Pressure Argon Plasma Jet Research Articles

Experimental Studies on Physicochemical Parameters of Water Samples before and after Treatment with a Cold Atmospheric Plasma Jet and its Optical Characterization

Cold plasma-liquid interaction becomes a growing interdisciplinary area of research involving plasma physics, fluid science, and chemistry. Plasma-liquid interaction has gained more interest over the last many years due to its potential applications in different fields. Cold atmospheric plasma jet is an emerging technology for surface drinking water treatment to improve quality and surface modification that is chemical-free and eco-friendly. Cold plasma treatment of water samples results in changes in turbidity, pH, and conductivity and in the formation of reactive oxygen and nitrogen species (RONS). As a result, plasma-activated water has a different chemical composition than water and can serve as an alternative technique for microbial disinfection. CAPJ has been generated by a high voltage 5 kV and a high frequency 19.56 kHz power supply. The discharge has been characterized by an optical method. To characterize the cold atmospheric pressure argon plasma jet, discharge plume temperature, and electron rotational and vibrational temperature have been determined. Cold atmospheric argon plasma jet produced at atmospheric condition contains high energetic electrons, ions, UV radiation, reactive oxygen, and nitrogen species named as cold plasma which has a wide range of applications in the biomedical industry, as well as in water treatment. Nowadays, researches have been carried out on ozonation through plasma jet interaction with surface drinking water. In this paper, we compare the change in physical and chemical parameters of surface water used for drinking purposes. The significant change in the physical parameters such as pH, turbidity, and electrical conductivity was studied. In addition, the significant changes in the concentration and absorbance of nitrate, ferrous, and chromium ions with respect to treatment time were studied. Our results showed that plasma jet interaction with surface drinking water samples can be useful for the improvement of water quality and an indicator for which reactive species play an important role in plasma sterilization.

TiO2 Coatings Via Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition for Enhancing the UV-Resistant Properties of Transparent Plastics.

Herein, TiO2 coatings were deposited on photodegradable polymers for protection from UV irradiation using the atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique. Polymethylmethacrylate (PMMA) and polycarbonate (PC) substrates were coated with titanium tetraisopropoxide as the precursor in an open-air atmospheric-pressure nonequilibrium argon plasma jet. The AP-PECVD-derived TiO2 coatings exhibited good adhesion to PMMA and PC. The TiO2 coatings could shield more than 99% of UV light in the wavelength range of 200–300 nm, without affecting the transmittance of visible light. UV irradiation tests on polymer films demonstrated that the degradation rates of PMMA and PC were significantly reduced by one-tenth after they were coated with TiO2 films.

A Comparative Investigation on the Behaviors of Electrons in the Plasma Bullets in Atmospheric-Pressure Argon and Helium Plasma Jets

This article presents a comparative investigation on behaviors of electrons in the Ar and He plasma jets by means of the numerical simulation based on a typical needle-plate discharge configuration with positive applied pulsed voltage and a 1-D particle-in-cell Monte-Carlo collision (PIC-MCC) method. Emphasis is placed on the electrons in the bullet in the jets. In Ar, the bullet velocity is low and the electron density in the bullet is high, compared to He. In He, the energy spectrum of electrons (ESEs) in the bullet is of a low peak and a wide distribution, and the corresponding average electron energy is evidently high, contrary to Ar. The reason for this evident difference is mainly due to their different excitation energies and ionization energies as well as their different cross sections. In Ar and He, two electron densities N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> and Next in the bullet have been calculated. The former is the electron density in the bullet and the latter refers to a density of electrons in the bullet with energy above the lowest excitation threshold inducing the dissociative electron attachment (DEA) to water molecules. Consequently, not only N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> but also N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ext</sub> in Ar is higher than in He, meaning more generation of reactive species in aqueous solution via DEA mechanism. The ESEs in the bullet in Ar are more sensitive to the applied voltage amplitude than in He, thus in Ar, the increase in the applied voltage amplitude induces more evident increase in the average electron energy in the bullet than in He.

