Inactivation of SARS-CoV-2 variants by nitrogen-doped titanium dioxide loaded with metals as visible-light photocatalysts.

PURPOSE: We examined the inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by a nitrogen-doped titanium dioxide (N-TiO2) visible-light photocatalyst that was activated via light irradiation in the natural environment and was safe for human use as a coating material. METHODS: The photocatalytic activity of glass slides coated with three types of N-TiO2 without metal or loaded with copper or silver and copper was investigated by measuring acetaldehyde degradation. The titer levels of infectious SARS-CoV-2 were measured using cell culture after exposing photocatalytically active coated glass slides to visible light for up to 60 min. RESULTS: N-TiO2 photoirradiation inactivated the SARS-CoV-2 Wuhan strain and this effect was enhanced by copper loading and further by the addition of silver. Hence, visible-light irradiation using silver and copper-loaded N-TiO2 inactivated the Delta, Omicron, and Wuhan strains. CONCLUSION: N-TiO2 could be used to inactivate SARS-CoV-2 variants, including emerging variants, in the environment.

A 2.0-GHz compact ESR spectrometer for monitoring automobile lubrication oil degradation.

This article reports a simple, compact, and cost-effective electron spin resonance (ESR) spectrometer for monitoring automobile lubrication oil degradation. Lubrication oil degradation strongly correlates with the concentration of stable free radicals caused by hydrocarbon chain decomposition due to heating. For the prototype spectrometer, the amplitude shift in a marginal oscillator output detects ESR absorption in a sample. The spectrometer's spin sensitivity of 2.3 × 1014 spins for a used oil sample was achieved using the marginal oscillator with a loop-gap resonator. For the prototype spectrometer, the oscillation frequency was 2.09 GHz. The volume of the prototype spectrometer was 1.3 L, including a permanent magnet, microwave circuits, and digital communication circuitry on printed circuit boards. The weight of the spectrometer setup was 1.45 kg. This prototype spectrometer successfully detected the ESR signal from a 50 µL oil sample (spin concentration 8.3 x1019 spins/L) with a signal-to-noise ratio of 37 and an acquisition time of 30 s.

Dioxanone-fused dienes enable highly endo-selective intramolecular Diels-Alder reactions.

Intramolecular Diels-Alder reactions of dioxanone-fused (Z,Z)-dienes, available in a stereoselective manner from the corresponding alcohols are described. These dienes exhibited high reactivity and high levels of endo selectivity, giving functionalized trans-fused bicyclic compounds.