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An experimental study was conducted to test the effect of changing the frequency of a 10 kV alternating voltage source on the properties of a plasma jet. Optical emission spectra of the plasma were recorded and analyzed. In plasma physics, the electron temperature and density are key parameters. These were determined using a Boltzmann plot and the Stark broadening of the argon line at 763.153 nm, respectively. As the frequency of the alternating voltage source was increased from 10 to 30 kHz (in increments of 5 kHz), the electron temperature increased from 0.995 to 1.357 eV and the electron density rose from 12.027 × 1017 to 12.838 × 1017 cm−3. A strong correlation between the plasma parameters and the frequency of the alternating voltage source was evident. Measurements were also taken on the length of the plasma torch, which was found to grow from 0.041 to 0.051 m as the frequency of the supply voltages was increased. Furthermore, the effect of plasma on the temperature of a silicon target was investigated for a range of frequencies of the supply voltage. It was observed that a slight increase in temperature occurred with increasing frequency, at a constant argon gas flow rate. The effect of plasma jetting on a silicon target was studied at a fixed voltage frequency and a variable gas flow rate. Only a small increase in target temperature was observed. This ensures that no damage or unwanted effects occur on the material being processed. [ABSTRACT FROM AUTHOR]

The paper investigates the properties of polymer composite films comprised of chitosan and 1% hydroxyapatite nanoparticles following treatment with a plasma jet, using argon as the working gas. Hydroxyapatite is typically added to chitosan to enhance its mechanical properties. The study found that plasma jet treatment increases both the mechanical strength and elastic modulus of the films. Additionally, the treatment reduces the water contact angle (WCA) from 70° to 26°, indicating improved hydrophilicity от. FTIR spectroscopy results confirm that no new chemical bonds are formed during the treatment. Scanning electron microscopy (SEM) images reveal the removal of amorphous regions in the polymer film post-treatment. This modification enhances the adhesion of human fetal mesenchymal stem cells (FetMSCs) to the film, suggesting that these treated films could be suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

The modulation of surface properties of Ti3C2Tx plays a crucial role in its diverse applications across various fields. However, a straightforward and reliable technique for controlling its surface functional groups remains elusive. In this study, we achieved controlled modification of Ti3C2Tx surface functional groups using atmospheric‐pressure cold plasma. We evaluated the plasma generation characteristics and found that the gas parameters could influence the discharge power and lead to different gas temperatures with the same voltage. Spectral analysis confirmed the presence of numerous reactive species in the plasma, facilitating the breaking and recombination of chemical bonds of functional groups on the Ti3C2Tx surface. The interaction between the plasma jet and Ti3C2Tx film revealed that the semiconductor properties of the Ti3C2Tx film limit the plasma diffusion area, while N2 doping and increased gas flow rates respectively reduce and enlarge the coverage area of cold plasma. A brief one‐minute cold plasma treatment induced a slight etching effect on the Ti3C2Tx film surface, effectively altering the ‐O and ‐F functional groups. However, it is noteworthy that excessive cold plasma treatment in the air may result in partial oxidation of Ti3C2Tx, necessitating the use of custom gas environments in further applications. This research provides valuable insights into surface modification techniques for Ti3C2Tx with potential implications in a wide range of applications. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of atmospheric pressure plasma jet (APPJ) treatment on the surface characteristics and bond strength of zirconia and lithium disilicate ceramics for CAD-on restorations. A total of 70 cylindrical-shaped specimens of lithium disilicate and 70 disc-shaped specimens of Y-TZP zirconia were machined, thermally processed, surface-treated, and then resin-bonded. The specimens were grouped according to the following surface treatments: no surface treatment, sandblasting, plasma, sandblasting followed by plasma, sandblasting followed by universal adhesive, plasma followed by universal adhesive, and sandblasting and plasma treatment followed by universal adhesive. The treated surfaces were subjected to a wettability assessment via contact angle measurement and a topography assessment using scanning electron microscopy (SEM). The cemented assembly was subjected to shear bond strength testing with a universal testing machine, and the results were imported to SPSS 23.0 for statistical analysis. The results show that APPJ treatment induced a significantly low contact angle for both ceramics with no surface alteration upon scanning. Moreover, APPJ treatment produced a bonded assembly with a shear bond strength comparable to sandblasting. In conclusion, APPJ treatment should be considered an efficient surface treatment with a non-destructive nature that surpasses sandblasting with the provision of a high shear bond strength between CAD-on ceramics. [ABSTRACT FROM AUTHOR]

Atmospheric plasma jets generated from air or nitrogen using commercial sources with relatively high energy densities are commonly used for industrial applications related to surface treatments, especially to increase the wettability of polymers or to deposit thin films. The heat fluxes to which the substrates are subjected are typically in the order of 100–300 W/cm2, depending on the treatment conditions. The temperature rise in the treated polymer substrates can have critical consequences, such as a change in the surface crystallinity or even the surface degradation of the materials. In this work, we report the phase transitions of two semicrystalline industrial-grade polymer resins reinforced with glass fibers, namely polyphenylene sulfide (PPS) and polyphthalamide (PPA), subjected to plasma treatments, as well as the modeling of the associated heat transfer phenomena using COMSOL Multiphysics. Depending on the treatment time, the surface of PPS becomes more amorphous, while PPA becomes more crystalline. These results show that the thermal history of the materials must be considered when implementing surface engineering by this type of plasma discharge. [ABSTRACT FROM AUTHOR]

