A voltammetric study on the transfer of polyoxometalate anions at the oil½water interface highlighted the utmost importance of short-range ion–solvent interactions in the transfer or resolvation energy. Based on these findings the author proposed a non-Bornian solvation model, in which the Born-type long-range electrostatic interaction was daringly ignored and the ion solvation energy (scaled by the surface area) was simply expressed as a quadratic function of the ion's surface field strength. This model was successfully used to calculate the hydration energy and the transfer energy at the oil½water interface, for a variety of inorganic and organic ions. In the analysis for an organic ion, the local surface field strengths on the minute surfaces of the ion were evaluated through DFT calculation. A few applications of the present solvation model are also described, featuring its higher usefulness.

To reduce the threat and increase usefulness of microorganisms, it is necessary to have a better understanding of their biological functions. It is important to evaluate the bacterial activity in real time for various purposes such as hygiene management, development of antibacterial agents, and effective utilization of bacterial resources. This requires a quantitative assessment of metabolic processes such as growth and respiration. Here, we would like to introduce the development of electrochemical methods for assessing bacterial activity.

The pure gold dissolution has been explored in (dilute) chloric, bromic, or iodic acid (HXO₃, X = Cl, Br, I) aqueous solution containing abundant halide ions at 60°C. It has been found that mixtures between sodium chlorate and HCl (NaClO₃ + HCl ⇆ HClO₃ + NaCl) in 20 mL are effective media for the dissolution of pure gold-wire (99.95 %, 0.25 mm diameter, ca. 20 mg). The gold-wire dissolution is much more enhanced by HBr than HCl in NaClO₃ solution. At 0.50 mol dm^-3 NaClO₃, for instance, log (k/s^-1) values are -5.11 and 3.40 (ca. 50-fold increase) for 1.0 mol dm^-3 HCl and HBr, respectively, where first-order dissolution rate constants (k/s^-1) have been evaluated by the changes in the mass of gold-wire. In HClO₃ solution containing abundant halide ions (X^- = Cl^-, Br^-), the Au metal should be oxidized mainly by X₂ to be AuX₄^-, where X₂ is produced by the oxidizing power from HClO₃, just as dilute HNO₃ (< 2 mol dm^-3) containing abundant NaCl. In NaBrO₃ solution, however, HBr does not acquire any superiority to HCl in the gold dissolution. In NaIO₃ solution, the effect of HX at the lower concentrations (< 0.03 mol dm^-3) of NaIO₃ increases in the order of HCl < HBr < HI. The gold dissolution in hypochlorous acid (HClO) containing halide ions has been also examined as the reference. A new diagram has been proposed in order to verify that even the conjugate anion (ClO₃^- or NO₃^-) from a strong acid (HClO₃ or HNO₃) is subject to be protonated in the “aqueous solution” modified by electrolytes of very high concentrations (> ~5 mol dm^-3). Additionally, stainless-steel corrosion has been examined in NaClO₃ solution containing aboudant HCl.

The open circuit potential (zero current potential) includes not only “equilibrium potential” determined by a single charge-transfer reaction but also “mixed potential” determined by two or more charge-transfer reactions. The mixed potential is often measured as corrosion potential or the ion-selective electrode potential responsive to interference ions. This paper describes a method for calculating the mixed potential, limited to reversible electrochemical reactions.