Topologies cylindrical

Storkle D, Duschner S, Heimann N et al (2007) Complex formation of DNA with oppositely charged polyelectrolytes of different chain topology cylindrical brushes and dendrimers. Macromolecules 40 7998-8006. doi 10.1021/ma0711689... 

Some of the more remarkable examples of this form of topologically controlled radical polymerization were reported by Percec et cii.231 234 Dendron maeromonomers were observed to self-assemble at a concentration above 0.20 mol/L in benzene to form spherical micellar aggregates where the polymerizable double bonds are concentrated inside. The polymerization of the aggregates initiated by AIBN showed some living characteristics. Diversities were narrow and molecular weights were dictated by the size of the aggregate. The shape of the resultant macroniolecules, as observed by atomic force microscopy (ATM), was found to depend on Xn. With A, <20, the polymer remained spherical. On the other hand, with X>20, the polymer became cylindrical.231,232... 

The analytical structural model for the topology of the nanostructure is defined in Isr (5). For many imaginable topologies such models can be derived by application of scattering theory. Several publications consider layer topologies [9,84,231] and structural entities built from cylindrical particles [240,241], In the following sections let us demonstrate the principle procedure by means of a typical study [84],... 

Furthermore, Oda et al. pointed out that there are two topologically distinct types of chiral bilayers, as shown in Figure 5.46.165 Helical ribbons (helix A) have cylindrical curvature with an inner face and an outer face and are the precursors of tubules. These are, for example, the same structures that are observed in the diacetylenic lipid systems discussed in Section 4.1. By contrast, twisted ribbons (helix B) have Gaussian saddlelike curvature, with two equally curved faces and a C2 symmetry axis. They are similar to the aldonamide and peptide ribbons discussed in Sections 2 and 3, respectively. The twisted ribbons in the tartrate-gemini surfactant system were found to be stable in water for alkyl chains with 14-16 carbons. Only micelles form... 

It has been suggested that the Sup35p filament may be a bundle of four cylindrical //-sheets or nanotubes (Kishimoto et al., 2004). The nanotube is a hypothetical structure (Perutz et al, 2002) whose winding of the polypeptide chain is topologically similar to that of a //-helix but it is round in cross section and water filled whereas //-helices have cross sections with triangular or other shapes and water is largely excluded from their interiors (Kajava and Steven, 2006). The model of Kishimoto et al. envisaged six coils... 

Most of the antiparallel /3 domains have their sheets wrapped around into a cylinder, or barrel, shape. None of the antiparallel barrels has as symmetrical or as continuously hydrogen-bonded a cylindrical sheet as the singly wound parallel fi barrels of triosephos-phate isomerase and pyruvate kinase dl however, antiparallel barrels are very much more common. Because of gaps in the hydrogenbonding, some of these structures have been described as two /3 sheets facing each other (e.g., Schiffer et al., 1973 Blake et al., 1978 Harrison et al., 1978). Our reasons for treating them all as barrels are that the gap positions are sometimes different in domains that are probably related, and that the barrel description yields very much simpler and more unified topologies. 

Most of the metal-rich proteins form approximately cylindrical two-layer structures with either an up and down (rubredoxin, cytochrome c) or a Greek key (ferredoxin) topology, but in which the elements forming the cylinder are a mixture of helices, /3 strands, and more or less extended portions of the backbone. Cytochrome c3 is perhaps the ultimate example of an S-M protein, with four hemes in just over a hundred residues, and essentially no secondary structure at all except for one helix. 

Cryptands, 42 122-124, 46 175 nomenclature, 27 2-3 topological requirements, 27 3-4 Cryptate, see also Macrobicyclic cryptate 12.2.2], 27 7-10 applications of, 27 19-22 cylindrical dinuclear, 27 18-19 kinetics of formation in water, 27 14, 15 nomenclature, 27 2-3 spherical, 27 18 stability constants, 27 16, 17 Crystal faces, effect, ionic crystals, in water, 39 416... 

Cylindrical cryptands have been receiving increasing interest recently as multidentate ligands with novel topological properties and also as potential chelates for two metal atoms (80PAC2441). 

Macrotricyclic cryptates may have either spherical or cylindrical topology (90). The cylindrical ligands, such as 5, are formed by linking together two macrocycles and define three cavities, two lateral and one central cavity inside the macrotricycle (18,19,91, 92). The macrotricyclic ligands of spherical topology are Particularly well suited for com-plexation of alkali cations as they define a spherical cavity (93, 94). Ligand 10, for example, contains a spherical cavity (diameter 3.4 A)... 

Closed ft a [l Barrel Structures. Chicken triose phosphate isomerase (Figure 12.lj) is typical of a large number of structures that contain eight (S-tx. units in which the strands form a sheet wrapped around into a closed structure, cylindrical in topology. The helices are on the outside of the sheet. 

In the described cylindrical topology (see Figure 11.12), the modeling of the DLC internal construction has given a heat transfer coefficient of 12W/m2/K. The radial thermal conductivity is equal (o 7 = 0.5 W/m/K and is much smaller than the axial thermal conductivity which is equal to... 

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