In this work, zinc nanoparticles were prepared using the low-temperature plasma method at different times 3 min, 5 min, 7 min, 9 min, where the initial reactions of zinc lead to the formation of nanoparticles. The metal interacts with the ionized plasma under different conditions and may turn into an oxide such as exposing the sample to air and raising the temperature of the solution a few degrees as a result of high voltage and within a certain range. The atmospheric pressure plasma system acts as the cathode, while the zinc metal strip acts as the anode. A series of techniques were used, including the use of X-ray diffraction (XRD), ultraviolet-visible spectroscopy and scanning electron microscopy (FESEM). The X-ray diffraction results showed that the samples have polycrystalline structures with hexagonal and cubic structures with a time difference, and the X-ray diffraction results showed the conversion of zinc particles into zinc oxides. FESEM images reveal particle size and shape. The ZnO nanoparticles prepared by the mentioned method seem to form different nanoshapes such as starfish and mushroom nanoparticles. The UV-visible results showed that the samples had an energy gap of about 3.4 eV at a time of 3 min, and this value decreases with increasing reaction time. The appearance of zinc oxides increases gradually with the passage of time. These results provide credibility for the fabrication of ZnO nanostructures for use in future gas sensing applications, despite the inhomogeneity of particle size among ZnO particles, the sensor was also fabricated to detect nitrogen gas (NH3) with different concentrations (17.25 ppm, 46.38 ppm, 78.58 ppm). at room temperature. The ZnO sample showed the highest sensitivity (88.1%) at 7 min. The sensitivity showed different results and increased with reaction time and gas concentration. However, response and recovery time are moderate and decrease as reaction time increases. [ABSTRACT FROM AUTHOR]

In order to produce cold plasma at atmospheric pressure, a multi-channel RF, of (1, 2, 3, and 4 MHz) frequencies, plasma jet system is developed using argon as the working gas. This system consists of two parts, a multi-channel power supply (of a power of 100 W) and a plasma jet. A strong electric field is created that ionizes and excites argon ions. The I-V characteristics of the system and the electron temperature and density for different powers (20, 50, 70, and 80 W), gas flow rates (10, 20, 30, and 40 sccm) (standard centimeter cubic per minute) at different frequencies (1, 2, 3, and 4 MHz) are studied, using the optical emission spectroscopy method. This system can be used in medical applications and material treatment with high efficiency. [ABSTRACT FROM AUTHOR]

Cold physical plasma, a partially ionized gas, has been shown to be effective in treating chronic wounds and cancer. However, there is limited research on plasma exposure of leukemia cell lines, such as chronic lymphocytic leukemia (CLL) and cytotoxic CD8+ T cells. To investigate the potential proimmunogenic effects of plasma‐derived reactive oxygen species, cytotoxic T cells were isolated from CLL patients and healthy volunteers. Extensive cold plasma treatment reduced T‐cell metabolic activity and viability in both diseased and healthy groups. Plasma treatment of cocultures, but not CD8+ T‐cell monocultures, spurred cytotoxic T‐cell proliferation, possibly due to plasma‐enhanced CLL antigen display and plasma‐mediated modulation of immunoregulatory surface molecules. Further studies are needed to understand the mechanisms and clinical relevance of these findings. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of atmospheric pressure plasma jet (APPJ) treatment on the surface characteristics and bond strength of zirconia and lithium disilicate ceramics for CAD-on restorations. A total of 70 cylindrical-shaped specimens of lithium disilicate and 70 disc-shaped specimens of Y-TZP zirconia were machined, thermally processed, surface-treated, and then resin-bonded. The specimens were grouped according to the following surface treatments: no surface treatment, sandblasting, plasma, sandblasting followed by plasma, sandblasting followed by universal adhesive, plasma followed by universal adhesive, and sandblasting and plasma treatment followed by universal adhesive. The treated surfaces were subjected to a wettability assessment via contact angle measurement and a topography assessment using scanning electron microscopy (SEM). The cemented assembly was subjected to shear bond strength testing with a universal testing machine, and the results were imported to SPSS 23.0 for statistical analysis. The results show that APPJ treatment induced a significantly low contact angle for both ceramics with no surface alteration upon scanning. Moreover, APPJ treatment produced a bonded assembly with a shear bond strength comparable to sandblasting. In conclusion, APPJ treatment should be considered an efficient surface treatment with a non-destructive nature that surpasses sandblasting with the provision of a high shear bond strength between CAD-on ceramics.

This work presents a numerical analysis by zero-dimensional global model of the influence of electron temperature and concentration on production of OH and NO for helium plasma jet propagating in the atmosphere of humid air. The calculations are done for the constant electron temperatures (1–4 eV) and concentrations (1010 cm−3 to 1014 cm−3). The mole fractions of air and water vapor vary from 100 to 10,000 ppm. The presented analysis reveals that at low electron temperature and H2O contents, the dissociative electron attachment to O2 dominates over attachment to H2O in production of OH. At higher amount, H2O modifies the high-energy tail of electron distribution function and increases rate coefficients for electron impact processes. Dissociative electron attachment to H2O dominates in the production of OH at 1 eV and remains important at higher energies when processes with O(1D), O(1S), O2(1∆) produce OH. Impact dissociation of H2O dominates over the dissociative attachment at 3 and 4 eV. NO comes mainly from air effluent in the plasma and O + NO2 at 100 ppm of H2O. Above 2 eV, the conversion process between OH and NO dominates in NO production at higher amount of H2O. Regarding dependencies on electron concentration, at low electron temperatures, electron distribution function is affected only at 1014 cm−3. But in the case of higher temperature, electron concentration and water vapor have negligible influence. The best agreement with measured data is obtained for electron concentration 1010 cm−3 and at temperature of 2 eV for OH and 1012 cm−3 and 3 eV for NO.

