A derivation of the classical jump rate I' for tracer diffusion aimed at a clear expression for the mass dependence of the frequency factor v is presented. The derivation is effected without using the usual collective normal coordinates which usually combine the masses in a complicated way. v depends explicitly on the mass of the surrounding host atoms (as well as on the tracer-atom mass) if th...

Kinetic isotope effects related to the breaking of chemical bonds drive sulfur isotope fractionation during dissimilatory sulfate reduction (DSR), whereas oxygen isotope fractionation duringDSR is dominated by exchange between intercellular sulfur intermediates and water. We use a simplified biochemical model for DSR to explore how a kinetic oxygen isotope effect may be expressed. We then explo...

Orotidine-5'-monophosphate decarboxylase (OMP decarboxylase, ODCase) catalyzes the decarboxylation of orotidine-5'-monophosphate (OMP) to uridine-5'-monophosphate (UMP). Despite extensive enzymological, structural, and computational studies, the mechanism of ODCase remains incompletely characterized. Herein, carbon kinetic isotope effects were measured for both the natural abundance substrate a...

New rock magnetic results (thermal fluctuation tomography, high-resolution first-order reversal curves and low temperature measurements) for samples from the Paleocene-Eocene thermal maximum and carbon isotope excursion in cored sections at Ancora and Wilson Lake on the Atlantic Coastal Plain of New Jersey indicate the presence of predominantly isolated, near-equidimensional single-domain magne...

A growing body of evidence has indicated that energy metabolism impairment may be involved in pathophysiology of some neuropsychiatric disorders. In this study, we evaluated the effect of acute and chronic administration of fluoxetine, olanzapine and the combination of fluoxetine/olanzapine on citrate synthase activity in brain of rats. For acute treatment, Wistar rats received one single injec...

[1] The toxicity of mercury’s methylated species and its biomagnification in aquatic food chains and global dispersion by the atmosphere are the cause of worldwide health problems. Recent reports have observed natural mass-dependent fractionation in mercury isotopes, and recent theoretical work has demonstrated that isotopic separation in mercury is due primarily to nuclear field shifts (nuclea...

The level of co-extracted matrix in wheat and oat extracts obtained by the QuEChERS method (EN 15662) is high and the occurrence of free fatty acids generates a major matrix peak in TIC chromatograms (rt. 13-22min). Matrix can compromise the analytical performance in pesticide analysis using GC-MS/MS. In order to reduce the amount and the effects of matrix we tested the effect of using six diff...