Core regions

In the pseiidopotential construction, the atomic wavefrmctions for the valence electrons are taken to be nodeless. The pseiido-wavefrmction is taken to be identical to the appropriate all-electron wavefimction m the regions of interest for solid-state effects. For the core region, the wavefimction is extrapolated back to the... 

Basis sets can be constructed using an optimisation procedure in which the coefficients and the exponents are varied to give the lowest atomic energies. Some complications can arise when this approach is applied to larger basis sets. For example, in an atomic calculation the diffuse functions can move towards the nucleus, especially if the core region is described... 

CREN Available for SC(4.v) through Hs(0.v6/)6d), this is a shape-consistent basis set developed by Ermler and coworkers that has a large core region and small valence. This is also called the CEP—4G basis set. The CEP—31G and CEP—121G sets are related split valence sets. 

CRENEL Available for H(4v) through Hs(0.v3/i6r/5/), this is a collection of shape-consistent sets, which use a large valence region and small core region. 

Cables with multiple-layer sheathing have plastic-insulated cores. Solid PE or sintered PE is used as the plastic. Sintered PE is a foamed polyethylene material that has different electrical properties than solid PE. Under certain circumstances the core region is filled with a petrolatum material to give protection against... 

There are two main classes of loop modeling methods (1) the database search approaches, where a segment that fits on the anchor core regions is found in a database of all known protein structures [62,94], and (2) the conformational search approaches [95-97]. There are also methods that combine these two approaches [92,98,99]. 

Third, in open-sheet structures the a helices are packed against both sides of the p sheet. Each p strand thus contributes hydrophobic side chains to pack against a helices in two similar hydrophobic core regions, one on each side of the p sheet. 

The number of possible ways to form antiparallel p structures is very large. The number of topologies actually observed is small, and most p structures fall into these three major groups of barrel structures. The last two groups—the Greek key and jelly roll barrels—include proteins of quite diverse function, where functional variability is achieved by differences in the loop regions that connect the p strands that build up the common core region. 

Homologous proteins have similar three-dimensional structures. They contain a core region, a scaffold of secondary structure elements, where the folds of the polypeptide chains are very similar. Loop regions that connect the building blocks of the scaffolds can vary considerably both in length and in structure. From a database of known immunoglobulin structures it has, nevertheless, been possible to predict successfully the conformation of hyper-variable loop regions of antibodies of known amino acid sequence. 

Even-tempered basis sets have the same ratio between exponents over the whole range. From chemical considerations it is usually preferable to cover the valence region better than the core region. This may be achieved by well-tempered basis sets. The idea is similar to the even-tempered basis sets, tire exponents are generated by a suitable formula containing only a few parameters to be optimized. The exponents in a well-tempered basis of size M are generated as ... 

Kir 1.1. Bartter Syndrome. Several mutations in the core region as well as in the N and C terminus of Kir 1.1 are found in patients with hyperprostaglandin E syndrome (HPS renal disorder resulting from impairment of tubular reabsorption), an antenatal form of Bartter syndrome. Some of these mutations result in the loss of function of Kiri. 1 channels causing impaired renal K+ secretion and NaCl reabsorption. 

Dendrimers have distinctive properties, such as the ability to entrap small molecules in their core region and very low intrinsic viscosities in solution. Such properties require molecules to have achieved a particular size, and not all molecules with branches radiating from a core are large enough to develop the characteristic properties of true dendrimers. Branched molecules below this critical size are called dendrons and are the equivalent in dendrimer chemistry of oligomers in polymer chemistry. 

The basic idea of the pseudopotential theory is to replace the strong electron-ion potential by a much weaker potential - a pseudopotential that can describe the salient features of the valence electrons which determine most physical properties of molecules to a much greater extent than the core electrons do. Within the pseudopotential approximation, the core electrons are totally ignored and only the behaviour of the valence electrons outside the core region is considered as important and is described as accurately as possible [54]. Thus the core electrons and the strong ionic potential are replaced by a much weaker pseudopotential which acts on the associated valence pseudo wave functions rather than the real valence wave functions (p ). As... 

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