Recombination structures

A few selected types of such relationships between different structures will be presented in this paragraph and in the following ones ( 3.9 and 3.10). Examples will be considered of possible (virtual and/or real) transformation mechanisms from one structure type to another (degenerate, derivative structures) examples will also be discussed of groups of structures interrelated because based on the assembly of similar blocks and fragments (recombination structures). 

STRUCTURE FAMILIES RECOMBINATION STRUCTURES , MODULAR ASPECTS OF CRYSTAL STRUCTURES... 

Strictly related to this kind of description are the concepts of Recombination Structures and of Intergrowth Structure Series, to be discussed in the following see 3.9.4. 

Examples of common structure types and of their characteristic fragments In Chapter 3 it was underlined that several interrelations between different structures may be described in terms of recombination structures , evidencing the structural... 

In practice, recombination of structure factors involves first weighting of the phases of the modified structure factors in a resolution dependent fashion, according to their estimated accuracy or probability. Every phase also has an experimental probability (determined by experimental phasing techniques and/or molecular replacement). The two distributions are combined by multiplication, and the new phase is calculated from this combined probability distribution. The measured associated structure factor amplitude is then scaled by the probability of the phase, and we have our set of recombined structure factors. 

There are, however, a number of facts which make such a proposal untenable. In the first place, the fact that disproportionation is much faster than recombination by a factor of 3.2 for fer -butyl radicals indicates that such structures cannot be general since this would imply that for steric repulsion of CH3 groups lowers the recombination efficiency but does not affect the disproportionation rate which goes through a different transition state. 

Kudoh (2002) proposed a possible structure for hydrous olivine that is a recombination structure... 

Ruffing M, Zentgraf H, Kleinschmidt JA. Assembly of viruslike particles by recombinant structural proteins of adeno-associated virus type 2 in insect cells. J Virol 1992 66 6922-6930. 

Protein engineering allows the preparation of monodisperse, high molecular weight polypeptides with complete sequence control. It has been successfully used for the construction of recombinant, structural proteins, such as... 

Crystal structures of a large number of complex sulfides can be described as composed of rods, blocks or layers of simple, archetypal structures that are joined (recombined) in various ways by the action of one or more structure-building operators, such as the various kinds of unit-cell twinning. The resulting structures were denoted as the recombination structures by the Subcommittee on the Nomenclature of Inorganic Structure Types (Lima-de Faria et al., 1990). It is this kind of complex sulfides we deal with in the present review those with complex chemistry but simple structural principles (e.g., the substitution-, interstitial- or omission derivatives of archetypal stmctures) are not included. 

The principal sulfide family with recombination structures are the so-called "sulfosalts". They are defined as complex sulfides (rarely also selenides and tellurides) AyB S. 

At the small-scale level, the crystal chemistry of sulfide recombination structures is determined by the easy and variable combinations of fundamental coordination polyhedra, yielding both the blocks of archetypal structures and the configurations on... 

For the recombination structures aggregation is typical of a number of coordination polyhedra Into rods, blocks or layers with internal structure similar to a simple archetypal structure. 

Figure 17. A non-commensurate, layer misfit structure (o), composed of alternating layers of two types, and the recombination structures (i-iii) derived from (o) by means of (i) composition-conservative and of (ii-iii) two kinds of composition non-conservative antiphase boundaries (or glide planes), (iv) A layered non-commensurate structure with corrugated layers that are composed of alternating strips of two kinds that exhibit layer misfit on interfaces.

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