INDEX with oxide fibers

Most fibers have a core which consists of silica doped with oxides of germanium or phosphorus to raise the refractive index. The cladding usually consists of pure, undoped silica... 

Highly pure lanthanum oxide is used to make optical glass of high refractive index for camera lenses. It also is used to make glass fibers. The oxide also is used to improve thermal and electrical properties of barium and strontium titanates. Other applications are in glass polishes carbon arc electrodes fluorescent type phosphors and as a diluent for nuclear fuels. In such apph-cations, lanthinum oxide is usually combined with other rare earth oxides. 

For the light guiding effect of optical fibers it is important to have a core with a refractive index somewhat larger than that of the airrounding cladding. Therefore the core normally consists of silica doped with other oxides to increase the refractive index. In the following we therefore discuss the simultaneous deposition of silica and germania in the silica tube. 

Oil (Aa 4-38) determines oil content in a dried sample of oil-bearing material by extraction with petroleum ether. This method is specific for cottonseed, which first must be fumed with hydrochloric acid to prevent oil adsorption to the fiber. Additional methods exist for other oilseeds. Oxygen Stability Index (OSI) (Cd 12b-92) measures the oxidation induction period of fat sample (essentially the time for a sample to exhaust its antioxidant properties) under conditions of the test. 

Oxidative degradation appears to be the main mechanism governing humification. In determining the degree of decomposition or humification of peat materials the estimation of total fiber content correlates well with relative biodegradability and is a more reliable method than either the pyrophosphate index or bulk density values. 

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