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Topic: Clathrate

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	Clathrate compound - Wikipedia, the free encyclopedia
		A clathrate or clathrate compound or cage compound is a chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule.
		Clathrate complex used to refer only to the inclusion complex of hydroquinone, but recently it has been adopted for many complexes which consist of a host molecule (forming the basic frame) and a guest molecule (set in the host molecule by interaction).
		The clathrate complexes are various and include, for example, strong interaction via chemical bonds between host molecules and guest molecules, or guest molecules set in the geometrical space of host molecules by weak intermolecular force.
	en.wikipedia.org /wiki/Clathrate (432 words)

	Clathrate hydrate - Wikipedia, the free encyclopedia
		Clathrate hydrates are a class of solids in which gas molecules occupy "cages" made up of hydrogen-bonded water molecules.
		Clathrates are believed to occur in large quantities on some outer planets, moons and trans-Neptunian objects, binding gas at fairly high temperatures.
		Clathrates have also been discovered in large quantity on Earth, with hydrocarbon clathrates forming inside gas pipelines in arctic regions and giant natural methane clathrate deposits on the deep ocean floor and in permafrost regions.
	www.wikipedia.org /wiki/Clathrate_hydrate (159 words)

	Methane clathrate - Open Encyclopedia (Site not responding. Last check: 2007-10-21)
		Methane clathrates are common constituents of the shallow marine geosphere, and they occur both in deep sedimentary structures, and as outcrops on the ocean floor.
		Methane clathrates remain stable at temperatures up to 18 °C. The average methane clathrate hydrate composition is 1 mole of methane for every 5.75 moles of water, though this is dependent on how many methane molecules "fit" into the various cage structures of the water lattice.
		Sudden release of methane clathrate has been hypothesized as a cause of past climate changes, because methane is a greenhouse gas.
	open-encyclopedia.com /Methane_clathrate (287 words)

	Methane clathrate - Wikipedia, the free encyclopedia
		Methane clathrates are restricted to the shallow lithosphere (i.e.
		Methane clathrates in continental rocks are trapped in beds of sandstone or siltstone at depths of less than 800m.
		Sudden release of methane clathrate has been hypothesized as a cause of past and maybe impending climate changes, because methane is a greenhouse gas.
	www.wikipedia.org /wiki/Methane_clathrate (888 words)

	Clathrate compounds of prostaglandins or their analogues with cyclodextrin - Patent 4054736
		Prostaglandin or analogues thereof to be employed in producing cyclodextrin clathrate compounds according to this invention are those which contain the carbon skeleton of prostanoic acid or one similar to that of prostanoic acid.
		In preparing the clathrate compounds, cyclodextrin dissolved in water or in an organic solvent miscible with water is added to a prostaglandin analogue compound dissolved in an organic solvent which is miscible with water.
		The biological activities of the clathrate compounds of this invention, that is to say, hypotensive effects, contractive effects of uterine or intestinal smooth muscle, gastric secretion inhibiting effects or the like, were almost similar to those of the original prostaglandins or their analogues.
	www.freepatentsonline.com /4054736.html (4406 words)

	Methane clathrate -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-21)
		Methane clathrates are restricted to the shallow (The solid part of the earth consisting of the crust and outer mantle) lithosphere (i.e.
		Methane clathrates in continental rocks are trapped in beds of (A sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)) sandstone or silstone at depths of less than 800m.
		Sudden release of methane clathrate has been hypothesized as a cause of past and maybe impending (The weather in some location averaged over some long period of time) climate changes, because methane is a (A gas that contributes to the greenhouse effect by absorbing infrared radiation) greenhouse gas.
	www.absoluteastronomy.com /encyclopedia/m/me/methane_clathrate.htm (912 words)

	The Case For Outgassing Part Two
		A clathrate mixture of CO2 and water ice, as long as it's under a fair amount of pressure, can actually exist in a solid form even if the ground is somewhat warmer than the melting point of ordinary water ice.
		If such a buried clathrate deposit was suddenly exposed by a landslide, the result would be a blast of liquid water -- squirted outward by the pressure of the vaporizing CO2 -- which could pour down the slope for some distance before vaporizing in the thin Martian air.
		And such "briny clathrates" might exist in solid form in these cold regions, but still be warm enough to turn into a short-lived torrent of liquid brine when a landslide released the pressure on them.
	www.spacedaily.com /news/mars-water-science-00g2.html (659 words)

	Clathrate
		Inclusion adducts, also called clathrates, consist of a host molecule whose crystal structure has voids in which guest molecules may be trapped.
		Because the clathrate voids are in the shape of tunnels, the polymerization of various organic monomers included as guest with these tunnels has been possible.
		Many different monomers have been polymerized inside the tunnels of various cyclotriphosphazene clathrates and, in some cases, it was demonstrated that the macromolecules produced were stereoregular.
	research.chem.psu.edu /hragroup/clathrate.htm (326 words)

