Optimized parameters for effective SARS-CoV-2 inactivation using UVC-LED at 275 nm.

The spread of SARS-CoV-2 infections and the severity of the coronavirus disease of 2019 (COVID-19) pandemic have resulted in the rapid development of medications, vaccines, and countermeasures to reduce viral transmission. Although new treatment strategies for preventing SARS-CoV-2 infection are available, viral mutations remain a serious threat to the healthcare community. Hence, medical devices equipped with virus-eradication features are needed to prevent viral transmission. UV-LEDs are gaining popularity in the medical field, utilizing the most germicidal UVC spectrum, which acts through photoproduct formation. Herein, we developed a portable and rechargeable medical device that can disinfect SARS-CoV-2 in less than 10 s by 99.9%, lasting 6 h. Using this device, we investigated the antiviral effect of UVC-LED (275 nm) against SARS-CoV-2 as a function of irradiation distance and exposure time. Irradiation distance of 10-20 cm, < 10 s exposure time, and UV doses of > 10 mJ/cm2 were determined optimal for SARS-CoV-2 elimination (≥ 99.99% viral reduction). The UVC-LED systems have advantages such as fast-stabilizing intensity and insensitivity to temperature, and may contribute to developing medical devices capable of containing SARS-CoV-2 infection. By demonstrating SARS-CoV-2 inactivation with very short-term UVC-LED irradiation, our study may suggest guidelines for securing a safer medical environment.

Surface Characterizations of Railway Electrical Wires Coated with Anti-Icing Mixtures of Ethylene Glycol or Glycerol with Tap Water.

Icing of railway contact wires in the cold climates of the USA, Canada, China, Japan, and South Korea can cause significant problems and delays in the operation schedules of electric-powered trains and subway cars. As anti-icing methods, manual de-icing, contact-wire thermal running, resistive-wire-heating de-icing, and chemical de-icing have all been explored and tested. Among them, environmentally friendly chemical de-icing based on the same concept as that of automobileengine antifreezer can be practically effective for application to contact wires at railcar depots. In the present study, the railway contact wires are coated with anti-icing mixtures of ethylene glycol/tap water and glycerol/tap water at various ratios (v/v %) as well as with tap water alone, at temperatures of -30 and -40 °C in a deep freezer. The morphological change on the wire surfaces is observed under optical microscopy. The surface-contact angles are measured to examine the surface difference between uncoated and coated railway contact-wire fragments. Conclusively, the fragments coated with 40/60 and 60/40 (v/v %) ratios of ethylene glycol or glycerol with tap water, as compared with the uncoated fragments, are shown to have been effectively de-iced. The surface-characterizations data thus indicate that mixtures of glycerol or ethylene glycol with tap water can be practical de-icing agents for application to railway contact wires.