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1

Clinker mineral hydration at reduced relative humidities  

DEFF Research Database (Denmark)

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

Jensen, Ole Mejlhede; Hansen, Per Freiesleben

1999-01-01

2

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.

3

Chemical characteristics of mineral trioxide aggregate and its hydration reaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Chang, Seok-woo

2012-01-01

4

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. ?? 2009 Elsevier Inc. All rights reserved.

Roach, L. H.; Mustard, J. F.; Swayze, G.; Milliken, R. E.; Bishop, J. L.; Murchie, S. L.; Lichtenberg, K.

2010-01-01

5

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 Fe"2"+, Ca"2"+ or p"5"+ ions

1985-01-01

6

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

7

Miners Exposed to Amphibole Mineral: A Retrospective Cohort Mortality Study.  

Science.gov (United States)

The mortality experience of a large cohort of Homestake Gold Mine (South Dakota) employees was investigated for possible connections between cummingtonite (1744080), grunerite (14567614), an amphibole mineral present in the mine, and cancer, specifically ...

S. D. Kaplan W. R. Gaffey

1981-01-01

8

Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2007-01-01

9

Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles  

Directory of Open Access Journals (Sweden)

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

A. Salam

2007-01-01

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 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

2007-07-01

11

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

Science.gov (United States)

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

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

2011-01-01

12

Hydrated Minerals and Fluvial Features In and Around the Melas Chasma Basin  

Science.gov (United States)

Using a synergy of mineralogy derived from CRISM data and morphology interpreted from HiRISE and CTX images, we map geologic units within and around the Melas basin. Numerous hydrated minerals and fluvial features indicate a complex aqueous history.

Weitz, C. M.; Williams, R. M. E.; Noe Dobrea, E.; Baldridge, A.

2012-03-01

13

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

14

Atomistic simulation of mineral surfaces: Their structure, hydration and growth  

International Nuclear Information System (INIS)

In this thesis, we have used atomistic simulation techniques to investigate the surface structure and stability of the biomineral barium sulfate and a number of important iron oxides, namely hematite, magnetite and goethite. We have studied the effect of the molecular adsorption of water on the surface structures and stabilities of all four minerals, and dissociative adsorption of water on the iron oxides. In addition, we have investigated the segregation of foreign ions to the surfaces of barium sulfate. Chapter 1 gives an overview of some previous studies of surfaces, employing both atomistic simulations and electronic structure calculations. Also discussed are some popular experimental analysis techniques used in surface characterisation. Chapter 2 describes the theoretical methods used in atomistic simulations and the mathematical methods used in the calculations, including the evaluation of surface energies. Chapter 3 introduces the potential model and discusses their reliability and transferability between structures. The potential parameters used in chapters 4-7 are given and where possible, compared with experiment. Chapter 4 describes the structures and stabilities of the pure surfaces of barium sulfate, and after the overgrowth of segregation of a layer of impurity ions at the surface. The modified crystal morphologies are discussed. Chapter 5 follows the work in the previous chapter by discussing the effect of the molecular adsorption of water at different coverages on the structure and stabilities of barium sulfate surfaces. The hydrated energies and surface energies are calculated. The second section of chapter 5 investigates structural influences on the growth of barium sulfate. In Chapter 6, the pure surfaces of hematite, magnetite and goethite are described. The surface relaxation are studied and equilibrium crystal morphologies compared with experimental findings. The surface structure of Fe2O3(00.1) under reducing conditions is also investigated. Chapter 7 discusses the dissociative and molecular adsorption of water to the iron oxide surfaces, after first verifying the potential against the structure of ?-FeOOH. The modified relaxations and morphologies are compared both with experiment and with those calculated in chapter 6. (author)

1999-01-01

15

Hydration adjacent to a deeply subducting slab: The roles of nominally anhydrous minerals and migrating fluids  

Science.gov (United States)

transport of water into the mantle has significant dynamical and geochemical implications. Dehydration of hydrous phases within the slab can introduce water into the transition zone and lower mantle, potentially hydrating nominally anhydrous minerals (NAM) and impacting the viscosity and density structure of the mantle over a wide area. We present models of fluid transport and mantle hydration in the vicinity of a deeply subducting slab, focusing on the fate of water released by deep dehydration reaction in the subducted serpentinized mantle. A sharp decrease in water storage capacity across the lower boundary of the transition zone may produce "secondary dehydration" of hydrated NAM, leading to precipitation of a hydrous fluid and heterogeneous hydration of the transition zone. Rapid fluid migration relative to the solid flow field can lead to a broad region of diffuse hydration within the upper mantle wedge and the potential for localized melt regions at the top of the transition zone coincident with fluid pathways. Slower fluid migration instead implies that the fluid phase can be transported deep into the lower mantle. Water stabilized in NAM and as a free fluid can initiate upwelling within and above the transition zone. A less abrupt change in water storage capacity across the base of the transition zone leads to high NAM water contents in a channel adjacent to the slab where viscosity is reduced. However, seismic and electromagnetic observations of hydration in the transition zone are most compatible with a sudden drop of water storage capacity.

Hebert, Laura B.; Montési, Laurent G. J.

2013-11-01

16

Hydrated Minerals at Yellowknife Bay, Gale Crater, Mars: Observations from Mastcam's Science Filters  

Science.gov (United States)

The Mastcam imaging investigation on the Mars Science Laboratory Curiosity rover can help constrain the mineralogy of sulfates and phyllosilicates present in the outcrop at Yellowknife Bay within Gale crater. The two Mastcams provide high-resolution morphological information, RGB color, and visible to near-infrared (Vis-NIR) multispectral data using narrowband 'science filters' covering 12 unique wavelengths between 432 and 1013 nm. The longest wavelength filters have some sensitivity to hydrated and/or hydroxylated minerals, as they can detect an absorption due to the 2?1 + ?3 H2O combination band and/or the 3? OH overtone when this band minimum occurs between 980 and 1000 nm (in water ice and some carbonates and hydrated sulfates). This narrow hydration band leads to a Mastcam spectral profile that is distinguishable from spectra of iron-bearing minerals with broad absorptions near 1000 nm. Here we use this spectral profile to help interpret the mineralogy hydrated surface materials in Mastcam multispectral images. The light-toned, Ca-sulfate fracture-fills of the Sheepbed Unit at Yellowknife Bay show some evidence for hydration in calibrated Mastcam spectra from sols 133-269. From comparisons to laboratory reflectance spectra of Ca-sulfate minerals convolved to Mastcam bandpasses, the hydration signature near 1013 nm is consistent with the presence of gypsum, but not bassanite or anhydrite. Several narrow fracture-fills observed in the Sheepbed Unit show no evidence for hydration, such as the thin veins at the John Klein and Cumberland drill sites. These observations are in accord with CheMin XRD observations (where bassanite and anhydrite were detected, but not gypsum). Mastcam hydration detections in nearby veins, however, suggest that Ca-sulfate hydration states may vary within the fracture-fill networks on local scales. The phyllosilicate-bearing outcrop of the Sheepbed Unit, when broken by Curiosity's wheels or brushed by the rover's Dust Removal Tool (Mastcam spectra from sols 172-174), has grayish hues and exhibits higher reflectances in the short-wavelength Mastcam filters (447 to 638 nm) than previously observed along the traverse. Some spectra show slightly negative near-IR spectral slopes, consistent with the presence of pyroxene and/or olivine in typical basaltic materials. These fresh surfaces do not exhibit the Mastcam hydration feature near 1013 nm, but the absence of the hydration signature in Mastcam spectra does not necessarily indicate an absence of hydrated minerals, and spectra of most phyllosilicates do not have an absorption detectable to Mastcam's 1013 nm filter. Many smectite spectra exhibit a 937 nm feature that should be detectable to Mastcam, however, and the absence of this feature places constraints on the phyllosilicate phases present at Yellowknife Bay.

Rice, M. S.; Bell, J. F.; Wellington, D. F.; Godber, A.; Hardgrove, C. J.; Ehlmann, B. L.; Grotzinger, J. P.; Kinch, K. M.; Clegg, S. M.; Fraeman, A. A.; Johnson, J. R.; Malin, M.; Stack, K.; Siebach, K. L.; Kah, L. C.; Team, M.

2013-12-01

17

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

Science.gov (United States)

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

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

2014-05-01

18

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

International Nuclear Information System (INIS)

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

1995-02-01

19

A study of chromosomal aberrations in miners exposed to diesel exhausts  

Energy Technology Data Exchange (ETDEWEB)

A study was made of chromosome aberrations in cultured lymphocytes from a group of 14 miners exposed to diesel exhausts and a reference group of office employees and construction workers. No increased frequency of chromosomal aberrations was observed. The frequency of chromosomal aberrations (both gaps and breaks) was, however, found to be associated with smoking.

Nordenson, I.; Sweins, A.; Dahlgren, E.; Beckman, L.

1981-03-01

20

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

2007-02-01

 
 
 
 
21

Alteration of Cytokine Profiles in Uranium Miners Exposed to Long-Term Low Dose Ionizing Radiation  

Science.gov (United States)

Objective. The aim of the study is to estimate the immune function through cytokine profiles in sera of uranium mines. Methods. Antibody arrays were used to detect 50 cytokines in sera of uranium miners. Miners who had continuously worked underground for <5 years were treated as control group and those who worked for ?5 years as experimental group. Results. Of 28 measurable cytokines, the release of IL-1?, IL-1RI, IL-15, IL-3, and IP-10 were significantly upregulated in the experimental group, and no cytokine was found significantly downregulated. Other proinflammatory cytokines such as IFN-?, IL-10, IL-6, and TNF? levels were slightly upregulated in the experimental group. With adjustment to age, BMI, and cigarette smoking, IL-1? and IL-3 levels increased significantly with underground time. Conclusion. Alteration of cytokine profiles in this study may indicate persistent inflammatory responses in uranium miners exposed to long-term low doses radiation.

Chen, YiShui; Li, XiaoLiang; Lei, ShuJie; Chen, QingFeng; Liu, JianXiang; Sun, QuanFu

2014-01-01

22

Cancer mortality among a group of fluorspar miners exposed to radon progeny  

International Nuclear Information System (INIS)

A cohort study of the mortality experience (1950-1984) of 1,772 Newfoundland underground fluorspar miners occupationally exposed to high levels of radon daughters (mean dose = 382.8 working levels months) has been conducted. Observed numbers of cancers of the lung, salivary gland, and buccal cavity and pharynx were significantly elevated among these miners. A highly significant relation was noted between radon daughter exposure and risk of dying of lung cancer; the small numbers of salivary gland (n = 2) and buccal cavity and pharynx (n = 6) cancers precluded meaningful analysis of dose response. Attributable and relative risk coefficients for lung cancer were estimated as 6.3 deaths per working level month per million person-years and 0.9% per working level month, respectively. Relative risk coefficients were highest for those first exposed before age 20 years. Cigarette smokers had relative and attributable risk coefficients comparable to those of nonsmokers. Relative risks fell sharply with age, whereas attributable risks were lowest in the youngest and oldest age groups. The results suggest that efforts to raise existing occupational exposure standards may be inappropriate

1988-01-01

23

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

24

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

International Nuclear Information System (INIS)

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

2009-02-01

25

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

2011-11-01

26

Laumontite mineralization in rocks exposed north of San Andreas Fault at Cajon Pass, southern California  

Science.gov (United States)

Laumontite of hydrothermal origin occurs in veins and as a replacement of the anorthite component of plagioclase in granitic and gneissic basement and overlying arkosic sandstone and conglomerate of the San Francisquito(?), Vaqueros and Cajon formations exposed in Cajon Pass north of the San Andreas fault. Accompanying alteration includes exsolution of albite from plagioclase, conversion of orthoclase to microcline and perthite, and oxidation of iron in biotite and magnetite to form a disseminated hematite stain. These changes are pervasive within 1 km of the fault but diminish to no alteration at 4 km. Granitic rocks close to the fault are crushed to highly fractured and contain a mosaic of laumontite veins. Veins occur along joints and minor faults in sedimentary rocks. Most veins are nearly vertical and trend northwest at a more northerly angle than the San Andreas. This mineralization is attributed to deep circulation of ground water in fractured and frictionally heated rocks along the San Andreas fault.

Vincent, Mark W.; Ehlig, Perry L.

27

Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters  

International Nuclear Information System (INIS)

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

1990-02-19

28

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

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

1988-01-01

29

Evaluation of a technique for separating organic material from mineral bone in individuals occupationally exposed to Pu  

Energy Technology Data Exchange (ETDEWEB)

The shaft portion of the left femur from an individual occupationally exposed to Pu was used to investigate the suitability of an ethylenediamine extraction technique to separate mineral bone from organic material. Marrow in the lumen was removed before the extraction technique was used and was analyzed separately for Pu. Ethylenediamine extraction did not remove Pu from the mineral bone, even after treatment for 48 h. The total amount and the concentration of Pu was highest in mineral bone and lowest in the extracted organic material.

Miglio, J.J.; Willis, L.C.

1987-06-01

30

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

Science.gov (United States)

Raman and infrared spectra of two polymorphous minerals with the chemical formula Fe3+(SO4)(OH)·2H2O, monoclinic butlerite and orthorhombic parabutlerite, are studied and the spectra assigned. Observed bands are attributed to the (SO4)2- stretching and bending vibrations, hydrogen bonded water molecules, stretching and bending vibrations of hydroxyl ions, water librational modes, Fe-O and Fe-OH stretching vibrations, Fe-OH bending vibrations and lattice vibrations. The O-H?O hydrogen bond lengths in the structures of both minerals are calculated from the wavenumbers of the stretching vibrations. One symmetrically distinct (SO4)2- unit in the structure of butlerite and two symmetrically distinct (SO4)2- units in the structure of parabutlerite are inferred from the Raman and infrared spectra. This conclusion agrees with the published crystal structures of both mineral phases. PMID:21658994

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

2011-09-01

31

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

International Nuclear Information System (INIS)

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

2005-01-01

32

Estimating the water content of hydrated minerals using reflectance spectroscopy. I. Effects of darkening agents and low-albedo materials  

Science.gov (United States)

The apparent strength of absorptions due to H 2O near 1.9 and 3 ?m in reflectance spectra is strongly affected by sample albedo. This study uses experimental and analytical approaches to quantify the effects of albedo on estimating the water content of hydrated minerals using various band parameters. We compare spectral band parameters for a series of low-albedo physical and numerical mixtures to measured water contents. Physical experiments consist of montmorillonite, clinoptilolite, and palagonite mixed with lesser amounts of carbon black and ilmenite, whereas numerical mixtures are composed of these host minerals mixed with a material of constant, low albedo. We find the effective single-particle absorption-thickness parameter provides the best correlation to water content, independent of composition and albedo, when derived from continuum-removed single scattering albedo spectra. Uncertainties in estimated water content are on the order of ±1 wt% using this method. The normalized optical path length parameter provides the best correlation to water content when using reflectance spectra, yielding estimates within ±1.6 wt% H 2O. The accuracy of these models is related to the physical nature of the darkening material. Scattering and absorption efficiencies are easier to model for intimate mixtures containing relatively large, dark grains than mixtures dominated by coatings of a fine-grained, strongly absorbing material. This suggests the physical properties that give rise to the albedo of a material are an important factor for accurate estimates of absolute water content.

Milliken, Ralph E.; Mustard, John F.

2007-08-01

33

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

34

[Rhabdomyolysis in a worker exposed to paraffinic mineral oils. Unusual association with bronchiolitis obliterans and organizing pneumonia (BOOP)].  

Science.gov (United States)

We describe a 29-year-old worker; exposed to metal dust, sawdust and paraffinic mineral oils in a factory producing accessories for leather articles and clothing, who came to observation with fever (39 degrees C), chest pain and marked increase of muscular enzymes. Chest computed tomography showed two areas of lung consolidation, that subsequently appeared enlarged with central escavation. Lung biopsy lead to the diagnosis of BOOP. The case has been reported to the judicial and workers' compensation authorities as probable occupational toxic myopathy. Indeed, exposure to paraffinic mineral oils is a known, though unusual, cause of rhabdomyolysis. The association with BOOP has never been previously described. PMID:18409764

Ragno, G; Brunetti, G; Scafa, F; Scelsi, M; Martellosio, V; Candura, S M

2007-01-01

35

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

International Nuclear Information System (INIS)

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

1994-01-01

36

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

Energy Technology Data Exchange (ETDEWEB)

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

Yokota, Satoshi; Mae, Tadahiko; Ojima, Kunihiko [Tohoku Univ., Sendai (Japan). Faculty of Agriculture; Ishii, Keizo

1994-12-31

37

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

Science.gov (United States)

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

Horita, Juske

1989-10-01

38

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 MgSO 4 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

39

Mutation rates at the glycophorin A and HPRT loci in uranium miners exposed to radon progeny.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVES--To find whether a relation exists between estimated levels of exposure to radon and its progeny and mutations in hypoxanthine phosphoribosyl transferase (HPRT) and glycophorin A in a cohort of former uranium miners. METHODS--A cohort study involving a sample of miners from the Radium Hill uranium mine in South Australia, which operated from 1952 to 1961. Radiation exposures underground at Radium Hill were estimated from historical radon gas measures with a job exposure matrix. Wor...

Shanahan, E. M.; Peterson, D.; Roxby, D.; Quintana, J.; Morely, A. A.; Woodward, A.

1996-01-01

40

Chest radiography in dust-exposed miners: Promise and problems, potential and imperfections  

International Nuclear Information System (INIS)

Since the early 1900s, it was recognized that many dust-exposed workers developed abnormal radiographs during life. Chest radiography remains the primary means of determining the presence and extent of dust-induced pneumoconiosis, although it is ineffective for detecting airways obstructions from mine dust exposure. This chapter reviews the uses and limitations of chest radiography in the study, surveillance, screening, clinical diagnosis, and disability determinations of occupational lung diseases in dust-exposed workers. 70 refs

1993-01-01

 
 
 
 
41

Mortality of a cohort of French uranium miners exposed to relatively low radon concentrations.  

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A cohort mortality study has been performed on French uranium miners having experienced more than 2 years of underground mining, with first radon exposure between 1946 and 1972. Vital status has been ascertained from the date of entry to the 31 December 1985 for 99% of the members of this cohort; causes of death are identified for 95.5% of the decedents. The different causes of death are compared to the age specific national death rates by indirect standardisation and expressed by standardise...

