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1

Stability of hydrated minerals on Mars  

Science.gov (United States)

The validity of recent identification of various hydrated minerals (kieserite, gypsum, hexahydrite, nontronite, chamosite, and montmorillonite) on Mars was assessed by exposing these minerals to simulated Martian surface conditions of atmospheric composition and pressure, temperature, and ultraviolet light irradiation. When exposed to such conditions the hydrated minerals exhibit in general, greater losses of interlayer H2O than structural OH. Minerals such as gypsum that contain structural H2O are more resistant to H2O loss than phyllosilicates. The partial loss of OH in some of the phyllosilicates is not accompanied by a measurable and systematic change in the wavelength position or intensity of metal-OH absorption bands. The characteristic absorption features that allow for identification of these minerals on Mars may be reduced in intensity, but are nevertheless largely preserved.

Cloutis, Edward A.; Craig, Michael A.; Mustard, John F.; Kruzelecky, Roman V.; Jamroz, Wes R.; Scott, Alan; Bish, David L.; Poulet, François; Bibring, Jean-Pierre; King, Penelope L.

2007-10-01

2

CO2 adhesion on hydrated mineral surfaces.  

UK PubMed Central (United Kingdom)

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 homogenous 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 nanometers. 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 three. 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 the CO2.

Wang S; Tao Z; Persily S; Clarens AF

2013-09-01

3

Hydrous silicate and salt minerals are stable in a hydrated state on the surface of Mars  

Science.gov (United States)

Mars Odyssey Neutron spectrometer data provide evidence of heterogeneous near-surface water abundances up to ˜ 10 wt% in near-equatorial regions on Mars. The fact that water ice is unstable in these regions suggests that some of this water may be present in hydrous silicates (smectites or zeolites) or hydrated salts. Zeolites (e.g., clinoptilolite and chabazite) and smectites have been suggested to occur on the martian surface, and Viking, Pathfinder, and MER chemical data support the existence of MgSO4 in altered surface materials. In addition, a variety of sulfate and chloride minerals have been identified in martian meteorite samples. Mg-sulfates exist on Earth in a variety of hydration states, including 7-hydrate (51 wt% water), 6-hydrate (47 wt% water), and monohydrate (13 wt% water), but occurrences on Mars may be very different and may include intermediate hydrates such as 5-, 4-, 3-, and 2-hydrates (43, 37, 31, and 23 wt% water, respectively). Other hydrated sulfates (e.g., gypsum, CaSO4\\cdot 2H2O, 21 wt% water) or hydrated sulfate-chloride salts may also be present based on existing chemical data. Experimental data on the thermodynamics of hydration/dehydration reactions for clinoptilolite, chabazite, and smectite show that they would be partially to completely hydrated at martian surface conditions. Their hydration enthalpies are such that they have the potential to hydrate and dehydrate during diurnal temperature cycles at the martian equator. Similar data are not available for the hydrated Mg sulfates, but controlled-atmosphere X-ray diffraction measurements on the 7-, 6-, and 1-hydrate suggest that the 7-hydrate is not stable at the low partial pressures of water found on Mars. The 6-hydrate becomes amorphous under low-pressure conditions but retains ˜ 18 wt% water; it readily rehydrates when exposed to elevated water-vapor pressure. The potential suite of hydrated silicate and salt minerals is large and requires considerable additional research. However, existing data demonstrate that several of these minerals are reasonable hosts for water molecules under present martian surface conditions. One or several of these minerals may contribute to the subsurface water observed by Mars Odyssey. Some of the hydrated Mg sulfates have such high water concentrations that realistic amounts would be required to account for the observed near-equatorial martian water.

Bish, D.; Vaniman, D.; Chipera, S.

4

Hydration status of underground miners in a temperate Australian region.  

UK PubMed Central (United Kingdom)

BACKGROUND: Dehydration is a health risk for miners in tropical regions of Australia. However, it is not known whether dehydration poses a health risk to miners working in temperate regions of Australia. METHODS: A cross-sectional study of 88 miners from two underground mines was undertaken in south-eastern New South Wales, Australia. Participants had their height, weight, waist circumference and hydration status measured and completed a self-administered questionnaire on fluid intake, access to water, and socio-demographic characteristics. Health and Safety managers were surveyed about guidelines relating to healthy work and lifestyle behaviours which impact/influence hydration. RESULTS: Hydration tests indicated that more than half of the miners (approximately 58%) were dehydrated (Urinary Specific Gravity (USG) >1.020) both before and after their shift, with three workers pre-shift and four workers post-shift displaying clinical dehydration (USG>1.030). Overall, 54.0% of participants were overweight and 36.8% were obese. Miners who commenced the shift with poor hydration status were 2.6 times more likely to end the shift with poor hydration, compared to those who commenced the shift with good hydration (OR 2.6, 95% CI 1.06, 6.44). Miners who had a mean USG result for the entire shift indicating dehydration were more likely to be obese (42.9%) and have a waist measurement in the high risk range for metabolic complications (40.8%) than those workers that were adequately hydrated for their entire shift (29.4% and 14.7% respectively). Some guidelines promoting healthy lifestyles and supportive work environments were in place, but there were limited guidelines on healthy weight and hydration. CONCLUSIONS: Dehydration, being overweight and obesity were linked issues in this cohort of miners. Strategies are needed to: adapt the workplace environment to increase water accessibility; encourage appropriate consumption of water both at work and at home; and to promote physical activity and good nutrition to maintain healthy weight.

Polkinghorne BG; Gopaldasani V; Furber S; Davies B; Flood VM

2013-01-01

5

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

6

Behaviour of hydrated minerals during their analysis by electron microprobe  

International Nuclear Information System (INIS)

The vacuum, electric fields and production of heat in the electron probe target may produce serious damages in hydrated minerals. The variation in time of apparent concentration of elements is often very important. The study of this phenomenon was undertaken on two zeolites (chabazite and stilbite) and two phosphates (vivianite and ludlamite). It is emphasized by complex movement of ions within the specimen which makes the irradiated region richer in Fe2+, Ca2+ or p5+ ions.

1985-01-01

7

Behaviour of hydrated minerals during their analysis by electron microprobe  

Energy Technology Data Exchange (ETDEWEB)

The vacuum, electric fields and production of heat in the electron probe target may produce serious damages in hydrated minerals. The variation in time of apparent concentration of elements is often very important. The study of this phenomenon was undertaken on two zeolites (chabazite and stilbite) and two phosphates (vivianite and ludlamite). It is emphasized by complex movement of ions within the specimen which makes the irradiated region richer in FeS , CaS or pV ions.

Autefage, F. (Institut National des Sciences Appliquees, 31 - Toulouse (France)); Fontan, F. (Laboratoire de Mineralogie et Cristallographie, C.N.R.S., Universite Paul-Sabatier, 31 - Toulouse (France))

1985-01-01

8

Sulfate Hydration States in Interpretation of Martian Mineral Assemblages  

Science.gov (United States)

Remote spectral data and surface-measured chemical associations with S indicate widespread distribution of Mg-, Ca-, and Fe-sulfate salts on Mars. These salts are identified at least in part as hydrates, but spectral data and the low temperatures and low pH2O of Mars suggest that hydration states vary with origin, latitude, and exposure history. An understanding of stability limits and dehydration/rehydration rates is vital to understanding occurrences that may be interpreted variously as lacustrine, alteration via groundwater or discharge with evaporation, surface weathering, thermal brine systems, eolian recycling, or others. Different sulfates on Mars have varied susceptibility to desiccation at relatively warm, low-RH conditions or to hydration at cold, high-RH conditions. This variability provides a potent tool for interpreting exposure history. Among Ca-sulfates, gypsum and insoluble anhydrite should be stable and remain, respectively, fully hydrated or water-free at most latitudes and through diurnal and seasonal cycles, but bassanite is more sensitive to transient hydration. Mg-sulfates may have various values of n in the formula MgSO4.nH2O, and rehydration of desiccated forms often produces metastable phases. At low pH2O, unlike Ca- sulfates, amorphous forms appear with low values of n dependent, in part, on temperature. Kieserite resists dehydration but may hydrate in conditions where ice is stable at the surface. Fe-sulfates have more complex dehydration and rehydration properties. Jarosite is very resilient because of the lack of H2O molecules and presence of OH. Other Fe-sulfates are not so durable, e.g., coquimbite (Fe2 (SO4)3.9H2O) has independent H2O and dehydration on heating to 30 °C produces an amorphous product that does not rehydrate. Copiapite is similarly susceptible to dehydration. Modest heating of many H2O-bearing ferric sulfates can be destructive, and degradation can produce both cemented solids and viscous liquids. Sulfate salt associations on Mars provide mineral tools to interpret depositional origins, paleohydrology, and paleoclimatology, but these tools require attention to environments of formation, stability relations, and kinetics of hydration and dehydration.

Vaniman, D. T.; Bish, D. L.

2008-12-01

9

Hydrated Mineral Stratigraphy in Ius Chasma, Valles Marineris  

Science.gov (United States)

Kieserite, a polyhydrated sulfate, hydrated silica, Fe/Mg phyllosilicate, and a hydrated silicate (possibly consistent with an acid-leached phyllosilicate) are found in light-toned units within Ius Chasma, Valles Marineris.

Roach, L. H.; Mustard, J. F.; Murchie, S. L.; Bishop, J. L.; Ehlmann, B. L.; Milliken, R. E.; Lichtenberg, K.; Parente, M.

2009-03-01

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; U. Lohmann; G. Lesins

2007-01-01

11

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 compared to unexposed montmorillonite within our experimental conditions. The percentages of active ice nuclei were 2 to 8 times higher at 90% RHw and 2 to 7 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 15°C higher than for unexposed montmorillonite particles at 90% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 10°C warmer than unexposed montmorillonite at 90% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles suggesting that the ammonia is chemically bound to the montmorillonite particle. 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; U. Lohmann; G. Lesins

2007-01-01

12

Sulfates and Other Hydrated Minerals in Ius Chasma, Valles Marineris and Implications for Water Geochemistry  

Science.gov (United States)

Ius Chasma is a linear trough in western Valles Marineris containing horst and graben structures, multiple landslides, and light-toned floor deposits. Elsewhere is Valles Marineris, sulfate deposits identified by OMEGA and CRISM are restricted to Interior Layered Deposits or nearby autochthonous loose material (Gendrin et al., 2005; Murchie et al., 2007; Murchie et al., in revision). In Ius Chasma, however, sulfates are found in thin floor units in enclosed depressions at the lowest elevations. Kieserite is at the lowest elevation, with polyhydrated sulfate and an unidentified hydrated phase, at higher elevations. Some poorly defined layering is visible on the HiRISE scale, but is not diagnostic. The total exposed thickness of kieserite is 300 m, with a total range in elevation of -4175 to -4475 m. The kieserite deposit is covered in places by pyroxene-bearing dunes. The polyhydrated sulfate outcrops range from -3515 to -4000 m. The unidentified hydrated phase outcrops between -3770 to -4100 m. The polyhydrated sulfate and unidentified hydrated material occur at the same elevations and do not have a clear stratigraphic relationship. Elsewhere in Ius Chasma, the unidentified hydrated material clearly drapes chasma floor units. The unidentified hydrated material is characterized by absorptions near 1.4 and 1.9 ?m, and a narrow doublet at 2.21 and 2.27 ?m. The deep ~1.9 ?m is due to the combination tone of the OH stretch and H2O bend and the ~1.4 ?m absorption is due to the 1st overtone of the OH stretch. Sulfates or other minerals with 2 or more water molecules per unit cell in their structure are necessary to account for deep water and hydroxyl absorptions in many spectra we observe. The doublet doesn't match any known sulfate, phyllosilicate, chloride, hydrated silica library spectra. Possibly a mixture of hydrated phases could explain this phase. The 2.21-2.26 ?m region is generally convex in sulfates, but gypsum (CaSO4 2H2O ) and jarosite group members (MFe3(SO4)2(OH)6) have absorptions there. However, neither sulfates' doublet matches the unidentified spectrum's minima. While there is no phyllosilicate that exactly matches the 2.21 and 2.27 ?m doublet, a combination of smectite clays, such as nontronite and montmorillonite, produces a similar doublet at 2.21 and 2.29 ?m. A third option that is spectrally close but not exact is hydrated silica. Hydrated silica has a wider absorption over 2.21- 2.25 ?m and its hydration bands are shifted to ~1.38 and ~1.91 ?m (Milliken et al., 2008). The location of kieserite in the lowest points of Ius Chasma, with polyhydrated sulfate exclusively found at higher elevations, suggests they were formed by nearly complete evaporation of a closed basin. Polyhydrated evaporites form first and then kieserite as the basin is drawn down. Originally, Ius Chasma may have been less connected to Melas Chasma than it is now (Peulvast and Masson, 1993). These sulfates may be evidence of an environment that supported isolated, evaporating basins. Better discrimination of the sulfate assemblages present and the stratigraphic relationships within the ILD is critical to understanding the environment during and since their formation.

Roach, L. H.; Mustard, J. F.; Murchie, S. L.; Milliken, R. E.; Crowley, J. K.; Bishop, J. L.; Arvidson, R. E.

2008-12-01

13

Hydrated minerals in the deposits of Aureum Chaos  

Science.gov (United States)

Hydrated minerals have been detected in many martian chaos regions and chasmata, playing a major role in its past aqueous activity. Based on short wave infrared data from CRISM, imagery and elevation data, we identified and mapped hydrated minerals in Aureum Chaos to shed light on their stratigraphy and geological context. The Interior Layered Deposits (ILDs) display three stratigraphic units: The lowest unit shows massive and also layered, high-albedo monohydrated sulfate (MHS, best matching kieserite; 20-650 m thick) with intercalated hydroxylated ferric sulfates (HFSs, best matching jarosite) and ferric oxides. The overlying polyhydrated sulfate (PHS) is commonly layered (20-40 m thick), smooth to heavily fractured, of lower albedo and partially contains ferric oxides. Spectrally neutral, distinctly layered, and bumpy cap rock (40-300 m thick) forms the top. We found spectral and morphological similarities to Aram Chaos (PHS, MHS, ferric oxides; texture of ILD and cap rock) and Juventae Chasma (HFS). Besides, the phyllosilicate nontronite was found attributed to chaotic terrain as light toned fractured exposure and within dark, smooth mantling. The coexistence of sulfates and phyllosilicates indicates changes in the geochemistry of the aqueous environment. Since sulfates and phyllosilicates could be alteration products, the observed mineralogy presumably is not the original; conversions between PHS and MHS, MHS or PHS into jarosite, jarosite into iron oxides are considered. Due to its occurrence along mantling edges and on flat surfaces of MHS without textural differences, it appears that PHS is an alteration product of MHS, e.g. due to surface exposure. The facies and relative timing of sulfate formation remains undefined. However, two different formation models are considered. The first implies contemporaneous ILD and PHS deposition and diagenetic sulfate conversion (into MHS, iron oxides) due to overburden later on. This model is less conclusive than groundwater evaporation -the second model- due to the lack of a sharp PHS-MHS boundary that would indicate a diagenetic formation. Alternatively, the second model suggests subsequent sulfate formation. Groundwater would have penetrated into pre-existing sulfate-free ILD. The permeability and porosity of ILD material would have defined the rate of water absorption and sulfate precipitation (low in cap rock?), resulting in cementation of probably aeolian deposited ILDs. We think this model is more consistent and could explain ILD stratigraphy with the potential anhydrous cap rock on top. The surface age of chaotic terrain (late Hesperian) and mantling deposits (mid to late Amazonian) limit the ILD age and possibly the emplacement of sulfates. Phyllosilicates in the mantling are presumably allochthonous. Limiting the timing of in situ phyllosilicates is more complicated; they could be Noachian (excavated material, following the phyllosian era), or instead syn- or post-chaotic. A close spatial and temporal association of sulfates and phyllosilicates, in which nontronite represents the deep facies, and sulfates the evaporitic facies is known from Earth and is also possible and would combine groundwater alteration with the observed mineralogy. The preservation of nontronite, HFS and MHS probably reflects a relatively dry environment with intermittent aqueous activity since their emplacement.

Sowe, M.; Wendt, L.; McGuire, P. C.; Neukum, G.

2012-03-01

14

Hydrated Iron Sulfate Minerals by FT-IR, ESEM and XRD: Effects of Hydration, Metal Ions, and Oxidative State  

Science.gov (United States)

Data from the Mars Exploration Rovers (MER) and orbital remote sensing have determined that iron-bearing sulfates and iron-sulfates account for much of the mineralogical variation on Martian chemical sediments. We have begun a comprehensive study to evaluate a suite of hydrated iron sulfate minerals at different levels of oxidation or mineral phases using micro-FT-IR, ESEM and XRD. Selected minerals include jarosite, copiapite, coquimbite, halotrichite, kornelite, melanterite, rhomboclase, roemerite, rozenite, and szomolnokite. The structure and wavelength of the water bands are controlled by the immediate proximity of the water molecules to the Fe3+ and Fe2+ cores. Iron and aluminum change the fundamental vibration amplitudes and shift the energy requirement for a specific bond vibration. The original mineral spectral signature can be present even after oxidative products form on the iron sulfate surfaces and basic spectral lines can be analyzed. When mineral samples were sectioned and analysis performed on the interior mineral surfaces, the spectra showed the predominant spectral lines under both conditions with most variations occurring in peak definition. ESEM-EDAX and XRD analysis confirmed the presence of oxidative products on the mineral surfaces even when the mineral samples were stored in anoxic conditions (under mineral oil) and refrigerated in airtight containers after sampling. Spectral variability between 30 micron spots within 200x200 micron areas showed minimal compositional / spectral variability. The micro-spectroscopic approach permits the study of complex iron sulfate mineral structures (e.g. evaporite sequences, crystal formations) to determine the hydration, metal ion, and oxidative state in terrestrial analog systems and on future Mars missions, without destruction of the sample.

Mielke, R.; Blaney, D.; Nordstrom, K.; Aplers, C.; Coleman, M.

2007-12-01

15

Diseases of uranium miners and other underground miners exposed to radon  

Energy Technology Data Exchange (ETDEWEB)

Excess lung cancer has been demonstrated in many groups of underground miners exposed to radon, including uranium miners and those mining other substances in radon-contaminated mines. In the United States, most underground uranium mines had shut down by the late 1980s, but occupational exposure to radon progeny remains a concern for many other types of underground miners and other underground workers. Worldwide, uranium mining continues, with documented production in Canada, South Africa and other African countries, and Australia. Thus, radon in underground mines remains a significant occupational hazard as the end of the twentieth century approaches.39 references.

Samet, J.M. (Department of Medicine, University of New Mexico, Albuquerque (Unites States))

1991-10-01

16

Respiratory infections in coal miners exposed to nitrogen oxides  

Energy Technology Data Exchange (ETDEWEB)

Coal miners working underground may be exposed chronically to low levels of nitric oxide and nitrogen dioxide from diesel engine emissions and from the use of explosives for blasting. The aims of this study were to establish whether long-term exposures to low concentrations of these gases at nine British coal mines had been associated with increased susceptibility to respiratory infections, and if so, to estimate relative risks for different levels of exposure. The overall conclusion of this study is that exposures to the levels of nitrogen oxides that were found at the nine British coal mines do not detectably increase the chances that miners will absent themselves from work because of chest infections. 45 refs., 32 figs., 25 tabs.

Jacobsen, M.; Smith, T.A.; Hurley, J.F.; Robertson, A.; Roscrow, R.

1987-01-01

17

Microbeam recoil detection for hydration of minerals studies  

International Nuclear Information System (INIS)

[en] 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 (

1993-01-01

18

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

19

Immunomodulatory effects of mineral fibres in occupationally exposed workers.  

UK PubMed Central (United Kingdom)

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.

Tulinska J; Jahnova E; Dusinska M; Kuricova M; Liskova A; Ilavska S; Horvathova M; Wsolova L; Kyrtopoulos SA; Collins A; Harrington V; Fuortes L

2004-09-01

20

Microbeam recoil detection for hydration of minerals studies  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-12-31

 
 
 
 
21

Respiratory infections in coal miners exposed to nitrogen oxides.  

UK PubMed Central (United Kingdom)

Coal miners working underground may be exposed chronically to low levels of nitric oxide and nitrogen dioxide from diesel engine emissions and from the use of explosives for blasting. The aims of this study were to establish whether long-term exposures to low concentrations of these gases at nine British coal mines had been associated with increased susceptibility to respiratory infections and, if so, to estimate the relative risks for different levels of exposure. The nine mines concerned had been involved, since 1954, in a prospective epidemiological study of coal miners' health. Median levels of nitrogen oxides in 4,933 pairs of full-shift samples, taken at the mines during the years 1976 through 1982 were 0.2 ppm nitric oxide and 0.03 ppm nitrogen dioxide; 10 percent of the concentrations exceeded 1.1 ppm nitric oxide and 0.08 ppm nitrogen dioxide. Multiple regression estimates of concentrations associated with different underground locations, types of work, and mining conditions at each mine were combined with detailed records of miners' attendance at work at similar locations in earlier years. These retrospective estimates of individuals' underground exposures to nitrogen oxides referred to between five- and 16-year periods of exposure. Also available for study were records of the men's exposures to respirable mine dusts and information from five-yearly medical surveys about their smoking habits, respiratory symptoms, and questionnaire-elicited reports of sickness absences attributed, among other things, to respiratory infections. The reliability of the latter reports was examined in a sample of 471 of the men by comparing the answers to the questionnaire with physicians' diagnoses on certified sickness absence records. Miners' references to bronchitis, influenza, or colds as the cause of prolonged sickness absence during the three years preceding the surveys did, in general, reflect real spells of absence from work, lasting at least seven days, that had been diagnosed by doctors as due to respiratory infections. But only about 20 percent of the men whose colliery records indicated that there had been such an absence acknowledged them in the survey as due to a "chest illness". Most of the under-reporting was of absence certified as due to influenza, colds, or "upper respiratory tract infection", and this under-reporting was not related to the men's ages or smoking habits. The main analyses referred to 5,408 reports of colds, influenza, or bronchitis at a total of 40,071 interviews involving nearly 20,000 miners.(ABSTRACT TRUNCATED AT 400 WORDS)

Jacobsen M; Smith TA; Hurley JF; Robertson A; Roscrow R

1988-07-01

22

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

Energy Technology Data Exchange (ETDEWEB)

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.

Smith, David E.

2000-09-14

23

Supplementation of Acqua Lete® (Bicarbonate Calcic Mineral Water) improves hydration status in athletes after short term anaerobic exercise.  

UK PubMed Central (United Kingdom)

BACKGROUND: Experimental studies suggest that mineral waters with high concentrations of calcium and bicarbonate can impact acid-base balance. The purpose of this study was to test the effect on acid-base balance and specific urine gravity, of a bicarbonate calcic mineral water (Acqua Lete®) compared to a minimally mineralized water. METHODS: 88 amateur male athletes underwent two experimental trials with a modified Wingate test: the first was carried out without hydration (Control Test, Test C, n = 88); the second was carried out after one week of controlled hydration (Test with hydration, Test H, n = 88), with 1.5 L/day of a very low mineral content water (Group A, n = 44) or 1.5 L/day of Acqua Lete® (Group B, n = 44). Measure of body temperature, bioimpedance analysis, muscular ultrasound, and urinalysis were taken before (t0), immediately after (t1), 5' (t2), and 30' (t3) after exercise. RESULTS: Hydration results in a decreased core temperature; muscular ultrasound showed increased muscle thickness after exercise related to content of body water. Regarding urinalysis, in test H, we found in both groups after exercise a significant decrease of specific urine gravity with significantly lower levels in Group B. We also found a significant increase of pH in the same Group B. CONCLUSIONS: In conclusion all the athletes hydrated with Acqua Lete® showed a positive impact on hydration status after anaerobic exercise with significant decrease of specific urine gravity and a positive effect on pH.

Brancaccio P; Limongelli FM; Paolillo I; D'Aponte A; Donnarumma V; Rastrelli L

2012-01-01

24

Occurrence and Stratigraphy of Phyllosilicate and Hydrated Silicate Minerals on Mars from OMEGA and CRISM  

Science.gov (United States)

The OMEGA investigation on the Mars Express spacecraft identified phyllosilicates across a range of martian geologic terrains, but importantly the mineral occurrences were largely confined to Noachian-aged terrains. This led to the new paradigm that that an active hydrologic system was restricted to early Mars history. The order of magnitude increase in spatial resolution of the CRISM instrument on Mars Reconnaissance Orbiter over OMEGA is used here to assess mineralogic diversity and stratigraphic relationships in several phyllosilicate regions. CRISM data show definitive evidence for diagnostic Al-OH and Fe/Mg-OH absorptions of phyllosilicate minerals, similar to those seen by OMEGA, but reveal mineralogic diversity down to the fine spatial resolution of the instrument. Al-OH phyllosilicates have been confirmed in Mawrth Vallis and are identified for the first time in the Nili Fossae region, displaying spectra consistent with kaolinite, illite and/or muscovite. A diversity of Fe/Mg-OH phyllosilicates is observed; smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. A new spectral class of mineral is found interpreted to be hydrated volcanic or impact glass. This material is found in isolated regions in the Noachian highlands. Fe/Mg phyllosilicate and hydrated glasses are found in rims, ejecta, and central peaks of craters in the southern highland Noachian cratered terrain indicating excavation of altered crust from depth. Phyllosilicate is also found in deposits clearly laid by water in Jezero, Ritchy, and Holden crater. Stratigraphic relationships in the many regions show unaltered volcanic or igneous lithologies overlying phyllosilicate-bearing rocks indicating an abrupt cessation of widespread alteration in the late Noachian. The predominance of smectite clay signatures implies moderate to low temperatures of formation (<200°C) such as might have existed in the near surface or shallow crust. The formation of phyllosilicate and hydrated glass could have been a consequence of near surface weathering or low temperature hydrothermal processes in a cooling crust

Mustard, J. F.; Murchie, S. L.; Pelkey, S. M.; Ehlmann, B. L.; Milliken, R. E.; Grant, J. A.; Bibring, J.; Poulet, F.; Bishop, J. L.; Roach, L. E.; Seelos, F.; Arvidson, R. E.; Swayze, G.; Clark, R.; Wiseman, S.; Humm, D.

2007-12-01

25

[The adaptive capacities of the cardiovascular system in miners exposed to vibration].  

UK PubMed Central (United Kingdom)

Diagnostics criteria for work-related adaptation disorders in respect of cardiovascular system factors have been developed; the stages of disadaptation have been characterized through the example of vibration exposed miners working under the conditions of cool microclimate.

Konevskikh LA; Oranski? IE; Makogon IS

2013-01-01

26

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

2010-01-01

27

Supplementation of Acqua Lete® (Bicarbonate Calcic Mineral Water) improves hydration status in athletes after short term anaerobic exercise  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Experimental studies suggest that mineral waters with high concentrations of calcium and bicarbonate can impact acid–base balance. The purpose of this study was to test the effect on acid–base balance and specific urine gravity, of a bicarbonate calcic mineral water (Acqua Lete®) compared to a minimally mineralized water. Methods 88 amateur male athletes underwent two experimental trials with a modified Wingate test: the first was carried out without hydration (Control Test, Test C, n = 88); the second was carried out after one week of controlled hydration (Test with hydration, Test H, n = 88), with 1.5 L/day of a very low mineral content water (Group A, n = 44) or 1.5 L/day of Acqua Lete® (Group B, n = 44). Measure of body temperature, bioimpedance analysis, muscular ultrasound, and urinalysis were taken before (t0), immediately after (t1), 5’ (t2), and 30’ (t3) after exercise. Results Hydration results in a decreased core temperature; muscular ultrasound showed increased muscle thickness after exercise related to content of body water. Regarding urinalysis, in test H, we found in both groups after exercise a significant decrease of specific urine gravity with significantly lower levels in Group B. We also found a significant increase of pH in the same Group B. Conclusions In conclusion all the athletes hydrated with Acqua Lete® showed a positive impact on hydration status after anaerobic exercise with significant decrease of specific urine gravity and a positive effect on pH.

