Structure decomposition

Only two oxides of cobalt have been characterized, CoO and Co304 (which is actually ConConl04). The latter has a structure in which Co2+ ions are located in tetrahedral holes and Co3+ ions are located in octahedral holes of a spinel structure. Decomposition of either Co(OH)2 or CoC03 produces CoO, and decomposition of Co(N03)2 can be used to produce Co304. 

The partial structural decomposition of the POM, as evidenced by (i) the formation of small amounts of crystalline M0O3, and (ii) the change in the cationic composition. In regard to the latter point, the ammonium content in the catalyst decreased, and its place in the cationic position of the POM was occupied by Mo ions. The formation of Mo dimeric species was shown in the downloaded catalysts, which were made of neighboring Mo ions located in the anion and in the counteranion cationic position." ... 

These phenomena occurred only when isobutane-rich conditions were used. Indeed, when the reaction was carried out under isobutane-lean conditions (e.g., with 1% isobutane in the feed), the partial structural decomposition and the reduction of the POM did not occur, and similarly the changes in catalytic performance also were not observed, but there was a minor change in selectivity to methacrylic acid. This means that the reduction of the POM was due to the isobutane-rich conditions, and that the structural decomposition was due to the larger amount of reaction heat released at the catalyst surface under these conditions. Overheating of the catalyst particles took place, with temperatures that favored the incipient structural decomposition of the POM. 

Sun L, Shelnutt JA (2005) Normal-coordinate structural decomposition engine 3.0. http //jas-heln.unm.edu/jasheln/content/nsd/NSDengine/nsd index.htm. Last accessed 30 April 2008... 

Examples of weight loss or weight gain processes are water desorption, structural water release, structural decomposition, carbonate decomposition, gas evolution, sulfur oxidation, fluoride oxidation, rehydration, and other transformations. 

Retrograde Diels-Alder reactions are unlikely reactions in coal liquefaction chemistry due, again, to the lack of suitable molecular structures. Decomposition of cyclohexene to ethylene and 1,3-butadiene, for instance, is 40 kcal/mol endothermic and at 450°C proceeds at a rate such that the half-life of cyclohexene is 13 hours (11a). For tetralin to react by an analogous reaction, resonance stability would be lost, and the reaction would be many orders of magnitude slower than cyclohexene. 

Jentoft et al. (2003) IR, UV-vis, XAS Heteropolymolybdates, vanadium substituted Phase dynamics, structural decomposition + + + Various partial oxidations and dehydrations... 

Fig. 2 a The detailed three-dimensional structure of crambin, a small (46-residue) plant seed protein (main chain in light gray, side chains in darker gray), b A cartoon view of the same protein. This view highlights the secondary structure decomposition of the structure with the two helices packing into each other along side a /1-sheet... 

Piasta et al. (P60) described the thermal eflfects on the cement paste. Below 500°C, major effects include carbonation and coarsening of the pore structure. Decomposition of CH at 450-550°C, and of CaCOj above 600 C, yield CaO, which rehydrates on cooling. The resulting expansion may disrupt a concrete that has withstood a fire without actual disintegration (L6). Above 500°C, the pore structure continues to coarsen, and incipient crystallization of P-C2S occurs. Extensive carbonation occurs in fire-damaged buildings that have been left standing for a few years (H71). 

Thus, mechanical activation of a mixture of silicate phases of granite leads to their structural decomposition. Layered phases are destroyed more rapidly than framework ones. Besides, adsorb water is removed at lower temperature (200-300°C). Thermal treatment of mechanically activated mixture with CaO leads to the formation of minerals of cement clinker. 

Many past studies on the enzymes of lignin decomposition focused on phenol-oxidizing enzymes, such as laccase and peroxidase, produced by white-rot fungi. It is unlikely, however, that this type of activity is important in structural decomposition (33), although the enzymes may have some other role in lignin decomposition (28). 

As the sillimanite minerals are geologically formed at high pressures, they decompose or undergo a structural decomposition when heated to elevated temperatures in air at 1 atm pressure [7-10], The decomposition reaction can be written as... 

An important drawback of these systems, limiting their application as heterogeneous catalysts, consists in a long-term deactivation effect, related to the loss of molybdenum oxide (8) this occurs as a consequence of the primary structure decomposition. By supporting the heteropolycompound (5), or by co-feeding M0O3 in the reactor (8), improvements of the catalytic stability can be achieved. Moreover, the saUfication of the acid is known to lead to an increase in the stabihty of these compounds. 

