WorldWideScience
1

Clinker mineral hydration at reduced relative humidities  

DEFF Research Database (Denmark)

Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6), hydrogarnet. (C) 1999 Elsevier Science Ltd. All rights reserved.

Jensen, Ole Mejlhede; Hansen, Per Freiesleben

1999-01-01

2

CO2 adhesion on hydrated mineral surfaces.  

Science.gov (United States)

Hydrated mineral surfaces in the environment are generally hydrophilic but in certain cases can strongly adhere CO2, which is largely nonpolar. This adhesion can significantly alter the wettability characteristics of the mineral surface and consequently influence capillary/residual trapping and other multiphase flow processes in porous media. Here, the conditions influencing adhesion between CO2 and homogeneous mineral surfaces were studied using static pendant contact angle measurements and captive advancing/receding tests. The prevalence of adhesion was sensitive to both surface roughness and aqueous chemistry. Adhesion was most widely observed on phlogopite mica, silica, and calcite surfaces with roughness on the order of ~10 nm. The incidence of adhesion increased with ionic strength and CO2 partial pressure. Adhesion was very rarely observed on surfaces equilibrated with brines containing strong acid or base. In advancing/receding contact angle measurements, adhesion could increase the contact angle by a factor of 3. These results support an emerging understanding of adhesion of, nonpolar nonaqueous phase fluids on mineral surfaces influenced by the properties of the electrical double layer in the aqueous phase film and surface functional groups between the mineral and CO2. PMID:24040744

Wang, Shibo; Tao, Zhiyuan; Persily, Sara M; Clarens, Andres F

2013-10-15

3

Water molecules in clay minerals: Thermodynamic functions and hydration  

Science.gov (United States)

Thermodynamic functions and adsorption of water molecules are very important properties for clay minerals. Smectite MX-80 and mixed-layer illite-smectite ISCz-1 were selected. They were first carefully characterized (HRTEM with EDX analysis), revealing original results. Then, the thermodynamic properties of water in clay were obtained by (i) comparison of the thermodynamic properties of anhydrous and hydrated minerals, between 0 and 350 K (adiabatic calorimetry, solution isothermal calorimetry), and (ii) water vapor adsorption isotherms, between 300 and 380 K (magnetic suspension thermobalance). Solution isothermal calorimetry is used to determine the enthalpies of formation of the minerals (1 bar and 298 K). Comparison of the results, for the anhydrous and the hydrated minerals, leads to the enthalpies of hydration at 298 K. Adiabatic calorimetry measurements give the heat capacities of the minerals from 5 to 350 K. Entropies, enthalpies of formation and Gibbs free energies of formation, for the anhydrous and the hydrated minerals, and then, entropies of hydration, enthalpies of hydration and Gibbs free energies of hydration, between 0 and 350 K, are finally obtained. Comparison of two close hydration states leads to the entropy, the enthalpy and the Gibbs free energy of the adsorption reaction: H2O free - H2O adsorbed. The Cp(T) curve, for the heat capacity of water in clay - i.e., the difference between the heat capacities of the hydrated and the anhydrous minerals -, shows that water in clay is a glass at low temperature, undergoes one or two continuous glass transitions between 150 and 270 K, and behaves as free liquid water above 273 K. The two glass transitions might correspond to two types of water molecules: (i) first adsorbed water molecules, bound to the interlayer cations of the clay mineral; (ii) last adsorbed water molecules, not bound to the interlayer cations. In addition, water vapor adsorption isotherms are obtained from 298 to 378 K (magnetic suspension thermobalance) and well fitted with a BET type model (with three layers of adsorbed water molecules). The Gibbs free energy of the adsorption reaction and the Gibbs free energy of hydration, for any hydration state, can be determined. They are in agreement with the above calorimetric values. Gailhanou H., van Miltenburg J.C., Rogez J., Olives J., Amouric M., Gaucher E.C., Blanc P. (2007).Thermodynamic properties of anhydrous smectite, illite and illite-smectite. (Part 1) Geochim Cosmochim. Acta 71, 5463-5473.

Gailhanou, Helène; Amouric, Marc; Olives, Juan; Rogez, Jacques; van Miltenburg, J. C.; van der Berg, G. J. K.; de Weireld, G.; Gaucher, E.; Blanc, P.

2010-05-01

4

Adhesion force between cyclopentane hydrate and mineral surfaces.  

Science.gov (United States)

Clathrate hydrate adhesion forces play a critical role in describing aggregation and deposition behavior in conventional energy production and transportation. This manuscript uses a unique micromechanical force apparatus to measure the adhesion force between cyclopentane hydrate and heterogeneous quartz and calcite substrates. The latter substrates represent models for coproduced sand and scale often present during conventional energy production and transportation. Micromechanical adhesion force data indicate that clathrate hydrate adhesive forces are 5-10× larger for calcite and quartz minerals than stainless steel. Adhesive forces further increased by 3-15× when increasing surface contact time from 10 to 30 s. In some cases, liquid water from within the hydrate shell contacted the mineral surface and rapidly converted to clathrate hydrate. Further measurements on mineral surfaces with physical control of surface roughness showed a nonlinear dependence of water wetting angle on surface roughness. Existing adhesive force theory correctly predicted the dependence of clathrate hydrate adhesive force on calcite wettability, but did not accurately capture the dependence on quartz wettability. This comparison suggests that the substrate surface may not be inert, and may contribute positively to the strength of the capillary bridge formed between hydrate particles and solid surfaces. PMID:24266729

Aman, Zachary M; Leith, William J; Grasso, Giovanny A; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2013-12-17

5

Chemical characteristics of mineral trioxide aggregate and its hydration reaction.  

Science.gov (United States)

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 hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed. PMID:23429542

Chang, Seok-Woo

2012-11-01

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Chemical characteristics of mineral trioxide aggregate and its hydration reaction  

OpenAIRE

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...

Chang, Seok-woo

2012-01-01

7

Early hydration of portland cement with crystalline mineral additions  

International Nuclear Information System (INIS)

This research presents the effects of finely divided crystalline mineral additions (quartz and limestone), commonly known as filler, on the early hydration of portland cements with very different mineralogical composition. The used techniques to study the early hydration of blended cements were conduction calorimeter, hydraulicity (Fratini's test), non-evaporable water and X-ray diffraction. Results showed that the stimulation and the dilution effects increase when the percentage of crystalline mineral additions used is increased. Depending on the replacement proportion, the mineralogical cement composition and the type of crystalline addition, at 2 days, the prevalence of the dilution effect or the stimulation effect shows that crystalline mineral additions could act as sites of heat dissipation or heat stimulation, respectively

8

Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris  

Science.gov (United States)

New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry.

Roach, Leah H.; Mustard, John F.; Swayze, Gregg; Milliken, Ralph E.; Bishop, Janice L.; Murchie, Scott L.; Lichtenberg, Kim

2010-03-01

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The formation of goethite and hydrated clay minerals on Mars  

Science.gov (United States)

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.

Huguenin, R. L.

1974-01-01

10

Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles  

Directory of Open Access Journals (Sweden)

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.

A. Salam

2007-01-01

11

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

Science.gov (United States)

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

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

2011-01-01

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E-class Asteroids: Troilite, Hydrated Minerals, Both, or Neither?  

Science.gov (United States)

E-class asteroids in the taxonomy of Tholen (1984) have flat spectra through the 0.3--1.0 ? m region, and high albedos (usually above 0.3). they dominate the Hungaria region of the asteroid belt, though a few E asteroids (notably the largest ones, 44 Nysa and 64 Angelina) can be found scattered much further out. These asteroids have been associated with the aubrite (enstatite achondrite) meteorites, which are thought to be of igneous origin (Gaffey et al. 1989, Kelley and Gaffey 1995). Rivkin et al. (1995) found an absorption feature at 3 ? m on 44 Nysa and a possible feature on 64 Angelina. Rivkin (1997) presented observations of 6 E-class asteroids (none of them Hungaria region asteroids), and found the 3-? m absorption feature on 4 of them. Because the 3-? m absorption is diagnostic for water- and/or hydroxyl-bearing minerals, this implies a different history for these E asteroids than what is indicated by the aubrites. Bus (1999) during a spectroscopic study found that some E-class asteroids have an absorption feature near 0.5 ? m. Troilite has been suggested as the agent responsible for this visible feature (Cloutis and Burbine 1999), though some serious objections to troilite remain (Fornasier and Lazzarin 2001). Cloutis and Burbine suggested that troilite rather than hydrated minerals could be responsible for the 3-? m feature as well, based on spectra of iron-bearing zinc sulfides and new troilite spectra they obtained. We consider this hypothesis as well as other alternative interpretations of the 3-? m absorption band, using the set of available laboratory and astronomical data as well as geological arguments and newly-obtained IRTF data. We acknowledge support from the NASA Planetary Astronomy Program. GBA.

Rivkin, A. S.; Howell, E. S.

2001-11-01

13

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...

14

Immunomodulatory effects of mineral fibres in occupationally exposed workers.  

Science.gov (United States)

In the context of a large-scale molecular epidemiology study, the possible immunomodulatory effects of mineral fibres, in workers occupationally exposed to asbestos, rockwool and glass fibres, were examined. In each plant, 61, 98 and 80 exposed workers and 21, 43 or 36 control clerical subjects, respectively, were recruited. In the case of the asbestos-exposed subjects, an additional town-control group of 49 people was included. Evidence of pulmonary fibrosis was found in 42% of the asbestos-exposed workers, while evidence of pleural fibrosis was found in 24%. The asbestos-exposed cohort had significantly decreased forced vital capacity of lungs as well as forced expiratory volume per first second. Our findings indicate that exposure to all three types of fibres examined modulates to different degrees the immune response. Suppression of T-cell immunity and to a lesser extent, B-cell immunity was found in the case of workers from a former asbestos cement plant, while stimulation of T-cell response was observed in rockwool workers, and stimulation of T- and B-cell response was seen in glass fibre workers. Depression of the percentage of lymphocyte subpopulation of CD 16+56 (natural killer cells) in peripheral blood was found in glass fibre workers. Statistical analysis showed increased levels of proinflammatory cytokines (IL-6 asbestos; IL-8 all three fibres), expression of adhesion molecule L-selectin on granulocytes and monocytes (asbestos), levels of soluble adhesion molecules (SAMs) in sera (ICAM-1 all three fibres; E-selectin glass fibres), increased levels of immunoglobulin E (asbestos and rockwool) and elevated expression of activation markers on eosinophils (CD66b asbestos, glass fibres; CD69 asbestos). Significant correlations were observed between lymphocyte proliferation and markers of DNA damage and repair. Increased levels of proinflammatory cytokines, SAMs, immunoglobulin E and elevated expression of activation markers on eosinophils was found in people with symptoms of hypersensitivity and an elevated inflammatory status. PMID:15288538

Tulinska, Jana; Jahnova, Eva; Dusinska, Maria; Kuricova, Miroslava; Liskova, Aurelia; Ilavska, Silvia; Horvathova, Mira; Wsolova, Ladislava; Kyrtopoulos, Soterios A; Collins, Andrew; Harrington, Vikki; Fuortes, Laurence

2004-09-01

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Elastic properties of hydrated minerals : applications to the seismic anisotropy in the subduction zones  

OpenAIRE

The flow of material and the seismic signature of subduction zones are highly dependent on the elastic propertiesof two major types of hydrated minerals: serpentines (antigorite, lizardite and chrysotile) produced by thehydration of mantle minerals and glaucophane, a marker of blueschists and eclogites, which are metamorphicfacies characteristic of subduction zones. Detection of these phases is sometime difficult. It is important to knowtheir elastic properties in order to better understand t...

Bezacier, Lucile

2011-01-01

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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  

International Nuclear Information System (INIS)

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 ?m) scale for determination of H at fraction of atomic percent level. 9 refs., 3 figs

18

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

19

Atomistic simulations of clay minerals subject to variably hydrated supercritical CO2  

Science.gov (United States)

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.

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

2012-12-01

20

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

Science.gov (United States)

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

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

2013-12-01

21

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

Directory of Open Access Journals (Sweden)

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.

Heil Daniel P

2010-09-01

22

Bronchial dysplasia induced by radiation in miners exposed to 222Rn progeny  

International Nuclear Information System (INIS)

The objectives were to investigate whether sputum cytology can be used to monitor epithelial cell changes in groups at high risk of lung cancer from exposure to radiation. Dysplasia of bronchial cells was investigated by means of sputum cytology in a group of 434 underground miners. 100 of them were not exposed, and 334 were exposed to 222Rn progeny at cumulative exposures <450 working level months. The frequency of dysplasia in the exposed group was significantly higher than that in the not exposed group (P <0.0001), and an exposure-response relation was found. This relation was different for smokers and non-smokers. (author)

23

Silica-rich deposits and hydrated minerals at Gusev Crater, Mars: Vis-NIR spectral characterization and regional mapping  

Science.gov (United States)

The Mars Exploration Rover (MER) Spirit has discovered surprisingly high concentrations of amorphous silica in soil and nodular outcrops in the Inner Basin of the Columbia Hills. In Pancam multispectral observations, we find that an absorption feature at the longest Pancam wavelength (1009 nm) appears to be characteristic of these silica-rich materials; however, spectral analyses of amorphous silica suggest that the ˜1009 nm spectral feature is not a direct reflection of their silica-rich nature. Based on comparisons with spectral databases, we hypothesize that the presence of H 2O or OH, either free (as water ice), adsorbed or bound in a mineral structure, is responsible for the spectral feature observed by Pancam. The Gertrude Weise soil, which is nearly pure opaline silica, may have adsorbed water cold-trapped on mineral grains. The origin of the ˜1009 nm Pancam feature observed in the silica-rich nodular outcrops may result from the presence of additional hydrated minerals (specific sulfates, halides, chlorides, sodium silicates, carbonates or borates). Using the ˜1009 nm feature with other spectral parameters as a "hydration signature" we have mapped the occurrence of hydrated materials along the extent of Spirit's traverse across the Columbia Hills from West Spur to Home Plate (sols 155-1696). We have also mapped this hydration signature across large panoramic images to understand the regional distribution of materials that are spectrally similar to the silica-rich soil and nodular outcrops. Our results suggest that hydrated materials are common in the Columbia Hills.

Rice, M. S.; Bell, J. F.; Cloutis, E. A.; Wang, A.; Ruff, S. W.; Craig, M. A.; Bailey, D. T.; Johnson, J. R.; de Souza, P. A.; Farrand, W. H.

2010-02-01

24

Silica-rich deposits and hydrated minerals at Gusev Crater, Mars: Vis-NIR spectral characterization and regional mapping  

Science.gov (United States)

The Mars Exploration Rover (MER) Spirit has discovered surprisingly high concentrations of amorphous silica in soil and nodular outcrops in the Inner Basin of the Columbia Hills. In Pancam multispectral observations, we find that an absorption feature at the longest Pancam wavelength (1009 nm) appears to be characteristic of these silica-rich materials; however, spectral analyses of amorphous silica suggest that the ???1009 nm spectral feature is not a direct reflection of their silica-rich nature. Based on comparisons with spectral databases, we hypothesize that the presence of H2O or OH, either free (as water ice), adsorbed or bound in a mineral structure, is responsible for the spectral feature observed by Pancam. The Gertrude Weise soil, which is nearly pure opaline silica, may have adsorbed water cold-trapped on mineral grains. The origin of the ???1009 nm Pancam feature observed in the silica-rich nodular outcrops may result from the presence of additional hydrated minerals (specific sulfates, halides, chlorides, sodium silicates, carbonates or borates). Using the ???1009 nm feature with other spectral parameters as a "hydration signature" we have mapped the occurrence of hydrated materials along the extent of Spirit's traverse across the Columbia Hills from West Spur to Home Plate (sols 155-1696). We have also mapped this hydration signature across large panoramic images to understand the regional distribution of materials that are spectrally similar to the silica-rich soil and nodular outcrops. Our results suggest that hydrated materials are common in the Columbia Hills. ?? 2009 Elsevier Inc.

Rice, M.S.; Bell, J.F., III; Cloutis, E.A.; Wang, A.; Ruff, S.W.; Craig, M.A.; Bailey, D.T.; Johnson, J.R.; De Souza, P.A., Jr.; Farrand, W.H.

2010-01-01

25

Occurrence and Hydration State of Smectite Minerals in Hole C0009 of the NanTroSEIZE Project (expedition 319)  

Science.gov (United States)

Clays can absorb significant volumes of water, as well as various cations or organic substances onto and/or into their crystal structure, leading to important variations in material behavior. The NanTroSEIZE drilling project offers an outstanding opportunity to study the properties of smectite clay minerals in sediments that are progressively transported by a subduction system into the seismogenic zone. Based on a detailed mineralogical study of mudrock samples from core C0009 drilled during Expedition 319, we present new X-ray diffraction (XRD) and Transmission electron microscopy (TEM) results from depth between 1510 and 1594 mbsf. General mineral identification reveals the occurrence of smectite and illite clay minerals, together with chlorite, quartz, feldspar and calcite. Clay analysis show discrete smectite phases with two to three water layers after ethylene glycolization. In order to investigate and compare the in-situ hydration state of these minerals at different depth, some samples were embedded and polymerized immediately after arriving at the surface during Expedition 319. Preliminary high-resolution TEM analysis of these impregnated rocks show mostly large, detrital particles of about 150 nm thicknesses and a long-range ordering (R > 3). Some smaller grains (~ 50 nm thick) show less ordering and wavier layers, and are probably of authigenic origin. The smectite particles show two water layers on average at all depths. The microstructures and hydration states will be compared with un-impregnated samples from the same depths to investigate the changes in hydration state. We also observed smectitic phases along polished surfaces with occasional slip striations. The striations are interpreted as recent faulting features, analogous to observations elsewhere, and may have developed during forearc development or even beneath the Kumano basin. Of particular interest is the location of the smectite minerals, because they are particularly weak as a result of the easy breakage of H2O-H2O bonds and intracrystalline slip along basal layers. Detailed characterization of the hydration state of swelling clays with depth in their original setting is critical for our understanding of clay-fluid interaction and mechanical properties during crustal displacements and seismotectonics.

Schleicher, A. M.; van der Pluijm, B. A.; Expedition 319 Scientists

2010-12-01

26

Development of a consistent set of standard thermodynamic properties for clay minerals, zeolites and portland cement hydrates  

International Nuclear Information System (INIS)

Document available in extended abstract form only. Cementitious grouts will be used to reduce the ingress of groundwater during the construction of deep geologic repositories for high-level nuclear wastes. Secondary zeolites, clay minerals and Portland cement hydrates could precipitate if cement-derived alkaline leachates react with the host rock. The effects of such reactions on the local geochemical environment should therefore be considered in assessments of the long-term safety of repository designs. In order to support such assessments standard Gibbs free energies and enthalpies of formation (?Gof and ?Hof, respectively), standard entropies (So) and standard isobaric heat capacities (Cop) for selected clay minerals and zeolites were estimated using the polymer model and associated additivity algorithms. Corresponding values for Portland cement hydrates were also re-calculated from literature values. The resultant set of properties are internally consistent insofar as all they are all based on a common set of ?Gof and ?Hof values for model components, and on a common set of reliable thermodynamic data for aqueous species, gases, minerals, and reactions. For zeolites, development of the polymer model entailed the calibration of adjustable model parameters using a linear regression technique constrained by ?Gof and ?Hof and ?Hof values retrieved from calorimetric, solubility and phase-equilibrium experiments, and assessments of model accuracy based on comparisons of predicted values with experimental counterparts not included in the calibration dataset. The ?Gof and ?Hof predictions were found to average within ±0.2% and ±0.3%, respectively, of experimental values at 298.15 K, 1 bar. The latter result is comparable to the good accuracy that has been obtained using a more rigorous electronegativity-based model for ?Hof that accounts explicitly for differences in zeolite structure based on differences in framework density and unit-cell volume. The polymer model was also used to estimate ?Gof for clay minerals, including di-octahedral smectites and illites. Adjustable model parameters were calibrated using experimental constraints on the ion exchange properties of four montmorillonites. Additivity and structural analogue algorithms for 2:1 phyllosilicates were also developed to estimate So and Cop(T) values for 26 smectites. The algorithms were constrained by Cop(T) and So values determined in a recent calorimetric investigation of an anhydrous MX-80 smectite. The estimated So values for each of the 26 smectites were used with the Gibbs-Helmholtz relation and ?Gof to calculate corresponding values of ?Hof at 298.15 K and 1 bar. The model produced ?Gof estimates for smectites that averaged within ±0.24% of their experimental counterparts, all but one of which were retrieved from measured solubilities. The model also produced reasonably accurate estimates of ?Gof for illites based on a limited number of direct comparisons between experimental and estimated values. This good agreement overall is noteworthy given conceptual limitations and experimental difficulties in accurately determining clay mineral solubilities. For Portland cement clinker and hydrate phases, standard thermodynamic properties retrieved from solubility and phase-equilibrium experiments at temperatures up to 373.15 K were re-calculated in order to establish consistency with the standard partial molar properties of aqueous solutes, notably Al3+ and AlO2-, adopted in thermodynamic databases developed by JAEA and others. When used with these databases, the re-calculated values eliminate significant errors in calculated solubility products (Ksp). Such errors can amount, for example, to a difference of 1.4 log units in Ksp for cement hydrates having 2 Al atoms per formula unit. The estimated and re-calculated properties for zeolites, clay minerals, and cement hydrates were used to construct diagrams depicting the stability fields o f these minerals and an aqueous phase in various chemical sub-systems as a function of the activities and activit

27

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

28

Neurophysiological anomalies in brainstem responses of mercury-exposed children of Andean gold miners.  

Science.gov (United States)

The health hazards of occupational exposure to Mercury (Hg) in adult gold miners are well known, but little attention has been given to the effects of Hg exposure in the children of gold miners. Children who assist their parents in gold mining operations or live in mining enclaves may be exposed to elemental Hg vapors or methylmercury-contaminated food, both of which may induce neurodevelopmental disabilities. Brainstem auditory-evoked responses (BAER) were measured as biomarkers of subtle mercury-induced neurological impairment in Andean children of gold miners living in the Ecuadorian gold mining settlement of Nambija, where Hg exposure is prevalent. Thirty-one children (19 boys and 12 girls, aged 4-14 years, mean age: 10 years) in the study group were found to have a mean blood mercury (HgB) level of 23.0 micrograms/L (SD: 19, range: 2.0-89.0 micrograms/L; median: 20 micrograms/L), which was significantly higher than the mean HgB level of a reference group of 21 Ecuadorian children (4.5 micrograms/L, SD: 2.3; t = 4.39, P = 0.0001), and in excess of the health-based biological limits for the U.S. (10 micrograms/L). The BAER measures indicated statistically significant differences in interpeak III-V (P = 0.03) and I-V (P = 0.008) neural conduction times for children with HgB levels above the median. BAERs at the conventional click stimulus rate of 10/second showed statistically significant positive correlations between HgB level and the absolute latency of wave V (P = 0.03), and the neural conduction times of the eighth nerve to midbrain I-V interval (P = 0.02). BAER at 50/second revealed statistically significant relationships between HgB and the latency of wave VI (P = 0.03), and the I-VI interpeak interval (P = 0.02). Brainstem neural conduction times suggested that some of the Hg-intoxicated children in the study group have subtle neurophysiological anomalies that may be more manifest at higher BAER stimulus rates, and that the Hg-exposed children of gold miners are at risk for neurodevelopmental disabilities. PMID:12553183

Counter, S Allen

2003-01-01

29

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

30

A vibrational spectroscopic study of hydrated Fe 3+ hydroxyl-sulfates; polymorphic minerals butlerite and parabutlerite  

Science.gov (United States)

Raman and infrared spectra of two polymorphous minerals with the chemical formula Fe 3+(SO 4)(OH)·2H 2O, monoclinic butlerite and orthorhombic parabutlerite, are studied and the spectra assigned. Observed bands are attributed to the (SO 4) 2- stretching and bending vibrations, hydrogen bonded water molecules, stretching and bending vibrations of hydroxyl ions, water librational modes, Fe-O and Fe-OH stretching vibrations, Fe-OH bending vibrations and lattice vibrations. The O-H⋯O hydrogen bond lengths in the structures of both minerals are calculated from the wavenumbers of the stretching vibrations. One symmetrically distinct (SO 4) 2- unit in the structure of butlerite and two symmetrically distinct (SO 4) 2- units in the structure of parabutlerite are inferred from the Raman and infrared spectra. This conclusion agrees with the published crystal structures of both mineral phases.

?ejka, Ji?í; Sejkora, Ji?í; Plášil, Jakub; Bahfenne, Silmarilly; Palmer, Sara J.; Frost, Ray L.

2011-09-01

31

Thermodynamics of Uranyl Minerals: Enthalpies of Formation of Uranyl Oxide Hydrates  

International Nuclear Information System (INIS)

The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO2)4O(OH)6](H2O)5, metaschoepite; ?-UO2(OH)2; CaUO4; Ca(UO2)6O4(OH)6(H2O)8, becquerelite; Ca(UO2)4O3(OH)4(H2O)2; Na(UO2)O(OH), clarkeite; Na2(UO2)6O4(OH)6(H2O)7, the sodium analogue of compreignacite and Pb3(UO2)8O8(OH)6(H2O)2, curite. The enthalpy of formation from the binary oxides, ?Hf-ox, at 298 K was calculated for each compound from the respective drop solution enthalpy, ?Hds. The standard enthalpies of formation from the elements, ?Hfo, at 298 K are -1791.0 ± 3.2, -1536.2 ± 2.8, -2002.0 ± 3.2, -11389.2 ± 13.5, -6653.1 ± 13.8, -1724.7 ± 5.1, -10936.4 ± 14.5 and -13163.2 ± 34.4 kJ mol-1, respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments

32

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

OpenAIRE

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,...

Baig, Khuram

2009-01-01

33

A discussion on improving hydration activity of steel slag by altering its mineral compositions.  

Science.gov (United States)

This study aims to investigate the ways to improve the cementitious properties of steel slag. The results show that the cementitious phase of steel slag is composed of silicate and aluminate, but the large particles of these phases make a very small contribution to the cementitious properties of steel slag. RO phase (CaO-FeO-MnO-MgO solid solution), Fe(3)O(4), C(2)F and f-CaO make no contribution to the cementitious properties of steel slag. A new kind of steel slag with more cementitious phase and less RO phase can be obtained by removing some large particles. This new steel slag possesses better cementitious properties than the original steel slag. The large particles can be used as fine aggregates for concrete. Adding regulating agent high in CaO and SiO(2) during manufacturing process of steel slag to increase the cementitious phase to inert phase ratio is another way to improve its cementitious properties. The regulating agent should be selected to adapt to the specific steel slag and the alkalinity should be increased as high as possible on the premise that the f-CaO content does not increase. The cooling rate should be enhanced to improve the hydration activity of the cementitious phase at the early ages and the grindability of steel slag. PMID:21168967

Wang, Qiang; Yan, Peiyu; Feng, Jianwen

2011-02-28

34

Stable isotope fractionation factors of water in hydrated saline mineral-brine systems  

Science.gov (United States)

Hydrogen and oxygen isotope fractionation factors of water between water of crystallization of carnallite, bischofite and tachyhydrite and the mother solutions were determined from the isotopic activity ratios of the mother solutions (? a) in the temperature range of 10-40°C. Deuterium is depleted and 18O enriched in the water of crystallization of all these minerals. No clear temperature dependence can be observed. The published fractionation factors in the literature, which were all determined from the isotopic concentration ratios of the mother solutions (? c) were corrected to ? a using the "salt effect" coefficients. It is proposed that only the ? a values can be applied to the natural settings.

Horita, Juske

1989-10-01

35

Mineral replacement reactions in naturally occurring hydrated uranyl phosphates from the Tarabau deposit: Examples in the Cu–Ba uranyl phosphate system  

OpenAIRE

Uranyl phosphates are a mineral group which include a wide range of different species, each containing specific cations within the hydrated interlayer, and often display a geochemical/mineralogical relationship with Fe(III) oxy-hydroxides. The environmental relevance of these U-phases arises from their low solubility at most surface and groundwater conditions, where they can ultimately control aqueous U levels. In the present work, samples of naturally occurring uranyl phosphates ...

Pinto, Andre? Filipe Jorge; Conc?alves, Ma?rio A.; Praceres, Ca?tia; Astilleros Garci?a-monge, Jose? Manuel; Batista, Maria Joao

2012-01-01

36

Effects of hydrated sodium calcium aluminosilicate on fescue toxicosis and mineral absorption.  

