Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 67 , Issue 2
Showing 1-19 articles out of 19 articles from the selected issue
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Headline
  • Masuo AIZAWA, Sumihiro KOYAMA, Keisei KIMURA, Tetsuya HARUYAMA, Yasuko ...
    1999 Volume 67 Issue 2 Pages 118-125
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    The electric modulation of proliferation and differentiation has been performed by electrically stimulating cells that are cultured on the electrode surface in a controlled culture system. Mammalian cells such as HeLa cells halt proliferation at about +0.4V vs. Ag/AgCl without any fatal effects, and proliferate at a potential-dependent rate in the range from 0 to+0.4V vs. Ag/AgCl. Cells are cultured under a controlled rate of proliferation by setting the electrode potential at constant. When the electrode potential is modulated by low frequency of sine wave, the intracellular gene expression is activated, A resting stage of astroglial cells, halting excretion of nerve growth factor (NGF), start generating and excreting NGF by 1-hr electric stimulation at 10Hz with an amplitude of 0.3V, which results from enhancement of NGF mRNA. Differentiation of PC12 cells is also electrically induced to grow neurites in the absencence of NGF. The mechanisms of these electric effects are discussed.

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Technical Papers
  • Kenji SHINOHARA, Ryoichi AOGAKI
    1999 Volume 67 Issue 2 Pages 126-131
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    Magnetic Corrosion of copper in nitric acid was examined by the magnetic field up to 10T. Consequently, it was shown that strong magnetic field greatly affects corrosion rate. Then, the micro-MHD (magnetohy-drodynamic) effect on magnetic corrosion was newly proposed. This effect has two different roles for corrosion; one is the blocking effect, which decreases the corrosion rate with increasing magnetic flux densities. Another is the acceleration of the corrosion rate.

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  • Masaaki MATSUSHIMA, Shigetaro OGURA, Yoshioki HAJIMOTO
    1999 Volume 67 Issue 2 Pages 132-138
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    The packing densities, the water adsorption amount and the coloring efficiency of dielectric materials (WO3, ZrO2, Ta2O5, Al2O3 and ZnS) films and of the electrochromic devices (ECD) of these films which were evaporated at the various substrate temperature were investigated by the microbalance method of quartz oscillator. The films of WO3, ZrO2 and Ta2O5 were low packing densities and, therefore, large water adsorption amount. The ECD’ of ZrO2 and Ta2O5 had large water adsorption amount and high coloring efficiencies. However, the ECD’ of Al2O3 and ZnS had small water adsorption amount and could not be colored. In dry air the former ECD’ could not be colored. The humidity became higher, these coloring efficiency increased and at 50-60% humidity these coloring efficiency became the maximum. But the humidity increased from this range, the coloring efficiency became lower.

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  • Hiromitsu HIRAKAWA, Alfredo MAESTRE
    1999 Volume 67 Issue 2 Pages 139-144
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    The sedimentation potentia1 (SP) of 10 kinds of electrolytes in Water-Dimethylformamide mixtures are measured as a function of DMF composition. By combining SP obtained and law of additivity on ionic partial molar volume, limiting partial molar volumes of the electrolytes are divided into cationic and anionic parts at each DMF composition. As the result, ionic partial molar volume of Na+ and K+ ions except Na+ ion obtained from NaPh4B shows an increase tendency with concentration of DMF in between 15%~45%. In this case, the change of ionic partial molar volume of K+ ion is bigger than those of Na+ ion. On the contrary, ionic partial molar volume of Cl and Br ions except C1 ion obtained from Ph4PCI shows a decrease tendency with concentration of DMF in the Same region. Ionic partial molar volume of Br ion having alkyl group shows a big change among them. Ionic partial molar volume of Ph4P+ and Ph4B ions shows opposite change. From above fact, we discuss on the basis of ion-water, ion-DMF and ion-ion interactions.