Heteropolysalts with composition I (NH4)3-xPMoi2O40, prepared hy precipitation, showed a good catalytic activity and selectivity in IBA oxydehydrogenation over the short-term. Obtained results were comparable to the best ones reported in literature for heteropolyacids containing vanadium atoms. The catal rtic performance was relatively stable even after tretaments that led to partial structural decompositions. The cationic composition affected the catalytic performance the best results were obtained with the (NH4)3PMoi2O40 sample, characterized by a low specific surface area. 

All these data indicate that the progressive increase in activity during service time observed for the catalyst prepared at strongly acid pH (Figure 9) is due to the development of an active species during equilibration, which occurs as a consequence of partial structural decomposition of the POM and redistribution of molybdenum in the framework. This active species can be hypothesized to include Mo ions located in the cationic position of the framework. An additional phenomenon is the increase in the extent of reduction of the POM, which is in part responsible for the progressive increase in selectivity. 

Figure 4 Six out-of-plane vibrational coordinates of a Z)4h metalloporphyrin used in normal structural decompositions to reveal compositions of equilibrium out-of-plane heme deformations. Mulliken S5nnbols are of the I>4h point group and the abbreviations sad, ruf, dom, wav, and pro indicate saddled, ruffled, domed, wave, and propeller distortions, respectively. (Note that wav and waVy derive from a doubly degenerate pair of Eg vibrational modes of the porph5rin.) The dark and light circles indicate atoms on opposite sides of the mean heme plane. Adapted from ref. 11.

Regardless of the driving force(s), out-of-plane porphyrin deformations invariably occur along low-frequency, normal coordinates. A recent computational method, normal-coordinate structural decomposition (NSD), yields linear combinations of equilibrium distortions along the lowest-... 

Data/control flow diagrams (DFD/CFDs), which are enhanced with real-time extensions when used in conjunction with Petri nets, provide a suitable framework for concurrent specification of functional and real-time state logic. The main reason for this is the ability to maintain identical structural decompositions in both representations at aU levels of detail in the specification. This model is accomphshed by maintaining identical partitioning of processes in both specifications. 

Modeling Method for Function View Function view modeling normally uses the top-down structural decomposition method. The function tree is the simplest modeling method, but it lacks the links between different functions, especially the data flow and control flow between different functions, so it is generally used to depict simple function relationships. In order to reflect data and control flow relationships between different functions, SADT and IDEFO (Colquhoun and Baines 1991) methods are used to model function view. The IDEFO formalism is based on SADT, developed by Ross (Ross 1985). 

High degrees of grafting by the free-radical mechanism can be attained when polymerizations are initiated from the backbones of the polymer. One way this can be done is to form peroxides on the backbone structures. Decompositions of such peroxides can yield initiating radicals. Half of them will be attached to the backbones. An example is the preparation of graft copolymers of polysty-... 

This section summarizes the structure/decomposition correlations found in our work for various classes of energetic compounds. More details and justification for most of the results are contained in the original articles. 

All of the compounds liberating N2O have in common a -CH2- group straddled by two nitrogen atoms as shown by unit (2). No compounds lacking structural unit (2) produce N2O upon fast thermolysis. This feature appears to be the only structure/decomposition relationship pertaining to N2O formation. 

Several studies of other types of energetic functional groups have been undertaken. These are grouped here because less comprehensive studies of them were conducted owing to the unavailability of extensive sets of compounds. Selected studies merit mention even though the structure/decomposition relationships found are not especially broad. Studies are currently in progress on tetrazoles and triazoles, but the data are not sufficiently complete to discuss here. 

Furazan and Furoxan Containing Compounds. These energetic functional groups are interesting in their own right, but have also been identified in the thermal decomposition and sensitization of TATB [82]. Structure/decomposition relationships for benzofuroxan compounds were not decipherable in the set of compounds studied [83]. However, the results reveal distinctly different decomposition pathways for benzofuroxans and dialkylfuroxans. With benzofuroxans the benzene ring holds the furoxan... 

Combustion chemistry strongly depends on the gas molecules that leave the surface of the propellant. Section 3 of this article summarized most of the findings to date. Many of the small molecule products detected in our measurements are likely to be important in feeding the early flame zone. A practical use of the structure/decomposition relationships might then be to connect the synthetic organic chemist and propellant formulator to the combustion scientist. By knowing the flame characteristics of various gas combinations from the work of the combustion scientist, the desirable and undesirable combustion features could be tailored in and out by the synthetic organic chemist and formulator to produce the desired gas combinations. 

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