity to membrane hydration, and includes relevant examples from experiments performed in artificial and biological membranes....

  10. Zirconium molybdate hydrate precipitates in spent nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    Magnaldo, A.; Noire, M.H.; Esbelin, E.; Dancausse, J.P.; Picart, S.

    2004-01-01

    This paper presents through 2 posters a general overview studies realised by CEA teams on deposits observed in the La Hague plant dissolution facilities. Their main constituents are metallic debris bound together with zirconium molybdate hydrate. A comprehensive study of zirconium molybdate hydrate formation included nucleation and growth kinetics was developed. Fouling mechanisms were consequently explained as influenced by the operation conditions. Pu insertion was also overviewed. Its behaviour is important when curative and preventive chemical treatments are considered. (authors)

  11. Transport of hydrate slurry at high water cut

    OpenAIRE

    Melchuna , Aline; Cameirão , Ana; Herri , Jean-Michel; Ouabbas , Yamina; Glenat , Philippe

    2014-01-01

    Poster; International audience; Oil transportation in pipelines at the end of field production life implies to flow high quantities of water which represents the dominant phase. The process of crystallization of gas hydrates in this system needs to be studied and compared to the opposite one widely studied in the literature where water is the dispersed phase. The laboratory is equipped with the Archimede flow loop where the hydrate crystallization and transport are monitored. The flow loop is...

  12. Formation of nitric acid hydrates - A chemical equilibrium approach

    Science.gov (United States)

    Smith, Roland H.

    1990-01-01

    Published data are used to calculate equilibrium constants for reactions of the formation of nitric acid hydrates over the temperature range 190 to 205 K. Standard enthalpies of formation and standard entropies are calculated for the tri- and mono-hydrates. These are shown to be in reasonable agreement with earlier calorimetric measurements. The formation of nitric acid trihydrate in the polar stratosphere is discussed in terms of these equilibrium constants.

  13. Life Origination Hydrate Theory (LOH-Theory) and Mitosis and Replication Hydrate Theory (MRH-Theory): three-dimensional PC validation

    Science.gov (United States)

    Kadyshevich, E. A.; Dzyabchenko, A. V.; Ostrovskii, V. E.

    2014-04-01

    Size compatibility of the CH4-hydrate structure II and multi-component DNA fragments is confirmed by three-dimensional simulation; it is validation of the Life Origination Hydrate Theory (LOH-Theory).

  14. Gas Hydrate-Sediment Morphologies Revealed by Pressure Core Analysis

    Science.gov (United States)

    Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M.

    2006-12-01

    Analysis of HYACINTH pressure cores collected on IODP Expedition 311 and NGHP Expedition 1 showed gas hydrate layers, lenses, and veins contained in fine-grained sediments as well as gas hydrate contained in coarse-grained layers. Pressure cores were recovered from sediments on the Cascadia Margin off the North American West Coast and in the Krishna-Godavari Basin in the Western Bay of Bengal in water depths of 800- 1400 meters. Recovered cores were transferred to laboratory chambers without loss of pressure and nondestructive measurements were made at in situ pressures and controlled temperatures. Gamma density, P-wave velocity, and X-ray images showed evidence of grain-displacing and pore-filling gas hydrate in the cores. Data highlights include X-ray images of fine-grained sediment cores showing wispy subvertical veins of gas hydrate and P-wave velocity excursions corresponding to grain-displacing layers and pore-filling layers of gas hydrate. Most cores were subjected to controlled depressurization experiments, where expelled gas was collected, analyzed for composition, and used to calculate gas hydrate saturation within the core. Selected cores were stored under pressure for postcruise analysis and subsampling.

  15. Gas hydrates: entrance to a methane age or climate threat?

    International Nuclear Information System (INIS)

    Krey, Volker; Nakicenovic, Nebojsa; Grubler, Arnulf; O'Neill, Brian; Riahi, Keywan; Canadell, Josep G; Abe, Yuichi; Andruleit, Harald; Archer, David; Hamilton, Neil T M; Johnson, Arthur; Kostov, Veselin; Lamarque, Jean-Francois; Langhorne, Nicholas; Nisbet, Euan G; Riedel, Michael; Wang Weihua; Yakushev, Vladimir

    2009-01-01

    Methane hydrates, ice-like compounds in which methane is held in crystalline cages formed by water molecules, are widespread in areas of permafrost such as the Arctic and in sediments on the continental margins. They are a potentially vast fossil fuel energy source but, at the same time, could be destabilized by changing pressure-temperature conditions due to climate change, potentially leading to strong positive carbon-climate feedbacks. To enhance our understanding of both the vulnerability of and the opportunity provided by methane hydrates, it is necessary (i) to conduct basic research that improves the highly uncertain estimates of hydrate occurrences and their response to changing environmental conditions, and (ii) to integrate the agendas of energy security and climate change which can provide an opportunity for methane hydrates-in particular if combined with carbon capture and storage-to be used as a 'bridge fuel' between carbon-intensive fossil energies and zero-emission energies. Taken one step further, exploitation of dissociating methane hydrates could even mitigate against escape of methane to the atmosphere. Despite these opportunities, so far, methane hydrates have been largely absent from energy and climate discussions, including global hydrocarbon assessments and the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

  16. Microstructure of hydrated cement pastes as determined by SANS

    International Nuclear Information System (INIS)

    Sabine, T.; Bertram, W.; Aldridge, L.

    1999-01-01

    Full text: Technologists have known how to make concrete for over 2000 years but despite painstaking research no one has been able to show how and why concrete sets. Part of the problem is that the calcium silicate hydrate (the gel produced by hydrating cement) is amorphous and cannot be characterised by x-ray crystallographic techniques. Small angle neutron scattering on instrument V12a at BENSC was used to characterise the hydration reactions and show the growth of the calcium silicate hydrates during initial hydration and the substantial differences in the rate of growth and structure as different additives are used. SANS spectra were measured as a function of the hydration from three different types of cement paste: 1) Ordinary Portland Cement made with a water to cement ratio of about 0.4; 2) A blend of Ordinary Portland Cement(25%) and Ground Granulated Blast Furnace Slag (75%) with a water to cement ration of about 0.4; 3) A dense paste made from silica fume(24%), Ordinary Portland Cement (76%) at a water to powder ratio of 0.18. The differences in the spectra are interpreted in terms of differences between the microstructure of the pastes

  17. Gas hydrates in the Ulleung Basin, East Sea of Korea

    Directory of Open Access Journals (Sweden)

    Byong-Jae Ryu Michael Riedel

    2017-01-01

    Full Text Available To develop gas hydrates as a potential energy source, geophysical surveys and geological studies of gas hydrates in the Ulleung Basin, East Sea off the east coast of Korea have been carried out since 1997. Bottom-simulating reflector (BSR, initially used indicator for the potential presence of gas hydrates was first identified on seismic data acquired in 1998. Based on the early results of preliminary R&D project, 12367 km of 2D multichannel reflection seismic lines, 38 piston cores, and multi-beam echo-sounder data were collected from 2000 to 2004. The cores showed high amounts of total organic carbon and high residual hydrocarbon gas levels. Gas composition and isotope ratios define it as of primarily biogenic origin. In addition to the BSRs that are widespread across the basin, numerous chimney structures were found in seismic data. These features indicate a high potential of the Ulleung Basin to host significant amounts of gas hydrate. Dedicated geophysical surveys, geological and experimental studies were carried out culminating in two deep drilling expeditions, completed in 2007 and 2010. Sediment coring (including pressure coring, and a comprehensive well log program complements the regional studies and were used for a resource assessment. Two targets for a future test-production are currently proposed: pore-filling gas hydrate in sand-dominated sediments and massive occurrences of gas hydrate within chimney-like structures. An environmental impact study has been launched to evaluate any potential risks to production.

  18. Hydration Control of the Mechanical and Dynamical Properties of Cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Petridis, Loukas; O’Neill, Hugh M.; Johnsen, Mariah [Ripon College, Ripon, Wisconsin 54971, United States; Fan, Bingxin [Department; Schulz, Roland [Department; Mamontov, Eugene; Maranas, Janna [Department; Langan, Paul [Department; Smith, Jeremy C. [Department

    2014-10-13

    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 hydrated state, and it is therefore important to understand how hydration influences its dynamics and mechanics. Here, the nanosecond-time scale dynamics of cellulose is characterized using dynamic neutron scattering experiments and molecular dynamics (MD) simulation. The experiments reveal that hydrated 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 hydration 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% hydrated 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 hydration-dependent increased fluctuations and hydroxymethyl disorder at the cellulose surface lead to enhancement of the rigidity of this important biomolecule.

  19. Exergy analysis of a gas-hydrate cool storage system

    International Nuclear Information System (INIS)

    Bi, Yuehong; Liu, Xiao; Jiang, Minghe

    2014-01-01

    Based on exergy analysis of charging and discharging processes in a gas-hydrate cool storage system, the formulas for exergy efficiency at the sensible heat transfer stage and the phase change stage corresponding to gas-hydrate charging and discharging processes are obtained. Furthermore, the overall exergy efficiency expressions of charging, discharging processes and the thermodynamic cycle of the gas-hydrate cool storage system are obtained. By using the above expressions, the effects of number of transfer units, the inlet temperatures of the cooling medium and the heating medium on exergy efficiencies of the gas-hydrate cool storage system are emphatically analyzed. The research results can be directly used to evaluate the performance of gas-hydrate cool storage systems and design more efficient energy systems by reducing the sources of inefficiency in gas-hydrate cool storage systems. - Highlights: • Formulas for exergy efficiency at four stages are obtained. • Exergy efficiency expressions of two processes and one cycle are obtained. • Three mainly influencing factors on exergy efficiencies are analyzed. • With increasing the inlet temperature of cooling medium, exergy efficiency increases. • With decreasing the inlet temperature of heating medium, exergy efficiency increases

  20. Quinolinium 8-hy-droxy-7-iodo-quinoline-5-sulfonate 0.8-hydrate.

    Science.gov (United States)

    Smith, Graham

    2012-12-01

    In the crystal structure of the title hydrated quinolinium salt of ferron (8-hy-droxy-7-iodo-quinoline-5-sulfonic acid), C9H7N(+)·C9H5INO4S(-)·0.8H2O, the quinolinium cation is fully disordered over two sites (occupancy factors fixed at 0.63 and 0.37) lying essentially within a common plane and with the ferron anions forming π-π-associated stacks down the b axis [minimum ring centroid separation = 3.462 (6) Å]. The cations and anions are linked into chains extending along c through hy-droxy O-H⋯O and quinolinium N-H⋯O hydrogen bonds to sulfonate O-atom acceptors which are also involved in water O-H⋯O hydrogen-bonding inter-actions along b, giving a two-dimensional network.

  1. Quinolinium 8-hydroxy-7-iodoquinoline-5-sulfonate 0.8-hydrate

    Directory of Open Access Journals (Sweden)

    Graham Smith

    2012-12-01

    Full Text Available In the crystal structure of the title hydrated quinolinium salt of ferron (8-hydroxy-7-iodoquinoline-5-sulfonic acid, C9H7N+·C9H5INO4S−·0.8H2O, the quinolinium cation is fully disordered over two sites (occupancy factors fixed at 0.63 and 0.37 lying essentially within a common plane and with the ferron anions forming π–π-associated stacks down the b axis [minimum ring centroid separation = 3.462 (6 Å]. The cations and anions are linked into chains extending along c through hydroxy O—H...O and quinolinium N—H...O hydrogen bonds to sulfonate O-atom acceptors which are also involved in water O—H...O hydrogen-bonding interactions along b, giving a two-dimensional network.

  2. Water Intake and Hydration Indices in Healthy European Adults: The European Hydration Research Study (EHRS).

    Science.gov (United States)

    Malisova, Olga; Athanasatou, Adelais; Pepa, Alex; Husemann, Marlien; Domnik, Kirsten; Braun, Hans; Mora-Rodriguez, Ricardo; Ortega, Juan F; Fernandez-Elias, Valentin E; Kapsokefalou, Maria

    2016-04-06

    Hydration status is linked with health, wellness, and performance. We evaluated hydration status, water intake, and urine output for seven consecutive days in healthy adults. Volunteers living in Spain, Germany, or Greece (n = 573, 39 ± 12 years (51.1% males), 25.0 ± 4.6 kg/m² BMI) participated in an eight-day study protocol. Total water intake was estimated from seven-day food and drink diaries. Hydration status was measured in urine samples collected over 24 h for seven days and in blood samples collected in fasting state on the mornings of days 1 and 8. Total daily water intake was 2.75 ± 1.01 L, water from beverages 2.10 ± 0.91 L, water from foods 0.66 ± 0.29 L. Urine parameters were: 24 h volume 1.65 ± 0.70 L, 24 h osmolality 631 ± 221 mOsmol/kg Η2Ο, 24 h specific gravity 1.017 ± 0.005, 24 h excretion of sodium 166.9 ± 54.7 mEq, 24 h excretion of potassium 72.4 ± 24.6 mEq, color chart 4.2 ± 1.4. Predictors for urine osmolality were age, country, gender, and BMI. Blood indices were: haemoglobin concentration 14.7 ± 1.7 g/dL, hematocrit 43% ± 4% and serum osmolality 294 ± 9 mOsmol/kg Η2Ο. Daily water intake was higher in summer (2.8 ± 1.02 L) than in winter (2.6 ± 0.98 L) (p = 0.019). Water intake was associated negatively with urine specific gravity, urine color, and urine sodium and potassium concentrations (p < 0.01). Applying urine osmolality cut-offs, approximately 60% of participants were euhydrated and 20% hyperhydrated or dehydrated. Most participants were euhydrated, but a substantial number of people (40%) deviated from a normal hydration level.

