WorldWideScience

Sample records for hydrated minerals exposed

  1. 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.

  2. Hydrated Minerals on Asteroids: The Astronomical Record

    Science.gov (United States)

    Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.

    2003-01-01

    Knowledge of the hydrated mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest times in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5-micron regions, which are diagnostic of or associated with hydrated minerals. Observations in those regions show that hydrated minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings as well. Asteroid groups formerly associated with mineralogies assumed to have high-temperature formation, such as M- and E-class steroids, have been observed to have hydration features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and Hydroxl-bearing minerals on asteroids.

  3. Chemical characteristics of mineral trioxide aggregate and its hydration reaction

    OpenAIRE

    Chang, Seok-woo

    2012-01-01

    Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyap...

  4. Phase field theory modeling of methane fluxes from exposed natural gas hydrate reservoirs

    Science.gov (United States)

    Kivelä, Pilvi-Helinä; Baig, Khuram; Qasim, Muhammad; Kvamme, Bjørn

    2012-12-01

    Fluxes of methane from offshore natural gas hydrate into the oceans vary in intensity from massive bubble columns of natural gas all the way down to fluxes which are not visible within human eye resolution. The driving force for these fluxes is that methane hydrate is not stable towards nether minerals nor towards under saturated water. As such fluxes of methane from deep below hydrates zones may diffuse through fluid channels separating the hydrates from minerals surfaces and reach the seafloor. Additional hydrate fluxes from hydrates dissociating towards under saturated water will have different characteristics depending on the level of dynamics in the actual reservoirs. If the kinetic rate of hydrate dissociation is smaller than the mass transport rate of distributing released gas into the surrounding water through diffusion then hydrodynamics of bubble formation is not an issue and Phase Field Theory (PFT) simulations without hydrodynamics is expected to be adequate [1, 2]. In this work we present simulated results corresponding to thermodynamic conditions from a hydrate field offshore Norway and discuss these results with in situ observations. Observed fluxes are lower than what can be expected from hydrate dissociating and molecularly diffusing into the surrounding water. The PFT model was modified to account for the hydrodynamics. The modified model gave higher fluxes, but still lower than the observed in situ fluxes.

  5. The formation of goethite and hydrated clay minerals on Mars

    Science.gov (United States)

    Huguenin, R. L.

    1974-01-01

    Laboratory studies reported by Huguenin (1973) on the kinetics and mechanism of the photostimulated oxidation of magnetic and preliminary laboratory data on the weathering of silicates, reported herein, are applied to Mars. Basalts in the Martian dark areas are predicted to alter to hydrated Fe(2 plus or minus) depleted clay minerals, minor goethite, and minor to trace amounts of transition metal oxides such as TiO2, MnO2, and Cr2O3 at a rate of 10 to the minus 1.5 plus or minus 1.5 micron/yr. Some Ca-Mg carbonates are also expected to be formed. The clay minerals are predicted to be more silica-rich than the silicate source material, SiO2 contents of 60% or higher being expected, and strongly depleted in Fe(2+). The oxygen, OH, and H2O contents of the bulk weathering product are predicted to be significantly greater than those of the dark-area source materials, whereas the relative bulk metal abundances should be the same.

  6. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    OpenAIRE

    Salam, A.; Lohmann, U.; Lesins, G.

    2007-01-01

    The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100%) and diluted ammonia gas (25 ppm) at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure...

  7. Formation of nitrous oxide (N2O) hydrate in soil mineral suspensions with electrolytes

    Science.gov (United States)

    Kyung, D.; Enkh-Amgalan, T.; Lee, W.

    2013-05-01

    We have identified the effects of solid surface (illite, nontronite, sphalerite, kaolinite) and electrolyte (NaCl, KCl, CaCl2, MgCl2) types on the formation of N2O hydrate in this study. The hydrate formation experiments were conducted at hydrate forming condition (273.3K and 30 bar) by injecting N2O gas into the soil mineral suspensions with and without electrolytes in a 50mL pressurized vessel. The formation of N2O hydrate in aqueous electrolyte solutions was slower than that in deionized water. Ion charge and size were significant factors affecting N2O hydrate formation kinetic in electrolytes solutions. The addition of soil mineral suspensions accelerated the formation of N2O hydrate in the electrolyte solutions. Surface area and ionic strength of soil minerals highly influenced on formation kinetic of N2O hydrate. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. The results obtained from this research could be indirectly applied to the fate of N2O sequestered into geological formations as well as its storage as a form of N2O hydrate.

  8. New silica clathrate minerals that are isostructural with natural gas hydrates.

    Science.gov (United States)

    Momma, Koichi; Ikeda, Takuji; Nishikubo, Katsumi; Takahashi, Naoki; Honma, Chibune; Takada, Masayuki; Furukawa, Yoshihiro; Nagase, Toshiro; Kudoh, Yasuhiro

    2011-01-01

    Silica clathrate compounds (clathrasils) and clathrate hydrates are structurally analogous because both materials have framework structures with cage-like voids occupied by guest species. The following three structural types of clathrate hydrates are recognized in nature: cubic structure I (sI); cubic structure II (sII); and hexagonal structure H (sH). In contrast, only one naturally occurring silica clathrate mineral, melanophlogite (sI-type framework), has been found to date. Here, we report the discovery of two new silica clathrate minerals that are isostructural with sII and sH hydrates and contain hydrocarbon gases. Geological and mineralogical observations show that these silica clathrate minerals are traces of low-temperature hydrothermal systems at convergent plate margins, which are the sources of thermogenic natural gas hydrates. Given the widespread occurrence of submarine hydrocarbon seeps, silica clathrate minerals are likely to be found in a wide range of marine sediments. PMID:21326228

  9. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    Directory of Open Access Journals (Sweden)

    A. Salam

    2007-01-01

    Full Text Available The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100% and diluted ammonia gas (25 ppm at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas exposure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw and 5 to 8 times at 100% RHw for 120 min exposure time within our experimental conditions. The percentages of active ice nuclei were 2 to 9 times higher at 90% RHw and 2 to 13 times higher at 100% RHw in 25 ppm ammonia exposed montmorillonite compared to unexposed montmorillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreasing temperatures. The activation temperature of montmorillonite exposed to 100% pure ammonia was 12°C higher than for unexposed montmorillonite particles at 90% RHw and 10°C higher at 100% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 7°C warmer than unexposed montmorillonite at 100% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles. This is the first experimental evidence that ammonia gas exposed montmorillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10°C where natural atmospheric ice nuclei are very scarce.

  10. Screening and surveillance of workers exposed to mineral dusts

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, G.R.

    1997-12-31

    This publication resulted from a World Health Organisation initiated project to investigate the harmonisation of definitions, approaches and methodologies for the screening and surveillance of workers exposed to mineral dust. The first part of the book provides definitions of screening and surveillance and describes the main elements of such programmes. The second part discusses the practical aspect of the screening and surveillance of working populations exposed to crystalline silica, coal mine dust and asbestos. Although no single set of guidelines is applicable to the development and implementation of a programme for the screening and surveillance of workers exposed to mineral dust, the recommendations, together with certain caveats, should provide a useful starting point. Annexes provide examples of existing programmes in various countries and environments and discuss the use and interpretation of questionnaires, lung spirometry and chest radiography. Overall the book should be of interest to occupational health professionals.

  11. MODELING OF CATION BINDING IN HYDRATED 2:1 CLAY MINERALS

    Science.gov (United States)

    Hydrated 2:1 clay minerals are high-surface area, layered silicates that play a unique role in determining the fate of ionic pollutants in the environment. These minerals, including smectites and vermiculites, make up a major component of many soils. Ionic pollutants, including r...

  12. Effect of electrolytes and soil mineral surfaces on N2O hydrate formation kinetics

    Science.gov (United States)

    Kyung, D.; Ha, S.; Lee, W.

    2013-12-01

    Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by IPCC (Intergovernmental Panel on Climate Change) and its global warming potential (GWP) is 310 times higher than that of carbon dioxide (CO2). Gas hydrates are unique crystalline compounds that trap suitable guest gas molecules (size between 0.35 and 0.9 nm) stably inside the hydrogen-bonded water cages via van der Waals interaction under high pressure and low temperature conditions. N2O has similar properties (e.g. van der Waals diameter, molar mass, density, etc.) with CO2 except for polarity and it was revealed that both N2O and CO2 can be formed as hydrate s-I in natural environment. In this study, we have identified the effect of electrolytes (NaCl, KCl, CaCl2, MgCl2) and solid surfaces (illite, nontronite, sphalerite, kaolinite, montmorillonite) on the N2O hydrate formation kinetics. The hydrate formation experiments were conducted by injecting N2O gas into the soil mineral suspensions with and without electrolytes in a 50mL pressurized vessel. The formation of N2O hydrate in aqueous electrolyte solutions was slower than that in deionized water. Ion charge and size were significant factors affecting N2O hydrate formation kinetic in electrolytes solutions. The addition of soil mineral suspensions accelerated the formation of N2O hydrate in the electrolyte solutions. Surface area and ionic strength of soil minerals highly influenced on formation kinetic of N2O hydrate. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. The results obtained from this research could be indirectly applied to the fate of N2O sequestered into geological formations as well as its storage as a form of N2O hydrate.

  13. Effect of pH on carbon dioxide hydrate formation in mixed soil mineral suspensions.

    Science.gov (United States)

    Lamorena, Rheo B; Lee, Woojin

    2009-08-01

    We investigated the effect of pH on CO2 hydrate formation in the presence of phyllosilicate mixtures. Different pH conditions of phyllosilicate suspensions (Na-montmorillonite-rich and phyllosilicate-rich suspensions) with and without NaCl (3.5%) were prepared and controlled by the addition of an acid or base before the dissolution of CO2. The formation of CO2 hydrates was observed in all phyllosilicate suspensions (30 bar and 273.45 K). The temperature-time plot results showed that hydrate formations were suppressed more in acidic mineral suspensions than in basic suspensions. The fastest hydrate induction time can be observed in Na-montmorillonite-rich and phyllosilicate-rich suspensions with and without NaCl at near neutral conditions (pH 6-8), followed by basic (approximately pH 12.0) and acidic (approximately pH 2.0) pHs. Hydrate induction time can be significantly affected by various chemical species forming under different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEOC, and used for the identification of hydrate formation characteristics in the suspension. Particle-particle and particle-water interactions may possibly contribute to the delay of hydrate formation. NaCl was not an efficient inhibitor but a possible promoter for hydrate formation when pH-dependent solid surfaces were present in the system. PMID:19731696

  14. Study on the composition and hydration of alinite and calcium chloroaluminate minerals

    International Nuclear Information System (INIS)

    The alinites and calcium chloroaluminates are main minerals of ecocement. In this paper, the alinite and calcium chloroaluminate minerals are synthesized. Analytical reagents are mixed into the raw meals of alinite and calcium chloroaluminate that are burnt under different temperatures. Through the content of f-CaO detection and XRD analysis, we have confirmed the firing condition. Especially, the scanning electron microscope SEM-EDS analysis are used to test and analyze the composition and hydration mechanism of the minerals

  15. Formation of carbon dioxide hydrate in soil and soil mineral suspensions with electrolytes.

    Science.gov (United States)

    Lamorena, Rheo B; Lee, Woojin

    2008-04-15

    We have identified the effects of solid surface (soil, bentonite, kaolinite, nontronite, and pyrite) and electrolyte (NaCl, KCl, CaCl2, and MgCl2) types on the formation and dissociation of CO2 hydrate in this study. The hydrate formation experiments were conducted by injecting CO2 gas into the soil suspensions with and without electrolytes in a 50 mL pressurized vessel. The formation of CO2 hydrate in deionized water was faster than that in aqueous electrolyte solutions. The addition of soil suspensions accelerated the formation of CO2 hydrate in the electrolyte solutions. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. We did not observe any significant differences between the hydrate dissociation in the solid suspension and that in the deionized water. The pHs of clay mineral suspensions decreased significantly after CO2 hydrate formation and dissociation experiments, while the pH of the soil suspension slightly decreased by less than pH 1 and that of pyrite slightly increased due to the dissolution of CO2 forming carbonic acid. The results obtained from this research could be indirectly applied to the fate of CO2 sequestered into geological formations as well as its storage as a form of CO2 hydrate. PMID:18497119

  16. FINAL REPORT. MODELING OF CATION BINDING IN HYDRATED 2:1 CLAY MINERALS

    Science.gov (United States)

    Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swellin...

  17. Microbeam recoil detection for hydration of minerals studies

    Energy Technology Data Exchange (ETDEWEB)

    Sie, S.H.; Suter, G.F. [CSIRO, North Ryde, NSW (Australia). Exploration and Mining Div.; Chekhmir, A.; Green, T.H. [Macquarie Univ., North Ryde, NSW (Australia)

    1993-12-31

    The glancing angle geometry is chosen to enable application of the elastic recoil detection microanalysis on thick geological samples, for hydrogen content determination. Simultaneous PIXE measurements can be used to eliminate the problem of uncertainties in beam charge collection. The method is applied to determine the hydration characteristics of silicates, produced experimentally at high pressure and temperature simulating the lower crust and upper mantle conditions. Preliminary results show that the technique can be applied readily on a microscopic (<100 {mu}m) scale for determination of H at fraction of atomic percent level. 9 refs., 3 figs.

  18. Methane hydrate behavior when exposed to a 23% carbon dioxide 77% nitrogen gas under conditions similar to the ConocoPhillips 2012 Ignik Sikumi Gas Hydrate Field Trial

    Science.gov (United States)

    Borglin, S. E.; Kneafsey, T. J.; Nakagawa, S.

    2013-12-01

    In-situ replacement of methane hydrate by carbon dioxide hydrate is considered to be a promising technique for producing natural gas, while simultaneously sequestering greenhouse gas in deep geological formations. For effective application of this technique in the field, kinetic models of gas exchange rates in hydrate under a variety of environmental conditions need to be established, and the impact of hydrate substitution on geophysical (seismic) properties has to be quantified in order to optimize monitoring techniques. We performed a series of laboratory tests in which we monitored changes in methane hydrate-bearing samples while a nitrogen/carbon dioxide gas mixture was flowed through. These experiments were conducted to gain insights into data obtained from a field test in which the same mixture of carbon dioxide and nitrogen was injected into a methane hydrate-bearing unit beneath the north slope of the Brooks Range in northern Alaska (ConocoPhillips 2012 Ignik Sikumi gas hydrate field trial). We have measured the kinetic gas exchange rate for a range of hydrate saturations and different test configurations, to provide an estimate for comparison to numerical model predictions. In our tests, the exchange rate decreased over time during the tests as methane was depleted from the system. Following the elution of residual gaseous methane, the exchange rate ranged from 3.8×10-7 moles methane/(mole water*s) to 5×10-8 moles methane/(mole water*s) (Note that in these rates, the moles of water refers to water originally held in the hydrate.). In addition to the gas exchange rate, we also monitored changes in permeability occurring due to the gas substitution. Further, we determined the seismic P and S wave velocities and attenuations using our Split Hopkinson Resonant Bar apparatus (e.g. Nakagawa, 2012, Rev. Sci. Instr.). In addition to providing geophysical signatures, changes in the seismic properties can also be related to changes in the mechanical strength of the hydrate-bearing sand resulting from exposure to the mixed gas. Upon introduction of the mixed gas, the sample became less stiff and wave attenuation increased, indicating the presence of liquid water between mineral grains and hydrate. Slow dissociation of hydrate conducted in this experiment showed a range of hydrate stability conditions as the gas composition changed from dissociation and dilution of the previously injected nitrogen.

  19. CO2 + N2O mixture gas hydrate formation kinetics and effect of soil minerals on mixture-gas hydrate formation process

    Science.gov (United States)

    Enkh-Amgalan, T.; Kyung, D.; Lee, W.

    2012-12-01

    CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) hydrate formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make hydrate to mitigate N20 and CO2 in same time. Mixture gas hydrate formation periods were approximately two times faster than pure N2O hydrate formation kinetic in general. The fastest induction time of mixture-gas hydrate formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that hydrate formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on hydrate formation kinetic; however, induction time can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of hydrate formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas hydrates. We have also performed molecular dynamics computer simulations on N2O and CO2 hydrate structures to estimate the residual free energy of two-phase (hydrate cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O hydrates are thermodynamically stable at real-world gas hydrate existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be efficiently applied to CO2 sequestration at potential sites and further investigations must be conducted to identify possible effects frequently found in natural geological environments and geo-environmental conditions at the site affecting the hydrate formation kinetics.

  20. Modeling of Cation Binding in Hydrated 2:1 Clay Minerals - Final Report

    International Nuclear Information System (INIS)

    Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swelling and ion exchange properties of Hydrated 2:1 clay minerals, and the subsequent analysis and theoretical modeling with a view toward improving contaminant transport modeling as well as soil remediation and radionuclide containment strategies. Project results included the (a) development of simulation methods to treat clays under environmentally relevant conditions of variable water vapor pressure; (b) calculation of clay swelling thermodynamics as a function of interlayer ion size and charge (calculated quantities include immersion energies, free energies, and entropies of swelling); and (c) calculation of ion exchange free energies, including contributions from changing interlayer water contents and layer spacing

  1. New hydrated mineral detections in the ILDs of Valles Marineris: Insights into their aqueous history

    Science.gov (United States)

    Flahaut, J.; Bishop, J. L.; Fueten, F.; Quantin, C.; Thollot, P.; van Westrenen, W.; Davies, G. R.

    2014-04-01

    This paper presents a survey of the mineralogical diversity of the Interior Layered Deposits (ILDs) of Valles Marineris (VM) and Margaritifer Terra (MT) as determined with the highresolution hyperspectral imager CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) onboard MRO (Mars Reconnaissance Orbiter). A particular emphasis is made on localized detections of new hydrated phases within the dominantly sulfate-rich deposits. These detections are compared with other recent detections of unindentified minerals across the entire region [e.g. 10-19]. Characterizing the entire mineral assemblages at these sites is designed to provide more information on the chemistry of those complex aqueous deposits and their potential formation mechanism(s).

  2. Atomistic simulations of clay minerals subject to variably hydrated supercritical CO2

    Science.gov (United States)

    Glezakou, V.; Schaef, T.; McGrail, P.

    2012-12-01

    Commonly occurring clay minerals, such as phyllosilicates, tend to expand as they incorporate water. The ubiquitous presence and importance of clay minerals in caprock seals and shale gas plays undergoing enhanced gas recovery with CO2 requires much better understanding of chemically induced changes in these minerals upon contact with variably wet scCO2. Recent advances in our groups experimental techniques have enabled detailed characterization of the H2O/CO2 intercalation in a variety of montmorillonites. In parallel, we have also initiated density functional (DFT) simulations to help understand the interactions between layered materials and the water-bearing supercritical fluid alone or in the presence of sulfur-containing species, pertinent to mixed-gas injection conditions. Through our simulations, we expect to understand how CO2 interacts with different intra-layer ions under different degrees of hydration or the presence of sulfur-containing species, and how the overall swelling properties of the clays will be affected. Preliminary results indicate that clays with higher degrees of hydration are likely to expand more after CO2 intercalation, as illustrated in Figure 1.; Figure 1. Radial distribution function of Ca-C obtained from DFT-based molecular dynamics simulations of fully hydrated Ca2+ ions in supercritical CO2 show that the CO2 molecules will be found at average distances > 5 Å and can potentially induce higher degrees of swelling.

  3. Efflorescence as a source of hydrated sulfate minerals in valley settings on Mars

    Science.gov (United States)

    Szynkiewicz, Anna; Borrok, David M.; Vaniman, David T.

    2014-05-01

    A distinctive sulfur cycle dominates many geological processes on Mars and hydrated sulfate minerals are found in numerous topographic settings with widespread occurrences on the Martian surface. However, many of the key processes controlling the hydrological transport of sulfur, including sulfur sources, climate and the depositional history that led to precipitation of these minerals, remain unclear. In this paper, we use a model for the formation of sulfate efflorescent salts (Mg-Ca-Na sulfates) in the Rio Puerco watershed of New Mexico, a terrestrial analog site from the semiarid Southwest U.S., to assess the origin and environmental conditions that may have controlled deposition of hydrated sulfates in Valles Marineris on Mars. Our terrestrial geochemical results (?S34 of -36.0 to +11.1‰) show that an ephemeral arid hydrological cycle that mobilizes sulfur present in the bedrock as sulfides, sulfate minerals, and dry/wet atmospheric deposition can lead to widespread surface accumulations of hydrated sulfate efflorescences. Repeating cycles of salt dissolution and reprecipitation appear to be major processes that migrate sulfate efflorescences to sites of surface deposition and ultimately increase the aqueous SO42- flux along the watershed (average 41,273 metric tons/yr). We suggest that similar shallow processes may explain the occurrence of hydrated sulfates detected on the scarps and valley floors of Valles Marineris on Mars. Our estimates of salt mass and distribution are in accord with studies that suggest a rather short-lived process of sulfate formation (minimum rough estimate ?100 to 1000 years) and restriction by prevailing arid conditions on Mars.

  4. Photocatalytic Oxidation of Isoprene on Hydrated Atmospheric Mineral Dusts

    Science.gov (United States)

    Hoffmann, M. R.; Kameel, F. R.; Colussi, A. J.

    2011-12-01

    Mineral dust aerosols, an important fraction in the tropospheric aerosol budget, contain transition metal-based semiconductor particles that absorb light and may support diverse chemical transformations. Dust aerosol is primary, mostly originates from deserts, but includes fly ash emitted by power plants, and can be carried over long distances. We propose that such semiconductor particles may produce secondary organic aerosol (SOA) via surface-activated photochemical processes in aqueous media. Isoprene, the most abundant anthropogenic VOC is deemed to be incorporated into SOA by various mechanisms that remain to be fully characterized. We suggest that condensed-phase chemistry, in addition to gas-phase transformations, plays an important role in SOA formation. Isoprene is only slightly soluble in water, but it would react at diffusionally-controlled rates with photochemically generated OH-radicals in aqueous phase to produce more complex, polar compounds via oxidation and polymerization processes. We have found that the similar products are formed in the photolysis of aqueous hydrogen peroxide solutions or titanium dioxide suspensions in the presence of dissolved isoprene, as revealed by HPLC analysis with online high-resolution positive ion electrospray ionization mass spectrometric detection, and 1H and 13C nuclear magnetic resonance spectrometry. In contrast, hematite suspensions display negligible photocatalytic activity toward isoprene oxidation. These results suggest that atmospheric heterogeneous semiconductor photocatalysis of isoprene may play a significant role in global secondary organic aerosol formation under overly dusty conditions. Full product characterization is underway that aims at identifying species that may have adverse health/respiratory effects.

  5. Effects of electrolytes, soil and soil minerals on CH4 recovery from gas hydrates with CO2

    Science.gov (United States)

    Lee, N.; Lee, W.

    2012-12-01

    Large amount of natural gas hydrates, which are known as future energy source, are stored in permafrost regions and under subsea sediments. One of innovative CH4 recovery mechanism from clathrate hydrates is swapping CH4 molecules by CO2 in cage structure. It can provide not only a promising solution for scarcity of energy, also a carbon reduction method for global warming. Previous studies on swapping have been conducted majorly with pure gas hydrates and a little consideration of geochemical factors recently begins. For future application in real environment of CH4 and CO2 replacement process, thorough investigation on the effect of electrolytes, soil and soil minerals, which are coexisted with gas hydrates under deep-sea sediment, is required. In this study, for understanding the impact of changes of surrounding matters, recovery ratio of CH4 during swapping process is measured as time passed with electrolytes (NaCl, MgCl2, CaCl2, KCl), soil (soil, marine sediment) and soil minerals (montmorillonite, kaolinite, nontronite, pyrite) by gas chromatography (GC). Replacement rates between CH4 and CO2 of samples reach the maximum replacement rate which can occur with pure hydrates sample in the last, however the required time is varied according to samples. There is the tendency that takes more time with soil and soil minerals than others due to the hydrates which are placed in the structure of soil and soil minerals. The experimental results imply that electrolytes, soil and soil minerals have significant effects on CH4 recovery by CO2 in gas hydrates. It could be applicable to excavate CH4 from hydrate deposits and also store the CO2 in existed hydrates structures in the future.

  6. Adhesion of CO2 on hydrated mineral surfaces and its implications to geologic carbon sequestration

    Science.gov (United States)

    Wang, S.; Clarens, A. F.; Tao, Z.; Persily, S. M.

    2013-12-01

    Most mineral surfaces are water wetting, which has important implications for the transport of non-aqueous phase liquids, such as CO2, through porous media. In this work, contact angle experiments were carried out wherein unusual wetting behavior was observed between mineral surfaces and liquid or supercritical CO2 under certain geochemical conditions. This behavior can be understood in the context of adhesion between the CO2 and the mineral surface. When adhesion occurs, the wettability characteristics of the surfaces are significantly altered. More importantly, the CO2 exhibits a strong affinity for the surface and is highly resistant to shear forces in the aqueous phase. A static pendant drop method was used on a variety of polished mineral surfaces to measure contact angles. The composition of the aqueous phase (e.g., pH, ionic strength) and the characteristics of the mineral surface (e.g., composition, roughness), were evaluated to understand their impact on the prevalence of adhesion. Pressure and temperature conditions were selected to represent those that would be prevalent in geologic carbon sequestration (GCS) or during leakage from target repositories. Adhesion was widely observed on phlogopite mica, silica, and calcite surfaces with roughness on the order of ~10 nanometers. CO2 exhibited no adhesion on mineral surfaces with higher roughness (e.g., quartz). On smoother surfaces, the CO2 is thought to have more effective contact area with the mineral, enabling the weak van der Waals forces that drive most adhesion processes. Brine chemistry also had an important role in controlling CO2 adhesion. Increases in CO2 partial pressure and ionic strength both increased the incidence of adhesion. The addition of strong acid or strong base permanently inhibited the development of adhesion. These results suggest that the development of adhesion between the CO2 and the mineral surface is dependent on the integrity and thickness of the hydration layer between the CO2 and the mineral. N2 control experiments were carried out under the same pressure and temperature conditions and adhesion was also observed. The wettability hysteresis phenomena were quantified under adhesion conditions by means of advancing/receding contact angle measurements. The experimental results indicated that adhesion could cause an increase in the contact angle by a factor of three. These results support an emerging understanding of adhesion of nonpolar non-aqueous phase fluids on mineral surfaces influenced by the relative thickness of the electrical double layer embedded in the hydration layer between CO2 or N2 and the mineral surface. These findings could have important implications in certain geological formations for estimating residual trapping, capillary pressure, and a number of other processes that are strongly dependent on the wetting behavior of mineral surfaces. Keywords: geologic carbon sequestration, CO2 adhesion, hydration layer, wettability alteration and hysteresis, aqueous chemistry, surface roughness

  7. Acid-base balance and hydration status following consumption of mineral-based alkaline bottled water

    Directory of Open Access Journals (Sweden)

    Heil Daniel P

    2010-09-01

    Full Text Available Abstract Background The present study sought to determine whether the consumption of a mineral-rich alkalizing (AK bottled water could improve both acid-base balance and hydration status in young healthy adults under free-living conditions. The AK water contains a naturally high mineral content along with Alka-PlexLiquid?, a dissolved supplement that increases the mineral content and gives the water an alkalizing pH of 10.0. Methods Thirty-eight subjects were matched by gender and self-reported physical activity (SRPA, hrs/week and then split into Control (12 women, 7 men; Mean +/- SD: 23 +/- 2 yrs; 7.2 +/- 3.6 hrs/week SRPA and Experimental (13 women, 6 men; 22 +/- 2 yrs; 6.4 +/- 4.0 hrs/week SRPA groups. The Control group consumed non-mineralized placebo bottled water over a 4-week period while the Experimental group consumed the placebo water during the 1st and 4th weeks and the AK water during the middle 2-week treatment period. Fingertip blood and 24-hour urine samples were collected three times each week for subsequent measures of blood and urine osmolality and pH, as well as total urine volume. Dependent variables were analyzed using multivariate repeated measures ANOVA with post-hoc focused on evaluating changes over time within Control and Experimental groups (alpha = 0.05. Results There were no significant changes in any of the dependent variables for the Control group. The Experimental group, however, showed significant increases in both the blood and urine pH (6.23 to 7.07 and 7.52 to 7.69, respectively, a decreased blood and increased urine osmolality, and a decreased urine output (2.51 to 2.05 L/day, all during the second week of the treatment period (P Conclusions Consumption of AK water was associated with improved acid-base balance (i.e., an alkalization of the blood and urine and hydration status when consumed under free-living conditions. In contrast, subjects who consumed the placebo bottled water showed no changes over the same period of time. These results indicate that the habitual consumption of AK water may be a valuable nutritional vector for influencing both acid-base balance and hydration status in healthy adults.

  8. Hydrated Salt Minerals on Europa, Ganymede and Other Objects: Presence, Origin and Behavior

    Science.gov (United States)

    McCord, T. B.

    2002-12-01

    Hydrated salt minerals on the surface of Europe and Ganymede are reported from the Galileo mission. This discovery is important for it is related to the original composition and evolution of these satellites and probably is related to the presence and nature of liquid water deposits below the surface and their ability to sustain life. Thermal evolution models predict salts and suggest circulation of water through warm/hot materials on or below the ocean floor. Further, salt deposits are present in primitive meteorites, suggesting they are the result of a common process(es) and that they may be found on other outer solar system objects such as Saturn's satellites and Ceres, to be explored by the Cassini and DAWN missions, respectively. The evidence for hydrated salts is the distorted water absorptions present in the IR reflectance spectra. The physical location of these absorptions in the disrupted regions of Europa (lineaments and chaotic terrain) indicates an association with endogenic processes and the putative ocean below. These materials and their spectra provide chemical constraints on the nature of the ocean, especially if a detailed analysis could be obtained from orbit, a lander or returned samples. The presence of these salts on Ganymede is less evident than for Europa and suggests older deposits, perhaps related to a different evolution timescale. The behavior of hydrated salt minerals on the surfaces of these objects has been explored recently in the laboratory. The results indicate that some are more stable to thermal and radiative disruption than is water ice. They would survive for the age of the solar system and probably develop lag deposits due to preferential loss of water ice. Chemical models confirm these results. Finally, injection of brines into an Europa-like surface environment produces materials even more hydrated and with more Europa-like spectral characteristics than for more crystalline materials usually found under ambient terrestrial laboratory conditions. These salts provide direct evidence for liquid water below the surface that was/is hospitable to life.

  9. Hydrated-layer formation during dissolution of complex silicate glasses and minerals

    Science.gov (United States)

    Petit, J.-C.; Della Mea, G.; Dran, J.-C.; Magonthier, M.-C.; Mando, P. A.; Paccagnella, A.

    1990-07-01

    The characteristics of aqueous dissolution of three complex silicate glasses (rhyolitic, basaltic, and simulated nuclear-waste glass) have been investigated by analytical techniques based on energetic ion beams, which provide depth profiles of various elements including hydrogen, on the altered surface of the materials. The two main corrosion features of this type of glass have been extensively documented: the build-up of a hydrated layer and the surficial accumulation of transition and heavy elements. Comparison with the corrosion behavior of ion-bombarded silicate minerals and study of the influence of solution temperature (in the range 60-200°C) and chemistry (effect of high sodium concentration) allow a better understanding of the corrosion mechanism. It is shown that hydration involves two different processes simultaneously, namely ion exchange between hydrogen and glass network modifiers and permeation of molecular water, their respective importance depending markedly on temperature and solution chemistry. Heavy element accumulation is explained by the precipitation of hydroxides or complex hydrosilicates, the latter possibly resulting also from ion exchange with major cations of primary hydrosilicates.

  10. Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters

    International Nuclear Information System (INIS)

    Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled

  11. Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Roscoe, R.J.; Steenland, K.; Halperin, W.E.; Beaumont, J.J.; Waxweiler, R.J.

    1989-08-04

    Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled.

  12. Radiographic changes in a group of chrysotile miners and millers exposed to low asbestos dust concentrations.

    OpenAIRE

    Cordier, S.; Theriault, G.; Provencher, S.

    1984-01-01

    Radiographic changes in 342 Quebec asbestos miners exposed to low levels of asbestos dust for an average period of 20 years were studied. Their estimated cumulative exposure ranged from 7 fibres per cubic centimeter X years (f-y/cc) to 300 f-y/cc. Of these workers, 2.1% showed a small opacity score of 1/0 or more and 2.7% showed pleural changes. No linear relationship could be established between small opacity score and any index of exposure to asbestos. Pleural changes were related to age. A...

  13. Human Biomonitoring Data from Mercury Exposed Miners in Six Artisanal Small-Scale Gold Mining Areas in Asia and Africa

    Directory of Open Access Journals (Sweden)

    Jennifer Baeuml

    2011-11-01

    Full Text Available Objectives: In artisanal small-scale gold mining (ASGM areas in many developing countries, mercury (Hg is used to extract gold from ore. Data of 1250 participants from Indonesia, Mongolia, Philippines, Tanzania, and Zimbabwe were combined to analyze the relation between exposure in ASGM areas and body burden. Methods: Four groups were selected relating to their intensity of contact with mercury: (i a non-exposed control group; (ii a low exposed group with participants only living in mining areas, but not working as miners; (iii a medium exposed group, miners living in exposed areas and working with mercury without smelting amalgam; and (iv a high exposed group, miners living in exposed areas and smelting amalgam. Results: Compared to the non-exposed control group, participants living and/ or miners working in highly exposed areas have significantly higher concentration of total mercury in urine, hair and blood (p-value < 0.001. The median mercury value in urine in the control group is < 0.2 µg/L. In the high exposed group of amalgam smelters, the median in urine is 12.0 µg/L. The median in blood in the control group is < 0.93 µg/L. The median level in blood of the high exposed group is 7.56 µg/L. The median for mercury in hair samples from the control group is 0.21 µg/g. In the high exposed group the median hair concentration is 2.4 µg/g hair. Mercury levels also differ considerably between the countries, reflecting a diverse background burden due to different fish eating habits and different work place methods. Conclusions: A high percentage of exposed individuals had levels above threshold values. These high levels of mercury are likely to be related with serious health problems.

  14. Long-term effects of lead poisoning on bone mineralization in vultures exposed to ammunition sources

    International Nuclear Information System (INIS)

    Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron percnopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10-1780 ?g L-1n = 137; Iberian Peninsula range: 5.60-217.30 ?g L-1n = 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significantly altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant. - Bone lead accumulation decreases the degree of bone mineralization in vultures exposed to ammunition sources

  15. Polymer controlled mineralization of zinc phosphate hydrates and applications in corrosion protection, catalysis and biomedicine

    OpenAIRE

    Herschke, Laurent

    2004-01-01

    ABSTRACT Materials research devoted to the development of new or improved materials based on zinc phosphate hydrate cements with enhanced mechanical and chemical stability, suitable as “environmental friendly” corrosion inhibitor for partial or permanent restoration of bone and teeth attracts much interest at the interface between medicine, inorganic and physical chemistry and ceramic science. Reference probes, namely alpha-and beta-hopeite (i.e. a-, b-ZPT) have been synthesized...

  16. Lung cancer in Swedish iron miners exposed to low doses of radon daughters

    International Nuclear Information System (INIS)

    In a retrospective study, we investigated lung-cancer mortality from 1951 to 1976 in 1415 Swedish iron miners exposed to short-lived radioactive daughters of radon gas at concentrations leading to annual doses close to the currently accepted occupational limit. Fifty deaths from lung cancer were observed, as compared with 12.8 expected; expected rates were determined by a smoking-specific analysis based on data from a random sample of the Swedish male population. Among nonsmokers 18 deaths were observed, as compared with 1.8 expected; among current smokers and recent exsmokers 32 deaths were observed and 11.0 were expected. The effects of smoking and exposure to alpha radiation from radon daughters were nearly additive. Comparison of lung-cancer risk coefficients from this study and from other cohort studies of underground miners showed good agreement. Exposure to radon daughters is a major medical problem is underground metal mining, but our results also indicate that exposure to radon daughters at home accounts for an appreciable number of cases of lung cancer in the general population

  17. Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals

    Energy Technology Data Exchange (ETDEWEB)

    White, Gaye F.; Shi, Zhi; Shi, Liang; Wang, Zheming; Dohnalkova, Alice; Marshall, Matthew J.; Fredrickson, Jim K.; Zachara, John M.; Butt, Julea N.; Richardson, David; Clarke, Thomas A.

    2013-04-16

    The mineral respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes brought together inside a transmembrane porin to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system that contains methyl viologen as an internalised electron carrier has been used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally-located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, direct electron transfer from the interior through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The observed rates of conduction through the protein complex were 2 to 3 orders of magnitude higher than that observed in whole cells, demonstrating that direct electron exchange between MtrCAB and Fe(III) oxides is efficient enough to support in-vivo, anaerobic, solid phase iron respiration.

  18. Aesthesiometric threshold changes over the course of a workshift in miners exposed to hand-arm vibration.

    OpenAIRE

    Haines, T.; Chong, J.; Verrall, A. B.; Julian, J.; Bernholz, C.; Spears, R.; Muir, D. C.

    1988-01-01

    The objective of this study was to investigate whether aesthesiometric threshold changes occur over the course of a workshift in vibration exposed hard rock miners relative to workers unexposed to vibration during the shift. The subjects were 99 miners and 40 smelter workers; four subjects declined to participate and nine were excluded from the analysis because of apparent failure to comprehend the testing procedure. Two point discrimination and depth sense aesthesiometry were conducted at th...

  19. Phase Field Theory Modeling of CH4 and CO2 Fluxes from Exposed Natural Gas Hydrate Reserviors

    OpenAIRE

    Baig, Khuram

    2009-01-01

    Natural gas hydrates are widely distributed in sediments along continental margins, and harbor enormous amounts of energy. Gas hydrates are crystalline solids which occur when water molecules form a cage like structure around a non-polar or slightly polar (eg. CO2, H2S) molecule. These enclathrated molecules are called guest molecules and obviously have to fit into the cavities in terms of volume. Massive hydrates that outcrop the sea floor have been reported in the Gulf of Mexico (MacDonald,...

  20. PIXE analysis of mineral composition of alfalfa root-tip exposed to low pH or aluminum stress condition

    International Nuclear Information System (INIS)

    PIXE analysis was applied to study alteration of mineral composition (Al, P, K, and Cl) of alfalfa root-tip exposed to low pH or aluminum stress. These minerals were detectable using one or two pieces of root-tips. Short-term (within 4 h) decreases in K/P and Cl/P ratios were observed under low pH and aluminum stress conditions. However, degree of the decrease was not same. Differences in toxic effects of low pH and Al on the root-tip of alfalfa are discussed. (author)

  1. Immunoglobulin, lysozyme, alpha 2-macroglobulin and transferrin levels in miners exposed to 222Rn daughters in shale mines

    International Nuclear Information System (INIS)

    A group of 38 miners working in shale mines, exposed to daughter products of 222Rn were examined for levels of immunoglobulins (Ig), lysozyme (LYS), the transferrin (TRF) and alpha 2 macroglobulin (A 2M) in the serum, and for levels of IgA and LYS in the saliva. In comparison with controls of the same age the results revealed that almost all values were increased in the miners with the exception of salivary LYS, whose levels were significantly decreased. The duration of work underground was proved to play a role: the longer period the miners had worked underground, the higher the levels of IgG and IgA in relation to the controls of the corresponding age, while for IgM, LYS and A 2M decreased values were observed related to the period of work underground. The analysis of the distribution of the values revealed that in some tests (A 2M and TRF) significant changes only involved part of the miners' population. (author)

  2. Conspicuous assemblages of hydrated minerals from the H2O-MgSO4-CO2 system on Jupiter’s Europa satellite

    Science.gov (United States)

    Muñoz-Iglesias, Victoria; Prieto-Ballesteros, Olga; Bonales, Laura J.

    2014-01-01

    Water ice, hydrated salts, and other volatile ices such as carbon dioxide (CO2), have been detected by spectroscopy on Europa’s surface. Although the presence of other candidate compounds like clathrate hydrates have not yet been observed on the moon, the existence of water and carbon dioxide combined with low temperature and relatively high cryostatic pressure in the interior of the planetary body, favors their occurrence. In this study, the evolution of the H2O-MgSO4-CO2 system as a function of temperature, pressure and high salt concentration was investigated, focusing especially on the differences between the resulting mineral parageneses. CO2-clathrate formation and dissociation were examined by Raman spectroscopy in the presence of other hydrated phases crystallized from aqueous solutions rich in magnesium sulfate (MgSO4) at several concentrations (5, 17 and 30 wt%) from 268 to 290 K and pressures up to 60 bar. The CO2-clathrate experimental equilibrium line in this salty system is presented for both gas and liquid CO2 stability fields. During the heating process, the mineral assemblage of the system evolved differently depending on the salt concentration. At subsaturation (5 wt% of MgSO4), the CO2-clathrate co-existed with water ice from 268 to 272 K. However, when the initial sulfate concentration was 17 wt%, at a temperature above 269 K, no mineral phase was stable apart from CO2-clathrate. If the salt concentration of the system was supersaturated (30 wt%), CO2-clathrate co-existed with meriadianiite (MgSO4·11H2O) from 269 to 275 K. Subsequently, meridianiite was transformed into epsomite (MgSO4·7H2O) and continued crystallizing until 300 K. The evolution of the supersaturated solution at different heating rates was also evaluated in detail. In experiments with the fastest heating, the epsomite was not stabilized and the resulting aqueous solution became more concentrated than initially, promoting a clathrate dissociation at lower temperatures than expected. Volume changes due to mineral transformations and partial/total melting processes were assessed for the system and applied to Europa’s geology. Thus, assuming that this system is present in Europa’s interior, the evolution of the presumed fluids and mineral assemblages may have resulted in the generation of local stresses promoting resurfacing. Depending on the initial composition of the system, the percentage of volume change would imply a chaotic terrain formation, or cause faulting.

  3. Lung cancer risk among Czech miners exposed to radon related to histological types

    International Nuclear Information System (INIS)

    Long term exposure to radon and its progeny is one of the most important health problems. Epidemiological studies have demonstrated that exposure of miners to radon in a mine atmosphere can cause lung cancer. It has been recognized that lung cancer risk in uranium miners is associated with increased incidence of certain histological types, especially epidermoid and small cell. Recent results showed that the basic dependence of the relative risk for the two main histological types is linear with cumulative exposure. However, there is a suggestion that time and age modifiers of the dependence may be different for the two types. The aim of the study was firstly to verify the assumed differences in incidence of histological types of lung cancer for the studied cohort and general population and secondly to characterize the relation of histological types specific incidence to different exposure patterns. The study is based on data of the oldest Czechoslovak cohort, which belongs among the largest ones with the longest follow-up. The cohort includes 4320 former uranium miners who started their work in uranium mines in West Bohemia in the period 1948-59, and were working at least for 4 years and their complete personal and anamnestic data were available

  4. Results of cytogenetic examinations of miners exposed to radon in ore mines

    International Nuclear Information System (INIS)

    In this study the radon air concentrations and clastogenic effects at three ore mines located in central east Slovakia, the gold mine of Hodrusa-Hamre, talcum mine of Hnusta, and iron ore mine in Nizna Slana are compared with the chromosomal aberrations observed in a control group of healthy men which experienced underground work. A random sample of radon concentration measurements in houses was used for control. Significant differences in counts of aberrations of the chromosomal type in lymphocytes of smoker-miners of Nizna Slana as compared with counts of such aberrations in lymphocytes of a control group of similar age were found. A dependence of chromosomal aberration counts from the underground exposure to radon by multiple regression procedures could not be ascertained. The results indicated that confounding of such dependence by smoking might have taken place

  5. Epidemiologic studies of lung disease among miners exposed to increased levels of radon daughters

    International Nuclear Information System (INIS)

    The mortality of uranium miners from both lung cancer and other respiratory diseases is strongly dependent on exposure to radon daughters, cigarette smoking, and height. Lung cancer among 15 different mining groups was analyzed to determine what factors influence incidence and the induction-latent period. At low exposures or at low exposure rates, alpha radiation is more efficient in inducing lung cancer, producing an upward convex exposure-response curve. The induction-latent period is shortened by an increased age at the start of mining, by cigarette smoking, and by high exposure rates. For follow-up periods of 20 to 25 years, the incidence increases with age at the start of mining, with the magnitude of exposure, and with the amount of cigarette smoking. Instead of extrapolating downward from high exposures to estimate risk at low levels, it might be more appropriate to use cancer rates associated with background radiation as the lowest point on the exposure-response curve

  6. Aesthesiometric threshold changes over the course of a workshift in miners exposed to hand-arm vibration.

    Science.gov (United States)

    Haines, T; Chong, J; Verrall, A B; Julian, J; Bernholz, C; Spears, R; Muir, D C

    1988-01-01

    The objective of this study was to investigate whether aesthesiometric threshold changes occur over the course of a workshift in vibration exposed hard rock miners relative to workers unexposed to vibration during the shift. The subjects were 99 miners and 40 smelter workers; four subjects declined to participate and nine were excluded from the analysis because of apparent failure to comprehend the testing procedure. Two point discrimination and depth sense aesthesiometry were conducted at the beginning and at the end of the workshift in all digits of both hands excluding the thumbs. In addition to the use of a vibrating tool during the shift, age, digital temperature, signs of arm injury, presence of fingertip callus, and handedness were documented. In the analysis the difference between postshift and preshift readings was studied in relation to these variables, particularly exposure to the jackleg drill during the shift. With the exception of exposure of the jackleg drill, no associations were observed between these variables and change over the workshift in aesthesiometric results, on both unadjusted comparison of means and backward elimination regression analysis. A statistically significant association, however, was found between the use of a jackleg drill and change in two point discrimination and in depth sense aesthesiometric results over the course of the shift, for the right hand. Evidence of the occurrence of a learning effect, particularly for two point discrimination aesthesiometry, was observed. The occurrence of an effect in the right, but not the left, hand reflects dominant handedness and relatively greater vibration exposure in the right hand in our subjects. This study supports the incorporation of an exposure free interval before aesthesiometric testing of vibration exposed workers. PMID:3342191

  7. Carbonation of Clay Minerals Exposed to scCO2/Water at 200 degrees and 250 degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T.; Ecker, L.; Gill, S.; Butcher, T.(BNL); Bour, D. (AltaRock Energy, Inc.)

    2010-11-01

    To clarify the mechanisms of carbonation of clay minerals, such as bentonite, kaolinite, and soft clay, we exposed them to supercritical carbon dioxide (scCO2)/water at temperatures of 200 and 250 C and pressures of 1500 and 2000 psi for 72- and 107-hours. Bentonite, comprising three crystalline phases, montmorillonite (MMT), anorthoclase-type albite, and quartz was susceptible to reactions with ionic carbonic acid yielded by the interactions between scCO2 and water, particularly MMT and anorthoclase-type albite phases. For MMT, the cation-exchangeable ions, such as Na+ and Ca2+, present in its basal interplanar space, were replaced by proton, H+, from ionic carbonic acid; thereafter, the cations leaching from MMT directly reacted with CO32- as a counter ion of H+ to form carbonate compounds. Such in-situ carbonation process in basal space caused the shrinkage and breakage of the spacing structure within MMT. In contrast, the wet carbonation of anorthoclase-type albite, categorized as rock minerals, entailed the formation of three amorphous by-products, such as carbonates, kaolinite-like compounds, and silicon dioxide. Together, these two different carbonations caused the disintegration and corruption of bentonite. Kaolinite clay containing the amorphous carbonates and silicon dioxide was inert to wet carbonation. We noted only a gain in weight due to its water uptake, suggesting that kaolinite-like by-products generated by the wet carbonation of rock minerals might remain unchanged even during extended exposure. Soft clay consisting of two crystalline phases, dolomite and silicon dioxide, also was unaltered by wet carbonation, despite the uptake of water.

  8. Automated processing of planetary hyperspectral datasets for the extraction of weak mineral signatures and applications to CRISM observations of hydrated silicates on Mars

    Science.gov (United States)

    Carter, J.; Poulet, F.; Murchie, S.; Bibring, J. P.

    2013-02-01

    Near infrared imaging spectrometers are key tools to investigate planetary surfaces in the Solar System. By coupling spectral and spatial information, they give access to the composition and morphology of the planets' surfaces which in turn provide insight into the geological state and history of the body. Processing and interpreting their datasets is however challenging owing to the very large amount of data they produce, a small subset of which contain relevant information, but also to numerous sources of errors, due to the instruments themselves or to observational biases, which further complicate the extraction of interesting but subtle spectral features. Collectively, these limitations have motivated the development of a set of tools that tackle these issues to facilitate the extraction of mineralogical information. The tools described here are successfully applied to the CRISM imaging spectrometer orbiting Mars in the search for hydrated silicates. An automated extraction of the hydrated silica signatures is performed at high accuracy and the discovery of a new mineral on Mars, epidote, is reported thanks to these new data reduction and analysis strategies.

  9. Dosimetric property of mineral extracted from calamari and exposed to gamma rays

    International Nuclear Information System (INIS)

    Dosimetric property of polymineral fraction, quartz mainly, obtained from calamari was investigated. The commercial calamari samples from China and Sud Africa were collected in the markets of Italy. All polymineral debris were extracted and isolated from the whole body of calamari. The surface of the polymineral samples was analyzed by using the Scanning Electron Microscopy (SEM) and their chemical composition was determined using Energy Dispersive Spectroscopy (EDS). The polymineral was exposed to gamma rays (60Co) at different doses (0.5-80 Gy) to determine dosimetric property. Thermoluminescent (TL) glow curves showed two peaks centered at around 98-100 °C and 128-138 °C temperature range. The glow curves have been analyzed by using a deconvolution program. A linear dose response between 0.5 to 20 Gy was observed. The TL response of the samples as a function of the time storage, fading, presented a reduction of about 36-40 % at the end of 24 h. The reproducibility of the TL response after ten cycles of irradiation-readout showed an acceptable standard deviation in dosimetry. The polimineral fraction obtained from calamari shows an interesting dosimetric property and it may be useful for dosimetry in gamma radiation field

  10. Mineral-microbial interaction in long term experiments with sandstones and reservoir fluids exposed to CO2

    Science.gov (United States)

    Kasina, Monika; Morozova, Daria; Pellizzari, Linda; Würdemann, Hilke

    2013-04-01

    Microorganisms represent very effective geochemical catalysts, and may influence the process of the CO2 storage significantly. The goal of this study is to characterize the interactions between minerals and microorganisms during their exposure to the CO2 in a long term experiment in high pressure vessels to better understand the influence of biological processes on the composition of the reservoir sandstones and the long term stability of CO2 storage. The natural gas reservoir, proposed for the CO2 storage is characterized by high salinity (up to 420 g/l) and temperatures around 130°C, at depth of approximately 3.5 km. Microbial community of the reservoir fluid samples was dominated by different H2-oxidising, thiosulfate-oxidising and biocorrosive thermophilic bacteria as well as microorganisms similar to representatives from other deep environments, which have not previously been cultivated. The cells were attached to particles and were difficult to detect because of low cell numbers (Morozova et al., 2011). For the long term experiments, the autoclaved rock core samples from the core deposit were grinded, milled to the size of 0.5 mm and incubated with fresh reservoir fluids as inoculum for indigenous microorganisms in a N2/CH4/H2-atmosphere in high pressure vessels at a temperature of 80°C and pressure of 40 bars. Incubation was performed under lower temperature than in situ in order to favor the growth of the dormant microorganisms. After three months of incubation samples were exposed to high CO2 concentrations by insufflating it into the vessels. The sampling of rock and fluid material was executed 10 and 21 months after start of the experiment. Mineralogical analyses performed using XRD and SEM - EDS showed that main mineral components are quartz, feldspars, dolomite, anhydrite and calcite. Chemical fluid analyses using ICP-MS and ICP-OES showed that after CO2 exposure increasing Si4+ content in the fluid was noted after first sampling (ca. 25 relative %), whereas after the second sampling it decreased (to 31 relative %) in comparison to the reservoir fluid sample. This may suggest dissolution of silicate minerals at first, and secondary precipitation at second stage of experiment. In addition, immobilization of heavy metals dispersed within silicate minerals was also detected. An increase of Ca (3.2 up to 13% relative), SO4 (up to 14 relative %) and Fetot (47 and 24% relative) were also detected after first and second sampling respectively and may suggest dissolution of cements and iron rich minerals. The concentration of organic acids increased relatively by 12.5 % and 25% after first and second sampling respectively might be an indication for metabolic activity of microorganism or an effect of mobilisation due to CO2 exposure. The presence of newly formed mineral phases was detected using SEM-EDS. Quartz, albite and illite precipitation is a common process in all studied samples. However only illite is considered to be of bacterial origin, nevertheless its crystallization can also occur as a consequence of inorganic diagenetic processes. Further analyses of the microbial community composition, quantity and activity will bring a more insight into the CO2 exposure processes. Daria Morozova, Dagmar Kock, Martin Krüger, and Hilke Würdemann. Biogeochemical and microbial characterization of reservoir fluids from a gas field (Altmark). Geotechnologien 2011

  11. Simulation of hydrate dynamics in reservoirs

    OpenAIRE

    Kvamme, Bjørn; Vafaei, Mohammad Taghi; Chejara, Ashok; Jemai, Khaled

    2011-01-01

    Gas hydrates in reservoirs are generally not in thermodynamic equilibrium and there may be several competing phase transitions involving hydrate. Formation of carbon dioxide hydrates during aquifer storage of carbon dioxide involves roughly 10% volume increase compared to groundwater. Dissociation of hydrate towards under saturated fluid phases involves the same level of contraction. Hydrate phase transitions are generally fast (scales of seconds) compared to mineral dissolutio...

  12. New french uranium mineral species

    International Nuclear Information System (INIS)

    In this work, the authors study the french new uranium minerals: parsonsite and renardite, hydrated phosphates of lead and uranium; kasolite: silicate hydrated of uranium and lead uranopilite: sulphate of uranium hydrated; bayleyite: carbonate of uranium and of hydrated magnesium; ? uranolite: silicate of uranium and of calcium hydrated. For all these minerals, the authors give the crystallographic, optic characters, and the quantitative chemical analyses. On the other hand, the following species, very rare in the french lodgings, didn't permit to do quantitative analyses. These are: the lanthinite: hydrated uranate oxide; the ? uranotile: silicate of uranium and of calcium hydrated; the bassetite: uranium phosphate and of hydrated iron; the hosphuranylite: hydrated uranium phosphate; the becquerelite: hydrated uranium oxide; the curite: oxide of uranium and lead hydrated. Finally, the authors present at the end of this survey a primary mineral: the brannerite, complex of uranium titanate. (author)

  13. Minerals

    Directory of Open Access Journals (Sweden)

    Vaquero, M. P.

    1998-08-01

    Full Text Available The possible changes in the mineral composition of food during frying could be the consequence of losses by leaching, or changes in concentrations caused by exchanges between the food and culinary fat of other compounds. The net result depends on the type of food, the frying fat used and the frying process. Moreover, the modifications that frying produces in other nutrients could indirectly affect the availability of dietary minerals. The most outstanding ones are those that can take place in the fat or in the protein. With respect to the interactions between frying oils and minerals, we have recent knowledge concerning the effects of consuming vegetable oils used in repeated fryings of potatoes without turnover, on the nutritive utilization of dietary minerals. The experiments have been carried out in pregnant and growing rats, which consumed diets containing, as a sole source of fat, the testing frying oils or unused oils. It seems that the consumption of various frying oils, with a polar compound content lower or close to the maximum limit of 25% accepted for human consumption, does not alter the absorption and metabolism of calcium, phosphorous, iron or copper. Magnesium absorption from diets containing frying oils tends to increase but the urinary excretion of this element increases, resulting imperceptible the variations in the magnesium balance. The urinary excretion of Zn also increased although its balance remained unchanged. Different studies referring to the effects of consuming fried fatty fish on mineral bioavailability will also be presented. On one hand, frying can cause structural changes in fish protein, which are associated with an increase in iron absorption and a decrease in body zinc retention. The nutritive utilization of other elements such as magnesium, calcium and copper seems to be unaffected. On the other hand; it has been described that an excess of fish fatty acids in the diet produces iron depletion, but when fatty fish is fried in olive oil the quality of the fish oil improves, enhancing the nutritive utilization of iron and other dietary minerals.

  14. Estudio comparativo de los efectos de Hidrato de Cloral y Etanol en ratas expuestas a Fluoracetato de Sodio / Comparative study of the effects of cloral hydrate and ethanol in rats exposed to sodium fluoracetate

    Scientific Electronic Library Online (English)

    Jenni L, Ramírez M; Manuel S, Ramírez S; Elsa Y, Gutiérrez R; Francisco, Mujica.

    2012-12-01

    Full Text Available El fluoroacetato de sodio, es un raticida prohibido en algunos países y permitido en otros, que causa severas intoxicaciones humanas y animales. Actúa por inhibición del ciclo de Krebs e interfiere con la producción de energía, lo cual conduce a disfunción celular irreversible, especialmente en sist [...] ema nervioso central y corazón. El alcohol etílico, debido a su oxidación a acido acético y a su amplia disponibilidad, es uno de los fármacos usados en esta intoxicación, lo que podría causar controversias éticas y legales. La biotransformación del hidrato de cloral a tricloroetanol y a ácido tricloroacético, el efecto anticonvulsivante y su amplio uso en Pediatría, fueron las razones para su evaluación en la intoxicación por fluoroacetato. Se realizó un estudio experimental, para comparar los efectos de hidrato de cloral y alcohol en ratas intoxicadas con fluoroacetato de sodio. El análisis estadístico aplicado fue la prueba de chi cuadrado. Los resultados mostraron que el hidrato de cloral a dosis bajas, permite la sobrevivencia en 100% de los animales expuestos. Se confirmó igualmente la efectividad del alcohol etílico a dosis altas. Este resultado sugiere que el hidrato de cloral puede ser una opción tan útil como el etanol y que podría ser el fármaco de elección en aquellos pacientes que no puedan recibir monoacetin o etanol o porque haya mayor accesibilidad al hidrato de cloral. Abstract in english Sodium fluoroacetate is a banned rodenticide in some countries and allowed in others, which causes severe human and animal poisonings. It acts for inhibition of Krebs's cycle and interferes with energy production leading to irreversible cellular dysfunction, specially in nervous central system and h [...] eart. Ethyl alcohol, because oxidation to acetic acid and to its wide availability, is one of the drugs used in this poisoning, which should can cause ethical and legal controversies. Biotransformation of chloral hydrate to trichloroethanol and trichloroacetic acid, the anticonvulsant effect and its widespread use in Pediatrics, were the reasons for its evaluation in fluoroacetate poisoning. An experimental study was conducted, to compare effects of chloral hydrate and ethanol in poisoned rats with sodium fluoroacetate. The statistical analysis applied was the chi square test. The results showed that chloral hydrate in low doses allows survival in 100 % of the exposed animals. It also confirms the effectiveness of ethyl alcohol at high doses. This result suggests that chIoral hydrate may be an option as useful as ethanol and could be the choice drug in those patients who could not receive monoacetin or ethanol or because there is greater accessibility to chloral hydrate.

