a sensitive and selective kinetic-spectrophotometric method was developed for the determination of trace amounts of uric acid. the method is based on the inhibitory effect of uric acid on the oxidation of janus green by bromate in the presence of sulfuric acid. the reaction was followed spectrophotometrically by measuring the absorbance at 518 nm using the fixed-time method. under optimum exper...

Poly(acrylic acid) (PAA) chains exhibit conformational change in response to pH, whereas bromate-sulfite-ferrocyanide (BSF) solution shows pH oscillation between 3.2 and 6.6. By use of quartz crystal microbalance with dissipation (QCM-D), we have investigated the pH induced conformational change of PAA brushes under a continuous flow of BSF solution in real time. The changes in frequency and di...

A novel molybdenum-free nitrate reductase was isolated from the obligate chemolithoautotrophic and facultative anaerobic, (halo)alkaliphilic sulphur-oxidizing bacterium Thioalkalivibrio nitratireducens strain ALEN 2. The enzyme was found to contain vanadium and haem c as cofactors. Its native molecular mass was determined as 195 kDa, and the enzyme consists of four identical subunits with appar...

tween steady and oscillatory states, and marked sensitivity to stirring rate. Thiocyanate shows none of these features. A mechanistic explanation of the chlorite-bromide oscillations seems within reach given the reactions's similarity to the chlorite-iodide reaction and the success of numerical simulations' ' , 1 2 of batch behavior in the chlorite-bromide system. In contrast, very little is kn...

We develop a general model and the associated numerical algorithm to compute the swelling dynamics of chemo-responsive polyelectrolyte gels immersed in a reactive ionic solution kept at a non equilibrium stationary state by a permanent feed of fresh reactants. Using an autocatalytic bistable but nonoscillatory reaction, namely, the bromate-sulfite reaction, we predict that a piece of hydrogel t...