  3. CO2 injection into submarine, CH4-hydrate bearing sediments: Parameter studies towards the development of a hydrate conversion technology

    Science.gov (United States)

    Deusner, Christian; Bigalke, Nikolaus; Kossel, Elke; Haeckel, Matthias

    2013-04-01

    In the recent past, international research efforts towards exploitation of submarine and permafrost hydrate reservoirs have increased substantially. Until now, findings indicate that a combination of different technical means such as depressurization, thermal stimulation and chemical activation is the most promising approach for producing gas from natural hydrates. Moreover, emission neutral exploitation of CH4-hydrates could potentially be achieved in a combined process with CO2 injection and storage as CO2-hydrate. In the German gas hydrate initiative SUGAR, a combination of experimental and numerical studies is used to elucidate the process mechanisms and technical parameters on different scales. Experiments were carried out in the novel high-pressure flow-through system NESSI (Natural Environment Simulator for sub-Seafloor Interactions). Recent findings suggest that the injection of heated, supercritical CO2 is beneficial for both CH4 production and CO2 retention. Among the parameters tested so far are the CO2 injection regime (alternating vs. continuous injection) and the reservoir pressure / temperature conditions. Currently, the influence of CO2 injection temperature is investigated. It was shown that CH4 production is optimal at intermediate reservoir temperatures (8 ° C) compared to lower (2 ° C) and higher temperatures (10 ° C). The reservoir pressure, however, was of minor importance for the production efficiency. At 8 ° C, where CH4- and CO2-hydrates are thermodynamically stable, CO2-hydrate formation appears to be slow. Eventual clogging of fluid conduits due to CO2-rich hydrate formation force open new conduits, thereby tapping different regions inside the CH4-hydrate sample volume for CH4gas. In contrast, at 2 ° C immediate formation of CO2-hydrate results in rapid and irreversible obstruction of the entire pore space. At 10 ° C pure CO2-hydrates can no longer be formed. Consequently the injected CO2 flows through quickly and interaction with

  4. DNA hydration studied by neutron fiber diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.

  5. Infrared spectroscopy of anionic hydrated fluorobenzenes

    International Nuclear Information System (INIS)

    Schneider, Holger; Vogelhuber, Kristen M.; Weber, J. Mathias

    2007-01-01

    We investigate the structural motifs of anionic hydrated fluorobenzenes by infrared photodissociation spectroscopy and density functional theory. Our calculations show that all fluorobenzene anions under investigation are strongly distorted from the neutral planar molecular geometries. In the anions, different F atoms are no longer equivalent, providing structurally different binding sites for water molecules and giving rise to a multitude of low-lying isomers. The absorption bands for hexa- and pentafluorobenzene show that only one isomer for the respective monohydrate complexes is populated in our experiment. For C 6 F 6 - ·H 2 O, we can assign these bands to an isomer where water forms a weak double ionic hydrogen bond with two F atoms in the ion, in accord with the results of Bowen et al. [J. Chem. Phys. 127, 014312 (2007), following paper.] The spectroscopic motif of the binary complexes changes slightly with decreasing fluorination of the aromatic anion. For dihydrated hexafluorobenzene anions, several isomers are populated in our experiments, some of which may be due to hydrogen bonding between water molecules

  6. Effect of cations on the hydrated proton.

    Science.gov (United States)

    Ottosson, Niklas; Hunger, Johannes; Bakker, Huib J

    2014-09-17

    We report on a strong nonadditive effect of protons and other cations on the structural dynamics of liquid water, which is revealed using dielectric relaxation spectroscopy in the frequency range of 1-50 GHz. For pure acid solutions, protons are known to have a strong structuring effect on water, leading to a pronounced decrease of the dielectric response. We observe that this structuring is reduced when protons are cosolvated with salts. This reduction is exclusively observed for combinations of protons with other ions; for all studied solutions of cosolvated salts, the effect on the structural dynamics of water is observed to be purely additive, even up to high concentrations. We derive an empirical model that quantitatively describes the nonadditive effect of cosolvated protons and cations. We argue that the effect can be explained from the special character of the proton in water and that Coulomb fields exerted by other cations, in particular doubly charged cations like Mg(2+)aq and Ca(2+)aq, induce a localization of the H(+)aq hydration structures.

  7. Mechanism and kinetics of hydrated electron diffusion

    International Nuclear Information System (INIS)

    Tay, Kafui A.; Coudert, Francois-Xavier; Boutin, Anne

    2008-01-01

    Molecular dynamics simulations are used to study the mechanism and kinetics of hydrated electron diffusion. The electron center of mass is found to exhibit Brownian-type behavior with a diffusion coefficient considerably greater than that of the solvent. As previously postulated by both experimental and theoretical works, the instantaneous response of the electron to the librational motions of surrounding water molecules constitutes the principal mode of motion. The diffusive mechanism can be understood within the traditional framework of transfer diffusion processes, where the diffusive step is akin to the exchange of an extramolecular electron between neighboring water molecules. This is a second-order process with a computed rate constant of 5.0 ps -1 at 298 K. In agreement with experiment the electron diffusion exhibits Arrhenius behavior over the temperature range of 298-400 K. We compute an activation energy of 8.9 kJ mol -1 . Through analysis of Arrhenius plots and the application of a simple random walk model it is demonstrated that the computed rate constant for exchange of an excess electron is indeed the phenomenological rate constant associated with the diffusive process

  8. Hydration benefits to courtship feeding in crickets

    Science.gov (United States)

    Ivy, T. M.; Johnson, J. C.; Sakaluk, S. K.

    1999-01-01

    The spermatophore transferred by male decorated crickets (Gryllodes sigillatus) at mating includes a large gelatinous spermatophylax that the female consumes after copulation. Although previous studies have shown that G. sigillatus females gain no nutritional benefits from consuming food gifts, there may be other benefits to their consumption. We examined potential hydration benefits to females by experimentally manipulating both the availability of water and the number of food gifts that females consumed, and by measuring their effect on female fitness. Analysis of the number of nymphs produced by females revealed a significant interaction between the number of spermatophylaxes consumed and water availability. When spermatophylaxes were not provided, females given water ad libitum produced significantly more nymphs than females subjected to water stress. Female longevity was significantly affected by water availability, with an increase in the availability of water corresponding to a significant increase in female longevity. These data suggest that female G. sigillatus accrue fitness benefits by consuming spermatophylaxes when alternative sources of water are unavailable. In addition, females appear to allocate water contained in spermatophylaxes towards reproduction as opposed to survival.

  9. DNA hydration studied by neutron fiber diffraction

    International Nuclear Information System (INIS)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J.

    1994-01-01

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix

  10. Extensin network formation in Vitis vinifera callus cells is an essential and causal event in rapid and H2O2-induced reduction in primary cell wall hydration

    Science.gov (United States)

    2011-01-01

    Background Extensin deposition is considered important for the correct assembly and biophysical properties of primary cell walls, with consequences to plant resistance to pathogens, tissue morphology, cell adhesion and extension growth. However, evidence for a direct and causal role for the extensin network formation in changes to cell wall properties has been lacking. Results Hydrogen peroxide treatment of grapevine (Vitis vinifera cv. Touriga) callus cell walls was seen to induce a marked reduction in their hydration and thickness. An analysis of matrix proteins demonstrated this occurs with the insolubilisation of an abundant protein, GvP1, which displays a primary structure and post-translational modifications typical of dicotyledon extensins. The hydration of callus cell walls free from saline-soluble proteins did not change in response to H2O2, but fully regained this capacity after addition of extensin-rich saline extracts. To assay the specific contribution of GvP1 cross-linking and other wall matrix proteins to the reduction in hydration, GvP1 levels in cell walls were manipulated in vitro by binding selected fractions of extracellular proteins and their effect on wall hydration during H2O2 incubation assayed. Conclusions This approach allowed us to conclude that a peroxidase-mediated formation of a covalently linked network of GvP1 is essential and causal in the reduction of grapevine callus wall hydration in response to H2O2. Importantly, this approach also indicated that extensin network effects on hydration was only partially irreversible and remained sensitive to changes in matrix charge. We discuss this mechanism and the importance of these changes to primary wall properties in the light of extensin distribution in dicotyledons. PMID:21672244

  11. Engineering aspects of a fully mirrored endoscope

    International Nuclear Information System (INIS)

    Terra, A.; Huber, A.; Schweer, B.; Mertens, Ph.; Arnoux, G.; Balshaw, N.; Brezinsek, S.; Egner, S.; Hartl, M.; Kampf, D.; Klammer, J.; Lambertz, H.T.; Morlock, C.; Murari, A.; Reindl, M.; Sanders, S.; Sergienko, G.; Spencer, G.

    2013-01-01

    Highlights: ► Replacement of JET diagnostics to match the new ITER-like Wall. ► The endoscope test ITER-like design with only mirror based optics. ► Withstanding and diagnostic capability during Plasma operation and disruptions. ► Engineering process from design to installation and procurement. -- Abstract: The development of optical diagnostics, like endoscopes, compatible with the ITER environment (metallic plasma facing components, neutron proof optics, etc.) is a challenge, but current tokamaks such as JET provide opportunities to test fully working concepts. This paper describes the engineering aspects of a fully mirrored endoscope that has recently been designed, procured and installed on JET. The system must operate in a very strict environment with high temperature, high magnetic fields up to B = 4 T and rapid field variations (∂B/∂t ∼ 100 T/s) that induce high stresses due to eddy currents in the front mirror assembly. It must be designed to withstand high mechanical loads especially during disruptions, which lead to acceleration of about 7 g at 14 Hz. For the JET endoscope, when the plasma thermal loading, direct and indirect, was added to the assumed disruption loads, the reserve factor, defined as a ratio of yield strength over summed up von Mises stresses, was close to 1 for the mirror components. To ensure reliable operation, several analyses were performed to evaluate the thermo-mechanical performance of the endoscope and a final validation was obtained from mechanical and thermal tests, before the system's final installation in May 2011. During the tests, stability of the field of view angle variation was kept below 1° despite the high thermal gradient on endoscope head (∂T/∂x ∼ 500 K/m). In parallel, to ensure long time operation and to prevent undesirable performance degradation, a shutter system was also implemented in order to reduce impurity deposition on in-vessel mirrors but also to allow in situ transmission calibration

  12. Fully 3D refraction correction dosimetry system

    International Nuclear Information System (INIS)

    Manjappa, Rakesh; Makki, S Sharath; Kanhirodan, Rajan; Kumar, Rajesh; Vasu, Ram Mohan

    2016-01-01

    The irradiation of selective regions in a polymer gel dosimeter results in an increase in optical density and refractive index (RI) at those regions. An optical tomography-based dosimeter depends on rayline path through the dosimeter to estimate and reconstruct the dose distribution. The refraction of light passing through a dose region results in artefacts in the reconstructed images. These refraction errors are dependant on the scanning geometry and collection optics. We developed a fully 3D image reconstruction algorithm, algebraic reconstruction technique-refraction correction (ART-rc) that corrects for the refractive index mismatches present in a gel dosimeter scanner not only at the boundary, but also for any rayline refraction due to multiple dose regions inside the dosimeter. In this study, simulation and experimental studies have been carried out to reconstruct a 3D dose volume using 2D CCD measurements taken for various views. The study also focuses on the effectiveness of using different refractive-index matching media surrounding the gel dosimeter. Since the optical density is assumed to be low for a dosimeter, the filtered backprojection is routinely used for reconstruction. We carry out the reconstructions using conventional algebraic reconstruction (ART) and refractive index corrected ART (ART-rc) algorithms. The reconstructions based on FDK algorithm for cone-beam tomography has also been carried out for comparison. Line scanners and point detectors, are used to obtain reconstructions plane by plane. The rays passing through dose region with a RI mismatch does not reach the detector in the same plane depending on the angle of incidence and RI. In the fully 3D scanning setup using 2D array detectors, light rays that undergo refraction are still collected and hence can still be accounted for in the reconstruction algorithm. It is found that, for the central region of the dosimeter, the usable radius using ART-rc algorithm with water as RI matched

  13. Fully 3D refraction correction dosimetry system.

    Science.gov (United States)

    Manjappa, Rakesh; Makki, S Sharath; Kumar, Rajesh; Vasu, Ram Mohan; Kanhirodan, Rajan

    2016-02-21

    The irradiation of selective regions in a polymer gel dosimeter results in an increase in optical density and refractive index (RI) at those regions. An optical tomography-based dosimeter depends on rayline path through the dosimeter to estimate and reconstruct the dose distribution. The refraction of light passing through a dose region results in artefacts in the reconstructed images. These refraction errors are dependant on the scanning geometry and collection optics. We developed a fully 3D image reconstruction algorithm, algebraic reconstruction technique-refraction correction (ART-rc) that corrects for the refractive index mismatches present in a gel dosimeter scanner not only at the boundary, but also for any rayline refraction due to multiple dose regions inside the dosimeter. In this study, simulation and experimental studies have been carried out to reconstruct a 3D dose volume using 2D CCD measurements taken for various views. The study also focuses on the effectiveness of using different refractive-index matching media surrounding the gel dosimeter. Since the optical density is assumed to be low for a dosimeter, the filtered backprojection is routinely used for reconstruction. We carry out the reconstructions using conventional algebraic reconstruction (ART) and refractive index corrected ART (ART-rc) algorithms. The reconstructions based on FDK algorithm for cone-beam tomography has also been carried out for comparison. Line scanners and point detectors, are used to obtain reconstructions plane by plane. The rays passing through dose region with a RI mismatch does not reach the detector in the same plane depending on the angle of incidence and RI. In the fully 3D scanning setup using 2D array detectors, light rays that undergo refraction are still collected and hence can still be accounted for in the reconstruction algorithm. It is found that, for the central region of the dosimeter, the usable radius using ART-rc algorithm with water as RI matched

  14. Elastic wave speeds and moduli in polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate

    Science.gov (United States)

    Helgerud, M.B.; Waite, W.F.; Kirby, S.H.; Nur, A.

    2009-01-01

    We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate. From the wave speed's linear dependence on temperature and pressure and from the sample's calculated density, we derived expressions for bulk, shear, and compressional wave moduli and Poisson's ratio from -20 to 15??C and 22.4 to 32.8 MPa for ice Ih, -20 to 15??C and 30.5 to 97.7 MPa for si methane hydrate, and -20 to 10??C and 30.5 to 91.6 MPa for sll methane-ethane hydrate. All three materials had comparable P and S wave speeds and decreasing shear wave speeds with increasing applied pressure. Each material also showed evidence of rapid intergranular bonding, with a corresponding increase in wave speed, in response to pauses in sample deformation. There were also key differences. Resistance to uniaxial compaction, indicated by the pressure required to compact initially porous samples, was significantly lower for ice Ih than for either hydrate. The ice Ih shear modulus decreased with increasing pressure, in contrast to the increase measured in both hydrates ?? 2009.

  15. Study on molecular controlled mining system of methane hydrate; Methane hydrate no bunshi seigyo mining ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyagawa, M; Saito, T; Kobayashi, H; Karasawa, H; Kiyono, F; Nagaoki, R; Yamamoto, Y; Komai, T; Haneda, H; Takahashi, Y [National Institute for Resources and Environment, Tsukuba (Japan); Nada, H [Science and Technology Agency, Tokyo (Japan)

    1997-02-01

    Basic studies are conducted for the collection of methane from the methane hydrate that exists at levels deeper than 500m in the sea. The relationship between the hydrate generation mechanism and water cluster structure is examined by use of mass spectronomy. It is found that, among the stable liquid phase clusters, the (H2O)21H{sup +} cluster is the most stable. Stable hydrate clusters are in presence in quantities, and participate in the formation of hydrate crystal nuclei. For the elucidation of the nucleus formation mechanism, a kinetic simulation is conducted of molecules in the cohesion system consisting of water and methane molecules. Water molecules that array near methane molecules at the normal pressure is disarrayed under a higher pressure for rearray into a hydrate structure. Hydrate formation and breakdown in the three-phase equilibrium state of H2O, CH4, and CO2 at a low temperature and high pressure are tested, which discloses that supercooling is required for formation, that it is possible to extract CH4 first for replacement by guest molecule CO2 since CO2 is stabler than CH4 at a lower pressure or higher temperature, and that formation is easier to take place when the grain diameter is larger at the formation point since larger grain diameters result in a higher formation temperature. 3 figs.