Brancaccio Paola; Limongelli Francesco; Paolillo Iride; D’Aponte Antonio; Donnarumma Vincenzo; Rastrelli Luca

2012-01-01

28

Heterogeneous ice nucleation of mineral dust particles exposed to ozone  

Science.gov (United States)

Deposition and immersion mode ice nucleation studies of kaolinite (Ka) and Arizona Test Dust (ATD) particles exposed to ozone at 430 ppbv, 1.4 and 4.3 ppmv for approximately 2 hours in a stainless steel aerosol tank are presented. The polydisperse particles used have a mode mobility diameter of 800 nm for Ka and 400 nm for ATD. The portable ice nucleation chamber (PINC) and immersion chamber (IMCA-ZINC) were used to study deposition and immersion mode ice nucleation respectively. Both instruments sampled through a particle impactor with a diameter cut-off size of 1 ?m. Preliminary results indicate that ice nucleation can be enhanced or inhibited depending on ozone concentration used for the ageing process with higher concentrations suppressing ice nucleation in both immersion and deposition modes. Additionally, Ka and ATD respond differently to the ageing process and to the different modes of ice nucleation. Ozone surface coverage and initial uptake coefficients are presented for the low exposure studies to explain the ice nucleation behavior observed. Ice Active Surface Site Densities (IASSD) are presented as a means of comparison and parameterization of the data to predict potential atmospheric ice nuclei (IN) concentrations.

Kanji, Zamin A.; Welti, André; Chou, Cédric; Stetzer, Olaf; Lohmann, Ulrike

2013-05-01

29

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument  

Science.gov (United States)

Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

Mustard, John F.; Murchie, S. L.; Pelkey, S. M.; Ehlmann, B. L.; Milliken, R. E.; Grant, J. A.; Bibring, J.-P.; Poulet, F.; Bishop, J.; Dobrea, E. Noe; Roach, L.; Seelos, F.; Arvidson, R. E.; Wiseman, S.; Green, R.; Hash, C.; Humm, D.; Malaret, E.; McGovern, J. A.; Seelos, K.; Clancy, T.; Clark, R.; Marais, D. D.; Izenberg, N.; Knudson, A.; Langevin, Y.; Martin, T.; McGuire, P.; Morris, R.; Robinson, M.; Roush, T.; Smith, M.; Swayze, G.; Taylor, H.; Titus, T.; Wolff, M.

2008-07-01

30

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument.  

UK PubMed Central (United Kingdom)

Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

Mustard JF; Murchie SL; Pelkey SM; Ehlmann BL; Milliken RE; Grant JA; Bibring JP; Poulet F; Bishop J; Dobrea EN; Roach L; Seelos F; Arvidson RE; Wiseman S; Green R; Hash C; Humm D; Malaret E; McGovern JA; Seelos K; Clancy T; Clark R; Marais DD; Izenberg N; Knudson A; Langevin Y; Martin T; McGuire P; Morris R; Robinson M; Roush T; Smith M; Swayze G; Taylor H; Titus T; Wolff M

2008-07-01

31

The stability of sulfate and hydrated sulfate minerals near ambient conditions and their significance in environmental and planetary sciences  

Science.gov (United States)

Sulfate and hydrated sulfate minerals are abundant and ubiquitous on the surface of the Earth and also on other planets and their satellites. The humidity-buffer technique has been applied to study the stability of some of these minerals at 0.1 MPa in terms of temperature-relative humidity space on the basis of hydration-dehydration reversal experiments. Updated phase relations in the binary system MgSO4-H2O are presented, as an example, to show how reliable thermodynamic data for these minerals could be obtained based on these experimental results and thermodynamic principles. This approach has been applied to sulfate and hydrated sulfate minerals of other metals, including Fe (both ferrous and ferric), Zn, Ni, Co, Cd, and Cu.Metal-sulfate salts play important roles in the cycling of metals and sulfate in terrestrial systems, and the number of phases extends well beyond the simple sulfate salts that have thus far been investigated experimentally. The oxidation of sulfide minerals, particularly pyrite, is a common process that initiates the formation of efflorescent metal-sulfate minerals. Also, the overall abundance of iron-bearing sulfate salts in nature reflects the fact that the weathering of pyrite or pyrrhotite is the ultimate source for many of these phases. Many aspects of their environmental significance are reviewed, particularly in acute effects to aquatic ecosystems related to the dissolution of sulfate salts during rain storms or snow-melt events.Hydrous Mg, Ca, and Fe sulfates were identified on Mars, with wide distribution and very large quantities at many locations, on the basis of spectroscopic observations from orbital remote sensing and surface explorations by rovers. However, many of these findings do not reveal the detailed information on the degree of hydration that is essential for rigorous interpretation of the hydrologic history of Mars. Laboratory experiments on stability fields, reactions pathways, and reaction rates of hydrous sulfates likely to be found on Mars enhance our understanding of the degrees of hydration of various sulfates that should currently exist on Mars at various seasons and locations and during various atmospheric pressure and obliquity periods. Two sets of systematic experiments were described; one on hydrous Mg sulfates and the other on hydrous Fe3+ sulfates. Also, their implications to Mars sulfates mineralogy were discussed.

Chou, I.-Ming; Seal, Robert R.; Wang, Alian

2013-01-01

32

The risk of hospitalisation for infectious pneumonia in mineral dust exposed industries.  

UK PubMed Central (United Kingdom)

OBJECTIVES: The purpose of the study was to elucidate the relationship between industries characterised by mineral dust exposure and infectious pneumonia. METHODS: The authors applied a retrospective record linkage design and used the nationwide specific health examination database and identified industries where mineral dust exposure occurs and a control group composed of workers who had been exposed to noise-only during a 2000-2004 period. The database was matched with National Health Insurance claim records to identify pneumonia admissions from 2000 to 2005. The indirectly standardised admission ratios (SARs) for pneumonia admissions were estimated by comparing mineral dust exposed industry workers with noise-only exposed workers. RESULTS: The authors found significantly elevated SARs in both men (1.54, 95% CI 1.13 to 2.05) and women (3.23, 95% CI 1.40 to 6.37) working in the cement, lime, plaster and plaster products industries, and only in men working in the cast-metals industry (foundry) (1.64, 95% CI 1.25 to 2.11). CONCLUSIONS: These results support the association between mineral dust exposure, as well as metal fumes, and infectious pneumonia.

Koh DH; Moon KT; Kim JY; Choe SW

2011-02-01

33

Multiphasic finite element modeling of concrete hydration  

International Nuclear Information System (INIS)

This paper presents a model predicting the development of hydration and its consequences on temperature and water content. As it considers the effects of climatic conditions, the proposed model is a promising tool to evaluate the temperature, hydric and hydration fields of structures in situ. The hydration model predicts the hydration evolution of several main species (not only clinker but also mineral additions like fly ash or silica fume for instance). For each component, the modeling considers hydration development and chemical interaction between reactions. It also takes into account temperature and water content effects on reaction kinetics through thermal and hydric activation. Hydration development in turn modifies the thermal and hydric states of material. The result is a numerical model coupling hydration, and the thermal and hydric states of cement-based material. The model was tested on a 27 m3 concrete block in situ equipped with temperature sensors situated in the core and close to the face exposed to solar radiation.

2007-01-01

34

The mortality experience of a group of Newfoundland fluorspar miners exposed to Rn progeny  

International Nuclear Information System (INIS)

A cohort study of the mortality experience (1950-1984) of 1,772 Newfoundland fluorspar miners occupationally exposed to high levels of radon daughters has been conducted using two control groups (surface workers and Newfoundland males). Observed numbers of cancers of the lung, salivary gland and buccal cavity/pharynx were significantly elevated among underground miners. A highly significant relationship was noted between radon daughter exposure and risk of dying of lung cancer; the small numbers of salivary gland (n = 2) and buccal cavity/pharynx cancers (n = 6) precluded meaningful analysis of dose-response. Also significantly elevated among underground miners were deaths from silicosis and pneumoconioses. No statistically significant excess was found for any cause of death among surface workers. Using external controls, attributable and relative risk coefficients for lung cancer were estimated as 6.3 per working level month per million person-years and 0.89 percent per working level month respectively. Attributable risk coefficients were similar to some, but not all related mining studies. Relative risk coefficients were highest for those first exposed attributable risks to non-smokers. Relative risks fell sharply with age at observation whereas attributable risks were lowest in the youngest and oldest age groups. Using the risk coefficients from the present study, a miner exposed for 30 years at 4 WLM per year from age 20 has a risk of 7,366 per 100,000 of dying of lung cancer by age 70 using the relative risk model and a risk of 6,371 per 100,000 using the attributable risk model. This compares to 3,740 per 100,000 for a non-exposed male. 85 refs.

1988-01-01

35

Hydration state of zeolites, clays, and hydrated salts under present-day martian surface conditions: Can hydrous minerals account for Mars Odyssey observations of near-equatorial water-equivalent hydrogen?  

Science.gov (United States)

Thermodynamic data for several clays, zeolites, and MgSO4 salts were combined with calculated yearly mean temperatures and water-vapor pressures on the martian surface to predict mineral hydration states from low to middle latitudes. These predictions were used to evaluate whether the necessary amount and distribution of hydrous minerals were compatible with the Mars Odyssey observations of water-equivalent hydrogen (WEH). Our results indicate that zeolites like chabazite or clay minerals like Ca-montmorillonite would have to be unrealistically abundant in the martian soil (as much as 55 wt%) while Mg-sulfate hydrates at concentrations between 2 and 11 wt% could account for the WEH. However, the geographic distribution of WEH is incompatible with a uniformly distributed mineralogy in equilibrium with the annual mean P T environment. A heterogeneous distribution of a mixture of different hydrous minerals, reflecting a heterogeneous Mars surface geology, may better explain a significant portion of the observed near-equatorial WEH.

Fialips, Claire I.; Carey, J. William; Vaniman, David T.; Bish, David L.; Feldman, William C.; Mellon, Michael T.

2005-11-01

36

Porphyrin metabolism in lymphocytes of miners exposed to diesel exhaust at oil shale mine.  

Science.gov (United States)

The present study was carried out on the evaluation and application of new biomarkers for populations exposed to occupational diesel exhaust at oil shale mines. Since not only genotoxic effects may play an important role in the generation of tumors, the level of porphyrin metabolism was proposed as a biomarker of diesel exhaust exposure effects. The data on determination of 5-aminolevulinic acid (ALA) synthesis and heme formation in lymphocytes from groups of 50 miners exposed to diesel exhaust and 50 unexposed surface workers of oil shale mine are presented. All workers were examined and interviewed using structured questionnaires. The levels of benzene, carbon monoxide and nitric oxides in air as well as concentrations of 1-nitropyrene and elemental carbon in particulate matter were used for evaluation of exposure to diesel exhaust in mine. The levels of ALA and protoporphyrin (PP), activities of ALA synthetase (ALA-S) and ferrochelatase (FC), as well as levels of PP associated with DNA (PP/DNA) were investigated in lymphocytes spectrophotometrically. Significant differences in activity of ALA synthesis and heme formation between exposed miners and surface workers were found (207+/-23 vs. 166+/-14 pmol/10(6) lymp./30' for ALA-S and 46.1+/-3.8 vs. 54.8+/-4.1 pmol/10(6) lymp./60' for FC activities, respectively, P<0.001). ALA-S activity was higher and ALA accumulated in lymphocytes of exposed miners. Inhibition of FC activity caused PP cellular accumulation and an increase in the PP/DNA level (P<0.05). Tobacco smoking led to the increase of ALA biosynthesis in lymphocytes of both surface and underground smokers. The comparison of data obtained for non-smokers and smokers of both groups of workers has shown a significant difference (P<0.05). The work duration of underground or surface workers did not significantly influence the investigated biochemical parameters. The determination of ALA synthesis in lymphocytes could be a useful biomonitoring index of organism sensitivity to underground working. The alterations of PP levels, FC activity and PP/DNA association in peripheral lymphocytes of miners illustrate the harmful effects of exposure to diesel exhaust. PMID:15081736

Muzyka, V; Scheepers, P T J; Bogovski, S; Lang, I; Schmidt, N; Ryazanov, V; Veidebaum, T

2004-04-25

37

Porphyrin metabolism in lymphocytes of miners exposed to diesel exhaust at oil shale mine  

Energy Technology Data Exchange (ETDEWEB)

The present study was carried out on the evaluation and application of new biomarkers for populations exposed to occupational diesel exhaust at oil shale mines. Since not only genotoxic effects may play an important role in the generation of tumors, the level of porphyrin metabolism was proposed as a biomarker of diesel exhaust exposure effects. The data on determination of 5-aminolevulinic acid (ALA) synthesis and heme formation in lymphocytes from groups of 50 miners exposed to diesel exhaust and 50 unexposed surface workers of oil shale mine are presented. All workers were examined and interviewed using structured questionnaires. The levels of benzene, carbon monoxide and nitric oxides in air as well as concentrations of 1-nitropyrene and elemental carbon in particulate matter were used for evaluation of exposure to diesel exhaust in mine. The levels of ALA and protoporphyrin (PP), activities of ALA synthetase (ALA-S) and ferrochelatase (FC), as well as levels of PP associated with DNA (PP/DNA) were investigated in lymphocytes spectrophotometrically. Significant differences in activity of ALA synthesis and heme formation between exposed miners and surface workers were found (207{+-}23 vs. 166{+-}14 pmol/10{sup 6} lymp./30' for ALA-S and 46.1{+-}3.8 vs. 54.8{+-}4.1 pmol/10{sup 6} lymp./60' for FC activities, respectively, P<0.001). ALA-S activity was higher and ALA accumulated in lymphocytes of exposed miners. Inhibition of FC activity caused PP cellular accumulation and an increase in the PP/DNA level (P<0.05). Tobacco smoking led to the increase of ALA biosynthesis in lymphocytes of both surface and underground smokers. The comparison of data obtained for non-smokers and smokers of both groups of workers has shown a significant difference (P<0.05). The work duration of underground or surface workers did not significantly influence the investigated biochemical parameters. The determination of ALA synthesis in lymphocytes could be a useful biomonitoring index of organism sensitivity to underground working. The alterations of PP levels, FC activity and PP/DNA association in peripheral lymphocytes of miners illustrate the harmful effects of exposure to diesel exhaust.

Muzyka, V.; Bogovski, S.; Lang, I.; Schmidt, N.; Ryazanov, V.; Veidebaum, T. [Laboratory of Environmental Carcinogens, Institute of Experimental and Clinical Medicine, Hiiu 42, Tallinn 11619 (Estonia); Scheepers, P.T.J. [Department of Epidemiology and Biostatistics, University Medical Centre St Radboud, P.O. Box 9101, Nijmegen NL 6500 HB (Netherlands)

2004-04-25

38

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

International Nuclear Information System (INIS)

[en] 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

2009-01-01

39

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

Energy Technology Data Exchange (ETDEWEB)

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 {mu}g L{sup -1}n = 137; Iberian Peninsula range: 5.60-217.30 {mu}g L{sup -1}n = 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.

Gangoso, Laura [Department of Conservation Biology, Estacion Biologica de Donana, C.S.I.C., Avda Ma Luisa s/n, 41013 Sevilla (Spain)], E-mail: laurag@ebd.csic.es; Alvarez-Lloret, Pedro [Department of Mineralogy and Petrology, University of Granada, Avda Fuentenueva s/n, 18002 Granada (Spain)], E-mail: pedalv@ugr.es; Rodriguez-Navarro, Alejandro A.B. [Department of Mineralogy and Petrology, University of Granada, Avda Fuentenueva s/n, 18002 Granada (Spain)], E-mail: anava@ugr.es; Mateo, Rafael [Instituto de Investigacion en Recursos Cinegeticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo s/n, 13071 Ciudad Real (Spain)], E-mail: Rafael.Mateo@uclm.es; Hiraldo, Fernando [Department of Conservation Biology, Estacion Biologica de Donana, C.S.I.C., Avda Ma Luisa s/n, 41013 Sevilla (Spain)], E-mail: hiraldo@ebd.csic.es; Donazar, Jose Antonio [Department of Conservation Biology, Estacion Biologica de Donana, C.S.I.C., Avda Ma Luisa s/n, 41013 Sevilla (Spain)], E-mail: donazar@ebd.csic.es

2009-02-15

40

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

Directory of Open Access Journals (Sweden)

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

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

2011-01-01

 
 
 
 
41

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

International Nuclear Information System (INIS)

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

1984-01-01

42

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

International Nuclear Information System (INIS)

[en] 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

2005-01-01

43

Corrosion textures of simulated nuclear waste glass and nuclear waste slag when exposed to water vapor hydration at 200 C  

International Nuclear Information System (INIS)

[en] A Savannah River Laboratory nuclear waste glass (SRL) and a plasma furnace nuclear waste slag were subjected to vapor hydration as small suspended rectangular samples within a sealed reaction bomb at 200 C for time periods of up to 26 days. The samples were then removed from the reaction bomb and the residual water analyzed by ICP and ICP-MS for trace elements and bulk glass constituents. The sample hydration rind thickness was measured and photographed with an optical microscope and the data plotted as thickness vs. time profiles which are presented as an indicator of the relative durability of the waste medium. The chemical transport of various dissolved glass constituents from the bulk medium to the sample surface developed residual diffusion textures within the hydration rind which have been investigated relative to the residual bomb water chemistry and SEM-EDX analysis of the hydration rind. These textures reveal that the water vapor diffuses into the surface of the nuclear waste slag along the path of least resistance and selectively dissolves the more soluble constituents within the slag. The development of secondary silicate phases and selective dissolution of soluble elements contribute to extensive fracturing of the hydrated region

1994-01-01

44

Pulmonary fibrosis in workers exposed to non-asbestiform tremolite asbestos minerals.  

UK PubMed Central (United Kingdom)

BACKGROUND: Studies of the health effects of non-asbestiform asbestos minerals remain inconclusive. Nephrite is a type of non-asbestiform tremolite mineral. We assessed the risk for pulmonary fibrosis in workers who process nephrite. METHODS: A cross-sectional study that included 344 stone workers and their families was undertaken in Taiwan in 2010. The diagnostic criteria for pulmonary fibrosis included (1) radiographic fibrosis profusion of 1/1 or greater and (2) audible lung crackles confirmed by physician. The nephrite samples were analyzed using polarized light and transmission electron microscopy combined with selected-area electron diffraction and energy-dispersive x-ray spectroscopy. RESULTS: After excluding 16 subjects with histories of tuberculosis or previous employment in metal casting and welding, as well as 23 family members who had not worked in the stone industry, we analyzed 305 subjects. Processing nephrite increased the risk for pulmonary fibrosis (odds ratio = 2.8 [95% confidence interval = 1.0-9.9] and unchanged after adjustment for age and smoking). Bulk sample analyses showed that the nephrite is a tremolite mineral composed of both asbestiform and non-asbestiform components. The cat's-eye nephrite had the highest asbestiform fibrous content, and the average length and aspect ratio of elongated mineral particles were the highest of all the nephrite types. Compared with workers processing other types of nephrite, workers processing cat's-eye nephrite had the highest risk for pulmonary fibrosis. CONCLUSION: Processing non-asbestiform tremolite mineral may increase the risk for pulmonary fibrosis. Medical monitoring is warranted for workers with such exposure.

Yang HY; Shie RH; Chen PC

2013-01-01

45

Alternation in mineral accumulation pattern of Triticum aestivum L. exposed to particulate pollution  

Energy Technology Data Exchange (ETDEWEB)

Air pollutants influence the pattern of mineral accumulation in plants. In this experiment, wheat plants were grown in 1 m/sup 2/ plots and treated with the same amount of cement dust at pre-flowering, flowering, and post-flowering stages, separately. The plants were sampled periodically and analyzed for N, P, K and Ca concentrations. The observations revealed that under the influence of cement-dust pollution, the accumulation of N and P in plants declined, whereas that of K and Ca was enhanced. It was also noted that changes in mineral accumulation were more pronounced in plants subjected to cement dust at flowering stage than at pre- and post-flowering stages.

Singh, S.N.

1983-01-01

46

Bone mineral density in adolescents with eating disorders exposed to selective serotonin reuptake inhibitors.  

UK PubMed Central (United Kingdom)

Retrospective chart review was used to collect data from adolescents seen in a specialized eating disorder program over an 11-year period in order to investigate any association between exposure to selective serotonin reuptake inhibitors (SSRIs) and bone mineral density (BMD). SSRI users were matched with controls based on age (within 1.5 years), gender, eating disorder diagnosis, and percent ideal body weight (within 5%), resulting in a sample of 31 pairs. SSRI users had significantly lower BMD z-scores, compared to controls (-1.094 vs. -0.516, p < .035), suggesting that exposure to SSRIs may be a risk factor for lowered BMD.

Couturier J; Sy A; Johnson N; Findlay S

2013-01-01

47

A review of studies of mortality among miners exposed to radon daughters  

International Nuclear Information System (INIS)

The maximum permissible limit for exposure to radon daughters in Australian uranium mines is 4 Working level months per year. This limit is based on studies of lung cancer among US uranium miners which showed no statistically significant excess incidence of this disease in workers who had a cumulative exposure of less than 120 WLM. More recently published Swedish, Canadian and Czech studies provide higher risk per unit exposure factors than the US studies. The Czech studies show no statistically significant excess incidence of lung cancer below a cumulative exposure of 100 WLM, but the Swedish and Canadian studies suggest that observable increases in lung cancer frequency may in fact occur at low cumulative exposures. All of the studies are open to criticism. The methodology used in the US studies tended to underestimate the number of deaths in the group of miners with low cumulative exposures and to overstate the expected (background) rate of lung cancer development. The other published studies are also subject to errors because of lack of suitable control populations, information regarding previous or subsequent work experience, medical and smoking histories and analyses of deaths from other causes.

1983-01-01

48

Review of studies of mortality among miners exposed to radon daughters  

Energy Technology Data Exchange (ETDEWEB)

The maximum permissible limit for exposure to radon daughters in Australian uranium mines is 4 Working level months per year. This limit is based on studies of lung cancer among US uranium miners which showed no statistically significant excess incidence of this disease in workers who had a cumulative exposure of less than 120 WLM. More recently published Swedish, Canadian and Czech studies provide higher risk per unit exposure factors than the US studies. The Czech studies show no statistically significant excess incidence of lung cancer below a cumulative exposure of 100 WLM, but the Swedish and Canadian studies suggest that observable increases in lung cancer frequency may in fact occur at low cumulative exposures. All of the studies are open to criticism. The methodology used in the US studies tended to underestimate the number of deaths in the group of miners with low cumulative exposures and to overstate the expected (background) rate of lung cancer development. The other published studies are also subject to errors because of lack of suitable control populations, information regarding previous or subsequent work experience, medical and smoking histories and analyses of deaths from other causes.

Collins, C. (Australian Atomic Energy Commission, Mascot)

1983-07-01

49

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

Energy Technology Data Exchange (ETDEWEB)

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

Cruz-Zaragoza, E.; Roman-Lopez, J.; Cruz, L. Perez; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Chiaravalle, E.; Mangiacotti, M.; Marchesani, G. [Centro di Referenza Nazionale per la Ricerca della Radioattivita nel Settore Zootecnico-Veterinario, Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, I-71121 Foggia (Italy)

2013-07-03

50

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

Science.gov (United States)

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

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

2013-04-01

51

Minerals  

Directory of Open Access Journals (Sweden)

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

Vaquero, M. P.

1998-01-01

52

Methane hydrate; Methane hydrate  

Energy Technology Data Exchange (ETDEWEB)

This paper introduces the results of studies on natural gas hydrate presented at the 10th lecture meeting for studies at the Geological Survey of Japan. The natural gas hydrate is a sherbet-like material composed of such a gas as methane entrapped in an icy material. The hydrate is distributed widely over frozen soil area in the Arctic Zone and continental slopes in oceans. It is believed distributed also in sea areas surrounding Japan. This material is expected as a new energy resource for the 21st century. This paper describes studies to elucidate a bottom simulating reflector (BSR) having close relation with methane hydrate as a cross section which records sound wave exploration results, and physico-chemical properties of natural gas hydrate using indoor synthesis experiments. Studies are also being done on composition and stability of gas hydrate in a mixed condition with gases other than methane, and on estimation of methane hydrate property values using computer simulations. With respect to exploration and mining of the resources, the paper introduces sampling and analyses of specimens, and the current status of drilling and development at permanently frozen soil areas, supported by an international deep-sea drilling plan. 103 refs., 65 figs., 5 tabs.

NONE

1997-02-01

53

Ruminant Mineral Feed Additive  

UK PubMed Central (United Kingdom)

A ruminant mineral feed additive for dairy cattle and ruminant animals includes a unique combination of zeolite and dolomitic hydrate mineral fines that are prilled and hydrothermally reacted to produce a valuable dietary supplement for control of acidosis.

PETERSON STEPHEN L

54

RUMINANT MINERAL FEED ADDITIVE  

UK PubMed Central (United Kingdom)

A ruminant mineral feed additive for dairy cattle and ruminant animals includes a unique combination of zeolite and dolomitic hydrate mineral fines that are prilled and hydrothermally reacted to produce a valuable dietary supplement for control of acidosis.

PETERSON STEPHEN L

55

Factors that influence the formation and stability of hydrated ferrous sulfate in coal dusts. Possible relation to the emphysema of coal miners  

Energy Technology Data Exchange (ETDEWEB)

Epidemiological studies have shown that a causal relationship may exist between coal dust exposure and emphysema in coal miners. Emphysema can be considered as one of the human pathologies associated with oxidative stress, resulting from oxidant-induced {alpha}{sub 1}-antitrypsin ({alpha}{sub 1}-AT) inactivation and uncontrolled proteolysis of lung tissue. We have previously reported that certain coal dusts contained hydrated ferrous sulfate (FeSO{sub 4}) that inactivated {alpha}{sub 1}-AT. In the present study, we have shown that the FeSO{sub 4} originated from oxidation of pyrite (FeS{sub 2}), which is a typical contaminant of coal dusts. The relative humidity and microenvironmental around individual pyrite particles influence the formation of FeSO{sub 4} in the coal. However, the subsequent human exposure to coal dust containing FeSO{sub 4} depends on the stability of the formed FeSO{sub 4}. We found that pH played the most important role in stabilizing the FeSO{sub 4}, such that a final pH < 4.5 after oxidation of pyrite stabilized FeSO{sub 4}, whereas at high pH the conversion of reactive Fe{sup 2+} to Fe{sup 3+} was immediate. Sulfuric acid (H{sub 2}SO{sub 4}), which is also produced by the oxidation of pyrite, can lower the pH, but it can also be neutralized by other minerals in coal dusts, such as calcite (CaCO{sub 3}). The stability of FeSO{sub 4} in coal dust can also be influenced by the length of exposure to air. Our studies demonstrated that coal samples differed in their capacity to stabilize FeSO{sub 4}. This current study strengthens our previous reported hypothesis that emphysema, which occurs irregularly in coal miners, could be directly related to exposure to coal dust containing FeSO{sub 4}. 35 refs., 3 figs., 4 tabs.

Huang, Xi; Zalma, R.; Pezerat, H. [Universite P. et M. Curie, Paris (France)

1994-05-01

56

Mineralogy of Juventae Chasma: Sulfates in the light-toned mounds, mafic minerals in the bedrock, and hydrated silica and hydroxylated ferric sulfate on the plateau  

Science.gov (United States)

Juventae Chasma contains four light-toned sulfate-bearing mounds (denoted here as A-D from west to east) inside the trough, mafic outcrops at the base of the mounds and in the wall rock, and light-toned layered deposits of opal and ferric sulfates on the plateau. Hyperspectral visible/near-infrared Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra were used to identify monohydrated and polyhydrated sulfate (PHS) outcrops of layered material on the bright mounds. Most of the monohydrated sulfate signatures closely resemble those of szomolnokite (FeSO4·H2O), characterized by a water band near 2.08 ?m, while some areas exhibit spectral features more similar to those of kieserite (MgSO4·H2O), with a band centered closer to 2.13 ?m. The largest PHS outcrops occur on the top of mound B, and their spectral features are most consistent with ferricopiapite, melanterite, and starkeyite, but a specific mineral cannot be uniquely identified at this time. Coordinated analyses of CRISM maps, Mars Orbiter Laser Altimeter elevations, and High Resolution Imaging Science Experiment images suggest that mounds A and B may have formed together and then eroded into separate mounds, while mounds C and D likely formed separately. Mafic minerals (low-Ca pyroxene, high-Ca pyroxene, and olivine) are observed in large ˜2-10 km wide outcrops in the wall rock and in smaller outcrops ˜50-500 m across at the floor of the canyon. Most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals. The plateau region northwest of Juventae Chasma is characterized by an abundance of light-toned layered deposits. One region contains two spectrally unique phases exhibiting a highly stratified, terraced pattern. CRISM spectra of one unit eroded into swirling patterns with arc-like ridges exhibit a narrow 2.23-?m band assigned to hydroxylated ferric sulfate. A thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate-bearing light-toned layered deposits. Hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units.