Science.gov (United States)

The possibility of supplementing livestock diets with an aluminosilicate to protect them from fescue toxicosis was investigated. An in vitro study showed that hydrated sodium calcium aluminosilicate (HSCAS) removed greater than 90% of the ergotamine from aqueous solutions at pH 7.8 or lower, indicating a high affinity of ergotamine for HSCAS in vitro. Rats fed diets containing tall fescue seed infested (E+) with the endophytic fungus Acremonium coenophialum had lower (P less than .05) feed intakes and weight gains than did rats fed diets containing uninfested (E-) tall fescue seed. When feed intake by rats fed the E- seed diet was limited to that of rats fed the E+ seed diet, weight gains did not differ, but testes weights and serum prolactin (PRL) concentrations were lower (P less than .05 and .10, respectively) in rats receiving E+ seed. Supplementing E+ seed diets with HSCAS did not eliminate effects of E+ seed on intake, PRL, or testes weights. Sheep fed E+ tall fescue hay had higher (P less than .05) rectal temperatures than did sheep fed an equal amount of E- tall fescue hay, but OM and N digestion coefficients did not differ between the two hays. Supplementing E+ hay diets with HSCAS did not eliminate the effect of E+ hay on rectal temperatures. Addition of 2% HSCAS to tall fescue hay diets did not affect apparent absorption by sheep of OM, N, Ca, P, Na, K, or Cu, but it reduced (P less than .05) the apparent absorption of Mg, Mn, and Zn.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1328128

Chestnut, A B; Anderson, P D; Cochran, M A; Fribourg, H A; Gwinn, K D

1992-09-01

37

Microstructures and Chemistry of Serpentine Minerals in Veins: Constraints on the Hydration Processes of Oceanic Peridotites  

Science.gov (United States)

Serpentine minerals are hydrous sheet silicates forming in various geological settings (oceanic extension, subduction, transform faulting) by hydrothermal alteration of magnesian silicates, major components of mantle rocks. They are known to display a large variety of structural types (chrysotile, polygonal serpentine, lizardite, antigorite) whose relative stabilities are poorly constrained by P, T and chemistry. Recent experimental studies suggest that other parameters such as the water-rock ratio, crystallization kinetics, and deformation may affect formation of serpentine types. This study investigates the role of these parameters in natural settings to test if the wide range of serpentine microstructures can record environmental conditions of crystallization. Oceanic serpentinization is accompanied by abundant veining showing different generations of veins with various morphologies and internal textures corresponding to different opening and crystallization conditions. We have selected a representative and extensive set of veins from oceanic serpentinites. We present a detailed chemical, micro- and nano-structural study of the vein-filling serpentine minerals. Vein formation mechanisms are deduced from morphology and texture which then provide constraints on serpentine crystallization conditions. In addition to petrological observations, genetic relationships among the different serpentine types in veins have been identified at different scales using a wide variety of techniques (RAMAN spectroscopy, SEM, TEM, and chemical analyses). The relative importance of parameters that control microstructure stability of serpentines is compared with those obtained from laboratory experiments. These results show how the suite of serpentine microstructures observed in veins is linked to the evolution of environmental conditions (T, chemistry, W/R, mass transfer process-deformation, kinetic) during serpentinization.

Andreani, M.; Mevel, C.; Boullier, A.; Baronnet, A.

2005-12-01

38

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)

39

Radiographic Emphysema Predicts Low Bone Mineral Density in a Tobacco-exposed Cohort  

OpenAIRE

Rationale: Studies demonstrating an association between chronic obstructive pulmonary disease and low bone mineral density (BMD) implicate factors distinct from treatments and severity of lung disease in the pathogenesis of osteoporosis. Whereas emphysema has been independently associated with vascular disease and other comorbidities, its association with BMD has not been well studied.

Bon, Jessica; Fuhrman, Carl R.; Weissfeld, Joel L.; Duncan, Steven R.; Branch, Robert A.; Chang, Chung-chou H.; Zhang, Yingze; Leader, Joseph K.; Gur, David; Greenspan, Susan L.; Sciurba, Frank C.

2011-01-01

40

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

41

Evaluation of materials exposed to high-velocity, high-salinity, highly mineralized geothermal brine  

Energy Technology Data Exchange (ETDEWEB)

Using surface traces, scanning electron microscopy, and light microscopy, Ti-, Co-, Ni-, and Fe-base alloys were evaluated for erosion and stress corrosion cracking (SCC) after exposure at about 104{sup 0}C to the nozzle exhaust from acidified geothermal brine. Examples of erosion, SCC, and corrosion are shown. Results are evaluated in terms of synergism between erosion, corrosion, and stress. Repassivation kinetics might play a key role in the formation and growth of erosion cavities. Of the materials tested, the Ti-base alloys appear to have the best combination of resistance to SCC and erosion/corrosion in high-salinity, highly mineralized, acidified, two-phase nozzle exhaust.

Goldberg, A.; Kershaw, R.P.

1978-08-20

42

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

43

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-11-01

44

Chromosomal aberrations in lymphocytes of employees in transformer and generator production exposed to electromagnetic fields and mineral oil.  

Science.gov (United States)

The objective was to study the risk of cytogenetic damage among high voltage laboratory workers exposed to electromagnetic fields and mineral oil. This is a cross sectional study of 24 exposed and 24 matched controls in a Norwegian transformer factory. The exposure group included employees in the high voltage laboratory and in the generator soldering department. Electric and magnetic fields and oil mist and vapor were measured. Blood samples were analyzed for chromosomal aberrations in cultured lymphocytes. In addition to conventional cultures, the lymphocytes were also treated with hydroxyurea and caffeine. This procedure inhibits DNA synthesis and repair in vitro, revealing in vivo genotoxic lesions that are repaired during conventional culturing. In conventional cultures, the exposure group and the controls showed similar values for all cytogenetic parameters. In the DNA synthesis- and repair-inhibited cultures, generator welders showed no differences compared to controls. Among high voltage laboratory testers, compared to the controls, the median number of chromatid breaks was doubled (5 vs. 2.5 per 50 cells; P0.05) and the median number of aberrant cells was 5 vs. 3.5 (Poil exposure may produce chromosomal aberrations. PMID:11255210

Skyberg, K; Hansteen, I L; Vistnes, A I

2001-04-01

45

Elastic anisotropy of uniaxial mineralized collagen fibers measured using two-directional indentation. Effects of hydration state and indentation depth  

OpenAIRE

Mineralized turkey leg tendon (MTLT) is an attractive model of mineralized collagen fibers, which are also present in bone. Its longitudinal structure is advantageous for the relative simplicity in modeling, yet its anisotropic elastic properties remain unknown. The aim of this study was to quantify the extent of elastic anisotropy of mineralized collagen fibers by using nano- and microindentation to probe a number on MTLT samples in two orthogonal directions. The large dataset allowed the qu...

Spiesz, Em; Roschger, P.; Zysset, Phk

2012-01-01

46

Mineral status and mechanical properties of lumbar spine of female rats chronically exposed to various levels of cadmium.  

Science.gov (United States)

The effects of chronic exposure to cadmium (Cd) on the mineral status, mechanical properties and incidence of deformities and fractures of the lumbar spine (L1-L5) were studied in a rat model of human exposure. Young female Wistar rats were exposed to 1, 5, 50 or 100 mg Cd/l for 12 months. Cd, dose and time dependently, disturbed the mineral status of the lumbar vertebrae as reflected in decreased bone mineral content (BMC) and density (BMD) at the L1-L5 (DEXA technique) and ash weight (AW) of the fourth lumbar vertebral body (L4). However, the changes were too small to be evident radiographically. Cd had no effect on the ratio of nonorganic to organic component content, except for its decrease at the 100 mg Cd/l. Weakness in the mechanical properties (compression test; Instron machine) of the L4 was noted. At the 1 mg Cd/l, a decrease was observed in the deformation at the yield point, with a simultaneous increase in the L4 stiffness, but not in strength (defined by load at yield or ultimate load). In the 5 mg Cd/l group, similar changes took place and a decrease in the ultimate load was evident as well. At the 50 and 100 mg Cd/l, Cd more seriously affected the L4 mechanical properties. At all levels of Cd exposure, the L4 deformities and/or fractures took place. Intact L4 was noted only in the 1 and 5 mg Cd/l groups. The study clearly revealed that chronic exposure to Cd disturbs the L1-L5 mineral status resulting in weakness in its mechanical properties and in turn in vertebral body (cancellous bone) deformities and fractures. The results allow us to conclude that the critical Cd concentration for these effects is very low [about 0.06-0.09 microg/g dry defatted weight (DW)] and seem to indicate an osteoporotic character of changes. A very important finding of the study is that Cd affects cancellous bone even at low-level intoxication corresponding to the general population exposure. Thus, we hypothesize that environmental exposure to Cd may be a risk factor for the lumbar spine demineralization and increased incidence of vertebral deformities and fractures. PMID:15003799

Brzóska, M M; Majewska, K; Moniuszko-Jakoniuk, J

2004-03-01

47

Mars residual north polar cap - Earth-based spectroscopic confirmation of water ice as a major constituent and evidence for hydrated minerals  

Science.gov (United States)

A description is presented of new earth-based reflectance spectra of the Martian north residual polar cap. The spectra indicate that the composition is at least mostly water ice plus another component with a 'gray' reflectance. The other minerals in the ice cap appear to be hydrated. The data were obtained with a cooled circular variable filter spectrometer on February 20, 1978, using the 2.2-m telescope on Mauna Kea, Hawaii. It is pointed out that the identification of water ice in the north polar cap alone does not indicate that water makes up all or even most of the bulk of the cap. Kieffer (1970) has shown that a small amount of water will mask the spectral features of CO2.

Clark, R. N.; Mccord, T. B.

1982-01-01

48

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)

49

Long-term mineral stability of bentonites exposed to elevated temperature in neutral, alkaline and salty environments of natural analogues  

International Nuclear Information System (INIS)

Many experiments were performed to predict the long-term behavior of clay barriers at higher temperatures, different pH conditions, and salt concentrations. Nevertheless, the level of knowledge is far from the point where we are able to give a clear picture of the bentonite clay evolution in the long-term perspective. The only way how to tackle the problem of the time frame for the stability of bentonites is to find and study natural analogues which were exposed to the factors of different geochemical environments for a real time. We bring the results of natural analogues for long-term exposure of buried bentonite beds to the temperature between 20 and 300 C in neutral, alkaline and salty environments. All studied cases come from the East Slovak Basin Neogene basin with high recent thermal gradient and variable geological and geochemical environments during deposition of sediments and volcano-clastics. Buried bentonite beds are of volcanic origin (rhyolitic to andesitic volcanites) which creates ideal geological analogue to most of the bentonites tested as the potential barrier for the radioactive disposals. Our results are based on the detail study of mineral composition, mechanism of alteration, K-Ar dating, temperature exposure modeling and laboratory testing. They show that smectite as the main component of the bentonites is stable in neutral environment in large temperature interval for millions of years. Temperature up to 100 C is able to deteriorate only 10% ofo 100 C is able to deteriorate only 10% of original bentonite composition. Higher temperatures up to 150 C still preserve 50% of bentonite composition for more than period necessary for radioactive waste disposals live-time. Clearly, smectites in bentonites of volcanic origin are much more temperature resistant than smectites in clay-stones of sedimentary origin. Mechanism of the alteration is continual and controlled by the temperature so it is possible to predict the process. Salty and alkaline environments (documented by the presence of halite and zeolites) along with an elevated temperature enhance the process of smectite alteration. Up to 80% of original smectite mineral in bentonites can be deteriorated at elevated temperature. The time frame and mechanism of smectite alteration is very complex and hardly predictable. It depends very much on the local geochemical conditions. In an extreme case, complete alteration of smectite was observed in geologically short period up to thousands of years at high temperature about 300 C. Results indicate the large risk of bentonite stability in a presence of salts and alkaline environment, however if bentonite is preserved from the influence of these factors it can ensure long time stability even at elevated temperature. (authors)

50

Spectral reflectance properties (0.4-2.5 um) of secondary Fe-oxide, Fe-hydroxide, and Fe-sulfate-hydrate minerals associated with sulfide-bearing mine waste  

Science.gov (United States)

Fifteen Fe-oxide, Fe-hydroxide, and Fe-sulphate-hydrate mineral species commonly associated with sulphide bearing mine wastes were characterized by using X-ray powder diffraction and scanning electron microscope methods. Diffuse reflectance spectra of the samples show diagnostic absorption features related to electronic processes involving ferric and/or ferrous iron, and to vibrational processes involving water and hydroxyl ions. Such spectral features enable field and remote sensing based studies of the mineral distributions. Because secondary minerals are sensitive indicators of pH, Eh, relative humidity, and other environmental conditions, spectral mapping of these minerals promises to have important applications to mine waste remediation studies. This report releases digital (ascii) spectra (spectral_data_files.zip) of the fifteen mineral samples to facilitate usage of the data with spectral libraries and spectral analysis software. The spectral data are provided in a two-column format listing wavelength (in micrometers) and reflectance, respectively.

Crowley, J.K.; Williams, D.E.; Hammarstrom1, J.M.; Piatak, N.; Mars, J.C.; Chou, I-Ming

2006-01-01

51

minerals  

Science.gov (United States)

Polarized electronic absorption spectra of colourless chalcocyanite, CuSO4, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm-1, which have been assigned to crystal field d- d transitions of Cu2+ cations in pseudo-tetragonally elongated CuO6 polyhedra with point symmetry C i (). The polarization behaviour is interpreted based on a D 2( C 2?) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a `classic' pseudo-tetragonal crystal field approach yielding the parameters Dq (eq) = 910, Dt = 395, and Ds = 1,336 cm-1, corresponding to a cubically averaged Dq cub = 679 cm-1. A comparative survey on crystal fields in Cu2+ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu2+ minerals. The weak crystal field in CuSO4 can be related to the lower position of the SO4 2- anion compared to, e.g. the H2O molecule in the spectrochemical series of ligands.

Wildner, Manfred; Giester, Gerald; Kersten, Monika; Langer, Klaus

2014-10-01

52

The French cohort of uranium miners: Analysis of lung cancer risk linked to radon exposure in a population exposed to relatively low concentration over a long duration  

International Nuclear Information System (INIS)

In France, about 5,000 miners have been employed in uranium mining industry since 1946. Most of these miners have experienced relatively low annual exposures in comparison to other cohorts of miners. Consequently, the hypothesis to be tested in our study was the potential risk of cancer in a relatively low exposed population, characterised by a long period of underground work. A first analysis of the ''oldest'' cohort (1,785 miners having worked underground before 1972) has been published in 1993, based on a follow-up to December 1985. Recently, this follow-up has been extended up to 1994. Compared to the first analysis, the size of the cohort has increased by 24 %, and the number of lung cancer deaths has increased by about 90 % (from 45 to 85 deaths). Mean cumulated exposure to radon is of 71.5 WML, protracted over more than 15 years. After 1956, radon exposure is lower than 2 WLM/year for 50 % of the miners. The Standardised Mortality Ratio for lung cancer is 1.65, with confidence interval CI95% = [1.3-2.0]. The Excess Relative Risk coefficient for lung cancer with cumulated exposure to radon is ERR/WLM 0.40 % (p = 0.05). This estimate is very similar to the one obtained in the first analysis. The contribution of this population to the estimation of the risk coefficient of lung cancer, in relation to low dose-rates and low cumulative exposure is far from negligible. Enlargement of the French cohort exposed after 1956 is ongoing. Moreover a European joint analysis of cohorts with low levels of exposure rates (French, Czech and German cohorts) will be performed in a near future. (author)

53

Proliferation and mRNA expression of absorptive villous cell markers and mineral transporters in prolactin-exposed IEC-6 intestinal crypt cells.  

Science.gov (United States)

During pregnancy and lactation, prolactin (PRL) enhances intestinal absorption of calcium and other minerals for fetal development and milk production. Although an enhanced absorptive efficiency is believed to mainly result from the upregulation of mineral transporters in the absorptive villous cells, some other possibilities, such as PRL-enhanced crypt cell proliferation and differentiation to increase the absorptive area, have never been ruled out. Here, we investigated cell proliferation and mRNA expression of mineral absorption-related genes in the PRL-exposed IEC-6 crypt cells. As expected, the cell proliferation was not altered by PRL. Inasmuch as the mRNA expressions of villous cell markers, including dipeptidylpeptidase-4, lactase and glucose transporter-5, were not increased, PRL was not likely to enhance crypt cell differentiation into the absorptive villous cells. In contrast to the previous findings in villous cells, PRL was found to downregulate the expression of calbindin-D(9k), claudin-3 and occludin in IEC-6 crypt cells, while having no effect on transient receptor potential vanilloid family channels-5/6, plasma membrane Ca(2+)-ATPase (PMCA)-1b and Na(+)/Ca(2+) exchanger-1 expression. In conclusion, IEC-6 crypt cells did not respond to PRL by increasing proliferation or differentiation into villous cells. The present results thus supported the previous hypothesis that PRL enhanced mineral absorption predominantly by increasing transporter expression and activity in the absorptive villous cells. PMID:22281785

Teerapornpuntakit, Jarinthorn; Wongdee, Kannikar; Thongbunchoo, Jirawan; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

2012-06-01

54

Evolved gas analysis of hydrated phases in Murchison and Orgueil  

OpenAIRE

To better characterise the hydrated minerals in chondrites Evolved Gas Analysis of Murchison, Orgueil and selected minerals has been carried out. Meteorite water release profiles show significant differences to expected reference minerals.

Morris, A. A.; Baker, L.; Franchi, I. A.; Wright, I. P.

2005-01-01

55

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

OpenAIRE

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...

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

2011-01-01

56

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.

57

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

58

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

Science.gov (United States)

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

Loladze, Irakli

2014-01-01

59

Mineral nutrient imbalance, total antioxidants level and DNA damage in common bean (Phaseolus vulgaris L.) exposed to heavy metals  

OpenAIRE

The present study aimed to analyze the biological effects induced by bioaccumulation of metals in common bean (Phaseolus vulgaris L.). Effects of mineral nutrient imbalance, total antioxidants level and DNA damage induced by accumulation of heavy metals, were investigated in bean seedlings treated with two selected metal concentrations for 7 days. Metal content is analyzed by inductively coupled plasma – atomic emission spectrometer (ICP-AES), for total antioxidants level assessment the Fe...

Gjorgieva, Darinka; Kadifkova Panovska, Tatjana; Ruskovska, Tatjana; Bac?eva, Katerina; Stafilov, Trajc?e

2013-01-01

60

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

OpenAIRE

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 vit...

Adeniyi Francis A. A.; Anetor John I.; Iyanda Ayobola A

2011-01-01

61

Mortality and cancer incidence in a small cohort of miners exposed to low levels of alpha radiation  

International Nuclear Information System (INIS)

Due to the continuing controversy over the effects on humans of low-level ionizing radiation, overall mortality and cancer incidence among miners from a magnetite mine was investigated. The study comprises 332 underground miners. The average concentration of Rn progeny is presently 0.10-0.15 working levels (WL). Included in the study were those employed for more than 36 months in the period 1940-1960, who were still alive in 1953. The follow-up period covers 1953-1980. Mortality was equal to estimated values based on age-specific national figures. The observed/expected ratio for lung cancer incidence was 1.1. Comparison was also made to 190 miners from a mine with negligible radiation (less than 0.02 WL). The same mortality was observed, but this mine showed a ratio for lung cancer incidence of 2.2. The study population is too small to repudiate the hypothesis of increased health risk after exposure to low levels of alpha radiation

62

Theoretical studies of Methane Hydrate Dissociation in porous media using RetrasoCodeBright simulator  

OpenAIRE

Methane hydrates in reservoir are generally not in chemical equilibrium, there may be several competing hydrate phase transitions like for instance hydrate dissociation due to pressure or temperature changes, hydrate reformation, hydrate dissociation due to contact with under saturated fluids and mineral surfaces. The limited numbers of reservoir simulators, which have incorporated hydrate, are normally simplified by considering only pressure and temperature as criteria for hydrate stabil...

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

2012-01-01

63

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.)

64

Mineral nutrient imbalance, total antioxidants level and DNA damage in common bean (Phaseolus vulgaris L.) exposed to heavy metals.  

Science.gov (United States)

The present study aimed to analyze the biological effects induced by bioaccumulation of metals in common bean (Phaseolus vulgaris L.). Effects of mineral nutrient imbalance, total antioxidants level and DNA damage induced by accumulation of heavy metals, were investigated in bean seedlings treated with two selected metal concentrations for 7 days. Metal content is analyzed by inductively coupled plasma - atomic emission spectrometer (ICP-AES), for total antioxidants level assessment the Ferric-Reducing Antioxidant Power (FRAP) assay is used and Random Amplified Polymorphic DNA (RAPD) method was applied for investigation of DNA damages. The increasing metal concentration in the treatment medium changed synchronously metal content in samples, and decreased total antioxidant activity in all samples with exception only for samples treated with Ni and Cd. The obtained "DNA fingerprints" demonstrated that the increasing metal concentrations induced changes in RAPD profiles (disappearance and/or appearance of bands in comparison with untreated control samples). The highest number of missing bands was observed in samples treated with zinc (total 4 bands) and nickel (total 4 bands) at both concentrations. These results suggested that mineral nutrient imbalance is involved in changes of antioxidant levels and DNA damages of the seedlings, which may help to understand the mechanism of metal toxicity in plants. PMID:24431518

Gjorgieva, Darinka; Kadifkova Panovska, Tatjana; Ruskovska, Tatjana; Ba?eva, Katerina; Stafilov, Traj?e

2013-10-01

65

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

Directory of Open Access Journals (Sweden)

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.

Adeniyi Francis A. A.

2011-05-01

66

Integrating dosemeters for the determination of the radiation exposure of miners exposed to short-lived radon daughter products  

International Nuclear Information System (INIS)

For the determination of the radiation exposure by short-lived radon daughters integrating measuring instruments are especially suited, because variations of activity concentrations can cause essential errors using short-term dosemeters. At present a measuring instrument based on thermluminescence detectors is used by the SAAS as a stationary area monitor. An electronic personal dosemeter with a semiconductor detector exists as a prototype. Structure and mechanism of both the measuring instruments are described and the feasibility of application in workplaces exposed to radon daughter products are discussed. Proceeding from experience gained in development and application of these instruments an outlook is given for the possibility to develop an applicable universal component system used for standardization of Ra and Ra daughter dosemeters within the CMEA

67

CO2 Injection in Hydrate Bearing Sandstone with Excess Water  

OpenAIRE

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...

Ha?genvik, Christian

2013-01-01

68

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)

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

Dabidi Roshan Valiollah

2011-07-01

69

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

70

Mineral density and biomechanical properties of bone tissue from male Arctic foxes (Vulpes lagopus) exposed to organochlorine contaminants and emaciation  

DEFF Research Database (Denmark)

We investigated the impact from dietary OC (organochlorine) exposure and restricted feeding (emaciation) on bone mineral density (BMD; g hydroxy-apatite cm(-2)) in femoral, vertebrate, skull and baculum osteoid tissue from farmed Arctic blue foxes (Vulpes lagopus). For femur, also biomechanical properties during bending (displacement [mm], load [N], energy absorption [J] and stiffness [N/mm]) were measured. Sixteen foxes (EXP) were fed a wet food containing 7.7% OC-polluted minke whale (Balaenoptera acutorostrata) blubber in two periods of body fat deposition (Aug-Dec) and two periods of body fat mobilisation (Jan-July) in which the food contained less energy and only 2% blubber. SigmaOC food concentration in the food containing 7.7% whale blubber was 309 ng/g wet mass. This corresponded to a SigmaOC exposure of ca. 17 microg/kg body mass/d and a responding SigmaOC residue in subcutaneous adipose tissue of ca. 1700 ng/g live mass in the 8 EXP fat foxes euthanized after 16 months. A control group (CON) composed of 15 foxes were fed equal daily caloric amounts of clean pork (Sus scrofa) fat. After 16 months, 8 EXP and 7 CON foxes were euthanized (mean body mass=9.25 kg) while the remaining 8 EXP and 8 CON foxes were given restricted food rations for 6 months resulting in a body weight reduction (mean body mass=5.46 kg). The results showed that only BMD(skull) vs. BMD(vertebrae) were significantly correlated (R=0.68; p=0.03; n=10) probably due to a similar composition of trabecular and cortical osteoid tissue. No difference in any of the BMD measurements or femoral biomechanical properties was found between EXP and CON foxes although BMD baculum was 1.6-folds lower in the EXP group. However, lean summer foxes had significantly lower femoral biomechanical properties measured as displacement (mm), energy absorption (J) and time (s) biomechanical properties than fat winter foxes (all p<0.004). This indicates lower stiffness and softer bones from fasting which is in agreement with previous studies. Further, it should be kept in mind when studying bone tissues in Arctic mammals also in order to avoid confounding effects from body condition.

Sonne, Christian; Wolkers, Hans

2008-01-01

71

Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments  

Science.gov (United States)

The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth behavior of gas hydrates in natural sediments. Hydrate of tetrahydrofuran (THF) has long been used for laboratory studies of gas hydrate-bearing sediments to provide close control on hydrate concentrations and to overcome the long formation history of methane hydrate from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule) compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of hydrate-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF hydrate is similar to that between water and methane hydrate. The processes that researchers choose for forming hydrate in sediments in laboratory settings (e.g., from gas, liquid, or ice) and the pore-scale distribution of the hydrate that is produced by each of these processes likely have a more pronounced effect on the measured macroscale properties of hydrate-bearing sediments than do differences between THF and methane hydrates themselves.

Lee, J.Y.; Yun, T.S.; Santamarina, J.C.; Ruppel, C.

2007-01-01

72

The Microstructure of Nankai Trough Methane hydrate sediments by Scanning Electron Microscope  

Science.gov (United States)

The microstructure of Nankai Trough Methane hydrate sediments was observed by Field Emission Scanning Electron Microscope (FE-SEM; JEOL JSM7000F) with an energy dispersive X-ray detector (EDX-detector; JEOL JED2300F). The samples were obtained using Pressure-Temperature Core Sampler (PTCS) that can prevent hydrate dissociation during coring by keeping pressure insitu conditions. Sample that was taken by conventional tools for coring was kept shape by self-prevention nature itself, nevertheless many excellent observations had been reported. Therefore, it was expected that the PTCS core sample was suitable for observing microstructure of methane hydrate occupied in sediments, even though samples were exposed to atmosphere very short time on vessel before storage in liquid nitrogen. In addition, a low-vacuum system and a cryostat sample stage was installed in FE-SEM for observing methane hydrate bearing sediments. The former can make observation until sample chamber pressure is less than 30Pa, and the latter can control temperature from room temperature to 80K. Each sample was trimmed using cryo- system (Gatan Alto2500) at liquid nitrogen temperature and was settled on cryostat sample stage for observation. To compare with images before and after methane hydrate dissociation at the same region, we had made the freezed-dried sample within chamber of FE-SEM under controlling temperature of cryostat sample stage. Sample had been kept observing during drying by a low-vacuum system's work so as to confirm no breakage had been occur. Result of observation, the following were described as microstructural feature of Nankai Trough Methane hydrate bearing sediments, which had been freezed and dried, (1) There are a number of pyrite crystals existing among sand grains, which crystal size are less than 1 micron. (2) Framboidal pyrite can be seen among sand grains. (3) many vacant space can be seen among sand grains ; there are no pyrite and no clay minerals. (4)Pyrite and clay minerals make thin membrane structure around the vacant space. The space occupied by methane hydrate must be blank when hydrate dissociation occur without disturbing microstructure of sediments. This estimation is supported by EDX analysis that carbon detected regions would become vacant spaces by drying. Thus, we concluded that the methane hydrate exists in the vacant space of pore space and is covered with pyrite and clay minerals. These results will become help to understand methane hydrate formation processes in sediments.

Suzuki, K.; Nishimura, O.; Narita, H.

2007-12-01

73

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

74

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

75

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)

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, ? < ?. Aqualite is weakly fluorescent with a dull yellow color under ultraviolet light. The mineral is stable in 50% HCl and HNO3 at room temperature. Weight loss after ignition at 500°C is 9.8%. Aqualite is monoclinic, and the space group is R3. The unit-cell dimensions are a = 14.078(3) Å, c = 31.24(1) Å, V = 5362 Å3, and Z = 3. The strongest reflections in the 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.

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

2007-12-01

76

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

OpenAIRE

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...

Hossainpour, Reza

2013-01-01

77

Hydration of fly ash cement  

Energy Technology Data Exchange (ETDEWEB)

It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO{sub 2} generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.

Etsuo Sakai; Shigeyoshi Miyahara; Shigenari Ohsawa; Seung-Heun Lee; Masaki Daimon [Tokyo Institute of Technology, Tokyo (Japan). Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering

2005-06-01

78

Investigations into surfactant/gas hydrate relationship  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-03-15

79

Experimental Evaluation of Secondary Hydrate Formation during Methane Production in a Reactor Containing Hydrate-Bearing Porous Media  

Science.gov (United States)

Numerical simulations on methane hydrate dissociation have shown that during methane production from hydrate reservoirs and laboratory-scale reactors, secondary hydrate formation developed around the production port and partially blocked gas flow coming from dissociating hydrate. It is desirable to validate the hydrate decomposition in a viable scale at conditions promoting secondary hydrate formation in an attempt to understand its potential impact on natural gas production at a reservoir scale. A series of laboratory experiments has been performed to observe the occurrence of secondary hydrate formation in a laboratory- scale, cylindrical pressure vessel. Methane hydrate formed in a reactor filled with wetted sand was exposed to a pressure drop and thermal stimulation to induce hydrate decomposition. An X-ray CT scanner was used to observe changes in density occurring inside a hydrate core during hydrate formation and dissociation. The results will be discussed in regards to the impact of various hydrological properties of hydrate-bearing porous medium including initial hydrate saturation and distribution.

