Shoko Tago

Application of Boron-Doped Diamond Microelectrodes for Dental Treatment with Pinpoint Ozone-Water Production

Ozone is known to act as a powerful antimicrobial agent against bacteria, fungi, and viruses. The strong oxidation ability of ozone induces the destruction of bacterial cell walls, cytoplasmic membranes, and biomolecules on the bacterial cell surface. Recently, ozone has received growing attention as a useful tool for dental treatment. Ozone has a severely disruptive effect on cariogenic bacteria, resulting in the elimination of acidogenic bacteria. However, while laboratory studies suggest a promising potential of ozone in dentistry, this has not been fully realised in clinical studies to date. In this study, a novel pinpoint ozone-water production unit for dental treatment using boron-doped diamond (BDD) microelectrodes was developed. The application of BDD electrodes is promising for electrolyzing water to produce ozone, because of their superior chemical and dimensional stability, as well as their large overpotential for the oxygen-evolution reaction. 9] Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as test bacteria to assess the disinfection efficiency of the units. The BDD microelectrodes were prepared by method reported previously which has already been established for applications in in vivo detection. The BDD thin film was deposited on a prepared tungsten wire using a microwave-plasma-assisted chemical-vapor deposition system. Prior to BDD deposition, the tungsten wire was shaped by electrochemical etching to achieve a very small wire diameter. The as-prepared BDDcoated tungsten wires can then be used to fabricate microelectrodes with very small wire diameters (500 mm). A scanning electron microscopy (SEM) image of such a fabricated BDD microelectrode shows that the wire diameter is small (500 mm) with the polycrystalline diamond grain size being approximately 2 mm (Figure 1 a). The Raman spectrum (excitation wavelength: 532 nm) of the BDD microelectrode

Fabrication of a Porous TiO 2 -Coated Silica Glass Tube and Its Application for a Handy Water Purification Unit

A simple, handy, reusable, and inexpensive water purification unit including a one-end sealed porous amorphous-silica (a-silica) tube coated with 2 μm of porous TiO2 photocatalyst layers has been developed. Both TiO2 and a-silica layers were formed through outside vapor deposition (OVD). Raman spectrum of the porous TiO2-coated a-silica glass tube indicated that the anatase content of the TiO2 layers of the tube was estimated to be approximately 60 wt%. Developed porous TiO2-coated a-silica glass tube has been assayed for the tube filtering feature against Escherichia coli (E. coli) solution used as one of the typical bacteria size species or Q phage also used as typical virus size species and compared with the feature of porous a-silica tubes alone. The tubes removed E. coli completely from the aqueous suspension which contained 106 CFU/mL of E. coli without UV irradiation. The porous TiO2-coated a-silica glass tube with UV-C lamps successfully reduced the Q phage amount in the suspension from 109 to 103 PFU/mL.

Flexible Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring

Detecting the bio-potential changes of plants would be useful for monitoring their growth and health in the field. A sensitive plant monitoring system with flexible boron-doped diamond (BDD) electrodes prepared from BDD powder and resin (Nafion or Vylon-KE1830) was investigated. The properties of the electrodes were compared with those of small BDD plate-type electrodes by monitoring the bioelectric potentials of potted Aloe and hybrid species in the genus Opuntia. While flexible BDD electrodes have wide potential windows, their cyclic voltammograms are different from those of the BDD plate. Further, the potential gap between a pair of electrodes attached to the plants changes as the plants are stimulated artificially with a finger touch, suggesting that the bioelectric potentials in the plant also changed, manifesting as changes in the potential gap between the electrodes. The BDD electrodes were assessed for their response reproducibility to a finger stimulus for 30 days. It was concluded that the plant monitoring system worked well with flexible BDD electrodes. Further, the electrodes were stable, and as reliable as the BDD plate electrodes in this study. Thus, a flexible and inexpensive BDD electrode system was successfully fabricated for monitoring the bioelectric potential changes in plants.