Bishop, Janice L.; Parente, Mario; Weitz, Catherine M.; Noe Dobrea, Eldar Z.; Roach, Leah H.; Murchie, Scott L.; McGuire, Patrick C.; McKeown, Nancy K.; Rossi, Christopher M.; Brown, Adrian J.; Calvin, Wendy M.; Milliken, Ralph; Mustard, John F.

2009-11-01

57

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

UK PubMed Central (United Kingdom)

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.

Teerapornpuntakit J; Wongdee K; Thongbunchoo J; Krishnamra N; Charoenphandhu N

2012-06-01

58

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

Directory of Open Access Journals (Sweden)

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

Gao Shu-guang; Cheng Ling; Li Kang-hua; Liu Wen-He; Xu Mai; Jiang Wei; Wei Li-Cheng; Zhang Fang-jie; Xiao Wen-feng; Xiong Yi-lin; Tian Jian; Zeng Chao; Sun Jin-peng; Xie Qiang; Lei Guang-hua

2012-01-01

59

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

UK PubMed Central (United Kingdom)

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

Gao SG; Cheng L; Li KH; Liu WH; Xu M; Jiang W; Wei LC; Zhang FJ; Xiao WF; Xiong YL; Tian J; Zeng C; Sun JP; Xie Q; Lei GH

2012-01-01

60

Clathrate hydrates  

Energy Technology Data Exchange (ETDEWEB)

Clathrate hydrates or gas hydrates are solid solutions. Water molecules are linked through hydrogen bonding and create cavities (host lattice) that can enclose a large variety of molecules (guests). There is no chemical bonding between the host water molecules and the enclosed guest molecule. The clathrate hydrate crystal may exist at temperatures below as well as above the normal freezing point of water. Clathrate hydrates have been a source of problems in the energy industry because the conditions at which oil and gas are produced, transported, and processed are frequently suitable for clathrate hydrate formation. Naturally occurring clathrate hydrates in the earth, containing mostly methane, are regarded as a future energy resource. These methane hydrates, however, are potentially threatening to the global environment if they decompose due to the greenhouse effect. Several innovative separations based on clathrate hydrate formation with applications in a variety of industrial sectors have been examined in the laboratory and pilot-plant stage. This paper reviews the status of current knowledge on clathrate hydrates. The emphasis is on the aspects related to technological problems and opportunities that arise from the artificial or natural formation and decomposition of clathrate hydrates. However, a description of the fundamentals of formation, properties, and structure is also presented, and aspects related to the molecular simulation are discussed. Studies on calorimetric properties, orientational disorder, guest-guest interactions, and nuclear magnetic resonance are not reviewed, but literature references are made. Clathrate hydrates arouse great interest within chemical and petroleum engineering, chemistry, earth, and environmental sciences.

Englezos, P. (Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Chemical Engineering)

1993-07-01

 
 
 
 
61

X-ray micro-analysis of the mineralization patterns in developing enamel in hamster tooth germs exposed to fluoride in vitro during the secretory phase of amelogenesis  

International Nuclear Information System (INIS)

The developing enamel from three-day-old hamster first maxillary (M1) molar tooth germs exposed to fluoride (F-) in vitro was analyzed for its mineral content by means of the energy-dispersive x-ray microanalysis technique. The aim of this study was to obtain semi-quantitative data on the F(-)-induced hypermineralization patterns in the enamel and to confirm that the increase in electron density observed in micrographs of F(-)-treated enamel is indeed due to an increase in mineral content in the fluorotic enamel. The tooth germs were explanted during the early stages of secretory amelogenesis and initially cultured for 24 hr in the presence of 10 ppm F- in the culture medium. The germs were then cultured for another 24 hr without F-. In order to compare the ultrastructural results directly with the microprobe data, we used the same specimens for both investigations. The net calcium counts (measurement minus background counts) in the analyses were used as a measure of the mineral content in the enamel. The aprismatic pre-exposure enamel, deposited in vivo before the onset of culture, was the most hypermineralized region in the fluorotic enamel, i.e., it contained the highest amount of calcium measured. The degree of the F(-)-induced hypermineralization gradually decreased (but was not abolished) in the more mature regions of the enamel. The unmineralized enamel matrix secreted during the initial F- treatment in vitro mineralized during the subsequent culture without F-. The calcium content in this enamel layer was in the same order of magnitude as that recorded for the newly deposited enamel in control tooth germs cultured without F-.

1989-01-01

62

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

International Nuclear Information System (INIS)

[en] 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.)

1980-01-01

63

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.

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

2011-01-01

64

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

Directory of Open Access Journals (Sweden)

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

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

2001-01-01

65

Gene array of primary human osteoblasts exposed to enamel matrix derivative in combination with a natural bone mineral.  

UK PubMed Central (United Kingdom)

OBJECTIVES: The application of an enamel matrix derivative (EMD) for regenerative periodontal surgery has been shown to promote formation of new cementum, periodontal ligament, and alveolar bone. In intrabony defects with a complicated anatomy, the combination of EMD with various bone grafting materials has resulted in additional clinical improvements, but the initial cellular response of osteoblasts coming in contact with these particles have not yet been fully elucidated. The objective of the present study was to evaluate the in vitro effects of EMD combined with a natural bone mineral (NBM) on a wide variety of genes, cytokines, and transcription factors and extracellular matrix proteins on primary human osteoblasts. MATERIAL AND METHODS: Primary human osteoblasts were seeded on NBM particles pre-coated with versus without EMD and analyzed for gene differences using a human osteogenesis gene super-array (Applied Biosystems). Osteoblast-related genes include those transcribed during bone mineralization, ossification, bone metabolism, cell growth and differentiation, as well as gene products representing extracellular matrix molecules, transcription factors, and cell adhesion molecules. RESULTS: EMD promoted gene expression of various osteoblast differentiation markers including a number of collagen types and isoforms, SMAD intracellular proteins, osteopontin, cadherin, alkaline phosphatase, and bone sialoprotein. EMD also upregulated a variety of growth factors including bone morphogenetic proteins, vascular endothelial growth factors, insulin-like growth factor, transforming growth factor, and their associated receptor proteins. CONCLUSION: The results from the present study demonstrate that EMD is capable of activating a wide variety of genes, growth factors, and cytokines when pre-coated onto NBM particles. CLINICAL RELEVANCE: The described in vitro effects of EMD on human primary osteoblasts provide further biologic support for the clinical application of a combination of EMD with NBM particles in periodontal and oral regenerative surgery.

Miron RJ; Bosshardt DD; Zhang Y; Buser D; Sculean A

2013-03-01

66

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; Nooredini Haji Ghorban; Hemmati Yousef

2011-01-01

67

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

International Nuclear Information System (INIS)

[en] 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

68

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

UK PubMed Central (United Kingdom)

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 C; Wolkers H; Rigét FF; Jensen JE; Teilmann J; Jenssen BM; Fuglei E; Ahlstrøm Ø; Dietz R; Muir DC; Jørgensen EH

2009-01-01

69

Calcium Aluminate Cement Hydration Model  

Directory of Open Access Journals (Sweden)

Full Text Available Calcium aluminate cement (AC) is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (?=5–20 °C) and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0) on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group), Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC). Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3) due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8)) based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1), was employed. Hydration kinetics after the induction period (? < 20 °C) had been successfully described (Fig. 4 and Table 2) by a proposed model (eq. (23)) which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq. (18)), the interaction at phase boundary was described by a bimolecular consumption of both reactants (eq. (19)), cement and free water, while the mass transfer mechanism was described relative to the limiting reactant (eq. (21)).Increasing temperature from 5 to 20 °C decreases the rate of nucleation and growth (NR) (Fig. 6), increases the rate of interaction (I) according to Arrhenius law (E12 ?43 kJ mol-1) (Fig. 7), and increases the rate of mass transfer (k) linearly (Fig. 8).

Ukrainczyk, N.; Dabi?, P.; Matusinovi?, T.

2011-01-01

70

The crystallization and destruction process of the secondary uranium minerals of 'Shelter' encasement  

International Nuclear Information System (INIS)

The composition of the secondary uranium minerals from the 'Shelter' encasement is obtained. It was shown that the leaching of radioactive nuclides from LFCM take place simultaneously with their mechanical destruction. The crystallization of the minerals caused by evaporation concentration of the alkali waters with the carbonate-sulfate-chloride composition. The minerals are a crystal-hydrates and may be exposed to the dehydration and destruction with the transition of the small particles to the aspirational aerosol disperse phase. The selective redistribution of the radioactive elements on the different kinds of matter take place in time under conditions of 'Shelter' encasement.

1996-01-01

71

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.

1996-01-01

72

Hydrates of natural gas  

Energy Technology Data Exchange (ETDEWEB)

A collection of Russian theories, experiments and field studies on natural gas hydrates is presented. The potential for discovering deposits of solid natural gas in permafrost zones and in some offshore areas is emphasized. The contents include: a study of hydrate properties and occurrences; problems of hydrate kinetics; preventing the formation of hydrates; hydrate deposits in porous rock strata; theoretical principles of gas production from hydrate fields; and utilization of hydrates for special purposes. (JMT)

Makogon, Y.F.

1981-01-01

73

Clathrate hydrates in nature.  

UK PubMed Central (United Kingdom)

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

Hester KC; Brewer PG

2009-01-01

74

ORGANIC-MINERAL COMPLEX  

UK PubMed Central (United Kingdom)

FIELD: agriculture. ^ SUBSTANCE: invention relates to the field of agriculture. Organic-mineral complex contains an organic substance, chalk, a phosphorite flour, a mineral fertiliser. The organic substance it contains is flax boon at the following ratio of components, wt %, by dry substance: flax boon - 96.43-98.94, chalk - 0.25-0.75, phosphorite flour - 0.20-1.00, mineral fertiliser - 0.61-1.82. The mineral fertiliser is ammonium nitrate, potassium nitrate and copper sulfate, 5-hydrate, at the wt % ratio accordingly of: 0.3-0.8:0.3-1.0:0.01-0.02. ^ EFFECT: application of organic-mineral complex makes it possible to increase crop capacity of plants, to expand assortment of fertile mixtures and to recycle flax production wastes. ^ 2 cl, 4 tbl

GRISHCHENKOVA VALENTINA ALEKSANDROVNA; BELOPUKHOV SERGEJ LEONIDOVICH; ZAKHARENKO ANDREJ VLADIMIROVICH; KUDRJAVTSEVA TAMARA NIKOLAEVNA; SHAPOVALOVA ELENA IVANOVNA

75

The hydratation of tertiary acetylene glycerin  

International Nuclear Information System (INIS)

[en] 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

1961-01-01

76

Electronic structure calculations of calcium silicate hydrates.  

Science.gov (United States)

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 ra...

P. A. Sterne A. Meike

1995-01-01

77

CFBC ash hydration studies  

Energy Technology Data Exchange (ETDEWEB)

Hydration studies on CFBC ashes have shown that the acetone technique to prevent hydration in stored samples is relatively effective, only allowing some slight degree of hydration over days in the presence of excess water. In the presence of large excesses of water sufficient to control temperature increases, the degree of bulk mixing has no effect on the degree of hydration, which is shown to be relatively slow at ambient conditions, taking hours to complete. Finally, the effect of salt addition on hydration has been shown to be negligible at the low levels typical of wastewater, but there may be effects at ion concentrations typical of seawater. This work suggests that experience gained from lime hydration should be applied with caution to studies on hydration of CFBC ashes. 18 refs., 5 tabs.

Edward J. Anthony; Lufei Jia; Yinghai Wu [CANMET Energy Technology Centre Ottawa (CETC), Ottawa, ON (Canada). Natural Resources Canada

2005-08-01

78

Mineral hydrolysis kinetics  

Energy Technology Data Exchange (ETDEWEB)

Dissolution rate laws for silicate mineral weathering can be related to kinetics of ligand-exchange reactions. This relation is being tested with an experimental/analytical/theoretical program for measuring the dissolution kinetics of orthosilicate minerals for use in ionic modeling and molecular dynamics computer simulations of solid, aqueous solution, and solid/liquid interface. To date, dissolution rate have been measured for a suite of endmember and mixed-cation orthosilicate minerals (both olivine and willemite structures) as well as a few inosilicate minerals (pyroxenes). Dissolution rates appear to correlate well with solvent exchange rates around the hydrated divalent cations. Siloxane (Si-O-Si) bonds are relatively unreactive at low pH`s close to zero point of neutral charge for quartz. The correlation suggests that silicic acid would be released from the reacting surfaces after protonation and hydration of bonds between divalent metals and structural oxygens; congruent dissolution is confirmed by Rutherford backscattered analysis of the near-surface of an acid-reacted forsterite. In the ionic modeling, except for liebenbergite, there is a general trend of increasing lattice energy with decreasing dissolution rate for endmember and mixed-cation orthosilicate minerals at pH 2. 3 figs, 4 refs.

Westrich, H.R.; Cygan, R.T.; Arnold, G.W. [Sandia National Labs., Albuquerque, NM (United States); Casey, W.H. [California Univ., Davis, CA (United States). Dept. of Land, Air, and Water Resources

1993-07-01

79

Methane hydrate; deep water drilling hazard  

Energy Technology Data Exchange (ETDEWEB)

Methane hydrate is a crystallized combination of methane and water that can be found only under certain pressure and temperature conditions. If hydrates are exposed to conditions outside those that ensure their stability, methane explodes into its equivalent gaseous volume. This is a hazard during offshore drilling, but if operators are aware of the possibility of hydrate formation, they can easily avoid this hazard. The hazard is greatest in shallow water if methane hydrates are encountered during the drilling of the conductor pipe before the BOP is installed. Fortunately, the high acoustic impedance of these accumulations makes them easily recognizable. Methane hydrates found in deep water are not as dangerous during drilling operations because of the great pressure; however, there is a hazard if natural gas is introduced to seawater under these conditions. The Macondo Well blowout in the Gulf of Mexico illustrated in a striking way the danger of hydrate formation when methane and water are mixed at 4 degree C and at high pressure.

Kalmanovitch, Norman [Independent Geophysical Consultant Calgary, Alberta (Canada)], email: kalhnd@shaw.ca

2011-07-01

80

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. Copyright 2007 by the American Geophysical Union.

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

2007-01-01

 
 
 
 
81

Hydration process of nuclear-waste glass: an interim report  

Energy Technology Data Exchange (ETDEWEB)

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 240/sup 0/C. 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.

Bates, J.K.; Jardine, L.J.; Steindler, M.J.

1982-07-01

82

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

1982-01-01

83

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.

Snyder K.A.; Stutzman P.E.; Philip J.; Esh D.

2013-01-01

84

Influence of hydrating agents on the hydration of industrial magnesium oxide Influence of hydrating agents on MgO hydration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

BACKGROUND: The influence of different hydrating agents on the pH of the hydrating solutions, rate of hydration of MgO to Mg(OH)2 and product surface area was studied as a function of temperature of hydration. Hydrating agents used were aqueous solutions of ammonium chloride, magnesium acetate, magn...

Matabola, Kgabo P.; Van der Merwe, Elizabet Margaretha; Strydom, Christien A. (Christiena Adriana); Labuschagne, Frederick J.W.

85

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

1994-01-01

86

Hydration process of cement containing fly ash and silica fume: The first 24 hours  

Energy Technology Data Exchange (ETDEWEB)

Results from studies on the early hydration (till the 24th hour) of cements mixed with fly ash, silica fume or a combination of both, called Pozzolit, are presented. The active role of the Pozzolit mineral additive was revealed by DTA, XRD and IRS analyses. The effect of the additive is expressed in increased total amount of hydration products and decreased portlandite content.

Lilkov, V. [Univ. of Mining and Geology, Sofia (Bulgaria); Dimitrova, E.; Petrov, O.E. [Bulgarian Academy of Sciences, Sofia (Bulgaria)

1997-04-01

87

Class H cement hydration at 180 °C and high pressure in the presence of added silica  

Energy Technology Data Exchange (ETDEWEB)

Under deep oil-well conditions of elevated temperature and pressure, crystalline calcium silicate hydrates are formed during Portland cement hydration. The use of silica rich mineral additives leads to the formation of crystalline hydrates with better mechanical properties than those formed without the additive. The effects of silica flour, silica fume (amorphous silica), and a natural zeolite mixture on the hydration of Class H cement slurries at 180 C under externally applied pressures of 7 and 52 MPa are examined in real time using in-situ synchrotron X-ray diffraction. For some compositions examined, but not all, pressure was found to have a large effect on the kinetics of crystalline hydrate formation. The use of silica fume delayed both C{sub 3}S hydration and the formation of crystalline silicate hydrates compared to what was seen with other silica sources.

Jupe, Andrew C.; Wilkinson, Angus P.; Luke, Karen; Funkhouser, Gary P. (Halliburton); (GIT)

2008-10-06

88

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

Science.gov (United States)

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

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

2004-01-01

89

Hydration rate of obsidian.  

UK PubMed Central (United Kingdom)

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

Friedman I; Long W

1976-01-01

90

Hydration rate of obsidian.  

Science.gov (United States)

The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years. PMID:17782901

Friedman, I; Long, W

1976-01-30

91

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

92

Hydrated vanadium pentoxide  

International Nuclear Information System (INIS)

[en] 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

1986-01-01

93

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

94

Obsidian hydration dating of volcanic events  

Science.gov (United States)

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

Friedman, I.; Obradovich, J.

1981-01-01

95

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

96

Introduction to Mineral Equilibria  

Science.gov (United States)

This is short problem set to be used in class. It helps focus discussion, while providing a starting point for discussing mineral reactions and phase diagrams. Students are exposed to ternary composition diagrams and to phase diagrams. They are also introduced to the phase rule, although in quite a superficial way.

Perkins, Dexter

97

Hydrated silica on Mars: Combined analysis with near-infrared and thermal-infrared spectroscopy  

Science.gov (United States)

Hydrated silica is found in a variety of martian deposits within aqueously altered mineral suites. Its common occurrence is attributed to its ease of formation in different weathering environments. Because of its presence in disparate units, hydrated silica makes a good tracer mineral to compare otherwise dissimilar martian deposits and relate their relative degrees of aqueous alteration. This work combines near-infrared and thermal-infrared spectroscopy to determine the relative degree of crystallinity and bulk SiO2 abundance of surfaces containing hydrated silica. A range of crystalline structures are present, from non-crystalline (hydrated glass) to weakly crystalline (opal) to crystalline (quartz), implying a range in the maturity of these silica deposits. However, bulk SiO2 contents show less diversity, with most martian hydrated silica deposits having SiO2 abundances similar to Surface Type 2 (basaltic andesite or weathered basaltic composition)—a widespread and common surface composition that suggests limited interaction with water. We also find that hydrated silica crystallinity—as a proxy for degree of alteration—is correlated with the geochemistry of the deposit as inferred by its associated minerals: highly crystalline hydrated silica is found with Fe/Mg-phyllosilicates, moderately crystalline hydrated silica is associated with Al-phyllosilicates, and poorly crystalline phases are associated with sulfates. This corroborates previous predictions of the waning of surficial water from the Noachian ? Hesperian and demonstrates the usefulness of hydrated silica as a stand-alone mineral for predicting the degree of alteration of ancient mineral suites.

Smith, Matthew R.; Bandfield, Joshua L.; Cloutis, Edward A.; Rice, Melissa S.

2013-04-01

98

The nature of gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates have impacted the oil and gas industry since 1934, when they were first found to plug pipelines. Today we know that in deep oceans and in permafrost, very substantial gas reserves are present in hydrated form. Concerns are being raised about in situ dissociation for both energy and greenhouse implications upon methane release. In Japan work is underway to consider the storage of carbon dioxide, concentrated in clathrates. This talk will deal with some basic questions. Why should we be interested in gas hydrates? What are gas hydrates? How do gas hydrates form? How might hydrates impact on the energy/environmental picture?

Ussler, W.; Borowski, W.

1995-12-31

99

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 established. The modelled phase development with ongoing hydration agrees well with the experimental findings.

2010-01-01

100

Ore Minerals  

Science.gov (United States)

This three part lab introduces sulfides and other ore minerals. Part one - Ore Minerals: Students fill in a table giving the metal, formula, and mineral group of several ore minerals. Part two - Box of Rocks: Students examine trays of ore minerals and record their physical properties, composition, habit, occurence, economic value, and use and answer questions about color, luster, density, transparency, and availability. Part three - Famous Digs: Students answer a series of questions related to famous ore deposits.

Perkins, Dexter

 
 
 
 
101

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- < K- < Cs-smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces. PMID:19746709

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

2009-08-15

102

Role of interlayer hydration in lincomycin sorption by smectite clays.  

UK PubMed Central (United Kingdom)

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- < K- < Cs-smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces.

Wang C; Ding Y; Teppen BJ; Boyd SA; Song C; Li H

2009-08-01

103

A hydrate formation inhibitor  

Energy Technology Data Exchange (ETDEWEB)

In order to expand the range of temperature of the use of a hydrate formation inhibitor (IG) of natural and accompanying gases based on ethylenglycol with a preservation of the inhibiting properties on a high level, acetone is additionally introduced. The ratio of components in percent is: 20 to 40 acetone and ethyeleglycol, the remainder. The use of the hydrate formation inhibitor of the cited composition makes it possible to reduce the freezing point from -12.3 to 37 to 59 degrees and the viscosity from 19.9 to 3 to 5 centipoise, which expands the capabilities of its use, especially in the regions of the extreme North. Moreover, the proposed hydrate formation inhibitor is 15 to 20 percent cheaper than ethylenglycol.

Malenko, E.V.

1983-01-01

104

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

105

Adhesion of Hydrated Silicate Films.  

Science.gov (United States)

We used fracture mechanics test techniques to measure the adhesive bond energy formed between hydrated silica glass surfaces and silicate species deposited from solution. In the case of silicate surfaces hydrated in room temperature water vapor, intermole...

T. A. Michalske K. D. Keefer

1988-01-01

106

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

UK PubMed Central (United Kingdom)

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).

Meier DC; Davis JM; Vicenzi EP

2011-10-01

107

Interlayer Spaces Associated with Hydration and Dehydration in Synthetic Saponite  

International Nuclear Information System (INIS)

Positron annihilation lifetime spectroscopy was conducted for a synthetic saponite to investigate hydration and dehydration behaviour occurring in nanoscale interlayer spaces. Long positron lifetime of ? 24 ns was observed with the intensity of ? 8 % when the sample is evacuated at ? 10-5 Torr. The radius of open nanospace evaluated from the positron lifetime is ? 10 A, which corresponds to the interlayer spaces of saponite. The open nanospace increases up to 13 % after baking at 423 K for 8 h under the vacuum. The present results imply that positron annihilation spectroscopy is powerful tool to investigate hydration and dehydration behavior through the local structural changes in the interlayer spaces of clay minerals.

2010-01-01

108

Interlayer Spaces Associated with Hydration and Dehydration in Synthetic Saponite  

Science.gov (United States)

Positron annihilation lifetime spectroscopy was conducted for a synthetic saponite to investigate hydration and dehydration behaviour occurring in nanoscale interlayer spaces. Long positron lifetime of ~ 24 ns was observed with the intensity of ~ 8 % when the sample is evacuated at ~ 10-5 Torr. The radius of open nanospace evaluated from the positron lifetime is ~ 10 Å, which corresponds to the interlayer spaces of saponite. The open nanospace increases up to 13 % after baking at 423 K for 8 h under the vacuum. The present results imply that positron annihilation spectroscopy is powerful tool to investigate hydration and dehydration behavior through the local structural changes in the interlayer spaces of clay minerals.

Sato, K.; Fujimoto, K.; Nakata, M.; Shikazono, N.

2010-11-01

109

Method of preventing hydrate formation in gas field equipment  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to improve prevention of hydrate formation with simultaneous prevention of mineral salt depositing in the gas well and well equipment. This goal is achieved because according to the method of preventing hydrate formation in the gas-field equipment, methanol before injection into the well is treated with alkali metal hydroxide or ammonium hydroxide to pH no less than 8, and then salt-deposit inhibitor in a concentration of 2.5-50.0 mg/1 of bed water. In addition, a salt-depositing inhibitor is added to the methanol.

Dytyuk, L.T.; et al.; Akhmetov, V.N.; Barsukov, A.V.; Eskin, A.M.; Samakayev, R.Kh.

1984-01-01

110

Effect of flotation reagents on hydration of pit-coal and limestone surfaces. Part II. The effect of flocculants on hydration of pit-coal and limestone surfaces  

Energy Technology Data Exchange (ETDEWEB)

The results are presented of investigations of hydration of coal from the Lublin Basin and limestone which were previously covered with certain flocculants from the Magnafloc series. It was found that the influence of the flocculants on hydration of the mineral surface depends on the nature of the reagent and its concentration. The possibilities and conditions of the application of flocculants in the coal cleaning process are discussed.

Staszczuk, P.

1983-03-01

111

Obsidian hydration profile measurements using a nuclear reaction technique  

Science.gov (United States)

AMBIENT water diffuses into the exposed surfaces of obsidian, forming a hydration layer which increases in thickness with time to a maximum depth of 20-40 ??m (ref. 1), this layer being the basic foundation of obsidian dating2,3. ?? 1974 Nature Publishing Group.

Lee, R. R.; Leich, D. A.; Tombrello, T. A.; Ericson, J. E.; Friedman, I.

1974-01-01

112

Class H cement hydration at 180 deg. C and high pressure in the presence of added silica  

International Nuclear Information System (INIS)

Under deep oil-well conditions of elevated temperature and pressure, crystalline calcium silicate hydrates are formed during Portland cement hydration. The use of silica rich mineral additives leads to the formation of crystalline hydrates with better mechanical properties than those formed without the additive. The effects of silica flour, silica fume (amorphous silica), and a natural zeolite mixture on the hydration of Class H cement slurries at 180 deg. C under externally applied pressures of 7 and 52 MPa are examined in real time using in-situ synchrotron X-ray diffraction. For some compositions examined, but not all, pressure was found to have a large effect on the kinetics of crystalline hydrate formation. The use of silica fume delayed both C3S hydration and the formation of crystalline silicate hydrates compared to what was seen with other silica sources.

2008-01-01

113

Scanning electron microscopy investigations of laboratory-grown gas clathrate hydrates formed from melting ice, and comparison to natural hydrates  

Science.gov (United States)

Scanning electron microscopy (SEM) was used to investigate grain texture and pore structure development within various compositions of pure sI and sII gas hydrates synthesized in the laboratory, as well as in natural samples retrieved from marine (Gulf of Mexico) and permafrost (NW Canada) settings. Several samples of methane hydrate were also quenched after various extents of partial reaction for assessment of mid-synthesis textural progression. All laboratory-synthesized hydrates were grown under relatively high-temperature and high-pressure conditions from rounded ice grains with geometrically simple pore shapes, yet all resulting samples displayed extensive recrystallization with complex pore geometry. Growth fronts of mesoporous methane hydrate advancing into dense ice reactant were prevalent in those samples quenched after limited reaction below and at the ice point. As temperatures transgress the ice point, grain surfaces continue to develop a discrete "rind" of hydrate, typically 5 to 30 ??m thick. The cores then commonly melt, with rind microfracturing allowing migration of the melt to adjacent grain boundaries where it also forms hydrate. As the reaction continues under progressively warmer conditions, the hydrate product anneals to form dense and relatively pore-free regions of hydrate grains, in which grain size is typically several tens of micrometers. The prevalence of hollow, spheroidal shells of hydrate, coupled with extensive redistribution of reactant and product phases throughout reaction, implies that a diffusion-controlled shrinking-core model is an inappropriate description of sustained hydrate growth from melting ice. Completion of reaction at peak synthesis conditions then produces exceptional faceting and euhedral crystal growth along exposed pore walls. Further recrystallization or regrowth can then accompany even short-term exposure of synthetic hydrates to natural ocean-floor conditions, such that the final textures may closely mimic those observed in natural samples of marine origin. Of particular note, both the mesoporous and highly faceted textures seen at different stages during synthetic hydrate growth were notably absent from all examined hydrates recovered from a natural marine-environment setting.

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

2004-01-01

114

Aluminum Sulfate 18 Hydrate  

Science.gov (United States)

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

Young, Jay A.

