Rapid expansion

Concepts in stereochemistry, that is, chemistry in three-dimensional space, are in the process of rapid expansion. This section will deal with only the main principles. The compounds discussed will be those that have identical molecular formulas but differ in the arrangement of their atoms in space. Stereoisomers is the name applied to these compounds. 

The end or front of the plasma flame impinges onto a metal plate (the cone or sampler or sampling cone), which has a small hole in its center (Figure 14.2). The region on the other side of the cone from the flame is under vacuum, so the ions and neutrals passing from the atmospheric-pressure hot flame into a vacuum space are accelerated to supersonic speeds and cooled as rapid expansion occurs. A supersonic jet of gas passes toward a second metal plate (the skimmer) containing a hole smaller than the one in the sampler, where ions pass into the mass analyzer. The sampler and skimmer form an interface between the plasma flame and the mass analyzer. A light... 

The ablated vapors constitute an aerosol that can be examined using a secondary ionization source. Thus, passing the aerosol into a plasma torch provides an excellent means of ionization, and by such methods isotope patterns or ratios are readily measurable from otherwise intractable materials such as bone or ceramics. If the sample examined is dissolved as a solid solution in a matrix, the rapid expansion of the matrix, often an organic acid, covolatilizes the entrained sample. Proton transfer from the matrix occurs to give protonated molecular ions of the sample. Normally thermally unstable, polar biomolecules such as proteins give good yields of protonated ions. This is the basis of matrix-assisted laser desorption ionization (MALDI). 

Rapid expansion from supercritical solutions (RESS)... 

Plant Safety. Of the many ferroalloy products produced in electric furnaces, ferromanganese has the greatest potential for furnace emptions or the more serious furnace explosions. The severity of the explosions increases with the size of the furnace. Such incidents are infrequent, but can occur, and when they do are often disastrous. Explosions usually result in extensive damage to the furnace and surrounding area, and often severe injuries or death to personnel in the immediate area. An emption is the sudden ejection of soHds, Hquids, or gases from the furnace interior. A more violent and instantaneous ejection of material, accompanied by rapid expansion of burning gas, is considered an explosion (38). 

Japan, Canada, and the United States accounted for 70% of the 1995 estimated world production of 2000 t (Table 5). At least 100 t of selenium was also available to Western markets from the former Soviet bloc. Selenium production is expected to rise in South America, particularly Chile, as the copper industry continues rapid expansion. A considerable amount of unrefined selenium is also shipped to Chile and the Philippines for conversion to final commercial product by either hydrometaHurgical or distillation processes. 

Other. Numerous other supercritical fluid processes and techniques have been and are continuing to be developed. The novel spray appHcation UNICARB uses supercritical CO2 to replace volatile diluents in coating formulations, thereby reducing the volatile organic compound emissions by up to 80% (128). Rapid expansion of CO2 iu the spray can also improve the quaUty of coatings, thus performance benefits are obtained in a process developed for environmental advantages. 

Early bottling of flavored carbonated beverages was limited by spoilage, poor flavor, and color stabiUty. Improvements and innovations in bottling equipment, glass manufacturing, stable flavors and ingredients, crown closures, and transportation resulted in the rapid expansion of the bottled soft drink industry. Soft drinks consist of carbonated water, nutritive or nonnutritive sweeteners, acidulants, preservatives, flavors, juices, and color. 

Supercriticalfluid solvents are those formed by operating a system above the critical conditions of the solvent. SolubiHties of many solutes ia such fluids often is much greater than those found for the same solutes but with the fluid at sub atmospheric conditions. Recently, there has been considerable iaterest ia usiag supercritical fluids as solvents ia the production of certain crystalline materials because of the special properties of the product crystals. Rapid expansion of a supercritical system rapidly reduces the solubiHty of a solute throughout the entire mixture. The resulting high supersaturation produces fine crystals of relatively uniform size. Moreover, the solvent poses no purification problems because it simply becomes a gas as the system conditions are reduced below critical. 

Crystallization Solutes may be crystallized from supercritical fluids by temperature and/or pressure changes, and by the PCA process described above. In the rapid expansion from supercritical solution (BESS) process, a SCR containing a dissolved solute is expanded through a nozzle or orifice in less than 1 ms to form small particles or fibers. A variety of inorganic crystals have been formed naturally and synthetically in SCR water. 

