One-dimensional electrochemical cellular automaton (1D-ECA) has been extended so that effects of axial uniform flows toward the electrode can be simulated. The model is characterized by a sink connected to the terminating cell and a pair of asymmetric propagation probabilities that enables a drift with a constant velocity toward the electrode. The plots of the reciprocal stationary-state current and the reciprocal flow velocity yield a line, whose intercept corresponds to the current in the limit of fast mass transport.

View full abstract

Potentiometry utilizing redox reactions in a [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ redox-reagent solution has been considered as simple, highly sensitive, fast, and inexpensive method for evaluating total antioxidant activity (TAA) in various samples such as drinks, food, blood, etc. In this study, for the first time, the determination of TAA using potentiometric method has been applied to depression rating. For a depressed group of 94 persons and a normal group of 66 persons, beck depression inventory (BDI) score and TAA value were evaluated. From a comparison of BDI and TAA results, it is found that the TAA value is closely related to the BDI score and the value of TAA increases with decreasing BDI score. The plot of TAA vs. BDI exhibited a linear relationship with a negative correlation (Pearson’s coefficient r = −0.318, P < 0.01). This strongly suggests that the potentiometric method for TAA determination has a potential to be used as a clinical tool in depression.

View full abstract

The effects of Li utilization on the capacity and cycle stability of Li-O₂ batteries were studied by investigating the performance of cells incorporating varying ratio of Li metal to air electrode catalyst. The quantity of Li metal was found to affect the overall discharge capacity, such that the capacity decreased with decreasing amounts of Li in the anode. Although a capacity of only 354 mAh g⁻¹ (cathode) was obtained when the anode contained 0.9 mg Li, almost 100% of the Li in the cell was consumed during discharge, which corresponds to a capacity of 3932 mAh g⁻¹ (Li). The cycle stability of cells operating under high Li utilization conditions was, however, significantly reduced. Detailed analysis of the Li distribution in the cell suggests that decreased usage of Li within the first few cycles is the cause of the poor cycle stability. The results of this study suggest that low cycle stability in a Li-O₂ battery may be attributed to the formation of a surface passivation layer on the Li metal composed primarily of Li₂CO₃ and ROCO₂Li and generated by reaction with the electrolyte.

View full abstract

The influence of the sol-gel preparation condition of the composites of iron hydroxide with fibrous nano-carbon on their electrode properties has been investigated. The morphology, namely particle dispersion feature, of the Fe(OH)_x/nano-carbon composites and their electrode properties depend on the preparation conditions, such as titration rate and the kind of alkali. The specific capacity of the composite with carbon nanotube substrate is approximately twice by that with vapor-grown carbon fiber substrate, due to smaller size of the pitches within entangled tubes.

View full abstract