  15. Human Biomonitoring Data from Mercury Exposed Miners in Six Artisanal Small-Scale Gold Mining Areas in Asia and Africa

    OpenAIRE

    Jennifer Baeuml; Stephan Bose-O’Reilly; Raffaella Matteucci Gothe; Beate Lettmeier; Gabriele Roider; Gustav Drasch; Uwe Siebert

    2011-01-01

    Objectives: In artisanal small-scale gold mining (ASGM) areas in many developing countries, mercury (Hg) is used to extract gold from ore. Data of 1250 participants from Indonesia, Mongolia, Philippines, Tanzania, and Zimbabwe were combined to analyze the relation between exposure in ASGM areas and body burden. Methods: Four groups were selected relating to their intensity of contact with mercury: (i) a non-exposed control group; (ii) a low exposed group with participants only living in minin...

  16. Bone mineral density and polymorphisms in metallothionein 1A and 2A in a Chinese population exposed to cadmium

    International Nuclear Information System (INIS)

    Cadmium (Cd) effect on bone varies between individuals. We investigated whether genetic variation in metallothionein (MT)1A and MT2A associated with Cd induced bone loss in this study. A total of 465 persons (311 women and 154 men), living in control, moderately and heavily polluted areas, participated. The participants completed a questionnaire and the bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of Cd in urine (UCd) and blood (BCd). Genotypes for polymorphisms in MT1A (rs11076161) and MT2A (rs10636) were determined by Taqman allelic discrimination assays. BCd had a weak association with variant alleles for MT1A (rs11076161) and MT2A (rs10636) in female living in the highly polluted group (p = 0.08 and 0.05, respectively). A weak association was found between bone mineral density and MT2A polymorphisms variation (p = 0.06) in female living in the highly polluted group. Only a weak association was found between bone mineral density and MT1A polymorphisms variation in female. Genetic variation in the MT1A and MT2A genes may not associate with bone loss caused by cadmium exposure. - Highlights: ? We investigated the association between metallothionein polymorphisms bone mineral density. ? MT1A and MT2A polymorphisms showed a weak association with cadmium in blood. ? MT1A and MT2A polymorphisms showed no association with bone mineral denno association with bone mineral density.

  17. Hidden shift of the ionome of plants exposed to elevated CO2 depletes minerals at the base of human nutrition

    OpenAIRE

    Loladze, Irakli

    2014-01-01

    Mineral malnutrition stemming from undiversified plant-based diets is a top global challenge. In C3 plants (e.g., rice, wheat), elevated concentrations of atmospheric carbon dioxide (eCO2) reduce protein and nitrogen concentrations, and can increase the total non-structural carbohydrates (TNC; mainly starch, sugars). However, contradictory findings have obscured the effect of eCO2 on the ionome—the mineral and trace-element composition—of plants. Consequently, CO2-induced shifts in plant ...

  18. Hidden shift of the ionome of plants exposed to elevated CO2 depletes minerals at the base of human nutrition.

    Science.gov (United States)

    Loladze, Irakli

    2014-01-01

    Mineral malnutrition stemming from undiversified plant-based diets is a top global challenge. In C3 plants (e.g., rice, wheat), elevated concentrations of atmospheric carbon dioxide (eCO2) reduce protein and nitrogen concentrations, and can increase the total non-structural carbohydrates (TNC; mainly starch, sugars). However, contradictory findings have obscured the effect of eCO2 on the ionome-the mineral and trace-element composition-of plants. Consequently, CO2-induced shifts in plant quality have been ignored in the estimation of the impact of global change on humans. This study shows that eCO2 reduces the overall mineral concentrations (-8%, 95% confidence interval: -9.1 to -6.9, p carbon:minerals in C3 plants. The meta-analysis of 7761 observations, including 2264 observations at state of the art FACE centers, covers 130 species/cultivars. The attained statistical power reveals that the shift is systemic and global. Its potential to exacerbate the prevalence of 'hidden hunger' and obesity is discussed.DOI: http://dx.doi.org/10.7554/eLife.02245.001. PMID:24867639

  19. Effect of epimedium pubescen flavonoid on bone mineral status and bone turnover in male rats chronically exposed to cigarette smoke

    Directory of Open Access Journals (Sweden)

    Gao Shu-guang

    2012-06-01

    Full Text Available Abstract Background Epimedii herba is one of the most frequently used herbs in formulas that are prescribed for the treatment of osteoporosis in China and its main constituent is Epimedium pubescen flavonoid (EPF. However, it is unclear whether EPF during chronic exposure to cigarette smoke may have a protective influence on the skeleton. The present study investigated the effect of EPF on bone mineral status and bone turnover in a rat model of human relatively high exposure to cigarette smoke. Methods Fifty male Wistar rats were randomized into five groups: controls, passive smoking groups and passive smoking rats administered EPF at three dosage levels (75, 150 or 300?mg/kg/day in drinking water for 4?months. A rat model of passive smoking was prepared by breeding male rats in a cigarette-smoking box. Bone mineral content (BMC, bone mineral density (BMD, bone turnover markers, bone histomorphometric parameters and biomechanical properties were examined. Results Smoke exposure decreased BMC and BMD, increased bone turnover (inhibited bone formation and stimulated its resorption, affected bone histomorphometry (increased trabecular separation and osteoclast surface per bone surface; decreased trabecular bone volume, trabecular thickness, trabecular number, cortical thickness, bone formation rate and osteoblast surface per bone surface, and reduced mechanical properties. EPF supplementation during cigarette smoke exposure prevented smoke-induced changes in bone mineral status and bone turnover. Conclusion The results suggest that EPF can prevent the adverse effects of smoke exposure on bone by stimulating bone formation and inhibiting bone turnover and bone resorption.

  20. Influence of minerals on lead-induced alterations in liver function in rats exposed to long-term lead exposure

    Energy Technology Data Exchange (ETDEWEB)

    Herman, D' souza Sunil, E-mail: hermansdsouza@rediffmail.com [Department of Biotechnology, Manipal Life Sciences Centre, KMC, Manipal University, Manipal (India); Geraldine, Menezes, E-mail: gere1@rediffmail.com [Department of Biochemistry and Biophysics, St. John' s Medical College, Koramangala, Bangalore 560034, Karnataka (India); T, Venkatesh, E-mail: venky_tv@hotmail.com [Department of Biochemistry and Biophysics, St. John' s Medical College, Koramangala, Bangalore 560034, Karnataka (India)

    2009-07-30

    The objective of this study was to evaluate the role of minerals on lead-induced effect on the liver. Differentiation of minerals and heavy metals pose an inherent problem due to certain common properties shared by them. With this approach to the problem of heavy metal toxicity, in the present study two groups of male Wistar albino rats, one group (well-nourished) fed on mineral rich diet and other group (undernourished) fed on diet without mineral supplements were used. Both the groups of rats were subjected to long-term lead exposure. The diet of well-nourished group was supplemented with calcium (Ca); 1.2%, phosphorous (P); 0.6%, iron (Fe); 90 mg/kg, zinc (Zn); 50 mg/kg, magnesium (Mg); 0.08%, manganese (Mn); 70 mg/kg, selenium (Se); 0.2 mg/kg, copper (Cu); 5 mg/kg, molybdenum (Mo); 0.8 mg/kg, iodine (I); 0.6 mg/kg, cobalt (Co); 3.0 mg/kg. Their blood lead and parameters of liver function were monitored periodically. Results of the study showed a very high statistically significant increase (p < 0.001) in the blood lead (PbB) levels and liver function test parameters in the undernourished subjects compared to the well-nourished subjects. Nutritional management of lead poisoning is of importance since essential elements and toxic heavy metals may interact to minimize the absorption of lead.

  1. Influence of minerals on lead-induced alterations in liver function in rats exposed to long-term lead exposure

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the role of minerals on lead-induced effect on the liver. Differentiation of minerals and heavy metals pose an inherent problem due to certain common properties shared by them. With this approach to the problem of heavy metal toxicity, in the present study two groups of male Wistar albino rats, one group (well-nourished) fed on mineral rich diet and other group (undernourished) fed on diet without mineral supplements were used. Both the groups of rats were subjected to long-term lead exposure. The diet of well-nourished group was supplemented with calcium (Ca); 1.2%, phosphorous (P); 0.6%, iron (Fe); 90 mg/kg, zinc (Zn); 50 mg/kg, magnesium (Mg); 0.08%, manganese (Mn); 70 mg/kg, selenium (Se); 0.2 mg/kg, copper (Cu); 5 mg/kg, molybdenum (Mo); 0.8 mg/kg, iodine (I); 0.6 mg/kg, cobalt (Co); 3.0 mg/kg. Their blood lead and parameters of liver function were monitored periodically. Results of the study showed a very high statistically significant increase (p < 0.001) in the blood lead (PbB) levels and liver function test parameters in the undernourished subjects compared to the well-nourished subjects. Nutritional management of lead poisoning is of importance since essential elements and toxic heavy metals may interact to minimize the absorption of lead.

  2. Bone mineral density and polymorphisms in metallothionein 1A and 2A in a Chinese population exposed to cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiao [Department of Bone Metabolism, Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Lei, Lijian [Department of Occupation Health, School of Public Health, Fudan University, Shanghai 200032 (China); Department of Epidemiology, School of Public Health, Shanxi Medical University, Shanxi 030001 (China); Tian, Liting [Department of Occupation Health, School of Public Health, Fudan University, Shanghai 200032 (China); Zhu, Guoying, E-mail: chx_win@hotmail.com [Department of Bone Metabolism, Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Jin, Taiyi, E-mail: tyjin@shmu.edu.cn [Department of Occupation Health, School of Public Health, Fudan University, Shanghai 200032 (China)

    2012-04-15

    Cadmium (Cd) effect on bone varies between individuals. We investigated whether genetic variation in metallothionein (MT)1A and MT2A associated with Cd induced bone loss in this study. A total of 465 persons (311 women and 154 men), living in control, moderately and heavily polluted areas, participated. The participants completed a questionnaire and the bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of Cd in urine (UCd) and blood (BCd). Genotypes for polymorphisms in MT1A (rs11076161) and MT2A (rs10636) were determined by Taqman allelic discrimination assays. BCd had a weak association with variant alleles for MT1A (rs11076161) and MT2A (rs10636) in female living in the highly polluted group (p = 0.08 and 0.05, respectively). A weak association was found between bone mineral density and MT2A polymorphisms variation (p = 0.06) in female living in the highly polluted group. Only a weak association was found between bone mineral density and MT1A polymorphisms variation in female. Genetic variation in the MT1A and MT2A genes may not associate with bone loss caused by cadmium exposure. - Highlights: Black-Right-Pointing-Pointer We investigated the association between metallothionein polymorphisms bone mineral density. Black-Right-Pointing-Pointer MT1A and MT2A polymorphisms showed a weak association with cadmium in blood. Black-Right-Pointing-Pointer MT1A and MT2A polymorphisms showed no association with bone mineral density.

  3. Bone mineral density and polymorphisms in metallothionein 1A and 2A in a Chinese population exposed to cadmium.

    Science.gov (United States)

    Chen, Xiao; Lei, Lijian; Tian, Liting; Zhu, Guoying; Jin, Taiyi

    2012-04-15

    Cadmium (Cd) effect on bone varies between individuals. We investigated whether genetic variation in metallothionein (MT)1A and MT2A associated with Cd induced bone loss in this study. A total of 465 persons (311 women and 154 men), living in control, moderately and heavily polluted areas, participated. The participants completed a questionnaire and the bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of Cd in urine (UCd) and blood (BCd). Genotypes for polymorphisms in MT1A (rs11076161) and MT2A (rs10636) were determined by Taqman allelic discrimination assays. BCd had a weak association with variant alleles for MT1A (rs11076161) and MT2A (rs10636) in female living in the highly polluted group (p=0.08 and 0.05, respectively). A weak association was found between bone mineral density and MT2A polymorphisms variation (p=0.06) in female living in the highly polluted group. Only a weak association was found between bone mineral density and MT1A polymorphisms variation in female. Genetic variation in the MT1A and MT2A genes may not associate with bone loss caused by cadmium exposure. PMID:22391096

  4. CO2 Injection in Hydrate Bearing Sandstone with Excess Water

    OpenAIRE

    Ha?genvik, Christian

    2013-01-01

    It has previously been shown that methane can be produced from gas hydrates by exposing it to carbon dioxide. Since CO2 is the preferred hydrate former below 10 °C it will spontaneously replace CH4 as the guest molecule in the hydrate without introducing heat. This production method is beneficial because it offers long term storage of CO2 with the added benefit of produced methane without dissociating the hydrate. Previous experimental research on production from gas hydrates by CO2 injec...

  5. Epidemiological study of radon-exposed mineral mine workers in north east Bavaria including chromosome dosimetric method

    International Nuclear Information System (INIS)

    360 hard-rock miners were examined for breathing organ health, working conditions, smoking habits, and partly for chromosome aberrations (115 persons, 100 cells each). Long-time exposure at diameter 1 to 4 WL Rn-daughters and/or occasional >= 1000 pCi Rn/l air increased rates of S2-type aberrations (x 3,4; P 2-rates. From dose estimations, bronchial radiation conditions appear as bronchitis cofactor; lymphocyte but not lymph node dose fairly fits S2-rate after 20 years' exposure. (orig.)

  6. Prevalence of hepatitis B and C virus markers among malaria-exposed gold miners in Brazilian Amazon

    Scientific Electronic Library Online (English)

    Francisco José Dutra, Souto; Cor Jésus Fernandes, Fontes; Ana Maria Coimbra, Gaspar.

    2001-08-01

    Full Text Available SciELO Brazil | Language: English Abstract in english Hepatitis B and C virus markers were assessed during a survey on malaria in gold mine camps in southern Brazilian Amazon in order to identify risk factors associated to these viral diseases. The study comprised 520 subjects, most of them were gold miners. Missing subjects totaled 49 (8.6%). Among th [...] ese 520, 82.9% had HBV markers and 7.1% were HBsAg positive. Previous hospitalization, surgery, sexually transmitted diseases and incarceration were quite common among surveyed people, but there is no association between total HBV markers and these factors. On other hand, HBsAg was independently associated to history of sexually transmitted diseases and history of surgery after adjustment. The most frequent HBsAg subtypes identified, adw2 (59%), predominates in populations of Northeast Brazil. The most surveyed people were immigrants coming from that area suggesting that immigrants carried HBV themselves to the study area. Immunoblot (RIBA) confirmed-anti-HCV were found in 2.1%. The only variable associated to anti-HCV in multivariate analysis was illicit intravenous drug. Lack of HCV infection in subjects with such a high HBV markers prevalence reinforces the opinion that HCV is transmitted by restricted routes when compared to HBV. Furthermore, gold miners in Amazon may be considered as a risk group for HBV infection, but not for HCV.

  7. CHANGES IN LEVELS OF ANTIOXIDANT MINERALS AND VITAMINS IN WISTAR MALE RATS EXPOSED TO METHIONINE CONTAINING ACETAMINOPHEN FORMULATION

    Directory of Open Access Journals (Sweden)

    Adeniyi Francis A. A.

    2011-05-01

    Full Text Available This study was carried out to determine the effect of toxic and subtoxic doses of acetaminophen on antioxidant vitamins and minerals in male Wistar rats. Five groups served as the test groups and received different doses of the acetaminophenmethionine formulation in ratio 9:1. The sixth group served as the control and received only the vehicle: physiologic saline. At the end of 24 hours of exposure, blood was obtained from each rat through retro-orbital bleeding, the levels of antioxidant vitamins and minerals were determined using high-performance liquid chromatography and atomic absorption spectrophotometric technique. Results showed that at 100 mg/kg BW level of exposure, niacin, vitamin A, vitamin E, zinc, copper, manganese, selenium were significantly increased (p0.05 compared with controls. At both 350 and 1000 mgkg BW levels of exposure, all these antioxidant indices were significantly decreased (p0.05 at 350 mgkg BW (body weight level of exposure compared with the control group. The animals in 3000 mgkg BW and 5000 mgkg groups suffered 40% and 100% mortality respectively by the end of the 24th hour. This study therefore showed that acetaminophenmethionine formulation in the ratio of 9:1 may cause alteration of vital elements and biomolecules not only at toxic levels but also at tolerable level of 100 mgkg BW.

  8. Calcium Aluminate Cement Hydration Model

    Directory of Open Access Journals (Sweden)

    Matusinovi?, 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 (?=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 (? < 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. (18, the interaction at phase boundary was described by a bimolecular consumption of both reactants (eq. (19, cement and free water, while the mass transfer mechanism was described relative to the limiting reactant (eq. (21.Increasing temperature from 5 to 20 °C decreases the rate of nucleation and growth (NR (Fig. 6, increases the rate of interaction (I according to Arrhenius law (E12 ?43 kJ mol-1 (Fig. 7, and increases the rate of mass transfer (k linearly (Fig. 8.

  9. Effect of the Curcumin Supplementation on the Regional Bone Mineral Density of Femur and Tibial Bones in Young Rats Exposed to Lead Acetate

    Directory of Open Access Journals (Sweden)

    Dabidi Roshan Valiollah

    2011-07-01

    Full Text Available Background and Objective: Recent studies have shown that lead causes oxidative stress in bones by inducing the generation of reactive oxygen species. In this study, the effects of 8-week curcumin supplementation on the regional bone mineral density of femur and tibial bones in rats exposed to lead acetate was investigated. Materials and Method: Fifty days aged Wistar rats were randomly assigned to baseline, sham-operate, lead acetate and curcumin + lead (curcumin groups. Lead and/or curcumin groups received 20 mg/kg lead acetate peritoneally for 8 weeks (3 days/week. In addition, the curcumin group received 30 mg/kg curcumin solution for 3 days-a-week for 8 weeks. The femur and tibial BMD were measured by Dual-Energy X-Ray Absorptiometry (DEXA methods. Data was analyzed by one-way ANOVA test and SPSS 17. Results: MDA and lead levels were significantly lower in the curcumin group compared with lead-exposed and baseline groups. In addition, BMD and TAC levels was significantly higher in the curcumin group compared with lead-treated and baseline groups. Conclusion: These results show that environmental exposure to lead may be a risk factor for skeletal diseases. Furthermore, the curcumin supplementation possibly has inhibitory effects on lead-induced loss of femur and tibial BMD. Sci Med J 2011; 10(3:295-307

  10. Evaluation of the mortality standard of a miners cohort exposed to radon in an underground coal mining, Parana, Brazil

    International Nuclear Information System (INIS)

    This study aims to to evaluate the possible health effects on workers in a underground coal mining that were exposed to radon and its decay products without the knowledge of the exposure risk. We established a historical cohort of workers in this mining which included 2856 workers, 1946 underground workers and 910 surface workers, and was carried out a retrospective tracking of mortality in this cohort between 1979 and 2002. Through multiple strategies for monitoring, involving several national institutions, was possible to trace the vital status of 92% of the cohort and 100% of the causes of deaths. The results showed that employees of underground coal mining in Parana had a risk of mortality from lung cancer higher than might be expected to the male population of the state of Parana, observing an increase in risk with the time of underground service. However, this increase in mortality from lung cancer was not observed for surface workers. Among several carcinogenic agents present in the mine environment, radon gas and its decay products can be identified as the major cause for this increase in risk of lung cancer for these workers, once other epidemiological studies in coal mining, which have no risk of exposure to radon, do not present an increased of mortality risk from lung cancer

  11. Using magnetic resonance imaging to monitor CH4 hydrate formation and spontaneous conversion of CH4 hydrate to CO2 hydrate in porous media.

    Science.gov (United States)

    Baldwin, Bernard A; Stevens, Jim; Howard, James J; Graue, Arne; Kvamme, Bjorn; Aspenes, Erick; Ersland, Geir; Husebø, Jarle; Zornes, David R

    2009-06-01

    Magnetic resonance imaging was used to monitor and quantify methane hydrate formation and exchange in porous media. Conversion of methane hydrate to carbon dioxide hydrate, when exposed to liquid carbon dioxide at 8.27 MPa and approximately 4 degrees C, was experimentally demonstrated with MRI data and verified by mass balance calculations of consumed volumes of gases and liquids. No detectable dissociation of the hydrate was measured during the exchange process. PMID:19168304

  12. Gas Hydrates

    International Nuclear Information System (INIS)

    Gas hydrates are solid, similar to the ice and made up of rigid cages of water molecules, that they contain gas molecules, mainly methane, they can be formed and to remain stable to discharges pressures and relatively low temperatures, since present enough quantity of hydrocarbons is. The presence of the Gas Hydrates has been detected in high latitudes under the permafrost (Siberia and Alaska) and under the deep marine in silts of continental margins and elevations of the sea bottom (coast out California, Bearing Sea, Beaufort sea, coast out Newfoundland, Baltimore Canyon, Mexico Gulf and Colombian basin among other) its presence has also been postulated in intracratonics basins like in the Black and Caspio Sea. Gas hydrates have been known from 1810, but only in 1934 the first publication appeared (Hammer Schmidt) in connection with the gas piper line for the hydrates formation. The geologic occurrence is known from 1960 with the discovery for the Russian of Messoyakha Field (Siberia) and in 1972 for Arch-Exxon in the well Eilleen State 2 in Alaska. The quantity of gas present in the gas hydrates postulated in the world is considered that 18 x 1015 m3 could reach (6.5 x 105 American Quintillion cubic feet) the above-mentioned means that there would be more carbon in the gas hydrates than the acquaintance twice or estimated in the reservations of fossil fuels of the world and that this energy source could replace the world necessities until the X XI century. In Colombessities until the X XI century. In Colombia two areas have been postulated with gas hydrates: Colombian basin in the Caribbean Sea and the Panama Basin

  13. Gas Hydrates

    International Nuclear Information System (INIS)

    The hydrates of gas are solid, similar to the ice, made up of rigid cages of molecules of water that they contain molecules of gas, mainly methane. They can be formed and to remain stable to discharges pressures and relatively low temperatures, since present enough quantity of hydrocarbons. The quantity of present gas in the hydrates of gas postulated in the world is considered that could reach 18 x 10 15 m3 (6.5 x 10 5 TCF - American trillion cubic feet). The above mentioned means that there would be more carbon in the hydrates of gas than the acquaintance twice or estimated in the reservations of fossil fuels of the world. And that this energy source could replace the world necessities until the X XI Century. In Colombia two areas have been postulated with hydrates of Gas: the Colombian basin in the Caribbean Sea and the Panama Basin in the Pacific Ocean, with dear reservations of gas that overcome 120 and 300 TCF respectively. These quantities are very favorably compared with the conventional Colombian reservations of gas of only 11 TCF

  14. Aqualite, a new mineral species of the eudialyte group from the Inagli alkaline pluton, Sakha-Yakutia, Russia, and the problem of oxonium in hydrated eudialytes

    Science.gov (United States)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2007-12-01

    Aqualite, a new eudialyte-group mineral from hydrothermally altered peralkaline pegmatites of the Inagli alkaline pluton (Sakha-Yakutia, Russia) is described in this paper. Natrolite, microcline, eckermanite, aegirine, batisite, innelite, lorezenite, thorite, and galena are associated minerals. Aqualite occurs as isometric crystals up to 3-cm across. The color is pale pink, with a white streak and vitreous luster. The mineral is transparent. The fracture is conchoidal. The mineral is brittle; no cleavage or parting is observed. The Mohs’ hardness is 4 to 5. The density is 2.58(2) g/cm3 (measured by the volumetric method) and 2.66 g/cm3 (calculated). Aqualite is optically uniaxial (+), ? = 1.569(1) and ? = 1.571(1). The mineral is pleochroic from colorless to pale pink on X and pink on Y, ? X-ray powder pattern [ d, Å ( I)( hkl)] are: 4.39(100)(2005), 2.987(100)(315), 2.850(79)(404), 10.50(44)(003), 6.63(43)(104), 7.06(42)(110), 3.624(41)(027), and 11.43(39)(101). The chemical composition (electron microprobe, H2O determined with the Penfield method) is as follows (wt %): 2.91 Na2O, 1.93 K2O, 11.14 CaO, 1.75 SrO, 2.41 BaO, 0.56 FeO, 0.30 MnO, 0.17 La2O3, 0.54 Ce2O3, 0.36 Nd2O3, 0.34 Al2O3, 52.70 SiO2, 12.33 ZrO2, O.78 TiO2, 0.15 Nb2O5; 1.50 Cl, 9.93 H2O,-O=Cl2 0.34; where the total is 99.46. The empirical formula calculated on the basis of Si + Zr + Ti + Al + Nb = 29 apfu is as follows: [(H3O)7.94Na2.74K1.20Sr0.49Ba0.46Fe0.23Mn0.12]?13.18(Ca5.79REE0.19)?5.98 (Zr2.92Ti0.08)?3.0(Si25.57Ti0.21Al0.19Nb0.03)S26.0[O66.46(OH)5.54]?72.0 [(OH)2.77Cl1.23]?4.0. The simplified formula is (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl. Aqualite differs from typical eudialyte by the extremely low contents of Na and Fe, with more than 50% Na being replaced with the (H3O)+ group. The presence of oxonium ions is confirmed by IR spectroscopic and X-ray single-crystal diffraction analysis. The mineral is compared with five structurally studied high-oxonium analogues from alkaline plutons of other regions. All of these minerals were formed at a relatively low temperature through the ion-exchange transformation of “protoeudialytes”; the successor minerals inherited the principal structural and compositional features of the precursor minerals. The name aqualite is derived from the Latin aqua in reference to its specific chemical composition. The type material of aqualite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  15. Catalysts for Enhanced CO2-CH4 Exchange in Natural Gas Hydrates. An experimental feasibility study of exchange enhancement by use of chemical additives

    OpenAIRE

    Hossainpour, Reza

    2013-01-01

    Gas hydrate is a solid state of gas and water at high pressure and low temperature conditions. Vast energy potential is associated with gas hydrates and extensive on-going research aims at addressing the technical viability of production from hydrate deposits. Two different approaches to produce natural gas from hydrate reservoir have been proposed. Either decompose the hydrate by altering thermodynamic conditions or expose the hydrate to a thermodynamically more stable hydrate former inducin...

  16. Water retention curve for hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Santamarina, J. Carlos

    2013-11-01

    water retention curve plays a central role in numerical algorithms that model hydrate dissociation in sediments. The determination of the water retention curve for hydrate-bearing sediments faces experimental difficulties, and most studies assume constant water retention curves regardless of hydrate saturation. This study employs network model simulation to investigate the water retention curve for hydrate-bearing sediments. Results show that (1) hydrate in pores shifts the curve to higher capillary pressures and the air entry pressure increases as a power function of hydrate saturation; (2) the air entry pressure is lower in sediments with patchy rather than distributed hydrate, with higher pore size variation and pore connectivity or with lower specimen slenderness along the flow direction; and (3) smaller specimens render higher variance in computed water retention curves, especially at high water saturation Sw > 0.7. Results are relevant to other sediment pore processes such as bioclogging and mineral precipitation.

  17. Evaluation of Hydrated Lime Filler in Asphalt Mixtures

    OpenAIRE

    Mohammed Abbas Hasan Al-Jumaily

    2008-01-01

    Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fund...

  18. Thermodynamics of hydration of MX80-Na: an experimental study of the hydration energies

    OpenAIRE

    Gailhanou, He?le?ne; Blanc, Philippe; Lassin, Arnault; Vieillard, Philippe; Denoyel, R.; Bloch, E.; Gaboreau, Ste?phane; Giffaut, Eric

    2012-01-01

    Hydration properties of swelling clay minerals may be very variable depending on the chemical composition of the clay, on the nature of the interlayer cations and on the interlayer charge (Berend et al., 1995; Vieillard et al., 2011). The Wyoming smectite has been largely studied, notably for assessing its hydration behavior as a function of the interlayer cations, in connection with its structural characteristics (Ferrage et al., 2005; Salles et al., 2007). In the present work, carried out a...

  19. Fe-containing phases in hydrated cements

    International Nuclear Information System (INIS)

    In this study synchrotron X-ray absorption spectroscopy (XAS) has been applied, an element specific technique which allows Fe-containing phases to be identified in the complex mineral mixture of hydrated cements. Several Fe species contributed to the overall Fe K-edge spectra recorded on the cement samples. In the early stage of cement hydration ferrite was the dominant Fe-containing mineral. Ferrihydrite was detected during the first hours of the hydration process. After 1 day the formation of Al- and Fe-siliceous hydrogarnet was observed, while the amount of ferrihydrite decreased. The latter finding agrees with thermodynamic modeling, which predicts the formation of Fe-siliceous hydrogarnet in Portland cement systems. The presence of Al- and Fe-containing siliceous hydrogarnet was further substantiated in the residue of hydrated cement by performing a selective dissolution procedure. - Highlights: • Fe bound to ferrihydrite at early age hydration • Fe found to be stable in siliceous hydrogarnet at longer term age hydration • Fe-containing AFt and AFm phases are less stable than siliceous hydrogarnet. • The study demonstrates EXAFS used to identify amorphous or poorly crystalline phases

  20. Estudio de la influencia de los medios con presencia de sulfatos en hormigones con cementos sulforresistentes y adiciones minerales: Parte 2. Hormigones expuestos a sulfato magnésico (MgSO4) / The influence of sulfuric environments on concretes elaborated with sulfate resistant cements and mineral admixtures: Part 2: Concrete exposed to Magnesium Sulfate (MgSO4)

    Scientific Electronic Library Online (English)

    Bernal, Camacho, J; Mahmoud, Abdelkader, S; Reyes, Pozo, E; Monteagudo, Viera, S.

    2013-12-01

    Full Text Available El presente trabajo estudia la resistencia de hormigones al ataque de sulfatos provenientes de sulfato magnésico (MgSO4) y compara estos valores con resultados previos de los mismos hormigones atacados con sulfato sódico (Na2SO4). De esta manera se estudia la interacción del catión que acompaña al i [...] on sulfato durante su afectación a la matriz cementícia. Para lo anterior, se diseñaron cuatro dosificaciones empleando cementos sulforresistentes y adiciones minerales (humo de sílice, ceniza volante y escoria de alto horno). Los hormigones se sumergieron, por distintos periodos de tiempo, en disolución de sulfato magnésico (MgSO4) de concentración 1M, para después realizarles ensayos mecánicos y a nivel microestructural. Los valores obtenidos se compararon con los obtenidos en el hormigón de referencia curado en hidróxido cálcico. El hormigón con escoria de alto horno presentó el mejor comportamiento frente a MgSO4, siendo las mezclas de humo de sílice y ceniza volante las más susceptibles. La resistencia del hormigón con escoria se atribuye a las características de los silicatos hidratados formados durante la hidratación, los cuales incorporan aluminio en las cadenas impidiendo su descomposición ante un ataque por magnesio. El medio con sulfato magnésico mostro una mayor agresividad que el medio con sulfato sódico. Abstract in english The present work studies the resistant of the concrete against magnesium sulfate (MgSO4) and compare the results with values obtained previously of the same concretes exposed to sodium sulfate (Na2SO4). Thus, it is possible analyze the influence of the cation type. To that end, four different concre [...] te mixes were made with sulfur resistant cement and mineral admixtures (silica fume, fly ash and blast furnace slag). The concretes were submerged for different period in magnesium sulfate (MgSO4). After that, different tests were carried out to define mechanical and microstructural properties. The results obtained were compared with reference values of concretes cured in calcium hydroxide [Ca(OH)2]. According to the results, the concrete with blast furnace slag presented the best behavior front MgSO4, meanwhile the concretes with silica fume and fly ash were the most susceptible. The resistance of the concrete with blast furnace slag could be attributed to the characteristics of the hydrated silicates formed during the hydration time, which include aluminum in the chemical chain that hinder its chemical decomposition during the attack of magnesium. The magnesium sulfate solution was most aggressive than sodium sulfate solution.

  1. Cyclopentane Hydrate for Hydrate Wetting Studies

    OpenAIRE

    Abdulkader, Bashir Mohammed Hissen

    2013-01-01

    Abstract Gas hydrates are often found in the systems for production of petroleum, natural gas and water systems, which is highly undesirable. In some systems the hydrates can form rapidly into large plugs and agglomerate in the transportation lines and blockage the systems, especially, in the deep sea and permafrost regions. Generally, hydrates plug agglomeration has been prevented using one of three methods, including anti-agglomeration in which surfactants are ...

  2. The healthy newborn hydration model: a new model for understanding newborn hydration immediately after birth.

    Science.gov (United States)

    Mulder, Pamela J; Gardner, Sue E

    2015-01-01

    The normal small volume of breast milk produced in the first 2 days following birth may raise concerns about adequate hydration in breast-fed newborns. These concerns are further magnified when breast-fed infants lose ?7% of their birth weight within 2 days postnatally. Weight loss following birth is presumably mostly water loss that could result in hypohydration and subsequent hypernatremic dehydration. However, excess fluid loss immediately following birth is a normal and necessary process. Furthermore, newborns exposed to excess fluid intake during labor may need to lose ?7% of birth weight in the first 2 days following birth in order to achieve euhydration. Normal newborn fluid loss following birth confounds the use of weight loss as the sole measure of newborn hydration. We thus propose the healthy newborn hydration model that highlights the normalcy of newborn weight loss immediately following birth and the healthy newborn's compensatory mechanisms for preserving adequate hydration. We also recommend the use of serum sodium to measure intravascular osmolarity in addition to monitoring weight loss to obtain a more comprehensive newborn hydration assessment. Research is necessary in healthy newborns to identify relationships among fluids received in utero, newborn weight loss, and hydration, as evaluated with laboratory measures, in the first 2 days following birth. This information will guide clinicians in correctly identifying newborns with inadequate hydration who are in need of supplementary fluids versus newborns with adequate hydration for whom exclusive breast-feeding can be supported and encouraged. PMID:25504955

  3. The Saturation Level of Methane Hydrate in Natural Sediments

    Science.gov (United States)

    Kawasaki, T.; Lu, H.; Fujii, T.; Ripmeester, J. A.

    2008-12-01

    The accurate estimate of the resource of natural gas hydrate is one of the most important issues in assessing the energy potential of natural gas hydrate, which relies largely on the data precision of hydrate saturation level in the sediments of a reservoir. Occurring in sediment pore has been recognized as the primary occurrence mode of gas hydrate in the Eastern Nankai trough area. It was suggested that the distribution of coarse-grained sands is one of the most important factors controlling the occurrence of natural gas hydrates. This research aimed at elucidating the particle size and clay mineral effects on hydrate saturation in sediments through an experiment approach. The specimens, including sand, silty sand, silt, representing of the main sediment types recovered from the gas hydrate distribution region of the Eastern Nankai Trough, were tested. The obtained results from the experiments clearly indicate a particle size and clay content dependent trend, being low in saturation in fine sediment but high in coarse sediment. These results are generally consistent with NMR logging results for high-saturation samples, but somewhat different for samples with medium or low saturation levels. For a better understanding of the mechanism of these two factors, studies have been carried out to investigate the saturation level of methane hydrate in a series of silica powders and clay. The results obtained indicate that particle size and clay contents are the two key factors determining the saturation level of gas hydrate in sediments: the finer the particle size and/or the higher the clay content, the lower the hydrate saturation. It has been found that fundamentally the effect of particle size or clay mineral on hydrate saturation level can be accredited to specific surface area of sediment. This study was carried out as a part of the research undertaken by The Research Consortium for Methane Hydrate Resources in Japan (MH21)

  4. The hydratation of tertiary acetylene glycerin

    International Nuclear Information System (INIS)

    In this chapter of book author received as a result of hydratation of acetylene glycerin substituted oxi tetra hydro peronylidene-oxi tetra hydro-?-piron from (X L V) til (L I) exposed to chemical transformation in such reactions as dehydration and others

  5. Thermoluminescence characterization of isolated minerals to identify oranges exposed to ?-ray, e-beam, and X-ray for quarantine applications

    International Nuclear Information System (INIS)

    Identification of irradiated fruits is of paramount importance to address the limitation of irradiation technology because of varying national and international regulations. Thermoluminescence (TL) analysis was carried out to identify oranges irradiated with ?-ray, electron beam and X-ray. Non-irradiated samples exhibited background TL signals, but all the irradiated samples showed defined TL glow curves characterized by a prominent peak at 158-163 deg C. Characterizations of the irradiated standard minerals showed that feldspars were the major contributors to the TL emission and stable TL signals revealed a successful detection of irradiated oranges even after a prolonged storage. (author)

  6. Gas hydrates and magnetism : comparative geological settings for diagenetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Esteban, L.; Enkin, R.J. [Natural Resources Canada, Sidney, BC (Canada). Geological Survey of Canada; Hamilton, T. [Camosun College, Victoria, BC (Canada)

    2008-07-01

    Geophysical and geochemical methods assist in locating and quantifying natural gas hydrate deposits. They are also useful in understanding these resources, their climate impacts and their potential role in geohazards. In order to understand the mechanisms of gas hydrate formation and its natural distribution in sediments, magnetic studies were conducted on cores from three different geological settings. This paper presented the results of a detailed magnetic investigation, as well as petrological observations, that were conducted on cores from a permafrost setting in the Mackenzie Delta located in the Canadian Northwest Territories Mallik region, and two marine settings, from the Cascadia margin off Vancouver Island and the Indian National Gas Hydrate Program from the Bengal Fan. The paper provided background information on the permafrost setting in Mallik region of the Mackenzie Delta as well as the Cascadia margin. The magnetic properties of gas hydrate bearing sediments were found to be a combination of the original detrital content and the diagenetic transformations of iron minerals caused by the unique environment produced by gas hydrate formation. The availability of methane to provide food for bacteria coupled with the concentration of solutes outside gas hydrate accumulation zones led to the creation of iron sulphides. These new minerals were observable using magnetic techniques, which help in delineating the gas hydrate formation mechanism and may be developed into new geophysical methods of gas hydrate exploration. 7 refs., 7 figs.

  7. Spectroscopic determination of optimal hydration time of zircon surface

    International Nuclear Information System (INIS)

    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 (ZrSiO4) 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 Dy3+, Eu3+ and Er3 in the bulk of zircon. The Dy3+ is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy3+ 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 howed that the zircon surface have a 16 h optimal hydration time. (Author)

  8. Hydrate characterization research overview

    Energy Technology Data Exchange (ETDEWEB)

    Malone, R.D.

    1993-06-01

    Gas hydrate research has been focused primarily on the development of a basic understanding of hydrate formation and dissociation in the laboratory, as well as in the field. Laboratory research on gas hydrates characterized the physical system, which focused on creating methane hydrates samples, tetrahydrofuran (THF) hydrate samples, consolidated rock samples, frost base mixtures, water/ice-base mixtures, and water-base mixtures. Laboratory work produced measurements of sonic velocity and electrical resistivity of hydrates. As work progressed, areas, such as the Gulf of Mexico and the Guatemala Trench, where gas hydrates are likely to occur were identified, and specific high potential areas were targeted for detailed investigation. The testing of samples and recovered cores from such areas provided information for detection of hydrate formations in the natural environment. Natural gas hydrate samples have been tested for thermal properties, dissociation properties, fracture mechanics, and optical properties. Acoustical properties were investigated both in the laboratory and, as possible, in the field. Sonic velocity and electrical resistivity measurements will continue to be obtained. These activities have been undertaken in hydrate deposits on Alaska`s North Slope, the Gulf of Mexico and the US East coast offshore, as well as other gas hydrate target areas.

  9. Gas hydrate and humans

    Science.gov (United States)

    Kvenvolden, K.A.

    2000-01-01

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

  10. Combustion of Methane Hydrate

    Science.gov (United States)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding from the experimental component of the research was that hydrates can burn completely, and that they burn most rapidly just after ignition and then burn steadily when some of the water in the dissociated zone is allowed to drain away. Excessive surfactant in the water creates a foam layer around the hydrate that acts as an insulator. The layer prevents sufficient heat flux from reaching the hydrate surface below the foam to release additional methane and the hydrate flame extinguishes. No self-healing or ice-freezing processes were observed in any of the combustion experiments. There is some variability, but a typical hydrate flame is receiving between one and two moles of water vapor from the liquid dissociated zone of the hydrate for each mole of methane it receives from the dissociating solid region. This limits the flame temperature to approximately 1800 K. In the theoretical portion of the study, a physical model using an energy balance from methane combustion was developed to understand the energy transfer between the three phases of gas, liquid and solid during the hydrate burn. Also this study provides an understanding of the different factors impacting the hydrate's continuous burn, such as the amount of water vapor in the flame. The theoretical study revealed how the water layer thickness on the hydrate surface, and its effect on the temperature gradient through the dissociated zone, plays a significant role in the hydrate dissociation rate and methane release rate. Motivated by the above mentioned observation from the theoretical analysis, a 1-D two-phase numerical simulation based on a moving front model for hydrate dissociation from a thermal source was developed. This model was focused on the dynamic growth of the dissociated zone and its effect on the dissociation rate. The model indicated that the rate of hydrate dissociation with a thermal source is a function of the dissociated zone thickness. It shows that in order for a continuous dissociation and methane release, some of the water from the dissociated zone needs to be drained. The results

  11. Hydration of Portland cement with additions of calcium sulfoaluminates

    Energy Technology Data Exchange (ETDEWEB)

    Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2013-01-15

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

  12. Origins of hydration lubrication

    Science.gov (United States)

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

    2015-01-01

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

  13. 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.

  14. Nanomechanical properties of hydrated carious human dentin.

    Science.gov (United States)

    Marshall, G W; Habelitz, S; Gallagher, R; Balooch, M; Balooch, G; Marshall, S J

    2001-08-01

    Most restorative materials are bonded to caries-affected dentin that has altered structure. We tested the hypothesis that hydrated dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated dentin from 8 carious and non-carious human teeth. Indentations in intertubular dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of intertubular dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular dentin values were unaltered in transparent dentin, and intratubular mineral had values between those of normal peritubular and intertubular dentin. Superficial areas contained distorted tubules without peritubular dentin or intratubular mineral. PMID:11669491

  15. 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.

  16. Influence of hydrating agents on MgO hydration

    OpenAIRE

    Matabola, Kgabo P.; Merwe, Elizabet Margaretha; Strydom, Christien A.; Labuschagne, Frederick J. W.

    2010-01-01

    BACKGROUND: The influence of different hydrating agents on the pH of the hydrating solutions, rate of hydration of MgO to Mg(OH)2 and product surface area was studied as a function of temperature of hydration. Hydrating agents used were aqueous solutions of ammonium chloride, magnesium acetate, magnesium nitrate, nitric acid, acetic acid, magnesium chloride, sodium acetate and hydrochloric acid and distilled water as control. RESULTS: There was not a significant difference in the hydration be...

  17. Thermodynamic and structural characteristics of cement minerals at elevated temperature

    International Nuclear Information System (INIS)

    We have instituted an experimental and including program designed to elucidate the structural and thermodynamic response of cement minerals to elevated temperature. Components of the program involve: (a) synthesis of hydrated Ca-silicates; (b) structural analysis of cement phases induced by heating and dehydration/rehydration; (c) mechanistic and thermodynamic descriptions of the hydration/dehydration behavior of hydrated Ca-silicates as a function of temperature, pressure and relative humidity; (d) study of naturally occurring hydrated Ca-silicates; and (e) measurements of thermodynamic data for hydrated Ca-silicates

  18. Dissolution rates of pure methane hydrate and carbon-dioxide hydrate in undersaturated seawater at 1000-m depth

    Science.gov (United States)

    Rehder, G.; Kirby, S.H.; Durham, W.B.; Stern, L.A.; Peltzer, E.T.; Pinkston, J.; Brewer, P.G.

    2004-01-01

    To help constrain models involving the chemical stability and lifetime of gas clathrate hydrates exposed at the seafloor, dissolution rates of pure methane and carbon-dioxide hydrates were measured directly on the seafloor within the nominal pressure-temperature (P/T) range of the gas hydrate stability zone. Other natural boundary conditions included variable flow velocity and undersaturation of seawater with respect to the hydrate-forming species. Four cylindrical test specimens of pure, polycrystalline CH4 and CO2 hydrate were grown and fully compacted in the laboratory, then transferred by pressure vessel to the seafloor (1028 m depth), exposed to the deep ocean environment, and monitored for 27 hours using time-lapse and HDTV cameras. Video analysis showed diameter reductions at rates between 0.94 and 1.20 ??m/s and between 9.0 and 10.6 ?? 10-2 ??m/s for the CO2 and CH4 hydrates, respectively, corresponding to dissolution rates of 4.15 ?? 0.5 mmol CO2/m2s and 0.37 ?? 0.03 mmol CH4/m2s. The ratio of the dissolution rates fits a diffusive boundary layer model that incorporates relative gas solubilities appropriate to the field site, which implies that the kinetics of the dissolution of both hydrates is diffusion-controlled. The observed dissolution of several mm (CH4) or tens of mm (CO2) of hydrate from the sample surfaces per day has major implications for estimating the longevity of natural gas hydrate outcrops as well as for the possible roles of CO2 hydrates in marine carbon sequestration strategies. ?? 2003 Elsevier Ltd.

  19. In Situ Raman Spectroscopic Measurements of Undisturbed Seafloor Hydrates at Barkley Canyon

    Science.gov (United States)

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

    2006-12-01

    First time in situ Raman measurements were performed on natural ocean hydrates at 850m depth in the Barkley Canyon, off Vancouver Island, Canada. Employing the sea-going spectrometer, DORISS II, the ROV Tiburon positioned the Raman probe allowing for direct interrogation of undisturbed massive exposed hydrate. The hydrate was found to be primarily composed of methane, ethane, propane, and isobutane in the Structure II crystal framework. The hydrate composition varied heterogeneously throughout the samples. Hydrate from these naturally occurring exposed mounds varied from a relatively hard yellow stained highly fluorescent hydrate to a softer white hydrate with very little to no fluorescence. Both of these hydrates were measured. Results of both the hydrate structure and composition are in close agreement with a synthetic hydrate formed in the Monterey Bay using a gas mixture to simulate gas present in the Barkley Canyon area. Hydrate was also recovered using both pressurized and non-pressurized coring techniques and quenched in liquid nitrogen for laboratory study. X-ray diffraction, NMR and Raman spectroscopy have been used to characterize the samples recovered. Comparisons between the in situ and laboratory measurements are presented here.

  20. Estimation of potential distribution of gas hydrate in the northern South China Sea

    Science.gov (United States)

    Wang, Chunjuan; Du, Dewen; Zhu, Zhiwei; Liu, Yonggang; Yan, Shijuan; Yang, Gang

    2010-05-01

    Gas hydrate research has significant importance for securing world energy resources, and has the potential to produce considerable economic benefits. Previous studies have shown that the South China Sea is an area that harbors gas hydrates. However, there is a lack of systematic investigations and understanding on the distribution of gas hydrate throughout the region. In this paper, we applied mineral resource quantitative assessment techniques to forecast and estimate the potential distribution of gas hydrate resources in the northern South China Sea. However, current hydrate samples from the South China Sea are too few to produce models of occurrences. Thus, according to similarity and contrast principles of mineral outputs, we can use a similar hydrate-mining environment with sufficient gas hydrate data as a testing ground for modeling northern South China Sea gas hydrate conditions. We selected the Gulf of Mexico, which has extensively studied gas hydrates, to develop predictive models of gas hydrate distributions, and to test errors in the model. Then, we compared the existing northern South China Sea hydrate-mining data with the Gulf of Mexico characteristics, and collated the relevant data into the model. Subsequently, we applied the model to the northern South China Sea to obtain the potential gas hydrate distribution of the area, and to identify significant exploration targets. Finally, we evaluated the reliability of the predicted results. The south seabed area of Taiwan Bank is recommended as a priority exploration target. The Zhujiang Mouth, Southeast Hainan, and Southwest Taiwan Basins, including the South Bijia Basin, also are recommended as exploration target areas. In addition, the method in this paper can provide a useful predictive approach for gas hydrate resource assessment, which gives a scientific basis for construction and implementation of long-term planning for gas hydrate exploration and general exploitation of the seabed of China.

  1. Effects of Initial Saturation and Salinity on Methane Hydrate Growth in Sandstone

    Science.gov (United States)

    Hauge, L. O.; Birkedal, K.; Ersland, G.; Graue, A.

    2012-12-01

    The nature of gas hydrate formation in sediments has been studied with emphasis on two variables: saturation and salinity. A series of hydrate formation experiments in sandstone have been conducted to better understand mechanisms of hydrate growth and pore filling in sedimentary systems. The formation rate has been quantified based on the amount of CH4 consumed during formation at constant pressure (8.37 MPa) and temperature (4 °C). The Fill fraction, defined as the fraction of initial water converted to hydrate was used to quantify final hydrate conversion and amount of residual free water. The hydrate formation rate increased during the first period of hydrate formation for low pore water salinities (0.1-1.0 wt% NaCl) and lower initial brine saturations (Hydrate saturations, Sh, from 0.1 - 0.4 fractions of pore volume). For higher salinities (3.5 wt % NaCl) the rate of formation was continuously decreasing, resulting in slower formation due to inhibition. Various hydrate growth patterns were identified through Magnetic Resonance Imaging. Low initial saturations generally revealed uniform hydrate growth while higher saturations with higher salinities exposed both uniform and piston-like hydrate growth pattern. Higher initial water saturations resulted in higher residual water saturations after hydrate formation independent of brine salinity.

  2. High-pressure gas hydrates

    OpenAIRE

    Loveday, J. S.; Nelmes, R. J.

    2008-01-01

    It has long been known that crystalline hydrates are formed by many simple gases that do not interact strongly with water, and in most cases the gas molecules or atoms occupy 'cages' formed by a framework of water molecules. The majority of these gas hydrates adopt one of two cubic cage structures and are called clathrate hydrates. Notable exceptions are hydrogen and helium which form 'exotic' hydrates with structures based on ice structures, rather than clathrate hydrates, even at low pressu...

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

    Science.gov (United States)

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

    2012-01-01

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

  4. Clay hydration/dehydration in dry to water-saturated supercritical CO2: Implications for caprock integrity

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Schaef, Herbert T.; Thompson, Christopher J.; Turcu, Romulus VF; Miller, Quin R.; Chen, Jeffrey; Hu, Jian Z.; Hoyt, David W.; Martin, Paul F.; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2013-01-01

    Injection of supercritical CO2 (scCO2) for the geologic storage of carbon dioxide will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Wet scCO2 is highly reactive and capable of carbonating and hydrating certain minerals, whereas anhydrous scCO2 can dehydrate water-containing minerals. Because these geochemical processes affect solid volume and thus porosity and permeability, they have the potential to affect the long-term integrity of the caprock seal. In this study, we investigate the swelling and shrinkage of an expandable clay found in caprock formations, montmorillonite (Ca-STx-1), when exposed to variable water-content scCO2 at 50 °C and 90 bar using a combination of in situ probes, including X-ray diffraction (XRD), in situ magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), and in situ attenuated total reflection infrared spectroscopy (ATR-IR). We show that the extent of montmorillonite clay swelling/shrinkage is dependent not only on water hydration/dehydration, but also on CO2 intercalation reactions. Our results also suggest a competition between water and CO2 for interlayer residency where increasing concentrations of intercalated water lead to decreasing concentrations of intercalated CO2. Overall, this paper demonstrates the types of measurements required to develop fundamental knowledge that will enhance modeling efforts and reduce risks associated with subsurface storage of CO2.

  5. Evaluation of Hydrated Lime Filler in Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Mohammed Abbas Hasan Al-Jumaily

    2008-01-01

    Full Text Available Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by Marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .A typical dense graded mixture employed in construction of surface course pavement in Iraq in accordance with SCRB specifications was used .The materials used in this study included mineral aggregate materials (coarse and fine sizes were originally obtained from Najaf Sea quarries and two grades of asphalt cements produced from Daurah refinery which are D47 and D66 . The physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .The paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures.

  6. 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 is placed in a sample, then the sample is flooded with water and cooled [Priest et al., 2009]. We have performed a number of tests in which hydrate was formed and the uniformity of the hydrate formation was examined. These tests have primarily used a variety of modifications of the excess gas method to make the hydrate, although we have also used a version of the excess water technique. Early on, we found difficulties in creating uniform samples with a particular sand/ initial water saturation combination (F-110 Sand, {approx} 35% initial water saturation). In many of our tests we selected this combination intentionally to determine whether we could use a method to make the samples uniform. The following methods were examined: Excess gas, Freeze/thaw/form, Freeze/pressurize/thaw, Excess gas followed by water saturation, Excess water, Sand and kaolinite, Use of a nucleation enhancer (SnoMax), and Use of salt in the water. Below, each method, the underlying hypothesis, and our results are briefly presented, followed by a brief conclusion. Many of the hypotheses investigated are not our own, but were presented to us. Much of the data presented is from x-ray CT scanning our samples. The x-ray CT scanner provides a three-dimensional density map of our samples. From this map and the physics that is occurring in our samples, we are able to gain an understanding of the spatial nature of the processes that occur, and attribute them to the locations where they occur.

  7. Modelling porewater chemistry in hydrated Portland cement

    International Nuclear Information System (INIS)

    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

  8. Thermodynamics of hydration of MX80-Na: an experimental study of the hydration energies

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Hydration properties of swelling clay minerals may be very variable depending on the chemical composition of the clay, on the nature of the interlayer cations and on the interlayer charge. The Wyoming smectite has been largely studied, notably for assessing its hydration behavior as a function of the interlayer cations, in connection with its structural characteristics. In the present work, carried out as part of a collaborative Andra/BRGM/HydrASA research program for ThermoChimie project, we propose an original experimental study, based on adsorption and desorption isotherms performed on MX80 clay samples. The goal is to determine energetic contributions to the reactions of hydration, which have been revealed to be non-negligible with respect to the stability of the clay minerals. In particular, the present work addresses the problems of the hysteresis loop between adsorption and desorption isotherms and of the irreversibility of hydration reactions. This is directly related to the application of classical thermodynamics to the hydration reactions of clay minerals. In a first stage, an experimental study is dedicated to better understand the origin of the hysteresis loop which is systematically observed for the adsorption-desorption isotherms at 25 C. The development of the hysteresis loop has been studied by considering several kinetically related parameters: stabilization periods, temperatures (from 25 C to 60 C) aeriods, temperatures (from 25 C to 60 C) and hydration steps (Figure 1). No sensible change was observed in the hysteresis loop. Therefore, the amount of adsorbed water depends on the followed reaction pathway (adsorption or desorption). The variations in microstructures and in the distribution of hydration layers (0/1/2 water layers) as a function of relative humidity (RH) could provide a possible explanation for this phenomenon. Apparent Gibbs free energies of hydration have been calculated from both the adsorption and desorption isotherms. Figure 2 presents the Gibbs free energies of formation of adsorbed water ?Gdeg.f,H2Oads, obtained by considering the reaction H2O(l) = H2O(ads), calculated from the adsorption and the desorption isotherms. The calculation method has been optimized at very low RH in order to improve the accuracy of the results. The integration of P/P0 values has been performed on both the adsorption and desorption branches following the corresponding reaction pathway. The plots of ?Gdeg.f,H2Oads from the adsorption and desorption isotherms diverge from each other at low RH, because of the irreversibility of the hydration reaction. However, surprisingly, they are very similar for RH> 55%. This implies that, for this RH range, the Gibbs free energy of hydration is independent of the reaction pathway, and consequently, may be used for classical thermodynamic calculations. However, comparison between the data obtained from calorimetric measurements at two highly hydrated states (squares in Fig. 2; obtained from solution calorimetry for enthalpy and low temperature adiabatic calorimetry for entropy) and the aforementioned values at the corresponding RH, shows a non-negligible discrepancy, despite a rather large uncertainty associated with the calorimetric values. This discrepancy is not yet explained, but could originate partly from the contribution of energies of dilution in the calorimetric measurements. (authors)

  9. Compressibility of gas hydrates.

    Science.gov (United States)

    Manakov, Andrey Yu; Likhacheva, Anna Yu; Potemkin, Vladimir A; Ogienko, Andrey G; Kurnosov, Alexander V; Ancharov, Aleksei I

    2011-09-12

    Experimental data on the pressure dependence of unit cell parameters for the gas hydrates of ethane (cubic structure I, pressure range 0-2 GPa), xenon (cubic structure I, pressure range 0-1.5 GPa) and the double hydrate of tetrahydrofuran+xenon (cubic structure II, pressure range 0-3 GPa) are presented. Approximation of the data using the cubic Birch-Murnaghan equation, P=1.5B(0)[(V(0)/V)(7/3)-(V(0)/V)(5/3)], gave the following results: for ethane hydrate V(0)=1781 Å(3) , B(0)=11.2 GPa; for xenon hydrate V(0)=1726 Å(3) , B(0)=9.3 GPa; for the double hydrate of tetrahydrofuran+xenon V(0)=5323 Å(3) , B(0)=8.8 GPa. In the last case, the approximation was performed within the pressure range 0-1.5 GPa; it is impossible to describe the results within a broader pressure range using the cubic Birch-Murnaghan equation. At the maximum pressure of the existence of the double hydrate of tetrahydrofuran+xenon (3.1 GPa), the unit cell volume was 86% of the unit cell volume at zero pressure. Analysis of the experimental data obtained by us and data available from the literature showed that 1) the bulk modulus of gas hydrates with classical polyhedral structures, in most cases, are close to each other and 2) the bulk modulus is mainly determined by the elasticity of the hydrogen-bonded water framework. Variable filling of the cavities with guest molecules also has a substantial effect on the bulk modulus. On the basis of the obtained results, we concluded that the bulk modulus of gas hydrates with classical polyhedral structures and existing at pressures up to 1.5 GPa was equal to (9±2) GPa. In cases when data on the equations of state for the hydrates were unavailable, the indicated values may be recommended as the most probable ones. PMID:21717564

  10. Hydration of calcium sulfoaluminate cements - Experimental findings and thermodynamic modelling

    International Nuclear Information System (INIS)

    Calcium sulfoaluminate cements (CSA) are a promising low-CO2 alternative to ordinary Portland cements and are as well of interest concerning their use as binder for waste encapsulation. In this study, the hydration of two CSA cements has been investigated experimentally and by thermodynamic modelling between 1 h and 28 days at w/c ratios of 0.72 and 0.80, respectively. The main hydration product of CSA is ettringite, which precipitates together with amorphous Al(OH)3 until the calcium sulfate is consumed after around 1-2 days of hydration. Afterwards, monosulfate is formed. In the presence of belite, straetlingite occurs as an additional hydration product. The pore solution analysis reveals that straetlingite can bind a part of the potassium ions, which are released by the clinker minerals. The microstructure of both cements is quite dense even after 16 h of hydration, with not much pore space available at a sample age of 28 days. The pore solution of both cements is dominated during the first hours of hydration by potassium, sodium, calcium, aluminium and sulfate; the pH is around 10-11. When the calcium sulfate is depleted, the sulfate concentration drops by a factor of 10. This increases pH to around 12.5-12.8. Based on the experimental data, a thermodynamic hydration model for CSA cements based on cement composition, hydration kinetics of clinker phases and calculations of thermodynamic equilibria by geochemical speciation has been establishegeochemical speciation has been established. The modelled phase development with ongoing hydration agrees well with the experimental findings.