  16. Hydrate Evolution in Response to Ongoing Environmental Shifts

    Energy Technology Data Exchange (ETDEWEB)

    Rempel, Alan [Univ. of Oregon, Eugene, OR (United States)

    2015-12-31

    Natural gas hydrates have the potential to become a vital domestic clean-burning energy source. However, past changes in environmental conditions have caused hydrates to become unstable and trigger both massive submarine landslides and the development of crater-like pockmarks, thereby releasing methane into the overlying seawater and atmosphere, where it acts as a powerful greenhouse gas. This project was designed to fill critical gaps in our understanding of domestic hydrate resources and improve forecasts for their response to environmental shifts. Project work can be separated into three interrelated components, each involving the development of predictive mathematical models. The first project component concerns the role of sediment properties on the development and dissociation of concentrated hydrate anomalies. To this end, we developed numerical models to predict equilibrium solubility of methane in twophase equilibrium with hydrate as a function of measureable porous medium characteristics. The second project component concerned the evolution of hydrate distribution in heterogeneous reservoirs. To this end, we developed numerical models to predict the growth and decay of anomalies in representative physical environments. The third project component concerned the stability of hydrate-bearing slopes under changing environmental conditions. To this end, we developed numerical treatments of pore pressure evolution and consolidation, then used "infinite-slope" analysis to approximate the landslide potential in representative physical environments, and developed a "rate-and-state" frictional formulation to assess the stability of finite slip patches that are hypothesized to develop in response to the dissociation of hydrate anomalies. The increased predictive capabilities that result from this work provide a framework for interpreting field observations of hydrate anomalies in terms of the history of environmental forcing that led to their development. Moreover

  17. Electron density analysis of the effects of sugars on the structure of lipid bilayers at low hydration - a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Lenné, T.; Kent, B.; Koster, K.L.; Garvey, C.J.; Bryant, G. (ANSTO); (USD); (ANU); (RMIT)

    2012-02-06

    Small angle X-ray scattering is used to study the effects of sugars on membranes during dehydration. Previous work has shown that the bilayer and chain-chain repeat spacings of DPPC bilayers are relatively unaffected by the presence of sugars. In this work we present a preliminary analysis of the electron density profiles of DPPC in the presence of sugars at low hydration. The difficulties of determining the correct phasing are discussed. Sugars and other small solutes have been shown to have an important role in improving the tolerance of a range of species to desiccation and freezing. In particular it has been shown that sugars can stabilize membranes in the fluid membrane phase during dehydration, and in the fully dehydrated state. Equivalently, at a particular hydration, the presence of sugars lowers the transition temperature between the fluid and gel phases. There are two competing models for explaining the effects of sugars on membrane phase transition temperatures. One, designated the water replacement hypothesis (WRH) states that sugars hydrogen bond to phospholipid headgroups, thus hindering the fluid-gel phase transition. One version of this model suggests that certain sugars (such as trehalose) achieve the measured effects by inserting between the phospholipid head groups. An alternative model explains the observed effects of sugars in terms of the sugars effect on the hydration repulsion that develops between opposing membranes during dehydration. The hydration repulsion leads to a lateral compressive stress in the bilayer which squeezes adjacent lipids more closely together, resulting in a transition to the gel phase. When sugars are present, their osmotic and volumetric effects reduce the hydration repulsion, reduce the compressive stress in the membranes, and therefore tend to maintain the average lateral separation between lipids. This model is called the hydration forces explanation (HFE). We recently showed that neither mono- nor di

  18. Properties of samples containing natural gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well, determined using Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI)

    Science.gov (United States)

    Winters, W.J.

    1999-01-01

    As part of an ongoing laboratory study, preliminary acoustic, strength, and hydraulic conductivity results are presented from a suite of tests conducted on four natural-gas-hydrate-containing samples from the Mackenzie Delta JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The gas hydrate samples were preserved in pressure vessels during transport from the Northwest Territories to Woods Hole, Massachusetts, where multistep tests were performed using GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument), which recreates pressure and temperature conditions that are stable for gas hydrate. Properties and changes in sediment behaviour were measured before, during, and after controlled gas hydrate dissociation. Significant amounts of gas hydrate occupied the sample pores and substantially increased acoustic velocity and shear strength.

  19. Low-δD hydration rinds in Yellowstone perlites record rapid syneruptive hydration during glacial and interglacial conditions

    Science.gov (United States)

    Bindeman, Ilya N.; Lowenstern, Jacob B.

    2016-01-01

    Hydration of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant “onion-skin” fractures. The timing 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 hydration 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 hydration-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 hydration. The hydrated 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 “hydration 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 higher rates of diffusion at 60–110 °C temperatures, compared with values expected from extrapolation of high-temperature (>400 °C) experimental data. The thick hydration rinds in perlites, measuring hundreds of microns, preserve the original D/H values of hydrating water as a recorder of paleoclimate conditions. Measured δD values in perlitic lavas are −150 to −191 or 20–40 ‰ lower than glass hydrated by modern Yellowstone waters. This suggests that Yellowstone perlites record the low-δD signature

  20. PVT Panels. Fully renewable and competitive

    International Nuclear Information System (INIS)

    Bakker, M.; Strootman, K.J.; Jong, M.J.M.

    2003-10-01

    A photovoltaic/thermal (PVT) panel is a combination of photovoltaic cells with a solar thermal collector, generating solar electricity and solar heat simultaneously. PVT panels generate more solar energy per unit surface area than a combination of separate PV panels and solar thermal collectors, and share the aesthetic advantage of PV. After several years of research, PVT panels have been developed into a product that is now ready for market introduction. One of the most promising system concepts, consisting of 25 m 2 of PVT panels and a ground coupled heat pump, has been simulated in TRNSYS, and has been found to be able to fully cover both the building related electricity and heat consumption, while keeping the long-term average ground temperature constant. The cost and payback time of such a system have been determined; it has been found that the payback time of this system is approximately two-thirds of the payback time of an identical system but with 21 m 2 of PV panels and 4 m 2 of solar thermal collectors. Finally, by looking at the expected growth in the PV and solar thermal collector market, the market potential for for PVT panels has been found to be very large

  1. A new fully automated TLD badge reader

    International Nuclear Information System (INIS)

    Kannan, S.; Ratna, P.; Kulkarni, M.S.

    2003-01-01

    At present personnel monitoring in India is being carried out using a number of manual and semiautomatic TLD badge Readers and the BARC TL dosimeter badge designed during 1970. Of late the manual TLD badge readers are almost completely replaced by semiautomatic readers with a number of performance improvements like use of hot gas heating to reduce the readout time considerably. PC based design with storage of glow curve for every dosimeter, on-line dose computation and printout of dose reports, etc. However the semiautomatic system suffers from the lack of a machine readable ID code on the badge and the physical design of the dosimeter card not readily compatible for automation. This paper describes a fully automated TLD badge Reader developed in the RSS Division, using a new TLD badge with machine readable ID code. The new PC based reader has a built-in reader for reading the ID code, in the form of an array of holes, on the dosimeter card. The reader has a number of self-diagnostic features to ensure a high degree of reliability. (author)

  2. Fully inkjet-printed microwave passive electronics

    KAUST Repository

    McKerricher, Garret

    2017-01-30

    Fully inkjet-printed three-dimensional (3D) objects with integrated metal provide exciting possibilities for on-demand fabrication of radio frequency electronics such as inductors, capacitors, and filters. To date, there have been several reports of printed radio frequency components metallized via the use of plating solutions, sputtering, and low-conductivity pastes. These metallization techniques require rather complex fabrication, and do not provide an easily integrated or versatile process. This work utilizes a novel silver ink cured with a low-cost infrared lamp at only 80 °C, and achieves a high conductivity of 1×107 S m−1. By inkjet printing the infrared-cured silver together with a commercial 3D inkjet ultraviolet-cured acrylic dielectric, a multilayer process is demonstrated. By using a smoothing technique, both the conductive ink and dielectric provide surface roughness values of <500 nm. A radio frequency inductor and capacitor exhibit state-of-the-art quality factors of 8 and 20, respectively, and match well with electromagnetic simulations. These components are implemented in a lumped element radio frequency filter with an impressive insertion loss of 0.8 dB at 1 GHz, proving the utility of the process for sensitive radio frequency applications.

  3. The first LHC sector is fully interconnected

    CERN Multimedia

    2006-01-01

    Sector 7-8 is the first sector of the LHC to become fully operational. All the magnets, cryogenic line, vacuum chambers and services are interconnected. The cool down of this sector can soon commence. LHC project leader Lyn Evans, the teams from CERN's AT/MCS, AT/VAC and AT/MEL groups, and the members of the IEG consortium celebrate the completion of the first LHC sector. The 10th of November was a red letter day for the LHC accelerator teams, marking the completion of the first sector of the machine. The magnets of sector 7-8, together with the cryogenic line, the vacuum chambers and the distribution feedboxes (DFBs) are now all completely interconnected. Sector 7-8 has thus been closed and is the first LHC sector to become operational. The interconnection work required several thousand electrical, cryogenic and insulating connections to be made on the 210 interfaces between the magnets in the arc, the 30 interfaces between the special magnets and the interfaces with the cryogenic line. 'This represent...

  4. Fully Resolved Simulations of 3D Printing

    Science.gov (United States)

    Tryggvason, Gretar; Xia, Huanxiong; Lu, Jiacai

    2017-11-01

    Numerical simulations of Fused Deposition Modeling (FDM) (or Fused Filament Fabrication) where a filament of hot, viscous polymer is deposited to ``print'' a three-dimensional object, layer by layer, are presented. A finite volume/front tracking method is used to follow the injection, cooling, solidification and shrinking of the filament. The injection of the hot melt is modeled using a volume source, combined with a nozzle, modeled as an immersed boundary, that follows a prescribed trajectory. The viscosity of the melt depends on the temperature and the shear rate and the polymer becomes immobile as its viscosity increases. As the polymer solidifies, the stress is found by assuming a hyperelastic constitutive equation. The method is described and its accuracy and convergence properties are tested by grid refinement studies for a simple setup involving two short filaments, one on top of the other. The effect of the various injection parameters, such as nozzle velocity and injection velocity are briefly examined and the applicability of the approach to simulate the construction of simple multilayer objects is shown. The role of fully resolved simulations for additive manufacturing and their use for novel processes and as the ``ground truth'' for reduced order models is discussed.

  5. A fully implantable rodent neural stimulator

    Science.gov (United States)

    Perry, D. W. J.; Grayden, D. B.; Shepherd, R. K.; Fallon, J. B.

    2012-02-01

    The ability to electrically stimulate neural and other excitable tissues in behaving experimental animals is invaluable for both the development of neural prostheses and basic neurological research. We developed a fully implantable neural stimulator that is able to deliver two channels of intra-cochlear electrical stimulation in the rat. It is powered via a novel omni-directional inductive link and includes an on-board microcontroller with integrated radio link, programmable current sources and switching circuitry to generate charge-balanced biphasic stimulation. We tested the implant in vivo and were able to elicit both neural and behavioural responses. The implants continued to function for up to five months in vivo. While targeted to cochlear stimulation, with appropriate electrode arrays the stimulator is well suited to stimulating other neurons within the peripheral or central nervous systems. Moreover, it includes significant on-board data acquisition and processing capabilities, which could potentially make it a useful platform for telemetry applications, where there is a need to chronically monitor physiological variables in unrestrained animals.

  6. Microaneurysm detection using fully convolutional neural networks.

    Science.gov (United States)

    Chudzik, Piotr; Majumdar, Somshubra; Calivá, Francesco; Al-Diri, Bashir; Hunter, Andrew

    2018-05-01

    Diabetic retinopathy is a microvascular complication of diabetes that can lead to sight loss if treated not early enough. Microaneurysms are the earliest clinical signs of diabetic retinopathy. This paper presents an automatic method for detecting microaneurysms in fundus photographies. A novel patch-based fully convolutional neural network with batch normalization layers and Dice loss function is proposed. Compared to other methods that require up to five processing stages, it requires only three. Furthermore, to the best of the authors' knowledge, this is the first paper that shows how to successfully transfer knowledge between datasets in the microaneurysm detection domain. The proposed method was evaluated using three publicly available and widely used datasets: E-Ophtha, DIARETDB1, and ROC. It achieved better results than state-of-the-art methods using the FROC metric. The proposed algorithm accomplished highest sensitivities for low false positive rates, which is particularly important for screening purposes. Performance, simplicity, and robustness of the proposed method demonstrates its suitability for diabetic retinopathy screening applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Fully inkjet-printed microwave passive electronics

    KAUST Repository

    McKerricher, Garret; Vaseem, Mohammad; Shamim, Atif

    2017-01-01

    Fully inkjet-printed three-dimensional (3D) objects with integrated metal provide exciting possibilities for on-demand fabrication of radio frequency electronics such as inductors, capacitors, and filters. To date, there have been several reports of printed radio frequency components metallized via the use of plating solutions, sputtering, and low-conductivity pastes. These metallization techniques require rather complex fabrication, and do not provide an easily integrated or versatile process. This work utilizes a novel silver ink cured with a low-cost infrared lamp at only 80 °C, and achieves a high conductivity of 1×107 S m−1. By inkjet printing the infrared-cured silver together with a commercial 3D inkjet ultraviolet-cured acrylic dielectric, a multilayer process is demonstrated. By using a smoothing technique, both the conductive ink and dielectric provide surface roughness values of <500 nm. A radio frequency inductor and capacitor exhibit state-of-the-art quality factors of 8 and 20, respectively, and match well with electromagnetic simulations. These components are implemented in a lumped element radio frequency filter with an impressive insertion loss of 0.8 dB at 1 GHz, proving the utility of the process for sensitive radio frequency applications.

  8. High-Pressure Treatment of Non-Hydrated Flour Affects Structural Characteristics and Hydration

    Directory of Open Access Journals (Sweden)

    Sabina Jakobi

    2018-05-01

    Full Text Available In recent years, high-pressure treatment (HPT has become an established process concerning the preservation of food. However, studies dealing with the structural, and consequently functional modification of non-hydrated starchy matrices (moisture content ≤ 15% by HPT are missing. To close this knowledge gap, pressure (0–600 MPa, 10 min and pressurization time depending (0–20 min, 450 MPa alterations of wheat flour were investigated. Pressure rise from 0 to 600 MPa or pressurization time rise from 0 to 20 min resulted in a decline of amylopectin content from 68.3 ± 2.0% to 59.7 ± 1.5% (linearly, R2 = 0.83 and 59.6 ± 0.7% (sigmoidal, respectively. Thereby, detectable total amount of starch decreased from 77.7 ± 0.8% linearly to 67.6 ± 1.7%, and sigmoidal, to 69.4 ± 0.4%, respectively. Increase in pressure caused a linear decrease in gelatinization enthalpy of 33.2 ± 5.6%, and linear increase in hydration properties by 11.0 ± 0.6%. The study revealed structural and technological relevant alterations of starch-based food matrices with low moisture content by HPT, which must be taken into consideration during processing and preservation of food.

  9. The U.S. Geological Survey’s Gas Hydrates Project

    Science.gov (United States)

    Ruppel, Carolyn D.

    2018-01-17

    The Gas Hydrates Project at the U.S. Geological Survey (USGS) focuses on the study of methane hydrates in natural environments. The project is a collaboration between the USGS Energy Resources and the USGS Coastal and Marine Geology Programs and works closely with other U.S. Federal agencies, some State governments, outside research organizations, and international partners. The USGS studies the formation and distribution of gas hydrates in nature, the potential of hydrates as an energy resource, and the interaction between methane hydrates and the environment. The USGS Gas Hydrates Project carries out field programs and participates in drilling expeditions to study marine and terrestrial gas hydrates. USGS scientists also acquire new geophysical data and sample sediments, the water column, and the atmosphere in areas where gas hydrates occur. In addition, project personnel analyze datasets provided by partners and manage unique laboratories that supply state-of-the-art analytical capabilities to advance national and international priorities related to gas hydrates.

