Massive hydrate

This requirement for a large increase in temperature below the phase boundary may have enabled the MAT Gautamala 2 sample to survive the trip from seafloor to shipboard. However, upon recovery and heating of smaller, more dispersed in situ samples at the three-phase condition, dissociation will begin almost immediately, so that the sample may not survive nonpressurized recovery. In contrast to small hydrates, massive hydrates are aided in slow dissociation by a low surface to volume ratio, together with the protective formation of an ice layer by the dissociated water (Yakushev and Istomin, 1991 Gudmundsson and Parlaktuna, 1992). 

These products are usually made from formulations of high protein content (soya, meat particles, etc.), so the continuous phase at the die exit is proteinaceous, with inclusions of carbohydrate. These products are required to deliver a significant textural strength (bite) even when fully hydrated. Massive expansion and low bulk density is not required. Instead, a degree of fibrosity (anisotropic structure) is required to simulate meat. The early structures were extruded by processes similar to those discussed above, but with a deliberately low expansion. This was achieved by extruding with a higher moisture content and die exit temperatures below 100°C (Cheftel et al. 1992 Liu et al. 2005). 

Hydration at Ordinary Temperatures. Pordand cement is generally used at temperatures ordinarily encountered in constmction, ie, from 5 to 40°C. Temperature extremes have to be avoided. The exothermic heat of the hydration reactions can play an important part in maintaining adequate temperatures in cold environments, and must be considered in massive concrete stmctures to prevent excessive temperature rise and cracking during subsequent cooling. 

Non-conventional gas is natural gas found in unusual underground conditions, such as very impermeable reservoirs which require massive stimulation in order to be recovered, or in underground occurrences of gas hydrates, or dissolved in formation water, or coal-bed methane, or gas from in-situ gasification of coal. 

Le nouveau gaz est un gaz natural qui se trouve dans des conditions souterraines inhabituelles reservoirs particulierement impermeables qui necessitent une stimulation massive pour etre exploitees, gaz sous forme d hydrates, gaz dissous dans les eaux de la formation, methane des couches de charbon ou gaz provenant de la gazeification in situ du charbon. 

Surface-contact films and massive hydrates, which form by sorption of gas and water molecules on the surfaces of growing crystals... 

A massive release of methane could cause catastrophic global climate change. Some researchers believe that the drastic climate change that occurred during the Pleistocene era was due to methane hydrate destabilization and widespread methane release. 

ADP ribosylation results in inhibition of GTPase activity and hence maintains the a-subunit in the active form. The constant activity of the G-protein results in an increase in adenyl cyclase activity and therefore a chronic increase in the cychc AMP level. This stimulates an ion channel in the enterocyte which results in a loss of Na ions and hence water from the cells into the intestine. This leads to diarrhoea and a massive loss of fluid from the body which can be sufficiently severe to result in death. Since 2000 there have been epidemics in South America and parts of central Africa. Infection is usually caused by drinking water contaminated with faecal matter. Treatment consists of hydration with rehydration fluids (Chapter 5). 

As has been proposed by numerous studies (e.g., Rohl et al. 2000 Dickens 2003) the massive release of gas hydrates could modify climate. The best example for this hypothesis are sedimentary rocks deposited at around 55 Ma during the Paleocene-Eocene thermal maximum, where a decrease of 2-3%c in carbonate-carbon is interpreted as a consequence of an abrupt thermal release of gas-hydrate methane and its subsequent incorporation into the carbonate pool. 

Outside this, a zone of perhaps 10 to 30 m thickness, which, in reasonably well-hydrated systems, is largely occupied by relatively massive calcium hydroxide crystals, with occasional interruptions of more porous regions. 

In the cement industry, the term hydration is used to describe a range of reactions between cement and water to produce a hardened product. A cement clinker particle is a multiphase solid having massive calcium silicate grains (50-100 pm) in a matrix of interstitial aluminate and ferrite. This is described as analogous to a distorted clay sequence, which traps regions of porosity-pore size distribution from nanometer to micrometer. 

About 90% of manganese ore is used in steel smelting. Although there are more than 300 manganiferous minerals, the common ore minerals are largely mixtures of manganese oxides and hydrated oxides. The usual field terms are psilomelane for a hard massive mixture of oxide minerals, pyrolusite for a soft black earthy mixture, and wad for impure, brown earthy oxides and hydrated oxides. LIBS sorting may be effective in this case (Fig. 8.11). 

ZnO films for use as buffer layers in photovoltaic cells (see Chap. 9) have been chemically deposited from aqueous solutions of ZnS04 and ammonia [57]. The solution was heated to 65°C, and adherent, compact Zn(OH)2 + ZnO films were formed after one hour. Low-temperature annealing converted the hydroxide to oxide. The solution composition will be important in this deposition. On one hand, increased ammonia concentration will increase the pH and therefore the homogeneous Zn(OH)2 precipitation in solution. However, further increase in ammonia concentration will redissolve the hydroxide as the ammine complex. There will clearly be an optimum ammonia (and zinc) concentration where Zn(OH)2 does form, but slowly enough to prevent massive homogeneous precipitation. The use of ammonia in (hydr)oxide deposition derives, in part at least, from its gradual loss by evaporation if the system is not closed [58], Any open solution of an ammonia-complexed metal ion (which forms an insoluble hydroxide or hydrated oxide) should eventually precipitate the (hydr)oxide for this reason alone. 

