Changes in X-nuclei screening and scalar spin-spin X H ( D ) coupling constants induced by the H D substitutions in isotopom ers [XH 4_„D„] (X = N , A l, Ga) have been determined by 1415N , 27A l, 69 71Ga NM R. Isotopic chemical shifts of nuclei 51V, 53Cr, "Tc induced by the 160 —lsO substitution have been measured for tetra-oxo com plexes [V 0 4]3~, [C r04]2~, and [T c 0 4]~. The deuterium-ind...

RATIONALE Isotope ratio mass spectrometry (IRMS) is used extensively to reconstruct general attributes of prehistoric and modern diets in both humans and animals. In order to apply these methods to the accurate determination of specific intakes of foods/nutrients of interest, the isotopic signature of individually consumed foods must be constrained. For example, 86% of the calories consumed in ...

Carbon isotopic studies from marine organic matter of the Permian-Triassic Maitai Group, New Zealand, reveal a significant 5Corg shift toward more negative values within the Little Ben Sandstone Formation. These isotopic data chemostratigraphically define the previously debated position of the Permian-Triassic boundary in the Maitai Group. The Permian-Triassic record of the Maitai Group is also...

We describe the isotopic exchange of lactate and pyruvate after arm vein infusion of [3-(13)C]lactate in men during rest and exercise. We tested the hypothesis that working muscle (limb net lactate and pyruvate exchange) is the source of the elevated systemic lactate-to-pyruvate concentration ratio (L/P) during exercise. We also hypothesized that the isotopic equilibration between lactate and p...

Archean supracrustal sequences of pelitic, quartzitic, calcareous and mafic compositions in the central Laramie Mountains, Wyoming, have been affected by two metamorphic events: a 1.78 Ga amphibolitegrade regional metamorphism, and a 1.43 Ga contact metamorphism resulting from the intrusion of the Laramie Anorthosite Complex (LAC). Rb–Sr whole-rock isotopic data from both outside and within the...

Most estimates of planetary core formation timescales using hafnium–tungsten (Hf–W) isotopes employ analytical expressions assuming either continuous planetary growth or instantaneous core formation. In contrast, dynamical modelling of planetary accretion suggests that the final stage of terrestrial planet formation is punctuated by multiple large and stochastic impacts. Such giant impacts have...

The killing of large numbers of migratory bats at wind turbines is a pressing conservation problem. Even though avoidance and mitigation measures could benefit from a better knowledge of the species' migratory habits, we lack basic information about what habitats and corridors bats use during migration. We studied the isotopic niche dimensions of three bat species that are frequently killed at ...

a r t i c l e i n f o a b s t r a c t The isotopic composition of precipitation (δ P) is one of the most widely used and informative terrestrial paleoclimate proxies. δ P integrates a series of hydrological processes; therefore, any interpretation of paleohydrology using δ P requires a thorough understanding and quantification of the full hydrological cycle. In this paper, we use modern data to...