Seol, Y.; Myshakin, E. M.; Zhang, W.; Warzinski, R. P.

2008-12-01

80

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)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish 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.

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

2013-12-01

81

Gas hydrate contribution to Late Permian global warming  

Science.gov (United States)

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

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

2014-05-01

82

Evidence for cooperative mineralization of diuron by Arthrobacter sp. BS2 and Achromobacter sp. SP1 isolated from a mixed culture enriched from diuron exposed environments.  

Science.gov (United States)

Diuron was found to be mineralized in buffer strip soil (BS) and in the sediments (SED) of the Morcille river in the Beaujolais vineyard repeatedly treated with this herbicide. Enrichment cultures from BS and SED samples led to the isolation of three bacterial strains transforming diuron to 3,4-dichloroaniline (3,4-DCA) its aniline derivative. 16S rRNA sequencing revealed that they belonged to the genus Arthrobacter (99% of similarity to Arthrobacter globiformis strain K01-01) and were designated as Arthrobacter sp. BS1, BS2 and SED1. Diuron-degrading potential characterized by sequencing of the puhA gene, characterizing the diuron-degradaing potential, revealed 99% similarity to A. globiformis strain D47 puhA gene isolated a decade ago in the UK. These isolates were also able to use chlorotoluron for their growth. Although able to degrade linuron and monolinuron to related aniline derivatives they were not growing on them. Enrichment cultures led to the isolation of a strain from the sediments entirely degrading 3,4-DCA. 16S rRNA sequence analysis showed that it was affiliated to the genus Achromobacter (99% of similarity to Achromobacter sp. CH1) and was designated as Achromobacter sp. SP1. The dcaQ gene encoding enzyme responsible for the transformation of 3,4-DCA to chlorocatechol was found in SP1 with 99% similarity to that of Comamonas testosteroni WDL7. This isolate also used for its growth a range of anilines (3-chloro-4-methyl-aniline, 4-isopropylaniline, 4-chloroaniline, 3-chloroaniline, 4-bromoaniline). The mixed culture composed of BS2 and SP1 strains entirely mineralizes (14)C-diuron to (14)CO2. Diuron-mineralization observed in the enrichment culture could result from the metabolic cooperation between these two populations. PMID:25061887

Devers-Lamrani, Marion; Pesce, Stéphane; Rouard, Nadine; Martin-Laurent, Fabrice

2014-12-01

83

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

84

Magnetic Diagenesis in the Gas Hydrate System  

Science.gov (United States)

Natural gas hydrate is a methane-bearing form of ice which occurs in permafrost and continental slope settings. Geochemical processes associated with gas hydrate formation lead to the growth of iron sulphides which have a geophysically measurable magnetic signature. Detailed magnetic investigation and complementary petrological observations were undertaken on unconsolidated sediments from three gas hydrate (GH) settings: permafrost in fluvial-deltaic silts and sands in the Western Canadian Arctic (Japex et al. Mallik 5L-38 in 2002); diamictons and hemipelagics in the Cascadia accretionary wedge west of Vancouver Island (IODP Exp.311 in 2006); and marine sands and hemipelagics from the Bay of Bengal (NGHP Exp.01 in 2007). These magnetic measurements provide stratigraphic profiles which reveal fine scale variations in lithology, magnetic grain size, and paleo-pore fluid geochemistry. The highest magnetic susceptibility values are observed in strata which preserve high initial concentrations of detrital magnetite, such as glacial deposits. The lowest values of magnetic susceptibility are observed where iron has been reduced to paramagnetic pyrite, formed in settings with high methane and sulphate flux such as at methane vents. Enhanced values of magnetic susceptibility characterize the introduction of the ferrimagnetic iron sulphide minerals greigite and smythite. These magnetic minerals are mostly found immediately adjacent to the sedimentary horizons which host the gas hydrate and their textures and compositions indicate rapid disequilibrium crystallization. The observed diagenesis result from the unique physical and geochemical properties of the environment where gas hydrates form: methane is available to fuel microbiological activity and the freezing which accompanied GH crystallization quickly removed pure water, froze the sediments into an impermeable solid and expelled more concentrated brines into the adjacent less permeable strata to the point of inducing fracture formation. Magnetic surveying techniques can help delineate anomalies related to gas hydrate deposits, and magnetic logging of wells and core samples provide information on the original lithology and diagenesis caused by gas hydrate formation.

Enkin, R. J.; Hamilton, T. S.; Esteban, L.

2009-05-01

85

Magnetic Resonance Microscopy of Collagen Mineralization  

OpenAIRE

A model mineralizing system was subjected to magnetic resonance microscopy to investigate how water proton transverse (T2) relaxation times and magnetization transfer ratios can be applied to monitor collagen mineralization. In our model system, a collagen sponge was mineralized with polymer-stabilized amorphous calcium carbonate. The lower hydration and water proton T2 values of collagen sponges during the initial mineralization phase were attributed to the replacement of the water within th...

Chesnick, Ingrid E.; Mason, Jeffrey T.; Giuseppetti, Anthony A.; Eidelman, Naomi; Potter, Kimberlee

2008-01-01

86

The process of hydrate formation in clastic sediments and its impact on their physical properties  

Energy Technology Data Exchange (ETDEWEB)

Studies have indicated that hydrates can be effectively modelled as a kind of non-cementing pore fill. This paper presented the results of experiments conducted to measure the sonic velocities and electrical resistivities of sediment samples as a function of hydrate content. Hydrates were then grown in the presence of sediment grains from dissolved and free gas phases. The influence of mineral surfaces on hydrate crystallization was also investigated. The aim of the study was to understand the inter-relationship between the measurable physical properties of hydrate-bearing sediments and their microstructure. Dependencies of sonic wave velocity and electrical resistivity were analyzed in order to demonstrate their agreement with numerical models for non-cementing hydrate formation. Experiments were then conducted in an optical cell. Data obtained from the experiments showed that no hydrate growth was observed at the surfaces of the sand grains. Electrical resistivity measurements demonstrated that the hydrate formation rate influenced the microscopic hydrate structure. Results showed that the presence of mineral surfaces reduced the amount of supercooling required to initiate hydrate formation. It was concluded that further research is needed to understand the influence of the ratio of the mineral water interface to the water volume, as well as the impact of mineral types and surface charge density. 20 refs., 7 figs.

Spangenberg, E.; Beeskow-Strauch, B.; Luzi, M.; Naumann, R.; Schicks, J.M. [GeoFoschungsZentrum Potsdam, Potsdam (Germany)

2008-07-01

87

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)

88

Gas hydrates and magnetism : comparative geological settings for diagenetic analysis  

Energy Technology Data Exchange (ETDEWEB)

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.

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

89

Hydration of the Martian Surface as seen by the Imaging Spectrometer OMEGA  

OpenAIRE

Water is currently present on Mars as ice, vapor and surface hydration. Hydration is known to be adsorbed water on minerals or prisoned in their structure. It can influence the Martian water cycle as well as enable mineral alteration or exobiology. This PhD thesis studies the global and seasonal aspects of hydration using the data from the visible and near infrared imaging spectrometer OMEGA. Our work is based on the 3 µm hydration absorption feature, which has required to develop an efficie...

Jouglet, Denis

2008-01-01

90

Understanding gas hydrate dissolution  

Science.gov (United States)

In order to understand the role gas hydrates play in climate change or their potential as an energy source, we must first understand their basic behaviors. One such behavior not well understood is their dissolution and the factors that control it. Theoretically, hydrates are stable in areas of high pressure, low temperature, moderate salt concentrations, and saturated methane. Yet in nature, we observe hydrate to outcrop seafloor sediments into overlying water that is under-saturated with respect to methane. How do these hydrates not dissolve away? To address this question, we combine both field and laboratory experiments. In the field, we have collected pore-waters directly surrounding gas hydrate outcrops and measured for in situ methane concentrations. This gives us an understanding of the concentration gradients, and thus methane flux, directly from the hydrate to the surrounding environment. From these samples, we found that methane concentrations decreased further from hydrate yet are always under-saturated with respect to methane hydrate. The resulting low methane gradients were then used to calculate low dissolution rates. This result suggests that hydrates are meta-stable in the environment. What controls their apparent meta-stability? We hypothesize that surrounding oils or microbial slimes help protect the hydrate and slow down their dissolution. To test this hypothesis, we conducted a series of laboratory experiments where hydrate was formed at in situ pressure and temperature and the source gas removed; first with no oils, then with oils. Dissolved methane concentrations were then measured in surrounding fluids over time and dissolution rates calculated. To date, both methane and mixed gas hydrate (methane, ethane, and propane) have similar dissolution rates of 0.12 mM/hr. Future experiments will add oils to determine how different hydrate dissolves with such contaminants. This study will further our understanding of factors that control hydrate stability in nature.

Lapham, Laura; Chanton, Jeffrey; MacDonald, Ian; Martens, Christopher

2010-05-01

91

Mechanical properties of sand, silt, and clay containing tetrahydrofuran hydrate  

Science.gov (United States)

The mechanical behavior of hydrate-bearing sediments subjected to large strains has relevance for the stability of the seafloor and submarine slopes, drilling and coring operations, and the analysis of certain small-strain properties of these sediments (for example, seismic velocities). This study reports on the results of comprehensive axial compression triaxial tests conducted at up to 1 MPa confining pressure on sand, crushed silt, precipitated silt, and clay specimens with closely controlled concentrations of synthetic hydrate. The results show that the stress-strain behavior of hydrate-bearing sediments is a complex function of particle size, confining pressure, and hydrate concentration. The mechanical properties of hydrate-bearing sediments at low hydrate concentration (probably 50% of pore space), the behavior becomes more independent of stress because the hydrates control both stiffness and strength and possibly the dilative tendency of sediments by effectively increasing interparticle coordination, cementing particles together, and filling the pore space. The cementation contribution to the shear strength of hydrate-bearing sediments decreases with increasing specific surface of soil minerals. The lower the effective confining stress, the greater the impact of hydrate formation on normalized strength.

Yun, T.S.; Santamarina, C.J.; Ruppel, C.

2007-01-01

92

Hydration process of nuclear-waste glass: an interim report  

International Nuclear Information System (INIS)

Aging of simulated nuclear waste glass by contact with a controlled-temperature, humid atmosphere results in the formation of a double hydration layer penetrating the glass, as well as the formation of minerals on the glass surface. The hydration process can be described by Arrhenius behavior between 120 and 2400C. Results suggest that simulated aging reactions are necessary for demonstrating that nuclear waste forms can meet projected Nuclear Regulatory Commission regulations. 16 figures, 4 tables

93

Hydrated phases and pore solution composition in cementsolidified saltstone waste forms  

Directory of Open Access Journals (Sweden)

Full Text Available The mineral phases and pore solution composition of hydrated cementsolidified synthetic saltstone waste forms are quantified using thermogravimetric analysis, quantitative X-ray powder diffraction, and inductively coupled plasma atomic emission spectroscopy. Although the synthetic waste contained additional sulfate, the overall chemistry of the system suppressed the formation of sulfate-bearing mineral phases. This was corroborated by the pore solution analysis that indicated very high sulfur concentrations. After one year of hydration, the mineral phases present and the composition of the pore solution are stable, and are generally consistent with expectations based on the hydration of high volume portland cement replacement mixtures.

Philip J.

2013-07-01

94

Hydration of Portland cement with additions of calcium sulfoaluminates  

International Nuclear Information System (INIS)

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.

95

Hydration of Portland cement with additions of calcium sulfoaluminates  

Energy Technology Data Exchange (ETDEWEB)

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.

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

96

Life Origination Hydrate hypothesis (LOH-hypothesis): CH4-hydrate matrix as a necessary condition for life origin  

Science.gov (United States)

The Life Origination Hydrate hypothesis (LOHhypothesis) presents a mechanism of living matter origination from simple mineral substances within natural underground or underseabed methane-hydrate matrixes with no external energy. The mechanism is well-founded chemically, thermodynamically, and logically and is applicable to any celestial body where the corresponding temperature and mineralogical conditions are maintained at a constant level for a rather long time.

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

2012-09-01

97

Origins of hydration lubrication  

Science.gov (United States)

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.

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

2015-01-01

98

Methane Hydrate Field Program  

Energy Technology Data Exchange (ETDEWEB)

This final report document summarizes the activities undertaken and the output from three primary deliverables generated during this project. This fifteen month effort comprised numerous key steps including the creation of an international methane hydrate science team, determining and reporting the current state of marine methane hydrate research, convening an international workshop to collect the ideas needed to write a comprehensive Marine Methane Hydrate Field Research Plan and the development and publication of that plan. The following documents represent the primary deliverables of this project and are discussed in summary level detail in this final report. • Historical Methane Hydrate Project Review Report • Methane Hydrate Workshop Report • Topical Report: Marine Methane Hydrate Field Research Plan • Final Scientific/Technical Report

None

2013-12-31

99

Spectral reflectance properties (0.4-2.5 ??m) of secondary Fe-oxide, Fe-hydroxide, and Fe-sulphate-hydrate minerals associated with sulphide-bearing mine wastes  

Science.gov (United States)

Diffuse reflectance spectra of 15 mineral species commonly associated with sulphide-bearing mine wastes show diagnostic absorption bands related to electronic processes involving ferric and/or ferrous iron, and to vibrational processes involving water and hydroxyl. Many of these absorption bands are relatively broad and overlapping; however, spectral analysis methods, including continuum removal and derivative analysis, permit most of the minerals to be distinguished. Key spectral differences between the minerals are illustrated in a series of plots showing major absorption band centres and other spectral feature positions. Because secondary iron minerals are sensitive indicators of pH, Eh, relative humidity, and other environmental conditions, spectral mapping of mineral distributions promises to have important application to mine waste remediation studies.

Crowley, J.K.; Williams, D.E.; Hammarstrom, J.M.; Piatak, N.; Chou, I.-M.; Mars, J.C.

2003-01-01

100

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

101

American Strategic Minerals  

Energy Technology Data Exchange (ETDEWEB)

American Strategic Minerals brings together seven contributors in the fields of marine studies, mining engineering, earth sciences, and economics to discuss and analyze strategic minerals. The future demands of the United States upon limited sources of supply are examined and there is an analysis of alternative sources of strategic minerals from the seabed, including copper, nickel, manganese, and cobalt. The book contains an examination of the investments that the United States has made in developing countries that could affect both the national security and national economy of America in the years ahead. After a review of minerals policy in the United States, the conflicting interests that influence the President and Congress in making decisions about strategic minerals, and other dimensions of strategic minerals, are exposed to clarify both the facts and myths about supply and demand, security and danger, and high and low prices.

Mangone, G.

1984-01-01

102

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

Science.gov (United States)

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.

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

2006-12-01

103

High-pressure gas hydrates  

OpenAIRE

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...

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

2008-01-01

104

Hydrate morphology: Physical properties of sands with patchy hydrate saturation  

Science.gov (United States)

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.

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

2012-01-01

105

Evaluation of Hydrated Lime Filler in Asphalt Mixtures  

Directory of Open Access Journals (Sweden)

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.

Mohammed Abbas Hasan Al-Jumaily

2008-01-01

106

Artificial Hydration and Nutrition  

Science.gov (United States)

... should talk with the doctor about the patient's medical condition and risks and benefits of giving artificial hydration ... Care Trainer's Guide, Module 11, withholding, withdrawing therapy. In: Emanuel LL, von Gunten CJ, Ferris FD. ...

107

Hydrated vanadium pentoxide  

International Nuclear Information System (INIS)

Production methods; solubility; ion-exchange, thermal and other physico-chemical properties of hydrated vanadium pentoxide, alkali and alkaline earth metal and V2O5 hydrogel dodecavanadates are considered. Data on spectroscopy, diffraction and electrophysical methods for investigating hydrogen state, proton conductivity, complete exchange and chemical interaction processes are presented. Chemical nature of hydrated V2O5 is discussed on the basis of analysis of new results of studying the structure and properties

108

Examination of Hydrate Formation Methods: Trying to Create Representative Samples  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2011-04-01

109

Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates  

Science.gov (United States)

Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on sediments recovered during drilling in the northern Gulf of Mexico at the Atwater Valley and Keathley Canyon sites as part of the 2005 Chevron Joint Industry Project on Methane Hydrates. The tested specimens include both unremolded specimens (as recovered from the original core liner) and remolded sediments both without gas hydrate and with pore fluid exchanged to attain 100% synthetic (tetrahydrofuran) hydrate saturation at any stage of loading. Test results demonstrate the extent to which the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. We also show how permittivity and electrical conductivity data can be used to estimate the evolution of hydrate volume fraction during formation. The gradual evolution of geophysical properties during hydrate formation probably reflects the slow increase in ionic concentration in the pore fluid due to ion exclusion in closed systems and the gradual decrease in average pore size in which the hydrate forms. During hydrate formation, the increase in S-wave velocity is delayed with respect to the decrease in permittivity, consistent with hydrate formation on mineral surfaces and subsequent crystal growth toward the pore space. No significant decementation/debonding occurred in 100% THF hydrate-saturated sediments during unloading, hence the probability of sampling hydrate-bearing sediments without disturbing the original sediment fabric is greatest for samples in which the gas hydrate is primarily responsible for maintaining the sediment fabric and for which the time between core retrieval and restoration of in situ effective stress in the laboratory is minimized. In evaluating the impact of core retrieval on specimen properties, it is also important to consider how far removed hydrate-bearing samples are from hydrate stability conditions. ?? 2008 Elsevier Ltd.

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

2008-01-01

110

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

111

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

112

Antifreezes act as catalysts for methane hydrate formation from ice.  

Science.gov (United States)

Contrary to the thermodynamic inhibiting effect of methanol on methane hydrate formation from aqueous phases, hydrate forms quickly at high yield by exposing frozen water-methanol mixtures with methanol concentrations ranging from 0.6-10?wt% to methane gas at pressures from 125?bars at 253?K. Formation rates are some two orders of magnitude greater than those obtained for samples without methanol and conversion of ice is essentially complete. Ammonia has a similar catalytic effect when used in concentrations of 0.3-2.7?wt%. The structure?I methane hydrate formed in this manner was characterized by powder X-ray diffraction and Raman spectroscopy. Steps in the possible mechanism of action of methanol were studied with molecular dynamics simulations of the Ih (0001) basal plane exposed to methanol and methane gas. Simulations show that methanol from a surface aqueous layer slowly migrates into the ice lattice. Methane gas is preferentially adsorbed into the aqueous methanol surface layer. Possible consequences of the catalytic methane hydrate formation on hydrate plug formation in gas pipelines, on large scale energy-efficient gas hydrate formation, and in planetary science are discussed. PMID:25132532

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

2014-09-22

113

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)

114

Hydration of black foam films made of amphiphilic cyclodextrins.  

Science.gov (United States)

We investigate the interfacial behavior of a new type of amphiphilic cyclic oligosaccharide obtained by grafting a phospholipid onto a methylated cyclodextrin. These compounds are able to form stable black foam films, the structure of which can be determined using X-ray reflectivity. These films consist of a highly hydrated bilayer of modified cyclodextrins which are remarkably thick due to their abundant hydration core. In the present paper, we explore the influence of cyclodextrin hydration on the film structure. The hydration rate of the films is tuned by changing the cyclodextrin methylation, by binding the modified cyclodextrins to various molecules (complex formation) and by exposing the films to IR radiation. In addition, we show that the gas permeability of these phospholipidyl-cyclodextrin films is governed by their central layer of bound water, which is an efficient barrier against gas permeation. PMID:15875863

Sultanem, Caroline; Moutard, Stéphane; Benattar, Jean-Jacques; Djedaïni-Pilard, Florence; Perly, Bruno

2004-04-13

115

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.

116

Hydrating cement pastes as a complex disordered system  

Science.gov (United States)

In small-angle neutron scattering (SANS) experiments, realized on the MURN facility of the pulsed reactor IBR-2 of the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research, Dubna, the hydration processes in samples of ordinary Portland cement (OPC) and single clinker minerals are studied. The measured scattering curve contains information about the fractal behaviour of the interfaces and the size distribution of the scattering particles. Furthermore, a variation of the heavy and light water composition for the hydration water supports the selection of the observable microstructural objects. In dependence on the size distribution of the clinker grains a various time-dependent behaviour of the potential law of the scattering curve is shown. Considering the SANS results of hydrating OPC the exponents of the scattering curve in a given Q-range are varying in dependence on the hydration time and sample thickness. They lie in an interval from about -2 to -4. This is believed to be associated with fractal behaviour. A set of four hydrating C3S-samples is divided into 2 parts after an under water storage of 53 days. Then 2 samples were stored in an H2O/D2O-mixture for reducing the variety of the several hydration products by changing the neutron optical contrast. Considering the time-dependent change of the potential law of the scattering curves of hydrating C3S-samples some differences in contrast to hydrating OPC powder are visible. Within about 100 days after mixing the dry C3S powder with water the exponents of the SANS curves in the measured Q-range are higher than -3. If the hydration products of C3S are forming fractal structures then volume or mass fractals of some nanometers are shown.

Häussler, F.; Hempel, M.; Eichhorn, F.; Hempel, A.; Baumbach, H.

1995-01-01

117

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

Science.gov (United States)

Except for those occurring at the seafloor, most natural gas hydrates form in sediments and are subject to the influence of the sediment. Investigations on natural gas hydrate have found that the saturation level of gas hydrate in sediments is closely related to the sediment type: comparatively enriched in coarse sediments such as sands but poorly saturated in fine sediments such as clay. However, due to the limitation of the current geological and geophysical investigations and the rarity of the recovery of intact hydrate samples, the knowledge about sediment control on hydrate saturation in sediments is still limited, and the mechanism is not yet understood. This research investigated the possible factors involved in sediment control on hydrate saturation using an experimental approach. The experiments were carried out with both natural and artificial sediments. The natural sediments were recovered from gas hydrate reservoirs in the Nankai Trough, offshore Japan, Cascadia, offshore Vancouver Island, K-G basin, offshore India, and offshore Andaman Island. The artificial sediments were prepared with quartz powder, a representative of silicates and aluminosilicates, kaolinite and Na-montmorillonite, representatives of clay minerals, and calcite, representative of carbonate minerals. Methane hydrate was synthesized in the artificial sediments under conditions simulating the reservoir of natural gas hydrate, and its saturation levels were determined from the gas amount released from a known volume of sediment. The results indicate that particle size and mineral composition are the two main factors affecting hydrate saturation in sediments. In the range from 20 to 250 ?m, the degree of conversion of water into hydrate increases dramatically with increase in particle size, from 3% to 82%, corresponding to a pore saturation from 4% to ~ 100%. Studies also found that the sorting effect of sediment particles can also play a certain role in affecting hydrate saturation, although not as significantly as particle size. With increasing clay content, hydrate saturation decreased dramatically. When the clay content is over 40%, the degree of pore water converted to hydrate is only about 2%, corresponding to hydrate saturation lower than 3%. The NMR proton relaxation times of water confined in silica sands, show a logarithmic relationship with particle size, and it was found that the samples with higher hydrate saturation are those with longer proton relaxation times.

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

2010-12-01

118

Role of interlayer hydration in lincomycin sorption by smectite clays.  

Science.gov (United States)

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- 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

Wang, Cuiping; Ding, Yunjie; Teppen, Brian J; Boyd, Stephen A; Song, Cunyi; Li, Hui

2009-08-15

119

HYDRATE CORE DRILLING TESTS  

Energy Technology Data Exchange (ETDEWEB)

The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate formation comprised of coarse, large-grain sand in ice. Results with this core showed that the viscosity of the drilling fluid must also be carefully controlled. When coarse sand was being cored, the core barrel became stuck because the drilling fluid was not viscous enough to completely remove the large grains of sand. These tests were very valuable to the project by showing the difficulties in coring permafrost or hydrates in a laboratory environment (as opposed to a field environment where drilling costs are much higher and the potential loss of equipment greater). Among the conclusions reached from these simulated hydrate coring tests are the following: Frozen hydrate core samples can be recovered successfully; A spring-finger core catcher works best for catching hydrate cores; Drilling fluid can erode the core and reduces its diameter, making it more difficult to capture the core; Mud must be designed with proper viscosity to lift larger cuttings; and The bottom 6 inches of core may need to be drilled dry to capture the core successfully.

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

2002-11-01

120

Mineral resource of the month: vermiculite  

Science.gov (United States)

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.

Potter, M.J.

2008-01-01

121

A new clathrate hydrate structure  

International Nuclear Information System (INIS)

On the basis of 2H and 129Xe NMR measurements and X-ray and neutron powder diffraction results, the authors report a new hexagonal hydrate structure requiring both large and small guest molecules to stabilize the structure. This hydrate is expected to be isostructural with the hexagonal clathrasil dodecasil-1H. As for the cubic clathrate hydrates, the new hydrate structure may occur naturally. (author)

122

An examination of kernite (Na2B4O6(OH)2·3H2O) using X-ray and electron spectroscopies: quantitative microanalysis of a hydrated low-Z mineral.  

Science.gov (United States)

Mineral borates, the primary industrial source of boron, are found in a large variety of compositions. One such source, kernite (Na2B4O6(OH)2·3H2O), offers an array of challenges for traditional electron-probe microanalysis (EPMA)-it is hygroscopic, an electrical insulator, composed entirely of light elements, and sensitive to both low pressures and the electron beam. However, the approximate stoichiometric composition of kernite can be analyzed with careful preparation, proper selection of reference materials, and attention to the details of quantification procedures, including correction for the time dependency of the sodium X-ray signal. Moreover, a reasonable estimation of the mineral's water content can also be made by comparing the measured oxygen to the calculated stoichiometric oxygen content. X-ray diffraction, variable-pressure electron imaging, and visual inspection elucidate the structural consequences of high vacuum treatment of kernite, while Auger electron spectroscopy and X-ray photoelectron spectroscopy confirm electron beam-driven migration of sodium and oxygen out of the near-surface region (sampling depth ? 2 nm). These surface effects are insufficiently large to significantly affect the EPMA results (sampling depth ? 400 nm at 5 keV). PMID:21892991

Meier, Douglas C; Davis, Jeffrey M; Vicenzi, Edward P

2011-10-01

123

Wet hydrate dissolution plant  

Directory of Open Access Journals (Sweden)

Full Text Available The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE, Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. Main goal was increasing the detergent zeolite production capacity. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution. Wet hydrate dissolution is now fully continuous, which is important for maintaining zeolite production quality, as well as for simplifying production. The wet hydrate production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start-up, and repairs. By installing additional process equipment (centrifugal pumps and dissolving reactors technological bottlenecks were overcome, and by adjusting NaOH tanks and dissolving reactors, the capacities of the process equipment was fully utilized.

Stankovi? Mirjana S.

2003-01-01

124

Geophysical implications of reduction in thermal conductivity due to hydration  

Science.gov (United States)

Water dramatically affects physical properties of rocks, minerals, and melts. The importance of hydration to mantle processes is exemplified by modeling efforts regarding its effect on mantle viscosity. Our new measurements using the highly accurate (± 2%) laser-flash technique shows that hydration lowers the lattice component of thermal diffusivity (D) for calcic and Fe-Mg garnets, and glasses (silica and BK7). Protonation is implicated because the degree of change is correlated with OH- content (X), regardless of composition, structure, or degree of crystallinity, and H is the only impurity of any significance in fused silica. Hydration depresses D above the glass transition of BK7 glass, suggesting that melts respond likewise. For garnets, d(lnD)/dX = -0.003 %/ppm H2O. For olivine and quartz, D is constant, but thermal conductivity (k = ? CPD) decreases because hydration generally lowers density (?) and negligibly changes heat capacity (CP). Our result is consistent with previous studies on the effect of cation substitutions, which lower k through creation of disorder, and with theoretical models of vibrational diffusion of heat. Reduction of thermal transport by hydration is geophysically significant; specifically, it suggests that hydration leads to heat retention, promoting convective instabilities and melting. The effect is particularly relevant to melting processes because hydration also lowers the melting temperature and increases the field of melt stability. Such positive feedback could lead to runaway melting. Melt generation at subduction zones may be a possible example of such interplay. The effect of water on heat transport will also augment hydrolytic weakening. Our results disfavor enrichment of transition zone in water relative to the upper mantle; not only does hydration generally decrease ?, so that deeper, wetter layers contribute to gravitational instability, but moreover H enrichment lowers k, contributing to thermal instability.

Branlund, J. M.; Hofmeister, A. M.; Pertermann, M.; Whittington, A. G.

