Stable sulfur and oxygen isotope fractionation of anoxic sulfide oxidation by two different enzymatic pathways.

The microbial oxidation of sulfide is a key reaction of the microbial sulfur cycle, recycling sulfur in its most reduced valence state back to more oxidized forms usable as electron acceptors. Under anoxic conditions, nitrate is a preferential electron acceptor for this process. Two enzymatic pathways have been proposed for sulfide oxidation under nitrate reducing conditions, the sulfide:quinone oxidoreductase (SQR) pathway and the Sox (sulfur oxidation) system.

Disproportionation of elemental sulfur by haloalkaliphilic bacteria from soda lakes.

Microbial disproportionation of elemental sulfur to sulfide and sulfate is a poorly characterized part of the anoxic sulfur cycle. So far, only a few bacterial strains have been described that can couple this reaction to cell growth. Continuous removal of the produced sulfide, for instance by oxidation and/or precipitation with metal ions such as iron, is essential to keep the reaction exergonic.

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers.

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of (13)C, which complicates the evaluation of degradation.

Analysis of the rigid and deformable component of setup inaccuracies on portal images in head and neck radiotherapy.

The issue of setup errors consisting of translation, rotation and deformation components in head and neck radiotherapy is addressed with a piecewise registration of small independent regions on a portal image to their reference position. These rectangular regions are termed featurelets as they contain relevant anatomical features. The resulting displacement vectors of each featurelet reflect both the center-of-mass (COM), i.