Spin and orbital magnetic moments of UTe induced by the external magnetic field.

Correlated band theory implemented as a combination of the relativistic density functional theory with exact diagonalization [DFT+U(ED)] of the Anderson impurity term with Coulomb repulsion U in the 5f shell is applied to the magnetic field polarized state of [Formula: see text]. We demonstrate that the DFT+U(ED) approach provides a good agreement with very recent x-ray absorbtion near edge structure (XANES) and x-ray magnetic circular dichroism (XMCD) experiments. The branching ratio for the [Formula: see text] edge transitions of uranium, and the valence spin-orbit interaction per hole were evaluated in a perfect agreement with the XANES.

Deconvolving microbial and environmental controls on marine sedimentary pyrite sulfur isotope ratios.

Reconstructions of past environmental conditions and biological activity are often based on bulk stable isotope proxies, which are inherently open to multiple interpretations. This is particularly true of the sulfur isotopic composition of sedimentary pyrite (δS), which is used to reconstruct ocean-atmosphere oxidation state and track the evolution of several microbial metabolic pathways. We present a microanalytical approach to deconvolving the multiple signals that influence δS, yielding both the unambiguous determination of microbial isotopic fractionation (ε) and new information about depositional conditions.

Sedimentary parameters control the sulfur isotope composition of marine pyrite.

Reconstructions of coupled carbon, oxygen, and sulfur cycles rely heavily on sedimentary pyrite sulfur isotope compositions (δS). With a model of sediment diagenesis, paired with global datasets of sedimentary parameters, we show that the wide range of δS (~100 per mil) in modern marine sediments arises from geographic patterns in the relative rates of diffusion, burial, and microbial reduction of sulfate. By contrast, the microbial sulfur isotope fractionation remains large and relatively uniform.

The geologic history of primary productivity.

The rate of primary productivity is a keystone variable in driving biogeochemical cycles today and has been throughout Earth's past. For example, it plays a critical role in determining nutrient stoichiometry in the oceans, the amount of global biomass, and the composition of Earth's atmosphere. Modern estimates suggest that terrestrial and marine realms contribute near-equal amounts to global gross primary productivity (GPP).

Nuclear spin effects in biological processes.

Traditionally, nuclear spin is not considered to affect biological processes. Recently, this has changed as isotopic fractionation that deviates from classical mass dependence was reported both in vitro and in vivo. In these cases, the isotopic effect correlates with the nuclear magnetic spin.