Risk Evaluation of EMT and Inflammation in Metastatic Pancreatic Cancer Cells Following Plasma Treatment

The requirements for new technologies to serve as anticancer agents go far beyond their toxicity potential. Novel applications also need to be safe on a molecular and patient level. In a broader sense, this also relates to cancer metastasis and inflammation. In a previous study, the toxicity of an atmospheric pressure argon plasma jet in four human pancreatic cancer cell lines was confirmed and plasma treatment did not promote metastasis in vitro and in ovo. Here, these results are extended by additional types of analysis and new models to validate and define on a molecular level the changes related to metastatic processes in pancreatic cancer cells following plasma treatment in vitro and in ovo. In solid tumors that were grown on the chorion-allantois membrane of fertilized chicken eggs (TUM-CAM), plasma treatment induced modest to profound apoptosis in the tissues. This, however, was not associated with a change in the expression levels of adhesion molecules, as shown using immunofluorescence of ultrathin tissue sections. Culturing of the cells detached from these solid tumors for 6d revealed a similar or smaller total growth area and expression of ZEB1, a transcription factor associated with cancer metastasis, in the plasma-treated pancreatic cancer tissues. Analysis of in vitro and in ovo supernatants of 13 different cytokines and chemokines revealed cell line-specific effects of the plasma treatment but a noticeable increase of, e.g., growth-promoting interleukin 10 was not observed. Moreover, markers of epithelial-to-mesenchymal transition (EMT), a metastasis-promoting cellular program, were investigated. Plasma-treated pancreatic cancer cells did not present an EMT-profile. Finally, a realistic 3D tumor spheroid co-culture model with pancreatic stellate cells was employed, and the invasive properties in a gel-like cellular matrix were investigated. Tumor outgrowth and spread was similar or decreased in the plasma conditions. Altogether, these results provide valuable insights into the effect of plasma treatment on metastasis-related properties of cancer cells and did not suggest EMT-promoting effects of this novel cancer therapy.

Generation of a large-scale uniform plasma plume through the interactions between a pair of atmospheric pressure argon plasma jets

In this Letter, a uniform air plasma plume with a fairly large scale is generated downstream of an air flow through interactions between a pair of argon plasma jets excited by a direct current power supply. With increasing power voltage, two separated plumes are first generated downstream of the pair of jets, which transit to the uniform planar plume with a fairly large scale. The planar plume elongates with the increasing air flow rate or power voltage. Moreover, the temperature of the planar plume is comparatively low with a maximum of about 80 °C, which is symmetrically distributed perpendicular to the pair of jets. For the separated plumes, discharge current is intermittently pulsed under a time-invariant gap voltage. However, both gap voltage and discharge current are periodically pulsed for the planar plume. High-speed video images reveal that the planar plasma plume stems from two discrete plumes flushing out of the pair of jets, which are soon merged together by a cathode-directed streamer due to interactions between them, leading to the generation of an arc-shaped filament. Due to the air flow, the arc-shaped filament keeps moving away from the jet vicinity until it quenches at last, which belongs to a glow discharge regime. In addition, surface modification of polyethylene terephthalate (PET) is performed with our planar plasma plume, which reveals that the hydrophilicity of the PET surface can be improved greatly.

