(2R)-Methyl[2-3H]malonyl-CoA was used as the substrate for methylmalonyl-CoA epimerase from Propionibacterium shermanii, under conditions where the (2S)-methylmalonyl-CoA product was removed enzymically as fast as it was formed, and the fate of the label was monitored at different extents of reaction. Very little, if any, tritium is found attached to the C-2 position in the (2S)-epimer product ...

Escherichia coli class Ia ribonucleotide reductase (RNR) converts ribonucleotides to deoxynucleotides. A diferric-tyrosyl radical (Y122•) in one subunit (β2) generates a transient thiyl radical in another subunit (α2) via long-range radical transport (RT) through aromatic amino acid residues (Y122 ⇆ [W48] ⇆ Y356 in β2 to Y731 ⇆ Y730 ⇆ C439 in α2). Equilibration of Y356•, Y731•, and Y730• was re...

For proton transfer reactions, the tunneling contributions to the rates are often much larger than thermally activated rates at temperatures of interest. A number of separable tunneling corrections have been proposed that capture the dependence of tunneling rates on barrier height and imaginary frequency size. However, the effects of reaction pathway curvature and barrier anharmonicity are more...

To probe the influence of structural variation within dibenzo-16crown-5-oxyacetic acids upon the selectivity of alkali metal cation separations by solvent extraction and liquid membrane transport processes, studies have now been conducted in homogeneous solution by NMR spectroscopy and titration calorimetry and in the solid state. Condensation polymerization of such proton-ionizable lariat ethe...

We show that the asymmetry in the fractional energy of charm versus an-ticharm jets produced in high energy diffractive photoproduction is sensitive to the interference of the Odderon (C = −) and Pomeron (C = +) exchange amplitudes in QCD. We predict the dynamical shape of the asymmetry in a simple model and estimate its magnitude to be of the order 15% using constraints from proton-proton vs. ...

the present paper explores the impact of an on-board hydrogen harvesting system (fuel reformer) on the overall efficiency of a fuel-cell powered vehicle. various methods of hydrogen production for automotive applications have been discussed first. as the hydrogen production is one of the major challenges for application of proton exchange membrane (pem) fuel cells, especially in vehicular indus...

This paper presents our research on silicon-based proton exchange membranes for siliconbased micro fuel cell applications. The porous silicon membranes with a thickness of 20-40 m were fabricated. And the porous silicon-based proton exchange membranes were formed by using the combination of the porous silicon membranes and Nafion solution. The proton conductivities of the porous silicon-based P...

Strangeness content is one of the most important questions in hadron structure because it sheds light on the role of the quark-anti quark sea in the ground state properties. One important tool is elastic parity-violating electron-proton scattering, which has been used to probe the the charge and magnetization distributions of the strange quark within the nucleon. At the tree level, the parity-v...

Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs) is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and ...