Electron transport system activity, calculating

Various methods have been used to estimate water-column denitrification rates including stoichiometric relationships, measurements of the enzymatic activity of the electron transport system (ETS), and N03 incubation experiments. In combination with residence times or mass transport calculations these measurements yield areal denitrification rates. 

For good intramolecular electron transport to be achieved, the molecule must be as planar as possible. The more extended the delocalized 7c-electron system, the better will be the conductivity. The specific conductivity thus increases sharply in the series coronene, ovalene, circumanthracene, graphite (Table 14-3). The activation energy El of the electronic conduction, which can be calculated using... 

The performance of enzyme electrodes— particularly those with three-dimensional porous architecture—is affected by both enzyme kinetics and mass transfer to, and through, the electrode architecture. Understanding these mechanisms requires an approach that models the reactant concentration at the enzyme surface based on bulk concentrations, which is measured in situ by online spectrophotometric detection or ex situ by liquid chromatography. In this approach, the mass transfer characteristics of the electrodes are estimated by comparison of experimental data with model predictions of system performance in the presence of continuous flow. Thereafter, a combined mass transfer parameter can be calculated and enzyme kinetics can be evaluated. The primary advantages of this approach are to rapidly screen immobilization protocols and to provide some insight into mass transport of reactants, metabolic by-products, and electrons. Specifically, it is possible to estimate the actual Umax of tho electrode, and hence quantify the amount of active enzyme available for bioelectrocatalysis. 

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