2004-01-01

115

Study of heat transfer characteristics during dissociation of gas hydrates in porous media  

Energy Technology Data Exchange (ETDEWEB)

An experimental technique was developed to measure the rate of formation and dissociation of hydrates in porous media. In the first phase of the work, hydrates of propane and methane were studied. Propane hydrate cores were formed by contacting liquid propane with compacted porous ice cores at 274 K for 24 to 100 hours, whereas the formation of methane hydrates was achieved by contacting ice cores with gaseous methane at about 7000 kPa and 274 K, for 24 to 200 hours. These hydrate cores were dissociated by circulating warm water over the top of the core, under controlled temperatures and pressures. The major findings of these experiments are as follows: 1) the phenomena of dissociation of hydrates to liquid water and gas is similar to nucleate boiling of liquids; 2) the rate of dissociation of hydrates at constant ..delta..T, is directly proportional to the area of hydrates exposed to the warm fluid or the composition of hydrates in the core; and 3) the rate of heat transfer and dissociation increase with increase in pressure and the rate of circulation of the warm fluid. Unified correlations for heat transfer and dissociation rates were successfully obtained for both methane and propane hydrate dissociation. These correlations will be useful to predict the rate of dissociation and gas production in hydrate reservoirs. In the second phase of his work, in order to simulate the conditions of hydrate dissociation in the earth, methane hydrates were formed and dissociated in unconsolidated cores of sand. The results of these experiments have demonstrated that the heat transfer resistance of the media (rock) plays an important role in dissociation of hydrates in earth.

Kamath, V.A.

1984-01-01

117

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

118

Formation of submarine gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-03-01

119

Is Obsidian Hydration Dating Affected by Relative Humidity?  

Science.gov (United States)

Experiments carried out under temperatures and relative humidities that approximate ambient conditions show that the rate of hydration of obsidian is a function of the relative humidity, as well as of previously established variables of temperature and obsidian chemical composition. Measurements of the relative humidity of soil at 25 sites and at depths of between 0.01 and 2 m below ground show that in most soil environments, at depths below about 0.25 m, the relative humidity is constant at 100%. We have found that the thickness of the hydrated layer developed on obsidian outcrops exposed to the sun and to relative humidities of 30-90% is similar to that formed on other portions of the outcrop that were shielded from the sun and exposed to a relative humidity of approximately 100%. Surface samples of obsidian exposed to solar heating should hydrate more rapidly than samples buried in the ground. However, the effect of the lower mean relative humidity experiences by surface samples tends to compensate for the elevated temperature, which may explain why obsidian hydration ages of surface samples usually approximate those derived from buried samples.

Friedman, I.; Trembour, F. W.; Smith, G. I.; Smith, F. L.

1994-01-01

120

Hydration of cyanin dyes  

Science.gov (United States)

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

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

2010-03-01

 
 
 
 
121

Hydration of cyanin dyes.  

UK PubMed Central (United Kingdom)

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

Calzolari A; Monti S; Ruini A; Catellani A

2010-03-01

122

[Synthetic mineral fibers  

UK PubMed Central (United Kingdom)

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.

Boillat MA

1999-03-01

123

[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

124

Predicting pipeline hydrate formation  

Energy Technology Data Exchange (ETDEWEB)

A significant improvement in thermodynamic modelling of the blockage of pipelines by gas hydrates is reported which agrees well with experimental data. It also offerers advantages over commercial flowsheet simulators. This should help to reduce safety hazards and operational problems in North Sea oil and gas production facilities. The reliability of the model has been tested by comparison with data from experiment and literature. (UK)

Tohidi, B.; Danesh, A.; Todd, A. [Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Petroleum Engineering

1997-09-25

125

Effect of flotation reagents on hydration of pit-coal and limestone surfaces. Pt. 2  

Energy Technology Data Exchange (ETDEWEB)

In this paper the author has presented the results of the investigations of hydration of pit-coal (from the Lublin Coal Basin) and limestone which were previously covered with certain flocculants from the Magnafloc series. It has been found that the influence of the flocculants on hydration of the mineral surface depends on the nature of the reagent and its concentration. The possibilities and conditions of the application of flocculants in the pit-coal enrichment process have been discussed.

Staszcuk, P.

1983-03-15

126

Hydration of lithium ?-alumina  

International Nuclear Information System (INIS)

[en] The hydration reaction of Li ?-alumina has been studied using infrared measurements of large single crystals equilibrated at controlled water vapor pressure (2--80 kPa) and temperature (250--450 0C) conditions. The equilibrium H2O concentrations in the conduction plane can be carried continuously and reversibly up to a saturation limit of about 1.8 H2O per unit cell. Values of the enthalpy and entropy for the hydration reaction at 300--450 0C were determined to be ?H = -102 kJ/mol and ?S = -167 J/mol K. In Li ?-alumina, some of the H2O dissociates to form OH- ions and H+ ions which are bound to lattice oxygen ions; the enthalpy for the dissociation reaction is approx.10 kJ/mol. In addition to OH-, H3O+ and H5O+2 species have been identified from the observed change in the equilibrium concentration with the water vapor pressure. The relative concentrations of the different types of OH- species depend on the sample age. The hydration enthalpy for Na ?-alumina of approx.-84 kJ/mol was determined from a similar study

1982-11-15

127

Acid-catalyzed hydration of alkynes in aqueous microemulsions.  

UK PubMed Central (United Kingdom)

Terminal aromatic alkynes are converted rapidly into ketones in a regioselective manner by treatment of their microemulsions with 0.33?M mineral acid between 80 and 140?°C. Internal and aliphatic acetylenes are likewise hydrated, but require longer reaction periods. The products are easily isolated from the reaction mixtures by phase separation. Replacement of H2 O by D2 O leads to the formation of trideuteriomethyl ketones.

Nairoukh Z; Avnir D; Blum J

2013-03-01

128

Mineral slurries  

Energy Technology Data Exchange (ETDEWEB)

A pumpable slurry of mineral particles, e.g. coal, in water contains 50 to 85% by weight of mineral particles based on the combined weight of mineral particles and water. The mineral component contains at least 30% by weight of coarse particles having a particle size in the range 5 to 50 mm, 10 to 40% by weight of fine particles having a particle size less than 200 microns, and the balance to 100% of intermediate sized particles. The slurry is stable without the use of additives and can be pumped through a pipeline.

Baker, P.; Brookes, D.; Johnson, M.

1987-04-14

129

Structural studies of gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

An overview of recent structural work focusing on gas hydrates (clathrate hydrates) -- inclusion compounds in which a water host structure encages small guest molecules such as methane, -- is given, with specific focus on gas hydrates with guest molecules that are gaseous at ambient conditions. Both crystallographic structure and the microstructure of gas hydrates are discussed, concentrating on carbon dioxide and methane. Pressure-dependent molecular structure of methane clathrate hydrate, using laboratory-made hydrogenous and deuterated samples, were investigated by neutron and hard X-ray synchrotron diffraction experiments; their isothermal compressibilities were also studied and reported on. Cage filing of carbon dioxide and methane hydrate was determined and compared with predictions from the statistical thermodynamic theory of Van der Waals and Platteeuw. Field emission scanning electron microscopic study of the microstructural properties of the samples showed them to be at least partly meso-to-macro-porous; the existence of an interrelationship between microstructures and reaction kinetics was also revealed. The overall conclusion was that X-ray diffraction is the best method for detecting and quantifying stable and metastable gas hydrate phases, and that all gas hydrates formed with an excess of gas yield at least a partly porous microstructure which has a measurable influence on the physical properties of such gas hydrates. 35 refs., 14 figs.

Klapproth, A.; Goreshnik, E.; Staykova, D.; Klein, H.; Kuhs, W. F. [Universitat Gottingen, GZG Abteilung Kristallographie, Gottingen (Germany)

2003-01-01

130

Hydration studies of Bentonite clay  

Science.gov (United States)

Bentonite clay when hydrated increases its volume several fold to form a pliable mass. X-ray diffraction showed that as hydration increases, the crystalline peaks due to kaolinite, calcite and quartz are gradually replaced by an amorphous background while the crystalline reflections of montmorillonite remain. Hydration is known to occur through the inclusion of the hydroxyl radical within the layered structure of the clay. Small Angle Neutron Scattering (SANS) data on the dry and hydrated clay confirm the water uptake as found from the level of incoherent scattering at higher values of Q.

Desai, Reshma R.; Erwin Desa, J. A.; Aswal, V. K.

2012-06-01

131

Mineral admixtures in cement and concrete  

CERN Multimedia

Written for structural engineers, this book explains how micro-structurally engineered concrete can substantially enhance the durability and service life of concrete structures. The text addresses the sustainable development of cement and the construction industry and provides an understanding of the materials aspects of mineral admixtures and their positive impact on the hydration and durability of concrete in an effort to encourage greater utilization of other wastes in cement and concrete. The author explains the development of strength-giving chemical phases during hydration and the refine

Bapat, Jayant D

2012-01-01

132

Assessment of chromium content of feedstuffs, their estimated requirement, and effects of dietary chromium supplementation on nutrient utilization, growth performance, and mineral balance in summer-exposed buffalo calves (Bubalus bubalis).  

Science.gov (United States)

This study was conducted to determine the chromium content of different feedstuffs, their estimated requirement, and effect of dietary Cr supplementation on nutrient intake, nutrient utilization, growth performance, and mineral balance in buffalo calves during summer season. Levels of Cr was higher in cultivated fodder, moderate in cakes and cereal grains, while straw, grasses, and non-conventional feeds were poor in Cr content. To test the effect of Cr supplementation in buffalo calves, 0, 0.5, 1.0, and 1.5 ppm of inorganic Cr were fed to 24 buffalo calves. Buffalo calves were randomly assigned to four treatments (n = 6) and raised for 120 days. A metabolic trial for a period of 7 days was conducted after 3 months of dietary treatments. Blood samples were collected at fortnight interval for plasma mineral estimation. The results suggested that dietary Cr supplementation in summer did not have any affects (P > 0.05) on feed consumption, growth performance, nitrogen balance, and physiological variables. However, dietary Cr supplementation had significant effect (P 0.05) balance and plasma levels of other trace minerals. The estimated Cr requirement of buffalo calves during summer season was calculated to be 0.044 mg/kg body mass and 10.37 ppm per day. In conclusion, dietary Cr supplementation has regardless effect on feed consumption, mass gain, and nutrient utilization in buffalo calves reared under heat stress conditions. However, supplementation of Cr had positive effect on its balance and plasma concentration without interacting with other trace minerals. PMID:23963742

Kumar, Muneendra; Kaur, Harjit; Tyagi, Amrish; Mani, Veena; Deka, Rijusmita Sarma; Chandra, Gulab; Sharma, Vijay Kumar

2013-08-21

133

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

Energy Technology Data Exchange (ETDEWEB)

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

None

2010-07-01

134

Micellar gas hydrate storage process  

Energy Technology Data Exchange (ETDEWEB)

Results are presented on a gas-hydrate project sponsored by the U.S. Department of Energy to develop alternative natural gas storage. Directed toward safe, aboveground storage of natural gas, such as use during electrical power plant peak loads, the process features micellar solutions that rapidly form and self-pack hydrates on specially designed heat-exchanger-adsorption plates. The project is discussed from laboratory inception through pilot-plant testing that is currently underway. Anionic surfactant acts as nucleating sites for gas hydrate crystals. Probable mechanism is that surfactant micelles solubilize natural gas components in their core, accumulate structured water at their peripheral hydrophilic heads, and adsorb with attached developing hydrate crystals onto cold-metal surfaces at the gas-water interface. Interstitial water of the packed hydrate particles reacts to completion. By minimizing labor and maintenance, the non-stirred system enhances economics. As hydrates form and self-pack, processing requires only that natural gas pressure be maintained on the formation/storage tank until filled with hydrates; gas may be released by altering temperature of coolant through adsorption plates. Discussed are the principles of the design of the surfactant process that stores 5,000 scf natural gas in gas hydrates; pilot plant test results are presented. (Author)

Rogers, Rudy E.; Zhong, Yu; Etheridge, J.A.; Arunkumar, R.; Pearson, L.E.; Hogancamp, T.K.

2005-07-01

135

Hydration Affects Both Harmonic and Anharmonic Nature of Protein Dynamics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To understand the effect of hydration on protein dynamics, inelastic neutron-scattering experiments were performed on staphylococcal nuclease samples at differing hydration levels: dehydrated, partially hydrated, and hydrated. At cryogenic temperatures, hydration affected the collective motions with...

Nakagawa, H.; Joti, Y.; Kitao, A.; Kataoka, M.

136

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.

Sutton Rebecca; Sposito Garrison

2002-01-01

137

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

138

Influence of surface chemistry and charge on mineral-RNA interactions.  

UK PubMed Central (United Kingdom)

We present the results of large-scale molecular simulations, run over several tens of nanoseconds, of 25-mer sequences of single-stranded ribonucleic acid (RNA) in bulk water and at the surface of three hydrated positively charged MgAl layered double hydroxide (LDH) minerals. The three LDHs differ in surface charge density, through varying the number of isomorphic Al substitutions. Over the course of the simulations, RNA adsorbs tightly to the LDH surface through electrostatic interactions between the charged RNA phosphate groups and the alumina charge sites present in the LDH sheet. The RNA strands arrange parallel to the surface with the base groups aligning normal to the surface and exposed to the bulk aqueous region. This templating effect makes LDH a candidate for amplifying the population of a known RNA sequence from a small number of RNAs. The structure and interactions of RNA at a positively charged, hydroxylated LDH surface were compared with those of RNA at a positively charged calcium montmorillonite surface, allowing us to establish the comparative effect of complexation and water structure at hydroxide and silicate surfaces. The systems were studied by computing radial distribution functions, atom density plots, and radii of gyration, as well as visualization. An observation pertinent to the role of these minerals in prebiotic chemistry is that, for a given charge density on the mineral surface, different genetic sequences of RNA adopt different configurations.

Swadling JB; Suter JL; Greenwell HC; Coveney PV

2013-02-01

139

PROCESS FOR HYDRATE INHIBITOR REGENERATION  

UK PubMed Central (United Kingdom)

The invention provides a process for the production of a lean liquid hydrate inhibitor composition from a rich liquid hydrate inhibitor composition in which the liquid hydrate inhibitor has a boiling point above that of water, which process comprises: (a) feeding said rich liquid hydrate inhibitor composition to a first distillation vessel (b) withdrawing a water and inhibitor containing vapour from said first distillation vessel and feeding it to a second distillation vessel (c) withdrawing water vapour from said second distillation vessel (d) withdrawing a lean hydrate inhibitor composition from said second distillation vessel in liquid form (e) withdrawing a lean hydrate inhibitor composition from said first distillation vessel in liquid form (f) withdrawing liquid from said first distillation vessel and removing solids therefrom wherein the withdrawal of steps (e) and (f) may be of a single liquid stream and wherein at least a portion of the lean hydrate inhibitor composition withdrawn from said first distillation vessel is not recycled into said first distillation vessel.

KAASA BAARD; BILLINGTON PER HALVARD

140

Hydrated hydride anion clusters.  

UK PubMed Central (United Kingdom)

On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion hydrated by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed.

Lee HM; Kim D; Singh NJ; Ko?aski M; Kim KS

2007-10-01

 
 
 
 
141

Hydrated hydride anion clusters.  

Science.gov (United States)

On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion hydrated by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed. PMID:17979342

Lee, Han Myoung; Kim, Dongwook; Singh, N Jiten; Ko?aski, Maciej; Kim, Kwang S

2007-10-28

142

Adsorption and heterocoagulation of nonionic surfactants and latex particles on cement hydrates.  

UK PubMed Central (United Kingdom)

The adsorption of nonionic surfactants of the alkyl-phenol-poly(ethylene oxide) family and of acrylic latex particles on several anhydrous (but hydrating) or fully hydrated mineral phases of Portland cement was studied. No or negligible adsorption of the surfactant was observed. This was assigned to the ionized character of the surface silanol groups in calcium-silicate-hydrates and to the strongly ionic character of the OH groups in calcium hydroxide and in the calcium-sulfoaluminate-hydrates, which prevents the formation of surface-ethoxy hydrogen bonds. In contrast, provided they are properly stabilized by the surfactant, the latex particles form a loose monolayer on the surface of hydrating tricalcium silicate particles. The attractive interaction between the positive mineral surface and the negative latex surface appears to be the driving force for adsorption. In line with this, adsorption is reduced by sulfate anions, which adsorb specifically onto the silicate surface. Compared to tricalcium silicate, portlandite and gypsum interact only marginally with the latex particles. Our results show that the stability of the nonionic surfactant/latex/cement systems is essentially controlled by the latex colloidal stability and the latex-cement interactions, the surfactant having little direct interaction, if any, with the mineral surfaces.

Merlin F; Guitouni H; Mouhoubi H; Mariot S; Vallée F; Van Damme H

2005-01-01

143

Fluidity of bound hydration layers.  

UK PubMed Central (United Kingdom)

We have measured the shear forces between solid surfaces sliding past each other across aqueous salt solutions, at pressures and concentrations typical of naturally occurring systems. In such systems the surface-attached hydration layers keep the compressed surfaces apart as a result of strongly repulsive hydration forces. We find, however, that the bound water molecules retain a shear fluidity characteristic of the bulk liquid, even when compressed down to films 1.0 +/- 0.3 nanometer thick. We attribute this to the ready exchange (as opposed to loss) of water molecules within the hydration layers as they rub past each other under strong compression.

Raviv U; Klein J

2002-08-01

144

Heat of hydration for fly ash as a predictive test  

Energy Technology Data Exchange (ETDEWEB)

Coal combustion residues are commonly used in construction and for other engineering applications. These materials are complex and exhibit highly variable characteristics. Coal combustion fly ash, the most utilized of these materials, is commonly classified by its pozzolanic or cementitious properties. These properties are generally determined and monitored by empirical physical test procedures required for certification of these materials for use as a mineral admixture in cement. The current classification system does not provide a continuous scale rating for pozzolanic/cementitious behavior for these materials, or adequate information to assess the reactivity of these materials outside of their limited use in cement and concrete products. A test procedure, based on the heat of hydration, has been developed at the Energy and Environmental Research Center to more accurately assess the reactivity and behavior of these materials for utilization. The technique employs either a Dewar flask or a modified oxygen bomb calorimeter to determine the temperature change and rate of change after the addition of water to fly ash. X-ray diffraction is performed on the hydrated material following the hydration test to follow mineralogical changes as a result of the hydration process. A study of coal fly ash samples is underway to determine whether correlations exist between the temperature change and empirical test results. A protocol has been developed to assist in an improved classification scheme for coal fly ash.

Hassett, D.J.

1995-12-31

145

Obsidian hydration dates glacial loading?  

UK PubMed Central (United Kingdom)

Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

Friedman I; Pierce KL; Obradovich JD; Long WD

1973-05-01

146

Obsidian Hydration: A New Paleothermometer  

Energy Technology Data Exchange (ETDEWEB)

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

Anovitz, Lawrence {Larry} M [ORNL; Riciputi, Lee R [ORNL; Cole, David R [ORNL; Fayek, Mostafa [ORNL; Elam, J. Michael [University of Tennessee, Knoxville (UTK)

2006-01-01

147

Obsidian hydration dates glacial loading?  

Science.gov (United States)

Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow. PMID:17806883

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

1973-05-18

148

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; John S. Tse

2010-01-01

149

Hydration water and microstructure in calcium silicate and aluminate hydrates  

International Nuclear Information System (INIS)

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.

2006-09-13

150

Hydration dependent dynamics in RNA  

International Nuclear Information System (INIS)

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

2009-01-01

151

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

152

Interlayer Spaces Associated with Hydration and Dehydration in Synthetic Saponite  

Energy Technology Data Exchange (ETDEWEB)

Positron annihilation lifetime spectroscopy was conducted for a synthetic saponite to investigate hydration and dehydration behaviour occurring in nanoscale interlayer spaces. Long positron lifetime of {approx} 24 ns was observed with the intensity of {approx} 8 % when the sample is evacuated at {approx} 10{sup -5} Torr. The radius of open nanospace evaluated from the positron lifetime is {approx} 10 A, which corresponds to the interlayer spaces of saponite. The open nanospace increases up to 13 % after baking at 423 K for 8 h under the vacuum. The present results imply that positron annihilation spectroscopy is powerful tool to investigate hydration and dehydration behavior through the local structural changes in the interlayer spaces of clay minerals.

Sato, K; Fujimoto, K; Nakata, M; Shikazono, N, E-mail: sato-k@u-gakugei.ac.jp

2010-11-15

153

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.; Portilla, M.

1991-01-01

154

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

UK PubMed Central (United Kingdom)

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.

Zingg A; Winnefeld F; Holzer L; Pakusch J; Becker S; Gauckler L

2008-07-01

155

Methane hydrate dissociation controlled by gas diffusion  

Energy Technology Data Exchange (ETDEWEB)

Given the importance of gas hydrates as a gas resource for the future, hydrate dissociation kinetics must be well understood for exploration purposes. In this study, the kinetic data of methane (CH{sub 4}) hydrate dissociation at various temperatures and pressures was measured using a sapphire cell apparatus. Constant dissociation pressure methods at above and below 0 degrees C were used to obtain the dissociation kinetics data for methane hydrate. The results indicate that the hydrate dissociation rate is controlled by intrinsic dissociation reaction, and is proprionate to the fugacity difference between the state of equilibrium and the operating state when the system temperature was higher than freezing. When the system temperature was below freezing, water generated from hydrate dissociation would quickly transform into ice at the surface of hydrate crystals. The gas released diffused from the hydrate and ice layer to the gas phase. The thickness of hydrate and ice mixture layer increased within the hydrate dissociation. The hydrate layer thickness was reduced as they hydrate continued to dissociate. The boundary of the hydrate dissociation process was viewed as a moving boundary. Experimental data was in good agreement with results obtained from newly developed kinetic models for hydrate dissociation.

Sun, C.Y.; Chen, G.J. [Petroleum Univ., Beijing (China). High Pressure Fluid Phase Behavior and Property Research Laboratory

2004-07-01

156

Adsorption of surfactants on two different hydrates.  

UK PubMed Central (United Kingdom)

The interaction between surfactants and hydrates provides insight into the role of surfactants in promoting hydrate formation. This work aims at understanding the adsorption behavior of sodium dodecyl sulfate (SDS) on cyclopentane (CP) hydrates and its derivative surfactant on tetrabutylammonium bromide (TBAB) hydrates. Cyclopentane (CP) is a hydrophobic former whereas tetrabutylammonium bromide (TBAB) is a salt that forms semiclathrate hydrates. The adsorption on these two hydrates was studied by zeta potential and pyrene fluorescence measurements. CP hydrates have a negative surface charge in the absence of SDS, and it decreases to a minimum as the SDS concentration increases from 0 to 0.17 mM. Then, it increases with further increased SDS concentration. The adsorption density of DS (-) on CP hydrates reaches a saturated value at 1.73 mM SDS. The micropolarity parameter of the TBAB hydrate/water interface starts to increase rapidly at 0.17 mM SDS and levels off at 1.73 mM SDS. The presence of Br (-) in TBAB hydrate suspensions could compete with TBADS (from association of DS (-) and TBA (+)) and DS (-) for the adsorption on the hydrate surface, but they have a much stronger affinity for the hydrates than does Br (-). From the fluorescence measurements, it was found that the micropolarity of the hydrate/water interface is mainly dependent on the polarity of hydrate formers.

Lo C; Zhang JS; Somasundaran P; Lu S; Couzis A; Lee JW

2008-11-01

157

Adsorption of surfactants on two different hydrates.  

Science.gov (United States)

The interaction between surfactants and hydrates provides insight into the role of surfactants in promoting hydrate formation. This work aims at understanding the adsorption behavior of sodium dodecyl sulfate (SDS) on cyclopentane (CP) hydrates and its derivative surfactant on tetrabutylammonium bromide (TBAB) hydrates. Cyclopentane (CP) is a hydrophobic former whereas tetrabutylammonium bromide (TBAB) is a salt that forms semiclathrate hydrates. The adsorption on these two hydrates was studied by zeta potential and pyrene fluorescence measurements. CP hydrates have a negative surface charge in the absence of SDS, and it decreases to a minimum as the SDS concentration increases from 0 to 0.17 mM. Then, it increases with further increased SDS concentration. The adsorption density of DS (-) on CP hydrates reaches a saturated value at 1.73 mM SDS. The micropolarity parameter of the TBAB hydrate/water interface starts to increase rapidly at 0.17 mM SDS and levels off at 1.73 mM SDS. The presence of Br (-) in TBAB hydrate suspensions could compete with TBADS (from association of DS (-) and TBA (+)) and DS (-) for the adsorption on the hydrate surface, but they have a much stronger affinity for the hydrates than does Br (-). From the fluorescence measurements, it was found that the micropolarity of the hydrate/water interface is mainly dependent on the polarity of hydrate formers. PMID:18947240

Lo, C; Zhang, J S; Somasundaran, P; Lu, S; Couzis, A; Lee, J W

2008-10-24

158

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 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.

1991-01-01

159

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

International Nuclear Information System (INIS)

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

1981-01-01

160

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

 
 
 
 
161

Indústria mineral  

Directory of Open Access Journals (Sweden)

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

Iran F. Machado

1998-01-01

162

Hydration of "nonfouling" functional groups.  

UK PubMed Central (United Kingdom)

The prevention of nonspecific protein adsorption to synthetic materials and devices presents a major design challenge in the biomedical community. While some chemical groups can resist nonspecific protein adsorption from simple solutions for limited contact times, there remains a need for new nonfouling functional groups and surface coatings that prevent protein adsorption from complex media like blood or in harsh environments like seawater. Recent studies of the molecular mechanisms of nonfouling surfaces have identified a strong correlation between surface hydration and resistance to nonspecific protein adsorption. In this work, we describe a simple experimental method for evaluating the intrinsic hydration capacity of model surface coating functional groups based on the partial molal volume at infinite dilution. In order to evaluate a range of hydration capacity and nonfouling performance, solutes were selected from three classes: ethylene glycols, sugar alcohols, and glycine analogues. The number of hydrating water molecules bound to a solute was estimated by comparing the molecular volume at infinite dilution to the solute van der Waals molecular volume. The number of water molecules associated with each solute was further validated by constant pressure and temperature molecular dynamics simulations. Finally, a size-normalized molecular volume was correlated to previously observed protein adsorption experiments to relate the intrinsic hydration capacity of functional groups to their known nonfouling abilities.

Hower JC; Bernards MT; Chen S; Tsao HK; Sheng YJ; Jiang S

2009-01-01

163

Adhesion of hydrated silicate films  

Energy Technology Data Exchange (ETDEWEB)

We used fracture mechanics test techniques to measure the adhesive bond energy formed between hydrated silica glass surfaces and silicate species deposited from solution. In the case of silicate surfaces hydrated in room temperature water vapor, intermolecular bonding between hydrated surfaces can be attributed to either hydrogen bonding interactions between adsorbed water molecules (0.15 Jm/sup 2/) or electrostatic bonds formed between adsorbed cations and anionic-nonbridging surface oxygen groups (2.0 Jm/sup 2/). The bonding interaction observed at room temperature depends upon the glass surface composition and the degree of surface hydration. When hydrated silicate solution species are added to the interface and heat treated, adhesion energies as large as the cohesive energy of silica glass can be obtained with heat treatments as low as 200/degree/C. The adhesion of the silicate interfacial film produced by the addition of solution species is greatest for silicate precursors showing a low degree of molecular crosslinking. In addition, the presence of alkali in the silicate solution greatly enhances interface adhesion for heat treatments below 200/degree/C. 9 refs., 10 figs.

Michalske, T.A.; Keefer, K.D.

1988-01-01

164

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

165

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

166

Mineral fibres and health  

International Nuclear Information System (INIS)

The use of inorganic fibrous materials is a comparatively new phenomenon and was uncommon before the Industrial Revolution. Humans evolved in a comparatively fibre-free environment and consequently never fully developed the defence mechanisms needed to deal with the consequences of inhaling fibres. However, the urban environment now has an airborne fibre concentration of around 1 f.l-1, which is a tenfold increase on the natural background. Any sample of ambient air collected indoors or outdoors will probably contain some mineral fibres, but there is little evidence that these pose any risk to human health. They come from asbestos used in brakes, glass and mineral wools used as insulation and fire proofing of buildings, gypsum from plaster and a variety of types from many sources. Few of these have the potential to do any harm. Asbestos is the only fibre of note but urban levels are insignificant compared to occupational exposures. When the health of cohorts occupationally exposed to the several types of asbestos is studied the problem can be put into perspective. Studies of workers in the chrysotile industry exposed to much higher dust levels than in a factory today show no excess lung cancer or mesothelioma. By comparison those living near crocidolite mines, let alone working in them, may develop asbestos-related disease. As always, dose is the critical factor. Chrysotile is cleared from the lungs very efficiently, only the amphiboles are well retained. The only real health problem comes from the earlier use of asbestos products that may now be old, friable and damaged and made from amphibole or mixed fibre. If though, these are still in good condition, they do not pose a health problem. Asbestos-related diseases are very rare in those not occupationally exposed. Where they exist exposure has nearly always been to crocidolite. (author)

2001-01-01

167

[Therapeutic agents for disorders of bone and calcium metabolism: Minodronic acid hydrate].  