This research aim is to activate water using a plasma jet that works with argon gas and to study the effect of the plasma on the physicochemical properties of the water. The plasma consists of a power supply capable of supplying a high alternating voltage of up to 12 kV in the form of a sinusoidal wave with a frequency of 20 kHz. The temperature of the produced plasma (Te) was (1.028) eV, and its electron density (ne) was (4.392×1017) cm-3 at a flow rate of 1L/min. The physicochemical properties of the water are determined by determining the concentration of each of NO2, NO3, and H2O2, the pH of the water, and the water temperature during exposure to the plasma. The effect of storage time on the properties of the activated water is determined after 48 hours of exposure to plasma. The RONS species were measured using kits purchased from USA (Bartovation) Company manufactured for this purpose. The pH was measured with a pH meter, and the working gas temperature was remotely measured with an IR thermometer. The concentration of the three active species increases with exposure time, but the active species NO2 concentration decreases to zero at an exposure time of 120 minutes. The concentrations of the three components decrease with the decrease in the flow rate. The pH decreases with the exposure time until it reaches 2, and the temperature increases until it reaches 35oC. The concentration of NO3 increases with the increase of the water storage time. In the case of H2O2, the concentration increases slightly, then after 10 hours it begins to decrease exponentially, reaching a value close to zero after the passage of 48 hours. For NO2, its concentration begins to decrease exponentially from the start of storage and reaches a concentration close to zero after 48 hours of storage. The pH increases with the storage time, and the water reaches its natural state with a pH of 7 after 48 hours of storage. From this, it is concluded that the best storage time for PAW is ten minutes after the end of the activation process, and also that the activation time should be short, but not exceeding ten minutes. [ABSTRACT FROM AUTHOR]

The article considers combined methods of restoration and hardening of massive metalworking and tillage tools, which involve both induction hardening or surfacing and plasma surface treatment. The methods increase not only the hardness and wear resistance of the tool material, but also its toughness and crack resistance, which is not achieved by traditional methods of surface hardening. [ABSTRACT FROM AUTHOR]

An extensive study on the green auroral emission characterization is presented based on a single dielectric barrier discharge geometry argon plasma jet driven by a kHz sine voltage. The plasma was generated by using 99.999% pure argon and the observed 557.7 nm green line resulted from the excited O(1S) state. An optical emission spectroscopy method using line ratios of argon was used to obtain the electron density and electron temperature under different conditions in the downstream region. The characteristics of discharge and green emission with variations in interelectrode distance, applied voltage (power) and flow rate are discussed. The spatially diffuse distribution of O(1S), owing to its long lifetime, is shown by the short exposure imaging. Two discharge regimes are presented, accompanied by two distinct branches of the green emission intensity, with a clear conclusion that the 557.7 nm emission is favored in the low electron temperature environment. In this work, the intense and diffuse green plume only forms when the downstream electron density is approximately lower than 1 × 1014 cm−3 and the electron temperature is lower than 1.1 eV. By charging the two electrodes in two opposite ways, it is shown that the green emission from oxygen is favored in the case where the electric field and the electron drift are not continuous. [ABSTRACT FROM AUTHOR]

The bactericidal components of air plasma jets generated by a direct-current glow discharge and a dielectric barrier discharge were studied using IR and UV absorption spectroscopy. The mole fractions of bactericidal components with an absorption spectrum band structure were determined by selecting a mole fraction value in the calculated spectrum that ensured correlation with the experimental spectrum. The spectra were calculated using the HITRAN spectral database and the Specair 3.0 program. The error in the mole fractions due to violation of the Bouguer–Lambert–Beer law when using absorption coefficients convoluted with the instrument function was determined. The mole fractions of bactericidal components with a continuous absorption spectrum were calculated using the Bouguer–Lambert–Beer law in a standard way. IR and UV absorption spectroscopy were shown to enable determination of the mole fractions for the full set of bactericidal components in air plasma jets of glow and barrier discharges. [ABSTRACT FROM AUTHOR]

This research scrutinizes the impact of external magnetic field strength variations on plasma jet parameters to enhance its performance and flexibility. Plasma jets are widely used for their high thermal and kinetic energy in both medical and industrial fields. The study employs optical emission spectroscopy to measure electron temperature, electron density, and plasma frequency in a plasma jet subjected to varying magnetic field strengths (25, 50, 100, 150, and 250 mT). The results indicate that a stronger magnetic field results in higher electron temperature (1.485 to 1.991 eV), electron density (5.405 × 1017 to 7.095 × 1017), and plasma frequency 7.382 × 1012 to 8.253 × 1012 Hz. As well as the research investigates the influence of gas flow rate on gas temperature in the plasma jet. It is observed that gas temperature gradually drops with a growth in the flow rate of argon gas. The voltage and current waves have a sinusoidal waveform without elevation lines and with decaying waveforms. The existence of a strong magnetic field generates magnetohydrodynamic instability, leading to the plasma jet flame splitting. Understanding the effects of changing the strength of the external magnetic field on the plasma properties provides the ability to control the plasma Permart to make it suitable for many applications. [ABSTRACT FROM AUTHOR]

Seamless integration of microstructures and circuits on three-dimensional (3D) complex surfaces is of significance and is catalyzing the emergence of many innovative 3D curvy electronic devices. However, patterning fine features on arbitrary 3D targets remains challenging. Here, we propose a facile charge-driven electrohydrodynamic 3D microprinting technique that allows micron- and even submicron-scale patterning of functional inks on a couple of 3D-shaped dielectrics via an atmospheric-pressure cold plasma jet. Relying on the transient charging of exposed sites arising from the weakly ionized gas jet, the specified charge is programmably deposited onto the surface as a virtual electrode with spatial and time spans of ~mm in diameter and ~µs in duration to generate a localized electric field accordantly. Therefore, inks with a wide range of viscosities can be directly drawn out from micro-orifices and deposited on both two-dimensional (2D) planar and 3D curved surfaces with a curvature radius down to ~1 mm and even on the inner wall of narrow cavities via localized electrostatic attraction, exhibiting a printing resolution of ~450 nm. In addition, several conformal electronic devices were successfully printed on 3D dielectric objects. Self-aligned 3D microprinting, with stacking layers up to 1400, is also achieved due to the electrified surfaces. This microplasma-induced printing technique exhibits great advantages such as ultrahigh resolution, excellent compatibility of inks and substrates, antigravity droplet dispersion, and omnidirectional printing on 3D freeform surfaces. It could provide a promising solution for intimately fabricating electronic devices on arbitrary 3D surfaces. [ABSTRACT FROM AUTHOR]