Experimental investigation of a ns-pulsed argon plasma jet for the fast desorption of weakly volatile organic compounds deposited on glass substrates at variable electric potential

A ns-pulsed argon atmospheric pressure plasma jet (APPJ) was studied for the fast desorption of weakly volatile organic molecules (bibenzyl) deposited on glass substrates at variable electric potential (floating-potential or grounded). The experiments focused particularly on thin resistant bibenzyl films (a large thick bibenzyl deposit was also studied), which are more difficult to be desorbed when using a substrate at a floating-potential. The APPJ was probed by means of high-resolution laser absorption spectroscopy to map the Ar(1s5) metastable absolute density (spatially and temporally resolved) at the close vicinity of the glass plate where bibenzyl was deposited. Furthermore, the electrical, optical and thermal features of the APPJ were investigated systematically. In this way, the plasma desorption efficacy on thin resistant bibenzyl deposits was evaluated for the envisaged application, by varying the exposure time of the molecules to the APPJ (texp, from 10 s up to 180 s). The obtained results confirm the relatively low desorption efficacy in the case of a floating-potential substrate, which improves to some extent with increasing texp. However, when the substrate is grounded, the effect of the plasma becomes much more significant (i.e. much higher desorption efficacy). Besides, contrary to the case of a floating-potential substrate, an almost complete desorption of bibenzyl is achieved for texp = 180 s. Similar effects of the APPJ were recorded on a thick bibenzyl deposit, validating the previous results. For both operating conditions (floating-potential and grounded substrate), the plasma action should be due to the production close to the glass surface of relatively high densities of Ar(1s5) (up to 2 1013 cm−3) and of oxidative species, such as atomic oxygen, hydroxyl radical and ozone. Thermal effects might play a synergistic role only when the substrate is grounded, since relatively high gas and glass-surface temperatures (>60 °C) are reached only in this case. The present results are of interest for public-security applications related to the fast detection of resistant prohibited substances, such as narcotics and explosives.

A Numerical Investigation on the Behavior of Electrons in the Bullet in the Atmospheric- Pressure Argon Plasma Jet

Electrons are generated abundantly in the plasma jet and play an active role in the mass transfer of reactive species in the aqueous solution in plasma medicine. Such an importance requires knowledge of the behavior of electrons in the plasma jet. The objective of this work is to understand the electron behaviors in the bullet in the plasma jet, including the angle spectrum of electrons (ASEs) and the related energy spectrum, so as to have an insight into those electrons which most probably interact with the target. The numerical modeling based on a needle–plate discharge configuration in conjunction with a 1-D Particle-in-Cell Monte-Carlo Collision (PIC-MCC) simulation method was used to achieve this task. The scattering angle of electron in the bullet is described using the angle between the electron scattering direction and the bullet propagation direction. The ASE in the bullet is close to a sinusoidal distribution. As the bullet propagates, the temporal evolution of ASE indicates that relatively more electrons in the bullet are scattered into the angle range below 90°, but at any moment when the propagating bullet is close to the target, ASE in the bullet generally remains unchanged. In addition, relatively less electrons in the bullet are scattered into the angle range below 90° due to the increase of the applied voltage amplitude. For the considered voltage amplitudes below 7 kV, the number of electrons in the angle range below 90° is within 47% of electrons in the bullet and, in these electrons, the proportion of non-subionization electrons reaches about 12%. These results may be taken into consideration in investigating the mass transfer of reactive species in plasma medicine.

Anticancer Effects of Plasma-Activated Medium Produced by a Microwave-Excited Atmospheric Pressure Argon Plasma Jet.

Cold atmospheric plasma (CAP) has been reported to have strong anticancer effects in vitro and in vivo. CAP has been known to induce apoptosis in most cancer cells by treatment to cells using direct and indirect treatment methods. There are many reports of apoptosis pathways induced by CAP, but for indirect treatment, there is still a lack of fundamental research on how CAP can cause apoptosis in cancer cells. In this study, we applied an indirect treatment method to determine how CAP can induce cancer cell death. First, plasma-activated medium (PAM) was produced by a 2.45 GHz microwave-excited atmospheric pressure plasma jet (ME-APPJ). Next, the amounts of various reactive species in the PAM were estimated using colorimetric methods. The concentration of NO2– and H2O2 in PAM cultured with cancer cells was measured, and intracellular reactive oxidative stress (ROS) changes were observed using flow cytometry. When PAM was incubated with A549 lung cancer cells, there was little change in NO2– concentration, but the concentration of H2O2 gradually decreased after 30 min. While the intracellular ROS of A549 cells was rapidly increased at 2 hours, there was no significant change in that of PAM-treated normal cells. Furthermore, PAM had a significant cytotoxic effect on A549 cells but had little effect on normal cell viability. In addition, using flow cytometry, we confirmed that apoptosis of A549 cells occurred following flow cytometry and western blot analysis. These results suggest that among various reactive species produced by PAM, hydrogen peroxide plays a key role in inducing cancer cell apoptosis.

