Vital effects

Berger (1991) summarized the importance of the so-called vital effect on a broad range of organisms (see Fig. 3.42). For oxygen isotopes, most organisms precipitate CaCOs close to equilibrium if disequilibrium prevails, the isotopic difference from equilibrium is rather small (Fig. 3.42). For carbon, disequilibrium is the rule, with... 

The type and engineering quality of the measuring device actually used may have vital effect on the results. In the case of automatic feed of indenter loading, the measuring accuracy is higher than for hand-operated feed (Fig. 6.5.1). As a result, for hardness testers with hand-operated loading, it is advisable to take more measurements. 

In order to get an approximate estimate of let us make the simplifying assumption that the electronegativities of all the atoms in the transition state are equal. (This can be shown to have no vital effect on the argument introduction of differences in electronegativity by the perturbation methods outlined... 

From a general survey of the literature it appears that the most common causes of poor yields in the Friedel-Crafts cyclization of acid chlorides are (a) reaction conditions which are too drastic, and (b) reagents of inadequate purity. The optimum conditions are those which are mild but still sufficient to complete cyclization. An apparent necessity for heating the reaction mixture in order to induce cyclization may be due, in part, to insufficient purity of reagents. The vital effect of the presence of impurities on the Friedel-Crafts reaction is fairly well known,62 63 but the advantage of mild conditions has not been generally appreciated. 

This Waterloo was unfortunate for the author considers the boron method to be basically sound and potentially extremely powerful. The answer to the benthic enigma may lie in species-to-species differences in the boron isotope vital effect for benthic foraminifera. The measurement method use by Sanyal et al. (1996) required a large number of benthic shells in order to get enough boron to analyze. This created a problem because, as benthics are rare among foraminifera shells, mixed benthics rather than a single species were analyzed. If the boron isotope pH proxy is to... 

Potential analytical bias, vital effects, and calibration issues all complicate interpretation of the records shown in Figure 10. Measured benthic foraminiferal Mg/Ca ratios in site 747 (Billups and Schrag, 2002) are in general higher than in coeval samples from the composite record of... 

Grossman E. L. (1987) Stable isotopes in modem benthic foraminifera a study of vital effect. J. Foraminiferal Res. 17(1), 48-61. 

Spero H., Lerche I., Williams D.F. (1991) Opening the carbon isotopes vital effect black box, 2. Quantitative model for interpreting foraminiferal carbon isotope data. Paleoceanogr. 6, 639-55. 

Vital effects and beyond a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera... 

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