2006-12-01

125

Hydration of the cement 2; Semento no suiwa 2  

Energy Technology Data Exchange (ETDEWEB)

The strength development in the belite cement changes the elucidation of suppressed mechanism to AFm from AFt with the purpose Ichimura change. Gypsum quantity and sulfuric acid alkali-dope quantity were replaced with synthesis alite and C{sub A}, and ordinary temperature and half quantity by thermal analysis of aluminate hydrate by ages seventh at 80 degrees C, alite by XRD and measurement of C{sub 3}A reaction rate were carried out. It was found that the addition of AFm was slower, as the gypsum quantity is more abounding. And, the clear effect by the curing temperature was not obtained. Morioka et al. clarified anhydrous gypsum, hydration reaction of constituent mineral of expanding agent which consists of the free lime, phase constitution of the hydrate in each age mainly on aruin which is Culciumsulfaaluminate by the precise measurement by X-ray diffraction. The reaction rate hydration reaction progressed at the order of free lime, anhydrous gypsum, aruin, and amorphous gel phase was created from the age initial stage, and it also clarified the chemical composition. As, Morioka et al. examined C{sub 3}A and hydration reaction of expanding cement in the gypsum dihydrate coexistence in order to clarify the hydration reaction of expanding material by the portland cement presence. As the result, that it was remarkably promoted clarified by both coexistence. Kano et al. used 3 kinds of super hardening cement of aruin system, C{sub 1}2A{sub 7} glass system, C{sub 1}1A{sub 7-}CaF{sub 2} system. The following were related: Phase constitution model and heat of hydration, bound water quantity as pot life changes. The strength of the super hardening cement was estimated there from heat of hydration and bound water quantity. (translated by NEDO)

Hanehara, Shunsuke [Chichibu Onoda Cement Corp., Yamaguchi (Japan)

1998-09-10

126

Effect of CO2 hydrate formation on seismic wave velocities of fine-grained sediments  

Science.gov (United States)

study examines the effect of gas hydrate formation on seismic wave velocities of fine-grained sediments. Synthesis of gas hydrates in fine-grained sediments has proved to be challenging, and how hydrate formation would affect the seismic wave velocities and stiffness of clay-rich sediments has not yet been fully understood. In this study, CO2 hydrate was synthesized in remolded and partially water-saturated clayey silt sediments that were originally cored from a hydrate occurrence region in the Ulleung Basin, East Sea, offshore Korea. After achieving excess water conditions, compressional wave and shear wave velocities were measured for different hydrate saturations and under different vertical effective stresses. The results reveal that the compressional wave velocity VP and shear wave velocity VS increase, and the stress-dependency of VP and VS decreases as the hydrate saturation SH increases from 0% to ~60%. In particular, the VS-SH trend lies between the grain-cementing model and the load-bearing model, suggesting that gas hydrate formation in clayey silt sediments causes weak cementation from a hydrate saturation less than ~28%. The weak cementation in fine-grained sediments can be explained by the breakage of hydrate bonds that are cementing grains during sediment compression and/or the innate weakness in bonding between hydrate crystals and fine mineral grains owing to the presence of unfrozen water films on clay mineral surfaces. In addition, it is found that at low SH, the cementation effect on VP is masked by the high stiffness of pore-filling phases, but it becomes pronounced at SH greater than 47%.

Kim, Hak-Sung; Cho, Gye-Chun; Kwon, Tae-Hyuk

2013-06-01

127

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

Science.gov (United States)

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.

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

2014-11-01

128

Molecular simulations of CO2 and mixed CH4-CO2 hydrates intercalated on smectites.  

Science.gov (United States)

Natural gas hydrates (NGH) are crystalline compounds consisting of methane molecules encaged in cavities of a hydrogen-bonded network of water molecules. Gas hydrates have a general formula X?nH2O, where X is the guest molecule within a water cage, and n is the hydration number per guest molecule. The crystal structure sI consists of 46 water molecules per unit cell, forming two dodecahedron (small 512) and six tetradecahedron (large 51262) cages and is formed when small guest molecules such as methane or carbon dioxide are trapped. Considerable amounts of methane hydrates can be found in permafrost regions and sediments of the ocean floor in outer continental margin regions where medium pressures, low temperatures and high methane gas concentration in water can be reached. Gas hydrates are important because hydrate decomposition would cause the methane release into atmosphere causing great impact on Earth's climate. On the other hand, these NGH are seen as a potential major energy resource. The recent increase in anthropogenic CO2 gas released to the atmosphere and its contribution to global warming, makes necessary to investigate new ways of CO2 storage. The possibility of replacing natural gas by CO2 from NGH has been investigated. There are thermodynamic evidences that support the replacement in hydrate at appropriate conditions. The comparison of their hydrate phase equilibrium conditions suggests the occurrence of a transition zone between both hydrate equilibrium curves where CO2 hydrates can exist while CH4 hydrates dissociate into methane gas and water. Any further investigation of the mixed CH4-CO2 gas hydrate properties could lead to major breakthroughs in the fields of unconventional resource production and carbon sequestration. Clay minerals are major constituents of ocean sediments, the study of interactions between these minerals with hydrates on the seafloor can be useful to determine variations on hydrate stability field, and to know the properties and behavior of hydrate-smectite complex. Characterization and better understanding of those deposits are necessary to develop CO2 storage as hydrates by methane replacement. Swelling clays usually contains multiple planes of weakly bonded H2O in the interlayer between the 2:1 (silicate) layers. Koster van Groos et al. (2009) synthesized a smectite-methane hydrate intercalate with d(001)=2.2 nm indicating the presence of one unit cell of methane hydrate crystal intercalated between the 2:1 layers of smectite. Due to the complexity of experimental studies with hydrates, Computational Mineralogy can be very helpful. In this study we compare the behavior of CO2 and mixed CH4-CO2 hydrates intercalated in montmorillonite and beidellite. Our results are in agreement with the d(001)=2.2 nm in both hydrates intercalated as crystal lattice. However, comparing mean square displacement (MSD) profiles from molecular dynamics simulations of H2O molecules in the hydrates, we found that hydrate crystal MSD show a typical solid profile without diffusion, while in the intercalates there is more diffusion of water molecules, hence CO2 and mixed CH4-CO2 hydrate structure is more flexible and stable in the smectite-hydrate complex. Authors are thankful to RNM-3581 CADHYS Project.

Martos-Villa, Rubén; Sainz-Díaz, C. Ignacio; Mata Campo, M. Pilar

2013-04-01

129

Electronic structure calculations of calcium silicate hydrates  

International Nuclear Information System (INIS)

Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO3) and xonotlite (Ca6Si6O17(OH)2), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases

130

Seismic model of Mars: Effects of hydration  

Science.gov (United States)

The arguments according to which the Martian minerals are assumed to contain large amount of water in the mantle minerals are given. As for the Earth, these minerals may constitute about 60 wt% of the Martian mantle, and can be considered as main components in their zones. In the mantle of the Earth the molecular concentration of Fe is about 10%, and for the mantle of Mars - about 20%. Taking into account twofold increase of Fe in Martian silicates in comparison with the terrestrial minerals, we have extrapolated the available partial experimental data of the hydration effect on the compressional and shear velocities of seismic waves in forsterite (olivine) and its high pressure phases - wadsleyite and ringwoodite for Martian conditions. The presence of water in the mantle of Mars may lead to the noticeable widening of the olivine-wadsleite phase transition zone, thus the determination of the olivine-wadsleite phase transition width by seismological methods could get a direct indication on the presence of water in the mantle of Mars. To find out real estimates of water content in the mantle of Mars is a task for the future seismic missions. The results of this article are important for InSight mission that will land a geophysical station on Mars in 2016.

Zharkov, V. N.; Gudkova, T. V.

2014-12-01

131

A study on gas hydrate  

Energy Technology Data Exchange (ETDEWEB)

Sufficient documents were reviewed to understand solid components of water and gaseous hydrocarbon known as gas hydrates, which represent an important potential energy resource of the future. The review provides us with valuable information on crystal structures, kinetics, origin and distribution of gas hydrates. In addition, the review increased our knowledge of exploration and development methods of gas hydrates. Large amounts of methane, the principal component of natural gas, in the form of solid gas hydrate are found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost. Natural gas hydrates are stable in some environments where the hydrostatic pressure exerted by overlying water column is sufficient for hydrate formation and stability. The required high pressures generally restrict gas hydrate to sediments beneath water of approximately 400 m. Higher sediment temperatures at greater subbottom depths destabilize gas hydrates. Based on the pressure- temperature condition, the outer continental margin of East Sea where water depth is deep enough to form gas hydrate is considered to have high potential of gas hydrate accumulations. (author). 56 refs., tabs., figs.

Yoo, Byoung Jae; Jung, Tae Jin; Sunwoo, Don [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1996-12-01

132

[Synthetic mineral fibers].  

Science.gov (United States)

The group of man-made mineral fibres includes slagwool, glasswool, rockwool, glass filaments and microfibres, as well as refractory ceramic fibres. The toxicity of mineral fibres is determined by several factors such as the diameter (< or = 3-3.5 microns) and the length of the fibres (< 100 microns), their biopersistence, which is much shorter for man-made mineral fibres than for asbestos fibres, their physicochemical structure and surface properties, and the exposure level. The chemical composition of the various types of man-made mineral fibres depends directly on the raw material used to manufacture them. While naturally occurring fibres are crystalline in structure, most man-made mineral fibres are amorphous silicates combined with various metal oxides and additives. Observations using intracavitary administration have provided evidence that some types of man-made mineral fibres are bioactive in cellular and animal experiments and may induce lung tumours and mesothelioma. It is difficult to extrapolate these results to humans since they bypass inhalation, deposition, clearance and translocation mechanisms. Inhalation studies show more realistic results but differences are observed between animal species regarding their sensibility to tumours. There is no firm evidence that exposure to various wools is associated with lung fibrosis, pleural lesions or nonspecific respiratory disease in humans. A possible exception may be mentioned for refractory ceramic fibres. A slightly elevated standard mortality ratio for lung cancer has been documented in large cohorts of workers (USA, Europe and Canada) exposed to man-made mineral fibres, especially in the early technological phase. It is not possible to determine from these data whether the risk of lung cancer is due to the man-made mineral fibres themselves, in particular due to the lack of data on smoking habits. No increased risk of mesothelioma has been demonstrated in these cohorts. Epidemiological data are insufficient at this time concerning neoplastic diseases in refractory ceramic fibres. PMID:10231901

Boillat, M A

1999-03-27

133

Hydration of oxo anions  

OpenAIRE

The structure and dynamics of several hydrated oxo anions were studied using multiple methodologies. Aqueous solutions of sulfate, sulfite, thiosulfate, peroxysulfate, selenite, selenate, hypochlorite, chlorite, chlorate, perchlorate, bromate, iodate and periodate salts were studied using large angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The thiosulfate, selenite and selenate salts were also studied using double difference infrared spectros...

Eklund, Lars

2014-01-01

134

Methane Clathrate Hydrate Prospecting  

Science.gov (United States)

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

Duxbury, N.; Romanovsky, V.

2003-01-01

135

Hydration-dependent dynamic crossover phenomenon in protein hydration water  

Science.gov (United States)

The characteristic relaxation time ? of protein hydration water exhibits a strong hydration level h dependence. The dynamic crossover is observed when h is higher than the monolayer hydration level hc=0.2-0.25 and becomes more visible as h increases. When h is lower than hc, ? only exhibits Arrhenius behavior in the measured temperature range. The activation energy of the Arrhenius behavior is insensitive to h, indicating a local-like motion. Moreover, the h dependence of the crossover temperature shows that the protein dynamic transition is not directly or solely induced by the dynamic crossover in the hydration water.

Wang, Zhe; Fratini, Emiliano; Li, Mingda; Le, Peisi; Mamontov, Eugene; Baglioni, Piero; Chen, Sow-Hsin

2014-10-01

136

Clathrate hydrates for ozone preservation.  

Science.gov (United States)

We report the experimental evidence for the preservation of ozone (O(3)) encaged in a clathrate hydrate. Although ozone is an unstable substance and is apt to decay to oxygen (O(2)), it may be preserved for a prolonged time if it is encaged in hydrate cavities in the form of isolated molecules. This possibility was assessed using a hydrate formed from an ozone + oxygen gas mixture coexisting with carbon tetrachloride or xenon. Each hydrate sample was stored in an air-filled container at atmospheric pressure and a constant temperature in the range between -20 and 2 degrees C and was continually subjected to iodometric measurements of its fractional ozone content. Such chronological measurements and structure analysis using powder X-ray diffraction have revealed that ozone can be preserved in a hydrate-lattice structure for more than 20 days at a concentration on the order of 0.1% (hydrate-mass basis). PMID:20707330

Muromachi, Sanehiro; Ohmura, Ryo; Takeya, Satoshi; Mori, Yasuhiko H

2010-09-01

137

Surface Geochemistry of the Clay Minerals  

Science.gov (United States)

Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent structural charge of clay mineral particles, which endow them with significant surface reactivity. Unraveling the surface geochemistry of hydrated clay minerals is an abiding, if difficult, topic in earth sciences research. Recent experimental and computational studies that take advantage of new methodologies and basic insights derived from the study of concentrated ionic solutions have begun to clarify the structure of electrical double layers formed on hydrated clay mineral surfaces, particularly those in the interlayer region of swelling 2:1 layer type clay minerals. One emerging trend is that the coordination of interlayer cations with water molecules and clay mineral surface oxygens is governed largely by cation size and charge, similarly to a concentrated ionic solution, but the location of structural charge within a clay layer and the existence of hydrophobic patches on its surface provide important modulations. The larger the interlayer cation, the greater the influence of clay mineral structure and hydrophobicity on the configurations of adsorbed water molecules. This picture extends readily to hydrophobic molecules adsorbed within an interlayer region, with important implications for clay-hydrocarbon interactions and the design of catalysts for organic synthesis.

Sposito, Garrison; Skipper, Neal T.; Sutton, Rebecca; Park, Sung-Ho; Soper, Alan K.; Greathouse, Jeffery A.

1999-03-01

138

Hydrate Monitoring using Capacitive Sensors  

OpenAIRE

Gas hydrates are of particular interest in petroleum industry since their formation during oil-production can be a major risk factor. Gas hydrates can block pipelines, interrupt production, and in worst case even cause bursting flow lines. There are a few strategies available to monitor the hydrocarbon flow in pipelines in order to give an early warning system against hydrate formation. A potential technique is to monitor changes in the dielectric properties of the flow, and relate these to h...

Bayati, Zahra

2013-01-01

139

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

Science.gov (United States)

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.

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

2014-11-01

140

Mineral Identification  

Science.gov (United States)

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.

Pratte, John

141

Window contamination on Expose-R  

Science.gov (United States)

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.

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

142

Novel observations on the massive Barkley Canyon hydrates  

Science.gov (United States)

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.

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

2006-12-01

143

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)

144

Percutaneous Absorption of Haloacetonitriles and Chloral Hydrate and Simulated Human Exposures  

OpenAIRE

Disinfection-by-products (DBPs) have long been a human health concern and many are known carcinogens and teratogens. Skin is exposed to DBPs in water through bathing and swimming; however, dermal uptake of many DBPs has not been characterized. The present studies were initiated to measure the permeation coefficients (Kp) for haloacetonitriles (HANs) and chloral hydrate (CH), important cytotoxic DBPs. The Kp values measured using fully hydrated dermatomed torso skin at 37 °C for the HANs rang...

Trabaris, Maria; Laskin, Jeffrey D.; Weisel, Clifford P.

2012-01-01

145

Animated molecular dynamics simulations of hydrated caesium-smectite interlayers  

Directory of Open Access Journals (Sweden)

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.

Sposito Garrison

2002-09-01

146

Flow assurance intervention, hydrates remediation  

Energy Technology Data Exchange (ETDEWEB)

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)

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

2012-07-01

147

Possible Crustal Boundary Exposed at Lunar Copernicus Crater  

Science.gov (United States)

Mineral distribution and geology of lunar Copernicus Crater studied with VIS-NIR reflectance spectra of Kaguya Multiband Imager (MI) indicate that a crustal boundary may be exposed at the Copernicus Crater.

Arai, T.; Ohtake, M.; Yamamoto, A.; Sugihara, T.; Hiroi, T.; Nakamura, R.; Namiki, N.; Wada, K.; Yamamoto, S.; Matsunaga, T.; Haruyama, J.

2011-03-01

148

Le concept d'eau ice-like: hydratation-déshydratation des sels, hydroxydes, zeolites, argiles et matières organiques vivantes ou inertes  

Science.gov (United States)

The concept of ice-like water is applied to the prediction of hydration-dehydration reactions among clay minerals, hydroxides, hydrated salts, and living or inert organic matter, which appear to be very sensitive indicators of the climate of soil genesis and conditions o bunal diagenesis Adsorption-desorption under temperature or pressure depends on the thermodynamic properties (entropy, heal capacity and volume) of structural water retained in organic or mineral compounds, which are similar to those of the dense ice polymorphs.

Tardy, Yves; Mercury, Lionel; Roquin, Claude; Vieillard, Philippe

1999-09-01

149

Hydrate nickel vanadates  

International Nuclear Information System (INIS)

Composition of equilibrium solid phases forming within LiVO3-NiSO4-H2SO4-LiOH-H2O system is determined using chemical and X-ray phase analyses and IR spectroscopy. Here belong nickel dodecavanadate NiV12O31·11H2O, nickel pentavanadate Ni(V5O13)2·13H2O, nickel decavanade (NIOH)6·V10O28·25H2O, nickel metavanadate (Ni(VO3)2·6H2O, nickel orthovanadate Ni3(VO4)2·5H2O. Thermal and some structural properties of nickel metavanadate crystal hydrate were studied. 12 refs.; 1 fig.; 1 tab

150

Dynamics of Protein Hydration Water  

CERN Document Server

We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range including the so-called No Man's Land (160 - 235 K). The obtained results prove the bimodality of the hydration shell dynamics and are discussed in the context of the highly-debated fragile-to-strong transition of water.

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

2014-01-01

151

Hydration of alite containing alumimium  

OpenAIRE

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 ...

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

2009-01-01

152

Clay Minerals  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2014-03-14

153

Hydration of the cement 3; Semento no suiwa 3  

Energy Technology Data Exchange (ETDEWEB)

Hoshino et al. proposed hydration model in which the hydrate (diffusion layer) was formed on the basis of the data of hydration heat generation rate on both surfaces of alite and limestone fine powder. Yoshioka et al. showed that the relation between mixing method of the cement and afterwards bleeding behavior differed by the type (alite, belite) of the cement constituent mineral. Nishikawa et al. introduced the new test method for measuring tension and compression strength of the mortar at the good accuracy. In continueing, on the basis of the test data, tension of the mortar, aggregate amount on compression strength and effects of the silica fume mixing, etc. were reported. Asaga et al. introduced the X-ray diffraction method which measured reaction quantity and calcium hydroxide formation of the alite in cement paste continuously. Numata et al. showed that addition of N, N - dimethylformamide (DMF) in selective dissolution and compensation of bound water in insoluble improved the measurement accuracy of hydration rate of blast furnace slag retained material. (translated by NEDO)

Takahashi, Toshiyuki [Ube Industries Ltd., Yamaguchi (Japan)

1998-09-10

154

In situ DMSO hydration measurements of HTS compound libraries.  

Science.gov (United States)

Compounds used in high throughput screening (HTS) are typically dissolved in DMSO. These solutions are stored automation-friendly racks of wells or tubes. DMSO is hygroscopic and quickly absorbs water from the atmosphere. When present in DMSO compound solutions, water can accelerate degradation and precipitation. Understanding DMSO hydration in an HTS compound library can improve storage and screening methods by managing the impact of water on compound stability. A non-destructive, acoustic method compatible with HTS has been developed to measure water content in DMSO solutions. Performance of this acoustic method was compared with an optical technique and found to be in good agreement. The accuracy and precision of acoustic measurements was shown to be under 3% over the tested range of DMSO solutions (0% to 35% water by volume) and insensitive to the presence of HTS compounds at typical storage concentrations. Time course studies of hydration for wells in 384-well and 1536-well microplates were performed. Well geometry, fluid volume, well position and atmospheric conditions were all factors in hydration rate. High rates of hydration were seen in lower-volume fills, higher-density multi-well plates and when there was a large differential between the humidity of the lab and the water content of the DMSO. For example, a 1536-well microplate filled with 2microL of 100% DMSO exposed for one hour to a laboratory environment with approximately 40% relative humidity will absorb over 6% water by volume. Understanding DMSO hydration rates as well as the ability to reverse library hydration are important steps towards managing stability and availability of compound libraries. PMID:16178808

Ellson, R; Stearns, R; Mutz, M; Brown, C; Browning, B; Harris, D; Qureshi, S; Shieh, J; Wold, D

2005-09-01

155

Hydration of mineral surfaces probed at the molecular level.  

Science.gov (United States)

By employing the nonlinear optical, interface selective experiment of sum frequency spectroscopy together with independent ab initio and density functional theory calculations, we determine the functional species of a corundum (001) surface: doubly coordinated OH groups which differ in their bond tilt angles. The interaction of the functional species with the adjacent water molecules is also observed. In a large pH range around the point of zero charge, the interaction is not controlled electrostatically but by hydrogen bonding. The functional species' tilt angles are crucial parameters, determining whether the species act as hydrogen bond donors or acceptors. PMID:18980345

Flörsheimer, Mathias; Kruse, Klaus; Polly, Robert; Abdelmonem, Ahmed; Schimmelpfennig, Bernd; Klenze, Reinhardt; Fanghänel, Thomas

2008-12-01

156

Hydrogeochemical and structural controls on heterogenous gas hydrate distribution in the K-G basin offshore SE India  

Energy Technology Data Exchange (ETDEWEB)

The distribution and abundance of gas hydrate deposits in marine sediments is typically disseminated within fine-grained sediments at low concentrations or occurs in massive amounts along faults and fractures within coarser-grained lithologies. Occurrences of gas hydrates are often difficult to detect using traditional remote sensing methods. This paper discussed a scientific expedition conducted to establish the structural and lithological controls on gas hydrate distribution and assess the resource potential and environmental hazards of gas hydrate deposits located off the coast of southeastern India. Drilling cores were taken from 10 sites exhibiting variable geologic conditions and bottom simulating reflector (BSR) characteristics in the K-G basin located in the Indian Ocean. Major, minor, and trace element concentrations and isotope ratios were analyzed in order to determine diagenetic and metabolic reactions; fluid migration; fluid and gas sources; fluid flow pathways; and the spatial distribution of the hydrates. Pore fluid analyses were conducted to measure salinity and mineral concentrations. Results of the analyses showed that the occurrence and concentrations of the gas hydrates varied between sites. Hydrates occurred between 50 mbsf, and typical pore space occupancies were less than 2 per cent. Massive occurrences of the hydrates were controlled by high-angle fractures in clay and silt sediments as well as by lithology at diffused sites. Maximum pore space occupancy was 67 per cent. Results of the study will be used to developed a regional gas hydrate reservoir model linking geology, geochemistry, and subsurface hydrology of the basin. 22 refs., 7 figs.

Solomon, E.A.; Kastner, M.; Robertson, G. [Scripps Inst. of Oceanography, La Jolla, CA (United States); Spivack, A.J. [Rhode Island Univ., Narragansett, RI (United States). Graduate School of Oceanography; Torres, M. [Oregon State Univ., Corvallis, OR (United States); Borole, D.V. [National Inst. of Oceanography, Goa (India); Das, H.C. [Oil India Ltd., Assam (India)

2008-07-01

157

Deep water cycle: Mantle hydration  

Science.gov (United States)

The fate of water that enters the mantle within subducting slabs is unclear. Laboratory experiments indicate that subducted crust can transport large amounts of water into the deep Earth, and the lower mantle may become more hydrated over time.

Nishi, Masayuki

2015-01-01

158

Perspectives on Hydrate Thermal Conductivity  

Directory of Open Access Journals (Sweden)

Full Text Available In this review, the intriguing, anomalous behaviour of hydrate thermal conductivity will be described, and progress in performing experimental measurements will be described briefly. However particular attention shall be devoted to recent advances in the development of detailed theoretical understandings of mechanisms of thermal conduction in clathrate hydrates, and on how information gleaned from molecular simulation has contributed to mechanistic theoretical models.

Niall J. English

2010-12-01

159

Hydration in soccer: a review  

OpenAIRE

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. Th...

Monteiro Cristiano Ralo; Guerra Isabela; Barros Turíbio Leite de

2003-01-01

160

Hydration water and microstructure in calcium silicate and aluminate hydrates  

Energy Technology Data Exchange (ETDEWEB)

Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C{sub 3}S, C{sub 2}S) and aluminates (C{sub 3}A, C{sub 4}AF) were studied by quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and near-infrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm{sup -1} monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the {sup 1}H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small angle neutron scattering (USANS) and wide angle x-ray scattering (WAXD) that characterize how additives affect both the hydrated microstructure development and the original grain size. In particular, SPs alter the morphology of the hydrated phases, which no longer grow with the classic fibrillar structure on the grain surface, but nucleate in solution as globular structures. All this information converges in a quantitative, and at molecular level, description of the mechanisms involved in the setting process of one of the materials most widely used by human beings.

Fratini, Emiliano [Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3-Sesto Fiorentino, I-50019 Florence (Italy); Ridi, Francesca [Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3-Sesto Fiorentino, I-50019 Florence (Italy); Chen, Sow-Hsin [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Baglioni, Piero [Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3-Sesto Fiorentino, I-50019 Florence (Italy)

2006-09-13

161

Hydration water and microstructure in calcium silicate and aluminate hydrates  

Science.gov (United States)

Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C3S, C2S) and aluminates (C3A, C4AF) were studied by quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and near-infrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm-1 monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the 1H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small angle neutron scattering (USANS) and wide angle x-ray scattering (WAXD) that characterize how additives affect both the hydrated microstructure development and the original grain size. In particular, SPs alter the morphology of the hydrated phases, which no longer grow with the classic fibrillar structure on the grain surface, but nucleate in solution as globular structures. All this information converges in a quantitative, and at molecular level, description of the mechanisms involved in the setting process of one of the materials most widely used by human beings.

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

2006-09-01

162

Heavily Hydrated Salts on Europa  

Science.gov (United States)

Telescopic and spacecraft observations indicate the ubiquitous presence of water ice on the surface of Europa. Additional components include hydrogen peroxide and possibly both sulfur dioxide and carbon dioxide. Irradiation by charged particles and possible communication with a convecting interior may also have led to the creation and exposure of additional surface compounds. Disrupted terrains on Europa, including linea, chaos regions, impact basins and significant portions of the trailing hemisphere reveal spectral evidence for an additional component. Near-infrared reflectance spectroscopy from Galileo NIMS (Near-Infrared Mapping Spectrometer) indicates that this material is highly hydrated, as evidenced by strongly asymmetric absorption features attributed to waters of hydration at 1.5 and 2.0 microns. New laboratory studies of heavily hydrated salts demonstrate that as the number of waters of hydration increases, the similarity to spectral observations of Europa becomes more pronounced. We have conducted cryogenic reflectance spectroscopy of the highly hydrated sulfate compounds epsomite, mirabilite, hexahydrite, bloedite and magnesium sulfate dodecahydrate, measured at temperatures relevant to the surface of Europa ( 100K). We present results of these studies, along with modeling results which constrain relative abundances of hydrated materials on Europa. Thus far, no material studied can by itself account for the observed spectral character of the reddish, disrupted Europan terrains. However, there are possible mixtures of materials which give reasonable approximations to the Europa observations, subject to considerations of uniqueness and both physical and chemical viability.

Dalton, J. B.

2005-08-01

163

Mutagenesis of Bacteria by Fibrous or Clay Minerals  

OpenAIRE

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...

Naoto Yoshida; Tadahumi Naka; Kazuyoshi Ohta

2004-01-01

164

Characterization of Methane Hydrate Growth from Aqueous Solution by Raman Spectroscopy  

Science.gov (United States)

We observed the growth of methane hydrate from aqueous solution in fused silica capillaries near room temperature (RT) in two different experiments. In the first, we sealed methane together with ~2 wt% Na2SO4 solution in a fused silica capillary (0.3x0.3 mm cross-section with 0.05x0.05 mm cavity, and ~6 cm long), using the method of Chou et al. (2008, Geochim. Cosmochim. Acta, 72, 2517). The hydrate, liquid, and vapor coexist at ~23 °C and ~36.5 MPa. The behavior of two methane bubbles, one of which was enclosed by a hydrate crystal and the other near a small hydrate crystal, was monitored. These two bubbles are the only methane sources near the hydrate crystals. The system was slowly cooled to RT (~21 °C), and images were recorded continuously for a period of ~1.5 hours, together with temperature and time information. The images show the exposed bubble decreased in size, while both of the hydrate crystals increased in size, which was caused by the transfer of methane in solution. According to our previous report (Fig. 8 of Lu et al., 2008, Geochim. Cosmochim. Acta, 72, 412), the concentrations of methane in the solution near the exposed bubble are higher than those near the hydrate crystals. Most of the dissolved methane, transferred down the concentration gradient, was consumed and encaged in the nearby crystal, with only a small fraction of methane being consumed by the more distant crystal. Eventually, the exposed vapor bubble was totally consumed, but the bubble shielded by the hydrate crystal remained. This shows hydrate can grow from dissolved methane in the solution far away from free gas. In the 2nd experiment, we sealed methane, together with pure H2O and glass beads (0.04 to 0.07 mm in dia.), in a fused silica capillary (0.3 mm OD, 0.1 mm ID, and ~6 cm long) using the method cited above. We separated the vapor phase from the solution and glass beads by centrifuging the sealed capsule, then imposed a T gradient to the sample by cooling the solution end of the capsule to ~0 °C. It is difficult to recognize the nucleation and growth of hydrate crystals under a microscope, but Raman spectroscopy was used to identify and map the distribution of hydrate crystals along the capsule. Near the original vapor-aqueous phase boundary (V-A B), Raman signals show 100% methane hydrate. However, the lack of dissolved methane in the solution further away from the V-A B limited the growth of hydrate, as indicated by the increase in water/hydrate ratio when the Raman spectrum, which combines signals from both water and hydrate, was collected further away from the V-A B. We are investigating other possible ways to map the distribution of hydrate crystals around the glass beads, including x-ray computed tomography, to understand the nature of methane hydrate crystals that grow around grains in marine sediments from pore water. These observations will improve our ability to interpret the geophysical responses (e.g., electric and acoustic signals) obtained from hydrate-bearing sediments in the field.

