We investigated the antiviral activity of nanosized copper(I) iodide (CuI) particles having an average size of 160 nm. CuI particles showed aqueous stability and generated hydroxyl radicals, which were probably derived from monovalent copper (Cu ؉ ). We confirmed that CuI particles showed antiviral activity against an influenza A virus of swine origin (pandemic [H1N1] 2009) by plaque titration assay. The virus titer decreased in a dose-dependent manner upon incubation with CuI particles, with the 50% effective concentration being approximately 17 g/ml after exposure for 60 min. SDS-PAGE analysis confirmed the inactivation of the virus due to the degradation of viral proteins such as hemagglutinin and neuraminidase by CuI. Electron spin resonance (ESR) spectroscopy revealed that CuI generates hydroxyl radicals in aqueous solution, and radical production was found to be blocked by the radical scavenger N-acetylcysteine. Taken together, these findings indicate that CuI particles exert antiviral activity by generating hydroxyl radicals. Thus, CuI may be a useful material for protecting against viral attacks and may be suitable for applications such as filters, face masks, protective clothing, and kitchen cloths.

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Selective catalytic oxidation (SCO) of NH3 to harmless N2 and H2O is an ideal technology for its removal. To develop air purification systems for a living environment, catalysts that can work at room temperature with high selectivities to N2 are required. However, it has been a technical challenge because the reported catalysts either needed high operating temperatures or showed low selectivities to N2. In this study, we first demonstrated that acidic metal-oxide-supported gold catalysts showed good N2 selectivities compared with that of other metal-oxide-supported gold catalysts. A gold catalyst with niobium oxide synthesized by the hydrothermal method as a support showed high catalytic activity and high selectivity to N2 at low temperatures (18% NH3 conversion with 100% N2 selectivity at 25 °C) and at high temperatures (100% NH3 conversion with 95% N2 selectivity at 245 °C). Important roles of Brønsted acid sites and formation of active oxygen sites in improving N2 selectivity were revealed in this study. To the best of our knowledge, this is the first report of efficient catalysts that presented high NH3 conversion with high N2 selectivity at 25 °C which will offer great scopes for commercial applications related to control of odors. In addition, this breakthrough finding that acid sites would greatly affect N2 selectivity and catalytic activity will provide a new trend in designing efficient catalysts not only for SCO of NH3 but also for the other selective catalytic oxidation.

A titanium nitride (TiN) electrode with very low resistance and good electrochemical stability was constructed and used for electrochemical inactivation of the marine Gram-negative bacterium Vibrio alginolyticus. Specific resistance of the TiN electrode, which was formed by reactive sput tering, was 1.1 × 10-4 Ω·cm. When cyclic voltammetry of the TiN electrode-attached V. alginolyticus cells of 4.2 × 105 cells/cm2 was carried out at a scan rate of 20 mV/s in seawater, an anodic peak current appeared around 0.68 V vs Ag/AgCl. In all, 98.7% of V. alginolyticus cells attached onto the electrode were inactivated by applying a potential of 0.8 V vs Ag/AgCl in seawater for 30 min. Changes in pH and chlorine concentration were not observed at 0.8 V vs Ag/AgCl. The TiN electrode was oxidized by applying potential of a 0.8 V vs Ag/AgCl and passivated by formation of TiO2 onto the electrode surface. The TiO2 thin layer formed on the TiN electrode surface did not impede electrochemical inactivation of marine bacteria. These results show that the TiN electrode can be used as an electrode for electrochemical inactivation of marine bacteria.

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