  11. Formation of natural gas hydrates in marine sediments 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

    Science.gov (United States)

    Clennell, M.B.; Hovland, M.; Booth, J.S.; Henry, P.; Winters, W.J.

    1999-01-01

    The stability of submarine gas hydrates is largely dictated by pressure and temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of deep marine sediments may also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our conceptual model presumes that gas hydrate behaves in a way analogous to ice in a freezing soil. Hydrate growth is inhibited within fine-grained sediments by a combination of reduced pore water activity in the vicinity of hydrophilic mineral surfaces, and the excess internal energy of small crystals confined in pores. The excess energy can be thought of as a "capillary pressure" in the hydrate crystal, related to the pore size distribution and the state of stress in the sediment framework. The base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature (nearer to the seabed) than would be calculated from bulk thermodynamic equilibrium. Capillary effects or a build up of salt in the system can expand the phase boundary between hydrate and free gas into a divariant field extending over a finite depth range dictated by total methane content and pore-size distribution. Hysteresis between the temperatures of crystallization and dissociation of the clathrate is also predicted. Growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, and lenses in muds; cements in sands) can largely be explained by capillary effects, but kinetics of nucleation and growth are also important. The formation of concentrated gas hydrates in a partially closed system with respect to material transport, or where gas can flush through the system, may lead to water depletion in the host sediment. This "freeze-drying" may be detectable through physical changes to the sediment (low water content and overconsolidation) and/or chemical anomalies in the pore waters and metastable presence of free gas within the normal zone of hydrate stability. Copyright 1999 by the American Geophysical Union.

  12. 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. PMID:19746709

  13. Gas Hydrates: It's A Gas!

    Science.gov (United States)

    In this activity, students will investigate the occurrence of gas hydrates on the ocean floor. They will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is gas hydrates. Students will discover that Earth's climate changes, and how the greenhouse effect works. They will also learn about the potential of hydrates as a major new energy resource and explore the conditions under which hydrates form.

  14. Uruguay minerals fuels

    International Nuclear Information System (INIS)

    In this report the bases for the development of the necessary works of prospection are exposed on mineral fuels of Uruguay. We have taken the set from: coal, lutitas bituminous, uranium, petroleum and disturbs. In all the cases we have talked about to the present state of the knowledge and to the works that we considered necessary to develop in each case

  15. Controls on gas hydrate stability in methane depleted sediments: Laboratory and field measurements

    Science.gov (United States)

    Lapham, L.; Chanton, J.; Martens, C. S.

    2009-12-01

    Gas hydrate deposits are the Earth’s largest reservoir of the powerful greenhouse gas methane and thus a key future energy resource. However, hydrate stability in sedimentary environments featuring highly variable methane concentrations needs to be understood to allow resource estimation and recovery. Hydrates are at chemical equilibrium and therefore stable where high pressures, low temperatures, and moderate salinities coexist with methane-saturated pore waters. When all of these conditions are not met, hydrates should dissociate or dissolve, releasing methane to the overlying water and possibly the atmosphere. In addition, other natural factors may control the kinetics of their degradation complicating models for hydrate stability and occurrence. Our measurements indicate that the pore-waters surrounding some shallow buried hydrates are not methane-saturated suggesting that dissolution should occur relatively rapidly. Yet, these hydrate deposits are known to persist relatively unchanged for years. We hypothesize that, once formed, hydrate deposits may be stabilized by natural factors inhibiting dissolution, including oil or microbial biofilm coatings. While most studies have focused on pressure and temperature changes where hydrates occur, relatively few have included measurements of in situ methane concentration gradients because of the difficulties inherent to making such measurements. Here we present recent measurements of methane concentration and stable carbon isotope gradients immediately adjacent to undisturbed hydrate surfaces obtained through deployments of novel seafloor instruments. Our results suggest that the hydrates studied are relatively stable when exposed to overlying and pore-waters that are undersaturated with methane. Concurrent laboratory measurements of methane concentration gradients next to artificial hydrate surfaces were utilized to test our protective coating hypothesis. After a stable dissolution rate for hydrate samples was established, oil and natural sediments with microbial communities were added to determine how these kinetic affects could control hydrate dissolution.

  16. Artificial Hydration and Nutrition

    Science.gov (United States)

    ... than by mouth. This is referred to as artificial hydration and nutrition. This is sometimes done when someone is recovering from a temporary problem, such as when fluids have been lost through vomiting, sweating, or diarrhea. It may also be done when ...

  17. Mineral resource of the month: vermiculite

    Science.gov (United States)

    Potter, M.J.

    2008-01-01

    Vermiculite, a hydrated magnesium-aluminum-iron silicate mineral, has a range of uses that take advantage of its fire resistance, good insulating properties, high liquid absorption capacity, inertness and low density. Most applications for vermiculite use an exfoliated (heat-expanded) form of the mineral. In general, coarser grades of vermiculite are used as loose fill insulation and in horticulture. Finer grades are used in wallboard and plasters and for animal feeds and fertilizers.

  18. An Experimental Determination of Natural Clathrate Hydrate Dissolution Rates in the Deep Sea

    Science.gov (United States)

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

    2006-12-01

    In August of 2006 we carried out a series of geochemical experiments on the massive Structure II hydrate mounds in Barkley Canyon using MBARI's ROV Tiburon deployed from the R/V Western Flyer. One of the primary questions regarding the fate of this hydrate exposure at 850m depth is the temporal persistence of un-sedimented surfaces exposed to steady currents of seawater undersaturated with methane. Previous work on the dissolution rate of laboratory prepared methane hydrate (Rehder et al., 2004) showed diameter reduction rates of ~3 m/year. These formations appeared largely unchanged from the earlier descriptions and photographs contained in media reports released in 2002 and later (Chapman et al., 2004; Lu et al., 2005) leading us to speculate that these hydrates are far slower to dissolve. In order to quantify their dissolution rates, samples of the outcropping hydrate, both a pure white hydrate and a much harder yellow, oil-stained hydrate, were collected using an ROV operated coring device and hydraulically expelled into an open mesh container for time-lapse photography over the course of the next 48 hours. By exposing these samples of natural hydrate to the flow of ambient seawater we hoped to observe the dissolution rate consistent with the local environmental conditions. Initial analysis of the time-lapse photographs obtained using a Nikon Cool-pix camera revealed an apparent diameter reduction rate for the yellow hydrate of approximately 0.040 ?m/s, corresponding to a volume loss rate of 1.3×10-6cm3/cm2/s. The observed dissolution rate of the white hydrate was significantly faster, consistent with the observed large-scale undercutting of the exposed layered structures. Assuming that the yellow hydrate has a density of 0.93 g/cm3 and an average hydration number near 6, this yields a guest gas loss rate of about 9.4×10-9 mol/cm2/s. This is approximately one-fourth the rate that was observed for the dissolution of synthetic Structure I methane hydrates under similar conditions in Monterey Bay. Thus the lifetime of the exposed surfaces must be short unless there is some form of active expulsion of fresh hydrates taking place. Chapman et al. (2004). Eos, Trans. Amer. Geophys. Union. 85: 361, 365. Lu et al. (2005). J. Geophys. Res. 110: B10204, doi:10.1029/2005JB003900. Rehder et al. (2004). Geochim. et Cosmochim. Acta 68: 285-292.

  19. Micromechanical Cohesion Force between Gas Hydrate Particles Measured under High Pressure and Low Temperature Conditions.

    Science.gov (United States)

    Lee, Bo Ram; Sum, Amadeu K

    2015-04-01

    To prevent hydrate plugging conditions in the transportation of oil/gas in multiphase flowlines, one of the key processes to control is the agglomeration/deposition of hydrate particles, which are determined by the cohesive/adhesive forces. Previous studies reporting measurements of the cohesive/adhesive force between hydrate particles used cyclopentane hydrate particles in a low-pressure micromechanical force apparatus. In this study, we report the cohesive forces of particles measured in a new high-pressure micromechanical force (MMF) apparatus for ice particles, mixed (methane/ethane, 74.7:25.3) hydrate particles (Structure II), and carbon dioxide hydrate particles (Structure I). The cohesive forces are measured as a function of the contact time, contact force, temperature, and pressure, and determined from pull-off measurements. For the measurements performed of the gas hydrate particles in the gas phase, the determined cohesive force is about 30-35 mN/m, about 8 times higher than the cohesive force of CyC5 hydrates in the liquid CyC5, which is about 4.3 mN/m. We show from our results that the hydrate structure (sI with CO2 hydrates and sII with CH4/C2H6 hydrates) has no influence on the cohesive force. These results are important in the deposition of a gas-dominated system, where the hydrate particles formed in the liquid phase can then stick to the hydrate deposited in the wall exposed to the gas phase. PMID:25785915

  20. Bacterial Utilization of Gas Hydrate and Inhibition of Crystallization in Chemosynthetic Communities, Northwestern Gulf of Mexico

    Science.gov (United States)

    Sassen, R.; Milkov, A. V.; Roberts, H. H.

    2001-12-01

    The spatial association of structure II gas hydrate with lush chemosynthetic communities of tubeworms and other organisms in the upper slope of the Gulf of Mexico is obvious. Several sites in the Green Canyon area are characterized by moderate flux of oil-related gas (methane through pentanes, carbon dioxide) and crude oil, derived from the subsurface petroleum system. Most venting gas bypasses hydrate-rich sediments, as shown by large gas plumes that enter the water column and create natural oil slicks. This low conversion rate is also demonstrated by molecular properties of venting gas that is only slightly depleted in hydrate-forming hydrocarbons. Sea floor experiments suggest crystal nucleation on available mineral particles is a limiting factor. Gas hydrate crystallized from venting gas shows isotopic fractionation consistent with selective bacterial oxidation of methane (heavy carbon and hydrogen) and concomitant production of carbon dioxide (light carbon). Natural gas hydrate is frequently permeable and porous with large internal surface area, offering a favorable substrate for bacterial utilization. Abundant free gas occurs in sediment of chemosynthetic communities even though crystallization of the hydrate is favored thermodynamically. Bacterial oxidation of free hydrocarbon gas and reduction of sulfate occur in sediment at the periphery of buried gas hydrate. No gas hydrate is observed to crystallize on living bacterial mats, tubeworms, or bivalves immersed in gas bubble trains. This observation suggests that the surface chemistry of living organisms in chemosynthetic communities inhibits crystallization of gas hydrate, possibly an adaptive trait to the environment.

  1. Rapid gas hydrate formation process

    Science.gov (United States)

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

    2013-01-15

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

  2. Animated molecular dynamics simulations of hydrated Cesium-smectite interlayers

    International Nuclear Information System (INIS)

    Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers) provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional analytical methods. Cs+ could be seen to jump from one attracting location near a layer charge site to the next, and water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. The extent of this sharing interaction in the interlayer was determined by the smectite charge distribution, but increased with increasing water content. Water molecules also could be seen to interact directly with the mineral surface, entering its ditrigonal cavities to approach attracting charge sites. The frequency and duration of cavity habitation increased with increasing water content and tetrahedral charge, and was inhibited the more perpendicular was the structural hydroxyl orientation relative to the mineral surface. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation outputoutput

  3. Spectral stratigraphy and clay minerals analysis in parts of Hellas Planitia, Mars

    Science.gov (United States)

    Das, I. C.; Joseph, J.; Subramanian, S. K.; Dadhwal, V. K.

    2014-11-01

    Absorption features that occur in reflectance spectra are a sensitive indicator of mineralogy and chemical composition for a wide variety of materials. The investigation of the mineralogy and chemical composition of surfaces give information about the origin and evolution of planetary bodies. On Mars, the processes of formation of different types of clay minerals result from different types of wet conditions viz. hydrothermalism, subsurface/groundwater weathering, surface alteration etc. The image analyzed in the present study was frt000947f- 164-trr3 (-27.87N-65.06E). Through the spectral stratigraphic characterization along a crater wall, eight (8) different layers were identified considering the spectral variability and their position. In Hellas Planitia, the alteration minerals identified by CRISM based on distinctive absorptions from 0.4 to3.9 ?m include Al-rich smectite, montmorillonite, phyllosilicate mineral at 2.2 ?m and 2.35 ?m, including strong absorption feature noticed at 1.9 ?m. We conclude that the layers exposed in the crater wall help characterize the compositional stratigraphy for confirming the presence of hydrated minerals in this region as an outcome of geohydrological weathering process.

  4. 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)

  5. Hydration of ions in confined spaces and ion recognition selectivity.

    Science.gov (United States)

    Okada, Tetsuo; Harada, Makoto; Ohki, Takumi

    2009-02-01

    The hydration of ions in confined spaces, such as the interior of ion-exchange resins, micelles, and surface monolayers, is discussed on the basis of results obtained with X-ray absorption fine structure studies, electrophoresis, and ion-transfer voltammetry. The general trends are that anions are partly dehydrated therein, whereas cations are likely to keep their first hydration shells. For bromide ions, the hydration numbers under various circumstances have been determined. The extents of dehydration depend not only on the structure of the cationic sites electrostatically attracting bromide ions but also on whether the cationic sites are exposed to a solution or are effectively shielded from it. These findings will be useful for designing the systems for ionic recognition and separation. PMID:19212049

  6. Occurrences of possible hydrated sulfates in the southern high latitudes of Mars

    Science.gov (United States)

    Ackiss, Sheridan E.; Wray, J. J.

    2014-11-01

    Hydrated sulfate minerals record the history of water and habitable environments on Mars, yet prior studies of them have neglected a vast region surrounding the planet's south pole. Some of the few sulfates reported there are localized to putative ancient volcanoes that may have erupted under an ice sheet, possibly forming sulfates via hydrothermal alteration. Alternatively, sulfates may have formed more recently from sunlight causing minor melting of polar ices and the weathering of embedded dust particles, a process thought to explain the sulfates found near Mars' north pole. To test these hypotheses, we searched for southern high-latitude sulfates using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO), focusing on regions that include putative volcanoes or geologically similar landforms. In 217 targeted images, we used spectral parameters to identify regions of interest from which we extracted spectra. The spectra were then visually compared to laboratory spectra to identify possible hydrated mineral constituents. In this paper, we present spectra from 16 of the images and statistics derived from the full set of 217, along with spectra from one mapping tile. We find that hydrated sulfates are found throughout the southern high latitudes suggesting a ubiquitous process for hydrated mineral formation and/or the relocation of hydrated minerals due to a long history of impacts, aeolian transport, weathering and periglacial processes.

  7. Hydration of pectic polysaccharides.

    Science.gov (United States)

    Ryden, P; MacDougall, A J; Tibbits, C W; Ring, S G

    2000-11-01

    The hydration and swelling of pectic polysaccharides was examined at different pHs and ionic strengths as a function of osmotic stress. For weakly charged pectic polysaccharides at low concentrations of a monovalent salt (20 mM), the main driving force for swelling originates from a polyelectrolyte effect due to the translational entropy of ions within the film. Swelling is reduced at higher salt concentrations and lower pHs. Polyelectrolyte collapse and minimal swelling is observed for more highly charged pectic polysaccharides. Replacement of the Na(+) counterion with Ca(2+) results in minimal swelling and the formation of network structures even for the weakly charged pectic polysaccharides. PMID:10951326

  8. Novel observations on the massive Barkley Canyon hydrates

    Science.gov (United States)

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

    2006-12-01

    We report on the early results of an August 2006 expedition to the massive exposed hydrates found at 850m depth in Barkley Canyon, off-shore Vancouver Island. We used the ROV Tiburon to explore, image, and sample the site, and also to carry out a series of novel experimental techniques and measurements in situ. We used the DORISS II laser Raman spectrometer for direct real time in situ measurement of hydrate composition and structure. The DORISS II system was equipped with highly modified pressure compensated optical fibers, resulting in far less signal loss than in earlier versions. This resulted in identification of gases including methane, ethane, propane, and isobutane in the Structure II hydrate simply by holding the probe head in the vehicle arm, pointing, and focusing the beam with a moveable internal stage. The site revealed white, easily cored, non-fluorescent hydrate underlying much harder yellow oil stained hydrate with significant fluorescence. Raman spectra were obtained of both hydrate types. A newly built small coring system was used to obtain specimens of well defined shape, which were inserted into a mesh chamber for time lapse video imaging to determine dissolution rates. Pressurized and non-pressurized cores were also obtained for cross- calibration in the on-shore laboratory using Raman, NMR, and XRD. A first attempt at an in situ CH4-CO2 hydrate conversion experiment was made by inserting buoyant cored specimens into a glass walled chamber, introducing ~ 2 liter liquid CO2, and placing the unit on a flat plate to seal the system and prevent large scale loss of dissolved CO2 to the surrounding ocean. We collaborated with MBARI's AUV mapping team, who obtained high resolution bathymetry, side scan, and sub-sea floor acoustic images of the site.

  9. 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)

  10. Nuclear quadrupole resonance: a technique to control hydration processes in the pharmaceutical industry.

    Science.gov (United States)

    Limandri, Silvina; Visñovezky, Claudia; Pérez, Silvina C; Schurrer, Clemar A; Wolfenson, Alberto E; Ferro, Maribel; Cuffini, Silvia L; de Souza, Joel Gonçalves; Aguiar, F Armani; de Gaitani, C Masetto

    2011-03-01

    Pharmaceuticals can exist in many solid forms, which can have different physical and chemical properties. These solid forms include polymorphs, solvates, amorphous, and hydrates. Particularly, hydration process can be quite common since pharmaceutical solids can be in contact with water during manufacturing process and can also be exposed to water during storage. In the present work, it is proved that NQR technique is capable of detecting different hydrated forms not only in the pure raw material but also in the final product (tablets), being in this way a useful technique for quality control. This technique was also used to study the dehydration process from pentahydrate to trihydrate. PMID:21314133

  11. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Science.gov (United States)

    Sutton, Rebecca; Sposito, Garrison

    2002-01-01

    Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers) provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

  12. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Directory of Open Access Journals (Sweden)

    Sposito Garrison

    2002-09-01

    Full Text Available Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

  13. Dynamics of water molecules in hydrated zeolites

    Science.gov (United States)

    Kamitakahara, William A.; Wada, Noboru

    2001-03-01

    Diffusive and vibrational motions of water molecules in zeolite LTA and faujasite have been studied by quasielastic and inelastic neutron scattering, using time-of-flight, backscattering, and filter-analyzer spectrometers. The quasielastic spectra show that, in comparison to bulk water, the molecular motions are much slower, so that the temperature scale for the motions is shifted approximately 80 K higher. Despite differing pore sizes, the diffusive behavior of water in LTA and faujasite is similar. At 15 K, the spectrum of librational modes for water in LTA at a high hydration level (20 percent H_2O by weight) is similar to that of bulk ice, but shifted downward in energy by about 10 meV (80 cm^ -1). It is broad, spanning a range from 50 to 120 meV. At a lower hydration level, a narrower spectrum is observed, peaked at 80 meV. Comparisons will be made to our previous neutron scattering data on water in another confined geometry system, i.e., water in a clay mineral.

  14. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on mars from phyllosilicate mineral assemblages

    Science.gov (United States)

    Ehlmann, B.L.; Mustard, J.F.; Clark, R.N.; Swayze, G.A.; Murchie, S.L.

    2011-01-01

    The enhanced spatial and spectral resolution provided by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) has led to the discovery of numerous hydrated silicate minerals on Mars, particularly in the ancient, cratered crust comprising the southern highlands. Phases recently identified using visible/near-infrared spectra include: smectite, chlorite, prehnite, high-charge phyllosilicates (illite or muscovite), the zeolite analcime, opaline silica, and serpentine. Some mineral assemblages represent the products of aqueous alteration at elevated temperatures. Geologic occurrences of these mineral assemblages are described using examples from west of the Isidis basin near the Nili Fossae and with reference to differences in implied temperature, fluid composition, and starting materials during alteration. The alteration minerals are not distributed homogeneously. Rather, certain craters host distinctive alteration assemblages: (1) prehnite-chlorite-silica, (2) analcime-silica-Fe,Mg-smectite-chlorite, (3) chlorite-illite (muscovite), and (4) serpentine, which furthermore has been found in bedrock units. These assemblages contrast with the prevalence of solely Fe,Mg-smectites in most phyllosilicate-bearing terrains on Mars, and they represent materials altered at depth then exposed by cratering. Of the minerals found to date, prehnite provides the clearest evidence for subsurface, hydrothermal/metamorphic alteration, as it forms only under highly restricted conditions (T = 200 400??C). Multiple mechanisms exist for forming the other individual minerals; however, the most likely formation mechanisms for the characteristic mineralogic assemblages observed are, for (1) and (2), low- grade metamorphism or hydrothermal (400??C has not been found.

  15. Structure Prediction of Carbon Dioxide Hydrate and Xenon Hydrate

    Science.gov (United States)

    Xu, Hongfei

    Gas hydrate technology is one of research focus in recent years, and can be applied to solve problems in energy, environment, and other areas. Previous views had been that most gas hydrates decompose into gas and water (or ice) under 1 GPa or so, thus, research on hydrate structures in past few decades were conducted under low pressure conditions. Recent studies have shown the possibility that new structures of gas hydrate may exist under higher pressure, and this thesis aims to explore the structures of hydrate in carbon dioxide-water system and xenon-water system with the application of high pressure. The evolutionary algorithm USPEX combined with first-principle calculation is applied in this study. The main research contents include the prediction of gas hydrate structures in certain conditions performed by USPEX codes, and the analysis of their physical properties. In the carbon dioxide-water system, structures are predicted under 5 GPa, by variable composition calculation. The results demonstrate that there's no thermodynamically stable structure of carbon dioxide hydrate under that condition. Properties of some typical structures (CO2?7H2O, CO2?4H 2O), which cannot stably exist in this system, are analyzed to explain the decomposition. In the xenon-water system, variable composition calculation are performed under 10 GPa, 20 GPa and 50 GPa, respectively. The results show the existence of metastable structure of xenon hydrate which can be indexed as 2Xe?8H2O under 10 GPa. The data also illustrates there's no thermodynamically stable structures under 20 GPa and 50 GPa. To further study the structure of xenon hydrate, fixed composition calculation of 2Xe?8H 2O is conducted under 5 GPa and 10GPa, and the physical properties of that structure are investigated and described in the thesis.

  16. Structural studies of gas hydrates

    International Nuclear Information System (INIS)

    An overview of recent structural work focusing on the gas hydrates of methane and carbon dioxide is given. Both the crystal structure and the microstructure are considered. We report on the pressure-dependent molecular structure of methane clathrate hydrate using laboratory-made hydrogenous and deuterated samples investigated by neutron and hard-X-ray synchrotron diffraction experiments. The isothermal compressibilities are determined for hydrogenated and deuterated CH4 hydrate, and isotopic differences between both compounds are established for the first time. The cage filling of carbon dioxide and methane hydrate is determined and compared with predictions from statistical thermodynamic theory. In the case of small cages in methane hydrate, experimental results and predictions do not agree. Field-emission scanning electron microscopy reveals the meso- to macro-porous nature of gas hydrates formed with an excess of free gas. Furthermore, in situ measurements of the formation kinetics of porous hydrates are reported in which differences between methane and carbon dioxide are established quantitatively and the transient existence of a type II carbon dioxide structure is found. (author)

  17. Mineral Identification

    Science.gov (United States)

    John Pratte

    This lesson discusses the question 'What is a mineral?' in the context of the guessing game 'Animal, Vegetable, or Mineral?'. It introduces a definition of the term, discusses the criteria used in the definition, and presents the common physical properties used in mineral identification. The lesson includes an activity in which students observe and record the physical properties of ten specimens and attempt to identify them using an online reference for practice.

  18. Ianthinite: a rare hydrous uranium oxide mineral from Akkavaram, Andhra Pradesh, India

    International Nuclear Information System (INIS)

    Ianthinite is the only known uranyl oxide hydrate mineral that contains both U6+ and U4+. For the first time, we report ianthinite from India (at Akkavaram, Andhra Pradesh), which is hosted in basement granitoids. The mineral occurs in the form of tiny grains, encrustations and coatings in intimate association with uraninite and uranophane. X-ray diffraction (XRD) data reveals that d-spacings of the investigated ianthinite are in close agreement with the corresponding values given for ianthinite standard in International Centre for Diffraction Data (ICDD) card no. 12-272. The crystallographic parameters of the studied ianthinite are: ao = 11?3 (1)Å , bo = 7?19 (3) Å and co = 30?46 (8) Å, with a unit cell volume of 2474 (27) ?3. The association of investigated ianthinite with uraninite suggests that the former has formed due to oxidation of the latter. Since a major part of the uraninite was exposed to oxidizing meteoric water, much of it has been transformed into hydrous uranium oxide (ianthinite) and very little part remained unaltered as uranium oxide (uraninite). Absence of schoepite in the investigated ianthinite suggests that after its formation it (ianthinite) was not exposed to oxygen/oxidizing meteoric water. As the oxidation was partial and short lived, some amount of primary uraninite is also preserved. (author)

  19. Ianthinite: A rare hydrous uranium oxide mineral from Akkavaram, Andhra Pradesh, India

    Science.gov (United States)

    Singh, Yamuna; Viswanathan, R.; Parashar, K. K.; Srivastava, S. K.; Ramesh Babu, P. V.; Parihar, P. S.

    2014-02-01

    Ianthinite is the only known uranyl oxide hydrate mineral that contains both U6 + and U4 + . For the first time, we report ianthinite from India (at Akkavaram, Andhra Pradesh), which is hosted in basement granitoids. The mineral occurs in the form of tiny grains, encrustations and coatings in intimate association with uraninite and uranophane. X-ray diffraction (XRD) data reveals that d-spacings of the investigated ianthinite are in close agreement with the corresponding values given for ianthinite standard in International Centre for Diffraction Data (ICDD) card no. 12-272. The crystallographic parameters of the studied ianthinite are: ao = 11.3 (1) Å, bo = 7.19 (3) Å and co = 30.46 (8) Å, with a unit cell volume of 2474 (27) Å3. The association of investigated ianthinite with uraninite suggests that the former has formed due to oxidation of the latter. Since a major part of the uraninite was exposed to oxidizing meteoric water, much of it has been transformed into hydrous uranium oxide (ianthinite) and very little part remained unaltered as uranium oxide (uraninite). Absence of schoepite in the investigated ianthinite suggests that after its formation it (ianthinite) was not exposed to oxygen/oxidizing meteoric water. As the oxidation was partial and short lived, some amount of primary uraninite is also preserved.

  20. Window contamination on Expose-R

    Science.gov (United States)

    Demets, R.; Bertrand, M.; Bolkhovitinov, A.; Bryson, K.; Colas, C.; Cottin, H.; Dettmann, J.; Ehrenfreund, P.; Elsaesser, A.; Jaramillo, E.; Lebert, M.; van Papendrecht, G.; Pereira, C.; Rohr, T.; Saiagh, K.

    2015-01-01

    Expose is a multi-user instrument for astrobiological and astrochemical experiments in space. Installed at the outer surface of the International Space Station, it enables investigators to study the impact of the open space environment on biological and biochemical test samples. Two Expose missions have been completed so far, designated as Expose-E (Rabbow et al. 2012) and Expose-R (Rabbow et al. this issue). One of the space-unique environmental factors offered by Expose is full-spectrum, ultraviolet (UV)-rich electromagnetic radiation from the Sun. This paper describes and analyses how on Expose-R, access of the test samples to Solar radiation degraded during space exposure in an unpredicted way. Several windows in front of the Sun-exposed test samples acquired a brown shade, resulting in a reduced transparency in visible light, UV and vacuum UV (VUV). Post-flight investigations revealed the discolouration to be caused by a homogenous film of cross-linked organic polymers at the inside of the windows. The chemical signature varied per sample carrier. No such films were found on windows from sealed, pressurized compartments, or on windows that had been kept out of the Sun. This suggests that volatile compounds originating from the interior of the Expose facility were cross-linked and photo-fixed by Solar irradiation at the rear side of the windows. The origin of the volatiles was not fully identified; most probably there was a variety of sources involved including the biological test samples, adhesives, plastics and printed circuit boards. The outer surface of the windows (pointing into space) was chemically impacted as well, with a probable effect on the transparency in VUV. The reported analysis of the window contamination on Expose-R is expected to help the interpretation of the scientific results and offers possibilities to mitigate this problem on future missions - in particular Expose-R2, the direct successor of Expose-R.

  1. Chemically Accelerated Carbon Mineralization: Chemical and Biological Catalytic Enhancement of Weathering of Silicate Minerals as Novel Carbon Capture and Storage

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-07-01

    IMPACCT Project: Columbia University is developing a process to pull CO2 out of the exhaust gas of coal-fired power plants and turn it into a solid that can be easily and safely transported, stored above ground, or integrated into value-added products (e.g. paper filler, plastic filler, construction materials, etc.). In nature, the reaction of CO2 with various minerals over long periods of time will yield a solid carbonate—this process is known as carbon mineralization. The use of carbon mineralization as a CO2 capture and storage method is limited by the speeds at which these minerals can be dissolved and CO2 can be hydrated. To facilitate this, Columbia University is using a unique process and a combination of chemical catalysts which increase the mineral dissolution rate, and the enzymatic catalyst carbonic anhydrase which speeds up the hydration of CO2.

  2. Gas Hydrates: It's a Gas

    Science.gov (United States)

    In this activity, students will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is in the form of gas hydrates where methane and other hydrocarbon gases are trapped in a lattice of water molecules in deep sea sediments. Students will learn how climate change is related to the greenhouse effect. They will also learn about the potential of hydrates as a major new energy resource, and explore the conditions under which hydrates form. In addition, students will understand the use of acoustics for mapping the sea floor and sub-sea floor.

  3. Hydration of alite containing alumimium

    OpenAIRE

    Begarin, Farid; Garrault, Sandrine; Nonat, Andre?; Nicoleau, Luc

    2009-01-01

    The most important phase in cement is tricalcium silicate which leads during its hydration to the nucleation and growth of calcium silicate hydrate (referred to C-S-H (CaO)x-SiO2-(H2O)y). The development of this hydrate around the cement grains is responsible for the setting and hardening of cement pastes The general term for designating the tricalcium silicate in cements is alite. This name relates to all polymorphs containing various foreign ions inserted in their structure. These ions may ...

  4. Effect of organic matters on CO2 hydrate phase equilibrium conditions in Na-montmorillonite clay

    Science.gov (United States)

    Park, T.; Kyung, D.; Lee, W.

    2013-12-01

    Formation of gas hydrates provides an attractive idea for storing greenhouse gases in a long-term stable geological formation. Since the phase equilibrium conditions of gas hydrates indicate the stability of hydrates, estimation of the phase equilibrium conditions of gas hydrates in marine geological conditions is necessary. In this study, we have identified the effects of organic matters (glycine, glucose, and urea) and solid surface (montmorillonite (MMT)) on the three-phase (liquid-hydrate-vapor) equilibrium conditions of CO2 hydrate. CO2 phase equilibrium experiments were conducted using 0.5mol% organic matter solutions with and without 10g soil mineral were experimentally conducted. Addition of organic matters shifted the phase equilibrium conditions of CO2 hydrate to the higher pressure or lower pressure region because of higher competition of water molecules due to the dissolved organic matters. Presence of MMT also leaded to the higher equilibrium pressure due to the interaction of cations with water molecules. By addition of organic matters to the clay suspension, the hydrate phase equilibrium conditions were less inhibited compared to those of MMT and organic matters independently. The diminished magnitudes by addition of organic matters to the clay suspension (MMT > MMT+urea > MMT+glycine > MMT+glucose > DIW) were different to the order of inhibition degree without MMT (Glucose > glycine > urea > DIW). X-ray diffraction (XRD), scanning electron microscope (SEM), and ion chromatography (IC) analysis were conducted to support the hypothesis that the organic matters interact with cations in MMT interlayer space, and leads to the less inhibition of phase equilibrium conditions. The present study provides basic information for the formation and dissociation of CO2 hydrates in the geological formation when sequestering CO2 as a form of CO2 hydrate.

  5. Molecular simulation study of hydrated Na-rectorite.

    Science.gov (United States)

    Zhou, Jinhong; Boek, Edo S; Zhu, Jianxi; Lu, Xiancai; Sprik, Michiel; He, Hongping

    2015-02-17

    The swelling behavior of clay minerals is an important issue in industrial processes and environmental applications. Mixed-layer clay minerals containing a smectite fraction, such as rectorite, are neglected even though they could swell and exist in nature widely. The hydration of rectorite has not been well comprehended even though they are meaningful to mineralogy and industry. This study combines molecular dynamics (MD) and Monte Carlo (MC) simulations to disclose the swelling behavior of rectorite and compare with montmorillonite. From grand canonical Monte Carlo (GCMC) and MD simulations, we obtain swelling curves and swelling free-energy curves of rectorite with a relative humidity of 100%. With the comparisons of swelling free-energy minima, we find that the bilayer hydrate of Na-rectorite is more thermodynamically stable than the monolayer hydrate, which is similar to Na-montmorillonite. However, the interlayer sodium ions in rectorite show an asymmetrical distribution quite different from the symmetrical distribution in montmorillonite. Because of unequal layer charges between the smectite part and illite part of retorite, sodium ions prefer to distribute close to the illite part surface. PMID:25625308

  6. Observations of Hydrated Minerals on Asteroids: Pushing Back the Frontiers

    Science.gov (United States)

    2005-01-01

    The three accomplishments during this grant include: 1) Travel to 2004 Division of Planetary Science (of American Astronomical Society) Conference in Louisville, KY and presentation of Rotationally resolved spectroscopy of Vesta in the 1-4 micron region, abstract 28.07. 2) Remote observations using the IRTF on 20-21 June 2004 and 28-3 1 August 2004, and reduction of data as described in the grant proposal and descoping document. These observations confirm the presence of two different band shapes among C-class asteroid spectra in the 3-micron region. This allowed a revision of the known distribution of Ceres- and Pallas-type objects. 3) Remote observations using the IRTF on 7-10 August 2004. These observations of Vesta were presented, and the manuscript will be submitted to Icarus in June.

  7. A review of arctic gas hydrates as a source of methane in global change

    International Nuclear Information System (INIS)

    Atmospheric concentrations of methane are currently increasing at rates of about one percent per year, leading to a concern that methane, a greenhouse gas, will become an increasingly significant factor in global warming. One potential source of enormous volumes of methane is natural gas hydrates. Gas hydrates are stable only within certain ranges of temperature and pressure; outside these ranges, the cages break down and the gas molecules escape. The Arctic is particularly well endowed with gas hydrates because conditions for their occurrence are met in three distinct regions: (1) offshore in sediments of the outer continental margin, at water depths between about 400 and 2,800 m, where the base of the zone of gas hydrate stability ranges from about 300 to 700 m below the sea floor; (2) onshore in areas of continuous permafrost, where the zone of gas hydrate stability ranges in subsurface depth from about 200 to 1,200 m; and (3) on the nearshore continental shelf, where relict permafrost has persisted since times of lower sea level when the present shelf was exposed to cold subaerial temperatures. Because gas hydrates occur close to the earth's surface in these three regions, they are affected by surficial changes in pressure and temperature, and thus destabilized gas hydrates may be sources of atmospheric methane. Under the present climatic regime, the gas hydrates of the nearshore continental shelf may be the most vulnerable to change. The time needed for thermal ce to change. The time needed for thermal change to destabilize gas hydrates in this region is measured in thousands or tens of thousands of years. Because the latest major Arctic marine transgression may have been in progress for about 27,000 years, some gas hydrates associated with nearshore permafrost probably have already become unstable, releasing methane to the atmosphere

  8. Obsidian hydration profiles and dating

    Science.gov (United States)

    Zhang, Y.; Xu, X.

    2003-12-01

    Obsidian hydration dating (or more generally, glass hydration dating) has been investigated as a method to determine the age of archeological samples (e.g., Lee et al., 1974; Freidman and Long, 1976; Anovitz et al., 1999; Liritzis and Diakostamatiou, 2002; Riciputi et al., 2002). This presentation attempts to lay the theoretical foundation for understanding glass hydration. Treating hydration as diffusion into a semi-infinite medium, a theoretical foundation requires an understanding of the following: (1) water concentration at the surface (water solubility in glass and whether equilibrium is reached); (2) water diffusion in glass; (3) diffusion behavior for periodically changing temperature and periodic boundary condition; (4) possible dissolution of obsidian in water, and (5) the effect of long-term trends in temperature (global warming) and humidity (such as drying or uplift of the region, etc.). Previous experimental data and models are extrapolated to room temperature on water speciation, solubility and diffusivity. Such information is compared with that extracted from measured obsidian hydration profiles. The effect of periodic T and surface conditions on diffusion is analytically examined. We conclude: (i) molecular H2O is the dominant species at room T; (ii) the surface water concentration in obsidian hydration is roughly consistent with extrapolated water solubility at room T and a humidity of 1; (iii) high-T water diffusion data cannot be extrapolated to room T (Leschik et al., 2003); and (iv) the most reliable part of a hydration profile is at depth greater than 0.6 micrometers. Because the total hydration depth is proportional to the square root of the integration of diffusivity with respect to time, it is sensitive to not only age (for dating), but also to the variation of diffusivity, which depends on mean annual T and humidity. Only when the annual mean diffusivity is constant, and when there was no dissolution of obsidian, would it be reliable to determine the age. On the other hand, the sensitivity of the diffusivity and hence the hydration depth to climate conditions (especially humidity) means that obsidian hydration profiles may be a good climate indicator if age of obsidian can be independently determined by, e.g., C-14 dating (Riciputi et al., 2002).

  9. Energy resource potential of natural gas hydrates

    Science.gov (United States)

    Collett, T.S.

    2002-01-01

    The discovery of large gas hydrate accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans has heightened interest in gas hydrates as a possible energy resource. However, significant to potentially insurmountable technical issues must be resolved before gas hydrates can be considered a viable option for affordable supplies of natural gas. The combined information from Arctic gas hydrate studies shows that, in permafrost regions, gas hydrates may exist at subsurface depths ranging from about 130 to 2000 m. The presence of gas hydrates in offshore continental margins has been inferred mainly from anomalous seismic reflectors, known as bottom-simulating reflectors, that have been mapped at depths below the sea floor ranging from about 100 to 1100 m. Current estimates of the amount of gas in the world's marine and permafrost gas hydrate accumulations are in rough accord at about 20,000 trillion m3. Disagreements over fundamental issues such as the volume of gas stored within delineated gas hydrate accumulations and the concentration of gas hydrates within hydrate-bearing strata have demonstrated that we know little about gas hydrates. Recently, however, several countries, including Japan, India, and the United States, have launched ambitious national projects to further examine the resource potential of gas hydrates. These projects may help answer key questions dealing with the properties of gas hydrate reservoirs, the design of production systems, and, most important, the costs and economics of gas hydrate production.

  10. Evolution of iron speciation during hydration of C4AF

    International Nuclear Information System (INIS)

    It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C4AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C4AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C4AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C4AF forms C3AH6 (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C3AH6; iron does not seem to be incorpo>6; iron does not seem to be incorporated in the AFm structure

  11. 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 hydrate with a complex guest gas composition immersed in liquid CO2 there are multiple pathways for the reaction to proceed. If the hydrate cage occupancy is 100% then we suspect on thermodynamic grounds that the reaction may proceed slowly; nevertheless if cage occupancy is ROV based experiments.

  12. Adsorption of polyelectrolytes and its influence on the rheology, zeta potential, and microstructure of various cement and hydrate phases.

    Science.gov (United States)

    Zingg, Anatol; Winnefeld, Frank; Holzer, Lorenz; Pakusch, Joachim; Becker, Stefan; Gauckler, Ludwig

    2008-07-15

    In this study the influence of polycarboxylate-based polyelectrolytes on the particle interaction among tricalcium silicate (C(3)S, main clinker phase), calcium silicate hydrates (CSH), and calcium aluminate sulfate hydrates (ettringite) (main hydration phases) has been examined. These phases are the constituents of major concern during early hydration of cement suspensions. The results of zeta potential measurements on single mineral phase experiments show that the phases C(3)S and CSH are positively charged in synthetic pore solution (liquid phase of hydrating cement suspension), whereas the ettringite is negatively charged. Due to these opposite charges, ettringite crystals should coagulate with CSH phases and/or deposit on surfaces of the much larger C(3)S clinker particles. This behavior was proven by cryo-microscopic analysis of high-pressure frozen cement suspensions, which illustrates the consequences of colloidal mechanisms on the microstructure of early cement suspensions. Furthermore, it is shown that the polyelectrolytes have a much higher adsorption affinity to ettringite surfaces (hydrate phase) compared to silicate surfaces. However, the results from rheology experiments reveal that the presence of polyelectrolytes has a strong impact on the suspension properties of all investigated mineral phases by decreasing yield stress and plastic viscosity. From the results it can be concluded that the ettringite is the dominant mineral phase in terms of the state of dispersion which includes particle-particle and particle-polyelectrolyte interaction in the bulk cement system. PMID:18502439

  13. Mechanical, Thermal and Electromagnetic Properties of Hydrate-Bearing Clay, Silt, and Sand at Various Confining Pressures

    Science.gov (United States)

    Santamarina, J.; Yun, T.; Lee, J.; Martin, A.; Francisca, F.; Ruppel, C.

    2005-12-01

    With sponsorship from the ChevronTexaco JIP, we have since 2002 conducted exhaustive laboratory experiments that provide critical results to inform interpretation of field- and lab-based analyses of natural methane hydrates. Specifically, we have measured the mechanical, thermal and electromagnetic properties of sediments containing different amounts of tetrahydrofuran (THF) hydrate and subjected to different effective confining stress. The use of THF allows us to control the concentration of hydrate in pore space; this is an important advantage for evaluating the impact of hydrate concentrations on the properties of hydrate bearing sediments. For these experiments, we formed gas hydrate in kaolin clay (specific surface S_a=36 m2 g-1), precipitated and crushed silt (S_a=6 and 0.11 m2 g-1, respectively), and sand (S_a=0.019 m2 g-1) to test the impact of specific surface, porosity, and grain size on the measured physical properties. The mechanical measurements show that, while the small strain shear stiffness of uncemented sediments is controlled by the effective stress, the stiffness becomes strongly dependent on hydrate concentration once hydrate formation promotes increased interparticle coordination. At intermediate and large strain, the normally consolidated sediments display strain-hardening behavior in the absence of hydrate. When hydrate is present, the quasi-elastic behavior extends to higher axial strains, and the stress-strain response becomes less sensitive to confining pressure. The failure mode is also affected by the presence of hydrates: Specimens with 50% or 100% hydrate-filled porosity develop vertical fractures when tested at low confinement (0.03 MPa), and an approximate tenfold increase in confining pressure is required for the development of shear planes. Thermal conductivity results reflect a complex interplay of particle size, effective stress, hydrate concentration, and hydrate formation effects that have not have been fully recognized in previous studies of thermal conductivity in hydrate-bearing sediments. Our results clearly indicate that, with or without hydrate, the thermal conductivity of sediments is controlled by interparticle contact conduction so that thermal conductivity increases with increasing effective stress not only due to higher mineral volume fraction, but also due to increased interparticle coordination and contact force. The increase or even decrease in thermal conductivity with hydrate formation depends on sediment type, effective stress, and hydrate volume fraction. In particular, there may be a loss in conduction once hydrate has formed, and this phenomenon is more likely in coarse-grained sediments or sediments subjected to low effective stress due to mineral-mineral contact loss that results from volume expansion during hydrate formation. The real permittivity measured at high radio-frequencies reflects the orientational polarization of free water. On the other hand, the imaginary part of effective electrical conductivity is determined by the volume fraction of electrolyte and its electrical conductivity. Therefore, both measurements closely track the decrease in volumetric free water content during consolidation and subsequent hydrate formation.

  14. Mineral Chart

    Science.gov (United States)

    ... calcium. You'll also find this mineral in broccoli and dark green, leafy vegetables. Soy foods and ... blood and body tissues. Potassium is found in broccoli, potatoes (with skins), green leafy vegetables, citrus fruits, ...

  15. Physical property changes in hydrate-bearingsediment due to depressurization and subsequent repressurization

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, Timothy; Waite, W.F.; Kneafsey, T.J.; Winters, W.J.; Mason, D.H.

    2008-06-01

    Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed at least briefly to non-in situ conditions during recovery. To examine effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes and speeds are compared between the original and depressurized/repressurized samples. X-ray computed tomography (CT) images track how the gas-hydrate distribution changes in the hydrate-cemented sands due to the depressurization/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

  16. EXPOSE-R cosmic radiation time profile

    Science.gov (United States)

    Dachev, Tsvetan; Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin

    2015-01-01

    The aim of the paper is to present the time profile of cosmic radiation exposure obtained by the radiation risks radiometer-dosimeter (R3DR) during the ESA exposition facility for EXPOSE-R mission (EXPOSE-R) in the EXPOSE-R facility outside the Russian Zvezda module of the International Space Station (ISS). Another aim is to make the obtained results available to other EXPOSE-R teams for use in their data analysis. R3DR is a low mass and small dimensions automated device, which measures solar radiation in four channels and in addition cosmic ionizing radiation. The main results of cosmic ionizing radiation measurements are: three different radiation sources were detected and quantified: galactic cosmic rays (GCR), energetic protons from the inner radiation belt (IRB) in the region of the South Atlantic anomaly and energetic electrons from the outer radiation belt (ORB). The highest daily averaged absorbed dose rate of 506 ?Gy day-1 came from IRB protons; GCR delivered much smaller daily absorbed dose rates of 81.4 ?Gy day-1 on average, and ORB source delivered on average a dose rate of 89 ?Gy day-1. The IRB and ORB daily averaged absorbed dose rates were higher than those observed during the ESA exposition facility for EXPOSE-E mission (EXPOSE-E), whereas the GCR rate was smaller than that measured during the EXPOSE-E mission. The reason for this difference is much less surrounding constructions shielding of the R3DR instrument in comparison with the R3DE instrument.

  17. Clay Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Karl T.; Sanders, Rebecca L.; Washton, Nancy M.

    2014-03-14

    Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studies of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with speci?c sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.

  18. Methane hydrates and global climate

    Science.gov (United States)

    Kvenvolden, Keith A.

    1988-09-01

    Methane hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. The amount of methane sequestered in gas hydrates is probably enormous, but estimates of the amounts are speculative and range over three orders of magnitude (about 103 to 106 GT (gigatons = 1015 g)). A question of current interest concerns the possible consequences of an addition of methane to the atmosphere from destabilized methane hydrates due to global warming. Models of greenhouse warming predict that climatic change will be greatest in the Arctic. Thus, if methane from destabilized gas hydrates contributes to greenhouse warming, this destabilization will most likely take place first in the Arctic, particularly in the shallow nearshore regions of the Arctic Ocean where offshore permafrost is found. The process of permafrost warming and release of methane from gas hydrates may already be in progress, but the amount being released now and to be released in the 21st century is probably small. The positive feedback of this atmospheric methane on global climates will likely be minimal.

  19. New Results on Hydration in M-Type Asteroids

    Science.gov (United States)

    Landsman, Zoe A.; Campins, Humberto; Pinilla-Alonso, Noemí; Emery, Joshua P.; Lorenzi, Vania

    2014-11-01

    The M-type asteroids are a taxonomic group considered to be a candidate source of iron meteorites due to spectral and albedo similarities; however, because the spectra of M-type asteroids lack strong diagnostic absorption features in the near-infrared (NIR), their composition is difficult to constrain. High-resolution NIR spectroscopy and radar studies have shown that a metallic interpretation is unlikely to be valid for the majority of M-types. Many show weak absorption features attributed to mafic silicates (Hardersen et al. 2005, 2011; Ockert-Bell et al. 2010; Fornasier et al. 2010). Radar results show evidence for elevated metal content on the surfaces of most M-type asteroids, but few are likely to be entirely metal (Shepard et al. 2010). Surprisingly, spectrophotometric studies in the 3-?m region have indicated that hydrated minerals are relatively common among the M-type population, confounding interpretations of M-types as highly thermally processed (Rivkin et al. 1995, 2000). The shape of the 3-?m band, diagnostic of hydrated and hydroxylated minerals, is relevant to an asteroid’s thermal history (Rivkin et al. 2002, Takir & Emery 2012). To characterize this region, we have conducted a 2 - 4 ?m spectroscopic study of six M-type asteroids using SpeX at NASA’s Infrared Telescope Facility. In its LXD mode, SpeX allows us to investigate the 3-?m band at spectral resolutions unavailable during previously published studies. We report the presence of a 3-?m feature on all six asteroids, indicating hydrated minerals on the asteroids’ surfaces. We have also detected rotational variability of the 3-?m feature in asteroid (216) Kleopatra, which, interestingly, had been interpreted as “dry” in previous work (Rivkin et al. 2000). On all of our target asteroids, the 3-?m band depths are asteroid composition.

  20. 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 hydration status has a large influence on the affinity of smectites for atrazine and that air-drying treatments have the potential to modify the sorption affinity of smectitic soils for organic molecules such as atrazine. PMID:15926565

  1. Study of radio-restoration by various mineral salts and silice wich products (Tuf and Pouzzolane) of rice embryos (oryza-sativa L, Cigalon variety) exposed to cobalt 60 gamma rays

    International Nuclear Information System (INIS)

    Mutagenic treatments produce a large number of mutants per unit time and are used for plant improvement. However these treatments cause damage to cells. To counteract this radio-induced damage 2 methods are being tried: - Protection, which consists in the supply of an active product before application of mutagenic agents; - Restoration, which tries to repair the damage after mutagenic treatment. This work is devoted to restoration processes. Technique for the isolation and culture on a suitable nutrient of rice embryos (oryza sativa L, Cigalon variety) separated from non-irradiated caryopses were developed first. By separating out the embryo in this way it is possible to study in vitro the interactions between the embryo and the rest of the caryopsis (albumin + pericarp). The effects of radiations on embryos from caryopses exposed to cobalt 60 gamma rays were measured next, then the action of certain inorganic elements contained in the caryopsis tissues was analysed. On the basis of the first results obtained the differences in response between plantlets from embryos irradiated or otherwise treated or not either by zinc sulphate or by very silice-rich volcanic products (Tuf and Pouzzolane), were examined by chemical analysis techniques. These tests have allowed the detection of ionic changes induced by irradiation during the different stages of plant development and led to a better estimate of the radio-restoration mechanisms brought about by the various chemical compounds used

  2. Mutagenesis of Bacteria by Fibrous or Clay Minerals

    OpenAIRE

    Naoto Yoshida; Tadahumi Naka; Kazuyoshi Ohta

    2004-01-01

    In the present cells of Escherichia coli, Agrobacterium radiobacter, or Thiobacillus intermedius were exposed to chrysotile asbestos, kaolinite, or bentonite by culture in medium containing these minerals. Chromosomal DNA was extracted from exposed cells, then amplified by the RAPD method and band patterns were compared. DNA of bacterial cells exposed to these minerals, was amplified, in whereas that in control cells was not, or that amplified in control cells disappeared. Not only asbestos, ...

  3. Evaluation of hydration indexes in kale leaves

    OpenAIRE

    Calbo, Adonai G.; Ferreira, Marcos D.

    2011-01-01

    Hydration indexes are practical variables for quantifying plant water stress and can be useful for agronomic purposes. Three adapted hydration indexes based on relative water content, volumetric hydration, and leaf turgor pressure were evaluated in kale (Brassica oleracea var. acephala) leaf segments. Relative water content and volumetric hydration were measured in leaf segments after a water infiltration procedure with the aim of filling its large intercellular volumes (@18%v/v). The infiltr...

  4. Observation of Sintering of Clathrate Hydrates

    OpenAIRE

    Kazutoshi Gohara; Masafumi Nagayama; Toshiki Shiga; Tsutomu Uchida

    2010-01-01

    Clathrate hydrates have recently received attention as novel storage and transportation materials for natural gases or hydrogen. These hydrates are treated as powders or particles, and moderate storage temperatures (around 253 K) are set for economic reasons. Thus, it is necessary to consider the sintering of hydrate particles for their easy handling because the hydrates have a framework similar to that of ice, even though their sintering would require guest molecules in addition to water mol...

  5. Characterization of methane hydrate host sediments using synchrotron-computed microtomography (CMT)

    Science.gov (United States)

    Jones, K.W.; Feng, H.; Tomov, S.; Winters, W.J.; Prodanovic, M.; Mahajan, D.

    2007-01-01

    The hydrate-sediment interaction is an important aspect of gas hydrate studies that needs further examination. We describe here the applicability of the computed microtomography (CMT) technique that utilizes an intense X-ray synchrotron source to characterize sediment samples, two at various depths from the Blake Ridge area (a well-known hydrate-prone region) and one from Georges Bank, that once contained methane trapped as hydrates. Detailed results of the tomographic analysis performed on the deepest sample (667??m) from Blake Ridge are presented as 2-D and 3-D images which show several mineral constituents, the internal grain/pore microstructure, and, following segmentation into pore and grain space, a visualization of the connecting pathways through the pore-space of the sediment. Various parameters obtained from the analysis of the CMT data are presented for all three sediment samples. The micro-scale porosity values showed decreasing trend with increasing depth for all three samples that is consistent with the previously reported bulk porosity data. The 3-D morphology, pore-space pathways, porosity, and permeability values are also reported for all three samples. The application of CMT is now being expanded to the laboratory-formed samples of hydrate in sediments as well as field samples of methane hydrate bearing sediments.

  6. Buildings exposed to fire

    International Nuclear Information System (INIS)

    The 24 lectures presented to the colloquium cover the following subject fields: (1) Behaviour of structural components exposed to fire; (2) Behaviour of building materials exposed to fire; (3) Thermal processes; (4) Safety related, theoretical studies. (PW)

  7. Degrading permafrost and gas hydrate under the Beaufort Shelf and marine gas hydrate on the adjacent continental slope

    Science.gov (United States)

    Paull, C. K.; Dallimore, S. R.; Hughes Clarke, J. E.; Blasco, S.; Melling, H.; Lundsten, E.; Vagle, S.; Collett, T. S.

    2011-12-01

    The sub-seafloor under the Arctic Shelf is arguably the part of the Earth that is undergoing the most dramatic warming. In the southern Beaufort Sea, the shelf area was terrestrially exposed during much of the Quaternary period when sea level was ~120m lower than present. As a consequence, many areas are underlain by >600m of ice-bonded permafrost that conditions the geothermal regime such that the base of the methane hydrate stability can be >1000m deep. Marine transgression has imposed a change in mean annual surface temperature from -15°C or lower during periods of terrestrial exposure, to mean annual sea bottom temperatures near 0°C. The thermal disturbance caused by transgression is still influencing the upper km of subsurface sediments. Decomposition of gas hydrate is inferred to be occurring at the base and the top of the gas hydrate stability zone. As gas hydrate and permafrost intervals degrade, a range of processes occur that are somewhat unique to this setting. Decomposition of gas hydrate at depth can cause sediment weakening, generate excess pore water pressure, and form free gas. Similarly, thawing permafrost can cause thaw consolidation, liberate trapped gas bubbles in ice bonded permafrost. Understanding the connection between deep subsurface processes generated by transgression, surficial sediment processes near the seafloor, and gas flux into the ocean and atmosphere is important to assessing geohazard and environmental conditions in this setting. In contrast, conditions for marine gas hydrate formation occur on the adjacent continental slope below ~270m water depths. In this paper, we present field observations of gas venting from three geologically distinct environments in the Canadian Beaufort Sea, two on the shelf and one on the slope. A complimentary paper by Dallimore et al reviews the geothermal changes conditioning this environment. Vigorous methane venting is occurring over Pingo-Like-Features (PLF) on the mid-shelf. Diffuse venting of methane is occurring over a large area along the shelf edge. The methane gas emanating from both shelf features have stable isotopic compositions that indicate they are microbial in origin and are radiocarbon dead and thus sourced from geologic deposits. The PLF vents are believed to be sourced from the top of the gas hydrate stability field, while the gas emanating along the shelf edge can be from either permafrost or gas hydrate decomposition. Gas venting from both these shelf edge environments is consistent with heating associated with the last transgression. On the continental slope 3 circular topographic features up to 1 km in diameter occur in 290-790 m water depth. Data will be presented that show these are coincident with gas chimneys connected to geologic structures at depth. Water column flares, vigorous methane release and pore water freshening in cores suggest these are active vent sites and contain near seafloor marine gas hydrate. In this one area where both permafrost and marine gas hydrate occur in close proximity there is a remarkable coalescence of geologic features that are potentially related to climatically induced gas hydrate or permafrost decomposition.

  8. Structure of the hydrated electron

    International Nuclear Information System (INIS)

    An intuitive 4-water structure of the hydrated electron based on recent threshold photoionization studies is analyzed in light of past kinetic, thermodymamic, and spectroscopic measurements. It is concluded that the equilibrium state of the hydrated electron may actually be the complex (OH-...H3O)(aq). The central feature is an H2O- anion with a large distortion of one OH bond caused by the presence of the localized excess electron. A structure for the hydrated dielectron is also suggested. In these structures, thermodynamic stability is gained through hydration of the hydroxyl ion, while spectroscopic properties mainly arise from the oxonium radical. In order to examine these structures more extensively, quantum theoretical computations using Gaussian 82 have been carried out on (H2O)/sub N/- with N = 1 and 4. The computations do suggest a propensity to form a single stretched OH bond when a localized excess electron is present. This feature is similar to conclusions reached by Bettendorff, Buenker, and Peyerimhoff from extensive CI calculations on the isoelectronic monomeric species HF-, where two structures participate in an in-out dual stability: (1) a delocalized electron with a localized hydrogen atom (normal H-F bond), or (2) a localized electron with a delocalized hydrogen atom (distended H-F bond). In solution, solvent interactions are expected to lower the energy of the localized eled to lower the energy of the localized electron structure compared with the delocalized one

  9. Hydration of bilayered graphene oxide.

    Science.gov (United States)

    Rezania, B; Severin, Nikolai; Talyzin, Alexandr V; Rabe, Jürgen P

    2014-07-01

    The hydration of graphene oxide (GO) membranes is the key to understand their remarkable selectivity in permeation of water molecules and humidity-dependent gas separation. We investigated the hydration of single GO layers as a function of humidity using scanning force microscopy, and we determined the single interlayer distance from the step height of a single GO layer on top of one or two GO layers. This interlayer distance grows gradually by approximately 1 Å upon a relative humidity (RH) increase in the range of 2 to ?80%, and the immersion into liquid water increases the interlayer distance further by another 3 Å. The gradual expansion of the single interlayer distance is in good agreement with the averaged distance measured by X-ray diffraction on multilayered graphite oxides, which is commonly explained with an interstratification model. However, our experimental design excludes effects connected to interstratification. Instead we determine directly if insertion of water into GO occurs strictly by monolayers or the thickness of GO layers changes gradually. We find that hydration with up to 80% RH is a continuous process of incorporation of water molecules into single GO layers, while liquid water inserts as monolayers. The similarity of hydration for our bilayer and previously reported multilayered materials implies GO few and even bilayers to be suitable for selective water transport. PMID:24922580

  10. 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.

