Andrew Webber

Conductivity and Viscosity of Solutions of LiCF3 SO 3, Li ( CF 3 SO 2 ) 2 N , and Their Mixtures

The high level of charge delocalization of the anion reduces ion pairing in nonaqueous electrolytes. This overrides the higher viscosity of the imide‐containing solutions making the electrolytes much more conductive than those containing , especially in low dielectric ether‐based solvent systems commonly used in secondary lithium batteries. In more viscous solvent systems (1:1 propylene carbonate: 1,2‐dimethoxyethane) or at low temperatures, the imide affords less of an advantage in conductivity due to the more important role of viscosity. The cyclic imide gives more viscous and less conductive solutions than does . The degree of dissociation in 1:1 PC:DME appears to be

Cathodic reduction of nicotinamide adenine dinucleotide and other adenine-containing compounds in acidic media

Abstract Both nicotinamide adenine dinucleotide (NAD+) and acid-hydrated NADH, as well as adenine, adenosine, adenosine mono-, di-, and tri-phosphate and adenosine diphosphoribose, undergo four-electron reductions of the protonated adenine ring in acidic media. The values of αna (transfer coefficient times the number of electrons involved in the rate-determining step), n (total number of electron transferred), and p (number of protons involved in the rate-determining step) agree well with values previously reported for adenine. Cathodic stripping voltammetry of an adsorbed film can be applied to these compounds. Rapid scan rates are required to eliminate the slow desorption step at −1.1 V vs. SCE for some of these compounds. Hydration of the nicotinamide ring of NADH appears to inhibit this desorption step, but does not appear to be related directly to the electroactivity of the hydration product.

Electrochemical reduction and determination of cimetidine at nanomolar to micromolar levels of concentration

Abstract The electrochemical reduction of cimetidine, an H 2 -antagonist of histamine used in the treatment of duodenal and gastric ulcers, has been examined by using a variety of electrochemical techniques. Reduction in 0.1. M HCl occurs at −0.8 to −1.1 V vs. SCE depending on the experimental conditions. Square-wave and cyclic voltammetry were found to be the best techniques for the determination of cimetidine whereas sampled-d.c., normal pulse, and differential pulse polarography were not useful. The detection limit for the determination depends on the condition employed but can be as low as 1 ng ml −1 (4 nM). A linear calibration plot is obtained up to 2 μg ml −1 and calibration curves can be used at higher concentrations. The high sensitivity is due to reactant adsorption. The electrode process appears to involve a 4-electron reduction of the cyano group in cimetidine. The major metabolites of cimetidine can also be determined by this method.

The electrochemical reduction and determination of reduced nicotinamide adenine dinucleotide in acidic media

Abstract The apparent reduction of reduced nicotinamide adenine dinucleotide (NADH) in acidic media at a static mercury drop electrode was investigated. A simple, quick pretreatment procedure was developed to convert the NADH to its acid-hydrated form. This adsorbs on the mercury surface during a film deposition time and the film is then reduced. The adsorption is diffusion-controlled and hence the peak currents for square-wave and linear-scan voltammetry are proportional to Ct 1/2 p Af and Ct 1/2 p Av , respectively, where t p is the effective film deposition time, C the concentration of NADH, A the electrode area, f the square-wave frequency, and ν the linear scan rate. Several electrochemical techniques were compared for the determination of NADH; the method of choice is square-wave voltammetry, although staircase or linear scan voltammetry can also be used. The detection limit is less than 7 nM, and the range of linear response covers 2–3 orders of magnitude of NADH concentration.

Development and Characterization of a Thick-Film Printed Zinc-Alkaline Battery

bEnergizer Battery Company, Cleveland, Ohio 44145, USA Application of thick-film printing technology to the fabrication of a zinc-alkaline battery was carried out in this study. Electrode inks were formulated using active materials in powdered form, poly~ethene oxide! as binder, graphite as conductor, and water as solvent. Zinc-containing anodes and manganese dioxide cathodes were thick-film printed onto silver current collectors and assembled into cells using separator paper and potassium hydroxide electrolyte. The cells were cathode limited and had a theoretical capacity between 3 and 4 mAh. The highest discharge efficiency achieved was 97% of the theoretical capacity of the cathode at a discharge rate of 1 mA/cm 2 . Characterization of the electrochemical properties of the cell was carried out and assessed.