UK PubMed Central (United Kingdom)

Minodronic acid hydrate is one of the new-generation bisphosphonates containing nitrogen. This drug has an inhibitory effect on bone resorption by suppressing the osteoclastic function, and it is being developed as a therapeutic drug of osteoporosis. In non-clinical study, the drug has an inhibitory effect on the decrease of the bone mineral density and the bone intensity in ovariectomized rat osteoporosis models. The one of two Phase III studies, conducted so far, indicated that minodronic acid hydrate, administered once daily for 104 weeks, reduced the risk of vertebral fracture compared to placebo in postmenopausal Japanese women with osteoporosis. The other study conducted that minodronic acid hydrate increases the bone mineral density at least equivalent to that of alendronate for 48 weeks. The safety analysis in the latest study revealed that the adverse events of minodoronic acid hydrate have no statistically significant differences from the placebo group. We expect that minodronic acid hydrate will be used for a number of patients with osteoporosis as a potent and safe domestically created bisphosphonate in the near future.

Miki T; Minamide T

2007-01-01

168

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

169

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

170

Hydrated interfacial ions and electrons.  

UK PubMed Central (United Kingdom)

Charged particles such as hydrated ions and transient hydrated electrons, the simplest anionic reducing agents in water, and the special hydronium and hydroxide ions at water interfaces play an important role in many fields of science, such as atmospheric chemistry, radiation chemistry, and biology, as well as biochemistry. This article focuses on these species near hydrophobic interfaces of water, such as the air or vacuum interface of water or water protein/membrane interfaces. Ions at interfaces as well as solvated electrons have been reviewed frequently during the past decade. Although all species have been known for some time with seemingly familiar features, recently the picture in all cases became increasingly diffuse rather than clearer. The current account gives a critical state-of-the art overview of what is known and what remains to be understood and investigated about hydrated interfacial ions and electrons.

Abel B

2013-01-01

171

Hydrating foodstuffs with a premix  

UK PubMed Central (United Kingdom)

A substance for use in, and a method for, hydrating dry or dehydrated foodstuffs. The substance comprises a premix including water and other ingredients which is mixed in a substantially homogenous condition, with the of dry or dehydrated foodstuff to hydrate the foodstuff for consumption. The substance may include a stabilizer to preserve homogeneity of the ingredients. For the production of a Spanish paella, the substance could comprise onion, garlic, peppers, broth, saffron, tumeric, salt, pepper, herbs and spices, paprika, lemon juice and/or vinegar and tomato. The substance may be mixed with rice and cooked. The substance may be in the form of a concentrate which requires further water in order to hydrate the foodstuff to the desired condition for consumption.

MUSSAWIR-KEY RUTH HELENE

172

Spin depolarization in muonium by hydrated electrons  

International Nuclear Information System (INIS)

[en] The missing fraction of muon polarization in water is shown to originate from encounters between muonium and hydrated electrons. This takes place at about 1 ns after the primary events in which muonium and hydrated electrons are born

1982-01-01

173

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

174

Rocks and Minerals  

Science.gov (United States)

Rock Cycle Mineralogy 4 Kids Mineralogy 4 kids : rockin Internet site : the best place to learn about rocks and minerals Rock Cycle Map Rocks and Minerals Rocks and Minerals Pictures Rocks and Minerals Slide Show Rocks and Minerals Slide Show Earth Science Earth Science Uses for Minerals Metamorphic Rock Forming Sedimentary Rocks Observation ...

Richrigby

2010-02-23

175

Nature of hydrated sodium polyvanadates  

International Nuclear Information System (INIS)

[en] Using the methods of IR spectroscopy, EPR and NMR hydrated hexa- and dodecavanadates of sodium and products of their dehydration are studied. Geometric parameters of water molecules are determined. It is established that the compounds studied contain two types of water molecules, which condition the stage character of dehydration. Complete dehydration of dodecavanadate (t > 280 deg) results in irreversible structural changes with the formation of bronze Na2V6O15 (?). In hexavanadate after removal of zeolite water hydrated bronze is formed. Further rebuilding is accompanied by formation of oxide vanadium bronze Nasub(2+2x)Vsub(6)Osub(16)

1982-01-01

176

Nature of hydrated sodium polyvanadates  

Energy Technology Data Exchange (ETDEWEB)

Using the methods of IR spectroscopy, EPR and NMR hydrated hexa- and dodecavanadates of sodium and products of their dehydration are studied. Geometric parameters of water molecules are determined. It is established that the compounds studied contain two types of water molecules, which condition the stage character of dehydration. Complete dehydration of dodecavanadate (t > 280 deg) results in irreversible structural changes with the formation of bronze Na/sub 2/V/sub 6/O/sub 15/ (..beta..). In hexavanadate after removal of zeolite water hydrated bronze is formed. Further rebuilding is accompanied by formation of oxide vanadium bronze Nasub(2+2x)Vsub(6)Osub(16).

Koryakova, O.V.; Perelyaeva, L.A.; Belyakov, Yu.M.; Zabolotskaya, E.V.; Pletnev, R.N.; Ivakin, A.A.

1982-03-01

177

[Hypodermoclysis hydration in the elderly].  

UK PubMed Central (United Kingdom)

Hydration with hypodermoclysis in elderly patients. Hypodermoclysis is a technique which consists in the administration of fluids into the subcutaneous tissue for the treatment of mild to moderate dehydration. The article starts from the case of a 74 year old man that, after a stroke, was unable to eat or drink, and was then hydrated with continuous hypodermoclysis for 45 days, obtaining a recovery of the clinical and psychological conditions. An update of the available knowledge on hypodermoclisis, together with some comments on the clinical case are presented.

Brugnolli A; Bevilacqua A; Clodig M; Danielis M

2012-07-01

178

[Hypodermoclysis hydration in the elderly].  

Science.gov (United States)

Hydration with hypodermoclysis in elderly patients. Hypodermoclysis is a technique which consists in the administration of fluids into the subcutaneous tissue for the treatment of mild to moderate dehydration. The article starts from the case of a 74 year old man that, after a stroke, was unable to eat or drink, and was then hydrated with continuous hypodermoclysis for 45 days, obtaining a recovery of the clinical and psychological conditions. An update of the available knowledge on hypodermoclisis, together with some comments on the clinical case are presented. PMID:23164967

Brugnolli, Anna; Bevilacqua, Anita; Clodig, Majda; Danielis, Matteo

179

An experimental investigation on THF hydrate rystallization  

Energy Technology Data Exchange (ETDEWEB)

The metastable zone of THF hydrate crystallization was investigated. It was found that formation of THF hydrate was possible in between solution concentrations of 9 and 46 percent by weight. Induction time for nucleation was also determined. The results indicate that the lowest induction time for nucleation corresponded to hydrate crystallization from a solution with a THF concentration of 19 percent. This solution concentration matches with the stoichiometric percentage of THF in the crystalline hydrate. (Author)

Ganji, H.; Manteghian, M.; Sadaghiani Zadeh, K.; Torabi, F.

2005-07-01

180

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

CERN Multimedia

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

 
 
 
 
181

Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean  

Science.gov (United States)

The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.

Himmler, Tobias; Haley, Brian A.; Torres, Marta E.; Klinkhammer, Gary P.; Bohrmann, Gerhard; Peckmann, Jörn

2013-07-01

182

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

183

Mineral-mineral associations characterized by QEMSCAN  

Energy Technology Data Exchange (ETDEWEB)

Mineral matter in coals contributes to operational and environmental problems associated with coal utilization processes such as pulverized coal combustion. With the aid of QEMSCAN technology, mineral matter in a suite of Australian pulverized coals has been measured in Particle Mineralogical Analysis (PMA) mode. In this paper, information on mineral-mineral associations for these coals has been presented for first time. Statistical results based on pixel-by-pixel mode show that usually oxides associate with silicates; silicates associate with silicates; carbonates associate with carbonates. In addition, Ca-bearing minerals prefer to associate with other Ca-bearing minerals; Fe-bearing minerals prefer to associate with other Fe-bearing minerals. The results can be explained by geological environment and processes in which Australian coals and mineral matter in coals formed. For combustion engineering practice, a new definition of mineral-mineral association has been adopted to describe how mineral grains associate with each other inside a single coal particle. The mineral-mineral association for included mineral grains was used as an input into an ash formation model at two limiting extremes, i.e. (A) one coal particle to one ash particle and (B) one mineral grain to one ash particle. Size and chemistry of ash particles were predicted and compared by two ash formation models. 6 refs., 3 figs., 1 tab.

Yinghui Liu; Raj Gupta; Terry Wall; Alan Butcher; Paul Gottlieb; David French [University of Newcastle, Callaghan, NSW (Australia). Cooperative Research Centre for Coal in Sustainable Development, Department of Chemical Engineering

2005-07-01

184

Mineral transportation  

Energy Technology Data Exchange (ETDEWEB)

Westbound movements of bulk coal will increase to 81 million tonnes in 1985 from 44.6 million t in 1980 and 49.3 percent of this predicted amount will be coal with grain, potash and sulphur accounting for the remainder. The rail sector and the Crow's Nest problem, Port of Vancouver, Prince Rupert, White Pass and Yukon Railway, St Lawrence Seaway, east coast potash terminal, Arctic shipping, and international shipping are discussed as to background and current events that concern the mineral industry.

Bokovay, G.

1982-02-01

185

Thermal conductivity of tetrahydrofuran hydrate  

CERN Multimedia

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; Korolyuk, O A; Gorodilov, B Y; Romantsovaa, O O

2004-01-01

186

Bitumen Aging and Hydrated Lime.  

Science.gov (United States)

Since the beginning of the 1970s, hopes have been that hydrated lime, beside being a useful antistripping agent, also might work as an inhibitor of bitumen hardening. These expectations appeared to be supported by the results of several laboratory investi...

L. S. Johansson

1998-01-01

187

Physical properties of gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are naturally occurring, solid crystalline compounds (clathrates) that encapsulate gas molecules inside the lattices of hydrogen bonded water molecules within a specific temperature-pressure stability zone. Estimates of the total quantity of available methane gas in natural occurring hydrates are based on twice the energy content of known conventional fossil fuels reservoirs. Accurate and reliable in-situ quantification techniques are essential in determining the economic viability of this potential energy yield, which is dependent upon several factors such as sensitivity of the temperature-pressure stability zone, sediment type, porosity, permeability, concentration/abundance of free gas, spatial distribution in pore spaces, specific cage occupancy, and the influence of inhibitors. Various techniques like acoustic P and S waves, time domain reflectometry, and electrical resistance have been used to analyze the quantity and spatial distribution of the gas hydrate samples. These techniques were reviewed and the results obtained in the course of gas hydrate research were presented. 34 refs., 8 figs.

Kliner, J.T.R.; Grozic, J.L.H. [Calgary Univ., AB (Canada)

2003-07-01

188

Hydration rind dates rhyolite flows.  

UK PubMed Central (United Kingdom)

Hydration of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago.

Friedman I

1968-02-01

189

Gas hydrate reservoir characteristics and economics  

Energy Technology Data Exchange (ETDEWEB)

The primary objective of the DOE-funded USGS Gas Hydrate Program is to assess the production characteristics and economic potential of gas hydrates in northern Alaska. The objectives of this project for FY-1992 will include the following: (1) Utilize industry seismic data to assess the distribution of gas hydrates within the nearshore Alaskan continental shelf between Harrison Bay and Prudhoe Bay; (2) Further characterize and quantify the well-log characteristics of gas hydrates; and (3) Establish gas monitoring stations over the Eileen fault zone in northern Alaska, which will be used to measure gas flux from destabilized hydrates.

Collett, T.S.; Bird, K.J.; Burruss, R.C.; Lee, Myung W.

1992-06-01

190

Gas hydrate reservoir characteristics and economics  

Energy Technology Data Exchange (ETDEWEB)

The primary objective of the DOE-funded USGS Gas Hydrate Program is to assess the production characteristics and economic potential of gas hydrates in northern Alaska. The objectives of this project for FY-1992 will include the following: (1) Utilize industry seismic data to assess the distribution of gas hydrates within the nearshore Alaskan continental shelf between Harrison Bay and Prudhoe Bay; (2) Further characterize and quantify the well-log characteristics of gas hydrates; and (3) Establish gas monitoring stations over the Eileen fault zone in northern Alaska, which will be used to measure gas flux from destabilized hydrates.

Collett, T.S.; Bird, K.J.; Burruss, R.C.; Lee, Myung W.

1992-01-01

191

Hydrated Silica at Mawrth Vallis and Implications for Past Environment  

Science.gov (United States)

Hydrated silica has been identified in many outcrops in the Mawrth Vallis region [1-3] often mixed with Al-bearing phyllosilicates such as kaolinite and montmorillonite. To determine which form of hydrated silica could be mixed with the Al-phyllosilicates at Mawrth Vallis, spectra of intimate mineral mixtures were measured in the lab and compared to CRISM spectra (figure 1). The mixtures considered were: kaolinite-opal-A, kaolinite-montmorillonite, montmorillonite-obsidian, montmorillonite-hydrated silica (opal), and glass-illite-smectite. The best spectral matches with Martian data from our lab experiments are mixtures of montmorillonite and obsidian having 20 to 50 % montmorillonite or mixtures of kaolinite and montmorillonite with 25 to 50 % kaolinite. The spectra of clay mixtures with opal and of hydrothermally altered glass-illite-smectite did not represent as well the Martian spectra observed in this region. This suggests that a cryptocrystalline (obsidian) or crystalline form of hydrated silica is present at Mawrth Vallis rather than an amorphous form (opal-A) which has been identified elsewhere on Mars [e.g. 4]. References: [1] Bishop, J. L. et al. (2008) Science, 321, 830-833. [2] McKeown, N. K. et al. (2009) JGR- Planets, 114, E00D10. [3] Noe Dobrea, E. Z. et al. (2010) JGR- Planets, 115, E00D19. [4] Milliken, R. E. et al. (2008) Geology, 36, 847-850. Figure 1 (left) Spectra of montmorillonite-obsidian mixtures compared to CRISM spectra from FRT0000848D. (right) Spectra of kaolinite-montmorillonite and kaolinite-SiOH (opal-A) mixtures compared to CRISM spectra from HRL000043EC and FRT0000848D.

McKeown, N. K.; Bishop, J. L.; Cuadros, J.; Hillier, S.; Parente, M.

2010-12-01

192

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 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)

2005-01-01

193

Progress in understanding the structure and thermodynamics of calcium silicate hydrates  

International Nuclear Information System (INIS)

Large quantities of cementitious materials may be used in constructing a potential nuclear-waste repository. A program has been designed to support the prediction of cement degradation and the chemistry of water in contact with cement, over extended periods of time (e.g., 10,000 y). This multidisciplinary experimental and computer modeling investigation is intended to characterize the structural and thermodynamic properties of crystalline phases found in cement at elevated temperatures. Many of these crystalline phases may be hydrated. The hydration state of these phases must be known to the interpret experimentally obtained thermodynamic data, to evaluate the stability of hydrated phases, and to estimate long-term water availability, such as would be required for prediction of the radioactive-waste repository's lifetime. The parts of the program associated with assessing and predicting dehydration/rehydration behavior are described in this paper: (1) identification of phases present in standardized grout mixtures exposed to elevated temperatures; (2) mechanistic and thermodynamic analysis of the hydration/dehydration behavior of hydrated calcium silicates as a function of temperature, pressure, and relative humidity; and (3) measurements of thermodynamic data for hydrated calcium silicates.

1994-01-01

194

Mineral rights  

Energy Technology Data Exchange (ETDEWEB)

Three major legislative developments in Louisiana affect mineral rights in the state. Act 345 amends the Revised Statutes to place a risk charge on owners of operating interests who are unwilling to commit funds to the drilling of a well on land included in a unit. Act 768 redefines pool for purposes of establishing units, and Act 559 requires notification by a lessee within 90 days of ceasing production. A review of pertinent case law affecting the oil and gas industry describes cases dealing with leasing, royalty contracts, mortgage foreclosures, and conservation. The author notes that the January 1, 1985 deregulation of a considerable portion of the state's natural gas will have great importance to the state because of slipping prices. One positive sign is the increase in operating drilling rigs from 268 to 314 during the past year.

Martin, P.H.

1984-11-01

195

Joint seismic and electrical measurements of gas hydrates in continental margin sediments  

Energy Technology Data Exchange (ETDEWEB)

The ever improving sophistication of marine seismic methods, coupled with recently developed active source electromagnetic methods, offer a pragmatic way of quantifying marine gas hydrates in situ. The aim of this work is to develop theoretical models that describe the seismic velocity and electrical resistivity of hydrate-bearing marine sediments for use in marine seismic/electrical data inversion schemes. An elastic effective medium technique was chosen that uses a combination of the self-consistent approximation (SCA) and the differential effective medium theory (DEM), linked through the probability of interconnection of the fluid phase. This approach was combined with an electrical effective medium model also incorporating the probability of interconnection, as well as the microstructure and relative proportions of each phase (mineral, hydrate, fluid). A two-phase version of this model was tested against laboratory ultrasonic P-wave velocity and electrical resistivity measurements on artificial sediment specimens created. (Author)

Ellis, Michelle H.; Minshull, Timothy A.; Best, Angus I.; Sinha, Martin C.; Sothcott, Jeremy

2005-07-01

196

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

International Nuclear Information System (INIS)

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

2003-01-01

197

Gas hydrates in drilling operations. Final report  

Energy Technology Data Exchange (ETDEWEB)

Hydrates are solid compounds of natural gas and water. They can exist at temperatures far above the freezing point of water at elevated pressures. Although more widely recognised as a problem in oil and gas production, the possibility of encountering hydrates during drilling or well control operations is well documented. There is an increasing level of interest in exploration in deep water areas west of Shetland. With water depths of 1000m or more and seabed temperatures near 0{sup o}C the likelihood of hydrate formation is significantly higher than in other parts of the UKCS or in the Gulf of Mexico where serious hydrate problems during well control operations have been reported. This report reviews the current state of knowledge of hydrates in drilling operations. It includes a brief summary of hydrate modelling, a review of the published literature and information contributed by operating companies. The principal conclusions are that hydrates are generally appreciated to be a potential hazard in drilling but, to date, no cases of hydrate problems have been reported by operators drilling in deep water on the UKCS. There is a sizeable literature that contains practical guidelines for dealing with hydrates in drilling. Although there are reliable data and models for defining the ranges of pressure and temperature where hydrates could form, there is a need for more data and new models to characterise and predict the rate of formation. This is a particularly challenging problem with drilling fluids. (Author)

NONE

1996-10-01

198

Hydration management at the end of life.  

Science.gov (United States)

The management of parenteral hydration at the end of life remains controversial. The debate centers on whether and/or how often patients should be hydrated, the volume of hydration received, and the benefit verses side effects of parenteral hydration. In order to clarify the routine practice of physicians involved in the end-of-life care in Edmonton, Alberta, Canada, we investigated the routine management of hydration by attending physicians caring for patients dying in a palliative care unit (PCU) at Norwood Capital Care, and in acute care wards at the Royal Alexandra Hospital (RAH) both while receiving and while not receiving consult advice from the Palliative Care Program. We conducted a retrospective chart review of 50 consecutive patients who died in each of the 3 sites included in the study. Data from the last 7 days prior to and including the date of death (day 0) was recorded. The majority of patients at all sites received hydration. The volume of hydration ordered in the Norwood PCU site was significantly different compared to both RAH groups on all days studied (p hypodermoclysis (HDC) was ordered; for nearly all of the hydrated patients in the RAH acute care group, intravenous (IV) hydration was ordered; and for approximately one third of the hydrated RAH palliative care consult group HDC was ordered, and for the remainder IV hydration was ordered. The RAH acute care group represented the largest percentage of hydrated patients receiving diuretics while the Norwood hospice site represented the lowest. The data raise the possibility that more patients in the RAH acute care group were overhydrated and may have developed symptoms such as edema, ascites, and respiratory distress. This study suggests that hydration at the end of life is managed differently in different settings of care and highlights areas for education to improve management. PMID:15130203

Lanuke, Kathryn; Fainsinger, Robin L; DeMoissac, Donna

2004-04-01

199

Dipolar response of hydrated proteins  

CERN Multimedia

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

200

Dynamics of hydrated starch saccharides  

Energy Technology Data Exchange (ETDEWEB)

We report here elastic neutron scattering data on glucose and on two of its polymeric forms: amylose and amylopectin. We have covered the hydration range from the dry state to about 0.6 g water/g dry saccharide. The data indicate, in all the analysed systems, the presence of a dynamic glass-like transition similar to that observed in hydrated proteins. The fact that this feature is observed also in a relatively small molecule like glucose confirms the hypothesis already put forward by other authors, that this transition in biomolecular species is essentially triggered and driven by the interaction of the macromolecule with the network of fluctuating H-bond of the solvent.

Di Bari, M.; Deriu, A.; Albanese, G.; Cavatorta, F

2003-08-01

 
 
 
 
201

Ocean circulation promotes methane release from gas hydrate outcrops at the NEPTUNE Canada Barkley Canyon node  

Science.gov (United States)

The NEPTUNE Canada cabled observatory network enables non-destructive, controlled experiments and time-series observations with mobile robots on gas hydrates and benthic community structure on a small plateau of about 1 km2 at a water depth of 870 m in Barkley Canyon, about 100 km offshore Vancouver Island, British Columbia. A mobile Internet operated vehicle was used as an instrument platform to monitor and study up to 2000 m2 of sediment surface in real-time. In 2010 the first mission of the robot was to investigate the importance of oscillatory deep ocean currents on methane release at continental margins. Previously, other experimental studies have indicated that methane release from gas hydrate outcrops is diffusion-controlled and should be much higher than seepage from buried hydrate in semipermeable sediments. Our results show that periods of enhanced bottom currents associated with diurnal shelf waves, internal semidiurnal tides, and also wind-generated near-inertial motions can modulate methane seepage. Flow dependent destruction of gas hydrates within the hydrate stability field is possible from enhanced bottom currents when hydrates are not covered by either seafloor biota or sediments. The calculated seepage varied between 40-400 ?mol CH4 m-2 s-1. This is 1-3 orders of magnitude higher than dissolution rates of buried hydrates through permeable sediments and well within the experimentally derived range for exposed gas hydrates under different hydrodynamic boundary conditions. We conclude that submarine canyons which display high hydrodynamic activity can become key areas of enhanced seepage as a result of emerging weather patterns due to climate change.

Thomsen, Laurenz; Barnes, Christopher; Best, Mairi; Chapman, Ross; Pirenne, Benoît; Thomson, Richard; Vogt, Joachim

2012-08-01

202

Multivitamin/Mineral Supplements  

Science.gov (United States)

What are multivitamin/mineral (MVM) dietary supplements? Multivitamin/mineral (MVM) supplements contain a combination of vitamins and minerals, and sometimes other ingredients as well. They go by many names, ...

203

Zaccai neutron resilience and site-specific hydration dynamics in a globular protein.  

UK PubMed Central (United Kingdom)

A discussion is presented of contributions of the Zaccai group to the understanding of flexibility in biological macromolecules using dynamic neutron scattering. The concept of resilience as introduced by Zaccai is discussed and investigated using molecular dynamics simulation on camphor-bound cytochrome P450. The resilience of hydrophilic residues is found to be more strongly affected by hydration than that of hydrophobic counterparts. The hydration-induced softening of protein propagates from the surface into the dry core. Moreover, buried hydrophilic residues behave more like those exposed on the protein surface, and are different from their hydrophobic counterparts.

Miao Y; Hong L; Yi Z; Smith JC

2013-07-01

204

Synthesis of hydrated lutetium carbonate  

Energy Technology Data Exchange (ETDEWEB)

Crystalline lutetium carbonate was synthesized for the corresponding chloride using ammonium bicarbonate as precipitant. The chemical analyses suggest that the synthesized lutetium carbonate is a hydrated basic carbonate or oxycarbonate. The X-ray powder diffraction data are presented. The IR data for the compound show the presence of two different carbonate groups. There is no stable intermediate carbonate in the process of thermal decomposition of the lutetium carbonate. (au) 15 refs.

Song Liu [South China Univ. of Technology, Dept. of Applied Chemistry, Guangdong (China); Rong-jun Ma [Changsha Research Institute of Minig and Metallurgy, Hunan (China)

1997-09-01

205

Shear dynamics of hydration layers.  

UK PubMed Central (United Kingdom)

Molecular dynamics (MD) simulations have been performed to investigate the shear dynamics of hydration layers of the thickness of D=0.61-2.44 nm confined between two mica surfaces. Emphases are placed on the external shear response and internal relaxation properties of aqueous films. For D=0.92-2.44 nm 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=0.61 nm) [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 0.017 ms (10(-5) s). 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< or =0.6+/-0.3 nm 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 Y; Cummings PT

2006-09-01

206

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=0.61-2.44 nm confined between two mica surfaces. Emphases are placed on the external shear response and internal relaxation properties of aqueous films. For D=0.92-2.44 nm 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=0.61 nm) [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 0.017 ms (10-5 s). 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+/-0.3 nm 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

207

South Africa's mineral industry  

International Nuclear Information System (INIS)

[en] 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

1985-01-01

208

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

209

Testing evidence of recent hydration state change in sulfates on Mars  

Science.gov (United States)

The East Candor Interior Layered Deposit (ILD) has signatures of mono- and polyhydrated sulfate in alternating layers that give insight into the processes which formed these layered deposits and on the environmental conditions acting on them since then. We use orbital data to explore multiple hypotheses for how these deposits formed: (1) sulfate-bearing ILDs experience hydration changes on seasonal to a few years timescales under current Mars environmental conditions; (2) the deposits experience hydration under recent Mars conditions but require the wetter climate of high obliquity; and (3) the kieserite could be an original or diagenetic part of a complex evaporite mineral assemblage. Modeled climatology shows recent Mars environmental conditions might pass between multiple sulfate fields. However, comparison of Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) and Compact Reconnaissance Imaging Spectrometer (CRISM) observations of the same ILD do not show changes in hydration over 2 Mars years. Low temperatures might slow the kinetics of that transition; it is likely that more clement conditions during periods of high obliquity are needed to overcome mineral metastability and hydrate kieserite-bearing deposits. We find the alternate model, that the deposit is a cyclic evaporite sequence of mono- and polyhydrated sulfates, also plausible but with an unexplained dearth of Fe sulfates.

Roach, L. H.; Mustard, J. F.; Murchie, S. L.; Bibring, J.-P.; Forget, F.; Lewis, K. W.; Aharonson, O.; Vincendon, M.; Bishop, J. L.

2009-04-01

210

Hydrogen (H2) Storage in Clathrate Hydrates  

CERN Multimedia

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

211

Unique purified hydrated-gelatin diet for feeding dietary fiber to Wistar rats.  

UK PubMed Central (United Kingdom)

A purified hydrated gelatin diet was developed for feeding dietary fibers to Wistar rats. A dry fiber mix was prepared that consisted of 54.91 dextrose, 13.80 casein, 2.97 AIN mineral mix, 1.28 AIN vitamin mix, 0.17 dl-methionine, 6.80 lard and 5.10 gelatin (g/100g total dry feed). Either cellulose, hemicellulose, lignin, or pectin (15 g/100 g total dry feed) was added to the hydrated dry fiber mix and blended until complete distribution and hydration of the fiber was achieved. After gelling, these hydrated diets were stable for up to 24 hours in environmental conditions commonly encountered in animal facilities. Gel weep was minimal thus permitting feed consumption to be monitored conveniently by weighing the residue in the feeders. In situ examination of stomach contents after feeding such hydrated diets to rats indicated that the gelatin gel was readily degraded and did not confound gel formation by fiber itself. Feed efficiency values (g gain/100 kcal digestible energy) for these diets following a 26-day feeding trial were as follows: no fiber, 6.21; cellulose, 6.38; hemicellulose, 6.23; lignin, 6.52; and pectin, 5.53.

deBethizy JD; Street JC

1984-02-01

212

Empirical force fields for complex hydrated calcio-silicate layered materials.  