Tirmarche, M.; Raphalen, A.; Allin, F.; Chameaud, J.; Bredon, P.

1993-01-01

42

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

International Nuclear Information System (INIS)

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

1998-11-23

43

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

International Nuclear Information System (INIS)

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

1979-04-07

44

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

Science.gov (United States)

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

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

1988-02-01

45

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

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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 carrie...

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

2012-01-01

46

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-11-01

47

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

48

Synchrotron-based chemical nano-tomography of microbial cell-mineral aggregates in their natural, hydrated state.  

Science.gov (United States)

Chemical nano-tomography of microbial cells in their natural, hydrated state provides direct evidence of metabolic and chemical processes. Cells of the nitrate-reducing Acidovorax sp. strain BoFeN1 were cultured in the presence of ferrous iron. Bacterial reduction of nitrate causes precipitation of Fe(III)-(oxyhydr)oxides in the periplasm and in direct vicinity of the cells. Nanoliter aliquots of cell-suspension were injected into custom-designed sample holders wherein polyimide membranes collapse around the cells by capillary forces. The immobilized, hydrated cells were analyzed by synchrotron-based scanning transmission X-ray microscopy in combination with angle-scan tomography. This approach provides three-dimensional (3D) maps of the chemical species in the sample by employing their intrinsic near-edge X-ray absorption properties. The cells were scanned through the focus of a monochromatic soft X-ray beam at different, chemically specific X-ray energies to acquire projection images of their corresponding X-ray absorbance. Based on these images, chemical composition maps were then calculated. Acquiring projections at different tilt angles allowed for 3D reconstruction of the chemical composition. Our approach allows for 3D chemical mapping of hydrated samples and thus provides direct evidence for the localization of metabolic and chemical processes in situ. PMID:24548380

Schmid, Gregor; Zeitvogel, Fabian; Hao, Likai; Ingino, Pablo; Kuerner, Wolfgang; Dynes, James J; Karunakaran, Chithra; Wang, Jian; Lu, Yingshen; Ayers, Travis; Schietinger, Chuck; Hitchcock, Adam P; Obst, Martin

2014-04-01

49

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

50

New french uranium mineral species  

International Nuclear Information System (INIS)

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

1952-01-01

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.

1998-08-01

52

Minerals  

...Computers Cosmetics Crystals Dentistry Journal Diagnostics Diseases Diversity Econometrics Economies Education Sciences Electronics Energies Entropy Environments Fibers Foods Forests Future Internet Galaxies Games Genes ...Pathogens Pharmaceuticals Pharmaceutics Pharmacy Plants Polymers Processes Proteomes Publications Religions Remote Sensing Resources Risks Robotics Sensors Social Sciences Societies Sports Sustainability Symmetry Systems Technologies ... Kota Hanumantha Rao * Department of Civil, Environmental and Natural Resources Engineering, Division of Sustainable Process Engineering, Luleå University of Technology, ... Atanassova Department of Mineralogy and Mineral Resources, Geological Institute, Bulgarian Academy of Sciences, 24 Acad. Georgi Bonchev str.,...

53

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

International Nuclear Information System (INIS)

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

1997-11-01

54

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

55

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-30

56

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

Science.gov (United States)

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

Loladze, Irakli

2014-01-01

57

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

International Nuclear Information System (INIS)

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

2012-04-15

58

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-04-15

59

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

International Nuclear Information System (INIS)

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

1986-01-01

60

Chloral Hydrate  

Science.gov (United States)

Chloral hydrate, a sedative, is used in the short-term treatment of insomnia (to help you fall asleep and ... Chloral hydrate comes as a capsule and liquid to take by mouth and as a suppository to insert rectally. ...

 
 
 
 
61

Provenance of mineral phases in the Cretaceous-Tertiary boundary sediments exposed on the southern peninsula of Haiti  

Science.gov (United States)

Acid-insoluble mineral residua of tektite-bearing Cretaceous-Tertiary boundary sediments in the Beloc Formation of Haiti contain abundant shocked quartz and lesser amounts of shocked plagioclase. The shocked quartz grains typically have 2 or 3 sets of planar deformation features, although grains with up to 15 sets were observed. The proportion of shocked quartz in the boundary sediments increases with stratigraphic height; at least 70 +/- 11% of the proportion of the quartz grains are shocked in the uppermost stratigraphic interval. The proportion of shocked quartz throughout the boundary sediments indicates that these grains were excavated primarily from crystalline silicate units, which may have been covered with a small amount of porous quartz-bearing sediments. Polyhedral and moderately sutured margins in shocked polycrystalline quartz grains, the size of the crystal units in these grains and the presence of shocked plagioclase, indicate these ejecta components were excavated from a target with continental affinites, containing quartzites or metaquartzites and a sialic metamorphic and/or igneous component. Other evidence suggests the target may also have contained a significant amount of calcium carbonate and/or sulfate. The large size and amount of shocked quartz grains deposited in Haiti indicate the crater from which they were excavated was produced in the proto-Caribbean region.

Kring, David A.; Hildebrand, Alan R.; Boynton, William V.

1994-01-01

62

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

International Nuclear Information System (INIS)

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

2005-11-02

63

CO2 Injection in Hydrate Bearing Sandstone with Excess Water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

64

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

DEFF Research Database (Denmark)

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

Sonne, Christian; Wolkers, Hans

2008-01-01

65

Gas Hydrates  

International Nuclear Information System (INIS)

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

1996-01-01

66

DAN Active Parameters and Mastcam Hydration Survey Imaging: Comparisons Across Yellowknife Bay, Gale Crater, Mars  

Science.gov (United States)

The Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory (MSL) rover Curiosity has recorded variability in neutron counts along traverses in and around Yellowknife Bay that suggest variable amounts of hydrogen (H) are present. At the locations of several DAN observations, Mastcam 'hydration survey' mosaics have been acquired with the R0 (493 nm, 551 nm and 638 nm), R5 (937 nm) and R6 (1013 nm) science filters to characterize RGB color and look for potential hydration as indicated by an absorption near 1000 nm. Whereas DAN is sensitive to H abundance down to 60cm depth, the Mastcam hydration index is sensitive to the presence of certain hydrated minerals (bound-OH and/or H2O) exposed in the upper hundreds of micrometers of the surface. Furthermore, many light-toned, Ca-sulfate-bearing features (i.e. veins and nodules within the outcrop) exposed at the surface in Yellowknife Bay have a high hydration index, consistent with a hydrated mineral such as gypsum. Other light-toned features do not have a high hydration index, suggesting they are composed of anhydrous or lower hydration state phases such as anhydrite or bassanite. The distribution of light-toned features within the outcrop at Yellowknife Bay is also highly variable within a DAN footprint. Given that there is variability in both the DAN signal and Mastcam hydration index throughout Yellowknife Bay, this work investigates whether or not increases or decreases in H seen by DAN correlate to areas of high hydration index as derived from Mastcam observations. Positive correlations of the DAN H signal and Mastcam hydration index may indicate that the observed densities of light-toned features (hydrated or dehydrated) extend to at least 60cm depth. Conversely, negative correlations could indicate that either the veins/nodules are only present at very shallow depths (a few cm), that the hydration of the phases changes with depth (e.g., gypsum at the surface and anhydrite at depth), or that there is a buried layer of H-rich material more strongly influencing the DAN signal. Through modeling of a variety of layer geometries and H-rich layers, we investigate whether a one- or two-layer model more accurately fits the DAN data as well as the amount of H within each layer. As of sol 269, DAN has acquired over 30 active measurements while Curiosity made her way to the location of where the first and second drill holes would be made, including measurements at those sites. Over 100 Mastcam hydration survey observations within Yellowknife Bay have been acquired, primarily at the drill sites. We will present the results of detailed mapping of the veins and nodules within the Mastcam hydration surveys in Yellowknife Bay to determine if the DAN signal can be correlated or anti-correlated to the surficial spatial distribution of these features. Where data from other instruments like APXS or ChemCam are available to constrain the H or Cl abundance at the location of a given DAN active measurement, and if those compositions are assumed to be laterally homogeneous within the DAN footprint, they can be used to constrain the modeled surface compositions to determine how deep the surface composition extends.

Hardgrove, C. J.; Rice, M. S.; Moersch, J.; Mitrofanov, I. G.; Litvak, M.; Wellington, D. F.; Behar, A.; Bell, J. F.; Boynton, W. V.; DeFlores, L.; Drake, D.; Fedosov, F.; Golovin, D.; Jun, I.; Harshman, K.; Kozyrev, A.; Malakhov, A.; Milliken, R.; Kuzmin, R.; Mischna, M. A.; Mokrousov, M.; Nikiforov, S.; Sanin, A.; Tate, C.; Team, M.

2013-12-01

67

New french uranium mineral species; Nouvelles especes uraniferes francaises  

Energy Technology Data Exchange (ETDEWEB)

In this work, the authors study the french new uranium minerals: parsonsite and renardite, hydrated phosphates of lead and uranium; kasolite: silicate hydrated of uranium and lead uranopilite: sulphate of uranium hydrated; bayleyite: carbonate of uranium and of hydrated magnesium; {beta} uranolite: silicate of uranium and of calcium hydrated. For all these minerals, the authors give the crystallographic, optic characters, and the quantitative chemical analyses. On the other hand, the following species, very rare in the french lodgings, didn't permit to do quantitative analyses. These are: the lanthinite: hydrated uranate oxide; the {alpha} uranotile: silicate of uranium and of calcium hydrated; the bassetite: uranium phosphate and of hydrated iron; the hosphuranylite: hydrated uranium phosphate; the becquerelite: hydrated uranium oxide; the curite: oxide of uranium and lead hydrated. Finally, the authors present at the end of this survey a primary mineral: the brannerite, complex of uranium titanate. (author) [French] Dans ce travail, les auteurs etudient les nouveaux mineraux uraniferes francais: parsonsite et renardite, phosphates hydrates de plomb et d'uranium; kasolite: silicate hydrate d'uranium et de plomb uranopilite: sulfate d'uranium hydrate; bayleyite: carbonate d'uranium et de magnesium hydrate; {beta} uranolite: silicate d'uranium et de calcium hydrate. Pour tous ces mineraux, les auteurs donnent les caracteres cristallographiques, optiques, et les analyses chimiques quantitatives. Par contre, les especes suivantes, tres rares dans les gites francais, n'ont pas permis d'effectuer d'analyses quantitatives. Ce sont: l'ianthinite: oxyde uraneux hydrate; l'{alpha} uranotile: silicate d'uranium et de calcium hydrate; le bassetite: phosphate d'uranium et de fer hydrate; la hosphuranylite: phosphate duranium hydrate; la becquerelite: oxyde d'uranium hydrate; la curite: oxyde d'uranium et de plomb hydrate. Enfin, les auteurs presentent a la fin de cette etude un mineral primaire: la brannerite, titanate d'uranium complexe. (auteur)

Branche, G.; Chervet, J.; Guillemin, C. [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1952-07-01

68

The Behavior of Hydrated Na-Mg Sulfate Phases Under Mars-Relevant Conditions  

Science.gov (United States)

An increasing inventory of hydrous evaporite and silicate minerals has been identified from orbital and lander data on Mars. Several hydrous sulfate minerals are thought to be present on Mars, based on spectral, chemical, and geomorphic observations (e.g., CRISM, OMEGA, and Mars Exploration Rover results). We are examining the behavior of hydrous minerals on Mars and their potential participation in the H2O cycle to augment and complement these data. With limited liquid water stability on the martian surface, hydration and dehydration of hydrous minerals with changes in temperature (T) and relative humidity (RH) during a Mars day can have a significant influence on the bioavailability of water and potentially on atmospheric H2O. This research focused on the Na2MgSO4nH2O system, predicted by King et al. (2004) to occur on Mars. Phases in this system were also predicted by Clark et al. (1981), based on the concentration of Mg on Mars' surface. They proposed that Mg would be more stable in the form of a double salt, as a result of solubilities in the MgSO4nH2O system. Our experiments included blödite, konyaite, a decahydrate, and potential new phases. Blödite (Na2MgSO44H2O) was analyzed by X-ray powder diffraction (XRD) under controlled RH-T conditions to investigate its behavior and to understand mineral reactions. Crystal structures and phase abundances were determined using Rietveld methods. When blödite was allowed to deliquesce (RH>80%) and then exposed to low temperatures (Tsodium sulfate under lower-RH conditions in association with epsomite. This separation occurred for dry and wet blodite, implying that time is the key factor in determining the low-T assemblage. The result of the first experiment was apparently a metastable phase, based on its rapid formation and its ultimate transformation to a two-phase mixture. Meridianiite and mirabilite, and likely the new hydrate, contain more H2O by weight than the highest known hydrate of Na2MgSO4 (the decahydrate, 41 wt% H2O). Depending on the abundance of water, Na-Mg sulfate solutions have the potential to precipitate several different highly hydrated phases, all of which undergo dehydration/hydration reactions on heating/cooling. Thus, these phases add to the list of hydrated phases on the martian surface that can participate in the H2O cycle and contribute to the mineral H2O storage inventory.

Leftwich, K.; Bish, D. L.

2012-12-01

69

Hydrated Sulfates in the Southern High Latitudes of Mars  

Science.gov (United States)

Sulfates on Mars appear largely concentrated in sedimentary rocks dating to the Late Noachian or Hesperian [e.g., 1], but they are also abundant in Amazonian sand dunes around the north polar cap [2]. The gypsum in those dunes derives from the polar layered deposits [e.g., 3], where it may form when sunlight causes minor melting and weathering of embedded dust. We are investigating whether such processes might have also contributed to sulfate formation elsewhere, specifically in regions surrounding the south polar terrain. Our study regions to date include the Sisyphi Montes (20W-40E and 55-75S) and other mountainous areas near the Thyles Rupes (110-140E and 55-75S), the Ulyxis Rupes (150-180E and 55-70S), and Chamberlin Crater (110-150W and 55-75S). We searched for sulfates using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). TRR3 images were evaluated using standard CRISM procedures, including the "volcano scan" atmospheric correction. We used spectral parameters to identify regions of interest, from which we extracted spectra, which we divided by spectrally neutral regions in the same scene to remove systematic artifacts. The resulting ratio spectra were visually compared to library spectra to identify possible hydrated mineral constituents. Some sulfates in the southern high latitudes appear localized to mountains of the Sisyphi Montes, which have been interpreted as volcanoes that erupted under a Hesperian ice sheet [4]. These sulfates might have formed via volcanic hydrothermal or acid fog alteration. We found that nearly 50% of the images on putative volcanoes in the Sisyphi Montes show a 1.9 ?m absorption consistent with hydration. The percentage for images on the plains between volcanoes is actually higher; i.e., hydration is not unique to the volcanoes. Nevertheless, the three locations at which we found the strongest absorptions are all on volcanoes. In the Thyles Rupes region, 25% of the images on putative volcanoes are hydrated with a broad band at ~1.92 ?m. Roughly 45% of the images off volcanoes are hydrated with the majority of them being located inside a crater, on a crater rim, or in the plains. Nearly 80% of hydrated images near the Ulyxis Rupes are also located either on a crater rim or inside a crater. Twenty percent of the images near the Chamberlin Crater are hydrated and mostly located in the plains or on a crater rim. Their spectra show consistent absorptions around 1.9 and 2.5 ?m. The concentration of hydrated sulfates inside and on the rims of craters in all three of these regions suggests that the sulfates may be relatively old, and were exposed when the surface was impacted. Our results substantially expand the number of known areas in the southern high latitudes exhibiting hydration. The fact that hydration is found in all the regions we studied suggests an ubiquitous process for hydrated mineral formation, possibly similar to icy weathering processes proposed for the north polar region. References: [1] Bibring J.-P. et al. (2006) Science, 312, 400-404. [2] Langevin Y. et al. (2005) Science, 307, 1584-1586. [3] Massé M. et al. (2010) Icarus, 209, 434-451. [4] Ghatan G. and Head J. (2002) JGR, 107, 5048

Ackiss, S. E.; Wray, J. J.

2012-12-01

70

CO2 Injection in Hydrate Bearing Sandstone with Excess Water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

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

1996-06-01

72

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

73

Hydration Solution for Injection  

Science.gov (United States)

Your doctor has ordered an intravenous hydration solution for injection. Hydration solution is used for patients who cannot or should not get fluids through drinking and eating. The hydration solution will ...

74

Investigations into surfactant/gas hydrate relationship  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-03-15

75

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

Scientific Electronic Library Online (English)

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

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

76

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

Science.gov (United States)

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

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

2008-12-01

77

Gas hydrate contribution to Late Permian global warming  

Science.gov (United States)

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

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

2014-05-01

78

Mineral nutrient imbalance, DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L. seedlings exposed to lanthanum ions.  

Science.gov (United States)

Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K+) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth. PMID:22655379

Wang, Chengrun; Zhang, Kegui; He, Mei; Jiang, Chuanjun; Tian, Liumin; Tian, Yuan; Wang, Xiaorong

2012-01-01

79

Cyclopentane Hydrate for Hydrate Wetting Studies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Abdulkader, Bashir Mohammed Hissen

2013-01-01

80

Cyclopentane Hydrate for Hydrate Wetting Studies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

 
 
 
 
81

The hydratation of tertiary acetylene glycerin  

International Nuclear Information System (INIS)

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

1961-01-01

82

Dehydration of synthetic autunite hydrates  

International Nuclear Information System (INIS)

The dehydration of uranyl minerals can affect phase structure and stability. Synthetic autunite hydrates, Ca[(UO2)(PO4)]2.xH2O, were studied by X-ray powder diffractometry (XRD) and thermogravimetric analysis (TGA) to address ambiguous or contradictory reports in the literature. Structurally, XRD analysis supported the three well-defined phases commonly reported in the literature, i.e. autunite, metaautunite I, and metaautunite II. In addition, a fourth phase with a basal plane spacing between that of autunite and metaautunite I, designated metaautunite Ia, was identified as an apparent metastable intermediate. TGA analysis confirmed that water loss or accumulation is tolerated to different degrees among the autunite hydrates. Loss of low temperature water appears to initiate collapse of the interlayer spacing from 10 to 9 A to form metaautunite I and/or Ia, while the lower hydrates accommodate minor water loss and accumulation without significant structural alteration. Our results support previous research indicating the reversibility of the autunite to metaautunite I conversion. The complex dehydration pattern of autunite is not observed in all the 1:1 uranyl phosphates, such as chernikovite (H[(UO2)(PO4)].4H2O). (orig.)

