Backbone structure cluster structures

Figure 4.2 The mode of interconnection of clusters in amylopectin through (a) the traditional cluster structure and (b) the two-directional backbone structure. Boxes symbolize clusters with short chains (gray lines) indicated in some clusters. Black lines are chains involved in cluster interconnection. In (b) the B1-chains are the longest types of B1-chains with DP 25-35. The C-chain carries the reducing end-residue (0).

Previous work (11-16) has regarded the negative ion SSIMS spectra as relatively uninformative in comparison to positive ion emission. In this study we confirm very recent findings (18) that important information on side chain and backbone structure may indeed be obtained on analysis of the negative cluster ions which both compliments and clarifies information previously only obtainable from positive ion emission. The negative ion SSIMS spectrum shows a large amount of structural information without the confusing presence of intense C H species which abound in the positive ion spectrum. 

Sequence analyses of the Y. pseudotuberculosis O antigen gene clusters between hemH and gsk revealed a pattern of modules for different backbone structures and for different sidebranch sugars, with indications of homologous recombination events during evolution of the diversity (Skurnik et al., 2000 Pacinelli et al., 2002 ... 

Note that the fractal dimensions discussed here are the fractal dimensions of the excitation transfer paths connecting the hydration centers located on the inner surface of the pores. Due to the low humidity, all of the water molecules absorbed by the materials are bound to these centers. The paths of the excitation transfer span along the fractal pore surface and depict the backbone of clusters formed by the pores on a scale that is larger than the characteristic distance between the hydration centers on the pore surface. Thus the fractal dimension of the paths Dp approximates the real surface fractal dimension in the considered scale interval. For random porous structures, Dp can be also associated with the fractal dimension D, of the porous space Dp = Dr. Therefore, the fractal dimension Dp can be used for porosity calculations in the framework of the fractal models of the porosity. 

The bacterial ferredoxin from Pseudomonas aerogenes [now called Peptococcus assaccharolyticus] (P. a.) was crystallized and its three-dimensional structure first determined by Adman, Sieker and Jensen ° at 2.8 A resolution in 1973. The backbone structure model of P. aerogenes ferredoxin (abbreviated as P.a.-Fd) is shown in Fig. 9, below. The shape of the molecule is approximately a prolate ellipsoid, with a minor axis of 22 A and a major axis of 27 A, and with the centers of the two [4Fe 4S] clusters 12 A apart. 

Nafion samples can absorb several water molecules per acid or salt group. Because of the tetrafluoroethylene backbone structure, a good contrast exists between the water molecules and the polymer matrix. It is therefore possible to explore water clustering in these materials. 

The formation of clusters will be driven by electrostatic interactions between multiplets. The nature of these interactions is governed by cluster structure. It is envisioned that cluster formation proceeds as follows. A multiplet of maximum size, approximately eight ion pairs, is completely coated with a hydrocarbon skin . Therefore it is impossible for another multiplet to approach to a distance less than the thickness of a hydrocarbon chain, even though the multiplet of maximum size is expected to attract other multiplets through electrostatic interactions. Thus the cluster consists of a central core composed of a multiplet of maximum size surrounded at a distance by other multiplets of various sizes from ion pairs upwards. The size of the cluster is limited by the elastic forces arising from the backbone chain, which tend to pull the cluster apart. 

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