Epidermal melanin synthesis determines an individual's skin color. In humans, melanin is formed by melanocytes within the epidermis. The process of melanin synthesis strongly depends on a range of cellular factors, including the fine-tuned interplay with reactive oxygen species (ROS). In this context, a role of cold atmospheric plasma (CAP) on melanin synthesis was proposed due to its tunable ROS generation. Herein, the argon-driven plasma jet kINPen® MED was employed, and its impact on melanin synthesis was evaluated by comparison with known stimulants such as the phosphodiesterase inhibitor IBMX and UV radiation. Different available model systems were employed, and the melanin content of both cultured human melanocytes (in vitro) and full-thickness human skin biopsies (in situ) were analyzed. A histochemical method detected melanin in skin tissue. Cellular melanin was measured by NIR autofluorescence using flow cytometry, and a highly sensitive HPLC-MS method was applied, which enabled the differentiation of eu- and pheomelanin by their degradation products. The melanin content in full-thickness human skin biopsies increased after repeated CAP exposure, while there were only minor effects in cultured melanocytes compared to UV radiation and IBMX treatment. Based on these findings, CAP does not appear to be a useful option for treating skin pigmentation disorders. On the other hand, the risk of hyperpigmentation as an adverse effect of CAP application for wound healing or other dermatological diseases seems to be neglectable. [ABSTRACT FROM AUTHOR]

Polymers are essential in several sectors, yet some applications necessitate surface modification. One practical and eco-friendly option is non-thermal plasma exposure. The present research endeavors to examine the impacts of dielectric barrier discharge atmospheric pressure plasma on the chemical composition and wettability properties of acrylonitrile butadiene styrene surfaces subject to the action of additive manufacturing. The plasma source was produced by igniting either helium or argon and then adjusted to maximize the operational conditions for exposing polymers. The drop in contact angle and the improvement in wettability after plasma exposure can be due to the increased oxygen-containing groups onto the surface, together with a reduction in carbon content. The research findings indicated that plasma treatment significantly improved the wettability of the polymer surface, with an increase of up to 60% for both working gases, while the polar index increased from 0.01 up to 0.99 after plasma treatment. XPS measurements showed an increase of up to 10% in oxygen groups at the surface of He–plasma-treated samples and up to 13% after Ar–plasma treatment. Significant modifications were observed in the structure that led to a reduction of its roughness by 50% and also caused a leveling effect after plasma treatment. A slight decrease in the glass and melting temperature after plasma treatment was pointed out by differential scanning calorimetry and broadband dielectric spectroscopy. Up to a 15% crystallinity index was determined after plasma treatment, and the 3D printing process was measured through X-ray diffraction. The empirical findings encourage the implementation of atmospheric pressure plasma-based techniques for the environmentally sustainable manipulation of polymers for applications necessitating higher levels of adhesion and specific prerequisites. [ABSTRACT FROM AUTHOR]

In this study, pure iron oxide nanostructures were prepared by a physical method (laser-induced plasma) inside a vacuum using a second harmonic laser Nd: YAG with a wavelength of 532 nm, a laser energy of 500 mJ and a number of pulses of 300 pulses per second. The effect of the plasma generated from argon gas under normal atmospheric pressure was studied using a "cold plasma jet" system with an output voltage of 13 kV and a frequency of 50 Hz. Iron oxide nanostructures were exposed to cold plasma for different periods. The optical and structural properties of the nanostructures were measured before and after exposure, and there was a clear change in them, thus improving the properties of the nanostructures for use in industrial applications such as gas sensors, photovoltaic cells, diodes, detectors, and solar cells. [ABSTRACT FROM AUTHOR]

A system for microwave diagnostics of low-temperature non-stationary atmospheric plasma jets is proposed, the principle of operation of which is based on the registration of changing in the quality factor of the main mode of the electric type of a cylindrical microwave cavity resonator. The time dependences of the average volumetric conductivity of a plasma jet of a barrier discharge in a helium flow are measured. The discharge was powered from an alternating voltage source with a frequency of 9 kHz. Such a low frequency of the supply voltage made it possible to distinguish individual pulses of breakdowns of the barrier discharge. [ABSTRACT FROM AUTHOR]

This work discusses the synthesis of (Cu-Se) core-shell nanoparticles using a plasma jet, using aqueous solutions of copper and selenium salts as a precursor. The structural properties of the resultant (Cu-Se) core-shell nanostructures were examined using UV, XRD, and SEM. The diameter of the granules with a concentration of 3:7 is 17 nm. Thus, utilising the designated diameter. Next, a comparison was made between the MDA cell line—which had been treated to Cu-Se NPs as an anti-cancer (breast cancer) agent—and the normal cell line REF. For every set, the following parameter was evaluated: (i) the proportion of breast cancer cells whose proliferation was inhibited after exposure for (24, 48) hours; (ii) the cytotoxicity of normal cells after (24, 48) hours. We diluted the nanomaterial five times and found that the cytotoxicity in normal cells does not exceed 22%, indicating that its effect is not detrimental to normal cells. Meanwhile, the nanomaterial’s effects were observed on cancer cells after 24 hours, at roughly 63%, and after 48 hours, at roughly 93%, and the census was carried out with these cells. [ABSTRACT FROM AUTHOR]