Experimental Study of Cold Atmospheric Pressure Plasma Jet and Its Application in the Surface Modification of Polypropylene

The cold plasma technology is gaining popularity as one of the most effective tools for a wide range of applications. Cold atmospheric pressure plasma jet (CAPPJ) has attracted considerable attention in recent times for materials processing such as surface modification and biomedical applications. The cold atmospheric pressure plasma jet sustained in pure argon has been used here to modify the surface properties of polypropylene. CAPPJ has been generated by a high voltage power supply 5 kV at an operating frequency of 20 kHz. This paper reports the diagnostics of CAPPJ in argon environment by electrical and optical methods and its application in the surface modification of polypropylene (PP). The surface properties of the untreated and plasma-treated PP samples were characterized by contact angle measurements, surface free energy determination, scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Most of the previous work has used RF power supply which is more expensive compared to the power supply used in the present study. The plasma jet is designed with locally available materials and can be used for continuous treatment for long time. We have successfully developed a plasma device that is able to generate a non-equilibrium atmospheric pressure argon plasma jet of low temperature. Therefore, a cost-effective system of generating a plasma jet at atmospheric pressure with potential applications in materials processing and biomedical research has been developed.

Application of Atmospheric Pressure Argon Plasma Jet (APAPJ) in Biomedical Science and Engineering

In this paper, we demonstrated the application of atmospheric pressure argon plasma jet (APAPJ) in biomedical science such as cancer therapy and biomedical engineering such as surface modification of polystyrene Petri dishes for animal cell culture. We observed that APAPJ, when exposed to breast cancer cell line (MDA-MB-231) for 60 seconds at a distance of ~ 2.5 cm, reduced the cancer cells by 57%. This reduction in cancer cell concentration demonstrated the cancer-killing property of APAPJ. Further optimization of APAPJ's various operational parameters and in-depth biochemical study is required to figure out the mechanism responsible for killing cancer cells. Also, we investigated cell adhesion and proliferation due to APAPJ treatment by Crystal Violet (CV) staining and MTT Assay. We observed that APAPJ treatment of polystyrene Petri dishes for 60 - 240 s at a distance of ~ 3.5 cm exhibited enhancement in adhesion of breast cancer cell line (MDA-MB-231). We also demonstrated the increase in hydrophilicity by a reduction in contact angle to 30.3°±3 after 240 seconds of APAPJ treatment of polystyrene samples. The hydrophilicity of the substrate has proven to enhance cell adhesion. Consequently, APAPJ could be employed as a simple, inexpensive and environmentally friendly method for surface modification of polystyrene plates for animal cell culture.

Modelling of turbulent reacting flow for a cold atmospheric pressure argon plasma jet

A two-dimensional, axisymmetric model of turbulent reacting flow for a cold atmospheric pressure argon plasma jet has been developed. The model is formulated within the framework of boundary-layer theory and allows to study the transport and chemical processes in the jet with low computational effort. The generation of primary reactive gas species is described using a local zero-dimensional reaction kinetics model. The proposed modelling approach is validated against available experimental data. The computations are performed for a turbulent cold plasma jet operated in argon with admixtures of oxygen, air and water. The effect of a shielding gas on the transport and chemical processes is discussed. The modelling results are compared with the results of quantitative schlieren diagnostics (for Ar), molecular-beam mass spectrometry (for Ar, N2, O2), laser-induced fluorescence (for NO), two-photon absorption laser-induced fluorescence (for O), ultraviolet absorption (for O3) and cavity ring-down (for HO2) spectroscopy measurements. It is shown that turbulent diffusion across the jet is an important factor influencing the behaviour of reactive species that are of interest for practical applications.

