On the parameters affecting the characteristics of the “wired” glucose oxidase anode

We recently described a redox polymer with an $\mathrm{Os}(N,N^{\prime }\text{-}\mathrm{dialkylated}\mathrm{biimidazole}{)}_3^{2+/3+}$ redox center with a redox potential of ?195 mV vs. Ag|AgCl, 800 mV reducing relative to its 2,2′-bipyridine analog. The tethering of the centers to a poly(4-vinylpyridine) backbone through a 13 atom long spacer arm, provided for an apparent electron diffusion coefficient as large as 5 × 8.10^?6 cm² s^?1. The glucose electro-oxidation catalyst formed by “wiring” glucose oxidase with this polymer allowed the electro-oxidation of glucose already at ?360 mV vs. Ag|AgCl at pH 7.2, near the reversible potential of glucose oxidase, at a current density of 1.3 mA cm^?2 in the presence of 32 mM glucose concentration. Here we consider the parameters affecting the characteristics of this anode, compare the characteristics with those of an anode made with a short-tethered “wire” and describe the optimization of the composition of the “wired” glucose oxidase.     

On the impedance of porous electrodes – double-layer charging and charge transfer on an inhomogeneous inside electrode surface

A model of the impedance of porous electrodes was derived. The model generalized the de Levie model in so far that an inhomogeneous inside electrode surface is assumed. Then the charge transfer resistance and the double-layer capacity were assumed to be distributed. The width of the distribution is characterized by a distribution parameter. The inhomogeneities led to characteristic deviations of the Nyquist impedance plots compared to those for homogeneous inside electrode surfaces: the slope angle of the straight line for higher frequencies was less than π/4, the slope angle of π/2 of the straight line obtained for double-layer charging only and lower frequencies decreased and the semicircle behaviour obtained for double-layer charging and a Faradaic reaction in parallel were replaced by a depressed semicircle. The model allows the determination of the following parameters: the total effective double-layer capacity, the total effective charge transfer resistance, the distribution parameter and the total resistance of the electrolyte inside the pores. The impedance of porous zinc electrodes in weakly alkaline electrolyte can be theoretically well described with the new model. A scanning force microscopy 2-D-image of the morphology of the zinc electrode was performed and discussed.     

Right maintenance and self-discipline of practicing dentist On the liability in medical damage of the tortuous liability(Ⅲ): medical damage in medical dispute and identification of its liability

上一讲主要介绍了医疗争议中的侵权行为构成以及侵权责任的认定,本讲继续就医疗争议中的医疗损害及其责任认定做出解读.本讲继续附以案例报告.