Quartz, fused

The gas chromatographic separation of some sulphoxide enantiomers was observed on quartz fused silica capillaries coated with the chiral silicon phase chirasil-val280. 

According to Gorbach, Weber (24) in 1892 was the first to substitute a quartz fused-on fiber for the knife-edge support of a microbalance beam. He also experimented with fused-on metal fibers. There is little information about the performance of these balances except that they possessed the extremely small capacity of about 1 mg. and were very fragile. Nevertheless the principle of the torsion fiber support of the beam is the basis of most contemporary precision microgravimetry. 

Epoxy polymers (including epoxy novolacs) have been designed to meet most of these requirements and are almost universally used in such encap-sulant applications. Epoxy polymers exhibit superior adhesion that in many cases eliminates the need for a barrier or junction coating. They have a low coefScient of thermal expansion low shrinkage and low injection velocity, which means that low transfer or injection pressures can be used. These polymers also possess excellent mechanical properties coupled with low moisture and gas permeability. Above all, they are cheap and readily available. Other transfer-molding materials used to a limited extent include silicones, phenolic materials, and even polyesters. Most molding formulations are highly filled (70-75%) with materials such as quartz, fused silica, short... 

It was assumed that the yield of OCM products could be enhanced by increasing the efficiency of CH3 recombination, which competes with reaction (35). Since the recombination of methyl radicals is a three-body process (see Section III.D), its efficiency can be increased by increasing total pressure, or by introducing an additional inert surface, which can play a role of third body. Indeed, it was demonstrated that the increase of inert gas (He or Ar) pressure at constant pressures of methane and oxygen leads to a substantial increase of OCM selectivity and yield (Sinev et al., 1996). Moreover, the addition of a 10-fold amount of various solid materials possessing a very low activity under the same conditions (quartz, fused MgO, Mg phosphate) to a relatively efficient OCM catalyst (Nd/MgO) led to a drastic increase (up to twofold) in the yield of OCM products (Sinev et al., 1997a, b). 

CuO / ZnO / A1203 Quartz fused silica Methanol steam reforming Bravo et al. [173]... 

SYNONYMS amorphous quartz, amorphous silica, cryptocrystalline quartz, fused quartz, fused silica, fuselex, microcrystalline quartz, quartz, glass, quartz sand, silicon dioxide, silicone dioxide, suprasil, vitreous silica. 

Silica, crystalline (quartz, fused amorphous silica, crislobolile, tridymite, tripoli [CAS 14464-46-1]) Inhalation of dusts causes silicosis, a progressive, fibrotic scarring of the lung. Individuals with silicosis are much more susceptible to tuberculosis. Some forms of crystalline silica are carcinogenic (lARC 2A). 0.1 mg/m (respirable dust quartz, fused silica. tripoll) 0.05 mg/m (respirable dust cristo-bollte, tridymite) 25 mg/m (cristobolite, tridymite) 50 mg/m (quartz, tripoll) Coloriess, odorless solid with a negligible vapor pressure. A component of many mineral dusts. 

Fiber, inorganic Fibers used in RPs, etc. include glass (different types), aluminum silicate, beryllium glass, carbon, ceramic, graphite, and quartz (fused silica). 

See Polypropylene Fused boric acid. See Boron oxide Fused quartz Fused silica. See Silica, fused Fusel oil. See Fusel oil refined Fusel oil refined... 

CAS 60676-86-0 EINECS/ELINCS 231-545-4 Synonyms Amorphous quartz Amorphous silica Cryptocrystalline quartz Fused quartz Fused silica... 

The electrodes for our work were prepared for us by Professor Christopher Chidsey and his coworkers at the Department of Chemistry, Stanford University. Quartz (fused silica) disks purchased from Heraeus-Amersil (Buford, GA) were cleaned for several minutes in a freshly prepared mixture of approximately 2 volumes H2SO4 and 1 volume of 30% by weight H2O2 in water at 80°C. The disks are then rinsed with copious... 

For determining the coefficient of linear expansion, it is a common practice to generate AL/Lq curves with and without the sample. The two cimves are subsequently subtracted to compensate for the expansion of the sample holder. For convenience, it is hest to use a standard reference material, eg, an isotropic metal such as alumimun or platinum (52), as the sample holder. In Figure 24, we see that, compared to other isotropic materials, quartz (fused silica) has a very low thermal expansion coefficient (0.6 x 10 /°C). It is also easily formed. If the upper... 

The use of films as electrodes makes possible numerous experiments that would be difficult or impractical to implement with conventional bulk electrodes. Conductive films employed as electrodes are usually classified as thin (thickness in the nanometer range) or thick (in the micrometer scale). There are numerous film fabrication methods available, depending on the material, and are included in thin-film and thick-film technologies. The most common materials for thin-film electrodes are gold and platinum metals and are deposited as a continuous film by sputtering or vacuum evaporation, commonly on an insulating substrate such as quartz, fused silica, glass, or polymeric materials. In many cases, adhesion is improved by a thin layer of an intermediate material as titanium or chromium. 

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