Chou, I.; Lu, W.; Yuan, S.; Li, J.; Burruss, R. C.

2009-12-01

165

Ukraine’s prospects in development of marine mineral deposits  

OpenAIRE

It is shown that the known reserves of ma¬rine minerals, including polymetallic nodules hydrates, marine sapropels, etc., will last the humanity for thousands of years. International cooperation and broad cooperation of companies and enterprises of maritime mining are needed to conduct the search, along with research and operation of deep mining complexes. This will allow us to prepare for the commercial development of marine deposits of mineral and energy resources in the near future.

Sukach, M.

2013-01-01

166

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

167

Imaging hydrated microbial extracellular polymers: Comparative analysis by electron microscopy  

Energy Technology Data Exchange (ETDEWEB)

Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigating microscale associations. Electron microscopy has been used extensively for geomicrobial investigations and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions using conventional electron microscopy approaches of imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding nature of interactions between microbial extracellular polymers and their environment.

Dohnalkova, A.C.; Marshall, M. J.; Arey, B. W.; Williams, K. H.; Buck, E. C.; Fredrickson, J. K.

2011-01-01

168

Gas hydrate that breaches the sea floor on the continental slope of the Gulf of Mexico  

Science.gov (United States)

We report observations that concern formation and dissociation of gas hydrate near the sea floor at depths of ˜540 m in the northern Gulf of Mexico. In August 1992, three lobes of gas hydrate were partly exposed beneath a thin layer of sediment. By May 1993, the most prominent lobe had evidently broken free and floated away, leaving a patch of disturbed sediment and exposed hydrate. The underside of the gas hydrate was about 0.2 °C warmer than ambient sea water and had trapped a large volume of oil and free gas. An in situ monitoring device, deployed on a nearby bed of mussels, recorded sustained releases of gas during a 44 day monitoring period. Gas venting coincided with a temporary rise in water temperature of 1 °C, which is consistent with thermally induced dissociation of hydrate composed mainly of methane and water. We conclude that the effects of accumulating buoyant force and fluctuating water temperature cause shallow gas hydrate alternately to check and release gas venting.

MacDonald, I. R.; Guinasso, N. L., Jr.; Sassen, R.; Brooks, J. M.; Lee, L.; Scott, K. T.

1994-08-01

169

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

Science.gov (United States)

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

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

2008-07-15

170

Energy resource potential of natural gas hydrates  

Science.gov (United States)

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.

Collett, T.S.

2002-01-01

171

Mechanism of gypsum hydration  

Directory of Open Access Journals (Sweden)

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

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

Pacheco, G.

1991-06-01

172

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-06-01

173

Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization  

Science.gov (United States)

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 the 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 of the original and depressurized/repressurized samples are compared. X-ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/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.

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

2008-07-01

174

Use of Hydration Inhibitors to Improve Bond Durability of Aluminum Adhesive Joints  

Science.gov (United States)

An investigation is conducted of the mechanisms by which nitrilotris methylene phosphonic acid (NTMP) and related compounds are adsorbed onto oxidized aluminum surfaces to inhibit hydration and increase the durability of adhesive bonds formed with inhibitor-treated panels. P - O - Al bonds are identified as the basis of adsorption, and it is found that water initially adsorbed onto the etched aluminum surfaces is displaced by the NTMP. The hydration of the NTMP-treated surfaces occurs in three stages, namely the reverisble physisorption of water, the slow dissolution of NTMP followed by rapid hydration of the freshly exposed Al2O3 to AlOOH and further hydration of the surface to Al(OH)3. Five properties of an ideal inhibitor are identified.

Davis, G. D.; Ahearn, J. S.; Matienzo, L. J.; Venables, J. D.

1985-01-01

175

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)

176

New Results on Hydration in M-Type Asteroids  

Science.gov (United States)

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 feature among them. We discuss the impact of our results on interpretations of M-type asteroid composition.

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

2014-11-01

177

Well log evaluation of natural gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane hydrates appear to be the most common in nature. The amount of methane sequestered in gas hydrates is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the hydrate reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas hydrates also represent a significant drilling and production hazard. A fundamental question linking gas hydrate resource and hazard issues is: What is the volume of gas hydrates and included gas within a given gas hydrate occurrence Most published gas hydrate resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas hydrates are dependent on a number of reservoir parameters, including the areal extent ofthe gas-hydrate occurrence, reservoir thickness, hydrate number, reservoir porosity, and the degree of gas-hydrate saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas hydrate saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-hydrate-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas hydrates.

Collett, T.S.

1992-10-01

178

Well log evaluation of natural gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane hydrates appear to be the most common in nature. The amount of methane sequestered in gas hydrates is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the hydrate reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas hydrates also represent a significant drilling and production hazard. A fundamental question linking gas hydrate resource and hazard issues is: What is the volume of gas hydrates and included gas within a given gas hydrate occurrence? Most published gas hydrate resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas hydrates are dependent on a number of reservoir parameters, including the areal extent ofthe gas-hydrate occurrence, reservoir thickness, hydrate number, reservoir porosity, and the degree of gas-hydrate saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas hydrate saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-hydrate-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas hydrates.

Collett, T.S.

1992-10-01

179

Hydration water in dynamics of a hydrated beta-lactoglobulin  

Science.gov (United States)

Incoherent spin-echo signals of a hydrated ?-lactoglobulin protein were investigated, at 275 and 293 K. The intermediate scattering functions I(Q,t) were divided in two contributions from surface water and protein, respectively. On one hand, the dynamics of the surface water follows a KWW stretched exponential function (the exponent is ~0.5), on the other hand, that of the protein follows a single exponential. The present results are consistent with our previous results of hydrated C-phycocyanin combining elastic and quasielastic neutron scattering and by molecular dynamics simulation.

Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.-C.; Longeville, S.

2007-02-01

180

Spectroscopic Determination of Optimal Hydration Time of Zircon Surface  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Los minerales que son inmersos en solución acuosa, desarrollan una carga eléctrica, producida por la aparición de la disociación anfotérica de los grupos hidroxilo formados en superficie. Esta propiedad es específica para cada mineral y la determinación del tiempo de hidratación es fundamental para [...] realizar posteriores estudios de sorción en la interfase sólido/líquido. En este estudio se determinó el tiempo óptimo de hidratación del circón (ZrSiO4), comparando la técnica clásica por titulación potenciométrica con la técnica de fluorescencia a diferentes tiempos. La técnica de fluorescencia fue desarrollada gracias a las impurezas de tierras raras que son contenidas en cantidades traza en los minerales de circón. El análisis por activación neutrónica mostró que las impurezas contenidas en este lote de circón eran principalmente el Dy3+, Eu3+ y el Er3+. El Dy3+ tiene una buena respuesta fluorescente que se incrementa con las moléculas de agua a medida que este elemento se hidrata. Los resultados mostraron que el método potenciométrico es largo y tedioso, pues se requiere un lote por cada tiempo en estudio y toma alrededor de 2 h el análisis, en tanto que el método espectroscópico requiere de una sola muestra que se analiza puntualmente pasado el tiempo requerido, esto sólo toma 5 min, después del cual se continua con el proceso de hidratación. Ámbos métodos mostraron que la superficie del circón requiere de 16 h para alcanzar el tiempo óptimo de hidratación. Abstract in english When a mineral surface is immersed in an aqueous solution, it develops an 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 reliable 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 (NAA) 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 min from only one batch. Both methods showed that the zircon surface have a 16h optimal hydration time.

Eduardo, Ordóñez-Regil; Genoveva, García-Rosales; Nidia, García-González.

2010-09-01

181

Mineral bioprocessing  

Energy Technology Data Exchange (ETDEWEB)

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.

Torma, A.E.

1993-05-01

182

Hydrate problems in deepwater flowlines  

Energy Technology Data Exchange (ETDEWEB)

In the Gulf of Mexico (GOM), the ambient temperature below about 100 meters water depth (the thermocline), is as low as 44 F. The hydrate formation temperature for natural gas at the reservoir pressures encountered in the deeper waters of the GOM is substantially higher than the 44 F ambient temperature. In fact, below about 1,500 foot water depth, naturally occurring gas hydrates are present as ice-like lenses just below the sea floor. Classic dehydration is not possible. The injection of dew point depressants such as methanol or glycol is possible. Insulation is also a possibility. As an example of one selection process for deriving a workable solution to hydrate prevention/control in deepwater flow lines from subsea completions, this paper examines the approach taken to select the solution to the hydrate formation problems on Enserch`s Mississippi Canyon Block MC 441 Field Development Project. The project involved connecting dual flow lines from each well at two 3-well templates in about 1,525 feet of water to a shallow water production facilities platform located m 380 feet of water. Calculations indicated that the gas temperature in an uninsulated flow line would fall to ambient temperature in less than 1 mile from the wellhead. Considering that the platform was located about 3 and 6 miles from the two subsea well templates, and that free water would occur, hydrates were expected to be formed in the flow lines if nothing was done. Various possible hydrate control/prevention methods, including some of those currently in use in the North Sea, were investigated. The method chosen as the cost effective solution for the MC441 field development is a combination of low Cost open cell insulation around the six flow lines in a casing and methanol injection at the wellhead/manifold.

Wang, X.; Bomba, J.G. [R.J. Brown and Associates, Houston, TX (United States). Division of Kvaerner Earl and Wright

1994-12-31

183

The nanostructure of calcium silicate hydrate  

Science.gov (United States)

The nanostructure of C-S-H, the principle binding phase of hydrated cements in concrete, is examined through classical and spectroscopic methods such as solubility, 29Si MAS NMR, inelastic neutron scattering (INS), and small-angle neutron scattering (SANS). A more comprehensive understanding of the nanostructure is proposed. The central finding of this thesis is that variations in Ca/Si ratio, silicate structure, and Ca-OH content of C-S-H are systematically related to previously undiscovered variations in solubility in the CaO-SiO2-H 2O system at room temperature. These relationships show how C-S-H resembles disordered forms of the calcium silicate hydrate minerals 1.4-nm tobermorite [Ca5Si6O16(OH)2·8H 2O] and jennite [Ca9(Si6O18)(OH) 6·8H2O]. For example, in solids lacking Ca-OH groups, the structure resembles a purely tobermorite-like structure, which, when equilibrated in aqueous solutions saturated in Ca(OH)2, has a Ca/Si ratio of 1.5 and a minimum mean silicate chain length of 2; with increasing Ca-OH contents, the structure becomes increasingly jennite-like while showing higher Ca/Si ratios and higher mean chain lengths at saturation in Ca(OH)2. These relationships appear to reconcile the broad variations in the literature. 29Si NMR on concrete specimens aged 43--96 years show that the mean silicate chain length of C-S-H gel ultimately converges to a value of 5. With supporting evidence from chemical analysis and from high Ca-OH contents measured by INS, it is concluded that C-S-H gel formed in Ca3SiO5 pastes eventually equilibrates to a purely jennite-like structure. A Ca/Si ratio of 1.2 in C-S-H gel marks the composition at which Ca-OH groups are eliminated (or introduced) and below which spontaneous silicate polymerization occurs. Leaching studies on cement pastes show that when C-S-H is decalcified below Ca/Si ˜ 1.2, the induced silicate polymerization occurring in situ leads to macroscopic polymerization shrinkage. Cement pastes blended with high contents of mineral additions may be more susceptible to this mechanism. SANS measurements on leached Ca3SiO5 and cement pastes show dramatic variations in surface area with Ca/Si ratio. These variations are attributed to transformations between low- and high-density morphologies of C-S-H.

Chen, Jeffrey J.

184

Mineral Commodities  

Science.gov (United States)

This exercise introduces mineral commodities (elements). Students consider the elements aluminum, iron, copper, nickel, zinc, uranium, lead, gold, mercury and tin and match them with their definintions in a table. Then they use minable grade (minable weight percent) and normal crustal abundance (crustal weight percent) to calculate the concentration factor for several commodities to determine their economic minability. Students then graph their calculations and explain their trend.

Perkins, Dexter

185

Uranium minerals in Chattanooga shale  

International Nuclear Information System (INIS)

Chattanooga shale samples from DeKalb County, Tennessee, were studied with an electron microprobe. Preliminary results show that uranium in concentrations up to 130 ppM is not dispersed uniformly within the kerogen or inorganic matrix. Distinct uranium minerals, such as uraninite, apatite, and titanium bearing oxides, ranging in size from 3 to 180 ?m, are evident on shale surface exposed by polishing. 10 figures

186

Attraction between hydrated hydrophilic surfaces  

Science.gov (United States)

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 contact angle ?adh depends on surface type and lies in the range 65°

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

2014-08-01

187

Polymorphs and Hydrates of Acyclovir  

OpenAIRE

Acyclovir (ACV) has been commonly used as an antiviral for decades. Although the crystal structure of the commercial form, a 3:2 ACV/water solvate, has been known since 1980s, investigation into the structure of anhydrous ACV has been limited. Here, we report the characterization of four anhydrous forms of ACV and a new hydrate in addition to the known hydrate. Two of the anhydrous forms appear as small needles and are stable to air exposure, whereas the third form is morphologically similar ...

Lutker, Katie M.; Quin?ones, Rosalynn; Xu, Jiadi; Ramamoorthy, Ayyalusamy; Matzger, Adam J.

2011-01-01

188

Gas Hydrate and Pore Pressure  

Science.gov (United States)

Many efforts have been devoted to quantify excess pore pressures related to gas hydrate dissociation in marine sediments below the BSR using several approaches. Dissociation of gas hydrates in proximity of the BSR, in response to a change in the physical environment (i.e., temperature and/or pressure regime), can liberate excess gas incrising the local pore fluid pressure in the sediment, so decreasing the effective normal stress. So, gas hydrate dissociation may lead to excess pore pressure resulting in sediment deformation or failure, such as submarine landslides, sediment slumping, pockmarks and mud volcanoes, soft-sediment deformation and giant hummocks. Moreover, excess pore pressure may be the result of gas hydrate dissociation due to continuous sedimentation, tectonic uplift, sea level fall, heating or inhibitor injection. In order to detect the presence of the overpressure below the BSR, we propose two approachs. The fist approach models the BSR depth versus pore pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas hydrate stability is deeper with respect to the hydrostatic case. This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas hydrate and free gas concentrations and pore pressure, considering the approximation of the Biot theory in case of low frequency, i.e. seismic frequency. Knowing the P and S seismic velocity from seismic data analysis, it is possibile to jointly estimate the gas hydrate and free gas concentrations and the pore pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson ratio. Our modeling suggests that the areas characterized by shallow waters (i.e., areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition. Moreover, the knoweledge of seismic velocities can be considered an powerful tool to detect the overpressure in case that the pore pressure is equal to the hydrostatic pressure plus the 50% of the difference between the lithostatic and the hydrostatic pressure. In conclusions, an accurate analysis of the BSR nature and the pore pressure are required to improve the reliability of the gas-phase estimation for different target, such as gas hydrate and free gas exploitations and environmental studies.

Tinivella, Umberta; Giustiniani, Michela

2014-05-01

189

Effects of Different Mineral Admixtures on the Properties of Fresh Concrete  

OpenAIRE

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 i...

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

2014-01-01

190

Identification of cave minerals by Raman spectroscopy: new technology for non-destructive analysis  

OpenAIRE

The usual tools are X-ray powder diffraction, the optical microscope, and the scanning electron microscope. X-ray diffraction gives a definitive fingerprint by which the mineral can be identified by comparison with a catalog of reference patterns. However, samples must be ground to powder and unstable hydrated minerals may decompose before analysis is complete. Raman spectroscopy also provides a fingerprint useful for mineral identification but with the additional advantage that some a-priori...

White William B.

2006-01-01

191

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

Science.gov (United States)

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.

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

2007-01-01

192

A reaction-diffusion model for the hydration/setting of cement  

CERN Document Server

We propose a heterogeneous reaction-diffusion model for the hydration and setting of cement. The model is based on diffusional ion transport and on cement specific chemical dissolution/precipitation reactions under spatial heterogeneous solid/liquid conditions. We simulate the spatial and temporal evolution of precipitated micro structures starting from initial random configurations of anhydrous cement particles. Though the simulations have been performed for two dimensional systems, we are able to reproduce qualitatively basic features of the cement hydration problem. The proposed model is also applicable to general water/mineral systems.

Tzschichholz, F; Zanni, H

1995-01-01

193

Monitoring genotoxic exposure in uranium miners  

Energy Technology Data Exchange (ETDEWEB)

Recent data from deep uranium mines in Czechoslovakia indicated that in addition to radon daughter products, miners are also exposed to chemical mutagens. Mycotoxins were identified as a possible source of mutagenicity present in the mines. Various methods of biomonitoring were used to examine three groups of miners from different uranium mines. Cytogenetic analysis of peripheral lymphocytes, unscheduled DNA synthesis (UDS) in lymphocytes, and lipid peroxidation (LPO) in both plasma and lymphocytes were studied on 66 exposed miners and 56 controls. Throat swabs were taken from 116 miners and 78 controls. Significantly increased numbers of aberrant cells were found in all groups of miners, as well as decreased UDS values in lymphocytes and increased LPO plasma levels in comparison to controls. Molds were detected in throat swabs from 27% of miners, and 58% of these molds were embryotoxic. Only 5% of the control samples contained molds and none of them was embryotoxic. The following mycotoxins were isolated from miners' throat swab samples: rugulosin, sterigmatocystin, mycophenolic acid, brevianamid A, citreoviridin, citrinin, penicilic acid, and secalonic acid. These data suggest that mycotoxins are a genotoxic factor affecting uranium miners.

Sram, R.J.; Binkova, B.; Dobias, L.; Roessner, P.T.; Topinka, J.; Vesela, D.; Vesely, D.; Stejskalova, J.; Bavorova, H.; Rericha, V. (Institute of Experimental Medicine, Prague (Czechoslovakia))

1993-03-01

194

Hydrogen (H2) Storage in Clathrate Hydrates  

OpenAIRE

Structure, stability and reactivity of clathrate hydrates with or without hydrogen encapsulation are studied using standard density functional calculations. Conceptual density functional theory based reactivity descriptors and the associated electronic structure principles are used to explain the hydrogen storage properties of clathrate hydrates. Different thermodynamic quantities associated with H2-trapping are also computed. The stability of the H2-clathrate hydrate comple...

Chattaraj, Pratim Kumar; Bandaru, Sateesh; Mondal, Sukanta

2010-01-01

195

Kinetics of methane hydrate replacement with carbon dioxide and nitrogen gas mixture using in situ NMR spectroscopy.  

Science.gov (United States)

In this study, the kinetics of methane replacement with carbon dioxide and nitrogen gas in methane gas hydrate prepared in porous silica gel matrices has been studied by in situ (1)H and (13)C NMR spectroscopy. The replacement process was monitored by in situ (1)H NMR spectra, where about 42 mol % of the methane in the hydrate cages was replaced in 65 h. Large amounts of free water were not observed during the replacement process, indicating a spontaneous replacement reaction upon exposing methane hydrate to carbon dioxide and nitrogen gas mixture. From in situ (13)C NMR spectra, we confirmed that the replacement ratio was slightly higher in small cages, but due to the composition of structure I hydrate, the amount of methane evolved from the large cages was larger than that of the small cages. Compositional analysis of vapor and hydrate phases was also carried out after the replacement reaction ceased. Notably, the composition changes in hydrate phases after the replacement reaction would be affected by the difference in the chemical potential between the vapor phase and hydrate surface rather than a pore size effect. These results suggest that the replacement technique provides methane recovery as well as stabilization of the resulting carbon dioxide hydrate phase without melting. PMID:25565018

Cha, Minjun; Shin, Kyuchul; Lee, Huen; Moudrakovski, Igor L; Ripmeester, John A; Seo, Yutaek

2015-02-01

196

Thermal conductivity of tetrahydrofuran hydrate  

OpenAIRE

The thermal conductivity of tetrahydrofuran hydrate has been measured in the temperature region 2 – 220 K by the steady-state potentiometric method. The temperature dependence of the thermal conductivity exhibits behavior typical of amorphous substances. It is shown that above 100 K the mean free path of the phonons is considerably smaller than the lattice parameter and is no longer dependent on temperature.

Krivchikova, A. I.; Manzheliia, V. G.; Korolyuka, O. A.; Gorodilova, B. Ya; Romantsovaa, O. O.

2004-01-01

197

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

198

Electron hydration: questions and controverses  

International Nuclear Information System (INIS)

We try to review the principal questions which have remained unanswered up to now on the dynamics of electron hydration. We also report controversies on the interpretation of the recent femtosecond laser photolysis experiments, and put forward some new hypotheses concerning the formation of the incompletely relaxed electron. 27 refs

199

Global investigation of hydrated exposures on Mars: Evidence for a clay cycle  

Science.gov (United States)

The discovery of hydrated minerals including clays, carbonates and sulfates on Mars has spawned a new era of intense scrutiny of its ancient (> 4 Ga) aqueous environments Over the years, many thorough investigations of selected sites have been carried out, from which local alteration scenarios have been derived, some of strong astrobiological relevance and justifying sending rovers there such as the MSL. By comparison, our approach is to investigate the chemical alteration of Mars on a global scale from a systematic overview of the hydrated signatures detected by the NIR imaging spectrometers CRISM and OMEGA. We present the main results of this global investigation in terms of composition, geological settings and age of the hydrated deposits. Hydrated mineral exposures are predominantly found in Noachian terrains with a homogenous surface density. The northern plains are not devoid of alteration signatures indicating Mars was altered on a planetary scale. Over 80% of the sites exhibit signatures of Fe/Mg smectites/vermiculite with some evidence for inter-stratification. Great mineral diversity is reported: Al-bearing smectites and kaolins, chlorites, opaline silica, zeolites, serpentines, prehnite, micas, carbonates and epidote. Diverse geological settings exist, but the dominant morphological contexts are impact craters which in the majority of cases likely excavated hydrated minerals. On Earth, clays form, are transformed and accumulate in 6 geological contexts: pedogenic, detrital, authigenic, diagenetic, metamorphic and hydrothermal. Detailed mineral/morphological investigations of sites of interest reveal that all these geological contexts are also found on Mars and hint towards the existence of a clay cycle during the Noachian. While these contexts collectively suggest the presence of a clay cycle on early Mars, their spatial and temporal relationship still remains to be established. In particular, the lack of plate tectonics on Mars renders less likely the possibility of multiple cycles. However the clear association between fluvial structures and hydrated minerals for some deposits supports that alteration at the surface could have occurred. In other locations, the degraded contexts, younger resurfacing processes and inherent limitations of orbital remote sensing make it difficult to constrain the alteration and putative clay cycle during the Pre- to Early-Noachian eons.

Carter, J.; Poulet, F.

2012-04-01

200

Handbook of gas hydrate properties and occurrence  

Energy Technology Data Exchange (ETDEWEB)

This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

Kuustraa, V.A.; Hammershaimb, E.C.

1983-12-01

201

The chemical composition of mineral trioxide aggregate.  

Science.gov (United States)

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

Camilleri, Josette

2008-10-01

202

Thermal conductivity of hydrate-bearing sediments  

Science.gov (United States)

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.

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

2009-01-01

203

Formation of LiBH4 hydrate with dihydrogen bonding  

International Nuclear Information System (INIS)

Highlights: ? Lithium borohydride hydrate (LiBH4·H2O) was formed at room temperature. ? The structure of LiBH4·H2O was found to be monoclinic with the space group P21/c. ? H?H contacts would produce dihydrogen bonds in LiBH4·H2O crystal. - Abstract: Lithium borohydride hydrate (LiBH4·H2O) was formed at room temperature when LiBH4 was exposed to air with about 5% relative humidity. The O–H stretching peak and the H–O–H bending peak that originated in a hydration water molecule were observed in an infrared spectrum. The structure of LiBH4·H2O was found to be monoclinic with the space group P21/c from a powder X-ray measurement using the Rietveld analysis and a density functional theory (DFT) calculation. The H?H contacts in the structure calculated by geometry optimization were 1.58–2.02 Å, which were much shorter than twice the value of the van der Waals radius of a hydrogen atom (2.4 Å). These H?H contacts would produce dihydrogen bonds. The MD simulation at 300 K confirmed that the structural model is stable, and the BH4? tetrahedron rotates frequently in a time order of a pico-second at 300 K.

204

Cohort study of mortality of vermiculite miners exposed to tremolite.  

OpenAIRE

A cohort of 406 men employed before 1963 for at least one year in a vermiculite mine in Montana was followed up until July 1983. The vermiculite ore as fed to the mill contained 4-6% of amphibole fibre in the tremolite series. Vital status was established in all but one of the 406 and death certificates were obtained and coded for 163 of the 165 men who died. Compared with white men in the United States, the cohort experienced excess mortality from all causes (SMR 1.17), respiratory cancer (S...

Mcdonald, J. C.; Mcdonald, A. D.; Armstrong, B.; Sebastien, P.

1986-01-01

205

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)

206

Ice formation during gas hydrate decomposition  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-07-01

207

Fire extinction utilizing carbon dioxide hydrate  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

208

Dipolar response of hydrated proteins  

CERN Document Server

The paper presents an analytical theory and numerical simulations of the dipolar response of hydrated proteins. The effective dielectric constant of the solvated protein, representing the average dipole moment induced at the protein by a uniform external field, shows a remarkable variation among the proteins studied by numerical simulations. It changes from 0.5 for ubiquitin to 640 for cytochrome c. The former value implies a negative dipolar susceptibility of ubiquitin, that is a dia-electric dipolar response and negative dielectrophoresis. It means that a protein carrying an average dipole of ~240 D is expected to repel from the region of a stronger electric field. This outcome is the result of a negative cross-correlation between the protein and water dipoles, compensating for the positive variance of the protein dipole in the overall dipolar susceptibility. This phenomenon can be characterized as overscreening of protein's dipole by the hydration shell. In contrast to the neutral ubiquitin, charged protei...

Matyushov, Dmitry V

2011-01-01

209

Early hydration of cementitious systems  

OpenAIRE

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...

Juilland, Patrick

2009-01-01

210

Hydrophobic hydration of amphipathic peptides.  

OpenAIRE

Biomolecular surfaces and interfaces are commonly found with apolar character. The hydrophobic effect thus plays a crucial role in processes involving association with biomolecular surfaces in the cellular environment. By computer simulation, we compared the hydrogen bonding structures and energetics of the proximal hydration shells of the monomer and dimer from a recent study of an extrinsic membrane peptide, melittin. The two peptides were studied in their amphipathic alpha-helical forms, w...

Cheng, Y. K.; Sheu, W. S.; Rossky, P. J.

1999-01-01

211

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)

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.

NONE

1997-12-31

212

Shear dynamics of hydration layers  

Science.gov (United States)

Molecular dynamics (MD) simulations have been performed to investigate the shear dynamics of hydration layers of the thickness of D =0.61-2.44nm confined between two mica surfaces. Emphases are placed on the external shear response and internal relaxation properties of aqueous films. For D =0.92-2.44nm liquid phase, the shear responses are fluidic and similar to those observed in surface force balance experiments [U. Raviv and J. Klein, Science 297, 1540 (2002)]. However, for the bilayer ice (D=0.61nm) [Y. S. Leng and P. T. Cummings, J. Chem. Phys. 124, 74711 (2006)] significant shear enhancement and shear thinning over a wide range of shear rates in MD regime are observed. The rotational relaxation time of water molecules in this bilayer ice is found to be as high as 0.017ms (10-5s). Extrapolating the shear rate to the inverse of this longest relaxation time, we obtain a very high shear viscosity for the bilayer ice, which is also observed quite recently for D ?0.6±0.3nm hydration layers [H. Sakuma et al., Phys. Rev. Lett. 96, 46104 (2006)]. We further investigate the boundary slip of water molecules and hydrated K+ ions and concluded that no-slip boundary condition should hold for aqueous salt solution under extreme confinement between hydrophilic mica surfaces, provided that the confined film is of Newtonian fluid.

