Inorganic layers

17 Sensing Layers in Work-Function-Type Gas Sensors 

Other inorganic materials were also studied by KP. Studies on gas sensitivity are reported for carbonates, especially BaCOj, being sensitive to CO and NO even at ambient temperature (Ostrick et al. 1999, 2000a, 2003), TiN (Ostrick et al. 2000b) as ammonia sensitive layers, and LaFj as oxygen (Cho et al. 1991 Choi et al. 1993) and ozone (Doll et al. 1996) sensing layers. The sensitivity of barium carbonate to CO in work-function-type gas sensors is due to the formation of bicarbonate 

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The silver(I) complexes with the tetrakis(methylthio)tetrathiafulvalene ligand have been reported, the nitrate salt presents a 3D structure with an unprecedented 4.16-net porous inorganic layer of silver nitrate,1160 the triflate salt presents a two interwoven polymeric chain structure.1161 The latter behaves as a semiconductor when doped with iodine. With a similar ligand, 2,5-bis-(5,5,-bis(methylthio)-l,3,-dithiol-2 -ylidene)-l,3,4,6-tetrathiapentalene, a 3D supramolecular network is constructed via coordination bonds and S"-S contacts. The iodine-doped compound is highly conductive.1162 (Methylthio)methyl-substituted calix[4]arenes have been used as silver-selective chemically modified field effect transistors and as potential extractants for Ag1.1163,1164... 

The assembly of biopolymers with inorganic layered solids can lead to bionanocomposites in which the biopolymer becomes intercalated between the layers of the inorganic hosts [3]. The intercalation is a complex process that may simultaneously involve several mechanisms. Thus, in addition to hydrogen bonding, it has been invoked that certain biopolymers interact with the inorganic layers through... 

In the next section, we demonstrate how exfoliation and ordered restacking of aminopropyl-derivatized magnesium phyllosilicates in the presence of proteins, enzymes or DNA can be used to prepare new types of bio-inorganic layered nanocomposites. 

In conclusion, we have highlighted in this and the preceding section two versatile synthetic strategies to bio-inorganic layered nanocomposites based on the self-assembly of organically functionalized magnesium phyllosilicates (Figure 8.18). 

Choy, J.H., Kwak, S.Y., Jeong, Y.J. and Park, J.S. (2000) Inorganic layered double hydroxides as nonviral vectors. Angewandte Chemie-Intemational Edition, 39, 4042-4045. 

Nanoparticles such as those of the heavy metals, like cadmium selenide, cadmium sulfide, lead sulfide, and cadmium telluride are potentially toxic [14,15]. The possible mechanisms by which nanoparticles cause toxicity inside cells are schematically shown in Fig. 2. They need to be coated or capped with low toxicity or nontoxic organic molecules or polymers (e.g., PEG) or with inorganic layers (e.g., ZnS and silica) for most of the biomedical applications. In fact, many biomedical imaging and detection applications of QDs encapsulated by complex molecules do not exhibit noticeable toxic effects [16]. One report shows that the tumor cells labeled with QDs survived in circulation and extravasated into tissues... 

Fig. 10 (a) Structure of the mixed valence compound [Cun(hfac)2(TTF—CH=CH—py)2] (PF6) -2CH2C12, showing alternating organic/inorganic layers with the PF6 anions incorporated in the TTF layer, (b) Projection in the ab plane showing the separation of the TTF dimers by the PFfi- anions... 

Structural aspects of these nanoparticles are also discussed in this chapter. Extensive mathematical research has been devoted to polyhedramade of a single layer (13). Surprisingly, however, mathematical analysis of polyhedra and nanotubular structures made of two interconnected layers and more has started only very recently, as a result of the discovery of IF phases [see, e.g., (14)]. Most of the inorganic layered materials are comprised of more than one atomic layer, with strong chemical bonds interconnecting between the atoms of the different layers. Therefore a mathematical analysis of multilayer polyhedra is called for. 

Modification of Materials by Deposition of Organic or Inorganic Layers 67... 

Heteropolyacids are frequently used to modify proton-conducting composites,or they are just dispersed in inert matrixes.However, because the proton conduction mechanism of such hydrated salts is similar to those of hydrated polymeric sys-tems, these composites show qualitatively similar transport properties. The same is true for organically modified inorganic layered compounds such as titanium phosphate sulfophenylenphosphonate, the conductivity of which is dependent on the RH value, in a manner similar to that observed with Nafion. ... 

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