UK PubMed Central (United Kingdom)

The use of empirical force fields is now a standard approach in predicting the properties of hydrated oxides which are omnipresent in both natural and engineering applications. Transferability of force fields to analogous hydrated oxides without rigorous investigations may result in misleading property predictions. Herein, we focus on two common empirical force fields, the simple point charge ClayFF potential and the core-shell potential to study tobermorite minerals, the most prominent family of Calcium-Silicate-Hydrates that are complex hydrated oxides. We benchmark the predictive capabilities of these force fields against first principles results. While the structural information seem to be in close agreement with DFT results, we find that for higher order properties such as elastic constants, the core-shell potential quantitatively improves upon the simple point charge model, and shows a larger degree of transferability to complex materials. In return, to remedy the deficiencies of the simple point charge potential for hydrated calcio-silicates, we suggest using both structural data and elasticity data for potential calibration, a new force field potential, CSH-FF. This re-parameterized version of ClayFF is then applied to simulating an atomistic model of cement (Pellenq et al., PNAS, 2009). We demonstrate that this force field improves the predictive capabilities of ClayFF, being considerably less computational intensive than the core-shell model.

Shahsavari R; Pellenq RJ; Ulm FJ

2011-01-01

213

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

UK PubMed Central (United Kingdom)

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.

Kaasik A; Vohla C; Mõtlep R; Mander U; Kirsimäe K

2008-02-01

214

Adhesive properties of gas hydrates and ice  

Energy Technology Data Exchange (ETDEWEB)

Results of experiments on the temperature dependence of ice and hydrate adhesion strength were discussed. Samples made of steel, duralumin and polytetrafluoroethylene were use as substrate for the study involving hydrates of natural gas and tetrahydrofuran. Results showed that the hydrate adhesion strength was much higher for hydrophilic surfaces than for hydrophobic ones. Adhesion contact formation for ice also depends on surface wettability. 9 refs., 2 figs.

Bondarev, E. A.; Groisman, A. G.; Savvin, A. Z.

1996-10-01

215

Seismic Characterization Of Methane Hydrate Structures  

UK PubMed Central (United Kingdom)

Bottom simulating reflectors (BSR) seem to be associated with the base of the stability zoneof methane hydrates. These methane hydrates represent a potential future energy resourceand might have a strong "greenhouse" effect on global climate. In this dissertation I integrateseismic and rock-physics to analyze seismic data from the Blake Outer Ridge, offshore Florida.I infer the cause of the BSR visible in the data and estimate the amount of hydrate present inthe sediment structure.

Christine Ecker; Jon F. Claerbout

216

Why not use methanol for hydrate control  

Energy Technology Data Exchange (ETDEWEB)

Methanol, instead of solid bed dehydration, is suggested to avoid hydrate formation in turboexpander plants. Hydrates (crystals resembling wet snow) plug pipeworks and valves. Methanol used as an antifreeze to depress the freezing point of the water is studied. Alcohol to depress the formation temperature of hydrate in a gas is also studied. Confusion between the two methods is clarified. Comparison between methanol injection and solid bed dehydration is made; methanol has lower costs.

Nielsen, R.B.; Bucklin, R.W.

1983-04-01

217

Femtosecond Solvation Dynamics of the Hydrated Electron  

International Nuclear Information System (INIS)

Femtosecond pump-probe spectroscopy of the equilibrated hydrated electron has been recorded with 35fs resolution, revealing unprecedented transient features on the 30 endash 80fs time scales that have been assigned to inertial solvation dynamics of the hydrated electron. These data allow for a rigorous experimental evaluation of the recently published nonadiabatic quantum molecular dynamics simulations of the adiabatic and nonadiabatic dynamics of the hydrated electron. copyright 1998 The American Physical Society.

1998-01-01

218

Femtosecond Solvation Dynamics of the Hydrated Electron  

Science.gov (United States)

Femtosecond pump-probe spectroscopy of the equilibrated hydrated electron has been recorded with 35 fs resolution, revealing unprecedented transient features on the 30-80 fs time scales that have been assigned to inertial solvation dynamics of the hydrated electron. These data allow for a rigorous experimental evaluation of the recently published nonadiabatic quantum molecular dynamics simulations of the adiabatic and nonadiabatic dynamics of the hydrated electron.

Silva, Carlos; Walhout, Peter K.; Yokoyama, Kazushige; Barbara, Paul F.

1998-02-01

219

Physicochemical properties of ionic clathrate hydrates.  

UK PubMed Central (United Kingdom)

Ionic clathrate hydrates are known to be formed by the enclathration of hydrophobic cations or anions into confined cages and the incorporation of counterions into the water framework. As the ionic clathrate hydrates are considered for their potential applicability in various fields, including those that involve solid electrolytes, gas separation, and gas storage, numerous studies of the ionic clathrate hydrates have been reported. This review concentrates on the physicochemical properties of the ionic clathrate hydrates and the notable characteristics of these materials regarding their potential application are addressed.

Shin K; Cha JH; Seo Y; Lee H

2010-01-01

220

Physicochemical properties of ionic clathrate hydrates.  

Science.gov (United States)

Ionic clathrate hydrates are known to be formed by the enclathration of hydrophobic cations or anions into confined cages and the incorporation of counterions into the water framework. As the ionic clathrate hydrates are considered for their potential applicability in various fields, including those that involve solid electrolytes, gas separation, and gas storage, numerous studies of the ionic clathrate hydrates have been reported. This review concentrates on the physicochemical properties of the ionic clathrate hydrates and the notable characteristics of these materials regarding their potential application are addressed. PMID:19760703

Shin, Kyuchul; Cha, Jong-Ho; Seo, Yongwon; Lee, Huen

2010-01-01

 
 
 
 
221

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.

Tsutomu Uchida; Toshiki Shiga; Masafumi Nagayama; Kazutoshi Gohara

2010-01-01

222

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

2007-01-01

223

METHOD OF HYDRATION OF VEGETABLE OIL  

UK PubMed Central (United Kingdom)

FIELD: foodstuffs. ^ SUBSTANCE: proposed method includes mixing unrefined oil with hydrating agent, holding the received mix, separating phospholipide emulsion from hydrated oil. As a hydrating agent, a mix of proteins produced from the cereals, phospholipides produced from vegetable oil and water, at the weight ratio of (1:2:100) to (1:3:100), respectively, at the amount of 1 to 4% of the weight of un refined vegetable oil. ^ EFFECT: high-quality hydrated oils with reduced content of phospholipide and low colour and acid numbers. ^ 2 tbl, 2 ex

MARTOVSHCHUK VALERIJ IVANOVICH; BEREZOVSKAJA OLESJA MIKHAJLOVN; GJULUSHANJAN ASMIK PETROVNA; MARTOVSHCHUK EVGENIJA VLADIMIROVNA; ILLARIONOVA VERA VLADIMIROVNA; ZABOLOTNIJ ALEKSEJ VIKTOROVICH; UL JANOVA OL GA VLADIMIROVNA; NIKOGDA VADIM OLEGOVICH

224

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

225

Hydration: issues for the 21st century.  

UK PubMed Central (United Kingdom)

Historically, hydration research reflected critical issues of the day. War, illness, surviving a shipwreck or time in the dessert, supplying fall-out shelters, and space exploration drove hydration research in the first half of the 20th century. The fitness revolution of the 1970s spurred research on dehydration in physically active people and athletes. The 1990s introduced the "fluid/disease relationship." What will be the driving force behind hydration research in the 21st century? Where are the gaps in our knowledge? This review provides an overview of issues pertinent to determining future directions in hydration research.

Grandjean AC; Reimers KJ; Buyckx ME

2003-08-01

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

Super-hydrated zeolites: pressure-induced hydration in natrolites.  

UK PubMed Central (United Kingdom)

High-pressure synchrotron X-ray powder diffraction studies of a series of alkali-metal-exchanged natrolites, A16Al16Si24O80·nH2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure-induced hydration (PIH) is inversely proportional to the non-framework cation radius. The expansion of the unit-cell volume through PIH is as large as 20.6% in Li-natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3% in Na-, K-, and Rb-natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non-framework cation radius up to 2.0 GPa in Rb-natrolite. In Cs-natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8% contracted unit cell and different cation-water configuration in the pores. In K-natrolite, the elliptical channel undergoes a unique overturn upon the formation of super-hydrated natrolite K16Al16Si24O80·32H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super-hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water.

Seoung D; Lee Y; Kao CC; Vogt T; Lee Y

2013-08-01

228

Super-hydrated zeolites: pressure-induced hydration in natrolites.  

Science.gov (United States)

High-pressure synchrotron X-ray powder diffraction studies of a series of alkali-metal-exchanged natrolites, A16Al16Si24O80·nH2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure-induced hydration (PIH) is inversely proportional to the non-framework cation radius. The expansion of the unit-cell volume through PIH is as large as 20.6% in Li-natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3% in Na-, K-, and Rb-natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non-framework cation radius up to 2.0 GPa in Rb-natrolite. In Cs-natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8% contracted unit cell and different cation-water configuration in the pores. In K-natrolite, the elliptical channel undergoes a unique overturn upon the formation of super-hydrated natrolite K16Al16Si24O80·32H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super-hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water. PMID:23852613

Seoung, Donghoon; Lee, Yongmoon; Kao, Chi-Chang; Vogt, Thomas; Lee, Yongjae

2013-07-12

229

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

Energy Technology Data Exchange (ETDEWEB)

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 prove useful to apply more than one production. (author)

Demirbas, Ayhan [Sirnak University, Dean of Engineering Faculty, Sirnak (Turkey)

2010-07-15

230

Effects of alkalies on hydration of {beta}-dicalcium silicate and its resultant hydrates  

Energy Technology Data Exchange (ETDEWEB)

{beta}-dicalcium silicate was synthesized and hydrated with/without alkalies at different temperatures. Alkalies accelerated the hydration of {beta}-C{sub 2}S and influenced the polymerization of calcium silicate hydrate. KOH and NaHCO{sub 3} caused excessive and early liberation heat of the {beta}-C{sub 2}S. The effect of NaHCO{sub 3} was more significant than that of KOH on the acceleration of hydration. The curing temperature was also an important factor in the acceleration of the hydration of {beta}-C{sub 2}S; the hydration was occurred much more actively at 40 degree C than at 20 degree C. The controlled {beta}-C{sub 2}S showed a much greater degree of polymerization of calcium silicate hydrate than did the alkali-added {beta}-C{sub 2}S. The hydrates of {beta}-C{sub 2}S were influenced by alkalies and temperature. The controlled {beta}-C{sub 2}S showed needle-like and wide needle-like shapes of calcium silicate hydrates, while the alkali-added {beta}-C{sub 2}S presented long and wide needle-like shapes and crumbled foil-like shapes of calcium silicate hydrates. The calcium silicate hydrates. The calcium silicate hydrates formed at high temperature exhibited also crumbled foil-like shapes. (author)

Park, C. [Ssangyong Research Center, Taejon (Korea)

2000-02-01

231

Minerals from Macedonia: XV. Sivec mineral assemble  

International Nuclear Information System (INIS)

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

2005-01-01

232

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

UK PubMed Central (United Kingdom)

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

Griffith LL; Shock EL

1997-04-01

233

A realistic molecular model of cement hydrates.  

UK PubMed Central (United Kingdom)

Despite decades of studies of calcium-silicate-hydrate (C-S-H), the structurally complex binder phase of concrete, the interplay between chemical composition and density remains essentially unexplored. Together these characteristics of C-S-H define and modulate the physical and mechanical properties of this "liquid stone" gel phase. With the recent determination of the calcium/silicon (C/S = 1.7) ratio and the density of the C-S-H particle (2.6 g/cm(3)) by neutron scattering measurements, there is new urgency to the challenge of explaining these essential properties. Here we propose a molecular model of C-S-H based on a bottom-up atomistic simulation approach that considers only the chemical specificity of the system as the overriding constraint. By allowing for short silica chains distributed as monomers, dimers, and pentamers, this C-S-H archetype of a molecular description of interacting CaO, SiO2, and H2O units provides not only realistic values of the C/S ratio and the density computed by grand canonical Monte Carlo simulation of water adsorption at 300 K. The model, with a chemical composition of (CaO)(1.65)(SiO2)(H2O)(1.75), also predicts other essential structural features and fundamental physical properties amenable to experimental validation, which suggest that the C-S-H gel structure includes both glass-like short-range order and crystalline features of the mineral tobermorite. Additionally, we probe the mechanical stiffness, strength, and hydrolytic shear response of our molecular model, as compared to experimentally measured properties of C-S-H. The latter results illustrate the prospect of treating cement on equal footing with metals and ceramics in the current application of mechanism-based models and multiscale simulations to study inelastic deformation and cracking.

Pellenq RJ; Kushima A; Shahsavari R; Van Vliet KJ; Buehler MJ; Yip S; Ulm FJ

2009-09-01

234

Hydration management at the end of life.  

UK PubMed Central (United Kingdom)

The management of parenteral hydration at the end of life remains controversial. The debate centers on whether and/or how often patients should be hydrated, the volume of hydration received, and the benefit verses side effects of parenteral hydration. In order to clarify the routine practice of physicians involved in the end-of-life care in Edmonton, Alberta, Canada, we investigated the routine management of hydration by attending physicians caring for patients dying in a palliative care unit (PCU) at Norwood Capital Care, and in acute care wards at the Royal Alexandra Hospital (RAH) both while receiving and while not receiving consult advice from the Palliative Care Program. We conducted a retrospective chart review of 50 consecutive patients who died in each of the 3 sites included in the study. Data from the last 7 days prior to and including the date of death (day 0) was recorded. The majority of patients at all sites received hydration. The volume of hydration ordered in the Norwood PCU site was significantly different compared to both RAH groups on all days studied (p < 0.005). The RAH palliative care group showed a trend for lower hydration volumes compared to the RAH acute care group with significant differences on days 1 and 2 (p < 0.05). Throughout the week, for all of the hydrated patients in the Norwood PCU site, hypodermoclysis (HDC) was ordered; for nearly all of the hydrated patients in the RAH acute care group, intravenous (IV) hydration was ordered; and for approximately one third of the hydrated RAH palliative care consult group HDC was ordered, and for the remainder IV hydration was ordered. The RAH acute care group represented the largest percentage of hydrated patients receiving diuretics while the Norwood hospice site represented the lowest. The data raise the possibility that more patients in the RAH acute care group were overhydrated and may have developed symptoms such as edema, ascites, and respiratory distress. This study suggests that hydration at the end of life is managed differently in different settings of care and highlights areas for education to improve management.

Lanuke K; Fainsinger RL; DeMoissac D

2004-04-01

235

Gas hydrates in ocean bottom sediments  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates belong to a special category of chemical substances known as inclusion compounds. An inclusion compound is a physical combination of molecules in which one component becomes trapped inside the other. In gas hydrates, gas molecules are physically trapped inside an expanded lattice of water molecules. The pressures and temperatures beneath Artic water depths greater than 1,100 ft (335 m) and subtropical water depths greater than 2,000 ft (610 m) are suitable for the formation of methane hydrate. Theoretical depths to the base of a gas hydrate layer in ocean bottom sediments are determined by assuming: (1) a constant hydrostatic pressure gradient, (2) two typical hydrothermal gradients, (3) variable geothermal gradients, and (4) pure methane hydrated with connate seawater. In addition to pressure and geothermal gradient, other variables affecting the stability of gas hydrate are examined. These variables are hydrothermal gradient, sediment thermal conductivity, heat flow, hydrate velocity, gas composition, and connate water salinity. If these variables are constant in a lateral direction and the above assmptions are valid, a local geothermal gradient can be determined if the depth to the base of a gas hydrate is known. The base of the gas hydrate layer is seen on seismic profiles as an anomalous reflection nearly parallel to the ocean bottom, cross-cutting geologic bedding plane reflections, and generally increasing in sub-ocean bottom time with increasing water depth. The acoustic impedance is a result of the relatively fast velocity hydrate layer overlying slower velocity sediments. In addition, free gas may be trapped beneath the hydrate, thereby enhancing the reflection.

MacLeod, M.K.

1982-12-01

236

Hydration of arsenic oxyacid species.  

Science.gov (United States)

The bond distances in hydrated arsenic oxyacid species in aqueous solution have been studied by EXAFS spectroscopy and large angle X-ray scattering, LAXS. These results have been compared to structures in the solid state, as found in an extensive survey of available crystal structures. Protonated oxygen atoms can be distinguished with a longer As-O distance for both arsenic(V) and arsenic(III) species in the crystalline state. However, the average As-O distance for the H(n)AsO(4)((3-n)-) species (0 ?n? 3) remains the same. These average values are slightly shorter, ca. 0.02 Å, than in aqueous solution due to the hydration as determined by EXAFS and LAXS. The K absorption edges for arsenic(V) and arsenic(III) species are separated by 4.0 eV, and the shape of the absorption edges differs as well. Small but significant differences in the absorption edge features are seen between the neutral acids and the charged oxyacid species. The most important arsenic species from an environmental point of view is arsenous acid, As(OH)(3). In addition to arsenous acid, we have used orthotelluric acid, Te(OH)(6), for comparison with arsenous acid and for detailed studies of the hydration of covalently bound hydroxo groups. Arsenous acid cannot be studied with the same accuracy as orthotelluric acid, due to a relatively low solubility of As(2)O(3)(s) in neutral to acidic aqueous solution. The results from the DDIR studies support the assignment of As(OH)(3) as a weak structure maker analogous to Te(OH)(6), both being neutral weak oxyacids. PMID:23135316

Mähler, Johan; Persson, Ingmar; Herbert, Roger B

2012-11-07

237

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; Guerra Isabela; Barros Turíbio Leite de

2003-01-01

238

Hydration of arsenic oxyacid species.  

UK PubMed Central (United Kingdom)

The bond distances in hydrated arsenic oxyacid species in aqueous solution have been studied by EXAFS spectroscopy and large angle X-ray scattering, LAXS. These results have been compared to structures in the solid state, as found in an extensive survey of available crystal structures. Protonated oxygen atoms can be distinguished with a longer As-O distance for both arsenic(V) and arsenic(III) species in the crystalline state. However, the average As-O distance for the H(n)AsO(4)((3-n)-) species (0 ?n? 3) remains the same. These average values are slightly shorter, ca. 0.02 Å, than in aqueous solution due to the hydration as determined by EXAFS and LAXS. The K absorption edges for arsenic(V) and arsenic(III) species are separated by 4.0 eV, and the shape of the absorption edges differs as well. Small but significant differences in the absorption edge features are seen between the neutral acids and the charged oxyacid species. The most important arsenic species from an environmental point of view is arsenous acid, As(OH)(3). In addition to arsenous acid, we have used orthotelluric acid, Te(OH)(6), for comparison with arsenous acid and for detailed studies of the hydration of covalently bound hydroxo groups. Arsenous acid cannot be studied with the same accuracy as orthotelluric acid, due to a relatively low solubility of As(2)O(3)(s) in neutral to acidic aqueous solution. The results from the DDIR studies support the assignment of As(OH)(3) as a weak structure maker analogous to Te(OH)(6), both being neutral weak oxyacids.

Mähler J; Persson I; Herbert RB

2013-02-01

239

Hydration behaviour of polyhydroxylated fullerenes  

International Nuclear Information System (INIS)

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

2011-10-28

240

Biopersistence of nonfibrous mineral particles in the respiratory tracts of subjects following occupational exposure.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transmission electron microscopy analysis (TEMA) was used to analyze the bronchoalveolar lavage fluid (BALF) of 262 subjects occupationally exposed (OE) to nonfibrous mineral particles (NFMP) and 42 controls not occupationally exposed to mineral dusts. OE subjects were divided into three groups acco...

Pairon, J C; Billon-Galland, M A; Iwatsubo, Y; Bernstein, M; Gaudichet, A; Bignon, J; Brochard, P

 
 
 
 
241

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

International Nuclear Information System (INIS)

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

2003-01-01

242

Direct determination of gas hydrate stability using recovered natural gas hydrate sample  

Energy Technology Data Exchange (ETDEWEB)

A method for a direct determination of the stability conditions of natural gas hydrate, suitable for recovered natural gas hydrate samples, has been developed. A small-volume pressure cell fitted with a pressure transducer and a temperature sensor was designed and built for making such measurements. The principle of the method is that the pressure in the cell will increase up to the equilibrium value for the gas hydrate at a certain temperature as gas is released from dissociating hydrate. As long as there is sufficient hydrate in the cell, such direct determinations of equilibrium conditions are possible by just warming the sample. A test on a synthetic methane hydrate sample was used to confirm the effectiveness of the method. Subsequently it was applied to natural hydrates recovered from the Cascadia Margin. (Author)

Lu, Hailong; Ripmeester, John; Das, Hamendra

2005-07-01

243

Glassy character of DNA hydration water.  

UK PubMed Central (United Kingdom)

The coherent excitations of DNA hydration water at 100 K have been investigated by neutron scattering spectroscopy to extract the excess signal of D(2)O-hydrated DNA with respect to dry DNA samples. A structural characterization of the sample, through the analysis of the static structure factor, has suggested that DNA hydration water is largely in an amorphous state up to high hydration degree, with only a small contribution coming from slightly deformed crystalline ice. To describe the inelastic spectra of DNA hydration water, we exploited a phenomenological model already applied in similar disordered systems, such as bulk water (Sacchetti et al. Phys. Rev. E2004, 69, 061203; Petrillo et al. Phys. Rev. E2000, 62, 3611-3618; Sette et al. Phys. Rev. Lett.1996, 77, 83-86) and protein hydration water (Orecchini et al. J. Am. Chem. Soc.2009, 131, 4664-4669). Over the low-energy range, the coherent dynamics of DNA hydration water is characterized by a branch at about 7.5 meV, a value slightly larger than that of bulk water. An additional mode in the energy range 20-35 meV is found, with a wavevector dependence seemingly connected with the structural features of amorphous ice. The ensemble of the results supports the glassy nature of DNA hydration water.

Paciaroni A; Orecchini A; Goracci G; Cornicchi E; Petrillo C; Sacchetti F

2013-02-01

244

Maintaining hydration in enteral tube feeding.  

UK PubMed Central (United Kingdom)

Although recognition of the importance of hydration is increasing, there is little research relating to hydration in enterally fed patients. An online survey found a lack of evidence-based guidance and a need for a greater understanding of this area.

Best C

2013-07-01

245

Furnace Injection of Pressure Hydrated Lime.  

Science.gov (United States)

Pressure-hydrators are used to produce a highly reactive sorbent with a surface area and pore size distribution which enables maximum utilization of available calcium. The hydrator vessel is operated at pressures of 90 to 150 psig with temperatures up to ...

G. F. Weber M. H. Bobman T. P. Dorchak

1985-01-01

246

Influence of polysaccharides on cement hydration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. Portland...

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

247

Hydration for a series of hydrocarbons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The hydrophobic hydration in a series of hydrocarbons is probed by using molecular dynamics simulations. The solutes considered range from methane to octane. Examination of the shapes of the hydration shell suggests that there is no single stable structure surrounding these solutes. The structure of...

Mountain, Raymond D.; Thirumalai, D.

248

Multicomponent modelling of Portland cement hydration reactions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 se...

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

249

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

250

A new geotechnical gas hydrates research laboratory  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates encapsulate natural gas molecules in a very compact form, as ice-like compounds composed of water molecules. Permafrost environments and offshore areas contain vast quantities of gas hydrates within soil and rock. This paper describes the role played by gas hydrates in submarine slope instability, their potential as a sustainable energy source, and their effects on global climate change. A new state-of-the-art laboratory located at the University of Calgary, which was developed to study the geomechanical behaviour of gas hydrate-sediment mixtures, was also presented. A specialized high pressure low temperature triaxial apparatus capable of performing a suite of tests on gas hydrate-sediment mixtures is housed in this laboratory. Extensive renovations were required in order to enable the use of methane gas to simulate natural hydrate formation conditions. The laboratory is specifically designed to examine the properties and behaviour of reconstituted gas hydrate-sediment mixtures and natural gas hydrate core samples. 26 refs., 9 figs.

Grozic, J.L.H. [Calgary Univ., AB (Canada)

2003-07-01

251

Evaluation of hydration indexes in kale leaves  

Scientific Electronic Library Online (English)

Full Text Available 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 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 ( (more) @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.

Calbo, Adonai G.; Ferreira, Marcos D.

2011-01-01

252

Free energy of hydration of niobium oxide  

Energy Technology Data Exchange (ETDEWEB)

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

Plodinec, M.J.

1996-08-21

253

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

254

Methane hydrates in the Chilean continental margin  

Scientific Electronic Library Online (English)

Full Text Available 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, seismic 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 t (more) he 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.

Morales G., Esteban

2003-08-01

255

Volume of hydration in terminal cancer patients.  

UK PubMed Central (United Kingdom)

In this retrospective study we reviewed the volume and modality of hydration of consecutive series of terminal cancer patients in two different settings. In a palliative care unit 203/290 admitted patients received subcutaneous hydration for 12 +/- 8 days at a daily volume of 1015 +/- 135 ml/day. At the cancer center, 30 consecutive similar patients received intravenous hydration for 11.5 +/- 5 days (P > 0.2) but at a daily volume of 2080 +/- 720 ml/day (P < 0.001). None of the palliative care unit patients required discontinuation of hydration because of complications. Hypodermoclysis was administered mainly as a continuous infusion, an overnight infusion, or in one to three 1-h boluses in 62 (31%), 98 (48%) and 43 (21%) patients, respectively. Our findings suggest that, in some settings, patients may be receiving excessive volumes of hydration by less comfortable routes such as the intravenous route. Increased education and research in this area are badly needed.

Bruera E; Belzile M; Watanabe S; Fainsinger RL

1996-03-01

256

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

257

The kinetics on hydrate formation in pipelines  

Energy Technology Data Exchange (ETDEWEB)

This study presents the experimental apparatus of flow loop type to investigate the hydrate plugging phenomena. The experiments for formation and dissociation of methane hydrate were conducted using the experimental apparatus setup in this study. Through the experiments, (gas + water + hydrate) three-phase equilibrium conditions were measured and enthalpy change in the dissociation process was analyzed based on the equilibrium results. The equilibrium conditions and the enthalpy of dissociation have been found to be consistent with previously published reference data. To examine the effect of hydrate formation under the flowing condition, experiments were carried out at varying flow velocities under a constant pressure. As a result, hydrate forming temperature tends to increase linearly with increasing flow velocity. Therefore, it was verified experimentally that flow velocity can be considered as one of the significant factors triggering the increase in the formation temperature. (Author)

Lee, Jeong; Baek, Young [Korea Gas Corp., Incheon (Korea); Sung, Won [Hanyang Univ., Seoul (Korea)

2005-07-15

258

Experimental Setup to Characterize Bentonite Hydration Processes  

International Nuclear Information System (INIS)

[en] 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

2001-01-01

259

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

1990-01-01

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

2004-07-01

 
 
 
 
261

Gas hydrate influence on deepwater slope stability  

Energy Technology Data Exchange (ETDEWEB)

Solid ice-gas compounds called gas hydrates occur in deep ocean sediments around the world. It is known that when they melt, the solid ice converts to gas and water. If this happens in slope sediments, landslides might result. A study of relationships between slope stability and gas hydrates shows that there are many ways in which changes in the geologic environment may cause gas hydrates to melt. One example is sea level lowering of the magnitude experienced during the Pleistocene; the pressure decrease reduces the stability of the hydrate. Another is warming of hydrates by increased geothermal heat flow associated with the growth of salt diapirs beneath the region. Geologic changes such as these were modeled using classical 1-D heat flow theory. Typical values for sediment and hydrate properties were used in a variety of potential geologic and environmental conditions that characterize some continental slope regions. Emphasis was given to interactions between the rate of geologic change and the rate of hydrate melt within the sediment. The latter is controlled by thermal properties of the sediment (resistivity and heat capacity) and hydrates (particularly the latent heat). An additional factor was the rate of change of excess pore water pressures in the sediment in reaction to the expansion of melting hydrate. The results show that the dynamic interactions between these phenomena are equally as important to slope stability as the size of the hypothesized geologic change or the regional slope gradient. Other crucial factors include the water depth, the origin of the hydrate from biologic or reservoir sources, and the strength of the sediment.