Leng, Yongsheng; Cummings, Peter T.

2006-09-01

213

Dielectric response of hydrated proteins  

Science.gov (United States)

We study dipolar susceptibility of hydrated proteins, representing the average dipole moment induced at the hydrated protein by a uniform external field. This parameter shows remarkable variation among proteins. We find a negative value of the dipolar susceptibility for some proteins, which implies a dia-electric dipolar response and negative dielectrophoresis. Such proteins, even though carrying significant permanent dipole moments, repel from the electric field. This outcome is the result of a negative cross-correlation between the protein and water dipoles, compensating for the positive variance of the intrinsic protein dipole in the overall dipolar susceptibility. We therefore suggest that the dipolar response of proteins in solution is strongly affected by the coupling of the protein surface charge to the hydration water. The protein-water dipolar cross-correlations are long-ranged, extending approximately 2 nm from the protein surface into the bulk. A similar correlation length of about 1 nm is found for the electrostatic potential. The model is applied to the analysis of light absorption by protein solutions in the THz window of radiation. Here we also find significant deviations of the absorption coefficient from the predictions of traditional theories.

Matyushov, Dmitry

2013-03-01

214

Compression behaviour of anhydrous and hydrate forms of sodium naproxen.  

Science.gov (United States)

The aim of the present work was to investigate the technological properties and the compression behaviour of the anhydrous and hydrate solid forms of sodium naproxen. Among the hydrates, the following forms were studied: the monohydrate (MSN), obtained by dehydrating a dihydrated form (DSN) in each turn obtained by exposing the anhydrous form at 55% RH; a dihydrated form (CSN) obtained by crystallizing sodium naproxen from water, the tetrahydrated form (TSN) obtained by exposing the anhydrous form at 75% RH. The physico-chemical (crystalline form and water content), the micromeritic (crystal morphology and particle size) and the mechanical properties (Carr's index, apparent particle density, compression behaviour, elastic recovery and strength of compact) were evaluated. We made every effort to reduce differences in crystal habit, particle size and distribution, and amount of absorbed water among the samples, so that the only factors affecting their technological behaviour would be the degree of hydration and the crystalline structure. This study demonstrates a correlation between the compression behaviour and the water molecules present in the crystalline structures. The sites where water molecules are accommodated in the crystalline structure behave like weak points where the crystalline lattice yields under compression. The crystal deformability is proportional to the number of water molecules in these sites; the higher the water content, the higher the deformability, because the densification behaviour changes from a predominantly elastic deformation to a plastic behaviour. The deformability is responsible for a higher densification tendency that favours larger interparticle bonding areas that may explain the better tabletability of TSN and CSN. PMID:20117196

Malaj, Ledjan; Censi, Roberta; Gashi, Zehadin; Di Martino, Piera

2010-05-10

215

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

Directory of Open Access Journals (Sweden)

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.

Kathryn M. Linton

2014-07-01

216

Hydrogen (H2) Storage in Clathrate Hydrates  

CERN Document Server

Structure, stability and reactivity of clathrate hydrates with or without hydrogen encapsulation are studied using standard density functional calculations. Conceptual density functional theory based reactivity descriptors and the associated electronic structure principles are used to explain the hydrogen storage properties of clathrate hydrates. Different thermodynamic quantities associated with H2-trapping are also computed. The stability of the H2-clathrate hydrate complexes increases upon the subsequent addition of hydrogen molecules to the clathrate hydrates. The efficacy of trapping of hydrogen molecules inside the cages of clathrate hydrates depends upon the cavity sizes and shapes of the clathrate hydrates. Computational studies reveal that 512 and 51262 structures are able to accommodate up to two H2 molecules whereas 51268 can accommodate up to six hydrogen molecules.

Chattaraj, Pratim Kumar; Mondal, Sukanta

2010-01-01

217

Development of Alaskan gas hydrate resources  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1991-06-01

218

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)

219

South Africa's mineral industry  

International Nuclear Information System (INIS)

The main aim of the Minerals Bureau in presenting this annual review is to provide an up-to-date reference document on the current state of the mineral industry in South Africa. This includes a brief look at the production, trade, economy, resources and deposits of precious metals and minerals, energy minerals, metallic minerals, and non-metallic minerals. One article discusses the production, trade, export, deposits and economy of uranium

220

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

Science.gov (United States)

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

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

2008-02-01

221

The hydration phenomenon in natural rubber latex gloves and its effect on electronic glove monitors.  

Science.gov (United States)

A physical model is presented to explain the phenomenon of hydration in natural rubber latex (NRL) gloves and to account for the observed decrease in electrical resistance of these gloves when exposed to normal saline solution. Microporosity in the rubber is attributed to failure of all latex particles making up a typical glove to completely coalesce with each other and form a continuous film free of interstitial voids. Native proteins and chemicals used in the manufacturing process are suspected of inhibiting coalescence and causing allergic reactions to some wearers after repeated uses. The effect of hydration on the performance of electronic glove monitors is discussed. Glove monitors that can distinguish between hydration and holes are considered to be the most reliable. PMID:10155140

Williams, R E

1994-01-01

222

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)

223

Multicomponent modelling of Portland cement hydration reactions:  

OpenAIRE

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...

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

2012-01-01

224

Occurrence and physical properties of natural gas hydrate and associated gas hydrate-bearing sediments  

Energy Technology Data Exchange (ETDEWEB)

In 2002, the Mallik 5L-38 production research well was drilled to a depth of 1166 m in the Mackenzie Delta of the northwestern Canadian Arctic. Gas-hydrate dominant layers were found to occur within the methane hydrate stability zone at depths from 890 to 1108 m beneath the permafrost zone, where pore-space hydrates were very small in size. Silts and clays which separated the main gas hydrate layers were free of hydrate or had low concentrations. In general, gas hydrate-bearing sandy strata were 10 cm to a few meters thick with an estimated porosity of 25 to 35 per cent. Hydrate saturations in most hydrate layers were 80 per cent pore saturation or more. The many similarities in appearance and occurrence between Mallik and the Nankai Trough in Japan were noted. Both have well-interconnected and highly saturated pore-space gas-hydrate within sandy sediments. Gas hydrate-bearing sand core samples from Mallik 5L-38 were retrieved for various laboratory analyses and for chemical and physical measurements in Japan. Sand core samples containing gas hydrate were stored in pressure vessels and transported to Japan. The vessels were charged with nitrogen gas to 7 MPa and temperatures were maintained at -30 to - 70 degree C. The core samples containing gas hydrates were subjected to X-ray CT imagery measurements to observe the sedimentary textures and gas-hydrate occurrences inside the cores. Various diagnostic techniques were applied to determine their petrophysical properties, biostratigraphy, geochemistry, microbiology, and gas hydrate characteristics. It was determined that pore-space hydrates contained in sands are composed mostly of structure I hydrates. The influence of temperature on P and S wave velocities of the sands was also evaluated and measurements were taken of mechanical strength, thermal conductivity and electrical resistivity.

Uchida, T.; Waseda, A. [Japan Petroleum Exploration Co. Ltd., Chiba (Japan); Ochiai, K.; Kato, A.; Kono, F. [Japan National Oil Corp., Chiba (Japan); Takeya, S. [National Inst. of Advanced Industrial Science and Technology, Sapporo (Japan); Sasaki, H. [Osaka Gas Co., Osaka (Japan); Sawamura, F. [Japex Geophysical Inst., Tokyo (Japan)

2004-07-01

225

New gas hydrate polymeric growth promoters  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are currently being considered as a method of transporting and storing natural gas. However, the slow formation rates of hydrates mean that hydrate promoters must be used in order to ensure that the use of hydrates is economically feasible. This study tested poly2-acrylamido-2-methylpropane sulfonic acid with sodium salt and poly(acrylic acid) with sodium salt in order to characterize their effects on the kinetics of hydrate formation. The polymers were inserted into a crystallizer with a syringe. The crystallizer was pressurized with pure methane after the temperature of the system had stabilized. Pressure drop was then used to calculate the number moles of gas entering the crystallizer during the growth period. Deionized water was used a reference sample. The experiments were conducted using a methane-water system at pressures ranging from 5800 to 7200 kPa and at a temperature of 277 K. Results of the experiments showed that both polymers increased gas uptake rates of the methane hydrates. Hydrate growth increased with higher pressure driving forces for the poly(2-acrylamido-2-methylpropane sulfonic acid) with sodium salt. Hydrate growth was enhanced at lower molecular weights and higher weight concentrations for the poly(acrylic acid). Growth rate was more aggressive at higher concentrations for both polymers. It was concluded that the polymers can be used to develop gas hydrate storage and transportation technologies. 12 refs., 2 tabs., 11 figs.

Servio, P.; Al-Adel, S. [McGill Univ., Montreal, PQ (Canada). Dept. of Chemical Engineering

2008-07-01

226

Desalination utilizing clathrate hydrates (LDRD final report).  

Energy Technology Data Exchange (ETDEWEB)

Advances are reported in several aspects of clathrate hydrate desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of hydrate guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate hydrate growth, control the morphology of the solid hydrate material formed, and facilitate separation of hydrate solids from concentrated brine. The rate of R141b hydrate formation was determined and found to depend only on the degree of supercooling. The rate of R141b hydrate formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b hydrates from brine. Preliminary experiments using the guest species, difluoromethane, showed that hydrate formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II hydrate. Additionally, the hydrate of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer hydrate. Molecular dynamics simulations show that R141b hydrate is stable at temperatures up to 265K, while the isomer hydrate is only stable up to 150K. Despite hydrogen bonding between guest and host, R141b molecules rotated freely within the water cage. The Raman spectrum of R141b in both the pure and hydrate phases was also compared with vibrational analysis from both computational methods. In particular, the frequency of the C-Cl stretch mode (585 cm{sup -1}) undergoes a shift to higher frequency in the hydrate phase. Raman spectra also indicate that this peak undergoes splitting and intensity variation as the temperature is decreased from 4 C to -4 C.

Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy (Sandia National Laboratories, Albuquerque, NM); Greathouse, Jeffery A. (Sandia National Laboratories, Albuquerque, NM); Majzoub, Eric H. (University of Missouri, Columbia, MO)

2008-01-01

227

Observation of Sintering of Clathrate Hydrates  

Directory of Open Access Journals (Sweden)

Full Text Available 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 molecules. We observed the sintering process of clathrate hydrates to estimate the rate of sintering. Spherical tetrahydrofuran (THF hydrate particles were used in observations of sintering under a microscope equipped with a CCD camera and a time-lapse video recorder. We found that THF hydrate particles stored at temperatures below the equilibrium condition sintered like ice particles. The sintering part was confirmed to be not ice, but THF hydrate, by increasing the temperature above 273 K after each experiment. The sintering rate was lower than that of ice particles under the normal vapor condition at the same temperature. However, it became of the same order when the atmosphere of the sample was saturated with THF vapor. This indicates that the sintering rate of THF hydrate was controlled by the transportation of guest molecules through the vapor phase accompanied with water molecules.

Kazutoshi Gohara

2010-12-01

228

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

Science.gov (United States)

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

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

2014-09-25

229

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.

230

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

Science.gov (United States)

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.

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

2011-12-01

231

Inhalation hazards to uranium miners  

International Nuclear Information System (INIS)

Using both large and small experimental animals, this project is investigating levels of uranium-mine air contaminants that produce respiratory system disease in miners. Lung cancer incidence and deaths from degenerative lung disease are significantly elevated among uranium miners, but the cause-effect relationships for these diseases are based on inadequate epidemiological data. This project identifies agents or combinations of agents (both chemical and radiological), and their exposure levels, that produce respiratory tract lesions, including respiratory epithelial carcinoma, pneumoconiosis, and emphysema. Histopathological data for 100-working-level (WL) exposure rates show a significant increase in lung tumor risk over 1000-WL exposure rates for comparable cumulative radon-daughter exposures. Exposure of rats to radon daughters and other contaminants continues; the exposure of beagle dogs to uranium ore dust alone was terminated. Renal function and hematology data on ore-dust-exposed dogs are reported. 1 figure, 5 tables

232

Analysis of mixed-layer clay mineral structures  

Science.gov (United States)

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.

Bradley, W.F.

1953-01-01

233

Formation rate of natural gas hydrate  

Energy Technology Data Exchange (ETDEWEB)

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

Mork, Marit

2002-07-01

234

Hydration in soccer: a review  

Directory of Open Access Journals (Sweden)

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.

Monteiro Cristiano Ralo

2003-01-01

235

Hydration in soccer: a review  

Scientific Electronic Library Online (English)

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.

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

2003-08-01

236

Hydration dynamics of aqueous nitrate  

OpenAIRE

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 asymmet...

Thøgersen, Jan; Re?hault, Julien; Odelius, Michael; Ogden, Tom; Jena, Naresh K.; Jensen, Svend J. Knak; Keiding, Søren R.; Helbing, Jan

2013-01-01

237

Clay Minerals and Health  

OpenAIRE

The aim of this study is to examine clay minerals, which take very importantplace in relationships of minerals and human health. They have high areadensity, adsorption capacity, rheological properties, chemical inertia and verylow or nontoxic effects to human health. So, they are widely used in medicaltreatments. Commercially used clay minerals are; smectit, polygrstite, caoliniteand talc. The other clay minerals are under investigations for medicaltreatments.

Abdurrahman Dalg?ç; Orhan Kavak

2004-01-01

238

Cement minerals at elevated temperature: Thermodynamic and structural characteristics  

International Nuclear Information System (INIS)

Large quantities of cementitious materials may be used in the construction of a potential nuclear waste repository. Temperatures in the emplacement drifts may reach over 200 C owing to decay heat from radioactive waste for various ''extended-dry'' repository scenarios. Despite its potential significance, the mineralogic response of cement to elevated temperature is not well known. The chemistry of fluid introduced to the repository from cementitious materials can also have a significant impact on repository performance. The masses of water associated with the use of cementitious materials such as shotcrete, which includes both structural and pore water, can be sizable. Pore water may be driven out by heating, and structural water may be released through phase dehydration. An experimental and modeling program has been designed to elucidate the structural and thermodynamic response of cement minerals to elevated temperature. The components of the program include: (a) synthesis of hydrated Ca-silicates; (b) structural analysis of cement phases during 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

239

Spectrophotometric Determination of Thorium in Low Grade Minerals and Ores  

International Nuclear Information System (INIS)

The following method is intended for the determination of microgram quantities of thorium in samples of minerals and ores. The mineral sample is decomposed by repeated sintering with sodium peroxide. After digestion with water thorium peroxide hydrate is recovered by centrifugation and dissolved in hydrochloric acid. Thorium is determined spectrophotometrically with naphtarson after its separation from metals forming chloro complexes which are adsorbed on a strongly basic anion exchange resin. Interferences from a few different ions have been studied. The time required for the analysis of one sample is about 4 hours, when analysing 12 samples simultaneously

240

Sorption Energy Maps of Clay Mineral Surfaces  

Energy Technology Data Exchange (ETDEWEB)

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.

Cygan, Randall T.; Kirkpatrick, R. James

1999-07-19

241

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

242

Hydrate Kinetics Study and Exhibition Display Preparation  

OpenAIRE

The article conducted survey of the literature, concerning hydrate formation. The author took part in empirical data acquisition, processing and analysis at the exhibition display of Institute of the Earth Cryosphere of Siberian Branch of Russian Academy of Sciences, worked out and launched experimental assembly for propane hydrate formation kinetics study at Tyumen State University laboratory?

Ermolaev, Alexey S.

2011-01-01

243

Overview of gas hydrates in submarine slopes  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are solid crystalline compounds consisting of hydrogen-bonded water molecules that form a rigid crystal lattice stabilized by encaged gas molecules. Their stability is confined to low-temperature, high-pressure regimes such as those found in permafrost regions and under the seafloor on continental slopes. In-situ natural gas hydrate deposits are typically located in marine sediments at temperatures of 5 to 10 degrees C. The critical factors influencing hydrate formation and stability are pressure, temperature, gas composition, volume of bulk free water, salinity, gas availability, sediment type, and the presence of catalysts or inhibitors. Circumstantial evidence suggests that large submarine landslides along the continental margins can be triggered by the weakening of hydrate bearing sediments. Hydrate dissociation results in loss of solid material, production of free gas, and increased fluid pressures, all which have the effect of reducing sediment strength. These underwater landslides have the potential to destroy offshore equipment, jeopardize safety of personnel, and generate tsunamis. This paper presented recent results and advances on the intersection of gas hydrates and submarine slope stability, with particular reference to the role of gas hydrates in triggering or propagating submarine mass movements. It was concluded that the cause of slope failures is not fully understood because of the complexities of gas hydrates and their interactions with the host sediment, combined with the high cost of laboratory and field investigations. 35 refs., 2 figs.

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

2009-07-01

244

Evaluation of hydration indexes in kale leaves  

Directory of Open Access Journals (Sweden)

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.

Adonai G. Calbo

2011-01-01

245

Evaluation of hydration indexes in kale leaves  

Scientific Electronic Library Online (English)

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.

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

246

Hydrate Kinetics Study and Exhibition Display Preparation  

Directory of Open Access Journals (Sweden)

Full Text Available The article conducted survey of the literature, concerning hydrate formation. The author took part in empirical data acquisition, processing and analysis at the exhibition display of Institute of the Earth Cryosphere of Siberian Branch of Russian Academy of Sciences, worked out and launched experimental assembly for propane hydrate formation kinetics study at Tyumen State University laboratory?

Alexey S. Ermolaev

2011-10-01

247

Physical property changes in hydrate-bearing sediment samples due to depressurization/repressurization  

Science.gov (United States)

Physical property measurements on cores containing natural gas hydrate are typically performed on material exposed to non-in situ conditions at least briefly during recovery. In situ temperature and effective stress are difficult to maintain during core recovery, but pressure-coring systems such as the HYACINTH, Fugro, and IODP PCS can maintain in situ hydrostatic pressure during core retrieval. To simulate effects of transferring pressure-core samples to storage vessels, the USGS conducted physical property measurements on Ottawa sand samples containing methane gas and gas hydrate before and after samples were depressurized out of, then repressurized back into, the gas hydrate stability field. For measurements made along a sample's cylindrical axis, compressional and shear wave speed, shear strength, and thermal conductivity increased 10 to 30 percent following a 5 minute excursion from the gas hydrate stability field. Experiments were conducted in unsaturated sand in the presence of methane gas, and increases in measured physical property values resulting from the repressurization cycle can be attributed to a redistribution of water and gas hydrate within the sample. Redistribution of water and re-formation of gas hydrate is inferred from X- Ray Computed Tomography of a cylindrical hydrate-bearing Ottawa sand sample similar to the USGS samples. During the excursion from the gas hydrate stability field, images collected at the Lawrence Berkeley National Laboratory demonstrate gas hydrate dissociates first at the outer surface, where heat is efficiently transferred from a temperature-controlled bath. Upon repressurizing to stable conditions, gas hydrate remaining near the sample's central axis draws water away from the outer part of the sediment sample, and new gas hydrate grows most rapidly close along the central axis, where the original gas hydrate never dissociated during depressurization. These results can be compared to those obtained by Georgia Tech on water-saturated, natural sediment cores collected in the Gulf of Mexico. Pressure cores that never experienced a depressurization cycle and were analyzed in the Georgia Tech Instrumented Pressure Testing Chamber (IPTC) yielded significantly higher seismic velocities than conventional cores recovered at the same depth and tested at atmospheric pressure. This effect was observed even though the cores did not contain gas hydrate, attesting to the importance of maintaining pressure if the goal is to constrain in situ physical properties. A second set of measurements at Georgia Tech focused on natural samples with pore space 100 percent saturated with synthetic hydrate at low confining pressures. These samples also produced seismic velocities closer to those obtained from borehole logs, but this effect is sediment-dependent, and therefore difficult to correlate with in situ properties. Though laboratory facilities continue to provide insight via controlled studies of model systems, confidently characterizing in situ mechanical and thermal properties of hydrate-bearing material will require emphasis not on repressurized samples, but on cores that have never experienced a depressurization cycle. The consequences of releasing effective stress during pressure coring is unknown, and currently under investigation.

Waite, W. F.; Kneafsey, T. J.; Santamarina, J. C.; Winters, W. J.; Yun, T.; Mason, D. H.; Ruppel, C. D.

2006-12-01

248

Nuclear minerals in Pakistan  

International Nuclear Information System (INIS)

Strategic importance of Nuclear Minerals was recognized during early formative years of the Pakistan Atomic Energy Commission, and prospecting for uranium was started in Dera Ghazi Khan in collaboration with the Geological Survey of Pakistan (GSP) as early as 1961. Later, the responsibility for countrywide surveys and exploration was fully entrusted with PAEC and in this respect a Directorate of Nuclear Minerals(DNM) was established in 1966 at Lahore. Later, DNM was shifted to the Atomic Energy Centre (AEC), Lahore building and renamed as Atomic Energy Minerals Centre. It has state-of-the-art Chemistry, Mineralogy, Remote Sensing and Electronics Laboratories and an Ore Processing Pilot Plant. The Centre has Prospecting, Exploration, Geophysics, Geochemistry, Geo-tectonics, Mining and Drilling Sections. Regional Offices have been established to facilitate work at Karachi, Quetta and Peshawar. Siwaliks were recognized as a favorable geological formation of prime importance. Sandstone-shale sequence of Siwaliks Formation is exposed in all provinces of Pakistan and in Azad Jammu and Kashmir (AJK), broadly categorized into Rajanpur-Dera Ghazi Khan, Bannu Basin-Kohat Plateau and Potwar-AJK zones. Baghalchur, Nangar Nai and Taunsa uranium deposits have been discovered in the Rajanpur- D.G. Khan Zone. Qabul Khel and Shanawah Uranium deposits have been discovered in the Shanawah-Kohat Plateau Zone. Prospection and exploration is in progress. The first uranium mine was opened agress. The first uranium mine was opened at Baghalchur, and uranium mill was established at D.G Khan in 1977-78 all by indigenous effort. The uranium mine was the most advanced and mechanized mine of that time in the country. Later, a second uranium mine was opened at Qabul Khel in 1992, which was based on a new and advanced in situ leach technology, developed to suit local geological and ore zone parameters. Mining of Nanganai and Taunsa Deposits was started respectively in 1996 and 2002, and is also based on in situ leach technology which is low cost and environment friendly. (author)

249

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

250

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2005-02-01

251

Variation of corneal refractive index with hydration  

International Nuclear Information System (INIS)

We report the effect of changes in the corneal hydration on the refractive index of the cornea. Using optical coherence tomography (OCT), the geometrical thickness and the group refractive index of the bovine cornea were derived simultaneously as the corneal hydration was varied. The corneal hydration was then calculated from the corneal thickness. The group refractive index of the cornea increased non-linearly as the cornea dehydrated. In addition, a simple mathematical model was developed, based on the assumption that changes in corneal hydration occur only in the interfibrilar space with constant water content within the collagen fibrils. Good agreement between the experimental results and the mathematical model supports the assumption. The results also demonstrate that the measurement of refractive index is a quantitative indicator of corneal hydration

252

Variation of corneal refractive index with hydration  

Energy Technology Data Exchange (ETDEWEB)

We report the effect of changes in the corneal hydration on the refractive index of the cornea. Using optical coherence tomography (OCT), the geometrical thickness and the group refractive index of the bovine cornea were derived simultaneously as the corneal hydration was varied. The corneal hydration was then calculated from the corneal thickness. The group refractive index of the cornea increased non-linearly as the cornea dehydrated. In addition, a simple mathematical model was developed, based on the assumption that changes in corneal hydration occur only in the interfibrilar space with constant water content within the collagen fibrils. Good agreement between the experimental results and the mathematical model supports the assumption. The results also demonstrate that the measurement of refractive index is a quantitative indicator of corneal hydration.

Kim, Young L; Walsh, Joseph T Jr.; Goldstick, Thomas K; Glucksberg, Matthew R [Biomedical Engineering Department, Northwestern University, Evanston, IL 60208 (United States)

2004-03-07

253

Study of decomposition thermodynamics of gas hydrate  

Energy Technology Data Exchange (ETDEWEB)

The decomposition thermodynamic conditions of structure II gas hydrate in five reaction systems were studied using visible experimental installations. By means of the Clausius-Clapeyron equation, the numerical analysis theory, the Fourier's Law and the heat-transport equation, a model for calculating decomposition heat of gas hydrate was proposed. The relations between the needed heat quantity, the temperature gradient of heat-transfer medium and the time of hydrate decomposition were determined. Combined with the practice of Fushun mine field, the calculated decompositon heat and time are 600 kJ and 117 h, respectively, with temperature gradient of 3.5 K/m and gas quantity of 14.64 m{sup 3}/t. The results show that the needed heat quantity of hydrate decomposition is large and the time is long. It's possible to prevent coal and gas outburst using gas hydration. 10 refs., 3 figs., 1 tab.

Wu Qiang; Zhang Bao-yong; Wang Yong-jing [Heilongjiang Institute of Science & Technology, Harbin (China). Department of Safety Engineering & Technology

2006-07-01

254

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

255

Hydration of nonelectrolytes in binary aqueous solutions  

Science.gov (United States)

Literature data on the thermodynamic properties of binary aqueous solutions of nonelectrolytes that show negative deviations from Raoult's law due largely to the contribution of the hydration of the solute are briefly surveyed. Attention is focused on simulating the thermodynamic properties of solutions using equations of the cluster model. It is shown that the model is based on the assumption that there exists a distribution of stoichiometric hydrates over hydration numbers. In terms of the theory of ideal associated solutions, the equations for activity coefficients, osmotic coefficients, vapor pressure, and excess thermodynamic functions (volume, Gibbs energy, enthalpy, entropy) are obtained in analytical form. Basic parameters in the equations are the hydration numbers of the nonelectrolyte (the mathematical expectation of the distribution of hydrates) and the dispersions of the distribution. It is concluded that the model equations adequately describe the thermodynamic properties of a wide range of nonelectrolytes partly or completely soluble in water.

Rudakov, A. M.; Sergievskii, V. V.

2010-10-01

256

Methane hydrates in the Chilean continental margin  

Scientific Electronic Library Online (English)

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.

Esteban, Morales G..

2003-08-15

257

Estimation of the degree of hydration of blended cement pastes by a scanning electron microscope point-counting procedure  

International Nuclear Information System (INIS)

A scanning electron microscope (SEM) point-counting technique was employed to study the hydration of plain portland and blended cement pastes containing fly ash or slag. For plain portland cement pastes, the results for the degree of cement hydration obtained by the SEM point-counting technique were consistent with the results from the traditional loss-on-ignition (LOI) of nonevaporable water-content measurements; agreement was within ±10%. The standard deviation in the determination of the degree of cement hydration via point counting ranged from ±1.5% to ±1.8% (one operator, one sample). For the blended cement pastes, it is the first time that the degree of hydration of cement in blended systems has been studied directly. The standard deviation for the degree of hydration of cement in the blended cement pastes ranged from ±1.4% to ±2.2%. Additionally, the degrees of reaction of the mineral admixtures (MAs) were also measured. The standard deviation for the degree of fly ash reaction was ±4.6% to ±5.0% and ±3.6% to ±4.3% for slag. All of the analyses suggest that the SEM point-counting technique can be a reliable and effective analysis tool for use in studies of the hydration of blended cement pastes

258

Hydration Dynamics of Aqueous Nitrate  

DEFF Research Database (Denmark)

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.

ThØgersen, Jan; Réhault, Julien

2013-01-01

259

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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

Thomas E. Williams; Keith Millheim; Bill Liddell

2005-03-01

260

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Thomas E. Williams; Keith Millheim; Buddy King

2004-06-01

261

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Thomas E. Williams; Keith Millheim; Buddy King

2004-07-01

262

Minerals Policy Statement 1: planning and minerals  

Energy Technology Data Exchange (ETDEWEB)

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.

