Silica fibrous

Finally, a very low-density form of fibrous silica, W-Si02 has been made by the disproportionation of (metastable) crystalline SiO ... 

Eisen-alaun, m. iron alum (ferric potassium sulfate), -amiant, m. (Iron) fibrous silica.. ammonaiauQ, m. ammonium ferric alum.. ammonaiaunldsuQg, /. solution of ammonium iron salt, esp. ammonium ferric alum. -antimonerZ) n., -antimonglanz, m. berthier-ite. 

Tamaru S, Takeuchi M, Sano M, Shinkai S (2002) Sol-gel transcription of sugar-appended porphyrin assemblies into fibrous silica unimolecular stacks versus helical bundles as templates. Angew Chem Int Ed 41 853-856... 

Siltemp [Ametek], TM for a substantially pure fibrous silica for use in rocket and missile construction and for high-temperature insulation of motor components and similar applications. 

Glasses are three-dimensional polymers whereas fibrous or ladder silica is linear and unidimensional. Fibrous silica readily reacts with water or alcohol, forming metasilicic acid or a polymeric ester of metasilic acid ... 

It is important to realize that mechanical properties can also be critical in non-structural applications. For example, in the design of the thermal protection system of the space shuttle, highly porous, fibrous silica tiles are used. The microstructure of these materials, shown in Fig. 1.1, consists of a bonded array of fibers, usually based on silica glass. Clearly, the prime reason for using these materials was their low thermal conductivity but the resistance to thermal and structural stresses was a key item in the final design. In some non-structural applications, mechanical properties can be important in determining the lifetime... 

Figure 1.1 Microstructure of space shuttle tile material, a high-porosity fibrous silica secondary electron image using the scanning electron microscope (SEM). (Reproduced courtesy of Plenum Press, New York.)...

Anhydrous fibrous silicas formed in connection with high temperature metallurgical operations were noted as long ago as 1852 by Schnabel and 1859 by Rose. Soft, silky fibers of more than 98% SiO, were classed as aphanitic (invisible) silica, and also known as lussatite. Around 1910. in the mouths of electric furnaces making silicon carbide, a soft spongy gray deposit called elephant s ear" was identified as microfibrous amorphous silica (67). It is likely that all of these were silica W. 

Silicon monoxide has long been known to oxidize to fibrous silica. Nemetschek and Hofmann (102) investigated the material condensed from vapor from the reaction of silica and silicon metal. Under the electron microscope it was found to consist of a mat of remarkable hollow tubes and spiral fibers of amorphous silica less than 0.04 micron in diameter and many microns long. The morphology was compared with the fibers of halloysite and chrysotile (103). 

To overcome the problems of gas-sensor failure due to poisoning of the elements, several manufacturers have used specific filter devices in front of the elements. For example, filters to remove alkyl lead compounds from petrol vapour have included paradichlorobenzene and fibrous silica (3). However, the most commonly used material is based on active charcoal. Such filters (4) effectively absorb many common poisons and inhibitors including silicones, alkyl lead compounds and halogen-containing species. However, along with the absorption of potentially harmful vapours, carbon filters will also absorb hydrocarbons. This effect in practice limits the use of such filters to detectors for C3 and lower hydrocarbons. They cannot be employed in general flammable gas detectors. 

Other molecules present in the gas mixtures like alcohols or ketones may have a moderate effect on aromatic oxidation but the reverse (inhibition of alcohol oxidation by aromatics) is most often observed. Different supports of Pt were used for toluene oxidation Al203, Al203/Al, Zn0/Al203, Ti02, mesoporous fibrous silica or monoliths. Zeolites, generally promoted by platinum, were shown to give excellent catalysts for aromatic oxidation. Basic zeolites showed excellent performances in oxidation of m-xylene even in the absence of platinum. Palladium catalysts, either supported on alumina or ceria-alumina, were also investigated for oxidation of benzene and several alkylbenzenes. ... 

Uchisawa, J., Kosuge, K., Nanba, T., et al. (2009). Effect of meso- and macropore structures of Pt-supported fibrous silica on the catalytic oxidation of toluene, Catal. Lett., 133, pp. 314-320. 

Chimeric (fusion) proteins that incorporate the R5 peptide have been synthesized to control and precipitate silica nanoparticles. Po Foo and coworkers have utilized a two-component chimeric protein consisting of the R5 polypeptide (from C. fusiformis) and the self-assembling domain based on the consensus repeat in the major ampullate spidroin protein 1 (MaSpl) of Nephila clavipes spider dragline silk [64]. MaSpl forms highly stable P-sheet secondary stmctures that can be spun into intricate fibers which, when fused with the sihca-templating R5-peptide, allow for the formation of film-like and fibrous silica structures (Figure 1.18). 

Peng H-g XuL, Wu H, Zhang K, Wu P (2013) One-pot synthesis of benzamide over a robust tandem catalyst based on center radially fibrous silica encapsulated TS-1. Chem Common 49 (26) 2709-2711... 

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