Geological studies have recently proved that at least four times during the past 60,000 years there were massive releases of methane from hydrates [35]. 

Hydration of Massively substituted epoxides in acid can be expected to yield significant amounts of elimination and/or rearrangement products derivable from an intermediate c rbonium ion This expectation is amply fulfilled with 2,3- poxy-2r4J4-trim thylpentane (Eq. 610), which yields in addition to the desired 1,2-diol, an unsaturated alcohol, a ketone, and several other products.61 ... 

SCORODITE. This hydrated arsenate of feme iron and aluminum (Fe . +, Mg3+)AsOz -2H20. crystallizing in the orthorhombic system, is the iron-rich isomorphous end member of a complete series extending to the aluminum-rich mineral Mansfieidite, Crystals usually occur as drusy crusts. Alsu occurs as massive, compact, ami earthy material. Hardness of 3.5 4, with specific gravity of 3.278. Vitreous to subadamantine luster, of pale green to liver-brown color. 

More importantly, the result of Booth et al. also suggests that only massive hydrate samples can survive the trip from the bottom of the ocean to ship deck. For example, if the massive MAT Guatemala 2 sample (topmost in Figure 7.7) were recovered at constant pressure, the temperature would need to rise more than 16°C before the sample reached the three-phase line, where dissociation would begin. This result is consistent not only with laboratory determinations for dispersed hydrates (Kumar et al., 2004 Pauli et al., 2005 Wright and Dallimore, 2005) but also shows the parallel of recovered core dissociation with radial dissociation due to depressurization in pipelines, modified for sediment content (Davies and Sloan, 2006). 

Rich, localized hydrate deposits Related to mounds, vents, pockmarks CH4/H2O from kilometers below seafloor High-permeability conduits Frequently are deposited in sands Forming flow rapid convective and diffusive Form within tens of meters of mud line Represent a small amount of hydrates Not normally predicted by models Can be massive gas hydrates... 

The biologically active surface (to 10 cm depth) has a methane flux that varies between 1 and 100 mmC/m2 per day. The hydrate results from free gas and gas dissolved in water. Two types of hydrate fabric result (1) porous hydrates, from accumulation of bubbles of free gas and (2) massive hydrates, with twice the density of porous hydrates (0.9 g/L versus 0.4 g/L). In the recent Raman spectroscopy, southern Hydrate Ridge experiments by the MBARI (Hester et al., 2005), the near-surface hydrate Raman specta contained significant amounts of free gas as well as hydrates, with only a trace of hydrogen sulfide in the methane gas. 

In the formation model of the above hydrate concentrations, Torres et al. (2004) indicate that the pressure of hydrate crystallization can exceed the overburden pressure. This can occur at shallow subseafloor depth, to cause massive hydrate deposits such as those shown in Figure 7.28, if hydrates do not promptly cement the grains. This finding is similar to that observed by Sassen and coworkers in the Gulf of Mexico (Personal Communication, November 10, 2005). Torres and coworkers also suggest that methane dissolved in water alone is insufficient to cause the noted hydrate concentrations—there must be additional free gas present. 

A 60-year-old woman took dexamethasone 4 mg 8-hourly for dyspnea due to a precursor T lymphoblastic lymphoma-leukemia with bilateral pleural effusions and a large mass in the anterior mediastinum (130). She developed acute renal insufficiency and laboratory evidence of the metabolic effects of massive cytolysis. She received vigorous hydration, a diuretic, allopuri-nol, and hemodialysis. She recovered within 2 weeks and then underwent six courses of CHOP chemotherapy. The mediastinal mass regressed completely. She remained asymptomatic until she developed full-blown acute lymphoblastic leukemia, which was resistant to treatment. 

The catalytic oxidation of cyclohexane is performed in the liquid phase with air as reactant and in the presence of a catalyst. The resulting product is a mixture of alcohol and ketone (Table 1, entry 12) [19]. To limit formation of side-products (adipic, glutaric, and succinic acids) conversion is limited to 10-12 %. In a process developed by To ray a gas mixture containing HC1 and nitrosyl chloride is reacted with cyclohexane, with initiation by light, forming the oxime directly (Table 1, entry 12). The corrosiveness of the nitrosyl chloride causes massive problems, however [20]. The nitration of alkanes (Table 1, entry 13) became important in a liquid-phase reaction producing nitrocyclohexane which was further catalytically hydrated forming the oxime. 

The next table illustrates the great variation of basicity and hydration shown by phosphoric acid in nature, and also of the bases with which it may combine. Minor constituents are omitted for the sake of brevity. When the crystalline system is not stated the mineral is amorphous or massive. 

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