山田 修

Porous TiC ceramic powder was used as a novel substrate for the surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) analysis of various environmental pollutants. The porous TiC ceramic powder has a nano-structural morphology with a high surface area, an electrical conductivity, and a photoabsorption at the Nd:YAG laser band of 355 nm. These properties of the porous TiC ceramics suggest having a good compatibility as a substrate for SALDI-MS. Furthermore, the porous TiC ceramic powder can be used as an adsorbent for environmental pollutants. The porous TiC ceramic powder was added to a perfluorooctane sulfonate (PFOS) aqueous solution. The liquid was shaken for 2 h, and PFOS was adsorbed onto the TiC ceramics. The liquid was filtered, and the residue was dried. The obtained powder was fixed on a carbon tape and measured by SALDI-MS in the negative ion mode. As a result, the peak assignable to PFOS (C8F17SO3 −) was detected, and no other significant peaks at m/z 100–500 were observed. As for the other analytes, the ion peaks corresponding to the anions or cations derived from these compounds in the negative or positive ion mode were observed using the same treatments.

Combustion-synthesized titanium carbide ceramics uniformly disperse silver, producing silver ions and hydroxyl radicals in water. This generates antimicrobial activity against various bacteria. One such bacterium is Streptococcus mutans, a gram-positive anaerobic bacterium known as a major pathogen of dental caries. In this study, we analyzed the inhibition of oral biofilms and S. mutans by ceramic water in in vitro and human studies. S. mutans strains showed significantly lower antimicrobial and sucrose-dependent adhesion activity in the presence of ceramic powder compared with untreated culture medium. Confocal microscopy revealed that S. mutans biofilm structures with ceramic powder were thin and coarse. Twenty-seven volunteers (13 males, 14 females; 18-37 years old, mean 25.2 years) were enrolled for subsequent studies. After each meal, one group was asked to rinse with ceramic water while the other rinsed with untreated water for 1 week. After 1 week, the rinsing contents were switched between the groups and the same protocol was followed for an additional week. After rinsing with ceramic water, the average plaque score was 43.0 +/- 3.7, which was significantly lower than the baseline value (74.1 +/- 5.7, p < 0.001). However, no significant difference was observed when rinsing with untreated water. In addition, the total number of S. mutans in saliva was significantly reduced after rinsing with ceramic water compared with untreated water (p < 0.05). These results suggest that ceramic water possesses antimicrobial activity against S. mutans and inhibits biofilm formation. Rinsing with ceramic water can also inhibit dental plaque formation and S. mutans colonization in humans. (C) 2016 S. Karger AG, Basel

The aim of this study is to investigate the utilization of the powder of porous titanium carbide (TiC) ceramics as a novel adsorbent or a material for solid-phase extraction (SPE). The adsorption and elution of inorganic and organic pollutants, Pb(II), 2,4,6-trichlorophenol (TCP), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA), to the material were evaluated. The cartridge packed with TiC ceramics powder was used for the extraction test of pollutants. The solution containing pollutants at 1.0 mu g mL(-1) was passed through the TiC cartridge, and the substances were almost quantitatively removed. Furthermore, the pollutants retained in the cartridge were eluted with 3 N HCl for Pb(II) and with methanol for organic pollutants. The recoveries of pollutants were over 80%. In addition, we used the TiC cartridge for the solid-phase extraction of water samples (500 mL each of the distilled water and the river water) by adding pollutants at determined concentrations. Every pollutant was adsorbed almost quantitatively, and eluted by 3 N HCl or methanol. From these results, we concluded that the powder of porous TiC ceramics is a useful reusable adsorbent for the water cleanup and solid-phase extraction. (C) 2010 Elsevier B.V. All rights reserved.