2000-01-01

83

Dehydration of synthetic autunite hydrates  

Energy Technology Data Exchange (ETDEWEB)

The dehydration of uranyl minerals can affect phase structure and stability. Synthetic autunite hydrates, Ca[(UO{sub 2})(PO{sub 4})]{sub 2}.xH{sub 2}O, were studied by X-ray powder diffractometry (XRD) and thermogravimetric analysis (TGA) to address ambiguous or contradictory reports in the literature. Structurally, XRD analysis supported the three well-defined phases commonly reported in the literature, i.e. autunite, metaautunite I, and metaautunite II. In addition, a fourth phase with a basal plane spacing between that of autunite and metaautunite I, designated metaautunite Ia, was identified as an apparent metastable intermediate. TGA analysis confirmed that water loss or accumulation is tolerated to different degrees among the autunite hydrates. Loss of low temperature water appears to initiate collapse of the interlayer spacing from 10 to 9 A to form metaautunite I and/or Ia, while the lower hydrates accommodate minor water loss and accumulation without significant structural alteration. Our results support previous research indicating the reversibility of the autunite to metaautunite I conversion. The complex dehydration pattern of autunite is not observed in all the 1:1 uranyl phosphates, such as chernikovite (H[(UO{sub 2})(PO{sub 4})].4H{sub 2}O). (orig.)

Sowder, A.G. [Savannah River Ecology Lab., Aiken, SC (United States); Clark, S.B. [Washington State Univ., Pullman, WA (United States). Dept. of Chemistry; Fjeld, R.A. [Clemson Univ., SC (United States). Dept. of Environmental Eng. and Sci.

2000-07-01

84

Experimental study on sorption of actinides onto hydrated cementitious materials. Effect of alteration of cement hydrates by dissolution  

International Nuclear Information System (INIS)

Cementitious material is a potential waste packaging and backfilling material for the radioactive waste disposal, and is expected to provide both physical and chemical containment. In particular, the sorption of radionuclides onto cementitious material is a very important parameter when considering the release of radionuclides from radioactive wastes. In this study, sorption of thorium and neptunium onto hydrated Ordinary Portland Cement (OPC) and Highly containing Flyash and Silicafume Cement (HFSC) was measured. For thorium and neptunium sorption onto hydrated OPC and HFSC, the obtained distribution ratios, Rd values, are very high: > 1E+03 cm3g-1. Once the composition or crystallinity of the constituent minerals of a cementitious material is changed by alteration in the disposal environment, its sorption ability might be affected. So leaching experiments for OPC and HFSC hydrates were carried out to provide altered cement hydrate samples, followed by sorption experiments of thorium and neptunium onto these to investigate the effect of alteration of cement on sorption. In the leaching experiments, portlandite, which is a constituent mineral of hydrated OPC, was dissolved, and the specific surface area of both OPC and HFSC hydrates was increased by alteration. In the thorium and neptunium sorption experiments, the distribution ratio for altered OPC and HFSC hydrates was higher than freshly cured (unaltered) hydrated cement samples, which appear to be due to the increase of the specific surface area of those. These results show that the alteration of cement hydrates by dissolution of constituent minerals does not cause changes which could decrease the sorption of thorium and neptunium onto hydrated OPC and HFSC. (author)

2000-05-01

85

Gas hydrate and humans  

Science.gov (United States)

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

Kvenvolden, K. A.

2000-01-01

86

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

87

EFFECT OF ORGANIC AND INORGANIC MINERAL SUPPLEMENTATION ON SEMINAL QUALITY OF BOARS EXPOSED TO HEAT STRESS EFEITO DA SUPLEMENTAÇÃO DE MINERAIS ORGÂNICOS E INORGÂNICOS NA QUALIDADE DO SÊMEN DE SUÍNOS SUBMETIDOS A ESTRESSE TÉRMICO  

Directory of Open Access Journals (Sweden)

Full Text Available

Seasonal high temperatures or inadequate nutrition can decrease reproductive efficiency in boars, especially through a reduction in spermatozoal number / ejaculate and percentage of normal spermatozoa. The aim of this study was to evaluate the effect of organic and inorganic trace mineral supplementation on seminal quality in boars exposed to high environmental temperatures. The experiment was conducted in Southern Brazil, west of Parana State. Boars (2 years of age were divided into three groups to receive: inorganic (GIn, n=4 and organic (GOr, n=4 mineral supplementation and a lactation diet (GCo, n=5. Inorganic and organic diets contained a premix of inorganic and organic trace minerals, respectively, with the same quantity of each trace mineral, based on NRC (NRC, 1998 for boars. The lactation diet was based on NRC for lactating sows and contained a higher level of inorganic trace minerals, protein and metabolic energy. Maximum mean environmental temperatures were higher than the normal thermal comfort temperature for boars (26oC during the experimental period, and were associated with a reduction in semen quality. Results are expressed as mean ± SEM. The semen volume of Inorganic and Organic diet groups were higher than Lactation group animals (345.7 ± 92.6 mL and 338.4 ± 67.8 mL versus 302.5 ± 81.4 mL, respectively; P=0.02. Boars in the Organic diet group had higher sperm concentration when compared to the Inorganic diet group (233.5 ± 76.7 X 106 sptz/mL versus 181.2 ± 77.3 X 106 sptz/mL, respectively; P=0.006. Percentage of normal spermatozoa, averaged higher in the Organic group than both Inorganic and Lactation groups (93.31 ± 5.20% versus 78.48 ± 12.15% and 82.59 ± 17.27%, respectively; P=0.00021. High temperatures (>34.5 oC reduced normal spermatozoa number in all groups, but with significant differences only in the Inorganic and Lactation groups (P=0.03. Organic minerals were benefic to seminal quality, reducing some of the heat stress effects in exposed boars.

KEY WORDS: Heat stress, organic minerals, semen, swine.
Estações de elevadas temperaturas ou nutrição inadequada podem influenciar a eficiência reprodutiva de machos suínos, especialmente através da redução no número de espermatozoides ejaculados e da porcentagem de espermatozoides normais. O objetivo deste trabalho foi avaliar o efeito da suplementação micromineral orgânica e inorgânica sobre a qualidade do sêmen de suínos expostos à elevada temperatura ambiental. O experimento foi realizado na Região Sul do Brasil, no oeste do Paraná. Machos de dois anos de idade foram divididos em três grupos para receber: suplementação mineral inorgânica (GIn, n=4, orgânica (GOr, n=4 e uma dieta lactação (GCo, n=5. Dietas inorgânicas e orgânicas continham um premix de microminerais inorgânicos e orgânicos, respectivamente, com a mesma quantidade de cada micromineral, baseado no NRC para machos suínos. A dieta lactação baseou-se no NRC para fêmeas em lactação e continha um nível superior de microminerais inorgânicos, proteínas e energia metabólica. A média de temperatura ambiental máxima foi superior à temperatura normal de conforto térmico para machos suínos (26 ºC durante todo o período experimental, e foi associada com uma redução na qualidade seminal. Os resultados foram expressos como média ± EPM. O volume de sêmen dos grupos de dieta inorgânica e orgânica foi maior do que nos animais do grupo lactação (345,7 ± 92,6 mL e 338,4 ± 67,8 mL contra 302,5 ± 81,4 mL, respectivamente; P=0,02. Machos no grupo de dieta orgânica apresentaram uma maior concentração espermática quando comparados ao grupo de dieta inorgânica (233,5 ± 76,7 X 106 sptz/mL contra 181,2 ± 77,3 X 106 sptz/mL, respectivamente; P=0,006. A porcentagem de espermatozoides normais foi maior no grupo orgânico do que em ambos os grupos inorgânico e lactação (93,31 ± 5,20% contra 78,48 ± 12,15% e 82,59 ± 17,27%, r

Daiane Donin Spessatto

2009-12-01

88

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

89

Combustion of Methane Hydrate  

Science.gov (United States)

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

Roshandell, Melika

90

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

1993-09-26

91

Methane Hydrate Field Program  

Energy Technology Data Exchange (ETDEWEB)

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

None

2013-12-31

92

Gas hydrate nucleation  

Energy Technology Data Exchange (ETDEWEB)

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

NONE

1997-12-31

93

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

94

High-pressure gas hydrates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2008-01-01

95

Calcium Aluminate Cement Hydration Model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 exam...

2011-01-01

96

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

97

Uruguay minerals fuels  

International Nuclear Information System (INIS)

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

1967-01-01

98

Evaluation of Hydrated Lime Filler in Asphalt Mixtures  

Directory of Open Access Journals (Sweden)

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

Mohammed Abbas Hasan Al-Jumaily

2008-01-01

99

Hydrated vanadium pentoxide  

International Nuclear Information System (INIS)

Production methods; solubility; ion-exchange, thermal and other physico-chemical properties of hydrated vanadium pentoxide, alkali and alkaline earth metal and V_2O_5 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 V_2O_5 is discussed on the basis of analysis of new results of studying the structure and properties

1986-01-01

100

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

 
 
 
 
101

Modelling porewater chemistry in hydrated Portland cement  

International Nuclear Information System (INIS)

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

1987-01-01

102

Compressibility of gas hydrates.  

Science.gov (United States)

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

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

2011-09-12

103

Hydration of black carbon  

Science.gov (United States)

Hydration studies of n-hexane soot particles in the relative H2O pressure range 0.33-0.52 have revealed the nature of the processes between water molecules in the vapor phase and primary reaction sites at the particle surface. Initially, about 40% of the carbon-oxygen functionalities (most likely the carboxylics) on freshly prepared soot reacts irreversibly with water vapor, while at P/Po ? 0.48, the adsorption follows the Dubinin-Radushkevich equation. Determination of these parameters enables calculation of surface coverage at limiting adsorption and at the chemisorption limit for all materials studied. Limiting surface coverage of fresh soot is consistent with a 50% oxygen coverage determined earlier; it increases to about 100% for nitrated soot, which is the most extensively hydrated. Hydration has been shown to increase with soot aging, a phenomenon which has revealed an important role of physisorbed O2 in hydration. Trace-metal incorporation at the 30-110 ppm level significantly increases particle hydration and demonstrates a role of metal centers in the process.

Chughtai, A. R.; Brooks, M. E.; Smith, D. M.

1996-08-01

104

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

Science.gov (United States)

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

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

1999-01-01

105

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

Science.gov (United States)

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

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

2011-10-01

106

Gas Hydrates: It's A Gas!  

Science.gov (United States)

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

107

A new clathrate hydrate structure  

International Nuclear Information System (INIS)

On the basis of "2H and "1"2"9Xe NMR measurements and X-ray and neutron powder diffraction results, the authors report a new hexagonal hydrate structure requiring both large and small guest molecules to stabilize the structure. This hydrate is expected to be isostructural with the hexagonal clathrasil dodecasil-1H. As for the cubic clathrate hydrates, the new hydrate structure may occur naturally. (author)

1987-01-08

108

Mineral Properties  

Science.gov (United States)

You will learn about the properties that will help you identify minerals. If you closed your eyes and tasted different foods, you could probably determine what the foods are by noting properties such as saltiness or sweetness. You can also determine the identity of a mineral by noting different properties. Some properties that help us determine the identy of a mineral are: COLOR, ...

Wood, Mr.

2010-11-14

109

Mineral Chart  

Science.gov (United States)

... Tanning How Can I Improve My Self-Esteem? Mineral Chart KidsHealth > Teens > Miscellaneous > Mineral Chart Print A A A Text Size Type ... sources of calcium. You'll also find this mineral in broccoli and dark green, leafy vegetables. Soy ...

110

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

Science.gov (United States)

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

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

2009-12-01

111

Wet hydrate dissolution plant  

Directory of Open Access Journals (Sweden)

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

Stankovi? Mirjana S.

2003-01-01

113

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

Science.gov (United States)

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

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

2013-04-01

114

Electronic structure calculations of calcium silicate hydrates  

International Nuclear Information System (INIS)

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

1995-12-01

115

Electronic structure calculations of calcium silicate hydrates  

Energy Technology Data Exchange (ETDEWEB)

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

Sterne, P.A. [Univ. of California, Davis, CA (United States). Dept. of Physics]|[Lawrence Livermore National Lab., CA (United States); Meike, A. [Lawrence Livermore National Lab., CA (United States)

1995-11-01

116

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

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

Mineral Identification  

Science.gov (United States)

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

Pratte, John

119

Evolution of iron speciation during hydration of C4AF.  

Science.gov (United States)

It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C4AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C4AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C4AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C4AF forms C3AH6 (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C3AH6; iron does not seem to be incorporated in the AFm structure. PMID:16697177

Rose, J; Bénard, A; El Mrabet, S; Masion, A; Moulin, I; Briois, V; Olivi, L; Bottero, J-Y

2006-01-01

120

Animated molecular dynamics simulations of hydrated Cesium-smectite interlayers  

International Nuclear Information System (INIS)

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

2002-01-01

 
 
 
 
121

Hydration of lithium ?-alumina  

International Nuclear Information System (INIS)

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 H_2O concentrations in the conduction plane can be carried continuously and reversibly up to a saturation limit of about 1.8 H_2O 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 H_2O 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"-, H_3O"+ and H_5O"+_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

122

Carbonaceous particle hydration  

Science.gov (United States)

Microgravimetric measurements of the hydration of several different black carbons or soots and a series of commercial carbon blacks have been carried out, over a relative humidity range of 20-85%, in an extension of earlier work with the model n-hexane soot. All adsorption isotherms are of type III and were analyzed by the use of the Dubinin-Radushkevich (DR) equation which, although applicable over a limited range of intermediate relative humidity values, allows identification of chemisorption limit and onset of multilayer formation. While surface area determines the maximum adsorption possible for a given type, surface functionalities are determinative at lower humidity and are characteristic of the soot-producing fuel. Aging of carbon particles and oxygen chemisorption as well as O 2 physisorption strongly influence the extent of hydration for those soots studied, such as JP-8 aviation and diesel fuels. Infrared spectra confirm the surface oxidation of JP-8 soot by its reaction with O 3, a reaction of probable atmospheric importance, as underlying its increased hydration.

Chughtai, A. R.; Williams, G. R.; Atteya, M. M. O.; Miller, N. J.; Smith, D. M.

123

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

2013-10-01

124

Rapid gas hydrate formation process  

Science.gov (United States)

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

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

2013-01-15

125

Global occurrences of gas hydrate  

Science.gov (United States)

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

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

2001-01-01

126

Acid-catalyzed hydration of alkynes in aqueous microemulsions.  

Science.gov (United States)

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. PMID:23401485

Nairoukh, Zackaria; Avnir, David; Blum, Jochanan

2013-03-01

127

Animated molecular dynamics simulations of hydrated caesium-smectite interlayers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 o...

2002-01-01

128

Gas hydrate cool storage system  

Science.gov (United States)

The invention presented relates to the development of a process utilizing a gas hydrate as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas hydrate as storage material in a thermal energy storage system within a heat pump cycle system. The gas hydrate was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)

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

1984-09-12

129

Hydrate Monitoring using Capacitive Sensors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

130

Mineral Identification  

Science.gov (United States)

In this activity, students use written and online materials to answer a set of questions on the general properties and identification of minerals. They will learn about physical properties such as color, hardness, and cleavage; special properties such as fluorescence and effervescence; and complete a chart listing properties for a selection of minerals. Links to the necessary information are provided.

Passow, Michael

131

Mineral Densities  

Science.gov (United States)

Students are given cubic cell edge dimensions and asked to calculate mineral densities and vice versa. The final question of this homework assignment provides students with a mineral density and unit cell edge length in order to determine the number of formula units per cell.

132

New observations and insights into the morphology and growth kinetics of hydrate films.  

Science.gov (United States)

The kinetics of film growth of hydrates of methane, ethane, and methane-ethane mixtures were studied by exposing a single gas bubble to water. The morphologies, lateral growth rates, and thicknesses of the hydrate films were measured for various gas compositions and degrees of subcooling. A variety of hydrate film textures was revealed. The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film. A clear relationship between the morphology and film growth kinetics was observed. The shape of the hydrate crystals was found to favour heat or mass transfer and favour further growth of the hydrate film. The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6. PMID:24549241

Li, Sheng-Li; Sun, Chang-Yu; Liu, Bei; Li, Zhi-Yun; Chen, Guang-Jin; Sum, Amadeu K

2014-01-01

133

High-pressure gas hydrates.  

Science.gov (United States)

It has long been known that crystalline hydrates are formed by many simple gases that do not interact strongly with water, and in most cases the gas molecules or atoms occupy 'cages' formed by a framework of water molecules. The majority of these gas hydrates adopt one of two cubic cage structures and are called clathrate hydrates. Notable exceptions are hydrogen and helium which form 'exotic' hydrates with structures based on ice structures, rather than clathrate hydrates, even at low pressures. Clathrate hydrates have been extensively studied because they occur widely in nature, have important industrial applications, and provide insight into water-guest hydrophobic interactions. Until recently, the expectation-based on calculations-had been that all clathrate hydrates were dissociated into ice and gas by the application of pressures of 1 GPa or so. However, over the past five years, studies have shown that this view is incorrect. Instead, all the systems so far studied undergo structural rearrangement to other, new types of hydrate structure that remain stable to much higher pressures than had been thought possible. In this paper we review work on gas hydrates at pressures above 0.5 GPa, identify common trends in transformations and structures, and note areas of uncertainty where further work is needed. PMID:18259632

Loveday, J S; Nelmes, R J

2008-02-21

134

Stability of DNA thymine hydrates.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pyrimidine hydrates are products of ultraviolet irradiation of DNA. We have already demonstrated the formation of both cis-thymine hydrate and trans-thymine hydrate (6-hydroxy-5,6-dihydrothymine) in irradiated poly(dA-dT):poly(dA-dT). These are released from DNA as free bases by bacterial or human glycosylases. Thymine hydrate stabilities were studied in irradiated DNA substrates using purified E. coli endonuclease III as a reagent for their removal. After irradiation, substrate poly(dA-dT):p...

