Trapping of gas

A foam is a colloidal dispersion of gas bubbles trapped in a liquid. To produce a stable foam, several characteristics of the liquid are necessary. For example, a viscous liquid facilitates the trapping of gas bubbles. The presence of a surface active agent or stabilizer that, for structural reasons, preferentially locates on the surface of the gas bubble also provides a more permanent foam. A low vapor pressure for the liquid reduces the likelihood that the liquid molecules (particularly those surrounding the bubble) will easily evaporate, thus leading to the collapse of the foam. 

Gases that are condensable at 77K are trapped by cryocondensation . ( Cryosorption is instead the trapping of gas with a lower melting temperature inside the pores of the molecular sieve that has a huge surface/volume ratio, typically about 700m2/cm3.)... 

Another important and unique feature of plasma polymerization is the incorporation of gases that do not form polymer or solid deposits in plasma by themselves during polymer formation of organic molecules in plasma. This incorporation of gases is plasma copolymerization and not the trapping of gas molecules in plasma polymers. 

Figure 4.24 Tap to which four collection traps may be attached. Used for trapping of gas...

Splay marks Circular pattern around gate High moisture in plastic, trapping of gas in rib... 

For example, energy transfer in molecule-surface collisions is best studied in nom-eactive systems, such as the scattering and trapping of rare-gas atoms or simple molecules at metal surfaces. We follow a similar approach below, discussing the dynamics of the different elementary processes separately. The surface must also be simplified compared to technologically relevant systems. To develop a detailed understanding, we must know exactly what the surface looks like and of what it is composed. This requires the use of surface science tools (section B 1.19-26) to prepare very well-characterized, atomically clean and ordered substrates on which reactions can be studied under ultrahigh vacuum conditions. The most accurate and specific experiments also employ molecular beam teclmiques, discussed in section B2.3. 

Environmental Analysis One of the most important environmental applications of gas chromatography is for the analysis of numerous organic pollutants in air, water, and wastewater. The analysis of volatile organics in drinking water, for example, is accomplished by a purge and trap, followed by their separation on a capillary column with a nonpolar stationary phase. A flame ionization, electron capture, or... 

Although ion transmission guides and ion traps both use the same universal physical laws to achieve control over ion behavior, the ways in which the laws are used are different, as are the objectives. The guides do not retain ions to gain control over their velocities and are used simply to transmit both slow and fast ions over a very wide range of gas pressures. Ion traps retain ions over a relatively long period of time so as to adjust their kinetic energies and thereby improve mass resolution. The so-called bath gas is used at carefully controlled pressures. 

Mordenite H+ HJ(A103)3(S03)J 12-ring (free) 0.70 trapping of Kr from nuclear off-gas... 

Diffusion Pump System. After the pump line and trap have been shut off, a large valve is opened slowly enough that the mass flow of gas from the chamber through the valve into the od-diffusion pump system does not dismpt the top jet of the diffusion pump (DP) (Fig. 4). When the Hquid nitrogen is replenished after the trap has been operated for some time, release of previously trapped gas must be avoided. The so-caded ionization-gauge response pips at the start of the Hquid-nitrogen replenishment are an indication of trap ineffectiveness. 

This gas is electronegative and its molecules quickly absorb the free electrons in the arc path between the contacts to form negatively charged ions. This apparent trapping of the electrons results in a rapid build-up of dielectric strength after a current zero. The detailed. sequence of arc extinction may be summarized as follows. 

A gas trap of the type shown in Fig. 1 is suitable for this purpose. 

Pistons may be of segmented construction to permit the use of one-piece wear bands. One-piece wear bands are a requirement in API 618. Pistons have a problem in common with humans—a weight problem. Weight in a piston contributes directly to the compressor shaking forces and must be controlled. For this reason, aluminum pistons are often found in larger low pressure cylinders. Hollow pistons are used but can pose a hazard to maintenance personnel if not properly vented. If trapped, the gas will be released in an unpredictable and dangerous manner when the piston is dismantled. 

Straight-lobe compressors, or blowers, as they are commonly called are low-pressure machines. The feature unique to these compressors is that the machines do not compress the gas internally as do most of the other rotaries. The straight-lobe compressor uses two rotors that intermesh as they rotate (see Figure 1-7). The rotors are timed by a set of gears. The lobe shape is either an involute or cyclodial form. A rotor may have either two or three lobes. As the rotors turn and pass the inlet port, a volume of gas is trapped and carried between the lobes and the outer... 

Water hammer (also known as hydraulic shock) occurs in two distinct ways when the flow of liquid in a pipeline is suddenly stopped, for example, by quickly closing a valve [13], and when slugs of liquid in a gas line are set into motion by movement of gas or condensation of vapor. The latter occurs when condensate is allowed to accumulate in a steam main, because the traps are too few or out of order or in the wrong place. High-pressure mains have been ruptured, as in the following incident. 

Probably the most familiar of all clathrates are those formed by Ar, Kr and Xe with quinol, l,4-C6H4(OH)2, and with water. The former are obtained by crystallizing quinol from aqueous or other convenient solution in the presence of the noble gas at a pressure of 10-40 atm. The quinol crystallizes in the less-common -form, the lattice of which is held together by hydrogen bonds in such a way as to produce cavities in the ratio 1 cavity 3 molecules of quinol. Molecules of gas (G) are physically trapped in these cavities, there being only weak van der Waals interactions between... 

Alternative Step D Reduction with a Reductate — Sucrose (1 kg) is dissolved in water (9 liters) in a 20-liter bottle equipped with a gas trap. Baker s yeast Saccharomyces cerevisiae, 1 kg) is made into a paste with water (1 liter) and added to the sucrose solution with stirring. After lively evolution of gas begins (within 1 to 3 hours), 3-morpholino-4-(3-tert-butylamino-2-oxopropoxy)-1,2,5-thiadiazole hydrogen maleate [1.35 mols, prepared by reaction of the 3-morpholino-4-(3-tert-butylamino-2-oxopropoxy)-1,2,5-thiadiazole with an equimolar quantity of maleic acid in tetrahydrofuran]. The mixture is allowed to stand until fermentation subsides, after which the bottle is kept in a 32°C incubator until all fermentation has ended (in approximately 1 to 3 days). The yeast is filtered off with addition of diatomaceous earth and the filtrate is evaporated to dryness to give S-3-mor-pholino-4/3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazole, MP 195° to 198°C (as hydrogen maleate), according to U.S. Patent 3,619,370. 

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