Hideo Nojima

Investigation on removal of hardness ions by capacitive deionization (CDI) for water softening applications.

Capacitive deionization (CDI) for removal of water hardness was investigated for water softening applications. In order to examine the wettability and pore structure of the activated carbon cloth and composites electrodes, surface morphological and electrochemical characteristics were observed. The highly wettable electrode surface exhibited faster adsorption/desorption of ions in a continuous treatment system. In addition, the stack as well as unit cell operations were performed to investigate preferential removal of the hardness ions, showing higher selectivity of divalent ions rather than that of the monovalent ion. Interestingly, competitive substitution was observed in which the adsorbed Na ions were replaced by more strongly adsorptive Ca and Mg ions. The preferential removal of divalent ions was explained in terms of ion selectivity and pore characteristics in electrodes. Finally, optimal pore size and structure of carbon electrodes for efficient removal of divalent ions were extensively discussed.

Galvanomagnetic Effect of an Y–Ba–Cu–O Ceramic Superconductor and Its Application to Magnetic Sensors

The galvanomagnetic effect of a ceramic superconductor Y1Ba2Cu3O7-x was measured. It was found that when a magnetic field of a certain small value applied, the electric resistance of this material suddenly increases very rapidly from zero with increases in the applied magnetic field. The magnetic field at which the resistance appears is controllable by changing the magnitude of a current through the material. This effect is characterized by a very high magnetic sensitivity at low magnetic field. This is quite useful as a highly sensitive magnetic sensor both in digital and analogue operations. This magnetic sensor using the ceramic superconductor has many advantages over the conventional semiconductor magnetoresistive sensor.

Air Purification Effect of Positively and Negatively Charged Ions Generated by Discharge Plasma at Atmospheric Pressure

In this paper, the air purification effect of positively and negatively charged ions generated by discharge plasma at atmospheric pressure is reported. We have developed a novel ion generation device which consists of a cylindrical glass tube and attached inner and outer mesh electrodes. With the application of AC voltage between the electrodes, positively charged ions and negatively charged ions have been generated at atmospheric pressure. The ion densities of 3.0×104–7.0×104 counts/cm3 have been obtained with the AC voltage of 1.8–2.3 kV (effective value). We have examined the air purification properties of this device. By the operation of this device, the initial oxygen nitride (NO) density of 10 ppm in 1 m3 (in cigarette smoke) was decreased to 1 ppm after 30 min. The number of suspended germs in air has been significantly reduced by the use of this type of ion generation device.

Fabrication of Ag-Doped Y1Ba2Cu3O7-x Superconducting Films on Cu Substrates by Electrophoretic Deposition

Ag-doped Y1Ba2Cu3O7-x superconducting films were fabricated on Cu substrates by electrophoretic deposition. The electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x and Ag2O powder dispersed in distilled acetone. The deposited films were heat-treated in air at 900°C. The Ag-doped Y1Ba2Cu3O7-x films on Cu-coated YSZ exhibited a metallic temperature dependence of the resistance, and the zero-resistance state was obtained at 88 K. The critical current density and the grain growth were greatly improved by the Ag doping.

Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air

Abstract A novel atmospheric pressure plasma device releasing atomic hydrogen has been developed. This device has specific properties such as (1) deactivation of airborne microbial-contaminants, (2) neutralization of indoor OH radicals and (3) being harmless to the human body. It consists of a ceramic plate as a positive ion generation electrode and a needle-shaped electrode as an electron emission electrode. Release of atomic hydrogen from the device has been investigated by the spectroscopic method. Optical emission of atomic hydrogen probably due to recombination of positive ions, H+(H2O)n, generated from the ceramic plate electrode and electrons emitted from the needle-shaped electrode have been clearly observed in the He gas (including water vapour) environment. The efficacy of the device to reduce airborne concentrations of influenza virus, bacteria, mould fungi and allergens has been evaluated. 99.6% of airborne influenza virus has been deactivated with the operation of the device compared with the control test in a 1 m3 chamber after 60 min. The neutralization of the OH radical has been investigated by spectroscopic and biological methods. A remarkable reduction of the OH radical in the air by operation of the device has been observed by laser-induced fluorescence spectroscopy. The cell protection effects of the device against OH radicals in the air have been observed. Furthermore, the side effects have been checked by animal experiments. The harmlessness of the device has been confirmed.