1991-01-01

135

Seismic reflections associated with submarine gas hydrates.  

Science.gov (United States)

Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom ...

K. Andreassen

1995-01-01

136

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

137

Crowding induced collective hydration of biological macromolecules over extended distances.  

Science.gov (United States)

Ultrafast two-dimensional infrared (2D-IR) spectroscopy reveals picosecond protein and hydration dynamics of crowded hen egg white lysozyme (HEWL) labeled with a metal-carbonyl vibrational probe covalently attached to a solvent accessible His residue. HEWL is systematically crowded alternatively with polyethylene glycol (PEG) or excess lysozyme in order to distinguish the chemically inert polymer from the complex electrostatic profile of the protein crowder. The results are threefold: (1) A sharp dynamical jamming-like transition is observed in the picosecond protein and hydration dynamics that is attributed to an independent-to-collective hydration transition induced by macromolecular crowding that slows the hydration dynamics up to an order of magnitude relative to bulk water. (2) The interprotein distance at which the transition occurs suggests collective hydration of proteins over distances of 30-40 Å. (3) Comparing the crowding effects of PEG400 to our previously reported experiments using glycerol exposes fundamental differences between small and macromolecular crowding agents. PMID:24341684

King, John T; Arthur, Evan J; Brooks, Charles L; Kubarych, Kevin J

2014-01-01

138

Ripper miner  

Energy Technology Data Exchange (ETDEWEB)

A low cost, energy efficient, continuous mechanical cutting head which uses a single large cutter and can excavate rectangular openings of different sizes in a wide variety of rocks and face conditions has been developed. Laboratory testing of the ripper miner has been conducted on both a small and a large scale. The ripper miner is capable of cutting almost all materials, but is best suited for soft and medium strength rocks such as limestone, sandstone, and shale.

1987-11-01

139

Animated molecular dynamics simulations of hydrated caesium-smectite interlayers  

Directory of Open Access Journals (Sweden)

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

Sposito Garrison

2002-09-01

140

Animated molecular dynamics simulations of hydrated caesium-smectite interlayers  

Science.gov (United States)

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

 
 
 
 
141

Clay Minerals  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-03-14

142

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

143

Moessbauer study of hydrated iron sulfates  

International Nuclear Information System (INIS)

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

1991-01-01

144

Oxidants from Pulverized Minerals  

Science.gov (United States)

Joel Hurowitz (previously at State University of New York at Stony Brook and now at the Jet Propulsion Laboratory), Nick Tosca, Scott McLennan, and Martin Schoonen (SUNY at Stony Brook) studied the production of hydrogen peroxide from freshly pulverized minerals in solution. Their experiments focused on olivine, augite, and labradorite; silicate minerals of basaltic planetary surfaces, such as the Moon and Mars, that are exposed to the intense crushing and grinding of impact cratering processes. The hydrogen peroxide produced in the experiments was enough to adequately explain the oxidizing nature of Martian regolith first determined by the Viking Landers and the results suggest, for the first time, that mechanically activated mineral surfaces may be an important part of the overall explanation for the Viking Lander biology experiment results. Hurowitz and coauthors further showed that when the pulverized minerals are heat-treated to high temperature under vacuum (to cause dehydroxylation) there is almost a 20 times increase in hydrogen peroxide production, a result which may be highly relevant to lunar dust. These careful studies demonstrate the importance of and concern about reactive dusts on planetary surfaces from two standpoints: the health of astronauts on surface maneuvers who may inadvertently breath it and the viability of possible Martian organic species to survive in such a corrosive, antiseptic surface environment.

Martel, L. M. V.

2007-06-01

145

Norwegian Research Strategies on gas Hydrates and Natural Seeps in the Nordic Seas Region (GANS)  

Science.gov (United States)

Continuous leakage of methane to the oceans from hydrate reservoirs that partially are exposed towards the seafloor is an increasing international concern, as the greenhouse gas methane is significantly more (c. 20 times) aggressive than CO2. In Norway we have research groups with interest and experience on natural seeps and gas hydrates. These features, and processes related to them, are challenging research targets which demands inputs from different fields if important research breakthroughs shall be made. In February 2004 deep sea researchers from the University of Tromso, Geological Survey of Norway, Norwegian Geotechnical Institute, Statoil and University of Bergen met to obtain an overview of the research effort in the fields of natural seeps and gas hydrates in Norway and to discuss national coordination, research strategies, research infrastructure and international co-operation. The following research strategies were agreed upon: i) Strengthen multidisciplinary research on deep sea systems, ii) develop a strategy for research on natural seeps and gas hydrates, iii) contribute in national coordination of research on natural seeps and gas hydrates, iv) Coordinate the use and development of research infrastructures important for research on natural seeps and gas hydrates, and v) contribute in the international evaluations of strategies for hydrate reservoir exploitation. Proposed research tasks for GANS include: i) Gas and gas hydrate formation processes and conditions for transport, accumulation, preservation and dissociation in sediments, ii) Effect of gas hydrate on physical properties of sediment, iii) Detection and quantification of in situ gas hydrate content and distribution pattern, iv) Effect of dissociation on soil properties, v) Gas hydrates as an energy resource, vi) Rapid methane release and climate change, and vii) Geohazard and environmental impact.

Hjelstuen, B. O.; Sejrup, H. P.; Andreassen, K.; Boe, R.; Eldholm, O.; Hovland, M.; Knies, J.; Kvalstad, T.; Kvamme, B.; Mienert, J.; Pedersen, R. B.

2004-12-01

146

Structural studies of gas hydrates  

International Nuclear Information System (INIS)

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

2002-01-01

147

Hydration of alite containing alumimium  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

148

Gas Hydrates: It's a Gas  

Science.gov (United States)

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

149

Energy storage by salt hydration  

Energy Technology Data Exchange (ETDEWEB)

A process and apparatus for energy storage wherein thermal energy from solar or waste heat derived sources is passed in thermal exchange relation with a hydrated inorganic salt, such as calcium sulfate, endothermically dehydrating the salt thereby storing chemical energy and releasing the stored energy as heat by passing water under hydration conditions in contact with the salt exothermically hydrating the salt. The released thermal energy is substantially isothermal and available for any desired use involving thermal energy input. The process and apparatus of this invention is particularly suited to utilization of solar derived thermal energy.

Pangborn, J.B.

1981-12-01

150

Mineral sands  

International Nuclear Information System (INIS)

This paper presents an outlook of the Australian mineral sand industry and covers the major operators. It is shown that conscious of an environmentally minded public, the Australian miners have led the way in the rehabilitation of mined areas. Moreover the advanced ceramic industry is generating exciting new perspectives for zircon producers and there is a noticeable growth in the electronic market for rare earths, but in long term the success may depend as much on environmental management and communication skills as on mining and processing skills

1990-01-01

151

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

Science.gov (United States)

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

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

2013-12-01

152

Mineral transportation  

Energy Technology Data Exchange (ETDEWEB)

Rail transport, the west coast ports, the transportation infra-structure in northern Canada, the St. Lawrence Seaway, Arctic shipping, and international shipping and expansion plans in these areas are described as they pertain to Canada's mineral transportation.

Bokavay, G.A.; Ebrahim, A.

1983-02-01

153

Perspectives on Hydrate Thermal Conductivity  

Directory of Open Access Journals (Sweden)

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

Niall J. English

2010-12-01

154

Heavily Hydrated Salts on Europa  

Science.gov (United States)

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

Dalton, J. B.

2005-08-01

155

Influence of hydrating agents on the hydration of industrial magnesium oxide  

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, magnesium nitrate, nitric acid, acetic acid, magnesium chloride, sodium acetate and hydrochloric acid and distilled water as control. RESULTS: There was not a significant difference in the hydration be...

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

2010-01-01

156

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

157

Mutagenesis of Bacteria by Fibrous or Clay Minerals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Naoto Yoshida; Tadahumi Naka; Kazuyoshi Ohta

2004-01-01

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

1991-12-01

159

Fast x-ray fluorescence microtomography of hydrated biological samples.  

Science.gov (United States)

Metals and metalloids play a key role in plant and other biological systems as some of them are essential to living organisms and all can be toxic at high concentrations. It is therefore important to understand how they are accumulated, complexed and transported within plants. In situ imaging of metal distribution at physiological relevant concentrations in highly hydrated biological systems is technically challenging. In the case of roots, this is mainly due to the possibility of artifacts arising during sample preparation such as cross sectioning. Synchrotron x-ray fluorescence microtomography has been used to obtain virtual cross sections of elemental distributions. However, traditionally this technique requires long data acquisition times. This has prohibited its application to highly hydrated biological samples which suffer both radiation damage and dehydration during extended analysis. However, recent advances in fast detectors coupled with powerful data acquisition approaches and suitable sample preparation methods can circumvent this problem. We demonstrate the heightened potential of this technique by imaging the distribution of nickel and zinc in hydrated plant roots. Although 3D tomography was still impeded by radiation damage, we successfully collected 2D tomograms of hydrated plant roots exposed to environmentally relevant metal concentrations for short periods of time. To our knowledge, this is the first published example of the possibilities offered by a new generation of fast fluorescence detectors to investigate metal and metalloid distribution in radiation-sensitive, biological samples. PMID:21674049

Lombi, Enzo; de Jonge, Martin D; Donner, Erica; Kopittke, Peter M; Howard, Daryl L; Kirkham, Robin; Ryan, Chris G; Paterson, David

2011-01-01

160

Minerals | Special Issue : Advances in Mineral Geochronology  

...Minerals | Special Issue : Advances in Mineral Geochronology Submit to Minerals Login Register MDPI Journals A-Z For Authors For Editors For Librarians About Open Access ... 1 (2011) Special Issue \\

 
 
 
 
161

Energy resource potential of natural gas hydrates  

Science.gov (United States)

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

Collett, T. S.

2002-01-01

162

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

Science.gov (United States)

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

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

2008-07-15

163

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

164

Epidemiological follow-up of uranium miners in Canada  

International Nuclear Information System (INIS)

The hazards of exposure of uranium miners to high concentrations of radon and radon daughters have been recognized for several decades. Quantitative estimates of risk based on epidemiological followup of exposed miners are becoming increasingly available in recent years. The present report deals with four studies of Canadian miners; the results are compared with those of two other major studies of U.S. and Czechoslovakian uranium miners

1988-01-01

165

Adsorption of dextrin on hydrophobic minerals.  

Science.gov (United States)

The adsorption of dextrin on talc, molybdenite, and graphite (three naturally hydrophobic minerals) has been compared. Adsorption isotherms and in situ tapping mode atomic force microscope (TMAFM) imaging have enabled polymer adsorbed amount and morphology of the adsorbed layer (area coverage and polymer domain size) to be determined and also the amount of hydration water in the structure of the adsorbed layer. The effect of the polymer on the mineral contact angles, measured by the captive bubble method on cleaved mineral surfaces, indicates clear correlations between the hydrophobicity reduction of the minerals, the adsorbed amount, and the surface coverage of the adsorbed polymer. Predictions of the flotation recovery of the treated mineral phases have been confirmed by performing batch flotation experiments. The influence of the polymer surface coverage on flotation recovery has highlighted the importance of this key parameter in the predictions of depressant efficiency. The roles of the initial hydrophobicity and the surface structure of the mineral basal plane in determining adsorption parameters and flotation response of the polymer-treated minerals are also discussed. PMID:19514751

Beaussart, Audrey; Mierczynska-Vasilev, Agnieszka; Beattie, David A

2009-09-01

166

Storage capacity of hydrogen in gas hydrates  

International Nuclear Information System (INIS)

The storage capacity of H2 in the THF, THT, and furan hydrates was studied by p-V-T measurements. We confirmed that the storage and release processes of H2 in all hydrates could be performed reversibly by pressure swing without destroying of hydrate cages. H2 absorption in both THT and furan hydrates is much faster than THF hydrate in spite of same unit-cell structure. On the other hand, the storage amounts of H2 are coincident in the all additive hydrates and would reach at about 1.0 mass% asymptotically.

2010-03-01

167

Lung Cancer in uranium miners  

International Nuclear Information System (INIS)

This paper analyese the clinical data of 39 uranium miners with lung cancer and of 20 patients with lung cancer who have not been exposed to uranium as control. The age of uranium miners with lung cancer was 36?61 with an average of 48.8, nine years earlier than that of the control group (57.3). In the uranium miner patients the right lung was more susceptible to cancer than the left, the ratio being 2.5:1. However, in the control group the right lung had an equal incidence of cancer as the left lung. The relative frequency of small cell anaplastic carcinoma in uranium miner was higher than that in the control group. In the miner patients the mean occupation history was 11.1 ± 5.2 years; the exposure dose to radon and its daughters in 50% patients was 0.504J(120 WLM). The etiologic factor of lung cancer in uranium miners is strongly attributed, in addition to smoking, to the exposure to radon and its daughters in uranium mines

1987-01-01

168

Hydrated gallium vanadates  

International Nuclear Information System (INIS)

By means of mixing solutions of sodium vanadate (pH 12.6; 9-8 and 5.0) and gallium nitrate (pH 2.0) the optically monophase products of the compositions: Ga_2O_3xV_2O_5x6H_2O, 2Ga_2O_3x3V_2O_5x15H_2O and Ga_2O_3x2V_2O_5x9H_2O are prepared. The latter do not contain OH-groups of the basic salts according to the data of PMR and according to cryoscopy they have molecular masses, corresponding to ortho, di- and tetravanadate of gallium of the compositions: GaVO_4x3H_2O, Ga_4(V_2O_7)_3x15H_2O and Ga_2V_4O_1_3x9H_2O. The compounds contain molecules of the adsorbed water with different adsorption centres. Part of the molecules of hydrate water stays in the Ga"3"+ cation coordination sphere. Gallium vanadates are X-ray amorphous in air-dry state. . According to the data of IR spectroscopy it is suggested that the corresponding compounds contain polyhedrons GaO_6 alongside with tetrahedral groupings VO_4. Formation of crystal structures starts at 300 deg C but proceeds intensively at t>400 deg C. . The crystalline phases formed preserve their individiality up to 500 deg C. Higher 550 deg C gallium vanadates decompose with the formation of Ga_2O_3 and V_2O_5

1981-10-01

169

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

170

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

171

Buildings exposed to fire  

International Nuclear Information System (INIS)

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

1987-03-19

172

The supergene mineral association with brandholzite from Pernek, Malé Karpaty Mountains, Slovak Republic  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Brandholzite, a hydrated hydroxide of Mg2+ and Sb5+, was found at the Krížnica deposit near Pernek (Malé Karpaty Mountains, Slovak Republic); it is the third occurrence of this mineral phase worldwide. Crystals and crusts of brandholzite occur as surface coatings on altered shales mineralized with stibnite and pyrite. Associated minerals include roméite-like phases, sulphur, aragonite, gypsum, sén...

Sejkora J; Ozdín D; ?u?a R

2010-01-01

173

Spin depolarization in muonium by hydrated electrons  

International Nuclear Information System (INIS)

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

174

Evaluation of Superpave Mixtures Containing Hydrated Lime.  

Science.gov (United States)

The use of hydrated lime in Hot-Mix Asphalt (HMA) mixtures can reduce permanent deformation, long-term aging, and moisture susceptibility of mixtures. In addition, hydrated lime increases the stiffness and fatigue resistance of mixtures. This study evalua...

A. Raghavendra L. N. Mohammad S. Cooper S. Kabir

2013-01-01

175

Hydration of Purines, Pyrimidines, Nucleosides, and Nucleotides.  

Science.gov (United States)

Hydration is a major factor determining the structure of deoxyribonucleic acid (DNA). It was therefore of interest to examine the hydration of the molecular constituents of DNA (purines, pyrimidines, nucleosides, nucleotides, and related compounds) and to...

M. Falk

1964-01-01

176

Minerals separator  

Energy Technology Data Exchange (ETDEWEB)

A minerals separator comprising a body having a surface having the form of the inside of a spiralinder, which may be tapered, arranged when rotating about its axis to have a force acting axially along it, means for rotating the body about the axis of the spiralinder to apply a centrifugal force exceeding g to said surface, means for applying perturbations to the body, means for batchwise applying a slurry and means for batchwise applying washing liquid to a spiral line on the inside of the spiralinder, and means for collecting separately fractions of different mobilities axially along the spiralinder.

Mozley, R.H.

1990-06-13

177

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

178

The nanostructure of calcium silicate hydrate  

Science.gov (United States)

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

Chen, Jeffrey J.

179

Radon risk in ore miners  

International Nuclear Information System (INIS)

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

1997-10-21

180

Evaluation of hydration indexes in kale leaves  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Calbo, Adonai G.; Ferreira, Marcos D.

2011-01-01

 
 
 
 
181

Observation of Sintering of Clathrate Hydrates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2010-01-01

182

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

183

SPERMATID MICRONUCLEUS ANALYSES OF TRICHLOROETHYLENE AND CHLORAL HYDRATE EFFECTS IN MICE  

Science.gov (United States)

Mice were exposed by inhalation to trichloroethylene (TCE), or by i.p. injection to the TCE metabolite, chloral hydrate (CH). arly spermatids were analyzed for micronucleus (MN) frequency and kinetochore status (presence or absence) using fluorochrome-labeled anti-kinetochore ant...

184

[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

2012-01-01

185

Gas Hydrate and Pore Pressure  

Science.gov (United States)

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

Tinivella, Umberta; Giustiniani, Michela

2014-05-01

186

Hydration of highly charged ions.  

Science.gov (United States)

Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of hydrates of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the hydrates appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results. PMID:22298911

Hofer, Thomas S; Weiss, Alexander K H; Randolf, Bernhard R; Rode, Bernd M

2011-08-01

187

On minimal exposed faces  

Science.gov (United States)

In this paper we consider the problem of the non-empty intersection of exposed faces in a Banach space. We find a sufficient condition to assure that the non-empty intersection of exposed faces is an exposed face. This condition involves the concept of inner point. Finally, we also prove that every minimal face of the unit ball must be an extreme point and show that this is not the case at all for minimal exposed faces since we prove that every Banach space with dimension greater than or equal to 2 can be equivalently renormed to have a non-singleton, minimal exposed face.

