Iron based oxides were synthesized by precipitation route from a ferric nitrate aqueous solution at low temperature followed by heat treatment of the precipitate. The samples thus obtained were characterized by X-ray powder diffraction, transmission electron microscopy, surface area measurement, and electrochemical investigation in a LiClO4-propylene carbonate solution. Nanocirystalline α-Fe2O3 powders, which were obtained by heat treatment at 200°C, demonstrated high reversible capacity of >200 mAh g−1 and good cyclability as a positive electrode of Li batteries. It was likely that the discharge-recharge of the nanocrystalline α-Fe2O3 was due to a topochemical reaction accompanied with lithium insertion/extraction.
This paper describes the phosphorus distribution and content in the electroless nickel films at both the initial stages and following steady state of deposition conditions. From the results of EPMA, GDOES and AES measurements, it was found that phosphorus contents in the deposited films at the initial stages indicate higher values than the following steady state deposition. The highest phosphorus content in the films was obtained from the citric acid bath among the tested complexing agents. The P rich layer around 20 to 40 nm in thickness calculating by the AES sputtering rate is produced at the initial stages of deposition and this layer is always stayed at the surface of the deposited film along with the advancement of deposition reaction.
The flow-injection amperometric determination of l-ascorbic acid with a laccase column was investigated. Laccase (EC 1. 10. 3. 1.) covalently immobilized onto porous glass beads was used as a recognition element for l-ascorbic acid. The immobilized enzymes were packed into a small polymer column, and then mounted in a water-jacketed holder. The biosensing system was assembled with the column unit and a flow-through type of an oxygen electrode for monitoring dissolved oxygen enzymatically consumed. l-Ascorbic acid was amperometrically determined in a range of 0.05-1.0 mM. In order to increase the amount of dissolved oxygen in the carrier stream, an electrolytic device was applied to the FIA system. Then, we could expand the linear range of the l-ascorbic acid determination from 0.05 to 2.0 mM by using the electrolytic device.
In order to save the energy for chlor-alkali electrolysis, the gas-diffusion has been investigated. We studied efforts of size and quantity of the silver-catalyst in electrode on the performance of electrodes. We used the fine powder of silver as size of 0.1≫1.0 µm. The performance of the electrodes prepared was evaluated by the measurement of the potential for the oxygen reduction in 32% NaOH at 80°C and 1 atm O2. The condition of silver-catalyst in electrode prepared was evaluated by SEM images and specific resistance. It was found that the electrode prepared with the size of 0.3 µm as silver-catalyst showed the highest performance and that the catalyst of this electrode was found most dispersed by SEM images. Finally, from this date it was believed that the great number of three-phase zone was formed by the dispersing effect and the best condition to prepare the maximum three-phase zone was found to be 2 mg/cm2 Ag. Less than this amount, the performance was lower, maybe due to the lowered number of the points of three-phase zone. On the other hand, when the electrode was loaded more than 17 mg/cm2 Ag, the performance also lowered, probably because the surface of the electrode had hydrophilicity. It was concluded that the best condition to prepare the oxygen reduction electrode for chlor-alkali electrolysis was to load 2 mg/cm2 Ag whose size was 0.3 µm and with this electrode, the electrolysis was taken place at 2.2 V-0.3 A/cm2.
The permeability of Cu2+ and CuCl+ across the cation exchange membrane of Ion-Exchange Electrodialyzer in aqueous solution of NaCl was examined using a mathematical model of the permeation rate. The mathematical model of the permeation rate of Cu(II) was developed based on the mathematical model of the permeation rate of model cations and the ratio of the copper species (Cu2+, CuCl+) estimated from stability constants. The permeation rates of Cu2+ and CuCl+ ions were calculated using this model and the experimental results. It was found that the permeation rate of Cu2+ has a significant effect on that of Cu(II) when the concentration of chloride ions is low, whereas the permeation rate of CuCl+ has a significant effect on that of Cu(II) when the concentration of chloride ions is high. Therefore, the characteristic behavior of the permeation rate of Cu(II) was verified quantitatively. Moreover, it was found that the behavior of the permeation rates of CuCl+ and Cu2+ are similar to those of monovalent cations such as K+ and divalent cations such as Ca2+, respectively.
Tetratitanic acid, H2Ti4O9·H2O, has a layer structure composed of the TiO6 octahedra sheets containing two protons and one water molecule per tetratitanate unit. The protons are exchanged with cations in bulk solution, and the amount of alkali metal ions incorporated into the interlayer was measured as a function of pH. With increasing pH, the amount increased, but the effect of pH on the extent of incorporation was far smaller than that expected from the mass action law. This behavior was modeled with the Frumkin equation where suppressive interactions between adsorbed ions owing to either electrostatic repulsion or steric hindrance are taken into account. The measured data were fitted with the model equation and the ion adsorption abilities of tetratitanic acid, adsorption affinities of sodium and potassium ions, and suppressive interaction properties of adsorbed ions were evaluated with model parameters. The molecular form of the exchanging protons and the mechanism of exchange with cations are discussed.
We developed a monitoring system for determining the excretion and urinary volume based on the changes in impedance of disposable diaper. This method has an advantage over other methods in that urinary volume can be measured without direct contact. The urinary volume was calculated based on the change rate of impedance. We found that the correlation coefficient between the urinary volume and the change rate of impedance was 0.96, suggesting the possibility of quantitative analysis. In addition, it was found that the slope between the urinary volume and the change rate of impedance was shifted by the movement of a person. The slope corrections were carried out using two acceleration sensors. Furthermore, we evaluated the monitoring system in a nursing home. The sensor output chart agreed with the motions obtained in a daily schedule and showed the urinary incontinence time.