  11. Natural gas hydrates: energy for the future

    International Nuclear Information System (INIS)

    Gas clathrates (commonly called hydrates) are crystalline compounds which form when small molecules contact water at temperatures above and below the ice point, under elevated pressures. Gas hydrates of current interest are composed of water and of methane (mainly), ethane, propane or other hydrocarbons. They act to concentrate hydrocarbons: one cubic meter of hydrates may contain as much as 150-200 m3 of gas. Large natural reserves of hydrocarbons exist in hydrated form, both in deep oceans and in the permafrost. Evaluation of these reserves concurs that there is more energy in hydrated form than in all other hydrocarbon and carbon sources combined. While one commercial example exists of gas recovery form hydrates, the problem of in situ hydrate dissemination in deep water and permafrost environments will prevent their cost-effective recovery for some years

  12. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    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. Copyright 2009 by the American Geophysical Union.

  13. Stratigraphic mapping of hydrated phases in Western Ius Chasma, Mars

    Science.gov (United States)

    Cull, S.; McGuire, P. C.; Gross, C.; Dumke, A.

    2013-12-01

    Recent mapping with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) has revealed a wide range of hydrated minerals throughout Valles Marineris. Noctis Labyrinthus has interbedded polyhydrated and monohydrated sulfates, with occasional beds of nontronite (Weitz et al. 2010, Thollot et al. 2012). Tithonium Chasma has interbedded poly- and monohydrated sulfates (Murchie et al. 2012); Juventae has poly- and monohydrated sulfates and an anhydrous ferric hydroxysulfate-bearing material (Bishop et al. 2009); and Melas and Eastern Candor contain layers of poly- and monohydrated sulfates (e.g., Roach et al. 2009). Though each chasm displays its own mineralogy, in general, the eastern valles tend to be dominated by layered sequences with sulfates; whereas, the far western valles (Noctis Labyrinthus) has far more mineral phases, possibly due to a wider variety of past environments or processes affecting the area. Ius Chasma, which is situated between Noctis Labyrinthus and the eastern valles and chasmata, also displays a complex mineralogy, with polyhydrated sulfates, Fe/Mg smectites, hydrated silica, and kieserite (e.g. Roach et al. 2010). Here, we present mapping of recently acquired CRISM observations over Ius Chasma, combining the recent CRISM cubes with topographic terrains produced using High Resolution Stereo Camera (HRSC) data from the Mars Express spacecraft. Stratigraphic columns are produced along the length of Ius Chasma, and compared to stratigraphic columns produced throughout the Valles Marineris

  14. Indústria mineral

    Directory of Open Access Journals (Sweden)

    Iran F. Machado

    1998-08-01

    Full Text Available A INDÚSTRIA mineral brasileira é analisada, de modo sucinto, face aos desafios impostos pela globalização contemporânea. As mudanças profundas ocorridas no contexto internacional na última década, abrangendo as esferas política, econômica, social e institucional, exigem uma reflexão aprofundada sobre o papel a ser desempenhado pelo Brasil no comércio internacional de bens minerais. De um lado, as oportunidades de aproveitamento de jazidas de classe internacional, principalmente na Amazônia, são bastante promissoras. Por outro, não se deve ignorar que: a explotação dessas reservas terá de obedecer a critérios de sustentabilidade, seguindo paradigmas já adotados em países desenvolvidos; o Brasil terá de garantir a sua competitividade diante dos seus principais concorrentes (Austrália, CEI, China e Índia. A questão dos minerais estratégicos é também abordada, com ênfase nas preocupações demonstradas pelo Departamento de Estado dos EUA. Finalmente, são alinhados três cenários possíveis para o desempenho futuro da mineração brasileira, instando-se o governo a dedicar maior atenção ao destino do nosso subsolo.THE MINERAL industry of Brazil is briefly analysed vis-à-vis the challenges imposed by the cruenta globalization process. The profound changes that occurred in the international framework during the last decade, encompassing the political, economic, social, and institutional structures, demand a thorough appraisal about the role to be played by Brazil in the international market of mineral commodities. On one hand, the opportunities open for world class deposits, mainly in the Amazon, are very promising. On the other hand, it is mandatory to take into account that: the exploitation of these reserves shall comply with sound sustainability criteria, following guidelines already adopted by some developed countries; Brazil will have to demonstrate its competitiveness among the major competitors (Australia, China, CIS and India. The issue of strategic minerals is also discussed, giving emphasis to the concerns raised by the U.S. Department of State. Finally, three possible scenarios pointing to the future behavior of the mineral industry of Brazil are highlighted, and the government is solicited to give special consideration to our mineral resources.

  15. Indústria mineral

    Scientific Electronic Library Online (English)

    Iran F., Machado.

    1998-08-01

    Full Text Available A INDÚSTRIA mineral brasileira é analisada, de modo sucinto, face aos desafios impostos pela globalização contemporânea. As mudanças profundas ocorridas no contexto internacional na última década, abrangendo as esferas política, econômica, social e institucional, exigem uma reflexão aprofundada sobr [...] e o papel a ser desempenhado pelo Brasil no comércio internacional de bens minerais. De um lado, as oportunidades de aproveitamento de jazidas de classe internacional, principalmente na Amazônia, são bastante promissoras. Por outro, não se deve ignorar que: a explotação dessas reservas terá de obedecer a critérios de sustentabilidade, seguindo paradigmas já adotados em países desenvolvidos; o Brasil terá de garantir a sua competitividade diante dos seus principais concorrentes (Austrália, CEI, China e Índia). A questão dos minerais estratégicos é também abordada, com ênfase nas preocupações demonstradas pelo Departamento de Estado dos EUA. Finalmente, são alinhados três cenários possíveis para o desempenho futuro da mineração brasileira, instando-se o governo a dedicar maior atenção ao destino do nosso subsolo. Abstract in english THE MINERAL industry of Brazil is briefly analysed vis-à-vis the challenges imposed by the cruenta globalization process. The profound changes that occurred in the international framework during the last decade, encompassing the political, economic, social, and institutional structures, demand a tho [...] rough appraisal about the role to be played by Brazil in the international market of mineral commodities. On one hand, the opportunities open for world class deposits, mainly in the Amazon, are very promising. On the other hand, it is mandatory to take into account that: the exploitation of these reserves shall comply with sound sustainability criteria, following guidelines already adopted by some developed countries; Brazil will have to demonstrate its competitiveness among the major competitors (Australia, China, CIS and India). The issue of strategic minerals is also discussed, giving emphasis to the concerns raised by the U.S. Department of State. Finally, three possible scenarios pointing to the future behavior of the mineral industry of Brazil are highlighted, and the government is solicited to give special consideration to our mineral resources.

  16. Vitamins and Minerals

    Science.gov (United States)

    ... too much of a good thing? What Are Vitamins and Minerals? Vitamins and minerals make people's bodies ... small amounts of them each day. What Do Vitamins and Minerals Do? Vitamins and minerals boost the ...

  17. Mineral bioprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Torma, A.E.

    1993-05-01

    In the last 25 years, the introduction of biotechnological methods in hydrometallurgy has created new opportunities and challenges for the mineral processing industry. This was especially true for the production of metal values from mining wastes and low-and-complex-grade mineral resources, which were considered economically not amenable for processing by conventional extraction methods. Using bio-assisted heap, dump and in-situ leaching technologies, copper and uranium extractions gained their first industrial applications. The precious metal industries were the next to adopt the bio-preoxidation technique in the extraction of gold from refractory sulfide-bearing ores and concentrates. A variety of other bioleaching opportunities exist for nickel, cobalt, cadmium and zinc sulfide leaching. Recently developed bioremediation methods and biosorption technologies have shown a good potential for industrial applications to remove trace heavy metal and radionuclide concentrations from contaminated soils, and mining and processing effluents.

  18. Uranyl p-toluenesulphonate and its crystal hydrates. Synthesis and dehydration-hydration processes

    International Nuclear Information System (INIS)

    Lowest hydrates of uranyl p-toluenesulphonate (UPTS) and anhydrous salt were synthesised. The dehydration-hydration processes were studied by thermal gravimetric analysis. It has been established that the hydrate shell of UPTS has a layered structure. The IR spectra of UPTS and its hydrates were recorded. It was found that the IR spectra of UPTS crystal hydrates of the same composition, produced in dehydration-hydration, noticeably differ in the range of water vibrations and are the same in the range corresponding to vibrations of sulphonate groups. (author)

  19. A combined QXRD/TG method to quantify the phase composition of hydrated Portland cements

    International Nuclear Information System (INIS)

    A new method is reported for quantifying the mineral phases in hydrated cement pastes that is based on a combination of quantitative X-ray diffractometry (QXRD) and thermogravimetry (TG). It differs from previous methods in that it gives a precise measure of the amorphous phase content without relying on an assumed stoichiometric relationship between the principal hydration products, calcium hydroxide (CH) and calcium silicate hydrate (C–S–H). The method was successfully applied to gray and white ordinary Portland cements (GOPC and WOPC, respectively) that were cured for up to 56 days. Phase distributions determined by QXRD/TG closely matched those from gray-level analysis of backscattered scanning electron microscope (BSEM) images, whereas elemental compositions obtained for the amorphous phase by QXRD/TG agreed well with those measured by quantitative energy dispersive X-ray spectroscopy (EDS)

  20. Surface acid-base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides.

    Science.gov (United States)

    Yang, Xiaofang; Sun, Zhongxi; Wang, Dongsheng; Forsling, Willis

    2007-04-15

    In this paper, surface physiochemical properties of three typical aluminas, gamma-Al(OH)3, gamma-Al2O3, and alpha-Al2O3, were investigated by means of XRD, SEM, TEM, BET surface area, TG/DTA, and potentiometric titration techniques. Based on the titration data, surface protonation and deprotonation constants were determined using the constant capacitance model (CCM). The emphasis of this research was laid on the comparison of the crystal structure, surface hydration/dehydration and acid-base properties of these three typical alumina minerals. The calculation results revealed that the surface acidity of the aluminas is in the order of alpha-Al2O3>gamma-Al(OH)3>gamma-Al2O3 after being hydrated for 1 h. The correlation between the hydration/dehydration mechanisms of alumina and its acid/base properties is discussed. PMID:17275018

  1. Phyllosilicate and hydrated silica detections in the knobby terrains of Acidalia Planitia, northern plains, Mars

    Science.gov (United States)

    Pan, L.; Ehlmann, B. L.

    2014-03-01

    Here we report detections of Fe/Mg phyllosilicates and hydrated silica in discrete stratigraphic units within the knobby terrains of Acidalia Planitia made using data acquired by Compact Reconnaissance Imaging Spectrometer for Mars. Fe/Mg phyllosilicates are detected in knobs that were eroded during southward retreat of the dichotomy boundary. A second later unit, now eroded to steep-sided platforms embaying the knobs, contains hydrated silica, which may have formed via localized vapor weathering, thin-film leaching, or transient water that resulted in surface alteration. These are then overlain by smooth plains with small cones, hypothesized to be mud volcanoes which previous studies have shown to have no hydrated minerals. In spite of Acidalia's location within the putative northern ocean, collectively, the data record a history of aqueous processes much like that in the southern highlands with progressively less intensive aqueous chemical alteration from the Noachian to Amazonian.

  2. Multiple stage multiple filter hydrate store

    Science.gov (United States)

    Bjorkman, H.K. Jr.

    1983-05-31

    An improved hydrate store for a metal halogen battery system is disclosed which employs a multiple stage, multiple filter means for separating the halogen hydrate from the liquid used in forming the hydrate. The filter means is constructed in the form of three separate sections which combine to substantially cover the interior surface of the store container. Exit conduit means is provided in association with the filter means for transmitting liquid passing through the filter means to a hydrate former subsystem. The hydrate former subsystem combines the halogen gas generated during the charging of the battery system with the liquid to form the hydrate in association with the store. Relief valve means is interposed in the exit conduit means for controlling the operation of the separate sections of the filter means, such that the liquid flow through the exit conduit means from each of the separate sections is controlled in a predetermined sequence. The three separate sections of the filter means operate in three discrete stages to provide a substantially uniform liquid flow to the hydrate former subsystem during the charging of the battery system. The separation of the liquid from the hydrate causes an increase in the density of the hydrate by concentrating the hydrate along the filter means. 7 figs.

  3. Ice formation during gas hydrate decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Shahbazi, A.; Pooladi-Darvish, M. [Calgary Univ., AB (Canada)

    2009-07-01

    Much interest and research has been devoted towards the mathematical modelling of gas production from hydrate reservoirs. The 3 general techniques that can be used to recover gas from hydrate reservoirs include depressurization, thermal stimulation and inhibitor injection. All are based on breaking the stability conditions of hydrate, leading to the generation of gas. Although depressurization can be used to produce gas from hydrate reservoirs, ice formation can result in plugging. This study investigated the conditions in which ice or hydrate may form during process of hydrate decomposition. It also examined the effect of ice formation on permeability reduction. A 3-D four components simulator was developed to model hydrate decomposition and formation along with ice formation and fusion. The model incorporated energy balance, fluid flow and kinetics of the hydrate decomposition along with the ability to predict the formation of ice particles. The endothermic decomposition of hydrate particles and the Joule-Thomson effect were the two mechanisms of cooling that were investigated. This study showed that ice will not form if the bottomhole pressure is kept above the equilibrium pressure that corresponds to the freezing temperature. This point defined as the quadruple point is where methane equilibrium line and water freezing line intersect. It was concluded that ice formation may boost hydrate decomposition or gas production because it makes additional heat available in the media. 12 refs., 5 figs.

  4. Gas hydrate resources of northern Alaska

    Science.gov (United States)

    Collett, T.S.

    1997-01-01

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

  5. DISTINCTIVE FINE-SCALE MORPHOLOGY OF HYDRATE RIDGE

    Science.gov (United States)

    Conlin, D.; Paull, C. K.; Caress, D. W.; Thomas, H.; Ussler, W.; Lundsten, E.; Thompson, D.

    2009-12-01

    High-resolution multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) collected using an autonomous underwater vehicle (AUV) reveals in unprecedented detail the fine-scale morphology of the ridge crests on Hydrate Ridge, offshore Oregon. An inertial navigation system combined with a doppler velocity sonar allowed the AUV to fly pre-programmed grids with 150 m line spacing at 3 knots while maintaining an altitude of 50 m above the bottom. The data were collected on two 17.5-hour-long dives, one covering a 4.3 x 1.9 km area on the southern crest of Hydrate Ridge (769 to 930 m water depths) and the other covering a 5.2 x 2 km area on the northern crest of Hydrate Ridge (584 to 985 m water depths). These surveys cover the seafloor associated with gas hydrate research boreholes at ODP Sites 891 and 1245 to 1250). The southern crest of Hydrate Ridge is an area being considered for a cable-connected seafloor observatory. The surface of southern Hydrate Ridge is generally smooth except for two approximately circular patches with maximum diameters of 350 m and 500 m associated with a distinctive hummocky topography. The geometric relationships indicate that the edges of these patches are surrounded with small apparently erosional scarps and thus the strata exposed within the patches are stratigraphically lower than the surrounding smooth seafloor. The fine scale-topography within these patches is characterized by a highly irregular surface formed by small, sometimes circular ~0.5 m deep pits, local highs and lows separated by ~0.5 high ledges that could be formed by irregularly eroded bedding surfaces. Similar shapes also occur at larger scales. For example, a previously described feature called the “pinnacle” is a ~15 m topographic high in the center of one of these hummocky patches. The surface of northern Hydrate Ridge has similar patches of hummocky topography. However, the patches are more numerous, associated with greater relief, elongated in a NE-SW direction, and up to 1400 m long. Again, these patches appear to consist of more resistant strata that have been exposed by erosion. One crater-like feature is roughly circular with a raised rim surrounding a 40 m deep depression that is 300 m in diameter. A ridge extends over 600 m to the SW from the SW flank of this depression. This ridge has a trough near its crest that suggests it is an open crack associated with seafloor expansion formed when seafloor was up-lifted to form the ridge. Previous ROV and manned submersible dives indicate that methane-derived carbonates, chemosynthetic biological communities and near seafloor gas hydrate occurrences are associated with the patches of seafloor we now know are characterized by the distinctive hummocky topography. Apparently, these distinctive textures and seafloor features are produced by processes which are focused at methane-rich seafloor sites; however, previously available survey tools have not had the resolution to adequately image these features.

  6. Attraction between hydrated hydrophilic surfaces

    Science.gov (United States)

    Kandu?, Matej; Schneck, Emanuel; Netz, Roland R.

    2014-08-01

    According to common knowledge, hydrophilic surfaces repel via hydration forces while hydrophobic surfaces attract, but mounting experimental evidence suggests that also hydrophilic surfaces can attract. Using all-atom molecular dynamics simulations at prescribed water chemical potential we study the crossover from hydration repulsion to hydrophobic attraction for planar polar surfaces of varying stiffness and hydrogen-bonding capability. Rescaling the partial charges of the polar surface groups, we cover the complete spectrum from very hydrophobic surfaces (characterized by contact angles ? ? 135°) to hydrophilic surfaces exhibiting complete wetting (? = 0°). Indeed, for a finite range ?adh sub-nanometer separation and stably adhere without intervening water. The adhesive contact angle ?adh depends on surface type and lies in the range 65°

  7. Molecular Structure of Acyclovir hydrate

    Science.gov (United States)

    2002-09-12

    Acyclovir hydrate is used in the treatment of shingles and herpes simplex virus and as well as other types of herpes viral infections. This may help people co-infected with HIV and herpes simplex live longer. High dose acyclovir is used to treat hairy leukoplakia, a viral infection which usually shows up on both sides of the tongue. Possible side effects of this therapeutic substance are stomach pain, headache, nausea and/or hair-loss.

  8. Early hydration of cementitious systems

    OpenAIRE

    Juilland, Patrick

    2009-01-01

    Underground job sites such as tunnels and mines rely on the quality of recently sprayed concrete to secure freshly excavated zones. Rapid setting and early high strength development are required for safety as well as for the rapid progression of the construction site. This is ensured by the addition of accelerating admixtures. These admixtures are of various chemical formulations and have different impacts on the early hydration kinetics. It is therefore important to understand their impact o...

  9. Radon risk in ore miners

    International Nuclear Information System (INIS)

    Underground workers are exposed to various clastogenic agents. One of these agents, radon, attracts attention of recent research as it causes lung cancer in the population occupationally exposed to its various concentrations especially in mine air of uranium mines or ore mines. This paper is a pilot study in which the numbers of chromosomal aberrations (CA) in lymphocytes of ore mines (Nizna Slana-iron ore, Hnusta-talc ore) located in east central Slovakia were followed and related to the lifetime underground radon exposure and to lifetime smoking. Seventy miners volunteering after an informed consent served as donors of venous blood. Twenty healthy pro-bands, age matched with the miners, which never worked underground (mostly clerks) served as donors of control blood samples. The exposure to radon and smoking has been estimated according to working-records and personal anamnesis. The findings unequivocally showed a small but statistically significant clastogenic effect of the exposure to underground environment of the mines concerned. This study has shown also a small but significant influence of smoking, which in the subgroup of miners working underground less than 1500 shifts may have acted synergically with the underground exposure. It was concluded tat: (1) Significantly higher counts of chromosomal aberrations in lymphocytes of 70 miners than in an age matched control group of 20 white-collar workers were found; (2) The higher counts of chromosomal aberrations could be ascribed to underground exposure of miners and to smoking; (3) The positive dependence of the number of chromosomal aberrations from the exposure to smoking was loose and it was expressed by significantly higher chromosomal aberrations counts in the group of miners working less than 1500 shifts underground; (4) A dependence of chromosomal aberrations counts from the exposure to radon could not be assessed. At relatively low numbers of pro-bands in subgroups it was not ruled out the confounding of such dependence by smoking which in this study showed to be a risk could not be neglected

  10. Gas hydrates: Technology status report

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    In 1983, the US Department of Energy (DOE) assumed the responsibility for expanding the knowledge base and for developing methods to recover gas from hydrates. These are ice-like mixtures of gas and water where gas molecules are trapped within a framework of water molecules. This research is part of the Unconventional Gas Recovery (UGR) program, a multidisciplinary effort that focuses on developing the technology to produce natural gas from resources that have been classified as unconventional because of their unique geologies and production mechanisms. Current work on gas hydrates emphasizes geological studies; characterization of the resource; and generic research, including modeling of reservoir conditions, production concepts, and predictive strategies for stimulated wells. Complementing this work is research on in situ detection of hydrates and field tests to verify extraction methods. Thus, current research will provide a comprehensive technology base from which estimates of reserve potential can be made, and from which industry can develop recovery strategies. 7 refs., 3 figs., 6 tabs.

  11. The chemical composition of mineral trioxide aggregate

    Directory of Open Access Journals (Sweden)

    Camilleri Josette

    2008-01-01

    Full Text Available Mineral trioxide aggregate (MTA is composed of Portland cement, with 4:1 addition of bismuth oxide added so that the material can be detected on a radiograph. The cement is made up of calcium, silicon and aluminium. The main constituent phases are tricalcium and dicalcium silicate and tricalcium aluminate. There are two commercial forms of MTA, namely the grey and the white. The difference between the grey and the white materials is the presence of iron in the grey material, which makes up the phase tetracalcium alumino-ferrite. This phase is absent in white MTA. Hydration of MTA occurs in two stages. The initial reaction between tricalcium aluminate and water in the presence of calcium sulphate results in the production of ettringite. Tricalcium and dicalcium silicate react with water to produce calcium silicate hydrate and calcium hydroxide, which is leached out of the cement with time.

  12. The chemical composition of mineral trioxide aggregate.

    Science.gov (United States)

    Camilleri, Josette

    2008-10-01

    Mineral trioxide aggregate (MTA) is composed of Portland cement, with 4:1 addition of bismuth oxide added so that the material can be detected on a radiograph. The cement is made up of calcium, silicon and aluminium. The main constituent phases are tricalcium and dicalcium silicate and tricalcium aluminate. There are two commercial forms of MTA, namely the grey and the white. The difference between the grey and the white materials is the presence of iron in the grey material, which makes up the phase tetracalcium alumino-ferrite. This phase is absent in white MTA. Hydration of MTA occurs in two stages. The initial reaction between tricalcium aluminate and water in the presence of calcium sulphate results in the production of ettringite. Tricalcium and dicalcium silicate react with water to produce calcium silicate hydrate and calcium hydroxide, which is leached out of the cement with time. PMID:20351970

  13. Development of Alaskan gas hydrate resources

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  14. Multicomponent modelling of Portland cement hydration reactions:

    OpenAIRE

    Ukrainczyk, N.; Koenders, E. A. B.; 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 service life. In this paper the multicomponent model of portland cement hydration reactions is implemented within the original Hymostruc model. The reaction kinetics of the four principal clinker min...

  15. Lectures held at the congress on ``Gas hydrates: problem substance / resource``, organised by the GDMK Division for ``Exploration and Extraction`` and the Institute for Mineral Oil and Natural Gas Research, in Clausthal-Zellerfeld (Harz) on 6/7 November 1997. Author`s manuscripts; Vortraege der Veranstaltung ``Gashydrate: Problemstoff/Resource`` des GDMK-Fachbereichs `Aufsuchung und Gewinnung` und dem Institut fuer Erdoel- und Erdgasforschung am 06. und 07. November 1997 in Clausthal-Zellerfeld (Harz). Autorenmanuskripte

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The following topics are dealt with in detail: the chemical and physical properties of gas hydrates as derivable from their phase behaviour; the significance and occurrence of gas hydrates in offshore areas; gas hydrates and permafrost in continental northern West Siberia; information on HYACE, a research project of the European Union on test drilling for gas hydrates in offshore areas; sediment-mechanical criteria of gas hydrate formation in deep-sea sediments; gas hydrate formation in gas cavern storages; the use of hydrate inhibitors in operating natural gas storages; and the inhibition of gas hydrates with kinetic inhibitors. Eight abstracts were abstracted individually for the Energy Database. (MSK) [Deutsch] Folgende Themen werden detailliert behandelt: die chemischen und physikalischen Eigenschaften von Gashydraten,welche aus dem Phasenverhalten der Gashydrate herzuleiten sind; zur Bedeutung und Vorkommen von Gashydraten im Offshore-Bereich; Gashydrate und Permafrost im kontinentalen noerdlichen Westsibirien; Informationen zu HYACE, einem Forschungsprojekt der Europaeischen Union zu Probebohrungen nach Gashydraten im Offshore-Bereich; sedimentmechanische Kriterien bei der Gashydratbildung in Tiefseesedimenten; die Gashydratbildung in Gaskavernenspeichern; der Einsatz von Hydratinhibitoren beim Betrieb von Erdgasspeichern sowie die Inhibierung von Gashydraten mit kinetischen Inhibitoren. Fuer die Datenbank Energy wurden acht Beitraege einzeln aufgenommen.

  16. Hydrated calcareous oil-shale ash as potential filter media for phosphorus removal in constructed wetlands.

    Science.gov (United States)

    Kaasik, Ago; Vohla, Christina; Mõtlep, Riho; Mander, Ulo; Kirsimäe, Kalle

    2008-02-01

    The P-retention in hydrated calcareous ash sediment from oil-shale burning thermal power plants in Estonia was studied. Batch experiments indicate good (up to 65 mg P g(-1)) P-binding capacity of the hydrated oil-shale ash sediment, with a removal effectiveness of 67-85%. The high phosphorus sorption potential of hydrated oil-shale ash is considered to be due to the high content of reactive Ca-minerals, of which ettringite Ca6Al2(SO4)3(OH)12.26H2O and portlandite Ca(OH)2 are the most important. The equilibrium dissolution of ettringite provides free calcium ions that act as stable nuclei for phosphate precipitation. The precipitation mechanism of phosphorus removal in hydrated ash plateau sediment is suggested by Ca-phosphate formation in batch experiments at different P-loadings. Treatment with a P-containing solution causes partial-to-complete dissolution of ettringite and portlandite, and precipitation of Ca-carbonate and Ca-phosphate phases, which was confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM)-EDS studies. Thus, the hydrated oil-shale ash sediment can be considered as a potential filtration material for P removal in constructed wetlands for wastewater treatment. PMID:17959214

  17. Stiffening effects of riboflavin/UVA corneal collagen cross-linkingis hydration dependent.

    Science.gov (United States)

    Hatami-Marbini, H; Rahimi, A

    2015-04-13

    The collagen cross-linking is a relatively new treatment option for strengthening the cornea, delaying, and in some cases stopping the progression of keratoconus. The uniaxial tensile experiments are among the most commonly used techniques to assess the effectiveness of this therapeutic option in enhancing tensile properties. In the present study, we investigated the possible effects of hydration on stiffening effects of corneal collagen cross-linking procedure, as measured by the uniaxial tensile testing method. For this purpose, after cross-linking bovine corneas, we let the strips to dehydrate in air or swell in a solution until their thickness reached an average thickness of 0.5, 0.7, 0.9, 1.1, and 1.5mm. Using thickness as a representative of hydration, we divided corneal strips into five different groups and measured their stress-strain behavior by conducting uniaxial tensile experiments in mineral oil. It was observed that the collagen cross-linking treatment and hydration together affect the tensile behavior of the bovine cornea. While corneal collagen cross-linking resulted in a significant increase in the tensile stress-strain response of each thickness group (P<0.01), less hydrated collagen cross-linked samples showed a significantly stiffer response (P<0.01). A master curve was found for representing the tensile behavior of the collagen cross-linked bovine cornea at different levels of hydration. The results of the present research confirmed that the amount of mechanical stiffening of the corneal collagen cross-linking, as measured by uniaxial tensile testing, strongly depends on the hydration. Therefore, it is concluded that uniaxial tensile experiments could only be used to assess stiffening effects of the collagen cross-linking treatment if the hydration of specimens is fully controlled. PMID:25704532

  18. Experimental investigation of smectite hydration from the simulation of 001 X-ray diffraction lines. Implications for the characterization of mineralogical modifications of the 'argilite' from the Meuse - Haute Marne site as a result of a thermal perturbation

    International Nuclear Information System (INIS)

    The structural modifications affecting the reactive mineral constituents of the clay barriers (smectite) and possibly resulting from the thermal pulse related to nuclear waste storage are essentially limited to the amount and location of the layer charge deficit. These modifications likely impact the hydration properties of these minerals, and a specific methodology has thus been developed to describe, using simulation of X-ray diffraction profiles (001 reflections), these hydration properties and specifically the heterogeneity resulting from the inter-stratification of different layer types, each exhibiting a specific hydration state. The detailed study of the hydration properties of a low-charge montmorillonite (octahedral charge) has shown that the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. If the layer charge is increased, the transition between the different hydration states is shifted, following a water desorption isotherm, towards lower relative humidities. In addition, the hydration of studied beidellites (tetrahedral charge) was shown to be more heterogeneous than that of montmorillonites. The developed methodology also allowed describing the structural modifications resulting from a chemical perturbation (chlorinated anionic background, pH). Finally, the link between the thickness of elementary layers and the amount of interlayer water molecules has been evidenced. A new structure model has also been determined for these interlayer species allowing an improved description of their positional distribution in bi-hydrated interlayers. (author)

  19. Methane hydrates as potential energy resource: Part 2 - Methane production processes from gas hydrates

    International Nuclear Information System (INIS)

    Three processes have been proposed for dissociation of methane hydrates: thermal stimulation, depressurization, and inhibitor injection. The obvious production approaches involve depressurization, heating and their combinations. The depressurization method is lowering the pressure inside the well and encouraging the methane hydrate to dissociate. Its objective is to lower the pressure in the free-gas zone immediately beneath the hydrate stability zone, causing the hydrate at the base of the hydrate stability zone to decompose. The thermal stimulation method is applied to the hydrate stability zone to raise its temperature, causing the hydrate to decompose. In this method, a source of heat provided directly in the form of injected steam or hot water or another heated liquid, or indirectly via electric or sonic means. This causes methane hydrate to decompose and generates methane gas. The methane gas mixes with the hot water and returns to the surface, where the gas and hot water are separated. The chemical inhibition method seeks to displace the natural-gas hydrate equilibrium condition beyond the hydrate stability zone's thermo-dynamic conditions through injection of a liquid inhibitor chemical adjacent to the hydrate. In this method, inhibitor such as methanol is injected from surface down to methane hydrate-bearing layers. The thermal stimulation method is quite expensive. The chemical inhibitor injection method is also expensive. The depressurization method may pronsive. The depressurization method may prove useful to apply more than one production.

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

    Science.gov (United States)

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

    2013-12-27

    The effect of the concentration of kinetic hydrate inhibitors, polyvinylpyrrolidone (PVP), and polyvinylcaprolactam (PVCap) on the onset and growth of synthetic natural gas hydrates is investigated by measuring the hydrate onset time and gas consumption rate. Although the hydrate onset time is extended by increasing the concentration from 0.5 to 3.0 wt % for both PVP and PVCap, the growth rate of hydrates shows that the different tendency depends on the type of kinetic hydrate inhibitor and its concentration. For PVCap solution, the hydrate growth was slow for more than 1000 min after the onset at the concentration of 0.5 and 1.5 wt %. However, the growth rate becames almost 8 times faster at the concentration of 3.0 wt %, representing the catastrophic growth of hydrate just after the hydrate onset. (13)C NMR spectra of hydrates formed at 3.0 wt % of PVP and PVCap indicate the existence of both structures I and II. Cage occupancy of methane in large cages of structure II decreases significantly when compared to that for pure water. These results suggest that increasing the concentration of KHI up to 3.0 wt % may induce the earlier appearance of catastrophic hydrate growth and the existence of metastable structure I; thus, there needs to be an upper limit for using KHI to manage the formation of gas hydrates. PMID:24295438

  1. Effects of different mineral admixtures on the properties of fresh concrete.

    Science.gov (United States)

    Khan, Sadaqat Ullah; Nuruddin, Muhammad Fadhil; Ayub, Tehmina; Shafiq, Nasir

    2014-01-01

    This paper presents a review of the properties of fresh concrete including workability, heat of hydration, setting time, bleeding, and reactivity by using mineral admixtures fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA). Comparison of normal and high-strength concrete in which cement has been partially supplemented by mineral admixture has been considered. It has been concluded that mineral admixtures may be categorized into two groups: chemically active mineral admixtures and microfiller mineral admixtures. Chemically active mineral admixtures decrease workability and setting time of concrete but increase the heat of hydration and reactivity. On the other hand, microfiller mineral admixtures increase workability and setting time of concrete but decrease the heat of hydration and reactivity. In general, small particle size and higher specific surface area of mineral admixture are favourable to produce highly dense and impermeable concrete; however, they cause low workability and demand more water which may be offset by adding effective superplasticizer. PMID:24701196

  2. Constraining clay hydration state and its role in active fault systems

    Science.gov (United States)

    Schleicher, Anja M.; Hofmann, Heiko; Pluijm, Ben A.

    2013-04-01

    understand the role of hydrated clay minerals in active fault systems, a humidity chamber connected to an X-ray diffractometer was used to determine the adsorption of water onto and/or into the crystal structure of smectite. This new type of analysis was carried out under specific temperature and humidity conditions, using powdered clay size fractions (San Andreas Fault (USA) and the Nankai Trough (Japan). Pressure cannot be controlled, but does not significantly affect clay swelling at shallow conditions. Air-dried samples show a discrete smectite phase that swells after traditional ethylene glycolation to an interlayer distance of 1.5 and 1.7 nm. Using the humidity chamber, however, the samples show a shorter interlayer distance, between 1.09 and 1.54 nm. Based on our analysis, we show that (i) ethylene glycol overestimates the size of the interlayer space, and therefore water content, so is a crude maximum only; (ii) interlayer swelling occurs in smectite clay minerals at all temperatures between 25 and 95°C; and (iii) particle orientation increases with increasing humidity, indicating a higher mobility of smectite from interlayer hydration. Detailed characterization of the hydration state of smectite under original conditions is critical for understanding of clay-fluid interaction, the mechanical behavior during fault displacements, and fluid budgets at depth. We propose that humidity chamber experiments should be the new standard procedure to constrain swelling characteristics of natural and synthetic clay minerals.

  3. Quick Assessment of Potential Hydrate Promoters for Rapid Formation

    OpenAIRE

    Lo, Chi Y.; Somasundaran, P.; Lee, Jae W.

    2012-01-01

    Hydrate technology has advanced to greater proportions: implementing the high latent heats as refrigerant, safe carbon capture as carbon sequestration in hydrates, purifying rare gases in hydrates, and safe efficient transport of energy using rapid hydrate formation. These account for only a small amount of the fundamental understanding of gas hydrates and the use of such a novel technology. A quick and broad analysis of novel hydrate promoters is needed to assess the potential of other promo...

  4. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Cristiano Ralo Monteiro

    2003-08-01

    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.

  5. Hydration in soccer: a review

    Scientific Electronic Library Online (English)

    Cristiano Ralo, Monteiro; Isabela, Guerra; Turíbio Leite de, Barros.

    2003-08-01

    Full Text Available SciELO Brazil | Language: English Abstract in english 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 acclimatiza [...] tion; 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.

  6. Synthesis, dehydration and hydration processes of uranyl p-toluenesulfonate and its crystal hydrates

    International Nuclear Information System (INIS)

    Uranyl p-toluenesulfonate was synthesized and studied. This salt crystallizes from aqueous solution as pentahydrate. Its solubility is 2.57 mol/kg at 25 Deg C. Anhydrous salt and lower hydrates were prepared. Hydration of the anhydrous salt in the air at various steam pressures are studied. Thermogravimetric data show that uranyl p-toluenesulfonate pentahydrate has the layered structure of hydration shell. IR spectra of crystal hydrates with the same composition obtained by means of dehydration-hydration procedure are the same in the region of frequencies of sulfonate group and differ in the region of water vibrations

  7. Hydration mechanisms of silicate glasses

    International Nuclear Information System (INIS)

    The comparative leaching behavior of a soda-lime glass and of a simulated nuclear glass has been investigated through H and Na depth profiles obtained with resonant nuclear reaction analysis. It is shown that glass surface hydration involves both H+/Na+ ion exchange and permeation of molecular water, the first process being dominant at low temperature and solution ionic strength and the second for high values of these two parameters. The shape of the H profile as well as the response of H retention to thermal treatment indicate that on the nuclear glass, most of the molecular water is more weakly bonded that on the soda-lime glass

  8. Hydration modeling of calcium sulphates

    OpenAIRE

    Korte, A. C. J.; Brouwers, H. J. H.

    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 transitions between the different calcium sulphate phases (anhydrite, hemihydrate and gypsum). Besides that gypsum was seen as intermediate phase instead of a final phase. The presented model addresses...

  9. Hydration behaviour of polyhydroxylated fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Zavala, J G [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de Los Lagos, Universidad de Guadalajara, Enrique Diaz de Leon S/N, 47460 Jalisco (Mexico); Barajas-Barraza, R E [Departamento de Matematicas y Fisica, Instituto Tecnologico y de Estudios Superiores de Occidente, Periferico Sur, Manuel Gomez MorIn No 8585, 45604 Jalisco (Mexico); Padilla-Osuna, I; Guirado-Lopez, R A, E-mail: jgrz@culagos.udg.mx, E-mail: ebarajas@iteso.mx, E-mail: ismael@ifisica.uaslp.mx, E-mail: guirado@ifisica.uaslp.mx [Instituto de Fisica ' Manuel Sandoval Vallarta' , Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2011-10-28

    We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C{sub 60} and highly hydroxylated C{sub 60}(OH){sub 26} fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C{sub 60}, water adsorption reveals that the H{sub 2}O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C{sub 60} structure. In contrast, in the polyhydroxylated C{sub 60}(OH){sub 26} fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C{sub 60}(OH){sub 26} compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C{sub 60}(OH){sub 26} isomers can change in the presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H{sub 2}O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C{sub 60}(OH){sub 26} isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C{sub 60}(OH){sub 26} structures in the presence and absence of water molecules, we note that only slight variations in the position and intensity of the electronic excitations are found, indicating that their vacuum optical properties are more or less preserved in aqueous environments.

  10. Hydration behaviour of polyhydroxylated fullerenes

    International Nuclear Information System (INIS)

    We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C60 and highly hydroxylated C60(OH)26 fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C60, water adsorption reveals that the H2O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C60 structure. In contrast, in the polyhydroxylated C60(OH)26 fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C60(OH)26 compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C60(OH)26 isomers can change in the presence of water. The radial distributhe presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H2O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C60(OH)26 isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C60(OH)26 structures in the presence and absence of water molecules, we note that only slight variations in the position and intensity of the electronic excitations are found, indicating that their vacuum optical properties are more or less preserved in aqueous environments.

  11. Hydrothermal hydration of Martian crust: illustration via geochemical model calculations.

    Science.gov (United States)

    Griffith, L L; Shock, E L

    1997-04-25

    If hydrothermal Systems existed on Mars, hydration of crustal rocks may have had the potential to affect the water budget of the planet. We have conducted geochemical model calculations to investigate the relative roles of host rock composition, temperature, water-to-rock ratio, and initial fluid oxygen fugacity on the mineralogy of hydrothermal alteration assemblages, as well as the effectiveness of alteration to store water in the crust as hydrous minerals. In order to place calculations for Mars in perspective, models of hydrothermal alteration of three genetically related Icelandic volcanics (a basalt, andesite, and rhyolite) are presented, together with results for compositions based on SNC meteorite samples (Shergotty and Chassigny). Temperatures from 150 degrees C to 250 degrees C, water-to-rock ratios from 0.1 to 1000, and two initial fluid oxygen fugacities are considered in the models. Model results for water-to-rock ratios less than 10 are emphasized because they are likely to be more applicable to Mars. In accord with studies of low-grade alteration of terrestrial rocks, we find that the major controls on hydrous mineral production are host rock composition and temperature. Over the range of conditions considered, the alteration of Shergotty shows the greatest potential for storing water as hydrous minerals, and the alteration of Icelandic rhyolite has the lowest potential. PMID:11541456

  12. Effect of clay minerals on the stabilization of black cotton and lateritic soils

    International Nuclear Information System (INIS)

    The problem associated with black cotton and lateritic soils because of the swelling-shrinkage property of their constituent clay minerals were investigated. Samples of black cotton lateritic soils were collected from different parts of Kenya. The samples were analysed for their mineral compositions and later treated with hydrated lime in order to eliminate the swelling shrinkage behaviour. The samples were subsequently tested for their engineering properties in a soil mechanics laboratory using shear box and Casagrande apparatus. It was found that the chemical treatment of the soils with hydrated lime removes their plastic property and improves their shear strength. (author)

  13. Bone Mineral “Quality”: Differing Characteristics of Calcified Microsphere Populations at the Osteoporotic and Osteoarthritic Femoral Articulation Front

    Directory of Open Access Journals (Sweden)

    Kathryn M. Linton

    2014-07-01

    Full Text Available The mineral front consists of large populations of organically enshrouded calcified microspheres (filamentous clusters about 1 micron in diameter and associated smaller numbers of variably dense nanospheres, 30 - 40 nm in diameter. The discrete objects persist and modulate in maturity, and may constitute a variable “qualitative” factor in the skeletal inorganic phase, exemplified by the biomechanically contrasting pathologies of osteoporosis (OP; fracture, low stress condition and osteoarthritis (OA; non fracture, high stress condition. The aim was to compare the articulation front material for morphological and trace element diversity using fresh female femoral head discards (from Dewsbury District Hospital NHS Mid-Yorkshire Trust. These were prepared for histology of the cartilage/bone interface region by immersion in hydrazine hydrate to expose the anorganic mineral topography for microscopy and FEGSEM microanalysis. 1 Mineral microsphere morphology (compared to animals as arbitrary controls suggested that calcified microspheres from OP (n = 19 tended to be small (0.5 - 0.7 microns, smooth and compacted; those from OA (n = 19 were large (0.5 - 4.0 microns, uneven and irregularly dispersed. Respective calcified nanospheres from OP were similarly smaller (30 - 50 nm than those from OA (>100 nm. In subchondral bone a proportion of the filamentous microspheres had fused into a fine-textured phase in OP and a coarse-textured phase in OA. 2 Trace element analysis (compared to positive porcine Si and Mg and other peaks suggested a diminution with mineral maturity, and also with age effecting OP and OA similarly, with minor differences detected between them. It was concluded that calcified objects constituting the inorganic phase vary regionally with age and in fracture and nonfracture, being diminished in size (not number in weak OP and enlarged (compared to porcine control in stronger OA, with Si or Mg “doping” diminishing with time, perhaps influencing their individual bioactivity and matrix dynamics.

  14. Evaluation of hydration indexes in kale leaves

    Scientific Electronic Library Online (English)

    Adonai G., Calbo; Marcos D., Ferreira.

    Full Text Available SciELO Brazil | Language: English Abstract in english Hydration indexes are practical variables for quantifying plant water stress and can be useful for agronomic purposes. Three adapted hydration indexes based on relative water content, volumetric hydration, and leaf turgor pressure were evaluated in kale (Brassica oleracea var. acephala) leaf segment [...] s. Relative water content and volumetric hydration were measured in leaf segments after a water infiltration procedure with the aim of filling its large intercellular volumes (@18%v/v). The infiltration was done using a hydrostatic weighing procedure and with the aid of vacuum to fully hydrate the leaf segments. These two relative indexes were proportional to the transpiration-induced leaf water loss. The third index, turgor pressure, was measured with a Wiltmeter® instrument. Similarly, the turgor pressure was proportional to the leaf water loss, and it decreased from @310kPa in recently harvested leaves to zero in dehydrated leaves, after a total water loss of @23%. Turgor pressure was correlated with the other two hydration indexes using approximations of leaf volumetric elastic modules. Similar estimates were obtained because the decline between turgor pressure and the natural logarithm of these relative leaf hydration indexes was numerically similar (@900kPa). However, the volumetric hydration index seemed to be more suitable as a model, not only for being more concise but also because it showed a clearer biomechanical representation of the leaf water deficit effects.

  15. Evaluation of hydration indexes in kale leaves

    Directory of Open Access Journals (Sweden)

    Adonai G. Calbo

    2011-01-01

    Full Text Available Hydration indexes are practical variables for quantifying plant water stress and can be useful for agronomic purposes. Three adapted hydration indexes based on relative water content, volumetric hydration, and leaf turgor pressure were evaluated in kale (Brassica oleracea var. acephala leaf segments. Relative water content and volumetric hydration were measured in leaf segments after a water infiltration procedure with the aim of filling its large intercellular volumes (@18%v/v. The infiltration was done using a hydrostatic weighing procedure and with the aid of vacuum to fully hydrate the leaf segments. These two relative indexes were proportional to the transpiration-induced leaf water loss. The third index, turgor pressure, was measured with a Wiltmeter® instrument. Similarly, the turgor pressure was proportional to the leaf water loss, and it decreased from @310kPa in recently harvested leaves to zero in dehydrated leaves, after a total water loss of @23%. Turgor pressure was correlated with the other two hydration indexes using approximations of leaf volumetric elastic modules. Similar estimates were obtained because the decline between turgor pressure and the natural logarithm of these relative leaf hydration indexes was numerically similar (@900kPa. However, the volumetric hydration index seemed to be more suitable as a model, not only for being more concise but also because it showed a clearer biomechanical representation of the leaf water deficit effects.

  16. Kinetics of gas hydrate nucleation and growth

    OpenAIRE

    Abay, Hailu Kebede

    2011-01-01

    PAPER 4: Hailu K. Abay and Thor M. Svartaas, On the Kinetics of Methane HydrateFormation: A Time-dependent Kinetic Rate Model, Proceedings of the 7thInternational Conference on Gas Hydrates, Edinburgh, United Kingdom,July 17-21, 2011. http://www.icgh.org/

  17. Gas hydrates in the ocean environment

    Science.gov (United States)

    Dillon, William P.

    2002-01-01

    A GAS HYDRATE, also known as a gas clathrate, is a gas-bearing, icelike material. It occurs in abundance in marine sediments and stores immense amounts of methane, with major implications for future energy resources and global climate change. Furthermore, gas hydrate controls some of the physical properties of sedimentary deposits and thereby influences seafloor stability.

  18. Diffusion of CO2 During Hydrate Formation and Dissolution; A

    International Nuclear Information System (INIS)

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

  19. Effect of Zeolite for Methane Hydrate Formation

    International Nuclear Information System (INIS)

    Methane hydrate is formed by physical binding between water molecules and gases such as methane, ethane, propane, or carbon dioxide, etc., which are captured in the cavities of water molecules 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 m3 hydrate of pure methane can be decomposed to the maximum of 216 m3 methane at standard condition. If these characteristics of hydrate are reversely utilized, the 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 that of 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 apple, for the practical purpose in the application, the present investigation is focused on the rapid production of hydrates and on the increases of gas consumption by adding natural zeolite into pure water. The results of the study show that the equilibrium pressure in natural zeolite is more lower than that in distilled water, and methane hydrate could be formed rapidly during pressurization, if the subcooling is maintained at 8K or above in distilled water and 6.5K or above in natural zeolite, respectively. Also, the amount of consumed gas volume in natural zeolite is more higher than in distilled water at the same experimental conditions. Also, when the natural zeolite of 0.01 wt% was added to distilled water, the amount of consumed gas was about four times higher than that in distilled water and the hydrate formation time decreased at the low subcooling temperature. Therefore, it is found that natural zeolite acts as a catalyst in hydrate formation

  20. 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 revolutionary and new Arctic Drilling Platform in search of gas hydrate and free gas accumulations at depths of approximately 1200 to 2500 ft MD. A secondary objective was the gas-charged sands of the uppermost Campanian interval at approximately 3000 ft. Summary results of geophysical analysis of the well are presented in this report.

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

    Science.gov (United States)

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

    2007-12-01

    Natural processes that separate materials from a mixture may exert a major influence on the development of the atmospheres and surfaces of planets, moons, and other planetary bodies. Natural distillation and gravity separation, amongst others, are well known means of differentiating materials through liquid-gas partitioning. One of the least known attributes of clathrate (gas) hydrates is their potential effect on the evolution of planetary system oceans and atmospheres. Gas hydrates separate gases from mixtures of gases by concentrating preferred hydrate-forming materials (HFM) guests within the water-molecule cage structure of crystalline hydrate. Different HFMs have very different fields of stability. When multiple hydrate formers are present, a preference series based on their selective uptake exists. Compound hydrate, which is formed from two or more species of HFM, extract preferred HFM from a mixture in very different proportions to their relative percentages of the original mixture. These compound hydrates can have different formation and dissociation conditions depending on the evolution of the environment. That is, the phase boundary of the compound hydrate that is required for dissociation lies along a lower pressure - higher temperature course. Compound hydrates respond to variations in temperature, pressure, and HFM composition. On Earth, the primary naturally occurring hydrate of interest to global climate modeling is methane hydrate. Oceanic hydrate on Earth is the largest store of carbon in the biosphere that is immediately reactive to environmental change, and is capable of releasing large amounts of methane into the atmosphere over a short geological time span. Hydrate formation is essentially metastable and is very sensitive to environmental change and to gas flux. Where natural variations in temperature and pressure varies so that hydrate will form and dissociate in some cyclical manner, such as in oceans where sea level is capable of rising and falling, and which warms and cools, and in atmospheres in which temperature swings take place, the compound hydrate system can both sequester and release HFM selectively. When there is strong gas flux hydrate will tend to form; when gas flux falls below a certain level, hydrate may either dissolve or dissociate. On other bodies in the solar system, such as on Titan, ethane, propane, nitrogen, noble gases, and other HFMs may be selectively withdrawn from gas and liquid phases and sequestered within hydrate, or selectively released when climate swings occur, which can cause positive or negative feedback to atmospheric composition and greenhouse intensity. Where carbon-based biosphere conditions exist, the hydrate system will interact with it in the same manner as it does on Earth.

  2. Experimental Setup to Characterize Bentonite Hydration Processes

    International Nuclear Information System (INIS)

    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

  3. Methane hydrates in the Chilean continental margin

    Scientific Electronic Library Online (English)

    Esteban, Morales G..

    2003-08-15

    Full Text Available SciELO Chile | Language: English Abstract in english In the coming years the worldwide energetic resources based on hydrocarbons will diminish, and methane hydrates can become an alternative source, given its huge deposits. Chile does not have great amounts of energetic resources; however, during the cruise C-2901 on board the R/V CONRAD in 1998, seis [...] mic profiles that took place in the Chilean continental margin between 35º and 45ºS show the presence of methane hydrates through BSR analysis. The following parameters for the hydrate layer can be assumed: Thickness = 100 m, Longitude E-W = 20 km, Latitude N-S = 1000 km, hydrate concentration in the sediments = 10%, and 160 m³ of gas per m³ of hydrate. With these figures, the volume of estimated gas is 3.2 x 10(13) m³.

  4. Hydration Dynamics of Aqueous Nitrate

    DEFF Research Database (Denmark)

    ThØgersen, Jan; Réhault, Julien

    2013-01-01

    Aqueous nitrate, NO3(-)(aq), was studied by 2D-IR, UV-IR, and UV-UV time-resolved spectroscopies in combination with molecular dynamics (MD) simulations with the purpose of determining the hydration dynamics around the anion. In water, the D3h symmetry of NO3(-) is broken, and the degeneracy of the asymmetric-stretch modes is lifted. This provides a very sensitive probe of the ion-water interactions. The 2D-IR measurements reveal excitation exchange between the two nondegenerate asymmetric-stretch vibrations on a 300-fs time scale concomitant with fast anisotropy decay of the diagonal-peak signals. The MD simulations show that this is caused by jumps of the transition dipole orientations related to fluctuations of the hydrogen bonds connecting the nitrate ion to the nearest water molecules. Reorientation of the ion, which is associated with the hydrogen-bond breaking, was monitored by time-resolved UV-IR and UV-UV spectroscopy, revealing a 2-ps time constant. These time scales are very similar to those reported for isotope-labeled water, suggesting that NO3(-)(aq) has a labile hydration shell.

  5. Chemical and physical transformations of aluminosilicate clay minerals due to acid treatment and consequences for heterogeneous ice nucleation.

    Science.gov (United States)

    Sihvonen, Sarah K; Schill, Gregory P; Lyktey, Nicholas A; Veghte, Daniel P; Tolbert, Margaret A; Freedman, Miriam Arak

    2014-09-25

    Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing of dust during atmospheric transport can alter its ice nucleation activity. In particular, several recent studies have noted that sulfuric and nitric acids inhibit heterogeneous ice nucleation in the regime below liquid water saturation in aluminosilicate clay minerals. We have exposed kaolinite, KGa-1b and KGa-2, and montmorillonite, STx-1b and SWy-2, to aqueous sulfuric and nitric acid to determine the physical and chemical changes that are responsible for the observed deactivation. To characterize the changes to the samples upon acid treatment, we use X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. We find that the reaction of kaolinite and montmorillonite with aqueous sulfuric acid results in the formation of hydrated aluminum sulfate. In addition, sulfuric and nitric acids induce large structural changes in montmorillonite. We additionally report the supersaturation with respect to ice required for the onset of ice nucleation for these acid-treated species. On the basis of lattice spacing arguments, we explain how the chemical and physical changes observed upon acid treatment could lead to the observed reduction in ice nucleation activity. PMID:25211030

  6. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-06-01

    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. 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.

  7. Overview on Hydrate Coring, Handling and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jon Burger; Deepak Gupta; Patrick Jacobs; John Shillinglaw

    2003-06-30

    Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Worldwide, gas hydrate is estimated to hold about 1016 kg of organic carbon in the form of methane (Kvenvolden et al., 1993). Gas hydrate is one of the fossil fuel resources that is yet untapped, but may play a major role in meeting the energy challenge of this century. In June 2002, Westport Technology Center was requested by the Department of Energy (DOE) to prepare a ''Best Practices Manual on Gas Hydrate Coring, Handling and Analysis'' under Award No. DE-FC26-02NT41327. The scope of the task was specifically targeted for coring sediments with hydrates in Alaska, the Gulf of Mexico (GOM) and from the present Ocean Drilling Program (ODP) drillship. The specific subjects under this scope were defined in 3 stages as follows: Stage 1: Collect information on coring sediments with hydrates, core handling, core preservation, sample transportation, analysis of the core, and long term preservation. Stage 2: Provide copies of the first draft to a list of experts and stakeholders designated by DOE. Stage 3: Produce a second draft of the manual with benefit of input from external review for delivery. The manual provides an overview of existing information available in the published literature and reports on coring, analysis, preservation and transport of gas hydrates for laboratory analysis as of June 2003. The manual was delivered as draft version 3 to the DOE Project Manager for distribution in July 2003. This Final Report is provided for records purposes.

  8. Recently Exposed Fumarole Fields Near Mullet Island, Imperial County, California

    Science.gov (United States)

    Lynch, D. K.; Hudnut, K.; Adams, P.; Bernstein, L.

    2011-12-01

    New field observations, lidar measurements, aerial imaging and preliminary laboratory measurements of mud samples are reported of three formerly submerged fumarole fields in the Salton Trough near Mullet Island in southeastern California, USA. The fumarole fields have recently been exposed as the Salton Sea level has dropped. The largest of the three fields visited in January 2011 is irregular in outline with a marked northeast elongation. It is roughly 400 meters long and 120 meters wide. The field consists of approximately one hundred warm to boiling hot (100° C) mud volcanoes (0.1 - 2 m in height), several hundred mud pots, and countless CO2 gas vents. Unusual shaped mud volcanoes in the form of vertical tubes with central vents were observed in many places. Lidar measurements were obtained in the time period Nov 9-13, 2010 using an Optech Orion 200M lidar from an elevation 800 m AGL. They reveal that the terrain immediately surrounding the two fields that are above water level reside on a low (~0.5 m high) gently sloping mound about 500 m across that shows no evidence of lineaments indicative of surface faulting. With other geothermal features, the fumaroles define a well-defined line marking the probable trace of the Calipatria fault. Although the precise locations is uncertain, it appears to define a straight line 4 km long between the Davis-Schrimpf mud volcanoes and Mullet Island. Mullet Island is one of five late Quaternary rhyolitic volcanic necks in the immediate area of the fumaroles. The Calipatria fault is subparallel to the San Andreas and Imperial faults and only one of many verified or suspected faults (including cross faults) in the complex tectonic setting of the Salton Trough. Mud from several volcanoes was analyzed using scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). One sample contained boussingaultite, (NH4)2Mg(SO4)2.6(H2O), a rare mineral that is known to sublime under fumarolic conditions, possibly by ammoniation of hydrated MgSO4. As the Salton Sea level continues to drop, the third fumarole field is expected to surface in the next couple of years. It is also likely that as more land emerges, many of the CO2 gas seeps currently under water will begin to for mud volcanoes and mud pots, most of them along the same NW trending axis as the others. At about the same time a land bridge will form to Mullet Island, the first in about 60 years.

  9. Trade in mineral resources

    OpenAIRE

    Davis, Graham A.

    2010-01-01

    This paper provides a review of current thinking on the economics of international trade in mineral resources. I first define what is meant by trade in mineral resources. I then discuss patterns of trade in mineral resources. The paper then moves on to the five topics requested by the World Trade Organization: theoretical and empirical literature on international trade in minerals; trade impacts of mineral abundance and the resource curse; the political economy of mineral trade in resource-ab...

  10. Association Between Crystalline Gray Hematite and Hydrated Units in Capri Chasma, Mars

    Science.gov (United States)

    Weitz, C. M.; Lane, M. D.; Noe Dobrea, E. Z.; Roach, L.; Knudson, A. T.