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  • Xianming WANG, Tatsuo NISHINA, Isamu UCHIDA
    1999 Volume 67 Issue 2 Pages 145-150
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    Microelectrode technique was used to examine the stability of organic solutions and metals because of minimum iR effect on polarization behavior. By diluting the solution, we studied the electrochemical behavior of the solvent and solute separately ; PC, PC+EC solvents and LiClO4 solute were found to be oxidized at +5.73V, +5.77V and +4.40V, respectively. The cathodic decomposition of PC and PC+EC solvents occurred at negative potentials of 0V because of the freshly deposited lithium. The stability of various metals (Cu, Mo, Ni, Pd, SUS304, Al, Au, Pt and W) were examined in l M (M=mo1/dm3) LiClO4/PC solution and categorized according to their anodic and cathodic behaviors.

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Technological Reports
  • Kazuya IWAMOTO, Kazunori TAKADA, Makoto FUJINO, Shigeo KONDO
    1999 Volume 67 Issue 2 Pages 151-154
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    Solid state lithium battery, Li4/3+xTi5/3O4/Li1−xCoO2, was constructed by using a Li+ ion conductive sulfide glass as an electrolyte. The coin type battery with dimensions of 12mm in diameter and l.6mm in thickness had a discharge capacity of 2.8mAh. The battery showed an excellent cycling ability. There was no degradation in coulombic efficiency even in the case of continuous charging. It suggests that side reaction is negligible due to the electrochemical stability of the solid electrolyte.

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  • Mariko MAEDA, Akifusa HAGIWARA, Hiroko SOTOUCHI, Hidetaka SATO, Xing-z ...
    1999 Volume 67 Issue 2 Pages 155-159
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    In order to improve the durability of phosphoric acid fuel cells (PAFC), it is essential to suppress the corrosion rate of carbon, which is one of the important components. In this study, we examined the influence of the degree of graphitization of carbon materials on their corrosion rate in hot phosphoric acid. We found the higher the level of graphitized carbon the lesser corrosion rate. In the case of using a pitch as a precursor, a graphitization temperature of at least 2000℃ was needed to suppress the corrosion rate. Treatment at higher temperatures did not affect corrosion suppression. Alternatively, a layer dimension parameter-Lc or La-of over 200 or 300 was needed.

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  • Toshihiro INOUE, Nobuyuki KOURA
    1999 Volume 67 Issue 2 Pages 160-162
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    With the view to reduce electrode production process, it has been studied to produce a positive electrode by using pressed process in a sealed lead-acid cel1. The starting active materials for positive electrodes were prepared from lead dioxide. The utilization of pressed process electrode was about 75% for the current pasted process. It was caused by the low conductivity of a pressed active material and the pore distribution uniformity in a pressed active material. By adding lead sulfate to lead dioxide at the beginning of the process, the utilization of active material was improved. The positive electrode produced by the pressed process can be charged and discharged and it has the same cycle life as the current process. There is possibility of our developing the pressed process for a new electrode production process.

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  • Takakazu TAKANO, Seichi RENGAKUJI, Susumu IKENO, Yuuko NAKAMURA, Choic ...
    1999 Volume 67 Issue 2 Pages 163-169
    Published: February 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    In order to improve the cutting ability of drills or endmills, Fe-W alloy electroplating was used to increase the surface hardness of the machine tools. Furthermore, in order to increase the adhesive strength between the coated Fe-W alloy films and the high-speed steel substrate, Fe, Co and Cu were used as adhesives. Adhesive strength was measured by both scratch and indentation methods. After amealing at 550 °C, the critical load at which the fllms pull out was increased by the use of the adhesives. The order of increasing adhesive ability was Cu, Fe, Co and binder-less. On the other hand, the surface hardness measured by dynamic hardness tester showed Co to be best, followed by Fe, binder-1ess, then Cu, This sllggests that Fe is thought to be the most suitable for the binder metal. Cross-sectional analysis by ESCA showed an extensive diffusion of Cu, Fe, and Co into the Fe-W alloy film and the high-speed steel.

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