Combination Treatment with Cold Physical Plasma and Pulsed Electric Fields Augments ROS Production and Cytotoxicity in Lymphoma.

New approaches in oncotherapy rely on the combination of different treatments to enhance the efficacy of established monotherapies. Pulsed electric fields (PEFs) are an established method (electrochemotherapy) for enhancing cellular drug uptake while cold physical plasma is an emerging and promising anticancer technology. This study aimed to combine both technologies to elucidate their cytotoxic potential as well as the underlying mechanisms of the effects observed. An electric field generator (0.9–1.0 kV/cm and 100-μs pulse duration) and an atmospheric pressure argon plasma jet were employed for the treatment of lymphoma cell lines as a model system. PEF but not plasma treatment induced cell membrane permeabilization. Additive cytotoxicity was observed for the metabolic activity and viability of the cells while the sequence of treatment in the combination played only a minor role. Intriguingly, a parallel combination was more effective compared to a 15-min pause between both treatment regimens. A combination effect was also found for lipid peroxidation; however, none could be observed in the cytosolic and mitochondrial reactive oxygen species (ROS) production. The supplementation with either antioxidant, a pan-caspase-inhibitor or a ferroptosis inhibitor, all partially rescued lymphoma cells from terminal cell death, which contributes to the mechanistic understanding of this combination treatment.

Energy Spectrum of Electrons in the Plasma Bullet and Its Applied Voltage Effect in Atmospheric-Pressure Argon Plasma Jets

This article presents a numerical investigation on the energy spectrum of electrons (ESE) in an atmospheric-pressure argon plasma jet, based on a typical needle-plate discharge system with a positive applied voltage and a 1-D particle-in-cell Monte Carlo collision model. The spatiotemporal evolution characteristics of the ESEs in the three characteristic areas have been revealed. The three characteristic areas refer to the plasma bullet (the bullet), the dark channel behind the bullet, and the dim area in front of the bullet. The effects of the applied voltage amplitude on the ESEs have also been shown. As the bullet propagates, the ESEs in the bullet and the dark channel present an increasingly high peak and a gradually narrowing distribution, showing a decrease in average energy $E_{\mathrm {ave}}$ of electrons, and in the dim area, the evolution of the ESE is opposite to that in the bullet. In contrast, the bullet has a substantial contribution to energetic electrons above the excitation threshold of argon, which shows that in applications of the plasma jet in biomedicine, the particles transporting into the aqueous solutions on the surface of living tissues may contain substantial non-subionization electrons. In the three characteristic areas, ESEs present an increasingly low peak and an increasingly wide distribution with the increase in the applied voltage amplitude, meaning an increasing $E_{\mathrm {ave}}$ . Compared to the other two areas, $E_{\mathrm {ave}}$ in the bullet is evidently high. In particular, a high applied voltage can induce a remarkable increase of high-energy electrons in the bullet, reaching a ratio of about 26% much higher than that in the other areas, under the applied voltage of 7 kV. This is of significance for plasma medicine.