Dunlap, W.A. (Texas A and M Univ., College Station (USA)); Hooper, J.R. (Fugro-McClelland, Inc., Houston, TX (USA))

1990-06-01

262

Overview on Hydrate Coring, Handling and Analysis  

Energy Technology Data Exchange (ETDEWEB)

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

Jon Burger; Deepak Gupta; Patrick Jacobs; John Shillinglaw

2003-06-30

263

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

264

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

265

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

Science.gov (United States)

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

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

2011-12-01

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

Diffusion of CO2 During Hydrate Formation and Dissolution; A  

International Nuclear Information System (INIS)

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

2002-01-01

268

Gas Hydrate Storage of Natural Gas  

Energy Technology Data Exchange (ETDEWEB)

Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a lower heat transfer rate in the internal heat exchanger than was designed. It is believed that the fins on the heat-exchanger tubes did not make proper contact with the tubes transporting the chilled glycol, and pairs of fins were too close for interior areas of fins to serve as hydrate collection sites. A correction of the fabrication fault in the heat exchanger fin attachments could be easily made to provide faster formation rates. The storage success with the POC process provides valuable information for making the process an economically viable process for safe, aboveground natural-gas storage.

Rudy Rogers; John Etheridge

2006-03-31

269

Universal ripper miner  

Energy Technology Data Exchange (ETDEWEB)

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

270

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

Science.gov (United States)

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

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

2013-01-01

271

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

Science.gov (United States)

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

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

2012-09-01

272

The development path for hydrate natural gas  

Energy Technology Data Exchange (ETDEWEB)

This paper discussed issues related to the development of a gas hydrate industry. Technical and economic hurdles must be overcome in order to realize the energy potential in the world's gas hydrate deposits. Exploration and recovery scenarios are now being modelled in order to understand the factors that control the formation of the deposits. Methods to determine the porosity and permeability of hydrate reservoirs are also being developed. Resource assessments must first identify suitable hosts for hydrate production and recovery. Exploration efforts must continue to focus on determining the geological and depositional characteristics of natural hydrate systems. Significant economic considerations will also need to be addressed before the gas hydrate industry can be fully commercialized. Capital expenses and high drilling costs associated with deep water drilling may also impede development. Hydrate processing capabilities must also be developed in existing gas processing facilities in order to ensure their economic feasibility. It was concluded that commercialization of the resource will depend on the development of suitable targets. 7 refs., 1 fig.

Johnson, A.H. [Hydrate Energy International, Kenner, LA (United States)

2008-07-01

273

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

274

Influence of Surface Chemistry and Charge on Mineral-RNA Interactions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the results of large-scale molecular simulations, run over several tens of nanoseconds, of 25-mer sequences of single-stranded ribonucleic acid (RNA) in bulk water and at the surface of three hydrated positively charged MgAl layered double hydroxide (LDH) minerals. The three LDHs differ i...

Swadling, JB; Suter, JL; Greenwell, HC; Coveney, PV

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

2007-01-01

276

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

277

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 US 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 and D in the area of onshore hydrate deposition. They plan to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. They 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. They 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. They hope to correlate geology, geophysics, logs, and drilling and production data to allow reservoir models to be calibrated. Ultimately, the goal is to form an objective technical and economic evaluation of reservoir potential in Alaska.

Thomas E. Williams; Keith Millheim; Buddy King

2003-12-01

278

In situ speciation and distribution of toxic selenium in hydrated roots of cowpea.  

Science.gov (United States)

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

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

2013-07-08

279

In situ speciation and distribution of toxic selenium in hydrated roots of cowpea.  

UK PubMed Central (United Kingdom)

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

Wang P; Menzies NW; Lombi E; McKenna BA; de Jonge MD; Paterson DJ; Howard DL; Glover CJ; James S; Kappen P; Johannessen B; Kopittke PM

2013-09-01

280

Natural gas hydrates in flow assurance  

CERN Multimedia

With millions of kilometres of onshore and offshore oil and gas pipelines in service around the world, pipelines are the life's blood of the world. Notorious for disrupting natural gas production or transmission, the formation of natural gas hydrates can cost a company hundreds of millions and lead to catastrophic equipment breakdowns and safety and health hazards. Written by an international group of experts, Natural gas Hydrates in Flow Assurance provide an expert overview of the practice and theory in natural gas hydrates, with applications primarily in flow assurance. Compact and easy t

Koh, Carolyn Ann; Sloan, E Dendy

2010-01-01

 
 
 
 
281

Seismic imaging of gas hydrate reservoir heterogeneities  

Science.gov (United States)

Natural gas hydrate, a type of inclusion compound or clathrate, are composed of gas molecules trapped within a cage of water molecules. The presence of gas hydrate has been confirmed by core samples recovered from boreholes. Interests in the distribution of natural gas hydrate stem from its potential as a future energy source, geohazard to drilling activities and their possible impact on climate change. However the current geophysical investigations of gas hydrate reservoirs are still too limited to fully resolve the location and the total amount of gas hydrate due to its complex nature of distribution. The goal of this thesis is twofold, i.e., to model (1) the heterogeneous gas hydrate reservoirs and (2) seismic wave propagation in the presence of heterogeneities in order to address the fundamental questions: where are the location and occurrence of gas hydrate and how much is stored in the sediments. Seismic scattering studies predict that certain heterogeneity scales and velocity contrasts will generate strong scattering and wave mode conversion. Vertical Seismic Profile (VSP) techniques can be used to calibrate seismic characterization of gas hydrate expressions on surface seismograms. To further explore the potential of VSP in detecting the heterogeneities, a wave equation based approach for P- and S-wave separation is developed. Tests on synthetic data as well as applications to field data suggest alternative acquisition geometries for VSP to enable wave mode separation. A new reservoir modeling technique based on random medium theory is developed to construct heterogeneous multi-variable models that mimic heterogeneities of hydrate-bearing sediments at the level of detail provided by borehole logging data. Using this new technique, I modeled the density, and P- and S-wave velocities in combination with a modified Biot-Gassmann theory and provided a first order estimate of the in situ volume of gas hydrate near the Mallik 5L-38 borehole. Our results suggest a range of 528 to 768x10 6 m3/km2 of natural gas trapped within hydrate, nearly an order of magnitude lower than earlier estimates which excluded effects of small-scale heterogeneities. Further, the petrophysical models are combined with a 3-D Finite Difference method to study seismic attenuation. Thus a framework is built to further tune the models of gas hydrate reservoirs with constraints from well logs other disciplinary data.

Huang, Jun-Wei

282

Sedimentary and Related Minerals  

Science.gov (United States)

In this three-part exercise, students study hand samples and thin sections of sedimentary minerals and rocks. Part one - Box of Rocks: Students examine a tray of Halides, Carbonates, Borates, and Clays and record their physical properties, composition, habit, and occurence. They note chemical and physical similarities and differences of the minerals. Part two - Definitions: Define a list of terms relevent to the lab. Part three - Minerals in Thin Section: Observe sedimentary minerals in thin section and answer questions about them.

Perkins, Dexter

283

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; Orhan Kavak

2004-01-01

284

Conversion of CH4-hydrate to CO2-hydrate in liquid CO2  

Energy Technology Data Exchange (ETDEWEB)

The recovering rate of CH4 from CH4-hydrate soaked in liquid CO2 was measured at 274-277 K and 4-5 MPa. The fugacity of CH4 in liquid CO2 was kept below its initial hydrate forming fugacity, while that of CO2 was much higher than the initial forming fugacity Of CO2-hydrate. The CH4-recovering rate in liquid CO2 was much lower than that in gaseous N2 which dose not make hydrate under the conditions. The composition of the hydrate measured at the end of the experiment indicated that the formation of CO2-hydrate consumed all the H2O molecules which had been encasing the recovered CH4. The observed phenomena was described by a mathematical model based on nonequilibrium thermodynamics for use in feasibility studies. 11 refs., 6 figs., 1 tab.

Hirohama, S.; Shimoyama, Y.; Wakabayashi, A. [Chiyoda Corp., Tokyo (Japan); Tatsuta, S. [Hokuriku Electric Power Co. Inc., Toyama (Japan); Nishida, N.

1996-12-20

285

Natural gas hydrate deposits: a review of in situ properties. [Hydrate bearing sediments  

Energy Technology Data Exchange (ETDEWEB)

Hydrates of natural gas exist in nature in the Arctic regions and underneath the sea floor. Worldwide reservoir estimates range as high as 10/sup 7/ trillion ft/sup 3/. Very little information is available about the physical properties of these deposits, thus making difficult their detection by remote geophysical surveys. Reviewed are experimental sonic and resistivity measurements on hydrates, hydrate-bearing sediment, and permafrost. Conclusions indicate that hydrate layers are characterized by anomalously high sonic velocities and resistivities, both of which are functions of the amount of liquid water associated with the hydrates in the rock matrix. An analogy between hydrate-bearing sediments and permafrost is used to propose simple quantitative relationships between liquid water content and the electrical resistivities and sonic velocities of the deposits. Electrical and sonic well-logging data are used to substantiate the basic conclusions of this review. 18 references, 6 figures, 2 tables.

Pearson, C.F.; Halleck, P.M.; McGuire, P.L.; Hermes, R.; Mathews, M.

1983-10-13

286

Investigation of the hydration and bioactivity of radiopacified tricalcium silicate cement, Biodentine and MTA Angelus.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Novel root-end filling materials are composed of tricalcium silicate (TCS) and radiopacifier as opposed to the traditional mineral trioxide aggregate (MTA) which is made up of clinker derived from Portland cement and bismuth oxide. The aim of this research was to characterize and investigate the hydration of a tricalcium silicate-based proprietary brand cement (Biodentine™) and a laboratory manufactured cement made with a mixture of tricalcium silicate and zirconium oxide (TCS-20-Z) and compare their properties to MTA Angelus™. METHODS: The materials investigated included a cement containing 80% of TCS and 20% zirconium oxide (TCS-20-Z), Biodentine™ and MTA Angelus™. The specific surface area and the particle size distribution of the un-hydrated cements and zirconium oxide were investigated using a gas adsorption method and scanning electron microscopy. Un-hydrated cements and set materials were tested for mineralogy and microstructure, assessment of bioactivity and hydration. Scanning electron microscopy, X-ray energy dispersive analysis, X-ray fluorescence spectroscopy, X-ray diffraction, Rietveld refined X-ray diffraction and calorimetry were employed. The radiopacity of the materials was investigated using ISO 6876 methods. RESULTS: The un-hydrated cements were composed of tricalcium silicate and a radiopacifier phase; zirconium oxide for both Biodentine™ and TCS-20-Z whereas bismuth oxide for MTA Angelus™. In addition Biodentine™ contained calcium carbonate particles and MTA Angelus™ exhibited the presence of dicalcium silicate, tricalcium aluminate, calcium, aluminum and silicon oxides. TCS and MTA Angelus™ exhibited similar specific surface area while Biodentine™ had a greater specific surface area. The cements hydrated and produced some hydrates located either as reaction rim around the tricalcium silicate grain or in between the grains at the expense of volume containing the water initially present in the mixture. The rate of reaction of tricalcium calcium silicate was higher for Biodentine™ than for TCS-20-Z owing to its optimized particle size distribution, the presence of CaCO? and the use of CaCl?. Tricalcium calcium silicate in MTA hydrated even more slowly than TCS-20-Z as evident from the size of reaction rim representative of calcium silicate hydrate (C-S-H) around tricalcium silicate grains and the calorimetry measurements. On the other hand, calcium oxide contained in MTA Angelus™ hydrated very fast inducing an intense exothermic reaction. Calcium hydroxide was produced as a by-product of reaction in all hydrated cements but in greater quantities in MTA due to the hydration of calcium oxide. This lead to less dense microstructure than the one observed for both Biodentine™ and TCS-20-Z. All the materials were bioactive and allowed the deposition of hydroxyapatite on the cement surface in the presence of simulated body fluid and the radiopacity was greater than 3mm aluminum thickness. SIGNIFICANCE: All the cement pastes tested were composed mainly of tricalcium silicate and a radiopacifier. The laboratory manufactured cement contained no other additives. Biodentine™ included calcium carbonate which together with the additives in the mixing liquid resulted in a material with enhanced chemical properties relative to TCS-20-Z prototype cement. On the other hand MTA Angelus™ displayed the presence of calcium, aluminum and silicon oxides in the un-hydrated powder. These phases are normally associated with the raw materials indicating that the clinker of MTA Angelus™ is incompletely sintered leading to a potential important variability in its mineralogy depending on the sintering conditions. As a consequence, the amount of tricalcium silicate is less than in the two other cements leading to a slower reaction rate and more porous microstructure.

Camilleri J; Sorrentino F; Damidot D

2013-05-01

287

Minerals leasing for landowners  

Energy Technology Data Exchange (ETDEWEB)

This report delineates the provisions of the legal codes of the 13 Southeastern states relating to minerals leasing. The introduction explains land ownership and land leasing in terms of mineral rights, and describes the basic elements which a lease conveyance must contain to be valid. A checklist gives the terms which must be included in all mineral leases.

1983-01-01

288

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

International Nuclear Information System (INIS)

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

2008-01-01

289

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) 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

2005-01-01

290

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

International Nuclear Information System (INIS)

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

2007-01-01

291

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

International Nuclear Information System (INIS)

[en] 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

1994-01-01

292

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

293

A pump-probe XFEL particle injector for hydrated samples  

CERN Multimedia

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

Weierstall, U; Spence, J C H

2011-01-01

294

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST  

Energy Technology Data Exchange (ETDEWEB)

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

Donn McGuire; Thomas Williams; Bjorn Paulsson; Alexander Goertz

2005-02-01

295

Gas hydrate formation in reversed micelles  

Energy Technology Data Exchange (ETDEWEB)

We describe a technique to modify protein solubility and optimize enzyme activity in reversed micellar solutions. The technique is based on the ability of hydrates of natural gas to form in the microaqueous phase. Clathrate hydrates are crystalline inclusions of water and gas, and their formation in bulk water has traditionally been studied with relevance to natural gas recovery. We have found that hydrates can form in the environment of the microaqueous pools of reversed micelles, and that their extent of formation can be well controlled through the thermodynamic variables of temperature and pressure. Additionally, formation of hydrates affects the size and aggregation number of the micelles, and thus influences the solubility and conformation of encapsulated proteins. We demonstrate how the concept can be used in two applications: (1) protein extraction into reversed micelles and subsequent recovery, and (2) optimization of enzyme activity in reversed micelles.

Nguyen, H.; Rao, A.M.; Phillips, J.B.; John, V.T.; Reed, W.F. [Tulane Univ., New Orleans, LA (United States)

1991-12-31

296

Oceanic hydrates: more questions than answers  

Energy Technology Data Exchange (ETDEWEB)

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.

Laherrere, Jean

2000-07-01

297

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

298

Vibrational dynamics of hydration water in amylose  

Energy Technology Data Exchange (ETDEWEB)

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.; Deriu, A.; Albanese, G. [Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Parma (Italy); Angelini, N. [CNR, Istituto per i Processi Chimico-Fisici, Via La Farina, 237, 98123 Messina (Italy)

2002-07-01

299

Vibrational dynamics of hydration water in amylose  

CERN Multimedia

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

300

Stockpiling Hydrated Lime-Soil Mixtures.  

Science.gov (United States)

The concept and feasibility of stockpiling and reusing hydrated lime-soil mixtures to stabilize particular areas on stabilization projects after the mixing contractor has departed were examined. In chemical stabilization of subgrades, situations often ari...

C. Sun T. C. Hopkins T. L. Bakcham

2007-01-01

 
 
 
 
301

Measurement of hydration of the coal surface  

Energy Technology Data Exchange (ETDEWEB)

Changes in surface hydration have been measured by measuring the force necessary to detach a coal plate from the surface of a liquid, and by measuring the control angle. Two factors affecting hydration were studied: the presence of an electrolyte and the temperature of the liquid. Hydration decreases at higher electrolyte concentrations, particularly those exceeding 10at-at3 mole/l. It also decreases with time, equilibrium not being reached for 5-6 hours. Contact angle differs for different salts, and there is no direct relationship between concentration of a given salt and the angle. Hydration decreases with increased temperature, and the relationship is linear between 5 and 90 C. (In Czech)

Barcal, M.

1980-08-01

302

Hydration lubrication: exploring a new paradigm.  

UK PubMed Central (United Kingdom)

Lubrication by hydration shells that surround, and are firmly attached to, charges in water, and yet are highly fluid, provide a new mode for the extreme reduction of friction in aqueous media. We report new measurements, using a mica surface-force balance, on several different systems which exhibit hydration lubrication, extending earlier studies significantly to shed new light on the nature and limits of this mechanism. These include lubrication by hydrated ions trapped between charged surfaces, and boundary lubrication by surfactants, by polyzwitterionic brushes and by close-packed layers of phosphatidylcholine vesicles. Sliding friction coefficients as low as 10(-4) or even lower, and mean contact pressures of up to 17 MPa or higher are indicated. This suggests that the hydration lubrication mechanism may underlie low-friction sliding in biological systems, in which such pressures are rarely exceeded.

Gaisinskaya A; Ma L; Silbert G; Sorkin R; Tairy O; Goldberg R; Kampf N; Klein J

2012-01-01

303

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; NORA A COMELLI; NORBERTO H FIRPO; ESTHER N PONZI; MARTA I PONZI

2008-01-01

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 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

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 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

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.

Thomas E. Williams; Keith Millheim; Bill Liddell

2005-02-01

307

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

308

Spectroscopic methods in gas hydrate research.  

UK PubMed Central (United Kingdom)

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

Rauh F; Mizaikoff B

2012-01-01

309

Methane hydrates: limitless energy or environmental timebomb?  

Energy Technology Data Exchange (ETDEWEB)

Methane hydrates are ice-like substances, comprised of natural gas and water compressed by intense pressure and extremely cold temperatures, found underwater and under permafrost. Researchers estimate that these ice-like structures may contain sufficient natural gas to service the planet's needs for energy for the next thousand years. One of the problems in exploiting this immense resource may be the accumulating scientific evidence labelling methane hydrate as the largest contributor to global warming. This paper describes a first-of-its-kind research effort studying methane hydrates, spearheaded by the Geological Survey of Canada, which includes more than 100 leading government and industry scientists from Canada, the United States, Germany, India, and China. Field work on Project Mallik 2002 wrapped up in March 2002 . Three wells of more than a kilometre in depth were drilled at the Mallik gas hydrate field on the shores of the Beaufort Sea in the Canadian Arctic, studying techniques for methane hydrate extraction, including new drilling techniques and production methods. As part of the project, scientists are also exploring the seemingly disruptive role that gas hydrates may play in global climate change, and to gather evidence to prove or disprove the growing speculation that a rapid release of methane into the atmosphere may be the chief explanation for the last ice age, and that methane hydrates may have contributed to extreme changes in climatic conditions over a a comparatively short period of no more than a few decades. There is clearly need for more research by Canada and other countries to fully understand the energy potential of hydrates, and their impact on climate change.

Wright, V.

2003-03-31

310

Method for preparation of cadmium chloride hydrate  

International Nuclear Information System (INIS)

[en] A method for preparation of cadmium chloride hydrate including treatment of cadmium oxide with hydrochloric acid, filtration of the prepared solution, its evaporation and hydration of the product carried out simultaneously under 10-150 mm Hg at boiling temperature is proposed. The proposed method permits to increase the product quality, provide homo=. geneity of its phase composition (CdCl2x2.5H2O required content) and increase labour productivity

1981-01-01

311

GULF OF MEXICO SEAFLOOR STABILITY AND GAS HYDRATE MONITORING STATION PROJECT  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-11-01

312

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.

1981-01-01

313

Stability of Mg-sulfate minerals in the presence of smectites: Possible mineralogical controls on H2O cycling and biomarker preservation on Mars  

Science.gov (United States)

Martian layered deposits and regolith at Gale Crater may contain multiple hydrated mineral phases, tentatively identified as hydrated Mg-sulfate minerals and smectites. We have used humidity buffer experiments to assess the stability of hydrated Mg-sulfate minerals in the presence of smectites in order to improve our understanding of the probable behavior of Mg-sulfate minerals within multiphase geological materials on Mars. A series of long-term experiments employed temperature (-25 to +23 °C) and relative humidity (RH) conditions (7-100%) that emulate near-equatorial martian surface conditions. Our results indicate that the hydration state of Mg-sulfate minerals is affected by the presence of RH-sensitive clay minerals (i.e., smectites). The formation of gypsum and bassanite in dry mineral mixtures via cation exchange between Ca-bearing smectite and Mg-sulfate minerals indicates that Ca-sulfate minerals may be useful indicators of H2O and metal mobility at Mars-relevant temperatures (-25 to +23 °C). The presence of smectites also suppresses deliquescence of Mg-sulfate minerals at 100% RH and low, but non-freezing, temperatures. Co-existence of smectites and Mg-sulfate minerals appears to buffer RH within mixtures of these minerals, which can result in production or preservation of Mg-sulfate phases that are inconsistent with measured values of atmospheric RH. Consequently, hydrated Mg-sulfate minerals may persist beyond their expected T-RH equilibrium fields on longer timescales within smectite-MgSO4 mixtures than in the pure MgSO4-H2O system. Dehydration of highly hydrated Mg-sulfate minerals appears to slow in the presence of smectite, which may have important implications for long-term preservation of organic biosignatures within Mg-sulfate crystals on Mars. Together, these observations suggest that Mg-sulfate mineral behavior (and thus cycling and bioavailability of H2O and metals) may be impacted by the presence of smectites within mineralogically complex martian layered deposits and regolith.

Wilson, Siobhan A.; Bish, David L.

2012-11-01

314

Dry FGD with high surface area hydrate  

Energy Technology Data Exchange (ETDEWEB)

Hydrated lime powder is often used in dry FGD processes taking place at low temperatures (Post-Combustion Dry Technology) as well as in processes run at high temperatures (In-Furnace Dry Technology). Extremely high absorption rates for acidic gas compounds with low sorbent consumption were obtained by using High Surface Area Hydrate (HSH) instead of commercial lime hydrate. For example: (1) An industrial flue gas at low temperature - containing 5,200 mg SO{sub 2}/Nm{sup 3} - is treated with HSH at a stoichiometric ratio < 3. The clean gas contains < 500 mg SO{sub 2}/Nm{sup 3}. These results are not achievable with commercial hydrated lime at a stoichiometric ratio > 5. (2) The flue gas of a coal fired power plant (appr. 200 MW{sub th}) containing 1,800 mg SO{sub 2}/Nm{sup 3} is treated at high temperature with HSH and conditioned downstream. With a stoichiometric ratio of appr. 1.3 the observed clean gas values are 400 mg SO{sub 2}/Nm{sup 3}; this is an absorption rate of appr. 75 %. Increasing the amount of HSH leads to higher absorption rates. Using commercial hydrated lime would double sorbent consumption and cause problems in the boiler. The results of comparisons between HSH and commercial hydrated limes from several industrial plants, coal fired power stations (capacity < 300 MW) and waste incinerators are described; typical plant data are presented.

Schwarzkopf, F. [Rheinische Kalksteinwerke GmbH, Savannah (Germany); Morum, B. [Rheinische Kalksteinwerke GmbH, Wuefrath (Germany)

1995-06-01

315

Photodissociation of hydrated hydrogen iodide clusters.  

Science.gov (United States)

Using high-level ab initio calculations and excited state ab initio molecular dynamics simulations, we show that hydrated iodic acids release hydrogen radicals and/or hydrogen molecules as well as iodine radicals upon excitation. Its photoreaction process involving charge transfer to the solvent takes place in four steps: 1) hydration of the acid, 2) charge transfer to water upon excitation of hydrated acid, 3) detachment of the neutral iodine atom, and 4) detachment of the hydrogen radical. The iodine detachment process from excited hydrated hydro-iodic acids is exothermic and the detachment of hydrogen radicals from hydrated hydronium radicals is spontaneous if the initial kinetic energy of the cluster is high enough to get over the activation barrier of the detachment. The complete release of the radicals can be understood in terms of kinetics. This study shows how the hydrogen and halogen radicals are dissociated and released from their hydrated acids. Simple experiments corroborate our predicted mechanism for the release of hydrogen molecules from iodic acid in water by ultraviolet light. PMID:18286552

Lee, Han Myoung; Kolaski, Maciej; Kim, Kwang S

2008-03-14

316

Photodissociation of hydrated hydrogen iodide clusters.  

UK PubMed Central (United Kingdom)

Using high-level ab initio calculations and excited state ab initio molecular dynamics simulations, we show that hydrated iodic acids release hydrogen radicals and/or hydrogen molecules as well as iodine radicals upon excitation. Its photoreaction process involving charge transfer to the solvent takes place in four steps: 1) hydration of the acid, 2) charge transfer to water upon excitation of hydrated acid, 3) detachment of the neutral iodine atom, and 4) detachment of the hydrogen radical. The iodine detachment process from excited hydrated hydro-iodic acids is exothermic and the detachment of hydrogen radicals from hydrated hydronium radicals is spontaneous if the initial kinetic energy of the cluster is high enough to get over the activation barrier of the detachment. The complete release of the radicals can be understood in terms of kinetics. This study shows how the hydrogen and halogen radicals are dissociated and released from their hydrated acids. Simple experiments corroborate our predicted mechanism for the release of hydrogen molecules from iodic acid in water by ultraviolet light.

Lee HM; Kolaski M; Kim KS

2008-03-01

317

Ground movements associated with gas hydrate production  

Energy Technology Data Exchange (ETDEWEB)

The mechanics of ground movements during hydrate production can be more closely simulated by considering similarities with ground movements associated with subsidence in permafrost regions than with gob compaction in a longwall mine. The purpose of this research work is to investigate the potential strata movements associated with hydrate production by considering similarities with ground movements in permafrost regions. The work primarily involves numerical modeling of subsidence caused by hydrate dissociation. The investigation is based on the theories of continuum mechanics , thermomechanical behavior of frozen geo-materials, and principles of rock mechanics and geomechanics. It is expected that some phases of the investigation will involve the use of finite element method, which is a powerful computer-based method which has been widely used in many areas of science and engineering. Parametric studies will be performed to predict expected strata movements and surface subsidence for different reservoir conditions and properties of geological materials. The results from this investigation will be useful in predicting the magnitude of the subsidence problem associated with gas hydrate production. The analogy of subsidence in permafrost regions may provide lower bounds for subsidence expected in hydrate reservoirs. Furthermore, it is anticipated that the results will provide insight into planning of hydrate recovery operations.

Siriwardane, H.J.

1992-10-01

318

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

2008-01-01

319

Canmore miners: coal miner portraits and stories  

Energy Technology Data Exchange (ETDEWEB)

Canmore was a coal mining town from 1886 until 1979, when Canmore Mines closed. Canmore history, underground mining, working conditions in the mines, the miner's life, and the Canmore Centennial Museum are briefly discussed. Most of the book consists of photographs of retired miners and their personal accounts of their experiences in the mines and of living in Canmore. The photographs span the period 1979-2002. 55 photos.

Chrismas, L.; McArthur, K. (eds.)

2002-07-01

320

Investigation of the water sorption properties of Mars-relevant micro- and mesoporous minerals  

Science.gov (United States)

Encouraged by recent results of the Mars Odyssey spacecraft mission and the OMEGA team (Mars Express) concerning water in equatorial latitudes between ±45° on Mars and the possible existence of hydrated minerals, we have investigated the water sorption properties of natural zeolites and clay minerals close to martian atmospheric surface conditions as well as the properties of Mg-sulfates and gypsum. To quantify the stability of hydrous minerals on the martian surface and their interaction with the martian atmosphere, the water adsorption and desorption properties of nontronite, montmorillonite, chabazite and clinoptilolite have been investigated using adsorption isotherms at low equilibrium water vapor pressures and temperatures, modeling of the adsorption equilibrium data, thermogravimetry (TG), differential scanning calorimetry (DSC), and proton magic angle spinning nuclear magnetic resonance measurements (1H MAS NMR). Mg-sulfate hydrates were also analyzed using TG/DSC methods to compare with clay mineral and zeolites. Our data show that these microporous minerals can remain hydrated under present martian atmospheric conditions and hold up to 2.5 25 wt% of water in their void volumes at a partial water vapor pressure of 0.001 mbar in a temperature range of 333 193 K. Results of the 1H MAS NMR measurements suggest that parts of the adsorbed water are liquid-like water and that the mobility of the adsorbed water might be of importance for adsorption-water-triggered chemistry and hypothetical exobiological activity on Mars.