  10. Kinetic Hydration Heat Modeling for High-Performance Concrete Containing Limestone Powder

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone powder is increasingly used in producing high-performance concrete in the modern concrete industry. Limestone powder blended concrete has many advantages, such as increasing the early-age strength, reducing the setting time, improving the workability, and reducing the heat of hydration. This study presents a kinetic model for modeling the hydration heat of limestone blended concrete. First, an improved hydration model is proposed which considers the dilution effect and nucleation effect due to limestone powder addition. A degree of hydration is calculated using this improved hydration model. Second, hydration heat is calculated using the degree of hydration. The effects of water to binder ratio and limestone replacement ratio on hydration heat are clarified. Third, the temperature history and temperature distribution of hardening limestone blended concrete are calculated by combining hydration model with finite element method. The analysis results generally agree with experimental results of high-performance concrete with various mixing proportions.

  11. Rapid hydrogen hydrate growth from non-stoichiometric tuning mixtures during liquid nitrogen quenching.

    Science.gov (United States)

    Grim, R Gary; Kerkar, Prasad B; Sloan, E Dendy; Koh, Carolyn A; Sum, Amadeu K

    2012-06-21

    In this study the rapid growth of sII H(2) hydrate within 20 min of post formation quenching towards liquid nitrogen (LN(2)) temperature is presented. Initially at 72 MPa and 258 K, hydrate samples would cool to the conditions of ~60 MPa and ~90 K after quenching. Although within the stability region for H(2) hydrate, new hydrate growth only occurred under LN(2) quenching of the samples when preformed hydrate "seeds" of THF + H(2) were in the presence of unconverted ice. The characterization of hydrate seeds and the post-quenched samples was performed with confocal Raman spectroscopy. These results suggest that quenching to LN(2) temperature, a common preservation technique for ex situ hydrate analysis, can lead to rapid unintended hydrate growth. Specifically, guest such as H(2) that may otherwise need sufficiently long induction periods to nucleate, may still experience rapid growth through an increased kinetic effect from a preformed hydrate template.

  12. Hydrate phase equilibrium and structure for (methane + ethane + tetrahydrofuran + water) system

    International Nuclear Information System (INIS)

    Sun Changyu; Chen Guangjin; Zhang Lingwei

    2010-01-01

    The separation of methane and ethane through forming hydrate is a possible choice in natural gas, oil processing, or ethylene producing. The hydrate formation conditions of five groups of (methane + ethane) binary gas mixtures in the presence of 0.06 mole fraction tetrahydrofuran (THF) in water were obtained at temperatures ranging from (277.7 to 288.2) K. In most cases, the presence of THF in water can lower the hydrate formation pressure of (methane + ethane) remarkably. However, when the composition of ethane is as high as 0.832, it is more difficult to form hydrate than without THF system. Phase equilibrium model for hydrates containing THF was developed based on a two-step hydrate formation mechanism. The structure of hydrates formed from (methane + ethane + THF + water) system was also determined by Raman spectroscopy. When THF concentration in initial aqueous solution was only 0.06 mole fraction, the coexistence of structure I hydrate dominated by ethane and structure II hydrate dominated by THF in the hydrate sample was clearly demonstrated by Raman spectroscopic data. On the contrary, only structure II hydrate existed in the hydrate sample formed from (methane + ethane + THF + water) system when THF concentration in initial aqueous solution was increased to 0.10 mole fraction. It indicated that higher THF concentration inhibited the formation of structure I hydrate dominated by ethane and therefore lowered the trapping of ethane in hydrate. It implies a very promising method to increase the separation efficiency of methane and ethane.

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

    Science.gov (United States)

    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.

  14. Hydration of Concrete: The First Steps.

    Science.gov (United States)

    Thissen, Peter; Natzeck, Carsten; Giraudo, Nicolas; Weidler, Peter; Wöll, Christof

    2018-04-12

    Concrete is the most important construction material used by mankind and, at the same time, one of the most complex substances known in materials science. Since this mineral compound is highly porous, a better understanding of its surface chemistry, and in particular the reaction with water, is urgently required to understand and avoid corrosion of infrastructure like buildings and bridges. We have gained insight into proton transfer from concrete upon contact with water by applying the so-called Surface Science approach to a well-defined mineral, Wollastonite. Data from IR (infrared) spectroscopy reveal that exposure of this calcium-silicate (CS) substrate to H 2 O leads to dissociation and the formation of OH-species. This proton transfer is a chemical reaction of key importance, since on the one hand it triggers the conversion of cement into concrete (a calcium-silicate-hydrate phase), but on the other hand also governs the corrosion of concrete. Interestingly, we find that no proton transfer takes place when the same surface is exposed to methanol. In order to understand this unexpected difference, the analysis of the spectroscopic data obtained was aided by a detailed, first-principles computational study employing density functional theory (DFT). The combined experimental and theoretical effort allows derivation of a consistent picture of proton transfer reactions occurring in CS and CSH phases. Implications for strategies to protect this backbone of urban infrastructure from corrosion in harsh, aqueous environments will be discussed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Hydration Status of Adult Population of Yazd

    Directory of Open Access Journals (Sweden)

    MH Lotfi

    2008-07-01

    Full Text Available Introduction: Water is an essential nutrient for life. It comprises 75% of total body weight in infants,60% in adult males and 50% in adult females. Decrease in body water is commonly known as dehydration. Acute or chronic dehydration is a common condition in some population groups, especialy the elderly and those who participate in physical activity in warm enviroments. Potential consequences of dehydration include constipation,urinary tract and respiratory infection,urinary stone disease and there might also be an association between a low habitual fluid intake and some carcinomas,cardiovascular disease and diabetes. Many indices have been investigated to establish their role as markers of dehydration status. Body mass changes,blood indices,urine indices and bioelectrical impedance analysis have been used most widely, but current evidence and opinion tend to favour urine indices as the most convenient and sensitive methods. Methods: This cross sectional study was done for estimating the prevalence of dehydration in adult population(students,nurses,officials,workersin Yazd. These persons were selected randomly. Urine samples of two hundred and thirty persons were obtained at 10-12 AM,and urine specific gravity measured by refractometer (all of the samplesand dip stick (some samples. Finding: According to this study,96.7% of our population had some degree of dehydration.69.7% of them were significantly dehydrated(urine SG>1020 and 4.8% of them were severely dehydrated (urine SG>1030 and the mean specific gravity was 1021±5/65. This study evaluated other factors that could probably indicate hydration status like urine colour, type of drink,frequency of urination and frequency of thirst per day. Conclusion: High percentage of our population were dehydrated which was not correlated to the type of drink but was correlated to urine colour, frequency of urination and frequency of thirst. So, regular monitoring of urine to keep if clear or light

  16. Exploring and Monitoring of Methane Hydrate Deposits

    Science.gov (United States)

    Sudac, D.; Obhođaš, J.; Nađ, K.; Valković, V.

    2018-01-01

    Relatively recently, in the last 20 years, it was discovered that methane hydrate (MH) deposits are globally distributed in the permafrost and oceans. Before 1965 when first deposits were discovered in nature, it was believed that MH can occur only in laboratory conditions or in vast parts of the Universe. Presently it is presumed that this solid crystalline compounds in which CH4 molecules occupies the water ice lattices (nominal chemical formula of MH is C4H62O23) can serve as an energy source favorably to the all of the world remaining conventional hydrocarbon sources. The worldwide estimates of MH deposits range from 2x1014 m3 to 3.053x1018 cubic meters. This uncertainty partly results from our limitations in geological understanding of the MH deposits, which is due to the relatively bad quality of data obtained by presently available seismic and electromagnetic techniques. Moreover, MH deposits can become vulnerable to climate changes, which were already occurring in geological past whit tremendous consequences for the global life on Earth. Thus, further development of advanced techniques is needed to enhance our abilities to better characterize, quantify and monitor the MH deposits. In the work presented 14 MeV neutrons and associated alpha particle imaging (API) where used to quantify the amount of MH in the sample. Samples were prepared from sea sediment, quartz sand and MH simulant. MH simulant with chemical formula C4H46O23 was made from sucrose (25 % by mass) and water. MH quantity was measured by measuring the carbon content in the sample [1-8].

  17. Exploring and Monitoring of Methane Hydrate Deposits

    Directory of Open Access Journals (Sweden)

    Sudac D.

    2018-01-01

    Full Text Available Relatively recently, in the last 20 years, it was discovered that methane hydrate (MH deposits are globally distributed in the permafrost and oceans. Before 1965 when first deposits were discovered in nature, it was believed that MH can occur only in laboratory conditions or in vast parts of the Universe. Presently it is presumed that this solid crystalline compounds in which CH4 molecules occupies the water ice lattices (nominal chemical formula of MH is C4H62O23 can serve as an energy source favorably to the all of the world remaining conventional hydrocarbon sources. The worldwide estimates of MH deposits range from 2x1014 m3 to 3.053x1018 cubic meters. This uncertainty partly results from our limitations in geological understanding of the MH deposits, which is due to the relatively bad quality of data obtained by presently available seismic and electromagnetic techniques. Moreover, MH deposits can become vulnerable to climate changes, which were already occurring in geological past whit tremendous consequences for the global life on Earth. Thus, further development of advanced techniques is needed to enhance our abilities to better characterize, quantify and monitor the MH deposits. In the work presented 14 MeV neutrons and associated alpha particle imaging (API where used to quantify the amount of MH in the sample. Samples were prepared from sea sediment, quartz sand and MH simulant. MH simulant with chemical formula C4H46O23 was made from sucrose (25 % by mass and water. MH quantity was measured by measuring the carbon content in the sample [1-8].

  18. Hydration Status in US Military Officer Students.

    Science.gov (United States)

    Rogers, Reva; Cole, Renee

    2016-01-01

    Relocation from a cool to a hot climate is a frequent occurrence in military service. Acclimatization requires time and exposure to heat. Nonacclimatized individuals frequently consume inadequate fluid leading to hypohydration, which can quickly result in dehydration with increased risk of heat illness/injury. This descriptive cross-sectional study assessed the hydration status of 196 officers attending the US Army Medical Department's Officer Basic Course (67%) or Captain's Career Course (33%) in San Antonio, Texas, prior to taking the Army Physical Fitness Test (APFT). Consenting Soldiers provided a first morning void urine sample and demographic survey (age, rank, sex, previous geographic location, etc) prior to the APFT. Height, weight, and APFT event scores were collected from a subject-coded, APFT scorecard without personal information data. Binary logistic regression was performed to identify variables that contribute to predicting hypohydration status. The sample population was 54% male, a mean age of 30 years, 5.2 years of military service, and a mean body mass index of 25 kg/m². Nearly one-third met the criteria for hypohydration (≥1.02 urine specific gravity). Soldiers who relocated from a cool environment within 9 days of taking the APFT had 2.1 higher odds of being hypohydrated compared with individuals who had resided in a hot environment for more than 9 days. Women had a 0.5 lower odds of being hypohydrated as compared to males. Significantly more Soldiers were hypohydrated on Monday compared to those tested on Tuesday (33% vs 16%, P=.004). Given these findings, the authors provided 5 recommendations to reduce the number of Soldiers exercising in a hypohydrated state.

  19. Highly efficient fully transparent inverted OLEDs

    Science.gov (United States)

    Meyer, J.; Winkler, T.; Hamwi, S.; Schmale, S.; Kröger, M.; Görrn, P.; Johannes, H.-H.; Riedl, T.; Lang, E.; Becker, D.; Dobbertin, T.; Kowalsky, W.

    2007-09-01

    One of the unique selling propositions of OLEDs is their potential to realize highly transparent devices over the visible spectrum. This is because organic semiconductors provide a large Stokes-Shift and low intrinsic absorption losses. Hence, new areas of applications for displays and ambient lighting become accessible, for instance, the integration of OLEDs into the windshield or the ceiling of automobiles. The main challenge in the realization of fully transparent devices is the deposition of the top electrode. ITO is commonly used as transparent bottom anode in a conventional OLED. To obtain uniform light emission over the entire viewing angle and a low series resistance, a TCO such as ITO is desirable as top contact as well. However, sputter deposition of ITO on top of organic layers causes damage induced by high energetic particles and UV radiation. We have found an efficient process to protect the organic layers against the ITO rf magnetron deposition process of ITO for an inverted OLED (IOLED). The inverted structure allows the integration of OLEDs in more powerful n-channel transistors used in active matrix backplanes. Employing the green electrophosphorescent material Ir(ppy) 3 lead to IOLED with a current efficiency of 50 cd/A and power efficiency of 24 lm/W at 100 cd/m2. The average transmittance exceeds 80 % in the visible region. The on-set voltage for light emission is lower than 3 V. In addition, by vertical stacking we achieved a very high current efficiency of more than 70 cd/A for transparent IOLED.

  20. Towards a Fully Conservative Water Balance

    Science.gov (United States)

    Rodriguez, L. B.; Vionnet, C. A.; Younger, P. L.; Parkin, G.

    2001-12-01

    Hydrological modeling is nowadays an essential tool in many aspects of water resources assessment and management. For practical purposes, hydrological models may be defined as mathematical procedures, which transform meteorological input data such as precipitation and evapotranspiration into hydrological output values such as riverflows. Conceptual water balance models are one kind of hydrological models still quite popular among engineers and scientists for three main reasons: firstly the "book-keeping" procedure they are based upon makes them computationally inexpensive, secondly, they require far less data than any physically based model, and thirdly, once calibrated and validated, they can yield the proper order of magnitude of the water cycle component on the basin under investigation. A common criticism of water balance models is their lack of sound theoretical basis. In this work a fully conservative water balance model for basin applications which takes into account physical processes is presented. The two-storage level model contains four calibration parameters: a, b, l and Umax. The saturated storage component resembles the abcd model by Thomas, corrected by the presence of the aquifer storativity coefficient s and the river-aquifer interface conductance l. The resulting model is capable of estimating monthly basin-average of actual evapotranspiration, soil moisture, effective groundwater recharge, groundwater level fluctuations, baseflows and direct runoff using an integral form of the mass conservation law in the saturated/unsaturated layers. The model was applied to a 600 Km2 catchment in the United Kingdom. An eight-year record was used for calibration, while a similar record was reserved for validation of model results. Total streamflows as well as baseflows calculated by the model were compared with observed and estimated data. A quite good agreement was obtained. Finally, simulated groundwater levels were compared with observation data collected at

  1. Hydration study of ordinary portland cement in the presence of zinc ions

    Directory of Open Access Journals (Sweden)

    Monica Adriana Trezza

    2007-12-01

    Full Text Available Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD and infrared spectroscopy (IR. Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH32. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

  2. 7 CFR 718.304 - Failure to fully comply.

    Science.gov (United States)

    2010-01-01

    ... authorized in accordance with § 718.305 if the participant made a good faith effort to comply fully with the... FSA approval official to have made a good faith effort to comply fully with the terms and conditions...

  3. Towards CO2 sequestration and applications of CO2 hydrates: the effects of tetrahydrofuran on the phase equilibria of CO2 hydrates

    International Nuclear Information System (INIS)

    Khalik, M.S.; Peters, C.J.