The effect of a second grounded electrode on the atmospheric pressure argon plasma jet

Cold atmospheric pressure plasma jet has attracted a great interest of researchers engaged in different areas due to its wide range of applications. In this article, the effect of adding a second grounded electrode (SGE) to the two electrodes plasma jet system was investigated. The jets system consisted of a quartz tube surrounded by two copper strips, which were separated by 40 mm. The SGE was placed below the jet nozzle by 2 mm and 5 mm from its axial. The jet characteristics with and without the SGE were investigated using plasma images, voltage-current waveforms, and emission spectra. Two current pulses per each half a cycle were measured when the SGE was used while one pulse was measured without using it. The second current pulse was much longer than the first one. Argon emission spectra were the most intense lines among all other plasma species even for the measurement out of the flow stream. The OH• emission spectra were higher in the discharge zone than those outside the discharge zone. The presence of the SGE enhanced the emission spectra for all the investigated positions above and in front of the SGE. The transition from laminar to turbulent mode was observed at lower flow rate value without using the SGE and a significant decrease in jet length was detected at 3.5 slpm with and without using the SGE. This system is scalable by using multi-SGE to form a large volume plasma, which is strongly required for biomedical and industrial applications.

A streamer behavior evolution during an applied voltage cycle in helium and argon atmospheric pressure plasma jets fed by DBD

The study describes the behavior of plasma streamer discharges in helium and argon atmospheric pressure plasma jets fed by dielectric barrier discharge with the specific AC voltage waveform, which has hundred-kHz oscillations deviated from the zero level. The equivalent electrical and gas feeding conditions for producing both helium and argon jets have been provided. The plasma jet in helium is shown to have a diffusive structure and is formed by guided ionization waves, whereas an argon plasma jet is formed by numerous filaments which can have several branches on their ends. Repetitive stepwise plasma bullet formation has been observed in He plasma jet, whereas random and stochastic branching of the streamer has been recorded in Ar plasma jet. Both types of streamers have an approximately equal maximum of their length but significantly differ with the lifetime: they exist for about 1 and almost 8 μs in the argon and helium plasma jets, correspondingly.

Evaluation of influence of cold atmospheric pressure argon plasma operating parameters on degradation of aqueous solution of Reactive Blue 198 (RB-198)

The intention of this work is to remove Reactive Blue 198 (RB-198) dye components from simulated water solution using cold atmospheric pressure argon plasma jet. Aqueous solutions of RB-198 dye were treated as a function of various operating parameters such as applied potential, reaction time and distance between the plasma jet and surface of the liquid. The efficiency of the degradation of RB-198 molecules was explored by means of UV-Vis spectroscopy. The reactive species involved during the treatment process were examined by optical emission spectra (OES). The present hydroxyl radicals (OH• radical) and hydrogen peroxide (H2O2) in the plasma-treated aqueous dye solutions were investigated using various spectroscopic techniques. The other parameters such as total organic carbon (TOC), conductivity and pH were also reviewed. The toxicity of plasma-treated RB-198 solution was finally studied by diffusion bacterial analysis and by tracking seed germination processes. The results show that a higher degradation percentage of 99.27% was acquired for the RB-198 treated at higher reaction time and applied potential, and shorter distance between the plasma jet and water surface. This may be due to the formation of various reactive oxygen (OH• radical, atomic oxygen (O) and H2O2) and nitrogen species (nitric oxide (NO) radicals and N2 second positive system (N2 SPS)) during the processes as confirmed by OES analysis and other spectroscopy analysis. TOC (17.7% – 81.8%) and pH (7.5 – 3.4) values of the plasma-treated RB-198 decreased significantly with respect to various operation parameters, which indicates the decomposition of RB-198 molecules in the aqueous solution. Moreover, the conductivity of plasma-treated RB-198 aqueous solutions was found to have increased linearly during the plasma treatment due to the formation of various ionic species in aqueous solution. The toxicity analysis clearly exhibits the non-toxic behavior of plasma-treated RB-198 aqueous solution towards the bacterial growth and germination of seeds.

Enhanced Microbial Decontamination Using Non-thermal Low Pressure Argon Plasma Jet.

