Hybrid layer structure

This highhght examines several new hybrid layered structures in the hetero-metallic perrhenate and vanadate families, whereby the late transition-metals are incorporated and their roles probed in the structures of layered solids. From these two families, new structural principles have emerged that not only help us understand key stractural features and correcdy forecast new compositions, but equally, have yielded many surprises (chirality, reduced phases) that show some of the most exciting chemistry is still waiting to be discovered or even imagined ... 

Allmann, R. (1977). Refinement of the Hybrid Layer Structure (Ca2Al(OH) ) (0.5SO4-3H2O)" . Neues Jahrbuch fur Mineralogie Monatshefte 4 136-144. 

Despite the fact that numerous coating materials are available, frequently, single layer structure of a coating does not meet the requirement. Composite coatings with multilayer structure or hybrid structure could sometimes provide peculiar properties. 

The flexibility of polyoxovanadate species [VxOy]" to adopt a wide variety of structural configurations, such as rings, chains, and layers, is reflected in their predominance in a wide variety of hybrid solids. For example, approximately sixteen distinct hybrid vanadium oxides based solely on V205 layers, with about nine different layer types, have currently been synthesized [34—47]. Layered structures of... 

Such layer structure does not allow ns to say a priori that hybridization of DNA will be possible, for it is protected by the octadecylamine layer. In order to control for this possibility, fluorescence measurements were performed. The first indication that hybridization was successful is that after the process, the sample surface became wettable, while before it and after cold hybridization it was not wettable at all. The results of the fluorescence measurements are summarized in Table 10. The results of the specific hybridization are three times more with respect to unspecific hybridization and one order of magnitude more with respect to cold hybridization. Thus, it appears that during a normal hybridization (100% homology) some structural changes and redistribution of the layer takes place. As a result, DNA becomes available for the specific reaction. Such a model also explains why the fluorescence level after unspecific hybridization (10% homology) is higher with respect to cold hybridization. Because the molecules have some mobility when the film is warmed, some DNA from the film could be hybridized on itself, while during cold hybridization this is impossible. 

The postulated existence of the oxysulfide MoOS can be ruled unlikely on the basis of the structures of Mo02 und MoS2. Molybdenum dioxide has a three-dimensional structure with distorted octahedral coordination (d2sp3 hybridization) about the molybdenum atoms12while MoS2 has a layer structure with a trigonal prismatic coordination about the molybdenum atoms (d4sp hydridization). Consequently, any existence of a MoOS species may be expected to be only transient. 

The formation and equilibrium structure of polymer layered silicate nanocomposites, in particular with organically modified layered silicates, has been shown to be a strong function of the nature of the polymer (polar or apolar), the charge carrying capacity of the layered silicate, as well as the chain length and structure of the cationic surfactant. However, both the polymer/silicate compatibility and hybrid equilibrium structure for these nanocomposites are observed to be independent of polymer molecular weight. The experimental results have been summarized by Vaia et al. and a lattice based mean field theory has been developed to explain these results [26]. 

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