García-Pacheco, Francisco Javier

2011-10-01

188

78 FR 37536 - Methane Hydrate Advisory Committee  

Science.gov (United States)

...DEPARTMENT OF ENERGY Methane Hydrate Advisory Committee AGENCY...announces a meeting of the Methane Hydrate Advisory Committee. The Federal...Office of Oil and Natural Gas, 1000 Independence Avenue SW...The purpose of the Methane Hydrate Advisory Committee is to...

2013-06-21

189

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

Energy Technology Data Exchange (ETDEWEB)

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

Jones, Keith W. [Laboratory for Earth and Environmental Sciences, Environmental Sciences Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Feng, Huan [Department of Earth and Environmental Studies, Montclair State University, Upper Montclair, NJ 07043 (United States); Tomov, Stanmire [Information Technology Division, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Winters, William J. [U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA 02543 (United States); Prodanovic, Masa [Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794-3600 (United States); Mahajan, Devinder [Energy Sciences and Technology Department, Brookhaven National Laboratory, Upton, NY 11973-5000 USA, Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY 11794-2275 (United States)

2007-03-15

190

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

Science.gov (United States)

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

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

2007-01-01

191

[Signs of chronic overheating in miners of deep coal mines].  

Science.gov (United States)

Both miners exposed to high temperature and excess heat and miners working under permissible temperature conditions (a control group) had similar nonspecific signs, i. e., complaints of heartache and headache, erethism, flaccidity, hydrosis, degradation of appetite and sleep, vertigo, dimness, the sense of air shortage, palpitation in rest, uncertain gait, muscle spasm. There were also presented the following objective data: tremor of close eyelids, asymmetry of tendon reflex, convergence weakness, emotional lability, changes in orthostatic test results, higher Kerdau index, instability of sensitizing Romberg's test. The above signs were more pronounced in miners exposed to high temperature, thus it was possible to regard them as indicators of miners' chronic overheating. PMID:2767495

Peftiev, I F; Maksimovich, V A

1989-01-01

192

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

193

Phenomenological model of phase transformations of gas hydrates in porous media: Visco-plastic consolidated skeleton  

Science.gov (United States)

We develop a phenomenological model to describe the behavior of natural porous media saturated with phases that can experience phase transformations which result in changes of the strength, rheology, and transport properties of the medium. A porous medium saturated with gas hydrates cementing the grains of a mineral skeleton is an example of such behavior. On a decrease in pressure or increase in temperature, hydrates in such a medium dissociate into gas and water. The resulting fluid acts as a lubricant between the skeleton grains: the elastic response is changed by the viscous response, and the processes of consolidation and multiphase filtration in the deforming skeleton are initiated.

Izvekov, O. Ya.; Konyukhov, A. V.

2013-11-01

194

High activated mineral admixture slurry made by wet-discharged fly-ash promoted by matrix bonding component  

Energy Technology Data Exchange (ETDEWEB)

The mineral admixture slurry was made by wet-discharged fly-ash (WDFA) promoted by matrix bonding component (MBC), and the strengths, hydration products change (XRD, SEM) of cement paste made by the slurry were studied. The results indicate that in the process of wet-milling preparation, there is a prime proportion (70:30) between wet-discharged fly-ash and matrix bonding component in the slurry. The physical activation of wet-milling and chemical activation of modified agents accelerate the hydration of cement including the cement and mineral which has not hydrated completely in the matrix bonding component. The hydrated part of matrix bonding component can play the function of inducing crystallization, which can accelerate secondary hydration reaction of fly-ash.

Baoguo Ma; Zhongtao Luo; Xiangguo Li; Meixiang Zhang; Yingbin Wang [Wuhan University of Technology, Wuhan (China). Key Laboratory for Silicate Materials Science & Engineering of Ministry of Education

2009-10-15

195

Structure of the hydrated electron  

International Nuclear Information System (INIS)

An intuitive 4-water structure of the hydrated electron based on recent threshold photoionization studies is analyzed in light of past kinetic, thermodymamic, and spectroscopic measurements. It is concluded that the equilibrium state of the hydrated electron may actually be the complex (OH"-...H_3O)(aq). The central feature is an H_2O"- anion with a large distortion of one OH bond caused by the presence of the localized excess electron. A structure for the hydrated dielectron is also suggested. In these structures, thermodynamic stability is gained through hydration of the hydroxyl ion, while spectroscopic properties mainly arise from the oxonium radical. In order to examine these structures more extensively, quantum theoretical computations using Gaussian 82 have been carried out on (H_2O)/sub N/"- with N = 1 and 4. The computations do suggest a propensity to form a single stretched OH bond when a localized excess electron is present. This feature is similar to conclusions reached by Bettendorff, Buenker, and Peyerimhoff from extensive CI calculations on the isoelectronic monomeric species HF"-, where two structures participate in an in-out dual stability: (1) a delocalized electron with a localized hydrogen atom (normal H-F bond), or (2) a localized electron with a delocalized hydrogen atom (distended H-F bond). In solution, solvent interactions are expected to lower the energy of the localized electron structure compared with the delocalized one

1987-06-04

196

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

197

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

198

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

199

Effects of Sediment Type and Salinity on the Formation and Dissociation of Carbon Dioxide Hydrate  

Science.gov (United States)

The effect of sediment type and salinity on the storage of carbon dioxide in deep sea sediments has been identified in this study. Deep sea sediments are characterized by fine grained silts and clays with small mean pore diameters as well as various chemical compositions. Understanding the hydrate equilibrium data at different type of surface chemistry is important in evaluating the interaction of host sediments and injected CO2 which could influence the long-term stability of the surrounding geologic sediments after CO2 sequestration. Hydrate formation and dissociation experiments were conducted in a 50 mL pressure vessel by bubbling gaseous CO2 into liquid and suspension phases. Preliminary results involved the formation and dissociation of hydrates in colloidal suspensions containing different sediments and different salinity conditions. Over-pressurization is necessary to start the nucleation processes. Fast hydrate formation were observed in deionized water. As expected, higher over-pressurization was required and slow hydrate formation was observed in a salt (sodium chloride) solution compared to the formation in pure water alone. However, the addition of 10 g/L colloidal suspensions (bentonite, kaolinite and common terrestrial soil) reduces the pressure needed for over-pressurization. The hydrate formation kinetics in the colloidal suspensions was very similar that in pure deionized water. The hydrate dissociation experiments in the colloidal suspensions did not show any significant difference from that of pure water. Results from this research can provide insight on the formation and dissociation of carbon dioxide hydrate in the deep sea sediments and basic knowledge for the geochemical interaction at water and soil mineral interface.

Lamorena, R. B.; Jang, A.; Lee, W.

2006-12-01

200

Regulation of airway mucosal hydration.  

Science.gov (United States)

Ion channels control the hydration status of the airway epithelium through apical anion secretion and cation absorption, which is accompanied by osmotically obligated water. The key channels in this process are the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), which is principally responsible for Cl(-) secretion by airway epithelial cells, and the epithelial Na(+) channel (ENaC), which is responsible for the absorption of Na ions. In CF, defective CFTR-mediated Cl(-) secretion and an accompanying upregulation in ENaC-mediated Na absorption results in a reduction in airway surface liquid volume, leading to poorly hydrated mucus and impaired mucociliary clearance. Restoration of normal airway hydration by modulation of ion channel activity represents an important therapeutic strategy for CF. CFTR corrector and potentiator compounds are being developed with the aim of recovering normal Cl(-) secretion. Ca(2+)-activated Cl(-) channels (CaCCs) are expressed by the respiratory epithelia and are reported to be functionally upregulated in CF and offer a 'surrogate' pathway for Cl(-) secretion. TMEM16A has recently been described as a CaCC in the airway epithelium and, as such, represents an alternative target for restoring Cl(-) secretion in CF. An alternative therapeutic strategy for CF is to inhibit ENaC, thereby blocking excessive Na absorption. This can be achieved by direct blockade of ENaC or inhibition of the channel-activating proteases (CAPs), whose activity regulates ENaC function. This review will describe the regulation of airway mucosal hydration by ion channels and the efforts currently underway to restore normal mucosal hydration in disease patients by modulating the function of these channels. PMID:22111616

Paisley, Derek; Gosling, Martin; Danahay, Henry

2010-05-01

 
 
 
 
201

Seismic reflections associated with submarine gas hydrates  

Energy Technology Data Exchange (ETDEWEB)

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

Andreassen, K.

1995-12-31

202

Interstellar dust spectra between 2.5 and 3.3 microns - a search for hydrated silicates  

International Nuclear Information System (INIS)

Spectra in the 2.5-3.3 micron wavelength region of VI Cyg 12, AFGL 2205, and AFGL 2885 were obtained in a search for bound water, hydroxyl groups, and hydrated minerals in interstellar dust. No new absorption bands were found. Comparison of expected strengths of bands of serpentine and chlorite-like minerals with the data suggests that less than 25 percent and 50 percent, respectively, of the silicate in the grains is composed of these materials. 22 references

1985-01-01

203

Interstellar dust spectra between 2.5 and 3.3 ?m: A search for hydrated silicates  

International Nuclear Information System (INIS)

Spectra in the 2.5--3.3 ?m wavelength region of VI Cyg 12, AFGL 2205, and AFGL 2885 were obtained in a search for bound water, hydroxyl groups, and hydrated minerals in interstellar dust. No new absorption bands were found. Comparison of expected strengths of bands of serpentine and chlorite-like minerals with the data suggests that less than 25% and 50%, respectively, of the silicate in the grains is composed of these materials

1985-01-01

204

Stratigraphic mapping of hydrated phases in Western Ius Chasma, Mars  

Science.gov (United States)

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

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

2013-12-01

205

Natural gas hydrates: energy for the future  

International Nuclear Information System (INIS)

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

1998-10-01

206

Cohort study of mortality of vermiculite miners exposed to tremolite.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1986-01-01

207

Pockmark formation and evolution in deep water Nigeria: Rapid hydrate growth versus slow hydrate dissolution  

Science.gov (United States)

previous works, it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deep water Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics. New results obtained by drilling into gas hydrate-bearing sediments with the MeBo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid hydrate growth opposed to slow hydrate dissolution. On one hand, positive temperature anomalies, free gas trapped in shallow microfractures near the seafloor and coexistence of free gas and gas hydrate indicate rapid hydrate growth. On the other hand, slow hydrate dissolution is evident by low methane concentrations and almost constant sulfate values 2 m above the Gas Hydrate Occurrence Zone.

Sultan, N.; Bohrmann, G.; Ruffine, L.; Pape, T.; Riboulot, V.; Colliat, J.-L.; De Prunelé, A.; Dennielou, B.; Garziglia, S.; Himmler, T.; Marsset, T.; Peters, C. A.; Rabiu, A.; Wei, J.

2014-04-01

208

Thermal conductivity of hydrate-bearing sediments  

Science.gov (United States)

A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

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

2009-01-01

209

Evidence for Unconformable Deposition of Hydrated Sulfate-bearing Evaporitic Deposits in Northern Sinus Meridiani, Mars  

Science.gov (United States)

Previous analyses of OMEGA NIR spectral reflectance observations revealed mono- and poly- hydrated sulfates within layered deposits associated with a 120km long northwest-southeast trending valley located in northern Sinus Meridiani [Gendrin et al., 2005; Arvidson et al., 2005; Griffes et al., 2007]. These hydrated sulfate-bearing deposits, referred to as layered hydrated sulfate (LHS) deposits, occur in both low elevation areas on the valley floor and within higher elevation exposures near the northeastern margin of the valley that are up to 150m thick. A 200m section of sedimentary rock is exposed in a scarp wall along the southern valley margin. Hydrated sulfate spectral signatures are not detected in the scarp wall. The hydrated sulfate-bearing layers within high elevation exposures near the northeastern margin of the LHS deposits do not correspond to layers exposed in the southern scarp wall. Based on detailed stratigraphic analyses, we infer that the LHS deposits associated with the valley were unconformably deposited following the erosion of older sedimentary rocks in Sinus Meridiani. LHS deposits are spectrally and texturally distinct from the sulfate and hematite bearing unit explored by the Opportunity rover. Polyhydrated sulfates are spectrally dominant over a large area of the valley floor and monohydrated sulfates occur mainly in higher elevation portions of the LHS deposits. Analyses of high resolution CRISM, CTX, and HiRISE images reveal that layers containing monohydrated sulfates are intercalated with polyhydrated sulfate layers in these exposures. The occurrence of a thick sequence of layered deposits with hydrated sulfate spectral signatures within the valley is indicative of deposition in an evaporitic setting. Compositional layering in the LHS deposits, specifically intercalated layers of mono- and poly- hydrated sulfates, implies that multiple wetting events and/or brine recharge occurred to produce depositional layering, although diagenetic processes may have modified the initial layering. Sedimentary deposits indicative of a complex aqueous history that evolved over time are preserved in Sinus Meridiani, Mars.

Wiseman, S. M.; Arvidson, R. E.; Morris, R. V.; Poulet, F.; Bishop, J. L.; Andrews-Hanna, J. C.; Des Marais, D. J.; Griffes, J. L.; Murchie, S. L.; Seelos, F. P.

2009-12-01

210

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

Science.gov (United States)

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

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

2014-01-01

211

Mineral Sands Down Under  

Science.gov (United States)

This resource describes what mineral sands are, and discusses the heavy, dark-colored minerals that they contain (rutile, ilmenite, zircon, monazite). A map shows locations of mineral sands deposits in Australia.

212

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

International Nuclear Information System (INIS)

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

2013-06-01

213

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

Energy Technology Data Exchange (ETDEWEB)

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

Soin, Alexander V.; Catalan, Lionel J.J. [Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada); Kinrade, Stephen D., E-mail: stephen.kinrade@lakeheadu.ca [Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada)

2013-06-15

214

Gas hydrates and their reflection characteristics  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are ice-like solids composed of water molecules surrounding a gas molecule, mainly methane. The materials are considered as an important future energy source owing to their immense amounts and worldwide occurrence. The large volume of methane in hydrates would have a significant effect on the global environment change if the pressure/temperature condition changes. In the United States, Canada, Japan, Russia, and some European countries, both geophysical and geochemical studies have been conducted on the material for recognition, mapping, delineation of the origin, and assessment. Since gas hydrates are stable at relatively low temperature and high pressure conditions, they occur in two distinct locations: in polar regions associated with permafrost and in marine sediments where water depths exceed about 300 m. The stiffness in hydrate-bearing layers is dramatically increased due to intergranular cementation of gas hydrates. Accordingly, the gas-hydrate layers show seismic characteristics such as velocity reduction at their lower boundaries, polarity reversal, large amplitude, amplitude blanking, bottom-simulating reflection, and `VAMP` structures. Owing to such distinct seismic characteristics, multichannel reflection methods have been utilized to identify and locate gas hydrates in sedimentary layers. Seismic sections, obtained using the 96-channel system on R/V Onnuri as part of the 1993 Korean Antarctic Research Program, show characters which coincide with those of gas-hydrate layers. A research project on gas hydrate commenced in 1996 will reveal detailed seismic characters of the hydrate-bearing layers in the region. (author). 25 refs., 5 figs.

Kim, Ki Young [Kangwon National University, Chuncheon (Korea, Republic of); Nam, Sang Heon; Park, Byong Kwon [Korea Ocean Research and Development Institute, Ansan (Korea, Republic of)

1996-12-31

215

Gas hydrate resources of northern Alaska  

Science.gov (United States)

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

Collett, T. S.

1997-01-01

216

Ice formation during gas hydrate decomposition  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

217

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

218

DISTINCTIVE FINE-SCALE MORPHOLOGY OF HYDRATE RIDGE  

Science.gov (United States)

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

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

2009-12-01

219

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

220

Early hydration of cementitious systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Juilland, Patrick

2009-01-01

 
 
 
 
221

Gas hydrate cool storage system  

Energy Technology Data Exchange (ETDEWEB)

This invention is a process for formation of a gas hydrate to be used as a cool storage medium using a refrigerant in water. Mixing of the immiscible refrigerant and water is effected by addition of a surfactant and agitation. The difficult problem of subcooling during the process is overcome by using the surfactant and agitation and performance of the process significantly improves and approaches ideal.

Ternes, Mark P. (Knoxville, TN); Kedl, Robert J. (Oak Ridge, TN)

1985-01-01

222

Mineral geothermometers  

Energy Technology Data Exchange (ETDEWEB)

Mineral geothermometers were studied to estimate the thermal history in sedimentary basins and successfully applied to the Korean onshore and offshore basins. The opal silica-to-quartz transformation was investigated in the Pohang basin as a geothermometer. In Korean basins, the smectite-to-illite changes indicate that smectite and illite can act as the geothermometer to estimate the thermal history of the basins. The albitization reaction was also considered as a temperature indicator. Using oxygen stable isotope to study geothermal history in sedimentary basin is useful and preferred by all over the world. In these test analyses, three samples from marine basins indicated final temperature from 55 to 83 deg.C and one marine sample indicated the initial temperature of 36 deg.C. One sample from continental basin represented the final temperature from 53 deg.C and 80 deg.C. These temperatures will be corrected because these values are based on assumed value of formation water. With the samples of sidewall core and conventional core from two wells penetrated in the offshore Korea, the analysis using polarizing microscope, scanning electron microscope with EDX and cathodoluminoscope were performed for the study of sandstone diagenesis. The diagenetic stage of the sandstones developed in the B well below the depth of 1,700 m is determined as the early stage of the diagenetic window, whereas the stage in the upper part as early diagenetic stage. The stage of the analyzed sandstones from the C well is also determined as the early stage of the diagenetic window. (author). tabs., figs.

Jeong, Tae-Jin; Kwak, Young-Hoon; Huh, Dae-Gee [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

1999-12-01

223

Gas hydrates: Technology status report  

Energy Technology Data Exchange (ETDEWEB)

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

1987-01-01

224

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

225

Fundamentals and applications of gas hydrates.  

