Expanding core

The type of shelf design is the next consideration. The shelf can be a solid plate of plastic material, an inverted pan-like structure with reinforcing ribs, a sandwich-type structure with two skins and an expanded core, or even a lattice type sheet that has a series of openings. The choice between these is dictated by a number of factors. One is appearance or aesthetics. 

Major modification to areas adjoining hlling rooms (such as expanded core area)... 

As explained thoroughly in the original report, by careful comparison of the frequencies of these core-size markers with a series of structurally well-defined model compounds, the authors concluded that the photoproduct has a slightly expanded core relative to the deoxy structure and inferred that the probable cause for this expansion is restriction of the out-of-plane displacement of the iron brought about by protein restraint on the proximal histidine. Given this interpretation, it should be expected that significant differences in the iron-histidine stretching frequency are likely to be observed, and, as will be seen, it is indeed this feature which exhibits the most substantial shifts for these intermediate species. 

An unusual variation of the shrinking core model is the expanding core model in which the reaction starts at the center (see Doraiswamy and Gokarn, 1988). The product— ash core instead of the reactant core in normal behavior— moves outward till it completely envelops the particle. The controlling mechanisms described for the shrinking core model apply equally here, but the equations are different. We shall discuss this at some length later in this section while describing a model for the disproportionation of potassium terephthalate. 

With the chemical steps identified, detailed experimental studies were carried out by Doraiswamy and collaborators (Gokhale et al., 1975 Kulkarni and Doraiswamy, 1980 Revankar et al., 1987, Revankar and Doraiswamy, 1992) to elucidate the mechanism by which the solid particles of potassium benzoate behave during the reaction. The results, represented in Figure 15.8, reveal rather unusual behavior. The reaction starts at the center and proceeds outward till it is complete, thus conforming to the expanding core behavior mentioned earlier. 

Figure 15.8 The expanding core or rotting apple (because the apple rots from the center) model for fluid-solid reactions.

Figure 22.6 Guitar neck fabricated using expanded core technique. Source Reprinted with permission from George J, Technology puts carbon fibre into mass markets, Eureka, Franks-Hall, 35-37, Mar 1985. Copyright 1985, Franks Hall.

Jonsson, M., Nordin, O., Malmstrom, E., and Hammer, C. (2006) Suspension polymerization of thermally expandable core/shell particles. Polymer, 47, 3315-3324. 

Peixoto, L.S., Melo, P.A., Nele, M., Pinto, J.C., 2009. Expanded core/sheU poly(vinyl acetate)/ poly(vinyl alcohol) particles for embolization. Macromolecular Materials and Engineering 294,463 71. 

EM-3 120 C cure expanding epoxy film, with EM-3N being a natural colour formulation EM-5 230°C cure, expanding polycyanate film EM-6 95°C cure, expanding core splice epoxy film... 

In the field of compressed gases and related equipment, there is an expanding core of essential knowledge that people handling and using these materials should be familiar with or should know where to find. 

The ball catch with flash in Figure 5.40 is formed by an expanding core. The flash elimination in expanding cores is always very complex because it has to be coordinated in three dimensions. If the undercuts can be shaped with simple sliders, this soiution should be preferably chosen. 

Tamhurmo, C. et al.. Procedural success and 30-day clinical outcomes after percutaneous aortic vahre replacement using current third-generation self-expanding Core Valve prosthesis. / Invasive Cardiol, 2009. 21(3) p. 93-8. 

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