Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, −20 °C, −80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at −80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and −20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, −20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3−. Moreover, PAW stored at −80 °C retained bactericidal activity, with NO2− contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation.

A highly enantioselective intramolecular arylative dearomatization of indoles via palladium-catalyzed reductive Heck reactions was developed. The new strategy led to a series of optically active indolines bearing C2-quaternary stereocenters in modest to good yields with excellent enantioselectivities (up to 99% ee).

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In recent years, plasma-activated solutions (PASs) have made good progress in the disinfection of medical devices, tooth whitening, and fruit preservation. In this study, we investigated the inactivation efficacy of Newcastle disease virus by PASs. Water, 0.9% NaCl, and 0.3% H2O2 were excited by plasma to obtain the corresponding solutions PAS(H2O), PAS(NaCl), and PAS(H2O2). The complete inactivation of virus after PAS treatment for 30 min was confirmed by the embryo lethality assay (ELA) and hemagglutination (HA) test. Scanning electron microscopy (SEM) results showed that the morphology of the viral particle changed under PAS treatments. The total protein concentration of virus decreased as measured by a Bradford protein assay due to PAS treatment. The nucleic acid integrity assay demonstrated that viral RNA degraded into smaller fragments. Moreover, the physicochemical properties of PASs, including the oxidation-reduction potential (ORP), electrical conductivity, and H2O2 concentration, and electron spin resonance spectra analysis indicated that reactive oxygen and nitrogen species play a major role in the virus inactivation. Therefore, the application of PASs, as an environmentally friendly method, would be a promising alternative strategy in poultry industries.IMPORTANCE Newcastle disease (ND), as an infectious viral disease of avian species, caused significant economic losses to domestic animal and poultry industries. The traditional chemical sanitizers, such as chlorine-based products, are associated with risks of by-product formation with carcinogenic effects and environmental pollution. On the basis of this, plasma-activated water as a green disinfection product is a promising alternative for applications in stock farming and sterilization in hospitals and public places. In this study, we explored the inactivation efficacy of different plasma-activated solutions (PASs) against ND virus (NDV) and the possible underlying mechanisms. Our results demonstrated that reactive oxygen and nitrogen species detected in PASs, including short-lived OH˙ and NO˙ and long-lived H2O2, changed the morphology, destroyed the RNA structure, and degraded the protein of the virus, consequently resulting in virus inactivation. These lay a foundation for the application of PASs to resolve the issues of public health and environmental sanitation.

Palladium-catalyzed enantioselective dearomative arylalkynylation of N-substituted indoles, through a Heck/Sonogashira sequence, was established using a new BINOL-based phosphoramidite as the chiral ligand. A wide range of 2,3-disubstituted indolines, bearing vicinal quaternary and tertiary stereocenters, were efficiently constructed in one step with excellent enantioselectivities (up to 97 % ee) and diastereoselectivities (>20:1).