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The development of a nonconventional nitrogen fertilizer, which can be fixed in agricultural fields using decentralized renewable energy sources, presents a feasible solution for sustainable on‐site nitrogen fixation and fertilization. This study focuses on plasma‐generated dinitrogen pentoxide (N2O5) as a prospective mediator for the on‐site nitrogen fertilization, allowing nitrogen fertilization directly into culture media. Basal dinitrogen pentoxide fertilization demonstrated almost 100% dinitrogen pentoxide dissolution efficiency as nitrate in a culture medium and nitrogen fertilization effect on plant growth without explicit symptoms of damage. Top‐dressing of dinitrogen pentoxide was also an efficient method for transferring nitrogen into the soil as nitrate, which improved plant growth and suppressed nitrogen deficiency symptoms, while overdose caused adverse effects. [ABSTRACT FROM AUTHOR]

Exposure to N2O5 generated by plasma technology activates immunity in Arabidopsis through tryptophan metabolites. However, little is known about the effects of N2O5 exposure on other plant species. Sweet basil synthesizes many valuable secondary metabolites in its leaves. Therefore, metabolomic analyses were performed at three different exposure levels [9.7 (Ex1), 19.4 (Ex2) and 29.1 (Ex3) μmol] to assess the effects of N2O5 on basil leaves. As a result, cinnamaldehyde and phenolic acids increased with increasing doses. Certain flavonoids, columbianetin, and caryophyllene oxide increased with lower Ex1 exposure, cineole and methyl eugenol increased with moderate Ex2 exposure and l-glutathione GSH also increased with higher Ex3 exposure. Furthermore, gene expression analysis by quantitative RT-PCR showed that certain genes involved in the syntheses of secondary metabolites and jasmonic acid were significantly up-regulated early after N2O5 exposure. These results suggest that N2O5 exposure increases several valuable secondary metabolites in sweet basil leaves via plant defense responses in a controllable system. [ABSTRACT FROM AUTHOR]

We have developed a new liquid‐phase noncatalytic selective oxidation of polyhydric alcohols such as glycerol. This method involves the use of a nonthermal atmospheric‐pressure plasma instead of precious‐metal catalysts. We found that noncatalytic selective oxidation of glycerol achieved a conversion comparable to that achieved by gold‐catalyzed oxidation, and the desired glyceric acid, which is a pharmaceutical raw material, was obtained. When the solution pH was changed from strongly alkaline to neutral, the main reaction switched from the one that occurs in the presence of gold catalysts to the one that occurs in the presence of platinum catalysts. These results suggest that the reactive oxygen species generated by nonthermal atmospheric‐pressure plasma irradiation vary depending on the solution pH. [ABSTRACT FROM AUTHOR]

Streamer discharges in water, which are a pre-breakdown phenomenon caused by underwater discharge, have gained attention because of the development of plasma-based technologies for water purification and medical treatment. In this study, a single-shot pulsed negative high voltage of –18 to –21 kV with a rise time of 100 ns was applied to a needle electrode in ultrapure water, and streamers were continuously imaged using an optical system combining a high-speed video camera, a streak camera, and an ultra-high-speed camera with a microscope lens. These observations were synchronized with the applied voltage and the discharge current to investigate the effect of the discharge on streamer propagation. Negative streamers propagated with a velocity of 820 ± 50 m/s in the presence of pulsed currents, and 100 ± 20 m/s when pulsed currents were absent. The streak camera detected light emission when the pulsed currents appeared, and it was also observed that 1480 m/s pressure waves were generated during streamer propagation. Furthermore, we developed a simple new method of imaging weak density changes similar to those detected using the Schlieren method or Mach–Zehnder interferometer. This method simply involves inserting a pair of polarizing plates on the optical axis, so that the pressure waves can also be imaged in two-dimensional photographs. Our results indicated that the pressure waves were generated from the propagating streamer head when the pulsed currents appeared in the waveform. Analysis of temporal resolution with nano-second order clarified that the branching phenomenon occurred at different times resulting in the branching streamer propagation with different directions. [ABSTRACT FROM AUTHOR]

Herein, we developed a near-invisible solar cell through a precise control of the contact barrier between an indium tin oxide (ITO) electrode and a monolayer tungsten disulfide (WS2), grown by chemical vapor deposition (CVD). The contact barrier between WS2 and ITO was controlled by coating various thin metals on top of ITO (Mx/ITO) and inserting a thin layer of WO3 between Mx/ITO and the monolayer WS2, which resulted in a drastic increase in the Schottky barrier height (up to 220 meV); this could increase the efficiency of the charge carrier separation in our Schottky-type solar cell. The power conversion efficiency (PCE) of the solar cell with the optimized electrode (WO3/Mx/ITO) was more than 1000 times that of a device using a normal ITO electrode. Large-scale fabrication of the solar cell was also investigated, which revealed that a simple size expansion with large WS2 crystals and parallel long electrodes could not improve the total power (PT) obtained from the complete device even with an increase in the device area; this can be explained by the percolation theory. This problem was addressed by reducing the aspect ratio (width/channel length) of the unit device structure to a value lower than a critical threshold. By repeating the experiments on this optimized unit device with an appropriate number of series and parallel connections, PT could be increased up to 420 pW from a 1-cm2 solar cell with a very high value (79%) of average visible transmission (AVT). [ABSTRACT FROM AUTHOR]