In this study, nitrogen fixation in the electrolyte was achieved by atmospheric pressure non-thermal plasma generated by a sinusoidal power supply (with an applied voltage of 10 kV and frequency of 33 kHz). Ammonia measurements on plasma exposed electrolyte at several working gas and purging gas conditions revealed that nitrogen plasma on the same gas environment is more favorable for plasma-assisted ammonia synthesis. In addition, photo-electrochemical water splitting was performed by irradiating UV light (316 nm) on a titanium dioxide semiconductor photo-anode to generate hydrogen donor in nitrogen reduction reaction. The amount of ammonia synthesized by this synergistic process of photo-electrochemical water splitting and nitrogen plasma is six times higher than that obtained by nitrogen plasma alone. An increase in the co-synthesized N O X concentrations and background contamination at reaction site reduces the ammonia synthesis rate and Faraday efficiency. However, the ammonia production efficiency was increased up to 72% by using a proton-exchange membrane which prevent the diffusion of oxygen evolved from water splitting into the plasma, and by reducing the axial distance between the plasma electrode and reaction site. The sustainable nitrogen fixation process reported herein can be performed at atmospheric pressure conditions without a direct input of hydrogen gas or any catalyst.

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Ozone has been used for surface disinfection to contain bacterial, fungal, mold, and certain viral infections; however, the use of ozone generated from nonthermal plasma devices have not been thoroughly investigated for surface disinfection. Here, we aimed to determine the impact of nonthermal plasma‐generated ozone (PGO) on the coronavirus. Human coronavirus 229E was exposed to PGO and its infectivity was evaluated. PGO exposure of approximately 7 ppm reduced the viral titer after 4 h. Our results indicate that PGO exposure not only reduces the expression of the viral nucleocapsid gene and spike glycoprotein levels but may also stimulate the expression of the antiviral response gene in host cells. These findings can thus be useful to support existing surface disinfection methods.

This study investigated the effects of plasma duration and different reactive species ratios of cold atmospheric-pressure plasma treatment on both physical and endogenous hormone changes in enhancing the germination and growth of mung bean seeds. Seed germination and sprout stem length were significantly enhanced after plasma treatment. The germination rate increased eleven times after 12 h, while the radicles’ length increased ~3 times after 96 h with optimal plasma treatment parameters. SEM images showed that the plasmas directly induced gradual changes in the seed coating, including deformed and shrunken epidermis, and cracks with sizes varying from 0.2 to 1.5 µm after 4 min of plasma treatment. Water contact angle was reduced from 73° with untreated seed to almost 0° with 4 min treated seed. These effects could lead to better water absorption on the surface of treated seeds. We found that a plasma energy dosage of 0.08 Wh per seed and NO concentration between 20–95 ppm were the optimal enhancement conditions. We also showed that, for the first time, through delicate extraction, separation, and quantification processes, NO-induced upregulation of the natural growth hormone gibberellic acid could be the dominant phytochemistry pathway responsible for the enhancement effect.

Excess amounts of redox stress and failure to regulate homeostatic levels of reactive species are associated with several skin pathophysiologic conditions. Nonmalignant cells are assumed to cope better with higher reactive oxygen and nitrogen species (RONS) levels. However, the effect of periodic stress on this balance has not been investigated in fibroblasts in the field of plasma medicine. In this study, we aimed to investigate intrinsic changes with respect to cellular proliferation, cell cycle, and ability to neutralize the redox stress inside fibroblast cells following periodic redox stress in vitro. Soft jet plasma with air as feeding gas was used to generate plasma-activated medium (PAM) for inducing redox stress conditions. We assessed cellular viability, energetics, and cell cycle machinery under oxidative stress conditions at weeks 3, 6, 9, and 12. Fibroblasts retained their usual physiological properties until 6 weeks. Fibroblasts failed to overcome the redox stress induced by periodic PAM exposure after 6 weeks, indicating its threshold potential. Periodic stress above the threshold level led to alterations in fibroblast cellular processes. These include consistent increases in apoptosis, while RONS accumulation and cell cycle arrest were observed at the final stages. Currently, the use of NTP in clinical settings is limited due to a lack of knowledge about fibroblasts’ behavior in wound healing, scar formation, and other fibrotic disorders. Understanding fibroblasts’ physiology could help to utilize nonthermal plasma in redox-related skin diseases. Furthermore, these results provide new information about the threshold capacity of fibroblasts and an insight into the adaptation mechanism against periodic oxidative stress conditions in fibroblasts.