    2006-01-01

    The increasing quantity of carbon dioxide (CO 2 ) in the atmosphere has caused widespread global concerns. Capturing CO 2 from its sources and stored it in the form of gas hydrates and application of CO 2 hydrates are among the proposed methods to overcome this problem. In order to make hydrate-based process more attractive, the use of cyclic ethers as promoters is suggested to reduce the required hydrate formation pressure and enhancing the corresponding kinetic rate. In the present work, tetrahydrofuran (THF) is chosen as a hydrate promoter, participating in forming hydrates and produces mixed hydrate together with CO 2 . The pressure and temperature ranges of hydrate stability region are carefully determined through phase equilibrium measurement of the ternary CO 2 , tetrahydrofuran (THF) and water systems. From the experimental results, it is confirmed that the presence of THF in CO 2 + water systems will extend the hydrate formation region to higher temperature at a constant pressure. The extension of the hydrate stability region is depended on the overall concentration of the ternary system. Moreover, four-phase equilibrium of H-Lw-Lv-V is observed in the system, which may be due to a liquid phase split. In the region where the four-phase equilibrium exists, the ternary system loses its concentration dependency of the hydrate equilibrium conditions. (Author)

  4. Towards a Scalable Fully-Implicit Fully-coupled Resistive MHD Formulation with Stabilized FE Methods

    Energy Technology Data Exchange (ETDEWEB)

    Shadid, J N; Pawlowski, R P; Banks, J W; Chacon, L; Lin, P T; Tuminaro, R S

    2009-06-03

    This paper presents an initial study that is intended to explore the development of a scalable fully-implicit stabilized unstructured finite element (FE) capability for low-Mach-number resistive MHD. The discussion considers the development of the stabilized FE formulation and the underlying fully-coupled preconditioned Newton-Krylov nonlinear iterative solver. To enable robust, scalable and efficient solution of the large-scale sparse linear systems generated by the Newton linearization, fully-coupled algebraic multilevel preconditioners are employed. Verification results demonstrate the expected order-of-acuracy for the stabilized FE discretization of a 2D vector potential form for the steady and transient solution of the resistive MHD system. In addition, this study puts forth a set of challenging prototype problems that include the solution of an MHD Faraday conduction pump, a hydromagnetic Rayleigh-Bernard linear stability calculation, and a magnetic island coalescence problem. Initial results that explore the scaling of the solution methods are presented on up to 4096 processors for problems with up to 64M unknowns on a CrayXT3/4. Additionally, a large-scale proof-of-capability calculation for 1 billion unknowns for the MHD Faraday pump problem on 24,000 cores is presented.

  5. Effect of Oral Hydration on External Cephalic Version at Term.

    Science.gov (United States)

    Zobbi, Virna Franca; Nespoli, Antonella; Spreafico, Elisa; Recalcati, Roberta; Loi, Federica; Scian, Antonietta; Galimberti, Stefania

    To evaluate the effect of oral hydration on the success rate of external cephalic version (ECV). Randomized controlled and single-blind trial. Academic tertiary hospital with approximately 3,000 births annually. One hundred sixty-four women at a gestational age of at least 37 weeks with breech-presenting fetuses and normal amniotic fluid indexes (AFIs). Participants were randomly assigned to drink 2000 ml or no more than 100 ml of water in the 2 hours before undergoing ECV. The AFIs were assessed before and after treatment by the same sonographer, who was blinded to the treatment group. Data were collected on relevant maternal and fetal characteristics and ECV success. The mean AFI after hydration was significantly greater than that in the control group (15.5 cm vs. 13.4 cm, p = .003). The ECV success rate was 53.7% in the hydration group and 46.3% in the control group (odds ratio: 1.34, 95% confidence interval [0.69, 2.59]; p = .349). Hydration was well tolerated and there were no serious adverse events. Oral hydration significantly increased the AFIs but did not affect the success rate of ECVs. Copyright © 2017 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses. Published by Elsevier Inc. All rights reserved.

  6. Integrating Natural Gas Hydrates in the Global Carbon Cycle

    Energy Technology Data Exchange (ETDEWEB)

    David Archer; Bruce Buffett

    2011-12-31

    We produced a two-dimensional geological time- and basin-scale model of the sedimentary margin in passive and active settings, for the simulation of the deep sedimentary methane cycle including hydrate formation. Simulation of geochemical data required development of parameterizations for bubble transport in the sediment column, and for the impact of the heterogeneity in the sediment pore fluid flow field, which represent new directions in modeling methane hydrates. The model is somewhat less sensitive to changes in ocean temperature than our previous 1-D model, due to the different methane transport mechanisms in the two codes (pore fluid flow vs. bubble migration). The model is very sensitive to reasonable changes in organic carbon deposition through geologic time, and to details of how the bubbles migrate, in particular how efficiently they are trapped as they rise through undersaturated or oxidizing chemical conditions and the hydrate stability zone. The active margin configuration reproduces the elevated hydrate saturations observed in accretionary wedges such as the Cascadia Margin, but predicts a decrease in the methane inventory per meter of coastline relative to a comparable passive margin case, and a decrease in the hydrate inventory with an increase in the plate subduction rate.

  7. Role of interlayer hydration in lincomycin sorption by smectite clays.

    Science.gov (United States)

    Wang, Cuiping; Ding, Yunjie; Teppen, Brian J; Boyd, Stephen A; Song, Cunyi; Li, Hui

    2009-08-15

    Lincomycin, an antibiotic widely administered as a veterinary medicine, is frequently detected in water. Little is known about the soil-water distribution of lincomycin despite the fact that this is a major determinant of its environmental fate and potential for exposure. Cation exchange was found to be the primary mechanism responsible for lincomycin sorption by soil clay minerals. This was evidenced by pH-dependent sorption, and competition with inorganic cations for sorptive sites. As solution pH increased, lincomycin sorption decreased. The extent of reduction was consistent with the decrease in cationic lincomycin species in solution. The presence of Ca2+ in solution diminished lincomycin sorption. Clay interlayer hydration status strongly influenced lincomycin adsorption. Smectites with the charge deficit from isomorphic substitution in tetrahedral layers (i.e., saponite) manifest a less hydrated interlayer environment resulting in greater sorption than that by octahedrally substituted clays (i.e., montmorillonite). Strongly hydrated exchangeable cations resulted in a more hydrated clay interlayer environment reducing sorption in the order of Ca- smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces.

  8. Acoustical method of whole-body hydration status monitoring

    Science.gov (United States)

    Sarvazyan, A. P.; Tsyuryupa, S. N.; Calhoun, M.; Utter, A.

    2016-07-01

    An acoustical handheld hydration monitor (HM) for assessing the water balance of the human body was developed. Dehydration is a critical public health problem. Many elderly over age of 65 are particularly vulnerable as are infants and young children. Given that dehydration is both preventable and reversible, the need for an easy-to-perform method for the detection of water imbalance is of the utmost clinical importance. The HM is based on an experimental fact that ultrasound velocity in muscle is a linear function of water content and can be referenced to the hydration status of the body. Studies on the validity of HM for the assessment of whole-body hydration status were conducted in the Appalachian State University, USA, on healthy young adults and on elderly subjects residing at an assisted living facility. The HM was able to track changes in total body water during periods of acute dehydration and rehydration in athletes and day-to-day and diurnal variability of hydration in elderly. Results of human studies indicate that HM has a potential to become an efficient tool for detecting abnormal changes in the body hydration status.

  9. [Prospects for Application of Gases and Gas Hydrates to Cryopreservation].

    Science.gov (United States)

    Shishova, N V; Fesenko, E E

    2015-01-01

    In the present review, we tried to evaluate the known properties of gas hydrates and gases participating in the formation of gas hydrates from the point of view of the mechanisms of cryoinjury and cryoprotection, to consider the papers on freezing biological materials in the presence of inert gases, and to analyze the perspectives for the development of this direction. For the purpose, we searched for the information on the physical properties of gases and gas hydrates, compared processes occured during the formation of gas hydrates and water ice, analyzed the influence of the formation and growth of gas hydrates on the structure of biological objects. We prepared a short review on the biological effects of xenon, krypton, argon, carbon dioxide, hydrogen sulfide, and carbon monoxide especially on hypothermal conditions and probable application of these properties in cryopreservation technologies. The description of the existing experiments on cryopreservation of biological objects with the use of gases was analyzed. On the basis of the information we found, the most perspective directions of work in the field of cryopreservation of biological objects with the use of gases were outlined. An attempt was made to forecast the potential problems in this field.

  10. Modeling the influence of limestone addition on cement hydration

    Directory of Open Access Journals (Sweden)

    Ashraf Ragab Mohamed

    2015-03-01

    Full Text Available This paper addresses the influence of using Portland limestone cement “PLC” on cement hydration by characterization of its microstructure development. The European Standard EN 197-1:2011 and Egyptian specification ESS 4756-1/2009 permit the cement to contain up to 20% ground limestone. The computational tools assist in better understanding the influence of limestone additions on cement hydration and microstructure development to facilitate the acceptance of these more economical and ecological materials. μic model has been developed to enable the modeling of microstructural evolution of cementitious materials. In this research μic model is used to simulate both the influence of limestone as fine filler, providing additional surfaces for the nucleation and growth of hydration products. Limestone powder also reacts relatively slow with hydrating cement to form monocarboaluminate (AFmc phase, similar to the mono-sulfoaluminate (AFm phase formed in ordinary Portland cement. The model results reveal that limestone cement has accelerated cement hydration rate, previous experimental results and computer model “cemhyd3d” are used to validate this model.

  11. Hydrate prevention in petroleum production sub sea system

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Paula L.F.; Rocha, Humberto A.R. [Universidade Estacio de Sa (UNESA), Rio de Janeiro, RJ (Brazil); Rodrigues, Antonio P. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2012-07-01

    In spite of the merits of the several hydrate prevention techniques used nowadays, such as: chemical product injection for inhibition and use of thick thermal insulate lines; hydrates per times happen and they are responsible for considerable production losses. Depressurization techniques can be used so much for prevention as in the remediation. Some hydrate removal techniques need a rig or vessel, resources not readily available and with high cost, reason that limits such techniques just for remediation and not for prevention. In the present work it is proposed and described an innovative depressurization system, remote and resident, for hydrate prevention and removal, applicable as for individual sub sea wells as for grouped wells by manifold. Based on low cost jet pumps, without movable parts and with a high reliability, this technique allows hydrate prevention or remediation in a fast and remote way, operated from the production unit. The power fluid line and fluid return line can be integrated in the same umbilical or annulus line structure, without significant increase in the construction costs and installation. It is not necessary to wait for expensive resource mobilization, sometimes not available quickly, such as: vessels or rigs. It still reduces the chemical product consumption and permits to depressurized stopped lines. Other additional advantage, depressurization procedure can be used in the well starting, removing fluid until riser emptying. (author)

  12. Gas Hydrate Research Database and Web Dissemination Channel

    Energy Technology Data Exchange (ETDEWEB)

    Micheal Frenkel; Kenneth Kroenlein; V Diky; R.D. Chirico; A. Kazakow; C.D. Muzny; M. Frenkel

    2009-09-30

    To facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database {number_sign} 156) was developed by the TRC Group at NIST in Boulder, Colorado paralleling a highly-successful database of thermodynamic properties of molecular pure compounds and their mixtures and in association with an international effort on the part of CODATA to aid in international data sharing. Development and population of this database relied on the development of three components of information-processing infrastructure: (1) guided data capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between 'data producers' and 'data users'. Having developed the appropriate data storage and communication technologies, a web-based interface for both the new Clathrate Hydrate Physical Property Database, as well as Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program was developed and deployed at http://gashydrates.nist.gov.

  13. Modelling the incongruent dissolution of hydrated cement minerals

    International Nuclear Information System (INIS)

    Berner, U.R.

    1988-01-01

    Hydrated calciumsilicates are the main constituents of hydrated portland cements. Their chemistry will strongly influence the longterm behaviour of a concrete system envisioned in use in radioactive waste repositories. Experimental data show that hydrated calciumsilicates dissolve incongruently, depending on the calcium/silicon ratio of the solid. A model that simulates the incongruent dissolution behaviour of these hydrated calciumsilicates is presented. In the model the hydrated calciumcilicates are represented as a mixture of two congruently soluble components. The dissolution of the particular components is described using the concept of variable activities in the solid state. Each component's activity in the solid state is obtained from a large body of solubility data by applying the Gibbs-Duhem equation for nonideal mixtures. Using this approach a simplified set of equations, which describe the solubility of the components as a function of the calcium/silicon ratio of the solid, is derived. As an application, the degradation of a standard portland cement in pure water and in a carbonate-rich groundwater is modelled. (orig.)

  14. The use of hydrated lime in acid mine drainage treatment

    Science.gov (United States)

    Othman, Anuar; Sulaiman, Azli; Sulaiman, Shamsul Kamal

    2017-05-01

    Hydrated lime also known as calcium hydroxide with chemical formula Ca(OH)2 was used in this study as neutralization agent in acid mine drainage (AMD) treatment. Hydrated lime that is used to treat pool water samples from tin tailings located in Pengkalan Hulu, Perak was obtained from Simpang Pulai, Perak. The pH of water sample was around 2.6 to 2.8. Ten different variables of hydrated lime weights were used to treat 1 L of water sample. The weights of hydrated lime used were 0.2 g, 0.4 g, 0.6 g, 0.8 g, 1.0 g, 1.2 g, 1.4 g, 1.6 g, 1.8 g and 2.0 g. Time interval used was every 5 minutes up to minutes 30. Jar test method was used in this study. The maximum pH value of 5.93 ± 0.03 most approaches standard A and had complied standard B have been obtained using 2.0 g hydrated lime in 30-minute time interval. The concentration of arsenic, cadmium and chromium had decreased but only cadmium concentration did not comply with Standards A and B.

  15. Methane Hydrate Field Program. Development of a Scientific Plan for a Methane Hydrate-Focused Marine Drilling, Logging and Coring Program

    Energy Technology Data Exchange (ETDEWEB)

    Collett, Tim [U.S. Geological Survey, Boulder, CO (United States); Bahk, Jang-Jun [Korea Inst. of Geoscience and Mineral Resources, Daejeon (Korea); Frye, Matt [U.S. Bureau of Ocean Energy Management, Sterling, VA (United States); Goldberg, Dave [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Husebo, Jarle [Statoil ASA, Stavenger (Norway); Koh, Carolyn [Colorado School of Mines, Golden, CO (United States); Malone, Mitch [Texas A & M Univ., College Station, TX (United States); Shipp, Craig [Shell International Exploration and Production Inc., Anchorage, AK (United States); Torres, Marta [Oregon State Univ., Corvallis, OR (United States); Myers, Greg [Consortium For Ocean Leadership Inc., Washington, DC (United States); Divins, David [Consortium For Ocean Leadership Inc., Washington, DC (United States); Morell, Margo [Consortium For Ocean Leadership Inc., Washington, DC (United States)

    2013-12-31

    This topical report represents a pathway toward better understanding of the impact of marine methane hydrates on safety and seafloor stability and future collection of data that can be used by scientists, engineers, managers and planners to study climate change and to assess the feasibility of marine methane hydrate as a potential future energy resource. Our understanding of the occurrence, distribution and characteristics of marine methane hydrates is incomplete; therefore, research must continue to expand if methane hydrates are to be used as a future energy source. Exploring basins with methane hydrates has been occurring for over 30 years, but these efforts have been episodic in nature. To further our understanding, these efforts must be more regular and employ new techniques to capture more data. This plan identifies incomplete areas of methane hydrate research and offers solutions by systematically reviewing known methane hydrate “Science Challenges” and linking them with “Technical Challenges” and potential field program locations.