    2011-12-01

    We have mapped out the distribution, identified associated hydrated units, and proposed modes of formation for crystalline, gray hematite in Capri Chasma. HiRISE and CRISM images corresponding to the highest and largest abundances of gray hematite as measured by TES were analyzed for this study. Digital Terrain Models (DTMs) derived from HiRISE stereo pairs were used in a few locations to determine stratigraphic relationships between the hematite and other geologic units. In general, we find the gray hematite correlates to dark mantles situated on low-lying plains where there are nearby sulfate outcrops. A location with one of the highest abundances of hematite is situated on plains adjacent to kieserite outcrops. The dark hematite-bearing plains have spectra with a weak 1.93 ?m absorption and HiRISE images reveal small exposures of light-toned material beneath the hematite-bearing darker mantle. There are also several light-toned layered units with mineralogies that include opal, Fe/Mg-smectite, and an unidentified mineral exhibiting a 2.22/2.27 ?m doublet. These units are exposed within small hills located both inside and outside the hematite-bearing plains, and are unlikely to be the source of any hematite based upon their spatial distribution. Another location with a large occurrence of gray hematite is situated along the southern wall and floor of a ~30 km diameter, 2.5 km deep impact crater on the northern edge of the interior layered deposit within Capri Chasma. Multiple units are exposed along the crater wall, including a lower layered kieserite unit, followed by a layered mix of polyhydrated sulfates (PHS) and monohydrated sulfates, a layered PHS, a thick sequence of upper kieserite generally lacking layering, and finally an upper PHS. Covering many of these units are surficial mantles, including kiesereite-bearing dunes, spectrally bland eolian material, and a dark mantle with features centered at 1.05, 1.93, and 2.4 ?m, consistent with a mixture of hematite and PHS. The source of the crystalline hematite is likely grains that are weathering out of kieserite outcrops and collecting along the plains or lower slopes, presumably as soil lags. However, erosion of light-toned PHS material seen along portions of the chasma floor could also be the source of some hematite grains, particularly hematite locations that are several kms from the central interior layered deposit.

  11. A spectroscopic study of the mineral paceite (calcium acetate).

    Science.gov (United States)

    Musumeci, Anthony W; Frost, Ray L; Waclawik, Eric R

    2007-07-01

    A comprehensive spectroscopic analysis consisting of Raman, infrared (IR) and near-infrared (NIR) spectroscopy was undertaken on two forms of calcium acetate with differing degrees of hydration. Monohydrate (Ca(CH(3)COO)(2).H(2)O) and half-hydrate (Ca(CH(3)COO)(2).0.5H(2)O) species were analysed. Assignments of vibrational bands due to the acetate anion have been made in all three forms of spectroscopy. Thermal analysis of the mineral was undertaken to follow its decomposition under a nitrogen atmosphere. Three major mass loss steps at approximately 120, 400 and 600 degrees C were revealed. These mass losses correspond very well to firstly, the loss of co-ordinated water molecules, and then the loss of water from the acetate anion, followed by finally the loss of carbon dioxide from the carbonate mineral to form a stable calcium oxide. PMID:17070100

  12. Analysis of mixed-layer clay mineral structures

    Science.gov (United States)

    Bradley, W.F.

    1953-01-01

    Among the enormously abundant natural occurrences of clay minerals, many examples are encountered in which no single specific crystallization scheme extends through a single ultimate grain. The characterization of such assemblages becomes an analysis of the distribution of matter within such grains, rather than the simple identification of mineral species. It having become established that the particular coordination complex typified by mica is a common component of many natural subcrystalline assemblages, the opportunity is afforded to analyze scattering from random associations of these complexes with other structural units. Successful analyses have been made of mixed hydration states of montmorillonite, of montmorillonite with mica, of vermiculite with mica, and of montmorillonite with chlorite, all of which are variants of the mica complex, and of halloysite with hydrated halloysite.

  13. Clathrate hydrate tuning for technological purposes

    Science.gov (United States)

    di Profio, Pietro; Germani, Raimondo; Savelli, Gianfranco

    2010-05-01

    Gas hydrates are being increasingly considered as convenient media for gas storage and transportation as the knowledge of their properties increases, in particular as relates to methane and hydrogen. Clathrate hydrates may also represent a feasible sequestration technology for carbon dioxide, due to a well defined P/T range of stability, and several research programs are addressing this possibility. Though the understanding of the molecular structure and supramolecular interactions which are responsible of most properties of hydrates have been elucitated in recent years, the underlying theoretical physico-chemical framework is still poor, especially as relates to the role of "conditioners" (inhibitors and promoters) from the molecular/supramolecular point of view. In the present communication we show some results from our research approach which is mainly focused on the supramolecular properties of clathrate hydrate systems - and their conditioners - as a way to get access to a controlled modulation of the formation, dissociation and stabilization of gas hydrates. In particular, this communication will deal with: (a) a novel, compact apparatus for studying the main parameters of formation and dissociation of gas hydrates in a one-pot experiment, which can be easily and rapidly carried out on board of a drilling ship;[1] (b) the effects of amphiphile molecules (surfactants) as inhibitors or promoters of gas hydrate formation;[2] (c) a novel nanotechnology for a reliable and quick production of hydrogen hydrates, and its application to fuel cells;[3,4] and (d) the development of a clathrate hydrate tecnology for the sequestration and geological storage of man-made CO2, possibly with concomitant recovery of natural gas from NG hydrate fields. Furthermore, the feasibility of catalyzing the reduction of carbon dioxide to energy-rich species by hydrates is being investigated. [1] Di Profio, P., Germani, R., Savelli, G., International Patent Application PCT/IT2006/000274 [2] Di Profio P., Arca S., Germani R., Savelli G., 2005, "Surfactant promoting effects on clathrate hydrate formation: are micelles really involved?", Chem. Eng. Sci., 60, pp. 4141-4145 [3] Di Profio P., Arca S., Germani R., Savelli G., 2006, "Novel Nanostructured Media for Gas Storage and Transport: Clathrate Hydrates of Methane and Hydrogen", J. Fuel Cell Sci. & Tech., February 2007, vol. 4. [4] Di Profio, P., Germani, R., Savelli, G., EP07010346.

  14. Methane Recovery from Hydrate-bearing Sediments

    Energy Technology Data Exchange (ETDEWEB)

    J. Carlos Santamarina; Costas Tsouris

    2011-04-30

    Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. Methane hydrate can be an energy resource, contribute to global warming, or cause seafloor instability. This study placed emphasis on gas recovery from hydrate bearing sediments and related phenomena. The unique behavior of hydrate-bearing sediments required the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Therefore, the research methodology combined experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes. Research conducted as part of this project started with hydrate formation in sediment pores and extended to production methods and emergent phenomena. In particular, the scope of the work addressed: (1) hydrate formation and growth in pores, the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation; (2) the effect of physical properties such as gas solubility, salinity, pore size, and mixed gas conditions on hydrate formation and dissociation, and it implications such as oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations; (3) fluid conductivity in relation to pore size distribution and spatial correlation and the emergence of phenomena such as flow focusing; (4) mixed fluid flow, with special emphasis on differences between invading gas and nucleating gas, implications on relative gas conductivity for reservoir simulations, and gas recovery efficiency; (5) identification of advantages and limitations in different gas production strategies with emphasis; (6) detailed study of CH4-CO2 exchange as a unique alternative to recover CH4 gas while sequestering CO2; (7) the relevance of fines in otherwise clean sand sediments on gas recovery and related phenomena such as fines migration and clogging, vuggy structure formation, and gas-driven fracture formation during gas production by depressurization.

  15. 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 lower heat transfer rate in the internal heat exchanger than was designed. It is believed that the fins on the heat-exchanger tubes did not make proper contact with the tubes transporting the chilled glycol, and pairs of fins were too close for interior areas of fins to serve as hydrate collection sites. A correction of the fabrication fault in the heat exchanger fin attachments could be easily made to provide faster formation rates. The storage success with the POC process provides valuable information for making the process an economically viable process for safe, aboveground natural-gas storage.

  16. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    Science.gov (United States)

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  17. Clinker-mineral 2; Kurinka kobutsu 2

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Koichiro [Nagoya Institute of Technology, Nagoya (Japan)

    1998-09-10

    By using {gamma}-C{sub 2}G of which the hydration activity is very high with {gamma}-C{sub 2}G that that it is the material which the hydration activity is very low, as there is, is said and crystal structure equal to this chemical compound in the cementing conjunction thing as a contrast, Yamaguchi et al. was examined on the model which expresses the hydration from the DV-X{alpha} method. Amano et al. examined the effect of Mg0 of the minority on chemical composition and crystal structure of the each clinker mineral which was included in the clinker. It was reported that the lattice constant of constituent phase and alite and ferrite of the alite remarkably changed. It is anticipated that the cement raw material will mix metal and halogen in future. Migo noticed these from the viewpoint of the reuse of the earth resource. In a series of research, fluorine and chlorine were taken up as halogen. The effect of iron oxide in the generation of 12Cao, 7Al{sub 2}O{sub 3} solid solution including this was examined. Hakojima et al. discussed under 0.075 mm and clinker granulation mechanism of the 0.075{approx}1.2 mm diameter particle for the purpose of estimating the granulation process of the kiln inside from the clinker characteristics, from the viewpoint of chemical composition and clinker organization of every particle size of cyclone raw material. (translated by NEDO)

  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 processes that control production potential of hydrates in marine settings, Mallik was included because of the extensive data collected in a producible hydrate accumulation. To date, such a location had not been studied in the oceanic environment. The project worked closely with ongoing projects (e.g. GOM JIP and offshore India) that are actively investigating potentially economic hydrate accumulations in marine settings. The overall approach was fivefold: (1) collect key data concerning hydrocarbon fluxes which is currently missing at all locations to be included in the study, (2) use this and existing data to build numerical models that can explain gas hydrate variance at all four locations, (3) simulate how natural gas could be produced from each location with different production strategies, (4) collect new sediment property data at these locations that are required for constraining fluxes, production simulations and assessing sediment stability, and (5) develop a method for remotely quantifying heterogeneities in gas hydrate and free gas distributions. While we generally restricted our efforts to the locations where key parameters can be measured or constrained, our ultimate aim was to make our efforts universally applicable to any hydrate accumulation.

  19. Electrical properties of methane hydrate + sediment mixtures

    Science.gov (United States)

    Du Frane, Wyatt L.; Stern, Laura A.; Weitemeyer, Karen A.; Constable, Steven; Roberts, Jeffery J.

    2011-01-01

    As part of our DOE-funded proposal to characterize gas hydrate in the Gulf of Mexico using marine electromagnetic methods, a collaboration between SIO, LLNL, and USGS with the goal of measuring the electrical properties of lab-created methane (CH4) hydrate and sediment mixtures was formed. We examined samples with known characteristics to better relate electrical properties measured in the field to specific gas hydrate concentration and distribution patterns. Here we discuss first-ever electrical conductivity (?) measurements on unmixed CH4 hydrate (Du Frane et al., 2011): 6 x 10-5 S/m at 5 °C, which is ~5 orders of magnitude lower than seawater. This difference allows electromagnetic (EM) techniques to distinguish highly resistive gas hydrate deposits from conductive water saturated sediments in EM field surveys. More recently, we performed measurements on CH4 hydrate mixed with sediment and we also discuss those initial findings here. Our results on samples free of liquid water are important for predicting conductivity of sediments with pores highly saturated with gas hydrate, and are an essential starting point for comprehensive mixing models.

  20. 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.

  1. Minerals from Macedonia: XV. Sivec mineral assemble

    International Nuclear Information System (INIS)

    The paper presents investigations carried out on the collected minerals from the Sivec deposit. It is situated in the vicinity of the town of Prilep, representing a rare occurrence of sugary white dolomite marbles. The application of suitable methods of exploitation of decorative-dimension stones makes possible to obtain large amounts of commercial blocks well known in the world. Despite the existence of dolomite marbles, a series of exotic minerals are typical in Sivec mineralization. Among them, the most significant are: calcite, fluorite, rutile, phlogopite, corundum, diaspore, almandine, kosmatite (clintonite or margarite), clinochlore, muscovite, quartz, pyrite, tourmaline and zoisite. An attempt to identify ten collected minerals using the FT IR spectroscopy is performed. The identification of the minerals was based on the comparison of the infrared spectra of our specimens with the corresponding literature data for the mineral species originating all over the world. The coloured pictures of all studied silicate minerals are presented as well. (Author)

  2. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-03-01

    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 second year of a three-year endeavor being sponsored by Maurer Technology, Noble, and Anadarko Petroleum, in partnership with the DOE. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition. We plan to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. We also plan to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope is to drill and core a well on Anadarko leases in FY 2003 and 2004. We are also using an on-site core analysis laboratory to determine some of the physical characteristics of the hydrates and surrounding rock. The well is being drilled from a new Anadarko Arctic Platform that will have minimal footprint and environmental impact. We hope to correlate geology, geophysics, logs, and drilling and production data to allow reservoir models to be calibrated. Ultimately, our goal is to form an objective technical and economic evaluation of reservoir potential in Alaska.

  3. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-04-01

    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 much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  4. Carbon dioxide hydrate and floods on Mars

    Science.gov (United States)

    Milton, D. J.

    1974-01-01

    Ground ice on Mars probably consists largely of carbon dioxide hydrate. This hydrate dissociates upon release of pressure at temperatures between 0 and 10 C. The heat capacity of the ground would be sufficient to produce up to 4% (by volume) of water at a rate equal to that at which it can be drained away. Catastrophic dissociation of carbon dioxide hydrate during some past epoch when the near-surface temperature was in this range would have produced chaotic terrain and flood channels.

  5. On the electrolytic generation of hydrated electron

    International Nuclear Information System (INIS)

    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 O2 yielding the transient O2- 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)

  6. 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.

  7. SOME STRUCTURAL STUDIES OF CLATHRATE HYDRATES

    OpenAIRE

    Davidson, D.; Gough, S.; Handa, Y.; Ratcliffe, C.; Ripmeester, J.; Tse, J.

    1987-01-01

    We have prepared the hydrates of oxygen, nitrogen, carbon monoxide and air in their regions of stability at high pressure. Except for carbon monoxide hydrate, whose structure is not yet confirmed, the X-ray and/or neutron powder diffraction patterns show their structures to be von Stackelberg's type II. Clathrate hydrates of methylcyclohexane, pinacolone and t-butyl methyl ether with H2S or Xe as help gas, were identified from the 2H NMR spectra of deuterated or partially deuterated guest mol...

  8. Clathrate hydrates in cometary nuclei and porosity

    Science.gov (United States)

    Smoluchowski, R.

    1988-01-01

    Possible mechanisms of formation and decomposition of CO2-clathrate hydrate in cometary nuclei are discussed. As far as it is known, this is the only clathrate hydrate which is unstable at low temperatures. Calculation shows that, in accord with other evidence, neither volume nor grain boundary diffusion in the clathrate lattice can be responsible for the rate of these reactions and that a surface mechanism with the attendant sensitivity to pressure must play a crucial role. Density changes accompanying CO2-clathrate decomposition and formation can lead to microporosity and enhanced brittleness or even to fracture of cometary nuclei at low temperatures. Other clathrate hydrates and mixed clathrates are also discussed.

  9. Calcium-aluminum-silicate-hydrate "cement" phases and rare Ca-zeolite association at Colle Fabbri, Central Italy

    Science.gov (United States)

    Stoppa, F.; Scordari, F.; Mesto, E.; Sharygin, V.; Bortolozzi, G.

    2010-06-01

    Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) — "cement" phases - i.e., thaumasite, strätlingite and an ettringite-like phase and several different species of zeolites: chabazite-Ca, willhendersonite, gismon-dine, three phases bearing Ca with the same or perhaps lower symmetry of phillipsite-Ca, levyne-Ca and the Ca-rich analogue of merlinoite. In addition, apophyllite-(KF) and/or apophyllite-(KOH), Ca-Ba-carbonates, portlandite and sulphates were present. A new polymorph from the pyrrhotite group, containing three layers of sphalerite-type structure in the unit cell, is reported for the first time. Such a complex association is unique. Most of these minerals are specifically related to hydration processes of: (1) pyrometamorphic metacarbonate/metapelitic rocks (natural analogues of cement clinkers); (2) mineralization between intrusive stocks and slates; and (3) high-calcium, alkaline igneous rocks such as melilitites and foidites as well as carbonatites. The Colle Fabbri outcrop offers an opportunity to study in situ complex crystalline overgrowth and specific crystal chemistry in mineral phases formed in igneous to hydrothermal conditions.

  10. Modeling Natural Gas Productivity Recovery from a Hydrate Reservoir Well

    Directory of Open Access Journals (Sweden)

    Bin Dou

    2013-04-01

    Full Text Available The hydrocarbon deposits have stimulated worldwide efforts to understand gas production from hydrate dissociation in hydrate reservoirs well. This paper deals with the potential of gas hydrates as a source of energy which is widely available in permafrost and oceanic sediments. It discusses methods for gas production from natural gas hydrates. Authors provide a detailed methodology used to model gas productivity recovery from hydrate reservoir well. The mathematical modelling of gas dissociation from hydrate reservoir as a tool for evaluating the potential of gas hydrates for natural gas production. The simulation results show that the process of natural gas production in a hydrate reservoir is a sensitive function of reservoir temperature and hydrate zone permeability. The model couples nth order decomposition kinetics with gas flow through porous media. The models provide a simple and useful tool for hydrate reservoir analysis.

  11. Theoretical temperature dependency of gas hydrate former solubility under hydrate-liquid water equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    Bergeron, Sebastien [Department of Chemical Engineering, McGill University, Montreal, Que., H3A 2B2 (Canada); Macchi, Arturo [Department of Chemical Engineering, University of Ottawa (Canada); Servio, Phillip [Department of Chemical Engineering, McGill University, Montreal, Que., H3A 2B2 (Canada)]. E-mail: phillip.servio@mcgill.ca

    2007-05-15

    Available experimental data and current semi-empirical models suggest a positive trend for the gas hydrate former solubility in the bulk liquid phase as a function of temperature under hydrate-liquid water equilibrium. Such a trend has been widely reported without theoretical explanation. This work proposes a comprehensive derivation, based on fundamental thermodynamics, of the gas hydrate former solubility dependency on temperature for any binary system under two-phase equilibrium.

  12. Theoretical temperature dependency of gas hydrate former solubility under hydrate-liquid water equilibrium

    International Nuclear Information System (INIS)

    Available experimental data and current semi-empirical models suggest a positive trend for the gas hydrate former solubility in the bulk liquid phase as a function of temperature under hydrate-liquid water equilibrium. Such a trend has been widely reported without theoretical explanation. This work proposes a comprehensive derivation, based on fundamental thermodynamics, of the gas hydrate former solubility dependency on temperature for any binary system under two-phase equilibrium

  13. Individual and combined effects of chloride, sulfate, and magnesium ions on hydrated Portland-cement paste

    International Nuclear Information System (INIS)

    Ground water with a high concentration of magnesium ion is known to cause deterioration to portland cement concretes. A proposed mechanism for this deterioration process published previously involves an approximate 1:1 replacement of Ca ions by Mg ions in the crystalline phases of hydrated cement. The current study was undertaken to determine which ions, among magnesium, chloride, and sulfate, cause deterioration; whether their deleterious action is individual or interdependent; and to relate this mechanism of deterioration to the outlook for a 100-yr service life of concretes used in mass placements at the Waste Isolation Pilot Plant. Loss of Ca ion by cement pastes was found to be strongly related to the concentration of Mg ion in simulated ground-water solutions in which the paste samples were aged. This was true of both salt- containing and conventional cement pastes. No other ion in the solutions exerted a strong effect on Ca loss. Ca ion left first from calcium hydroxide in the pastes, depleting all calcium hydroxide by 60 days. Some calcium silicate hydrate remained even after 90 days in the solutions with the highest concentration of Mg ion, while the paste samples deteriorated noticeably. The results indicated a mechanism that involves dissolution of Ca phases and transport of Ca ions to the surface of the sample, followed by formation of Mg-bearing phases at this reaction surface rather than directly by substitution within the microstructure of hydrated cement. Given that calcium hydroxide and calcium silicate hydrate are the principal strength-giving phases of hydrated cement, this mechanism indicates the likelihood of significant loss of integrity of a concrete exposed to Mg-bearing ground water at the WIPP. The rate of deterioration ultimately will depend on Mg-ion concentration, the microstructure materials of the concrete exposed to that groundwater, and the availability of brine

  14. Aluminium phosphate sulphate minerals (APS) associated with proterozoic unconformity-type uranium deposits: crystal-chemical characterisation and petrogenetic significance; Les sulfates phosphates d'aluminium hydrates (APS) dans l'environnement des gisements d'uranium associes a une discordance proterozoique: caracterisation cristallochimique et signification petrogenetique

    Energy Technology Data Exchange (ETDEWEB)

    Gaboreau, St

    2005-07-01

    Aluminium phosphate sulfate minerals (APS) are particularly widespread and spatially associated with hydrothermal clay alteration in both the East Alligator River Uranium Field (Northern Territory, Australia) and the Athabasca basin (Saskatchewan, Canada), in the environment of proterozoic unconformity-related uranium deposits (URUD). The purpose of this study is both: 1) to characterize the nature and the origin of the APS minerals on both sides of the middle proterozoic unconformity between the overlying sandstones and the underlying metamorphic basement rocks that host the uranium ore bodies, 2) to improve our knowledge on the suitability of these minerals to indicate the paleo-conditions (redox, pH) at which the alteration processes relative to the uranium deposition operated. The APS minerals result from the interaction of oxidising and relatively acidic fluids with aluminous host rocks enriched in monazite. Several APS-bearing clay assemblages and APS crystal-chemistry have also been distinguished as a function of the distance from the uranium ore bodies or from the structural discontinuities which drained the hydrothermal solutions during the mineralisation event. One of the main results of this study is that the index mineral assemblages, used in the recent literature to describe the alteration zones around the uranium ore bodies, can be theoretically predicted by a set of thermodynamic calculations which simulate different steps of fluid-rock interaction processes related to a downward penetrating of hyper-saline, oxidizing and acidic diagenetic fluids through the lower sandstone units of the basins and then into the metamorphic basement rocks. The above considerations and the fact that APS with different crystal-chemical compositions crystallized in a range of fO{sub 2} and pH at which uranium can either be transported in solution or precipitated as uraninite in the host-rocks make these minerals not only good markers of the degree of alteration of the basement rocks but also very good indicators of the fO{sub 2} and pH paleo-conditions at which the formation of the U-ore bodies took place. (author)

  15. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

  16. Modeling Natural Gas Productivity Recovery from a Hydrate Reservoir Well

    OpenAIRE

    Bin Dou; Hui Gao; Binbin Fan; Lei Ren

    2013-01-01

    The hydrocarbon deposits have stimulated worldwide efforts to understand gas production from hydrate dissociation in hydrate reservoirs well. This paper deals with the potential of gas hydrates as a source of energy which is widely available in permafrost and oceanic sediments. It discusses methods for gas production from natural gas hydrates. Authors provide a detailed methodology used to model gas productivity recovery from hydrate reservoir well. The mathematical modelling of gas dissocia...

  17. Physical properties of sediment containing methane gas hydrate

    Science.gov (United States)

    Winters, W.J.; Waite, W.F.; Mason, D.H.; Gilbert, L.Y.

    2005-01-01

    A study conducted by the US Geological Survey (USGS) on the formation, behavior, and properties of mixtures of gas hydrate and sediment is presented. The results show that the properties of host material influence the type and quantity of hydrates formed. The presence of hydrate during mechanical shear tests affects the measured sediment pore pressure. Sediment shear strength may be increased more than 500 percent by intact hydrate, but greatly weakened if the hydrate dissociates.

  18. X-ray diffraction modelling technique as a tool to investigate smectite structural changes through its hydration properties

    International Nuclear Information System (INIS)

    Its very low permeability after compaction and its cation retention ability make bentonite a possible buffer material in the multi-barrier concepts developed for nuclear waste repositories. The above properties of bentonite are mainly influenced by its smectite component as a result of the specific hydration/expansion ability and cation exchange capacity of this mineral. However, interactions between the waste package and the clay barrier could possibly alter significantly these properties. For example and by analogy with burial diagenesis, smectite can be expected to transform into the non-expandable mineral illite through intermediate mixed-layer structures as a result of the thermal pulse induced by the waste intrinsic activity. During the early stages of this transformation, structural changes reported in the literature affect essentially the location and the amount of smectite charge. Because these differences most likely result in subtle changes of smectite hydration properties, a careful study of these properties using X-ray diffraction (XRD ) is possibly a way to investigate the early steps of the smectite-to-illite transition. Smectite typically shows a stepwise hydration behaviour corresponding to the intercalation of 0, 1 or 2 discrete sheets of water molecules in its interlayers. However, heterogeneities of charge location (between octahedral and tetrahedral sheets) and/or of charge amount (from one interlayer to the other or within a given interlayer) moshe other or within a given interlayer) most often lead to the coexistence of different hydration states within smectite crystals. These heterogeneities in hydration state are best revealed by comparing experimental X-ray diffraction (XRD) patterns to calculated profiles using a trial-and-error procedure. For natural reference smectites, the developed XRD profile modelling approach allows the description of hydration heterogeneities and of hydration state evolution as a function of RH conditions, layer charge and charge location. The structure models show that, for the SWy-1 reference low-charge montmorillonite, the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. Following a water desorption isotherm, the transition between the different hydration states is shifted towards lower RH values with increasing the layer charge. In addition, the hydration of beidellite samples (tetrahedral charge) is shown to be more heterogeneous than that of montmorillonite. The approach developed should thus allow describing the structural modifications reported during the early stages of the smectite-to-illite transition. In addition, the developed methodology can be used to describe the changes in hydration sate evolution resulting from the modification of the interlayer composition. For example, under strongly acidic conditions the Ca2+ - H+ exchange modifies the hydration state of smectite, which is bi-hydrated when Ca-saturated and mono-hydrated when H+-exchanged. Results show that individual smectite interlayers are either H+ or Ca2+ saturated and that the two species do not coexist in the same interlayer and the mechanism of Ca2+ to H+ exchange can be determined by combining results from XRD profile modelling and chemical modelling

  19. X-ray diffraction modelling technique as a tool to investigate smectite structural changes through its hydration properties

    Energy Technology Data Exchange (ETDEWEB)

    Ferrage, E.; Lanson, B. [Universite Joseph Fourier- CNRS, Environmental Geochemistry Group, LGIT - Maison des Geosciences, 38 - Grenoble, (France); Ferrage, E.; Jacquot, E. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2005-07-01

    Its very low permeability after compaction and its cation retention ability make bentonite a possible buffer material in the multi-barrier concepts developed for nuclear waste repositories. The above properties of bentonite are mainly influenced by its smectite component as a result of the specific hydration/expansion ability and cation exchange capacity of this mineral. However, interactions between the waste package and the clay barrier could possibly alter significantly these properties. For example and by analogy with burial diagenesis, smectite can be expected to transform into the non-expandable mineral illite through intermediate mixed-layer structures as a result of the thermal pulse induced by the waste intrinsic activity. During the early stages of this transformation, structural changes reported in the literature affect essentially the location and the amount of smectite charge. Because these differences most likely result in subtle changes of smectite hydration properties, a careful study of these properties using X-ray diffraction (XRD ) is possibly a way to investigate the early steps of the smectite-to-illite transition. Smectite typically shows a stepwise hydration behaviour corresponding to the intercalation of 0, 1 or 2 discrete sheets of water molecules in its interlayers. However, heterogeneities of charge location (between octahedral and tetrahedral sheets) and/or of charge amount (from one interlayer to the other or within a given interlayer) most often lead to the coexistence of different hydration states within smectite crystals. These heterogeneities in hydration state are best revealed by comparing experimental X-ray diffraction (XRD) patterns to calculated profiles using a trial-and-error procedure. For natural reference smectites, the developed XRD profile modelling approach allows the description of hydration heterogeneities and of hydration state evolution as a function of RH conditions, layer charge and charge location. The structure models show that, for the SWy-1 reference low-charge montmorillonite, the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. Following a water desorption isotherm, the transition between the different hydration states is shifted towards lower RH values with increasing the layer charge. In addition, the hydration of beidellite samples (tetrahedral charge) is shown to be more heterogeneous than that of montmorillonite. The approach developed should thus allow describing the structural modifications reported during the early stages of the smectite-to-illite transition. In addition, the developed methodology can be used to describe the changes in hydration sate evolution resulting from the modification of the interlayer composition. For example, under strongly acidic conditions the Ca{sup 2+} - H{sup +} exchange modifies the hydration state of smectite, which is bi-hydrated when Ca-saturated and mono-hydrated when H{sup +}-exchanged. Results show that individual smectite interlayers are either H{sup +} or Ca{sup 2+} saturated and that the two species do not coexist in the same interlayer and the mechanism of Ca{sup 2+} to H{sup +} exchange can be determined by combining results from XRD profile modelling and chemical modelling.

  20. A pump-probe XFEL particle injector for hydrated samples

    CERN Document Server

    Weierstall, U; Spence, J C H

    2011-01-01

    We have developed a liquid jet injector system that can be used for hydrated sample delivery at X-ray Free Electron Laser (XFEL) sources and 3rd generation synchrotron sources. The injector is based on the Gas Dynamic Virtual Nozzle (GDVN), which generates a liquid jet with diameter ranging from 300 nm to 20 {\\mu}m without the clogging problems associated with conventional Rayleigh jets. An improved nozzle design is presented here. A differential pumping system protects the vacuum chamber and an in-vacuum microscope allows observation of the liquid jet for diagnostics while it is being exposed to the X-ray beam. A fiber optically coupled pump laser illuminating the jet is incorporated for pump-probe experiments. First results with this injector system have been obtained at the LCLS.

  1. Gas hydrate equilibrium dissociation conditions in porous media using two thermodynamic approaches

    International Nuclear Information System (INIS)

    We employ two thermodynamic approaches, based on the equal fugacities and the equal activities, to predict the gas hydrate equilibrium dissociation conditions in the porous media. The predictions are made for the hydrate systems, CH4/H2O, C2H6/H2O, C3H8/H2O, CO2/H2O, CH4/CO2/H2O, C3H8/CH4/C2H6/H2O, and CH4/CH3OH/H2O. For the non-hydrate phase, we used the Trebble-Bishnoi equation in the fugacity approach and the Soave-Redlich-Kwong equation in the activity approach. For the hydrate phase, the van der Waals-Platteeuw model incorporated with the capillary model of Llamedo et al. [M. Llamedo, R. Anderson, B. Tohidi, Am. Mineral. 89 (2004) 1264-1270] was used in the two approaches. The predictions are found to be in satisfactory to good agreement with the experimental data. The predictive ability of the fugacity approach is better than that of the activity approach

  2. Gas hydrate equilibrium dissociation conditions in porous media using two thermodynamic approaches

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaosen [Guangzhou Institute of Energy Conversion and Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou 510640 (China)], E-mail: lixs@ms.giec.ac.cn; Zhang Yu; Li Gang; Chen Zhaoyang; Yan Kefeng [Guangzhou Institute of Energy Conversion and Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou 510640 (China); Li Qingping [Deepwater Engineering Key Laboratory, Technology Research Department, CNOOC Research Center, Beijing 100027 (China)

    2008-09-15

    We employ two thermodynamic approaches, based on the equal fugacities and the equal activities, to predict the gas hydrate equilibrium dissociation conditions in the porous media. The predictions are made for the hydrate systems, CH{sub 4}/H{sub 2}O, C{sub 2}H{sub 6}/H{sub 2}O, C{sub 3}H{sub 8}/H{sub 2}O, CO{sub 2}/H{sub 2}O, CH{sub 4}/CO{sub 2}/H{sub 2}O, C{sub 3}H{sub 8}/CH{sub 4}/C{sub 2}H{sub 6}/H{sub 2}O, and CH{sub 4}/CH{sub 3}OH/H{sub 2}O. For the non-hydrate phase, we used the Trebble-Bishnoi equation in the fugacity approach and the Soave-Redlich-Kwong equation in the activity approach. For the hydrate phase, the van der Waals-Platteeuw model incorporated with the capillary model of Llamedo et al. [M. Llamedo, R. Anderson, B. Tohidi, Am. Mineral. 89 (2004) 1264-1270] was used in the two approaches. The predictions are found to be in satisfactory to good agreement with the experimental data. The predictive ability of the fugacity approach is better than that of the activity approach.

  3. Natural gas hydrates: myths, facts and issues; Hydrates de gaz naturels: mythes realite et enjeux

    Energy Technology Data Exchange (ETDEWEB)

    Beauchamp, B. [Geological Survey (Canada)

    2004-07-01

    Gas hydrates are solid-like substances naturally occurring beneath the oceans and in polar regions. They contain vast, and potentially unstable, reserves of methane and other natural gases. Many believe that, if released in the environment, the methane from hydrates would be a considerable hazard to marine ecosystems, coastal populations and infrastructures, or worse, that it would dangerously contribute to global warming. On the other hand, hydrates may contain enough natural gas to provide an energy supply assurance for the 21. century. This paper attempts to separate the myths, the facts and the issues that relate to natural gas hydrates beyond the doomsday environmental scenarios and overly optimistic estimates. (author)

  4. Methane hydrate resource assessment of the outer continental shelf : in-place Gulf of Mexico results

    Energy Technology Data Exchange (ETDEWEB)

    Frye, M. [Minerals Mangement Service, Herndon, VA (United States); Grace, J. [Earth Science Associates, Long Beach, CA (United States); Hunt, J.; Shedd, W. [Minerals Management Service, New Orleans, LA (United States); Kaufman, G. [Massachusetts Inst. of Technology, Boston, MA (United States); Schuenemeyer, J. [Southwest Statistical Consulting, Cortez, CO (United States)

    2008-07-01

    The Minerals Management Service (MMS) is division of the United States (U.S.) Department of the Interior. Its mandate is to manage natural gas, oil, and other mineral resources on the U.S. outer continental shelf (OCS). The MMS launched a project in order to provide an assessment of the natural gas hydrate resource potential across the entire OCS, including the Alaskan, Atlantic, Gulf of Mexico, and Pacific margins. The purpose of this ongoing project is to provide a probabilistic evaluation of in-place, technically recoverable, and economically recoverable gas hydrate resources. This paper provided an overview of the project, including a preliminary assessment of in-place gas hydrate resources in the Gulf of Mexico. The paper described the probabilistic model that was built on a mass balance approach to assessment. The model provided a high degree of spatial resolution and supported detailed mapping. The model produced a Monte Carlo distribution of in-place resources that ranged from 314 trillion to 974 trillion cubic meters (TCM) with a mean value of 607 TCM. The paper also provided a link to the full report which included the model methodology, underlying assumptions, and input datasets. Additional work on the development of a technically recoverable model component is currently underway. 1 fig.

  5. 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.

  6. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Thomas Williams; Bjorn Paulsson; Alexander Goertz

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a drilling hazard by the oil and gas industry for years. Drilling engineers working in Russia, Canada and the USA have documented numerous problems, including drilling 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 as a potential energy source agree that the resource potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained from physical samples taken from actual hydrate-bearing rocks. 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 identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The project team drilled and continuously cored the Hot Ice No. 1 well on Anadarko-leased acreage beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and used for determining physical characteristics of hydrates and surrounding rock. After the well was logged, a 3D vertical seismic profile (VSP) was recorded to calibrate the shallow geologic section with seismic data and to investigate techniques to better resolve lateral subsurface variations of potential hydrate-bearing strata. Paulsson Geophysical Services, Inc. deployed their 80 level 3C clamped borehole seismic receiver array in the wellbore to record samples every 25 ft. Seismic vibrators were successively positioned at 1185 different surface positions in a circular pattern around the wellbore. This technique generated a 3D image of the subsurface. Correlations were generated of these seismic data with cores, logging, and other well data. Unfortunately, the Hot Ice No. 1 well did not encounter hydrates in the reservoir sands, although brine-saturated sands containing minor amounts of methane were encountered within the hydrate stability zone (HSZ). Synthetic seismograms created from well log data were in agreement with reflectivity data measured by the 3D VSP survey. Modeled synthetic seismograms indicated a detectable seismic response would be expected in the presence of hydrate-bearing sands. Such a response was detected in the 3D VSP data at locations up-dip to the west of the Hot Ice No. 1 wellbore. Results of this project suggest that the presence of hydrate-bearing strata may not be related as simply to HSZ thickness as previously thought. Geological complications of reservoir facies distribution within fluvial-deltaic environments will require sophisticated detection technologies to assess the locations of recoverable volumes of methane contained in hydrates. High-resolution surface seismic data and more rigorous well log data analysis offer the best near-term potential. The hydrate resource potential is huge, but better tools are needed to accurately assess their location, distribution and economic recoverability.

  7. 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

  8. HYDRATION AND ACETYLATION OF LIMONENE: SUPPORTED HETEROPOLYACIDS

    Scientific Electronic Library Online (English)

    MARIA CECILIA, AVILA; NORA A, COMELLI; NORBERTO H, FIRPO; ESTHER N, PONZI; MARTA I, PONZI.

    1449-14-01

    Full Text Available SciELO Chile | Language: English Abstract in english The limonene hydration and acetylation in liquid phase catalyzed by phosphotungstic and phosphomolybdic acid bulk and supported on silica and titanium dioxide were studied. The reaction was performed in a batch reactor in acetic acid at 40°C, with magnetic stirring of the reaction mixture. Reaction [...] products were analyzed by gaseous chromatography with FID detector using a capillary column for separation of products. The identification of compounds was made with pattern terpenes and by gaseous chromatography with mass spectrometry. All catalysts tested result to be active in the hydration and acetylation reaction of limonene. Catalysts based on phophotungstic acid (HPW) produce larger amount of hydration and acetylation products than phosphomolybdic acid (HPMo) catalyst. Hydration products increase faster than isomerization products when the reaction time is increased. The structure of heteropolyacids and the presence of acid sites Bronsted and Lewis were determined by FTIR

  9. Towards Commercial Gas Production from Hydrate Deposits

    Directory of Open Access Journals (Sweden)

    Richard Dawe

    2011-01-01

    Full Text Available Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. The general consensus is that there are vast quantities of natural gas trapped in hydrate deposits in geological systems, and this has resulted in the emerging importance of hydrates as a potential energy resource and an accompanying proliferation of recent studies on the technical and economic feasibility of gas production from hydrates. There are then the associated environmental concerns. This study reviews the state of knowledge with respect to natural gas hydrates and outlines remaining challenges and knowledge gaps.

  10. Neutron cross section of methane hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Kiyanagi, Y.; Date, S.; Horikawa, T.; Takamine, J.; Iwasa, H.; Kamiyama, T. [Graduate School of Eng., Hokkaido Univ., Sapporo (Japan); Uchida, T.; Ebinuma, T.; Narrita, H. [National Inst. of Advanced Industrial Science, Tsukisamu, Sapporo (Japan); Bennington, S.M. [ISIS Dept., Rutherford Appleton, Chilton, Didcot, Oxon (United Kingdom)

    2004-03-01

    To estimate the neutronic characteristics of methane hydrate and also to synthesize cross section data for simulation we need neutron scattering data ranging wide energy and momentum region. We performed inelastic neutron scattering experiments to get information about the neutron cross section on methane hydrate. It was found that at high momentum transfer region rotational mode as well as vibration mode showed recoil like behavior. On the other hand, at low momentum region, as well known, free rotation like energy levels were observed. The energy level of ice in methane hydrate was very similar to normal ice. The results suggest that the rough expression of the cross section of the methane hydrate is presented by linear combination of the methane and ice. (orig.)

  11. Oceanic hydrates: more questions than answers

    International Nuclear Information System (INIS)

    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

  12. Spectroscopic methods in gas hydrate research.

    Science.gov (United States)

    Rauh, Florian; Mizaikoff, Boris

    2012-01-01

    Gas hydrates are crystalline structures comprising a guest molecule surrounded by a water cage, and are particularly relevant due to their natural occurrence in the deep sea and in permafrost areas. Low molecular weight molecules such as methane and carbon dioxide can be sequestered into that cage at suitable temperatures and pressures, facilitating the transition to the solid phase. While the composition and structure of gas hydrates appear to be well understood, their formation and dissociation mechanisms, along with the dynamics and kinetics associated with those processes, remain ambiguous. In order to take advantage of gas hydrates as an energy resource (e.g., methane hydrate), as a sequestration matrix in (for example) CO(2) storage, or for chemical energy conservation/storage, a more detailed molecular level understanding of their formation and dissociation processes, as well as the chemical, physical, and biological parameters that affect these processes, is required. Spectroscopic techniques appear to be most suitable for analyzing the structures of gas hydrates (sometimes in situ), thus providing access to such information across the electromagnetic spectrum. A variety of spectroscopic methods are currently used in gas hydrate research to determine the composition, structure, cage occupancy, guest molecule position, and binding/formation/dissociation mechanisms of the hydrate. To date, the most commonly applied techniques are Raman spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Diffraction methods such as neutron and X-ray diffraction are used to determine gas hydrate structures, and to study lattice expansions. Furthermore, UV-vis spectroscopic techniques and scanning electron microscopy (SEM) have assisted in structural studies of gas hydrates. Most recently, waveguide-coupled mid-infrared spectroscopy in the 3-20 ?m spectral range has demonstrated its value for in situ studies on the formation and dissociation of gas hydrates. This comprehensive review summarizes the importance of spectroscopic analytical techniques to our understanding of the structure and dynamics of gas hydrate systems, and highlights selected examples that illustrate the utility of these individual methods. PMID:22094590

  13. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    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 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 a well (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 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. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in the project reports. Documenting the results of this effort are key to extracting lessons learned and maximizing the industry's benefits for future hydrate exploitation.

  14. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Steve Runyon; Mike Globe; Kent Newsham; 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. 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 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 planning hydrate exploration and development projects. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this and other project reports. This Topical Report contains details describing logging operations.

  15. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2004-11-01

    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 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 a well (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 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. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in the project reports. Documenting the results of this effort are key to extracting lessons learned and maximizing the industry's benefits for future hydrate exploitation. In addition to the Final Report, several companion Topical Reports are being published.

  16. Experimental investigation of smectite hydration from the simulation of 001 X-ray diffraction lines. Implications for the characterization of mineralogical modifications of the 'argilite' from the Meuse - Haute Marne site as a result of a thermal perturbation; Etude experimentale de l'hydratation des smectites par simulation des raies OOl de diffraction des rayons X. Implications pour l'etude d'une perturbation thermique sur la mineralogie de l'argilite du site Meuse-Haute Marne

    Energy Technology Data Exchange (ETDEWEB)

    Ferrage, E

    2004-10-15

    The structural modifications affecting the reactive mineral constituents of the clay barriers (smectite) and possibly resulting from the thermal pulse related to nuclear waste storage are essentially limited to the amount and location of the layer charge deficit. These modifications likely impact the hydration properties of these minerals, and a specific methodology has thus been developed to describe, using simulation of X-ray diffraction profiles (001 reflections), these hydration properties and specifically the heterogeneity resulting from the inter-stratification of different layer types, each exhibiting a specific hydration state. The detailed study of the hydration properties of a low-charge montmorillonite (octahedral charge) has shown that the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. If the layer charge is increased, the transition between the different hydration states is shifted, following a water desorption isotherm, towards lower relative humidities. In addition, the hydration of studied beidellites (tetrahedral charge) was shown to be more heterogeneous than that of montmorillonites. The developed methodology also allowed describing the structural modifications resulting from a chemical perturbation (chlorinated anionic background, pH). Finally, the link between the thickness of elementary layers and the amount of interlayer water molecules has been evidenced. A new structure model has also been determined for these interlayer species allowing an improved description of their positional distribution in bi-hydrated interlayers. (author)

  17. CO2 capture by gas hydrate crystallization

    OpenAIRE

    Fezoua, Amara; Bouchemoua-benaissa, Amina; Ouabbas, Yamina; Chauvy, Fabien; Cameira?o, Ana; Herri, Jean-michel

    2009-01-01

    Gas hydrates are formed at low temperature and high pressure. They are crystalline solid formed from mixtures of liquid water and low molecular weight gases. The water molecules that form the lattice are strongly hydrogen bonded and form a network of cavities in which the gas can be encaged. The gas molecules interact with the water molecules through van der Waals type dispersion forces, in a way which is similar to Langmuir absorption. Hydrate occurrence is a problem of flow assurance for de...

  18. Concentration dependence of ionic hydration numbers.

    Science.gov (United States)

    Marcus, Yizhak

    2014-09-01

    Isothermal compressibility data of 23 aqueous electrolyte solutions at 25 °C from the literature are used to calculate their hydration numbers, which diminish as the concentration increases. Their limit at very high concentration is near the "number of adsorption sites" of water molecules on the ions, obtained by the BET method. On the contrary, hydration numbers obtained from ultrasound speed measurements yielding isentropic compressibilities cannot be valid, being much too large at infinite dilution. PMID:25121925

  19. Influence of polysaccharides on cement hydration

    OpenAIRE

    Peschard, Arnaud; Govin, Alexandre; Fredon, Emmanuel; Grosseau, Philippe; Fantozzi, Gilles

    2004-01-01

    This paper is about the influence of polysaccharides on cement hydration. Three polysaccharides were studied: a cellulose ether (CE), a starch ether (SE) and a dextrin (YD). In a concentrated media as well as in a dilute media, admixture CE only revealed a slight effect on cement hydration. Portlandite and ettringite formation and gypsum consumption were slowed down by SE adjunction. Admixture YD induced an acceleration of ettringite formation as well as gypsum consumption whereas portiandite...

  20. Towards Commercial Gas Production from Hydrate Deposits

    OpenAIRE

    Richard Dawe; Jill Marcelle-De Silva

    2011-01-01

    Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. The general consensus is that there are vast quantities of natural gas trapped in hydrate deposits in geological systems, and this has resulted in the emerging importance of hydrates as a potential ...

  1. Carbon dioxide hydrates crystallisation in emulsion

    OpenAIRE

    Galfre?, Aure?lie; Fezoua, Amara; Ouabbas, Yamina; Cameira?o, Ana; Herri, Jean-michel

    2011-01-01

    Greenhouse gases emissions, like carbon dioxide, have been identified as major sources responsible for global warming. To reduce carbon dioxide emissions, capture process can be envisaged to extract CO2 from flue gases. In this work, the technology of CO2 separation and capture by gas hydrates crystallization is investigated. The principal barriers in developing this process are the necessary high conditions of formation (P, T), low hydrates formation rate, and separation efficiency. A promot...

  2. Comparative mineralogy in the Solar system: Water-related minerals and habitability

    Science.gov (United States)

    Prieto-Ballesteros, O.; Muñoz-Iglesias, V.; Bonales, L. J.

    2012-09-01

    Life, as we know it, needs liquid water because its unique physical chemical properties. The presence of liquid water in a planetary environment anytime during its geological history may be evidenced studying the present mineralogy. While some minerals incorporate water molecules directly in their structure when crystallize from liquid, some anhydrous need the aqueous environment to be formed primarily or by alteration. Salt hydrates (sulfates, chlorides), clathrate hydrates, hydrated silicates (clays, zeolites) and oxides are some examples of these minerals conspicuous for their interest on Astrobiology. Here we support waterrelated minerals as indicators of planetary habitability and revise their occurrence in the solar system. Investigations of terrestrial analogue materials, both in the laboratory and in situ are needed in order to interpret the data from the space missions properly. Phase stability and physical chemical properties data of the minerals are being obtained and used to infer specific characteristics of the past and the present of potential habitable environments. Water-related minerals have been observed at different solar system objects such as: a) meteorites [1] and asteroids [2]. b) the surface of terrestrial planets like Mars [3, 4, 5]. c) some icy satellites [6, 7, 8, 9]. a) The hydrated mineral inventory in meteorites and asteroid helps to both, infer the origin of Earth's water, and decode the water/organic processes interaction occurring during the earliest times in solar system history. b) Main climatic and geological global changes of Mars have been established by some authors [3] from the abundance of some hydrated species as sulfates or clays. Some detected sulfates, like the jarosite has been used even to indicate the extreme acidity of the aqueous environment from where they were precipitated. Studies on terrestrial extreme environments have shown that if hydrothermal samples are present on Mars, like carbonates, they might be useful as indicators of past life or habitability. c) Hydrated salts are particularly important in icy satellites. It has been proposed that the origin of the hydrated sulfur-bearing species observed at the surfaces of Europa or Ganymede is their putative internal oceans. These salts would be the responsible for the induced magnetic fields of both satellites. They may incorporate the essential elements for Life, and preserve biosignatures in their layers. They crystallize at deep aqueous environments under pressure, conditions different from the typical evaporites at the surface of the terrestrial planets, so some properties such as isotopic signatures may vary. Some salt and clathrate hydrates have distinctive thermal properties that may activate some geological processes at these icy bodies. Their own formation or destruction involve relevant physical chemical changes that might be reflected in the geological activity.

  3. Minerals Policy Statement 1: planning and minerals

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-11-15

    Minerals Policy Statement 1 (MPS1) is the overarching planning policy document for all minerals, including coal, in England. It provides advice and guidance to planning authorities and the minerals industry and it will ensure that the need by society and the economy for minerals is managed in an integrated way against its impact on the environment and communities. The guidance covers methane extraction by drilling into unmined coal seams, capture of methane from coal mines and underground coal gasification. MPS1 replaces 'Minerals Planning Guidance (MPG1) Note 1: General considerations and the development plan system' and together with the annex on aggregates, completes the replacement of Minerals Planning Guidance (MPG6) Note 6: Guidelines for aggregates provision in England which are hereby cancelled. 4 annexes.

  4. GULF OF MEXICO SEAFLOOR STABILITY AND GAS HYDRATE MONITORING STATION PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    J. Robert Woolsey; Thomas M. McGee; Robin C. Buchannon

    2004-11-01

    The gas hydrates research Consortium (HRC), established and administered at the University if Mississippi's Center for Marine Research and Environmental Technology (CMRET) has been active on many fronts in FY 03. Extension of the original contract through March 2004, has allowed completion of many projects that were incomplete at the end of the original project period due, primarily, to severe weather and difficulties in rescheduling test cruises. The primary objective of the Consortium, to design and emplace a remote sea floor station for the monitoring of gas hydrates in the Gulf of Mexico by the year 2005 remains intact. However, the possibility of levering HRC research off of the Joint Industries Program (JIP) became a possibility that has demanded reevaluation of some of the fundamental assumptions of the station format. These provisions are discussed in Appendix A. Landmark achievements of FY03 include: (1) Continuation of Consortium development with new researchers and additional areas of research contribution being incorporated into the project. During this period, NOAA's National Undersea Research Program's (NURP) National Institute for Undersea Science and Technology (NIUST) became a Consortium funding partner, joining DOE and Minerals Management Service (MMS); (2) Very successful annual and semiannual meetings in Oxford Mississippi in February and September, 2003; (3) Collection of piston cores from MC798 in support of the effort to evaluate the site for possible monitoring station installation; (4) Completion of the site evaluation effort including reports of all localities in the northern Gulf of Mexico where hydrates have been documented or are strongly suspected to exist on the sea floor or in the shallow subsurface; (5) Collection and preliminary evaluation of vent gases and core samples of hydrate from sites in Green Canyon and Mississippi Canyon, northern Gulf of Mexico; (6) Monitoring of gas activity on the sea floor, acoustically and thermally; (7) Design, construction, and successful deployment of an in situ pore-water sampling device; (8) Improvements to the original Raman spectrometer (methane sensor); (9) Laboratory demonstration of the impact of bacterially-produced surfactants' rates of hydrate formation; (10) Construction and sea floor emplacement and testing--with both watergun and ship noise sources--of the prototypal vertical line array (VLA); (11) Initiation of studies of spatial controls on hydrates; (12) Compilation and analyses of seismic data, including mapping of surface anomalies; (13) Additional field verification (bottom samples recovered), in support of the site selection effort; (14) Collection and preliminary analyses of gas hydrates from new sites that exhibit variant structures; (15) Initial shear wave tests carried out in shallow water; (16) Isolation of microbes for potential medicinal products development; (17) Preliminary modeling of occurrences of gas hydrates.

  5. Electrical properties of polycrystalline methane hydrate

    Science.gov (United States)

    Du Frane, W. L.; Stern, L.A.; Weitemeyer, K.A.; Constable, S.; Pinkston, J.C.; Roberts, J.J.

    2011-01-01

    Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (?). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate ?. We determined the ? of CH4 hydrate to be 5 × 10?5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (?15 to 15°C). After dissociation back into ice, ? measurements of samples increased by a factor of ~4 and Ea increased by ~50%, similar to the starting ice samples.

  6. Phase Transition of Methane Gas Hydrate and Response of Marine Gas Hydrate Systems to Environmental Changes

    Science.gov (United States)

    Xu, W.

    2003-12-01

    Gas hydrates, which contain mostly methane as the gas component in marine sediment, are stable under relatively high pressure and low temperature conditions such as those found along continental margins and permafrost regions. Its stability is mostly controlled by in-situ pressure, temperature and salinity of pore fluid. Environmentally introduced changes in pressure and temperature can affect the stability of gas hydrate in marine sediment. While certain changes may enhance the process of gas hydrate formation, we are much more interested in the resultant dissociation processes, which may contribute to sub-marine slope instability, seafloor sediment failure, formation of mud volcanoes and pock marks, potential vulnerability of engineering structures, and the risk to drilling and production. We have been developing models to quantify phase transition processes of marine gas hydrates and to investigate the response of marine gas hydrate systems to environmental changes. Methane gas hydrate system is considered as a three-component (water, methane, salt) four-phase (liquid, gas, hydrate, halite) system. Pressure, temperature and salinity of pore fluid constrain the stability of gas hydrate and affect phase transition processes via their effects on methane solubility and fluid density and enthalpy. Compared to the great quantity of studies on its stability in the literature, in-depth research on phase transition of gas hydrate is surprisingly much less. A method, which employs pressure, enthalpy, salinity and methane content as independent variables, is developed to calculate phase transition processes of the three-component four-phase system. Temperature, an intensive thermodynamic parameter, is found not sufficient in describing phase transition of gas hydrate. The extensive thermodynamic parameter enthalpy, on the other hand, is found to be sufficient both in calculation of the phase transition processes and in modeling marine gas hydrate systems. Processes considered in this study to introduce gas hydrate dissociation in marine sediment include sedimentation, sea level drop and increasing seafloor temperature. Calculations indicate that dissociation of gas hydrates may lead to a build-up of excess pore pressure in marine sediment. The most significant factor constraining the magnitude of over-pressure is sediment permeability. The rate of sedimentation and pressure or temperature change at seafloor affects the degree and rate of gas hydrate dissociation and, hence, also the degree of excess pore pressure. The relationship between gas hydrate dissociation and the stability/failure of marine sediment are to be further discussed.

  7. EVOLUCIÓN MINERALÓGICA DEL CEMENTO PORTLAND DURANTE EL PROCESO DE HIDRATACIÓN / MINERALOGICAL EVOLUTION OF PORTLAND CEMENT DURING HYDRATION PROCESS

    Scientific Electronic Library Online (English)

    MANUEL ALEJANDRO, GIRALDO M..

    2006-03-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Se presenta la evolución mineralógica del cemento Pórtland tipo I durante el proceso de hidratación, usando las técnicas de caracterización de materiales difracción de rayos X (DRX) y microscopia electrónica de barrido (SEM), con el fin de entender los cambios que se dan en los minerales anhidros de [...] l cemento (alita, belita, celita y felita entre otros) durante su transformación en las fase estables hidratadas (tobermorita, ortlandita, etringita, etc.). Se encontró que, en general, el proceso de hidratación ocurre de manera diferente en cada mineral ya sea por la velocidad de reacción, o por los cambios cristalinos experimentados por éstos durante la transformación de fase anhidra a hidratada. Se pudo apreciar la formación de tobermorita gel (CSH), portlandita y etringita primaria. Además, como cambia la apariencia de la pasta a medida que avanza la hidratación. Abstract in english An investigation about mineralogical evolution during hydration process of the portland cement was carried out in this work using techniques of materials characterization, such as X ray diffraction (XRD) and scanning electron microscopy (SEM) in order to understand the behaviour shown by the differe [...] nt minerals of the cement (alite, belite, celite and felite) and their transformation in the stables hydrate phases (tobermorite, portlandite, ettringite) It was found that, in general, the hydration process happens in a different way in each mineral either because of the reaction speed, or the crystalline changes experienced by them in the transformation from the anhydrous to the hydrated phase. The tobermorite gel (CSH), portlandite and ettringitre formation and the changing in appearance of the paste during the hydration advances, could be appreciated.

  8. Examination of Portland cement paste hydrated in the presence of malic acid

    International Nuclear Information System (INIS)

    When malic acid (MA) solutions are added to ordinary Portland cement (OPC), rapid heat evolution takes place, but the hydration is retarded considerably at all the MA concentrations. To understand the mechanism of retardation, UV-visible and IR spectral studies were made and the results have revealed that some interaction occurs between MA and certain constituents of OPC. X-ray diffraction (XRD) and thermogravimetric (TG)/differential thermal analysis (DTA) studies have proved the formation of a new reaction product due to interaction between MA and some of the mineral phases of Portland cement. The retardation of the hydration of Portland cement may be attributed to the formation of this new compound

  9. Effects of CO2 hydrate on deep-sea foraminiferal assemblages

    International Nuclear Information System (INIS)

    This study, conducted with the Monterey Bay Aquarium Research Institute (MBARI), is the first to investigate potential effects of carbon dioxide (CO2) hydrates on benthic microfossils, specifically oraminifera. The experiment was conducted in September 2003 aboard the R/V Western Flier using the ROV Tiburon. Experimental (CO2 exposed) and control cores were collected at 3600m and stained to distinguish live (stained) from dead (unstained) individuals. Foraminifera are ideal for these investigations because of differing test composition (calcareous and agglutinated) and thickness, and diverse epifaunal and infaunal depth preferences. The effects of the CO2 on assemblages have been tracked both vertically (10cm depth) and horizontally, and between live and dead individuals. Increased mortality and dissolution of calcareous forms resulted from exposure to CO2 hydrate. Preliminary results suggest several major effects on surface sediment assemblages: 1) total number of foraminifera in a sample decreases; 2) foraminiferal diversity decreases in both stained and unstained specimens. The number of planktonic and hyaline calcareous tests declines greatly, with milliolids being more resistant to dissolution when stained; and 3) percentage of stained (live) forms is higher. Down-core trends (up to 10cm) indicate: 1) percent agglutinated forms decline and calcareous forms increasingly dominate; 2) agglutinated diversity decreases with depth; and 3) assemblages become increasinglpth; and 3) assemblages become increasingly similar with depth to those in control cores not subjected to CO2 hydrate. These results imply almost complete initial mortality and dissolution upon CO2 hydrate emplacement in the corrals. (Author)

  10. Study of the Natural Gas Hydrate 'Trap Zone' and the Methane Hydrate Potential in the Sverdrup Basin, Canada

    International Nuclear Information System (INIS)

    The methane hydrate stability zone beneath Sverdrup Basin has developed to a depth of 2 km underneath the Canadian Arctic Islands and 1 km below sea level under the deepest part of the inter-island sea channels. It is not, however, a continuous zone. Methane hydrates are detected in this zone, but the gas hydrate/free gas contact occurs rarely. Interpretation of well logs indicate that methane hydrate occurs within the methane stability zone in 57 of 150 analyzed wells. Fourteen wells show the methane hydrate/free gas contact. Analysis of the distribution of methane hydrate and hydrate/gas contact occurrences with respect to the present methane hydrate stability zone indicate that, in most instances, the detected methane hydrate occurs well above the base of methane hydrate stability. This relationship suggests that these methane hydrates were formed in shallower strata than expected with respect to the present hydrate stability zone from methane gases which migrated upward into hydrate trap zones. Presently, only a small proportion of gas hydrate occurrences occur in close proximity to the base of predicted methane hydrate stability. The association of the majority of detected hydrates with deeply buried hydrocarbon discoveries, mostly conventional natural gas accumulations, or mapped seismic closures, some of which are dry, located in structures in western and central Sverdrup Basin, indicate the concurring relationship of hydrate occurrence with areas of high heat ydrate occurrence with areas of high heat flow. Either present-day or paleo-high heat flows are relevant. Twenty-three hydrate occurrences coincide directly with underlying conventional hydrocarbon accumulations. Other gas hydrate occurrences are associated with structures filled with water with evidence of precursor hydrocarbons that were lost because of upward leakage

  11. Mineral Spectroscopy Server

    Science.gov (United States)

    George Rossman

    This server is primarily dedicated to providing information about color in minerals and access to data on mineral absorption in the visible, infrared, Raman and Mossbauer spectra. Both data coordinates and images of the spectra are available for selected minerals. Most data on the server were obtained in the Caltech mineral spectroscopy labs, but individuals throughout the world also contribute to this ever growing community resource. In addition to data files, the site provides an extensive list of references to papers on mineral optical spectroscopy. Citations are available sorted both by mineral name and by first authors of papers.