Science.gov (United States)

Fundamental understanding of gas hydrate formation and decomposition processes is critical in many energy and environmental areas and has special importance in flow assurance for the oil and gas industry. These areas represent the core of gas hydrate applications, which, albeit widely studied, are still developing as growing fields of research. Discovering the molecular pathways and chemical and physical concepts underlying gas hydrate formation potentially can lead us beyond flowline blockage prevention strategies toward advancing new technological solutions for fuel storage and transportation, safely producing a new energy resource from natural deposits of gas hydrates in oceanic and arctic sediments, and potentially facilitating effective desalination of seawater. The state of the art in gas hydrate research is leading us to new understanding of formation and dissociation phenomena that focuses on measurement and modeling of time-dependent properties of gas hydrates on the basis of their well-established thermodynamic properties. PMID:22432618

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

2011-01-01

226

Hydrate inhibitors : alternatives to straight methanol injection  

Energy Technology Data Exchange (ETDEWEB)

Hydrate formation in oil and gas pipelines can have an impact on safety and production. Methanol injection is the preferred method of inhibiting hydrate formation in pipelines. However, methanol injection can cause salt and scale precipitation, and presents an increased corrosion risk due to the presence of dissolved oxygen. Low dose hydrate inhibitors (LDHIs) can be added to the methanol or applied alone to reduce many of the drawbacks associated with straight methanol injection. This paper discussed the use thermodynamic, kinetic, and anti-agglomerant hydrate inhibitors. Case histories were used to demonstrate their application. The study showed that with proper implementation, significant reductions to methanol volumes can be obtained by using the correct hydrate inhibition program. In some cases, the use of neat methanol was replaced by low injection rates of a neat hydrate inhibitor. 17 refs., 6 tabs., 6 figs.

Hagen, S. [Baker Hughes Canada, Calgary, AB (Canada)

2010-07-01

227

Development of Alaskan gas hydrate resources  

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-06-01

228

Effects of Hydration on Mechanical Properties of a Highly Sclerotized Tissue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The jaws of the bloodworm Glycera dibranchiata consist principally of protein and melanin scaffolds with small amounts of unmineralized copper (Cu) and mineralized atacamite (Cu2Cl(OH)3) fibers in distinct regions. Remarkably, when tested in air, the regions containing unmineralized Cu are the hardest, stiffest, and most abrasion resistant. To establish the functions of jaw constituents in physiologically relevant environments, this study examines the effects of hydration on their response to...

Moses, Dana N.; Pontin, Michael G.; Waite, J. Herbert; Zok, Frank W.

2008-01-01

229

Rock magnetism of gas hydrate-bearing rocks in the Nankai Trough, offshore SW Japan  

Science.gov (United States)

For the last decade, focus on gas hydrates has been increasing because of their potential value as an energy resource and their possible impact on climate change. Convergent margins, such as the Cascadia Margin (offshore Oregon, USA) and the Nankai Trough (offshore SW Japan) are favorable locations for the formation of gas hydrates. High amplitude bottom simulating reflectors (BSR) are often considered to be indicators of the presence of gas hydrates. Rock magnetism has also appeared to be a suitable approach. Here we focus on gas hydrate-bearing rocks from hole C0008C drilled in 2008 during the IODP Expedition 316, part of the Nankai Trough Seismogenic Experiment Zone (NanTroSEIZE) drilling project. Site C0008 is located at the slope basin seaward of the splay fault. In hole C0008C, seven gas hydrates occurrences were identified by local Cl minima from ~70 to ~170 m CSF (core depth below seafloor). We conducted a high-resolution rock magnetic study from ~70 to ~110 m CSF in order to determine the nature, size and concentration of the magnetic minerals present in the cores. As a preliminary study, about 200 discrete samples were analyzed. In addition, comparison with geochemical data and scanning electron microscope observations were made.

Kars, M. A.; Kodama, K.

2013-12-01

230

Economic and exploratory review of gas hydrates and other gas manifestations of the Uruguayan continental shelf  

Energy Technology Data Exchange (ETDEWEB)

This paper discussed seismic surveys conducted to assess gas hydrate resources on the Uruguayan continental shelf in the Pelotas, Punta del Este, and the Oriental del Plata basins. The hydrates were discovered after the analysis of 1400 km of reflection seismic lines determined the presence of bottom simulating reflectors (BSRs). The surveys identified positive gas hydrate intensity reflections to identify the gas-bearing zones. The seismic anomaly formed an area of 5000 km{sup 2} with water depths of 350 to 2200 meters. The surveys also indicated the presence of thermogenic gas migration pathways that appeared in the same seismic sections as gas chimneys. Seepages at bathymetries corresponded with seepages identified in the Brazilian side of the Pelotas basin. Estimates of methane reserves contained within lattices of the frozen water molecules were presented. The gas potential of the mineralized layer was estimated at 87 TCF. The surveys verified the existence of free gas beneath a gas hydrates layer. It was concluded that Uruguay has significant gas hydrate resources, as well as additional thermogenic gas resources located within stratigraphic traps. 18 refs., 5 figs.

Santa Ana de, H.; Veroslavsky, G. [Univ. de la Republica, Montevideo (Uruguay). Facultad de Ciencias; Latronica, L.; Tomasini, J.; Morales, E.; Ferro, S.; Gristo, P.; Machado, L. [ANCAP, Montevideo (Uruguay); Ucha, N. [PetroUruguay, Buenos Aires (Argentina)

2008-07-01

231

The relation between hydration and mechanical behavior of bovine cornea in tension.  

Science.gov (United States)

The cornea is a transparent soft tissue covering the front of the eye. The biomechanical properties of the cornea have been commonly investigated by uniaxial tensile and inflation testing methods. The cornea like many other hydrated tissue swells when immersed in an ionic solution. Previous studies on hydrated tissues have shown that mechanical properties and hydration are closely related. The present study was designed to investigate the effects of thickness (hydration) variation due to swelling/dehydration on non-linear stress-strain response of the bovine cornea. Corneal strips were first air-dried and then soaked in a bathing solution until they reached an average thickness ranging from 0.3mm to 1.1mm. Based on their thickness, the samples were divided into different groups and uniaxial tests were performed to measure tensile properties. All experiments were done in mineral oil to prevent any hydration gain or loss during the tests. It was observed that swollen corneas had softer tensile properties in comparison with dehydrated ones. In particular, there was a significant difference between elastic tangent modulus of different groups (Pmechanical properties obtained from uniaxial tensile experiments are strongly dependent on thickness (water amount) of samples; therefore, careful attention must be taken in interpreting previous studies which did not fully control the thickness of specimens. PMID:24814185

Hatami-Marbini, Hamed; Rahimi, Abdolrasol

2014-08-01

232

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

233

Protein crowding affects hydration structure and dynamics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of protein crowding on the structure and dynamics of water was examined from explicit solvent molecular dynamics simulations of a series of protein G and protein G/villin systems at different protein concentrations. Hydration structure was analyzed in terms of radial distribution functions, three-dimensional hydration sites, and preservation of tetrahedral coordination. Analysis of hydration dynamics focused on self-diffusion rates and dielectric constants as a function of crowding...

Harada, Ryuhei; Sugita, Yuji; Feig, Michael

2012-01-01

234

An extended dynamical hydration shell around proteins  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The focus in protein folding has been very much on the protein backbone and sidechains. However, hydration waters make comparable contributions to the structure and energy of proteins. The coupling between fast hydration dynamics and protein dynamics is considered to play an important role in protein folding. Fundamental questions of protein hydration include, how far out into the solvent does the influence of the biomolecule reach, how is the water affected, and how are the properties of the...

Ebbinghaus, Simon; Kim, Seung Joong; Heyden, Matthias; Yu, Xin; Heugen, Udo; Gruebele, Martin; Leitner, David M.; Havenith, Martina

2007-01-01

235

A spectroscopic study of the mineral paceite (calcium acetate)  

Science.gov (United States)

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

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

2007-07-01

236

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

237

Microstructure of natural hydrate host sediments  

International Nuclear Information System (INIS)

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

2007-08-01

238

Observation of Sintering of Clathrate Hydrates  

Directory of Open Access Journals (Sweden)

Full Text Available Clathrate hydrates have recently received attention as novel storage and transportation materials for natural gases or hydrogen. These hydrates are treated as powders or particles, and moderate storage temperatures (around 253 K are set for economic reasons. Thus, it is necessary to consider the sintering of hydrate particles for their easy handling because the hydrates have a framework similar to that of ice, even though their sintering would require guest molecules in addition to water molecules. We observed the sintering process of clathrate hydrates to estimate the rate of sintering. Spherical tetrahydrofuran (THF hydrate particles were used in observations of sintering under a microscope equipped with a CCD camera and a time-lapse video recorder. We found that THF hydrate particles stored at temperatures below the equilibrium condition sintered like ice particles. The sintering part was confirmed to be not ice, but THF hydrate, by increasing the temperature above 273 K after each experiment. The sintering rate was lower than that of ice particles under the normal vapor condition at the same temperature. However, it became of the same order when the atmosphere of the sample was saturated with THF vapor. This indicates that the sintering rate of THF hydrate was controlled by the transportation of guest molecules through the vapor phase accompanied with water molecules.

Kazutoshi Gohara

2010-12-01

239

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

Science.gov (United States)

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

Barlag, Rebecca; Nyasulu, Frazier

2011-01-01

240

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

Science.gov (United States)

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

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

2013-12-27

 
 
 
 
241

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

International Nuclear Information System (INIS)

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

2010-07-01

242

Constraining clay hydration state and its role in active fault systems  

Science.gov (United States)

understand the role of hydrated clay minerals in active fault systems, a humidity chamber connected to an X-ray diffractometer was used to determine the adsorption of water onto and/or into the crystal structure of smectite. This new type of analysis was carried out under specific temperature and humidity conditions, using powdered clay size fractions (< 2 µm) of rock samples from the San Andreas Fault (USA) and the Nankai Trough (Japan). Pressure cannot be controlled, but does not significantly affect clay swelling at shallow conditions. Air-dried samples show a discrete smectite phase that swells after traditional ethylene glycolation to an interlayer distance of 1.5 and 1.7 nm. Using the humidity chamber, however, the samples show a shorter interlayer distance, between 1.09 and 1.54 nm. Based on our analysis, we show that (i) ethylene glycol overestimates the size of the interlayer space, and therefore water content, so is a crude maximum only; (ii) interlayer swelling occurs in smectite clay minerals at all temperatures between 25 and 95°C; and (iii) particle orientation increases with increasing humidity, indicating a higher mobility of smectite from interlayer hydration. Detailed characterization of the hydration state of smectite under original conditions is critical for understanding of clay-fluid interaction, the mechanical behavior during fault displacements, and fluid budgets at depth. We propose that humidity chamber experiments should be the new standard procedure to constrain swelling characteristics of natural and synthetic clay minerals.

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

2013-04-01

243

Scientists Explore Large Gas Hydrate Field off Oregon Coast  

Science.gov (United States)

... of frozen deposits of natural gas known as "gas hydrates." Funded largely by the National Science ... was the fast rate at which gas hydrate is forming. When hydrate forms rapidly, the salts in the ...

244

Spectrophotometric Determination of Thorium in Low Grade Minerals and Ores  

International Nuclear Information System (INIS)

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

1960-01-01

245

Quick Assessment of Potential Hydrate Promoters for Rapid Formation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2012-01-01

246

Sorption Energy Maps of Clay Mineral Surfaces  

Energy Technology Data Exchange (ETDEWEB)

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

Cygan, Randall T.; Kirkpatrick, R. James

1999-07-19

247

Sorption Energy Maps of Clay Mineral Surfaces  

International Nuclear Information System (INIS)

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

1999-01-01

248

Formation rate of natural gas hydrate  

Energy Technology Data Exchange (ETDEWEB)

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

Mork, Marit

2002-07-01

249

A realistic molecular model of cement hydrates.  

Science.gov (United States)

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. PMID:19805265

Pellenq, Roland J-M; Kushima, Akihiro; Shahsavari, Rouzbeh; Van Vliet, Krystyn J; Buehler, Markus J; Yip, Sidney; Ulm, Franz-Josef

2009-09-22

250

A realistic molecular model of cement hydrates  

Science.gov (United States)

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/cm3) 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, Roland J.-M.; Kushima, Akihiro; Shahsavari, Rouzbeh; Van Vliet, Krystyn J.; Buehler, Markus J.; Yip, Sidney; Ulm, Franz-Josef

2009-01-01

251

Hydration in soccer: a review  

Directory of Open Access Journals (Sweden)

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

Monteiro Cristiano Ralo

2003-01-01

252

Hydration in soccer: a review  

Scientific Electronic Library Online (English)

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

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

253

Hydration dynamics of aqueous nitrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aqueous nitrate, NO3–(aq), was studied by 2D-IR, UV–IR, and UV–UV time-resolved spectroscopies in combination with molecular dynamics (MD) simulations with the purpose of determining the hydration dynamics around the anion. In water, the D3h symmetry of NO3– is broken, and the degeneracy of the asymmetric-stretch modes is lifted. This provides a very sensitive probe of the ion–water interactions. The 2D-IR measurements reveal excitation exchange between the two nondegenerate asymmet...

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

2013-01-01

254

Hydration behaviour of polyhydroxylated fullerenes  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-28

255

Protein dynamics: hydration and cavities  

Directory of Open Access Journals (Sweden)

Full Text Available The temperature-pressure behavior of proteins seems to be unique among the biological macromolecules. Thermodynamic as well as kinetic data show the typical elliptical stability diagram. This may be extended by assuming that the unfolded state gives rise to volume and enthalpy-driven liquid-liquid transitions. A molecular interpretation follows from the temperature and the pressure dependence of the hydration and cavities. We suggest that positron annihilation spectroscopy can provide additional quantitative evidence for the contributions of cavities to the dynamics of proteins. Only mature amyloid fibrils that form from unfolded proteins are very resistant to pressure treatment.

Heremans K.

2005-01-01

256

High heat production granites of southwest England and their associated mineralization: a review  

International Nuclear Information System (INIS)

The structure of the exposed granites in Cornwall, Devon and the Scilly Isles and their geochemistry and mineralogy are described. The mineralization sequence, and the convective water circulation resulting from the presence of radioactive minerals are discussed. It is suggest that kaolinization and the redistribution of minerals are continuing because of the deep source of heat. (UK)

1986-02-01

257

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

258

NMR Relaxation Studies on the Hydrate Layer of Intrinsically Unstructured Proteins  

Science.gov (United States)

Intrinsically unstructured/disordered proteins (IUPs) exist in a disordered and largely solvent-exposed, still functional, structural state under physiological conditions. As their function is often directly linked with structural disorder, understanding their structure-function relationship in detail is a great challenge to structural biology. In particular, their hydration and residual structure, both closely linked with their mechanism of action, require close attention. Here we demonstrate that the hydration of IUPs can be adequately approached by a technique so far unexplored with respect to IUPs, solid-state NMR relaxation measurements. This technique provides quantitative information on various features of hydrate water bound to these proteins. By freezing nonhydrate (bulk) water out, we have been able to measure free induction decays pertaining to protons of bound water from which the amount of hydrate water, its activation energy, and correlation times could be calculated. Thus, for three IUPs, the first inhibitory domain of calpastatin, microtubule-associated protein 2c, and plant dehydrin early responsive to dehydration 10, we demonstrate that they bind a significantly larger amount of water than globular proteins, whereas their suboptimal hydration and relaxation parameters are correlated with their differing modes of function. The theoretical treatment and experimental approach presented in this article may have general utility in characterizing proteins that belong to this novel structural class.

Bokor, Monika; Csizmok, Veronika; Kovacs, Denes; Banki, Peter; Friedrich, Peter; Tompa, Peter; Tompa, Kalman

2005-01-01

259

Evaluation of hydration indexes in kale leaves  

Scientific Electronic Library Online (English)

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

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

260

Evaluation of hydration indexes in kale leaves  

Directory of Open Access Journals (Sweden)

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

Adonai G. Calbo

2011-01-01

 
 
 
 
261

Hydrate Kinetics Study and Exhibition Display Preparation  

Directory of Open Access Journals (Sweden)

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

Alexey S. Ermolaev

2011-10-01

262

Well log evaluation of natural gas hydrates.  

Science.gov (United States)

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 cont...

T. S. Collett

1992-01-01

263

Kinetics of gas hydrate nucleation and growth  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

264

Gas hydrate inhibition of drilling fluid additives  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates that form during offshore well drilling can have adverse impacts on well operational safety. The hydrates typically form in the risers and the annulus between the casing and the drillstring, and can stop the circulation of drilling fluids. In this study, experiments were conducted to measure the effect of drilling fluid additives on hydrate inhibition. Polyalcohols, well-stability control agents, lubricating agents, and polymeric materials were investigated in a stirred tank reactor at temperatures ranging from -10 degree C to 60 degrees C. Pressure, temperature, and torque were used to detect onset points of hydrate formation and dissociation. The inhibitive effect of the additives on hydrate formation was quantified. Phase boundary shifts were measured in terms of temperature difference or sub-cooling gained when chemicals were added to pure water. Results showed that the multiple hydroxyl groups in polyalcohol chemicals significantly inhibited hydrate formation. Polymeric and polyacrylamide materials had only a small impact on hydrate formation, while sulfonated methyl tannins were found to increase hydrate formation. 6 refs., 1 tab., 4 figs.

Xiaolan, L.; Baojiang, S.; Shaoran, R. [China Univ. of Petroleum, Dongying (China). Inst. of Petroleum Engineering

2008-07-01

265

HEPATOCARCINOGENICITY OF CHLORAL HYDRATE, 2-CHLOROACETALDEHYDE, AND DICHLOROACETIC ACID IN THE MALE B6C3F1 MOUSE  

Science.gov (United States)

Chloral hydrate (CH) and 2-chloroacetaldehyde (CAA) have been identified as chlorination by-products in drinking water. oth chemicals are genotoxic, but their carcinogenic potential had not been adequately tested. hese bioassays were conducted using male B6C3F1 mice exposed to 1 ...