  16. Randomized trial of one-hour sodium bicarbonate vs standard periprocedural saline hydration in chronic kidney disease patients undergoing cardiovascular contrast procedures.

    Directory of Open Access Journals (Sweden)

    Judith Kooiman

    Full Text Available Guidelines advise periprocedural saline hydration for prevention of contrast induced-acute kidney injury (CI-AKI. We analysed whether 1-hour sodium bicarbonate hydration administered solely prior to intra-arterial contrast exposure is non-inferior to standard periprocedural saline hydration in chronic kidney disease (CKD patients undergoing elective cardiovascular diagnostic or interventional contrast procedures.We performed an open-label multicentre non-inferiority trial between 2011-2014. Patients were randomized to 1 hour pre-procedure sodium bicarbonate hydration (250 ml 1.4%, N = 168 or 4-12 hours saline hydration (1000 ml 0.9%, N = 165 prior to and following contrast administration (2000 ml of saline total. Primary outcome was the relative serum creatinine increase (% 48-96 hours post contrast exposure. Secondary outcomes were: incidence of CI-AKI (serum creatinine increase>25% or >44μmol/L, recovery of renal function, the need for dialysis, and hospital costs within two months follow-up.Mean relative creatinine increase was 3.1% (95%CI 0.9 to 5.2% in the bicarbonate and 1.1% (95%CI -1.2 to 3.5% in the saline arm, mean difference 1.9% (95%CI -1.2 to 5.1%, p-non-inferiority <0.001. CI-AKI occurred in 11 (6.7% patients randomized to sodium bicarbonate and 12 (7.5% to saline (p = 0.79. Renal function did not fully recover in 40.0% and 44.4% of CI-AKI patients, respectively (p = 0.84. No patient required dialysis. Mean costs for preventive hydration and clinical preparation for the contrast procedure were $1158 for sodium bicarbonate vs. $1561 for saline (p < 0.001.Short hydration with sodium bicarbonate prior to elective cardiovascular diagnostic or therapeutic contrast procedures is non-inferior to standard periprocedural saline hydration in CKD patients with respect to renal safety and results in considerable healthcare savings.Netherlands Trial Register (http://www.trialregister.nl/trialreg/index.asp, Nr NTR2699.

  17. Randomized trial of one-hour sodium bicarbonate vs standard periprocedural saline hydration in chronic kidney disease patients undergoing cardiovascular contrast procedures.

    Science.gov (United States)

    Kooiman, Judith; de Vries, Jean-Paul P M; Van der Heyden, Jan; Sijpkens, Yvo W J; van Dijkman, Paul R M; Wever, Jan J; van Overhagen, Hans; Vahl, Antonie C; Aarts, Nico; Verberk-Jonkers, Iris J A M; Brulez, Harald F H; Hamming, Jaap F; van der Molen, Aart J; Cannegieter, Suzanne C; Putter, Hein; van den Hout, Wilbert B; Kilicsoy, Inci; Rabelink, Ton J; Huisman, Menno V

    2018-01-01

    Guidelines advise periprocedural saline hydration for prevention of contrast induced-acute kidney injury (CI-AKI). We analysed whether 1-hour sodium bicarbonate hydration administered solely prior to intra-arterial contrast exposure is non-inferior to standard periprocedural saline hydration in chronic kidney disease (CKD) patients undergoing elective cardiovascular diagnostic or interventional contrast procedures. We performed an open-label multicentre non-inferiority trial between 2011-2014. Patients were randomized to 1 hour pre-procedure sodium bicarbonate hydration (250 ml 1.4%, N = 168) or 4-12 hours saline hydration (1000 ml 0.9%, N = 165) prior to and following contrast administration (2000 ml of saline total). Primary outcome was the relative serum creatinine increase (%) 48-96 hours post contrast exposure. Secondary outcomes were: incidence of CI-AKI (serum creatinine increase>25% or >44μmol/L), recovery of renal function, the need for dialysis, and hospital costs within two months follow-up. Mean relative creatinine increase was 3.1% (95%CI 0.9 to 5.2%) in the bicarbonate and 1.1% (95%CI -1.2 to 3.5%) in the saline arm, mean difference 1.9% (95%CI -1.2 to 5.1%, p-non-inferiority <0.001). CI-AKI occurred in 11 (6.7%) patients randomized to sodium bicarbonate and 12 (7.5%) to saline (p = 0.79). Renal function did not fully recover in 40.0% and 44.4% of CI-AKI patients, respectively (p = 0.84). No patient required dialysis. Mean costs for preventive hydration and clinical preparation for the contrast procedure were $1158 for sodium bicarbonate vs. $1561 for saline (p < 0.001). Short hydration with sodium bicarbonate prior to elective cardiovascular diagnostic or therapeutic contrast procedures is non-inferior to standard periprocedural saline hydration in CKD patients with respect to renal safety and results in considerable healthcare savings. Netherlands Trial Register (http://www.trialregister.nl/trialreg/index.asp), Nr NTR2699.

  18. New approach to solve symmetric fully fuzzy linear systems

    Indian Academy of Sciences (India)

    concepts of fuzzy set theory and then define a fully fuzzy linear system of equations. .... To represent the above problem as fully fuzzy linear system, we represent x .... Fully fuzzy linear systems can be solved by Linear programming approach, ...

  19. An effective medium inversion algorithm for gas hydrate quantification and its application to laboratory and borehole measurements of gas hydrate-bearing sediments

    Science.gov (United States)

    Chand, S.; Minshull, T.A.; Priest, J.A.; Best, A.I.; Clayton, C.R.I.; Waite, W.F.

    2006-01-01

    The presence of gas hydrate in marine sediments alters their physical properties. In some circumstances, gas hydrate may cement sediment grains together and dramatically increase the seismic P- and S-wave velocities of the composite medium. Hydrate may also form a load-bearing structure within the sediment microstructure, but with different seismic wave attenuation characteristics, changing the attenuation behaviour of the composite. Here we introduce an inversion algorithm based on effective medium modelling to infer hydrate saturations from velocity and attenuation measurements on hydrate-bearing sediments. The velocity increase is modelled as extra binding developed by gas hydrate that strengthens the sediment microstructure. The attenuation increase is modelled through a difference in fluid flow properties caused by different permeabilities in the sediment and hydrate microstructures. We relate velocity and attenuation increases in hydrate-bearing sediments to their hydrate content, using an effective medium inversion algorithm based on the self-consistent approximation (SCA), differential effective medium (DEM) theory, and Biot and squirt flow mechanisms of fluid flow. The inversion algorithm is able to convert observations in compressional and shear wave velocities and attenuations to hydrate saturation in the sediment pore space. We applied our algorithm to a data set from the Mallik 2L–38 well, Mackenzie delta, Canada, and to data from laboratory measurements on gas-rich and water-saturated sand samples. Predictions using our algorithm match the borehole data and water-saturated laboratory data if the proportion of hydrate contributing to the load-bearing structure increases with hydrate saturation. The predictions match the gas-rich laboratory data if that proportion decreases with hydrate saturation. We attribute this difference to differences in hydrate formation mechanisms between the two environments.

  20. Experimental Investigation into the Combustion Characteristics of Propane Hydrates in Porous Media

    Directory of Open Access Journals (Sweden)

    Xiang-Ru Chen

    2015-02-01

    Full Text Available The combustion characteristics of both pure propane hydrates and the mixtures of hydrates and quartz sands were investigated by combustion experiments. The flame propagation, flame appearance, burning time and temperature in different hydrate layers were studied. For pure propane hydrate combustion, the initial flame falls in the “premixed” category. The flame propagates very rapidly, mainly as a result of burnt gas expansion. The flame finally self-extinguishes with some proportion of hydrates remaining unburned. For the hydrate-sand mixture combustion, the flame takes the form of many tiny discontinuous flames appearing and disappearing at different locations. The burn lasts for a much shorter amount of time than pure hydrate combustion. High porosity and high hydrate saturation is beneficial to the combustion. The hydrate combustion is the combustion of propane gas resulting from the dissociation of the hydrates. In both combustion test scenarios, the hydrate-dissociated water plays a key role in the fire extinction, because it is the main resistance that restrains the heat transfer from the flame to the hydrates and that prevents the hydrate-dissociated gas from releasing into the combustion zone.

  1. Effect of changes in seafloor temperature and sea-level on gas hydrate stability

    Energy Technology Data Exchange (ETDEWEB)

    Garg, S.K.; Pritchett, W. [Science Applications International Corp., San Diego, CA (United States)

    2008-07-01

    Natural gas hydrates occur in oceanic sediments and in permafrost regions around the world. As a greenhouse gas, large amounts of methane released from the global hydrate reservoir would have a significant impact on Earth's climate. The role of methane released by hydrate dissociation in climate change is uncertain. However, changes in global climate such as glaciation and warming can destabilize the hydrates. During the last glacial maximum, the sea level dropped about 100 meters. It has been suggested that the sea-level fall was associated with gas hydrate instability and seafloor slumping. This paper investigated the effect of changes in seafloor temperature and sea level on gas hydrate stability and on gas venting at the seafloor. A one-dimensional numerical computer model (simulator) was developed to describe methane hydrate formation, decomposition, reformation, and distribution with depth below the seafloor in the marine environment. The simulator was utilized to model hydrate distributions at two sites, notably Blake Ridge, located offshore South Carolina and Hydrate Ridge, located off the coast of Oregon. The numerical models for the two sites were conditioned by matching the sulfate, chlorinity, and hydrate distribution measurements. The effect of changes in seafloor temperature and sea-level on gas hydrate stability were then investigated. It was concluded that for Blake Ridge, changes in hydrate concentration were small. Both the changes in seafloor temperature and sea-level led to a substantial increase in gas venting at the seafloor for Hydrate Ridge. 17 refs., 8 figs.

  2. Assessment of beverage intake and hydration status.

    Science.gov (United States)

    Nissensohn, Mariela; López-Ufano, Marisa; Castro-Quezada, Itandehui; Serra-Majem, Lluis

    2015-02-26

    Water is the main constituent of the human body. It is involved in practically all its functions. It is particularly important for thermoregulation and in the physical and cognitive performance. Water balance reflects water intake and loss. Intake of water is done mainly through consumption of drinking water and beverages (70 to 80%) plus water containing foods (20 to 30%). Water loss is mainly due to excretion of water in urine, faeces and sweat. The interest in the type and quantity of beverage consumption is not new, and numerous approaches have been used to assess beverage intake, but the validity of these approaches has not been well established. There is no standardized questionnaire developed as a research tool for the evaluation of water intake in the general population. Sometimes, the information comes from different sources or from different methodological characteristics which raises problems of the comparability. In the European Union, current epidemiological studies that focus exclusively on beverage intake are scarce. Biomarkers of intake are able to objectively assess dietary intake/status without the bias of self-reported dietary intake errors and also overcome the problem of intra-individual diet variability. Furthermore, some methods of measuring dietary intake used biomarkers to validate the data it collects. Biological markers may offer advantages and be able to improve the estimates of dietary intake assessment, which impact into the statistical power of the study. There is a surprising paucity of studies that systematically examine the correlation of beverages intake and hydration biomarker in different populations. A pilot investigation was developed to evaluate the comparative validity and reliability of newly developed interactive multimedia (IMM) versions compared to validated paper-administered (PP) versions of the Hedrick et al. beverage questionnaire. The study showed that the IMM appears to be a valid and reliable measure to assess

  3. On the conditions of preparation of hydrated rare earth orthovanadates

    Energy Technology Data Exchange (ETDEWEB)

    Nakhodnova, A P; Belousova, E E; Shuba, Yu I; Zaslavskij, L V

    1988-10-01

    The properties of Ln(NO/sub 3/)/sub 3/-Na/sub 3/VO/sub 4/-H/sub 2/O solution series, where Ln is Er, Ho, Eu are investigated by the methods of residual concentrations, conductometry and potentiometry. It is found that at equivalent ratios of the initial components LnVO/sub 4/xmH/sub 2/O hydrated orthovanadates are formed. Deviations towards excess of rare earths or vanadium result in contamination of the compounds by products of side reactions. According to the data on X-ray phase analysis, hydrated erbium, holmium, europium orthovanadates have the zirconium crystal structure typical for anhydrous compounds. It is shown that hydrate water, being a component of orthovanadates, can be referred to adsorbed and interlayer water.

  4. On the conditions of preparation of hydrated rare earth orthovanadates

    International Nuclear Information System (INIS)

    Nakhodnova, A.P.; Belousova, E.E.; Shuba, Yu.I.; Zaslavskij, L.V.

    1988-01-01

    The properties of Ln(NO 3 ) 3 -Na 3 VO 4 -H 2 O solution series, where Ln is Er, Ho, Eu are investigated by the methods of residual concentrations, conductometry and potentiometry. It is found that at equivalent ratios of the initial components LnVO 4 xmH 2 O hydrated orthovanadates are formed. Deviations towards excess of rare earths or vanadium result in contamination of the compounds by products of side reactions. According to the data on X-ray phase analysis, hydrated erbium, holmium, europium orthovanadates have the zirconium crystal structure typical for anhydrous compounds. It is shown that hydrate water, being a component of orthovanadates, can be referred to adsorbed and interlayer water

  5. Halting of the calcium aluminate cement hydration process

    International Nuclear Information System (INIS)

    Luz, A.P.; Borba, N.Z; Pandolfelli, V.C.

    2011-01-01

    The calcium aluminate cement reactions with water lead to the anhydrous phases dissolution resulting a saturated solution, followed by nucleation and crystal growth of the hydrate compounds. This is a dynamic process, therefore, it is necessary to use suitable methods to halt the hydration in order to study the phase transformations kinetics of such materials. In this work two methods are evaluated: use of acetone and microwave drying, aiming to withdraw the free water and inhibit further reactions. X ray diffraction and thermogravimetric tests were used to quantify the phases generated in the cement samples which were kept at 37 deg C for 1 to 15 days. The advantages and disadvantages of those procedures are presented and discussed. The use of microwave to halt the hydration process seems to be effective to withdraw the cement free water, and it can further be used in researches of the refractory castables area, endodontic cements, etc. (author)

  6. The melting curve of tetrahydrofuran hydrate in D2O

    International Nuclear Information System (INIS)

    Hanley, H.J.M.; Meyers, G.J.; White, J.W.; Sloan, E.D.

    1989-01-01

    Melting points for the tetrahydrofuran/D 2 O hydrate in equilibrium with the air-saturated liquid at atmospheric pressure are reported. The melting points were measured by monitoring the absorbance of the solution. Overall, the melting-point phase boundary curve is about 2.5 K greater than the corresponding curve for the H 2 O hydrate, with a congruent melting temperature of 281 ± 0.5 K at a D 2 O mole fraction of 0.936. The phase boundary is predicted to within 5% if the assumption is made that the THF occupancy in the D 2 O and H 2 O hydrates is the same. The authors measure an occupancy of 99.9%. The chemical potential of the empty lattice in D 2 O is estimated to be 5% greater than in H 2 O

  7. Soluble salts addition modifies MgO hydration

    International Nuclear Information System (INIS)

    Santos, A.M.; Pandolfelli, V.C.; Salomao, R.