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

    International Nuclear Information System (INIS)

    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

  13. Precipitation of hydrated Mg carbonate with the aid of carbonic anhydrase for CO2 sequestration

    Science.gov (United States)

    Power, I. M.; Harrison, A. L.; Dipple, G. M.

    2011-12-01

    Strategies for sequestering CO2 directly from the atmosphere are likely required to achieve the desired reduction in CO2 concentration and avoid the most damaging effects of climate change [1]. Numerous studies have demonstrated the accelerated precipitation of calcium carbonate minerals with the aid of carbonic anhydrase (CA) as a means of sequestering CO2 in solid carbonate form; however, no study has examined precipitation of magnesium carbonate minerals using CA. Precipitation of magnesite (MgCO3) is kinetically inhibited [2]; therefore, Mg2+ must be precipitated as hydrated carbonate minerals. In laboratory experiments, the uptake of atmospheric CO2 into brine solutions (0.1 M Mg) was rate-limiting for the precipitation of dypingite [Mg5(CO3)4(OH)2-5H2O] with initial precipitation requiring 15 days [3]. It was also found that dypingite precipitation outpaced the uptake of CO2 gas into solution. CO2 uptake is limited by the hydration of CO2 to form carbonate ions [4]. Carbonic anhydrase (CA) enzymes are among the fastest known in nature and are able to catalyze the hydration of CO2, i.e., converting CO2(aq) to CO32- and HCO3- [5]. CA plays an important role in the carbon concentrating mechanism of photoautotrophic, chemoautotrophic, and heterotrophic prokaryotes and is involved in pH homeostasis, facilitated diffusion of CO2, ion transport, and the interconversion of CO2 and HCO3- [6]. Introducing CA into buffered Mg-rich solutions should allow for more rapid precipitation of hydrated magnesium carbonate minerals. Batch experiments were conducted using 125 mL flasks containing 100 mL of Millipore deionized water with 0.2 M of MgCl2-6H2O. To buffer pH, 1.0 g of pulverized brucite [Mg(OH)2] or 1.0 g of NaOH was added to the systems, which were amended with Bovine carbonic anhydrase (BCA) (Sigma-Aldrich). Solutions were stirred continuously and kept at room temperature (~22°C) with laboratory air introduced by bubbling. Temperature and pH were measured routinely and water was sampled for dissolved inorganic carbon (DIC) and magnesium concentrations. Final precipitates were collected for X-ray powder diffraction and determination of the percent carbon. The presence of BCA increases the concentration of DIC, thus accelerating the rate-limiting step. In alkaline Mg-rich solutions, disordered hydrated magnesium carbonate, resembling dypingite, rapidly precipitated within hours to form micron-wide flakes. At concentrations of 200 and 100 mg BCA/L, the rates of carbon uptake were ~7 and ~4.4 times that of the control system during the first 24 hours, respectively. BCA is able to catalyze the hydration of CO2 thereby increasing concentrations of DIC relatively rapidly and allowing for the sequestration of atmospheric CO2 as hydrated Mg carbonate minerals.

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

  15. Hydrate Equilibrium Measurement of Single CO2 and CH4 Hydrates Using Micro DSC

    Directory of Open Access Journals (Sweden)

    O. Nashed

    2014-01-01

    Full Text Available In this study, the simple gas hydrate equilibrium conditions of methane and carbon dioxide in water were measured by using high pressure micro DSC (why is the advantage. The technique was chosen because it is economic, fast and accurate. In this study, the methane hydrate equilibrium conditions were measured at pressure between 35-112 bar and temperature between 276-288 K. In addition, the carbon dioxide hydrate equilibrium conditions were measured at pressure between 15-37 bar and temperature between 274-282.5 K. The measured data was compared to the available literature data and the AADT % between the measured data and predicted model was calculated. Good agreements were obtained between the measured and literature data. The AADT% between the measured data and predicted models is less than 0.07% for CH4 hydrate and 0.15% for CO2 hydrate.

  16. Thermodynamic modeling for clathrate hydrates of ozone

    International Nuclear Information System (INIS)

    Highlights: • We present a phase-equilibrium model for ozone-containing clathrate hydrates. • We determine intermolecular potential parameters for O3. • There is good agreement between the developed model and the experimental data. • The results show the capability of O3 as a guest substance for clathrate hydrates. • We perform parametric studies for O3 storage capacity with various thermodynamic conditions. -- Abstract: We report a theoretical study to predict the phase-equilibrium properties of ozone-containing clathrate hydrates based on the statistical thermodynamics model developed by van der Waals and Platteeuw. The Patel–Teja–Valderrama equation of state is employed for an accurate estimation of the properties of gas phase ozone. We determined the three parameters of the Kihara intermolecular potential for ozone as a = 6.815 · 10?2 nm, ? = 2.9909 · 10?1 nm, and ? · kB?1 = 184.00 K. An infinite set of ?–? parameters for ozone were determined, reproducing the experimental phase equilibrium pressure–temperature data of the (O3 + O2 + CO2) clathrate hydrate. A unique parameter pair was chosen based on the experimental ozone storage capacity data for the (O3 + O2 + CCl4) hydrate that we reported previously. The prediction with the developed model showed good agreement with the experimental phase equilibrium data within ±2% of the average deviation of the pressure. The Kihara parameters of ozone showed slightly better suitability for the structure-I hydrate than CO2, which was used as a help guest. Our model suggests the possibility of increasing the ozone storage capacity of clathrate hydrates (?7% on a mass basis) from the previously reported experimental capacity (?1%)

  17. Complex admixtures of clathrate hydrates in a water desalination method

    Science.gov (United States)

    Simmons, Blake A. (San Francisco, CA); Bradshaw, Robert W. (Livermore, CA); Dedrick, Daniel E. (Berkeley, CA); Anderson, David W. (Riverbank, CA)

    2009-07-14

    Disclosed is a method that achieves water desalination by utilizing and optimizing clathrate hydrate phenomena. Clathrate hydrates are crystalline compounds of gas and water that desalinate water by excluding salt molecules during crystallization. Contacting a hydrate forming gaseous species with water will spontaneously form hydrates at specific temperatures and pressures through the extraction of water molecules from the bulk phase followed by crystallite nucleation. Subsequent dissociation of pure hydrates yields fresh water and, if operated correctly, allows the hydrate-forming gas to be efficiently recycled into the process stream.

  18. Rheological feedbacks between hydration, strain localization, and olivine deformation mechanisms in the oceanic lithosphere

    Science.gov (United States)

    Kohli, A. H.; Warren, J. M.

    2012-12-01

    Transform faults in the oceanic lithosphere play a key role in the tectonic water cycle by enabling deep circulation of seawater into the shallow lithosphere. We investigate dredge peridotite mylonite samples from the transform fault section of the Shaka Fracture Zone, Southwest Indian Ridge, in order to evaluate the relationships between hydration state, strain localization, and olivine deformation mechanisms. Initial petrographic analyses reveal growth of hydrous amphibole phases and mineral fluid inclusions, as well as the development of heterogeneous strain localization. To further investigate these features, we performed integrated electron backscatter diffraction and energy dispersive spectroscopy characterization. These analyses constrain the amphibole phase as tremolite and document hydration reaction textures associated with orthopyroxene porphyroclast tails and exsolution lamellae. Additionally, detailed examination of mylonitized zones illustrates systematic relationships between hydrous phase fraction, olivine grain size, and lattice preferred orientation (LPO). In particular, localized grain size reduction and absence of any LPO correlate with high hydrous phase fraction, while relatively coarse grained olivine with strong LPO are found in essentially monomineralic regions, suggesting likely feedbacks between hydration reactions, transitions in olivine deformation mechanisms, and mylonitization. We assess these relationships to develop a conceptual model for the concomitant hydration and deformation of peridotite in the brittle-ductile transition zone and evaluate implications for the rheological evolution of faults in the oceanic lithosphere.; (Left) Electron backscatter diffraction phase map. Blue - Forsterite, Cyan - Tremolite, Green - Opx, Red - Chromite. (Center) Average forsterite grain size and tremolite fraction as functions of position calculated in 50 ?m bins. (Right) M-indices for forsterite and tremolite as functions of position calculated in 50 ?m bins. The strong correlation of forsterite fabric strength with average grain size and tremolite fraction illustrates feedbacks between hydration, strain localization, and olivine deformation mechanisms.

  19. Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy

    OpenAIRE

    Carroll Susan A; Maxwell Robert S; Houston Jacqueline R

    2009-01-01

    Abstract Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline calcium (alumino-)silicate hydrate (Al-CSH) forms as a precursor solid to the cement mineral tobe...

  20. Vitamins and Minerals

    Science.gov (United States)

    ... through our food. Other minerals like chromium, copper, iodine, iron, selenium, and zinc are called trace minerals ... anemia is the most common type of anemia. Salt Most of the sodium we consume is in ...

  1. Marine electromagnetic methods for gas hydrate characterization

    Science.gov (United States)

    Weitemeyer, Karen Andrea

    Gas hydrate is a type of clathrate consisting of a gas molecule (usually methane) encased in a water lattice, and is found worldwide in marine and permafrost regions. Hydrate is important because it is a geo-hazard, has potential as an energy resource, and is a possible contributor to climate change. There are large uncertainties about the global amount of hydrate present, partly because the characterization of hydrate with seismic methods is unreliable. Marine electromagnetic (EM) methods can be used to image the bulk resistivity structure of the subsurface and are able to augment seismic data to provide valuable information about gas hydrate distribution in the marine environment. Marine controlled source electromagnetic (CSEM) sounding data from a pilot survey at Hydrate Ridge, located on the Cascadia subduction zone, show that regions with higher concentrations of hydrate are resistive. The apparent resistivities computed from the CSEM data are consistent for both apparent resistivity pseudosections and two-dimensional regularized inversion results. The 2D inversion results provide evidence of a strong resistor near the seismic bottom simulating reflector (BSR), and geologic structures are imaged to about a kilometer depth. Comparisons with electrical resistivity logging while drilling (LWD) data from Ocean Drilling Program Leg 204 show a general agreement except for one of three sites where the CSEM inversion shows a large resistor at depth as compared to the LWD. An overlay of the CSEM inversion with a collocated seismic line 230 from Trehu et al. (2001) exhibits remarkable similarities with the sedimentary layering, geologic structures, and the seismic BSR. Magnetotelluric (MT) sounding data collected simultaneously during the CSEM survey provide an electrical image of the oceanic crust and mantle (50 km depth) and the folding associated with the accretionary complex (top 2 km depth). In addition, the MT model provides a complementary low-resolution image of the CSEM inversion results. The CSEM data characterize the gas hydrate stability zone and both CSEM and MT map the geologic structures that allow methane to migrate to the gas hydrate stability zone.

  2. Hydration shells exchange charge with their protein

    Science.gov (United States)

    Abitan, H.; Lindgård, P.-A.; Nielsen, B. G.; Larsen, M. S.; Bohr, H. G.

    2010-09-01

    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. 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 (?-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity of the fluorescence background of the Raman spectrum with a typical relaxation time of 30-45 min. Second, we detect changes in the vibrational Raman spectra. To clarify these results we conducted similar experiments with aqueous solutions of amino acids and ethanol. These experiments led us to conclude that, without 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.

  3. Hydration shells exchange charge with their protein

    International Nuclear Information System (INIS)

    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. 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 (?-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity of the fluorescence background of the Raman spectrum with a typical relaxation time of 30-45 min. Second, we detect changes in the vibrational Raman spectra. To clarify these results we conducted similar experiments with aqueous solutions of amino acids and ethanol. These experiments led us to conclude that, without 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.

  4. Hydration shells exchange charge with their protein

    Energy Technology Data Exchange (ETDEWEB)

    Abitan, H; Lindgaard, P-A; Nielsen, B G; Larsen, M S; Bohr, H G, E-mail: Haim.abitan@gmail.co, E-mail: p.a.lindgard@risoe.d, E-mail: matamitos@gmail.co, E-mail: msl@aquaporin.d, E-mail: hbohr@fysik.dtu.d [QuP Centre, Department of Physics, Building 309, Technical University of Denmark, DK-2800, Kongens Lyngby (Denmark)

    2010-09-15

    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. 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 ({beta}-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity of the fluorescence background of the Raman spectrum with a typical relaxation time of 30-45 min. Second, we detect changes in the vibrational Raman spectra. To clarify these results we conducted similar experiments with aqueous solutions of amino acids and ethanol. These experiments led us to conclude that, without 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.

  5. Interaction of antifreeze proteins with hydrocarbon hydrates.

    Science.gov (United States)

    Ohno, Hiroshi; Susilo, Robin; Gordienko, Raimond; Ripmeester, John; Walker, Virginia K

    2010-09-10

    Recombinant antifreeze proteins (AFPs), representing a range of activities with respect to ice growth inhibition, were investigated for their abilities to control the crystal formation and growth of hydrocarbon hydrates. Three different AFPs were compared with two synthetic commercial inhibitors, poly-N-vinylpyrrolidone (PVP) and HIW85281, by using multiple approaches, which included gas uptake, differential scanning calorimetry (DSC) temperature ramping, and DSC isothermal observations. A new method to assess the induction period before heterogeneous nucleation and subsequent hydrate crystal growth was developed and involved the dispersal of water in the pore space of silica gel beads. Although hydrate nucleation is a complex phenomenon, we have shown that it can now be carefully quantified. The presence of AFPs delayed crystallization events and showed hydrate growth inhibition that was superior to that of one of the benchmark commercial inhibitors, PVP. Nucleation and growth inhibition were shown to be independent processes, which indicates a difference in the mechanisms required for these two inhibitory actions. In addition, there was no apparent correlation between the assayed activities of the three AFPs toward hexagonal ice and the cubic structure?II (sII) hydrate, which suggests that there are distinctive differences in the protein interactions with the two crystal surfaces. PMID:20623806

  6. Hydration shells exchange charge with their protein.

    Science.gov (United States)

    Abitan, H; Lindgård, P-A; Nielsen, B G; Larsen, M S; Bohr, H G

    2010-09-15

    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. 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 (?-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity of the fluorescence background of the Raman spectrum with a typical relaxation time of 30-45 min. Second, we detect changes in the vibrational Raman spectra. To clarify these results we conducted similar experiments with aqueous solutions of amino acids and ethanol. These experiments led us to conclude that, without 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. PMID:21386530

  7. Maternal hydration increases amniotic fluid index.

    Science.gov (United States)

    Kilpatrick, S J; Safford, K L; Pomeroy, T; Hoedt, L; Scheerer, L; Laros, R K

    1991-12-01

    Although adequate amniotic fluid (AF) volume is considered an important aspect of fetal well-being, the etiology of decreased AF volume is not well understood. A randomized blinded trial was designed to examine our hypothesis that maternal hydration would increase the AF index in women with low AF indexes. Women seen in our testing centers were randomized into control or hydration groups. The control group was instructed to drink their normal amount of fluid; the hydration group was instructed to drink 2 L of water, in addition to their usual amount of fluid, 2-4 hours before the post-treatment AF index. The women returned for the post-treatment AF index the same or following day. The mean post-treatment AF index was significantly greater in the hydration group (6.3 versus 5.1; P less than .01), as was the mean change in AF index (post-treatment AF index--pre-treatment AF index: 1.5 versus 0.31; P less than .01). These findings suggest that maternal oral hydration increases AF volume in women with decreased fluid levels. PMID:1945215

  8. Methane hydrates in quaternary climate change

    International Nuclear Information System (INIS)

    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)st this hypothesis. (Author)

  9. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    Science.gov (United States)

    Kwon, T.; Cho, G.; Santamarina, J.; Kim, H.; Lee, J.

    2009-12-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation captures the self-preservation behavior, calculates the hydrate and free gas quantities during dissociation, considering effective stress-controlled sediment compressibility and gas solubility in aqueous phase. Pore fluid pressure generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. Second, the analytical formulation for hydrate dissociation was incorporated as a user-defined function into a verified finite difference code (FLAC2D). The underlying physical processes of hydrate-bearing sediments, including hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, were coupled with the thermal conduction, pore fluid flow, and mechanical response of sediments. We conducted the simulations for a duration of 20 years, assuming a constant-temperature wellbore transferred heat to the surrounding hydrate-bearing sediments, resulting in dissociation of methane hydrate in the well vicinity. The model predicted dissociation-induced excess pore fluid pressures which resulted in a large volume expansion and plastic deformation of the sediments. Furthermore, when the critical stress was reached, localized shear failure of the sediment around the borehole was observed. In summary, the study indicates that the early stability of the sediment (i.e., when any hydrate is still present) is governed by the intensity of a heat source and the thermal conductivity of sediments. Later, the excess pore fluid pressure diffused from the dissociation region destabilizes the shallower sediments. In critical cases, an effective drainage path is necessary to prevent instability problems such as blow-up of sediments or buckling of a well.

  10. Gas Hydrates and Perturbed Permafrost: Can Thermokarst Lakes Leak Hydrate-Derived Methane?

    Science.gov (United States)

    Ruppel, C.; Walter, K.; Pohlman, J.; Wooller, M.

    2008-12-01

    Thermokarst lakes are common features in the continuous permafrost of Siberia, the Alaskan North Slope, and the Canadian Arctic and have been intensely studied as the loci of rapid and substantial methane flux to the atmosphere. Previous numerical modeling has constrained the conditions under which deep thermokarst lakes can develop organic-rich thaw bulbs (talik) tens of meters thick, and seismic surveys have imaged thaw bulbs more than 75 m thick beneath some thermokarst lakes. Microbial processes active in talik organic material are likely the predominant source for thermokarst methane emissions, although coalbed methane and methane associated with conventional hydrocarbons may contribute in some geologic settings. Here we evaluate the possibility that another source--methane released from dissociating gas hydrate--could contribute to methane emissions from these lakes. Temperatures within and beneath thermokarst lakes are significantly warmer than those in surrounding permafrost, and these relatively warm conditions can persist to depths several times greater than the thickness of the thaw bulb. For a 95-m-thick thaw bulb and a geothermal gradient consistent with the regional top of gas hydrate stability at ~200 m depth, the warmer temperatures beneath a thermokarst lake could lead to destabilization of up to 75 m of gas hydrate. Arguably, the presence of gas hydrate near the top of the stability zone in permafrost regions has not yet been observed. Nonetheless, the potential dissociation of such relatively shallow gas hydrate and the widespread availability in terrestrial settings of high permeability conduits (e.g., faults, sandy strata) that could facilitate the migration of hydrate-derived methane to the surface render this an important topic for future investigation. The susceptibility of permafrost gas hydrate zones to thermal perturbations is in sharp contrast to the situation in conventional marine hydrate provinces. There, gas hydrate first dissociates at the base of the stability zone, and upward migration of released methane may result in refreezing of the methane as gas hydrate. The shallow Arctic Ocean offers the opportunity to examine the interplay between both permafrost and marine gas hydrate stability processes in an area where thermokarst thaw bulbs flooded by Holocene sea level rise pierce relict permafrost. Large-scale climate change processes have already affected methane emissions from these now-offshore thermokarst systems. Onshore, the challenges will be determining the contribution (if any) of hydrate-derived methane in contemporary methane emissions using sophisticated analytical techniques and documenting past gas hydrate dissociation events, which are most likely to have coincided with past warming trends in the Arctic.

  11. Gas origin of hydrate in the Qilian Mountain permafrost, Qinghai

    Science.gov (United States)

    Lu, Z.; Zhu, Y.; Liu, H.; Zhang, Y.; Sun, Z.

    2012-12-01

    Gas origin of hydrate is not clear yet in the Muli of Qilian mountain permafrost, which will obviously affect its further exploration direction. A case is illustrated in the hole of DK-2 during gas hydrate drilling; gas composition and isotopes of gas hydrate and its associated gases are analyzed; organic geochemistry on mudstone, oily shale, coal, oil & gas indications are correlated within the interval of gas hydrate occurrences; the aim is to discuss the source of gases from gas hydrate and its implication to gas hydrate exploration in the study area. Results from gas composition and isotopes of gas hydrate and its associated gases reveal that the origin of gases from gas hydrate is mainly concomitant with deep oil or crude oil in the study area. Parameters for the abundance, type and thermal evolution of organic matter in mudstone, oil shale, coal in the same interval of gas hydrate occurrence suggest that these strata, especially within gas hydrate stability zone, play little role in gas sources for gas hydrate. Reservoir pyrolysis results for oil & gas indication-bearing cores reveal that oil & gas indications are closely associated with gas hydrate within its interval, indicating that they may serve as a sign of gas hydrate in the study area.

  12. Hydrate Formation and CH4 Production from Natural Gas Hydrates - Emphasis on Boundary Conditions and Production Methods

    OpenAIRE

    Birkedal, Knut Arne

    2009-01-01

    Natural gas hydrate is a solid state of gas and water at low temperature and high pressure. Gas hydrates are known to form hydrate plugs in production line, and has thus generally been considered a problem to the oil industry. However, the energy stored in gas hydrates is vast, and as the global energy demand increases, focus is shifted on gas hydrates as a potential energy resource. The work presented in this thesis is a series of experimental studies of hydrate formation and dissociatio...

  13. Mineral Properties Sheets

    Science.gov (United States)

    Dave Hirsch

    These sheets are designed to give students a framework for making observations of minerals in hand specimen and (for selected minerals) in thin section. I place most of the emphasis on the distinguishing properties, rather than requiring an exhaustive list. Students use hand specimen observation, thin section observation (for selected minerals) and references to complete the forms.

  14. The role of alumina on performance of alkali-activated slag paste exposed to 50 °C

    International Nuclear Information System (INIS)

    The strength and microstructural evolution of two alkali-activated slags, with distinct alumina content, exposed to 50 °C have been investigated. These two slags are ground-granulated blast furnace slag (containing 13% (wt.) alumina) and phosphorous slag (containing 3% (wt.) alumina). They were hydrated in the presence of a combination of sodium hydroxide and sodium silicate solution at different ratios. The microstructure of the resultant slag pastes was assessed by X-ray diffraction, differential thermogravimetric analysis, and scanning electron microscopy. The results obtained from these techniques reveal the presence of hexagonal hydrates: CAH10 and C4AH13 in all alkali-activated ground-granulated blast-furnace slag pastes (AAGBS). These hydrates are not observed in pastes formed by alkali-activated ground phosphorous slag (AAGPS). Upon exposure to 50 °C, the aforementioned hydration products of AAGBS pastes convert to C3AH6, leading to a rapid deterioration in the strength of the paste. In contrast, no strength loss was detected in AAGPS pastes following exposure to 50 °C. -- Highlights: •Strength of alkali-activated slag (AAS) pastes after exposure to 50 °C is studied. •AAS pastes with high alumina content lose strength after the exposure. •C4AH13 and CAH10 form in these AAS pastes. •Conversion of these calcium alumina hydrates is associated with the strength loss. •AAS pastes with low alumina content maintain its strength after the exposure

  15. The role of alumina on performance of alkali-activated slag paste exposed to 50 °C

    Energy Technology Data Exchange (ETDEWEB)

    Jambunathan, N. [Department of Civil Engineering, Monash University, Clayton, Victoria 3800 (Australia); Sanjayan, J.G. [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria (Australia); Pan, Z., E-mail: zhu.pan@monash.edu [Department of Civil Engineering, Monash University, Clayton, Victoria 3800 (Australia); Li, G. [School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009 (Australia); Liu, Y. [School of Geosciences and Info-Physics, Central South University, Changsha 410083 (China); Korayem, A.H.; Duan, W.H.; Collins, F. [Department of Civil Engineering, Monash University, Clayton, Victoria 3800 (Australia)

    2013-12-15

    The strength and microstructural evolution of two alkali-activated slags, with distinct alumina content, exposed to 50 °C have been investigated. These two slags are ground-granulated blast furnace slag (containing 13% (wt.) alumina) and phosphorous slag (containing 3% (wt.) alumina). They were hydrated in the presence of a combination of sodium hydroxide and sodium silicate solution at different ratios. The microstructure of the resultant slag pastes was assessed by X-ray diffraction, differential thermogravimetric analysis, and scanning electron microscopy. The results obtained from these techniques reveal the presence of hexagonal hydrates: CAH{sub 10} and C{sub 4}AH{sub 13} in all alkali-activated ground-granulated blast-furnace slag pastes (AAGBS). These hydrates are not observed in pastes formed by alkali-activated ground phosphorous slag (AAGPS). Upon exposure to 50 °C, the aforementioned hydration products of AAGBS pastes convert to C{sub 3}AH{sub 6}, leading to a rapid deterioration in the strength of the paste. In contrast, no strength loss was detected in AAGPS pastes following exposure to 50 °C. -- Highlights: •Strength of alkali-activated slag (AAS) pastes after exposure to 50 °C is studied. •AAS pastes with high alumina content lose strength after the exposure. •C{sub 4}AH{sub 13} and CAH{sub 10} form in these AAS pastes. •Conversion of these calcium alumina hydrates is associated with the strength loss. •AAS pastes with low alumina content maintain its strength after the exposure.

  16. Queensland mineral comodity report: mineral sands

    International Nuclear Information System (INIS)

    The current status of the heavy mineral sands industry in Queensland is reviewed. The main minerals sought are rutile, ilmenite, zircon and monazite. Of these the titanium bearing minerals, rutile and ilmenite are the most important. A description of their phisical and chemical characteristics is given. It is shown that they occur in the Pleistocene to recent coastal deposits of beaches and dune systems backed by sand plains. These areas fringe the Queensland coastline almost continuously with average thicknesses from 25 to 30 meters. The status of current producers , production methods and rates are also briefly discussed. 12 refs., 2 tabs., 3 figs

  17. Fuel cell membrane hydration and fluid metering

    Science.gov (United States)

    Jones, Daniel O. (Glenville, NY); Walsh, Michael M. (Fairfield, CT)

    2003-01-01

    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. 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).

  18. 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 ?-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the ?-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 ?-ray-irradiated propane hydrate with deuterated water.

  19. Apparatus investigates geological aspects of gas hydrates

    Science.gov (United States)

    Booth, J.S.; Winters, W.J.; Dillon, William P.

    1999-01-01

    The US Geological Survey has developed a laboratory research system which allows the study of the creation and dissociation of gas hydrates under deepwater conditions and with different sediment types and pore fluids. The system called GHASTLI (gas hydrate and sediment test laboratory instrument) comprises a pressure chamber which holds a sediment specimen, and which can simulate water depths to 2,500m and different sediment overburden. Seawater and gas flow through a sediment specimen can be precisely controlled and monitored. It can simulate a wide range of geology and processes and help to improve understanding of gas hydrate processes and aid prediction of geohazards, their control and potential use as an energy source. This article describes GHASTLI and how it is able to simulate natural conditions, focusing on fluid volume, acoustic velocity-compressional and shear wave, electric resistance, temperature, pore pressure, shear strength, and permeability.

  20. Miners-Iron test of optical fibers

    International Nuclear Information System (INIS)

    An experiment is described in which a number of optical fibers will be exposed to nuclear radiation in the Miners-Iron event at the Nevada Test Site. Two polymer clad silicon fibers and a borosilicate clad fiber will experience a dose of several Mrads, while a second set will experience about 0.1 Mrad. Attenuation and luninescence experiments are planned. Optic fibers will also be used for cables

  1. Ground movements associated with gas hydrate production

    International Nuclear Information System (INIS)

    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

  2. Petrophysical Properties Of Sandy Sediments Possibly Hosting Gas Hydrate In The Eastern Margin Of Japan Sea

    Science.gov (United States)

    Uchida, T.; Takashima, I.; Sunaga, H.; Sasaki, S.; Matsumoto, R.

    2011-12-01

    In 2010 the MD179 project was undertaken by the Marion Dufresne aiming at recovery of deep seated gas and gas hydrate, methane induced carbonate, and deep sediments older than 300 ka in order to develop geologic model of gas hydrate accumulation and evaluate the possible environmental impact of gas hydrate for the last glacial-interglacial cycles. Sediment samples below the seafloor were obtained in the Umitaka Spur, Joetsu Channel, Toyama Trough, Japan Basin, Nishi Tsugaru and Okushiri Ridge areas by the MD179 cruise. Small amounts of sandy sediment have been retrieved as thin intercalations in Pleistocene and Holocene silty layers, where trace fossils and strong bioturbations are commonly observed. Those sandy sediments consist of very fine- to fine-grained sand grains, and are sometimes tuffaceous. Pore-size distribution measurements and thin-section observations of these arenite sands were undertaken, which indicatesd that porosities of muddy sediments are around 50 % but those of arenites range from 42 to 52 %, of which mean pore sizes and permeabilities are larger than those of siltstones and mudstones. These coarser sediments might have been transported approximately around 3 to 30 ka, where supplying sediments may not be abundant due to sea level fluctuation during the Pleistocene ice age. While the presence of gas hydrate in intergranular pores of arenite sands has not been confirmed, the soupy occurrence in recovered sediments may strongly indicate the presence of gas hydrate filling the intergranular pore system of arenite sands that is called pore-space hydrates. They have been recognized till now in the Mallik as well as in the Nankai Trough areas, which are considered to be very common even in the subsurface sandy sediments at the eastern margin of Japan Sea. Concentration of gas hydrate may need primary intergranular pores large enough to occur within a host sediment that may be arenite sand without matrix grains deposited in the sedimentary environment such as deep sea channels. The geological modeling of the gas hydrate formation and evolution system is concerned for energy resource potential in the Japan Sea as well as the Nankai Trough areas. Time of deposition of coarse-grained sediments can be recognized by the thermoluminescence (TL) dating method. TL dating works on the principle that materials containing naturally occurring radioactive isotopes such as uranium, thorium or potassium are subject to low levels of radiation. In mineral crystals, this leads to ionization of the atoms in the host material and freed electrons may become trapped in structural defects or holes in the mineral crystal lattice. These electrons can be released by heating under controlled conditions, and an emission of light occurs which is the basis of TL dating. Additionally they usually provide information about the provenance and the paleoenvironment when the sediments deposited. This study was performed as a part of the MH21 Research Consortium on methane hydrate in Japan.

  3. Eucalyptus obliqua seedling growth in organic vs. mineral soil horizons.

    Science.gov (United States)

    Barry, Karen M; Janos, David P; Nichols, Scott; Bowman, David M J S

    2015-01-01

    Eucalyptus obliqua, the most widespread timber tree in Tasmania, is a pioneer after fire which can eliminate the organic layer of forest soil, exposing the underlying mineral soil. We compared seedling growth, mycorrhiza formation, and mineral nutrient limitation in organic layer vs. mineral soil. We grew E. obliqua seedlings separately in pots of organic layer and mineral soil in a glasshouse. Additional treatments of organic soil only, involved fully crossed methyl-bromide fumigation and fertilization. Fertilization comprised chelated iron for 121 days after transplant (DAT) followed by soluble phosphorus. At 357 DAT, whole plant dry weight was three times greater in ambient organic than in mineral soil. In organic soil, fumigation halved ectomycorrhiza abundance and reduced seedling growth at 149 DAT, but by 357 DAT when negative effects of fumigation on seedling growth had disappeared, neither fumigation nor fertilization affected mycorrhiza abundance. Iron fertilization diminished seedling growth, but subsequent phosphorus fertilization improved it. E. obliqua seedlings grow much better in organic layer soil than in mineral soil, although phosphorus remains limiting. The prevalent forestry practice of burning to mineral soil after timber harvest exposes a poor growth medium likely only partially compensated by fire-induced mineral soil alterations. PMID:25750650

  4. Fissure minerals, literature review

    International Nuclear Information System (INIS)

    This paper is a review of methods used for direct and indirect dating of tectonic events. Isotope geochemistry including stable isotopes as well as fission track- dating, fluid inclusion and thermoluminescens techniques have been considered. It has been concluded that an investigation of tectonic (and thermal) events should start with a detailed study of the mineral phases grown in seald fissures as well as minerals from fissure walls. This study should include phase identification, textures as well as mineral chemistry. The information from this study is fundamental for the decision of further investigations. Mineral chemistry including isotopes and fluid inclusion studies will give an essential knowledge about crystallization conditions for fissure minerals concerned. Direct dating using fission tracks as well as radioactive isotopes could be useful for some minerals. Application of thermoluminescens dating on fissure minerals is doubtful. (Auth.)

  5. Microbial Community Structure and Diversity in Hydrate Ridge Gas Hydrates (Cascadia Margin)

    Science.gov (United States)

    Lösekann, T.; Knittel, K.; Boetius, A.; Amann, R.

    2003-04-01

    Here, we present the first quantitative study investigating microorganisms physically associated with Hydrate Ridge gas hydrates. Previous studies have shown that the anaerobic oxidation of methane (AOM) in methane enriched surface sediments of Hydrate Ridge is apparently mediated by highly structured microbial consortia (Boetius et al., 2000). These AOM consortia consist of an inner core of methane-oxidizing archaea (ANME2-group) and an outer shell of sulfate-reducing bacteria (Desulfosarcina/Desulfococcus group). However, recently other microbial associations have been found capable of oxidizing methane anaerobically (e.g. Michaelis et al., 2002; Orphan et al., 2002). Only little is known about microorganisms mediating AOM in direct association with gas hydrates (Lanoil et al., 2001). The microbial community in pure melted gas hydrates sampled at the southern summit of Hydrate Ridge, coast off Oregon (USA), was analyzed by fluorescence in situ hybridization (FISH). Additionally, microbial diversity was studied using 16S rDNA clone libraries for Bacteria and Archaea. First FISH experiments confirm the abundance of AMNE1-group archaea and ANME2-group archaea in pure melted Hydrate Ridge gas hydrates. The abundance of these AOM mediating groups seems to be orders of magnitude lower than in the gas hydrate surrounding sediment. ANME1-cells were detected as filamentous free-living rods. Archaea of the ANME2-group were found in associations. In contrast to the known highly structured Hydrate ridge consortia, these cells are only loosly aggregated. The obtained molecular data will be compared with results of previous studies, which dealt with the microbial diversity in methane enriched surface sediments of Hydrate Ridge. References: Boetius, A., Ravenschlag, K. , Schubert, C., Rickert, D., Widdel, F., Gieseke, A., Amann, R., Jørgensen, B. B., Witte, U. &Pfannkuche, O.: A marine microbial consortium apparently mediating anaerobic oxidation of methane. Nature 407, 623--626, 2000. Lanoil, B. D., Sassen, R., La Duc, M. T., Sweet, S. T., Nealson, K. H.: Bacteria and Archaea physically associated with Gulf of Mexico gas hydrates. Appl. Environ. Microbiol. 67, 5143--5153, 2001. Michaelis, W., Seifert, R., Nauhaus, K., Treude, T., Thiel, V., Blumenberg, M., Knittel, K., Gieseke, A., Peterknecht, K., Pape, T., Boetius, A., Amann, R., Jørgensen, B. B., Widdel, F., Peckmann, J., Pimenov, N. V. &Gulin, M. B.: Microbial reefs in the Black Sea fueled by anaerobic oxidation of methane. Science 297, 1013--1015, 2002. Orphan, V. J., House, C. H., Hinrichs, K.-U., McKeegan, K. D. &DeLong, E. F.: Multiple archaeal groups mediate methane oxidation in anoxic cold seep sediments. Proceedings of the National Academy of Sciences of the United States of America 99, 7663--7668, 2002.

  6. Controls on Regional Gas Hydrate Occurrence at Southern Hydrate Ridge (ODP Leg 204)-Geochemical Evidence

    Science.gov (United States)

    Claypool, G. E.; Milkov, A. V.; Lee, Y.; Torres, M. E.; Borowski, W. S.; Tomaru, H.; Leg 204 Science Party, .

    2003-12-01

    Ocean Drilling Program Leg 204 on southern Hydrate Ridge found concentrated gas hydrate (20-40% of pore volume) only in shallow (0-30 m) sediments over a limited area (0.3 x 0.5 km) at the summit of the Ridge, just above seismically imaged gas migration pathways. Although summit gas hydrates are dominated by microbial methane (? 13C = -65 permil), the hydrates contain thermogenic ethane (? 13C = -34 permil) and sediments cored within the migration conduits contain elevated amounts of C2-C6 hydrocarbons having carbon isotopic compositions indicating hydrocarbon origin at temperatures on the order of 120-140 deg C. At sites away from the summit of southern Hydrate Ridge, gas hydrate occurrence is more limited, with average contents on the order 1-3% of pore volume. Non-summit sites have no significant input of migrated thermogenic hydrocarbons to the hydrate stability zone. However, intense microbial activity results in relatively steep (1.6 to 3.6 mM/m) methane concentration gradients, and a top of gas hydrate occurrence marked by distinctive hydrocarbon fractionation (ethane depletion, propane enrichment) in the dissolved gas geochemistry. Ethane in shallow sediments is isotopically light (? 13C = -52 permil) and probably related to microbial acetogenesis and carboxyl group reduction. Formation of Structure I methane hydrate involves a fourfold ethane-enrichment in the hydrate relative to the dissolved gas phase, and results in a net transfer of ethane from the pore water to the sediment. Steep porosity gradients result in the burial velocity of sediment being greater than that of pore water with respect to the sediment-seawater interface. Downward sediment velocity is even greater relative to the base of gas hydrate stability, which is shoaling due to tectonic uplift concurrent with sedimentation. Decomposition of ethane-enriched gas hydrate upon subsidence beneath the stability zone results in transfer of ethane from the sediment back to dissolved gas/free gas phases, and produces large shifts in C1/C2 ratio. Carbon isotopic composition of dissolved inorganic carbon indicates that anaerobic methane oxidation is an important process mainly in the summit region. At most non-summit sites, rapid burial apparently limits the amount of methane diffusing upward to the sulfate reduction zone.

  7. Characterization of mixed CO2 + TBPB hydrates for refrigeration applications

    OpenAIRE

    Clain, P.; Delahaye, A.; Fournaison, L.; Jerbi, S.; Mayoufi, N.; Dalmazzone, D.; Fu?rst, W.

    2011-01-01

    / The present work investigates the use of semiclathrate hydrates, formed from CO2 + tetra-nbutylphosphonium bromide (TBPB) + water mixtures, as appropriate media for cold storage and distribution in refrigeration applications. Previous studies show that these hydrates are able to trap molecules of carbon dioxide resulting in mixed hydrates. Calorimetry devices were used for determining the dissociation enthalpies of mixed CO2 + TBPB hydrates under various stability conditions (P, T) and salt...

  8. A Review on Carbon Dioxide Hydrate Potential in Technological Applications

    OpenAIRE

    Mukhtar, H.; Azmi, N.; Sabil, K. M.

    2011-01-01

    The enticing characteristics of carbon dioxide hydrates initiate numerous research activities around the globe and in a wide variety of fields from carbon dioxide sequestration to cool storage applications. A general introduction to clathrate hydrates and carbon dioxide hydrates in particular has been discussed. The motivations behind carbon dioxide hydrate research and the general fields of interest for these compounds are briefly explained in this study.

  9. A Review on Carbon Dioxide Hydrate Potential in Technological Applications

    Directory of Open Access Journals (Sweden)

    H. Mukhtar

    2011-01-01

    Full Text Available The enticing characteristics of carbon dioxide hydrates initiate numerous research activities around the globe and in a wide variety of fields from carbon dioxide sequestration to cool storage applications. A general introduction to clathrate hydrates and carbon dioxide hydrates in particular has been discussed. The motivations behind carbon dioxide hydrate research and the general fields of interest for these compounds are briefly explained in this study.

  10. Creeping deformation mechanisms for mixed hydrate-sediment submarine landslides

    Science.gov (United States)

    Mountjoy, Joshu; Pecher, Ingo; Henrys, Stuart; Barnes, Philip; Plaza-Faverola, Andreia

    2013-04-01

    Globally widespread gas hydrates are proposed to stabilize the seafloor by increasing sediment peak shear strength; while seafloor failure localises at the base of the gas hydrate stability field (BGHS). The primary mechanism by which gas hydrates are proposed to induce slope failure is by temperature or pressure controlled dissociation of hydrate to free gas resulting in a significant pore pressure increase at the BGHS. Direct evidence for this process is lacking however, and the interaction between gas hydrate and seafloor stability remains poorly understood. We present evidence that, contrary to conventional views, gas hydrate can itself destabilize the seafloor. Morphological (Kongsberg-Simrad EM300 and EM302 multibeam) and high-resolution multichannel seismic refection data from a 100 km2 submarine landslide complex in ~450 m water depth, 20 km off the east coast of New Zealand indicate flow-like deformation within gas hydrate-bearing sediments. This "creeping" deformation occurs immediately downslope of where the BGHS reaches the seafloor, as indicated by a hydrate-indicating bottom simulating reflector (BSR) cutting through the landslide debris, suggesting involvement of gas hydrates. We propose two mechanisms to explain how the shallow gas hydrate system could control these landslides. 1) The Hydrate Valve: Overpressure and/or temperature fluctuations below low-permeability gas hydrate-bearing sediments causes hydrofracturing where the BGHS approaches the landslide base, both weakening sediments and creating a valve for transferring excess pore pressure into the upper landslide body. 2) Hydrate-sediment Glacier: Gas hydrate-bearing sediment exhibits time-dependent plastic deformation enabling glacial-style deformation. This second hypothesis is supported by recent laboratory observations of time-dependent behaviour of gas-hydrate-bearing sands. Given the ubiquitous occurrence of gas hydrates on continental slopes, our results may require a re-evaluation of slope stability following future climate-forced variation in bottom water temperatures.

  11. Study on hydration of titanium base alloys during electrochemical machining

    International Nuclear Information System (INIS)

    The surface hydration of parts and tool electrodes, manufactured from the same blank during electrochemical machining in electrolytes (15%NaCl) is investigated. It is shown that hydration of surfaces in tool electrodes of VT15, VT14 alloys is considerably lower than the surface hydration of parts made from the same alloys. It is pointed out that the degree of hydration greatly depends on the effectiveness of destruction of protective films on titanium alloys

  12. Photophysical properties of hydrated electron clusters

    International Nuclear Information System (INIS)

    The photophysical properties of hydrated electron clusters were studied in order to gain insight into the understanding of the aqueous solvated electron. Vertical detachment energies, (VDE), determined for these clusters via photoelectron spectroscopy indicated the excess electron resides in an internal state. Further, the measured angular distribution of ejected photoelectrons indicate this electron is mostly of s type character. The authors show these clusters undergo photofragmentation upon excitation near threshold. A simple model based upon a critical photoelectron kinetic energy, Ec, reproduces the experimental data. The absorption spectrum of selected hydrated electron clusters was measured and was found to reproduce the features of the known spectrum of the aqueous electron

  13. Experimental Study of Gas Hydrate Dynamics

    Science.gov (United States)

    Fandino, O.; Ruffine, L.

    2011-12-01

    Important quantities of methane and other gases are trapped below the seafloor and in the permafrost by an ice-like solid, called gas hydrates or clathrate hydrates. The latter is formed when water is mixing with different gases at high pressures and low temperatures. Due to a their possible use as a source of energy [1] or the problematic related to flow assurance failure in pipelines [2] the understanding of their processes of formation/destabilisation of these structures becomes a goal for many laboratories research as well as industries. In this work we present an experimental study on the stochastic behaviour of hydrate formation from a bulk phase. The method used here for the experiments was to repeat several time the same hydrate formation procedure and to notice the different from one experiment to another. A variable-volume type high-pressure apparatus with two sapphire windows was used. This device, already presented by Ruffine et al.[3], allows us to perform both kinetics and phase equilibrium measurements. Three initial pressure conditions were considered here, 5.0 MPa, 7.5 MPa and 10.0 MPa. Hydrates have been formed, then allowed to dissociate by stepwise heating. The memory effect has also been investigated after complete dissociation. It turned out that, although the thermodynamics conditions of formation and/or destabilization were reproducible. An attempt to determine the influence of pressure on the nucleation induction time will be discussed. References 1. Sum, A. K.; Koh, C. A.; Sloan, E. D., Clathrate Hydrates: From Laboratory Science to Engineering Practice. Industrial & Engineering Chemistry Research 2009, 48, 7457-7465. 2. Sloan, E. D., A changing hydrate paradigm-from apprehension to avoidance to risk management. Fluid Phase Equilibria 2005, 228, 67-74. 3. Ruffine, L.; Donval, J. P.; Charlou, J. L.; Cremière, A.; Zehnder, B. H., Experimental study of gas hydrate formation and destabilisation using a novel high-pressure apparatus. Marine and Petroleum Geology 2010, 27, (6), 1157-1165.

  14. Structure of nanocrystalline calcium silicate hydrates

    OpenAIRE

    Grangeon, Sylvain; Claret, Francis; Lerouge, Catherine; Lanson, Bruno

    2014-01-01

    Nanocrystalline calcium silicate hydrates (C-S-H) are the main hydration products and the main binging phases in many types of cement, including ordinary Portland cement. As a result of its ubiquity is these engineered systems, C-S-H controls main cement physical and chemical properties. These properties depend on C-S-H calcium to silicon atomic ratio (Ca/Si), which is commonly described as ranging between 0.6 and 2.3. This means that C-S-H structure dictates cement macroscopic properties. As...

  15. Method for preparation of hydrated zircopiur dioxide

    International Nuclear Information System (INIS)

    Preparation of acid-resistant hydrated zirconium dioxide including treatment of zirconium salt aqueous solution with an alkaline reagent, precipitation, drying and washing of the sediment is described. Precipitation is carried out at 180-g 200 deg from solutions containing 140-160 g/l of zirconium dioxide. Carbamide in amount of 0.5-0.7 g per 1 kg of zirconium dioxide is used as an alkaline reagent. The given method permits to expand the possibility of using hydrated zirconium dioxide as a sorbent in acidic media (pH<2). Besides that it becomes possible to realize multiple use of sorbent due to its regeneration in acidic media

  16. Hydration Energies of Protonated and Sodiated Thiouracils

    OpenAIRE

    Wincel, Henryk

    2014-01-01

    Hydration reactions of protonated and sodiated thiouracils (2-thiouracil, 6-methyl-2-thiouracil, and 4-thiouracil) generated by electrospray ionization have been studied in a gas phase at 10 mbar using a pulsed ion-beam high-pressure mass spectrometer. The thermochemical data, ?Hon, ?Son, and ?Gon, for the hydrated systems were obtained by equilibrium measurements. The water binding energies of protonated thiouracils, [2SU]H+ and [6Me2SU]H+, were found to be of the order of 51 kJ/mol for...

  17. Confined water in the low hydration regime

    CERN Document Server

    Gallo, P; Rovere, M

    2002-01-01

    Molecular dynamics results on water confined in a silica pore in the low hydration regime are presented. Strong layering effects are found due to the hydrophilic character of the substrate. The local properties of water are studied as function of both temperature and hydration level. The interaction of the thin films of water with the silica atoms induces a strong distortion of the hydrogen bond network. The residence time of the water molecules is dependent on the distance from the surface. Its behavior shows a transition from a brownian to a non-brownian regime approaching the substrate in agreement with results found in studies of water at contact with globular proteins.

  18. Chelated minerals for poultry

    Scientific Electronic Library Online (English)

    SL, Vieira.

    2008-06-01

    Full Text Available Organic minerals have been subject of an increasing number of investigations recently. These compounds can be considered the most significant event regarding commercial forms of minerals targeting animal supplementation in the last decades. Minerals, especially metals, are usually supplemented in po [...] ultry feeds using cheap saline sources and have never required a lot of attention in terms of quality. On the other hand, definitions of organic minerals are very broad and frequently lead to confusion when decision-making becomes necessary. Organic minerals include any mineral bound to organic compounds, regardless of the type of existing bond between mineral and organic molecules. Proteins and carbohydrates are the most frequent candidates in organic mineral combinations. Organic fraction size and bond type are not limitations in organic mineral definition; however, essential metals (Cu, Fe, Zn, and Mn) can form coordinated bonds, which are stable in intestinal lumen. Metals bound to organic ligands by coordinated bonds can dissociate within animal metabolism whereas real covalent bonds cannot. Chelated minerals are molecules that have a metal bound to an organic ligand through coordinated bonds; but many organic minerals are not chelates or are not even bound through coordinated bonds. Utilization of organic minerals is largely dependent on the ligand; therefore, amino acids and other small molecules with facilitated access to the enterocyte are supposed to be better utilized by animals. Organic minerals with ligands presenting long chains may require digestion prior to absorption. After absorption, organic minerals may present physiological effects, which improve specific metabolic responses, such as the immune response. Many studies have demonstrated the benefits of metal-amino acid chelates on animal metabolism, but the detection positive effects on live performance is less consistent.

  19. Experimental investigation into scaling models of methane hydrate reservoir

    International Nuclear Information System (INIS)

    Highlights: • The scaling criteria for methane hydrate reservoir are built. • The scaling criteria are verified by the experiments in two 3-D simulators. • The scaling criteria are used for predicting gas production of real hydrate reservoir. • Methane of 1.168 × 106 m3 is produced from the hydrate reservoir after 13.9 days. - Abstract: The Cubic Hydrate Simulator (CHS), a three-dimensional 5.8 L cubic pressure vessel, and the Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8 L pressure vessel, are used for investigating the production processes of hydrate. The gas production behaviors of methane hydrate in the porous media using the thermal stimulation method with a five-spot well system are studied. The experimental conditions are designed by a set of scaling criteria for the gas hydrate reservoir. The experimental results verify that the scaling criteria for gas hydrate production are reliable. The scaling criteria are used for predicting the production behavior of the real-scale hydrate reservoir. In the model of the real-scale hydrate reservoir with the size of 36 m × 36 m × 36 m, methane of 1.168 × 106 m3 (STP) is produced from the hydrate reservoir during 13.9 days of gas production. It is obtained that the gas recovery is 0.73, and the final energy efficiency is 9.5

  20. Investigation on a novel reactor for gas hydrate production

    International Nuclear Information System (INIS)

    Highlights: ? We develop a novel reactor for fast and continuous production of methane hydrates. ? Reactor forms hydrates by injection of water through spray nozzles. ? The method maximizes interfacial area between reactants. ? The method also minimizes mass transfer barriers and thermal effects. ? We obtain methane hydrates in some 10 min only with SDS surfactant promotion. -- Abstract: Gas hydrates have a large capacity for the storage of gases and are an attractive method for gas filtration and transportation. However, hydrate formation is usually controlled by the rate of crystallization and thus it can be a slow process. A technology that will rapidly and continuously form hydrate is necessary for scale-up. A novel reactor with an inner volume of 25 l has been designed, built and installed to form hydrates by injection of water through spray nozzles from the top of the methane-filled reactor. This method allows to maximize interfacial area between reactants and to minimize mass transfer barriers and thermal effects that negatively affect conversion of reactants into hydrate. A system was developed to remove heat released during hydrate formation, and to reach a good level of temperature control inside the reactor. A novel system for hydrate recovering and unloading was also designed. The objective of experimentation is to lower energetic costs of hydrate formation, also through surfactant promotion. Anionic surfactant sodium dodecyl sulfate, SDS, was tested. Results of a first set of experimental applications of the reactor for rapid methane hydrate formation are presented.

  1. Elastic properties of gas hydrate-bearing sediments

    Science.gov (United States)

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

    2001-01-01

    Downhole-measured compressional- and shear-wave velocities acquired in the Mallik 2L-38 gas hydrate research well, northwestern Canada, reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate-bearing sediments is as a pore-filling constituent. As opposed to high elastic velocities predicted from a cementation theory, whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities, the velocity increase from gas hydrate saturation in the sediment pore space is small. Both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration, similar to the field-observed velocities; however, the weighted equation more accurately describes the compressional- and shear-wave velocities of gas hydrate-bearing sediments. A decrease of Poisson's ratio with an increase in the gas hydrate concentration is similar to a decrease of Poisson's ratio with a decrease in the sediment porosity. Poisson's ratios greater than 0.33 for gas hydrate-bearing sediments imply the unconsolidated nature of gas hydrate-bearing sediments at this well site. The seismic characteristics of gas hydrate-bearing sediments at this site can be used to compare and evaluate other gas hydrate-bearing sediments in the Arctic.

  2. Preparation and Analysis of Multiple Hydrates of Simple Salts

    Science.gov (United States)

    Schaeffer, Richard W.; Chan, Benny; Marshall, Shireen R.; Blasiole, Brian; Khan, Neetha; Yoder, Kendra L.; Trainer, Melissa E.; Yoder, Claude H.

    2000-04-01

    We have developed a laboratory project in which the student prepares a series of hydrates of simple salts and then determines the extent of hydration of the product(s). We believe this provides a good introduction to the concepts of solubility, saturation, recrystallization, relative compound stability (e.g., a dihydrate vs tetrahydrate at elevated temperature), and simple gravimetric analysis. Moreover, the project lends itself to many variations. For example, a student could be given a "starting" hydrated salt and asked to prepare another hydrate within a specified temperature range. Or students could be given the formulas of several hydrates stable over different temperature ranges and be asked to "discover" a method of preparation. If it is deemed desirable to extend the project, the cation and/or anion could be determined quantitatively. The preparation of ionic hydrates is accomplished by four methods: (i) slow evaporation of the solvent from a near saturated solution of the starting hydrate at a temperature within the stability range of the desired hydrate, (ii) crystallization within the temperature range of the target hydrate from a saturated solution prepared at higher temperatures, (iii) crystallization within the temperature stability range from mixed solvents, and (iv) heating a higher hydrate to the temperature range of the desired lower hydrate. Analysis for water of hydration content is performed gravimetrically by gently heating the sample in a Bunsen flame. Students were able to produce results generally within 1-5% of the theoretical.

  3. Methane and carbon dioxide exchange production studies from exposed natural gas hydrate

    OpenAIRE

    Jalloh, Alusine

    2010-01-01

    Two laboratory experimental setups have been designed in collaboration with the Reservoir Physics Group at the Department of Physics and Technology. The equipments have been completed and tested. The first experiment was conducted using the four electrode resistivity measurement method on porous media. The equipment has been used to study the influence of resistance with core samples saturated with salinity concentration at 1 kHz, 1200 psig pressure and temperatures down to 3oC during stages ...

  4. HAIR LEAD CONCENTRATION IN NAKHLAK LEAD MINERS VERSUS CONTROL GROUP

    OpenAIRE

    Izadi, N.; Montazeri, K.

    2002-01-01

    Introduction. Lead poisoning is a major problem in environmental health. Exposure can occur via air, soil, food and water. Occupational exposure is the most common source of lead poisoning in adults. Lead miners are exposed to an additional source of poisoning in long term. Hair analysis may be used to evaluate chronic lead toxicity. This study compare the hair lead concentration in Nakhlak lead miners and Mohammadieh people who live 130 km far from the lead mine. Methods. Hair samples f...

  5. Relationship between sediment clay minerals and total mercury.

    Science.gov (United States)

    Kongchum, Manoch; Hudnall, Wayne H; DeLaune, R D

    2011-01-01

    A group of 262 sediment samples were collected from various lakes, rivers, reservoirs, and bayous of Louisiana. All samples were analyzed for total mercury. Twenty nine of the samples with total mercury content ranging from 11 to 401 ppb (?g/kg) were analyzed for clay minerals and other sediment physical and chemical properties. Clay content in sediments varied from 3 to 72%. Clay minerals were determined by X-ray diffraction (XRD) technique. Identification of clay minerals was determined by MacDiff software and quantification of clay minerals was obtained by Peak Height Percentage (PHP) calculation. The dominant clay mineral was Hydrated Interlayer Vermiculite (HIV), which represented 51-83% of the total clay mineral. Significant linear correlations were observed between Hg and total clay content (r=0.538**). However Smectite was the only individual clay type correlated (r=0.465**) with mercury in sediment. Cation exchange capacity (r=0.404*), organic matter (r=0.577**), and sulfur (r=0.676**) were also correlated significantly with mercury level in sediment. PMID:21469014

  6. Hydration of Acetylene: A 125th Anniversary

    Science.gov (United States)

    Ponomarev, Dmitry A.; Shevchenko, Sergey M.

