The subject of this paper is the recently developed 2.45 GHz microwave micro torch, which produces a surface wave discharge operating at low power of 25 W. Microwave plasma is generated using surfatron resonator in pure argon and argon with admixtures (up to 1.7%) of nitrogen and oxygen at the gas flow rate of 3 Slm. Two different configurations are used-a standard one and one with an additional metallic plate at the surfatron resonator end limiting the surface wave propagation along the plasma. Plasma parameters like temperatures (rotational, vibrational, electron) along the plasma torch axis as well as distribution of selected active particles are determined. The numeric simulation of the discharge and its properties are included, too. Finally, surface temperature of the fresh pork skin affected by the active particles flow is determined using thermo camera images. The obtained results show applicability of this system for the surface treatment of biological objects and possibility to modify the torch conditions by molecular gases additions.
Demand for food quality and extended freshness without the use of harmful chemicals has become a major topic over the last decade. New technologies are using UV light, strong electric field, ozone and other reactive agents to decontaminate food surfaces. The low-power non-equilibrium (cold) atmospheric pressure operating plasmas effectively combines all the qualities mentioned above and thus, due to their synergetic influence, promising results in fruit surface decontamination can be obtained. The present paper focuses on the applicability of the recently developed microwave surface wave sustained plasma torch for the treatment of selected small fruit. Optical emission spectroscopy is used for the determination of plasma active particles (radicals, UV light) and plasma parameters during the fruit treatment. The infrared camera images confirm low and fully applicable heating of the treated surface that ensures no fruit quality changes. The detailed study shows that the efficiency of the microbial decontamination of selected fruits naturally contaminated by microorganisms is strongly dependent on the fruit surface shape. The decontamination of the rough strawberry surface seems inefficient using the current configuration, but for smooth berries promising results were obtained. Finally, antioxidant activity measurements demonstrate no changes due to plasma treatment. The results confirm that the MW surface wave sustained discharge is applicable to fruit surface decontamination.
Plasma-based technologies take an increasing place in the new conceptions of wastewater management as a promising tool for the treatment of persistent organic pollutants with low biodegradability. Plasma major advantage is the synergy of diverse active components with high oxidative action and additional benefits as disinfection of treated water. But the bactericidal effect of plasma can influence the treatment effectiveness when this technology is used in combination with biological methods for the removal of pollutants. The aim of this paper is to study the effect of non-thermal atmospheric plasma torch on key enzymes from phenol biodegradation pathways in Pseudomonas aureofaciens (chlororaphis) AP-9. The strain was isolated from contaminated soils and had a high potential for biodegradation of aromatic compounds. The used plasma source is surface-wave-sustained discharge operating at 2.45 GHz in argon produced by an electromagnetic wave launcher surfatron type. The enzyme activities of phenol 2-monooxygenase (P2MO), catechol 1,2-dioxygenase (C12DO), catechol 2,3-dioxygenase (C23DO), protocatechuate 3,4-dioxygenase (P34DO) and succinate dehydrogenase (SDH) were measured in control and after plasma treatment of 10, 30 and 60 s. At short-time treatment, the activities of intradiol dioxygenases increased with 26% and 59% for C12DO and P34DO, respectively. Other oxygenases and SDH were inhibited with 35% even at 10 s treatment. Longer treatment times had a clear negative effect but SDH kept the higher activity at 60 s treatment compared to the oxygenases. Our data suggest that plasma-based technologies are a useful approach for post-treatment of aryl-containing wastewater in order to increase the effectiveness of biological removal.
Cold atmospheric plasma (CAP) applications in various fields, such as biology, medicine and agriculture, have significantly grown during recent years. Many new types of plasma sources operating at atmospheric pressure in open air were developed. In order to use such plasmas for the treatment of biological systems, plasma properties should fulfil strong requirements. One of the most important is the prevention from heating damage. That is why in many cases, the post-discharge region is used for treatment, but the short living particles in the active discharge zone and reactions with them are missed in that case. We use the active region of surface-wave-sustained argon plasma for biological systems treatment. The previous investigations showed good bactericidal, virucidal, seeds germination and decontamination effects at a short treatment time, but the discharge conditions for bio-medical applications need specific adjustment. A detailed theoretical and experimental investigation of the plasma characteristics and their possible optimization in order to meet the requirements for bio-medical applications are presented in this paper. The length of the plasma torch, the temperature at the treatment sample position and the microwave radiation there are estimated and optimized by the appropriate choice of discharge tube size, argon flow rate and microwave power.
Cold atmospheric pressure plasma (CAP) sources have recently been proven to be an effective therapeutic source regarding wound healing. The most preferred and used plasma devices at this moment are the well-known dielectric barrier discharges (DBD) and free jet devices. In this work, we studied a low temperature plasma torch at atmospheric pressure sustained by a travelling electromagnetic wave excited by surfatron type wave launcher coupled to solid state microwave generator. This plasma source allows variation of discharge conditions: geometric parameters (discharge tube inner diameter and thickness), wave power and gas flow velocity which varies the main plasma parameters (length, gas temperature, concentration of charged particles and reactive species, UV and microwave radiation). Appropriate combination of the parameters lead to the low temperature plasma torch obtaining a gas temperature up to 30–37°C, suitable for in vivo treatment of BALB-C mouse models. The purpose of this research is to study the discharge conditions leading to acceleration of wound healing at short treatment times with relatively low gas flow and microwave power
We use a surface-wave sustained discharge (SWD) in argon at atmospheric pressure (using a plasma torch) in these experiments. The plasma torch is sustained using a 2.45-GHz electromagnetic wave with applied microwave powers of 13, 15, and 20 W. At these discharge conditions, the length of the plasma torch outside of the quartz tube is ~1-1.5 cm, and the gas plasma temperature does not exceed 40°C. This allows direct treatment of samples using the active zone of the discharge. In the cytotoxicity study, only two of the experimental settings achieve up to 50% survival of the cell monolayer after adding plasma-treated medium. Examining the effect of the plasma torch treatment media on herpes simplex virus-1 replication, we found that none of the applied experimental assays show significant protection on the cell monolayer. In a study of the virucidal action of a plasma-treated viral suspension diluted with sterile water at a ratio of 1:2 that was treated for 300 s at 13-W wave power, a decrease in the viral sample titer occurred unlike in the 1.67 log 10 control. Using optical emission spectroscopy, we found that OH intensity increases at the contact point between plasma and the water surface. Intensity of NO-γ also increases to the contact point with applied power. We also monitored the amount of peroxide radicals in plasma-treated water and nutrient medium in the presence of lucigenin.
During the past decade, cold plasma sources have gained much attention regarding sources operating at atmospheric pressure. The preferred plasma device to this point has been dielectric barrier discharges. In this work, we present well-known surface-wave-sustained microwave discharge operating at 2.45 GHz. This atmospheric pressure plasma torch can sustain low wall thickness, and dielectric permittivity) vary temperature and length of discharge. The purpose of this work is to precisely determine the working conditions at which this plasma source can be used in direct contact with biological objects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.