In this Experiment, the impact of "Dielectric Barrier Discharge (DBD) Plasma jet" (5.47 watt) on activation and germination of Squash seeds (Cucurbita pepo L.) is studied at various periods. The seeds are divided into (soaked seeds and dry seeds). After exposing the seeds, measurements are taken for three germination characteristics (root length, shoot length, and number of leaves). The results show that exposing the plasma jet on the seeds soaked with water is better than dry seeds. Results of plasma exposure on soaked plant seeds at root length at exposure time (5 minutes) show superiority to control by 15.80% while there is no effect at (0.5 minutes) on dry seeds is shown during different exposure times (0.5, 1, 3, 5 min), and a clear increase is shown in shoot length and number of leaves compared to the control group. This indicates that the discharge of the plasma dielectric barrier contributes to stimulating the seeds and increasing their germination rate. [ABSTRACT FROM AUTHOR]

As carbon monoxide has a broad spectrum of biological activities, its production by plasma is a significant advantage in medicine. This paper presents a comparative study of the CO production of two plasma jets: a MHz‐jet and a kHz‐jet. Both were fed with a helium gas with CO2 ${\text{CO}}_{2}$ admixture (0%–1%). CO was produced by CO2 ${\text{CO}}_{2}$ dissociation and its maximal concentration was hundreds of parts per million, which is safe for clinical applications. For the same specific energy input, the CO production was more efficient for the kHz‐jet than the MHz‐jet. Both had antibacterial properties on Escherichia coli, and the addition of CO2 ${\text{CO}}_{2}$ improved them for the MHz‐jet, while it reduced them for the kHz‐jet. [ABSTRACT FROM AUTHOR]

We report on a methodology for measuring the energy dissipated per AC high voltage cycle in a cold atmospheric pressure plasma jet (CAPJet). This method is adapted from research by Nisol et al. on plasma polymerization of hexamethyldisiloxane (HMDSO) organosilicon vapor in a large area planar dielectric barrier discharge (DBD) reactor. Here too, we measured ΔEg, the energy difference with and without small HMDSO vapor concentrations in the argon carrier gas flow. From ΔEg we then derived Em, the energy per molecule, and compared values with those of Nisol. Good agreements were found, including in film structures determined from attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectra, thus suggesting that realistic Em values can be successfully obtained also for the CAPJet case. [ABSTRACT FROM AUTHOR]

Aiming to enhance the potential applications of bioproducts, we developed an innovative approach for their hydrophobization using plasma activation of liquids. In this study, microparticles of vegetable ivory, a porous hygroscopic material, were treated by an air plasma jet while immersed in silicone oil. The in‐liquid plasma treatment formed coatings that reduced particle water vapor sorption. Pore surface coverage and sorption reduction were enhanced by mixing silicone oil with copaiba oil‐resin (Copaifera spp.). Mulateiro extract (Calycophyllum spruceanum) was not as effective, owing to a lower affinity with silicone oil. For the first time, we demonstrate the plasma‐induced coating formation on particles immersed in liquid mixtures, a process in which liquid–liquid interfacial properties play a fundamental role. [ABSTRACT FROM AUTHOR]

Cold atmospheric plasma (CAP) has gained significance in recent years and different prospects of it have been studied widely owing to its effectiveness and eco‐friendly nature. CAP has been used extensively in wound healing. However, a detailed understanding of the interaction of the CAP with different protein macromolecules present in our body is essential. In this study, we emphasize how CAP affects the protein fibrinogen. Fibrinogen is a major protein involved in blood clotting and the major protein in the blood. Numerous spectroscopic investigations have been done including UV spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), and Zeta. This work shines a light on protein self‐assembly to bring the future possibilities of bio‐medicine with CAP treatment. Fibrinogen undergoes structural changes around tryptophan residue as evidenced by UV spectroscopy and quenching in fluorescence spectroscopy. The order of the fluorescence quenching is Oxygen > Helium > Argon gas plasma. 2,4‐dinitrophenylhydrazine (DNPH) assay supports fluorescence studies as more protein carbonyls are formed in the case of argon and oxygen gas plasma. DLS and Zeta potential measurements prove that the protein Fibrinogen undergoes a self‐assembly process to form organized assemblies in the presence of a plasma jet. Reactive oxygen and reactive nitrogen species produced in the plasma have been evaluated using various assays and correlated with the other studies. This study will help understand protein fibrinogen's self‐assembly process and pave the way for the CAP application in wound healing. [ABSTRACT FROM AUTHOR]

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An atmospheric pressure jet that effectively prevents inner wall deposition has been developed, and its precursor distribution and thin-film deposition characteristics have been studied. The laser scattering and fluid simulation results show that the precursor (C4H10Zn) flow out of the eight holes of the central electrode and diffuse into the discharge region. Under the action of a discharge gas (Ar) of 2 slm is blown out of the plasma jet device, and will not diffuse to the inner wall of the plasma jet device. The optical photographs of the discharge show that the site of the monomer cleavage is about 1 mm closest to the inner wall of the jet device. With optical emission spectra (OES), a large number of characteristic emission peaks of Zn and CH were detected. The pattern of the deposited film closely resembles the diffusion pattern of the precursor within the plasma jet apparatus. By investigating deposited films in different regions, the influence of precursor distribution on film morphology and composition has been studied. XPS detected films near (black film) and far (white film) from the central region, and the results showed that films near the central region contained more organic components. This plasma device offers a stable plasma plume for thin film deposition and nanoparticle preparation. [ABSTRACT FROM AUTHOR]

Atmospheric plasma jets generated from air or nitrogen using commercial sources with relatively high energy densities are commonly used for industrial applications related to surface treatments, especially to increase the wettability of polymers or to deposit thin films. The heat fluxes to which the substrates are subjected are typically in the order of 100–300 W/cm2, depending on the treatment conditions. The temperature rise in the treated polymer substrates can have critical consequences, such as a change in the surface crystallinity or even the surface degradation of the materials. In this work, we report the phase transitions of two semicrystalline industrial-grade polymer resins reinforced with glass fibers, namely polyphenylene sulfide (PPS) and polyphthalamide (PPA), subjected to plasma treatments, as well as the modeling of the associated heat transfer phenomena using COMSOL Multiphysics. Depending on the treatment time, the surface of PPS becomes more amorphous, while PPA becomes more crystalline. These results show that the thermal history of the materials must be considered when implementing surface engineering by this type of plasma discharge.