NONE

2006-11-15

263

Radiological hazards to uranium miners  

International Nuclear Information System (INIS)

The purpose of the present document is to review and assess the occupational hazards to uranium miners in Canada. Amendments to regulations set the maximum permissible dose to uranium miners at 50 mSv per year. Uranium miners are exposed to radon and thoron progeny, external gamma radiation and long-lived alpha-emitting radionuclides in dust. The best estimate for the lifetime risk of inhaled radon progeny is about 3 x 10-4 lung cancers per WLM for the average miner, with a range of uncertainty from about 1 -6 x 10-4 per WLM. This central value is nearly twice as high as that recommended by the ICRP in 1981. The probability of serious biological consequences following exposure to external gamma rays is currently under review but is expected to be in the range of 3 - 6 x 10-2 Sv-1. Dosimetric calculations indicate that the stochastic risks per WLM of thoron progeny are about one-third of those for radon progeny. The annual limits on intake of inhaled ore dusts recommended by the ICRP are probably too low by at least a factor of two for the type of ore and dust normally encountered in underground uranium mines in Ontario; this is due in part to the fact that the average diameter of these dusts is five times greater than the value used by the ICRP. Radiological exposures of uranium miners in Canada were reviewed. The biological impact of these exposures were compared with those of conventional accidents on the basis of the years of normal life expectancy that are lost or seriously impaired due to occupational hazards. The objectives in considering all occupational risks are to reduce the total risk from all causes and to use funds spent for health protection as effectively as possible

264

Universal ripper miner  

Science.gov (United States)

A universal ripper miner used to cut, collect and transfer material from an underground mine working face includes a cutter head that is vertically movable in an arcuate cutting cycle by means of drive members, such as hydraulically actuated pistons. The cutter head may support a circular cutter bit having a circular cutting edge that may be indexed to incrementally expose a fresh cutting edge. An automatic indexing system is disclosed wherein indexing occurs by means of a worm gear and indexing lever mechanism. The invention also contemplates a bi-directional bit holder enabling cutting to occur in both the upstroke and the downstroke cutting cycle. Another feature of the invention discloses multiple bits arranged in an in-line, radially staggered pattern, or a side-by-side pattern to increase the mining capacity in each cutting cycle. An on-board resharpening system is also disclosed for resharpening the cutting edge at the end of cutting stroke position. The aforementioned improvement features may be used either singly, or in any proposed combination with each other.

Morrell, Roger J. (Bloomington, MN); Larson, David A. (Minneapolis, MN)

1991-01-01

265

Methane Recovery from Hydrate-bearing Sediments  

Energy Technology Data Exchange (ETDEWEB)

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.

J. Carlos Santamarina; Costas Tsouris

2011-04-30

266

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)

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)

Gaboreau, St

2005-07-01

267

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

Science.gov (United States)

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.

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

2010-06-01

268

Detection and Production of Methane Hydrate  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2011-12-31

269

Mineral Spectroscopy Server  

Science.gov (United States)

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.

Rossman, George

270

Global hydration kinetics of tricalcium silicate cement  

Science.gov (United States)

We reconsider a number of measurements for the overall hydration kinetics of tricalcium silicate pastes having an initial water to cement weight ratio close to 0.5. We find that the time dependent ratio of hydrated and unhydrated silica mole numbers can be well characterized by two power laws in time, x/(1-x)~(t/t×)?. For early times tt× a parabolic behavior (?=1/2). The crossover time is estimated as t×~16 h. We interpret these results in terms of a global second-order rate equation indicating that (a) hydrates catalyze the hydration process for tt×, and (c) the value of the associated rate constant is of magnitude 6×10-7-7×10-6 l mol-1 s-1. We argue, by considering that the hydration process actually occurs via diffusion limited precipitation, that the exponents ?=5/2 and ?=1/2 directly indicate a preferentially platelike hydrate microstructure. This is essentially in agreement with experimental observations of cellular hydrate microstructures for this class of materials.

Tzschichholz, F.; Zanni, H.

2001-07-01

271

Gas Hydrates Research Programs: An International Review  

Energy Technology Data Exchange (ETDEWEB)

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.

Jorge Gabitto; Maria Barrufet

2009-12-09

272

Cancer of the lung in uranium miners  

International Nuclear Information System (INIS)

Cancer of the lung in uranium miners is due to cigarette smoking and high radon daughter product exposure in uranium mines. The incidence of oat cell cancer was very high (75 to 80%) when the miners were exposed to high levels of radiation (WLM). Exposure to these two carcinogens causes squamous cell metaplasia which is also due to upper respiratory inflammatory disease. The squamous metaplasia is not distinguishable as to cause, but when due to carcinogen, these cells persist over a longer period of time and become progressively more and more atypical until invasive neoplasia develops. This is the latent period and lasts about 10 to 15 years

273

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Thomas E. Williams; Keith Millheim; Buddy King

2004-03-01

274

Methane hydrate stability and anthropogenic climate change  

Directory of Open Access Journals (Sweden)

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.

D. Archer

2007-04-01

275

Methane hydrate stability and anthropogenic climate change  

Directory of Open Access Journals (Sweden)

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

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

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

D. Archer

2007-07-01

276

Musculoskeletal performance and hydration status.  

Science.gov (United States)

Maximal performance during competition is the drive many competitors use to train harder. However, there are several variables that contribute to impair a competitor's performance. These variables work by altering the homeostatic mechanisms within the body. Once homeostasis is altered the competitor's body is no longer optimized to face the stresses of the athletic competition. The environment works as an all encompassing variable that will affect sweat rate. During increased environmental heat strain, one must adjust for critical variables, such as temperature regulation, hydration status, and electrolyte levels, as they can contribute to impaired performance. Acclimatization through training and competition will reduce or slow down the effects of these stress factors. Ever evolving recommendations are produced to aid competitors in maintaining homeostasis. Despite all the generic recommendations that are made, however, every athlete needs to individualize their training and competition regimens to optimize personal performance. PMID:19468886

Rothenberg, Joseph A; Panagos, André

2008-06-01

277

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

278

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

Energy Technology Data Exchange (ETDEWEB)

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.

Poole, T.S.; Wakeley, L.D.; Young, C.L. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States). Structures Lab.

1994-03-01

279

SOME STRUCTURAL STUDIES OF CLATHRATE HYDRATES  

OpenAIRE

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...

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

1987-01-01

280

Dynamics of hydration water in protein  

International Nuclear Information System (INIS)

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

281

Clathrate hydrates in cometary nuclei and porosity  

Science.gov (United States)

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.

Smoluchowski, R.

1988-01-01

282

A positron annihilation study of hydrated DNA  

DEFF Research Database (Denmark)

Positron annihilation measurements are reported for hydrated DNA as a function of water content and as a function of temperature (20 to -180.degree. C) for samples containing 10 and 50% wt of water. The ortho-positronium mean lifetime and its intensity show distinct variations with the degree of hydration and with temperature for the 50% sample. The 10% water sample was relatively insensitive to temperature variation. The results indicate that hydrated DNA containing up to 10% water behaves as a rigid crystalline solid but that the rigidity markedly decreases with a further increase in water content until, for approximately 50% water, its properties resemble more those of a highly viscous fluid.

Warman, J. M.; Eldrup, Morten Mostgaard

1986-01-01

283

Uranium mineralization in the sandstones of Dharamsala, Tileli area, Mandi district, Himachal Pradesh, India  

International Nuclear Information System (INIS)

We report here the discovery of sandstone-hosted uranium mineralization in the basal part of upper Dharamsala Formation in Mandi district, Himachal Pradesh. Stratigraphically, the Tertiary sedimentary rocks of Dharamsala Group (Upper Eocene to Lower Miocene; 1400 to 1900 m thick in Tileli area and locally up to 3950 m thick) are bounded by the Main Boundary Thrust (MBT) on the north-east and Palampur Thrust on the south-west, with several other criss-cross thrusts. The beds dip 30 deg - 55 deg north-east. Uranium mineralization was noted at Tileli (eU3O8, 0.086%), and was explored by shielded probe logging of rocks exposed in five trenches. The trench face samples assayed 0.01-0.27% eU3O8, and 0.011-0.076% U3O8 (beta/gamma) with negligible ThO2. The radioactive zone is 540 m long and 5-10 m thick. Radioactivity is due to uraninite and uranophane disseminated in radioactive pockets which are enclosed in hydrated iron oxide, at places admixed with clay. In addition to Tileli, other significant uranium manifestations are Rohin Khad (50m x 10-15m; eU3O8, 0.069%), Garlwar (70m x 5-8m; eU3O8, 0.063%), Chah Ka Dora (80m x 10-15m; eU3O8, 0.036%), Kalthar (50m x 5-8m), Mangwana (5m x 2m; eU3O8, 0.88%) and Manjkhetar (eU3O8 values from grab samples). This study opens up a new environment in Dhais study opens up a new environment in Dharamsala basin to locate possible new uranium prospects. (author)

284

Modeling Natural Gas Productivity Recovery from a Hydrate Reservoir Well  

Directory of Open Access Journals (Sweden)

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.

Bin Dou

2013-04-01

285

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

286

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

OpenAIRE

Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs). The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parame...

Beatrice Castellani; Elena Morini; Mirko Filipponi; Andrea Nicolini; Massimo Palombo; Franco Cotana; Federico Rossi

2014-01-01

287

2. Nonmetallic minerals  

International Nuclear Information System (INIS)

Nonmetallic minerals present various rocks and minerals serve the purpose of obtaining nonmetallic elements and compounds. In this article of book author describes phosphorites, apatite, sulphur, fluorite, diamond, corundum, barite and etc.

288

Establishment of new equipment for testing low dosage hydrate inhibitors  

OpenAIRE

Gas hydrate formation posses a notorious concern for the oil and gas industry, and it only gets bigger because of that the never-ending pursuit of oil and gas compels the industry into deeper and colder waters. Here gas hydrate can from and agglomerate into plugs, jeopardizing pipelines and process equipments. Therefore a variety of methods have been developed to inhibit gas hydrate formation, one of them being to utilize low dosage hydrate inhibitors, which consists of kinetic hydrate inhibi...

Dirdal, Erik Gisle

2013-01-01

289

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)

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)

Ferrage, E

2004-10-15

290

Mineral Commodity Summaries 2012  

Science.gov (United States)

Each chapter of the 2012 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry structure, Government programs, tariffs, 5-year salient statistics, and world production and resources. The MCS is the earliest comprehensive source of 2011 mineral production data for the world. More than 90 individual minerals and materials are covered by 2-page synopses.

2012-01-01

291

Clay Minerals and Health  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study is to examine clay minerals, which take very importantplace in relationships of minerals and human health. They have high areadensity, adsorption capacity, rheological properties, chemical inertia and verylow or nontoxic effects to human health. So, they are widely used in medicaltreatments. Commercially used clay minerals are; smectit, polygrstite, caoliniteand talc. The other clay minerals are under investigations for medicaltreatments.

Abdurrahman Dalg?ç

2004-01-01

292

UK activists expose Canada'  

SCPinfonet

...Environment Minister Peter Kent gets an unexpected welcome in London UK activists expose Canada's tarred reputation Climate & Capitalism An ecosocialist journal Home ... Bizarrely, it was sponsored by Shell and featured as keynote speaker Peter Kent, Canada’s Minister of the Environment and well-known oil industry stooge.... Chivers tells the story: As Kent approached the podium, I leapt from my seat, strode onto the stage and stepped in ... Peter Kent claims to be here to talk about solving climate change, but actually he’s a member of a dangerous anti-environment group ...

293

Minerals planning policy Wales  

Energy Technology Data Exchange (ETDEWEB)

This document sets out the land use planning policy guidance of the National Assembly for Wales in relation to mineral extraction and related development in Wales. It includes all mineral and substances (except marine aggregates) in, on or under land extracted either by underground or surface working. It also lists the parts of the Minerals Planning Guidance that are cancelled.

NONE

2000-12-01

294

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

295

HYDRATION AND ACETYLATION OF LIMONENE: SUPPORTED HETEROPOLYACIDS  

Scientific Electronic Library Online (English)

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

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

1449-14-01

296

Vibrational dynamics of hydration water in amylose  

CERN Document Server

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

Cavatorta, F; Albanese, G; Angelini, N

2002-01-01

297

HYDRATION AND ACETYLATION OF LIMONENE: SUPPORTED HETEROPOLYACIDS  

Directory of Open Access Journals (Sweden)

Full Text Available 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

MARIA CECILIA AVILA

2008-03-01

298

Hydrate Control for Gas Storage Operations  

Energy Technology Data Exchange (ETDEWEB)

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.

Jeffrey Savidge

2008-10-31

299

Separation of water through gas hydrate formation  

DEFF Research Database (Denmark)

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

Boch Andersen, Torben; Thomsen, Kaj

2009-01-01

300

Towards Commercial Gas Production from Hydrate Deposits  

Directory of Open Access Journals (Sweden)

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.

Richard Dawe

2011-01-01

301

ConocoPhillips Gas Hydrate Production Test  

Energy Technology Data Exchange (ETDEWEB)

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

Schoderbek, David; Farrell, Helen; Howard, James; Raterman, Kevin; Silpngarmlert, Suntichai; Martin, Kenneth; Smith, Bruce; Klein, Perry

2013-06-30

302

Bonding by Hydroxide-Catalyzed Hydration and Dehydration  

Science.gov (United States)

A simple, inexpensive method for bonding solid objects exploits hydroxide-catalyzed hydration and dehydration to form silicate-like networks in thin surface and interfacial layers between the objects. The method can be practiced at room temperature or over a wide range of temperatures. The method was developed especially to enable the formation of precise, reliable bonds between precise optical components. The bonds thus formed exhibit the precision and transparency of bonds formed by the conventional optical-contact method and the strength and reliability of high-temperature frit bonds. The method also lends itself to numerous non-optical applications in which there are requirements for precise bonds and/or requirements for bonds, whether precise or imprecise, that can reliably withstand severe environmental conditions. Categories of such non-optical applications include forming composite materials, coating substrates, forming laminate structures, and preparing objects of defined geometry and composition. The method is applicable to materials that either (1) can form silicate-like networks in the sense that they have silicate-like molecular structures that are extensible into silicate-like networks or (2) can be chemically linked to silicate-like networks by means of hydroxide-catalyzed hydration and dehydration. When hydrated, a material of either type features surface hydroxyl (-OH) groups. In this method, a silicate-like network that bonds two substrates can be formed either by a bonding material alone or by the bonding material together with material from either or both of the substrates. Typically, an aqueous hydroxide bonding solution is dispensed and allowed to flow between the mating surfaces by capillary action. If the surface figures of the substrates do not match precisely, bonding could be improved by including a filling material in the bonding solution. Preferably, the filling material should include at least one ingredient that can be hydrated to have exposed hydroxyl groups and that can be chemically linked, by hydroxide catalysis, to a silicate-like network. The silicate-like network could be generated in situ from the filling material and/or substrate material, or could be originally present in the bonding material.

Gwo, Dz-Hung

2008-01-01

303

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-02-01

304

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Steve Runyon; Mike Globe; Kent Newsham; Robert Kleinberg; Doug Griffin

2005-02-01

305

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Thomas E. Williams; Keith Millheim; Bill Liddell

2005-02-01

306

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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.

Thomas E. Williams; Keith Millheim; Bill Liddell

2004-11-01

307

Method of purifying uranium tetrafluoride hydrate and preparing uranium (vi) peroxide hydrate using a fluoride complexing agent  

International Nuclear Information System (INIS)

A method of preparing uranium (VI) peroxide hydrate from uranium tetrafluoride hydrate, comprising the steps of digesting uranium tetrafluoride hydrate in an aqueous acid in the presence of a fluoride complexing agent to produce an aqueous uranium solution, adjusting the aqueous uranium solution to a ph between about 1 to about 3, filtering the aqueous uranium solution to remove undissolved material, reacting the aqueous uranium solution with peroxide to precipitate uranium (VI) peroxide hydrate, and separating the precipitated uranium (VI) peroxide hydrate

308

Raman spectral investigation of thorium bromate hydrate  

International Nuclear Information System (INIS)

Bromates are one of the important groups of oxyhalogen salts. The technological applications of materials based on oxyhalogen salts of bromates are limited as compared to other inorganic compounds. However, several studies on hydrated bromates are reported in the literature due to its magnetic and optical properties. Raman spectroscopic investigations of majority of these crystals are reported in the literature. In the present work we are reporting Raman structural studies of hydrated thorium bromate for the first time

309

CO2 capture by gas hydrate crystallization  

OpenAIRE

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...

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

2009-01-01

310

Hydration Dynamics of Hyaluronan and Dextran  

OpenAIRE

Hyaluronan is a polysaccharide, which is ubiquitous in vertebrates and has been reported to be strongly hydrated in a biological environment. We study the hydration of hyaluronan in solution using the rotational dynamics of water as a probe. We measure these dynamics with polarization-resolved femtosecond-infrared and terahertz time-domain spectroscopies. Both experiments reveal that a subensemble of water molecules is slowed down in aqueous solutions of hyaluronan amounting to ?15 water m...

Hunger, Johannes; Bernecker, Anja; Bakker, Huib j; Bonn, Mischa; Richter, Ralf p

2012-01-01

311

Towards Commercial Gas Production from Hydrate Deposits  

OpenAIRE

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 ...

Richard Dawe; Jill Marcelle-De Silva

2011-01-01

312

Thermal Conductivity of Methane-Hydrate  

OpenAIRE

The thermal conductivity of the methane hydrate CH4 (5.75 H2O) was measured in the interval 2-140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, ...

Krivchikov, A. I.; Gorodilov, B. Ya; Korolyuk, O. A.; Manzhelii, V. G.; Conrad, H.; Press, W.

2004-01-01

313

Influence of polysaccharides on cement hydration  

OpenAIRE

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...

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

2004-01-01

314

STRENGTH AND HYDRATION PROPERTIES OF CEMENT COMBINATIONS  

OpenAIRE

This paper reports the results of the laboratory studies on the standard consistence, setting times, heat of hydration and compressive strength of cement combination pastes containing Portland cement, fly ash, silica fume and metakaolin. The results show that while fly ash would reduce water demand, silica fume and metakaolin due to their fineness would result in increased water demand with increasing content. Also, while fly ash would reduce the heat of hydration, increase the setting times ...

Folagbade, Samuel Olufemi

2013-01-01

315

Confined water in the low hydration regime  

OpenAIRE

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 ...

Gallo, P.; Rapinesi, M.; Rovere, M.

2002-01-01

316

Gypsum hydration: a theoretical and experimental study  

OpenAIRE

Calcium sulphate dihydrate (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in two formations of ?- and ?-type. Among them ?-hemihydrate is mainly used to produce gypsum plasterboard since the hydration product of the ?-hemihydrate is too brittle to be used as building material /10/. This article addresses the hydration of hemihydrate since it determines the properties of gypsum and it is...

Yu, Q. L.; Brouwers, H. J. H.; Korte, A. C. J.

2009-01-01

317

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

Scientific Electronic Library Online (English)

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.

MANUEL ALEJANDRO, GIRALDO M..

2006-03-01

318

Exploration of gas hydrates. Geophysical techniques  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are ice-like crystalline substances that form a rigid cage of water molecules and entrap hydrocarbon and non-hydrocarbon gas by hydrogen bonding. Natural gas hydrate is primarily composed of water and methane. These are solid, crystalline, ice-like substances found in permafrost areas and deepwater basins around the world. They naturally occur in the pore space of marine sediments, where appropriate high pressure and low temperature conditions exist in an adequate supply of gas (mainly methane). Gas hydrates are considered as a potential non conventional energy resource. Methane hydrates are also recognized as, an influence on offshore platform stability, a major factor in climate change contributing to global warming and a significant contribution to the ocean carbon cycle. The proposed book treats various geophysical techniques in order to quantify the gas hydrate reserves and their impact on environment. The primary goal of this book is to provide the state of art for gas hydrate exploration. The target audiences for this book are non-specialist from different branches of science, graduate students and researchers. (orig.)

Thakur, Naresh Kumar [National Geophysical Research Institute, Hyderabad (India); Rajput, Sanjeev [CSIRO Petroleum Resoureces ARRC, Perth (Australia)

2011-07-01

319

Clathrate hydrates in the solar system  

Science.gov (United States)

Clathrate hydrates are crystalline compounds in which an expanded ice lattice forms cages that contain gas molecules. There are two principal hydrate structures. Structure I, with a 12 A cubic unit cell, contains 46 water molecules and 8 cages of two types, giving an ideal formula (for CH4) of CH4.5.75H2O. The actual formula contains somewhat more water as the cages are not completely filled. Other examples that form Structure I hydrates are C2H6, C2H4, C2H2, CO2, SO2, OCS, Xe, H2S. Structure II, with a 17 A cubic unit cell, contains 136 water molecules, and 8 large and 16 small cages. The ideal formula for CHCl3 is CHCL3.17H2O. Other examples of Structure II hydrates include C3H8, C2H5Cl, acetone, and tetrahydrofuran. Small molecules such as Ar, Kr and probably N2 and O2 also form a Structure II hydrate. The small molecules occupy both the large and small cages, giving an ideal formula of Ar.5.67H2O. The conditions of pressure and temperature for hydrate formation are discussed.

Miller, S. L.

1985-01-01

320

Measurement of clathrate hydrates via Raman spectroscopy  

Science.gov (United States)

Raman spectra of clathrate hydrate guest molecules are presented for three known structures (I (sI), II (sII), and H (sH)) in the following systems: CH4 (sI), CO2 (sI), C3H8 (sII), CH4 + CO2 (sI), CD4 + C3H8 (sII), CH4 + N2 (sI), CH4 + THF-d8 (sII), and CH4 + C7D14 (sH). Relative occupancy of CH4 in the large and small cavities of sI were determined by deconvoluting the ??1 symmetric bands, resulting in hydration numbers of 6.04 ?? 0.03. The frequency of the ??1 bands for CH4 in structures I, II, and H differ statistically, so that Raman spectroscopy is a potential tool to identify hydrate crystal structure. Hydrate guest compositions were also measured for two vapor compositions of the CH4 + CO2 system, and they compared favorably with predictions. The large cavities were measured to be almost fully occupied by CH4 and CO2, whereas only a small fraction of the small cavities are occupied by CH4. No CO2 was found in the small cavities. Hydration numbers from 7.27 to 7.45 were calculated for the mixed hydrate.

Sum, A.K.; Burruss, R.C.; Sloan, E.D., Jr.

1997-01-01

321

Natural gas hydrate production with seawater  

Energy Technology Data Exchange (ETDEWEB)

A system for producing natural gas hydrate (NGH) pellets from seawater was investigated. The system was comprised of a high-speed NGH production apparatus with a salt-removing apparatus to improve the stability of the NGH pellets. A pressure-induced crystallization method was used to form the gas hydrate crystals with salt water. Salt was removed from the frozen pellets with a counter wash column. Experiments were conducted to assess the effect of salt on the composition, generation, and dissociation of NGHs. A hydrate formation test was conducted to assess the relation between the gas hydrate formation rate and degree of supercooling, as well as the relation between gas hydrate formation rate and stirring revolution number. Results suggested that the stirring blade shape is an important factor in ensuring the high-speed production of hydrates with high levels of integrity. Tests confirmed that the new system was capable of producing NGH using the seawater. It was concluded that the integrity of pellets produced using the system were as high as pellets produced with fresh water. The system is currently being optimized for commercial-scale production. 7 refs., 15 figs.

Yamaguchi, H.; Takano, O.; Omori, H. [Akishima Laboratories Inc., Tokyo (Japan); Yamamoto, Y.; Kawamura, T. [National Inst. of Advanced Industrial Science and Technology, Ibaraki (Japan). Methane Hydrate Research Laboratory

2008-07-01

322

Therapeutic mineral waters  

Directory of Open Access Journals (Sweden)

Full Text Available Mineral waters meet at least one of these conditions:-mineral salt content of over 1 g/l;-the presence of a minerals with a known pharmacological action; -dissolved gas content with biological effects at concentrations of 1000 mg/l CO2, 1 mg/l H2S;-temperatures above 20ºC, independent of mineral content – thermal waters;-the existence of a scientifically recognized therapeutic action, a situation that gives these therapeutic mineral waters status of medicine, any modification by addition or removal of substances in addition to CO2 is prohibited.

Munteanu Constantin

2011-05-01

323

Therapeutic mineral waters  

OpenAIRE

Mineral waters meet at least one of these conditions:-mineral salt content of over 1 g/l;-the presence of a minerals with a known pharmacological action; -dissolved gas content with biological effects at concentrations of 1000 mg/l CO2, 1 mg/l H2S;-temperatures above 20ºC, independent of mineral content – thermal waters;-the existence of a scientifically recognized therapeutic action, a situation that gives these therapeutic mineral waters status of medicine, any modification by addition ...

Munteanu Constantin

2011-01-01

324

Additional studies on mixed uranyl oxide-hydroxide hydrate alteration products of uraninite from the palermo and ruggles granitic pegmatites, grafton county, New Hampshire  

Science.gov (United States)

Additional studies on an incompletely characterized secondary uranium "mineral" from the Ruggles and Palermo granitic pegmatites, New Hampshire, referred to as mineral "A" by Frondel (1956), reveal a mixture of schoepite-group minerals and related uranyl oxide-hydroxide hydrated compounds. A composite chemical analysis yielded (in wt.%): PbO 4.85 (EMP), UO3 83.5 (EMP), BaO 0.675 (av. of EMP and ICP), CaO 0.167 (av. of EMP and ICP), K2O 2.455 (av. of EMP and ICP), SrO 0.21 (ICP), ThO2 0.85 (ICP), H2O 6.9, ??99.61. Powder-diffraction X-ray studies indicate a close resemblance in patterns between mineral "A" and several uranyl oxide-hydroxide hydrated minerals, including the schoepite family of minerals and UO2(OH)2. The powder-diffraction data for mineral "A" are most similar to those for synthetic UO2.86??1.5H2O and UO2(OH)2, but other phases are likely present as well. TGA analysis of both mineral "A" and metaschoepite show similar weight-loss and first derivative curves. The dominant losses are at 100??C, with secondary events at 400?? and 600??C. IR spectra show the presence of (OH) and H2O. Uraninite from both pegmatites, analyzed by LAM-ICP-MS, shows the presence of Th, Pb, K and Ca.

Foord, E.E.; Korzeb, S.L.; Lichte, F.E.; Fitzpatrick, J.J.

1997-01-01

325

Resolving anisotropic distributions of correlated vibrational motion in protein hydration water  

Science.gov (United States)

In this study, we analyze correlations of vibrational motion on the surface of a small globular protein and in its hydration shell. In contrast to single particle hydration water dynamics, which are perturbed by interactions with the protein solute only in the first few hydration layers, we find that correlated, collective motions extend into the surrounding solvent on a 10 Å length scale, specifically at far-infrared frequencies below 100 cm-1. As a function of frequency, we analyze the distribution of correlated longitudinal motions in the three-dimensional environment of the protein solute, as well as in the vicinity of different protein-water interfaces. An anisotropic distribution of these correlations is observed, which is related to specific protein-water vibrations and interactions at the interfaces, as well as flexibilities of solvent exposed sites. Our results show that coupling of protein and water dynamics leaves a three-dimensional imprint in the collective dynamics of its hydration shell, and we discuss potential implications for biomolecular function, e.g., molecular recognition and binding, and the dynamical coupling of proteins to their native solvation environment.

Heyden, Matthias

2014-12-01

326

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)

327

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.)

328

Chelated minerals for poultry  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

SL, Vieira.

2008-06-01

329

Chelated minerals for poultry  

Directory of Open Access Journals (Sweden)

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 poultry 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.

SL Vieira

2008-06-01

330

Origin and evolution of fracture-hosted methane hydrate deposits  

Science.gov (United States)

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

Daigle, Hugh; Dugan, Brandon

2010-11-01

331

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

OpenAIRE

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 ...

Carroll Susan A; Maxwell Robert S; Houston Jacqueline R

2009-01-01

332

Rate of CO2 attack on hydrated Class H well cement under geologic sequestration conditions.  

Science.gov (United States)

Experiments were conducted to study the degradation of hardened cement paste due to exposure to CO2 and brine under geologic sequestration conditions (T = 50 degrees C and 30.3 MPa). The goal was to determine the rate of reaction of hydrated cement exposed to supercritical CO2 and to CO2-saturated brine to assess the potential impact of degradation in existing wells on CO2 storage integrity. Two different forms of chemical alteration were observed. The supercritical CO2 alteration of cement was similar in process to cement in contact with atmospheric CO2 (ordinary carbonation), while alteration of cement exposed to CO2-saturated brine was typical of acid attack on cement. Extrapolation of the hydrated cement alteration rate measured for 1 year indicates a penetration depth range of 1.00 +/- 0.07 mm for the CO2-saturated brine and 1.68 +/- 0.24 mm for the supercritical CO2 after 30 years. These penetration depths are consistent with observations of field samples from an enhanced oil recovery site after 30 years of exposure to CO2-saturated brine under similar temperature and pressure conditions. These results suggest that significant degradation due to matrix diffusion of CO2 in intact Class H neat hydrated cement is unlikely on time scales of decades. PMID:18767693

Kutchko, Barbara G; Strazisar, Brian R; Lowry, Gregory V; Dzombak, David A; Thaulow, Niels

2008-08-15

333

Geophysical and geotechnical properties of near-seafloor sediments in the northern Gulf of Mexico gas hydrate province  

Science.gov (United States)

Relatively few studies have focused on the geotechnical properties of near-seafloor (uppermost 10 m) sediments that are encountered during shallow coring or the initial phases of seafloor drilling. Such sediments are of particular interest in areas strongly affected by salt tectonics or the occurrence of shallow gas hydrates. Using sediment cores obtained at three gas hydrate and/or mud volcano sites in the northern Gulf of Mexico (Garden Banks GB425, Mississippi Canyon MC852, and Green Canyon GC185), we report on visual observations of gas hydrate, oil, and authigenic carbonates; index properties (grain size characteristics, specific surface, pH, Atterberg limits, water content/porosity); small-strain (shear wave velocity) and large-strain (undrained shear strength) mechanical properties; and electrical properties (dielectric permittivity, electrical conductivity). At all sites, sediments are dominated by clay minerals (probably illite) and the highest proportion of carbonate (up to 72%) occurs near the apparent central vent of the mud mound at MC852. Based on the synthesis of several types of data, we conclude that the strength, stiffness, and porosity of the near-seafloor sediments are governed not by overburden vertical effective stress, but rather by interparticle forces arising from the interaction of the ionic pore fluid with the high specific surface (53 to 76 m 2 g - 1 ) sediment grains. In some of the shallow sediments, pore water ionic concentrations significantly exceed seawater, suggesting transport of brines from deeper salt bodies. Particle-level processes, including those associated with these high ionic concentrations, lead to a mechanistic explanation for the moussey sediment texture widely observed in cores that have experienced the dissociation of gas hydrates. Electrical conductivity measurements acquired at millimeter resolution near dissociating gas hydrate indicate that, prior to hydrate dissociation, the pore fluids are in equilibrium with those distal from the hydrate.

