An electron transfer mechanism of O-4 formation

A resonating valence bond electron transfer mechanism of combining two O-2 molecules to form an O-4 molecule is presented. The predicted molecular states of the reaction path D-infinityh --> C-2v --> D-2h are supported by the present ab initio molecular orbital calculations. The CASPT2 BSSE calculations yield a stable diamagnetic D-2h O-4 molecule with a very weak chemical bond between the monomers, in good agreement with experiments. A low activation barrier energy of similar to26 cal/mol for the O-4 formation is found. (C) 2003 Elsevier Science B.V. All rights reserved.3704179578979

Quantum Monte Carlo study of the CO interaction with a dimer model surface for Cr(110)

The chemisorption of CO on a Cr( 110) surface is investigated using the quantum Monte Carlo method in the diffusion Monte Carlo (DMC) variant and a model Cr2CO cluster. The present results are consistent with the earlier ab initio HF study with this model that showed the tilted/ near-parallel orientation as energetically favoured over the perpendicular arrangement. The DMC energy difference between the two orientations is larger (1.9 eV) than that computed in the previous study. The distribution and reorganization of electrons during CO adsorption on the model surface are analysed using the topological electron localization function method that yields electron populations, charge transfer and clear insight on the chemical bonding that occurs with CO adsorption and dissociation on the model surface

SLC2A9 is a newly identified urate transporter influencing serum urate concentration, urate excretion and gout

Uric acid is the end product of purine metabolism in humans and great apes, which have lost hepatic uricase activity, leading to uniquely high serum uric acid concentrations (200?500 lM) compared with other mammals (3?120 lM)1. About 70% of daily urate disposal occurs via the kidneys, and in 5?25% of the human population, impaired renal excretion leads to hyperuricemia2. About 10% of people with hyperuricemia develop gout, an inflammatory arthritis that results from deposition of monosodium urate crystals in the joint. We have identified genetic variants within a transporter gene, SLC2A9, that explain 1.7?5.3% of the variance in serum uric acid concentrations, following a genome-wide association scan in a Croatian population sample. SLC2A9 variants were also associated with low fractional excretion of uric acid and/or gout in UK, Croatian and German population samples. SLC2A9 is a known fructose transporter3, and we now show that it has strong uric acid transport activity in Xenopus laevis oocytes