Isotopic analyses oxygen isotopes

In this equation the red O signifies oxygen enriched in Its mass 18 isotope analysis of isotopic enrichment was performed by mass spectrometry... 

Marino, B.D. and DeNiro, M.J. 1987 Isotopic analysis of archaeobotanicals to reconstruct past climates Effects of activities associated with food preparation on carbon, hydrogen and oxygen isotope ratios of plant cellulose. Journal of Archaeological Science 14 537-548. 

Two alternate methods have recently been developed and both are used in the present study. A laser probe analytical method provided the majority of the oxygen isotope data (see Kohn et al. 1996 for details on testing and developing the method). Laser probes were originally developed for the stable isotope analysis of silicates, oxides, and sulfides in ciystalline rocks (Crowe... 

This equation predicts a value of 26.8%ofor the zebra at Turkana assuming an average value of 6%o for Lake Turkana water. This predicted value is l%o less than the actual value of 27.8%o. Given the variation in methods of sample preparation and analysis, variation between bone and tooth enamel (Stuart-Williams and Schwarcz 1997), and uncertainty in surface water oxygen isotopic composition, these values are extraordinarily close. Alternatively, if the equation is solved for using the actual value of the Turkana zebra. 

Cerling, T. and Sharp, Z. 1996 Stable carbon and oxygen isotope analysis of fossil tooth enamel... 

Clayton, RN. and Mayeda, T.K. 1963 The use ofbromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochimica et CosmochimicaActa 27 43-52. 

O Neil, J.R., Roe, L.J., Reinhard, E. and Blake, R.E. 1994 A rapid and precise method of oxygen isotope analysis of biogenic phosphate. IsraelJournal of Earth Sciences 42 203-212. 

Tudge, A.P. 1960 A method of analysis of oxygen isotopes in orthophosphate-its use in the measurement of paleotemperatures. Geochimica et Cosmochimica Acta 18 81-93. 

Schwarcz, H.P., Gibbs, L. and Knyf, M. 1991 Oxygen isotopic analysis as an indicator of place of origin. In Pfeiffer, S. and Williamson, R.E, eds.. Snake Hill An Investigation of a Military Cemetery from the War of 1812. Toronto, Dundurn Press 263-268. 

Craig H (1957) Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide. Geochim Cosmochim Acta 12 133-149. 

Saurer M, I Robertson, R Siegwolf, M Leuenberger (1998) Oxygen isotope analysis of cellulose an interlaboratory comparison. Anal Chem 70 2074-2080. 

After approximately 3 min on stream in the isotopic mixture of CH4/02/C 02/He, a steady-state value in the rate of formation is obtained (Fig. 3). This value is used to estimate the relative contribution of the CO2-reforming route to the overall production of CO (direct + indirect routes). Proper analysis of this result, taking into consideration scrambling of isotopic oxygen Figure 3. Transient isotopic labelling experiment atoms between the CO2 and O2 molecules... 

The Special Issue of Resource Geology on the Hishikari deposits (Shikazono et al., 1993) includes various aspects of the Hishikari deposits (oxygen isotopes of gangue minerals, hydrothermal alteration, precipitation sequence, fluid inclusions, vertical electric profiling and electric sounding surveys, structural geological analysis, opaque minerals. 

Hayashi, K., Maruyama, T. and Satoh, H. (2000b) Precipitation of gold in a low-sulfidation epithermal gold deposit Insights from a submillimeter scale oxygen isotope analysis of vein quartz. Econ. Geol, 96, 211-216. 

When a sample of the same Kevlar-29 fabric was identically treated in l 02-atmosphere except in the absence of photolysis (in the dark) for 24 hours, the results of C02 evolved at 25° and 196°C from the GC-analysis were the same as the samples under photolysis (e.g., Table I). However, the gross difference was in the analyses of the GC-mass spectroscopic data, where no oxygen-18-labelled C02 isotopes evolved (i.e., there was no C02 or 48co2 above the natural background levels). ... 

Shackleton, N. J. (1973), Oxygen isotope analysis as a means of determining season of occupation of prehistoric hidden sights, Archaeometry 15,133-141. 

Reactions of eh with H and OH were once considered diffusion-controlled see, however, Elliot et al. (1990). The rate constants, 2.5—3.0 x 1010 M-1s 1 (see Table 6.6), are high. In both cases, a vacancy exists in the partially filled orbitals of the reactants into which the electron can jump. Thus, hydrogen formation by the reaction eh + H may be visualized in two steps (Hart and Anbar, 1970) eh + H—H, followed by H + H20— OH" This reaction has no isotope effect, which is consistent with the proposed mechanism. The rate of reaction with OH is obtained from the eh decay curve at pH 10.5 in the absence of dissolved hydrogen or oxygen, where computer analysis is required to take into account some residual reactions. At higher pH (>13), OH exists as O- and the rate of eh + O—"02 has been measured as 2.2 x 1010 M-1s-1. 

TO test the reactor and analysis system, pulses of methanol, singly, and completely deuterated methanol were led over the commercial Pe (MoO.) VtoO, catalyst and the two separate phases, m this way, we can check-3if a kinetic isotope takes place on the separate phases, and the measurements can be extended to a larger temperature range more readily than under steady state conditions. The pulses contained about 12% methanol in argon and 10% oxygen. 

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