Atmospheric pressure plasma jet (APPJ) gained great interest due to its effectiveness as selective non-lethal technique with low operational costs. In this study, argon APPJ system was designed and the generated cold plasma was applied in disinfection of microbial cells. Argon APPJ was generated by blowing argon through capillary metallic tube inserted in alumina and powered by 8-25 kHz sinusoidal voltage waveform. The plasma applied in inactivation of microbes by direct exposure of cell suspension, approximately 10 mm below jet nozzle, for different intervals. Interference of organics in exposure medium, on lethal activity of plasma was investigated. APPJ jet induced high levels of reactive oxygen (ROS) and nitrogen species (RNS). Jet length increased with applied voltage and flow rate in laminar mode, but decreased with flow rate in turbulent mode. Percent reduction in living cell count was 98.3 and 94.1%, for E. coli and S. aureus suspended in water after 30s of exposure, respectively, with 2.7- and 2-folds increase in plasma lethal activity, as compared with LB broth medium. D-values (Decimal Reduction Time) were increased from 34-333, 37-476 and 139-385 s for E. coli, S. aureus and C. albicans in water and complex liquid organic media, respectively. Designed argon APPJ system can be used in disinfection of different microbes. Plasma antimicrobial activity drastically decreased in presence of organic matter. The generated plasma can be promising approach for treatment of diseases, especially caused by antibiotic-resistant pathogens.

Cell viability and measurement of reactive species in gas- and liquid-phase exposed by a microwave-excited atmospheric pressure argon plasma jet

A microwave-excited atmospheric pressure plasma jet (ME-APPJ) was generated utilizing coaxial transmission line resonators with the resonance frequency of 788 MHz. We investigated the effects of the operating parameters such as input power and gas flow rate on the electron excitation temperature and electron density using optical emission spectroscopy. The amounts of various reactive species in the plasma-activated media (PAM) exposed by the ME-APPJ were estimated using colorimetric methods. The PAM was applied to A549 cultured cells and subsequently incubated for a given duration. The concentrations of NO2− and H2O2 in the PAM incubating A549 cells were monitored until 24 h. The reduced cell viability rate was observed on A549 cells incubated in the PAM. The concentrations of NO2− and H2O2 and the viability of A549 cells depended on the operating conditions of ME-APPJ. The cell viability rate exhibited a decrease with increasing power and decreasing gas flow rate. Correlation between the concentrations of gaseous reactive species in the plasma and in the PAM and the cell viability is discussed.

Surface analysis and characterization of atmospheric pressure argon plasma jet treated methyl methacrylate monomer films

An atmospheric pressure plasma jet setup was used to treat methyl methacrylate monomer, using argon plasma at varying treatment times. Treated samples were then poured onto glass slides and allowed to dry to form a thin-film. Surface characterization was performed using wettability analysis, AFM, XPS and FTIR. Treated samples, ranging from 10–25 min of treatment time all exhibited increased hydrophobic property compared to plain glass and untreated monomer film on glass slide samples. The 20 min treated sample exhibited the highest hydrophobic property with an average contact angle of 92.40°. The upper error bound contact angle value for this parameter is nearly as high as that of commercial MMA. XPS analysis showed a decrease in the presence of O1s peaks for the 20 min treated sample as compared to the untreated control. This supports wettability data, as the presence of polar oxygen bonds would lead to more hydrophilic surfaces.

Decolorization of Amaranth aqueous solution by atmospheric-pressure plasma jet irradiation

The decolorization of Amaranth aqueous solution by irradiation with an atmospheric-pressure plasma jet was examined by absorbance spectrum measurement and nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyzes. An atmospheric-pressure argon (Ar) plasma jet was generated at a frequency of 10 kHz with an applied voltage of 10 kV and an Ar gas flow rate of 10 l min−1. When 10 ml of 100 mg l−1 Amaranth aqueous solution was irradiated with this plasma jet, the red solution gradually became lighter with increasing irradiation time and was almost completely decolorized after 70 min of irradiation. The results of NMR and MS analyzes indicated that the decolorization was caused by the destruction of the azo bond in the Amaranth molecules.