266

Effect of Zeolite for Methane Hydrate Formation  

International Nuclear Information System (INIS)

Methane hydrate is formed by physical binding between water molecules and gases such as methane, ethane, propane, or carbon dioxide, etc., which are captured in the cavities of water molecules under the specific temperature and pressure. More than 99% of naturally produced methane hydrate consists of methane, and is widely dispersed in the continental slope and continental Shelf of the Pacific and the Atlantic, the Antarctica, etc. The reserve of fossil fuel is 500 billion carbon ton and the reserve of methane is 360 million carbon ton. The reserve of gas hydrate is more than 1 trillion carbon ton, which is twice the fossil fuel. Therefore, natural gas hydrate as a kind of gas hydrate is expected to replace fossil fuel as new energy source of 21st century. Also 1 m3 hydrate of pure methane can be decomposed to the maximum of 216 m3 methane at standard condition. If these characteristics of hydrate are reversely utilized, the natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18?25% less than that of the liquefied transportation. However, when natural gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation is focused on the rapid production of hydrates and on the increases of gas consumption by adding natural zeolite into pure water. The results of the study show that the equilibrium pressure in natural zeolite is more lower than that in distilled water, and methane hydrate could be formed rapidly during pressurization, if the subcooling is maintained at 8K or above in distilled water and 6.5K or above in natural zeolite, respectively. Also, the amount of consumed gas volume in natural zeolite is more higher than in distilled water at the same experimental conditions. Also, when the natural zeolite of 0.01 wt% was added to distilled water, the amount of consumed gas was about four times higher than that in distilled water and the hydrate formation time decreased at the low subcooling temperature. Therefore, it is found that natural zeolite acts as a catalyst in hydrate formation

2011-01-01

267

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

268

Methane hydrates in the Chilean continental margin  

Scientific Electronic Library Online (English)

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

Esteban, Morales G..

2003-08-15

269

Hydrated polyvanadatomolybdates of alkali metals  

International Nuclear Information System (INIS)

Hydrated olyvanadatomolybdates of the general formula Mesub(2)Vsub(12-x)Mosub(x)Osub(y) x nHsub(2)O, where M-Li, Na, K, 0 < x <= 303.7 < y <= 32.2, 6.0 < n <= 11.2, which present solid solutions of molybdenum substitution for vanadium in corresponding dodecavanadates, have been prepared for the first time. The compounds contain V"4"+, its atomic ratio to Mo"6"+ decreasing with x increase. The temperature of the maximum value of endoeffect of the dehydration first stage both for dodecavanadates and for polyvanadatomolybdates is the highest for Na 195-205 deg C and is somewhat lower for Li 180-190 deg C and K 175-185 deg C. Complete decomposition of hydrates dodecavanadates of Li, Na, K takes place at 325, 385 and 365 deg C respectively, and of polyvanadatomolybdates of Li, Na and K at the maximum degree of molybdenum substitution for vanadium - at 350, 400 and 410 deg C respectively. Phases of the system M_2O-MoO_3-V_2O_5-V_2O_4 are the products of thermolysis of the compounds studied

1985-06-01

270

Streaming potential measurement for hydrate dissociation monitoring  

Energy Technology Data Exchange (ETDEWEB)

The production of natural gas from marine gas hydrates presents numerous technical challenges. Hydrate production involves the phase transition of the hydrates from a solid to fluid, which can results in significant changes to the petrophysical, geophysical, and geomechanical properties of the hydrate reservoir. In this study, streaming potential measurements were used to study the dissociation behavior of gas hydrates during natural gas production from a methane hydrate-bearing formation. Streaming potential is the electric potential created by ions induced towards the surface of solid grains in porous media. The technique recorded electric potential transients order to capture the diffusion of pressure pulses within the formation. Pressure field diffusion was governed by increases in fluid flow during the hydrate dissociation process. A model was then developed to evaluate the sensitivity of the transient signals in relation to the formation's mobility contrast. A horizontal layer of hydrate-bearing formation was modelled in a formation with no permeability. A water-filled vertical well was placed through the different layers of the model's formation. The model assumed an electrically quasi-static conditions. The pressure diffusion equation was solved using the finite difference method in order to obtain time transients of local pressure gradients. The study showed that voltage signal relaxation was attributed to differences in the way pressure diffuses in the hydrate zone. Pressure relaxed rapidly in the dissociated region, while low permeability in the hydrate region impeded the diffusion of the pressure disturbance. Results of the simulations indicated that the progression of the dissociation front can be monitored by continuous streaming potential measurements. 4 refs., 1 tab., 3 figs.

Ikegami, T.; Morikami, Y.; Fujii, K.; Suzuki, K.; Imasato, Y. [Schlumberger, Kanagawa (Japan); Chen, M.Y. [Schlumberger Doll Research, Cambridge, MA (United States); Yasuda, M. [Japan Oil, Gas and Metals National Corp., Chiba (Japan)

2008-07-01

271

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

272

The application of thermal analysis to the hydration and conversión Reactions of calcium alumínate Cements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The hydration of calcium aluminates cements is dominated by that of CA, CaAl2O4, which is a major constituent of all of them. At ambient temperatures, CAH10 and an amorphous phase are formed initially, but these are metastable and slowly (or more rapidly if exposed to higher temperatures) transform into C3AH6 and gíbbsite. This conversion reaction is accompanied by and increase ...

Bushnell-watson, S. M.; Sharp, J. H.

1992-01-01

273

NMR Relaxation Studies on the Hydrate Layer of Intrinsically Unstructured Proteins  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Intrinsically unstructured/disordered proteins (IUPs) exist in a disordered and largely solvent-exposed, still functional, structural state under physiological conditions. As their function is often directly linked with structural disorder, understanding their structure-function relationship in detail is a great challenge to structural biology. In particular, their hydration and residual structure, both closely linked with their mechanism of action, require close attention. Here we demonstrat...

Bokor, Mo?nika; Csizmo?k, Veronika; Kova?cs, De?nes; Ba?nki, Pe?ter; Friedrich, Peter; Tompa, Peter; Tompa, Ka?lma?n

2005-01-01

274

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

275

Methane Recovery from Hydrate-bearing Sediments  

Energy Technology Data Exchange (ETDEWEB)

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

J. Carlos Santamarina; Costas Tsouris

2011-04-30

276

Mineral spirits poisoning  

Science.gov (United States)

... the harmful effects from swallowing or breathing in mineral spirits. This is for information only and not ... The poisonous ingredients in mineral spirits are hydrocarbons, which ... only hydrogen and carbon. Examples are benzene and methane.

277

Phase relations and crystal chemistry of secondary uranium minerals of the torbernite group  

International Nuclear Information System (INIS)

Various methods of synthesizing torbernite, autunite, saleeite, natro-autunite and hydrogen autunite and their lower hydrates have been tried and assessed. Analytical methods suited to these minerals have been set up using wet chemical analysis (titrimetry, colourimetry and atomic absorption spectrometry), electron microprobe analysis and x-ray diffractometry. (author)

1984-01-01

278

Phase relations and crystal chemistry of secondary uranium minerals of the torbernite group  

Energy Technology Data Exchange (ETDEWEB)

Various methods of synthesizing torbernite, autunite, saleeite, natro-autunite and hydrogen autunite and their lower hydrates have been tried and assessed. Analytical methods suited to these minerals have been set up using wet chemical analysis (titrimetry, colourimetry and atomic absorption spectrometry), electron microprobe analysis and x-ray diffractometry.

John, D.

1984-01-01

279

Secondary Minerals in Martian Meteorite MIL 03346 as Detected by Raman Imaging Spectroscopy  

Science.gov (United States)

We report a preliminary study of MIL 03346,168 thin section by using the Raman imaging spectroscopy. Our goal is to get the spatial relationship of secondary hydrated minerals in this meteorite and to seek evidences that may hint their origins.

Ling, Z. C.; Wang, A.

2014-06-01

280

Chelated minerals for poultry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 confu...

Sl, Vieira

2008-01-01

 
 
 
 
281

Minerals | Special Issues  

... Kaksonen) 31 August 2014 0 Advances in Biominerals (Guest Editor: David Post Allison) 31 January 2012 7 Advances in Economic Minerals (Guest Editor: Michael Meyer) 31 August 2012 11 Advances in Low-temperature Computational Mineralogy (Guest Editor: Udo Becker) 15 December 2013 1 Advances in Mineral Geochronology (Guest Editor: Antonio Simonetti) 28 February 2014 0 Advances in Mineral Processing (Guest Editors: Roger Smart, Kota Hanumantha Rao) 30 September 2012 8 CO2 Sequestration by Mineral Carbonation: Challenges and Advances (Guest Editor: ...

282

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

2013-09-01

283

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

284

Detection and Production of Methane Hydrate  

Energy Technology Data Exchange (ETDEWEB)

This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand processes that control production potential of hydrates in marine settings, Mallik was included because of the extensive data collected in a producible hydrate accumulation. To date, such a location had not been studied in the oceanic environment. The project worked closely with ongoing projects (e.g. GOM JIP and offshore India) that are actively investigating potentially economic hydrate accumulations in marine settings. The overall approach was fivefold: (1) collect key data concerning hydrocarbon fluxes which is currently missing at all locations to be included in the study, (2) use this and existing data to build numerical models that can explain gas hydrate variance at all four locations, (3) simulate how natural gas could be produced from each location with different production strategies, (4) collect new sediment property data at these locations that are required for constraining fluxes, production simulations and assessing sediment stability, and (5) develop a method for remotely quantifying heterogeneities in gas hydrate and free gas distributions. While we generally restricted our efforts to the locations where key parameters can be measured or constrained, our ultimate aim was to make our efforts universally applicable to any hydrate accumulation.

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

2011-12-31

285

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

Science.gov (United States)

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

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

2010-06-01

286

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

287

Electrical properties of methane hydrate + sediment mixtures  

Science.gov (United States)

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

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

2011-01-01

288

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

289

Dynamic properties of confined hydration layers.  

Science.gov (United States)

Prompted by the recent discovery that water and aqueous monovalent Na+ solutions remain fluid-like when confined to films of a few molecular layers between mica surfaces,[Raviv et al., Nature, 2001, 413, 51-54; and Raviv and Klein, Science, 2002, 297, 1540-1543] we now extend the previous study by comparing the shear- and normal-force properties of 0.1 M Na+, Cs+ and Ni2+ salt solutions which demonstrate a diverse range of behaviours under confinement. In the case of hydrated Na+ we extend the previous study to higher pressures, up to approximately 10 atmospheres, and record similar fluidity of the hydration layers at these elevated pressures. Aqueous Cs+ films under confinement between mica sheets have been found to be unable to support an applied load--that is to say they do not demonstrate any hydration repulsion regime--as a result of their lower hydration energy [see Goldberg et al., Phys. Chem. Chem. Phys., 2008, 10, 4939-4945] which contrasts with the properties of Na+. We show that 0.1 M Ni2+ solution remains close to its bulk viscosity down to nanometre thin films, but does not demonstrate a hydration repulsion. By comparing the properties of this range of cations, with differing valency and hydration, we aim to examine the conditions under which ions serve as effective lubricants and what we call the 'hydration lubrication' mechanism. PMID:19227367

Perkin, Susan; Goldberg, Ronit; Chai, Liraz; Kampf, Nir; Klein, Jacob

2009-01-01

290

Modeling Natural Gas Productivity Recovery from a Hydrate Reservoir Well  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The hydrocarbon deposits have stimulated worldwide efforts to understand gas production from hydrate dissociation in hydrate reservoirs well. This paper deals with the potential of gas hydrates as a source of energy which is widely available in permafrost and oceanic sediments. It discusses methods for gas production from natural gas hydrates.

2013-01-01

291

Methane hydrate stability and anthropogenic climate change  

Directory of Open Access Journals (Sweden)

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

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

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

D. Archer

2007-04-01

292

Methane hydrate stability and anthropogenic climate change  

Directory of Open Access Journals (Sweden)

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

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

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

D. Archer

2007-07-01

293

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

International Nuclear Information System (INIS)

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

2000-04-10

294

Clathrate hydrates in cometary nuclei and porosity  

Science.gov (United States)

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

Smoluchowski, R.

1988-01-01

295

SOME STRUCTURAL STUDIES OF CLATHRATE HYDRATES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

1987-01-01

296

Proton percolation on hydrated lysozyme powders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The framework of percolation theory is used to analyze the hydration dependence of the capacitance measured for protein samples of pH 3-10, at frequencies from 10 kHz to 4 MHz. For all samples there is a critical value of the hydration at which the capacitance sharply increases with increase in hydration level. The threshold hc = 0.15 g of water per g of protein is independent of pH below pH 9 and shows no solvent deuterium isotope effect. The fractional coverage of the surface at hc is in cl...

Careri, G.; Giansanti, A.; Rupley, John A.

1986-01-01

297

Influence of humidity and temperature on the dehydration of Mg-carbonate minerals: Implications for optimizing stability of CO2 storage in minerals  

Science.gov (United States)

Production of magnesite [MgCO3] is widely acknowledged as the primary goal of carbon mineralization because its thermodynamic stability and slow dissolution kinetics enable long-term storage of CO2. However, magnesite formation is kinetically inhibited at Earth's surface conditions, under which formation of metastable hydrated Mg-carbonate minerals is favored instead. Increasing attention is being paid to carbon mineralization strategies that generate hydrated Mg-carbonate minerals because they may be produced at low temperature and low pressure without considerable investment of energy. Highly hydrated Mg-carbonate minerals, such as lansfordite [MgCO3.5H2O] and nesquehonite [MgCO3.3H2O], are also known to decompose in the dry state to more durable and less hydrous phases, such as hydromagnesite [Mg5(CO3)4(OH)2.4H2O], which ultimately may convert to stable magnesite within 10s to 100s of years. However, relatively little is known about the conditions required to promote hydromagnesite and magnesite production via this mechanism. The hydration states of many low-temperature minerals (e.g., sulfates, zeolites and smectites) are strongly dependent on temperature and atmospheric relative humidity (RH). Thus, we have undertaken a systematic study of hydrated Mg-carbonate mineral transformations under a range of temperatures and RH appropriate for carbonate mineral production and long-term storage of these minerals in near-surface environments. Samples of synthetic lansfordite, nesquehonite, dypingite [Mg5(CO3)4(OH)2.5H2O], and hydromagnesite were stored under various conditions of RH (2% to 100%) and temperature (-25 C to 75 C) for a period of at least seven months in order to examine their stability. Our experiments demonstrate that atmospheric RH and temperature are major controls on the stability of hydrated Mg-carbonate minerals. Additionally, the decomposition of these phases is marked by slow kinetics and path dependence. Decomposition of nesquehonite and lansfordite at higher temperature and low RH can also produce poorly ordered and amorphous phases, which may complicate or frustrate monitoring and carbon accounting using crystallographic techniques such as X-ray diffraction. The most significant trends observed for all Mg-carbonate minerals studied are the enhanced stability of highly hydrated phases at low RH and the relatively rapid decomposition of higher hydrates to hydromagnesite at higher RH and temperature. Finally, relatively stable hydromagnesite is more readily produced by decomposition of lansfordite and nesquehonite than from compositionally similar dypingite at high RH. Thus, it may be energetically advantageous to trap and store CO2 within nesquehonite, which forms readily at ambient temperatures, and subsequently to optimize storage conditions to promote its decomposition to more durable hydromagnesite.

Wilson, S. A.; Power, I. M.; Morgan, B.; Madsen, I. C.

2013-12-01

298

Therapeutic mineral waters  

Directory of Open Access Journals (Sweden)

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

Munteanu Constantin

2011-05-01

299

Glass powder blended cement hydration modelling  

Science.gov (United States)

The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1.17, H/S ratio of 2.5 and N/S ratio of 0.18. In the second phase of this research, theoretical models are built using a modified version of an existing cement hydration modelling code, "CEMHYD3D", to simulate the chemical reaction of the activated glass powder hydration and glass powder in cement. The modified model, which is referred to as the "MOD-model" is further used to predict the types, compositions and quantities of reaction products. Furthermore, the glass powder hydration data, which is obtained experimentally, is incorporated into the MOD-model to determine the effect of adding glass powder to the paste on the process of cement hydration and resulting paste properties. Comparisons between theoretical and experimental results are made to evaluate the developed models. The MOD-model predictions have been validated using the experimental results, and were further used to investigate various properties of the hydrated glass powder cement paste. These properties include, for example, CH content of the paste, porosity, hydration degree of the glass powder and conventional C-S-H and GP CS-H contents. The results show that the MOD-model is capable of accurately simulating the hydration process of glass powder-blended cement paste and can be used to predict various properties of the hydrating paste.

Saeed, Huda

300

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

2008-09-01

 
 
 
 
301

Hydrate-phobic surfaces: fundamental studies in clathrate hydrate adhesion reduction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Clathrate hydrate formation and subsequent plugging of deep-sea oil and gas pipelines represent a significant bottleneck for deep-sea oil and gas operations. Current methods for hydrate mitigation are expensive and energy intensive, comprising chemical, thermal, or flow management techniques. In this paper, we present an alternate approach of using functionalized coatings to reduce hydrate adhesion to surfaces, ideally to a low enough level that hydrodynamic shear stresses can detach deposits...

2011-01-01

302

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

2007-05-01

303

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-03-01

304

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

International Nuclear Information System (INIS)

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

1994-01-01

305

Fissure minerals, literature review  

International Nuclear Information System (INIS)

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

1980-01-01

306

Establishment of new equipment for testing low dosage hydrate inhibitors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

307

Physical properties of sediment containing methane gas hydrate  

Science.gov (United States)

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

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

2005-01-01

308

A pump-probe XFEL particle injector for hydrated samples  

CERN Document Server

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

309

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

310

Proton NMR relaxation of hydrated insulin powder  

International Nuclear Information System (INIS)

Water proton nuclear magnetic relaxation measurements were obtained for hydrated insulin powder as a function of the water content. For samples containing enough water to complete the hydration shell, the data for the spin-lattice and spin-spin relaxation times are consistent with a model in which water molecules exist in two phases, one exhibiting restricted motion and identified with water of hydration and another identified as free water with motions similar to ordinary water. For samples containing only water of hydration, a model for the spin-spin relaxation time is discussed, in which the water molecules relaxation is described in terms for four relaxation times. Estimates are obtained for these relaxation times, in good agreement with the experimental data. (Author)

1985-01-01

311

Vibrational dynamics of hydration water in amylose  

International Nuclear Information System (INIS)

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.)