    2007-01-01

    The year 2006 is the 125th anniversary of a chemical reaction, the discovery of which by Mikhail Kucherov had a profound effect on the development of industrial chemistry in the 19-20th centuries. This was the hydration of alkynes catalyzed by mercury ions that made possible industrial production of acetaldehyde from acetylene. Historical…

  7. Gas hydrate resource quantification in Uruguay

    International Nuclear Information System (INIS)

    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

  8. Dynamics of Kr in dense clathrate hydrates

    International Nuclear Information System (INIS)

    The dynamics of Kr atoms as guests in dense clathrate hydrate structures are investigated using site specific 83Kr nuclear resonant inelastic x-ray scattering (NRIXS) spectroscopy in combination with molecular dynamics simulations. The dense structure H hydrate and filled-ice structures are studied at high pressures in a diamond anvil high-pressure cell. The dynamics of Kr in the structure H clathrate hydrate quench recovered at 77 K is also investigated. The Kr phonon density of states obtained from the experimental NRIXS data are compared with molecular dynamics simulations. The temperature and pressure dependence of the phonon spectra provide details of the Kr dynamics in the clathrate hydrate cages. Comparison with the dynamics of Kr atoms in the low-pressure structure II obtained previously was made. The Lamb-Mossbauer factor obtained from NRIXS experiments and molecular dynamics calculations are in excellent agreement and are shown to yield unique information on the strength and temperature dependence of guest-host interactions.

  9. Hydration dynamics near a model protein surface

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-09-01

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

  10. Dynamics of Kr in dense clathrate hydrates

    Science.gov (United States)

    Klug, D. D.; Tse, J. S.; Zhao, J. Y.; Sturhahn, W.; Alp, E. E.; Tulk, C. A.

    2011-05-01

    The dynamics of Kr atoms as guests in dense clathrate hydrate structures are investigated using site specific Kr83 nuclear resonant inelastic x-ray scattering (NRIXS) spectroscopy in combination with molecular dynamics simulations. The dense structure H hydrate and filled-ice structures are studied at high pressures in a diamond anvil high-pressure cell. The dynamics of Kr in the structure H clathrate hydrate quench recovered at 77 K is also investigated. The Kr phonon density of states obtained from the experimental NRIXS data are compared with molecular dynamics simulations. The temperature and pressure dependence of the phonon spectra provide details of the Kr dynamics in the clathrate hydrate cages. Comparison with the dynamics of Kr atoms in the low-pressure structure II obtained previously was made. The Lamb-Mossbauer factor obtained from NRIXS experiments and molecular dynamics calculations are in excellent agreement and are shown to yield unique information on the strength and temperature dependence of guest-host interactions.

  11. Estimates of worldwide gas hydrate resources

    International Nuclear Information System (INIS)

    Gas hydrates have been touted as the next generation of energy resources exploitable for commercial gain and anthropogenic use. It would then seem relevant to estimate the potential resources available in order that one has an appreciation of availability. Several such estimates have been made over the years for both onshore and offshore gas hydrates. This paper examines the relative percentages and the ranges of uncertainty for both the onshore and offshore estimates. In addition, the estimated resources are plotted versus the year in which the estimate was made to see if any convergence of results is being achieved with time as more data become available. The main conclusions are that there seems not to be any systematic pattern of convergence of resource estimates with time, nor does there seem to be any narrowing of the uncertainty of the estimates for either onshore or offshore resource estimates as more data have become available over the last twenty years. It would seem that a concerted effort is needed to improve estimates if there is to be any hope of assessing the commercial worth of hydrate resources and of deciding whether hydrates really do represent a significant exploitable energy resource on a worldwide basis. (author)

  12. Infrared spectra of hydrated silicates, carbonaceous chondrites, and amorphous carbonates compared with interstellar dust absorptions

    International Nuclear Information System (INIS)

    Infrared (2.5 30 ?m) spectra of C1 and C2 carbonaceous chondrites have been obtained for mineral identification and comparison with interstellar dust. The spectra of carbonaceous chondrites are similar, but not identical, to serpentines, montmorillonites, and chamosites. Features at 2.7, 2.9, and 6 ?m are due to hydroxyl groups or bound water absorptions in the silicate matrix. These bands do not change significantly in shape or position at temperatures between 15 and 300 K. We discuss interstellar infrared absorption spectra using carbonaceous chondrites as a likely analogue of the interstellar material. Absorption bands at 2.7 and near 2.9 ?m could be used to test for a hydrated silicate component in the interstellar dust although such bands have not yet been unambiguously detected in astronomical observations. The interstellar 3.07 ?m band is shown not to be absorption by water or hydroxyl bound in a hydrated silicate, but a broad feature between 3.1 and 4?m in hydrated silicates resembles a feature observed in grain spectra. A band at 7 ?m in carbonaceous chondrites is probably a carbonate absorption. To study order-disorder effects on the infrared spectra of carbonates, amorphous calcite was produced and its spectrum compared with that of crystalline carbonates. We discuss the possibility that carbonates contribute to an interstellar absorption near 6.9 ?m. (orig.)

  13. The exposed breast

    International Nuclear Information System (INIS)

    The skin and lungs are two tissues that are frequently bombarded with cancer-initiating factors, such as ultraviolet rays from the sun and smoke and pollutants in the air we breathe. Yet breast cancer is the most common type of cancer in Australian women, affecting one in eight before the age of 85. It is more common than skin melanoma and lung cancer. Why, then, does the breast so commonly get cancer when it is not a tissue that is particularly exposed to the environmental agents that increase cancer risk in other major organs? Is there something unique about this tissue that makes it particularly susceptible? The breast undergoes cellular changes over the course of the monthly menstrual cycle, and and these changes affect cancer susceptibility. Rising levels of the hormones oestrogen and progesterone occur immediately after the egg is released from the ovary, and these hormones cause the breast cells to divide and change to accommodate further development if pregnancy occurs. If the woman becomes pregnant, the cells in the breast continue to develop and become the milk-producing structures required to feed a newborn baby. But if pregnancy does not occur there is a drop in progesterone, which triggers the death of the newly developed breast cells. This occurs at the same time women have their period. Then the cycle starts again, and continues every month until menopause, unless the woman becomes pregnant.

  14. Exposing the Programming Process

    DEFF Research Database (Denmark)

    Caspersen, Michael Edelgaard; Bennedsen, Jens

    2008-01-01

    One of the most important goals of an introductory programming course is that the students learn a systematic approach to the development of computer programs. Revealing the programming process is an important part of this. However, textbooks do not address the issue —probably because the textbook medium is static and, therefore, ill-suited to expose the process of programming. We have found that process recordings in the form of captured, narrated programming sessions are a simple, cheap, and efficient way of providing the revelation. We identify seven different elements of the programming process for which process recordings are a valuable communication media in order to enhance the learning process. Student feedback indicates both high learning outcome and superior learning potential compared to traditional classroom teaching. This chapter is based on Bennedsen, J. and Caspersen, M. E. 2005. Revealing the programming process. In Proceedings of the 36th SIGCSE Technical Symposium on Computer Science Education, St. Louis, Missouri, USA, February 23-27, 2005, pp. 186-190.

  15. In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea1[C][W

    Science.gov (United States)

    Wang, Peng; Menzies, Neal W.; Lombi, Enzo; McKenna, Brigid A.; de Jonge, Martin D.; Paterson, David J.; Howard, Daryl L.; Glover, Chris J.; James, Simon; Kappen, Peter; Johannessen, Bernt; Kopittke, Peter M.

    2013-01-01

    The speciation and spatial distribution of selenium (Se) in hydrated plant tissues is not well understood. Using synchrotron-based x-ray absorption spectroscopy and x-ray fluorescence microscopy (two-dimensional scanning [and associated mathematical model] and computed tomography), the speciation and distribution of toxic Se were examined within hydrated roots of cowpea (Vigna unguiculata) exposed to either 20 µm selenite or selenate. Based upon bulk solution concentrations, selenate was 9-fold more toxic to the roots than selenite, most likely due to increased accumulation of organoselenium (e.g. selenomethionine) in selenate-treated roots. Specifically, uptake of selenate (probably by sulfate transporters) occurred at a much higher rate than for selenite (apparently by both passive diffusion and phosphate transporters), with bulk root tissue Se concentrations approximately 18-fold higher in the selenate treatment. Although the proportion of Se converted to organic forms was higher for selenite (100%) than for selenate (26%), the absolute concentration of organoselenium was actually approximately 5-fold higher for selenate-treated roots. In addition, the longitudinal and radial distribution of Se in roots differed markedly: the highest tissue concentrations were in the endodermis and cortex approximately 4 mm or more behind the apex when exposed to selenate but in the meristem (approximately 1 mm from the apex) when exposed to selenite. The examination of the distribution and speciation of Se in hydrated roots provides valuable data in understanding Se uptake, transport, and toxicity. PMID:23835408

  16. Cruise report for a seismic investigation of gas hydrates in the Mississippi Canyon region, northern Gulf of Mexico; cruise M1-98-GM

    Science.gov (United States)

    Cooper, Alan K.; Hart, Patrick E.; Pecher, Ingo

    1998-01-01

    During June 1998, the U.S. Geological Survey (USGS) and the University of Mississippi Marine Minerals Technology Center (MMTC) conducted a 12-day cruise in the Mississippi Canyon region of the Gulf of Mexico (Fig. 1). The R/V Tommy Munro, owned by the Marine Research Institute of the University of Southern Mississippi, was chartered for the cruise. The general objective was to acquire very high resolution seismic-reflection data across of the upper and middle continental slope (200-1200-m water depths) to study the acoustic character, distribution and potential effects of gas hydrates within the shallow subsurface, extending from the sea floor down to the base of the gas-hydrate stability zone. The Gulf of Mexico is well known for hydrocarbon resources that include petroleum and related gases. Areas of the Gulf that lie in waters deeper than about 250 m potentially have conditions (e.g., pressure, temperature, near-surface gas content, etc.) that are right for the shallow-subsurface formation of the ice-like substance (gas and water) known as gas hydrate (Kvenvolden, 1993). Gas hydrates have previously been sampled in sea-floor cores and observed as massive mounds in several parts of the northern Gulf, including the Mississippi Canyon region (e.g., Anderson et al., 1992). Extensive seismic data have been recorded in the Gulf, in support of commercial drilling efforts, but few very high resolution data exist in the public domain to aid in gas-hydrate studies. Studies of long-term interest include those on the resource potential of gas hydrates, the geologic hazards associated with dissociation and formation of hydrates, and the impact, if any, of gas-hydrate dissociation on atmospheric warming (i.e., via release of methane, a "greenhouse" gas). Several very high resolution seismic systems (surface-towed, deep-towed, and sea-floor) were used during the cruise to test the feasibility of using such data for detailed structural (geometric) and stratigraphic (physical property) analyses based on the acoustic data. The cruise was conducted in two regions, on opposite flanks of the Mississippi Canyon, where gas hydrates are known and suspected from prior coring and seismic operations (e.g., Neurauter and Bryant, 1989). The regions are also characterized by thick surficial, relatively young (Pleistocene and younger) sediments. Swath-bathymetry data (Fig. 2) show extensive sea-floor faults, piercement features, and slumps—features whose development could potentially be related to gas hydrates. The specific objectives of the cruise were (a) to image the gas-hydrate stability zone across the continental margin to document bottom-simulating reflections (BSRs) and changes in geometry of the hydrate stability zone; (b) to image known hydrate features (with several seismic systems) to estimate physical properties for hydrate and non-hydrate areas; (c) to outline the shallow structures of the hydrate stability zone to ascertain their potential effects on the formation/distribution of hydrates and on stability of the sea floor; and (d) to estimate, if possible, the amounts of hydrates present in the shallow sub surface.

  17. On the hydration of monoatomic ions

    Science.gov (United States)

    Tawa, G. J.; Topol, I. A.; Burt, S. K.; Rashin, A. A.

    1999-11-01

    It is shown that an understanding of some key biological processes such as the thermodynamics of enzyme-ligand binding or the selectivity of ion-channels is ultimately dependent on an understanding of the details of ion hydration. Therefore, a model for calculating the hydration free energy of ions in aqueous solvent is presented. The model is used to first calculate the proton hydration free energy, ?Ghyd(H+), in an effort to resolve the uncertainty concerning its exact value. In the model we define ?Ghyd(H+) as the free energy change associated with the following process: ?G{H+(gas)+[H2O]n(aq)?H+[H2O]n)(aq)}, where the solvent is represented by a neutral n-water cluster embedded in a dielectric continuum and the solvated proton is represented by a protonated n-water cluster also in the continuum. All solvated species are treated as quantum mechanical solutes (B3LYP, MP2, MP4, CCSD(T)) coupled to a dielectric continuum using a self consistent reaction field (SCRF) cycle. An investigation of the behavior of ?Ghyd(H+) as the number of explicit waters of hydration is increased reveals convergence by n=4. The converged value is -262.23 kcal/mol and is independent of the ab initio method used. These results indicate that the first hydration shell of the proton is composed of at least 4 water molecules. The result strongly suggests that the proton hydration free energy is at the far lower end of the range of values obtained from the literature. The methodology is then used to calculate the hydration free energies of other ions relative to that of the proton. These include cationic forms of the alkali earth elements Li, Na, and K, and anionic forms of the halogens F, Cl, and Br. The relative ion hydration free energy is defined as ?[?Ghyd(Z±)]=G(Z±[H2O]n(aq))-G(H+[H2O]n(aq))-G(Z±(gas))-G(H+(gas))), where the solvated ions are represented by ion-water clusters coupled to a dielectric continuum using a self-consistent reaction field (SCRF) cycle. An investigation of the behavior of ?[?Ghyd(Z±)] as the number of explicit waters of hydration is increased reveals convergence by n=4. This convergence indicates that the free energy change for addition of water to a solvated proton-water complex is the same as the free energy change associated with the addition of water to a solvated Z±-water complex. This is true as long as there are four explicitly solvating waters associated with the ion. This convergence is independent of the type of monatomic ion studied and it occurs before the first hydration shell of the ions (typically ? 6) is satisfied. Structural analysis of the ion-water clusters reveals that waters within the cluster are more likely to form hydrogen bonds with themselves when clustering around anions, than when clustering around cations. This suggests that for small ion-water clusters, anions are more likely to be externally solvated than cations.

  18. Effect of pH on sealing ability of white mineral trioxide aggregate as a root-end filling material.

    Science.gov (United States)

    Saghiri, Mohammad Ali; Lotfi, Mehrdad; Saghiri, Ali Mohammad; Vosoughhosseini, Sepideh; Fatemi, Ali; Shiezadeh, Vahab; Ranjkesh, Bahram

    2008-10-01

    The aim of the present study was to evaluate microleakage of mineral trioxide aggregate (MTA) used as a root-end filling material after its exposure to a range of acidic environments during hydration. Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with white MTA in the experimental groups. In the control groups root-end cavities were not filled. Root-end fillings were exposed to acidic environments with pH values of 4.4, 5.4, 6.4, or 7.4 for 3 days in the experimental groups. Microleakage was evaluated by using bovine serum albumin. The evaluation was conducted at 24-hour intervals for 80 days. Data were analyzed by using one-way analysis of variance and a post hoc Tukey test. The earliest bovine serum albumin microleakage was observed in a pH value of 4.4 followed by pH values of 5.4, 6.4, and 7.4, respectively. There was a significantly longer time necessary for leakage to occur in samples stored in higher pH values (P < .000). PMID:18793926

  19. Oxidation-hydration weathering of uraninite: the current state-of-knowledge

    Directory of Open Access Journals (Sweden)

    Plášil J

    2014-04-01

    Full Text Available Oxidation-hydration weathering of uraninite, the most common U-bearing mineral in nature, comprises various physical and chemical processes that lead to the destruction of the fluorite-type structure of uraninite where U is present as tetravalent. This results in replacement of uraninite by weathering products containing U in hexavalent form, i.e. as uranyl ion, UO22+. The final assemblage of the weathering products, uranyl minerals, and their compositions depend on the various factors, namely the composition of the primary minerals and percolating oxidizing fluids that cause the alteration. The knowledge of such processes and stabilities of the uranium minerals is of the great interest namely due to demand for U as the energy source. During the past decade there has been substantial progress in understanding the mineralogy, crystallography and thermodynamics of uranyl minerals and thus a substantially improved understanding of the weathering processes themselves. This review aims to summarize the state-of-art of the current knowledge on uranium-related topics as well and identify some of the important questions that remain unanswered. The text is dedicated to Ji?í ?ejka on occasion of his 85th birthday anniversary. Ji?í greatly contributed not only to the spectroscopy and mineralogy of uranyl minerals, but also to the questions pertaining their origin and stability. Many important issues were addressed, even if briefly, in the pioneering book “Secondary Uranium Minerals” by ?ejka and Urbanec (1990 which has served, for a long-time, as a guide for beginning uranium mineralogists.

  20. Physically based 3D finite element model of a single mineralized collagen microfibril

    CERN Document Server

    Hambli, Ridha; 10.1016/j.jtbi.2012.02.007

    2012-01-01

    Mineralized collagen microfibrils in human bone provide its mechanical properties (stiffness, elasticity, ductility, energy dissipation and strength). However, detailed 3D finite element models describing the mechanical behaviour of the mineralized collagen microfibrils are still lacking. In the current work, we developed a 3D finite element model of the mineralized collagen microfibril that incorporates the physical 3D structural details. The model components consist of five tropocollagen molecules, mineral hydroxyapatite and intermolecular cross-links joining primarily the ends of the tropocollagen molecules. Dimension, arrangement and mechanical behaviour of the constituents are based on previously published experimental and theoretical data. Tensile load was applied to the microfibril under different conditions (hydrated and dehydrated collagen) to investigate the relationship between the structure and the mechanical behaviour of the mineralized collagen microfibril (stress-strain curve and elastic modulu...

  1. Phyllosilicate and Hydrated Sulfate Deposits in Meridiani

    Science.gov (United States)

    Wiseman, S. M.; Avidson, R. E.; Murchie, S.; Poulet, F.; Andrews-Hanna, J. C.; Morris, R. V.; Seelos, F. P.

    2008-01-01

    Several phyllosilicate and hydrated sulfate deposits in Meridiani have been mapped in detail with high resolution MRO CRISM [1] data. Previous studies have documented extensive exposures of outcrop in Meridiani (fig 1), or etched terrain (ET), that has been interpreted to be sedimentary in origin [e.g., 2,3]. These deposits have been mapped at a regional scale with OMEGA data and show enhanced hydration (1.9 m absorption) in several areas [4]. However, hydrated sulfate detections were restricted to valley exposures in northern Meridiani ET [5]. New high resolution CRISM images show that hydrated sulfates are present in several spatially isolated exposures throughout the ET (fig 1). The hydrated sulfate deposits in the valley are vertically heterogeneous with layers of mono and polyhydrated sulfates and are morphologically distinct from other areas of the ET. We are currently mapping the detailed spatial distribution of sulfates and searching for distinct geochemical horizons that may be traced back to differential ground water recharge and/or evaporative loss rates. The high resolution CRISM data has allowed us to map out several phyllosilicate deposits within the fluvially dissected Noachian cratered terrain (DCT) to the south and west of the hematite-bearing plains (Ph) and ET (fig 1). In Miyamoto crater, phyllosilicates are located within 30km of the edge of Ph, which is presumably underlain by acid sulfate deposits similar to those explored by Opportunity. The deposits within this crater may record the transition from fluvial conditions which produced and/or preserved phyllosilicates deposits to a progressively acid sulfate dominated groundwater system in which large accumulations of sulfate-rich evaporites were deposited .

  2. Hydrogen in porous tetrahydrofuran clathrate hydrate.

    Science.gov (United States)

    Mulder, Fokko M; Wagemaker, Marnix; van Eijck, Lambert; Kearley, Gordon J

    2008-06-23

    The lack of practical methods for hydrogen storage is still a major bottleneck in the realization of an energy economy based on hydrogen as energy carrier.1 Storage within solid-state clathrate hydrates,2-4 and in the clathrate hydrate of tetrahydrofuran (THF), has been recently reported.5, 6 In the latter case, stabilization by THF is claimed to reduce the operation pressure by several orders of magnitude close to room temperature. Here, we apply in situ neutron diffraction to show that-in contrast to previous reports([5, 6])-hydrogen (deuterium) occupies the small cages of the clathrate hydrate only to 30 % (at 274 K and 90.5 bar). Such a D(2) load is equivalent to 0.27 wt. % of stored H(2). In addition, we show that a surplus of D(2)O results in the formation of additional D(2)O ice Ih instead of in the production of sub-stoichiometric clathrate that is stabilized by loaded hydrogen (as was reported in ref. 6). Structure-refinement studies show that [D(8)]THF is dynamically disordered, while it fills each of the large cages of [D(8)]THF17D(2)O stoichiometrically. Our results show that the clathrate hydrate takes up hydrogen rapidly at pressures between 60 and 90 bar (at about 270 K). At temperatures above approximately 220 K, the H-storage characteristics of the clathrate hydrate have similarities with those of surface-adsorption materials, such as nanoporous zeolites and metal-organic frameworks,7, 8 but at lower temperatures, the adsorption rates slow down because of reduced D(2) diffusion between the small cages. PMID:18481338

  3. Naturotherapies Based on Minerals

    OpenAIRE

    Celso de Sousa Figueiredo Gomes

    2013-01-01

    Since the antiquity, and on an empirical basis, man has accumulated experience on the benefits and risks of minerals (such as, special clay, mud and sand) and other mineral resources (such as, salt, sea water, spring water, underground water, volcanic emissions and dust) on human health. Man and minerals are chemical systems sharing a common composition, comprising major, minor and trace chemical elements, such as, oxygen, hydrogen, carbon, sulphur, phosphor, calcium, magnesium, sodium, pota...

  4. Minerals Under the Microscope

    Science.gov (United States)

    Browning, Paul

    This website provides an easy-to-understand introduction to the basics of optical mineralogy. Topics include the polarized light microscope, mineral shape and cleavage, relief, color and pleochroism, interference colors, extinction angles, twinning, opacity, vibration directions and mineral identification. The site features short, clear descriptions accompanied by photographs and drawings. This website would be useful as a concise introduction to the use of a petrographic microscope in identifying minerals.

  5. Uranium mineralization in Slovakia

    International Nuclear Information System (INIS)

    The prospect and research of uranium mineralization started in Slovakia in the fiftieths. The first known uranium deposit was found in Novoveska Huta. The study of uranium mineralization continued in the early seventieths in the Permian rocks of the Kozie chrbty Mts. in uranium deposits Kravany, Vikartovce, Svabovce and Spissky Stiavnik. Later, the cooperation with the Uranium Survey continued in the Permian rocks of the Povazsky Inovec Mts in uranium deposits Kalnica and Selec. There was found also more extensive uranium mineralization underlying the known mineralized horizon in Novoveska Huta and other localities during the seventieths. Their research was accompanied by extensive drilling, mining and more detailed study of lithology, stratigraphy, tectonic, mineralogy and geochemistry of uranium mineralization. During the later research of Uranium Survey in the eightieths the study was renewed and new deposits were found in the Permian rocks of the eastern Slovakia. The last important U-Mo deposit was found by URANPRES in Jahodna. During 1991-1993 the mineralogical, petrological and geochemical research of U-Mo ores continued in Novoveska Huta, Matejovce nad Hornadom, Rudnany-Porac and Jahodna. The study included technological samples of U-Mo ores. There was distinguished relation between uranium and molybdenum mineralization and the difference in their distribution was characterized. Study of the rare earth elements accompanying the radioactive mineralization startnying the radioactive mineralization started in 1992. This monograph consists form the next chapters: (1) Methods used; (2) Geological settings of uranium mineralization; (3) Mineralogical characteristics of uranium mineralization; (4) Geochemical characteristics of uranium mineralization; (5) Origin of mineralization; (6) Conclusions; and References. (author)

  6. Metallic mineral deposits

    OpenAIRE

    Crow, M. J.; Leeuwen, T. M.

    2005-01-01

    This account concentrates on the the primary metallic mineral deposits and occurrences in Sumatra, in particular the recent discoveries of gold, tin and base metals. The residual and placer deposits are given less emphasis, as no significant discoveries have been made in recent years. The history of mineral exploration and discovery in Indonesia has been reviewed recently by van Leeuwen (1993, 1994), documenting the change in emphasis of mineral-based activities from western to eastern I...

  7. The 1.7- to 4.2-micron spectrum of asteroid 1 Ceres - Evidence for structural water in clay minerals

    Science.gov (United States)

    Lebofsky, L. A.; Feierberg, M. A.; Larson, H. P.; Johnson, J. R.; Tokunaga, A. T.

    1981-01-01

    A high-resolution Fourier spectrum (1.7-3.5 microns) and medium-resolution spectrophotometry (2.7-4.2 microns) were obtained for Asteroid 1 Ceres. The presence of the 3-micron absorption feature due to water of hydration was confirmed. The 3-micron feature is compared with the 3-micron bands due to water of hydration in clays and salts. It is concluded that the spectrum of Ceres shows a strong absorption at 2.7-2.8 microns due to structural OH groups in clay minerals. The dominant minerals on the surface of Ceres are therefore hydrated clay minerals structurally similar to terrestrial montmorillonites. There is also a narrow absorption feature at 3.1 microns which is attributable to a very small amount of water ice on Ceres. This is the first evidence for ice on the surface of an asteroid.

  8. Histocompatibility antigens in coal miners with pneumoconiosis

    Energy Technology Data Exchange (ETDEWEB)

    Soutar, C.A.; Coutts, I.; Parkes, W.R.; Dodi, I.A.; Gauld, S.; Castro, J.E.; Turner-Warwick, M.

    1983-02-01

    Twenty-five histocompatibility antigens have been measured in 100 coal miners with pneumoconiosis attending a pneumoconiosis medical panel and the results compared with a panel of 200 normal volunteers not exposed to dust. Chest radiographs were read independently by three readers according to the ILO U/C classification. On a combined score, 40 men were thought to have simple pneumoconiosis and 60 men complicated pneumoconiosis. The number of antigens tested and associations between antigens caused difficulties in assessing the statistical significance of differences in prevalence of antigens between groups of men. Using stringent criteria for statistical significance, no significant differences were found in antigen prevalences between miners and controls, or miners with simple or complicated pneumoconiosis. When a less stringent statistical approach was applied, three antigens appeared to have abnormal prevalences in these 100 miners by comparison with the normal volunteers. More detailed examination of these antigen prevalences in relation to radiographic category of pneumoconiosis did not provide any supportive evidence that these slight associations were of statistical or clinical significance. Reports on histocompatibility antigens in miners with pneumoconiosis are reviewed briefly and the results compared. There is no good evidence that any of the histocompatibility antigens so far tested are associated with a clinically important altered risk of simple or complicated pneumoconiosis when dust is inhaled.

  9. Noble gases and radiocarbon in natural gas hydrates

    Science.gov (United States)

    Winckler, Gisela; Aeschbach-Hertig, Werner; Holocher, Johannes; Kipfer, Rolf; Levin, Ingeborg; Poss, Christian; Rehder, Gregor; Suess, Erwin; Schlosser, Peter

    2002-05-01

    In samples of pure natural gas hydrates from Hydrate Ridge, Cascadia Margin, virtually no helium and neon components are present providing evidence that the light noble gases are not incorporated into the structure of natural methane hydrates. In contrast, the hydrates contain significant amounts of argon, krypton and xenon. These gases show a distinct fractionation pattern, with the heavier ones preferentially incorporated into the gas hydrate structure. The hydrate methane is devoid of 14C indicating that there is no contribution of a recent (14C-active) organic carbon reservoir to the hydrate carbon pool. On the basis of the ?13C and ?2H signature, it appears that microbial CO2-reduction is the dominant CH4 production pathway.

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

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong

    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

  11. 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.

  12. Rapid Gas Hydrate Formation Processes: Will They Work?

    Directory of Open Access Journals (Sweden)

    Thomas D. Brown

    2010-06-01

    Full Text Available Researchers at DOE’s National Energy Technology Laboratory (NETL have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with instrumentation to study rapid and continuous hydrate formation. The cells ranged in size from 100 mL for screening studies to proof-of-concept studies with NETL’s 15-Liter Hydrate Cell. Results from this work demonstrate that the rapid and continuous formation of methane hydrate is possible at predetermined temperatures and pressures within the stability zone of a Methane Hydrate Stability Curve (see Figure 1.

  13. International mineral economics

    International Nuclear Information System (INIS)

    International Mineral Economics provides an integrated overview of the important concepts. The treatment is interdisciplinary, drawing on the fields of economics, geology, business, and mining engineering. Part I examines the technical concepts important for understanding the geology of ore deposits, the methods of exploration and deposit evaluation, and the activities of mining and mineral processing. Part II focuses on the economic and related concepts important for understanding mineral development, the evaluation of exploration and mining projects, and mineral markets and market models. Finally, Part III reviews and traces the historical development of the policies of international organizations, the industrialized countries, and the developing countries. (orig.)

  14. Mineral Classification Exercise

    Science.gov (United States)

    Dexter Perkins

    This exercise is designed to help students think about the properties of minerals that are most useful for mineral classification and identification. Students are given a set of minerals and asked to come up with a hierarchical classification scheme (a "key") that can be used to identify different mineral species. They compare their results with the products of other groups. They test the various schemes by applying them to unknown samples. While doing this exercise, the students develop observational and interpretational skill. They also begin to think about the nature of classification systems.

  15. Clathrate-hydrate formation from a hydrocarbon gas mixture: Compositional evolution of formed hydrate during an isobaric semi-batch hydrate-forming operation

    International Nuclear Information System (INIS)

    Highlights: • Reports laboratory experiments of hydrate formation from synthetic natural gas. • Shows how hydrate composition changes during each hydrate-forming operation. • Compares the observed compositional change with thermodynamic simulations. • Shows a PXRD result indicating simultaneous formation of sI and sII hydrates. - Abstract: The clathrate hydrate formation from a model natural gas, i.e., a mixture of methane, ethane, and propane in a 90:7:3 molar ratio, under a constant pressure was experimentally investigated, focusing on the compositional evolution of hydrate crystals formed inside a gas-bubbling-type reactor during each semi-batch hydrate-forming operation. The experimental system used in this study was specially designed for obtaining several hydrate samples formed at different, arbitrarily selected stages during each hydrate-forming operation. Each hydrate sample was analyzed by a gas-chromatograph to determine the mole fractions of methane, ethane and propane encaged in the hydrate. These analyses revealed a monotonic increase in the methane fraction and decreases in the ethane and propane fractions during each operation until a quasi-steady state was established. Powder X-ray diffraction analyses showed that both structure-I and structure-II crystals were simultaneously formed during the quasi-steady period. The compositional evolution of the hydrates formed during the early stages before the quasi-steady state was reached deviated from corresponding predictions based on the thermodynamic-simulation scheme previously reported. A hypothetical explanation for the discrepancy between the experimental and simulation-based results was provided

  16. Examination of reaction products on the surface of UO2 fuel exposed to reactor coolant water during power operation

    International Nuclear Information System (INIS)

    A limited experimental programme has been performed to examine the reaction products on the surfaces of fuel fragments from a BWR fuel rod which had operated in the defective condition for about 100 days. A yellow crust which was observed mainly on the fuel surfaces directly exposed to the reactor coolant water was identified by XRD as the sub-monohydrate of schoepite, the same material which had been found previously in spent fuel corrosion tests in deionized water. Other corrosion products with varying morphology and size, also probably UO3 hydrate(s), were observed on surfaces some distance from the position of clad fracture. (authors)

  17. Pressure induced reactions amongst calcium aluminate hydrate phases

    International Nuclear Information System (INIS)

    The compressibilities of two AFm phases (straetlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-pressure X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the pressure-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the pressure-induced dehydration is the dominant mechanism especially with hygroscopic pressure medium. The Birch-Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the pressure-volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies.

  18. Quick Assessment of Potential Hydrate Promoters for Rapid Formation

    Directory of Open Access Journals (Sweden)

    Chi Y. Lo

    2012-10-01

    Full Text Available Hydrate technology has advanced to greater proportions: implementing the high latent heats as refrigerant, safe carbon capture as carbon sequestration in hydrates, purifying rare gases in hydrates, and safe efficient transport of energy using rapid hydrate formation. These account for only a small amount of the fundamental understanding of gas hydrates and the use of such a novel technology. A quick and broad analysis of novel hydrate promoters is needed to assess the potential of other promoter agents. This will improve the understanding of rapid hydrate formation and fundamental ideas related to the kinetics and formation of hydrates. There are still hundreds of other surfactants that have not been identified for rapid formation. The insurmountable endeavor deters many from trying as it can be like finding a needle in a hay stack. This almost futile endeavor of correctly identifying a surfactant as a promoter agent without doing a formation test can be accomplished with recent techniques. Using Raman and a liquid hydrocarbon (Cyclo-pentane, surfactants may shift the sample’s peak towards the hydrate peak (890 cm–1, thereby identifying it as a choice surfactant for rapid formation of hydrates. With a broad survey of surfactants, understanding fundamental science and engineering kinetics for hydrates will be easily achieved. Finding more effective and novel surfactants for hydrate formations will broaden the field of hydrates and self-assembling crystallization. As hydrate technology broadens, interdisciplinary fields can contribute expertise from surface science to spectroscopy leading to geological formations and engineering kinetics.

  19. Spectroscopic determination of gas-water interactions in clathrate hydrates

    International Nuclear Information System (INIS)

    The technique of forming clathrate hydrates by first forming the amorphous deposits of gas-water mixture and, secondly, annealing this deposit was used to form the clathrate hydrates of ethylene oxide, hydrogen sulfide and sulfur dioxide. Once the clathrate hydrate formed as a thin film on the CsI substrate, the infrared spectrum of these hydrates could be obtained. The clathrate hydrates could be irradiated with 1.7 MeV electrons to promote high proton concentrations in the clathrate hydrate lattice at low temperatures (approx.30K) where the Bjerrum defects in the lattice are not mobile. The ring breathing model of ethylene oxide in the clathrate hydrate can be assigned. It was possible to incorporate D2O into the hydrogen bonded lattice of the ethylene oxide clathrate hydrate by growing the clathrate hydrate epitaxially on a thin film of clathrate hydrate at 100 K. The half-life of the D2O molecules in the ethylene oxide clathrate hydrate was only 9 minutes at 120 K. The activation energy determined from the hopping rate constant in ethylene oxide clathrate hydrate was 4.5 +/- 1.8 Kcal/mole. Irradiation of the ethylene oxide clathrate hydrate with 1.7 MeV electrons transformed some of the ethylene oxide molecules in the cages to (a) CH2 = CH2, (b) CH2 = C = O, (c) CH3-CH2-OH, (d) CO2, and (e) CO. A steady state concentration of coupled HOD was maintained in irradiated samples of ethylene oxide clathrate hydrates at a temperature around 80 K. The enclathrated H2S molecule in the small cages had a different infrared spectrum (broad band complex centered at 2600 cm-1) from the H2S molecules which had been enclathrated in the large cages (broad band complex centered at 2550 cm-1)

  20. Chromosome analyses in persons exposed or assumedly exposed 1984

    International Nuclear Information System (INIS)

    Chromosome analyses were performed for 23 exposed or assumedly exposed persons. A total of 23,921 cells was evaluated. In 8 cases the observed aberration rate was within a range of spontaneous frequency; in 5 cases the aberration rate corresponded to a whole body dose of -2. (orig.)

  1. Mineralogical and geochemical behavior of mill tailing material produced from lead-zinc skarn mineralization, Hanover, Grant County, New Mexico, USA

    Science.gov (United States)

    Walder, I. F.; Chavez, W. X.

    1995-07-01

    Mineral extraction and processing, especially metal mining, produces crushed and milled waste; such material, exposed to weathering, poses the potential threat of environmental contamination. In this study, mill tailings from inactive Pb-Zn mines in New Mexico, southwest USA, have been examined for their potential environmental impacts by means of detailed mineralogical and geochemical characterization. The principal ore minerals remaining in the tailings material are sphalerite, chalcopyrite, and very minor galena, smithsonite, and cerrusite, accompanied by the gangue minerals pyrite, pyrrhotite, magnetite, hematite, garnet, pyroxene, quartz, and calcite. White precipitate occurring on tailings surfaces is composed of gypsum and hydrated magnesium sulfates. Pyrite is mostly unaltered or shows only micron-scale rims of oxidation (goethite/hematite) in some surface samples. This iron oxide rim on pyrite is the only indication of weathering-derived minerals found by microscopy. There are variations in element concentrations with depth that reflect primary variations through time as the tailings ponds were filled. Cadmium and Zn concentrations increase with depth and Ag and Pb are low for the uppermost core samples, while Cu, Ni, and Co concentrations are generally high for the uppermost core samples. These elemental distributions indicate that little or no leaching has taken place since emplacement of the tailings because no accumulation or enrichment of these metals is observed in Hanover tailings, even in reducing portions of tailings piles. Element concentrations of surface samples surrounding the tailings reflect underlying mineralized zones rather than tailings-derived soil contamination. We observed no successive decreasing metal concentrations in prevalent wind directions away from the tailings. Stream sediment samples from Hanover Creek have somewhat elevated Zn, Cd, and Pb concentrations in areas that receive sediments from erosion of the tailings. However, input from tributaries downstream of the ponds appears to be principal source of heavy metals in Hanover Creek. The results of this study indicate that there is low risk for groundwater heavy-metal contamination from Hanover tailings. Tailings material do not show significant geochemical oxidation/alteration or metal leaching with depth. Our studies indicate that neutralizing minerals present in the tailings are sufficient to keep the tailings material chemically stable. Geochemically, however, tailings materials are being eroded and may pose a threat to Hanover Creek via siltation.

  2. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, JØrgen Bengaard; Andersen, Morten D.

    2006-01-01

    Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the first- and second-coordination spheres of the spin nucleus under investigation while it is less sensitive to long-range order. Thus, crystalline as well as amorphous phases can be detected in a quantitative manner by solid-state NMR. In particular the structure of the calcium-silicate-hydrate (C-S-H) phase have been investigated in detail by 29Si and 27Al MAS NMR where the combination of the results for these spin-nuclei provides important information on the degree of Al-incorporation in the C-S-H structure and of the average chain lengths of tetrahedral SiO4 and AlO4 units. This presentation will illustrate the versatile applicability of solid-state NMR in studies of Portland cement hydration and of effects of various admixtures such as silica fume, metakaolin, and clay minerals. This includes kinetic studies on the consumption of alite and belite during Portland cement hydration and of structural characteristics for the C-S-H phase formed during hydration. It will be demonstrated that Al3+ and flouride guest-ions in the anhydrous and hydrated calcium silicates can be studied in detail by 27Al and 19F MAS NMR, thereby providing information on the local structure and the mechanisms for incorporation of these ions in the cement phases. The role of flouride ions is of special interest for mineralized Portland cements and it demonstrated that the location of these anions in anhydrous and hydrated Portland cements can be clarified using 19F MAS or 29Si{19F} CP/MAS NMR despite these cements contain only about 0.2 wt.% flourine. Finally, the detection and quantification of strätlingite (2CaO?Al2O3?SiO2?8H2O) in Portland cement mixtures containing metakaolin will be demonstrated.

  3. Groundwater Systematics in Hydrate Petroleum System Analysis

    Science.gov (United States)

    Max, M. D.; Johnson, A. H.

    2010-12-01

    The study of pore fluid movement in marine sediments is usually undertaken at large scales, except where more detailed but restricted studies of fluid and gas movement is important to hydrocarbon reservoir analysis. These detailed studies are focused on hydrocarbon traps in order to construct extraction models. More detailed studies of marine sediment generally are not warranted because the transport system that has concentrated the conventional hydrocarbons is of little importance to the persistence or economics of conventional hydrocarbon deposits, once they have formed, so long as reservoir pressures can be maintained. Once a conventional hydrocarbon deposit has formed, it may persist for a very long time, even if supply of hydrocarbons diminishes or ceases. Conventional hydrocarbon deposits are not dependent upon a particular set of physical-chemical surroundings whereas methane hydrate deposits are. Methane hydrate concentrations that may contain enough gas to warrant eventual extraction are similar to conventional gas concentration in two important ways. There have to be sources for the methane, and there have to be geological pathways through which the methane is transported in pore water systems. But geological traps do not generally bound marine gas hydrate concentrations; formation of hydrate may provide both reservoir and trap. Pressure and temperature and a continuous supply of dissolved methane in the groundwater is equally critical. If the concentration of dissolved methane in the pore water is high enoug. Without a high enough continuing ‘gas flux’ methane hydrate will dissolve. A geological analysis of a basin’s thermal and sedimentological attributes is part of petroleum system analysis because the conditions for hydrocarbon concentration, and the concentration process itself, can begin early in the history of a basin. Reservoirs may be found at any depth. In contrast, hydrate concentrations are confined to the GHSZ, a zone that commonly parallels the seafloor and only extends to a certain depth from place to place, and which will generally move upward with continued sediment deposition. Hydrate petroleum system analysis focuses (more or less) on existing groundwater systematics, as the longer geological history is not an aid to hydrate exploration. In the first instance, a geological model will indicate where beds of primary porosity are located and the manner in which groundwater may move within and between different strata using these pathways. Geological modeling of zones of secondary porosity may allow porous beds to access methane-rich groundwater. Then, the geological plumbing system should be described. Water sources must be tracked into the GHSZ, whether they are derived locally within compacting sediment (passive margin) or from greater distances and deeper sources (active margin). A number of general models are proposed. Exploration for hydrate concentrations will literally ‘follow the water’ from a methane rich, migrating groundwater source into the GHSZ.

  4. Life Origination Hydrate Theory (LOH-Theory) and the explanation of the biological diversification.

    Science.gov (United States)

    Ostrovskii, Victor E; Kadyshevich, Elena A

    2014-12-01

    The Life Origination Hydrate Theory (LOH-Theory) considers the life origination process as a sequence of thermodynamically caused regular and inevitable chemical transformations regulated by universal physical and chemical laws. The LOH-Theory bears on a number of experimental, thermodynamic, observation, and simulation researches. N-bases, riboses, nucleosides, and nucleotides and DNAs and RNAs are formed repeatedly within structural cavities of localizations of underground and underseabed honeycomb CH4-hydrate deposits from CH4 and nitrate and phosphate ions that diffused into the hydrate structures; proto-cells and their agglomerates originated from these DNAs and from the same minerals in the semi-liquid soup after liquation of the hydrate structures. Each localization gave rise to a multitude of different DNAs and living organisms. The species diversity is caused by the spatial and temporal repeatability of the processes of living matter origination under similar but not identical conditions, multiplicity of the DNA forms in each living matter origination event, variations in the parameters of the native medium, intraspecific variations, and interspecific variations. The contribution of the last to the species diversity is, likely, significant for prokaryotes and those eukaryotes that are only at low steps of their biological organization; however, in the light of the LOH-Theory, of available long-term paleontological investigations, and of studies of reproduction of proliferous organisms, we conclude that, in toto, the contribution of interspecific variations to the species diversity was earlier overestimated by some researchers. The reason of this overestimation is that origination of scores of «spores» of different organisms in any one event and multiple reproductions of such events in time and Earth's space were not taken into consideration. PMID:25179143

  5. Inherent mineralization of 2,6-dichlorobenzamide (BAM) in unsaturated zone and aquifers - Effect of initial concentrations and adaptation

    International Nuclear Information System (INIS)

    The dichlobenil metabolite BAM (2,6-dichlorobenzamide) is frequently detected in aquifers e.g. in Denmark despite the mother compound dichlobenil was banned here since 1997. BAM mineralization was investigated at environmentally relevant concentrations in sediment samples. Undisturbed sediment cores with known dichlobenil application were collected from topsoil to 8.5 m below surface resulting in 57 samples hereof 4 aquifer samples. Mineralization was only substantial (>10%) in the uppermost meter of the unsaturated zone. Microbial adaptation, observed as faster mineralization in pre-exposed than in pristine sediments from the same location, was only evident in sandy sediment where dichlobenil was still present, but not in clayey sediments. Higher initial concentrations (1-5000 ?g/kg) did not stimulate mineralization in pristine clayey or sandy sediments, or in pre-exposed sand. However, in pre-exposed clay mineralization was stimulated at high concentrations. Furthermore BAM was for the first time mineralized in aerobic aquifer sediments from different BAM-contaminated groundwater locations. - Highlights: ? BAM mineralized in BAM-contaminated aerobic aquifer sediments. ? In subsurface, fastest BAM mineralization in pre-exposed sandy sediments. ? Increased mineralization (adaptation) only observed in contaminated sandy sediment. ? In pristine sediments mineralization ratio increased with decreasing concentrations. - BAM mineralization in subsurface and groundlization in subsurface and groundwater was demonstrated.

  6. 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.

  7. Crown ether complexes of uranyl, neptunyl, and plutonyl: hydration differentiates inclusion versus outer coordination.

    Science.gov (United States)

    Gong, Yu; Gibson, John K

    2014-06-01

    The structures of actinyl-crown ether complexes are key to their extraction behavior in actinide partitioning. Only UO2(18C6)(2+) and NpO2(18C6)(+) (18C6 = 18-Crown-6) have been structurally characterized. We report a series of complexes of uranyl, neptunyl, and plutonyl with 18-Crown-6, 15-Crown-5 (15C5), and 12-Crown-4 (12C4) produced in the gas phase by electrospray ionization (ESI) of methanol solutions of AnO2(ClO4)2 (An = U, Np, or Pu) and crown ethers. The structures of 1:1 actinyl-crown ether complexes were deduced on the basis of their propensities to hydrate. Hydration of a coordinated metal ion requires that it be adequately exposed to allow further coordination by a water molecule; the result is that hydrates form for outer-coordination isomers but not for inclusion isomers. It is demonstrated that all the actinyl 18C6 complexes exhibit fully coordinated inclusion structures, while partially coordinated outer-coordination structures are formed with 12C4. Both inclusion and outer-coordination isomers were observed for actinyl-15C5 complexes, depending on whether they resulted from ESI or from collision-induced dissociation. Evidence for the formation of 1:2 complexes of actinyls with 15C5 and 12C4, which evidently exhibit bis-outer-coordination structures, is presented. PMID:24828467

  8. Mineral outlook for the year

    International Nuclear Information System (INIS)

    A mineral forecast has been published for the current year. Every endeavour has been made, to assess the economic climate in South Africa and to appraise the market potential for this country's mineral products abroad. The forecast of mineral export sales for precious metals, energy minerals, ferrous metals, non-ferrous metals, and non-metallic minerals is given

  9. Provenance and Paleoenvironment of Sandy Sediments Possibly Hosting Gas Hydrate in the Eastern Margin of Japan Sea

    Science.gov (United States)

    Uchida, T.; Takashima, I.; Ito, T.; Matsumoto, R.

    2010-12-01

    The MD179 project was undertaken by the Marion Dufresne aiming at recovery of deep seated gas and gas hydrate, methane induced carbonate, and deep sediments older than 300 ka in order to develop geologic model of gas hydrate accumulation and evaluate the possible environmental impact of gas hydrate for the last glacial-interglacial cycles. It has been inferred that methane forming gas hydrate and methane plumes are of thermogenic origin in the study area, which form gas hydrates as mounds, nodules, veins, pore fillings etc. in sediments below seafloor. Permeable intergranular pore systems of arenite sand, fractures, faults as well as gas chimneys may have played an important role as conduits for deep thermogenic hydrocarbon gas migration. Sediment samples below the seafloor were obtained in the Umitaka Spur, the Joetsu Channel, the Toyama Trough, the Japan Basin, the Nishi Tsugaru and the Okushiri Ridge areas by the UT09 and KY09-05 cruises in 2009 as well as this MD179 cruise. They have been mainly composed of muddy sediments with small amount of sandy sediments. Thin sandy layers are intercalated with thick muddy sediments, which are often strongly bioturbated with burrows and pellets. Those sandy sediments consist of fine- to medium-grained sand grains, and are sometimes tuffaceous. Pore-size distribution measurements and thin-section observations of fine- to very fine-grained arenite sands are undertaken, which indicate that porosities of muddy sediments are around 50 % but those of arenites range from 42 to 52 % of which mean pore sizes and permeabilities are larger than those of siltstones and mudstones. While the presence of gas hydrate in intergranular pores of arenite sands is not confirmed, the soupy occurrence in recovered sediments may strongly indicate the presence of gas hydrate filling the intergranular pore system of arenite sands. The geological modeling of the gas hydrate formation and evolution system is concerned for energy resource potential in the Japan Sea as well as the Nankai Trough areas. Although the chimney type accumulation may be dominated and is characterized by massive concentration of nodular and fracture filling hydrates, the sandy sediments hosting gas hydrate concentration filling the intergranular pore system may likely occur. Time of deposition and sedimentary environment of coarse-grained sediments, thermoluminescence (TL) dating of constituent quartz grains and grain-size distributions are analyzed. TL dating works on the principle that materials containing naturally occurring radioactive isotopes such as uranium, thorium or potassium are subject to low levels of radiation. In mineral crystals, this leads to ionization of the atoms in the host material and freed electrons may become trapped in structural defects or ‘holes’ in the mineral crystal lattice. These electrons can be released in the laboratory by heating under controlled conditions, and an emission of light occurs which is the basis of TL dating. They may provide information about the provenance of sands and the paleoenvironment when the sediments deposited. This study was performed as a part of the MH21 Research Consortium on methane hydrate in Japan.

  10. 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. Hence, it is possible to detect areas in the sediment sample where free gas is released due to hydrate dissociation and displaces the liquid phase. Combined with measurements and numerical simulation of the total two-phase fluxes from the sediment sample (see abstract Abendroth et al., this volume), the LARS experiments allow for detailed information on the dissociation process during hydrate production. Here we present the workflow and first results estimating local hydrate saturations and permeabilities during hydrate formation and the movement of liquid and gas phases during hydrate dissociation, respectively.

  11. Origin and character of gaseous hydrocarbons in the hydrate and non-hydrate charged sediments on the Norway - Svalbard margins

    Energy Technology Data Exchange (ETDEWEB)

    Vaular, Espen Nesheim

    2011-05-15

    Gas incubated in clathrate water-structures, stabilizes the hydrogen bonded substance termed gas hydrate. In the marine environment vast amount of carbon is stored as gas hydrates within the temperature and pressure zone these ice-like structures are stable. Natural gas hydrate mapping and characterization is important basic research that brings about critical knowledge concerning various topics. Natural gas hydrates is a vital part of the carbon cycle, it is a potential energy resource (and thereby a potential climate agent) and it is a potential geo-hazard. One of the goals the GANS initiative aimed at exploring, was the hydrate bearing sediment of the Norway -Svalbard margins, to investigate the character and expansion of natural gas hydrates. Part of the investigation was to define how the gas in the hydrated sediment was produced and where it came from. As a result this thesis addresses the matter of light hydrocarbon characterization and origin in two Norwegian hydrate deposits. On cruises to Vestnesa on the Svalbard margin and to Nyegga in the mid-Norwegian margin, samples of hydrate charged and non-hydrate charged sediments were obtained and analyzed. Through compositional and isotopic analyses the origin of the hydrate bound gas in the fluid escape feature G11 at Nyegga was determined. The hydrate incubated methane is microbial produced as well as parts of the hydrate bound ethane. The compositional analysis in both the Nyegga area and at the Vestnesa Ridge points at thermogenic contributions in the sediment interstitials and pore water. The two hydrate bearing margins show large differences in hydrocarbon content and microbial activity in the pockmarks investigated. The gravity cores from the penetrated pockmark at Vestnesa showed low hydrocarbon content and thus suggest ceased or periodic venting. The fluid flow escape features at Nyegga show large variety of flux rates based on ROV monitoring and headspace analysis of the sediment and pore water. The light hydrocarbon content varies largely both between the pockmarks and within a single pockmark. Laboratory experiments have been preformed to consider the carbon isotope fractionation effect of hydrate formation. The experiments display minor fractionation with contrasting fractionation effects of carbon isotopes when forming methane hydrates and structure two hydrates of methane, ethane and propane. This does not inflict with the interpretation of the isotopic signature of the hydrated deposits at Nyegga. Thus the proposed microbial carbon circulation in the free gas zone beneath the gas hydrate stability zone is withheld as the probable root of the light isotopic signature. (Author)

  12. Rocks & Mineral Solitaire

    Science.gov (United States)

    Andrea J. Catania

    This site features a solitaire game designed to help students identify rocks and minerals. The card game would be used by the students after class discussions about rock/mineral categories and classifications. Several sets of the card game, managed by the teacher, would be available for the students. The cards could be used both during and after class.

  13. Minerals of Pohorje marbles

    Directory of Open Access Journals (Sweden)

    Miha Jeršek

    2013-06-01

    Full Text Available In the Pohorje Mts, mostly outcrops of calcite marble can be found, which in places turn into dolomite marbles.The protolith carbonate rocks contained also detritical minerals, which remained unchanged or formed new mineralsduring metamorphosis. Minerals in the Pohorje marbles that can be seen as crystals with the naked eye or 10x magnifyingloupe and with binocular microscope were investigated. With the aid of Raman microspectroscopy, SEM-EDSanalysis and on the basis of morphological characteristics, the presence of 17 different minerals or group of mineralswas confirmed. The most numerous and also the most significant were, apart from calcite, tremolite, diopside, grossularand epidote. For the first time, vesuvianite and scapolite were described in the Pohorje Mts. Particularly rich, as faras crystal faces are concerned, were the crystals of quartz that contained needle-like amphiboles. Other minerals thatwell supplemented the mineral paragenesis were different minerals of mica and chlorite group, feldspars, magnetite,titanite, pyrite and graphite. The determined mineral association revealed the mineral diversity of Pohorje marbles,offering us a new challenge for the investigation of the characteristics and conditions during the origin of this noblerock, which was highly esteemed already by the Romans, while today it is regaining its value and recognisability.

  14. South Africa's strategic minerals

    International Nuclear Information System (INIS)

    South Africa is the world's fourth largest producer of non-fuel minerals and is an important exporter of a wide range of strategic metals and minerals to the West. The U.S.S.R. is largely self-sufficient in supplies of these commodities, but the U.S.A. is dependent to a varying extent on imports of most strategic minerals. Western Europe and Japan are even more dependent on foreign sources of these commodities. South Africa has a disproportionately large share of the world's reserves of many metals and minerals that are critically important to the West. The effects of a denial of mineral supplies from South Africa to the West are examined in terms of security of supplies to the West, increased prices, the bargaining position of other mineral exporters, and the establishment of powerful producer cartels. It is concluded that control over South Africa's minerals by the Communist Bloc would greatly enhance the economic and strategic bargaining position of the U.S.S.R., and that success in such a venture would lead to increasing pressure on other pro-Western mineral producers, such as Australia and Brazil

  15. Vitamins, Minerals, and Mood

    Science.gov (United States)

    Kaplan, Bonnie J.; Crawford, Susan G.; Field, Catherine J.; Simpson, J. Steven A.

    2007-01-01

    In this article, the authors explore the breadth and depth of published research linking dietary vitamins and minerals (micronutrients) to mood. Since the 1920s, there have been many studies on individual vitamins (especially B vitamins and Vitamins C, D, and E), minerals (calcium, chromium, iron, magnesium, zinc, and selenium), and vitamin-like…

  16. Lithium mineral waters

    Directory of Open Access Journals (Sweden)

    Munteanu Constantin

    2011-02-01

    Full Text Available Hydrological surveys showed that Romania basement contains a variety of balneary resources located within on the surface crust. Mineral waters are spread over more than 20% of the country at different depths, with a wide range of physical, chemical and therapeutic properties depending on their genesis.Balneary resources are represented mainly by therapeutic minerals that the physicochemical properties answer the needs of medical and prophylactic maintenance, enhancement and restoration of health, work capacity and physical and mental comfort of the individual.The surface waters arising from a natural source or updated by drilling and whose physical and chemical characteristics that may exert dynamic pharmaco-therapeutic are considered therapeutic mineral waters. Mineral waters are waters that have a variable content of salts, gas, minerals, radioactive elements, which gives them therapeutic properties. In the past, name of mineral water was attributed to all shallow or groundwater mineral water that could be used for therapeutic purposes. In recent years, mineral water that could be used for therapeutic purposes have been given the name of curative water.Lithium arouses a great scientific interest because, although his structure is so simple, easy to analyze, with chemical and physical properties well established the myriad of the effects on biological systems by influencing many cellular processes and molecular and the mechanism of action are still unclear generates a mystery that modern science attempting to decipher.

  17. Taxation of unmined minerals

    International Nuclear Information System (INIS)

    This paper reports on the Kentucky Revenue Cabinet which began implementing its controversial unmined minerals tax program. The Revenue Cabinet should complete its first annual assessment under this program in December, 1989. The Revenue Cabinet's initial efforts to collect basic data concerning the Commonwealth's coal bearing lands has yielded data coverage for 5 million of Kentucky's 10 million acres of coal lands. Approximately 1000 detailed information returns have been filed. The returns will be used to help create an undeveloped mineral reserves inventory, determine mineral ownership, and value mineral reserves. This new program is run by the Revenue Cabinet's Mineral Valuation Section, under the Division of Technical Support, Department of Property Taxation. It has been in business since September of 1988

  18. Mineral industry in Australia

    International Nuclear Information System (INIS)

    The paper reviews the history and growth of the mineral industry in Australia and its significance to the nation's economic growth and overseas trade, particularly over the last twenty years during which time production of coal, iron ore, manganese and mineral sands has increased greatly and new discoveries of petroleum, bauxite and nickel have given rise to major new industries. Australia ranks fourteenths in the value of world trade and is among the world's largest exporters of alumina, iron ore, mineral sands, coal, lead, zinc and nickel. Some details of production, processing and exports of the major minerals are given. Comment is made on the policies and roles of the six State Governments and the Federal Government in respect of ownership and control of the mining, processing and exporting of both energy and non-energy minerals. (orig.)

  19. Mineral Industry in Egypt-Part I: Metallic Mineral Commodities

    OpenAIRE

    Abouzeid, Abdel-zaher M.; Khalid, Abdel-aziz M.

    2011-01-01

    This The mineral potential in Egypt is quite high. Almost all sorts of industrial minerals such as metallic and non-metallic commodities exist in commercial amounts. However, Egypt imports many of the mineral commodities needed for the local mineral industries. The main reason for this is that the investors, either the governmental or the private sectors, refrain from investing into the mineral industry for prospecting, evaluation, and developing the mining and mineral processing technologies...

