Further 3-dimensional Structural Elements

Another example of 2-dimensional infinite linking of octahedra, sharing edges in the one and comers in the other dimension, has recently been found in the ternary oxide CalrOa 262). No examples of isostructural fluorides are known, however. 

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The influence of plastic deformation on the reaction kinetics is twofold. 1) Plastic deformation occurs mainly through the formation and motion of dislocations. Since dislocations provide one dimensional paths (pipes) of enhanced mobility, they may alter the transport coefficients of the structure elements, with respect to both magnitude and direction. 2) They may thereby decisively affect the nucleation rate of supersaturated components and thus determine the sites of precipitation. However, there is a further influence which plastic deformations have on the kinetics of reactions. If moving dislocations intersect each other, they release point defects into the bulk crystal. The resulting increase in point defect concentration changes the atomic mobility of the components. Let us remember that supersaturated point defects may be annihilated by the climb of edge dislocations (see Section 3.4). By and large, one expects that plasticity will noticeably affect the reactivity of solids. 

Another approach is to map the arrangement of secondary structural elements onto the known tertiary structures of other proteins. Currently, approximately one hundred unique protein folds have been identified. There is some question as to if this is an upper limit. If this is indeed the case, then the protein of unknown structure must adopt a known topological fold. The secondary structural elements are mapped onto the template of the different known protein structures. The best fits, as judged by the environmental factors (solvent accessibility) of the individual amino acids, are then further analyzed as probable folds. This procedure is referred to as threading the secondary elements into three-dimensional structures [28],... 

A further enhanced degree of reduction leads to chains of group 14 elements with Ne values between 6 and 6.6 e/atom. These values cover the range between twofold bound silicon atoms in one-dimensionally extended zigzag chains and 2 dumbbells. Isolated chains reside in between these border structures and therefore compete with them [14]. This leads to the expectation of an extreme cation size dependence of the anion formation. Table 4 contains the reported isolated homoa-tomic chains in solid state compounds. 

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