2002-01-01

312

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

313

ConocoPhillips Gas Hydrate Production Test  

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-06-30

314

Overview: Gas hydrate geology and geography  

Energy Technology Data Exchange (ETDEWEB)

Several geological factors which are directly responsible for the presence or absence of gas hydrates have been reviewed and are: tectonic position of the region; sedimentary environments; structural deformation; shale diapirism; hydrocarbon generation and migration; thermal regime in the hydrate formation zone (HFZ); pressure conditions; and hydrocarbon gas supply to the HFZ. Work on gas hydrate formation in the geological environment has made significant advances, but there is still much to be learned. Work is continuing in the deeper offshore areas through the Ocean Drilling Program, Government Agencies, and Industry. The pressure/temperature conditions necessary for formation has been identified for various compositions of natural gas through laboratory investigations and conditions for formation are being advanced through drilling in areas where gas hydrates exist.

Malone, R.D.

1993-06-01

315

Overview: Gas hydrate geology and geography  

Energy Technology Data Exchange (ETDEWEB)

Several geological factors which are directly responsible for the presence or absence of gas hydrates have been reviewed and are: tectonic position of the region; sedimentary environments; structural deformation; shale diapirism; hydrocarbon generation and migration; thermal regime in the hydrate formation zone (HFZ); pressure conditions; and hydrocarbon gas supply to the HFZ. Work on gas hydrate formation in the geological environment has made significant advances, but there is still much to be learned. Work is continuing in the deeper offshore areas through the Ocean Drilling Program, Government Agencies, and Industry. The pressure/temperature conditions necessary for formation has been identified for various compositions of natural gas through laboratory investigations and conditions for formation are being advanced through drilling in areas where gas hydrates exist.

Malone, R.D.

1993-01-01

316

Detection and Production of Methane Hydrate.  

Science.gov (United States)

This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets caus...

B. Dugan C. Zelt G. Dickens G. Hirasaki K. Mohanty P. Jaiswal W. Chapman

2011-01-01

317

HYDRATION AND ACETYLATION OF LIMONENE: SUPPORTED HETEROPOLYACIDS  

Directory of Open Access Journals (Sweden)

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

MARIA CECILIA AVILA

2008-03-01

318

Separation of water through gas hydrate formation  

DEFF Research Database (Denmark)

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

Boch Andersen, Torben; Thomsen, Kaj

2009-01-01

319

Simulation of charged hydrated porous materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It is the goal of this work, to understand the behaviour of charged, hydrated, multiphasic materials and to find a thermodynamically consistent model, in order to perform realistic numerical simulations.

Acartu?rk, Ayhan Yusuf

2009-01-01

320

HYDRATION AND ACETYLATION OF LIMONENE: SUPPORTED HETEROPOLYACIDS  

Scientific Electronic Library Online (English)

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

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

 
 
 
 
321

Oceanic hydrates: more questions than answers  

International Nuclear Information System (INIS)

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

2000-01-01

322

X-ray contact microscopy on hydrated human chromosomes using laser-produced plasma X-rays  

International Nuclear Information System (INIS)

X-ray contact microscopy was applied on hydrated human chromosomes using laser-produced plasma X-rays. Chromosomes from human lymphocytes (RPMI 1788) were prepared on an X-ray resist (polymethylmethacrylate; PMMA) by surface-spreading technique or syringing technique. Immediately after that, the resist was mounted in a simple moist chamber, exposed to laser-produced plasma X-rays and developed. A replica film of the developed resist was made applying plasma-polymerization replica method, and was observed in a transmission electron microscope. X-ray images of unfixed, unstained and hydrated chromosome fibers with series of beads were clearly observed. (author)

1993-02-01

323

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

324

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

325

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

326

Spectroscopic methods in gas hydrate research.  

Science.gov (United States)

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

Rauh, Florian; Mizaikoff, Boris

2012-01-01

327

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

328

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

329

Charge Asymmetries in Hydration of Polar Solutes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the solvation of polar molecules in water. The center of water's dipole moment is offset from its steric center. In common water models, the Lennard-Jones center is closer to the negatively charged oxygen than to the positively charged hydrogens. This asymmetry of water's charge sites leads to different hydration free energies of positive versus negative ions of the same size. Here, we explore these hydration effects for some hypothetical neutral solutes, and two real solutes, with m...

2008-01-01

330

Carbon dioxide hydrates crystallisation in emulsion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

331

CO2 capture by gas hydrate crystallization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

332

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. Portlandite and ettringite formation and gypsum consumption were slowed down by SE adjunction. Admixture YD induced an acceleration of ettringite formation as well as gypsum consumption whereas portiandite...

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

2004-01-01

333

Hydration of polyethylene glycol-grafted liposomes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG...

Tirosh, O.; Barenholz, Y.; Katzhendler, J.; Priev, A.

1998-01-01

334

STRENGTH AND HYDRATION PROPERTIES OF CEMENT COMBINATIONS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

335

Towards Commercial Gas Production from Hydrate Deposits  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

336

Method for preparation of cadmium chloride hydrate  

International Nuclear Information System (INIS)

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 (CdCl_2x2.5H_2O required content) and increase labour productivity

1981-01-01

337

Intermolecular Hydrogen Transfer in Isobutane Hydrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 apparent...

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

2012-01-01

338

Calorimetric study of hydrated sodium molybdenum bronze  

Energy Technology Data Exchange (ETDEWEB)

Several kinds of hydrated sodium bronze with various amount of hydrogens were synthesized and the standard enthalpies of formation were determined by solution calorimetry. These enthalpies were summarized by least square method and were compared with the enthalpies of formation of hydrogen bronzes. It was found that the enthalpy of formation of the hydrated sodium bronzes was smaller than that of the hydrogen bronze and decreased with the increase in hydrogen content.

Suzuki, Takashi; Hatta, Bungo; Chin, Kin; Eda, Kazuo; Sotani, Noriyuki

2003-11-28

339

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

340

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

 
 
 
 
341

Exploration of gas hydrates. Geophysical techniques  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-07-01

342

Mapping the hydration dynamics of ubiquitin.  

Science.gov (United States)

The nature of water's interaction with biomolecules such as proteins has been difficult to examine in detail at atomic resolution. Solution NMR spectroscopy is potentially a powerful method for characterizing both the structural and temporal aspects of protein hydration but has been plagued by artifacts. Encapsulation of the protein of interest within the aqueous core of a reverse micelle particle results in a general slowing of water dynamics, significant reduction in hydrogen exchange chemistry and elimination of contributions from bulk water thereby enabling the use of nuclear Overhauser effects to quantify interactions between the protein surface and hydration water. Here we extend this approach to allow use of dipolar interactions between hydration water and hydrogens bonded to protein carbon atoms. By manipulating the molecular reorientation time of the reverse micelle particle through use of low viscosity liquid propane, the T(1?) relaxation time constants of (1)H bonded to (13)C were sufficiently lengthened to allow high quality rotating frame nuclear Overhauser effects to be obtained. These data supplement previous results obtained from dipolar interactions between the protein and hydrogens bonded to nitrogen and in aggregate cover the majority of the molecular surface of the protein. A wide range of hydration dynamics is observed. Clustering of hydration dynamics on the molecular surface is also seen. Regions of long-lived hydration water correspond with regions of the protein that participate in molecular recognition of binding partners suggesting that the contribution of the solvent entropy to the entropy of binding has been maximized through evolution. PMID:21761828

Nucci, Nathaniel V; Pometun, Maxim S; Wand, A Joshua

2011-08-17

343

Electrical properties of polycrystalline methane hydrate  

Science.gov (United States)

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

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

2011-01-01

344

Clathrate hydrates in the solar system  

Science.gov (United States)

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

Miller, S. L.

1985-01-01

345

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)

2005-06-12

346

Radioactive minerals in Slovakia  

International Nuclear Information System (INIS)

In this paper, there is given the review of the radioactive minerals which contain uranium and thorium and their occurrence in the Slovakia. Chemical composition of most often occurred uranium minerals of West Carpaty was confirmed with wave-dispersion, occasionally energy-dispersion-roentgen microanalysis. Their identification was confirmed by roentgen diffraction or electron diffraction. Homogeneity, occasionally heterogeneity of studied samples was verified by scanning line electron microscope. The development of the uranium mineralization is given, too

1997-10-21

347

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

International Nuclear Information System (INIS)

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

2002-06-01

348

Hydrate pingoes at Nyegga: some characteristic features  

Science.gov (United States)

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

Hovland, M.

2009-04-01

349

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Houston Jacqueline R; Maxwell Robert S; Carroll Susan A

2009-01-01

350

Mineral Classification Exercise  

Science.gov (United States)

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

Perkins, Dexter

351

Mineral Industry Surveys  

Science.gov (United States)

The US Geological Surveys Mineral Industry Survey's Web site provides "periodic on-line statistical and economic publications designed to provide timely statistical data on production, distribution, stocks, and consumption of significant mineral commodities." Visitors to the site will find an alphabetical listing of minerals that includes everything from Aluminum, Antimony, Arsenic, and Asbestos, to Zeolite, Zinc, and Zirconium. Once clicked, a brief description of the mineral is provided along with links to yearly information publications as well as special publications such as its historical statistics, other agency links, contact information, and more.

352

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

353

Controls on carbon mineralization in ultramafic mine tailings  

Science.gov (United States)

Carbon mineralization in ultramafic mine tailings provides the opportunity to offset a significant portion of CO2 emissions from mining operations if passive mineralization rates are accelerated. To help design acceleration strategies, it is important to determine the controls on carbon mineralization in tailings, and to capture these effects using a reactive transport model to provide better estimation of the rates that could be achieved at different mine sites. For instance, it is likely that climatic variables influence rates of passive carbon mineralization. We use the reactive transport model MIN3P [1] to investigate the degree to which temperature, rainfall, and evaporation control passive carbon mineralization rates, as constrained with field observations from a mine site. Preliminary results suggest that hot and dry climates are most suitable. In addition, experimental evidence suggests that passive carbon mineralization is largely limited by the rate of CO2 supply into pore waters [2]. Acceleration could be achieved in part by supplying CO2-rich gas streams into tailings to carbonate highly reactive low abundance (content along the flow path and brucite grain size on carbon mineralization efficiency was investigated. Because water acts as both a reaction medium for CO2 and brucite dissolution and as a reactant to form hydrated carbonate minerals that sequester CO2, the extent of carbon mineralization was found to mimic the water content distribution. At low water content (content from the pore to the field scale therefore complicate the assessment of the carbon mineralization potential of a mine site. Thus, the experimental data were used to calibrate MIN3P [4] to better account for the control of water content on mineral reactivity and allow more robust estimation of CO2 sequestration potential. The brucite grain size also influenced the rate and extent of carbon mineralization due to its effect on reactive surface area and the degree of surface passivation. An empirical function was derived and implemented in MIN3P to model the declining reactivity of brucite with reaction progress due to passivation of the mineral surface via carbonate precipitation. This experimentally calibrated reactive transport code, and the constraints provided by field observations, will enable better assessment of the CO2 sequestration capacity of mine sites and help guide implementation of acceleration strategies. For example, a target water content for a tailings storage facility to maximize carbon mineralization could be estimated. [1] Bea et al. (2012) Vadose Zone J 11. [2] Wilson et al. (2010) Environ Sci Technol 44, 9522-9529. [3] Harrison et al. (2013) Environ Sci Technol 47, 126-134. [4] Molins and Mayer (2007) Water Resour Res 43, W05435.

Harrison, A. L.; Power, I. M.; Dipple, G. M.; Mayer, K. U.; Wilson, S. A.

2013-12-01

354

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

355

Thermodynamic modeling for clathrate hydrates of ozone  

International Nuclear Information System (INIS)

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

2013-09-01

356

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

357

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

Energy Technology Data Exchange (ETDEWEB)

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

Mahoney, J.

2001-12-01

358

Uranium mineralization in Slovakia  

International Nuclear Information System (INIS)

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

1997-01-01

359

UK activists expose Canada'  

...UK activists expose Canada's tarred reputation Climate & Capitalism An ecosocialist journal Home About Ecosocialist Notebook Book Reviews Archives Articles By Subject Articles by Date MRonline Monthly Review MR Press MRzine Economist’s Travelogue You are here: Home / 2012 / October / 18 / ...and a few heckles, I did my best to explain: “These foreign radicals from the Canadian Government are now here in Europe, trying to hijack our regulatory systems in order to pursue their radical ideological agenda of expanding the tar sands…” This was a reference to a notorious ...new resource for pipeline activists (posted on August 20, 2013) Category: Canada & Quebec, Ecosocialist Notebook | Tagged: Danny Chivers, Ian Angus Previous: Editors resign from leading environment journal Next: Nature’s matrix: Linking agriculture, conservation and food sovereignty More Ecosocialist Notebook … Pete Seeger, 1919-2014 Doug Taylor, ...

360

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-12-15

 
 
 
 
361

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

International Nuclear Information System (INIS)

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

2013-12-01

362

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

363

Gas hydrates: past and future geohazard?  

Science.gov (United States)

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

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

2010-05-28

364

Mineral Image Index  

Science.gov (United States)

This image gallery provides pictures of thousands of mineral specimens, arranged alphabetically. For each specimen, a thumbnail and a larger image are provided. Other information includes a brief description of the specimen being shown, scale bar (when available), locality data, and a link to additional information on the mineral.

365

Rocks & Mineral Solitaire  

Science.gov (United States)

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

Catania, Andrea J.; Education, San D.

366

Lithium mineral waters  

Directory of Open Access Journals (Sweden)

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

Munteanu Constantin

2011-02-01

367

Surface miner MTS 1250  

Energy Technology Data Exchange (ETDEWEB)

The German manufacturer MAN TAKRAF Foerdertechnik GmbH has developed a new series of surface miners with capacities ranging between 500-2000 bm{sup 3}/h. The Surface Miner MTS 1250, launched at MINETIME '99, is described in this article. 1 tab., 1 photo.

Hoffmann, D. [MAN TAKRAF Foerdertechnik GmbH, Leipzig (Germany). Mining and Machinery Planning dept.

1999-10-01

368

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

369

Novel Hydrogen Hydrate Structures under Pressure  

Science.gov (United States)

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

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

2014-01-01

370

Methane hydrates in quaternary climate change  

International Nuclear Information System (INIS)

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

2005-06-12

371

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

372

Hydration shells exchange charge with their protein  

International Nuclear Information System (INIS)

Investigation of the interaction between a protein and its hydration shells is an experimental and theoretical challenge. Here, we used ultrasonic pressure waves in aqueous solutions of a protein to explore the conformational states of the protein and its interaction with its hydration shells. In our experiments, the amplitude of an ultrasonic pressure wave is gradually increased (0-20 atm) while we simultaneously measure the Raman spectra from the hydrated protein (?-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity of the fluorescence background of the Raman spectrum with a typical relaxation time of 30-45 min. Second, we detect changes in the vibrational Raman spectra. To clarify these results we conducted similar experiments with aqueous solutions of amino acids and ethanol. These experiments led us to conclude that, without the presence of an ultrasonic pressure, a protein and its hydration shells are in thermodynamic and charge equilibrium, i.e. a protein and its hydration shells exchange charges. The ultrasonic wave disrupts these equilibria which are regained within 30-45 min after the ultrasonic pressure is shut off.

2010-09-15

373

Novel Hydrogen Hydrate Structures under Pressure.  

Science.gov (United States)

Gas hydrates are systems of prime importance. In particular, hydrogen hydrates are potential materials of icy satellites and comets, and may be used for hydrogen storage. We explore the H2O-H2 system at pressures in the range 0-100?GPa with ab initio variable-composition evolutionary simulations. According to our calculation and previous experiments, the H2O-H2 system undergoes a series of transformations with pressure, and adopts the known open-network clathrate structures (sII, C0), dense "filled ice" structures (C1, C2) and two novel hydrate phases. One of these is based on the hexagonal ice framework and has the same H2O:H2 ratio (2:1) as the C0 phase at low pressures and similar enthalpy (we name this phase Ih-C0). The other newly predicted hydrate phase has a 1:2 H2O:H2 ratio and structure based on cubic ice. This phase (which we name C3) is predicted to be thermodynamically stable above 38?GPa when including van der Waals interactions and zero-point vibrational energy, and explains previously mysterious experimental X-ray diffraction and Raman measurements. This is the hydrogen-richest hydrate and this phase has a remarkable gravimetric density (18?wt.%) of easily extractable hydrogen. PMID:25001502

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

2014-01-01

374

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

375

Mineral industry in Australia  

International Nuclear Information System (INIS)

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

1982-01-01

376

Taxation of unmined minerals  

International Nuclear Information System (INIS)

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

1989-01-01

377

Disodium zinc bis­(sulfate) tetra­hydrate (zinc astrakanite) revisited  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a new low-temperature refinement of disodium zinc bis­(sulfate) tetra­hydrate {systematic name: poly[tetra-?-aqua-di-?-sulfato-zinc(II)disodium(I)]}, [Na2Zn(SO4)2(H2O)4]n or Zn astrakanite, which is an upgrade of previously reported data [Bukin & Nozik (1974 ?). Zh. Strukt. Khim. 15, 712–716]. The compound is part of an isostructural family containing the Mg (the original astrakanite mineral), Co and Ni species. The very regular ZnO(aqua)4O(sulfate)2 octa...

Di?az Vivar, M. Enriqueta; Baggio, Sergio; Iba?n?ez, Andre?s; Baggio, Ricardo

2008-01-01

378

Hydration Study Of Rice Straw Ash Admixtured Cement Using Ftir And Sem  

Directory of Open Access Journals (Sweden)

Full Text Available Rice straw ash is used as a mineral admixture to cement in the present study. Rice straw is collected from local paddy field and burnt in a clay pit . The ash was collected and grounded to a fine powder. The grounded ash was sieved using a 75 µm test sieve and replaced partially with cement at 5%, 10%, 15% and 20% by weight. The admixtured samples were hydrated for 1hour to 4 weeks and FTIR , SEM, and compressive strength analysis were carried out. The results were analyzed in the light of available literature.

S. Barathan

2013-11-01

379

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

International Nuclear Information System (INIS)

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

2008-10-01

380

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