Francisca, F.; Yun, T.-S.; Ruppel, C.; Santamarina, J. C.

2005-09-01

334

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

335

Controls on Gas Hydrate Formation and Dissociation  

Energy Technology Data Exchange (ETDEWEB)

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.

Miriam Kastner; Ian MacDonald

2006-03-03

336

Epidemiological significance of mineral fiber persistence in human lung tissue.  

OpenAIRE

For the experimentalist, mineral fiber persistence may provide clues to disease mechanisms, for the epidemiologist, to the measurement of exposure. Qualitatively, this can be valuable when unsuspected exposures have been demonstrated as, for example, MMMF workers exposed to amosite or chrysotile workers to tremolite. Quantitatively, the potential of lung burden analyses to assess lifetime mineral fiber exposure has yet to be achieved with confidence. The difficulties are 2-fold, the first rel...

Mcdonald, J. C.

1994-01-01

337

Hydration sequence of swelling clays: evolutions of specific surface area and hydration energy.  

Science.gov (United States)

In order to identify the key steps and the driving force for the hydration process of swelling clays, the water adsorption isotherms and enthalpies were measured on monoionic montmorillonite samples saturated with alkali or calcium ions, and on bi-ionic samples saturated with a sodium-calcium mixture. The specific surface area evolution along the hydration process was determined using a recent interpretation of the experimental adsorption isotherms of swelling solids. Results are interpreted in structural terms. Compared with additional data from sample-controlled thermal analysis (SCTA), the results confirm experimentally that the hydration of Li- and Na-montmorillonite is mainly a cation-controlled process, in contrast with the hydration of Cs samples in which the cation contribution to hydration is negligible, as we have already demonstrated using electrostatic calculations or conductivity measurements. PMID:19303602

Salles, Fabrice; Douillard, Jean-Marc; Denoyel, Renaud; Bildstein, Olivier; Jullien, Michel; Beurroies, Isabelle; Van Damme, Henri

2009-05-15

338

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

Directory of Open Access Journals (Sweden)

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.

O. Nashed

2014-01-01

339

Hydration sequence of swelling clays: Evolutions of specific surface area and hydration energy  

International Nuclear Information System (INIS)

In order to identify the key steps and the driving force for the hydration process of swelling clays, the water adsorption isotherms and enthalpies were measured on mono-ionic montmorillonite samples saturated with alkali or calcium ions, and on bi-ionic samples saturated with a sodium-calcium mixture. The specific surface area evolution along the hydration process was determined using a recent interpretation of the experimental adsorption isotherms of swelling solids. Results are interpreted in structural terms. Compared with additional data from sample-controlled thermal analysis (SCTA), the results confirm experimentally that the hydration of Li- and Na-montmorillonite is mainly a cation-controlled process, in contrast with the hydration of Cs samples in which the cation contribution to hydration is negligible, as we have already demonstrated using electrostatic calculations or conductivity measurements. (authors)

340

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

Science.gov (United States)

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.

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

2012-12-01

341

Recommended nomenclature for zeolite minerals: report of the subcommittee on zeolites of the International Mineralogical Association, Commission of New Minerals and Mineral Names  

Science.gov (United States)

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission of New Minerals and Mineral Names. In a working definition of a zeolite mineral used for review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundance in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si:Al ratio except for heulandite (Si:Al < 4.0) and clinoptilolite (Si:Al ??? 4.0). Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term 'ideal formula' should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr.-Ba: chabazite-Ca.-Na.-K; clinoptilolite-K, -Na, -Ca: dachiardite-Ca, -Na; erionite-K, -Ca: faujasite-Na, -Ca, -Na: paulingite-K. -Ca; phillipsite-Na, -Ca, -Ka; stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data. IZA structure-type symbols, space-group symmetry; unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.

Coombs, D.S.; Alberti, A.; Armbruster, T.; Artioli, G.; Colella, C.; Galli, E.; Grice, J.D.; Liebau, F.; Mandarino, J.A.; Minato, H.; Nickel, E.H.; Passaglia, E.; Peacor, D.R.; Quartieri, S.; Rinaldi, R.; Ross, M.; Sheppard, R.A.; Tillmanns, E.; Vezzalini, G.

1998-01-01

342

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%)

343

Complex admixtures of clathrate hydrates in a water desalination method  

Science.gov (United States)

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.

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

2009-07-14

344

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom part of the Ugnu and throughout the West Sak. No hydrate-bearing zones were identified either in recovered core or on well logs. The base of the permafrost was found at about 1260 ft. With the exception of the deepest sands in the West Sak and some anomalous thin, tight zones, all sands recovered (after thawing) are unconsolidated with high porosity and high permeability. At 800 psi, Ugnu sands have an average porosity of 39.3% and geometrical mean permeability of 3.7 Darcys. Average grain density is 2.64 g/cc. West Sak sands have an average porosity of 35.5%, geometrical mean permeability of 0.3 Darcys, and average grain density of 2.70 g/cc. There were several 1-2 ft intervals of carbonate-cemented sandstone recovered from the West Sak. These intervals have porosities of only a few percent and very low permeability. On a well log they appear as resistive with a high sonic velocity. In shallow sections of other wells these usually are the only logs available. Given the presence of gas in Hot Ice No. 1, if only resistivity and sonic logs and a mud log had been available, tight sand zones may have been interpreted as containing hydrates. Although this finding does not imply that all previously mapped hydrate zones are merely tight sands, it does add a note of caution to the practice of interpreting the presence of hydrates from old well information. The methane hydrate stability zone below the Hot Ice No. 1 location includes thick sections of sandstone and conglomerate which would make excellent reservoir rocks for hydrates and below the permafrost zone shallow gas. The Ugnu formation comprises a more sand-rich section than does the West Sak formation, and the Ugnu sands when cleaned and dried are slightly more porous and significantly more permeable than the West Sak.

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

2005-02-01

345

Gas hydrates: past and future geohazard?  

Science.gov (United States)

Gas hydrates are ice-like deposits containing a mixture of water and gas; the most common gas is methane. Gas hydrates are stable under high pressures and relatively low temperatures and are found underneath the oceans and in permafrost regions. Estimates range from 500 to 10,000 giga tonnes of carbon (best current estimate 1600-2000 GtC) stored in ocean sediments and 400 GtC in Arctic permafrost. Gas hydrates may pose a serious geohazard in the near future owing to the adverse effects of global warming on the stability of gas hydrate deposits both in ocean sediments and in permafrost. It is still unknown whether future ocean warming could lead to significant methane release, as thermal penetration of marine sediments to the clathrate-gas interface could be slow enough to allow a new equilibrium to occur without any gas escaping. Even if methane gas does escape, it is still unclear how much of this could be oxidized in the overlying ocean. Models of the global inventory of hydrates and trapped methane bubbles suggest that a global 3( degrees )C warming could release between 35 and 940 GtC, which could add up to an additional 0.5( degrees )C to global warming. The destabilization of gas hydrate reserves in permafrost areas is more certain as climate models predict that high-latitude regions will be disproportionately affected by global warming with temperature increases of over 12( degrees )C predicted for much of North America and Northern Asia. Our current estimates of gas hydrate storage in the Arctic region are, however, extremely poor and non-existent for Antarctica. The shrinking of both the Greenland and Antarctic ice sheets in response to regional warming may also lead to destabilization of gas hydrates. As ice sheets shrink, the weight removed allows the coastal region and adjacent continental slope to rise through isostacy. This removal of hydrostatic pressure could destabilize gas hydrates, leading to massive slope failure, and may increase the risk of tsunamis. PMID:20403833

Maslin, Mark; Owen, Matthew; Betts, Richard; Day, Simon; Dunkley Jones, Tom; Ridgwell, Andrew

2010-05-28

346

Formation and blockage of HCFC-141B hydrate in pipeline  

Energy Technology Data Exchange (ETDEWEB)

Hydrates are ice-like crystalline compounds that may form in offshore condensate pipeline running at high pressures and low temperatures. Pressure drops in pipelines can plug the pipeline or destroy equipment downstream when hydrates form in a pipeline. In order to prevent the formation of plugs and run pipeline systems safely, it is necessary to understand the flow characters of hydrates slurry in pipelines. This paper presented a study that examined the flow characteristics of a hydrate slurry in a newly built loop which consisted of a 42 mm diameter stainless pipe, 30 metres long. Changes of parameters in the blocking process of hydrate in the pipeline, such as pressure, pressure drop, temperature were analyzed. The hydrate volume concentration of transition from slurry-like hydrates to slush-like hydrates was suggested as the mark to judge if the pipeline runs safely or not. HCFC-141b hydrate slurry was used as the hydrate in the experiment. The paper described the experimental apparatus and protocol as well as the results and conclusions of the study. It was concluded that flowing could accelerate the forming of hydrate in pipeline and that the pressure drops increased quickly when the slush-like hydrates occurred with a hydrate volume concentration reaching as large as 40 per cent, which meant the pipeline entered a dangerous running zone and should be avoided. 10 refs., 6 figs.

Wuchang, W.; Deqing, L. [Chinese Academy of Sciences, Wushan, Tianhe District (China). Guangzhou Inst. of Energy Conversion; Shuanshi, F. [South China Univ. of Technology, Tianhe District, Guangzhou (China). School of Chemical and Energy Engineering

2008-07-01

347

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

OpenAIRE

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...

Birkedal, Knut Arne

2009-01-01

348

Novel hydrogen hydrate structures under pressure.  

Science.gov (United States)

Gas hydrates are systems of prime importance. In particular, hydrogen hydrates are potential materials of icy satellites and comets, and may be used for hydrogen storage. We explore the H?O-H? system at pressures in the range 0-100 GPa with ab initio variable-composition evolutionary simulations. According to our calculation and previous experiments, the H?O-H? system undergoes a series of transformations with pressure, and adopts the known open-network clathrate structures (sII, C?), dense "filled ice" structures (C?, C?) and two novel hydrate phases. One of these is based on the hexagonal ice framework and has the same H?O:H? ratio (2:1) as the C? phase at low pressures and similar enthalpy (we name this phase Ih-C?). The other newly predicted hydrate phase has a 1:2 H?O:H? ratio and structure based on cubic ice. This phase (which we name C?) is predicted to be thermodynamically stable above 38 GPa when including van der Waals interactions and zero-point vibrational energy, and explains previously mysterious experimental X-ray diffraction and Raman measurements. This is the hydrogen-richest hydrate and this phase has a remarkable gravimetric density (18 wt.%) of easily extractable hydrogen. PMID:25001502

Qian, Guang-Rui; Lyakhov, Andriy O; Zhu, Qiang; Oganov, Artem R; Dong, Xiao

2014-01-01

349

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)

350

Novel Hydrogen Hydrate Structures under Pressure  

Science.gov (United States)

Gas hydrates are systems of prime importance. In particular, hydrogen hydrates are potential materials of icy satellites and comets, and may be used for hydrogen storage. We explore the H2O-H2 system at pressures in the range 0-100 GPa with ab initio variable-composition evolutionary simulations. According to our calculation and previous experiments, the H2O-H2 system undergoes a series of transformations with pressure, and adopts the known open-network clathrate structures (sII, C0), dense ``filled ice'' structures (C1, C2) and two novel hydrate phases. One of these is based on the hexagonal ice framework and has the same H2O:H2 ratio (2:1) as the C0 phase at low pressures and similar enthalpy (we name this phase Ih-C0). The other newly predicted hydrate phase has a 1:2 H2O:H2 ratio and structure based on cubic ice. This phase (which we name C3) is predicted to be thermodynamically stable above 38 GPa when including van der Waals interactions and zero-point vibrational energy, and explains previously mysterious experimental X-ray diffraction and Raman measurements. This is the hydrogen-richest hydrate and this phase has a remarkable gravimetric density (18 wt.%) of easily extractable hydrogen.

Qian, Guang-Rui; Lyakhov, Andriy O.; Zhu, Qiang; Oganov, Artem R.; Dong, Xiao

2014-07-01

351

Hydrate melting in soil around hot conductor  

Energy Technology Data Exchange (ETDEWEB)

There is ice in the Gulf of Mexico, and this type of ice called gas hydrates burns when ignited. Gas hydrates form slowly within the soil mass when the gas seeping up from offshore oil reservoirs mixes with water under high pressures (>500 m of water) and low temperatures (a few degrees Celsius). The oil travels from the well to the platform through a conductor pipe. The oil and therefore the conductor are very hot and melt the existing hydrates that are within the depth of the foundation piles. The melting process generates a large amount of gas that can endanger the stability of the foundation. The rate at which the temperature rises around the hot conductor in the hydrate rich soil is studied using the finite-element method (FEM). A detailed thermodynamic analysis is performed. It includes a laboratory experiment to help validate FEM, a study of the mesh size, the thermodynamic analysis results, a study of the conductor size, and of the latent heat influence. The results can be used to evaluate the temperature rise around a hot pipe buried in soil and therefore the propagation of the hydrate melting front around the conductor and toward the piles.

Briaud, J.L. [Texas A and M Univ., College Station, TX (United States). Dept. of Civil Engineering; Chaouch, A. [ATSER Engineering and Environmental Co., Houston, TX (United States)

1997-07-01

352

Hydration shells exchange charge with their protein  

DEFF Research Database (Denmark)

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.

Abitan, Haim; Lindgård, Per-Anker

2010-01-01

353

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)

354

Hydration of refractory cements, with spinel phase generated in-situ  

International Nuclear Information System (INIS)

High alumina refractory materials with additions of synthetic spinel (MgAl2O4) have good thermo mechanical and attack from slag properties, which are useful in many technological applications. The spinel phase generated in-situ, MA, has proven to be a suitable and economic alternative to the use of sintered or electrocast spinels. Prior studies have established synthesis conditions for refractory cements with the spinel phase generated in-situ (CCAMA) starting with alumina mixtures and Buenos Aires dolomites. The binding properties of the aluminous cements depend on the hydrated calcium aluminates that form in the setting and hardening stages of the pastes. To avoid breaks, the refractory material must undergo programmed heating before reaching the serviceable temperature. It should also include the present phases and the transformations that occur at different temperatures. In this context knowledge about the green mineral composition and its response to an increase in temperature is especially important. This work presents studies to define the composition of CCAMA cement mortars at different hydration ages, and to estimate phase proportions and behavior during dehydration. DRX and FTIR techniques are applied in order to follow the structural changes that take place during the hydration process. The evolution of the dehydration is also studied, mostly using FTIR. The mortars were prepared with a water/cement ration of 0.5, recommended for this ement ration of 0.5, recommended for this kind of work. The hydration was carried out at room temperature and samples were analyzed at the following ages: 15 min.; 1 h.; 1, 3, 7, 14, 28, 60 and 90 days. With the results the evolution of the phases as a function of the age of the hydration were studied. The main hydrate that was formed was CAH10, with a significantly increased proportion during the first 14 days of hydration. Its carbonation was also observed by the presence of calcium carboaluminates and the formation of gibbsite. The MA phase is also confirmed to be hydraulically inert. The FTIR studies are an especially useful tool for establishing dehydration temperatures and the decomposition of the carboaluminates. These studies are the basis for further research on the mechanical properties as well as on the drying and utilization of these materials

355

Mineral Classification Exercise  

Science.gov (United States)

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.

Dexter Perkins

356

USGS: Mineral Resources Program  

Science.gov (United States)

"The Mineral Resources Program funds science to provide and communicate current, impartial information on the occurrence, quality, quantity, and availability of mineral resources." This website divides the mineral resource information, project descriptions, and products for the United States into four main regional categories: Eastern, Central, Western, and Alaska. Researchers can discover new grant opportunities and can obtain access to the National Geochemical Survey's database. Students and educators can find statistics and information on how the United State's supply-and-demand for minerals and materials affects the economy, security, and environment.

357

Comparison on Heat of Hydration between Current Concrete for NPP and High Fluidity Concrete including Pozzolan Powders  

International Nuclear Information System (INIS)

Nuclear power plant (NPP) concrete structures are exposed to many construction factors that lower the quality of concrete due to densely packed reinforcements and heat of hydration since they are mostly constructed with mass concrete. The concrete currently being used in Korean NPPs is mixed with Type I cement and fly ash. However, there is a demand to improve the performance of concrete with reduced heat of hydration and superior constructability. Many advantages such as improving workability and durability of concrete and decreasing heat of hydration are introduced by replacing cement with pozzolan binders. Therefore, the manufacturing possibility of high fluidity concrete should be investigated through applying multi-component powders blended with pozzolan binders to the concrete structure of NPPs, while the researches on properties, characteristic of hydration, durability and long-term behavior of high fluidity concrete using multi-component cement should be carried out. High fluidity concrete which is made using portland cement and pozzlonan powders such as fly ash and blast furnace slag has better properties on heat of hydration than the concrete currently in use for NPPs

358

Effects of CO2 Hydrate on Deep-Sea Foraminiferal Assemblages  

Energy Technology Data Exchange (ETDEWEB)

THE EFFECTS OF CO2 HYDRATE ON DEEP-SEA FORAMINIFERAL ASSEMBLAGES E. R. Ricketts*, J. P. Kennett and T. M. Hill Department of Geological Sciences University of California, Santa Barbara, CA USA Jim Barry Monterey Bay Aquarium Research Institute Moss Landing, CA USA ABSTRACT This study, conducted with the Monterey Bay Aquarium Research Institute (MBARI), is the first to investigate potential effects of CO2 hydrates on benthic microfossils, specifically foraminifera. 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 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 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.

Ricketts, E R; Kennett, J P; Hill, T M; Barry, J P

2005-06-01

359

A study of the mortality of Cornish tin miners  

International Nuclear Information System (INIS)

Increased mortality from cancer of the lung has been found in several studies of miners exposed to high levels of radioactivity in underground air. In view of their exposure to raised levels of radiation, we have studied the mortality of a group of men recorded as Cornish tin miners in 1939. Using occupational description, a crude classification of exposure was derived for these miners. The meaningfulness of this classification was supported by differences in mortality from silicosis and silicotuberculosis. A twofold excess of cancer of the lung was found for underground miners, while for other categories mortality from this cause was less than expected. This supports the findings of previous studies on exposure to radon and its daughters. An excess of cancer of the stomach was also observed among underground miners. (author)

360

Intermolecular Hydrogen Transfer in Isobutane Hydrate  

Directory of Open Access Journals (Sweden)

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.

Takeshi Sugahara

2012-05-01

361

Fuel cell membrane hydration and fluid metering  

Science.gov (United States)

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).

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

2003-01-01

362

Experimental Study of Metastability of Gas Hydrate in Frozen Sediments  

Science.gov (United States)

The stability zone of natural gas hydrates formations in cryolitozone where methane gas hydrates can be formed and exist, begins with depths of 200-250 meters and extends in sub-permafrost layers up to depths of 800-1500 meters. Recently obtained data allow to consider methane gas hydrates existence in thicknesses of frozen sediments above zone of its thermodynamic stability (up to depths of 200-250 meters) This zone may be called the zone of gas hydrate's metastability or zone of "relict hydrate" existence. The relict natural gas hydrate accumulations in permafrost may have formed under favorable thermodynamic conditions during glacial periods. Subsequently, glacial retreat induced metastable hydrate preservation due to self-preservation effect. At present the existence of natural gas hydrates at shallow depth at nonequilibrium conditions leads to a serious geological hazard during exploration drilling. The dissociation of shallow metastable methane hydrate may contribute to global warming by adding significant amount of a greenhouse gas (methane) to the atmosphere. Up to now relict natural gas hydrates are poorly understood, so the experimental research of gas hydrates decomposition in frozen sediments under non-equilibrium conditions is of significant importance. The experimental technique included the following stages: i) artificial saturation of sediments by methane or carbon dioxide hydrates, ii) freezing of the hydrate-containing samples, iii) studying of the hydrate decomposition process including self-preservation in frozen samples after the reducing gas pressure below line of three phase equilibrium (gaseous phase - gas hydrate - ice). Core samples of different composition and porous structure recovered from gas-showing horizons of permafrost sediments were used. Experimental data on the influence of temperature, pressure, hydrate- and ice-saturation on the kinetics of methane gas hydrates dissociation in natural sediments from permafrost zone was obtained. The experiments show that self-preservation of gas hydrates in frozen sediments is enhanced by low temperatures, high ice content, and low sediment gas permeability. Residual (preserved) hydrate saturation of frozen samples after pressure release below equilibrium reached 20-25%. Experimental researches on kinetics of gas hydrate dissociation in frozen sediments samples selected from gas showing horizons in permafrost confirm the opportunity of long preservation of pore methane gas hydrate in frozen sediments at negative temperatures and pressures below equilibrium due to self-preservation effect. Relic gas hydrates could be source of significant methane emission from shallow permafrost at rise of temperature and thawing.

Chuvilin, E. M.; Buhanov, B. A.; Guryeva, O. M.; Istomin, V. A.; Takeya, S.; Hachikubo, A.

2011-12-01

363

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.)

364

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

365

Recovery of gas from hydrate deposits using conventional production technology  

Science.gov (United States)

Methane hydrate gas could be a sizeable energy resource if methods can be devised to produce this gas economically. This paper examines two methods of producing gas from hydrate deposits by the injection of hot water or steam, and also examines the feasibility of hydraulic fracturing and pressure reduction as a hydrate gas production technique. A hydraulic fracturing technique suitable for hydrate reservoirs is also described.

McGuire, P. L.

366

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

367

NMR study of seed hydration with deuterated water: Dependence of proton signals on hydration level  

International Nuclear Information System (INIS)

Proton NMR signals in seeds are shown to depend on hydration level. In fact at low water amount, as it occurs in many native seeds, protons can have a restricted mobility and are not detectable. A NMR method for measuring the dependence of proton signals on hydration is reported. The method also allows the separation of the contributions of water and non-water protons in a low-resolution NMR experiment. It is based on successive hydrations (with deuterated water) - desiccation steps and on the analysis of the transverse magnetization decay curves

368

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

Science.gov (United States)

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.

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

2003-04-01

369

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

Science.gov (United States)

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.

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

1981-01-01

370

Nanostructure of Calcium Silicate Hydrates in Cements  

Science.gov (United States)

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

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

2010-05-01

371

Simulation of subsea gas hydrate exploitation  

Science.gov (United States)

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

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

2014-05-01

372

Structure of nanocrystalline calcium silicate hydrates  

OpenAIRE

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...

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

2014-01-01

373

Hydrate Technology For Transporting Natural Gas  

OpenAIRE

Natural gas hydrate (NGH) is a viable alternative to LNG (Liquefied Natural Gas) or pipelines for the transportation of natural gas from source to demand. It involves three stages: production, transportation and re-gasification. The production of the hydrate occurs at pressures >50 bar at temperatures ~10oC in the presence of water and natural gas (particularly methane, ethane, propane). Transportation is by insulated bulk carrier at around –5 oC and atmospheric pressure or 0 oC at 10 bar, ...

Dawe, R. A.

2003-01-01

374

Temperature-dependent dielectric properties of slightly hydrated horn keratin.  

Science.gov (United States)

With an aim to reveal the mechanism of protein-water interaction in a predominantly two phase model protein system this study investigates the frequency and temperature dependence of dielectric constant epsilon' and loss factor epsilon'' in cow horn keratin in the frequency range 30 Hz to 3 MHz and temperature range 30-200 degrees C at two levels of hydration. These two levels of hydration were achieved by exposing the sample to air at 50% relative humidity (RH) at ambient temperature and by evacuating the sample for 72 h at 105 degrees C. A low frequency dispersion (LFD) and an intermediate frequency alpha-dispersion were the two main dielectric responses observed in the air-dried sample. The LFD and the high frequency arm of the alpha-dispersion followed the same fractional power law of frequency. Within the framework of percolation cluster model these dispersions, respectively have been attributed to percolation of protons between and within the clusters of hydrogen-bonded water molecules bound to polar or ionizable protein components. The alpha-dispersion peak, which results from intra-cluster charge percolation conformed to Cole-Cole modified Debye equation. Temperature dependence of the dielectric constant in the air-dried sample exhibited peaks at 120 and 155 degrees C which have been identified as temperatures of onset of release of water bound to polar protein components in the amorphous and crystalline regions, respectively. An overall rise in the permittivity was observed above 175 degrees C, which has been identified as the onset of chain melting in the crystalline region of the protein. PMID:18275998

Rizvi, Tasneem Zahra; Khan, Muhammad Abdullah

2008-04-01

375

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

Science.gov (United States)

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.

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

1995-07-01

376

The mineral sources of Shugnan district  

International Nuclear Information System (INIS)

In this chapter of book authors describe such mineral sources of Shugnan district as Mineral source Rivak, Mineral source Nemats, Mineral source Tokuzbulak (on the valley of River Tokuzbulak), Mineral source Djelandi, Mineral source Koytezak, Mineral source Kauk (on the valley of river Gunt), Mineral source Vezdara (on the valley of River Vezdara), Mineral source Shokhdara, mineral source Djaushangoz (on the River Djaushangoz), Mineral source Naspar, Mineral source Kokbay (on the head of Shokhdara River

377

Mineral Commodity Summaries 2007  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

2007-01-01

378

Mineral Commodity Summaries 2011  

Science.gov (United States)

Each chapter of the 2011 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry structure, Government programs, tariffs, 5-year salient statistics, and world production and resources. The MCS is the earliest comprehensive source of 2010 mineral production data for the world. More than 90 individual minerals and materials are covered by two-page synopses. For mineral commodities for which there is a Government stockpile, detailed information concerning the stockpile status is included in the two-page synopsis. Mineral Commodity Summaries 2011 contains new chapters on iron oxide pigments, wollastonite, and zeolites. The chapters on mica (natural), scrap and flake and mica (natural), sheet have been combined into a single chapter - mica (natural). Abbreviations and units of measure, and definitions of selected terms used in the report, are in Appendix A and Appendix B, respectively. "Appendix C - Reserves and Resources" has been divided into "Part A - Resource/Reserve Classification for Minerals" and "Part B - Sources of Reserves Data," including some information that was previously in this introduction. A directory of USGS minerals information country specialists and their responsibilities is Appendix D. The USGS continually strives to improve the value of its publications to users. Constructive comments and suggestions by readers of the MCS 2011 are welcomed.

U.S. Geological Survey

2011-01-01

379

Mineral Commodity Summaries 2006  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

2006-01-01

380

Mineral Commodity Summaries 2000  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

2000-01-01

381

Mineral Commodity Summaries 1997  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials

U.S. Geological Survey

1997-01-01

382

Mineral Commodity Summaries 2001  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

2001-01-01

383

Mineral Commodity Summaries 1999  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

1999-01-01

384

Mineral Commodity Summaries 1998  

Science.gov (United States)

Published on an annual basis, this report is the earliest Government publication to furnish estimates covering nonfuel mineral industry data. Data sheets contain information on the domestic industry structure, Government programs, tariffs, and 5-year salient statistics for over 90 individual minerals and materials.

U.S. Geological Survey

1998-01-01

385

The Miner's Canary  

Science.gov (United States)

Miners used canaries as early warning signals: when a canary gasped for breath, the miners knew there was a problem with the atmosphere in the mine. The experience of people of color in higher education can be used similarly as a diagnostic tool.

Guinier, Lani

2005-01-01

386

Standardization and software infrastructure for gas hydrate data communications  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

387

Composition Characteristics of Gas Hydrate Produced Gas and Pretreatment Research  

Directory of Open Access Journals (Sweden)

Full Text Available To accelerate the pace of research and the use of alternative energy strategies Gas Hydrate, on the basis of previous studies, this paper analyzes the composition characteristics of Gas Hydrate produced gas. It provides technical support for our research and the use of Gas Hydrate. This eases the supply and demand of energy and reduces pollution of the atmospheric environment.

Shuren Yang

2014-11-01

388

Small angle X-ray scattering from hydrating tricalcium silicate  

International Nuclear Information System (INIS)

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

389

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