TiO2/Fe3O4/Carbon (TFC) nanocomposites have attracted attention and are widely applied in various applications. The nanocomposite surface modification is generally required following the synthesis step. This study compares aminated TFC prepared in one- and two-step methods. In the one-step method, the nanocomposite synthesis and amination were conducted simultaneously using the submerged arc discharge method in an ethanol medium with ammonia addition. As a comparison, the two-step method was studied, consisting of the initial synthesis stage conducted using the submerged arc discharge method in an ethanol medium, followed by the surface modification stage performed using an atmospheric pressure plasma jet (APPJ) with Ar gas as the carrier for ammonia vapor. The nanocomposite surface characterization studied using Fourier transform infrared (FTIR) spectroscopy reveals C–N and N–H vibration peaks in both infrared spectra of the resulting nanocomposites produced in one- and two-step processes. However, the energy-dispersive X-ray (EDX) analysis quantitatively shows a greater presence of N elements in the aminated TFC produced in a one-step process. Moreover, the amine quantitative analysis investigated by the Kaiser test confirmed that a relatively higher number of amine groups was successfully attached to the aminated TFC produced in the one-step process of submerged arc discharge in ethanol with ammonia addition. [ABSTRACT FROM AUTHOR]

In recent years, atmospheric-pressure plasma jets have emerged as valuable tools in many application areas, including material modification, environmental remediation and biomedicine. Understanding the discharge characteristics of these plasma jets under various operating conditions is crucial for optimizing process outcomes. This paper presents a two-dimensional fluid model for numerical simulation to study the variation in electron density within an atmospheric-pressure helium plasma jet under different operating conditions. The investigated parameters include helium gas flow rate, voltage amplitude, needle-to-ring discharge gap, and relative permittivity of the dielectric tube. The results reveal that the peak electric field and electron density initially occur at the wall of the dielectric tube and subsequently shift towards the head of the propagating jet. Gas flow rate has minimal impact on the electron density throughout the plasma jet, whereas increasing the needle-to-ring discharge gap significantly decreases the average electron density within the jet. In addition, an increase in the voltage amplitude and the relative permittivity of the dielectric tube enhances the electric field within the discharge space, thereby increasing the electron density in the plasma jet. These findings underscore the importance of understanding the correlation between electron density and operating conditions to precisely control plasma jets and enhance material treatment effectiveness for specific applications. [ABSTRACT FROM AUTHOR]

The formation of a plasma jet by a glow discharge in an air flow in the electrode system of a so-called gliding arc is considered at an average discharge current of 100 mA and an air flow rate of 0.1 g/s. The displacement of a negative glow region over the cathode surface is analyzed using a sectioned plane cathode. A method for the plasma jet diagnostics by measuring the charged particle current on a special diagnostic electrode placed inside the jet is proposed. Based on the data obtained, the characteristic features of the current transfer inside the jet are obtained. The charged particle concentration inside the jet is estimated for the proposed current transfer model. [ABSTRACT FROM AUTHOR]

The plasma jet is a non-surgical and minimally invasive procedure that acts by heating the superficial region of the skin, providing rejuvenation of the region. OBJECTIVE: We sought to compare the clinical and histological effects of direct plasma jet versus electrocarbonization without plasma in the treatment of wrinkles in the upper palpebral region. METHODS: This is a clinical trial in which 20 volunteers participated and divided into two groups: electrocarbonization (EG) and plasma jet (JPG), which were clinically evaluated before and after treatment through evaluation protocols, photographs, and questionnaires. Three treatment sessions were performed in the upper eyelid region with an interval of 30 days. After the treatment, a surgical procedure of upper blepharoplasty was performed on two volunteers to remove a skin fragment and later histological analysis. RESULTS: The JPG showed better clinical responses in rejuvenation. The EG promoted an increase in the number of fibroblasts, the number of blood vessels and the amount of inflammation. The JPG showed an increase in the number of fibroblasts and blood vessels. It was observed that the JPG generated activation of T lymphocytes (CD3), macrophages (CD68), and plasmocytes (CD138); in addition to reducing the number of positive cells for CD57 (NK cells). The satisfaction analysis shows that 100 percent in the JPG considered themselves satisfied with the treatment. CONCLUSION: We verified that in comparison with electrocarbonization, the use of a direct plasma jet promoted tissue improvement at the histological level, in addition to fewer adverse reactions. [ABSTRACT FROM AUTHOR]

This study was aimed to evaluate the effect of plasma activated medium (PAM) on breast cancer cell lines (MCF7 and AMJ13) and compared it to non malignant one (ASCs). The cytotoxic effect of 10,15,20, and 25 min prepared PAM was measured and the results indicated that all cells were influenced in the exposure times (20 and 25)min, especially after 48 hours of incubation with lesser influence on normal cells. Based on the results 20 min was determined as the effective dose on 50% of cancer cells with minimal influence on normal one. Further, tumor necrosis factor-alpha (TNF-α) was assessed and the results indicated reduction in the level of this cytokine after PAM treatment, MCF7 showed significant 2reduction in both incubation intervals while AMJ13 and ASCs significantly varied only after 48hrs.Finally, caspase-9was analyzed to identify the apoptosis route and the obtained data revealed that both MCF7 and AMJ13raisedsignificantlyafter 24 and 48hrs.In contrast, ASC cells revealed non-significant changes in both intervals [ABSTRACT FROM AUTHOR]

