Shell fragmentation

Reservoir rocks are either of clastic or carbonate composition. The former are composed of silicates, usually sandstone, the latter of biogenetically derived detritus, such as coral or shell fragments. There are some important differences between the two rock types which affect the quality of the reservoir and its interaction with fluids which flow through them. 

Spreng-stUck, n. fragment (from bursting), specif, shell fragment, -technik, /. technics or manufacture of explosives, -trichter, m. explosion crater sprinkling rose. 

A short summary of the SCF-MI method is presented here for the simplest case of two interacting closed-shell monomers A and B. A full account of the theory is given elsewhere [11] and its generalization to interaction of an open shell with an arbitrary number of closed shell fragments has recently appeared [19]. 

BSSE also opposes the tendency of the Hartree-Fock model to keep the interacting closed shell fragments too far apart. So, when optimized geometries are considered for the complex, BSSE is found to mimic some of those effects on the electron density distribution which would be induced by the interfragment dispersion contributions. 

In certain problems of torsional isomerism we shall employ the dissection of a molecule A-B into two closed shell fragments A and B. On the other hand, most problems of torsional isomerism which we shall be dealing with in the first part of this work can be treated by employing the dissection shown below. The appropriate definitions are specified in parenthesis. 

However, the two electron stabilizing interaction dominates the four electron destabilizing interaction. Thus, cis union will be more favorable than trans union. In other words, here we have an application of the regiochemical rule stating that the union of two open shell fragments having a total of 4N + 2 pi-electrons will be predisposed to be cis. 

Let us study a system constituted of K fragments Qi. ..flAr We assume that the first (K-1) fragments are closed-shell systems described by doubly occupied orbitals. The last fragment Ok has an open-shell configuration, consisting of singly occupied molecular orbitals of parallel spin. Obviously, the theory here developed can easily be restricted to the case of K closed-shell fragments. 

Distribution of Shell Fragment Masses. One ref is listed in Vol 1, p XI. See also under Fragmentation Test... 

The dune sand generally consists of fine well-rounded grains shaped by the action of the wind. It is composed mostly of quartz with small percentages of soft calcareous shell fragments and gypsum pellets (12). 

Note Compns, designated Ammonex K and L, were also developed with tetryl added in amounts equivalent to those of the Ammpierateusedin the above mixts. These mixts were not superior to those contg Ammpicrate when subjected to shell fragmentation tests... 

Distribution of Shell Fragment Masses was dctd at ERL, Brucetoa, Pa by firing shells in a Fragmentation Pit filled with sawdust. The fragments were recovered by a magnetic separator. Details of procedure are given in OSRD Kept 5607< 1945) See also OSRD Rcpts 5606 and 5608 Drop Test Same as Impact Sensitivity Test... 

This type of work continued and is reported on in Ref 50. A modified Compn B was developed which had a cast density of 1.64g/cc, is equivalent to Compn B in the sand test, is slightly inferior to Compn B in the shell fragmentation test, but is comparable with TNT in impact and rifle bullet sensitivity. This compn is composed of 60/32/8 RDX/TNT/N-octadecyl phthalimide. It was recommended that this compn be evaluated in components where Compn B is normally used... 

Figure 4.85 Example of a radical dissociation reaction yielding a smaller free radical and a closed-shell fragment...

Refs 1)F.R.Benson, "Study Properties of RDX Composition C-2 , PATR 1293 (1943) 2)F.R. Benson, "Suitability of Composition C-3 as a Plastic Explosive," PATR 1416 (1944) 3)Anon "Data on Foreign Explosives", US Chemical Warfare Service Field Lab Memo 4-6-2, US Office of Technical Services PB Report 11544 (1944) 4)L.H.Eriksen, "Effect of Storage on the Sensitivity of Compositions C, C-2, C-3 and PEP-2D" PATR 1518 (1945) 5)A11 En Expls (1946), 125-28 6)Anonymous, Ordn 30, 102 (1946) 7)S. Fleischnick, "Evaluation of Explosives Based on Shell Fragmentation," PATR 1595 (1946)... 

Identification of Shells and Shell Fragments , US Armed Forces Far East (1954) 30) T. 

Shell Fragmentation. See subjects from Fragmentation thru Fragment Velocity Measurements in Vol 6, F180-L to F182-L... 

Precipitated compounds Carbonates (including shell fragments)... 

Properties Yellow crystals. Sp. gr. 1.69 at 20°. M. P. 121.2°. More powerful and having higher hri-sance than TNT, but producing smaller shell fragments. Less sensitive to impact and more toxic than TNT. Rate of detonation (d = 1.66) 7350 m/sec., compared with 7140 m/sec. for TNT (d = 1.60) when tested under similar conditions. 

Cavaliere, A. R. Alberte, R. W. (1970). Fungi in animal shell fragments. Journal of the Elisha Mitchell Scientific Society, 86, 203-6. 

Based on these kinetic and microscopic observations, olefin polymerization by supported catalysts can be described by a shell by shell fragmentation, which progresses concentrically from the outside to the centre of the support particles, each of which can thus be considered as a discrete microreactor. A comprehensive mathematical model for this complex polymerization process, which includes rate constants for all relevant activation, propagation, transfer and termination steps, serves as the basis for an adequate control of large-scale industrial polymerizations with Si02-supported metallocene catalysts [A. Alex-iadis, C. Andes, D. Ferrari, F. Korber, K. Hauschild, M. Bochmann, G. Fink, Macromol. Mater. Eng. 2004, 289, 457]. 

Since the dissociation energy of X 2 ArF (reaction 6) represents a homolytic bond cleavage with the transition of a closed-shell species into two open-shell fragments, the Z) value... 

After the nuts are cracked, they drop into rotary screens where some separation of kernels and shells is obtained. Some shell fragments, however, cannot be separated by screening. They also are too heavy to be removed by air separation... 

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