    2012-01-01

    Magnesium oxide (MgO) show great technological interest on refractories due to its high refractoriness, basic slag corrosion resistance and competitive cost. However, the hydration reaction of MgO produces magnesium hydroxide. This reaction generates a significant volumetric expansion that can lead to material breakdown inhibiting its use in refractory castables. This reaction can be affected by several factors such as magnesia source, purity, calcination temperature, pH, CaO/SiO 2 ratio and agitation speed. In the present work, soluble salts (CaCl 2 and MgCl 2 ) were used in MgO aqueous suspensions (caustic and sinter). The results were evaluated by means of techniques of degree of hydration (termogravimetric), Scanning electron microscopy, apparent volumetric expansion and x-ray Diffraction which showed that the degree of hydration was noticeably less to sinter aqueous and the expansive effects were less with the addition of CaCl 2 . (author)

  8. Hydration Phase Diagram of Clay Particles from Molecular Simulations.

    Science.gov (United States)

    Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

    2017-11-07

    Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

  9. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    Science.gov (United States)

    Warzinski, Robert P.; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J.; Levine, Jonathan S.

    2014-10-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing gas to reach shallower depths and the atmosphere. The precise nature and influence of hydrate coatings on bubble hydrodynamics and dissolution is largely unknown. Here we present high-definition, experimental observations of complex surficial mechanisms governing methane bubble hydrate formation and dissociation during transit of a simulated oceanic water column that reveal a temporal progression of deep-sea controlling mechanisms. Synergistic feedbacks between bubble hydrodynamics, hydrate morphology, and coverage characteristics were discovered. Morphological changes on the bubble surface appear analogous to macroscale, sea ice processes, presenting new mechanistic insights. An inverse linear relationship between hydrate coverage and bubble dissolution rate is indicated. Understanding and incorporating these phenomena into bubble and bubble plume models will be necessary to accurately predict global greenhouse gas budgets for warming ocean scenarios and hydrocarbon transport from anthropogenic or natural deep-sea eruptions.

  10. Broadband Seismic Studies at the Mallik Gas Hydrate Research Well

    Science.gov (United States)

    Sun, L. F.; Huang, J.; Lyons-Thomas, P.; Qian, W.; Milkereit, B.; Schmitt, D. R.

    2005-12-01

    The JAPEX/JNOC/GSC et al. Mallik 3L-38, 4L-38 and 5L-38 scientific wells were drilled in the MacKenzie Delta, NWT, Canada in early 2002 primarily for carrying out initial tests of the feasibility of producing methane gas from the large gas hydrate deposits there [1]. As part of this study, high resolution seismic profiles, a pseudo-3D single fold seismic volume and broadband (8~180Hz) multi-offset vertical seismic profiles (VSP) were acquired at the Mallik site. Here, we provide details on the acquisition program, present the results of the 2D field profile, and discuss the potential implications of these observations for the structure of the permafrost and gas hydrate zones. These zones have long been problematic in seismic imaging due to the lateral heterogeneities. Conventional seismic data processing usually assume a stratified, weak-contrast elastic earth model. However, in permafrost and gas hydrate zones this approximation often becomes invalid. This leads to seismic wave scattering caused by multi-scale perturbation of elastic properties. A 3D viscoelastic finite difference modeling algorithm was employed to simulate wave propagation in a medium with strong contrast. Parameters in this modeling analysis are based on the borehole geophysical log data. In addition, an uncorrelated Vibroseis VSP data set was studied to investigate frequency-dependent absorption and velocity dispersion. Our results indicate that scattering and velocity dispersion are important for a better understanding of attenuation mechanisms in heterogeneous permafrost and gas hydrate zones. [1] Dallimore, S.R., Collett, T.S., Uchida, T., and Weber, M., 2005, Overview of the science program for the Mallik 2002 Gas Hydrate Production Research Well Program; in Scientific Results from Mallik 2002 Gas Hydrate production Research Well Program, MacKenzie Delta, Northwest Territories, Canada, (ed.) S.R. Dallimore and T.S. Collett; Geological Survey of Canada, Bulletin 585, in press.

  11. Probing the hydration water diffusion of macromolecular surfaces and interfaces

    International Nuclear Information System (INIS)

    Ortony, Julia H; Cheng, Chi-Yuan; Franck, John M; Pavlova, Anna; Hunt, Jasmine; Han, Songi; Kausik, Ravinath

    2011-01-01

    We probe the translational dynamics of the hydration water surrounding the macromolecular surfaces of selected polyelectrolytes, lipid vesicles and intrinsically disordered proteins with site specificity in aqueous solutions. These measurements are made possible by the recent development of a new instrumental and methodological approach based on Overhauser dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy. This technique selectively amplifies 1 H NMR signals of hydration water around a spin label that is attached to a molecular site of interest. The selective 1 H NMR amplification within molecular length scales of a spin label is achieved by utilizing short-distance range (∼r -3 ) magnetic dipolar interactions between the 1 H spin of water and the electron spin of a nitroxide radical-based label. Key features include the fact that only minute quantities (<10 μl) and dilute (≥100 μM) sample concentrations are needed. There is no size limit on the macromolecule or molecular assembly to be analyzed. Hydration water with translational correlation times between 10 and 800 ps is measured within ∼10 A distance of the spin label, encompassing the typical thickness of a hydration layer with three water molecules across. The hydration water moving within this time scale has significant implications, as this is what is modulated whenever macromolecules or molecular assemblies undergo interactions, binding or conformational changes. We demonstrate, with the examples of polymer complexation, protein aggregation and lipid-polymer interaction, that the measurements of interfacial hydration dynamics can sensitively and site specifically probe macromolecular interactions.

  12. Methane hydrates in marine sediments - Untapped source of energy

    Digital Repository Service at National Institute of Oceanography (India)

    Jauhari, P.

    (Egorov et al 1999). Many known gas seep areas and mud volcanoes are characterised by the formation of authigenic carbonates. In the Gulf of Mexico, which is the best studied area, the association of bacterial mats, gas hydrates and authigenic carbonates... of methane hydrates offshore southern Mexico. In : Watkins, J.S., Moore J.R. et al. (Eds). Initial Reports deep Sea Drilling Project Leg 66. Washington, D.C., US Government Printing Office, pp. 547-556. Singh, A., & Singh, B.D. 1999. Methane Gas...

  13. Methods of gas hydrate concentration estimation with field examples

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, D.; Dash, R.; Dewangan, P.

    physics and seismic inversion: examples from the northern deepwater Gulf of Mexico: The Leading Edge, 23, 60-66. Dash R., 2007, Crustal structure and marine gas hydrate studies near Vancouver Island using seismic tomography: PhD thesis, University...-resistivity logs: Examples from Green Canyon, Gulf of Mexico: SEG expanded abstracts, 26, 1579-1583. Singh, S. C., Minshull, T. A., and Spence, G. D., 1993, Velocity structure of a gas hydrate reflector: Science, 260, 204-207. Sloan, E. D. Jr., 1998, Clathrate...

  14. Hydration of ammonia, methylamine, and methanol in amorphous solid water

    Science.gov (United States)

    Souda, Ryutaro

    2016-02-01

    Interactions of polar protic molecules with amorphous solid water (ASW) have been investigated using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. The ammonia and methylamine are incorporated into the interior of porous ASW films. They are caged by water molecules and are released during water crystallization. In contrast, the methanol-water interaction is not influenced by pores of ASW. The methanol additives tend to survive water crystallization and are released during ASW film evaporation. The hydration of n-hexane in ASW is influenced significantly by methanol additives because n-hexane is accommodated in a methanol-induced hydration shell.

  15. Frozen heat: Global outlook on methane gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Beaudoin, Yannick; Solgaard, Anne

    2010-09-15

    The United Nations Environment Programme via its collaborating center in Norway, UNEP/GRID-Arendal, is undertaking an assessment of the state of the knowledge of methane gas hydrates. The Global Outlook on Methane Gas Hydrates seeks to bridge the gap between the science, research and development activities related to this potential large scale unconventional source of natural gas and the needs of decision makers and the general public to understand the underlying societal and environmental drivers and impacts. The Outlook aims to provide credible and unbiased information sourced from stakeholders representing the environment, government, industry and society.

  16. Adaptive resolution simulation of a biomolecule and its hydration shell: Structural and dynamical properties

    International Nuclear Information System (INIS)

    Fogarty, Aoife C.; Potestio, Raffaello; Kremer, Kurt

    2015-01-01

    A fully atomistic modelling of many biophysical and biochemical processes at biologically relevant length- and time scales is beyond our reach with current computational resources, and one approach to overcome this difficulty is the use of multiscale simulation techniques. In such simulations, when system properties necessitate a boundary between resolutions that falls within the solvent region, one can use an approach such as the Adaptive Resolution Scheme (AdResS), in which solvent particles change their resolution on the fly during the simulation. Here, we apply the existing AdResS methodology to biomolecular systems, simulating a fully atomistic protein with an atomistic hydration shell, solvated in a coarse-grained particle reservoir and heat bath. Using as a test case an aqueous solution of the regulatory protein ubiquitin, we first confirm the validity of the AdResS approach for such systems, via an examination of protein and solvent structural and dynamical properties. We then demonstrate how, in addition to providing a computational speedup, such a multiscale AdResS approach can yield otherwise inaccessible physical insights into biomolecular function. We use our methodology to show that protein structure and dynamics can still be correctly modelled using only a few shells of atomistic water molecules. We also discuss aspects of the AdResS methodology peculiar to biomolecular simulations

  17. Adaptive resolution simulation of a biomolecule and its hydration shell: Structural and dynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Fogarty, Aoife C., E-mail: fogarty@mpip-mainz.mpg.de; Potestio, Raffaello, E-mail: potestio@mpip-mainz.mpg.de; Kremer, Kurt, E-mail: kremer@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2015-05-21

    A fully atomistic modelling of many biophysical and biochemical processes at biologically relevant length- and time scales is beyond our reach with current computational resources, and one approach to overcome this difficulty is the use of multiscale simulation techniques. In such simulations, when system properties necessitate a boundary between resolutions that falls within the solvent region, one can use an approach such as the Adaptive Resolution Scheme (AdResS), in which solvent particles change their resolution on the fly during the simulation. Here, we apply the existing AdResS methodology to biomolecular systems, simulating a fully atomistic protein with an atomistic hydration shell, solvated in a coarse-grained particle reservoir and heat bath. Using as a test case an aqueous solution of the regulatory protein ubiquitin, we first confirm the validity of the AdResS approach for such systems, via an examination of protein and solvent structural and dynamical properties. We then demonstrate how, in addition to providing a computational speedup, such a multiscale AdResS approach can yield otherwise inaccessible physical insights into biomolecular function. We use our methodology to show that protein structure and dynamics can still be correctly modelled using only a few shells of atomistic water molecules. We also discuss aspects of the AdResS methodology peculiar to biomolecular simulations.

  18. Molecular dynamics simulations of the three-layer hydrate of Na-montmorillonite

    International Nuclear Information System (INIS)

    Holmboe, Michael; Bourg, Ian C.

    2012-01-01

    the size of hundreds to tens or hundreds of thousands particles, MD simulations can be used to reveal how dynamic processes on the macro-scale (such as laboratory-scale values of the EA of diffusion), arise from the molecular scale. In order to obtain accurate and realistic transport properties of solutes in clays, such as self-diffusion coefficients, sorption behavior and EA of diffusion, one must probe realistic and physically relevant geochemical systems. Many previous studies using molecular simulation techniques studied relatively small smectite/water systems ( 4 atoms) using 'frozen' smectite clay layers, in order to save computational time, whereas the use of fully flexible clay layers has been advocated by several authors. In this study we present a sensitivity analysis of MD simulations of the three-layer hydrate of Na-montmorillonite. We focus in particular on the self-diffusion coefficients and their temperature-dependence, as well as structural data for the three-layer hydration state, which is expected to be the predominant hydration state in the bentonite barrier in different concepts of geological nuclear waste disposal, such as the Swedish KBS-3 concept. We also present a methodology for calculating the EA of diffusion for solutes in the interlayer nano-pores for temperatures 278 to 353 K, correcting for system size effects inherent to MD simulations as well as viscosity related effects for the SPC/E water model. In brief, our methodology uses the versatile MD code LAMMPS with a rigid SPC/E water model and the CLAYFF force field, which is known to satisfyingly predict structural and thermodynamical properties of smectite interlayer water and exchangeable cations. The CLAYFF force field describes the non-bonded atomic partial charges together with the van der Waals parameters of the clay structural atoms, which in this study is a typical 2:1 Na + -exchanged smectite (Wyoming montmorillonite) containing a negative structural charge of 0.66/unit cell

  19. Gas hydrates stability zone thickness map of Indian deep offshore areas - A GIS based approach

    Digital Repository Service at National Institute of Oceanography (India)

    Rastogi, A.; Deka, B.; Bhattacharya, G.C.; Ramprasad, T.; KameshRaju, K.A.; Srinivas, K.; Murty, G.P.S.; Chaubey, A.K.; Ramana, M.V.; Subrahmanyam, V.; Sarma, K.V.L.N.S.; Desa, M.; Paropkari, A.L.; Menezes, A.A.A.; Murty, V.S.N.; Antony, M.K.; SubbaRaju, L.V.; Desa, E.; Veerayya, M.

    hydrate occurrence in offshore regions and around the Indian sub-continent. This was accomplished by estimating the gas hydrate stability zone (GHSZ) thickness from the saptial analysis of the physical parameters that control the formation and stability...

  20. Estimating pore-space gas hydrate saturations from well log acoustic data

    Science.gov (United States)

    Lee, Myung W.; Waite, William F.

    2008-07-01

    Relating pore-space gas hydrate saturation to sonic velocity data is important for remotely estimating gas hydrate concentration in sediment. In the present study, sonic velocities of gas hydrate-bearing sands are modeled using a three-phase Biot-type theory in which sand, gas hydrate, and pore fluid form three homogeneous, interwoven frameworks. This theory is developed using well log compressional and shear wave velocity data from the Mallik 5L-38 permafrost gas hydrate research well in Canada and applied to well log data from hydrate-bearing sands in the Alaskan permafrost, Gulf of Mexico, and northern Cascadia margin. Velocity-based gas hydrate saturation estimates are in good agreement with Nuclear Magneto Resonance and resistivity log estimates over the complete range of observed gas hydrate saturations.