Jänchen, Jochen; Bish, David L.; Möhlmann, Diedrich T. F.; Stach, Helmut

2006-02-01

 
 
 
 
321

Rocks, minerals, and a dusty world  

Energy Technology Data Exchange (ETDEWEB)

The Earth`s troposphere and hydrosphere contain abundant naturally generated dust. The ultimate source materials from which the terrestrially produced dust is generated are the various rock types exposed at the Earth`s surface. Natural dust is a composite of (1) lithic, primary mineral grains; (2) mineral grains formed by secondary chemical reactions; (3) volcanic ash and dust; (4) salts from sea sprays; (5) extra-terrestrial dust; and (6) biologic materials. In this paper the various pathways to the natural generation of dust (via the hydrologic cycle) will be discussed, and two geologically well-known natural dust sources will be described, paying particular attention to quantitative measurements of the dusts from these areas. General dust studies that provide data on possibly global background levels will be presented as well.. A few general aspects of the mineralogical characterization of dust particles and a discussion of some of the mineralogy of several mineral groups are first presented. 89 refs., 39 figs.

Klein, C. [Univ. of New Mexico, Albuquerque, NM (United States)

1993-12-31

322

Hydration during intense exercise training.  

UK PubMed Central (United Kingdom)

Hydration status has profound effects on both physical and mental performance, and sports performance is thus critically affected. Both overhydration and underhydration - if sufficiently severe - will impair performance and pose a risk to health. Athletes may begin exercise in a hypohydrated state as a result of incomplete recovery from water loss induced in order to achieve a specific body mass target or due to incomplete recovery from a previous competition or training session. Dehydration will also develop in endurance exercise where fluid intake does not match water loss. The focus has generally been on training rather than on competition, but sweat loss and fluid replacement in training may have important implications. Hypohydration may impair training quality and may also increase stress levels. It is unclear whether this will have negative effects (reduced training quality, impaired immunity) or whether it will promote a greater adaptive response. Hypohydration and the consequent hyperthermia, however, can enhance the effectiveness of a heat acclimation program, resulting in improved endurance performance in warm and temperate environments. Drinking in training may be important in enhancing tolerance of the gut when athletes plan to drink in competition. The distribution of water between body water compartments may also be important in the initiation and promotion of cellular adaptations to the training stimulus.

Maughan RJ; Meyer NL

2013-01-01

323

Avoiding hydrates in the petroleum industry: Kinetics of formation  

Energy Technology Data Exchange (ETDEWEB)

Natural gas hydrates significantly impact the economics of development of offshore hydrocarbon resources in deep water. Methods for avoiding hydrates that depend on kinetics of hydrate formation may replace thermodynamic methods. Hydrate growth rates measured on a quiescent drop of water were found to agree qualitatively with rates measured in a vigorously stirred reactor when normalized with respect to the area of contact between the gas and the liquid, or liquid suspension of hydrates. The Gibbs free energy change for hydrate formation is shown to be a good estimate of driving force for hydrate growth. Hydrate growth rates per unit area correlate with the driving force.Driving force calculations suggest that hydrate structures other than the thermodynamically favored structures may form.

Christiansen, R.L.; Bansal, V.; Sloan, E.D. Jr. [Colorado School of Mines, Golden, CO (United States)

1994-12-31

324

Quick Assessment of Potential Hydrate Promoters for Rapid Formation  

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

325

Thermodynamic properties of methane hydrate in quartz powder.  

Science.gov (United States)

Using the experimental method of precision adiabatic calorimetry, the thermodynamic (equilibrium) properties of methane hydrate in quartz sand with a grain size of 90-100 microm have been studied in the temperature range of 260-290 K and at pressures up to 10 MPa. The equilibrium curves for the water-methane hydrate-gas and ice-methane hydrate-gas transitions, hydration number, latent heat of hydrate decomposition along the equilibrium three-phase curves, and the specific heat capacity of the hydrate have been obtained. It has been experimentally shown that the equilibrium three-phase curves of the methane hydrate in porous media are shifted to the lower temperature and high pressure with respect to the equilibrium curves of the bulk hydrate. In these experiments, we have found that the specific heat capacity of the hydrate, within the accuracy of our measurements, coincides with the heat capacity of ice. The latent heat of the hydrate dissociation for the ice-hydrate-gas transition is equal to 143 +/- 10 J/g, whereas, for the transition from hydrate to water and gas, the latent heat is 415 +/- 15 J/g. The hydration number has been evaluated in the different hydrate conditions and has been found to be equal to n = 6.16 +/- 0.06. In addition, the influence of the water saturation of the porous media and its distribution over the porous space on the measured parameters has been experimentally studied. PMID:17845024

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

2007-09-11

326

Thermodynamic properties of methane hydrate in quartz powder.  

UK PubMed Central (United Kingdom)

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

Voronov VP; Gorodetskii EE; Safonov SS

2007-10-01

327

Minerals planning guidance: stability in surface mineral workings and tips  

Energy Technology Data Exchange (ETDEWEB)

New minerals planning guidance contained in this consultation draft is intended to give advice to mineral planning authorities, local planning authorities, mineral operators and others concerned with the development of mineral working and tipping or in the development of former mineral working sites and tips. It is aimed at reducing the potential impact of surface mineral working and mineral tipping due to instability. The document will be issued as MPG5.

NONE

1998-07-01

328

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 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)

2005-01-01

329

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

330

Industrial perspective on natural gas hydrates; Perspectives industrielles des hydrates de gaz naturel  

Energy Technology Data Exchange (ETDEWEB)

Natural gas hydrates are usually considered as possible nuisances in the development of oil and gas fields, mainly in deep water drilling operations and if multiphase transport technologies are to be examined. However they have an energetic potential value if economic recovery schemes are found for the enormous amounts of methane trapped in the hydrates naturally occurring in the earth crust ('white coal'). On another side, hydrates can be used for the safe and economic storage of natural gas, mainly in cold countries. In remote offshore areas, the use of hydrates for natural gas transportation is also presently considered as an economic alternative to the processes based on liquefaction or on compression. This paper presents some possible medium-term industrial perspectives, either to reduce the nuisance of hydrates or to exploit their potential applications. (authors)

Lachet, V.; Behar, E. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

2000-12-01

331

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-10-01

332

Experimental stability of magnesium sulfate hydrates that may be present on Mars  

Science.gov (United States)

Since the Viking missions in 1976, magnesium sulfates have been predicted to exist on the surface of Mars. Recent orbital measurements suggest that Mg-sulfates are rather ubiquitous on the martian surface. Chemical analyses by landers support the inference that Mg-sulfate hydrates may be one source of the significant quantities of equatorial near-surface hydrogen observed by the neutron and ?-ray spectrometers on the Mars Odyssey spacecraft. The present study was undertaken to examine stability relations among the various Mg-sulfate hydrates. Using saturated salt solutions to control water-vapor pressure at temperatures of 3, 23, 50, 63, and 75 °C, Mg-sulfate phases were allowed to equilibrate from 2 to 3 months to see which hydration states were formed or were stable. Starting materials consisted of hexahydrite (6H 2O), starkeyite (4H 2O), kieserite (1H 2O), a second monohydrate-polymorph available as a chemical reagent, and an anhydrous MgSO 4 reagent. Products created in this study included these minerals, along with epsomite (7H 2O), sanderite (2H 2O), amorphous MgSO 4 (1-2H 2O), several previously undescribed phases, one of which was quite persistent (2.4H 2O), and trace amounts of pentahydrite (5H 2O). As expected, Mg-sulfate stability is strongly dependent on water vapor pressure and temperature. Lower temperatures favor the more hydrated Mg-sulfates. However, the MgSO 4 system was found to be surprisingly complicated and is strongly dominated by metastability, sluggish kinetics, and reaction pathways. Unexpected results were frequently encountered, in addition to the formation of previously undescribed phases. Several of the hydrates also show significant metastable extensions, such that phase boundaries can only be approximated. For example, kieserite, which has been reported on Mars from OMEGA data, in addition to having a distinct stability region, is resistant to transformation and persists throughout temperature-RH space until very high relative humidities are achieved. Results of this study show that MgSO 4 hydrates in addition to epsomite, hexahydrite, and kieserite can persist and should not be overlooked when assessing possible Mg-sulfate minerals that can occur on Mars.

Chipera, Steve J.; Vaniman, David T.

2007-01-01

333

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

334

Foam stabilizing and hydration mechanism of cellular cement  

Energy Technology Data Exchange (ETDEWEB)

The effects of type, quantity and ratio of foam agent, foam stabilizing agent and accelerator on foam stabilization and hydration of cellular concrete are discussed. X-ray diffraction, heat weight loss curve, and scanning electron microscope methods are used to study the hydration process, the structure of hydration products, the mechanism of foam stabilization and hydration. The results are: the foam stabilization performance is affected by the valency and the type of metal ion in the mortar; the hydration process includes the initial, middle and later stages; the product of initial hydration period is AFt phase, AFm and aluminium gel are found a day later. 4 refs., 5 figs., 6 tabs.

Zhang, L.; Ning, Y.; Bi, J. [China Coal Material Corporation (China)

1996-04-01

335

Mineral statistics yearbook, 1990  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 3 figs., 38 tabs.

1991-01-01

336

Mineral statistics yearbook, 1992  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 3 figs., 50 tabs.

1993-01-01

337

Mineral statistics yearbook, 1991  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 3 figs., 50 tabs.

1992-01-01

338

Mineral statistics yearbook, 1988  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 3 figs., 36 tabs.

1990-01-01

339

Mineral statistics yearbook, 1987  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 3 figs., 38 tabs.

1988-01-01

340

Mineral statistics yearbook, 1986  

Energy Technology Data Exchange (ETDEWEB)

This report presents numerical data on fuel and industrial minerals industries in Saskatchewan. Fuel mineral production, sales, and disposition statistics are given for crude oil, natural gas, liquefied petroleum gas, and coal. Other minerals covered by this report are potash, sodium sulfate, salt, and uranium. A section on drilling statistics gives annual, monthly, and historical summaries of such data as well completions and abandonments, and number of meters drilled. Exploratory and development wells are both included. Summaries are also made of crown land dispositions: minerals rights committed, and petroleum/natural gas rights sales. 38 tabs.

1988-01-01

 
 
 
 
341

Minerals industry survey, 1984  

Energy Technology Data Exchange (ETDEWEB)

This is the seventh edition of the statistical survey commissioned by the Australian Mining Industry Council. It represents the most comprehensive review of the financial position of the Australian minerals industry and provides timely financial data on the minerals industry. The tables of this survey have been prepared for AMIC by Coopers and Lybrand, Chartered Accountants, based on information supplied to them in confidence by the respondent companies. For the purpose of the survey, the minerals industry has been defined as including exploration for, and extraction and primary processing of, minerals in Australia. The oil and gas industry is not included.

1984-01-01

342

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

343

Opacity reduction using dry hydrated lime injection  

Energy Technology Data Exchange (ETDEWEB)

This investigation studied the effects of injecting dry hydrated lime into flue gas to reduce sulfur trioxide (SO[sub 3]) concentrations and consequently stack opacity at the University of Missouri-Columbia power plant. The opacity was due to sulfuric acid mist forming at the stack from high SO[sub 3] concentrations. As a result of light scattering by the mist, a visible plume leaves the stack. Therefore, reducing high concentrations of SO[sub 2] reduces the sulfuric acid mist and consequently the opacity. To reduce SO[sub 3] concentrations, dry hydrated lime is periodically injected into the flue gas upstream of a baghouse and downstream of an induced draft fan. The hydrated lime is transported downstream by the flue gas and deposited on the filter bags in the baghouse forming a filter cake. The reaction between the SO[sub 3] and the hydrated lime takes place on the filter bags. The hydrated lime injection system has resulted in at least 95% reduction in the SO[sub 3] concentration and has reduced the opacity to acceptable limits. Low capital equipment requirements, low operating cost, and increasing bag life make the system very attractive to industries with similar problems. 10 refs., 2 figs., 5 tabs.

Wolf, D.E.; Seaba, J.P. (University of Missouri-Columbia, Columbia, MO (United States). Mechanical and Aerospace Engineering Dept.)

1994-07-01

344

Hydration of partially sulfated lime with water  

Energy Technology Data Exchange (ETDEWEB)

The reaction between water and partially sulfated lime particles was studied under isothermal conditions using a Calvet microcalorimeter. The rate and extent of hydration were followed as a function of time by monitoring the evolution of heat from the reaction chamber. Experiments were performed with spent sorbent particles from two industrial circulating fluidized bed combustors and with lime particles sulfated in the laboratory using a thermogravimetric analyzer. The effect of temperature (40--85 C), particle size (150--850 {micro}m) and extent of sulfation (CaSO{sub 4} conversions between 0--45%) on the rate of hydration was determined. The rate of hydration of the partially sulfated lime particles was found to be independent of particle size, to increase with increasing temperature and to decrease with increasing level of sulfation of the particles. The results of this study suggest that the rate of hydration of partially sulfated lime particles is controlled by the transport of water across the CaSO{sub 4} layer that surrounds the individual grains of CaO. The apparent activation energy for this process is of the order of 45 kJ/mol. A first order kinetic model is shown to correlate well the effect of time and temperature on the extent of hydration of spent sorbent particles from fluidized bed combustors.

Couturier, M.F.; Volmerange, Y.; Steward, F.

1999-07-01

345

Fragmentation and hydration of tektites and microtektites  

Science.gov (United States)

An examination of data collected over the last 30 years indicates that the percent of glass fragments vs. whole splash forms in the Cenozoic microtektite strewn fields increases towards the source crater (or source region). We propose that this is due to thermal stress produced when tektites and larger microtektites fall into water near the source crater while still relatively hot (>1150 ??C). We also find evidence (low major oxide totals, frothing when melted) for hydration of most of the North American tektite fragments and microtektites found in marine sediments. High-temperature mass spectrometry indicates that these tektite fragments and microtektites contain up to 3.8 wt% H2O. The H2O-release behavior during the high-temperature mass-spectrometric analysis, plus high Cl abundances (???0.05 wt%), indicate that the North. American tektite fragments and microtektites were hydrated in the marine environment (i.e., the H2O was not trapped solely on quenching from a melt). The younger Ivory Coast and Australasian microtektites do not exhibit much evidence of hydration (at least not in excess of 0.5 wt% H2O); this suggests that the degree of hydration increases with age. In addition, we find that some glass spherules (with 65 wt% SiO2 can undergo simple hydration in the marine environment, while impact glasses (with <65 wt% SiO2) can also undergo palagonitization.

Glass, B. P.; Muenow, D. W.; Bohor, B. F.; Meeker, G. P.

1997-01-01

346

Natural gas hydrates; Future fuel and energy source. Naturgasshydrater; Fremtidens drivstoff og energikilde  

Energy Technology Data Exchange (ETDEWEB)

The present article deals with natural gas hydrates as a fuel and energy source in future. Following fields are discussed: Hydrates in the petroleum industry; gas hydrates in reservoirs; hydrates for natural gas storage and distribution; future perspectives. 2 figs.

Kostic, S.; Svartaas, T.M. (Rogalandsforskning, Stavanger (Norway))

1991-01-01

347

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

Science.gov (United States)

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

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

2008-12-01

348

Surfactant adsorption and interfacial tension investigations on cyclopentane hydrate.  

UK PubMed Central (United Kingdom)

Gas hydrates represent an unconventional methane resource and a production/safety risk to traditional oil and gas flowlines. In both systems, hydrate may share interfaces with both aqueous and hydrocarbon fluids. To accurately model macroscopic properties, such as relative permeability in unconventional systems or dispersion viscosity in traditional systems, knowledge of hydrate interfacial properties is required. This work presents hydrate cohesive force results measured on a micromechanical force apparatus, and complementary water-hydrocarbon interfacial tension data. By combining a revised cohesive force model with experimental data, two interfacial properties of cyclopentane hydrate were estimated: hydrate-water and hydrate-cyclopentane interfacial tension values at 0.32 ± 0.05 mN/m and 47 ± 5 mN/m, respectively. These fundamental physiochemical properties have not been estimated or measured for cyclopentane hydrate to date. The addition of surfactants in the cyclopentane phase significantly reduced the cyclopentane hydrate cohesive force; we hypothesize this behavior to be the result of surfactant adsorption on the hydrate-oil interface. Surface excess quantities were estimated for hydrate-oil and water-oil interfaces using four carboxylic and sulfonic acids. The results suggest the density of adsorbed surfactant may be 2× larger for the hydrate-oil interface than the water-oil interface. Additionally, hydrate-oil interfacial tension was observed to begin decreasing from the baseline value at significantly lower surfactant concentrations (1-3 orders of magnitude) than those for the water-oil interfacial tension.

Aman ZM; Olcott K; Pfeiffer K; Sloan ED; Sum AK; Koh CA

2013-02-01

349

Hydration state and abundance of zeolites on Mars and the water cycle  

Science.gov (United States)

Recent experimental studies have suggested that zeolites, if present on the Martian surface, could undergo a strong diurnal cycle of hydration and dehydration with possible impact on the atmosphere. This study evaluates this possibility using a global model of hydration/dehydration of two different zeolites (clinoptilolite and chabazite) assuming actual diurnal, seasonal, and geographical temperature variations. If zeolites extensively cover the surface and undergo complete diurnal hydration/dehydration cycles as predicted from the water vapor adsorption isotherms, the resulting water content would be too high in both the surface material and the atmosphere, implying that the abundance of zeolites is low or that zeolites must exist in a more desiccated state. If the zeolite abundance is low with the same hydration behavior, the lowest mean surface water content would occur at the equator, which also does not agree with observations. If substantial hydration/dehydration occurs seasonally rather than diurnally, the latitudinal and seasonal variation of the water content becomes too large and the zeolite abundance would have to vary with season to match the observation, which is also unrealistic. The most realistic scenario is a diurnally and seasonally constant low hydration state of zeolites controlled by the annual maximum surface temperature, in addition to a low abundance. Using these assumptions, the global distribution of the water content in the near-surface dry layer inferred from Mars Odyssey High-Energy Neutron Detector (HEND) data can be roughly explained. The best estimate of the zeolite abundance in the surface material to account for the observed water content is, on global average, ~30% for Ca-clinoptilolite, ~35% for Na-clinoptilolite, ~55% for K-clinoptilolite, and ~15% for chabazite if no other hydrated minerals are present. Putative regional confinement of zeolites to the dust-rich regions generally worsens the correlation between the modeled and observed water content compared with the scenario with globally uniform zeolite distribution, implying that zeolites may be present in dust-poor regions as well. In any case, our study shows that the diurnal atmospheric water cycle is unlikely to be affected by zeolites on the Martian surface.

Tokano, Tetsuya; Bish, David L.

2005-09-01

350

Sulfur dioxide sorption reactivity of hydrated lime: effect of hydration method  

Energy Technology Data Exchange (ETDEWEB)

The Furnace Sorbent Injection (FSI) process is a relatively low capital cost technology for control of SO/sub 2/ emissions produced during combustion of high sulfur coal. A major factor in the total cost of the FSI concept is the effective utilization of the sorbent. In pilot plant tests performed by previous investigators, calcium utilization efficiencies (at Ca/S feed ratio of 2:1) ranged from 15 to 20% for limestone, 25 to 30% for dolomitic limestone, 20 to 30% for hydrated lime, and 35 to 40% for pressure-hydrated dolomitic lime. The low calcium utilizations observed in these any many other studies have motivated researchers to develop methods of producing more reactive calcium-based sorbents with the goal of reducing SO/sub 2/ removal costs. The objective of this investigation was to produce hydrated lime with high surface area. Three hydration methods were studied: (1) lime was hydrated with water or alcohol-water solutions, (2) lime was reacted with water at pressures and temperatures up to and exceeding supercritical conditions and the hydrated lime produced was ejected to atmospheric conditions, (3) lime was hydrated with steam. Sulfur dioxide sorption capacities were obtained by thermogravimetry and surface areas were determined by the BET (N/sub 2/) technique.

Moran, D.L.; Rostam-Abadi, M.; Harvey, R.D.; Frost, R.R.; Sresty, G.C.

1987-01-01

351

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

UK PubMed Central (United Kingdom)

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

Schicks JM; Luzi-Helbing M

2013-11-01

352

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

Science.gov (United States)

Hydrate formation processes and kinetics are still not sufficiently understood on a molecular level based on experimental data. In particular, the cavity formation and occupancy during the initial formation and growth processes of mixed gas hydrates are rarely investigated. In this study, we present the results of our time-depending Raman spectroscopic measurements during the formation of hydrates from ice and gases or gas mixtures such as CH4, CH4-CO2, CH4-H2S, CH4-C3H8, CH4-iso-C4H10, and CH4-neo-C5H12 at constant pressure and temperature conditions and constant composition of the feed gas phase. All investigated systems in this study show the incorporation of CH4 into the 5(12) cavities as first step in the initial stages of hydrate formation. Furthermore, the results imply that the initial hydrate phases differ from the resulting hydrate phase having reached a steady state regarding the occupancy and ratio of the small and large cavities of the hydrate. PMID:23871981

Schicks, Judith M; Luzi-Helbing, Manja

2013-06-29

353

PSC 424: Rocks and Minerals  

Science.gov (United States)

This is a webpage designed to give students access to basic information about rocks and minerals. Rocks and Minerals Introduction Video Basic Definitions- Mineral: a solid inorganic substance of natural occurrence Rock: a mixture of minerals Ways to identify a mineral: Hardness Luster (metallic/nonmetallic) Streak Color Rock Song Three basic rock types: Igneous Metamorphic Sedimentary Rock Cycle Animation ...

Graham, Ms.

2011-10-13

354

Thirst and hydration status in everyday life.  

UK PubMed Central (United Kingdom)

Water is an essential nutrient for all persons; thus, maintaining a chronic state of optimal hydration is recognized to provide health benefits. Fluid balance is maintained via thirst, a feedback-controlled variable, regulated acutely by central and peripheral mechanisms. However, voluntary drinking is also a behavior influenced by numerous social and psychological cues. Therefore, whether "thirst-guided" drinking maintains optimal hydration status is a multifactorial issue. Thirst perception is typically assessed by subjective ratings using either categorical or visual analog scales; however, which instrument yields greater sensitivity to change in hydration status has not been examined. Ratings of thirst perception do not always yield predictable patterns of voluntary drinking following dehydration; therefore, perceived thirst and ad libitum drinking are not equivalent measures of human thirst. The recommendation "drink to thirst" is frequently given to healthy individuals during daily life. However, factors and conditions (e.g., age, disease) that influence thirst should be recognized and probed further.

Millard-Stafford M; Wendland DM; O'Dea NK; Norman TL

2012-11-01

355

Hydration for recreational sport and physical activity.  

UK PubMed Central (United Kingdom)

This review presents recommendations for fluid needs and hydration assessment for recreational activity. Fluid needs are based on sweat losses, dependent on intensity and duration of the activity, and will vary among individuals. Prolonged aerobic activity is adversely influenced by dehydration, and heat exposure will magnify this effect. Fluid needs predicted for running 5-42 km at recreational paces show that fluid losses are <2% body mass; thus, aggressive fluid replacement may not be necessary. Competitive paces result in greater fluid losses and greater fluid needs. Fluid needs for recreational activity may be low; however, carbohydrate consumption (sport drinks, gels, bars) can benefit high-intensity (? 1 h) and less-intense, long-duration activity (? 1 h). Spot measures of urine color or urine-specific gravity to assess hydration status have limitations. First morning urine concentration and body mass with gross thirst perception can be simple ways to assess hydration status.

Kenefick RW; Cheuvront SN

2012-11-01

356

Li+ hydration in concentrated aqueous solution  

International Nuclear Information System (INIS)

Neutron diffraction experiments were carried out on aqueous solutions of lithium chloride in heavy water at three concentrations - 14, 3.6 and 1 molal. The first-order isotopic difference method was applied to the lithium ions, and structural results were obtained for the Li+ hydration: the Li-O and Li-D near-neighbour distances in the first hydration shell remain the same at 1.95(3) and 2.5(5) A over the concentration range studied. However, there is an increase in coordination number from 3.2 at 14 molal to approx. 6.5 at 1 molal. There is also evidence for a relatively weak second hydration shell, which becomes displaced to larger distances at lower concentrations. (author)

1996-06-17

357

Fuel cell membrane hydration and fluid metering  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-01-01

358

Fuel cell membrane hydration and fluid metering  

Energy Technology Data Exchange (ETDEWEB)

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

359

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.

Naohiro Kobayashi; Takashi Minami; Atsushi Tani; Mikio Nakagoshi; Takeshi Sugahara; Kei Takeya; Kazunari Ohgaki

2012-01-01

360

Characterization of environmental exposure to mineral sands by PDMS technique  

International Nuclear Information System (INIS)

The risk to human health due to exposure to aerosols depends on the intake pattern, the mass concentration and the speciation of the elements present in airborne particles. In this work plasma desorption mass spectrometry (PDMS) was used to identify the speciation of metals present in the urine sample of an individual environmentally exposed to mineral sands airborne particles. Aerosol samples were collected at a Brazilian region with high concentration of mineral sands (Buena village), using a six-stage cascade impactor. The mass median aerodynamic diameter (MMAD) determined indicated that the airborne particulate was in the fine fraction of the aerosols. In order to characterize human exposure to mineral sands dust a sample from one inhabitant was analyzed by PDMS. The analysis of the results shows that the inhabitant incorporated metals from mineral sands and suggests that the source of aerosols is the mineral processing plant located at the village.

2003-01-01

 
 
 
 
361

Experimental studies on several significant problems related marine gas hydrate  

Energy Technology Data Exchange (ETDEWEB)

Simulation experiments were carried out to study marine gas hydrate in the aspects of the stability condition, methane amount in hydrate, and the relationship between hydrate saturation in sediment pores and the acoustic velocity using a series of designed apparatus along with special test techniques and means. The preliminary experimental results show that, (1) coarse sediment has little influence on stability conditions of hydrate in sediment, (2) methane content in hydrate depends upon temperature and pressure at the time of the hydrate formation, and (3) the acoustic velocity is intimately related with the hydrate saturation in the sediment pores. The obtained results have assured that valuable data and theoretic models can be acquired for exploring and evaluating marine gas hydrate resources. (Author)

Ye, Y.; Liu, C.; Liu, S.; Zhang, J.; Diao, S.

2005-07-01

362

Natural Gas Hydrate in Oceanic and Permafrost Environments  

Energy Technology Data Exchange (ETDEWEB)

This is the first book published on the emerging research field of naturally occurring gas hydrates (focusing on methane hydrate) that is not primarily a physical chemistry textbook. This book is designed as a broad introduction to the field of hydrate science, demonstrating the significance of the hydrate cycle to energy resource potential, seafloor stability, and global climate and climate change, along with other issues. The best known hydrate localities are described, as are research and laboratory methods and results. The book consists of chapters grouped in related themes that present up-to-date information on methane hydrate. Each of the contributing authors is expert in hydrate science and most have been carrying out research in hydrate for a considerable time.

Max, M.D. [ed.] [MDS Research, Washington D.C. (United States)

2000-07-01

363

Laboratory Investigation of Hydrated Lime as an Antistripping Additive.  

Science.gov (United States)

The purpose of this laboratory study was to determine the effectiveness of hydrated lime as an antistripping additive when used in bituminous mixes incorporating aggregates frequently used in such mixes in Virginia. The application of 1% hydrated lime to ...

G. W. Maupin

1983-01-01

364

Rapid Gas Hydrate Formation Processes: Will They Work?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation ...

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

365

Scientists Explore Large Gas Hydrate Field off Oregon Coast  

Science.gov (United States)

... jdauphin@nsf.gov Scientists Explore Large Gas Hydrate Field off Oregon Coast Details emerge of ... of frozen deposits of natural gas known as "gas hydrates." Funded largely by the National Science ...

366

Indochina area mineral prospects  

Energy Technology Data Exchange (ETDEWEB)

Prospects for commercial mining of various minerals are considered for Kampuchea (Cambodia), Laos, Vietnam, Myanmar (Burma) and Thailand. Mineral production is much below its geologic potential for economic and political reasons. Resource potential is limited to tin, tungsten, lead and zinc, barytes and gemstones, and coal. 1 fig.

1990-10-05

367

Minerals, Crystals and Gems  

Science.gov (United States)

This module introduces students to minerals, crystals, and gems by using pictures and discussions of some of the extraordinary specimens residing in the collections of the Smithsonian Institution. It includes three lessons in which they draw pictures of specimens, grow their own crystals of magnesium sulfate, and perform a scavenger hunt in which they look for minerals in commonly used objects and products.

368

Rocks and Minerals  

Science.gov (United States)

This description of rocks and minerals includes representatives of all three major groups: igneous, sedimentary, and metamorphic. Users can access introductory information about the three major rock types and the minerals that form them. A simple rock classification chart is included, with embedded links to a glossary and more detailed material for advanced learners.

369