Oxygen composition, effect

Kohn, M.J., Schoeninger, M.J. and Valley, J.W. 1996 Herbivore tooth oxygen isotope compositions effects of diet and physiology. Geochimica et Cosmochimica Acta 60 3889-3896. 

Stamenkovic V, Schmidt TJ, Markovic NM, Ross PN Jr. 2002. Surface composition effects in electrocatalysis Kinetics of oxygen reaction on well defined PtsNi and PtsCo alloy surfaces. J Phys Chem B 106 11970-11979. 

Wood, peat, and coal, though so different in physical appearance, are nevertheless very closely allied in composition, all the three being chiefly composed of ligneous fibre, a compound of three simple elements— carbon, hydrogen, and oxygen. Physical effects have induced certain changes in some kinds of peat and... 

Catalyst Composition - Effect on Performance. Comparison of catalyst selectivities are best made at equal conversions. It was previously shown that selectivity of CO hydrogenation to oxygenates decreases with increasing conversion. For example, selectivity decreased linearly from 35% at 4% conversion to 20% at 18% conversion for Rh/Al203 catalysts at 250 C.(10)... 

Compositional effects in silicates. Compositional effects are also important in the oxygen isotope fractionation behavior of silicate minerals. The effects are complex, however, because of the large number of substitution mechanisms that operate in these minerals. Table 3 summarizes some of the major substitutions and their estimated effects on isotope fractionation (cf Kohn and Valley 1998a). Of the common substitution schemes, the plagioclase substitution has the largest isotopic effect. Experimental data (O Neil and Taylor 1967 Matsuhisa et al. 1979 Clayton et al. 1989) and theoretical calculations (Kieffer 1982) indicate a 1.05 to 1.2%o fractionation between albite and anorthite at 1000 K. This fractionation reflects the higher Si to Al ratio of albite, and the affinity of the Si-0 bond relative to the Al-0 bond for 0 (Taylor and Epstein 1962). In contrast to plagioclase, K Na substitution in the alkali feldspars, which does not affect the Si to Al ratio, has no measurable isotopic effect (Schwarcz 1966 O Neil and Taylor... 

The change in composition effected by the halides of phosphorus is the same as that described above under acids. For each hydroxyl group present there is a loss of one hydrogen and one oxygen, and a gain of one halogen atom. 

Superconductivity. The insulator-superconductor transition takes place near this composition probably as a result of the percolation of the hole doped clusters. At x = 6.342 small amounts of the material become superconducting (fig. 27b). Superconductivity under pressure A giant ATJAP effect has been measured at RT (sect. 5.4) indicating an increased compressibility at the T-0 transition due to the half-filled chains and strong oxygen-ordering effects. The effect disappears at LT where the mobility of oxygen freezes (fig. 58). 

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