  20. Vibrational excitation induced proton transfer in hydrated nafion membranes.

    Science.gov (United States)

    Liu, Liyuan; Bakker, Huib J

    2015-02-12

    We study the energy relaxation and structural relaxation dynamics of hydrated protons in Nafion membranes at different hydration levels using femtosecond infrared transient absorption spectroscopy. At low hydration levels we observe that the excitation of the proton vibration of an Eigen-like proton hydration structure leads to a structural relaxation process in which the Eigen-like structure evolves to a Zundel-like proton hydration structure. This reorganization leads to a transfer of the proton charge and closely follows the mechanism of infrared-induced adiabatic proton transfer that has been proposed by S. Hammes-Schiffer, J. T. Hynes, and others. At high hydration levels, the spectral dynamics are dominated by vibrational energy relaxation and subsequent cooling of the proton hydration structures and the surrounding water molecules. Using a kinetic analysis of the transient spectral data, we determine the rates of proton transfer, vibrational energy relaxation, and cooling as a function of hydration level. We find that infrared-induced proton transfer occurs at all hydration levels but becomes less observable at high hydration levels due to the increasingly dominant influence of the vibrational energy relaxation. PMID:25506744

  1. Terahertz spectroscopy of concrete for evaluating the critical hydration level

    Science.gov (United States)

    Dash, Jyotirmayee; Ray, Shaumik; Nallappan, Kathirvel; Sasmal, Saptarshi; Pesala, Bala

    2014-03-01

    Concrete, a mixture of cement, coarse aggregate, sand and filler material (if any), is widely used in the construction industry. Cement, mainly composed of Tricalcium Silicate (C3S) and Dicalcium Silicate (C2S) reacts readily with water, a process known as hydration. The hydration process forms a solid material known as hardened cement paste which is mainly composed of Calcium Silicate Hydrate (C-S-H), Calcium Hydroxide and Calcium Carbonate. To quantify the critical hydration level, an accurate and fast technique is highly desired. However, in conventional XRD technique, the peaks of the constituents of anhydrated and hydrated cement cannot be resolved properly, where as Mid-infrared (MIR) spectroscopy has low penetration depth and hence cannot be used to determine the hydration level of thicker concrete samples easily. Further, MIR spectroscopy cannot be used to effectively track the formation of Calcium Hydroxide, a key by-product during the hydration process. This paper describes a promising approach to quantify the hydration dynamics of cement using Terahertz (THz) spectroscopy. This technique has been employed to track the time dependent reaction mechanism of the key constituents of cement that react with water and form the products in the hydrated cement, viz., C-S-H, Calcium Hydroxide and Calcium Carbonate. This study helps in providing an improved understanding on the hydration kinetics of cement and also to optimise the physio-mechanical characteristics of concrete.

  2. Investigation of mechanisms of gas hydrates accumulation in permafrost environments

    Science.gov (United States)

    Chuvilin, E. M.

    2012-12-01

    The feature of permafrost sediments is capability to accumulate a quantity of natural gases foremost methane with low admixture of carbon dioxide. In consequence of natural and climatic changes, formation of favorable thermobaric conditions for transformation of intra-permafrost gas accumulations from free state into gas hydrate is possible. In consideration of high gas-saturation of frozen sediments, the active processes of hydrate formation in permafrost during the transgression of arctic seas or under continental glaciations can be expected. A special experimental technique was elaborated to perform physical modeling of hydrate formation conditions in cryogenic ice-containing sediments. The experiments were carried out under constant negative temperatures in interval from -2 oC to -9 oC. Methane (99.98%) was used as hydrate-former gas. During the experiments the kinetics of gas consumption in porous media was investigated and also part of porous water turned into hydrate and hydrate- saturation of sediment samples were estimated. Experiments show that hydrate formation in gas saturated sediments occurs actively not only in freezing sediments (above 0 oC) but also in frozen sediments (below 0 oC). Intensity of hydrate formation in frozen sediments depends on such factors as ice-saturation, thermobaric conditions and gas composition. Experimental data shows that after attenuation of hydrate formation in frozen sediments the considerable activization of hydrate accumulation processes during the increasing of temperature above 0 oC can occur. That leads to the thawing of porous ice, which does not turn into hydrate, and attendant this process structural-textural changes result in appearance of new gas-water contacts. As a result there is second hydrate formation on background of thawing of ice. Based on analysis of geological data and experimental researches possible geological models of gas hydrates formation in shallow permafrost under the sea transgression and under continental glaciations were presented.

  3. Mineral distribution and dimensional changes in human dentin during demineralization.

    Science.gov (United States)

    Kinney, J H; Balooch, M; Haupt, D L; Marshall, S J; Marshall, G W

    1995-05-01

    Many bonding agents require the dentin surface to be acid-etched prior to being bonded. Understanding the stability and morphology of the etched dentin surface is important for improving bond strength and reliability in these systems. In this study, the atomic force microscope was used to quantify dimensional changes that occur to fully hydrated dentin during demineralization with a pH 4.0 lactic acid gel. A high-resolution microtomography instrument, the x-ray tomographic microscope, was also used to quantify the mineral density distribution in the dentin as a function of etching time. The intertubular dentin surface shrank by less than 0.5 microns during etching, while the peritubular dentin receded at an initially rapid linear rate. The dentin surface retained its initial morphology, although it was more porous with the removal of the peritubular dentin. Beneath the etched surface, there were three major zones characterized by mineral density differences. The first zone was a fully demineralized collagen layer, subjacent to which was a partially demineralized zone of roughly constant mineral density. Immediately following the partially mineralized layer was normal dentin. The presence of the partially mineralized layer could be explained in terms of different transport rates in the peritubular and intertubular dentin. PMID:7790595

  4. A comparative study of the modelling of cement hydration and cement-rock laboratory experiments

    International Nuclear Information System (INIS)

    Highlights: ? A modelling intercomparison has shown that the dominant reaction pathways are well understood. ? However, significant differences in model parameterisation produced similar results. ? The modelling showed that there is benefit in keeping the numerical models as simple as possible. - Abstract: The use of cement and concrete as fracture grouting or as tunnel seals in a geological disposal facility for radioactive wastes creates potential issues concerning chemical reactivity. From a long-term safety perspective, it is desirable to be able model these interactions and changes quantitatively. The 'Long-term Cement Studies' (LCS) project was formulated with an emphasis on in situ field experiments with more realistic boundary conditions and longer time scales compared with former experiments. As part of the project programme, a modelling inter-comparison has been conducted, involving the modelling of two experiments describing cement hydration on one hand and cement-rock reaction on the other, with teams representing the NDA (UK), Posiva (Finland), and JAEA (Japan). This modelling exercise showed that the dominant reaction pathways in the two experiments are fairly well understood and are consistent between the different modelling teams, although significant differences existed amongst the precise parameterisation (e.g. reactive surface areas, dependences of rate upon pH, types of secondary minerals), and in some instances, processes (e.g. partition of ances, processes (e.g. partition of alkali elements between solids and liquid during cement hydration; kinetic models of cement hydration). It was not conclusive if certain processes such as surface complexation (preferred by some modellers, but not by others) played a role in the cement-rock experiment or not. These processes appear to be more relevant at early times in the experiment and the evolution at longer timescales was not affected. The observed permeability profile with time could not be matched. The fact that no secondary minerals could be observed and that the precipitated mass calculated during the simulations is minor might suggest that the permeability reduction does not have a chemical origin, although a small amount of precipitates at pore throats could have a large impact on permeability. The modelling exercises showed that there is an interest in keeping the numerical models as simple as possible and trying to obtain a reasonable fit with a minimum of processes, minerals and parameters. However, up-scaling processes and model parameterisation to the timescales appropriate to repository safety assessment are of considerable concern. Future modelling exercises of this type should focus on a suitable natural or industrial analogue that might aid assessing mineral-fluid reactions at these longer timescales.

  5. A comparative study of the modelling of cement hydration and cement-rock laboratory experiments

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David, E-mail: savaged@me.com [Quintessa Ltd., The Hub, 14 Station Road, Henley-on-Thames, RG9 1AY (United Kingdom); Soler, Josep M. [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Yamaguchi, Kohei; Walker, Colin; Honda, Akira; Inagaki, Manabu [Japan Atomic Energy Agency (JAEA), Tokai-mura, Naka-gun, Ibaraki-ken 319-1194 (Japan); Watson, Claire; Wilson, James; Benbow, Steven [Quintessa Ltd., The Hub, 14 Station Road, Henley-on-Thames, RG9 1AY (United Kingdom); Gaus, Irina; Rueedi, Joerg [Nagra, Hardstrasse 73, Wettingen CH-5430 (Switzerland)

    2011-07-15

    Highlights: > A modelling intercomparison has shown that the dominant reaction pathways are well understood. > However, significant differences in model parameterisation produced similar results. > The modelling showed that there is benefit in keeping the numerical models as simple as possible. - Abstract: The use of cement and concrete as fracture grouting or as tunnel seals in a geological disposal facility for radioactive wastes creates potential issues concerning chemical reactivity. From a long-term safety perspective, it is desirable to be able model these interactions and changes quantitatively. The 'Long-term Cement Studies' (LCS) project was formulated with an emphasis on in situ field experiments with more realistic boundary conditions and longer time scales compared with former experiments. As part of the project programme, a modelling inter-comparison has been conducted, involving the modelling of two experiments describing cement hydration on one hand and cement-rock reaction on the other, with teams representing the NDA (UK), Posiva (Finland), and JAEA (Japan). This modelling exercise showed that the dominant reaction pathways in the two experiments are fairly well understood and are consistent between the different modelling teams, although significant differences existed amongst the precise parameterisation (e.g. reactive surface areas, dependences of rate upon pH, types of secondary minerals), and in some instances, processes (e.g. partition of alkali elements between solids and liquid during cement hydration; kinetic models of cement hydration). It was not conclusive if certain processes such as surface complexation (preferred by some modellers, but not by others) played a role in the cement-rock experiment or not. These processes appear to be more relevant at early times in the experiment and the evolution at longer timescales was not affected. The observed permeability profile with time could not be matched. The fact that no secondary minerals could be observed and that the precipitated mass calculated during the simulations is minor might suggest that the permeability reduction does not have a chemical origin, although a small amount of precipitates at pore throats could have a large impact on permeability. The modelling exercises showed that there is an interest in keeping the numerical models as simple as possible and trying to obtain a reasonable fit with a minimum of processes, minerals and parameters. However, up-scaling processes and model parameterisation to the timescales appropriate to repository safety assessment are of considerable concern. Future modelling exercises of this type should focus on a suitable natural or industrial analogue that might aid assessing mineral-fluid reactions at these longer timescales.

  6. Incoherent inelastic neutron scattering of clathrate hydrates

    International Nuclear Information System (INIS)

    We measured incoherent inelastic neutron scattering of clathrate hydrates of carbon dioxide, xenon and tetrahydrofuran in order to investigate the effect of the motion of guest molecule on the surrounding hydrogen-bonded network. The results showed that the peak of the transverse acoustic mode of the host water in the clathrate hydrates is stronger than that in the ice Ih. Furthermore, the intensity of the peak depends on the type of the guest molecule. The enhancement of the peak is attributed to the coupling of the translational vibration of the guest molecule and the lattice vibration of the host water, since these vibration modes are in the same energy region. It is concluded that the interaction between the guest molecules and the host waters is so strong that the coupling of the vibrations of the guest molecules and the host lattice depends on the type of guest molecule. (author)

  7. A statistical mechanical description of biomolecular hydration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    We present an efficient and accurate theoretical description of the structural hydration of biological macromolecules. The hydration of molecules of almost arbitrary size (tRNA, antibody-antigen complexes, photosynthetic reaction centre) can be studied in solution and in the crystal environment. The biomolecular structure obtained from x-ray crystallography, NMR, or modeling is required as input information. The structural arrangement of water molecules near a biomolecular surface is represented by the local water density analogous to the corresponding electron density in an x-ray diffraction experiment. The water-density distribution is approximated in terms of two- and three-particle correlation functions of solute atoms with water using a potentials-of-mean-force expansion.

  8. Silicate anion structural change in calcium silicate hydrate gel on dissolution of hydrated cement

    International Nuclear Information System (INIS)

    High pH conditions of aqueous solutions in a radioactive waste repository can be brought about by dissolution of cementitious materials. In order to clarify the mechanisms involved in maintaining this high pH for long time, we investigated the dissolution phenomena of OPC hydrate. In the present research, leaching tests on powdered cement hydrates were conducted by changing the ratio of mass of leaching water to mass of OPC hydrate (liquid/solid ratio) from 10 - 2,000 (wt/wt). Ordinary Portland Cement hydrate was contacted with deionized water and placed in a sealed bottle. After a predetermined period, the solid was separated from the solution. From the results of XRD analysis on the solid phase and the Ca concentration in the aqueous phase, it was confirmed that Ca(OH)2 was preferentially dissolved when the liquid/solid ratio was 10 or 100 (wt/wt), and that C-S-H gel as well as Ca(OH)2 were dissolved when the liquid/solid ratio was 500 (wt/wt) or larger. 29Si-NMR results showed that the silicate anion chain of the C-S-H gel became longer when the liquid/solid ratio was 500 (wt/wt) or greater. This indicates that leaching of OPC hydrate results in a structural change of C-S-H gel. (author)

  9. Silicate anion structural change in calcium silicate hydrate gel on dissolution of hydrated cement

    Energy Technology Data Exchange (ETDEWEB)

    Haga, Kazuko; Shibata, Masahito [Taiheiyo Consultant Co., Ltd., Sakura, Chiba (Japan); Hironaga, Michihiko [Central Research Institute of Electric Power Industry, Abiko, Chiba (Japan); Tanaka, Satoru [Tokyo Univ., Department of Quantum Engineering and Systems Sciences, Tokyo (Japan); Nagasaki, Shinya [Tokyo Univ., Graduate School of Frontier Sciences, Institute of Environmental Studies, Tokyo (Japan)

    2002-05-01

    High pH conditions of aqueous solutions in a radioactive waste repository can be brought about by dissolution of cementitious materials. In order to clarify the mechanisms involved in maintaining this high pH for long time, we investigated the dissolution phenomena of OPC hydrate. In the present research, leaching tests on powdered cement hydrates were conducted by changing the ratio of mass of leaching water to mass of OPC hydrate (liquid/solid ratio) from 10 - 2,000 (wt/wt). Ordinary Portland Cement hydrate was contacted with deionized water and placed in a sealed bottle. After a predetermined period, the solid was separated from the solution. From the results of XRD analysis on the solid phase and the Ca concentration in the aqueous phase, it was confirmed that Ca(OH){sub 2} was preferentially dissolved when the liquid/solid ratio was 10 or 100 (wt/wt), and that C-S-H gel as well as Ca(OH){sub 2} were dissolved when the liquid/solid ratio was 500 (wt/wt) or larger. {sup 29}Si-NMR results showed that the silicate anion chain of the C-S-H gel became longer when the liquid/solid ratio was 500 (wt/wt) or greater. This indicates that leaching of OPC hydrate results in a structural change of C-S-H gel. (author)

  10. Mineralization of CCl4 and CCl2F2 on solid surfaces

    International Nuclear Information System (INIS)

    The mineralization of 14CCl4 and 14CCl2F2 in the dark is shown to be greatly dependent on the nature of the solid surfaces to which they are exposed, alumina being more effective than silica gel and a number of natural sands. Activation of the solids by drying or mechanically by tumbling leads to increased mineralization rates. (orig.)

  11. Mesostructure from hydration gradients in demosponge biosilica.

    Science.gov (United States)

    Neilson, James R; George, Nathan C; Murr, Meredith M; Seshadri, Ram; Morse, Daniel E

    2014-04-22

    Organisms of the phylum Porifera, that is, sponges, utilize enzymatic hydrolysis to concatenate bioavailable inorganic silicon to produce lightweight, strong, and often flexible skeletal elements called spicules. In their optical transparency, these remarkable biomaterials resemble fused silica, despite having been formed under ambient marine biological conditions. Although previous studies have elucidated the chemical mechanisms of spicule formation and revealed the extensive hydration of these glasses, their precise composition and local and medium-range structures had not been determined. We have employed a combination of compositional analysis, (1) H and (29) Si solid-state nuclear magnetic resonance spectroscopy, and synchrotron X-ray total scattering to characterize spicule-derived silica produced by the demosponge Tethya aurantia. These studies indicate that the materials are highly hydrated, but in an inhomogeneous manner. The spicule-derived silica is, on average, perfectly dense for the given extent of hydration and regions of fully condensed and unstrained Si?O networks persist throughout each monolithic spicule. To accommodate chemical strain and defects, the extensive hydration is concentrated in distinct regions that give rise to mesostructural features. The chemistry responsible for producing spicule silica resembles hydrolytic sol-gel processing, which offers exceptional control over the precise local atomic arrangement of materials. However, the specific processing involved in forming the sponge spicule silica further results in regions of fully condensed silica coexisting with regions of incomplete condensation. This mesostructure suggests a mechanism for atomistic defect tolerance and strain relief that may account for the unusual mechanical properties of the biogenic spicules. PMID:24633700

  12. Agent-based modelling for cement hydration

    OpenAIRE

    Va?zquez Gallo, Mari?a Jesu?s; Cerro Prada, Mari?a Elena; Alonso Trigueros, Jesu?s Mari?a; Romera Zarza, Andre?s Luis

    2012-01-01

    The Agent-Based Modelling and simulation (ABM) is a rather new approach for studying complex systems withinteracting autonomous agents that has lately undergone great growth in various fields such as biology, physics, social science, economics and business. Efforts to model and simulate the highly complex cement hydration process have been made over the past 40 years, with the aim of predicting the performance of concrete and designing innovative and enhanced cementitious materials. The ABM ...

  13. Life Origination Hydrate Hypothesis (LOH-Hypothesis)

    OpenAIRE

    Victor Ostrovskii; Elena Kadyshevich

    2012-01-01

    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 cavi...

  14. Competitive hydrated positron reactions with halides

    International Nuclear Information System (INIS)

    The hydrated positron, esub(aq)sup(+), reactions with halides and pseudohalides were studied by angular correlation technique. At halide concentrations below 0.02 M, the reaction of esub(aq)sup(+) with halides, x-, to form bound states [x-,e+] is diffusion controlled. On adding two halides to water containing a Ps inhibitor, the first positron transfer rate constants could be determined. For example, the reaction [Br-,e+] + I- ? Br- + [I-,e+] was studied. (Auth.)

  15. Serrano charged up for hydrates battle

    Energy Technology Data Exchange (ETDEWEB)

    Flatern, R. von

    2001-07-01

    The plugging of pipelines by paraffin and hydrate formations is an obstacle still to be overcome in the transportation of gases in deep cold water. However, a new flow assurance technique is soon to be installed in Shell's Serrano and Oregano fields in the Gulf of Mexico and this is expected to eventually impact on the entire offshore industry: it is this development which is discussed. The system uses electricity to heat the pipelines.

  16. Science of NFL Football: Nutrition, Hydration & Health

    Science.gov (United States)

    NBC Learn

    2010-10-07

    NBC's Lester Holt looks at the physically demanding pre-season ritual of NFL training camp. Douglas Casa, head of the Korey Stringer Institute at the University of Connecticut, and athletic trainers from the Pittsburgh Steelers explain what NFL players must do to stay hydrated and replenish the essential nutrients needed to maintain good health during rigorous practices. "Science of NFL Football" is a 10-part video series funded by the National Science Foundation and produced in partnership with the National Football League.

  17. Hydration and mobility of HO-(aq)

    International Nuclear Information System (INIS)

    The hydroxide anion plays an essential role in many chemical and biochemical reactions. But questions of its hydration state and transport in water are currently controversial. Here we address this situation using the quasi-chemical theory of solutions. The simplest such approach suggests that HO (H20)3- is the most probable species at infinite dilution in aqueous solution under standard conditions, followed by the HO . (H20)2- and HO . (HzO)- forms which are close together in stablity. HO . (H20)4- is less stable, in contrast to recent proposals that the latter structure is the most stable hydration species in solution. Ab initio molecular dynamics results presented here support the dominance of the tri-hydrated form, but that the population distribution is broad and sensitive to solution conditions. On the basis of these results, the mobility of hydroxide can be simply that of a proton hole. This contrasts with recent proposals invoking the interconversion of a stable 'trap' structure HO . (H20)4- to HO . (H20)3- as the rate determining step in the transport process.

  18. Predicting hydration energies for multivalent ions.

    Science.gov (United States)

    Andersson, Martin P; Stipp, Susan L S

    2014-10-30

    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 absolute predictions of hydration energies but could be used to investigate trends for several ions, thanks to the low computational cost, in particular for ligand exchange reactions. PMID:25212881

  19. The economics of exploiting gas hydrates

    International Nuclear Information System (INIS)

    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

  20. Hydration energies of protonated and sodiated thiouracils.

    Science.gov (United States)

    Wincel, Henryk

    2014-12-01

    Hydration reactions of protonated and sodiated thiouracils (2-thiouracil, 6-methyl-2-thiouracil, and 4-thiouracil) generated by electrospray ionization have been studied in a gas phase at 10 mbar using a pulsed ion-beam high-pressure mass spectrometer. The thermochemical data, ?H(o)n, ?S(o)n, and ?G(o)n, for the hydrated systems were obtained by equilibrium measurements. The water binding energies of protonated thiouracils, [2SU]H(+) and [6Me2SU]H(+), were found to be of the order of 51 kJ/mol for the first, and 46 kJ/mol for the second water molecule. For [4SU]H(+), these values are 3-4 kJ/mol lower. For sodiated complexes, these energies are similar for all studied systems, and varied between 62 and 68 kJ/mol for the first and between 48 and 51 kJ/mol for the second water molecule. The structural aspects of the precursors for hydrated complexes are discussed in conjunction with available literature data. PMID:25270881

  1. Combinatorial molecular optimization of cement hydrates

    Science.gov (United States)

    Abdolhosseini Qomi, M. J.; Krakowiak, K. J.; Bauchy, M.; Stewart, K. L.; Shahsavari, R.; Jagannathan, D.; Brommer, D. B.; Baronnet, A.; Buehler, M. J.; Yip, S.; Ulm, F.-J.; van Vliet, K. J.; Pellenq, R. J.-. M.

    2014-09-01

    Despite its ubiquitous presence in the built environment, concrete’s molecular-level properties are only recently being explored using experimental and simulation studies. Increasing societal concerns about concrete’s environmental footprint have provided strong motivation to develop new concrete with greater specific stiffness or strength (for structures with less material). Herein, a combinatorial approach is described to optimize properties of cement hydrates. The method entails screening a computationally generated database of atomic structures of calcium-silicate-hydrate, the binding phase of concrete, against a set of three defect attributes: calcium-to-silicon ratio as compositional index and two correlation distances describing medium-range silicon-oxygen and calcium-oxygen environments. Although structural and mechanical properties correlate well with calcium-to-silicon ratio, the cross-correlation between all three defect attributes reveals an indentation modulus-to-hardness ratio extremum, analogous to identifying optimum network connectivity in glass rheology. We also comment on implications of the present findings for a novel route to optimize the nanoscale mechanical properties of cement hydrate.

  2. Propane hydrate nucleation: Experimental investigation and correlation

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj

    2008-01-01

    In this work the nucleation kinetics of propane gas hydrate has been investigated experimentally using a stirred batch reactor. The experiments have been performed isothermally recording the pressure as a function of time. Experiments were conducted at different stirring rates, but in the same 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. Theresults 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 of induction times according to the model is likely to be due to a change in the nuclei-substrate contact angle.

  3. 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 absolute predictions of hydration energies but could be used to investigate trends for several ions, thanks to the low computational cost, in particular for ligand exchange reactions.

  4. Hydration Energies of Protonated and Sodiated Thiouracils

    Science.gov (United States)

    Wincel, Henryk

    2014-12-01

    Hydration reactions of protonated and sodiated thiouracils (2-thiouracil, 6-methyl-2-thiouracil, and 4-thiouracil) generated by electrospray ionization have been studied in a gas phase at 10 mbar using a pulsed ion-beam high-pressure mass spectrometer. The thermochemical data, ?H o n, ?S o n, and ?G o n, for the hydrated systems were obtained by equilibrium measurements. The water binding energies of protonated thiouracils, [2SU]H+ and [6Me2SU]H+, were found to be of the order of 51 kJ/mol for the first, and 46 kJ/mol for the second water molecule. For [4SU]H+, these values are 3-4 kJ/mol lower. For sodiated complexes, these energies are similar for all studied systems, and varied between 62 and 68 kJ/mol for the first and between 48 and 51 kJ/mol for the second water molecule. The structural aspects of the precursors for hydrated complexes are discussed in conjunction with available literature data.

  5. Assessment radiation risks deposits non-radioactive mineral

    International Nuclear Information System (INIS)

    The detail radiation survey fulfill on the mining deposits of non-radioactive minerals. The survey establishes the presence of local radiometric anomalies in the rocks exposed by mine personal. It was also found increased levels of volumetric radioactivity of air exceeding the level of intervention. These data confirm the need for detailed radiation surveys of underground deposits of non-radioactive material complexes.

  6. Characterization of potential mineralization in Afghanistan: four permissive areas identified using imaging spectroscopy data

    Science.gov (United States)

    King, Trude V.V.; Berger, Byron R.; Johnson, Michaela R.

    2014-01-01

    As part of the U.S. Geological Survey and Department of Defense Task Force for Business and Stability Operations natural resources revitalization activities in Afghanistan, four permissive areas for mineralization, Bamyan 1, Farah 1, Ghazni 1, and Ghazni 2, have been identified using imaging spectroscopy data. To support economic development, the areas of potential mineralization were selected on the occurrence of selected mineral assemblages mapped using the HyMap™ data (kaolinite, jarosite, hydrated silica, chlorite, epidote, iron-bearing carbonate, buddingtonite, dickite, and alunite) that may be indicative of past mineralization processes in areas with limited or no previous mineral resource studies. Approximately 30 sites were initially determined to be candidates for areas of potential mineralization. Additional criteria and material used to refine the selection and prioritization process included existing geologic maps, Landsat Thematic Mapper data, and published literature. The HyMapTM data were interpreted in the context of the regional geologic and tectonic setting and used the presence of alteration mineral assemblages to identify areas with the potential for undiscovered mineral resources. Further field-sampling, mapping, and supporting geochemical analyses are necessary to fully substantiate and verify the specific deposit types in the four areas of potential mineralization.

  7. The use of electrical impedance spectroscopy for monitoring the hydration products of Portland cement mortars with high percentage of pozzolans

    International Nuclear Information System (INIS)

    In this paper, mortars and pastes containing large replacement of pozzolan were studied by mechanical strength, thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mercury intrusion porosimetry (MIP) and electrical impedance spectroscopy (EIS). The effect of metakaolin (35%) and fly ash (60%) was evaluated and compared with an inert mineral addition (andalusite). The portlandite content was measured, finding that the pozzolanic reaction produced cementing systems with all portlandite fixed. The EIS measurements were analyzed by the equivalent electrical circuit (EEC) method. An EEC with three branches in parallel was applied. The dc resistance was related to the degree of hydration and allowed us to characterize plain and blended mortars. A constant phase element (CPE) quantified the electrical properties of the hydration products located in the solid–solution interface and was useful to distinguish the role of inert and pozzolanic admixtures present in the cement matrix

  8. The use of electrical impedance spectroscopy for monitoring the hydration products of Portland cement mortars with high percentage of pozzolans

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, J.M. [Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera, 46022, Valencia (Spain); Fita, I.C., E-mail: infifer@fis.upv.es [Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera, 46022, Valencia (Spain); Soriano, L.; Payá, J.; Borrachero, M.V. [ICITECH, Instituto de Ciencia y Tecnología del Hormigón, Universitat Politècnica de València (Spain)

    2013-08-15

    In this paper, mortars and pastes containing large replacement of pozzolan were studied by mechanical strength, thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mercury intrusion porosimetry (MIP) and electrical impedance spectroscopy (EIS). The effect of metakaolin (35%) and fly ash (60%) was evaluated and compared with an inert mineral addition (andalusite). The portlandite content was measured, finding that the pozzolanic reaction produced cementing systems with all portlandite fixed. The EIS measurements were analyzed by the equivalent electrical circuit (EEC) method. An EEC with three branches in parallel was applied. The dc resistance was related to the degree of hydration and allowed us to characterize plain and blended mortars. A constant phase element (CPE) quantified the electrical properties of the hydration products located in the solid–solution interface and was useful to distinguish the role of inert and pozzolanic admixtures present in the cement matrix.

  9. Time-resolved monitoring of cement hydration: Influence of cellulose ethers on hydration kinetics

    International Nuclear Information System (INIS)

    Brilliant synchrotron radiation combined with a new micro-strip detector enables fast in situ measurements at the Materials Sciences beamline of the Swiss Light Source SLS at the Paul Scherrer Institut. Early hydration processes of Portland cement and the retarding effect of cellulose ether (CE) were monitored with a time resolution of 10 s. Cellulose ethers inhibit cement hydration in a phase- and CE-specific manner. The degree of substitution (DS), a major parameter of CE-characterization, is the most relevant factor whereas other characteristics such as molecular weight (MW) and CE-chemistry play minor roles in terms of retardation. The lower the DS the stronger the retardation of C2S/C3S-hydration

  10. Detection and context of hydrated mineralogy in the Tyrrhena Terra region, Mars

    Science.gov (United States)

    den Haan, J.; Zegers, T. E.; van Ruitenbeek, F. J. A.; van der Werff, H. M. A.; Rossi, A.

    2008-09-01

    Introduction The discovery of phyllosilicates on Mars [1] has had major implications on the perceived geologic and climatologic evolution of Mars [2]. Not only do phyllosilicates represent a `wet' period on Mars, they might also represent a potentially favorable environment for life. The phyllosilicates have so far exclusively been found in or close to ancient Noachian highland terrain. Those phyllosilicate deposits studied (e.g. [3]) show a clear association between hydrated mineralogy and heavily eroded and crater-saturated outcrops. Phyllosilicates on Earth are associated with a wide variety of geological processes (volcanism, metamorphism, hydrothermal alteration, sedimentation). The occurrence of phyllosilicates on Mars may be equally diverse in nature. To be able to place constraints on the early Martian environment, the processes by which these phyllosilicates formed need to be reconstructed. To derive this information from individual phyllosilicate deposits, it is necessary to interpret their composition in relation to their geological context and relative time relationships. We conducted such an integrated hyperspectral and geological study of the Tyrrhena Terra region. Data products ad methods HRSC data products (both image at 12 m/pixel and stereo-derived DTMs) are used for examining geologic cross-cutting relationships, geomorphologic landforms and visual determination of unit boundaries. Odyssey THEMIS nighttime TIR images are analyzed for spatial variations in thermal inertia. Where available, HRSC is supplemented by higher-resolution visible observations of CTX or MOC. Hyperspectral analysis is conducted using data from the OMEGA hyperspectral instrument. In order to batch-process large amounts of OMEGA data, an IDL/ENVI tool was developed on top of the existing SOFT04, distributed by PSA. The applied atmospheric correction assumes that atmospheric contributions are multiplicative, and follow a power-law distribution with altitude [4]. The ratio of two spectra taken at base and summit of Olympus Mons provides the atmospheric spectrum. To quickly assess the mineralogy of a large region, CRISM multispectral summary products [5] are applied to OMEGA datasets. Hydrated mineral deposits are located on the basis of the absorption feature centered at ~1.9um. This feature is the result of a combination of v2 bend and v3 (asymmetrical) stretch mode overtones. Noise reduction is performed by applying a principal component transform to the OMEGA data. Principal components which are dominated by noise are manually selected and discarded, after which the data are transformed back to the wavelength domain. Using this approach, a large degree of system noise can be effectively eliminated without significantly affecting signal quality [6]. Results The methods described have led to positive identification of large deposits of hydrated mineralogy in Tyrrhena Terra. Whilst several deposits are evidently associated with cratering processes (e.g. [7]), one major deposit in particular draws attention (figure 1). In this deposit, the light-colored hydrated minerals are generally associated with very rough morphology. In addition, they seem to be located underneath a dark, crater-saturated unit. Given the limited quality of local OMEGA-derived spectra, it is impossible to unambiguously determine the exact mineralogy of the deposit. The hydrated signature is correlated with high night-time temperatures as observed in THEMIS IRnight observations (figure 2). This indicates the hydrated material is present as a solid bedrock mass (e.g. mudstone) instead of a loose concretion. The deposit is situated in a topographic low, bounded by a channel-rich unit in the north and a sharp unit contact in the south. Discussion The sharp unit contact south of the hydrated deposit coincides with a sharp contrast in topographic elevation. It strikes parallel to the contours of Isidis Planitia, a trend which is continued on larger scale. Given the strike and morphological characteristics, this contact is likely a normal fault, which was created as a d

  11. Dissolution mechanisms of CO2 hydrate droplets in deep seawaters

    International Nuclear Information System (INIS)

    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

  12. Experimental Simulation of the Exploitation of Natural Gas Hydrate

    Directory of Open Access Journals (Sweden)

    Chang-Yu Sun

    2012-02-01

    Full Text Available Natural gas hydrates are cage-like crystalline compounds in which a large amount of methane is trapped within a crystal structure of water, forming solids at low temperature and high pressure. Natural gas hydrates are widely distributed in permafrost regions and offshore. It is estimated that the worldwide amounts of methane bound in gas hydrates are total twice the amount of carbon to be found in all known fossil fuels on earth. A proper understanding of the relevant exploitation technologies is then important for natural gas production applications. In this paper, the recent advances on the experimental simulation of natural gas hydrate exploitation using the major hydrate production technologies are summarized. In addition, the current situation of the industrial exploitation of natural gas hydrate is introduced, which are expected to be useful for establishing more safe and efficient gas production technologies.

  13. Development of Alaskan gas hydrate resources. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  14. Experimental Determination of Refractive Index of Gas Hydrates

    DEFF Research Database (Denmark)

    Bylov, Martin; Rasmussen, Peter

    1997-01-01

    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. 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 to be unaffected by the history of the water. (C) 1997 Elsevier Science Ltd.

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

    Science.gov (United States)

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

    2012-08-01

    Recently, hydrogen storage using clathrate hydrate as a medium has become a hotspot of hydrogen storage research In the present paper, the laser Raman spectroscopy was used to study the hydrogen storage in nitrogen hydrate. The synthetic nitrogen hydrate was reacted with hydrogen gas under relatively mild conditions (e.g., 15 MPa, -18 degrees C). The Raman spectra of the reaction products show that the hydrogen molecules have enclathrated the cavities of the nitrogen hydrate, with multiple hydrogen cage occupancies in the clathrate cavities. The reaction time is an important factor affecting the hydrogen storage in nitrogen hydrate. The experimental results suggest that nitrogen hydrates are expected to be an effective media for hydrogen storage. PMID:23156768

  16. Nucleation of gas hydrates within constant energy systems.

    Science.gov (United States)

    Liang, Shuai; Kusalik, Peter G

    2013-02-01

    The early stage of formation of gas hydrates has recently attracted attention as amorphous intermediate gas hydrate structures have been observed, apparently contrary to a classical model of nucleation and some experimental observations. To date, essentially all reported molecular simulations of the nucleation of gas hydrates have been under constant temperature conditions, which does not consider the possible impacts of heat transfer on the nucleation processes. Here we show, using constant energy molecular simulations, that the nuclei at an early stage of the hydrate formation have relatively more crystalline order in comparison with those observed in previous isothermal (NPT or NVT) work. The current work suggests a more transient role for intermediate amorphous structures during hydrate nucleation, thereby providing a stronger link between molecular simulation and experimental observations. Our NVE results nevertheless support the two-step nucleation mechanism proposed in previous simulation studies under constant temperature conditions which features the initial formation of amorphous hydrate-like structures. PMID:23330680

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

    International Nuclear Information System (INIS)

    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

  18. Welding tritium exposed stainless steel

    International Nuclear Information System (INIS)

    Stainless steels that are exposed to tritium become unweldable by conventional methods due to buildup of decay helium within the metal matrix. With longer service lives expected for tritium containment systems, methods for welding on tritium exposed material will become important for repair or modification of the systems. Solid-state resistance welding and low-penetration overlay welding have been shown to mitigate helium embrittlement cracking in tritium exposed 304 stainless steel. These processes can also be used on stainless steel containing helium from neutron irradiation, such as occurs in nuclear reactors

  19. Effects of hydration on laser soldering

    Science.gov (United States)

    Chan, Eric K.; Brown, Dennis T.; Kovach, Ian S.; Welch, Ashley J.

    1997-05-01

    Laser welding with albumin-based tissue solder has been investigated as an alternative to surgical suturing. Many surgical procedures require the soldered tissues to be in a hydrated environment. We have studied the effects of hydration on laser soldered rat dermis and baboon articular cartilage in vitro. The solder is composed of human serum albumin, sodium hyaluronate and indocyanine green. We used a micro-pipette to deposit 2 (mu) l of solder on each tissue specimen. An 808 nm cw laser beam with irradiance of 27 W/cm2 was scanned 4 times over the same solder area at a constant speed of 0.84 mm/sec. After photo-coagulation, each tissue specimen was cut into two halves at the center of the solder, perpendicular to the direction of the scanning laser beam. One half was reserved as control while the other half was soaked in phosphate buffered saline for a designated hydration period. The hydration periods were 1 hr, 1, 2, and 7 days. All tissue specimens were fixed in glutaraldahyde, then prepared for scanning electron microcopy analysis. For most of the specimens, there was non-uniform coagulation across the thickness of the solder. Closer to the laser beam, the upper solder region formed a more dense coagulum. While the region closer to solder-tissue interface, the solder aggregated into small globules. This non-uniform coagulation was likely caused by non-uniform energy distribution during photocoagulation. The protein globules and coagulum seem to be responsible for the solder attachment from the specimen surface. However, we have noted that the solder detached from the cartilage substrate as early as after 1 hr of hydration. On the other hand, the solder attached to the dermis much better than to cartilage. This may be explained by the difference in surface roughness of the two tissue types. The dermal layer of the skin is composed of collagen matrix which may provide a better entrapment of the solder than the smooth surface of articular cartilage.

  20. Mineral resource of the month: natural and synthetic zeolites

    Science.gov (United States)

    Virta, R.

    2008-01-01

    Robert Virta, mineral commodity specialist for the U.S. Geological Survey, prepared the following information about the zeolite industry. Volcanic rocks containing natural zeolites — hydrated aluminosilicate minerals that contain alkaline and alkaline-earth metals — have been mined worldwide for more than 1,000 years for use as cements and building stone. For centuries, people thought natural zeolites occurred only in small amounts inside cavities of volcanic rock. But in the 1950s and early 1960s, large zeolite deposits were discovered in volcanic tuffs in the western United States and in marine tuffs in Italy and Japan. And since then, similar deposits have been found around the world, from Hungary to Cuba to New Zealand. The discovery of these larger deposits made commercial mining of natural zeolite possible.

  1. Characterization of clay minerals

    International Nuclear Information System (INIS)

    The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

  2. Ion-water clusters, bulk medium effects, and ion hydration

    OpenAIRE

    Merchant, Safir; Dixit, Purushottam D.; Dean, Kelsey R.; Asthagiri, D.

    2011-01-01

    Thermochemistry of gas-phase ion-water clusters together with estimates of the hydration free energy of the clusters and the water ligands are used to calculate the hydration free energy of the ion. Often the hydration calculations use a continuum model of the solvent. The primitive quasichemical approximation to the quasichemical theory provides a transparent framework to anchor such efforts. Here we evaluate the approximations inherent in the primitive quasichemical approa...

  3. Effect of POM on Formation Kinetics of Methane Hydrate

    OpenAIRE

    Malik, S. N. A.; Sabil, K. M.; Mutalib, M. I. A.

    2014-01-01

    The kinetics of formation of methane hydrate in deionised water in presence of Potassium Oxalate Monohydrate (POM) is studied in a batch reactor which is designed and built for a laboratory scale used. In this experimental study, the formation of methane hydrate in deionised water (18?) is investigated at fixed temperature of 273.15 K and pressures of 65, 60, 55, 50, 40 bar, respectively. The formation of methane hydrates in POM solutions are investigated by using various concentrations of P...

  4. A molecular dynamics study on sI hydrogen hydrate.

    Science.gov (United States)

    Mondal, S; Ghosh, S; Chattaraj, P K

    2013-07-01

    A molecular dynamics simulation is carried out to explore the possibility of using sI clathrate hydrate as hydrogen storage material. Metastable hydrogen hydrate structures are generated using the LAMMPS software. Different binding energies and radial distribution functions provide important insights into the behavior of the various types of hydrogen and oxygen atoms present in the system. Clathrate hydrate cages become more stable in the presence of guest molecules like hydrogen. PMID:23093389

  5. Effect of gas hydrates melting on seafloor slope instability

    OpenAIRE

    Sultan, Nabil; Cochonat, Pierre; Foucher, Jean-paul; Mienert, J.

    2004-01-01

    We present a theoretical study of the thermodynamic chemical equilibrium of gas hydrate in soil by taking into account the influence of temperature, pressure, pore water chemistry, and the mean pore size distribution. The model uses a new formulation based on the enthalpy form of the law of conservation of energy. The developed model shows that due to a temperature and pressure increase, hydrates may dissociate at the top of the hydrate occurrence zone to ensure a chemical equilibrium with th...

  6. Distribution of Hydrate Inhibitors in Processing of Gas-Condensate

    OpenAIRE

    Jonassen, Anette Hartveit

    2013-01-01

    The formation of gas hydrates have been known to cause serious problems with blockages in natural gas pipelines, wellbore and natural gas processing units. The offshore sector of the North Sea comes into focus owing to factors such as low temperature, high pressure because of deep water fields, great depth of the subsea environment and remote locations that are factors underlying the increased hydrate formation. Hydrates are formed in multiphase transport comprising gas, condensate and water....

  7. Natural Gas Hydrates - from the Microstructure towards a Geological Understanding

    OpenAIRE

    Klapp, Stephan A.

    2009-01-01

    The dissertation addresses mineralogical characteristics of natural gas hydrates from cold seeps in the Gulf of Mexico and the eastern Black Sea. The investigated properties are the crystal structure, the crystallite sizes and size distributions, the compositions of the hydrate-forming gases, the hydrate porosity as well as the grain boundary networks. That was accomplished using X-ray diffraction, gas chromatography, Raman-spectroscopy, and scanning electron microscopy. "Bragg tomography" wa...

  8. Experimental Simulation of the Exploitation of Natural Gas Hydrate

    OpenAIRE

    Chang-Yu Sun; Guang-Jin Chen; Ben-Cheng Wu; Xin Yang; Ke-Hua Su; Qing Yuan; Bei Liu

    2012-01-01

    Natural gas hydrates are cage-like crystalline compounds in which a large amount of methane is trapped within a crystal structure of water, forming solids at low temperature and high pressure. Natural gas hydrates are widely distributed in permafrost regions and offshore. It is estimated that the worldwide amounts of methane bound in gas hydrates are total twice the amount of carbon to be found in all known fossil fuels on earth. A proper understanding of the relevant exploitation technologie...

  9. Can gas hydrate structures be described using classical simulations?

    OpenAIRE

    Conde, M. M.; Vega, C.; Mcbride, C.; Noya, E. G.; Ramirez, R.; Sese, L. M.

    2010-01-01

    Quantum path-integral simulations of the gas hydrate solids have been performed using the recently proposed TIP4PQ/2005 model. By also performing classical simulations using this model, the impact of the nuclear quantum effects on the hydrates is highlighted; nuclear quantum effects significantly modify the structure, densities and energies of the gas hydrates, leading to the conclusion that nuclear quantum effects are important not only when studying the solid phases of water but also when s...

  10. Influence of PC superplasticizers on tricalcium silicate hydration.

    OpenAIRE

    Pourchet, S.; Comparet, C.; Nicoleau, L.; Nonat, A.

    2007-01-01

    The influence of polycarboxylate superplasticizers with variations of content of anionic groups was studied on pure tricalcium silicate hydration. The hydration in diluted suspension has been investigated by conductimetry, calorimetry, and ionic and total organic carbon analysis of the liquid phase. The tricalcium silicate hydration is always delayed in presence of polycarboxylate superplasticizer. Moreover, the delay can be correlated with the number of carboxylate groups which are on the ad...

  11. Rapid Gas Hydrate Formation Processes: Will They Work?

    OpenAIRE

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

    2010-01-01

    Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with in...

  12. Gel hydration: obstruction effect in self-diffusion

    International Nuclear Information System (INIS)

    The extent of hydration of agar was calculated from the self-diffusion studies of Brsup(-) and Isup(-) ions in agar gel medium. The measured obstruction effect caused by these macromolecules is related to the extent of hydration by Wang's equation. The value of hydration expressed in terms of grams of bound water per gram of anhydrous agar, in presence of NaI and NHsub(4)Br(0.1M) electrolytes comes out to be about 5.2. (author)

  13. Hydrated-ion molecule reactions: temperature dependence as a function of hydration number

    International Nuclear Information System (INIS)

    Rate constants have been measured using the Selected Ion Flow Tube (SIFT) technique over the temperature range 200 - 500K for the selectively hydrated reactant OH-.(H2O) with hydrogen halides and methyl halides. The former are representative proton transfer reactions and the latter representative displacement reactions, each of which show different temperature dependences for unhydrated reactants: dk/ dT = O and dk/dT < O respectively. For both categories, the temperature dependence of most reaction rate constants is not changed significantly by hydration of the reactant ion

  14. Characterization of CO2 hydrate formation by temperature vibration

    International Nuclear Information System (INIS)

    Research highlights: ? A method of temperature vibration is proposed to improve CO2 hydrate formation. ? Temperature vibration is effective for CO2 hydrate formation with pure water. ? By temperature vibration, the gas consumption can be increased 1.6 times with SDS. ? Appropriate operation time enables short hydrate formation period. -- Abstract: A method of temperature vibration was proposed to promote CO2 hydrate formation based on the dual nature of CO2 solubility in hydrate-forming regions. The effects on carbon dioxide hydrate formation were investigated in a small scale reactor. The results show that the hydrate formation with distilled water in a quiescent system can be improved effectively by temperature vibration, and the pressure drop is increased by 30%. The effect is especially evident with 0.3% sodium dodecyl sulfate (SDS) additive using temperature vibration method, and large amount of hydrates are formed. The rest gas pressure is very close to the phase equilibrium value at setting temperature. Moreover, the pressure drop of CO2 gas in the reactor is about 2.6 times of that without temperature vibration. With appropriate operation time of temperature vibration, hydrate formation period can be greatly shortened.

  15. Synergistic kinetic inhibition of natural gas hydrate formation

    DEFF Research Database (Denmark)

    Daraboina, Nagu; Malmos, Christine

    2013-01-01

    Rocking cells were used to investigate the natural gas hydrate formation and decomposition in the presence of kinetic inhibitor, Luvicap. In addition, the influence of poly ethylene oxide (PEO) and NaCl on the performance of Luvicap was investigated using temperature ramping and isothermal experiments. Luvicap decreased the hydrate nucleation temperature in ramping and increased the hydrate nucleation time at fixed temperatures. The presence of PEO and NaCl enhanced the nucleation inhibition strength of Luvicap. However the addition of Luvicap promoted the hydrate growth after nucleation. PEO does not affect hydrate growth whereas NaCl reduced the hydrate growth both in the presence and absence of Luvicap. In addition complex two-stage hydrate growth was observed in the presence of Luvicap. Moreover, the hydrate formed in the presence of inhibitor took longer time/higher temperature to decompose completely. One should consider this complex inhibitor-mediated hydrate formation and decomposition kinetics when screening and designing kinetic inhibitors for field applications.

  16. Hydrate control for WAG injection in the Ekofisk field

    Energy Technology Data Exchange (ETDEWEB)

    Lekvam, Knut; Surguchev, Leonid M.; Ekrann, Steinar; Svartaas, Thor Martin; Kelland, Malcolm; Nilsson, Svante; Oevsthus, Jorun; Gjoevikli, Nils B.

    1997-12-31

    The report relates to a hydrate formation project for the Ekofisk field on the Norwegian continental shelf. To remove the possible hydrate formation problems during WAG (Water Alternating Gas) treatment, the following project was conducted to estimate roughly the distance from the injection well that hydrate formation can be prevented by whatever treatment is most appropriate. The first aim was to test experimentally whether selected kinetic hydrate inhibitors could be used, and in which concentrations and quantities. In addition evaluations were done to calculate the required volume of the inhibitor solutions that have to be injected to prevent mixing of uninhibited water and gas. 8 figs., 8 tabs.

  17. Impact of welan gum on tricalcium aluminate-gypsum hydration

    Energy Technology Data Exchange (ETDEWEB)

    Ma Lei, E-mail: malei198713@163.com; Zhao Qinglin, E-mail: zhaoqinglin@whut.edu.cn; Yao Chukang; Zhou Mingkai

    2012-02-15

    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{sub 3}A was also demonstrated. Thus, through the adsorption effect, welan gum induces a retarding behavior in tricalcium aluminate-gypsum hydration. Highlights: Black-Right-Pointing-Pointer Adsorption characteristics of welan gum on C{sub 3}A and ettringite have been studied. Black-Right-Pointing-Pointer C{sub 3}A-gypsum hydration behavior and the hydration products are examined in L/S = 3. Black-Right-Pointing-Pointer Welan gum retards the process of C{sub 3}A-gypsum hydration. Black-Right-Pointing-Pointer The addition of welan gum changes the nucleation growth of ettringite.

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

    International Nuclear Information System (INIS)

    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 C3A 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 C3A and ettringite have been studied. ? C3A–gypsum hydration behavior and the hydration products are examined in L/S = 3. ? Welan gum retards the process of C3A–gypsum hydration. ? The addition of welan gum changes the nucleation es the nucleation growth of ettringite.

  19. The sensitivity of seismic responses to gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Foley, J.E.; Burns, D.R.

    1992-06-01

    The primary goal of this project was to determine the sensitivity of seismic responses to gas hydrate and associated free gas saturation within marine sediments. The development of a model to predict the physical properties of sediments containing hydrates was required. This model was used as the basis for predicting the sensitivity of P and S wave seismic velocities and waveform amplitudes to variations in hydrate and free gas saturation. Secondary goals of the project included: assessment of the usefulness of seismic shear waves in characterizing hydrate saturation and a review of potential complications in seismic modeling procedures.

  20. The sensitivity of seismic responses to gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Foley, J.E.; Burns, D.R.

    1992-01-01

    The primary goal of this project was to determine the sensitivity of seismic responses to gas hydrate and associated free gas saturation within marine sediments. The development of a model to predict the physical properties of sediments containing hydrates was required. This model was used as the basis for predicting the sensitivity of P and S wave seismic velocities and waveform amplitudes to variations in hydrate and free gas saturation. Secondary goals of the project included: assessment of the usefulness of seismic shear waves in characterizing hydrate saturation and a review of potential complications in seismic modeling procedures.

  1. Molecular dynamics simulations for selection of kinetic hydrate inhibitors.

    Science.gov (United States)

    Kvamme, Bjørn; Kuznetsova, Tatyana; Aasoldsen, Kjetil

    2005-06-01

    Natural gas hydrates are ice-like structures composed of water and gas molecules that have long been a problem in petroleum industry. Heavy cost of alcohol and glycol injection has spurred an interest in called 'kinetic inhibitors' able to slow down the hydrate formation rather than prevent it. Since it is not possible to compare directly the macroscopic effects of different inhibitors on the kinetics of hydrate formation in computer experiments, a scheme capable of culling the list of candidates for experimental testing was proposed earlier [B. Kvamme, G. Huseby, O.K. Førrisdahl, Molecular dynamics simulations of PVP kinetic inhibitor in liquid water and hydrate/liquid water systems, Mol. Phys. 90 (1997) 979-991]. Molecular dynamics simulations were implemented to test several kinetic inhibitors in a multiphase water-hydrate system with rigid hydrate interface. In addition, a long-scale run was implemented for a system where the hydrate was free to melt and reform. Our conclusion that PVCap will outperform PVP as a kinetic hydrate inhibitor is supported by experimental data. We demonstrate that numerical experiments can be a valuable tool for selecting kinetic inhibitors as well as provide insight into mechanisms of kinetic inhibition and hydrate melting and reformation. PMID:15908248

  2. Rate of Hydrate Inhibitor in Long Subsea Pipelines

    OpenAIRE

    Christiansen, Ha?kon Eidem

    2012-01-01

    This thesis is divided into several parts. The first part deals with hydrate theory and where hydrates form in the gas-and oil-dominated systems. A review of how hydrate plugs is formed and a method for removing hydrate plugs safely is also included.Simplified HYSYS models of the upstream part of Ormen Lange and Snøhvit gas fields on the Norwegian Continental Shelf constituted the basis for answering the second part of the task. Data from private conversations, reports, slide presentatio...

  3. Geomechanical constitutive modelling of gas-hydrate-bearing sediments

    OpenAIRE

    Sultan, Nabil; Garziglia, Sebastien

    2011-01-01

    In this work and in order to consider theoretically the effect of gas hydrates on the mechanical properties of their host sediments, hydrate fraction was introduced as a state variable in the framework of a Critical State model. For the proposed model, the process of de-structuration and softening of natural clay was considered as a proxy for the gas-hydrate-bearing-sediments behaviour. The developed constitutive model seemed to reproduce the main key behaviours of gas-hydrate-bearing sands o...

  4. Method for the photocatalytic conversion of gas hydrates

    Science.gov (United States)

    Taylor, Charles E. (Pittsburg, PA); Noceti, Richard P. (Pittsburg, PA); Bockrath, Bradley C. (Bethel Park, PA)

    2001-01-01

    A method for converting methane hydrates to methanol, as well as hydrogen, through exposure to light. The process includes conversion of methane hydrates by light where a radical initiator has been added, and may be modified to include the conversion of methane hydrates with light where a photocatalyst doped by a suitable metal and an electron transfer agent to produce methanol and hydrogen. The present invention operates at temperatures below 0.degree. C., and allows for the direct conversion of methane contained within the hydrate in situ.

  5. 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 then used TOUGH + Hydrate to simulate the observed gas production and reservoir pressure field data at Messoyakha. We simulated various scenarios that help to explain the field behavior. We have evaluated the effect of reservoir parameters on gas recovery from hydrates. Our work should be beneficial to others who are investigating how to produce gas from a hydrate capped gas reservoir. The results also can be used to better evaluate the process of producing gas from offshore hydrates. The Schlumberger PETREL model is used in industry to the description of geologic horizons and the special distribution of properties. An interface between FLAC3D and Petrel was built by Schlumberger to allow for efficient data entry into TOUGH + Hydrate + FLAC3D.

  6. Oxygen isotope fractionation between hydration water and free water in the MgSO4 and FeSO4 systems

    Science.gov (United States)

    Kohl, I. E.; Coleman, M. L.

    2012-12-01

    Hydrated MgSO4 and FeSO4 minerals are thought to exist on the surface of Mars. The role of water during the early history of Mars is a hotly debated topic with implications in almost all aspects of planetary science. Specifically, water is often discussed with respect to sedimentary (evaporitic and clastic) rocks and potential microbiology. In the laboratory, we can measure the isotope composition of crystalline water liberated from hydrated minerals. We are not so far from being able to make these same measurements via the SAM instrument suite on MSL, given an appropriate precision is achieved for water isotope ratio measurements. However, when these measurements are made, what will they actually tell us? Is crystalline water scavenged directly from an existing (aqueous) hydration sphere? If so, what is the relationship between the hydration sphere water and the bulk water's mean isotopic composition? What are the most important variables in these types of systems? Some information exists on the difference between crystalline water and solution water for a select few hydrated mineral species. However, these experiments and natural studies were not conducted under a wide variety of conditions (temperature, molarity, and humidity). Existing work indicates that equilibrium humidity, which is dependent on temperature and solution concentration, effects isotopic fractionation between liquid water and water vapor. The above variables have also been identified as determining the isotopic exchange rates and therefore, control the time it takes for a given solution-vapor system to reach isotopic equilibrium. The isotopic fractionation that occurs between liquid and vapor water is only one component of a complex system. Other aspects of the water-crystalline water systems associated with evaporite deposits are even less well understood. This study focused on the isotopic behavior occurring during hydration sphere formation in solutions containing variable concentrations of MgSO4 or FeSO4. The isotope composition of free (non-hydration sphere) waters from experimental solutions were determined by replicate analyses of CO2 gas equilibrated with 18MOhm water containing 0-2.0M MgSO4 and 0-1.6M FeSO4 (the highest concentrations were just below saturation). Differences over the temperature range, 4°C - 70°C were measured between pure water and free water from ionic solutions showed maximum ?18O (difference between measured CO2 from a given solution and that from pure water) at the highest temperatures and concentrations, of -6‰ and -3‰ for MgSO4 and FeSO4, respectively. ?18O were, for the most part, linear with both concentration and temperature, decreasing to <1‰ at 0.5 -0.2M. The changes in free water isotopic composition reflect fractionation associated with the capture of hydration sphere water and ion pair formation. As different ion pair types have different hydration numbers and are likely to have slightly different fractionation factors, these data will eventually allow us to compute the isotopic compositions of all species in the system. The main target being hydration sphere water and a validation that, as expected, this latter water is captured as crystalline water during formation of hydrated evaporite minerals. These data will enable the understanding of possible bulk water isotopic compositions on Mars.

  7. Alteration of cement hydrate by dissolution. 2. Modeling a cement alteration by coupling dissolution of hydrates and mass transport

    Energy Technology Data Exchange (ETDEWEB)

    Toyohara, Masumitsu; Kaneko, Masaaki; Nakada, Koutaro; Ueda, Hiroaki [Toshiba Corp., Power Systems and Services Company, Power and Industrial Systems Research and Development Center, Yokohama, Kanagawa (Japan); Haga, Kazuko [Taiheiyo Consultant Co., Ltd., Environ. Mater. Dept., Tokyo (Japan); Nogiwa, Hisao [Toshiba Engineering Corp., Kawasaki, Kanagawa (Japan)

    2002-06-01

    A model has been developed for prediction of pore water chemistries and solid constituents of cement, in order to study the cement degradation process caused by dissolution of hydrates. The dissolution models of portlandite, hydrated calcium-silicate gels and other hydrates, which are the main hydrates in cement, are introduced into the geochemical code to couple with the one-dimensional advective-dispersion transport model. The pH and the chemical concentrations in pore water, and the distributions of pore volume and elements in solid are studied by using this coupled code. The calculated results agree with the permeability test results for hardened cement. By using calculated results of distributions of elements, hydrates and pore volume in solid, the dissolution process in which the hydrated cement is altered by its own dissolution is discussed. (author)

  8. Mutagenesis of Bacteria by Fibrous or Clay Minerals

    Directory of Open Access Journals (Sweden)

    Naoto Yoshida

    2004-01-01

    Full Text Available In the present cells of Escherichia coli, Agrobacterium radiobacter, or Thiobacillus intermedius were exposed to chrysotile asbestos, kaolinite, or bentonite by culture in medium containing these minerals. Chromosomal DNA was extracted from exposed cells, then amplified by the RAPD method and band patterns were compared. DNA of bacterial cells exposed to these minerals, was amplified, in whereas that in control cells was not, or that amplified in control cells disappeared. Not only asbestos, but also kaolinite and bentonite, which are principal soil components, induce bacterial mutation. Growth was inhibited by 66%, when A. radiobacter was cultured in LB medium containing 20 mg mL-1 of asbestos for 24 h. Growth inhibition by asbestos was reduced by adding 420 U mL-1 of catalase or 500 U mL-1 of superoxide dismutase to the culture medium.