Radical-induced degradation of proton exchange membranes limits the durability proton-exchange membrane fuel cells. Cerium is widely used as a radical scavenger, but migration cerium ions to the...

Aldehyde condensation is a reaction step in the oxidization of lubricant base stock into high-molecular-weight products, forming sludge and paint film, which lead to failure lubricating oil. Calculations on basis density functional theory (DFT) were employed investigate mechanism acid-catalyzed aldol stock. Carbonyl compounds could be converted their resonant enol structures. However, activatio...

This transformation is intramolecular and would involve no exchange between the migratory hydrogen and hydrogen in the aqueous solvent. (2) The hydrogen may migrate as a proton (Fig. l), in which case exchange with the solvent would occur. In order to distinguish between these alternatives the conversion of fructose-6-phosphate (F-6-P) into glucose-6phosphate (G-6-P)) catalyzed by phosphoglucos...

Holotryptophanase in the presence of K+ undergoes a pHdependent change (pK 7.2) from a protonated, enzymatically inactive form (EH), X,,, 420 rnp, to a deprotonated, active form (S), X,,, 337 mp. Only the inactive form appears when K+, which is required for activity, is replaced by Na+ or imidazole. Both forms of the enzyme are completely inactivated by borohydride reduction, indicating that ea...

The DPNase from pig brain has been found to catalyze an exchange reaction between isonicotinic acid hydraaide and DPN to form the isonicotinic acid hydraeide analogue of DPN (l).’ In a preliminary paper (2) we have reported that the pig brain DPNase catalyzed the formation of the 3-acetylpyridine analogue of DPN (APDPN) according to the following equation, in which R represents the adenosine di...

Gas-phase dissociations were investigated for several peptide ions containing the Gly-Leu* N-terminal motif where Leu* was a modified norleucine residue containing the photolabile diazirine ring. Collisional activation of gas-phase peptide cations resulted in facile N₂ elimination that competed with backbone dissociations. A free lysine ammonium group can act as a Brønsted acid to facilitate N₂...

In this work membrane (proton exchange membrane) by using the blend polymers (polyethersulfone (PES), Expandable polystyrene (EPS), polyvenylidinefluride polymer (PVDF)) were prepared. This was modified adding organic sulfonic acid to solution precasting process, and sulfonated dipping it in diluted sulfuric (H2SO460%) post casting process. The sulfonation confirmed via FTIR spectra. characteri...