	Encyclopedia: Methane clathrate (Site not responding. Last check: 2007-10-21)
		The mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry.
		A clathrate or clathrate compound is a chemical substance consisting of a Greek klethra, meaning bars (in the sense of a lattice).
		The size of the oceanic methane clathrate reservoir is poorly known, and estimates of its size have historically decreased as knowledge of its sedimentology has increased.
	www.nationmaster.com /encyclopedia/Methane-clathrate (1745 words)

	Clathrates - little known components of the global carbon cycle
		Recently clathrates have received attention as a possible energy source, and as playing a role in large undersea slumps which could result in dangerous tsunamis, as well as in climate variability.
		Clathrates occur wherever the conditions within the sediments are in the methane-clathrate stability field, and where methane and water are available (Fig.
		This oceanic clathrate reservoir is thus enormous (at almost a third of the size of the deep ocean reservoir; Fig.
	ethomas.web.wesleyan.edu /ees123/clathrate.htm (2582 words)

	Read about Methane clathrate at WorldVillage Encyclopedia. Research Methane clathrate and learn about Methane clathrate ... (Site not responding. Last check: 2007-10-21)
		clathrate and generally found at depth in the sediment.
		The clathrates in these deep deposits are thought to have formed in-situ from the microbially-produced methane, as the δ;
		Methane clathrates in continental rocks are trapped in beds of sandstone or
	encyclopedia.worldvillage.com /s/b/Methane_clathrate (839 words)

	Method of purifying a microbicide - Patent 4973700
		A clathrate compound is a compound of the type which is formed by retaining guest molecules in the holes of host molecules.
		Clathrate compounds were produced by repeating Example 1 substantially, but employing the host compounds, the amounts of the aqueous solution of KATHON 886, the proportions of the host and guest compounds, and the reaction temperature and time which are shown in Table 1 below.
		The IR spectrum of each clathrate compound obtained in powder form was similar to that of a clathrate compound which had been produced by employing a particular solvent.
	www.freepatentsonline.com /4973700.html (2921 words)

	Antibiotic clathrates and pharmaceutical compositions thereof - Patent 4663316
		It should be noted that the clathrate complexes produced in accordance with the invention are useful not only per se, but also in combination with numerous diluents and excipients.
		The cyclodextrin clathrates produced herein are useful in a wide variety of pharmaceutical dosage forms.
		The percentage of active compound in the clathrate form was estimated to be 50%, 100% and 100% respectively in the lyophilized powder.
	www.freepatentsonline.com /4663316.html (1463 words)

	Clathrate Research Page
		However, in contrast to the diamond structure, the clathrates contain pentagonal rings and their lattices are open frameworks containing large (20-, 24-, and 28-atom) "cages".
		The implementation we use is particularly efficient for the large clathrate unit cells.
		The results for the Sn clathrates are qualitatively similar to those for all clathrates.
	www.phys.ttu.edu /~cmyles/clath.html (457 words)

	Water cluster architecture based on clathrate hydrates
		Although both non-crystalline ES clusters and crystalline gas-containing clathrates both have similar inner-shell water clustering, the topology of the outer clustering is very different.
		The lack of evidence for the partial formation of crystalline clathrates in liquid water containing clathrate-forming solutes cannot, therefore, be used to indicate the lack of formation of other clathrate structuring as suggested by some authors.
		The use of such clathrate cages in the formation of solid gas hydrate ices is shown on another page.
	www.lsbu.ac.uk /water/clathrate.html (339 words)

	THERMAL ENERGY STORAGE INC - THES Annual Report (10-K) Item 1. Business (Site not responding. Last check: 2007-10-21)
		The clathrates used by the company are formed of water mixed with certain materials having a small molecular structure which, when combined, promotes crystallization at higher freezing temperature than water alone.
		The clathrate crystals and water produce a slurry that is stored in a tank and pumped through a heat exchanger to absorb heat when the air conditioning load increases above the nominal capacity of the air conditioner.
		In this process, the clathrate former R141b is mixed with cold seawater from a depth of approximately 2,000 feet, forming a slurry of the clathrate-crystals.
	sec.edgar-online.com /2004/05/17/0000313277-04-000006/section2.asp (4016 words)

	phorum - Our World Forum at Asiawind - A new hydrogen storage for fuel cell: hydrogen clathrate hydrate.
		Clathrate: A clathrate is a compound that consists of two parts.
		In the case of the hydrogen clathrate hydrate, the lattice system of cells are made of water crystals.
		Although clathrate hydrate is much lighter than hydrides, it also has advantages over other hydrogen storage systems such as gaseous hydrogen tanks which require extremely high pressure or liquid hydrogen which require extremely low temperature.
	www.asiawind.com /forums/read.php?f=3&i=149166&t=149166 (1072 words)