This type of explosive behaviour is not to be confused with explosions such as drat of gunpowder, where the explosion is caused by the extremely rapid expansion of the gases which are liberated by chemical reaction widr a large release of heat. 

In many materials, the inherent flaws are easily recognized. Brittle polycrystalline materials, for example, contain microcracks, voids, and other imperfections that can be identified in micrographs, and are expected to provide sites for internal fracture activation. Artificial flaws introduced into a hollow metal shell by uniform scoring can be expected, under rapid expansion, to fracture the shell along the paths of scoring. 

Figure 8.12. Energy balance in catastrophic fragmentation, (a) Rapid expansion fragmentation and (b) Fragmentation Energy.

Buoyancy-induced dispersion, which is caused near the source due to the rapid expansion of the plume during the rapid rise of the thermally buoyant plume after its release from the point of discharge, should also be included for buoyant releases (15). The effective vertical dispersion cr is found from... 

Apart from deliberate spraying through small orifices, flammable, finely divided mist is most likely to be created by rapid cooling of hot vapor or rapid expansion of pressurized vapor. These form the basis of numerous experimental techniques for creating dense, almost monodispersed mists less than 10 /rm diameter. Condensation of hot oil vapor has commonly been... 

STEAM EXPLOSION Ovetpressure associated with the rapid expansion in volume on instantaneous conversion of water to steam. 

Confined vapour eloud explosion gas or vapour burns in a eonfined volume and rapid expansion of the eombustion produets is restrained until failure of the eontainer or building oeeurs. 

Pressure rupture, due to rapid release of high pressure. Blast is generated by rapid expansion of gas down to atmospherie pressure and rupture of the eontainer generates missiles. 

The internal friction due to vortices occurs in rapid expansion, diverging, and regulation valves. The entropy generation due to those vortices is taken into consideration in the local resistance. The entropy generation is directly proportional to c- thus. 

This section addresses the effects of BLEVE blasts and pressure vessel bursts. Actually, the blast effect of a BLEVE results not only from rapid evaporation (flashing) of liquid, but also from the expansion of vapor in the vessel s vapor (head) space. In many accidents, head-space vapor expansion probably produces most of the blast effects. Rapid expansion of vapor produces a blast identical to that of other pressure vessel ruptures, and so does flashing liquid. Therefore, it is necessary to calculate blast from pressure vessel mpture in order to calculate a BLEVE blast effect. 

The rapid expansion of a vessel s contents after it bursts may produce a blast wave. This expansion causes the first shock wave, which is a strong compression wave... 

The well-documented case of the United States serves as an illustration. During the period 1870 to 1900 the farm population was increased through a rapid expansion of the agricultural area. The agricultural labor force increased by 60 percent, but there was a replacement of labor by nonland capital in the form of horses and mules. New and more efficient types of horse-drawn machinery including plows, cultivars, seed drills, grain harvesters, and mowers became available. 

In conventional spraying paint is forced under pressure to the spray gun, where it mixes with air and, forced through a small orifice, atomises. Airless spray is created by forcing paint at extremely high pressures through an accurately designed small hole. Rapid expansion as it leaves the gun produces an extremely fine and very even spray pattern. No air is mixed with the paint before it leaves the gun, so avoiding dry spray . A wetter, heavier... 

The selection of the thirty procedures clearly reflects the current interest of synthetic organic chemistry. Thus seven of them illustrate uses of T1(I), T1 (III), Cu(I), and Li(I), and three examples elaborate on the process now termed phase-transfer catalysis. In addition, newly developed methods involving fragmentation, sulfide contraction, and synthetically useful free radical cyclization arc covered in five procedures. Inclusion of preparations and uses of five theoretically interesting compounds demonstrates the rapid expansion of this particular area in recent years and will render these compounds more readily and consistently available. 

Also noted is the rapid expansion of a number of materials produced by CVD, which include copper, tungsten, diamond, silicon carbide, silicon nitride, titanium nitride, and others. The coverage of the chemistry and deposition techniques of these materials has been greatly expanded. 

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