Fabrication of Y-Ba-Cu-O superconducting films on Cu substrates by an electrophoretic deposition technique

Direct formation of Y1Ba2Cu3O7-x films on Cu substrates by electrophoretic deposition is studied, Electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x powder dispersed in distilled acetone. The deposited films were annealed in air at 900°C. We succeeded in obtaining superconducting Y1Ba2Cu3O7-x films on Cu substrates. The films on Cu plates and Cu film/YSZ exhibited the zero-resistance state at 66 K and 76 K, respectively. Interfacial chemical reactions at the Y1Ba2Cu3O7-x/Cu interface are discussed. The achievement of the zero-resistance state is considered to be due to the reduction of the interfacial reactions.

Atomic Hydrogen Surrounded by Water Molecules, H(H2O)m, Modulates Basal and UV-Induced Gene Expressions in Human Skin In Vivo

Recently, there has been much effort to find effective ingredients which can prevent or retard cutaneous skin aging after topical or systemic use. Here, we investigated the effects of the atomic hydrogen surrounded by water molecules, H(H2O)m, on acute UV-induced responses and as well as skin aging. Interestingly, we observed that H(H2O)m application to human skin prevented UV-induced erythema and DNA damage. And H(H2O)m significantly prevented UV-induced MMP-1, COX-2, IL-6 and IL-1β mRNA expressions in human skin in vivo. We found that H(H2O)m prevented UV-induced ROS generation and inhibited UV-induced MMP-1, COX-2 and IL-6 expressions, and UV-induced JNK and c-Jun phosphorylation in HaCaT cells. Next, we investigated the effects of H(H2O)m on intrinsically aged or photoaged skin of elderly subjects. In intrinsically aged skin, H(H2O)m application significantly reduced constitutive expressions of MMP-1, IL-6, and IL-1β mRNA. Additionally, H(H2O)m significantly increased procollagen mRNA and also decreased MMP-1 and IL-6 mRNA expressions in photoaged facial skin. These results demonstrated that local application of H(H2O)m may prevent UV-induced skin inflammation and can modulate intrinsic skin aging and photoaging processes. Therefore, we suggest that modifying the atmospheric gas environment within a room may be a new way to regulate skin functions or skin aging.

Magnetic field dependence of voltage noise in Y1Ba2Cu3O7-x ceramic superconductor film

Magnetic field dependence of voltage noise in a ceramic superconductor Y1Ba2Cu3O7-x film has been investigated. We have observed a maximum of the noise at about 10 Oe for the perpendicular field to the film surface. For the parallel field to the film surface, the noise increases slightly with the increase of the field. These noise characteristics are considered due to a motion of magnetic flux in the film.

Effect of Cathode Length on Electrical Characteristics of a Microhollow Cathode Discharge in Helium

The electrical characteristics of a microhollow cathode discharge (MHCD) have been measured over a wide range of helium gas pressures from 10 to 900 Torr, by using cathodes of 0.5 mm diameter and 0.5–3.0 mm length. A relatively high voltage of the Paschen minimum at high pressure for the shortest cathode and a conventional hollow cathode mode for longer ones were observed. These are explained by a change of the plasma loss owing to the difference in cathode length. The radial extent of the negative glow inside the cathode hole increased with discharge current, and eventually spread along the outer surface. The threshold current for the extension of the plasma outside the cathode hole increased in proportion to the cathode length and to the square of the gas pressure. Thus, the longer cathode provides a favorable condition for the generation of reactive MHCD plasma at high-pressure and high-current operation. On the basis of these results and spectroscopic observation, the sustaining mechanism of an MHCD is briefly discussed.

Pressure Dependences of Gas Temperature and Electron Density in Microhollow Cathode Discharges in He and He+H2O Gases

Microplasmas were generated using a cylindrical hollow cathode with a diameter of 0.5 mm and a length of 3 mm in He and He+H2O gases at pressures in the range of 20 to 765 Torr. Spectral line profiles of He I (667.8 nm) and Hα (656.3 nm) were measured to determine the plasma parameters. Gas temperature and electron density were evaluated by the analysis of spectral line broadening. These parameters linearly increased with gas pressure in the range of 300 to 765 Torr. The gas temperatures and electron densities at atmospheric pressure were obtained to be 610 K and 5.0×1014 cm-3 for He and 820 K and 3.5×1014 cm-3 for He+H2O microplasmas, respectively. A comparison of these values with those obtained in a previous work [M. Miclea et al.: J. Phys. D 38 (2005) 1709] demonstrated that our device could generate high-density plasmas with a large volume and a high degree of nonequilibrium. The influences of an admixture of H2O on the discharge properties and plasma parameters were also discussed.