Nature and coordination geometry of geologically relevant aqueous Uranium(VI) complexes up to 400 ºC: A review and new data.

The structure of the uranyl aqua ion (UO) and a number of its inorganic complexes (specifically, UOCl, UOCl, UOSO, [Formula: see text] , [Formula: see text] and UOOH) have been characterised using X-Ray absorption spectroscopy/extended X-Ray absorption fine structure (XAS/EXAFS) at temperatures ranging from 25 to 326 ºC. Results of ab initio molecular dynamics (MD) calculations are also reported for uranyl in chloride and sulfate-bearing fluids from 25 to 400 ºC and 600 bar to 20 kilobar (kb). These results are reported alongside a comprehensive review of prior structural characterisation work with particular focus given to EXAFS works to provide a consistent and up-to-date view of the structure of these complexes under conditions relevant to U mobility in ore-forming systems and around high-grade nuclear waste repositories.

Uranium carbonate complexes demonstrate drastic decrease in stability at elevated temperatures.

Quantitative understanding of uranium transport by high temperature fluids is crucial for confident assessment of its migration in a number of natural and artificially induced contexts, such as hydrothermal uranium ore deposits and nuclear waste stored in geological repositories. An additional recent and atypical context would be the seawater inundated fuel of the Fukushima Daiichi Nuclear Power Plant. Given its wide applicability, understanding uranium transport will be useful regardless of whether nuclear power finds increased or decreased adoption in the future.

Application of the photon average trajectories method to real-time reconstruction of tissue inhomogeneities in diffuse optical tomography of strongly scattering media.

The possibility of application of the photon average trajectories (PAT) method to real-time reconstruction of tissue inhomogeneities in diffuse optical tomography of strongly scattering media has been substantiated. By this method, the inverse problem is reduced to solution of the integral equation with integration along a conditional PAT. Such an approach allows the standard fast algebraic algorithms commonly used in projection computed tomography to be applied to diffuse optical image reconstruction.