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To address the short lifetime of plasma‐activated water (PAW), this work reports on the application of ultralong‐lasting PAW for plant disease treatment. Compared with lettuce without ultralong‐lasting PAW treatment, the treated lettuce solution showed c. 1 log10 colony forming units mL−1 decrease in pathogens, as well as improvements in leaf area, leaf weight, root length, and root weight by 75%, 20%, 108.33%, and 150%, respectively. The leaf withering/root mortality rate of PAW‐treated plants was significantly lower than those of non‐PAW‐treated plants. Besides, disease defense‐related enzymes, such as catalase and β−1,3‐glucanase, were respectively enhanced by 112.5% and 5.13% in PAW‐treated lettuce, while the plant defense‐related genes were upregulated to respond to the pathogen's invasion. [ABSTRACT FROM AUTHOR]

In our recent work, we successfully developed an innovative method based on pin-water discharge for preparing ultralong-lasting plasma-activated water (PAW) with a lifetime of up to 720 hours at room temperature. However, the impact of power polarity on the preparation method for ultralong-lasting PAW remains unclear. In this study, we discovered that ultralong-lasting PAW could only be achieved with positive polarity. Further analysis of the liquid reactive oxygen and nitrogen species (RONS) revealed that the absence of H2O2 in the discharge chamber was crucial for the failure of ultralong-lasting PAW preparation at negative polarity. To elucidate the mechanism underlying the generation of RONS at different polarities, we conducted plasma feature diagnosis, compared discharge morphologies, and performed theoretical analyses based on chemical reactions. Our results indicated that the introduction of water vapor molecules through intense spraying at positive polarity led to an increase in the generation of H2O2-related source particles, while also interfering with N2-related electron collision reactions and chemical reaction coefficients, ultimately affecting the production of NO2−. Consequently, there was relatively less liquid NO2− and more abundant H2O2 in the discharge chamber at positive polarity, whereas the opposite trend was observed for these two key RONS at negative polarity. Furthermore, the minimal amount of NO2− at positive polarity and the tiny amount of H2O2 at negative polarity in the discharge chamber would be respectively consumed by the relatively abundant H2O2 at positive polarity and NO2− at negative polarity. [ABSTRACT FROM AUTHOR]

Nitrogen oxide‐generating dielectric barrier discharge plasma is shown to effectively inhibit microorganisms and maintain fruit freshness. Physical and biological mechanisms of the plasma‐electrified fungicidal effects suggest that plasma‐generated NO and ONOO− species and other factors are crucial to regulating physiological senescence in citrus fruit while controlling pathogens on their surface. The revealed Physico‐chemical effects explain the observed phenotypic changes and the suppression of surface pathogens, thus providing mechanistic insights into postharvest fruit processing with plasmas. [ABSTRACT FROM AUTHOR]

Plasma-activated water (PAW) represents a promising green antibacterial agent for biomedical and agricultural applications. In this study, a novel AC multi-needle-to-water discharge device was developed to investigate the effects of gas flow on the generation and chemical composition of PAW. It is shown that the concentrations of and N(III) (and) in the PAW both increased with an extension of the plasma-processing time and a reduction of the gas-flow rate. The absorption of gas-phase products carried by the gas flow from the discharge chamber was found to be beneficial for the generation of both and N(III) in the PAW at a gas flow rate of 20–60 L h−1, yet their concentrations were still lower than those without any feeding gas. As opposed to or N(III), the concentration in the plasma-activated phosphate buffer solution (PAPBS) increased under stronger gas flows and was almost unaffected by absorption in PAPBS. The pH value of PAW increased at higher gas flow rates. A comparison of the N(III) in PAW and PAPBS reflects the effects of the reactions of and in the two different working liquids. To quantify the effects of gas flow on the discharge characteristics, gas temperatures were calculated from the optical emission spectra and were proven to be flow-independent near the discharge channel. Fourier transform infrared (FTIR) measurements of the gaseous products during the discharge, and further analysis of possible reaction pathways indicated that by controlling the gas flow in the multi-needle-to-water discharge system, the concentration of long-lived species in PAW could be tuned, which might favor the generation of These findings contribute to a better understanding of effective electric discharge-related mechanisms for enhancing the biochemical and chemical activities of PAW. [ABSTRACT FROM AUTHOR]