	National Synchrotron Light Source
		Hydrogen molecules are considered to be too small to be enclosed in one of four possible structures of clathrate hydrates, compounds in which molecules of a substance are completely enclosed within the crystal structure of water.
		This high ratio shows that, unlike most clathrate hydrates, where only one molecule of a gas can be trapped inside the clathrate cage, many hydrogen molecules are entrapped in two types of cages (a small and a large one) within each clathrate compound.
		But this clathrate could be grown epitaxially (growth upon the surface of another crystal) on substrates of other sII clathrates or by annealing (heating to remove or prevent internal stress) hydrogen in amorphous ice.
	www.nsls.bnl.gov /newsroom/science/2003/02-Mao.htm (659 words)

	Climate and Clathrate - Physics Help and Math Help - Physics Forums
		Are you saying that clathrate (methane hydrate) events (sudden exposure and melting of large clathrate deposits) rapidly and heavily increased the methane concentration in the air, thus causing the oxygen isotope ratio to alter but NOT causing a supposed rise in temperature typically inferred from the change in oxygen isotopes?
		The same author poses here (scroll down 1/3) that continental slope failures that induce massive clathrate release coincide with Heinrich events, the Bolling Allerod event (the big spike is the greenland ice cores between 15,5 and 13,5 K years) and the onset of the holocene.
		Today I'd like to leave the clathrate were it is right now, and focus a bit on isotope behavior in the precipitation cycle in relation to temperature and the problems that have been identified already in that area, especially during the "Last Glacial Maximum" in the Greenland ice cores.
	www.physicsforums.com /showthread.php?t=42383 (2599 words)

	Global warming - Wikipedia, the free encyclopedia
		These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.
		Sudden release of methane clathrate (a greenhouse gas) has been hypothesized as a cause of past global warming.
		However, warming at the end of the last ice age is thought to not be due to clathrate release [25].
	en.wikipedia.org /wiki/Global_warming (4600 words)

	Clathrate hydrates
		Clathrate ices form from water and non-stoichiometric amounts of small non-polar molecules (hence usually gaseous) under pressure and at cold temperatures.
		Their structures require a minimum amount of small molecules to fit into and stabilize the cavities without forming any covalent or hydrogen bonds to the water molecules.
		Some clathrate hydrates can form, at atmospheric pressure, at the interface between a liquid of suitable guest molecules and water (e.g.
	www.lsbu.ac.uk /water/clathrat2.html (366 words)

	Physical Chemical Stability of Warfarin Sodium
		The crystalline clathrate form is warfarin sodium-isopropyl alcohol complex, which is prepared either from warfarin or amorphous warfarin sodium to eliminate impurities in warfarin sodium.
		On storage at 68% RH, the intensity of the peaks in the X-ray powder diffraction pattern of the clathrate warfarin sodium decreased gradually and the peak resolution decreased.
		The changes reflected the conversion from an anhydrous IPA clathrate to a crystalline form containing both IPA and water prior to converting to the amorphous state and were consistent with earlier characterizations of this system.
	www.aapspharmsci.org /view.asp?art=ps030103 (3262 words)

	Fuel Cell Today - New clathrate structure shows promise for H2 storage
		This clathrate (essentially a solid form of water with hydrogen trapped inside) holds around 50g of hydrogen per litre.
		The hydrogen is released from the clathrate when it warms to 140K, with water as a by-product.
		The hydrogen is retained in the clathrate by weak bonding, which is strong enough to stabilise molecular hydrogen, but weak enough for easy release when the temperature rises.
	www.fuelcelltoday.com /FuelCellToday/IndustryInformation/IndustryInformationExternal/IndustryInformationDisplayArticle/0,1588,831,00.html (285 words)

	January GEOLOGY and GSA TODAY media highlights
		Topics include: new synthesis of the clathrate gun hypothesis, continental slope failure, and climate change; recent insights into the Three Sisters magmatic intrusion (central Oregon); and elimination of the "time-rock" dimension of the geologic time scale.
		One of the major tests of Jim Kennett's clathrate gun hypothesis is determining whether continental-slope failures and increases in atmospheric methane correlate.
		To test the clathrate gun hypothesis we have collated published dates for submarine sediment failures in the North Atlantic sector and correlated them with climatic change for the past 45 k.y.
	www.eurekalert.org /pub_releases/2004-01/gsoa-jga010604.php (2464 words)

	Mooijer
		The high regularity and compact nature of clathrate hydrates result in a relatively large storage capacity for guest molecules, depending on the clathrate hydrate structure and its occupancy.
		To justify the applicability and feasibility of clathrate hydrate technologies knowledge on fundamentals of phase behaviour and structure is essential.
		The clathrate hydrate phase behaviour, with its relation to structure, is described with the van der Waals - Platteeuw model.
	www.dct.tudelft.nl /pcmt/html/mooijer.html (1478 words)

	CISG Canada
		Clathrate and its related compounds are also used in one form of rat poison.
		Clathrate itself consists of two key chemicals, 4-hydroxycoumarin and benzalacetone (or benzylidene acetone).
		Invamed did not pursue Diosynth as a source for clathrate because of "the ownership between Rosemont and Akzo [-Nobel]." Patel also testified that before February 1998 he did not know that Diosynth was a potential supplier.
	www.yorku.ca /osgoode/cisg/cases/geneva.htm (15048 words)

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