Effect of Applying Cold Plasma on Structural, Antibacterial and Self Cleaning Properties of α-Fe2O3 (HEMATITE) Thin Film

Objective: In this study, α-Fe2O3 thin film was formed on a glass substrate to study the impact of adding cold plasma on the self-cleaning and antibacterial properties of the samples. Method: The samples were synthesized using the chemical spray pyrolysis (CSP) method at 450°C. X-ray powder diffraction (XRD), scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscope were used to investigate the morphological and structural characteristics of α-Fe2O3 thin layers prior to and following plasma injection. Finding: The degree of wettability and antibacterial characteristics of iron oxide (hematite) thin film were evaluated in the presence of gram-negative and gram-positive bacteria prior to and following plasma injection, given the great potential of plasma injection in the surface modification of thin films. Novelty: The findings indicate that exposing plasma to α-Fe2O3thin film produces substantial changes in morphology, self-cleaning, and antibacterial characteristics. Doi: 10.28991/ESJ-2022-06-01-06 Full Text: PDF

Influence of Atmospheric Cold Plasma Exposure on Naturally Present Fungal Spores and Physicochemical Characteristics of Sundried Tomatoes (Solanum lycopersicum L.)

This research aimed to evaluate the impact of atmospheric cold plasma (ACP) treatment on the fungal spores naturally present in sundried tomatoes, as well as their influence on the physico-chemical properties and antioxidant activity. ACP was performed with a Surface Dielectric Barrier Discharge (SDBD), applying 6 kV at 23 kHz and exposure times up to 30 min. The results showed a significant reduction of mesophilic aerobic bacteria population and of filamentous fungi after the longer ACP exposure. In particular, the effect of the treatment was assessed on Aspergillus rugulovalvus (as sensible strain) and Aspergillus niger (as resistant strain). The germination of the spores was observed to be reliant on the species, with nearly 88% and 32% of non-germinated spores for A. rugulovalvus and A. niger, respectively. Fluorescence probes revealed that ACP affects spore viability promoting strong damage to the wall and cellular membrane. For the first time, the sporicidal effect of ACP against A. rugulovalvus is reported. Physicochemical parameters of sundried tomatoes such as pH and water activity (aw) were not affected by the ACP treatment; on the contrary, the antioxidant activity was not affected while the lycopene content was significantly increased with the increase in ACP exposure time (p ≤ 0.05) probably due to increased extractability.

Towards Catalysts Prepared by Cold Plasma

Cold (non-equilibrium) plasma techniques have long been used as plasma deposition methods to create new materials, often with unique properties, which cannot be produced any other way, as well as plasma treatment methods for the sophisticated modification of conventional materials [...]

Characterization of the Flavor Profile of Bigeye Tuna Slices Treated by Cold Plasma Using E-Nose and GC-IMS

To avoid heat, treatment induces numerous physicochemical changes under severe conditions in the tuna, cold plasma (CP), as a non-thermal technology, possess objective potential on tuna processing. The effect of cold plasma on the volatile flavor compounds of bigeye tuna (Thunnus obesus) sashimi has been evaluated using electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS). GC–IMS results revealed a total of 33 volatile compounds in tuna slices. The effect of CP treatment on tuna flavor was not significant, furthermore CP could protect volatile freshness compounds such as 1-hexanol. Principal component analysis (PCA) of the E-nose and GC–IMS results could effectively differentiate the effect of storage to tuna sashimi. There was a high correlation between the E-nose and GC–IMS results, providing a theoretical basis for establishing the flavor fingerprint of tuna sashimi.

Preparation of N-doped graphite oxide for supercapacitors by NH3 cold plasma

In this work, N-doped graphite oxide (GO-P) was prepared by cold plasma treatment of GO using a mixture of NH3 and Ar as the working gas. When the ratios of NH3:Ar were 1:2, 1:3, and 1:4, the specific capacitances of the GO-P(NH3:Ar1:2), GO-P(NH3:Ar1:3), and GO-P(NH3:Ar1:4) were 124.5, 187.7, and 134.6 Fg−1, respectively, which were 4.7, 7.1, and 5.1 times that of GO at the current density of 1 Ag−1. The capacitance retention of the GO-P(NH3:Ar1:3) was 80% when it was cycled 1000 times. The characterization results showed that the NH3 cold plasma could effectively produce N-doped GO and generate more active defects. The N/C ratio and the contents of pyridinic nitrogen and graphitic nitrogen of the GO-P(NH3:Ar1:3) were the highest. These were conducive to providing pseudocapacitance and reducing the internal resistance of the electrode. In addition, the ID/IG of the GO-P(NH3:Ar=1:3) (1.088) was also the highest, indicating the highest number of defects. The results of discharge parameters measurement and in situ optical emission spectroscopy diagnosis of NH3 plasma showed that the discharge is the strongest when the ratio of NH3:Ar was 1:3, thereby the generated nitrogen active species can effectively promote N-doping. The N-doping and abundant defects were the keys to the excellent electrochemical performance of the GO-P(NH3:Ar1:3). NH3 cold plasma is a simple and rapid method to prepare N-doped GO and regulate the N-doping to prepare high-performance supercapacitors.

Cold Plasma as a Potential Activator of Plant Biostimulants

Agriculture has become a sector with a huge impact on the natural environment. The interest of agriculture in the category of innovative bio-stimulants is due to the intensive search for preparations based on natural substances. This is not possible without developing and implementing innovative technologies, e.g., cold plasma, along with innovative technologies supporting farmers. Therefore, given the need to prevent environmental damage caused by intensive agriculture, plant production and protection must be targeted at merging the stimulation of crop growth and the elimination of threats to humans and the environment. The analysis of how cold plasma can influence the production of organic bio-stimulants seems to be an unavoidable step in future approaches to this topic. Since allelopathic plants represent a source of many chemical compounds promoting crop growth and development, the coupling of biologically-active compound extraction with plasma activation of allelopathic extracts has interesting potential in offering the most modern alternative to conventional agriculture. However, its implementation in practice will only be feasible after a comprehensive and thoughtful investigation of the mechanisms behind crops’ response to such bio-stimulants.