Occluded components

The pair of Eqs. 12, 13 epitomizes the relation between the equilibrium vapor pressure, composition, and chemical potential of the solvent in a clathrate obeying the present model. These expressions were used in the calculation of the thermodynamic properties of gas hydrates30 and have also been formulated by Barrer and Stuart 4 for a clathrate with a single type of cavity and one occluded component they reduce to the equations of ref. 52. 

Iron is a relatively abundant element in the universe. It is found in the sun and many types of stars in considerable quantity. Its nuclei are very stable. Iron is a principal component of a meteorite class known as siderites and is a minor constituent of the other two meteorite classes. The core of the earth — 2150 miles in radius — is thought to be largely composed of iron with about 10 percent occluded hydrogen. The metal is the fourth most abundant element, by weight that makes up the crust of the earth. 

The noble gases make up about 1% of the earth s atmosphere in which their major component is At. Smaller concentrations are occluded in igneous rocks, but the atmosphere is the principal commercial source of Ne, Ar, Kr and Xe, which are obtained as by-products of the liquefaction and separation of air (p. 604). Some Ar is also obtained from synthetic ammonia plants in which it accumulates after entering as impurity in the N2 and H2 feeds. World production of... 

One component formulation consists of prepolymers that are intermediate between monomers and the final polymer product. When released from a pressurized container the foaming gas expands and the prepolymer (containing unreacted cyanate groups) reacts with the moisture (water) in air to complete the polymerization reaction and cure. Because curing depends on the presence of moisture, when foam forming reactants are applied to occluded areas, such as cavities,... 

Mixed solvents are generally unsatisfactory for use in the determination of polymer molecular weights owing to the likelihood of selective absorption of one of the solvent components by the polymer coil. The excess of polarizabilit f of the polymer particle (polymer plus occluded solvent) is not then equal to the difference between the polarizabilities of the polymer and the solvent mixture. For this reason the refractive increment dn/dc which would be required for calculation of K, or of i7, cannot be assumed to equal the observed change in refractive index of the medium as a whole when polymer is added to it, unless the refractive indexes of the solvent components happen to be the same. The size Vmay, however, be measured in a mixed solvent, since only the dissymmetry ratio is required for this purpose. 

Initial °Th and Pa are generally considered to be associated with a detrital component that becomes cemented, or occluded, within the speleothem. This component may be composed of clays, alumino-silicates or Fe-oxyhydroxides (Fig. 3) with strongly adsorbed and Pa. Th and Pa incorporated in speleothems and similar deposits may also have been transported in colloidal phases (Short et al. 1998 Dearlove et al. 1991), attached to organic molecules (Langmuir and Herman 1980 Gaffney et al. 1992) or as carbonate complexes in solution (Dervin and Faucherre 1973a, b Joao et al. 1987). 

Transport of contaminants by surface runoff is illustrated in the experimental results of Turner et al. (2004), which deal with the colloid-mediated transfer of phosphorus (P) from a calcareous agricultural land to watercourses. Colloidal molybdate-reactive phosphorus (MRP) was identified by ultrafiltration associated with particles between l am and Inm in diameter. Colloidal P compounds can constitute a substantial component of the filterable MRP in soil solution and include primary and secondary P minerals, P occluded or adsorbed on or within mineral or organic particles, and biocolloids (Kretzschmar et al. 1999). 

Gross volatility differences in the components of a submitted sample may give misleading results. Occluded solvent is often the worst... 

To maintain hemostasis, blood must be retained in the vasculature as fluid. At the same time, blood components must be able to respond rapidly with a clot when a vascular injury occurs. To repair a vascular injury, platelets in blood first adhere as aggregates to the endothelial cells at the affected site and form an initial blood clot. Platelets then stimulate and activate coagulation factors found in plasma to form a more stable fibrin clot. As the injury is resolved and healed, the clot is degraded. Thrombosis is a pathological event wherein a blood clot occludes a blood vessel, resulting in ischemic necrosis of the tissue fed by the blood vessel. Ischemic necrosis involves local anemia and oxygen deprivation. Thrombosis of a coronary artery may lead to myocardial infarction or unstable angina [20]. 

On a macroscopic basis, it is difficult to remove all excess water from the hydrate mass this causes a substantial decrease in the accuracy of hydrate composition measurements. Hydrate formations often occlude water within the solid in a metastable configuration, thereby invalidating the composition obtained upon dissociation. Mixed guest compositions of the hydrate are also confounded by the concentration of heavy components in the hydrate phase. Unless the associated gas reservoir is large, preferential hydration may result in variable gas consumption and perhaps an inhomogeneous hydrate phase as discussed in Chapter 6. 

Meza, I., et al. 1980. Occluding junctions and cytoskeletal components in a cultured transporting epithelium. J Cell Biol 87 746. 

Metal cations may be soluble, readily exchangeable, complexed with organic matter, or hydrous oxides, substituted in stoichiometric compounds, or occluded in mineral structures (see reviews by Brummer et al., 1986 Beckett, 1989 Forstner, 1991). The chemical factors that affect the retention of a specific chemical form of a trace metal (e.g. effects of pH and I on specific adsorption ) are well documented (Jones and Jarvis, 1981 Tiller, 1983 McBride, 1989 1991 Alloway, 1990 Forstner, 1991). When several components co-exist in a soil, the distribution of a trace metal among them will also depend on the type and relative quantities of the soil components how they change with pH, I, etc. and the extent of saturation of adsorption sites on soil adsorbents. 

Like any muscle, the heart requires a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. In CHD, plaques or fatty substances build up inside the walls of the arteries. The plaques also attract blood components (e.g., platelets) that stick to the artery wall lining. This process, called atherosclerosis, develops gradually, over many years. It often begins early in life, even in childhood. The fatty accumulation can break open and lead to the formation of a blood clot that seals the break. The presence of the blood clot occludes the vessel and reduces blood flow. 

Difficulties in the extraction may be chiefly attributed to the microstructure of the sample to be extracted, because the efficiency of extraction may depend on whether the polymer molecule to be extracted is extented or collapsed in the outer component phase15. In the experiment shewn in Fig. 10, an extraction of PS from the acetylated sample is attempted with cyclohexane at 50 °C, after the PVAc homopolymer is removed. However, the PS homopolymer can hardly be extracted, as shown by curve 4. Since this sample is recovered by pouring the acetylation mixture i.e., the pyridine-acetic anhydride solution) into cold water, it may have a microstructure as the PS chain is collapsed, being occluded in the continuous phase of the extended PVAc. Therefore, to inyert the microstructure of the sample it should be dissolved in tetrahydrofaran again and recovered by pouring the solution into n-hexane, whose non-solvency is much stronger for PVAc than PS (at B in Fig. 10). Extraction is then carried out with cyclohexane at 50 °C. The result is shown by curve 4h in Fig. 10. It is clear that the extended PS homopolymer can be removed further by this extraction, as expected. 

Use of a high surface area graphite with little pore structure in which the active component can be occluded. 

It is interesting to note that samples containing mixtures of disulfide, disele-nide and selenosulfide crystallise forming single crystals with solvent molecules occluded in the lattice.234 31P CP/MAS measurements (Figure 46) were carried out for a three-component system in order to establish the correlation between powdered sample and single crystal.229... 

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