In this paper, a cold plasma system utilizing a high voltage of 13.5 kV of alternative (AC) and direct current (DC) was used under atmospheric pressure with argon (Ar)-gas at a flow rate of 2.5 l/min and a flowing time of 4 min to synthesize aluminum oxide (AlO) nanoparticles (NP). From the results, when DC was used, it was found that the absorption spectrum starts at 303 nm and gradually falls to 870 nm. With AC, the absorption spectrum was at 330 nm and then began to fall to 902 nm. The energy gap when utilizing DC and AC was 3.49 and 3.44 eV respectively. The analysis of the X-ray diffraction (XRD) patterns showed the structure of the NPs was amorphous, matching the pattern 42-1746. At DC, the average size of NPs formed, as deduced from the XRD pattern, was 29.56 nm, and it was very close to what appeared in the field emission scanning electron microscopy (FESEM) images, in which the apparent NP size ranged between 20 and 50 nm. The XRD test gave an average NP size of 38.21 nm in AC, while the FESEM images showed a size range of 20-60 nm. At dc, the AlO NPs were aggregated and interconnected, and each set was connected to another set, as shown in the FESEM images. At AC, the shape of the synthesized AlO NPs was quasi-spherical, with slightly elongated particles connected. [ABSTRACT FROM AUTHOR]

In the current study, a square assembly of four quad-atmospheric pressure plasma jets (q-APPJ) is used to treat large-sized chilli seeds simultaneously. Germination and growth characteristics improve significantly after a 10-sec treatment of q-APPJ employing argon as the working gas. Plasma-treated chilli seed is more etched and porous than those untreated seed surface, as shown in scanning electron microscopy. The chemical changes of the plasma-treated seeds showed that the Ar plasma-treatment oxidise the seed surface to enhance their wettability, stimulate the water uptake, increase the water electrical conductivity and result in improved seed germination. In addition, optical emission spectroscopy is used to detect the different plasma species present and evaluate their plasma parameters (electron temperature and density). These positive results suggested that Ar plasma-treatment, in APPJ setup, improve seed germination, and potentially improve crop yield, and food security issues. [ABSTRACT FROM AUTHOR]

Transparent and flexible electronics are emerging technologies with the potential to enable new applications. However, to ensure high‐performance transparent electronics, post‐processing such as thermal annealing and vacuum plasma treatment is necessary, which are difficult to apply to polymer‐based flexible substrates. This study analyzed the feasibility of applying selective Ar plasma jet treatment at atmospheric pressure to transparent flexible electronics. When atmospheric Ar plasma treatment is applied to transparent flexible aluminum‐doped zinc oxide (AZO), it showed a maximum 83.1% improvement in sheet resistance while maintaining a high transmittance performance, of over 70%. To verify the mechanism behind the surface treatment effect using atmospheric Ar plasma, comprehensive analyses are performed using atomic force microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy, which confirmed that the effect is due to oxygen vacancy formation caused by ion bombardment and thermal diffusion. The application of atmospheric plasma treatment to a patterned transparent flexible AZO device resulted in a reduction in contact resistance, and it is confirmed that the performance improvement effects can be retained for >500 h by applying additional passivation. [ABSTRACT FROM AUTHOR]

A comprehensive analysis of the individual plasma characteristics and the physical processes involved in the organization of nanoscale solid-state systems throughout a wide spectrum of elemental composition, structural configuration, and dimensionality is presented here. As a result of these phenomena, it may be possible to localize and regulate matter and energy at the nanoscale and to create self-organized nanosolids with exceptional and unique properties. The introduction of a unified conceptual framework that is based on the regulation of the creation, transport, and self-organization of precursor species is followed by the explanation of a number of plasma-specific nonequilibrium and kinetics-driven phenomena that occur over a wide range of temporal and geographical scales. When the plasma is brought down to dimensions of micrometers and nanometers, new emergent phenomena come into play. Examples include chirality-controlled single-walled carbon nanotubes, semiconducting quantum dots and nanowires, ultra-fine manipulation of graphenes, nanodiamonds, and organic matter, as well as nanoplasma effects and nanoplasmas of various states of matter. Over the last several years, there has been intense research into the use of plasma medicine. Due to the vast range of cancer cell selectivity, treating every form of cancer is still a challenging endeavor for medical professionals. Plasma jets and dielectric barrier discharges are two examples of the many varieties of nonthermal plasma devices that have been developed as a result of research in more sophisticated forms of plasma physics. When nonthermal plasma is brought into contact with biological material, a great number of charged particles and reactive species are produced. The primary components consist of plasma ultra-violets, reactive nitrogen species, and reactive oxygen species. These species may be employed alone or in combination with nanomaterials in a variety of biomedical applications that aim to improve human health. They may also be used in the synthesis of nanomaterials with physiological significance. Several different biomedical applications are described in relation to the synergy that may be achieved between plasma and nanomaterials in this study, along with new developments in plasma-based synthesis of physiologically relevant nanomaterials. [ABSTRACT FROM AUTHOR]