  1. A constitutive mechanical model for gas hydrate bearing sediments incorporating inelastic mechanisms

    KAUST Repository

    Sá nchez, Marcelo; Gai, Xuerui; Santamarina, Carlos

    2016-01-01

    , hydrates dissociate and move from the solid to the gas phase. Hydrate dissociation is accompanied by significant changes in sediment structure and strongly affects its mechanical behavior (e.g., sediment stiffenss, strength and dilatancy). The mechanical

  2. Analysis of Decomposition for Structure I Methane Hydrate by Molecular Dynamics Simulation

    Science.gov (United States)

    Wei, Na; Sun, Wan-Tong; Meng, Ying-Feng; Liu, An-Qi; Zhou, Shou-Wei; Guo, Ping; Fu, Qiang; Lv, Xin

    2018-05-01

    Under multi-nodes of temperatures and pressures, microscopic decomposition mechanisms of structure I methane hydrate in contact with bulk water molecules have been studied through LAMMPS software by molecular dynamics simulation. Simulation system consists of 482 methane molecules in hydrate and 3027 randomly distributed bulk water molecules. Through analyses of simulation results, decomposition number of hydrate cages, density of methane molecules, radial distribution function for oxygen atoms, mean square displacement and coefficient of diffusion of methane molecules have been studied. A significant result shows that structure I methane hydrate decomposes from hydrate-bulk water interface to hydrate interior. As temperature rises and pressure drops, the stabilization of hydrate will weaken, decomposition extent will go deep, and mean square displacement and coefficient of diffusion of methane molecules will increase. The studies can provide important meanings for the microscopic decomposition mechanisms analyses of methane hydrate.

  3. Experimental Equipment Validation for Methane (CH4) and Carbon Dioxide (CO2) Hydrates

    Science.gov (United States)

    Saad Khan, Muhammad; Yaqub, Sana; Manner, Naathiya; Ani Karthwathi, Nur; Qasim, Ali; Mellon, Nurhayati Binti; Lal, Bhajan

    2018-04-01

    Clathrate hydrates are eminent structures regard as a threat to the gas and oil industry in light of their irritating propensity to subsea pipelines. For natural gas transmission and processing, the formation of gas hydrate is one of the main flow assurance delinquent has led researchers toward conducting fresh and meticulous studies on various aspects of gas hydrates. This paper highlighted the thermodynamic analysis on pure CH4 and CO2 gas hydrates on the custom fabricated equipment (Sapphire cell hydrate reactor) for experimental validation. CO2 gas hydrate formed at lower pressure (41 bar) as compared to CH4 gas hydrate (70 bar) while comparison of thermodynamic properties between CH4 and CO2 also presented in this study. This preliminary study could provide pathways for the quest of potent hydrate inhibitors.

  4. Gas composition and isotopic geochemistry of cuttings, core, and gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well

    Science.gov (United States)

    Lorenson, T.D.

    1999-01-01

    Molecular and isotopic composition of gases from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well demonstrate that the in situ gases can be divided into three zones composed of mixtures of microbial and thermogenic gases. Sediments penetrated by the well are thermally immature; thus the sediments are probably not a source of thermogenic gas. Thermogenic gas likely migrated from depths below 5000 m. Higher concentrations of gas within and beneath the gas hydrate zone suggest that gas hydrate is a partial barrier to gas migration. Gas hydrate accumulations occur wholly within zone 3, below the base of permafrost. The gas in gas hydrate resembles, in part, the thermogenic gas in surrounding sediments and gas desorbed from lignite. Gas hydrate composition implies that the primary gas hydrate form is Structure I. However, Structure II stabilizing gases are more concentrated and isotopically partitioned in gas hydrate relative to the sediment hosting the gas hydrate, implying that Structure II gas hydrate may be present in small quantities.

  5. Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

    Science.gov (United States)

    Zhang, Huaiwen; Cheng, Yuanfang; Li, Qingchao; Yan, Chuanliang; Han, Xiuting

    2018-02-01

    Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7°C, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep

  6. Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media

    Science.gov (United States)

    Seol, Yongkoo; Kneafsey, Timothy J.

    2011-08-01

    An experimental study was performed using X-ray computed tomography (CT) scanning to capture three-dimensional (3-D) methane hydrate distributions and potential discrete flow pathways in a sand pack sample. A numerical study was also performed to develop and analyze empirical relations that describe the impacts of hydrate accumulation habits within pore space (e.g., pore filling or grain cementing) on multiphase fluid migration. In the experimental study, water was injected into a hydrate-bearing sand sample that was monitored using an X-ray CT scanner. The CT images were converted into numerical grid elements, providing intrinsic sample data including porosity and phase saturations. The impacts of hydrate accumulation were examined by adapting empirical relations into the flow simulations as additional relations governing the evolution of absolute permeability of hydrate bearing sediment with hydrate deposition. The impacts of pore space hydrate accumulation habits on fluid migration were examined by comparing numerical predictions with experimentally measured water saturation distributions and breakthrough curves. A model case with 3-D heterogeneous initial conditions (hydrate saturation, porosity, and water saturation) and pore body-preferred hydrate accumulations best captured water migration behavior through the hydrate-bearing sample observed in the experiment. In the best matching model, absolute permeability in the hydrate bearing sample does not decrease significantly with increasing hydrate saturation until hydrate saturation reaches about 40%, after which it drops rapidly, and complete blockage of flow through the sample can occur as hydrate accumulations approach 70%. The result highlights the importance of permeability modification due to hydrate accumulation habits when predicting multiphase flow through high-saturation, reservoir quality hydrate-bearing sediments.

  7. High voltage microscopy of the hydration of cement with special respect to the influence of superplasticizers

    International Nuclear Information System (INIS)

    Pusch, R.; Fredrikson, A.

    1990-02-01

    This report describes a study of cement hydration, using high voltage 'humid cell' electron microscopy. Samples with and without superplasticizer were inserted in the humid cell, thus allowing the superplasticizer to affect the hydration process while observing it in the microscope. It is concluded that after an initial period of rather rapid hydration, further hydration is retarded by the superplasticizer. It probably forms a Helmholtz-type cloud of organic molecules around cement grains. (authors)

  8. Topological modeling of methane hydrate crystallization from low to high water cut emulsion systems

    OpenAIRE

    Melchuna , Aline; Cameirão , Ana; Herri , Jean-Michel; Glénat , Philippe

    2016-01-01

    International audience; Hydrate formation and remediation in oil flowlines facilities represent a major concern for oil industry in respect of capital and operational costs. It is necessary to have a better understanding on the hydrate formation process to be more efficient in hydrate prevention, especially in respect to additive dosage. This work is a contribution to enhance the knowledge of hydrate formation at high water cuts, by introducing new techniques of analysis in the Archimede flow...

  9. Thermodynamic stability and guest distribution of CH4/N2/CO2 mixed hydrates for methane hydrate production using N2/CO2 injection

    International Nuclear Information System (INIS)

    Lim, Dongwook; Ro, Hyeyoon; Seo, Yongwon; Seo, Young-ju; Lee, Joo Yong; Kim, Se-Joon; Lee, Jaehyoung; Lee, Huen

    2017-01-01

    Highlights: • We examine the thermodynamic stability and guest distribution of CH 4 /N 2 /CO 2 mixed hydrates. • Phase equilibria of the CH 4 /N 2 /CO 2 mixed hydrates were measured to determine the thermodynamic stability. • The N 2 /CO 2 ratio of the hydrate phase is almost constant despite the enrichment of CO 2 in the hydrate phase. • 13 C NMR results indicate the preferential occupation of N 2 and CO 2 in the small and large cages of sI hydrates, respectively. - Abstract: In this study, thermodynamic stability and cage occupation behavior in the CH 4 – CO 2 replacement, which occurs in natural gas hydrate reservoirs by injecting flue gas, were investigated with a primary focus on phase equilibria and composition analysis. The phase equilibria of CH 4 /N 2 /CO 2 mixed hydrates with various compositions were measured to determine the thermodynamic stability of gas hydrate deposits replaced by N 2 /CO 2 gas mixtures. The fractional experimental pressure differences (Δp/p) with respect to the CSMGem predictions were found to range from −0.11 to −0.02. The composition analysis for various feed gas mixtures with a fixed N 2 /CO 2 ratio (4.0) shows that CO 2 is enriched in the hydrate phase, and the N 2 /CO 2 ratio in the hydrate phase is independent of the feed CH 4 fractions. Moreover, 13 C NMR measurements indicate that N 2 molecules preferentially occupy the small 5 12 cages of sI hydrates while the CO 2 molecules preferentially occupy the large 5 12 6 2 cages, resulting in an almost constant area ratio of CH 4 molecules in the large to small cages of the CH 4 /N 2 /CO 2 mixed hydrates. The overall experimental results provide a better understanding of stability conditions and guest distributions in natural gas hydrate deposits during CH 4 – flue gas replacement.

  10. Volatile inventories in clathrate hydrates formed in the primordial nebula.

    Science.gov (United States)

    Mousis, Olivier; Lunine, Jonathan I; Picaud, Sylvain; Cordier, Daniel

    2010-01-01

    The examination of ambient thermodynamic conditions suggests that clathrate hydrates could exist in the Martian permafrost, on the surface and in the interior of Titan, as well as in other icy satellites. Clathrate hydrates are probably formed in a significant fraction of planetesimals in the solar system. Thus, these crystalline solids may have been accreted in comets, in the forming giant planets and in their surrounding satellite systems. In this work, we use a statistical thermodynamic model to investigate the composition of clathrate hydrates that may have formed in the primordial nebula. In our approach, we consider the formation sequence of the different ices occurring during the cooling of the nebula, a reasonable idealization of the process by which volatiles are trapped in planetesimals. We then determine the fractional occupancies of guests in each clathrate hydrate formed at a given temperature. The major ingredient of our model is the description of the guest-clathrate hydrate interaction by a spherically averaged Kihara potential with a nominal set of parameters, most of which are fitted to experimental equilibrium data. Our model allows us to find that Kr, Ar and N2 can be efficiently encaged in clathrate hydrates formed at temperatures higher than approximately 48.5 K in the primitive nebula, instead of forming pure condensates below 30 K. However, we find at the same time that the determination of the relative abundances of guest species incorporated in these clathrate hydrates strongly depends on the choice of the parameters of the Kihara potential and also on the adopted size of cages. Indeed, by testing different potential parameters, we have noted that even minor dispersions between the different existing sets can lead to non-negligible variations in the determination of the volatiles trapped in clathrate hydrates formed in the primordial nebula. However, these variations are not found to be strong enough to reverse the relative abundances

  11. Hydration of swelling clays: multi-scale sequence of hydration and determination of macroscopic energies from microscopic properties; Hydratation des argiles gonflantes: sequence d'hydratation multi-echelle determination des energies macroscopiques a partir des proprietes microscopiques

    Energy Technology Data Exchange (ETDEWEB)

    Salles, F

    2006-10-15

    Smectites have interesting properties which make them potential candidates for engineered barriers in deep geological nuclear waste repository: low permeability, swelling and cations retention. The subject of this thesis consists in the determination of the relationship between hydration properties, swelling properties and cations mobility in relation with confinement properties of clayey materials. The aim is to understand and to predict the behaviour of water in smectites, following two research orientations: the mechanistic aspects and the energetic aspects of the hydration of smectites. We worked on the Na-Ca montmorillonite contained in the MX80 bentonite, with the exchanged homo ionic structure (saturated with alkaline cations and calcium cations). The approach crosses the various scales (microscopic, mesoscopic and macroscopic) and implied the study of the various components of the system (layer-cation-water), by using original experimental methods (thermo-poro-metry and electric conductivity for various relative humidities (RH) and electrostatic calculations. Initially, the dry state is defined by SCTA (scanning calorimetry thermal analysis). Then a classical characterization of the smectite porosity for the dry state is carried out using mercury intrusion and nitrogen adsorption. We evidenced the existence of a meso-porosity which radius varies from 2 to 10 nm depending on the compensating cation. The thermo-poro-metry and conductivity experiments performed at various hydration states made it possible to follow the increase in the pore sizes and the cations mobility as a function of the hydration state. We highlight in particular the existence of an osmotic mesoscopic swelling for low RH (approximately 50-60%RH for Li and Na). By combining the results of thermo-poro-metry, X-ray diffraction and electric conductivity, we are able to propose a complete hydration sequence for each cation, showing the crucial role of the compensating cation in the hydration of

  12. Recycle of fired phosphogypsum waste product as a cement replacement and its role on the hydration and strength development of pastes

    International Nuclear Information System (INIS)

    Tantawi, S.H.

    2005-01-01

    The effect of Partially up to fully substituted of treated phosphogypsum x(PG) for natural gypsum on the physico- mechanical as well as kinetic of hydration of ordinary Portland cement has been discussed . The results show that by increasing PG % the water to cement ratio decreased while the initial and final setting times increased So PG acts as a retarder and water reducer . The retardation effect may be attributed to formation of ettringite layer which formed on the surface of C3A of cement pastes . The chemically combined water, free lime content and bulk density increased with curing time and with PG content for all cement pastes up to 90 days due to increasing of the rate of hydration. The compressive strength increased by increasing of PG % due to formation of anhydrite , changes in major oxides content and reduction of impurities . X-Ray Diffraction, SEM and DTA of some samples have been studied

  13. Obsidian hydration rate for the klamath basin of california and Oregon.

    Science.gov (United States)

    Johnson, L

    1969-09-26

    A hydration rate for obsidian of 3.5(4) microns squared per 1000 radio-carbon years has been established at the Nightfire Island archeological site in northern California and provides a means to date other prehistoric Klamath Basin sites. The new rate follows the form of the hydration equation formulated by Friedman and helps to refute claims made for other hydration equations.

  14. Kinetics of CO2 and methane hydrate formation : an experimental analysis in the bulk phase

    NARCIS (Netherlands)

    He, Y.; Rudolph, E.S.J.; Zitha, P.L.J.; Golombok, M.

    2011-01-01

    Gas resources captured in the form of gas hydrates are by an order of magnitude larger than the resources available from conventional resources. In order to keep the CO2CO2 footprint in the world as small as possible, the idea is to produce methane hydrates and sequestrate CO2CO2 into hydrates in

  15. Molecular analysis of petroleum derived compounds that adsorb onto gas hydrate surfaces

    International Nuclear Information System (INIS)

    Borgund, Anna E.; Hoiland, Sylvi; Barth, Tanja; Fotland, Per; Askvik, Kjell M.

    2009-01-01

    Field observations have shown that some streams of water, gas and crude oil do not form gas hydrate plugs during petroleum production even when operating within thermodynamic conditions for hydrate formation. Also, when studied under controlled laboratory conditions, some oils are found to form hydrate dispersed systems whereas others form plugs. Oils with low tendency to form hydrate plugs are believed to contain natural hydrate plug inhibiting components (NICs) that adsorb onto the hydrate surface, making them less water-wet and preventing the particles from agglomerating into large hydrate clusters. The molecular structure of the NICs is currently unknown. In this work, hydrate adsorbing components were extracted from crude oils using freon hydrates as an extraction phase. The fractions were found to be enriched in polar material, and more polar material is associated with hydrates generated in biodegraded crude oils than in non-biodegraded oils. Various fractionation schemes and analytical techniques have been applied in the search for molecular characterisation. The average molecular weights were found to be approximately 500 g/mole. GC-MS chromatograms show a large UCM (Unresolved Complex Mixture). Thus, GC-MS has a limited potential for identification of compounds. A commercial biosurfactant was used as a model compound in the search for similar structures in the extracts. The results from analysis of the hydrate adsorbing components suggest that the type and structure are more important for hydrate morphology than the amount of material adsorbed.

  16. The hydration of slag, part 1: reaction models for blended cement

    NARCIS (Netherlands)

    Chen, Wei; Brouwers, Jos

    2007-01-01

    Reaction models are proposed to quantify the hydration products and to determine the composition of C–S–H from alkali-activated slags (AAS). Products of the slag hydration are first summarized from o