General structural features

An effective comb LCP contains three primary structural variables each of which is significant to a realization of desired thermotropic behaviour, 

The backbones encountered are generally familiar in thermoplastics technology and tend to be flexible polymers associated with glassy, rubbery or fluid phases depending on temperature. Overwhelmingly dominant are polymethacrylates, polyacrylates and polymethylsiloxanes, in order of increasing chain flexibility (decreasing Tg). These and other comb LCP backbones are listed, with indicative references, in Table 7.1. 

As well as the constitution of the backbone, it is necessary to acknowledge the influence of details such as tacticity, polydispersity and molecular mass (e.g. average degree of polymerization, DP). Finally we will look 

The structural aspects of polyvalent iodine compounds were previously summarized in several books and reviews [20, 30, 32, 127]. In general, the molecular structure of and -iodanes is predetermined by the nature of hypervalent bonding discussed in Section 1.3. The key stmctural features of the hypervalent organoiodine compounds available from numerous X-ray data may be summarized as follows  

The I-C bond lengths in iodonium salts Ral X and X -iodanes RIX2 are approximately equal to the sum of the covalent radii of iodine and carbon, ranging generally from 2.00 to 2.10 A. 

Iodonium salts R2I+ X generally have a typical distance between iodine and the nearest anion X of 2.6-2.S A and in principle can be considered as ionic compounds with pseudo-tetrahedral geometry about the central iodine atom. However, with consideration of the anionic part of the molecule, the overall experimentally determined geometry is distorted T-shaped structure similar to the -iodanes RIX2. 

Owing to a highly polarized character of hypervalent bond, noncovalent attractive interactions of a predominantly electrostatic nature are exhemely important in the stmctural chemistry of hypervalent iodine 

Examples of both the intracellular and the extracellular proteins are shown in stereo in Fig. 2a and b. eLBPs are composed of about 175 amino acids, whereas the smaller iLBPs have about 130 residues. The slightly larger eLBPs are nearly spherical and have a diameter of about 40 A. The intracellular proteins have dimensions of about 25 x 35 x 40 A, giving them a more flattened appearance. As a result, they have occasionally been referred to as P clams. For all of the crystal structures of the iLBPs and most of the eLBPs that include bound ligand, the binding site has been localized to the inside of the barrel. 

Lipid-binding protein Abbreviation Resolution structure (A) Ref. 

Adipocyte lipid-binding protein ALBP 1.6 Xurtol. (1993) 

Keratinocyte lipid-binding protein MAL-1 Not determined Krieg et al. (1993) 

Heart fatty acid-binding protein HFABP 2.1 Zanotti et al. (1992) 

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This section will consider first the structure of pure metals and this will be followed by a description of the structure of alloys. In general, structural features will be discussed in order of increasing size, i.e. starting with atomic features and continuing through microscopic features to macroscopic features. 

General Structural Features. The general structure of halfsandwich ruthenium(II)-arene complexes is shown in Fig. 12. The structural, stereochemical and electronic features of metal-arene complexes have been discussed (63). A typical piano-stool geometry consists of an rj6-arene occupying three coordination sites of the pseudo-octahedral complex, leaving the three legs X, Y, and Z available for coordination. The sites X and Y can be taken up by two monodentate ligands, but are more commonly... 

General structural features of neurons are the perikarya, dendrites and axons 5... 

Fig. 2 General Structural Features of Pyrrole Containing Marine Natural Products...

Microtubules in the cytoskeleton and mitotic apparatus are also in a state of dynamic equilibrium and flux with unpolymerized tubulin, and tubulin appears to be an excellent example of the proteins which Pauling (1953) postulated to exist as globular protomers or as insoluble, fibrous, supramolecular structures akin to unpolymerized and polymeric hemoglobin S. The current view of the microtubule cytoskeleton in nondividing celb comes from the development of tubulin-specific antibodies for indirect immunofluorescent localization of microtubules (Fuller et al., 1975 Weber et al., 1975). The general structural features of such cyto-... 

To date, hundreds of organocopper species have been isolated and characterized. It is beyond the scope of this chapter to discuss the synthesis and structural characterization of these compounds in detail [29]. Here, general structural features, especially those associated with the reactivity of organocopper compounds, are discussed and illustrated by representative examples. 

The framework type codes accepted by the IZA Structure Commission gives a convenient way to discuss general structural features of materials but it is impor-... 

General Structural Features of Organized Molecular Monolayers. 241... 

The detailed analyses of renin-inhibitor complexes reported here confirm the general structural features thought to contribute to renin s specificity but... 

Although there are many hundreds of man-made dyes at the present time, it will be seen presently that most of these fall into a few large groups of structurally related molecules, the general structural features explaining their photostability. 

The notion of acids and bases is one of the first and most important ideas we are exposed to in chemistry, but it is one of the dtings that is often poorly understood. The concept is actually very simple if a few basic ideas are always kept in mind. The first things that must be remembered are the definitions of acids and bases and what general structural features make compounds react as acids or bases. 

Energy transfer measurements by McLendon et al suggest a Zn-Fe distance of ca. 17 A, in good agreement with Salemme s prediction. Thus the general structural features of the model appear to be well founded. 

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