This study compares the effects of plasma jet and plasma-activated water on teeth root canals contaminated with Escherichia coli bacteria. A plasma jet system was developed for biological purposes that operate at atmospheric pressure. The plasma jet works with argon gas and is generated by a power supply, which supplies a sinusoidal alternating voltage of 12 kV of 20 kHz frequency. The system was optically diagnosed, as it was found that the peaks of the nitrogen spectrum were obtained at the wavelength (300- 450) nm with the appearance of hydroxide peaks at 380 nm. Extracted teeth with one root canal were used, which were contaminated with bacteria and divided into two groups to be treated with a plasma jet and plasma-activated water. The first group was treated with a plasma jet at a gas flow of 2.5 L/min with a change of treatment time from 0.5 to 3 minutes. The number of killed bacteria colonies increased when the exposure time increased (2.7×108 CFU per mL - 0), and the total killing of bacteria was obtained at 3 minutes treatment time. While the second group was treated with plasma-activated water; the water used to kill the bacteria was treated with plasma for one hour at a gas flow rate of 1 L/min. The measured concentrations of (NO2, NO3, and H2O2) of this water were (10, 100 and 200) ppm. The teeth were treated with plasma-activated water for different times that ranged between (5- 35) minutes. Different bacterial killing rates were obtained at these times, and the total bacterial killing rate was obtained for 35 minutes of treatment time. The obtained results found that the response of bacteria to treatment with plasma jet is better than treatment with plasma-activated water. [ABSTRACT FROM AUTHOR]

The present study investigated the production of reactive chlorine species (RCS) by Ar/O2 and He/O2 radiofrequency plasma jets in saline solution, and the sensitivity of the liver cancer cell line HepG2 to RCS and H2O2. Both plasma jets were able to produce RCS; however, at similar plasma powers, pressures, and feed gas flow rates, the He/O2 jet was more efficient for RCS production. The lower RCS yield in the case of the Ar/O2 plasma jet was mainly due to the higher RCS quenching. At a low production rate, RCS can be produced in the open air. Viability tests showed that HepG2 cells were more sensitive to H2O2 than RCS. [ABSTRACT FROM AUTHOR]

Antibacterial properties and chemical changes of two culture media, Dulbecco's Modified Eagle Medium (DMEM) and Roswell Park Memorial Institute (RPMI), treated by RF‐driven He/O2 plasma jet, were studied using various chemical diagnostics and assessing Escherichia coli inactivation. The antibacterial effect increased with the plasma treatment time and was stronger in RPMI than in DMEM. Formation of organic mono‐ and dichloramines of amino acids in DMEM/RPMI by hypochlorite produced by the reaction of plasma‐generated O atoms with Cl− ions present in culture media were the major causes of the biocidal activity. This behavior was attributed to the action of tertiary chemical products formed by the decay of organic dichloramines. The thiobarbituric acid assay revealed malondialdehyde formation from glucose oxidation as the major component of the media. [ABSTRACT FROM AUTHOR]

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In this comparative study, the bacterial inactivation efficiency of plasma-activated water (PAW) generated by two distinct plasma reactors, one utilizing a nitrogen plasma jet electrode and the other a hybrid argon plasma reactor, was explored. The present study involved the assessment of antimicrobial activity against suspensions of three Gram-positive and three Gram-negative bacterial strains in their planktonic cell state. Bacterial suspensions were introduced into PAW five days after generation. Subsequently, the viability of the bacteria was assessed at various time intervals, specifically at 0.5, 1, 3, 5, 10, and 24 h, in order to evaluate the effect of inactivation. Structural changes in bacteria after PAW treatment were assessed using a scanning electron microscope (SEM). The physicochemical properties of PAW, including pH, conductivity, and concentrations of H2O2, NO2−, and NO3− during aging were measured. The present study demonstrated the effective inactivation of the tested bacterial strains by PAW. Gram-positive bacteria displayed greater resistance compared to Gram-negative species, with the lowest reductions in bacterial counts observed for B. cereus, and the highest for Escherichia coli O157:H7. Morphological damage was evident across all bacterial species examined. Physicochemical measurements showed slow decay of the reactive species in the aging process. This study illustrated the potential utility of PAW as an alternative disinfectant. [ABSTRACT FROM AUTHOR]

The penetration and propagation of streamers in capillary tubes is critical for applications involving the plasma-enabled disinfection of medical devices like catheters and plasma catalysis. In this study, a guided streamer is generated in a pulsed plasma jet operating in helium and impinged downstream onto a capillary tube with an inner diameter between 75 and 500 µm. The threshold voltage required to start the penetration of the guided streamer into the capillary was determined for both positive and negative polarities, and we observed a time delay between the streamer striking the top of the capillary and its penetration, which was found to be larger for the positive than the negative streamer. The observed differences can be explained by the need to sustain an electric field large enough to generate a sufficient seed electron density in the capillary to launch the streamer. The reported results suggest that the electric field at the capillary inlet is likely reduced by the formation of strong surface ionization waves for positive streamers. Nonetheless, in the case of positive streamers, the formation of surface streamers along the outside of the capillary wall can enhance streamer penetration into the capillary and the streamer propagation speed.

Methicillin-resistant Staphylococcus aureus (MRSA) often causes serious infections in hospitals. Vancomycin is widely accepted as the standard therapy for MRSA infection, but its widespread use has resulted in the generation of vancomycin-resistant S. aureus (VRSA). To reduce the potential risk of MRSA and VRSA emergence in aquatic environments, we investigated the degradation of methicillin and vancomycin by cold atmospheric pressure plasma jet (APPJ) irradiation using N2, O2, and CO2 gases. The concentrations of methicillin and vancomycin in distilled water were decreased in a time-dependent manner by the plasma jet irradiation; that is, compared with the pre-treatment levels, the concentrations of methicillin and vancomycin were reduced by 20 to 50% after plasma jet irradiation for 10 s. No methicillin and vancomycin signals were detected after 300 s irradiation. Reactive species generated from the plasma jet electrophilically attacked and fragmented the antibiotic molecules. The present method realizes direct plasma ignition in a solution, and therefore, the reactive species can easily react with antibiotic molecules. In addition, plasma can be generated from various gas species that are abundant in the atmosphere. Therefore, cold APPJ irradiation can be a powerful, cost-effective, and environmentally friendly means for the treatment of antibiotics in aqueous samples.